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  • 1.
    Ahlgren, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Fondell, Amelie
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Gedda, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Swedish Radiat Safety Author, Res Unit, Solna Strandvag 96, SE-17116 Stockholm, Sweden.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    EGF-targeting lipodisks for specific delivery of poorly water-soluble anticancer agents to tumour cells2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 36, p. 22178-22186Article in journal (Refereed)
    Abstract [en]

    Concerns regarding poor aqueous solubility, high toxicity and lack of specificity impede the translation of many hydrophobic anticancer agents into safe and effective anticancer drugs. The application of colloidal drug delivery systems, and in particular the use of lipid-based nanocarriers, has been identified as a promising means to overcome these issues. PEG-stabilized lipid nanodisks (lipodisks) have lately emerged as a novel type of biocompatible, nontoxic and adaptable drug nanocarrier. In this study we have explored the potential of lipodisks as a platform for formulation and tumour targeted delivery of hydrophobic anticancer agents. Using curcumin as a model compound, we show that lipodisks can be loaded with substantial amounts of hydrophobic drugs (curcumin/lipid molar ratio 0.15). We demonstrate moreover that by deliberate choice of preparation protocols the lipodisks can be provided with relevant amounts of targeting proteins, such as epidermal growth factor (EGF). Data from in vitro cell studies verify that such EGF-decorated curcumin-loaded lipodisks are capable of EGF-receptor specific targeting of human A-431 tumour cells, and strongly suggest that the interaction between the lipodisks and the tumour cells results in receptor-mediated internalization of the disks and their cargo.

  • 2.
    Ahlinder, Linnea
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Henych, Jiří
    Wiklund Lindström, Susanne
    Ekstrand-Hammarström, Barbro
    Stengl, Václav
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Graphene oxide nanoparticle attachment and its toxicity on living lung epithelial cells2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 73, p. 59447-59457Article in journal (Refereed)
    Abstract [en]

    Since its discovery, graphene and its oxidized form, graphene oxide (GO), have attracted interest in a wide range of technical applications. Concerns about their potential toxicity calls for scrutinized studies, but hitherto conflicting results have been reported which partly may be due to variations of synthesis and exposure procedures. Here we report on the attachment and toxicity of contamination-free graphene oxide nanoparticles (GONP) in living lung epithelial cells. The synthesis of chemically pure GONP was made by an improvement of the Hummer's method based on graphene exfoliated from graphite using high-intensity ultrasonication, resulting in two dimensional sheets with a lateral dimension in the range 200 nm to 3 mu m and thickness of 0.9 nm. Confocal Raman spectroscopy combined with multivariate analysis was used to study the interaction of GONP and living cells. It is shown that overlapping Raman bands due to GONPs and biomolecules in the cells can clearly be separated with this approach. Orthogonal partial least squares discriminant analysis was used to compare spectral data collected from cells exposed to GONP with spectral data collected from non-exposed control cells, and spectral data from cells exposed to a surfactant known to induce apoptosis. Our analyses show that GONP readily attach to the cells, forming sheets which cover a large fraction of the cell surfaces, and induce small chemical changes. In particular, chemical modifications of proteins and lipids in lung epithelial cells are inferred. GONPs do not, however, decrease cell viability. In contrast, enhanced cell proliferation is observed. Our results shed new light on the interactions of GO, and in contrast to some previous reports, suggest that GO is not toxic. The hyperspectral Raman spectroscopy analysis employed here should be applicable for other fields in nanomedicine as a label-free non-perturbing analytical method.

  • 3. Barman, Jharna
    et al.
    Gurav, Deepanjali
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Oommen, Oommen Podiyan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Varghese, Oommen P.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    2 '-N-Guanidino, 4 '-C-ethylene bridged thymidine (GENA-T) modified oligonucleotide exhibits triplex formation with excellent enzymatic stability2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 16, p. 12257-12260Article in journal (Refereed)
    Abstract [en]

    Here we present the synthesis and characterization of a new 2'-N-Guanidino, 4'-C-ethylene bridged thymidine (GENA-T) modified oligonucleotide possessing North-locked sugar conformation. Incorporation of GENA-T nucleotide though did not change the thermal stability of the oligonucleotides toward the complementary RNA; it significantly increased the stability of the parallel triplex at pH 7. The melting temperature of the triplex was increased by +9.5 degrees C as compared to that of the isosequential unmodified sequence. Moreover this modification imparted exceptional nuclease stability to the oligonucleotides for over 33 h. This study clearly demonstrates that GENA-T modified oligonucleotides could improve triplex formation with phenomenal enzymatic stability and could be used for various biomedical applications.

  • 4.
    Behera, Nilamani
    et al.
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Kumar, Ankit
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Chaudhary, Sujeet
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Pandya, Dinesh K.
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Two magnon scattering and anti-damping behavior in a two-dimensional epitaxial TiN/Py(t(Py))/beta-Ta(t(Ta)) system2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 14, p. 8106-8117Article in journal (Refereed)
    Abstract [en]

    The prime requirements for the spin transfer torque based ferromagnetic (FM)/nonmagnetic (NM) bilayer spin devices are (i) the absence of two-magnon scattering (TMS) noise, (ii) minimum energy dissipation and (iii) fast switching. To realize these objectives we have studied the thickness, Py (permalloy) thicknesses (t(Py)) and beta-Ta thicknesses (t(Ta)), dependent magnetization dynamics behaviour of the epitaxial Py (t(Py) = 3-20 nm)/beta-Ta (t(Ta) = 1.5-15 nm) system. The t(Py) dependence of TMS in epitaxial Py nanolayers (t(Py) = 3-20 nm) grown on a Si(400)/TiN(200) (8 nm) substrate is explored in terms of uniform and non-uniform magnetization precession regimes by employing ferromagnetic resonance field (H-r), linewidth (Delta H), and Gilbert damping constant (alpha) behaviour. It is found that in Py, t(Py) < 10 nm, layers TMS is dominating due to non-uniform precession of the magnetization. However in Py, t(Py) >= 10 nm, layers the uniform magnetization precession dominates, therefore Py layers, t(Py) >= 10 nm, are almost free from TMS. Furthermore, a nearly TMS free 12 nm epitaxial Py(200) layer is capped with beta-Ta (t(Ta) = 1.5-15 nm) layers to explore the t(Ta) dependent magnetization precession of epitaxial Py (12 nm) in terms of change in effective Gilbert damping constant (alpha(eff)). An anomalous decrease in alpha(eff) from 0.0087 at t(Ta) = 0 to a minimum value of 0.0077 at t(Ta) = 6 nm, and its subsequent increase for t(Ta) > 6 nm are observed in the epitaxial Py (12 nm)/beta-Ta(t(Ta)) system. Therefore the Si(400)/TiN(200) (8 nm)/Py(200) (12 nm)/beta-Ta(200) (6 nm) epitaxial system with nearly uniform magnetic precession and minimum effective Gilbert damping is suitable for low energy loss and ultrafast switching applications in spin transfer torque devices.

  • 5.
    Bergfelt, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Lacey, Matthew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hedman, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sångeland, Christofer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bowden, Tim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 30, p. 16716-16725Article in journal (Refereed)
    Abstract [en]

    In this work, three types of polymers based on epsilon-caprolactone have been synthesized: poly(epsilon-caprolactone), polystyrene-poly(epsilon-caprolactone), and polystyrene-poly(epsilon-caprolactone-r-trimethylene carbonate) (SCT), where the polystyrene block was introduced to improve the electrochemical and mechanical performance of the material. Solid polymer electrolytes (SPEs) were produced by blending the polymers with 10-40 wt% lithium bis(trifluoromethane) sulfonimide (LiTFSI). Battery devices were thereafter constructed to evaluate the cycling performance. The best performing battery half-cell utilized an SPE consisting of SCT and 17 wt% LiTFSI as both binder and electrolyte; a Li vertical bar SPE vertical bar LiFePO4 cell that cycled at 40 degrees C gave a discharge capacity of about 140 mA h g(-1) at C/5 for 100 cycles, which was superior to the other investigated electrolytes. Dynamic mechanical analysis (DMA) showed that the storage modulus E' was about 5 MPa for this electrolyte.

  • 6.
    Bi, Dongqin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Moon, Soo-Jin
    Häggman, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Yang, Lei
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Nazeeruddin, Mohammad K.
    Graetzel, Michael
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Using a two-step deposition technique to prepare perovskite (CH3NH3PbI3) for thin film solar cells based on ZrO2 and TiO2 mesostructures2013In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, no 41, p. 18762-18766Article in journal (Refereed)
    Abstract [en]

    A two-step deposition technique is used for preparing CH3NH3PbI3 perovskite solar cells. Using ZrO2 and TiO2 as a mesoporous layer, we obtain an efficiency of 10.8% and 9.5%, respectively, under 1000 W m(-2) illumination. The ZrO2 based solar cell shows higher photovoltage and longer electron lifetime than the TiO2 based solar cell.

  • 7.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhang, Peng
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Photocatalysis induces bioactivity of an organic polymer based material2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 101, p. 57715-57723Article in journal (Refereed)
    Abstract [en]

    Several materials, like bioglasses, sintered hydroxyapatite and Ti metals and alloys, have the ability to bond to living bone in vivo, which is a desirable property of biomaterials called bioactivity. In this work, we present a novel strategy to develop bioactivity on the non-bioactive surface of a resin-TiO2 nanocomposite through photocatalysis. The results show that UV irradiation (365 nm, 10 mW cm(-2)) for 8 to 16 h on the resin-TiO2 nanocomposite immersed in water induces bioactivity as indicated by hydroxyapatite growth following immersion of the samples in Dulbecco's phosphate buffered saline for 7 days at 37 degrees C. While a nonirradiated resin-TiO2 surface did not show any hydroxyapatite deposition, a surface after 16 h of UV irradiation was fully covered by hydroxyapatite. In vitro cell adhesion of osteoblast-like MG63 cells confirmed the biocompatibility and bioactivity of the resin-TiO2 surfaces with a hydroxyapatite deposition layer, while the non-irradiated resin-TiO2 surface showed no cell adhesion. Resin-TiO2 nanocomposites, with or without UV irradiation, proved to be nontoxic to two human cell lines, human dermal fibroblasts (hDF) and MG63 cells. It was also shown that an increased dose of UV irradiation decreased bacterial adhesion, which is an additional benefit of the UV treatment and a favourable property for biomedical applications. The combined benefits of biocompatibility, bioactivity, decreased bacterial adhesion and the highly efficient disinfection property of TiO2 photocatalysis under UV light make this resin-TiO2 material an interesting candidate for implant and biomedical device applications.

  • 8.
    Cai, Yixiao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Chen, Song
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Grandfield, Kathryn
    McMaster Univ, Dept Mat Sci & Engn, Hamilton, ON, Canada..
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Fabrication of translucent nanoceramics via a simple filtration method2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 121, p. 99848-99855Article in journal (Refereed)
    Abstract [en]

    Generally, particle packing density, grain size and morphology are the important factors that affect the transparency of ceramics. In order to achieve better transparency of ceramics, efforts should be developed to eliminate or minimize light scattering or absorption. Therefore the porosity and size of crystals in a ceramic body should be strictly controlled. Typical transparent ceramics are fabricated by pressure-assisted sintering techniques such as hot isostatic pressing (HIP), spark plasma sintering (SPS), and pressure-less sintering (PLS). However, a simple energy efficient production method remains a challenge. In this study, we describe a simple fabrication process via a facile filtration system that can fabricate translucent hydroxyapatite based ceramics. The translucent pieces yielded from filtration exhibit optical transmittance that was confirmed by UV spectroscopy. Briefly, the morphology and size of ceramic nanoparticles, filtration pressure and filtration time are important parameters to be discussed. Compared with different hydroxyapatite nanoparticles, spherical nanoparticles easily form a densely packed structure, followed by sintered ceramics. When the strontium content in HA increases, the morphology of HA changes from nano-spheres to nano-rods, following a decrease in transparency. A pressure filtration model combining Darcy's law and the Kozeny-Carman relation has been discussed to simulate and explain why the translucent ceramics can be fabricated via such a simple process. This method could be further applied to prepare other translucent functional ceramics by controlling the size and morphology of ceramic particles.

  • 9.
    Cai, Yixiao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Biomineralization on Single Crystalline Rutile: The Modulated Growth of Hydroxyapatite by Fibronectin in a Simulated Body Fluid2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, p. 35507-35516Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to probe the complex interaction between surface bioactivity and protein adsorption on single crystalline rutile. Our previous studies have shown that single crystalline rutile possessed in vitro bioactivity and the crystalline faces affected the hydroxyapatite (HA) formation. However, upon implantation, a fast adsorption of proteins, from the biological fluids, is intermediated by a water layer towards the biomaterial interface. Thus the effect of protein on the bioactivity must be addressed. In this study, the HA growth dynamics on (001), (100) and (110) faces was investigated in a simulated body fluid with the presence of fibronectin (FN) by two different processes. The surface adhesion of each face before and after FN adsorption, as revealed by direct numerical values, was determined by atomic force microscopy (AFM) based peak force quantitative nanomechanical mapping (PF-QNM) for the first time. The findings suggest the surface energies of FN pre-adsorbed (001), (100) and (110) faces have been enhanced, leading to the subsequent accelerated HA formation. Furthermore, (001) and (100) faces were found to have larger coverage of HA crystals than (110) face at an early stage. In addition, various characterizations were performed to probe the chemical and crystal structures of as-grown biomimetic HA crystals, and in particular, the Ca/P ratio variations at different soaking time points.

  • 10.
    Carboni, Marco
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Naylor, Andrew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Unlocking high capacities of graphite anodes for potassium-ion batteries2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 36, p. 21070-21074Article in journal (Refereed)
    Abstract [en]

    Graphite is considered a promising candidate as the anode for potassium-ion batteries (KIBs). Here, we demonstrate a significant improvement in performance through the ball-milling of graphite. Electrochemical techniques show reversible K-intercalation into graphitic layers, with 65% capacity retention after 100 cycles from initial capacities and extended cycling beyond 200 cycles. Such an affinity of the graphite towards storage of K-ions is explained by means of SEM and Raman analyses. Graphite ball-milling results in a gentle mechanical exfoliation of the graphene layers and simultaneous defect formation, leading to enhanced electrochemical performance.

  • 11.
    Carlsson, Daniel O.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cooxidant-free TEMPO-mediated oxidation of highly crystalline nanocellulose in water2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 94, p. 52289-52298Article in journal (Refereed)
    Abstract [en]

    Selective oxidation of C6 hydroxyls to carboxyls through 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, where the oxidizing species (TEMPO+) is generated by cooxidants, such as NaBrO, NaClO or NaClO2, has become a popular way to modify the surfaces of nanocellulose fibrils in aqueous solutions. Employing highly crystalline nanocellulose from Cladophora sp. algae we demonstrate that the same degree of oxidation (D.O.) can be achieved within approximately the same time by replacing the cooxidants with electrogeneration of TEMPO+ in a bulk electrolysis setup. The D.O. is controlled by the oxidation time and the maximum D.O. achieved (D.O. 9.8%, 0.60 mmol g-1 of carboxylic acids and 0 mmol g-1 aldehydes) corresponds to complete oxidation of the surface-confined C6. This shows that TEMPO+ is not sterically hindered from completely oxidizing the fibril surface of Cladophora nanocellulose, in contrast to earlier hypotheses that were based on results with wood-derived nanocellulose. The oxidation does not significantly affect the morphology, the specific surface area (>115 m2 g-1) or the pore characteristics of the water-insoluble fibrous particles that were obtained after drying, but depolymerization corresponding to [similar]20% was observed. For extensive oxidation times, the product recovery of water-insoluble fibrils decreased significantly while significant amounts of charge passed through the system. This could indicate that the oxidation proceeds beyond the fibril surface, in contrast to the current view that TEMPO-mediated oxidation is confined only to the surface.

  • 12.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Electrochemical TEMPO-mediated Oxidation of Highly Crystalline Nanocellulose in Water2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, p. 52289-52298Article in journal (Refereed)
  • 13.
    Carlsson, Daniel O.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Tailoring porosities and electrochemical properties of composites composed of microfibrillated cellulose and polypyrrole2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 17, p. 8489-8497Article in journal (Refereed)
    Abstract [en]

    Composites of polypyrrole and nanocellulose (PPy/nanocellulose) have a high potential as electrodes in energy-storage devices and as membranes for electrochemically controlled ion-exchange systems. In the present work, it is demonstrated that such composites with 42-72% porosity can be produced by using microfibrillated cellulose (MFC) prepared through enzymatic pretreatment or carboxymethylation, or by using different amounts of MFC in the composite synthesis. Together with previous work, this shows that the porosity of PPy/nanocellulose composites can be tailored from 30 to 98% with increments of similar to 10%. Employing the full porosity range of the composites, it is demonstrated that the electrochemical oxidation rate of the materials depends on their porosity due to limitations in the counter ion diffusion process. By tailoring the porosities of PPy/nanocellulose composites, the electrochemical properties can consequently be controlled. The latter provides new possibilities for the manufacturing of electrochemically controlled ion-extraction and energy storage devices with optimized volumetric energy and power densities.

  • 14. Cheung, Ocean
    Zeolites and related sorbents with narrow pores for CO 2 separation from flue gas2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069Article in journal (Refereed)
  • 15. Cheung, Ocean
    et al.
    Keshavarzi, Neda
    Shakarova, D
    Hedin, N
    Bergstrom, L
    Aluminophosphate monoliths with high CO 2-over-N 2 selectivity and CO 2 capture capacity2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069Article in journal (Refereed)
  • 16.
    Deng, Pan
    et al.
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan, Hubei, Peoples R China.
    Fu, Cheng-Jie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan, Hubei, Peoples R China.
    High purity and viability cell separation of a bacterivorous jakobid flagellate based on a steep velocity gradient induced soft inertial force2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 62, p. 35512-35520Article in journal (Refereed)
    Abstract [en]

    Cell separation is one of the key limiting factors for precise analysis of non-axenic microbial lab cultures or environmental samples, and it remains a challenge to isolate target cells with high purity and viability via high-throughput cell sorting. During the past decade, hydrodynamic microfluidic platforms have attracted great attention in cell preparation for their high efficiency, robust performance and low cost. Here, we employ the use of a low-velocity sheath flow with high viscosity near the wall and a high-velocity sheath flow with low viscosity on the other side of the sample flow in a soft inertial separation chip. This not only prevents hard interactions between cells and chip walls but, in comparison to previous inertial separation methods, generates a significant increase in deflection of large cells while keeping the small ones in the original flow. We first conducted experiments on a mixture of small and large fluorescent particles (1.0 and 9.9 m, respectively) and removed over 99% of the small particles. The separation efficiency was then tested on a culture of a bacterivorous jakobid flagellate, Seculamonas ecuadoriensis fed on the live bacterium, Klebsiella sp. Using our microfluidic chip, over 94% of live bacteria were removed while maintaining high jakobid cell viability. For comparison, we also conducted size-based cell sorting of the same culture using flow cytometry, which is widely used as a rapid and automated separation tool. Compared with the latter, our chip showed more than 40% higher separation efficiency. Thus, our device provides high purity and viability for cell separation of a sensitive cell sample (jakobid cells). Potentially, the method can be further used for applications in diagnostics, biological analyses and environmental assessment of mixed microbial samples.

  • 17.
    Denisova, Aleksandra
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Emanuelsson, Rikard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Expanding the (Cross-)Hyperconjugation of 1,4-Disilacyclohexa-2,5-dienes to Larger Monomers and Oligomers: A Computational Investigation2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 43, p. 36961-36970Article in journal (Refereed)
    Abstract [en]

    We used density functional theory calculations to examine molecules that can be regarded as expanded 1,4-disilacyclohexa-2,5-dienes as well as oligomers based on these or 1,4-disilacyclohexa-2,5-diene with the aim to identify systems with extended (cross-)hyperconjugation. Among the three "expanded 1,4-disilacyclohexa-2,5-dienes" considered cyclobutadisilole is the most interesting as it has a higher thermodynamic stability than the isomeric 1,6-disilacyclodeca-2,3,4,7,8,9-hexaene and significantly lower first electronic excitation energy than 1,6-disilacyclodeca-2,4,7,9-tetraene. Cyclobutadisilole with trimethylsilyl substituents at Si shows particularly low excitations with the first strong transition at 3.46 eV (358 nm), i.e., similar to 1.1 eV lower than in 1,4-disilacyclohexa-2,5-diene. The monomers were connected into oligomers via their Si atoms using bis(dimethylsilanediyl) linkers, and some extended hyperconjugation was revealed. The first allowed UV/Vis excitation in the cyclobutadisilole-based tetramers is calculated at 2.57 eV (482 nm), although the lowering in excitation energies when going from monomer to tetramer is merely similar to 0.5 eV and hyperconjugation has modest impact on geometries. Yet, the tetra(cyclobutadisilole) has a significantly lower first allowed excitation when compared to a previously studied tetra(1,4-disilacyclohexadiene) with first excitation at 3.9 eV (318 nm).

  • 18.
    Dobrota, Ana S.
    et al.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Gutic, Sanjin
    Fac Sci, Dept Chem, Zmaja Bosne 33-35, Sarajevo, Bosnia & Herceg..
    Kalijadis, Ana
    Univ Belgrade, Vinca Inst Nucl Sci, Mike Petrovica Alasa 12-14, Belgrade 11001, Serbia..
    Baljozovic, Milos
    Paul Scherrer Inst, Lab Micro & Nanotechnol, Villigen, Switzerland..
    Mentus, Slavko V.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.;Serbian Acad Arts & Sci, Knez Mihajlova 35, Belgrade 11000, Serbia..
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden..
    Pasti, Igor A.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Stabilization of alkali metal ions interaction with OH-functionalized graphene via clustering of OH groups - implications in charge storage applications2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 63, p. 57910-57919Article in journal (Refereed)
    Abstract [en]

    Graphene synthesized by reduction of graphene oxide, depending on the degree of reduction, retains a certain amount of surface OH groups. Considering the surface OH groups/graphene layer system by means of density functional theory calculations, we evidenced the tendency of OH groups to cluster, resulting in enhanced system stability and no band gap opening. In the oxygen concentration range between 1.8 and 8.47 at%, with the addition of each new OH group, integral binding energy decreases, while differential binding energy shows the boost at even numbers of OH groups. Furthermore, we found that the clustering of OH groups over graphene basal plane plays a crucial role in enhancing the interactions with alkali metals. Namely, if alkali metal atoms interact with individual OH groups only, the interaction leads to an irreversible formation of MOH phase. When alkali atoms interact with clusters containing odd number of OH groups, a reversible transfer of an electron charge from the metal atom to the substrate takes place without OH removal. The strength of the interaction in general increases from Li to K. In an experimental investigation of a graphene sample which dominantly contains OH groups, we have shown that the trend in the specific interaction strength reflects to gravimetric capacitances measured in alkali metal chloride solutions. We propose that the charge stored in OH groups which interact with alkali metal cation and the pi electronic system of the graphene basal plane presents the main part of its pseudocapacitance.

  • 19.
    El-Seedi, Hesham
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi. Jiangsu Univ, Coll Food & Biol Engn, Zhenjiang 212013, Jiangsu, Peoples R China;Al Rayan Coll, Al Rayan Res & Innovat Ctr, Medina 42541, Saudi Arabia;Menoufia Univ, Fac Sci, Dept Chem, Al Minufiyah, Egypt.
    El-Shabasy, Rehan M.
    Menoufia Univ, Fac Sci, Dept Chem, Al Minufiyah, Egypt;KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, Ecol Chem Grp, Stockholm, Sweden.
    Khalifa, Shaden A. M.
    Karolinska Univ Hosp, Clin Res Ctr, Huddinge, Sweden;Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, SE-10691 Stockholm, Sweden.
    Saeed, Aamer
    Quaid I Azam Univ, Dept Chem, Islamabad 45320, Pakistan.
    Shah, Afzal
    Univ Bahrain, Coll Sci, Dept Chem, Sakhir 32038, Bahrain.
    Shah, Raza
    Univ Karachi, Int Ctr Chem & Biol Sci, HEJ Res Inst Chem, Karachi 75270, Pakistan.
    Iftikhar, Faiza Jan
    Quaid I Azam Univ, Dept Chem, Islamabad 45320, Pakistan.
    Abdel-Daim, Mohamed M.
    Suez Canal Univ, Fac Vet Med, Pharmacol Dept, Ismailia 41522, Egypt.
    Omri, Abdelfatteh
    KAU, Ctr Excellence Bionosci Res, Jeddah 21589, Saudi Arabia;KAU, Dept Biol Sci, Biotechnol Res Grp, Fac Sci, Jeddah 21589, Saudi Arabia.
    Hajrahand, Nahid H.
    KAU, Ctr Excellence Bionosci Res, Jeddah 21589, Saudi Arabia;KAU, Dept Biol Sci, Biotechnol Res Grp, Fac Sci, Jeddah 21589, Saudi Arabia.
    Sabir, Jamal S. M.
    KAU, Ctr Excellence Bionosci Res, Jeddah 21589, Saudi Arabia;KAU, Dept Biol Sci, Biotechnol Res Grp, Fac Sci, Jeddah 21589, Saudi Arabia.
    Zou, Xiaobo
    Jiangsu Univ, Coll Food & Biol Engn, Zhenjiang 212013, Jiangsu, Peoples R China.
    Halabi, Mohammed F.
    Al Rayan Coll, Al Rayan Res & Innovat Ctr, Medina 42541, Saudi Arabia.
    Sarhan, Wessam
    Zewail City Sci & Technol, Cairo, Egypt.
    Guo, Weisheng
    Guangzhou Med Univ, Affiliated Hosp 2, Translat Med Ctr, Guangzhou 510260, Guangdong, Peoples R China.
    Metal nanoparticles fabricated by green chemistry using natural extracts: biosynthesis, mechanisms, and applications2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 42, p. 24539-24559Article, review/survey (Refereed)
    Abstract [en]

    Nanoparticles (NPs) are new inspiring clinical targets that have emerged from persistent efforts with unique properties and diverse applications. However, the main methods currently utilized in their production are not environmentally friendly. With the aim of promoting a green approach for the synthesis of NPs, this review describes eco-friendly methods for the preparation of biogenic NPs and the known mechanisms for their biosynthesis. Natural plant extracts contain many different secondary metabolites and biomolecules, including flavonoids, alkaloids, terpenoids, phenolic compounds and enzymes. Secondary metabolites can enable the reduction of metal ions to NPs in eco-friendly one-step synthetic processes. Moreover, the green synthesis of NPs using plant extracts often obviates the need for stabilizing and capping agents and yields biologically active shape- and size-dependent products. Herein, we review the formation of metallic NPs induced by natural extracts and list the plant extracts used in the synthesis of NPs. In addition, the use of bacterial and fungal extracts in the synthesis of NPs is highlighted, and the parameters that influence the rate of particle production, size, and morphology are discussed. Finally, the importance and uniqueness of NP-based products are illustrated, and their commercial applications in various fields are briefly featured.

  • 20.
    Espinosa-Garcia, W. F.
    et al.
    Universidad de San Buenaventura-Medellín, Facultad de Ingenierías, Grupo de Investigación en Modelamiento y Simulación Computacional; Universidad de Antioquia UdeA, Instituto de Física.
    Osorio-Guillen, J. M.
    Universidad de Antioquia UdeA, Instituto de Física.
    Araujo, Carlos Moyses
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Dimension-dependent band alignment and excitonic effects in graphitic carbon nitride: a many-body perturbation and time-dependent density functional theory study2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 71, p. 44997-45002Article in journal (Refereed)
    Abstract [en]

    First-principles many-body theory and time-dependent density functional theory were used to study the dimension effects on the band alignment and optical properties of s-triazine and graphitic C3N4. The inclusion of quasiparticle corrections is very important to describe the quantum confinement and the enhancement of the electron-electron (e-e) interaction. The calculated quasiparticle gaps range from 4.0 eV (monolayer) to 3.21 eV (tetralayer). The position of the valence band maxima is found to be almost constant, whereas the conduction band minima show a strong quantum confinement effect with a variation of similar to 0.7 eV respective to the bulk structure. The calculated frequency-dependent imaginary part of the dielectric function using the Bethe-Salpeter equation shows prominent excitonic effects, where there is a strong redistribution of the spectral weight to lower photon energies in the ultraviolet frequencies where the major part of the absorption occurs. On the other hand, a less intense excitonic absorption in the visible region is due to light polarization perpendicular to the surface plane. In contrast, time-dependent density functional theory also shows a redistribution of the spectral weight in the ultraviolet but it fails to describe the excitonic features in the visible region.

  • 21.
    Farahani, Pooria
    et al.
    Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, BR-05508000 Sao Paulo, SP, Brazil..
    Oliveira, Marcelo A.
    Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, BR-05508000 Sao Paulo, SP, Brazil..
    Fernández Galván, Ignacio
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Baader, Wilhelm J.
    Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, BR-05508000 Sao Paulo, SP, Brazil..
    A combined theoretical and experimental study on the mechanism of spiro-adamantyl-1,2-dioxetanone decomposition2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 28, p. 17462-17472Article in journal (Refereed)
    Abstract [en]

    1, 2-Dioxetanones have been considered as model compounds for bioluminescence processes. The unimolecular decomposition of these prototypes leads mainly to the formation of triplet excited states whereas in the catalysed decomposition of these peroxides singlet states are formed preferentially. Notwithstanding, these cyclic peroxides are important models to understand the general principles of chemiexcitation as they can be synthesised, purified and characterised. We report here results of experimental and theoretical approaches to investigating the decomposition mechanism of spiro-adamantyl- 1,2-dioxetanone. The activation parameters in the unimolecular decomposition of this derivative have been determined by isothermal kinetic measurements (30-70 degrees C) and the chemiluminescence activation energy calculated from the correlation of emission intensities. The activation energy for peroxide decomposition proved to be considerably lower than the chemiluminescence activation energy indicating the existence of different reaction pathways for ground and excited state formation. These experimental results are compared with the calculations at the complete active space second-order perturbation theory (CASPT2), which reveal a two-step biradical mechanism starting by weak peroxide bond breakage followed by carbon-carbon elongation. The theoretical findings also indicate different transition state energies on the excited and ground state surfaces during the C-C bond cleavage in agreement with the experimental activation parameters.

  • 22.
    Fernandes, Daniel L. A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Paun, Cristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Pavliuk, Mariia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Fernandes, Arthur B.
    Univ Sao Paulo, Inst Chem, Dept Fundamental Chem, BR-05508000 Sao Paulo, Brazil..
    Bastos, Erick L.
    Univ Sao Paulo, Inst Chem, Dept Fundamental Chem, BR-05508000 Sao Paulo, Brazil..
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, PL-01224 Warsaw, Poland..
    Green microfluidic synthesis of monodisperse silver nanoparticles via genetic algorithm optimization2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 98, p. 95693-95697Article in journal (Refereed)
    Abstract [en]

    A scalable and green procedure for the microfluidic flow synthesis of monodisperse silver nanoparticles is reported. Beetroot extract is used both as a reducing and growth-regulating agent. A multi-objective genetic algorithm was used to automate the optimization of the reaction and reduce sample polydispersity observed in previous reports. The proposed methodology ensures high-quality nanoparticles in a rapidly manner and devoid of human skill or intuition, essential for method standardization and implementation.

  • 23.
    Frykstrand, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Forsgren, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cheung, Ocean
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhang, Peng
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Hong, Jaan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ferraz, Natalia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Study of mesoporous magnesium carbonate in contact with whole human blood2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 58, p. 52810-52816Article in journal (Refereed)
    Abstract [en]

    The interaction of mesoporours magnesium carbonate (Upsalite) particles (50-100 mm) with human whole blood was investigated using an in vitro loop model and the effect on the complement system, blood coagulation and red blood cell lysis was assessed. The removal of Ca2+ by Upsalite and the possible exchange with and/or release of Mg2+ were explored as well. Upsalite was found to present anticoagulant properties, most probably due to the uptake of Ca2+ by the particles. No hemolytic activity was detected at Upsalite concentrations up to 1 mg ml(-1). Moderate to high levels of C3a and sC5b-9 were observed for Upsalite, however such levels were statistically different from the negative control only when the particle concentrations were 0.25 mg ml(-1) and 1.0 mg ml(-1), respectively. The presented findings are promising for the future development of mesoporous magnesium carbonate-based materials for biomedical applications.

  • 24.
    Gallinetti, Sara
    Technical University of Catalonia (UPC), Barcelona, Spain.
    Nanotopological-tailored calcium phosphate cements for the odontogenic stimulation of human dental pulp stem cells through integrin signaling RSC2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 78, p. 63363-63371Article in journal (Refereed)
  • 25.
    Haldar, Soumyajyoti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Amorim, Rodrigo Garcia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Scheicher, Ralph.H
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rocha, Alexandre R.
    Energetic stability, STM fingerprints and electronic transport properties of defects in graphene and silicene2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 8, p. 6702-6708Article in journal (Refereed)
    Abstract [en]

    Novel two-dimensional materials such as graphene and silicene have been heralded as possibly revolutionary in future nanoelectronics. High mobilities, and in the case of silicene, its seemingly natural integration with current electronics could make them the materials of next-generation devices. Defects in these systems, however, are unavoidable particularly in large-scale fabrication. Here we combine density functional theory and the non-equilibrium Green’s function method to simulate the structural, electronic and transport properties of different defects in graphene and silicene. We show that defects are much more easily formed in silicene, compared to graphene. We also show that, although qualitatively similar, the effects of different defects occur closer to the Dirac point in silicene, and identifying them using scanning tunneling microscopy is more difficult particularly due to buckling. This could be overcome by performing direct source/drain measurements. Finally we show that the presence of defects leads to an increase in local current from which it follows that they not only contribute to scattering, but are also a source of heating.

  • 26.
    Hua, Kai
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Carlsson, Daniel Otto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ålander, Eva
    Lindström, Tom
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ferraz, Natalia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Translational study between structure and biological response of nanocellulose from wood and green algae2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 6, p. 2892-2903Article in journal (Refereed)
    Abstract [en]

    The influence of nanostructure on the cytocompatibility of cellulose films is analyzed providing insight into how physicochemical properties of surface modified microfibrillated cellulose (MFC) and Cladophora nanocellulose (CC) affect the materials cytocompatibility. CC is modified through TEMPO-mediated oxidation and glycidyltrimethylammonium chloride (EPTMAC) condensation to obtain anionic and cationic nanocellulose samples respectively, while anionic and cationic MFC samples are obtained by carboxymethylation and EPTMAC condensation respectively. Films of unmodified, anionic and cationic MFC and CC are prepared by vacuum filtration and characterized in terms of specific surface area, pore size distribution, degree of crystallinity, surface charge and water content. Human dermal fibroblasts are exposed to culture medium extracts of the films in an indirect contact cytotoxicity test. Moreover, cell adhesion and viability are evaluated in a direct contact assay and the effects of the physicochemical properties on cell behavior are discussed. In the indirect cytotoxicity test no toxic leachables are detected, evidencing that the CC and MFC materials are non-cytotoxic, independently ofthe chemical treatment that they have been subjected to. The direct contact tests show that carboxymethylated-MFC presents a more cytocompatible profile than unmodified and trimethylammonium-MFC. TEMPO-CC promotes fibroblast adhesion and presents cell viability comparable to the results obtained with the tissue culture material Thermanox. We hypothesize that the distinct aligned nanofiber structure present in the TEMPO-CC films is responsible for the improved cell adhesion. Thus, by controlling the surface properties of cellulose nanofibers, such as chemistry, charge, and orientation, cell adhesion properties can be promoted.

  • 27.
    Hussain, Afzal
    et al.
    King Saud Univ, Dept Pharmacognosy, Coll Pharm, Riyadh 11451, Saudi Arabia.
    Oves, Mohammad
    King Abdulaziz Univ, Ctr Excellence Environm Studies, Jeddah 21589, Saudi Arabia.
    Alajmi, Mohamed F.
    King Saud Univ, Dept Pharmacognosy, Coll Pharm, Riyadh 11451, Saudi Arabia.
    Hussain, Iqbal
    Jubail Ind Coll, Dept Gen Studies, Jubail Ind City 31961, Jubail, Saudi Arabia.
    Amir, Samira
    Alfaisal Univ, Dept Chem, Coll Sci & Gen Studies, Riyadh 11451, Saudi Arabia.
    Ahmed, Jahangeer
    King Saud Univ, Dept Chem, Coll Sci, Riyadh 11451, Saudi Arabia.
    Rehman, Md Tabish
    King Saud Univ, Dept Pharmacognosy, Coll Pharm, Riyadh 11451, Saudi Arabia.
    El-Seedi, Hesham
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Ali, Imran
    Taibah Univ, Dept Chem, Coll Sci, Al Medina Al Munawara 41477, Saudi Arabia;Jamia Millia Islamia, Dept Chem, New Delhi, India.
    Biogenesis of ZnO nanoparticles using Pandanus odorifer leaf extract: anticancer and antimicrobial activities2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 27, p. 15357-15369Article in journal (Refereed)
    Abstract [en]

    The continuously increasing incidence rates of cancer and infectious diseases are open threats to the sustainable survival of animals and humans. In the last two decades, the demands of nanomaterials as modern therapeutic agents have increased. In this study, biogenic zinc oxide nanoparticles (ZnO NPs) were developed from aqueous Pandanus odorifer leaf extract (POLE) and characterized using modern methods and tools, such as electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy and UV-vis spectroscopy, which indicated the formation of very pure, spherical NPs approximately 90 nm in size. The anticancer activity of the ZnO NPs was evaluated by MTT and neutral red uptake (NRU) assays in MCF-7, HepG2 and A-549 cells at different doses (1, 2, 5, 10, 25, 50, 100 g ml(-1)). Moreover, the morphology of the treated cancer cells was examined by phase contrast microscopy. The results suggest that the synthesized ZnO NPs inhibited the growth of the cells when applied a concentration from 50-100 g ml(-1). Moreover, the biogenic ZnO NPs were analysed as an antimicrobial agent against pathogenic bacteria. The highest antibacterial activity was observed against Gram-positive Bacillus subtilis (26 nm) and Gram-negative Escherichia coli (24 mm) at 50 g per well. Complete bacterial growth (100%) vanished 100% upon treatment with ZnO NPs at 85 g ml(-1). Overall, POLE mediated derived biogenic ZnO NPs could serve as a significant anticancer and antimicrobial agent and be used in the development of novel drugs and skin care products.

  • 28.
    Höglin, Viktor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Cedervall, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Andersson, Mikael Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sarkar, Tapati
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hudl, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. ICT Materials Physics, KTH Royal Institute of Technology.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Phase diagram, structures and magnetism of the FeMnP1-xSix-system2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 11, p. 8278-8284Article in journal (Refereed)
    Abstract [en]

    The magnetic properties of the (Fe,Mn)2(P,Si)-system have been shown to be readily manipulated by small changes in composition. This study surveys the FeMnP1−xSix-system (0.00 ≤ x ≤ 1.00) reporting sample syntheses and investigations of crystallographic and magnetic properties using X-ray powder diffraction and magnetic measurements. Two single phase regions exist: the orthorhombic Co2P-type structure (x < 0.15) and the Fe2P-type structure (0.24 ≤ x < 0.50). Certain compositions have potential for use in magnetocaloric applications.

  • 29.
    Jacobsson, Jesper
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Antireflective coatings of ZnO quantum dots and their photocatalytic activity2012In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 2, no 27, p. 10298-10305Article in journal (Refereed)
    Abstract [en]

    Thin films of ZnO quantum dots of different sizes have been deposited on conducting glass substrates. The films are transparent and work as antireflective coatings in the visible region. The negative absorption reaches down to -0.25 which represent a 77% increase in the transmitted light. Over a large part of the visible spectrum the increased transmittance is over 25%, and we demonstrate this to be a thin film effect. Under simulated solar illumination these films show a relatively high photocatalytic activity towards decomposition of methylene blue. The rate of photodecomposition depends on particle size and the smallest particles, which are less than 4 nm in diameter, show the highest quantum efficiency. We find the overall efficiency to be in the same order of magnitude to what's reported for commercial photocatalytic products like Degussa P25 and Pilkinton Active™, and maybe even somewhat better. We also demonstrate an increased hydrophilicity for the films under UV radiation. The photocatalytic oxidation of water into oxygen as a function of applied bias was measured in a three electrode system. The overall efficiency is small due to the high band gap but the internal quantum efficiency reaches over 10%.

  • 30.
    Jain, Sagar Motilal
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Univ Turin, NIS Nanostruct Interfaces & Surfaces Ctr Excellen, Dept Chem, Via P Giuria 7, I-10125 Turin, Italy.; Swansea Univ, Coll Engn, Bay Campus,Fabian Way, Swansea SA1 8EN, W Glam, Wales.
    Tripathi, Sapana
    Max Planck Inst Intelligent Syst, Dept Magnet Mat, Heisenbergstr 3, D-70569 Stuttgart, Germany.
    Tripathi, Sanjay
    Mahakal Inst Technol & Management, Dept Mech Engn, Dewas Rd, Ujjain 456664, MP, India.
    Spoto, Giuseppe
    Univ Turin, NIS Nanostruct Interfaces & Surfaces Ctr Excellen, Dept Chem, Via P Giuria 7, I-10125 Turin, Italy.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Acid-catalyzed oligomerization via activated proton transfer to aromatic and unsaturated monomers in Nafion membranes: a step forward in the in situ synthesis of conjugated composite membranes2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 106, p. 104782-104792Article in journal (Refereed)
    Abstract [en]

    An approach to perform controlled acid-catalyzed oligomerization via vapor pressure control of thereactions inside Nafion membranes is presented. The interaction of Nafion with several classes ofaromatic (pyrrol, furan, thiophene) and unsaturated (methyl-acetylene) gas phase monomers was studiedas a function of contact time and temperature by in situ vibrational (FTIR) and electronic (UV-Vis)spectroscopy with the support from theoretical linear response and time dependent DFT calculations tomonitor the vibrations and the effective number of conjugated double bonds. The formation ofH-bonded adduct as seen from IR spectroscopy transforms the hydrogen bonded species into positivelycharged oligomers through an activated proton transfer mechanism where oligomerization progressthrough increasing contact time with the respective gas phase reactants at room temperature. Theactivated proton transfer oligomerization proceeds through the stepwise growth propagation cycles viacarbocationic intermediates, finally leads to the formation of irreversible, conjugated charged oligomersas a product. The colored, conjugated oligomeric Nafion composite products are formed at roomtemperature as a function of reaction time and are irreversible after complete degassing of the gas phasereactants as well stable in ambient environment stored for many days in pure oxygen or air and cannotbe extracted with common solvents, appearing strongly encapsulated inside Nafion membranes. This iscrucial for future applications of the presented route for direct production of conjugated species insideNafion and thus production and control of composite membrane materials of interest in fuel cells andcatalysis.

  • 31.
    Josefsson, Gabriella
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Chinga-Carrasco, Gary
    Paper and Fiber Research Institute (PFI AS), Trondheim, Norway.
    Gamstedt, Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Elastic models coupling the cellulose nanofibril to the macroscopic film level2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 71, p. 58091-58099Article in journal (Refereed)
    Abstract [en]

    The mechanical behaviour of cellulose nanofibrils is typically characterized by casting thin films and performing tensile tests on strips cut from these films. When comparing the stiffness of different films, the stiffness of the nanofibrils is only qualitatively and indirectly compared. This study provides some schemes based on various models of fibre networks, or laminated films, which can be used to assess the inherent stiffness of the nanofibrils from the stiffness of the films. Films of cellulose nanofibrils from different raw materials were manufactured and the elastic properties were measured. The expressions relating the nanofibril stiffness and the film stiffness were compared for the presented models. A model based on classical laminate theory showed the best balance between simplicity and adequacy of the underlying assumptions among the presented models. Using this model, the contributing nanofibril stiffness was found to range from 20 to 27 GPa. The nanofibril stiffness was also calculated from mechanical properties of nanofibril films found in the literature and compared with measurements from independent test methods of nanofibril stiffness. All stiffness values were found to be comparable and within the same order of magnitude.

  • 32.
    Kanhere, Pushkar
    et al.
    Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rupp, Caroline J.
    Univ Fed Santa Maria, Dept Fis, BR-97105900 Santa Maria, RS, Brazil..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Chen, Zhong
    Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore..
    Substitution induced band structure shape tuning in hybrid perovskites (CH3NH3Pb1-xSnxI3) for efficient solar cell applications2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 130, p. 107497-107502Article in journal (Refereed)
    Abstract [en]

    Organic-inorganic hybrid perovskite compounds such as CH3NH3PbI3 hold a great potential for low cost photovoltaic devices. Though CH3NH3PbI3 possesses fundamental properties favorable for solar energy harvesting, environmentally safe materials with higher energy efficiency are needed for practical applications. Replacement of lead by tin is a promising solution and investigating the fundamental properties of lead and tin mixed halides is essential. In this article, we have reported electronic and optical properties by employing Density Functional Theory based first principles calculations of Sn doped methyl ammonium lead halide, CH3NH3Pb1-xSnxI3 (x = 0, 0.25, 0.5, 0.75, 1.0). Our results reveal that tin doping narrows the optical band gap allowing absorption of visible light up to 850 nm. Tin doping at Pb sites primarily affects the composition and nature of the valence band maximum. Tin 5p induced electronic states are highly delocalized in nature and are likely to improve the mobility and possible exciton diffusion lengths of holes. Based on the results of this study, 50% Sn doping could to be useful for enhanced performance of perovskite based photovoltaics.

  • 33.
    Kanwal, Nayab
    et al.
    Univ Karachi, Int Ctr Chem & Biol Sci, HEJ Res Inst Chem, Karachi 75270, Pakistan.
    Siddiqui, Amna Jabbar
    Univ Karachi, Int Ctr Chem & Biol Sci, HEJ Res Inst Chem, Karachi 75270, Pakistan.
    Ul Haq, Faraz
    Univ Karachi, Int Ctr Chem & Biol Sci, HEJ Res Inst Chem, Karachi 75270, Pakistan.
    El-Seedi, Hesham R.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi.
    Musharraf, Syed Ghulam
    Univ Karachi, Int Ctr Chem & Biol Sci, HEJ Res Inst Chem, Karachi 75270, Pakistan.
    Two-stage mass spectrometry approach for the analysis of triterpenoid glycosides in Fagonia indica2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 71, p. 41023-41031Article in journal (Refereed)
    Abstract [en]

    Triterpenoid glycosides are molecules widely distributed in plants and have shown a wide range of biological activities against various diseases. This paper describes the qualitative and quantitative analysis of triterpenoid glycoside (saponins) using a two-stage mass spectrometry approach in five samples of Fagonia indica collected from various parts of the country. In the first stage, triterpenoid glycosides were identified using liquid chromatography high-resolution mass spectrometry using UHPLC-QTOF-MS system. In the second stage, compounds were quantified using a multiple reaction monitoring (MRM) approach using an UHPLC-QQQ-MS system. Fagonia indica has shown a wide range of biological activities and found to be rich in saponin or triterpenoid glycoside constituents. A total of thirteen triterpenoid saponins were identified based on high-resolution analysis, MS/MS and database comparison, while six of them were simultaneously quantified using the multiple reaction monitoring (MRM) approach. The results indicate that the samples share a similar UHPLC pattern, however, the amount of these saponins in samples varies greatly. Compound 4i.e. nayabin D was the major constituent (1.4-3.8 g g(-1)) among the six analyzed compounds. The results demonstrated that the developed multi-compound determination in combination with a fingerprint analysis method is rapid, accurate, precise and sensitive and can be utilized for quality control and high-throughput quantification of various saponins in Fagonia indica may be extended to other plant species.

  • 34.
    Karlsson, Christoffer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Huang, Hao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Impact of Linker in Polypyrrole/Quinone Conducting Redox Polymers2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 15, p. 11309-11316Article in journal (Refereed)
    Abstract [en]

    Organic conducting redox polymers are being investigated as the active component for secondary battery applications, as they have the potential to solve two of the main problems with small molecule-based organic electrodes for electrical energy storage, viz dissolution of the active compound in the electrolyte, and slow charge transport through the material. Herein we report the synthesis of a series of conducting redox polymers based on polypyrrole with hydroquinone pendant groups that are attached to the backbone via different linkers, and we investigate the impact of the linker on the interaction between the backbone and the pendant groups. For the directly linked polymer, oxidation of the pendant groups leads to a decrease of bipolaron absorbance, as well as a decrease in mass of the polymer film, both of which are reversible. The origin of these effects is discussed in light of the influence of the linker unit, electrolyte polarity, and electrolyte salt. For the longest linkers in the series, no interaction was observed, which was deemed the most beneficial situation for energy storage applications, as the energy storage capacity of the pendant groups can be utilized without disturbing the conductivity of the polymer backbone.

  • 35.
    Kuang, Guanglin
    et al.
    Royal Inst Technol KTH, AlbaNova Univ Ctr, Sch Biotechnol, Div Theoret Chem & Biol, S-10691 Stockholm, Sweden..
    Zhou, Yang
    Royal Inst Technol KTH, AlbaNova Univ Ctr, Sch Biotechnol, Div Theoret Chem & Biol, S-10691 Stockholm, Sweden..
    Zou, Rongfeng
    Royal Inst Technol KTH, AlbaNova Univ Ctr, Sch Biotechnol, Div Theoret Chem & Biol, S-10691 Stockholm, Sweden..
    Halldin, Christer
    Karolinska Inst, Ctr Psychiat Res, Dept Clin Neurosci, S-17176 Stockholm, Sweden..
    Nordberg, Agneta
    Karolinska Univ Hosp, Ctr Alzheimer Res Translat Alzheimer Neurobiol, Dept Neurobiol Care Sci & Soc, S-14186 Huddinge, Sweden..
    Långström, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Ågren, Hans
    Royal Inst Technol KTH, AlbaNova Univ Ctr, Sch Biotechnol, Div Theoret Chem & Biol, S-10691 Stockholm, Sweden.;Siberian Fed Univ, Inst Nanotechnol Spect & Quantum Chem, Svobodny Pr 79, Krasnoyarsk 660041, Russia..
    Tu, Yaoquan
    Royal Inst Technol KTH, AlbaNova Univ Ctr, Sch Biotechnol, Div Theoret Chem & Biol, S-10691 Stockholm, Sweden..
    Characterization of the binding mode of the PET tracer [F-18] ASEM to a chimera structure of the alpha 7 nicotinic acetylcholine receptor2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 32, p. 19787-19793Article in journal (Refereed)
    Abstract [en]

    The alpha 7 nicotinic acetylcholine receptor (alpha 7-nAChR) is assumed to be implicated in a variety of neurological disorders, such as schizophrenia and Alzheimer's disease (AD). The progress of these disorders can be studied through imaging alpha 7-nAChR with positron emission tomography (PET). [F-18]ASEM is a novel and potent alpha 7-nAChR PET radioligand showing great promise in recent tests. However, the mechanism of the molecular interaction between [F-18] ASEM and alpha 7-nAChR is still unclear. In this paper, the binding profile of [F-18] ASEM to a chimera structure of alpha 7-nAChR was investigated with molecular docking, molecular dynamics, and metadynamics simulation methods. We found that [F-18] ASEM binds at the same site as the crystallized agonist epibatidine but with a different binding mode. The dibenzo[b, d] thiophene ring has a different orientation compared to the pyridine ring of epibatidine and has van der Waals interactions with residues from loop C on one side and p-p stacking interaction with Trp53 on the other side. The conformation of Trp53 was found to have a great impact on the binding of [F-18] ASEM. Six binding modes in terms of the side chain dihedral angles chi(1) and chi(2) of Trp53 were discovered by metadynamics simulation. In the most stable binding mode, Trp53 adopts a different conformation from that in the crystalline structure and has a rather favorable pi-pi stacking interaction with [F-18] ASEM. We believe that these discoveries can be valuable for the development of novel PET radioligands.

  • 36.
    Kumavat, Sandip
    et al.
    HPT Arts & RYK Sci Coll, Dept Phys, Nasik 422005, Maharashtra, India..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rahane, Amol B.
    HPT Arts & RYK Sci Coll, Dept Phys, Nasik 422005, Maharashtra, India..
    Deshpande, Mrinalini D.
    HPT Arts & RYK Sci Coll, Dept Phys, Nasik 422005, Maharashtra, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Royal Inst Technol KTH, Appl Mat Phys, Dept Mat & Engn, S-10044 Stockholm, Sweden..
    Time dependent DFT investigation of the optical response in pristine and Gd doped Al2O32016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 76, p. 72537-72543Article in journal (Refereed)
    Abstract [en]

    The optical absorption spectra and static polarizabilities for the lowest energy configurations of Al2O3 and Gd doped (Al2O3)(n) clusters (n = 1-10) are investigated based on the time-dependent density functional theory (TDDFT) formalism. The polarizabilities of (Al2O3)(n), GdAl2n-1O3n, and Gd2Al2n-2O3n clusters decrease with the increase in size (n) of the cluster. On the other hand, the polarizability of the pristine system increases with the Gd concentration. A systematic study of the optical band gap and HOMO-LUMO gap change for different cluster sizes and Gd concentrations has been envisaged. This could be quite useful from the application perspective of band gap tuning with respect to the cluster size. The study reveals the dependence of both the optical gap and the optical spectra on the geometry, size of the cluster and number of Gd atoms. It is observed that the optical gap oscillates with an increase in the cluster size. With an increase in the number of Gd atoms, a red shift is observed in the optical spectra compared to the pristine system. Interestingly, smooth transitions from discrete to quasi-continuous optical spectra have also been predicted with an increase in size. The simulated spectra exhibit long absorption tails extending deep into the region of lower transition energies.

  • 37.
    Lacey, Matthew J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Yalamanchili, Anurag
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Scania CV AB, SE-15187 Sodertalje, Sweden..
    Maibach, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tengstedt, Carl
    Scania CV AB, SE-15187 Sodertalje, Sweden..
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    The Li-S battery: an investigation of redox shuttle and self-discharge behaviour with LiNO3-containing electrolytes2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 5, p. 3632-3641Article in journal (Refereed)
    Abstract [en]

    The polysulfide redox shuttle and self-discharge behaviour of lithium-sulfur (Li-S) cells containing the electrolyte additive LiNO3 has been thoroughly explored by a range of electrochemical and surface analysis techniques on simple Li-S (i.e., not specifically optimised to resist self-discharge) and symmetrical Li-Li cells. Despite the relatively effective passivation of the negative electrode by LiNO3, fully charged cells self-discharged a quarter of their capacity within 3 days, although in the short-term cells can be recharged without any noticeable capacity loss. The processes governing the rate and reversibility of self-discharge in these cells have been investigated and explained in terms of the reactions of polysulfides occurring at both electrodes during idle conditions.

  • 38.
    Lee, Kian Keat
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Hao, Wenming
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Gustafsson, Mikaela
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Morin, Daniel
    ABB Corp Res, Forskargrand 7, SE-72178 Vasteras, Sweden..
    Bjorkman, Eva
    Biokol Lilliestrale & Co KB, Sibyllegatan 53, SE-11443 Stockholm, Sweden..
    Lilliestrale, Malte
    Biokol Lilliestrale & Co KB, Sibyllegatan 53, SE-11443 Stockholm, Sweden..
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Andersson, Anna M.
    ABB Corp Res, Forskargrand 7, SE-72178 Vasteras, Sweden..
    Hedin, Niklas
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Tailored activated carbons for supercapacitors derived from hydrothermally carbonized sugars by chemical activation2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 112, p. 110629-110641Article in journal (Refereed)
    Abstract [en]

    Activated carbons (ACs) are actively researched as electrode materials for supercapacitors and there is a significant interest to produce ACs from sustainable and low cost precursors. In this study, various ACs were prepared from hydrothermally carbonized sugars by KOH activation. Both the hydrothermal carbonization and activation processes were optimized to tailor the properties (e.g. textural properties, chemical composition, N-doping, electrical conductivity) of the ACs. For instance, the Brunauer-Emmett-Teller (BET) surface areas (S-BET) were tuned in the range of 800-3000 m(2) g(-1) with associated variation in the extent of microporosity and pore size distributions (PSDs). The ACs were evaluated electrochemically as materials for supercapacitor electrodes in a symmetrical two-electrode cell using an aqueous electrolyte. The relationship between the electrochemical, textural, electrical, and physicochemical properties were analyzed systematically to understand the key factors determining the electrochemical performance. A high specific capacitance (C-m) of similar to 260 F g(-1) was achieved at a moderately high S-BET of similar to 1300 m(2) g(-1), which was equivalent to a C-m/S-BET of 20 mu F cm(-2), for an optimal AC prepared from hydrothermally carbonized glucose. The very high surface-specific capacitance highlights that the specific surface area is certainly not the sole limiting parameter for effective electrode materials.

  • 39.
    Lundstedt, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Webb, Matthew J
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Ozonolysis of polycyclic aromatic hydrocarbons in participating solvents2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 10, p. 6152-6159Article in journal (Refereed)
    Abstract [en]

    Seven polycyclic aromatic hydrocarbon (PAH) compounds that can be considered small models for graphene edges have been treated with ozone in solution. The presence of participating solvents such as water or methanol had a pronounced influence on conversion and identity of the functional groups formed, whereas the regioselectivity of the ozonation remained unaffected. Six previously unreported compounds have been isolated from the ozonolysis of pyrene 1, perylene 2 and benzo[e] pyrene 4. Comparison of the experimental data with calculated local ionization energy surfaces (IES) shows a good correlation, and indicates that this computational tool would be useful to predict the regioselectivity of ozone also for larger PAHs, including graphene and graphene nanoribbons.

  • 40.
    Manzetti, Sergio
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology. Fjordforsk Inst Sci & Technol, N-6896 Fresvik, Norway.
    Lu, Tian
    Fjordforsk Inst Sci & Technol, N-6896 Fresvik, Norway.; Univ Sci & Technol Beijing, Sch Chem & Biol Engn, Dept Chem & Chem Engn, Beijing 100083, Peoples R China.
    Alternant conjugated oligomers with tunable and narrow HOMO-LUMO gaps as sustainable nanowires2013In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, no 48, p. 25881-25890Article in journal (Refereed)
    Abstract [en]

    Novel nanowire technologies encompass the use of metals and crystals with a high electric transport potential and superior charge-collection properties. However, nanowires built on metals such as cadmium, gallium-arsenide and similar alloys present serious environmental and health risks. The use of carbon is a far more environmentally friendly solution than heavy-metal based nanowires, and if arranged in a particular manner, it can provide excellent conductive properties that are applicable in nanowire technologies. Herein, we report an investigation into the particular carbon-based 4n/4n + 2 alternant resonance, which has the potential of becoming a key component for the design of novel and conductive nanomaterials, suitable for application in optoelectronics, nanoelectronics and microelectronics. A set of nine 4n/4n + 2 oligomers comprising in the range of 15-20 cyclic units (similar to 5 nm) were analyzed quantum mechanically. The results show that the number and type (4n or 4n + 2) of carbon-rings (cyclobutadiene, benzene and naphthalene) that constitute the oligomers, govern the HOMO-LUMO gaps with a statistical relevance of R-2 = 0.919. Interestingly, we found that the sequence of the units played a central role in shaping the conductance of the 4n/4n + 2 oligomers, and that the sequencing of units in conductive carbon-based oligomers can be a potential future approach in tailoring the gaps of carbon-based conductive components for application in molecular electronics devices. An interesting relationship was also found between the symmetry and the homo-and heteromorphism of the LUMO elements with the HOMO-LUMO gaps, suggesting a pattern of continuity and wavefunction-symmetry across the LUMO orbitals of the 4n/4n + 2 systems to be a key-element determining the narrow gaps in the conductive carbon oligomers. In addition, population and electrostatic potential analysis showed that pi-electron distribution over the oligomers is quite non-uniform. The electron delocalization behavior over the 4n and 4n + 2 rings was characterized by electron localization function, six-center bond order, and a striking linear relationship was found between the pi-delocalization index of the C-C bonds and the HOMO-LUMO gaps (R-2 = 0.988). The results presented herein introduce valuable approaches and data for the engineering of conductive materials to be applied in the field of nanoelectronics and microelectronics, and to relieve the development of nanowires from its dependence on expensive and rare metals.

  • 41.
    Manzetti, Sergio
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics. Fjordforsk AS Inst Sci & Technol, High Performance Computat Unit Midtun, N-6894 Vangsnes, Norway..
    Lu, Tian
    Beijing Kein Res Ctr Nat Sci, Beijing, Peoples R China..
    Behzadi, Hadi
    Kharazmi Univ, Fac Chem, Dept Phys Chem, Tehran, Iran..
    Estrafili, Mehdi D.
    Univ Maragheh, Dept Chem, Lab Theoret Chem, Maragheh, Iran..
    Le, Ha-Linh Thi
    Ecole Polytech, CNRS LPICM, F-91128 Palaiseau, France..
    Vachf, Holger
    Ecole Polytech, CNRS LPICM, F-91128 Palaiseau, France..
    Intriguing properties of unusual silicon nanocrystals2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 95, p. 78192-78208Article in journal (Refereed)
    Abstract [en]

    Solar cell technologies are highly dependent on silicon materials and novel nanoclusters with optimal electronic properties. Based on a recent study on ultrastable silicon nanoclusters, an analysis of the effects of modifications of those nanocrystals by carboxylation, amidation, hydroxylation and halogenation has been performed using quantum mechanical methods of study. Here we report the gaps, electronic structures, absorption spectra, and effects on the charge-transfer potential of a collection of modified silicon nanoclusters. The results show that the pristine silicon clusters retain the highest charge-transfer properties and that halogenation impacts on the charge-transfer effects in a proportional fashion to the electronegativity of the employed halogens. Modification with organic molecules does not improve charge-transfer properties, and gives instead the highest reduction of charge-transfer potentials of the silicon clusters. The effects of the modification have also been studied in context with the orbital configurations through wave function analysis, which reveals that the electrostatic properties of the nanoclusters are mainly represented by a significant polarization of the electrostatic energy between the peripheral regions of the clusters and their core, a feature particularly well-preserved in the pristine silicon clusters. Modifying the particles by adding an extra atom at their core shows significant effects on the molecular orbital properties (HOMO/LUMO). However, this modification does not contribute to an actual increase in charge-transfer integrals. The modifications induce, however, interesting effects on the overall configuration of the clusters; i.e., they increase the aromatic character of the inter-atomic bonding pattern. Halogenation has the highest effect on improving aromatic properties for the silicon clusters, where chlorination gives the highest degree of aromaticity. This study introduces valuable electronic data for engineering novel silicon nanoclusters for application in solar cell technologies, computing units, and other fields such as in aerospace engineering.

  • 42.
    Mihali, Viorica Alina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Renault, Steven
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Benzenediacrylates as organic battery electrode materials: Na versus Li2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 72, p. 38004-38011Article in journal (Refereed)
    Abstract [en]

    This paper discusses investigations of a novel Na-based organic battery electrode material, disodium benzenediacrylate (Na(2)BDA) in comparison with its Li-ion homologue. Li(2)BDA has previously shown promising battery properties, such as stable cycling and good capacity retention. Na(2)BDA and Li(2)BDA are here successfully synthesized and characterized, and investigated as anode materials in prototype Na- and Li-ion battery cells. Moreover, different electrolytes are screened for the Na-battery material, and a useful operating voltage window is explored. Na(2)BDA is shown to possess a higher initial coulombic efficiency (91%) than the Li-homologue, which is uncommon for sodiated organic electrode materials. The Na-compound shows an initial capacity of 177.7 mA h g(-1), which however decreases to ca. 50 mA h g(-1) after 20-100 cycles depending on the cycling rate; a significantly lower capacity retention then that observed for Li(2)BDA. The capacity loss can primarily be explained by a decomposition mechanism of the Na(2)BDA compound.

  • 43. Nandi, Ganesh C.
    et al.
    Kota, Sudhakar R.
    Wakchaure, Prasad B.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Chinthakindi, Praveen K.
    Govender, Thavendran
    Kruger, Hendrick G.
    Naicker, Tricia
    Arvidsson, Per I.
    Pd-catalyzed C-N coupling of vinylbromides and sulfonimidamides: a facile synthesis of N '-vinylsulfonimidamides2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 76, p. 62084-62090Article in journal (Refereed)
    Abstract [en]

    N'-Vinyl sulfonimidamides have been synthesized through a Pd-catalyzed C-N cross coupling between the N'-(imine nitrogen) of N'-deprotected sulfonimidamides and vinyl bromides. The hitherto unreported products were obtained in moderate to excellent yield, and the C-C double bond geometry of the vinylic substrates were retained during the course of reaction. Single crystal X-ray crystallographic analysis confirmed the product structure. Furthermore, we demonstrate that the formed N'-vinyl sulfonimidamides could undergo hydrogenation with Pd-C/H-2 to provide N'-alkyl sulfonimidamides.

  • 44.
    Naqvi, S. Rabab
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hussain, T.
    Univ Queensland, Australian Inst Bioengn & Nanotechnol, Ctr Theoret & Computat Mol Sci, Brisbane, Qld 4072, Australia..
    Panigrahi, P.
    Hindustan Univ, Ctr Clean Energy & Nano Convergence CENCON, Madras, Tamil Nadu, India..
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, SE-10044 Stockholm, Sweden..
    Manipulating energy storage characteristics of ultrathin boron carbide monolayer under varied scandium doping2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 14, p. 8598-8605Article in journal (Refereed)
    Abstract [en]

    We report, for the first time we believe, a detailed investigation on hydrogen storage efficiency of scandium (Sc) decorated boron carbide (BC3) sheets using spin-polarized density functional theory (DFT). We analyzed the energetics of Sc adsorption and explored the most favorable adsorption sites of Sc on BC3 sheets with 3.12%, 6.25%, and 12.5% coverage effects. Our investigations revealed that Sc strongly binds on pristine BC3 sheet, with a minimum binding energy of similar to 5 eV, which is robust enough to hinder Sc-Sc metal clustering. Sc, the lightest transition metal, adsorbs a large number of H-2 molecules per atom, resulting in a reasonable storage capacity. With 12.5% Sc-coverage, functionalized BC3 sheets could attain a H2 storage capacity of 5.5 wt% with binding energies suitable for a practical H-2 storage medium.

  • 45. Ngoc, Trinh Minh
    et al.
    Duy, Nguyen Van
    Hung, Chu Manh
    Hoa, Nguyen Duc
    Trung, Nguyen Ngoc
    Nguyen, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hieu, Nguyen Van
    Ultralow power consumption gas sensor based on a self- heated nanojunction of SnO2 nanowires+2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 63, p. 36323-36330Article in journal (Refereed)
    Abstract [en]

    The long duration of a working device with a limited battery capacity requires gas sensors with low power consumption. A self-heated gas sensor is a highly promising candidate to satisfy this requirement. In this study, two gas sensors with sparse and dense SnO2 nanowire (NW) networks were investigated under the Joule heating effect at the nanojunction. Results showed that the local heating nanojunction was effective for NO2 sensing but generally not for reduction gases. At 1 W, the sparse NW sensor showed a good sensing performance to the NO2 gas. The dense SnO2 NW network required a high-power supply for gas-sensitive activation, but was suitable for reduction gases. A power of approximately 500 W was also needed for a fast recovery time. Notably, the dense NW sensor can response to ethanol and H2S gases. Results also showed that the self-heated sensors were simple in design and reproducible in terms of the fabrication process.

  • 46.
    Papadakis, Raffaello
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Natl Tech Univ Athens, Organ Chem Lab, Sch Chem Engn, Athens 15780, Greece..
    Deligkiozi, Ioanna
    Natl Tech Univ Athens, Organ Chem Lab, Sch Chem Engn, Athens 15780, Greece..
    Giorgi, Michel
    Aix Marseille Univ, CNRS, FR1739, F-13013 Marseille, France..
    Faure, Bruno
    Aix Marseille Univ, CNRS, Cent Marseille, ISM2,UMR 7313, F-13397 Marseille, France..
    Tsolomitis, Athanase
    Natl Tech Univ Athens, Organ Chem Lab, Sch Chem Engn, Athens 15780, Greece..
    Supramolecular complexes involving non-symmetric viologen cations and hexacyanoferrate(II) anions. A spectroscopic, crystallographic and computational study2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 1, p. 575-585Article in journal (Refereed)
    Abstract [en]

    We have investigated spectrally, crystallographically as well as computationally the charge transfer complexes involving newly synthesized N-aryl-N'-methyl non-symmetric viologens (AMVs) and hexacyanoferrate(II) (HCF) anions. The supramolecular binding of AMVs and HCF was studied in solution and in the crystal state for one of the obtained complexes. Substituent effects on the electron affinities of the dicationic AMVs, determined using Mulliken's theory [R. S. Mulliken, J. Am. Chem. Soc., 1952, 74, 811-824] were quantified. The structure of one of the AMV//Fe-II(CN)(6) pairs solved through Single-Crystal X-ray Diffraction (SCXRD), provided insights for the supramolecular binding of the anionic and cationic counterparts and the role of lattice water molecules. Supramolecular binding in solution, studied with the use of NMR spectroscopy, is in agreement with the results obtained in the solid state.

  • 47.
    Paun, Cristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Slowik, Grzegorz
    Marie Curie Sklodowska Univ, Dept Chem Technol, Fac Chem, PL-20031 Lublin, Poland..
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sa, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, PL-01224 Warsaw, Poland..
    Flow hydrogenation of p-nitrophenol with nano-Ag/Al2O32016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 90, p. 87564-87568Article in journal (Refereed)
    Abstract [en]

    Herein, we report the first continuous-flow hydrogenation of p-nitrophenol to p-aminophenol with molecular hydrogen, as a reducing agent. This reaction converts a known pollutant into a high value product with only water as a by product, which is also the solvent. We employed Ag nanoparticles (<5 nm) supported on alumina, which were synthesized directly on low surface area alumina, avoiding the need for catalyst post-processing to confer the required nominal size for flow applications.

  • 48.
    Pazoki, Meysam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Nafari, Nasser
    Taghavinia, Nima
    Ab initio study of electronic effects in the ZnO/TiO2 core/shell interface: application in dye sensitized solar cells2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 1, p. 301-307Article in journal (Refereed)
    Abstract [en]

    Core/shell structure of ZnO nanowires coated with a monolayer of TiO2 is investigated using Density Functional Theory (DFT). The electronic states of the semiconductor is calculated and compared before and after coating of the TiO2 monolayer on a ZnO [10 (1) over bar 0] surface. The effect of TiO2 coating induce surface states changes and shifts the conduction and valence band edges to higher energies. Our results, in qualitative agreement with the experimental work of Matt Law et al. (J. Phys. Chem. B, 110, 22652), show an increase in open circuit voltage and a decrease in short circuit current in ZnO/TiO2 core shell dye sensitized solar cells. Regarding the semiconductor density of states (DOS), TiO2 coated ZnO have more conduction band acceptor states and lower electronic back recombination in agreement with experimental results. Surface dipoles are attributed to changes of the local density of states of the surface. This method can be used for more investigation of starting effects of semiconductor interface and helps the study of surface states and their physical origin in dye sensitized solar cells.

  • 49.
    Pazoki, Meysam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Oscarsson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Yang, L.
    Park, Byung-Wook
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Mesoporous TiO2 microbead electrodes for solid state dye-sensitized solar cells2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 91, p. 50295-50300Article in journal (Refereed)
    Abstract [en]

    Mesoporous TiO2 microbead films have been investigated as working electrodes for solid state dye sensitized solar cells and 3.5% efficiency was achieved for 4 micrometer thick films under 1 sun illumination. Compared to conventional mesoporous solar cells, microbead films have higher porosity, increased open circuit voltage, lower fill factor and current density, faster transport time and lower electron lifetime. Cross sectional scanning electron microscopy results show that the pore filling of a solid hole conductor (spiro-OMeTAD) inside the entire mesoporous bead film is very good even for 4 micrometer thick films. The high porosity of the microbead film allows good penetration of spiro in thick films, while its high surface area ensures good dye coverage. X-ray photoelectron spectroscopy data reveals a lower density of intra-bandgap trap states for microbead films compared to conventional mesoporous TiO2 films, which could be in part responsible for faster transport of electrons and higher voltage in microbead films. Optimization of microbead films for solid state dye sensitized solar cells can be an interesting possibility for highly efficient and relatively thick film solid state solar cells.

  • 50.
    Pazoki, Meysam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Taghavinia, N.
    Abdi, Y.
    Tajabadi, F.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    CVD-grown TiO2 particles as light scattering structures in dye-sensitized solar cells2012In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 2, no 32, p. 12278-12285Article in journal (Refereed)
    Abstract [en]

    Chemical vapour deposition (CVD) at atmospheric pressure, using TiCl 4 as a precursor, was used to grow nanostructured TiO2 films on glass substrates. At relatively low temperatures (∼245 °C) and using relatively high reactant concentrations, different nano-morphologies of TiO2 were formed simultaneously, such as spheres, nanowires and mesoporous structures. The TiO2 spheres were successfully applied as light-scattering particles in dye-sensitized solar cells, either by direct deposition onto electrodes in the reactor, or by preparation of a printing paste from the deposited particles. For dye-sensitized solar cells using the organic dye D35 as sensitizer and a cobalt-complex based redox electrolyte, a solar cell efficiency of 4.4% was obtained using a 5 μm transparent mesoporous TiO 2 layer. Addition of a 5 μm light-scattering CVD-particle film increased the efficiency by 22% to 5.4%, which was similar to the result obtained with an equally thick commercially available light-scattering film (5.3%). Longer electron lifetime was found using CVD-based films, which is attributed to the presence of more traps in the bulk of the material.

12 1 - 50 of 78
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