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Publications (10 of 59) Show all publications
Rubino, S., Akhtar, S. & Leifer, K. (2016). A Simple Transmission Electron Microscopy Method for Fast Thickness Characterization of Suspended Graphene and Graphite Flakes. Microscopy and Microanalysis, 22(1), 250-256
Open this publication in new window or tab >>A Simple Transmission Electron Microscopy Method for Fast Thickness Characterization of Suspended Graphene and Graphite Flakes
2016 (English)In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 22, no 1, p. 250-256Article in journal (Refereed) Published
Abstract [en]

We present a simple, fast method for thickness characterization of suspended graphene/graphite flakes that is based on transmission electron microscopy (TEM). We derive an analytical expression for the intensity of the transmitted electron beam I-0(t), as a function of the specimen thickness t (t < < lambda; where lambda is the absorption constant for graphite). We show that in thin graphite crystals the transmitted intensity is a linear function of t. Furthermore, high-resolution (HR) TEM simulations are performed to obtain lambda for a 001 zone axis orientation, in a two-beam case and in a low symmetry orientation. Subsequently, HR (used to determine t) and bright-field (to measure I-0(0) and I-0(t)) images were acquired to experimentally determine lambda. The experimental value measured in low symmetry orientation matches the calculated value (i.e., lambda = 225 +/- 9 nm). The simulations also show that the linear approximation is valid up to a sample thickness of 3-4 nm regardless of the orientation and up to several ten nanometers for a low symmetry orientation. When compared with standard techniques for thickness determination of graphene/graphite, the method we propose has the advantage of being simple and fast, requiring only the acquisition of bright-field images.

Keywords
graphene, TEM, bright field, thickness maps
National Category
Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-299522 (URN)10.1017/S143192761501569X (DOI)000377142100026 ()26915000 (PubMedID)
Funder
Göran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of Technology
Available from: 2016-07-22 Created: 2016-07-22 Last updated: 2019-04-24Bibliographically approved
Pujari-Palmer, S., Chen, S., Rubino, S., Weng, H., Xia, W., Engqvist, H., . . . Ott, M. K. (2016). In vivo and in vitro evaluation of hydroxyapatite nanoparticle morphology on the acute inflammatory response. Biomaterials, 90, 1-11
Open this publication in new window or tab >>In vivo and in vitro evaluation of hydroxyapatite nanoparticle morphology on the acute inflammatory response
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2016 (English)In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 90, p. 1-11Article in journal (Refereed) Published
Abstract [en]

Biomedical implants have been widely used in bone repair applications. However, nanosized degradation products from these implants could elicit an inflammatory reaction, which may lead to implant failure. It is well known that the size, chemistry, and charge of these nanoparticles can modulate this response, but little is known regarding the role that the particle's morphology plays in inducing inflammation. The present study aims to investigate the effect of hydroxyapatite nanoparticle (HANPs) morphology on inflammation, in-vitro and in-vivo. Four distinct HANP morphologies were fabricated and characterized: long rods, dots, sheets, and fibers. Primary human polymorphonuclear cells (PMNCs), mononuclear cells (MNCs), and human dermal fibroblasts (hDFs) were exposed to HANPs and alterations in cell viability, morphology, apoptotic activity, and reactive oxygen species (ROS) production were evaluated, in vitro. PMNCs and hDFs experienced a 2-fold decrease in viability following exposure to fibers, while MNC viability decreased 5-fold after treatment with the dots. Additionally, the fibers stimulated an elevated ROS response in both PMNCs and MNCs, and the largest apoptotic behavior for all cell types. Furthermore, exposure to fibers and dots resulted in greater capsule thickness when implanted subcutaneously in mice. Collectively, these results suggest that nanoparticle morphology can significantly impact the inflammatory response.

Keywords
Hydroxyapatite nanoparticles; Morphology; Mononuclear cells; Polymorphonuclear cells; Reactive oxygen species; In vivo
National Category
Immunology Biomaterials Science Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-283555 (URN)10.1016/j.biomaterials.2016.02.039 (DOI)000374618100001 ()26974703 (PubMedID)
Funder
VINNOVA, 2010-01907
Available from: 2016-04-13 Created: 2016-04-13 Last updated: 2018-02-08Bibliographically approved
Chen, S., Pujari-Palmer, S., Rubino, S., Westlund, V., Ott, M., Engqvist, H. & Xia, W. (2015). Highly repeatable synthesis of nHA with high aspect ratio. Materials letters (General ed.), 159, 163-167
Open this publication in new window or tab >>Highly repeatable synthesis of nHA with high aspect ratio
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2015 (English)In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 159, p. 163-167Article in journal (Refereed) Published
National Category
Biomaterials Science Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-265712 (URN)10.1016/j.matlet.2015.06.086 (DOI)000362603000043 ()
Funder
Swedish Research Council, 2013-5419VINNOVA, 2010-01907EU, FP7, Seventh Framework Programme, INFRA-2010-262163
Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2018-02-08
Pujari-Palmer, S., Chen, S., Xia, W., Rubino, S., Weng, H., Tang, L. & Ott, M. (2015). Influence of hydroxyapatite nanoparticle morphology on inflammatory response. European Cells and Materials, 29(S1), 43
Open this publication in new window or tab >>Influence of hydroxyapatite nanoparticle morphology on inflammatory response
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2015 (English)In: European Cells and Materials, ISSN 1473-2262, E-ISSN 1473-2262, Vol. 29, no S1, p. 43-Article in journal, Meeting abstract (Refereed) Published
National Category
Medical Materials
Identifiers
urn:nbn:se:uu:diva-284216 (URN)
Available from: 2016-04-15 Created: 2016-04-15 Last updated: 2017-11-30
Pujari-Palmer, S., Chen, S., Xia, W., Rubino, S., Weng, H., Tang, L. & Karlsson Ott, M. (2015). Influence of hydroxyapatite nanoparticle morphology on inflammatory response. European Cells and Materials, 29
Open this publication in new window or tab >>Influence of hydroxyapatite nanoparticle morphology on inflammatory response
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2015 (English)In: European Cells and Materials, ISSN 1473-2262, E-ISSN 1473-2262, Vol. 29Article in journal (Refereed) Published
National Category
Biomaterials Science Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-266009 (URN)
Available from: 2015-11-04 Created: 2015-11-04 Last updated: 2017-12-01
Pujari-Palmer, S., Chen, S., Xia, W., Robino, S., Weng, H., Xia, W., . . . Ott, M. (2015). Influence of hydroxyapatite nanoparticle morphology on inflammatory response. In: : . Paper presented at 8th meeting of the Scandinavian Society for Biomaterials.
Open this publication in new window or tab >>Influence of hydroxyapatite nanoparticle morphology on inflammatory response
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2015 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Medical Materials
Identifiers
urn:nbn:se:uu:diva-284192 (URN)
Conference
8th meeting of the Scandinavian Society for Biomaterials
Available from: 2016-04-15 Created: 2016-04-15 Last updated: 2018-02-08
Thersleff, T., Rusz, J., Rubino, S., Hjörvarsson, B., Ito, Y., Zaluzec, N. J. & Leifer, K. (2015). Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (110) surface using electron magnetic circular dichroism. Scientific Reports, 5, Article ID 13012.
Open this publication in new window or tab >>Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (110) surface using electron magnetic circular dichroism
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2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 13012Article in journal (Refereed) Published
Abstract [en]

Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.

National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-261230 (URN)10.1038/srep13012 (DOI)000359521900001 ()26278134 (PubMedID)
Funder
The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), 1G2009-2017
Note

Correction in: Scientific Reports, 2015, volume: 5, Article Number: 15590, DOI: 10.1038/srep15590

Available from: 2015-09-07 Created: 2015-08-31 Last updated: 2019-04-24Bibliographically approved
Rubino, S., Melin, P., Spellward, P. & Leifer, K. (2014). Cryo-electron Microscopy Specimen Preparation By Means Of a Focused Ion Beam. Journal of Visualized Experiments (89), Article ID e51463.
Open this publication in new window or tab >>Cryo-electron Microscopy Specimen Preparation By Means Of a Focused Ion Beam
2014 (English)In: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, no 89, article id e51463Article in journal (Refereed) Published
Abstract [en]

Here we present a protocol used to prepare cryo-TEM samples of Aspergillus niger spores, but which can easily be adapted for any number of microorganisms or solutions. We make use of a custom built cryo-transfer station and a modified cryo-SEM preparation chamber2. The spores are taken from a culture, plunge-frozen in a liquid nitrogen slush and observed in the cryo-SEM to select a region of interest. A thin lamella is then extracted using the FIB, attached to a TEM grid and subsequently thinned to electron transparency. The grid is transferred to a cryo-TEM holder and into a TEM for high resolution studies. Thanks to the introduction of a cooled nanomanipulator tip and a cryo-transfer station, this protocol is a straightforward adaptation to cryogenic temperature of the routinely used FIB preparation of TEM samples. As such it has the advantages of requiring a small amount of modifications to existing instruments, setups and procedures; it is easy to implement; it has a broad range of applications, in principle the same as for cryo-TEM sample preparation. One limitation is that it requires skillful handling of the specimens at critical steps to avoid or minimize contaminations.

Keywords
Bioengineering, Issue 89, Cryoelectron Microscopy, Life Sciences (General), Cryo-microscopy, Focused ion beam, Sample preparation, TEM, FIB
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:uu:diva-247562 (URN)10.3791/51463 (DOI)000349296100029 ()25146386 (PubMedID)
Available from: 2015-03-20 Created: 2015-03-20 Last updated: 2019-04-24Bibliographically approved
Leifer, K. & Rubino, S. (2014). Development and use of a cryo-FIB-cryo-TEM technique for site-specific lift-out of TEM samples. In: Scandem proceedings: . Paper presented at Scandem conference.
Open this publication in new window or tab >>Development and use of a cryo-FIB-cryo-TEM technique for site-specific lift-out of TEM samples
2014 (English)In: Scandem proceedings, 2014Conference paper, Oral presentation with published abstract (Other academic)
National Category
Natural Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-285255 (URN)
Conference
Scandem conference
Available from: 2016-04-19 Created: 2016-04-19 Last updated: 2019-04-24Bibliographically approved
Thersleff, T., Rusz, J., Rubino, S., Hjörvarsson, B., Ito, Y., Zaluzec, N. & Leifer, K. (2014). Distinguishing overlapping EMCD signals on oxidized metals in the TEM. In: : . Paper presented at 18th International Microscopy Congress.
Open this publication in new window or tab >>Distinguishing overlapping EMCD signals on oxidized metals in the TEM
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2014 (English)Conference paper, Poster (with or without abstract) (Refereed)
Keywords
EMCD, TEM, EELS, Iron, Magnetism
National Category
Metallurgy and Metallic Materials
Research subject
Engineering Science with specialization in Materials Analysis
Identifiers
urn:nbn:se:uu:diva-286748 (URN)
Conference
18th International Microscopy Congress
Available from: 2016-04-21 Created: 2016-04-21 Last updated: 2019-04-24
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5738-0591

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