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Publications (10 of 95) Show all publications
Jones, S. H., King, M. D., Rennie, A. R., Ward, A. D., Campbell, R. A. & Hughes, A. V. (2023). Aqueous Radical Initiated Oxidation of an Organic Monolayer at the Air-Water Interface as a Proxy for Thin Films on Atmospheric Aerosol Studied with Neutron Reflectometry. Journal of Physical Chemistry A, 127(42), 8922-8934
Open this publication in new window or tab >>Aqueous Radical Initiated Oxidation of an Organic Monolayer at the Air-Water Interface as a Proxy for Thin Films on Atmospheric Aerosol Studied with Neutron Reflectometry
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2023 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 127, no 42, p. 8922-8934Article in journal (Refereed) Published
Abstract [en]

Neutron reflectometry has been used to study the radical initiated oxidation of a monolayer of the lipid 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) at the air–solution interface by aqueous-phase hydroxyl, sulfate, and nitrate radicals. The oxidation of organic films at the surface of atmospheric aqueous aerosols can influence the optical properties of the aerosol and consequently can impact Earth’s radiative balance and contribute to modern climate change. The amount of material at the air–solution interface was found to decrease on exposure to aqueous-phase radicals which was consistent with a multistep degradation mechanism, i.e., the products of reaction of the DSPC film with aqueous radicals were also surface active. The multistep degradation mechanism suggests that lipid molecules in the thin film degrade to form progressively shorter chain surface active products and several reactive steps are required to remove the film from the air–solution interface. Bimolecular rate constants for oxidation via the aqueous phase OH radical cluster around 1010 dm3 mol–1 s–1. Calculations to determine the film lifetime indicate that it will take ∼4–5 days for the film to degrade to 50% of its initial amount in the atmosphere, and therefore attack by aqueous radicals on organic films could be atmospherically important relative to typical atmospheric aerosol lifetimes.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
National Category
Physical Chemistry Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:uu:diva-516356 (URN)10.1021/acs.jpca.3c03846 (DOI)001092848100001 ()37830513 (PubMedID)
Available from: 2023-11-21 Created: 2023-11-21 Last updated: 2024-01-25Bibliographically approved
Hemming, J. M., Szyroka, J., Shokano, G., Arnold, T., Skoda, M. W. A., Rennie, A. R. & Thompson, K. C. (2022). Changes to lung surfactant monolayers upon exposure to gas phase ozone observed using X-ray and neutron reflectivity. Environmental Science: Atmospheres, 2(4), 753-760
Open this publication in new window or tab >>Changes to lung surfactant monolayers upon exposure to gas phase ozone observed using X-ray and neutron reflectivity
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2022 (English)In: Environmental Science: Atmospheres, E-ISSN 2634-3606, Vol. 2, no 4, p. 753-760Article in journal (Refereed) Published
Abstract [en]

Exposure to the secondary pollutant ozone in ambient air is associated with adverse health effects when inhaled. In this work we use surface pressure measurements, combined with X-ray and neutron reflection, to observe changes in a layer of lung surfactant at the air water interface when exposed to gas phase ozone. The results demonstrate that the layer reacts with ozone changing its physical characteristics. A slight loss of material, a significant thinning of the layer and increased hydration of the surfactant material is observed. The results support the hypothesis that unsaturated lipids present in lung surfactant are still susceptible to rapid reaction with ozone and the reaction changes the properties of the interfacial layer.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2022
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-485023 (URN)10.1039/d2ea00032f (DOI)000812752900001 ()35923664 (PubMedID)
Available from: 2022-09-21 Created: 2022-09-21 Last updated: 2022-12-08Bibliographically approved
Chien, Y.-C., Lacey, M., Steinke, N.-J., Brandell, D. & Rennie, A. R. (2022). Correlations between precipitation reactions and electrochemical performance of lithium-sulfur batteries probed by operando scattering techniques. Chem, 8(5)
Open this publication in new window or tab >>Correlations between precipitation reactions and electrochemical performance of lithium-sulfur batteries probed by operando scattering techniques
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2022 (English)In: Chem, Vol. 8, no 5Article in journal (Refereed) Published
Abstract [en]

A comprehensive description of electrochemical processes in the positive electrode of lithium-sulfur batteries is crucial for the utilization of active material. However, the discharge mechanisms are complicated due to various reactions in multiple phases and the tortuosity of the highly porous carbon matrix. In this work, simultaneous measurements of small-angle and wide-angle scattering and cell resistance are performed on operating lithium-sulfur cells. Results indicate that precipitates grow mostly in number, not in size, and that the structure of the carbon matrix is not affected. The comparison of the small-angle and wide-angle scattering reveals the amorphous discharge products found at a low discharge rate. Further analysis demonstrates the correlation between the diffusion resistance and the compositional change of electrolyte in the mesopores at the end of discharge, which suggests that Li-ion deficiency is the limiting factor for sulfur utilization at a medium discharge rate.

Place, publisher, year, edition, pages
Elsevier, 2022
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-453434 (URN)10.1016/j.chempr.2022.03.001 (DOI)000805846100008 ()
Available from: 2021-09-16 Created: 2021-09-16 Last updated: 2022-06-27Bibliographically approved
Shepherd, R. H., King, M. D., Rennie, A. R., Ward, A. D., Frey, M. M., Brough, N., . . . Welbourn, R. J. L. (2022). Measurement of gas-phase OH radical oxidation and film thickness of organic films at the air-water interface using material extracted from urban, remote and wood smoke aerosol. Environmental Science: Atmospheres, 2(4), 574-590
Open this publication in new window or tab >>Measurement of gas-phase OH radical oxidation and film thickness of organic films at the air-water interface using material extracted from urban, remote and wood smoke aerosol
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2022 (English)In: Environmental Science: Atmospheres, E-ISSN 2634-3606, Vol. 2, no 4, p. 574-590Article in journal (Refereed) Published
Abstract [en]

The presence of an organic film on a cloud droplet or aqueous aerosol particle has the potential to alter the chemical, optical and physical properties of the droplet or particle. In the study presented, water insoluble organic materials extracted from urban, remote (Antarctica) and wood burning atmospheric aerosol were found to have stable, compressible, films at the air-water interface that were typically similar to 6-18 angstrom thick. These films are reactive towards gas-phase OH radicals and decay exponentially, with bimolecular rate constants for reaction with gas-phase OH radicals of typically 0.08-1.5 x 10(-10) cm(3) molecule(-1) s(-1). These bimolecular rate constants equate to initial OH radical uptake coefficients estimated to be similar to 0.6-1 except woodsmoke (similar to 0.05). The film thickness and the neutron scattering length density of the extracted atmosphere aerosol material (from urban, remote and wood burning) were measured by neutron reflection as they were exposed to OH radicals. For the first time neutron reflection has been demonstrated as an excellent technique for studying the thin films formed at air-water interfaces from materials extracted from atmospheric aerosol samples. Additionally, the kinetics of gas-phase OH radicals with a proxy compound, the lipid 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) was studied displaying significantly different behaviour, thus demonstrating it is not a good proxy for atmospheric materials that may form films at the air-water interface. The atmospheric lifetimes, with respect to OH radical oxidation, of the insoluble organic materials extracted from atmospheric aerosol at the air-water interface were a few hours. Relative to a possible physical atmospheric lifetime of 4 days, the oxidation of these films is important and needs inclusion in atmospheric models. The optical properties of these films were previously reported [Shepherd et al., Atmos. Chem. Phys., 2018, 18, 5235-5252] and there is a significant change in top of the atmosphere albedo for these thin films on core-shell atmospheric aerosol using the film thickness data and confirmation of stable film formation at the air-water interface presented here.

Place, publisher, year, edition, pages
Royal Society of Chemistry (RSC), 2022
National Category
Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:uu:diva-481772 (URN)10.1039/d2ea00013j (DOI)000826362600001 ()
Available from: 2022-08-16 Created: 2022-08-16 Last updated: 2022-12-08Bibliographically approved
Ericsson, A., Pacheco, V., Marattukalam, J. J., Dalgliesh, R. M., Rennie, A. R., Fisk, M. & Sahlberg, M. (2021). Crystallization of a Zr-based metallic glass produced by laser powder bed fusion and suction casting. Journal of Non-Crystalline Solids, 571, Article ID 120891.
Open this publication in new window or tab >>Crystallization of a Zr-based metallic glass produced by laser powder bed fusion and suction casting
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2021 (English)In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 571, article id 120891Article in journal (Refereed) Published
Abstract [en]

The crystallization behavior during low-temperature annealing of samples of the Zr59.3Cu28.8Al10.4Nb1.5 (at%) bulk metallic glass produced by suction casting and the laser powder bed fusion (LPBF) process was studied with small-angle neutron scattering (SANS), X-ray diffraction, and scanning electron microscopy. The in-situ SANS measurements during isothermal annealing reveal that the phase separation in the LPBF processed material proceeds at a smaller characteristic length-scale than the cast material. Quantitative analysis of the SANS data shows that, while the crystallization process in both materials proceeds through rapid nucleation followed by diffusion-limited growth, the LPBF processed material crystallizes with a smaller cluster size and at a higher rate. The smaller cluster size is attributed to the elevated oxygen content in the LPBF processed material which reduces the nucleation barrier and thus the thermal stability.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
AMZ4, Additive manufacturing, Small angle scattering, Crystallization, Oxygen
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:uu:diva-452041 (URN)10.1016/j.jnoncrysol.2021.120891 (DOI)000685499600007 ()
Funder
Swedish Foundation for Strategic Research , GMT14-0048Vinnova, 2020-04526Swedish Foundation for Strategic Research , GSn150008
Available from: 2021-09-02 Created: 2021-09-02 Last updated: 2024-01-15Bibliographically approved
Gelli, R., Tonelli, M., Ridi, F., Bonini, M., Kwaambwa, H. M., Rennie, A. R. & Baglioni, P. (2021). Modifying the crystallization of amorphous magnesium-calcium phosphate nanoparticles with proteins from Moringa oleifera seeds. Journal of Colloid and Interface Science, 589, 367-377
Open this publication in new window or tab >>Modifying the crystallization of amorphous magnesium-calcium phosphate nanoparticles with proteins from Moringa oleifera seeds
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2021 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 589, p. 367-377Article in journal (Refereed) Published
Abstract [en]

Hypothesis: Endogenous Amorphous Magnesium-Calcium Phosphates (AMCPs) form in the human body and, besides their biomedical implications, the development of effective stabilization strategies is an open challenge. An interesting approach consists of stabilizing amorphous phosphates with macromolecules that have beneficial effects from a nutritional/medical point of view, for a potential application of the hybrid particles in nutraceutics or drug delivery.

Experimental: We investigated the effect of proteins extracted from Moringa oleifera seeds (MO) on the features of synthetic analogs of AMCPs and on their crystallization pathway. The stability of the amorphous phase was studied using infrared spectroscopy and X-ray diffraction. To unravel the effect of the protein on the nano-scale structure of the inorganic particles, we also studied how MO affects the features of the amorphous phase using thermal analysis, small angle X-ray scattering and confocal Raman microscopy.

Findings: We observed that MO markedly delays the transition from amorphous to crystalline phosphate in a concentration-dependent fashion. Interestingly, MO not only enhances the lifetime of the amorphous phase, but also influences the type and amount of crystalline material formed. The results are relevant from both a fundamental and an applied perspective, paving the way for the use of these hybrids in the field of nutraceutics and drug delivery.

Place, publisher, year, edition, pages
ElsevierACADEMIC PRESS INC ELSEVIER SCIENCE, 2021
Keywords
Amorphous Mg-Ca phosphates, Moringa oleifera, Amorphous stabilization, Crystallization, AMCP, MO hybrid nanoparticle, microparticle br
National Category
Physical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-439911 (URN)10.1016/j.jcis.2021.01.008 (DOI)000620811700010 ()33476891 (PubMedID)
Funder
Swedish Research Council, 348-2011-7241EU, Horizon 2020, 654000
Available from: 2021-04-19 Created: 2021-04-19 Last updated: 2024-01-15Bibliographically approved
Nouhi, S., Koutsioubas, A., Kapaklis, V. & Rennie, A. R. (2020). Distortion of surfactant lamellar phases induced by surface roughness star. The European Physical Journal Special Topics, 229(17-18), 2807-2823
Open this publication in new window or tab >>Distortion of surfactant lamellar phases induced by surface roughness star
2020 (English)In: The European Physical Journal Special Topics, ISSN 1951-6355, E-ISSN 1951-6401, Vol. 229, no 17-18, p. 2807-2823Article in journal (Refereed) Published
Abstract [en]

Self-assembly is a characteristic property of soft matter. Understanding the factors which assist or perturb this process is of great importance in many biological and industrial processes. Amphiphiles self-assemble and order into a variety of structures including well-ordered lamellar phases. The present work uses neutron reflectometry and neutron scattering to explore the effects of both interface roughness and temperature on the lamellar-phase structure of a non-ionic surfactant at a solid/liquid interface. The structure of concentrated solutions of tetraethyleneglycol dodecyl ether has been compared against a smooth surface and one with a roughness of the order of the lamellar spacing. This has been done in order to investigate the role perturbations have on the overall lamellar order, when these have length scales of the order of the interactions between neighboring lamellae. The results showed that the surfactant forms a well-ordered and aligned structure at a smooth surface, extending to a depth of several micrometers from the interface. Increasing the temperature of the sample and subsequent cooling promotes alignment and increases the number of oriented layers at the surface. The same sample forms a significantly less aligned structure against a rough surface that does not align to the same extent, even after heating. The perturbation of the structure caused by thermal fluctuations was found to be much less than that imposed by a small surface roughness.

Place, publisher, year, edition, pages
SPRINGER HEIDELBERG, 2020
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-428312 (URN)10.1140/epjst/e2020-900220-3 (DOI)000590141900006 ()
Available from: 2020-12-14 Created: 2020-12-14 Last updated: 2020-12-14Bibliographically approved
Gustafsson, E., Bowden, T. & Rennie, A. R. (2020). Interactions of amphiphiles with plasticisers used in polymers: Understanding the basis of health and environmental challenges. Advances in Colloid and Interface Science, 277, Article ID 102109.
Open this publication in new window or tab >>Interactions of amphiphiles with plasticisers used in polymers: Understanding the basis of health and environmental challenges
2020 (English)In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 277, article id 102109Article in journal (Refereed) Published
Abstract [en]

Plasticisers are widely used to provide desirable mechanical properties of many polymeric materials. These small molecule additives are also known to leach from the finished products, and this not only may modify the physical properties but the distribution of these materials in the environment and in the human body can cause long-term health concerns and environmental challenges. Many of these plasticisers are esters of polyvalent acids and phthalic acid has previously been predominant but various alternatives are now being more widely explored. The eventual distribution of these compounds depends not just on solubility in aqueous media and on vapour pressure but also on their interaction with other materials, particularly lipids and amphiphiles. This review provides an overview of both the basic physical data (solubility, partition coefficients, surface tension, vapour pressure) that is available in the literature and summarises what has been learnt about the molecular interactions of various plasticisers with surfactants and lipids.

Place, publisher, year, edition, pages
ELSEVIER, 2020
Keywords
Polyvinyl chloride, Plasticiser, Surfactant, Phthalate esters, Solubility
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-408920 (URN)10.1016/j.cis.2020.102109 (DOI)000521512600004 ()32028074 (PubMedID)
Funder
Swedish Foundation for Strategic Research , GSn15-0008
Available from: 2020-04-17 Created: 2020-04-17 Last updated: 2020-04-17Bibliographically approved
Dicko, C., Engberg, A., Houston, J. E., Jackson, A. J., Pettersson, A., Dalgliesh, R. M., . . . Rennie, A. R. (2020). NUrF-Optimization of in situ UV-vis and fluorescence and autonomous characterization techniques with small-angle neutron scattering instrumentation. Review of Scientific Instruments, 91(7), Article ID 075111.
Open this publication in new window or tab >>NUrF-Optimization of in situ UV-vis and fluorescence and autonomous characterization techniques with small-angle neutron scattering instrumentation
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2020 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 91, no 7, article id 075111Article in journal (Refereed) Published
Abstract [en]

We have designed, built, and validated a (quasi)-simultaneous measurement platform called NUrF, which consists of neutron small-angle scattering, UV-visible, fluorescence, and densitometry techniques. In this contribution, we illustrate the concept and benefits of the NUrF setup combined with high-performance liquid chromatography pumps to automate the preparation and measurement of a mixture series of Brij35 nonionic surfactants with perfluorononanoic acid in the presence of a reporter fluorophore (pyrene).

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2020
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-419706 (URN)10.1063/5.0011325 (DOI)000551855100001 ()32752852 (PubMedID)
Funder
Swedish Research Council, VR-2016-06951
Available from: 2020-09-22 Created: 2020-09-22 Last updated: 2020-09-22Bibliographically approved
King, M. D., Jones, S. H., Lucas, C. O. M., Thompson, K. C., Rennie, A. R., Ward, A. D., . . . Campbell, R. A. (2020). The reaction of oleic acid monolayers with gas-phase ozone at the air water interface: the effect of sub-phase viscosity, and inert secondary components. Physical Chemistry, Chemical Physics - PCCP, 22(48), 28032-28044
Open this publication in new window or tab >>The reaction of oleic acid monolayers with gas-phase ozone at the air water interface: the effect of sub-phase viscosity, and inert secondary components
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2020 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 22, no 48, p. 28032-28044Article in journal (Refereed) Published
Abstract [en]

Organic films that form on atmospheric particulate matter change the optical and cloud condensation nucleation properties of the particulate matter and consequently have implications for modern climate and climate models. The organic films are subject to attack from gas-phase oxidants present in ambient air. Here we revisit in greater detail the oxidation of a monolayer of oleic acid by gas-phase ozone at the air-water interface as this provides a model system for the oxidation reactions that occur at the air-water interface of aqueous atmospheric aerosol. Experiments were performed on monolayers of oleic acid at the air-liquid interface at atmospherically relevant ozone concentrations to investigate if the viscosity of the sub-phase influences the rate of the reaction and to determine the effect of the presence of a second component within the monolayer, stearic acid, which is generally considered to be non-reactive towards ozone, on the reaction kinetics as determined by neutron reflectometry measurements. Atmospheric aerosol can be extremely viscous. The kinetics of the reaction were found to be independent of the viscosity of the sub-phase below the monolayer over a range of moderate viscosities, eta/eta water = 1.0-7.2, demonstrating no involvement of aqueous sub-phase oxidants in the rate determining step. The kinetics of oxidation of monolayers of pure oleic acid were found to depend on the surface coverage with different behaviour observed above and below a surface coverage of oleic acid of similar to 1 x 10(18) molecule m(-2). Atmospheric aerosol are typically complex mixtures, and the presence of an additional compound in the monolayer that is inert to direct ozone oxidation, stearic acid, did not significantly change the reaction kinetics. It is demonstrated that oleic acid monolayers at the air-water interface do not leave any detectable material at the air-water interface, contradicting the previous work published in this journal which the authors now believe to be erroneous. The combined results presented here indicate that the kinetics, and thus the atmospheric chemical lifetime for unsaturated surface active materials at the air-water interface to loss by reaction with gas-phase ozone, can be considered to be independent of other materials present at either the air-water interface or in the aqueous sub-phase.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2020
National Category
Physical Chemistry Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:uu:diva-433636 (URN)10.1039/d0cp03934a (DOI)000603167900010 ()33367378 (PubMedID)
Funder
EU, Horizon 2020, 731096
Available from: 2021-02-01 Created: 2021-02-01 Last updated: 2021-02-01Bibliographically approved
Projects
Improving water purification and soil remediation with natural products [2011-07241_VR]; Uppsala UniversityCreating nanostructures using self-assembly of colloidal particles [2012-04382_VR]; Uppsala University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-8185-3272

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