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Your search keyword '"SARTBAEVA, ASEL"' showing total 138 results
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138 results on '"SARTBAEVA, ASEL"'

1. Defective hierarchical porous copper-based metal-organic frameworks synthesised via facile acid etching strategy

Author

Doan, Huan V., Sartbaeva, Asel, Eloi, Jean-Charles, Davis, Sean, and Ting, Valeska P.

Subjects
Condensed Matter - Materials Science
Abstract

Introducing hierarchical pore structure to microporous materials such as metal-organic frameworks (MOFs) can be beneficial for reactions where the rate of reaction is limited by low rates of diffusion or high pressure drop. This advantageous pore structure can be obtained by defect formation, mostly via post-synthetic acid etching, which has been studied extensively on water-stable MOFs. Here we show that a water-unstable HKUST-1 MOF can also be modified in a corresponding manner by using phosphoric acid as a size-selective etching agent and a mixture of dimethyl sulfoxide and methanol as a dilute solvent. Interestingly, we demonstrate that the etching process which is time- and acidity- dependent, can result in formation of defective HKUST-1 with extra interconnected hexagonal macropores without compromising on the bulk crystallinity. These findings suggest an intelligent scalable synthetic method for formation of hierarchical porosity in MOFs that are prone to hydrolysis, for improved molecular accessibility and diffusion for catalysis., Comment: 14 pages, 8 figures

Published
2019

2. A solid approach to biopharmaceutical stabilisation

Author

Doekhie, Aswin, Dattani, Rajeev, Chen, Yun-Chu, Yang, Yi, Smith, Andrew, Silve, Alex P., Koumanov, Francoise, Edler, Karen J., Marchbank, Kevin J., Elsen, Jean van den, and Sartbaeva, Asel

Subjects
Physics - Biological Physics
Abstract

Ensilication is a technology we developed that can physically stabilise proteins in silica without use of a pre-formed particle matrix. Stabilisation is done by tailor fitting individual proteins with a silica coat using a modified sol-gel process. Biopharmaceuticals, for example, liquid-formulated vaccines with adjuvants, have poor thermal stability. Heating or freezing impairs their potency. As a result, there is an increase in the prevalence of vaccine-preventable diseases in low-income countries even when there are means to combat them. One of the root causes lies in the problematic vaccine cold-chain distribution. We believe that ensilication can improve vaccine availability by enabling transportation without refrigeration. Here, we show that ensilication stabilises tetanus toxoid C fragment (TTCF) and demonstrate that this material can be stored and transported at ambient temperature without compromising the immunogenic properties of TTCF in vivo. TTCF is a component of the diphtheria, tetanus and pertussis (DTP) vaccine. To further our understanding of the ensilication process, and its protective effect on proteins we have studied the formation of TTCF-silica nanoparticles via time-resolved Small Angle X-ray Scattering (SAXS). Our results reveal ensilication to be a staged diffusion-limited cluster aggregation (DLCA) type reaction, induced by the presence of TTCF protein at neutral pH. Analysis of scattering data indicates tailor fitting of TTCF protein. The experimental in vivo immunisation data confirms the retention of immunogenicity after release from silica. Our results suggest that we could utilise this technology for multicomponent vaccines, therapeutics or other biopharmaceuticals that are not compatible with lyophilisation., Comment: 4 figures, 9 pages

Published
2018
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3. Thermal Stabilisation of Lysozyme through Ensilication.

Author

Abdulkareem, Reveng A., Doekhie, Aswin, Fotaki, Nikoletta, Koumanov, Francoise, Dodson, Charlotte A., and Sartbaeva, Asel

Subjects
BIOCOMPATIBILITY, PROTEIN stability, THERAPEUTIC use of proteins, ENZYMES, PROTEINS
Abstract

Protein therapeutics, vaccines, and other commercial products are often sensitive to environmental factors, such as temperature and long-term storage. In many cases, long-term protein stability is achieved by refrigeration or freezing. One alternative is the encapsulation of the protein cargo within an inert silica matrix (ensilication) and storage or transport at room temperature as a dry powder. In this paper, we test the effect of three commonly used biological buffers on the ensilication, storage, and desilication of the enzyme lysozyme. We show that ensilication protects lysozyme from heat (100 °C for 1 h) and during storage (18 months at room temperature). The choice of ensilication buffer has little effect on the activity of lysozyme after desilication. Our results provide confidence in the continued pursuit of ensilication as a methodology for protein stabilisation and in its compatibility with biological buffers. [ABSTRACT FROM AUTHOR]

Published
2024
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21. A Novel In Situ High‐Temperature Magnetometry Method for Radiofrequency Heating Applications.

Author

Noble, Jonathan P. P., Bending, Simon J., Sartbaeva, Asel, Muxworthy, Adrian R., and Hill, Alfred K.

Subjects
RADIO frequency, MAGNETIC hysteresis, RAYLEIGH scattering, MAGNETIC flux density, HYSTERESIS loop
Abstract

Radiofrequency heating of magnetic particles promises highly efficient and direct heating of catalytic reactors for coupling of low carbon electricity with energy intensive chemical transformations. In this work, a novel real‐time and in situ magnetometry method is developed to measure minor and major hysteresis loops of soft magnetic nanopowders. It is applied to measure the magnetic properties and hysteresis power absorption of magnetite and maghemite powders up to 500 °C. An arctangent model for saturation magnetization is adapted for minor hysteresis loops. It produces an excellent fit for hysteresis loop power across field strengths up to 18.5 kA m−1 and allows prediction of heating power, remanence, and susceptibility. Samples of magnetite and maghemite are shown to heat rapidly from room temperature at more than 25 °C s−1, with maghemite giving the strongest heating response. The peak heating power occurs at the transition beyond the ellipsoidal Rayleigh law region. These findings suggest that the properties of magnetic powders, coupled with variable magnetic field strengths and frequencies, can be tuned to optimize the heating power for a variety of applications. [ABSTRACT FROM AUTHOR]

Published
2022
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22. Formation And Characterization Of ZnS Nanoclusters In The Pore Channels Of Mordenite Zeolite

Author

Pirzada Afridi, Leung, Ka Ming, France, Liam, Kuznetsov, Vladimir L., Edwards, Peter P., and Sartbaeva, Asel

Subjects
nanoclusters, Zeolite,Nanoclusters,Ion Exchange,Structure,Diffraction,Microscopy, ion exchange, structure, zeolite, diffraction, microscopy
Abstract

Mordenite zeolite was synthesized without organic structure directing agents. We used ion exchange to create the zinc sulphide nano-clusters inside the zeolite framework. The as-synthesised (Na-MOR zeolite) and exchanged samples (Zn-MOR, ZnS-MOR zeolites) were characterised by X-ray powder diffraction (XRPD), solid state magic angle spinning nuclear magnetic resonance (MAS NMR), energy- dispersive X-ray (EDX) elemental analysis, Brunauer-Emmett-Teller (BET) surface area analysis, and transmission electron microscopy (TEM). PXRD shows that exchange does not affect the zeolite framework, a a slight increase in the unit cell parameters from Na-MOR to ZnS-MOR is observed. The successful incorporation of Zn2+into the MOR framework is confirmed by23Na NMR. EDX, BET, and TEM analyses also provide evidences for the formation of ZnS nano-clusters.

Published
2019
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23. Figures showing the raw and refined data from Pressure-induced symmetry changes in body-centred cubic zeolites

Author

Nearchou, Antony, Mero-Lee U. Cornelius, Zöe L. Jones, I. E. Collings, Wells, Stephen A., Raithby, Paul R., and Sartbaeva, Asel

Abstract

Previous work has shown a strong correlation between zeolite framework flexibility and the nature of structural symmetry and phase transitions. However, there is little experimental data regarding this relationship, in addition to how flexibility can be connected to the synthesis of these open-framework materials. This is of interest for the synthesis of novel zeolites, which require organic additives to permutate the resulting geometry and symmetry of the framework. Here, we have used high-pressure powder X-ray diffraction to study the three zeolites: Na-X, RHO and ZK-5, which can all be prepared using 18-crown-6 ether as an organic additive. We observe significant differences in how the occluded 18-crown-6 ether influences the framework flexibility—this being dependant on the geometry of the framework. We use these differences as an indicator to define the role of 18-crown-6 ether during zeolite crystallization. Furthermore, in conjunction with previous work, we predict that pressure-induced symmetry transitions are intrinsic to body-centred cubic zeolites. The high symmetry yields fewer degrees of freedom, meaning it is energetically favourable to lower the symmetry to facilitate further compression.

Published
2019
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24. Utilization of Staphylococcal Immune Evasion Protein Sbi as a Novel Vaccine Adjuvant

Author

Yang, Yi, Back, Catherine R., Sartbaeva, Asel, Watts, Andrew G., Marchbank, Kevin J., van den Elsen, Jean M. H., Gräwert, Melissa A., Wahid, Ayla A., Denton, Harriet, Kildani, Rebecca, Paulin, Joshua, Wörner, Kristin, Kaiser, Wolgang, and Svergun, Dmitri I.

Subjects
Models, Molecular, lcsh:Immunologic diseases. Allergy, Protein Conformation, Recombinant Fusion Proteins, Staphylococcus, Immunology, Complement, chemical and pharmacologic phenomena, Mice, Structure-Activity Relationship, SDG 3 - Good Health and Well-being, Adjuvants, Immunologic, Bacterial Proteins, adjuvant, vaccine, Animals, Immunology and Allergy, complement, ddc:610, Adjuvant, Original Research, immune evasion, Mice, Knockout, Antigens, Bacterial, Immune evasion, Staphylococcal Vaccines, Staphylococcal Infections, Disease Models, Animal, Staphycoccus aureus, Immunization, Carrier Proteins, lcsh:RC581-607, Vaccine, Acyltransferases
Abstract

Co-ligation of the B cell antigen receptor with complement receptor 2 on B-cells via a C3d-opsonised antigen complex significantly lowers the threshold required for B cell activation. Consequently, fusions of antigens with C3d polymers have shown great potential in vaccine design. However, these linear arrays of C3d multimers do not mimic the natural opsonisation of antigens with C3d. Here we investigate the potential of using the unique complement activating characteristics of Staphylococcal immune-evasion protein Sbi to develop a pro-vaccine approach that spontaneously coats antigenswith C3 degradation products in a natural way. We show that Sbi rapidly triggers the alternative complement pathway through recruitment of complement regulators, forming tripartite complexes that act as competitive antagonists of factor H, resulting in enhanced complement consumption. These functional results are corroborated by the structure of the complement activating Sbi-III-IV:C3d:FHR-1 complex. Finally, we demonstrate that Sbi, fused with Mycobacterium tuberculosis antigen Ag85b, causes efficient opsonisation with C3 fragments, thereby enhancing the immune responsesignificantly beyond that of Ag85b alone, providing proof of concept for our pro-vaccine approach.

Published
2019

32. Controlled Formation of Hierarchical Metal-Organic Frameworks Using CO2-Expanded Solvent Systems

Author

Doan, Huan V., Fang, Yanan, Yao, Bingqing, Dong, Zhili, White, Timothy J., Sartbaeva, Asel, Hintermair, Ulrich, and Ting, Valeska P.

Subjects
Chemistry(all), Renewable Energy, Sustainability and the Environment, Metal-organic frameworks, HKUST-1, Expanded liquid phases, Hierarchical porosity, Chemical Engineering(all), Environmental Chemistry, SDG 7 - Affordable and Clean Energy, Supercritical CO
Abstract

It is shown that a crystalline metal-organic framework (HKUST-1) can be rapidly synthesized from a DMSO/MeOH solution with greatly reduced amounts of organic solvents using a supercritical CO2 (scCO2) solvent expansion technique. The precursor solution is stable for months under ambient conditions, and CO2-driven MOF (metal-organic framework) crystallization is achieved under mild conditions (40 °C, 40-100 bar) with excellent reproducibility. As the degree of liquid-phase expansion drives MOF nucleation and growth, the crystallite size and overall yield can be tuned by adjusting the CO2 pressure. Furthermore, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and gas sorption analyses showed that, in the presence of scCO2, HKUST-1 crystallites with a hierarchical pore structure are generated through a postcrystallization etching process. These findings demonstrate that scCO2 is a time- and material-efficient route to MOF synthesis with a high level of control over the crystallization process for accessing tailored material properties.

Published
2017

46. Hydrogen Economy

Author

Wells, Stephen A., primary, Sartbaeva, Asel, additional, Kuznetsov, Vladimir L., additional, and Edwards, Peter P., additional

Published
2011
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