Search

Your search keyword '"Lewis, Richard J."' showing total 1,174 results
Start Over Author "Lewis, Richard J." Language english
1,174 results on '"Lewis, Richard J."'

7. Au–Pd separation enhances bimetallic catalysis of alcohol oxidation

Author

Huang, Xiaoyang, Akdim, Ouardia, Douthwaite, Mark, Wang, Kai, Zhao, Liang, Lewis, Richard J., Pattisson, Samuel, Daniel, Isaac T., Miedziak, Peter J., Shaw, Greg, Morgan, David J., Althahban, Sultan M., Davies, Thomas E., He, Qian, Wang, Fei, Fu, Jile, Bethell, Donald, McIntosh, Steven, Kiely, Christopher J., and Hutchings, Graham J.

Published
2022
Full Text
View/download PDF

17. A residue-free approach to water disinfection using catalytic in situ generation of reactive oxygen species

Author

Richards, Thomas, Harrhy, Jonathan H., Lewis, Richard J., Howe, Alexander G. R., Suldecki, Grzegorz M., Folli, Andrea, Morgan, David J., Davies, Thomas E., Loveridge, E. Joel, Crole, David A., Edwards, Jennifer K., Gaskin, Paul, Kiely, Christopher J., He, Qian, Murphy, Damien M., Maillard, Jean-Yves, Freakley, Simon J., and Hutchings, Graham J.

Published
2021
Full Text
View/download PDF

20. The application of Cs-exchanged tungstophosphoric acid as an additive in the direct synthesis of hydrogen peroxide and the use of Au-Pd/TS-1 in a one-pot approach to cyclohexanone oxime production

Author

Lewis, Richard J.

Subjects
547, QD Chemistry
Abstract

The work presented within this thesis can be separated into two distinct parts. The first investigates the direct synthesis of hydrogen peroxide from molecular hydrogen and oxygen using gold-palladium supported catalysts and caesium exchanged tungstophosphoric acid as an acidic additive. The direct synthesis of H2O2 presents an environmentally friendly alternative to the current industrial, anthraquinone process. However for the direct route to be viable a variety of issues must be addressed. Primarily catalytic selectivity towards H2O2 is a major concern for the majority of catalysts active for H2O2 synthesis, with the degradation of H2O2 through hydrogenation or decomposition reported for a number of catalysts within the literature. The use of acid either during catalyst preparation or as part of the reaction solution has previously been shown to improve selectivity towards H2O2. Furthermore acidic supports, including heteropolyacid, have been observed to produce catalysts with greater selectivity than those with a higher isoelectric point and in turn provide higher yields of H2O2. This work investigates the ability of caesium exchanged heteropolyacids to improve catalytic activity towards H2O2 when used in addition to Au-Pd supported catalysts, in particular 2.5 wt. % Au - 2.5 wt. Pd/TiO2. The second part of this work is concerned with the ammoximation of cyclohexanone to cyclohexanone oxime via the in-situ formation of H2O2, in a one-pot style process. The conditions associated with ammoximation of cyclohexanone that is the presence of elevated temperatures and basic conditions, are considered extremely harsh for H2O2 stability. The in-situ generation of H2O2 during the ammoximation of cyclohexanone to cyclohexanone oxime would yield significant reductions in overall costs of the ammoximation reaction. Primarily these costs are associated with the purchasing, transport, storage and dilution of H2O2. This work determines the feasibility of a one-pot ammoximation process via in-situ H2O2 formation. Firstly, reaction conditions are established for this process and following this the role of catalyst design in improving selectivity towards cyclohexanone oxime as well as cyclohexanone conversion for this reaction is studied.

Published
2016

23. Novel Scorpion Toxin ω-Buthitoxin-Hf1a Selectively Inhibits Calcium Influx via Ca V 3.3 and Ca V 3.2 and Alleviates Allodynia in a Mouse Model of Acute Postsurgical Pain.

Author

Wang, Dan, Herzig, Volker, Dekan, Zoltan, Rosengren, K. Johan, Payne, Colton D., Hasan, Md. Mahadhi, Zhuang, Jiajie, Bourinet, Emmanuel, Ragnarsson, Lotten, Alewood, Paul F., and Lewis, Richard J.

Subjects
SCORPION venom, POSTOPERATIVE pain, AMINO acid residues, LABORATORY mice, PEPTIDOMIMETICS, MEMBRANE proteins
Abstract

Venom peptides have evolved to target a wide range of membrane proteins through diverse mechanisms of action and structures, providing promising therapeutic leads for diseases, including pain, epilepsy, and cancer, as well as unique probes of ion channel structure-function. In this work, a high-throughput FLIPR window current screening assay on T-type CaV3.2 guided the isolation of a novel peptide named ω-Buthitoxin-Hf1a from scorpion Hottentotta franzwerneri crude venom. At only 10 amino acid residues with one disulfide bond, it is not only the smallest venom peptide known to target T-type CaVs but also the smallest structured scorpion venom peptide yet discovered. Synthetic Hf1a peptides were prepared with C-terminal amidation (Hf1a-NH2) or a free C-terminus (Hf1a-OH). Electrophysiological characterization revealed Hf1a-NH2 to be a concentration-dependent partial inhibitor of CaV3.2 (IC50 = 1.18 μM) and CaV3.3 (IC50 = 0.49 μM) depolarized currents but was ineffective at CaV3.1. Hf1a-OH did not show activity against any of the three T-type subtypes. Additionally, neither form showed activity against N-type CaV2.2 or L-type calcium channels. The three-dimensional structure of Hf1a-NH2 was determined using NMR spectroscopy and used in docking studies to predict its binding site at CaV3.2 and CaV3.3. As both CaV3.2 and CaV3.3 have been implicated in peripheral pain signaling, the analgesic potential of Hf1a-NH2 was explored in vivo in a mouse model of incision-induced acute post-surgical pain. Consistent with this role, Hf1a-NH2 produced antiallodynia in both mechanical and thermal pain. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

31. Discovery and Characterization of a Bicyclic Peptide (Bicycle) Binder to Thymic Stromal Lymphopoietin.

Author

Narjes, Frank, Edfeldt, Fredrik, Petersen, Jens, Öster, Linda, Hamblet, Corinne, Bird, James, Bold, Peter, Rae, Rebecca, Bäck, Elisabeth, Stomilovic, Stina, Zlatoidsky, Pavol, Svensson, Tor, Hidestål, Lotta, Kunalingam, Lavaniya, Shamovsky, Igor, De Maria, Leonardo, Gordon, Euan, Lewis, Richard J., Watcham, Sophie, and van Rietschoten, Katerine

Published
2024
Full Text
View/download PDF

44. A comparative study of palladium-gold and palladium-tin catalysts in the direct synthesis of H2O2.

Author

Kovačič, Dávid, Lewis, Richard J., Crombie, Caitlin M., Morgan, David J., Davies, Thomas E., López-Martín, Ángeles, Qin, Tian, Allen, Christopher S., Edwards, Jennifer. K., Chen, Liwei, Skjøth-Rasmussen, Martin Skov, Liu, Xi, and Hutchings, Graham J.

Subjects
*CATALYST synthesis, *SCRAP metals, *COMPARATIVE studies, *CATALYSTS, *DISPERSION (Chemistry)
Abstract

Herein we evaluate the promotive effect of Au and Sn incorporation into supported Pd nanoparticles for the direct synthesis of H2O2 from molecular H2 and O2. The introduction of both secondary metal modifiers was found to result in a significant enhancement in catalytic performance, although, in the case of the PdSn system, it was identified that relatively large quantities of the secondary metal were required to rival the activity observed over optimal Au-containing formulations, with the 0.25%Pd–2.25%Sn/TiO2 catalyst offering comparable H2O2 synthesis rates to the optimised 0.25%Pd–0.25%Au/TiO2 formulation. The introduction of Sn was found to considerably improve Pd dispersion, correlating with an improvement in selective H2 utilisation. Notably, the optimal PdSn catalyst identified in this work achieves superior H2O2 selectivities compared to the PdAu analogue and is able to rival the performance of state-of-the-art materials. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

45. A comparative study of palladium-gold and palladium-tin catalysts in the direct synthesis of H2O2.

Author

Kovačič, Dávid, Lewis, Richard J., Crombie, Caitlin M., Morgan, David J., Davies, Thomas E., López-Martín, Ángeles, Qin, Tian, Allen, Christopher S., Edwards, Jennifer. K., Chen, Liwei, Skjøth-Rasmussen, Martin Skov, Liu, Xi, and Hutchings, Graham J.

Subjects
CATALYST synthesis, SCRAP metals, COMPARATIVE studies, CATALYSTS, DISPERSION (Chemistry)
Abstract

Herein we evaluate the promotive effect of Au and Sn incorporation into supported Pd nanoparticles for the direct synthesis of H2O2 from molecular H2 and O2. The introduction of both secondary metal modifiers was found to result in a significant enhancement in catalytic performance, although, in the case of the PdSn system, it was identified that relatively large quantities of the secondary metal were required to rival the activity observed over optimal Au-containing formulations, with the 0.25%Pd–2.25%Sn/TiO2 catalyst offering comparable H2O2 synthesis rates to the optimised 0.25%Pd–0.25%Au/TiO2 formulation. The introduction of Sn was found to considerably improve Pd dispersion, correlating with an improvement in selective H2 utilisation. Notably, the optimal PdSn catalyst identified in this work achieves superior H2O2 selectivities compared to the PdAu analogue and is able to rival the performance of state-of-the-art materials. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

46. Structure-function and rational design of a spider toxin Ssp1a at human voltage-gated sodium channel subtypes.

Author

Dongol, Yashad, Wilson, David T., Daly, Norelle L., Cardoso, Fernanda C., and Lewis, Richard J.

Subjects
SPIDER venom, SODIUM channels, TOXINS, CONOTOXINS, SPIDERS, MOLECULAR docking, DRUG target
Abstract

The structure-function and optimization studies of NaV-inhibiting spider toxins have focused on developing selective inhibitors for peripheral pain-sensing NaV1.7. With several NaV subtypes emerging as potential therapeutic targets, structure-function analysis of NaV-inhibiting spider toxins at such subtypes is warranted. Using the recently discovered spider toxin Ssp1a, this study extends the structure-function relationships of NaV-inhibiting spider toxins beyond NaV1.7 to include the epilepsy target NaV1.2 and the pain target NaV1.3. Based on these results and docking studies, we designed analogues for improved potency and/or subtype-selectivity, with S7R-E18K-rSsp1a and N14D-P27R-rSsp1a identified as promising leads. S7R-E18K-rSsp1a increased the rSsp1a potency at these three NaV subtypes, especially at NaV1.3 (~10-fold), while N14D-P27R-rSsp1a enhanced NaV1.2/1.7 selectivity over NaV1.3. This study highlights the challenge of developing subtype-selective spider toxin inhibitors across multiple NaV subtypes that might offer a more effective therapeutic approach. The findings of this study provide a basis for further rational design of Ssp1a and related NaSpTx1 homologs targeting NaV1.2, NaV1.3 and/or NaV1.7 as research tools and therapeutic leads. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results