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1,176 results on '"Ghadiri, M"'

252. Potential Agents for Treating Cystic Fibrosis: Cyclic Tetrapeptides That Restore Trafficking and Activity of Delta F508-CFTR

Author

Hutt, Darren M., Olsen, Christian Adam, Vickers, Chris J., Herman, David, Chalfant, Monica A., Montero, Ana, Leman, Luke J., Burkle, Renner, Maryanoff, Bruce E., Balch, William E., Ghadiri, M. Reza, Hutt, Darren M., Olsen, Christian Adam, Vickers, Chris J., Herman, David, Chalfant, Monica A., Montero, Ana, Leman, Luke J., Burkle, Renner, Maryanoff, Bruce E., Balch, William E., and Ghadiri, M. Reza

Published
2011

253. Triboelectric charging of powders: A review

Author

Matsusaka, S, 10219420, 90303867, Matsusaka, Shuji, Maruyama, H., Matsuyama, T., Ghadiri, M., Matsusaka, S, 10219420, 90303867, Matsusaka, Shuji, Maruyama, H., Matsuyama, T., and Ghadiri, M.

Abstract

Particles are often electrostatically charged by frictional contact during powder-handling operations. This phenomenon is called ‘triboelectric charging’ or ‘contact electrification’. The charged particles cause problems such as particle deposition and adhesion. In addition, if particles are excessively charged, an electrostatic discharge may occur, which can pose a risk of fire and explosion hazards; thus, to mitigate the adverse effects, it is important to elucidate the underlying triboelectric charging mechanisms. The electrostatics is, on the other hand, very useful in a number of applications that have been developed using the principles. In this review, the basic concepts and theories of charge transfer between solid surfaces are summarized, and chemical factors depending on materials and environmental effects are described. To theoretically analyze the process of particle charging, relevant models are discussed. Using the models, particle charging by repeated impacts on a wall is formulated. To experimentally evaluate particle charging, measurement and characterization methods are outlined. Furthermore, important applications and computer simulations are described.

Published
2010

254. Triboelectric charging of powders: A review

Author

Matsusaka, Shuji, 10219420, Matsusaka, S, Maruyama, H., Matsuyama, T., Ghadiri, M., Matsusaka, Shuji, 10219420, Matsusaka, S, Maruyama, H., Matsuyama, T., and Ghadiri, M.

Published
2010

258. Analysis of pulsating electric signals generated in gas–solids pipe flow

Author

Matsusaka, Shuji, 10219420, Fukuda, H., Sakura, Y., Masuda, H., Ghadiri, M., Matsusaka, Shuji, 10219420, Fukuda, H., Sakura, Y., Masuda, H., and Ghadiri, M.

Abstract

In gas–solids pipe flow, particles are electrostatically charged as a result of repeated impacts on the inner walls. When a section of the pipe made of metal is electrically isolated and the charge leakage to the ground is monitored, pulsating electric signals are detected. In the present work, these signals have been studied both experimentally and theoretically. Micrometer-sized alumina particles were dispersed through an ejector and continuously transported in dilute phase. The pipes used were 6 mm in inner diameter, and a pre-charging pipe and detection pipes were installed in the particle transport system. The pulsating electric signals were found to vary in a wide range from positive to negative. The variation of the electric signals was attributed to two electrostatic phenomena (i) the induced current caused by the transport of a cloud of charged particles and (ii) the particle charging caused by repeated impacts on the inner wall. Based on analyses of these phenomena, the total charge, transferred charge, and particle concentration of the cloud can be evaluated. Furthermore, the average velocity of the cloud flowing in the pipe can be obtained from the time interval between peak signals measured with a detection pipe or using a two-detection pipe system based on the correlation method.

Published
2008

260. Supramolecular design by covalent capture. Design of a peptide cylinder via hydrogen-bond-promoted intermolecular olefin metathesis

Author

Clark, Thomas D. and Ghadiri, M. Reza

Subjects
Hydrogen bonding -- Observations, Peptides -- Usage, Olefins -- Analysis, Chemistry
Abstract

The covalent capture process is effectively used for synthesizing a covalently stabilized beta-sheet-like peptide cylinder. A ring shaped peptide subunit is self-assembled to two thermodynamically stable antiparallel beta-sheet-like hydrogen-bonded cylindrical structures via hydrogen bonding interactions. The covalent capture involves the usage of hydrogen-bond-induced 38-member ring forming olefin metathesis in the presence of (Cy3P)2Cl2-Ru=CHCH=CPh2.

Published
1995

268. Potentially Prebiotic Synthesis of α-Amino Thioacids in Water.

Author

Leman, Luke J. and Ghadiri, M. Reza

Subjects
*THIOL synthesis, *AMINOACYLATION, *PREBIOTICS
Abstract

Although thioacids have been proposed as acylating agents and energy carriers in the context of prebiotic chemical evolution, there has been little exploration of their synthesis in an aqueous, abiotic setting. Here we report that α-amino thioacids are generated from α-amino acids in water in the presence of carbonyl sulfide (COS), a component of volcanic and deep sea vent emissions. Traces of thioacid are formed when amino acids react with COS alone in water, with the required sulfide presumably originating from COS decomposition. Higher yields of thioacid are observed when sulfide ions are added exogenously to the reactions. The proposed mechanism involves activation of the amino acid to an N-carboxyanhydride (NCA) mediated by COS. Our data shows that COS also catalyzes the hydrolysis of α-amino thioacids, so the observed yields are a net of thioacid synthesis and breakdown. Although the NCA has been a topic of research for decades, this is the first report to our knowledge of NCA-mediated thioacid formation in water. These findings broaden the scope of reactions mediated by COS, suggesting a mechanism by which peptide formation, phosphate activation and phosphorylation, and the syntheses of aminoacyl thioacids, could have shared a common pathway on the prebiotic Earth. [ABSTRACT FROM AUTHOR]

Published
2017
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270. Channel-mediated transport of glucose across lipid bilayers

Author

Granja, Juan R. and Ghadiri, M. Reza

Subjects
Bilayer lipid membranes -- Research, Biological transport -- Analysis, Glucose -- Physiological aspects, Chemistry
Abstract

Procedures used for the construction of transmembrane ion channels help design artificial transmembrane pore structure exhibiting efficient glucose transport activity across lipid bilayers. Molecular modeling reveals the necessity of the presence of an internal van der Waals pore diameter of greater than 9 angstroms for the transport of glucose via the cylindrical cavity of the tubular transmembrane structure. Kinetic studies reveal that glucose transport due to the addition of channel-forming peptide follows a first-order kinetics.

Published
1994

272. Nanoscale tubular ensembles with specified internal diameters. Design of a self-assembled nanotube with a 13-A pore

Author

Khazanovich, Nina, Granja, Juan R., McRee, Duncan E., Milligan, Ronald A., and Ghadiri, M. Reza

Subjects
Peptides -- Synthesis, Nanotechnology -- Usage, Spectrum analysis -- Observations, Chemistry
Abstract

Adjustment of peptide subunit ring size controls the internal diameter of a peptide nanotube. This technique is used to construct nanotubes with a uniform 13 A Van der Waals pore diameter from a 12-residue cyclic peptide structure. Various spectroscopic techniques and molecular modeling are used to confirm the tubular structure formation.

Published
1994

273. Electrostatics in powders - Preface

Author

Matsusaka, S, Matsusaka, Shuji, Masuda, H, Ghadiri, M, Matsusaka, S, Matsusaka, Shuji, Masuda, H, and Ghadiri, M

Published
2006

274. Electrostatics in powders - Preface

Author

Matsusaka, Shuji, 10219420, Matsusaka, S, Masuda, H, Ghadiri, M, Matsusaka, Shuji, 10219420, Matsusaka, S, Masuda, H, and Ghadiri, M

Published
2006

285. Potential Agents for Treating Cystic Fibrosis: Cyclic Tetrapeptides That Restore Trafficking and Activity of ΔF508-CFTR

Author

Hutt, Darren M., primary, Olsen, Christian A., additional, Vickers, Chris J., additional, Herman, David, additional, Chalfant, Monica A., additional, Montero, Ana, additional, Leman, Luke J., additional, Burkle, Renner, additional, Maryanoff, Bruce E., additional, Balch, William E., additional, and Ghadiri, M. Reza, additional

Published
2011
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