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101.
102.
A. V. Filippov A. G. Zagorodny A. I. Momot A. F. Pal A. N. Starostin 《Journal of Experimental and Theoretical Physics》2007,104(1):147-161
An asymptotic theory for the screening of the electric field of a dust particle or a spherical probe in a plasma with an external steady and/or internal (proportional to the electron density) gas ionization source has been developed for the first time. It has been established that the screening of the charge of a spherical body adsorbing the charge of the incident plasma particles is described by a superposition of two exponentials with different screening constants. The two exponentials are retained even in the absence of nonequilibrium fluxes on the macroparticle and only in the special case of an isothermal plasma does the screening become Debye one. The screening length is determined by the ratio of the electron-ion, βei, and Langevin, βL = 4πeμi (where μi is the ion mobility), recombination coefficients. If βL ? βei, then it is much larger than the electron Debye length. The ions in an isothermal plasma have been found to give the same contribution to the screening as the electrons if the electron-ion recombination coefficient exceeds the Langevin ion recombination coefficient by a factor of 2 or more, βei ≥ 2βL. The Vlasov equation is used to analyze the asymptotic behavior of the macroparticle potential in a collisionless plasma. 相似文献
103.
Temporins are short (10–13 amino acids) and linear antimicrobial peptides first isolated from the skin of the European red
frog, Rana temporaria, and are effective against Gram-positive bacteria and Candida albicans. Similarly to other antimicrobial peptides, the association of temporins to lipid membranes has been concluded to underlie
their antimicrobial effects. Accordingly, a detailed understanding of their interactions with phospholipids is needed. We
conjugated a fluorophore (Texas Red) to a Cys containing derivative of temporin B (temB) and investigated its binding to liposomes
by fluorescence spectroscopy. Circular dichroic spectra for the Cys-mutant recorded in the absence and in the presence of
phospholipids were essentially similar to those for temB. A blue shift in the emission spectra and diminished quenching by
ferrocyanide (FCN) of Texas Red labeled temporin B (TRC-temB) were seen in the presence of liposomes. Both of these changes
can be attributed to the insertion of the Texas Red into the hydrophobic region of the bilayer. Resonance energy transfer,
steady state anisotropy, and fluorescence lifetimes further demonstrate the interaction of TRC-temB with liposomes to be enhanced
by negatively charged phospholipids. Instead, cholesterol attenuates the association of TRC-temB with membranes. The interactions
between TRC-temB and liposomes of varying negative surface charge are driven by electrostatics as well as hydrophobicity.
Similarly to native temporin B also TRC-temB forms amyloid type fibers in the presence of negatively charged liposomes. This
property is likely to relate to the cytotoxic activity of this peptide. 相似文献
104.
Gabriella Kervefors Kumar Bhaskar Pal Gergely L. Tolnai Mukul Mahanti Hakon Leffler Ulf J. Nilsson Berit Olofsson 《Helvetica chimica acta》2021,104(2):e2000220
β-Galactose derivatives have recently been reported to selectively inhibit galectin-3, and a library of O3-arylated galactosides with varying substitution patterns was designed to study such inhibitions further. The O3-arylated galactosides were synthesized using diaryliodonium salts under mild and transition metal free conditions, providing the target products in moderate to good yields. An O3-trifluoroethylated galactoside was also synthesized using iodonium salt chemistry. Azido-substituted products were subsequently transformed into the corresponding triazoles. After deprotection, a selection of galactoside derivatives were evaluated for inhibitory potencies against galectins-1, 3, 4 N (N-terminal domain), 4 C (C-terminal domain), 7, 8 N, 8 C, 9 N, and 9 C and one compound with promising affinity and selectivity for both the N- and C-terminal domain of galectin-9 was discovered. 相似文献
105.
Dattatraya N. Bhangare Rohit G. Shinde Pushpalata D. Pawar Milind D. Nikalje Mahendra N. Lokhande 《Journal of heterocyclic chemistry》2021,58(9):1878-1882
This method involves the direct asymmetric aldol reaction of (−)-menthyl isothiocyanatoacetate 5 with a variety of substituted aromatic aldehydes, which offers a convenient method for the synthesis of intermediate containing biologically relevant α-amino β-hydroxyl groups in oxazolidine ring. In this methodology, the products show remarkable diastereoselectivity using Sc(OTf)3 as a catalyst and easily accessible (−)-menthol as a chiral auxiliary. This approach includes some important aspects such as mild reaction conditions, high yields, and excellent diastereoselectivity with a number of substituted aromatic aldehydes. The optimization and effect of different catalysts were studied at different reaction conditions and it is found that Sc(OTf)3 shows excellent diastereoselectivity at −45°C. 相似文献
106.
107.
108.
G. G. Midyana R. G. Makitra E. Ya. Pal’chikova 《Russian Journal of General Chemistry》2014,84(1):22-24
Rate constant of chloroacetic acid alkaline hydrolysis in the mixed aqueous-organic solvents depends on the organic co-solvent nucleophilic solvation; however, the effect of the medium polarity on the rate constant is not clear. The rate constant can be reasonably estimated with a multi-parameter equation accounting for the organic co-solvent basicity as well as its density of cohesion energy and molar volume. 相似文献
109.
Sharmistha Pal B. N. Roopa Khalid Abu Sulur G. Manjunath Sudhir Nambiar 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2261-2268
Thermal techniques, differential scanning calorimetry (DSC), and hot stage microscopy (HSM) have been used to study the interactions between furosemide and caffeine that are known to form a 1:1 cocrystal. This system has been used as an example to study the probable mechanism of cocrystal formation when the individual components, which are polymorphic, are heated. The study indicates that the phase transition of the low temperature stable polymorph of furosemide initiates cocrystal formation. This result suggests increased mass transfer rate can trigger cocrystal formation. The binary phase diagram (composition–temperature plots) of furosemide–cocrystal–caffeine system was determined from the DSC curves. The results imply that the cocrystal forms eutectic with caffeine but not with furosemide. This study has thus exemplified the use of DSC in understanding binary phase system where the two components form a cocrystal. 相似文献
110.
Confinement of CuII–Phthalocyanine in a Bioinspired Hybrid Nanoparticle‐Assembled Structure Yields Selective and Stable Epoxidation Catalysts
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Joydeb Manna Arlin Jose Amali Dr. Rohit Kumar Rana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8453-8457
Herein, we demonstrate that a bioinspired assembly of silica nanoparticles with polyamines as structure‐directing agents similar to that known for the biosilicification of diatoms can pave the way for the efficient encapsulation of sulfonated copper–phthalocyanine in a hybrid microcapsule structure, in which the organic component provides a capable environment for its catalytic activity in epoxidation reactions and the nanoassembled structure imparts stability. 相似文献