Low-temperature phase separation of a binary liquid mixture in porous materials studied by cryoporometry and pulsed-field-gradient NMR

The low-temperature liquid-liquid phase separation of the partially miscible hexane-nitrobenzene mixture imbibed in porous glasses of different pore sizes from 7 to 130 nm has been studied using 1H NMR (nuclear magnetic resonance) cryoporometry and pulse field gradient NMR methods. The mixture was quenched below both its upper critical solution temperature (T cr) and the freezing point of nitrobenzene. The size distribution of frozen nitrobenzene domains was derived through their melting point suppression according to the Gibbs-Thompson relation. The obtained data reveal small initial droplets of nitrobenzene surrounded by hexane, which are created as the temperature is decreased below Tcr and which thereafter coalesce by a droplet-diffusion mechanism. The inter-relation between the pore size and the found size distribution and shapes of nitrobenzene domains is discussed, as well as several aspects of molecular self-diffusion. © 2002 The American Physical Society

Liquid-liquid phase separation in micropores

Phase separation of binary liquids with an upper critical temperature in porous materials is studied by 1H NMR cryoporometry and cross-relaxation spectroscopy and by 15N NMR spectroscopy. The first method provides domain size distributions of the separating minority component while the other ones verify the segregation of the two liquids on molecular level. We find that metastable structures are formed manifested by bimodal domain size distributions. The kinetic arrest of domain growth may be imposed upon by bottlenecks in the porous structure that block diffusion of entire droplets. Practical applications, if one of the liquid components is polymerized, include mobile polymer particles trapped in porous matrix that can serve, e.g., as filters with microscopically amphiphilic pathways. © 2003 Elsevier B.V. All rights reserved

Dithiophosphorylation of racemic and enantiomerically pure 1-phenylethanamines

N,N′-Bis[(RS)-, (S)-, and (R)-1-phenylethyl]phosphorodiamidodithioic acids were synthesized by reactions of racemic and enantiomerically pure 1-phenylethanamines with tetraphosphorus decasulfide. © 2014 Pleiades Publishing, Ltd

A Massive Jet Ejection Event from the Microquasar SS 433 Accompanying Rapid X-Ray Variability

Microquasars occasionally exhibit massive jet ejections which are distinct from the continuous or quasi-continuous weak jet ejections. Because those massive jet ejections are rare and short events, they have hardly been observed in X-ray so far. In this paper, the first X-ray observation of a massive jet ejection from the microquasar SS 433 with the Rossi X-ray Timing Explorer (RXTE) is reported. SS 433 undergoing a massive ejection event shows a variety of new phenomena including a QPO-like feature near 0.1 Hz, rapid time variability, and shot-like activities. The shot-like activity may be caused by the formation of a small plasma bullet. A massive jet may be consist of thousands of those plasma bullets ejected from the binary system. The size, mass, internal energy, and kinetic energy of the bullets and the massive jet are estimated.Comment: 21 pages including 5 figures, submitted to Ap

Performance of Waterborne Polyurethanes in Inhibition of Gas Hydrate Formation and Corrosion: Influence of Hydrophobic Fragments

The design of new dual-function inhibitors simultaneously preventing hydrate formation and corrosion is a relevant issue for the oil and gas industry. The structure-property relationship for a promising class of hybrid inhibitors based on waterborne polyurethanes (WPU) was studied in this work. Variation of diethanolamines differing in the size and branching of N-substituents (methyl, n-butyl, and tert-butyl), as well as the amount of these groups, allowed the structure of polymer molecules to be preset during their synthesis. To assess the hydrate and corrosion inhibition efficiency of developed reagents pressurized rocking cells, electrochemistry and weight-loss techniques were used. A distinct effect of these variables altering the hydrophobicity of obtained compounds on their target properties was revealed. Polymers with increased content of diethanolamine fragments with n- or tert-butyl as N-substituent (WPU-6 and WPU-7, respectively) worked as dual-function inhibitors, showing nearly the same efficiency as commercial ones at low concentration (0.25 wt%), with the branched one (tert-butyl; WPU-7) turning out to be more effective as a corrosion inhibitor. Commercial kinetic hydrate inhibitor Luvicap 55 W and corrosion inhibitor Armohib CI-28 were taken as reference samples. Preliminary study reveals that WPU-6 and WPU-7 polyurethanes as well as Luvicap 55 W are all poorly biodegradable compounds; BODt/CODcr (ratio of Biochemical oxygen demand and Chemical oxygen demand) value is 0.234 and 0.294 for WPU-6 and WPU-7, respectively, compared to 0.251 for commercial kinetic hydrate inhibitor Luvicap 55 W. Since the obtained polyurethanes have a bifunctional effect and operate at low enough concentrations, their employment is expected to reduce both operating costs and environmental impact.publishedVersio

ОЦЕНКА ЦИТОТОКСИЧНОСТИ ТРИХОТЕЦЕНА FUSARIUM SP. НА ЛИНИЮ РАКА МОЛОЧНОЙ ЖЕЛЕЗЫ IN VITRO

trichothecenes and their derivatives have recently attracted much attention of researchers with respect of their potential role in medicine, including for the treatment of different types of cancer. The purpose of the study was to investigate the cytotoxic effect of Fusarium trichothecene on human breast cancer cells,  human skin fibroblasts and embryonic kidney cells in vitro. Material and methods. Based on the Mtt assay, the cytotoxic effect of trichothecene on cell cultures was determined. Evaluation of morphological changes in cell cultures under the influence of trichothecene was performed by light microscopy. Results. Fusarium trichothecene was found to exhibit a dose-dependent toxic effect on cell lines in the range 1 nM to 1000 nM. the most pronounced cytotoxic effect of trichothecene was observed in human breast cancer cell line (IС50 94.72 ± 4.1 нМ). Lower doses of trichothecene led to a change in the size, shape of human breast cancer cells, human skin fibroblasts and embryonic kidney cells, and loss of contact between them and their isolation. the degradation of cell membranes, formation of unformed cell aggregates and fragments were observed in higher doses of trichothecene. Conclusion. Fusarium trichothecen is a biologically active compound and is less toxic to the normal than to the cancer cell lines, therefore, further studies of this agent are needed.В последнее время трихотеценовые соединения и их производные привлекают внимание исследователей в связи с их потенциальной возможностью применения в медицине, в том числе для лечения различных видов рака. Цель исследования – изучение цитотоксического действия трихотецена Fusarium sp. в отношении линий опухолевых клеток рака молочной железы, нормальных клеток фибробластов кожи и почек эмбриона человека in vitro. Материал и методы. С использованием общепринятого метода МТТ-теста проводилось определение цитотоксического действия трихотецена в отношении исследуемых культур клеток. Оценку изменения в морфологии клеток под воздействием трихотецена проводили методом световой микроскопии. Результаты. Было обнаружено, что трихотецен Fusarium sp. в диапазоне концентрации 1–1000 нM проявлял дозозависимое токсическое действие в отношении исследуемых линий клеток. Наиболее выраженное цитотоксическое действие трихотецена наблюдали при его действии на линию опухолевых клеток молочной железы (IС50 94,72 ± 4,1 нМ). Совместная инкубация трихотецена с линиями клеток рака молочной железы, клеток фибробластов кожи и почек эмбриона человека в более низких дозах приводила к изменению размеров, формы клеток, потере контактов между ними и их обособлению. При более высоких дозах трихотецена наблюдалась деградация мембран, образование неоформленных клеточных агрегатов и фрагментов (апоптозных тел). Заключение. Трихотецен Fusarium sp. обладает биологически активным потенциалом и является менее токсичным по отношению к нормальным клеткам человека по сравнению с опухолевыми, поэтому его целесообразно в дальнейшем исследовать как возможного противоопухолевого агента

Quantifying the Effects of Elastic Collisions and Non-Covalent Binding on Glutamate Receptor Trafficking in the Post-Synaptic Density

One mechanism of information storage in neurons is believed to be determined by the strength of synaptic contacts. The strength of an excitatory synapse is partially due to the concentration of a particular type of ionotropic glutamate receptor (AMPAR) in the post-synaptic density (PSD). AMPAR concentration in the PSD has to be plastic, to allow the storage of new memories; but it also has to be stable to preserve important information. Although much is known about the molecular identity of synapses, the biophysical mechanisms by which AMPAR can enter, leave and remain in the synapse are unclear. We used Monte Carlo simulations to determine the influence of PSD structure and activity in maintaining homeostatic concentrations of AMPARs in the synapse. We found that, the high concentration and excluded volume caused by PSD molecules result in molecular crowding. Diffusion of AMPAR in the PSD under such conditions is anomalous. Anomalous diffusion of AMPAR results in retention of these receptors inside the PSD for periods ranging from minutes to several hours in the absence of strong binding of receptors to PSD molecules. Trapping of receptors in the PSD by crowding effects was very sensitive to the concentration of PSD molecules, showing a switch-like behavior for retention of receptors. Non-covalent binding of AMPAR to anchored PSD molecules allowed the synapse to become well-mixed, resulting in normal diffusion of AMPAR. Binding also allowed the exchange of receptors in and out of the PSD. We propose that molecular crowding is an important biophysical mechanism to maintain homeostatic synaptic concentrations of AMPARs in the PSD without the need of energetically expensive biochemical reactions. In this context, binding of AMPAR with PSD molecules could collaborate with crowding to maintain synaptic homeostasis but could also allow synaptic plasticity by increasing the exchange of these receptors with the surrounding extra-synaptic membrane

4-ethylsulphonylnaphthalene-1-sulphonamide (hpa).

The low-temperature liquid-liquid phase separation of the partially miscible hexane-nitrobenzene mixture imbibed in porous glasses of different pore sizes from 7 to 130 nm has been studied using 1H NMR (nuclear magnetic resonance) cryoporometry and pulse field gradient NMR methods. The mixture was quenched below both its upper critical solution temperature (T cr) and the freezing point of nitrobenzene. The size distribution of frozen nitrobenzene domains was derived through their melting point suppression according to the Gibbs-Thompson relation. The obtained data reveal small initial droplets of nitrobenzene surrounded by hexane, which are created as the temperature is decreased below Tcr and which thereafter coalesce by a droplet-diffusion mechanism. The inter-relation between the pore size and the found size distribution and shapes of nitrobenzene domains is discussed, as well as several aspects of molecular self-diffusion. © 2002 The American Physical Society

Low-temperature phase separation of a binary liquid mixture in porous materials studied by cryoporometry and pulsed-field-gradient NMR

The low-temperature liquid-liquid phase separation of the partially miscible hexane-nitrobenzene mixture imbibed in porous glasses of different pore sizes from 7 to 130 nm has been studied using 1H NMR (nuclear magnetic resonance) cryoporometry and pulse field gradient NMR methods. The mixture was quenched below both its upper critical solution temperature (T cr) and the freezing point of nitrobenzene. The size distribution of frozen nitrobenzene domains was derived through their melting point suppression according to the Gibbs-Thompson relation. The obtained data reveal small initial droplets of nitrobenzene surrounded by hexane, which are created as the temperature is decreased below Tcr and which thereafter coalesce by a droplet-diffusion mechanism. The inter-relation between the pore size and the found size distribution and shapes of nitrobenzene domains is discussed, as well as several aspects of molecular self-diffusion. © 2002 The American Physical Society