Synthesis and photophysical properties of conformationally fixed tricarbocyanines with phosphonate groups

A method for the synthesis of a series of symmetric and asymmetric conformationally fixed tricarbocyanines was developed based on benzоindolenine containing ethyl phosphonate and diethyl phosphonate groups in the linker at the quaternary nitrogen atom of the indolenine fragment. The polymethine chain meso position was modified by nucleophilic substitution of chlorine with O- and N-nucleophiles. Their absorption and fluorescence spectra were recorded, the possibility of further use of phosphonate-substituted tricarbocyanines as biomarkers was demonstrated. The dark cytotoxicity of synthesized compounds was studied, the possibility of their accumulation in HCT116, MCF7 cancer cells was shown.     

Comparative performance of tripole and quadrupole ion guides at elevated pressure

This study presents the first practical demonstration of an operational tripole ion guide. The transmission was measured for both the tripole and quadrupole ion guides at 1 Torr pressure. It was found that the quadrupole provides 2.5-3 times better ion transmission efficiency. Two different electric schemes for driving the tripole were tested. Similar transmission characteristics were obtained in both cases. A brief analysis of the tripole performance and ways to improve it is presented.     

Modeling of ion processes in atmospheric pressure matrix-assisted laser desorption/ionisation

Atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) has proven a convenient and rapid method for ion production in the mass spectrometric analysis of biomolecules. This technique, like other atmospheric pressure ionization methods, suffers from ion loss during ion transmission from the atmosphere into the vacuum of the mass spectrometer. In this work, a simple model describing ion formation and ion motion towards the inlet capillary of the mass spectrometer is described. Both the gas flow and electric field near the MALDI plate were numerically calculated using the boundary element method (BEM). The ions were moving along with the gas flow and drifting in the electric field in accordance with their ion mobility properties. The ion signal dependence on an electric field strength obtained in the proposed model correlates well with experimental results.     

昆虫信息素研究III: 拟蚜虫警戒素的研究

合成了一系列碳数为十五和十四的倍半萜类蚜虫警戒素,并进行了生物活性测定,从中筛选有效化合物.     

Status of the Baikal neutrino project

The status of the Baikal neutrino experiment is briefly reviewed and the results of the search for the natural flux of high-energy neutrinos are reported.     

Monitoring the Dynamics of Phase Separation in a Polymer Blend by Confocal Imaging and Fluorescence Correlation Spectroscopy

The phase separation of the polymer blend polystyrene/poly(methyl phenyl siloxane) (PS/PMPS) is studied in situ by laser scanning confocal microscopy (LSCM) and by fluorescence correlation spectroscopy (FCS) at macroscopic and microscopic length scales, respectively. It is shown for the first time that FCS when combined with LSCM can provide independent information on the local concentration within the phase‐separated domains as well as the interfacial width.     

Spectral and luminescence properties of derivatives of 2-aryl[9,10]phenanthroxazole

Certain 2-aryl derivatives of [9,10]phenanthroxazole have been synthesized and their spectral and luminescence properties have been investigated. It has been shown that the introduction of acceptor substituents into the para position of the 2 -phenyl radical changes the nature of the fluorescence state, resulting in a nearly two-fold increase of the rate constant of fluorescence emission and a 50% increase of the quantum yield of fluorescence. Special features of the spectral and luminescence properties have been examined for derivatives with an intramolecular hydrogen bond (aryl = o-hydroxyphenyl) and with considerable steric hindrance (aryl = 9-anthryl).Khar'kov State University, Khar'kov 310077. Institute of Single Crystals, National Academy of Sciences of the Ukraine, Khar'kov 310001. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 558–566, April, 1995. Original article submitted February 23, 1994.     

羧甲基纤维素钠水凝胶的制备及其生物降解性研究

用羧甲基纤维素钠(CMC—Na)制得了含水量高达98％的水凝胶，考察了防腐剂、交联剂、无机态氮素、有机态氮素、碳水化合物的加入量以及环境中pH值等因素对生物降解性的影响。结果表明：制备条件不同，水凝胶的生物降解性不同；环境中一定量铵根离子的存在有利于水凝胶的生物降解；在pH=5．2的环境中纤维素酶活性最高，降解程度最大。     

Solvatofluorochromic properties of sulfonyl fluoride derivatives of 5-aryl(heteroaryl)-2-phenyl-1,3,4-oxadiazole, promising fluorescent probes

The spectral characteristics of seven 5-aryl(heteroaryl)-2-phenyl-1,3,4-oxadiazole derivatives, containing an expressed electron-accepting grouping such as sulfonyl fluoride or sulfonyldifluoromethane in the para position of the phenyl substituent, have been investigated in solvents of various polarity. The insignificant effect of the n^* levels of the SO₂X grouping on the fluorescence properties of the compounds studied was established, as a result of which they are highly effective organic luminophors in the near ultraviolet and violet spectral ranges. The presence was shown of a significant solvatochromic effect exerted particularly clearly in derivatives with electron-donating groups in the 5-aryl substituent. As a result of this, the compounds indicated may be recommended for use as fluorescent probes in medicine and biology. Adiabatic flattening in the excited state of the sterically hindered methoxy derivative and the formation of a TICT state are considered, leading to quenching of the fluorescence of dimethylamino derivatives in media of high polarity.Kharkov State University, Kharkov 310077. Institute of Monocrystals, Academy of Sciences of the Ukraine, Kharkov 310001. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 988–994, July, 1997.     

Specifics of adsorption and chemical processes on the surface of gamma-irradiated vanadium dioxide

The effect of γ-irradiation on the electrophysical properties and processes of thermal desorption of water from the surface of vanadium oxides V₂O₃-VO_2?δ-VO_2+δ-V₂O₅ were studied by the thermal analysis and electric conductivity techniques. It was shown that the amount of adsorbed water on the surface and the phase composition of the surface changed under exposure to low doses. The observed effects for vanadium oxides as semiconductors were correlated with analogous processes for alumina as a dielectric. It was found that the surface conductivity in irradiated VO_2?δ samples during the chemical reaction of ethanol with benzoic acid adsorbed after irradiation was substantially higher than that in their unirradiated counterparts. It was assumed that irradiation enhances the metal-semiconductor phase transition on the VO_2?δ surface during the chemical reaction.