C‐acylation of electron‐rich heterocyclic compounds with Kirsanov isocyanate

Pyrroles, indoles, indolizines, and 2‐methylfuran are vigorously C‐acylated with isocyanatophosphoryl dichloride. The resulting heteroaryl‐substituted isocyanatophosphoryl dichlorides provide a convenient access to a variety of products.© 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 343–348, 1999     

Dynamic mechanical behaviour of styrene/butadiene copolymers and their blends

The dynamic mechanical behaviour of high impact polystyrene (PS-HI), styrene/butadiene/styrene block copolymer (SBS) and PS-HI + SBS blends were investigated. Dynamic mechanical analysis (DMA) was performed in the temperature range −100°C to 100°C. The primary viscoelastic functions were determined. The copolymers PS-HI and SBS as well as PS-HI+SBS blends were investigated in creep-fatigue regime and relaxation at temperatures 25, 30, 35, 40 and 45°C. Dynamic mechanical behavior of PS-HI, SBS and PS-HI + SBS blends depends on the copolymer and blends composition, the hard phase content, time and temperature. With the decrement of the hard phase PS concentration, the loss tangent of the soft phase increases while the loss tangent of the hard phase and the storage modulus decrease. All samples have a single T_g of the hard phase and a single T_g of the soft phase. The glass transition temperatures decrease as the content of the PS phase decreases. At the constant load the creep values increase and those of creep modulus decrease over a period of time, for all examined samples. These effects are more pronounced in samples with lower content of hard phase and at higher temperatures. The time-temperature correspondence principle was applied to create master curves for the reference temperature 25°C for the creep modulus of PS-HI, SBS and PS-HI + SBS blends on a time scale far outside of the range measured by DMA experiments. These results enable us to predict the useful life of our copolymers and their blends in a wide range of time and temperature.     

Microphase separated structures based on N-substituted polydiallylamines

The ionogenic polymers namely poly(N,N-diallyl-N-cetylammonium hydronitrate) (PDACA · HNO₃) and poly(N,N-diallyl-N,N-dimethylammonium chloride)-block-poly(cetyl acrylate) (PDADMACl-block-PA-16) were synthesized via activation of the terminal double bond of the PDADMACl precursor and initiation of the polymerization of the acrylic monomer in alcohol solution. The microphase separated structure of a blend of both homopolymers and of the block copolymer was proved by differential scanning calorimetry (DSC) and X-ray diffraction measurements. Side chain crystallization in PDA-CA · HNO₃ completely restricts the crystallization of the ionogenic backbones which, however, control the layered structure and the crystallization of the aliphatic chains. In PDADMACl-block-PA-16 crystalline polyacrylate blocks coexist with crystalline ionogenic blocks. The length of the polyacrylate block influences the ability of the ionogenic block to form the crystalline structure.     

Synthesis of 3-aryl(hetaryl)-1,2,3-diazaphospholines

A reaction of cyclohexanone phenylhydrazone with (het)aryldihalogenophosphines has been studied. As shown, cyclohexanone phenylhydrazone reacts with phenyldibromophosphine and 5-methyl-2-furyldibromophosphine to provide the corresponding 1,2,3-diazaphospholines in high yields. The diazaphospholines thus obtained have been derivatized. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:81–83, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20074     

A facile preparation of some novel class II mesoionic xanthine acyclonucleosides

The synthesis of the first examples of Class II mesoionic xanthine acyclonucleosides is described. A series of mesoionic anhydro-(8-methoxyalkyl-5-hydroxy-7-oxothiazolo[3,2-a]pyrimidinium hydroxides), Class II mesoionic analogs isoconjugate with xanthine, were prepared by the thermal condensation of methoxyalkyl-2-aminothiazoles with substituted bis(2,4,6-trichlorophenyl)malonic esters. The memoxyalkyl-2-aminothiazoles were prepared via an aromatic nucleophilic substitution reaction between 2-bromothiazole and the appropriate methoxyalkylamine in excess. The resulting 8-methoxyalkyl-substituted mesoionic xanthines were demethylated using iodotrimethylsilane in acetonitrile at room temperature to afford the corresponding mesoionic anhydro-(8-hydroxyalkyl-5-hydroxy-7-oxothiazolo[3,2-a]pyrimidinium hydroxides) as the Class II mesoionic xanthine acyclonucleosides.     

Cointegration applied to purchasing-power analysis of mean Ukrainian total wages

The main purpose of this study is to propose Johansen's [6] methodology of linear cointegration analysis as a tool to measure the purchasing power of the Ukrainian mean total wages (MTW) within the period of November 1993 to December 2004 expressed in terms of prices of some basic food products or of the Consumer Price Index (CPI). Nineteen monthly price time series of basic food products, the CPI and MTW published by the State Committee of Statistics of Ukraine (Derzhkomstat) have been selected. Preliminary studies of stationarity are undertaken to establish their degree of integratedness with a battery of adequate unit root tests. A cointegration analysis of couples of one of these price time series of some basic food products, respectively the CPI and the MTW time series are realised, yielding linear functions between both selected series, establishing tentative long-run equilibrium relations for subperiods shorter than the interval 1993 to 2004. The results show that the purchasing power of the MTW, expressed in terms of the prices of some basic food products, respectively the CPI, gradually increased from 1993 to 2004. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

The conformal points of the generalized Thirring model II

In the large-N limit, conditions for the conformal invariance of the generalized Thirring model are derived, using two different approaches: the background field method and the hamiltonian method based on an operator algebra, and the agreement between them is established. A free field representation of the relevant algebra is presented, and the structure of the stress tensor in terms of free fields (and free currents) is studied in detail.     

Viscose-Derived Activated Carbons Fibers as Highly Efficient Adsorbents for Dimethoate Removal from Water

Extensive use of pesticides resulting in their accumulation in the environment presents a hazard for their non-target species, including humans. Hence, efficient remediation strategies are needed, and, in this sense, adsorption is seen as the most straightforward approach. We have studied activated carbon fibers (ACFs) derived from viscose fibers impregnated with diammonium hydrogen phosphate (DAHP). By changing the amount of DAHP in the impregnation step, the chemical composition and textural properties of ACFs are effectively tuned, affecting their performance for dimethoate removal from water. The prepared ACFs effectively reduced the toxicity of treated water samples, both deionized water solutions and spiked tap water samples, under batch conditions and in dynamic filtration experiments. Using the results of physicochemical characterization and dimethoate adsorption measurements, multiple linear regression models were made to reliably predict performance towards dimethoate removal from water. These models can be used to quickly screen among larger sets of possible adsorbents and guide the development of novel, highly efficient adsorbents for dimethoate removal from water.     

(+)-Catechin Stereoisomer and Gallate Induce Oxidative Stress in Rat Aorta

The goal of the work was to study changes in the activity of the angiotensin-converting enzyme (ACE) and production of reactive oxygen species (ROS) in the aorta of rats after the intraperitoneal injection of stereoisomers of catechin and gallate. The activity of ACE in the aorta sections was determined by measuring the hydrolysis of hippuryl-l-histidyl-l-leucine. The production of ROS in the aorta sections was estimated from the oxidation of dichlorodihydrofluorescein. The time and dose dependences of the effect of catechin stereoisomers and gallate on ACE activity and ROS production in the aorta were studied. It was shown that (+)-catechin and gallate increased the ACE activity and ROS production, and (−)-catechin and (−)-epicatechin did not influence these parameters. The doses of (+)-catechin and gallate that increased the ACE activity to a half-maximal value (AD₅₀) were 0.04 and 0.03 µg/kg, respectively. Fucoidin, a blocker of leukocyte adhesion to the endothelium, reduced the ACE activity to the control level in the aortas of (+)-catechin-treated rats.     

Reversal of Tabun Toxicity Enabled by a Triazole-Annulated Oxime Library—Reactivators of Acetylcholinesterase

Acetylcholinesterase (AChE), an enzyme that degrades the neurotransmitter acetylcholine, when covalently inhibited by organophosphorus compounds (OPs), such as nerve agents and pesticides, can be reactivated by oximes. However, tabun remains among the most dangerous nerve agents due to the low reactivation efficacy of standard pyridinium aldoxime antidotes. Therefore, finding an optimal reactivator for prophylaxis against tabun toxicity and for post-exposure treatment is a continued challenge. In this study, we analyzed the reactivation potency of 111 novel nucleophilic oximes mostly synthesized using the CuAAC triazole ligation between alkyne and azide building blocks. We identified several oximes with significantly improved in vitro reactivating potential for tabun-inhibited human AChE, and in vivo antidotal efficacies in tabun-exposed mice. Our findings offer a significantly improved platform for further development of antidotes and scavengers directed against tabun and related phosphoramidate exposures, such as the Novichok compounds.