Calculation of fundamental thermochemical parameters of phosphoranes by the additivity scheme

Using the additivity scheme, experimental enthalpies of vaporization and formation of phosphoranes were analyzed, group contributions to the enthalpies of vaporization and formation were determined, and thermochemical parameters of five-coordinate phosphorus derivatives were calculated. © 2005 Pleiades Publishing, Inc

Electronic effects on the enthalpy of specific interaction of three-coordinate phosphorus compounds and acetals with chloroform

The effect of electronic factors in five- and six-membered cyclic three-coordinate phosphorus compounds and acetals on the enthalpy of their specific interaction with chloroform was estimated. © 2008 MAIK Nauka

Study of intra- and intermolecular interactions with participation of α-phosphorylated amines and alcohols in different solvents

Specific interactions of α-hydroxy- and α-aminophosphonates in chloroform and pyridine solutions were studied by theoretical (molecular mechanics) and experimental methods (calorimetry and IR spectroscopy). A competition between intra- and intermolecular interactions and effect of steric factor in molecules of organophosphorus compounds were revealed

Polynomial dependence for the calculation of vaporization enthalpies of organophosphorus compounds

Enthalpies of vaporization of organic phosphorus compounds are related to the normal-pressure boiling points through a polynomial dependence. Each class of organophosphorus compounds is characterized by its own specific parameters of the general dependence. The polynomial dependences may be used for the calculation of vaporization enthalpies of organophosphorus compounds with different modes of phosphorus coordination. © 2005 Pleiades Publishing, Inc

Enthalpies of specific interaction of heteroatom derivatives of three-coordinate phosphorus with chloroform

The nature of hydrogen bonds formed by chloroform with three-coordinate phosphorus derivatives containing sulfur, silicon, and chlorine atoms and their carbon analogs was revealed by analysis of the experimental enthalpies of specific interactions. The main donor centers in the examined compounds were found to be oxygen atoms and π-electron systems of aromatic rings. Sulfur atoms give rise to weaker complexes as compared to oxygen. Phosphorus, chlorine, and silicon atoms are not involved directly in specific interactions with the solvent. © 2008 MAIK Nauka

Assessment of biodamage resistance of various concrete grades

© 2016, International Journal of Pharmacy and Technology. All rights reserved.At estimation of modern mineral construction materials resistance to Aspergillus niger; Aureobasidium pullulans; Trichoderma sp. it was shown that 28-day exposure of test samples with micromycetes according to GOST 310.4-81 does not reduce their chemical stability coefficient. Analysis of growth rate of selected micromycetes in solid Czapeck-Daux medium allows to relate them to r-strategists. At cultivation of microscopic fungi in liquid Czapeck-Daux medium one-, two-and tribasic (acetic, oxalic, apple and citric) organic acids were identified. High rate of micromycetes growth and formation of wide range of organic acids during their growth gives the basis for supposition that at long-lasting contact of microscopic fungi with construction materials the damage of the latter cannot be excluded

Thermochemistry of heteroatomic compounds X. The thermochemistry of solution and solvation of substituted alkylphosphonic derivatives

The enthalpies of vaporization of different classes of phosphorylated alcohols and amines were determined from their enthalpies of solution in hexane and carbon tetrachloride. The enthalpies of specific (hydrogen-bond) interaction with the solvents (chloroform and pyridine) of derivatives containing X-H groups (X=O or N) in the α-position to the P=O group were detemined. The results were explained in terms of the spatial structure of such compounds

Slow drowning of Tibetan grasslands fenced in by Beijing

The initiative that led to pasture being fenced off is part of a string of Chinese grassland policies. Although Tibet has its own regional government, policies concerning what is called the Tibet Autonomous Region are effectively handed down from the Chinese government in Beijing. This article traces the degradation of grasslands and with it, nomadic culture, due to fencing the land. It is becoming clear that grassland privatization, which was introduced to protect the environment, is causing biodiversity loss and a decline in grassland quality. Due to climate change, meltwater submerges the highlands and snowstorms hit trapped herds; shrinking glaciers defrost soil, increasing flow into mountain lakes

Enthalpies of specific interaction of heteroatom derivatives of three-coordinate phosphorus with chloroform

The nature of hydrogen bonds formed by chloroform with three-coordinate phosphorus derivatives containing sulfur, silicon, and chlorine atoms and their carbon analogs was revealed by analysis of the experimental enthalpies of specific interactions. The main donor centers in the examined compounds were found to be oxygen atoms and π-electron systems of aromatic rings. Sulfur atoms give rise to weaker complexes as compared to oxygen. Phosphorus, chlorine, and silicon atoms are not involved directly in specific interactions with the solvent. © 2008 MAIK Nauka

Calculation of fundamental thermochemical parameters of phosphoranes by the additivity scheme

Using the additivity scheme, experimental enthalpies of vaporization and formation of phosphoranes were analyzed, group contributions to the enthalpies of vaporization and formation were determined, and thermochemical parameters of five-coordinate phosphorus derivatives were calculated. © 2005 Pleiades Publishing, Inc