In recent years, the environmental necessity to replace HFC refrigerants with natural refrigerants like carbon dioxide (CO2) in refrigeration and air-conditioning applications has led to the development of an Ultra High Pressure Tribometer (UHPT) specifically customized for testing in CO2 environment at pressures comparable to those found in compressors up to 13.8 MPa (2000 psi). It was found t...

A performance analysis on a vapour compression refrigeration system with various eco-friendly refrigerants of HFC152a, HFC32, HC290, HC1270, HC600a and RE170 were done and their results were compared with R134a as possible alternative replacement. The results showed that the alternative refrigerants investigated in the analysis RE170, R152a and R600a have a slightly higher performance coefficie...

Halogenated oligosilanes and oligogermanes are interesting compounds in oligosilane chemistry from the viewpoint of silicon-based-materials. Herein, it was demonstrated that a 1,2-digermacyclobutadiene derivative could work as a bis-germylene building block towards double Si–Cl activation to give a halogenated oligometallane, a bis(chlorogermyl)dichlorosilane derivative.

A series of 5,7-dihydroxyflavanone derivatives were efficiently synthesized. Their antimicrobial efficacy on Gram-negative, Gram-positive bacteria and yeast were evaluated. Among these compounds, most of the halogenated derivatives exhibited the best antimicrobial activity against Gram-positive bacteria, the yeast Saccharomyces cerevisiae, and the Gram-negative bacterium Vibrio cholerae. The cy...

this study represents effect of four variables in performance of a heat-pump in two cities of tehran and rasht. a computer program has been developed, simulating a certain heat pump acting in different environments with different refrigerants in heating season. the analysis is based on a homogeneous model. effect of different refrigerants, depth of the buried heat exchangers and moisture conten...

A very simple and quick analytical method, based on direct aqueous injection, for determination of halogenated solvents in refinery water and wastewater, is described. There is a need to determine halogenated solvents in refinery water streams, because they may originate from several processes. There is also a need to develop methods enabling VOX to be determined in samples containing oil fract...

Aplysina is the best representative genus of the family Aplysinidae. Halogenated substances are its main class of metabolites. These substances contribute greatly to the chemotaxonomy and characterization of the sponges belonging to this genus. Due to their pharmacological activities, these alkaloids are of special interest. The chemistry of halogenated substances and of the alkaloids has long ...