INTRODUCTION Incomplete cross-linking of composite dental materials leads to their susceptibility to degradation in the environment of non-organic and organic solvents, contributing to the release of chemical compounds which are potentially harmful to living organisms. OBJECTIVE The aim of the study was an evaluation in in vitro conditions of releasing of potentially toxic substances from six...

"Organic chemical nomenclature is an infuriating subject." So wrote Cahn in 1959. One of the fundamental differences between organic and inorganic chemistry is that carbon atoms have the property of Unking on to one another to form chains or rings. The ordinary inorganic molecular formula rarely contains more than ten atoms, but the organic molecule may number its component atoms in dozens, in ...

The research work covers polymer membrane preparation, morphology study, and structural characterization of the membrane and study of the taste sensing characteristics of membrane for five different taste substances. FTIR spectroscopic analysis, UV spectroscopic analysis and SEM were carried for the structure and morphology of polyacrylamide (PAM) grafted cellulose membrane. Sensor characterist...

The presence of calcium and humic substances or natural organic matter (NOM) in surface waters can cause severe fouling of nanofiltration (NF) membranes. Conditions of fouling were studied using a stainless steel stirred cell of volume 185 mL and a membrane area of 21.2*10-4m2 at a transmembrane pressure of 5 bar. Deposition of organic matter was determined by mass balance in feed and concentra...

Three types of commonly used commercial treatment processes were investigated for the removal of volatile organic compounds (VOCs) from hazardous waste: thin-film evaporation, steam stripping, and distillation. These Unit operations were evaluated for their potential to control emissions from hazardous waste treatment, storage and disposal facilities (TSDFs) by reducing waste VOC content. One-d...

1. Introduction 1. Introduction Transport and availability of organic pollutants in soils, sediments and aquifers are closely related to the interactions of these compounds with the natural organic polymers (so-called soil organic matter [SOM], e.g. humic substances) present in these media. Contaminants may be either immobilized and retarded (and sometimes conserved for decades [1]) or transpor...

A method for estimating inhibition of pollen tube growth was developed. Pollen is placed in straight lines on an agar surface where it responds uniformly and predictably to aqueous solutions of germination-inhibiting substances located in wells at the ends of the lines. A scale of ratings, roughly corresponding to serial, doubled concentrations of inhibiting substances, was devised. Water-solub...

The submitted paper deals with the problems of trapping and enriching the gases and aerosols of the substances to be determined in the ambient atmosphere. Further, the paper is focused on the working principle of the miniaturized portable continuous concentrator we have designed and the possibilities of its application in air sampling and accumulation of organic and inorganic substances with wh...

Humic acids are complex, partly macromolecular, yellow-brownish substances occurring in soils, waters and sediments. In order to bring some light on their molecular structure, crop humic acids were cleaved by alkaline hydrolysis (KOH). The products were fractionated by thin layer chromatography to give mono-alcohols which were analysed as acetate derivatives by gas chromatography coupled to mas...

An understanding of the chemistry and reactions of humic acids and related substances is crucial to an understanding of the nature and properties of soils. A comprehensible structural representation of humic substances is presented and the simplified model is used to illustrate: (i) the way in which stable humus is formed from lignin; (ii) forms of organic N in soils; (iii) the interaction of h...