1. The pepsin hydrolytic products of the pure proteins, crystalline egg albumin, crystalline edestin, and purified fibrin, are utilized by fibroblasts for their proliferation. It appears, therefore, that the growth of fibroblasts in fibrin digests and in the proteose of Witte's peptone is due to the split products of the protein itself and not to accompanying cellular constituents or other impu...

since particulate matter (total suspended particles and particulate matter with median aerodynamic diameter less than 10 µm) is one of the important pollutants in the ambient air of tehran, the capital of iran, organic substances, inorganic substances and lead levels in tsp and pm10, correlation between tsp and pm10 concentrations, ratio among the two fractions and relation between tsp and pm10...

Most chemists and many other scientists must routinely separate mixtures and identify their components. The ability to qualitatively identify the substances found in a sample can be critical. For example, an environmental chemist investigating samples of polluted ground water will want to know which toxic ions might be present in a sample. Chromatography is one of the first tools employed in su...

The biodegradation of organic substances is a natural yet poorly understood process. Given that biodegradation assessments form an integral part of chemical regulations to assess the persistent of substances this lack of knowledge needs to be addressed. Official references define the biodegradation process as "The biologically mediated degradation or transformation of chemicals usually carried ...

The direct determination in drinking water of perylene, chrysene, pyrene, benzo[a]pyrene, and benzo[k]fluoranthene, by front-face synchronous fluorimetry on a commercial SPE disk, has been evaluated. Sorbent treatment, influence of humic substances, and pH effect are discussed. In pure water the detection limits were estimated to be in the range 0.03-0.01 microg L(-1). A working pH in the range...

Most chemists and many other scientists must routinely separate mixtures and identify their components. The ability to qualitatively identify the substances found in a sample can be critical. For example, an environmental chemist investigating samples of polluted ground water will want to know which toxic ions might be present in a sample. Chromatography is one of the first tools employed in su...

On behalf of the International Union of Pure and Applied Chemistry (IUPAC), and in particular its Commission on Atomic Weights and Isotopic Abundances, I should like to inform the readers of the Journal of Research of the National Institute of Standards and Technology of the following, based on Refs. [1] and [2]. To eliminate possible confusion in the reporting of isotopic abundances on noncorr...