We describe a spectrometer consisting of a vector network analyzer, a gas absorption cell, and a quasi-optical bench that acquires terahertz spectra of gaseous substances and mixtures. We tested volatile organic compounds that are medical biomarkers or chemicals which can be found on the US Environment Protection Agency list of harmful substances. Absorption spectra at gas pressures between 10 ...

Despite frequent investigations the problem of the mechanism of uricolysis still remains unsolved. The attempts to identify those substances, whose formation by oxidative agents from uric acid or the purines is easily accomplished by the organic chemist, as products of the. intermediary metabolism of uric acid have failed; nor has the study of these same substances in metabolism thrown addition...

The publications on Kjeldahl’s method for determining nitrogen that have appeared since Kjeldahl’s (1) original paper in 1883 perhaps outnumber those on any other analytical method in the same period of time.1 The diversity of papers is attributable to the immense usefulness of the method, to its need for modifications for applications to various types of organic and inorganic compounds, and to...

The breeding habitat of sandflies is a little studied and poorly understood phenomenon. More importantly, oviposition behaviour is a largely neglected aspect of sandfly biology and this knowledge gap further undermines our understanding of the biology of sandflies. Pheromones released by the eggs play an important role in identifying good sites for oviposition by female insects. Several recent ...

The total stratospheric organic chlorine and bromine burden was derived from balloon-borne measurements in the tropics (Teresina, Brazil, 5 • 04 ′ S, 42 • 52 ′ W) in 2005. Whole air samples were collected cryogenically at altitudes between 15 and 34 km. For the first time, we report measurements of a set of 28 chlorinated and brominated sub-5 stances in the tropical upper troposphere and strato...

The recent complete ban on the use of the antibiotic growth promoting substances by the EU and partly in several other countries worldwide urged nutritionists and animal scientists to seek for alternatives. The use of organic acids in poultry and pig nutrition appears to be an interesting solution that can enhance the eff ect of other feed additives, as well. In combination with other substance...

This paper aims to characterize the evolution of organic matter during the composting of municipal solid waste (MSW). During the 46-day composting process, six samples with different composting time were collected from Songjiang Solid Waste Biological Treatment Plant in Shanghai, China. Dissolved organic matter (DOM) was extracted by ultra-pure water, and the UV-Visible (UV-Vis) spectra of DOM ...

The Residue on Ignition Test specified in General Tests, Japanese Pharmacopeia is a method to measure the weight of the residual substance not volatilized when the sample is ignited under a constant condition. Generally, this test is intended to determine the content of inorganic substances contained as impurities in an organic substance, and, occasionally, to determine the amount of inorganic ...

Objective Maternal exposure to various contaminants has been reported to be correlated with congetinal heart defects (CHDs). In this study, the effect of maternal exposure to organic and inorganic environmental factors upon the incidence of CHDs was investigated. We conducted a retrospective birth cohort study of infants born in the Maternal and Child Health Hospital of Panyu District in Guangz...