Methodology for studying the combustion products composition from various materials

Изложены методология и принципы лабораторного исследования состава продуктов горения различных материалов с использованием таких инструментов, как газовая и газожидкостная хроматография, масс-эффузио-спетрометрия. Большое внимание уделено применяемым в хроматографических колонках сорбентам и их температурным режимам, а также способам приготовления образцов для исследований. Рассмотрены вопросы детектирования различных компонентов в смеси продуктов горения. Результаты исследований продуктов горения разных материалов представлены в табличной форме, при этом в скобках указаны рассчитанные индексы токсичности С, оцененные по литературным данным (смертельная для человека концентрация при получасовой экспозиции). The article discusses the issues of determining the qualitative and quantitative composition of the combustion products from synthetic and natural materials. Multicomponent mixtures of volatile combustion products contain compounds of inorganic and organic origin. To determine the composition of the combustion products from various materials there is proposed the methodology and principles of laboratory research using such instruments as gas and gas-liquid chromatography, mass spectrometry, infrared and ultraviolet spectroscopy, and visible-field spectroscopy. These methods make it possible to identify certain chemicals. For example, organic compounds are analyzed by chromatography. Inorganic substances are determined by converting them into colored compounds and by analyzing their spectrum in the visible and ultraviolet regions. When developing methods of chromatographic and spectrophotometric studies, it is proposed first of all to identify the qualitative composition of combustion products based on information about the composition of polymer molecules of the studied natural or synthetic materials. Such an assessment, as an example, was made by studying the combustion products of polyethylene. The molecular weights were determined using the MX-1312 chromatomassefusiometer. To determine the molecular weight of a substance, a mathematic formula was obtained based on mathematical processing of experimental data. A special method has been developed to reduce the processing time of effusiograms (by 10-15 times). Much attention is paid to the sorbents used in chromatographic columns, their temperature conditions, and methods of preparing samples for research. Methods of identification of various components in a mixture of combustion products using various detectors are considered. The results of studies of the combustion products from different materials are presented in tabular form, with the calculated toxicity indices, С, estimated according to the literature data (lethal concentration for humans at half-hour exposure) are indicated in parentheses.

Physico-chemical analysis, systematic benchmarking, and toxicological aspects of the JWH aminoalkylindole class-derived synthetic JWH cannabinoids

We are presenting the results obtained by computing different toxicity indices for some of the newest JWH synthetic cannabinoids, by using (Q)SAR models, ADME(T) predictions, simulations of NMR spectral techniques and other different computational dedicated software packages and forensic analytical tools. We have examined the main physical and chemical properties and evaluated the behavioral neurotoxicity and pharmacokinetic profile of 16 aminoalkylindole class-derived synthetic cannabinoids JWH as compared to the Delta-9-tetrahydrocannabinol (Δ9-THC), which was chosen as a standard compound. For this purpose, the geometries of the molecules have been optimized by using the AM1 semi-empirical quantum method. The conclusions of a comparative analysis of the toxicities of synthetic and natural cannabinoids are presented.

High Performance Computing and Machine Learning in support of Toxicokinetic-Toxicodynamic Modelling for the understanding of Mixture Effects

Toxicokinetics-Toxicodynamics (TKTD) models are increasingly used for inference of toxicity indices of interest in Environmental Risk Assessment (ERA) thanks to their clear description of numerous mechanisms, from the kinetics of compounds inside organisms (Toxicokinetics, TK) to their related damages and effect dynamics at the individual level (Toxicodynamics, TD) [1]. TKTD models offer the advantage of accounting for temporal aspects of both exposure and toxicity, considering data points all along the time course of experiments. In addition, TKTD models allow predictions under untested situations from time-variable exposure profiles either measured in the field or simulated in risk assessment scenarios. Although ERA can follow a compound-by-compound approach, in practice, ecosystems are exposed to many chemical products, from agricultural, industrial and domestic sources. Using TKTD models to describe such mixture effects over time requires making assumptions a priori on potential interactions of involved products [2]. These assumptions are then tested and evaluated based on fitting TKTD models to observed data under exposure to mixtures. This poster illustrates how high performance computing [3] and machine learning [4] may be of particular help for the inference of TKTD models without a priori knowledge on emerging chemical interactions that leads to cocktail effects.

morse: an R-package in support of Environmental Risk Assessment

Package morse is devoted to the analysis of experimental data collected from standard toxicity tests. It provides ready-to-use functions to visualize a data set and to estimate several toxicity indices to be further used in support of environmental risk assessment in full compliance with regulatory requirements. Such toxicity indices are indeed classical requested by standardized regulatory guidelines on which national agencies base their evaluation of applications for marketing authorisation of chemical active substances. Package morse can be used to get estimates of LCx (x% Lethal Concentration) or ECx (x% Effective Concentration) by fitting standard exposure-response models on toxicity test data. Risk indicator estimates as well as model parameters are provided along with the quantification of their uncertainty. Package morse can also be used to get estimates of the NEC (No Effect Concentration) by fitting a Toxicokinetic-Toxicodynamic (TKTD) model (namely GUTS models, that is General Unified Threshold models of Survival). Using GUTS models also allow to get estimates of LC(x,t) (whatever x and t) and LP(x,t), this later being defined by EFSA as the x% multiplication factor leading to an additional reduction of x% in survival at the end of the exposure profile. Above all, GUTS models can be used on data collected under time-variable exposure profiles. This paper illustrates a typical use of morse with survival data collected over time and at different increasing exposure concentrations, analysed with the reduced version of GUTS models based on the stochastic death hypothesis (namely, the GUTS-RED-SD model). This example can be followed step-by-step to analyse any new data set, as long as the data set format is respected.

Diatom Algae-Indicators of Water Quality in the Lower Zarafshan River, Uzbekistan

This work is the first, the purpose of which was a comprehensive assessment of the ecological state of the lower reaches of the Zarafshan River using bioindication of water quality by diatoms based on species’ ecological preferences, pollution indices, statistics, and ecological mapping. A total of 198 species and subspecies of diatoms were first identified from 195 samples collected four times a year at six sites in the lower reaches of the Zarafshan River in 2009–2015. The richest species were Cymbella, Navicula, and Nitzschia. Pleurosira laevis, resistant to salinity, was first found in aquatic habitats in Uzbekistan. Bioindicators of nine environmental variables make up 91% of the list. Distribution analysis of variables, pollution indices (SLA—SládečDek index of saprobity), and toxicity indices (WESI—Water Ecosystem State Index) show increases in salinity, turbidity, and decreases in organic pollution downstream. The source of acidification can be the Navoi region. We found an increase in the ability to self-purify with an increase in species richness and abundance of diatoms in the lower part of Zarafshan. Thus, the ecosystem of the studied part of the river successfully copes with the incoming pollution from the middle part of Zarafshan and demonstrates some stability and successful self-purification with a water quality class of 2–3. The first studied lower reaches of the ecosystem of the Zarafshan River using bioindicators, statistics, and ecological mapping show that the problem of aridization in Central Asia does not necessarily lead to degradation of the river ecosystem and an increase in pollution, but with rational water use can improve water quality and self-purification processes. Hence, diatoms can be good indicators of river water quality in a semi-arid region and reflect the climate and anthropogenic load change. We recommend that attention be paid to nutrient and turbidity management and to expand state monitoring points to the lower part of the river up to the Karakul region.

The (-)-epigallocatechin gallate (EGCG) ameliorates hyperglycemia and hyperlipidemia - mediated oxidative stress in liver and kidney of alloxan induced diabetic mice

Background: Diabetes mellitus has become a serious problem associated with health complications, such as metabolism disorders and liver-kidney dysfunctions. The inadequacies associated with conventional medicines have led to a determined search for alternative natural therapeutic agents. The present study is conducted to evaluate the hypoglycemic, antilipidemic and antioxidant effects of EGCG in surviving diabetic mice.Methods: Alloxan diabetic mice were injected with EGCG. Their bloods were collected and submitted to various biochemical measurements, including blood glucose, cholesterol, triglycerides, urea, creatinine and transaminases. Their livers and kidneys were isolated to perform histological analysis.Results: Both EGCG and insulin treatments of diabetic mice resulted in a significant reduction in fasting blood glucose level. EGCG supplementation also ameliorated hepatic as well as renal toxicity indices. Moreover, diabetic mice injected by EGCG exhibited significant changes in antioxidant enzyme activities in the liver and kidney. Histological analyses also showed that it exerted an ameliorative action on these organs and efficiently protected the liver-kidney functions of diabetic mice.Conclusion: The findings revealed that EGCG administration induced attractive curative effects on diabetic mice, particularly in terms of liver-kidney functions. EGCG can, therefore, be considered as a potential strong candidate for future application to treat and prevent diabetes.

STUDYING COMBINED SUBCHRONIC TOXICITY OF LEAD AND CADMIUM WITH A SPECIAL FOCUS IN TERMS OF THEIR CARDIOVASCULAR EFFECTS

Introduction. Exposure to lead and cadmium is an important risk factor for the health of workers in copper smelters and refiners. Numerous epidemiological studies have revealed a relationship between exposure to lead and cadmium and the development of hypertension and cardiovascular disease. Material and methods. At the closing stage of the experiment, we registered over 50 characteristics of animals’ health status, including functional, cytological, morphological (with morphometry of certain organs) and biochemical indices. The exposure period accounted for 6 weeks, during which we monitored the general health status of the exposed animals and the control group. Experimental estimates of some of the health indices were used for mathematical modeling of the combined Pb+Cd exposure via Response Surface Methodology. Results. The obtained results were consistent with our earlier conclusions that there are different types of combined Pb+Cd toxicity. The ultimate interaction of toxic agents is determined by what effect is being considered, the level of the effect, and the ratio of the doses. The same toxic mixture can produce a range of interactions, from synergism to antagonism. In this study, we discovered cardiovascular toxicity indices (ECG, BP) to do also suggest that there are different types of combined Pb+Cd toxicity. Most ECG features suggest a synergistic relationship between Pb and Cd, except for P-wave, which amplitude may be interpreted as an indication of Pb-Cd antagonism. Moreover, the antagonistic relationship between Pb and Cd was established with respect to their effects on blood pressure in rats. Conclusion. It is shown that there are different types of lead and cadmium combined cardiovascular toxicity in ionic form in rats.

Summation of disinfection by-product CHO cell relative toxicity indices: sampling bias, uncertainty, and a path forward

Predicted toxicity has been used to determine if a treatment process is either beneficial or detrimental to the overall DBP toxicological profile of water samples. Selection of the DBPs to measure is important and may result in biased conclusions.