Toxicity of environmentally important micropollutants on three trophic levels

Micropollution is a serious environmental problem caused by continuous entry of trace quantities of toxic chemical substances into the aquatic environment. In the present study, three trophic levels of the aquatic ecosystems were used to evaluate the acute toxicities of environmentally important micropollutants including heavy metals, pesticides and drugs. There is a scarcity of information on toxicity of the studied substances on marine water algae. Among studied micropollutants, the most toxic chemical to Daphnia magna and Danio rerio was found to be 1-Chloro-2,4 dinitrobenzene with EC50 of 0.002 and 4.2 mg/L, respectively. Although this compound was also toxic to marine algae, Phaeodactylum tricornutum, arsenic showed the highest toxicity to the algae with EC50 of 2.4 mg/L. As compared to other organisms, D. magna was found to have higher sensitivity to all of the tested micropollutants.

The use and control of antimicrobial substances in animal feed – EU regulations and the risks related to their presence

Animal feeds are routinely subject to contamination from diverse sources, including environmental pollution, activities of microbes, and veterinary drug residues. Contamination of feed with chemical substances such as coccidiostats or antibiotics can occur at the stage of production, transport and storage, and their presence may have a negative impact on the health of animals consuming feed contaminated with certain chemicals. This study presents the legal requirements for the production of feed, the presence of antimicrobial substances in feed, and the problem of contamination of feed with antibacterial substances as well as the possible transfer of these compounds to the animal tissues and the natural environment.

Research on New Cleaning Method of Automobile Air Conditioner

on the car air conditioning cleaning market at present there are some problem of cleaning method has been widely criticized, simple and convenient cleaning method, in particular, the so-called clean air conditioning is “only spray cleaner, no water washing”, this will cause the pipeline internal dirt clean is not complete, easy to internal damage other parts of automobile air conditioning, affect the normal operation of the air conditioning, the remaining part of the chemical substances will also produce secondary pollution to the air inside the car, seriously affects people’s health and safety.

Promising chemical barrier substance applied to ichthyofauna in hydroelectric plants

In hydroelectric plants, there are, on a regular or untimely basis, shutdowns of the generating units in order to carry out some maneuvers for tests and mechanical maintenance. The low operating flow increases the probability of accumulation of ichthyofauna in the draft tube. As a result, the variables that determine the quality of water can change, which requires a broad and coordinated human effort to rescue trapped fish. In addition to the risks related to work safety, there are large economic liabilities as a result of the downtime of the generating units. To minimize this problem, it is necessary to improve techniques for repelling fish from risk areas. The detection of chemical substances in water is one of the most efficient methods of communication between fish. Thus, this study presents a brief review of alarm substances, which are released by the fish epidermis as a sign of defensive response to a dangerous situation and are promising for use as a chemical barrier in the hydroelectric sector.

In Vitro Anti-SARS-CoV-2 Activity of Selected Metal Compounds and Potential Molecular Basis for Their Actions Based on Computational Study

Metal-based drugs represent a rich source of chemical substances of potential interest for the treatment of COVID-19. To this end, we have developed a small but representative panel of nine metal compounds, including both synthesized and commercially available complexes, suitable for medical application and tested them in vitro against the SARS-CoV-2 virus. The screening revealed that three compounds from the panel, i.e., the organogold(III) compound Aubipyc, the ruthenium(III) complex KP1019, and antimony trichloride (SbCl3), are endowed with notable antiviral properties and an acceptable cytotoxicity profile. These initial findings prompted us to perform a computational study to unveil the likely molecular basis of their antiviral actions. Calculations evidenced that the metalation of nucleophile sites in SARS-CoV-2 proteins or nucleobase strands, induced by Aubipyc, SbCl3, and KP1019, is likely to occur. Remarkably, we found that only the deprotonated forms of Cys and Sec residues can react favorably with these metallodrugs. The mechanistic implications of these findings are discussed.

Experimental investigation of simultaneous effect of parabolic trough collector and flat external reflectors on performance of stepped solar still

In this research, the performance of stepped solar still has been experimentally evaluated. For this purpose, a parabolic trough collector has been used to preheat the saline water entering the solar still. Also, two flat external reflectors have been employed to increase the amount of solar energy received by the steps and the collector of the system. The findings of this research indicate that the use of two flat external reflectors is more effective than using the trough collector. Also, it is more efficient to apply both mechanisms simultaneously than to use them separately. According to the obtained results, the distilled water output of the solar still is 760, 1,560, 2,440 and 2,760 ml/m2, respectively, for operating the conventional solar still, using the trough collector, using the two flat external reflectors, and using the collector and reflectors simultaneously. The electrical conductivity due to the presence of salt and chemical substances dissolved in the distilled water discharged from the still is 255, 215, 62 and 38 micro Siemens per centimetre, respectively, for each of the four mentioned cases. These experiments show that by applying the proposed mechanisms, the amount of distilled water can be increased, and its purity can be enhanced.

Estimation of Shutdown Schedule to Remove Fouling Layers of Heat Exchangers Using Risk-Based Inspection (RBI)

Oil and Gas plants consist of a set of heat exchangers, which are used in recovering the waste heat from product streams to preheat the oil. The heat transfer coefficient of exchangers declines considerably during the operation period due to fouling. Fouling in heat exchangers is a complex phenomenon due to the acceleration of many layers of chemical substances across tubes of heat exchangers resulting from chemical reactions and surface roughness. In this paper, the fouling process was determined as a critical failure in the heat exchanger. Failure is an accelerated fouling layer across the heat exchanger tubes, which can be the reason for the clogging of tubes. Hence, a risk assessment was conducted using the Risk-Based Inspection (RBI) approach to estimate the probability of fouling in heat exchangers. The results showed that the RBI approach can be used successfully to predict the suitable time to shut down the plant and conduct the fouling cleaning process.