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Volatile organic compounds (VOCs) such as benzene, toluene, and xylene are toxic air pollutants which are released into the atmosphere by various human activities such as gasoline production and use, chemical manufacturing and incineration of certain waste. These pollutants are also harmful to the environment, causing harm to plants, aquatic life, and soil quality. Therefore, it is important to implement measures to reduce emissions from these substances. The purpose of this paper is to evaluate the air pollutants caused by benzene, toluene, and xylene at Kazakhstan Petrochemical Industries Inc. LLP in 2021–2022. In order to calculate the sample size for this crosssectional study, the preliminary evaluation findings from a related study that measured the concentration of hydrocarbons in petrochemical facilities were employed. 281 samples were gathered between the winter and summer of 2022. The national institute for occupational safety and health (NIOSH) methods of 1501 was applied to conduct the sampling and analysis of pollutants. The air was sampled using a charcoal tube sampler that was attached to a pump. The chemicals were then extracted using the solvent carbon disulfide (CS2 ), and samples were then analyzed using a capillary-equipped gas chromatography-mass spectrometer. The collected data were analyzed by SPSS software version 23.0. The findings demonstrated that benzene concentrations in the sampling areas throughout the winter and summer were higher than the recommended value advised by the American conference of governmental industrial hygienists (ACGIH). [ABSTRACT FROM AUTHOR]

The density functional B3LYP was exploited in order to scrutinize the impact of antisite defects on the sensing capability of an AlP nanotube (AlP-NT) in detecting the gas O3. Due to the low adsorption energy (Ead = − 7.4 kcal/mol), O3 had a weak interaction with the pure and the P-antisite AlP-NT (DP). Therefore, it is not possible to use the pure AlP-NT and DP as sensors. However, there was a substantial increase in tube reactivity and sensitivity when O3 approached the Al-antisite defected AlP-NT (DAl). Its adsorption released an energy of − 24.3 kcal/mol. There is a reduction in the energy gap of the HOMO–LUMO of DAl from 2.25 to 1.41 eV (~ − 37.3%) when O3 is adsorbed. Therefore, we found that DAl as adsorbate increases its sensitivity much more than the DP and pure AlP-NT examined in this work. The computed recovery time for the DAl was 50.9 s, which is short. The theoretical results of the current study can provide further insights into the practical applications of AlP nanostructures. [ABSTRACT FROM AUTHOR]

Thermoelastic damping (TED) has been discerned as a definite source of intrinsic energy loss in miniaturized mechanical elements. The size-dependent structural and thermal behavior of these small-sized structures has been proven through experimental observations. As a first attempt, this article exploits nonlocal strain gradient theory (NSGT) and nonlocal dual-phase-lag (NDPL) heat conduction model simultaneously to acquire a mathematical formulation and analytical solution for TED in nanobeams that can accommodate size effect into both structural and heat transfer fields. For this purpose, the coupled equations of motion and heat conduction are firstly extracted via NSGT and NDPL model. Next, by deriving the distribution of temperature from heat conduction equation and substituting it in the motion equation, the unconventional thermoelastic frequency equation is established. By deriving the real and imaginary parts of the frequency from this equation and employing the definition of quality factor, an explicit solution is given for approximating TED value. The veracity of the proposed model is checked by comparing it with the solutions reported in the literature for specific and simpler cases. A diverse set of numerical results is then presented to appraise the influence of some factors like structural and thermal nonlocal parameters, strain gradient length scale parameter, geometrical parameters, mode number and material on the amount of TED. According to the results, use of NDPL model yields a smaller value for TED than DPL model, but prediction of NSGT about the magnitude of TED, in addition to the relative amounts of its two scale parameters, strongly depend on other factors such as aspect ratio, vibration mode and material type. [ABSTRACT FROM AUTHOR]

A theoretical research study was conducted into the possibility of using a two-dimensional graphene-like material silicon carbide nano-sheet (2D-SiCNS) as an anode in rechargeable Ca-ion batteries by performing DFT computations. For this purpose, the electrochemical properties during the charging process, the diffusion of Ca ion, the electronic structures, and the changes in the geometrical structures were investigated. The adsorption energy (Ead) of Ca on top of the Si atom was more than Ead of other sites. The maximum theoretical capacity of the 2D-SiCNS reached 507 mAh/g, which was accompanied by a slight change in the spacing of the Si–C band. Also, open circuit voltage (OCV) changes with changes in the concentration of adsorbed Ca atoms on the 2D-SiCNS surface were investigated. Moreover, the appropriate OCV range of Ca atoms adsorbed on the 2D-SiCNS demonstrated that this nano-sheet was suitable as a anodic material. In addition, considerable charges were transferred from Ca to the 2D-SiCNS, making it electrically conductive as a suitable anode material. [ABSTRACT FROM AUTHOR]