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The hydrometallurgical route of zinc hydroxide and synthesis of nanocrystalline ZnO is a particularly attractive method to recover oxidized lead and zinc from lead-zinc flotation tailings. In Turkey, lead-zinc complex/mixed ores along with high iron content are not suitable for conventional mineral processing methods and need hydrometallurgical treatments. Therefore, the control of iron during zinc processes is really important. In this study, hydrometallurgical process route for zinc recovery from Pb-Zn flotation tailings was investigated by considering the effects of H2SO4 concentration, leaching and roasting temperatures on the zinc dissolution considering the Eh-pH variations. The iron and zinc products were also individually examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) images in order to compare before and after leaching, precipitation and roasting steps. 83.1% Zn and 91.6% Cd leaching efficiencies were obtained from Pb-Zn flotation tailing particles with the size range of 50-110 nm from AFM image cross-sections, while lead and iron were not dissolved. Elemental sulfur started to form and produce a layer around the particles or a partially agglomerated particle in the size of 170 nm during the sulphuric acid leaching. However, majority of the particles was determined to be less than 20 microns, and AFM images showed that the size reduction between the leached and unleached particles was over 50%. Selective precipitations of iron and zinc in the form of hydroxide were performed in high recovery efficiencies of 90.1% and 99%, respectively. After the heat treatment, nanocrystalline zincite clusters of 96.6% purity were produced in the ZnO mineral form and nearly 13 nm in size. Zinc can be successfully recovered and a flotation tailings ore can be a good candidate for the production of high technology needs of nanocrystalline ZnO nanoparticles.

The polarizability of polycyclic aromatic hydrocarbons (PAHs) is an important property that relates to their abundance in natural environments. To assess the differences in the mean polarizability of planar and non-planar polycyclic aromatic hydrocarbons (PAHs), we computationally studied the PAH series of circulenes (kekulene C48H24, [13]circulene C52H26, and septulene C56H28), a number of the nearest helicenes, and their “expanded” isomers. We mean under “nearest” a close number of aromatic rings: 11 (C46H26), 12 (C50H28), 13 (C54H30), and 14 (C58H32). For these PAHs, we performed the quantum chemical calculations of thermodynamic and polarizability parameters with the PBE/3ζ density functional theory method, which is widely used in the theoretical chemistry of fullerenes and PAHs. The calculated mean polarizabilities (in Å3) ranged from 80.1 for [11]helicene to 135.5 for septulene, and while the circulenes and expanded helicenes had similar values, the mean polarizability of the normal helicenes was markedly lower. In all four pairs of helical PAHs, the expanded helicene was energetically considerably more favorable than its standard helicene isomer. Herewith, the ratio of their polarizabilities was equal to 1.3.

The specific branches of industry utilize needle coke, a carbon form with a highly anisotropic structure. Searching for novel raw materials for its production is now rigorously studied. In the present work, we use low-sulfur gasoil for this purpose, namely its high-boiling fractions. We study their chemical and physicochemical parameters with the set of physicochemical and spectral methods. The data of FT-IR and UV-Vis spectroscopies with a phenomenological method (that allows assessing average electronic structure parameters) indicate that the gas oil of the West Siberian origin contains polycyclic aromatic hydrocarbons (PAHs) with 3–5 condensed benzene rings. The maximum amount of PAHs with molecular masses of 400–600 a.u. is contained in the fractions with boiling points higher than 450 °C. According to the data of polarized-light optical microscopy, the higher boiling point of the gasoil fraction the higher anisotropy of the produced coke. This occurs as a result of an increase in the amount of PAHs capable of condensation with the formation of a mesophase. Thus, low-sulfur gas oils from thermally processed West Siberian oil are promising raw materials for the production of needle coke in delayed coking processes.

In this study energetic and exergetic performances of parabolic trough collector is theoretically investigated by using 120 l/min synthetic ‘’Dowtherm A’’ oil , 1200 l/min Air at 100 bar (10 MPa) and 150 l/min molten salt which is mixture of 60 wt% sodium nitrate (NaNO3) and 40 wt% potassium nitrate (KNO3) which are widely used as heat transfer fluids. Fluids performance comparisons were performed with the LS-2 module, which is used with vacuum in annulus and Cermet as a selective coating. LS-2 module has 7.8 m receiver length and is 39 m2 aperture area. As a result, the maximum exergy efficiency of the molten salt, synthetic oil, Air to be 41.19% at 422 °C, 40.82% at 400 °C, 40.33% at 402 °C, respectively. The maximum exergy of air is higher than other working fluids up to 310 ° C but after about 310 ° C the exergy of the molten salt is higher than the others. The molten salt has the best energy efficiency at its operating temperatures (250 °C to 550 °C) than other working fluids.

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The solar absorbing materials attract attention for the opto-electronic device applications such as solar cells and photocatalysis. Interest in photocatalytic materials to clean up the wastewater has started to increase. Generally, semiconductors sensitive to UV region are used. However, most of the light from the sun is in the visible region. Cu2CoSnS4 is a promising material that exhibits superior photo-response in the visible regions with an appropriate band gap. In this study, Cu2CoSnS4 films were prepared by the sol–gel method. Cu2Co1–xNaxSnS4 was synthesized for the first time by partly substituting sodium with cobalt. With this approach, noticeable improvements were observed in the physical properties of the material. With the sodium replacement, the Cu2Co1–xNaxSnS4 exhibited high photocatalytic performance toward the degradation of methylene blue (MB) under visible-light irradiation. According to the results, Cu2CoSnS4 and Cu2Co1–xNaxSnS4 samples degraded the MB solution by degradation efficacy values of 89.69% and 94.57%, respectively, in a short time like 40 min under visible light. This study shows that the substitution of sodium boosted the degradation efficiency by 5.4%. For the Cu2CoSnS4 and Cu2Co1–xNaxSnS4 samples, the computed reaction rate constants are 0.059 min−1 and 0.077 min−1, respectively. [ABSTRACT FROM AUTHOR]

In this study, the energy consumption of a vertical closed display refrigerator (680 Liters) in day-night modes and in different product temperature classes was experimentally investigated. Closed display refrigerator works with R290 (propane) refrigerant. Moreover, non-adiabatic capillary tube (suction line heat exchanger) system is used in the vapor compression refrigeration cycle. The experimental setup was carried out and calibrated in accordance with the TS EN ISO 22044:2022 standard. Experiments were carried out for 24 hours in a test room providing a temperature of 25°C ± 0.8°C and a relative humidity of 60% ± 2%. The commercial refrigerator has been tested under full load (700 pcs. 330 ml cans), in day and night modes, and in two different temperature classes (K1 and K4). Can temperatures which tested in the K1 temperature class were kept between 0°C-7°C. These temperature values for the K4 temperature is between 1°C-9°C. In the experiments of the K1 temperature class, 3.255 kWh/24h and 1.379 kWh/24h energy were consumed during the day and night, respectively. In the experiments of K4 temperature class, these values were measured as 3.089 kWh/24h in day mode and 1.341 kWh/24h in night mode. As a result, the energy consumption in the K1 temperature class was 5.37% and 2.83% higher in day and night modes, respectively, compared to the K4 temperature class. [ABSTRACT FROM AUTHOR]

This document is a reply to correspondence regarding a study on oral immunotherapy in alpha-gal red meat allergy. The authors address potential confounding factors for galactose-alpha-1,3-galactose-specific immunoglobulin E positivity (alpha-gal-sIgE), such as asthma, pet ownership, parasites, and medication use. They discuss conflicting findings on the relationship between these factors and alpha-gal sensitivity. The authors also respond to concerns about the impact of biologic therapy on oral immunotherapy and explain the rationale behind the different protocols used in their study. They conclude that further research is needed to understand the risk factors, the impact of therapy, and the mechanisms of oral immunotherapy in alpha-gal allergy. [Extracted from the article]

In this study, the aim is to provide a more detailed understanding of vitamin D metabolism by evaluating the correlation between 1,25-dihydroxyvitamin D (1,25(OH)2D) and 25-hydroxyvitamin D (25(OH)D) according to the variations in measurement methods and clinical conditions.