Hydrothermal Treatment of Arsenopyrite Particles with CuSO4 Solution

The nature of the hydrothermal reaction between arsenopyrite particles (FeAsS) and copper sulfate solution (CuSO4) was investigated in this study. The effects of temperature (443–523 K), CuSO4 (0.08–0.96 mol/L) and H2SO4 (0.05–0.6 mol/L) concentrations, reaction time (1–120 min), stirring speed (40–100 rpm) and particle size (10–100 μm) on the FeAsS conversion were studied. The FeAsS conversion was significant at >503 K, and it is suggested that the reaction is characterized by the formation of a thin layer of metallic copper (Cu0) and elemental sulfur (S0) around the unreacted FeAsS core. The shrinking core model (SCM) was applied for describing the process kinetics, and the rate of the overall reaction was found to be controlled by product layer diffusion, while the overall process was divided into two stages: (Stage 1: mixed chemical reaction/product layer diffusion-controlled) interaction of FeAsS with CuSO4 on the mineral’s surface with the formation of Cu1+ and Fe2+ sulfates, arsenous acid, S0, and subsequent diffusion of the reagent (Cu2+) and products (As3+ and Fe2+) through the gradually forming layer of Cu0 and molten S0; (Stage 2: product layer diffusion-controlled) the subsequent interaction of CuSO4 with FeAsS resulted in the formation of a denser and less porous Cu0 and S0 layer, which complicates the countercurrent diffusion of Cu2+, Cu1+, and Fe2+ across the layer to the unreacted FeAsS core. The reaction orders with respect to CuSO4 and H2SO4 were calculated as 0.41 and −0.45 for Stage 1 and 0.35 and −0.5 for Stage 2. The apparent activation energies of 91.67 and 56.69 kJ/mol were obtained for Stages 1 and 2, respectively.

Vеterinary and sanitary assessment of meat of foals of the Oymyakonsky region of Sakha (Yakutia) Republic at helminthoses

This article presents data on the spread of horse helminth infestations in the Oymyakonsky region, postmortem examination of carcasses and organs of foals, as well as organoleptic, physical and chemical, microbiological studies of meat of foals slightly and strongly infested with helminths in a comparative aspect. According to the results of organoleptic studies of meat from weakly invaded foals meet the requirements of GOST -7269-79, GOST 32225-2013 and can be consumed as food without restrictions. Meat from heavily invaded animals differs from weakly invaded animals in organoleptic indicators. The meat has a red crust of dried carcass, folded, slightly moist, the muscles on the cut are moist, but don't leave a damp spot on the filter paper, expressed red color. The consistency of the muscle is tight, elastic, the dimple formed by pressing with the finger is slowly smoothed out. The smell of the meat is peculiar to that of foals. The fat is soft, slightly sticky and yellowish. The broth is cloudy, with flakes. Physico-chemical investigations showed that meat samples from weakly invaded foals meet the requirements of normative documents GOST R-51478-99, GOST-23392-78. During the comparative evaluation of the meat of weakly invaded and heavily invaded, the following indicators were established: peroxidase reaction - "positive", aminoammonia nitrogen content - 0.84, pH - 5.8. When adding copper sulfate solution to the broth under study, insignificant flakes appeared, while maintaining broth transparency - the reaction is "doubtful". In heavily invaded foals, meat quality does not meet GOST: peroxidase reaction is "negative", reaction with copper sulfate is dubious, meat broth is turbid, with flakes; aminoammoniacal nitrogen content is 1.4, pH - 6.2. The results of microbiological investigations of the meat of weakly invaded foals meet the requirements of normative documents GOST-32031-2012, GOST-10444.15-94. Detected in the meat of heavily invaded foals BSCP (coliforms), KMAFANM (coliforms) - 8*103, indicating that the meat obtained from heavily invaded foals on microbiological indicators, the established standards do not correspond. Consequently, the indicators of meat of weakly invaded foals correspond to fresh, good-quality meat, and the meat of heavily invaded foals is recommended for use in food after industrial processing.

Copper Oxide Decorated Zinc Oxide Nanostructures for the Production of a Non-Enzymatic Glucose Sensor

The glucose concentration in human blood can have a worrisome impact on human health, so the distribution of blood glucose contaminants in the human body is an important indicator that can be used to monitor diabetes. Diabetes affects many parts of the human body, such as neurological impairment, erectile dysfunction, and hardening of the arteries resulting in organ loss. In this study, cyclic voltammetry (CV) was used to process the electrical properties of a solution by preparing electrodes with CuO nanoparticles modified ZnO tetrapod nanostructures deposited on fluorine-doped tin oxide glass (CuO/ZnO/FTO). The measurements were processed in glucose solutions of different concentrations purposing for developing the sensitivity of the sensor. Different immersion times in the precursor copper sulfate solution were also used for preparing the electrode and carried out for electrochemical studies to adjust the electrode capability. The modified electrode, which was immersed in copper sulfate for 30 s, was efficient in detecting glucose molecules in different concentrations at the potential of +0.6 V. The rising slope is strongly and positively correlated with the concentration of glucose. One of the significant results is the indication that glucose concentration is linearly proportional to the current value of CV. After the measurement test with the addition of interference, the sensor can still identify the glucose concentration in the solution without being affected. This result proves that the sensor has considerable potential for developing into a high-performance non-enzymatic glucose sensor.

Electroplating of copper/microdiamond composites and the effect of diamond surface functionalization

Compositing diamonds with high thermally conductive metals, such as copper, have attracted much attention in recent years. In this study, we prepared copper/diamond composites by electroplating and investigated the effect of the surface functionalization of diamond on the interfacial adhesion of copper and diamond in the composite. Oxygen-containing groups were introduced on the diamond surface by a hydrothermal treatment and amino groups were further introduced using a silane coupling agent. Surface functionalization of diamond with both these groups led to drastically increased wettability against the copper sulfate solution and improved the interfacial adhesion of copper and diamond in the composite. Compared with that of the plating based on pristine diamond, the thermal conductivity of the platings based on diamond functionalized with oxygen-containing groups and amino groups increased by 42 and 31 W m[Formula: see text] K[Formula: see text], respectively. Thus, diamond surface functionalization effectively improved the adhesion at the copper/diamond interface in electroplated copper/diamond composites.

The Effect of Cu (II) on Swelling and Shrinkage Characteristics of Sodium Bentonite in Landfills

Wastes in municipal landfills will release heavy metal cations over a long period of time. Therefore, the objective of this paper was to investigate the effect of copper (Cu) in the leachate from landfill on the swell-shrinking potential of bentonite liner. Copper sulfate solution with 4 different groups of concentrations (0 g/L, 2.5 g/L, 5 g/L, 10 g/L) were added to bentonite for conducting a series of swelling and shrinkage experiments. Then the Does Response model was used to describe the swelling and shrinkage process of bentonite in different copper sulfate solutions and the applicability of the model was evaluated. At the same time, clay mineral analysis experiments (XRD and XRF) were carried out to analyze the variation of interlayer space and element content of montmorillonite. The results show that the swell volume of bentonite decreases with the increase of the concentration of Cu (II). The rate of swelling was high and inversely proportional to the concentration of Cu (II). The shrinkage curve of bentonite could be divided into uniform velocity stage, variable velocity stage, and stable stage. The shrinkage rate at the uniform velocity stage and shrinkage at the stable stage decreased with the increase of the concentration of Cu (II). The model was suitable for describing swelling (or shrinkage) curves with smaller expansibility (or shrinkage). Results of XRD and XRF show that the erosion of Cu (II) led to the decrease of Na+ content in sodium bentonite, and then narrowed interlayer space of montmorillonite. When the solution concentration increases, both values of interlayer space of montmorillonite and Na+ content in sodium bentonite become lower, and that led to swelling and shrinkage of bentonite liner was getting smaller and smaller.

Multi-mode states in quasi-two-dimensional rotating flows

<p>The idea of the multiplicity of equilibrium states of the atmospheric circulation in geophysical hydrodynamics goes back to Charne and DeVore 1979, where, for a model with a small number of variables, solutions with significantly different values of the zonal and wave velocity components were obtained (see also Laurie, Bouchet 2015, Herbert et al. 2020). The results of similar studies for low-parameter approximations were given by Kallen 1980, Gluhovsky 2001, Koo, Ghil 2002 ... The circulation modes differed in the magnitude of the zonal component of the flow. At weak transport, the role of almost stationary atmospheric eddies is enhanced, which corresponds to circulation blocking modes. Laboratory confirmation of the effect was obtained from Weeks et al. 1997, Tian et al. 2001.</p><p>In the same years, in the experiments of A.M. Obukhov and coworkers, modes with differently directed axes of large-scale fluid rotation were observed in closed vessels at the same value of external generation - Obukhov et al. 1976, Gledzer et al. 1981.</p><p>In the present study, supported by Russian Science Foundation (Project 19-17-00248), the above types of multi-mode are considered based on laboratory and numerical experiments in circular rotating channels. It is known that the permanent magnet location configurations (source-sinks) could create an almost stationary vortex distribution pattern Gledzer et al. 2013,2014. The transition between different states is provided by a change in the value of the main parameter of electric current generation with subsequent restoration of its initial value.</p><p>The experimental results presented below are obtained for a rotating annular channel (rotation periods up to 1 minute) filled with an electrically conductive 10% copper sulfate solution. The bottoms of circular channels with inner and outer radii of 1) 5.5 cm and 18 cm  2) 5 cm and 36 cm have an axisymmetric conical shape with a height of 1 cm.</p><p>Depending on channel rotation periods or source configurations, it is possible: 1) Initial and final modes differ quantitatively in the number of generated vortices. 2) The number of vortex formations does not change, but differ in their spatial localization. 3) After changing and restoring the value of the defining parameter, the flow returns to the mode which is practically the same as the initial one.</p><p>Numerical experiments with the shallow water model confirmed the results obtained in laboratory experiments on the possibility of transition to new modes when the parameter determining the external force is changed for some time. For the source-sink method, a change in the number of large vortices (cyclones) is observed. At MHD generation it is possible to detect a change in the finite spatial position of vortices with preservation of their number.</p><p>Experiments support the conclusion that different modes of barotropic dynamics may exist. And it is unlikely to be associated with any low-parameter approximation of the velocity field in the model.</p><p>In our and earlier experiments and models, multi-mode is a property of dynamics in general. The mechanism of multi-mode may be an alternative to the traditional scenario of transition to other modes when external conditions change.</p>

Effects of Electrolyte on Laser-Induced Periodic Surface Structures with Picosecond Laser Pulses

Short-pulsed laser-induced periodic surface structures (SPLIPSSs) have the possibility to control tribology, wettability and biocompatibility. Nevertheless, the optimal structure depends on each functionality, which has not been clarified. The hybrid process with a short-pulsed laser and electrochemical machining (SPLECM) is, then, proposed to fabricate micro/nano hybrid structures and to modify the surface composition for providing high functionalities with material surfaces. Electrochemical machining is a well-established micro-elution and deposition method with noncontact between a workpiece and a tool. In this study, the effects of electrolytes on SPLIPSSs were investigated experimentally by the picosecond laser irradiation on 304 stainless steel substrates in various electrolytes. The geometry of SPLIPSSs depended on the types and the concentration of electrolytes. In the case of copper nitrate solution and copper sulfate solution, LIPSSs and spheroidization of copper were obtained. This study demonstrated the possibility of SPLECM to fabricate micro/nano structures and to control surface composition.

Migration, Crystallization and Dissolution Changes of Salt Solution with Color Rendering Property in Porous Quartz Materials

In order to visually display the migration and crystallization process of salt solution in porous cultural relics, copper sulfate solution with color rendering property was selected to record the migration, crystallization and resolution of salt solution in simulated SiO2 samples under different environmental conditions in real time through high-resolution recording system, scanning electron microscope system, salt phase X-ray diffraction system, and so on. The results showed the migration of salt solution in porous samples was related to the structural characteristics of the porous samples, the migration rate of salt solution, the evaporation rate and the change frequency of crystallization–resolution, etc., in which the large pore size of the sample, the higher the concentration and the faster migration and evaporation rate of salt solution, the greater the change rate of the brine accumulation zone or salt crystallization zone in the different porous samples. During the humidification–drying cycles of rainfall, the higher the cycle frequency of humidification–drying was, the higher the drying temperature was, the more frequent the crystallization-analysis change of salt in the salt-bearing sample was, and the more extensive the distribution of salt crystal zone was. This is the first time to visualize the salt belt by simulating the changing process of a salt solution with a color rendering property in porous samples. This has scientific theoretical guidance for the study of the migration–crystallization changes of soluble salts contained in porous silicate cultural relics. The visibility analysis results of multilayer salt crystal belts can also provide the preliminary basis for further effective desalination of salt bearing cultural relics.