Study of Triple System Calcium Iodide-HMTA-Water

Research relevance: synthesis, physicochemical studies of complexes bioactivity with salts of biometals and organic ligands are of great interest for bio-coordination chemistry. Materials and research methods: isothermal method was used to study heterogeneous equilibria at 25 °C. The concentration limits of compounds existence and the types of their solubility have been established. Research objectives: to investigate compounds of hexamethylenetetramine with salts of biometals with organic ligands in order to reduce toxicity, increase the bioactivity and bioavailability of coordination compounds. Research results: concentration limits of compounds existence and types of their solubility have been established. Conclusions: in obtained complexes, HMTA ligand contains four equivalent electron donor nitrogen atoms.

The Physicochemical Analysis of Bayerite Al(OH)3 → γ-Al2O3 Transformation

It was obtained aluminum hydroxide in the form of bayerite by precipitation with ammonia. The precipitation pH was found by the potentiometric titration. Based on the data of thermal, X‑ray diffraction and IR‑analysis it was identified the sequence of bayerite transitions up to 800 °C. The study of nitrogen adsorption- desorption allowed to determine a specific surface, a volume, and dimensions of pores for boehmite and γ- Al2O3 as 135±2 and 238±10 m2/g; 0.38 and 0.51 cm3/g; 1.7 and 3.8 nm, relatively. The value of effective activation energy for boehmite →γ- Al2O3 transition ((136±5) kJ/mol) was found by means of non- isothermal method (by Avrami equation)

ISOTHERM OF SOLUBILITY MANGANESE SULFATE - MONOETHANOLAMINE - WATER AT 25 ° C

Solubility in the ternary system manganese sulfate - monoethanolamine - water at 25°C was studied by isothermal method. The equilibrium in the system was controlled by liquid phase analysis. True equilibrium in the system was established within 7 hours. The new compound was isolated in crystalline form and identified by the methods of chemical, graphic, X-ray and thermal analyses. It was found that the new compound is a crystalline substance with an individual set of interplanar distances and line intensities. The formation of the new compound NH2C2H4ON-MnSO4-3H2O which was identified by the methods of chemical, graphic and X-ray analyses has been established. Preliminary agrochemical tests of aqueous solution of the new compound showed its positive properties as a stimulant.

DEFORMATION OF ALUMINUM ALLOYS IN ISOTHERMAL CONDITIONS

It has been scientifically proven that aluminum, more than other materials, meets the requirements of production, storage and processing of various foods. Therefore, the prospects for its use in the agro-industrial complex are quite high. At the same time, the process of developing such materials should be improved and promoted. Aluminum alloys are widely used in the aviation industry, in mechanical engineering and in agricultural production, due to their properties and light metal consumption. Alloys are resistant to water, they are not afraid of corrosion, sunlight, easily disinfected. All these properties are best suited for the use of aluminum in the storage of both cereals and livestock products. Moisture, dangerous molds, rodents and various insects are released and absorbed in storage. Aluminum has a high thermal conductivity and reflectivity, which reduce the risk of moisture condensation, which normalizes storage. The smoothness of this material suggests that the walls of aluminum structures collect much less dust. The proposed isothermal method of hot deformation of aluminum alloys in the processing of metals by pressure, differs from traditional deformation, and the temperature of the heated workpiece and the deforming tool is kept constant, close to the upper limit of forging temperatures, throughout the process. The deformation of the metal under isometric conditions and approximate deformations is characterized by an increase in ductility compared with ductility when machined in a cold tool. This is due to the lower rate of deformation, the lower limit of which is limited only by the productivity of the process. As a result, the "filling time" of defects that occur during metal deformation increases, the temperature stress in the workpiece volume decreases, the deformation becomes more uniform.

Assessment of the stepped isothermal method for accelerated creep testing of high-density polyethylene

Thermoplastic materials are increasingly used in demanding structural applications under, in some cases, long-term static loading over several decades. In this regard, the stepped isothermal method (SIM) with creep testing at stepwise increased temperature levels in combination with time-temperature superposition (TTSP) provides a very time efficient procedure for long-term creep characterization. In the present study, the creep behavior of an injection molded high-density polyethylene material (HDPE) was investigated by SIM in the thermally untreated state as well as after annealing.Due to experimental issues regarding the heating behavior of the specimens and non-linear viscoelastic behavior, particularly at elevated temperatures, bi-directional curve shifting was required in order to generate meaningful master curves for creep compliance. In a first step, an Arrhenius equation was used for the horizontal curve shifting, based on activation energies, determined in additional multi-frequency dynamic mechanical analysis (DMA). Continuous master curves were then obtained by empirical vertical shifting of the individual creep curve segments for the different temperature levels. In general, good agreement was observed between the resulting SIM master curves and the corresponding conventionally measured creep compliance curves at least for a time range up to 300 hours. Furthermore, significant differences in the creep tendency of the annealed material state compared to the thermally untreated condition revealed the distinct influence of the thermal history on the resulting creep behavior.

Ultrarapid detection of SARS-CoV-2 RNA using a reverse transcription–free exponential amplification reaction, RTF-EXPAR

A rapid isothermal method for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19, is reported. The procedure uses an unprecedented reverse transcription–free (RTF) approach for converting genomic RNA into DNA. This involves the formation of an RNA/DNA heteroduplex whose selective cleavage generates a short DNA trigger strand, which is then rapidly amplified using the exponential amplification reaction (EXPAR). Deploying the RNA-to-DNA conversion and amplification stages of the RTF-EXPAR assay in a single step results in the detection, via a fluorescence read-out, of single figure copy numbers per microliter of SARS-CoV-2 RNA in under 10 min. In direct three-way comparison studies, the assay has been found to be faster than both RT-qPCR and reverse transcription loop-mediated isothermal amplification (RT-LAMP), while being just as sensitive. The assay protocol involves the use of standard laboratory equipment and is readily adaptable for the detection of other RNA-based pathogens.

A Review on the Efficiency of NASBA Molecular Technique for Diagnosis of Acute Toxoplasmosis in Pregnant Mothers

Introduction: Toxoplasmosis is a worldwide disease caused by an intracellular protozoan called Toxoplasma gondii and in mothers who become infected during pregnancy, it can cause serious damage to the fetus by passing through the placenta. The aim of this study was to review the effectiveness of the NASBA molecular technique in diagnosing the acute form of Toxoplasmosis in pregnant mothers. Material and Methods: In this study, the websites of PubMed, Google Scholar, SID, Magiran, Web of Science, IranDoc were searched and articles related to the title have been reviewed from 1990 to 2020. Results: Nucleic Acid Sequence-Based Amplification (NASBA) is an isothermal method that has the processes of nucleic acid extraction, amplification, and identification of amplified products. This technique is based on transcription and is specifically used for RNA amplification, so it is highly specific in identifying living and active microorganisms. All steps in this amplification method are performed at 41 °C and the amplified products can be identified by appropriate detection methods such as electrochemical luminescence (ECL). Conclusion: Since all steps of amplification are performed by NASBA at the same temperature of 41°C, unlike molecular PCR technique, a thermocycler is not required, so setting it up will not cost much for laboratories and it can be useful in providing a suitable solution for toxoplasmosis screening in pregnant mothers.

CFD Performance Analysis of a Dish-Stirling System for Microgeneration

The sustainable transition towards renewable energy sources has become increasingly important nowadays. In this work, a microgeneration energy system was investigated. The system is composed of a solar concentrator system coupled with an alpha-type Stirling engine. The aim was to maximize the production of electrical energy. By imposing a mean value of the direct irradiance on the system, the model developed can obtain the temperature of the fluid contained inside the Stirling engine. The heat exchanger of the microgenerator system was analyzed, focusing on the solar coupling with the engine, with a multiphysical approach (COMSOL v5.3). A real Stirling cycle was implemented using two methods for comparison: the first-order empirical Beale equation and the Schmidt isothermal method. Results demonstrated that a concentrator of 2.4 m in diameter can generate, starting from 800 W/m2 of mean irradiance, a value of electrical energy equal to 0.99 kWe.