Synthesis and pesticidal activity of some 4-Azolylmethyl-1,3-dioxolanes, based on cyclic ketones

In vitro tests of substituted 1,3-dioxolanes, based on cyclic ketones and substituted with 1H-1,2,4-triazole and 1H-imidazole showed a fungicidal activity lower than the activity of the triadimefon, and spiroxamine. Studied compounds in the entire concentration range: from 0.001 to 10 mg/L showed noticeable retardant properties. The target compounds were derived by cyclization of substituted cyclohexanones with epichlorohydrin followed by alkylation of the derived 2 chloromethyl-1,3 dioxolanes of sodium salts of imidazole or 1,2,4-triazole.

Estimation of Prediction Error in Regression Air Quality Models

Combustion of energy fuels or organic waste is associated with the emission of harmful gases and aerosols into the atmosphere, which strongly affects air quality. Air quality monitoring devices are unreliable and measurement gaps appear quite often. Missing data modeling techniques can be used to complete the monitoring data. Concentrations of monitored pollutants can be approximated with regression modeling tools, such as artificial neural networks. In this study, a long-term set of data from the air monitoring station in Zabrze (Silesia, South Poland) was analyzed. Concentration prediction was tested for the main air pollutants, i.e., O3, NO, NO2, SO2, PM10, CO. Multilayer perceptrons were used to model the concentrations. The predicted concentrations were compared to the observed ones to evaluate the approximation accuracy. Prediction errors were calculated separately for the whole concentration range as well as for the specified concentration subranges. Some different measures of error were estimated. It was stated that the use of a single measure of the approximation accuracy may lead to incorrect interpretation. The application of one neural network to the entire concentration range results in different prediction accuracy in various concentration subranges. Replacing one neural network with several networks adjusted to specific concentration subranges should improve the modeling accuracy.

Magnetodielectric properties of ferrite-piezoelectric composite materials.

Ceramic composite materials based on compounds of lead zirconate-titanate and cobalt ferrite with different content of the initial components mass fraction have been synthesized. Using a complex of physicochemical methods, the microstructure and magnetodielectric properties of the synthesized ceramics have been studied. The resulting frequency dependences of the magneto-dielectric coefficient for the composite system (1-x)PZT + xCF(0.0 ≤ x ≤ 0.5) in an external magnetic field have a resonance form in the entire concentration range investigated. The largest changes in the value of the complex permittivity are observed for the sample with the composition of 0.6PZT + 0.4CF.

Enhancement of heat transfer for boiling in nanofluid

The paper considers heat transfer during boiling of subcooled water with suspended nanoparticles Al2O3 using a suspension from 0.32% to 4%. On a spherical model, the local heat flux per unit area was measured by the method of gradient heatmetry for model temperature of 464 °C and water temperature of 64 °C. The results are compared with the data obtained at the same temperature conditions for pure water. Enchancement of heat transfer was revealed in the entire concentration range - with a maximum at a particle concentration close to 1%.

Long-term antibacterial activity of vancomycin from calcium phosphate cement in vivo

BACKGROUND: Periprosthetic joint infection is a major complication of total joint arthroplasty, with treatment requiring a two-stage exchange procedure and 6 weeks of systemic antibiotics. However, depending on the infection site, intravenous delivery of antibiotics like vancomycin (VCM) can have poor tissue transferability, thus reducing their therapeutic effect. OBJECTIVE: This study demonstrates the 24-week in vivo release profile and antibacterial activity of VCM from calcium phosphate cement impregnated with VCM (CPC/VCM) and compares them with those from polymethylmethacrylate impregnated with VCM (PMMA/VCM). METHODS: Rats were implanted with the test specimens between the fascia and quadriceps. After implantation for 24 weeks, the test specimens were removed and residual VCM was extracted to calculate the concentration of VCM released into rat tissues. We also examined the antibacterial activity of releasable VCM from the removed test specimens by placing them directly onto the surface of agar. RESULTS: CPC/VCM released greater concentrations of VCM for a longer period of time within the 24 weeks than PMMA/VCM. Moreover, CPC/VCM released 1.4 to 26.1-fold more VCM than PMMA/VCM. Using Staphylococcus aureus, antibacterial activity was logarithmically correlated with VCM concentration across the entire concentration range tested (12.5–800 μg/mL). While the area within which inhibition was observed—the inhibition zone—for both CPC/VCM and PMMA/VCM formed and gradually shrank with time after implantation, that for CPC/VCM was significantly larger than that for PMMA/VCM in each week after implantation. CONCLUSION: CPC/VCM releases greater amounts of VCM with antibacterial activity for longer periods of time than PMMA/VCM, suggesting that CPC is effective for facilitating the release of antibiotics for local action in patients with established postoperative infection.

Time Domain Reflectometric Studies on Methylcellosolve – Acetylacetone Binary Solutions

Time Domain Reflectometric studies has been applied on the binary solutions of methylcellosolve (MCS) with acetylacetone (ACACT) in the entire concentration range at 298 K in the frequency range of 10 MHz – 32 GHz. The values of relaxation time (τ), effective Kirkwood correlation factor (geff ), corrective Kirkwood correlation factor (gf ) and excess permittivity (εE ) have been calculated. The relaxation time of MCS slowly decreases with increase in ACACT concentration suggesting that the size of the heteroassociated rotating unit decreases. The rate at which τ value decreases is more in MCS rich solutions which means that the formation of heteromolecular H – bonds dominantly occur in MCS rich solutions. Parallel orientation among the dipoles occur as suggested by the g^eff values which are greater than unity in all the solutions. The excess permittivity ε^E values calculated using mole and volume fractions qualitatively exhibit the same deviation from ideal behaviour.

The Mixed Hydrogen Bonds Network in a Liquid System Ethylene Glycol-Monoethanolamine

The mixed network of hydrogen bonds in the ethylene glycol (EG) - monoethanolamine (MEA) system is described by molecular dynamics (MD) methods, graph theory, and Delaunay simplexes at 300 K in the entire concentration range. It is shown that at low MEA concentrations, all molecules in the system are linked into a spatial network of H-bonds; at high MEA concentrations, this number is 96%. Detailed characteristics of the networks are given. The resulting picture is expanded by studying the system using the Delaunay simplex method. The calculations are compared for different charges on the atoms of the MEA molecule.

Thermodynamics of formation and evaporation of lead-tin alloys

Only a few works have been devoted to thermodynamic studies of the lead-tin system by methods including the volatile components evaporation process. When the binary system is separated into metals by distillation, the volatile component is removed from the alloy and the low-volatile component accumulates in the bottom products, that is, there are alloy composition changes over the entire concentration range. It is necessary to know the boundaries position of the melt and vapor coexistence fields on the state diagram, especially for solutions beneficiated with non-volatile metal to assess the quality of the vapor phase by the content of the low-volatile component. In this regard, the study has been completed with the purpose to clarify the values of the thermodynamic functions of the formation and evaporation of lead-tin melts required to calculate the boundaries of the liquid and vapor coexistence fields on the state diagram that enables us to judge the amount of a low-volatile component in the vapor phase under equilibrium conditions. The thermodynamic activity of lead was calculated, as well as the numerical integration of the Gibbs-Duhem equation using the substitution proposed by Darken is the thermodynamic activity and pressure of saturated tin vapor Based on the values of the saturated lead vapor pressure, determined by the boiling point method (isothermal version) for alloys predominantly of the lead edge of the phase diagram. The thermodynamic constants thus obtained will add to the base of physicochemical data and will be used to calculate the boundaries of the vapor-liquid equilibrium fields on the phase diagram, allowing to determine the possibility and completeness of the distillation separation of metals.

ДОСЛІДЖЕННЯ ВПЛИВУ СТИРОЛ-АКРИЛОВИХ ПОЛІМЕРІВ НА ФІЗИКО-МЕХАНІЧНІ І ГІГІЄНІЧНІ ВЛАСТИВОСТІ БАВОВНЯНОЇ ТКАНИНИ

The purpose of the work is to study the effect of styrene-acrylic polymer coatings on the change in physical, mechanical and hygienic properties of cotton fabric. Aqueous dispersions of styrene-acrylic polymers (Lacrytex 640, Akratam AS 02.1, Tubifast AS 4010) were selected as the object of study. The processing of cotton fabric was carried out by the method of impregnation with varying a concentration of the studied polymers in finishing bath from 50 g/l to 150 g/l, followed by drying and heat setting. Standardized methods for studying the properties of textile materials were applied. The effect of polymer coatings on the physical and mechanical properties of cotton fabric was evaluated by the indicators of weight gain, thickness and rigidity. The hygienic properties of treated cotton fabric were characterized by hygroscopicity and breathability. The paper presents the results of a study of the dependence of physical, mechanical and hygienic properties of cotton fabric on the type and concentration of styrene-acrylic dispersions used. According to the results of the experiment, it was found that the acrylic copolymer Lacrytex 640 increases the elastic properties of treated fabric in the entire concentration range studied. It was determined that the greatest decrease in air permeability is typical for fabric samples coated on the basis of Akratam AS 02.1 dispersion. The hygroscopicity of cotton textile material with an increase in a concentration of the studied styrene-acrylic polymer dispersions from 50 g/l to 100 g/l decreases slightly (by 2%). It is proved that the styrene-acrylic copolymer Tubifast AS 4010 due to the formation of highly elastic film provides a soft handle and high hygienic properties of cotton fabric. The obtained experimental results are of practical value in the development of new finishing compositions for textile materials.