The Influence of Polysaccharides/TiO2 on the Model Membranes of Dipalmitoylphosphatidylglycerol and Bacterial Lipids

The aim of the study was to determine the bactericidal properties of popular medical, pharmaceutical, and cosmetic ingredients, namely chitosan (Ch), hyaluronic acid (HA), and titanium dioxide (TiO2). The characteristics presented in this paper are based on the Langmuir monolayer studies of the model biological membranes formed on subphases with these compounds or their mixtures. To prepare the Langmuir film, 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DPPG) phospholipid, which is the component of most bacterial membranes, as well as biological material-lipids isolated from bacteria Escherichia coli and Staphylococcus aureus were used. The analysis of the surface pressure-mean molecular area (π-A) isotherms, compression modulus as a function of surface pressure, CS−1 = f(π), relative surface pressure as a function of time, π/π0 = f(t), hysteresis loops, as well as structure visualized using a Brewster angle microscope (BAM) shows clearly that Ch, HA, and TiO2 have antibacterial properties. Ch and TiO2 mostly affect S. aureus monolayer structure during compression. They can enhance the permeability of biological membranes leading to the bacteria cell death. In turn, HA has a greater impact on the thickness of E. coli film.

Effect of Vinyl-Terminated Silicone Oil Chain Length and Reinforcing Agent on the Properties of Silicone Rubber

To solve the problems of low strength and high viscosity of room temperature vulcanized liquid silicone rubber, a series of terminated vinyl silicone oil were designed and synthesized, and low viscosity and high strength silicone rubber were prepared by the mechanical reinforcing agent. the results show that the molecular structure of the vinyl-terminated silicone oil has a significant effect on the mechanical properties and viscosity of the silicone rubber, and the best performance is found when the content of vinyl-terminated silicone oil is 0.16%. The low viscosity and high strength silicone rubber prepared from it was reinforced by vinyl MQ resin and fumed silica, which had a significant effect on improving the performance. Its tensile strength increased to 5.03 MPa, elongation at break to 338.90%, and tear strength to 7.15 kN/m compared to conventional silicone rubber, while the hardness increased to 43°. The viscosity is 34.9 Pa•s. The compression modulus is 7.48 MPa.

A simulation strategy to determine the mechanical behaviour of cork-rubber composite pads for vibration isolation

The present work aimed to determine the performance of new cork-rubber composites, applying a modelling-based approach. The static and dynamic behaviour under compression of new composite isolation pads was determined using mathematical techniques. Linear regression was used to estimate apparent compression modulus and dynamic stiffness coefficient of compounds samples based on the effect of fillers, cork and other ingredients. Using the results obtained by regression models, finite element analysis (FEA) was applied to determine the behaviour of the same cork-rubber material but considering samples with different dimensions. The majority of the regression models presented R2 values above 90%. Also, a good agreement was found between the results obtained by the presented approach and previous experimental tests. Based on the developed methodology, the compression behaviour of new cork-rubber compounds can be accessed, improving product development stages.

THERMODYNAMIC PROPERTIES AND THE EQUATION OF STATE OF COPPER

Высокотемпературное уравнение состояния меди получено с использованием экспериментальных данных по термодинамическим свойствам, объемному термическому расширению, сжимаемости, температурной зависимости модуля объемного сжатия. Весь объем экспериментальных данных оптимизирован с использованием температурно-зависящего уравнения Тайта в диапазоне давлений до 2000 кбар и температур от 20-50 K до температуры плавления. Температурная зависимость термодинамических и термофизических параметров описана с использованием расширенной модели Эйнштейна. Полученное уравнение состояния хорошо описывает весь объем экспериментальных данных в пределах погрешности измерений отдельных величин. The high-temperature equation of state of copper is obtained using experimental data on thermodynamic properties, volumetric thermal expansion, compressibility, temperature dependence of the volumetric compression modulus. The entire volume of experimental data is optimized using the temperature-dependent Tate equation in the pressure range up to 2000 kbar and temperatures from 20-50 K to the melting point. The temperature dependence of thermodynamic and thermophysical parameters is described using the extended Einstein model. The resulting equation of state describes well the entire volume of experimental data within the measurement error of individual quantities.

THERMODYNAMIC PROPERTIES AND THE EQUATION OF STATE OF LEAD

Институт проблем химико-энергетических технологий Сибирского отделения Российской академии наук (ИПХЭТ СО РАН), г. БийскВысокотемпературное уравнение состояния (УС) твердого свинца с гранецентрированной кубической структурой решетки получено с использованием экспериментальных данных по термодинамическим свойствам, термическому расширению, сжимаемости, температурной зависимости модуля объемного сжатия. Весь объем экспериментальных данных оптимизирован с использованием температурно-зависящего УС Тайта в диапазоне давлений 0-130 кбар. Температурная зависимость термодинамических и термофизических параметров описана с использованием расширенной модели Эйнштейна. Полученное УС хорошо описывает весь объем экспериментальных данных в пределах погрешностей измерения отдельных величин. The high-temperature equation of state (US) of solid lead with a face-centered cubic lattice structure is obtained using experimental data on thermodynamic properties, thermal expansion, compressibility, and temperature dependence of the volume compression modulus. The entire volume of experimental data is optimized using a temperature-dependent Void in the pressure range 0-130 kbar. The temperature dependence of thermodynamic and thermophysical parameters is described using the extended Einstein model. The obtained US well describes the entire volume of experimental data within the measurement errors of individual quantities.

Effects of Oil Contamination on the Physical-Mechanical Behavior of Loess and Its Mechanism Analysis

Oil leakage will not only pollute the soil but also change its physical-mechanical behavior, and loess has complex properties in the environment of oil presence. Artificial loess contaminated by diesel oil is collected as the research object. The physical and mechanical properties of clean loess and contaminated loess, including liquid and plastic limits, permeability, compression properties, and compressive strength characteristics, are estimated through a series of laboratory tests under different oil contents, water contents, and dry densities. Results show that liquid limits, plastic limits, and permeability coefficient of diesel-contaminated loess decrease with the increase of oil content. The compression modulus and compressive strength of diesel-contaminated loess increase with the increase of dry density at the same oil content. Adding diesel oil, the change law of the unconfined compressive strength of contaminated loess is opposite at the two different water contents. The variation of the compression modulus and unconfined compressive strength of diesel oil-contaminated loess is basically identical at the same condition. The findings of this study would be expected to bridge the gap between theory and practice in treatment and remediation of contaminated soil in the region of oil production.

Study of Langmuir monolayers and Langmuir-Schaefer films based on symmetrical meso-aryl-substituted porphyrin derivative

This paper presents the results of a study of meso-aryl-substituted porphyrin Langmuir monolayers by the method of compression isotherms. Experimental data were used to plot the dependences of the compression modulus (C−1) on the specific area. Monolayers at specific surface pressure were transferred to solid substrates and investigated. The monolayers were transferred to the surface of monocrystalline silicon at surface pressures of 8, 25, and 60 mN/m and examined them by atomic force microscopy (AFM) in a semi-contact mode. It was found that with an increase in the transfer pressure, the coarsening of molecular aggregates occurs. The smallest roughness is observed for a porphyrin film formed and transferred at a pressure of 8 mN/m.

The synergistic effect of SiC/R-GO composite on mechanical and tribological properties of thermosetting polyimide

The effective means to solve material wear is to develop self-lubricating composite materials with excellent tribological, thermal, and mechanical properties. Herein, the composites of reduced graphene oxide (r-GO) nanosheet decorated with Silicon Carbide (SiC) were facilely prepared with employing a silane coupling agent, and the corresponding r-GO/SiC/thermosetting polyimide (r-GO/SiC/TPI) nanocomposite films were obtained by in situ polymerization method. The mechanical, tribological, and thermal properties of these nanocomposite films were investigated. When the content of r-GO/SiC was at 1.0 wt%, the compression strength and compression modulus of the composite increased by 37.7% and 47.3%, respectively, which were much higher than that of TPI composites addition of r-GO or SiC alone. Furthermore, r-GO/SiC/TPI composites also exhibited the lowest wear rate and friction coefficient in these reinforced TPI nanocomposites. When the content of r-GO/SiC was 0.8 wt%, particularly, the friction coefficient and wear rate of r-GO/SiC/TPI decreased by 22.8% and 79.8% compared to pure TPI, respectively. Additionally, trace amount r-GO/SiC hybrids also significantly enhance the thermal stability of TPI matrix. Compared to the polyimide composites reinforced by common nano-scale inorganic fillers, the outstanding mechanical and tribological properties of this r-GO/SiC/PI composites could be attributed to the ball on plane structure of GO/SiC, which lead to crack reflection, strength increment. These r-GO/SiC/TPI composites demonstrate the promising potential to be used as high-performance tribological materials in industry applications.

Testing the magnetoactive elastomer sample for compression with the test machine

A sample of a magnetoactive silicone composite with ferromagnetic fillers is examined on a testing machine. The dependences of the change in the values of the moduli of longitudinal elasticity on deformation are plotted for various modes of compression of the sample. The characteristics of the linear and nonlinear dynamics of changes in the moduli of longitudinal elasticity are given as a function of the magnitudes of the deformations of the material during compression. Within the limits of deformation of the sample, which is 24% of its height, the moduli of longitudinal elasticity are linear. The nonlinear nature of the change in the compression modulus occurs when the sample is deformed over 40%. When the compression ratio of the sample was up to 72%, the compression modulus increased by a factor of 9 without the action of a magnetic field and by a factor of 22 under the action of a magnetic field. The influence of the magnetic field on the growth of the compression moduli with the increase in the compression force ranges is shown. The property of the material to self-healing (“shape memory”) was established after testing in the mode of maximum compression of ultimate loads.

The Mechanical Properties and Microstructure of Reticulated Red Clay-Sand Mixture Using X-Ray Diffraction

To assess the behavior of Reticulated Red Clay (RRC)-sand mixtures, a series of laboratory tests were performed on RRC-sand mixtures in which the weight ratio of sand ranging from 0% to 80%. Compaction test and direct shear test were conducted to evaluate the compactness of mixtures. The threshold sand content for the change of the mechanical properties of the mixture is 50%, and the mixture at this time has the densest structure. Oedometer test to the mixture indicate that the coefficient and compression modulus of it are only related to the ratio of its components. As the sand content in the mixture increases, the phenomena that the clay particles enclosing the sand particles and filling into the gaps of particles make the mixture denser. During the same time, there is a phenomenon of internal friction between sand particles caused by the inadequate wrapping of clay particles. Combined with the results of scanning electron microscopy and optical microscopy, the appearance of these phenomena and the transition process of the structure of the mixture from the clay structure to the sand structure were confirmed.