Descriptors of intrinsic hydrodynamic thermal transport: screening a phonon database in a machine learning approach

Machine learning techniques are used to explore the intrinsic origins of the hydrodynamic thermal transport and to find new materials interesting for science and engineering. The hydrodynamic thermal transport is governed intrinsically by the hydrodynamic scale and the thermal conductivity. The correlations between these intrinsic properties and harmonic and anharmonic properties, and a large number of compositional (290) and structural (1224) descriptors of 131 crystal compound materials are obtained, revealing some of the key descriptors that determines the magnitude of the intrinsic hydrodynamic effects, most of them related with the phonon relaxation times. Then, a trained black-box model is applied to screen more than 5000 materials. The results identify materials with potential technological applications. Understanding the properties correlated to hydrodynamic thermal transport can help to find new thermoelectric materials and on the design of new materials to ease the heat dissipation in electronic devices.to ease the heat dissipation in electronic devices.

Decomposition and Nutrient Releasing of Biochar Compound Materials in Soil with Different Textures

Combining biochar with chemical fertilizers or compost not only improves the shortcomings of biochar’s lack of fertility, but also extends the benefits of the compost. The application of biochar composite materials will be a future agricultural management strategy. In this study bagasse compost was mixed with wood biochar (w/w) at rates of 0% (B), 25% (BC), 50% (BC3), and 100% (no biochar, C) to produce four types of particle biochar compound materials (pBCM). These materials were applied to two types of soil (sandy soil and clayey soil) for a 180-day incubation to determine the decomposition rate and the nutrient release efficiency of the pBCMs. The results showed that C treatment had the highest decomposition rate in both types of soil. Overall, the materials decomposed faster in the sandy soil than in the clayey soil. Plants were grown over two 30-day crop periods. The plant yields of treatments C and BC3 were the highest in the first period and respectively decreased and increased in the second period. The experiment results revealed that in the biochar–compost compounds, compost increased the use efficiency of nitrogen and phosphorus in the soil, and biochar increased the nutrient use efficiency in the second period. These compound materials had greater capacity for long-term supply of nutrients in soil than did single-component ones.

Review of Thermoelectric Generators at Low Operating Temperatures: Working Principles and Materials

Thermoelectric generators (TEGs) are a form of energy harvester and eco-friendly power generation system that directly transform thermal energy into electrical energy. The thermoelectric (TE) method of energy harvesting takes advantage of the Seebeck effect, which offers a simple solution for fulfilling the power-supply demand in almost every electronics system. A high-temperature condition is commonly essential in the working mechanism of the TE device, which unfortunately limits the potential implementation of the device. This paper presents an in-depth analysis of TEGs at low operating temperature. The review starts with an extensive description of their fundamental working principles, structure, physical properties, and the figure of merit (ZT). An overview of the associated key challenges in optimising ZT value according to the physical properties is discussed, including the state of the art of the advanced approaches in ZT optimisation. Finally, this manuscript summarises the research status of Bi2Te3-based semiconductors and other compound materials as potential materials for TE generators working at low operating temperatures. The improved TE materials suggest that TE power-generation technology is essential for sustainable power generation at near-room temperature to satisfy the requirement for reliable energy supplies in low-power electrical/electronics systems.

High-Efficiency GaAs-Based Solar Cells

The III-V compound solar cells represented by GaAs solar cells have contributed as space and concentrator solar cells and are important as sub-cells for multi-junction solar cells. This chapter reviews progress in III-V compound single-junction solar cells such as GaAs, InP, AlGaAs and InGaP cells. Especially, GaAs solar cells have shown 29.1% under 1-sun, highest ever reported for single-junction solar cells. In addition, analytical results for non-radiative recombination and resistance losses in III-V compound solar cells are shown by considering fundamentals for major losses in III-V compound materials and solar cells. Because the limiting efficiency of single-junction solar cells is 30-32%, multi-junction junction solar cells have been developed and InGaP/GaAs based 3-junction solar cells are widely used in space. Recently, highest efficiencies of 39.1% under 1-sun and 47.2% under concentration have been demonstrated with 6-junction solar cells. This chapter also reviews progress in III-V compound multi-junction solar cells and key issues for realizing high-efficiency multi-junction cells.

Effect of Epoxy Molding Compound Material and Roughness Leadframe to Integrated Circuit Package for Automotive Devices

This research studied about an effect of epoxy molding compound material and roughness leadframe of integrated circuit package for automotive device. In manufacturing process, the epoxy molding compound material and leadframe roughness are main factors that effect to coefficient of thermal expansion (CTE) and reliability for automotive device package with no delamination in high temperature application. In experiment, two types of epoxy molding compound materials were studied and compared between standard and roughened leadframe for quad flat non lead (QFN) package. For reliability test, the epoxy molding compound materials type A and type B with different leadframe were analyzed with moisture sensitivity level 1 to observe delamination inside packages. The results showed that CTE of epoxy molding compound material type A is less CTE mismatch than that of epoxy molding compound material type B with both standard and roughness leadframe. Moreover, the results also found no delamination for epoxy molding compound material type A with roughened leadframe. In addition, both epoxy molding compound materials showed significant delamination inside packages with standard leadframe.

CLINICAL AND LABORATORY TESTING OF A NEW MODIFICATION OF TWO-LAYER "SILEP" DENTURES USED IN PROSTHETIC DENTISTRY

Dentistry is a part of medicine, where various polymer materials were used for the first time. Many factors forced researchers to find more stable, versatile, and hygienic materials for the manufacture of dental products. It is important to note that the search for the ideal polymer dental material is still ongoing. This is because modern polymers, in some cases, do not meet the specified requirements for chemical, physical, strength, and elastic properties. Based on the data on the method of creating and using silicone material for the base of the removable prosthesis "Gossil", an improved silicone material for two-layer dentures "Silep" was developed, as well as a special primer for better connection of the lining with the rigid acrylic base of the prosthesis. To evaluate the most suitable compound, materials were tested for several parameters, such as tensile strength, elongation, and shore hardness. In addition to selecting a suitable material for modification, the selection and testing of an adhesive that allows the chemical bonding of the acrylate surface to the siloxane surface were carried out.

Clinical and Laboratory Testing of a New Modification of Two-Layer "Silep" Dentures Used in Prosthetic Dentistry

Dentistry is a part of medicine, where various polymer materials were used for the first time. Many factors forced researchers to find more stable, versatile, and hygienic materials for the manufacture of dental products. It is important to note that the search for the ideal polymer dental material is still ongoing. This is because modern polymers, in some cases, do not meet the specified requirements for chemical, physical, strength, and elastic properties. Based on the data on the method of creating and using silicone material for the base of the removable prosthesis "Gossil", an improved silicone material for two-layer dentures "Silep" was developed, as well as a special primer for better connection of the lining with the rigid acrylic base of the prosthesis. To evaluate the most suitable compound, materials were tested for several parameters, such as tensile strength, elongation, and shore hardness. In addition to selecting a suitable material for modification, the selection and testing of an adhesive that allows the chemical bonding of the acrylate surface to the siloxane surface were carried out

Study of the infl uence of plasticizer DES M-2 on the physical, mechanical and technological properties of plasticate PVC

The paper presents the results of studies of the infl uence of the new plasticizer DES M-2 on the physical, mechanical, technological and operational properties of plasticate PVC. The effi ciency of using M-2 DES for PVC plasticization is shown. Practical recommendations are formulated that are necessary when compiling PVC compound materials and products using DES M-2.