Newer synthetic approaches to surfactants, lipids, and related compounds based on C-3 building blocks: Recent advances related to fatty chemistry

Many lipids derived from natural sources are based on the glycerin molecule. Synthetically alkyl glycidyl ether can be used as a C-3 building block for lipid molecules as well as alkyl glyceryl ether. Several glycidyl and glyceryl ethers have been studied as C-3 synthetic building blocks for lipids used in surfactants/emulsifiers, cosmetics, or toiletries. From an environmental viewpoint, several surfactants and detergents have been modified by using epichlorohydrin or glycerides as C-3 building blocks to have higher performance or biodegradability. Recently, complex lipid molecules having special bioactivities have attracted attention among chemists. Glycidyl ether would be expected to be one of the synthetic building blocks for such complex lipids.     

Interaction between lead‐free multicomponent alkali borosilicate glass frits and hematite in red overglaze enamels

Japanese traditional red overglaze enamel decorations on porcelain known as akae are produced using lead‐containing frits, leading to a problem of lead release. Although many lead‐free frits have been developed, a well‐colored akae has not yet been realized, mainly because of no information on the reaction between lead‐free frits and hematite during the heating process in akae production. To reveal the effect of such interaction between the frits and hematite in akae on the color tone, various akae test pieces were prepared and investigated. On using low‐melting‐point lead‐free alkali borosilicate glass system, which contain zinc oxide, the formation of zinc ferrite proceeds simultaneously with the dissolution and particle growth of hematite in the frit melt. The particle growth rate due to dissolution and precipitation in the frit melt is faster than that due to sintering of particles caused by heat treatment of hematite powder in dry process. The dissolving capacity and promoting effect of particle growth depended on frit compositions. We also showed that the composition of akae glass layer varies because of ions diffusing from the glaze layer. Compositional changes in the akae glass could strongly affect the reactivity between the frits and hematite, resulting in variation in the color tone, the crystal phases formed, and their segregated states.     

Chemical reaction between lead-free multicomponent alkali borosilicate glass frit and hematite during heat treatment

A mixture of a lead-free multicomponent alkali borosilicate glass frit containing zinc ions and hematite was heat-treated under various conditions to elucidate the reaction between the two components, which is essentially important for controlling the color of red overglaze enamels. Above the glass transition temperature, the interaction between the frit fluid and hematite was evident, as the viscosity of the frit decreased. Moreover, hematite dissolved, the iron ions diffused into the glass matrix and they precipitated on residual hematite, resulting in enhanced crystal growth through Ostwald ripening. Concurrently, the iron and zinc ions reacted to form zinc ferrite. During cooling, the supersaturated iron ions were consumed for precipitation of hematite and zinc ferrite. Because frit and hematite dramatically react during heat treatment, conventional modification of hematite alone is insufficient. Development of the frit exhibiting low reactivity toward hematite through precise control of physical properties is a future challenging issue.     

Micro-pin Electrodes Formation by Micro-Scanning EDM Process

In recent micro-EDM processes various kinds of thin tool manufacturing methods, including the wire electrical discharge grinding (WEDG) have been proposed to satisfy the growing need for very thin tools. This study describes a new thin tool micro-formation by EDM where a rod electrode is driven through the center of a controlled slit formed between two electrically isolated metal plates to provide a critical path for the rod electrode tool during the process. A micro-pin of the desired shape and diameter is obtained, under stable conditions, in a very short time interval.     

STRESS INTENSITY FACTOR FOR TRANSIENT THERMAL STRESSES IN AN INFINITE ELASTIC BODY WITH AN EXTERNAL CRACK

Abstract

This paper deals with a transient thermal stress problem in an infinite body with an external crack. The elastic medium is cooled by time- and position-dependent temperature on the external crack. It is very difficult to obtain the analytical expression for the temperature, so the finite-difference method is used with respect to a time variable. Thus, the analytical expression for the temperature with respect to the spatial variables may be obtained. The temperature solution reduces to a dual-integral equation for spatial variables by use of the finite-difference method for a time variable. The numerical results for stress intensity factor are obtained.     

COMBINED MACROSCOPIC AND MICROSCOPIC ANALYSIS OF THERMOELASTOPLASTIC STRESSES OF A FUNCTIONALLY GRADED MATERIAL PLATE

This article discusses the elastoplastic thermal stresses induced in a ceramic-metal functionally graded material plate (FGP) subjected to a thermal load taking the fabrication process into consideration. The FGP is divided into three regions. The first region near the cooling, metal, surface of the FGP is produced by ceramic particle-reinforced metal; while the second region near the heat-resistant, ceramic, surface is the opposite; and the third middle region is perfectly mixed by the metal and the ceramic. The first and second regions are governed by the particle-reinforced thermoelastoplastic constitutive equation, while the third region is expressed by the macroscopic analysis. Three cases of the temperature condition are studied: cooling from the fabricated temperature to room temperature, heating from the room temperature, and heating after cooling from the fabricated temperature. The temperature-dependent material properties are considered, and the particle volume fraction is assumed to vary according to a power function along the thickness direction of the FGP. The effect of the distribution parameter of the composition on the macroscopic stress, the stress in the matrix, and the stress in the particle in the FGP are discussed and illustrated in figures. Also, the effect of the fabricated temperature on the maximum tensile matrix stress is discussed.     

TRANSIENT THERMAL STRESS PROBLEM IN A TRANSVERSELY ISOTROPIC FINITE CIRCULAR CYLINDER UNDER THREE-DIMENSIONAL TEMPERATURE FIELD

This paper is concerned with a transient thermal stress problem in a finite circular transversely isotropic solid cylinder subjected to an asymmetrical temperature distribution on a cylindrical surface. The stress fields are found by use of potential functions method. As an example, the temperature and stress fields for a specific case are computed for the sake of comparison to the isotropic body.     

Development of peeling tool for micro-EDM

We propose a simple and fast fabricating method of tool electrode for micro-EDM. A ‘peeling tool’, a wire coated with a different material, has been developed as an interim product for a microelectrode. A zinc layer was coated by electroplating on a tungsten electrode of 100 μm diameter. The zinc layer makes both handling and chucking of the electrode easy. Part of the zinc layer is instantly ‘peeled’ by a single discharge, exposing tungsten electrode under the zinc layer undamaged and the exposed electrode can be used in microhole drilling by EDM. Time-resolved imaging revealed the peeling process dynamically.     

GENERALIZED THERMOELASTICITY IN AN INFINITE SOLID WITH A HOLE

This paper deals with one-dimensional generalized thermoelasticity based on the theories of Lord and Shulman and of Green and Lindsay. A formulation of generalized thermoelasticity that combines both generalized theories is derived. The generalized thermoelastic problems for an infinite solid with a cylindrical hole and an infinite solid with a spherical hole are analyzed by means of the Laplace transform technique. Numerical calculations for temperature, displacement, and stresses under the generalized formulation are carried out and compared with those of classical dynamic coupled theory.     

POTENTIAL FUNCTION METHOD FOR PIEZOTHERMOELASTIC PROBLEMS OF SOLIDS OF CRYSTAL CLASS 6 mm IN CYLINDRICAL COORDINATES

A potential function method for three-dimensional asymmetric problems of piezoiher-moelasticity of hexagonal materials of crystal class 6 mm in cylindrical coordinates is proposed. The method employs two piezothermoelaslic potential functions, four piezoelastic potential functions, and a piezoelectric potential function. One of the piezother-moelastic potentials and the four piezoelastic potential functions are governed by simple uncoupled differential equations, which are derived from the stress equations of equilibrium and the equation of electrostatics. The remaining piezothermoelastic function and the piezoelectric potential function are expressed in terms of the previously obtained piezothermoelastic function. As an illustrative example, the problem of an infinite, thin piezothermoelastic plate subjected to axisymmetric surface heating is analyzed. Numerical results are obtained for the stresses and the electric potential in a cadmium selenide plate. The thermally induced stress distributions are compared with those obtained when the piezo-effect is ignored.