Effects of nondensifying inclusions on the densification and microstructure of zinc oxide matrix composites

The densification and microstructure development of ZnO containing Zn₇Sb₂O₁₂, ZrO₂, and aggregated ZnO were investigated to elucidate the effect of nondensifying inclusions on the sintering of ceramic/ceramic composites. The inclusion retarded the densification, and the degree of retardation was found to depend on the chemical species of inclusion; Zn₇Sb₂O₁₂ had the largest effect, followed by ZrO₂ and then aggregated ZnO last. The experimental results for aggregated ZnO was explained by the theory which predicts the generation of backstresses. The backstresses give a less significant effect on the densification. For Zn₇Sb₂O₁₂ and ZrO₂, the microstructure of the matrix varied with distance from an inclusion particle; much porosity was observed in the region surrounding the inclusion. Circumferential voids, which are responsible for the suppression of densification, form during the initial stage of sintering. Inclusion particles generate an anchoring effect which retards the densification of the matrix immediately surrounding the inclusion particle during the intermediate stage.Supported by the Inamori Foundation.     

Finite element analysis of the transient motion of stratified viscous fluids under gravity

The present paper deals with the finite element analysis of two-dimensional two-layer density flows in a gravitational field. A fluid in each layer is replaced with a large number of discrete particles, and the motion and deformation of each layer is represented by moving those particles in a Lagrangian manner. The velocity distribution in the whole fluid region is given as the finite element solution of the Navier-Stokes equations and the equation of continuity. In the finite element calculation, free-slip conditions are used on solid wall boundaries because no-slip conditions may cause sticking of some particles to walls. Then, a new technique for the implementation of free-slip conditions on arbitrary curved boundaries is presented. As numerical examples, density flows in a rectangular closed container and Rayleigh-Taylor instability in the container with a circular cross-section have been computed.     

Wood adhesives based on tannin extracts from barks of some pine and spruce species

Barks available in commercial quantities in Australia and overseas have been examined for their efficacy as raw materials for conversion to high quality adhesives for reconstituted wood products. Previously bark from maturePinus radiata was found to be suitable. This paper examines the suitability of barks from four mature pine species (Pinus caribaea, Pinus elliottii, Pinus pinaster andPinus sylvestris), one young pine species (Pinus radiata) and one spruce species (Picea abies). Only the bark extracts ofPinus caribaea andPinus pinaster gave high quality (Type A bond, WBP) wood adhesives. The gluing properties of the adhesives derived from the extracts appeared to be dependent on their contents of formaldehyde-reactive polyflavanoids as indicated by their Stiasny values, with a value of 65% being the minimum for producing a high quality adhesive by the methods used.     

Mechanical stretch induces hypertrophic responses in cardiac myocytes of angiotensin II type 1a receptor knockout mice

Many lines of evidence have suggested that angiotensin II (AngII) plays an important role in the development of cardiac hypertrophy through AngII type 1 receptor (AT1). To determine whether AngII is indispensable for the development of mechanical stress-induced cardiac hypertrophy, we examined the activity of mitogen-activated protein kinase (MAPK) family and the expression of the c-fos gene as hypertrophic responses after stretching cultured cardiac myocytes of AT1a knockout (KO) mice. When cardiac myocytes were stretched by 20% for 10 min, extracellular signal-regulated protein kinases (ERKs) were strongly activated in KO cardiomyocytes as well as wild type (WT) myocytes. Both basal and stimulated levels of ERKs were higher in cardiomyocytes of KO mice than in those of WT mice. Activation of another member of the MAPK family, p38(MAPK), and expression of the c-fos gene were also induced by stretching cardiac myocytes of both types of mice. An AT1 antagonist attenuated stretch-induced activation of ERKs in WT cardiomyocytes but not in KO cardiomyocytes. Down-regulation of protein kinase C inhibited stretch-induced ERK activation in WT cardiomyocytes, whereas a broad spectrum tyrosine kinase inhibitor (genistein) and selective inhibitors of epidermal growth factor receptor (tyrphostin, AG1478, and B42) suppressed stretch-induced activation of ERKs in KO cardiac myocytes. Epidermal growth factor receptor was phosphorylated at tyrosine residues by stretching cardiac myocytes of KO mice. These results suggest that mechanical stretch could evoke hypertrophic responses in cardiac myocytes that lack the AT1 signaling pathway possibly through tyrosine kinase activation.     

Formation of Porous SiC Ceramics by Pyrolysis of Wood Impregnated with Silica

Biomorphous β-SiC ceramics were produced at 1400°C from pine wood impregnated with silica. This one-step carbothermal reduction process decreases the cost of manufacturing of SiC ceramics compared with siliconization of carbonized wood in silicon vapor. The synthesized sample exhibits a 14 m²/g surface area and has a hybrid pore structure with large 5–20 μm tubular macropores and small (<50 nm) slit-shaped mesopores. SiC whiskers of 20–400 nm in diameter and 5–20 μm in length formed within the tubular pores. These whiskers are expected to improve the filtration by removing dust particles that could otherwise penetrate through large pores. After ultrasonic milling, the powdered sample showed an average particle size of ∼30 nm. The SiC nanopowder produced in this process may be used for manufacturing SiC ceramics for structural, tribological, and other applications.     

Materials for supercapacitors: When Li-ion battery power is not enough

Supercapacitors, also known as electrochemical capacitors, have witnessed a fast evolution in the recent years, but challenges remain. This review covers the fundamentals and state-of-the-art developments of supercapacitors. Conventional and novel electrode materials, including high surface area porous carbons for electrical double layer capacitors (EDLCs) and transition metal oxides, carbides, nitrides and their various nanocomposites for pseudocapacitors – are described. Latest characterization techniques help to better understand the charge storage mechanisms in such supercapacitors and recognize their current limitations, while recently proposed synthesis approaches enable various breakthroughs in this field.     

A novel interferon regulatory factor family transcription factor, ICSAT/Pip/LSIRF, that negatively regulates the activity of interferon-regulated genes

We have isolated a novel cDNA clone encoding interferon (IFN) consensus sequence-binding protein in adult T-cell leukemia cell line or activated T cells (ICSAT); this protein is the human homolog of the recently cloned Pip/LSIRF. ICSAT is structurally most closely related to the previously cloned ICSBP, a member of the IFN regulatory factor (IRF) family of proteins that binds to interferon consensus sequences (ICSs) found in many promoters of the IFN-regulated genes. Among T-cell lines investigated, ICSAT was abundantly expressed in human T-cell leukemia virus type 1 (HTLV-1)-infected T cells. When the HTLV-1 tax gene was expressed or phorbol myristake acetate-A23187 stimulation was used, ICSAT expression was induced in Jurkat cells which otherwise do not express ICSAT. When the binding of ICSAT to four different ICSs was tested, the relative differences in binding affinities for those ICSs were determined. To study the functional role of ICSAT, we performed cotransfection experiments with the human embryonal carcinoma cell line N-Tera2. ICSAT was demonstrated to possess repressive function over the gene activation induced by IFN stimulation or by IRF-1 cotransfection. Such repressive function is similar to that seen in IRF-2 or ICSBP. However, we have found that ICSAT has a different repressive effect from that of IRF-2 or ICSBP in some IFN-responsive reporter constructs. These results suggest that a novel mechanism of gene regulation by "differential repression" is used by multiple members of repressor proteins with different repressive effects on the IFN-responsive genes.     

A cubic ordered, mesoporous carbide-derived carbon for gas and energy storage applications

A hierarchical and highly porous carbide-derived carbon (CDC) was obtained by nanocasting of pre-ceramic precursors into cubic ordered silica (KIT-6) and subsequent chlorination. Resulting CDC replica materials show high methane and n-butane uptake and excellent performance as electrode materials in supercapacitors.