Bioinformatics research in the Asia Pacific: a 2007 update

We provide a 2007 update on the bioinformatics research in the Asia-Pacific from the Asia Pacific Bioinformatics Network (APBioNet), Asia's oldest bioinformatics organisation set up in 1998. From 2002, APBioNet has organized the first International Conference on Bioinformatics (InCoB) bringing together scientists working in the field of bioinformatics in the region. This year, the InCoB2007 Conference was organized as the 6th annual conference of the Asia-Pacific Bioinformatics Network, on Aug. 27–30, 2007 at Hong Kong, following a series of successful events in Bangkok (Thailand), Penang (Malaysia), Auckland (New Zealand), Busan (South Korea) and New Delhi (India). Besides a scientific meeting at Hong Kong, satellite events organized are a pre-conference training workshop at Hanoi, Vietnam and a post-conference workshop at Nansha, China. This Introduction provides a brief overview of the peer-reviewed manuscripts accepted for publication in this Supplement. We have organized the papers into thematic areas, highlighting the growing contribution of research excellence from this region, to global bioinformatics endeavours

A model of the PI cycle reveals the regulating roles of lipid-binding proteins and pitfalls of using mosaic biological data

The phosphatidylinositol (PI) cycle is central to eukaryotic cell signaling. Its complexity, due to the number of reactions and lipid and inositol phosphate intermediates involved makes it difficult to analyze experimentally. Computational modelling approaches are seen as a way forward to elucidate complex biological regulatory mechanisms when this cannot be achieved solely through experimental approaches. Whilst mathematical modelling is well established in informing biological systems, many models are often informed by data sourced from multiple unrelated cell types (mosaic data) or from purified enzyme data. In this work, we develop a model of the PI cycle informed by experimental and omics data taken from a single cell type, namely platelets. We were able to make a number of predictions regarding the regulation of PI cycle enzymes, the importance of the number of receptors required for successful GPCR signaling and the importance of lipid- and protein-binding proteins in regulating second messenger outputs. We then consider how pathway behavior differs, when fully informed by data for HeLa cells and show that model predictions remain consistent. However, when informed by mosaic experimental data model predictions greatly vary illustrating the risks of using mosaic datasets from unrelated cell types

Evaluation of electrochemical impedance and biocorrosion characteristics of as-cast and T4 heat treated AZ91 Mg-alloys in Ringer's solution

The present study aims at understanding the electrochemical impedance and biocorrosion characteristics of AZ91 Mg-alloy in Ringer's solution. As-cast AZ91 Mg-alloy was subjected to T4 heat treatment in a way to homogenize its microstructure by dissolving most of the beta-Mg17Al12 phase at the vicinity of grain boundaries. The electrochemical impedance and biocorrosion performances of these two different microstructures (as-cast and T4 heat treated AZ91 Mg-alloys) in Ringer solution were evaluated by electrochemical impendence spectroscopy, potentiodynamic polarization and weight loss method. EIS spectra showed that both microstructures exhibit similar dynamic response as a function of the immersion time; however, the value of impedance and maximum phase angle are about 50% higher in as-cast AZ91 Mg-alloy as compared to that of homogenized AZ91 Mg-alloy. Weight loss measurement indicated that corrosion resistance of as-cast AZ91 was significantly better than that of homogenized AZ91. Microstructural and XRD analysis revealed that as-cast AZ91 contains a passive film of MgCO3 and CaCO3 precipitates with near spherical morphologies, whereas homogenized AZ91 comprised mainly unstable Mg(OH)(2) film featured by irregular plate-like morphologies. (C) 2019 Published by Elsevier B.V. on behalf of Chongqing University

Correlation between microstructure and wear behavior of AZX915 Mg-alloy reinforced with 12 wt% TiC particles by stir-casting process

The present work concerns with correlation between microstructure and wear behavior of AZX915 Mg-alloy reinforced with 12 wt% of TiC particles by stir-casting process. Dry sliding tests were performed under ambient environment by using a pin-on-disc (EN8 steel) configuration with a normal load of 50 N at a constant sliding speed of 2.50 ms−1. While as-cast composite experienced delamination wear, heat treated composite suffered from delamination and oxidation wear during dry sliding contact. Moreover, the heat treated composite exhibited lower friction and higher wear rate as compared to the as-cast composite. Friction and wear behavior were correlated with microstructures based on the concept of oxidation tendency and crack nucleation/propagation. Further, a schematic model has been proposed illustrating wear mechanisms from the point of view of subsurface microstructural evolution of the AZX915-TiCp composite

Deformation mechanisms and texture evolution of in-situ magnesium matrix composites containing polymer derived SiCNO dispersoids during hot compression

In-situ magnesium matrix composite was fabricated by injecting a liquid polymer directly into, and having it converted into 2.5 vol% SiCNO ceramic dispersoids, within molten Mg using a stir-casting method. The deformation mechanisms and texture evolution for these as-cast composites were investigated in a strain rate range of 10(-3) - 1 s(-1) within a temperature range of 150-350 degrees C under uniaxial compression. It was observed that the deformed composites follow a power-law creep having a stress exponent, n = 8 and activation energy, Q = 149 kJ mol(-1) which suggest that deformation mechanism is controlled by lattice self-diffusion for constant structure creep. It was found that in the range of 150-250 degrees C, with a ratio of rate of work-softening to rate of work-hardening of about 0.80, twinning induced shear bands nucleate and propagate along the direction of maximum shear stress. When the temperature approaches 350 degrees C, the plastic flow is dominated by dislocation assisted slip. Analysis of Zener-Hollomon parameter (Z) revealed that the transition from twinning into dislocation slip dominated deformation progresses at 10(13) s(-1) < Z < 10(13) s(-1). Macro-textural studies confirm that while basal plane assists deformation by twinning mechanism, the non-basal prismatic planes favor significant plastic deformation by dislocation assisted slip for the in-situ composites

Microstructural evolution of die-cast and homogenized AZ91 Mg-alloys during dry sliding condition

Microstructural evolution of die-cast and homogenized AZ91 Mg-alloys was investigated during dry sliding wear condition. Tribological tests were performed using a pin-on-disc (EN8 steel) configuration with a normal load of 50 N at a constant sliding speed of 2.5 ms−1 under ambient environment. Delamination was recognized as a predominant wear mechanism in both of these materials. The die-cast AZ91 Mg-alloy exhibits lower coefficient of friction and higher wear rate. This can be ascribed to increase in the intensity of load bearing capacity of hard β-Mg17Al12 phase, and crack formation/de-cohesion at the interface between primary α-Mg and discontinuous β-Mg17Al12 phases. On the contrary, the homogenized AZ91 Mg-alloy experiences higher coefficient of friction and lower wear rate. The friction-induced microstructural evolution (supersaturated α-Mg to eutectic (α + β-Mg17Al12)) tending to minimize the wear rate by providing barrier to material removal in the near surface region of homogenized AZ91 Mg-alloy. Therefore, experimental observation revealed that an inverse relationship exists between wear rate and coefficient of friction for the investigated materials. The analysis of worn surfaces and subsurfaces by electron microscopy provided evidence to delamination wear and microstructural evolution. Keywords: Mg-alloys, Heat treatment, Microstructural evolution, Wear rate, Delamination, Subsurfac

Effect of melt temperature on microstructural and strength properties of in-situ aluminum metal matrix composites containing SiCNO particles

Polymer Injection Pyrolysis (PIPs) can be adopted to synthesize in-situ ceramic particles within molten metal by stir-casting process. This paper investigated the effect of pyrolysis temperatures on microstructural and strength properties of in-situ aluminum matrix composites containing 2.5 vol% of SiCNO particles. In-situ composites were synthesized by stir-mixing of cross-linked polysilazane at four different pyrolysis temperatures (675–850°C) at which in-situ pyrolysis occurred and then followed by ultrasonic agitation and squeeze casting process. Microstructural data reveals that grain size and the particle size of SiCNO particles decreases with increasing the temperature of the melt at which polymer was introduced into the melt. The increase in the strength properties of the fabricated composites as compared to pure aluminum is almost 210% for the composites fabricated at 850°C while it is marginally 17% for the composites fabricated at 720°C. Fractography studies suggest that composite fabricated at 675°C exhibits a better combination of yield strength and ductility