40 research outputs found

    Influence of Material Properties on the Fluid-Structure Interaction aspects during Molded Underfill Process

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    This paper presents the investigation of the effects of epoxy moulding compound’ (EMC) viscosity on the FSI aspects during moulded underfill process (MUF). Finite volume (FV) code and finite element (FE) code were connected online through the Mesh-based Parallel Code Coupling Interface (MpCCI) method for fluid and structural analysis. The EMC flow behaviour was modelled by Castro-Macosko model, which was written in C language and incorporated into the FV analysis. Real-time predictions on the flow front, chip deformation and stress concentration were solved by FV- and FE-solver. Increase in EMC viscosity raises the deformation and stress imposed on IC and solder bump, which may induce unintended features on the IC structure. The current simulation is expected to provide the better understandings and clear visualization of FSI in the moulded underfill process

    Trans-ancestry genome-wide association study identifies 12 genetic loci influencing blood pressure and implicates a role for DNA methylation

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    We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 × 10-11 to 5.0 × 10-21). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 × 10-6). Our results provide new evidence for the role of DNA methylation in blood pressure regulation

    The genetic architecture of type 2 diabetes

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    The genetic architecture of common traits, including the number, frequency, and effect sizes of inherited variants that contribute to individual risk, has been long debated. Genome-wide association studies have identified scores of common variants associated with type 2 diabetes, but in aggregate, these explain only a fraction of heritability. To test the hypothesis that lower-frequency variants explain much of the remainder, the GoT2D and T2D-GENES consortia performed whole genome sequencing in 2,657 Europeans with and without diabetes, and exome sequencing in a total of 12,940 subjects from five ancestral groups. To increase statistical power, we expanded sample size via genotyping and imputation in a further 111,548 subjects. Variants associated with type 2 diabetes after sequencing were overwhelmingly common and most fell within regions previously identified by genome-wide association studies. Comprehensive enumeration of sequence variation is necessary to identify functional alleles that provide important clues to disease pathophysiology, but large-scale sequencing does not support a major role for lower-frequency variants in predisposition to type 2 diabetes

    The trans-ancestral genomic architecture of glycemic traits

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    Glycemic traits are used to diagnose and monitor type 2 diabetes and cardiometabolic health. To date, most genetic studies of glycemic traits have focused on individuals of European ancestry. Here we aggregated genome-wide association studies comprising up to 281,416 individuals without diabetes (30% non-European ancestry) for whom fasting glucose, 2-h glucose after an oral glucose challenge, glycated hemoglobin and fasting insulin data were available. Trans-ancestry and single-ancestry meta-analyses identified 242 loci (99 novel; P < 5 x 10(-8)), 80% of which had no significant evidence of between-ancestry heterogeneity. Analyses restricted to individuals of European ancestry with equivalent sample size would have led to 24 fewer new loci. Compared with single-ancestry analyses, equivalent-sized trans-ancestry fine-mapping reduced the number of estimated variants in 99% credible sets by a median of 37.5%. Genomic-feature, gene-expression and gene-set analyses revealed distinct biological signatures for each trait, highlighting different underlying biological pathways. Our results increase our understanding of diabetes pathophysiology by using trans-ancestry studies for improved power and resolution.A trans-ancestry meta-analysis of GWAS of glycemic traits in up to 281,416 individuals identifies 99 novel loci, of which one quarter was found due to the multi-ancestry approach, which also improves fine-mapping of credible variant sets.Diabetes mellitus: pathophysiological changes and therap

    Survey of levels of support or opposition to the FCTC by important constituencies in Malaysia

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    Tobacco industry interference poses a big challenge to tobacco control policy advocates. The objective of the research is to assess the knowledge, opinions and perceptions toward the FCTC among major constituencies, to inform and guide decision making around implementation and enforcement of tobacco control policies in Malaysia. Findings from a survey are presented in terms of awareness of health risks and anti-tobacco campaigns and enforcement. By signing and ratifying the FCTC the Malaysian government has made a commitment to implement its various provisions, but there is evidence that the industry is changing tactics to circumvent FCTC provisions

    Effects of Temperature on the Wave Soldering of Printed Circuit Boards: CFD Modeling Approach

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    ABSTRACT This study investigated the effects of temperature on the wave soldering of printed circuit boards (PCBs) using three-dimensional finite volume analysis. A computational solder pot model consisting of a six-blade rotational propeller was developed and meshed using tetrahedral elements. The leaded molten solder (Sn63Pb37) distribution and PCB wetting profile were determined using the volume of fluid technique in the fluid flow solver, FLUENT. In this study, the effects of five different molten solder temperatures (456 K, 473 K, 523 K, 583 K, and 643 K) on the wave soldering of a 70 mm × 146 mm PCB were considered. The effects of temperature on wetting area, wetting profile, velocity vector, and full wetting time were likewise investigated. Molten solder temperature significantly affected the wetting time and distribution of PCBs. The molten solder temperature at 523 K demonstrated desirable wetting distribution and yielded a stable fountain profile and was therefore considered the best temperature in this study. The simulation results were substantiated by the experimental results
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