72 research outputs found

    Numerical simulation of mechanical wave propagation during solidification of ZL205A alloy

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    High-precision, large-domain three-dimensional manipulation of nano-materials for fabrication nanodevices

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    Nanoscaled materials are attractive building blocks for hierarchical assembly of functional nanodevices, which exhibit diverse performances and simultaneous functions. We innovatively fabricated semiconductor nano-probes of tapered ZnS nanowires through melting and solidifying by electro-thermal process; and then, as-prepared nano-probes can manipulate nanomaterials including semiconductor/metal nanowires and nanoparticles through sufficiently electrostatic force to the desired location without structurally and functionally damage. With some advantages of high precision and large domain, we can move and position and interconnect individual nanowires for contracting nanodevices. Interestingly, by the manipulating technique, the nanodevice made of three vertically interconnecting nanowires, i.e., diode, was realized and showed an excellent electrical property. This technique may be useful to fabricate electronic devices based on the nanowires' moving, positioning, and interconnecting and may overcome fundamental limitations of conventional mechanical fabrication

    Familial co-aggregation and shared genetics of cardiometabolic disorders and traits:data from the multi-generational Lifelines Cohort Study

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    BACKGROUND: It is unclear to what extent genetics explain the familial clustering and the co-occurrence of distinct cardiometabolic disorders in the general population. We therefore aimed to quantify the familial (co-)aggregation of various cardiometabolic disorders and to estimate the heritability of cardiometabolic traits and their genetic correlations using the large, multi-generational Lifelines Cohort Study.METHODS: We used baseline data of 162,416 participants from Lifelines. Cardiometabolic disorders including type 2 diabetes (T2D), cardiovascular diseases, hypertension, obesity, hypercholesterolemia, and metabolic syndrome (MetS), were defined in adult participants. Fifteen additional cardiometabolic traits indexing obesity, blood pressure, inflammation, glucose regulation, and lipid levels were measured in all included participants. Recurrence risk ratios (λ R) for first-degree relatives (FDR) indexed familial (co-)aggregation of cardiometabolic disorders using modified conditional Cox proportional hazards models and were compared to those of spouses. Heritability (h 2), shared environment, and genetic correlation (r g) were estimated using restricted maximum likelihood variance decomposition methods, adjusted for age, age 2, and sex. RESULTS: Individuals with a first-degree relative with a cardiometabolic disorder had a higher risk of the same disorder, ranging from λ FDR of 1.23 (95% CI 1.20-1.25) for hypertension to λ FDR of 2.48 (95% CI 2.15-2.86) for T2D. Most of these were higher than in spouses (λ Spouses  &lt; λ FDR), except for obesity which was slightly higher in spouses. We found moderate heritability for cardiometabolic traits (from h 2 CRP: 0.26 to h 2 HDL: 0.50). Cardiometabolic disorders showed positive familial co-aggregation, particularly between T2D, MetS, and obesity (from λ FDR obesity-MetS: 1.28 (95% CI 1.24-1.32) to λ FDR MetS-T2D: 1.61 (95% CI 1.52-1.70)), consistent with the genetic correlations between continuous intermediate traits (ranging from r g HDL-Triglycerides: - 0.53 to r g LDL-Apolipoprotein B: 0.94). CONCLUSIONS: There is positive familial (co-)aggregation of cardiometabolic disorder, moderate heritability of intermediate traits, and moderate genetic correlations between traits. These results indicate that shared genetics and common genetic architecture contribute to cardiometabolic disease.</p

    Multi-ancestry genome-wide association study accounting for gene-psychosocial factor interactions identifies novel loci for blood pressure traits

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    Psychological and social factors are known to influence blood pressure (BP) and risk of hypertension and associated cardiovascular diseases. To identify novel BP loci, we carried out genome-wide association meta-analyses of systolic, diastolic, pulse, and mean arterial BP, taking into account the interaction effects of genetic variants with three psychosocial factors: depressive symptoms, anxiety symptoms, and social support. Analyses were performed using a two-stage design in a sample of up to 128,894 adults from five ancestry groups. In the combined meta-analyses of stages 1 and 2, we identified 59 loci (p value &lt; 5e−8), including nine novel BP loci. The novel associations were observed mostly with pulse pressure, with fewer observed with mean arterial pressure. Five novel loci were identified in African ancestry, and all but one showed patterns of interaction with at least one psychosocial factor. Functional annotation of the novel&nbsp;loci supports a major role for genes implicated in the immune response (PLCL2), synaptic function and neurotransmission (LIN7A and PFIA2), as well as genes previously implicated in neuropsychiatric or stress-related disorders (FSTL5 and CHODL). These findings underscore the importance of considering psychological and social factors in gene discovery for BP, especially in non-European populations

    HDB FLATS-EXAMINING THE INVESTMENT POTENTIAL OF PUBLIC HOUSING IN SINGAPORE

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    Bachelor'sBACHELOR OF SCIENCE (REAL ESTATE

    Mechanical Wave Propagation in Solidifying Al-Cu-Mn-Ti Alloy and Its Effect on Solidification Feeding

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    The wave field in solidifying metals is the theoretical basis for analyzing the effects of mechanical vibration on solidification, but there is little research on this topic. This study investigated the wave field and its effect on the solidification feeding in the low-pressure sand casting (LPSC) of Al-Cu-Mn-Ti alloy through experimental and numerical investigation. The solidification temperature field was simulated by AnycastingTM, and the wave field was simulated by the self-developed wave propagation software. The shrinkage defect detection showed that applying vibration had a greater promotional effect on feeding than increasing the holding pressure. The predicted defects under vibration coincided with the detections. The displacement field showed that the casting vibrated harmonically with an inhomogeneous amplitude distribution under the continuous harmonic vibration excitation, and the vibration energy was mainly concentrated in the feeding channel. With solidification, the ux amplitude reduced rapidly after the overlapping of dendrites, finally reducing slowly to a certain level; the uy amplitude reduced dramatically after the occurrence of a quasi-solid phase, finally reducing slowly to near zero. Mechanical vibration produced a severe shear deformation in the quasi-liquid phase&mdash;especially in the lower feeding channel&mdash;reducing the grain size to promote mass feeding. The feeding pressure and feeding gap were changed periodically under vibration, causing the vibration-promoting interdendritic feeding rate to fluctuate and eventually stabilize at about 13.4%. The mechanical vibration can increase the feeding pressure difference and change the blockage structure simultaneously, increasing the formation probability of burst feeding

    Mechanical Wave Propagation in Solidifying Al-Cu-Mn-Ti Alloy and Its Effect on Solidification Feeding

    No full text
    The wave field in solidifying metals is the theoretical basis for analyzing the effects of mechanical vibration on solidification, but there is little research on this topic. This study investigated the wave field and its effect on the solidification feeding in the low-pressure sand casting (LPSC) of Al-Cu-Mn-Ti alloy through experimental and numerical investigation. The solidification temperature field was simulated by AnycastingTM, and the wave field was simulated by the self-developed wave propagation software. The shrinkage defect detection showed that applying vibration had a greater promotional effect on feeding than increasing the holding pressure. The predicted defects under vibration coincided with the detections. The displacement field showed that the casting vibrated harmonically with an inhomogeneous amplitude distribution under the continuous harmonic vibration excitation, and the vibration energy was mainly concentrated in the feeding channel. With solidification, the ux amplitude reduced rapidly after the overlapping of dendrites, finally reducing slowly to a certain level; the uy amplitude reduced dramatically after the occurrence of a quasi-solid phase, finally reducing slowly to near zero. Mechanical vibration produced a severe shear deformation in the quasi-liquid phase—especially in the lower feeding channel—reducing the grain size to promote mass feeding. The feeding pressure and feeding gap were changed periodically under vibration, causing the vibration-promoting interdendritic feeding rate to fluctuate and eventually stabilize at about 13.4%. The mechanical vibration can increase the feeding pressure difference and change the blockage structure simultaneously, increasing the formation probability of burst feeding

    Effect of Mechanical Vibration on the Mechanical Properties and Solidification Feeding in Low-Pressure Sand Casting of Al-Cu-Mn-Ti Alloy

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    The shrinkage defects of Al-Cu-Mn-Ti alloy seriously hinder its application in high-performance engineering. In this study, mechanical vibration was introduced to low-pressure sand casting (LPSC) by a waveguide rod to eliminate shrinkage defects and improve mechanical properties. Four LPSC castings were performed by changing the solidification conditions: 20 kPa solidification pressure without and with 14 Hz vibration and 40 kPa without and with 24 Hz (the natural frequency of a casting system) vibration. The shrinkage defects, microstructures, and mechanical tensile properties at room temperature and at 2 mm/min tensile rate were investigated. X-ray detections showed that applying vibration was more effective than increasing solidification pressure in improving solidification feeding, while the most effective method was applying both simultaneously, which eliminated the shrinkage defects and increased the density by 2.7%. Microstructures exhibited that the average size of primary &alpha;-Al grains were reduced by 29.5%; mechanical tests showed that the ultimate tensile strength and the elongation increased by 21.7% and 7.8%, respectively, by applying vibration and increasing the solidification pressure simultaneously, as compared to the casting with 20 kPa solidification pressure without vibration. Mechanical vibration was conducive to mass feeding by refining the primary grains, to interdendritic feeding by reducing the threshold pressure gradient, and to burst feeding by collapsing the barrier
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