222 research outputs found

    Microstructure refinement by tool rotation-induced vibration in incremental sheet forming

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    This paper presents a study of employing tool rotation-induced vibrations in incremental sheet forming (V-ISF) to produce sheet metal parts with laminated ultrafine-grained structures. Non-axisymmetric tools were developed to generate tool vibration and surface shear deformation of sheet material during forming. Using the V-ISF process, magnesium sheets of AZ31 were formed to the hyperbolic cones and laminated ultrafine grains with higher micro hardness were obtained by tool generated low frequency vibrations with large amplitudes. To further investigate surface shear deformation induced during processing, the hole-deformation analysis of samples cut from the formed hyperbolic cones was performed. This study found that large surface shear deformation of the sheet and the tool vibration during incremental forming are the two key factors for the formation of laminated ultrafine grains. The developed V-ISF process has a great potential to produce sheet metal parts with refined grains and greater micro hardness

    Ganoderma lucidum polysaccharides in human monocytic leukemia cells: from gene expression to network construction

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    <p>Abstract</p> <p>Background</p> <p><it>Ganoderma lucidum </it>has been widely used as a herbal medicine for promoting health and longevity in China and other Asian countries. Polysaccharide extracts from <it>Ganoderma lucidum </it>have been reported to exhibit immuno-modulating and anti-tumor activities. In previous studies, F3, the active component of the polysaccharide extract, was found to activate various cytokines such as IL-1, IL-6, IL-12, and TNF-<it>Ī±</it>. This gave rise to our investigation on how F3 stimulates immuno-modulating or anti-tumor effects in human leukemia THP-1 cells.</p> <p>Results</p> <p>Here, we integrated time-course DNA microarray analysis, quantitative PCR assays, and bioinformatics methods to study the F3-induced effects in THP-1 cells. Significantly disturbed pathways induced by F3 were identified with statistical analysis on microarray data. The apoptosis induction through the DR3 and DR4/5 death receptors was found to be one of the most significant pathways and play a key role in THP-1 cells after F3 treatment. Based on time-course gene expression measurements of the identified pathway, we reconstructed a plausible regulatory network of the involved genes using reverse-engineering computational approach.</p> <p>Conclusion</p> <p>Our results showed that F3 may induce death receptor ligands to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades.</p

    Estrogen receptor Ī± (ERĪ±) mediates 17Ī²-estradiol (E2)-activated expression of HBO1

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    BACKGROUND: HBO1 (histone acetyltransferase binding to ORC1) is a histone acetyltransferase (HAT) which could exert oncogenic function in breast cancer. However, the biological role and underlying mechanism of HBO1 in breast cancer remains largely unknown. In the current study, we aimed to investigate the role of HBO1 in breast cancer and uncover the underlying molecular mechanism. METHODS: Immunohistochemistry was applied to detect HBO1 protein expression in breast cancer specimens (n = 112). The expression of protein level was scored by integral optical density (IOD) for further statistical analyses using SPSS. Real-time PCR was used to simultaneously measure mRNA levels of HBO1. The HBO1 protein expression in breast cancer cells was confirmed by western blot. RESULTS: HBO1 was highly expressed in breast cancer tissues and significantly correlated with estrogen receptor Ī± (ERĪ±) (p < 0.001) and progestational hormone (PR) (p = 0.002). HBO1 protein level also correlated positively with histology grade in ERĪ± positive tumors (p = 0.016) rather than ERĪ± negative tumors. 17Ī²-estradiol (E2) could upregulate HBO1 gene expression which was significantly inhibited by ICI 182,780 or ERĪ± RNAi. E2-increased HBO1 protein expression was significantly suppressed by treatment with inhibitor of MEK1/2 (U0126) in T47 D and MCF-7 cells. CONCLUSIONS: HBO1 was an important downstream molecule of ERĪ±, and ERK1/2 signaling pathway may involved in the expression of HBO1 increased by E2

    Maternal exposure to ambient air pollution and congenital heart defects in China

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    Background: Evidence of maternal exposure to ambient air pollution on congenital heart defects (CHD) has been mixed and are still relatively limited in developing countries. We aimed to investigate the association between maternal exposure to air pollution and CHD in China.Method: This longitudinal, population-based, case-control study consecutively recruited fetuses with CHD and healthy volunteers from 21 cities, Southern China, between January 2006 and December 2016. Residential address at delivery was linked to random forests models to estimate maternal exposure to particulate matter with an aerodynamic diameter of ā‰¤1 Āµm (PM1), ā‰¤2.5 Āµm, and ā‰¤10 Āµm as well as nitrogen dioxides, in three trimesters. The CHD cases were evaluated by obstetrician, pediatrician, or cardiologist, and confirmed by cardia ultrasound. The CHD subtypes were coded using the International Classification Diseases. Adjusted logistic regression models were used to assess the associations between air pollutants and CHD and its subtypes.Results: A total of 7055 isolated CHD and 6423 controls were included in the current analysis. Maternal air pollution exposures were consistently higher among cases than those among controls. Logistic regression analyses showed that maternal exposure to all air pollutants during the first trimester was associated with an increased odds of CHD (e.g., an interquartile range [13.3 Āµg/m3] increase in PM1 was associated with 1.09-fold ([95% confidence interval, 1.01-1.18]) greater odds of CHD). No significant associations were observed for maternal air pollution exposures during the second trimester and the third trimester. The pattern of the associations between air pollutants and different CHD subtypes was mixed.Conclusions: Maternal exposure to greater levels of air pollutants during the pregnancy, especially the first trimester, is associated with higher odds of CHD in offspring. Further longitudinal well-designed studies are warranted to confirm our findings

    Anapole mediated giant photothermal nonlinearity in nanostructured silicon

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    Featured with a plethora of electric and magnetic Mie resonances, high index dielectric nanostructures offer a versatile platform to concentrate light-matter interactions at the nanoscale. By integrating unique features of far-field scattering control and near-field concentration from radiationless anapole states, here, we demonstrate a giant photothermal nonlinearity in single subwavelength-sized silicon nanodisks. The nanoscale energy concentration and consequent near-field enhancements mediated by the anapole mode yield a reversible nonlinear scattering with a large modulation depth and a broad dynamic range, unveiling a record-high nonlinear index change up to 0.5 at mild incident light intensities on the order of MW/cm2. The observed photothermal nonlinearity showcases three orders of magnitude enhancement compared with that of unstructured bulk silicon, as well as nearly one order of magnitude higher than that through the radiative electric dipolar mode. Such nonlinear scattering can empower distinctive point spread functions in confocal reflectance imaging, offering the potential for far-field localization of nanostructured Si with an accuracy approaching 40 nm. Our findings shed new light on active silicon photonics based on optical anapoles

    Flow characteristics and intrinsic workability of IN718 superalloy

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    This study focuses on deformation characteristics of superalloy IN718 by formulation of a new flowstress model and detailed evaluation of intrinsic workability through the generation of three-dimensional (3D) processing maps with the support of optical microstructural observations. Based on thermomechanical simulation tests using a Gleeble-1500 machine, the flow stress model for superalloy IN718 was built and the flow stress throughout the entire deformation process was described by a peak stress only depending on Zenerā€“Hollomon parameter and strain. The developed model exhibited the strain softening due to dynamic recrystallization (DRX). The intrinsic workability was further investigated by constructing 3D processing maps. The 3D processing maps described the variations of the efficiency of power dissipation and flow instability domains as a function of strain rate, temperature and strain, from which the favourite deformation conditions for thermomechanical processing of IN718 can be established
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