Epoxy/triazine based high performance molding compound for next generation power electronics packaging

The power electronics industry has been actively seeking encapsulant materials that can serve in harsher environments. For example, with the power semiconductors leading into SiC era, the higher operation temperature (250 ºC) have proposed great challenges on the packaging materials especially on epoxy molding compound (EMC) technologies, since the temperature exceeds the stability limit of typical epoxy (EP) chemistry. In this thesis, EP/triazine system was selected to develop high temperature stable resin system that can meet the temperature requirement of next generation power electronics packaging. In the first part of the thesis, different approaches were discussed to enhance the high temperature performance of a previously studied cyanate ester (CE)/ biphenyl EP blend which is impaired by the hydrolysis degradation of remaining cyanate groups. Firstly, the effects of different metal catalyst on the CE properties were discussed. Secondly, a triazine containing molecule triglycidyl isocyanurate (TGIC) was employed to increase the triazine content without increasing CE feed ratio to circumstance problem of unreacted cyanate groups. Finally, the high heat resistant novolac type CE was employed to form the NCE/EP blend, and their blends with different feed ratio were systematically evaluated. In the second part, a detailed characterization of a high heat resistant CE/novolac type EP blends and the investigation on their degradation under long-term high temperature storage were summarized. The effects of the CE concentration on the thermomechanical properties of the copolymer were explored, where a tradeoff behavior between the triazine content and crosslink density was accounted for the property change. In addition, the distinguished thermal degradation mechanisms in copolymer with different compositions were identified and illustrated. The knowledge obtained in this work can serve as a reference in the future to formulate EP/triazine based resin system for high temperature applications.M.S

Oridonin Up-regulates Expression of P21 and Induces Autophagy and Apoptosis in Human Prostate Cancer Cells

Background: Oridonin (ORI) could inhibit the proliferation and induce apoptosis in various cancer cell lines. However, the mechanism is not fully understood

Economic policy uncertainty, financial markets and probability of US recessions

AbstractWe use probit recession forecasting models to assess the ability of economic policy uncertainty indexes developed by Baker et al. (2013) to predict future US recessions. The model specifications include policy indexes on their own, and in combination with financial variables, such as interest rate spreads, stock returns and stock market volatility. Both in-sample and out-of-sample analysis suggests that the policy uncertainty indexes are statistically and economically significant in forecasting recessions at the horizons beyond five quarters. The index based on newspaper reports emerges as the best predictor, outperforming the term spread at the longer forecast horizons

Free gas accumulations in basal shear zones of mass-transport deposits (Pearl River Mouth Basin, South China Sea): An important geohazard on continental slope basins

Free gas is an important trigger of instability on continental slopes, and resulting mass-wasting strata can potentially form competent seals to hydrocarbon accumulations. This work uses two high-quality 3D seismic volumes to investigate fluid accumulations at the base of mass-transport deposits in the Pearl River Mouth Basin, South China Sea. In parallel, IODP/ODP borehole data are used to document the petrophysical character of mass-transport deposits formed in similar continental-slope environments to the South China Sea. The interpreted data show gas accumulations as comprising enhanced seismic reflections that are discordant, or vertically stacked, below mass-transport deposits with chaotic seismic facies. Gas was accumulated in basal shear zones of mass-transport deposits in response to differences in capillary pressure and porosity. Free gas in Zone A covers an area of at least 18 km2. In Zone B, the free gas is sub-circular in plan view and covers an area of 30.58 km2 for a volume of sediment approaching 1.5 km3. This work is important as it shows that vertical migration of gas is not significant in mass-transport deposits from the Pearl River Mouth Basin, but up-dip migration along their basal shear zones is suggested in multiple locations. As a result, free gas can pinch-out laterally to extend 1–2 km beyond these same basal shear zones. As a corollary, we show that free gas accumulations below mass-transport deposits comprise an important geohazard and should be taken into account when drilling continental-slope successions in both the South China Sea and continental margins recording important mass wasting. Strata charged with free gas form weak layers, hinting at a novel trigger of retrogressive slope failures on continental slopes worldwide

Single-cell multiomics of the human retina reveals hierarchical transcription factor collaboration in mediating cell type-specific effects of genetic variants on gene regulation

BACKGROUND: Systematic characterization of how genetic variation modulates gene regulation in a cell type-specific context is essential for understanding complex traits. To address this question, we profile gene expression and chromatin accessibility in cells from healthy retinae of 20 human donors through single-cell multiomics and genomic sequencing. RESULTS: We map eQTL, caQTL, allelic-specific expression, and allelic-specific chromatin accessibility in major retinal cell types. By integrating these results, we identify and characterize regulatory elements and genetic variants effective on gene regulation in individual cell types. The majority of identified sc-eQTLs and sc-caQTLs display cell type-specific effects, while the cis-elements containing genetic variants with cell type-specific effects are often accessible in multiple cell types. Furthermore, the transcription factors whose binding sites are perturbed by genetic variants tend to have higher expression levels in the cell types where the variants exert their effects, compared to the cell types where the variants have no impact. We further validate our findings with high-throughput reporter assays. Lastly, we identify the enriched cell types, candidate causal variants and genes, and cell type-specific regulatory mechanism underlying GWAS loci. CONCLUSIONS: Overall, genetic effects on gene regulation are highly context dependent. Our results suggest that cell type-dependent genetic effect is driven by precise modulation of both trans-factor expression and chromatin accessibility of cis-elements. Our findings indicate hierarchical collaboration among transcription factors plays a crucial role in mediating cell type-specific effects of genetic variants on gene regulation

Position and orientation measurement technology for bolter miner body based on dual-screen visual target

Aiming at the problem that it is difficult to achieve the real-time and accurate measurement of the bolter miner’s position and orientation during the excavation process in coal mines, which leads to the difficulty in achieving directional excavation, a guidance method for bolter miner based on dual-screen visual target is proposed. Using two vertically installed light-sensitive imaging screens to form the dual-screen visual target surfaces and the indication laser emitted by the laser instrument presents light spots on the front and rear target surfaces. Combining with the visual measurement, high-precision raster calibration and other technology are applied to establish the mapping relationship of the spot centroid between 2D-3D coordinates, which is used to form the point cloud data of the coordinates. Based on the principle of grid indexing, coordinate transformation and Euler angle solving, combining with the biaxial inclinometer at the bottom of target to obtain the bolter miner body’s real-time position and orientation, the key points’ horizontal/vertical deviations relative to the roadway axis are calculated, which can provide data support for deviation correction during the excavation process. The off-target problem of the system is analyzed by constructing a mathematical model. Meanwhile, the effectiveness of the guidance method is verified by building an experimental platform. The experimental results indicate that this method can achieve a precision measurement of six-degrees-of-freedom spatial pose for the machine body. When the measurement distance is 9 m, the repeatability measurement precision of the yaw angle is better than 0.01º and the error of absolute measurement is less than 0.05º. Within the measurement range of 15−40 m, which uses the total station and mining laser to set the planning line, the measurement errors of key points’ horizontal/vertical deviations are less than 5 mm and 15 mm, respectively. The guiding system developed based on this method has also been successfully applied to the underground roadway excavation in coal mine, which fully meets the requirements of underground roadway excavation and the positioning of the machine body’s key points. The error characteristic of the guiding method is independent of the test distance. Also, all optical measurement functions involved in the method are realized inside the target, which can effectively shield the influence of the underground complex environment for the measurement function, and greatly improve the capacity of anti-dust interference in field application

Immune checkpoint alterations and their blockade in COVID-19 patients

Coronavirus disease 2019 (COVID-19) is a highly contagious disease that seriously affects people’s lives. Immune dysfunction, which is characterized by abnormal expression of multiple immune checkpoint proteins (ICs) on immune cells, is associated with progression and poor prognosis for tumors and chronic infections. Immunotherapy targeting ICs has been well established in modulating immune function and improving clinical outcome for solid tumors and hematological malignancies. The role of ICs in different populations or COVID-19 stages and the impact of IC blockade remains unclear. In this review, we summarized current studies of alterations in ICs in COVID-19 to better understand immune changes and provide strategies for treating COVID-19 patients, particularly those with cancer

Object-Based and Semantic Image Segmentation Using MRF

The problem that the Markov random field (MRF) model captures the structural as well as the stochastic textures for remote sensing image segmentation is considered. As the one-point clique, namely, the external field, reflects the priori knowledge of the relative likelihood of the different region types which is often unknown, one would like to consider only two-pairwise clique in the texture. To this end, the MRF model cannot satisfactorily capture the structural component of the texture. In order to capture the structural texture, in this paper, a reference image is used as the external field. This reference image is obtained by Wold model decomposition which produces a purely random texture image and structural texture image from the original image. The structural component depicts the periodicity and directionality characteristics of the texture, while the former describes the stochastic. Furthermore, in order to achieve a good result of segmentation, such as improving smoothness of the texture edge, the proportion between the external and internal fields should be estimated by regarding it as a parameter of the MRF model. Due to periodicity of the structural texture, a useful by-product is that some long-range interaction is also taken into account. In addition, in order to reduce computation, a modified version of parameter estimation method is presented. Experimental results on remote sensing image demonstrating the performance of the algorithm are presented

Targeting LAG-3, TIM-3, and TIGIT for cancer immunotherapy

Abstract In one decade, immunotherapy based on immune checkpoint blockades (ICBs) has become a new pillar of cancer treatment following surgery, radiation, chemotherapy, and targeted therapies. However, not all cancer patients benefit from single or combination therapy with anti-CTLA-4 and anti-PD-1/PD-L1 monoclonal antibodies. Thus, an increasing number of immune checkpoint proteins (ICPs) have been screened and their effectiveness evaluated in preclinical and clinical trials. Lymphocyte activation gene-3 (LAG-3), T cell immunoglobulin and mucin-domain-containing-3 (TIM-3), and T cell immunoreceptor with immunoglobulin and tyrosine-based inhibitory motif (ITIM) domain (TIGIT) constitute the second wave of immunotherapy targets that show great promise for use in the treatment of solid tumors and leukemia. To promote the research and clinical application of ICBs directed at these targets, we summarize their discovery, immunotherapy mechanism, preclinical efficiency, and clinical trial results in this review