Meso-scale Modeling of the Drilling of Carbon Fibre Reinforced Plastic: Geometry and Numerical Analysis

This paper discussed the 3D finite element modeling (FEM) of the drilling of uni-directional Carbon Fibre Reinforced Plastic (CFRP). Most of the real life parts of CFRP are modeled with single layer shell element and can be modeled as composite by assigning a composite property to it. A Meso-Scale (Laminate Level) approach has been developed to extract displacements, overall stiffness behavior, and detailed stresses and strains. The objective of this study is to implement a ply-based modeling technology to model the laminates and to analyze the interaction mechanisms between the drilling tool and material to validate if the meso-scale approach would be the ideal solution to characterize the drilling induced damage. Results show the model has proved its ability to correctly estimate the thrust force and torque

The manufacturing and the application of polycrystalline diamond tools – A comprehensive review

Advanced materials such as titanium alloys and metal matrix composites are extensively used in the aerospace industry and biomedical engineering. They are difficult to machine because of the severe abrasion and high temperature at the tool/chip and tool/workpiece interfaces which cause severe tool wear and premature tool rejection. Compared with conventional cutting tools, polycrystalline diamond (PCD) tools are promising in machining refractory metals and hard-to-machine materials because of the outstanding mechanical properties of PCD. This paper reviewed the manufacturing and application of PCD cutting tools. The researches on manufacturing process of PCD tools and the application in cutting hard-to-machine materials were analysed, and the results and findings were comprehensively discussed. Two most widely used refining methods including abrasive grinding and electrical discharge grinding (EDG) as well as the defects caused by the processes were presented. The wear process of PCD tools in different industrial cutting methods and the wear mechanism of different PCD materials were explained in both micro-scale and macro-scale. Research directions and the trend of the application of PCD cutting tools were introduced

México: informe de la coyuntura económica: primer trimestre de 1999

Incluye Bibliografí

Mesenchymal stem cells as carriers and amplifiers in CRAd delivery to tumors

<p>Abstract</p> <p>Background</p> <p>Mesenchymal stem cells (MSCs) have been considered to be the attractive vehicles for delivering therapeutic agents toward various tumor diseases. This study was to explore the distribution pattern, kinetic delivery of adenovirus, and therapeutic efficacy of the MSC loading of E1A mutant conditionally replicative adenovirus Adv-Stat3(-) which selectively replicated and expressed high levels of anti-sense Stat3 complementary DNA in breast cancer and melanoma cells.</p> <p>Methods</p> <p>We assessed the release ability of conditionally replicative adenovirus (CRAd) from MSC using crystal violet staining, TCID₅₀assay, and quantitative PCR. In vitro killing competence of MSCs carrying Adv-Stat3(-) toward breast cancer and melanoma was performed using co-culture system of transwell plates. We examined tumor tropism of MSC by Prussian blue staining and immunofluorescence. In vivo killing competence of MSCs carrying Adv-Stat3(-) toward breast tumor was analyzed by comparison of tumor volumes and survival periods.</p> <p>Results</p> <p>Adv-Stat3(-) amplified in MSCs and were released 4 days after infection. MSCs carrying Adv-Stat3(-) caused viral amplification, depletion of Stat3 and its downstream proteins, and led to significant apoptosis in breast cancer and melanoma cell lines. In vivo experiments confirmed the preferential localization of MSCs in the tumor periphery 24 hours after tail vein injection, and this localization was mainly detected in the tumor parenchyma after 72 hours. Intravenous injection of MSCs carrying Adv-Stat3(-) suppressed the Stat3 pathway, down-regulated Ki67 expression, and recruited CD11b-positive cells in the local tumor, inhibiting tumor growth and increasing the survival of tumor-bearing mice.</p> <p>Conclusions</p> <p>These results indicate that MSCs migrate to the tumor site in a time-dependent manner and could be an effective platform for the targeted delivery of CRAd and the amplification of tumor killing effects.</p

Comparative Analysis of mRNA Isoform Expression in Cardiac Hypertrophy and Development Reveals Multiple Post-Transcriptional Regulatory Modules

Cardiac hypertrophy is enlargement of the heart in response to physiological or pathological stimuli, chiefly involving growth of myocytes in size rather than in number. Previous studies have shown that the expression pattern of a group of genes in hypertrophied heart induced by pressure overload resembles that at the embryonic stage of heart development, a phenomenon known as activation of the “fetal gene program”. Here, using a genome-wide approach we systematically defined genes and pathways regulated in short- and long-term cardiac hypertrophy conditions using mice with transverse aortic constriction (TAC), and compared them with those regulated at different stages of embryonic and postnatal development. In addition, exon-level analysis revealed widespread mRNA isoform changes during cardiac hypertrophy resulting from alternative usage of terminal or internal exons, some of which are also developmentally regulated and may be attributable to decreased expression of Fox-1 protein in cardiac hypertrophy. Genes with functions in certain pathways, such as cell adhesion and cell morphology, are more likely to be regulated by alternative splicing. Moreover, we found 3′UTRs of mRNAs were generally shortened through alternative cleavage and polyadenylation in hypertrophy, and microRNA target genes were generally de-repressed, suggesting coordinated mechanisms to increase mRNA stability and protein production during hypertrophy. Taken together, our results comprehensively delineated gene and mRNA isoform regulation events in cardiac hypertrophy and revealed their relations to those in development, and suggested that modulation of mRNA isoform expression plays an importance role in heart remodeling under pressure overload

Two new species of the genus Xanthochlorus from China (Diptera, Dolichopodidae, Xanthochlorinae)

Volume: 750Start Page: 141End Page: 14

Two new species of the genus Xanthochlorus from China (Diptera, Dolichopodidae, Xanthochlorinae)

The subfamily Xanthochlorinae comprises a single genus Xanthochlorus, and is rare in collections. Previously, there were four known species in the genus Xanthochlorus from China. In this paper, the species of the Xanthochlorus from China are reviewed. The following two species from Gansu Province of China are described as new to science: Xanthochlorus gansuensis sp. n. and Xanthochlorus tewoensis sp. n. A key to species of the Xanthochlorus from China is provided

Efficiency Evaluation and Selection Strategies for Green Portfolios under Different Risk Appetites

Since investors have diverse risk motives for green investments, this paper uses data envelopment analysis (DEA) and simulation to accurately evaluate the efficiency of green portfolios from the perspective of investors’ subjective risks and accordingly provide suitable investment selection strategies. On the one hand, the paper integrates investors’ risk preferences with efficiency evaluation models under the framework of behavioral finance, and then constructs a green portfolio efficiency evaluation model based on cumulative prospect theory on the basis of defining green portfolio efficiency. On the other hand, by bringing realistic Chinese stock data into the evaluation model and solving it with the help of large number iteration and DEA, the trends of frontier movements and selection options of green portfolios under the influence of different risk preferences are obtained and analyzed. The empirical simulation reveals that: (1) if investors’ risk aversion at return rises, it will not only reduce the expected prospective value of the green portfolio, but also shift down and flatten the frontier of the green portfolio; indicating that investors will tend to reduce their risk-tolerant attitude and prefer a conservative strategy under the same value condition. (2) If investors increase their risk-seeking in the case of losses, this will raise the expected prospect value of the green portfolio and lead to an inward and steeper green portfolio frontier; suggesting that, given equal value, investors prefer to increase their risk-taking capacity and use aggressive strategies in the hope of turning the profit around. (3) The efficiency results of green portfolios are very sensitive to changes in investors’ risk preferences, suggesting that investors need to select and match green portfolios with their own risk appetite levels. The above findings enrich and expand the risk types and evaluation models in previous green investment studies from the perspective of investors’ subjective risk