Micromechanics Fatigue Damage Analysis Modeling for Fabric Reinforced Ceramic Matrix Composites

A micromechanics analysis modeling method was developed to analyze the damage progression and fatigue failure of fabric reinforced composite structures, especially for the brittle ceramic matrix material composites. A repeating unit cell concept of fabric reinforced composites was used to represent the global composite structure. The thermal and mechanical properties of the repeating unit cell were considered as the same as those of the global composite structure. The three-phase micromechanics, the shear-lag, and the continuum fracture mechanics models were integrated with a statistical model in the repeating unit cell to predict the progressive damages and fatigue life of the composite structures. The global structure failure was defined as the loss of loading capability of the repeating unit cell, which depends on the stiffness reduction due to material slice failures and nonlinear material properties in the repeating unit cell. The present methodology is demonstrated with the analysis results evaluated through the experimental test performed with carbon fiber reinforced silicon carbide matrix plain weave composite specimens

The Additional Line Component within the Iron K\alpha Profile in MCG-6-30-15: Evidence for Blob Ejection?

The EPIC data of MCG -6-30-15 observed by XMM-Newton were analyzed for the complexities of the iron K-alpha line. Here we report that the additional line component (ALC) at 6.9 keV undoubtedly appears within the broad iron Kalpha; line profile at the high state, whereas it disappears at the low state. These state-dependent behaviors exclude several possible origins and suggest an origin of the ALC in matter being ejected from the vicinity of the black hole. At the low state, the newborn blob ejected from the accretion disk is so Thomson-thick that hard X-rays are blocked from ionizing the old blobs, leading to the disappearance of the ALC. When the blob becomes Thomson-thin as a result of expansion, the hard X-ray will penetrate it and ionize the old ones, emitting the ALC at the high state. The blob ejection is the key to switching the ALC on or off.Comment: 6 pages, 4 Figure

Topological linear magnetoresistivity and thermoconductivity induced by noncentrosymmetric Berry curvature

The Berry curvature plays a key role in the magnetic transport of topological materials. Yet, it is not clear whether the Berry curvature by itself can give rise to universal transport phenomena with specific scaling behaviors. In this work, based on the semiclassical Boltzmann formalism and the symmetry analysis, we show that the noncentrosymmetric distribution of the Berry curvature generally results in linear magnetoresistivity and thermoconductivity both exhibiting the B-scaling behavior. We then study such kind of topological linear magnetoresistivity in the 2D MnBi2Te4 flakes and the 3D spin-orbit-coupled electron gas, the former showing good agreement with the experimental observations. The difference between our mechanism and the conventional anisotropic magnetoresistance is elucidated. Our theory proposes a universal scenario for the topological linear magnetoresistivity and thermoconductivity and predicts such effects to occur in various materials, which also provides a reasonable explanation for the recent observations of linear magnetoresistivity

Effects of supplementing lactic acid bacteria on fecal microbiota, total cholesterol, triglycerides and bile acids in rats.

Background: Probiotics (LAB) are normal components of the intestinal micro-flora in both humans and animals and its ingestion in decreasing the risk of atherosclerosis. In addition, the potential health effects of LAB were investigated by monitoring changes in intestinal micro-flora and lipid metabolism in a rat model.Materials and Methods: Rats were randomly assigned into four treatments and fecal samples were obtained on days 1, 3, 5, 9 and 14，to evaluate fecal micro biota, total cholesterol (TC), triglycerides (TG) and bile acids in rats (TBA).Results: The results indicated that Lactobacillus plantarum strain L.p X3-2B increased fecal lactic acid bacteria(LAB) and Bifidobacterium while resisting the growth of harmful bacteria. Viable counts of LAB and Bifidobacterium reached 8 log cfu/mL after feeding for 14 days. Fecal pH in the control group was high in comparison with the treatments at all times. Treatment increased the excretion of triglycerides (TG), total cholesterol (TC) and total bile acid (TBA). The results indicate that LAB and Bifidobacterium induce a positive correlation with fecal TC, TG and TBA and a negative correlation with fecal Enterobacteriaceae, Enterococcus and Escherichia coli.Conclusion: Lactic acid bacteria screened from Inner Mongolia native meat sausages in China had cholesterol-lowering effect.Keywords: Lactic acid bacteria, fecal micro biota, TC, TG, TB

Targeting Thioredoxin Reductase 1 Reduction in Cancer Cells Inhibits Self-Sufficient Growth and DNA Replication

Thioredoxin reductase 1 (TR1) is a major redox regulator in mammalian cells. As an important antioxidant selenoprotein, TR1 is thought to participate in cancer prevention, but is also known to be over-expressed in many cancer cells. Numerous cancer drugs inhibit TR1, and this protein has been proposed as a target for cancer therapy. We previously reported that reduction of TR1 levels in cancer cells reversed many malignant characteristics suggesting that deficiency in TR1 function is antitumorigenic. The molecular basis for TR1's role in cancer development, however, is not understood. Herein, we found that, among selenoproteins, TR1 is uniquely overexpressed in cancer cells and its knockdown in a mouse cancer cell line driven by oncogenic k-ras resulted in morphological changes characteristic of parental (normal) cells, without significant effect on cell growth under normal growth conditions. When grown in serum-deficient medium, TR1 deficient cancer cells lose self-sufficiency of growth, manifest a defective progression in their S phase and a decreased expression of DNA polymerase α, an enzyme important in DNA replication. These observations provide evidence that TR1 is critical for self-sufficiency in growth signals of malignant cells, that TR1 acts largely as a pro-cancer protein and it is indeed a primary target in cancer therapy

Earthquake Forecast via Neutrino Tomography

We discuss the possibility of forecasting earthquakes by means of (anti)neutrino tomography. Antineutrinos emitted from reactors are used as a probe. As the antineutrinos traverse through a region prone to earthquakes, observable variations in the matter effect on the antineutrino oscillation would provide a tomography of the vicinity of the region. In this preliminary work, we adopt a simplified model for the geometrical profile and matter density in a fault zone. We calculate the survival probability of electron antineutrinos for cases without and with an anomalous accumulation of electrons which can be considered as a clear signal of the coming earthquake, at the geological region with a fault zone, and find that the variation may reach as much as 3% for $\bar \nu_e$ emitted from a reactor. The case for a $\nu_e$ beam from a neutrino factory is also investigated, and it is noted that, because of the typically high energy associated with such neutrinos, the oscillation length is too large and the resultant variation is not practically observable. Our conclusion is that with the present reactor facilities and detection techniques, it is still a difficult task to make an earthquake forecast using such a scheme, though it seems to be possible from a theoretical point of view while ignoring some uncertainties. However, with the development of the geology, especially the knowledge about the fault zone, and with the improvement of the detection techniques, etc., there is hope that a medium-term earthquake forecast would be feasible.Comment: 6 pages, 4 figures, 1 tabl

Transcriptional regulation of the urokinase receptor (u-PAR) - A central molecule of invasion and metastasis

The phenomenon of tumor-associated proteolysis has been acknowledged as a decisive step in the progression of cancer. This short review focuses on the urokinase receptor (u-PAR), a central molecule involved in tumor-associated invasion and metastasis, and summarizes the transcriptional regulation of u-PAR. The urokinase receptor (u-PAR) is a heavily glycosylated cell surface protein and binds the serine protease urokinase specifically and with high affinity. It consists of three similar cysteine-rich repeats and is anchored to the cell membrane via a GPI-anchor. The u-PAR gene comprises 7 exons and is located on chromosome 19q13. Transcriptional activation of the u-PAR promoter region can be induced by binding of transcription factors (Sp1, AP-1, AP-2, NF-kappaB). One current study gives an example for transcriptional downregulation of u-PAR through a PEA3/ets transcriptional silencing element. Knowledge of the molecular regulation of this molecule in tumor cells could be very important for diagnosis and therapy in the near future

Finite temperature calculations for the bulk properties of strange star using a many-body approach

We have considered a hot strange star matter, just after the collapse of a supernova, as a composition of strange, up and down quarks to calculate the bulk properties of this system at finite temperature with the density dependent bag constant. To parameterize the density dependent bag constant, we use our results for the lowest order constrained variational (LOCV) calculations of asymmetric nuclear matter. Our calculations for the structure properties of the strange star at different temperatures indicate that its maximum mass decreases by increasing the temperature. We have also compared our results with those of a fixed value of the bag constant. It can be seen that the density dependent bag constant leads to higher values of the maximum mass and radius for the strange star.Comment: 21 pages, 2 tables, 12 figures Astrophys. (2011) accepte

An assessment of aerosol‐cloud interactions in marine stratus clouds based on surface remote sensing

An assessment of aerosol-cloud interactions (ACI) from ground-based remote sensing under coastal stratiform clouds is presented. The assessment utilizes a long-term, high temporal resolution data set from the Atmospheric Radiation Measurement (ARM) Program deployment at Pt. Reyes, California, United States, in 2005 to provide statistically robust measures of ACI and to characterize the variability of the measures based on variability in environmental conditions and observational approaches. The average ACIN (= dlnNd/dlna, the change in cloud drop number concentration with aerosol concentration) is 0.48, within a physically plausible range of 0–1.0. Values vary between 0.18 and 0.69 with dependence on (1) the assumption of constant cloud liquid water path (LWP), (2) the relative value of cloud LWP, (3) methods for retrieving Nd, (4) aerosol size distribution, (5) updraft velocity, and (6) the scale and resolution of observations. The sensitivity of the local, diurnally averaged radiative forcing to this variability in ACIN values, assuming an aerosol perturbation of 500 c-3 relative to a background concentration of 100 cm-3, ranges betwee-4 and -9 W -2. Further characterization of ACI and its variability is required to reduce uncertainties in global radiative forcing estimates