Sintering of hierarchically-structured boron carbide for toughening and multi- functionality

Boron carbide is light-weight, is thermally stable, has high hardness/stiffness, and is multi-functional (semiconducting, thermoelectric, and high neutron absorption cross-section). Boron carbide has been of interest for applications in extreme environments, including turbine engines, protection armor against impact, heat, and radiation, but such application is currently limited due to its brittleness and low sinterability. The toughening of ceramics has been investigated for many years as a light-weight, thermally/chemically stable alternative to structural materials. Among many methods, ceramic micro-fibers implementation has been effective, and further toughening is expected though engineering of matrices, specifically by implementing intentionally weak interphases to provide locally controlled deformation and thus energy dissipation within matrices. For example, in the past we experimentally studied the potentials of nano-porosity introduction into ceramics on deformation behaviors, by indenting on a model system of anodic aluminum oxide. Normally, porosity in ceramics is regarded as the defect, but we identified that, when pore size is below 100 nm, nanopores deform in a controlled manner (collapse or shear band, see Figure 1a), contributing to fracture toughness increase. Meanwhile, introduction of nano-porosity resulted in stiffness and hardness decrease. Please download the PDF file for full content

Dynamic response of overpass cable-stayed bridge due to aerodynamic effect of high-speed train

The objective of this paper is to evaluate the aerodynamic effect of the high-speed train on an overpass cable-stayed bridge completed by the rotation method. Computational fluid dynamics software Fluent was used in this numerical study. Flow field under a high-speed train has been considered as a viscous, compressible and unsteady flow. Flow model of high-speed train and bridge was established by the sliding mesh approach. Simulated train is passing 7.25 m underneath the bridge with a speed of 350 km/h and 500 km/h to obtain the time history of lifting force, resistance force and torque such that those data can be later applied to the bridge under different construction stages. Numerical results showed that larger aerodynamic response was observed when the tail of the train passed the bridge and the maximum response was observed right above the train. As for current scenario, the aerodynamic effect on such type of concrete cable-stayed bridge could be ignored but it should be checked when structure became lighter (such as steel structure)

Genetic Polymorphism in a VEGF-Independent Angiogenesis Gene ANGPT1 and Overall Survival of Colorectal Cancer Patients after Surgical Resection

Background The VEGF-independent angiogenic signaling plays an important role in the development of colorectal cancer (CRC). However, its implication in the clinical outcome of CRC has not been reported. This study aimed to investigate the association between genetic variations in several major VEGF-independent signaling pathway genes and the overall survival of CRC patients. Methods Seven single nucleotide polymorphisms (SNPs) in four important VEGF-independent angiogenic genes (ANGPT1, AMOT, DLL4 and ENG) were genotyped in a Chinese population with 408 CRC patients. Results One SNP, rs1954727 in ANGPT1, was significantly associated with CRC overall survival. Compared to patients with the homozygous wild-type genotype of rs1954727, those with heterozygous and homozygous variant genotypes exhibited a favorable overall survival with a hazard ratio (HR) of 0.89 (95% confidence interval [CI] 0.55–1.43, P = 0.623), and 0.32 (95% CI 0.15–0.71, P = 0.005), respectively (P trend = 0.008). In stratified analysis, this association remained significant in patients receiving chemotherapy (P trend = 0.012), but not in those without chemotherapy. We further evaluated the effects of chemotherapy on CRC survival that was stratified by rs1954727 genotypes. We found that chemotherapy resulted in a significantly better overall survival in the CRC patients (HR = 0.44, 95% CI 0.26–0.75, P = 0.002), which was especially prominent in those patients with the heterozygous genotype of rs1954727 (HR = 0.45, 95%CI 0.22–0.92, P = 0.028). Conclusion Our data suggest that rs1954727 in ANGPT1 gene might be a prognostic biomarker for the overall survival of CRC patients, especially in those receiving chemotherapy, a finding that warrants validation in larger independent populations

Genetic Variations in the Regulator of G-Protein Signaling Genes Are Associated with Survival in Late-Stage Non-Small Cell Lung Cancer

The regulator of G-protein signaling (RGS) pathway plays an important role in signaling transduction, cellular activities, and carcinogenesis. We hypothesized that genetic variations in RGS gene family may be associated with the response of late-stage non-small cell lung cancer (NSCLC) patients to chemotherapy or chemoradiotherapy. We selected 95 tagging single nucleotide polymorphisms (SNPs) in 17 RGS genes and genotyped them in 598 late-stage NSCLC patients. Thirteen SNPs were significantly associated with overall survival. Among them, rs2749786 of RGS12 was most significant. Stratified analysis by chemotherapy or chemoradiation further identified SNPs that were associated with overall survival in subgroups. Rs2816312 of RGS1 and rs6689169 of RGS7 were most significant in chemotherapy group and chemoradiotherapy group, respectively. A significant cumulative effect was observed when these SNPs were combined. Survival tree analyses identified potential interactions between rs944343, rs2816312, and rs1122794 in affecting survival time in patients treated with chemotherapy, while the genotype of rs6429264 affected survival in chemoradiation-treated patients. To our knowledge, this is the first study to reveal the importance of RGS gene family in the survival of late-stage NSCLC patients

PAS: Prediction-based Adaptive Sleeping for Environment Monitoring in Sensor Networks

Energy efficiency has proven to be an important factor dominating the working period of WSN surveillance systems. Intensive studies have been done to provide energy efficient power management mechanisms. In this paper, we present PAS, a Prediction-based Adaptive Sleeping mechanism for environment monitoring sensor networks to conserve energy. PAS focuses on the diffusion stimulus (DS) scenario, which is very common and important in the application of environment monitoring. Different with most of previous works, PAS explores the features of DS spreading process to obtain higher energy efficiency. In PAS, sensors determine their sleeping schedules based on the observed emergency of DS spreading. While sensors near the DS boundary stay awake to accurately capture the possible stimulus arrival, the far away sensors turn into sleeping mode to conserve energy. Simulation experiment shows that PAS largely reduces the energy cost without decreasing system performance. 1

KQStream: Kindred-Based QoS-Aware Live Media Streaming in Heterogeneous Peer-to-Peer Environments

This paper presents the design of a Kindred-based QoS-aware Live Media Streaming (KQStream) system in heterogeneous peer-to-peer environments. Motivated by the Multiple Description Coding technique, we propose a novel kindred-based approach to construct a peer-to-peer overlay topology. To achieve QoS-awareness during the streaming process, we propose a dynamic QoS-aware regulating technique which takes into account of user’s preference, network bandwidth and buffer size. With the integration of the two proposed techniques, KQStream provides more flexibility in heterogeneous peer-to-peer environments and configurable playback with dynamic QoS-aware regulating. 1