37Mn5连铸坯高温热塑性的研究

在Gleeble-1500D热模拟机上,针对37Mn5钢连铸坯,进行了热塑性测试.分析了37Mn5试样的显微组织及试样断口性质与塑性的关系.研究了第Ⅲ脆性区的脆化原因.实验结果表明:在1 300℃至800℃区间存在两个脆性温度区,第Ⅲ脆性温度域为900～800 ℃,其断面收缩率ψ=60.23%～29.61%;为指导37Mn5管坯钢的生产实践提供理论依据.     

Growth and morphology of ultra-thin Al films on liquid substrates studied by atomic force microscopy

We study the growth process and morphology evolution of the ultra-thin Al films deposited on silicone oil surfaces by using atomic force microscopy. Initially, the deposited atoms nucleate and form compact clusters on the liquid surfaces. Then the clusters perform Brownian motion and adhere upon impact, which results in the ramified islands. Finally a continuous film forms as the nominal film thickness d increases. The mean size of the grains in the compact clusters and ramified islands is of the order of 10¹ nm. The ultra-thin Al films exhibit a self-affine surface morphology and therefore the dynamic scaling analysis is performed. It is found that the growth exponent β = 0.23 ± 0.05. In the range d = 0.1-1.0 nm, the roughness exponent α varies from α ≥ 1 to < 1. The physical interpretation for the crossover of the scaling behavior is presented.     

黄芩苷体外调控乳腺癌细胞表达TIMP2的实验研究

目的: 探讨黄芩苷对Bcap-37 细胞生长及TIMP2 表达的影响。方法: 体外细胞培养、MTT 法测定不同浓度黄芩苷对Bcap-37 细胞生长曲线的影响, RT-PCR 、Western blot 方法研究不同浓度黄芩苷对Bcap-37 细胞TIMP2 的影响。结果: 黄芩苷对Bcap-37 细胞的生长抑制呈浓度依赖关系;黄芩苷对Bcap-37 细胞TIMP2 在mRNA 水平、蛋白水平呈浓度依赖关系, 小剂量上调, 高剂量下调。结论: 黄芩苷对人乳腺癌Bcap-37 细胞生长有抑制作用, 可能与肿瘤细胞TIMP2 的下调有关。     

Preparation and mechanical properties of a new Zr–Al–Ti–Cu–Ni–Be bulk metallic glass

In this paper, a new Zr₃₇Al₁₀Ti_12.5Cu_11.25Ni₉Be_20.25 bulk metallic glass is reported. The present alloy was prepared by water quenching in a silica tube of φ10×85 mm. The amorphicity of the quenched bulk samples was examined using X-ray diffraction analysis and optical microscopy. The thermal stability was evaluated by differential scanning calorimetry (DSC) at a heating rate of 10 K/min. The characteristic data of the bulk metallic glass are presented, including glass transition temperature (T_g) and crystallization temperature (T_x). Results show that the present alloy exhibits large glass forming ability. For comparison with the well-known Zr–Ti–Cu–Ni–Be metallic glass, it was found that aluminum has a little effect on the vitrification of the present alloy but influences physical properties. Specifically, Al enhances the Young's modulus by 21.4% and Vickers hardness by 20% and reduces density by 7.2%.     

37Ar用于视察地下核试验的尝试

对地下核爆漏气体中放射性核素＾３７Ａｒ进行取样,提纯及测量并研究了泄漏速率随时间位置的变化规律。结果表明：监测土壤中＾３７Ａｒ的含量可有效地核查地下核试验。     

Chl1, an ATP-Dependent DNA Helicase,Inhibits DNA:RNA Hybrids Formation at DSB Sites to Maintain Genome Stability in S. pombe

As an ATP-dependent DNA helicase, human ChlR1/DDX11 (Chl1 in yeast) can unwind both DNA:RNA and DNA:DNA substrates in vitro. Studies have demonstrated that ChlR1 plays a vital role in preserving genome stability by participating in DNA repair and sister chromatid cohesion, whereas the ways in which the biochemical features of ChlR1 function in DNA metabolism are not well understood. Here, we illustrate that Chl1 localizes to double-strand DNA break (DSB) sites and restrains DNA:RNA hybrid accumulation at these loci. Mutation of Chl1 strongly impairs DSB repair capacity by homologous recombination (HR) and nonhomologous end-joining (NHEJ) pathways, and deleting RNase H further reduces DNA repair efficiency, which indicates that the enzymatic activities of Chl1 are needed in Schizosaccharomyces pombe. In addition, we found that the Rpc37 subunit of RNA polymerase III (RNA Pol III) interacts directly with Chl1 and that deletion of Chl1 has no influence on the localization of Rpc37 at DSB site, implying the role of Rpc37 in the recruitment of Chl1 to this site.     

Pb(Zr0.52Ti0.48)O3/TiNi multilayered heterostructures on Si substrates for smart systems

Ferroelectric/shape memory alloy thin film multilayered heterostructures possess both sensing and actuating functions and are considered to be smart. In this article, Pb(Zr_0.52Ti_0.48)O₃ (PZT) ferroelectric thin films and Ti-riched TiNi shape memory alloy thin films have been deposited on Si and SiO₂/Si substrates in the 400-600 °C temperature range by pulsed laser deposition technique. Deposition processing, microstructure and surface morphology of these films are described. The TiNi films deposited at 500 °C had an austenitic B2 structure with preferred (110) orientation. The surfaces of the films were very smooth with the root-mean-square roughness on a unit cell level. The structure of the TiNi films had a significant influence on that of the subsequently deposited PZT films. The single B2 austenite phase of the TiNi favored the growth of perovskite PZT films. The PZT/TiNi heterostructures with the PZT and TiNi films respectively deposited at 600 and 500 °C exhibited a polarization-electric field hysteresis behavior with a leakage current of about 2 × 10^− 6 A/cm².     

IL-33 and IL-37: A Possible Axis in Skin and Allergic Diseases

Interleukin (IL)-37 and IL-33 are among the latest cytokines identified, playing a role in several inflammatory conditions, spanning from systemic conditions to tumors to localized diseases. As newly discovered interleukins, their role is still scarcely understood, but their potential role as therapeutic targets or disease activity markers suggests the need to reorganize the current data for a better interpretation. The aim of this review is to collect and organize data produced by several studies to create a complete picture. The research was conducted on the PubMed database, and the resulting articles were sorted by title, abstract, English language, and content. Several studies have been assessed, mostly related to atopic dermatitis and immunologic pathways. Collective data demonstrates a pro-inflammatory role of IL-33 and an anti-inflammatory one for IL-37, possibly related to each other in an IL-33/IL-37 axis. Although further studies are needed to assess the safety and plausibility of targeting these two interleukins for patients affected by skin conditions, the early results indicate that both IL-33 and IL-37 represent markers of disease activity.     

Selection of optimal processing condition during abrasive wear of in-situ ZA-37/TiCp composites using MCDM technique

The present study attestation has been made towards microstructural characterization, and thereafter investigation on the optimum abrasive wear processing condition of newly developed insitu TiC reinforced ZA37 alloys. The MMC's have been processed by advanced vortex creating in-situ technique. Effects of significant influencing variables like abrasive grain size, percentage of reinforcement, applied load, and sliding velocity on abrasive wear characteristics via wear rates, coefficient of friction and interface temperature was investigated thoroughly. A newly developed, GRA based hybrid RSM approach has been implemented to investigate the optimum processing condition within the specified wear domain. The non-linear characteristics of response variables were demonstrated by developing a quadratic regression model which was the functions of independent process variables. ANOVA has been implemented to identify the percentage contribution of each process variables towards responses. The observation revealed that the abrasive grain size, percentage of reinforcement and applied load contributed significantly to the developed model and thereby on the wear characteristics. Improvements were noticed on the response characteristics attained by implementing both the GRSM and desirability approaches. Significant deviations were obtained on responses (15% on wear rates, 20% on COF and 4% on temperature) implementing two phases of optimal parametric combinations predicted by GRA based hybrid approach. Optical surface profile and corresponding micrograph represent the improved surface quality (R_a, 0.83 μm vs. R_a, 1.18 μm) and textures employing the GRSM based hybrid approach indicated settings of the process parameter.     

Comparison of dry wear characteristics of two abrasion-resistant steels: Q/T C1095 and 15B37H

The dry reciprocating wear characteristics of two abrasion-resistant steels, C1095 and 15B37H, against an abrasive material were studied. Results showed that abrasive wear and surface fatigue were the primary wear mechanisms. The wear failure of the steels was related to frictional softening during wear.