烧结?Al?B4C 复合材料的往复滑动磨损性能

采用粉末冶金法制备了不同 B₄C 含量（1wt%、6wt%、15wt% 和 30wt%）的碳化硼增强铝基复合材料（Al?B₄C）,并研究了 B4C 含量对其力学性能和摩擦学行为的影响。在7 N载荷下, Al?30B₄C 复合材料的密度最高 (~2.54 g/cm3)、孔隙率最低 (4%)、维氏硬度最高 (HV ~75)、重量损失最低 (0.4 mg) 和比磨损率最低 (0.00042 mm3/ (N·m)),与纯铝相比,硬度提高167%,失重降低75.8%,比磨损率降低76.7%。此外,磨损表面的扫描电镜图像显示,Al?B₄C复合材料在7 N载荷下的最窄磨损槽为0.85 mm,主要磨损机制为磨粒磨损机制。根据摩擦分析,表面之间的摩擦系数随着碳化硼含量的增加和外加载荷的减少而增加。总之,就 Al?B₄C 复合材料的摩擦学和力学性能而言,B₄C 是一种有效的增强材料。     

Microstructure,mechanical properties and formability of friction stir welded dissimilar materials of IF-steel and 6061 Al alloy

AA 6061 alloy and interstitial-free(IF)steel plates were joined by the friction stir welding(FSW)method,and the microstructure,mechanical properties,and biaxial stretch formability of the friction stir welded(FSWed)parts were investigated.The results indicate that the FSWed parts showed optimum tensile strength during FSW with the 0.4-mm offset position of the tool.The Fe4Al13 intermetallic compound formed in the defect-free intersection of AA 6061 and IF-steel plates during FSW.The hardness of the IF-steel part of the FSWed region increased almost 90%relative to its initial hardness of HV0.2 105.The tensile and yield strengths of FSWed regions were approximately 170 MPa and 145 MPa,respectively.According to the formability tests,the Erichsen Index(EI)of the IF-steel,AA 6061,and the FSWed samples were determined to be 2.9 mm,1.9 mm,and 2.1 mm,respectively.The EI of the FSWed sample was almost the same as that of the AA 6061 alloy.However,it decreased compared with that of the IF-steel.The force at EI(FEI)was approximately 1180 N for the FSWed condition.This value is approximately 70%higher than that of AA 6061 alloy.     

Timing of plant immune responses by a central circadian regulator

The principal immune mechanism against biotrophic pathogens in plants is the resistance (R)-gene-mediated defence. It was proposed to share components with the broad-spectrum basal defence machinery. However, the underlying molecular mechanism is largely unknown. Here we report the identification of novel genes involved in R-gene-mediated resistance against downy mildew in Arabidopsis and their regulatory control by the circadian regulator, CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1). Numerical clustering based on phenotypes of these gene mutants revealed that programmed cell death (PCD) is the major contributor to resistance. Mutants compromised in the R-gene-mediated PCD were also defective in basal resistance, establishing an interconnection between these two distinct defence mechanisms. Surprisingly, we found that these new defence genes are under circadian control by CCA1, allowing plants to 'anticipate' infection at dawn when the pathogen normally disperses the spores and time immune responses according to the perception of different pathogenic signals upon infection. Temporal control of the defence genes by CCA1 differentiates their involvement in basal and R-gene-mediated defence. Our study has revealed a key functional link between the circadian clock and plant immunity.     

第二种服务可选的M／M／1排队模型状态空间及对偶空间的完备性

当μ1（x）=μ1,μ2（x）=μ2时,研究了第二种服务可选的M／M／1排队模型的状态空间和对偶空间的完备性。     

维药异常黑胆质成熟剂对异常黑胆质型肝癌模型作用机制的血清代谢组学研究

 依托核磁共振氢谱(¹H-NMR)技术,探讨异常黑胆质成熟剂(ASM)对异常黑胆质型肝癌模型代谢谱的变化及其作用机制。根据维吾尔医学理论,建立维吾尔医异常黑胆质型肝癌病证大鼠模型,运用核磁共振氢谱技术检测以不同剂量ASM 灌胃大鼠的血清代谢物含量变化,分段积分后采用正交偏最小二乘判别(OPLS-DA)对¹H-NMR 谱数据进行模式识别分析。将1HNMR谱信息用PLS-DA 分析可以把异常黑胆质型肝癌组和ASM 低、中、高剂量组之间大鼠血清代谢谱变化区分开,发现与异常黑胆质肝癌组相比,在ASM 低剂量组大鼠的血清中α-葡萄糖,β-葡萄糖和牛磺酸的含量上升,而在ASM 中剂量组大鼠的血清中同样这三者也有升高,并且一些必需氨基酸,如亮氨酸、缬氨酸、丙氨酸、组氨酸含量升高,乳酸降低,并且差异有统计学意义(P<0.05),而在ASM 高剂量组大鼠的血清中变化无此趋势。异常黑胆质成熟剂通过提高支链氨基酸的含量,加速糖异生提高能量供应,降低乳酸堆积来调节异常黑胆质型肝癌模型的氨基酸代谢,糖代谢等能量代谢紊乱。     

Genetic consequences of postglacial colonization by the endemic Yarkand hare （Lepus yarkandensis） of the arid Tarim Basin

Orogenesis of the Qinghai-Tibetan Plateau,which occurred in a stepwise manner,contributed to the extreme aridity of the Tarim Basin,resulting in vulnerable and unstable ecosystems.Quaternary climatic oscillations may have affected the ecosystems and,consequently,the distributions and genetic structuring of the Tarim Basin’s biota.We used nucleotide sequence data from 2 mitochondrial (mt) DNA genes (Cyt b and the D-loop) to test hypotheses associated with the matrilineal and demographical histories of the Tarim Basin’s endemic Yarkand hare (Lepus yarkandensis).Range-wide sampling involving 20 populations and 224 individuals detected 126 haplotypes that clustered into 5 major lineages in both the phylogenetic tree and median-joining network.Populations from the northern and eastern Tarim Basin shared a similar history,as did those from the western and southern regions.Demographical analysis and genetic diversity estimations suggested that the western and southern regions might have served as glacial refugia for the Yarkand hare during Quaternary climatic oscillations.The distribution of the Yarkand hare,especially in the northern and eastern parts,probably represented 3 postglacial colonization events,dated to 0.21,0.090 and 0.054 MYA,which corresponded to known interglacial periods.Given the relatively complete geographic isolation between the eastern and southern populations,the Yarkand hare likely dispersed during postglacial periods from the southwest to the north,and then onward to the east.The absence of water likely forced the species into refugia,and this differed from other Pleistocene biogeographical drivers.The demographical and historical patterns have important implications for conservation.     

在一个供应链系统可靠性模型研究中出现的投影算子表达式及其应用

该文考虑一个供应链系统可靠性模型.首先指出此供应链系统的主算子所生成的正压缩C0-半群T(t)是拟紧算子,其次通过正压缩C0-半群T(t)的本质谱增长界性质和留数定理推出该模型研究中出现的投影算子的具体表达式,最后得到该供应链系统模型的时间依赖解指数收敛到其稳态解.     

A common genetic variant in the NOS1 regulator NOS1AP modulates cardiac repolarization

Extremes of the electrocardiographic QT interval, a measure of cardiac repolarization, are associated with increased cardiovascular mortality. We identified a common genetic variant influencing this quantitative trait through a genome-wide association study on 200 subjects at the extremes of a population-based QT interval distribution of 3,966 subjects from the KORA cohort in Germany, with follow-up screening of selected markers in the remainder of the cohort. We validated statistically significant findings in two independent samples of 2,646 subjects from Germany and 1,805 subjects from the US Framingham Heart Study. This genome-wide study identified NOS1AP (CAPON), a regulator of neuronal nitric oxide synthase, as a new target that modulates cardiac repolarization. Approximately 60% of subjects of European ancestry carry at least one minor allele of the NOS1AP genetic variant, which explains up to 1.5% of QT interval variation.     

论维吾尔医沙疗对骨质层的转移及力学特性的影响

本文以研究维吾尔医沙疗对骨质层的转移及力学性能的影响为目的,建立好股性关节炎模型的30只新西兰大白兔作为研究对象,由沙疗时间长短之差异将所有兔子分为三组并进行沙疗。在此期间进行四次CT扫描,计算出各股骨骨质层的总体积且统计分析骨质层的转移。取三组兔子左右股骨进行三点弯曲实验。实验结果表明,病态兔子股骨硬质骨和密质骨的增加速度比正常股骨低,而软质骨的减少速度基本一致;软质骨在向硬质骨和密质骨转化;正常兔子股骨的挠度、最大抗弯强度和最大抗弯正应力比病态兔子股骨要高,沙疗会促进股骨骨质层的转化,且改善股骨基本力学性能。     

哒嗪与3-庚基噻吩共聚物的合成及其表征

在二价镍配合物催化剂存在下,用3,6-二氯哒嗪与3-庚烷基-2,5-二溴噻吩格氏试剂共聚合成了哒嗪与烷基噻吩共聚物,并利用红外光谱(FT-IR),核磁共振谱(1H-NMR)等对其结构和性能进行了表征。该合成方法所得共聚物的收率为75%,而且溶解于DM F、DM SO、CHC l3等普通溶剂中。共聚物的紫外-可见吸收光谱(UV-v is)中在405 nm处观察到最大吸收峰。用荧光光谱(PL)和热重分析(TGA)对所得聚合物的荧光特性和热稳定性作了初步探讨。