某专用局域网优化设计与验证

针对某专用局域网的现状,提出用两台汇聚交换机加OSPF协议代替原来的静态路由,实现负载分担的优化方案.使用华为eNSP模拟器进行验证,重点验证等价路由情况下的路由优化.验证结果表明该优化方案可行、有效.     

Enterocins: Classification,Synthesis, Antibacterial Mechanisms and Food Applications

Enterococci, a type of lactic acid bacteria, are widely distributed in various environments and are part of the normal flora in the intestinal tract of humans and animals. Although enterococci have gradually evolved pathogenic strains causing nosocomial infections in recent years, the non-pathogenic strains have still been widely used as probiotics and feed additives. Enterococcus can produce enterocin, which are bacteriocins considered as ribosomal peptides that kill or inhibit the growth of other microorganisms. This paper reviews the classification, synthesis, antibacterial mechanisms and applications of enterocins, and discusses the prospects for future research.     

Estrogenic Activity of Mycoestrogen (3β,5α,22E)-Ergost-22-en-3-ol via Estrogen Receptor α-Dependent Signaling Pathways in MCF-7 Cells

Armillariella tabescens (Scop.) Sing., a mushroom of the family Tricholomataceae, has been used in traditional oriental medicine to treat cholecystitis, improve bile secretion, and regulate bile-duct pressure. The present study evaluated the estrogen-like effects of A. tabescens using a cell-proliferation assay in an estrogen-receptor-positive breast cancer cell line (MCF-7). We found that the methanol extract of A. tabescens fruiting bodies promoted cell proliferation in MCF-7 cells. Using bioassay-guided fractionation of the methanol extract and chemical investigation, we isolated and identified four steroids and four fatty acids from the active fraction. All eight compounds were evaluated by E-screen assay for their estrogen-like effects in MCF-7 cells. Among the tested isolates, only (3β,5α,22E)-ergost-22-en-3-ol promoted cell proliferation in MCF-7 cells; this effect was mitigated by the ER antagonist, ICI 182,780. The mechanism underlying the estrogen-like effect of (3β,5α,22E)-ergost-22-en-3-ol was evaluated using Western blot analysis to detect the expression of extracellular signal-regulated kinase (ERK), phosphatidylinositol 3-kinase (PI3K), Akt, and estrogen receptor α (ERα). We found that (3β,5α,22E)-ergost-22-en-3-ol induced an increase in phosphorylation of ERK, PI3K, Akt, and ERα. Together, these experimental results suggest that (3β,5α,22E)-ergost-22-en-3-ol is responsible for the estrogen-like effects of A. tabescens and may potentially aid control of estrogenic activity in menopause.     

纤维素衍生物手性固定相研究进展

本文从用作手性固定相的纤维素衍生物种类、纤维素衍生物手性固定相制备方法及其在高效液相色谱中的应用三个方面介绍了国内外近年来的研究进展,并展望了该领域今后的研究方向。     

谐波电流发射超标的分析和改进

分析谐波电流发射测试失败原由,探讨谐波电流发射抑制措施;指出在 AC 输入回路和整流桥之间加滤波器难以使谐波电流发射值降低到标准规定限值以内。可通过在源头将产生谐波的关键零部件隔离、采用功率因素校正和在源头对波形失真进行补偿等措施使谐波电流控制在标准限值以内。     

黄芪中微量元素的形态分析

按照传统煎煮法对中药黄芪中铜、锌、铁、镁、钙和铬6种元素进行提取;用微孔滤膜分离提取液中的可溶态与悬浮态;利用大孔吸附树脂柱对可溶态中的有机态与无机态进行分离;采用火焰原子吸收光谱法对各种形态中的6种元素进行测定。结果显示:黄芪中6种元素的总提取率在44.0%~74.4%,浸留比在79·4%~293.8%,悬浮态颗粒吸附率在10%左右,可溶态中铬的有机态与无机态的比例为114.6%,铜、锌、铁、镁、钙的有机态与无机态的比例在3.7%~43.5%。该法对各元素的加标回收率在96.8%~103.1%;相对标准偏差小于1.5%。     

CaPtAs: A new noncentrosymmetric superconductor

We report the discovery of a new noncentrosymmetric superconductor CaPtAs.It crystallizes in a tetragonal structure(space group I41md,No.109),featuring three dimensional honeycomb networks of Pt-As and a much elongated c-axis(a=b=4.18?,and c=43.70?).The superconductivity of CaPtAs with Tc=1.47 K was characterized by means of electrical resistivity,specific heat,and ac magnetic susceptibility.The electronic specific heat Ce(T)/T shows evidence for a deviation from the behavior of a conventional BCS superconductor,and can be reasonably fitted by a p-wave model.The upper critical fieldμ0Hc2 of CaPtAs exhibits a moderate anisotropy,with an in-plane value of around 204 mT and an out-of-plane value of 148 mT.Density functional theory calculations indicate that the Pt-5 d and As-4 p orbitals mainly contribute to the density of states near the Fermi level,showing that the Pt-As honeycomb networks may significantly influence the superconducting properties.     

Highly efficient excitation of LP_(01) mode in ring-core fibers by tapering for optimizing OAM generation

We have demonstrated the highly efficient excitation of the linearly polarized mode(LP01)in ring-core fibers(RCFs)by tapering the spliced point between the RCF and the standard single-mode fiber(SMF)to optimize all-fiber orbital angular momentum(OAM)generation.The tapering technique has been investigated theoretically and experimentally.Before tapering,only 50%of light can be coupled from SMFs to RCFs.The modal interference spectrum with an extinction ratio(ER)of～9 dB is observed,showing that higher-order modes are excited in RCF.By tapering the spliced point,90%of light is coupled,and the ER is minimized to be～2 dB,indicating that the higher-order modes are effectively suppressed by tapering.Such tapered spliced points of RCF–SMF are further applied for all-fiber OAM generation.The efficiencies of OAM+1 and OAM?1 generation are found to be enhanced by approximately 11.66%and 12.41%,respectively,showing that the tapered spliced point of the RCF–SMF is a feasible way to optimize OAM generation.     

大鼠体内复方清开灵代谢物的分析

建立了复方中药清开灵代谢物的液相色谱-质谱/质谱分析方法。采用Phenomenex Luna C18色谱柱,以0.1%甲酸(A)及V(甲醇)∶和V(乙腈)=4∶1混合液(B)作流动相,采用梯度洗脱(0 min,B为0%;33min,B为60%;66 min,B为88%;75 min,B为100%),流速:0.5 mL/min,离子阱质谱负离子模式进行检测。通过差谱方法对可能的代谢物进行快速搜索。对发现的重要的代谢物根据分子量以及多级质谱的碎片离子数据,结合体内代谢反应规律,进行指认和结构鉴定。共鉴定了3个主要的代谢物,其中一个为黄芩苷的代谢物,另两个为绿原酸的代谢物,后两个代谢物未见文献报道。本实验为研究复方中药复杂体系体内的代谢产物提供了一个有效而且快捷的模式。     

Partial Oxidation of Methane to Synthesis Gas over Hexaaluminates LaMAl11O19-δ catalysts

A series of M-substituted hexaaluminates LaMAl11O19-δ (M=Fe, Co, Ni, Mn, and Cu)were prepared and characterized by XRD, XPS, TPR and TGA techniques, respectively. They exhibited different reducibility and catalytic activity for partial oxidation of methane (POM) to synthesis gas. Among the LaMAl11O19-δ samples, LaNiAl11O19-δ showed the best catalytic activity for the topic reaction and selectivity for synthesis gas at 780 ℃ for 2 h. The conversion of CH4 was over 99.2%, and the product selectivity for both CO and H2 was above 90.3%.