物联网:机遇与挑战

物联网是指通过使用嵌入式传感器、致动器以及可以收集或传送对象信息的其他设备形成的物理关系网。通过分析从这些设备中收集的数据,可优化产品、服务和操作。这种技术最早、最知名的应用之一也许是在能源优化领域:传感器部署在整个电网可以帮助公用事业远程监控能源使用情况。但许多其他行业也引入了这种应用程序。例如一些保险公司现在提出一个计划,要求     

Crystallographic Studies of Cephalosporin Acylase from Pseudomonas sp. Strain 130

The cephalosporin acylases are a group of enzymes that hydrolyze cephalosporin C and/or glutaryl 7-aminocephalosporanic acid to produce ?-aminocephalosporanic acid. The cephalosporin acylase from Pseudomonas sp. strain 130 was crystallized in two different forms suitable for structural studies. A tetragonal crystal form diffracted to 0.24 nm belonged to the space group P41212. There was one αβ heterodimer per asymmetric unit. A second crystal form diffracted to 0.21nm belonged to the space group P21. There was four αβ heterodimers per asymmetric unit. The tetragonal crystal structure of CA-130 was determined using the multiwavelength anomalous diffraction method and the P21 crystal structure was then determined using the molecular replacement method.     

Reducing Zn diffusion in single axial junction InP nanowire solar cells for improved performance

In this work axial n-i-p junction InP nanowires were grown by selective-area metal organic vapor phase epitaxy (SA-MOVPE) technique with the growth sequence starting from n-segment. The optical properties and carrier lifetimes of the n-, i- and p-type segments were studied and compared using time-resolved photoluminescence (PL) and cathodoluminescence (CL) measurements. We demonstrate for the first time that CL is capable of resolving the electrical profile of the nanowires, namely the varied lengths of the n-, i- and p-segments, providing a simple and effective approach for nanowire growth calibration and optimization. The CL result was further confirmed by electron beam induced current (EBIC) and photocurrent mapping measurements performed from the fabricated single nanowire solar cell devices. It is revealed that despite a non-optimized device structure (very long n-region and short i-region), the n-i-p nanowire solar cells show improved power conversion efficiency (PCE) than the previously reported p-i-n (growth starts with p-segment) single nanowire solar cells due to reduced p-type dopant (Zn) diffusion during the growth of n-i-p solar cell structure.     

Effects of hydrogen peroxide on in vitro infection of Cryptosporidium parvum

The effect of hydrogen peroxide (H2O2) on Cryptosporidium parvum infection and the protective function of free radical scavengers were studied in cultured bovine fallopian tubes epithelial cells. H2O2 treatment at 500 μmol/L and 1 mmol/L significantly inhibited excystation of bleach-treated oocysts (p ＜ 0. O1 ). At 48 h postinoculation,H2O2 at 500 and 750 μmol/L resulted in a significant (p ＜ 0.01) decrease of C. parvum infection by 35.77% and 58.16% respectively in the cultured cells, when compared with the untreated control. Surprisingly, the infection was significantly increased from 22.21% to 39.33 % ( p ＜ 0.05) with lower concentration of H2 O2 (50 ～ 200 μmol/L). The inhibitory and stimulatory effects of H2O2 treatment on C. parvum infection were, to a certain extent, abolished in the presence of reduced glutathione or mannitol. These observations indicate that reactive oxygen species, such as H2O2, may play an important role in C. parvum infection.     

部分剪切连接的组合梁强度和延性性能

对部分剪切连接的钢－混凝土组合梁的截面特性进行了全过程分析,同时将计算机分析结果与简单的刚塑性手算方法进行比较,并对部分剪切连接的组合梁的强度和延性进行了探讨。     

告别测不准原理,欢迎量子缠结的到来:测不准的终结

爱因斯坦对玻尔,是科学上最著名的较量之一。在20世纪20年代后期和30年代前期,他们为物理学的未来而展开论战。爱因斯坦不能接受量子力学荒谬绝伦的无序性和不可知性,因此他设正了一连串精巧的思维实验来攻击这个理论。但是每当他似乎揭开了量子论核心问题上的不一致性时,玻尔（NichsBohr）却证明爱因斯坦是错误的。尽管量子力学有那些不尽如人意的成分,它还是获胜了。玻尔是用海森伯（WernerHeisedberg）的测不准原理来不断挫败爱因斯坦的进攻的。按照海森伯的原理,测量一电子或任何别的量子粒子的位置,就会扰乱它的动量Z而测量它…     

Loss of Trim24 (Tif1alpha) gene function confers oncogenic activity to retinoic acid receptor alpha

Hepatocellular carcinoma (HCC) is a major cause of death worldwide. Here, we provide evidence that the ligand-dependent nuclear receptor co-regulator Trim24 (also known as Tif1alpha) functions in mice as a liver-specific tumor suppressor. In Trim24-null mice, hepatocytes fail to execute proper cell cycle withdrawal during the neonatal-to-adult transition and continue to cycle in adult livers, becoming prone to a continuum of cellular alterations that progress toward metastatic HCC. Using pharmacological approaches, we show that inhibition of retinoic acid signaling markedly reduces hepatocyte proliferation in Trim24-/- mice. We further show that deletion of a single retinoic acid receptor alpha (Rara) allele in a Trim24-null background suppresses HCC development and restores wild-type expression of retinoic acid-responsive genes in the liver, thus demonstrating that in this genetic background Rara expresses an oncogenic activity correlating with a dysregulation of the retinoic acid signaling pathway. Our results not only provide genetic evidence that Trim24 and Rara co-regulate hepatocarcinogenesis in an antagonistic manner but also suggest that aberrant activation of Rara is deleterious to liver homeostasis.     

REDUCING FIBER LOSS IN LABORATORY-AND MILL-SCALE FLOTATION DEINKING USING SURFACTANT SPRAY TECHNOLOGY

INTRODUCTIONDuring the past few years, the use of recycled fiber has increased dramatically due to the shortage of fiber resources and restrictive environmental regulations on paper landfills. Since the successful application of flotation in the paper recycling industry from the minerals industry in 1980s, flotation deinking has become a necessary process for ink removal from wastepaper in many paper recycling mills. The deinking chemistry and the physicochemical interactions among air bub…     

腹腔镜肾部分切除术治疗局限性肾细胞癌27例

目的:探讨经腹腔镜肾部分切除术治疗局限性肾细胞癌的手术技巧和近期疗效.方法:选择T1期、单发肿瘤,平均肿瘤直径4.0 cm(3.0～7.0 cm)的局限性肾细胞癌27例, 术中用内镜bulldog钳阻断肾动脉;用剪刀或超声刀在距离肿瘤边缘0. 5～1.0 cm处进行局部切除;肾切除床内置Surgicel薄片卷垫后,间断缝合肾实质,创面边缘喷涂FloSeal明胶基质以防延迟出血.术中冰冻确定切缘阴性.结果:27例手术均获成功,无术中、术后并发症.手术时间平均110 min;热缺血时间20～55 min,平均32 min;术中出血量平均150 mL.术后随访平均6个月,未见肿瘤局部复发,未见转移.结论:腹腔镜肾部分切除术治疗局限性肾细胞癌安全可靠,短期随访效果肯定.     

Evidence for Efimov quantum states in an ultracold gas of caesium atoms

Systems of three interacting particles are notorious for their complex physical behaviour. A landmark theoretical result in few-body quantum physics is Efimov's prediction of a universal set of bound trimer states appearing for three identical bosons with a resonant two-body interaction. Counterintuitively, these states even exist in the absence of a corresponding two-body bound state. Since the formulation of Efimov's problem in the context of nuclear physics 35 years ago, it has attracted great interest in many areas of physics. However, the observation of Efimov quantum states has remained an elusive goal. Here we report the observation of an Efimov resonance in an ultracold gas of caesium atoms. The resonance occurs in the range of large negative two-body scattering lengths, arising from the coupling of three free atoms to an Efimov trimer. Experimentally, we observe its signature as a giant three-body recombination loss when the strength of the two-body interaction is varied. We also detect a minimum in the recombination loss for positive scattering lengths, indicating destructive interference of decay pathways. Our results confirm central theoretical predictions of Efimov physics and represent a starting point with which to explore the universal properties of resonantly interacting few-body systems. While Feshbach resonances have provided the key to control quantum-mechanical interactions on the two-body level, Efimov resonances connect ultracold matter to the world of few-body quantum phenomena.