Ballistic carbon nanotube field-effect transistors

A common feature of the single-walled carbon-nanotube field-effect transistors fabricated to date has been the presence of a Schottky barrier at the nanotube--metal junctions. These energy barriers severely limit transistor conductance in the 'ON' state, and reduce the current delivery capability--a key determinant of device performance. Here we show that contacting semiconducting single-walled nanotubes by palladium, a noble metal with high work function and good wetting interactions with nanotubes, greatly reduces or eliminates the barriers for transport through the valence band of nanotubes. In situ modification of the electrode work function by hydrogen is carried out to shed light on the nature of the contacts. With Pd contacts, the 'ON' states of semiconducting nanotubes can behave like ohmically contacted ballistic metallic tubes, exhibiting room-temperature conductance near the ballistic transport limit of 4e(2)/h (refs 4-6), high current-carrying capability (approximately 25 micro A per tube), and Fabry-Perot interferences at low temperatures. Under high voltage operation, the current saturation appears to be set by backscattering of the charge carriers by optical phonons. High-performance ballistic nanotube field-effect transistors with zero or slightly negative Schottky barriers are thus realized.     

Phylogenetic relationships of native and introduced Bemisia tabaci (Homoptera:Aleyrodidae) from China and India based on mtCOI DNA sequencing and host plant comparisons

Phylogenetic relationships for Bemisia tabaci were reconstructed by analysis of a ～780 bp fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene with an emphasis on geographic range and distribution among eight eudicot plant families that are common hosts of B. tabaci worldwide to elucidate key phylogeographic linkages between populations extant in China (n=31) and India (n=34). Bootstrap values for the Maximum Parsimony tree were highly robust for all major nodes involving the major Asian clade, subgroups, and sister groups within, at 92%—100%. Between-clade distances for the Southeast Asia and three other major clades, e.g. from sub-Sahara Africa, North Africa-Mediterranean, and the Americas, were approximately >16% divergent. Two major Asian subgroups (I, II) were resolved, which represented populations indigenous to the region, comprising two (I a, I b) and five (II a—e) sister groups, respectively, which diverged by 11%. Two distinct populations from sunflower in Hyderabad grouped separately within the two Asian subgroups. All other populations grouped uniquely within Asian subgroup II or I. The "B" biotype was identified in 23 collections from China at 97.3%—99.5% nucleotide identity with "B" biotype reference sequences; it was not identified in collections from India. The majority of haplotypes were associated with 3—4 plant families, with one exception that for sister group IId (sesame, India), it might be monophagous. Thus, B. tabaci from the southeastern and near eastern regions of the Asian continent comprise of a large number of ancestral, richly divergent, mostly polyphagous populations. This region is therefore hypothesized to constitute an important Old World center of diversification for the B. tabaci complex, together with sub-Saharan Africa.     

用于海水淡化堆的闪蒸器蒸汽发生系统

核电站蒸汽发生器出现故障的几率较高。为减少蒸汽发生的质量和体积 ,提出用降压闪蒸的方法来产生蒸汽以替代蒸汽发生器。结合 10 MW核供热堆海水淡化系统 ,分析了闪蒸器蒸汽发生系统的特点。改进设计后 ,闪蒸器的体积比蒸发器小 4 0 % ,质量小约 80 % ;使用闪蒸器旁路调节对改善运行特性起很大作用。该设计拟用于摩洛哥核能海水淡化示范系统中。     

Scenario planning: An investigation of the construct and its measurement

Scenario‐planning academicians and practitioners have been observing for more than three decades the importance of this method in dealing with environmental uncertainty. However, there has been no valid scale that may help organizational leaders to act in practice. Our review of prior studies identifies some problems related to conceptualization, reliability, and validity of this construct. We address these concerns by developing and validating a measure of scenario planning based on Churchill's paradigm (Journal of Marketing Research, 1979, 16, 64–73). Our data analysis follows from a sample of 133 managers operating in the healthcare field in France. To validate our scale, we used three approaches: first, an exploratory factor analysis; second, an examination of psychometric proprieties of all dimensions; and third, a confirmatory factor analysis. The results of this study indicate that scenario planning is a multidimensional construct composed of three dimensions: information acquisition, knowledge dissemination, and scenario development and strategic choices.     

Deciphering microRNA code in pain and inflammation: lessons from bladder pain syndrome

MicroRNAs (miRNAs), a novel class of molecules regulating gene expression, have been hailed as modulators of many biological processes and disease states. Recent studies demonstrated an important role of miRNAs in the processes of inflammation and cancer, however, there are little data implicating miRNAs in peripheral pain. Bladder pain syndrome/interstitial cystitis (BPS/IC) is a clinical syndrome of pelvic pain and urinary urgency/frequency in the absence of a specific cause. BPS is a chronic inflammatory condition that might share some of the pathogenetic mechanisms with its common co-morbidities inflammatory bowel disease (IBD), asthma and autoimmune diseases. Using miRNA profiling in BPS and the information about validated miRNA targets, we delineated the signaling pathways activated in this and other inflammatory pain disorders. This review projects the miRNA profiling and functional data originating from the research in bladder cancer and immune-mediated diseases on the BPS-specific miRNAs with the aim to gain new insight into the pathogenesis of this enigmatic disorder, and highlighting the common regulatory mechanisms of pain and inflammation.     

First observation and seasonal dynamics of the new invasive planktonic copepod Oithona davisae Ferrari and Orsi, 1984 along the southern Black Sea (Anatolian Coast)

The zooplankton species Oithona davisae is indigenous to coastal areas of Japan and the China Seas. It has, however, successfully invaded many other coastal marine regions such as San Francisco Bay, the Mediterranean Sea, the North Sea and the Black Sea. It is transported most probably in ballast water tanks. This is the first report of O. davisae in the coastal regions of the southern Black Sea (Anatolian coast). Based on monthly plankton sampling at two stations (Sürmene Bay), the seasonal dynamics of O. davisae were investigated. The highest abundance occurred at the coastal station (49,761 ind. m^?3) in December and in October at the offshore station (8896 ind. m^?3). The egg-carrying copepod O. davisae is more abundant in September (4571 ind. m^?3) at the coastal station and in August (952 ind. m^?3) at the offshore station. Expansion of this invasive copepod along the Black Sea coasts is reported by another country also. According to our results this invasive species may replace its native congener, Oithona nana. It can be hypothesized that O. davisae is one of the key species for energy transfer to the upper level of the food web from the microbial loop, which has recently become important in the Black Sea.     

(Ⅲ)m=0类二次系统的极限环问题,(Ⅰ)

从本文开始我们对(Ⅲ)m=0类二次系统的极限环问题作了一系统研究,按照其系数的各种不同情况分类讨论．本文考察l<1/2,01的情况,给出了极限环惟一性的一些结论,并指出有时在一个焦点外围可以存在两个极限环,同时分析了系统的拓扑结构的变化．