Subcarrier modulation for transmission of 1-Gbit/s channels over 500 m of 62.5-μm multimode fiber

The use of two different subcarriers at frequencies up to 5.5 GHz each transmitting 1 Gbit/s over 500 m of multimode fiber (MMF) is demonstrated. By transmitting the two subcarrier channels simultaneously alongside the baseband signal, an aggregate bit rate of 2.8 Gbit/s is possible.

Si_(0.75)Ge_(0.25)虚衬底上应变补偿Si/Si_(0.62)Ge_(0.38)量子阱发光

由于Si/SiGe异质结构的带阶差主要发生在价带,为实现高效率的发光,本文从理论上设计了在硅基Si_(1-x) Ge_x虚衬底上外延应变补偿的Si/S_(1-y) Ge_y(y>x)量子阱的能带结构,将量子阱对电子的限制势垒提高到100meV以上.在实验上,采用300℃生长的Ge量子点插入层,制备出薄的SiGe驰豫缓冲层(虚衬底),表面Ge组份达到0.25,表面粗糙度小于2nm,驰豫度接近100%.在我们制备的SiGe缓冲层上外延了应变补偿SiGe/Si多量子阱结构,并初步研究了其发光特性.

Charged and strange hadron elliptic flow in Cu plus Cu collisions at root s(NN)=62.4 and 200 GeV

We present the results of an elliptic flow, v(2), analysis of Cu + Cu collisions recorded with the solenoidal tracker detector (STAR) at the BNL Relativistic Heavy Ion Collider at root s(NN) = 62.4 and 200 GeV. Elliptic flow as a function of transverse momentum, v(2)(p(T)), is reported for different collision centralities for charged hadrons h(+/-) and strangeness-ontaining hadrons K-S(0), Lambda, Xi, and phi in the midrapidity region vertical bar eta vertical bar < 1.0. Significant reduction in systematic uncertainty of the measurement due to nonflow effects has been achieved by correlating particles at midrapidity, vertical bar eta vertical bar < 1.0, with those at forward rapidity, 2.5 < vertical bar eta vertical bar < 4.0. We also present azimuthal correlations in p + p collisions at root s = 200 GeV to help in estimating nonflow effects. To study the system-size dependence of elliptic flow, we present a detailed comparison with previously published results from Au + Au collisions at root s(NN) = 200 GeV. We observe that v(2)(p(T)) of strange hadrons has similar scaling properties as were first observed in Au + Au collisions, that is, (i) at low transverse momenta, p(T) < 2 GeV/c, v(2) scales with transverse kinetic energy, m(T) - m, and (ii) at intermediate p(T), 2 < p(T) < 4 GeV/c, it scales with the number of constituent quarks, n(q.) We have found that ideal hydrodynamic calculations fail to reproduce the centrality dependence of v(2)(p(T)) for K-S(0) and Lambda. Eccentricity scaled v(2) values, v(2)/epsilon, are larger in more central collisions, suggesting stronger collective flow develops in more central collisions. The comparison with Au + Au collisions, which go further in density, shows that v(2)/epsilon depends on the system size, that is, the number of participants N-part. This indicates that the ideal hydrodynamic limit is not reached in Cu + Cu collisions, presumably because the assumption of thermalization is not attained.

High strength Ni based composite reinforced by solid solution W(Al) obtained by powder metallurgy

The solid-solution-particle reinforced W(Al)-Ni composites were successfully fabricated by using mechanical alloying (MA) and hot-pressing (HP) technique when the content of Ni is between 45 wt% and 55 wt%. Besides, samples of various original component ratio of Al50W50 to Ni have been fabricated, and the corresponding microcomponents and mechanical properties such as microhardness, ultimate tensile strength and elongation were characterized and discussed. The optimum ultimate tensile strength under the experiment conditions is 1868 MPa with elongation of 10.21 % and hardness of 6.62 GPa. X-ray diffraction (XRD), FE-SEM and energy dispersive analysis of X-rays (EDS) were given to analysis the components and morphology of the composite bulk specimens.

一个新的超分子化合物(C_(10)H_(18)N)_6As_2Mo_(18)O_(62)·6CH_3CN·8H_2O的合成、结构及性质

以Dawson型砷钼酸、金刚烷胺为原料 ,合成了一个新的超分子化合物 :(C10 H18N) 6As2 Mo18O62 ·6CH3 CN·8H2 O .通过元素分析 ,IR ,1HNMR等方法对合成的化合物进行了表征 .X射线衍射晶体解析表明 ,金刚烷胺与Dawson型多阴离子以静电力和分子间力 (氢键 )结合 ,并且在新化合物中 ,金刚烷胺及多阴离子结构基本保持不变 .该化合物均具有可逆的光致变色特性 ,基于变色后样品的电子自旋共振 (ESR)谱提出一个可能变色机理 .以该类化合物为修饰剂的本体修饰碳糊电极(APM CPE)对过氧化氢还原有很好的电催化活性.

Synthesis of acyl thiourea derivatives of chitosan and their antimicrobial activities in vitro

Three different acyl thiourea derivatives of chitosan (CS) were synthesized and their structures were characterized by FT-IR spectroscopy and elemental analysis. The antimicrobial behaviors of CS and its derivatives against four species of bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Sarcina) and four crop-threatening pathogenic fungi (Alternaria solani, Fusarium oxysporum f. sp. vasinfectum, Colletotrichum gloeosporioides (Penz.) Saec, and Phyllisticta zingiberi) were investigated. The results indicated that the antimicrobial activities of the acyl thiourea derivatives are much better than that of the parent CS. The minimum value of MIC and MBC of the derivatives against E coli was 15.62 and 62.49 mu g/mL, respectively. All of the acyl thiourea derivatives had a significant inhibitory effect on the fungi in concentrations of 50 - 500 mu g/mL; the maximum inhibitory index was 66.67%. The antifungal activities of the chloracetyl thiourea derivatives of CS are noticeably higher than the acetyl and benzoyl thiourea derivatives. The degree of grafting of the acyl thiourea group in the derivatives was related to antifungal activity; higher substitution resulted in stronger antifungal activity. (c) 2007 Elsevier Ltd. All rights reserved.

O desenvolvimento da cafeicultura no cerrado (1999).

A producao de cafe em coco do cerrado aumentou 83 mil para 728 toneladas, enquanto a brasileira passou de 2,5 para 2,8 milhoes de toneladas, entre 1975 e 1996. nesse periodo, as taxas geometricas de crescimento anual da cultura no cerrado foram de 10,9% para a producao e de 5,6% para a rea colhida, ao passo que noconjunto das demais regioes produtoras do Pais essas taxas foram negativas. Os municipios produtores de cafe do cerrado foram agrupados em cinco regioes: Sul/Cerrado Mineiro; Alto Paranaiba; Nordeste Mineiro; Rondonia e Brasilia. Em 1996, a regiao Sul/Cerrado Mineiro produziu 44,0% do cafe do cerrado e possuia o efetivo de 396,6 milhoes de plantas; Alto Paranaiba contribuiu com 47,1% e contava com o efetivo de 343,3 milhoes de plantas; e a Nordeste Mineiro participou com 4,5% com o efetivo de 62,3 milhoes de plantas. Esta foi dividida em tres sub-regioes: Teofilo Otoni; Capelinha; e Montes Claros. A regiao de Rondonia produziu 1,5% e detinha o efetivo de 28,8 milhoes plantas. A de Brasilia participou com 1,7% da producao e seu efetivo era de 16,6 milhoes de plantas, foi dividida em tres sub-regioes: a do Distrito Federal, a Mineira e Cristalina/Catalao/Silvania. Nova regiao produtora esta surgindo com boas perspectivas no Sudoeste baiano.

Typically Anti-American? The Labour movement, America and Broadcasting in Britain from Beveridge to Pilkington, 1949-62

O'Malley, T. (2007). Typically Anti-American?: The Labour movement, America and Broadcasting in Britain from Beveridge to Pilkington, 1949-62. In J. Wiener and M. Hampton (Eds.), Anglo- American Media Interactions,1850-2000 (pp.234-253). Basingstoke: Palgrave Macmillan. RAE2008

'You say a minority, sir, we say a nation': The Pilkington Committee on Broadcasting (1960-62) and Wales.

Medhurst, J. (2004). 'You say a minority, sir, we say a nation': The Pilkington Committee on Broadcasting (1960-62) and Wales. Welsh History Review. 22(2), pp.109-136. RAE2008

Nomenclature and syntaxonomic notes on some high-rank syntaxa of the European grassland vegetation

We present descriptions of a new order (Ranunculo cortusifolii-Geranietalia reuteri and of a new alliance (Stachyo lusitanicae-Cheirolophion sempervirentis) for the herbaceous fringe communities of Macaronesia and of the southwestern Iberian Peninsula, respectively. A new alliance, the Polygalo mediterraneae-Bromion erecti (mesophilous post-cultural grasslands), was introduced for the Peninsular Italy. We further validate and typify the Armerietalia rumelicae (perennial grasslands supported by nutrient-poor on siliceous bedrocks at altitudes characterized by the submediterranean climate of central-southern Balkan Peninsula), the Securigero-Dasypyrion villosae (lawn and fallow-land tall-grass annual vegetation of Italy), and the Cirsio vallis-demoni-Nardion (acidophilous grasslands on siliceous substrates of the Southern Italy). Nomenclatural issues (validity, legitimacy, synonymy, formal corrections) have been discussed and clarified for the following names: Brachypodio-Brometalia, Bromo pannonici-Festucion csikhegyensis, Corynephoro-Plantaginion radicatae, Heleochloion, Hieracio-Plantaginion radicatae, Nardetea strictae, Nardetalia strictae, Nardo-Callunetea, Nardo-Galion saxatilis, Oligo-Bromion, Paspalo-Heleochloetalia, Plantagini-Corynephorion and Scorzoneret alia villosae. 

Solubility of carbon dioxide, ethane, methane, oxygen, nitrogen, hydrogen, argon, and carbon monoxide in 1-butyl-3-methylimidazolium tetrafluoroborate between temperatures 283 K and 343 K and at pressures close to atmospheric

Experimental values for the solubility of carbon dioxide, ethane, methane, oxygen, nitrogen, hydrogen, argon and carbon monoxide in 1-butyl-3- methylimidazolium tetrafluoroborate, [bmim][BF4] - a room temperature ionic liquid - are reported as a function of temperature between 283 K and 343 K and at pressures close to atmospheric. Carbon dioxide is the most soluble gas with mole fraction solubilities of the order of 10-2. Ethane and methane are one order of magnitude more soluble than the other five gases that have mole fraction solubilities of the order of 10-4. Hydrogen is the less soluble of the gaseous solutes studied. From the variation of solubility, expressed as Henry's law constants, with temperature, the partial molar thermodynamic functions of solvation such as the standard Gibbs energy, the enthalpy, and the entropy are calculated. The precision of the experimental data, considered as the average absolute deviation of the Henry's law constants from appropriate smoothing equations is of 1%. © 2005 Elsevier Ltd. All rights reserved.