The energy required to produce materials: constraints on energy-intensity improvements, parameters of demand.

In this paper, we review the energy requirements to make materials on a global scale by focusing on the five construction materials that dominate energy used in material production: steel, cement, paper, plastics and aluminium. We then estimate the possibility of reducing absolute material production energy by half, while doubling production from the present to 2050. The goal therefore is a 75 per cent reduction in energy intensity. Four technology-based strategies are investigated, regardless of cost: (i) widespread application of best available technology (BAT), (ii) BAT to cutting-edge technologies, (iii) aggressive recycling and finally, and (iv) significant improvements in recycling technologies. Taken together, these aggressive strategies could produce impressive gains, of the order of a 50-56 per cent reduction in energy intensity, but this is still short of our goal of a 75 per cent reduction. Ultimately, we face fundamental thermodynamic as well as practical constraints on our ability to improve the energy intensity of material production. A strategy to reduce demand by providing material services with less material (called 'material efficiency') is outlined as an approach to solving this dilemma.

鳜和乌鳢最适温度的研究

研究了体重 47 2— 5 4 0 2g的鳜和 45 0— 5 4 6 2g的乌鳢的最适摄食和生长温度。结果表明 ,鳜的最大摄食率随温度的上升而增大 ,在 2 5— 35℃之间形成“最适温度平台” ;低温 ( 1 0—2 5℃ )时 ,乌鳢的最大摄食率随温度的上升而增加 ,在 2 5— 30℃之间形成“最适温度平台” ,之后随温度的增加而下降 ;鳜的特定生长率随温度的增加而加快 ,在 2 5— 35℃形成“最适温度平台” ;乌鳢的特定生长率受体重和温度的交互影响。

Genomic organization and expression analysis of Toll-like receptor 3 in grass carp (Ctenopharyngodon idella)

Toll-like receptor 3 (TLR3) participates in the innate immune response by recognizing viral pathogens. To investigate grass carp immune system responding to GCRV (grass carp reovirus) infection, the full-length cDNA sequence and genomic organization of grass carp TLR3 (CiTLR3) was identified and characterized. The full-length genome sequence of CiTLR3 is composed of 5668 nucleotides, including five exons and four introns. The full-length of CiTLR3 cDNA is 3681 bp in length and encodes a polypeptide of 904 amino acids with an estimated molecular mass of 102,765 Da and a predicted isoelectric point of 8.35. Analysis of the deduced amino acid sequence indicated that CiTLR3 has four main structural domains, including a signal peptide sequence, 14 LRR (leucine-rich repeat) motifs, a transmembrane region and a TIR (Toll/interleukin-1 receptor) domain. It is most similar to the crucian carp (Carassius auratus) TLR3 amino acid sequence with an identity of 99%. Quantitative RT-PCR analysis showed that CiTLR3 transcripts were significantly up-regulated starting at day 1 and continued through day 7 following GCRV infection (P < 0.05). These data implied that CiTLR3 is involved in antiviral defense, provide molecular and functional information for grass carp TLR3, and implicate their role in mediating immune protection against grass carp viral diseases. (C) 2009 Elsevier Ltd. All rights reserved.

ROLE OF PHOSPHORUS CYCLING IN ALGAL METABOLISM AND ALGAL SUCCESSION IN LAKE DONGHU, CHINA

The role of phosphorus cycling in algal metabolism was studied in a shallow lake, Donghu, in Wuhan using the methods of measuring cell quota C, N and P, and calculating nutrients uptake rate by algal photosynthesis. The mean daily phosphorus uptake rate of phytoplankton varied between 0.04-0.11 and 0.027-0.053 g/m2/d in station I and station II respectively. The turnover time of phosphorus in phytoplankton metabolism ranged from 0.75-5.0 days during 1979-1986. The available P was 0.176 (+/- 0.156) g/m3 (mean +/- SD) in 1982 and 0.591 (+/- 0.24) g/m3 in 1986. The relationship between P/B ratio (Y) and TP (X: mg/l) was described by the following regression equation Y = 1.163 + 0.512logX (r = 0.731, P < 0.001). The dynamics of algal biomass and algal species succession were monitored as the indicators of environmental enrichment. The small-sized algae have replaced the blue-green algae as the dominant species during 1979-1986. The small-sized algae include Merismopedia glauca, Cryptomonas ovata, Cryptomonas erosa, several species Cyclotella. There has been drastic decrease in algal biomass and an obvious increase in P/B ratio. A nutrient competition hypothesis is proposed to explain the reason of the disappearance of blue-green algae bloom. The drastic change in algal size and the results in high P/B ratio (reaching a maximum mean daily ratio of 1.09 in 1986) may suggest a transition of algal species from K-selection to r-selection in Lake Donghu.

Metamorphic InGaAs p-i-n Photodetectors with 1.75 mu m Cut-Off Wavelength Grown on GaAs

Top-illuminated metamorphic InGaAs p-i-n photodetectors (PDs) with 50% cut-off wavelength of 1.75 mu m at room temperature are fabricated on GaAs substrates. The PDs are grown by a solid-source molecular beam epitaxy system. The large lattice mismatch strain is accommodated by growth of a linearly graded buffer layer to create a high quality virtual InP substrate indium content in the metamorphic buffer layer linearly changes from 2% to 60%. The dark current densities are typically 5 x 10(-6) A/cm(2) at 0 V bias and 2.24 x 10(-4) A/cm(2) at a reverse bias of 5 V. At a wavelength of 1.55 mu m, the PDs have an optical responsivity of 0.48 A/W, a linear photoresponse up to 5 mW optical power at -4 V bias. The measured -3 dB bandwidth of a 32 mu m diameter device is 7 GHz. This work proves that InGaAs buffer layers grown by solid source MBE are promising candidates for GaAs-based long wavelength devices.

Passively mode-locking Nd : Gd0.5Y0.5VO4 laser with an In(0.25)Ga(0.75)Aa absorber grown at low temperature

We have demonstrated stable self-starting passive mode locking in a diode-end-pumped Nd:Gd-0.8-Y0.5VO4 laser by using an In0.25Ga0.75As absorber grown at low temperature (LT In0.25Ga0.75As absorber). An In0.25Ga0.75As single-quantum-well absorber, which was grown directly on the GaAs buffer by use of the metal-organic chemical-vapor deposition technique, acts simultaneously as a passive mode-locking device and as an output coupler. Continuous-wave mode-locked pulses were obtained at 1063.5 nm. We achieved a pulse duration of 2.6 ps and an average output power of 2.15 W at a repetition rate of 96.4 MHz. (c) 2005 Optical Society of America.

黄土高原不同降水类型区旱作玉米田土壤干燥化效应与土壤水分承载力模拟研究

在模拟精度验证基础上,应用WinEPIC模型模拟研究了黄土高原不同降水类型区1960～2000年期间不同肥力水平下连作春玉米的产量变化和土壤水分效应。模拟结果表明:(1)洛川、延安、寿阳、榆林连作春玉米产量地区间差异显著,其年平均值分别为4.40、3.75、2.50、1.75t/hm2。施肥增产率和水分利用效率地区间差异均显著,均表现为洛川>延安>寿阳>榆林;同一地区水分利用效率随施肥量的增加而提高,不同地区施肥增产率最大值范围不同。(2)0～7m土层逐月土壤有效含水量地区间差异显著,洛川>延安>寿阳>榆林;同一地区内肥力水平越高,春玉米耗水量越大,逐月土壤有效含水量平均值越低。在春玉米生育期内0～7m土层年度土壤有效水分增减量地区间差异显著,洛川<延安<寿阳<榆林;不同肥力处理间的差异在模拟前期为显著,在模拟后期为不显著。(3)所有地区的春玉米在连作期间0～7m土层土壤湿度剖面分布,在经历了土壤湿度逐年降低、土壤干层逐年加厚的干燥化过程后,均出现了稳定的土壤干层。土壤干燥化速度地区间差异显著,洛川<延安<寿阳<榆林;不同肥力处理间随着施肥水平的提高土壤干燥化速度加快。(4)洛川、延安、寿阳、榆林连作春玉米的...

环戊二烯基轻稀土氯化物的合成及其稳定性的研究

I LnCl_3-LiCl-THF配合物的研究深入地研究了氯化稀土和氯化锂于四氢呋喃溶液中，以不同的摩尔比，在不同条件下的反应。实验结果表明，反应速度随着稀土元素原子半径的减小，LiCl/LnCl_3摩尔比的增大，以及四氢呋喃用量的增加而加快。通过紫外质谱元素分析和X-射线单晶结构分析等证明，随着不同的LiCl/LnCl_3摩尔比和结晶条件的不同，可以得到不同组成的LnCl_3-LiCl-TNF配合物。对(LaCl)(THF)_2(μ_2-Cl)_4[Li(THF)_2]_2和(LaCl)DME(μ_3-Cl)(μ_2-Cl)_5(La·DME)Li(THF)_2晶体的结构分析表明，前者为单斜晶系，P21/C空间群。a=10.542(4), b=32.236(4), c=11.182(6)A °; β=113.50(3) °, V=3484.97 A °~3. Z=4, R=0.0471；后者为三斜晶系，PT空间群，晶胞参数是：a=11.123(3), b=16.564(5), c=8.653(3)A °;α=95.16(3), β=95.63(3), γ=74.71(3) °;V=1527.0A °~3。Z=2，R=0.0303。实验结果还表明，μ_2-和μ_3-氯桥键是LnCl_3-LiCl-THF类配合物中最基本、最重要的配位键，这种键是通过多重键的方式起着稳定分子结构的作用。当进行与有机配体的交换反应时，由于它们的特殊稳定性，能起到阻止轻稀土有机配合物歧化反应的作用。II环戊二烯基轻镧系氯化物的合成及其稳定性的研究对(G_5H_5)_3Ln·THF和LnCl_3·3LiCl-THF (Ln=La, Nd)溶液反应的研究表明，由于μ_2-氯桥键的作用，轻稀土环戊二烯基化合物中环戊二烯基的再分配反应，在0℃或室温下都能迅速进行。通过两者不同的摩尔比反应，经元素分析、红外光谱、~1H NMR和质谱鉴定，方便地合成了C_5H_5 LnCl_2·2LiCl·5THF和(C_5H_5)_2LnCl.LiCl·nTHF (Ln=La, Nd)等配合物。这一结果表明(C_5H_5)_2LnCl.LiCl·nTHF配合物不仅能稳定地存在于THF溶液中，而且能在一定条件下析出结晶。对(C_5H_5)_2LaCl.LiCl·4THF的晶体结构测定表明，该晶体属于正交晶系，Pc2m空间群。a=12.306(4), b=23.056(6), c=26.701(11)A°; V=7575.81A°~3;而(C_5H_5)_2LaCl·LiCl(DME)_2THF晶体则属于六方晶系，a=12.967(4), b=12.967(4), c=24.108(10)A°;V=3510 A°~3。通过(G_5H_5)_3Ln·THF与LnCl_3·3THF (Ln=La, Nd)的反应进一步研究了轻稀土环戊二烯基氯化物的稳定性。经元素分析，红外光谱和晶体结构分析表明合成了[(η~5-C_5H_5)_4La_3Cl_5·3THF]_2·9THF和(C_5H_5)_2 NdCl·THF配合物，前者属于三斜晶系，P1空间群。a=11.690(3), b=11.750(5), c=18.433(6)A°; α=98.75(3), β=95.62(3), γ=118.92(2)°; V=2147.06 A°~3. Z=1, R=0.099。对环戊二烯基轻稀土氯化物的稳定性进行了较详细地讨论。结果表明，THF的用量和化合物的溶解度是影响产物组成的决定因素。当THF的量不足以溶解所生成的产物时，就会歧化成溶解度最大((C_5H_5)_3Ln·THF)和最小(LnCl_3·nTHF)的两种组分。反之，环戊二烯基轻稀土化合物(Ln=La, Nd)中环戊二烯基的再分配反应就能顺利进行。经元素分析和结构测定，在((C_5H_5)_3Nd·THF)和NdCl_3·LiCl-THF溶液的反应体系中，偶然分离得到了[(η~5-C_5H_5)_4Nd_4(μ_4-o)(μ_2-Cl)_8] [Li(DMP)_2THF]_2这一不合常规的化合物，其晶体属于正交晶系，Pna2,空间群a=19.010(7), b=23.231(6), c=14.180(4); V=6261.91 A°~3。Z=4, R=0.054。说明在一定条件下,μ-氧桥键也起到了稳定分子结构的作用。推测了各类环戊二烯基轻稀土氯化物在THF中的合成反应机理,在LiCl存在的反应体系中Ln cl cl Li桥键能与环戊二烯基发生交换反应;在(C_5H_5)_3Ln·THF和LnCl_3·3THF的反应体系中,首先存在着LnCl_3分子之间的互相作用，因而易于形成双核或多核配合物。这类配合物以晶体形式析出时，易于发生结构上的变化，即化合物的结晶形态与溶液中的形态不一定相同。探索了环戊二烯基烯丙基稀土化合物新的合成方法。找到了真空加热脱水制备氯化稀土的最佳条件，其产物纯度在97%以上。通过加入Co_3O_4/Wo_3催化助燃剂的方法，提高了测定稀土有机化合物中碳含量的准确性。

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.

Passively Mode Locked Diode-End-Pumped Nd∶YAG Laser with In0.25 Ga0.75 As as Output Coupler

A novel InGaAs(LT-In0.25 Ga0.75 As) absorber grown by metal organic chemical vapor deposition at low temperature is presented.Using it as well as an output coupler,passive mode locking,which produces pulses as short as several hundred picoseconds for diode-end-pumped Nd∶YAG laser at 1.06μm,is realized.The pulse frequency is 150MHz.