Effect of available food and temperature on the growth and reproduction of Daphnia rosea

Population parameters of Daphnia rosea were studied at various concentrations of Chlorella sp. (0.25, 0.75 and 3.0 mg C l(-1)) at several temperatures (20, 25, 28, and 30 degrees C) in the laboratory. Although there were some differences in the degrees of the effects of the various temperature-food combinations, both food and temperature exerted influences on almost all of the main population parameters of D. rosea. At a water temperature of 28 degrees C, growth and reproduction were reduced, and at the lowest food level (0.25 mgC l(-1)), reproduction failed. D, rosea did not survive at 30 degrees C in spite of abundant food supply, indicating that 30 degrees C is a physiological limit. A positive relationship between body length and brood size was recognized at high and medium food levels. The slope of the regression was the highest at the highest food level and at the lowest temperature (20 degrees C). The low food level exerted a negative influence on the net reproductive rate by lowering the size of egg-bearing females, by decreasing the brood size of each size class, by decreasing the brood number per female, and by increasing the period of empty brood chamber. High water temperature (28 degrees C) also exerted a negative influence on the net reproductive rate in a similar way. For the better understanding of the key factors driving the midsummer dynamics of daphnids in the field, it may be of crucial importance to compare the population parameters of the field populations with experimentally derived values under controlled conditions of food concentration and temperature.

Structural evolution of mechanically alloyed nanocrystalline FeAl intermetallics

Nanostructured FeAl intermetallics were prepared directly by mechanical alloying (MA) in a high-energy planetary ball-mill. The phase transformations and structural changes occurring in the studied material during mechanical alloying were investigated by X-ray diffraction (XRD). Transmission electron microscopy (TEM) was employed to examine the morphology of the powders. Thermal behavior of the milled powders was examined by differential scanning calorimetry (DSC). Disordered Fe(Al) solid solution was formed at the early stage. After 30 h of milling, Fe(Al) solid solution transformed into an ordered FeAl phase. The average crystallite size reduction down to about 12 nm was accompanied by the introduction of the average lattice strain up to 1.7%. The TEM picture showed that the size of milled powders was less than 30 nm. (c) 2007 Elsevier B.V. All rights reserved.

8 mu m strain-compensated quantum cascade laser operating at room temperature

We report on the material growth and device performance characterization of a strain-compensated In0.54Ga0.46As/In0.51Al0.49As quantum cascade laser at lambda similar to 8 mu m. For 2 mu s pulse at a 5 kHz repetition rate, laser action is achieved up to room temperature (30 degrees C). The tuning coefficient d lambda/dT is 1.37 nm K-1 between 83 K and 163 K and 0.60 nm K-1 in the range from 183 K to 303 K. The peak output power is reported to be similar to 11.3 mW per facet at 293 K and the corresponding threshold current density is 5.69 kA cm(-2).

大兴安岭冻土湿地泥炭有机碳矿化对气候变化因子的潜在响应

大兴安岭地区是我国地带性多年冻土和冻土湿地的主要分布区，近30年来，大兴安岭地区整体增温显著，气候变化的幅度加大，加之人类活动的频繁，冻土退化严重，冻土湿地出现了原有湿地萎缩和新生湿地扩张的现象。目前，对大兴安岭多年冻土湿地的研究还非常有限，且定性的研究较多，定量的研究极少，多数研究集中于冻土湿地的分布，冻土与湿地之间的机理探讨及描述多年冻土退化对湿地产生的影响等方面。 本论文通过室内培养实验，分析不同温度和湿度梯度及冻融作用下，大兴安岭不同多年冻土区湿地两层泥炭有机碳的矿化状况。结合回归模型，分析大兴安岭多年冻土湿地泥炭有机碳矿化对不同温度和湿度的响应，探讨在气候预案下，大兴安岭多年冻土湿地对气候变化的潜在响应。获得的主要结论如下： （1）大兴安岭多年冻土湿地存在着碳储层，其不同的冻土湿地区由于自然条件、融深等因素的不同，碳储层的厚度也存在着差异。多年冻土湿地含碳量和含氮量都很高，有机碳含量随剖面深度的增加有降低的趋势，泥炭全氮的含量随剖面深度变化复杂，这与湿地土壤形成的气候条件、微地貌和植被类型等有关。大兴安岭连续多年冻土区泥炭，C/N比要高于不连续多年冻土区湿地，并且有机碳含量与全氮含量存在着很好的耦合关系。 （2）大兴安岭多年冻土湿地泥炭有机碳矿化随温度的升高而升高，在培养温度5-20℃下，总的泥炭有机碳矿化量变化范围为18.55~112.91 mg g-1。虽然连续多年冻土区湿地泥炭有机碳矿化率和矿化量都要高于不连续多年冻土区湿地，但经过温度敏感性系数Q10分析，大兴安岭不连续多年冻土区湿地泥炭矿化对温度的响应更显著。从一元动力学方程分析结果来看，大兴安岭多年冻土湿地泥炭有机碳的矿化对15℃响应更显著。 （3）土壤湿度对大兴安岭多年冻土湿地泥炭有机碳矿化产生一定的影响，泥炭总矿化量出现了先随湿度的增加而增加，达到最适宜值后降低的趋势。从本论文的实验设置来看，大兴安岭多年冻土湿地泥炭有机碳矿化的最适宜湿度为60%WHC。利用二元回归模型很好地反映了湿度对大兴安岭多年冻土湿地泥炭矿化的影响，模型推测大兴安岭连续多年冻土区湿地泥炭有机碳矿化的最优湿度为10-20cm层63%WHC，20-30cm层65%WHC；不连续多年冻土区湿地有机碳矿化的最优湿度为10-20cm层65%WHC，20-30cm层59%WHC。 （4）大兴安岭多年冻土湿地泥炭有机碳矿化受温度和湿度的影响显著，其之间的交互作用同样显著。连续多年冻土区湿地有机碳矿化量要高于不连续多年冻土区湿地，这与其含有更高的有机碳和全氮有关。温度和湿度对泥炭有机碳矿化的影响可以用二元二次回归方程很好的表示（P<0.001），通过回归方程和方差分析，结果表明温度和湿度对大兴安岭多年冻土湿地泥炭有机碳矿化都非常重要。 （5）通过培养实验结果显示，虽然温度仍是影响大兴安岭多年冻土湿地泥炭有机碳矿化的主要因子，但随冻融作用处理次数的增加，冻土湿地泥炭有机碳矿化量和温度敏感性系数Q10值有增加的趋势，这意味着冻融作用对大兴安岭多年冻土湿地泥炭矿化产生了不小的影响。虽然冻融作用对大兴安岭多年冻土湿地的影响并不是很大，但大兴安岭处于寒温带，在气候变暖下，冻融过程的频率将加高，冻融作用对大兴安岭多年冻土湿地的影响不容忽视。 （6）大兴安岭地区近30年气候变化趋势分析表明，年均温增长显著，年降水量变化幅度大。在气候变化下，对于不连续多年冻土区，多年冻土不断的退缩及最终的消失，会使冻土湿地萎缩和消失，原有的典型的贫营养的泥炭藓沼泽湿地可能演化为富营养的苔草沼泽湿地或灌丛沼泽湿地，对于大片连续多年冻土区，冻土湿地的变化更加复杂，出现的湿地类型会更多。通过线性气候预案下的大兴安岭多年冻土湿地泥炭有机碳矿化分析，结果显示大兴安岭多年冻土湿地对气候变化响应显著，特别是对于变湿的环境。气候变化下，大兴安岭多年冻土湿地泥炭存在着潜在的分解，多年冻土湿地与气候变化之间存在着正反馈机制。 目前研究表明，大兴安岭地区对气候变化特别敏感，对大兴安岭冻土湿地的研究既填补了国内研究的空白，又对全球的碳循环研究提供了数据支持，并且加深了对冻土湿地生态过程的了解。

四川蜡瓣花、密花樫木、四川溲疏及云南豆腐柴的化学成分研究

本论文对四川蜡瓣花 (Corylopsis willmottiae Rehd. et Wils.)、密花樫木[Dysoxylum densiflorum (Blume) Miq.]、四川溲疏 (Deutzia setchuenensis Franch)及云南豆腐柴 (Premna yunnanensis W. W. Smith)的化学成分进行了研究。通过色谱分离得到44个化合物。主要基于波谱数据鉴定了它们的结构，其中1个为新化合物。 1．从四川蜡瓣花全株的95%乙醇提取物中共分离鉴定了13个化合物，它们是：1-O-(3-O-甲基没食子酸)-岩白菜素(1)、11-O-没食子酰基岩白菜素(2)、 11-O-紫丁香基岩白菜素(3) 、岩白菜素(4)、4-O-没食子酰基岩白菜素(5) 、4,11-O-二没食子酰基岩白菜素 (6)[14]、β-谷甾醇 (7)、acetyl aleuritolic acid (8)、(-)-表没食子儿茶素没食子酸酯(9)、对羟基苯甲酮 (10)、 11-香豆酸酰岩白菜素 (11)[19]、丁香酸 (12)和没食子酸 (13)。其中1为新化合物。 2．从密花樫木根的95%乙醇提取物中共分离纯化了13个化合物，它们是：β-白檀酮(14)、richenone (15)、β-谷甾醇 (7)、cabraleadiol (16)、β-香树脂醇 (17)、龙脑香醇酮 (18)、cabraleadiol monoacetate (19)、cabraleone (20)、3β-hydroxy-5 -pregnen-20-one (21)、3β-hydroxy-5α-pregnan-20-one (22)、cabraleahydroxylactone (23)、川楝子甾醇B (24)、表儿茶素 (25)。 3．从四川溲疏全株95%乙醇提取物中共分离11个化合物，鉴定了其中的9个化合物。它们是：β-谷甾醇 (7)、白桦酯醇(26)、齐墩果酸(27)、hydrangetin (28)、肉桂酸 (29)，齐墩果酸-3-O-β-D-吡喃葡萄糖醛酸苷(30)、β-胡萝卜苷 (31)、齐墩果酸-3-O-（β-D-吡喃葡萄糖醛酸-6-正丁酯）(32)、齐墩果酸-3-O-β-D-吡喃葡萄糖醛酸-28-O-β-D-吡喃葡萄糖苷 (33)。 4．从云南豆腐柴95%乙醇提取物中分离得到12个化合物，分别为白桦脂醇 (25)、7-羟基黄烷酮 (34)、松属素 (35)、2’,4’-羟基查儿酮 (36)、高良姜素-3-甲醚 (37) 、高良姜素-3,7-二甲醚 (38)、异甘草素-4-甲醚 (39)、豆蔻明 (40)、乔松酮 (41)、异甘草素 (42)、arjunolic acid (43)、槲皮素3-O-β-D-木糖苷(44)。 5．综述了1976年以来樫木属植物化学成分和活性研究的概况。 Phytochemical investigation on Corylopsis willmottiae, Dysoxylum densiflorum, Deutzia setchuenensis, and Premna yunnanensis, led to the isolation of 44 compounds, 1 of which was new one. 1. One new compound was isolated from 95% ehanolic extrat of the whole plants of C. willmottiae, identified as 11-O-(3-O-methylgalloyl)-bergenin (1). The twelve known compounds isolated were 11-O-galloylbergenin (2), 11-O-syringylbergenin (3), bergenin (4), 4-O-galloylbergenin (5), 4,11-di-O-galloylbergenin (6), β-sitosterol (7), acetyl aleuritolic acid (8), (-)-epigallocatechin 3-O-gallate (9), 1-(4-hydroxyphenyl) ethanone (10), 11-O-coumaroylbergenin (11), syringic acid (12), gallic acid (13). 2. Thirteen compounds were isolated from 95% ethanol extract from the roots of D. densiflorum and identified as β-amyrenone (14), richenone (15), β-sitosterol (7), cabraleadiol (16), β-amyrin (17), hydroxydammarenone-Ⅱ (18), cabraleadiol monoacetate (19), cabraleone (20), 3β-hydroxy-5-pregnen-20-one (21), 3β-hydroxy-5α-pregnan-20-one (22), cabraleahydroxylactone (23), toosendansterol B (24) and (-)-epicatechin (25). 3. Eleven compounds were isolated from ethanol extract of D. Setchuenensis. Nine were identified as β-sitosterol (7), betulin (26), oleanolic acid (27), hydrangetin (28), cinnamic acid (29), oleanolic acid 3-O-β-D-glucuronopyranoside (30), β-daucosterol (31), oleanolic acid 3-O-β-D-glucuronopyranoside-6-O-butyl ester）(32), oleanolic acid 3-O-β-D-glucuronopyranosyl-28-3-O-β-D-glucopyranoside (33). 4. Twelve compounds were isolated from ethanol extract of P. yunnanensis and identified as betulin (26), 7-hydroxyflavanone (34), pinocembrin (35), 2’,4’-dihydroxychalcone (36), galangin 3-methyl ether (37), galangin 3,7-dimethyl ether (38), isoliquiritigenin 4-methyl ether (39), cardamonin (40), pinostrobin (41), isoliquiritigenin (42), arjunolic acid (43), quercetin 3-O-β-D-lyxosopyranoside (44). 5. Chemical constituents and biological activities of the genus Dysoxylum (Meliaceae) were reviewed during 1976-2009.

用~(12)C离子模拟质子引起的单粒子效应

在理论分析的基础上 ,提出了一种利用兰州重离子加速器提供的高能 12 C离子模拟质子引起单粒子效应的途径 .在保证核反应机制是引起单粒子效应主要机制的前提下 ,用高能 12 C离子可以模拟质子在功率金属 -氧化物 -半导体场效应晶体管中引起的单粒子烧毁以及单粒子栅极击穿 ,获得质子单粒子效应的饱和截面 ,定性研究质子单粒子效应的角度效应 ,还可以作为高能质子单粒子效应实验前的预备实验 .该方法拓展了兰州重离子加速器加速的轻的重离子在单粒子效应实验研究方面的应用 ,对现阶段国内开展质子单粒子效应实验研究具有重要意义

C离子注入Si中Si_(1-x)C_x合金的形成及其稳定性

利用离子注入和高温退火的方法在Si中生长了C含量为0.6%~1.0%的Si1?xCx合金, 研究了不同注入剂量下Si1?xCx合金的形成及其在退火过程中的稳定性. 如果注入剂量小于引起Si非晶化的剂量, 850℃退火后, 注入产生的损伤缺陷容易与C原子结合形成缺陷团簇, 难于形成Si1?xCx合金. 随着注入C离子剂量的增大, 注入产生的损伤增强, 容易形成Si1?xCx合金, 但注入的剂量增大到一定程度, Si1?xCx合金的应变将趋于饱和, 即只有部分C原子进入晶格位置形成合金相. Si1?xCx合金一旦形成, 在950℃仍比较稳定, 而温度高于1 000℃, 合金的应力将部分释放. 随着合金中C原子浓度的升高, 合金的稳定性变差.

脱落酸对UV-C胁迫下小麦幼苗光合特性及抗氧化酶活性的影响

研究了UV-C辐射下短期和长期脱落酸(ABA)处理对小麦幼苗CO2同化作用、羧化效率、光合CO2响应以及抗氧化酶活性等的影响.结果表明,在无UV-C辐射情况下,短期和长期ABA处理能提高光合速率,比对照增加14·69%和20·46%,降低气孔导度,比对照降低14·74%和17·31%,但对胞间CO2浓度和羧化效率影响不大.当受到UV-C辐射时,光合速率、羧化效率、气孔导度和胞间CO2浓度逐渐降低.长期ABA处理变化最小,其次为ABA短期处理,对照降低最大.ABA处理能够提高小麦光合对CO2的响应,UV-C辐射抑制光合对CO2的响应.ABA处理能够提高小麦抗氧化酶(CAT、SOD、POD)活性而降低MDA含量.在UV-C辐射下,CAT活性先升高随后降低,在辐射处理1h时活性达最大值,ABA处理的SOD和POD活性先升高后降低,且ABA长期处理比短期处理增加明显,对照则逐渐降低.ABA处理可能通过提高小麦CO2同化作用和抗氧化酶活性增强对UV-C胁迫的抗性,且ABA长期处理比短期处理效果更明显.

增强UV-C辐射作用下小麦和豌豆幼苗光合响应及其相对抗性

以小麦和豌豆为材料,研究了UV-C辐射(波长<280nm)对叶片光合特性及抗氧化酶活性的影响.结果表明:UV-C辐射增强,可使豌豆叶片光合速率减弱,气孔导度、胞间CO2浓度、蒸腾速率和羧化效率明显降低,而对小麦叶片上述各项指标的影响则是先增加、后降低;在UV-C辐射下,豌豆的CO2补偿点逐渐升高,而小麦的CO2补偿点先降低、后升高.UV-C辐射除了使豌豆的POD活性和小麦的SOD活性逐渐降低外,其他抗氧化酶活性则呈先升高、后降低的变化趋势.小麦对短时间UV-C辐射的抗性比豌豆强,但随着UV-C辐射时间的延长,小麦和豌豆的抗氧化酶活性均降低,光合作用减弱.

蛭弧菌J26发酵生产维生素C前体产物的鉴定

采用有机溶剂沉淀方法去除J26发酵液中杂蛋白，通过离子交换、活性炭吸附去除发酵液中杂质，最后蒸发浓缩获得无色透明结晶。通过对所获晶体的红外光谱分析、熔点测定、纸层析鉴定，证明所获晶体确为维生素C前体2－酮基－L－古龙酸（2－KGA）。

Phenolphthalein immobilized membrane for an optical pH sensor

A phenolphthalein immobilized cellulose membrane for an optical pH sensor was described. The phenolphthalein was first reacted with the formaldehyde to produce a series of prepolymers with many hydroxymethyl groups. In this paper, the prepolymers was abbreviated to phenolphthalein-formaldehyde (PPF). Then the PPF was covalently immobilized to the diacetylcellulose membrane via hydroxymethyl groups. Finally the membrane was hydrolyzed in the 0.1 M NaOH solution for 24 h to reduce the response time. Advantageous features of the pH-sensitive membrane include (a) a large dynamic range from pH 8.0 to 12.50, or even broader, (b) rapid response time (2-30 s), (c) easy of fabrication, and (d) a promising material for determination of high pH values. The immobilized PPF has a broader dynamic range from 8.0 to 12.50 than the free phenolphthalein from pH 8.0 to 11.0, and this was due to the newly produced methylenes in our investigation.

A phenomenological study of the structural relaxation of an inorganic glass (Li(2)O2SiO(2))

The structural relaxation process of an inorganic glass (Li(2)O2SiO(2)) has been studied by differential scanning calorimetry. The sample is subjected to different thermal ageing histories with isothermal stages at an ageing temperature of T-g - 30 degrees C for different ageing times and at an ageing time of 16 h for different ageing temperatures. A four-parameter Tool-Narayanaswamy-Moynihan (TNM) model, is applied to simulate the normalized specific-heat curves measured. The ageing-temperature and ageing-time dependence of the structural relaxation parameters in the TNM model is obtained. (C) 1998 Elsevier Science S.A. All rights reserved.

Gas transport property of homo- and copolyimides from isomeric thiaphthalic dianhydride and oxydianiline

Gas transport properties of home- and copolyimides prepared from 3,3',4,4'- and 2,2',3,3'-thiaphthalic dianhydride (p-TDPA and m-TDPA, respectively) with 4,4-oxydianiline (ODA) were investigated. The fractional free volume of m-TDPA-ODA is larger than that of p-TDPA-ODA, and the chain segmental mobility of the former is lower than that of the latter. The permeability coefficients of m-TDPA-ODA to H-2, CO2, and O-2 are more increased by 48, 69 and 75%, at 30 degrees C and 10 atm, respectively, than those of p-TDPA-ODA; but the permselectivities of m-TDPA-ODA for H-2, CO2, and O-2 toward N-2 are more decreased by 33, 77, and 26%, respectively, than those of p-TDPA-ODA. The permeability coefficients and the diffusion coefficients of the copolyimides can be described by the following equations: log P = Phi(p) log P-p + Phi(m), log P-m and log D-a = D-a = Phi(p) log(D-alpha)(p) + Phi(m) log(D-a)(m), respectively. The variation of the permselectivity is controlled predominantly by diffusivity selectivity. These observations are interpreted in terms of variations in the fractional free volume of polyimides. (C) 1997 John Wiley & Sons, Inc.

Kinetics of the polymerization of isoprene with isopropoxyneodymium dichloride/triethylaluminium binary lanthanide catalyst system

The kinetics of the polymerization of isoprene with the heterogeneous rare earth catalyst system isopropoxyneodymium dichloride/triethylaluminium (Nd(OPri)Cl-2-AlEt(3)) was examined in a specially designed dilatometer. The rate of polymerization is expressed as R(p) approximate to -d[M]/dt = k'(p)[Nd](1.40)[M]. The main kinetical parameters such as the concentration of active propagating chain, the efficiency of lanthanide catalyst used (ELCU), the absolute rate constant of propagation as well as the average life time of growing chains, were determined at 30 degrees C, 40 degrees C, 45 degrees C and 50 degrees C.

Effects of Irradiance and Temperature on the Photosynthesis and Vegetative Propagation of Caulerpa serrulata

The photosynthetic oxygen evolution of Caulerpa serrulata was determined with oxygen electrodes. The effects of light and temperature on the growth and regeneration of fragmented C. serrulata thalli were analyzed. The regenerating rate and establishment of different sizes and portions of C. serrulata were studied. The results showed that the light saturation point of C. serrulata was 200 mu mol photons/m(2) per s and the optimum growth temperature was 25-30 degrees C. Under these conditions, the maximum photosynthetic oxygen evolution rate was 15.1 +/- 0.29 mg O-2/mg Chl a/h, the growth rate and elongation rate reached the highest values, 4.67 +/- 0.09 mg FW/d and 0.78 +/- 0.01 mm/d, respectively. The fragmented C. serrulata thalli was regenerated at 20-35 degrees C and survived at 15 degrees C and 200 mu mol photons/m(2) per s. A different survival rate was detected according to fragment size. All of these results indicated that C. serrulata was a candidate to become an invasive species if introduced into a new place. Therefore, we should pay more attention to C. serrulata for its potential threat to marine ecosystem when it is sold for aquarium use.