Occurrence of spanning of a submarine pipeline with initial embedment

For better understanding the mechanism of the occurrence of pipeline span for a pipeline with initial embedment, physical and numerical methods are adopted in this study. Experimental observations show that there often exist three characteristic phases in the process of the partially embedded pipeline being suspended: (a) local scour around pipe; (b) onset of soil erosion beneath pipe; and (c) complete suspension of pipe. The effects of local scour on the onset of soil erosion beneath the pipe are much less than those of soil seepage failure induced by the pressure drop. Based on the above observations and analyses, the mechanism of the occurrence of pipeline spanning is analyzed numerically in view of soil seepage failure. In the numerical analyses, the current-induced pressure along the soil surface in the vicinity of the pipe (i.e. the pressure drop) is firstly obtained by solving the N-S equations, thereafter the seepage flow in the soil is calculated with the obtained pressure drop as the boundary conditions along the soil surface. Numerical results indicate that the seepage failure (or piping) may occur at the exit of the seepage path when the pressure gradient gets larger than the critical value. The numerical treatment provides a practical tool for evaluating the potentials for the occurrence of pipe span due to the soil seepage failure.

宽光束进入展宽器提高输出脉冲对比度分析

根据分析啁啾脉冲对比度模型,通过光线追迹法详细分析了展宽器对输出脉冲对比度的影响.发现当扩大进入展宽器的入射光束口径,从2mm扩大到40mm时,输出脉冲的对比度提高了近两个数量级;同时发现在相同条件下,当输入脉冲为双曲正割函数时,其输出脉冲的对比度明显好于输入脉冲为高斯脉冲和矩形脉冲的情形。

Physical and thermal properties of P2O5-Al2O3-BaO-La2O3 glasses

The physical and thermal properties Of P2O5-Al2O3-BaO-La2O3 glasses were investigated. The effects of glass compositions on the transition temperature, thermal expansion coefficient, density, hardness and refractive index of glasses were studied. The highest hardness of the glasses is 4143.891 MPa and the lowest thermal expansion coefficient of the glasses is 71.770 x 10(-7)/° C. A phosphate glass with high mechanical strength and good thermal characteristic is obtained.

Enhanced luminescence from transparent Ni2+-doped MgO-Al2O3-SiO2 glass ceramics by Ga2O3 addition

Transparent Ni2+-doped MgO-Al2O3-SiO2 glass ceramics without and with Ga2O3 were synthetized. The precipitation of spinel nanocrystals, which was identified as solid solutions in the glass ceramics, could be favored by Ga2O3 addition and their sizes were about 7.6 nm in diameter. The luminescent intensity of the Ni2+-doped glass ceramics was largely enhanced by Ga2O3 addition which could mainly be caused by increasing of Ni2+ in the octahedral sites and the reduction of the mean frequency of phonon density of states in the spinel nanocrystals of solid solutions. The full width at half maximum (FWHM) of emissions for the glass ceramics with different Ga2O3 content was all more than 200 nm. The emission lifetime increased with the Ga2O3 content and the longest lifetime is about 250 mu s. The Ni2+-doped transparent glass ceramics with Ga2O3 addition have potential application as broadband optical amplifier and laser materials. (C) 2007 Elsevier Ltd. All rights reserved.

火烧、施肥、刈割及其交互作用对草原土壤净氮矿化的影响

我国北方温带草原地处干旱半干旱区，是欧亚大陆草原生物区系的重要组成部分，也是我国重要的畜牧业生产基地。土壤氮素作为陆地植物生长和生态系统初级生产力的主要限制因子之一，了解其矿化和可利用性对各种人为干扰因素的响应，有助于我们充分认识草地退化机理，维持草场生产力并进一步促进畜牧业的可持续发展，为草地恢复、重建和维护提供理论依据。本实验在中国科学院内蒙古草原生态系统定位研究站的多年围封退化样地，分别实施了火烧、施肥、刈割及其交互作用的人为干扰处理，利用原状土野外培养的方法，在两年时间中，研究不同的人为干扰因素（火烧、施肥、刈割及其交互处理）对土壤净氮矿化作用的影响。 火烧显著影响草原的氮循环过程，季节和年际的气候变化参与调节氮循环对火烧处理的响应。多年围封后的初次人工火烧处理显著降低了第一个生长季（2006 年生长季）和其后冬季的土壤净氮矿化速率，但是，火烧处理仅在冬季对土壤无机氮含量产生显著降低作用；2007 年生长季，火烧处理对土壤净氮矿化速率和土壤无机氮含量没有显著作用，但是在个别月份，不同的火烧频率对土壤净氮矿化速率和无机氮含量的影响表现出差异。2006 年生长季，未火烧样地和火烧样地净氮矿化积累量分别为3.07±0.26 g N m-2 和2.18±0.21 g N m-2；冬季，未火烧样地和火烧样地净氮矿化积累量分别为1.18±0.25 g N m-2 和0.51±0.08 g N m-2；2007 年生长季，未火烧样地（BC）、每年火烧样地（B1）和两年一烧样地（B2）净氮矿化积累量分别为1.32±0.21 g N m-2、0.54±0.30 g N m-2 和 0.77±0.24 g N m-2。较为湿润的2006 年生长季的净氮矿化积累量显著高于较为干旱的2007 年生长季，冬季也存在相当丰富的净氮矿化积累量。我们推论，长时间围封后的单次火烧处理对土壤净氮矿化作用的影响可能是短效的，但是年际间气候变化对土壤净氮矿化作用影响显著。 施肥显著提高了土壤的无机氮含量，并且与施肥梯度呈显著正相关关系。施肥对土壤无机氮含量的影响具有累加效应，第一次施肥和第二次施肥后的首次取样，+N5.25 、+N17.5 、+N28.0 三个施肥梯度的样地土壤无机氮含量比未施肥样地分别高出56%、219%、1054%和514%、891%、1811%。施肥处理在2006 年和2007 年对土壤净氮矿化作用都没有显著影响，仅在2007 年的个别月份有一定效果。以上结果说明，无机氮肥的添加可以明显提高土壤中无机氮的含量，满足植物生长的需求，但对于土壤氮转化过程的影响可能还要受其它环境和生物因子的制约。 刈割对土壤无机氮含量和净硝化速率没有显著作用，对土壤净氮矿化速率仅在个别月份表现显著效果。2007 年生长季，未刈割样地和刈割样地净氮矿化积累量分别为1.32±0.21 g N m-2 和1.08±0.35 g N m-2，不存在显著差异。我们推论，长期围封后的单次刈割处理在短期内对生长季的土壤氮动态仅有微弱影响，并且这种效果还可能受水分因素的制约。 火烧、施肥、刈割的交互处理在2007 年生长季对土壤无机氮含量产生显著作用，但是，对土壤净氮矿化速率和净硝化速率没有显著效果，然而，在不同的取样时间，火烧、施肥、刈割的交互处理对土壤无机氮含量、净氮矿化速率和净硝化速率的影响存在显著差异，说明火烧、施肥、刈割的交互处理对土壤无机氮和净氮矿化作用的影响可能受各种环境因子的制约，尤其是在水分相对缺乏的半干旱内蒙古草原，非生物因子和生物因子可能共同影响着土壤中的氮平衡。 本研究初步分析了长期围封后火烧、施肥、刈割及其交互处理对土壤净氮矿化的影响，初步探究了人为干扰和环境气候变化对土壤可利用性氮的调节作用，为科学地进行禁牧、割草、人工养份添加等草原管理提供了数据支持。

发菜类囊体膜的组成及其光合特性的研究

发菜（Nostoc flagelliforme Born. et Flah.）的细胞壁由纤维素、半纤维素、糖脂和蛋白质组成。未经破碎的细胞难以进行各种光合特性的研究。由于纯度较高的发菜类囊体膜制备比较困难，对它的光合机理的研究一直是停留在整体水平上进行。我们采用French Press低温下高压破碎细胞，建立了一种快速简便的制备方法。在提取液中加入一定浓度的Ca2+ （Ca2+既有助于维持类囊体膜的放氧活性又可以使类囊体膜在较低的离心速度下使类囊体膜得到凝集沉淀），从而在较短时间内、在高速离心的情况下得到了纯度较高并具有较高放氧活性的发菜类囊体膜。在此基础上，我们采用改进的Allen（1991）的温和绿胶系统，首次对陆生蓝藻发菜类囊体膜色素蛋白复合体进行了分离，共分离出了11条绿色的色素蛋白复合物条带和两条浅黄色的条带。7条绿色的色素蛋白复合物条带属于PSI组分，4条绿色的蛋白复合物条带属于PSII组分，其中一条浅黄色条带系未被报道过的新的色素蛋白复合物条带，经其光谱性质的分析初步鉴定为类胡萝卜素蛋白复合物，此复合物的分离有助于解释发菜独特的适应荒漠、半荒漠地带高光辐射的特性。 本文还对干燥状态、复水30分钟后和复水生长24小时后的野生发菜及人工培养的发菜藻丝体膜脂及其脂肪酸组成进行了分析。发菜的膜脂由MGDG、MGDG、SQDG和PG组成，其酯酰基部位连接有16:0、16:1、18:0、18:1、18:2和18:3六种脂肪酸。野生发菜中具有高含量的不饱和脂肪酸，其含量可达总脂的73%，其中16:1和18:3分别达到28.9mol%和34.3mol%，远远高于已报道的其它蓝藻，所以我们推测发菜具有极强的抗逆性和其膜脂不饱和程度密切相关。分析不同处理的发菜的膜脂和脂肪酸组成表明，复水对野生发菜的膜脂及其脂肪酸组成没有显著影响，说明发菜的膜脂和脂肪酸组成在干燥状态下能保持很高的稳定性。从野生发菜分离出的藻丝体在25 ℃条件下培养，其膜脂脂肪酸组成发生了显著变化，主要表现为脂肪酸的不饱和程度的大幅度降低，18:3从34.9mol%降低到8.6mol%，16:1从28.9mol%降低到13.9mol%。上述结果表明了发菜具有极强的通过改变其膜脂的脂肪酸组成而适应生存环境的能力。

多路温度信号预处理电路

本发明涉及一种计算机控制的、用于温度传感器信号采集与处理的、具有多个信号采集与处理通道的前端电子设备。用于多测量点温度自动监测与控制系统。一种多路温度信号预处理电路，包括有机箱，多个温度信号输入，基准电压产生电路，其主要特点包括有多个输入电路与其对应的多个温度信号输入、放大电路连接；放大电路连接于多路输出调制电路，多路输出调制电路输出信号；基准电压产生电路与输入电路的输入端连接；输入电路的输出端连接放大电路进而与多路输出调制电路连接或输入电路的输出端连接参比端（冷端）信号处理电路并进而与多路输出调制电路连接，两种连接方式采用跳线器／开关选择设置；计算机控制端连于多路输出调制电路。本发明的有益效果是，适用性强，是一种既可以用于采集处理热电偶信号，也可以用于采集处理热电阻信号的前端设备；集成度高，单机包含通道数多；实行多路同时采集处理，处理速度快。

大蹼铃蟾皮肤白蛋白的分离纯化及抗体制备

通过离子交换层析和凝胶过滤层析,在大蹼铃蟾(Bombina maxima)皮肤中得到其白蛋白(BmA-skin).该蛋白具有较强的胰蛋白酶抑制活性.用0.5mg/只BmA-skin作为免疫源免疫大白兔,经三次免疫后,抽取大白兔血液,分离血清,饱和硫酸氨沉淀,获得抗BmA-skin的多克隆抗体.经ELISA方法测定该抗体与大蹼铃蟾白蛋白发生免疫反应,抗体滴度为1:100000.

Polymerase chain reaction based C4AQ0 and C4BQ0 genotyping: association with systemic lupus erythematosus in southwest Han Chinese

Objective: To investigate the association of complement C4 null genes (C4QO, including C4AQO and C4BQO) and C2 gene with systemic lupus erythematosus (SLE) in southwest Han Chinese; 136 patients with SLE and 174 matched controls were genotyped. Methods: C4 null genes were determined by a polymerase chain reaction (PCR) procedure with sequence specific primers (PCR-SSP). The 2 bp insertion in exon 29, which was previously identified in non-Chinese populations and caused defective C4A genes, was directly typed by sequencing the whole exon 29 using exon specific primers. The exon 6 of complement C2 was also sequenced in both the patients and controls. Results: The frequency of homozygous C4AQO allele was 12.5% (17/136) in patients with SLE compared with 1.1% (2/174) in controls (p<0.001, odds ratio (OR)=12.286, 95% confidence interval (95% CI) 2.786 to 54.170). There was no significant difference for homozygous C4BQO allele between patients with SLE and controls (p=0.699). Patients with the C4AQO gene had an increased risk of acquiring renal disorder, serositis, and anti-dsDNA antibodies compared with those without C4AQO (for renal disorder, p=0.018, OR=8.951, 95% Cl 1.132 to 70.804; for serositis, p=0.011, OR 4.891, 95% CI 1.574 to 15.198; for anti-dsDNA, p=0.004, OR 7.630, 95%Cl 1.636 to 35.584). None of the patients or controls had the 2 bp insertion in exon 29 of the C4 gene. The type I C2 deficiency was not detected in the 3 10 samples. Conclusion: It is suggested that deficiency of C4A (not due to a 2 bp insertion in exon 29), but not C4B or C2, may be a risk factor for acquiring SLE in south west Han Chinese; this results in increased risk of renal disorder, serositis, and anti-dsDNA antibodies in patients with SLE. Racial differences seem to be relevant in susceptibility to SLE.