Hydrothermal processes of Alpine Tundra Lakes, Beiluhe Basin, Qinghai-Tibet Plateau

Most of the alpine tundra lakes, of average size 8,500 m², are widely spread in the Beiluhe Basin on the Qing-Tibet Plateau, where ice-rich permafrost exists. Approximately 70% of the lakes are elliptical in shape and 15% are elongated. About 80% of the lakes are unfrozen to the bottom throughout the year while a larger portion of it, about 60%, may be underlain by taliks that penetrate permafrost. The BLH-A Lake, a representative lake with 2-m deep water in the region, has been observed for about four years (from 2006 to 2009). Ice starts to cover on the lake-surface after mid-October, and its thickness increases to 60 to 70 cm by the end of cold season. The ice cover then starts to melt in later April and melts completely around mid-May. The lake-surface temperatures change sinusoidally with the air temperatures, but lagging about half a month. The water warms with the increase of the water depth, and the maximum annual temperature appears at depth of 1.5 m with a value of 14.3 °C on July 30, 2007. The lake-bottom temperatures are not isothermal at different depths for most time of a year. It may be related to the variable climate, little snow, and intensive solar radiation. The mean annual lake-bottom temperatures are about 5.5 °C in the deep pool with 2 m deep water and 4.3 °C in the shallow nearshore zone with 1 m deep water. The warm lake-bottom causes considerable disturbance to the permafrost. Surveyed data show that there is no permafrost under the lake when the mean annual lake-bottom temperature is over 5 °C.     

基于小波变换与反锐化掩模的图像对比度增强

针对传统空间域图像对比度增强算法存在灰度级空间分配不合理和噪声敏感的问题,基于图像的局部细节信息分析,提出了一种新的基于小波变换和反锐化掩模(UM)的图像对比度增强算法.该算法以小波变换作为工具,运用反锐化掩模的思想,计算出代表局部细节信息且同时考虑了图像中的噪声信息的统计量,然后将这一新的统计量作为重新分配灰度级空间...     

4种萘酰亚胺类荧光增白剂的合成及性能研究

以4-溴-1,8-萘二甲酸酐为原料,与端基含有氨基的伯胺(如苯胺)和自制1.0G PAMAM发生酰胺化反应得到4-溴-1,8-萘酰亚胺,将其C4-位的溴被甲氧基和乙氧基取代进而得到4种具有强烈荧光性能的萘酰亚胺类荧光增白剂.经FT-IR表征其结构,用UV-vis、荧光光谱等手段研究了它们在水溶液中光物理化学性质.结果表...     

加氢精制再生催化剂的合理使用

再生催化剂的孔体积和比表面积与新鲜催化剂相比有所降低,且残存少量的硫和炭,为了合理利用已达到使用寿命的加氢精制再生催化剂,在分析加氢精制再生催化剂特点的基础上,提出了再生催化剂降级使用的技术方案,并介绍了在再生催化剂装填和硫化过程中,与新鲜催化剂的差别及应该注意的事项。再生催化剂在降低使用后的硫化剂使用量可按照理论需硫量的0．9～1．0倍调整。     

石油科学研究常用方法及其若干案例

文章依据宏观科学方法论对石油科技工作中常用的一些思维方式、思想方法和工作方法进行了总结归纳,强调了在唯物辩证法指导下运用"思维的基本方法",即:归纳与演绎法、分析与综合法、灵感与机遇法、抽象思维与形象思维法、逆向思维法等方法系统分析研究问题的重要性,并介绍了"思维的基本法"中的"分析与综合法"和"逆向思维法"、"抽象与形象思维法"在油气勘探、化工产品研究和开发中的应用实例,如塔里木盆地的再认识、华北断陷盆地洼槽聚油新理论的形成和发展等,无不闪耀着思维升华的光辉。     

TD-LTE RAN承载技术方案分析

通过分析TD-LTE RAN承载需求,结合中国移动的TD网络建设现状,对中国移动的TD-LTE RAN承载技术方案进行描述和分析对比。     

Multisim在非正弦波振荡电路中的应用

通过“三角波振荡电路”的创建及观测实例,表明了Multisim仿真软件在电子线路中课堂教学的应用优势.     

Use of Caenorhabditis elegans for preselecting Lactobacillus isolates to control Salmonella Typhimurium

Host-specific probiotics have been used to control enteric pathogens, including foodborne pathogens, in food animal production. However, evaluation of the efficacy of these probiotics requires costly in vivo assays in the target animal. The nematode Caenorhabditis elegans has been used for prescreening of antimicrobial agents and for studies of host-pathogen interactions. In the present study, 17 Lactobacillus isolates from chicken and pig intestines were tested with C. elegans, and the ability of these isolates to prevent death from Salmonella infection was variable. Two Lactobacillus isolates (S64, which gave full protection, and CL11, which gave no protection) were further studied. Both isolates exhibited a similar colonization profile in the C. elegans intestine. Although different culture fractions of CL11 were not protective, both live and heat-killed S64 cells provided full or partial protection of C. elegans from death caused by Salmonella infection. In contrast, different culture fractions from both isolates had similar effects on the colonization of the nematode intestine by Salmonella Typhimurium DT104. Our preliminary results from a pig performance trial revealed a correlation between the degree of protection in the C. elegans survival assay and the performance of 35-day-old weaned piglets that were treated with the same Lactobacillus isolates, suggesting that C. elegans can be used as a laboratory animal model for preselecting probiotics for control of Salmonella infections.     

Preparation and characterization of novel yellow pigments: hollow TiO<Subscript>2</Subscript> spheres doped with cerium

Ce-doped TiO₂ hollow yellow pigment particles were synthesized by coupling template-directed method with Pechini sol–gel process. The effects of water content, ethanol/acetonitrile volume ratio and tetrabutyl orthotitanate concentration, on the fabrication of PS@TiO₂ composite particles (the key intermediate product) were investigated and the final pigments were characterized in detail by X-ray diffraction, transmission electron microscopy, scanning electron microscope, X-ray photoelectron spectroscopy, and UV–vis diffuse reflection. The results show that the optimal water content and ethanol/acetonitrile volume ratio are 0.09 mol dm⁻³ and 3:1, respectively, for the construction of neat PS@TiO₂ core–shell structure without secondary titania particles, and that the damage of hollow spheres can be avoided by increasing the shell thickness, and that the prepared hollow spheres were well-crystallised with anatase phase TiO₂ and cubic CeO₂. Owing to the intrinsic yellow color and lower density, the as-prepared hollow pigments can be expected to be used for color electronic paper display.