中国能见度长期变化及区域特征分析

为找出中国不同类型观测站点能见度的变化特征及其影响因素,对中国350余个气象观测站29年（1980-2008年）的能见度观测数据进行了分析,并使用人口密度分布数据对观测站点进行分类。结果表明,我国大气能见度在1980年后呈现缓慢下降趋势,整体表现出西高东低的特征,且东部能见度逐年下降趋势显著。能见度下降地区多集中于气候湿润或人口密度较高的地区,且人口越密集,能见度恶化程度越显著,低能见度事件发生频率越高。我国西北,包括内蒙、新疆等人口密度较小、气候较为干燥的地区,其能见度呈现逐年好转的趋势,这可能与我国北方地区沙尘暴次数减少及强度减弱有关。我国华南能见度下降幅度最为显著,人为经济生产活动可能是造成这一现象最主要的原因,而我国华北和华东的能见度变化的区域协同性正逐渐增强,从一个侧面反映了该地区所面临的区域性污染加重的现象。     

中国石化提高采收率技术研究进展与应用

从化学驱油技术、稠油热采技术、注气驱油技术和微生物驱油技术4个方面,对中国石化提高采收率技术的研究进展及应用进行了概述,归纳了各项技术的适用条件、应用结果及存在问题,并讨论了中国石化提高采收率技术规模化应用的方向。研究结果指出：化学驱油技术已成为中国石化提高采收率技术的主体,其中的聚合物驱和二元复合驱已成熟配套,并实现规模化应用。非均相复合驱技术在孤岛中一区聚合物驱后油藏试验成功,预计可提高采收率7.3%。在稠油热采技术中,热化学吞吐、井网加密和普通稠油水驱转热采技术已推广应用,蒸汽驱和热化学蒸汽驱技术仍处于工业化试验阶段。注气驱油技术和微生物采油技术处于现场试验阶段,且均已取得较好的增产效果。中国石化提高采收率技术工业化应用的方向是继续研究适应复杂油藏条件的驱油剂、驱油体系和流度控制技术,并对成熟技术进行组合应用。     

基于OpenCL大规模种群并行遗传算法

为了提高RNA二级结构预测的准确率和加速遗传算法,提出基于OpenCL大规模种群并行遗传算法。通过研究遗传算法中潜在的并行性,以Acer TMP246M-MG-5086为实验平台,先在CPU中实现遗传算法,再使用OpenCL技术在GPU中实现大规模种群并行遗传算法。测试结果表明,并行遗传算法对于RNA二级结构预测的准确率平均提高了约49.88%,使用GPU平均加速比为9.76x。     

成团泛菌产微生物絮凝剂絮凝条件的优化

从活性污泥中筛选得到一株微生物絮凝剂产生菌,经鉴定为成团泛菌,该菌能够利用玉米淀粉废水作为培养基制备微生物絮凝剂,初步纯化的絮凝剂命名为M-127。试验结果表明,M-127对高岭土悬浊液适宜的絮凝条件为：在100mL悬浊液（质量浓度为4g／L）中加入絮凝剂M-127（质量浓度为2g／L）2mL,助凝剂CaCl2（质量浓度为10g／L）2mL,体系pH值7．0,200r／min下搅拌1min,60r／min下搅拌3min,静置10min。在此条件下,M-127对高岭土的絮凝率达到97．09％。     

Changes of immunophysiological characteristics in neonatal calves experimentally challenged with mixture of live bacteria and virus

The aim of the present study was to define efficient immunophysiological parameters in neonatal Holstein calves with an experimentally induced microbial infection. Calves (n = 15) were challenged with classical swine fever virus (LOM strain) and Erysipelothrix insidiosa live vaccine by intravenous injection at 3 wk of age except for control calves (n = 4). The level of total serum IgA was significantly increased at 14 and 19 d post-experimental challenge (DPEC) compared with that in calves at −2 DPEC. At 5 DPEC, relative amounts of bacterial- and viral-specific IgA increased significantly and were sustained until 26 DPEC. In the hematology assay, the neutrophil:lymphocyte ratio (%) in whole blood was significantly decreased at 14 DPEC because of a significant increase in lymphocytes and a coincident decrease in neutrophils. The percentages of CD4⁺ and CD25⁺ T cells were significantly decreased at 14 DPEC and returned to initial levels at 19 DPEC. It is intriguing to note that the level of serum lactoferrin was significantly decreased by the microbial challenge within 1 d. The concentration of haptoglobin was increased within 3 d and gradually decreased in calves after microbial challenge. Our results suggest that 1) bovine serum lactoferrin plays an important role in the innate immune response against microbial infection at an early stage and 2) experimentally induced microbial challenge using porcine live bacterial and viral vaccine in calves could be a good experimental model to evaluate the effect of diet or stress induced by environmental change on the immune responses against microbial infection.     

Effects of silage protein degradability and fermentation acids on metabolizable protein concentration: A meta-analysis of dairy cow production experiments

A meta-analysis was conducted using data from dairy cow production studies to evaluate silage metabolizable protein (MP) concentrations. The data consisted of 397 treatment means in 130 comparisons, in which the effects of silage factors (e.g., date of harvest, wilting, silage additives) were investigated. Within a comparison, a fixed amount of the same concentrate was fed. A prerequisite of data to be included in the analysis was that silage dry matter (DM), crude protein (CP), ammonia N, lactic acid (LA), and total acid (TA) concentrations and digestibility were determined. A smaller data set (n = 248) comprised studies in which silage water-soluble N concentration was also analyzed. The supply of MP was estimated as amino acids absorbed from the small intestine using a model with constant values for ruminal effective protein degradability (EPD) and intestinal digestibility of rumen undegraded protein. Microbial protein was calculated on the basis of digestible carbohydrates and rumen degradable protein (RDP). Alternative models were used to estimate microbial protein formation, assuming the energy values of RDP and TA to be equivalent to 1.00, 0.75, 0.50, 0.25, and 0 times that of digestible carbohydrates. Because EPD values are seldom determined in production trials, they were derived using empirical models that estimate them from other feed components. The goodness of fit of models was compared on the basis of root mean squared error (RMSE) of milk protein yield (MPY) predicted from MP supply (adjusted for random study effect) and Akaike's information criterion. Metabolizable protein supply calculated from basal assumptions predicted MPY precisely within a study (RMSE = 16.2 g/d). Variable contribution of RDP to the energy supply for microbial synthesis influenced the precision of MPY prediction very little, but RMSE for MPY increased markedly when the energy supply of rumen microbes was corrected for TA concentration. Using predicted rather than constant EPD values also increased RMSE of MPY prediction. These observations do not mean that the supply of MP from undegraded feed protein is constant. However, it suggests that our current methods overestimate the range in EPD values and that the techniques have so many inherent technical problems that they can mask the true differences between the feeds. Including new elements in feed protein evaluation models may not improve the precision of production response predictions unless the consequent effects on the supply of other nutrients are taken into account.     

Ultrafast coherent population transfer with a train of weak femtosecond pulse pairs

We investigate ultrafast coherent population transfer in a Λ-type three-level system driven by a train of weak phase-locked pump-Stokes femtosecond pulse pairs, where the pump and Stokes pulses in each pair are applied in counterintuitive order, similar to that in the stimulated Raman adiabatic passage technique. It is shown that due to temporal constructive quantum interference and the subsequent coherent accumulation, complete population transfer can be achieved by a few pulse pairs with suitable interpair and intrapair time delays even if a single pair of pulses in the train is so weak that nearly no population transfer can take place. The method is efficient and robust to moderate variations in the interpair and intrapair time delays, number of pulse pairs, and laser intensity, which is particularly favorable to coherent population transfer in quantum systems with weak oscillator strengths.     

Population transfer in a Λ-type five-level system with equally populated initial and empty final doublet states

We investigate the selective and efficient population transfer in a Λ-type five-level system with equally populated initial and empty final doublet states by time-separated chirped pump and Stokes pulses. We show that it is possible to achieve selective, efficient, and robust population transfer from either of the equally populated initial doublet states to either of the final ground doublet levels by merging stimulated Raman adiabatic passage and chirped adiabatic passage techniques. Moreover, the maximal coherent superpositions between either of the initial doublet states and either of the final doublet states, between the intermediate level and either of the final doublet states, or between the final doublet levels can be achieved by varying the chirp rates and single-photon detuning of the pump and Stokes pulses. This method may have potential applications in quantum coherent control of population dynamics in realistic atomic or molecular systems with equally populated initial and empty final manifolds.     

Performance of a microfluidic microbial fuel cell based on graphite electrodes

A microfluidic microbial fuel cell utilizing the laminar flow to separate the anolyte and catholyte streams based on graphite electrode is proposed. The co-laminar flow of the two streams inside the microchannel is visualized under different flow rates. The effects of the acetate concentration and flow rate on the cell performance are investigated. The results show that the cell performance initially increases and then decreases with increasing influent COD concentration and the anolyte flow rate. The microfluidic microbial fuel cell produces a peak power density of 618 ± 4 mW/m² under the conditions of 1500 mg/L influent COD and an anolyte flow rate of 10 mL/h. The low internal resistance of fuel cell results from elimination of the proton exchange membrane and high surface-to-volume ratio of the microfluidic structure. Moreover, the thickness of biofilm decreases gradually along the flow direction of the microchannel due to the diffusive mixing of the catholyte.