CO_2激光器泵浦CH_3OH产生THz激光的理论分析

以激光速率方程理论为基础出发点,搭建出三能级系统模型,从而对光泵的CH3OH分子产生THz激光机理和动力学过程做了理论分析。结合实验参量,使用CO2激光器输出的9P(36)支线泵浦CH3OH气体分子产生118.8μm的THz激光,并在工作气压为10 Pa,温度为常温(20℃)下,分析了三能级粒子数密度变化情况及输出功率波形特征,以及改变缓冲气压、腔内温度和输出镜反射率的情况下,对激光输出功率的影响。结果表明,理论计算结果能较好地反映光泵产生THz激光的过程。     

百合花挥发油的提取及抗氧化活性的研究

采用水蒸气蒸馏法提取干百合花挥发油,并测定了挥发油的抗氧化能力。结果显示:百合花挥发油的提取率为0.018 5%,在0.350~7.00mg/m L浓度范围内对·OH的清除能力为3.13%~73.65%;在0.20~1.20mg/m L浓度范围内对DPPH·的清除能力为39.13%~84.06%;通过与VC作为清除剂进行对比,以IC50作为参数,其对·OH的清除能力弱于VC,而对DPPH·的清除能力与VC相当。可见,百合花挥发油具有抗氧化活性,一定的清除自由基能力,可作为一种挥发油提取来源。     

Millennial climate changes since MIS 3 revealed by element records in deep-sea sediments from northern South China Sea

High resolution elemental MD05-2903 from the northern South records in core China Sea were obtained from XRF scanning and grain size and mineral component analyses. The K/Ti curve reveals climate changes since MIS 3 on a millennial scale, representing one of the best such records so far from deep-sea sediments of the South China Sea. When compared our K/Ti record with other climate records from high latitude ice cores and from East Asia stalagmites, variations in the K/Ti record show some typical saw-shaped features of rapid climate changes in the Northern Hemisphere. Grain size analysis reveals a close relationship between variations in K/Ti and in the fine end-member grain size. XRD analysis confirms that high K/Ti layers were dominated by K-rich weathering minerals, especially illite, while low K/Ti layers contain low illite but high abundance of Ti-rich heavy minerals. Therefore, the K/Ti record reflects changes in the input and deposition of fine weathering minerals and heavy minerals in the northern South China Sea region during stadials and interstadials. These elemental changes were largely con- trolled by variations in rainfall, erosion, and fluvial trans- portation induced by East Asia Monsoon.     

Gold nanorod translocation through a solid-state nanopore

Recently, nanopores have been used in an essential technique for detecting single molecule with high sensitivity. The initial application of nanopores to DNA and RNA sequencing has been expanded to sensing pro- teins and nanoparticles, including Bovine serum albumin, silica nanoparticles, polystyrene beads, and others. In our study, for the first time, a positively charged gold nanorod was investigated using a solid-state nanopore device. Various gold nanorods passed through the nanopore with different current blockages and duration times, providing a measurement of the nanorod diameter, length, and charge. Our findings indicate that nanopore sensing might be a new method for characterizing the size, shape, and charge of nanoparticles.     

Combinational electroporation and transplantation approach to studying gene functions in avian embryos

Gene transfection is an indispensable approach for studying gene function since it provides important information on gain- and/or loss-of-function. Chick embryos are also extensively employed for studying bio- logical function since they are easily accessible and can be maintained alive after manipulation. The combination of both techniques presents a powerful approach to under- standing how genes regulate embryo development. Fur- thermore, combining these approaches with tissue transplant techniques make even more attractive for elu- cidate gene function. Electroporation, employing parallelly fashioned electrodes, has been widely used in chick embryos. However, experimenters have been frustrated by unsuccessfully transfection in some embryonic tissue of interest because the electrodes were improperly positioned.We presently demonstrated the different patterns of orga- nizing and positioning the electrodes, in combination with tissue transplantation, to efficiently and specifically trans- fect the chick embryonic head, trunk neural tube, heart tube, somites and neural crest cells with the GFP reporter gene.     

Effect of ytterbium on sodium current and its kinetics in rat hippocampal neurons

This study addressed the effects of Yb3＋ on voltage-gated sodium currents in rat hippocampal neurons using the whole-cell patch-clamp technique. Voltage-clamp recordings in single neurons were filtered and stored in a computer. Yb3＋ increased the amplitude of sodium currents in a concentration-dependent and voltage-dependent man- ner. The 50 % enhancement concentration of Yb3＋ on sodium currents was about 8.97 μmol/L, which was dif- ferent from the inhibitory effects of Yb3＋ on potassium current. The analysis on the activation and inactivation kinetics of Na＋ current showed that 100 μmol/L Yb3＋ did not change the process of activation and inactivation. In addition, the times reaching the peak of current （t） and inactivated time constant （τ） were voltage dependent. 100 μmol/L Yb3＋ significantly prolonged the time to peak at -70 and -80 mV. The effect disappeared at the positive direction of -70 mV. Furthermore, Yb3＋ decreased r val- ues to more positive values than -80 mV. In total, Yb3＋ did not change the process of activation, but impelled inacti- vated process. Yb3＋ mainly increased the Na＋ current through changing its conductance. It might be one of the mechanisms that Yb3＋ affected the hippocampal neurons.     

Genetically engineered organisms for bioremediation of pollutants in contaminated sites

Environmental pollution is a major problem which affects biodiversity, public health and ecosystems worldwide. This issue cannot currently be solved using conventional technology because these treatments are expensive, ineffective and time consuming. Conventional methods focus unduly on the separation, rather than the destruction of contaminants. The use of genetically engi- neered organisms for bioremediation would be an envi- ronmentally-friendly and cost-effective alternative for the management and remediation of pollutants in contaminated sites. Different types of genetically engineered microbes have been developed through recombinant DNA and RNA technologies, these have been utilized for the removal of heavy metals and toxic substances from contaminated sites. Transgenic plants can also mobilize or degrade chlorinated solvent, xenobiotic compounds, explosives and phenolic substances. A symbiotic relationship between genetic engineered microbes and transgenic plants can enhance the effectiveness of bioremediation of contaminated sites. This review examines recent developments in the use of genetically engineered microbes and transgenic plants forthe bioremediation of contaminated sites. This review will also identify the environmental factors which influence bioremediation by genetically engineered microbes and transgenic plants as well as suggesting future directions for research in these areas.     

Retrievals of atmospheric boundary layer temperature and moisture profiles by using Atmospheric Emitted Radiance Interferometer （AERI） measurements in Shouxian

The ground-based Atmospheric Emitted Radi- ance Interferometer （AERI） was deployed in Shouxian, China in 2008 to measure down-welling infrared radiances with high resolution. Based on AERI observations, we propose a new method for retrieving vertical temperature and water vapor profiles in the planetary boundary layer （PBL）. The method exclusively uses NCEP-2, a global reanalysis data as a first-guess profile in an iterative recursive algorithm. The PBL profiles of temperature and moisture under clear sky conditions in Shouxian have been retrieved using this new method. Compared with coinci- dent radiosonde measurements, we find that AERI is able to obtain more accurate temperature and water vapor pro- files in the PBL. The retrieval results with high temporal resolution can be used to monitor the PBL stability and evolution.     

大强度运动对青年男子淋巴细胞凋亡的影响

设计训练组(T组,14名男性田径运动员)和对照组(C组,14名男性普通大学生)均完成一次大强度运动,并于运动前、运动后即刻以及运动后12h取血液淋巴细胞测定淋巴细胞计数、凋亡率、羟自由基(·OH)和8-氧鸟嘌呤(8-oxodG)含量,对比运动员和普通大学生在一次大强度运动前后淋巴细胞DNA损伤的变化,探讨长期运动训练对淋巴细胞凋亡的影响及其可能机制.结果显示,运动后即刻:组内前后比较,两组所有指标均显著性升高(P<0.05或P<0.01);组间比较,T组指标变化的幅度均低于C组(P<0.01).运动后12h:组内前后比较,C组淋巴细胞凋亡率和8-oxodG含量升高(P<0.01),淋巴细胞计数降低(P<0.01),·OH含量恢复(P>0.05),T组8-oxodG含量升高(P<0.05),其他指标均恢复至运动前水平;组间比较,T组8-oxodG含量升高幅度明显低于C组(P<0.01).以上结果表明:一次大强度运动诱导淋巴细胞自由基产生增多并造成DNA氧化损伤,细胞凋亡增加;长期运动训练则可降低淋巴细胞DNA氧化损伤和细胞凋亡并加速凋亡恢复,防止运动应激后淋巴细胞数量的减少.     

An efficient non-iterative algorithm to estimate the apparent diffusion coefficient of water molecules in the magnetic resonance diffusion imaging experiments

Many studies have shown that the magnetic resonance signal decay with an extend range of diffusion weighting(b-factor)is a bi-exponential attenuation in the diffusion-weighted magnetic resonance imaging experiments in vivo.Based on this feature and the two-compartmental model,we propose a twice-linear-fitting(TLF)algorithm to estimate the apparent diffusion coefficient(ADC)of the water molecules instead of the commonly used iterative Levenberg–Marquardt(LM)method.The TLF algorithm consists of two liner fitting steps to estimate the fast and the slow apparent diffusion coefficients and their sizes,respectively.It is unnecessary to guess the initial values in the whole fitting process.The time consumption of the TLF algorithm is much less than that of the iterative LM method.Moreover,the TLF algorithm may avoid the extraneous solutions,which often deteriorates the results of the LM method.Compared with the iterative fitting method,the TLF algorithm is a reliable and timeefficient approach to estimate the ADC of water molecules in vivo in magnetic resonance diffusion-weighted imaging experiments.