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.     

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.     

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.     

Computational diffusion kinetics and its applications in study and design of rare metallic materials

Computational diffusion kinetics(CDK),with a spirit of and being coupled with the computational thermodynamics(CT,or called as the CALPHAD technique),plays increasingly important role in the alloy design/optimization and microstructure control during the processing of advanced metallic materials.This paper is to highlight recent progress of CDK in research with great focus on novel Ti and Zr alloys,which was largely performed in the authors’group.It ends with one representative example of the applications of CDK,coupled with CT,quantitative phase field,and three-dimensional(3D)statistical calculation,in designing the heattreatment schedule for the dual phase(αβ)Ti–6Al–4V alloys.     

Monitoring dynamic changes of global land cover types:fluctuations of major lakes in China every 8 days during 2000–2010

Remote sensing images can be used to delineate variations in the area of lakes and to assess the influence of environmental changes and human activities.However,because lakes are dynamic,results obtained from individual images acquired on a single date are not representative and do not accurately reflect ongoing changes.In this study,we used 8-day moderate resolution imaging spectroradiometer(MODIS)composite data from 2000 to2010 to map water surface changes over 629 lakes in China.We combined automatic extraction of training data and support vector machine classification to derive the spatial distribution of these large water bodies.The producer’s and user’s accuracies for MODIS images were91.06%and 89.81%,respectively,when compared with interpretation results from 30 m resolution Landsat images taken on similar days.Area changes,variability,inundation intensity,and rainy seasons of the 629 lakes were analyzed based on this multi-temporal lake database.The total area of the 629 lakes increased over the study period,primarily as a result of the expansion of lake areas on the Tibetan Plateau.There were 12 lakes with a maximum area[1,000 km2,and six of these decreased in area from 2000to 2010.The shrinkages of Poyang Lake and Dongting Lake were-54.76 and-25.08 km2/a,respectively.The area of lakes on Tibetan Plateau,in northern Xinjiang,northeastern Inner Mongolia,and northeastern China varied little,while lakes on the Yangtze Plain,in southern Inner Mongolia,and central Xinjiang fluctuated considerably.Inundation intensity increased for lakes on the Tibetan Plateau,in northern Xinjiang,Heilongjiang,and Jilin,while inundation extent decreased in central Xinjiang,southern Tibet,southern Inner Mongolia,Sichuan,and on the Yangtze Plain.This study is an attempt to develop high-frequency specific land cover maps to improve applicability of general land cover maps.The lake products serve as an important supplement to hydrologic data.The lake database enables the generation of new land surface process models,which could improve the precision of simulations,based on more accurate observations of dynamic lake systems.     

Influence of the amplitude ratio between two terahertz pulses on two-dimensional spectroscopy

The influence of the amplitude ratio between the two THz pulses on two-dimension THz spectroscopy （2DTS） has been studied theoretically via a classical method in which the expressions for the second-order nonlinearity were derived using perturbation approach, and the THz pulses were not treated as a delta function. Three types of nonlinear sources i.e., anharmonicity, nonlinear damping, and nonlinear coupling, are considered in a single mode system. The simulation results demonstrated that the amplitude ratio had a notable influence on the 2DTSs, and different sources have different influences. This study is promising for guiding future experiments.     

赫斯顿《他们眼望上苍》的黑人男性形象论析

佐拉·尼尔·赫斯顿的经典之作《他们眼望上苍》写的是女主人公珍妮对自己的独立意识所进行的一次自我发现到自我实现的历程。洛根·基利克斯是种族主义的受害者和男性霸权的代表,乔·斯塔克斯黑皮肤下拥有的是白灵魂,“甜点心”是一个新黑人男性形象,这三个黑人男性在珍妮找寻自我和实现自我的过程中扮演者不可或缺的角色。     

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。     

遗传算法在智能组卷系统中的应用研究

为更好地解决遗传算法在智能组卷过程中出现的早收敛问题,以及组卷质量和组卷速度呈负相关的问题,提出一种基于分段整数编码、多点交叉的遗传算法.通过大量实验,有针对性地对该算法中的编码结构、选择算子、交叉算子和变异算子进行优化设计;对相关控制参数进行合理调整,实验结果表明,该算法不仅有效地提高了组卷质量和组卷速度,而且具有很好的收敛性.