59 research outputs found
Accumulation of nitrate-N in the soil profile and its implications for the environment under dryland agriculture in northern China: A review
No full textFan, J., Hao, M. and Malhi, S. S. 2010. Accumulation of nitrate-N in the soil profile and its implications for the environment under dryland agriculture in northern China: A review. Can J. Soil Sci. 90: 429-440. Nitrate (NO(3)(-)) leaching and water contamination have become a worldwide concern. In this review, some examples are presented to show the extent and magnitude of NO(3)(-)accumulation in the soil profiles and its potential effects on contamination of ground water and surface water under dryland farming in northern China. Climatic and management factors affecting NO(3)(-) leaching are also discussed. In northern China, rainfall is relatively sparse, but the high intensity of precipitation and porous soils play an important role in the accumulation of NO(3)-N in soil and its subsequent leaching in the soil profile. There is a risk of nitrate accumulation and leaching when high rates of fertilizer N are applied to improve crop yields, and it becomes even worse when conventional land use is changed from cereal crops to vegetable crops and fruit orchards. Under such conditions, shallow ground water might be polluted by NO(3)(-). This suggests that more attention should be paid to prevent this problem by using best management practices, especially by controlling the amount of N fertilizer input, balanced fertilization, split N application, inclusion of crops with deep taproots in the rotation and minimizing summer fallow (especially tilled) frequency
Continuous-flow, electrically-triggered, single cell-level electroporation
No full textElectroporation creates transient openings in the cell membrane, allowing for intracellular delivery of diagnostic and therapeutic substances. The degree of cell membrane permeability during electroporation plays a key role in regulating the size of the delivery payload as well as the overall cell viability. A microfl uidic platform offers the ability to electroporate single cells with impedance detection of membrane permeabilization in a high-throughput, continuous-fl ow manner. We have developed a fl ow-based electroporation microdevice that automatically detects, electroporates, and monitors individual cells for changes in permeability and delivery. We are able to achieve the advantages of electrical monitoring of cell permeabilization, heretofore only achieved with trapped or static cells, while processing the cells in a continuous-fl ow environment. We demonstrate the analysis of membrane permeabilization on individual cells before and after electroporation in a continuous-fl ow environment, which dramatically increases throughput. We have confi rmed cell membrane permeabilization by electrically measuring the changes in cell impedance from electroporation and by optically measuring the intracellular delivery of a fl uorescent probe after systematically varying the electric fi eld strength and duration and correlating the pulse parameters to cell viability. We fi nd a dramatic change in cell impedance and propidium iodide (PI) uptake at a pulse strength threshold of 0.87 kV/cm applied for a duration of 1 ms or longer. The overall cell viability was found to vary in a dose dependent manner with lower viability observed with increasing electric fi eld strength and pulse duration. Cell viability was greater than 83% for all cases except for the most aggressive pulse condition (1 kV/cm for 5 ms), where the viability dropped to 67.1%. These studies can assist in determining critical permeabilization and molecular delivery parameters while preserving viability.Peer reviewe
Synthesis, characterization and size control of zerovalent iron nanoparticles anchored on montmorillonite
No full textFlood prevention on the lower reaches of the Rellow River
No full textProceedings of a congerence in Zhenzhou, China, 1990: Gong Shiyan, Wu Zhiyao: Introduction. Bao Zicheng, Zhang Mingde, Wang Rudiu: Strenghtening of dykes by Warping. Cheng Zidao, Liu Yuli: To remedy hidden defects in dykes by probing with pointed steed rods and subsequent grouting. Hu Yisan: River training works on the lower reaches of the Yellow River. Shen Hongxin, Xu Fuling: Engineering structures for river correction on the lower reaches of the Yellow River. Bao Xicheng, Zho Guangming, Wang Hongxiang: Ice dam on the lower reaches of the Yellow River. Liu7 Ruyun, Tong Linlang: Organizing for flood protection on the lower reaches fo the Yellow river. A brief account of Dongpinghu detention reservoir
Development of a continuous-flow, automated microfluidic device for single cell level electroporation
No full textElectroporation is a powerful transfection technique that creates transient openings in the cell membrane by applying an electric field, allowing for the intracellular delivery of diagnostic and therapeutic substances. The ability to detect and control the degree of cell membrane permeability plays a key role in determining the size of the delivery payload, while safeguarding the overall cell viability. In order to create a universal electroporation system, this dissertation describes the development of a continuous flow electroporation microdevice that automatically detects, electroporates, and monitors individual cells for changes in permeability and delivery. In contrast to devices that immobilize individual cells for impedance analysis, this work demonstrates the capability to manipulate single cells under flow and real-time analysis of membrane permeabilization before and after electroporation, which dramatically increasing the number of cells which can be electroporated and analyzed. Using an electric circuit model, and Multiphysics computational tools, the key parameters for successful cell membrane permeabilization detection in a flow environment were determined. By varying the electric field parameters, we demonstrate the direct control of cell membrane permeabilization by electrically measuring the electroporation-induced cell membrane impedance change and by optically measuring the delivery of a fluorescent probe. Viability of the electroporated cells following collection also demonstrates a correlation with the applied pulse strength. By extending the device capability to include dynamic pulse adjustment according to the real-time feedback information on cell viability, an intelligent electroporation system capable of potentially maximizing delivery efficiency and cell viability can be thus realized.Ph.D.Includes bibliographical referencesby Mingde Zhen
Mingde tang (明德堂)
No full textFront view of a temple in an extremely desolate building, probably a private temple; it was not possible to enter [1]. Front view [2]. An indication that the temple is not much frequented, an overgrown bicycle [3]. Altar view with a Buddha statue [4]. Left side of the altar [5].Non UBCUnreviewedAuthor Affiliations: University of Gent, University of Utah, Capital Normal University 首都师范大学FacultyGraduat
Montmorillonite-supported magnetite nanoparticles for the removal of hexavalent chromium [Cr(VI)] from aqueous solutions
No full textRemoval of hexavalent chromium [Cr(VI)] from aqueous solutions by the diatomite-supported/unsupported magnetite nanoparticles
No full textFacile preparation of hierarchically porous carbon using diatomite as both template and catalyst and methylene blue adsorption of carbon products
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