EDI膜块离子交换树脂层态分布研究及分析

为掌握电去离子(EDI)膜块内离子交换树脂层态分布规律,首先分析了EDI离子交换树脂迁移失效层、交换稳定层和水解保护层的工作原理和特点,随后通过实验测试了进水电导率和运行电流对离子交换树脂层态分布的影响。结果表明,水解保护层厚度与进水电导率负相关,与运行电流正相关,水解保护层是保证EDI膜块产水水质的关键点。在进水电导率≤10μS/cm(25℃)时,水解保护层厚度占整个树脂层厚度的比例≥11.43%,可以很好地保证EDI膜块产水电导率<0.1μS/cm(25℃)。在进水电导率为5μS/cm、产品水电导率<0.1μS/cm(25℃)时,提高运行电流可以增大水解保护层厚度,且水解保护层厚度与运行电流成线性关系。

Dynamic distribution and stem cell characteristics of Sox1-expressing cells in the cerebellar cortex

Bergmann glia cells are a discrete radial glia population surrounding Purkinje cells in the cerebellar cortex. Although Bergmann glia are essential for the development and correct arborization of Purkinje cells, little is known about the regulation of this cell population after the developmental phase. In an effort to characterize this population at the molecular level, we have analyzed marker expression and established that adult Bergmann glia express Soxl, Sox2 and Sox9, a feature otherwise associated with neural stem cells （NSCs）. In the present study, we have further analyzed the developmental pattern of Soxl-expressing cells in the developing cerebellum. We report that before becoming restricted to the Purkinje cell layer, Soxl-positive cells are present throughout the immature tissue, and that these cells show characteristics of Bergmann glia progenitors. Our study shows that these progenitors express Soxl, Sox2 and Sox9, a signature maintained throughout cerebellar maturation into adulthood. When isolated in culture, the Soxl-expressing cerebellar population exhibited neurosphere-forming ability, NSC-marker characteristics, and demonstrated multipotency at the clonal level. Our results show that the Bergmann glia population expresses Soxl during cerebellar development, and that these cells can be isolated and show stem cell characteristics in vitro, suggesting that they could hold a broader potential than previously thought.

Classification of tight sandstone reservoirs based on NMR logging

The traditional reservoir classification methods based on conventional well logging are inefficient for determining the properties,such as the porosity,shale volume,J function,and flow zone index,of the tight sandstone reservoirs because of their complex pore structure and large heterogeneity.Specifically,the method that is commonly used to characterize the reservoir pore structure is dependent on the nuclear magnetic resonance(NMR)transverse relaxation time(T2)distribution,which is closely related to the pore size distribution.Further,the pore structure parameters(displacement pressure,maximum pore-throat radius,and median pore-throat radius)can be determined and applied to reservoir classification based on the empirical linear or power function obtained from the NMR T2 distributions and the mercury intrusion capillary pressure ourves.However,the effective generalization of these empirical functions is difficult because they differ according to the region and are limited by the representative samples of different regions.A lognormal distribution is commonly used to describe the pore size and particle size distributions of the rock and quantitatively characterize the reservoir pore structure based on the volume,mean radius,and standard deviation of the small and large pores.In this study,we obtain six parameters(the volume,mean radius,and standard deviation of the small and large pores)that represent the characteristics of pore distribution and rock heterogeneity,calculate the total porosity via NMR logging,and classify the reservoirs via cluster analysis by adopting a bimodal lognormal distribution to fit the NMR T2 spectrum.Finally,based on the data obtained from the core tests and the NMR logs,the proposed method,which is readily applicable,can effectively classify the tight sandstone reservoirs.

Analysis of the dialectical relation between top coal caving and coal-gas outbtu rst

According to the different engineering mechanical states of top coal caving andnormal stoping of gaseous loose thick coal seams,the dialectical relation between thiscaving method and dynamic disasters was analyzed by simulating the change of stressstates in the process of top coal initial caving with different mining and caving ratios basedon the ANSYS10.0.The variation of elastic energy and methane expansion energy duringfirst top coal caving was analyzed by first weighting and periodic weighting and combiningwith coal stress and deformation distribution of top coal normal stoping as well as positiveand negative examples in top coal caving of outburst coal seam.The research shows thatthe outburst risk increases along with the increase of the caving ratio in the initial miningstage.In the period of normal stoping,when the mining and caving ratio is smaller than1:3 and hard and massive overlying strata do not exist (periodic weighting is not obvious),it is beneficial to control ground stress leading type outburst.Thus,it is unreasonable toprohibit top coal caving in dangerous and outburst prone areas.

Optimization of Composite Wind Turbine Blade Based on Modal Sensitivity

This study develops a method for the full-size structural design of blade,involving the optimal layer thickness configuration of the blade to maximize its bending stiffness using a genetic algorithm.Numerical differentiation is employed to solve the sensitivity of blade modal frequency to the layer thickness of each part of blade.The natural frequencies of first-order flapwise and edgewise modes are selected as the optimal objectives.Based on the modal sensitivity analysis of all design variables,the effect of discretized layer thickness on bending stiffness of the blade is explored,and 14 significant design variables are filtered to drive the structural optimization.The best solution predicts an increase in natural frequencies of first-order flapwise and edgewise blade modes by up to 12%and 10.4%,respectively.The results show that the structural optimization method based on modal sensitivity is more effective to improve the structural performance.

The Ecological Distributions of N, P Utilizing Bacteria and Heterotrophic Bacteria in the Moderate Hypoxia Zone of the Changjiang Estuary

The distributions of N utilizing bacteria (denitrifying bacteria and ammonifying bacteria) ,P utilizing bacteria (organic phosphobacteria and inorganic phosphobacteria) and heterotrophic bacteria in the Changjiang Estuary,and the roles of main environmental factors in distributing bacteria,are explored with observations from two cruises in June and August 2006.Comparisons between the two important periods of initial hypoxia phase (June) and developed hypoxia phase (August) show differences in both bacterial distributions and the associated main environmental factors.First,the primary group of ammonifying bacteria has larger magnitude with spatial maximum value in the hypoxic stations related to sediment in August.The phosphobacterial abundance and detection rates in August are much lower than those in June,but the denitrifying bacterial abundance becomes greater in August.However,the difference of heterotrophic bacterial abundance between June and August is not obvious.Second,main environmental factors influencing bacteria vary from initial hypoxia phase to developed hypoxia phase.Two parameters (salinity and NO3) in surface water and five environmental parameters (pH,salinity,PO43,NO3and temperature) in bottom water and surface sediment play major roles in the bacterial abundance in June,while different parameter combinations (salinity and PO43) in surface water and different parameter combinations (DO,DOC,NO3,PO43 and pH) in bottom water and surface sediment play major roles in August.Moreover,the bottom bacteria distributions in area south of 31 N are related to the position of the Taiwan Warm Current in June.The bacterial abundance and distribution may respond to the environmental change in the hypoxia processes of initial phase and developed phase.During the hypoxia processes,the whole structure of bacterial functional groups probably turns to different states,causing the recycling of nutrient regeneration and aggravating hypoxia regionally.