The effect of oxygen tension on colony formation and cell proliferation of amniotic fluid cellsin vitro

The effects of reduced oxygen concentrations in the gas phase over the culture medium on colony formation and cell proliferation were investigated in high and low cell density primary and secondary cultures of amniotic fluid cells. Using two standard culture methods (25 cm² plastic flasks and Leighton type tubes) a significantly reduced culture time was observed at high cell density for mass cultures by incubation within a low oxygen tension gas phase (2.5 per cent to 7.5 per cent O₂) instead of conventional air (18 per cent O₂). At low cell density colony formation was significantly enhanced in cultures grown at reduced oxygen tension. Using gas permeable membranes as support, lowering the oxygen tension from 7.5 per cent to 2.5 per cent yielded an increase in plating efficiency of cells from approximately 5 per cent to 25 per cent, whereas plating efficiency was less than 2 per cent for cells grown at ambient 18 per cent O₂. It is suggested that low oxygen tension in the gas phase is an effective means of enhancing clonal growth in amniotic fluid cell cultures, thereby reducing both culture time and risk of culture failure.     

固定化酵母菌对活性艳蓝KN-R的脱色研究

采用海藻酸钙加活性碳的方法对酵母菌进行固定化。正交试验结果表明，三者合适配比为海藻酸钠3％，活性碳10％，氯化钙4％。此方法制得的凝胶颗粒机械强度好、经久耐用。固定化酵母菌凝胶小球最适条件为：培养时间为48h，培养温度为37℃，培养基pH为3．0，凝胶量为10g。固定化细胞经多次脱色后能重复使用，4次脱色后其脱色率还达79．2％。     

A Parallel Study of SAR Levels in Head Tissues for Three Antennas Used in Cellular Telephones: Monopole, Helix and Patch

Summary This paper is a comparative study of several antennas commonly used in cellular telephones. These include a monopole, a helix-monopole and a patch antenna. Each one of these structures is modeled and numerically tested using finite-difference time-domain simulation and human models based on magnetic-resonance images, which allow for inclusion of details of the human body in the simulation. The testing procedure involves antenna simulation in the proximity of the human head. The behavior of each antenna is evaluated for variable distances from the head geometry (0, 1, 2, 4, 8 and 16 mm). Continuous waveform, representative of the sources used in mobile telephones, (250 mW, 1.8 GHz) is used as the form of the antenna excitation. The simulation outputs used as measures for this comparative study include transmitting and receiving antenna characteristics and the specific absorption rate (SAR). The SAR levels for the head tissues are calculated for and with accordance to the two currently accepted standards: Federal Communications Commission (FCC) and International Commission on Non-Ionizing Radiation Protection (ICNIRP). The computed SAR levels within each of the considered tissues vary for the three antennas under investigation and are within the determined health safety standards. Results suggest that the patch antenna may be the structure of choice when considering safety standards, as its radiation yields the lowest local SAR in the head tissues.     

The impact of pesticides on oxidative stress level in human organism and their activity as an endocrine disruptor

Pesticides cause serious environmental and health problems both to humans and animals. The aim of this review is to discuss selected herbicides and fungicides regarding their mode of action and their influence on basic oxidative stress parameters and endocrine disruption properties tested in selected cell cultures in vitro. Because of numerous difficulties which animal studies are subject to, cell cultures are an excellent experimental model reflecting human exposure to different pesticides through all relevant routes. This experimental model can be used to monitor aggregate and cumulative pesticide exposures.     

三氯卡班可以影响肾小管上皮细胞的屏障功能

三氯卡班(TCC)是一种被广泛应用于个人护理用品中的广谱型亲脂性杀菌剂,已在多种环境介质和生物体中检出。因其潜在的环境蓄积、生物累积和生物毒性效应,日益受到学者们的关注。借助TCC对NRK-52E(大鼠肾小管上皮细胞)的毒性暴露实验,通过检测细胞活力、以及与跨膜电阻和紧密连接相关的连接黏附分子1(JAM~(-1),junctional adhesion molecule 1)的蛋白表达水平,研究了TCC潜在的肾脏毒性效应。结果显示,10μmol·L~(-1)TCC处理48 h时培养细胞呈现不规则的集落;10μmol·L~(-1)和20μmol·L~(-1)TCC处理NRK-52E 24 h、48 h和72 h后可以显著抑制细胞生长;3.57μmol·L~(-1)TCC(生长抑制的48 hIC20)处理NRK-52E 48 h可以显著抑制细胞间紧密连接蛋白JAM~(-1)的表达量,并降低跨膜电阻,影响肾脏的屏障功能。本研究的结果能够为进一步揭示TCC对动物的毒害机制、评估其对动物的健康风险提供数据支持。     

微生物-光-电化学耦合技术降解污染物和回收能源的研究进展

微生物电化学技术能同时实现污染物去除和能量回收，但存在污染物去除种类有限及产能效率低的局限，近几年将可再生的太阳能引入微生物电化学技术的微生物-光-电化学耦合技术应运而生。本文简要介绍了微生物-光-电化学耦合技术的发展背景和研究现状，对该技术现有的耦合形式进行分类，并对各种形式的耦合机理进行详细的阐释，最后对其未来的发展进行了展望。     

Identifying and modeling key trade-offs between hydrogen fuel cell and electric vehicles

Through a sensitivity analysis, the trade-off between vehicle range and CO₂ emissions is investigated as a function of electric emissions coefficient. Various powertrains were analysed for use in a small crossover sport utility vehicle. Gasoline, gasoline electric hybrid, diesel, fuel cell and battery electric vehicles (BEVs) were considered. Using various upstream fuel pathways and a model for vehicle performance, emissions and energy use were estimated. The hydrogen fuel cell vehicle was found preferable to BEVs under conditions of high CO₂ emissions per kW-hr and a high vehicle range requirement. The BEV was preferable for all other conditions.     

Investigation of titanium liquid/gas diffusion layers in proton exchange membrane electrolyzer cells

In a proton exchange membrane electrolyzer cell (PEMEC), liquid/gas diffusion layer (LGDL) is expected to transport electrons, heat, and reactants/products to and from the catalyst layer with minimum voltage, current, thermal, interfacial, and fluidic losses. In addition, carbon materials, which are typically used in PEM fuel cells (PEMFCs), are unsuitable in PEMECs due to the high ohmic potential and highly oxidative environment of the oxygen electrode. In this study, a set of titanium gas diffusion layers with different thicknesses and porosities are designed and examined coupled with the development of a robust titanium bipolar plate. It has been found that the performance of electrolyzer improves along with a decrease in thickness or porosity of the anode LGDL of titanium woven meshes. The ohmic resistance of anode LGDL and contact resistance between anode LGDL and the anode catalyst play dominant roles in electrolyzer performance, and better performance can be obtained by reducing ohmic resistance. Thin titanium LGDLs with straight-through pores and optimal pore morphologies are recommended for the future developments of low-cost LGDLs with minimum ohmic/transport losses.     

Performance evaluation of reverse logistics enterprise – an agent-based simulation approach

Reverse logistics (RL) has been applied in many industries and sectors since its conception. Unlike forward logistics, retracing consumer goods from the point of consumption to the point of inception is not a well-studied process. It involves many uncertainties such as time, quality and quantity of returns. The returned products can be remanufactured, have parts harvested, or be disposed safely. It is important to implement these activities in a cost-effective manner. The aim of this research is to measure the performance of the RL enterprise with the help of an agent-based simulation model. The major entities in the RL network are considered as Agents that can act independently. There are several different agents: collector agent, sorting-cum-reuse agent, remanufacturing agent, recycler agent, supplier agent and distributor agent. The individual performances of the agents are measured and recommendations are given to improve their performance, leading to the enhancement of the total performance of the RL enterprise. The approach is applied to a case study involving cell phone remanufacturing.     

3种镉超富集植物毛状根体系对镉胁迫响应的比较

近年来,转基因毛状根组织被越来越多地应用于重金属和有机污染物的植物修复技术研究中,已成为进行污染物毒性响应机制研究的便捷的实验室工具。为了探究龙葵、油菜、芥菜3种镉(cadmium,Cd)超富集植物对Cd毒性胁迫响应的差异,以诱导出的3种植物毛状根为研究材料,从毛状根的生长状态、富集Cd的能力、根组织细胞的凋亡程度和抗氧化酶活性等方面进行了探讨。结果表明:Cd浓度为0~50μmol·L-1时,龙葵、油菜、芥菜毛状根受Cd毒害的影响都不明显;Cd浓度为75~100μmol·L-1时,龙葵、油菜、芥菜毛状根均表现出对Cd胁迫的防御响应。在较高的Cd浓度(100μmol·L-1)下,龙葵毛状根的生物量受Cd毒害的影响最小,芥菜次之,油菜受影响最大;同时龙葵毛状根富集的Cd含量最高(745.0μg·g-1),芥菜次之(681.4μg·g-1),油菜最差(505.2μg·g-1)。龙葵、油菜、芥菜毛状根在Cd胁迫下的细胞凋亡水平均随Cd浓度的升高而升高,当Cd浓度为100μmol·L-1时,龙葵毛状根比油菜和芥菜毛状根的细胞凋亡程度均低。同时3种植物毛状根在不同浓度Cd处理下抗氧化酶活性的变化有一定差异。从上述结果综合来看,龙葵毛状根受Cd毒害的影响最小、富集Cd的能力最好,是进一步开展Cd超富集植物转基因改造研究的较好的实验室载体。