MH/Ni电池储存性能研究

研究了氢镍电池长期储存性能,发现国内氢镍电池储存后普遍性能下降较大,主要原因是由正极性能下降所致。     

N-乙酰半胱氨酸治疗慢性阻塞性肺疾病患者疗效和作用机制研究

目的: 探讨N-乙酰半胱氨酸(NAC)治疗慢性阻塞性肺疾病(COPD)的临床疗效和作用机制。方法: 将78 例COPD 患者随机分为治疗组和对照组,观察其治疗前后对痰液炎症细胞计数及核因子-kB(NF-kB)、白细胞介素8(IL-8)、肿瘤坏死因子α(TNF-α)水平的影响,以及对临床症状、肺功能指标和血丙二醛(MDA)、全血超氧化物歧化酶(SOD)和血清血管紧张素Ⅰ转换酶(ACE)活性及血内皮素-1(ET-1)含量的变化情况,并与20 名健康人作比较。结果: 78 例COPD 患者中脱落5 例(治疗组3 例,对照组2例)。NAC 治疗COPD 的总显效率为72.50 %,总有效率为87.50 %,与对照组比较有显著性差异(P<0.05)。与对照组比较,治疗组能明显改善肺功能指标(FEV1 、FVC 、mPAP)和血MDA 、SOD 、ACE 活性及ET-1 含量(P<0.05)。治疗后治疗组痰液中性粒细胞(PMN)、非中性粒细胞(mPMN);IL-8 、TNF-α和NFkB活性(A 值)较治疗前显著降低(P<0.01),降低作用优于对照组(P<0.05),治疗期间未见明显毒副作用。结论: NAC 治疗COPD 患者可改善其临床症状和肺功能,安全性良好,通过增强抗氧化能力和减轻COPD 患者气道炎症反应而发挥其治疗作用。     

漂烫和冻结对马铃薯细胞结构和质地特性影响的实验研究

质地特性是评估冻制果蔬质量优劣的重要指标。研究了漂烫和冻结对马铃薯惩质地特性的影响,发现低温短时间漂烫对马铃薯质地影响较小,速冻或慢冻都会大幅度地降低马铃薯的质地特性,速冻比慢冻好,马铃薯的质地特性与加工过程中细胞受损情况有一定关系。     

Chitosan scaffolds formation by a supercritical freeze extraction process

A crucial step of Tissue Engineering (TE) approach is the fabrication of 3-D biodegradable scaffolds. It has been achieved using various techniques, such as gas foaming, fiber bonding, solvent casting/particulate leaching, phase separation and 3D-printing. Each technique presents specific advantages and disadvantages; but, all of them share the difficulty to obtain simultaneously the macro, micro and nanostructure. In this work, a Supercritical Freeze Extraction Process (SFEP) is proposed for the formation of chitosan structures suitable for TE applications. We showed that it is possible to produce chitosan scaffolds characterized by a micrometric cellular structure, nanofibrous sub-structure and porous surfaces. The low process temperature allows to obtain 3-D solids, whose structure is preserved during supercritical drying. Preliminary results on cell cultivation confirmed that the generated chitosan scaffolds are characterized by a morphology that is potentially suitable for TE applications. A good cell adhesion was obtained and a large percentage of living cells was observed. This result can depend on the micrometric morphology of the scaffolds, that assures a good nutrient diffusion, and on the nanometric sub-structure that allows an adequate cells adhesion.     

Development of error-compensating UI for autonomous production cells

This contribution deals with the impact of human error on the overall system reliability in flexible manufacturing systems (FMS). Autonomous production cells are used to illustrate an error-compensating system design on the basis of Sheridan's (1997) paradigm of supervisory control. In order to specify human errors and their effects in terms of system disturbances, a taxonomy of system disturbances is recommended. This taxonomic approach was derived by a value benefit analysis and is based on HEDOMS (Human Error and Disturbance Occurrence in Manufacturing Systems) with slight modifications and Reason's GEMS (Generic Error Modelling System). The taxonomy is used for data acquisition. Next, a risk priority equivalent to FMEA (Failure Mode and Effect Analysis) is introduced to structure the data according to their relevance. Then, Vicente's and Rasmussen's guidelines (1987) for an ecological interface design are related to the paradigm of supervisory control. On the basis of these guidelines four case studies are presented to show their successful applicability for interface design in FMS.     

Experimental study on water transport in membrane humidifiers for polymer electrolyte membrane fuel cells

This paper presents an experimental setup for the measurement of water transfer in membrane humidifiers for automotive polymer electrolyte membrane (PEM) fuel cells at different process conditions. This setup was used to determine steady-state water permeation through perfluorinated sulfonic acid (PFSA)-based polymer membranes. The process conditions were varied within a relative humidity in the feed stream of RH = 30–90 %, absolute pressures of p = 1.25–2.5 bar, and temperatures of T = 320–360 K. The examined membranes are Nafion® membranes of different thicknesses (Nafion® 211, 212 and 115) and an experimental composite membrane manufactured by W. L. Gore & Associates. It was found that the overall water permeance is affected by both the mass transfer resistance of the membrane and the resistances in the boundary layers of the adjacent gas streams. The overall permeance is a strong function of water activity, with high levels of relative humidity showing the highest overall permeance. The absolute pressure only affects the overall permeance by affecting the diffusion in the boundary layers. Lower pressures are preferable for high overall water permeances. Increasing temperatures favor diffusion in the membrane and the boundary layers but lead to lower sorption into the membrane. The thicker Nafion® membranes show lower overall permeance at higher temperatures, while the overall permeance of the composite membrane shows no dependency on the temperature. Investigation of membrane humidifiers in counter-, co-, and cross-flow shows that the flow configuration in our setup has very little impact on the water flux in the humidifier.     

Interface states characterization in heterojunction solar cells from CV-GV measurements and modeling

A new method is proposed to extract interface states density D_it at the hydrogenated amorphous/crystalline silicon interfaces (aSi:H/cSi) of heterojunction solar cells - HET. This technique based on CV and GV measurements consists in adapting standard electrical D_it models for MOS structures to the specific case of HET solar cells. In particular, a parasitic conductance is introduced to account for the high leakage current of the diode in the forward regime. The relevance and accuracy of such an analytical model is then demonstrated by comparison with experimental results and with more complex numerical approaches. Finally, this technique enables us to demonstrate the high quality of the interface of HET solar cells which exhibit D_it levels below 10¹¹ defects per cm².     

Title: Using Alignment and 2D Network Simulations to Study Charge Transport Through Doped ZnO Nanowire Thin Film Electrodes

Factors affecting charge transport through ZnO nanowire mat films were studied by aligning ZnO nanowires on substrates and coupling experimental measurements with 2D nanowire network simulations. Gallium doped ZnO nanowires were aligned on thermally oxidized silicon wafer by shearing a nanowire dispersion in ethanol. Sheet resistances of nanowire thin films that had current flowing parallel to nanowire alignment direction were compared to thin films that had current flowing perpendicular to nanowire alignment direction. Perpendicular devices showed ～5 fold greater sheet resistance than parallel devices supporting the hypothesis that aligning nanowires would increase conductivity of ZnO nanowire electrodes. 2‐D nanowire network simulations of thin films showed that the device sheet resistance was dominated by inter‐wire contact resistance. For a given resistivity of ZnO nanowires, the thin film electrodes would have the lowest possible sheet resistance if the inter‐wire contact resistance was one order of magnitude lower than the single nanowire resistance. Simulations suggest that the conductivity of such thin film devices could be further enhanced by using longer nanowires.