Product analysis of partial discharge damage to oil-impregnated insulation paper

Surface products of oil-impregnated insulation paper during the damage process caused by partial discharge (PD), as well as gas within the cavity, were studied. An optical microscope and a scanning electron microscope (SEM) were used to investigate surface morphology, while an infrared spectroscopy (IR) and an X-ray photoelectron spectroscopy (XPS) were used to study surface products and their components. The volume variation in cavity gas was also analyzed. Furthermore, gas constituents and their relevant contents were studied using a gas chromatography-mass spectrometer (GC-MS). The study results reveal the following: during the PD damage process, the total gas volume and the content of electronegative gasses alternately decline and increase, while discharge types alternate between pulse type and pseudo-glow type (or glow type); “surface droplets” and “crystalline solids” appear on the insulation surface one after another; surface droplets mainly consist of (CO)-group-containing compounds, whereas crystalline solids are mainly carboxylic acids, with carboxyl groups also found in cellulose chains; and the discharge type related to the oxidization of decomposition products is the main factor that determines the state (liquid or solid) of the surface products.     

Graphene oxide thin film coated quartz crystal microbalance for humidity detection

In this paper, we demonstrated that chemically derived graphene oxide (GO) thin film as a humidity sensitive coating deposited on quartz crystal microbalances (QCMs) for humidity detection. By exposing GO thin film coated QCMs to various relative humidity (RH) environments at room temperature, the humidity sensing characteristics of the QCMs such as sensitivity and linearity, response and recovery, humidity hysteresis were investigated. The experiment results show that GO thin film coated QCMs exhibit an excellent humidity sensing performance. Moreover, the possible humidity sensing mechanism of GO thin film coated QCMs was also investigated by monitoring the crystal's motional resistance change. It is suggested that the frequency response of the QCMs is dependent on water molecules adsorbed/desorbed masses on GO thin film in the low RH range, and on both water molecules adsorbed/desorbed masses on GO thin film and variations in interlayer expansion stress of GO thin film derived from swelling effect in the high RH range.     

Neural specificity of acupuncture stimulation from support vector machine classification analysis

Acupoint specificity, as a crucial issue in acupuncture neuroimaging studies, is still a controversial topic. Previous studies have generally adopted a block-based general linear model (GLM) approach, which predicts the temporal changes in the blood oxygenation level-dependent signal conforming to the “on-off” specifications. However, this method might become impractical since the precise timing and duration of acupuncture actions cannot be specified a priori. In the current study, we applied a data-driven multivariate classification approach, namely, support vector machine (SVM), to explore the neural specificity of acupuncture at gall bladder 40 (GB40) using kidney 3 (KI3) as a control condition (belonging to different meridians but the same nerve segment). In addition, to verify whether the typical GLM approach is sensitive enough in exploring the neural response patterns evoked by acupuncture, we also employed the GLM method to the same data sets. The SVM analysis detected distinct neural response patterns between GB40 and KI3 — positive predominantly for the GB40, while negative following the KI3. By contrast, group analysis from the GLM showed that acupuncture at these different acupoints can both evoke similar widespread signal decreases in multiple brain regions, and most of these regions were spatially overlapped, mainly distributing in the limbic and subcortical structures. Our findings may provide additional evidence to support the specificity of acupuncture, relevant to its clinical efficacy. Moreover, we also proved that GLM analysis is prone to be susceptible to errors and is not appropriate for detecting neural response patterns evoked by acupuncture stimulation.     

Enhanced superconducting properties in epitaxial FeSe thin films with self-assembled Fe3O4 nanoparticles

In this paper we report epitaxial tetragonal iron selenide thin films grown on single crystal SrTiO₃ (STO) (0 0 1) and MgO (0 0 1) substrates by a pulsed laser deposition (PLD) technique. Deposition temperature and annealing process are found to be critical for achieving the tetragonal phase and the optimum superconducting properties of the films. The critical transition temperature of the thin films ranges from 2 K to 11.5 K depending on the deposition temperature and annealing condition. The samples with higher critical transition temperatures show better film crystallinity along with self-assembled Fe₃O₄ nanoparticles (～15 nm in average particle size) in the films according to both X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. Besides the better crystallinity achieved in the films, the formation of Fe₃O₄ nanoparticles could assist the formation of the tetragonal FeSe phase and thus lead to the enhanced superconducting properties.     

离子交换法从发酵液中提取聚苹果酸

用离子交换法提取发酵液中的聚苹果酸,比较了不同型号的阴离子树脂对聚苹果酸的静态吸附量,其中以D296树脂对聚苹果酸的吸附量最大.通过静态和动态方法,考察了不同操作条件对固定床分离工艺的影响.结果表明,发酵液经预处理后,调pH至9.5,以lBV/h流速上柱吸附,上柱量为4BV;用0.5mol/L NaCl洗脱,速度为1BV/h.该工艺能够将发酵液中大部分杂质去除,PMLA样品的纯度达到 93.2%,提取收率为79.46%.     

Preferential adsorption of extracellular polymeric substances from bacteria on clay minerals and iron oxide

The adsorption of extracellular polymeric substances (EPS) from Bacillus subtilis on montmorillonite, kaolinite and goethite was investigated as a function of pH and ionic strength using batch studies coupled with Fourier transform infrared (FTIR) spectroscopy. The adsorption isotherms of EPS on minerals conformed to the Langmuir equation. The amount of EPS-C and -N adsorbed followed the sequence of montmorillonite>goethite>kaolinite. However, EPS-P adsorption was in the order of goethite>montmorillonite>kaolinite. A marked decrease in the mass fraction of EPS adsorption on minerals was observed with the increase of final pH from 3.1 to 8.3. Calcium ion was more efficient than sodium ion in promoting EPS adsorption on minerals. At various pH values and ionic strength, the mass fraction of EPS-N was higher than those of EPS-C and -P on montmorillonite and kaolinite, while the mass fraction of EPS-P was the highest on goethite. These results suggest that proteinaceous constituents were adsorbed preferentially on montmorillonite and kaolinite, and phosphorylated macromolecules were absorbed preferentially on goethite. Adsorption of EPS on clay minerals resulted in obvious shifts of infrared absorption bands of adsorbed water molecules, showing the importance of hydrogen bonding in EPS adsorption. The highest K values in equilibrium adsorption and FTIR are consistent with ligand exchange of EPS phosphate groups for goethite surface. The information obtained is of fundamental significance for understanding interfacial reactions between microorganisms and minerals.     

重离子束治疗肿瘤临床研究

文章综述了重离子束在物理学、生物学、临床治疗等方面的优势,以及在放射生物学方面的基础实验研究内容。分析总结了国内外重离子束辐照治疗肿瘤的临床研究结果。其中,日本已接受治疗了约6 000 名不同类型的肿瘤患者,并取得较高的局部控制率和生存率;德国在头颈部肿瘤临床治疗方面取得了巨大的成功;在兰州重离子研究装置(HIRFL) 肿瘤治疗终端上,中国科学院近代物理研究所联合甘肃省肿瘤医院及兰州军区总医院对肿瘤患者的重离子治疗已进入临床试验阶段。甘肃省肿瘤医院治疗结果显示:43 例患者通过影像学检查评价疗效,客观有效率(CR+PR)为71.4%,主要急性放射损伤为1-2 级皮肤反应(红斑形成和脱皮),发生率为61.9%,治疗1 个月后随访结果显示重离子束(12C6+)对深部肿瘤具有较好的局部控制作用,且无严重不良反应发生。This article reviews the advantages of heavy ion in physical, biological and clinical aspects, discusses the radio-biological basis of experiment research, and summarizes clinical results of heavy ion beam treatment on tumor at home and abroad. Japan has accepted and treated about 6000 cancer patients of different types with high local control rates and survival ones. Germany has achieved great success in head and neck tumor clinical treatment. Institute of Modern Physics, Chinese Academy of Sciences (IMP-CAS), Tumor Hospital of Gansu Province and Lanzhou General Hospital of PLA have begun clinical trial on heavy ion treatment of deep-seated tumors after the shallow-seated tumor therapy has been done at HIRFL (Heavy Ion Research Facility in Lanzhou). The treatment results of Tumor Hospital of Gansu Province show that the objective response rate (CR+PR) is 71.4% and the rate of 1-2 levels radiation injury to skin reactions (erythema and desquamation) is 61.9% when we evaluate the 43 patients by means of maging. The results of case follow-up after treatment in 1 month indicate that the deep-seated tumor therapy with heavy ion beam has high local control rates without severe adverse effect.     

毫米波/亚毫米波准光馈电系统设计

准光馈电系统是毫米波/亚毫米波传感器的关键组成部分。阐述了毫米波/亚毫米波准光系统的基本设计理论与方法;归纳分析了常用准光无源器件的种类、作用及设计流程等相关问题。并以此为基础,构造出三类能够实现双极化接收功能、双模复合工作的准光馈电系统,并详细描述其工作原理。最终,通过仿真优化设计出与馈电系统相对应的毫米波频段双反射面天线,并采用固定副面、主面机械扫描的形式实现了传感器波束10的空域覆盖。收稿日期:; 修订日期:     

改进的QPSO算法在电网故障诊断系统中的应用

电网故障诊断系统通常基于建立的解析模型,通过分析保护和断路器的动作信息来推断可能的故障位置,从而识别保护与断路器的故障元件和误动作。本文根据保护动作原理,构建了一种改进的解析模型,并采用改进的量子粒子群算法对其目标函数进行优化求解。该模型不仅充分考虑到了保护和断路器的误动与拒动、断路器失灵保护等问题,且能辨识告警信息的误报和漏报。实验结果表明改进的算法不仅使故障诊断结果更精确,并能使故障情况很清晰的表示出来,有利于故障的及时恢复,同时使模型的运算速度和稳定性也进一步得到了提高。