Rate of nitrogen desorption from liquid iron-carbon and iron-chromium alloys with argon

The rate of nitrogen desorption from inductively stirred liquid iron, iron-carbon, and iron-chromium alloys with argon carrier gas has been measured by the sampling method for a wide range of nitrogen, carbon, and chromium contents mainly at 1600 °C. The results obtained by the present work and other data of previous investigators are used to clarify the reaction mechanism of nitrogen desorption from liquid iron. The rate of nitrogen desorption from liquid iron and iron alloys is second order with respect to nitrogen content in the metal under the present condition, and mutual relationships among interfacial chemical reaction, liquid-phase mass transfer, and gas-phase mass transfer are elucidated. The effects of oxygen and sulfur on the rate of nitrogen desorption are given byk _' ^{c ’} = 3.15?_N ² [1/(1 + 300a₀ + 130a_s)]. Carbon dissolved in iron increases the rate of nitrogen desorption, and chromium decreases it. The effects of these alloying elements can be explained by the change of the nitrogen activity in the metal.     

Toughened glass-ceramics in the ZrO2-Al2O3-SiO2 system prepared by the sol-gel process

Monolithic glass-ceramics containing Al₂O₃ or TiO₂ were prepared in the ZrO₂-SiO₂ system by the sol-gel process from metal alkoxides. Tetragonal ZrO₂ was precipitated by heat treatment at 900–1200 °C and its crystal growth was increased by adding TiO₂ or Al₂O₃. Further heating at higher temperature resulted in the precipitation of zircon and monoclinic ZrO₂ which was transformed from tetragonal ZrO₂. The addition of Al₂O₃ had less effect on both the tetragonal-to-monoclinic ZrO₂ transformation and the precipitation of zircon. The fracture toughness increased as the size of tetragonal ZrO₂ particles increased and then decreased with the appearance of monoclinic ZrO₂ or zircon. The fracture toughness of the glass-ceramics was measured in the glass-forming regions of the ZrO₂-Al₂O₃-SiO₂ system. The fracture toughness was sensitively dependent on both Al₂O₃ and ZrO₂ content, of which the highest value achieved was 9 MPa m^1/2 for the 50ZrO₂·10Al₂O₃·40SiO₂ composition.     

Simultaneous measurement of surface tension and kinematic viscosity using thermal fluctuations

We have developed a surface laser-light scattering apparatus to measure simultaneously surface tension and kinematic viscosity. In this method, we can obtain the surface properties by the laser heterodyne detection of light scattered from thermally excited capillary waves (called ripplon), which are typically of low amplitude (1 nm) and a characteristic wavelength (100m). Two gratings (d=100 and 200m) were employed to select the wave number of the capillary waves and to produce a reference beam for heterodyne detection. It was found through an experimental study on water that this contact-free method has considerable potential for application to measurements under extreme conditions such as high temperatures and high pressures.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Thermal Conductivity of Binary Refrigerant Mixtures of HFC-32/125 and HFC-32/134a in the Liquid Phase

The liquid thermal conductivity of mixtures of HFC-32/125 and HFC-32/134a was measured using the transient hot-wire apparatus in the temperature ranges from 213 to 293 K and from 193 to 313 K, respectively, in the pressure range from 2 to 30 MPa and with HFC-32 mass fractions of 0.249, 0.500, and 0.750 for each system. The uncertainty of the thermal conductivity was estimated to be ±0.7%. For practical applications, the thermal conductivity data for the two mixtures were represented by a polynomial in temperature, pressure, and mass fraction of HFC-32 with a standard deviation of 1.0%.     

Application of B MAS-NMR to the characterization of boron in coal fly ash generated from Nantun coal

Boron and its compounds are environmentally hazardous substance and are well-known condensed products that appear in coal fly ash during combustion of coal in coal-fired electric power stations. In a previous study, we suggested that boron in coal fly ash obtained from Nantun coal in China, identified as Ash-N, may exist on the surface of relatively large coal fly ash particles or as very fine particles generated by homogeneous nucleation. Although the characterization of boron in coal fly ash is important for its effective stabilization or removal, its detection is quite difficult because of its low concentration in coal fly ash and its light atomic weight. In the present work, solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) technique has been applied to reveal the local chemical structures of boron in Ash-N. In the ¹¹B MAS-NMR spectrum of Ash-N, two peaks which are attributed to a three-oxygen coordinated boron unit (BO₃) and a four-oxygen coordinated boron unit (BO₄) were observed with high resolution. We have estimated quadrupole parameters of the BO₃ unit in Ash-N using computer simulation, and we have fingerprinted these moieties with the parameters of borates. The result of the present analysis shows that calcium- or magnesium-bearing orthoborate or pyroborate are the most likely forms of boron in Ash-N.     

Effect of nitrous oxide on spinal dorsal horn WDR neuronal activity in cats

The effects of nitrous oxide (75%) on the spinal dorsal born wide dynamic range (WDR) neuronal activity were studied in either spinal cord intact or spinal cord-transected cats. Extracellular activity was recorded in the dorsal horn from single WDR neurons responding to noxious and non-noxious stimuli applied to the cutaneous receptive fields on the left bind foot pads of intact or decerebrate, spinal cord-transected (L 1-2) cats. The experiment was divided into four sections as follows: (1) When 10 micrograms of bradykinin (BK) was injected into the femoral artery ipsilateral to the recording site as the noxious test stimulus in the spinal cord-transected cat, all of 6 WDR neurons gave excitatory responses which were not depressed by 75% nitrous oxide. (2) When the injection of 10 micrograms of BK into the femoral artery ipsilateral to the recording site was used in the spinal cord-intact cat, 6 of 15 WDR neurons (40%) gave excitatory responses, which were significantly depressed by 75% nitrous oxide, and 9 of 15 WDR neurons (60%) gave inhibitory responses, which were not affected by 75% nitrous oxide. (3) When 10 micrograms of bradykinin (BK) was injected into the femoral artery contralateral to the recording site as the noxious test stimulus in the spinal cord transected cat, 6 of 12 WDR neurons gave excitatory reasons, which were not depressed by 75% nitrous oxide. (4) When the injection of 10 micrograms of BK into the femoral artery contralateral to the recording site was used in the spinal cord-intact cat, 6 of 6 WDR neurons (100%) gave responses, which were affected by 75% nitrous oxide. We have observed that nitrous oxide reduces the excitation and inhibition of dorsal born WDR neuronal activities induced by BK injection in spinal cord-intact cats, but does not reduce the excitation of those in spinal cord-transected cats. This finding confirmed that the antinociceptive effect of nitrous oxide might be modulated by supraspinal descending inhibitory control systems. In addition our result showed that the supraspinal effect of nitrous oxide was mediated not only by an increase but also a decrease in a supraspinal descending inhibition.     

Development of a micro optical diffusion sensor using laser‐induced dielectrophoretic manipulation

We have developed a novel micro optical diffusion sensor (MODS) based on laser‐induced dielectrophoresis (LIDEP), which enables rapid measurement with a small sample volume and on‐site sensing of protein conformation. This paper presents the measurement principle, the chip design, and the validity of the proposed method. To verify the applicability of MODS, we confirmed a sinusoidal concentration distribution of polystyrene beads in a surface‐modified microchannel generated by LIDEP force. The decay time of the diffusion of the concentration distribution agreed well with theoretical calculations, confirming the applicability of MODS as a technique for measuring the diffusion coefficient. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20303     

基于神经网络和相似搜索技术的电力价格钉预测方法

电力市场中普遍存在“价格钉”,其特殊性给电价预测带来困难。通过对其特征和影响因素的分析,提出了一种基于神经网络和相似搜索技术的价格钉预测方法。首先,采用BP神经网络建立价格钉识别模型,对未来某一交易时段市场清算电价可能出现的区间进行预测,并提供相应的置信度;其次,对判别为价格钉的时段采用相似搜索技术进行二次预测。采用澳大利亚昆士兰州电力市场2004年至2005年全年的电价数据进行训练和预测分析,结果验证了该方法的有效性。     

中国低活化马氏体钢CLAM研究进展

低活化铁素体/马氏体钢(RAFM钢)被普遍认为是未来聚变示范堆和聚变动力堆的首选结构材料。国际上给予了高度重视,许多国家都在研发其特有的RAFM钢。中科院等离子体物理研究所在与国内外多家单位的合作下发展了中国低活化马氏体钢———CLAM。本文总结了CLAM钢研制发展的主要进展,包括其成分优化设计、冶炼加工制备工艺、物理性能、机械性能、辐照性能及与液态LiPb的相容性等测试与研究以及各种焊接工艺研究等,并对今后的发展方向进行了展望。