Reversible control of magnetic and transport properties of NdNiO3-δepitaxial films

Rare-earth nickelates possess intrinsic charge order,orbital order,and electron-lattice coupling,which make them very interesting for applications in oxide-based electronic devices.In this study,we grew NdNiO_3-δ(NNO) films with oxygen pressures changing from 27 to 10^-5 Pa.With decreasing oxygen pressure,the antiferromagnetic state of the NNO film becomes a ferromagnetic state,and the resistance increases significantly.According to combined X-ray absorption spectro scopy and X-ray linear dichroism measurements,the ratio of Ni²⁺-ions increases with decreasing oxygen-pressure,and the preferred orbital occupation changes from x²-y² to 3 z²-r².In addition,using the ionic-liquid gating method to control the migration of oxygen vacancies,both the magnetic properties and resistance of NNO films can be modulated reversibly.The oxygen vacancy induces a valence in the Ni ions and the orbital occupation changes,which alters the magnetic properties and the electronic transport in these NNO films.This study describes a novel tunable method for electronic devices that use NdNiO_3-δ films,and opens new doors for future improvements and functionalities.     

PLC在SLon系列磁选机的应用

SLon系列磁选机是运用开发细粒弱磁性矿物选矿新技术而研制的高梯度先进磁选设备。采用基于西门子公司的S7-200 PLC和Smart 700 IE触摸屏控制结构设计的SLon磁选机控制系统,对主要控制参数-励磁电流采用PID控制算法,实现对磁选机系统的最优控制。该控制系统通过温度变送器、电流变送器、电压变送器将可控硅元件的温度、励磁电流和电压转换成0-5 V的电压或4-20 mA的电流送入PLC的控制器模块,通过设计PID控制算法,控制可控硅数字触发装置,精确地调整可控硅触发时的开通角,使可控硅元件工作在允许的温度条件下,输出稳定的励磁电流。     

Heredity of Aluminum Melt by Electric Pulse Modification (Ⅱ)

 Heredity of high pure aluminum melts under different pulse electric field was investigated by means of repetitious remelt experiment. The results indicate that the genetic coefficient by measurement of grain size of cast structure has a close relation with pulse voltage. Moreover, the hereditary law accords with the function of In=1+e-αn+β. The stability of genetic carrier (cluster) comprises in the competition between repetitious cooling and heating impulse and the effect of electric pulse modification.     

电子高压脉冲轨道电路的研制与应用

简要介绍铁路运输远程自控系统中主要设备轨道电路原采用ＪＺＸＣ－４８０型存在的问题,详细研究分析电子高压脉冲轨道电路的原理、特性和测试方法,并提出安装维护技术指标。     

Heat transfer evaluation of the nasal thermistor technique

When analyzing transvalvular and venous flow velocity patterns, it is important to relate them to respiration. An accurate recording of respiratory phase can be carried out with different methods. One of these methods is the use of a thermistor, which reacts to the variation in air temperature, placed in the noise of the patient. The thermistor used has a diameter for 1.0 mm and is of standard bead type. Although small, it has a considerable long time-constant and a long time-delay. The high time-constant gives a low cutoff frequency, well below the respiratory frequency and thereby causing a large phase difference. The thermistor was analyzed with the lumped heat capacity method, where it was easy to study the influence from design parameters, time-dependent air temperature, and velocity. The analysis was extended using the finite element method and the temperature field in the thermistor and the probe was calculated as a function of space and time. These calculations confirmed the result from the lumped model. The result showed that timing of respiration was not accurately obtained with the thermistor analyzed. To improve the timing, it was necessary either to change the measuring method or to use signal processing in order to achieve faster response.     

Heredity of Aluminum Melt by Electric Pulse Modification (II)

Heredity of high pure aluminum melts under different pulse electric field was investigated by means of repetitious remelt experiment. The results indicate that the genetic coefficient by measurement of grain size of cast structure has a close relation with pulse voltage. Moreover, the hereditary law accords with the function of I_n = 1 + e^−αn+β. The stability of genetic carrier (cluster) comprises in the competition between repetitious cooling and heating impulse and the effect of electric pulse modification.     

高压电力电缆故障点查找定位

在原有低压脉冲显示设备的基础上，改低压脉冲返回信号为用高压直流放电返回信号，可以得到直观，无干扰的波形，采用高压直闪电缆故障定点法替代原低压脉冲法，能够准确，快速地查找高压电力电缆故障。     

Influence of the Magnetic Field on the Crystallization of Aluminum Melts

In order to control the crystallization of metals consciously with the purpose of forming the specified ingot microstructure, various physical fields are used. They vary the internal state of the melt and, consequently, the crystallization kinetics when affecting the melt. In this article, the thermodynamic and kinetics of the crystallization of aluminum under melt processing with the magnetic field is described. A rather simple experimental setup which makes it possible to investigate the magnetic-field effect on the melts of aluminum or other metals and alloys is designed. It consists of several main units: (1) the electrical furnace, (2) the water-cooled copper crystallizer combined with an electromagnetic coil, (3) mechanical facility for the rapid motion of a crucible with the aluminum melt, (4) the monitoring and control system of the melt temperature, and (5) the electronic part for recording and processing information. It is established experimentally that the magnetic field varies the temperature of the melt–crystal phase equilibrium, latent heat of the phase transition, and supercooling temperature of the melt during crystallization. It is shown that the variation in these parameters leads to a decrease in the radius of critical nuclei and an increase in their nucleation rate. The temperature–temporal dependences of crystallization are found. It is established experimentally that the crystallization time shortens under the aluminum melt treatment with the magnetic field. The analysis of aluminum samples formed under the magnetic-field effect showed that their structure is finer grained when compared with the samples not subjected to such treatment.     

氧氮分析仪的热导检测器及热敏元件选择

讨论了金属中氧氮分析仪所用热导检测器及其核心热敏元件的选择。基于NTC热敏电阻阻值大,所需桥流小,且元件采用惰气保护密闭封装,能够抵御恶劣的环境条件,很好地保持热导检测器测量电桥的对称性、稳定性,具有应用灵活、简单的特点,选择NTC热敏电阻作为热导检测器的热敏元件,并应用于金属中氧氮分析仪,其线性和灵敏度均符合仪器使用和分析要求。采用NTC热敏电阻作为热敏元件、选择扩散型热导池结构研制的热导检测器应用于ON-2008氧氮分析仪中。分别采用高含量和低含量氮的标准物质对仪器的高氮和低氮两个测量通道的线性和精密     

合金碳化物M23 C6的磁性及磁致磁性

利用第一性原理研究了碳化物M23 C6 (M=Fe,Cr)的晶胞结构、磁矩和态密度,并结合魏氏分子场理论分析了磁场作用下一些碳化物的磁致磁性.结果 显示:Fe20 Cr3 C6碳化物中的Fe3和Fe4原子连接组成稳定的晶格框架,Cr1、Cr2和C原子位于框架中心;Fe20 Cr3 C6的磁性主要来源于Fe和Cr原子的3...     

Transparent perovskite glass-ceramics for visual optical thermometry

Optical thermometers have aroused considerable attention in recent years,and the increasing demand of sensitivity for practical application encourages the investigation on developing innovative non-contact optical thermo metric materials with higher sensitivity and accuracy.Perovskite quantum dots(QDs)with excellent temperature-dependence optical properties,provide a feasible approach to realizing the detection of temperature change,however,their poor high temperature thermal stability and the facile realization to obtain the production remain a daunting challenge.Herein,growing Tb~(3+)-doped CsPbl_3 QDs in situ in borosilicate glass is proposed,which ensures the phase stability,and high-efficiency florescence output of the all-inorganic perovskite as a temperature sensor.A higher absolute and relative temperature sensitivity(0.0398 K~(-1) and 7.12%/K,respectively),along with the visible color change from orange-red to yellow-green with the increase of temperature is accomplished.Notably,the repeatable florescence intensity of Tb~(3+)-doped CsPbl_3 QDs under high temperature enables their temperature sensing application.     

柜式高压热变电阻器在高压电机软起动中的应用

介绍了东北特钢集团(大连基地)煤气车间柜式高压热变电阻器在450kW高压异步电动机起动中的应用情况。通过采用该种软起动方式,降低了电机起动发热,减少了对机械设备的冲击,有效延长了电机使用寿命,并且减少了起动时对电网的冲击,保证了煤气加压机安全稳定运行。     

降低铝电解槽焦粒焙烧冲击电压的试验研究

分析了预焙铝电解槽焦粒焙烧启动过程中造成冲击电压高的原因及不利影响,进行了降低焙烧通电冲击电压的试验研究。研究结果表明,改进焦粒的组成、用焦粒筛铺设焦粒以及通电初期电流合理分流,可降低焙烧冲击电压,提高电解槽焙烧质量。     

钴在提高钕铁硼合金居里温度和降低温度系数中的作用

本研究通过添加钴和其它微量元素,使钕铁硼永磁合金的居里温度提高,温度系数降低;并在改善合金温度稳定性的同时,使之仍保持高的磁性能。所制合金具有下述良好性能:Br=1.29T;iHc=648kA/m;bHc=584kA/m;(BH)_max=304kJ/m3;Tc=500℃;α_Br=0.015%/℃。     

Overview of Recent Progress in Sm-Co Based Magnets

Superior magnetic properties of Sm-Co based magnets, especially their excellent high temperature stability and low temperature coefficient, have led to an exciting variety of applications. Despite the commercial success of sintered Nd-Fe-B magnets, Sm-Co magnets continue to play a dominant role in some critical applications, such as traveling wave tubes (TWT) for space exploration and satellite communication; inertial devices for accelerometers and gyroscopes; power tools for medical applications; and permanent magnet motors and generators for aircraft engines. We will review the recent development in ultra-high temperature magnets and zero RTC (reversible temperature coefficient) magnets.     

Diagnostic delay and related factors in women with breast cancer

Experiments were undertaken in order to verify whether or not a strong magnetic field would have any biological effects on the cell growth, viability and radiation response of mammalian cells. Magnetic field exposures were conducted using a superconducting magnet with freshly-isolated human peripheral blood T-lymphocytes maintained at their normal growing temperature of 37 degrees C. The static magnetic fields with intensities up to 6.3-tesla (T) exerted little influence on the cell growth and viability of actively-growing T-lymphocytes under normal cell-culture conditions. On the other hand, the T cells exposed to the magnetic fields (4 T-6.3 T) during PHA stimulation were inhibited in their cell growth when compared to controls. The effects of the magnetic fields with intensities up to 2 T on cell growth properties, however, were minimal in this system. Also, the radiosensitivity of T-lymphocytes previously exposed to the strong magnetic fields was more sensitive than that of control cells. These results suggest that exposure to a static magnetic field of 4 T or stronger might lead to physiological and growth abnormalities at the cellular level.     

Detection of respiratory events during NPSG: nasal cannula/pressure sensor versus thermistor

Recording of respiratory airflow is an integral part of polysomnography (NPSG). It is conventionally monitored with a thermistor that measures temperature as a surrogate of flow. The subjectivity of interpreting hypopnea from this signal has prompted us to measure nasal airflow directly with a simple pneumotachograph consisting of a standard nasal cannula connected to a 2-cm H2O pressure transducer. We manually analyzed respiratory events using simultaneous thermistor and nasal cannula in 11 patients with obstructive sleep apnea syndrome (OSAS) and 9 with upper airway resistance syndrome (UARS). Definite events were scored separately for each signal when amplitude was <50% for >10 seconds. Events were also scored on the nasal cannula signal when the flattened shape of the signal suggested flow limitation, and these were tabulated separately. Definite events in one signal were tabulated by whether the other signal showed a definite event or not. In addition, nasal cannula events were compared to a more liberal thermistor criterion (any change in the signal for > or = 2 breaths). Visually, events were more easily recognized on the nasal cannula signal than on the thermistor signal. In OSAS, 1,873 definite thermistor events were detected. Of these, 99.1% were detected by nasal cannula, and 0.9% were missed. Of 3,541 definite nasal cannula events, 51.9% were detected by definite thermistor criteria; 75.0% were detected by liberal thermistor criteria; 25.0% were missed. In UARS, 123 definite thermistor events were detected. Of these, 89.4% were detected by nasal cannula and 10.6% were missed. Nine hundred and three nasal cannula events were detected. However, only 17.2% of these were detected by definite thermistor criteria; 38.6% were detected by liberal thermistor criteria; 61.4% were completely undetected by thermistor. When events identified on the nasal cannula by flow limitation alone were excluded, the thermistor detected 30.1% of events by definite criteria and 78.6% by liberal criteria, still leaving 21.4% completely undetected by the thermistor. We conclude that the nasal cannula reliably detects respiratory events seen by thermistor. Additional events (including some characterized only by flow limitation) that help define the UARS, were recognized by nasal cannula but often completely missed by thermistor. We propose that respiratory monitoring during NPSG with nasal cannula significantly improves event detection and classification over that with thermistor.     

双流法溶出新工艺高温碱液腐蚀与防止方法试验研究

本文报导了国家攻关项目———双流法溶出新工艺及设备研究专题中高温碱液预热器工业模拟腐蚀试验和工业腐蚀试验结果。通过分析工业腐蚀试验中高温碱液预热器的温度径向分布,得出在预热器内套管内壁处碱液因饱和蒸气压大于其静压力产生气泡,气泡因压力梯度和温度梯度的存在,在向径向移动的过程中冷却破裂,对其内壁产生巨大冲击力而发生腐蚀,即空泡腐蚀;提出了应用双流法改进流程、降低熔盐温度、提高碱液与矿浆流的比例和采用全逆流预热流程等防止腐蚀方法。通过调整工艺条件和设备参数,应用双流法溶出新工艺稳定运行800多小时,无腐蚀现象发生。     

Irradiation Behavior in High Entropy Alloys

As an increasing demand of advanced nuclear fission reactors and fusion facilities,the key requirements for the materials used in advanced nuclear systems should encompass superior high temperature property,good behavior in corrosive environment,and high irradiation resistance,etc.Recently,it was found that some selected high entropy alloys(HEAs) possess excellent mechanical properties at high temperature,high corrosion resistance,and no grain coarsening and self-healing ability under irradiation,especially,the exceptional structural stability and lower irradiation-induced volume swelling,compared with other conventional materials.Thus,HEAs have been considered as the potential nuclear materials used for future fission or fusion reactors,which are designed to operate at higher temperatures and higher radiation doses up to several hundreds of displacement per atom(dpa).An insight into the irradiation behavior of HEAs was given,including fundamental researches to investigate the irradiation-induced phase crystal structure change and volume swelling in HEAs.In summary,a brief overview of the irradiation behavior in HEAs was made and the irradiation-induced structural change in HEAs may be relatively insensitive because of their special structures.     

强磁场对铁基合金相变温度和显微组织的影响

The effect of a high magnetic field up to 30 T on phase transformation temperature and microstructure of Fe-based alloys has been reviewed. A high magnetic field accelerates ferrite transformation, changes the morphology of the transformed microstructures and increases the As and A1 temperature. In a magnetic field of 30 T, the A1 temperature increases by about 37.1℃ for Fe-0.8C, the A3 temperature for pure Fe increases by about 33.1 ℃. The measured transformation temperature data are not consistent with calculation results using Weiss molecular field theory. Ferrite grains are elongated and aligned along the direction of magnetic field in Fe-0.4C and Fe-0.6C alloys by ferrite transformation, but elongated and aligned structure was not found in pure Fe, Fe-0.05C alloy and Fe-1.5Mn0.11C-0.1V alloy.