Immunomagnetic separation using carbonyl iron powder and flow cytometry for rapid detection of <Emphasis Type="Italic">Flavobacterium psychrophilum</Emphasis>

Bacterial cold water disease, caused by Flavobacterium psychrophilum, is a serious problem in the aquaculture industry worldwide. Several methods to prevent and treat cold water disease have been studied. Although detection at the early stage of F. psychrophilum infection is very important for the prevention and treatment of cold water disease, an effective detection method has not yet been developed. The use of flow cytometry (FCM) for the rapid determination of bacterial cell numbers with high sensitivity is beginning to attract attention. Immunomagnetic separation (IMS) has also been used to detect F. psychrophilum. The purpose of the present study was to develop a method to quickly determine the number of bacterial cells by combining the FCM and IMS methods. Because samples can be more effectively concentrated using smaller magnetic beads and stronger magnetism, we used carbonyl iron powder as the magnetic beads for the IMS. The detection level of F. psychrophilum using FCM combined with IMS was 5 orders lower than that using FCM without IMS. The values determined using FCM combined with IMS strongly correlated with those obtained using the colony-counting method, in the range of approximately 10–10⁸ colony-forming units per milliliter. One FCM assay could be completed within 60 s and the total assay time, including sample preparation, was less than 2 h. The combined method of FCM with IMS developed in this study can be used reliably for the rapid detection of F. psychrophilum.     

Multifunctional Helicene-Based Ytterbium Coordination Polymer Displaying Circularly Polarized Luminescence,Slow Magnetic Relaxation and Room Temperature Magneto-Chiral Dichroism**

The combination of physical properties sensitive to molecular chirality in a single system allows the observation of fascinating phenomena such as magneto-chiral dichroism (MChD) and circularly polarized luminescence (CPL) having potential applications for optical data readout and display technology. Homochiral monodimensional coordination polymers of Yb^III were designed from a 2,15-bis-ethynyl-hexahelicenic scaffold decorated with two terminal 4-pyridyl units. Thanks to the coordination of the chiral organic chromophore to Yb(hfac)₃ units (hfac⁻=1,1,1,5,5,5-hexafluoroacetylaconate), efficient NIR-CPL activity is observed. Moreover, the specific crystal field around the Yb^III induces a strong magnetic anisotropy which leads to a single-molecule magnet (SMM) behaviour and a remarkable room temperature MChD. The MChD-structural correlation is supported by computational investigations.     

Optimal brushless DC motor design using genetic algorithms

This paper presents a method for the optimal design of a slotless permanent magnet brushless DC (BLDC) motor with surface mounted magnets using a genetic algorithm. Characteristics of the motor are expressed as functions of motor geometries. The objective function is a combination of losses, volume and cost to be minimized simultaneously. Electrical and mechanical requirements (i.e. voltage, torque and speed) and other limitations (e.g. upper and lower limits of the motor geometries) are cast into constraints of the optimization problem. One sample case is used to illustrate the design and optimization technique.     

Energy efficient iron based electronic field cycling magnet

A new concept for an energy efficient electromagnet for fast field cycling NMR applications as well as its construction and first test results are presented. The magnet, which provides a rectangular sample space of 17 × 25 mm, has an iron yoke and pole pieces optimised with respect to the B₀ homogeneity. The maximum field is 0.66 T at a current of 320 A; its field inhomogeneity for a cylindrical sample (length 7 mm, diameter 6 mm) is about 50 ppm. The power dissipation during polarisation at 0.55 T is as low as 1.4 kW. The magnet is powered by a commercially available power supply and can be rapidly switched with a slew rate of 0.55 T/ms. The system has shown a stability of 50 ppm/h.     

单块磁悬浮系统磁体和超导体的厚度优化

研究了磁铁厚度和YBCO超导体厚度对悬浮力的大小及系统动态特性的影响,通过分析得出磁悬浮系统中磁体和超导体厚度的最优值。通过悬浮力测试系统测得超导块尺寸为φ30mm×18mm时四块不同厚度的磁体的悬浮力以及磁体尺寸为φ30mm×10mm时六块不同厚度的YBCO超导体的悬浮力的大小;并在振动实验台上测试了上述情况下的振动特性。对动态曲线进行频谱分析,最终得出最优组合,从而对磁悬浮系统的磁体和超导体厚度进行了优化。     

合肥同步辐射光源波动器UD-1物理设计

 介绍了国家同步辐射实验室二期工程新建波动器UD-1的物理设计，给出了设计参数和主要技术要求。从储存环电子束流的要求和用户对光源的要求两方面分析了波动器磁场品质应满足的技术指标，给出UD 1的磁场一次积分值应小于2×10^-4T·m，二次积分值应小于2×10^-4T·m ²,相位误差应小于10°。     

Bi-2212超导线材研究进展

Bi-2212高温超导材料在高磁场中具有优异的磁场载流能力,可制备成各向同性圆线,可以绞制成大电流的电缆导体,是大型强磁场磁体的首选材料之一。经过30多年的发展,Bi-2212超导线材的临界工程电流密度(J_E)也已达到工程应用要求。综述了国内外近年来Bi-2212超导材料在载流性能、绝缘、内插线圈和热处理等方面的研究进展。     

高场超导磁体科学技术与应用

科学技术的发展对于磁场强度质量的要求越来越高,极端强磁场条件是人类追求的永远的科学目标,它孕育着许多重大的科学发现和新技术的产生,对人类的科学和技术以及生活产生重大的影响.以磁体为核心与电力电子器件以及相关的软件等结合可以构成各种各样科学仪器和装置,广泛应用在科学研究和工业特种装备中.磁技术对于人类的科学与技术进步起到越来越重要的作用,尤其是极高磁场所带来的诸多优点,使得人类对于物质世界认识不断加深,对于生命的起源以及从事疾病的防治的研究有特别重要的意义.本文介绍磁体基本原理、磁场产生的方法与应用以及相关的发展.     

GSI收集环二极磁体稳定性分析

收集环二极磁体在探测反质子和离子加速器装置中有着重要的作用.在本文中,通过对收集环二极磁体的绝热理论分析,得出其稳定性参数与运行电流之间的关系.另外运用Miils方程计算得出失超后收集环二极磁体内导体温度与时间的对应关系.     

Interacting Stoner–Wohlfarth behavior in hysteresis curves of Sm(CoFeCuZr)z magnets

Several magnets with different Zr contents were studied: Sm(Co_balFe_0.2Cu_0.1Zr_x)₈ (bal=balance; x=0, 0.02, 0.04, 0.06 and 0.08). The microstructure of the magnets includes three main phases, all crystallographically coherent: the cell phase Sm₂(Co,Fe)₁₇, the cell boundary phase Sm(Co,Cu)₅ and a lamellar Zr-rich phase, rhombohedral (ZrSm)₁Co₃. The hysteresis curves were compared with the Callen, Liu and Cullen (CLC) modification of the Stoner–Wohlfarth model for an isotropic distribution of interacting single-domain particles. Choosing reasonable values for the saturation magnetization M_s, the anisotropy field H_a, and the mean-field interactions of the CLC model, we were able to reproduce the main features of the hysteresis curves for the x=0.02 and 0.04 samples. For higher x values, X-ray diffraction Rietveld analysis revealed the presence of other “impurity” phases, among them cubic Zr₆(Co,Fe)₂₃, rhombohedral (SmZr)₅(CoFeCu)₁₉ and rhombohedral (SmZr)₂(CoFeCu)₇.