The pulsed high magnetic field facility and scientific research at Wuhan National High Magnetic Field Center

Wuhan National High Magnetic Field Center(WHMFC)at Huazhong University of Science and Technology is one of the top-class research centers in the world,which can offer pulsed fields up to 90.6 T with different field waveforms for scientific research and has passed the final evaluation of the Chinese government in 2014.This paper will give a brief introduction of the facility and the development status of pulsed magnetic fields research at WHMFC.In addition,it will describe the application development of pulsed magnetic fields in both scientific and industrial research.

Pulsed-field nuclear magnetic resonance:Status and prospects

High-magnetic-field nuclear magnetic resonance(NMR)has manifested itself as an indispensable tool in modern scientific research in the fields of physics,chemistry,materials science,biology,and medicine,among others,owing to its great advantages in both measurement sensitivity and quantum controllability.At present,the use of pulsed fields is the only controllable and nondestructive way to generate high magnetic fields of up to 100 T.NMRcombined with pulsed fields is therefore considered to have immense potential for application in multiple scientific and technical disciplines.Irrespective of the paramount technical challenges,including short duration of the pulsed fields,unstable plateaus,and poor field homogeneity and reproducibility,great progress has been made in a number of pulsed-field laboratories in Germany,France,and Japan.In this paper,we briefly review the status of the pulsed-field NMR technique,as well as its applications in multiple disciplines.We also discuss future trends with regard to the upgrading of pulsed-field NMR.

Realisation of the reconfigurable pulsed high magnetic field facility and its scientific application at Wuhan National Pulsed High Magnetic Field Centre

To generate arbitrary shape magnetic field waveforms for advanced scientific research,a reconfigurable pulsed high magnetic field facility(PHMFF)was developed at Wuhan National Pulsed High Magnetic Field Centre(WHMFC).First,the basic elements of PHMFF are introduced,and a ternary physical model composed of energy storage unit,magnet,transmission circuits and other auxiliary units is summarised to describe various magnetic field systems.Second,in order to realise the reconfiguration of magnetic field systems based on detailed elements,the control system with the ability of dynamic construction and control sequence reconfiguration is designed.On this basis,the PHMFF has been realised and various magnetic field systems are constructed to produce arbitrary shape magnetic field waveforms,such as half‐sine,ultra‐high,flat‐top and repetitive field pulses,which not only enhances the capability and efficiency of PHMFF,but also makes more scientific research possible in pulsed magnetic fields.So far,a peak magnetic field of 94.8 T,a flat‐top magnetic field of 64 T/10 ms and a repetitive magnetic field waveform of 20 T/60 Hz have been achieved,and some experiments and studies on the physical properties of materials have been carried out at WHMFC.

地衣芽孢杆菌类细菌素的分离、鉴定及其原核表达

目前,我国饲料中全面禁止添加抗生素,寻找新型的抗生素替代物成为科学研究的热点之一。为获得新的细菌素,本研究以大肠杆菌、沙门氏菌、金黄色葡萄球菌、表皮葡萄球菌、藤黄微球菌和单增李斯特氏菌为指示菌,通过牛津杯扩散法从羊驼粪便中筛选到高产抑菌物质的芽孢杆菌。基于菌落特征、革兰氏染色和16S rRNA的鉴定结果,将分离到的产抑菌物质菌株命名为地衣芽孢杆菌SXAU06株。采用硫酸铵沉淀、氯仿抽提、分子截留和SDS-PAGE等技术对所产抑菌物质进行分离纯化,经LC-MS/MS和生物信息学分析发现,抑菌物质为分子量约14 kDa的类细菌素,将其命名为BLISSXAU06。耐受性试验结果显示,BLISSXAU06具有耐高温、耐酸碱和耐蛋白酶K的特性。利用大肠杆菌表达系统对BLISSXAU06进行重组表达,所获得的重组BLISSXAU06具有抑制金黄色葡萄球菌、表皮葡萄球菌、藤黄微球菌和单增李斯特氏菌生长的活性。综上所述,BLISSXAU06具有优良的特性,可进一步在农业生产、生物医药和食品加工领域开展研究。

The importance of coil conductivity and eddy current effects in the analysis of electromagnetic forming process

Coil design and performance analysis are critical for the electromagnetic forming(EMF)process.However,previous studies have paid little attention to the coil con-ductivity,and the influence of eddy current effects in coil conductors on the forming process has not been well understood.This work aims to address these problems through numerical and experimental investigations.It is found that,due to the eddy current effects,the uneven current distribution appears in the coil conductors that should be considered when analysing the forming process,especially for the cases with large heights of coil conductors.Meanwhile,an important and interesting discovery is that the eddy current effects can greatly reduce the sensitivity of the coil conductivity with respect to the workpiece deformation,the Joule heating and the temperature rise in the coil.For instance,compared to a forming system with a copper coil,the forming height of the workpiece in the forming system with an AA5083‐O coil is reduced by less than 5%under the same discharge energy,while the copper conductivity is 3.3 times that of the latter.These results are helpful to understand the EMF process and achieve the optimal design of coils.