Effect of induced shielding current transmission in longitudinal direction on levitation force of melt grown single-domain YBa_2Cu_3O_(7-x) cylindrical superconductor

YBa2Cu3O7-x (YBCO) bulk is one of the most important high temperature superconducting materials for magnetic levitation applications, because it has a high magnetic irreversibility field Hirr at liquid nitrogen temperature, and can grow into large grains. The levitation force of YBCO bulk is proportional to the critical current density (Jc) and grain radius (r)[1], so higher Jc and r are appreciated for YBCO bulks to achieve higher levitation force. Now single-domain YBCO bulks up to s…     

超高效液相色谱-串联质谱法快速同时测定生姜中10种营养成分

建立了超高效液相色谱-串联质谱（UHPLC-MS/MS）快速同时测定生姜中姜辣素类和姜黄素类营养成分的分析方法，具体包括6-姜酚、8-姜酚、10-姜酚、6-姜烯酚、8-姜烯酚、10-姜烯酚、四氢姜黄素、姜黄素、去甲氧基姜黄素、双去甲氧基姜黄素10种目标物。采用ZORBAX RRHD Eclipse Plus C18色谱柱（100 mm×2.1 mm，1.8 μm）分离，以0.1%（v/v）甲酸水溶液和0.1%（v/v）甲酸甲醇溶液为流动相进行梯度洗脱，采用电喷雾电离（ESI）源、正离子和多反应监测（MRM）模式对目标物进行定性确证和定量分析。10种营养成分的线性相关系数（r）均≥ 0.9995，方法的定量限为0.10~7.71 μg/L，样品基质在3个水平下的平均加标回收率为82.8%~115.3%，相对标准偏差（RSD）为0.58%~11.49%。分析结果显示，生姜中10种营养成分均有检出，其中6-姜酚的含量最高且集中分布于373.35~702.48 mg/kg。该法简便快速，准确可靠，适用于生姜中姜辣素类和姜黄素类营养成分的分析，可为生姜质量鉴定和控制提供技术手段。     

共固定化IFN-α和IFN-γ的抗宫颈癌作用

干扰素(Ⅰ型、Ⅱ型)是具有抗肿瘤作用的蛋白质型的细胞因子，与4-叠氮苯甲酸反应，经红外光谱确认生成物在约2118cm^-1处有叠氮基团的典型吸收，证明合成得到了光活性的干扰素。采用光固定法将光活性蛋白质固定到24孔组织培养聚苯乙烯板上，制成生物材料。实验通过扫描电子显微镜(SEM)，时光固定化细胞因子的微观形态进行观察。通过做细胞生长曲线，透射电镜观察两种细胞因子固定化抑制宫颈癌细胞生长、诱导细胞凋亡的情况。实验表明，共固定IFN-α和IFN-γ，能有效地抑制宫颈癌细胞的生长，在低剂量(60ng／孔)的情况下，抑制活性达到70％，而IFN-γ，具有明显的协同抑癌作用。     

β-Cyclodextrin-Bonded Chiral Stationary Phase for Thin-Layer Chromatographic Separation of Enantiomers

JPC – Journal of Planar Chromatography – Modern TLC -     

Effect of induced shielding current transmission in longitudinal direction on levitation force of melt grown single-domain YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7−<Emphasis Type="Italic">x</Emphasis></Subscript> cylindrical superconductor

A novel layer deletion method is used to experimentally investigate the effect of induced shielding current transmission (ISCT) in the longitudinal direction on the levitation force of a single-domain YBa₂Cu₃O_7−x (YBCO) cylindrical superconductor (ϕ30×7 mm). In the experiment the sample was gradually sliced into two equal sheets, at the middle height along a diameter with 5 mm every step. The experimental results show that the levitation force is closely related with the ISCT in the longitudinal direction. Any layer deletion, even a small piece of layer deletion can reduce the levitation force of the sample. After the whole layer was deleted the levitation force can diminish about 50%. It is also found that the levitation force is directly proportional to the effective factor of surface area, which is equal to the top surface area divided by the total surface area parallel to the top surface of the sample.     

低损耗NbTi线材制备技术研究

国内重离子加速器(HIAF)磁体服役在高速脉冲电流下,要求超导磁体用超导线具有较低的损耗,并具有高的临界电流,针对磁体的设计要求,本文研制了两种新型结构的NbTi/Cu0.5Mn超导线,通过两次组装、冷拉拔获得了线径Φ0.8mm、12960芯和10800芯、铜比2.0、芯丝小于5μm的高临界电流、低损耗超导线,系统研究了两种新型结构超导线的截面形貌、芯丝形貌、磁滞损耗及不同时效热处理次数超导线的临界电流密度(Jc)和n值,最后获得了线材芯丝直径和磁滞损耗的变化关系.研究结果表明,两种线材经过二次组装、挤压和冷拉拔后,单个亚组元成型良好,芯丝变形粗细均匀,尺寸大约4μm.随着时效热处理次数由3次增加到5次,线材芯丝表面有颗粒状的CuTi化合物生成,且5T、4.2K下临界电流密度由2295A/mm2增加到2958A/mm2,不同时效热处理次数的线材n值大小介于30~60之间,表明芯丝整体变形均匀.线径Φ0.8 mm、12960芯和10800芯线材在4.2K、±3T下的磁滞损耗分别为35.5mJ/cm3、42.8mJ/cm3,随着线材芯丝直径由4.6μm减小至2.8μm,磁滞损耗由42.8mJ/cm3降低至17.3 mJ/cm3.最后,通过优化工艺后获得了Jc(5T、4.2K)为2958 A/mm2,Qh(4.2K,±3T)为37.5mJ/cm3的千米级NbTi/Cu0.5Mn超导长线,并可实现批量化生产.     

Interfilamentary coupling properties of Bi2223/Ag tapes with oxide barriers subjected to AC perpendicular magnetic field

In this paper, we fabricated Bi2223 tapes with interfilamentary oxide barriers and evaluated interfilamentary coupling properties under an AC perpendicular magnetic field at 77 K. To avoid the side effect on Bi2223 phase formation during sintering process, SrZrO₃ was selected for barrier materials. Moreover, 20 wt.% Bi2212 was mixed with SrZrO₃ to improve its ductility for cold working. Monocore Ag-sheathed rods were coated by the oxide barriers with slurry before stacking with a honeycomb structure. By twisting the filament with twist pitch length below 10 mm and introducing interfilamentary barriers, the coupling frequency (f_c) under an AC perpendicular field, which is inversely proportional to the decay time constant (τ_c) of coupling current, exceeded 100 Hz. At perpendicular field amplitude above full-penetration field, the magnetization losses of the twisted barrier tape were reduced by 30–40% around power-grid frequency, compared with analytical values for fully-coupled filaments. However, the loss values were still considerably higher than the prediction of the hysteresis loss (Q_h) for the completely decoupled filaments. From the frequency dependence of losses, it was suggested that the loss reduction of twisted barrier tape around power-grid frequency were limited by not only the contribution of coupling current loss (Q_c) but also the insufficient Q_h reduction due to the presence of physical connection among the filaments positioned near the center of a tape section.     

高温超导体中的交流损耗

考虑到陶瓷高温超导体的颗粒物性 ,详细研究了 Bean- london模型及 Anderson- kim模型在分析高温超导体交流损耗方面的缺陷 ,提出了一种新的计算方法。用这种方法预期的损耗规律与文献报道的实验结果一致。另外 ,分析了超导体尺寸、晶间临界电流、晶粒尺寸和晶内临界电流对高温超导体交流损耗的影响     

Effect of excess Y_2O_3 addition on the physical properties of melt processed YBCO bulks

SincethediscoveryofhighTctemperaturesuperconductors,greatprogresshasbeenmadeinbothfundamentalresearchandpracticalapplications.Well-texturedYBCO[1—4]isoneofthemostimportantandpracticalhightemperaturesuperconductorsduetoitshighTcandhighJcinmagneticfield,especiallythehighlevitationforce,whichmakesitsapplicationspossible,suchasinmagneticbearing[5,6],flywheel[7—12],nocontactmagneticlevitationtransportsystem[13,14]andmotors[15,16].Itiswellknownthattheadditionof211to123makesonlyaslightdifferencei…     

Effect of excess Y<Subscript>2</Subscript>O<Subscript>3</Subscript> addition on the physical properties of melt processed YBCO bulks

The YBCO superconductors with Y₂O₃ addition were prepared by a modified melt textured process and the effects of excess Y₂O₃ addition on the physical properties of melt textured YBCO have been investigated. It is found that the melt temperature of YBCO samples decreases drastically with the increasing Y₂O₃, and the maximum levitation forces are drastically different for samples with different Y₂O₃ addition. It is also found that the optimal Y₂O₃ addition to YBCO is about 10wt%. Considering the microstructure and the starting composition, the results are well discussed and interpreted.