Magnetic drive system for a new centrifugal rotary blood pump

The purpose of this investigation was to design a novel magnetic drive and bearing system for a new centrifugal rotary blood pump (CRBP). The drive system consists of two components: (i) permanent magnets within the impeller of the CRBP; and (ii) the driving electromagnets. Orientation of the magnets varies from axial through to 60° included out‐lean (conical configuration). Permanent magnets replace the electromagnet drive to allow easier characterization. The performance characteristics tested were the axial force of attraction between the stator and rotor at angles of rotational alignment, ?, and the corresponding torque at those angles. The drive components were tested for various magnetic cone angles, θ. The test was repeated for three backing conditions: (i) non‐backed; (ii) steel‐cupped; and (iii) steel plate back‐iron, performed on an Instron tensile testing machine. Experimental results were expanded upon through finite element and boundary element analysis (BEM). The force/torque characteristics were maximal for a 12‐magnet configuration at 0° cone angle with steel‐back iron (axial force = 60 N, torque = 0.375 Nm). BEM showed how introducing a cone angle increases the radial restoring force threefold while not compromising axial bearing force. Magnets in the drive system may be orientated not only to provide adequate coupling to drive the CRBP, but to provide significant axial and radial bearing forces capable of withstanding over 100 m/s² shock excitation on the impeller. Although the 12 magnet 0° (θ) configuration yielded the greatest force/torque characteristic, this was seen as potentially unattractive as this magnetic cone angle yielded poor radial restoring force characteristics.     

不同刺激间隔对全麻患者经颅磁刺激运动诱发电位监测的影响

目的 评价不同刺激间隔对全麻患者经颅磁刺激运动诱发电位（TMS-MEP）监测的影响。方法 择期脊髓手术患者20例，ASAⅠ或Ⅱ级，静脉注射异丙酚2mg／kg、芬太尼2μg，kg、氯化琥珀胆碱2mg／kg麻醉诱导，气管插管后机械通气，持续输注异丙酚5mg·kg^-1·h^-1、芬太尼1μg·kg^-1·h^-1维持麻醉至试验结束。在麻醉前、后分别记录2、5、10ms（分别为500、200、100Hz）刺激间隔下4次刺激引出的复合肌肉动作电位（CMAP）的波幅和潜伏期。结果 麻醉前：与2ms相比，5ms刺激间隔下CMAP波幅差异无统计学意义（P〉0．05），与2In8和5In8相比，10ms刺激间隔下CMAP波幅减小（P〈0．05）；麻醉后：与2ms相比，5、10ms刺激间隔下CMAP波幅减小（P〈0．05），与5ms相比，10ms刺激间隔下CMAP波幅减小（P〈0．05）。麻醉前、后各刺激间隔下CMAP潜伏期差异无统计学意义（P〉0．05）。麻醉后5ms刺激间隔下2例患者未记录到CMAP，10ms刺激间隔下4例患者未记录到CMAP。结论 采用2ms刺激间隔下对全麻患者4次经颅磁刺激可在靶肌肉上记录到最大的CMAP波幅，更适用于全麻患者术中施行经颅磁刺激运动诱发电位监测，可有效对抗异丙酚静脉麻醉对运动诱发电位的抑制作用，增加运动诱发电位监测的准确性。     

Effects of treadmill exercise on transcranial magnetic stimulation-induced excitability to quadriceps after stroke

OBJECTIVE: To determine characteristics of transcranial magnetic stimulation (TMS)-induced measures of central motor excitability to the paretic and nonparetic quadriceps muscles of chronic hemiparetic stroke patients in the context of a short-term, submaximal bout treadmill exercise. DESIGN: Cross-sectional. SETTING: Motor control and gait biomechanics laboratory. PARTICIPANTS: Convenience sample of 11 patients including cohorts of treadmill untrained (n=8) and trained (n=3) stroke patients with chronic hemiparetic gait. INTERVENTION: Short-term submaximal treadmill exercise. MAIN OUTCOME MEASURES: Thresholds, amplitudes and latencies of TMS-induced motor evoked potentials at vastus medialis in paretic and nonparetic lower extremities. RESULTS: Baseline characteristics of the motor evoked potentials (MEPs) show significantly higher motor thresholds, longer latencies, and reduced amplitudes on the paretic side. In cross-sectional comparisons a group of treadmill-trained patients had greater paretic MEP amplitude changes after treadmill exercise versus paretic MEP responses from a group of untrained patients. CONCLUSIONS: These results indicate that treadmill training for 3 months or more may alter responsiveness of the lower-extremity central motor pathways to a short-term treadmill stimulus.     

磁水对家兔睾丸生精功能的影响

用磁水饲养家兔，经3和6个月的观察，实验组动物 精液量、精子数、精子存活率，附睾尾中精子数以及每100mg附睾尾组织的精子烽，曲细精管直径及曲细精管生精细胞数都比对照组显著增加；精子畸形率比对照组明显减少，光镜及扫描电镜观察显示实验组精母细胞、精子细胞、精子数量都比对照组显著增加，表明饮用磁水能促进生精功能。     

恒定磁场治疗海绵状血管瘤64例

本文报导了恒定磁场治疗海绵状血管瘤64例,临床观察结果表明,有效率为95.31％,显效率(含基愈)为64.06％,并对显效以上的38例患者,进行了1～6年的随访观察,其疗效均巩固。     

用移植物细胞模型评价CD+34细胞选择的效果

目的用移植物细胞模型评价免疫磁珠法进行CD34阳性细胞选择的效果.方法用荧光素Calcein-AM标记靶细胞后分别种入细胞株、骨髓(BM)或外周血干(祖)细胞(PBSC)中以建立模型;用免疫磁珠法对模型进行CD34阳性细胞选择,以流式细胞仪(FCM)进行选择前后的效果评价.结果模型Ⅰ(靶细胞加细胞系)、Ⅱ(靶细胞加BM)、Ⅲ(靶细胞加PBSC)经选择后CD+34细胞纯度分别为(94.54±0.93)%、(68.15±23.53)%、(57.18±9.23)%;富集倍数分别为7.9±0.1、10.4±4.0、8.2±1.3;回收率分别为(27.6±3.8)%、(44.4±13.1)%、(66.4±13.9)%.模型Ⅱ中肿瘤细胞的清除率为(1.82±0.51)个对数级(log);模型Ⅲ中T细胞的清除率为(2.48±0.38)log.结论移植物细胞模型能简便、准确、快速地评价CD34阳性细胞选择时的富集和净化作用.免疫磁珠法进行CD34阳性选择具有良好的CD+34细胞富集效果及肿瘤细胞和T细胞的清除效率.     

表面磁性膜医用316L不锈钢支架对兔髂动脉内膜增殖的影响

目的 研究表面磁性膜医用316L不锈钢支架对新西兰大白兔髂动脉新生内膜增殖的影响.方法 通过动物体内支架植入,采用定量冠脉造影、光学显微镜图像技术观察不同支架对新生内膜增殖和再狭窄的影响.结果 与普通裸支架相比,表面磁性膜支架可以抑制支架植入后的新生内膜增殖和再狭窄,植入3月后应用表面磁性膜支架和普通裸支架的管腔面积分别为(2.78±0.40)mm2和(2.07±0.62)mm2,再狭窄率分别为3.3%和16.7%,且可能与磁场强度相关.结论 表面磁性膜支架对经皮冠状动脉介入治疗术后的再狭窄可能具有防治作用.     

培养人视网膜色素上皮细胞牵拉模型中细胞骨架的改变

目的研究培养人视网膜色素上皮细胞（RPE）受机械牵拉力后细胞骨架的变化。方法将胶原包被的磁珠悬液加入培养的人RPE细胞后孵育,洗去未结合的磁珠。在磁场垂直方向力作用下0、4、8、12和24h,以及加入细胞松弛素D（0．05mmol／L,25min）预处理后,用免疫荧光双标染色法着染细胞中的肌动蛋白和波形蛋白,并用激光共聚焦显微镜观察。结果机械牵拉作用4h后,人RPE细胞的形态和微丝的极性发生改变。肌动蛋白微丝的排列与受力方向一致。细胞骨架微丝表达主要在细胞核周及磁珠聚集处周围。而加入细胞松弛素D预处理的细胞,在8h时发生以上变化。结论机械牵拉可引起人RPE细胞骨架分布的改变,使其表现出肌细胞的某些生物学特征,这对细胞的移行和增生可能有促进作用。     

用电子散斑干涉技术作磁力扩弓效应的实验研究

目的:对利用钕铁硼永磁体制成的磁力扩弓装置扩大上颌后上颌复合体产生的瞬时初始生物力学效应进行研究。方法:选取一具年龄在12岁新鲜的人尸体头颅骨为实验对象,保持完整的上腭黏膜,保留颅颌骨缝间纤维及牙周膜。磁力扩弓分别在1、5、15、30、60min进行观察。使用电子散斑干涉仪测量扩弓后上颌骨表面的离面位移和变形,并与微机图象处理相结合。结果:整个上颌骨及其周围邻接骨,相应的牙齿显现出清晰的干涉条纹,随着时间的变化,在上颌复合体的不同部位所产生条纹的密度和形状均不相同。结论:磁力扩大上颌的初始应力效应主要传导在上颌复合体的深部结构上。     

磁性纳米粒子介导肿瘤核磁共振成像及热疗

磁性纳米粒子介导肿瘤治疗作为一种新型肿瘤治疗技术,推动肿瘤热疗向靶向定位和精确控制的方向发展.近年来研究学者们在对磁性纳米粒子的表面修饰、与放化疗的联合应用以及临床应用进行深入研究的同时,发现超顺磁性铁氧体纳米粒子经表面修饰获得水溶性后,可做核磁共振(MR)造影剂,这种集诊断与治疗于一体的磁性纳米粒子,将进一步推动磁性纳米粒子介导肿瘤治疗向更安全、有效的方向发展.