The differential effects of PNF versus passive stretch conditioning on neuromuscular performance

Abstract

The effects of flexibility conditioning on neuromuscular and sensorimotor performance were assessed near to full knee extension (25°). Eighteen males who were randomly assigned into two groups underwent eight weeks (three-times per week) of flexibility conditioning (hip region/knee flexor musculature; dominant limb) involving either proprioceptive neuromuscular facilitation (PNF) (n=9) or passive stretching (PASS) (n=9). Both modes of flexibility conditioning are popular within contemporary exercise and clinical settings and have demonstrated efficacy in improving range of motion. The contralateral limb and a prior ‘no exercise’ condition were used as controls. The PNF and PASS modes of conditioning improved passive hip flexibility to a similar extent (mean 19.3% vs. baseline, intervention limb, p<0.01) but did not alter knee flexor strength (overall mean 309.6±81 N) or sensorimotor performance (force and positional errors: 2.3±8.2% and 0.48±7.1%). Voluntary and magnetically evoked electromechanical delays (EMD_V and EMD_E, respectively) were increased but to a greater extent following PASS compared to PNF (PASS: 10.8% and 16.9% lengthening of EMD_V and EMD_E, respectively vs. PNF: 3.2% and 6.2%, p<0.01).The attenuated change to electromechanical delay (EMD) performance during PNF conditioning suggests a preserved capability for rapid muscle activation, which is important in the maintenance of dynamic joint stability. That PNF was also equally efficacious in flexibility conditioning would suggest that this mode of flexibility training should be used over passive to help preserve dynamic joint stability capabilities at this extended and vulnerable joint position.     

终点裁判员判定名次方法的研究

径赛长距离跑非常引人注目,由于运动员参加人数多,运动水平各异,加上裁判员工作环境喧闹,其名次判定也容易出错,是裁判工作中的一个重点和难点。文章对终点裁判的记圈方法和判定名次进行了研究,结论认为:在大型比赛中,新终点磁性电子记圈牌更能得到观众、运动员、裁判员对比赛结果的公认,对裁判工作的名次判定和工作质量、效率是极大的提高,使终点裁判工作有条不紊,迅速准确。     

流体力学多功能实验仪的研制

研制了小型流体力学高水头多功能实验仪，实现了水力学及流体力学教学实验设备小型化，同时，又能达到大型设备的实验效果。该设备可进行文透里实验，粗、细不同管径的沿程阻力实验和局部阻力实验。实验仪除具有自循环、水头稳定、多功能、小型化、可移动及操作方便等优点外，其最大特点是水头显著提高，有效拓宽了雷诺数的实验范围，实现了现有小型设备所无法达到的实验效果。     

Influence of Magnetic Field on the Rectification Process of Binary Heterogeneous Azeotrope

To improve separate effect of binary heterogeneous azeotrope in the magnetic field with different magnetic induction intensity, the influence of magnetic field on the rectification process of binary heterogeneous azeotrope was investigated with l-butanol-water system. The results show that the composition of liquid-liquid phase equilibrium of l-butanol-water system has definitely changed, the composition of l-butanol in light phase （l-butanol layer） increases by 1. 17%-1.63% and the composition of water in heavy phase （water layer） increases by 1.21%-1.58% under the influence of magnetic field. By separation of magnetization, the composition of l-butanol increases by 0.8%-1.2% and the recovery ratio of 1 -butanol increases by 1.6%-2.5%. Magnetic field has positive effect, however, the magnetized effect is not in proportion to magnetic induction intensity and has an optimum condition, in the range of 0.25 T-0. 3 T.     

磁性SO2-4/ZrO2固体超强酸的制备及催化性能的研究

利用磁性对固体超强酸组装,制备出磁性SO42-/ZrO2固体超强酸催化剂,应用于合成乙酸异戊酯的反应中,最佳反应条件为:乙酸0.2mol,异戊醇0.4mol,磁性催化剂1.2 g,反应时间2.0h,酯化率可达93.7％.利用催化剂的磁性可将催化剂迅速分离,回收率达84.3％,并能重复使用.     

若干因素对铬天青-S显色的影响

研究了室温、缓冲液两种pH值、显色时间、显色剂量对食品中铝测定的铬天青-S显色的影响;铝含量和吸光度之间的线性关系.结果显示：室温从21℃升高到33℃,吸光度相应增加;pH5.7缓冲液较pH5.5的吸光度轻微增加;加入铬天青-S20分钟后至45分钟内显色稳定;将显色剂量减半后吸光度稍微降低,显色效果改善;铝含量在0.5-6μg/ml范围内与吸光度之间线性关系良好;铝含量增至8μg/ml时失去线性关系;方法的重复性较好.     

低纯度Gd制成的Gd5Si1.8Ge2.2的磁热效应

实验中使用国产2N级金属Gd粉为原料，用电弧熔炼法在氩气气氛中制备了Gd5Si1.8Ge22合金，并通过X射线衍射仪和超导量子磁强计分析手段对合金的性能进行测试和分析．发现合金没有重现一级磁相变和巨磁热效应，这是由于国产2N级Gd中杂质等因素时磁相变、磁热性能产生了重要影响，导致一级磁相变的破坏及磁热效应的大幅度下降．     

帕金森病大鼠模型的骨髓间充质干细胞移植疗效的磁共振波谱探讨

目的利用1.5T质子磁共振波谱（^1H-MRS）监测活体帕金森病大鼠模型骨髓间充质干细胞（mesenchymal stem cells,MSCs）移植治疗前后纹状体区的神经代谢变化,以探讨1．5T磁共振波谱分析在评价MSCs移植术疗效中的应用价值。方法30只正常大鼠,以6-羟基多巴胺（6-OHDA）单侧（右侧）损毁制备偏侧帕金森病模型。在活体状态下,分别于造模后3周、MSEs移植后4周及8周应用Philips1．5T临床型磁共振仪扫描,对双侧纹状体区进行^1H—MRS采集,分析该区N-乙酰天门冬氨酸／肌酸（NAA／Cr）、胆碱／肌酸（Cho／Cr）比值变化,同时对大鼠进行行为学检测。利用黑质酪氨酸羟化酶免疫组织化学染色对黑质致密部（SNc）神经元进行定量分析。结果MSCs移植后8周组（C组）大鼠损毁侧（右侧）NAA／Cr比值与未处理组（A组）和MSCs移植后4周组（B组）相比明显升高（P〈0．05）;B,C组损毁侧Cho／Cr比值较A组明显降低（P〈0．05）,且分别明显低于其对侧（P均〈0．05）。B,C组旋转圈数分别较A组低（P均〈0．05）正组旋转圈数较B组显著降低（p〈0．05）。三组损毁侧SNCTH阳性细胞生存率无显著差异（P均〉0．05）。结论1．5T磁共振波谱可以作为一种活体无创性检测方法,对帕金森病大鼠模型纹状体区MSCs细胞移植疗效进行动态监测而作出有价值的评价。     

乙二胺四乙酸桥联锰配合物的结构和磁行为

A trinuclear Mn(Ⅱ)coordination complex Mn_3(HEDTA)_2·10H_2O(EDTA=ethylene diamine tetraacetic acid)1 has been synthesized and characterized by X-ray crystal structure determination.In addition,IR spectrum,thermogravimetric analysis,electron paramagnetic resonance(EPR)spectra and magnetic susceptibility of this complex are discussed.X-ray determination indicates that six-and seven-coordinate modes between Mn(Ⅱ)and H_4EDTA exist alternately in 1.Furthermore, detailed discussion of magnetic ordering in the temperature range of 2～300 K reveals the antiferromagnetic interactions in the complex.     

ZnO基稀磁半导体材料的研究进展

稀磁半导体（DMS）材料同时利用了电子的电荷和自旋属性,具有优异的磁、磁光、磁电等性能,在材料科学和未来自旋电子器件领域具有广阔的应用前景.ZnO基稀磁半导体材料的研究主要集中在：（1）优化生长参数,获得高质量的薄膜;（2）选择不同的掺杂元素与掺杂量,通过单掺杂或共掺杂技术,提高材料的居里温度,奠定其应用的基础.