脉冲磁场对皮层神经元瞬时外向钾电流影响的初步实验研究

摘要：目的：随着现代工业的发展,磁场对人体的作用日趋广泛,越来越多的磁疗仪器的产生,并有着确实的疗效,但其机理并未明确,本文通过实验研究了脉冲磁场对小鼠皮层细胞的瞬时外向钾离子通道影响,以求能到得到更明确的机理的解释。方法：瞬时外向钾电流具有维持兴奋性细胞静息电位,决定细胞的兴奋性等重要作用,本试验采用频率为15Hz、强度为1.4mT的超低频脉冲磁场对小鼠的脑皮层神经细胞进行刺激,而后应用全细胞膜片钳技术测量并研究其瞬时外向钾电流特性。结果：实验发现超低频脉冲磁场对瞬时外向钾电流IA有一定的抑制作用,脉冲磁场作用可显著地影响通道的激活,对照组和脉冲磁场作用组通道半数激活电压分别为13.25±2.22mV和30.98±4.11mV（n＝6, P<0.05）,斜率因子分别为24.00±2.05mV和23.30±2.13mV（n=6,P<0.05）。结论：结果表明脉冲磁场作用皮层神经细胞可以改变其瞬时外向钾通道特性,从而影响动作电位的形成和发放频率,调节神经元的生理功能,有利于受损神经元的恢复和再生。     

脉冲磁场对神经元瞬时外向钾电流的影响

实验研究了脉冲磁场对小鼠皮层细胞的瞬时外向钾离子通道的影响.采用频率为15Hz、强度为1.4 mT的超低频脉冲磁场对小鼠的脑皮层神经细胞进行刺激,而后应用全细胞膜片钳技术测量其瞬时外向钾电流特性.实验发现,超低频脉冲磁场对瞬时外向钾电流IA有一定的抑制作用,脉冲磁场作用町显著地影响通道的激活,对照组和脉冲磁场作用组通道半数激活电压分别为(13.25±2.22)mV和(30.98士4.11)mV(n=6,P＜O.05),斜率因子分别为(24.00±2.05)mV和(23.30土2.13)mV(n=6,P＞0.05).结果表明,脉冲磁场作用皮层神经细胞町以改变其瞬时外向钾通道的特性,调节神经元的生理功能.     

全固态连续波555 nm黄-绿光激光器

报道了全固态连续波555 nm黄-绿光激光器,黄-绿激光分别由Nd:YAG和Nd:YVO₄晶体的946 nm和1342 nm谱线非线性和频产生,两条谱线各自晶体对应的能级跃迁分别为⁴F_3/2-⁴I_9/2和⁴F_3/2-⁴I13/2。实验中采用复合折叠腔结构,利用LBOI类临界位相匹配进行腔内和频,当注入到Nd∶YAG和Nd:YVO₄晶体的泵浦功率分别为12 W和8 W时,获得542 mW的TEM₀₀连续波555 nm黄-绿激光输出,4 h功率稳定度优于±3.7％。实验结果表明,采用Nd:YAG和Nd:YVO₄两种激光晶体进行腔内和频是获得黄-绿激光的高效方法,并可以应用到其它两种激光晶体进行腔内非线性和频,获得更多不同波长的激光输出。     

高平均功率腔内和频蓝光Nd:YAG激光器

高平均功率蓝光激光是当前固体激光技术研究热点之一。尽管通过Nd³⁺的⁴F_3/2→⁴I_9/2态谱线倍频可获得瓦级蓝光输出,然而其准三能级物理特性严重限制其更高功率输出。研究了Nd³⁺离子⁴F_3/2→⁴I_13/2态1.3 μm谱线腔内三倍频产生高平均功率蓝光激光,获得4.3 W蓝光激光输出,重复频率3.5 kHz,脉冲宽度150±10 ns,光束质量M²因子约为5±1。研究表明:Nd∶YAG晶体1.3 μm多谱线振荡是制约实验结果的重要因素,若克服多谱线振荡问题,有望获得10 W级蓝光激光输出。     

全固态589 nm复合腔连续波和频激光器

给出了一种复合腔结构和频激光器,用2台激光二极管阵列(LDA)经过光纤耦合分别单独端面抽运Nd:YVO₄和Nd:YAG晶体,其中Nd:YVO₄和Nd:YAG晶体所选择的能级跃迁分别为⁴F_3/2-⁴I_11/2和⁴F_3/2-⁴I_13/2,其对应激光跃迁波长分别为1 064 nm和1 319 nm,两基频激光束分别在两个子谐振腔中振荡,在其交叠区利用KTP II类临界相位匹配(CPM)进行腔内和频,获得了589 nm的和频激光。当抽运功率为8 W/14 W时获得了340 mW连续波TEM₀₀黄激光输出。光束质量因子M²<1.2,激光输出功率噪声低,4 h功率不稳定度小于±3％。该复合腔结构是实现LDA泵浦589 nm全固态黄光激光器一种有效的和频方法。     

在A3钢基材上激光熔覆G112合金的组织与性能

应用激光束将镍基合金粉末,熔覆在A₃钢表面上,可以显著改善其抗磨损性能。本文重点论述了该合金激光熔覆层、结合区、基材热影响区的组织结构及其相应的性能。获得结果。(1)G112合金激光熔覆层的显微结构主要为γ-Ni、Ni₃B,CrB、M₁₃(CB)₆的亚共晶结构,其硬度HV_0.1542～649。(2)覆层与基材间的结合带是含有Fe、Ni、Cr等元素的相互扩散带。(3)热影响区的组织主要为先共析铁素体、魏氏组织和少量的索氏体。(4)G112合金激光熔覆层具有优异的抗磨损性能,其相对耐磨性是A₃钢的6—7倍。其磨损机制为粘着磨损、磨粒磨损,疲劳磨损的复合磨损。     

光学膜吸收率与散射率测量台

西德LEYBOLD-HERAEUS高真空技术公司研究与生产一种名叫“LAMABS”的激光测量台,用于测定光学膜层的吸收与散射,其测量精度已达到吸收率A=士0.01％,散射率S=±1×10~(-5)。测量台的测量原理如下: ①吸收测量原理: 被测量样品用足够功率的氩离子激光器(输出功率约为1瓦)照射后,对由于吸收而产生的温升进行测量,就可直接测得介质反射镜的吸收。温升可用电阻温度计     

SF6饱和吸收稳频CO2激光器

利用SF₆吸收室对CO₂激光进行了饱和吸收引起的反拉姆凹陷的研究,把所获得的反拉姆凹陷对CO₂激光器的P(18)支线进行稳频,得到的频率稳定度为2×10^-10(伺服系统带宽为25赫芝时).提出了改进的途径并讨论了饱和吸收稳频激光器应用于外差激光雷达上的优点.     

高反射平面反射率的测量

本文研究一种籍助于激光光束对平面高反射介质镜面涂层的反射率进行测量的补偿方法。利用两个耦合的谐振腔,可以测定直径为激光光束那么大小区域的反射率,其精度约为±3×10~(-5)。这种方法也可用来测定单一镜面反射率的相对分布。这时,精度等于该方法的灵敏度±2×10~(-5)。     

离子色谱法同时测定梨子和梨树叶中的氯和硫

提出了梨子和梨树叶的消解方法。采用离子色谱电导检测法同时测定梨子和梨树叶中的氯和硫 ,方法检出限梨子和梨树叶中的Cl分别为 0 .3× 10 -6,6× 10 -6,梨子和梨树叶中的S分别为 0 .9× 10 -6,18× 10 -6;回收率为92 .0～ 10 2 .0 % ,RSD(n =10 ) 1.4 2～ 9.93%。     

Reflectance confocal‐laser‐scanning microscopy in vivo assessments of cigarette‐induced dynamic alterations of cutaneous microcirculation on histomorphological level

Objective: Until now, high resolution reflectance confocal‐laser‐scanning microscopy (CLSM) was used for observation of cutaneous morphology in vivo and in real time. We hypothesized that CLSM also allows observation of dynamic processes of cutaneous microcirculation. Methods: Reflectance CLSM (Vivascope1500; Lucid, Rochester, NY) was performed in 24 young male habitual smokers (23 years, range: 19–26, body mass index 23.9 ± 4.04) with relatively limited cigarette exposure (mean: 3.1 ± 2.4 pack‐years). Eight matched nonsmokers served as controls. The quantitative blood cell flow and the diameter of capillary loops were determined prior (baseline), during, as well as 5 and 10 min after smoking. Results: Baseline value for blood cell flow was 55.50 ± 2.33 cells/min, and decreased over 45% during smoking (30.43 ± 3.76/min; P = 0.02). They were still 22% lower (43.33 ± 2.45/min; P = 0.01) 5 min after smoking and exceeded baseline values 10 min after smoking by 13% (63.00 ± 3.10/min; P > 0.05). The baseline values for capillary loop diameter (9.03 ± 0.22 μm) decreased by 21% (7.18 ± 0.28 μm; P = 0.03) during smoking, remained about 9% (8.23 ± 0.18 μm; P = 0.01) lower 5 min after smoking and exceeded baseline values insignificantly by 4% (9.38 ± 0.28 μm; P > 0.05) 10 min after smoking. There were no significant differences to the controls. Conclusion: Reflectance CLSM enables qualitative and quantitative observation of dynamic processes of cutaneous microcirculation on histomorphological level. Microsc. Res. Tech., 2009. © 2008 Wiley‐Liss, Inc.     

高功率CO_2激光对远场HgCdTe探测器的干扰实验

理论分析和实验研究了高功率CO2激光对远场光导型长波红外HgCdTe探测器的干扰损伤。采用激光辐照探测器的温升理论模型,根据实验参数,讨论了高功率激光对长波红外探测器的损伤机理,计算了温升与辐照时间和功率的关系,并和CO2激光器在距离15km处辐照光导型长波红外HgCdTe探测器的实验结果进行对比分析。实验结果表明,2.5kW连续CO2激光经过大气衰减后在15km处激光功率密度可达0.161W/cm2,计算可知此时会聚到探测器靶面处的功率密度为140W/cm2;靶面处功率密度为20.5W/cm2时,对探测器产生干扰;靶面处功率密度为110W/cm2时,达到损伤,计算此时探测器表面温度已达到Hg析出温度,这一实验现象和理论计算预期结果相吻合。实验结论对研究探测器的激光防护和激光干扰星载探测器技术具有指导意义。     

A precision high-voltage source

A compact multipurpose regulated stabilized high-voltage (from 0 to ± 10 kV) power source for use in industrial and scientific equipment (mass spectrometers, ion optics, photomultiplier tubes, etc.) has been developed. The maximum load current is 400 μA, the noise and ripple in the output voltage are 50 mV or less, and the drift is no more than 2 × 10^?4 °C^?1. The source is the 95 × 60 × 30 mm module.     

Effects of ultramorphological changes on adhesion to lased dentin-Scanning electron microscopy and transmission electron microscopy analysis

Dentin irradiation with erbium lasers has been reported to alter the composite resin bond to this treated surface. There is still a lack of studies reporting the effect of erbium lasers on dentin organic content and elucidating how laser treatment could interfere in the quality of the resin-dentin interface. This study aimed to evaluate the effect of erbium laser irradiation on dentin morphology and microtensile bond strength (μTBS) of an adhesive to dentin. Seventy-two dentin disks were divided into nine groups (n = 8): G1-Control (600-grit SiC paper); Er:YAG groups: G2- 250 mJ/4 Hz; G3- 200 mJ/4 Hz; G4- 180 mJ/10 Hz; G5- 160 mJ/10 Hz; Er,Cr:YSGG groups: G6- 2 W/20 Hz; G7- 2.5 W/20 Hz; G8- 3 W/20 Hz; G9- 4 W/20 Hz. Specimens were processed for cross-sectional analysis by scanning electron microscopy (SEM) (n = 3), transmission electron microscopy (TEM) (n = 2), and adhesive interface (n = 3). Forty-five dentin samples (n = 5) were restored and submitted to μTBS testing. ANOVA (α = 5%) revealed that G1 presented the highest μTBS values and irradiated groups did not differ from each other. TEM micrographs showed a superficial layer of denatured collagen fibrils. For SEM micrographs, it was possible to verify the laser effects extending to dentin subsurface presenting a rough aspect. Cross-sectional dentin micrographs of this hybridized surface revealed a pattern of modified tags with ringlike structures around it. This in vitro study showed that erbium laser irradiation interacts with the dental hard tissue resulting in a specific morphological pattern of dentin and collagen fibrils that negatively affected the bond strength to composite resin.     

红外D2喇曼激光器的实验研究

用高功率TEA CO₂激光TEM₀₀模泵浦低温多程池中的D₂,利用其受激转动Raman散射(SRRS),我们获得了11～14μm光谱范围内可调谐Raman激光输出。典型的TEA CO₂ 10R(20)线30MW输入泵浦可获得大约7.93MW的12.5μm红外激光输出。     

Ultrastructural analysis of radicular dentine surface submitted to CO2 laser at different parameters

Background: There are no reported studies comparing different parameter settings of the CO₂ laser and irradiation direction considering their effect on the morphology of radicular dentine surface. Purpose: To evaluate the alterations of radicular dentine (cervical, middle, and apical thirds) irradiated with CO₂ laser at different potencies and irradiation directions. Study Design: Roots of 35 canines were prepared and randomly distributed according to the laser potency: GI: no laser treatment (control) (n = 5); GII, 2 W (n = 10); GIII: 4 W (n = 10); GIV: 6 W (n = 10). Each group (excepting GI) was divided in two subgroups according to the irradiation distance (n = 5): (A) parallel and (B) perpendicular to the root canal walls. The roots were splited longitudinally and analyzed by scanning electron microscopy in a qualiquatitative way. The scores were submitted to Kruskal–Wallis and Dunn's tests. Results: No significant statistical differences were observed among root canal thirds (P > 0.05). The specimens irradiated with 2 W were statistically different (P < 0.05) from those irradiated with 4 and 6 W, which were statistically similar between themselves (P > 0.05). With 2, 4, and 6 W at in parallel irradiation and 2 W in perpendicular direction, the surface showed a fissured aspect. With 4 W in perpendicular direction and 6 W in parallel and perpendicular direction, surface was modified by laser action and exhibited fused areas. Conclusions: The intensity of the effects is dependent on the laser‐irradiation dosimetries. Alterations were more intense when higher parameters were used. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.