共查询到20条相似文献,搜索用时 31 毫秒
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Lingyun Zhou Minghe Zhang Yunchang Fu Jiaxian Wang Xingyi Li 《Chinese Journal of Lasers》1993,2(2):189-191
We treated the callus of high-quality Yunan rice DR453 by He-Ne laser, then found the seedling of these callus emerging to an earlier date and the green seedlings differentiation rate is much higher than that of the callus not treated with laser (CK). It is useful to research the breeding on the tissue culture. 相似文献
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Suspension culture is an essential large-scale cell culture technique for biopharmaceutical development and regenerative medicine. To transition from monolayer culture on the culture surface of a flask to suspension culture in a bioreactor, a pre-specified cell number must first be reached. During this period of preparation for suspension culture, static suspension culture in a flask is generally performed because the medium volume is not large enough to use a paddle to circulate the medium. However, drawbacks to this static method include cell sedimentation, leading to high cell density near the bottom and resulting in oxygen and nutrient deficiencies. Here, we propose a suspension culture method with acoustic streaming induced by ultrasonic waves in a T-flask to create a more homogeneous distribution of oxygen, nutrients, and waste products during the preparation period preceding large-scale suspension culture in a bioreactor. To demonstrate the performance of the ultrasonic method, Chinese hamster ovary cells were cultured for 72 h. Results showed that, on average, the cell proliferation was improved by 40% compared with the static method. Thus, the culture time required to achieve a 1000-fold increase could be reduced by 32 h (a 14% reduction) compared with the static method. Furthermore, the ultrasonic irradiation did not compromise the metabolic activity of the cells cultured using the ultrasonic method. These results demonstrate the effectiveness of the ultrasonic method for accelerating the transition to large-scale suspension culture. 相似文献
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设计了触发间隔从100 ms到5 ms可调的双脉冲触发器驱动TEA CO2激光器高压开关,用以模拟激光器不同的输出脉冲重复频率。用该装置精确控制的不同激光脉冲重复频率下,对抛物面型光船模型进行了大气模式激光推进中冲量耦合系数的实验研究。发现冲量耦合系数随着重复频率的增加而下降,而单位时间内光船获得的冲量耦合系数的增量则随着重复频率的增加而增大。初步分析认为,这是由于飞行器内的空气未得到充分的补充造成的。 相似文献
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激光血管外照射治疗可行性研究 总被引:2,自引:0,他引:2
为探讨激光血管外照射治疗的可行性,测试了人活体血管外照射以及模拟血管内照射的光能流率分布情况。研究表明,激光血管内、外照射的总光能流率的平均值分别为10.81W/cm2与1.11W/cm2,两者相差一个数量级。为获得血管内照射相应的光能流率,建议采用20mW632.8nmHe-Ne激光;垂直入射于人皮肤外表:尽可能选择血管暴露的病人或较为暴露的血管;选择被照射血管直径为6mm左右。本实验结果,特别是在人活体血管内探测到的实验数据,将有益于光在人体组织内传播特性的研究。 相似文献
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Yasutaka Hanada Koji Sugioka Takayoshi Tsuchimoto Iwao Miyamoto Katsumi Midorikawa 《Applied Surface Science》2009,255(24):9885-9888
A microchip made of UV transparent polymer (CYTOP) that can perform selective cell culture has been fabricated by F2 laser surface modification. The refractive index of CYTOP is almost the same as that of culture medium, which is essential for three-dimensional (3D) observation of cells. The F2 laser modification of CYTOP achieves hydrophilicity only on the laser irradiated area with little deterioration of the optical properties and surface smoothness. After the laser modification, HeLa cells were successfully cultured and strongly adhered only on the modified area of CYTOP. The cells patterned on CYTOP were applied for clear 3D observation using an optical microscope in phase contrast mode. 相似文献
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Chie Hosokawa Yasutaka Sakamoto Suguru N. Kudoh Yoichiroh Hosokawa Takahisa Taguchi 《Applied Physics A: Materials Science & Processing》2013,110(3):607-612
We demonstrated the stimulation of neurons at a single-cell level in cultured neuronal network by a focused femtosecond laser. When the femtosecond laser was focused on a neuron loaded with a fluorescent calcium indicator, the fluorescence intensity immediately increased at the laser spot, suggesting that intracellular Ca2+ increases in the neuronal cell due to the femtosecond laser irradiation. The probability of Ca2+ elevation at the laser spot depended on the average laser power, irradiation time, and position of the focal point along the optical axis, indicating that the femtosecond laser activates neurons because of multiphoton absorption. Moreover, after laser irradiation of a single neuron cultured on multielectrode arrays, the evoked electrical activity of the neurons was demonstrated by electrophysiological systems, which concluded that the focused femtosecond laser could achieve stimulating a single neuron in a neuronal network with high spatial and temporal resolution. 相似文献
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《Current Applied Physics》2014,14(4):614-620
A high repetition rate (500 kHz) solid state laser was used for the ablation process in a Pulsed Laser Deposition (PLD)/Vapor–Liquid–Solid (VLS) growing. A ZnO target was ablated with laser powers between 0.6 W and 1.2 W, and a variable number of pulses per train and trains frequencies. ZnO structures were grown on gold patterned and unpatterned substrates surfaces. Enhanced growth of the nanostructures could be noticed on the catalyst patterned surfaces. Better nanowire morphologies were also observed for bigger number of laser pulses per train. The enhancements are more evident for low laser powers. Based on plume expansion investigations, by using a high speed camera and a Particle-In-Cell (PIC) Monte-Carlo based simulations, the nanostructure morphology variations could be understood on the basis of the plume particles diffusion process and thin film versus VLS growing competition. 相似文献
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Generation of high-energy dual-wavelength domain wall pulse with low repetition rate in an HNLF-based fiber ring laser 下载免费PDF全文
The generation of high-energy dual-wavelength domain wall pulse with a low repetition rate is demonstrated in a highly nonlinear fiber (HNLF)-based fiber ring laser. By introducing the intracavity birefringence-induced spectral filtering effect, the dual-wavelength lasing operation can be achieved. In order to enhance the cross coupling effect between the two lasing beams for domain wall pulse formation, a 215-m HNLF is incorporated into the laser cavity. Experimentally, it is found that the dual-wavelength domain wall pulse with a repetition rate of 77.67 kHz could be efficiently obtained through simply rotating the polarization controller (PC). At a maximum pump power of 322 mW, the 655-nJ single pulse energy in cavity is obtained. The proposed configuration provides a simpler and more efficient way to generate high energy pulse with a low repetition rate. 相似文献
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This paper presents the results of experimental study on the effect of electric field on the ablation rate during the nanosecond pulsed laser ablation of aluminum and copper in deionized water. The effect of electric field strength on the material removal rate and its mechanisms were investigated both in the electric field parallel and perpendicular to the laser beam path schemes. The ablation rate was estimated by measuring the dimensions of craters on the target induced by laser. The crater dimensions and optical properties of the produced colloidal nanoparticles were characterized by means of optical microscopy and UV–Vis absorption spectroscopy, respectively. The results indicate that pulsed laser ablation in the presence of an electric field significantly leads to higher material removal rate. The experimental results also confirm that the crater geometry extremely depends on the direction of the electric field with respect to the laser beam direction. The UV–Vis spectra show that the nanoparticles production efficiency increases with increasing the electric field strength. 相似文献
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On the basis of analysis and principles of the operational modes and mode sweep of a ring laser, a microcomputer system for automatic mode sweep of ring laser angular rate sensor is presented. A 0~300 V continuous adjusted power supply system for PZT used to accurately adjust the cavity lens of the ring laser also is described in the paper. The test result shows that the microcomputer system could solve the problem of automatic mode sweep of ring laser successfully. 相似文献
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YANG Heng Frank Bosselman CHEN Ming 《Chinese Journal of Lasers》1999,8(2):137-141
1IntroductionTheRingLaserAngularRateSensor(RingLaserGyroRLG)wasdefinedasatypeofactiveresonatorgyro.HerconceivedtheRLGin1961[1... 相似文献
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低He气压下Rb(5P3/2)激发态有效辐射率的计算与测量 总被引:1,自引:1,他引:0
计算和测量了Rb-He混合蒸气中Rb(5P3/2)共振能级的有效辐射率,使用单模半导体激光器(泵浦激光)将Rb原子激发至5P3/2态,另一调谐到5P3/2→7S1/2的单模激光束(检测激光)与泵浦束反平行通过样品池,并在池的直径方向平行移动,通过对检测激光束的吸收测定了激发态原子密度及其空间分布.由于辐射陷获存在,有效辐射率是自然辐射率与透射因子(发射的光子在探测区域内没有被吸收的平均概率,它与吸收截面及激发态原子密度和空间分布有关)的乘积.5P3/2原子密度及其空间分布结合5P3/2←5S1/2跃迁线的碰撞增宽计算了透射因子,从而得到了不同He气压下,Rb D2线的有效辐射率.从5P3/2→5S1/2跃迁线强度I780的测量,得到的不同He气压下有效辐射率的比值与理论计算得到的比值相符. 相似文献
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为了提高反鱼雷鱼雷(ATT)激光近炸引信对来袭鱼雷的捕获率,首先根据鱼雷目标的激光反射特性,分析了鱼雷目标回波功率随激光束入射角度和入射位置的变化规律。采用空间解析几何方法描述了ATT与来袭鱼雷的交会模型,给出了任意交会距离和姿态时目标回波功率计算方法。根据系统最小探测功率,建立了水中单光束扫描激光引信捕获率蒙特卡罗仿真模型,仿真了系统捕获率随激光脉冲频率的变化关系,获得了探测不同距离目标的最大捕获率和相应的激光扫描频率和脉冲频率。结果表明:当激光扫描频率为15 Hz,脉冲频率为4 kHz,系统能可靠捕获距离9 m内目标。所得系统捕获率仿真模型和结果可为ATT单光束扫描激光引信系统设计提供理论参考。 相似文献
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研究了强激光辐照碳/碳复合材料靶材引起的烧蚀现象及蒸气压对烧蚀速率的影响。基于傅里叶定律,建立了强激光辐照靶材的热传导模型,模拟了忽略蒸气压影响时烧蚀速率随功率的变化;通过Mott-smith近似方法描述了Knudsen层间断区域,分析了间断两侧表面粒子状态参数;结合质量连续方程和蒸气压与温度关系方程,并由气体状态方程描述蒸气流状态,对蒸气压条件下激光烧蚀碳/碳复合材料靶材的速率随功率变化的关系进行了数值模拟。结果表明,在高能激光对靶材的烧蚀过程中,蒸气压力变化会导致靶材的饱和蒸气温度发生变化,进而影响烧蚀速率且使其随功率呈非线性变化,与忽略蒸气压作用时的线性变化规律相差较大,从理论上解释了忽略蒸气压导致的实验数据与理论结果的差异。 相似文献