共查询到18条相似文献，搜索用时 250 毫秒
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对不同激光波长和不同浓度蔗糖溶液偏振光旋光度进行了测量,由旋光度与浓度关系拟合计算出了蔗糖溶液在不同激光波长下的旋光率,由蔗糖溶液旋光率与波长倒数平方关系和数据拟合分析,证实了蔗糖溶液旋光率与光波长倒数的平方成正比,得到了蔗糖溶液旋光率与波长相对应的函数关系,由此关系得到的蔗糖溶液589.3nm波长旋光率与标准自动旋光仪测量结果相符。 相似文献
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激光脉冲激发的超声脉冲波形的理论研究 总被引：1，自引：0，他引：1
在激光热弹产生超声的研究中，对于产生超声的激光脉冲波形，大都是采取简化处理了的矩形脉冲或三角形脉冲，这样的处理虽然在计算上较易得出结论，但它与真实的高斯激光脉冲有较大的差别。为此笔者采用更接受于实际激光脉冲波形的梯形脉冲模型，应用热传导方程和Navier-stokes方程对半无限大介质中所激发的超声脉冲特性进行了计算研究，结果得出了比矩形脉冲更具有普遍性的结果，也与实验结果相符。 相似文献
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本文提供了一种带自适应拼接的移相采样技术,利用FPGA技术在各种环境下都可以稳定可靠的利用较低的工作频率下完成高速脉冲采样,可以广泛应用于脉冲信号的脉宽、到达时间等特性参数的测量. 相似文献
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本文以临床广泛使用的气管插管作为研究对象,对其表面振动进行了实验测量,搭建了导波菌膜抑制实验系统,测量了导波振动幅度与插管菌膜抑制效果之间的关系。实验发现增加导波振动后的插管,其菌膜形成时间明显延长,菌膜抑制效果与导波振动幅度呈正比关系。较好的实验结果揭示了超声导波对于菌膜抑制的有效性,为临床抗菌,尤其是菌膜的抑制提供了一种新的物理方法。 相似文献
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This paper deals with the analytical and experimental investigations of an open-loop pulse-width-modulated d.c. motor speed control system. The analysis is carried out by two different approaches, circuit approach and the lattice function approach. From the circuit approach, the relationship between the current-ripple-factor and the pulse width is obtained. The lattice function approach yields the relationship between pulse width and the speed variation. There is good correlation between the experimental and theoretical results. 相似文献
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ＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＴＨＥＦＲＡＣＴＡＬＳＡＰＰＥＡＲＥＤＯＮＡＬＵＭＩＮＩＵＭＦＯＩＬＩＲＲＡＤＩＡＴＥＤＢＹＩＮＴＥＮＳＥＲＥＬＡＴＩＶＩＳＴＩＣＥＬＥＣＴＲＯＮＢＥＡＭ￥ＧａｏＨｕａｉ－ｌｉｎ；ＰａｎＹｕ－ｌｉ（ＣｈｉｎａＩｎｓｔ... 相似文献
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Using femtosecond laser to fabricate highly precise interior three-dimensional microstructures in polymeric flow chip 总被引：1，自引：0，他引：1
This paper reports using femtosecond laser marker to fabricate the three-dimensional interior microstructures in one closed flow channel of plastic substrate. Strip-like slots in the dimensions of 800 μm×400 μm×65 μm were ablated with pulse Ti:sapphire laser at 800 nm (pulse duration of ～120 fs with 1 kHz repetition rate) on acrylic slide. After ablation, defocused beams were used to finish the surface of microstructures. Having finally polished with sonication, the laser fabricated structures are highly precise with the arithmetic roughness of 1.5 and 4.5 nm. Fabricating such highly precise microstructures cannot be accomplished with nanosecond laser marking or other mechanical drilling methods. In addition, since laser ablation can directly engrave interior microstructures in one closed chip, glue smearing problems to damage molded microstructures possibly to occur during the chip sealing procedures can be avoided too. 相似文献
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This paper reviews our work on the application of ultrafast pulsed laser micro∕nanoprocessing for the three-dimensional (3D) biomimetic modification of materials surfaces. It is shown that the artificial surfaces obtained by femtosecond-laser processing of Si in reactive gas atmosphere exhibit roughness at both micro- and nanoscales that mimics the hierarchical morphology of natural surfaces. Along with the spatial control of the topology, defining surface chemistry provides materials exhibiting notable wetting characteristics which are potentially useful for open microfluidic applications. Depending on the functional coating deposited on the laser patterned 3D structures, we can achieve artificial surfaces that are (a) of extremely low surface energy, thus water-repellent and self-cleaned, and (b) responsive, i.e., showing the ability to change their surface energy in response to different external stimuli such as light, electric field, and pH. Moreover, the behavior of different kinds of cells cultured on laser engineered substrates of various wettabilities was investigated. Experiments showed that it is possible to preferentially tune cell adhesion and growth through choosing proper combinations of surface topography and chemistry. It is concluded that the laser textured 3D micro∕nano-Si surfaces with controllability of roughness ratio and surface chemistry can advantageously serve as a novel means to elucidate the 3D cell-scaffold interactions for tissue engineering applications. 相似文献
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In this paper, we study the variation of the thickness of patterned microchannel features in photoresist (PR) by two-step photolithography. The final PR thickness is determined by the thickness and width of the predefined PR pattern in the first-step lithography and the thickness of the spin-coated PR film in the second-step lithography. Thickness variation is demonstrated to be an important consideration within the critical pattern width that the capillary pressure is still dominant for forming the PR film thickness. With this mechanism of two-step photolithography, we demonstrate its ability to form multilevel channel features and its use to fabricate a cross-flow filter with two different pore sizes as a microfluidic application. 相似文献
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In this paper, we present a movement-based assay to observe adaptability in Caenorhabditis elegans locomotion behavior. The assay comprises a series of sinusoidal microchannels with a fixed wavelength and modulating (increasing or decreasing) amplitude. The channel width is comparable to the body diameter of the organism. Worms are allowed to enter the channel from the input port and migrate toward the output port. Within channel sections that closely match the worm's natural undulations, the worm movement is relatively quick and steady. As the channel amplitude increases or decreases along the device, the worm faces difficulty in generating the propulsive thrust, begins to slow down and eventually fails to move forward. A set of locomotion parameters (i.e., average forward velocity, number and duration of stops, range of contact angle, and cut-off region) is defined for worm locomotion in modulated sinusoidal channels and extracted from the recorded videos. The device is tested on wild-type C. elegans (N2) and two mutants (lev-8 and unc-38). We anticipate this passive, movement-based assay can be used to screen nematodes showing difference in locomotion phenotype. 相似文献