前列腺低温微创治疗及器件的研究

利用低温冷冻破坏前列腺增生或肿瘤组织治疗疾病具有许多的优点,如出血少、痛苦小,有时甚至不需要麻醉。前列腺冷冻术可采用两种方法,即穿刺式和接触式。穿刺式就是将探针直接插入病灶组织中心,予以冷冻,主要用于较小的病灶;接触式就是将探针冷冻区接触病灶组织表面予以冷冻,主要用于较小的前列腺增生或不规则的肿瘤等,有时也可将二者结合使用。冷冻术最大的优点还在于可防止肿瘤细胞的扩散。文中详细介绍前列腺冷冻治疗的机理、冷冻探针的结构特点及临床应用效果。     

VM1000型热真空试验设备的研制

热真空试验设备主要为航天产品组件提供高真空、冷热环境及冷黑背景,模拟航天器及其组件在轨各种模式下的工作性能指标是否满足设计要求。热真空设备主要模拟空间两个参数,即高真空环境和冷热环境。文中介绍了VM1000型热真空试验设备的参数设计指标、设备组成及设备研制过程,并对设备的真空、温度等相关性能参数进行测试,验证设计参数是否满足要求。     

阿列尼乌斯模型在红外微型金属杜瓦的真空寿命试验研究中的应用

红外微型金属杜瓦是红外探测器中必不可少的一种电真空组件.本篇介绍了它的结构特点,并探讨运用阿列尼乌斯模型进行加速寿命试验的方法,来估计红外微型金属杜瓦常温状态下的真空寿命.     

一种热真空试验设备的研制

热真空试验设备主要为航天产品组件提供高真空、冷热环境,模拟星载器件在轨各种模式下的工作性能指标是否满足设计要求。热真空设备主要模拟空间两个参数,即高真空环境和冷热环境。文中介绍了一种热真空试验设备的参数设计、设备组成及设备研制过程,并对设备的进行真空、温度等相关性能参数的测试,验证设计参数是否满足要求。     

非临界压缩光场探测的实验方案研究

压缩态光场作为一种重要的量子光源,在量子计算、量子通信、精密测量等领域有广泛的应用前景.在非临界压缩光场产生的理论预测中,阈值以上泵浦的简并光学参量振荡器(DOPO)产生横向空间分布为一阶厄米高斯模式的非临界压缩光场,具有对泵浦光功率波动鲁棒性的量子特性,因此在实验中具有重要的应用价值.然而该非临界压缩光场的横向幅角随机旋转,导致无法利用本底探针光对其压缩特性进行稳定的平衡零拍实验探测.本文提出利用DOPO同时产生的与压缩光场空间正交的明亮光场作为本底探针光的实验探测方案.理论分析表明,该方案虽然引入了真空噪声,但可以很好地抵消压缩光场空间模式随机旋转引入的探测输出动态波动,得到3 d B的稳定探测结果,且对本底探针光的相位波动具有鲁棒性.因此该探测方案对于非临界压缩光场的实验研究具有重要的实用价值.     

外科冷冻探针周围组织温度场的焓法求解

本文通过用焓模型求解非线性生物传热方程,研究了低温外科中冷冻探针周围组织的瞬态温度场,使生物组织的“冷冻损伤”形状、成长速率及最终稳态冷冻区域大小得以确定.本文旨在一方面为低温外科提供必要的理论依据,另一方面使一般相变导热问题的焓法求解得以进一步深入及推广.     

双冷针冷冻手术中冻结相变传热的数值模拟

建立了生物组织(含正常组织与肿瘤)冻结过程相变传热的数学模型.模型中采用树状分形方法模拟血管的结构形态,同时考虑了组织在冻结过程中存在冻结区、糊状区和未冻结区三个区域.对生物组织在同时插入两根探针时冻结过程中温度场分布及冰晶生长规律进行了模拟.模拟结果表明:在冷冻初期,冰晶的生长速度较快,到了后期冰晶生长速度明显减慢;探针间距在冷冻初期对冰晶生长产生较大影响,随着冷冻时间的增加这种差别会逐渐减少.     

二维非正交坐标斜方格金属光子带隙结构

金属光子带隙结构在高能加速器、微波真空电子器件和太赫兹波源等方面具有重要的应用前景.基于实空间传输矩阵理论，详细研究了非正交坐标系下二维斜方格金属光子带隙结构，给出了计算横电模、横磁模完全带隙结构的一般公式，并分析了填充系数、任意斜角及金属柱横截面对带隙结构的影响.计算结果在退化为正方格情况下时，与其他方法的计算结果取得很好的一致. 关键词： 光子晶体 金属光子带隙 传输矩阵法 微波真空电子器件     

用ZnS做诱导金属滤光片的间隔层

从制备工艺稳定性出发,设计的诱导金属滤光片的膜系结构与以往设计的膜系结构有所不同,即将n_L低折射率冰晶石间隔层改用n_H高折射率ZnS做间隔层。如果金属与间隔层结合良好,本文中给出的设计计算公式适合于做间隔层的任意膜层。通常膜系的透光率T是膜层厚度nd的函数T=f(nd)。高折射率n_H的膜层函数T_H=f(n_Hd)变化较快,低折射率n_L的膜层函数T_L=f(n_Ld)变化较慢,尤其是在膜层厚度接近λ_0/2的区域更为明显。实践证明选用高折射率ZnS做诱导金属银滤光片的间隔层比选用低折射率冰晶石做间隔层制备工艺稳定,产品合格率高。     

真空变温薄膜电阻测试仪器的设计与应用

设计了自制真空变温薄膜电阻测试仪器,可以实现粗真空条件下,从室温到300℃的四探针法薄膜电阻测试.该仪器适用于开展薄膜物性与电阻和温度相关的实验,例如,金属与半导体薄膜的温度-电阻特性实验,二氧化钒薄膜热滞效应实验等.     

Bridging biomolecules with nanoparticles: surface‐enhanced Raman scattering from colon carcinoma and normal tissue

In order to get insight into the chemical heterogeneities of solid tumors, here we report the first surface‐enhanced Raman scattering (SERS) experiment from normal and altered epithelial layer in human colon carcinoma tissues. The Ag colloidal nanoparticles that can be incorporated into the interstitial space in solid tumors or those penetrating into cytoplasm or nucleus of many cells allowed high quality SERS signal. Different tissue structures of tumor and normal colon have characteristic features in SERS spectra. Prominent SERS features of malignant tissue spectra are related to the strong enhancement of the bands preponderantly attributable to DNA or RNA bases. The preliminary studies demonstrate that it is possible to probe Ag colloidal nanoparticles adsorption onto the tissue resulting in a strong molecular signaling with high specificity and rapid acquisition time using visible laser line excitation. Copyright © 2008 John Wiley & Sons, Ltd.     

低温微创手术治疗探头周围组织温度分布研究

采用低温方法对人体深部肿瘤进行杀伤时,既要求对肿瘤组织有最大的杀伤效果,又要保证正常组织,特别是一些重要器官组织,能免受冷冻伤害。文中对冷冻治疗探头形成冰球的大小、以及冻结界面周围组织温度分布进行传热分析和测试,以给出安全区和危险区的范围,这可以为外科手术医生设计低温手术方案提供参考依据。     

基于探测超声的新型生物组织光声层析成像

利用一束单频探测超声穿过由脉冲激光照射产生的光声激发区域，使之与光致声场产生相互作用，光声信号将耦合到探测束上，再解调探测超声来重建光吸收区域的图像，可以得到丰富的组织信息.该信息不仅反映了组织中光吸收的特性，也反映了组织的声学特性.实验中，通过旋转超声探测器进行数据采集，并利用滤波反投影算法重建图像，可得到高信噪比的光声层析图像.由于激光的窄光谱线宽，其吸收是特征分子选择性的，所以此方法既是一种无损伤的结构层析成像方法，也可用于组织的功能成像.     

Characteristics of light scattering by normal and modified areas of skin tissue

Results from numerical calculations and experimental studies of the optical backscattering coefficients and changes in the polarization characteristics of normal and modified (birthmark, scar) skin tissue structures are presented. It is shown that determining the Mueller matrix is an effective way of detecting changes in the structure of skin tissue in vivo which reflects changes in the depolarization of light by an object for different polarization parameters of the incident (probe) radiation. The depolarization of light is found to be symmetric for normal areas of skin and antisymmetric for skin tissue with a modified structure. It is proposed that the polarization characteristics of scattered radiation be used in detecting damaged areas of skin tissue.     

Experiment Researches on Active Fibre Probe for Scanning Near-field Optical Microscopy

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Tissue velocity imaging of coronary artery by rotating-type intravascular ultrasound

Intravascular ultrasound (IVUS) provides not only the dimensions of coronary artery but the information of tissue components. In catheterization laboratory, soft and hard plaques are classified by visual inspection of echo intensity. So-called soft plaque contains lipid core or thrombus and it is believed to be more vulnerable than a hard plaque. However, it is not simple to analyze the echo signals quantitatively. When we look at a reflection signal, the intensity is affected by the distance of the object, the medium between transducer and objects and the fluctuation caused by rotation of IVUS probe. The time of flight is also affected by the sound speed of the medium and Doppler shift caused by tissue motion but usually those can be neglected. Thus, the analysis of RF signal in time domain can be more quantitative than intensity of RF signal. In the present study, a novel imaging technique called "intravascular tissue velocity imaging" was developed for searching a vulnerable plaque. Radio-frequency (RF) signal from a clinically used IVUS apparatus was digitized at 500 MSa/s and stored in a workstation. First, non-uniform rotation was corrected by maximizing the correlation coefficient of circumferential RF signal distribution in two consecutive frames. Then, the correlation and displacement were calculated by analyzing the radial difference of RF signal. Tissue velocity was determined by the displacement and the frame rate. The correlation image of normal and atherosclerotic coronary arteries clearly showed the internal and external borders of arterial wall. Soft plaque with low echo area in the intima showed high velocity while the calcified lesion showed the very low tissue velocity. This technique provides important information on tissue character of coronary artery.     

Quantitative Time-Resolved Fluorescence Spectrum of the Cortical Sarcoma and the Adjacent Normal Tissue

The difference in time-resolved fluorescence spectrum between the cortical sarcoma and the adjacent normal tissue was studied in both experimental and theoretical ways. The Clinical data were obtained in vivo using a time-resolved fluorescence spectrometer employing a single fiber-optic probe for excitation and detection. Tissue was modeled as s-180 sarcoma tumor surrounded with normal muscle and was mediated by the Palladium-porphyrin photosensitizer (Pd-TCPP). The emitted fluorescence was considered as arising from the tumor tissue or the normal muscle, due to the presence of the photosensitizer. A computational code which could simulating time-resolved fluorescence emission was presented and applied to comparing fluorescence decay of photosensitizer in different stages of tumor growth. In this code the different stages of the tumor was modeled through changing the time τ, the delay of the fluorescence photon emission and z _max, the thickness of the tumor. It was found in the in vivo experiment that the fluorescence from tumor tissue decayed more quickly than from the adjacent normal muscle. For the ten rats in the first experiment day, the mean decay constant of tumor T _s and normal tissue T _n were 554 and 526 μs, respectively. And T _s increased with the tumor growth, from 554 μs in the first day to 634 μs in the eighth day while T _s kept steady. It was believed that the more adequate oxygen supplied by the normal tissue can more effectively quench the fluorescence and in the normal tissue the photosensitizer lifetime is smaller. As a result the simulated time-resolved fluorescence spectrum of normal tissue showed more quickly decay. And the thickness of the tumor can also delay the fluorescence decay. Both the experimental and simulated results indicated that the germination of the tumor would increase the decay constant of the time-resolved fluorescence spectrum. So decay constant of the tumor tissue spectrum should be larger than that of adjacent normal tissue for the reason of hypoxia and overgrouth. This fact could be of use in the tumor diagnoses.     

Simulation of light delivery for photoacoustic breast imaging using the handheld probe

The photoacoustic tomography by using the handheld probe has a great potential in clinical breast imag- ing. However, tile shape of the probe limits the choice of light delivery in this setup. In this letter, we study two commonly used illumination types for handheld probe： bright-field illumination and dark-field illumination. Our results demonstrate several parameters have important impact on the photon fluence in deep breast tissue. The results will help to optimize the design of the photoaeoustie breast imaging system with a handheld probe.