光声光谱测试技术及在材料分析中的应用

光声光谱作为一种比较新型的材料无损测试技术，具有灵敏度高，能进行微量分析，以及不受样品形状限制等优点。本文对光声光谱测试技术的测试原理及测试系统组成进行了详细说明，并举例说明其在材料分析中的应用。     

光声光谱测试技术及在材料分析中的应用

光声光谱作为一种比较新型的材料无损测试技术，具有灵敏度高、能进行微量分析、以及不受样品形状限制等优点。本文对光声光谱测试技术的测试原理及测试系统组成进行了详细说明，并举例说明其在材料分析中的应用。     

层析技术的发展和应用——层析技术在生物制药中的应用

层析技术作为一项强大的纯化工具，广泛应用于多种行业。本文主要介绍了层析技术在生物制药生产中的应用情况，并对其工艺发展趋势进行了探讨。[编者按]     

线性调频技术在光声检测中的应用

利用线性调频对光强进行调制，是一种兼有脉冲和单频调制优点的一种新的激光强度调制技术。它的自相关函数更接近于δ函数，因此，它比 相关无声检测中常用的伪随机噪声编码调制，具有更宽的频谱，是一种进 行物质光学、热学和力学性质快速检测的良好方法。本文将简述该技术的 基本原理，实验装置及初步实验结果。本工作得到国家自然科学基金的资助。     

非线性频率电压变换器在光声检测中的应用

一、引言 光声效应是物质吸收了调制光能转变为声能的效应[1]。由于光声检测技术具有测量范围广,辐射波长宽,灵敏度高及试样要求低等优点,因此光声检测技术不仅可用于检测物质的弱吸收,而且可广泛用于进行物质的物理[2]、化学[3]及生物过程[4]的研究,以及物质特性的检测。采用非线性频率电压变换器制成的速度可调式斩光器,以其高度的稳定性,并配以锁定放大器,可以测量极其微弱的信号,在光产检测中有着广泛的应用前景。 二、工作原理 非线性频率电压变换器的线路图如图1所示。输入信号为一个连续方波信号,经过CC4069的整形后送往D触发器CC4…     

纳米胶体金免疫层析技术在农业领域的应用进展

胶体金标记免疫层析技术是一种新型的免疫学快速检测技术,具有敏感、特异、便捷、快速等特点。该技术已广泛应用于农产品残留的检测。文章介绍了该技术的基本原理,并概述了胶体金技术在农业领域的应用现状和发展前景。     

半导体光声层析中的电场效应

半导体光声层析中的电场效应方健文张淑仪（南京大学声学研究所近代声学国家重点实验室南京·２１００９３）１引言光声效应对样品的光学、热学性质差异非常敏感，利用光声效应对多层次固体样品进行无损的深度剖面检测一直是人们重视的课题。多年来已发展了多种获取固体深...     

光声显微镜技术的研究进展

光声显微镜技术具有新兴的一种非侵害性的显微成像技术,具有高分辨率、高对比度、穿透深度高的优点。简要介绍光声成像技术机理,总结报道了国内外几种典型的光声显微成像方法和光声显微图像重建算法的发展历程及其最新进展,指出该技术是一种很有应用前景的医学检测方法。     

应用光声技术测定薄型材料导温系数的研究

本文报导了用光声技术测试和研究薄型试样导温系数的结果,建立了该方法的理论模型,介绍了实验装置和数据处理的方法。用本装置对三种标准和亚标准试样的测试结果表明,实测值和文献推荐值相当吻合。本文的基本理论和实验方法同样也适用于其它有机、无机等薄型材料。     

Gold Nanoprisms as Optoacoustic Signal Nanoamplifiers for In Vivo Bioimaging of Gastrointestinal Cancers

Early detection of cancer greatly increases the chances of a simpler and more effective treatment. Traditional imaging techniques are often limited by shallow penetration, low sensitivity, low specificity, poor spatial resolution or the use of ionizing radiation. Hybrid modalities, like optoacoustic imaging, an emerging molecular imaging modality, contribute to improving most of these limitations. However, this imaging method is hindered by relatively low signal contrast. Here, gold nanoprisms (AuNPrs) are used as signal amplifiers in multispectral optoacoustic tomography (MSOT) to visualize gastrointestinal cancer. PEGylated AuNPrs are successfully internalized by HT‐29 gastrointestinal cancer cells in vitro. Moreover, the particles show good biocompatibility and exhibit a surface plasmon band centered at 830 nm, a suitable wavelength for optoacoustic imaging purposes. These findings extend well to an in vivo setting, in which mice are injected with PEGylated AuNPrs in order to visualize tumor angiogenesis in gastrointestinal cancer cells. Overall, both our in vitro and in vivo results show that PEGylated AuNPrs have the capacity to penetrate tumors and provide a high‐resolution signal amplifier for optoacoustic imaging. The combination of PEGylated AuNPrs and MSOT represents a significant advance for the in vivo imaging of cancers.     

X-ray computed tomography imaging of a tumor with high sensitivity using gold nanoparticles conjugated to a cancer-specific antibody via polyethylene glycol chains on their surface

Contrast agents are often used to enhance the contrast of X-ray computed tomography (CT) imaging of tumors to improve diagnostic accuracy. However, because the iodine-based contrast agents currently used in hospitals are of low molecular weight, the agent is rapidly excreted from the kidney or moves to extravascular tissues through the capillary vessels, depending on its concentration gradient. This leads to nonspecific enhancement of contrast images for tissues. Here, we created gold (Au) nanoparticles as a new contrast agent to specifically image tumors with CT using an enhanced permeability and retention (EPR) effect. Au has a higher X-ray absorption coefficient than does iodine. Au nanoparticles were supported with polyethylene glycol (PEG) chains on their surface to increase the blood retention and were conjugated with a cancer-specific antibody via terminal PEG chains. The developed Au nanoparticles were injected into tumor-bearing mice, and the distribution of Au was examined with CT imaging, transmission electron microscopy, and elemental analysis using inductively coupled plasma optical emission spectrometry. The results show that specific localization of the developed Au nanoparticles in the tumor is affected by a slight difference in particle size and enhanced by the conjugation of a specific antibody against the tumor.     

Contrast enhancement of computed tomography images by adaptive histogram equalization‐application for improved ischemic stroke detection

The visualization of computed tomography brain images is basically done by performing the window setting, which stretches an image from the Digital Imaging and Communications in Medicine format into the standard grayscale format. However, the standard window setting does not provide a good contrast to highlight the hypodense area for the detection of ischemic stroke. While the conventional histogram equalization and other proposed enhanced schemes insufficiently enhance the image contrast, they also may introduce unwanted artifacts on the so‐called “enhanced image.” In this article, a new adaptive method is proposed to excellently improve the image contrast without causing any unwanted defects. The method first decomposed an image into equal‐sized nonoverlapped sub‐blocks. After that, the distribution of the extreme levels in the histogram for a sub‐block is eliminated. The eliminated distribution pixels are then equally redistributed to the other grey levels with threshold limitation. Finally, the grey level reallocation function is defined. The bilinear interpolation is used to estimate the best value for each pixel in the images to remove the potential blocking effect. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 153–160, 2012     

纳米金在肿瘤诊断中的应用

纳米金具有独特的理化性能,在肿瘤诊断和治疗中取得了许多重要进展。综述了纳米金的结构组成、粒径尺寸、形貌特征对其本身性能的影响,介绍了纳米金对肿瘤标志物的检测和作为造影剂对肿瘤成像的研究进展,着重评述了纳米金应用于体内外肿瘤光学成像方面的研究情况,展望了其未来的发展前景。     

Detection of ultrawide-band ultrasound pulses in optoacoustic tomography

A laser optoacoustic imaging system (LOIS) uses time-resolved detection of laser-induced pressure profiles in tissue in order to reconstruct images of the tissue based on distribution of acoustic sources. Laser illumination with short pulses generates distribution of acoustic sources that accurately replicates the distribution of absorbed optical energy. The complex spatial profile of heterogeneous distribution of acoustic sources can be represented in the frequency domain by a wide spectrum of ultrasound ranging from tens of kilohertz to tens of megahertz. Therefore, LOIS requires a unique acoustic detector operating simultaneously within a wide range of ultrasonic frequencies. Physical principles of an array of ultrawide-band ultrasonic transducers used in LOIS designed for imaging tumors in the depth of tissue are described. The performance characteristics of the transducer array were modeled and compared with experiments performed in gel phantoms resembling optical and acoustic properties of human tissue with small tumors. The amplitude and the spectrum of laser-induced ultrasound pulses were measured in order to determine the transducer sensitivity and the level of thermal noises within the entire ultrasonic band of detection. Spatial resolution of optoacoustic images obtained with an array of piezoelectric transducers and its transient directivity pattern within the field of view are described. The detector design considerations essential for obtaining high-quality optoacoustic images are presented.     

A Gold Nanocage/Cluster Hybrid Structure for Whole‐Body Multispectral Optoacoustic Tomography Imaging,EGFR Inhibitor Delivery,and Photothermal Therapy

Gold nanocages (AuNCs) and gold nanoclusters (AuClusters) are two classes of advantageous nanostructures with special optical properties, and many other attractive properties. Integrating them into one nanosystem may achieve greater and smarter performance. Herein, a hybrid gold nanostructure for fluorescent and optoacoustic tomography imaging, controlled release of drugs, and photothermal therapy (PTT) is demonstrated. For this nanodrug (EA–AB), an epidermal growth factor receptor (EGFR) inhibitor erlotinib (EB) is loaded into AuNCs, which are then capped and functionalized by biocompatible AuCluster@BSA (BSA = bovine serum albumin) conjugates via electrostatic interaction. Upon cell internalization, the lysosomal proteases and low pH cause the release of EB from EA–AB, and also induce fluorescence restoration of the AuCluster for imaging. Irradiation with near‐infrared light further promotes the drug release and affords a PTT effect as well. The AuNC‐based nanodrug is optoacoustically active, and its biodistribution and metabolic process have been successfully monitored by whole‐body and 3D multispectral optoacoustic tomography imaging. Owing to the combined actions of PTT and EGFR pathway blockage, EA–AB exhibits marked tumor inhibition efficacy in vivo.     

医学造影用微泡材料制备方法研究进展

微泡由于其特殊的结构,广泛地应用于食品、化妆品、医学等领域.尤其是在医学超声造影方面的应用,开创了无创超声医学的新领域.而医学造影用微泡材料的制备是一个复杂、有相当难度的过程.微胶囊技术的引入大大加快了微泡造影荆制备方法的发展.对近年来国内外微泡造影剂的各种制备方法及其优缺点进行了介绍.指出采用化学方法能得到更加个性化的声学造影剂,并使其具有成像和靶向治疗的双重功效.