新型感光影象微结构分析系统研制

本世纪50年代,Schade等人将Fourver分析方法用于照相过程,建立了感光材料清晰性的调制传递函数评价方法。根据感光材料调制传递函数理论,美国柯达公司于60年代建立了感光材料调制传递测试方法,即正弦调制传递函数测试法,70年代被定为国家标准。     

0.6~T人体核磁共振成象及其图象的彩色化处理

在0.6~τ超导磁体人体核磁共振成象设备上获得了横断、矢状、冠状各种断层的成象。采用了直接两维傅里叶变换成象方法,应用了自旋回波脉冲序列。由于人体心脏跳动和呼吸运动会造成图象模糊而使用心电延迟触发及呼吸门控方法。作者用一种相位调制光密度分割的方法将原始黑白灰度表示的核磁共振成象进行彩色化处理。提高了原图象低密度梯度区的清晰度,为进行医学图象诊断及判读解译提供了方便度。山了光学系统图,解释了光学信息处理方法。由所处理的人体核磁共振成象图片可以看出,在低密度梯给区更易辨认。参考文献10种。     

信息与服务

蓝色氧化钨的制备采用内在还原法制备蓝色氧化钨为国内首创,产品化学纯度高、比表面大、粒度均匀。TOD 法测定污水含氧量用总需氧量评价水质     

广义Gabor函数模型和感受野某些特性曲线的模拟

本文提出用一族广义Gabor函数作为视觉系统初级信息加工的权函数,对视皮层的简单细胞、复杂细胞和某些超复杂细胞的取向调谐曲线、长度调谐曲线和空间频率调制曲线进行模拟计算,取得良好结果。本文认为广义Gabor函数模型能较好地描述视觉系统各级水平上感受野的主要性质。     

激光打印技术用改性PVK—TeNF光导材料

一、引言新一代的带有计算机控制,数字扫描,激光成象的激光印刷系统,引起了各方面极大的关注,该系统具有图象质量好,印刷速度快,版面可任意安排和调制的优点,而且体积小巧,还可实现台面印刷,一般还可直接印刷在普通纸张上,印刷速度可达120—300页/分。其印刷质量高,分辨率达600点/英寸,远高于常规印刷技术的质量,工作时噪音也小,且具有多功能印刷效果。这种新的激光印刷体系的版材所     

论骑行波——Ⅰ.波动不稳定性和频率调制

本文给出了骑行波在流线曲线坐标中的一种较完整的描述,由不稳定性分析所导出的色散关系依赖于背景场的表面速度散度、旋度、变形率和主波面的曲率等。骑行波的不稳定性和频率调制是有选择的和分片的。这些理论结果已为实验测量所佐证,是微波遥感器的重要成象机理。     

不同炮制工艺麦冬总皂苷含量与活性评价

根据《中国药典》和参考文献所述炮制方法,对麦冬进行抽心、轧扁(捣裂)、整粒和切片炮制处理,提取分离其总皂苷,并开展体外抑菌活性评价。结果表明:不同炮制工艺麦冬皂苷提取率从高到低的顺序为整粒>抽心>轧扁、切片;4种炮制品的麦冬皂苷类成分对大肠杆菌和金黄色葡萄球菌均有较强的抑菌效果,其中整粒的效果最佳。考察不同麦冬炮制品提取总皂苷含量与抑菌率的相关性研究,发现整粒炮制工艺具有提取率高、工艺稳定性、体外抑菌活性高和生产成本低的优点,可为麦冬炮制工艺的筛选提供参考。     

基于SnO2气体传感器农药残留的动态检测及定性定量分析

研究了一种快速检测和识别农药敌百虫、乙酰甲胺磷气体新方法,即动态俭测方法：这种方法利用单个SnO2气体传感器而非阵列在方波温度调制的状态下可实现两种农药气体的定性分析,实验结果表明、在0．02Hz的调制频率、250～300℃的温度调制范围,传感器对单一组分的农药残留表现出高的选择性和稳定性;利用FFT频谱和极坐标构建完成对敌百虫和乙酰甲胺磷的定性和定量分析。     

末端含蓝光发色团的超支化聚苯材料的合成

在聚合物发光材料研究领域中,作为三元色之一的蓝色发光材料的设计与合成倍受关注．一维线型结构的聚对苯及聚烷基芴等是典型的蓝色发光材料;线型结构的聚对亚苯亚乙烯基(PPV)及聚对亚苯亚乙炔基(PPE)具有电子流动性好,在溶液中有高荧光量子效率也可衍生得到蓝色发光材料,这主要是在共轭聚合物主链上嵌入非共轭部分,     

ZAA仪器的信噪比特性研究

塞曼效应背景校正装置在AAS中得到了广泛的应用,许多研究工作者不断地研究和制成了各种调制方式的ZAA仪器。文献[1]和[2]分别对各种实验装置和商品仪器作了评价。横向恒定磁场置于原子化器的ZAA商品仪器最多。这种方式必须采用P_H和P_L调制,即偏振分离调制。这种调制还可以多种方式实现,并且显示了不同的信噪比特性。     

Slot scintillation detector modeling for digital radiography

A scanning slot X-ray digital detector operating at relatively high photon energies, mainly 70 kVp for dental radiography, has been designed and modeled. In this energy range, further improvements are required in order to attain optimal image quality for the lowest achievable mean absorbed dose to the patient. This paper concerns the investigation of the physics of imaging using a structured screen composed of a scintillating fiber optic (LKH-6/CCD system) and its performance by Monte Carlo (MC) simulation. The A_s factor, X-ray cross-talk, quantum noise effect on resultant values of Detective Quantum Efficiency (DQE) and Modulation Transfer Function (MTF) are discussed. The results of this paper should serve as a useful guide in the engineering design of future structured screen/CCD based systems.     

Design, testing and optimization of a neutron radiography system based on a Deuterium–Deuterium (D–D) neutron generator

Simulations show that significant improvement in imaging performance can be achieved through collimator design for thermal and fast neutron radiography with a laboratory neutron generator. The radiography facility used in the measurements and simulations employs a fully high-voltage-shielded, axial D–D neutron generator with a radio frequency driven ion source. The maximum yield of such generators is about 10¹⁰ fast neutrons per seconds (E = 2.45 MeV). Both fast and thermal neutron images were acquired with the generator and a Charge Coupled Devices camera. To shorten the imaging time and decrease the noise from gamma radiation, various collimator designs were proposed and simulated using Monte Carlo N-Particle Transport Code (MCNPX 2.7.0). Design considerations included the choice of material, thickness, position and aperture for the collimator. The simulation results and optimal configurations are presented.     

纳米金红石型TiO2催化超声降解亚甲基蓝溶液

水溶性染料是印染工业中污染治理的主要对象，由于它们大多含有苯环，目前所使用的化学和生物等处理方法效果均不佳。而以半导体为催化剂的光催化处理方法对单一染料和实际印染废水处理效果较好。本文采用高温处理过的纳米TiO2作催化剂对亚甲基蓝溶液进行降解，大大缩短了降解时间，提高了降解率，60min降解率即可达66．8％，120min降解率则可达80％以上。而且发现利用超声波来替代紫外光对亚甲基蓝进行降解时，     

Design and simulation of neutron radiography system based on 241Am–Be source

Neutron imaging is extended rapidly as a means of non-destructive testing (NDT) of materials. Various effective parameters on the image quality are needed to be studied for neutron radiography system with good resolution. In the present study a portable system of neutron radiography has been designed using ²⁴¹Am–Be neutron source. The effective collimator parameters were calculated to obtain relatively pure, collimated and uniform neutron beam. All simulations were carried out in two stages using MCNPX Monte Carlo code. In the first stage, different collimator configurations were investigated and the appropriate design was selected based on maximum intensity and uniformity of neutron flux at the image plane in the outlet of collimator. Then, the overall system including source, collimator and sample was simulated for achieving radiographic images of standard samples. Normalized thermal neutron fluence of 2.61×10^?5 cm^?2 per source particle with n/γ ratio of 1.92×10⁵ cm^?2 μSv^?1 could be obtained at beam port of the designed collimator. Quality of images was assessed for two standard samples, using radiographic imaging capability in MCNPX. The collimated neutron beam in the designed system could be useful in a transportable exposure module for neutron radiography application.     

A FLUORESCENCE IMAGING DEVICE FOR ENDOSCOPIC DETECTION OF EARLY STAGE CANCER – INSTRUMENTAL and EXPERIMENTAL STUDIES

Abstract Visible detection of early stage cancer labelled with the fluorescing porphyrin mixture of dihematoporphyrin-ether and dihematoporphyrin-ester (DHE) is often limited by a high and inhomogeneously distributed level of autofluorescence. A new imaging method for reducing autofluo-rescence is described. The method uses alternating fluorescence excitation with laser light in the violet and blue spectral ranges. Subtraction of the corresponding fluorescence images results in contrast enhancement due to an effective reduction in the autofluorescence contribution. A prototype version of a highly sensitive fluorescence imaging device including a modified krypton ion laser, an image-intensified solid-state TV-camera, a digital image-processing system, and video recording and monitoring has been developed.
Experiments performed with this fluorescence imaging system on a tumorous dog bladder showed that a dose of 0.2 mg DHE kg⁻¹ body wt, which is far below the dose administered for photodynamic therapy (2-5 mg kg⁻'body wt), is sufficient to give a high-contrast fluorescence image. The corresponding excitation power density was about 1 W m⁻². Photobleaching of DHE was observed during fluorescence detection at excitation power densities exceeding 1 kW m⁻². At these high excitation levels DHE fades out nearly completely within 0.25 min.     

Experimental considerations of myocardial single photon emission CT image with a cardiac phantom

We studied the quantity of thallium-201 myocardial single photon emission CT (SPECT) image with a cardiac phantom. The myocardial SPECT image is influenced by several causes, i.e., the absorption of gamma rays, collimator aperture, statistical noise and limited angle of rotation in data acquisition. The attenuation correction under the assumption of uniform distribution is not sufficient, so we have to consider the actual distribution of absorption. The effects of the nonuniform attenuation are most prominently appeared when we evaluate the quantity by the integral method. The aperture characteristics of a collimator are decided by the distance between the rotational center of the gamma camera and the collimator surface. Simultaneously scattered gamma rays affect the reconstructed image in the low frequency component, so the effective attenuation coefficient varies gradually. The statistical noise intermixed in the projection data generate artifacts like as lump-shaped pattern. The noise are clearly appeared in the spatial frequency upper than 0.25 cycle, so the low-pass filter are required with that of cut-off frequency. Moreover to enhance the details of the radionuclide distribution of cardiac muscle, the Wiener filter should be applied. The scan area also affects the appearance of the artifact in the myocardial SPECT image. The 180-degree scan usually generates false defects just nearby the center of reconstructed cross section. And the positions are changed with the conditions of gamma ray absorber and its relative position to the myocardial area. The 360-degree scan should be used from the standpoint of reconstructing more quantitative image.     

Blue silver: a very sensitive colloidal Coomassie G-250 staining for proteome analysis

A modified Neuhoff's colloidal Coomassie Blue G-250 stain is reported, dubbed "blue silver" on account of its considerably higher sensitivity, approaching the one of conventional silver staining. The main modifications, as compared to Neuhoff's protocol, were: a 20% increment in dye concentration (from 0.1% up to 0.12%) and a much higher level of phosphoric acid in the recipe (from 2% up to 10%). The "blue silver" exhibits a much faster dye uptake (80% during the first hour of coloration, vs. none with a commercial preparation from Sigma). Even at equilibrium (24 h staining), the "blue silver" exhibits a much higher sensitivity than all other recipes, approaching (but lower than) the one of the classical silver stain. Measurements of stain sensitivity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of bovine serum albumin (BSA) gave a detection limit (signal-to-noise ratio > 3) of 1 ng in a single zone. The somewhat lower sensitivity of "blue silver" as compared to classical silvering protocols in the presence of aldehydes is amply compensated for by its full compatibility with mass spectrometry of eluted polypeptide chains, after a two-dimensional map analysis, thus confirming that no dye is covalently bound (or permanently modifies) to any residue in the proteinaceous material. It is believed that the higher level of phosphoric acid in the recipe, thus its lower final pH, helps in protonating the last dissociated residues of Asp and Glu in the polypeptide coils, thus greatly favoring ionic anchoring of dye molecules to the protein moiety. Such a binding, though, must be followed by considerable hydrophobic association with the aromatic and hydrophobic residues along the polypeptide backbone.     

Fully automated measurement of the modulation transfer function of charge-coupled devices above the Nyquist frequency

The charge-coupled devices used in electron microscopy are coated with a scintillating crystal that gives rise to a severe modulation transfer function (MTF). Exact knowledge of the MTF is imperative for a good correspondence between image simulation and experiment. We present a practical method to measure the MTF above the Nyquist frequency from the beam blocker's shadow image. The image processing has been fully automated and the program is made public. The method is successfully tested on three cameras with various beam blocker shapes.     

Silver‐Doped TiO2‐Coated Cotton Fabric as an Effective Photocatalytic System for Dye Decolorization in UV and Visible Light

In this study, titanium tetra‐isopropoxide was used as a precursor of TiO₂ for in situ coating on cotton fabric by sol–gel method. Subsequently, silver nitrate was used as doping agent to prepare silver‐doped TiO₂‐coated cotton fabric during hydrothermal treatment. The treated samples were characterized through field‐emission scanning electron microscopy, energy‐dispersive X‐ray analysis, inductively coupled plasma‐mass spectroscopy and UV–visible absorption spectroscopy to study morphology, composition of deposited elements and light absorption behavior of treated samples. X‐ray photoelectron spectroscopy was carried out to analyze the electronic state of silver in TiO₂‐coated fabric after hydrothermal treatment. Doping of silver on TiO₂‐coated fabric and subsequent hydrothermal treatment was found to enhance dye decolorization rate of rhodamine B dye solution in both UV and visible light radiations with respect to undoped TiO₂. The study shows that an optimal level of silver‐doped TiO₂‐coated fabric can be used repeatedly for dye decolorization without significant loss in its photocatalytic activity. The self‐cleaning properties of samples were also studied using methylene blue as a staining agent. It was observed that the presence of 1.8% silver on the weight of titanium in doped samples provides almost 82% of stain degradation.     

Mn(II)-Fe(II)-MCF的制备及催化性能

以改性玉米苞叶纤维为载体(MCF),负载Mn(II)和Fe(II)制备了Mn(II)-Fe(II)-MCF复合材料,催化H₂O₂氧化水中染料。通过傅立叶变换红外/近红外成像系统和扫描电子显微镜对其结构和形貌进行表征。实验结果表明:当染料浓度为10 mg·L^-1,Mn(II)-Fe(II)-MCF用量为4 g·L^-1,H₂O₂初始浓度为1.56 mmol·L^-1,Mn(II)-Fe(II)-MCF对四种染料的催化效率明显不同。阳离子蓝X-GRRL(CBX-GRRL)降解效果最好,其次是甲基橙(MO)、次甲基蓝(MB)和罗丹明B(RhB)。对染料的氧化反应进行动力学分析,MO的降解反应为二级反应,CBX-GRRL、MB和RhB的降解反应均为一级反应。Mn(II)-Fe(II)-MCF适合催化氧化偶氮染料废水。