Feasibility study of propagation‐based phase‐contrast X‐ray lung imaging on the Imaging and Medical beamline at the Australian Synchrotron

Propagation‐based phase‐contrast X‐ray imaging (PB‐PCXI) using synchrotron radiation has achieved high‐resolution imaging of the lungs of small animals both in real time and in vivo. Current studies are applying such imaging techniques to lung disease models to aid in diagnosis and treatment development. At the Australian Synchrotron, the Imaging and Medical beamline (IMBL) is well equipped for PB‐PCXI, combining high flux and coherence with a beam size sufficient to image large animals, such as sheep, due to a wiggler source and source‐to‐sample distances of over 137 m. This study aimed to measure the capabilities of PB‐PCXI on IMBL for imaging small animal lungs to study lung disease. The feasibility of combining this technique with computed tomography for three‐dimensional imaging and X‐ray velocimetry for studies of airflow and non‐invasive lung function testing was also investigated. Detailed analysis of the role of the effective source size and sample‐to‐detector distance on lung image contrast was undertaken as well as phase retrieval for sample volume analysis. Results showed that PB‐PCXI of lung phantoms and mouse lungs produced high‐contrast images, with successful computed tomography and velocimetry also being carried out, suggesting that live animal lung imaging will also be feasible at the IMBL.     

红外显微化学图像技术在空心微球制备中的应用

在考察聚苯乙烯(PS)与聚乙烯基苄氯(PVBCl)相容性及干涉效应对测量结果影响的基础上,使用红外显微化学图像技术研究表征了PS与PVBCl混合物薄膜和微球的相分离情况,对比分析了不同处理条件下制备的微球半球壳中两种聚合物的相分离红外显微化学图像。研究结果表明建立的研究方法可以用来定性或半定量的分析球壳内PS和PVBCl两聚合物的分相情况,在测试中样品的干涉效应会对测量造成较大的不确定度,在不同温度下获得的聚合物微球样品中,40℃条件下两聚合物的分相情况更为理想。该研究为探索非均相双半球型聚合物微球制备条件以及红外显微化学图像法表征聚合物相分离提供了一种直观可行的表征方法,但受空间分辨率的影响,该方法不适合于6.25μm×6.25μm以下尺寸样品的分析。     

TOF-SIMS analysis of magnetic materials in chum salmon head

A piece of tissue extracted from a chum salmon Oncorhynchus keta head was measured with time-of-flight secondary ion mass spectrometry (TOF-SIMS) in order to evaluate the distribution and composition of magnetic materials in the tissue, which may concern with geomagnetic navigation of long-distance migrating salmon. Several depositions of iron compounds were detected in the tissue by TOF-SIMS analysis. Comparing with total ion images providing a topological tissue structure, specific distribution of iron ion in the tissue was clearly shown. Higher magnification TOF-SIMS analysis revealed the existence of the aggregations of iron particles. Iron oxide clusters comprising many submicron particles were also detected in the tissue using scanning electron microscopy and X-ray analysis, suggesting the common existence of submicron-scale iron oxides in salmon heads. These results suggest that TOF-SIMS analysis is a valid method to clarify detailed structures and chemical properties of candidate magnetoreceptors in fish heads.     

Recovering of images degraded by atmosphere

Remote sensing images are seriously degraded by multiple scattering and bad weather. Through the analysis of the radiative transfer procedure in atmosphere, an image atmospheric degradation model considering the influence of atmospheric absorption multiple scattering and non-uniform distribution is proposed in this paper. Based on the proposed model, a novel recovering method is presented to eliminate atmospheric degradation. Mean-shift image segmentation and block-wise deconvolution are used to reduce time cost, retaining a good result. The recovering results indicate that the proposed method can significantly remove atmospheric degradation and effectively improve contrast compared with other removal methods. The results also illustrate that our method is suitable for various degraded remote sensing, including images with large field of view (FOV), images taken in side-glance situations, image degraded by atmospheric non-uniform distribution and images with various forms of clouds.     

Use of flow microcalorimetry and dynamic mechanical thermal analysis for probing interphase structure in poly(styrene-b-butadiene-b-styrene)/magnesium hydroxide composites

Interactions between magnesium hydroxide (Mg(OH)₂ particles (both untreated and treated with 16-methyl heptadecanoic acid (isostearic acid)) and low molar mass poly(styrene) (PS) and poly(butadiene) (PB) have been studied by flow microcalorimetry (FMC) and have been related to the interphase structure in poly(styrene-b-butadiene-b-styrene) (SBS)/Mg(OH)₂ composites using dynamic mechanical thermal analysis (DMTA). The FMC studies revealed that both polymers adsorbed strongly onto an untreated magnesium hydroxide surface though the PB showed greater irreversible adsorption from the heptane carrier fluid. Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) studies on filler samples removed from the FMC cell after the adsorption-desorption cycle confirmed strong polymer filler interaction. Adsorption of the low molar mass samples of PS and PB onto a pre-adsorbed monolayer of isostearic acid on Mg(OH)₂ resulted in a very significant reduction in polymer adsorption activity due to blockage of adsorption sites. DMTA studies revealed that strong adsorption of PS and PB blocks of SBS onto untreated filler in composites containing 60% w/w Mg(OH)₂ gave rise to phase mixing that led to an 18 °C reduction in the T _g of the PS phase relative to that in the unfilled matrix. However, in equivalent composites based on isostearic acid treated filler a smaller reduction (10 °C) was observed, therefore reflecting reduced filler-matrix interaction and reduced phase mixing.     

Quantitative analysis of surface amine groups on plasma-polymerized ethylenediamine films using UV-visible spectroscopy compared to chemical derivatization with FT-IR spectroscopy, XPS and TOF-SIMS

A quantitative analysis of the surface density of amine groups on a plasma-polymerized ethylenediamine thin film deposited on a platinum surface using inductively coupled plasma chemical vapor deposition method is described. UV-visible spectroscopy together with a chemical derivatization technique using Fourier transform infrared (FT-IR) spectroscopy was used to obtain the quantitative information. Chemical tags of pentafluorobenzaldehyde were hybridized with the surface amine groups and were easily detected due to the characteristic absorption bands of C-F stretching, aromatic ring and CN stretching vibrations in the reflection-absorption FT-IR spectra. The surface amine density was reproducibly controlled as a function of deposition plasma power and quantified using UV-visible spectroscopy. A good linear correlation was observed between the FT-IR intensities of the characteristic absorption bands and the surface amine densities, suggesting the possibility of using this chemical derivatization technique to quantify the surface densities of specific functional groups on an organic surface. Chemical derivatization was also used with X-ray photoelectron spectroscopy on the same samples, and the results were compared with those obtained from FT-IR and time-of-flight secondary ion mass spectrometry. Although each analysis technique has different probing depths from the surface, the three different data sets obtained from the chemical tags correlated well with each other since each analysis technique measured the chemical tags on the sample surface.     

The analysis of alkyl-capped alcohol ethoxylates and alcohol ethoxycarboxylates from alcohol ethoxylates by atmospheric pressure chemical ionization mass spectrometry

Alcohol ethoxylates (AEs) are nonionic surfactants. They are industrially important compounds that have historically been difficult to analyze, with the best results to date achieved through derivatization (e.g., silylation) followed by analysis by gas chromatography/mass spectrometry (GC/MS). Recently, mass spectrometric techniques such as field desorption (FD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) have been employed to analyze surfynol(R) 4xx. In an effort to produce low-cost alkyl-capped AEs and anionic detergents from AEs, a fast and reliable measure of the product yields and conversions from AEs is required in research. We found that the product yields and conversions from reactions of AEs, obtained by the employment of atmospheric pressure chemical ionization (APCI), were in good agreement with those obtained from proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Therefore, APCI can be used as a validated tool for studying AE reactions. Mixtures that contain either silylated or unsilylated ethoxylates and/or carboxylates yield the same APCI mass spectra. Copyright -Copyright 1999 John Wiley & Sons, Ltd.     

基于相位一致性和Hough变换的多源图像配准方法

由于红外图像与可见光图像对比度不同,常用基于梯度幅值的特征匹配方法难以正确配准。在分析红外图像与可见光图像成像机制的基础上,提出了一种结合相位一致性边缘检测与Hough变换的多源图像配准新方法。该算法首先采用高通滤波和平台直方图均衡方法对红外图像进行预处理以提高红外图像的对比度,再利用具有图像对比度不变性的相位一致性边缘检测法提取两幅图像的边缘,结合Hough变换选取图像空间中最长的线作为特征,采用改进相位相关法作为相似性度量,在对数极坐标域下计算出两幅图像的几何变形参数。仿真实验结果表明,该方法能够以较高查准率实现红外与可见光图像自动配准,并具有较强的鲁棒性。     

X-ray phase-attenuation duality and phase retrieval

Phase retrieval is the key to quantitative x-ray phase-contrast imaging. To retrieve the phase image of an x-ray wave field, in general one needs multiple phase-contrast images. We have made a new observation of phase-attenuation duality for soft tissues, and we show how only a single phase-contrast image is needed for successful phase retrieval based on this duality. The phase-retrieval formula based on a single phase-contrast image of inhomogeneous soft tissue is derived and presented. We show the striking enhancement of the tissue contrast in simulated phase images that this new approach produces.     

Mutual information theory for biomedical applications: Estimation of three protein-adsorbed dialysis membranes

Protein-adsorbed dialysis membranes are evaluated with time-of-flight secondary ion mass spectrometry (TOF-SIMS) chemical imaging technique. Protein adsorption causing permeability change is one of big issues in the development of dialysis membranes. Bovine serum albumin adsorption onto three kinds of dialysis membranes has been evaluated with TOF-SIMS. In the present study three kinds of proteins, bovine serum albumin, α-chymotripsinogen A, and cytochrome C adsorbed onto hollow-fiber dialysis membranes, were measured by means of TOF-SIMS and then TOF-SIMS spectra were analyzed using mutual information. Then specific peaks of fragment ions related to α-chymotripsinogen A and bovine serum albumin were found, respectively. In this condition, however, specific peaks to cytochrome C were not able to find compared with other samples. Finally, chemical images of α-chymotripsinogen A and bovine serum albumin, respectively, adsorbed onto the membranes with co-existing proteins were obtained. The results of TOF-SIMS images of the proteins on the membranes show different tendency of adsorption depending on co-existing proteins. Further study is needed to study more detailed protein adsorption onto the membranes with co-existing proteins.     

Quantitative phase retrieval in X‐ray Zernike phase contrast microscopy

In recent years, increasing attention has been devoted to X‐ray phase contrast imaging, since it can provide high‐contrast images by using phase variations. Among the different existing techniques, Zernike phase contrast microscopy is one of the most popular phase‐sensitive techniques for investigating the fine structure of the sample at high spatial resolution. In X‐ray Zernike phase contrast microscopy, the image contrast is indeed a mixture of absorption and phase contrast. Therefore, this technique just provides qualitative information on the object, which makes the interpretation of the image difficult. In this contribution, an approach is proposed for quantitative phase retrieval in X‐ray Zernike phase contrast microscopy. By shifting the phase of the direct light by π/2 and 3π/2, two images of the same object are measured successively. The phase information of the object can then be quantitatively retrieved by a proper combination of the measured images. Numerical experiments were carried out and the results confirmed the feasibility of the proposed method. It is expected that the proposed method will find widespread applications in biology, materials science and so on.     

A method for automatic identification of water and fat images from a symmetrically sampled dual-echo Dixon technique

Sampling water and fat signals symmetrically (i.e., at 0° and 180° relative phase angles) in a dual-echo Dixon technique offers high intrinsic tolerance to phase fluctuations in postprocessing and maximum signal-to-noise performance for the separated water and fat images. However, identification of which image is water and which image is fat after their separation is not possible based on the phase information alone. In this work, we proposed a semiempirical automatic image identification method that is based on the intrinsic asymmetry between the water and fat chemical shift spectra. Specifically, the approximately bimodal feature of the fat spectra and the observation that most in vivo tissues are either predominantly water or predominantly fat are used to construct a spectrum-based algorithm. Additional refinement is accomplished by considering the spatial distribution of the tissues that may have a coexistence of water and fat. The final improved algorithm was tested on a total of 131 three-dimensional patient datasets collected from different scanners and found to yield correct water and fat identification in all datasets.     

飞秒激光光斑灰度与几何特征的相关性分析

飞秒激光烧蚀单晶硅的加工过程中，CCD相机采集的光斑图像中有效灰度区域与背景难以区分。为了解决这一问题，提出一种主成分分析与限制对比度自适应直方图均衡化相结合的方法，对光斑图像进行增强处理，再提出去趋势互相关分析法对光斑序列图像的灰度特征与几何特征进行长程相关性分析。结果表明，光斑序列图像的灰度特征与光斑纹理对比度、光斑面积具有较强的长程相关性，与纹理同质性表现出较强的反相关关系，可根据这3项与灰度特征较强的相关关系对后续微槽加工过程中的灰度特征进行预测。     

Three-dimensional visualization of objects in scattering medium using integral imaging and spectral analysis

This paper presents a three-dimensional visualization method of 3D objects in a scattering medium. The proposed method employs integral imaging and spectral analysis to improve the visual quality of 3D images. The images observed from 3D objects in the scattering medium such as turbid water suffer from image degradation due to scattering. The main reason is that the observed image signal is very weak compared with the scattering signal. Common image enhancement techniques including histogram equalization and contrast enhancement works improperly to overcome the problem. Thus, integral imaging that enables to integrate the weak signals from multiple images was discussed to improve image quality. In this paper, we apply spectral analysis to an integral imaging system such as the computational integral imaging reconstruction. Also, we introduce a signal model with a visibility parameter to analyze the scattering signal. The proposed method based on spectral analysis efficiently estimates the original signal and it is applied to elemental images. The visibility-enhanced elemental images are then used to reconstruct 3D images using a computational integral imaging reconstruction algorithm. To evaluate the proposed method, we perform the optical experiments for 3D objects in turbid water. The experimental results indicate that the proposed method outperforms the existing methods.     

磷烧伤的31P NMR研究

为了明确磷烧伤创面及吸收毒性物质的化学形式及分布.作者采用³¹P PNMR波谱,研究皮下注射黄磷、磷酸及磷烧伤后创面残留、肝脏及脑组织吸收的元素磷及其化合物含量.其结果皮下注射非致死与致死剂量的黄磷后,肝脏可测到元素磷的吸收,磷燃烧后创面磷绝大部分转化为磷酸及其结合物,极少部分以元素磷形式存在.致死面积的磷酸烫伤与磷烧伤后肝脏区域磷酸增加4~5倍,未检测到元素磷的波谱,各组脑组织均未检测到元素磷峰,而磷酸峰只有微小的增加.结论为磷烧烧后吸收的主要中毒物质与创面残留的主要化学物质一致,磷烧伤中毒的致死性主要是创面磷酸吸收所致.     

ASAP模拟变焦系统中鬼像的研究

 非成像光束在光学系统内表面的多次折射反射容易在像面附近形成光晕或鬼像,变焦系统由于镜片多,机构复杂等往往难以进行全面的分析模拟。利用ASAP软件模拟每个透射面作为部分透射、部分反射的表面,对变焦光学系统非轴上光进行分析,模拟出变焦系统的光学元件表面和光机内壁,实行实际光线追迹,然后以像面为研究对象,进一步实施实际光线追迹,模拟出全部散射光在像面上的能量分布,找出鬼像形成的原因,并在此基础上通过改变二次反射所在面的曲率或改变所在面的折射率两种方法对变焦光学系统进行优化,减小鬼点数目,以提高系统的成像质量。     

THE 31P NMR INVESTIGATION OF PHOSPHORUS BURNS

为了明确磷烧伤创面及吸收毒性物质的化学形式及分布.作者采用\+\{31\}P NMR波谱,研究皮下注射黄磷、磷酸及磷烧伤后创面残留、肝脏及脑组织吸收的元素磷及其化合物含量.其结果皮下注射非致死与致死剂量的黄磷后,肝脏可测到元素磷的吸收,磷燃烧后创面磷绝大部分转化为磷酸及其结合物,极少部分以元素磷形式存在.致死面积的磷酸烫伤与磷烧伤后肝脏区域磷酸增加4～5倍,未检测到元素磷的波谱,各组脑组织均未检测到元素磷峰,而磷酸峰只有微小的增加.结论为磷烧烧后吸收的主要中毒物质与创面残留的主要化学物质一致,磷烧伤中毒的致死性主要是创面磷酸吸收所致.     

STRUCTURE-PROPERTY RELATIONS IN REACTION-INDUCED,PHASE-SEPARATED POLY(2-PHENOXYETHYL ACRYLATE)/POLYSTYRENE BLENDS

Structure-property relations were studied in reaction-induced, phase-separated polymer blends. An amorphous-amorphous system consisted of polystyrene (PS) dissolved in the monomer 2-phenoxyethyl acrylate (POA). When the POA was polymerized to poly(2-phenoxyethyl acrylate) (PPOA), phase separation and phase inversion were induced, and a polymer blend was formed. The reaction kinetics were measured by monitoring the reduction in the intensity of the C╤C stretching vibration band in the Raman spectrum of POA. The phase separation kinetics were determined using light transmission experiments and were combined with the reaction kinetics so that a ternary phase diagram could be defined for the reactive system. Structure development was monitored using small-angle laser light scattering (SALLS) and optical microscopy, which showed that spinodal decomposition was the mechanism of liquid-liquid phase separation. Plots of the relative invariant with time showed an increase in the degree of phase separation. The Fourier transforms of the microscopy images had peaks in the radial intensity distributions, again implying that spinodal decomposition was the phase separation mechanism. Tensile testing showed that PPOA was soft and rubbery at 20°C. Both PS and PPOA had comparable toughness when tested to failure; however, the blend containing 17 wt% PS had a toughness more than 10 times that of either PS or PPOA in isolation. Both modulus and tensile strength increased with PS content, while the ultimate strain decreased. The Nielsen model best described the tensile modulus data, providing further evidence for co-continuous phase structure.