X-ray tomography

X射线断层扫描
  • 文章类型: Journal Article
    冻干物的拓扑结构和表面特性显著影响冻干药物的稳定性和可重构性。因此,产品的视觉质量控制势在必行。然而,此过程不仅耗时耗力,而且昂贵且容易出错。在本文中,我们提出了一种完全自动化的方法,冻干药品的无损检测,利用机器人技术,计算机断层扫描,和机器学习。
    The topology and surface characteristics of lyophilisates significantly impact the stability and reconstitutability of freeze-dried pharmaceuticals. Consequently, visual quality control of the product is imperative. However, this procedure is not only time-consuming and labor-intensive but also expensive and prone to errors. In this paper, we present an approach for fully automated, non-destructive inspection of freeze-dried pharmaceuticals, leveraging robotics, computed tomography, and machine learning.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    来自区域检测器的单晶X射线衍射数据的处理可以分为两个步骤。首先,原始强度通过衍射图像的积分获得,然后进行数据校正和还原以确定结构因子的振幅及其不确定性。第二步考虑衍射几何形状,样品照明,衰变,吸收和其他影响。虽然吸收在标准大分子晶体学(MX)中只是次要影响,它可能成为长波长实验的最大不确定性来源。当前的MX软件包通常采用经验模型来校正吸收的影响,通过最小化对称等效反射之间的强度差异来确定校正;这些模型非常适合捕获平滑变化的实验效果。然而,对于非常长的波长,经验方法成为一种不可靠的方法来模拟高保真度的强吸收效应。当数据多重性低时,这个问题尤其严重。本文提出了一种基于X射线断层扫描得出的样品体积模型的分析吸收校正策略(在新软件AnACor中实现)。对于所有反射,通过不同样品材料的各个路径长度由光线跟踪方法确定。吸收校正的几种方法(球面谐波校正,分析吸收校正和两者的组合)对两个样品进行比较,膜蛋白OmpK36GD,在λ=3.54的波长下测量,和亚氯酸盐歧化酶,在λ=4.13µ下测量。数据集统计,反常差分傅立叶图中的峰高和实验定相成功用于比较不同吸收校正方法的结果。使用新的分析吸收校正的策略被证明优于标准的球面谐波校正。虽然在3.54的数据中改善不大,在较长波长数据中,分析吸收校正优于球面谐波(λ=4.13µ),这也反映在成功的实验阶段所需的数据量减少。
    Processing of single-crystal X-ray diffraction data from area detectors can be separated into two steps. First, raw intensities are obtained by integration of the diffraction images, and then data correction and reduction are performed to determine structure-factor amplitudes and their uncertainties. The second step considers the diffraction geometry, sample illumination, decay, absorption and other effects. While absorption is only a minor effect in standard macromolecular crystallography (MX), it can become the largest source of uncertainty for experiments performed at long wavelengths. Current software packages for MX typically employ empirical models to correct for the effects of absorption, with the corrections determined through the procedure of minimizing the differences in intensities between symmetry-equivalent reflections; these models are well suited to capturing smoothly varying experimental effects. However, for very long wavelengths, empirical methods become an unreliable approach to model strong absorption effects with high fidelity. This problem is particularly acute when data multiplicity is low. This paper presents an analytical absorption correction strategy (implemented in new software AnACor) based on a volumetric model of the sample derived from X-ray tomography. Individual path lengths through the different sample materials for all reflections are determined by a ray-tracing method. Several approaches for absorption corrections (spherical harmonics correction, analytical absorption correction and a combination of the two) are compared for two samples, the membrane protein OmpK36 GD, measured at a wavelength of λ = 3.54 Å, and chlorite dismutase, measured at λ = 4.13 Å. Data set statistics, the peak heights in the anomalous difference Fourier maps and the success of experimental phasing are used to compare the results from the different absorption correction approaches. The strategies using the new analytical absorption correction are shown to be superior to the standard spherical harmonics corrections. While the improvements are modest in the 3.54 Å data, the analytical absorption correction outperforms spherical harmonics in the longer-wavelength data (λ = 4.13 Å), which is also reflected in the reduced amount of data being required for successful experimental phasing.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    普遍认为橡胶的机械响应仅是施加应变的函数。使用创新的X射线测量捕获三维空间体积应变场,我们证明,橡胶和许多常见的工程聚合物经历显著的局部体积变化。但值得注意的是,无论施加的载荷如何,总试样体积保持恒定。这种奇怪的行为也会导致明显的负局部体模量,这是由于这些材料中存在流动相。将X射线断层摄影观察与高速射线照相相结合,以跟踪流动相的运动,我们修改了橡胶弹性的经典热力学框架。这项工作不仅为了解橡胶的机械行为,而且为了解大量广泛使用的工程聚合物开辟了广阔的途径。
    The mechanical response of rubbers has been ubiquitously assumed to be only a function of the imposed strain. Using innovative X-ray measurements capturing the three-dimensional spatial volumetric strain fields, we demonstrate that rubbers and indeed many common engineering polymers undergo significant local volume changes. But remarkably, the overall specimen volume remains constant regardless of the imposed loading. This strange behavior which also leads to apparent negative local bulk moduli is due to the presence of a mobile phase within these materials. Combining X-ray tomographic observations with high-speed radiography to track the motion of the mobile phase, we have revised classical thermodynamic frameworks of rubber elasticity. The work opens broad avenues to understand not only the mechanical behavior of rubbers but a large class of widely used engineering polymers.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    太空应用中使用的电池可能会暴露在大的温度波动下。在这些大的温度波动期间,电池电解质可以经历从液体到固体再回到液体的相变。溶剂的性质和盐的类型影响结晶过程。在这里,我们的目标是了解电极受限区域的压力是如何积累的(例如,孔)影响经历冻融动力学的氧化硅石墨阳极的降解过程。我们的结果表明,高孔隙率电极导致电解质结晶的成核位点密度更高。在暴露于极端温度波动的电池中,孔隙处的局部压力积聚导致活性材料损失和循环寿命降低。
    Batteries used in space applications can be exposed to large temperature-swings. During these large temperature-swings, the battery electrolyte can undergo a phase transformation from a liquid to a solid and back to a liquid. The nature of the solvent and the type of salt influence the crystallization processes. Herein, we aim to understand how pressure build-up in confined regions of an electrode (e.g., pores) influences degradation processes in silicon-oxide graphite anodes undergoing freeze-thaw dynamics. Our results show that high porosity electrodes lead to a greater density of nucleation sites for electrolyte crystallization. Local pressure build-up at pores results in active material loss and decreased cycle lifetime in batteries exposed to extreme temperature swings.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Case Reports
    肺放线菌病是一种罕见的感染性疾病,由于非特异性影像学异常以及需要通过CT引导的活检或支气管镜反复进行肺部采样,因此难以诊断。它可能会出现咯血,有或没有抗生素治疗,可能需要支气管动脉栓塞。我们在这里报告一例肺部放线菌病,胸部CT成像,数字减影血管造影,和病理标本。
    Pulmonary actinomycosis is a rare infectious disease that can be difficult to diagnose due to nonspecific imaging abnormalities and to a need for repeated lung sampling by CT-guided biopsy or bronchoscopy. It may present with hemoptysis, which can occur with or without antibiotic therapy and bronchial artery embolization may be required. We report here a case of pulmonary actinomycosis with imaging by thoracic CT, digital subtraction angiography, and pathological specimens.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    纳米碳聚合物中分形微观结构的原位研究是其应用和改善其功能性能的实际任务。本文介绍了使用脉冲声学显微镜和同步加速器X射线显微断层扫描对复合材料的整体结构特征的可视化。本文介绍了使用不同尺寸和形状的碳颗粒形成分形结构的细节-剥离石墨,碳片和纳米管。复合材料的单个结构元素,即,空气胶囊中颗粒的聚集以及它们在复合体积中的分布,在微观和纳米尺度上观察到。我们已经考虑了颗粒结构对复合材料的分形形成和弹性性能的影响。比较声学和X射线成像结果以验证碳团聚。
    The in situ study of fractal microstructure in nanocarbon polymers is an actual task for their application and for the improvement in their functional properties. This article presents a visualization of the bulk structural features of the composites using pulsed acoustic microscopy and synchrotron X-ray microtomography. This article presents details of fractal structure formation using carbon particles of different sizes and shapes-exfoliated graphite, carbon platelets and nanotubes. Individual structural elements of the composite, i.e., conglomerations of the particles in the air capsule as well as their distribution in the composite volume, were observed at the micro- and nanoscale. We have considered the influence of particle architecture on the fractal formation and elastic properties of the composite. Acoustic and X-ray imaging results were compared to validate the carbon agglomeration.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    沙漠蝗虫Schistocercagregaria的下颌骨(福尔斯克,1775)是挖掘机-铲形的口器,是蝗虫外骨骼的一部分,由昆虫角质层形成。角质层是聚合物纤维复合材料,支持,包住并保护整个身体。下颌骨由于直接接触坚硬和磨蚀的食物而承受沉重的负荷和磨损,就像牙齿一样,它们在脊椎动物中的矿化类似物。双能X射线断层摄影,我们在下颌骨切割边缘对富含锌(Zn)的角质层进行了明确的成像,并量化了这些区域中的Zn浓度。已知锌可以增加刚度,其他纯聚合物昆虫表皮的硬度和耐磨性。在S.Gregaria,富锌切削刃区域相对于彼此的位置表明下颌骨形成剪刀状切削工具,在喂食过程中,当口器相互剪切时,它会变尖。将这些纯聚合物下颌骨的结构与啮齿动物的矿化门牙进行比较,我们发现刀具结构和性能的基本设计差异。蝗虫“剪刀”和啮齿动物“雕刻刀”具有不同的功能,因为它们作用于性质和形状显著不同的食物:更软,在蝗虫的情况下是片状材料,在啮齿动物的情况下是较硬的散装材料。
    The mandibles of the desert locust Schistocerca gregaria (Forsskål, 1775) are digger-shovel-shaped mouthparts that are part of the locust\'s exoskeleton formed by the insect cuticle. The cuticle is a polymer-fibre composite, which supports, encases and protects the entire body. Mandibles experience heavy loading and wear due to direct contact with hard and abrasive food, just like teeth, their mineralized analogues in vertebrates. With dual-energy X-ray tomography, we image well-defined regions of zinc (Zn)-enriched cuticle at the mandible cutting edges and quantify the Zn concentrations in these regions. Zn is known to increase stiffness, hardness and wear resistance of the otherwise purely polymeric insect cuticle. In S. gregaria, the position of the Zn-enriched cutting-edge regions relative to one another suggests that the mandibles form a scissor-like cutting tool, which sharpens itself as the mouthparts shear past one another during feeding. Comparing the architecture of these purely polymeric mandibles with the mineralized incisors of rodents, we find fundamental design differences in cutting-tool structure and performance. Locusts\' scissors and rodents\' carving knives perform different functions, because they act on food that differs significantly in properties and shape: softer, sheet-like material in the case of locusts and harder bulk material in the case of rodents.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    跟随快速,但独立,X射线光谱和相衬系统的扩散,这项工作展示了通过使用边缘照明技术和CdTe小像素(62μm)光谱探测器获得的光谱和相衬计算机断层扫描(CT)的第一个组合。介绍了一种理论模型,从基于标准衰减的光谱分解开始,并导致光谱相衬材料分解。在模型的每个步骤之后,都要对包含已知浓度的不同溶液的测试体模的实验数据进行准确性和灵敏度的量化。报道了在碘-perfusedex病毒蛋白模型上应用微CT(20μm体素大小)的示例。这项工作表明,光谱相衬结合了光谱成像的优点,即高Z材料辨别能力,和相衬成像,即软组织敏感性,同时产生水的质量密度图,钙,碘的准确度为1.1%,3.5%,和1.9%(均方根误差),分别。结果还显示,与标准频谱分解相比,水通道的信噪比增加了9倍。在鼠模型中的应用揭示了该技术在软组织同时3D可视化中的潜力,骨头,和脉管系统。在同步加速器辐射设施(Elettra,的里雅斯特,意大利),所提出的实验装置可以很容易地转换成紧凑的实验室系统,包括传统的X射线管。
    Following the rapid, but independent, diffusion of x-ray spectral and phase-contrast systems, this work demonstrates the first combination of spectral and phase-contrast computed tomography (CT) obtained by using the edge-illumination technique and a CdTe small-pixel (62μm) spectral detector. A theoretical model is introduced, starting from a standard attenuation-based spectral decomposition and leading to spectral phase-contrast material decomposition. Each step of the model is followed by quantification of accuracy and sensitivity on experimental data of a test phantom containing different solutions with known concentrations. An example of a micro CT application (20μm voxel size) on an iodine-perfusedex vivomurine model is reported. The work demonstrates that spectral-phase contrast combines the advantages of spectral imaging, i.e. high-Zmaterial discrimination capability, and phase-contrast imaging, i.e. soft tissue sensitivity, yielding simultaneously mass density maps of water, calcium, and iodine with an accuracy of 1.1%, 3.5%, and 1.9% (root mean square errors), respectively. Results also show a 9-fold increase in the signal-to-noise ratio of the water channel when compared to standard spectral decomposition. The application to the murine model revealed the potential of the technique in the simultaneous 3D visualization of soft tissue, bone, and vasculature. While being implemented by using a broad spectrum (pink beam) at a synchrotron radiation facility (Elettra, Trieste, Italy), the proposed experimental setup can be readily translated to compact laboratory systems including conventional x-ray tubes.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    蚂蚁是积极产生生物孔隙和移动土壤颗粒的重要生物制造商。它们可能特别受到全球变暖的影响,因为它们是外温。然而,它们可以间接调节温度,通过改变它们的昼夜节律周期和它们的巢的结构(例如挖掘深巢或使用绝缘材料)。巢结构被认为是蚁群的扩展功能特征,因此对环境变化(例如温度升高)敏感。本工作旨在研究蚂蚁的巢结构作为一种功能性状及其对土壤生物扰动的影响。我们假设,当暴露于升高的表面温度时,蚂蚁会增加他们的挖掘活动,建造更深的巢穴并改变腔室的布局以保持其首选的温度和湿度,从而提高土壤孔隙度。我们允许17个年轻的LasiusNiger蚂蚁殖民地在暴露于三种表面温度(温和,n=5;中等,n=6;高,n=6)持续100天。我们测量了每周挖掘的土壤量,并在第7、14、28和88天对土壤柱进行了X射线扫描,以表征巢穴的三维结构(深度,形状,房间和隧道的体积)。然后我们收集菌落并在实验过程中测量它们的生长,以及工人的体型和体重。蚂蚁对表面温度起反应。暴露于中高温的菌落比暴露于温和温度的菌落挖出的巢更大,更深。在高温和中等温度下挖掘的巢穴具有相同的最大深度,但是房间位于前者更深的地方,进一步的特点是对一些上议院进行了改组。菌落在所有治疗中生长良好,虽然在温和的温度下较少。尽管地表温度不同,他们还是生产了正常大小的工人。总的来说,这些结果表明,暴露在较高温度下的蚂蚁生活在更深的房间里。这项研究表明,表面温度影响蚁巢建筑,确认其作为扩展表型的状态,并强调其随着时间的推移的灵活性,这反过来又对土壤孔隙度产生了影响。
    Ants are important bioturbators that actively produce biopores and move soil particles. They could be particularly affected by global warming as they are ectotherms. Nevertheless, they can indirectly regulate their temperature, through changes in their circadian cycles and the architecture of their nests (e.g. digging deep nests or using insulating materials). Nest architecture has been considered an expanded functional trait of ant colonies and thus sensitive to environmental changes such as increasing temperatures. This work aimed to study the nest architecture of ants as a functional trait and its effects on soil bioturbation. We hypothesized that, when exposed to increased surface temperatures, ants would increase their excavation activities, build deeper nests and alter the layout of chambers to maintain their preferred temperature and humidity, thus enhancing soil porosity. We allowed 17 young Lasius niger ant colonies to excavate nests in soil columns exposed to three surface temperatures (mild, n = 5; medium, n = 6; and high, n = 6) for 100 days. We measured the amount of soil excavated weekly and took X-ray scans of the soil column on Days 7, 14, 28, and 88 to characterize the three-dimensional structure of the nests (depth, shape, volume of chambers and tunnels). We then collected the colonies and measured their growth during the experiment, and the size and weight of workers. Ants reacted to surface temperature. Colonies exposed to medium and high temperatures excavated larger and deeper nests than those exposed to mild temperature. Nests excavated under high and medium temperatures had the same maximal depth, but chambers were located deeper in the former, which were further characterized by the refiling of some of the upper chambers. Colonies grew well in all treatments, although less under mild temperature. They produced normal-sized workers despite differences in surface temperature. Overall, these results suggest that ants exposed to higher temperatures live in deeper chambers. This study shows that surface temperature affects ant nest architecture, confirming its status as extended phenotype and highlighting its flexibility over time, which has in turn consequences on soil porosity.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    尽管很多研究都集中在通过基于激光的粉末床融合处理的AlSi10Mg上,材料微观变形机制尚不清楚。为了提高当前的认识,需要在微观结构尺度上对应变场进行3D测量,以补充基于表面的SEM观察。这项工作表明,X射线断层扫描与数字体积相关性相结合,可以使用热处理后的微观结构中包含的富Si颗粒作为标记来测量AlSi10Mg本体中的应变。该方法允许以35μm的空间分辨率测量大于0.5%的应变,因此可用于研究孔隙率分布或晶体学织构等因素对材料变形和损伤机理的影响。
    Although much research has focused on AlSi10Mg processed via laser-based powder bed fusion, the material deformation mechanisms at the microscale are still unclear. To improve the current understanding, 3D measurements of the strain field at the microstructural scale are needed to complement surface-based SEM observations. This work demonstrates that X-ray tomography combined with digital volume correlation can be used to measure the strain in the bulk of AlSi10Mg using the Si-rich particles contained in the heat-treated microstructure as markers. The method allows for measuring strains larger than 0.5 % with a spatial resolution of 35 μm and it can thus be used to study the impact of factors like porosity distribution or crystallographic texture on the material deformation and damage mechanisms.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

公众号