On the production of X-rays by low energy ion beams

Although electron beams with energies of a few keV can excite fluorescent X-ray production from solids, ion beams of comparable energy cannot do so. The reason for this situation is that it is the velocity of the incident particle, rather than its energy, which determines whether an ionization event can be generated.     

The application of X-ray microscopy in materials science

X-ray microscopy is a form of high resolution radiography that uses low-energy X-rays (≤10 keV) to enhance the contrast between light elements such as hydrogen, carbon, nitrogen and oxygen. As performed on compact laboratory equipment the technique can achieve spatial resolutions of roughly 1 μm in virtually any material given that the specimen is sufficiently thin (typically 0·2–2 mm) to be adequately transparent to low-energy X-rays. Notwithstanding that the technique has lately found favour in biomedical radiology, its considerable potential in other fields, notably the materials sciences, remains largely unexploited. The scope and potential of laboratory X-ray microscopy in the materials sciences is demonstrated here by its application to ceramics, elastomers, coal-chars and reinforced composites. In all cases the technique provided valuable microstructural characterization often unobtainable by any other non-destructive method. These examples demonstrate that laboratory X-ray microscopy offers much to the materials sciences and deserves a wider application than is current.     

Visualizing soft tissue in the mammalian cochlea with coherent hard X-rays

This paper concerns an important aspect of current developments in medical and biological imaging: the possibility for imaging soft tissue at relatively high resolution in the micrometer range or better, without tedious and/or entirely destructive sample preparation. Structures with low absorption contrast have been visualized using in-line phase contrast imaging. The experiments have been performed at the Advanced Photon Source, a third generation source of synchrotron radiation. The source provides highly coherent X-ray radiation with high photon flux (>10(14) photons/s) at high photon energies (5-70 keV). Thick gerbil cochlear slices have been imaged and were compared with those obtained by light microscopy. Furthermore, intact gerbil cochleae have been imaged to identify the soft tissue structures involved in the hearing process. The present experimental approach was essential for visualizing the inner ear structures involved in the hearing process in an intact cochlea.     

Microradiography as a tool to detect heavy metal uptake in plants for phytoremediation applications

In this paper, an application of contact microradiography with soft X-rays for detecting the uptake site of heavy metal in the whole plant leaves is investigated. The X-ray source is a laser-plasma one based on an Nd:glass laser. The soft X-ray radiation emitted from the plasma laser targets of magnesium, iron, and copper can be strongly absorbed in the leaves' regions rich in iron, magnesium, and copper. This absorbance could point to structures in the leaves where these heavy elements are found. In this work, leaves treated with copper sulfate diluted in water at 1, 2, and 5% were imaged by using a copper target, in order to evaluate differences with untreated control leaves. Our results showed that this methodology highlighted the presence of copper in the treated leaves. This new methodology should detect heavy element pollutants inside plants and it should also be a useful analytic tool in phytoremediation studies.     

High-resolution X-ray refraction imaging of rat lung and histological correlations

This study was performed to observe microstructures of the rat lung, using a synchrotron radiation beam and to compare findings with histological observations. X-ray refraction images from ex-vivo ventilating rat lung were obtained with an 8 KeV monochromatic beam and 20-mum thick CsI(Tl) scintillation crystal. The visual image was magnified using a 20x microscope objective and captured using an analog CCD camera. Obtained images were compared with conventional light microscopic findings from the same tissue. Pulmonary microstructures, including alveolar ducts, alveolar sacs, alveoli, alveolar walls, and perialveolar capillary networks were clearly identified with spatial resolution of as much as 1.2 mum and had good correlation with conventional light microscopic findings. The shape of alveoli appeared more round in SR images than in the light microscopic images. The results suggest that X-ray microscopy study of the lung using synchrotron radiation demonstrates the potential for clinically relevant microstructure of lung tissue without sectioning and fixation.     

软X射线接触式显微术研究

按照生物样品各分辨单元具有多种透过率的特点,设计了一个多衬度的台阶状蛋白质模型,根据曝光量与衬度,信噪比,抗蚀膜性能的关系,确定了曝光量。同时模拟样品模型各台阶的真实成像条件,测量了各台阶所对应的抗蚀膜显影速率曲线,对显影条件作了定量分析。将曝光量,显影条件,与分辨率紧密结合起来,找到了一种较好的实验方法。     

软 X 射线接触式显微术抗蚀膜显影条件分析

按照生物样品各分辨单元具有多种透过率的特点,设计了一个多衬度的台阶状蛋白质模型,模拟各台阶的真实成像条件,测量了各台阶所对应的抗蚀膜显影速率曲线,对显影条件作了定量分析,并将显影条件与分辨率紧密结合起来,找到了一种较好的定量确定显影条件的方法。