CR摄影技术在皮下埋植剂取出术中的应用价值

目的探讨CR摄影技术在皮下埋植剂取出术中的应用价值。方法在对584例育龄妇女进行左炔诺孕酮硅胶棒皮下埋植避孕剂(简称皮下埋植剂)的取出术中,有12例在取出时,出现取出困难。取出前常规消毒,在受术者的上臂内缘皮肤触摸,能触及皮下埋植剂,然后在上臂内侧缘肘关节上方3.0cm处皮肤上做一切口,进行皮下埋植剂的取出术,取出1根后,另1根反复寻找仍不见皮下埋植剂,然后拍上臂正、侧位CR片。结果在受术者上臂内侧缘肘关节上方3.0cm肌层深0.6cm处可见一纵形长约4.5cm直径0.3cm的管状阴影,长度直径均符合皮下埋植剂。结论 CR摄影技术能准确定位皮下埋植剂,尤其是侧位片定位更为准确。使手术医生能顺利取出皮下埋植剂,减少受术者痛苦,因此有推广价值。     

Measurement of w-InN/h-BN Heterojunction Band Offsets by X-Ray Photoemission Spectroscopy

X-ray photoelectron spectroscopy has been used to measure the valence band offset (VBO) of the w-InN/h-BN heterojunction. We find that it is a type-II heterojunction with the VBO being −0.30 ± 0.09 eV and the corresponding conduction band offset (CBO) being 4.99 ± 0.09 eV. The accurate determination of VBO and CBO is important for designing the w-InN/h-BN-based electronic devices.     

康普顿散射对X射线透射谱的影响

采用一定组分的材料对X射线进行辐射屏蔽,可以吸收大部分的低能光子,减少X射线对电子系统的辐射损伤。但通过研究发现,由于康普顿散射的影响,在一定条件下,透射谱中的低能光子数不但没有减少反而大于入射谱,这对于电子元器件的辐射防护是不利的。通过改变入射源光子能谱、探测器位置、屏蔽材料类型以及屏蔽材料厚度等参量,采用蒙特卡罗方法计算并分析了散射光子对X射线透射谱的影响,得到了康普顿散射光子对X射线透射谱的影响规律,并提出了降低散射光子影响的几种措施。     

A simple method for the measurement of organic iodine in wastewater and surface water

Total adsorbable organic iodine (TAOI) has been used as a surrogate parameter for X-ray contrast media in municipal wastewater. Available methods require specialized equipment for pyrolyzing these compounds to convert the covalently bound iodine into iodide, which is then measured by ion chromatography. In this study we describe a simple method for liberating iodide from these compounds with Cu(II) and hydrogen peroxide. Concentrations of TAOI were measured in wastewater effluent, surface waters that were expected to be impacted by wastewater, and unimpacted surface waters. TAOI concentrations ranged between 1.9 and 16.3 microg/L I in wastewater with a median of 6.5 microg/L I. The lowest TAOI concentrations consistently were detected in a wastewater treatment plant that apparently had few hospitals within its collection area. In comparison, TAOI concentrations in surface water that was unimpacted by sewage were between 0.3 and 3.5 microg/L I. TAOI concentrations in surface waters that were impacted by sewage were consistent with the expected conservative behavior of TAOI.     

Disorders and oxygen vacancies in p-type Sn2B2O7 (B = Nb,Ta): Role of the B-site element

Sn₂Nb_2−xTa_xO₇ (x = 0.0–2.0) with pyrochlore structure is a promising material for p-type oxide semiconductors. A systematic study of its Nb/Ta ratio indicated that the hole–generation efficiency of the Nb end (Sn₂Nb₂O₇) was an order of magnitude lower than that of the Ta end (Sn₂Ta₂O₇). Although this occurs due to differences in oxygen-vacancy formation, the origins of the hole–generation efficiencies remain unclear due to limited information on local and global crystal-structure disorders in pyrochlore Sn₂Nb₂O₇ and Sn₂Ta₂O₇. In this study, the crystal structures of Sn₂B₂O₇ (B = Nb, Ta), composed of BO₆ octahedra and Sn₄O tetrahedra, were investigated using X-ray absorption spectroscopy and X-ray diffraction. A detailed investigation of the local and global crystal structures indicated a larger amount of disorder in the Sn₄O tetrahedra in Sn₂Nb₂O₇ compared to Sn₂Ta₂O₇; disorder in the BO₆ octahedra occurred only in Sn₂Ta₂O₇. This study indicates that an appropriate selection of the B-site element is vital for suppressing defect and disorder formation in Sn₄O tetrahedra and subsequently improving the hole–carrier–generation efficiency.     

Deep learning-based hybrid reconstruction algorithm for fibre instance segmentation from 3D x-ray tomographic images

3D x-ray tomography is a powerful scanning technique used for generating images of complex fibre structures. A novel machine-learning algorithm to identify and separate individual fibres using 3D images is proposed in this article. The developed four-step hybrid 3D fibre segmentation algorithm involves deep-learning aided semantic segmentation that slices 3D images to create 2D images for fibre extraction, elliptical contour estimation combined with the marker-controlled watershed algorithm for separating fibres from the background area, identifying individual fibres through 3D reconstruction, and, lastly, the 3D object refining approach based on outlier object detection and replacement. The proposed methodology is implemented on a real-time sample of nylon fibre bundle under compression and its 3D x-ray image volume to validate the performance. The results show its superior performance compared to off-the-shelf image processing algorithms in terms of precision, that is, with a validation accuracy greater than 90%, and efficiency, that is, preventing the need for a huge data set and reducing the complexity.     

Highly-doped YAG:Sm3+ transparent ceramics: Effect of Sm3+ ions concentration

YAG:Sm³⁺ (3–15 at.%) transparent ceramics, a promising cladding material for suppressors of parasitic oscillations at 1064 nm of YAG:Nd³⁺ lasers, have been prepared by solid-state reactive sintering at 1725 °C. The effect of samarium ions concentration on the microstructure and optical properties of YAG:Sm³⁺ sintered ceramics was studied for the first time. The solubility limit of samarium ions in the garnet matrix was found to lie within the range of 9–11 at.%. The spectroscopic characterization of YAG:Sm³⁺ (3–15 at.%) ceramic samples showed that the absorption coefficients corresponding to Sm³⁺ ions transitions increased linearly with increasing Sm³⁺ doping. Also, the increase in the concentration of Sm³⁺ ions contributes to the increase in the intensities of the satellites, leading to the broadening of the main spectral lines and implicitly to the increase of the absorption coefficient around 1064 nm. It was shown that YAG:Sm³⁺ ceramics doped with 9 at.% Sm³⁺ ions possess optical losses of 0.07 cm^?1 at 808 nm and an optical absorption coefficient of 4.45 cm^?1 at 1064 nm. The concentration dependence of the ⁴G_5/2 level decay confirmed that the luminescence extinction is due to the energy transfer between the Sm³⁺ ions through cross-relaxation processes. All these results show that highly-doped YAG:Sm³⁺ (9 at.%) ceramics could be the best candidate for parasitic oscillation suppression in high-power YAG:Nd³⁺ lasers at 1064 nm.     

The accuracy of predicting carcass composition of three different pig genetic lines by dual-energy X-ray absorptiometry

The accuracy of dual energy X-ray absorptiometry (DXA) for predicting carcass composition was evaluated by applying this technology to 95 half-carcasses of gilts from three genetic lines of widely varying composition. The DXA measurements of total weight, fat and lean masses and bone mineral content were used to predict the dissected lean, fat, bone and weight of the major primal cuts and the overall carcass. The study showed that it is not necessary to correct, or rather adjust, the prediction equations between genetic lines, given the small decrease in the prediction error (less than 1.43%). Except for the prediction for loin bone weight, the results showed that incorporating more than one of the predictive variables derived from DXA or from direct carcass measurements into the regression models was not justified in terms of prediction accuracy. The best predictions were those for half-carcass weight and primal cut weights (R² > 0.95). The prediction of dissected lean ranked second in accuracy (R² > 0.85), with the exception of the belly. The equations using DXA measurements provide good estimation (R² > 0.70) of the weight of fat in the carcass and primal cuts. However, DXA showed moderate accuracy (R² < 0.66) in predicting bone weight, although greater accuracy was attained for loin bone weight using a two-variable prediction model.     

Structural and Dielectric Properties of Ca Doped Barium Iron Niobate

Ceramic materials with high dielectric constant are being used in many electric and electro-optics applications. Ca substituted barium iron niobate with general formula (Ba_1-xCa_x) (Fe_0.5Nb_0.5)O₃ with x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were prepared by conventional solid state reaction method. Structural properties were investigated using X-ray diffraction and scanning electron microscope. Two types of phases were observed for 0.4 ≤ x ≤ 08. Dielectric constant and loss tangent were measured using impedance analyzer in the frequency range of 20 Hz–1 MHz at room temperature. Dielectric constant and loss tangent were found to decrease with increasing the frequency. A relatively good combination of dielectric constant and loss tangent was obtained for x = 0.2 (?_r = 1441 and tan δ = 0.19) at 10 KHz.     

激光等离子体X射线特征谱轮廓诊断

开展了利用X射线特征谱轮廓诊断激光等离子体状态参数的研究。在"神光II"激光装置上,将0.35μm频谱激光束聚焦于真空室内固体氯(Cl)元素靶上产生激光氯等离子体,利用高分辨X射线椭圆弯晶谱仪获取高能谱分辨激光氯等离子体辐射的X射线精细结构能谱。用类氢(1s-3p)和类氦(1s2-1s3p)氯离子能级跃迁光谱线的光强度比率计算了激光等离子体的电子温度;然后在假定光性为薄的情况下,利用X射线谱线Lyman-线形轮廓的Stark效应所产生的谱线展宽测量了等离子体的电子密度。实验获得的激光等离子体日冕区内体平均电子温度约为450eV,电子密度约为7.5×1022 cm-3。文中还简单分析了能谱线的半高全宽度(FWHM)值以及诊断过程引入的诊断误差,初步预估诊断误差可控制在25%以内。该项工作为X射线特征谱轮廓法进一步应用于激光聚变靶丸压缩度精度测量等工作提供了参考。