Characterization of Micro‐ and Nanoscale LuPO4:Pr3+,Nd3+ with Strong UV‐C Emission to Reduce X‐Ray Doses in Radiation Therapy

UV‐C emitting nanoscale scintillators can be used to sensitize cancer cells selectively against X‐rays during radiation therapy, due to the lethal DNA lesions caused by UV‐C photons. Unfortunately, nanoscale particles (NPs) show decreased UV‐C emission intensity. In this paper, the influence of different Nd³⁺ concentrations on the UV‐C emission of micro‐ and nanoscale LuPO₄:Pr³⁺ is investigated upon X‐ray irradiation and vacuum UV excitation (160 nm). Co‐doped LuPO₄ results in increased UV‐C emission independent of excitation source due to energy transfer from Nd³⁺ to Pr³⁺. The highest UV‐C emission intensity is observed for LuPO₄:Pr³⁺,Nd³⁺(1%,2.5%) upon X‐ray irradiation. Finally, LuPO₄ NPs co‐doped with different dopant concentrations are synthesized, and the biological efficacy of the combined approach (X‐rays and UV‐C) is assessed using the colony formation assay. Cell culture experiments confirm increased cell death compared to X‐rays alone due to the formation of UV‐specific DNA damages, supporting the feasibility of this approach.     

γ射线与N离子辐照类金刚石薄膜的机理研究

对类金刚石 (以下简称 DLC)薄膜受 γ射线与 N离子辐照的结果进行了比较 .通过 Raman光谱分析得出 :γ射线辐照造成薄膜中 SP3C— H和 SP2C— H键的减少及 SP3C— C键的增加 ,与此同时氢原子结合成氢分子 ,并从膜中释出 ,薄膜的类金刚石特征更加明显.当辐照剂量达1 0×104Gy时 ,SP3C—H键减少了约 5 0 % .N离子辐照使 DLC薄膜中 SP3C— C键、SP2 C—H键及 SP3C—H键的含量均变少 ,并伴随着氢分子的释出 ,直接导致 DLC薄膜的进一步石墨化,其对 SP3C—H及 SP2C— H键的破坏程度远大于γ射线 .两者在辐照机理上截然不同.The results of the diamond like carbon films(the following is called for short DLC film) irradiated by γ rays and N ion were reported. It showed that SP 3C—H and SP 2C—H bonds were decreased, and SP 3C—C bonds were increased by γ ray irradiation, and induced hydrogen recombination with H 2 molecules, and subsequently released from the surface of the films. When the γ ray irradiation dose reached 10×104Gy, the numbers of SP3C—H bonds were decreased by about 50%...     

X‐ray irradiation induces local rearrangement of silica particles in swollen rubber

X‐ray photon correlation spectroscopy (XPCS) of swollen rubber containing spherical silica nanoparticles is reported. It is shown that irradiation by intense X‐rays leads to the breakdown of cross‐links, thereby inducing the local rearrangement of silica nanoparticles. This rearrangement process depends on the cross‐link density and is characterized by a compressed exponential relaxation with aging behaviour, which resembles a common feature of complex fluids observed with XPCS.     

强脉冲X射线辐照Si-SiO2界面对C-V 和I-V特性曲线的影响

 利用强脉冲X射线对Si-SiO₂界面进行了辐照，测量了C-V曲线和I-V曲线。实验发现，经过强脉冲X射线对Si-SiO₂界面进行的辐照，使C-V曲线产生了正向漂移，这一点与低剂量率辐射结果不同；辐射后，感生I-V曲线产生畸变；特别地，从I-V曲线上还反映出强脉冲X射线辐照的总剂量效应造成电特性 参数明显退化，最后甚至失效。讨论了强脉冲X射线辐照对Si-SiO₂界面产生损伤的机理，并对实验结果进行了解释。     

模拟X射线热-力学效应电子束能谱的优化研究

实验室中主要采用电子束辐照来研究材料的热-力学响应规律,并以此为依据对材料抗核爆X射线的能力进行评估,此种评估方式忽略了电子束与X射线与物质相互作用中的差异,必然造成评估偏差。利用MCNP软件和约束最小二乘法,以1keV和3keV黑体X射线为优化对象,以电子束在介质中产生与X射线相同的能量沉积剖面为优化目的,对用于辐照铝、铜和钽三种材料的电子束能谱进行了优化计算,分别得到了它们的等效电子能谱。结果表明:等效电子能谱能够获得与相应的X射线一样的能量沉积剖面,可用作评估材料抗核爆X射线能力的依据;但等效电子谱与X射线和辐照材料均相关,应用中需依据辐照材料做出相应调整。     

Defect engineering by synchrotron radiation X‐rays in CeO2 nanocrystals

This work reports an unconventional defect engineering approach using synchrotron‐radiation‐based X‐rays on ceria nanocrystal catalysts of particle sizes 4.4–10.6 nm. The generation of a large number of oxygen‐vacancy defects (OVDs), and therefore an effective reduction of cations, has been found in CeO₂ catalytic materials bombarded by high‐intensity synchrotron X‐ray beams of beam size 1.5 mm × 0.5 mm, photon energies of 5.5–7.8 keV and photon fluxes up to 1.53 × 10¹² photons s^?1. The experimentally observed cation reduction was theoretically explained by a first‐principles formation‐energy calculation for oxygen vacancy defects. The results clearly indicate that OVD formation is mainly a result of X‐ray‐excited core holes that give rise to valence holes through electron down conversion in the material. Thermal annealing and subvalent Y‐doping were also employed to modulate the efficiency of oxygen escape, providing extra control on the X‐ray‐induced OVD generating process. Both the core‐hole‐dominated bond breaking and oxygen escape mechanisms play pivotal roles for efficient OVD formation. This X‐ray irradiation approach, as an alternative defect engineering method, can be applied to a wide variety of nanostructured materials for physical‐property modification.     

Beamline BL‐07 at Indus‐2: a facility for microfabrication research

The X‐ray lithography beamline on Indus‐2 is now operational, with two modes of operation. With a pair of X‐ray mirrors it is possible to tune the energy spectrum between 1 and 20 keV with a controlled spectral bandwidth. In its `no optics' mode, hard X‐rays up to 40 keV are available. Features and performance of the beamline are presented along with some example structures. Structures fabricated include honeycomb structures in PMMA using a stainless steel stencil mask and a compound refractive X‐ray lens using a polyimide–gold mask in SU‐8.     

X射线在影像增强器中散射特性的研究

Ｘ射线在影像增强器中的散射是影响Ｘ射线影像增强器输出图像对比度和分辨率的主要因素。首先用Ｍｏｎｔｅ Ｃｓｒｏｌｏ方法模拟了轫致辐射Ｘ射线与影像增强器的输入转换屏（ＣｓＩ：Ｎａ）的作用过程,给陋了透过转换屏的Ｘ射线的能谱。然后以无限大平面铁板作为增强器内电极和客壳的几何模型,以ＣｓＩ：Ｎａ的透过Ｘ射线能谱为铁板模型的入射能 ,分析了Ｘ射线在影像增强器中的背向散射特性。Ｘ射线管电压为２０～１２０ｋＣＶ     

Coherent X‐ray scattering beamline at port 9C of Pohang Light Source II

The coherent X‐ray scattering beamline at the 9C port of the upgraded Pohang Light Source (PLS‐II) at Pohang Accelerator Laboratory in Korea is introduced. This beamline provides X‐rays of 5–20 keV, and targets coherent X‐ray experiments such as coherent diffraction imaging and X‐ray photon correlation spectroscopy. The main parameters of the beamline are summarized, and some preliminary experimental results are described.     

氦气环境中湿样品软X射线显微成像研究

介绍了在国家同步辐射实验室软Ｘ射线显微术实验站上利用氦气进行软Ｘ射线显微成像研究的理论依据、实验装置以及实验结果和意义。     

斜入射脉冲X射线产生电流实验

 针对斜入射脉冲X射线与金属的几种可能相互作用机制,设计了实验布局,测量了斜入射X射线在金属靶上产生的脉冲电流,建立了相应的理论模型。结果显示,当X射线入射强度低于10⁵ W/cm²时,以光电效应为主,高于此值时,以热电效应为主导。这表明,X射线加载强度较弱时,电子表现出个体行为,而增大X射线入射强度,电子表现出弱关联集体行为。由此可以预测,超强X射线辐照下,金属表面将出现宏观尺度的电荷密度调制,在退激发过程中,这种调制状态可能以较高的效率辐射定向的微波电磁脉冲。     

软X射线条纹相机静态能量响应的绝对标定

软X光扫描相机是对软X光时间特性进行研究的主要诊断工具.利用同步辐射作为光源,采用美国NIST的标准,对它的静态能谱响应进行了绝对标定,给出了X光条纹相机在100—1000eV能区的绝对谱响应,不确定度小于23%.     

Simultaneous small‐ and wide‐angle scattering at high X‐ray energies

Combined small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) is a powerful technique for the study of materials at length scales ranging from atomic/molecular sizes (a few angstroms) to the mesoscopic regime (～1 nm to ～1 µm). A set‐up to apply this technique at high X‐ray energies (E > 50 keV) has been developed. Hard X‐rays permit the execution of at least three classes of investigations that are significantly more difficult to perform at standard X‐ray energies (8–20 keV): (i) in situ strain analysis revealing anisotropic strain behaviour both at the atomic (WAXS) as well as at the mesoscopic (SAXS) length scales, (ii) acquisition of WAXS patterns to very large q (>20 Å^?1) thus allowing atomic pair distribution function analysis (SAXS/PDF) of micro‐ and nano‐structured materials, and (iii) utilization of complex sample environments involving thick X‐ray windows and/or samples that can be penetrated only by high‐energy X‐rays. Using the reported set‐up a time resolution of approximately two seconds was demonstrated. It is planned to further improve this time resolution in the near future.     

Laser‐pump/X‐ray‐probe experiments with electrons ejected from a Cu(111) target: space‐charge acceleration

A comprehensive investigation of the emission characteristics for electrons induced by X‐rays of a few hundred eV at grazing‐incidence angles on an atomically clean Cu(111) sample during laser excitation is presented. Electron energy spectra due to intense infrared laser irradiation are investigated at the BESSY II slicing facility. Furthermore, the influence of the corresponding high degree of target excitation (high peak current of photoemission) on the properties of Auger and photoelectrons liberated by a probe X‐ray beam is investigated in time‐resolved pump and probe measurements. Strong electron energy shifts have been found and assigned to space‐charge acceleration. The variation of the shift with laser power and electron energy is investigated and discussed on the basis of experimental as well as new theoretical results.     

水窗波段附近激光等离子体X光辐射产生的途径

讨论了利用激光等离子体产生水窗波段Ｘ光辐射的可能途径。靶材，即原子序数的选取是决定产生这一波段辐射的基本因素，利用激光等离子体的平衡态和非平衡态特性都可在水窗波段产生亮度Ｘ光辐射，提出利用黑体辐射来实现水窗波段Ｘ光显微成像研究的方案。     

Three Dimensional Angular Distributions of X‐Rays in a 4 kJ Plasma Focus Device for Different Anode Tips Using TLD‐100 Dosimeters

Time and energy integrated measurements of the 3‐D angular distribution of X‐rays emission within the chamber of a 4 kJ Mather‐type plasma focus is investigated employing four different anode shapes and using nitrogen as the filling gas by the TLD‐100 thermoluminescence dosimeters. The distributions of X‐ray radiation in the energy range of 5 keV to several hundred keV were bimodal for all of the anode tips, peaked approximately at ±15°. The intensity of X‐rays decreased abruptly along the central axis of the device where the quasi cylindrical plasma pinch was formed. High intensity of X‐ray was observed in the case of a tapered ?at‐end anode, whereas less was obtained with the cylindrical hollow‐end anode. The maximum nitrogen X‐rays were for the tapered flat‐end anode at 4.5 mbar and 13 kV. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

电子束和X射线双曝光制作大高宽比高分辨率的X射线波带片

介绍了利用电子束和 X射线束双曝光技术制作大高宽比高分辨率的 X射线聚焦或色散元件的新方法 (波长范围为 1～ 5 nm )。所制做的厚度为 10μm的 Au波带片具有 30个波带 ,最外环的宽度为 0 .5μm。实验表明 :对 8ke V的X射线来说 ,波带片的衬度大于 10 ,分辨率为 0 .5 5μm,焦距为 2 1.3cm。     

Approaches to solid sample preparation based on analytical depth for reliable X‐ray fluorescence analysis

In this paper, we discuss approaches to prepare solid samples for X‐ray fluorescence spectrometry (XRF). Although XRF can be used to analyze major and minor elements in various solid samples including powders and grains without dissolution techniques, to obtain reliable XRF results, the prepared sample must meet certain criteria related to homogeneity, particle size, flatness, and thickness. The conditions are defined by the analytical depth of fluorescent X‐rays from analytes, and the analytical depth can be estimated from the X‐ray absorption related to the energy of each X‐ray and the composition and density of the sample. For example, when the sample flatness and particle size are less than the analytical depth and the sample possesses homogeneity within a depth less than the analytical depth, the XRF results are representative of the entire sample. Furthermore, an appropriate sample thickness that is larger than the analytical depth or constant can prevent changes in fluorescent X‐ray intensity with variations in sample thickness. To obtain accurate and reproducible measurements, inhomogeneous solid samples must be pulverized, homogenized, and prepared as loose powder, powder pellets, or glass beads. This paper explains the approaches used to prepare solid samples for XRF analysis based on the analytical depths of fluorescent X‐rays. Copyright © 2016 John Wiley & Sons, Ltd.     

Fluorescence imaging of reactive oxygen species by confocal laser scanning microscopy for track analysis of synchrotron X‐ray photoelectric nanoradiator dose: X‐ray pump–optical probe

Bursts of emissions of low‐energy electrons, including interatomic Coulomb decay electrons and Auger electrons (0–1000 eV), as well as X‐ray fluorescence produced by irradiation of large‐Z element nanoparticles by either X‐ray photons or high‐energy ion beams, is referred to as the nanoradiator effect. In therapeutic applications, this effect can damage pathological tissues that selectively take up the nanoparticles. Herein, a new nanoradiator dosimetry method is presented that uses probes for reactive oxygen species (ROS) incorporated into three‐dimensional gels, on which macrophages containing iron oxide nanoparticles (IONs) are attached. This method, together with site‐specific irradiation of the intracellular nanoparticles from a microbeam of polychromatic synchrotron X‐rays (5–14 keV), measures the range and distribution of OH radicals produced by X‐ray emission or superoxide anions () produced by low‐energy electrons. The measurements are based on confocal laser scanning of the fluorescence of the hydroxyl radical probe 2‐[6‐(4′‐amino)phenoxy‐3H‐xanthen‐3‐on‐9‐yl] benzoic acid (APF) or the superoxide probe hydroethidine‐dihydroethidium (DHE) that was oxidized by each ROS, enabling tracking of the radiation dose emitted by the nanoradiator. In the range 70 µm below the irradiated cell, radicals derived mostly from either incident X‐ray or X‐ray fluorescence of ION nanoradiators are distributed along the line of depth direction in ROS gel. In contrast, derived from secondary electron or low‐energy electron emission by ION nanoradiators are scattered over the ROS gel. ROS fluorescence due to the ION nanoradiators was observed continuously to a depth of 1.5 mm for both oxidized APF and oxidized DHE with relatively large intensity compared with the fluorescence caused by the ROS produced solely by incident primary X‐rays, which was limited to a depth of 600 µm, suggesting dose enhancement as well as more penetration by nanoradiators. In conclusion, the combined use of a synchrotron X‐ray microbeam‐irradiated three‐dimensional ROS gel and confocal laser scanning fluorescence microscopy provides a simple dosimetry method for track analysis of X‐ray photoelectric nanoradiator radiation, suggesting extensive cellular damage with dose‐enhancement beyond a single cell containing IONs.     

Mechanical stress X‐ray emission from crystal sugar

We report a new phenomenon of generating X‐rays by fracturing a well‐known material, crystal sugar, in a vacuum. The generated X‐rays had a maximum energy of 250 keV and peak energy of 5 keV. The X‐ray pulses continued for 4 × 10^?3 s. Copyright © 2014 John Wiley & Sons, Ltd.