Experimental Study of the X-Ray Radiation Source at Approximately Constant Radiation Temperature

An X-ray radiation source with approximately constant radiation temperature is realized by irradiating golden hohlraum with a shaped laser pulse. A simple theoretical model based on power balance is used to design the shape of the drive laser pulse. Experiments are carried out on the Shenguang III prototype laser facility, and the experimentM results are presented for radiation sources with the flat-top lasting about 2.5 ns at two different peak temperatures of about 150 eV and 170 eV, respectively, including the the drive laser pulses and the time integrated possible improvements are discussed. time histories of the temperatures, the shapes of radiation spectra. The validity of the model and

X-Ray Radiation Sensing Properties of ZnS Thin Film:A Study on the Effect of Annealing

Chemically synthesized ZnS thin film is found to be a good x-ray radiation sensor. We report the effect of annealing on the x-ray radiation detection sensitivity of a ZnS thin film synthesized by a chemical bath deposition technique. The chemically synthesized ZnS films are annealed at 333, 363 and 393K for 1 h. Structural analyses show that the lattice defects in the films decrease with annealing. Further, the band gap is also found to decrease from 3.38 to 3.21 eV after annealing at 393K. Current-voltage characteristics of the films are studied under dark and x-ray irradiation conditions. Due to the decrease of lattice defects and band gap, the conductivity under dark conditions is found to increase from 2.06 × 10^-6 to 1.69 × 10^-5 S/em, while that under x-ray irradiation increases from 4.13 × 10^-5 to 5.28 ×10^-5 S/cm. On the other hand, the x-ray radiation detection sensitivity of the films is found to decrease with annealing. This decrease of detection sensitivity is attributed to the decrease of the band gap as well as some structural and surface morphological changes occurring after annealing.

Gamma and X-ray radiation compatibility of Ti–Ta–Hf–Zr alloys used for coronary stent applications

We have studied the gamma and X-ray radiation compatibility of Ti-based alloys such as Ti–37 Ta–26 Hf–13 Zr-24(wt%) [Alloy 1], Ti–40 Ta–22 Hf–11.7 Zr-26.3(wt%) [Alloy 2], Ti–45 Ta–18.4 Hf–10 Zr-26.6(wt%) [Alloy3], Ti–50 Ta–15 Hf–8 Zr-27(wt%) [Alloy 4], Ti–55 Ta–12 Hf–7 Zr-26(wt%) [Alloy 5], and Ti–60 Ta–10 Hf–5 Zr-25(wt%) [Alloy 6]. Gamma and X-ray radiation compatibility is studied by evaluating the mass attenuation coefficient,mean free path, HVL, TVL effective atomic number,effective electron density, exposure buildup factor, and relative dose. We have compared these parameters for studied alloys with that of arteries. The alloys Ti–55 Ta–12 Hf–7 Zr-26 and Ti–60 Ta–10 Hf–5 Zr-25 have added properties such as gamma/X-ray radiation compatibility,high elastic admissible strain, high mechanical strength,and excellent biocompatibility. Hence, we may suggest that, among Ti–Ta–Hf–Zr alloys, these alloys are best materials for coronary stent applications.

The effect of pre-low-dose X-ray radiation on tumor inhibition of HepG2 cells in tumor-bearing nude mice

Objective:The aim of this study was to discuss the effect of pre-low-dose X-ray radiation on P53,Bcl-2 and apoptosis of HepG2 cells in tumor-bearing nude mouse,and further explore the mechanism of low doses radiation.Methods:HepG2 cells were implanted subcutaneously into nude mice.14 days after the implanting,these mice were divided into 6 groups randomly,S group (sham-irradiation 0 cGy),D1 group (7.5 cGy,dosage rate=7.5 cGy/min),D2 group,(200 cGy,dosage rate=100 cGy/min),D1 + 2 h + D2 group,D1 + 6 h + D2 group and D1 + 12 h + D2 group.Tumor-bearing mice in each experimental group were executed at 24 h after the last irradiation.P53 and Bcl-2 were detected by immunohistochemical staining,the tumor tissues apoptosis were detected in site (Tunel).Results:Each combined exposure groups (D1 + 2 h + D2 group,D1 + 6 h + D2 group and D1 + 12 h + D2 group) compared with the D2 group,the percentages of positive P53 and Bcl-2 were decreased obviously,and the apoptotic indexs were increased (P < 0.01).Conclusion:Pre-low-dose radiation combined with the conventional radiation can increase the apoptosis of tumor tissues by decreasing the expression of P53 and Bcl-2,it can enhance the anti-tumor effect of conventional radiation,and it can have actual clinical significance on supporting radiotherapy.

Features of Malus Law in the Region of X-Ray Radiation

The light propagation through system a polarizer-analyzer is investigated on the basis of quantum conceptions about the nature of light. It is shown, that Malus law based on principles of classical electrodynamics not completely takes into account all effects which can occur at the light propagation through system a polarizer-analyzer. The phenomenon of possible change of frequency of light in particular drops out, for example in the region of X-ray radiation. The deduction of Malus law based on quantum principles is given. For comparison the differential effective section of interaction of a photon and electron with take into account of rotation of a plane of polarization of a photon in Compton’s effect is found.

Local low-dose X-ray radiation promotes homing of mesenchymal stem cells to the injured mouse spinal cord

BACKGROUND： Bone marrow-derived mesenchymal stem cells （BMSCs） are a potentially useful source for cell replacement therapy following spinal cord injury. However, the homing characteristics of BMSCs in vivo remain unclear. Low-dose radiation has been shown to promote homing of BMSCs to exposed sites. OBJECTIVE： To investigate the effects of low-dose local radiation to non-injured areas on the ability of human BMSCs to home to the injured mouse spinal cord, as well as recovery of spinal cord injury. DESIGN, TIME AND SE＇I-FING： A randomized, controlled, animal experiment was performed at the Central Laboratory, Second Affiliated Hospital of Soochow University between October 2007 and October 2008. MATERIALS： BMSCs were isolated from four adult, human donors. METHODS： Fifty adult, female, Balb/c mice were subjected to adjusted weight-drop impact resulting in complete paraplegia. Three days later, mice were randomly assigned to a radiation ＋ transplantation group （n = 23） and a transplantation group （n = 20）. In total, 2 x 106 carboxyfluorescein diacetate succinimidyl ester-labeled BMSCs were injected into each mouse via the caudal vein. Mice in the radiation ＋ transplantation group received 2.5 Gy local X-ray irradiation 2 hours before BMSCs injection. MAIN OUTCOME MEASURES： The homing of BMSCs to injured cord and irradiated skin after transplantation was observed by fluorescence microscope; the structure recovery of injured cord was assessed by magnetic resonance imaging. RESULTS： Compared with the transplantation group, at 24 hours after transplantation, the number of BMSCs was significantly increased in the injured area and the exposed site （P 〈 0.05）, and inflammation and edema were significantly alleviated in the injured cord in the radiation ＋ transplantation group. CONCLUSION： Local low-dose radiation has the potential to promote homing of BMSCs and recovery of spinal cord injury, although the radiated region was not injured area.

Establishment and study of a polarized X-ray radiation facility

With the advancement in X-ray astronomical detection technology,various celestial polarization detection projects have been initiated.To meet the calibration requirements of polarimeters on the ground,a polarized X-ray radiation facility was designed for this study.The design was based on the principle that X-rays incident at 45°on a crystal produce polarized X-rays,and a second crystal was used to measure the polarization of the X-rays produced by the facility after rotation.The effects of different diaphragm sizes on the degree of polarization were compared,and the facility produced X-rays with polarization degrees of up to 99.55±0.96%using LiF200 and LiF220 crystals.This result revealed that the polarization of incident X-rays is one of the factors affecting the diffraction efficiency of crystals.The replacement of different crystals can satisfy the calibration requirements of polarized X-ray detectors with more energy points in the energy range(4-10)keV.In the future,the facility should be placed in a vacuum environment to meet the calibration requirements at lower energies.

Effect of low-dose X-ray radiation on adaptive response in gastric cancer cell

Objective： We aimed to study the effect and mechanism of low-dose radiation （LDR） on adaptive response of gastric cancer cell. Methods： SGC7901 cells were cultured in vitro, and divided into 4 groups： control group （DO group）, low-dose radiation group （D1 group, 75 mGy）, high-dose radiation group （D2 group, 2 Gy）, low-dose plus high-dose radiation group （D1 ＋ D2 group, 75 mGy ＋ 2 Gy, the interval of low and high-close radiation being 8 h）. Cell inhibition rate was detected by cytometry and CCK8 method; the proportion of cell cycle at different times after irradiation was determined by using a flow cytometry. The ATM mRNA levels were detected by using quantitative real-time reverse transcription polymerase chain reaction （RT-PCR）. Results： There was no significant different between groups DO and D1, groups D2 and D1 ＋ D2 cell inhibition rate （P 〉 0.05）. There was a significant increase G2/M arrest in groups D2 and D1 ＋ D2 than groups DO and D1 after 6 h of radiation and did not recover at 48 h （P 〈 0.05）. The ATM mRNA expression of group D2 and D1 ＋ D2 increased highly than that of group DO and D1 （P 〈 0.05）. However, differences between group D2 and D1 ＋ D2, group DO and D1 were not statistical significant （P 〉 0.05）. Conclusion： LDR cannot induce adaptive response in SGC7901 cells in vitro, which may be associated the regulation of cell cycle, and its ATM mRNA expression cannot be affected by 75 mGy X-ray radiation.

The Transcriptional Response of Arabidopsis thaliana L. Genes AtKu70, AtRAD51 and AtRadl to X-Ray Radiation

The study of influence of the fractionated and acute ionizing radiation on plants revealed that it is able to induce genomic instability. The hypothesis that transcription rate of several evolutionary conserved DNA repair genes AtKu 70, AtRAD51 and AtRadl, which keeps genome stability in cells of model plant Arabidopsis thaliana, changes differently depending on dose and mode of ionizing radiation exposure had been tested. Gel electrophoresis-based reverse transcription polymerase chain reaction （RT-PCR） method was used for quantifying mRNA transcription levels. The data demonstrated that mode and dose of irradiation affect transcription rate of the genes AtKuTO, AtRAD51 and AtRadI. The fractionated and acute X-ray irradiation may result in adaptive response through the induction of key DNA double-strand break （DSB） repair genes AtKu70 and AtRAD51, as well as in genome instability through transcriptional activation of error-prone AtRadl-mediated DNA DSB repair combined with decreased expression of AtRAD51. In plants at doses within the range of 3-9 Gy, an adaptive influence is prevailed, but at doses of 12-21 Gy an error-prone repair of double-strand DNA damage is activated. Fractionation of dose has a significant effect on the transcription of the genes AtKuTO, AtRAD51 and AtRadl only at doses of 15 Gy and 21 Gy. Acute dose of 15 Gy activates error-prone AtRadl-mediated DSB repair and repressed both AtRAD51-dependent and AtKu70-dependent repair pathways, while fractionated irradiation at the same total dose induces more accurate homologous recombination and canonical non-homologous end joining of the DNA strands. In case of A. thaliana exposed to X-rays at dose 21 Gy, the situation is going reversed because of strong induction of the all three genome caretaker genes in leaves of acutely irradiated plants in contrast to the plants under fractionated exposure.

3-49 X-ray Radiation Induced Caspase-8 and Caspase-9 Activation in Human Colon Cancer Cells

Caspases as critical components in cell signaling pathways have been proved to be involved in events such asapoptosis, cell growth and differentiation. Two distinct apoptotic pathways related to the Caspase cascade have beenidentified; death receptor-induced apoptosis and mitochondrial stress-induced apoptosis. Death receptors triggerCaspase-8 and the mitochondria subsequently release apoptogenic factors (cytochrome c, Apaf-1, AIF), leading tothe activation of Caspase-9. The mitochondrial and death receptor apoptotic pathways are intimately connected[1].

3-51 Genistein Combined with X-ray Radiation Induces Oxidative Stress and Oxidative Damage in A549 Cells but Not in MRC-5 Cells

Selectively killing cancer without harming normal tissue is a fundamental challenge in cancer therapy. Elevatedoxidative stress and aberrant redox homeostasis are frequently observed in cancer cells compared with their normalcell counterparts[1]. A small shift toward an oxidizing condition in cells may lead to elevated proliferation andinduction of adaptive response. However, a high oxidizing condition often results in cell injury and cell death.Persistent high level of reactive oxygen species (ROS) in cancer cells usually elicits increased cell proliferation andadaptive responses that may contribute to tumorigenesis, metastasis, and treatment resistance. However, normalcells may still maintain redox homeostasis through adaptive responses. Therefore, regulating intracellular redoxstate may represent an ideal strategy to selectively sensitize cancer cells to oxidative stress-inducing therapy, suchas radiotherapy.

3-59 Radiosensitization to X-ray Radiation by Telomerase Inhibitor MST-312 in Human Hepatoma HepG2 cells

Telomerase inhibitor MST-312 is a new compound derived from epigallocatechin gallate (EGCG)[1]. Our resultsdemonstrated that 4 M MST-312 not only showed lower cytotoxicity, but also inhibited telomerase activity inHepG2 cells. Therefore, in our experiments, 4 M MST-312 was chosen to study radiosensitization and relatedmechanisms. -H2AX foci are considered as an indicator of DNA damages[2]. The immunofluorescence stainingresults showed the number of -H2AX foci in the pretreatment with MST-312 followed by 2 Gy X-ray irradiationgroup. However, as shown in Fig. 1, the formation of Rad51 foci in the combined treatment group was blockedoutside the nuclear of HepG2 cells, when compared with the irradiation alone group. JC-1 staining showed thatMST-312 pretreatment, followed by X-ray irradiation, caused increase of the green/red fluorescence intensity ratio(ΔΨm) compared with X-ray irradiation alone. Meanwhile, MST-312 pretreatment followed by X-ray irradiationelevated expression of p53 protein and decreased expression of caspase-3 as well as fraction of Bcl-2 / Bax.

Exploring the Accretion Disk Structure and X-ray Radiation of GX 17+2 Based on kHz QPOs and Cross-correlations

Applying the timing tools of kilohertz quasi-periodic oscillations(k Hz QPOs)and cross-correlations,we study the influence of the magnetosphere-disk relation on the X-ray radiation process of GX 17+2.First,as the spectral state track of X-ray emission evolves along the horizontal branch(HB),the magnetosphere-disk radii of the source derived by k Hz QPOs shrink from r~24 km to r~18 km,while its average X-ray intensities in≤10 ke V and in≥10 ke V show the opposite evolutional trends.Moreover,this branch has been detected with the anti-correlations between the low-/high-energy(e.g.,2–5 ke V/16–30 ke V)X-rays.We suggest that in HB there may exist an X-ray radiation transfer process at the disk radii near the neutron star(NS),i.e.,~5–10 km away from the surface,which probably originates from the interaction between the corona or jet with high-energy X-rays and accretion disk with low-energy X-rays.Second,as the source evolves along the normal branch(NB)and along the flaring branch(FB),their average X-ray intensities in all~2–30 ke V show the monotonously decreasing and monotonously increasing trends,respectively.In addition,these two branches are both dominated by the positive correlations between the low-and high-energy(e.g.,2–5 ke V/16–30 ke V)X-rays.Moreover,the evolution along NB is accompanied by the shrinking of the magnetosphere-disk radii from r~18 km to r~16 km.We ascribe these phenomena to that as the shrinking of the accretion disk radius,the piled up accretion matter around the NS surface may trigger the radiation that produces both the low-and high-energy X-rays simultaneously,and then form the branches of NB and FB.

A seven-crystal spectrometer for high-energy resolution X-ray spectroscopy at Shanghai Synchrotron Radiation Facility

A Johann-type X-ray spectrometer was successfully developed at the hard X-ray branch(in-vacuum undulator with a 24-mm periodic length)of the energy material beamline(E-line)at the Shanghai Synchrotron Radiation Facility(SSRF).This spectrometer was utilized to implement X-ray emission spectroscopy(XES),high-energy resolution fluorescence-detected X-ray absorption spectroscopy(HERFD-XAS),and resonant inelastic X-ray scattering.Seven spherically bent crystals were positioned on the respective vertical 500-mm-diameter Rowland circles,adopting an area detector to increase the solid angle to 1.75%of 4πsr,facilitating the study of low-concentrate systems under complex reaction conditions.Operated under the atmosphere pressure,the spectrometer covers the energy region from 3.5 to 18 keV,with the Bragg angle ranging from 73°to 86°during vertical scanning.It offers a promised energy resolution of sub-eV(XES)and super-eV(HERFD-XAS).Generally,these comprehensive core-level spectroscopy methods based on hard X-rays at the E-line with an extremely high photon flux can meet the crucial requirements of a green energy strategy.Moreover,they provide substantial support for scientific advances in fundamental research.

Two-dimensional particle-in-cell modeling of blow-off impulse by X-ray irradiation

Space objects such as spacecraft or missiles may be exposed to intense X-rays in outer space,leading to severe damage.The reinforcement of these objects to reduce the damage caused by X-ray irradiation is a significant concern.The blow-off impulse(BOI)is a crucial physical quantity for investigating material damage induced by X-ray irradiation.However,the accurate calculation of BOI is challenging,particularly for large deformations of materials with complex configurations.In this study,we develop a novel two-dimensional particle-in-cell code,Xablation2D,to calculate BOIs under far-field X-ray irradiation.This significantly reduces the dependence of the numerical simulation on the grid shape.The reliability of this code is verified by simulation results from open-source codes,and the calculated BOIs are consistent with the experimental and analytical results.

Insights into the hydrogen evolution reaction in vanadium redox flow batteries:A synchrotron radiation based X-ray imaging study

The parasitic hydrogen evolution reaction(HER)in the negative half-cell of vanadium redox flow batteries(VRFBs)causes severe efficiency losses.Thus,a deeper understanding of this process and the accompanying bubble formation is crucial.This benchmarking study locally analyzes the bubble distribution in thick,porous electrodes for the first time using deep learning-based image segmentation of synchrotron X-ray micro-tomograms.Each large three-dimensional data set was processed precisely in less than one minute while minimizing human errors and pointing out areas of increased HER activity in VRFBs.The study systematically varies the electrode potential and material,concluding that more negative electrode potentials of-200 m V vs.reversible hydrogen electrode(RHE)and lower cause more substantial bubble formation,resulting in bubble fractions of around 15%–20%in carbon felt electrodes.Contrarily,the bubble fractions stay only around 2%in an electrode combining carbon felt and carbon paper.The detected areas with high HER activity,such as the border subregion with more than 30%bubble fraction in carbon felt electrodes,the cutting edges,and preferential spots in the electrode bulk,are potential-independent and suggest that larger electrodes with a higher bulk-to-border ratio might reduce HER-related performance losses.The described combination of electrochemical measurements,local X-ray microtomography,AI-based segmentation,and 3D morphometric analysis is a powerful and novel approach for local bubble analysis in three-dimensional porous electrodes,providing an essential toolkit for a broad community working on bubble-generating electrochemical systems.

Comet assay and cytokinesis-blocked micronucleus test for monitoring the genotoxic effects of X-ray radiation in humans

Obejctive To assess the genotoxic effects of X ray radiation on human populations Methods The single cell gel electrophoresis (SCGE) and cytokinesis blocked micronucleus (CBMN) test were applied as biological dosimeters to detect DNA damage and abnormalities in human peripheral lymphocytes of subpopulation exposed to X ray radiation The subjects were divided into four groups: 12 radiation patients; 13 intervention radiation therapy doctors; 32 radiation diagnostians; 28 controls Results The average comet lengths of the four groups were 128 17±4 49?μm, 88 09±5 39?μm, 72 68±2 57?μm and 32 87±0 57?μm, respectively The difference in average comet length between any two groups was highly significant ( P <0 01) The average micronucleated cell (MNC) rates (‰) of the four groups were 12 33±0 85, 9 75±1 02, 8 48±0 66 and 3 18±0 36, respectively The difference of MNC rates of Group 1 vs 3, 1 vs 4, 2 vs 4 and 3 vs 4 was highly significant ( P <0 01), and the difference of Group 1 vs 2 was significant ( P <0 05), but there was no difference of MNC rate in Group 2 vs 3 ( P >0 05) Conclusions This study showed that both the comet assay and the CBMN test could be used to monitor populations exposed to X ray radiation, but the comet assay seems to be more sensitive than the CBMN test

Effects of leptin-modified human placenta-derived mesenchymal stem cells on angiogenic potential and peripheral inflammation of human umbilical vein endothelial cells(HUVECs) after X-ray radiation

Combined radiation-wound injury(CRWI) is characterized by blood vessel damage and pro-inflammatory cytokine deficiency. Studies have identified that the direct application of leptin plays a significant role in angiogenesis and inflammation. We established a sustained and stable leptin expression system to study the mechanism. A lentivirus method was employed to explore the angiogenic potential and peripheral inflammation of irradiated human umbilical vein endothelial cells(HUVECs). Leptin was transfected into human placenta-derived mesenchymal stem cells(HPMSCs) with lentiviral vectors. HUVECs were irradiated by X-ray at a single dose of 20 Gy. Transwell migration assay was performed to assess the migration of irradiated HUVECs. Based on the Transwell systems, co-culture systems of HPMSCs and irradiated HUVECs were established. Cell proliferation was measured by cell counting kit-8(CCK-8) assay. The secretion of pro-inflammatory cytokines(human granulocyte macrophage-colony stimulating factor(GM-CSF), interleukin(IL)-1α, IL-6, and IL-8) was detected by enzyme-linked immunosorbent assay(ELISA). The expression of pro-angiogenic factors(vascular endothelial growth factor(VEGF) and basic fibroblast growth factor(b FGF)) mRNA was detected by real-time quantitative polymerase chain reaction(RT-qPCR) assay. Relevant molecules of the nuclear factor-κB(NF-κB) and Janus kinase(JAK)/signal transducer and activator of transcription(STAT) signaling pathways were detected by western blot assay. Results showed that leptin-modified HPMSCs(HPMSCs/leptin) exhibited better cell proliferation, migration, and angiogenic potential(expressed more VEGF and bFGF). In both the single HPMSCs/leptin and the co-culture systems of HPMSCs/leptin and irradiated HUVECs, the increased secretion of pro-inflammatory cytokines(human GM-CSF, IL-1α, and IL-6) was associated with the interaction of the NF-κB and JAK/STAT signaling pathways. We conclude that HPMSCs/leptin could promote angiogenic potential and peripheral inflammation of HUVECs after X-ray radiation.

Vertical nanowires enhanced X-ray radiation damage of cells

Cell behavior is affected by nanostructured surface,but it remains unknown how ionizing radiation af-fects cells on nanostructured surface.This paper reports an experimental investigation of X-ray radiation induced damage of cells placed on an array of vertically aligned silicon nanowires.X-ray photoelectrons and secondary electrons produced from nanowire array are measured and compared to those from flat silicon substrate.The cell functions including morphology,viability,adhesion and proliferation have been examined and found to be drastically affected when cells are exposed to X-ray radiation,compared to those sitting on flat substrate and those only exposed to X-ray.The enhanced cell damage on nanowires upon X-ray exposure is attributed to nanowire enhanced production of photoelectrons including Auger electrons and secondary electrons,which have high escaping probability from sharp tips of nanowires.The escaped photoelectrons ionize water molecules and generate hydroxyl free radicals that can damage DNAs of cells.An inference of this work is that the contrast in scanning electron microscopy is useful in assessing the effects of nanomaterials for enhanced X-ray radiation therapy.

Assessing high-energy x-ray and proton irradiation effects on electrical properties of P-GaN and N-GaN thin films

The effects of ionizing and displacement irradiation of high-energy x-ray and 2-MeV proton on GaN thin films were investigated and compared in this study.The electrical properties of both P-GaN and N-GaN,separated from power devices,were gauged for fundamental analysis.It was found that the electrical properties of P-GaN were improved as a consequence of the disruption of the Mg-H bond induced by high-dose x-ray irradiation,as indicated by the Hall and circular transmission line model.Specifically,under a 100-Mrad(Si)x-ray dose,the specific contact resistance pc of P-GaN decreased by 30%,and the hole carrier concentration increased significantly.Additionally,the atom displacement damage effect of a 2-MeV proton of 1×10^(13)p/cm^(2)led to a significant degradation of the electrical properties of P-GaN,while those of N-GaN remained unchanged.P-GaN was found to be more sensitive to irradiation than N-GaN thin film.The effectiveness of x-ray irradiation in enhancing the electrical properties of P-GaN thin films was demonstrated in this study.