最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：Background: In order to satisfy the researchers’ strong requirement for a three-dimensional fine structure of the sample with high spatial resolution,the Nano-CT system based on the BL08U soft X-ray microspectroscopy station of Shanghai Synchrotron Radiation Facility(SSRF) has been developed,but sample drifted seriously while CT scanning.Purpose: The sample drift greatly reduces the accuracy and efficiency of CT experiment,so that an accurate online automatic calibration is necessary.Methods: Sample drift trajectory can be recorded in the rotation process by visible light microscope(VLM),and then the shift data of every angle can be obtained which can be used in calibration online.Results: The sample drift had been calibrated and limited below 1 m after the calibration algorithm,which meet the accuracy requirement of the CT experiments.Conclusions: Automatic calibration greatly improves the efficiency and accuracy of Nano-CT experiment.关键词：Nano-CT;Sample drift;Automatic calibration
- 13
- |
- 12
- |
- 0
发布时间：2021-03-05 - 摘要：Background: A new type of beam loss monitor(BLM) system is needed in the synchrotron radiation light source or FEL facility to monitor the real-time beam loss inside the small-gap insertion devices.Purpose: A BLM system was developed with optical fiber as the probe to meet the requirements of SSRF.Methods: The whole system consists of a 30-m long step-index fiber,photomultiplier tubes(PMT),a 10-bit 8-GS/s high-speed waveform digitizer and a PXI input-output controller.The software was developed under the Linux system based on Experimental Physics and Industrial Control System(EPICS).A new measurement and corresponding calculation method were designed to make the system work well with the multi-bunch operation mode in the storage ring of SSRF.Results: The BLM system worked well at SSRF.And the results of beam experiments showed that the system could detect beam loss properly even at the 1-mA low current case.Conclusions: This system could be used in the detection of beam loss dose and position.In the experiments the counts of light pulses can be used as a rough estimation of beam loss dose.The noise floor is about 3.56% of the total count in the 220-mA top-up user operation mode.关键词：Beam loss monitor;Fiber;Cerenkov radiation;EPICS
- 12
- |
- 12
- |
- 0
发布时间：2021-03-05 - 摘要：Background: RecJ,a highly conserved protein in archaea and bacterium,is a single-stranded DNA(ssDNA)-specific 5 to 3 exonuclease that plays an important role in homologous recombination,base excision repair(BER) and methyl directed mismatch repair(MMR).And RecJ could degrade single-stranded RNA(ssRNA) from 3 to 5 specially.Purpose: RecJ from pyrococcus furiosus was expressed,purified and crystallized.The aim is to get the structure of the protein,clarify the functions of RecJ in cells and to investigate its effect on the degradation of different nucleotide substrates(DNA/RNA).Methods: In order to get the crystal of RecJ,E.coli was chosed to express the protein.And the protein was purified by metal-chelating chromatography and anion exchange chromatography.The crystal was obtained by screening and the crystal with better diffraction was got by optimization.The data was collected from beamline BL17U1 at SSRF.Results and conclusions: The crystal of P.fu RecJ was got by screening,but the structure has not been achieved because of the low resolution of crystal.关键词：RecJ protein;Expression and purification;Crystal screen;X-ray diffraction
- 12
- |
- 11
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Studies of the radiation effects on the floating-gate flash memory have been mainly focused on functionality measurement.Purpose: According to the present situation,flash memory was irradiated and annealed by60Co γ rays,and the TID failure mechanism of the device was analyzed.Methods: The function parameters including DC and AC were measured using a large scale integrated circuit testing system.The range of radiation-sensitive parameters was extended using the Verigy 93000 instrument and the shmoo test.Results: The results showed that the maximum operating frequency was radiation-sensitive parameter which has a significant change in radiation and annealing.Conclusions: Under strong electric field,due to the accumulation of oxide trapped charge and interface trap charge,the performance of charge pump circuit was deteriorated and the function of device was failed.Annealing characteristics indicated that the oxide trapped charge accounts for a major role.关键词：Floating-gate flash memory;Maximum operating frequency;Charge pump
- 12
- |
- 13
- |
- 0
发布时间：2021-03-05 - 摘要：Background: The radioactivity levels of rare earth residues in Jiangsu province are not well known,and there are no explicit laws on their regulation.Purpose: By analyzing the radioactive nuclides in rare earth residues of Jiangsu province,we plan to propose some suggestions on volume reduction.Methods: HPGe γ spectrometry sourceless efficiency calibration method is playing an important role in the radioactive analysis because of its high accuracy and efficiency.It can be used without standard radioactive source and is easy to be measured on the spot.The reliability of method was verified by using IAEA reference materials.Results: The results show that in the rare earth residues the radioactive equilibrium of uranium and thorium decay series has been broken,and the radioactive levels in different samples have obvious difference.Conclusions: Based on the results,this paper investigates and analyses the radioactive residues of rare earth smelting and separation plants in Jiangsu Province,and puts forward some suggestions on volume reduction.关键词：Rare earth;Residue;Radioactive equilibrium;Gamma spectrometry;Sourceless efficiency calibration
- 11
- |
- 13
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Ozone will be produced when the accelerator runs.Because ozone can cause corrosive damage to metal,ventilation duct has to be set in the irradiation room to discharge ozone.Purpose: Photons go into the ventilation duct,and then produce additional radiation.To do the quantitative assessment of radiation field at the outlet of duct,the simulate calculation of radiation doses at the outlet has been done.Methods: The Monte Carlo code of MCNP can analog the electronic and photon transport,so that using MCNP can solve the problem.Results: The result shows that the location and the number of backscattered interface of duct significantly affect the dosage rate while the size of duct doesn’t.Increasing a backscatter interface can lower dosage rate attenuation about three orders of magnitude.The dosage rate under the target is two orders of magnitude than that in the corner.The setting project of duct is drawn and the ratio of length and depth has been optimized.The duct should be about 3-m long and 80-cm deep when the multi-tortuous duct is placed under the target,and U-shaped duct should be about 6-m long and 1-m deep when it is set at the corner of irradiation room.Conclusions: In order to reduce dosage rates and economic costs,the shape of duct and the location of duct are designed critically.And according to the actual situation,the project is flexible.关键词：Radiation field;Ozone;Ventilation duct;MCNP
- 12
- |
- 13
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Inertial Confinement Fusion(ICF) now is one of the fastest-growing major fields in the world,and the study mainly focuses on the measurement of ICF targets filled with deuterium and tritium gases,which is a major unresolved technical problem and seriously hamperes the development of target fabrication technology in China.Purpose: We use nuclear analytic techniques based on nuclear microprobe system to measure the parameters of ICF targets,including the structural elements’ content and distribution,the distribution of doped element and the distribution of density.Methods: Proton Induced X-ray Emission(PIXE) is utilized to measure the distribution of dopant element Ca in ICF targets doped with Ca or not.Rutherford Back Scattering(RBS) is utilized to measure the contents of C and O and the distributions in ICF targets.Scanning Transmission Ion Microscopy(STIM) is used to measure the distribution of density.Results: The PIXE results show that the distribution of dopant Calcium is not uniform,and the ring-enrichment region indicates that the capsule is already broken.The RBS detects the thickness of each layer and the content ratios of Carbon,Oxide and Hydrogen as well as their distributions.And the STIM results show that the distribution of density is not homogeneous,neither the energy loss.Conclusions: Ion beam analytic techniques including PIXE,RBS and STIM based on nuclear microprobe system have their advantage in the measurement of ICF target.It is non-destructive,and can give the elemental content and their distribution of multi-element in the order of several micrometer.关键词：Nuclear microprobe;Ion beam analysis;ICF target
- 15
- |
- 14
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Due to the effect of near-field artifacts,the clearity of reconstructed image obtained by coded aperture imaging was decreased.Purpose: In order to explore a way to eliminate the effect and to enhance the image quality,a Geant4 simulation was performed in this work.Methods: On the basis of the principles of near-field artifact generation and elimination,coded aperture imaging of a 300 keV gamma source was simulated by Geant4 at near-field conditions with a mosaicked MURA(19×19) mask by single-and double-mode measurements,respectively.Results: The near-field artifacts were apparent in the images obtained by single-mode measurement,while they were almost eliminated by double-mode measurement.Similar results showed up in the imaging experiments with a commercial gamma camera.Conclusions: The near-field artifacts would be inhibited or even eliminated by the double-mode measurement otherwise from the conventional single-mode measurement,resulting with an enhanced signal-to-noise ratio(SNR) of reconstructed images.关键词：Double-mode measurement;Coded aperture imaging;Near-field artifact;GEANT4
- 16
- |
- 14
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Buthus martensii Karsch Chlorotoxin(BmK CT) has been shown to inhibit the invasion ability of glioma cells by selectively restraining the Cl channel of glioma cells.Purpose: We aim to explore the effect and the mechanism of125I-BmK CT on the invasion ability of glioma.Methods: Transwell method was used to evaluate the invasion ability of glioma cells.The ELISA was used to evaluate the effect of125I-BmK CT on the secretion of MMP2.The Real-Time PCR and Western-blot were used to detect the effect of125I-BmK CT on the expression of MMP2 mRNA and protein.Results: Transwell indicated that both125I-BmK CT and BmK CT can inhibit the invasion ability of glioma cells,and125I-BmK CT was superior to BmK CT(P<0.05).ELISA indicated that the secretion of MMP2 protein can be inhibited by125I-BmK CT significantly(P<0.05).Real-Time PCR indicated that125I-BmK CT can not affect the synthesis of MMP2 in gene level(P>0.05).Western-blot indicated that 125I-BmK CT can inhibit the protein synthesis of MMP2(P<0.05).Conclusions:125I-BmK CT can inhibit the invasion ability of glioma cells,which may be related with the decreased secretion and synthesis of MMP2.关键词：125I-BmK CT;Marx metallopmteinase-2;Glioma
- 15
- |
- 14
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Polyvinyl alcohol(PVA) has been widely used in the industry of textile,however,its aqueous solution was difficult to be biodegraded under natural conditions.Purpose: In this study,the PVA in aqueous solution was degraded by electron beam irradiation.Methods: Radioactive ray from electron accelerator was used for degradation of PVA aqueous solution.The effects of different radiation dose and pH on the CODCr and BOD5 values of PVA aqueous solution were investigated.The precipitation generated from acidic irradiated PVA aqueous solution was used for infrared spectroscopy analysis.Results: CODCr values of neutral and alkaline PVA aqueous solution were not significantly changed in the radiation dose range of 0 30 kGy.Acidic PVA aqueous solution after 20 30 kGy dose irradiation produced precipitation obviously.The CODCr values were significantly reduced by 97% 98%.Infrared spectrum analysis showed that precipitation was cross-linked PVA.With radiation dose increasing,BOD5 values of different pH of PVA aqueous solution was gradually reduced,the acidic BOD5 values were minimal under the same radiation dose.The B/C values of neutral and alkaline PVA aqueous solution irradiated by the dose range of 0 30 kGy was no significantly changed.However,the B/C values of acidic PVA aqueous solution increased obviously after 20 30 kGy irradiation,and it increased 14 16 times.Conclusions: This study indicated that under the acidic circumstance,the CODCr values of PVA aqueous solution decreased significantly,PVA in aqueous solution was removed efficiently by electron beam irradiation,and the potential of biodegradation was also improved.关键词：Polyvinyl alcohol;Irradiation treatment;CODCr;BOD5;Precipitation product analysis;Treatment/degradation
- 11
- |
- 13
- |
- 0
发布时间：2021-03-05 - 摘要：Background: The power supply control system of Shanghai Deep Ultra-Violet Free Electron Laser(SDUV-FEL) test facility is an Ethernet-based distributed control system developed and integrated using the Experimental Physics and Industrial Control System(EPICS) toolkit.Purpose: The SDUV-FEL test facility has been integrated to test new FEL principles.Methods: The power supply control system provides control scheme for direct I/O controlled analog power supply,full digital-controlled power supply and Agilent commercial power supply with GPIB interface.Embedded I/O controller,runtime database and graphic operation interface are applied in this system.Results: The high performance of system demonstrated that the SASE and seeded FEL experiments were carried out in the past years.Conclusions: The power supply control system of the SDUV-FEL test facility has achieved long-term stable running,which is useful for future similar facility.关键词：Shanghai deep UV free electron laser;Magnet power supply;EPICS;Control system
- 12
- |
- 14
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Location nuclear imaging systems have been used in many fields,such as astronomical observation,radioactive source monitoring,nuclear development,biomedicine,etc.Purpose: It puts forward much higher requirements of monitoring and control of safety of nuclear facilities and radioactive sources.In this paper,a new portable nuclear imaging system is designed,which can be used in far field imaging.Methods: It uses high resolution detector which consists of LaBr3 crystal and H8500 position sensitive photomultiplier to meet the design requirements of high resolution.In order to acquire the higher radiation collection efficiency,we choose modified uniformly redundant arrays(MURA) as system collimator.It uses the maximum likelihood-expectation maximization(MLEM) algorithms in reconstruction procedure.Results: The test results show that the imaging system can image the far field radioactive source clearly.The field-of-view of our system can achieve the design goal: ±10° ±20°,and its resolution can be variable among 0.923° 2.038°.Conclusions: It can meet the design requirements of resolution and FOV very well.This radiation imaging system can achieve miniaturization and portability radiation imaging robot which is suited for the long-range control.关键词：Nuclear imaging;Collimator;MURA;Image reconstruction
- 50
- |
- 24
- |
- 0
发布时间：2021-03-05 - 摘要：Background: In recent years,X rays are widely used in various fields.With the rapid development of national economy,the demand of high quality,high reliability,and high stability miniature X-ray tube has grown rapidly.As an important core component of miniature X-ray tube,high voltage power supply has attracted wide attention.Purpose: To match miniature,the high voltage power supply should be small,lightweight,good quality,etc.Based on the basic performance requirements of existing micro-X-ray tube high voltage power supply,this paper designs an output from 0 to 30 kV adjustable miniature X-ray tube voltage DC power supply.Compared to half-bridge and full-bridge switching-mode power supply,its driving circuit is simple.With working on the linear condition,it has no switching noise.Methods: The main circuit makes use of DC power supply to provide the energy.The resonant Royer circuit supplies sine wave which drives to the high frequency transformer’s primary winding with resultant sine-like high voltage appearing across the secondary winding.Then,the voltage doubling rectifying circuit would achieve further boost.In the regulator circuit,a feedback control resonant transistor base current is adopted.In order to insulate air,a silicone rubber is used for high pressure part packaging,and the output voltage is measured by the dividing voltage below 5 kV.Results: The stability of circuit is better than 0.2%/6 h and the percent of the output ripple voltage is less than 0.3%.Keeping the output voltage constant,the output current can reach 57 A by changing the size of load resistor.This high voltage power supply based on resonant Royer can meet the requirement of miniature X-ray tube.Conclusions: The circuit can satisfy low noise,low ripple,low power and high voltage regulator power supply design.However,its efficiency is not high enough because of the linear condition.In the next design,to further reduce power consumption,we could improve the efficiency by controlling the current of resonant circuit.关键词：High voltage DC power;Resonant Royer;Voltage doubling rectifying circuit
- 15
- |
- 12
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Elastic scattering is induced by weakly unstable nuclei.Generally,a good angular resolution for angular distribution of elastic scattering is needed.The silicon strip detector is often used for this kind of experiment.Purpose: In order to use silicon strip detector to study the elastic scattering of weakly unbound nuclei,it is important to get the information of its position calibration.It is well known that the elastic scattering of stable nuclei has a good angular distribution and many experimental data have been obtained.Methods: So the scattering of stable nuclei can be used to calibrate the position information of silicon strip detector.In this experiment,the positions of silicon strip detectors are calibrated using 101 MeV and 59 MeV16O scattering on the197Au target.Results: The quasi-elastic peaks can be observed in the silicon strip detectors and the counts of quasi-elastic16O can be obtained.The solid angles of the silicon strip detectors are calibrated by using alpha source which has three alpha energy values.The angular distribution of quasi-elastic scattering of16O+197Au is obtained at these two energy values.Conclusions: The experimental data of angular distribution are reasonable and fit for the principle of angular distribution of elastic scattering.It is concluded that in the experiment these silicon strip detectors can accurately give the position information and can be used for the elastic scattering experiment.关键词：Quasi-elastic scattering;Angular distribution;Silicon strip detector
- 13
- |
- 13
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Squib valve is a key valve in the new generation nuclear power plant,which has not been localized and the research on the failure process of shear-cap is necessary.Purpose: This research aims to study the influence of material on the failure process of shear-cap in squib valve.Methods: The finite element method is used to simulate the shear-caps’ sheared process of different materials—Inconel 690,304 stainless steel and 321 stainless steel.Results: As a result,the failure time and the final speed of piston are shown at each impact speed.Conclusions: The shear-cap of Inconel 690 is hardest to shear.A method to get the critical impact speed in the open process of valve is proposed.It can be found that the residual kinetic energy of the piston has the common feature and is 25% of the initial kinetic energy.Piston’s final speed has a linear relationship to its initial speed for all three materials.关键词：Squib valve;Shear-cap;Material;Sheared;Failure;Critical speed
- 15
- |
- 12
- |
- 0
发布时间：2021-03-05
- Address：2019 Jialuo Road, Jiading, Shanghai, China Postal code：201800
- Tel：021-39194977 Email：LHB@sinap.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 沪ICP备05005479号-1
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
- Total Visits：675330 Visits Today：406
0