最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：Background: Identifying the natures of the active sites in the catalysts is one of the key issues for the catalytic mechanism research.However,no accurate conclusions regarding to the nature of the electrocatalytic site that active in oxygen reduction reaction（ORR） can be extracted based merely on ex situ data of the dry material.Purpose: A new kind of in situ experimental setup based on BL15U1 in Shanghai Synchrotron Radiation Facility（SSRF） is designed to study the catalytic mechanism deeply by in situ characterization which is expected to be the most direct and necessary method.Methods: The in situ X-ray Diffraction（XRD） and Fluorescent X-ray Absorption Near Edge Structure（XANES） measurements were performed for the cathode catalyst（polypyrrole modified carbon supported cobalt hydroxide） of DBFC on BL15U1 in SSRF.Results: A new phase was formed during DBFC discharging,and the valence state varieties of Co atoms in cathode were recorded.Conclusions: Part of the Co2+ transformation to Co3+to form Co2+/Co3+balance during the catalytic reaction,resulting in the formation of a new chemical phase.It is confirmed that,by the preliminary analysis,this setup can provide real time evidence which can be used to research the ORR catalytic mechanism of the direct borohydride fuel cell cathode catalyst.关键词：In situ experimental setup;Direct borohydride fuel cell;Mechanism for oxygen reduction reaction
- 16
- |
- 178
- |
- 0
发布时间：2021-06-03 - 摘要：Background: ZnO-based diluted magnetic semiconductors（DMSs） have attracted much attention for their potential applications in spintronics,which utilizes both the spin degree of freedom and electronic charge.After Dietl et al.theoretically predicted that ZnO doped with 5 at% Mn might exhibit room temperature ferromagnetism,most studies were focused on this system.The other transition metal such as Fe doped ZnO DMSs were rarely studied,especially,Fe and N codoped ZnO system.The thermal oxidation method,a very simple method,was used to prepare the ZnO:（Fe,N） films.First,Zn3N2: Fe films were grown by radio frequency（RF） reactive magnetron sputtering on quartz substrates and then annealed in oxygen atmosphere at different temperatures for 2 h.Purpose: This paper attempted to study annealing behavior and structural evolvement of Zn3N2:Fe at the different annealing temperature.Methods: Rutherford backscattering spectrometry（RBS） was a very powerful tool to study the growth of thin film.Therefore in this paper RBS combining with X-ray diffraction（XRD） was used to study the preparation of the ZnO:（Fe,N） films.Results: The results showed that the as-grown sample was Zn3N2:Fe film.After annealed at 300oC,Zn3N2:Fe in the surface had transformed to ZnO:（Fe,N） and the film under the surface was not oxidated.After annealed above 400oC,the Zn3N2:Fe film had entirely transformed to the polycrystalline ZnO:（Fe,N） film.Annealed at 500oC,the film started to diffuse into the substrate and at 600oC–700oC,the diffusion was very obvious.Conclusions: RBS combining with XRD can effectively study the preparation of the ZnO:（Fe,N） films.Within the range of the sensitivity,no precipitates such as Fe cluster or Fe3O4,Fe2O3 and FeO were observed by XRD.From SQUID,the maximum of the saturation magnetic moment（Ms） at room temperature appeared at 500oC.
- 12
- |
- 188
- |
- 1
发布时间：2021-06-03 - 摘要：Background: Digital nuclear signal filter shape is of great importance to the energy resolution and the counting rate in nuclear spectrometer system.Purpose: This paper attempts to achieve transfer function method and the synthesis forming filter shape based on LabVIEW.Methods: The digital nuclear signal which comes from the high speed ADC was formed a certain curvature of the concave and convex shaper in synthesis forming method,simply modify the forming parameters,the different shapes（trapezoid,triangle and gauss） were achieved by this method.Results: Finally,to validate the feasibility and practicability of the filtering methods,with the use of the modification of forming parameters on LabVIEW platform and the call of program in MATLAB,the transfer function and the synthesis forming method were used to complete filter shape.Conclusions: Based on the results,the filtering method can be used to provide technical support for the choices of filter shape schemes and parameters.关键词：Digital nuclear signal;LabVIEW;Filter shape
- 13
- |
- 294
- |
- 8
发布时间：2021-06-03 - 摘要：Background: Accurate and quantitative measurement of plasma radiation is a key issue to Tokamak,toroidal magnetic confinement device.The radiations from Tokamak cover large energy range.Driven by the determination of the obtaining of hard X-ray spectra,a new system based on a high performance CdTe detector was built up in EAST Tokamak,the first non-circle cross-section in the world.Purpose: Introduces the device of hard X-ray diagnosis system in the EAST Tokamak on the Port A.The system can measure the plasma hard X-ray（20–200 keV） spectra under different discharge conditions,including Ohmical shot and Lower Hybrid Current Drive（LHCD） shot.The research of high speed electron which produced by LHCD is also the aim of the new system.Methods: A high performance CdTe detector was using in EAST Tokamak to measure the hard X-ray（20–200 keV） spectra.Results: The results show that the new system based on a high performance CdTe can meet the requirements for measuring the EAST Tokamk.Conclusions: A preliminary experimental result showed that the system can meet the requirements for measuring the X-ray bremsstrahlung of plasma in the energy range from 20 to 200 keV.Calibration result and typical measurement result on EAST are present in this paper.关键词：Tokamak;Hard X-ray;LHCD;CdTe detector
- 18
- |
- 172
- |
- 8
发布时间：2021-06-03 - 摘要：Background: The interest on magnesium borate TL materials has arisen because of their dosimetric properties,such as good tissue equivalent,linear dose response.Many studies on various magnesium borate phosphors doped with one or two rare earth dopants showed that these dopants play key roles in the TL process.Purpose: This paper attempts to study the TL characteristics and mechanisms of MgB4O7:Tm,Mn phosphors.Methods: The phosphors were prepared by high temperature solid reaction method,and measured by TL reader and three dimension TL spectrometer.Results: The experiment results show that the TL sensitivity of MgB4O7:Tm,Mn phosphor is about 6.2 times higher than that of LiF:Mg,Ti,and the MgB4O7:Tm,Mn has good thermo stability because of its high temperature of TL peak.Moreover,the TL dose dependence curves were observed to be almost linear in the range of 0.1 Gy to 2 kGy.The TL emission spectrum show that the main glow peak is located at 400oC in wavelength 455 nm.Conclusions: There is competition in the luminescence processes between Tm3+ luminescence centres and Mn activators and probable energy transfer may occur from Mn2+to Tm3+.The MgB4O7:Tm,Mn may be a good candidate of TL phosphor in dosimetry at high temperature condition.关键词：MgB4O7;Tm;Thermoluminescence
- 12
- |
- 115
- |
- 1
发布时间：2021-06-03 - 摘要：Background: Recently,the prompt gamma-rays neutron activation analysis method is wildly used in coal analysis and explosive detection,however there were less application about landmine detection using neutron method especially in the domestic research.Purpose: In order to verify the feasibility of Thermal Neutron Analysis（TNA） method used in landmine detection,and explore the characteristic of this technology.Methods: An experimental system of TNA landmine detection was built based on LaBr3（Ce） fast scintillator detector and 252Cf isotope neutron source.The system is comprised of the thermal neutron transition system,the shield system,and the detector system.Results: On the basis of the TNA,the wide energy area calibration method especially to the high energy area was investigated,and the least detection time for a typical mine was defined.In this study,the 72-type anti-tank mine,the 500 g TNT sample and several interferential objects are tested in loess,red soil,magnetic soil and sand respectively.Conclusions: The experimental results indicate that TNA is a reliable demining method,and it can be used to confirm the existence of Anti-Tank Mines（ATM） and large Anti-Personnel Mines（APM） in complicated condition.关键词：Thermal neutron analysis;Landmine detection;LaBr3（Ce） detector
- 13
- |
- 162
- |
- 6
发布时间：2021-06-03 - 摘要：Background: Airborne gamma-ray spectrometry is made up of multiple NaI（Tl） detector,but the detectors have the different level of noise.Purpose: Aimed at reducing the affection of noise,a weighted least square fusion estimation algorithm is presented to extract the Spectra Characteristics.Methods: The method doesn’t need any prior knowledge on the detector,but carries on the variance estimated on-line these data and timely adjust weights of various fusion sensors in order to make the mean-square error of fusion results least all the time.Results: It is used to process the date come from the standard model,the results show that measurement error range of 40K decreased from 17% to 12%.Conclusions: The result has shown that the method can dramatically decrease the error and improve the accuracy.关键词：Airborne gamma-ray spectrometry;Weighted least square estimation;Data fusion;Variance estimation
- 16
- |
- 111
- |
- 2
发布时间：2021-06-03 - 摘要：Background: Absolute dating is the key technical issue of Quaternary glacial research.Optically stimulated luminescence（OSL） has been increasingly applied to Quaternary glacial dating in recent years.However,problems such as insufficient bleaching,low luminescence sensitivity,high thermal transfer effect,etc,still remain.Purpose: In order to investigate the applicability of equivalent dose（De） determination of glacial sediments by different OSL methods,six samples were collected from the Yingpu Valley of eastern Qinghai-Tibetan Plateau（two samples from modern glacial sediments,three from moraines and glacial terrace attributed to Neoglacial and one from a moraine attributed to the last glaciation）.Methods: The Des were determined by SAR combined SGC technique,using three methods: quartz large aliquot（6 mm） BSL,small aliquot（2/3 mm） BSL and polymineral IRSL.Results: Des determined by SGC are consistent with Des determined by SAR protocol.Comparison of three methods shows that IRSL De>large aliquot BSL De>small aliquot BSL De.Des of polymineral IRSL are obviously higher than quartz BSL.Conclusions: It is obviously that feldspar is more difficult to reset than quartz,thus is not suitable for dating glacial sediments in this region.Quartz large aliquot method is suitable for well bleached glacial samples.Due to the low luminescence sensitivity of quartz,small aliquot method showed poor luminescence characteristics.Moreover,this method cannot distinguish the poor bleached grains in this measurement.However,it is possible that quartz small aliquot,even single grain method could be used to date older or brighter glacial samples.More works are required to solve the problems we have encountered in dating low sensitivity glacial sediments.关键词：Optically stimulated luminescence;Equivalent dose;Single-aliquot regenerative-dose;Standardized growth curve;Small aliquot;Glacial sediments
- 12
- |
- 210
- |
- 6
发布时间：2021-06-03 - 摘要：Background: An enormous amount of liquid radioactive wastes（LRW） was produced by nuclear power plants operation and the reprocessing of spent nuclear fuel.It is necessary to remove 137Cs from LRW to reduce the volumes of waste that require solidification prior to final disposal.Purpose: This paper aimed to study the ion exchange mechanism and uptake behavior for cesium of Ammonium Molybdophosphate（AMP,（NH4）3P（Mo3O10）4.xH2O） in more detail.Methods: Two samples of AMP（AMP-1,AMP-2） were synthesized by different precipitation reactions and they were analyzed by X-ray diffraction（XRD） and Fourier transform infrared spectroscopy（FTIR）.The uptake behavior of AMP-2 for Cs+ under different conditions,such as temperature,contact time,competing ions was investigated through batch experiments.Results: The results show that the adsorption reaches equilibrium in 10 min.The adsorption kinetics can be described by the pseudo second-order equation quite well（R2>0.999）.The existence of Na+and K+have negative effects on the uptake of Cs+,while with K+concentration enrichment,the adsorption capacity of Cs+ decreases faster.Conclusions: The results support the theory of isomorphous exchange of Cs ions for ammonium ions.In addition,AMP has the potential to be a very useful ion exchanger in treatment with nuclear waste solution for removal of137Cs.关键词：AMP;Cs+;Uptake
- 13
- |
- 234
- |
- 9
发布时间：2021-06-03 - 摘要：Background: Monte Carlo simulation techniques are presently considered to be the most reliable method for radiation therapy treatment planning.However,long simulation times involved when using the general-purpose Monte Carlo code systems have led to the development of special-purpose Monte Carlo programs.Purpose: This paper attempts to improve computing efficiency for dose calculation in the EGSnrc modeling of clinical linear accelerator by selecting proper parameters.Methods: Several variance reduction techniques including uniform bremsstrahlung splitting,selective bremsstrahlung splitting,directional bremsstrahlung splitting are applied in BEAMnrc simulating medical accelerator treatment head to generate phase-space file which is selected as a source for DOSXYZnrc simulation,both photon splitting and particle recycling are used to improve the efficiency in the calculation of dose profile in water phantom.Results: The splitting number for maximum efficiency in directional bremsstrahlung splitting（no electron splitting） is 2500 in the BEAMnrc simulation.The highest efficiency of DOSXYZnrc simulation is given when photon splitting number is set to 40.Conclusions: Efficiency can be significantly improved by setting appropriate bremsstrahlung splitting and optimized photon splitting number and particle recycling number.关键词：EGSnrc;Dose;Computing efficiency
- 12
- |
- 97
- |
- 1
发布时间：2021-06-03 - 摘要：Background:99mTc-MIBI was used as myocardial perfusion SPECT.However,the high accumulation of tracers in the liver and lung may hinder the detection of flow abnormalities in myocardium.Purpose: 11C-Triphenylmethylphosphonium（11C-TPMP） was a lipophilic cation,has been investigated as a positron emission tomography（PET） agent for myocardial and tumor imaging to provide a better temporal and spatial resolution than SPECT.Methods: 11C-TPMP was prepared by reacting [11C]methyl trifalte with In-LOOP method.Biodistribution studies in mouse were performed.And micro PET was performed with rat,and compared with 4-[18F]fluorophenyl triphenylphosphonium ion（18F-FTPP）.Results: The results showed that the 11C-TPMP labeling yield was over 90%,the radiochemical purity was over 98%.The biodistribution showed high accumulation of radioactivity in the heart（71.9±19.9）%ID.g–1 at 5 min and（12.87±0.81）%ID.g–1at 60 min post injection.The heart/liver ratios were 11.57 and 3.2 at 5 min,60 min respectively.Micro PET scans showed distinct accumulation of 11C-TPMP in the myocardium from 20 min to 60 min.The liver had very lower accumulation of radioactivity.Conclusions: 11C-TPMP was a promise PET perfusion agent for myocardial.It would be useful in clinical with In-LOOP synthesis.关键词：Myocardial perfusion agents;PET;11C-TPMP;In-LOOP synthesis
- 11
- |
- 81
- |
- 0
发布时间：2021-06-03 - 摘要：Background: Non-steroidal anti-inflammatory drug Indomethacin have been used in the treatment of fever,pain,inflammation and rheumatic disease.In recent years,some researches have confirmed that Indomethacin have the ability of assistant therapy on many kinds of malignant tumors,such as colon cancer,gastric cancer and lung cancer.Purpose: To evaluate the effect of Cisplatin combined with Indomethacin and Histamine-Indomethacin to Lewis lung cancer.Methods: 40 male Kunming mice were used to establish Lewis lung cancer model.They were randomly divided into four groups: Cisplatin treatment group,Cisplatin+Indomethacin treatment group,Cisplatin+Histamine-Indomethacin treatment group and control group.Each mouse was given the PET/CT imaging and taken orbital blood for 0.2 mL before and after the treatment.Histological detection was given.Results: Ratio of targets were significantly different after the treatment,especially in Cisplatin+Histamine-Indomethacin treatment group.Each group TNF-α levels were increased after treatment and the Cisplatin+Histamine-Indomethacin treatment group was the most obvious.There was no obvious difference in tumor inhibiting rates.Conclusions: The results showed that Cisplatin combined with Histamine-Indomethacin could inhibit tumor growth and promote apoptosis of tumor cells better.The changes of the ratio of targets could reflect the effect of the chemotherapy drugs earlier.关键词：Indomethacin;Lewis lung cancer;TNF-α;Positron;18FDG-PET/CT
- 13
- |
- 98
- |
- 0
发布时间：2021-06-03 - 摘要：Background: The magnets exciting current ripple is required to be less than 10–6 for the proton medical accelerator under construction.Purpose: In order to observe the ultra-low current ripple,we design and set up a testing platform based on the ADC card used for digitalized power supplies.Methods: The system performance is analyzed,tested,and the observation is compared with the oscilloscope measurement.Results: Using this platform,the ultra-low current ripples are observed on several magnet power supplies.Conclusions: The method is experimentally proved suitable for the observation of current ripples of 10–6versus hundreds DC current.关键词：Proton medical accelerator;Current ripple;Current ripple observation;FFT
- 13
- |
- 121
- |
- 3
发布时间：2021-06-03 - 摘要：Background: The flow patterns of two phase flow will directly influence the heat transfer and mass transfer of the flow.Purpose: By wavelet analysis of the pressure drop experimental data,the wavelet coefficients of different frequency can be obtained.Methods: Get the wavelet energy and then train them in the model of BP neural network to distinguish the flow patterns.Introduced the implant gray neural networks model and use it for the two phase flow for the first time.At the same time,set up the method of training the pressure data and wavelet energy data in the support vector machine.Results: Through treatment of the gray layer,the result of the neural network is more accuracy.It can obviously reduce the effect of data marginalization.The accuracy of the pressure drop Lib-SVM method is 95.2%.Conclusions: The results show that these three methods can make a distinction among the different flow patterns and the Lib-SVM method gets the best result,then the gray neural networks,and at last the BP neural networks.关键词：Wavelet;Two phases flow;Flow pattern;Gray neural network;Lib-SVM
- 15
- |
- 179
- |
- 0
发布时间：2021-06-03 - 摘要：Background: This paper introduced a device for tandem accelerator project,designed for the radioactive target source module maintaining and testing.Purpose: The module is required to be lifting,rotary and precise orientation in technology.Methods: We designed the structure of rotary drum,supporting drum and screw lifting device to achieve the function.In circumference,we adopt the project with electro-motion cursory locate,hand-motion precise locate,sensor location detect and cylinder locate pin,the measure is safe and trustiness.Results: Via experimentation,all technology targets are fulfilled,and the rationality and reliability of the device has been validated.Conclusions: The successful development of this device provides a good direction and reference for radioactive areas such as accelerator,hot cell,reactor etc.,and can be adapted to its capability of long-distance shield operating,maintaining or testing.关键词：Hot cell;Module;Orientation precision;Support and rotary
- 13
- |
- 62
- |
- 0
发布时间：2021-06-03 - 摘要：Background: Low-background gamma-ray spectrometer is used widely.Low-background laboratory with good shielding performance can reduce the indoor background values effectively,and reduce the impact of the background on low background gamma spectrometer measurements,but currently there were few literatures on the low background laboratory design.Purpose: This paper attempts to propose a design for a low background laboratory with good shielding performance,and effectively improve the sensitivity of instrument.Methods: We analyzed the various factors（cosmic ray,radon and its progeny,the earth’s natural gamma radiation,and building material） affecting the indoor background,and carried out calculation and analysis on different factor.Results: It is found that radon and radon progeny had almost no effect,and cosmic rays and building materials were the main influence factors.Conclusions: In view of the different influence factors on the background,we can design a low-background laboratory which meets the requirements by taking different shielding measures.关键词：Low-background;Influence factors;Analysis;Shielding measures
- 12
- |
- 138
- |
- 3
发布时间：2021-06-03
- 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：675265 Visits Today：341
0