最新刊期
      卷 0 ， 期 0 ， 2020
      • XU Chunyan1,2 YU Feng1,2 SUN Lihua1,2 TANG Lin 1 HU Xiaojian3 HE Jianhua 1 1
        Issue 11, (2008)
        摘要：The Multi-wavelength Anomalous Dispersion(MAD) method is an important method for three-dimensional structure determination of protein crystals.Diffraction datasets of the C-terminal fragment of Sau3AI crystal were collected at three different wavelengths.The structure of Sau3AI-C was solved by MAD method.It shows that this structure is similar to DNA mismatch repair protein MutH.Structural analysis indicates that the cleft in the middle of the structure is the potential binding site for DNA.  
        关键词：C-terminal domain of Sau3AI;Multi-wavelength anomalous dispersion;Crystal structure   
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        发布时间：2021-03-12
      • QIN Lizhao1,3 WU Zhenglong2 ZHANG Xu1 LIU Andong1 LIAO Bin1 1
        Issue 11, (2008)
        摘要：High internal residual stress in diamond-like carbon(DLC) films is a major factor that hinders thick film fabrication.In order to solve this problem,metal vapor vacuum arc(MEVVA) technique was used.DLC film was deposited by filtered cathodic arc deposition,and Ni ions were implanted into the film.By repeating the deposition and implantation,DLC:Ni films of 10 and 15 layers and in thickness of about 1.0 μm and 1.5 μm,respectively,were fabricated.A series of structure and property tests were carried out.The results show that the internal residual stress is released effectively,with increased adhering between the film and substrate.The sp3 contents,the hardness and the elastic modulus of the films are high.These indicate that this method is a feasible technique to fabricate thick DLC films.  
        关键词：MEVVA source;Diamond-like carbon film;Multilayer film;Thick film   
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        发布时间：2021-03-12
      • LIAO Shuqing1 CHENG Cheng1 ZHENG Shuxin1 LIN Yuzheng 1 JING Xiaobing2 MU Fan2 PANG Haifeng 2 1
        Issue 11, (2008)
        摘要：This paper presents experiments of a double-pulsed high voltage system on a miniature linear induction accelerator(Mini-LIA).The double-pulsed voltage with the hundreds of ns interval is generated by an insulation and junction system.The system can conflux two pulses generated from two pulse power systems into a double-pulse and insulate the affection between them.The experiments show that the interval of the double-pulse can be changed from hundreds of ns to μs.With the result a conclusion is that the multi-pulse with the hundreds of ns interval can be generated by an insulation and junction system from multiple pulse power systems.  
        关键词：Mini-LIA;Double-pulses in interval of μs to hundreds of ns   
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        发布时间：2021-03-12
      • XU Jianguo LI Hang ZOU Yubin TANG Guoyou GUO Zhiyu ZHANG Guohui GUO Li’an WEN Weiwei ZHANG Xueshuang
        Issue 11, (2008)
        摘要：Using the CR-39 track detector stack,the mono-energetic neutron spectra for En= 5 MeV and 2 MeV from accelerator D(d,n) reaction were measured.The spectrum measurement of neutrons emitted from thick beryllium target irradiated by 3 MeV or 1.5 MeV d beams from the 4.5 MV accelerator at Peking University was performed.The results agree with that of the time-of-flight method.  
          
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        发布时间：2021-03-12
      • SHI Wen ZENG Zhaoqin CHEN Zhiyong XU Runxiang
        Issue 11, (2008)
        摘要：Ultra-high molecular weight polyethylene(UHMWPE) was implanted with Ar+.The modified surfaces were characterized by OM,AFM and NTM and FT-IR.And,tribological behaviour of UHMWPE was evaluated using a tribometer.The results show that alterations in surface colour,morphology and microstructure of UHMWPE were induced by Ar+ implantation,and the mechanical properties in terms of microhardness and elastic modulus were improved.The wear properties of modified UHMWPE were enhanced significantly,both in dry friction and under deionized water lubrication.The degree of property improvement increased with the implantation dose,with increasing friction coefficient,though.  
        关键词：UHMWPE;Ion implantation;Tribology   
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        发布时间：2021-03-12
      • WEI Biao1 MA Xiaoxin1 JIN Wei2 FENG Peng1 MI Deling1 1
        Issue 11, (2008)
        摘要：Quantitative neutron digital imaging is an important means of NDT(Non-destructive Testing) and NDE(Non-destructive Evaluation).Scattering neutrons have an adverse effect to quality of neutron images when quantitative analysis has to be made in NDT.For quantitative neutron imaging instrument,the principle of imaging degradation caused by neutron scattering is analyzed,and the scattering degradation process is represented by the supposition of PSF(Point Spread Function) superposition.On the basis of constructed PSF model of neutron imaging,a space-domain iterative algorithm applied to scattering correction for this instrument is proposed.The result shows that after correction,for different shapes of H2O samples at different sample-to-detector distances,the scattering component affecting imaging quality of the instrument is apparently restrained,and thickness of the samples evaluated from the processed image approaches their real thickness.This algorithm proves to be practical and effective.  
        关键词：Quantitative neutron imaging instrument;Neutron scattering correction;Point spread function;Iterative algorithm;H2O sample   
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        发布时间：2021-03-12
      • YU Lixia LI Wenjian DONG Xicun ZHOU Libin MA Shuang
        Issue 11, (2008)
        摘要：Young shoots of Dahlia pinnata Cav cultivar were irradiated by 80 MeV/u 12C6+ ions.The differences at DNA level between dwarf mutant and wild type were detected by using RAPD(Random amplified polymorphic DNA) method.The results showed that there were different polymorphic bands induced by 18 primers among the tested 25 primers,and the ratio of polymorphic bands and total bands accounted for 19.57% after 1.80×108C6+/cm2 irradiation.Meanwhile,after 1.08×108 C6+/cm2 irradiation the polymorphic bands were induced by only 6 primers and the ratio accounted for 5.76%.Using the Jaccard formula,statistic analysis of amplified bands were obtained and it showed that after 1.80×108 C6+/cm2 and 1.08×108 C6+/cm2 irradiation the similarity index were 0.65 and 0.92 respec-tively.The results suggested that DNA should prone to mutant at high doses,and high dose irradiation might be more effective in corn improving and mutagenic breeding.  
        关键词：Carbon ion;Dahlia pinnata Cav;Dwarf mutant;RAPD   
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        发布时间：2021-03-12
      • LI Zhen LIU Yanyan WU Minghong JIAO Zheng ZHAO Bing
        Issue 11, (2008)
        摘要：SnO2 gas sensors were irradiated by 1.75 MeV electron beams and effects of the EB irradiation on the performance of the sensors were studied.The results showed that sensitivity of the irradiated SnO2 sensors to hydrogen and ethanol were greatly improved.The sensitivity and coefficient of selectivity to hydrogen and ethanol were enhanced with increasing doses,whereas the response and recovery time decreased.Mechanism of the sensitivity improvement of the irradiated SnO2 sensors was discussed with the adsorption theory on surface.  
        关键词：SnO2;Gas sensors;Electron beam irradiation method;Improvement   
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        发布时间：2021-03-12
      • XIA Xiulong REN Xingbi YANG Tongzai FU Zhonghua
        Issue 11, (2008)
        摘要：The influencing factors on CECE’s separation of hydrogen isotopes were comprehensively investigated with a theoretical model.The separation factor of electrolysis cell αele has a remarkable influence on stripping efficiency and enrichment,and it is an effective way to improve enrichment by decreasing holdup of electrolysis cell.The separation performance at feeding point 1.5 m is better than that of 3 m,stripping efficiency and enrichment has a linear relationship with mass transfer coefficient in the range 3～4 mol·m-3·s-1.For all influencing factors,HD/H2O and HT/H2O have similar tendency,and HT/H2O has better separation performance than HD/H2O for the inherent thermodynamic difference of the two systems.  
        关键词：Hydrogen isotopes separation;CECE;Tritium   
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        发布时间：2021-03-12
      • TANG Xiaolan1 TANG Ganghua2,3 LIAO Wenjie1 1
        Issue 11, (2008)
        摘要：Aminopolyether(K222) is a commonly used catalyst in the routine preparation of [18F]-labeled tracers as PET imaging agents.Determination of residual K222 levels in [18F]-labeled radiopharmaceuticals is a quality control criterion required before they can be released for human use.However,there is no simple and rapid method for the determination of K222 levels.A universal iodine-vapor TLC stain method was developed for the semiquantitative analysis of K222 levels in [18F]-labeled radiopharmaceuticals in this study.Compared with the spectrophotometry and the potassium permanganate TLC stain approach,the iodine-vapor TLC stain method is simple,rapid,accurate and reliable.It can be used as a routine method for the determination of K222 levels.  
        关键词：[18F]-labeled radiopharmaceuticals;Aminopolyether(K222);TLC;Iodine-vapor stain   
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        发布时间：2021-03-12
      • ZHANG Zhongshu WANG Guohong
        Issue 11, (2008)
        摘要：125I-LEP was prepareded by 125I with indirect iodination and direct iodination respectively to develop RIA for method comparison.For the indirect iodination,BH agent was iodinated by ch-T,then conjugated to leptin in ice bath.For the direct iodination,LEP was iodinated by ch-T with direct method.The specific radioactivity of 125I-LEP with indirect iodination was 1.43 MBq/μg,the total labeling rate of 125I was 37.8%,the sensitivity was 0.25 μg/L.The standard curve(0.5～30 μg/L) was stability with the B:B0 from 92.7%～17.5% to 94.6%～22.8% in 45 days.For the direct iodination,the specific radioactivity of 125I-LEP was 1.79 MBq/μg,the total labelling rate of 125I was 41.4%,the sensitivity was 0.37 μg/L.The standard curve(0.5～30 μg/L) was stability with the B/B0 from 87.7%～23.7% to 91.4%～35.2% in 44 days.The standard curve stability of the 125I-LEP prepared by the indirect iodination was not much better than that by the direct iodination in 45 days.They can satisfy the needs in clinic use.Which were worth of additional exploration to enhance the quality in RIA of LEP.  
        关键词：Leptin;RIA;Indirect labeling;125I   
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        发布时间：2021-03-12
      • YIN Xiaohua LAN Xiaoli WANG Ruihua LIU Ying ZHANG Yongxue
        Issue 11, (2008)
        摘要：Cardiac myocytes were obtained from neonatal rat heart and cultured.HSV1-tk,chosen as the reporter gene,was inserted into adenovirus vector(Ad5-tk),and the recombinant adenovirus infected neonatal cardiac myocytes with multiplicity of infection(MOI) of 20,40 and 80.MTT assay was used to detect the viability of infected cardiac myocytes,and semi-quantitative reverse transcriptase polymerase chain reaction(RT-PCR) was applied to determine HSV1-tk mRNA expression in the infected cells.The accumulation of 125I-FIAU into infected cardiac myocytes was detected as uptake rate.The survival rate of infected cells had negative correlation with time,and it decreased with higher viral multiplicity of infection(MOI).After transferred for 24 h,the cardiac myocytes showed significant expression of HSV1-tk mRNA,while the control groups showed negative.Moreover,the exogenous gene expression in the infected cells at MOI 40 was significantly higher than in the ones at MOI 20(P<0.01).The cardiac myocytes infected with increasing titer of Ad5-tk showed positive correlation between uptake rate and time,and the uptake rate of 125I-FIAU in the MOI 40 group was significantly higher than all the other groups(P<0.01).The HSV1-tk reporter gene could be transferred into the neonatal cardiac myocytes successfully with adenovirus vector,and encoded for HSV1-TK catalyzing phosphorylation so as to accumulate the marker substrates 125I-FIAU.The uptake rates,correlated to the uptake time,were the highest with transferred titer 40 at all the time points.This provides some cellular evidence for cardiac imaging of reporter gene in vivo.  
        关键词：Reporter gene;Reporter probe;Adenovirus;Cellular uptake;Cardiac myocytes   
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        发布时间：2021-03-12
      • WANG Mingwei ZHANG Yingjian ZHANG Yongping YUAN Huiyu
        Issue 11, (2008)
        摘要：18F-Fluoroethylcholine(18F-FeCH),a 18F-labeled choline derivatives,is a very sensitive molecular imaging agent for diagnosis of prostate cancer and other types of cancers,indicating a promising future for clinic applications.In this study,automatic synthesis of 18F-FeCH was developed using a "two-step one-pot" method modified from Explora FDG4 synthesis module that are commercially available.The first step is the nucleophilic displacement reaction of 18F-fluoride and 1,2-bis(tosyloxy)ethane at 90°C for 5 min to form labeled intermediate 18F-fluoroethyltosylate.The second step is to form alkylation between 18F-fluoroethyltosylate and N,N-dimethyl-2-hydroxyethylammonium at 100°C for 8 min.The target product of 18F-FeCH was obtained via Sep-pak cartridge separation with about 30% of radiochemical yields(no decay corrected) and more than 99% of radiochemical purity within 65 min of total synthesis time.  
        关键词：18F-FeCH;Choline;Molecular imaging agent;PET/CT;Automated synthesis   
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        发布时间：2021-03-12
      • LIU Kefu1 WANG Shaorong2 ZHONG Heqing2 XU Yan2 PAN Yuan2 1
        Issue 11, (2008)
        摘要：This paper introduces the design of high pulsed power supply system for producing pulsed high magnetic field up to 70 T.This system consists of 58 sets of 55 μF of capacitor bank which provides 1.0 MJ energy storage.A set of vacuum closing switch is chosen as main switch for energy discharge into magnetic coil.A crowbar circuit with high power diodes in series with resistor is used to absorb the redundant energy and adjust pulse width.The resistance of magnetic coil changing with current is deduced by energy balance equations.A capacitor-charging power supply using a series-resonant,constant on-time variable frequency control,and zero-current switching charges the capacitor bank in one minute time with high efficiency.The pulsed power supply provides adjustable current and pulse width with 30 kA peak and 30 ms maximum.The primary experiments demonstrate the system reliability.This work provides an engineering guidance for future development of pulsed high magnetic field.  
        关键词：Pulsed high magnetic field;High power pulsed supply;Magnetic coil   
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        发布时间：2021-03-12
      • HAO Kuihong1,2 ZHAO Lin2 CAO Yongna2 WANG Huaxiang1 1
        Issue 11, (2008)
        摘要：A compact detector system matched to small size CdZnTe detectors has been developed for low energy γ-ray measurement.The linear array system has 16 channels of low noise nuclear read-out electronics.The principle of operation and the results of the system are presented.At room temperature,for 241Am 59.5 keV γ-ray,the total noise of each channel detector system is about 8.9 keV(FWHM),and its count rate capability is about 9×104/s.  
        关键词：Low energy gamma-ray;CdZnTe detectors;16 Channels’ nucleonic instrumentation;Count rate capability   
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        发布时间：2021-03-12
      • HAO Zuyue QI Xin ZHANG Jing
        Issue 11, (2008)
        摘要：In drift tube linac(DTL),the particle focusing problem is provided by the drift tube embedded with quadruple magnet(Q).If the quadruple magnet is excited by DC power supply,it would result in thermodynamics distortion of the drift tube.A feasible scheme for the rectangle pulse power excitation is described in this paper.The simulation and the experimental studies on the power supply model prove the feasibility.  
        关键词：Drift tube linac;Quadruple magnet;Rectangle pulse   
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        发布时间：2021-03-12
      • CUI Chengyi ZHANG Jinhai ZHOU Xingfei
        Issue 11, (2008)
        摘要：Temperature effects on fibrosis growth of glucagon was investigated by atomic force microscope.The protein fibers exhibit different surface structures under various incubation temperatures.At low temperature(20°C),a majority of fibers take on helix structure.At high temperature(50°C),the bulk of fibers do not have helix structure and they become a little thinner and much longer than that at low temperature.At midst temperature(35°C),the amount of the two types of fiber are almost the same,and the thinner fiber grow much faster than the winder one at 35°C.These indicate that the two types of fiber have a different structure.In addition,we found that once the structure is formed,each type fiber was stable at different temperatures.  
        关键词：Glucagon;Temperature;Fibrillation;Atomic Force Microscope   
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        发布时间：2021-03-12
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