最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：Higher-harmonics suppressors are designed for Beamline 4B7A and 4B7B at Beijing Synchrotron Radia- tion Facility (BSRF) in order to improve spectral purity of their output monochromatic light in energy region of 1200 —2100 eV and 45—450 eV respectively. They consist of plane reflectors whose coatings and grazing incidence angle have been fixed. The performances of both suppressors have been calculated and the results are also presented in graphical form.关键词：Synchrotron radiation;Beamline;Higher-harmonics suppressor
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发布时间：2021-03-12 - 摘要：This paper describes the development of an analog active integrator applied in pulsed magnetic field measurement system. To meet precision requirement of the measurement system, the integral circuit was designed and the errors of real active integral circuit parameters were analyzed. Rationality of the proposition was proved and some relative parameters required for rational design so that errors can be kept within the permissible range were given. Test and experiment of the circuit demonstrate that this analog active integrator can meet design requirement of the pulsed magnetic field measurement system.关键词：Integrator;Injection;Extraction;Pulsed magnetic field
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发布时间：2021-03-12 - 摘要：In an attempt to explore mechanisms of moss as air pollution biomonitor, moss samples were exposed for one month at Shanghai Iron and Steel Research Institute (SISRI, as a pollution site) and Shanghai Institute of Applied Physics (SINAP, as a control site) simultaneously. Elemental distributions in micro areas of the leaf and stem, and the whole moss tissue as well, were determined using synchrotron radiation X-ray fluorescence (SRXRF) method. The contents of metal elements of Pb, Cu, Fe, Ni, Mn, Zn, Ca, K in the leaf surface and stem slice were obtained. The re- sults showed that the metallic ions were not distributed uniformly in the polluted samples. In particular, K, Ni, Fe and Pb were concentrated in the leaf apex and the intermediate rib. In samples of the air pollution, excessive Pb was ad- sorbed and deposited in the leaf, causing serious damage to the plant growth and their microstructure and inhibiting the plant’s normal absorption to nutritive elements, such as K and Ca.关键词：Moss;Biological monitor;Synchrotron radiation;X-ray fluorescence microprobe;Air pollution
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发布时间：2021-03-12 - 摘要：Shell particles in micrometer level have been prepared by a jet milling, and it was used as filler to modify the properties of epoxy resin (EP) by melting-blending. The organic phase of the shell particles was much helpful to improve the interfacial intension. When appropriate content of shell particles were added to EP matrix, the free vol- ume size and its intensity of the composites decreased, but the intensity of the second lifetime I2 increased. It was at- tributed to the formation of the interfacial layers between the shell particles and EP matrix. This good interfacial property was necessary for efficient stress transfer between the particles and EP matrix. Therefore, the mechanical properties of the composites were approved remarkably.关键词：Epoxy resin;Free volume;Positron annihilation;Toughening
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发布时间：2021-03-12 - 摘要：Aquifers are fully classified according to vertical velocity and the change of tracer’s concentration de- tected by radioactive isotope in borehole, and the applicability of the dilution formula is summarized completely. It is pointed that the horizontal seepage velocity in gushing aquifer can’t be obtained by the formula. For the aquifer with natural hydraulic gradient, its discharge can still be calculated by correlative well flow formulae. A method is ad- vanced to gain the coefficient of permeability with combining tracer technique and water injection experiment in a borehole. Firstly, we can measure the concentration of the tracer in the borehole along with time in natural condition, and calculate the vertical velocity and discharge. Then, we inject water in the borehole and obtain a different level in the borehole, and gain a set of value about velocity and discharge in the state. Finally, the coefficient of permeability in the aquifer is got. Moreover, the calculating formulae concerning steady flow and unsteady flow are discussed re- spectively. This simple and practical method can also be applied to sopping aquifers as such as gushing aquifers, which extends the applied range of tracer technique. At last, the effective application of this method is docu- mented by a practical example.关键词：Radioactive isotope;Generalized dilution formula;Vertical flow;Tracer logging;Water injection ex- periment;Coefficient of permeability
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发布时间：2021-03-12 - 摘要：The dc electronic parameters and annealing factor change of SiGe HBT irradiated by neutron and gamma-rays in a pulsed reactor were measured. The dc common emitter static current gain of the SiGe HBTs de- creased by about 20% after the irradiation with 1×1013 cm-2 neutron fluence and 257 Gy(Si) in gamma-ray total dose. The base current and the junction leakage current increased, whereas the collector current and the breakdown voltage decreased for SiGe HBT after the irradiation. Mechanisms of the radiation-induced damage to SiGe HBT are dis- cussed.关键词：SiGe HBT;Transient irradiation effects;Reactor;Annealing
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发布时间：2021-03-12 - 摘要：The study aims at exploring mechanisms of the biological effect induced in human hepatoma SMMC-7721 cells irradiated by high LET heavy ions. Carbon (12C6+) and argon (40Ar+) ions from Heavy Ion Re- search Facility at Lanzhou (HIRFL) and pulse-field gel electrophoresis were used in this study. The results showed that in the given dose range the DSB induction increased linearly with dose and the slope of dose-effect curve of the 40Ar+ ions with higher LET was bigger. Meanwhile we found that when dose increased there were different varieties of the distribution of DSB fragments induced by ions with different LET and the quick repair to DSB was completed in 30 minutes and then came the slow repair phase for two kinds of irradiation. For the 40Ar+ ions irradiation with higher LET the amount of repaired DSB was larger than 12C6+ ions irradiation in both repair phases and there was lit- tle distinction between the residual DSB induced by two kinds of irradiation. The results approve the linear relation- ship between DSB induction and dose and display the influence of ion kind to the slope of dose-effect curve. As well as the results affirm the non-random distribution of DSB induced by heavy ions and the two phase mode of DSB re- pair and show the synchronously introduced impact to the distribution of DSB by LET, ion kind and dose. Slow repair and misrepair should be given attention when research on repair to DSB induced by heavy ions is involved.关键词：Heavy ions;DSB;LET;DSB repair
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发布时间：2021-03-12 - 摘要：Samples of hydrogen isotope-absorbed titanium films, i.e., H/D–Ti, D/T–Ti, D–Ti and T–Ti, were ana- lyzed with elastic recoil detection (ERD) method at 30° to beam incidence of 7.4 MeV 4He ions, so as to assess the isotopic effect of depth distribution in the metal hydride. By incorporating the D distribution in 1.7 μm depth of the HD–Ti sample with the ERD spectra in about 3μm of the D–Ti sample, the simulated H and D depth distributions were obtained. The results show that the H and D concentration increased with depth in the same way in the Ti film. This means that there is no interference between the H and D depth distribution in Ti, and the isotope effect is not patent in the sample preparing process. With the same method the D and T depth distribution in 1.7 μm of the D/T–Ti sample are basically the same, too. As the result has a bigger error because the ERD spectra of D and T are too close to each other, 3.0MeV proton backscattering (PBS) was used for analyzing the D–Ti and H/D–Ti samples. The results show that the distribution trend of D in these two samples were the same, confirming that there is no interference be- tween H and D depth distribution in Ti, and the isotope effect is not patent.关键词：Hydrogen isotopes;Depth distribution;Elastic recoil detection;Proton backscattering
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发布时间：2021-03-12 - 摘要：The adsorption and desorption behaviors of tritium on the surfaces of stainless steel were studied prelimi- narily. After the exposure in the mixed gas of 50% deuterium and 50% tritium (15 MPa mixed gas, 8 hours and 27MPa mixed gas, 6 hours exposure at 503 K), the tritium desorbed at room temperature and during heating up to 1173 K and the total sorbed tritium of the samples were measured. The results showed that the total adsorbed tritium was 857.4 MBq·cm-2, the desorbed tritium was 722.2 MBq·cm-2, the standard deviation of measurement was 6.49%. The tritium released from stainless steel at room temperature and during heating was mostly in the form of HT, The ratio of the free tritium to the total absorbed tritium was 7.34%. There were three peaks in the thermo-desorption spectrums of stainless steel, their desorption temperatures of the three peaks were 439, 530 and 843 K , respectively.关键词：Tritium;Stainless steel;Adsorption;High pressure
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发布时间：2021-03-12 - 摘要：In order to investigate the adverse impact of hypertension SHR rats caused by simulated particle matter (nano ferric oxide) with radioactivity isotope tracer techniques was researched. By measured the radioactivity inten- sity in different tissues in different time point, we got the regular pattern of scavenging particles from pulmonary and the metabolism of the particles in a rat. The ultrafine particles can transport from the pulmonary to blood, then par- ticipated metabolism and expelled out of the body by feces in both hypertension rats and normal rats. The speed of unltrafine particulars transporting to blood is faster than the normal ones and expelled through feces in hypertension animals are less than those in normal rats. In conclusion, the ultrafine particles are more harmful to hypertension pa- tients because the particles can easily transport from lung to blood and be hardly scavenged from body through feces, so the hypertension patients may be the sensitive group by ultrafine particle in the atmosphere.关键词：Hypertension;Nanometer-particles;Radioactivity isotope tracer techniques
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发布时间：2021-03-12 - 摘要：Fe3O4/chitosan magnetic microspheres were prepared with inverse-phase suspension dispersion method. It was modified through the reaction with poly(ethyleneimine) to increase the content of amine group of the adsorbent. The samples were characterized by X-ray diffraction (XRD), FT-IR, and thermogravimetric analysis (TGA). Adsorp- tion performance of the modified chitosan microspheres toward Hg2+ and UO22+ was investigated. The results showed that the concentration of amine group of the adsorbent was 6.47 mmol/g. The adsorption rate was fast due to their small size (15—30 μm). Selective separation of Hg2+ and UO22+ was achieved at pH<3.This was due to the fact that Hg2+ was able to form complexing anion (HgCl3-) with Cl- and adsorb onto the modified chitosan adsorbent through ion-exchange mechanism, but UO22+ could not. The maximum adsorption capacity (qm) was 2.19 mmol/g for Hg2+ and 1.38 mmol/g for UO22+. The adsorption rate constant calculated by Lagergrent equation was 0.087 min-1 for Hg2+, 0.055 min-1 for UO22+. More than 90% desorption efficiency for UO22+ and Hg2+ was achieved using 1 mol/L H2SO4 and for UO22+ using 2 mol/L HCl.关键词：Modified chitosan;Ethylenediamine;Hg2+;UO22+
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发布时间：2021-03-12 - 摘要：The work was to study protective effect of simultaneous modulated accelerated radiation therapy (SMART) on salivary function of nasopharyngeal cancer patients. Forty-six patients were treated by SMART with 2.5Gy/fraction at gross tumor volume to a total does of 70 Gy, and 2.0 Gy/fraction at the clinical treatment volume to a total does of 56 Gy. The SMART was practiced in step-and-shoot mode, one time a day, and five times each week. Fourteen patients were treated by conventional radiation therapy. All the patients received salivary gland function imaging for their uptake index, excretive index and excretive speed, so as to evaluate their degree of salivary function injury. Meanwhile, the dry discomfort in mouth of the patients was recorded and classified. The results showed that the functional indexes of the SMART group were significantly higher than those of the conventional radiation therapy group (P<0.05). The 14 patients treated by conventional radiation therapy showed xerostomia and mucositis, with only one patient in Grade 1, three in Grade 2 and 10 in Grade 3. The patients in SMART group felt much better, with14 of no xerostomia, 18 in Grade 1, 9 in Grade 2, and just 5 in Grade 3. The difference between the two groups is obvious (χ2 =23.52, P<0.005). Therefore, SMART can play a key role in protecting salivary gland function of naso- pharyngeal cancer patients.关键词：Nasopharyngeal cancer;Simultaneous modulated accelerated radiation therapy(SMART);SPECT im- aging of salivary gland;99TcmO4-
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发布时间：2021-03-12 - 摘要：An accelerator-electron microscope interface facility, the first of its kind in China, has been established in Wuhan University. The system consists of a 2×1.7 MV tandem accelerator, a 200kV ion implanter, and a TEM linked by a beam transport system. Ion beams are transported satisfactorily into the target chamber of TEM for in-situ struc- tural studies.关键词：Accelerator;Ion implanter;TEM;Interface facility;In situ
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发布时间：2021-03-12 - 摘要：A communication equipment-RS485 optical router has been developed to satisfy requirements of control system communication network of HIRFL-CSR (Heavy Ion Research Facility at Lanzhou-Cooling Storage Ring). The equipment is compatible with multiple communication protocols, such as Ethernet, RS232 and RS485 standard. It can be used to setup the RS485 communication network quickly and connected to the Ethernet easily. The fiber optical interface is introduced to facilitate the connection with the network of industrial Fiber Optics Communication (FOC), which expands the application field of the equipment in a large extent. This paper introduces the details of the equipment, including the design of the circuit and software, features of the equipment and how it works in the whole control system network. Its application in the HIRFL-CSR control system shows that the equipment is in accordance with the general requirement of automatic control communication system. It could also be used in other industrial automatic control fields.关键词：RS485;Router;Fiber optics communication (FOC);Nut/OS
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发布时间：2021-03-12 - 摘要：In this paper, A nuclear radiation multi-parameter measurement system based on pulse-shape sampling is introduced, including the system’s characteristics, composition, operating principle, experiment data and analysis. Compared with conventional nuclear measuring apparatus, it has some remarkable advantages such as the synchro- nous detection using multi-parameter measurement in the same measurement platform and the general analysis of sig- nal data by user-defined program.关键词：VI;Nuclear electronics;Radiation detection;Nuclear apparatus
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发布时间：2021-03-12 - 摘要：The central timing system is an important part of the central control system on the Experimental Advanced Superconducting Tokamak (EAST), and it is the base of the central control system to control the timing and trigger of every subsystem. Based on the distributed architecture, this project established a central timing system on the EAST Tokamak. The central timing system has the ability to divide the 32 MHz system clock with any integer from 0 to 65535, and it can delay the system trigger signal with the longest delay interval of 4294 s under 1 μs resolu- tion. This timing system is stable and was used successfully in the first physics experiment of the EAST supercon- ducting Tokamak in September 2006.关键词：Tokamak;Distributed;Central timing;Ethernet;Embedded
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发布时间：2021-03-12 - 摘要：Due to its unique physical and chemical properties, DNA has recently become a promising material for building blocks in nanofabrication. Many researches focus on how to use DNA molecules as a template for nanowires. Molecular Combing technique is one of important methods to manipulate DNA molecules by using a water meniscus and form specific DNA nano-structures on surfaces. In this paper, by employing a modified molecular combing tech- nique, special patterns of DNA molecules was formed, and the interaction between liquid flows or meniscus and DNA molecules was analyzed, and the mechanism of manipulating DNA molecules by liquid was studied.关键词：Atomic force microscopy (AFM);DNA;Manipulation;Ethanol;Water flow
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发布时间：2021-03-12 - 摘要：When uncultivated land without erosion is cultivated, the 210Pbex in the depth of tillage, which decreases exponentially with depth, can be mixed in the plough layer. Subsequently, the 210Pbex of the plough layer would gradually diffuse into the plough pan layer owing to the concentration grads of 210Pbex between them, and finally a steady state would come forth as a result of balance between diffusion and decay of the 210Pbex. This process can be considered as one-dimensional diffusion from a thin diffusion source layer with unlimited width to semi-infinite media. This paper describes the process in a quantitative way. The time of the process from initial cultivation to the steady state is about 10 years (y=10.37 a). As in the case of cultivated purple soil of Neijiang in Sichuan province, the downward diffusion coefficient of soils of the plough pan layer is D=0.676 cm2·a-1, which is achieved according to the 210Pbex depth distribution of the soils. Subsequently, the 210Pbex inventory of the plough pan layer of different time after initial cultivation are calculated, and ultimately the process of 210Pbex distribution in the non-eroded purple soils after cultivation is figured out.关键词：Cultivated soils;210Pbex distribution;Steady state;Downward diffusion coefficient
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发布时间：2021-03-12
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