检索结果-南通市图书馆

Beam optics study for energy selection system of SC200 superconducting proton cyclotron

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2018年第9期29卷 222-229页

作者： Xian-Hu Zeng Jin-Xing Zheng Yun-Tao Song Feng Jiang Ming Li Jun-Sheng Zhang Wu-Quan Zhang Lei Zhu Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230031China

To meet the demands on proton therapy in Russia and China, JINR and ASIPP have started to develop a proton therapy facility based on an isochronous superconducting proton accelerator. A 200 Me V/500 n A proton beam will be extracted from the SC200 superconducting proton cyclotron. Due to the energy of the cyclotron being fixed, an energy selection system(ESS) is employed to degrade such energy in order to match the particle energy to a shallower depth. In this article, calculation of beam optics, analysis of beam transmission, and correction of orbit distortion are presented. Studies show that the main factors influencing transmission efficiency of the SC200 ESS beamline are the degrader, collimator, slit, vacuum system, beam diagnostic system, and trajectory correction system. Through the beam optics study, the designed ESS beamline can provide 70–200 Me V proton beam to a treatment room, with a maximum emittance of24 p mm mrad. Also, the controllable momentum spread ranges from 0.1 to 1.0%, which is equivalent to an energy spread from 0.193 to 1.93%. The transmission efficiency about 0.204% can be obtained when the emittance is24 p mm mrad with an energy spread of ± 0.6%.

关键词： proton therapy Beam optics ESS Transmission efficiency Orbit distortion correction

Optical waveguides in LiNbO_3 and stoichiometric LiNbO_3 crystals by proton exchange

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2008年第10期51卷 1479-1488页

作者： LI ShiLing College of Physics and Engineering, Qufu Normal University, Qufu 273165, China School of Physics and Microelectronics, Shandong University, Jinan 250100, China College of Physics and Engineering Qufu Normal University Qufu China School of Physics and Microelectronics Shandong University Jinan China

The formation of optical planar waveguides in LiNbO3 and stoichiometric LiNbO3 crystals by proton exchange was reported. The prism-coupling method was used to characterize the dark-line spectroscopy at the wavelength of 633 and 1539 nm, re-spectively. The mode optical near-field outputs from proton-exchanged LiNbO3 and SLN waveguides at 633 nm were presented. The mode field from stoichiometric LiNbO3 (SLN) waveguide is lighter and more uniform than that from LiNbO3 waveguide, which means the quality of the waveguide in SLN crystal is better than that of the LiNbO3 waveguide. For proton-exchanged LiNbO3 waveguides, the evo-lution of the refractive index profile with annealing was presented. The disorder profiles of Nb atoms in proton-exchanged LiNbO3 waveguides were obtained by Rutherford backscattering/channeling technique. It is shown that the longer the exchange time, the larger the displacement of Nb atoms.

关键词： optical waveguide proton exchange LiNbO3 crystal stoichiometric LiNbO3 crystal

Development of a scintillation detector for real-time measurement of space proton effective dose

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2019年第5期30卷 48-58页

作者： Shou-Jie Zhang Xin-Biao Jiang Da Li Xiao-Ren Yu Liang-Liang Miao Xiao-Jing Song Yan Ma Northwest Institute of Nuclear Technology State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi'an Jiaotong University

In this study, a scintillation detector was developed to measure the space proton effective dose for astronauts based on the proton effective dose conversion coefficients provided by International Commission on Radiological Protection Report No. 116. In the Monte Carlo N-Particle Transport Code X(version 2.6.0) simulation process, by modulating the depth and solid angle of truncated conical holes in an iron shell from lower-energy protons to higher-energy protons, the energy deposited in the scintillator by isotropic protons was nearly proportional to the corresponding effective dose, with a maximum relative deviation of 13.28% at thirteen energy points in the energy range of 10–400 MeV. Therefore, the detector can monitor proton effective dose indirectly in real time by measuring the deposited energy. We calibrated the photoelectric conversion efficiency of the detector at the cobalt source, tested the response of the detector in the energy range of 30–100 MeV in unidirectional proton field, and validated the simulation with the experimental results.

关键词： Effective dose Space proton Scintillation detector ICRP Report No. 116 Deposited energy

Properties of proton Transfer in Hydrogen-Bonded Systems at Finite Temperature

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2002年第10期38卷 407-414页

作者： PANG Xiao-Feng Institute of Life Science and Technology University of Electronic Science and Technology Chengdu 610054 China International Center for Materials Physics the Chinese Academy of Sciences Shenyang 110015 China CCAST (World Laboratory) P.O. Box 8730 Beijing 100080 China

The properties of proton transfer along hydrogen-bonded molecular systems are studied at finite temperature. The dynamic equations of the proton transport along the systems are obtained by using a completely quantummechanics method. From the dynamic equations and its soliton solutions we find out specific heat arising from the motionof solitons in the systems with finite temperature and the critical temperature of the soliton in the protein molecules,which is about 318 K. This shows that we can continuously study some biological phenomena in the living systems bythis model.

关键词： proton transfer, hydrogen bond, critical temperature, specific heat

Body mass index and its effects on liver fat content in overweight and obese young adults by proton magnetic resonance spectroscopy technique

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Hepatology 2018年第12期10卷 924-933页

作者： Duanghathai Pasanta Montree Tungjai Sirirat Chancharunee Warayuth Sajomsang Suchart Kothan Department of Radiologic Technology Faculty of Associated Medical SciencesChiang Mai University Department of Chemistry Faculty of ScienceChiang Mai University National Nanotechnology Center National Science and Technology Development AgencyThailand Science Park

AIM To assess the association between liver fat content(LFC) and weight status in young adults using proton magnetic resonance spectroscopy(1H MRS) technique.METHODSSeventy-eight healthy young adults, between 19-30 years of age participated in this study. This group was then separated into a control of 39 subjects and an overweight/obese group(OW/OB group) consisting of 39 subjects. Blood biochemical quantity and 1 H MRS was performed for LFC assessment.RESULTS LFC was found to be almost three times higher in OW/OB group when compared to the control group. A 48.7% incidence of non-alcoholic fatty liver disease in the OW/OB group was found. Blood biochemical measurements showed statistically higher low-density lipoproteins and triglyceride, lower highdensity lipoproteins, and increased glycosylated hemoglobin and fasting glucose in the OW/OB group. Body mass index was a significant independent predictor for LFC after adjusting for age and sex(multiple linear regression; β = 0.459, P <0.001).CONCLUSION Due to the prevalence of high LFC in the OW/OB group, it can be proposed that weight gain and obesity are sensitive indicators of high hepatic fat content.

关键词： Young adults Overweight Obesity Non-alcoholic fatty liver disease Body mass index proton magnetic resonance spectroscopy Cholesterol

Computer-aided Interpretation of proton Nuclear Magnetic Resonance Spectra (Ⅰ)——An Artificial Intelligence System for Interpretation of proton NMR Spectra of Polymers

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 1993年第8期36卷 897-905页

作者：高令杰赵天增韦贵红梁晓天 The Institute of Chemistry Henan Academy of Sciences Zhengzhou 450003 PRC

An artificial intelligence system for interpretation of proton NMR spectra of polymers is reported in this paper. The system, including spectra data base, knowledge data base and reasoning engine, is based on the characteristics of the proton NMR spectra of polymers and the spectra interpretation experiences of specialist. The system can partly simulate human thinking and interpret proton NMR spectra of polymers at different levels of sophistication. The program in the system was written in Turbo Prolog 2.0 and translated into machine language by computer compiler. It has been tested on an IBM PC/XT computer and a satisfactory result was given.

关键词： artificial intelligence spectra interpretation proton NMR polymer.

Organic ammonium ion-occluded flexible coordination polymers:Thermal activation,structure transformation and proton transfer

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2010年第10期53卷 2144-2151页

作者： XIE LinHua1, LIN JianBin1, LIU XiaoMin1, XUE Wei1, ZHANG WeiXiong1, LIU ShuXia2, ZHANG JiePeng1 & CHEN XiaoMing1 1MOE Key Laboratory of Bioinorganic and Synthetic Chemistry State Key Laboratory of Optoelectronic Materials and Technologies School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China 2Key Laboratory of Polyoxometalates Science of Ministry of Education College of Chemistry, Northeast Normal University, Changchun 130024, China MOE Key Laboratory of Bioinorganic and Synthetic Chemistry State Key Laboratory of Optoelectronic Materials and Technologies School of Chemistry and Chemical Engineering Sun Yat-Sen University Guangzhou China Key Laboratory of Polyoxometalates Science of Ministry of Education College of Chemistry Northeast Normal University Changchun China

Solvothermal reactions of 1,3,5-benzenetricarboxylic acid (H3btc) with cadmium acetate or zinc acetate yielded two compounds formulated as (Me2NH2)[Cd(btc)]·DMA (1) (btc = 1,3,5-benzenetricarboxylate, DMA = N,N-dimethylacetamide) and (Me2NH2)[Zn(btc)]·DMF (2) (DMF = N,N-dimethylformamide). Both are 3-D frameworks with the rutile topology, which are constructed from six-connected dimeric metal cores and three-connected btc linkers. The solvent molecules and counter cations are located in the 1-D channels of the frameworks. A slight difference between the two compounds is the different connectivity modes of the metal atoms with the carboxylate groups of the ligands. However, this slight difference results in distinct flexibilities of the two frameworks. Variable-temperature powder X-ray diffraction studies revealed that the framework of 1 collapses when heated at 180 °C with loss of the guest species, but compound 2 undergoes two structural transformations below 380 °C. Thermogravimetry-infrared spectroscopy analysis for 2 showed that the two structural transformations are induced by separate losses of solvent molecules and counter cations, and that the dimethylammonium cations are eliminated as neutral dimethylamine molecules. IR spectroscopy demonstrated that the protons are transferred from the counter cations onto the uncoordinated carboxylate oxygen atoms on the channel walls. Sorption and proton conduction studies have also been performed for the compounds.

关键词： flexible coordination polymer proton transfer charged metal-organic framework rutile topology proton conduction

Cross-sectional investigation of radiation damage of 2 MeV proton-irradiated silicon carbide

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2018年第4期29卷 72-78页

作者： Xu Wang Yan-Wen Zhang Dong Han Yun-Biao Zhao Zi-Qiang Zhao Ming Zhang Institute of Materials China Academy of Engineering Physics Department of Nuclear Physics China Institute of Atomic Energy State Key Laboratory of Nuclear Physics and Technology Institute of Heavy Ion Physics School of Physics Peking University

Cross-sectional investigation is an important method to study ion irradiation effects in the depth direction. In this study, 2 Me V H^+was implanted in 6 H-SiC single crystals to investigate the effects of light ion irradiation on SiC. Raman spectroscopy and scanning electronic microscopy(SEM) were carried out on crosssectional samples to reveal the in-depth damage states and dopant behavior. The most damaged region is a little shallower than that predicted by the SRIM procedure,owing to the uncertainty in SRIM simulations. Layered structures representing zones of varying damage after2 MeV H ion irradiation are clearly observed. Two bands are observed in SEM images, of which on band corresponds to the damage peak, while the other band at the end of the H ion-affected area is probably a result of H diffusion propelled by a hydrogen-rich layer during irradiation.A charge accumulation effect related with conductivity on the sample surfaces during SEM tests is observed in theH-implanted area. A model is proposed to explain these phenomena.

关键词： SiC proton irradiation Cross-sectional analysis Raman spectroscopy SEM

Fluorescent sensing of anions based on excited state intramolecular proton transfer in N-(3-hydroxy-2- naphthamido)-N′-phenylthiourea

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2009年第6期52卷 786-792页

作者： LI Zhao CHEN YaoHan JIANG YunBao Department of Chemistry College of Chemistry and Chemical Engineering and the MOE Key Laboratory of Analytical SciencesXiamen UniversityXiamen 361005China

A neutral N-amidothiourea-based excited state intramolecular proton transfer (ESIPT) anion receptor bearing an o-hydroxynaphthamide fluorophore and a thiourea binding site, N-(3-hydroxy-2-naphthamide)-N’-phenylthiourea (1a), was designed and synthesized. Fluorescence and absorption response of 1a toward anions were assessed in acetonitrile. IR and NMR experiments indicated that the "OH…O=C" intramolecular hydrogen bond (IHB) in 1a was weak so that it only exhibited the short-wavelength normal emission other than ESIPT fluorescence. Due to the high anion binding affinity of the N-amidothiourea binding site and the formation of a hydrogen binding network in the 1a-anion c omplex, 1a underwent structural change upon anion binding that strengthens the "OH…O=C" IHB, leading to the ESIPT and the observation of the long-wavelength ESIPT emission whereas the normal fluorescence is quenched. On the basis of NMR and fluorescence titrations and control experiments with model compounds, a sensing mechanism of the anion-binding-induced ESIPT was proposed.

关键词： fluorescent sensing anion hydrogen bonding excited-state proton transfer N-(3-hydroxy-2-naphthamido)-N′-phenylthiourea