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Combining Neutron Scattering,Deuteration Technique,and Molecular Dynamics Simulations to Study Dynamics of Protein and Its Surface Water Molecules

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Chinese Journal of Polymer Science 2019年第11期37卷 1083-1091页

作者： Li-Rong Zheng Liang Hong School of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Institute of Natural Sciences Shanghai Jiao Tong University Shanghai 200240 China

Protein internal dynamics is essential for its function. Exploring the internal dynamics of protein molecules as well as its connection to protein structure and function is a central topic in biophysics. However, the atomic motions in protein molecules exhibit a great degree of complexities. These complexities arise from the complex chemical composition and superposition of different types of atomic motions on the similar time scales, and render it challenging to explicitly understand the microscopic mechanism governing protein motions, functions, and their connections. Here, we demonstrate that, by using Neutron scattering, molecular dynamics simulation, and deuteration technique, one can address this challenge to a large extent.

关键词： Neutron scattering Deuteration techniques Molecular dynamics simulations Protein Hydration water Dynamics

Analysis of Dimer Impurity in Polyamidoamine Dendrimer Solutions by Small-angle Neutron Scattering

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Chinese Journal of Polymer Science 2019年第8期37卷 827-833页

作者： Tian-Fu Li Yi-Yun Cheng Yu Wang Hui Wang Dong-Feng Chen Yun-Tao Liu Li Zhang Wen-Ze Han Rong-Deng Liu Zi-Jun Wang Chun-Ming Yang Charl J. Jafta Daniel Clemens Uwe Keiderling China Institute of Atomic Energy Beijing 102413 China Key Laboratory of Regulatory Biology School of Life Sciences East China Normal University Shanghai 200062 China Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201204 China Helmholtz-Zentrum Berlin fürMaterialien und Energie Lise-Meitner-Campus Berlin 14109 Germany

Dimer impurity in the solution of a generation five(G5) polyamidoamine(PAMAM) dendrimer has been investigated by small-angle Neutron scattering(SANS). The existence of dimer impurity in dendrimer solution was evidenced by indirect Fourier transform(IFT) analysis of the SANS data, in which the maximum dimension of particles in solution was found to be about twice the diameter of G5 dendrimer. We then developed an analytical model which accounts for the scattering contribution from both dendrimer monomer and dimer. The experimental data were well fitted by using the established model. The results showed that the amount of dimer impurities is significant for the measured three batches of G5 PAMAM dendrimers.

关键词： PAMAM dendrimer Dimer impurity Small-angle Neutron scattering Scattering model

Neutron Diffraction Investigation of the DyFe11Ti Magnetic Structure and Its Spin Reorientations

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Engineering 2020年第2期6卷 154-158页

作者： Olivier Isnard Eder J.Kinast University Grenoble Alpes Institut Neel du CNRS25 rue des MartyrsGrenoble 38042France Universidade Estadual do Rio Grande do Sul Porto AlegreRS 90010-191Brazil

In this article,we report on the magnetic structure of DyFe11Ti and its thermal evolution as probed by Neutron powder diffraction.A thermodiffraction technique was used to follow the temperature dependence of the magnetic moments,as well as their orientation.The Dy and Fe moments were coupled to each other in an antiparallel manner to form a ferrimagnet,where the easy magnetization direction at 2 K was the[110]axis in the basal(a,b)plane.This magnetic structure underwent two successive spin reorientation phenomena with increasing temperature.A large Dy magnetic moment of 9.7 Bohr magneton(μB)was obtained at low temperatures,and the magnitude decreased rapidly to 7.5μB at 200 K.The largest Fe magnetic moment was observed on the Fe 8i position.A ThMn12-type crystal structure was preserved in the studied temperature range,despite the large changes of the magnetic structure.A sharp tilt was observed at the first-order spin reorientation,TSR1;the angle between the easy magnetization axis and the crystal c axis was reduced from 90°at 2 K to about 20°at 200 K(where c is the easy axis above 200 K);and the Dy and Fe magnetic moments maintained an antiparallel coupling.

关键词： Neutron diffraction Magnetic phase diagram Crystal structure

Neutron-activated biodegradable samarium-153 acetylacetonate-poly-L-lactic acid microspheres for intraarterial radioembolization of hepatic tumors

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World Journal of Experimental Medicine 2020年第2期10卷 10-25页

作者： Yin-How Wong Hun-Yee Tan Azahari Kasbollah Basri Johan Jeet Abdullah Rajendra Udyavara Acharya Chai-Hong Yeong School of Medicine Faculty of Health and Medical SciencesTaylor’s UniversitySubang Jaya 47500SelangorMalaysia School of Biosciences Faculty of Health and Medical SciencesTaylor’s UniversitySubang Jaya 47500SelangorMalaysia Medical Technology Division Malaysian Nuclear AgencyBangi 43000SelangorMalaysia Department of Electronics and Computer Engineering Ngee Ann PolytechnicSingapore 599489Singapore

BACKGROUND Liver cancer is the 6 th most common cancer in the world and the 4 th most common death from cancer worldwide.Hepatic radioembolization is a minimally invasive treatment involving intraarterial administration of radioembolic microspheres.AIM To develop a Neutron-activated,biodegradable and theranostics samarium-153 acetylacetonate(153SmAcAc)-poly-L-lactic acid(PLLA)microsphere for intraarterial radioembolization of hepatic tumors.METHODS Microspheres with different concentrations of 152SmAcAc(i.e.,100%,150%,175%and 200%w/w)were prepared by solvent evaporation method.The microspheres were then activated using a nuclear reactor in a Neutron flux of 2×10^12n/cm^2/s^1,converting 152Sm to Samarium-153(153)Sm)via 152Sm(n,γ) 153Sm reaction.The SmAcAc-PLLA microspheres before and after Neutron activation were characterized using scanning electron microscope,energy dispersive X-ray spectroscopy,particle size analysis,Fourier transform infrared spectroscopy,thermo-gravimetric analysis and gamma spectroscopy.The in-vitro radiolabeling efficiency was also tested in both 0.9% sodium chloride solution and human blood plasma over a duration of 550 h.RESULTS The SmAcAc-PLLA microspheres with different SmAcAc contents remained spherical before and after Neutron activation.The mean diameter of the microspheres was about 35μm.Specific activity achieved for 153SmAcAc-PLLA microspheres with 100%,150%,175%and 200%(w/w)SmAcAc after 3 h Neutron activation were 1.7±0.05,2.5±0.05,2.7±0.07,and 2.8±0.09 GBq/g,respectively.The activity of per microspheres were determined as 48.36±1.33,74.10±1.65,97.87±2.48,and 109.83±3.71 Bq for 153SmAcAc-PLLA microspheres with 100%,150%,175%and 200%(w/w)SmAcAc.The energy dispersive X-ray and gamma spectrometry showed that no elemental and radioactive impurities present in the microspheres after Neutron activation.Retention efficiency of 153Sm in the SmAcAc-PLLA microspheres was excellent(approximately 99%)in both 0.9%sodium chloride solution and human blood plasma over a duration of 550 h.CONCLUS

关键词： Radioembolization Samarium-153 Yittrium-90 Biodegradable microsphere Liver tumors Neutron activation

Effect of non-stationary accretion on spectral state transitions:An example of a persistent Neutron star LMXB 4U 1636–536

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Research in Astronomy and Astrophysics 2018年第3期18卷 91-98页

作者： Hui Zhang Wen-Fei Yu Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical ObservatoryChinese Academy of Sciences

Observations of black hole and Neutron star X-ray binaries show that the luminosity of the hard-to-soft state transition is usually higher than that of the soft-to-hard state transition,indicating additional parameters other than mass accretion rate are required to interpret spectral state transitions.It has been found in some individual black hole or Neutron star soft X-ray transients that the luminosity corresponding to the hard-to-soft state transition is positively correlated with the peak luminosity of the following soft state. In this work,we report the discovery of the same correlation in the single persistent Neutron star low mass X-ray binary（LMXB） 4 U 1636–536 based on data from the All Sky Monitor（ASM） on board RXTE,the Gas Slit Camera（GSC） on board MAXI and the Burst Alert Telescope（BAT） on board Swift. We also found such a positive correlation holds in this persistent Neutron star LMXB in a luminosity range spanning about a factor of four. Our results indicate that non-stationary accretion also plays an important role in driving X-ray spectral state transitions in persistent accreting systems with small accretion flares,which is much less dramatic compared with the bright outbursts seen in many Galactic LMXB transients.

关键词： accretion accretion disks - X-rays binaries - stars Neutron

Toward a fractal spectrum approach for Neutron and gamma pulse shape discrimination

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Chinese Physics C 2016年第6期40卷 67-73页

作者：刘明哲刘炳琦左卓王磊昝贵彬庹先国 State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology) Chengdu 610059China College of Nuclear Technology and Automation Engineering Chengdu University of TechnologyChengdu 610059China

Accurately selecting Neutron signals and discriminating γsignals from a mixed radiation field is a key research issue in Neutron detection. This paper proposes a fractal spectrum discrimination approach by means of different spectral characteristics of Neutrons and γ rays. Figure of merit and average discriminant error ratio are used together to evaluate the discrimination effects. Different Neutron and γ signals with various noise and pulse pile-up are simulated according to real data in the literature. The proposed approach is compared with the digital charge integration and pulse gradient methods. It is found that the fractal approach exhibits the best discrimination performance, followed by the digital charge integration method and the pulse gradient method, respectively. The fractal spectrum approach is not sensitive to high frequency noise and pulse pile-up. This means that the proposed approach has superior performance for effective and efficient anti-noise and high discrimination in Neutron detection.

关键词： Neutron γactal spectrum

Miniaturized time-of-flight Neutron spin flipper using a high-TC superconductor

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Nuclear Science and Techniques 2022年第11期33卷 113-119页

作者： Yu-Chen Dong Tian-Hao Wang Wolfgang Kreuzpaintner Xiao-Tao Liu Ze-Hui Li Yu-Dong Kang Jun-Pei Zhang Long Tian Chu-Yi Huang Bo Bai Xin Tong Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523803China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Guangzhou Institute of Technology Xidian UniversityGuangzhou 510555China

A miniaturized Neutron spin flipper based on a high-TC superconductor film,developed at the China Spallation Neutron Source(CSNS),is presented.A Neutron spin flipper is an essential component for performing polarized Neutron experiments and,as such,constitutes a high priority for developing CSNS’s polarized Neutron capability.To provide the beamlines with a universal Neutron spin flipper operating over a wide wavelength band,the Neutron spin flipper utilizes non-adiabatic spin flipping during transit through opposite magnetic fields that are mutually shielded by the superconductor Meissner effect.A compact vacuum heat shield and a low-power consumption sterling refrigerator maintained the superconducting condition while reducing the size and power input of the flipper.The prototype device was tested at the CSNS BL-20,which demonstrated a flipping efficiency of 99%at 4 A°.

关键词： Neutron Superconductor Scattering Spinflipper

Impact of incident direction on Neutron-induced single-bit and multiple-cell upsets in 14 nm FinFET and 65 nm planar SRAMs

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Chinese Physics B 2022年第12期31卷 375-381页

作者：杨少华张战刚雷志锋黄云习凯王松林梁天骄童腾李晓辉彭超吴福根李斌 School of Physics and Optoeletronic Engineering Guangdong University of TechnologyGuangzhou 510006China Science and Technology on Reliability Physics and Application of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research InstituteGuangzhou 510370China Institute of Microelectronics of Chinese Academy of Sciences Beijing 100029China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523803China School of Microelectronics South China University of TechnologyGuangzhou 510640China

Based on the BL09 terminal of China Spallation Neutron Source(CSNS),single event upset(SEU)cross sections of14 nm fin field-effect transistor(FinFET)and 65 nm quad data rate(QDR)static random-access memories(SRAMs)are obtained under different incident directions of Neutrons:front,back and side.It is found that,for both technology nodes,the“worst direction”corresponds to the case that Neutrons traverse package and metallization before reaching the sensitive volume.The SEU cross section under the worst direction is 1.7-4.7 times higher than those under other incident directions.While for multiple-cell upset(MCU)sensitivity,side incidence is the worst direction,with the highest MCU ratio.The largest MCU for the 14 nm FinFET SRAM involves 8 bits.Monte-Carlo simulations are further performed to reveal the characteristics of Neutron induced secondary ions and understand the inner mechanisms.

关键词： Neutron fin field-effect transistor(FinFET) single event upset(SEU) Monte-Carlo simulation

Pre-Neutron-emission Mass Distributions for Reaction ^(232)Th(n,f) up to 60 MeV

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Communications in Theoretical Physics 2014年第11期61卷 711-716页

作者：孙小军潘成华余呈刚杨永栩王宁 Department of Physics Guangxi Normal University Shanghai Institute of Applied Physics Chinese Academy of Sciences

The pre-Neutron-emission mass distributions for reaction232Th(n, f) up to 60 MeV are systematically studied with an empirical fission potential model. The energy dependences of the peaks and valleys of the pre-Neutronemission mass distributions are described by the exponential expressions based on the newly measured data. The energy dependence of evaporation Neutrons before scission, which plays a crucial role for the reasonable description of the mass distribution, is also considered. Both the double-humped and triple-humped shape of the measured pre-Neutronemission mass distributions for reaction232Th(n, f) are reasonably well reproduced at incident energies up to 60 MeV.The mass distributions at unmeasured energies and the critical energies at which the humped pre-Neutron-emission mass distributions are transformed into each other are also predicted.

关键词： 232Th(n f) pre-Neutron-emission mass distribution evaporation Neutron fission potential