While developing nuclear materials,predicting their behavior under long-term irradiation regimes span-ning decades poses a significant challenge.We developed a novel Kinetic Monte Carlo(KMC)model to explore the precip...While developing nuclear materials,predicting their behavior under long-term irradiation regimes span-ning decades poses a significant challenge.We developed a novel Kinetic Monte Carlo(KMC)model to explore the precipitation behavior of Y-Ti-O oxides along grain boundaries within nanostructured ferritic alloys(NFA).This model also assessed the response of the oxides to neutron irradiation,even up sim-ulated radiation damage levels in the desired long dpa range for reactor components.Our simulations investigated how temperature and grain boundary sinks influenced the oxide characteristics of a 12YWT-like alloy during heat treatments at 1023,1123,and 1223 K.The oxide characteristics observed in our simulations were in good agreement with existing literature.Furthermore,the impact of grain bound-aries on precipitation was found to be minimal.The resulting oxide configurations and positions were used in subsequent simulations that exposed them to simulated neutron irradiation to a total accumu-lated dose of 8 dpa at three temperatures:673,773,and 873 K,and at dose rates of 10-3,10-4,and 10-5 dpa/s.This demonstrated the expected inverse relationship between oxide size and dose rate.In a long-term irradiation simulation at 873 K and 10-3 dpa/s was taken out to 66 dpa and found the oxides in the vicinity of the grain boundary were more susceptible to dissolution.Additionally,we conducted irradia-tion simulations of a 14YWT-like alloy to reproduce findings from neutron irradiation experiments.The larger oxides in the 14YWT-like alloy did not dissolve and displayed stability similar to the experimental results.展开更多
This work presents a systematic analysis of proton-induced total ionizing dose(TID)effects in 1.2 k V silicon carbide(SiC)power devices with various edge termination structures.Three edge terminations including ring-a...This work presents a systematic analysis of proton-induced total ionizing dose(TID)effects in 1.2 k V silicon carbide(SiC)power devices with various edge termination structures.Three edge terminations including ring-assisted junction termination extension(RA-JTE),multiple floating zone JTE(MFZ-JTE),and field limiting rings(FLR)were fabricated and irradiated with45 Me V protons at fluences ranging from 1×10^(12) to 1×10^(14) cm^(-2).Experimental results,supported by TCAD simulations,show that the RA-JTE structure maintained stable breakdown performance with less than 1%variation due to its effective electric field redistribution by multiple P+rings.In contrast,MFZ-JTE and FLR exhibit breakdown voltage shifts of 6.1%and 15.2%,respectively,under the highest fluence.These results demonstrate the superior radiation tolerance of the RA-JTE structure under TID conditions and provide practical design guidance for radiation-hardened Si C power devices in space and other highradiation environments.展开更多
The micro-beam irradiation system,which focuses the beam down to micron order and precisely delivers a predefined number of ions to a predefined spot of micron order,is a powerful tool for radio-biology,radio-biomedic...The micro-beam irradiation system,which focuses the beam down to micron order and precisely delivers a predefined number of ions to a predefined spot of micron order,is a powerful tool for radio-biology,radio-biomedicine and micromachining.The Institute of Modern Physics of Chinese Academy of Sciences is developing a heavy-ion micro- beam irradiation system up to intermediate energy.Based on the intermediate and low energy beam provided by Heavy Ion Research Facility of Lanzhou,the micro-beam system takes the form of the magnetic focusing.The heavy-ion beam is conducted to the basement by a symmetrical achromatic system consisting of two vertical bending magnets and a quadrupole in between.Then a beam spot of micron order is formed by a magnetic triplet quadrupole of very high gradient.The sample can be irradiated either in vacuum or in the air.This system will be the first opening platform capable of providing heavy ion micro-beam,ranging from low(10MeV/u)to intermediate energy(100MeV/u), for irradiation experiment with positioning and counting accuracy.Target material may be biology cell,tissue or other non-biological materials.It will be a help for unveiling the essence of heavy-ion interaction with matter and also a new means for exploring the application of heavy-ion irradiation.展开更多
The response of the antioxidant defense system of an intertidal macroalgae Corallina officinalis L.to different dosages of UV-B irradiation was investigated.Results showed that superoxide dimutase （SOD） and peroxida...The response of the antioxidant defense system of an intertidal macroalgae Corallina officinalis L.to different dosages of UV-B irradiation was investigated.Results showed that superoxide dimutase （SOD） and peroxidase （POX） increased and then maintained at a relatively stable level when subjected to UV-B irradiation.Catalase （CAT） activity under medium dosage of UV-B irradiation （Muv） and high dosage of UV-B irradiation （Huv） treatments were significantly decreased.Ascorbate peroxidase （APX） activity first remained unaltered and then increased in Huv treatment.In addition,the assay on isozymes was carried out using non-denaturing polyacrylamide gel electrophoresis （PAGE）.The activities of some SOD isoforms were altered by UV-B.Two new bands （POX V and POX VII） appeared upon exposure to all three UV-B dosages.CAT III activity was increased by low dosage of UV-B irradiation （Luv）,whereas CAT III and CAT IV disappeared when the alga was exposed to Muv and Huv.Two bands of APX （APX VI and APX VII） were increased and a new band （APX X） was observed under Huv exposure.H 2 O 2 and thiobarbituric acid reacting substance （TBARS） increased under Muv and Huv treatments.Overall,UV-B protection mechanisms are partly inducible and to a certain extent sufficient to prevent the accumulation of damage in C.officinalis.展开更多
This study aims to produce 229Th using an innovative nuclear reactor concept,i.e.,accelerator-driven system(ADS)reactor.Herein,we investigated the feasibility of producing 229Th from neutron transmutation of 226Ra to ...This study aims to produce 229Th using an innovative nuclear reactor concept,i.e.,accelerator-driven system(ADS)reactor.Herein,we investigated the feasibility of producing 229Th from neutron transmutation of 226Ra to expand the availability of 225Ac and 213Bi in a simple model of ADS reactor.ADS reactor comprises two zones,i.e.,an inner zone with a fast neutron spectrum and outer zone with thermal neutron spectrum,which is a subcritical core coupled with an external neutron source.Transmutation behavior,activity,and mass ratio of the obtained isotopes were investigated using the Monte-Carlo tool.In addition with offering the capability,flexibility,and safety of radioactive waste transmutation,the proposed ADS model provides high 229Th yield and requires less time than a critical reactor with the same neutron flux and irradiated quantity of 226Ra.展开更多
For the immiscible Mo/Cu system with a positive heat of mixing （△Hm 〉 0）, building metallurgical bonding interfaces directly between immiscible Mo and Cu and preparing Mo/Cu laminar metal matrix composites （LMMCs...For the immiscible Mo/Cu system with a positive heat of mixing （△Hm 〉 0）, building metallurgical bonding interfaces directly between immiscible Mo and Cu and preparing Mo/Cu laminar metal matrix composites （LMMCs） are very difficult. To solve the problem, a new alloying method for immiscible systems, which is named as irradiation damage alloying （IDA）, is presented in this paper. The IDA primarily consists of three steps. Firstly, Mo is damaged by irradiation with multi-energy （186, 62 keV） Cu ion beams at a dose of 2× 1017 ions/cm2. Secondly, Cu layers are superimposed on the surfaces of the irradiation-damaged Mo to obtain Mo]Cu laminated specimens. Thirdly, the irradiation damage induces the diffusion alloying between Mo and Cu when the laminated specimens are annealed at 950 ℃ in a protective atmosphere. Through IDA, Mo/Cu LMMCs are prepared in this paper. The tensile tests carried out for the Mo/Cu LMMCs specimens show that the Mo/Cu interfaces constructed via IDA have high normal and shear strengths. Additionally, the microstructure of the Mo/Cu interface is characterized by High Resolution Transmission Electron Microscopy （HRTEM）, X-ray diffraction （XRD） and Energy Dispersive X-ray （EDX） attached in HRTEM. The microscopic characterization results show that the expectant diffusion between Mo and Cu occurs through the irradiation damage during the process of IDA. Thus a Mo/Cu metallurgical bonding interface successfully forms. Moreover, the microscopic test results show that the Mo/Cu metallurgical interface is mainly constituted of crystalline phases with twisted and tangled lattices, and amorphous phase is not observed. Finally, based on the positron annihilation spectroscopy （PAS） and HRTEM results, the diffusion mechanism of IDA is discussed and determined to be vacancy assisted diffusion.展开更多
The effects of annealing and irradiation on the evolution of Cu clusters in a-Fe are investigated using object kinetic Monte Carlo simulations.In our model,vacancies act as carriers for chemical species via thermally ...The effects of annealing and irradiation on the evolution of Cu clusters in a-Fe are investigated using object kinetic Monte Carlo simulations.In our model,vacancies act as carriers for chemical species via thermally activated diffusion jumps,thus playing an important role in solute diffusion.At the end of the Cu cluster evolution,the simulations of the average radius and number density of the clusters are consistent with the experimental data,which indicates that the proposed simulation model is applicable and effective.For the simulation of the annealing process,it is found that the evolution of the cluster size roughly follows the 1/2 time power law with the increase in radius during the growth phase and the 1/3 time power law during the coarsening phase.In addition,the main difference between neutron and ion irradiation is the growth and evolution process of the copper-vacancy clusters.The aggregation of vacancy clusters under ion irradiation suppresses the migration and coarsening of the clusters,which ultimately leads to a smaller average radius of the copper clusters.Our proposed simulation model can supplement experimental analyses and provide a detailed evolution mechanism of vacancy-enhanced precipitation,thereby providing a foundation for other elemental precipitation research.展开更多
To shed a light on Xe bubble nucleation in U–Mo fuel from the view of primary irradiation damage,a reported U–Mo–Xe potential under the framework of embedded atom method has been modified within the range of short ...To shed a light on Xe bubble nucleation in U–Mo fuel from the view of primary irradiation damage,a reported U–Mo–Xe potential under the framework of embedded atom method has been modified within the range of short and intermediate atomic distance.The modified potential can better describe the interactions between energetic particles,and can accurately reproduce the threshold displacement energy surface calculated by the first-principles method.Then,molecular dynamics simulations of primary irradiation damage in U–Mo–Xe system have been conducted under different contents.The raise of Xe concentration brings about a remarkable promotion in residual defect quantity and generates bubbles in more overpressured state,which suggests an acceleration of irradiation damage under the accumulation of the fission gas.Meanwhile,the addition of Mo considerably reduces the residual defect count and hinders irradiation-induced Xe diffusion especially at high contents of Xe,corroborating the importance of high Mo content in mitigation of irradiation damage and swelling behavior in U–Mo fuel.In particular,the variation of irradiation damage with respect to contents suggests a necessity of taking into account the influence of local components on defect evolution in mesoscale simulations.展开更多
AIM:To evaluate whether anterior cruciate ligament(ACL) allograft irradiation is effective for sterility without compromising graft integrity and increasing failure rate.METHODS:A literature search was conducted using...AIM:To evaluate whether anterior cruciate ligament(ACL) allograft irradiation is effective for sterility without compromising graft integrity and increasing failure rate.METHODS:A literature search was conducted using Pub Med,Cochrane,and Google.The following search terms were used:"Gamma irradiation AND anterior cruciate ligament AND allograft" with a return of 30 items.Filters used included:English language,years 1990-2015.There were 6 hits that were not reviewed,as there were only abstracts available.Another 5 hits were discarded,as they did not pertain to the topic of interest.There were 9 more articles that were excluded:Three studies were performed on animals and 6 studies were meta-analyses.Therefore,a total of 10 articles were applicable to review.RESULTS:There is a delicate dosing crossover where gamma irradiation is both effective for sterility without catastrophically compromising the structural integrity of the graft.Of note,low dose irradiation is considered less than 2.0 Mrad,moderate dose is between 2.1-2.4 Mrad,and high dose is greater than or equal to 2.5 Mrad.Based upon the results of the literature search,the optimal threshold for sterilization was found to be sterilization at less than 2.2 Mrad of gamma irradiation with the important caveat of being performed at low temperatures.The graft selection process also must include thorough donor screening and testing as well as harvesting the tissue in a sterile fashion.Utilization of higher dose(≥ 2.5 Mrad) of irradiation causes greater allograft tissue laxity that results in greater graft failure rate clinically in patients after ACL reconstruction.CONCLUSION:Allograft ACL graft gamma irradiatedwith less than 2.2 Mrad appears to be a reasonable alternative to autograft for patients above 25 years of age.展开更多
A green and convenient approach for the synthesis of a series of 5,5'-(arylmethylene)bis(4-hydroxythiazole-2(3H)-one)by the reaction of aryl aldehydes,monochloroacetic acid and ammonium thiocyanate in water/triflu...A green and convenient approach for the synthesis of a series of 5,5'-(arylmethylene)bis(4-hydroxythiazole-2(3H)-one)by the reaction of aryl aldehydes,monochloroacetic acid and ammonium thiocyanate in water/trifluoroethanol(TFE)(1:1)under ultrasound irradiation at room temperature is described.This method provides several advantages such as environmental friendliness,shorter time,excellent yields,and simple work-up procedure.展开更多
Objective： The aim of the research was to study the effects of low-dose splenic irradiation and radiotherapy on immune system of patients with locally advanced non-small cell lung cancer （NSCLC）. Methods： Twelve c...Objective： The aim of the research was to study the effects of low-dose splenic irradiation and radiotherapy on immune system of patients with locally advanced non-small cell lung cancer （NSCLC）. Methods： Twelve cases of stage III NSCLC in Tumor Radiotherapy Center of our hospital （the Affiliated Hospital of Medical College Qingdao University, China） were collected from July 2011 to July 2012; all patients were under 75 years old with clear pathology, measurable lesions and good personal statement. They were randomly divided into combined treatment group （D1 ＋ D2） and control group （D1）. The control group （D1） only received radiotherapy to the chest; combined treatment group （D1 ＋ D2） received low-dose splenic irradiation plus conventional dose irradiation. Flow cytometry was used to detect the peripheral blood T lymphocyte immune indexes of patients before, during and after the treatment, classification by five blood cell analyzer was used to determine white blood cells, neutrophils, hemoglobin and platelet count. The radiation induced toxicity including esophagitis, pneumonia and gastrointestinal reaction was observed, as well as the dose when it happened. Results： There was no significant difference in the ratio between two groups in cells CD4＋, CD8＋ and CD4＋/CD8＋ after radiotherapy （P 〉 0.05）. There was no change in these indicators in combined treatment group after treatment （P 〉 0.05）, but it decreased in control group （P 〈 0.05）. There was no significant difference in the incidences of radiation esophagitis, pneumonia, gastrointestinal reactions and bone marrow suppression between two groups （P 〉 0.05）, but the patients in combined treatment group seemed to tolerate high dose well （P 〈 0.05）. Conclusion： Low-dose splenic irradiation combined with radiotherapy to the chest can alleviate the injury degree of acute radiation induced the toxicity of locally advanced NSCLC patients, through affect the patient＇s immune function.展开更多
Around the world, radioactive sources have been widely used for decades to benefit humankind; industry food; health, etc. However, the malicious use of radiological sources poses a significant threat globally. As Irra...Around the world, radioactive sources have been widely used for decades to benefit humankind; industry food; health, etc. However, the malicious use of radiological sources poses a significant threat globally. As Irradiation facility for research the goal of this paper is to show a case study of application of nuclear security and nuclear security culture code of contact in irradiation facility using cobalt 60. And it will show the necessary work done to achieve the goal of protection of radioactive material and continue working in safe conditions. This objective could not be achieved without the collaboration of all department involved in security and nuclear safety. In this work we applied the nuclear security and nuclear security culture procedures in order to define the type of system used to achieve the global objective in accordance with Global Threat Reduction Program to reduce the threat of a RDD （Radiological Dispersion Device） in collaboration with The United States Department of Energy＇s NNSA （National Nuclear Security Administration）. The objective of this paper is to share a local experience in upgrading security with return of experience in practice and very good collaboration with general direction of national security and all departments involved in security and nuclear safety.展开更多
This paper is devoted to the study of the potentiality of the Fricke dosimeter for the characterization of the highly energetic (62.1 MeV) α particles beams generated by a new cyclotron facility, namely ARRONAX start...This paper is devoted to the study of the potentiality of the Fricke dosimeter for the characterization of the highly energetic (62.1 MeV) α particles beams generated by a new cyclotron facility, namely ARRONAX started in 2009. Such for this high energetic α beam, in situ dosimetry is performed in order to avoid radiation safety inconvenience and to earn run time of irradiation. Therefore, an in situ Fricke dosimetry protocol is developed and its reliability is checked by comparison with other experiments carried out by using the traditional method (ex situ Fricke dosimetry) within another cyclotron facility (CEMHTI) and by comparison with literature data. To author’s knowledge, it is the first time that Fricke dosimetry is performed during the α irradiation experiment. The results of these in situ dosimetry experiments show that the value of ferric ions radiolytic yield (G(Fe3+) = (11.7 ± 1.2) 10–7 mol?J–1) extrapolated from literature data can be used for this higher energy of α particles (Eα = 62.1 MeV).展开更多
Solar energy is the raw material and main source for several applications of renewable energy systems;thus, knowledge about the intensity of solar irradiation is essential for efficiency of these systems. Electric ene...Solar energy is the raw material and main source for several applications of renewable energy systems;thus, knowledge about the intensity of solar irradiation is essential for efficiency of these systems. Electric energy sources capable of meeting the growing demands of society with minimal impacts to the environment and high efficiency have been object of research in the last decade. In this context, the conversion of sunlight into electricity through photovoltaic cells has become one of the most encouraged and used resources in the world. However, the most unpredictable factor, which hampers capturing solar irradiation, preventing a proper conversion of sunlight into electricity, is the presence of clouds in the sky. Many methods of tracking and prediction of irradiation were proposed to increase efficiency in the production of energy by photovoltaic cells. This article presents an updated review on the mechanisms used for tracking and irradiation prediction, and their respective methods. It begins with a brief review on photovoltaic systems and classification of its mechanisms. Then, it presents a detailed overview on the evolution of mechanisms and their corresponding methods for tracking and irradiation prediction. Finally, the authors conclude with an analysis of performance efficiency of the mechanisms and their corresponding methods presented, describing the pros and cons of the most significant proposals for tracking and irradiation prediction.展开更多
Arabidopsis thaliana is one of the most commonly used model plants due to its short life cycle and concise genome.As a novel physical mutagen, heavy ion beams have been widely used in plant breeding. The most signific...Arabidopsis thaliana is one of the most commonly used model plants due to its short life cycle and concise genome.As a novel physical mutagen, heavy ion beams have been widely used in plant breeding. The most significant advantages of heavy ion beams are the higher linear energy transfer (LET) and relative biological effectiveness (RBE), inducing a broad spectrum of mutation phenotypes even at low irradiation[1]. In order to investigate the effects on DNA behavior of Arabidopsis thaliana mutants induced by carbon ion irradiations, inter-simple sequence repeat (ISSR), a DNA-based molecular marker technique, was performed to assess the genetic polymorphism.展开更多
The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by deposit...The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by depositing Pt and RuO_(2)particles onto g-C_(3)N_(4).The physicochemical properties of photocatalysts were explored by X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),X-ray diffraction(XRD),and UV–vis diffuse reflectance spectrometer(UV–vis DRS).The photocatalysts were then applied to the removal of both NH_(4)^(+)-N and bacteria from simulated mariculture wastewater.The results clarified that the removals of both NH_(4)^(+)-N and bacteria were in the sequence of g-C_(3)N_(4)<RuO_(2)/g-C_(3)N_(4)<Pt/g-C_(3)N_(4)<Pt/RuO_(2)/g-C_(3)N_(4).This magnificent photocatalytic ability of Pt/RuO_(2)/g-C_(3)N_(4)can be interpreted by the transfer of holes from g-C_(3)N_(4)to RuO_(2)to facilitate the in situ generation of HClO from Cl^(−)in wastewater,while Pt extracts photogenerated electrons for H_(2)formation to enhance the reaction.The removal of NH_(4)^(+)-N and disinfection effect were more pronounced in simulated seawater than in purewater.The removal efficiency ofNH_(4)^(+)-N increases with an increase in pH of wastewater,while the bactericidal effect was more significant under a lower pH in a pH range of 6–9.In actual seawater aquaculture wastewater,Pt/RuO_(2)/g-C_(3)N_(4)still exhibits effective removal efficiency of NH_(4)^(+)-N and bactericidal performance under sunlight.This study provides an alternative avenue for removement of NH_(4)^(+)-N and bacteria from saline waters under sunlight.展开更多
The Mg alloys with combination of high strength and excellent irradiation resistance are currently re-quired for research reactors.In this work,the novel Mg-3Mn-0.5Ca alloy with a high strength of over 300 MPa has bee...The Mg alloys with combination of high strength and excellent irradiation resistance are currently re-quired for research reactors.In this work,the novel Mg-3Mn-0.5Ca alloy with a high strength of over 300 MPa has been fabricated via co-addition of Mn and Ca elements.Moreover,the Xe ion implantation(300℃/4.5×10^(15)ions/cm^(2))is conducted for pure Mg,Mg-3Mn and Mg-3Mn-0.5Ca alloys.Microstruc-ture characterization shows that the number density of dislocation loops is comparable between Mg-3Mn and pure Mg,while the phase boundary of nano-Mn particles could act as the sink to absorb more Xe atoms,resulting in the abundant formation of Xe bubbles in the matrix of irradiated Mg-3Mn alloy.With further minor addition of Ca element,the formation of Xe bubbles and dislocation loops in Mg-3Mn-0.5Ca alloy has been obviously suppressed,and the abundant grain boundaries(GBs)due to grain refinement then act as the sink region for Xe precipitation.The limited number density of Xe bubbles leads to the extremely low swelling ratio in Mg-3Mn-0.5Ca alloy,∼0.08%.The result above suggests that the Mn and Ca co-addition could enhance the mechanical properties and irradiation tolerance of Mg alloys,si-multaneously.The present low-alloying strategy would provide a new design reference for novel nuclear materials.展开更多
UV irradiation hydrogen peroxide （H202） system is used as an effective, easy and low-cost combined depolymerization technique to produce oligosaccharides from chitosan. UV-Vis spectroscopic studies explained that wi...UV irradiation hydrogen peroxide （H202） system is used as an effective, easy and low-cost combined depolymerization technique to produce oligosaccharides from chitosan. UV-Vis spectroscopic studies explained that with increasing treatment time, the absorption of the depolymerized chitosan solution has increased, indicating the increase in the carbonyl and amino groups in their structure. Fourier transform infrared spectroscopy and nuclear magnetic resonance （1H NMR） analysis showed that the 1,4-β-D-glucoside linkages of chitosan are degraded without important changes in chemical structure of decomposed samples. X-ray diffraction patterns verified the polymerization of chitosan to produce oligomers, changing in structure from crystalline to amorphous. Viscosity-average molecular weight measurements of fragmented chitosan samples and MarkHouwink equation are used to demonstrate the efficiency of this depolymerization method. Finally, the obtained results ascertained that this combined method could produce water soluble chitosan with significant efficiency and no essential change in its chemical structure.UV irradiation hydrogen peroxide （H202） system is used as an effective, easy and low-cost combined depolymerization technique to produce oligosaccharides from chitosan. UV-Vis spectroscopic studies explained that with increasing treatment time, the absorption of the depolymerized chitosan solution has increased, indicating the increase in the carbonyl and amino groups in their structure. Fourier transform infrared spectroscopy and nuclear magnetic resonance （1H NMR） analysis showed that the 1,4-β-D-glucoside linkages of chitosan are degraded without important changes in chemical structure of decomposed samples. X-ray diffraction patterns verified the polymerization of chitosan to produce oligomers, changing in structure from crystalline to amorphous. Viscosity-average molecular weight measurements of fragmented chitosan samples and MarkHouwink equation are used to demonstrate the efficiency of this depolymerization method. Finally, the obtained results ascertained that this combined method could produce water soluble chitosan with significant efficiency and no essential change in its chemical structure.展开更多
On the surfaces of celestial bodies with no or thin atmospheres,such as the Moon and Mars,the solar wind irradiation process leads to the formation of hydrogen and helium enriched regions in the extraterrestrial soil ...On the surfaces of celestial bodies with no or thin atmospheres,such as the Moon and Mars,the solar wind irradiation process leads to the formation of hydrogen and helium enriched regions in the extraterrestrial soil particles.However,soil particles on the Earth with the similar composition lack such structures and properties.This discrepancy raises a key question whether there is a direct relationship between solar wind irradiation and the alterations in the structure and chemical performance of extraterrestrial materials.To address this question,this work investigates the effects of proton irradiation,simulating solar wind radiation,on the structure and photothermal catalytic properties of the classic catalyst In_(2)O_(3).It reveals that proton irradiation induces structural features in In_(2)O_(3) analogous to those characteristics of solar wind weathering observed in extraterrestrial materials.Furthermore,after proton beam irradiation with an energy of 30 keV and a dose of 3×10^(17) protons·cm^(-2),the methanol production yield of the In_(2)O_(3) catalyst increased to 2.6 times of its preirradiation level,and the methanol selectivity improved to 2.1 times of the original value.This work provides both theoretical and experimental support for the development of high-efficiency,radiation-resistant photothermal catalysts.展开更多
High-entropy alloys(HEAs)exhibit the excellent elevated-temperature performance and irradiation resistance due to the important core effect of serious lattice distortion for impeding dislocation motion,as candidate ma...High-entropy alloys(HEAs)exhibit the excellent elevated-temperature performance and irradiation resistance due to the important core effect of serious lattice distortion for impeding dislocation motion,as candidate materials for nuclear applications.Despite the growth of the nuclear power sector,the effects of high-temperature and high-dose irradiation-induced voids on the mechanical properties of HEA in higher power nuclear reactors remain insufficiently researched,hindering its industrial application.In this study,we establish a consistent parameterization crystal plastic constitutive model for the hardening and creep behaviors of HEA,incorporating the spatial distribution of void size and shape effects,in contrast to traditional creep models that rely on temperature-related fitting parameters of the phenomenological power law equation.The model matches well with experimental data at different temperatures and irradiation doses,demonstrating its robustness.The effects of irradiation dose,temperature,and degree of lattice distortion on irradiation hardening and creep behavior of void-containing HEA are investigated.The results indicate that HEA with high lattice distortion exhibits better creep resistance under higher stress loads.The yield stress of irradiated HEA increases with increasing irradiation dose and temperature.The creep resistance increases with increasing irradiation dose and decreases with increasing irradiation temperature.The increase in irradiation dose causes a specific morphological transformation from spherical to cubic voids.The modeling and results could provide an effective theoretical way for tuning the yield strength and alloy design in advanced HEAs to meet irradiation properties.展开更多
基金supported by the Nuclear Regulatory Commission Fellowship Grant No.NRC-HQ-84-14-G-0035.
文摘While developing nuclear materials,predicting their behavior under long-term irradiation regimes span-ning decades poses a significant challenge.We developed a novel Kinetic Monte Carlo(KMC)model to explore the precipitation behavior of Y-Ti-O oxides along grain boundaries within nanostructured ferritic alloys(NFA).This model also assessed the response of the oxides to neutron irradiation,even up sim-ulated radiation damage levels in the desired long dpa range for reactor components.Our simulations investigated how temperature and grain boundary sinks influenced the oxide characteristics of a 12YWT-like alloy during heat treatments at 1023,1123,and 1223 K.The oxide characteristics observed in our simulations were in good agreement with existing literature.Furthermore,the impact of grain bound-aries on precipitation was found to be minimal.The resulting oxide configurations and positions were used in subsequent simulations that exposed them to simulated neutron irradiation to a total accumu-lated dose of 8 dpa at three temperatures:673,773,and 873 K,and at dose rates of 10-3,10-4,and 10-5 dpa/s.This demonstrated the expected inverse relationship between oxide size and dose rate.In a long-term irradiation simulation at 873 K and 10-3 dpa/s was taken out to 66 dpa and found the oxides in the vicinity of the grain boundary were more susceptible to dissolution.Additionally,we conducted irradia-tion simulations of a 14YWT-like alloy to reproduce findings from neutron irradiation experiments.The larger oxides in the 14YWT-like alloy did not dissolve and displayed stability similar to the experimental results.
基金supported by the IITP(Institute for Information&Communications Technology Planning&Evaluation)under the ITRC(Information Technology Research Center)support program(IITP-2025-RS-2024-00438288)grant funded by the Korea government(MSIT)+1 种基金National Research Council of Science&Technology(NST)grant by the MSIT(Aerospace Semiconductor Strategy Research Project No.GTL25051-000)supported by the IC Design Education Center(IDEC),Korea。
文摘This work presents a systematic analysis of proton-induced total ionizing dose(TID)effects in 1.2 k V silicon carbide(SiC)power devices with various edge termination structures.Three edge terminations including ring-assisted junction termination extension(RA-JTE),multiple floating zone JTE(MFZ-JTE),and field limiting rings(FLR)were fabricated and irradiated with45 Me V protons at fluences ranging from 1×10^(12) to 1×10^(14) cm^(-2).Experimental results,supported by TCAD simulations,show that the RA-JTE structure maintained stable breakdown performance with less than 1%variation due to its effective electric field redistribution by multiple P+rings.In contrast,MFZ-JTE and FLR exhibit breakdown voltage shifts of 6.1%and 15.2%,respectively,under the highest fluence.These results demonstrate the superior radiation tolerance of the RA-JTE structure under TID conditions and provide practical design guidance for radiation-hardened Si C power devices in space and other highradiation environments.
文摘The micro-beam irradiation system,which focuses the beam down to micron order and precisely delivers a predefined number of ions to a predefined spot of micron order,is a powerful tool for radio-biology,radio-biomedicine and micromachining.The Institute of Modern Physics of Chinese Academy of Sciences is developing a heavy-ion micro- beam irradiation system up to intermediate energy.Based on the intermediate and low energy beam provided by Heavy Ion Research Facility of Lanzhou,the micro-beam system takes the form of the magnetic focusing.The heavy-ion beam is conducted to the basement by a symmetrical achromatic system consisting of two vertical bending magnets and a quadrupole in between.Then a beam spot of micron order is formed by a magnetic triplet quadrupole of very high gradient.The sample can be irradiated either in vacuum or in the air.This system will be the first opening platform capable of providing heavy ion micro-beam,ranging from low(10MeV/u)to intermediate energy(100MeV/u), for irradiation experiment with positioning and counting accuracy.Target material may be biology cell,tissue or other non-biological materials.It will be a help for unveiling the essence of heavy-ion interaction with matter and also a new means for exploring the application of heavy-ion irradiation.
基金supported by the National Natural Science Foundation of China (No. 30270258)the Natural Science Foundation of Shandong Province (No.2007ZRB01903)
文摘The response of the antioxidant defense system of an intertidal macroalgae Corallina officinalis L.to different dosages of UV-B irradiation was investigated.Results showed that superoxide dimutase （SOD） and peroxidase （POX） increased and then maintained at a relatively stable level when subjected to UV-B irradiation.Catalase （CAT） activity under medium dosage of UV-B irradiation （Muv） and high dosage of UV-B irradiation （Huv） treatments were significantly decreased.Ascorbate peroxidase （APX） activity first remained unaltered and then increased in Huv treatment.In addition,the assay on isozymes was carried out using non-denaturing polyacrylamide gel electrophoresis （PAGE）.The activities of some SOD isoforms were altered by UV-B.Two new bands （POX V and POX VII） appeared upon exposure to all three UV-B dosages.CAT III activity was increased by low dosage of UV-B irradiation （Luv）,whereas CAT III and CAT IV disappeared when the alga was exposed to Muv and Huv.Two bands of APX （APX VI and APX VII） were increased and a new band （APX X） was observed under Huv exposure.H 2 O 2 and thiobarbituric acid reacting substance （TBARS） increased under Muv and Huv treatments.Overall,UV-B protection mechanisms are partly inducible and to a certain extent sufficient to prevent the accumulation of damage in C.officinalis.
基金supported by the International Center for Theoretical Physics and the Institute of International Education’s Scholar Rescue Fund.
文摘This study aims to produce 229Th using an innovative nuclear reactor concept,i.e.,accelerator-driven system(ADS)reactor.Herein,we investigated the feasibility of producing 229Th from neutron transmutation of 226Ra to expand the availability of 225Ac and 213Bi in a simple model of ADS reactor.ADS reactor comprises two zones,i.e.,an inner zone with a fast neutron spectrum and outer zone with thermal neutron spectrum,which is a subcritical core coupled with an external neutron source.Transmutation behavior,activity,and mass ratio of the obtained isotopes were investigated using the Monte-Carlo tool.In addition with offering the capability,flexibility,and safety of radioactive waste transmutation,the proposed ADS model provides high 229Th yield and requires less time than a critical reactor with the same neutron flux and irradiated quantity of 226Ra.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51171128 and 51471114)the Key Technologies R & D Program of Tianjin (Grant No. 11ZCKFGX03800)
文摘For the immiscible Mo/Cu system with a positive heat of mixing （△Hm 〉 0）, building metallurgical bonding interfaces directly between immiscible Mo and Cu and preparing Mo/Cu laminar metal matrix composites （LMMCs） are very difficult. To solve the problem, a new alloying method for immiscible systems, which is named as irradiation damage alloying （IDA）, is presented in this paper. The IDA primarily consists of three steps. Firstly, Mo is damaged by irradiation with multi-energy （186, 62 keV） Cu ion beams at a dose of 2× 1017 ions/cm2. Secondly, Cu layers are superimposed on the surfaces of the irradiation-damaged Mo to obtain Mo]Cu laminated specimens. Thirdly, the irradiation damage induces the diffusion alloying between Mo and Cu when the laminated specimens are annealed at 950 ℃ in a protective atmosphere. Through IDA, Mo/Cu LMMCs are prepared in this paper. The tensile tests carried out for the Mo/Cu LMMCs specimens show that the Mo/Cu interfaces constructed via IDA have high normal and shear strengths. Additionally, the microstructure of the Mo/Cu interface is characterized by High Resolution Transmission Electron Microscopy （HRTEM）, X-ray diffraction （XRD） and Energy Dispersive X-ray （EDX） attached in HRTEM. The microscopic characterization results show that the expectant diffusion between Mo and Cu occurs through the irradiation damage during the process of IDA. Thus a Mo/Cu metallurgical bonding interface successfully forms. Moreover, the microscopic test results show that the Mo/Cu metallurgical interface is mainly constituted of crystalline phases with twisted and tangled lattices, and amorphous phase is not observed. Finally, based on the positron annihilation spectroscopy （PAS） and HRTEM results, the diffusion mechanism of IDA is discussed and determined to be vacancy assisted diffusion.
基金supported by the National Natural Science Foundation of China (Nos.11975135 and 12005017)China Postdoctoral Science Foundation (No.2021M701829)
文摘The effects of annealing and irradiation on the evolution of Cu clusters in a-Fe are investigated using object kinetic Monte Carlo simulations.In our model,vacancies act as carriers for chemical species via thermally activated diffusion jumps,thus playing an important role in solute diffusion.At the end of the Cu cluster evolution,the simulations of the average radius and number density of the clusters are consistent with the experimental data,which indicates that the proposed simulation model is applicable and effective.For the simulation of the annealing process,it is found that the evolution of the cluster size roughly follows the 1/2 time power law with the increase in radius during the growth phase and the 1/3 time power law during the coarsening phase.In addition,the main difference between neutron and ion irradiation is the growth and evolution process of the copper-vacancy clusters.The aggregation of vacancy clusters under ion irradiation suppresses the migration and coarsening of the clusters,which ultimately leads to a smaller average radius of the copper clusters.Our proposed simulation model can supplement experimental analyses and provide a detailed evolution mechanism of vacancy-enhanced precipitation,thereby providing a foundation for other elemental precipitation research.
基金the National Key Research and Development Program of China(Grant No.2017YFB0702401)the National Natural Science Foundation of China(Grant No.51631005).
文摘To shed a light on Xe bubble nucleation in U–Mo fuel from the view of primary irradiation damage,a reported U–Mo–Xe potential under the framework of embedded atom method has been modified within the range of short and intermediate atomic distance.The modified potential can better describe the interactions between energetic particles,and can accurately reproduce the threshold displacement energy surface calculated by the first-principles method.Then,molecular dynamics simulations of primary irradiation damage in U–Mo–Xe system have been conducted under different contents.The raise of Xe concentration brings about a remarkable promotion in residual defect quantity and generates bubbles in more overpressured state,which suggests an acceleration of irradiation damage under the accumulation of the fission gas.Meanwhile,the addition of Mo considerably reduces the residual defect count and hinders irradiation-induced Xe diffusion especially at high contents of Xe,corroborating the importance of high Mo content in mitigation of irradiation damage and swelling behavior in U–Mo fuel.In particular,the variation of irradiation damage with respect to contents suggests a necessity of taking into account the influence of local components on defect evolution in mesoscale simulations.
文摘AIM:To evaluate whether anterior cruciate ligament(ACL) allograft irradiation is effective for sterility without compromising graft integrity and increasing failure rate.METHODS:A literature search was conducted using Pub Med,Cochrane,and Google.The following search terms were used:"Gamma irradiation AND anterior cruciate ligament AND allograft" with a return of 30 items.Filters used included:English language,years 1990-2015.There were 6 hits that were not reviewed,as there were only abstracts available.Another 5 hits were discarded,as they did not pertain to the topic of interest.There were 9 more articles that were excluded:Three studies were performed on animals and 6 studies were meta-analyses.Therefore,a total of 10 articles were applicable to review.RESULTS:There is a delicate dosing crossover where gamma irradiation is both effective for sterility without catastrophically compromising the structural integrity of the graft.Of note,low dose irradiation is considered less than 2.0 Mrad,moderate dose is between 2.1-2.4 Mrad,and high dose is greater than or equal to 2.5 Mrad.Based upon the results of the literature search,the optimal threshold for sterilization was found to be sterilization at less than 2.2 Mrad of gamma irradiation with the important caveat of being performed at low temperatures.The graft selection process also must include thorough donor screening and testing as well as harvesting the tissue in a sterile fashion.Utilization of higher dose(≥ 2.5 Mrad) of irradiation causes greater allograft tissue laxity that results in greater graft failure rate clinically in patients after ACL reconstruction.CONCLUSION:Allograft ACL graft gamma irradiatedwith less than 2.2 Mrad appears to be a reasonable alternative to autograft for patients above 25 years of age.
文摘A green and convenient approach for the synthesis of a series of 5,5'-(arylmethylene)bis(4-hydroxythiazole-2(3H)-one)by the reaction of aryl aldehydes,monochloroacetic acid and ammonium thiocyanate in water/trifluoroethanol(TFE)(1:1)under ultrasound irradiation at room temperature is described.This method provides several advantages such as environmental friendliness,shorter time,excellent yields,and simple work-up procedure.
文摘Objective： The aim of the research was to study the effects of low-dose splenic irradiation and radiotherapy on immune system of patients with locally advanced non-small cell lung cancer （NSCLC）. Methods： Twelve cases of stage III NSCLC in Tumor Radiotherapy Center of our hospital （the Affiliated Hospital of Medical College Qingdao University, China） were collected from July 2011 to July 2012; all patients were under 75 years old with clear pathology, measurable lesions and good personal statement. They were randomly divided into combined treatment group （D1 ＋ D2） and control group （D1）. The control group （D1） only received radiotherapy to the chest; combined treatment group （D1 ＋ D2） received low-dose splenic irradiation plus conventional dose irradiation. Flow cytometry was used to detect the peripheral blood T lymphocyte immune indexes of patients before, during and after the treatment, classification by five blood cell analyzer was used to determine white blood cells, neutrophils, hemoglobin and platelet count. The radiation induced toxicity including esophagitis, pneumonia and gastrointestinal reaction was observed, as well as the dose when it happened. Results： There was no significant difference in the ratio between two groups in cells CD4＋, CD8＋ and CD4＋/CD8＋ after radiotherapy （P 〉 0.05）. There was no change in these indicators in combined treatment group after treatment （P 〉 0.05）, but it decreased in control group （P 〈 0.05）. There was no significant difference in the incidences of radiation esophagitis, pneumonia, gastrointestinal reactions and bone marrow suppression between two groups （P 〉 0.05）, but the patients in combined treatment group seemed to tolerate high dose well （P 〈 0.05）. Conclusion： Low-dose splenic irradiation combined with radiotherapy to the chest can alleviate the injury degree of acute radiation induced the toxicity of locally advanced NSCLC patients, through affect the patient＇s immune function.
文摘Around the world, radioactive sources have been widely used for decades to benefit humankind; industry food; health, etc. However, the malicious use of radiological sources poses a significant threat globally. As Irradiation facility for research the goal of this paper is to show a case study of application of nuclear security and nuclear security culture code of contact in irradiation facility using cobalt 60. And it will show the necessary work done to achieve the goal of protection of radioactive material and continue working in safe conditions. This objective could not be achieved without the collaboration of all department involved in security and nuclear safety. In this work we applied the nuclear security and nuclear security culture procedures in order to define the type of system used to achieve the global objective in accordance with Global Threat Reduction Program to reduce the threat of a RDD （Radiological Dispersion Device） in collaboration with The United States Department of Energy＇s NNSA （National Nuclear Security Administration）. The objective of this paper is to share a local experience in upgrading security with return of experience in practice and very good collaboration with general direction of national security and all departments involved in security and nuclear safety.
文摘This paper is devoted to the study of the potentiality of the Fricke dosimeter for the characterization of the highly energetic (62.1 MeV) α particles beams generated by a new cyclotron facility, namely ARRONAX started in 2009. Such for this high energetic α beam, in situ dosimetry is performed in order to avoid radiation safety inconvenience and to earn run time of irradiation. Therefore, an in situ Fricke dosimetry protocol is developed and its reliability is checked by comparison with other experiments carried out by using the traditional method (ex situ Fricke dosimetry) within another cyclotron facility (CEMHTI) and by comparison with literature data. To author’s knowledge, it is the first time that Fricke dosimetry is performed during the α irradiation experiment. The results of these in situ dosimetry experiments show that the value of ferric ions radiolytic yield (G(Fe3+) = (11.7 ± 1.2) 10–7 mol?J–1) extrapolated from literature data can be used for this higher energy of α particles (Eα = 62.1 MeV).
文摘Solar energy is the raw material and main source for several applications of renewable energy systems;thus, knowledge about the intensity of solar irradiation is essential for efficiency of these systems. Electric energy sources capable of meeting the growing demands of society with minimal impacts to the environment and high efficiency have been object of research in the last decade. In this context, the conversion of sunlight into electricity through photovoltaic cells has become one of the most encouraged and used resources in the world. However, the most unpredictable factor, which hampers capturing solar irradiation, preventing a proper conversion of sunlight into electricity, is the presence of clouds in the sky. Many methods of tracking and prediction of irradiation were proposed to increase efficiency in the production of energy by photovoltaic cells. This article presents an updated review on the mechanisms used for tracking and irradiation prediction, and their respective methods. It begins with a brief review on photovoltaic systems and classification of its mechanisms. Then, it presents a detailed overview on the evolution of mechanisms and their corresponding methods for tracking and irradiation prediction. Finally, the authors conclude with an analysis of performance efficiency of the mechanisms and their corresponding methods presented, describing the pros and cons of the most significant proposals for tracking and irradiation prediction.
文摘Arabidopsis thaliana is one of the most commonly used model plants due to its short life cycle and concise genome.As a novel physical mutagen, heavy ion beams have been widely used in plant breeding. The most significant advantages of heavy ion beams are the higher linear energy transfer (LET) and relative biological effectiveness (RBE), inducing a broad spectrum of mutation phenotypes even at low irradiation[1]. In order to investigate the effects on DNA behavior of Arabidopsis thaliana mutants induced by carbon ion irradiations, inter-simple sequence repeat (ISSR), a DNA-based molecular marker technique, was performed to assess the genetic polymorphism.
基金supported by the Science and Technology Planning Project of Fujian Province(No.2023Y4015)the Marine and Fishery Development Special Fund of Xiamen(No.23YYST064QCB36)the Natural Science Foundation of Fujian Province(No.2021J011210).
文摘The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by depositing Pt and RuO_(2)particles onto g-C_(3)N_(4).The physicochemical properties of photocatalysts were explored by X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),X-ray diffraction(XRD),and UV–vis diffuse reflectance spectrometer(UV–vis DRS).The photocatalysts were then applied to the removal of both NH_(4)^(+)-N and bacteria from simulated mariculture wastewater.The results clarified that the removals of both NH_(4)^(+)-N and bacteria were in the sequence of g-C_(3)N_(4)<RuO_(2)/g-C_(3)N_(4)<Pt/g-C_(3)N_(4)<Pt/RuO_(2)/g-C_(3)N_(4).This magnificent photocatalytic ability of Pt/RuO_(2)/g-C_(3)N_(4)can be interpreted by the transfer of holes from g-C_(3)N_(4)to RuO_(2)to facilitate the in situ generation of HClO from Cl^(−)in wastewater,while Pt extracts photogenerated electrons for H_(2)formation to enhance the reaction.The removal of NH_(4)^(+)-N and disinfection effect were more pronounced in simulated seawater than in purewater.The removal efficiency ofNH_(4)^(+)-N increases with an increase in pH of wastewater,while the bactericidal effect was more significant under a lower pH in a pH range of 6–9.In actual seawater aquaculture wastewater,Pt/RuO_(2)/g-C_(3)N_(4)still exhibits effective removal efficiency of NH_(4)^(+)-N and bactericidal performance under sunlight.This study provides an alternative avenue for removement of NH_(4)^(+)-N and bacteria from saline waters under sunlight.
基金the National Natural Science Foun-dation of China(Nos.U2241235,U2167213 and U2067218)the Project funded by the Science&Technology Department of Sichuan Province(No.21MZGC0400,No.2022JDJQ0021)+3 种基金the China National Nuclear Corporation(CNNC)Science Fund for Talented Young Scholars(No.CNNC-2021-31)the Funds of Science and Technol-ogy on Reactor Fuel and Materials Laboratory(No.6142A06190510)the fund from the Fundamental Research Funds for the Cen-tral Universities(No.N2202020)XingLiao Talent Plan(No.XLYC2203202).
文摘The Mg alloys with combination of high strength and excellent irradiation resistance are currently re-quired for research reactors.In this work,the novel Mg-3Mn-0.5Ca alloy with a high strength of over 300 MPa has been fabricated via co-addition of Mn and Ca elements.Moreover,the Xe ion implantation(300℃/4.5×10^(15)ions/cm^(2))is conducted for pure Mg,Mg-3Mn and Mg-3Mn-0.5Ca alloys.Microstruc-ture characterization shows that the number density of dislocation loops is comparable between Mg-3Mn and pure Mg,while the phase boundary of nano-Mn particles could act as the sink to absorb more Xe atoms,resulting in the abundant formation of Xe bubbles in the matrix of irradiated Mg-3Mn alloy.With further minor addition of Ca element,the formation of Xe bubbles and dislocation loops in Mg-3Mn-0.5Ca alloy has been obviously suppressed,and the abundant grain boundaries(GBs)due to grain refinement then act as the sink region for Xe precipitation.The limited number density of Xe bubbles leads to the extremely low swelling ratio in Mg-3Mn-0.5Ca alloy,∼0.08%.The result above suggests that the Mn and Ca co-addition could enhance the mechanical properties and irradiation tolerance of Mg alloys,si-multaneously.The present low-alloying strategy would provide a new design reference for novel nuclear materials.
文摘UV irradiation hydrogen peroxide （H202） system is used as an effective, easy and low-cost combined depolymerization technique to produce oligosaccharides from chitosan. UV-Vis spectroscopic studies explained that with increasing treatment time, the absorption of the depolymerized chitosan solution has increased, indicating the increase in the carbonyl and amino groups in their structure. Fourier transform infrared spectroscopy and nuclear magnetic resonance （1H NMR） analysis showed that the 1,4-β-D-glucoside linkages of chitosan are degraded without important changes in chemical structure of decomposed samples. X-ray diffraction patterns verified the polymerization of chitosan to produce oligomers, changing in structure from crystalline to amorphous. Viscosity-average molecular weight measurements of fragmented chitosan samples and MarkHouwink equation are used to demonstrate the efficiency of this depolymerization method. Finally, the obtained results ascertained that this combined method could produce water soluble chitosan with significant efficiency and no essential change in its chemical structure.UV irradiation hydrogen peroxide （H202） system is used as an effective, easy and low-cost combined depolymerization technique to produce oligosaccharides from chitosan. UV-Vis spectroscopic studies explained that with increasing treatment time, the absorption of the depolymerized chitosan solution has increased, indicating the increase in the carbonyl and amino groups in their structure. Fourier transform infrared spectroscopy and nuclear magnetic resonance （1H NMR） analysis showed that the 1,4-β-D-glucoside linkages of chitosan are degraded without important changes in chemical structure of decomposed samples. X-ray diffraction patterns verified the polymerization of chitosan to produce oligomers, changing in structure from crystalline to amorphous. Viscosity-average molecular weight measurements of fragmented chitosan samples and MarkHouwink equation are used to demonstrate the efficiency of this depolymerization method. Finally, the obtained results ascertained that this combined method could produce water soluble chitosan with significant efficiency and no essential change in its chemical structure.
基金National Key Research and Development Program of China(2020YFA0710302)The Major Research Plan of the National Natural Science Foundation of China(91963206)+2 种基金The National Natural Science Foundation of China(52072169,51972164,51972167,22279053)The Fundamental Research Funds for the Central Universities(14380193)The Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2019ZT08L101).
文摘On the surfaces of celestial bodies with no or thin atmospheres,such as the Moon and Mars,the solar wind irradiation process leads to the formation of hydrogen and helium enriched regions in the extraterrestrial soil particles.However,soil particles on the Earth with the similar composition lack such structures and properties.This discrepancy raises a key question whether there is a direct relationship between solar wind irradiation and the alterations in the structure and chemical performance of extraterrestrial materials.To address this question,this work investigates the effects of proton irradiation,simulating solar wind radiation,on the structure and photothermal catalytic properties of the classic catalyst In_(2)O_(3).It reveals that proton irradiation induces structural features in In_(2)O_(3) analogous to those characteristics of solar wind weathering observed in extraterrestrial materials.Furthermore,after proton beam irradiation with an energy of 30 keV and a dose of 3×10^(17) protons·cm^(-2),the methanol production yield of the In_(2)O_(3) catalyst increased to 2.6 times of its preirradiation level,and the methanol selectivity improved to 2.1 times of the original value.This work provides both theoretical and experimental support for the development of high-efficiency,radiation-resistant photothermal catalysts.
基金support from the National Natural Science Foundation of China(Nos.12302083,U2267252,12372069,and 12172123)the China Postdoctoral Science Foundation(Nos.2023M731061 and BX20230109)+1 种基金the Natural Science Foundation of Hunan Province(No.2022JJ20001)the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20230420).
文摘High-entropy alloys(HEAs)exhibit the excellent elevated-temperature performance and irradiation resistance due to the important core effect of serious lattice distortion for impeding dislocation motion,as candidate materials for nuclear applications.Despite the growth of the nuclear power sector,the effects of high-temperature and high-dose irradiation-induced voids on the mechanical properties of HEA in higher power nuclear reactors remain insufficiently researched,hindering its industrial application.In this study,we establish a consistent parameterization crystal plastic constitutive model for the hardening and creep behaviors of HEA,incorporating the spatial distribution of void size and shape effects,in contrast to traditional creep models that rely on temperature-related fitting parameters of the phenomenological power law equation.The model matches well with experimental data at different temperatures and irradiation doses,demonstrating its robustness.The effects of irradiation dose,temperature,and degree of lattice distortion on irradiation hardening and creep behavior of void-containing HEA are investigated.The results indicate that HEA with high lattice distortion exhibits better creep resistance under higher stress loads.The yield stress of irradiated HEA increases with increasing irradiation dose and temperature.The creep resistance increases with increasing irradiation dose and decreases with increasing irradiation temperature.The increase in irradiation dose causes a specific morphological transformation from spherical to cubic voids.The modeling and results could provide an effective theoretical way for tuning the yield strength and alloy design in advanced HEAs to meet irradiation properties.
