The ^(232)Th(n,f)cross section is very important in basic nuclear physics and applications based on the Th/U fuel cycle.Using the time-of-flight method and a multi-cell fast-fission ionization chamber,a novel measurem...The ^(232)Th(n,f)cross section is very important in basic nuclear physics and applications based on the Th/U fuel cycle.Using the time-of-flight method and a multi-cell fast-fission ionization chamber,a novel measurement of the^(232)Th(n,f)cross sec-tion relative to^(235)U in the 1–200 MeV range was performed at the China Spallation Neutron Source Back-n white neutron source(Back-n).The fission event-neutron energy spectra of^(232)Th and^(235)U fission cells were measured in the single-bunch mode.Corrected 232Th/235U fission cross-sectional ratios were obtained,and the measurement uncertainties were 2.5–3.7%for energies in the 2–20 MeV range and 3.6–6.2%for energies in the 20–200 MeV range.The^(232)Th(n,f)cross section was obtained by introducing the standard cross section of^(235)U(n,f).The results were compared with those of previous theoreti-cal calculations,measurements,and evaluations.The measured 232Th fission cross section agreed with the main evaluation results in terms of the experimental uncertainty,and 232Th fission resonances were observed in the 1–3 MeV range.The present results provide^(232)Th(n,f)cross-sectional data for the evaluation and design of Th/U cycle nuclear systems.展开更多
Stroke is one of the leading causes of disability and death globally.It occurs when a major artery is occluded in the brain and leads to death of cells within the injured tissue.(+)-Borneol,a simple bicyclic monoterpe...Stroke is one of the leading causes of disability and death globally.It occurs when a major artery is occluded in the brain and leads to death of cells within the injured tissue.(+)-Borneol,a simple bicyclic monoterpene extracted from traditional Chinese medicine,is widely used in various types of diseases.However,no study has proved the effects of(+)-borneol on functional recovery from permanent ischemic stroke and the mechanism is still unknown.Here,we report that in the rat model of permanent cerebral ischemia,we found that(+)-borneol(1.0 mg/kg) significantly ameliorated infarct size and neurological scores via reducing the expression of inducible nitric oxide synthase(iNOS)and tumor necrosis factor-alpha(TNF-α) in a dose dependent manner.Notably,(+)-borneol showed long-term effects on the improvement of sensorimotor functions in the photothrombotic model of stroke,which decreased the number of foot faults in the grid-walking task and forelimb asymmetry scores in the cylinder task,at least in part through reducing loss of dendritic spines in the length,brunch number and density.These findings suggest that(+)-borneol could serve as a therapeutic target for ischemic stroke.展开更多
Back-streaming neutrons from the spallation target of the China Spallation Neutron Source(CSNS)that emit through the incoming proton channel were exploited to build a white neutron beam facility(the so-called Back-n w...Back-streaming neutrons from the spallation target of the China Spallation Neutron Source(CSNS)that emit through the incoming proton channel were exploited to build a white neutron beam facility(the so-called Back-n white neutron source),which was completed in March 2018.The Back-n neutron beam is very intense,at approximately 29107 n/cm2/s at 55 m from the target,and has a nominal proton beam with a power of 100 kW in the CSNS-I phase and a kinetic energy of 1.6 GeV and a thick tungsten target in multiple slices with modest moderation from the cooling water through the slices.In addition,the excellent energy spectrum spanning from 0.5 eV to 200 MeV,and a good time resolution related tothe time-of-flight measurements make it a typical white neutron source for nuclear data measurements;its overall performance is among that of the best white neutron sources in the world.Equipped with advanced spectrometers,detectors,and application utilities,the Back-n facility can serve wide applications,with a focus on neutron-induced cross-sectional measurements.This article presents an overview of the neutron beam characteristics,the experimental setups,and the ongoing applications at Backn.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11675155,11790321,and 12075216)the National Key Research and Development Plan(No.2016YFA0401603).
文摘The ^(232)Th(n,f)cross section is very important in basic nuclear physics and applications based on the Th/U fuel cycle.Using the time-of-flight method and a multi-cell fast-fission ionization chamber,a novel measurement of the^(232)Th(n,f)cross sec-tion relative to^(235)U in the 1–200 MeV range was performed at the China Spallation Neutron Source Back-n white neutron source(Back-n).The fission event-neutron energy spectra of^(232)Th and^(235)U fission cells were measured in the single-bunch mode.Corrected 232Th/235U fission cross-sectional ratios were obtained,and the measurement uncertainties were 2.5–3.7%for energies in the 2–20 MeV range and 3.6–6.2%for energies in the 20–200 MeV range.The^(232)Th(n,f)cross section was obtained by introducing the standard cross section of^(235)U(n,f).The results were compared with those of previous theoreti-cal calculations,measurements,and evaluations.The measured 232Th fission cross section agreed with the main evaluation results in terms of the experimental uncertainty,and 232Th fission resonances were observed in the 1–3 MeV range.The present results provide^(232)Th(n,f)cross-sectional data for the evaluation and design of Th/U cycle nuclear systems.
基金supported by grants from National Natural Science Foundation of China(91232304, 31530091,81571188 and 81222016)the Natural Science Foundation of Jiangsu Province(BK2011029)Distinguished Young Scientists Fund(BK20130040)
文摘Stroke is one of the leading causes of disability and death globally.It occurs when a major artery is occluded in the brain and leads to death of cells within the injured tissue.(+)-Borneol,a simple bicyclic monoterpene extracted from traditional Chinese medicine,is widely used in various types of diseases.However,no study has proved the effects of(+)-borneol on functional recovery from permanent ischemic stroke and the mechanism is still unknown.Here,we report that in the rat model of permanent cerebral ischemia,we found that(+)-borneol(1.0 mg/kg) significantly ameliorated infarct size and neurological scores via reducing the expression of inducible nitric oxide synthase(iNOS)and tumor necrosis factor-alpha(TNF-α) in a dose dependent manner.Notably,(+)-borneol showed long-term effects on the improvement of sensorimotor functions in the photothrombotic model of stroke,which decreased the number of foot faults in the grid-walking task and forelimb asymmetry scores in the cylinder task,at least in part through reducing loss of dendritic spines in the length,brunch number and density.These findings suggest that(+)-borneol could serve as a therapeutic target for ischemic stroke.
基金This work was jointly supported by the National Key Research and Development Program of China(No.2016YFA0401600)National Natural Science Foundation of China(Nos.11235012 and 12035017)+1 种基金the CSNS Engineering Projectthe Back-n Collaboration Consortium fund。
文摘Back-streaming neutrons from the spallation target of the China Spallation Neutron Source(CSNS)that emit through the incoming proton channel were exploited to build a white neutron beam facility(the so-called Back-n white neutron source),which was completed in March 2018.The Back-n neutron beam is very intense,at approximately 29107 n/cm2/s at 55 m from the target,and has a nominal proton beam with a power of 100 kW in the CSNS-I phase and a kinetic energy of 1.6 GeV and a thick tungsten target in multiple slices with modest moderation from the cooling water through the slices.In addition,the excellent energy spectrum spanning from 0.5 eV to 200 MeV,and a good time resolution related tothe time-of-flight measurements make it a typical white neutron source for nuclear data measurements;its overall performance is among that of the best white neutron sources in the world.Equipped with advanced spectrometers,detectors,and application utilities,the Back-n facility can serve wide applications,with a focus on neutron-induced cross-sectional measurements.This article presents an overview of the neutron beam characteristics,the experimental setups,and the ongoing applications at Backn.
