Brain plasticity is heterogeneous in mammals:Brain regeneration and repair are the dream of every neurobiologist as well as every common citizen in the world who knows that most neurological diseases,dementia and oth...Brain plasticity is heterogeneous in mammals:Brain regeneration and repair are the dream of every neurobiologist as well as every common citizen in the world who knows that most neurological diseases,dementia and other age-related problems affecting the central nervous system(CNS)do represent a heavy health and social burden.Efficacious re-generative processes are not" a natural property of the mammalian CNS, rather, due to evolutionary constraints they seem substantially reduced (if compared to those occurring in non-mammalian vertebrates) and hardly inducible by therapeutic approaches (reviewed in Martino et al., 2011).展开更多
The transmutation of long-lived fission products through spallation induced by light nuclides was investi-gated for the purpose of determining the feasibility of this approach for long-lived fission products,in both e...The transmutation of long-lived fission products through spallation induced by light nuclides was investi-gated for the purpose of determining the feasibility of this approach for long-lived fission products,in both economic and environmental terms.The cross-section data were obtained from the TALYS Evaluated Nuclear Data Library(TENDL).A thick target model was used to study the consumption of the target isotopes in the transmutation process.The transmutation yield was calculated using the highest beam intensity available with the China initiative accelerator-driven system.It was found that the light nuclide-induced spallation reaction can significantly reduce the radio toxicity of the investigated long-lived fission products.Using the transmutation target made of elemental LLFP and the proton beam with an intensity of 5 mA,the consumption of 90 Sr,93 Zr,107 Pd,or 137 Cs can reach approximately 500 g per year.展开更多
We observe the spectra of molybdenum for the first time since the first wall of our experimental advanced superconducting tokamak (EAST) was changed mainly to molybdenum tiles. A large amount of molybdenum accumulat...We observe the spectra of molybdenum for the first time since the first wall of our experimental advanced superconducting tokamak (EAST) was changed mainly to molybdenum tiles. A large amount of molybdenum accumulated in the central plasma where the long-lived m = 1 mode instability bursts is shown. Molybdenum is proved to be the main impurity species observed during the formation and lifetime of impurity-induced long-lived m= 1 mode. This may indicate that a close relationship exists between the high-Z impurity accumulation and the occurrence of long-lived m = 1 mode in EAST plasmas.展开更多
Background The accelerator-driven subcritical transmutation system(ADS)is an advanced technology for the harmless disposal of nuclear waste.A theoretical analysis of the ingredients and content of nuclear waste,partic...Background The accelerator-driven subcritical transmutation system(ADS)is an advanced technology for the harmless disposal of nuclear waste.A theoretical analysis of the ingredients and content of nuclear waste,particularly long-lived waste in a pressurized water reactor(PWR),will provide important information for future spent fuel disposal.Purpose The present study is an attempt to investigate the yields of isotopes in the neutron-induced fission process and estimate the content of long-lived ingredients of nuclear waste in a PWR.Method We combined an approximation of the mass distribution of five Gaussians with the most probable charge model(Zp model)to obtain the isotope yields in the^(235)U(n,f)and^(239)Pu(n,f)processes.The potential energy surface based on the concept of a di-nuclear system model was applied to an approximation using five Gaussian functions.A mathematical formula for the neutron spectrum in a PWR was established,and sets of differential equations were solved to calculate the content of long-lived nuclides in a PWR.Results The calculated isotopic fission yields were in good agreement with the experimental data.Except for 238U,the contents of^(239)Pu,^(240)Pu,^(241)Pu,^(242)Pu,^(237)Np,^(235)U,and^(236)U are predominant in the PWR after reaching a discharge burnup.In addition,some isotope pairs of heavy nuclei reach a similar value after stabilization,which can be explained by the decay chain and effective fission crosssections.For fission fragments,we simulated the content evolution of some long-lived nuclides^(90)Sr,^(107)Pd,^(135)Cs,and their isobars^(90)Rb,^(107)Rh,and^(135)Xe during a fuel cycle in a PWR.The variations in the inventories of uranium and plutonium were in good agreement with the data in Daya Bay.Conclusion A new method is proposed for the prediction of the isotopic fission yield.The inventory of long-lived nuclides was analyzed and predicted after reaching a discharge burnup.展开更多
The B3LYP/6-31G^* level of theory was used for the optimization of nonclassical platinum drugs with planar aromatic heterocycle ligands in addition to their monoaqua species, diaqua species and monofunctional adducts...The B3LYP/6-31G^* level of theory was used for the optimization of nonclassical platinum drugs with planar aromatic heterocycle ligands in addition to their monoaqua species, diaqua species and monofunctional adducts. Single point calculations were performed on optimized geometries using the MP2/6-31G^** method, and the Lanl2dz pseudo potential for the Pt atom remained constant in all calculations. It can be easily seen that the trans effect can influence both geometrical structures and bond dissociating energies (BDEs). On the basis of our calculation, we get that the long-lived monofunctional adducts with chloride ligand may be in existence, because they possessed higher stability energies, easily dissociated chloride compared with the monoaqua species dissociating chloride and that replacement of the first chloride by bases became exothermic in solution. Our calculated results also demonstrate that the strongest H-bonds appear in the complexes of q-wG and t-wG using different methods. In comparison with adenine complexes, the corresponding guanine complexes possess larger interaction energies as well as higher stability energies either corrected by basis set superposition error (bsse) of Boys-Bernardi counterpoise method or uncorrected both in gas phase and in solution with one exception that the stability energy of q-CIA complex in solution is larger than that of q,CIG complex. Finally, the nature of bond was analyzed in terms of partial charges distribution based on NBO population.展开更多
For the Na + I2 collision system, theoretical study is performed on the QCISD(T) level by using ab initio method. The ab initio potential energy surfaces are got and on them the long-lived complexes are found and opti...For the Na + I2 collision system, theoretical study is performed on the QCISD(T) level by using ab initio method. The ab initio potential energy surfaces are got and on them the long-lived complexes are found and optimized. These results verify the crossed molecule beam experimental phenomenon and the detailed geometry structures are given for the first time. The role of the complexes in the reaction path is also described in detail.展开更多
An intense 14 MeV neutron source facility named OKTAVIAN was installed in the A15 building,Osaka University in 1981.Along the operation period,new radioisotopes with various half-life have been produced as neutron act...An intense 14 MeV neutron source facility named OKTAVIAN was installed in the A15 building,Osaka University in 1981.Along the operation period,new radioisotopes with various half-life have been produced as neutron activation products in its concrete wall shield.In this work,we investigated the concrete wall in the heavy irradiation room of OKTAVIAN using gamma spectrometry method to discover the presence of radioisotope having large half-life value(long-lived radioisotope)as neutron activation products.Computational simulations were performed prior to measurement to predict the presence of long-lived radioisotopes by employing MCNP5 and FISPACT codes.A pre-calibrated Germanium detector with high energy resolution was employed to measure the concrete.Several long-lived activation products have been observed such as 152 Eu,54 Mn,65 Zn,22 Na and 60 Co.The activity of each radioisotope was derived after estimating the detector efficiency using MCNP5.As a result of the measurement and analysis,the followings are concluded:(1)Though presence of activation products represents radiological risk to everyone who performs an experimental activity in the irradiation room of the OKTAVIAN facility,the present result shows that past experiments were carried out safely without any significant additional exposure dose coming from the wall for the last 38 years.(2)The approximated total fluence of D-T neutrons to the wall was successfully estimated from the produced radioisotope,152 Eu,because it has the longest half-life of 13.5 years among the observed radioisotopes.(3)From the results of(1)and(2),it could be possible to estimate the total activity of the concrete wall in the OKTAVIAN facility,which is very essential and important information,because this would be very valuable for decommissioning or disposal of the facility in the future.展开更多
The iconic image of a giant radiating dyke swarm subsequently fragmented into three pieces via supercontinental breakup was produced by Paul May in1971(see next page).That figure presented a large part of
Bulk thanks to their characteristics of being environmentally benign,easily fabricated and relatively stable,dyesensitized solar cells(DSSCs)have attracted attention over decades as a potential alternative to solar en...Bulk thanks to their characteristics of being environmentally benign,easily fabricated and relatively stable,dyesensitized solar cells(DSSCs)have attracted attention over decades as a potential alternative to solar energy conversion[1].However,as L.M.Peter pointed out in 2011,'although much more is now known about the physical and chemical processes taking place during operation of the DSSCs,the exponential increase in research effort during this period has not been matched by large increases in efficiency'[2].To date,展开更多
Systematization for the maintenance of buildings enables their supporting system to be more practical than before. This study aims to make the maintenance and the long-term repairs for the buildings to be easier. In J...Systematization for the maintenance of buildings enables their supporting system to be more practical than before. This study aims to make the maintenance and the long-term repairs for the buildings to be easier. In Japan, 30-40-year-old buildings seem to have been planned and built with little thought about their future maintenances, which have made them very difficult to be repaired on a large scale. This is why effective management systems about dealing with the data should be strongly suggested. Since the Building Standard Law was amended on April 1, 2008, in Japan, the regular investigation and report for particular buildings are legally obligated every three years, thus a variety of useful data can be obtained through Kitakyushu City cases as well as former data personally obtained. With those data used usefully, systematization for the maintenance of the buildings will produce satisfactory results by building up a connection between those data and the long-term repair planning.展开更多
<strong>Introduction</strong>.<span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> The molecular biological mechanism ...<strong>Introduction</strong>.<span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> The molecular biological mechanism of the increased incidence of the various types of cancer in obesity or type 2 diabetes in rodents or humans has largely been resolved in recent years. By contrast, the molecular biological mechanism of the decreased, not increased, incidence of the various types of cancer in the homozygous long-lived Ames dwarf mice still remains unresolved. </span><b><span style="font-family:Verdana;">Objective.</span></b><span style="font-family:Verdana;"> The first objective of the present study was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the increase, not decrease, in the expression of p27Kip1, a cell cycle repressor protein. The second objective was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the decrease, not increase, in the levels of glucose or insulin. </span><b><span style="font-family:Verdana;">Methods.</span></b><span style="font-family:Verdana;"> To achieve these objectives, we first performed western immunoblot analysis of the hepatic expression of p27Kip1 protein. We then performed, using a human breast cancer cell line </span><i><span style="font-family:Verdana;">in</span></i> <i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;">, the luciferase reporter plasmid assay to determine whether the translation initiation activity of the p27Kip1 mRNA is increased when the concentrations of either glucose or insulin are decreased. </span><b><span style="font-family:Verdana;">Results and Conclusion. </span></b><span style="font-family:Verdana;">The results of the first objective indicated that the hepatic expression of p27Kip1 protein was up-regulated in the homozygous long-lived Ames dwarf mice as expected. We also found that the lower concentrations of glucose or insulin increased the translation initiation activity of the p27Kip1 mRNA.</span></span></span></span>展开更多
A summary is given on the activation cross section measurements performed byChina Institute of Atomic Energy(CIAE),Lanzhou University(LU),Peking University(PU)and Sichuan University(SU)from 1989 to 1994 for ge...A summary is given on the activation cross section measurements performed byChina Institute of Atomic Energy(CIAE),Lanzhou University(LU),Peking University(PU)and Sichuan University(SU)from 1989 to 1994 for generation of long-lived radionuclides of im-portance in fusion reactor technology.The cross sections are measured for the reactions <sup>109</sup>Ag(n,2n)<sup>108</sup>Ag<sup>m</sup>,<sup>151</sup>Eu(n,2n)<sup>150</sup>Eu<sup>m</sup>,<sup>153</sup>Eu(n,2n)<sup>152</sup>Eu<sup>8</sup>,<sup>159</sup>Tb(n,2n)<sup>158</sup>Tb,<sup>179</sup>Hf(n,2n )<sup>178</sup>Hf<sup>m2</sup>,<sup>182</sup>W(n,n′α)<sup>178</sup>Hf<sup>m2</sup>,<sup>187</sup>Re(n,2n)<sup>186</sup>Re<sup>m</sup> and <sup>193</sup>Ir(n,2n)<sup>192</sup>Ir<sup>m2</sup>at 14 MeV,<sup>109</sup>Ag(n,2n)<sup>108</sup>Ag<sup>m</sup>,<sup>151</sup>Eu(n,2n)<sup>150</sup>Eu<sup>m</sup>,<sup>159</sup>Tb(n,2n)<sup>158</sup>Tb and <sup>179</sup>Hf(n,2n)<sup>178</sup>Hf<sup>m2</sup>at 9.5 and 9.9 MeV,and<sup>98</sup>Mo(n,γ)<sup>199</sup>Mo(β<sup>-</sup>)→<sup>99</sup>Tc,<sup>165</sup>Ho(n.γ)<sup>166</sup>Ho<sup>m</sup> and <sup>151</sup>Eu(n,γ)<sup>152</sup>Eu<sup>8</sup> in the energy range of20~1100 keV.Some of them were calculated by systematic and HFTT code,which was basedon the compound nucleus evaporation and the preequilibrium exciton model.展开更多
Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission products.In this study,the Geant4 toolkit was used to simulate the i...Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission products.In this study,the Geant4 toolkit was used to simulate the inter-action between a deuteron beam at 500 MeV and a com-posite target composed of alternating lead-bismuth eutectic(LBE)and water.The water was used because it may be employed as a target coolant.The energy spectrum,neu-tron yield,average energy,and total energy of the emitted neutrons were calculated for different thicknesses and thickness ratios between the LBE and water.For a constant target thickness,the neutron yield increases with an increasing thickness ratio of LBE to H 2 O,while the aver-age energy of the emitted neutrons decreases with an increasing in the aforementioned thickness ratio.These two aspects support the use of a pure target,either LBE or water.However,with an increasing LBE-to-H 2 O thickness ratio,the total energy of the emitted neutrons increases and then decreases.This result supports the addition of water into the LBE target.The angular distributions of the emitted neutrons show that the rear of the target is suit-able for loading nuclear waste containing minor actinides and long-lifetime fission products.展开更多
Understanding the effects of disturbance on seed rain is critical to predict changes in forest species composition and diversity.Logging effects on seed rain in a mixed conifer-hardwood forest complex in southern Braz...Understanding the effects of disturbance on seed rain is critical to predict changes in forest species composition and diversity.Logging effects on seed rain in a mixed conifer-hardwood forest complex in southern Brazil were evaluated.One year of seed rain data were collected from a large-scale observational experiment in logged and protected forests and quantity and average seed size weighted by species abundance(CWM)were compared between old-growth and logged stands 55 years after logging activities.Using these data,variations in frequency of functional groups of species in the seed rain were examined to see if they could be attributed to logging.Results show that the number of seeds per trap was highly right-skewed,ranging from 13 to 12,788 seeds per trap in one year.Seed rain was affected by logging history,with seed traps in old-growth plots receiving significantly less seeds than traps in logged plots.All species included mean seed size weighted by species abundance were significantly smaller in logged than in old-growth forests.This difference persisted after the exclusion of Arawcaria a large-seeded pioneer which was intensively logged,although the difference of seed size between the two forest classes was greatly reduced.Species abundance in the seed rain differed significantly from the established tree community,between logged and oldgrowth stands.The composition of the seed rain was much more variable than the composition of the established tree community and its points more scattered over the ordination space than the points corresponding to the protected forests.The number of collected seeds across different functional groups of species significantly differed between logged and old-growth plots.The seed rain of logged forests reflects their arrested succes sion as indicated by reduced abundance of functional groups such as pioneers,large seeded pioneers and A raucaria,as well as reduced functional diversity.S eed rain differences between logged and old-growth stands reflect the intensive logging of A.angustifolia.展开更多
In the presence of energetic particles(EPs),the long-lived mode(LLM) frequency multiplication with n=1,2,3,or higher is often observed on HL-2A,where n is the toroidal mode number.Hybrid kinetic-MHD model simulations ...In the presence of energetic particles(EPs),the long-lived mode(LLM) frequency multiplication with n=1,2,3,or higher is often observed on HL-2A,where n is the toroidal mode number.Hybrid kinetic-MHD model simulations of the energetic particle(EP) driven kink/fishbone modes on a static HL-2A-like tokamak using NIMROD code find that when the background plasma pressure is relatively high,and the EP pressure and the beam energy are relatively low,the mode frequency increases almost linearly with EP pressure,and the frequency is proportional to n(’frequency multiplication’),even in the absence of any equilibrium plasma rotation.In addition,the frequency multiplication persists as the safety factor at the magnetic axis q_(0)varies.In the absence of EPs,the growth rate of the 1/1 mode is the largest;however,as the EP pressure increases,the growth rate of 2/2 modes or 3/3 modes becomes dominant,suggesting that higher-n modes are more vulnerable to EPs.These results may shed light on the understanding of the toroidal mode number dependence of kink/fishbone modes in the advanced scenarios of tokamaks with weak or reversed central magnetic shear.展开更多
Carbon dots(CDs)with room-temperature phosphorescence(RTP)have attracted dramatically growing interest in optical functional materials.However,the photoluminescence mechanism of CDs is still a vital and challenging to...Carbon dots(CDs)with room-temperature phosphorescence(RTP)have attracted dramatically growing interest in optical functional materials.However,the photoluminescence mechanism of CDs is still a vital and challenging topic.In this work,we prepared CD-based RTP materials via melting boric acid with various lengths of alkyl amine compounds as precursors.The spatial effect on the structure and the RTP properties of CDs were systematically investigated.With the increase in carbon chain length,the interplanar spacing of the carbon core expands and crosslink-enhanced emission weakens,resulting in a decrease in the phosphorescence intensity and lifetimes.Meanwhile,based on triplet-to-singlet resonance energy transfer,we employed intense and long-lived phosphorescence CDs as the donor and short-lived fluorescent dyes as the acceptor to achieve long-lived multicolor afterglow.By the triplet-to-singlet resonance energy transfer,the afterglow color can change from green to orange.The afterglow lifetimes are more than 0.9 s.Thanks to the outstanding afterglow properties,the composites were used for timeresolved and multiple-color advanced anticounterfeiting.This work will promote the design of multicolor and long-lived afterglow materials and expand their applications.展开更多
The cross section for <sup>108</sup>Cd(n,p)<sup>108</sup>Ag<sup>m</sup> reaction is measured by the activationmethod at an incident neutron energy of 14.6±0.2MeV.The result i...The cross section for <sup>108</sup>Cd(n,p)<sup>108</sup>Ag<sup>m</sup> reaction is measured by the activationmethod at an incident neutron energy of 14.6±0.2MeV.The result is 18.1±3.3mb.展开更多
The cross sections of long-lived radionuclides of importance in fusionreactor technology are measured by activation method for <sup>137</sup>Ba(n,p)<sup>137</sup>Cs,<sup>182</sup>...The cross sections of long-lived radionuclides of importance in fusionreactor technology are measured by activation method for <sup>137</sup>Ba(n,p)<sup>137</sup>Cs,<sup>182</sup>W(n,n’x)<sup>178</sup>Hf<sup>m2</sup> and <sup>193</sup>Ir(n,2n)<sup>192</sup>Ir<sup>m2</sup> reactions at 14 MeV.The neutron fluencesare determined by the cross sections of <sup>93</sup>Nb(n,2n)<sup>92</sup>Nb<sup>m</sup>,<sup>54</sup>Fe(n,x)<sup>51</sup>Cr and<sup>54</sup>Fe(n,p)<sup>54</sup>Mn reactions.The induced gamma ray activities of the irradiated Ba<sub>2</sub>O<sub>3</sub>,Wand Ir samples and their monitor foils are measured by a calibrated Ge(Li)detector oran anti-Compton gamma ray spectrometer.展开更多
The cross sections for the formation of long-lived products <sup>108</sup>Ag<sup>m</sup>(6<sup>+</sup>,433a),<sup>150</sup>Eu<sup>m</sup>(5<sup>-<...The cross sections for the formation of long-lived products <sup>108</sup>Ag<sup>m</sup>(6<sup>+</sup>,433a),<sup>150</sup>Eu<sup>m</sup>(5<sup>-</sup>,36.9a),<sup>158</sup>Tb(3<sup>-</sup>,180a)and <sup>178</sup>Hf<sup>m2</sup>(16<sup>+</sup>,31a)are measured in the(n,2n)reaction on the elementsof <sup>109</sup>Ag,<sup>151</sup>Eu,<sup>159</sup>Tb and <sup>79</sup>Hf at neutron energies of 9.5 MeV and 0.9 MeV,respectively.The neu-tron fluence is obtained through the <sup>197</sup>Au(n,2n)<sup>196</sup>Au reaction.The D(d,n)<sup>3</sup>He reaction is used as neu-tron source at the tandem accelerator.The present results are compared with the averaged values of theo-retical cross sections and the experimental data.展开更多
基金supported by MIUR-PRIN2015(grant 2015Y5W9YP)University of Turin(Ricerca locale 2016)
文摘Brain plasticity is heterogeneous in mammals:Brain regeneration and repair are the dream of every neurobiologist as well as every common citizen in the world who knows that most neurological diseases,dementia and other age-related problems affecting the central nervous system(CNS)do represent a heavy health and social burden.Efficacious re-generative processes are not" a natural property of the mammalian CNS, rather, due to evolutionary constraints they seem substantially reduced (if compared to those occurring in non-mammalian vertebrates) and hardly inducible by therapeutic approaches (reviewed in Martino et al., 2011).
基金supported by the National Natural Science Foundation of China(No.11875328).
文摘The transmutation of long-lived fission products through spallation induced by light nuclides was investi-gated for the purpose of determining the feasibility of this approach for long-lived fission products,in both economic and environmental terms.The cross-section data were obtained from the TALYS Evaluated Nuclear Data Library(TENDL).A thick target model was used to study the consumption of the target isotopes in the transmutation process.The transmutation yield was calculated using the highest beam intensity available with the China initiative accelerator-driven system.It was found that the light nuclide-induced spallation reaction can significantly reduce the radio toxicity of the investigated long-lived fission products.Using the transmutation target made of elemental LLFP and the proton beam with an intensity of 5 mA,the consumption of 90 Sr,93 Zr,107 Pd,or 137 Cs can reach approximately 500 g per year.
基金Supported by the National Magnetic Confinement Fusion Science Program of China under Grant Nos 2013GB112004 and 2015GB103002the Natural Science Research Key Project of Education Department of Anhui Province under Grant No KJ2016A434+3 种基金the Doctoral Scientific Research Foundation of Anqing Normal University under Grant No 044-140001000024the National Natural Science Foundation of China under Grant Nos 11275231,11305212,11405212 and 11261140328the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology under Grant No 2014FXCX003the Hefei Science Center CAS Users with Potential Project under Grant No 2015HSC-UP007
文摘We observe the spectra of molybdenum for the first time since the first wall of our experimental advanced superconducting tokamak (EAST) was changed mainly to molybdenum tiles. A large amount of molybdenum accumulated in the central plasma where the long-lived m = 1 mode instability bursts is shown. Molybdenum is proved to be the main impurity species observed during the formation and lifetime of impurity-induced long-lived m= 1 mode. This may indicate that a close relationship exists between the high-Z impurity accumulation and the occurrence of long-lived m = 1 mode in EAST plasmas.
基金This work was supported by the National Natural Science Foundation of China(No.11605296)the Natural Science Foundation of Guangdong Province,China(No.2016A030310208)Fundamental Research Funds for Central Universities(No.18lgpy87).
文摘Background The accelerator-driven subcritical transmutation system(ADS)is an advanced technology for the harmless disposal of nuclear waste.A theoretical analysis of the ingredients and content of nuclear waste,particularly long-lived waste in a pressurized water reactor(PWR),will provide important information for future spent fuel disposal.Purpose The present study is an attempt to investigate the yields of isotopes in the neutron-induced fission process and estimate the content of long-lived ingredients of nuclear waste in a PWR.Method We combined an approximation of the mass distribution of five Gaussians with the most probable charge model(Zp model)to obtain the isotope yields in the^(235)U(n,f)and^(239)Pu(n,f)processes.The potential energy surface based on the concept of a di-nuclear system model was applied to an approximation using five Gaussian functions.A mathematical formula for the neutron spectrum in a PWR was established,and sets of differential equations were solved to calculate the content of long-lived nuclides in a PWR.Results The calculated isotopic fission yields were in good agreement with the experimental data.Except for 238U,the contents of^(239)Pu,^(240)Pu,^(241)Pu,^(242)Pu,^(237)Np,^(235)U,and^(236)U are predominant in the PWR after reaching a discharge burnup.In addition,some isotope pairs of heavy nuclei reach a similar value after stabilization,which can be explained by the decay chain and effective fission crosssections.For fission fragments,we simulated the content evolution of some long-lived nuclides^(90)Sr,^(107)Pd,^(135)Cs,and their isobars^(90)Rb,^(107)Rh,and^(135)Xe during a fuel cycle in a PWR.The variations in the inventories of uranium and plutonium were in good agreement with the data in Daya Bay.Conclusion A new method is proposed for the prediction of the isotopic fission yield.The inventory of long-lived nuclides was analyzed and predicted after reaching a discharge burnup.
基金This work was supported by the Science Foundation of Jinan University (639)
文摘The B3LYP/6-31G^* level of theory was used for the optimization of nonclassical platinum drugs with planar aromatic heterocycle ligands in addition to their monoaqua species, diaqua species and monofunctional adducts. Single point calculations were performed on optimized geometries using the MP2/6-31G^** method, and the Lanl2dz pseudo potential for the Pt atom remained constant in all calculations. It can be easily seen that the trans effect can influence both geometrical structures and bond dissociating energies (BDEs). On the basis of our calculation, we get that the long-lived monofunctional adducts with chloride ligand may be in existence, because they possessed higher stability energies, easily dissociated chloride compared with the monoaqua species dissociating chloride and that replacement of the first chloride by bases became exothermic in solution. Our calculated results also demonstrate that the strongest H-bonds appear in the complexes of q-wG and t-wG using different methods. In comparison with adenine complexes, the corresponding guanine complexes possess larger interaction energies as well as higher stability energies either corrected by basis set superposition error (bsse) of Boys-Bernardi counterpoise method or uncorrected both in gas phase and in solution with one exception that the stability energy of q-CIA complex in solution is larger than that of q,CIG complex. Finally, the nature of bond was analyzed in terms of partial charges distribution based on NBO population.
文摘For the Na + I2 collision system, theoretical study is performed on the QCISD(T) level by using ab initio method. The ab initio potential energy surfaces are got and on them the long-lived complexes are found and optimized. These results verify the crossed molecule beam experimental phenomenon and the detailed geometry structures are given for the first time. The role of the complexes in the reaction path is also described in detail.
文摘An intense 14 MeV neutron source facility named OKTAVIAN was installed in the A15 building,Osaka University in 1981.Along the operation period,new radioisotopes with various half-life have been produced as neutron activation products in its concrete wall shield.In this work,we investigated the concrete wall in the heavy irradiation room of OKTAVIAN using gamma spectrometry method to discover the presence of radioisotope having large half-life value(long-lived radioisotope)as neutron activation products.Computational simulations were performed prior to measurement to predict the presence of long-lived radioisotopes by employing MCNP5 and FISPACT codes.A pre-calibrated Germanium detector with high energy resolution was employed to measure the concrete.Several long-lived activation products have been observed such as 152 Eu,54 Mn,65 Zn,22 Na and 60 Co.The activity of each radioisotope was derived after estimating the detector efficiency using MCNP5.As a result of the measurement and analysis,the followings are concluded:(1)Though presence of activation products represents radiological risk to everyone who performs an experimental activity in the irradiation room of the OKTAVIAN facility,the present result shows that past experiments were carried out safely without any significant additional exposure dose coming from the wall for the last 38 years.(2)The approximated total fluence of D-T neutrons to the wall was successfully estimated from the produced radioisotope,152 Eu,because it has the longest half-life of 13.5 years among the observed radioisotopes.(3)From the results of(1)and(2),it could be possible to estimate the total activity of the concrete wall in the OKTAVIAN facility,which is very essential and important information,because this would be very valuable for decommissioning or disposal of the facility in the future.
文摘The iconic image of a giant radiating dyke swarm subsequently fragmented into three pieces via supercontinental breakup was produced by Paul May in1971(see next page).That figure presented a large part of
基金supported by NSFC for Creative Research Groups (21421004)Distinguished Young Scholars (21325625)+4 种基金NSFC/China (21636002)Oriental ScholarshipFundamental Research Funds for the Central Universities (WJ1416005)Scientific Committee of Shanghai (15XD1501400)Programme of Introducing Talents of Discipline to Universities (B16017)
文摘Bulk thanks to their characteristics of being environmentally benign,easily fabricated and relatively stable,dyesensitized solar cells(DSSCs)have attracted attention over decades as a potential alternative to solar energy conversion[1].However,as L.M.Peter pointed out in 2011,'although much more is now known about the physical and chemical processes taking place during operation of the DSSCs,the exponential increase in research effort during this period has not been matched by large increases in efficiency'[2].To date,
文摘Systematization for the maintenance of buildings enables their supporting system to be more practical than before. This study aims to make the maintenance and the long-term repairs for the buildings to be easier. In Japan, 30-40-year-old buildings seem to have been planned and built with little thought about their future maintenances, which have made them very difficult to be repaired on a large scale. This is why effective management systems about dealing with the data should be strongly suggested. Since the Building Standard Law was amended on April 1, 2008, in Japan, the regular investigation and report for particular buildings are legally obligated every three years, thus a variety of useful data can be obtained through Kitakyushu City cases as well as former data personally obtained. With those data used usefully, systematization for the maintenance of the buildings will produce satisfactory results by building up a connection between those data and the long-term repair planning.
文摘<strong>Introduction</strong>.<span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> The molecular biological mechanism of the increased incidence of the various types of cancer in obesity or type 2 diabetes in rodents or humans has largely been resolved in recent years. By contrast, the molecular biological mechanism of the decreased, not increased, incidence of the various types of cancer in the homozygous long-lived Ames dwarf mice still remains unresolved. </span><b><span style="font-family:Verdana;">Objective.</span></b><span style="font-family:Verdana;"> The first objective of the present study was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the increase, not decrease, in the expression of p27Kip1, a cell cycle repressor protein. The second objective was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the decrease, not increase, in the levels of glucose or insulin. </span><b><span style="font-family:Verdana;">Methods.</span></b><span style="font-family:Verdana;"> To achieve these objectives, we first performed western immunoblot analysis of the hepatic expression of p27Kip1 protein. We then performed, using a human breast cancer cell line </span><i><span style="font-family:Verdana;">in</span></i> <i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;">, the luciferase reporter plasmid assay to determine whether the translation initiation activity of the p27Kip1 mRNA is increased when the concentrations of either glucose or insulin are decreased. </span><b><span style="font-family:Verdana;">Results and Conclusion. </span></b><span style="font-family:Verdana;">The results of the first objective indicated that the hepatic expression of p27Kip1 protein was up-regulated in the homozygous long-lived Ames dwarf mice as expected. We also found that the lower concentrations of glucose or insulin increased the translation initiation activity of the p27Kip1 mRNA.</span></span></span></span>
基金The project cartied OHt under IAEA Research Agreement No 5060/CF
文摘A summary is given on the activation cross section measurements performed byChina Institute of Atomic Energy(CIAE),Lanzhou University(LU),Peking University(PU)and Sichuan University(SU)from 1989 to 1994 for generation of long-lived radionuclides of im-portance in fusion reactor technology.The cross sections are measured for the reactions <sup>109</sup>Ag(n,2n)<sup>108</sup>Ag<sup>m</sup>,<sup>151</sup>Eu(n,2n)<sup>150</sup>Eu<sup>m</sup>,<sup>153</sup>Eu(n,2n)<sup>152</sup>Eu<sup>8</sup>,<sup>159</sup>Tb(n,2n)<sup>158</sup>Tb,<sup>179</sup>Hf(n,2n )<sup>178</sup>Hf<sup>m2</sup>,<sup>182</sup>W(n,n′α)<sup>178</sup>Hf<sup>m2</sup>,<sup>187</sup>Re(n,2n)<sup>186</sup>Re<sup>m</sup> and <sup>193</sup>Ir(n,2n)<sup>192</sup>Ir<sup>m2</sup>at 14 MeV,<sup>109</sup>Ag(n,2n)<sup>108</sup>Ag<sup>m</sup>,<sup>151</sup>Eu(n,2n)<sup>150</sup>Eu<sup>m</sup>,<sup>159</sup>Tb(n,2n)<sup>158</sup>Tb and <sup>179</sup>Hf(n,2n)<sup>178</sup>Hf<sup>m2</sup>at 9.5 and 9.9 MeV,and<sup>98</sup>Mo(n,γ)<sup>199</sup>Mo(β<sup>-</sup>)→<sup>99</sup>Tc,<sup>165</sup>Ho(n.γ)<sup>166</sup>Ho<sup>m</sup> and <sup>151</sup>Eu(n,γ)<sup>152</sup>Eu<sup>8</sup> in the energy range of20~1100 keV.Some of them were calculated by systematic and HFTT code,which was basedon the compound nucleus evaporation and the preequilibrium exciton model.
基金supported by the National Natural Science Foundation of China(No.11875328).
文摘Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission products.In this study,the Geant4 toolkit was used to simulate the inter-action between a deuteron beam at 500 MeV and a com-posite target composed of alternating lead-bismuth eutectic(LBE)and water.The water was used because it may be employed as a target coolant.The energy spectrum,neu-tron yield,average energy,and total energy of the emitted neutrons were calculated for different thicknesses and thickness ratios between the LBE and water.For a constant target thickness,the neutron yield increases with an increasing thickness ratio of LBE to H 2 O,while the aver-age energy of the emitted neutrons decreases with an increasing in the aforementioned thickness ratio.These two aspects support the use of a pure target,either LBE or water.However,with an increasing LBE-to-H 2 O thickness ratio,the total energy of the emitted neutrons increases and then decreases.This result supports the addition of water into the LBE target.The angular distributions of the emitted neutrons show that the rear of the target is suit-able for loading nuclear waste containing minor actinides and long-lifetime fission products.
基金supported by the Brazilian National Council of Technological and Scientific Development(CNPq)through the"ProjetoEcológico de Longa Duração Conservação e Manejo Sustentávelde Ecossistemas Florestais—Bioma Araucária e suas Transições "(1999–2009)and through a Master degree scholarship to Angela Luciana de Avila。
文摘Understanding the effects of disturbance on seed rain is critical to predict changes in forest species composition and diversity.Logging effects on seed rain in a mixed conifer-hardwood forest complex in southern Brazil were evaluated.One year of seed rain data were collected from a large-scale observational experiment in logged and protected forests and quantity and average seed size weighted by species abundance(CWM)were compared between old-growth and logged stands 55 years after logging activities.Using these data,variations in frequency of functional groups of species in the seed rain were examined to see if they could be attributed to logging.Results show that the number of seeds per trap was highly right-skewed,ranging from 13 to 12,788 seeds per trap in one year.Seed rain was affected by logging history,with seed traps in old-growth plots receiving significantly less seeds than traps in logged plots.All species included mean seed size weighted by species abundance were significantly smaller in logged than in old-growth forests.This difference persisted after the exclusion of Arawcaria a large-seeded pioneer which was intensively logged,although the difference of seed size between the two forest classes was greatly reduced.Species abundance in the seed rain differed significantly from the established tree community,between logged and oldgrowth stands.The composition of the seed rain was much more variable than the composition of the established tree community and its points more scattered over the ordination space than the points corresponding to the protected forests.The number of collected seeds across different functional groups of species significantly differed between logged and old-growth plots.The seed rain of logged forests reflects their arrested succes sion as indicated by reduced abundance of functional groups such as pioneers,large seeded pioneers and A raucaria,as well as reduced functional diversity.S eed rain differences between logged and old-growth stands reflect the intensive logging of A.angustifolia.
基金supported by the National Magnetic Confinement Fusion Program of China (No. 2019YFE03050004)National Natural Science Foundation of China (Nos.11875253,11775221,51821005 and 11875018)+2 种基金the Fundamental Research Funds for the Central Universities (Nos.WK3420000004 and 2019kfyXJJS193)the Collaborative Innovation Program of Hefei Science Center,CAS (No. 2019HSC-CIP015)the U S Department of Energy (Nos.DEFG02-86ER53218 and DE-SC0018001)
文摘In the presence of energetic particles(EPs),the long-lived mode(LLM) frequency multiplication with n=1,2,3,or higher is often observed on HL-2A,where n is the toroidal mode number.Hybrid kinetic-MHD model simulations of the energetic particle(EP) driven kink/fishbone modes on a static HL-2A-like tokamak using NIMROD code find that when the background plasma pressure is relatively high,and the EP pressure and the beam energy are relatively low,the mode frequency increases almost linearly with EP pressure,and the frequency is proportional to n(’frequency multiplication’),even in the absence of any equilibrium plasma rotation.In addition,the frequency multiplication persists as the safety factor at the magnetic axis q_(0)varies.In the absence of EPs,the growth rate of the 1/1 mode is the largest;however,as the EP pressure increases,the growth rate of 2/2 modes or 3/3 modes becomes dominant,suggesting that higher-n modes are more vulnerable to EPs.These results may shed light on the understanding of the toroidal mode number dependence of kink/fishbone modes in the advanced scenarios of tokamaks with weak or reversed central magnetic shear.
基金The authors greatly acknowledge the Natural Science Foundation of Jiangsu Province(No.BK20220351)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.22KJB150027)for financial support.
文摘Carbon dots(CDs)with room-temperature phosphorescence(RTP)have attracted dramatically growing interest in optical functional materials.However,the photoluminescence mechanism of CDs is still a vital and challenging topic.In this work,we prepared CD-based RTP materials via melting boric acid with various lengths of alkyl amine compounds as precursors.The spatial effect on the structure and the RTP properties of CDs were systematically investigated.With the increase in carbon chain length,the interplanar spacing of the carbon core expands and crosslink-enhanced emission weakens,resulting in a decrease in the phosphorescence intensity and lifetimes.Meanwhile,based on triplet-to-singlet resonance energy transfer,we employed intense and long-lived phosphorescence CDs as the donor and short-lived fluorescent dyes as the acceptor to achieve long-lived multicolor afterglow.By the triplet-to-singlet resonance energy transfer,the afterglow color can change from green to orange.The afterglow lifetimes are more than 0.9 s.Thanks to the outstanding afterglow properties,the composites were used for timeresolved and multiple-color advanced anticounterfeiting.This work will promote the design of multicolor and long-lived afterglow materials and expand their applications.
文摘The cross section for <sup>108</sup>Cd(n,p)<sup>108</sup>Ag<sup>m</sup> reaction is measured by the activationmethod at an incident neutron energy of 14.6±0.2MeV.The result is 18.1±3.3mb.
基金IAEA project under Research Agreement No.5060/CF.
文摘The cross sections of long-lived radionuclides of importance in fusionreactor technology are measured by activation method for <sup>137</sup>Ba(n,p)<sup>137</sup>Cs,<sup>182</sup>W(n,n’x)<sup>178</sup>Hf<sup>m2</sup> and <sup>193</sup>Ir(n,2n)<sup>192</sup>Ir<sup>m2</sup> reactions at 14 MeV.The neutron fluencesare determined by the cross sections of <sup>93</sup>Nb(n,2n)<sup>92</sup>Nb<sup>m</sup>,<sup>54</sup>Fe(n,x)<sup>51</sup>Cr and<sup>54</sup>Fe(n,p)<sup>54</sup>Mn reactions.The induced gamma ray activities of the irradiated Ba<sub>2</sub>O<sub>3</sub>,Wand Ir samples and their monitor foils are measured by a calibrated Ge(Li)detector oran anti-Compton gamma ray spectrometer.
文摘The cross sections for the formation of long-lived products <sup>108</sup>Ag<sup>m</sup>(6<sup>+</sup>,433a),<sup>150</sup>Eu<sup>m</sup>(5<sup>-</sup>,36.9a),<sup>158</sup>Tb(3<sup>-</sup>,180a)and <sup>178</sup>Hf<sup>m2</sup>(16<sup>+</sup>,31a)are measured in the(n,2n)reaction on the elementsof <sup>109</sup>Ag,<sup>151</sup>Eu,<sup>159</sup>Tb and <sup>79</sup>Hf at neutron energies of 9.5 MeV and 0.9 MeV,respectively.The neu-tron fluence is obtained through the <sup>197</sup>Au(n,2n)<sup>196</sup>Au reaction.The D(d,n)<sup>3</sup>He reaction is used as neu-tron source at the tandem accelerator.The present results are compared with the averaged values of theo-retical cross sections and the experimental data.