Elucidating the mutual effects between the different volatile organic compounds(VOCs)is crucial for comprehending the formation mechanism of atmospheric secondary organic aerosols(SOA).Here,the mixed VOCs experiments ...Elucidating the mutual effects between the different volatile organic compounds(VOCs)is crucial for comprehending the formation mechanism of atmospheric secondary organic aerosols(SOA).Here,the mixed VOCs experiments of isoprene and△^(3)-carene/β-caryophyllene were carried out in the presence of O_(3)using an indoor smog chamber.The suppression effect of isoprene was recognized by the scanning mobility particle sizer spectrometer,online vacuum ultraviolet free electron laser(VUV-FEL)photoionization aerosol mass spectrometry,and quantum chemical calculations.The results indicate that the suppression effect of isoprene on the ozonolysis of△^(3)-carene andβ-caryophyllene shows fluctuating and monotonous trends,respectively.The carbon content of the precursor could be themain factor for regulating the strength of the suppression effect.Plausible structures and formation mechanisms of several new products generated from the single VOC precursor and VOC-cross-reaction are proposed,which enrich the category of VOC oxidation products.Meanwhile,a new dimerization mechanism of the RO_(2)+R’O_(2)reaction is suggested,which offers an intriguing perspective on the gas phase formation process of particle phase accretion products.The present findings provide valuable insights into clarifying the pivotal roles played by isoprene in the interplay between different VOCs and understanding of SOA formation mechanisms of VOC mixtures,especially nearby the emission origins.展开更多
A simple Cu（OAc）2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired ...A simple Cu（OAc）2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired products in moderate to excellent yields, using Cu（OAc）2 as the catalyst and Et3N as the solvent.展开更多
Three types of ligands have been developed for copper-catalyzed Ullmann cross coupling reaction of bromaminic acid with amines in aqueous solution. Ligands with large steric hindrance and strong electron-donating capa...Three types of ligands have been developed for copper-catalyzed Ullmann cross coupling reaction of bromaminic acid with amines in aqueous solution. Ligands with large steric hindrance and strong electron-donating capacity were beneficial to the reaction. UV–Vis and CV analyses demonstrated that these ligands had strong coordination with copper(I), implying the effect of ligand coordination ability on the stability and catalytic activity of catalytic system.展开更多
In this study, the activation cross-sections were measured for ^(232)Th(n,2n)^(231)Th reactions at neutron energies of 14.1 and 14.8 MeV, which were produced by a neutron generator through a T(d,n)~4He reaction. Induc...In this study, the activation cross-sections were measured for ^(232)Th(n,2n)^(231)Th reactions at neutron energies of 14.1 and 14.8 MeV, which were produced by a neutron generator through a T(d,n)~4He reaction. Induced gamma-ray activities were measured using a low background gamma ray spectrometer equipped with a high resolution HPGe detector. In the cross-section calculations, corrections were made regarding the effects of gamma-ray attenuation, dead-time, fluctuation of the neutron flux, and low energy neutrons. The measured cross-sections were compared with the literature data, evaluation data(ENDF-B/VII.1, JENDL-4.0 and CENDL-3.1), and the results of the model calculation(TALYS1.6).展开更多
Highly active, air-stable and water-soluble palladium-phosphinous acid complexes have been applied to Suzuki cross-coupling reaction of heteroaryl bromides under mild conditions in water/alcoholic solvents. Suzuki cro...Highly active, air-stable and water-soluble palladium-phosphinous acid complexes have been applied to Suzuki cross-coupling reaction of heteroaryl bromides under mild conditions in water/alcoholic solvents. Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid occurred efficiently using palladium phosphinous acid complexes （POPd） and phase transfer catalyst （tetrabutylammonium bromide and polyethylene glycol） in water/ethanol mixture, water/propanol mixture and neat water respectively, the corresponding yields of cross-coupling heteroaryl-aryls were satisfied. The tert-butyl substituted ligand di-tert-butylphosphino in combination with POPd was found to be more active than the same family derived catalysts dipalladium complexes POPdl and POPd2, and other two kinds of Pd-catalysts Pd（PPh3）4 and Pd2（dba）3. The mechanism of Suzuki cross-coupling reaction between heteroaryl bromides and phenylboronic acid in water was proposed with respect to the key role of phase transfer catalyst on the transmetallation step. Compared with other solid phase transfer catalysts, TBAB was tested as the ideal one. The alkalinity of base and the molar proportion between POPd and TBAB were investigated in water and alcoholic solvents. Notably, in the presence of TBAB adding alcoholic solvents into water enhanced the yields of target products. However in terms of the liquid phase transfer catalyst of PEGs, mixing water into PEGs could slightly decrease the yields with respect to the water free PEGs bulk phase, which was probably due to the homogenous liquid conditions in pure PEGs and weak interactions between PEGs and heteroaryl bromide molecules in water depending on their molecular chain lengths.展开更多
The present paper deals with the polymerization of ( R ) 3,3′ diiodo 2,2′ binaphtho 20 crown 6 with \{ p divinylbenzene\} under Heck coupling reaction condition. Both the monomers and the polymer were analyzed by NM...The present paper deals with the polymerization of ( R ) 3,3′ diiodo 2,2′ binaphtho 20 crown 6 with \{ p divinylbenzene\} under Heck coupling reaction condition. Both the monomers and the polymer were analyzed by NMR, FTIR, UV, CD, fluorescent spectroscopy, polarimetry, GPC and elemental analysis. The polymer can emit a strong blue fluorescence and is expected to have the potential application in the polarized blue light emitting sensors. The chiral conjugated polymer exhibits a strong Cotton effect in its Circular Dichroism(CD ) spectrum, indicating the high rigidity of the polymer backbone.展开更多
Pyrazoles and their derivatives are important heterocycles found in nature and present in numerous bioactive compounds.In contrast to 3 or 5-aryl pyrazole,the preparation of 4-aryl pyrazole is fairly rare.Utilizing mi...Pyrazoles and their derivatives are important heterocycles found in nature and present in numerous bioactive compounds.In contrast to 3 or 5-aryl pyrazole,the preparation of 4-aryl pyrazole is fairly rare.Utilizing microwave irradiation,the synthesis of 4-substituted-arylpyrazole via Suzuki cross-coupling has been developed with a wide range of substrates.The remarkable advantages of this method are mild reaction conditions,simple operation,high yield,and short reaction time.Product structures were identified by MS 1H NMR 13C NMR,and elemental analysis.展开更多
A subgroup of coeliac disease patients continues to experience symptoms even on a gluten-free diet (GFD). We attempted to determine whether these symptoms could be due to either cross-contamination with gluten-contain...A subgroup of coeliac disease patients continues to experience symptoms even on a gluten-free diet (GFD). We attempted to determine whether these symptoms could be due to either cross-contamination with gluten-containing foods or cross-reactivity between α-gliadin and non-gluten foods consumed on a GFD. We measured the reactivity of affinity-purified polyclonal and monoclonal α-gliadin 33-mer peptide antibodies against gliadin and additional food antigens commonly consumed by patients on a GFD using ELISA and dot-blot. We also examined the immune reactivity of these antibodies with various tissue antigens. We observed significant immune reactivity when these antibodies were applied to cow’s milk, milk chocolate, milk butyrophilin, whey protein, casein, yeast, oats, corn, millet, instant coffee and rice. To investigate whether there was cross-reactivity between α-gliadin antibody and different tissue antigens, we measured the degree to which this antibody bound to these antigens. The most significant binding occurred with asialoganglioside, hepatocyte, glutamic acid decarboxylase 65, adrenal 21-hydroxylase, and various neural antigens. The specificity of anti-α-gliadin binding to different food and tissue antigens was demonstrated by absorption and inhibition studies. We also observed significant cross-reactivity between α-gliadin 33-mer and various food antigens, but some of these reactions were associated with the contamination of non-gluten foods with traces of gluten. The consumption of cross-reactive foods as well as gluten-contaminated foods may be responsible for the continuing symptoms presented by a subgroup of patients with coeliac disease. The lack of response of some CD patients may also be due to antibody cross-reactivity with non-gliadin foods. These should then be treated as gluten-like peptides and should also be excluded from the diet when the GFD seems to fail.展开更多
Cross-sections of the(n,2n) reactions for neodymium(Nd) isotopes induced by 14 MeV neutrons were measured in this work by using the activation and relative methods. The measured cross-sections of the ^(150)Nd(n,2n)^(1...Cross-sections of the(n,2n) reactions for neodymium(Nd) isotopes induced by 14 MeV neutrons were measured in this work by using the activation and relative methods. The measured cross-sections of the ^(150)Nd(n,2n)^(149)Nd,^(148)Nd(n,2n)^(147)Nd, and ^(142)Nd(n,2 n)^(141)Nd reactions were 1854 ± 81, 1789 ± 119, and 1559 ± 98 mb, respectively, at a neutron energy of 14.2 ± 0.2 MeV,and 1485 ± 74, 1726 ± 85, and 1670 ± 119 mb, respectively, at 14.9 ± 0.2 MeV. The results were compared with the experimental values from the reported literature, with the evaluated data from the ENDF/B-VII.1, CENDL-3.1, and JENDL-4.0 libraries, and with the curves calculated by the Talys-1.8 code.展开更多
Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some im...Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.展开更多
The cross sections for the^(63)Cu(n,a)^(60(m+g))Co,^(65)Cu(n,2 n)^(64)Cu, and ^(65)Cu(n,p)^(65)Ni reactions have been studied in the neutron energy range of 13.5–14.8 MeV using the activation technique. The neutron b...The cross sections for the^(63)Cu(n,a)^(60(m+g))Co,^(65)Cu(n,2 n)^(64)Cu, and ^(65)Cu(n,p)^(65)Ni reactions have been studied in the neutron energy range of 13.5–14.8 MeV using the activation technique. The neutron beams were produced via the^3 H(d,n)~4 He reaction. The neutron energies of different directions in the measurements were determined beforehand by the method of cross section ratios for the^(90)Zr(n,2 n)^(89 m+g)Zr and ^(93)Nb(n,2 n)^(92 m)Nb reactions. The results in the present work were discussed and compared with measurement results found in the literatures.展开更多
We studied the structure of 12 C through the modified Glauber model using the density distributions calculated by the relativistic mean field theory. The experimental reaction cross sections of 12 C + 12 C were analyz...We studied the structure of 12 C through the modified Glauber model using the density distributions calculated by the relativistic mean field theory. The experimental reaction cross sections of 12 C + 12 C were analyzed within the MOL by a χ 2 -fitting procedure. The effects of the nuclear deformation on the reaction cross sections are studied. The reliable structure of 12 C is deduced. The studies show that the conjunction of these two models will be a more effective tool to study the properties of nuclei.展开更多
In this work, the reaction cross-section for neutron-induced reactions on 127I isotope was calculated using EXIFON code in the energy range of incident particle from 0 MeV to 30 MeV. The code is based on an analytical...In this work, the reaction cross-section for neutron-induced reactions on 127I isotope was calculated using EXIFON code in the energy range of incident particle from 0 MeV to 30 MeV. The code is based on an analytical model for statistical multistep direct and multistep compound reactions (SMD/SMC model). In order to see the effect of nuclear structure on cross sections, the calculation was done using nuclear shell structure effect and without considering shell structure effect. Obtained results and statistical analysis showed that shell structure effect does not give significant changes to the cross-section at considered energy ranges. This shows that EXIFON code is a good tool for investigation of nuclear reaction cross section and is useful in the production of the radioisotopes of Iodine, Antimony and tellurium of high purity and in an efficient manner using cyclotron or nuclear reactors, these isotopes have potential application for field of medical science especially for diagnostics and therapeutic purposes.展开更多
Two independent measurements of cross sections for the 19F+93Nb dissipative heavy-ion collision (DHIC) have been performed at incident energies from 100 to 108 MeV in steps of 250 keV. Two independently prepared targe...Two independent measurements of cross sections for the 19F+93Nb dissipative heavy-ion collision (DHIC) have been performed at incident energies from 100 to 108 MeV in steps of 250 keV. Two independently prepared targets were used respectively with all other experimental conditions being identical in both experiments. The data indicate non-reproducibility of the non-self-averaging oscillation yields in the two measurements. The statistical analysis of this non-reproducibility supports recent theoretical predictions of spontaneous coherence, slow phase randomization and extreme sensitivity in highly excited quantum many-body systems.展开更多
On the basis of Hauser-Feshbach theory and some approximations,parametrized formulae of isomeric cross section ratio including two adjustableparameters for(n,t)reaction at 14.6MeV are derived.By fitting these formulae...On the basis of Hauser-Feshbach theory and some approximations,parametrized formulae of isomeric cross section ratio including two adjustableparameters for(n,t)reaction at 14.6MeV are derived.By fitting these formulae to theavailable measured data,parameters are obtained and the systematic behaviour of theisomeric cross section ratio are studied.The isomeric cross section ratio predicted by thepresent work is in good agreement with the limited measured data.展开更多
-The energy spectrum and angular distributions of protons from <sup>93</sup>Nb（n,xp）reactions are measured by means of the USTC（University of Science and Technologyof China）multitelescope system.The to...-The energy spectrum and angular distributions of protons from <sup>93</sup>Nb（n,xp）reactions are measured by means of the USTC（University of Science and Technologyof China）multitelescope system.The total proton production cross sections are in fairagreement with the results of other groups.The energy spectrum is well explained by thesum of the spectra calculated on the basis of the preequilibrium and the H-F theories.Deviations from the previous measurement at the high energy end of the angle-inte-grated proton spectrum are found.The angular distributions which show a stronglyenergy-dependent forward-backward asymmetry are in fair agreement with thephenomenological model of Kalbach-Mann.展开更多
In this work, new cross section formulae for (n, p) and (n, d) reactions of He-3 have been investigated as a function of incident neutron energy. The new Empirical formulae were produced by using the least squares met...In this work, new cross section formulae for (n, p) and (n, d) reactions of He-3 have been investigated as a function of incident neutron energy. The new Empirical formulae were produced by using the least squares method to the experimental cross sections data, which were taken from Experimental Nuclear Reaction Data EXFOR Database Version of 2021. Several functions were examined to choose the best one that fits the data. Statistical hypothesis testing was used to insure how well the suggested equations fit the set of data. Two statistical indicators were used for each case for goodness-of-fit. Very high compatibility was found between the empirical values and the experimental data for both reactions.展开更多
The quasi-classical trajectory calculation for the reaction O（^1D）＋HD is carried out based on the Dobbyn and Knowles potential energy surface. In this work, the reaction cross section and product branching ratio ar...The quasi-classical trajectory calculation for the reaction O（^1D）＋HD is carried out based on the Dobbyn and Knowles potential energy surface. In this work, the reaction cross section and product branching ratio are obtained. The product branching ratio OD/OH was discussed. The calculated results show that the cross-section decreases thoroughly with the increasing of the collision energy from 4.6 kJ/mol to 46.0 kJ/mol. The average branching ratio decrease with the increase of rotational quantum number of reactant HD.展开更多
基金supported by the National Natural Science Foundation of China(Nos.92361302,22125303,92061203,and 22288201)the National Key Research and Development Program of China(No.2021YFA1400501)+2 种基金the Innovation Program for Quantum Science and Technology(No.2021ZD0303304)Dalian Institute of Chemical Physics(No.DICP DCLS201702)Chinese Academy of Sciences(No.GJJSTD20220001).
文摘Elucidating the mutual effects between the different volatile organic compounds(VOCs)is crucial for comprehending the formation mechanism of atmospheric secondary organic aerosols(SOA).Here,the mixed VOCs experiments of isoprene and△^(3)-carene/β-caryophyllene were carried out in the presence of O_(3)using an indoor smog chamber.The suppression effect of isoprene was recognized by the scanning mobility particle sizer spectrometer,online vacuum ultraviolet free electron laser(VUV-FEL)photoionization aerosol mass spectrometry,and quantum chemical calculations.The results indicate that the suppression effect of isoprene on the ozonolysis of△^(3)-carene andβ-caryophyllene shows fluctuating and monotonous trends,respectively.The carbon content of the precursor could be themain factor for regulating the strength of the suppression effect.Plausible structures and formation mechanisms of several new products generated from the single VOC precursor and VOC-cross-reaction are proposed,which enrich the category of VOC oxidation products.Meanwhile,a new dimerization mechanism of the RO_(2)+R’O_(2)reaction is suggested,which offers an intriguing perspective on the gas phase formation process of particle phase accretion products.The present findings provide valuable insights into clarifying the pivotal roles played by isoprene in the interplay between different VOCs and understanding of SOA formation mechanisms of VOC mixtures,especially nearby the emission origins.
文摘A simple Cu（OAc）2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired products in moderate to excellent yields, using Cu（OAc）2 as the catalyst and Et3N as the solvent.
基金Supported by the National Natural Science Foundation of China(21176038,21576044,21536002)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(21421005)the Dalian University of Technology Innovation Team(DUT2013TB07)
文摘Three types of ligands have been developed for copper-catalyzed Ullmann cross coupling reaction of bromaminic acid with amines in aqueous solution. Ligands with large steric hindrance and strong electron-donating capacity were beneficial to the reaction. UV–Vis and CV analyses demonstrated that these ligands had strong coordination with copper(I), implying the effect of ligand coordination ability on the stability and catalytic activity of catalytic system.
基金Supported by National Natural Science Foundation of China(No.11205076)
文摘In this study, the activation cross-sections were measured for ^(232)Th(n,2n)^(231)Th reactions at neutron energies of 14.1 and 14.8 MeV, which were produced by a neutron generator through a T(d,n)~4He reaction. Induced gamma-ray activities were measured using a low background gamma ray spectrometer equipped with a high resolution HPGe detector. In the cross-section calculations, corrections were made regarding the effects of gamma-ray attenuation, dead-time, fluctuation of the neutron flux, and low energy neutrons. The measured cross-sections were compared with the literature data, evaluation data(ENDF-B/VII.1, JENDL-4.0 and CENDL-3.1), and the results of the model calculation(TALYS1.6).
基金supported by the Natural Science Foundation of Liaoning Education Department (No. 2008T094)
文摘Highly active, air-stable and water-soluble palladium-phosphinous acid complexes have been applied to Suzuki cross-coupling reaction of heteroaryl bromides under mild conditions in water/alcoholic solvents. Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid occurred efficiently using palladium phosphinous acid complexes （POPd） and phase transfer catalyst （tetrabutylammonium bromide and polyethylene glycol） in water/ethanol mixture, water/propanol mixture and neat water respectively, the corresponding yields of cross-coupling heteroaryl-aryls were satisfied. The tert-butyl substituted ligand di-tert-butylphosphino in combination with POPd was found to be more active than the same family derived catalysts dipalladium complexes POPdl and POPd2, and other two kinds of Pd-catalysts Pd（PPh3）4 and Pd2（dba）3. The mechanism of Suzuki cross-coupling reaction between heteroaryl bromides and phenylboronic acid in water was proposed with respect to the key role of phase transfer catalyst on the transmetallation step. Compared with other solid phase transfer catalysts, TBAB was tested as the ideal one. The alkalinity of base and the molar proportion between POPd and TBAB were investigated in water and alcoholic solvents. Notably, in the presence of TBAB adding alcoholic solvents into water enhanced the yields of target products. However in terms of the liquid phase transfer catalyst of PEGs, mixing water into PEGs could slightly decrease the yields with respect to the water free PEGs bulk phase, which was probably due to the homogenous liquid conditions in pure PEGs and weak interactions between PEGs and heteroaryl bromide molecules in water depending on their molecular chain lengths.
文摘The present paper deals with the polymerization of ( R ) 3,3′ diiodo 2,2′ binaphtho 20 crown 6 with \{ p divinylbenzene\} under Heck coupling reaction condition. Both the monomers and the polymer were analyzed by NMR, FTIR, UV, CD, fluorescent spectroscopy, polarimetry, GPC and elemental analysis. The polymer can emit a strong blue fluorescence and is expected to have the potential application in the polarized blue light emitting sensors. The chiral conjugated polymer exhibits a strong Cotton effect in its Circular Dichroism(CD ) spectrum, indicating the high rigidity of the polymer backbone.
基金the National Nature Science Foundation of China (Nos. 21002038 and 21272091) for the financial support
文摘Pyrazoles and their derivatives are important heterocycles found in nature and present in numerous bioactive compounds.In contrast to 3 or 5-aryl pyrazole,the preparation of 4-aryl pyrazole is fairly rare.Utilizing microwave irradiation,the synthesis of 4-substituted-arylpyrazole via Suzuki cross-coupling has been developed with a wide range of substrates.The remarkable advantages of this method are mild reaction conditions,simple operation,high yield,and short reaction time.Product structures were identified by MS 1H NMR 13C NMR,and elemental analysis.
文摘A subgroup of coeliac disease patients continues to experience symptoms even on a gluten-free diet (GFD). We attempted to determine whether these symptoms could be due to either cross-contamination with gluten-containing foods or cross-reactivity between α-gliadin and non-gluten foods consumed on a GFD. We measured the reactivity of affinity-purified polyclonal and monoclonal α-gliadin 33-mer peptide antibodies against gliadin and additional food antigens commonly consumed by patients on a GFD using ELISA and dot-blot. We also examined the immune reactivity of these antibodies with various tissue antigens. We observed significant immune reactivity when these antibodies were applied to cow’s milk, milk chocolate, milk butyrophilin, whey protein, casein, yeast, oats, corn, millet, instant coffee and rice. To investigate whether there was cross-reactivity between α-gliadin antibody and different tissue antigens, we measured the degree to which this antibody bound to these antigens. The most significant binding occurred with asialoganglioside, hepatocyte, glutamic acid decarboxylase 65, adrenal 21-hydroxylase, and various neural antigens. The specificity of anti-α-gliadin binding to different food and tissue antigens was demonstrated by absorption and inhibition studies. We also observed significant cross-reactivity between α-gliadin 33-mer and various food antigens, but some of these reactions were associated with the contamination of non-gluten foods with traces of gluten. The consumption of cross-reactive foods as well as gluten-contaminated foods may be responsible for the continuing symptoms presented by a subgroup of patients with coeliac disease. The lack of response of some CD patients may also be due to antibody cross-reactivity with non-gliadin foods. These should then be treated as gluten-like peptides and should also be excluded from the diet when the GFD seems to fail.
文摘Cross-sections of the(n,2n) reactions for neodymium(Nd) isotopes induced by 14 MeV neutrons were measured in this work by using the activation and relative methods. The measured cross-sections of the ^(150)Nd(n,2n)^(149)Nd,^(148)Nd(n,2n)^(147)Nd, and ^(142)Nd(n,2 n)^(141)Nd reactions were 1854 ± 81, 1789 ± 119, and 1559 ± 98 mb, respectively, at a neutron energy of 14.2 ± 0.2 MeV,and 1485 ± 74, 1726 ± 85, and 1670 ± 119 mb, respectively, at 14.9 ± 0.2 MeV. The results were compared with the experimental values from the reported literature, with the evaluated data from the ENDF/B-VII.1, CENDL-3.1, and JENDL-4.0 libraries, and with the curves calculated by the Talys-1.8 code.
基金supported by the Saint Petersburg Mining University
文摘Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.
基金supported by the National Natural Science Foundation of China(Nos.11575090 and 11605099)the Young Key Teachers Training Porgram of He’nan Higher Education in China(No.2015GGJS-258)
文摘The cross sections for the^(63)Cu(n,a)^(60(m+g))Co,^(65)Cu(n,2 n)^(64)Cu, and ^(65)Cu(n,p)^(65)Ni reactions have been studied in the neutron energy range of 13.5–14.8 MeV using the activation technique. The neutron beams were produced via the^3 H(d,n)~4 He reaction. The neutron energies of different directions in the measurements were determined beforehand by the method of cross section ratios for the^(90)Zr(n,2 n)^(89 m+g)Zr and ^(93)Nb(n,2 n)^(92 m)Nb reactions. The results in the present work were discussed and compared with measurement results found in the literatures.
文摘We studied the structure of 12 C through the modified Glauber model using the density distributions calculated by the relativistic mean field theory. The experimental reaction cross sections of 12 C + 12 C were analyzed within the MOL by a χ 2 -fitting procedure. The effects of the nuclear deformation on the reaction cross sections are studied. The reliable structure of 12 C is deduced. The studies show that the conjunction of these two models will be a more effective tool to study the properties of nuclei.
文摘In this work, the reaction cross-section for neutron-induced reactions on 127I isotope was calculated using EXIFON code in the energy range of incident particle from 0 MeV to 30 MeV. The code is based on an analytical model for statistical multistep direct and multistep compound reactions (SMD/SMC model). In order to see the effect of nuclear structure on cross sections, the calculation was done using nuclear shell structure effect and without considering shell structure effect. Obtained results and statistical analysis showed that shell structure effect does not give significant changes to the cross-section at considered energy ranges. This shows that EXIFON code is a good tool for investigation of nuclear reaction cross section and is useful in the production of the radioisotopes of Iodine, Antimony and tellurium of high purity and in an efficient manner using cyclotron or nuclear reactors, these isotopes have potential application for field of medical science especially for diagnostics and therapeutic purposes.
基金Supported by the Natural Science Foundation of China(No.19775057 and No.10175083)the Major State Basic Research De-velopment(G2000077401)
文摘Two independent measurements of cross sections for the 19F+93Nb dissipative heavy-ion collision (DHIC) have been performed at incident energies from 100 to 108 MeV in steps of 250 keV. Two independently prepared targets were used respectively with all other experimental conditions being identical in both experiments. The data indicate non-reproducibility of the non-self-averaging oscillation yields in the two measurements. The statistical analysis of this non-reproducibility supports recent theoretical predictions of spontaneous coherence, slow phase randomization and extreme sensitivity in highly excited quantum many-body systems.
文摘On the basis of Hauser-Feshbach theory and some approximations,parametrized formulae of isomeric cross section ratio including two adjustableparameters for(n,t)reaction at 14.6MeV are derived.By fitting these formulae to theavailable measured data,parameters are obtained and the systematic behaviour of theisomeric cross section ratio are studied.The isomeric cross section ratio predicted by thepresent work is in good agreement with the limited measured data.
基金The project supported in part by National Natural Science Foundation of China and CNNC
文摘-The energy spectrum and angular distributions of protons from <sup>93</sup>Nb（n,xp）reactions are measured by means of the USTC（University of Science and Technologyof China）multitelescope system.The total proton production cross sections are in fairagreement with the results of other groups.The energy spectrum is well explained by thesum of the spectra calculated on the basis of the preequilibrium and the H-F theories.Deviations from the previous measurement at the high energy end of the angle-inte-grated proton spectrum are found.The angular distributions which show a stronglyenergy-dependent forward-backward asymmetry are in fair agreement with thephenomenological model of Kalbach-Mann.
文摘In this work, new cross section formulae for (n, p) and (n, d) reactions of He-3 have been investigated as a function of incident neutron energy. The new Empirical formulae were produced by using the least squares method to the experimental cross sections data, which were taken from Experimental Nuclear Reaction Data EXFOR Database Version of 2021. Several functions were examined to choose the best one that fits the data. Statistical hypothesis testing was used to insure how well the suggested equations fit the set of data. Two statistical indicators were used for each case for goodness-of-fit. Very high compatibility was found between the empirical values and the experimental data for both reactions.
文摘The quasi-classical trajectory calculation for the reaction O（^1D）＋HD is carried out based on the Dobbyn and Knowles potential energy surface. In this work, the reaction cross section and product branching ratio are obtained. The product branching ratio OD/OH was discussed. The calculated results show that the cross-section decreases thoroughly with the increasing of the collision energy from 4.6 kJ/mol to 46.0 kJ/mol. The average branching ratio decrease with the increase of rotational quantum number of reactant HD.
