Oxygen carriers play a fundamental role in chemical looping combustion(CLC).Iron-based carriers have been extensively investigated owing to their abundance and environmentally friendly.However,the reactivity and separ...Oxygen carriers play a fundamental role in chemical looping combustion(CLC).Iron-based carriers have been extensively investigated owing to their abundance and environmentally friendly.However,the reactivity and separability of iron-based carriers require further enhancement.This study investigates the effect of the concentration of Mn doping on reactivity,elastic properties and magnetic properties based on density functional theory(DFT)calculations.Theoretical results demonstrate that Mn doping effectively enhances reactivity by reducing the oxygen vacancy formation energy(E_(vac))from 2.33 to 0.87 eV.However,Mn doping introduces HV/EV Ms lattice distortions that deteriorate elastic properties,thereby reducing wear resistance,as evidenced by a 54.54%decrease in the hardness-to-Young's modulus ratio(H_(v)/E_(v))forα-Fe_(2)O_(3)and an 83.33%reduction for Fe_(3)O_(4).Furthermore,Mn doping also modifies magnetic properties.The maximum of saturation magnetization(M_(s))of Fe_(3)O_(4)reaches 121.02 emu/g at 33.33%Mn doping concentration.Finally,systematic evaluation identifies 33.33%as the optimal Mn doping concentration,achieving a balance in enhanced reactivity,superior magnetic performance,and retained elastic stability.展开更多
Knowing the precise relationship between fuel loading and reactivity is essential for guiding reactor criticality extrapolation and online refueling in molten salt reactors(MSRs).This study aims to explore and explain...Knowing the precise relationship between fuel loading and reactivity is essential for guiding reactor criticality extrapolation and online refueling in molten salt reactors(MSRs).This study aims to explore and explain the linear relationship between reactivity and the reciprocal of uranium concentration in thermal-spectrum MSRs.By applying neutron balance theory,we analyzed the neutron absorption cross sections of various nuclides in single-lattice models with varying fuel concentrations.Our findings reveal a simple linear correlation between reactivity and the reciprocal of uranium concentration,which can be explained from the perspective of nuclear reaction cross sections that adhere to the 1/v law in the thermal neutron spectrum.Furthermore,we identified that the neutron absorption single-group cross sections of structural materials and carrier salts exhibit an approximately linear relationship with the fission single-group cross section of ^(235) U;similarly,the reciprocal of ^(235)U’s fission cross section exhibits an approximately linear relationship with uranium concentration.This linear relationship deviates as the volume fraction of molten salt increases,due to a greater proportion of neutrons being captured in the resonance energy spectrum.However,it remains valid for molten salt volume fractions up to 25%and demonstrates broad applicability in the physical design and operation of thermal molten salt reactors.展开更多
Tetrasodium iminodisuccinate(IDS)was used as an inhibitor in the separation of sphalerite and pyrite in the EX−Cu(II)(ethyl xanthate and Cu2+)system.The flotation test results demonstrated that IDS can effectively sep...Tetrasodium iminodisuccinate(IDS)was used as an inhibitor in the separation of sphalerite and pyrite in the EX−Cu(II)(ethyl xanthate and Cu2+)system.The flotation test results demonstrated that IDS can effectively separate sphalerite and pyrite under low alkaline conditions.Furthermore,high-quality zinc concentrates with a Zn grade of 58.48%and a recovery of 91.24%through mixed mineral flotation were obtained.The fundamental mechanisms were investigated through surface wettability tests,adsorption capacity tests,LEIS,FTIR,and XPS.The results confirmed that IDS prevents the adsorption of EX on the surface of pyrite,thereby reducing the response and reactivity of pyrite.The introduction of IDS causes the detachment of Cu2+from the Cu-activated pyrite surface.This process allowed IDS to chelate with the Fe sites on the surface of pyrite through the-COO-and N-centered active groups.By contrast,IDS exhibits weaker adhesion on the surface of Cu-activated sphalerite,making it easily displaced by EX through competitive adsorption.展开更多
The pressure and temperature increase resulting from the impact of different threats onto target materials is analyzed with a unified laboratory-scale setup.This allows deriving qualitative information on the occurrin...The pressure and temperature increase resulting from the impact of different threats onto target materials is analyzed with a unified laboratory-scale setup.This allows deriving qualitative information on the occurring phenomenology as well as quantitative statements about the relative effects sizes as a function of target material and threat.The considered target materials are steel,aluminum,and magnesium.As threats,kinetic energy penetrator,explosively formed projectile,and shaped charge jet are used.For the investigated combinations,the measured overpressures vary by a factor of up to 5 for a variation of the material,by a factor of up to 7 for a variation of the threat,and by a factor larger than 15for a simultaneous variation of both.The obtained results as well as the experimental approach are relevant for the basic understanding of impact effects and risks due to material reactivity.The paper combines two main aims.Firstly,to provide a summary of own prior work in a coherent journal article and,secondly,to review and discuss these earlier results with a new perspective.展开更多
The thermal conversion process known as biomass gasification has the potential to produce environmentally friendly fuels such as hydrogen.However,tar generation during the gasification remains an issue,affecting opera...The thermal conversion process known as biomass gasification has the potential to produce environmentally friendly fuels such as hydrogen.However,tar generation during the gasification remains an issue,affecting operational efficiency and environmental health.Biochar has been confirmed as an inexpensive and efficient catalyst for tar removal.The challenge lies in creating a highly reactive biochar which can be applied for different types of biomass with varying properties.This review discusses the factors that affect biochar’s reactivity as a catalyst for tar reforming.Additionally,incorporating biochar into a gasification scenario with raw biomass offers a practical solution by leveraging the synergistic behavior.However,this synergy could be either positive or negative:the positive synergy enhances tar removal while the negative synergy has the opposite effect.The numerous factors affecting the results of gasification are presented in this review.It is concluded that the positive synergistic effect resulted from the balance between the available reactants from biomass and biochar,the optimal gas flowrate and the active sites on the carbon surface.Understanding these interactions is crucial for optimizing biochar performance for tar removal.Ultimately,this research provides insights into biochar’s role in biomass gasification and suggests improvements for future studies to enhance the feasibility of biomass gasification with the assistance of biochar.展开更多
Aluminum(Al)powder is widely applied in thermobaric explosives due to its high energy density and favorable reaction kinetics.However,the inert oxide layer(Al_(2)O_(3))on Al particles limits combustion reactivity and ...Aluminum(Al)powder is widely applied in thermobaric explosives due to its high energy density and favorable reaction kinetics.However,the inert oxide layer(Al_(2)O_(3))on Al particles limits combustion reactivity and energy efficiency.Fluoride-based surface modification has been developed as an effective approach to address this issue.Here,four classical fluoropolymers(F11,F14,PVDF,PTFE)are employed as coatings to prepare core-shell Al/Fluoropolymer.The combustion experimental results demonstrate that the core-shell Al/PTFE exhibits the highest flame propagation rate(52.88 mm·ms^(-1))and pressure output(109.02 k Pa)performance.Consequently,core-shell Al/PTFE is selected as a high-energy fuel to prepare RDX/Al/PTFE microspheres via the emulsion and solvent evaporation method,which can enhance the energy performance of RDX.The effects of the core-shell Al/PTFE ratio and RDX content on the combustion heat and pressure output are systematically investigated.The peak pressure reaches a maximum of 187.8 k Pa when the mass ratio of RDX,Al,and PTFE is 60:25:10.Additionally,RDX/Al/PTFE microspheres exhibit significantly higher laser-induced air shock velocities,detonation heat,and detonation pressure than those of pure RDX and RDX/Al.The mechanism underlying the enhanced reactivity and energetic performance is attributed to the ability of PTFE to etch the inert Al_(2)O_(3)shell on the surface of Al particles,thereby improving post-combustion reactions and significantly increasing the overall energy output of RDX explosives.This work offers a novel design strategy for high-energy structural thermobaric explosives for the practical applications.展开更多
The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by fr...The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by frontier orbital methods.The cell volume expands due to the presence of impurity.Co and Ni mainly affect the bands near Fermi levels,while As mainly affects the shallow and deep valence bands,and Se and Te mainly affect the deep valence bands.Electronic density analysis suggests that there exists a strong covalent interaction between hetero atom and its surrounding atoms.By frontier orbital calculation,it is suggested that As,Co and Ni have greater influence on the HOMO and LUMO of pyrite than Se and Te.In addition,pyrite containing As,Co or Ni is easier to oxidize by oxygen than pyrite containing Se or Te,and pyrite containing Co or Ni has greater interaction with collector.These are in agreement with the observed pyrite practice.展开更多
Effect of sulfur impurity on coke reactivity was investigated by simulating petroleum coke with low-impurity pitch coke and impurities doping. And its mechanism was discussed by X-ray diffraction (XRD), scanning elect...Effect of sulfur impurity on coke reactivity was investigated by simulating petroleum coke with low-impurity pitch coke and impurities doping. And its mechanism was discussed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that sulfur has strong catalysis on both air and CO2 reactivity of coke in the case of no other impurity interference. Its catalysis is probably realized by triggering organic sulfur→H2S→SO2→COS and elemental sulfur (Sx)→SO2 and organic sulfur→H2S→COS→Sx→C2S→COS reaction systems during coke?O2 and coke?CO2 reactions, respectively, which are partly circular with functions of increasing carbon consumption and enlarging coke specific surface area.展开更多
The formations and transformations of the chemical bonds of reactants and intermediates on cata- lyst surfaces occur in conjunction with the evolution of heat during catalytic reactions. Measure- ment of this evolved ...The formations and transformations of the chemical bonds of reactants and intermediates on cata- lyst surfaces occur in conjunction with the evolution of heat during catalytic reactions. Measure- ment of this evolved heat is helpful in terms of understanding the nature of the interactions be- tween the catalyst and the adsorbed species, and provides insights into the reactivity of the catalyst. Although various techniques have previously been applied to assessments of evolved heat, direct measurements using a Tian-Calvet microcalorimeter are currently the most reliable method for this purpose. In this review, we summarize the relationship between the adsorption/reaction energetics determined by microcalorimetry and the reactivities of supported catalysts, and examine the im- portant role of microcalorimetry in understanding catalytic performance from the energetic point of view.展开更多
Various platelet function tests are currently used to identify responsiveness to antiplatelet therapy. 176 ACS patients were enrolled and Linear regression and Kappa consistency analysis showed there was a significant...Various platelet function tests are currently used to identify responsiveness to antiplatelet therapy. 176 ACS patients were enrolled and Linear regression and Kappa consistency analysis showed there was a significant but moderate correlation between platelet inhibition rate and a significant but fair agreement between high clopidogrel on-treatment platelet reactivity tested by light transmission aggregometry and thrombelastography.展开更多
Objectives:We sought to determine whether high posttreatment platelet reactivity(HPPR)to a 600 mg loading dose of clopidogrel affects outcomes in Chinese patients with acute coronary syndrome(ACS)following percutaneou...Objectives:We sought to determine whether high posttreatment platelet reactivity(HPPR)to a 600 mg loading dose of clopidogrel affects outcomes in Chinese patients with acute coronary syndrome(ACS)following percutaneous coronary intervention(PCI)and to investigate whether there is a relationship between the number of platelet reactivity units(PRUs)and the characteristics of the patients.Background:Although impaired platelet response to clopidogrel is a strong predictor of unfavorable outcome after PCI,the impact of HPPR to a 600 mg loading dose of clopidogrel in Chinese patients with ACS undergoing PCI is still unknown.Methods:We performed observational research on 134 unselected patients with ACS undergoing urgent or planned PCI with a 600 mg loading dose of clopidogrel.Platelet activation was expressed as the PRU value measured by the VerifyNow assay.Results:Among the 134 patients(mean age 60.62 years[standard deviation 9.13 years],60.4%male),there were 46 patients with HPPR(34.3%)and 88 patients without HPPR(65.7%).At a mean follow-up of 6 months(standard deviation 1 month),the rates of cardiac death,unstable angina,and rehospitalization for target lesion revascularization were higher in the HPPR group(19.6%vs.6.8%,P=0.029).Multivariate analysis identifi ed hemoglobin level and sex as independent predictors of the PRU value(y=456.355−1.736 x 1−31.880 x 2,P<0.05).On receiver operating characteristic curve analysis,PRU values could signifi cantly discriminate between patients with and patients without cardiac death,unstable angina,and rehospitalization for target lesion revascularization(area under the curve 0.758,95%confi dence interval 0.62–0.85,P=0.001,P<0.05).Conclusion:In patients with ACS,HPPR to a 600 mg loading dose of clopidogrel is associated with worse outcomes after PCI.There is some relationship between the PRU value and the hemoglobin level and sex.PRU values can predict the prognosis.展开更多
The paper describes the instrumentation for studying temperature and void reactivity effects that were developed at VR-I zero power reactor. Further are described its operational parameters, fields and ways of its uti...The paper describes the instrumentation for studying temperature and void reactivity effects that were developed at VR-I zero power reactor. Further are described its operational parameters, fields and ways of its utilization as well as issues connected to its implementation into the reactor core.展开更多
Antiplatelet therapy with aspirin or clopidogrel or both is the standard care for patients with proven coronary or peripheral arterial disease,especially those undergoing endovascular revascularization procedures. How...Antiplatelet therapy with aspirin or clopidogrel or both is the standard care for patients with proven coronary or peripheral arterial disease,especially those undergoing endovascular revascularization procedures. However,despite the administration of the antiplatelet regiments,some patients still experience recurrent cardiovascular ischemic events. So far,it is well documented by several studies that in vitro response of platelets may be extremely variable. Poor antiplatelet effect of clopidogrel or high on-treatment platelet reactivity(HTPR) is under investigation by numerous recent studies. This review article focuses on methods used for the ex vivo evaluation of HTPR,as well as on the possible underlying mechanisms and the clinical consequences of this entity. Alternative therapeutic options and future directions are also addressed.展开更多
Ambient volatile organic compounds （VOCs） were sampled at six sites in Beijing in the summer of 2004 and analyzed by GCMS. The chemical reactivities of 73 quantified VOCs species were evaluated by OH loss rates （LO...Ambient volatile organic compounds （VOCs） were sampled at six sites in Beijing in the summer of 2004 and analyzed by GCMS. The chemical reactivities of 73 quantified VOCs species were evaluated by OH loss rates （LOH） and ozone formation potentials （OFPs）. Top 15 reactive species, mainly alkenes and aromatics, were identified by these two methods, and accounted for more than 70% of total reactivity of VOCs. In urban areas, isoprene was the most reactive species in term of OH loss rate, contributing 11.4% to the LOH of VOCs. While toluene, accounting for 9.4% of OFPs, appeared to have a long-time role in the photochemical processes. Tongzhou site is obviously influenced by local chemical industry, but the other five sites showed typical urban features influenced mainly by vehicular emissions.展开更多
The purpose of this study is to investigate the catalytic effects of alkali and alkaline earth metallic species （AAEM） on char conversion during the gasification in steam and the changes in ex-situ char reactivity i...The purpose of this study is to investigate the catalytic effects of alkali and alkaline earth metallic species （AAEM） on char conversion during the gasification in steam and the changes in ex-situ char reactivity in oxygen after the gasification in steam using different forms （i.e. H-form, Na-form） of Shengli brown coal. The surface area, AAEM concentration and carbon crystallite of chars were obtained to understand the change in char reactivity. It was found that not only Na concentration and carbon structure were the main factors governing the char reactivity in the atmosphere of steam and oxygen, but also they interacted each other. The presence of Na could facilitate the formation of disordering carbon structure in char, and the amorphous carbon structure would in turn affect the distribution of Na and thus its catalytic performance. The surface area and pore volume had very little relationship with the char＇s reactivity. Addi- tionally, the morphology of chars from different forms of coals were observed using scanning electron microscope （SEM）.展开更多
A series of trans-1,4-butadiene/isoprene copolymers were prepared using the catalyst system TiCl4/MgCl2-Al（i- Bu）3 with bulk precipitation technology at different temperatures. Monomers reactivity ratios were calcul...A series of trans-1,4-butadiene/isoprene copolymers were prepared using the catalyst system TiCl4/MgCl2-Al（i- Bu）3 with bulk precipitation technology at different temperatures. Monomers reactivity ratios were calculated based on the Kelen-Tiid6s （K-T） method and the Mao-Huglin （M-H） method. The influence of temperature on copolymer composition and polymerization rate was discussed in detail. The increase of reaction temperature brought the decrease of butadiene reactivity ratio rBd and supplied an effective adjustment on copolymers＇ composition distribution.展开更多
Petroleum coke was thermally treated on a fixed bed reactor in a temperature range of 1173-1673 K. The changes of the elemental composition and crystalline structure of petroleum coke, with heat treatments as well as ...Petroleum coke was thermally treated on a fixed bed reactor in a temperature range of 1173-1673 K. The changes of the elemental composition and crystalline structure of petroleum coke, with heat treatments as well as the gasification reactivity of the heat-treated petroleum cokes were investigated. The results showed that the petroleum coke was carbonized and grapbitized to a higher degree with increasing heating temperature, while the gasification reactivity decreased. The treatment at temperatures of 1173 and 1473 K significantly enlarged the specific surface area and the pore volume of petroleum coke. Both the specific surface area and the pore volume decreased at 1673 K. An empirical normal distribution function model （NDFM） was found to fit the gasification rates of petroleum coke well. The correlation coefficient of petroleum coke by normal distribution function model at different heat treatment temperatures is between 0.93 and 0.95.展开更多
IM To evaluate the relationship between nitric oxide (NO) and hyperdynamic circulatory status in portal hypertension.METHODS Twenty male SpragueDawley rats (weighing 200g±20g) randomized into two groups, portal...IM To evaluate the relationship between nitric oxide (NO) and hyperdynamic circulatory status in portal hypertension.METHODS Twenty male SpragueDawley rats (weighing 200g±20g) randomized into two groups, portal hypertension group (n=12) and the controls (n=8). Portal hypertensive models were established by means of graded constriction of the portal vein. The concentrations of nitrite (NO2) in portal vein and peripheral blood were measured to reflect NO levels with flourimetric analysis. The reactivitiy of isolated abdominal aortic rings from partial portal veinconstricted and shamoperated rats was observed by potassium chloride (KCl) (10mmol/L-80mmol/L) and phenylephrine (10-9mol/L10-4mol/L) with or without NO synthase inhibitor NωnitroLarginine (LNNA).RESULTS Serum concentrations of NO2 in portal vein (0766μmol/L±0097μmol/L) and peripheral blood (0687μmol/L±0092μmol/L) were elevated in portal hypertensive rats as compared with those in controls (0613μmol/L±0084μmol/L, 0591μmol/L±0045μmol/L, P<001, respectively). The rates of NO2 in portal vein blood were markedly higher than those in peripheral blood (P<005) of portal hypertensive rats. Abdominal aortic rings from portal veinconstricted rats exhibited significantly impaired contractility to phenylephrine and potassium chloride as compared with the controls. The EC50 values of KCl were markedly higher in portal hypertensive rings (265mmol/L±09mmol/L) than those of the control rings (223mmol/L±17mmol/L, P<001), and so were the EC50 values of phenylephrine (372nmol/L±04nmol/L) vs (281nmol/L±02nmol/L, P<001). After preincubation of rings with LNNA, the difference in EC50 values no longer statistically significant between portal hypertensive and control rings in both KCl (2018mmol/L±08mmol/L, and 194mmol/L±12mmol/L, P>005) and phenylephrine (224nmol/L±18nmol/L, 218nmol/L±14nmol/L, P>005). However, the maximal KCl and phenylephrineinduced contractions were still lower in portal hypertensive rings (KCl: 108g±01g, phenylephrine: 143g±014g) than those of the control rings (KCl: 121g±011g, phenylephrine: 172g±011g, P<005, respectively). This showed that addition of the NO synthase inhibitor LNNA could partially restore contractile responses to KCl and phenylephrine in portal hypertensive rings.CONCLUSION NO overproduction inhibits the vascular reactivity to vasocontrictors, and it might be one of the main causes which results in vasodilatation and hyperdynamic circulatory status in portal hypertension.展开更多
More detailed analysis of a mutual relationship of impact sensitivity(detected by sound) and crystal lattice free volume, △V, for the 18 nitramines shows that its course is not unequivocal. For a part of the studied ...More detailed analysis of a mutual relationship of impact sensitivity(detected by sound) and crystal lattice free volume, △V, for the 18 nitramines shows that its course is not unequivocal. For a part of the studied compounds this sensitivity has increased with increase of the AV values, but for fairly big number of nitramines the relationship works in the opposite direction, especially for data of 1,3,5-trinitro-1,3,5-triazinane, 1,3,5,7-tetranitro-1,3,5,7-tetrazocane. and β-and ε-polymorphs of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane. Initiation reactivity of technical ε-polymorph of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane gives the impression by disorderliness in distribution of the actions of forces in its crystal lattice in comparison with its RS(reduced sensitivity) or chemically pure analogue. Limitations of partial shapes of the mentioned relationship by the molecular-structural similarity, and already published information about the decisive factors governing the crystal structure, signalizes a higher influence of the intermolecular interactions in a crystal lattice in comparison with influence of the crystal lattice free volume for initiation of the crystalline EMs.展开更多
The relationship between friction sensitivity(FS) and the crystal lattice free space per molecule, △V. of thirteen nitramines is described by a linear equation, divided into a number of the partial relationships with...The relationship between friction sensitivity(FS) and the crystal lattice free space per molecule, △V. of thirteen nitramines is described by a linear equation, divided into a number of the partial relationships with strong limitations by their molecular structure characteristics. Increasing FS due to raising of the △V values is not clearly confirmed. The influence of the △V values on friction sensitivity of nitramines is similar to that of their aza atoms which influence the mutual orientations of nitro groups in neighboring molecules. The dipole-dipole interaction of the oxygen and nitrogen atoms of nitro groups in neighboring nitramine molecules has a major effect on their own FS. In accordance with this interaction, a directly proportional relationship was derived between FS and the intrinsic gas phase molecular volume, V_(int), of the nitramines mentioned, which is divided also into several straight lines according to relatively tight molecular structure similarity. The relationships found again confirm a level of disorder in the distribution of the forces in the crystal lattice of the "common" quality of ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, in comparison with its reduced sensitivity(RS) or chemically pure analogue.展开更多
基金Supported by National Natural Science Foundation of China(50976032,51776070)。
文摘Oxygen carriers play a fundamental role in chemical looping combustion(CLC).Iron-based carriers have been extensively investigated owing to their abundance and environmentally friendly.However,the reactivity and separability of iron-based carriers require further enhancement.This study investigates the effect of the concentration of Mn doping on reactivity,elastic properties and magnetic properties based on density functional theory(DFT)calculations.Theoretical results demonstrate that Mn doping effectively enhances reactivity by reducing the oxygen vacancy formation energy(E_(vac))from 2.33 to 0.87 eV.However,Mn doping introduces HV/EV Ms lattice distortions that deteriorate elastic properties,thereby reducing wear resistance,as evidenced by a 54.54%decrease in the hardness-to-Young's modulus ratio(H_(v)/E_(v))forα-Fe_(2)O_(3)and an 83.33%reduction for Fe_(3)O_(4).Furthermore,Mn doping also modifies magnetic properties.The maximum of saturation magnetization(M_(s))of Fe_(3)O_(4)reaches 121.02 emu/g at 33.33%Mn doping concentration.Finally,systematic evaluation identifies 33.33%as the optimal Mn doping concentration,achieving a balance in enhanced reactivity,superior magnetic performance,and retained elastic stability.
文摘Knowing the precise relationship between fuel loading and reactivity is essential for guiding reactor criticality extrapolation and online refueling in molten salt reactors(MSRs).This study aims to explore and explain the linear relationship between reactivity and the reciprocal of uranium concentration in thermal-spectrum MSRs.By applying neutron balance theory,we analyzed the neutron absorption cross sections of various nuclides in single-lattice models with varying fuel concentrations.Our findings reveal a simple linear correlation between reactivity and the reciprocal of uranium concentration,which can be explained from the perspective of nuclear reaction cross sections that adhere to the 1/v law in the thermal neutron spectrum.Furthermore,we identified that the neutron absorption single-group cross sections of structural materials and carrier salts exhibit an approximately linear relationship with the fission single-group cross section of ^(235) U;similarly,the reciprocal of ^(235)U’s fission cross section exhibits an approximately linear relationship with uranium concentration.This linear relationship deviates as the volume fraction of molten salt increases,due to a greater proportion of neutrons being captured in the resonance energy spectrum.However,it remains valid for molten salt volume fractions up to 25%and demonstrates broad applicability in the physical design and operation of thermal molten salt reactors.
基金supports from the National Natural Science Foundation of China(No.52174272)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2021zzts0306)the Hunan Provincial Natural Science Foundation of China(No.2020JJ5736).
文摘Tetrasodium iminodisuccinate(IDS)was used as an inhibitor in the separation of sphalerite and pyrite in the EX−Cu(II)(ethyl xanthate and Cu2+)system.The flotation test results demonstrated that IDS can effectively separate sphalerite and pyrite under low alkaline conditions.Furthermore,high-quality zinc concentrates with a Zn grade of 58.48%and a recovery of 91.24%through mixed mineral flotation were obtained.The fundamental mechanisms were investigated through surface wettability tests,adsorption capacity tests,LEIS,FTIR,and XPS.The results confirmed that IDS prevents the adsorption of EX on the surface of pyrite,thereby reducing the response and reactivity of pyrite.The introduction of IDS causes the detachment of Cu2+from the Cu-activated pyrite surface.This process allowed IDS to chelate with the Fe sites on the surface of pyrite through the-COO-and N-centered active groups.By contrast,IDS exhibits weaker adhesion on the surface of Cu-activated sphalerite,making it easily displaced by EX through competitive adsorption.
文摘The pressure and temperature increase resulting from the impact of different threats onto target materials is analyzed with a unified laboratory-scale setup.This allows deriving qualitative information on the occurring phenomenology as well as quantitative statements about the relative effects sizes as a function of target material and threat.The considered target materials are steel,aluminum,and magnesium.As threats,kinetic energy penetrator,explosively formed projectile,and shaped charge jet are used.For the investigated combinations,the measured overpressures vary by a factor of up to 5 for a variation of the material,by a factor of up to 7 for a variation of the threat,and by a factor larger than 15for a simultaneous variation of both.The obtained results as well as the experimental approach are relevant for the basic understanding of impact effects and risks due to material reactivity.The paper combines two main aims.Firstly,to provide a summary of own prior work in a coherent journal article and,secondly,to review and discuss these earlier results with a new perspective.
基金supported by JST Grant Number JPMJPF2104,Japan.Az Zahra and Alahakoon gratefully acknowledge MEXT of Japan for the scholarship.
文摘The thermal conversion process known as biomass gasification has the potential to produce environmentally friendly fuels such as hydrogen.However,tar generation during the gasification remains an issue,affecting operational efficiency and environmental health.Biochar has been confirmed as an inexpensive and efficient catalyst for tar removal.The challenge lies in creating a highly reactive biochar which can be applied for different types of biomass with varying properties.This review discusses the factors that affect biochar’s reactivity as a catalyst for tar reforming.Additionally,incorporating biochar into a gasification scenario with raw biomass offers a practical solution by leveraging the synergistic behavior.However,this synergy could be either positive or negative:the positive synergy enhances tar removal while the negative synergy has the opposite effect.The numerous factors affecting the results of gasification are presented in this review.It is concluded that the positive synergistic effect resulted from the balance between the available reactants from biomass and biochar,the optimal gas flowrate and the active sites on the carbon surface.Understanding these interactions is crucial for optimizing biochar performance for tar removal.Ultimately,this research provides insights into biochar’s role in biomass gasification and suggests improvements for future studies to enhance the feasibility of biomass gasification with the assistance of biochar.
基金supported by the National Natural Science Foundation of China(Grant Nos.T2222027 and 12202416)。
文摘Aluminum(Al)powder is widely applied in thermobaric explosives due to its high energy density and favorable reaction kinetics.However,the inert oxide layer(Al_(2)O_(3))on Al particles limits combustion reactivity and energy efficiency.Fluoride-based surface modification has been developed as an effective approach to address this issue.Here,four classical fluoropolymers(F11,F14,PVDF,PTFE)are employed as coatings to prepare core-shell Al/Fluoropolymer.The combustion experimental results demonstrate that the core-shell Al/PTFE exhibits the highest flame propagation rate(52.88 mm·ms^(-1))and pressure output(109.02 k Pa)performance.Consequently,core-shell Al/PTFE is selected as a high-energy fuel to prepare RDX/Al/PTFE microspheres via the emulsion and solvent evaporation method,which can enhance the energy performance of RDX.The effects of the core-shell Al/PTFE ratio and RDX content on the combustion heat and pressure output are systematically investigated.The peak pressure reaches a maximum of 187.8 k Pa when the mass ratio of RDX,Al,and PTFE is 60:25:10.Additionally,RDX/Al/PTFE microspheres exhibit significantly higher laser-induced air shock velocities,detonation heat,and detonation pressure than those of pure RDX and RDX/Al.The mechanism underlying the enhanced reactivity and energetic performance is attributed to the ability of PTFE to etch the inert Al_(2)O_(3)shell on the surface of Al particles,thereby improving post-combustion reactions and significantly increasing the overall energy output of RDX explosives.This work offers a novel design strategy for high-energy structural thermobaric explosives for the practical applications.
基金Project (50864001) supported by the National Natural Science Foundation of China
文摘The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by frontier orbital methods.The cell volume expands due to the presence of impurity.Co and Ni mainly affect the bands near Fermi levels,while As mainly affects the shallow and deep valence bands,and Se and Te mainly affect the deep valence bands.Electronic density analysis suggests that there exists a strong covalent interaction between hetero atom and its surrounding atoms.By frontier orbital calculation,it is suggested that As,Co and Ni have greater influence on the HOMO and LUMO of pyrite than Se and Te.In addition,pyrite containing As,Co or Ni is easier to oxidize by oxygen than pyrite containing Se or Te,and pyrite containing Co or Ni has greater interaction with collector.These are in agreement with the observed pyrite practice.
基金Project(51374253)supported by the National Natural Science Foundation of China
文摘Effect of sulfur impurity on coke reactivity was investigated by simulating petroleum coke with low-impurity pitch coke and impurities doping. And its mechanism was discussed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that sulfur has strong catalysis on both air and CO2 reactivity of coke in the case of no other impurity interference. Its catalysis is probably realized by triggering organic sulfur→H2S→SO2→COS and elemental sulfur (Sx)→SO2 and organic sulfur→H2S→COS→Sx→C2S→COS reaction systems during coke?O2 and coke?CO2 reactions, respectively, which are partly circular with functions of increasing carbon consumption and enlarging coke specific surface area.
基金supported by the National Natural Science Foundation of China (21573232, 21576251, 21676269)National Key Projects for Funda-mental Research and Development of China (2016YFA0202801)Department of Science and Technology of Liaoning province under contract of 2015020086–101~~
文摘The formations and transformations of the chemical bonds of reactants and intermediates on cata- lyst surfaces occur in conjunction with the evolution of heat during catalytic reactions. Measure- ment of this evolved heat is helpful in terms of understanding the nature of the interactions be- tween the catalyst and the adsorbed species, and provides insights into the reactivity of the catalyst. Although various techniques have previously been applied to assessments of evolved heat, direct measurements using a Tian-Calvet microcalorimeter are currently the most reliable method for this purpose. In this review, we summarize the relationship between the adsorption/reaction energetics determined by microcalorimetry and the reactivities of supported catalysts, and examine the im- portant role of microcalorimetry in understanding catalytic performance from the energetic point of view.
基金Beijing Higher Education Young Elite Teacher Project(Grant No.YETP0064)from Beijing Municipal Education Commission
文摘Various platelet function tests are currently used to identify responsiveness to antiplatelet therapy. 176 ACS patients were enrolled and Linear regression and Kappa consistency analysis showed there was a significant but moderate correlation between platelet inhibition rate and a significant but fair agreement between high clopidogrel on-treatment platelet reactivity tested by light transmission aggregometry and thrombelastography.
基金the Science Fund for Distinguished Young Scholars from the Fourth Affi liated Hospital of Harbin Medical University(no.HYDSYJQ201504)The funders had no role in the study design,data collection and analysis,decision to publish,or preparation of the manuscriptThe clinical trial is registered as ChiCTR-IOR-17013665。
文摘Objectives:We sought to determine whether high posttreatment platelet reactivity(HPPR)to a 600 mg loading dose of clopidogrel affects outcomes in Chinese patients with acute coronary syndrome(ACS)following percutaneous coronary intervention(PCI)and to investigate whether there is a relationship between the number of platelet reactivity units(PRUs)and the characteristics of the patients.Background:Although impaired platelet response to clopidogrel is a strong predictor of unfavorable outcome after PCI,the impact of HPPR to a 600 mg loading dose of clopidogrel in Chinese patients with ACS undergoing PCI is still unknown.Methods:We performed observational research on 134 unselected patients with ACS undergoing urgent or planned PCI with a 600 mg loading dose of clopidogrel.Platelet activation was expressed as the PRU value measured by the VerifyNow assay.Results:Among the 134 patients(mean age 60.62 years[standard deviation 9.13 years],60.4%male),there were 46 patients with HPPR(34.3%)and 88 patients without HPPR(65.7%).At a mean follow-up of 6 months(standard deviation 1 month),the rates of cardiac death,unstable angina,and rehospitalization for target lesion revascularization were higher in the HPPR group(19.6%vs.6.8%,P=0.029).Multivariate analysis identifi ed hemoglobin level and sex as independent predictors of the PRU value(y=456.355−1.736 x 1−31.880 x 2,P<0.05).On receiver operating characteristic curve analysis,PRU values could signifi cantly discriminate between patients with and patients without cardiac death,unstable angina,and rehospitalization for target lesion revascularization(area under the curve 0.758,95%confi dence interval 0.62–0.85,P=0.001,P<0.05).Conclusion:In patients with ACS,HPPR to a 600 mg loading dose of clopidogrel is associated with worse outcomes after PCI.There is some relationship between the PRU value and the hemoglobin level and sex.PRU values can predict the prognosis.
文摘The paper describes the instrumentation for studying temperature and void reactivity effects that were developed at VR-I zero power reactor. Further are described its operational parameters, fields and ways of its utilization as well as issues connected to its implementation into the reactor core.
文摘Antiplatelet therapy with aspirin or clopidogrel or both is the standard care for patients with proven coronary or peripheral arterial disease,especially those undergoing endovascular revascularization procedures. However,despite the administration of the antiplatelet regiments,some patients still experience recurrent cardiovascular ischemic events. So far,it is well documented by several studies that in vitro response of platelets may be extremely variable. Poor antiplatelet effect of clopidogrel or high on-treatment platelet reactivity(HTPR) is under investigation by numerous recent studies. This review article focuses on methods used for the ex vivo evaluation of HTPR,as well as on the possible underlying mechanisms and the clinical consequences of this entity. Alternative therapeutic options and future directions are also addressed.
基金National Natural Science Foundation of China(No.40575059 and No.20637001).
文摘Ambient volatile organic compounds （VOCs） were sampled at six sites in Beijing in the summer of 2004 and analyzed by GCMS. The chemical reactivities of 73 quantified VOCs species were evaluated by OH loss rates （LOH） and ozone formation potentials （OFPs）. Top 15 reactive species, mainly alkenes and aromatics, were identified by these two methods, and accounted for more than 70% of total reactivity of VOCs. In urban areas, isoprene was the most reactive species in term of OH loss rate, contributing 11.4% to the LOH of VOCs. While toluene, accounting for 9.4% of OFPs, appeared to have a long-time role in the photochemical processes. Tongzhou site is obviously influenced by local chemical industry, but the other five sites showed typical urban features influenced mainly by vehicular emissions.
文摘The purpose of this study is to investigate the catalytic effects of alkali and alkaline earth metallic species （AAEM） on char conversion during the gasification in steam and the changes in ex-situ char reactivity in oxygen after the gasification in steam using different forms （i.e. H-form, Na-form） of Shengli brown coal. The surface area, AAEM concentration and carbon crystallite of chars were obtained to understand the change in char reactivity. It was found that not only Na concentration and carbon structure were the main factors governing the char reactivity in the atmosphere of steam and oxygen, but also they interacted each other. The presence of Na could facilitate the formation of disordering carbon structure in char, and the amorphous carbon structure would in turn affect the distribution of Na and thus its catalytic performance. The surface area and pore volume had very little relationship with the char＇s reactivity. Addi- tionally, the morphology of chars from different forms of coals were observed using scanning electron microscope （SEM）.
基金financially supported by the National Key Technology R&D Program of China(No.2011BAE26B05)the Shandong Province Natural Science Fund for Distinguished Young Scholars(No.JQ201213)+2 种基金National Natural Science Foundation of China(No.21174074)Shandong Province Science and Technology Development Plan(No.2012GGA05042)the Major Projects of Independent Innovation Achievements Transformation in Shandong Province(No.2013ZHZX1A0207)
文摘A series of trans-1,4-butadiene/isoprene copolymers were prepared using the catalyst system TiCl4/MgCl2-Al（i- Bu）3 with bulk precipitation technology at different temperatures. Monomers reactivity ratios were calculated based on the Kelen-Tiid6s （K-T） method and the Mao-Huglin （M-H） method. The influence of temperature on copolymer composition and polymerization rate was discussed in detail. The increase of reaction temperature brought the decrease of butadiene reactivity ratio rBd and supplied an effective adjustment on copolymers＇ composition distribution.
文摘Petroleum coke was thermally treated on a fixed bed reactor in a temperature range of 1173-1673 K. The changes of the elemental composition and crystalline structure of petroleum coke, with heat treatments as well as the gasification reactivity of the heat-treated petroleum cokes were investigated. The results showed that the petroleum coke was carbonized and grapbitized to a higher degree with increasing heating temperature, while the gasification reactivity decreased. The treatment at temperatures of 1173 and 1473 K significantly enlarged the specific surface area and the pore volume of petroleum coke. Both the specific surface area and the pore volume decreased at 1673 K. An empirical normal distribution function model （NDFM） was found to fit the gasification rates of petroleum coke well. The correlation coefficient of petroleum coke by normal distribution function model at different heat treatment temperatures is between 0.93 and 0.95.
文摘IM To evaluate the relationship between nitric oxide (NO) and hyperdynamic circulatory status in portal hypertension.METHODS Twenty male SpragueDawley rats (weighing 200g±20g) randomized into two groups, portal hypertension group (n=12) and the controls (n=8). Portal hypertensive models were established by means of graded constriction of the portal vein. The concentrations of nitrite (NO2) in portal vein and peripheral blood were measured to reflect NO levels with flourimetric analysis. The reactivitiy of isolated abdominal aortic rings from partial portal veinconstricted and shamoperated rats was observed by potassium chloride (KCl) (10mmol/L-80mmol/L) and phenylephrine (10-9mol/L10-4mol/L) with or without NO synthase inhibitor NωnitroLarginine (LNNA).RESULTS Serum concentrations of NO2 in portal vein (0766μmol/L±0097μmol/L) and peripheral blood (0687μmol/L±0092μmol/L) were elevated in portal hypertensive rats as compared with those in controls (0613μmol/L±0084μmol/L, 0591μmol/L±0045μmol/L, P<001, respectively). The rates of NO2 in portal vein blood were markedly higher than those in peripheral blood (P<005) of portal hypertensive rats. Abdominal aortic rings from portal veinconstricted rats exhibited significantly impaired contractility to phenylephrine and potassium chloride as compared with the controls. The EC50 values of KCl were markedly higher in portal hypertensive rings (265mmol/L±09mmol/L) than those of the control rings (223mmol/L±17mmol/L, P<001), and so were the EC50 values of phenylephrine (372nmol/L±04nmol/L) vs (281nmol/L±02nmol/L, P<001). After preincubation of rings with LNNA, the difference in EC50 values no longer statistically significant between portal hypertensive and control rings in both KCl (2018mmol/L±08mmol/L, and 194mmol/L±12mmol/L, P>005) and phenylephrine (224nmol/L±18nmol/L, 218nmol/L±14nmol/L, P>005). However, the maximal KCl and phenylephrineinduced contractions were still lower in portal hypertensive rings (KCl: 108g±01g, phenylephrine: 143g±014g) than those of the control rings (KCl: 121g±011g, phenylephrine: 172g±011g, P<005, respectively). This showed that addition of the NO synthase inhibitor LNNA could partially restore contractile responses to KCl and phenylephrine in portal hypertensive rings.CONCLUSION NO overproduction inhibits the vascular reactivity to vasocontrictors, and it might be one of the main causes which results in vasodilatation and hyperdynamic circulatory status in portal hypertension.
基金financial support from the Students Grant Projects No. SGSFCHT_2016002 of the Faculty of Chemical Technology at the University of Pardubicefinancial support The State Administration of Foreign Experts Affairs, Peoples Republic of China
文摘More detailed analysis of a mutual relationship of impact sensitivity(detected by sound) and crystal lattice free volume, △V, for the 18 nitramines shows that its course is not unequivocal. For a part of the studied compounds this sensitivity has increased with increase of the AV values, but for fairly big number of nitramines the relationship works in the opposite direction, especially for data of 1,3,5-trinitro-1,3,5-triazinane, 1,3,5,7-tetranitro-1,3,5,7-tetrazocane. and β-and ε-polymorphs of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane. Initiation reactivity of technical ε-polymorph of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane gives the impression by disorderliness in distribution of the actions of forces in its crystal lattice in comparison with its RS(reduced sensitivity) or chemically pure analogue. Limitations of partial shapes of the mentioned relationship by the molecular-structural similarity, and already published information about the decisive factors governing the crystal structure, signalizes a higher influence of the intermolecular interactions in a crystal lattice in comparison with influence of the crystal lattice free volume for initiation of the crystalline EMs.
基金financial support from the Students Grant Projects No. SGSFCHT_2016002 of the Faculty of Chemical Technology at the University of Pardubicefinancial support of the Chinese State Administration of Foreign Experts Affairs
文摘The relationship between friction sensitivity(FS) and the crystal lattice free space per molecule, △V. of thirteen nitramines is described by a linear equation, divided into a number of the partial relationships with strong limitations by their molecular structure characteristics. Increasing FS due to raising of the △V values is not clearly confirmed. The influence of the △V values on friction sensitivity of nitramines is similar to that of their aza atoms which influence the mutual orientations of nitro groups in neighboring molecules. The dipole-dipole interaction of the oxygen and nitrogen atoms of nitro groups in neighboring nitramine molecules has a major effect on their own FS. In accordance with this interaction, a directly proportional relationship was derived between FS and the intrinsic gas phase molecular volume, V_(int), of the nitramines mentioned, which is divided also into several straight lines according to relatively tight molecular structure similarity. The relationships found again confirm a level of disorder in the distribution of the forces in the crystal lattice of the "common" quality of ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, in comparison with its reduced sensitivity(RS) or chemically pure analogue.
