The reaction kinetics of roasting zinc silicate using NaOH was investigated.The orthogonal test was employed to optimize the reaction conditions and the optimized reaction conditions were as follows:molar ratio of NaO...The reaction kinetics of roasting zinc silicate using NaOH was investigated.The orthogonal test was employed to optimize the reaction conditions and the optimized reaction conditions were as follows:molar ratio of NaOH to Zn2SiO4 of 16:1,reaction temperature of 550°C,and reaction time of 2.5 h.In order to ascertain the phases transformation and reaction processes of zinc oxide and silica,the XRD phase analysis was used to analyze the phases of these specimens roasted at different temperatures.The final phases of the specimen roasted at 600°C were Na2ZnO2,Na4SiO4,Na2ZnSiO4 and NaOH.The reaction kinetic equation of roasting was determined by the shrinking unreacted core model.Aiming to investigate the reaction mechanism,two control models of reaction rate were applied:chemical reaction at the particle surface and diffusion through the product layer.The results indicated that the diffusion through the product layer model described the reaction process well.The apparent activation energy of the roasting was 19.77 kJ/mol.展开更多
Necessary and sufficient conditions for azeotropy in reactive mixtures are derived in terms of elemental composition, which shows that in the space of elemental compositions, they take the same functional form as the ...Necessary and sufficient conditions for azeotropy in reactive mixtures are derived in terms of elemental composition, which shows that in the space of elemental compositions, they take the same functional form as the conditions for azeotropy in non-reactive mixtures. The production of methyl tert-butyl ether (MTBE) is taken as an example. It is found that there are a 'pseudo' intermediate-boiling ternary reactive azeotrope at p = 101.325kPa and two 'real' ternary reactive azeotropes at p = 101.325 Pa. The introduced elemental compositions also reduce the dimensionality of the phase diagrams and provide a natural set of variables for visualization of phase behavior.展开更多
An efficient analytical method combining pyrolysis and capillary GC/MS has been developed for determination and quantitation of targeted polycyclic aromatic hydrocarbons.The limit of detection ranged from 0.29 μg/g t...An efficient analytical method combining pyrolysis and capillary GC/MS has been developed for determination and quantitation of targeted polycyclic aromatic hydrocarbons.The limit of detection ranged from 0.29 μg/g to 43.46 μg/g,and repeatability values were between 0.1% and 8.2% for blank spiked samples and between 0.1 % and 9.8% for real samples of heavy oils.Through application of the proposed method in hydrotreating processes,it has been found out that heavy oils before and after the specified hydroprocessing treatment exhibited a diverse PAHs distribution which might be determined by the discrepancy in their intrinsic contents and hydrogenation reactivity.Furthermore,the hydrogenation reactivity of different polycyclic aromatic hydrocarbons was further investigated and discovered to be more interrelated to molecular structure and rings alignment or conjugation mode.展开更多
The influence of mischmetal addition on physicochcmical properties of PtSnNa/ZSM-5 catalyst was studied by means of XRF, H2 chemisorption, XRD, TPR, NH3-TPD and TPO techniques. The results showed that the presence of ...The influence of mischmetal addition on physicochcmical properties of PtSnNa/ZSM-5 catalyst was studied by means of XRF, H2 chemisorption, XRD, TPR, NH3-TPD and TPO techniques. The results showed that the presence of mischmetal had an obvious impact on the catalytic performance of the PtSnNa/ZSM-5 catalyst. A suitable content of mischmetal not only could enhance the interactions between Pt species and the support, but also inhibit the formation of coke during the reaction, thus improving the catalytic activity and stability. In our experiments, when the content of mischmetal was 3m%, the catalyst exhibited best catalytic performance. However, the continuous addition of mischmetal could promote the reduction of Sn species to metallic tin, which was disadvantageous to the reaction.展开更多
The conversion rules under which an algebraic expression can be obtained from a corresponding photoionizationGoldstone diagram have been given systematically in the present work.The electronic correlations in thephoto...The conversion rules under which an algebraic expression can be obtained from a corresponding photoionizationGoldstone diagram have been given systematically in the present work.The electronic correlations in thephotoionization processes then could be studied diagrammatically.The application to atomic scandium shows that thepresent theoretical scheme can give reasonable photoionization cross sections,which agree well with the experimentalresults.展开更多
Nowadays, in order to satisfy the ISO 9001: 2015 requirements, organizations access to information from web sites, consultant guides, Internet forums, books, and courses, as a first approximation, however, the qualit...Nowadays, in order to satisfy the ISO 9001: 2015 requirements, organizations access to information from web sites, consultant guides, Internet forums, books, and courses, as a first approximation, however, the quality, reliability, validity, and accuracy of the information content in these is limited. The research topic of this study is the use of theoretical methodological tools, whose implementation supports the organizations in the fulfillment of requirement 4 of ISO 9001:2015, adapting it to their particular needs, minimizing rework in the documentation, increasing the motivation of the personnel involved and promoting well-being within the work environment. Some theoretical methodological tools were implemented in the case of Engineering laboratories of the Faculty of Higher Studies Arag6n, that support and complement the teaching-learning process in the theoretical-practical subjects of the curricula of the engineering bachelor's degrees, providing students with practical training in the use of equipment, devices, and tools, as well as extracurricular courses. In the study participated the stakeholders of laboratories. From the results, it was observed that the time for the documentation of the quality management system was reduced using the theoretical tools proposed in this study. In conclusion, this study will thus be useful as a starting point in using formal tools for the implementation of ISO 9001: 2015 standard.展开更多
In the present work,the mechanical properties of bulk nanocrystalline(NC) bcc Fe under tensile deformation have been studied by molecular dynamics(MD) simulations.Average flow stress was found to decrease with grain r...In the present work,the mechanical properties of bulk nanocrystalline(NC) bcc Fe under tensile deformation have been studied by molecular dynamics(MD) simulations.Average flow stress was found to decrease with grain refinement below 13.54 nm,indicating a breakdown in the Hall-Petch relation.A change from grain boundary(GB) mediated dislocation activities to GB activities may be a possible explanation of the breakdown in the Hall-Petch relation.The results also indicate that the average flow stress increases with increasing strain rates and decreasing temperatures.Stress induced phase transformations were observed during the tensile deformation of NC Fe,and such phase transformations were found to be reversible with respect to the applied stress.The maximum fraction of the cp atoms was also found to increase with increasing applied stress.Significant phase transformation occurred in the stacking fault zone due to dislocation activities for large grain size(13.54 nm),while significant phase transformation occurred in the GBs due to GB activities for small grain size(3.39 nm).At deformation temperature of 900 K and above,no apparent phase transformation occurred because all atoms at GBs and grain interior could easily rearrange their position by thermal activation to form local vacancies/disordered structures rather than ordered close packed(cp) structures.展开更多
Most E26 transformation-specific (ETS) transcription factors are involved in the pathogenesis and progression of cancer. This is in part due to the roles of ETS transcription factors in basic biological processes su...Most E26 transformation-specific (ETS) transcription factors are involved in the pathogenesis and progression of cancer. This is in part due to the roles of ETS transcription factors in basic biological processes such as growth, proliferation, and differentiation, and also because of their regulatory functions that have physiological relevance in tumorigenesis, immunity, and basal cellular homoeostasis. A member of the E74-1ike factor (ELF) subfamily of the ETS transcription factor family--myeloid elf-l-Uke factor (MEF), designated as ELF4~has been shown to be critically involved in immune response and signalling, osteogenesis, adipo- genesis, cancer, and stem cell quiescence. ELF4 carries out these functions as a transcriptional activator or through interactions with its partner proteins. Mutations in ELF4 cause aberrant interactions and induce downstream processes that may lead to dis- eased cells. Knowing how ELF4 impinges on certain cellular processes and how it is regulated in the cells can lead to a better understanding of the physiological and pathological consequences of modulated ELF4 activity.展开更多
In this paper,a microscopic phase-field model was used to investigate the effect of the oriented diffusion channel and the phases' effect mechanism for the Ni75Al6.0V19.0 alloy during a phase transformation proces...In this paper,a microscopic phase-field model was used to investigate the effect of the oriented diffusion channel and the phases' effect mechanism for the Ni75Al6.0V19.0 alloy during a phase transformation process.A diffusion channel of V was formed in the [100] direction.The oriented growth of DO22 in this direction,when an elastic misfit stress field existed,forced Al to form a diffusion channel next to DO22,resulting in L12-oriented growth.With an increase in stress,the oriented growth increased initially and then decreased.At a higher stress,the average values of the occupation probability for V atoms became constant later while Al atoms earlier.展开更多
In general,heat transfers can be classified into two categories according to the purposes of object heating or cooling and the heat to work conversion.Recently,a new physical quantity,entransy(or potential energy),was...In general,heat transfers can be classified into two categories according to the purposes of object heating or cooling and the heat to work conversion.Recently,a new physical quantity,entransy(or potential energy),was proposed to describe the ability of heat transfer with the former purpose.This paper addresses the concept of potential energy in terms of the heat transfer processes for the latter purpose,named the conversion potential energy.The physical meaning of this newly introduced concept is the potential energy for the heat to work conversion stored in the equivalent mass of heat(thermomass) derived on the basis of the Einstein's special theory of relativity.The dissipation of conversion potential energy occurs during the real irreversible heat to work conversion processes as a measure of the conversion irreversibility.Finally,a heat to work conversion problem of a heat exchanger group is provided to show that the minimum conversion potential energy dissipation rate can be used as an optimization criterion for the heat transfer performance with the purpose of the heat to work conversion.展开更多
A numerical model is proposed to analyze mass, momentum, and energy transfer between plasma andparticles in d.c. arc-heated and confined jet reactors at atmospheric pressure. It emphasizes the phasechange and thermal ...A numerical model is proposed to analyze mass, momentum, and energy transfer between plasma andparticles in d.c. arc-heated and confined jet reactors at atmospheric pressure. It emphasizes the phasechange and thermal chemistry of particles and includes some other effects such as flow turbulence, gascompressibility and temperature-dependence of the transport properties under the plasma condition.Example calculations for plasma-dissociated zircon process indicate the influences of reactor operationparameters on the plasma jet and particle behavior.展开更多
Urban and regional air pollutions are characterized by high concentrations of secondary pollutants such as photo-oxidants (mainly ozone) and fine particulate matter, which are formed through chemical reactions of th...Urban and regional air pollutions are characterized by high concentrations of secondary pollutants such as photo-oxidants (mainly ozone) and fine particulate matter, which are formed through chemical reactions of the primary pollutants emitted from various sources. The accumulation of these pollutants under stagnant meteorological conditions results in the formation of gray haze, reducing visibility and causing major impacts on human health and climate. In an air pollution complex, the co- existence of high concentrations of primary and secondary gaseous and particulate pollutants provides a large amount of reac- tants for heterogeneous reactions on the surface of fine particles; these reactions change the oxidizing capacity of the atmos- phere, as well as chemical compositions along with the physicochemical and optical properties of particulate matter, thereby accelerating formation of the air pollution complex and gray haze. Using in situ technologies, such as diffuse reflectance infra- red Fourier-transform spectroscopy and single-particle Raman spectroscopy, we systematically investigated the reaction kinet- ics and mechanisms of gaseous pollutants (i.e., NO2, SO2, 03, and formaldehyde) on the surfaces of the major components of atmospheric particles such as CaCO3, kaolinite, montmorillonite, NaC1, sea salt, A1203, and Tit2. We found that the main re- action products were sulfate, nitrate, or formate, which can change the hygroscopicity and light extinction parameters of those particles significantly. By analyzing the reaction kinetics of these heterogeneous reactions, we identified synergetic mechanisms of the three ternary reaction systems, ,i.e., NOE-particles-H2O, SO2-particles-O3, and organics/SO2-particles-UV illumination. These synergetic mechanisms can provide experimental and theoretical bases for understanding the feedback mechanisms and nonlinear processes in the formation of an air pollution complex and gray haze.展开更多
基金Projects(51774070,51204054)supported by the National Natural Science Foundation of ChinaProject(150204009)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(2014CB643405)supported by the National Basic Research Program of China
文摘The reaction kinetics of roasting zinc silicate using NaOH was investigated.The orthogonal test was employed to optimize the reaction conditions and the optimized reaction conditions were as follows:molar ratio of NaOH to Zn2SiO4 of 16:1,reaction temperature of 550°C,and reaction time of 2.5 h.In order to ascertain the phases transformation and reaction processes of zinc oxide and silica,the XRD phase analysis was used to analyze the phases of these specimens roasted at different temperatures.The final phases of the specimen roasted at 600°C were Na2ZnO2,Na4SiO4,Na2ZnSiO4 and NaOH.The reaction kinetic equation of roasting was determined by the shrinking unreacted core model.Aiming to investigate the reaction mechanism,two control models of reaction rate were applied:chemical reaction at the particle surface and diffusion through the product layer.The results indicated that the diffusion through the product layer model described the reaction process well.The apparent activation energy of the roasting was 19.77 kJ/mol.
基金Supported by the National Natural Science Foundation of China (No.29976035) and Zhejiang and Fujian Provincial Natural Science Foundation of China.
文摘Necessary and sufficient conditions for azeotropy in reactive mixtures are derived in terms of elemental composition, which shows that in the space of elemental compositions, they take the same functional form as the conditions for azeotropy in non-reactive mixtures. The production of methyl tert-butyl ether (MTBE) is taken as an example. It is found that there are a 'pseudo' intermediate-boiling ternary reactive azeotrope at p = 101.325kPa and two 'real' ternary reactive azeotropes at p = 101.325 Pa. The introduced elemental compositions also reduce the dimensionality of the phase diagrams and provide a natural set of variables for visualization of phase behavior.
基金support from the National Key Basic Research Science Foundation (Grant No. 2006CB202500. 4-1)
文摘An efficient analytical method combining pyrolysis and capillary GC/MS has been developed for determination and quantitation of targeted polycyclic aromatic hydrocarbons.The limit of detection ranged from 0.29 μg/g to 43.46 μg/g,and repeatability values were between 0.1% and 8.2% for blank spiked samples and between 0.1 % and 9.8% for real samples of heavy oils.Through application of the proposed method in hydrotreating processes,it has been found out that heavy oils before and after the specified hydroprocessing treatment exhibited a diverse PAHs distribution which might be determined by the discrepancy in their intrinsic contents and hydrogenation reactivity.Furthermore,the hydrogenation reactivity of different polycyclic aromatic hydrocarbons was further investigated and discovered to be more interrelated to molecular structure and rings alignment or conjugation mode.
基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (No.20100092120047)the Production and Research Prospective Joint Research Project (No.BY2009153)the National Nature Science Foundation of China (No.50873026) for financial supports
文摘The influence of mischmetal addition on physicochcmical properties of PtSnNa/ZSM-5 catalyst was studied by means of XRF, H2 chemisorption, XRD, TPR, NH3-TPD and TPO techniques. The results showed that the presence of mischmetal had an obvious impact on the catalytic performance of the PtSnNa/ZSM-5 catalyst. A suitable content of mischmetal not only could enhance the interactions between Pt species and the support, but also inhibit the formation of coke during the reaction, thus improving the catalytic activity and stability. In our experiments, when the content of mischmetal was 3m%, the catalyst exhibited best catalytic performance. However, the continuous addition of mischmetal could promote the reduction of Sn species to metallic tin, which was disadvantageous to the reaction.
基金The present study was part of The University Science & Technology Planning Program of Shandong Province under Grant No. J10LB60 (self-financing)partly supported by the Natural Science Foundation of Shandong Province under Grant No. ZR2011AM010 and 2009 Technology Innovation Fund (09L026) of Ludong University
文摘The conversion rules under which an algebraic expression can be obtained from a corresponding photoionizationGoldstone diagram have been given systematically in the present work.The electronic correlations in thephotoionization processes then could be studied diagrammatically.The application to atomic scandium shows that thepresent theoretical scheme can give reasonable photoionization cross sections,which agree well with the experimentalresults.
文摘Nowadays, in order to satisfy the ISO 9001: 2015 requirements, organizations access to information from web sites, consultant guides, Internet forums, books, and courses, as a first approximation, however, the quality, reliability, validity, and accuracy of the information content in these is limited. The research topic of this study is the use of theoretical methodological tools, whose implementation supports the organizations in the fulfillment of requirement 4 of ISO 9001:2015, adapting it to their particular needs, minimizing rework in the documentation, increasing the motivation of the personnel involved and promoting well-being within the work environment. Some theoretical methodological tools were implemented in the case of Engineering laboratories of the Faculty of Higher Studies Arag6n, that support and complement the teaching-learning process in the theoretical-practical subjects of the curricula of the engineering bachelor's degrees, providing students with practical training in the use of equipment, devices, and tools, as well as extracurricular courses. In the study participated the stakeholders of laboratories. From the results, it was observed that the time for the documentation of the quality management system was reduced using the theoretical tools proposed in this study. In conclusion, this study will thus be useful as a starting point in using formal tools for the implementation of ISO 9001: 2015 standard.
基金supported by the National Basic Research Program of China (Grant Nos. 2012CB932203 and 2012CB937500)the National Natural Science Foundation of China (Grants No. 11002151,10721202and 11072243)
文摘In the present work,the mechanical properties of bulk nanocrystalline(NC) bcc Fe under tensile deformation have been studied by molecular dynamics(MD) simulations.Average flow stress was found to decrease with grain refinement below 13.54 nm,indicating a breakdown in the Hall-Petch relation.A change from grain boundary(GB) mediated dislocation activities to GB activities may be a possible explanation of the breakdown in the Hall-Petch relation.The results also indicate that the average flow stress increases with increasing strain rates and decreasing temperatures.Stress induced phase transformations were observed during the tensile deformation of NC Fe,and such phase transformations were found to be reversible with respect to the applied stress.The maximum fraction of the cp atoms was also found to increase with increasing applied stress.Significant phase transformation occurred in the stacking fault zone due to dislocation activities for large grain size(13.54 nm),while significant phase transformation occurred in the GBs due to GB activities for small grain size(3.39 nm).At deformation temperature of 900 K and above,no apparent phase transformation occurred because all atoms at GBs and grain interior could easily rearrange their position by thermal activation to form local vacancies/disordered structures rather than ordered close packed(cp) structures.
文摘Most E26 transformation-specific (ETS) transcription factors are involved in the pathogenesis and progression of cancer. This is in part due to the roles of ETS transcription factors in basic biological processes such as growth, proliferation, and differentiation, and also because of their regulatory functions that have physiological relevance in tumorigenesis, immunity, and basal cellular homoeostasis. A member of the E74-1ike factor (ELF) subfamily of the ETS transcription factor family--myeloid elf-l-Uke factor (MEF), designated as ELF4~has been shown to be critically involved in immune response and signalling, osteogenesis, adipo- genesis, cancer, and stem cell quiescence. ELF4 carries out these functions as a transcriptional activator or through interactions with its partner proteins. Mutations in ELF4 cause aberrant interactions and induce downstream processes that may lead to dis- eased cells. Knowing how ELF4 impinges on certain cellular processes and how it is regulated in the cells can lead to a better understanding of the physiological and pathological consequences of modulated ELF4 activity.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51075335, 10902086, 50875217)the NPU Foundation for Fundamental Research (Grant No. JC201005)the Doctorate Foundation of Northwestern Polytechnical University (Grant No.CX201007)
文摘In this paper,a microscopic phase-field model was used to investigate the effect of the oriented diffusion channel and the phases' effect mechanism for the Ni75Al6.0V19.0 alloy during a phase transformation process.A diffusion channel of V was formed in the [100] direction.The oriented growth of DO22 in this direction,when an elastic misfit stress field existed,forced Al to form a diffusion channel next to DO22,resulting in L12-oriented growth.With an increase in stress,the oriented growth increased initially and then decreased.At a higher stress,the average values of the occupation probability for V atoms became constant later while Al atoms earlier.
基金supported by the NUAA Research Funding (Grant No. NS2012142)
文摘In general,heat transfers can be classified into two categories according to the purposes of object heating or cooling and the heat to work conversion.Recently,a new physical quantity,entransy(or potential energy),was proposed to describe the ability of heat transfer with the former purpose.This paper addresses the concept of potential energy in terms of the heat transfer processes for the latter purpose,named the conversion potential energy.The physical meaning of this newly introduced concept is the potential energy for the heat to work conversion stored in the equivalent mass of heat(thermomass) derived on the basis of the Einstein's special theory of relativity.The dissipation of conversion potential energy occurs during the real irreversible heat to work conversion processes as a measure of the conversion irreversibility.Finally,a heat to work conversion problem of a heat exchanger group is provided to show that the minimum conversion potential energy dissipation rate can be used as an optimization criterion for the heat transfer performance with the purpose of the heat to work conversion.
文摘A numerical model is proposed to analyze mass, momentum, and energy transfer between plasma andparticles in d.c. arc-heated and confined jet reactors at atmospheric pressure. It emphasizes the phasechange and thermal chemistry of particles and includes some other effects such as flow turbulence, gascompressibility and temperature-dependence of the transport properties under the plasma condition.Example calculations for plasma-dissociated zircon process indicate the influences of reactor operationparameters on the plasma jet and particle behavior.
基金financially supported by the National Natural Science Foundation of China (20637020, 40490265 & 20077001)National Basic Research Program of China (2002CB410802)special fund of State Key Joint Laboratory of Environment Simulation and Pollution Control
文摘Urban and regional air pollutions are characterized by high concentrations of secondary pollutants such as photo-oxidants (mainly ozone) and fine particulate matter, which are formed through chemical reactions of the primary pollutants emitted from various sources. The accumulation of these pollutants under stagnant meteorological conditions results in the formation of gray haze, reducing visibility and causing major impacts on human health and climate. In an air pollution complex, the co- existence of high concentrations of primary and secondary gaseous and particulate pollutants provides a large amount of reac- tants for heterogeneous reactions on the surface of fine particles; these reactions change the oxidizing capacity of the atmos- phere, as well as chemical compositions along with the physicochemical and optical properties of particulate matter, thereby accelerating formation of the air pollution complex and gray haze. Using in situ technologies, such as diffuse reflectance infra- red Fourier-transform spectroscopy and single-particle Raman spectroscopy, we systematically investigated the reaction kinet- ics and mechanisms of gaseous pollutants (i.e., NO2, SO2, 03, and formaldehyde) on the surfaces of the major components of atmospheric particles such as CaCO3, kaolinite, montmorillonite, NaC1, sea salt, A1203, and Tit2. We found that the main re- action products were sulfate, nitrate, or formate, which can change the hygroscopicity and light extinction parameters of those particles significantly. By analyzing the reaction kinetics of these heterogeneous reactions, we identified synergetic mechanisms of the three ternary reaction systems, ,i.e., NOE-particles-H2O, SO2-particles-O3, and organics/SO2-particles-UV illumination. These synergetic mechanisms can provide experimental and theoretical bases for understanding the feedback mechanisms and nonlinear processes in the formation of an air pollution complex and gray haze.