In this paper, we combine polynomial functions, Generalized Estimating Equations, and bootstrap-based model selection to test for signatures of linear or nonlinear relationships between body surface temperature and am...In this paper, we combine polynomial functions, Generalized Estimating Equations, and bootstrap-based model selection to test for signatures of linear or nonlinear relationships between body surface temperature and ambient temperature in endotherms. Linearity or nonlinearity is associated with the absence or presence of cutaneous vasodilation and vasoconstriction, respectively. We obtained experimental data on body surface temperature variation from a mammalian model organism as a function of ambient temperature using infrared thermal imaging. The statistical framework of model estimation and selection successfully detected linear and nonlinear relationships between body surface temperature and ambient temperature for different body regions of the model organism. These results demonstrate that our statistical approach is instrumental to assess the complexity of thermoregulation in endotherms.展开更多
It is known that salt ions are abundant in the natural environment where natural gas hydrates are located;thus,it is essential to investigate the self-preservation effect of salt ions on methane hydrates.The dissociat...It is known that salt ions are abundant in the natural environment where natural gas hydrates are located;thus,it is essential to investigate the self-preservation effect of salt ions on methane hydrates.The dissociation behaviors of gas hydrates formed from various NaCl concentration solutions in a quartz sand system at 268.15 K were investigated to reveal the microscopic mechanism of the self-preservation effect under different salt concentrations.Results showed that as the salt concentration rises,the initial rate of hydrate decomposition quickens.Methane hydrate hardly shows self-preservation ability in the 3.35%(mass)NaCl and seawater systems at 268.15 K.Combined the morphology of hydrate observed by the confocal microscope with results obtained from in situ Raman spectroscopy,it was found that during the initial decomposition stage of gas hydrate below the ice point,gas hydrate firstly converts into liquid water and gas molecules,then turns from water to solid ice rather than directly transforming into solid ice and gas molecules.The presence of salt ions interferes with the ability of liquid water to condense into solid ice.The results of this study provide an important guide for the mechanism and application of the self-preservation effect on the storage and transport of gas and the exploitation of natural gas hydrates.展开更多
With the great impetus of energy conservation and emission reduction policies in various countries,the proposal of concepts such as“Sponge City”and“Eco-City”,and the emphasis on restoration and governance of ecolo...With the great impetus of energy conservation and emission reduction policies in various countries,the proposal of concepts such as“Sponge City”and“Eco-City”,and the emphasis on restoration and governance of ecological environment day by day,portland cement porous concrete(PCPC),as a novel building material,has attracted more and more attention from scientific researchers and engineers.PCPC possesses the peculiar pore structure,which owns numerous functions like river embankment protection,vegetation greening as well as air-cleaning,and has been of wide application in different engineering fields.This paper reviews the salient properties of PCPC,detailedly expounds the research progress of domestic and foreign literature about this subject in the past ten years(2010–2020),conducts the statistical analysis of the distribution rule of its major properties around the world,combines with the engineering application to summarize the excellent properties of PCPC,and makes a forecast of future research direction.展开更多
Dual endotherms during differenUal scanning calorimetric (DSC) measurement occur when dried PET pellets are pretreated with solld state polyeondensation (SSP) at 215-230℃ for appropriate holding, times. The two endot...Dual endotherms during differenUal scanning calorimetric (DSC) measurement occur when dried PET pellets are pretreated with solld state polyeondensation (SSP) at 215-230℃ for appropriate holding, times. The two endothermic fusion peaks arise from melting and recrystallization, taking place during scanning in the calorimeter,of imperfect crystals initial present in sample. The lower temperature peak appears higher than the SSP reaction temperature for 5-20℃ accordingly and linear relaflonship with SSP reaction temperature, logarithmic linear relationship vs. SSP reaction time, while the position of higher temperature peak nearly does not change. The higher the SSP reaction temperature, the larger the total area of the endotherms, namely, the higher crystallinity. For 4 reaction temperatures the crystallinity show logarithmic linear relationship vs, SSP reaction time.展开更多
Catalytic/initiated cracking of endothermic hydrocarbon fuels is an eff ective technology for cooling a hypersonic aircraft with a high Mach number(over 5).Catalysts and initiators can promote fuel cracking at low tem...Catalytic/initiated cracking of endothermic hydrocarbon fuels is an eff ective technology for cooling a hypersonic aircraft with a high Mach number(over 5).Catalysts and initiators can promote fuel cracking at low temperatures,increase fuel conversion and the heat sink capacity,and suppress coke deposition,thereby reducing waste heat.Catalysts mainly include metal oxide catalysts,noble metal catalysts and metal nanoparticles,zeolite catalysts,nanozeolite catalysts,and coating catalysts.Moreover,initiators roughly include nitrogenous compounds,oxygenated compounds,and hyperbranched polymer initiators.In this review,we aim to summarize the catalysts and initiators for cracking endothermic hydrocarbon fuels and their mechanisms for promoting cracking.This review will facilitate the development of the synthesis and exploration of catalysts and initiators.展开更多
Endothermic hydrocarbon fuels are advanced coolants for high-temperature structures of spacecraft. No data of tested-cooling-ability of endothermic fuels have been broadly discussed in literature. In this work a high-...Endothermic hydrocarbon fuels are advanced coolants for high-temperature structures of spacecraft. No data of tested-cooling-ability of endothermic fuels have been broadly discussed in literature. In this work a high-temperature flow calorimeter was designed, and the cooling capacity of six different hydrocarbon fuels were measured. Experimental results showed that these hydrocarbon fuels have capacity for cooling high-temperature structures, and that the cooling capacity of fuel N-1 can reach 3.15 M J/kg, which can nearly satisfy the requirement of thermal management for a Mach 3 cruise aircraft, whose heat sink requirement is about 3.5 M J/kg. The endothermic velocity of hydrocarbon fuels was also measured by the calorimeter.展开更多
Studies were carried out on the precipitation in two sets of binary Al-Li alloys by means of hardness tests,DSC analyses and TEM observations.When the alloys were aged for constant time,a peak appeared on the plot of ...Studies were carried out on the precipitation in two sets of binary Al-Li alloys by means of hardness tests,DSC analyses and TEM observations.When the alloys were aged for constant time,a peak appeared on the plot of temperature dependence upon their hardness in the range of low temperatures,and the endothermic dissolution peak was quite distinct on the DSC curve also at low temperatures.These are believed that an Li-rich GP zone formed in the al- loys aged at low temperatures,but no more GP zone if aging at elevated temperatures.The hardness of the alloys raises rapidly with coarsening of δ′-phase grains.The two endothermic peaks of δ′ dissolution on the DSC curve relate to the structural adjustment at twice of the δ′ precipitation.The equilibrium δ-phase,being of higher thermal stability,nucleates and grows directly from the supersaturated solid solution with the aid of the gram boundary.展开更多
The behaviors of Cu, Pb, and Zn during the endothermic burning of heterogeneous wastes were investigated using a variety of operational parameters, i.e., the mixed waste ratio, burning temperature, and burning time, t...The behaviors of Cu, Pb, and Zn during the endothermic burning of heterogeneous wastes were investigated using a variety of operational parameters, i.e., the mixed waste ratio, burning temperature, and burning time, to obtain fundamental knowledge to generate an optimal burning operation and recycling strategy for bottom ash. Changing these parameters had no impact on the Cu content of the ash, whereas the Pb content depended on the burning temperature and the mixed ratio, and the Zn content was affected by all three parameters. It was found in this study that the optimal burning conditions were a temperature of 1100?C, a time of 15 minutes, and either the current waste conditions or waste conditions with double the waste plastic and wood content.展开更多
Forest fires are one of the commonest natural hazards. Forest fires make the largest contribution to CO2 emissions after the burning of fossil fuels. Here a new technology is proposed to extinguish forest fires not wi...Forest fires are one of the commonest natural hazards. Forest fires make the largest contribution to CO2 emissions after the burning of fossil fuels. Here a new technology is proposed to extinguish forest fires not with water, but with a slurry of serpentine. Serpentinites are abundantly available in many countries on every continent. If serpentine is calcined, it weathers very fast and captures CO2. Calcination, however, requires a lot of heat, which makes it counterproductive to produce calcined serpentine for CO2 capture. In cases, however, where heat is the problem, like in forest fires, one can extinguish them to greater advantage by using serpentinite slurries instead of plain water. The calcined residue that is left as a thin cake on the burning material prevents oxygen to reach the burning material. It also prevents the escape of inflammable gases, and the calcination itself withdraws large quantities of heat from the fire. After the fire is extinguished, the calcined material in contact with the atmosphere will rapidly weather and capture CO2. This compensates part of the CO2 that is produced by the fire. In tests, where the efficacy of quenching fires with serpentine slurries was compared to the effect of water, it turned out that serpentinite slurries performed far better.展开更多
The selectivity behaviour of ion exchange resin Amberlite IR-120 for inorganic cations like sodium and potassium was predicted on the basis of thermodynamic data. The equilibrium constant K values calculated for uni-u...The selectivity behaviour of ion exchange resin Amberlite IR-120 for inorganic cations like sodium and potassium was predicted on the basis of thermodynamic data. The equilibrium constant K values calculated for uni-univalent ion exchange reaction systems were observed to increase with rise in temperature, indicating endothermic ion exchange reactions. From the K values calculated at different temperatures the enthalpy values were calculated. The low enthalpy and higher K values for K+ ion ex-change reaction indicates more affinity of the resin for potassium ions as compared to that for sodium ions also in the solution. The technique used in the present experimental work will be useful in understanding the selectivity behav-iour of different ion exchange resins for ions in the solution. Although the ionic selectivity data for the ion exchange resins is readily available in the literature, it is expected that the informa-tion obtained from the actual experimental trials will be more helpful. The technique used in the present experimental work when applied to dif-ferent ion exchange resins will help in there characterization.展开更多
Decalin is considered as an important compound of high-energy-density endothermic fuel,which is an ideal on-board coolant for thermal management of advanced aircraft.However,decalin contains two isomers with a tunable...Decalin is considered as an important compound of high-energy-density endothermic fuel,which is an ideal on-board coolant for thermal management of advanced aircraft.However,decalin contains two isomers with a tunable composition,and their effects on the pyrolysis performance,such as the heat sink and coking tendency have not been demonstrated.Herein,we investigated the pyrolysis of decalin isomers,i.e.,cis-decalin,trans-decalin and their mixtures(denoted as mix-decalin),in order to clarify the effects of the cis-/trans-structures on the pyrolysis performance of decalin fuels.The pyrolysis results confirmed that conversion of the tested fuels(600–725℃,4 MPa)decreased in the order cis-decalin>mix-decalin>trans-decalin.Detailed analyses of the pyrolysis products were used to compare the product distributions from cis-decalin,mix-decalin and trans-decalin,and the yields of some typical components(such as cyclohexene,1-methylcyclohexene,benzene and toluene)showed significant differences,which could be ascribed to deeper cracking of cis-decalin.Additionally,the heat sinks and coking tendencies of the decalins decreased in the order cis-decalin>mix-decalin>trans-decalin.This work demonstrates the relationship between the cis/trans structures and the pyrolysis performance of decalin,which provides a better understanding of the structure-activity relationships of endothermic hydrocarbon fuels.展开更多
The multiple endothermic peaks of poly（3-hydroxybutyrate-co-3-hydroxyvalerate） （P（HB-co-HV）） in differential scanning calorimetry （DSC） results, as one representative phenomenon of polymer with unique cocrysta...The multiple endothermic peaks of poly（3-hydroxybutyrate-co-3-hydroxyvalerate） （P（HB-co-HV）） in differential scanning calorimetry （DSC） results, as one representative phenomenon of polymer with unique cocrystallization behavior, were generally considered as the results of melting/recrystallization. In this study, wide angle X-ray diffraction （WAXD） and small angle X-ray scattering （SAXS） experiments were conducted to analyze the phenomena of multiple endothermic peaks in DSC results. The results of these analyses indicated that the multiple endotherms were mainly caused by different lamellae structures. For P（HB-co-HV） with lower HV content, it was comprised of two structures of HV total exclusion and HV partial inclusion in the crystal lamellae. For P（HB-co-HV） with higher HV content, it was also comprised of two structures of HV total inclusion and HV partial inclusion in the crystal lamellae. However, only structure with HV partial inclusion in the crystal lamellae remained existing after first melting peak for all samples.展开更多
Endothermic hydrocarbon fuel is regarded as an optimal fuel for a scramjet with regenerative cooling,which provides extra cooling through endothermic chemical conversion to avoid the severly limited cooling capacity w...Endothermic hydrocarbon fuel is regarded as an optimal fuel for a scramjet with regenerative cooling,which provides extra cooling through endothermic chemical conversion to avoid the severly limited cooling capacity when conventional fuels are adopted for cooling.Although endothermic cooling is proposed from the view point that the heat sink of a conventional fuel is insufficient,the heat-absorbing through endothermic chemical reaction is actually a chemical recuperation process because the wasted heat dissipated from the engine thermal structure is recovered through the endothermic chemical reaction.Therefore,the working process of a scramjet with endothermic hydrocarbon fuel cooling is a chemical recuperative cycle.To analyze the chemical recuperative cycle of a chemically recuperated scramjet engine,we defined physical and chemical recuperation effectivenesses and heating value increment rate,and derived engine performance parameters with chemical recuperation.The heat value benefits from both physical and chemical recuperations,and it increases with the increase in recuperation effectiveness.The scramjet performance parameters also increase with the increase in chemical recuperation effectiveness.The increase in chemical recuperation effectiveness improves both the performances of the fuel cooling system and the combustion system.The results of analysis prove that the existence of a chemical recuperation process greatly improves the performance of the whole scramjet.展开更多
How the structure and base composition of genes changed with the evolution of vertebrates remains a puzzling question. Here we analyzed 895 orthologous protein-coding genes in six multicellular animals： human, chicke...How the structure and base composition of genes changed with the evolution of vertebrates remains a puzzling question. Here we analyzed 895 orthologous protein-coding genes in six multicellular animals： human, chicken, zebrafish, sea squirt, fruit fly, and worm. Our analyses reveal that many gene regions, particularly intron and 3~ UTR, gradually expanded throughout the evolution of vertebrates from their invertebrate ancestors, and that the number of exons per gene increased. Studies based on all protein-coding genes in each genome provide consistent results. We also find that GC-content increased in many gene regions （especially 5＇ UTR） in the evolution of endotherms, except in coding-exons. Analysis of individual genomes shows that 3t UTR demonstrated stronger length and GC-content correlation with intron than 5~ UTR, and gene with large intron in all six species demonstrated relatively similar GC-content. Our data indicates a great increase in complexity in vertebrate genes and we propose that the requirement for morphological and functional changes is probably the driving force behind the evolution of structure and base composition complexity in multicellular animal genes.展开更多
Suspensoid of HZSM-5 or HY zeolites mixed with a self-made ceramic-like binder was coated on the inner wall of a tubular reactor by gas-aided fluid displacement technology.The coated zeolites were characterized by mea...Suspensoid of HZSM-5 or HY zeolites mixed with a self-made ceramic-like binder was coated on the inner wall of a tubular reactor by gas-aided fluid displacement technology.The coated zeolites were characterized by means of X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR)and scanning electron microscopy(SEM).The coating thickness is 10–20 mm and the particle size of the zeolites is in the range of 1–5 mm.In the coated reactor,cracking of endothermic fuels including n-dodecane and aviation fuel RP-3 was carried out separately under supercritical conditions at 600uC and 625uC to investigate their heat sinks and conversion of catalytic reactions.For the reaction catalyzed by HY(25%mass fraction)coating,the heat sink capacity of ndodecane are 815.7 and 901.9 kJ/kg higher than that of the bare tube at 600uC and at 625uC,respectively.Conversion of n-dodecane also increases from 42%to 60%at 600uC and from 66%to 80%at 625uC.The coated zeolite can significantly inhibit the carbon deposition during supercritical cracking reactions.展开更多
文摘In this paper, we combine polynomial functions, Generalized Estimating Equations, and bootstrap-based model selection to test for signatures of linear or nonlinear relationships between body surface temperature and ambient temperature in endotherms. Linearity or nonlinearity is associated with the absence or presence of cutaneous vasodilation and vasoconstriction, respectively. We obtained experimental data on body surface temperature variation from a mammalian model organism as a function of ambient temperature using infrared thermal imaging. The statistical framework of model estimation and selection successfully detected linear and nonlinear relationships between body surface temperature and ambient temperature for different body regions of the model organism. These results demonstrate that our statistical approach is instrumental to assess the complexity of thermoregulation in endotherms.
基金financial support received from the Basic Research Program of Qinghai Province(2023-ZJ-703)the National Natural Science Foundation of China(22178379,42206223)the National Key Research and Development Programof China(2021YFC2800902)is gratefully acknowledged.
文摘It is known that salt ions are abundant in the natural environment where natural gas hydrates are located;thus,it is essential to investigate the self-preservation effect of salt ions on methane hydrates.The dissociation behaviors of gas hydrates formed from various NaCl concentration solutions in a quartz sand system at 268.15 K were investigated to reveal the microscopic mechanism of the self-preservation effect under different salt concentrations.Results showed that as the salt concentration rises,the initial rate of hydrate decomposition quickens.Methane hydrate hardly shows self-preservation ability in the 3.35%(mass)NaCl and seawater systems at 268.15 K.Combined the morphology of hydrate observed by the confocal microscope with results obtained from in situ Raman spectroscopy,it was found that during the initial decomposition stage of gas hydrate below the ice point,gas hydrate firstly converts into liquid water and gas molecules,then turns from water to solid ice rather than directly transforming into solid ice and gas molecules.The presence of salt ions interferes with the ability of liquid water to condense into solid ice.The results of this study provide an important guide for the mechanism and application of the self-preservation effect on the storage and transport of gas and the exploitation of natural gas hydrates.
基金supported by the Jiangsu Water Conservancy Science and Technology Project of China(2016036).
文摘With the great impetus of energy conservation and emission reduction policies in various countries,the proposal of concepts such as“Sponge City”and“Eco-City”,and the emphasis on restoration and governance of ecological environment day by day,portland cement porous concrete(PCPC),as a novel building material,has attracted more and more attention from scientific researchers and engineers.PCPC possesses the peculiar pore structure,which owns numerous functions like river embankment protection,vegetation greening as well as air-cleaning,and has been of wide application in different engineering fields.This paper reviews the salient properties of PCPC,detailedly expounds the research progress of domestic and foreign literature about this subject in the past ten years(2010–2020),conducts the statistical analysis of the distribution rule of its major properties around the world,combines with the engineering application to summarize the excellent properties of PCPC,and makes a forecast of future research direction.
文摘Dual endotherms during differenUal scanning calorimetric (DSC) measurement occur when dried PET pellets are pretreated with solld state polyeondensation (SSP) at 215-230℃ for appropriate holding, times. The two endothermic fusion peaks arise from melting and recrystallization, taking place during scanning in the calorimeter,of imperfect crystals initial present in sample. The lower temperature peak appears higher than the SSP reaction temperature for 5-20℃ accordingly and linear relaflonship with SSP reaction temperature, logarithmic linear relationship vs. SSP reaction time, while the position of higher temperature peak nearly does not change. The higher the SSP reaction temperature, the larger the total area of the endotherms, namely, the higher crystallinity. For 4 reaction temperatures the crystallinity show logarithmic linear relationship vs, SSP reaction time.
基金supported by the National Natural Science Foundation of China(No.21978200).
文摘Catalytic/initiated cracking of endothermic hydrocarbon fuels is an eff ective technology for cooling a hypersonic aircraft with a high Mach number(over 5).Catalysts and initiators can promote fuel cracking at low temperatures,increase fuel conversion and the heat sink capacity,and suppress coke deposition,thereby reducing waste heat.Catalysts mainly include metal oxide catalysts,noble metal catalysts and metal nanoparticles,zeolite catalysts,nanozeolite catalysts,and coating catalysts.Moreover,initiators roughly include nitrogenous compounds,oxygenated compounds,and hyperbranched polymer initiators.In this review,we aim to summarize the catalysts and initiators for cracking endothermic hydrocarbon fuels and their mechanisms for promoting cracking.This review will facilitate the development of the synthesis and exploration of catalysts and initiators.
基金Project (No. 863-2-1-1-7) supported by the Hi-Tech Research and Development Program (863) of China
文摘Endothermic hydrocarbon fuels are advanced coolants for high-temperature structures of spacecraft. No data of tested-cooling-ability of endothermic fuels have been broadly discussed in literature. In this work a high-temperature flow calorimeter was designed, and the cooling capacity of six different hydrocarbon fuels were measured. Experimental results showed that these hydrocarbon fuels have capacity for cooling high-temperature structures, and that the cooling capacity of fuel N-1 can reach 3.15 M J/kg, which can nearly satisfy the requirement of thermal management for a Mach 3 cruise aircraft, whose heat sink requirement is about 3.5 M J/kg. The endothermic velocity of hydrocarbon fuels was also measured by the calorimeter.
文摘Studies were carried out on the precipitation in two sets of binary Al-Li alloys by means of hardness tests,DSC analyses and TEM observations.When the alloys were aged for constant time,a peak appeared on the plot of temperature dependence upon their hardness in the range of low temperatures,and the endothermic dissolution peak was quite distinct on the DSC curve also at low temperatures.These are believed that an Li-rich GP zone formed in the al- loys aged at low temperatures,but no more GP zone if aging at elevated temperatures.The hardness of the alloys raises rapidly with coarsening of δ′-phase grains.The two endothermic peaks of δ′ dissolution on the DSC curve relate to the structural adjustment at twice of the δ′ precipitation.The equilibrium δ-phase,being of higher thermal stability,nucleates and grows directly from the supersaturated solid solution with the aid of the gram boundary.
文摘The behaviors of Cu, Pb, and Zn during the endothermic burning of heterogeneous wastes were investigated using a variety of operational parameters, i.e., the mixed waste ratio, burning temperature, and burning time, to obtain fundamental knowledge to generate an optimal burning operation and recycling strategy for bottom ash. Changing these parameters had no impact on the Cu content of the ash, whereas the Pb content depended on the burning temperature and the mixed ratio, and the Zn content was affected by all three parameters. It was found in this study that the optimal burning conditions were a temperature of 1100?C, a time of 15 minutes, and either the current waste conditions or waste conditions with double the waste plastic and wood content.
文摘Forest fires are one of the commonest natural hazards. Forest fires make the largest contribution to CO2 emissions after the burning of fossil fuels. Here a new technology is proposed to extinguish forest fires not with water, but with a slurry of serpentine. Serpentinites are abundantly available in many countries on every continent. If serpentine is calcined, it weathers very fast and captures CO2. Calcination, however, requires a lot of heat, which makes it counterproductive to produce calcined serpentine for CO2 capture. In cases, however, where heat is the problem, like in forest fires, one can extinguish them to greater advantage by using serpentinite slurries instead of plain water. The calcined residue that is left as a thin cake on the burning material prevents oxygen to reach the burning material. It also prevents the escape of inflammable gases, and the calcination itself withdraws large quantities of heat from the fire. After the fire is extinguished, the calcined material in contact with the atmosphere will rapidly weather and capture CO2. This compensates part of the CO2 that is produced by the fire. In tests, where the efficacy of quenching fires with serpentine slurries was compared to the effect of water, it turned out that serpentinite slurries performed far better.
文摘The selectivity behaviour of ion exchange resin Amberlite IR-120 for inorganic cations like sodium and potassium was predicted on the basis of thermodynamic data. The equilibrium constant K values calculated for uni-univalent ion exchange reaction systems were observed to increase with rise in temperature, indicating endothermic ion exchange reactions. From the K values calculated at different temperatures the enthalpy values were calculated. The low enthalpy and higher K values for K+ ion ex-change reaction indicates more affinity of the resin for potassium ions as compared to that for sodium ions also in the solution. The technique used in the present experimental work will be useful in understanding the selectivity behav-iour of different ion exchange resins for ions in the solution. Although the ionic selectivity data for the ion exchange resins is readily available in the literature, it is expected that the informa-tion obtained from the actual experimental trials will be more helpful. The technique used in the present experimental work when applied to dif-ferent ion exchange resins will help in there characterization.
基金support from the National Key R&D Program of China(Grant No.2021YFC2103701)the Haihe Laboratory of Sustainable Chemical Transformations for financial support,the Postdoctoral Science Foundation of China(Grant No.2021M702810)the National Natural Science Foundation of China(Grant No.22208295)。
文摘Decalin is considered as an important compound of high-energy-density endothermic fuel,which is an ideal on-board coolant for thermal management of advanced aircraft.However,decalin contains two isomers with a tunable composition,and their effects on the pyrolysis performance,such as the heat sink and coking tendency have not been demonstrated.Herein,we investigated the pyrolysis of decalin isomers,i.e.,cis-decalin,trans-decalin and their mixtures(denoted as mix-decalin),in order to clarify the effects of the cis-/trans-structures on the pyrolysis performance of decalin fuels.The pyrolysis results confirmed that conversion of the tested fuels(600–725℃,4 MPa)decreased in the order cis-decalin>mix-decalin>trans-decalin.Detailed analyses of the pyrolysis products were used to compare the product distributions from cis-decalin,mix-decalin and trans-decalin,and the yields of some typical components(such as cyclohexene,1-methylcyclohexene,benzene and toluene)showed significant differences,which could be ascribed to deeper cracking of cis-decalin.Additionally,the heat sinks and coking tendencies of the decalins decreased in the order cis-decalin>mix-decalin>trans-decalin.This work demonstrates the relationship between the cis/trans structures and the pyrolysis performance of decalin,which provides a better understanding of the structure-activity relationships of endothermic hydrocarbon fuels.
基金financially supported by Natural Science Foundation of Zhejiang Province(No.LY15B040003)K.C.Wong Magna Fund in Ningbo University
文摘The multiple endothermic peaks of poly（3-hydroxybutyrate-co-3-hydroxyvalerate） （P（HB-co-HV）） in differential scanning calorimetry （DSC） results, as one representative phenomenon of polymer with unique cocrystallization behavior, were generally considered as the results of melting/recrystallization. In this study, wide angle X-ray diffraction （WAXD） and small angle X-ray scattering （SAXS） experiments were conducted to analyze the phenomena of multiple endothermic peaks in DSC results. The results of these analyses indicated that the multiple endotherms were mainly caused by different lamellae structures. For P（HB-co-HV） with lower HV content, it was comprised of two structures of HV total exclusion and HV partial inclusion in the crystal lamellae. For P（HB-co-HV） with higher HV content, it was also comprised of two structures of HV total inclusion and HV partial inclusion in the crystal lamellae. However, only structure with HV partial inclusion in the crystal lamellae remained existing after first melting peak for all samples.
基金supported by the National Natural Science Foundation of China (General Program) (Grant No. 51106037)the Distinguished Young Scholars (Grant No. 50925625)the Innovative Research Groups(Grant No. 51121004)
文摘Endothermic hydrocarbon fuel is regarded as an optimal fuel for a scramjet with regenerative cooling,which provides extra cooling through endothermic chemical conversion to avoid the severly limited cooling capacity when conventional fuels are adopted for cooling.Although endothermic cooling is proposed from the view point that the heat sink of a conventional fuel is insufficient,the heat-absorbing through endothermic chemical reaction is actually a chemical recuperation process because the wasted heat dissipated from the engine thermal structure is recovered through the endothermic chemical reaction.Therefore,the working process of a scramjet with endothermic hydrocarbon fuel cooling is a chemical recuperative cycle.To analyze the chemical recuperative cycle of a chemically recuperated scramjet engine,we defined physical and chemical recuperation effectivenesses and heating value increment rate,and derived engine performance parameters with chemical recuperation.The heat value benefits from both physical and chemical recuperations,and it increases with the increase in recuperation effectiveness.The scramjet performance parameters also increase with the increase in chemical recuperation effectiveness.The increase in chemical recuperation effectiveness improves both the performances of the fuel cooling system and the combustion system.The results of analysis prove that the existence of a chemical recuperation process greatly improves the performance of the whole scramjet.
基金supported by the National Natural Science Foundation of China(Nos.30930049 and 30870176(gsl))to D.T.or J-Q.C
文摘How the structure and base composition of genes changed with the evolution of vertebrates remains a puzzling question. Here we analyzed 895 orthologous protein-coding genes in six multicellular animals： human, chicken, zebrafish, sea squirt, fruit fly, and worm. Our analyses reveal that many gene regions, particularly intron and 3~ UTR, gradually expanded throughout the evolution of vertebrates from their invertebrate ancestors, and that the number of exons per gene increased. Studies based on all protein-coding genes in each genome provide consistent results. We also find that GC-content increased in many gene regions （especially 5＇ UTR） in the evolution of endotherms, except in coding-exons. Analysis of individual genomes shows that 3t UTR demonstrated stronger length and GC-content correlation with intron than 5~ UTR, and gene with large intron in all six species demonstrated relatively similar GC-content. Our data indicates a great increase in complexity in vertebrate genes and we propose that the requirement for morphological and functional changes is probably the driving force behind the evolution of structure and base composition complexity in multicellular animal genes.
文摘Suspensoid of HZSM-5 or HY zeolites mixed with a self-made ceramic-like binder was coated on the inner wall of a tubular reactor by gas-aided fluid displacement technology.The coated zeolites were characterized by means of X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR)and scanning electron microscopy(SEM).The coating thickness is 10–20 mm and the particle size of the zeolites is in the range of 1–5 mm.In the coated reactor,cracking of endothermic fuels including n-dodecane and aviation fuel RP-3 was carried out separately under supercritical conditions at 600uC and 625uC to investigate their heat sinks and conversion of catalytic reactions.For the reaction catalyzed by HY(25%mass fraction)coating,the heat sink capacity of ndodecane are 815.7 and 901.9 kJ/kg higher than that of the bare tube at 600uC and at 625uC,respectively.Conversion of n-dodecane also increases from 42%to 60%at 600uC and from 66%to 80%at 625uC.The coated zeolite can significantly inhibit the carbon deposition during supercritical cracking reactions.
