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
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
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
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.
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.
