Antarctic krill(Euphausia superba)oil has been gaining increasing attention due to its nutritional and functional potentials.Krill oil usually contains a high concentration(about 50%)of phospholipids(AKOP)rich in DHA ...Antarctic krill(Euphausia superba)oil has been gaining increasing attention due to its nutritional and functional potentials.Krill oil usually contains a high concentration(about 50%)of phospholipids(AKOP)rich in DHA and EPA accompanied with 30%–40%triacylglycerols.Phospholipids can be made into liposomes without emulsifiers due to its amphiphilic characteristics.However,the absorption kinetics of AKOP liposome in vivo is not clear,which restrict the molecular mechanism analysis related to its distinct bioactivities.The lipid analysis in serum,small intestinal content and wall was carried out after oral administration of AKOP liposome to illustrate its absorption kinetics in blood and the digestive tract of healthy mice by single gavage.The major type of the obtained AKOP was phosphatidylcholine,and the total contents of the DHA and EPA were 29.31%.AKOP liposome was almost completely digested in the small intestine in 1 h and the hydrolysis products could be quickly absorbed by intestinal enterocytes.The DHA in serum peaked at 2 h after administration of AKOP liposome.AKOP liposome could be quickly digested and absorbed in vivo.The obtained results might provide a scientific basis for the molecular mechanism analysis related to distinct bioactivities of Antarctic krill oil phospholipid.展开更多
Recovery of carbon monoxide from flue gases by selective absorption of carbon monoxide in an imidazolium chlorocuprate（l） ionic liquid is considered in this work as an alternative to the use of molecular volatile so...Recovery of carbon monoxide from flue gases by selective absorption of carbon monoxide in an imidazolium chlorocuprate（l） ionic liquid is considered in this work as an alternative to the use of molecular volatile solvents such as aromatic hydrocarbons. The present work evaluates the CO mass transfer rates from the gas phase to the ionic liquid solutions in the absence of chemical reaction. To that end, carbon dioxide was employed as an inert model gas and absorption experiments were performed to assess the influence of different process variables in a batch reactor with fiat gas-liquid interface. The experimental mass transfer coefficients showed significant var- iation with temperature, （3.4-10.9） × 10^-7 m·s^-1 between 293 and 313 K; stirring speed, （10.2- 33.1）× 10^-7 m.s 1 between 100 and 300 r·min^-1; and concentration of copper（1）, （6.6-10.2） × 10^-7 m·s^-1 between 0.25 and 2 mol· L^- 1. In addition, the mass transfer coefficients were eventually found to follow a poten- tial proportionality of the type kL ∝μ^-0.5 and the dimensionless correlation that makes the estimation of the mass transfer coefficients possible in the studied range of process variables was obtained： Sh=10^-2.64 Re^1.07 , Sc^0.75,These results constitute the first step in the kinetic analysis of the reaction between CO and imidazolium chlorocuprate（I） ionic liquid that determines the design of the separation units.展开更多
We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microsc...We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.展开更多
Based on 15N tracer technique,absorption of different concentrations of ammonium nitrogen(N-NH^(4+)),nitrate nitrogen(N-NO^(3-))and glycine(NGly)by root of six species of alpine forage(Puccinellia tenuiflora,Poa crymo...Based on 15N tracer technique,absorption of different concentrations of ammonium nitrogen(N-NH^(4+)),nitrate nitrogen(N-NO^(3-))and glycine(NGly)by root of six species of alpine forage(Puccinellia tenuiflora,Poa crymophila,Festuca sinensis,Elymus nutans,Elymus sibiricus and Bromus inermis)was studied in a hydroponic culture.The uptake kinetic parameter was analyzed according to Michaelis-Menten equation.The Michaelis-Menten equation represents the velocity equation for the relationship between the initial rate of an enzymatic reaction and the substrate concentration.The result showed that the absorption range of ammonium nitrogen,nitrate nitrogen and glycine by root of six species of alpine plant were 1.1-20.9μmol·g^(-1)·h^(-1),0.4-3.4μmol·g^(-1)·h^(-1) and 0.1-3.7μmol·g^(-1)·h^(-1),which accounts for 68.8%-74.7%,12.0%-27.0%and 4.3%-13.4%of total absorptivity,respectively.The six kinds of P.tenuiflora,P.crymophila,F.sinensis,E.nutans,E.sibiricus and B.inermis showed significant difference in nitrogen absorption.At the same concentration,the absorption of nitrogen in different forms of the same herbage is different.The absorptive amount of ammonium nitrogen was the highest among them,then the glycine,the nitrate nitrogen was least absorbed.The results could provide a theoretical basis for nitrogen utilization in alpine forages.For example,P.tenuiflora showed a much higher ability of absorbing nitrogen nutrition in a high salt environment and could be a more suitable herbage to be planted in saline-alkali soil in the Qinghai-Tibet Plateau as compared with E.nutans.展开更多
Magnesium hydride,as an important light-metal hydrogen storage material for on-board hydrogen storage,aerospace,and energy fields,has long been limited in its large-scale applications by slow hydrogen storage speed an...Magnesium hydride,as an important light-metal hydrogen storage material for on-board hydrogen storage,aerospace,and energy fields,has long been limited in its large-scale applications by slow hydrogen storage speed and high dehydrogenation temperature.In this work,ultra-stable bimetallic MXene Mo_(2)V_(2)C_(3)was successfully synthesized and used to accelerate the hydrogen storage speed and reduce the dehydrogenation/hydrogenation temperature of MgH_(2).The MgH_(2)+10 wt%Mo_(2)V_(2)C_(3)sample starts dehydrogenation at 180℃and reaches the maximum dehydrogenation rate at 259℃.It also exhibits outstanding room-temperature(RT)rapid hydrogenation performance and cycling stability,retaining up to 100%capacity after 50 cycles at 300℃.Another interesting phenomenon is that the hydrogen storage speed of the sample is even faster without capacity decrease as the dehydrogenation/re-hydrogena tion cycle proceeds.First-principles calculations show that the Mg atoms are stabilized at the top sites of Mo atoms,and the Mg-H bonds that are adsorbed on Mo_(2)V_(2)C_(3)are more susceptible to breakage.The key to the accelerated rate of Mg/MgH_(2)hydrogenation/dehydrogenation is the enhancement of the interaction between Mg/MgH_(2)and Mo_(2)V_(2)C_(3)MXene with the increasing number of cycles,whereas the existence of the V renders the structure of MXene more stable.Our study refines the mechanistic understanding of bimetallic MXene catalyst for MgH_(2)hydrogen storage and expands reference on the type and preparation of bimetallic MXene.展开更多
As-cast and rapidly solidified Ti_(23)V_(40)Mn_(37)alloy doped with Zr_(7)Ni_(10) was synthesized by arc melting and melt-spinning.The microstructure,activation property,hydrogen absorption kinetics,and hydrogen absor...As-cast and rapidly solidified Ti_(23)V_(40)Mn_(37)alloy doped with Zr_(7)Ni_(10) was synthesized by arc melting and melt-spinning.The microstructure,activation property,hydrogen absorption kinetics,and hydrogen absorption/desorption thermodynamics were investigated to evaluate a comprehensive hydrogen storage property of the alloys.Both preparation methods had a negligible effect on the lattice parameter of BCC and C14 Laves phases in the alloys.The alloy prepared by melt-spinning showed an increased proportion of BCC phase,larger hydrogen absorption capacity,faster hydrogen absorption rate,and higher hydrogen absorption/desorption platform pressure.The dehydriding enthalpy and endothermic peak temperature of the rapidly solidified alloy were 33.55±2.14 KJ/mol H_(2)and 526.2 K,respectively,which are smaller than those of the as-cast alloy.It indicates the decreased hydride stability and improved hydrogen desorption property.By contrast with the as-cast alloy,the rapidly solidified alloy showed a preferable comprehensive hydrogen storage property.展开更多
The bulk Ti-6Al-4V alloy was hydrogenated at the temperature range of 723-973 K,and the hydrogen absorption characteristics and hydrogen absorption kinetics were investigated.The results show that there are two types ...The bulk Ti-6Al-4V alloy was hydrogenated at the temperature range of 723-973 K,and the hydrogen absorption characteristics and hydrogen absorption kinetics were investigated.The results show that there are two types of hydrogen absorption characteristics at different temperatures.The hydrogen content decreases,and the time reaching reaction equilibrium is shorten with the isothermal hydrogenation temperature increasing.Meanwhile,the mechanism of the hydrogen absorption kinetics is different at different temperatures.The incubation period exists at the initial hydrogen absorption stage below 823 K,and K(a2)(the reaction rate constant of Stage 2)>>K(a1)(the reaction rate constant of Stage 1).And there is no incubation period over 823 K,K(a1)>>K(a2).展开更多
Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dyna...Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.展开更多
The new organic-inorganic compound, [C_6H_7N_2O_2]_3TeCl_5·2Cl was synthesized and its structure was determined at room temperature in the triclinic system （P^-1） with the following parameters： a = 10.5330（11...The new organic-inorganic compound, [C_6H_7N_2O_2]_3TeCl_5·2Cl was synthesized and its structure was determined at room temperature in the triclinic system （P^-1） with the following parameters： a = 10.5330（11） ？, b = 10.6663（11） ？, c = 15.9751（16）？, α = 82.090（2）°, β = 71.193（2）°, γ = 68.284（2）°and Z = 2. The final cycle of refinement led to R = 0.057 and Rw = 0.149. The crystal structure was stabilized by an extensive network of N--H···Cl and non-classical C--H···Cl hydrogen bonds between the cation and the anionic group. Several thermal analysis techniques such as thermogravimetric analysis, differential scanning calorimetric analysis and evolved gas analysis were used. We used isoconversional kinetics methods to determine the kinetics parameters. We observe that the decomposition of [C_6H_7N_2O_2]_3TeCl_5·2Cl entails the formation hydrochloric acid of nitroaniline as volatiles. The infrared spectra were recorded in the4000–400 cm^（-1）frequency region. The Raman spectra were recorded in the external region of the anionic sublattice vibration 50–1500 cm^（-1）. The optical band gap was calculated from the UV-Vis absorbance spectra using classical Tauc relation which was found to be 3.12 and 3.67 eV.展开更多
文摘Antarctic krill(Euphausia superba)oil has been gaining increasing attention due to its nutritional and functional potentials.Krill oil usually contains a high concentration(about 50%)of phospholipids(AKOP)rich in DHA and EPA accompanied with 30%–40%triacylglycerols.Phospholipids can be made into liposomes without emulsifiers due to its amphiphilic characteristics.However,the absorption kinetics of AKOP liposome in vivo is not clear,which restrict the molecular mechanism analysis related to its distinct bioactivities.The lipid analysis in serum,small intestinal content and wall was carried out after oral administration of AKOP liposome to illustrate its absorption kinetics in blood and the digestive tract of healthy mice by single gavage.The major type of the obtained AKOP was phosphatidylcholine,and the total contents of the DHA and EPA were 29.31%.AKOP liposome was almost completely digested in the small intestine in 1 h and the hydrolysis products could be quickly absorbed by intestinal enterocytes.The DHA in serum peaked at 2 h after administration of AKOP liposome.AKOP liposome could be quickly digested and absorbed in vivo.The obtained results might provide a scientific basis for the molecular mechanism analysis related to distinct bioactivities of Antarctic krill oil phospholipid.
基金the projects ENE2010-15585 and CTQ2012-31639the FPI postgraduate research grant(BES-2011-046279)
文摘Recovery of carbon monoxide from flue gases by selective absorption of carbon monoxide in an imidazolium chlorocuprate（l） ionic liquid is considered in this work as an alternative to the use of molecular volatile solvents such as aromatic hydrocarbons. The present work evaluates the CO mass transfer rates from the gas phase to the ionic liquid solutions in the absence of chemical reaction. To that end, carbon dioxide was employed as an inert model gas and absorption experiments were performed to assess the influence of different process variables in a batch reactor with fiat gas-liquid interface. The experimental mass transfer coefficients showed significant var- iation with temperature, （3.4-10.9） × 10^-7 m·s^-1 between 293 and 313 K; stirring speed, （10.2- 33.1）× 10^-7 m.s 1 between 100 and 300 r·min^-1; and concentration of copper（1）, （6.6-10.2） × 10^-7 m·s^-1 between 0.25 and 2 mol· L^- 1. In addition, the mass transfer coefficients were eventually found to follow a poten- tial proportionality of the type kL ∝μ^-0.5 and the dimensionless correlation that makes the estimation of the mass transfer coefficients possible in the studied range of process variables was obtained： Sh=10^-2.64 Re^1.07 , Sc^0.75,These results constitute the first step in the kinetic analysis of the reaction between CO and imidazolium chlorocuprate（I） ionic liquid that determines the design of the separation units.
基金Financial supports by the National Natural Science Foundation of China (No. 21373269)the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(No. 10XNJ047)
文摘We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.
基金This work was supported in parts by the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(2019QZKK0302)Qinghai Provinceʼs first batch of special funds for the central government to guide local scientific and technological development in 2021(2021ZY002)the National Natural Sciences Foundation of China(41761107).
文摘Based on 15N tracer technique,absorption of different concentrations of ammonium nitrogen(N-NH^(4+)),nitrate nitrogen(N-NO^(3-))and glycine(NGly)by root of six species of alpine forage(Puccinellia tenuiflora,Poa crymophila,Festuca sinensis,Elymus nutans,Elymus sibiricus and Bromus inermis)was studied in a hydroponic culture.The uptake kinetic parameter was analyzed according to Michaelis-Menten equation.The Michaelis-Menten equation represents the velocity equation for the relationship between the initial rate of an enzymatic reaction and the substrate concentration.The result showed that the absorption range of ammonium nitrogen,nitrate nitrogen and glycine by root of six species of alpine plant were 1.1-20.9μmol·g^(-1)·h^(-1),0.4-3.4μmol·g^(-1)·h^(-1) and 0.1-3.7μmol·g^(-1)·h^(-1),which accounts for 68.8%-74.7%,12.0%-27.0%and 4.3%-13.4%of total absorptivity,respectively.The six kinds of P.tenuiflora,P.crymophila,F.sinensis,E.nutans,E.sibiricus and B.inermis showed significant difference in nitrogen absorption.At the same concentration,the absorption of nitrogen in different forms of the same herbage is different.The absorptive amount of ammonium nitrogen was the highest among them,then the glycine,the nitrate nitrogen was least absorbed.The results could provide a theoretical basis for nitrogen utilization in alpine forages.For example,P.tenuiflora showed a much higher ability of absorbing nitrogen nutrition in a high salt environment and could be a more suitable herbage to be planted in saline-alkali soil in the Qinghai-Tibet Plateau as compared with E.nutans.
基金supported by the National Key Research and Development Plan(2023YFB3809101)the National Natural Science Foundation of China(Grant nos.52471225,52201250,52271212,52401277)+1 种基金the Fundamental Research Funds for the Central Universities(2024MS084)the Double-First Class project for the NCEPU。
文摘Magnesium hydride,as an important light-metal hydrogen storage material for on-board hydrogen storage,aerospace,and energy fields,has long been limited in its large-scale applications by slow hydrogen storage speed and high dehydrogenation temperature.In this work,ultra-stable bimetallic MXene Mo_(2)V_(2)C_(3)was successfully synthesized and used to accelerate the hydrogen storage speed and reduce the dehydrogenation/hydrogenation temperature of MgH_(2).The MgH_(2)+10 wt%Mo_(2)V_(2)C_(3)sample starts dehydrogenation at 180℃and reaches the maximum dehydrogenation rate at 259℃.It also exhibits outstanding room-temperature(RT)rapid hydrogenation performance and cycling stability,retaining up to 100%capacity after 50 cycles at 300℃.Another interesting phenomenon is that the hydrogen storage speed of the sample is even faster without capacity decrease as the dehydrogenation/re-hydrogena tion cycle proceeds.First-principles calculations show that the Mg atoms are stabilized at the top sites of Mo atoms,and the Mg-H bonds that are adsorbed on Mo_(2)V_(2)C_(3)are more susceptible to breakage.The key to the accelerated rate of Mg/MgH_(2)hydrogenation/dehydrogenation is the enhancement of the interaction between Mg/MgH_(2)and Mo_(2)V_(2)C_(3)MXene with the increasing number of cycles,whereas the existence of the V renders the structure of MXene more stable.Our study refines the mechanistic understanding of bimetallic MXene catalyst for MgH_(2)hydrogen storage and expands reference on the type and preparation of bimetallic MXene.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.51674201)the Natural Science Foundation of Shaanxi Province(Grant No.2020JQ-906).
文摘As-cast and rapidly solidified Ti_(23)V_(40)Mn_(37)alloy doped with Zr_(7)Ni_(10) was synthesized by arc melting and melt-spinning.The microstructure,activation property,hydrogen absorption kinetics,and hydrogen absorption/desorption thermodynamics were investigated to evaluate a comprehensive hydrogen storage property of the alloys.Both preparation methods had a negligible effect on the lattice parameter of BCC and C14 Laves phases in the alloys.The alloy prepared by melt-spinning showed an increased proportion of BCC phase,larger hydrogen absorption capacity,faster hydrogen absorption rate,and higher hydrogen absorption/desorption platform pressure.The dehydriding enthalpy and endothermic peak temperature of the rapidly solidified alloy were 33.55±2.14 KJ/mol H_(2)and 526.2 K,respectively,which are smaller than those of the as-cast alloy.It indicates the decreased hydride stability and improved hydrogen desorption property.By contrast with the as-cast alloy,the rapidly solidified alloy showed a preferable comprehensive hydrogen storage property.
基金financially supported by Sichuan Province Science and Technology Project (No.2013VTZC04)
文摘The bulk Ti-6Al-4V alloy was hydrogenated at the temperature range of 723-973 K,and the hydrogen absorption characteristics and hydrogen absorption kinetics were investigated.The results show that there are two types of hydrogen absorption characteristics at different temperatures.The hydrogen content decreases,and the time reaching reaction equilibrium is shorten with the isothermal hydrogenation temperature increasing.Meanwhile,the mechanism of the hydrogen absorption kinetics is different at different temperatures.The incubation period exists at the initial hydrogen absorption stage below 823 K,and K(a2)(the reaction rate constant of Stage 2)>>K(a1)(the reaction rate constant of Stage 1).And there is no incubation period over 823 K,K(a1)>>K(a2).
基金supported by the National Natural Science Foundation of China (51639007)the Youth Science and Technology Fund of Sichuan Province (2016JQ0011)the Science and Technology Fund of Chengdu Water Authority (14H1055).
文摘Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.
基金partially funded by the Tunisian Ministry of Higher Education and Scientific Research,the Spanish Programa Nacional de Materiales through project MAT2014-51778-C2-2-Rby the Universitat de Girona contract No.MPCUd G2016/059.Dfinancial support of the Tunisian Ministry of Higher Education and Scientific Research
文摘The new organic-inorganic compound, [C_6H_7N_2O_2]_3TeCl_5·2Cl was synthesized and its structure was determined at room temperature in the triclinic system （P^-1） with the following parameters： a = 10.5330（11） ？, b = 10.6663（11） ？, c = 15.9751（16）？, α = 82.090（2）°, β = 71.193（2）°, γ = 68.284（2）°and Z = 2. The final cycle of refinement led to R = 0.057 and Rw = 0.149. The crystal structure was stabilized by an extensive network of N--H···Cl and non-classical C--H···Cl hydrogen bonds between the cation and the anionic group. Several thermal analysis techniques such as thermogravimetric analysis, differential scanning calorimetric analysis and evolved gas analysis were used. We used isoconversional kinetics methods to determine the kinetics parameters. We observe that the decomposition of [C_6H_7N_2O_2]_3TeCl_5·2Cl entails the formation hydrochloric acid of nitroaniline as volatiles. The infrared spectra were recorded in the4000–400 cm^（-1）frequency region. The Raman spectra were recorded in the external region of the anionic sublattice vibration 50–1500 cm^（-1）. The optical band gap was calculated from the UV-Vis absorbance spectra using classical Tauc relation which was found to be 3.12 and 3.67 eV.
