Three yearling lambs with a rumen cannula were used to investigate the effects of supplementation with an urea-minerals lick block （ULB） on the kinetics of ruminal fibre digestion, nutrient digestibility and nitrog...Three yearling lambs with a rumen cannula were used to investigate the effects of supplementation with an urea-minerals lick block （ULB） on the kinetics of ruminal fibre digestion, nutrient digestibility and nitrogen （N） utilization office straw （RS）, ammonia bicarbonate （AB）-treated RS （ABRS） and hay prepared from natural pasture. The digestibility of dry matter and organic matter of RS increased by 13.1% and 12.7% （P〈0.05） when the diet was supplemented with ULB, and approached to that of ABRS, indicating that the effect of ULB on digestibility of RS is similar to that of AB treatment. The digestibility of ABRS was slightly improved by the ULB feeding. Nitrogen retention was highest in lambs fed on ABRS alone, followed by hay with ULB, and was lowest in animals fed on RS with ULB. However, both the amount and proportion of N retention to N intake were enhanced by ULB supplementation to lambs fed on hay. The proportion of N retained to N digested decreased due to ULB supplementation to lambs fed on RS or ABRS. Supplementing ULB did not greatly influence the rumen degradation of either dry matter or crude protein in each of the three diets. RS and hay had similar values in the potential extent of digestion （PED） and digestion rate of PED （kd） of fibrous materials, but the discrete lag time for RS was lower than that for hay. The AB treatment significantly increased the PED （P〈0.05） and kd （P〈0.05） of RS. Neither the PED nor kd for RS and ABRS was influenced by ULB supplementation, but the kd for hay significantly increased due to ULB. The lag time for hay was also shortened by the ULB feeding. The ULB improved the digestion of fibre in the rumen of lambs fed on low quality roughage. It is inferred that while ULB is effective in increasing nutrient digestibility of low quality roughages by improving ruminal fibre digestion. A synchronized supply of N and energy to rumen microbes should be considered to improve the efficiency of N utilization when the basal diet is ammoniated straw.展开更多
Based on the statistical analysis of blocking effect arising from anisotropic growth,the anisotropic effect on the kinetics of solid-state transformation was investigated.The result shows that the blocking effect lead...Based on the statistical analysis of blocking effect arising from anisotropic growth,the anisotropic effect on the kinetics of solid-state transformation was investigated.The result shows that the blocking effect leads to the retardation of transformation and then a regular behavior of varying Avrami exponent.Following previous analytical model,the formulations of Avrami exponent and effective activation energy accounting for blocking effect were obtained.The anisotropic effect on the transformation depends on two factors,non-blocking factor γ and blocking scale k,which directly acts on the dimensionality of growth.The effective activation energy is not affected by the anisotropic effect.The evolution of anisotropic effect with the fraction transformed is taken into account,showing that the anisotropic effect is more severe at the middle stage of transformation.展开更多
Room-temperature sodium-sulfur(RT Na-S)batteries hold great promise for large-scale energy storage applications owing to the high energy density and earth-abundance of Na and S.However,the dissolution and migration of...Room-temperature sodium-sulfur(RT Na-S)batteries hold great promise for large-scale energy storage applications owing to the high energy density and earth-abundance of Na and S.However,the dissolution and migration of sodium polysulfides,uncontrollable Na dendrite growth,and the lack of studies on Na electrodeposition kinetics have hindered the development of these batteries.Herein,we reveal the mechanism of sodium polysulfides on the Na plating/stripping kinetics using a three-electrode system.First,the kinetic behavior deviates from the commonly supposed Butler-Volmer model,which is well described by the Marcus model.In addition,the specific adsorption of polysulfides on the sodium electrode surface is a key factor influencing the kinetics.Higher-order polysulfides(S_(8)^(2-)and S_(6)^(2-))exhibit distinct specific adsorption behaviors because of their high adsorption energies compared to lower-order polysulfides(S_(4)^(2-)and S_(2)^(2-)).The electrostatic effect caused by specific adsorption can accelerate the kinetics,whereas the blocking effect can slow the kinetics.Thus,this competitive relationship enables low concentrations of high-order polysulfides to stimulate kinetics.This implies that a weak shuttle effect is beneficial for obtaining a stable Na deposition in RT Na-S batteries.An in-depth understanding of the Na electrodeposition kinetics provides beneficial clues for future metal sodium/electrolyte interface designs.展开更多
During winter, ice jams develop when floating ice blocks accumulate in rivers. Ice jams can dramatically decrease in the capacity of flow in a river and can cause ice flooding due to increase in water level. Submergen...During winter, ice jams develop when floating ice blocks accumulate in rivers. Ice jams can dramatically decrease in the capacity of flow in a river and can cause ice flooding due to increase in water level. Submergence of floating ice blocks in front of ice cover is critical for the development of an ice jam. In this study, the effect of the rotation angle of ice blocks on the submergence of ice block was assessed. The impacts of both the drag force caused by the flow and the hydraulic pressure force on the rotation of ice block were studied. Considering both the maximum moment for anti-overturn of an ice block, and the associated rotation angle </span><i><span style="font-family:Verdana;">θ</span></i><sub><span style="font-family:Verdana;font-size:12px;">1</span></sub><span style="font-family:Verdana;">, equations for describing the criteria for ice block entrainment in front of ice cover have been derived. On the basis of the theorem for moment equilibrium, relating the moment acting on a horizontal ice block with the maximum anti-overturn moment of an ice block, the criteria for assessing the overturn-and-submergence of an ice block have been proposed. To verify results using the derived equations for calculating the critical flow velocity for ice block submergence in front of ice cover, data was collected from flume experiments in the laboratory. Experiments have been conducted using different sizes of ice block under different flow conditions in a flume which is 26.68 m long, 0.40 m wide, and 0.6 m deep. Model ice blocks were </span><span style="font-family:Verdana;">made of polypropylene </span><span style="font-family:Verdana;">and have</span><span style="font-family:Verdana;"> nearly the same as the mass density of the nat</span><span style="font-family:Verdana;">ural ice. Using proposed method for assessing ice block submergence in front of ice cover, calculated critical flow velocities agree well with those of experi</span><span style="font-family:Verdana;">ments.展开更多
The nonisothermal crystallization kinetics of PEEK-PEDEK block copolymers was studied and the results showed that the Avrami exponent n of each sample was generally larger than 3, which indicates the initial crystalli...The nonisothermal crystallization kinetics of PEEK-PEDEK block copolymers was studied and the results showed that the Avrami exponent n of each sample was generally larger than 3, which indicates the initial crystallization of the complex. The crystallization behavior could be described as heterogeneous, multi-dimensional spherical growth with thermal nucleation. The activation energy was calculated and was explained with the constitution changes of the molecular chains that caused by the introduction of biphenyl moiety.展开更多
Nonisothermal melt crystallization kinetics of thio-ether-contained poly(ether ether ketone ketone) copolymers was studied by DSC. The result shows that the crystallization activation energy was increased accompanied ...Nonisothermal melt crystallization kinetics of thio-ether-contained poly(ether ether ketone ketone) copolymers was studied by DSC. The result shows that the crystallization activation energy was increased accompanied by the introduction of thio-ether structure. The random copolymer possesses a higher crystallization activation energy than the block one at the same thio-ether ratio.展开更多
基金Project (No. 011102193) supported by the Foundation of the Science and Technology Commission of Zhejiang Provincethe Foundation for Excellent Youth Teachers from the State Commission of Education, China
文摘Three yearling lambs with a rumen cannula were used to investigate the effects of supplementation with an urea-minerals lick block （ULB） on the kinetics of ruminal fibre digestion, nutrient digestibility and nitrogen （N） utilization office straw （RS）, ammonia bicarbonate （AB）-treated RS （ABRS） and hay prepared from natural pasture. The digestibility of dry matter and organic matter of RS increased by 13.1% and 12.7% （P〈0.05） when the diet was supplemented with ULB, and approached to that of ABRS, indicating that the effect of ULB on digestibility of RS is similar to that of AB treatment. The digestibility of ABRS was slightly improved by the ULB feeding. Nitrogen retention was highest in lambs fed on ABRS alone, followed by hay with ULB, and was lowest in animals fed on RS with ULB. However, both the amount and proportion of N retention to N intake were enhanced by ULB supplementation to lambs fed on hay. The proportion of N retained to N digested decreased due to ULB supplementation to lambs fed on RS or ABRS. Supplementing ULB did not greatly influence the rumen degradation of either dry matter or crude protein in each of the three diets. RS and hay had similar values in the potential extent of digestion （PED） and digestion rate of PED （kd） of fibrous materials, but the discrete lag time for RS was lower than that for hay. The AB treatment significantly increased the PED （P〈0.05） and kd （P〈0.05） of RS. Neither the PED nor kd for RS and ABRS was influenced by ULB supplementation, but the kd for hay significantly increased due to ULB. The lag time for hay was also shortened by the ULB feeding. The ULB improved the digestion of fibre in the rumen of lambs fed on low quality roughage. It is inferred that while ULB is effective in increasing nutrient digestibility of low quality roughages by improving ruminal fibre digestion. A synchronized supply of N and energy to rumen microbes should be considered to improve the efficiency of N utilization when the basal diet is ammoniated straw.
基金Project (2011CB610403) supported by the National Basic Research Program of ChinaProject (51125002) supported by the National Funds for Distinguished Young Scientists of China+2 种基金Project (51071127) supported by the National Natural Science Foundation of ChinaProjects (09-QZ-2008,24-TZ-2009) supported by the Free Research Fund of State Key Laboratory of Solidification Processing,ChinaProject (CX201008) supported by the Doctorate Foundation of Northwestern Polytechnical University,China
文摘Based on the statistical analysis of blocking effect arising from anisotropic growth,the anisotropic effect on the kinetics of solid-state transformation was investigated.The result shows that the blocking effect leads to the retardation of transformation and then a regular behavior of varying Avrami exponent.Following previous analytical model,the formulations of Avrami exponent and effective activation energy accounting for blocking effect were obtained.The anisotropic effect on the transformation depends on two factors,non-blocking factor γ and blocking scale k,which directly acts on the dimensionality of growth.The effective activation energy is not affected by the anisotropic effect.The evolution of anisotropic effect with the fraction transformed is taken into account,showing that the anisotropic effect is more severe at the middle stage of transformation.
基金sponsored by the National Natural Science Foundation of China(22178244 and 21978193)the Natural Science Foundation of Shanxi Province(202103021224039 and201901D211064)。
文摘Room-temperature sodium-sulfur(RT Na-S)batteries hold great promise for large-scale energy storage applications owing to the high energy density and earth-abundance of Na and S.However,the dissolution and migration of sodium polysulfides,uncontrollable Na dendrite growth,and the lack of studies on Na electrodeposition kinetics have hindered the development of these batteries.Herein,we reveal the mechanism of sodium polysulfides on the Na plating/stripping kinetics using a three-electrode system.First,the kinetic behavior deviates from the commonly supposed Butler-Volmer model,which is well described by the Marcus model.In addition,the specific adsorption of polysulfides on the sodium electrode surface is a key factor influencing the kinetics.Higher-order polysulfides(S_(8)^(2-)and S_(6)^(2-))exhibit distinct specific adsorption behaviors because of their high adsorption energies compared to lower-order polysulfides(S_(4)^(2-)and S_(2)^(2-)).The electrostatic effect caused by specific adsorption can accelerate the kinetics,whereas the blocking effect can slow the kinetics.Thus,this competitive relationship enables low concentrations of high-order polysulfides to stimulate kinetics.This implies that a weak shuttle effect is beneficial for obtaining a stable Na deposition in RT Na-S batteries.An in-depth understanding of the Na electrodeposition kinetics provides beneficial clues for future metal sodium/electrolyte interface designs.
文摘During winter, ice jams develop when floating ice blocks accumulate in rivers. Ice jams can dramatically decrease in the capacity of flow in a river and can cause ice flooding due to increase in water level. Submergence of floating ice blocks in front of ice cover is critical for the development of an ice jam. In this study, the effect of the rotation angle of ice blocks on the submergence of ice block was assessed. The impacts of both the drag force caused by the flow and the hydraulic pressure force on the rotation of ice block were studied. Considering both the maximum moment for anti-overturn of an ice block, and the associated rotation angle </span><i><span style="font-family:Verdana;">θ</span></i><sub><span style="font-family:Verdana;font-size:12px;">1</span></sub><span style="font-family:Verdana;">, equations for describing the criteria for ice block entrainment in front of ice cover have been derived. On the basis of the theorem for moment equilibrium, relating the moment acting on a horizontal ice block with the maximum anti-overturn moment of an ice block, the criteria for assessing the overturn-and-submergence of an ice block have been proposed. To verify results using the derived equations for calculating the critical flow velocity for ice block submergence in front of ice cover, data was collected from flume experiments in the laboratory. Experiments have been conducted using different sizes of ice block under different flow conditions in a flume which is 26.68 m long, 0.40 m wide, and 0.6 m deep. Model ice blocks were </span><span style="font-family:Verdana;">made of polypropylene </span><span style="font-family:Verdana;">and have</span><span style="font-family:Verdana;"> nearly the same as the mass density of the nat</span><span style="font-family:Verdana;">ural ice. Using proposed method for assessing ice block submergence in front of ice cover, calculated critical flow velocities agree well with those of experi</span><span style="font-family:Verdana;">ments.
文摘The nonisothermal crystallization kinetics of PEEK-PEDEK block copolymers was studied and the results showed that the Avrami exponent n of each sample was generally larger than 3, which indicates the initial crystallization of the complex. The crystallization behavior could be described as heterogeneous, multi-dimensional spherical growth with thermal nucleation. The activation energy was calculated and was explained with the constitution changes of the molecular chains that caused by the introduction of biphenyl moiety.
文摘Nonisothermal melt crystallization kinetics of thio-ether-contained poly(ether ether ketone ketone) copolymers was studied by DSC. The result shows that the crystallization activation energy was increased accompanied by the introduction of thio-ether structure. The random copolymer possesses a higher crystallization activation energy than the block one at the same thio-ether ratio.
