The changes in the contents of adenosine 5’-triphosphate (ATP) and its related breakdown compounds were investigated in the adductor muscle, mantle, gill and body trunk of oyster (Crassostrea gigas) during frozen sto...The changes in the contents of adenosine 5’-triphosphate (ATP) and its related breakdown compounds were investigated in the adductor muscle, mantle, gill and body trunk of oyster (Crassostrea gigas) during frozen storage at -20℃ and -30℃ and compared with that of the fresh oyster. The investigation was performed using an HPLC system. Different extents of ATP decomposi- tion were found in various tissues frozen at the two temperatures. The K, K’ and A.E.C values were calculated as the chemical fresh- ness indices. Considering the results of sensory evaluation, the A.E.C. value in body trunk at -20℃ and -30℃ could be used as the best freshness index for frozen oyster.展开更多
The sideward permafrost along the Qinghai-Tibet Highway (QTH) contains massive ground-ice and is at a relatively high temperature.Under the influence of the steady increase of human activities,the permafrost environme...The sideward permafrost along the Qinghai-Tibet Highway (QTH) contains massive ground-ice and is at a relatively high temperature.Under the influence of the steady increase of human activities,the permafrost environment has been changed greatly for a long time.At present,the permafrost becomes warm and rapidly degenerates,including the decline of the permafrost table,rising of the ground temperature,shortening of the length of frozen section,and extension of range of melting region.Some thaw hazards (e.g.thaw slumping and thermokarst pond) have widely occurred along both sides of the roadbed.In addition,due to the incomplete construction management,the vegetation adjacent to the highway is seriously damaged or eradicated,resulting in the land desertification and ecosystem out of balance.The dust,waste and garbage brought by drivers,passengers,maintenance workers,and transportations may also pollute the permafrost environment.展开更多
Freeze drying of an aqueous solution would result in the non-uniform distribution of solute concentration.Because ice is almost transparent to microwave, therefore such a non-uniform distribution may affect the microw...Freeze drying of an aqueous solution would result in the non-uniform distribution of solute concentration.Because ice is almost transparent to microwave, therefore such a non-uniform distribution may affect the microwave assisted freeze drying. The direct observation of the ice crystals formed under microscope reveals that the ice crystal sizes formed from de-ionized water depend on the cooling rate with fast cooling rate giving smaller ice crystals as expected. Once there is a sufficient amount of solute mixed with the de-ionized water, for example the reactive red,the size and its distribution are not very much dependent on either cooling rate or the final temperature provided there is sufficient time of cooling and the final temperature is not too low. The size of ice crystals formed within the solution of reactive red is usually below 100μm with a freezing rate of 1℃·min-1 for a droplet of the size of less than 1 mm. A simplified simulation indicates that such a small ice crystal would not cause a significant non-uniform distribution of temperature for microwave assisted freeze drying. When the ice crystal size is larger than 5 mm, heat conduction from the solute concentrated region to the ice region may need to be considered.展开更多
Using composite cubic specimens of new-old concrete,the bond splitting tensile strength and failure mechanism for the interface of new-old concrete in saturating state were explored when exposed to freeze-thaw cycling...Using composite cubic specimens of new-old concrete,the bond splitting tensile strength and failure mechanism for the interface of new-old concrete in saturating state were explored when exposed to freeze-thaw cycling. Specimens were experienced for 0,25,50,75,100 and 125 freezing cycles. The roughness and adhesion agent including cement paste,cement mortar and cement paste with 10 percent of UEA expanding agent were also investigated. The test results indicate that the bond splitting tensile strength decreases with increased numbers of freezing-and-thawing cycles. The roughness and adhesion agent have different effects on the bond strength.展开更多
This paper focused on the sessile droplet freezing and ice adhesion on aluminum with different wettability （hydrophilic, com- mon hydrophobic, and superhydrophobic surfaces, coded as HIS, CHS, SHS, respectively） ove...This paper focused on the sessile droplet freezing and ice adhesion on aluminum with different wettability （hydrophilic, com- mon hydrophobic, and superhydrophobic surfaces, coded as HIS, CHS, SHS, respectively） over a surface temperature range of -9℃ to -19℃. It was found that SHS could retard the sessile droplet freezing and lower the ice adhesion probably due to the interfacial air pockets （IAPs） on water/SHS interface. However, as surface temperature decreasing, some IAPs were squeezed out and such freezing retarding and adhesion lowering effect for SHS was reduced greatly. For a surface temperature of-19℃, ice adhesion on SHS was even greater than that on CHS. To discover the reason for the squeezing out of lAPs, forces applied to the suspended water on IAPs were analyzed and it was found that the stability of IAPs was associated with surface mi- cro-structures and surface temperature. These findings might be helpful to designing of SHS with good anti-icing properties.展开更多
文摘The changes in the contents of adenosine 5’-triphosphate (ATP) and its related breakdown compounds were investigated in the adductor muscle, mantle, gill and body trunk of oyster (Crassostrea gigas) during frozen storage at -20℃ and -30℃ and compared with that of the fresh oyster. The investigation was performed using an HPLC system. Different extents of ATP decomposi- tion were found in various tissues frozen at the two temperatures. The K, K’ and A.E.C values were calculated as the chemical fresh- ness indices. Considering the results of sensory evaluation, the A.E.C. value in body trunk at -20℃ and -30℃ could be used as the best freshness index for frozen oyster.
基金Project(KZCX2-YW-Q03-04) supported by the Important Orientation Projects of the Chinese Academy of SciencesProject(41030741) supported by the National Natural Science of ChinaProject(2010CB434813) supported by the National Basic Research Program of China
文摘The sideward permafrost along the Qinghai-Tibet Highway (QTH) contains massive ground-ice and is at a relatively high temperature.Under the influence of the steady increase of human activities,the permafrost environment has been changed greatly for a long time.At present,the permafrost becomes warm and rapidly degenerates,including the decline of the permafrost table,rising of the ground temperature,shortening of the length of frozen section,and extension of range of melting region.Some thaw hazards (e.g.thaw slumping and thermokarst pond) have widely occurred along both sides of the roadbed.In addition,due to the incomplete construction management,the vegetation adjacent to the highway is seriously damaged or eradicated,resulting in the land desertification and ecosystem out of balance.The dust,waste and garbage brought by drivers,passengers,maintenance workers,and transportations may also pollute the permafrost environment.
文摘Freeze drying of an aqueous solution would result in the non-uniform distribution of solute concentration.Because ice is almost transparent to microwave, therefore such a non-uniform distribution may affect the microwave assisted freeze drying. The direct observation of the ice crystals formed under microscope reveals that the ice crystal sizes formed from de-ionized water depend on the cooling rate with fast cooling rate giving smaller ice crystals as expected. Once there is a sufficient amount of solute mixed with the de-ionized water, for example the reactive red,the size and its distribution are not very much dependent on either cooling rate or the final temperature provided there is sufficient time of cooling and the final temperature is not too low. The size of ice crystals formed within the solution of reactive red is usually below 100μm with a freezing rate of 1℃·min-1 for a droplet of the size of less than 1 mm. A simplified simulation indicates that such a small ice crystal would not cause a significant non-uniform distribution of temperature for microwave assisted freeze drying. When the ice crystal size is larger than 5 mm, heat conduction from the solute concentrated region to the ice region may need to be considered.
基金the National Natural Science Foundation of China(Grant No.59778045).
文摘Using composite cubic specimens of new-old concrete,the bond splitting tensile strength and failure mechanism for the interface of new-old concrete in saturating state were explored when exposed to freeze-thaw cycling. Specimens were experienced for 0,25,50,75,100 and 125 freezing cycles. The roughness and adhesion agent including cement paste,cement mortar and cement paste with 10 percent of UEA expanding agent were also investigated. The test results indicate that the bond splitting tensile strength decreases with increased numbers of freezing-and-thawing cycles. The roughness and adhesion agent have different effects on the bond strength.
基金supported by the National Natural Science Foundation of China(Grant Nos.21203089 and 51263018)International Science and Technology Cooperation Program of China(Grant No.2012DFA51200)+1 种基金Science and Technology Project of Jiangxi Province(Grant No.20123BDH80015)the Open Fund of Jiangsu Key Laboratory for Biomass-based Energy and Enzyme Technology(Grant No.JSBEET1224)
文摘This paper focused on the sessile droplet freezing and ice adhesion on aluminum with different wettability （hydrophilic, com- mon hydrophobic, and superhydrophobic surfaces, coded as HIS, CHS, SHS, respectively） over a surface temperature range of -9℃ to -19℃. It was found that SHS could retard the sessile droplet freezing and lower the ice adhesion probably due to the interfacial air pockets （IAPs） on water/SHS interface. However, as surface temperature decreasing, some IAPs were squeezed out and such freezing retarding and adhesion lowering effect for SHS was reduced greatly. For a surface temperature of-19℃, ice adhesion on SHS was even greater than that on CHS. To discover the reason for the squeezing out of lAPs, forces applied to the suspended water on IAPs were analyzed and it was found that the stability of IAPs was associated with surface mi- cro-structures and surface temperature. These findings might be helpful to designing of SHS with good anti-icing properties.
