Under the environment of an artificial climate chamber, supercooling point （SCP） and freezing point （FP） in flower and young fruit at different development stages and freezing injuries of floral organs were studie...Under the environment of an artificial climate chamber, supercooling point （SCP） and freezing point （FP） in flower and young fruit at different development stages and freezing injuries of floral organs were studied. The apricot cultivars tested were Kety, Golden Sun and Honghebao. With the development of flower buds, SCP and FP increased, which indicated that their cold resistance decreased. SCP and FP varied with different floral organs. For different apricot cultivars, it was found that, the lower SCP or FP in floral organs was, the more resistant capacity the cultivar had, and the larger the temperature interval from SCP to FP was. SCP was not a constant value, but a range. Frequency distribution of SCP in petals was more dispersing than that in stamens and pistils. Floral organs could maintain a supercooling state to avoid ice formation, but they were sensitive to freezing. Once floral organs froze, thev turned brown after thawing.展开更多
Supercooling of the microencapsulated phase change materials（PCMs） during cooling usually happens. This phenomenon can interfere with heat transfer and is necessary to further overcome. In this study, mela- mine-for...Supercooling of the microencapsulated phase change materials（PCMs） during cooling usually happens. This phenomenon can interfere with heat transfer and is necessary to further overcome. In this study, mela- mine-formaldehyde microcapsules containing two n-alkane PCMs, namely, n-dodecane（Cl2） or n-tetradecane（C14） were prepared by in situ polymerization. A small amount of n-hexatriacontane（C36） was introduced as an organic ge- lator into the core of microcapsules to cope with the supercooling problem. Analyses demonstrate that supercooling of the microencapsulated C12 or C14 was significantly suppressed by adding 3%（mass fraction） C36, without changing the spherical morphology and dispersibility. It could be also found that the enthalpy of microencapsulated CI2 or C14 containing C36 was similar to that of microencapsulated n-alkanes without C36, whereas the difference between onsets of crystallization and melting（degree of supercooling） is similar to that of those of pure n-alkanes, suggesting the re- markable suppression ability of the organic gelator on supercooling.展开更多
This study aims to develop a paraffin-based phase change material(PCM) emulsion with a low extent of supercooling for thermal energy storage(TES) systems to improve the cooling efficiency.Hexadecane-water emulsions we...This study aims to develop a paraffin-based phase change material(PCM) emulsion with a low extent of supercooling for thermal energy storage(TES) systems to improve the cooling efficiency.Hexadecane-water emulsions were prepared and characterized. Multi-wall carbon nanotubes(MWCNTs) were dispersed in the emulsion as a nucleating agent to reduce the supercooling. The MWCNTs were chemically modified with carboxyl groups to improve the dispersion of the tubular particles in the organic liquid. Thermal analyses of the emulsions by differential scanning calorimeter(DSC) indicated that the extent of supercooling was significantly reduced. The concentration of the nucleating agent for an effective supercooling suppression as found to be very low, in agreement with previous findings, and there appeared to be a minimum concentration for the supercooling reduction.展开更多
Comparing the solidification characteristics of supercooling directional solidification(SDS) with constrained directional solidification(D. S. ) and considering the inheritance of supercooled melt, the supercooling di...Comparing the solidification characteristics of supercooling directional solidification(SDS) with constrained directional solidification(D. S. ) and considering the inheritance of supercooled melt, the supercooling directional solidification technique with the combination of melt supercooing and traditional directional solidification was proposed. An exploring study on SDS techniques was also conducted by using appropriate selfmade facilities and the deep supercooling of Cu-5. O % Ni alloy and its directional solidification were implemented. The experimental results show that: 1 ) the solidification microstructure produced by SDS are nearly the same as that by LMC technique, its primary arm spacing is around 30 Um in average and the secondary sidebranch is considerably degenerated; 2) the primary arm trunk of microstructure appears straight and fine, and the average deviation of crystal growth orientation from the axial line is about 5. 8; 3) a mathematical model describing the relationship between melt supercooling by SDS and the solidification rate, namely T-T model,was established, by which the microstructure evolution in SDS can be explained.展开更多
Microencapsulation of phase change materials(MPCM)is an effective way to achieve solar energy management.However,the crystallization of phase change materials(PCMs)in microcapsules will produce supercooling,which will...Microencapsulation of phase change materials(MPCM)is an effective way to achieve solar energy management.However,the crystallization of phase change materials(PCMs)in microcapsules will produce supercooling,which will affect the energy storage efficiency of MPCM.The incorporation of TiO_(2)nanoparticles into MPCM can alleviate supercooling.In this work,octadecyltrimethoxysilane(ODTMS)was used to modify the solid nucleating agent TiO_(2)(m-TiO_(2))to improve its compatibility with n-Octadecane.Then,MPCM based on m-TiO_(2)nucleating agent,melamine-formaldehyde resin(MF)shell material,and n-Octadecane core material was prepared.Differential scanning calorimetry(DSC)results demonstrate that the supercooling degree(ΔT)of MPCM(MPCM-02)decreases to 0℃with a tiny level of 0.25 wt%m-TiO_(2),while the MPCM with unmodified TiO_(2)is 6.1℃and the MPCM without nucleating agent is 4.1℃.Besides,the phase change enthalpy(ΔHm)and encapsulation efficiency(E)of MPCM-02 remain at 183.7 J/g and 95.3%,respectively.Finally,phase change composite materials with photothermal conversion capabilities were constructed by MXenes,MPCM,and polyurethane acrylate(PUA).When 1 wt%MXenes and 30 wt%MPCM were incorporated into PUA matrix,the thermal conductivity and surface temperature after 1200s of infrared light irradiation were 48.8%and 8.2℃higher than pure PUA matrix.These results demonstrate the good solar energy storage capabilities of the MPCM,which possesses promising application potential in the field of solar energy thermal management and human thermal regulation.展开更多
The objective of this paper is to investigate water supercooling. Supercooling occurs when a liquid does not freeze although its temperature is below its freezing point. In general, supercooling is an unstable conditi...The objective of this paper is to investigate water supercooling. Supercooling occurs when a liquid does not freeze although its temperature is below its freezing point. In general, supercooling is an unstable condition and occurs under special conditions. The parameters that influence supercooling stability and probability of occurrence include freezer temperature and water’s initial temperature. In this paper, it is shown that with a freezer temperature range of -3℃ to -8℃, supercooling is most likely to happen and is independent of the water’s initial temperature. Furthermore, as the freezer temperature decreases, the probability of nucleation increases, causing instant freezing. Finally, it is concluded that the Mpemba effect, in which initially hot water freezes faster than initially cold water, is due to the supercooling instability in initially hot water in which nucleation agents are more active.展开更多
We supercooled fresh-cut onion at−5℃ for 12 h.After supercooling,the electric impedance properties of the samples were evaluated by electrical impedance spectroscopy over the frequency range of 42 Hz−5 MHz.The time-t...We supercooled fresh-cut onion at−5℃ for 12 h.After supercooling,the electric impedance properties of the samples were evaluated by electrical impedance spectroscopy over the frequency range of 42 Hz−5 MHz.The time-temperature profiles of samples indicated that the freezing point and supercooling point were−2.3℃±0.7℃ and−6.9℃±1.0℃,respectively.The results indicated that 34 of the 36 supercooled samples exhibited a definite circular arc in the Cole-Cole plot,which suggested that the cell membrane remained intact during supercooling.In the other two samples which did not exhibit a definite circular arc,the cell membrane had sustained serious damage during supercooling.Furthermore,there was large difference in drip loss percentage between supercooled samples exhibited a definite circular arc in the Cole-Cole plot and samples not exhibiting a definite circular arc.Our results suggest that fresh-cut onions can be supercooled at−5℃.展开更多
Supercooling storage reduces the temperature of a product by lowering its freezing point without phase transition and may extend its shelf life.However,it is difficult to maintain the supercooled state of food as it i...Supercooling storage reduces the temperature of a product by lowering its freezing point without phase transition and may extend its shelf life.However,it is difficult to maintain the supercooled state of food as it is thermodynamically metastable.A slow cooling rate and minimal fluctuation are essential for achieving stable supercooling storage.Therefore,a stepwise algorithm was adopted for supercooling storage in this study.Salmon and olive flounder were stored at 3℃(refrigeration),18℃(freezing),and2℃(supercooling)for 12 days.Samples were maintained in a supercooled state and unfrozen during the storage period.Samples stored after the supercooling treatment were superior with respect to drip loss and water holding capacity(WHC)compared to frozen samples,regardless of the type of sample.WHC and total volatile basic nitrogen values of olive flounder was higher than those in salmon owing to the higher water and protein content in olive flounder than in salmon.Moreover,the supercooled samples inhibited the increase in trimethylamine and volatile basic nitrogen levels.Microbial growth was slow.Thus,a stepwise algorithm for stable supercooled storage was achieved,which effectively preserved fish quality better than freezing and refrigeration storage.展开更多
Supercooling is recognized as a novel preservation method because it maintains the freshness of food without tissue damage caused by ice crystals.Food is a complicated matrix composed of several components with varyin...Supercooling is recognized as a novel preservation method because it maintains the freshness of food without tissue damage caused by ice crystals.Food is a complicated matrix composed of several components with varying freezing points depending on the food type.In this study,effects of food compositions on stability of supercooling preservation were investigated using a model food to define the interaction between supercooling maintenance and the factor of food composition.Furthermore,chicken meat(leg and wing)was used to confirm food freshness during extended storage.The higher the fat and salt content of the model food,better was the maintenance of the supercooled state;however,higher the moisture content,worse was the maintenance of supercooled state.The presence of the fat layer affected the supercooling maintenance rate.In experiments with real food,the chicken leg and wing samples were 80%and 90%supercooled,respectively.The samples conserved at superooling presented significantly lower drip loss,total volatile basic nitrogen,and total aerobic count than those of the refrigeration.In addition,water holding capacity of supercooled samples were not significant differences compared to frozen samples.展开更多
1 Introduction Since differential thermal analysis(DTA) was used to detect a specific exothermic event associated with cold injury, organic supercooling has been reported in over 240 species of 33 angiospermous famili...1 Introduction Since differential thermal analysis(DTA) was used to detect a specific exothermic event associated with cold injury, organic supercooling has been reported in over 240 species of 33 angiospermous families and one gymnospermous family. Several hypotheses about the mechanism of the supercooling of flower buds have been proposed, e.g. lower water potential, tissue compactness, ice nucleation factors and the tissue barrier against展开更多
It is the first time for MRI to be used in the research of flower buds supercooling. Directobservation on freezing course of living flower buds of Camellia yuhsienensis by MRI and tissue browning test showed that free...It is the first time for MRI to be used in the research of flower buds supercooling. Directobservation on freezing course of living flower buds of Camellia yuhsienensis by MRI and tissue browning test showed that freezing order of the flower organs is bud axis, scale, petal, pistil and stamen. It is coincident with the direction of ice development from bud axes to flower organs upwards. The corresponding results from MRI and freezing-fixation showed that the water translocation from flower organs to axes and scales is carried on in the course of bud freezing. ’H spectral measurement of NMR was used to follow the decrease of unfrozen water in the buds during the cooling.展开更多
Climatic warming has advanced the spring phenology of plants and disrupted the alignment of phenology with weather patterns.Such misalignments can cause problems as extreme weather events become more frequent and thus...Climatic warming has advanced the spring phenology of plants and disrupted the alignment of phenology with weather patterns.Such misalignments can cause problems as extreme weather events become more frequent and thus impact the survival,growth and reproduction of plants.To prevent freezing within their cells during the growing season,plants adopt a supercooling strategy.However,the weather event severity and seasonal timing may impact the plant’s recovery after a freezing event.We conducted experiments to investigate how extreme freezing events of four different severities impacted the supercooling points and senescence of two dominant alpine plant species,Potentilla saundersiana(mid-summer fowering)and Gentiana parvula(latesummer fowering)on the Qinghai-Tibet Plateau(QTP).We also explored how the phenological stage impacted P.saundersiana’s response to freezing events.We found that both species exhibited supercooling upon exposed to frost damage.However,the average supercooling point for P.saundersiana was−6.9℃and was infuenced by minimum temperature,duration and phenological stage.Whereas,the average supercooling point for G.parvula was−4.8℃,and neither minimum temperature nor duration had an effect on the supercooling point.In addition,the minimum temperature treatment of−10℃caused death in both plants when held constant for 4 h.Our study provides the frst experimental dataset exploring the supercooling points of alpine plants on the QTP.Given the increasing probability of alpine plants encounters frost events,these results are of great signifcance for understanding the growth and survival strategies of alpine plants to cope with the adverse effects of extreme climate.展开更多
Global warming leads to snow cover loss in the alpine ecosystem,exposing seeds to extreme diurnal temperature fluctuations during the growing season.The risk of freezing increases as seeds have increased moisture cont...Global warming leads to snow cover loss in the alpine ecosystem,exposing seeds to extreme diurnal temperature fluctuations during the growing season.The risk of freezing increases as seeds have increased moisture content.Studying the survival mechanisms of seeds at low temperatures can help analyze changes in alpine meadow populations and target conservation efforts.Here,we used three species of Poaceae as a model to understand freezing stress.Fully imbibed Elymus dahuricus,Festuca elata,and Lolium multiflorum seeds were subjected to programmed cooling at fast and slow rates(-1.0/0.05℃/min)and then assessed for survival.Differential Scanning Calorimetry was used to analyze thermal transitions during cooling.HE-stained paraffin sections and a Transmission Electron Microscope were employed to observe internal morphology and ultrastructural changes.E.dahuricus seeds exhibited greater tolerance to low temperatures than those of the other two species,with an LT_(50)of approximately-20℃for both cooling rates and maintained relatively intact ultrastructure.The observed the low-temperature exotherm(LTE)correlated with seed survival,with viability decreasing extensively below LTE.Fast cooling caused fewer changes to seed morphology and ultrastructure than slow cooling,suggesting that the primary survival mechanism during fast cooling is freezing avoidance through supercooling.Seeds exhibited greater freeze tolerance under slow than fast cooling,primarily by migrating intracellular water to extracellular spaces where it froze,causing considerable damage to cell ultrastructure and forming apparent cavities in some seeds.展开更多
A water-TiO2nanofluid with a weight fraction of 5% and an average particle size of 75 nm is used to investigate the effect of TiO2 nanoparticles on the crystallization and melting behaviors of deionized water by using...A water-TiO2nanofluid with a weight fraction of 5% and an average particle size of 75 nm is used to investigate the effect of TiO2 nanoparticles on the crystallization and melting behaviors of deionized water by using differential scanning calorimetry（DSC）at four different cooling rates,3,5,7,9 ℃/min.The DSC experimental results show that the water-TiO2 nanofluid has a lower supercooling degree and a faster crystallization rate than the deionized water.With the increase in the cooling rate,the influence of the TiO2 nanoparticles on the supercooling degree of the deionized water becomes greater,but on the crystallization rate it turns lower.During the melting process,compared with the deionized water,the water-TiO2 nanofluid has a lower melting temperature,a less latent heat and a higher melting rate.展开更多
The formation and evolution characteristics of bcc phase during the isothermal relaxation processes for supercooled-liquid and amorphous Pb were investigated by molecular dynamics simulation and cluster-type index met...The formation and evolution characteristics of bcc phase during the isothermal relaxation processes for supercooled-liquid and amorphous Pb were investigated by molecular dynamics simulation and cluster-type index method （CTIM）. It is found that during the relaxation process, the formation and evolution of bcc phase are closely dependent on the initial temperature and structure. During the simulation time scale, when the initial temperature is in the range of supercooled liquid region, the bcc phase can be formed and kept a long time; while it is in the range of glassy region, the bcc phase can be formed at first and then partially transformed into hcp phase; when it decreases to the lower one, the hcp and fcc phases can be directly transformed from the glassy structure without undergoing the metastable bcc phase. The Ostwald＇s ＂step rule＂ is impactful during the isothermal relaxation process of the supercooled and glassy Pb, and the metastable bcc phase plays an important role in the precursor of crystallization.展开更多
Equations(2)and(6)and the corresponding discussion in the paper[Chin.Phys.Lett.42,056301(2025)]have been corrected.These modiffcations do not affect the results derived in the paper.
High-speed trains operating in freezing rain are highly susceptible to severe ice accretion in the pantograph region,which compromises both power transmission efficiency and dynamic performance.To elucidate the underl...High-speed trains operating in freezing rain are highly susceptible to severe ice accretion in the pantograph region,which compromises both power transmission efficiency and dynamic performance.To elucidate the underlying mechanisms of this phenomenon,an Euler-Euler multiphase flow model was employed to simulate droplet impingement and collection on the pantograph surface,while a glaze-ice formation model incorporating wall film dynamics was used to capture the subsequent growth of ice.The effects of key parameters—including liquid water content,ambient temperature,train velocity,and droplet diameter—on the amount and morphology of ice were systematically investigated.The results show that ice accumulation intensifies with increasing liquid water content decreasing ambient temperature,and rising train speed.In contrast,larger droplet diameters reduce the overall ice mass but promote localized accretion on major structural elements.This behavior arises because larger droplets,with greater inertia,are less susceptible to entrainment by airflow into the pantograph's base region.During extended operation,substantial ice buildup develops on the pantograph head and upper and lower arms,severely impairing current collection from the overhead line and hindering the pantograph's lifting and lowering motions.展开更多
The icing characteristics of supercooled large droplet(SLD)impacting carbon fiber-reinforced composites(CFRCs)remain poorly understood,hindering the enhancement of ice protection capabilities and the certification of ...The icing characteristics of supercooled large droplet(SLD)impacting carbon fiber-reinforced composites(CFRCs)remain poorly understood,hindering the enhancement of ice protection capabilities and the certification of ice-accreted composite aircraft.The paper systematically investigates the effects of the supercooling degree,the surface temperature,and the impact velocity on the ice accretion behavior of SLDs impacting carbon fiber-reinforced epoxy composite surfaces.To address the ice-prone nature of CFRCs,nanoparticle-modified anti-icing coatings are developed,and the icing characteristics of SLD-impacted modified carbon fiber-reinforced epoxy composite surfaces are analyzed.Results demonstrate that surface-modified carbon fiber-reinforced epoxy composite exhibits significantly delayed ice formation.Under conditions of droplet temperature(−15℃)and surface temperature(−18℃),the icing time of hydrophobic-modified CFRCs was delayed by over 1100 ms,representing a 5.4-fold improvement compared to the unmodified carbon fiber-reinforced epoxy composite.展开更多
文摘Under the environment of an artificial climate chamber, supercooling point （SCP） and freezing point （FP） in flower and young fruit at different development stages and freezing injuries of floral organs were studied. The apricot cultivars tested were Kety, Golden Sun and Honghebao. With the development of flower buds, SCP and FP increased, which indicated that their cold resistance decreased. SCP and FP varied with different floral organs. For different apricot cultivars, it was found that, the lower SCP or FP in floral organs was, the more resistant capacity the cultivar had, and the larger the temperature interval from SCP to FP was. SCP was not a constant value, but a range. Frequency distribution of SCP in petals was more dispersing than that in stamens and pistils. Floral organs could maintain a supercooling state to avoid ice formation, but they were sensitive to freezing. Once floral organs froze, thev turned brown after thawing.
文摘Supercooling of the microencapsulated phase change materials（PCMs） during cooling usually happens. This phenomenon can interfere with heat transfer and is necessary to further overcome. In this study, mela- mine-formaldehyde microcapsules containing two n-alkane PCMs, namely, n-dodecane（Cl2） or n-tetradecane（C14） were prepared by in situ polymerization. A small amount of n-hexatriacontane（C36） was introduced as an organic ge- lator into the core of microcapsules to cope with the supercooling problem. Analyses demonstrate that supercooling of the microencapsulated C12 or C14 was significantly suppressed by adding 3%（mass fraction） C36, without changing the spherical morphology and dispersibility. It could be also found that the enthalpy of microencapsulated CI2 or C14 containing C36 was similar to that of microencapsulated n-alkanes without C36, whereas the difference between onsets of crystallization and melting（degree of supercooling） is similar to that of those of pure n-alkanes, suggesting the re- markable suppression ability of the organic gelator on supercooling.
基金Supported by the Research Grant Council of the Hong Kong SAR government(GRF PolyU 5241/11E)
文摘This study aims to develop a paraffin-based phase change material(PCM) emulsion with a low extent of supercooling for thermal energy storage(TES) systems to improve the cooling efficiency.Hexadecane-water emulsions were prepared and characterized. Multi-wall carbon nanotubes(MWCNTs) were dispersed in the emulsion as a nucleating agent to reduce the supercooling. The MWCNTs were chemically modified with carboxyl groups to improve the dispersion of the tubular particles in the organic liquid. Thermal analyses of the emulsions by differential scanning calorimeter(DSC) indicated that the extent of supercooling was significantly reduced. The concentration of the nucleating agent for an effective supercooling suppression as found to be very low, in agreement with previous findings, and there appeared to be a minimum concentration for the supercooling reduction.
文摘Comparing the solidification characteristics of supercooling directional solidification(SDS) with constrained directional solidification(D. S. ) and considering the inheritance of supercooled melt, the supercooling directional solidification technique with the combination of melt supercooing and traditional directional solidification was proposed. An exploring study on SDS techniques was also conducted by using appropriate selfmade facilities and the deep supercooling of Cu-5. O % Ni alloy and its directional solidification were implemented. The experimental results show that: 1 ) the solidification microstructure produced by SDS are nearly the same as that by LMC technique, its primary arm spacing is around 30 Um in average and the secondary sidebranch is considerably degenerated; 2) the primary arm trunk of microstructure appears straight and fine, and the average deviation of crystal growth orientation from the axial line is about 5. 8; 3) a mathematical model describing the relationship between melt supercooling by SDS and the solidification rate, namely T-T model,was established, by which the microstructure evolution in SDS can be explained.
基金supported by the National Natural Science Foundation of China(No.U20A20299)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011985)the support from the Scientific and Technological Innovation Strategy Program of Guangdong Province:Guangdong-Hong Kong-Macao Technology Cooperation Funding Scheme(No.2022A0505030026).
文摘Microencapsulation of phase change materials(MPCM)is an effective way to achieve solar energy management.However,the crystallization of phase change materials(PCMs)in microcapsules will produce supercooling,which will affect the energy storage efficiency of MPCM.The incorporation of TiO_(2)nanoparticles into MPCM can alleviate supercooling.In this work,octadecyltrimethoxysilane(ODTMS)was used to modify the solid nucleating agent TiO_(2)(m-TiO_(2))to improve its compatibility with n-Octadecane.Then,MPCM based on m-TiO_(2)nucleating agent,melamine-formaldehyde resin(MF)shell material,and n-Octadecane core material was prepared.Differential scanning calorimetry(DSC)results demonstrate that the supercooling degree(ΔT)of MPCM(MPCM-02)decreases to 0℃with a tiny level of 0.25 wt%m-TiO_(2),while the MPCM with unmodified TiO_(2)is 6.1℃and the MPCM without nucleating agent is 4.1℃.Besides,the phase change enthalpy(ΔHm)and encapsulation efficiency(E)of MPCM-02 remain at 183.7 J/g and 95.3%,respectively.Finally,phase change composite materials with photothermal conversion capabilities were constructed by MXenes,MPCM,and polyurethane acrylate(PUA).When 1 wt%MXenes and 30 wt%MPCM were incorporated into PUA matrix,the thermal conductivity and surface temperature after 1200s of infrared light irradiation were 48.8%and 8.2℃higher than pure PUA matrix.These results demonstrate the good solar energy storage capabilities of the MPCM,which possesses promising application potential in the field of solar energy thermal management and human thermal regulation.
文摘The objective of this paper is to investigate water supercooling. Supercooling occurs when a liquid does not freeze although its temperature is below its freezing point. In general, supercooling is an unstable condition and occurs under special conditions. The parameters that influence supercooling stability and probability of occurrence include freezer temperature and water’s initial temperature. In this paper, it is shown that with a freezer temperature range of -3℃ to -8℃, supercooling is most likely to happen and is independent of the water’s initial temperature. Furthermore, as the freezer temperature decreases, the probability of nucleation increases, causing instant freezing. Finally, it is concluded that the Mpemba effect, in which initially hot water freezes faster than initially cold water, is due to the supercooling instability in initially hot water in which nucleation agents are more active.
基金This work was supported by JSPS KAKENHI,grant number JP16H05001[Grant-in-Aid for Scientific Research(B)]JP16K15010[Grant-in-Aid for Exploratory Research].
文摘We supercooled fresh-cut onion at−5℃ for 12 h.After supercooling,the electric impedance properties of the samples were evaluated by electrical impedance spectroscopy over the frequency range of 42 Hz−5 MHz.The time-temperature profiles of samples indicated that the freezing point and supercooling point were−2.3℃±0.7℃ and−6.9℃±1.0℃,respectively.The results indicated that 34 of the 36 supercooled samples exhibited a definite circular arc in the Cole-Cole plot,which suggested that the cell membrane remained intact during supercooling.In the other two samples which did not exhibit a definite circular arc,the cell membrane had sustained serious damage during supercooling.Furthermore,there was large difference in drip loss percentage between supercooled samples exhibited a definite circular arc in the Cole-Cole plot and samples not exhibiting a definite circular arc.Our results suggest that fresh-cut onions can be supercooled at−5℃.
文摘Supercooling storage reduces the temperature of a product by lowering its freezing point without phase transition and may extend its shelf life.However,it is difficult to maintain the supercooled state of food as it is thermodynamically metastable.A slow cooling rate and minimal fluctuation are essential for achieving stable supercooling storage.Therefore,a stepwise algorithm was adopted for supercooling storage in this study.Salmon and olive flounder were stored at 3℃(refrigeration),18℃(freezing),and2℃(supercooling)for 12 days.Samples were maintained in a supercooled state and unfrozen during the storage period.Samples stored after the supercooling treatment were superior with respect to drip loss and water holding capacity(WHC)compared to frozen samples,regardless of the type of sample.WHC and total volatile basic nitrogen values of olive flounder was higher than those in salmon owing to the higher water and protein content in olive flounder than in salmon.Moreover,the supercooled samples inhibited the increase in trimethylamine and volatile basic nitrogen levels.Microbial growth was slow.Thus,a stepwise algorithm for stable supercooled storage was achieved,which effectively preserved fish quality better than freezing and refrigeration storage.
文摘Supercooling is recognized as a novel preservation method because it maintains the freshness of food without tissue damage caused by ice crystals.Food is a complicated matrix composed of several components with varying freezing points depending on the food type.In this study,effects of food compositions on stability of supercooling preservation were investigated using a model food to define the interaction between supercooling maintenance and the factor of food composition.Furthermore,chicken meat(leg and wing)was used to confirm food freshness during extended storage.The higher the fat and salt content of the model food,better was the maintenance of the supercooled state;however,higher the moisture content,worse was the maintenance of supercooled state.The presence of the fat layer affected the supercooling maintenance rate.In experiments with real food,the chicken leg and wing samples were 80%and 90%supercooled,respectively.The samples conserved at superooling presented significantly lower drip loss,total volatile basic nitrogen,and total aerobic count than those of the refrigeration.In addition,water holding capacity of supercooled samples were not significant differences compared to frozen samples.
文摘1 Introduction Since differential thermal analysis(DTA) was used to detect a specific exothermic event associated with cold injury, organic supercooling has been reported in over 240 species of 33 angiospermous families and one gymnospermous family. Several hypotheses about the mechanism of the supercooling of flower buds have been proposed, e.g. lower water potential, tissue compactness, ice nucleation factors and the tissue barrier against
基金Project supported by the National Natural Science Foundaion of China.
文摘It is the first time for MRI to be used in the research of flower buds supercooling. Directobservation on freezing course of living flower buds of Camellia yuhsienensis by MRI and tissue browning test showed that freezing order of the flower organs is bud axis, scale, petal, pistil and stamen. It is coincident with the direction of ice development from bud axes to flower organs upwards. The corresponding results from MRI and freezing-fixation showed that the water translocation from flower organs to axes and scales is carried on in the course of bud freezing. ’H spectral measurement of NMR was used to follow the decrease of unfrozen water in the buds during the cooling.
基金the National Natural Science Foundation of China(42230504,31800407 and 32160285)Qinghai Province Science and Technology Department(2020-ZJ-952Q)the Second Comprehensive scientifc expedition on the Tibetan Plateau(2019QZKK0302)supported this work.
文摘Climatic warming has advanced the spring phenology of plants and disrupted the alignment of phenology with weather patterns.Such misalignments can cause problems as extreme weather events become more frequent and thus impact the survival,growth and reproduction of plants.To prevent freezing within their cells during the growing season,plants adopt a supercooling strategy.However,the weather event severity and seasonal timing may impact the plant’s recovery after a freezing event.We conducted experiments to investigate how extreme freezing events of four different severities impacted the supercooling points and senescence of two dominant alpine plant species,Potentilla saundersiana(mid-summer fowering)and Gentiana parvula(latesummer fowering)on the Qinghai-Tibet Plateau(QTP).We also explored how the phenological stage impacted P.saundersiana’s response to freezing events.We found that both species exhibited supercooling upon exposed to frost damage.However,the average supercooling point for P.saundersiana was−6.9℃and was infuenced by minimum temperature,duration and phenological stage.Whereas,the average supercooling point for G.parvula was−4.8℃,and neither minimum temperature nor duration had an effect on the supercooling point.In addition,the minimum temperature treatment of−10℃caused death in both plants when held constant for 4 h.Our study provides the frst experimental dataset exploring the supercooling points of alpine plants on the QTP.Given the increasing probability of alpine plants encounters frost events,these results are of great signifcance for understanding the growth and survival strategies of alpine plants to cope with the adverse effects of extreme climate.
基金supported by National Science Foundation of China(NSFC)[No.32001119].
文摘Global warming leads to snow cover loss in the alpine ecosystem,exposing seeds to extreme diurnal temperature fluctuations during the growing season.The risk of freezing increases as seeds have increased moisture content.Studying the survival mechanisms of seeds at low temperatures can help analyze changes in alpine meadow populations and target conservation efforts.Here,we used three species of Poaceae as a model to understand freezing stress.Fully imbibed Elymus dahuricus,Festuca elata,and Lolium multiflorum seeds were subjected to programmed cooling at fast and slow rates(-1.0/0.05℃/min)and then assessed for survival.Differential Scanning Calorimetry was used to analyze thermal transitions during cooling.HE-stained paraffin sections and a Transmission Electron Microscope were employed to observe internal morphology and ultrastructural changes.E.dahuricus seeds exhibited greater tolerance to low temperatures than those of the other two species,with an LT_(50)of approximately-20℃for both cooling rates and maintained relatively intact ultrastructure.The observed the low-temperature exotherm(LTE)correlated with seed survival,with viability decreasing extensively below LTE.Fast cooling caused fewer changes to seed morphology and ultrastructure than slow cooling,suggesting that the primary survival mechanism during fast cooling is freezing avoidance through supercooling.Seeds exhibited greater freeze tolerance under slow than fast cooling,primarily by migrating intracellular water to extracellular spaces where it froze,causing considerable damage to cell ultrastructure and forming apparent cavities in some seeds.
基金The National Natural Science Foundation of China(No.50876022)
文摘A water-TiO2nanofluid with a weight fraction of 5% and an average particle size of 75 nm is used to investigate the effect of TiO2 nanoparticles on the crystallization and melting behaviors of deionized water by using differential scanning calorimetry（DSC）at four different cooling rates,3,5,7,9 ℃/min.The DSC experimental results show that the water-TiO2 nanofluid has a lower supercooling degree and a faster crystallization rate than the deionized water.With the increase in the cooling rate,the influence of the TiO2 nanoparticles on the supercooling degree of the deionized water becomes greater,but on the crystallization rate it turns lower.During the melting process,compared with the deionized water,the water-TiO2 nanofluid has a lower melting temperature,a less latent heat and a higher melting rate.
基金Projects (50831003, 50571037) supported by the National Natural Science Foundation of China
文摘The formation and evolution characteristics of bcc phase during the isothermal relaxation processes for supercooled-liquid and amorphous Pb were investigated by molecular dynamics simulation and cluster-type index method （CTIM）. It is found that during the relaxation process, the formation and evolution of bcc phase are closely dependent on the initial temperature and structure. During the simulation time scale, when the initial temperature is in the range of supercooled liquid region, the bcc phase can be formed and kept a long time; while it is in the range of glassy region, the bcc phase can be formed at first and then partially transformed into hcp phase; when it decreases to the lower one, the hcp and fcc phases can be directly transformed from the glassy structure without undergoing the metastable bcc phase. The Ostwald＇s ＂step rule＂ is impactful during the isothermal relaxation process of the supercooled and glassy Pb, and the metastable bcc phase plays an important role in the precursor of crystallization.
文摘Equations(2)and(6)and the corresponding discussion in the paper[Chin.Phys.Lett.42,056301(2025)]have been corrected.These modiffcations do not affect the results derived in the paper.
基金Natural Science Foundation of Shandong Province(Grant No.ZR2022ME180)the National Natural Science Foundation of China(Grant No.51705267).
文摘High-speed trains operating in freezing rain are highly susceptible to severe ice accretion in the pantograph region,which compromises both power transmission efficiency and dynamic performance.To elucidate the underlying mechanisms of this phenomenon,an Euler-Euler multiphase flow model was employed to simulate droplet impingement and collection on the pantograph surface,while a glaze-ice formation model incorporating wall film dynamics was used to capture the subsequent growth of ice.The effects of key parameters—including liquid water content,ambient temperature,train velocity,and droplet diameter—on the amount and morphology of ice were systematically investigated.The results show that ice accumulation intensifies with increasing liquid water content decreasing ambient temperature,and rising train speed.In contrast,larger droplet diameters reduce the overall ice mass but promote localized accretion on major structural elements.This behavior arises because larger droplets,with greater inertia,are less susceptible to entrainment by airflow into the pantograph's base region.During extended operation,substantial ice buildup develops on the pantograph head and upper and lower arms,severely impairing current collection from the overhead line and hindering the pantograph's lifting and lowering motions.
基金supported by the National Key Laboratory of Advanced Composite Materials(No.KZ42191814)。
文摘The icing characteristics of supercooled large droplet(SLD)impacting carbon fiber-reinforced composites(CFRCs)remain poorly understood,hindering the enhancement of ice protection capabilities and the certification of ice-accreted composite aircraft.The paper systematically investigates the effects of the supercooling degree,the surface temperature,and the impact velocity on the ice accretion behavior of SLDs impacting carbon fiber-reinforced epoxy composite surfaces.To address the ice-prone nature of CFRCs,nanoparticle-modified anti-icing coatings are developed,and the icing characteristics of SLD-impacted modified carbon fiber-reinforced epoxy composite surfaces are analyzed.Results demonstrate that surface-modified carbon fiber-reinforced epoxy composite exhibits significantly delayed ice formation.Under conditions of droplet temperature(−15℃)and surface temperature(−18℃),the icing time of hydrophobic-modified CFRCs was delayed by over 1100 ms,representing a 5.4-fold improvement compared to the unmodified carbon fiber-reinforced epoxy composite.
