Study on Supercooling Point and Freezing Point in Floral Organs of Apricot

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.

Supercooling Suppression of Microencapsulated n-Alkanes by Introducing an Organic Gelator

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.

Suppression of supercooling of PCM-water emulsions using nano-additives

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.

Solidification characteristics of near rapid and supercooling directional solidification

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.

A Study of Water Supercooling

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.

Nucleation of Supercooled Water by Neutrons: Latitude Dependence and Implications for Cloud Modelling

It has recently been shown that incident particles, neutrons, can initiate the freezing in a supercooled water volume. This new finding may have ramifications for the interpretation of both experimental data on the nucleation of laboratory samples of supercooled water and perhaps more importantly on the interpretation of ice nucleation involved in cloud physics. For example, if some fraction of the cloud nucleation previously attributed to dust, soot, or aerosols has been caused by cosmogenic neutrons, fresh consideration is required in the context of climate models. Moreover, as cosmogenic neutrons, most being muon-induced, have much greater flux at high latitudes, estimates of ice nucleates in these regions may be larger than required to accurately model cloud and condensation properties. This discrepancy has been pointed out in IPCC reports. Our paper discusses the connection between the new concept of neutrons nucleating supercooled water and the need for a new source of nucleation in high latitude clouds, ideally causing others to review current data, or to analyse future data with this idea in mind. .

Assessing the supercooling of fresh-cut onions at−5℃ using electrical impedance analysis

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℃.

Aircraft Observation and Simulation of the Supercooled Liquid Water Layer in a Warm Conveyor Belt over North China

This paper studied a snow event over North China on 21 February 2017,using aircraft in-situ data,a Lagrangian analysis tool,and WRF simulations with different microphysical schemes to investigate the supercooled layer of warm conveyor belts(WCBs).Based on the aircraft data,we found a fine vertical structure within clouds in the WCB and highlighted a 1-2 km thin supercooled liquid water layer with a maximum Liquid Water Content(LWC) exceeding0.5 g kg^(-1) during the vertical aircraft observation.Although the main features of thermodynamic profiles were essentially captured by both modeling schemes,the microphysical quantities exhibited large diversity with different microphysics schemes.The conventional Morrison two-moment scheme showed remarkable agreement with in-situ observations,both in terms of the thermodynamic structure and the supercooled liquid water layer.However,the microphysical structure of the WCB clouds,in terms of LWC and IWC,was not apparent in HUJI fast bin scheme.To reduce such uncertainty,future work may focus on improving the representation of microphysics in bin schemes with in-situ data and using similar assumptions for all schemes to isolate the impact of physics.

Study on Supercooling of Flower Buds of Camellia yuhsienensis

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

Mechanism of supercooling in flower bud of Camellia oleifea

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.

Effect of mixing temperature on microstructure of an Al-Si alloy prepared by controlled diffusion solidification

The effects of mixing temperature,i.e.,the temperatures of two precursor melts(pure Al and Al-12Si),on the temperature and solute fields of resultant mixture,the nucleation and growth,and the size and morphology of primary grains during controlled diffusion solidification(CDS) of Al-8Si alloy were investigated by using simulation and calculation.The results indicate that a lower mixing temperature is helpful for achieving more supercooled microscale Al-rich pockets in the mixture,and increasing the width and supercooling degree of supercooling zone in the Al-rich pockets,and thus,the nucleation rate.The nuclei grow up in nondendritic mode,resulting in spheroidal,at least,nondendritic grains.In a successful CDS,the superheat degrees of the two precursor melts should be limited within several degrees,and it is not necessary to extra stipulate the superheat degree of target alloy melt(Al-8Si) when the requirement about Gibbs energies of the three melts is matched.Subsequent observation on casting microstructures shows that the employed simulation and calculation processes are reasonable and the achieved results are reliable.

TRANSFORMATION OF CRYSTAL MORPHOLOGY OF EUTECTIC COMPOSITE-IN-SITU

It is clarified by experimental examination and theoretical analysis that the transformation of crystal moorphology of the eutectic Al-Cu alloy composite-in-situ seems to be judged by not only the constitutional supercooling proposed in previous literatures but also the supercooling due to the effect of curved surfaces at the solidifying from.The greater entropy of fusion and the tendency to faceted face are important features of the non-metallic phase,which may con- tribute to the leading,role of the phase during solidification.It might be the change of leading phase that changes the morphology of crystals.

Effect of Rapid Cold Hardening on the Cold Tolerance of the Larvae of the Rice Stem Borer,Chilo suppressalis(Walker)

The effects of rapid cold hardening （RCH） on the cold tolerance of the last instar larvae of Chilo suppressalis （Walker） were evaluated for the first time. The discriminating temperature, induction, detection, duration and extent of RCH of the larvae in the laboratory were tested, and the supercooling points （SCPs） and the contents of water and lipid of the larvae after RCH treatment were determined, respectively. The results showed that the discriminating temperature of the larvae was about -21℃. Mean survival rates of the larvae which exposed to either 0 or 5℃ for 2 and 4 h before exposure to the discriminating temperature for 2 h were significantly higher than those of the control groups （P 〈 0.05）. Moreover, the highest survival rate appeared in the larvae after 0℃ for 4 h treatment. The protection against low temperature gained by RCH at 0℃ for 4 h was rapidly lost on return to 28℃. Mean survival rates of RCH larvae were significantly higher than those of non-acclimated （NACC） larvae and acclimation （ACC） larvae when they were exposed to the discriminating temperature for 2 or 4 h （P〈 0.05）. Moreover, the rates of NACC, ACC, RCH and ACC ＋ RCH larvae from 2 to 6 h to the discriminating temperature resulted in a significant decline. The values of SCPs and the contents of lipid of the larvae which exposed to either 0 or 5℃ for 2 and 4 h showed no significant difference at 0.05 level compared to those of the control groups. But the contents of water in the larvae were obviously decreased. Therefore, it could be concluded that RCH could enhance cold tolerance and affect partly physiological and biochemical components of the larvae of C. suppressalis, but the underlying mechanisms needs to be further explored.

Influence of yttrium on the structure and magnetostriction of Fe_(83)Ga_(17) alloy

Polycrystalline Fe83Ga17 alloy rods with various amounts of yttrium were prepared by high vacuum induction melting. It is found that yttrium addition has a significant effect on the structure and magnetostriction of Fes3Ga17 alloy. The small addition of yttrium alters the solidification character and the grain shape of Fe83Ga17 alloy, and as a result, columnar grains with the 〈100〉 preferential direction are pro- duced. Yttrium addition improves the magnetostrictive performance of the as-cast Fes3Ga17 alloy. The magnetostriction values of the as-cast alloy with 0.32at% and 0.64at% yttrium addition go up to 119×10^-6 and 137×10^-6 under 15 MPa compressive stress, respectively. The energy dispersive spectroscopy （EDS） result shows that almost all of the yttrium atoms exist in the Y2Fe17-xGax phase. A small amount of this kind of secondary phase cannot obviously increase the saturate magnetic field.

Cold hardiness of the invasive fall armyworm,Spodoptera frugiperda in China

Fall armyworm,Spodoptera frugiperda(J.E.Smith,1797),a crop pest native to tropical and subtropical regions of America,has invaded and spread into most regions in China,posing a severe threat to China’s agriculture.The cold hardiness directly determines its geographic distribution through adapting to winter temperatures of different regions.Here,we measured supercooling points and lethal time(LT)at low temperatures of S.frugiperda.The supercooling points for developmental stages in increasing order were:adults(-15.05℃)<pupae(-13.25℃)<prepupae(-10.50℃)<larvae(-9.03℃).Among eggs and 1st to 4th in star larvae,the 99%lethal time(LT_(99))was the highest for 4th in star larvae,with 99%of larvae dying after 18.59 d at 2℃,58.72 d at 7℃,and 66.28 d at 13℃.LT_(99) was the lowest for eggs with LTgg of 5.33 d at 2℃,9.28 d at 7℃,and 12.97 d at 13℃.This study provides mn understanding of overwintering regions of S.frugiperda in China which will be helpful for population forecasting and management.

Effects of Ni addition on liquid phase separation and giant magnetoresistance of Cu-Co alloys

The effects of Ni addition on the liquid phase separation and giant magnetoresi stance (GMR) of Cu Co alloys were discussed. The results reveal that Ni additio n can partially restrain the liquid phase separation of Cu Co alloys, resultin g in a decrease of volume fraction for the Co rich particles separated from the liquid phase and in refined microstructures. The composition analyses indicate t hat Ni is dissolved in both the Co rich and the Cu rich phases, but Ni content in the Co rich phase is much higher than that in the Cu matrix. At the same ti me, Ni addition enhance the solubility between Cu and Co, especially Cu in Co s olid solution. Ni alloying into Cu Co alloys can fully prevent the liquid phase separation during melt spinning, which is very beneficial to improve GMR of Cu Co alloys.

SUPERCOOL织物与纯棉织物吸水透气性能比较

将SUPERCOOL短纤纱织成纬平针组织,并对织物进行染整处理,测试其基本结构特征参数,用毛细效应法和比利时UCB法来比较SUPERCOOL织物的吸水性能,测试分析其透气性能,并与同纤度纯棉针织物相比较。结果表明:SUPERCOOL织物具有优异的吸水及透气性能。

Sub-bandgap photocurrent response and carrier transport properties of undoped semi-insulating LEG GaAs as a composite

Undoped (ND) semi-insulating (SI) liquid encapsulated Czochralski (LEC) GaAscrystals were investigated by photocurrent and temperature-dependent Hall measurements. It isindicated that strong nonuniformities in the distributions of impurities and defects can occur forthe NDSILEC GaAs crystal grown under a condition with strong constitutional supercooling. In suchcase, the deep level that dominates Fermi level is spacial location dependent, and the GaAs crystalbecomes a composite consisting of a large number of elementary domains with differentconductivities. The sub-bandgap photocurrent response and the carrier transport properties for thiskind of composite are quite different from those for homogeneous NDSILEC GaAs.

Supercool聚酯纤维/棉/羊绒双面色织面料的开发

利用Supercool聚酯纤维的特性,以Supercool聚酯纤维/棉混纺纱为经纱,棉/羊绒混纺纱、丝光烧毛纱为纬纱,开发双面色织面料。Supercool聚酯纤维/棉混纺纱具有优良的吸湿排汗特性,且毛羽少、强力高、耐磨性好,免上浆,免退浆,缩短了生产工艺流程。通过优化纱线配置,合理设置工艺参数,解决了布面易起泡的问题。所开发的织物充分发挥3种纤维的综合优势,正面光滑平整,反面柔软保暖,吸湿排汗性好,抗皱性强,抗静电且不易起毛起球,具有优异的服用性能。产品生产实现低碳环保,节时高效,符合清洁生产的潮流。

Supercool~纤维纬平针织物性能分析

将具有导湿快干性能的Supercool短纤维与棉以50∶50的比例制成14.5 tex纱线,在Z201E型台车上编织成纬平针织物,对比分析此织物与纯棉纬平针织物染整加工前后基本结构参数、吸水性能和透气性能的变化。结果显示,纯棉坯布的基本结构参数比Supercool坯布的稍显紧密,这两种织物经染整加工后,组织结构紧密度均会发生变化;无论是坯布还是成品布,Supercool织物的吸水性能和透气性能均优于纯棉织物的;染整加工会使这两种织物的吸水性能不同程度地增加,但会不同程度降低这两种织物的透气性能。