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.

On the determination and simulation of seawater freezing point temperature under high pressure

At present,it is believed that the freezing point temperature of seawater is a function of salinity and pressure,and the freezing point is a key parameter in a coupled air-sea-ice system.Generally,empirical formulas or methods are used to calculate the freezing point of seawater.Especially in high-pressure situations,e.g.,under a thick ice sheet or ice shelf,the pressure term must be taken into account in the determination of seawater freezing point temperature.This study summarized various methods that have been used to calculate seawater freezing point with high pressure.The methods that were employed in two ocean-ice models were also assessed.We identified the disadvantages of these methods used in these two models and addressed the corresponding uncertainties of the freezing point temperature formulas.This study provides useful information on the calculation of the freezing point temperature in numerical modeling and indicates a need to investigate the sensitivity of numerical simulations to the uncertainties in the freezing point temperature in future.

Chemical Properties,Low-Temperature Performance,and Burning Performance of Bio-Jet Fuel

The effects of composition of bio-jet fuels on freezing point,smoke point,distillation range,and flash point are investigated.Performance tests using petroleum-based jet fuel with different compositions are conducted in line with standard test specifications.The results show that alkylbenzenes reduce the freezing point,with the amount of reduction becoming greater with increasing alkylbenzene content.For a 25%content of the C_8 aromatic xylene,the freezing point is in the range from-55.5℃to-60.1℃.The presence of monocyclic aromatic hydrocarbons leads to an increase in carbon deposition performance,especially when alkyl side chains are present.With cycloalkanes,carbon deposition is reduced,although alkyl side chains weaken this beneficial effect.Isomeric hydrocarbons are beneficial in reducing carbon deposition.The ASTM D7566 specifications for the distillation range are based on the average properties of petroleum-based aviation fuel,and if all the parameters governing the distillation range of an alternative jet fuel are at their lower limits,it is necessary to check whether other performance standards are met.Light components affect the flash point greatly,with 5%of benzene reducing the flash point by 17℃,whereas intermediate components(e.g.,xylene and ethylbenzene)and heavier components have less impact.Although alcohols provide better combustion performance,their content must be strictly limited owing to their effects in reducing the flash point.

Spatial Characteristics of Temperature Indices of Climate Change in China

Based on the temperature indices established by expert group on the detection,monitoring and indices of climate change,spatial characteristics of temperature indices from 278 meteorological stations in China during 1961-2008 were studied.The results showed that day number of freezing point went down gradually from northwest to southeast,as well as the most regions of China.Day number of summer was mostly over 50 d in China and over 100 d in Eastern China except for the most part of Northeast China,while there was an increase trend in the most regions of China.Growth period was generally above 150 d in China and increased with the decrease of latitude from north to south,while the trend coefficient of growth period in 236 stations was positive.

Application of Colligative Properties in Quality Detection of Watering Raw Milk

[ Objective] To investigate the effects of different water amount on freezing point of raw milk. EMetbodl The freezing point of raw milk added water at different proportions was detected by SWC-LG freezing point detector. The linear regression equation was obtained. The reproduc- ibility was checked. The water content in raw milk was calculated according to the standard regression curve. E Result~ When the water content changed from 0 to 10%, the freezing point of raw milk increased linearly. As evidenced by the reproducibility test, the standard deviation and rela- tive standard deviation were less than 1%. The milk concentration obtained by detecting the freezing point of blind milk samples had an absolute er- ror of no more than 0.5%, compared with actual watering milk concentration. [ ConcluMonl Water content in raw milk can be determined by measur- ing freezing point, and this method is reliable and reproducible.

Thermophysical Properties of Channel Catfish at Freezing Temperatures

Freezing is the most common method used to preserve and minimize loss in quality of catfish during storage. Since freezing is a heat transfer process, the design and selection of freezing equipment require knowledge of thermophysical properties such as freezing temperature, enthalpy of freezing, unfreezable water and specific heat. Channel catfish thermophysical properties at freezing temperature were determined using differential scanning calorimetry. Using the combination of Raoult＇s law and Classius-Clapeyron equations, the amount of unfreezable （bound water） was estimated to be 0.129 g H20 g^-1 During freezing （or melting）, the specific heat increased from about 1.5 J g^-1 ℃^-1 to about 30.6 J g^-1 ℃^-1 It was found that freezing of catfish occur over a wide temperature range with the peak and incident freezing temperatures occurring at temperatures of-1.88 ℃ and -6.10 ℃, respectively. About 250 J g^-1 of heat have to be removed from catfish when it is to be frozen to -40 ℃. The implication is that any system that will be designed to freeze catfish must be able to remove 250 J g^-1 of heat.

FREEZING POINT OF LOAD-BEARING MOIST SOIL AND ITS DETERMINATION

Since Workman-Reynolds effect was discovered, more and more attention has been paid to the freezing electrical potential of solution. Hanley and Rao have discussed the freezing electrical potentials and influencing factors, such as the time of solution freezing, ion