不同频率下超声波水处理对苹果内传热传质影响规律的试验研究

为探究超声波处理对果蔬加工过程中热质传递的影响规律,以苹果为研究对象,结合不同频率（40、68、80 kHz）超声波处理技术,分别进行超声波辅助低温水浴试验和超声波水预冷处理辅助苹果片真空冷冻干燥试验。结果表明：超声波辅助低温水浴可有效强化苹果与冷水间的热量交换,频率为80 kHz时,苹果果肉中部和近果核处的冷却系数与对照组相比分别增加了35.3%和28.6%;超声波水预冷处理后,真空冷冻干燥过程有效水分扩散系数比对照组分别增加了51.6%（超声波频率40 kHz）、55.9%（超声波频率68 kHz）、58.7%（超声波频率80 kHz）。     

Lipid characterization of both wild and cultured eggs of cuttlefish (Sepia officinalis L.) throughout the embryonic development

The present work reports a characterization of mean wet weight and moisture, the lipid class and fatty acid (FA) composition from the total lipids (TL), of both culture and wild eggs of the cuttlefish, Sepia officinalis , throughout the embryonic development. Additionally, reproductive data, such as the number of spawnings, number and mean weight of eggs and duration of spawning period of cultured cuttlefish is provided. Both types of eggs were similar in mean wet weight, moisture content, TL content and lipid composition throughout embryonic development. Females from the cultured group spawned 13 times and laid 8654 eggs in 64 days, with a mean weight of 0.607 ± 0.179 g. A sex ratio of 1.57 (11♀ for 7♂) promoted an individual fecundity of 787 eggs/♀ (the biggest until now on our culture facilities), which might be related to increased bottom areas. The TL increased with day/stage of embryonic development ( P  < 0.05) only in the cultured egg group. However, no differences were found on TL between culture and wild eggs at the same day/stage ( P  > 0.05). Eggs displayed predominant levels of phosphatidylcholine, phosphatidylethanolamine (PE), cholesterol and triacylglycerol at the end of embryonic development. Polar and neutral lipids of both eggs groups remained consistently proportional (∼50% for each lipid fraction) and a significant increase ( P  < 0.05) was observed in phosphatidylserine, PE and free FA throughout the embryonic development. In either egg type and day, 16:0, 18:0, 20:5n-3 and 22:6n-3 accounted for approximately 70 g Kg⁻¹ of all FA and saturated and n-3 totals seemed to have the same proportion in the cuttlefish eggs. The present results suggest that lipids are not used as energetic substrate but as structural components in cuttlefish egg.     

Annual cycles of germinability and differences between primary and secondary dormancy in buried seeds of Echinochloa crus-galli

The seasonal changes in percentage of dormant seeds of Echinochloa crus-galli in the field were recorded for 4 years. The lots of seeds were wrapped in nylon fabric, buried 20 cm under the grass sward and exhumed at monthly intervals. The proportion of seeds germinating under light conditions at a constant temperature of 25 °C fluctuated between 0% and 96%, with maxima in May–July and minima in September–November. Small between-year differences in the course of summer dormancy induction and its winter termination were probably caused by variation of weather conditions.
Attributes of dormancy innate to seeds after maturation (primary dormancy) and dormancy induced in buried seeds during the summer (secondary dormancy) were compared by investigating the rate of dormancy termination during storage of (a) dry seeds at 25 °C, (b) imbibed seeds at 5°C and (c) in seeds buried under field conditions during October–June. Percentage of germination increased faster in secondary than primary dormant seeds at both constant 25 °C and 5 °C. The seeds with primary and secondary dormancy also differed in the response to `germination pre-treatment', a 10-day exposure of imbibed seeds at 25 °C that causes germination of the non-dormant fraction of seed materials. After this treatment the time to resuming germination in primary dormant seeds was substantially increased, whereas the secondary dormant seeds were much less affected. Annual variation in the proportion of germinable seeds explains the low efficiency of autumn soil cultivation for decreasing reserves of E. crus-galli seeds in the soil.     

Influence of crop management on eyespot development and infection cycles of winter wheat

Wheat was assessed at four crop growth stages for eyespot (anamorph Pseudocercosporella herpotrichoides, teleomorph Tapesia yallundae) in a series of field trials that studied the effects on disease frequency of five wheat management techniques (sowing date and density, nitrogen fertiliser dose and form, removal/burial of cereal straw). An equation expressing disease level as a function of degree-days was fitted to the observed disease levels. This equation was based on eyespot epidemiology and depended on two parameters illustrating the importance of the primary and the secondary infection cycles respectively. Cultural practices were classified according to the importance of their effects on disease, and these effects could be related to infection cycles and host plant architecture. Sowing date had the earliest and strongest effect; early sowing always increased disease frequency through the primary infection cycle, and its influence on the secondary cycle was variable. Disease frequency was increased by high plant density and/or a low shoot number per plant through primary infection; the secondary cycle was, however, decreased by a low shoot number per plant, which reduced late disease development at high plant density. High nitrogen doses increased disease levels and the severity of both infection cycles, but this effect was partly hidden by a simultaneous stimulation of tillering and thus an indirect decrease of disease incidence. When significant, ammonium (vs ammonium nitrate) fertiliser decreased eyespot levels and infection cycles whereas straw treatment (burial vs removal of straw from the previous cereal crop) had no effect.     

垂榆冻害调查及其影响因素的分析

对长春市4个不同地点(路段)栽植垂榆的受冻害状况进行了调查与分析,结果表明:4个调查地点垂榆的冻害率分别为67.0%、31.0%、72.0%和92.0%,平均值为65.5%;冻害指数分别为31.0、11.4、49.2和64.9,平均值为39.1。2009~2010年冬春季节持续低温的累积作用是导致发生冻害的主要因素,老龄植株生长后期的嫁接不亲和作用与砧木个体抗寒能力的遗传差异亦是影响因素之一。     

Optimization of Freeze-drying Protective Agents for Lactobacillus plantarum KLDS1.0391 by Response Surface Methodology

In this study, the Single Factor Test(SFT) was used to optimize the pre-freezing conditions of L. plantarum KLDS1.0391(KLDS1.0391). Further, the Freeze-Drying Protective Agents(FDPA) of KLDS1.0391 was optimized by Response Surface Methodology(RSM). The optimum pretreatment conditions were as the follows: initial concentration of KLDS1.0391 was 1011 CFU · m L~(-1) and KLDS1.0391 was pre-freezed at –80℃ for 8 h to achieve the survival rate of 46.21%. The main components of FDPA were skim milk, sucrose, sodium glutamate and Tween-80. And the influence of four factors on the survival rate of KLDS1.0391 in freeze-drying was in order as the follows: skim milksucroseTween-80sodium glutamate. The optimal FDPA composition was skim milk 11.3%, sucrose 9.8%, sodium glutamate 5.1% and Tween-80 0.2%. Under the above conditions, the survival rate of the cells was 82.98%. Comparing the predicted values, the relative error was 0.37% and the difference was not significant, which indicated that the established model could effectively reflect the actual protection of FDPA to KLDS1.0391.     

基于遗传算法的苦瓜片真空冷冻干燥工艺优化

为提高苦瓜片干制品品质，应用真空冷冻干燥技术对新鲜苦瓜片进行干燥，以得到最佳工艺参数。采用响应面分析法设计四因素三水平试验，对苦瓜片试验指标（含水率和复水比）和干燥工艺参数（切片厚度、温度、绝对压强和干燥时间）建立二次多项式回归模型，并对模型的有效性及因素间的交互作用进行分析，利用Matlab中的遗传算法对结果进行综合优化。结果表明：建立的回归方程拟合度较好，模型显著，所得工艺参数合理可用。苦瓜片真空冷冻干燥的最佳工艺参数为：切片厚度为4mm，隔板温度为46℃，绝对压强为73Pa，干燥时间为8.7h。该条件下含水率为6.23%，复水比为11.75。     

Microbial hotspots and hot moments in soil: Concept & review

Soils are the most heterogeneous parts of the biosphere, with an extremely high differentiation of properties and processes within nano- to macroscales. The spatial and temporal heterogeneity of input of labile organics by plants creates microbial hotspots over short periods of time – the hot moments. We define microbial hotspots as small soil volumes with much faster process rates and much more intensive interactions compared to the average soil conditions. Such hotspots are found in the rhizosphere, detritusphere, biopores (including drilosphere) and on aggregate surfaces, but hotspots are frequently of mixed origin. Hot moments are short-term events or sequences of events inducing accelerated process rates as compared to the average rates. Thus, hotspots and hot moments are defined by dynamic characteristics, i.e. by process rates.For this hotspot concept we extensively reviewed and examined the localization and size of hotspots, spatial distribution and visualization approaches, transport of labile C to and from hotspots, lifetime and process intensities, with a special focus on process rates and microbial activities. The fraction of active microorganisms in hotspots is 2–20 times higher than in the bulk soil, and their specific activities (i.e. respiration, microbial growth, mineralization potential, enzyme activities, RNA/DNA ratio) may also be much higher. The duration of hot moments in the rhizosphere is limited and is controlled by the length of the input of labile organics. It can last a few hours up to a few days. In the detritusphere, however, the duration of hot moments is regulated by the output – by decomposition rates of litter – and lasts for weeks and months. Hot moments induce succession in microbial communities and intense intra- and interspecific competition affecting C use efficiency, microbial growth and turnover. The faster turnover and lower C use efficiency in hotspots counterbalances the high C inputs, leading to the absence of strong increases in C stocks. Consequently, the intensification of fluxes is much stronger than the increase of pools. Maintenance of stoichiometric ratios by accelerated microbial growth in hotspots requires additional nutrients (e.g. N and P), causing their microbial mining from soil organic matter, i.e. priming effects. Consequently, priming effects are localized in microbial hotspots and are consequences of hot moments. We estimated the contribution of the hotspots to the whole soil profile and suggested that, irrespective of their volume, the hotspots are mainly responsible for the ecologically relevant processes in soil. By this review, we raised the importance of concepts and ecological theory of distribution and functioning of microorganisms in soil.     

Autumn frost hardiness of Pinus sylvestris offspring from seed orchard grafts of different ages

Autumn frost hardiness of offspring from clones (originating from 66.0–68.8° N) in six southern (62° N) and one northern (66.5° N) Pinus sylvestris seed orchards in Finland, was evaluated. One‐year‐old seedlings derived from open pollinated grafts of young, intermediate, and fairly mature age, and natural stand seedlings, were artificially freeze tested. The northerly located orchard produced the least injured offspring. There were no significant systematic differences between age classes. Neither were there any indications of decreased freezing injury with later age classes. The family variance was significant in four orchards. The estimated injury levels of orchard offspring were, in general, closer to those of natural stands in the neighbourhood of the orchard than natural stands at the place of clonal origin. It is suggested that not only differences in mother clone hardiness but also clonal differences in pollen contamination rate caused the observed family variation.