板栗真空破壳力学特性有限元分析

以半球形板栗为研究对象,运用有限元方法和传递过程原理建立了板栗真空破壳的有限元模型,并采用间接顺序耦合法对模型进行了求解.模拟与试验结果表明:运用该模型模拟分析板栗真空破壳力学特性可行;真空破壳过程中应力和应变主要沿栗壳边缘分别向弧顶和壳底中心递减分布;湿应力是真空破壳的主导因素;绝对压力对破壳的影响很大,绝对压力的降低不仅使压差应力增大,同时也使湿应力增大.     

行星齿轮轮齿本体温度场与闪温研究

利用齿轮啮合、摩擦学、传热学、赫兹接触等理论,研究了啮合过程中行星齿轮轮齿接触面的相对滑动速度及齿面摩擦因数的变化规律,推导了行星齿轮轮齿齿面接触应力模型。精确计算了轮齿不同啮合位置的摩擦热流密度以及轮齿端面、轮齿齿面等区域的对流换热系数。建立了轮齿本体温度场有限元分析模型,获得了行星齿轮轮齿稳态温度场。分析了标准齿廓和修形齿廓对接触应力及温度场的影响。在稳态热分析的基础上,采用有限元法进行瞬态热分析,得到了啮合过程中轮齿齿面瞬时温度分布。     

Modelling day-to-day stem diameter variation and annual growth of balsam fir (Abies balsamea (L.) Mill.) from daily climate

In the present context of global climate changes and the continuous development of forest management strategies based on the concept of sustainable use, it is important to develop a better understanding of the climatic factors controlling the growth of boreal forests. In this study, we report the results of a five-year field research within which day-to-day balsam fir (Abies balsamea (L.) Mill.) stem diameter variation was measured with dendrometers and examined in relation with various daily climatic variables. A model built with data from three growing seasons that included solar radiation, relative humidity, temperature and precipitation explained 84% of the variance in day-to-day stem diameter variation from June to September. The model has approximately the same predictive capability when validated with independent daily data from two other growing seasons. The model captured both the cumulative increment associated with the irreversible growth and the high frequency variation of day-to-day fluctuations associated to changes in the stem water content. In general, rainy days during which relative humidity was high and solar radiation was low favored stem diameter expansion (growth and swelling) while stem diameter decreased during periods of low relative humidity and high solar radiation. Similar models were obtained when the June-September period was divided into two parts (June-July and August-September) to better represent the period during which most of the cumulative annual stem increment is observed (June-July). Inter-annual variation in stem growth computed from the modeled day-to-day variation in stem diameter was significantly correlated to the inter-annual variation in annual growth determined from tree core measurements over a 10 year period (p = 0.023). The model was notably able to capture a particularly poor growing year (2006) presumably due to a short-term heat stress period. Results suggest that the inclusion of daily data in growth-climate models may contribute to improve predictions of the potential tree growth response to climate by identifying particular climatic events that may escape to a classical dendroclimatic approach.     

蜡梅热激蛋白基因CpHSP1的克隆与表达分析

热激蛋白(heat shock proteins,HSPs)是生物体受高温刺激而合成的一类应激蛋白,根据分子量的大小可分为HSP100s,HSP90s,HSP70s,HSP60s,smHSPs(small HSPs)5大类(Waters et al.,1996).各类HSPs在植物体内普遍存在,其中又以smHSPs最为常见.smHSPs是由核基因编码的一类分子量为15～42ku的HSPs,其典型特征是C端有1个高度保守的ACD(α-crystallin domain)结构,能够快速地对热激刺激产生响应.早期的研究者根据DNA序列相似性分析、免疫交叉反应以及胞内定位方法将smHSPs分为5类,其中2类定位于细胞质,即细胞质I类和细胞质Ⅱ类smHSPs,其余3类分别存在于叶绿体(chlorplastid,CP)、内质网(endoplasmic reticulum,ER)和线粒体(mitochondria,Mt)中(Waters et al., 1996; Sun et al., 2002; Wang et al.,2004 ) .     

番茄钙依赖性蛋白激酶基因LeCPK2在热（光）胁迫中的功能鉴定

钙依赖性蛋白激酶（calcium—dependent protein kinases,CDPKsorCPKs）作为一类钙感知蛋白在植物的生长发育和胁迫应答中起着重要的作用。LeCPK2（Gen Bankaccession No．：GQ205414）是我们从番茄中分离的第3个CDPK基因,前期研究表明LeCPK2可能在植物热胁迫应答中发挥作用。为了进一步研究其在热胁迫中的功能,我们通过电子克隆的方法分离了LeCPK2的启动子序列,并通过LeCPK2过表达烟草分析其在高温胁迫中的潜在的功能。生物信息学分析显示,LeCPK2启动子中包含5个热响应元件,和前期试验结果一致。野生型植株在受到热胁迫后,对光更为敏感,强光照下植株叶片发生萎蔫,而强光本身不会对未受热胁迫的健康植株造成伤害。LeCPK2转基因植株热、光胁迫后不会出现受害表型。以上研究表明,LeCPK2在植物的热胁迫应答中发挥重要作用,能够有效保护植株免受高温胁迫的损害,是一个优秀的耐热（光）基因。本研究将为揭示番茄LeCPK2遗传功能及对其开发利用奠定基础。     

复合抗热应激添加剂对蛋鸡血液生化指标的影响

研究了复合抗热应激添加剂对蛋鸡血液生化指标的影响。Ⅰ、Ⅱ组为试验组 ,Ⅰ组为 0 .5 %中草药 +0 .2 %NaHCO3+ 1%NH4 Cl+ 0 .15 %蛋氨酸 + 0 .0 5 %赖氨酸 ;Ⅱ组为 0 .2 %NaHCO3+ 1%NH4 Cl +多维(2 0 0mg/kgVc + 2 5 0mg/kgVE) ;Ⅲ组为对照组。结果表明 :在热应激条件下 ,I、II组能提高血液Ca2 +、K+、GLU、TG、TP、ALKP、T3水平 ,ALB和CHO水平提高不显著 ;能降低血液Na+、CK、AST、LDH、ALT、T4 、皮质醇水平。     

热处理方式对冬枣货架期品质的影响

通过不同温度热水处理和不同时间热蒸汽处理,研究了热处理方式对冬枣货架期品质的影响.结果表明:53℃热水处理6 min效果最好,不仅延缓冬枣衰老,保持其风味,抑制生理和病理伤害,还可降低腐烂指数、软化率和失水率等.     

冷激处理对芒果贮藏冷害及相关酶的影响

为探讨减轻芒果冷害的新途径,研究了0℃冷激处理3、45、h对芒果2℃贮藏12 d的冷害症状、贮藏品质及3种同工酶的影响。结果表明:0℃冷激处理3、45、h均显著降低了果实在2℃下贮藏期间的冷害指数和冷害率,0℃处理4 h的冷害指数最低,比对照果低60%,冷害率比对照果低32%,0℃冷激处理4 h促进了芒果贮藏期间可溶性固形物含量的上升,降低了可滴定酸的含量,延缓了抗坏血酸的含量的下降,对硬度的影响不大;同工酶电泳显示:0℃冷激处理4 h提高了芒果贮藏中后期ATP酶、细胞色素氧化酶、过氧化物酶的活性。     

低叶绿素含量对突变体水稻吸收光能分配特性的影响

 研究了田间条件下低叶绿素含量水稻突变体及其野生型的PSⅡ光化学效率、热耗散速率等一系列与光化学反应有关的生理过程的日变化,并分析了二者在1d中对吸收光能分配的差异。结果表明,突变体水稻叶片因截光率小而限制了其对光能的吸收,但由于它的电子传递速率比野生型的高,因而部分缓解了它吸收光能不足的不利效应;与野生型水稻相比,突变体水稻叶片所吸收的能量中分配给光化学反应途径的能量较多,而过剩的激发能较少。     

热激处理对微加工蚕豆保鲜效果的研究

褐变和微生物活动是影响微加工蚕豆瓣品质及保鲜效果的主要因素。研究了60℃30、60和120 s热激处理对与其褐变有关的酶及微生物活动的影响。结果表明:采用60℃60 s热激处理效果最佳,可明显降低多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)的活性,抑制褐变度的上升及其表面微生物的活动,延缓Vc含量的下降,从而起到延缓衰老和保持品质的作用。