咸鸭蛋腌制过程相关指标变化规律及最佳配方的筛选研究

【目的】探究不同腌制条件对咸蛋品质的影响,选出最佳条件,为咸蛋的深加工提供一定的技术参考。 【方法】先用盐酸处理鸭蛋壳,使其蛋壳变薄。并采用分步式腌制方法,即前 11 d 用饱和食盐水腌制,后期用 低浓度的淡盐水腌制,使咸蛋含盐量降低,并添加白酒、香辛料。分别于腌制 11、15、19、23 d 测定蛋白含盐量、 蛋黄出油率、蛋黄指数和蛋黄色度等指标分析其变化规律,通过单因素试验及正交试验确定最佳腌制条件。【结 果】最佳腌制条件为：食盐的质量浓度为 10%、香辛料的质量分数为 0.6%,白酒的体积分数为 5%,盐酸的体 积分数为 0.5%。【结论】采用分步式腌制方法,在上述最佳腌制要件下,腌制 23 d 的咸蛋出油率高、蛋黄指数 大、蛋黄色度深,且具有较低的含盐量,咸蛋品质高。     

新型土壤容重取样器的研制与应用

为了提高土壤容重取样的速度和保障取样质量,研制了新型原位土壤容重取样器,并与传统的环刀法进行了对比测试与分析.结果表明,新型的取样器具有如下优点:(1)结果可靠,T检验结果表明与传统的取样测定方法无显著差异;(2)新型原位土壤容重取样器省工省力,其工作效率比传统的环刀法高出10倍以上.(3)新型土壤容重取样器的扰动面积较小.     

不同培养液对鹅胚胎体外培养的影响

为了探讨不同培养液对鹅胚胎体外培养的影响,本试验分别用鸡、鸭、鹅3种稀蛋白作培养液对90只鹅胚进行体外培养。结果表明：用鹅稀蛋白作培养液优于鸡稀蛋白和鸭稀蛋白。鹅稀蛋白组在第6、15天时鹅胚存活率显著高于鸭稀蛋白组(P<0.05),鹅胚存活率在第6、15天分别为33.33%、20.00%;在第31天时鹅稀蛋白组鹅胚存活率为3.33%,其他两组为0。综上所述,鹅胚体外培养效果因培养液的不同而不同,在鸡、鸭和鹅稀蛋白3种培养液中,以选用鹅稀蛋白为宜。     

稀酸催化蒸汽爆破预处理提高竹子糖化效果的研究

采用稀酸浸泡结合蒸汽爆破预处理方式,对竹子的糖化效果进行了条件筛选。对浸泡酸浓度、浸泡时间、蒸汽爆破压强及、爆破压力维持时间4个因素进行探索,以酶解得到的还原糖含量高低作为衡量指标。结果表明：在单因素实验中,最优条件与其对应的还原糖浓度分别为：浸泡酸浓度2.5%时,还原糖浓度39.4301 g/L;浸泡时间10 h时,还原糖浓度35.2116 g/L;蒸汽爆破压强2 MPa时,还原糖浓度31.7554 g/L;蒸汽爆破压力维持时间150 s时,还原糖浓度30.3634 g/L。通过正交试验优化并验证后,得到最优的预处理条件：常温条件下,将竹子浸泡在2.5%的硫酸中8 h,于压强2 MPa的蒸汽爆破装置中维持180 s后爆破,可以得到最高的还原糖产量42.3707 g/L,且上述单因素影响主次顺序为：浸泡酸浓度＞浸泡时间＞压力维持时间＞爆破压强。     

络合萃取技术及其在生物碱分离中的应用

本文在分析讨论络合萃取技术的基础上,根据该技术对天然产物—生物碱分离研究应用较为薄弱的状况,简要介绍了作者采用络合萃取技术分离苦参碱稀溶液的相系研究结论,并将此技术与传统的分离技术进行了对比。指出,采用络合萃取技术分离广泛存在于植物体的Lewis碱类物质—生物碱,在理论和实践上均具有可行性。     

新型农田风蚀集沙仪排沙口降速问题研究

农田土壤风蚀会导致土壤质量退化,甚至出现荒漠化。防止农田土壤退化,研究其风蚀机理是关键,而集沙仪是研究土壤风蚀的必需仪器。随着自动控制理论在各行业的广泛应用,为集沙仪配备自动采集系统是一个发展趋势。由于集沙仪排沙口气流对称重天平的冲击是引起数据波动的主要来源,所以降低集沙仪排沙口气流速度是很关键的。为此,提出了设计一台新型农田风蚀集沙仪以解决排沙口降速问题的新思路。首先,阐述了新型农田集沙仪的设计原理;随后,通过数值模拟方法对其关键部件风沙分离器进行了数值模拟,得出了其内部速度矢量场模拟图;最后,通过烟流试验和风洞试验对数值模拟结果进行了验证。结果表明:数值模拟结果是可靠的;当新型农田集沙仪受强风环境影响时,其排沙口气流的降速幅度达84%,可较好地缓解排沙口气流对称重天平的冲击。该研究也可为新型农田集沙仪的后续研究提供理论支持。     

Efficacy of a vacuum benthos sampler for collecting demersal fish eggs from gravel substratum

Abstract— We used two densities of eggs (low=900 eggs/m²; high=5100 eggs/m²) in laboratory experiments to estimate the recovery efficiency of the Brown benthos sampler for collecting fish eggs from gravel substrate and to determine if differences (e. g., 5-fold) in egg density in the substratum could be detected with the sampler. The mean egg recovery efficiency of the sampler in the low and high density treatments was 30% (SE=8.7) and 35% (SE=3.8), respectively. The difference between the treatment means was not significant. Therefore, data from the two treatments were pooled and used to estimate the recovery efficiency of the sampler (32.7%, SE=4.4). However, we were able to detect a 5× difference in the number of eggs collected with the sampler between the two treatments. Our estimate of the recovery efficiency of the sampler for collecting fish eggs was less than those reported for the sampler's efficiency for collecting benthic macroinvertebrates. The low recovery efficiency of the sampler for collecting fish eggs does not lessen the utility of the device. Rather, ecologists planning to use the sampler must estimate the recovery efficiency of target fauna, especially if density estimates are to be calculated, because recovery efficiency probably is less than 100%.     

Estimating the probability of freedom of classical swine fever virus of the East-Belgium wild-boar population

A report of the Scientific Committee on Animal Health and Animal Welfare of the European Commission (CEC, 1999.) includes recommendations for setting up monitoring programmes for classical swine fever (CSF) infection in a wild-boar population, based on the assumption that one would detect at least 5% prevalence in a CSF-infected wild-boar population. This assumption, however, is not science based. We propose an alternative method to provide evidence for a wild-boar population being free of CSF and evaluate the efficiency of a surveillance programme that was implemented in Belgium in 1998.

In our study, the probability of freedom of CSF-virus was estimated based on 789 samples; these were collected from wild-boars within the surveillance programme (within the three provinces which include 95% of the Belgian wild-boar population) and examined by three diagnostics methods (antibody detection, virus detection and virus RNA detection). A Bayesian framework was used for the estimation, accounting for the diagnostic test characteristics without the assumption of the presence of a gold standard. The median probability of freedom of CSF-virus was estimated at 0.970, with a 95% credibility interval of 0.149–1.000. Independent on the choice of the prior information, the posterior distributions for the probability of freedom of CSF-virus were always skewed close to the upper boundary of 1. This represents a big gain of knowledge since we did not use any prior information for the probability of freedom of CSF-virus and took the uncertainty about the accuracy of the diagnostic methods into account.     

粉尘多点测试技术在冬季育雏鸡舍内的应用与结果分析

鸡舍内粉尘浓度过高,不仅危害雏鸡和饲养员的健康,还污染鸡舍周围环境。应用多点测试技术对鸡舍内粉尘浓度空间分布进行测量,有助于了解粉尘散发和传播规律、开发除尘方法。本试验采用断面布点和空间均匀布点两种方式,应用多点粉尘测量仪对冬季某育雏舍进行连续监测,同时记录舍内光照时间,并对4个高度上采集的粉尘的直径进行了测量。试验结果表明:断面内粉尘浓度分布受高度和昼夜变化影响;水平面内粉尘浓度值与风速值显著相关(P<0.05)且暖风机附近粉尘浓度较高;0.95m高度上粉尘直径均值最小(29.6μm)。     

渠道运行离散模型及最优控制

当采用计算机在线控制时,控制器由微处理机软件来实现,必须将渠道连续时间系统模型离散化。在渠道连续时间系统模型的基础上,综合考虑水力学和控制学的要求,采用适当的采样器和保持器,推导出渠道离散时间系统模型。将最优控制理论应用到渠道离散系统运行管理中设计出最优控制器,通过模拟仿真,验证所建立的渠道运行控制理论和设计方法是可行的。