浊度法鉴定牛乳中复原乳成分初探

当溶液中加入无机盐或无机酸时，乳清蛋白和酪蛋白分离，样品用硫酸铵处理、过滤、加热后得到滤液，测定滤液浊度值。根据牛奶加热方式的不同，其蛋白变性存在一定的差异，表现为牛奶的白浊度明显不同，因而可用浊度仪来测定。实验表明，本方法具有快速、简单的特点，在鉴定牛乳中复原乳成分方面提供了一个实用的方法。     

Influence of turbidity and fluctuating water levels on the abundance and depth distribution of small, benthic fish in New Zealand alpine lakes

Abstract –  Minnow trapping was used to determine the distribution and abundance of two small, benthic species of fish, common bullies ( Gobiomorphus cotidianus ) and koaro ( Galaxias brevipinnis ), in five oligotrophic lakes varying in both turbidity and the extent of water-level variation. Koaro were 5–20 times more abundant in the large turbid lakes than in the clear ones, indicating that turbidity may reduce the extent of salmonid predation on koaro. However, the scarcity of koaro in the clear lakes was related mainly to the prevalence of brown trout ( Salmo trutta ) compared with rainbow trout ( Oncorhynchus mykiss ) as the former were more piscivorous and had a stronger inverse relationship with koaro. Common bullies were more abundant at sites 20 m or more away from the shoreline, and at depths of 9–12 m irrespective of season, year and turbidity level. However, the overall abundance of bullies was reduced by 70–90% in the turbid lakes. As bullies are relatively insensitive to the direct effects of increased turbidity, indirect effects such as reductions in macrophytes from reduced water clarity or smothering of benthic habitats by settled solids are thought to influence their abundance in the lakes affected by glacial turbidity. There was no relationship between the extent of water-level fluctuation and the abundance of koaro or common bullies in the lakes, but the depth distribution of bullies was shallowest in the lake with the least water-level fluctuation and was deepest in the lake with the greatest water-level fluctuation.     

液体茶饮料提取技术的试验研究

液体茶饮料的提取技术影响着产品的色香味和澄清度,而产品在常温下保存易产生浑浊沉淀,影响其商品价值。试验研究表明,用β-CD溶液在常温下进行茶叶提取,使提取液既能保持茶叶原有的良好品质,同时在常温下保存,也不容易出现混浊和沉淀。     

福建省农村地区高浊度原水净化实验研究

农村饮水工程的水源主要来自坡地汇流、溪河、山塘水库及地下水等,水质与自然地质、水文以及气候条件息息相关。由于农村地区净水工艺和设备往往较为简易、落后,高浊度水是水厂制水过程中普遍存在且较难处理的主要问题之一,因而优化高浊度水的净水工艺是提升农村饮水工程水质的重要一环。本文通过实验条件下研究高浊度水的应急制水技术,提出改进高浊度水净水方案,为福建省农村地区高浊度水处理设计应用开辟新的途径。     

A review of diagnostic tests for diagnosing failure of transfer of passive immunity in dairy calves in New Zealand

ABSTRACT

The aim of this review is to critically assess the test characteristics and practicality of published data on direct and indirect tests for diagnosing failure of transfer of passive immunity (FPT) in dairy calves in New Zealand, to provide recommendations for veterinary practitioners, and to examine the recommended sample size for assessing herd-level prevalence of FPT and the confidence in the results obtained. The definition of FPT is based on measurement of concentrations of IgG in serum of neonatal calves after colostrum intake. The gold standard method for measurement of concentrations of IgG is radial immunodiffusion. However its cost, requirements for laboratory equipment, and the time taken to obtain results have meant that alternative tests have been developed. The turbidimetric immunoassay and ELISA also directly measure concentrations of IgG. Indirect tests include measurement of concentrations of total proteins (TP) in the laboratory or using a refractometer, γ-glutamyl transferase (GGT) activity, and the zinc sulfate turbidity (ZST) test. Of the indirect tests, measurement of concentrations of TP in the laboratory or using a refractometer combine high specificity and sensitivity with a consistent association with concentrations of IgG in calves between 1–7 days of age. Using a refractometer is less accurate than direct measurement in a laboratory, but is still a suitable test if low cost and speed are important. Although GGT activity is strongly associated with concentrations of IgG in serum, the relationship varies with time after birth. Therefore the target thresholds change with time, increasing error compared to the measurement of concentrations of TP in serum. Similarly, factors other than total concentrations of IgG have a significant effect on the association with ZST test, complicating interpretation. Thus, when direct measurement of concentrations of IgG is not feasible, the recommendation is that concentrations of TP in serum should be used as the diagnostic test for diagnosis of FPT, providing calves are not dehydrated. Using a sample size of 12 calves is suitable for estimating whether the herd-level prevalence of FPT is <20% or >20%, if there are no calves or >5 calves diagnosed with FPT, respectively, but is limited in diagnostic confidence when 1–4 calves test positive. Diagnostic interpretation can be significantly improved if tests of FPT are used alongside information on the likely risk of FPT on the tested farm.     

大豆糖蜜澄清工艺的研究

为了利用大豆糖蜜发酵生产单细胞蛋白,对大豆糖蜜的澄清工艺进行了研究。以除浊率和脱色率为指标,研究了稀释浓度、加酸种类、pH值、加热温度对大豆糖蜜澄清效果的影响。结果表明,加酸种类对澄清效果影响不显著,稀释浓度、pH值、加热温度对大豆糖蜜澄清效果影响显著。最佳澄清工艺条件为:在大豆糖蜜质量分数15%,用磷酸调pH值至3.5,在80℃恒温水浴30min,大豆糖蜜的除浊率为99.24%,脱色率为95.18%。     

春季江汉平原草鱼浮头泛塘指标及成因初探

为了获得春季江汉平原草鱼浮头泛塘的溶氧量指标,在荆州农业气象试验站开展了草鱼浮头泛塘模拟试验。试验结果表明：草鱼发生浮头时临界溶氧量为0.30 mg/L,发生泛塘时为0.10 mg/L,持续时间在30 min以上;研究还发现：水质浑浊度与水体溶氧能力有着直接的联系,经14 h增氧处理后池塘水溶氧量增量比轻度浑浊的自来水高1.98 mg/L,经过换水处理后的自来水溶氧量提升了1.2~1.6 mg/L。因此,在春季池塘水产养殖中,水质改良对鱼类的生活环境有较大的改善,同时也会在一定程度上延缓或减少浮头泛塘的发生,从而避免较大的经济损失。     

应用浊度法快速鉴别原料乳、巴氏乳和UHT乳

试验采用浊度法来鉴别原料乳、巴氏乳及UHT乳。螯合盐对不同热处理的牛乳处理后显示出不同的浊度,根据这一特性筛选出可以较好区分原料乳、巴氏乳及UHT乳的螯合盐,该检测方法的原理为螯合盐主要通过螯合了牛乳中的钙、对酪蛋白胶粒进行了分散,并形成了一种新的螯合盐和钙的复合物,改变了酪蛋白的特性。结果显示柠檬酸盐（柠檬酸三钠、柠檬酸铵）和磷酸盐（六偏磷酸钠、多聚磷酸钠、焦磷酸钠）可以很好将牛乳中的酪蛋白胶粒进行分散,分散后的胶体溶液呈现出可以定量测量的浊度,但柠檬酸三钠对原料乳、巴氏乳和UHT乳分散后浊度的区分最为明显,D_{600 nm}值在0～0.15之间为原料乳,0.20～0.50之间为巴氏乳,0.60～1.00之间为UHT乳。浊度法可以快速的鉴别原料乳、巴氏乳和UHT乳,且操作简便,检测速度快,费用低。     

浊度法快速测定水产饲料耐水性方法研究

通过试验建立了一种快速测定饲料耐水性的方法。由崩解仪加快饲料在水中的溃散,然后用浊度仪测其相对浊度比。结果表明:相对浊度比能全面反映饲料的耐水性能,与传统测试方法的相关系数r=0.9678;测试时间由传统测定所需的7～8h缩短为0.5h,检测重现性较好(不同样品测定的变异系数小于5%),具有方法快速、操作简便、成本低等特点,适于推广使用。     

岭南妇科带下病论治特色

岭南妇科带下病发病受岭南地区气候特点影响,证治有自身的特点,以湿为主,且易反复。辨证多以化湿除浊,补清兼施,调理五脏,以肝脾为宗;用药多选用轻清芳香,甘平清淡,少用苦寒辛温之品;且提出“药食结合”扶正祛邪以巩固带下病的调护方法。