屠宰猪肝脏组织中戊型肝炎病毒的检测

摘要：戊型肝炎是由戊型肝炎病毒（hepatitis E virus ,HEV）引起的一种人兽互传病毒性肝炎,主要经消化道传播,猪等多种与人类密切接触的动物均可感染。为了解屠宰商品猪肝脏中HEV的感染情况,从北京、河北和河南的屠宰场共采集了581头屠宰猪的肝脏,猪源分别来自黑龙江、吉林、辽宁、河北、北京等地的集约化猪场,河南的个体散养户和集约化猪场饲养的商品猪。每头猪取样两份,一份固定,做石蜡切片,用抗-人HEV抗体做肝脏中HEV免疫组织化学染色,另一份冷冻保存,提取病毒核酸,进行RT-PCR。结果发现,六个地区的屠宰猪肝脏HEV免疫组织化学阳性率除了河南散户为33.3%外,其它都在90%以上,最高达到100%。应用针对HEV ORF2区设计的通用引物,从部分样品中检测到了HEV核酸的存在。表明戊型肝炎在以上地区的商品屠宰猪中普遍存在,对猪肉品安全构成了威胁,应予以关注。     

Detection of castor contamination by real-time polymerase chain reaction

Due to the potential for intentional contamination of food with crude preparations containing ricin, a real-time PCR method was developed for the detection of castor plant material in ground beef. One primer pair was identified and confirmed to be castor-specific and efficient for amplification of ricin in DNA extracts from castor or beef matrices. Of three different DNA extraction protocols compared, the hexadecyltrimethylammonium bromide (CTAB) method yielded the highest quality of DNA for QPCR assay. The detection limit for castor contamination in ground beef samples was <0.001% (<10 microg of castor acetone powder per gram of beef, corresponding to 0.5 microg of ricin), indicating excellent sensitivity for the assay, well below the threshold for oral toxicity.     

基于红外热像的瓷绝缘子污秽等级检测方法

为解决目前绝缘子污秽等级检测方法操作繁琐、漏判率高的问题,提出了一种基于红外热像处理的瓷绝缘子污秽等级检测方法。首先,将现场拍摄的绝缘子红外热像图进行二步法去噪;然后,针对绝缘子红外热像的颜色特征,采用RGB图像中的R分量图以及改进的OTSU分割算法获取二值图像,再对二值图像进行两次数学形态学修正,得到绝缘子积污区域。利用统计学方法提取积污区域R通道的5个特征分量,并对BP神经网络进行训练,建立绝缘子污秽等级判别网络。选取5个污秽等级的XP-70瓷绝缘子红外热像图共500组作为试验样本,对该系统进行反复测试,总识别精度达到91%以上。     

Detection of polycyclic aromatic hydrocarbon levels in milk collected near potential contamination sources

Polycyclic aromatic hydrocarbons (PAHs), mainly formed by incomplete anthropogenic organic matter combustion, are ubiquitous in the environment. To assess milk PAH contamination sources, milk samples were collected from the tank milk at farms located near potential contaminating emission sources such as cementworks, steelworks, and motorways. PAH analyses were carried out by gas chromatography coupled to mass spectrometry. Eight PAHs were identified in milk: naphthalene, acenaphthylene, acenaphthene, fluorene, anthracene, fluoranthene, pyrene, and benzo[a]anthracene. For all potential contaminating sources, these eight PAHs were detected with similar profiles and at low concentrations except for fluorene and naphthalene, for which source-molecule interaction is pointed out.     

颗粒饲料淀粉糊化度的快速检测方法

淀粉糊化度是评价颗粒饲料加工质量的重要指标,直接影响畜禽吸收利用饲料中能量物质的效率,进而影响饲料的转化效率和畜禽生长状态。该文建立了颗粒饲料淀粉糊化度的两种快速检测方法,其中近红外光谱分析方法（NIRS）检测淀粉糊化度的定标和验证模型的决定系数（R2）分别为0.8759和0.9608;而快速黏度分析法（RVA）预测淀粉糊化度的定标和验证模型的决定系数分别为0.8025和0.8746。试验结果表明近红外光谱分析技术和快速黏度分析法均可快速且较准确地预测颗粒饲料的淀粉糊化度,在一定程度上能较好地满足实时监测饲料加工过程淀粉糊化程度、实现颗粒饲料精细加工的需要。     

Gas-liquid chromatographic determination of diethylstilbestrol in molasses-based liquid feed supplements.

A gas-liquid chromatographic (GLC) method is described for the determination of diethylstilbestrol (DES) in molasses-based liquid feed supplements, using dienestrol diacetate as the internal standard. A sample equivalent to 110 mug DES was diluted, acidified with dilute sulfuric acid, extracted with chloroform, and subjected to basic sodium acetate cleanup. The bis-(trimethylsilyl) acetamide derivative was prepared and determined by GLC. Interfering peaks and/or low recoveries were found to be related to emulsions and the procedure incorporates centrifugation to minimize these.     

Co-composting of swine mortalities with swine manure and sawdust

The treatment of livestock fatalities caused by epidemic diseases must be timely. Simultaneously, the contaminated excreta and bedding materials must also be treated on site without removal. The composting of manure with bulking materials is widely used on the farm, and the temperature during the composting reaches over 60°C under appropriate conditions of moisture and oxygen, with a suitable carbon to nitrogen ratio. These characteristics of composting can be applied to the degradation of dead livestock. Hence, this study was conducted to evaluate the degradability of mortalities during composting with bulking material comprised of swine manure and sawdust. The laboratory and field studies were conducted using mimic swine mortalities (MSM) and real swine mortalities, respectively. The sawdust to swine manure ratios of 20:80, 40:60, 70:30, and 100:0 were treatments identified as T₁, T₂, T₃, and T₄. In the laboratory study, high degradation of the mortalities (>85%) occurred in all treatments, except the T₁ treatment. The T₂ treatment obtained high degradation at a desirable level. In the field study, the degradation of the soft tissues of the mortalities in the T₂ and T₁ treatments reached 99.7 and 84.5%, respectively. The final C/N ratio of treatment T₂ (17.5) was higher than treatment T₁ (16.8). The addition of swine manure helped to develop relatively rapid temperature homogeneity between the mortality and the bulking materials, and the sawdust to swine manure ratio of 40:60 proved best for swine carcass degradation.     

Fate of enrofloxacin in swine sewage

The fate of enrofloxacin present in raw sewage at a swine-breeding facility was investigated by liquid-liquid extraction and reversed-phase liquid chromatography with photodiode array detection. Samples were collected in the storage pits of each pigsty and in a nonaerated lagoon used to stock the sewage. In the pigsties, the sewage was mixed with 10% olive oil groundwater, following a certified procedure (cod. Cer 020301) which reduces the bad odors and produces a better manure. This sewage treatment for 8 months in the lagoon dramatically reduced the amount of enrofloxacin to levels under the detection limit of 0.6 microg.L(-)(1). The results stress the importance of correct sludge management in limiting the impact of enrofloxacin in the environment.     

Amino acid analysis of feedstuff hydrolysates by cation exchange high performance liquid chromatography

Corn, peanut meal, and soybean meal samples were either untreated or oxidized with performic acid before hydrolysis; the amino acids were determined by cation exchange high performance liquid chromatography (LC) and conventional cation exchange LC using an amino acid analyzer (AAA). Reproducibility of each procedure was assessed by repeated injections of the same calibration standard solution over a period of several days. LC data were more precise with regard to coefficients of variation for amino acid retention times, but were more variable with regard to peak areas. Although some significant differences between methods were noted, feedstuff amino acid values obtained by LC and AAA compared very well. The only consistent differences observed within each feedstuff were that Phe and Tyr values were significantly lower when analyzed by LC compared with AAA. Results of this study suggest that modular LC instrumentation can be used to accurately and reproducibly analyze amino acids in feedstuff hydrolysates. Advantages of using ninhydrin derivatization for feedstuff analysis, as opposed to using o-phthalaldehyde or dansyl chloride, are discussed.     

Detection of nutrient elements and contamination by pesticides in spinach and rice samples using laser-induced breakdown spectroscopy (LIBS)

The laser-induced breakdown spectroscopy (LIBS) technique was applied to quantify nutrients (Mg, Ca, Na, and K) in spinach and rice and to discriminate pesticide-contaminated products in a rapid manner. Standard reference materials (spinach leaves and unpolished rice flour) were used to establish a relationship between LIBS intensity and the concentration of each element (Mg, Ca, Na, and K) (i.e., calibration line). The limits of detection (LODs) for Mg, Ca, Na, and K were found to be 29.63, 102.65, 36.36, and 44.46 mg/kg in spinach and 7.54, 1.76, 4.19, and 6.70 mg/kg in unpolished rice, respectively. Concentrations of those nutrient elements present in spinach and unpolished rice from a local market were determined by using the calibration lines and compared with those measured with ICP-OES, showing good agreement. The data also suggested that the LIBS technique with the chemometric method (PLS-DA) could be a great tool to distinguish pesticide-contaminated samples from pesticide-free samples in a rapid manner even though they have similar elemental compositions. Misclassification rates were found to be 0 and 2% for clean spinach and pesticide-contaminated spinach, respectively, by applying the PLS-DA model established from the training set of data to predict the classes of test samples.     

The confirmation of diethylstilbestrol residues in beff liver by gas chromatography-mass spectrometry.

A confirmatory test for the presence of the growth-promoting hormone, diethylstilbestrol (DES), in beef liver is described, Samples are subjected to a published electron capture gas chromatographic method that involves the formation and measurement of the bis-dichloroacetyl derivative of DES. The presence of the derivative is then confirmed by gas chromatography-mass spectrometry, using a repetitive scanning technique to maximize response. The isotope pattern of the tetrachlorinated molecular ion greatly facilitates the confirmation.