采用计算机视觉进行孵化鸡蛋成活可能性的自动检测

本研究将计算机视觉技术与遗传神经网络相结合,建立一套适合于孵化鸡蛋可成活性自动检测的计算机视觉系统,通过计算机视觉技术获取了孵化鸡蛋的角度直方图,并提取了孵化鸡蛋表面颜色特征,采用遗传算法优化了多层前馈神经网络的拓扑结构与权值,提高了神经网络的学习质量和学习速度,实现了孵化鸡蛋可成活性的自动检测,实验结果表明,该方法准确率较高,并具有鲁棒性和高速度。     

Determination of pyrethroids in chicken egg samples: development and validation of a confirmatory analytical method by gas chromatography/mass spectrometry

The aim of this study was to develop and validate an efficient analytical method based on gas chromatography/tandem mass spectrometry (GC/MS/MS) for detection and quantification of six pyrethroids residues (Phenothrin, Permethrin, Cyfluthrin, Cypermethrin, Deltamethrin and Fenvalerate) in chicken eggs. The method was based on a preliminary liquid–liquid extraction of albumen‐free yolk samples, followed by a clean‐up by solid‐phase extraction. GC/MS/MS analyses were carried out in the selected reaction monitoring mode. Validation parameters such as specificity, detection capability, decision limit, precision, recovery, stability and ruggedness were determined, resulting in compliance with Decision 2002/657/EC. No complicated apparatus are required; moreover, low volumes of organic solvents and a nonintensive manual labour are required. These low costs and simple procedure, based on rapid and safe operations, may represent a useful tool in the routine analysis of pyrethroids pesticides, in the place of the currently used conventional techniques.     

HS-SPME结合GC-MS分析煎鸡蛋的挥发性风味成分

采用顶空固相微萃取与GC-MS联用方法对煎鸡蛋中挥发性成分进行提取与分析,考察萃取头、萃取温度和吸附时间对分析结果的影响,得到优化的顶空固相微萃取条件为:黑色萃取头(75μm Carboxen/PDMS),吸附温度75℃,吸附时间70 min。在优化的条件下分析,共鉴定出50种挥发性风味成分,其中,醛类16种(40.588%)、含氮化合物14种(23.639%)、醇类8种(7.156%)、烃类3种(4.800%)、酚类及杂环化合物3种(1.755%)、酮类3种(0.868%)及含硫化合物3种(0.563%)。鉴定出含量较高(相对质量分数大于2.5%)的物质有:2,5-二甲基吡嗪、3-甲基丁醛、2-甲基吡嗪、壬醛、苯甲醛、反,反-2,4-癸二烯醛、辛醛、2-甲基丁醛、反-2-癸烯醛、3,7-二甲基-1,6-辛二烯、1-辛烯-3-醇。     

Survival of tapeworm eggs, free and in proglottids, during simulated sewage treatment processes

The survival of T. saginata eggs in stored sludge, anaerobic and aerobic mesophilic and thermophilic digesters is examined, particularly with reference to the protection afforded to eggs bound within proglottids. Gross survival times paralleled the results of other workers. However, proglottid bound eggs always survived for longer periods than did freshly dissected eggs. The consequences of this for experimentation is discussed. T. saginata eggs were killed in all treatments with anaerobic digestion being more effective than aerobic digestion and lagooning. In all processes the major controlling factor was temperature; at 35°C eggs were killed faster than at 20°C, eggs at 55°C survived for only a few hours whether free or in proglottids.     

鸡蛋中药物残留加工因子与监测结果分析

目的分析鸡蛋中药物残留膳食暴露加工因子的确定与监测样品结果。方法按监测计划采集样品并制备模拟样品,应用超高压液相色谱-串联质谱测定15种药物残留含量,并计算加工因子与去除率。结果120份样品检出氧氟沙星5份(2.5～65.8μg/kg),环丙沙星1份(2.4μg/kg)。煮蛋器15 min加工因子为0.10～0.87,微波加热(60s)加工因子为0.10～0.92。结论加工处理过程能显著降低食物中药物残留量,降低人群膳食暴露风险,蒸蛋器加热与微波烹调2种加工处理方式相比较,微波烹调过程对药物残留的去除作用小。监测结果分析表明,在不同地区、不同品种和不同参数间的药物残留检出率无统计学差异。     

UPLC-MS/MS检测鸡蛋中22种喹诺酮类药物残留方法的研究

应用超高效液相色谱串联质谱建立鸡蛋中加雷沙星、曲伐沙星、莫西沙星、奥比沙星、吉米沙星、加替沙星、培氟沙星和环丙沙星等22种喹诺酮类药物残留检测方法。样品经过2%甲酸乙腈提取、正己烷分步去脂,Oasis HLB柱净化后,经Acquity UPLC BEH Shield RP18(100 mm×2.1 mm,1.7μm)分离,以甲醇和0.1%甲酸水溶液为流动相进行梯度洗脱,双通道MRM信号采集模式,22种喹诺酮类药物能在11 min完好分离,方法的最低定量限均低于1.0μg/kg,在2.0~100.0μg/L浓度范围内,22种喹诺酮类药物线性良好,相关系数均在0.99以上;通过2、10、20 g/kg三个浓度的加标回收实验表明,回收率为60.1%~96.2%,RSD%值为1.44%~11.1%。该方法相比现有国标检测药物种类多,新型药物多,对更全面筛查和确证鸡蛋中喹诺酮类药物残留,防范非法添加造成安全隐患具有一定的参考价值。     

紫外-可见分光光度法快速检测蛋黄中苏丹红Ⅳ的研究

采用紫外一可见分光光度计对新鲜鸭蛋蛋黄的石油醚一丙酮的提取液进行光谱扫描,建立了纯蛋黄液、标准苏丹红Ⅳ样品以及含有苏丹红Ⅳ的蛋黄液的光谱扫描曲线.通过对光谱扫描曲线的相似度比较及对光谱扫描原始曲线图的数学处理,分别运用波长差和一级微分两种方法,快速检测出新鲜鸭蛋黄中苏丹红Ⅳ.实验结果表明.波长差法的回收率高于一次微分法,而且数值分布相对集中,在对被检测样品中的苏丹红Ⅳ的定量上的精确性和稳定性优于一次微分法,而一次微分法则可直观对苏丹红Ⅳ定性.运用波长差法计算样品RSD(%),得备检样品加标苏丹红Ⅳ 2μg/mL的RSD(%)为14.2,平均回收率为106.01%,加标4μg/mL的RSD(%)为9.4,平均回收率为105.68%;运用一次微分法进行计算,得备检样品加标苏丹红Ⅳ 2μg/mL的RSD(%)为10.41,平均回收率为82.46%,加标4μg/mL的RSD(%)为6.73,平均回收率为94.21%.数据表明样品中加标苏丹红Ⅳ浓度越大.该方法对样品检测的稳定性越好.     

Spatial and temporal distribution of ichthyoplankton during an unusual period of low flow in a tributary of the São Francisco River,Brazil

Flow‐dependent fish specialists require specific conditions for reproduction, so the success and reproductive intensity of these animals are determined by the flood regime. Thus, this study investigated the spatial and temporal reproductive patterns of fish, especially migratory Prochilodus species (flow‐dependent specialists) in an unusual period of low flow in the Pará River sub‐basin, one of the main tributaries of the upper São Francisco River. For this, ichthyoplankton collections were carried out between November 2013 and February 2014. Data were analysed considering the spatial and temporal variations in density of eggs and larvae for the upper, middle, and lower portions of the Pará River sub‐basin, and correlating this to some environmental variables. The results showed that the small headwater stretch of the Pará River is one relevant spawning area for migratory fish species. However, this area is isolated by the Cajuru reservoir, which makes it uncertain the recruitment of these embryos, due to interruption of natural drift between spawning/nursery areas caused for reservoirs. Larvae of newly hatched migratory species found in tributaries of the lower Pará River sub‐basin also indicate these species use these tributaries as spawning grounds and migratory routes. The period in which the research was conducted represented the most atypical low flow, one in the last 75 years, resulting in the low variability in the environmental parameters. Although few parameters increased briefly in this low flow period influenced by greater rainfall in December, this precipitation was possibly responsible for the final gonadal maturation and spawning of migratory species.