Distribution pattern of eight heavy metals in the outer and inner tissues of ten commonly used vegetables

This study reports the distribution of eight heavy metals (Cd, Co, Cr, Cu, Hg, Mn, Ni, and Pb) in the outer and inner tissues of ten different vegetables from the Qassim region of Saudi Arabia. The oven-dried (65°C, 48 h) vegetable samples were subjected to microwave acid digestion before heavy metals analysis using inductively coupled plasma optical emission spectrometry. The results showed that Co, Cd, and Pb were absent in the outer tissues of all the vegetables, whereas these elements were detected in the inner tissues of some vegetables in the ranges of 0.01–0.23 mg/kg wet weight, 0.03–0.42 mg/kg, and 0.02–3.44 mg/kg, respectively. The traces of Hg (1.83–3.59 μg/kg) were noticed in the outer tissues of all the samples; however, it was not detected in the inner tissues of vegetables. The variable distribution of heavy metals in different vegetables is influenced by several factors, including exposure route, physicochemical properties of heavy metals, species of crops, cultivation strategy, soil type, and growing conditions. In conclusion, although the representative samples of vegetables used in this study contained safe levels of Cd, Co, Ni, and Pb, higher than recommended upper limits of Cr, Cu, and Mn were observed in some vegetables. These findings suggested that regular monitoring of heavy metals in vegetables is important to safeguard consumers.     

气相色谱法测定猪肉、鱼和虾中三甲胺的含量

采用气相色谱法,对猪肉、鱼和虾肉的三甲胺含量进行测定并寻找了最佳测定条件。测得峰面积与三甲胺浓度在0－25μg/ml范围内呈良好的线性关系（γ=0.9999,n=6),相对标准偏差为3．1％－5．9％,回收率为95．0％－97．7％,且该法操作简便,快速,准确。     

用于牙硬组织的弥补物材料

生物活性陶瓷或玻璃取代物和生物可降解的有机材料是人工制造的,可以转换成一定形状作为牙硬组织的弥补物,此时嵌进一个生物金属或其他生物材料支撑,是生物相容性的。并被认为有极好的力学性质,对矫形学或牙修补物是有用的。     

超高效液相色谱-串联质谱法测定动物源性食品中硝基呋喃代谢物

目的建立动物源性食品中四种硝基呋喃代谢物的超高效液相色谱串联质谱(ultra pressure liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)的快速检测方法。方法样品经盐酸溶液水解,邻硝基苯甲醛(2-NBA)37℃衍生16 h后,调节衍生液的pH=7.6,用乙酸乙酯提取。分析物采用电喷雾电离,正离子扫描,多反应检测模式(MRM),基质匹配内标标准曲线法定量。结果四种代谢物的工作曲线在0.1～10.0μg/L浓度范围内线性良好,相关系数R2均达到了0.995以上,氨基脲(SEM或SCA)与1-氨基-乙内酰脲(AHD)最低检出限均为0.1μg/kg,5-吗啉甲基-3-氨基-2-恶唑烷基酮(AMOZ)与3-氨基-2-恶唑烷基酮(AOZ)最低检出限均为0.05μg/kg。平均回收率在91.8%～107.0%之间,相对标准偏差均小于10%。结论样品前处理简单、测定时间短、灵敏度高,适用于猪肉、牛肉、鸡肉、猪肝和水产品(鱼类及虾类)中硝基呋喃类代谢物残留的快速测定。     

Changes in texture, colour and fatty acid composition of male and female pig shoulder fat due to different dietary fat sources

Two experiments with 72 slaughter pigs in each were conducted. Entire males and females were individually fed restricted. Palm kernel-, soybean- and fish-oil were used in varying combinations, giving different dietary fat levels (29-80 g/kg) and iodine values ranging from 50 to 131. Shoulder fat was analysed for fatty acid composition (inner and outer layer), firmness and colour. A clear dose-response relationship was seen between fatty acids in diets and in shoulder fat. Interestingly, the very long chain n-3 fatty acids seemed to be deposited more efficiently when additional fat was included in the diet. Both high and low dietary iodine values changed towards less extreme iodine values in fat. Low-fat diets enhanced de novo synthesis of fatty acids. Males revealed a higher percentage of PUFA and a lower percentage of C18:1 and MUFA. Fat firmness, but not colour, was influenced by sex and dietary fat source.     

金黄色葡萄球菌ST398-t571型在陕西生猪屠宰场的流行传播及其耐药性分析

目的 调查陕西省某生猪屠宰场ST398-t571型金黄色葡萄球菌的流行情况及耐药性。方法 本研究对陕西省某生猪屠宰链及屠宰场内部环境共采集485份样品。使用常规检测方法和分子生物学技术对金黄色葡萄球菌进行分离鉴定,然后对分离株进行分子分型鉴定和对15种抗菌药物进行耐药性试验;并对其进行26种毒力基因和13种耐药基因的检测。结果 样品中共分离出62株金黄色葡萄球菌,总分离率为12.8%;其中ST398-t571型分离株为优势克隆型,占90.3%(56/62)。耐药试验结果显示,所有受试菌株均对苯唑西林、阿米卡星、万古霉素和头孢噻肟敏感,对其余的抗菌药物表现出不同程度的耐药性。26种毒力基因中11种毒力基因(seb、seg、sei、sek、sen、seq、lukD、lukE、lukF-PV、lukS-PV、sasG)被检出。13种被检耐药基因除万古霉素耐药基因vanA基因外均有检出。结论 屠宰场生猪屠宰链普遍存在以ST398-t571型为主的金黄色葡萄球菌污染,不同批次分离株基因携带情况存在一定差异且菌株存在较为严重的耐药性。     

基于ICMP协议的指纹探测技术研究

准确地获取计算机网络中远程主机的操作系统类型及其版本号是研究计算机网络安全漏洞的一个重要内容,因为大多数的安全漏洞都是和一定的操作系统相联系的。指纹是指能够通过网络连接获取的唯一标识某一具体操作系统的类型及其版本号的一组特征信息的集合。作为指纹的特征信息集必须满足完备性和唯一性的要求。所谓指纹探测技术,就是根据不同类型、不同版本的操作系统在协议栈实现上的细微区别,通过向目标系统发送特定格式的数据包,并从反馈数据包中提取操作系统指纹信息的远程操作系统探测技术。     

高磷生铁脱磷试验

 在实验室高温箱式炉的条件下,以CaO-Fe2O3-CaF2为主要的渣系,对脱磷剂的配比、加入量、熔化温度、碱度进行试验研究。试验结果表明,温度为1450℃的条件下,w（CaO）/w（Fe2O3）= 2.5,碱度为2.5,脱磷剂加入量为12%,并加入一定量的助熔剂,从而使生铁磷质量分数由原来的1.02%降低到0.47%。最后,调整脱磷剂的用量,得出脱磷剂的最佳配比。