QuEChERS法-液相色谱-串联质谱法测定蔬菜中7种农药及其代谢物的残留量

样品经乙腈提取,C_(18)吸附剂和石墨化碳黑分散固相萃取净化,液相色谱-三重四极杆串联质谱在动态多反应监测模式下检测,基质匹配标准曲线外标法进行定量,建立了蔬菜中7种农药及其代谢物的多残留分析方法。在10、20μg/kg 7种农药及其添加物添加水平下,农药及其代谢物的平均回收率为71.9%~117.8%,相对标准偏差为0.8%~9.6%,定量限为0.2~10μg/kg。该方法简便、快速、灵敏,适用于蔬菜中多种农药及其代谢物的同时检测。     

气相色谱-质谱法分析冷鲜滩羊肉微生物差异代谢物

以托盘密封包装的冷鲜滩羊肉为研究对象,基于气相色谱-质谱平台对其中微生物的代谢物组进行检测,区分不同贮藏时间生物样本之间的差异,寻找出造成上述差异的变量或分子,并将该差异物映射到滩羊肉主要腐败菌假单胞菌属(Pseudomonas)相应的代谢途径中,分析其代谢的相对强度。采用模式识别方式正交偏最小二乘法判别分析将不同贮藏时间组完全区分。结果表明:该差异代谢物所映射的代谢途径中三羧酸循环、精氨酸代谢、丙氨酸、天冬氨酸及谷氨酸代谢及磷酸戊糖途径的代谢强度相对较高。说明基于气相色谱-质谱技术对微生物的代谢物组进行检测,寻找并鉴定差异代谢物是可行的。     

Subjective wear trials to evaluate thermal comfort of the foot clothing system including a sweat pad

Subjective wear trials were conducted to evaluate effects of disposable antibacterial sweat pads on foot thermal comfort. Sweat pads were produced with polypropylene and polylactic acid nonwoven topsheet layers which were treated with different herbal antibacterial materials. Trials were carried out with 10 male subjects under 10 °C and 50% relative humidity simulating sweating during a moderate activity in cold environments. Besides microclimate temperature and relative humidity measurements, subjective thermal (coolness, dampness, and comfort) and other sensations (stickiness, slippiness, etc.) were obtained by five point rating scales. Bending rigidity, friction coefficients, and moisture management properties of the topsheet fabrics and pads were tested. Results show that foot sweat pads enabled drier microclimate, warmer sensations, and higher comfort evaluations. Antibacterial treatments did not affect bending rigidity values of the nonwoven topsheet fabrics, but some applications decreased spreading speed, increased roughness of the pad surfaces, and wetting time values which are not preferable.     

浓香型白酒窖泥梭菌的分离及其挥发性代谢产物分析

从河南张弓老酒酒业的窖泥中分离厌氧梭菌属细菌,基于微生物16S rRNA基因序列分析对分离到的细菌进行鉴定;采用顶空固相微萃取（HS-SPME）和气相色谱-质谱联用（GC-MS）技术萃取和检测了分离菌株发酵液中的挥发性代谢产物。结果表明,分离到的88株细菌与基因库中8种芽孢梭菌（Clostridium celerecrescens、C. cochlearium、C. carboxidivorans、C. sporogenes、C. sartagoforme、C. thermopalmarium、C. aurantibutyricum和C. butyricum）具有较高的序列同源性。从分离菌株的发酵液中共检测到20种酯类、12种酸类、11种醇类和4种醛类物质,还有一部分酮类和醚类物质;其中主要的酯类物质有丁酸乙酯、丁酸丁酯、3-苯丙酸乙酯等,酸类物质主要为丁酸和己酸,醇类物质主要为丁醇、己醇和3-苯丙醇。本研究有助于进一步揭示窖泥中可培养梭菌菌群对浓香型白酒风味的贡献。     

菌株Sr18杀线虫代谢物的规模发酵及杀线效果研究

实验以菌株Sr18（Syncephalastrum racemosum）为发酵对象,以杀线虫活性为考察指标,在5 L、30 L发酵研究基础上,进行了200 L和5 t发酵罐水平上的规模发酵实验。结果显示,200 L罐发酵工艺参数为接种量4%,发酵温度26 ℃,罐压0.05～0.12 MPa,空气流量4～9 m3/h,转速120～198 r/min,发酵周期48 h;5 t罐发酵参数为接种量4%,发酵温度26 ℃,罐压0.03 MPa,空气流量65～80 m3/h,转速80～90 r/min,发酵周期40 h。在此发酵条件下,200 L和5 t罐的1倍稀释发酵液的杀线虫活性均可达到100%,表明实验所设定的发酵参数适用、可控。     

Effect of inhibiting the lactogenic signal at calving on milk production and metabolic and immune perturbations in dairy cows

During the periparturient period, the abrupt increase in energy demand for milk production often induces metabolic and immunological disturbances in dairy cows. Our previous work has shown that reducing milk output by milking once a day or incompletely in the first few days of lactation reduces these disturbances. The aim of this study was to reduce metabolic and immunological disturbances by limiting milk production during the first week of lactation by inhibiting the lactogenic signal driven by prolactin. Twenty-two fresh cows received 8 i.m. injections of the prolactin-release inhibitor quinagolide (QUIN; 2 mg) or water as a control (CTL). The first injection was given just after calving, and the subsequent 7 injections were given every 12 h. Milk production was measured until d 28 after calving. Blood samples were taken from d 1 (calving) to d 5 and then on d 7, 10, 14, 21, and 28 to measure concentrations of urea, phosphorus, calcium, glucose, nonesterified fatty acids (NEFA), β-hydroxybutyrate, and prolactin. Other blood samples were taken on d 2, 5, 10, and 28 to analyze oxidative burst, phagocytosis, and the effect of the serum on the lymphoproliferation of peripheral blood mononuclear cells from donor cows. Blood prolactin concentration was lower from d 2 to 5 but higher from d 10 to 28 in the QUIN cows than in the CTL cows. Milk production was lower from d 2 to 6 in the QUIN cows than in the CTL cows (24.3 ± 6.4 and 34.8 ± 4.1 kg/d on average, respectively). We observed no residual effect of quinagolide on milk production after d 6. During the first week of lactation, blood glucose and calcium concentrations were higher and β-hydroxybutyrate concentration was lower in the QUIN cows than in the CTL cows. Blood NEFA, urea, and phosphorus concentrations were not affected by the treatment. At d 2 and 5, the phagocytosis ability of polymorphonuclear leukocytes was not affected by treatment; however, quinagolide injection enhanced the proportion of cells that entered oxidative burst, The mitogen-induced proliferation of peripheral blood mononuclear cells was greater when they were incubated with serum harvested from the CTL cows and was negatively correlated with the NEFA concentration in the serum. Reducing the prolactin peak at calving was effective in reducing milk production during the first week of lactation without compromising the dairy cow's overall productivity. Slowing the increase in milk production allowed a more gradual transition from pregnancy to lactation and led to a reduction in metabolic stress and an improvement in some immune system aspects during this period.     

HPLC-MS/MS测定玉米中异恶唑草酮及代谢物残留量

建立玉米中异恶唑草酮及代谢物残留量同时测定的高效液相色谱-串联质谱(high performance liquid chromatorgerphy-mass spectrometry/mass spectrometry,HPLC-MS/MS)分析法。试样用乙酸-乙腈(1:99, V/V)高速匀浆提取、醋酸钠和无水硫酸镁盐析后,提取液经N-丙基乙二胺(PSA)、十八烷基硅烷(ODS)和石墨化炭黑(GCB)净化,除去样品中脂肪和色素等大多数的干扰基质,用高效液相色谱-串联质谱仪检测,外标法定量。异恶唑草酮及代谢物的添加量在0.005～0.100mg/kg范围内,样品平均加标回收率在74.8%～107.2%之间,相对标准偏差为6.45%～11.15%;方法的检测限异恶唑草酮为0.01mg/kg、异恶唑草酮代谢物0.005mg/kg。本方法灵敏、准确、省时和操作简便,适用于玉米中异恶唑草酮及代谢物残留量同时检测和确证。     

链霉菌 CSDX076次级代谢产物Pseurotin A的分离及结构鉴定

对从赤水丹霞山土壤样品中分离得到的链霉菌(Streptomyces sp.)CSDX076进行液体发酵。利用乙酸乙酯萃取,硅胶柱层析、薄层层析和反相中压柱层析对发酵液中的次级代谢产物进行分离、纯化;通过核磁共振法对纯化的分离产物进行结构鉴定。结果表明,该研究从链霉菌属中成功分离得到次级代谢产物Pseurotin A。采用滤纸片法对Pseurotin A进行抗菌活性测试,Pseurotin A对金黄色葡萄球菌具有抑制作用,其抑菌圈直径为5.0 mm。