原子荧光法测定酱油中总砷的含量

为了研究酱油等食品中总砷的含量测定方法,采用硝酸-高氯酸混合酸作为前处理样品,再运用原子荧光光谱法测定其含量。在选定的条件下,该方法的检出限为0.062 5 ng/g(或ng/mL),在0~20 ng/mL内线性良好,相关系数R2=0.999 2,回收率为90%~100.2%,相对标准偏差1.98%。该方法较简便、灵敏度较高、精密度和准确性均较好,可以满足新食品安全标准的要求。     

液相色谱-原子荧光光谱法测定稻米中无机砷含量的不确定度评定

采用液相色谱-原子荧光光谱法测定稻米中无机砷的不确定度评定方法。建立数学模型,分析影响其不确定度的因素来源,对各不确定度分量进行评定,并计算合成不确定度,评定结果的扩展不确定度。稻米中无机砷含量的结果 0.114±0.019 mg/kg (k=2,置信水平95%)。拟合标准曲线是该方法不确定度的主要来源,其他分量影响相对很小,可以忽略不计。     

氢化物原子荧光光度法测定食品中汞含量不确定度评定

对氢化物原子荧光光度法测定食品中汞含量进行不确定度评定,建立起较完善的评定体系,探寻不确定度的主要来源,加以控制,提高检测的质量。评定结果表明:校准曲线的线性回归和测量的重复性是影响该方法的不确定度的主要因素,从而为氢化物原子荧光法测定食品中重金属的不确定度评定提供了相关基础。     

原子荧光光谱法测定米发糕中砷的测量不确定度的评定

介绍了原子荧光光谱法测定米发糕中砷的测量不确定度的评定方法,为建立有效的质量控制方法提供科学依据。确定和计算测定过程中的各不确定度分量,最后整体合成。原子荧光光谱法测定米发糕中砷的测量不确定度为0.006939mg/kg。该方法评定过程合理,步骤清晰,不重复和遗漏。     

银盐法测定稻谷中无机砷含量的不确定度评定

按GB/T5009.11-2003《食品中总砷及无机砷的测定》无机砷测定中第二法银盐法要求对稻谷中无机砷的含量进行检测,并评定了检测结果的不确定度。评定发现最终不确定度来源主要来自于标准曲线引入的不确定度和重复性实验引入的不确定度。     

对凯氏定氮法测定食品中蛋白质含量的测量不确定度评定

通过对凯氏定氮法测定食品中蛋白质含量的测量不确定度分析,对其标定结果的质量进行了定量表征。结果表明,该食品中蛋白质的含量为25.88%±0.15%(k=2),测量结果重复性的不确定度对总体不确定度作用最大。     

氧化镁中氧化钙含量测定不确定度评定

根据中华人民共和国药典2010版二部用EDTA络合滴定法检测氧化镁中的氧化钙含量。通过对测定过程中各个不确定度分量的评定,计算出测定过程中的不确定度,并评估了合成标准不确定度和扩展不确定度。该不确定度评价方法对EDTA滴定法检测氧化镁中的氧化钙含量的测定分析工作中有较强实用价值。     

原子吸收光谱法测定水中铅含量的不确定度评定

探讨了原子吸收法测定水中铅含量的不确定度,根据测定不确定度的数学模型计算分析出测定过程曲线拟合所引起的不确定度为不确定度的主要来源。     

凯氏定氮法测定豆粕中蛋白质的不确定度评定

粗蛋白是评定饲料原料及其产品的重要指标之一,在理化分析中,测定结果存在不确定度。找出影响测量不确定度的因素,对各个不确定度分量进行评估和计算合成,并最终得出豆粕中蛋白质含量的合成标准不确定度和扩展不确定度。分析了不确定度的来源,提出减小不确定度的方法。     

配制酒氰化物含量的不确定度评定

依照GB 5009.36—2016食品中氰化物的测定,采用分光光度法测定配制酒中氰化物含量。为了准确测定配制酒中氰化物含量,对拐枣酒氰化物的不确定度进行评定,评定过程中的不确定度分量主要来源包括测量的重复性、试样量取体积、定容体积、标准溶液浓度、标准曲线拟合和酒精度折算。经评定配制酒(拐枣酒)中氰化物的不确定度结果为X=2.0±0.02 mg/L;k=2,则扩展不确定度U=0.02 mg/L。     

气相色谱（GC）测定蔬菜中拟除虫菊酯类农药残留量

对气相色谱（GC）测定蔬菜中拟除虫菊酯类农药残留量的不确定度进行分析评估。通过建立的数学模型和推导出不确定度的计算公式,分析了测量过程的不确定度来源,并对不确定度的各个分量进行计算,最后评估了标准合成不确定度和扩展不确定度。     

Evaluation of chlorophyll fluorescence as a tool for the identification of drought tolerance in upland cotton

Chlorophyll fluorescence (CF) is one tool used by researchers to quantify plant water status during periods of limited water availability. The research reported herein was designed to evaluate a CF-based protocol as a tool for use in cotton, Gossypium spp. breeding programs for the identification of drought tolerant genotypes. Twenty genotypes were selected to represent diverse and distinct US germplasm pools. Replicated tests were performed in Lubbock and College Station, TX in 2006 and 2007. Dryland and irrigated treatments, as main plots, were applied in a randomized complete block design, split to genotypes. CF measurements were taken at mid-bloom and late bloom growth stages. Source leaf tissue was harvested at predawn and subjected to high temperature incubation with CF measurements subsequently taken hourly for 5 h. Drought stressed plants had not mobilized their carbohydrate reserves from their source leaves overnight and thus maintained cell viability and therefore higher CF values throughout the incubation and measurement period with the opposite being true for non-stressed plants. Fiber lint yield and fiber properties were measured for comparison with the CF data. Genotype × treatment effects complicated the classification of genotypic response to drought. Few and inconsistent correlations were found among CF values and lint yield or fiber properties. Data suggested that this procedure provides little potential in selecting plants for drought tolerance when plants are grown under field culture.     

氢化物原子荧光光谱法测定稻米中硒含量的不确定度研究

依据JJF 1059.1-2012《测量不确定度评定与表示》,建立不确定度的数学模型,系统地分析计算氢化物原子荧光光谱法测定稻米中硒含量的不确定度。结果表明,氢化物原子荧光光谱法测定稻米中硒含量的不确定度主要来源于:重复性引入的不确定度、斜率和截距引入的不确定度及工作曲线拟合引入的不确定度。由本试验方法得到的稻米中硒含量扩展不确定度及最终结果表示为(0.027 9±0.004 0)mg/kg(k=2)。     

福建省规模化猪场饲料和猪粪中重金属砷含量测定初报

采用氢化物原子荧光光度法和电感耦合等离子体质谱法(ICP-MS)对福建省不同地区56个不同规模养猪场的104份饲料与56份猪粪中重金属砷(As)的含量进行了测定和分析。结果表明：104份饲料中有12份样品检测As含量超标（大于2 mg?kg-1）,超标率为11.54%,其中以漳州地区猪场饲料中As污染最为严重;不同规模猪场饲料和不同类型的饲料中As含量的超标率也存在差异,其中以小规模猪场饲料和小猪料的As含量超标最为严重,分别为13.79%和17.39%。在12份饲料超标样品中,有9份使用省外添加剂来源配制饲料,省外添加剂来源配制饲料As含量超标率为21.59%（9/41）。56份猪粪仅在龙岩一处中规模猪场检测超标（102.4mg?kg-1>30mg?kg-1）,超标率仅为1.79%。     

Magnetic field effect on the fluorescence properties of two metal(II) complexes based on 1,3,5-triazine-2,4,6-triyltrithio-tri-acetate

Two metal (Ⅱ) complexes based on 1,3,5-triazine-2,4,6-triyltrithio-tri-acetate exhibit similar (6,3)-connected 2D layer with kgd topology. Negative and positive magnetic field effects (MFEs) on the fluorescence properties of the Mn(Ⅱ) and Zn(Ⅱ) complexes are observed, respectively.     

NaCl胁迫对2个网纹甜瓜幼苗生长量及叶绿素荧光参数特性的影响

摘要：本试验比较了两个网纹甜瓜（‘春丽’和‘阿鲁斯春’）幼苗在不同浓度NaCl（0、50、100、150和200 mmol?L-1）胁迫下幼苗生长量、叶绿素含量和叶绿素荧光参数的变化。结果表明: 低浓度NaCl(50 mmol/ L)处理后,两个甜瓜幼苗的生长量、Fv/Fm、ETR、ФPSⅡ和qP值与对照比有所上升,随着盐浓度的增加,这些指标开始下降。相同浓度的NaCl处理对‘春丽’幼苗生长和叶绿素荧光参数的变化影响小于‘阿鲁斯春’。在0-200mmol?L-1NaCl胁迫下‘春丽’Pc平均值比“阿鲁斯春”高,Hd所占比例低于‘阿鲁斯春’,两个品种Ex平均值比较接近,这些数值的变化与甜瓜品种的耐盐性有关。     

Karyotype analysis and physical mapping of 45S rRNA genes in Hydrangea species by fluorescence in situ hybridization

Detailed karyotypes of Hydrangea macrophylla, Hydrangea paniculata and Hydrangea quercifolia were constructed on the basis of arm lengths and centromeric index, together with 45S rDNA fluorescence in situ hybridization. Although the chromosomes were small, they were well distinguishable for all species. Chromosome morphology and karyotypes were different for the three species. H. macrophylla had six metacentric (M), eight submetacentric (SM) and four subtelocentric (ST) chromosomes. The karyotype of H. paniculata contained seven M, 10 SM and one ST chromosomes and H. quercifolia had six M, 10 SM and two ST chromosomes. The variability among three species also was expressed by 45S rDNA signals. H. macrophylla had a nucleolar organizing region on chromosome 2, H. paniculata had 45S rDNA signals on chromosomes 2, 5 and 11 and H. quercifolia on chromosomes 3 and 8. Hybridization signal always was distally on the short arm but the strength of the signals was different for the three species. The chromosome portraits made in this study will be used to trace chromosome behaviour in interspecific hybrids resulting from breeding work between the three species.     

荧光假单胞菌工程菌株的构建及对黄瓜枯萎病的防治效果

采用基因工程的方法,将含有2,4-DAPG基因的质粒pMON5122导入到野生型荧光假单胞菌株中,探索了不同热激时间、不同CaCl2浓度和荧光假单胞菌的不同生长时期对转化子形成的影响;研究了荧光假单胞菌工程菌株对黄瓜枯萎病的防治效果。结果表明,荧光假单胞菌生长到OD约0．53时,用0．025mol／L CaCl2处理细胞,热激3～4min,转化频率最高;荧光假单胞工程菌株对黄瓜枯萎病的盆栽防治效果达到75．0％,并且能够提高黄瓜出苗率。