微波溶样原子荧光法测定化探样品中的砷、锑、铋和汞

采用微波消解样品预处理技术和原子荧光光谱法,测定了化探样品中砷、锑、铋和汞的含量.建立了最佳微波消解程序,最终确定了4种元素连续测定的最佳实验条件;可以一次溶解样品,在同一仪器上用基本相同的工作条件同时测定砷、锑、铋和汞,RSD＜3.82%.该方法适用于化探样品中w(As) =(0.5～100)×10-6、w(Sb)=(0.05～10)×10-6、w(Bi)=(0.05～5)×10-6和w(Hg)=(0.005～5)×10-6的连续测定.     

燃烧-中和滴定法连续测定锌精矿、锌焙砂等物料中的硫

提出了燃烧-中和滴定法连续测定锌精矿、锌焙砂等物料中的硫.该法最大优点是加一次吸收液可以连续测定20～30个样品,省去了每测定一个样品都必须拆装洗涤吸收瓶的麻烦.在硫含量为0.1%～35%的范围内,该方法的准确度和精密度令人满意.     

X-射线荧光光谱法测定硅石中硅铝铁钙钛

用国家标准物质和SiO2基准试剂配制出一系列适当含量范围的标准样品,选取适合的熔剂稀释比例,建立了熔融制样X-射线荧光光谱法测定硅石中SiO2、Al2O3、Fe2O3、CaO、TiO2的方法.对同一硅石样品进行测定,结果的相对标准偏差小于3.0％(n=12),对不同硅石标准样品进行测定,测定结果与标准值相吻合.该方法操作简单、快速,结果准确,精密度好,具有良好的实用性.     

波长色散X射线荧光光谱法测定津巴布韦化探样品中多组分

X射线荧光光谱测定化探样品中的多种元素已成为一种成熟的分析方法,适用于一般岩石、土壤和水系沉积物中主、次和痕量元素的测定。在测定津巴布韦1∶250 000化探样品中的多种组分时,由于样品为基性或超级基性岩,因此样品中Cr的质量分数异常,达到了0.x%～x%,同时发现Cr含量异常的样品中Mn的测定结果为负值。为解决津巴布韦异常化探样品的测定,将2个超基性岩标准物质(GBW07101、GBW07102)及按一定比例配制的校准物质加入校准曲线,拓展了Ni、MgO、Cr的线性范围;同时采用LiF220晶体、MnKα测定Mn,或采用LiF200晶体、MnKβ线测定Mn,消除了CrKβ线对MnKα测定的干扰,进而解决了由于Cr含量异常导致Mn测定结果为负值的难题。采用经验系数法校正基体效应,方法应用于津巴布韦样品中多组分的测定,测定结果与湿法相符,相对标准偏差(RSD,n=10)在5%以下。     

金试剂一磷酸三丁酯液珠萃取比色法测定化探样品中金

本文采用泡沫塑料富集分离金,拟定了金试剂—磷酸三丁酯液珠萃取比色测定化探样品中金的新方法.方法简单快速、灵敏度高,测定范围为0.5～5000ppb (称样15g).经样品验证结果满意.     

无舒茨试剂测定钛中氢

应用ELTRAOH900氧氢测定仪,高纯N2作载气,测定钛中氢含量,对是否需要舒茨试剂对样品气中CO净化并使用碱石棉去除进行了实验研究.结果表明,样品气中CO净化和不净化两种条件下测定钛参比物质中氢含量的测定值相对误差(准确度)几乎相同.证明样品气中CO不会干扰氢的测定,无需舒茨试剂净化样品气.     

等离子光谱法测定稀土矿石中钍

研究了用等离子发射光谱技术测定稀土矿石中钍的含量,采用碱熔法分解样品,在283.2nm,283.7nm处测定样品,分析范围0.01%～1.00%,RSD＜4%.对不同含量标准样品,经与等离子质谱法对照,结果令人满意.     

原子荧光光谱法测定地质矿物样品中痕量金属元素研究

痕量金属元素广泛分布于矿物中,长期接触会对人体产生危害,研究原子荧光光谱法测定地质矿物样品中痕量金属元素.准备主要仪器设备与试剂,配置标准溶液,设定原子荧光光谱仪工作条件,通过无机离子萃取方法,处理样品,完成测定.经实验结果分析,本文方法测定痕量元素镉的结果准确度较高,适用于地质矿物样品的测定.     

酸溶法则定氟碳铈矿-独居石精矿中混合稀土总量

我国稀土元素分析时测定常量混合稀土总量,仍然离不开传统的化学分析,其中矿样中混合稀土氧化物总量的测定也显得特别重要,长期以来样品的前处理是采用碱熔法,费时、费力、还常因高温熔融过程中样品溅出使检测结果偏低.基于此,本法采用了酸溶法处理样品,大大缩短了工时.经实验证明检测结果准确可靠,重现性较好.     

火焰原子吸收光谱法测定牛奶中锌含量的研究

[目的]为牛乳中微量元素营养价值的研究提供参考.[方法]采用稀释法处理纯牛奶样品,并采用火焰原子分光光度法测定了纯牛奶中锌元素的含量.[结果]纯牛奶中锌元素的含量为6.25 g/ml.该方法的加标回收率为104.0%,精密度(样品相对标准偏差RSD)为0.61%.[结论]该法样品前处理简便、快捷,测定结果准确,适用于纯牛奶中锌含量的测定.     

Ceranapril and cerebral blood flow autoregulation

In order to investigate the levels of the polycyclic aromatic hydrocarbons, mainly benzo[a]pyrene because of its carcinogenicity, 55 samples of smoke flavour and smoked foods were analysed. The samples tested included 11 samples of liquid smoke flavour and 44 samples of smoked foods like bacon, loin, turkey, sausage, ox rib, etc. from different brands. A liquid chromatographic method was developed using a fluorescence detector. Benzo[a]pyrene was found in 73% of the liquid smoke flavour samples analysed. The levels varied from 0.1 to 336.6 micrograms/kg. Three liquid smoke flavour samples showed levels of benzo[a]pyrene above the maximum level recommended by FAO/WHO (10 micrograms/kg). From the total of 44 smoked food samples analysed, benzo(a)pyrene was detected in 23 samples (52%). The levels varied from 0.1 to 5.9 micrograms/kg. Anthracene and fluoranthene, non-carcinogenic polycyclic aromatic hydrocarbons, were found in almost all the samples analysed. Benzo[ghi]perylene, 3,4-benzofluoranthene and 1,2,3,4-dibenzopyrene were not found in any of the 55 samples analysed.     

Recovery of Staphylococcus aureus from centrifuged quarter milk samples

The identification of cows that are positive for mastitis caused by Staphylococcus aureus is difficult under field conditions. The frequency of isolation of S. aureus from quarter milk samples was compared with the frequency of recovery of S. aureus from sediment after centrifugation of those same samples. Overall, 776 quarter milk samples from 194 cows were studied. Cultures that were positive for S. aureus were obtained from 82 samples; 153 sediments from quarter milk samples were also positive for S. aureus. The results of this investigation showed that cultures of the sediment of quarter milk samples increased the number of positive outcomes up to 145.5%, depending on the herd. Using a different group of samples, including samples taken 1 to 5 d or 7 to 10 d after calving and samples taken after intramammary therapy, a 94% increase in cultures that were positive for S. aureus after centrifugation was found compared with cultures of the same quarter milk samples that were not centrifuged. Sedimented cultures may be useful in S. aureus control programs that require the segregation, selective treatment, or culling of cows that are positive for S. aureus.     

Evidence for common coding in many-to-one matching: Retention, intertrial interference, and transfer.

Two experiments indicated that pigeons commonly code samples associated with same comparison in many-to-one matching. Experiment 1 showed that retention was similar for pigeons matching four sample stimuli (two hues and two lines) to a different pair of comparisons (hues or lines). Accuracy was slightly higher with hue than with line samples, but this did not interact with delay. Alternative samples from each dimension and associatively different samples from the different dimensions both produced intertrial interference. In Experiment 2, pigeons learned new comparison associations to two samples from a prior many-to-one task. Later, their ability to match the remaining samples to the new comparisons was tested. Positive transfer occurred when samples previously paired with the same comparison replaced one another. Negative transfer occurred when opposing samples were interchanged. Apparently, the associatively related samples in many-to-one matching evoke similar representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

火花放电原子发射光谱法分析钢铁屑状样品的探讨

屑状样品其外观呈无规则状态,并具有一定的流动性。在一般情况下,它不能完全覆盖仪器的激发孔,无法形成一个密闭的氩气气氛,因此不能采用火花放电原子发射光谱法直接检测。为了能采用该法测定屑状样品,试验将钢铁屑状样品进行分类,根据各类金属屑状样品的强度和硬度选择合适的制样方法,将样品制备成规则的块状样品。其中塑性和韧性较好的样品采用冷压法制样,而超高强度、脆性大以及不适合冷压法制样的样品采用熔融法制样。制备好的样品选择合适的校准曲线,采用控样法,对样品进行定量分析。对样品10个不同部位测定的数据进行统计,测定结果的相对标准偏差(RSD,n=10)均小于2%,符合标准JJG 768—2005中的A级要求。用一级或二级标准物质/样品进行验证,测定值与认定值的差值都在标准物质规定的不确定度范围内。     

Contact allergy to 2,4,6-tris(dimethylaminomethyl)phenol

The use of saliva samples is an alternative to blood samples when a large number of control samples are to be compared by DNA investigations. The most convenient and safe method is by using cotton wool swabs. In this investigation the average DNA content of saliva samples taken by three different sampling techniques (i. e. cotton wool swab, filter paper, liquid saliva) was compared. In addition the possibility of a DNA mixture of saliva samples after intensive kissing was investigated by taking samples from voluntary pairs. Mixed STR patterns were found in five samples but restricted to the first sampling after kissing within max. 60 s.     

Validation of a new immunoblot assay (LiaTek HIV III) for confirmation of human immunodeficiency virus infection

BACKGROUND: Used as a supplemental assay, new anti-human immunodeficiency virus (HIV) immunoblots, employing recombinant and synthetic antigens, appeared to resolve the majority of samples with false-reactive Western blot results. Would it be possible to completely replace the Western blot by an immunoblot for confirmation and exclusion of HIV infection? STUDY DESIGN AND METHODS: The sensitivity of the new LiaTek HIV III immunoblot assay (Organon Teknika, Turnhout, Belgium) was tested on 416 Western-blot positive samples (386 HIV-1, 22 HIV-2, 1 HIV-1/2, and 7 HIV-O) and on 45 HIV-1 seroconversion samples. The specificity was tested on 146 samples from noninfected donors with false-positive results on a HIV screening test. RESULTS: All Western-blot-positive samples tested positive in the immunoblot (sensitivity: 100%). The immunoblot could not discriminate between HIV-1 and HIV-2 infection in 22 of 416 (5%) samples. The LiaTek assay showed reactivity in 28 of 45 seroconversion samples, whereas the Western blot reacted in 30 of 45 seroconversion samples. With false-positive donor samples, the immunoblot was indeterminate in 10 of 146 samples (specificity: 93%), and the Western blot was indeterminate in 44 of 146 samples (specificity: 70%). CONCLUSION: Like the Western blot, the immunoblot runs the risk of missing samples that are reactive by enzyme immunoassay during the early stage of HIV infection. Nevertheless, considering its superior specificity on false-positive donor samples, it appears that the immunoblot offers a cost-effective alternative to the Western blot assay for confirmation and exclusion of HIV infection.     

利用生产的炉渣样品制作X射线荧光分析曲线

为了消除X射线荧光光谱压片制样法制样存在的基体效应,利用实际生产炉渣样品与纯物质混匀技术配制内控标准样品制作校准曲线。实验室实验表明,利用滚筒混匀方式配制的样品均匀性与国家标准物质均匀性相当,且其含量与化学法测定结果一致,实现了根据实际生产样品情况灵活配制Al2O3和Ca O、Mg O系列校准样品,消除了基体效应,提高了X射线荧光光谱压片制样方法分析炉渣的准确性。     

烧结和锻造态Fe–2Cu–0.5C–0.11S材料的组织与力学性能研究

采用国产原料制备粉末冶金烧结态和锻造态Fe–2Cu–0.5C–0.11S材料,考察该材料的密度、显微组织、静态力学性能及动态超声疲劳性能。结果表明,粉末锻造工艺可以有效提高材料密度,锻件的平均密度可达到7.75 g/cm~3,其相对密度可达到98.7%;烧结件和锻件的显微组织主要由珠光体和铁素体组成,但锻件中的孔隙明显较少;锻件的力学性能相对于烧结件得到明显提升,其抗拉强度、屈服强度、延伸率及硬度分别为1018 MPa、778 MPa、4.0%及HB 206,比烧结件分别提高了155%、145%、167%及87%;锻件在106、107和108周次下相应的超声疲劳强度为437.7 MPa、351.1 MPa和281.7 MPa,比烧结件分别提高了82%、70%和59%;在相同疲劳寿命下,锻件的疲劳强度一直高于烧结件,但随着疲劳寿命的提高,两者之间的差值变小;烧结件和锻件在拉伸时均表现出脆性断裂的特征,同时存在微观塑性变形区域。     

光学加工对GaAs窗口晶体断裂模数的影响

用四点弯曲法测量了GaAs晶体断裂模数 ,其结果表明加工方法是影响GaAs晶体断裂模数测量值的重要因素。切割加工的GaAs晶体的断裂模数最低 ,研磨加工GaAs晶体的断裂模数其次 ,机械抛光的断裂模数再其次 ,而机械抛光后再化学抛光的GaAs晶体的断裂模数平均值最高 ,其平均值约为 135MPa。光学加工表面损伤层及损伤层中的缺陷、裂纹和应力将导致GaAs晶体的断裂模数值下降。     

基于BP神经网络钒钛烧结矿低温还原粉化性能预测

为了改善钒钛烧结矿的低温还原粉化性能,将BP神经网络算法应用于钒钛烧结矿低温还原粉化性能预测中,指标数据的样本分为输入样本和输出样本,其中:输入样本为配碳量、碱度、w(Mg O)以及FMG粉配比,输出样本为钒钛烧结矿RDI+3.15,运用BP神经网络算法探索输入样本与输出样本间的关系。结果表明:BP神经网络模型适用于烧结矿还原粉化性能的研究,可以根据输入样本有效的预测输出样本,且平均相对误差为5.7%,满足工程实践中预测精度的要求,为钒钛烧结矿生产提供了指导。