火焰原子吸收法对水中的锰元素含量的测定

文章利用火焰原子吸收光谱法直接测定了水中锰元素的含量。标准溶液的配制选用了标准加入法。研究了仪器的最佳工作条件;实验结果表明利用该方法测定本水样中Mn元素的相对偏差值小于2.3%,检出限为:3.0μg/L,测定范围为:2.5～300μg/L,该方法简单易行,方便准确。     

氢化物发生原子荧光光谱法测定菥蓂中的有机硒和无机硒

建立了氢化物发生原子荧光法测定菥蓂中硒的分析方法,研究了仪器的工作条件、试剂以及干扰元素对硒原子荧光强度的影响,对菥蓂中无机硒和有机硒的进行分离提取测定。结果表明:该方法硒的检出限为0.022μg/L,相对标准偏差为1.29%,线性范围为0～100μg/L,回收率为100.6%～103.6%。菥蓂根、茎、叶的总硒含量分别为:0.0 393±0.001μg/g,0.1 042±0.002μg/g,0.0 789±0.001μg/g;菥蓂茎中有机硒含量为0.0 697±0.0 02μg/g,占总硒的67%以上。     

火焰原子吸收法快速测定食盐中的微量硒

本文建立了用火焰原子吸收光度技术快速测定食盐中微量硒的方法。研究结果表明,在最佳实验条件下,硒的线性范围为0.00-0.40μg.mL-1,样品测定的RSD为1.05%(n=6),结果与样品标示值一致。     

氧弹燃烧-原子荧光测定西洋菜中硒的含量

本文为测定西洋菜中硒含量提供了一种更加便捷、准确、环保的方法。实验表明,利用氧弹燃烧-原子荧光7次测定西洋菜中硒的含量相对标准偏差值RSD=2.04%,精密度较好,在实验同时测定水质硒标准样品(GSBZ50031-94)7.64μg/L±0.82,其测定结果分别为7.31μg/L和7.45μg/L,均在范围内,表明其准确度高。     

几种猕猴桃中痕量元素铁和锌的测定

通过一系列实验对仪器的参数进行了优化,对样品的消解剂进行筛选,建立了测定猕猴桃中铁锌元素含量的微波消解-火焰原子吸收光度分析方法。为了验证该方法的可靠性,又进行了加标回收试验,方法的回收率在95%~107%之间。测定结果为猕猴桃样品的干重铁含量在55.3~117.5μg/g之间,湿重铁含量在8.17~20.5μg/g之间,干重锌含量在25.6~52.2μg/g之间,湿重锌含量在3.78~7.16μg/g之间。     

石墨消解-原子吸收测定土壤中的锌和镉

采用石墨消解的方法进行样品消解,并用原子吸收光谱法测定土壤中锌和镉的含量。实验结果表明:锌在石墨消解结合火焰原子吸收光谱法中锌浓度在1 mg/L以下成线性相关,相关系数R2=0.9995,该方法的最低检出限为0.02 mg/kg。而镉元素在小于10μg/L之间成指数函数相关,相关系数R2=0.99889,该方法的最低检出限为0.02 mg/kg。测定结果精密度、准确度令人满意。     

流动顺序注射分离富集-火焰原子吸收光谱法检测污水和废水中Pb Cd Cu Zn

采用D412螯合树脂作为流动顺序注射分离富集微柱填充材料,同火焰原子吸收光谱仪联用,结合所优化的样品酸度,进样速度,淋洗条件和洗脱条件,快速测定污水和废水样品中Pb,Cd,Cu和Zn的含量,样品上柱10 mL富集时,相对标准偏差(RSD)<5.00%,以空白溶液11次测定的标准偏差的3倍求得检出限Pb:1.3μg/L,Cd:0.56μg/L,Cu:0.91μg/L,Zn:0.48μg/L,加标回收率89%-98%。     

石墨炉原子吸收分光光度法测定硒

火焰原子吸收法测定硒,其测量波长(19.00nm)处火焰背景吸收严重,测定效果较差,石墨炉原子吸收法可测定0.015-0.2mg/L水和废水中的硒.     

微波消解-火焰原子吸收光谱法测定洗发水中硒的含量

本文建立了微波消解-火焰原子吸收光谱法测定洗发水中硒的含量的方法,方法线性范围为0.3～50.0μg/mL;当取样量为0.5g,定容体积为25mL时,本方法测定硒的检出限为4.5mg/kg,定量限为15mg/kg;采用不同浓度水平的硒标准溶液进行精密度试验,相对标准偏差（n=7）在0.6%～2.7%之间;采用人为添加二硫化硒的洗发水样品进行加标回收实验,回收率在90.0%～107.8%之间,满足《化妆品中禁用物质和限用物质检测方法验证技术规范》的技术要求。此方法具有优异的精密度、准确度和可操作性,适用于样品的批量测定,能在保证结果准确性的前提下大大提高检测效率。     

石墨炉原子吸收法测定凉山彝族植物药中的硒

采用Ni(NO3)2-Mg(NO3)2溶液作为混合基体改进剂,微波消解-石墨炉原子吸收光谱法测定了五种彝族植物药中硒的含量。结果表明:五种样品中硒含量在0.095 9μg·g-1和1.411μg·g-1之间。且该方法的标准曲线线性关系良好(R=0.9989),回收率为95.1%~101.3%,RSD值(n=8)为3.73%~7.56%。所建方法简便、快速、准确、可靠,可用于彝药中硒的含量测定。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、环氧树脂、不饱和聚酯树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.