微波法合成碳量子点及槲皮素对荧光的猝灭

以β-环糊精为碳源,采用微波法合成碳量子点。探讨了最佳的微波时间、微波功率、β-环糊精与PEG-200的配比及p H值对碳点荧光强度的影响。通过F-4600荧光分光光度计分析,碳点的激发波长在350 nm,发射波长在440 nm左右。该碳量子点的荧光能被槲皮素猝灭。据此,建立了快速有效的槲皮素猝灭碳点的分析法。槲皮素的线性范围1×10-6~8×10-4mol/L,对银杏叶片中黄酮含量测定结果满意。     

荧光光度法测定煤矸石中微量锗

在H3PO4介质中锗(Ⅳ)与桑色素反应生成配合物,使溶液的荧光明显增强,据此建立了测定微量锗的荧光分析新方法。体系的激发波长λex=420 nm,发射波长λem=505 nm,锗的质量浓度在20-600μg/L范围内与ΔF存在良好的线性关系,方法的检出限为1.1×10-7g/L,已用于煤矸石中微量锗的测定,结果满意。     

分散液相微萃取荧光法测定果蔬中残留吡蚜酮

[目的]利用分散液相微萃取和表面活性剂增敏,建立果蔬中吡蚜酮残留量的荧光分光光度快速测定法。[方法]用二氯甲烷作为萃取剂,丙酮作为分散剂对样品进行前处理。以水作溶剂,320μL十二烷基硫酸钠(SDS)(0.1 mol/L)作增敏剂,室温静置10 min。1 cm石英比色皿作吸收池,于激发波长(λ_(ex))312 nm、发射波长(λ_(em))349 nm处测定荧光强度。[结果]在0.02~1.00 mg/L范围内,吡蚜酮浓度与荧光强度线性关系良好,检出限为0.0196 mg/kg。加标回收率为87.73%~99.06%,RSD为2.93%~9.67%。[结论]新建方法可用于水果蔬菜中吡蚜酮残留测定。     

荧光法测定食盐中碘酸根的研究

在0.05 mol/L的H2SO4介质中,过量I-存在时,IO3-会使罗丹明B发生荧光猝灭,建立了测定IO3-的方法.该体系的荧光发射波长λ=580 nm,激发波长λ=557 nm,体系的荧光强度降低值与IO3-含量在0.6～1.6 μg/mL之间呈良好的线性关系.回归方程为△F=18.30 C＋119.5（C的单位μg/mL）,相关系数r=0.9810,检出限为0.0052 μg/mL.该法灵敏度较高,选择性好,操作简单,用于含碘食盐中碘酸根含量的测定,结果满意.     

水杨基荧光酮-HP-β-CD-荧光猝灭法测定Fe(Ⅲ)

在pH 5.20的NaAc-HAc缓冲溶液中,在羟丙基-β-环糊精和Triton X-100的存在下,水扬基荧光酮(SAF)本身呈较强的荧光(λex=365nm,λem=537nm)微克铁(Ⅲ)在此条件下,能与SAF生成配合物而使SAF-HP-β-CD-Triton X-100体系产生荧光熄灭现象。荧光减弱(△F)与铁(Ⅲ)浓度在0~3.0μg/25mL范围内呈良好的线性关系,该反应对铁(Ⅲ)的检出限为1.23μg/L,已经应用于自来水中微量铁的测定。且相对标准偏差均小于0.6%,加标回收率均在98.0%~101.4%。结果表明:羟丙基-β-环糊精对所研究的荧光体系均有增敏增稳作用。     

白杨素增敏荧光法测定粮食样品中的痕量锰

提出了一种用新型多核三元配合物荧光增敏技术测定粮食样品中痕量锰(Ⅱ)的新方法.在含一定量甲醇和表面活性剂Tween-80,pH 4.5的醋酸-醋酸钠缓冲溶液中,白杨素、铬(Ⅲ)和锰(Ⅱ)之间能形成物质的量比为4∶1∶2且具有强荧光发射特性的新型多核三元混配配合物,其最大激发波长和发射波长分别为225和342 nm.在优化的测定条件下,锰(Ⅱ)含量在0.396～16.2 μg/L范围内与配合物的荧光发射强度F之间呈良好的线性关系,线性回归方程为:F=298+40.4c(μg/L),相关系数r=0.999 0,方法的检出限为0.352 μg/L(3σ).该方法具有灵敏度高、选择性好、操作简单、快速的优点,可用于粮食中痕量锰(Ⅱ)的测定,实样回收率为100%～104%.     

铁猝灭荧光分析法测定环丙沙星的研究与应用

在pH=4.5的HAc-NaAc缓冲介质中,Fe3+能与十二烷基硫酸钠(SDS)和环丙沙星作用,使其荧光值显著减小,据此建立了Fe3+-SDS-环丙沙星体系荧光猝灭法测定微量环丙沙星的新方法。该体系的最大激发、发射波长分别为λex=275 nm,λem=441 nm。环丙沙星在4.0×10-7~3.6×10-6mol/L的浓度范围内与荧光值呈良好的线性关系,R=0.995 8,相对标准偏差为0.76%(c=3.0×10-6mol/L)。     

槲皮素-锆(Ⅳ)-柠檬酸-十二烷基磺酸钠体系荧光光度法测定槲皮素的研究

在 0 .5 4 mol/L盐酸介质中 ,有十二烷基磺酸钠的存在下 ,槲皮素与锆 ( )和柠檬酸形成多元荧光配合物 ,其组成比为槲皮素∶锆 ( )∶柠檬酸 =1∶ 2∶ 2。配合物的激发与发射波长分别为432和 495 nm时 ,槲皮素浓度在 1 .0× 1 0 -6～ 1 .0× 1 0 -5mol/L范围内与荧光强度成线性关系 ,检出限为 2 .34× 1 0 -7mol/L。该法用于鸡骨草中黄酮类化合物的测定 ,结果满意     

三维荧光法测定人尿中1-羟基芘、β-萘酚和9-羟基菲

应用三维荧光法建立了直接测定人尿中的1-羟基芘、β-萘酚、9-羟基菲的新方法。通过β-环糊精增敏,三维荧光扫描选择测量波长。结果表明,在波长对λex/λem=275/385 nm时测定1-羟基芘,其线性范围和检出限分别为0.007～8.00μmol/L和2.30 nmol/L;在波长对为λex/λem=325/350 nm时测定β-萘酚,其线性范围和检出限分别为0.049～50.0μmol/L和12.5 nmol/L;在波长对为λex/λem=260/475 nm时测定9-羟基菲,其线性范围和检出限分别为0.023～40.0μmol/L和7.90 nmol/L。该方法已成功用于人尿中痕量1-羟基芘、β-萘酚、9-羟基菲的测定,与高效液相色谱法比较,结果满意,同时对β-环糊精增敏机制进行了初步探讨。     

荧光分析法测定芒果叶总黄酮含量的研究

采用荧光分析法测定芒果叶中总黄酮含量。根据Al3+与黄酮类化合物形成稳定的荧光络合物,以芦丁为标样,采用低共熔溶剂作为提取溶剂,对芒果叶总黄酮进行微波辅助提取,选择激发波长λex=436 nm、发射波长λem=483 nm条件下,测定四种品种的芒果叶中总黄酮含量。该方法检测限为0.12μg/m L,线性范围在0.16~0.80μg/m L之间,线性方程为:y=11.41+1789.2x,线性相关系数为r=0.9989,回收率为97.2%~102.5%,相对标准差(RSD)为1.39%。荧光分光光度法测定芒果叶中总黄酮含量准确度较高,操作简便,成本低。     

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.     

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.     

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。     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。     

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.     

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.     

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.