比值-导数分光光度法测定含苯胺废水中氨氮的含量

在测定含苯胺废水中的氨氮含量时,由于苯胺和氨氮与纳氏试剂形成的络合物的吸收光谱彼此重叠.因此在采用国标法测定该类废水的氨氮含量时,苯胺对其干扰严重,需采用预处理法消除干扰.根据吸光度比值一导数光谱法的原理,定量分析测定了含苯胺废水中氨氮的浓度,且省去了混凝沉淀、蒸馏等复杂的预处理步骤.实验表明,当氨氮质量浓度<2.4 mg/L,时,吸光度比值的的导数值与相应的氨氮浓度呈良好的线性关系.     

H193733型氨氮测定仪测量废水中氨氮含量

简要论述了H193733型氮氮测定仪测量废水中氨氮含量的方法，该方法运用国标GB7479-87纳氏比色法的测定原理，是一种全新快速测定水中氨氮含量的方法，操作简便快速，灵敏，结果准确，适合于工矿企业废水氨氮含量及应急测定。     

蒸馏-中和滴定法测定废水中氨氮含量的改进

对蒸馏-中和滴定法测定废水中氨氮含量的分析方法进行了研究。用磷酸盐缓冲溶液代替轻质氧化镁调节水样呈微碱性,以硫酸代替硼酸作为吸收液,以氢氧化钠标准溶液代替硫酸标准溶液滴定,经过实际样品和标准样品的测定,并与国标法进行了试验比对,证明改进后的方法对于高氨氮含量废水测定具有精密度好、准确度高的特点。     

蒸馏-中和滴定法测定废水中氨氮含量的改进

对蒸馏-中和滴定法测定废水中氨氮含量的分析方法进行了研究。用磷酸盐缓冲溶液代替轻质氧化镁调节水样呈微碱性,以硫酸代替硼酸作为吸收液,以氢氧化钠标准溶液代替硫酸标准溶液滴定,经过实际样品和标准样品的测定,并与国标法进行了试验比对,证明改进后的方法对于高氨氮含量废水测定具有精密度好、准确度高的特点。     

ADC发泡剂废水中氨氮的快速测定

介绍ADC发泡剂废水中氨氮含量的快速测定过程及采用的甲醛测定法，并分析和探讨了测定过程中出现的问题。     

甲醛对氨氮测定的影响及消除

我公司为确保尿素严品的质量,工艺上采取加入甲醛以增加尿素颗粒强度,因此尿素水解净水中含有少量甲醛.当用纳氏试剂分光光度法测定水解净水中氨氮含量时,甲醛会干扰测定,甲醛含量较高则显色时溶液浑浊,使测定无法进行.氨氮是废水排放的重要指标,水解净水中氨氮含量的准确测定尤为重要.要准确测定水解净水中的氨氮含量必须消除甲醛的干扰.     

甲醛对氨氮测定的影响及消除

目前,水和废水中氨氮测定通常采用纳氏分光光度法,此法具有操作简便,快速、准确的特点。公司工业下水和废水中由于含有少量甲醛,甲醛的存在将影响氨氮的测定,为此在分析时对样品作适当的预处理,仍可采用纳氏分光光度法测定氨氮。     

应用快速测定仪测定废水样中的氨氮含量

应用美国哈希COD快速测定仪(进口)与欧陆科仪COD快速测定仪(国产)测定实际水样的氨氮含量。通过与国标(纳氏试剂分光光度法)的实验结果进行对比,通过精密度、准确度及加标回收等实验结果,得出:两种COD快速测定仪测定实际水样的氨氮含量均具有良好的线性关系,虽然灵敏度比国家标准方法低,但精密度和准确度均较高,符合国家检测要求,与国家标准方法的测定结果无显著性差异,而且分析速度快,试剂耗量低,二次污染少,值得在废水监测中推广使用。     

用X-matepro仪测定废水中的氨氮浓度

介绍用X-matepro仪测定废水中的氨氮浓度的方法.实验结果表明,该法可满足废水中氨氮浓度快速检测要求,可根据氨氮浓度的高低、样品来源合理选择添加硫酸铝溶液,样品浓度超高时必须进行稀释,避免电极受污染.     

酚试剂分光光度法测定饮用水中甲醛的改进

目的:通过对试验条件的研究与改进,提高方法灵敏度,确保测定饮用水中甲醛的酚试剂分光光度法更加完善和稳定。方法:利用甲醛与酚试剂反应生成嗪,嗪在酸性溶液中被高铁离子氧化生成蓝绿色化合物,颜色深浅与甲醛含量成正比[1],据此可测定饮用水中甲醛含量。文章对入射波长、显色剂酸度、显色剂浓度、显色剂用量、酚试剂用量、加酚试剂后静置时间、显色温度和显色时间等影响因素进行了全面研究;并对改进后方法的灵敏度、精密度、准确度和检出限进行了探讨。结果:方法经改进后,甲醛浓度在0~0.20 mg/L范围内与吸光度呈良好线性关系,相关系数为0.9997,灵敏度为0.96 A/(mg/L),检出限为3×10-3 mg/L,RSD为1.0%~2.3%,加标回收率为97%~102%。结论:该法经过改进,用于测定饮用水中甲醛含量更加稳定,提高了方法灵敏度,检出限更低,精密度和准确度更好;优于原法和国标方法,是一个简便、快速、准确、可行的测定饮用水中甲醛含量的方法。     

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.     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008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、不饱和聚酯树脂、环氧树脂)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.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006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生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。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（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。