电感耦合等离子体测定茶叶中的铅——微波消解与电热板消解比较试验

用微波消解法与电热板消解法消解茶叶,用电感耦合等离子体测定消解液铅含量,对比两种消解方法。     

化学需氧量（COD）消解液的配制

由于消解液购买成本较高,根据公司的实际情况,需要在实验室中找寻低成本消解液的配制方法,从而达到节约成本的目的。本实验根据消解液在紫外-可见光谱中的特征,为自配消解液提供了光谱依据。结果表明,用实验所得的方法配制消解液在测定结果的精密度和准确度方面均能符合要求,而且需要的成本与购买的药剂相比大幅度减少,能够起到降低分析成...     

各种电镀槽液的管理和处理方法

电镀槽液的管理和处理方法是决定电镀厂产品质量和经济效益的重要手段。为此,本文详细论述了各种电镀槽液的处理方法,其中包括1,除油槽液的处理,2,氰化物镀铜或铜锡合金槽液的处理;3,镀镍槽液的处理;4,镀铬槽液的处理;5,镀锌槽液(氨三乙酸-氯化铵镀液和氰化镀锌槽液)的处理。特别是对镀镍槽液的处理,不但论述了常规处理方法还论述了镀镍槽液的大处理方法,考虑到可能存在杂质的情况,分别论述了当含有铁、铬、铜、胶体杂质时的处理方法,对电镀厂的质量管理和故障处理将有参考价值。     

化学镀镍层的性能及工艺选择

概述化学镀镍层的性能,影响镀层耐蚀性、硬度和耐磨性能的各种因素.列出了7种化学镀镍液的成分组成,讨论了各种不同基体材料化学镀镍前处理的方法及槽液维护的措施.     

分光光度法测定水中COD的方法探讨

文章通过对哈希回流法的改进,利用分光光度法并采用自主配置COD消解液代替进口消解液测定水中COD。试验证明,分光光度法与自配消解液能够满足测量的准确度和精确度的要求,与国标法相比的是一种操作简单、省时、经济、可靠实用的分析方法。     

石墨炉原子吸收分光光度法测定土壤中的镉-全消解法和微波消解法比对实验

用微波消解法与全消解法消解土壤标准样品,用石墨炉原子吸收光谱法测定消解液铅含量,比较两种消解方法的精密度和准确度。微波消解法的相对标准偏差为3.8%,全消解法为8.6%。与标准值的相对相差比较,微波消解法低于10%,电热板消解法高于19%。微波消解法的测出值均高于电热板消解法。     

粉煤灰-氢氧化钠浆液槽放大准则数值模拟研究

粉煤灰-氢氧化钠浆液槽固液两相混合效果对整条高铝粉煤灰制备氧化铝工艺生产线的顺利运行至关重要,以某单位生产现场浆液槽为基准建立了3个几何相似的搅拌槽模型,应用多相流模型对搅拌槽固液悬浮的放大准则进行了研究。模拟计算了达到均匀悬浮时搅拌槽内各项性能参数的变化情况,分析了不同放大方法的效果,计算得到一种适合于粉煤灰-氢氧化钠浆液槽固液悬浮的放大判据N∝D-0.842,在节省功耗的基础上可以使搅拌过程较好地重现。     

从微氰镀液中沉积黄铜镀层的初步研究

前言早在十九世纪末,电镀黄铜的工艺就已成熟。早期使用的槽液配方由两种金属的氰化物组成或由两种金属的碱性碳酸盐组成。当时认为后者比前者更好控制。随后,人们研究了在其他一些槽液如:硫氰酸盐,硫酸盐,酒石酸盐和锌酸盐,焦磷酸盐等溶液中沉积黄铜的可能性。1960年Lainer研究了在他以前所出现的所有不同类型的槽液后认为,没有一种可以满意地代替氰化物槽液。这个结论迄今被认为是正确的。     

微波消解-火焰原子吸收法测定土壤中铜锌铅镍锰

讨论了用原子吸收光度法测定土壤中铜、锌、铅、镍和锰。通过硝酸-氢氟酸-高氯酸以及硝酸-盐酸-过氧化氢体系消解液对土壤样品消解,选择出微波最佳消解条件。对硝酸-氢氟酸-高氯酸体系消解液和硝酸-盐酸-过氧化氢体系消解液进行消解对比试验,发现前者将土壤样品中的铜、镍和锰完全消解,后者能将样品中的锌和铅消解完全。微波消解土壤和传统电热板消解在测定前都需将消解液中剩余的酸赶尽,但与传统电热板消解相比,微波消解操作简便快速,可提高工作效率。     

不同环境样品中重金属前处理方法探索

探索环境废水、土壤、空气不同样品类型重金属测定的前处理方法,分别采用电热板加热消解、全自动石墨消解和微波消解三种方法进行样品消解比较,得出各种类型样品的最佳前处理方法。     

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。