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以硝酸钴、硝酸铝和氢氧化钠为主要原料,采用水热法通过一系列正交对比实验制备了较纯净、结晶完整,直径为100nm左右且分散性良好的CoAl2O4纳米晶。用X射线衍射仪(XRD)、透射电子显微镜(TEM)及X射线能量色散谱仪(EDS)测定了粉体的晶相组成、微观形貌和元素组成。实验结果表明:水热法制备CoAl2O4纳米晶的最佳工艺条件为水热温度T=200℃、水热时间t=16h、前驱液摩尔浓度C=0.25mol·L-1、pH值=11、Al3+:Co2+=4:1(摩尔比)。球形的CoAl2O4粉体是单晶且沿[311]方向取向生长。 相似文献
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以氧化锆(ZrO2)、硼酸(H3 BO3)和碳(C)粉为原料,研究了不同碳粉(活性炭、石墨)与前驱体粒度、温度及保温时间对碳热还原法制备硼化锆(ZrB2)粉体的影响.通过X射线衍射(XRD)分析合成粉体物相,扫描电镜(SEM)观察合成粉体形貌,并通过化学方法分析了合成粉体中的C、O含量.结果表明:以活性炭为碳源合成的粉体形貌呈条棒状,以石墨为碳源合成的粉体形貌呈规则的块状;合成粉体的粒度随前驱体粒度减小而减小,形貌由规则的块状逐渐转变为圆滑的不规则形貌,合成ZrB2粉体最小平均粒度约为1.69μm,产物中C含量随前驱体粒度减小而减少,O含量随前驱体粒度减小而增加,氧含量最低为0.54wt%;碳热还原法合成ZrB2粉体在1500℃下是可行的,但直到1900℃碳热还原反应合成ZrB2才进行完全;碳热还原反应合成ZrB2粉体最佳的反应条件为1900℃保温30 min. 相似文献
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醇水加热-水热法制备稳定Y-Ce-ZrO2纳米粉体 总被引:10,自引:0,他引:10
用醇水加热法制备前驱体,再由水热法制备摩尔分数为2 %Y2O3-5.5 %CeO2稳定的纳米四方相ZrO2.采用XRD,FTIR,TEM,SEAD分别对前驱体和纳米ZrO2粉体进行表征.研究了溶液的浓度、水浴时间、水热时间对ZrO2粉体晶型和形貌的影响.结果表明当溶液中ZrOCl2·8H2O的浓度为0.2 mol/L,醇水体积比例为5∶1,溶液加热至75 ℃,保温60 min;再经200 ℃水热处理6 h,制得的Y2O3-CeO2-ZrO2粉体的平均粒径为10 nm左右,粒度分布窄,分散性好. 相似文献
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超声场中沉淀法纳米氧化锌的制备与表征 总被引:3,自引:0,他引:3
将超声辐射应用于以硫酸锌(ZnSO4·7H2O)和草酸(H2C2O4·2H2O)为原料的沉淀法制备纳米氧化锌粉体的工艺过程,制备了平均晶粒尺寸为26nm的氧化锌粉体。通过XRD,DTA—TG和SEM等技术研究了纳米氧化锌的合成过程及粉体性能。结果表明:超声辐射引入普通沉淀法,超声波的空化作用可使前驱体颗粒细化,抑制其团聚并延缓其向凝胶转变,从而可制备出氧化锌纳米粉体。这种方法所得纳米氧化锌粒子外貌为球形,粒度分布均匀,分散性好。 相似文献
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凝胶网格法制备纳米CdFe_2O_4粉体及其对CH_3SH的气敏性 总被引:1,自引:0,他引:1
以无机盐为原料,采用凝胶网格法合成了尖晶石型复合氧化物CdFe2O4的前驱体,并在700°C热处理后得到了纳米尺寸CdFe2O4粉体,利用XRD和TEM对粉体的形貌、结构进行了表征。研究表明,用凝胶网格法制备的CdFe2O4结晶良好,粒度分布均匀,平均粒径为21.3 nm。以CdFe2O4纳米粉体为原料制备了厚膜型气敏元件。CdFe2O4是电子导电型半导体,当加热电压为6.5 V时,该元件对甲硫醇具有较高的灵敏度,较好的稳定性和选择性。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
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. 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
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. 相似文献
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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. 相似文献
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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. 相似文献
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
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。 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
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. 相似文献