磷酸四钙的制备

以硝酸钙溶液、磷酸氢二铵溶液、碳酸铵溶液为原料,通过超声法制备磷酸四钙(TTCP)的前驱体Ca5(PO4)3 OH-CaCO3混合物,将其高温煅烧后得到产物TTCP,并通过SEM、XRD、FTIR对其结构进行表征.结果表明,超声功率为300 W、温度为20℃、超声时间为2 h时能够得到粒径为1.1 nm的前驱体,且煅烧...     

微波烧结法制备TCP/TTCP复合生物陶瓷材料的研究

采用微波烧结方法制备TCP/TTCP复合磷酸钙生物陶瓷材料,以四水硝酸钙(Ca(NO3)2·4H2O)和磷酸氢二铵((NH4)2HPO4)为初始原料制备磷酸三钙(TCP)和磷酸四钙(TTCP).研究了当代PCP/TTCP(物质的量)配比为1:1时,不同的烧结温度对复合钙磷陶瓷的结构和晶相的影响.对烧结后的样品在模拟体液中进行了浸泡实验,监测了浸泡过程中的pH值变化,通过扫描电镜、X射线衍射分析对浸泡后试样的结构和晶相的变化进行了分析.结果表明微波烧结制备的磷酸钙生物陶瓷的主晶相是HA,其结构均匀,致密度较好.且在1200℃下微波烧结HA能稳定存在,陶瓷具有良好的表面生物活性.浸泡溶液的pH值变化幅度小(在7.40～7.72之间),接近中性.     

磷酸钙骨水泥制备方法的改进及其性能研究

采用2种方法探索了磷酸钙骨水泥(CPC)固体粉末的制备,即沉淀法和固相反应法,并合成了CPC;对CPC的固化时间、抗压强度、产物物相组成等进行了分析。沉淀法生成的固相粉末为磷酸三钙、焦磷酸钙,通过实验确定适当的调和液为柠檬酸,使固相粉末拥有骨水泥特性,并探讨了温度、缓冲液、模拟体液浸泡等对其性能的影响。固相反应法制备的固相粉末应为磷酸四钙(TTCP),但在空气中,1 500℃下煅烧6h制得的TTCP结晶度不好且含有杂质CaO。综合2种方法,结果表明以焦磷酸钙、磷酸三钙为主要成分的骨水泥的性能优于以磷酸四钙为主要成分的骨水泥。     

低温固相反应制备氧化锌微粉研究

以Zn(NO3)2、Zn(Ac)2、ZnCl2和Na2CO3为原料,通过低温固相反应方法制备出了ZnO超细粉体。讨论了制备过程中不同的反应体系、反应物配比、煅烧温度和保温时间对ZnO粉体平均粒径的影响,并对其作用机理进行了分析。实验结果表明:在低温下,固相反应能快速进行;以Zn(NO3)2和Na2CO3为反应体系,能得到结晶度好、分散性较好、平均粒径为20nm左右的ZnO粉体。     

空冷型高温轴换热及应力分析

对CRC辊式破碎机空冷型高温轴进行了换热模拟及热态下的应力分析。模拟分析结果表明,带扰流叶片的冷却风道具有更强的冷却换热效果,不同边界温度和不同冷却风量会使高温轴产生较大且不同方向的温度差和热梯度,进而产生较大的额外热应力。通过将热态下的模型导入应力分析软件,进一步分析了热梯度对轴应力的影响,发现轴在热态下的等效应力远大于冷态下的等效应力,设计选材时应评估热梯度应力的影响,采取适当措施减轻或平衡应力。     

高温改质煤沥青挤压成型工艺参数的研究

以高温改质沥青为粘结剂,在不同条件下挤压成型,经焙烧和石墨化得到样品,研究了成型工艺参数对制品性能的影响。结果表明:高温改质沥青有利于提高制品的体积密度。高温改质沥青的糊料的塑性范围较窄。对温度影响敏感。混捏温度制度的设定应依据粘温曲线中沥青的拐点范围,凉料温度和缸嘴温度应依据在保证压型速度的条件下,挤压压力尽可能低的原则制定。     

氯化亚铁生产高品质氧化铁红的工艺研究

以氯化亚铁晶体为原料,在氧化氛围的固定床反应器中高温反应制备高品质的氧化铁红。主要研究了氧化温度和反应时间对产物的物相、纯度、色相、吸油量和粒径的影响,并讨论了氧化温度与氧化时间的关系。通过实验得到了制备高品质氧化铁红的最佳工艺条件：氧化温度为400 ℃,氧化时间为60 min。在此条件下得到的产物纯度为99.5%,色相纯正鲜艳,粒径为100~150 nm,吸油量为0.241 g/g。通过研究氧化温度与反应时间的关系,证明温度升高所需要的反应时间相应变短,即反应过程具有时温等效性。     

高温作用下混凝土耐久性劣化性能研究

建筑结构中的混凝土材料在遇到火灾时,往往会暴露在高温的作用下,而高温作用后混凝土的相关性能对建筑物的使用安全性至关重要.本文介绍了高温对混凝土的物理性能和力学性能的影响.混凝土试块会经过相对较低温度(小于300℃)和相对高的温度作用,并通过不同的冷却方式后得到混凝土试块的抗压强度.高温作用后混凝土的抗压强度会严重劣化,混凝土的剩余强度也随着冷却制度的不同而不同.随着温度的升高,混凝土的断裂能逐渐降低.且高温作用后混凝土抗毛细吸水性能严重劣化,喷水冷却后混凝土的毛细吸水能力显著增大.     

微注射成型模腔聚合物界面传热评估研究

实验装置由模具和一个超高速相机以及一系列窗口组成,以评估高温超导的传热性能。窗户的内表面经过激光加工,形成了一系列的表面形貌,通过实验得到了材料在不同工艺条件下的冷却曲线,探讨了熔体和模具温度、注射速度、填充压力和表面形貌对冷却曲线的影响,利用有限元软件包Moldflow对实验进行了模拟,找出了最适合冷却曲线的传热系数(HTC)值,从而将HTC的变化转换成探索过程变量的函数。     

真空法制备氟化氢铵的工艺研究

研究以氟硅酸氨化制备白炭黑得到的氟化铵溶液为原料,经酸化、真空浓缩、冷却结晶、固液分离、真空干燥等工艺过程制备氟化氢铵。通过考察浓缩温度、体系中水蒸发量、结晶温度等因素对氟化氢铵纯度的影响,得到最佳工艺条件:浓缩温度为75℃,体系中水蒸发量为70%,结晶温度为25℃,此条件下得到的氟化氢铵纯度为98.7%,为斜方晶型。产品经检测符合HG/T3586-1999优等品要求。     

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.     

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。     

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.