响应面法优化茶叶茶多酚提取

采用水溶液浸提法提取宁德市某茶企茶叶中的茶多酚,并结合响应曲面法对水提取茶多酚的工艺参数进行设计优化,结果表明最佳条件为反应温度81.3℃,液料比为25.6m L/g,反应时间为2.55h,该条件下茶多酚提取率为21.17%.     

汽爆法生产糠醛新工艺

研究了用汽爆法取代糠醛生产工艺中的酸解步骤,得出了新工艺的最佳工艺参数。取玉米秸秆20 g在1.4 MPa压力、维压时间4 min下汽爆,所得物料用60 mL热水（80 ℃）水提2 h,水提液中木糖含量可达9.96 g/L,木糖浸出率为2.79%。取350 mL水提液,加入甲苯30 mL、5%稀硫酸10 mL,于165 ℃反应精馏3 h,糠醛得率可达84%,糠醛总的质量收率为2.2%。结果表明,本工艺产生的三废量大幅减少。     

Dawson型磷钨酸催化合成乳酸月桂醇酯

用 Dawson型磷钨酸催化合成乳酸月桂醇酯.实验结果表明 Dawson型磷钨酸有较高的催化活性、反应时间短、酯收率高、工艺简单.最佳工艺条件为醇 /酸摩尔比为 1.5 1,催化剂用量为 0.3%,带水剂甲苯体积(mL)与反应物质量(g)之比为 0.41 1～ 0.5 1,反应温度为 115～ 140℃,反应时间 30～ 50min,在此条件下,酯收率可超过 93%.     

甲酸/乙酸/氯化钠催化玉米芯水解条件优化

为解决目前糠醛行业使用无机酸做催化剂存在的严重污染及收率低等问题,提出两步法有机酸/无机盐复合体系催化玉米芯水解生产糠醛新工艺。文中以获得第1步水解玉米芯过程中较高的五碳糖收率和低的糠醛质量浓度为目的。研究了反应温度、反应时间、酸质量分数及氯化钠浓度对玉米芯中半纤维素水解的影响。通过响应曲面法,对水解条件进行了优化,建立了糖收率和糠醛质量浓度的2个二次多项式模型。由响应面分析和模型方程优化得出玉米芯水解的最佳水解条件:反应时间90 min、氯化钠浓度1.5 mol/L、温度134.7℃和酸质量分数为4.67%,此时糖收率为36%、糠醛质量浓度为1.98 g/L,为下一步五碳糖水解生产糠醛提供了较为满意的糖质量浓度和糠醛质量浓度,同时在最佳水解条件下的验证实验结果与模型预测值十分接近,说明模型是适用的。     

葡萄糖制备5-羟甲基糠醛工艺研究

为实现5-羟甲基糠醛绿色化、低成本制备,以可再生资源葡萄糖为原料,固体酸为催化剂,在水-γ-戊内酯双相介质中经酸化水解制备出5-羟甲基糠醛。考察了反应温度、反应时间、催化剂用量、葡萄糖用量对5-羟甲基糠醛收率的影响。结果表明,最佳工艺条件:反应温度190℃,反应时间43 min,催化剂用量0. 3 g,葡萄糖用量0. 15 g,在此条件下,5-羟甲基糠醛的收率44. 7%。     

葡萄糖制备5-羟甲基糠醛工艺研究

为实现5-羟甲基糠醛绿色化、低成本制备,以可再生资源葡萄糖为原料,固体酸为催化剂,在水-γ-戊内酯双相介质中经酸化水解制备出5-羟甲基糠醛。考察了反应温度、反应时间、催化剂用量、葡萄糖用量对5-羟甲基糠醛收率的影响。结果表明,最佳工艺条件:反应温度190℃,反应时间43 min,催化剂用量0. 3 g,葡萄糖用量0. 15 g,在此条件下,5-羟甲基糠醛的收率44. 7%。     

维生素C催化合成糠醛1,2–丙二醇缩醛

以维生素C为催化剂,糠醛和1,2–丙二醇为原料,催化合成了糠醛1,2–丙二醇缩醛。详细探索了醛醇摩尔比、催化剂用量、带水剂用量、带水剂种类、反应时间等因素对收率的影响。得出了维生素C催化合成糠醛1,2–丙二醇缩醛最佳工艺条件:以糠醛0.2 mol为标准,醛醇摩尔比1∶1.3,带水剂用量10 m L,维生素C用量0.8 g,反应时间90 min,反应温度为回流温度,在此最佳条件下,得出缩醛的收率为75.86%。该工艺具有操作简单,反应条件温和,产品易于分离等优点。     

常压两相法制糠醛的工艺条件研究

本实验主要研究常压两相法制备糠醛的最佳工艺,通过对催化剂硫酸的浓度、有机相与无机相体积比、助剂氯化钠加入量、反应时间等实验条件的考察,来确定最佳工艺条件。最佳反应条件为:硫酸的浓为3 mol/L、有机相与无机相体积比为0.8、助剂氯化钠的用量为17.5 g(75mL硫酸溶液),反应时间4 h。最佳反应条件下,糠醛的收率可达到62.25%。     

文冠果壳渣联产糠醛及高吸附性能活性炭

以文冠果壳为原料,利用硫酸法制备糠醛,在单因素实验的基础上采用正交试验法研究硫酸浓度(A)、料液比(B)、蒸馏温度(C)、蒸馏时间(D)对糠醛得率的影响。糠醛渣采用微波辐照氯化锌法制备活性炭,通过正交试验法研究氯化锌浓度(A)、浸渍时间(B)、微波功率(C)、辐照时间(D)对活性炭得率、碘吸附值、亚甲基蓝吸附值的影响。结果显示,制备糠醛的最佳工艺条件为:硫酸浓度为2.0 mol/L,料液比为1∶6,反应温度为160℃,反应时间为2 h,在该条件下糠醛的产率为17.2%;制备活性炭的最佳工艺条件为:氯化锌质量分数为40%,浸渍时间为24 h,微波功率为700 W,辐射时间为5 min,在此条件下,文冠果壳木糖渣活性炭的得率为53.35%,碘吸附值与亚甲基蓝脱色力分别达到983.17 mg/g和165.59 m L/g。     

混酸水解纤维素的工艺研究

研究了盐酸质量分数、液固比、温度和时间对纤维素水解的影响,并对水解工艺条件进行优化。实验结果表明,水解的最佳工艺条件为:盐酸在混酸中的质量分数为4%,混酸与纤维素液固比为24∶1(g/g),反应温度65℃,反应时间8 h。在此条件下,总还原糖得率为25%,葡萄糖得率为16.7%,纤维低聚糖的得率为8.3%。     

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。