汽喷玉米秸杆纤维素酶水解的研究

研究了纤维素酶对汽喷玉米秸杆的水解作用，结果表明，利用纤维素酶直接酶解汽喷玉米秸秆，当底物玉米秸杆与水的质量比（即固液比，下同）为１：１０，酶用量８．８ＦＰＩＵ／ｇ玉米秸秆时，酶解４８小时，酶解得率达７０．０％。同时，还提出了汽喷玉米秆酶解木质素的综合利用的途径。     

离子液体[BMIM]Cl处理汽爆活化玉米秸秆及酶解

为了提高玉米秸秆酶解还原糖产率,利用蒸汽爆破法活化玉米秸秆原料,并利用离子液体[BMIM]Cl进行处理,考察了汽爆压力和维压时间对处理后物料酶解还原糖产率的影响。结果表明,汽爆压力2.6 MPa,维压时间90 s下汽爆活化秸秆原料,[BMIM]Cl处理后,酶解24 h后还原糖产率较汽爆活化后物料提高了84.03%,较原料提高了286.83%。秸秆化学组分分析表明,[BMIM]Cl处理后物料纤维素质量分数增加了64.86%,X射线衍射(XRD)与扫描电镜(SEM)分析表明,其晶形结构转变为无定形结构,更有利于纤维素酶与底物作用。说明汽爆活化[BMIM]Cl处理能显著提高玉米秸秆的酶解还原糖产率。     

响应面法优化水/醇处理后汽爆玉米秸秆酶解

为了提高水/醇处理后汽爆玉米秸秆的酶解还原糖产率,对其酶解条件进行了优化。通过响应面优化法确定了底物质量浓度为53.28 g/L,纤维素酶用量为53.32 FPU/g,酶解时间为60.45 h时,还原糖产率可达672.36mg/g,与秸秆物料及汽爆后物料相比,酶解还原糖产率分别提高了170.46%和28.97%。化学组分及结构形貌分析表明,汽爆水/醇处理后物料纤维素含量显著增加,物料相对结晶度增高,其结构更有利于纤维素酶分子的吸附。     

纤维素酶水解玉米秸秆的影响因素研究

考察了预处理方式、纤维素酶加量、初始葡萄糖含量等因素对玉米秸秆酶解效果的影响。结果表明,经过稀酸和蒸汽爆破预处理玉米秸秆的酶解得率分别为97.0％和91.0％,均高于未经预处理玉米秸秆;对蒸汽爆破玉米秸秆,纤维素酶加量与酶液的滤纸酶活不成正比关系,纤维素酶加量越多,平均葡萄糖生成速率(GR)越大;葡萄糖对纤维素酶水解具...     

响应面法优化水/醇处理后汽爆玉米秸秆酶解的研究

为了提高水/醇处理后汽爆玉米秸秆的酶解还原糖产率,对其酶解条件进行了优化。通过响应面优化法确定了底物浓度为53.28g/L,纤维素酶用量为53.32FPU/g,酶解时间为60.45h时,还原糖产率可达672.36mg/g,与秸秆物料及汽爆后物料相比,酶解还原糖产率分别提高了179.21%和37.29%。化学组分及结构形貌分析表明：水/醇处理后物料纤维素含量显著增加,X射线衍射(XRD)和扫描电镜(SEM)结果表明经过水/醇处理后物料相对结晶度增高,但结构更有利于纤维素酶分子的吸附。     

玉米秸秆氨化汽爆处理及其固态发酵

在加氨条件下对玉米秸秆进行了汽爆处理(简称氨化汽爆)和固态发酵. 结果表明: 氨化汽爆同样可使秸秆中的半纤维素降解,并使玉米秸秆的酶解率提高到42.97%, 同时可使秸秆的有机氮含量提高1.27倍. 利用氨化汽爆秸秆进行固态发酵,可提高蛋白含量到23.45%,比不加氨汽爆的玉米秸秆提高了1倍. 而加过氧化氢的氨化汽爆不利于微生物发酵.     

汽爆玉米秸秆发酵丁醇的酶解工艺优化

为了提高秸秆酶解后的还原糖浓度和酶解液发酵后的丁醇产量,研究了不同因素对汽爆玉米秸秆酶解的影响,优化汽爆玉米秸秆秸秆发酵丁醇的酶解工艺。结果表明汽爆玉米秸秆的最佳酶解工艺为:反应温度50℃、原始底物浓度15%(wt)、酶用量60 IU·(g底物)-1、酶解时间48 h、搅拌器转速100 r·min-1。通过考察分步加料方式,三次加料方式最高表观黏度和反应后期表观黏度都低于两次加料的方式,而其糖浓度则略高于两次加料方式。当底物从原始浓度15%(wt)分三次加入到25%(wt)时,还原糖浓度、丁醇产量分别为89.23、9.82 mg·mL-1,分别增加了58.63%、44.20%。     

高效协同酶解中性汽爆玉米秸秆的工艺优化

玉米秸秆是我国主要的农业废弃物之一,在木质纤维素乙醇领域具有广阔的应用前景。而玉米秸秆预处理和酶法糖化成本过高是目前工艺中的重点和难点之一。从4种纤维素降解酶制剂中优选出对中性汽爆玉米秸秆有最佳协同效果的木霉和黑曲霉纤维素酶制剂（6∶4体积比混合）。在此基础上,评估了木聚糖酶、β-葡萄糖苷酶、β-葡聚糖酶、漆酶、锰过氧化物酶等酶制剂,聚乙二醇-4000、吐温-80、牛血清白蛋白等非酶因子对糖化效率的影响,得到了一组高效协同降解汽爆玉米秸秆的复合酶体系,并获得了适宜的糖化工艺。结果表明,以每克中性汽爆预处理的玉米秸秆为底物,加入10FPU木霉/曲霉混合酶液,并添加1000IU的木聚糖酶和0.05 g PEG4000,于50℃/150 r·min^-1相似文献   

醇酸体系分离木质素对酶解性能的影响

为提高生物质纤维素酶解性能,采用乙二醇耦合对甲基苯磺酸(EG-PTSA)法对玉米秸秆进行预处理,考察了温度、对甲基苯磺酸(PTSA)质量分数、反应时间对酶解性能的影响,并通过扫描电镜(SEM)、X射线衍射(XRD)和傅里叶变换红外光谱仪(FTIR)对预处理前后的样品进行表征分析。结果表明:在对甲基苯磺酸质量分数2.0%、100℃、60 min下,木质素脱除率为83.2%,纤维素保留率为83.5%;同时,酶解纤维素的葡聚糖产率从23.8%提高至71.4%(5 FPU/g),比原始玉米秸秆的酶解效率(23.8%)高出近3倍。SEM、XRD和FTIR分析表明,玉米秸秆经EG-PTSA预处理后,木质素、半纤维素大量脱除打破了秸秆纤维素致密结构,增加了纤维素酶的可及性,提高了酶解性能,是一种简单、高效且有前景的预处理方法。     

蒸汽爆破玉米秸秆提高酶解还原糖产率的研究

对玉米秸秆进行蒸汽爆破预处理,并对处理前后的玉米秸秆组分和结构进行了表征。酶解24 h的实验结果表明,与未处理秸秆相比,汽爆处理后样品的还原糖产率提高了97%。化学与物理分析结果表明,处理后物料半纤维素及可溶性物质质量分数减少,纤维素质量分数增加29.7%;X射线衍射仪(XRD)和扫描电镜(SEM)表明纤维素致密结构被破坏。预处理后物料酶解还原糖产率最高时汽爆工艺参数为:汽爆压力2.2 MPa,每克秸秆原料加入1 mL蒸馏水(简称液固比1 mL/g),维压时间9 min,物料颗粒度40~60目。     

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。