双酶协同水解微波改性木薯淀粉的动力学研究

研究了α 淀粉酶和葡萄糖苷酶协同水解微波改性木薯淀粉的动力学,在单一水解体系中,α 淀粉酶和葡萄糖苷酶对微波改性淀粉颗粒的降解遵循Michaelis Menten方程,葡萄糖苷酶的米氏常数Km=18 718mol/mL,最大反应初速度Vmax=0 745mol/(mL·min),α 淀粉酶的米氏常数Km=88 334mol/mL,最大反应初速度Vmax=1 039mol/(mL·min)。葡萄糖对反应体系具有竞争性抑制剂的作用,其抑制常数Ki=9 656×10-4mol/mL。双酶协同作用的水解效率比单酶作用的水解效率高。     

脂肪酶水解植物油及动力学参数测定

以酯解理论为基础,通过均匀设计法研究游离酶水解植物油的最佳工艺条件。试验结果表明:游离酶最佳催化条件为pH9.6、33℃、底物浓度25％,其动力学参数Vm和Km值分别为5.56(μmol/ml·min)和6.2×10~(-2)(V/V)。     

微波辐射下双酶催化淀粉水解的动力学研究

以玉米淀粉为反应底物,研究了α-淀粉酶和糖化酶分别在微波辐射和水浴加热条件下水解玉米淀粉的动力学特性。考察了pH、温度、底物质量浓度、酶用量对玉米淀粉水解反应速率的影响。结果表明,微波辐射条件下的平均反应速率比水浴加热提高了20%以上。以米氏方程为基础,研究了两种加热方式下的米氏常数Km、最大反应速率νm和抑制常数Ki。结果表明,微波辐射下α-淀粉酶的Km=3 922.76 g/L,νm=1.72×10-3mol/(mL.min),糖化酶的Km=173.31 g/L,νm=3.289×10-5mol/(mL.min);水浴加热条件下α-淀粉酶的Km=312.03g/L,νm=1.21×10-4mol/(mL.min),糖化酶的Km=16.14 g/L,νm=3.89×10-6mol/(mL.min);微波辐射下糖化酶的抑制常数(Ki)低于水浴加热的抑制常数。     

马铃薯酪氨酸酶体外筛选美白剂测定体系的建立

以儿茶酚为底物,研究了自制马铃薯酪氨酸酶的动力学性质,建立了利用马铃薯酪氨酸酶体外筛选美白剂的测定体系,测定了12种中药提取物的酪氨酸酶抑制活性。结果表明,马铃薯酪氨酸酶的适宜反应条件为:30℃、pH=6.5;以儿茶酚为底物,酶促反应产物的最大吸收波长为420 nm;马铃薯酪氨酸酶的动力学参数如下:Vmax=0.284 9 min-1;Km=5.441 2 mmol/L;在12种中药的乙醇〔φ(C2H5OH)=50%〕提取液中,生药质量浓度达到2 g/L时,红花(Carthamus tinctorius L.)、杨梅叶(Myrica rubra S.)、黄芩(Scutellaria baicalensis G.)和绿茶(Camellia sinensis L.)相对L-抗坏血酸(ρ=0.2 g/L)的酪氨酸酶抑制率分别达到128.62%、83.64%、79.65%和66.48%,它们在美白化妆品领域有潜在的应用价值。     

草酸二乙酯水解宏观动力学研究

在65～80℃对草酸二乙酯水解生成草酸的反应宏观动力学进行了研究,得到的草酸二乙酯水解反应速率方程可表示为rc=dcc/dt=kc0.5acc1-kc1.5c k=2.117×105exp(-3.479×104/RT) k=5.273×102exp(-1.398×104/RT) 并用实验数据对模型进行了检验.     

马铃薯微孔淀粉的制备及吸附性能研究

用淀粉糖化酶、α-淀粉酶及普鲁兰酶水解马铃薯淀粉制备一种具有吸附功能的马铃薯微孔淀粉载体。研究表明,淀粉糖化酶对马铃薯淀粉作用力最强,糖化酶水解淀粉制备马铃薯微孔淀粉的最佳工艺条件是：温度45℃,pH值4,酶用量为1％,时间24h。微孔淀粉对色素、水溶性维生素、油脂的吸附能力高于原淀粉。     

硝酸氧化淀粉制备草酸动力学研究

探讨利用硝酸与淀粉在酸性及催化剂与助催化剂存在条件下合成草酸的反应机理,提出了在酸性条件下由淀粉水解成葡萄糖,葡萄糖进一步被硝酸氧化成草酸的宏观动力学模型。该过程分为2步:淀粉水解过程为表观一级反应,动力学方程为CA=CA0exp(-k1t);葡萄糖氧化过程通过稳态法处理后,动力学方程为CE=CB0(1-e-k2t)。通过实验计算出其中参数k1=0.082min-1;k2=0.0050min-1。研究结果为报废液体推进剂红烟硝酸的再利用提供了理论与技术支持。     

HPLC法研究C.I.Reactive Red 24水解反应动力学

采用反相离子对高效液相色谱法(HPLC)研究了C.I.Reactive Red 24 水解反应动力学.当染料溶液中羟基过量时, 可视为一级反应; -d[A]/dt=k[A].在pH=13时, ln(A0/A)与反应时间t呈线性关系; 95℃时的水解反应速率常数K(0.0599)比70℃时的k(0.0101)高约4倍; pH为13时, 反应速率常数K(5.99×10-2)比8.5时的k(4.8×10-3)高约11.5倍; pH值每升高1, 染料的水解速率相应提高1.5倍.     

磁性壳聚糖复合微粒固定化SOD的研究

制备了磁性壳聚糖复合微粒(Fe3O4/CS),并以Fe3O4/CS为载体固定了超氧化物歧化酶(Superoxide Dismutase,SOD)。研究了温度、pH、储存时间、操作次数等对固定化SOD和游离SOD活性的影响。研究结果表明,固定化SOD的热稳定性、pH稳定性、储存稳定性等性能明显优于游离SOD,固定化SOD的操作稳定性良好。研究了固定化SOD和游离SOD的半衰期t1/2和动力学性质。固定化SOD的半衰期t1/2,1=35.7 d,游离SOD的半衰期t1/2,2=8.8 d;固定化SOD的米氏常数Km,1=0.04 mmol/L,最大反应速率Vm,1=40.19 mmol/min,游离SOD的米氏常数Km,2=0.19 mmol/L,最大反应速率Vm,2=85.76 mmol/min。     

Novozym435催化不对称水解3-(4-氟苯基)-戊二酸二甲酯的动力学研究

对Novozym 435在以甲基叔丁基醚(MTBE)为助溶剂的水相体系中不对称水解3-(4-氟苯基)-戊二酸二甲酯(3-DFG)的动力学进行了研究。考察了摇床转速、酶浓度、底物浓度、产物浓度等因素对该水解反应的影响。结果表明该水解反应的最佳转速为200 r?min?1,内扩散的影响可忽略。底物3-(4-氟苯基)-戊二酸二甲酯和产物3-(4-氟苯基)-戊二酸单甲酯(3-MFG)对Novozym 435的催化水解活性不存在抑制作用。此外,该反应受副产物甲醇的竞争性抑制,通过非线性回归求得该体系相应的动力学参数值:米氏常数Km值为0.24 mol?L?1,抑制常数Ki值为0.39 mol?L?1,最大反应速度Vmax值为2.39 mmol?L?1?h?1。     

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。