金银花绿原酸的酶解工艺及抗氧化活性研究

纤维素酶酶解法提取金银花绿原酸的最佳工艺条件为:提取温度55℃,酶用量(对底物浓度)0.6%,提取时间60 min,乙醇体积分数70%,金银花绿原酸提取率为4.85%。体外抗氧化研究结果表明,金银花绿原酸具有较强的抗氧化能力,其抗氧化能力与绿原酸浓度在一定范围内呈线性关系。金银花绿原酸添加量0.5 mg/m L时,对OH·的清除率达61.26%,IC50为0.258 6 mg/m L,比维C效果略好。添加量0.4 mg/m L时,对O2-·的清除率高达94.81%,IC50为0.128 6 mg/m L,清除效果明显优于维C。金银花绿原酸在恒温65℃下,将油脂过氧化值POV在18 d内维持在5.5 mol/g以下。     

金银花绿原酸的酶解工艺及抗氧化活性研究

纤维素酶酶解法提取金银花绿原酸的最佳工艺条件为:提取温度55℃,酶用量(对底物浓度)0.6%,提取时间60 min,乙醇体积分数70%,金银花绿原酸提取率为4.85%。体外抗氧化研究结果表明,金银花绿原酸具有较强的抗氧化能力,其抗氧化能力与绿原酸浓度在一定范围内呈线性关系。金银花绿原酸添加量0.5 mg/m L时,对OH·的清除率达61.26%,IC50为0.258 6 mg/m L,比维C效果略好。添加量0.4 mg/m L时,对O2-·的清除率高达94.81%,IC50为0.128 6 mg/m L,清除效果明显优于维C。金银花绿原酸在恒温65℃下,将油脂过氧化值POV在18 d内维持在5.5 mol/g以下。     

几种客家药膳植物的抗氧化活性研究

为利用客家地区丰富的药膳资源开发天然抗氧化剂,以总黄酮质量和DPPH清除率为指标,从溪黄草、蛇舌草、一点红、白头翁、针包草和鸡骨草中筛选出抗氧化活性较高的溪黄草。在花生油抗氧化加速试验中,添加0.05%溪黄草提取物能在6天内抑制花生油的氧化;通过D101大孔树脂的吸附、洗脱,75%乙醇洗脱液的抗氧化活性比其他浓度乙醇洗脱液的高,其对花生油的抗氧化效果明显提高,且抗氧化效果随添加量的增加而增强;添加0.05%溪黄草75%乙醇洗脱物的抗氧化效果与添加0.02%TBHQ的效果接近。     

茶儿茶素氧化聚合物抗油脂自动氧化作用的研究

用Na2 S2 O3 I2 滴定法测定了茶儿茶素氧化聚合物对猪油和豆油的抗氧化作用 ,并以茶多酚作比较。结果表明 ,在 30℃见光条件下贮存 2 5d ,相对油质量而言 ,当添加质量分数分别为0 0 0 5 %～ 0 0 2 0 %时 ,茶儿茶素氧化聚合物和茶多酚对猪油氧化的抑制率分别为 43 1%～5 7 0 %和 38 0 %～ 45 2 % ,且两者均在添加质量分数为 0 0 10 %时抗氧化活性最强 ;在 30℃避光条件下 ,茶儿茶素氧化聚合物对豆油体系也显示出同样的抗氧化效果 ;Vc和柠檬酸对儿茶素氧化聚合物具有协同增效作用 ,儿茶素氧化聚合物与Vc或柠檬酸按m(儿茶素氧化聚合物 )∶m(Vc或柠檬酸 ) =1∶1复配 ,可使其抗氧化活性增强 3～ 5倍     

B4C添加量对Al2O3-C材料性能的影响

以板状刚玉(粒度≤1、≤0.075 mm)、Al-Si合金粉(粒度为50μm)、α-Al₂O₃微粉(粒度为5μm)、鳞片石墨(粒度≤0.074 mm)和B₄C粉(粒度为20μm)为原料，硝酸镍为催化剂，酚醛树脂为结合剂制备了Al₂O₃-C材料，研究了B₄C添加量(加入质量分数分别为0、3%、6%和9%)对Al₂O₃-C材料性能的影响。结果表明：1)随着B₄C添加量的增加，试样的线变化率明显减小，常温抗折强度和耐压强度明显增大；当B₄C添加量为3%(w)时，试样经1 450℃处理后的线变化率降至0.65%,常温抗折强度和耐压强度最高，分别为28.7和57.3 MPa。2)当B₄C添加量为6%(w)时，试样经1 400℃空气气氛氧化后的氧化指数降至3.9%,抗氧化能力明显增强。     

FeCrAl基高温抗氧化陶瓷涂层抗热震性能的研究

采用陶瓷粘结相与Cr2O3制成料浆,在空气中1300℃下熔烧制备FeCrAl基高温抗氧化陶瓷涂层。研究了分散相Cr2O3的添加量和涂层厚度对试样抗热震性能的影响。结果表明:当Cr2O3的添加量为50%(质量分数,下同)、涂层厚度100μm和熔烧制度为1300℃×60min的条件下,涂层试样的抗热震次数可达16次(室温←→1200℃)。采用SEM、高温热膨胀仪等测试手段对涂层试样的组织结构及性能进行表征,揭示了涂层组织结构与抗热震性能之间的关系。     

聚苯硫醚改性方法及成型研究进展探讨

本文通过以蒙脱土纳米颗粒(MMT)与2,6-二叔丁基对甲酚(BHT)为助剂对PPS进行抗氧化改性,然后通过双螺旋挤出机进行混炼、挤出成型,探究了不同抗氧化剂BHT添加量(1,2,3,5和10 wt.%)对PPS抗氧化改性效果的影响。实验结果表明,MMT和BHT均能有效地增强PPS的抗氧化性;随着抗氧化剂BHT添加量增加,抗氧化性能先升高后降低,在BHT为3 wt.%的改性PPS时氧化前后拉伸强度保持率最高92%。     

粉状脲醛树脂的制备及性能优化

采用M(三聚氰胺)对UF(脲醛树脂)改性,并经高温干燥过程制备粉状MUF(三聚氰胺改性脲醛)树脂,并对M掺量、M两次添加比例、树脂固含量与固化剂影响MUF树脂性能规律进行探究。结果表明:随三聚氰胺添加量增加,MUF粉状树脂甲醛释放量逐渐降低,胶接强度先增后降,并在w(M)=5%(相对于UF总质量而言)时达到最佳;当M两次添加比例m(M_1)∶m(M_2)=1∶4,树脂胶接强度最大,粉状树脂颗粒均匀,分散性较好;液体MUF树脂固含量为30%时,干燥后制备的粉状树脂胶接强度最大、甲醛释放量最低;m(固体固化剂)∶m(粉状树脂)=15∶100比例混合时,MUF树脂胶粘剂综合性能最佳。     

分散剂对含Al_2O_3凝胶粉的Al_2O_3-MgO质浆料流变特性的影响

以板状刚玉细粉(≤0.043 mm)、电熔镁砂细粉(≤0.088 mm)、仅α-Al2O3微粉(d50=0.1m)和Al2O3凝胶粉(<100 nm)为原料,按m(板状刚玉细粉):m(电熔镁砂细粉):m(α-Al2O3微粉):m(Al2O3凝胶粉)=6:2:1:1的基本配比配制成含水量(质量分数)为16.7%的浆料,研究了分别添加不同量柠檬酸钠、三聚磷酸钠、六偏磷酸钠、三聚氰胺甲醛树脂磺酸盐(SM)、β-萘磺酸盐与甲醛缩合物(FDN3000)、分散氧化铝(ADS、ADW)、聚乙二醇基聚合物(FS10)、聚羧酸脂基聚合物(FS20)对浆料流变特性的影响.结果表明:(1)这些分散剂(除六偏磷酸钠外)及其加入量对Al2O3-MgO质浆料的流变特性有较大影响,并且均存在最适宜的加入量.(2)添加FS10、FS20、ADW、FDN3000时,在其最佳添加量附近,浆料的流变特性接近牛顿流体,在其他添加量下浆料的流变特性接近假塑性流体;添加ADS、SM、柠檬酸钠或三聚磷酸钠时,浆料的流变特性接近假塑性流体.(3)FS10对Al2O3-MgO质浆料的分散效果较好,六偏磷酸钠则不能分散Al2O3-MgO质浆料.     

B4C和Si组合抗氧化剂对低碳MgO-C砖抗氧化性能的影响

以电熔镁砂、鳞片石墨、炭黑为主要原料,热塑性酚醛树脂为结合剂,六次甲基四胺为固化剂,硅粉(w(Si)>80%,粒度<0.074mm)和碳化硼(d90=36.5μm)为组合抗氧化剂,混合均匀后,在200MPa下压制成36mm×36mm的低碳MgO-C试样,经200℃烘干24h后,分别在600℃、1000℃和1400℃保温2h进行氧化试验,通过脱碳层面积的比较,研究B4C和Si组合抗氧化剂对低碳MgO-C砖抗氧化性能的影响。结果表明:(1)硅粉加入量为3%时,在600℃和1000℃,碳化硼加入量为0.5%的试样的抗氧化性能较好;在1400℃时,试样的抗氧化性能随碳化硼加入量的增大而增强,即碳化硼加入量为0.7%的试样抗氧化性能最好。(2)碳化硼加入量为0.5%时,在600℃和1000℃,硅粉加入量为3%与5%的试样的抗氧化性能相差不大,均比硅粉加入量为1%的试样好;而在1400℃,试样的抗氧化性能随硅粉加入量的增大有明显改善,即硅粉加入量为5%的试样抗氧化性能最好。(3)综合在不同温度下的氧化试验结果,认为含0.5?C和3%Si组合抗氧化剂的低碳镁碳材料的抗氧化性能最好。     

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。