钯/石墨烯/离子液体纳米复合物的过氧化氢电化学传感器

将一定比例的石墨烯(GN)与离子液体(IL)1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF6)超声混匀GN-IL,并滴涂在玻碳电极(GC)上,然后通过电沉积法在此电极上沉积钯纳米颗粒制得Pb/GN-IL/GC修饰电极。采用循环伏安法和计时电流法研究了该传感器对H2O2的电催化还原行为。结果表明,与IR修饰电极和石墨烯修饰电极相比,该电极对H2O2具有更好的电催化活性。此传感器对过氧化氢检测的线性范围为4.0×10-6~4.3×10-4mol/L,检出限为2.1×10-6mol/L。     

钯/石墨烯/离子液体纳米复合物的过氧化氢电化学传感器

将一定比例的石墨烯(GN)与离子液体(IL)1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF6)超声混匀GN-IL,并滴涂在玻碳电极(GC)上,然后通过电沉积法在此电极上沉积钯纳米颗粒制得Pb/GN-IL/GC修饰电极。采用循环伏安法和计时电流法研究了该传感器对H2O2的电催化还原行为。结果表明,与IR修饰电极和石墨烯修饰电极相比,该电极对H2O2具有更好的电催化活性。此传感器对过氧化氢检测的线性范围为4.0×10-6⁴.3×10-4mol/L,检出限为2.1×10-6mol/L。     

烷基咪唑次氯酸盐离子液体的萃取脱硫研究

合成了烷基碳链长度不同的烷基咪唑次氯酸盐离子液体,分别考察了不同条件下离子液体对模拟油品和实际油品的脱硫效果。研究结果表明,在40℃,反应时间为60 min,[C6MIM]ClO离子液体作为萃取剂,VIL∶VOil=4∶1时,对初始硫含量为1 160×10-6的模拟油品一次萃取脱硫率可达77.58%,初始硫含量为117×10-6的催化裂化汽油一次脱硫率为61.23%,初始硫含量为1 974×10-6的催化裂化柴油一次脱硫率为51.84%。     

离子液体在合成橡胶中的应用研究进展

综述了离子液体在合成橡胶的加氢反应、硫化和填料改性等方面的应用,着重总结了其在碳纳米颗粒和无机纳米颗粒填料改性中的应用。     

Pt纳米粒子/ZnO纳米管修饰的钛片葡萄糖传感器

基于钛片载Pt纳米颗粒修饰的ZnO纳米管电极制备了葡萄糖生物传感器。用电化学沉积法制备了ZnO纳米棒阵列,并用化学腐蚀法制备了ZnO纳米管。Pt纳米颗粒采用恒电位沉积法修饰在ZnO纳米管表面。用扫描电子显微镜和X-射线衍射表征了纳米Pt-ZnO/Ti修饰电极。该修饰电极在0.05 M的NaOH中对葡萄糖的催化氧化表现出很好的响应,线性范围为1×10-5～1×10-2mol/L,响应时间小于4 s,并且具有良好的重现性。     

离子液体[BMIm]NTf_2中Ni纳米颗粒的制备及其催化性能研究

微波辐射下合成了1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺([BMIm]NTf2)离子液体,并采用IR和1H NMR验证了其结构。利用化学还原法分别在水溶液和离子液体[BMIm]NTf2中制备了Ni纳米颗粒,采用XRD、TEM对其结构进行表征,并考察这两种纳米Ni颗粒在邻硝基苯催化加氢反应中的催化性能。结果表明,[BMIm]NTf2中制备的Ni纳米颗粒为面心立方结构,粒径在3～30 nm。在还原过程中,离子液体同时起到了溶剂和修饰剂的作用,在所生成的Ni纳米颗粒的表面形成了一层离子液体的修饰层,阻止了Ni纳米粒子之间的团聚;在相同条件下,[BMIm]NTf2中制备的纳米Ni颗粒的催化活性显著高于常规水性介质中制备的Ni催化剂。     

离子液体[BMIm]NTf2中Ni纳米颗粒的制备及其催化性能研究

微波辐射下合成了1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺（[BMIm]NTf2）离子液体,并采用IR和1HNMR验证了其结构。利用化学还原法分别在水溶液和离子液体[BMIm]NTf2中制备了Ni纳米颗粒,采用XRD、TEM对其结构进行表征,并考察这两种纳米Ni颗粒在邻硝基苯催化加氢反应中的催化性能。结果表明,[BMIm]NTf2中制备的Ni纳米颗粒为面心立方结构,粒径在3—30nm。在还原过程中,离子液体同时起到了溶剂和修饰剂的作用,在所生成的M纳米颗粒的表面形成了一层离子液体的修饰层,阻止了Ni纳米粒子之间的团聚;在相同条件下,[BMIm]NTf2中制备的纳米Ni颗粒的催化活性显著高于常规水性介质中制备的Ni催化剂。     

碳纳米管修饰的碳糊铁离子选择性电极的研究

以新型碳纳米管复合物修饰的碳糊铁离子选择性电极被研制出来。电极对Fe3+呈现近Nernst电位响应性能,电极响应的线性范围为1.8×10-8～1.0×10-1mol/L,斜率为26.3 mV/decade,检测下限为0.9×10-9mol/L。电极Fe3+具有良好的选择性,其响应时间为25 s。将此离子选择性电极应用于Fe3+的回收率实验,结果令人满意。     

离子液体超声辅助制备纳米CdSe及其荧光性能

采用离子液体超声辅助合成了CdSe纳米颗粒,用荧光分光光度计对纳米颗粒进行了表征。XRD结果显示,产物具有立方晶系结构,随着反应时间的增加,产物的结晶度逐渐提高。讨论了[Bmim]OH-H2O离子液体、反应时间对产物的形貌以及荧光性能的影响。在1 mL[Bmim]OH-H2O溶液中,超声反应1 h,所得产物的直径约为30～60 nm,荧光强度达到54 a.u.以上。离子液体在纳米颗粒表面形成一种保护膜,有效地阻止了颗粒间的团聚,提高了产物的荧光性能。     

碳化钼/碳纳米片复合材料的制备及析氢性能研究

为了解决Pt基催化剂成本较高的问题,使用电弧放电和高温碳化两步法制备了一种碳纳米片负载碳化钼纳米颗粒的非贵金属催化剂。通过X-射线粉末衍射仪(XRD)、透射电子显微镜(TEM)对催化剂的晶体结构、形貌、碳化钼颗粒尺寸进行了表征分析。结果表明,700℃碳化得到的碳化钼/碳纳米片复合催化剂(Mo_2C/CNS)在酸性电解质溶液中表现出优异的析氢性能。在-10 mA/cm²的电流密度下过电位为-221 mV,塔菲尔(Tafel)斜率为68.1 mV/dec,并且1 000圈CV扫描后过电位没有明显下降,显示出优异的稳定性。     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.     

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.