基于FTIR的GIS气室中SF6分解产物SO2 F2的检测

硫酰氟(SO_2F_2)气体是全封闭组合电器(GIS)中SF_6气体分解产物的重要特征组分之一,基于SO_2F_2气体成分的检测可实现高压电器设备潜伏性故障类型的识别,因此快速准确实现GIS气室中SO_2F_2组分的检测具有重要意义。采用温、压可调多次反射长光程池,基于傅里叶变换红外光谱仪(FTIR)技术建立SO_2F_2/SF_6气体实验分析平台,在高纯SF_6背景下对痕量SO_2F_2气体谱线进行交叉干扰分析,最终选取中心波长1 503 cm~(-1)(6.65μm)处作为定性依据,利用质量比混合法及动态配气仪制备4个梯度浓度SO_2F_2/SF_6标准样品,建立了定量分析的标准曲线,并对质量比混合法制备的100～400μL/L的SO_2F_2/SF_6混气样品进行浓度反演分析。结果表明:在100～400μL/L浓度范围内,校正面积拟合曲线优于校正高度拟合曲线,线性拟合常数R~20.99,可实现SO_2F_2/SF_6混气中SO_2F_2气体的快速检测,样品浓度反演结果显示误差均小于2%。该研究可提供一种SO_2F_2/SF_6混合气体制备方法,并为GIS气室中SF_6分解产物SO_2F_2含量的检测提供一种切实可行的光学方法。     

动态稀释法配制痕量一氧化氮气体标准物质的研究

建立了一套动态稀释法配制痕量一氧化氮气体标准物质的稀释系统。通过控制两个质量流量计的流量,按比例将1.00μmol/mol的NO/N₂标准气体稀释成浓度为9.9、19.8、48.4、78.2 nmol/mol的一氧化氮标准气体,并给出稀释后标准气体的相对扩展不确定度Ur=1.7%(k=2)。同比例稀释试验(99.6μmol/mol NO/N₂标准气体稀释100倍,与1.00μmol/mol NO/N₂标准气体进行比较)证明了稀释后的标准气体浓度准确可靠。结果表明本稀释系统配制的痕量一氧化氮标准气体适用于检校低量程化学发光法氮氧化物分析仪。     

环境监测用乙酸乙酯气体标准样品制备方法研究

依照GB/T 5274—2008《气体分析校准用混合气体的制备称量法》的相关要求开展了浓度水平为1μmol/mol氮气中乙酸乙酯气体标准样品的研制工作。根据乙酸乙酯的物理化学性质确定了采用两步稀释的方法进行样品制备。建立了样品的分析方法,对分析方法精密度、制备重现性及制备的线性进行了考察。针对国产普通气瓶和国产涂层气瓶开展气瓶内壁的吸附作用研究,确定采用国产涂层气瓶制备乙酸乙酯气体标准样品。结果表明,研制浓度水平为1μmol/mol氮气中乙酸乙酯气体标准样品是可行的,将继续开展时间稳定性、瓶内均匀性等内容的研究,将为相关环境监测工作提供技术支持。     

氮气分析用高准确度微量混合气体标准物质研制

介绍了氮气分析用高准确度氮中微量混合气体标准物质的研制过程,主要包括称量法制备技术、稀释气定量分析及混合气体的均匀性检验、稳定性考察等.混合气体含有氢、氧、甲烷、二氧化碳和一氧化碳5种组分,标称浓度均为2 μmol/mol,F检验和回归曲线法实验结果表明,5组分微量混合气体标准物质在压力1～ 10 MPa内,具有良好的...     

多组分异核气体红外线分析仪

IRGA-1型多组分异核气体红外线分析仪是为在线分析而设计的。能够在工业流程中连续、自动地测定混合气体中某个组分或几个组分的φ,并在不同的窗口连续地直接显示各自的体积分数(例如同时显示CO、CO_2、CH_4、NH_4、SO_2、NO等的φ值,最多可显示7种气体),测量范围可从微量级(100cm~3/m~3)到常量级。设备造价低。     

氮气中多组分挥发性有机物(VOCs)气体标准物质的气相色谱-质谱分析方法研究

本文建立了一种氮气中42组分挥发性有机物(VOCs)混合气体标准物质的分析方法。该方法通过在气相色谱-质谱联用仪上配置气体自动进样切换阀,实现了标准样品与待测样品的交替进样。使用气相色谱-质谱联用仪选择离子扫描功能,根据在线漂移补偿原理,分析了氮气中1μmol·mol-1 42组分挥发性有机物(VOCs)混合气体标准物质。研究结果表明,该方法能有效提高分析效率,重复性可达0.5%,满足气体标准物质在定值及准确分析核验的要求。     

NO_x和SO_2在Cu_2O(111)表面上同时脱除的DFT研究

采用密度泛函理论,系统研究了SO_2和NO_x在Cu_2O(111)表面上同时脱除的反应机理。计算结果表明,在Cu_2O(111)表面上,NO_2会直接与SO_2反应,进而生成SO_3和NO,反应能垒是121.372kJ/mol;SO_2与NO之间的反应是通过NO先以二聚体的形式生成N_2和O,生成的O原子与SO_2生成SO_3的过程是整个反应过程的速控步骤,能垒是139.992kJ/mol。根据以上结果总结出了Cu_2O(111)表面上SO_2和NO_x共同脱除的机理,将对研究NO_x和SO_2共同脱除提供重要的理论指导意义。     

Cr^3+掺杂对ZnGa2O4光催化性能影响的研究

试验以Ga(NO3)3·9H2O、Zn(NO3)2·6H2O、Cr(NO3)3·9H2O、Na3C6H5O7·2H2O为原料,采用水热法制备Cr^3+掺杂ZnGa2O4。通过XRD、TEM对样品的结构和形貌进行表征,通过UV-vis DRS、PL对样品进行光学性能表征,利用紫外-可见光分度计测试罗丹明B的吸光度变化情况对样品进行光催化性能检测。研究掺杂量、煅烧温度、保温时间对ZnGa2O4的影响,试验结果表明,最佳制备条件为:Cr^3+掺杂量1.0%、煅烧温度700℃、保温时间8 h。最佳条件下ZnGa1.99Cr0.01O4降解罗丹明B在60 min降解率可达97%;ZnGa1.99Cr0.01O4产氢量为446.4μmol/g,对比Zn Ga2O4产氢量为184.7μmol/g,产氢量增加。     

环境空气监测用氮气中多组分醛酮气体标准物质的研制

介绍了氮气中13组分醛酮气体标准物质的制备方法。气体标准物质的组分为甲醛、乙醛、丙烯醛、正丁醛、戊醛、2-丁酮、丙酮、丁烯醛、甲基丙烯醛、丙醛、己醛、间甲基苯甲醛和苯甲醛,标准值为1μmol/mol。根据组分的不同性质,经研究采用3步称量法来制备13组分醛酮标准气体,建立了气相色谱-质谱联用及选择扫描离子模式的分析方法,对研制的气体标准物质在气瓶中的均匀性和长期稳定性进行了考察。将研制的气体标准物质分别送至中国计量科学研究院(NIM)和中国环境监测总站(CNEMC)进行了对比测试,取得了良好的对比结果。结果表明,1μmol/mol氮气中13组分醛酮气体标准物质具有较好的均匀性和稳定性,其有效期为12个月,取得了国家二级标物证书,标物号GBW(E)083618。     

氮气中14种芳香烃混合气体标准样品的研制

介绍了氮气中14种芳香烃混合气体标准样品的制备和定值方法。气体标样的组分是苯、甲苯、乙苯、对二甲苯、间二甲苯、邻二甲苯、苯乙烯、氯苯、1,3,5-三甲苯、1,2,4-三甲苯、1,4-二氯苯、1,3-二氯苯、1,2-二氯苯、1,2,4-三氯苯,浓度水平为1μmol/mol。通过制备重现性、浓度线性关系、均匀性和稳定性的考察,气体标样在气瓶内均匀性良好,扩展相对不确定度分别为3%~7%。     

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.