溴代烷烃与活性氮的反应发光研究

在流动余辉装置上, 利用N₂空心阴极放电制备活性氮, 研究了活性氮与溴代烷烃(CHBr₃、CH₂Br₂、C₂H₅Br、C₄H₉Br) 反应的化学发光.上述所有反应中, 在550～750 nm波段均观察到了较强的NBr (b¹Σ+→X³Σ^-)跃迁发射谱. 同时在活性氮与CHBr₃和CH₂Br₂的反应中, 在流动管下游还观察到了CN (A²π, B²π→X²Σ⁺)的发射谱. 验证性的实验表明, 激发态NBr (b¹Σ⁺)是由二步过程形成: N(⁴S)与溴代烷烃反应生成NBr (X³Σ^-), 再通过N₂ (A ³Σ_u⁺)分子能量转移到激发态NBr (b¹Σ⁺); 而激发态的CN是通过N(⁴S) + CBr→CN(A, B) + Br过程形成的.     

不同温度下VUV光激发的Pr3+离子的发光性质

The luminescent properties of Pr³⁺-doped LaB₃O₆, SrAl₁₂O₁₉, SrB₄O₇ and NaYF₄ in the vaccum ultraviol-et (VUV) range at different temperatures were investigated under the excitation of high-energetic synchrotron radiation. For Pr³⁺ ions in LaB₃O₆, SrAl₁₂O₁₉ and SrB₄O₇, only the parity-forbidden ¹S₀→4f² transitions were observ-ed in the emission spectra at relatively low temperature; but the parity-allowed 4f5d→4f² transitions appeared simultaneously when the temperature was high enough. And the intensity of broad 4f5d→4f² emission increased relative to the intensity of ¹S₀→4f² emissions with increasing temperature. Then the thermal equilibrium model of energy levels was employed to the lowest 4f5d state and ¹S₀ state of Pr³⁺ in the three hosts. The calculated curves were in good agreement with the experimental values, indicating the occurrence of the thermal excitation from ¹S₀ state to 4f5d states at high temperatures when the lowest 4f5d state lies higher than ¹S₀ state and the photon energy is high enough.     

Ni-Co双金属催化剂上沼气重整制氢机理

用传统湿式浸渍法制备了La₂O₃掺杂的商业γ-Al₂O₃负载的沼气重整催化剂Ni-Co/La₂O₃-γ-Al₂O₃, 并用程序升温加氢(TPH)、程序升温氧化(TPO)、程序升温表面反应(TPSR)、程序升温脱附(TPD)及脉冲实验对催化剂进行了表征. 结果表明, 沼气重整过程中Ni-Co/La₂O₃-γ-Al₂O₃催化剂上的表面碳物种主要来源于CH₄的裂解, CO₂的贡献很小. CH₄裂解能够产生三种活性不同的碳物种, 即C_α、C_β与C_γ. 随着反应的进行, C_α物种减小而C_β与C_γ物种增加, 且C_γ物种能够转变为惰性的石墨碳. 重整反应过程中CH₄与CO₂的活化能相互促进. 催化剂表面的O物种与C反应生成CO或与CH_x反应生成CH_xO再分解为CO与吸附态的H物种, 可能是Ni-Co/La₂O₃-γ-Al₂O₃催化剂上沼气重整的速率控制步骤.     

Tm3+/Er3+/Ho3+共掺SiO2-Bi2O3-AlF3-BaF2玻璃发光性能

采用高温熔融法制备了Tm³⁺/Er³⁺/Ho³⁺共掺的铋硅酸盐50SiO₂-40Bi₂O₃-5AlF₃-5BaF₂玻璃。研究了在808 nm激光器（Laser Diode）激发下Tm³⁺/Er³⁺/Ho³⁺共掺的铋硅酸盐在2 060 nm处的发光性能,同时测试及分析了该铋硅酸盐玻璃的差热特性、吸收光谱及荧光光谱。根据吸收光谱以及Judd-Oflet理论,计算了Ho³⁺的Judd-Oflet强度参数Ω_t（t=2,4,6）以及Tm³⁺/Er³⁺/Ho³⁺相应的吸收截面。铋硅酸盐玻璃中,Tm₂O₃、Er₂O₃和Ho2O3掺杂浓度分别为0.75%、1.0%和0.5%时,2 060 nm处Ho³⁺∶⁵I₇→⁵I₈发射峰强度达到最大。对Tm³⁺/Er³⁺/Ho³⁺ 3种离子的光谱性质和离子间可能存在的能量传递也做了分析。Ho³⁺在1 953 nm处的最大吸收截面σ_abs为9.08×10^-21 cm²,在2 060 nm处的最大发射截面σem为11.68×10^-21 cm²,辐射寿命τ_mea为2.75 ms,具有良好的增益效应σ_emτ（3.212×10^-20 cm^-2·ms）。     

红色长余辉荧光粉Ca2Zn4Ti16O38:Pr3+的水热辅助合成及发光性质

采用水热法辅助合成了纯相Ca₂Zn₄Ti₁₆O₃₈:Pr³⁺荧光粉,初始n_Ca:n_Zn:n_Ti=2:4.1:15,煅烧条件为1 050 ℃空气气氛烧结5 h.并以X射线衍射、扫描电镜、紫外可见漫反射光谱和荧光光谱表征了样品的物相组成、微观形貌和光谱性质.合成的荧光粉在高温煅烧后仍较好地保持了球形的微观形态,优化的Pr³⁺掺杂浓度为0.015.Ca₂Zn₄Ti₁₆O₃₈:Pr³⁺荧光粉在471 nm波长激发下发射红光,发射谱通过高斯分峰拟合得到位于605、620和645 nm的3个发射峰,分别对应于Pr³⁺的¹D₂→³H₄,³P₀→³H₆和³P₀→³F₂跃迁.在471 nm波长激发下,Ca₂Zn₄Ti₁₆O₃₈:Pr³⁺的614 nm红光发射表现出超长余辉特性,表明该荧光粉是一种能被可见光有效激发的红色长余辉荧光粉.     

掺镍型层状LixNiyMn1-yO2正极材料的合成与电性能研究

A kind of cathode material of layered Li_xNi_yMn_1-yO₂ characterized with the O2 type has been synthesized by a simple method. Its precursor Na_xNi_yMn_1-yO₂ has been prepared from manganese dioxide， nickel hydroxide and sodium carbonate at high temperature in air and quickly cooled in cold water， then it has been exchanged by the melted LiNO₃ at 300～400℃ in air. The effects of calcine-temperature for the precursors and its compositions (the content of Na and Ni) on the electrochemical properties of the material Li_xNi_yMn_1-yO₂ have been investingated by XRD and electrochemical tests. The results show that the sample Li_0.7Ni_0.3Mn_0.7O₂， has the best electrochemical properties which shows only one charge-discharge potential stage of 2.8～3.0V and has a high specific capacity over 180mAh·g^-1 cycled between 2.0～4.20V. A significant structure transformation to the spinal-type phase has not been found in the charge-discharge cycling and the discharge specific capacity around 165mAh·g^-1 has re-mained after the 20th cyclings for the material.     

C2H4在Fe3C(100)表面吸附及脱氢裂解的密度泛函理论研究

采用自旋极化密度泛函理论和周期平板模型,对C₂H₄在铁基费托合成催化剂活性相之一Fe₃C（100）表面从热力学和动力学两个方面分析了C₂H₄在Fe₃C（100）表面进行脱氢和裂解反应的竞争性。结果表明,C₂H₄在Fe₃C（100）表面的μ-bridging吸附比π、di-σ吸附更加稳定;C₂H₄与Fe₃C（100）面的相互作用导致C₂H₄的C原子部分发生重新杂化（sp²→sp³）,使C原子呈近四面体结构。在Fe₃C（100）表面C₂H₄易于发生脱氢反应,C-C键裂解反应不具有竞争性。亚乙烯基CCH₂和乙烯基CHCH₂是Fe₃C（100）表面最丰的C₂物种,或是C₂H₄参与链增长的主要单体形式。     

脉冲辐解研究葛根素对自由基的清除活性

采用脉冲辐解技术, 研究了葛根素(puerarin, 一种异黄酮)对二氧化氮自由基(NO₂^•)、一氧化氮自由基(NO^•)和羟基自由基(OH^•)的清除活性. 葛根素与NO₂^•和NO^•反应产生的瞬态吸收峰都在340 nm, 该吸收峰归结为瞬态产物puerarin-4-O^•; 葛根素与OH^•反应产生了较宽的瞬态吸收光谱(300～750 nm), 该谱图归结为puerarin-2-O^•, puerarin-4-O^•和[puerarin-OH]^•瞬态吸收的叠加. 另外, 葛根素与NO₂^•, NO^•和OH^•反应的速率常数分别为2.6 × 108, 1.7 × 10⁸和3.9 × 10⁹ L·mol^-1·s^-1.     

核壳结构的Co3O4@δ-MnO2/Pt作为锂氧电池高效催化正极

通过简易、可控的水热方法在泡沫镍基体上直接生长了核壳结构的阵列型Co₃O₄@δ-MnO₂/Pt正极。阵列电极有利于电极的润湿、氧气的传输和Li₂O₂的负载。Co₃O₄@δ-MnO₂/Pt正极对氧还原和氧析出反应具有高的催化性能,可促使Li₂O₂依附Co₃O₄@δ-MnO₂/Pt阵列生长,从而保持阵列结构。该生长行为有利于Li₂O₂在充电时分解。以Co₃O₄@δ-MnO₂/Pt为催化正极的锂氧电池显示出高的容量（在电流密度100 mA·g^-1时容量为2 480 mAh·g^-1）,以及长的循环寿命（容量限定在500 mAh·g^-1时,在200 mA·g^-1电流密度下,可循环65次）,该性能超过了使用Co₃O₄或Co₃O₄@δ-MnO₂催化剂的电池。     

表面相变及Pt负载的BiOBr纳米片的协同光催化效应

通过热处理手段考察了BiOBr纳米片的表面相变过程。通过XRD,Raman,SEM,TEM,UV-Vis-DRS等手段对不同热处理温度下样品的结构进行表征。结果表明,高温热处理下（≥400℃）,BiOBr相向Bi₂₄O₃₁Br₁₀相转变,可形成BiOBr/Bi₂₄O₃₁Br₁₀异质结。通过气相乙醛的降解,并与商用P₂₅TiO₂做比较来评估催化剂的光催化性能,测得活性顺序为：P₂₅TiO₂>BiOBr>BiOBr/Bi₂₄O₃₁Br₁₀。能带结构分析可知BiOBr与Bi₂₄O₃₁Br₁₀间形成I型异质结不利于电荷分离,因而活性降低。然而,当同样条件下于上述催化剂表面负载Pt后,测得光催化活性顺序为：（BiOBr/Bi₂₄O₃₁Br₁₀）-Pt> BiOBr-Pt >P25 TiO₂-Pt。（BiOBr/Bi₂₄O₃₁Br₁₀）-Pt的最高活性归因于BiOBr/Bi₂₄O₃₁Br₁₀异质结与Pt负载的协同分离光生载流子过程,即与BiOBr/Bi₂₄O₃₁Br₁₀界面的光生空穴转移,BiOBr/Pt及Bi₂₄O₃₁Br₁₀/Pt界面的光生电子转移、累积及开启双电子还原O₂的一系列过程有关。     

Some possibilities for the immobilization of enzymes in poly(vinyl acetate-co-ethylene) tubes

The inside surface of poly(vinyl acetate-co-ethylene) tubes was coated with poly(vinyl alcohol) in the absence as well as in the presence of terephthalaldehyde as crosslinking agent. A hydrophilic inside tube surface was obtained, which was modified by reaction with 2, 4, 6-trichloro-s-triazine resp. with 2-(3-aminophenyl)-l,3-dioxolane. The latter method gave reactive tube supports after diazotization resp. after activation with glutardialdehyde. Furthermore, the amino derivative could be reacted with enzyme aggregates formed by reaction of glucose oxidase with 4-(2,3-epoxypropoxy)-benzaldehyde. Trypsin and glucose oxidase were immobilized onto the activated inside tube surfaces, and the properties of the immobilized enzymes were studied. The flow patterns of tube-immobilized trypsin were studied. The application of tube-immobilized glucose oxidase for automated glucose analysis was tested.     

Ring opening of epoxides with alcohols using Fe(Cp)2BF4 as catalyst

Fe(Cp)₂BF₄ is an efficient catalyst for the alcoholysis of aromatic, aliphatic, and cyclic epoxides giving excellent yields of the corresponding β-alkoxy alcohols under ambient conditions. The methanolysis of styrene oxide using Fe(Cp)₂BF₄ as a catalyst (5 mol %) gave excellent yield of 2-methoxy-2-phenylethanol with complete regio-selectivity. The ring opening of cyclic epoxides gave 77–97% yields of trans-β-methoxy alcohols, in 0.5–6 h. The use of 1,2-epoxyhexane and 1,2-epoxydodecane as substrates gave both regioisomers in excellent yields. The first order rate of reaction with respect to catalyst was observed for the kinetics of ring opening of 1,2-epoxyhexane with methanol.     

Electrochemical Redundant Microsensor Arrays for Glucose Monitoring with Patterned Polymer Films

Redundant microsensor arrays for glucose sensing were fabricated using photopolymerization of poly(ethylene glycol) diacrylate (PEG‐DA) with 2‐hydroxy‐2‐methyl phenyl‐propanone as photoinitiator to encapsulate the enzyme glucose oxidase. Silicon micro fabrication technologies were used to fabricate microelectrode sensor arrays on flexible polyimide sheets. These microarray sensors were individually addressable as observed using square‐wave voltammetry. Redox polymer, poly[4‐vinylpyridine Os(bipyridine)₂Cl]‐co‐ethylamine, was first immobilized on the electrode surface and then glucose oxidase was entrapped in PEG‐DA hydrogels. The redox polymer was found to exchange electrons with glucose oxidase in biocompatible PEG‐DA hydrogels. The entrapped glucose oxidase was found to respond linearly to glucose in solution (0–20 mM) as determined using square‐wave voltammetry.     

再生丝素和聚乙烯醇混合膜的结构、性能及其葡萄糖传感器的应用

用扫描电镜分析了再生丝素(RSF)和聚乙烯醇(PVA)混合膜的形貌结构,并测定了其吸水性和机械强度,用RSF和PVA的混合材料把葡萄糖氧化酶固定在玻碳电极表面,制成电流型葡萄糖传感器,以1,4-苯醌为电子传递体,酶电极对葡萄糖有灵敏的响应,峰电流的增加与葡萄糖的浓度在10^-5～10^-2mol/L范围内有良好的线性关系。用此方法制成的葡萄糖传感器物理性能好,其有效寿命长达2个月以上。该酶电极对葡萄糖的响应时间小于20s.     

One-step electropolymeric co-immobilization of glucose oxidase and heparin for amperometric biosensing of glucose

Electropolymerization was used for the co-deposition of glucose oxidase and heparin onto metal electrode transducers. Such electropolymeric co-entrapment within a non-conducting poly(1,2-phenylenediamine) (PPD) film imparts both biocatalytic and anticoagulation activities onto the transducer, and greatly improves the performance of the sensor after exposure to whole blood. Essentially identical glucose signals are observed before and after exposure to blood samples. Scanning electron micrographs after such exposure reveal no platelet deposition or formation of a fibrin "clot". The effect of the heparin co-immobilization on the glucose response is examined. Improved biocompatibility is reported also in connection with a needle-type carbon paste biosensor configuration. The simultaneous localization of the enzyme and heparin offers great promise for simplifying the preparation of enzyme electrodes and designing biocompatible implantable glucose biosensors.     

A novel insertion reaction of epoxy compounds into phenyl ester linkages in polymer chains

The insertion reaction of various epoxy compounds such as phenyl glycidyl ether (PGE), methyl glycidyl ether, butyl glycidyl ether (BGE), and styrene oxide into the phenyl ester linkage in the polymer chain was investigated using quaternary ammonium salts as catalysts in diglyme, anisole, sulfolane, o-dichlorobenzene, or DMSO at 100–150°C. The reaction of PGE with poly[4-(4-nitrobenzoyloxy)styrene] (polymer 1a ) proceeded almost quantitatively to give the corresponding polymer using tetrabutylammonium bromide (TBAB) as catalyst in diglyme at 100°C for 24 h. The reactions of BGE with poly(4-nitrophenyl methacrylate), and copolyarylate derived from 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane and iso- and terephthaloyl chlorides also produced the corresponding polymers with 86 and 89 mol% new structural units, respectively, using TBAB in sulfolane at 150°C for 24 h. Furthermore, it was found that the degree of insertion of the epoxy compound into the ester linkage in the polymer chain was affected by the kind of epoxy compound, reaction solvent, catalyst concentration, substituent group on the phenyl ester, and structure of the polymer. Chiral polymers were also synthesized with high degrees of insertion by the reaction of chiral epoxides such as (R)-1,2-epoxyhexane, (R)-1,2-epoxyheptane, and (R)-1,2-epoxydecane with polymer 1a and poly(2,4-dichlorophenyl methacrylate) using TBAB in diglyme at 120°C for 24 h.     

Response Behavior of Amperometric Glucose Biosensors Based on Different Carbon Substrate Transducers Coated with Enzyme‐Active Layer: A Comparative Study

Carbon electrodes (glassy carbon, GC, screen‐printed carbon, SPC, and carbon fiber, CF) were used as substrate transducers to prepare glucose biosensors of different sizes and geometries, based on iron‐ruthenium hexacyanoferrate as H₂O₂ reduction mediator and glucose oxidase immobilized in a poly(1,2‐phenylenediamine) membrane. Their response behavior under hydrodynamic amperometric conditions at an operating potential of ?0.02 V vs. Ag/AgCl was studied and compared. While the GC and SPC based conventional size biosensors showed enzymatic catalysis controlled current response with nonlinear concentration dependence, the CF based micro‐biosensor exhibited, due to diffusion‐controlled current response, extended linear range calibration curves with relatively lower sensitivity and longer response times. Several preparation parameters responsible for the improvement of biosensor performance were also investigated.     

Poly(alkylene oxide) ionomers. X. Copolymerization of methyl ω-epoxyalkanoates and characterization of the polymers

Selected methyl ω-epoxyalkanoates ranging from methyl 3,4-epoxybutanoate to methyl 7,8-epoxyoctanoate were copolymerized with a number of oxiranes and with oxetane. Tetrahydrofuran did not take part in the attempted methyl ω-epoxyalkanote–tetrahydrofuran copolymerization, but acted only as the solvent. The oxirane copolymers had polymer compositions similar to the comonomer feed ratio. Oxirane comonomers used were propylene oxide (1,2-epoxypropane), butylene oxide (1,2-epoxybutane), 1,2-epoxyhexane, epichlorohydrin, and phenylglycidyl ether. The initiator system used was triethylaluminum/water/acetylacetone (1.0/0.5/1.0) in about 5 mol %. In the copolymerizations using methyl 3,4-epoxybutanoate as a comonomer, only small yields of polymer (in the range of 1 to 2%) were realized, while for methyl 4,5-epoxypentanoate the yields were generally in the range of 20 to 60%. Methyl 7,8-epoxyoctanoate copolymerized readily and gave yields of copolymers of 50 to 90%.     

Specific interaction between fluorine atoms and thiol groups accounting for higher domain purity and photostability in narrowband BHJ systems

In order to explore the role of fluorine atoms on photostability as well as morphology control of active layer in the presence of 1,4‐butanedithiol (BT), the four polymers with or without fluorine atoms in the backbones including polythieno[3,4‐b]thiophene/benzodithiophene, poly[(4,8‐bis‐(2‐ethylhexyloxy)‐benzo(1,2‐b:4,5‐b9)dithiophene)‐2,6‐diyl‐alt‐(4‐(2‐ethylhexanoyl)‐thieno[3,4‐b]thiophene‐)‐2‐6‐diyl)], poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)], and poly[4,8‐bis‐(2‐ethyl‐hexyl‐thiophene‐5‐yl)‐benzo[1,2‐b:4,5‐b0]dithiophene‐2,6‐diyl]‐alt‐[2‐(20‐ethyl‐hexanoyl)‐thieno [3,4‐b]thiophen‐4,6‐diyl] were selected for comparison. It is found that the specimens containing fluorine atoms in polymer backbones showed of higher stability after illumination for 1 h in the presence of BT additive, contributing to the higher domain purity. The specific interaction between fluorine atoms and thiol groups was demonstrated by the appearance of novel absorption peak at 2663.1 cm^?1, in addition to the broadening of peak at 2556.2 cm^?1 ascribing to S? H stretching vibration as confirmed by Fourier transform infrared (FTIR) spectroscopy. The finding may guide the accurate use of thiols as effective solvent additive in morphology and stability optimization. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 941–951     

基于蛋壳膜固定酶和纳米银膜光度法对葡萄糖的检测

利用蛋壳膜固定酶和静电作用组装纳米银膜,建立了一种新型的光度法检测微量葡萄糖.采用共价交联法在蛋壳膜上固定葡萄糖氧化酶.酶促反应产生的H_2O_2氧化纳米银导致纳米银膜吸光度减小,日光强度的变化值与葡萄糖浓度有关,据此实现了对葡萄糖的检测.该方法检测快速,线性范围为6.0×10~(-5)～66.0×10~(-5)mol/L(r=0.999 7,n=11),检出限(S/N=3)为1.8×10~(-5) mol/L.方法成功用于临床血清样品中葡萄糖含量的检测.