不同波长的光对生物柴油氧化安定性的影响

为了研究光对生物柴油氧化安定性的影响,以小桐子生物柴油为研究对象,在20 ℃下用不同波长的光照射处理48 h,并对处理后的样品进行氧化安定性分析。 结果表明,不同波长的光对生物柴油氧化的促进作用是不同的,以紫光为代表的短波长光对小桐子油生物柴油氧化的促进作用最强,其诱导期由5.12 h降至2.65 h,减少48%;波长较长的红光对生物柴油氧化的促进作用最弱,其诱导期降至4.61 h,减少10%。 对不同波长的光处理的生物柴油进行酸值滴定、成分分析和紫外表征,结果表明,随着光波长的减小,生物柴油的酸值从0.2577 mg/g 增加到0.3438 mg/g;含有两个碳碳双键的亚油酸甲酯的相对含量降低;共轭双键的吸收峰增大。 说明光波长越短,对生物柴油氧化的促进作用越强。     

氧化苏木精复合电极测定牛奶中残留青霉素

氧化苏木精复合电极测定牛奶中残留青霉素;电流型电化学生物传感器;氧化苏木精;青霉素     

生物氧化还原研究中的薄层电化学技术

标准氧化还原电位 E~(0′)和电子转移化学计量数 n 的测定是生物氧化还原体系研究中的一个重要方面.由于许多生物分子会在电极上吸附,有些蛋白分子的氧化还原中心位于蛋白结构的内部,它们同电极的异相电子转移过程很不可逆或非常缓慢,因而难于用常规的电化学方法进行 E_(0′)和 n 值的测量。近年来薄层电化学技术的发展为这方面的研究打开了方便之门,本文简要介绍其原理及应用。     

甘油的催化选择氧化

综述了近年来生物柴油主要副产物甘油的催化选择氧化的研究进展。分析了甘油的化学催化选择氧化的反应网络;介绍了催化甘油选择氧化反应主要的催化剂如负载型金属催化剂、多孔催化剂以及有机酰基-TEMPO催化剂的催化性能及其催化机理;评述了甘油催化氧化过程中各反应条件等对产物选择性和反应物转化率的影响;概括了甘油的电催化氧化、甘油催化氧化聚合生成新型聚合物-聚丙酮二酸盐（Polyketomalonate）等新催化反应及其机理,总结了甘油生物催化氧化的产物二羟基丙酮（DHA）的新进展。最后提出了甘油的催化氧化存在的一些问题,并展望了甘油催化氧化的研究和发展方向。     

氧化石墨烯的表面化学修饰及纳米-生物界面作用机理

由于具备独特的物理化学性质,氧化石墨烯已被广泛地应用于生命科学与人体健康等相关领域.然而,如何最大化地发挥氧化石墨烯的优势与特点,并克服其自身固有性质导致的生物不良效应,依然是当前面临的难题.为更好地了解该领域的研究现状,本文主要综述了近年来氧化石墨烯的表面化学调控和生物作用机理方面的最新研究进展.首先,简要介绍了氧化石墨烯的物理化学特性、典型的表面化学调控策略（氧化还原、羧基化、氨基化、有机小分子修饰、聚合物修饰、多肽/蛋白修饰、核酸修饰和纳米颗粒修饰）,以及不同表面修饰引起的生物效应.继而,重点总结了氧化石墨烯表面修饰影响其生物效应的主要界面作用机理,包括蛋白冠形成、细胞膜损伤、膜受体作用与氧化应激损伤.最后,针对氧化石墨烯表面化学调控和生物效应与机理相关研究所面临的科学问题与挑战进行了展望.     

基于氧化铒-石墨烯氧化物复合纳米材料的葡萄糖氧化酶直接电化学性能及对葡萄糖的检测

将稀土纳米材料Er₂O₃用于构建葡萄糖生物传感器。Er₂O₃和氧化石墨烯形成复合基底,将葡萄糖氧化酶（GOD）固载在玻碳电极表面。首先利用SEM和XRD技术对所制备的Er₂O₃和氧化石墨烯纳米材料进行表征。利用EIS和CV对整个生物传感器制备过程进行表征。Er₂O₃的存在能有效的保持GOD的生物活性并加速其电子传递速率。由于Er₂O₃和氧化石墨烯之间的协同效应,使得制备的传感器具有一对良好的氧化还原峰,证实GOD和电极之间的直接传递性能。当用于对葡萄糖的电催化氧化时,传感器的CV响应随着葡萄糖浓度的增加而变弱。在葡萄糖浓度为1~10 mmol·L^-1范围内,CV响应值与葡萄糖浓度成线性关系。此外,传感器具有好的稳定性和重现性。     

基于氧化铒石墨烯氧化物复合纳米材料的葡萄糖氧化酶直接电化学性能及对葡萄糖的检测

将稀土纳米材料Er₂O₃用于构建葡萄糖生物传感器。Er₂O₃和氧化石墨烯形成复合基底,将葡萄糖氧化酶（GOD）固载在玻碳电极表面。首先利用SEM和XRD技术对所制备的Er₂O₃和氧化石墨烯纳米材料进行表征。利用EIS和CV对整个生物传感器制备过程进行表征。Er₂O₃的存在能有效地保持GOD的生物活性并加速其与电极之间的电子传递。由于Er₂O₃和氧化石墨烯之间的协同效应,使得制备的传感器在CV图中呈现一对明显的氧化还原峰,证实GOD和电极之间的直接电子传递性能。当用于对葡萄糖的电催化氧化时,传感器的CV响应随着葡萄糖浓度的增加而变弱。在葡萄糖浓度为1~10 mmol·L^-1范围内,CV响应值与葡萄糖浓度成线性关系。此外,传感器具有好的稳定性和重现性。     

厌氧氨氧化的生态因子研究进展

厌氧氨氧化生物脱氮技术是近年来发展起来的新型的生物脱氮技术,其实质是氨的亚硝化与亚硝化产物以氨为电子供体的还原相偶联.从生态因子的角度出发,综述了厌氧氨氧化的影响因子(生物因子及非生物因子)的研究进展.并对厌氧氨氧化的应用前景进行了展望,提出了其今后的研究方向.     

石墨烯在生物传感器中的应用

概述了石墨烯、石墨烯氧化衍生物的性质及制备方法,重点介绍了石墨烯在生物传感器中的应用以及发展趋势(引用文献49篇)。     

生物油部分氧化气化制备合成气研究

以生物油为原料,在常压和空气氛围下进行非催化部分氧化气化实验制备合成气,考察了气化温度、氧油比对合成气形成特性及合成气品质的影响,并对生物油非催化部分氧化气化制备合成气的主要反应过程进行了讨论。结果表明,升高温度可以促进生物油经非催化部分氧化气化制合成气过程中相关转化反应的进行,合适的氧油比有利于合成气的增加。当温度为1 050℃,空气量为0.2 L/min,进料量为72 g/h时,生物油经部分氧化产生的气体中H₂含量最高,CH₄、CO和CO₂很少;H₂/CO和H₂/(CO+CO₂)均达到最大值,分别为4.3和3.2。     

β-乳球蛋白在磁化水中的水合作用:磁化处理对水分子缔合构造及蛋白质水合特性的影响(英文)

为探讨蛋白质在磁化水中的水合作用,首先利用粘度测定及氧17核磁共振(17O-NMR)对经静磁场(MF)处理不同有效时间(teff)后的纯水进行了分析,进一步又利用差示扫描热量计(DSC)及NMR对溶解于磁化水的β-乳球蛋白(β-Lg)的水合特性进行了分析.随teff的增加,水分子的内能不断减小,处于氢键结合状态的水分子的比例不断增加.结果表明MF处理促进了水分子缔合结构的形成,这一点可能与氢键的形成有关.随teff的增加,β-Lg表面水分子的运动性没有明显变化,但β-Lg溶液中非自由结合水的含量不断增加.说明β-Lg的水合作用与水分子的缔合分布有关,该分布依存于水分子的氢键状态并可通过磁场处理加以改变.     

磁处理对水的导电性能影响的研究

分析了目前研究磁化水性能所用方法的缺陷，用正交试验的方法研究了不同磁感应强度和不同流速的磁化水的电阻率变化，考虑了各因素之间的交互作用，找出了最佳水平搭配；同时研究了磁化水的电阻率随时间的变化，发现磁化水的电阻率的变化具有滞后效应。     

Fischer–Tropsch synthesis over CNT-supported cobalt catalyst: effect of magnetic field

In the present work, the cobalt catalysts supported on carbon nanotubes (CNTs) were prepared by impregnation method in the presence and absence of magnetic field. The prepared catalysts were employed to yield higher hydrocarbons via Fischer–Tropsch synthesis. It is explored that using magnetized water can effectively change the catalyst geometry in impregnation catalyst preparation method. For the preparation of different sizes of cobalt particles on the CNTs support, the physical properties of solvent (water) in impregnation process were changed using the magnetizing process. The results showed that the average particle sizes of impregnated cobalt nanoparticles were decreased by using magnetized water in impregnation step. In addition, in the magnetized treated cobalt catalyst, the cobalt particles mostly dispersed outside the tubes because the capillary forces decreased by reducing water surface tension. Furthermore, the experimental results showed that the probability of chain growth (α) and selectivity to heavier hydrocarbons increased in magnetized water treatment catalysts.     

Evolution of the composition and structure of PAN carbon fiber during preoxidation

Using scanning electronic microscope, X-ray diffraction analysis, PYR-GCMS and IR etc., we studied the evolving process of the composition and structure of PAN carbon fiber during preoxidation. In the initial stage of preoxidation, PAN filament tows disappear and become semi-thaw. At first, reactions happen between the copolymers and esters disappear. The molecules annularly crosslink and the index of cyclation slowly increases. It is easy to fix the structure and form defects during the initial and the medium stages, which are most reactive. More traction is advised in these stages to minimize the structural deficiencies. In the medium stage of preoxidation, the fiber was reshaped into new sheet stacks and gradually changed to sheet sectors, and this structure tends to be stable in the final stage. Induced by acid and ester copolymer, PAN fiber forms a very stable cycle structure in the final stage. Besides, monomer, dimmer and trimer obviously decrease. In the final stage of the preoxidation, there exi     

A catalyst-free and green method for synthesis of 9-substituted-9H-diuracilopyrans in magnetized water: experimental aspects and molecular dynamics simulation

Research on Chemical Intermediates - The reactions of aldehydes and barbituric acid at low temperatures in magnetized water, as a green-promoting medium, provides 9-substituted-9H-diuracilopyrans...     

高锰酸钾引发魔芋粉/丙烯酰胺接枝共聚合及其增稠性研究

用KMnO4作引发刺对魔芋粉(KGM)与丙烯酰胺(AM)进行了接枝共聚反应．研究了引发剂浓度、接枝单体浓度、体系酸度、反应温度、反应时间以及KGM预氧化时间等条件对接枝效率的影响．结果表明：在适宜的条件下，接枝效率可达90％以上，并且接枝物的水溶性与增稠性得到较大的改善。     

Effect of magnetic field on enthalpy of solution of KCl in water

The enthalpies of solution of potassium chloride (KCl) in water and magnetically treated water (magnetized water) have been measured at 298.15 K using a LKB-8700 precision solution calorimeter. From the experimental results, it was observed that the effect of magnetic field on the enthalpy of solution is measurable. This is probably due to the distortion of the hydrogen bond of water resulting from magnetic treatment.     

低场核磁共振技术分析不同来源水分在烟丝中的分布状态及含水率的研究

采用低场核磁共振分析技术(LF-NMR)对不同来源水处理后的烟丝进行分析,研究了不同处理工艺样品的含水率及水分分布状态的变化。结果表明:水的种类对烘丝关键工序烟丝水分含量及分布状态具有明显影响。其中反渗透水和磁化水处理的样品含水率高于自来水处理后的样品,分别高0.43%和0.72%。得到薄板适宜的加工温度为140~150℃,气流干燥适宜的加工温度为180~210℃。     

Corrosion product build-up on stainless steel and its influence on hydrazine decomposition.60Co deposition in loop tests using borated water at 300°C

The corrosion rate of stainless steel decreases with time of operation under conditions characteristic of the primary circuit of pressurized-water reactors. Due to this the concentration of corrosion products in solution rapidly increases during heating-up and decreases after reaching the operation product levels is up to about three orders of magnitude. By a preoxidation treatment using potassium dichromate, the corrosion product release can be essentially diminished. In order to describe the influence of corrosion products in solution we investigate the thermal decomposition of hydrazine as well as the deposition behavior of⁶⁰Co. the half life of the thermal N₂H₄ decomposition at 300°C in borated water increases from about 1 to about 60 minutes, starting with glossy loop surfaces. Without adding boric acid to the water, half lives between 1 and 120 minutes were found; with an activation energy for the decomposition being estimated in the temperature region 270–310°C. The deposition behavior of⁶⁰Co is characterized by a very fast primary step, followed by retarded secondary deposition steps. The primary deposition step can be described by half lives of about 5 seconds. The influence of preoxidation treatment and subsequent decrease of corrosion product concentration on decomposition of N₂H₄ and deposition of⁶⁰Co is discussed.Presented at the Second International Symposium on Chemistry in High Temperature Water, Provo, UT, August 1991.Deceased (April 23, 1991).     

Preoxidation of CO on Os-modified Pt(111): a comparison with Ru-modified Pt(111)

The variation in CO adsorption structures during the preoxidation of CO on Os-modified Pt(111) (Pt(111)/Os) was investigated using cyclic voltammetry and electrochemical scanning tunneling microscopy. The spontaneous deposition of Os on Pt(111) resulted in randomly scattered islands with a coverage range of 0.13-0.54. During preoxidation on Pt(111)/Os, a phase transition from (2 × 2)-α to (√19 × √19) via the transient structures of (2 × 2)-β and (1 × 1) took place as on unmodified Pt(111). As the amount of Os increased, however, the transient structures of (2 × 2)-β and (1 × 1) appeared at lower potentials with higher populations. When the population of the transient structures was greater than 50%, an oxidative CO stripping process took place to the structure of (√19 × √19), completing the preoxidation. These observations strongly support the idea that the presence of Os increases the mobility of adsorbed CO by electronic modification of the Pt(111) surface (electronic effect). In addition, the results obtained with Pt(111)/Os were compared with those of Pt(111)/Ru.