Oriented Nickel Nanonetworks and Their Submicron Fibres as a Basis for a Transparent Electrically Conductive Coating

The paper demonstrates a technique for applying an oriented nickel network to a glass surface. The method is based on the chemical reduction of nickel salt. The shaping and orientation of the resulting system are carried out using a micellar template of a surfactant and a magnetic field. Submicron nickel fibres are used to impart unity to the plurality of individual-oriented nickel nanonetworks. The result is a single conductive coating on the surface of the glass, which has a transparency in the optical range. Investigations of the structure, chemical composition, morphology and electrical conductivity of the coating were performed.     

Titanium Anodes with Active Coatings Based on Iridium Oxides: A Sublayer between the Active Coating and Titanium

An optimum composition and a technique for applying a protecting sublayer on titanium are substantiated experimentally. The sublayer prevents the oxidation of titanium during the production and application of highly porous metal oxide anodes. The formation of such a sublayer involves several stages: (a) coating chemically polished and etched in 5-% hydrofluoric acid titanium with hexachloroiridic acid, (b) drying hexachloroiridic acid, (c) a two-step treatment of anodes in argon with a low concentration of oxygen at 350°C, and (d) a brief annealing of the anodes in air at 400°C. The application of such a sublayer makes sense especially in the case of an anode with a thin highly porous active coating. The remarkable protecting properties of the sublayer are due to the formation of a dense coating on titanium. The coating consists of metallic iridium, titanium, and an amount of oxides of these metals. The titanium substrate itself undergoes minimum oxidation.     

ZSM-5／Silicalite-1核壳分子筛含氟水热体系的合成及表征

以圆柱形ZSM-5为核,用柠檬酸对其外表面进行预处理后,在含氟壳层晶化体系中二次生长合成核壳分子筛.通过X射线衍射、扫描电镜、透射电镜、N2吸附及氨程序升温脱附对分子筛进行了表征,并以甲苯歧化和1,3,5-三甲苯裂化为探针反应对分子筛性能进行了考察.结果显示,产物是以ZSM-5为核、silicalite-1纳米晶为壳的两相复合微孔分子筛材料;在含氟体系中ZSM-5外延生长出了致密壳层;全硅壳层的覆盖度约达到97%,核壳分子筛的外表面酸位随之减少,但基本保持孔道内的酸性。     

A lubricated stagnation point flow of nanofluid with heat and mass transfer phenomenon: Significance to hydraulic systems

The improved thermal association of heat transfer is considerably observed due to interaction of nanoparticles in recent days. The lubrication phenomenon with heat and mass transfer effects plays a key role in the hydraulic systems. In current research, the thermal impact of nanofluid over a lubricated stretching surfaces near a stagnation point analytical has been studied. A thin layer of lubricating fluid with a variable thickness provides lubrication. The inspection of thermophoresis and Brownian motion phenomenon is illustrated via Boungrino model. The analytical finding of refurbished boundary layer ordinary differential equations is obtained by a reliable and proficient technique namely variational iteration method (VIM). The Lagrange Multiplier is a potent tool in proposed technique to reduce the computational work. In addition, a numerical comparison is presented to show the effectiveness of this study. The range of flow parameters is based on theoretical flow assumptions. Physical inspection of involved parameters on velocities, temperatures, concentrations, and other quantities of interest when lubrication is presented. The current results present applications in polymer process, manufacturing systems, heat transfer and hydraulic systems.     

Zur Reaktion von Dihydroxybiphenylen mit Phosphorpentachlorid ‐ Phosphepine mit Phosphonium‐ und Phosphoranstruktur

The 2, 2'‐dihydroxybiphenyl derivatives 1d‐f react with phosphorus pentachloride to give the dioxaphosphepinium hexachlorophosphates 3a, 3b , and 17 . The trichloro‐dioxaphosphepins 8a, 8b , and 21 were discussed as intermediates, which were obtained by chlorination of the 6‐chloro‐dioxaphosphepins 7a, 7b , and 20 . The hydrolysis of the dioxaphosphepins leads to the stable, cyclic phosphates 4a, 4b, 9a, 9b, 11a, 11b, 19a, and 19b . The crystal struc‐ture of 4a was determined; two different molecules was observed in the asymmetric unit.     

功能性CdSe纳米晶的合成及自组装膜光致发光

以巯基丙酸(RSH)为稳定剂,采用湿化学法合成了功能性CdSe纳米晶,用XRD、TEM表征其粒度和形貌,用UV-Vis监测成核及成膜过程。结果表明：制得的CdSe近似呈球形,平均粒径为48 nm。利用静电自组装法层层组装成CdSe-PDDA复合膜,荧光测试表明：所得CdSe纳米晶自组装复合膜(CdSe-PDDA)的荧光强度随着组装层数的增加而呈线性增强,该复合膜在582 nm附近有黄绿色荧光发射。     

Characterisation of optical detectors using high-accuracy instruments

The facilities of the Metrology Research Institute at the Helsinki University of Technology, and methods for characterisation of optical detectors for spectral radiant intensity and irradiance responsivity, are described. The instrumentation for such characterisations includes a reference spectrometer with a number of auxiliary set-ups, and equipment for the spectral irradiance measurements with a filter radiometer based on a trap detector. The methods of realising the spectral responsivity scales based on an absolute cryogenic radiometer in house are addressed. The procedures and results of characterisation of a multipoint measuring system of photosynthetically active radiation, by employing the available facilities, are briefly described. The absolute irradiance responsivity of the device is determined by using a photometric lamp, whose spectral irradiance has been measured with the filter radiometer. The combined standard uncertainty of this set of calibrations is 3.6% at the 1σ level. The uncertainty is caused almost completely by the multipoint measuring system.     

Thermoresponsive hydrogel of poly(glycidyl methacrylate‐co‐N‐isopropylacrylamide) as a nanoreactor of gold nanoparticles

The synthesis of a thermoresponsive hydrogel of poly(glycidyl methacrylate‐co‐N‐isopropylacrylamide) (PGMA‐co‐PNIPAM) and its application as a nanoreactor of gold nanoparticles are studied. The thermoresponsive copolymer of PGMA‐co‐PNIPAM is first synthesized by the copolymerization of glycidyl methacrylate and N‐isopropylacrylamide using 2,2′‐azobis(isobutyronitrile) as an initiator in tetrahydrofuran at 70 °C and then crosslinked with diethylenetriamine to form a thermoresponsive hydrogel. The lower critical solution temperature (LCST) of the thermoresponsive hydrogel is about 50 °C. The hydrogel exists as 280‐nm spheres below the LCST. The diameter of the spherical hydrogel gradually decreases to a minimum constant of 113 nm when the temperature increases to 75 °C. The hydrogel can act as a nanoreactor of gold nanoparticles because of the coordination of nitrogen atoms of the crosslinker with gold ions, on which a hydrogel/gold nanocomposite is synthesized. The LCST of the resultant hydrogel/gold nanocomposite is similar to that of the hydrogel. The size of the resultant gold nanoparticles is about 15 nm. The hydrogel/gold nanocomposite can act as a smart and recyclable catalyst. At a temperature below the LCST, the thermoresponsive nanocomposite is a homogeneous and efficient catalyst, whereas at a temperature above the LCST, it becomes a heterogeneous one, and its catalytic activity greatly decreases. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2812–2819, 2007     

生物质三组分热裂解行为的对比研究

在热天平上对比研究了生物质中的纤维素、半纤维素和木质素三种主要组分的热失重规律。结果表明，作为半纤维素模型化合物的木聚糖热稳定性差，在217℃～390℃发生明显分解；纤维素热裂解起始温度最高，且主要失重发生在较窄温度区域，固体残留物仅为6.5%；木质素表现出较宽的失重温度区域，最终固体残留物高达42%。在红外辐射机理试验台上对比研究了三组分热裂解产物随温度的变化规律。三组分热裂解生物油产量随温度变化先升后降。纤维素生物油产量在峰值上最高，但纤维素生物油热稳定性差，高温时挥发分的二次分解最明显；木聚糖和木质素生物油产量较低，表现出较好的热稳定性。三组分热裂解焦炭产量随温度升高而降低，最终纤维素热裂解焦炭产量为1.5%，而木聚糖和木质素分别为22%和26%。三组分热裂解气体产物随温度升高而增长，但在气体组成分布上因三组分的结构上的差异而不同。     

Development of Enzyme Conductometric Biosensor for Dopamine Determination in Aqueous Samples

Dopamine is a biologically active chemical that performs a number of vital functions as a hormone and neurotransmitter. Therefore, the determination of dopamine concentration in the human body is important for biomedical research. The content of dopamine in the blood varies depending on the age of a healthy person and can serve as a prognostic marker of many diseases. The aim of this work was to develop a new enzyme conductometric biosensor for the determination of dopamine in aqueous samples and to study the biosensor's analytical characteristics. The conductometric method of analysis with differential measurement mode was used in the work. Two pairs of gold interdigitated electrodes deposited on a sitall substrate were used as a conductometric transducer. The biorecognition element of the biosensor was based on laccase immobilized by glutaraldehyde cross-linking. The optimal conditions of laccase immobilization were selected. The influence of solution parameters (ionic strength, pH, buffer capacity) on the biosensor work was investigated. The biosensors demonstrated high sensitivity to dopamine (minimum limit of detection −7.8 μM) with the linear range up to 1 mM. The biosensor was highly selective and reusable. The proposed biosensor was tested regarding the possibility of its long-term storage under different conditions. The developed conductometric biosensor was proven to be suitable for measuring dopamine concentration in biological and pharmaceutical samples.     

低压下酞菁裂解法制备定向碳纳米管阵列

在低压条件下以酞菁铁为原料, 采用独立双温控加热系统在石英玻璃基底上气相沉积制备了大面积准直性好和管径均匀的碳纳米管. 利用扫描电子显微镜(SEM/FESEM)和透射电子显微镜(TEM)研究了定向碳纳米管的生长形态和结构. 详细讨论了系统真空度、反应温度、气体流速及氢气和氩气的体积比例等参数对碳纳米管生长的影响, 并测试了该碳纳米管的场发射性能及超电容性能.     

Sequential injection with lab-at-valve (LAV) approach for potentiometric determination of chloride

Sequential injection with “Lab-at-Valve (LAV)” approach is demonstrated for potentiometric determination of chloride. The LAV flow-through electrode system consists of two Ag/AgCl electrodes: one as a reference electrode, silver chloride activated surface-silver wire soaked in a constant-concentration chloride ion solution in a small tube covered with a polymer-membrane, another as a working electrode (a similar silver chloride activated surface-silver wire) placed in a flow channel. The electrode system is attached at one port of a 10 port multiposition valve. A modified autoburette was used as a propelling device. Using SI operation via a program written in-house, based on LabVIEW^®, a standard/sample is inserted, via the selection valve, in potassium nitrate as an electrolyte and water is used as a carrier. The zones are transported from the holding coil to the flow cell to monitor the difference in potential due to concentration cell behavior. The potential difference is then recorded as a peak. Peak height is proportional to logarithm of chloride concentration. The SI-LAV for chloride determination is very simple, fast, precise, accurate, automatic and economical. Applications to mineral drinking water and surface water have been made. The results agree with those of IC and titrimetric methods.     

Multioperational Oxidase Biosensors Based on Carbosilane Dendrimers with Interacting Ferrocenes

The bioelectrocatalytical properties and kinetic characteristics of new oxidase biosensors based on two different carbosilane dendrimers are described. The best glucose biosensor developed displayed, in an ascorbate interference free work potential interval, a strictly linear range from 0 to 4.0 mM, a detection limit of 40,6 μM and a response time less than 3 s. The lactate biosensor displayed a linear range from 0 to 0.8 mM, a detection limit of 0.73 µM and a response time less than 2 s. The apparent Michaelis–Menten constants were calculated to be 4.39 mM and 2.08 mM respectively, according to Lineweaver–Burk equation.     

Fabrication of a Simple and Cheap Screen-printed Silver/Silver Chloride (Ag/AgCl) Quasi-reference Electrode

In this work, a silver/silver chloride ink is fabricated using two steps. First the silver ink is prepare using silver, nail polish and acetone. Then the silver ink is painted in a paper substrate and a silver chloride layer is deposited using a bleach solution. The result is the silver/silver chloride conductive ink. The silver ink is cheap ($2.49/g), well-dispersive and very easy to fabricate. The materials were characterized by SEM and XRD. The Ag ink showed the formation of a continuous network throughout the silver ink film with fewer agglomeration. The effective chlorination process was also observed in the Ag/AgCl characterization. Since the Ag/AgCl substrate will be used as a quasi-reference electrode, it is important to investigate the electrical properties. The Ag ink showed an average ohmic resistance of 2.27 Ω. The addition of the AgCl layer decreases the conductivity, as expected. In summary, the Ag/Ag/Cl ink developed is simple, well-dispersed, cheap and with good conductivity. Therefore, it can be used as a conductive ink in the fabrication of quasi-reference electrodes.     

Photocurable Sol-Gel Coatings: Channel Waveguides for Use at 1.55 μm

The development and characterization of channel waveguides using wet-process, low temperature sol-gel chemistry is described. Two structures have been developed. The first one is a one-layer structure, composed of a sol-gel solution which is a mixture of photopolymerizable organosilicate and organozirconate precursors. The other is a multilayer structure with a buffer under the guide and a protective coating. The layers are deposited by the dipping technique. The devices are obtained by UV light exposure of the coating through a predefined mask (channel waveguides). The refractive index increase is sufficient enough to allow the use of waveguides in the 1.55 m telecommunication window.These waveguides are thick enough to reduce the coupling losses with an optical fiber below 0.5 dB. Also, because of our sandwich structure, the propagation losses are less than 0.1 dB.     

Analysis of nucleosides and monophosphate nucleotides from mushrooms with reversed‐phase HPLC

The retention characteristics of five stationary phases were tested by using a selection of 5′‐mononucleotides and nucleosides with the aim to develop a simple, rapid and sensitive reversed‐phase liquid chromatography method without ion‐pair reagent usage. The method was optimized by changes in temperature, pH and ionic strength on a column showing a superior performance. The mobile phase consisted of a mixture of 0.05 M phosphate buffer and methanol, delivered at a flow rate of 0.4 mL/min and based on a gradient program. UV detection was used at a 254 nm wavelength. The method was validated for a quantitative analysis of 5′‐mononucleotides and nucleosides in wild edible mushrooms. For all nucleosides and nucleotides, the LOD and LOQ were less than 0.02 and 0.07 μg/mL, respectively. Validation parameters yielded recovery rates between 68.6 and 98.2%, with a precision expressed as a relative standard deviation of 7.6–15.3%. The content of 5′‐mononucleotides and nucleosides was determined for 10 samples of wild edible mushrooms found in Croatia and, accordingly, the equivalent umami concentrations were calculated.     

A nanoscale vesicular polydiacetylene sensor for organic amines by fluorescence recovery

We report a nanoscale lipid membrane-based sensor of conjugated polydiacetylene (PDA) vesicles for fluorescence detection of organic amines. The vesicle sensor was constructed by incorporation of a BODIPY fluorescent dye into the PDA vesicles. The fluorescent properties of the resulting vesicles can be manipulated by adjusting lipid components, and are controlled by environmental and solution conditions. The fluorescence of the BODIPY dye was significantly quenched in the polymerization of diacetylene lipid vesicles by a UV irradiation process. However, it was sufficiently recovered by external stimuli such as a hike of solution pH. The fluorescence recovery process was reversible, and a decrease in solution pH resulted in repeated quenching. The reported system transforms an external stimulus into a large fluorescence intensity change, demonstrating great potential in developing new signal reporting method for biosensor design. The quench-recovery phenomenon of the BODIPY-PDA is believed to be related to the energy transfer between the dye and the PDA conjugate backbone. The vesicle sensor was applied for detecting an organic amine, triethylamine (TEA) and a large linear relationship was obtained between the increase in fluorescence intensity and the concentrations of TEA. The detection limit of TEA by vesicle sensors using fluorescence recovery was found to be 10 μM.     

Thermotropic rigid chain copolymers I. crystallization kinetics and thermodynamic properties

The kinetics of structure formation and the thermal properties of the ordered phase were analyzed calorimetrically for a rigid polymer, characterized by an irregular chemical structure. The transition from the nematic melt to a partially ordered state was found to involve two different processes, a fast and a slow one. The fast one corresponds apparently to a thermally activated nucleation and growth mechanism, whereas the slow one is strongly self delaying. Its transition rate is only weakly dependent on the temperature. The thermal properties of the ordered phase, resulting from this process, vary strongly with the annealing temperature and annealing time. The enthalpy and entropy of fusion, characteristic for the pure ordered phase, are lower by a factor of about 10 in comparison to the corresponding values of flexible chain molecules.     

聚苯胺在电化学电容器中的应用

The performance of a newly designed, polyaniline activated carbon, hybrid electrochemical capacitor was evaluated. The polyaniline was prepared by the chemical oxidation/polymerization process. The capacitor was assembled by using polyaniline as a positive electrode and an activated carbon as a negative electrode respectively. From a cyclic voltammograms test, a specific capacitance of 420 F/g was obtained for polyaniline electrode. The cycle life of the cell is proved to be more than 1000 times by the Galvanostatic charge and discharge test. Values for the specific energy and real specific power of 15.5 Wh/kg and 2.8 W/g, respectively, are demonstrated for a cell voltage between 0.0 and 1.4 V. The max specific power for the hybrid capacitor amounts to 20.4 W/g.     

Rheological evidence for the existence of subphases in the liquid crystalline 4-n-alkoxybenzoic acids

The rheological behaviour of the homologous series, the alkyloxybenzoic acids, has been studied at steady flow and small amplitude oscillatory shear. The temperature dependencies of the viscosity were compared with differential scanning calorimetry data in order to estimate pretransitional phenomena in mesophases. The values of the viscosity and flow activation energy (E) can be indicative of the mesophase state. 4-n-pentyloxybenzoic acid yields a classic nematic (N) phase while the next homologues show a cybotactic nematic phase having a higher E value. The N phase is a Newtonian fluid of lower viscosity than that of the isotropic phase. The cybotactic nematic phase by its rheological properties takes an intermediate position between the N phase and a smectic C (SmC) phase. The SmC phase is a viscoelastic and viscoplastic medium. The SmC phase of 4-n-octyloxy-, 4-n-nonyloxy-, 4-n-decyloxy- and 4-n-dodecyloxybenzoic acid can exist in high- and low-ordered states. The more ordered smectic phase is characterised by higher stiffness, viscosity and yield stress than those of the less ordered. The SmC phase of 4-n-hexadecyloxybenzoic acid is characterised by the only state with unstable value of apparent viscosity. The phase state and the transition temperature can be dependent on the thermal history of the sample and a mechanical shear.