共查询到20条相似文献,搜索用时 15 毫秒
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Following protein kinase acivity by electrochemical means and contact angle measurements 总被引:1,自引:0,他引:1
Wieckowska A Li D Gill R Willner I 《Chemical communications (Cambridge, England)》2008,(20):2376-2378
The electrochemical analysis of the protein kinase, casein kinase, is accomplished by the voltammetric response of Ag(+) ions associated with the phosphorylated product; the sensing surface is regenerated by the cleavage of the phosphorylated product with alkaline phosphatase, and the phosphorylation/de-phosphorylation processes are monitored by XPS and contact angle measurements. 相似文献
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L. Alexandrova K. Hanumantha Rao K.S.E. Forsberg L. Grigorov R.J. Pugh 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,348(1-3):228-233
The stability and interactions in thin wetting films between the silica surface and air bubble containing (a) straight chain C10 amine and (b) cationic/anionic surfactant mixture of a straight chain C10 amine with sodium C8, C10 and (straight chain) C12 sulfonates, were studied using the microscopic thin wetting film method developed by Platikanov [D. Platikanov, J. Phys. Chem. 68 (1964) 3619]. Film lifetimes, three-phase contact (TPC) expansion rate, receding contact angles and surface tension were measured. The presence of the mixed cationic/anionic surfactants was found to lessen contact angles and suppresses the thin aqueous film rupture, thus inducing longer film lifetime, as compared to the pure amine system. In the case of mixed surfactants heterocoagulation could arise through the formation of positively charged interfacial complexes. Mixed solution of cationic and anionic surfactants shows synergistic lowering in surface tension. The formation of the interfacial complex at the air/solution interface was confirmed by surface tension data. It was also shown, that the chain length compatibility between the anionic and cationic surfactants system controls the strength of the interfacial complex. The observed phenomena were discussed in terms of the electrostatic heterocoagulation theory, where the interactions can be attractive or repulsive depending on the different surface activity and charge of the respective surfactants at the two interfaces. 相似文献
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Milivoj Lovrić Michael Hermes Fritz Scholz 《Journal of Solid State Electrochemistry》2000,4(7):394-401
Cyclic voltammograms of electroactive solid compounds with partial immiscibility between the oxidized and reduced phases
can exhibit a splitting of the peaks. If the free energy of transformation between the oxidized and reduced phases is small,
the formal potentials of the redox pair will be almost the same in both solid phases. This results in an inert potential range
in which no appreciable electrochemical activity is possible. The kinetic implications of this situation have been analysed
in relation to the width of the miscibility gap. The diffusion of ions in the particle, which is hindered by the immiscibility,
can proceed when a transition zone between the two phases exists in which the crystal structure is changed. If there is no
such transition zone the voltammogram will display several spikes, which are caused by the collapse of concentration barriers
at the sharp interfaces between the two phases in the mixed crystals.
Received: 14 October 1999 / Accepted: 4 November 1999 相似文献
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F. Scholz L. Nitschke G. Henrion F. Damaschun 《Fresenius' Journal of Analytical Chemistry》1989,335(2):189-194
Summary Abrasive stripping voltammetry possesses several features of a spectroscopy. It allows the qualitative and quantitative analysis of electroactive solid materials. This work is focussed on the application for the unambiguous identification of minerals (sulphides, sulfo-salt minerals, fahlores). g-amounts of a mineral are sufficient to perform a series of measurements. Three different voltammetric modes were used to study the electrochemical behaviour of the minerals.
Abrasive Stripping Voltammetry — eine elektrochemische Spektroskopie für Festkörper: Anwendung auf Mineralidentifizierungen相似文献
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《Solid State Sciences》2007,9(7):580-587
Single crystals of [(H2O)⊂(DB18C6)(μ2-H2O)2/2][(H3O)⊂(DB18C6)(μ2-H2O)2/2]I3 1 were shown to possess ideally stacked crown ether molecules which form channels running in one direction through the solid state structure. By immersion of single crystals of 1 into NaOH, ion exchange takes place to yield the compound [(Na)⊂(DB18C6)(μ2-H2O)2/2][(Na)⊂(DB18C6)(μ2-OH)2/2]I3 2, with slightly but significantly different cell parameters. Both compounds were tested for transport properties through these channels by using two different devices, one for water transport, the other for NaOH transport, through single crystals of 1 and 2, respectively. The results indicate that transport can take place via a hopping mechanism. 相似文献
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A cell is described which allows in situ incident-light microscopy to be used for the analysis of solid state electrochemical reactions studied by abrasive stripping voltammetry. The cell provides the possibility to screen solid compounds with respect to their electrochromic properties without requiring the preparation of special electrodes on transparent and conducting materials. Silver octacyanomolybdate(IV) and silver octacyanotungstate(IV) have been used to study the performance of the cell because both compounds exhibit a stable electrochromic and voltammetric behaviour. 相似文献
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Interpretation of contact angle measurements on two different fluoropolymers for the determination of solid surface tension 总被引:2,自引:0,他引:2
Tavana H Simon F Grundke K Kwok DY Hair ML Neumann AW 《Journal of colloid and interface science》2005,291(2):497-506
Contact angle measurements with a large number of liquids on the semi-fluorinated acryl polymer EGC-1700 films are reported. The surface tension was determined to be gammasv=13.84 mJ/m2 from contact angles of octamethylcyclotetrasiloxane (OMCTS) and decamethylcyclopentasiloxane (DMCPS). Inertness of these two liquids makes them ideal for determination of surface tension of low-energy fluoropolymers. On the other hand, contact angles of many other liquids deviated somewhat from a smooth contact angle pattern that represents the EGC-1700 surface tension. It is argued that noninertness of the molecules of these liquids gives rise to specific interactions with the polymer film, causing the deviations. Furthermore, contact angles of a series of n-alkanes (n-hexane to n-hexadecane) showed systematic deviations from this curve, similar to the trend observed for n-alkanes/Teflon AF 1600 systems studied earlier. Adsorption of vapor of short-chain liquids onto the polymer film caused their contact angles to fall above the gammasv=13.84 mJ/m2 curve, and a parallel alignment of molecules of the long-chain n-alkanes in the vicinity of the solid was the explanation for the deviation of their contact angles below it. It is found that vapor adsorption effect is more significant in the case of Teflon AF 1600, while the alignment of liquid molecules close to the surface is more pronounced for EGC-1700. 相似文献
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Guillaume Herlem Rabah Zeggari Sandrine Monney Yves Guillaume Tijani Gharbi 《Talanta》2010,82(1):417-421
The anodic oxidation of concentrated glycine based aqueous electrolyte on smooth platinum electrode leads to a strongly grafted polyglycine-like coating on the surface in an irreversible way. Due to the proton affinity towards amino groups of polyglycine (PG), the electrodeposited thin film was used as receptor for solid potentiometric pH sensor. In order to reach local pH measurement, we developed miniaturized microelectrodes on glass substrate thanks to photolithography process. We used silver chloride on silver as the reference electrode. The couple (silver chloride, PG based platinum electrode) of microelectrodes gives linear potentiometric response vs. pH in the range [2-12], reversibly and with a sensitivity of 52.4 mV/pH (for 1 mm electrode size). PG based pH electrode is compared to other organic polymer based pH receptor such as linear polyethylenimine (L-PEI), polyaniline (PANI) and glass membrane. 相似文献
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Abrasive stripping voltammetry is a new electroanalytical technique designed for the qualitative and quantitative analysis of solid materials. It is based upon a preliminary mechanical transfer of trace amounts of a solid sample onto the surface of an electrode. All conventional electrochemical measuring methods can be used. The technique is applicable in many fields of solid state analysis and for fundamental studies of the electrochemistry of solid compounds. 相似文献
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The influence of various factors such as solubility, the oxidation of the membrane, and the contamination of the solution, on the experimental values of the selectivity coefficients of solid state sulphide ion selective electrodes is discussed. A new method for the evaluation of very small selectivity coefficients, based on the addition of reagents forming complexes or insoluble salts with the main ion, is proposed. By means of this method, selectivity coefficients for silver, copper, cadmium and lead ion selective electrodes have been determined, which are in far better agreement with thermodynamic values than those described in the literature. 相似文献
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F. Bonino M. Lazzari A. Lonardi B. Rivolta B. Scrosati 《Journal of solid state chemistry》1977,20(3):315-321
The systems AgIAg2Mo2O7 and AgIAg2Mo4O13 have been investigated by differential scanning calorimetry, X-ray analysis, and conductivity to characterize intermediate compounds with fast ion transport in the solid state. The results indicate that in the first system there is a new phase, at about 75 mole% AgI, which initially contains a small amount of an Ag2MoO4, 4AgI phase in a metastable condition. In the AgIAg2Mo4O13 system no formation of highly conductive intermediate compounds was detected but rather a decomposition in Ag2Mo2O7, 75 m/o AgI, and MoO3 was observed. The results have been qualitatively discussed in terms of the role of the minority substituting polymolybdate anions leading to the formation of open-structured compounds of the AgI-modified type. 相似文献
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The electrical conductivity of the 40Na2O:50SiO2:10B2O3 glass-dispersed Na2CO3 composite solid electrolyte system, prepared by liquid phase sintering, is systematically investigated using complex impedance
spectroscopy. The unreacted glass glues the Na2CO3 grains together, which not only reduces the micropores but also improves the ionic conductivity and mechanical strength of
the pellet. The conductivity enhancement in such a composite solid electrolyte system is discussed in the light of the increased
concentration of charge carriers in a diffuse space charge layer formed at the crystalline-glass interface. A galvanic CO2 gas sensor using an optimised composite electrolyte (50 wt% glass-dispersed Na2CO3) is found to be more stable against thermal cycles (heating and cooling) vis-à-vis the sensor based on a pure crystalline
solid electrolyte.
Received: 12 June 1998 / Accepted: 21 October 1998 相似文献
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Transition Metal Chemistry - 相似文献
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Alicia S. Johnson Asmira Selimovic R. Scott Martin 《Analytical and bioanalytical chemistry》2013,405(10):3013-3020
The use of microchip devices to study cellular systems is a rapidly growing research area. There are numerous advantages of using on-chip integrated electrodes to monitor various cellular processes. The purpose of this review is to give examples of advancements in microchip-based cellular analysis, specifically where electrochemistry is used for the detection scheme. These examples include on-chip detection of single-cell quantal exocytosis, electrochemical analysis of intracellular contents, the ability to integrate cell culture/immobilization with electrochemistry, and the use of integrated electrodes to ensure cell confluency in longer-term cell culture experiments. A perspective on future trends in this area is also given. 相似文献