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Glass Electrode (glass + electrode)
Selected AbstractsInfluence of drinking method on tooth-surface pH in relation to dental erosionEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2004Ann-Katrin Johansson The aim of this investigation was to study the intraoral pH response on tooth surfaces in relation to dental erosion during and after drinking a sugar-free cola-type soft drink. Six different methods of drinking were tested in a randomized order: holding; short-sipping; long-sipping; gulping; nipping; and sucking. Two methods of pH measurement were used in two series of individuals. In the first series, pH was measured by using the microtouch method in 12 healthy adults at three dental erosion-prone sites: 11 palatally; 11 buccally; and at the mesiobuccal cusp tip of 16. In the second series, pH was measured by using the telemetric method in 6 healthy individuals, producing continuous recordings of pH by means of a glass electrode in a specified approximal area. The two series showed similar results, although the telemetric method generally recorded larger pH falls. Holding the drink in the mouth before swallowing led to the most pronounced pH drop, followed by the long-sipping method. Gulping resulted in only a small decrease of pH. No differences among the three intraoral sites were found when analyzed by using the microtouch method. The conclusion from this study is that the drinking method strongly affects tooth-surface pH and thereby the risk for dental erosion. It therefore seems appropriate to include advice on the method of drinking in dietary counseling related to dental erosion. [source] Investigation of the electropolymerization of o -toluidine and p -phenylenediamine and their electrocopolymerization by in situ ultraviolet,visible spectroelectrochemistryJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Guirong Zhang Abstract Under the conditions of potentiostatic electrolysis, the electropolymerization of o -toluidine (OT) and para -phenylenediamine (PPDA) and the electrocopolymerization between OT and PPDA on an indium tin oxide (ITO) conductive glass electrode at potentials of 0.7, 0.8, and 0.9 V were studied in detail by in situ ultraviolet,visible (UV,vis) spectrometry in 0.5 mol/L sulfuric acid media. It was shown that both OT and PPDA could be electropolymerized on the ITO electrode, which depended on the applied electrolysis potential and the concentration of the monomer. Furthermore, in situ UV,vis spectra indicated that the electrocopolymerization between OT and PPDA could happen. The presence of PPDA not only promoted polymerization but also accelerated polymerization, which was attributed to the formation of an intermediate result from the coupling of PPDA and the toluidine monomer cation radical. PPDA could be incorporated into the copolymer to make the copolymer have a phenazine or phenazine-like cyclic structure, which was proven by the reflectance Fourier transform infrared spectra of the polymer and copolymer. The scanning electron microscopy morphology images of the polymers obtained showed that, in addition to accelerating polymerization, PPDA also could change the method of nucleation for the polymer to make the copolymer possess a fibrous surface morphology. The diameter of the fibroid copolymer was about 100 nm, and the length of that reached about 1000 nm. In the article, a newer concerned mechanism of copolymerization was proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Development and application of an excitation ratiometric optical pH sensor for bioprocess monitoringBIOTECHNOLOGY PROGRESS, Issue 6 2008Ramachandram Badugu Abstract The development of a fluorescent excitation ratiometric pH sensor (AHQ-PEG) using a novel allylhydroxyquinolinium (AHQ) derivative copolymerized with polyethylene glycol dimethacrylate (PEG) is described. The AHQ-PEG sensor film is shown to be suitable for real-time, noninvasive, continuous, online pH monitoring of bioprocesses. Optical ratiometric measurements are generally more reliable, robust, inexpensive, and insensitive to experimental errors such as fluctuations in the source intensity and fluorophore photobleaching. The sensor AHQ-PEG in deionized water was shown to exhibit two excitation maxima at 375 and 425 nm with a single emission peak at 520 nm. Excitation spectra of AHQ-PEG show a decrease in emission at the 360 nm excitation and an increase at the 420 nm excitation with increasing pH. Accordingly, the ratio of emission at 420:360 nm excitation showed a maximum change between pH 5 and 8 with an apparent pKa of 6.40. The low pKa value is suitable for monitoring the fermentation of most industrially important microorganisms. Additionally, the AHQ-PEG sensor was shown to have minimal sensitivity to ionic strength and temperature. Because AHQ is covalently attached to PEG, the film shows no probe leaching and is sterilizable by steam and alcohol. It shows rapid (,2 min) and reversible response to pH over many cycles without any photobleaching. Subsequently, the AHQ-PEG sensor film was tested for its suitability in monitoring the pH of S. cereviseae (yeast) fermentation. The observed pH using AHQ-PEG film is in agreement with a conventional glass pH electrode. However, unlike the glass electrode, the present sensor is easily adaptable to noninvasive monitoring of sterilized, closed bioprocess environments without the awkward wire connections that electrodes require. In addition, the AHQ-PEG sensor is easily miniaturized to fit in microwell plates and microbioreactors for high-throughput cell culture applications. [source] Electrocatalysis and Amperometric Detection of the Reduced Form of Nicotinamide Adenine Dinucleotide at Toluidine Blue/Zinc Oxide Coated ElectrodesELECTROANALYSIS, Issue 18 2007Ashok Kumar Abstract Thin toluidine blue (TBO) and zinc oxide (ZnO) hybrid films have been grown on glassy carbon electrode (GCE) and indium tin oxide coated (SnO2) glass electrodes by using cyclic voltammetry (CV). Scanning electron microscopy (SEM) images revealed spherical and beads-like shape of highly oriented TBO/ZnO hybrid films. Energy dispersive spectrometry (EDS) results declared that the films composed mainly of Zn and O. Moreover, TBO/ZnO hybrid films modified electrode is electrochemically active, dye molecules were not easily leached out from the ZnO matrix and the hybrid films can be considered for potential applications as sensor for amperometric determination of reduced nicotinamide adenine dinucleotide (NADH) at 0.0,V. A linear correlation between electrocatalytic current and NADH concentration was found to be in the range between 25,,M and 100,,M in phosphate buffer. In addition, we observed that dopamine, ascorbic acid and uric acid are not interference in amperometric detection of NADH in this proposed method. In addition, TBO/ZnO hybrid film modified electrode was highly stable and its response to the NADH also remained relentless. [source] Template-Directed Liquid ALD Growth of TiO2 Nanotube Arrays: Properties and Potential in Photovoltaic DevicesADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Thelese R. B. Foong Abstract Dense and well-aligned arrays of TiO2 nanotubes extending from various substrates are successfully fabricated via a new liquid-phase atomic layer deposition (LALD) in nanoporous anodic alumina (AAO) templates followed by alumina dissolution. The facile and versatile process circumvents the need for vacuum conditions critical in traditional gas-phase ALD and yet confers ALD-like deposition rates of 1.6,2.2,Å cycle,1, rendering smooth conformal nanotube walls that surpass those achievable by sol,gel and Ti-anodizing techniques. The nanotube dimensions can be tuned, with most robust structures being 150,400,nm tall, 60,70,nm in diameter with 5,20,nm thick walls. The viability of TiO2 nanotube arrays deposited on indium tin oxide (ITO),glass electrodes for application in model hybrid poly(3-hexylthiophene) (P3HT):TiO2 solar cells is studied. The results achieved provide platforms and research directions for further advancements. [source] | ||||||||||