Coatings, quartz

Changes in thermal stability and mass due to the formation of CdS nanoparticles in LB films were examined [180]. The LB films were formed onto gold-coated quartz oscillators from monolayers of arachidic acid or nonacosa-10,12-diynoic acid on CdCH containing subphases. The films were exposed to H2S gas until the mass change indicated complete conversion of Cd to CdS. The thermal stability of the H2S-treated films was reduced, with significant mass loss initiating at 55°C, compared to minimal mass loss in the untreated films up to at least 80°C under mild vacuum. The average CdS-particle size... 

The microarray consists of small DNA fragments, chemically synthesized at specific locations on a coated quartz surface. The number of locations on one array is in the range of millions. DNA is extracted and labeled from experimental samples, and then samples are hybridized on the array. Labels are monitored so that gene- and exon-level expression analysis, novel transcript discovery, genotyping, and resequencing can be carried out. 

SERS Substrates Based on Metal-Coated Quartz Posts... 

QCM measurements were carried out at air using AT-cut gold-coated quartz crystals with a resonant frequency of 9 MHz (5 mm-diameter, Seiko EG Q Seiko Instruments Inc). Prior to use, the quartz crystals were cleaned with water and ethanol. The frequency was measured before and after the monolayer transfer with the use of a Seiko EG G model 917 quartz crystal analyzer. 

Reproducible, If non-linear, analysis for most components employed capillary gas chromatography using, eg, OV-101 or DB-5 coated quartz columns (packed columns failed In our experiments). 

Here Fq and F are the frequencies of the non-coated or coated quartz in the (100) mode of the fundamental wave. Because of the ambiguity of the mathematical functions used, the Z value calculated in this way is not always a positively defined variable. This has no consequences of any significance because M is determined in another way by assessing Z and measuring the frequency shift. Therefore, the thickness and rate of the coating are calculated one after the other from the known M. 

Percival CJ, Stanley S, Galle TM, Braithwaite A, Newton MI, McHale G, Hayes W. Molecular-imprinted, polymer-coated quartz crystal microbalances for the detection of terpenes. Anal Chem 2001 73 4225-4228. 

Fig. 2 A Oscillator frequency changes with graft copolymerization of styrene (ST) on the dithiocarbamated copolymer-coated quartz crystal microbalance (QCM) in methano-lic solution with UV irradiation (light intensity 5mWcm ). Concentration of ST a 0, h 0.26, c 0.5, d 0.76 mol dm . B Relationship of oscillator frequency change calculated from A with concentration of ST...

Lindqvist subsequently described a similar system for the determination of HN03 (67). HN03 was collected on an Al2(S04)3-coated quartz denuder. The thermally desorbed NOx was determined by gas chromatogra-phy-photoionization detection. Subsequently Tanner et al. (68) simplified and fully automated the overall system configuration. A 51- X 0.4-cm quartz denuder tube was solution-coated with 20% w/v Al2(S04)3 and used at a very low Q (0.1 L/min). The desorption step involved heating to 500 °C for 1 min the liberated NOx was determined by a chemiluminescence monitor. Although laboratory results were attractive, field intercomparisons with a number of other methods indicated low and variable results the reasons for this discrepancy could not be identified with certainty. 

Another alternative solution to circumvent the detection and quantitation problems of classical TLC involves the use of silica-coated quartz rods, so-called chromarods. This has been pro-... 

Fig. 5 Mass change, under FIA conditions, of the MIP film (imprinted with L-aspartic acid) due to injection of a 10-mM sample of L-aspartic acid or D-aspartic acid into the KC1-HC1 carrier solution (pH = 1.6). The MIP film was deposited on a gold-coated quartz crystal resonator held at a constant potential of —0.4 V (adapted from [148])...

The strong dependence of the layer structure on the nature of the contacting electrolyte has been further investigated by using the electrochemical quartz crystal microbalance (EQCM). As discussed above in Chapter 3, this technique is based on the measurement of the frequency with which a coated quartz crystal vibrates, and this frequency can then be related to the mass of this crystal provided that the material attached to the surface is rigid. In this way, the changes that occur in thin films as a result of redox processes can be monitored. 

The dispersing element is usually a diffraction grating or an interferometer with a beamsplitter made from silicon-coated or germanium-coated quartz or calcium fluoride. 

The electrochemical quartz crystal microbalance (EQCM) has emerged as a very powerful in situ technique to complement electrochemical experiments [3-5]. Nomura and Okuhara [15] first used the quartz crystal microbalance (QCM) to detect mass changes at a metal coated quartz resonator immersed in electrolyte during electrochemical experiments. 

In the a helix there is a hydrogen bond between the carbonyl oxygen of the residue i and the amino group at residue i + 4. The helical repeat is c = 3.6 residue per turn, which gives a helical angle 6 = 360°/(3.6 residues/tum) = 100°/residue. The rise is h = 0.15 nm per residue and, therefore, the pitch is P 0.54 nm [43]. Circular dichroism (CD) measurements were performed to verify the handedness of the layers (Fig. 2b). For the CD measurements the polypeptides were deposited on 10 nm thick gold coated quartz slides which are transparent to UV radiation down to 190 nm. The CD spectra indicate a right a helix form for the LC film and a left one for the DC film. 

B. Ding, J.H. Kim, Y. Miyazaki, S.M. Shiratori. 2004. Elecfrospun nanofibrous membranes coated quartz ciystal microbalance as gas sensor for NH3 detection. Sens. Actuators B Chem, 101. pp. 373-380. 

Figure 7 shows pH dependent eleetrokinetic profiles in 7.5 mM NaCI for APS-coated quartz. The APS surface is best described by a two acid-single base model of the surface. The acid sites appear to be silanols of the same pK l as for clean glass, and the basic site an APS amine of pKb I0, which is consistent with a value obtained from thermometric enthalpy titration 24 ... 

Okahata, Y., and Ebato, H. (1992). Detection of bioactive compounds using a lipid-coated quartz-crystal microbalance. Trends Anal Chem., 11, 344-354. 

Ying, Z., Jiang, Y., Du, X., Xie, G., Yu, J., Wang, H. (2007). PVDF coated quartz crystal microbalance sensor for DMMP vapor detection. Sens. Actuators B 125 167-72. 

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