Tandem coating

The procedure to evaluate adhesion strength of plasma-sprayed hydroxyapatite coatings has been described earlier. The presence of a thin plasma-sprayed titania bond coat (see Chapter 6.3.2.2) considerably enhances the adhesion strength to a Ti6Al4V substrate of titania/HAp tandem coatings compared to HAp coatings without a bond coat. 

The tandem coating line seen in Lig. 8.2 can be used to reduce the cost of producing products that require both laminating and coating, such as a paper/poly-ethylene/foil/sealant type of structure. If this product is made in two passes through the machinery, the cost is higher because of the increased cost of handling the materials twice and the increased start-up and shut-down waste. 

Figure 9.11 shows a tandem coating machine. Here, from each side the material is fed, coated separately, and then combined in a lamination process in the middle of the machine. This process is used to produce laminates for insulation applications. 

In most coatiag operatioas a single layer is coated. Whea more than one layer must be appHed one can make multiple passes, or use tandem coaters where the next layer is appHed at another coatiag statioa ioimediately foUowiag the dryer sectioa for the previous layer, or a multilayer coatiag statioa can be used. Slot, extmsion, sHde, and curtain coaters are used to apply multiple layers simultaneously. SHde and curtain coaters can apply an unlimited number of layers simultaneously, whereas slot and extmsion coaters are limited by the complexity of the die internals. 

The top and the bottom x-ray detector each contain a multiplier phototube coated with phosphor. This tube compares the intensity of the x-ray beam entering the detector with that of the light from the reference standard, a discharge lamp. The reference beam is part of a circuit that maintains the x-ray source at constant intensity. The deviation wedge comes to rest when the intensities of the transmitted x-ray beams stand in a predetermined ratio. At this point, the unbalance in the servo system has been compensated, and the position of the deviation wedge consequently indicates the thickness of the strip. In 1955, this application was made fully automatic that is, the unbalance (or error signal) just mentioned was used to readjust tandem cold reduction mills of the United States Steel Corporation. Automatic control proved significantly more effective than manual control. 

Figure 2.7 Activity test of an uncoated fused silica capillary after deactivation with poly(phenyliaethylhydrosiloxane), (A), and before deactivation, (B). Precolunn 15 x 0.20 m I.D. coated with SE-54. Test columns 10 a x 0.20 I.D. The column tandem was programmed from 40 to I80 c at a C/min after a 1 min isothermal hold with a hydrogen carrier gas velocity of 50 cm/s. The test mixture contained 10 n-decane, Cg-NH = l-aminooctane, PY 3,5-dimethylpyrimidine, C 2 n-dodecane, - 1-amlnodecane, DMA ...

C.W. Huck, M.R. Buchmeiser and G.K. Bonn, Fast analysis of flavonoids in plant extracts by liquid chromatography-ultraviolet absorbance detection on poly(carboxylic acid)coated silica and electrospray ionization tandem mass spectrometric detection. J. Chromatogr.A 943 (2002) 33-38. 

When using PFT with a neutral selector, it is quite difficult to avoid any entrance of the chiral selector into the ionization source, particularly at a high pH, where EOF is important. The use of BGE at low pH and/or coated capillary to minimize EOF is therefore mandatory. However, the coaxial sheath gas, which generally assists the ionization process, leads to an aspirating phenomenon of the chiral selector in the MS direction. Javerfalk et al. were the first to apply PFT with a neutral methyl-/i-CD for the separation of racemic bupivacaine and ropivacaine with a polyacrylamide-coated capillary and an acidic pH buffer (pH 3). Cherkaoui et al. employed another neutral CD (HP-/1-CD) with a PVA-coated capillary for the analysis of amphetamines and their derivatives. To prevent a detrimental aspiration effect, analyses were carried out without nebulization pressure. Numerous other studies presented excellent results such as the enantioselective separation of adrenoreceptor antagonist drugs using tandem mass spectrometry (MS/MS) the separation of clenbuterol enantiomers after solid-phase extraction (SPE) of plasma samples or the use of CD dual system for the simultaneous chiral determination of amphetamine, methamphetamine, dimethamphetamine, and p-hydroxymethamphetamine in urine. 

The use of tandem denuders, each with the same coating, permits at least partial correction for these sources of error in HN03 measurement. Species retained with low efficiency on carbonate coatings (e.g., NO and PAN) are collected in about equal amounts by successive denuders. If it is assumed that oxidation during and subsequent to sampling occurs equally on successive denuders as well as in their corresponding extracts, the N03 from the second denuder extract can be subtracted from that in the front denuder extract to obtain a measure of atmospheric HN03. However, this technique does not correct for the efficient retention (and subsequent oxidation) of atmospheric or artifact HONO. 

The efficiency of HN03 collection with a single annular denuder should be confirmed by each user with a known source of HN03, regardless of denuder coating used. On the basis of laboratory studies, Ferm and Sjodin (42) reported a technique that can be used to correct simultaneously for penetration of HN03 through the first of tandem denuders as well as for artifact N03" due to atmospheric species retained with low efficiency. 

A layer of transparent lacquer or PVC plastisol may be superimposed as desired to protect print and to control the gloss of the finish. A vinyl-acrylic lacquer may be applied in tandem with colour printing or, say, a clear plastisol coating by screen printing, usually in the last stage as the material passes to the oven for fusion and expansion. 

The comparison demonstrates the potential of the a-Si H/pc-Si H tandem cell technology on textured ZnO coated glass substrates for highly efficient large area thin film solar modules. However, the transfer of the technology... 

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