Thin applications

W Addicks, G Flynn, N Weiner, C Chiang. Drug transport from thin applications of topical dosage forms Development of methodology. Pharm Res 6 377, 1988. 

The gloss of a pigmented system is a function not only of the degree of pigment dispersion but also frequently of the particle size distribution (Sec. 1.6.5). This is a common phenomenon in very thin applications, such as in offset printing, which produces layers less than 1 pm thick. 

Franks, J. Ghander, A.M. Saddle Field Ion Source of Spherical Configuration for Etching and Thinning Applications. Vacuum 1974,24,489-491. 

Bench coaters are roughly 20 to 35 percent faster than hand-brushing and cut waste by up to 20 to 35 percent. They start to be useful at rates of 200 pieces per day and can reach 12,000 pieces per day. Roller sizes range from 4 to 26 in, and they come with various surfaces from smooth for thin applications to increasingly coarse for heavier adhesive layers. 

Nowadays, there are many HALS stabilizers commercial of which the majority is based on 2,2,6,6-tetra-methyl-4-piperidinyl moieties. The first commercial type (LMW-HALS-1) is relatively low in molecular weight, which caused that due to its high volatility it is not suitable for thin applications. To overcome this problem oligomeric HALS types were developed. One of the drawbacks of the piperidinyl moiety of HALS stabilizers is that it is basic causing that it can react with acids and forms a not stabilizing salt. Consequently, the effectiveness of HALS in systems where acids are present or can be formed is limited. To beat this problem less basic HALS types as, for example, N-O-R types were developed. 

Addicks, W.J., Hynn, G.L., Weiner, N., and Chiang, C.-M. (1988). Drag transport from thin applications of topical dosage forms development of methodology. Pharmaceutical Research, 5, 377-382. 

P-FRs have both negative chemical and mechanical efferts in the resin, limiting their applications. For example, they are not usually used in thin applications, or in water-handling applications, because of their solubility and extraction tendencies. Moreover, as with mineral FRs, P-FRs tend to inaease modulus and heat-deflection temperature (HDT), while lowering impart strength and other mechanicals [1-1, 5-11, 5-13). 

The form that the adhesive takes (liquids, mastics, hot melts, etc.) can have a bearing on how and where they are used. The anaerobics, which can give some very high bond strength and are usable with all materials except polyethylene and fluorocarbons, are dispensed by the drop. A thin application of the anaerobics is said to give better bond strength than a thick application. 

Copperhead. A fault (reddish-brown spots) liable to appear in the ground-coat during vitreous enamelling the spots are exposed areas of oxidized base metal. Causes include boiling from the base-metal, inadequate metal preparation, very thin application of enamel, and the presence of acid salts in the enamel slip. 

Flux must be heated to a temperature to allow the best reactive conditions without drying out or denaturing. For the sake of economy and cleaning, a thin application is necessary and should be confined to the bonded site(s) of interest. 

The results obtained with the two methods confirm the measured data with a good precision, with less computational time for the specialised code than the general code. This validation on three representative test bloeks can lead to many applications of modelling of the thin-skin regime. 

Gammagraphic weld inspection in the lower range of steel thicknesses has been done with Iridium and Ytterbium isotope sources throughout the past. The large majority of applications has been using Iridium due to the unfavourable economical parameters of Ytterbium, obviously with non-optimal results at thin wall inspections. 

Another important application area is the non-destructive defectoscopy of electronic components. Fig.2a shows an X-ray shadow image of a SMC LED. The 3-dimensional displacement of internal parts can only be visualized non-destructively in the tomographic reconstmction. Reconstructed cross sections through this LED are shown in Fig.2b. In the same way most electronic components in plastic and thin metal cases can be visualized. Even small electronic assemblies like hybrid ICs, magnetic heads, microphones, ABS-sensors can be tested by microtomograpical methods. 

Based upon a piezoelectric 1-3-composite material, air-bome ultrasonic probes for frequencies up to 2 MHz were developped. These probes are characterized by a bandwidth larger than 50 % as well as a signal-to-noise ratio higher than 100 dB. Applications are the thickness measurement of thin powder layers, the inspection of sandwich structures, the detection of surface near cracks in metals or ceramics by generation/reception of Rayleigh waves and the inspection of plates by Lamb waves. 

The Institute has many-year experience of investigations and developments in the field of NDT. These are, mainly, developments which allowed creation of a series of eddy current flaw detectors for various applications. The Institute has traditionally studied the physico-mechanical properties of materials, their stressed-strained state, fracture mechanics and developed on this basis the procedures and instruments which measure the properties and predict the behaviour of materials. Quite important are also developments of technologies and equipment for control of thickness and adhesion of thin protective coatings on various bases, corrosion control of underground pipelines by indirect method, acoustic emission control of hydrogen and corrosion cracking in structural materials, etc. 

Transmission electron microscopy (TEM) can resolve features down to about 1 nm and allows the use of electron diffraction to characterize the structure. Since electrons must pass through the sample however, the technique is limited to thin films. One cryoelectron microscopic study of fatty-acid Langmuir films on vitrified water [13] showed faceted crystals. The application of TEM to Langmuir-Blodgett films is discussed in Chapter XV. 

For bulk structural detemiination (see chapter B 1.9). the main teclmique used has been x-ray diffraction (XRD). Several other teclmiques are also available for more specialized applications, including electron diffraction (ED) for thin film structures and gas-phase molecules neutron diffraction (ND) and nuclear magnetic resonance (NMR) for magnetic studies (see chapter B1.12 and chapter B1.13) x-ray absorption fine structure (XAFS) for local structures in small or unstable samples and other spectroscopies to examine local structures in molecules. Electron microscopy also plays an important role, primarily tlirough unaging (see chapter B1.17). 

The application of RBS is mostly limited to materials applications, where concentrations of elements are fairly high. RBS is specifically well suited to the study of thin film stmctures. The NMP is usefiil in studying lateral inliomogeneities in these layers [30] as, for example, in cases where the solid state reaction of elements in the surface layers occur at specific locations on the surfaces. Other aspects, such as lateral diffusion, can also be studied in tluee-dimensions. 

This expression is the sum of a transient tenu and a steady-state tenu, where r is the radius of the sphere. At short times after the application of the potential step, the transient tenu dominates over the steady-state tenu, and the electrode is analogous to a plane, as the depletion layer is thin compared with the disc radius, and the current varies widi time according to the Cottrell equation. At long times, the transient cunent will decrease to a negligible value, the depletion layer is comparable to the electrode radius, spherical difhision controls the transport of reactant, and the cunent density reaches a steady-state value. At times intenuediate to the limiting conditions of Cottrell behaviour or diffusion control, both transient and steady-state tenus need to be considered and thus the fiill expression must be used. Flowever, many experiments involving microelectrodes are designed such that one of the simpler cunent expressions is valid. 

Equations (5,61) and (5.62) can be used to derive a pressure potential equation applicable to thin-layer flow between curved surfaces using the following procedure. In a thin-layer flow, the following velocity boundary conditions are prescribed ... 

To prepare crystalline monoperphthalic acid, place the thoroughly dry ethereal solution (4) in a distilling flask equipped with a capillary tube connected with a calcium chloride or cotton wool drying tube, and attach the flask to a water pump. Evaporate the ether without the application of heat (ice will form on the flask) to a thin syrup (about 150 ml.). Transfer the syrup to an evaporating dish, rinse the flask with a little anhydrous ether, and add the rinsings to the syrup. Evaporate the remainder of the ether in a vacuum desiccator over concentrated sulphuric acid about 30 g. of monoperphthalic acid, m.p. 110° (decomp.), is obtained. 

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