Record, recording discs

Discs Discs of nickel electroformed on to mandrels bearing grooves modulated with recorded sound have been used for many years for stamping sound recording discs. This process has been adapted and refined for the manufacture of digital records, including video discs . Video disc stampers must be hard, stress-free, and flat to within 0.1 m results of a short investigation directed towards these requirements have been reported ". 

The order in which the treatments were to be applied was programmed into the computer, and the apparatus then operated unattended until it was time to insert a fresh data recording disc disc or to change the specimens. A complete series of treatments on a group of three specimens required about 6 weeks. 

NOTE 1 SECTION 35 is to be used to record disc sensitivities for clinical applications (eg., the methods of Bauer et. al., 1966, commonly referred to as Kirby-Bauer or Bauer-Kirby Methods). Other tests of antimicrobial sensitivity or resistance should be coded under SECTION 19/40.]... 

Although thermoset and photoset materials are certainly among the candidates for specific optical media substrates, such as large recordable discs, the discussion will be restricted here to thermoplastics. Suitable candidates are then found among amorphous polymers with excellent optical transparency and an acceptable mix of other properties. 

Gramophone (Emile Berhner) A major contribution to the music recording industry, Berliner s gramophone uses flat record discs for recording sound. Berliner goes on to produce a helicopter prototype (1906-1923). 

Optical media 32 Compact Discs, CDs and DVDs, Blu-Ray discs, digital and holography discs, innovative data storage technology (e.g., near-field recording discs)... 

Uses Surfactant for surf, pretreatment of magnetic recording discs... 

Shellac is a varnish of animal origin, and its composition is quite different from that of plant resins. It is secreted by the female lac bug in India and Thailand and has been used as a stain, a varnish, and in artifacts such as 78 rpm record discs. While it has been replaced by man-made polymers for most uses, it is still used in French polishing of furniture and on musical instruments. Hydrolysis gives a mixture of hydroxy acids such as aleuritic acid, R-6-hydroxyhexadecanoic acid, jalaric acid, and the colorant laccaic acids (Figure 21.30). The material is composed of low molecular weight, cross-linked polyesters. 

For many years vinyl chloride-vinyl acetate copolymers had two main uses, in flooring compositions and for long playing gramophone records. Whereas the former application remains strong, the use in gramophone records has dropped sharply, particularly since the widespread acceptance of polycarbonate-based compact discs. 

There is no entirely satisfactory way of measuring flow. In the BS 2782 flow cup test an amount of moulding powder is added to the mould to provide between 2 and 2.5 g of flash. The press is closed at a fixed initial rate and at a fixed temperature and pressure. The time between the onset of recorded pressure and the cessation of flash (i.e. the time at which the mould has closed) is noted. This time is thus the time required to move a given mass of material a fixed distance and is thus a measure of viscosity. It is not a measure of the time available for flow. This property, or rather the more important length of flow or extent of flow, must be measured by some other device such as the flow disc or by the Rossi-Peakes flow test, neither of which are entirely satisfactory. Cup flow times are normally of the order of 10-25 seconds if measured by the BS specification. Moulding powders are frequently classified as being of stiff flow if the cup flow time exceeds 20 seconds, medium flow for times of 13-19 seconds and soft flow or free flow if under 12 seconds. 

The number of rotations of the disc is registered and can be recorded on a dial. As noted above, the voltages and currents energizing the coils are the normal system voltages unless these are too large for convenience, in which case voltage and current transformers are used as appropriate. 

Aluminium is widely applied for decorative and protective requirements, while cadmium , zinc and titanium have been applied to ferrous materials chiefly for their protective value. The method finds particular application in the plating of high-tensile steels used in aviation and rocketry, car fittings and lamp reflectors, and gramophone record master discs, as well as in the preparation of specimens for electron microscopy and in rendering insulated surfaces electrically conducting, e.g. metallising of capacitors and resistors. 

Figure 2.36 Resonance Raman spectra of (a) Rh2(l602)CMe4(PPh3)2 (b) Rh2(l802)CMe,((PPh )2 (c) Rh2(l602)C(CD3)4CPPh3)2. Recorded as KC1 discs at 80K,L = 363.8nm. (Reprinted with permission from J. Am. Chem. Soc., 1986,108, 518. Copyright (1986) American Chemical Society.)...

According to Haber (loc. cit., p. 131) the results of Langen are probably correct to 3 per cent, even at 2,000°. Pier, in his recent explosion experiments, has shown, however, that the maximum pressures were not obtained by the previous observers, on account of the oscillations of their manometers, He used a steel plate with very high frequency of vibration, and registered the distortion by reflecting a beam of light from a mirror attached to the manometer disc on to a revolving drum of sensitised paper. The recorded curves show a well-defined maximum pressure, and his results are probably accurate to 1 per cent. Values of Gv ... 

Goglia, P. R., Berkowitz, J., Hoehn, J., Xidis, A., and Stover, L., Diamond-Like Carbon Applications in High Density Hard Disc Recording Heads," Diamond Rel. Mat., Vol. 10, 2001, pp. 271-277. 

UV diffuse reflectance spectra of the titanates were obtained with a JASCO UVIDEC-660 spectrophotometer using a sintered alumina disc as a reference. Raman spectra were recorded at room temperature on a JASCO NR-1100 spectrometer. 

FT-IR spectra were recorded at RT on a Perkin-Elmer 1760-X spectrophotometer equipped with a cryodetector, at a resolution of 2 cm-" (number of scans -100). In the 1070-960 cm- region, band integration and curve fitting were carried out by Curve fit, in Spectra Calc. (Galactic Industries Co.). Powdered materials were pelleted in self-supporting discs of 25-50 mg cm-2 and 0.1-0.2 mm thick, placed in an IR cell allowing thermal treatments in vacuo or in a controlled atmosphere. 

In a typical study of conductivity. Cook (1982) used a cell consisting of two platinum disc electrodes, 12 mm in diameter and 1-5 mm apart. The setting AB cement was examined in this cell which had been calibrated using a standard solution of0 02 M potassium chloride. Plots were recorded of spedfic conductance against time for each of the setting cements. For zinc polycarboxylate there was found to be a rapid drop in spedfic conductance about 10 minutes after the start of mixing. This behaviour was consistent with the replacement of relatively mobile protons by significantly less mobile zinc ions in the polycarboxylate chain. Con-... 

Fungicidal activity was determined by the disc method and zones of inhibition were recorded by measuring the diameter (mm) of the inhibition zone. Yeast cultures (S. cerevisiae) showed growth inhibition (clear area surrounding disc) by sediment extracts from all stations when compared to control discs. HPLC analysis of sediment extracts showed more than 20 components in the migration profile of each station. Of these components, a fraction demonstrated to possess cytolytic activity in the crude extract (Ve = 24 ml) was present in all stations when compared to the migration profile of the active fraction (Figure 2). 

Iowa Drug Information Service. A bibliographical database with access to full text, IDIS [98] provides access to the therapeutic and clinical pharmaceutic English language journal literature from 17 countries. FDA Summary Basis of Approval documents are indexed and available in full text. Updated monthly, the database contains over 450,000 records from 1966 forward with bibliographic citation, keyword indexes, and, for over 60% of citations, the author s abstract. IDIS is commercially available in microfiche, compact disc, and web formats and via DataStar, DIALOG. 

---