Abstract: A method employs simple procedures to speedily carry out loopback tests on devices that form a channel system of an exchange. The method is capable of quickly locating a fault in the exchange and allowing speedy maintenance work of the exchange. Also provided is an apparatus for achieving the method. The apparatus has a path setter (1-4), a loopback controller (1-3), and a tester (1-1), to test the devices of the channel system (1-2) of the exchange. The devices to be tested are arranged in replaceable units (1-21, 1-22). The path setter (1-4) simultaneously sets paths to sequentially connect the devices to be tested. The loopback controller (1-3) activates and releases loopback parts arranged in the devices to be tested. The tester (1-1) sends a test signal to the devices through the paths, receives the test signal looped back by the loopback parts, analyzes the received signal, and determines whether or not the devices are sound.

Abstract: In a redundant apparatus formed of an active unit and a stand-by unit, an upper unit is connected to the active unit though the connection controller in the normal operation, and controls the connection controller to switch the active unit over to the stand-by unit when a fault has occurred in the active unit. The connection controller includes a diagnosis portion which diagnoses the stand-by unit or the active unit with a test signal and notifies the result to the upper unit.

Abstract: In a cell exchange, cell diagnosis of continuity with respect to an individual part operating in a band width for a speed faster than a cell feeding speed is enabled by using cell test equipment with a low cell feeding speed. The method of cell diagnosis of continuity for this purpose comprises a step of setting a plurality of paths between a diagnosed unit to which the cell diagnosis of continuity is applied and the cell test equipment; a step of almost substantially concentrating cells sent from the cell test equipment through a plurality of paths at the diagnosed unit; and a step of returning cells concentrated at the diagnosed unit to the cell test equipment via one of a plurality of paths.

Abstract: A silica glass optical fiber superior in resistance to ultraviolet rays, which fiber comprises a doped silica glass cladding layer formed on a silica glass core, said silica glass core having an OH content of 10-1000 ppm, a fluorine content of 50-5000 ppm, and being substantially free of chlorine.

Abstract: A synthetic silica glass article made by hydrolyzing an alkoxysilane and thermally sintering the resulting silica; this synthetic silica glass article has a viscosity of not lower than 10.sup.10 poise at 1400.degree. C., and contains, as metallic impurities, less than 1 ppm of Al, less than 0.2 ppm of Fe, less than 0.2 ppm of Na, less than 0.2 ppm of K, less than 0.01 ppm of Li, less than 0.2 ppm of Ca, less than 0.02 ppm of Ti, less than 0.01 ppm of B, less than 0.01 ppm of P, less than 0.01 ppm of As.

Abstract: High transparency silica-titania glass beads are characterized by a linear transmittance of at least 70% as measured at a wavelength of 900 nm to 600 nm by a specific measurement method. Such beads are prepared by hydrolyzing and polycondensing a silicon alkoxide and a titanium alkoxide to form a silica-titania sol, converting the sol into a dry gel, and then grinding the gel followed by heating or heating the gel followed by grinding. A light transmisson epoxy resin composition comprising a curable epoxy resin, a curing agent, and the high tranparency silica-titania glass beads has crack resistance and high transparency in cured state. It is useful in encapsulating optical semiconductor devices.

Abstract: A synthetic silica glass article made by hydrolyzing an alkoxysilane and thermally sintering the resulting silica; this synthetic silica glass article has a viscosity of not lower than 10.sup.10 poise at 140.degree. C., and contains, as metallic impurities, less than 1 ppm at Al, less than 0.2 ppm of Fe, less than 0.2 ppm of Na, less than 0.2 ppm of K, less than 0.01 ppm of Li, less than 0.2 ppm of Ca, less than 0.02 ppm of Ti, less than 0.01 ppm of B, less than 0.01 of P, less than 0.01 ppm of As.

Abstract: The invention provides a synthetic silica glass article or tool for a dopant-diffusing process in semiconductors, which is quite satisfactory in use in respect of the outstandingly small creeping at high temperatures, by working from a silica glass block having such a creeping characteristic that the elongation under a tension of 62.5 g/mm.sup.2 at a temperature of 1250.degree. C. does not exceed 0.025% after 5 minutes.

Abstract: A method for manufacturing synthetic silica glass by reacting methyl silicate and aqueous ammonia, dispersing the silica particles produced in water, solidifying the silica by the addition of methyl silicate and heating, dehydrating, de-solventing, decarburizing and sintering the solid silica to produce a glass product. The sintered glass may be pulverized to produce a powder. The inventive method is easily carried out and avoids the high energy costs of the prior art. The glass product obtained exhibits excellent high temperature viscosity.

Abstract: A method for the preparation of a stable silica organosol in a hydrophobic organic solvent is proposed. The method comprises (a) hydrolyzing a tetraalkoxy silane, e.g. tetraethoxy silane, in an alcoholic medium in the presence of a limited amount of water and ammonia as a catalyst under controlled conditions so as to produce a silica alcosol in which the silica particles satisfy the requirements that the alkoxy groups and silanolic hydroxy groups are bonded to the silicon atoms on the surface in densities of at least 3.5 .mu. moles/m.sup.2 and not exceeding 2 .mu. mmoles/m.sup.2, respectively, and the specific surface area S given in m.sup.2 /g and the average particle diameter D given in nm of the silica particles satisfy the relationship of S.times.D.gtoreq.5000, D being 1 nm or larger, and (b) admixing the alcosol of silica particles with an organosilicon compound selected from the group consisting of the compounds represented by the general formula R.sub.4-n SiX.sub.n, (R.sub.3 Si).sub.

Abstract: The invention provides a method for the preparation of synthetic fused silica glass containing a very small amount of hydroxyl groups and has a high viscosity at high temperatures suitable for use as a material of articles for semiconductor processing at high temperatures, such as a crucible for Czochralski single crystal growing of semiconductor silicon. The method comprises hydrolyzing methyl silicate in a medium containing a specified amount of ammonia as a hydrolysis catalyst to form silica particles which are heat-treated in several successive steps.

Abstract: A magnetic recording medium including a flexible non-magnetic film base and a magnetic layer thereon consisting of magnetizable particles in a resinous binder, the magnetic layer containing or being coated with an organosilicon lubricant compound having the formula:(RCOO).sub.n Si(CH.sub.3).sub.4-nwhere R is a saturated or unsaturated aliphatic group containing from 7 to 17 carbon atoms and n is an integer in the range from 1 to 3. The friction coefficient and the tendency of the powder to come off from the magnetic layer of the magnetic recording medium are reduced.

Abstract: A magnetic recording medium including a flexible non-magnetic film base and a magnetic layer thereon which contains and/or is coated with an organosilicon compound having lubricating properties, said compound having the following formula: ##STR1## WHERE R is a saturated or unsaturated aliphatic group having from 7 to 17 carbon atoms and n is an integer from 1 to 3. The static friction coefficient and the tendency of the magnetic layer to shed powder are both substantially reduced in the improved magnetic recording medium of the present invention.