Abstract: Each of a first clad region (12) and a second clad region (13) has holes (12a, 13a) which have identical diameters and are periodically formed so that the first clad region (12) and the second clad region (13) each have an effective refractive index lower than a refractive index of a core region (11), the effective refractive index of the first clad region (12) being lower than that of the second clad region (13).

Abstract: Each of a first clad region (12) and a second clad region (13) has holes (12a, 13a) which have identical diameters and are periodically formed so that the first clad region (12) and the second clad region (13) each have an effective refractive index lower than a refractive index of a core region (11), the effective refractive index of the first clad region (12) being lower than that of the second clad region (13).

Abstract: A coated optical fiber identifying apparatus is provided, which can realize coated optical fiber identification for a single mode optical fiber with holes. The coated optical fiber identifying apparatus comprises a grating forming tool 20 for forming a grating by applying a force to an optical fiber with a plurality of protrusions 23, and a photo detector 30 for detecting leak light generated in the optical fiber 1, wherein the plurality of the protrusions 23 are arranged in a period ? within a range of 0.24 mm to 0.75 mm.

Abstract: A coated glass fiber for light transmission consisting of a glass fiber for light transmission and at least one coating layer made of a UV-curing resin, wherein an outermost layer of the coating layer is made of a UV-curing resin having a Young's modulus of at least 100 kg/mm.sup.2 and a change of a cure shrinkage degree of 1% or less after a Young's modulus reaches one tenth of an end Young's modulus, which has good lateral pressure characteristics and low transmission loss.

Abstract: An optical fiber cable provided with a grooved spacer having on its outer circumference at least one SZ-spiral groove formed continuously along its longitudinal direction and at least one optical fiber tape accommodated in the groove of the grooved spacer, wherein the inverting angle, showing the rotational angle in the circumferential direction of the grooved spacer from one inverting portion of the SZ-spiral groove of the grooved spacer to the next inverting portion, is at least 180.degree.

Abstract: A light transmitting optical fiber having at least one coating layer of an ultraviolet curing resin on an outer surface of the fiber, in which the ultraviolet curing resin used in an outermost layer has a Young's modulus of at least 100 kg/mm.sup.2 and an elongation of at least 30%.

Abstract: There is disclosed an optical waveguide comprising a core portion made of a light propagating material and a cladding portion, a first dopant and a second dopant being induced into said core portion, the first dopant having a function of increasing a refractive index of the light propagating material and having a first thermal diffusion coefficient to said light propagating material, the second dopant having a function of decreasing the refractive index of said light propagating material and having a second thermal diffusion coefficient to the light propagating material larger than the first thermal diffusion coefficient under a predetermined temperature.

Abstract: A method for installing and recovering transmission cable. A termination box has a stationary winding barrel having a central axis, and a transmission cable guide rotatably coupled to the stationary winding barrel for guiding a transmission cable onto and from the stationary winding barrel by being rotated around the central axis. Various methods show the step for winding and unwinding transmission cable from the termination box; as well as, use of the termination box in conjunction with a strength wire to install transmission cables between a transmission supply point and a transmission receiving point or points.

Abstract: A redundant length treatment mechanism for an optical fiber which is stored in an optical cable and has one end connected to an optical connector, includes a storage case in which a redundant part of the optical fiber exposed from the optical cable is stored while wound up in a loop form, a bent form or an S-shape form, the storage case having a draw-out portion through which one end portion of the looped optical fiber is drawn out, and curvature restricting means comprising a pair of stoppers secured to the optical fiber for restricting radius of curvature of the optical fiber stored in a loop form in the storage case.

Abstract: In a CATV receiver or television receiver channel selecting apparatus provided with a controlling device wherein, on the basis of a channel-up or channel-down channel selecting operation, data corresponding to local oscillation frequencies of the respective channels are output, a tuning voltage is prepared by using these data and the local oscillation frequency of the tuner is controlled, the above mentioned controlling device is provided with a device for memorizing the information as to whether it is inhibited or permitted to select the respective channels at the time of the channel-up or channel-down channel selection so as to memorize the common channel selection inhibiting information for a plurality of channels not allowed to exist simultaneously and to be ablve to save the memory capacity of the memory (RAM) of the channel selecting microcomputer; and further, a device for quickly searching the input signal frequency of the channel without a mis-operation in the case of selecting an objective channel a

Abstract: A mixture of a carboxymethylated yeast with a higher fatty acid and the like is prepared, and a water-soluble polyvalent metal salt of an inorganic acid is added to the mixture in the presence of water. The resulting composition has an oil-coagulating effect.

Abstract: An oil adsorbent comprising natural fibers the surface of which is coated with a water-repellent paraffin layer which is in turn coated with an elastic rubber layer. The adsorbent is manufactured by treating the surface of the natural fibers with a paraffin emulsion, drying the fibers to form a water repellent paraffin layer thereon, treating the product with a latex, and then curing the latex to form an elastic rubber layer on the paraffin layer. The oil adsorbent has such advantages that it floats on the surface of water stably for a long period of time retaining its original form, that the contained paraffin is not back extracted by adsorbed oil and that it does not cause any trouble on burning.

Abstract: New adsorbents comprising granules of a mixture of nitrohumic acid and one r more proteins. These adsorbents are utilizable effectively for adsorbing heavy metals and oils contained in water. They are produced advantageously by either a process wherein a mixture of nitrohumic acid and a protein is kneaded with an aqueous solution of alkali and the kneaded mixture is first subjected to an acid treatment and then shaped into granules, or a process wherein nitrohumic acid and a protein are dissolved in an aqueous solution of alkali, the solution is acidified to form a precipitate and then the precipitate is separated and shaped into granules. The granular products thus obtained can be further improved in mechanical strength by means of a heat treatment.

Abstract: An adsorbent of nitrohumic acid series with an improved alkali-resistance is prepared by insolubilizing calcium nitrohumate, kneading the insolubilized product with a water-soluble polyacrylamide in the presence of water, shaping the mixture into a desired form and then subjecting it to a heat treatment followed by an acid treatment. The adsorbent thus obtained can effectively be used for removing heavy metals from an alkaline effluent without causing any deterioration of adsorptive quality and coloration of the effluent.

Abstract: A process for removing heavy metal ions from aqueous solutions with an adbent comprising granules of a mixture of nitrohumic acid and at least one binder selected from the group consisting of a carboxyl group-containing polymeric compound and a water-insoluble salt thereof. These heavy metal adsorbents are produced advantageously by either a process wherein a mixture of nitrohumic acid and a carboxyl group-containing polymeric compound is kneaded with an aqueous solution of alkali and the kneaded mixture is first subjected to an acid treatment and then shaped into granules, or a process wherein nitrohumic acid and a carboxyl group-containing polymeric compound are dissolved in an aqueous solution of alkali, the solution is acidified to form a precipitate and then the precipitate is separated and shaped into granules. The granular products thus obtained can be further improved in mechanical strength by means of a heat treatment.