Abstract: Provided is a catalyst having high activity and yield of a target product for producing an unsaturated aldehyde and/or an unsaturated carboxylic acid and further having high mechanical strength. The catalyst is a catalyst prepared by a method in which a catalyst formulation satisfies specified atomic ratios; and in the preparation thereof, a molybdenum component raw material is an ammonium molybdate, a solvent for dissolving the ammonium molybdate is water, a bismuth component raw material is bismuth nitrate, and a solvent for dissolving bismuth nitrate is a nitric acid aqueous solution, and the weight of water for dissolving the ammonium molybdate, the weight of the nitric acid aqueous solution for dissolving the bismuth nitrate, and the acid concentration of the nitric acid aqueous solution are satisfied with specified ranges, respectively.

Abstract: Provided is a method capable of producing acrolein and/or acrylic acid, or methacrolein and/or methacrylic acid, stably in a high yield over a long period of time advantageously even in a high-load reaction, and the method is a method in which when preparing two or more kinds of catalysts having different formulations and stacking two or more layers in the axial direction of the tube, the catalysts are filled in such a manner that not only the component amount of bismuth relative to molybdenum decreases from the gas inlet side toward the gas outlet side, but also the component amount of iron relative to molybdenum increases from the gas inlet side toward the gas outlet side.

Abstract: Provided is a method capable of producing acrolein and/or acrylic acid, or methacrolein and/or methacrylic acid, stably in a high yield over a long period of time advantageously even in a high-load reaction, and the method is a method in which when preparing two or more kinds of catalysts having different formulations and stacking two or more layers in the axial direction of the tube, the catalysts are filled in such a manner that not only the component amount of bismuth relative to molybdenum decreases from the gas inlet side toward the gas outlet side, but also the component amount of iron relative to molybdenum increases from the gas inlet side toward the gas outlet side.

Abstract: Provided is a catalyst having high activity and yield of a target product for producing an unsaturated aldehyde and/or an unsaturated carboxylic acid and further having high mechanical strength. The catalyst is a catalyst prepared by a method in which a catalyst formulation satisfies specified atomic ratios; and in the preparation thereof, a molybdenum component raw material is an ammonium molybdate, a solvent for dissolving the ammonium molybdate is water, a bismuth component raw material is bismuth nitrate, and a solvent for dissolving bismuth nitrate is a nitric acid aqueous solution, and the weight of water for dissolving the ammonium molybdate, the weight of the nitric acid aqueous solution for dissolving the bismuth nitrate, and the acid concentration of the nitric acid aqueous solution are satisfied with specified ranges, respectively.

Abstract: A catalyst and a catalyst packing schedule are designed so that a relation between the raw material conversion rate at which the yield of the objective product becomes maximum and the raw material conversion rate at which a high and low correlation between maximum temperature of the catalyst layer present closest to a reaction gas inlet side Zin and maximum temperature of the catalyst layer present closest to a reaction gas outlet side Zout is reversed satisfies a specific condition of 0.5?Cmax?Ccrs?5, in which Cmax: a raw material conversion rate at which yield of the objective products becomes maximum; and Ccrs: a raw material conversion rate at which, when maximum temperature of the catalyst layer Zin is regarded as Tin, maximum temperature of the catalyst layer Zout is regarded as Tout, and the raw material conversion rate is changed, a high and low correlation between Tin and Tout is reversed.

Abstract: There is provided a process for producing aerolein, acrylic acid, methacrolein, methacrylic acid in a safe and steady manner and in high yields, which avoids a phenomenon of occurrence of an abnormal reaction attributable to the fact that the temperature at a raw material gas outlet side becomes considerably higher than the temperature at a raw material gas inlet side, with regard to the temperature of a catalyst packed in a reaction tube at vapor-phase catalytic oxidation of propylene, isobutylene, or the like.

Abstract: An object of the present invention is to provide a process for stably producing a catalyst for methacrylic acid production exhibiting high activity and high performance. The process for producing a catalyst for methacrylic acid production of the invention is characterized in that the water content of the catalyst ingredient powder for use in molding, temperature and humidity of a molding step, humidity and temperature of a baking step are individually controlled in the case where molding is performed by a coating method using an Mo—V—P—Cu-based hetero polyacid as an active ingredient and water or an alcohol and/or an aqueous solution of an alcohol as a binder.

Abstract: An object of the present invention is to provide a process for stably producing a catalyst for methacrylic acid production exhibiting high activity and high performance. The process for producing a catalyst for methacrylic acid production of the invention is characterized in that the water content of the catalyst ingredient powder for use in molding, temperature and humidity of a molding step, humidity and temperature of a baking step are individually controlled in the case where molding is performed by a coating method using an Mo—V—P—Cu-based hetero polyacid as an active ingredient and water or an alcohol and/or an aqueous solution of an alcohol as a binder.

Abstract: A three-dimensional periodical structure whose period is about 1 ?m or smaller is provided. At least two kinds of films which have two-dimensionally substantially periodical projections are successively formed in layers substantially periodical to construct structure which is substantially three-dimensionally periodical. For instance, the films are made of materials different in refractive index. The three-dimensional periodical structure whose period is about 1 ?m or smaller can be obtained by a simple fabricating method. By this structure, the propagation of a wave with a specific wavelength in many solid angular directions including several axial directions parallel to the plane and the thickness direction of the layers can be cut off.

Abstract: Disclosed is a field distribution converting optical fiber which can be massproduced and enables mutual conversion elliptical field distribution to circular field distribution or vice versa, and a laser diode module in which the field distribution converting optical fiber is used. The optical axis is assumed to be Z, either of the refractive index profiles of a core in the X and Y directions of the orthogonal three axes X, Y and Z is made into a square-law distribution profile, a slope of the refractive index profile in the corresponding X direction is made different from a slope of the refractive index profile in the Y direction. The optical axis propagating in the XZ and XY planes is caused to cyclically change in the Z direction, wherein these cycles are made different from each other to cause the cross-sectional profile of the field distribution of the optical fiber to be cyclically changed.

Abstract: A lensed optical fiber and a semiconductor laser module, characterized in that first and second optical fibers, each including a core and a cladding, are connected to one end of a single-mode fiber, including a core and a cladding, in the order named. The core of the first optical fiber has a first square-low index distribution and a length substantially equal to 1/4 of the meandering period of light propagating through the core or an odd multiple thereof. The core of the second optical fiber has a second square-low index distribution and a meandering period different from that of the first optical fiber.

Abstract: The present invention concerns a method for producing acrolein and acrylic acid by carrying out vapor phase catalytic oxidation of propylene with molecular oxygen or a gas containing molecular oxygen using a oxidation catalysts comprising Mo, Bi and Fe as an essentially element and a fixed bed multitubular reactor, which comprisesa) using a plurality of supported catalysts having different activities, which was obtained, for example, by different calcination method in the production process of the supported catalysts,b) setting a catalyst layer in a reaction tube, which is formed by dividing it into plural portions in the tube axial direction, andc) arranging the aforementioned plural supported catalysts in such order that the activity becomes high toward the outlet from the inlet of the material gas in the reaction tube axial direction.

Abstract: A device which allows easy observation of discrepancies between the upper and lower jaw comprises an upper bow (100) and a lower bow (200) which separately hold in place an upper jaw model (UM) and a lower jaw model (LM) prepared based on impressions and position these upper and lower jaw models (UM) and (LM) opposite to each other, checker pins (310) in the upper bow (200) which are positioned at a location corresponding to the opening/closing axis of the upper jaw model (UM) and lower jaw model (LM) and along the opening/closing axis, and checker plates (300) in the upper bow (100) positioned in such a manner that their outer surfaces (306) are perpendicular to the opening/closing axis and adjacent to the tips of the checker pins (310).

Abstract: A catalyst having a high activity and mechanical strength and a process for preparing it are provided. The catalyst comprises molybdenum, vanadium, copper and antimony as essential components. The peak in X-ray diffractometry of the catalytically active component with Cu--K.alpha. line is largest at 22.2.+-.0.30.degree. (2.theta.).

Abstract: A catalyst for the production of unsaturated aldehyde and unsaturated acid, obtained by loading a catalytically active component on a carrier and calcining the loaded catalyst, characterized by an average particle diameter of the catalyst of 4 to 16 mm, an average particle diameter of the carrier of 3 to 12 mm, a calcining temperature of 520 to 600.degree. C. and an amount of the catalytically active component loaded on the carrier of 5 to 80% by weight ?weight of the catalytically active component)/(weight of the catalytically active component+weight of the carrier+weight of a strength improver)!, and a process for producing unsaturated aldehyde and unsaturated acid with the catalyst.

Abstract: An optical isolator for preventing reflection-returned light from entering back into the emitter of an optical system such as an optical fiber communication or an optical disc input/output device, using semiconductor laser. The polarization-independent optical isolator includes a light-emitting side optical fiber having a diameter of a core expanded to give a mode field diameter at an end face of 20 to 50 .mu.m, a light-incident side optical fiber having a diameter of a core expanded to give a mode field diameter at an end face of 20 to 50 .mu.

Abstract: A lensed-fiber including a single-mode fiber having a core and a cladding, a coreless fiber having a coreless isotropic refractive index and a convex surface at a first end thereof, and a square-law index fiber having a square-law index profile. The square-law index fiber is positioned between the single-mode fiber and the coreless fiber so as to connect an end of the single-mode fiber to a second end of the coreless fiber. The lensed-fiber may be arranged in a optical module facing an optical semiconductor element which emits a light beam to be propagated through the single-mode fiber.

Abstract: A simple and excellent process for the regeneration of heteropolyacid catalysts can be provided. A heteropolyacid catalyst, e.g. a phosphomolybdic acid catalyst, whose activity has been lowered can be regenerated by dissolving and/or suspending it in an aqueous medium and then treating with an inorganic ion-exchange material, e.g. crystalline antimonic acid.

Abstract: An optical fiber having a lens formed at an end thereof comprises a fiber body including a core and a cladding, and an incident light guide portion having a uniform refractive index and integrally formed at an end portion of the fiber body, wherein the incident light guide portion has a convex surface, and the core has a distal end located within the incident light guide portion at a position close to a focal point of the incident light guide portion.

Abstract: An optical isolator comprising an optical isolator unit having a structure depending on a plane of polarization of incident light, a first optical system for splitting the incident light into two polarized components for incidence on the optical isolator unit, and a second optical system for combining the two polarized components emerging from the optical isolator unit. The optical isolator can thus manifest an excellent effect of isolation without considering the plane of polarization of the incident light.