Abstract: An object of the present invention is to provide a high-porosity, high-strength porous silicon nitride having great tolerance with respect to strain and stress, and a method for producing the same, and the present invention relates to a high-porosity, high-strength porous silicon nitride having great tolerance with respect to strain and stress, characterized in that rodlike grains of silicon nitride with a minor diameter of 0.5 to 10 .mu.m and an aspect ratio of 10 to 100 are oriented in a single direction, and the rest of the structure other than the rodlike grains consists solely of pores with a porosity of 5 to 30%, and further the above-mentioned porous silicon nitride is produced by mixing rodlike particles of silicon nitride with a minor diameter of 0.5 to 10 .mu.

Abstract: This invention relates to a method for forming a titanium alloy by powder metallurgy, which comprises the processes of mixing uniformly a powder of titanium or an alloy thereof with a low-melting point metal or alloy powder, injecting the mixture into a press forming die, then press forming them under heating to a temperature near and over the melting point of the low-melting point metal, or to a temperature between the liquidus and the solidus of the low-melting point alloy, or to a temperature near and over the liquidus to obtain the targeted compact, and holding this compact in the pressurized state to cause the molten low-melting point metal or alloy to infiltrate the powder grain boundary of the titanium or alloy thereof, and then sintering the compact thus obtained in an inert atmosphere or a vacuum to diffuse the titanium or alloy thereof and the low-melting point metal or alloy into each other and to make alloys of them.

Abstract: The present invention relates to a method for producing an Sr--Bi--Ta or Nb-based composite alkoxide with the structure of an atomic arrangement controlled, having a metal atomic ratio of Sr:Bi:Ta or Nb=1:2:2, characterized in that an Sr alkoxide (Sr(OR).sub.2) prepared from an Sr metal is allowed to react with a Bi alkoxide (Bi(OR).sub.3) in alcohol to produce an Sr--Bi double alkoxide (Sr?Bi(OR).sub.4 !.sub.2), and subsequently the alkoxide is allowed to react with a Ta alkoxide (Ta(OR).sub.5) or an Nb alkoxide (Nb(OR).sub.5).

Abstract: The present invention provides silicon nitride ceramics having high thermal conductivity and a method for production thereof. This invention relates to a method for producing a silicon nitride sintered body having a microstructure with silicon nitride crystals oriented uniaxially and exhibiting high thermal conductivity of 100 to 150 W/mK in the direction parallel to the orientation direction of the crystals, which comprises of preparing a slurry by mixing a mixed powder of a sintering auxiliary, beta-silicon nitride single crystals as seed crystals and a silicon nitride raw powder with a dispersing medium, forming the slurry by tape casting or extrusion forming, calcining the formed silicon nitride body with beta-silicon nitride single crystals oriented parallel to the casting plane to remove the organic components, densifying it by hot pressing and the like if required, and further annealing it at 1700 to 2000.degree. C. under the nitrogen pressure of 1 to 100 atmospheres.

Abstract: The present invention provides a die for superplastic forming of titanium-based alloy with high-workability, which is inexpensive and easy to handle, and has detailed shape-reproducibility and no reactivity with titanium-based alloy to be processed, and has excellent accordance with it in a thermal expansion coefficient. This invention relates to a die for superplastic forming of titanium-based alloy characterized by comprising quartz, cristobalite and calcium silicate. The above die for superplastic forming of titanium-based alloy is produced by kneading a mixed powder of quartz and cristobalite, together with a binder containing a plaster additive of less than 30 weight % based on the total amount with water, forming the mixture, drying the formed product and sintering it in the atmosphere to convert the plaster additive into calcium silicate.

Abstract: The present invention relates to a silicon nitride sintered body having a remarkably increased strain-to-fracture, a low elasticity and high strength, characterized by consisting of a layered structure of alternating porous silicon nitride layers 1 to 1000 .mu.m thick with a porosity of 5 to 70 volume % and dense silicon nitride layers 1 to 1000 .mu.m thick with a porosity of less than 5 volume %, being layered as materials with optional tiers. In addition, this invention relates to a method for producing the silicon nitride sintered body as described above, which comprises of forming dense layers and porous layers by sheet casting or extrusion forming so as to prepare the layers to be capable of 1 to 1000 .mu.m thick after sintering, stacking them to obtain layered materials with optional tiers and sintering them at 1600.degree. to 2100 .degree. C. under a nitrogen atmosphere.

Abstract: A semiconductor silicon single crystal wafer having a flat surface plane in a crystallographic orientation slightly deviated from the (001) axis was subjected to an oxidation treatment to form an oxidized surface film to such an extent that ordered stepwise level differences are formed in the interface between the oxidized surface film and the silicon surface followed by removal of the oxidized surface film with a hydrofluoric acid solution containing hydrogen chloride and having a pH not higher than 1 in such a fashion that the oxidized surface film is dissolved away by dipping the wafer in the acid solution while keeping equivalency relative to each of the stepwise level differences so that the wafer surface can be concurrently cleaned and flattened in an atomic level as evidenced by the scanning tunneling microscopic photographs.

Abstract: A process for removing nitrogen oxide from exhaust is disclosed, comprising contacting exhaust containing nitrogen oxide with an alumina catalyst which contains not more than 0.5% by weight of an alkali metal and/or an alkaline earth metal and has a total pore volume of from 0.48 to 1.2 cm.sup.3 .multidot.g.sup.-1 with 0.26 to 0.6 cm.sup.3 .multidot.g.sup.-1 of the total pore volume being formed of pores of not greater than 80 .ANG. or has a volume of pores formed of pores of not greater than 60 .ANG. of from 0.06 to 0.2 cm.sup.3 .multidot.g.sup.-l and which may have supported thereon tin in an oxidative atmosphere containing excess oxygen in the presence of a hydrocarbon or an oxygen-containing organic compound.

Abstract: A vic-dichloro-fluorinated alkene of the formula: R.sup.1 --CCl.dbd.CCl--R.sup.2, and a fluorinated alkane of the formula: R.sup.1 --CR.sup.3 R.sup.4 --CR.sup.5 R.sup.6 --R.sup.2, wherein each of R.sup.1 and R.sup.2 independently represents a perfluoroalkyl group or both of R.sup.1 and R.sup.2 form together a perfluoroalkylene group, and R.sup.3, R.sup.4, R.sup.5 and R.sup.6 independently represent hydrogen or fluorine, are produced from an inexpensive raw material. More specifically, hexachlorocyclopentadiene is reacted with gaseous chlorine using an antimony catalyst, and then the reaction product is reacted with hydrogen fluoride to give 1,2-dichlorohexafluorocyclopentene. Thus-obtained compound is either (i) hydrogenated, or (ii) treated with a fluorinating agent to substitute the chlorine atoms by fluorine atoms, and then hydrogenated, to give the intended fluorinated alkane.

Abstract: The object of the invention is to provide a novel process for epoxidation of perfluoro-olefins.This invention relates to a process for epoxidizing a perfluoro-olefin, characterized by employing a tertiary amine N-oxide represented by the general formula (I): ##STR1## (wherein R.sup.1, R.sup.2 and R.sup.3 each is a straight-chain or branched alkyl group having 1 to 10 carbon atoms, a lower alkyl group having 1 to 3 carbon atoms, or an aromatic group which may have a nitro group or a cyano group as a substituent; provided that all of R.sup.1, R.sup.2 and R.sup.3 are selected from the above alkyl groups, R.sup.1, R.sup.2 and R.sup.3 may combine with one another directly or through oxygen atoms or nitrogen atoms to form a cyclic compound of 5-7 membered ring), or iodosobenzene.According to the present invention, perfluoro-olefins can be converted to corresponding perfluoroepoxides cheaply and in high yields.

Abstract: The present invention provides ice nucleating-active materials which are free from problems like corrosiveness against a device owing to the materials used and harmfulness of the materials themselves; and have a function of elevating freezing temperature of water which is effective for releasing an over-cooling state of it, and generates a method for an ice bank system exhibiting a large energy-saving effect. This invention relates to ice nucleating-active materials containing trioctahedral smectites capable of being dispersive in water as effective components, and a method for an ice bank system comprising adding the trioctahedral smectites into a liquid in the ice bank system at a concentration of at least 30 ppm and freezing it by using a freezer.

Abstract: A novel method is proposed for the preparation of a calcium silicate powder particularly useful as a filter aid in the filtration of an acidic aqueous liquid by virtue of the extremely high acid resistance of the calcium silicate powder. The inventive method comprises a hydrothermal reaction of a blend of a silica-containing material and calcium oxide or hydroxide in a specified molar ratio under specified reaction conditions to form calcium silicate, which is then subjected to a heat treatment at 800.degree.-1200.degree. C. for 0.5-2 hours. An improvement can be obtained in the clarity of the filtrate obtained by the filtration using the calcium silicate powder prepared by the inventive method as a filter aid when the hydrothermal reaction for the preparation thereof is conducted in an aqueous solution of potassium hydroxide in a specified concentration.

Abstract: Disclosed is a novel compound having activity as an ionophore for ion transport, which is a monoester or monoamide of 1,3,5-trimethyl-1,3,5-cyclohexane tricarboxylic acid, i.e. Kemp's triacid or the stereoisomer thereof, the group R in the ester group --COOR or in the amide group --CONHR being an aralkyl group or aryloxyalkyl group having 7 to 20 carbon atoms. The monoester and monoamide derivatives can be synthesized from anhydride of Kemp's triacid by subjecting the anhydride to a ring-opening esterification or amidation reaction with an alcohol or amine. On the other hand, both of the stereoisomers can be obtained by the dehydrohalogenation reaction of 1,3,5-trimethyl-1,3,5-cyclohexane tricarboxylic acid anhydride acid halide with an alcohol or amine followed by the ring-opening hydrolysis reaction on the anhydride group.

Abstract: A photocatalyst sheet capable of purifying the living environment by decomposing and removing malodorous substances and environment-polluting substances in the air, preventing development of bacterium, fungi, and protecting contamination, and a method for production thereof which comprises coating a solution of a titania sol on the surface of a sheet of organic substance such as plastic, and heating it under pressure to deposit the titanium powder on the surface of the sheet.

Abstract: When a saturated aqueous solution of a bolaform glycolipid represented by the general formulaG--NH--CO--(CH.sub.2).sub.n --CO--NH--G,in which G is a residue derived from a D- or L-glucopyranose by excepting the reduced-terminal hydroxyl group and the subscript n is 10, 12 or 14, at a high temperature, e.g., 90 .degree. C. or higher, is cooled at a controlled rate of 0.5 .degree. C./minute or lower, crystallite growth of the precipitates proceeds to form an ultrafine fibrous assembly of up to several hundreds .mu.m length having a twisted fibrous morphology of right- or left-hand screw. The twisted fibrous assembly thus obtained has usefulness as a functional material in the field of fine chemicals and in the fields of electronic and information technologies.

Abstract: Disclosed is a novel .beta.-lactam compound, a 7-substituted-2-oxa-7-azabicyclo?3.2.0!heptan-6-one represented by the general formula ##STR1## in which R is an alkyl, cycloalkyl, aryl, halogen-substituted aryl or alkaryl group, having usefulness as an intermediate for the synthesis of various biologically active compounds. The compound can be prepared by the reaction of an isocyanate compound RNCO, R being the same as above, and 2,3-dihydrofuran, preferably, under pressurization up to 2000 atmospheres or higher.

Abstract: Disclosed is a method for the preparation of a fiber-reinforced silicon carbide-based composite ceramic body having outstandingly high mechanical strengths even without using any sintering aids or without undertaking the hot-press sintering method. The method comprises impregnating carbon fibers or silicon carbide fibers with a slurry containing an elementary silicon powder, an organic resin, e.g., phenolic resins, and an organosilicon polymer, e.g., polysilastyrenes, according to a specified formulation and shaping the impregnated fibers into a green body which is subjected to a calcination treatment at 1300.degree.-1500.degree. C. in an inert atmosphere under normal pressure.

Abstract: A novel and simple method is proposed for the synthetic preparation of an N,N-disubstituted .beta.-ketothioamide compound represented by the general formulaR.sup.1 R.sup.2 N--CS--CH.sub.2 --CO--R.sup.3,in which R.sup.1 and R.sup.2 are each a monovalent hydrocarbon group or each a divalent hydrocarbon group jointly forming a cyclic structure together with the nitrogen atom and R.sup.3 is a hydrogen atom, a monovalent hydrocarbon group or a divalent hydrocarbon group forming a cyclic structure jointly with R.sup.1, R.sup.1 being a divalent hydrocarbon group and R.sup.2 being a monovalent hydrocarbon group. The method comprises:(a) mixing an N,N-disubstituted amide compound represented by the general formulaR.sup.1 R.sup.2 N--CO--R.sup.3,and a bis(trialkylsilyl)thioketene compound represented by the general formula(R.sub.3 Si).sub.2 C.dbd.C.dbd.

Abstract: Proposed is a grain boundary-free crystalline body of a perovskite structure having a chemical composition of the formula Pr.sub.1-x M.sub.x MnO.sub.3, in which M is calcium or strontium and the subscript x is a number of 0.3 to 0.5, which exhibits a magnetoresistance behavior with a phase transition between an insulator phase and a ferromagnetic metallic phase accompanied by the phenomenon of hysteresis. This grain boundary-free crystalline body can be obtained by subjecting a sintered body of a powder blend consisting of the oxides of praseodymium, manganese and calcium or strontium to a crystal growing treatment by the floating zone-melting method in an atmosphere of oxygen.

Abstract: The extrusion moldability of particle-reinforced composites under fresh cition relative to the extruding pressure and extruding velocity can be pre-estimated from the cohesion and the coefficient of internal friction of the composite which can be calculated from the relationship of, when a frame divided into the upper and lower halves are filled with the composite and the upper and lower halves of the frame are displaced relative to each other in the horizontal direction under a pressure on the composite filling the frame, the shear stress of the composite against slip deformation.