Abstract: The novel transition metal compound of the invention is represented by the following formula (I): ##STR1## wherein M is a transition metal; R.sup.1 is a hydrocarbon group of 2 to 6 carbon atoms, R.sup.2 is an aryl group of 6 to 16 carbon atoms; X.sup.1 and X.sup.2 are each a halogen atom or the like; and Y is a divalent hydrocarbon group, a divalent silicon-containing group or the like. An olefin polymerization catalyst component of the present invention comprises the aforementioned transition metal compound.

Abstract: A process for polymerizing propylene utilizes a metallocene catalyst component of the formula (I) ##STR1## wherein M is a transition metal, R.sup.1 is a C.sub.2-6 hydrocarbon, R.sup.2 is a C.sub.6-16 aryl group, X.sup.1 and X.sup.2 are each a halogen atom and Y is a divalent hydrocarbon or a divalent silicon-containing group. Propylene polymers produced thereby have such properties that the triad tacticity of propylene units is high, the proportion of inversely inserted units based on the 2,1-insertion of propylene monomer is in a specific range and the intrinsic viscosity (.eta.), as measured in decahydronaphthalene at 135.degree. C., is in a specific range.

Abstract: The novel transition metal compound of the invention is represented by the following formula (I): ##STR1## wherein M is a transition metal; R.sup.1 is a hydrocarbon group of 2 to 6 carbon atoms, R.sup.2 is an aryl group of 6 to 16 carbon atoms; X.sup.1 and X.sup.2 are each a halogen atom or the like; and Y is a divalent hydrocarbon group, a divalent silicon-containing group or the like. An olefin polymerization catalyst component of the present invention comprises the aforementioned transition metal compound. An olefin polymerization catalyst of the present invention comprises the aforementioned olefin polymerization catalyst component. The propylene homopolymer, the propylene copolymer and the propylene elastomer according to the present invention have such properties that the triad tacticity of propylene units chain is high, a proportion of the inversely units based on the 2,1-insertion of propylene monomer is in the specific range, and the intrinsic viscosity [.eta.

Abstract: The novel transition metal catalyst of the invention is represented by the following formula (I): ##STR1## wherein M is a zirconium or hafnium; R.sup.1 is a hydrocarbon group of 2 to 6 carbon atoms, R.sup.2 is an aryl group of 6 to 16 carbon atoms; X.sup.1 and X.sup.2 are each a halogen atom; and Y is a divalent hydrocarbon group, a divalent silicon-containing group.

Abstract: A silicon nitride film 2 is formed on a GaAs substrate 1 and patterned to selectively expose the GaAS substrate surface in uniformly distributed areas having a width of not greater than 1 .mu.m. A non-doped GaAs buffer layer is grown on the GaAs substrate to completely cover the silicon nitride film. Then, a semiconductor multilayer structure including a non-doped GaAs layer is formed on the non-doped GaAs buffer layer. When a semiconductor integrated circuit device is manufactured using this semiconductor substrate, side gate effect can be effectively reduced due to the existence of the silicon nitride pattern and the buffer layer.

Abstract: Disclosed is a novel transition metal compound represented by the following formula: ##STR1## wherein M is a transition metal, X is halogen or the like, R.sup.1 is a hydrocarbon group or the like, R.sup.2 is an aryl group substituted with a halogenated hydrocarbon group, and Y is a divalent silicon-containing group or the like.Also disclosed are an olefin polymerization catalyst component comprising the transition metal compound, an olefin polymerization catalyst comprising the olefin polymerization catalyst component, and a process for olefin polymerization using the olefin polymerization catalyst.An olefin polymerization catalyst component having high polymerization activity can be formed from the transition metal compound. By the use of the olefin polymerization catalyst or the process for olefin polymerization, polyolefins having a high melting point and a high molecular weight can be prepared with high polymerization activity.

Abstract: The present invention relates to molecr beam epitaxy, in particular, to a gas source molecular beam epitaxy apparatus using compound gases as sources of semiconductor component elements, and also relates to a method for growing semiconductor crystal using this apparatus. It is an object of the present invention to prevent an epitaxial layer from being contaminated with organic compounds produced by decomposition of source gases. It is another object to grow a high purity semiconductor crystal at a growth rate high enough for practical applications. To achieve the above objects, in a growth apparatus in accordance with the present invention, the ambient gas pressure is maintained at the order of 10.sup.-5 -10.sup.-3 Torr during a growing process.

Abstract: The catalyst for olefin polymerization of the present invention contains R.sub.k.sup.1 R.sub.l.sup.2 R.sub.m.sup.3 M(SO.sub.3 R.sup.4) (M=Zr, Ti or Hf; R.sup.1-3 =a group having a cyclopentadienyl skeleton) as a catalyst component of a transition metal compound. According to the catalyst of the invention, an olefin polymer having excellent particle properties can be prepared with high polymerization activities, and further a copolymer having a narrow composition distribution can be prepared when two or more monomers are copolymerized. Of the above-mentioned transition metal compounds, a compound represented by the following formula is a novel compound unknown so far and shows excellent catalytic properties. ##STR1## (Cp=a group having a cyclopentadienyl skeleton, X=SO.sub.3 R, a halogen atom, R, OR, NR.sub.n, S(O).sub.q R, SiR.sub.3 or P (O).sub.q R.sub.

Abstract: The catalyst for olefin polymerization of the present invention contains R.sup.1.sub.k R.sup.2.sub.l R.sup.3.sub.m M(SO.sub.3 R.sup.4) (M=Zr, Ti or Hf; R.sup.1-3 =a group having a cyclopentadienyl skeleton) as a catalyst component of a transition metal compound. According to the catalyst of the invention, an olefin polymer having excellent particle properties can be prepared with high polymerization activities, and further a copolymer having a narrow composition distribution can be prepared when two or more monomers are copolymerized. Of the above-mentioned transition metal compounds, a compound represented by the following formula is a novel compound unknown so far and shows excellent catalytic properties. ##STR1## (Cp=a group having a cyclopentadienyl skeleton, X=SO.sub.3 R, a halogen atom, R, OR, NR.sub.n, S(O).sub.q R, SiR.sub.3 or P(O).sub.q R.sub.

Abstract: A silicon nitride film 2 is formed on a GaAs substrate 1 and patterned to selectively expose the GaAS substrate surface in uniformly distributed areas having a width of not greater than 1 .mu.m. A non-doped GaAs buffer layer is grown on the GaAs substrate to completely cover the silicon nitride film. Then, a semiconductor multilayer structure including a non-doped GaAs layer is formed on the non-doped GaAs buffer layer. When a semiconductor integrated circuit device is manufactured using this semiconductor substrate, side gate effect can be effectively reduced due to the existence of the silicon nitride pattern and the buffer layer.

Abstract: A process for the thermal-etching treatment of a GaAs substrate subjected to molecular beam epitaxy, which includes: heating the GaAs substrate above a temperature of 750.degree. C., at which temperature both Ga and As are eliminated from the GaAs substrate, while irradiating the GaAs substrate with an As molecular beam. After the heating and irradiating is complete contamination adhering to the GaAs substrate by eliminating a part of the underlying GaAs. The process can be performed by an apparatus which includes a prechamber and a growth chamber for growing an epitaxial layer.

Abstract: A boehmite having an orthorhombic crystal form in which the ratio of the maximum length in the direction of the a-axis of the crystal to the distance between the opposing crystal faces perpendicular to the c-axis of said crystal is at least 10, said maximum length in the direction of the a-axis of the crystal is at least 2500 .ANG. and said distance between the opposing faces perpendicular to the c-axis of said crystal is 250-900 .ANG..

Abstract: A boehmite having a crystal form wherein the ratio of the maximum length in the direction of the a-axis to the distance between the opposing crystal faces perpendicular to the c-axis is at least 10.

Abstract: A process for producing a boehmite shaped product comprises slurrying a mixture of a gibbsite powder and at least one powder selected from the group consisting of powders of pseudo-boehmite, amorphous aluminum hydroxide, alumina cement and .rho.-alumina, molding the slurry thereby obtained and subjecting the molded product to hydrothermal treatment.

Abstract: A process for preparing a calcium silicate shaped product comprises heat-reacting a calcareous source and a siliceous source dispersed in water to obtain an aqueous slurry containing a calcium silicate hydrate having a molar ratio of CaO/SiO.sub.2 being more than 1, adding a siliceous source to the aqueous slurry to bring the molar ratio of CaO/SiO.sub.2 to a level of from 0.85 to 1, and pressfilter-molding the aqueous slurry thereby obtained, followed by steam-curing and drying.

Abstract: A calcium silicate shaped product is produced by forming an aqueous slurry of calcium silicate hydrate obtained by reacting a calcareous source with a siliceous source dispersed in water under heating; molding said aqueous slurry and heat-treating said molded product under the condition providing the equations (I) and (II);100.ltoreq..theta..multidot.T (I)50.ltoreq..theta..ltoreq.300 (II)wherein .theta. represents a temperature of the inner part of the molded product (.degree.C.) and T represents a time (hour) and providing a percent water loss of the treated molded product of less than 25 wt. %, before drying or steam-curing and drying the molded product.

Abstract: An aqueous slurry of calcium silicate hydrate which is formed by heating a siliceous source and a calcareous source in water to react them and which has the specific property is shaped with a press filter molding and cured by a steam curing under steam pressure to cause a transformation of the calcium silicate hydrate whereby a calcium silicate shaped product having low bulk density and high mechanical strength is obtained. The calcium silicate shaped product is suitable as a lagging product or a heat insulator.

Abstract: Nitrogen oxides in exhaust gases are catalytically reduced in the presence of oxygen and ammonia at 200.degree. to 600.degree. C. over a catalyst of at least one catalyst component selected from the group consisting of compounds of metals of Groups 1B, 5A, 6A, 7A and 8 of the periodic table, and lanthanides and tin which is supported on a specific carrier comprising a main component of calcium silicate.

Abstract: An aqueous slurry of calcium silicate hydrate which is formed by heating a siliceous source and a calcareous source in water to react them and which has the specific property is shaped with a press filter molding and cured by a steam curing under steam pressure to cause a transformation of the calcium silicate hydrate whereby a calcium silicate shaped product having low bulk density and high mechanical strength is obtained. The calcium silicate shaped product is suitable as a lagging product or a heat insulator.