Abstract: An optoelectronic device for outfeed and infeed of radiation into and out of a waveguide having the waveguide disposed on a substrate and provided with a mirror for reflecting the light through the substrate. The device includes at least a plano-convex lens being integrated on a surface of the substrate lying opposite the waveguide. In one embodiment, a second substrate is secured on the first substrate and one of the substrates has a recess for receiving the lens and the second substrate can have a recess aligned with the lens for receiving an end of an optical fiber.

Abstract: The process of preparing silicon nitride is improved by reacting silicon-oxygen compounds and a carbon-containing material in an ammonia or ammonia/nitrogen atmosphere at 1300.degree. to 1600.degree. C.

Abstract: A power distribution system for supplying power to a plurality of point-to-load power supplies includes a plurality of bulk power supplies, each having a separate respective power distribution bus coupled at the output thereof. Each power distribution bus is coupled to each point-of-load power supply through an OR gate such that if one or more of the bulk power supplies fails, or if a fault occurs on one or more of the power distribution buses, then the point-of-load power supplies are unaffected because they continue to receive power from the other bulk power supplies via the respective OR gates. Furthermore, if a power distribution bus becomes short-circuited to ground, the current therein is limited electronically by the respective bulk power supply. Hence, the power distribution buses are protected against overcurrent without the need for a multitude of dc circuit breakers.

Abstract: Silicon nitride powder having a total oxygen content of less than 1.8% by weight and an isoelectric point in 0.001M aqueous KNO.sub.3 solution of below pH 4 is prepared by calcining Si.sub.3 N.sub.4 powder having an oxygen content of 0.4% by weight or less in an oxygen containing atmosphere at temperatures between 700.degree. and 1200.degree. C. for 15 to 90 minutes or by grinding such as Si.sub.3 N.sub.4 powder in water, lower alcohol or a water/alcohol mixture for 15 to 120 minutes.

Abstract: The present invention relates to an SiC powder suitable for the production of SiC sintered ceramics with compounds applied to its surface, these compounds being boron nitride and carbon; processes for production of the SiC powders; and the use of these powders to produce SiC sintered mouldings.

Abstract: Si.sub.3 N.sub.4 powders having a total oxygen content of less than 1.8% by weight with the proportion of surface oxygen content of more than 65% of the total oxygen content, and having a fluorine content of less than 35 ppm are prepared by annealing Si.sub.3 N.sub.4 powders having a total oxygen content of less than or equal to 0.4% by weight in an oxygen-containing atmosphere at temperatures of 700.degree. C. to 1200.degree. C. for 15 to 90 minutes or by grinding Si.sub.3 N.sub.4 powders having a total oxygen content of less than or equal to 0.4% by weight in water, alcohol or aqueous alcohol 15 to 120 minutes.

Abstract: Si.sub.3 N.sub.4 powder wherein the total oxygen content of the powder is 0.4% by weight or less is produced by preparing an amorphous Si.sub.3 N.sub.4 intermediate by reacting a Si-containing compound with an N-containing compound and the intermediate is then crystallized wherein "P", multiplication product of(i) the specific surface of the amorphous intermediate (BET in m.sup.2 /g),(ii) the moisture content C.sub.H.sbsb.2.sub.O (in volume ppm) of the atmosphere during handling and(iii) the time t in hours required for handling the amorphous intermediate,is kept smaller than the limit value product P.sub.G of 1000 in accordance with the following equation:"P"=BET (m.sup.2 /g).times.C.sub.H.sbsb.2.sub.O (vol ppm).times.t(h)<P.sub.G.

Abstract: Sinterable Si.sub.3 N.sub.4 powder containing Si.sub.3 N.sub.4 particles and sintering additives wherein Si.sub.3 N.sub.4 particles have an average particle size of less than 1 .mu.m, contain no particle having a diameter greater than 100 .mu.m, have a total content of metallic impurities less than 1000 ppm and an iron content of less than 200 ppm, and wherein the sintering additives are uniformly distributed throughout the powder is prepared by co-grinding pulverulent sintering additive and Si.sub.3 N.sub.4 containing less than 1000 ppm metallic impurities in a spiral jet mill.

Abstract: Carbides, nitrides or carbonitrides of elements from the main groups III and IV and sub-groups III, IV, V and VI of the periodic system of elements are prepared by(i) reacting compounds of the formula MX.sub.m or R.sub.n MX.sub.m-n with a reactive hydrocarbon-containing compound or a mixture of compounds which is polymerizable and which contains a reactive compound with one C--OH-group in whichM is an element of the main group III or IV or sub-group of III, IV, V or VI of the periodic system of elements,X is a halogen,R is hydrogen or alkyl or aryl,m is an integer corresponding to the valency stage of M,n is an integer from 1 to one less than the velency stage of M, and(ii) thermally decomposing the resulting product from (i) to the corresponding carbide or to the corresponding nitrides or carbonitrides with further nitridation.

Abstract: A synchronous rectifier circuit employs therein a pair of synchronously-operated switches, each switch being coupled between a separate respective input terminal and an output terminal of the circuit. One of the synchronously-operated switches is gated ON when a voltage applied across the synchronous rectifier circuit input terminals is of one polarity, and is gated OFF when current therein becomes substantially zero. The second switch is gated ON when a voltage applied across the input terminals is of the opposite polarity, and is gated OFF when current therein becomes substantially zero.

Abstract: Sinterable Si.sub.3 N.sub.4 powder having an average particle size of less than 1 .mu.m, wherein no individual particle has a diameter greater than 100 .mu.m, the total content of metallic impurities of the powder is less than 1000 ppm and the iron content is less than 200 ppm is produced by grinding agglomerated Si.sub.3 N.sub.4 in a spiral jet mill.

Abstract: An improved process for preparation of silicon nitride powder having a low carbon content comprises treating silicon nitride powder with an atmosphere containing chlorine gas at temperatures from 600.degree. to 1050.degree. C. and then with an atmosphere containing gaseous oxygen.

Abstract: A process for the production of an anisometric yellow-brown zinc ferrite pigment comprising homogeneously mixing zinc oxide having a specific BET surface of more than 2 m.sup.2 /g with needle-shaped .alpha.-FeOOH obtained from an iron salt solution by mixing with alkali and subsequently oxidizing in a nucleation and pigment growth stage, the FeOOH having a specific BET surface of about 15 to 25 m.sup.2 /g, an average needle width of about 0.025 to 0.125 .mu.m and an average needle length of about 0.2 to 0.6 .mu.m, annealing the mixture at a temperature of about 700.degree. to 1000.degree. C., cooling and grinding.

Abstract: In the production of an .alpha.-iron oxide pigment by the hydrothermal treatment of a trivalent iron-containing solution or suspension, the improvement which comprises adding to the solution or suspension prior to the hydrothermal treatment active .alpha.-iron oxide seeds with lamellar or disc-like crystal form and a specific surface of at least 10 m.sup.2 /g, whereby the resulting pigment is lamellar with an Fe.sub.2 O.sub.3 content of at least 88%, an average particle diameter of from 0.5 to 20 .mu.m, an average ratio of diameter to thickness of from 20 to 100, and an almost normally distributed particle size distribution, the relative standard deviation of which, based on the average value of the normal distribution, is less than 0.3. The product has superior coloring properties and is used as a precursor compound for the production of lamellar magnetic pigments with superior magnetic properties.

Abstract: Synthetic, hexagonal, lamellar iron oxide particles, suitable as corrosion-inhibiting or decorative colored pigments, containing about 0.1 to 12% by weight of at least one oxide of an element of the IVth, Vth or VIth Main and Secondary Groups and of the IInd Secondary Group of the Periodic System of Elements.

Abstract: A process for the catalytic skeleton isomerization of n-alkenes to isoalkenes comprises contacting the n-alkene with a fluorinated aluminum oxide as the catalyst at temperatures of 250.degree.-550.degree. C., in the presence of 0.5-150% by weight of water, based on the weight of the alkene employed and replenishing the fluorine discharged from the catalyst in metered amounts, continuously or discontinuously, using, e.g., a volatile fluorine compound. The catalyst, partially deactivated by coking, is regenerated by burning it off with an oxygen-containing gas in the presence of steam.

Abstract: Ethylenically unsaturated C.sub.4 -n-hydrocarbons are oxidized to maleic anhydride by passing a stream of oxygen-containing gas at high temperature over a catalyst of the formulaW.sub.a Mo.sub.b Sb.sub.c Y.sub.d X.sub.e O.sub.xwherein Y=P, Si; X=V, Bi, Te, alkali metal; a and b each =1-12; c=2-20; d=0.2-2; e=0-10; and x is the number of oxygen atoms required to satisfy the remaining valences of the other elements, prepared by reacting an Sb compound and optionally also a V, Bi, Te and/or alkali metal compound, with a solution of a heteropoly acid of Mo and W, drying and tempering the resultant blue complex.

Abstract: Ethylenically unsaturated C.sub.4 -n-hydrocarbons are oxidized to maleic anhydride by passing a stream of oxygen-containing gas at high temperature over a catalyst of the formulaW.sub.a Mo.sub.b Sb.sub.c Y.sub.d X.sub.e O.sub.xwherein Y=P, Si; X=V, Bi, Te, alkali metal; a and b each=1-12; c=2-20; d=0.2-2; e=0-10; and x is the number of oxygen atoms required to satisfy the remaining valences of the other elements, prepared by reacting an Sb compound and optionally also a V, Bi, Te and/or alkali metal compound, with a solution of a heteropoly acid of Mo and W, drying and tempering the resultant blue complex.

Abstract: Isobutyraldehyde is produced by the oxo process and converted to acetone in the gas phase by oxidative decarbonylation on a zinc oxide supported copper oxide catalyst. The conversion is improved by adding about 2.5 to 25 percent by weight graphite to the catalyst, based on the total weight of catalyst.

Abstract: A semi-continuous process for manufacturing aliphatic or aromatic amino compounds by reduction of the corresponding nitro compounds in an acid medium with iron which is etched with acids or salts is provided.