Abstract: A method of fabricating a semiconductor crystal mesa stripe whose waist section is narrower than the upper plane of said mesa stripe. The method comprises the steps of forming a first striped mask on the semiconductor crystal wafer in order to fabricate a prescribed mesa stripe, linearly arranging a plurality of second striped masks, narrower than said first striped mask by the prescribed waist width of the main mesa stripe, on the semiconductor wafer plane at prescribed intervals and in parallel with said first striped mask in order to fabricate monitor mesa stripes; and of subjecting said semiconductor wafer plane to mesa etching.

Abstract: An improved method for deresination of wood chips or pulp is provided. The method comprises contacting the chips or pulp with an ethoxylated alkyl phenol deresinating composition during processing to reduce the level of natural resins present therein. The improvement comprises substituting a sufonated fatty acid for part of the ethoxylated alkyl phenol while maintaining substantially the same level of deresination.

Abstract: Vapor from liquid ethylene dibromide (EDB) functions in a manner superior anhydrous HCl for in situ gas phase etching of InP substrates in Metalorganic Vapor Phased Epitaxy (MOVPE). The etch rate and surface morphology behaviors have been determined for conditions useful as a substrate cleaning step prior to growth of InP and InGaAs epilayers. The thermally activated decomposition and etching are analogous to group III-V semiconductor growth processes; the behavior in different carrier gas mixtures demonstrates dependence on gas phase reactions in the heated vapor above the substrate.

Abstract: A chemical-mechanical (chem-mech) method for removing SiO.sub.2 protuberances at the surface of a silicon chip, such protuberances including "bird's heads". A thin etch stop layer of Si.sub.3 N.sub.4 is deposited onto the wafer surface, which is then chem-mech polished with a SiO.sub.2 water based slurry. The Si.sub.3 N.sub.4 acts as a polishing or etch stop barrier layer only on the planar portions of the wafer surface. The portions of the Si.sub.3 N.sub.4 layer located on the top and at the sidewalls of the "bird's heads" and the underlying SiO.sub.2 protuberances are removed to provide a substantially planar integrated structure.

Abstract: In an apparatus for synthesizing polynucleotide including a plurality of reactors, bottles charged with reagents and solvents, and change valve means for switching passages between respective bottles and the reactors, the improvement comprises mode selector means between a pressure source and the reactors for switching liquid supply or discharge operation and distributor means for closing or opening passages connected with the reactors to selectively operate the reactors.

Abstract: Process and apparatus are disclosed for increasing argon recovery in conjunction with cryogenic distillation of air to high purity oxygen. The increased argon recovery is obtained by incorporating one or more latent heat exchangers in the flowsheet at strategic disclosed locations and between specific fluids. The invention is particularly advantageous in conjunction with LOXBOIL flowsheets, which otherwise lose O.sub.2 recovery when argon recovery is increased.

Abstract: A cold trap for the removal of a component from a gas mixture includes a cooling coil, made up of cooling sections of highly thermally conductive material and intermediate sections of low thermal conductivity, and a heating coil arranged for controlling the inlet temperature to equal the saturation temperature of that component in the gas mixture, its outlet temperature to equal the saturation temperature at a desired residual concentration of the component in the mixture and the temperature of cooling surfaces between the inlet and the outlet at a temperature which substantially falls linearly from the inlet temperature to the outlet temperature. The cooling surfaces extend generally perpendicular to the principal gas flow direction and the residence time of the gas is comparatively large so that the gas is practically at the temperature of the cooling surfaces at all times and nucleation in the gas spaces which might lead to obstruction of the flow passages is precluded.

Abstract: A gas can be separated by condensation from a gaseous mixture by exposing the mixture to reduced temperature in a chamber having an outlet. The outlet contains a restrictive structure, such as a sintered glass filter disc, on which a thin film of the condensed liquid forms. Liquid is drawn off through the restrictive structure while the film is replenished so that a barrier layer of the liquid which seals the outlet is continuously maintained. The gas may be ozone made from electrical treatment of oxygen and the resulting liquid ozone may be used for water purification.

Abstract: A system and process for preparation of dialysis concentrate solution from dry chemicals and water. The source of hemodialysis chemicals for a batch is a drum selectively filled with dry chemicals such that an inner core region therewithin is loaded with chemicals which slurry and dissolve the least readily. The required amount of water is metered into a mix tank. Water is pumped from the tank into a spray head fitted over the selectively filled drum. Water is injected onto the chemicals within the inner core region by the use of a nozzle having a narrow spray angle. The chemicals within the inner core region are preferentially dissolved or slurried before the other chemicals within the drum. The slurried and dissolved chemicals are removed from the drum by a suction wand and are entirely solubilized in the tank. Cycling of fluid continues from the drum to the tank and vice versa until all of the chemicals in the drum have been removed. Circulation of the fluid is continued until a uniform solution results.

Abstract: The present invention involves a process for recovering hydrogen from a feed gas mixture comprising hydrogen and at least one other component. The feed gas mixture is initially separated in a membrane separation unit to produce a hydrogen-rich stream and a hydrogen-lean stream. The hydrogen-lean stream is subsequently treated in a cryogenic separation unit to remove a portion of the non-hydrogen components and produce a hydrogen-enriched stream. The hydrogen-enriched stream from the cryogenic separation unit is recycled and combined with the feed gas mixture to the membrane separation unit.

Abstract: In order to avoid marking by the supporting surfaces in an endless belt for paper machines or the like with a number of helices consisting of opposing winding legs and headcurves joining these flanks together and into whose intermediary spaces the headcurves of the neighboring helix are forced to a degree that there develops between the two helices a range of overlapping into which a rod is inserted and in order to create the possibility for regulating the flow of air through the wire belt, at least the paper web-supporting winding legs of the helices are glued with a layer of fiber segments. Additionally, in such an endless belt permeability may be controlled by providing fiber segments on the winding legs and/or on the side areas adjacent the loop flanks.

Abstract: A paper machine where the press section features exclusively double felt roll presses (13-16; 23-26) through which proceeds the paper web (10) to be dehydrated between two felt belts (15,16; 25, 26). The paper web (10) is constantly supported by a backing belt (34) at least in the first drying group of the drying section. The transition of the paper web (10) from one roll press to the next and from the press section to the drying occurs without an open draw. The first drying cylinder (31) is located outside the backing belt loop (34), with the paper web (10) proceeding across the upper cyliner area of this drying cylinder (31). The entrance point of a rope carrier (45,46) (serving to thread the paper web into the drying section) is located behind the leaving point of the paper web (10) from the first drying cylinder (31).

Abstract: Apparatus for removing volatile components from a liquid includes three distinct sections of a confined passageway for the liquid. The first section is for heating the liquid to a predetermined temperature at a preselected pressure such that vaporization of the volatile components is prevented. The second section of the confined passageway is a restrictive orifice forming flow path. The third section is a volatile component evaporation section. The volatile component evaporation section and the restrictive orifice forming flow path are dimensioned relative to one another and in respect of the preselected pressure and temperature of the liquid product such that the volatile components of the liquid substantially instantaneously vaporize in a flashing action as the liquid passes from the restrictive orifice forming flow path to the volatile component evaporization section.

Abstract: The hydrotreatment of hydrocarbons in the liquid phase is effected in a column containing a catalyst bed supported by a grid, wherethrough passes an ascending stream of the charge admixed with hydrogen which expands the catalyst bed, the perforations of the grid being small enough to prevent passage of the catalyst particles but large enough to permit passage of the hydrogen-charge mixture, the reaction effluent being withdrawn from the top of the column. The reactor column is provided with means between the hydrogen-charge mixture introducing means and the catalyst bed supporting grid for mixing and dispersing the combined liquid-gas charge.

Abstract: The instant invention is directed to a process for stripping of a residual component from a liquid having a viscosity of from 300 to 10,000 poises in which the liquid flows in the form of a ring flow supported by a gas stream flowing in the core, through a tube into a separator vessel, the tube having a continuous coil shape and a conduit diameter to helix diameter of from 0.1:1 to 0.04:1, the improvement comprising adding to the gas stream from 10 to 90%, by weight, of externally generated steam and/or an inert gas at an adjusted pressure of from 50 m bars to 1 bar in the separator vessel for a gas and/or steam velocity in the tube of from 100 m/sec to the speed of sound. The added gas and/or steam generates thorough transverse mixing in the liquid ring flow.

Abstract: The present invention is generally directed to an improved process and apparatus for the production of gaseous products such as ammonia by catalytic, exothermic gaseous reactions and is specifically directed to an improved process which utilizes a gas-phase catalytic reaction of nitrogen and hydrogen for the synthesis of ammonia. This improved process for the production of ammonia utilizes an ammonia converter apparatus designed to comprise at least two catalyst stages and a reheat exchanger so arranged as to provide indirect heat exchange of the gaseous effluent from the last reactor catalyst stage with the effluent from at least one other reactor catalyst stage having a higher temperature level in order to reheat the effluent from the last reactor catalyst stage prior to exiting the reactor vessel, thereby facilitating higher level heat recovery from the reactor effluent.

Abstract: A method of inhibiting zinc corrosion in aqueous systems comprising adding an effective amount of a bis(aminotriazole) or a bis(mercaptotriazole), whose bridge may be substituted by a C.sub.0-10 -alkyl.

Abstract: A process for the separation of water from a water-containing mixture of azeotrope, with an extractant which removes water from the mixture or azeotrope, recovery of the non aqueous portion of the mixture or azeotrope as a product, and regeneration of the extractant for reuse by the removal of water therefrom. A feature thereof is that residual water can be removed from the extractant, and the extractant regenerated for reuse by contacting the heated extractant with a portion of the same product from which the water has been removed; or, the extractant can be regenerated in the process by contact with an inert gas which has been dried in the process. The water-containing mixture or azeotrope is preferably contacted with a portion of the vaporous product to recover the heat of condensation for use in the process.

Abstract: A process for controlling a distillation column in which a feedstock is distilled for separation into a product from the top of the column having a first predetermined content of an intended component with a high boiling point and a product from the bottom of the column having a second predetermined content of an intended component with a low boiling point. The process includes the steps of computing a desired value of the flow rate of the product from the bottom of the column in accordance with a material balance and controlling the flow rate of the bottom product in accordance with a corrected desired value which is derived from one of deviations between the actual and desired compositions of the top or bottom products or limit values depending upon the magnitude and direction of the deviations. Reflux of part of the top product to the column is also controlled in accordance with the direction of the deviations and their magnitudes or limiting values.

Abstract: An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.