Patents Assigned to Midwest Research Institute
  • Patent number: 5639520
    Abstract: A process for producing a silicon dioxide film on a surface of a silicon substrate. The process comprises illuminating a silicon substrate in a substantially pure oxygen atmosphere with a broad spectrum of visible and infrared light at an optical power density of from about 3 watts/cm.sup.2 to about 6 watts/cm.sup.2 for a time period sufficient to produce a silicon dioxide film on the surface of the silicon substrate. An optimum optical power density is about 4 watts/cm.sup.2 for growth of a 100.ANG.-300.ANG. film at a resultant temperature of about 400.degree. C. Deep level transient spectroscopy analysis detects no measurable impurities introduced into the silicon substrate during silicon oxide production and shows the interface state density at the SiO.sub.2 /Si interface to be very low.
    Type: Grant
    Filed: January 26, 1996
    Date of Patent: June 17, 1997
    Assignee: Midwest Research Institute
    Inventor: Bhushan L. Sopori
  • Patent number: 5627081
    Abstract: The instant invention teaches a novel method for fabricating silicon solar cells utilizing concentrated solar radiation. The solar radiation is concentrated by use of a solar furnace which is used to form a front surface junction and back-surface field in one processing step. The present invention also provides a method of making multicrystallline silicon from amorphous silicon. The invention also teaches a method of texturing the surface of a wafer by forming a porous silicon layer on the surface of a silicon substrate and a method of gettering impurities. Also contemplated by the invention are methods of surface passivation, forming novel solar cell structures, and hydrogen passivation.
    Type: Grant
    Filed: November 29, 1994
    Date of Patent: May 6, 1997
    Assignee: Midwest Research Institute
    Inventors: Y. Simon Tsuo, Marc D. Landry, John R. Pitts
  • Patent number: 5599229
    Abstract: By enhancing the natural instabilities in the boundary layer and in the free shear layer of a wall jet, the boundary is minimized thereby increasing the transport of heat and mass. Enhancing the natural instabilities is accomplished by pulsing the flow of air that creates the wall jet. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct.
    Type: Grant
    Filed: May 8, 1995
    Date of Patent: February 4, 1997
    Assignee: Midwest Research Institute
    Inventors: Scott D. Claunch, Robert B. Farrington
  • Patent number: 5591690
    Abstract: The present invention relates to a gettering material that may be used as a filtration medium to remove pollutants from the environment. The gettering material comprises a high surface area material having a metal surface that chemically bonds n-alkanethiols in an organized manner thereby forming a molecular monolayer over the metal surface. The n-alkanethiols have a free functional group that interacts with the environment thereby binding specific pollutants that may be present. The gettering material may be exposed to streams of air in heating, ventilation, and air conditioning systems or streams of water to remove specific pollutants from either medium.
    Type: Grant
    Filed: June 29, 1994
    Date of Patent: January 7, 1997
    Assignee: Midwest Research Institute
    Inventors: David E. King, Gregory C. Herdt, Alvin W. Czanderna
  • Patent number: 5588995
    Abstract: A system for monitoring the growth of crystalline films on stationary or rotating substrates includes a combination of some or all of the elements including a photodiode sensor for detecting the intensity of incoming light and converting it to a measurable current, a lens for focusing the RHEED pattern emanating from the phosphor screen onto the photodiode, an interference filter for filtering out light other than that which emanates from the phosphor screen, a current amplifier for amplifying and convening the current produced by the photodiode into a voltage, a computer for receiving the amplified photodiode current for RHEED data analysis, and a graphite impregnated triax cable for improving the signal to noise ratio obtained while sampling a stationary or rotating substrate. A rotating stage for supporting the substrate with diametrically positioned electron beam apertures and an optically encoded shaft can also be used to accommodate rotation of the substrate during measurement.
    Type: Grant
    Filed: May 3, 1995
    Date of Patent: December 31, 1996
    Assignee: Midwest Research Institute
    Inventor: Peter Sheldon
  • Patent number: 5581346
    Abstract: Apparatus for detecting and mapping defects in the surfaces of polycrystalline material in a manner that distinguishes dislocation pits from grain boundaries includes a first laser of a first wavelength for illuminating a wide spot on the surface of the material, a second laser of a second relatively shorter wavelength for illuminating a relatively narrower spot on the surface of the material, a light integrating sphere with apertures for capturing light scattered by etched dislocation pits in an intermediate range away from specular reflection while allowing light scattered by etched grain boundaries in a near range from specular reflection to pass through, and optical detection devices for detecting and measuring intensities of the respective intermediate scattered light and near specular scattered light. A center blocking aperture or filter can be used to screen out specular reflected light, which would be reflected by nondefect portions of the polycrystalline material surface.
    Type: Grant
    Filed: September 28, 1994
    Date of Patent: December 3, 1996
    Assignee: Midwest Research Institute
    Inventor: Bhushan L. Sopori
  • Patent number: 5577157
    Abstract: An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the wall of the muffle is also provided for controlling the source of optical energy.
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: November 19, 1996
    Assignee: Midwest Research Institute
    Inventor: Bhushan L. Sopori
  • Patent number: 5562420
    Abstract: Airfoils for the blade of a wind turbine wherein each airfoil is characterized by a thickness in a range from 16%-24% and a maximum lift coefficient designed to be largely insensitive to roughness effects. The airfoils include a family of airfoils for a blade 15 to 25 meters in length, a family of airfoils for a blade 1 to 5 meters in length, and a family of airfoils for a blade 5 to 10 meters in length.
    Type: Grant
    Filed: March 14, 1994
    Date of Patent: October 8, 1996
    Assignee: Midwest Research Institute
    Inventors: James L. Tangler, Dan M. Somers
  • Patent number: 5559220
    Abstract: A DNA encoding an acetyl-coenzyme A carboxylase (ACCase) from a photosynthetic organism and functional derivatives thereof which are resistant to inhibition from certain herbicides. This gene can be placed in organisms to increase their fatty acid content or to render them resistant to certain herbicides.
    Type: Grant
    Filed: April 7, 1995
    Date of Patent: September 24, 1996
    Assignee: Midwest Research Institute
    Inventors: Paul G. Roessler, John B. Ohlrogge
  • Patent number: 5544616
    Abstract: A liquid phase epitaxy method for forming thin crystalline layers of device quality silicon having less than 3.times.10.sup.16 Cu atoms/cc impurity, comprising: preparing a saturated liquid solution of Si in a Cu/Al solvent at about 20 to about 40 at. % Si at a temperature range of about 850.degree. to about 1100.degree. C. in an inert gas; immersing or partially immersing a substrate in the saturated liquid solution; super saturating the solution by lowering the temperature of the saturated solution; holding the substrate in the saturated solution for a period of time sufficient to cause Si to precipitate out of solution and form a crystalline layer of Si on the substrate; and withdrawing the substrate from the solution.
    Type: Grant
    Filed: May 27, 1994
    Date of Patent: August 13, 1996
    Assignee: Midwest Research Institute
    Inventors: Theodore F. Ciszek, Tihu Wang
  • Patent number: 5541118
    Abstract: A process for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness.
    Type: Grant
    Filed: May 22, 1995
    Date of Patent: July 30, 1996
    Assignee: Midwest Research Institute
    Inventors: Dean H. Levi, Art J. Nelson, Richard K. Ahrenkiel
  • Patent number: 5536655
    Abstract: The gene encoding Acidothermus cellulolyticus E1 endoglucanase is cloned and expressed in heterologous microorganisms. A new modified E1 endoglucanase enzyme is produced along with variants of the gene and enzyme. The E1 endoglucanase is useful for hydrolyzing cellulose to sugars for simultaneous or later fermentation into alcohol.
    Type: Grant
    Filed: July 15, 1994
    Date of Patent: July 16, 1996
    Assignee: Midwest Research Institute
    Inventors: Steven R. Thomas, Robert A. Laymon, Michael E. Himmel
  • Patent number: 5514584
    Abstract: A process is described for moving fragments that code for cellulase activity from the genome of A. cellulolyticus to several plasmid vectors and the subsequent expression of active cellulase acitivty in E. coli.
    Type: Grant
    Filed: June 27, 1994
    Date of Patent: May 7, 1996
    Assignee: Midwest Research Institute
    Inventors: Stanley M. Lastick, deceased, Melvin P. Tucker, Karel Grohmann
  • Patent number: 5514583
    Abstract: The invention relates to microorganisms which normally do not ferment a pentose sugar and which are genetically altered to ferment this pentose to produce ethanol. A representative example is Zymomonas mobilis which has been transformed with E. coli xylose isomerase, xylulokinase, transaldolase and transketolase genes. Expression of the added genes are under the control of Zymomonas mobilis promoters. This newly created microorganism is useful for fermenting pentoses and glucose, produced by hydrolysis of hemicellulose and cellulose, to produce ethanol.
    Type: Grant
    Filed: April 15, 1994
    Date of Patent: May 7, 1996
    Assignee: Midwest Research Institute
    Inventors: Stephen K. Picataggio, Min Zhang, Christina K. Eddy, Kristine A. Deanda, Mark Finkelstein
  • Patent number: 5503996
    Abstract: The invention relates to the prehydrolysis of lignocellulose by passing an acidic or alkaline solution through solid lignocellulosic particles with removal of soluble components as they are formed. The technique permits a less severe combination of pH, temperature and time than conventional prehydrolysis. Furthermore, greater extraction of both hemicellulose and lignin occurs simultaneously in the same reactor and under the same conditions.
    Type: Grant
    Filed: December 27, 1994
    Date of Patent: April 2, 1996
    Assignee: Midwest Research Institute
    Inventors: Robert W. Torget, Kiran L. Kadam, Teh-An Hsu, George P. Philippidis, Charles E. Wyman
  • Patent number: 5504259
    Abstract: A process for conversion of a feedstock selected from the group consisting of biomass and refuse derived fuel (RDF) to provide reformulated gasoline components comprising a substantial amount of materials selected from the group consisting of ethers, alcohols, or mixtures thereof, comprising: drying said feedstock; subjecting said dried feedstock to fast pyrolysis using a vortex reactor or other means; catalytically cracking vapors resulting from said pyrolysis using a zeolite catalyst; condensing any aromatic byproduct fraction; catalytically alkylating any benzene present in said vapors after condensation; catalytically oligomerizing any remaining ethylene and propylene to higher olefins; isomerizing said olefins to reactive iso-olefins; and catalytically reacting said iso-olefins with an alcohol to form ethers or with water to form alcohols.
    Type: Grant
    Filed: October 29, 1992
    Date of Patent: April 2, 1996
    Assignee: Midwest Research Institute
    Inventors: James P. Diebold, John W. Scahill, Helena L. Chum, Robert J. Evans, Bahman Rejai, Richard L. Bain, Ralph P. Overend
  • Patent number: 5502292
    Abstract: A method for simultaneously cutting and welding ultra-thin foils having a thickness of less than 0.002 inches wherein two ultra-thin films are stacked and clamped together. A pulsed laser such as of the Neodymium: YAG type is provided and the beam of the laser is directed onto the stacked films to cut a channel through the films. The laser is moved relative to the stacked foils to cut the stacked foils at successive locations and to form a plurality of connected weld beads to form a continuous weld.
    Type: Grant
    Filed: August 4, 1994
    Date of Patent: March 26, 1996
    Assignee: Midwest Research Institute
    Inventors: John C. Pernicka, David K. Benson, C. Edwin Tracy
  • Patent number: 5500503
    Abstract: A method of welding an ultra-thin foil to the edge of a thicker sheet to form a vacuum insulation panel comprising the steps of providing an ultra-thin foil having a thickness less than 0.002, providing a top plate having an edge and a bottom plate having an edge, clamping the foil to the edge of the plate wherein the clamps act as heat sinks to distribute heat through the foil, providing a laser, moving the laser relative to the foil and the plate edges to form overlapping weld beads to weld the foil to the plate edges while simultaneously cutting the foil along the weld line formed by the overlapping beads.
    Type: Grant
    Filed: August 4, 1994
    Date of Patent: March 19, 1996
    Assignee: Midwest Research Institute
    Inventors: John C. Pernicka, David K. Benson, C. Edwin Tracy
  • Patent number: 5489321
    Abstract: A method of welding and sealing the edges of two juxtaposed glass sheets together to seal a vacuum space between the sheets comprises the steps of positioning a radiation absorbant material, such as FeO, VO.sub.2, or NiO, between the radiation transmissive glass sheets adjacent the edges and then irradiating the absorbant material, preferably with a laser beam, through at least one of the glass sheets. Heat produced by the absorbed radiation in the absorbant material melts glass in the portions of both glass sheets that are adjacent the absorbant material, and the melted glass from both sheets flows together to create the weld when the melted glass cools and hardens. The absorbant material can be dissolved and diffused into the melted glass to the extent that it no longer absorbs enough energy to keep the glass melted, thus, with appropriate proportioning of absorbant material to source energy power and welding heat needed, the process can be made self-stopping.
    Type: Grant
    Filed: July 14, 1994
    Date of Patent: February 6, 1996
    Assignee: Midwest Research Institute
    Inventors: C. Edwin Tracy, David K. Benson
  • Patent number: 5487792
    Abstract: A protective diffusion barrier having adhesive qualifies for metalized surfaces is provided by a passivating agent having the formula HS--(CH.sub.2).sub.11 --COOH Which forms a very dense, transparent organized molecular assembly or layer that is impervious to water, alkali, and other impurities and corrosive substances that typically attack metal surfaces.
    Type: Grant
    Filed: June 13, 1994
    Date of Patent: January 30, 1996
    Assignee: Midwest Research Institute
    Inventors: David E. King, Alvin W. Czanderna, Cheryl E. Kennedy