Patents by Inventor Dennis S. Donald

Dennis S. Donald has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Process for rapid access development of silver halide films using pyridinium as development accelerators
    Patent number: 5384232
    Abstract: A process of developing exposed silver halide elements comprises developing said element in a developer in the presence of a development accelerator compound as defined. The development accelerator compounds include pyridinium, or pyridinium and and imidazolium compounds. The process is applicable to standard and hydrazine-containing films and to hydroquinone and/or ascorbic acid-based developers. The development accelerator may be incorporated into the developer or into the silver halide emulsion.
    Type: Grant
    Filed: March 30, 1993
    Date of Patent: January 24, 1995
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Julie C. Bishop, Dominic M. Chan, Dennis S. Donald, Ludovic Fodor, William R. Pangratz, Glenn M. Russo, John R. Shock
  • Nonlinear optical materials
    Patent number: 5312565
    Abstract: Novel organic glass compositions are disclosed which are poled to achieve nonlinear optical properties. Novel compounds useful for making said poled compositions are also disclosed; as are a method and a device for transforming electromagnetic radiation using a nonlinear optical element formed from said compositions; and certain intermediates for making novel compounds.
    Type: Grant
    Filed: May 8, 1991
    Date of Patent: May 17, 1994
    Assignee: E. I. duPont de Nemours and Company
    Inventors: Richard Beckerbauer, Dennis S. Donald, Wilson Tam, Frederick C. Zumsteg, Jr.
  • Organic optical elements and nonlinear optical devices
    Patent number: 5145610
    Abstract: Optical elements comprising noncentrosymmetric crystalline organic compounds are provided, that are capable of second harmonic generation. The invention further provides for nonlinear optical devices and modulators incorporating the optical elements.
    Type: Grant
    Filed: November 27, 1989
    Date of Patent: September 8, 1992
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Dennis S. Donald, Gerald R. Meredith
  • Tanning development in low silver photoimaging using polymeric couplers
    Patent number: 4576894
    Abstract: A photoimaging system and method for photoimaging employing said photoimaging system, the latter comprising (i) a photosensitive element having a substrate coated with a photosensitive layer containing dispersed silver halide particles in operative association with a continuous film-forming phase of polymeric coupler, the coupler characterized by the ability to couple with the developing agent of component (ii) to become insoluble in aqueous media; and (ii) an oxidized hydroquinone or aminophenol-type developing agent.
    Type: Grant
    Filed: September 24, 1984
    Date of Patent: March 18, 1986
    Assignee: E. I. Du Pont De Nemours and Company
    Inventor: Dennis S. Donald
  • Phenylmercaptotetrazolo- and nitroindazolo masked development/image modifiers
    Patent number: 4501896
    Abstract: Novel nitrobenzyl compounds are incorporated into a photographic emulsion or developer for controlled release of development/image modifier compounds. This occurs imagewise only after developer oxidation products have been formed in the course of the development process. For example, nitrobenzyl-masked phenylmercaptotetrazole (PMT), incorporated into a silver halide emulsion, reacts with developer oxidation products via an electron transfer mechanism to release the potent development restrainer PMT.
    Type: Grant
    Filed: August 6, 1981
    Date of Patent: February 26, 1985
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Dennis S. Donald, Ross A. Lee
  • Masked development/image modifier compounds of silver photographic systems
    Patent number: 4343893
    Abstract: Novel nitrobenzyl compounds are incorporated into a photographic emulsion or developer for controlled release of development/image modifier compounds. This occurs imagewise only after developer oxidation products have been formed in the course of the development process. For example, nitrobenzyl-masked phenylmercaptotetrazole (PMT), incorporated into a silver halide emulsion, reacts with developer oxidation products via an electron transfer mechanism to release the potent development restrainer PMT.
    Type: Grant
    Filed: July 25, 1980
    Date of Patent: August 10, 1982
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Dennis S. Donald, Ross A. Lee
  • Bis(substituted amino)sulfides as reversible inhibitor sources for photopolymerization
    Patent number: 4168981
    Abstract: Photopolymerizable coating compositions which contain an ethylenically unsaturated polymerizable compound and a radiation sensitive, free-radical generating system are thermally stabilized to inhibit polymerization at elevated temperature without affecting room temperature photopolymerization by adding to the composition a bis(substituted amino)monosulfide or bis(substituted amino)polysulfide.
    Type: Grant
    Filed: April 14, 1977
    Date of Patent: September 25, 1979
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Dennis S. Donald, Peter K. Sysak
  • Synthesis of 3,5-diaminopyrazinoic acid from 3,5-diamino-2,6-dicyanopyrazine and intermediates
    Patent number: 3948895
    Abstract: An improved method for the preparation of 3,5-diaminopyrazinoic acid (which is useful for the manufacture of diuretics) is described. New compounds obtained in the process include 3,5-diamino-2,6-dicarbamoylpyrazine; 3.5-diamino-6-carbamoylpyrazinoic acid and 3,5-diamino-6-carbamoylpyrazine. The latter compounds are also useful as curing agents for epoxy resins.
    Type: Grant
    Filed: March 6, 1972
    Date of Patent: April 6, 1976
    Assignee: E. I. Du Pont de Nemours and Company
    Inventor: Dennis S. Donald