Patents by Inventor Howard L. Ashmead

Howard L. Ashmead 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).

  • Method for producing a gradient elution
    Patent number: RE29454
    Abstract: The method of proportioning two liquids comprising periodically controlling the operation of a valving .[.means.]. .Iadd.arrangement .Iaddend.to control the amount of each liquid supplied to a mixing region during each period of valve operation to produce a supply of eluent having a precisely controlled time varying concentration of each liquid.
    Type: Grant
    Filed: February 20, 1976
    Date of Patent: October 25, 1977
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Howard L. Ashmead, Sydnor H. Byrne, Jr., John P. Wolf, III