Patents by Inventor Stephen A. Wald

Stephen A. Wald 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).

  • Patent number: 5196568
    Abstract: This invention relates to novel compositions of matter which are esters with enhanced water solubility, for use in aqueous enzymatic resolution reactions of racemic mixtures of these esters for producing the separate chiral isomers of the racemic mixture. The invention also relates to novel methods for preparing these esters. The importance of the production of the separate chiral isomers of the racemic mixtures resides in the isolation of the isomers which frequently have different biological activities. Of particular significance regarding the water soluble esters of this invention is that they are derivatized with groups which enhance their aqueous solubility and their reactivity with enzymatic resolving methods which are mediated in an aqueous environment.
    Type: Grant
    Filed: April 7, 1988
    Date of Patent: March 23, 1993
    Assignee: Sepracor, Inc.
    Inventors: Charles M. Zepp, Stephen A. Wald, David R. Dodds
  • Patent number: 5077217
    Abstract: This invention relates to novel methods for facilitating the enzymatic resolution of racemic mixtures of esters, which are derivatized with groups which enhance the esters' aqueous solubility, in an extractive member reactor where the enzyme is placed alternatively either (1) in the aqueous phase, (2) in association with the membrane, or (3) in the aqueous phase and in association with the membrane, wherein the aqueous ester phase is contacted with one side of the membrane, and where an organic extractive phase is contacted with the other side of the membrane, wherein the extractive phase serves to remove the resolving reaction product. Of particular significance regarding this invention is its use of water soluble esters that are derivatized with groups which enhance their aqueous solubility and their reactivity with enzymatic resolving methods which are mediated in an aqueous environment.
    Type: Grant
    Filed: April 7, 1988
    Date of Patent: December 31, 1991
    Assignee: Sepracor, Inc.
    Inventors: Stephen L. Matson, Stephen A. Wald, Charles M. Zepp, David R. Dodds
  • Patent number: 5057427
    Abstract: This invention relates to a novel method of effecting aqueous enzymatic and homogeneous resolutions of racemic esters which exhibit enhanced aqueous solubility. The preferred embodiment of this invention relates to the resolutions which are effected by placing the enzyme and racemic esters in an aqueous phase wherein one of the ester enantiomers is preferentially and stereospecifically de-esterified to effect the resolution of the initial racemic mixture. In another embodiment of this invention, the resolutions are effected by placing the enzyme and racemic esters in an aqueous phase, and contacting this aqueous phase with an organic phase. The preferential and stereospecific de-esterification of one of the ester enantiomers is effected, and the chiral acid product of the de-esterification reaction is extracted into the organic phase.
    Type: Grant
    Filed: April 7, 1988
    Date of Patent: October 15, 1991
    Assignee: Sepracor, Inc.
    Inventors: Stephen A. Wald, Stephen L. Matson, Charles M. Zepp, David R. Dodds
  • Patent number: 4350727
    Abstract: A textile composite is provided which comprises a non-woven textile fabric, composed of textile fibers needled together into a network of coherently entangled fibers and having an overall bulk density of between 4 and 20 lbs. per cubic foot, and a knitted textile fabric, having a weight of between 1 and 8 ozs. per square yard, bound to the needled fabric. The binding of the fabrics is such that at least one tensile property of the composite is greater than the sum of that same property of the non-woven and knitted fabrics. That same property is measurable at an extension which is the same or less than the extension at failure of the composite.
    Type: Grant
    Filed: September 28, 1981
    Date of Patent: September 21, 1982
    Assignee: Lydall, Inc.
    Inventors: Stephen A. Wald, Robert W. Carter
  • Patent number: 4257791
    Abstract: There is provided a filter wherein the filtering means has a non-woven needled textile filter fabric with an overall bulk density of at least 6 pounds per cubic foot and bulk density gradient such that the bulk density at the face surface of the fabric is greater than the bulk density at the back surface of the fabric. In conjunction with that bulk density gradient is a filtering gradient such that the fineness of filtration at the back face surface is greater than the fineness of filtration at the surface. The filter may be in any convenient form, such as the bag of an air conveyor filter or a vacuum cleaner filter.
    Type: Grant
    Filed: August 10, 1979
    Date of Patent: March 24, 1981
    Assignee: Lydall, Inc.
    Inventor: Stephen A. Wald
  • Patent number: 4164400
    Abstract: There is provided a filter wherein the filtering means has a non-woven needled textile filter fabric with an overall bulk density of at least 6 pounds per cubic foot and bulk density gradient such that the bulk density at the face surface of the fabric is greater than the bulk density at the back surface of the fabric. In conjunction with that bulk density gradient is a filtering gradient such that the fineness of filtration at the face surface is greater than the fineness of filtration at the back surface. The filter may be in any convenient form, such as the bag of an air conveyor filter or a vacuum cleaner filter.
    Type: Grant
    Filed: December 21, 1976
    Date of Patent: August 14, 1979
    Assignee: Scott/Chatham Company
    Inventor: Stephen A. Wald
  • Patent number: 4132821
    Abstract: There is provided a non-woven textile composite which simulates the strength, durability, appearance, temper, smooth surface, hand and feel of natural leather and a method of producing the same. The composite includes a non-woven needled textile fabric substrate having a coherent network of randomly entangled textile fibers with an as needled overall bulk density of at least 6 pounds/cubic foot and having a face surface and a back surface, and a geometric center therebetween. A shape-sustaining immobilized polymeric composition is differentially disposed in the substrate such that there is at least 25% more polymeric composition between the face surface and the geometric center than between the back surface and the geometric center. A moldable skin coat layer may be disposed on the face surface. The substrate and the immobilized polymeric composition are in a co-compacted state such that the thickness of the co-compacted substrate and immobilized polymeric composition are less than 0.
    Type: Grant
    Filed: September 22, 1977
    Date of Patent: January 2, 1979
    Assignee: Scott Chatham Company
    Inventors: John J. Hiers, Stephen A. Wald