Patents by Inventor John Varadarajan

John Varadarajan 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: 7641815
    Abstract: Luminescent materials and the use of such materials in anti-counterfeiting, inventory, photovoltaic, and other applications are described herein. In one embodiment, a luminescent material has the formula: [AaBbXxX?x?X?x?][dopants], wherein A is selected from at least one of elements of Group IA; B is selected from at least one of elements of Group VA, elements of Group IB, elements of Group IIB, elements of Group IIIB, elements of Group IVB, and elements of Group VB; X, X?, and X? are independently selected from at least one of elements of Group VIIB; the dopants include electron acceptors and electron donors; a is in the range of 1 to 9; b is in the range of 1 to 5; and x, x?, and x? have a sum in the range of 1 to 9. The luminescent material exhibits photoluminescence having: (a) a quantum efficiency of at least 20 percent; (b) a spectral width no greater than 100 nm at Full Width at Half Maximum; and (c) a peak emission wavelength in the near infrared range.
    Type: Grant
    Filed: March 21, 2007
    Date of Patent: January 5, 2010
    Assignee: Ultradots, Inc.
    Inventors: John Varadarajan, Mirna Resan, Fanxin Wu, William M. Pfenninger, Nemanja Vockic, John Kenney
  • Publication number: 20080014463
    Abstract: Luminescent materials and the use of such materials in anti-counterfeiting, inventory, photovoltaic, and other applications are described herein. In one embodiment, a luminescent material has the formula: [AaBbXxX?x?X?x?][dopants], wherein A is selected from at least one of elements of Group IA; B is selected from at least one of elements of Group VA, elements of Group IB, elements of Group IIB, elements of Group IIIB, elements of Group IVB, and elements of Group VB; X, X?, and X? are independently selected from at least one of elements of Group VIIB; the dopants include electron acceptors and electron donors; a is in the range of 1 to 9; b is in the range of 1 to 5; and x, x?, and x? have a sum in the range of 1 to 9. The luminescent material exhibits photoluminescence having: (a) a quantum efficiency of at least 20 percent; (b) a spectral width no greater than 100 nm at Full Width at Half Maximum; and (c) a peak emission wavelength in the near infrared range.
    Type: Application
    Filed: March 21, 2007
    Publication date: January 17, 2008
    Inventors: John Varadarajan, Mirna Resan, Fanxin Wu, William Pfenninger, Nemanja Vockic, John Kenney
  • Patent number: 6288224
    Abstract: Aziridines may be subjeted to a cyclooligomerization reaction to produce polyazacycloalkane compounds useful for example in the preparation of chelating agents for use in diagnostic imaging contrast agents. N-benzyl-aziridine in particular is useful as it can be cyclotetramerized and debenzylated to yield cyclen, a key intermediate in chelating agent preparation. The invention provides a particularly attractive route to production of N-benzyl and other N-arylmethyl aziridines of formula (I) where each R1 is independently hydrogen or a group AR and Ar is an optionally substituted phenyl group. The process comprises reacting a purified N-arylmethylethanolamine-sulphonate sulphonate ester with a base. N-aryimethyl-ethanolamine sulphonate ester of the formula R′NHCH2CH2OSO3H, wherein the N-arylmethyl group R′ is an N-(bisarylmethyl) or N-(triarylmethyl) group, as intermediates.
    Type: Grant
    Filed: April 10, 2000
    Date of Patent: September 11, 2001
    Assignees: Nycomed Salutar, Inc., University of Iowa Research Foundation
    Inventors: Janis Vasilevskis, John Varadarajan, Martha Garrity, Jere Douglas Fellmann, Louis Messerle, Gandara Amarasinghe
  • Patent number: 6048979
    Abstract: Aziridines may be subjected to a cyclooligomerization reaction to produce polyazacycloalkane compounds useful for example in the preparation of chelating agents for use in diagnostic imaging contrast agents. N-benzyl-aziridine in particular is useful as it can be cyclotetramerized and debenzylated to yield cyclen, a key intermediate in chelating agent preparation. The invention provides a particularly attractive route to production of N-benzyl and other N-arylmethyl aziridines of formula (I) where each R.sub.1 is independently hydrogen or a group AR and Ar is an optionally substituted phenyl group. The process comprises reacting a purified N-arylmethylethanolaminesulphonate ester with a base. N-arylmethyl-ethanolamine sulphonate ester of the formula R'NHCH.sub.2 CH.sub.2 OSO.sub.3 H, wherein the N-arylmethyl group R' is an N-(bisarylmethyl) or N-(triarylmethyl) group, as intermediates. In a further aspect, the invention provides compounds of formula (II) ##STR1## where Ar and R.sub.
    Type: Grant
    Filed: December 2, 1997
    Date of Patent: April 11, 2000
    Assignees: Nycomed Salutar, Inc., University of Iowa Foundation
    Inventors: Janis Vasilevskis, John Varadarajan, Martha Garrity, Jere Douglas Fellmann, Louis Messerle, Gandara Amarasinghe
  • Patent number: 6045821
    Abstract: The present invention relates to a liposomal agent comprising liposomes having bound to a membrane thereof a chelated diagnostically or therapeutically effective metal ion. The chelating agent binding the metal ion has a macrocyclic chelant moiety with, attached to a single ring atom thereof, a lipophilic membrane associating moiety.
    Type: Grant
    Filed: May 29, 1997
    Date of Patent: April 4, 2000
    Assignee: Nycomed Salutar, Inc.
    Inventors: Martha Garrity, John Varadarajan, Alan David Watson
  • Patent number: 6010681
    Abstract: The invention provides a blood pool contrast agent having an overall molecular weight of at least 10KD comprising a macrostructure which has bound thereto a plurality of opsonization inhibiting moieties and carries chelated ionic paramagnetic or heavy metal moieties, the chelant groups for said chelated moieties being macrocyclic where said macrostructure is liposomal.
    Type: Grant
    Filed: January 21, 1997
    Date of Patent: January 4, 2000
    Assignee: Nycomed Salutar, Inc.
    Inventors: Larry Margerum, Brian Campion, Jere Douglas Fellmann, Martha Garrity, John Varadarajan
  • Patent number: 5798089
    Abstract: The invention provides amphiphilic compounds of the formula (I) Ch--(--L--Ar--(--AH).sub.n).sub.m (where Ch is a hydrophilic chelant moiety or a salt or a chelate thereof); each L is an optionally oxo substituted C.sub.2-25 -alkylene linker wherein at least one CH.sub.2 moiety is replaced by a group X.sup.1 (e.g. L may include a chain sequence, an X.sup.1 (CH.sub.2 CH.sub.2 X.sup.1).sub.u (where u is a positive integer) such as X.sup.1 (CH.sub.2 CH.sub.2 X.sup.1).sub.u, CH.sub.2 X.sup.1 CH.sub.2 CH.sub.2 X.sup.1 CH.sub.2 CH.sub.2 X.sup.1, CH.sub.2 X.sup.1 CH.sub.2 CH.sub.2 X.sup.1 CH.sub.2 CH.sub.2 X.sup.1 CH.sub.2 CH.sub.2 X.sup.1, etc.), and wherein L is optionally interrupted by a metabolizable group M but with the provisos that the terminus of L adjacent Ch is CH.sub.2 and that the terminus of L adjacent Ar is X.sup.1 or a CH.sub.2 group adjacent or separated by one CH.sub.2 from a group X.sup.1 (thus, for example the L--Ar linkage may be L.sup.1 --X.sup.1 --Ar, L.sup.1 --CH.sub.2 --Ar, L.sup.1 --X.sup.
    Type: Grant
    Filed: January 17, 1997
    Date of Patent: August 25, 1998
    Assignee: Nycomed Salutar, Inc.
    Inventors: John Varadarajan, Alan David Watson, Arne Berg
  • Patent number: 5725840
    Abstract: The present invention relates to metabolically labile esters, and to contrast media for X-ray and magnetic resonance imaging comprising these esters. The esters have formula (I): ##STR1## in which R.sup.3 is asteroid residue. The esters contain at least one iodine atom and/or heavy metal atom. The compound are metabolizable to products which are soluble in body fluids and are physiologically acceptable.
    Type: Grant
    Filed: October 4, 1996
    Date of Patent: March 10, 1998
    Assignee: Nycomed Imaging AS
    Inventors: Jo Klaveness, Frode Rise, John Varadarajan, Arne J.o slashed.rgen Aasen
  • Patent number: 5556968
    Abstract: Macrocyclic chelating agents, optionally possessing more than one macrocyclic ring having at least two peptide linkages within the macrocyclic skeleton. The chelating agents are used for the preparation of paramagnetic metal chelates for use as MRI contrast agents.
    Type: Grant
    Filed: May 7, 1993
    Date of Patent: September 17, 1996
    Assignee: Nycomed Salutar, Inc.
    Inventors: Joan F. Carvalho, Shaun P. Crofts, John Varadarajan