University of Pittsburgh

Other

Hui C Liu

Dennis Patrick Curran

Darryl D Coon

Maree Patricia Collis

Augustin T Chen

Leo Ternorutsky

Runkiri P Karunasiri

A removable, plasticizer resistant pressure sensitive composition that is particularly useful for PSA applications on plasticizer containing vinyl films is provided. The pressure sensitive adhesive comprises: (a) at least one hydrophobic monomer; (b) about 0.2 to about 10 wt. % of at least one hydrophilic monomer; (c) about 1 to about 40 wt. % of one partially hydrophilic monomer (d) an effective amount of a crosslinker selected from diallyl maleate or a compound represented by the formula:wherein R is selected from hydrogen, methyl, or ethyl, and R' is selected from vinyl, allyl, or methallyl; wherein the pressure sensitive adhesive does not contain a plasticizer.

Removable pressure sensitive adhesives with plasticizer resistance properties

The present invention provides a short, convergent total synthesis of novel intermediates in the synthesis of (&plusmn;)-camptothecin and related compounds. The present synthesis scheme includes a novel 4&plus;1 radical annulation followed by another cyclization to simultaneously assemble rings B and C of the camptothecin compound. The present invention also provides novel chemical intermediates for such 4&plus;1 radical annulations.

Intermediates in the synthesis of (&plusmn;)-camptothecin and related compounds and synthesis thereof

An A-ring substituted chemical compound has the formula

The present invention provides a short, convergent total synthesis of novel intermediates in the synthesis of (.+-.)-camptothecin and related compounds. The present synthesis scheme includes a novel 4+1 radical annulation followed by another cyclization to simultaneously assemble rings B and C of the camptothecin compound. The present invention also provides novel chemical intermediates for such 4+1 radical annulations.

Intermediates in the synthesis of (.+-.)-camptothecin and related

The present method provides a short, convergent total synthesis of novel intermediates in the synthesis of (.+-.)-camptothecin and related compounds. The synthesis scheme includes a novel 4+1 radical annulation followed by another cyclization to simultaneously assemble rings B and C of the Camptothecin compound. In the synthesis, the following novel precursor is reacted with a phenyl isocyanide: ##STR1## The resulting tetracyclic intermediates comprise a quinoline fused to a pyrrolidine ring, with the pyrrolidine ring being fused to an alpha-pyridone ring. The tetracyclic intermediates thus comprise the A, B, C, and D rings characteristic of camptothecin and camptothecin derivatives, and are easily convertible to camptothecin and camptothecin derivatives via hydroxymethylation and oxidation.

Intermediates in the synthesis of (+) camptothecin and related compounds

A fast, real time method and apparatus for long wavelength infrared photodetection employs a quantum well from which stored electrons are ejected by photoemission and replaced by electrons which tunnel through a barrier bounding one side of the quantum well. The photodetector comprises a semiconductor device having a quantum well layer separated from an emitter layer on one side by a first barrier layer and from a collector layer on the other side by a second barrier layer. The first barrier is higher than the second which in turn is higher than the Fermi level in the quantum well layer. Photons excite electrons in the quantum well to an excited state from which they flow over the second barrier to the collector layer. Electrons tunnel from the emitter through the first barrier to the quantum well at the rate at which they are depleted by photoemission so that the detector is suitable for use with high pulse rate digital communication signals.

Intraband quantum well photodetector and associated method

The present invention relates to a novel semiconductor heterostructure device characterized by improved coupling of tunnelling current to an electromagnetic field in the region between doped conductive layers of the device comprising a first conductive contact layer comprising a semiconductor including a dopant material, a barrier layer in juxtaposition to the first conductive contact layer comprising a semiconductor of a different material than that of the first layer to control the tunnelling current, a non-barrier layer in juxtaposition to the barrier layer comprising an undoped, semiconductor material to provide improved coupling to the electromagnetic field, a second conductive contact layer comprising a semiconductor including a dopant material, and means for applying a bias voltage potential across the device to generate photon emissions. The invention further relates to a method of producing a far infrared and/or microwave radiation source from radiative tunnelling transitions in a semiconductor device having at least one barrier layer and a plurality of doped conductive contact layers comprising the steps of passing an intraband tunnelling current through the device so as to provide that the photon creation rate of said device is larger than the ohmic damping loss rate, and directing the emitted photons from said device so that the device functions as an electromagnetic radiation emitter which provides increased coupling of said tunnelling current to an electromagnetic field located in the region between the doped conductive layers.

Growing community of inventors

Pittsburgh, PA, United States of America

Hui C Liu