RESUMEN
We study electrochemical p- and n-type doping in the well-known light-emitting polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). Doping reactions are characterized using cyclic voltammetry. Optical measurements including photoluminescence and UV/Vis/NIR transmission were performed on doped samples. We find that oxidation in MEH-PPV is a highly reversible reaction resulting in stable freestanding doped films, while the reduced form is unstable and the reaction irreversible. We discuss the dependence of doping reactions on scan rate, film thickness, salt type and concentration, and working electrode type. We observe the development of two additional broad absorption bands in both lightly and heavily doped films accompanied by a slight blueshift in the primary optical transition, suggesting bipolaron band formation. Finally we find that both p and n dopings result in extremely sensitive photoluminescence quenching. We propose a physical model for understanding electrochemical doping in MEH-PPV and the implications this has on the development of such technologies as polymer light-emitting electrochemical cells, electrochromic devices, actuators, and sensors.
RESUMEN
Liver cancer is the fifth most common cancer worldwide and unlike certain other cancers, such as colon cancer, a mutational model has not yet been developed. We have performed gene expression profiling of normal and neoplastic livers in C3H/HeJ mice treated with diethylnitrosamine. Using oligonucleotide microarrays, we compared gene expression in liver tumors to three different states of the normal liver: quiescent adult, regenerating adult, and newborn. Although each comparison revealed hundreds of differentially expressed genes, only 22 genes were found to be deregulated in the tumors in all three comparisons. Three of these genes were examined in human hepatocellular carcinomas and were found to be upregulated. As a second method of analysis, we used Representational Difference Analysis (RDA) to clone mRNA fragments differentially expressed in liver tumors versus regenerating livers. We cloned several novel mRNAs that are differentially regulated in murine liver tumors. Here we report the sequence of a novel cDNA whose expression is upregulated in both murine and human hepatocellular carcinomas. Our results suggest that DEN-treated mice provide an excellent model for human hepatocellular carcinomas.
Asunto(s)
Carcinoma Hepatocelular/genética , Neoplasias Hepáticas Experimentales/genética , Neoplasias Hepáticas/genética , Secuencia de Aminoácidos , Animales , Carcinoma Hepatocelular/metabolismo , Clonación Molecular/métodos , ADN Complementario/genética , ADN Complementario/aislamiento & purificación , Femenino , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas Experimentales/metabolismo , Regeneración Hepática/genética , Masculino , Ratones , Ratones Endogámicos C3H , Datos de Secuencia Molecular , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Regulación hacia ArribaRESUMEN
The purposes of this case study are to report on the successful rehabilitation program of a college football player diagnosed as having a ruptured biceps brachii muscle and to discuss the basic rehabilitation concepts used for treatment planning. A review of the literature indicated agreement that the ruptured biceps brachii is a rare event, but the pathology does occur, and the opportunity for the clinician to evaluate and treat the injury may arise. Following a rupture of the biceps brachii muscle, a player was treated conservatively (nonsurgically) using rehabilitation concepts that included ice during acute phase; heat during chronic phase; submaximal exercise prior to maximal exercise; multiple angle isometric exercise prior to isotonic and isokinetic exercise; and functional progression to field activities. The athlete was able to avoid surgery, successfully return to competition in three weeks, and compete in the final five football games without reinjury. One year follow-up evaluation revealed that the athlete had full strength with no residual problems, a finding not commonly reported in conservatively treated biceps brachii ruptures. J Orthop Sports Phys Ther 1991;13(4):184-190.