RESUMO
The rapid development of optoelectronic applications for optical-to-electrical conversion has increased the interest in graphene oxide material. Here, graphene oxide films (GOF) were used as source material in an infrared photodetector configuration and the temperature dependence of the electrical conductivity was studied. GOF were prepared by the double-thermal decomposition (DTD) method at 973 K, with a fixed carbonization temperature, in a pyrolysis system, under a controlled nitrogen atmosphere, over quartz substrates. Graphene oxide films were mechanically supported in a photodetector configuration on Bakelite substrates and electrically contacted with copper wires and high-purity silver paint. Morphological images from the GOF's surface were taken employing a scanning electron microscope and observed a homogeneous surface which favored the electrical contacts deposition. Vibrational characteristics were studied employing Raman spectroscopy and determined the typical graphene oxide bands. GOF were used to discuss the effect of temperature on the film's electrical conductivity. Current-voltage (I-V) curves were taken for several temperatures varying from 20 to 300 K and the electrical resistance values were obtained from 142.86 to 2.14 kΩ. The GOF electrical conductivity and bandgap energy (Eg) were calculated, and it was found that when increasing temperature, the electrical conductivity increased from 30.33 to 2023.97 S/m, similar to a semiconductor material, and Eg shows a nonlinear change from 0.33 to 0.12 eV, with the increasing temperature. Conduction mechanism was described mainly by three-dimensional variable range hopping (3D VRH). Additionally, measurements of voltage and electrical resistance, as a function of wavelength were considered, for a spectral range between 1300 and 3000 nm. It was evidenced that as the wavelength becomes longer, a greater number of free electrons are generated, which contributes to the electrical current. The external quantum efficiency (EQE) was determined for this proposed photodetector prototype, obtaining a value of 40%, similar to those reported for commercial semiconductor photodetectors. This study provides a groundwork for further development of graphene oxide films with high conductivity in large-scale preparation.
RESUMO
Sufficient epidemiologic evidence has established an etiologic link between bladder cancer risk and occupational exposure as a painter to organic solvents. Currently, it remains to be established whether gene-specific promoter methylation contributes to bladder cancer development, including by enhancing chromosome breakage or loss. We investigated the effect of chronic exposure to organic solvents and paints on DNA methylation profiles in the promoter regions of four genes (GSTP1, p16(INK4a), APC and CDH1) and micronucleus (MN) frequency in exfoliated urothelial cells from voided urine from Colombian male non-smoking car painters and age-matched unexposed individuals. The exposed group had a higher percentage of individuals with >2 MNs/2000 cells compared with the unexposed group (P=0.04). Gene-specific analysis showed a significantly higher percentage of individuals with methylated GSTP1, p16(INK4a) and APC in the exposed group. Poisson regression analysis indicated that exposed individuals with methylated GSTP1 and p16(INK4a) promoters were more than twofold more likely to have an increase in MN frequency as compared with the reference. Finally, among exposed individuals with GSTP1 and p16(INK4a) methylated promoters, those with a greater age had a higher RR of increased MN frequency compared with younger exposed individuals with methylated promoters. These results support the conclusion that gene-specific promoter methylation may increase MN frequency in a dependent or independent interaction with occupational exposure to organic solvents.
Assuntos
Metilação de DNA , Testes para Micronúcleos , Exposição Ocupacional , Pintura/toxicidade , Regiões Promotoras Genéticas , Solventes/toxicidade , Urotélio/efeitos dos fármacos , Humanos , Masculino , Urotélio/citologiaRESUMO
Se presenta una paciente de 34 años, que después del segundo embarazo comenzó la ingesta de anovulatorios (Etinilestradiol-levonorgestrel durante 5 años, en el transcurso del tercer año notó la aparición del cuadro de telangiectasia nevoide unilateral, que actualmente se lo relaciona con cambios estrogénicos fisiológicos o patalogicos, sin embargo su fisiopatología no esta totalmente aclarada.
Assuntos
Humanos , Feminino , Adulto , Ombro/patologia , Telangiectasia/diagnóstico , Telangiectasia/fisiopatologia , Etinilestradiol/efeitos adversos , Levanogestrel/efeitos adversosRESUMO
Se presenta una paciente de 36 años de edad con un tatuaje accidental por incrustación de pintura en la cara, secundario a un accidente automovilístico hace 20 años. Se realiza una revisión del tema,desde sus orígenes, implicancias culturales, técnicas utilizadas, clasificación, complicaciones y métodos de remoción.
Assuntos
Humanos , Feminino , Adulto , Consequências de Acidentes , Tatuagem , Tatuagem/classificação , Tatuagem/psicologia , FaceRESUMO
Se presenta una paciente de 34 años, que después del segundo embarazo comenzó la ingesta de anovulatorios (Etinilestradiol-levonorgestrel durante 5 años, en el transcurso del tercer año notó la aparición del cuadro de telangiectasia nevoide unilateral, que actualmente se lo relaciona con cambios estrogénicos fisiológicos o patalogicos, sin embargo su fisiopatología no esta totalmente aclarada. (AU)
Assuntos
Humanos , Feminino , Adulto , Telangiectasia/diagnóstico , Telangiectasia/fisiopatologia , Ombro/patologia , Etinilestradiol/efeitos adversos , Levanogestrel/efeitos adversosRESUMO
Se presenta una paciente de 36 años de edad con un tatuaje accidental por incrustación de pintura en la cara, secundario a un accidente automovilístico hace 20 años. Se realiza una revisión del tema,desde sus orígenes, implicancias culturales, técnicas utilizadas, clasificación, complicaciones y métodos de remoción. (AU)
Assuntos
Humanos , Feminino , Adulto , Consequências de Acidentes , Tatuagem/classificação , Tatuagem/métodos , Tatuagem/psicologia , FaceRESUMO
The purpose of this study was to evaluate serum levels of TNF-alpha in patients with either of the three clinical forms of American cutaneous leishmaniasis. The 86 patients examined were classified as having either the localized (LCL: 22 patients), mucocutaneous (MCL: 45 patients), or the rare diffuse (DCL: 19 patients) form of the disease. Our results show a significant increase in the mean level of TNF-alpha in the three groups of patients when compared to controls. MCL patients produce significantly higher levels of TNF-alpha than DCL patients. The proportion of individuals positive for serum TNF-alpha was significantly higher in both MCL and DCL patients than in the controls. No significant differences were found in the level of TNF-alpha when compared between before and after cure of 12 patients with MCL. There were no significant correlations between the level of TNF-alpha and the skin test diameter. The results will be discussed in terms of the pathogenesis of the disease in its different clinical forms.
Assuntos
Leishmaniose Cutânea/sangue , Fator de Necrose Tumoral alfa/análise , Adolescente , Adulto , Animais , Antígenos de Protozoários/imunologia , Feminino , Humanos , Hipersensibilidade Tardia/imunologia , Leishmania/imunologia , Leishmaniose Tegumentar Difusa/sangue , Leishmaniose Mucocutânea/sangue , Masculino , Pessoa de Meia-Idade , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Active visceral leishmaniasis is associated with antigen-specific immuno-suppression. However, cured patients develop a cellular immune response associated with resistance to reinfection. Recent studies have identified patients with asymptomatic or subclinical infections, which are also accompanied by an immune response. In order to identify subjects immune to Leishmania chagasi, we performed a skin-test survey in an endemic area in eastern Venezuela. The delayed-type hypersensitivity (DTH) response was assessed in patients cured of visceral leishmaniasis, as well as in their relatives and neighbors. Of the latter, 36 (34.2%) of 105 were positive and 26 (24.7%) of 105 gave intermediate responses. The DTH reaction correlated with age. The antigens recognized by a subgroup of cured patients, those with positive skin-test results, and controls (skin-test negative) were assessed by Western blotting with sera, and T cell immunoblotting with peripheral blood mononuclear cells. No consistent differences between the groups were noted in Western blots with L. chagasi antigens. T cell blots were performed on five patients from each group. For the cured patients and skin-test positive contacts, a significant proliferative response to fraction 12 (less than 20.5 kDa) was noted in four of five patients in each group. Cells from three of five cured patients and two of five skin-test-positive patients proliferated in response to fraction 4 (73-115 kDa). The response to other fractions was variable, with only a minority of patients responding to any one fraction. These data suggest that the antigens recognized by patients with evidence of immunity to L. chagasi are quite variable.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Antígenos de Protozoários/imunologia , Leishmania donovani/imunologia , Leishmaniose Visceral/imunologia , Adolescente , Adulto , Animais , Western Blotting , Distribuição de Qui-Quadrado , Criança , Pré-Escolar , Saúde da Família , Feminino , Humanos , Imunidade Celular , Immunoblotting , Masculino , Recidiva , Testes Cutâneos , Linfócitos T/imunologia , VenezuelaRESUMO
En el presente trabajo nos hemos propuesto dos objetivos principales, primero la evaluación de ciertos aspectos de la regulación de la respuesta inmune en pacientes examinados indirectamente, el papel de las prostaglandinas mediante el uso de indometacina la cual es un inhibidor de su síntesis. En segundo término la cuantificación de diferentes poblaciones de células linfoides: linfocitos T, así como de células no linfoides: monocitos (MO2) mediante el uso de anticuerpos monoclonales y la técnica de inmunoperoxidasa. Para el estudio se utilizaron 84 pacientes con LCA.
Assuntos
Adolescente , Adulto , Humanos , Masculino , Feminino , Indometacina/uso terapêutico , Leishmaniose/diagnóstico , Linfócitos/imunologia , Anticorpos Monoclonais/imunologiaRESUMO
Se investigaron algunos aspectos sobre el efecto inmunomodulador del interferón * en la respuesta linfoproliferativa frente a mitógenos y antígenos de Leishmania, de las células mononucleares provenientes de los pacientes con leishmaniasis cutánea localizada (LCL) y leishmaniasis cutánea mucosa (LCM). Asimismo se evaluó la producción de IFN ipsilón en sobrenadantes estimulados con PHA y antígenos del parásito, preparados a partir de las células de estos mismos pacientes. Nuestros resultados sugieren que los pacientes con LCM no parecen ser susceptibles al efecto modulador del IFN * en respuesta a mitógenos y antígenos, como sí parecen serlo los pacientes con LCL. Además, se encontró que los pacientes con LCL y LCM producen niveles significativos de IFN ipsilón en los sobrenadantes estimulados con PHA y antígenos parasitarios, comparados con los sobrenadantes no estimulados. Sin embargo, la producción de IFN ipsilón en los sobrenadantes de los pacientes con LCM fue significativamente mayor que en los pacientes con LCL. Estos resultados pueden ayudar a explicar parcialmente el estado de hipersensibilidad y daño en las mucosas que presentan los pacientes con LCM