Quantificação da resoluçao do sistema SPECT-CZT através do uso da função de transferência modulada (MTF)

Pós-graduação em Biologia Geral e Aplicada - IBB

Luminescence Enhancement of Carboxyl-Coated CdTe Quantum Dots by Silver Nanoparticles

Metallic nanoparticles (NPs) have been used to improve the sensibility of biosensors and bioassays either by enhancing radiative emission or inducing quenching process on fluorescent probes. The aim of this research was to study the interaction of silver and silver-pectin NPs with water-dispersed carboxyl-coated cadmium telluride (CdTe) quantum dots (QDs). Metallic NPs were observed to change the emission of these fluorophores through local field effects. In a solution-base platform, an increase of 82 % was observed for the CdTe emission due to the interaction of QDs and silver-pectin NPs. QDs interaction with silver NPs without pectin was also investigated and a smaller emission enhancement of 20 % was detected. We observed that the NPs' nature and QDs' surface charge and concentration are important parameters for NPs-QDs interaction. Moreover, the presence of the pectin polymer shows to be a key component to the observed fluorescence enhancement. © 2013 Springer Science+Business Media New York.

Construção e caracterização de células solares de filmes finos de CdS e CdTe

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Gama Câmara CZT: alteração de paradigmas em aquisição de imagens de medicina nuclear

Nuclear medicine is a medical specialty related to imagery that deals with imaging techniques, diagnosis and therapy, allowing observing the physiological state of tissues noninvasively by marking the molecules participating of these physiological processes with radioactive isotopes, thus creating the called radionuclides. The image of a radionuclide is one of the most important applications of radioactivity in nuclear medicine. The equipment’s of nuclear medicine imaging use the principle of radiation detection, turning it into an electrical signal which, through specific algorithms, allows forming tomographic images that provide information about the functional status of organs. New detection systems have been developed for tomographic acquisitions using solid state detectors. These devices use crystals of cadmium zinc telluride (CdZnTe). Some of the advantages of this detector are a significant improvement of signal to noise ratio, the increased spectral and spatial resolution, which in sum, result in greater clarity of the images obtained, opening new perspectives for imaging protocols previously unattainable. In contrast, all other gamma-cameras equipped with vacuum tubes have remained relatively unchanged for nearly fifty years. In these gamma-cameras, the images are obtained using two steps significantly less efficient: the gamma rays are converted to light through a first device, and then the light is converted into an electrical signal through a second device. One of functions the Medical Physicist is related to the quality control of equipment. This control ensures that the information and images provided are true and thus credible to be used in medical reports. To perform this type of analysis the physicist must understand the performance characteristics and operation of all equipment of the department concerned; besides, in the absence of specific legislation, proposing...(Complete abstract click electronic access below)

Cadmium availability and accumulation by lettuce and rice

Among the toxic elements, Cd has received considerable attention in view of its association with a number of human health problems. The objectives of this study were to evaluate the Cd availability and accumulation in soil, transfer rate and toxicity in lettuce and rice plants grown in a Cd-contaminated Typic Hapludox. Two simultaneous greenhouse experiments with lettuce and rice test plants were conducted in a randomized complete block design with four replications. The treatments consisted of four Cd rates (CdCl2), 0.0; 1.3; 3.0 and 6.0 mg kg(-1), based on the guidelines recommended by the Environmental Agency of the State of São Paulo, Brazil (Cetesb). Higher Cd rates increased extractable Cd (using Mehlich-3, Mehlich-1 and DTPA chemical extractants) and decreased lettuce and rice dry matter yields. However, no visual toxicity symptoms were observed in plants. Mehlich-1, Mehlich-3 and DTPA extractants were effective in predicting soil Cd availability as well as the Cd concentration and accumulation in plant parts. Cadmium concentration in rice remained below the threshold for human consumption established by Brazilian legislation. on the other hand, lettuce Cd concentration in edible parts exceeded the acceptable limit.

Bis[(4-methylphenyl)ethynyl] telluride

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modified LPE system used to diffuse Cd to obtain InSb infrared detectors

We are presenting here p/n junctions obtained with a modified opened liquid-phase epitaxy (LPE) system, used to diffuse indium antimonide (InSb) doped with Cd over InSb doped with Te wafers, in order to make InSb infrared (IR) sensors. This technique has several advantages: the diffusion can be performed in bigger substrate areas improving the device production; this method decreases the device manipulation, decreasing human mistakes and increasing the process reproducibility. The opened LPE in this work produced sensors in the first case with vapor of the diffusion material, coming from a microholed carbon boat full of the diffusion material, over which is positioned the substrate at atmospheric pressure. In the second, the diffusion material is on the bottom of a quartz recipient, and the InSb/Te wafer works as its cover, and vacuum was used. The IR sensors produced with the first method measured 8.9 x 10(7) cm Hz(1/2)/W as detectivity value and higher IR spectral response at 4.6 mu m, and those produced with the second 2.8 x 10(9) cm Hz(1/2)/W, at 4.4 mu m. Besides the electrical-optical properties, the structural properties of diffused layers were investigated by X-ray diffraction (XRD), scanning electron and atomic force microscopy (SEM, AFM), energy-dispersive and secondary ion mass spectroscopy (EDS, SIMS). (C) 2007 Elsevier B.V. All rights reserved.

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Deposition of Lead and Cadmium Released by Cigarette Smoke in Dental Structures and Resin Composite

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Oxidative stress biomarkers and aggressive behavior in fish exposed to aquatic cadmium contamination

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Early Changes Induced by Short-Term Low-Dose Cadmium Exposure in Rat Ventral and Dorsolateral Prostates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

SPERM QUALITY IN ADULT MALE RATS EXPOSED TO CADMIUM IN UTERO and LACTATION

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The use of the oxidative stress responses as biomarkers in Nile tilapia (Oreochromis niloticus) exposed to in vivo cadmium contamination

Water contaminants have a high potential risk for the health of populations. Protection from toxic effects of environmental water pollutants primarily involves considering the mechanism of low level toxicity and likely biological effects in organisms who live in these polluted waters. The biomarkers assessment of oxidative stress and metabolic alterations to cadmium exposure were evaluated in Nile tilapia, Oreochromis niloticus. The fish were exposed to 0.35, 0.75, 1.5, and 3.0 mg/l concentrations of Cd2+ (CdCl2) in water for 60 days. Fish that survived cadmium exposure showed a metabolic shift and a compensatory development for maintenance of the body weight gain. We observed a decreased glycogen content and decreased glucose uptake in white muscle. Lactate dehydrogenase (LDH) and creatine phosphokinase (CK) activities were also decreased, indicating that the glycolytic capacity was decreased in this tissue. No alterations were observed in total protein content in white muscle due to cadmium exposure suggesting a metabolic shift of carbohydrate metabolism to maintenance of the muscle protein reserve. There was an increase in glucose uptake, CK increased activity, and a clear increase of LDH activity in red muscle of fish with cadmium exposure. Since no alterations were observed in lipoperoxide concentration, while antioxidant enzymes glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were changed in the liver and the red and white muscle of fish with cadmium exposure, we can conclude that oxygen free radicals are produced as a mediator of cadmium toxicity. Resistance development is related with increased activities of antioxidant enzymes, which were important in the protection against cadmium damage, inhibiting lipoperoxide formation. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Effect of alpha-tocopherol on superoxide radical and toxicity of cadmium exposure

Contamination with cadmium compounds poses high potential risk for the health of populations and for this reason the treatment of their toxic effects should urgently be established. The present study was carried out to determine whether or-tocopherol intake can protect tissues against damage induced by cadmium, and to clarify the contribution of superoxide radicals (O-2(-)) in this process. Cadmium chloride was tested for tissue damage by a single intraperitoneal injection of Cd2+ ions (2 mg Kg(-1)). To determine the potential therapeutic effect of Vitamin E, a group of Cd2+-treated rats received a drinking solution of or-tocopherol (40 mg l(-1)) for 15 days. Cadmium induced increased serum creatinine and total lactate dehydrogenase, reflecting renal and cardiac damage. The increased lipoperoxide and decreased Cu-Zn superoxide dismutase levels indicated the generation of superoxide radicals in cadmium-treated rats. Tocopherol induced increased serum high-density lipoprotein and depressed the toxic effects of Ca2+ alone, since creatinine and lactate dehydrogenase determinations were recovered to the control values. Tocopherol decreased lipoperoxide and led the superoxide dismutase activities to approach those of the control values. We concluded that superoxide radicals are produced as mediators of cadmium toxicity. Tocopherol possesses a significant anti-radical activity and inhibits the cadmium effect on superoxide dismutase activity. Tocopherol also protected tissues from the toxic effects of cadmium by a direct antioxidant action which decreased lipoperoxide formation.

Risk assessment of cadmium toxicity on hepatic and renal tissues of rats

Pollution and industrial practices result in concentrations of metals and other environmental agents that are related to environmental toxicity. A rat bioassay was utilized for the identification of toxic effects of cadmium intake. This demonstrated increased total urinary proteins and increased kidney weights in rats exposed to CdCl2, for 7 days, in drinking water (100 mg/L). Serum creatinine, total and direct bilirubin concentrations and alanine transaminase activity were increased in Cd-exposed rats, indicating renal and hepatic toxicity. It was also observed that lipoperoxide concentrations were increased, while Cu-Zn superoxide dismutase activity was decreased in rats treated with cadmium. This indicated that the renal and hepatic toxicity induced by cadmium involved superoxide radicals. (C) 1998 Academic Press.