Time filter

Source Type

Tenorio R.P.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Barros W.,Federal University of Pernambuco
Integrative Biology (United Kingdom) | Year: 2017

We report the use of high-resolution magnetic resonance imaging methods to observe pattern formation in colonies of Saccharomyces cerevisiae. Our results indicate substantial signal loss localized in specific regions of the colony rendering useful imaging contrast. This imaging contrast is recognizable as being due to discontinuities in magnetic susceptibility (χ) between different spatial regions. At the microscopic pixel level, the local variations in the magnetic susceptibility (Δχ) induce a loss in the NMR signal, which was quantified via T2 and T2∗ maps, permitting estimation of Δχ values for different regions of the colony. Interestingly the typical petal/wrinkling patterns present in the colony have a high degree of correlation with the estimated susceptibility distribution. We conclude that the presence of magnetic susceptibility inclusions, together with their spatial arrangement within the colony, may be a potential cause of the susceptibility distribution and therefore the contrast observed on the images. © The Royal Society of Chemistry 2017.


de Paiva J.D.S.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Sousa E.E.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | de Farias E.E.G.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | do Carmo A.M.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | And 2 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2015

Considerable amounts of biological material contaminated with artificial radionuclides were generated to obtain the efficiency curves for low-activity radionuclide analyses of large environmental samples. Likewise, improving detection geometry is also an important task, mainly for studies involving conservation units with a high level of biodiversity preservation. This study aimed to evaluate the Monte Carlo efficiency curves without generating contaminated material with artificial radionuclides for water and vegetation measurements. An in-house adapted Marinelli geometry was applied to reduce the sampled amount of biological material in the ecosystem, which was combined with the Monte Carlo assisted efficiency curve for a more sustainable radiometric analysis. © 2015, Akadémiai Kiadó, Budapest, Hungary.


Oliveira M.L.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Maia A.F.,Federal University of Sergipe
Applied Radiation and Isotopes | Year: 2010

Tandem systems usually comprise two detectors with different radiation energy responses and are utilized to determine the effective energy of unknown radiation beams. The aim of this paper was to evaluate the influence of absorbed dose on tandem curves obtained for different TL materials. In the studied dose interval, the results demonstrate that there is no significant influence of dose on the tandem curves. Therefore, the reliability of these systems for the determination of radiation beam effective energy was confirmed. © 2010 Elsevier Ltd. All rights reserved.


Benevides C.A.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | De Menezes F.D.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | De Araujo R.E.,Federal University of Pernambuco
Applied Optics | Year: 2015

This work evaluated the fluorescent dye degradation indirectly induced by ionizing radiation with high energy photons (50 keV). Aqueous gels of agarose with low concentrations of Rhodamine 6G and Fluorescein were submitted to doses of x-ray radiation up to 200 Gy. The dye degradation was analyzed by fluorescence spectroscopy, using an excitation light-emitting diode with a peak wavelength of 462 nm. A rate equation model of fluorophores and radicals' species populations was developed to describe the degradation time behavior of the fluorescent solutions. The model suggests fluorescent dyes should be used in dosimetry. © 2015 Optical Society of America.


Paschoal C.M.M.,Federal University of Sergipe | Paschoal C.M.M.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Souza D.D.N.,Federal University of Sergipe | Santos L.A.P.,Federal University of Sergipe | Santos L.A.P.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE)
IEEE Transactions on Nuclear Science | Year: 2013

Computed tomography (CT) is a significant source of medical X-ray for the general population. As an alternative method to the 100 mm long ionization chamber, which is normally used to measure the CT dose index (CTDI), some studies use smaller semiconductor photodetectors to measure the single scan dose profile (SSDP). In this case, the CT dose profiles are obtained by scanning the device through the beam using multiple rotations of the X-ray source. Some advantages of using electronic devices as radiation detectors include their high sensitivity, small physical size, no need for high voltage, and the capability of real time measurements. In this study the SSDP was obtained by using a photodiode in two ways: a detector built with only one device, and an innovative detector based on a time-multiplexing signal from an array of 31 photodiodes. Moreover, since most clinical CT examinations involve multiple scans as the patient is translated through the gantry, the novel detector was also used to obtain the multiple scan average dose (MSAD). Unprecedented results provide details of the single slice dose profile and MSAD curves, showing that such an innovative detector would be an advance in CT dosimetry and quality assurance. © 1963-2012 IEEE.


Yano V.F.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Lima F.F.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE)
Cellular and Molecular Biology | Year: 2010

Use of radionuclides in medical practice has grown steadily in recent years due to the introduction of new radiopharmaceuticals and new equipments. This paper presents a survey of nuclear medicine procedures performed in Alagoas, State of Brazil, in order to help establish reference levels for nuclear medicine patients. Data were gathered on the type of radiopharmaceuticals used and administered activity of each kind of examination, and the age and sex of the patients involved over the period 2002-2005. Based on ICRP-60, the effective dose (E) and collective effective dose (Ecol) have been calculated. The results showed an annual increase in the nuclear medicine examinations during the period of study and cardiac scintigraphy are the most common procedure. The results also indicated that the activities administered to patients are higher than the guidance levels of the Basic Safety Standards (BSS) in most of the kind of examinations. The differences found in the administered activities may reflect the differences in the quality assurance programs implemented. It was observed that the Ecol and E/inhabitant are higher than other countries. Therefore, it is suggested that the protocols have been revised in order to reduce the patient dose without reduce the image quality. © 2010 C.M.B. Edition.


Silva J.M.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Villar H.P.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Pimentel R.M.M.,Federal Rural University of Pernambuco
Radiation Physics and Chemistry | Year: 2012

Cells of the mesocarp of mango cultivar Tommy Atkins were analyzed by Transmission Electron Microscope-TEM to evaluate the effects of doses of 0.5 and 1.0. kGy applied immediately after the fruit and after storage for twenty days at a temperature of 12. °C followed by 5 days of simulated marketing at a temperature of 21. °C. No alteration was found in the structure of the cell wall, middle lamella, and plasma membrane of fruits when analyzed immediately after application of doses. The mesocarp cell structure of the cell wall, middle lamella, and the plasma membrane did however undergo changes after storage. Fruits that received a dose of 0.5. kGy displayed slight changes in cell wall structure and slight disintegration of the middle lamella. Fruits that received a dose of 1.0. kGy displayed more severe changes in the structure of the cell wall, greater middle lamella degradation, and displacement of the plasma membrane. © 2012 Elsevier Ltd.


Menezes F.D.,Federal University of Pernambuco | Menezes F.D.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Galembeck A.,Federal University of Pernambuco | Alves Jr. S.,Federal University of Pernambuco
Ultrasonics Sonochemistry | Year: 2011

Luminescent CdTe quantum dots (Qdots) have been produced at few minutes by using a new, simple and fast methodology in an aqueous medium by using ultrasound irradiation to accelerate the process of tellurium reduction. The structural and optical properties were characterized by TEM, XRD, absorption and fluorescence spectrocopy. The produced Qdots are in a strong quantum confinement regime and have only one fluorescence band. Moreover, the nanoparticles seem to be monodispersed, which is in accordance with the fluorescence results. We have developed a simple route for preparing monodispersed CdTe Qdots in an aqueous media. The use of ultrasound allows the morphology to be better controlled and the surfaces defects of Qdots to be reduced. © 2011 Elsevier B.V. All rights reserved.


Silva E.C.,Federal University of Minas Gerais | Khaidukov N.M.,RAS Kurnakov Institute of General and Inorganic Chemistry | Vilela E.C.,Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) | Faria L.O.,Brazilian Nuclear Technology Development Center (CDTN)
Radiation Measurements | Year: 2013

Results of the investigation concerning thermoluminescence (TL) responses to X, gamma and neutron radiation fields for crystals of complex fluoride K 2GdF5 undoped and doped with varying concentrations of Dy3+ ions are presented. Crystals doped with 5.0 at% Dy3+ have shown the most efficient TL response, with a linear response to doses for all the radiation fields. In the X rays range, the maximum TL response has been found to be 15 times more than the response for gamma. The fast and thermal neutron TL outputs were evaluated for K2Gd0.95Y 0.05F5 and the contribution of the gamma component in the TL curve was estimated. © 2013 Elsevier Ltd. All rights reserved.


PubMed | Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) and Federal University of Pernambuco
Type: Journal Article | Journal: Anais da Academia Brasileira de Ciencias | Year: 2016

This work evaluated the effects of ionizing radiation on the physico-chemical and sensory characteristics of the potato cultivar gata (Solanum tuberosum L.), including budding and deterioration, with the end goal of increasing shelf life. For this, four groups of samples were harvested at the maturation stage. Three of them were separately exposed to a Co-60 source, receiving respective doses of 0.10, 0.15 and 2.00 kGy, while the non-irradiated group was kept as a control. All samples were stored for 35 days at 24 C ( 2) and at 39% relative humidity. The following aspects were evaluated: budding, rot, loss of weight, texture, flesh color, moisture, external and internal appearance, aroma, soluble solids, titratable acidity, vitamin C, protein, starch and glucose. The results indicated that 0.15 kGy was the most effective dose to reduce sprouting and post-harvest losses, under the conditions studied.

Loading Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) collaborators
Loading Brazilian Northeast Regional Center of Nuclear Science (CRCN-NE) collaborators