Stability, edge passivation effect, electronic and transport properties of POPGraphene nanoribbons.

POPGraphene is a theoretically predicted 2D carbon allotrope which presents a unit cell with 5-8-5 carbon rings. It presents metallic behavior and has a low diffusion energy barrier, which suggests applications as an anode material in batteries. Motivated by the fact that nanoribbons present different properties to their 2D counterparts, in this work two kinds of POPGraphene nanoribbons were proposed, with (POPGNRH) and without (POPGNR) hydrogen edge passivation, and their electronic and transport properties were investigated, in order to characterize them and verify the influence of hydrogen edge passivation. Density functional theory was employed for structure optimization and combined with the Non-Equilibrium Green's Function to obtain the electronic transport properties. We predict that both nanoribbons are stable and can be obtained experimentally. Furthermore, hydrogen passivation reduces the bands around the Fermi level and shift them toward the region of negative energies, which can be seen from the presence of NDR in the transport properties of the hydrogenated device. The electronic transport properties suggest that POPGNR shows Field effect transistor behavior in the analyzed range and POPGNRH shows the same behavior, but in the range of -0.70 V to 0.70 V. Also, due to the presence of NDR, POPGNRH presents Resonant Tunneling Diode behavior in the range of ±0.70 V to ±1.00 V. Therefore, the results suggest applications for both nanoribbons in the field of molecular electronics.

Molecular junction by tunneling in 1D and quasi-1D systems.

We have investigated electron tunneling through two one-dimensional (1D) molecular junctions based on first-principles simulations using the density functional theory combined with the non-equilibrium Green's functions methodology. The first junction, composed of left and right carbyne wire electrodes with a sodium atom in between, is atomically thin. The second one is quasi-one-dimensional (quasi-1D) and consists of two single-wall carbon nanotube electrodes, closed on the tips and again a sodium atom in the scattering region. Although the bridging atom bonds weakly to the electrodes in both systems, it strongly affects the electronic transport properties, such as electron transmission, current-voltage relation, differential conductance, density of states and eigenchannels. This is demonstrated by comparing with the results obtained from the corresponding systems for both the 1D and the quasi-1D junctions in the absence of the central sodium atom. The revealed transport properties are sensitive to the molecular geometry. This helps future molecular electronic device design.

In Vivo Tracking of Cell Therapies for Cardiac Diseases with Nuclear Medicine.

Even though heart diseases are amongst the main causes of mortality and morbidity in the world, existing treatments are limited in restoring cardiac lesions. Cell transplantations, originally developed for the treatment of hematologic ailments, are presently being explored in preclinical and clinical trials for cardiac diseases. Nonetheless, little is known about the possible efficacy and mechanisms for these therapies and they are the center of continuous investigation. In this scenario, noninvasive imaging techniques lead to greater comprehension of cell therapies. Radiopharmaceutical cell labeling, firstly developed to track leukocytes, has been used successfully to evaluate the migration of cell therapies for myocardial diseases. A substantial rise in the amount of reports employing this methodology has taken place in the previous years. We will review the diverse radiopharmaceuticals, imaging modalities, and results of experimental and clinical studies published until now. Also, we report on current limitations and potential advances of radiopharmaceutical labeling for cell therapies in cardiac diseases.

PET/TC em câncer de pulmão: indicações, achados e perspectivas futuras / PET/CT in lung cancer: indications, findings and future perspectives

A utilização do PET-CT com FDG rapidamente se tornou uma importante ferramenta para a melhor caracterização de nódulo pulmonar solitário e no manejo do câncer de pulmão. A sensibilidade e especificidade desta modalidade não invasiva são maiores em comparação a outras técnicas de imagens convencionais, como a tomografia computadorizada. As vantagens e as limitações do método já estão bem estabelecidas, contudo, novas considerações da aplicabilidade estão sendo analisadas. Este artigo objetiva sintetizar os princípios básicos, indicações e perspectivas futuras do PET-CT na determinação de nódulo pulmonar solitário e no manejo do câncer de pulmão.

FDG PET-CT has quickly became an important tool to better characterize solitary pulmonary nodule and for the management of lung cancer. The sensitivity and specificity of this non-invasive technique is superior compared to others conventional imaging, like computed tomography. The advantages and limitations of the PET-CT are well established, however, new considerations of its application are being analyzed. This article aims to summarize the basic principles, indications and future perspectives of PET-CT in determining the solitary pulmonary nodule and the lung cancer management.