Ab-initio and CVM calculations on the metastable fcc, hcp, and bcc Pb-Bi-Te and Pb-Bi-Po ternary systems.

A molten Pb Bi alloy will be used as coolant in MYRRHA (Multi-purpose hybrid research reactor for high-tech applications), a prototype of an accelerator-driven nuclear fission reactor (“generation IV reactor”) that will be built at the Belgian Nuclear Research Center (start of construction in 2015, start of operation in 2025). Neutron capture by 209-Bi will inevitably lead to the appearance of 210-Po in the coolant (about 2 kg in the entire coolant volume of MYRRHA). In order to study interactions of Po with the coolant, knowledge of the Pb Bi Po phase diagram is required. Knowledge of the Pb Bi Te phase diagram is also desirable, since Po-containing systems, due to the high radiotoxicity of Po, are difficult to investigate experimentally. Therefore, analogies with the Pb Bi Te ternary system could lead indirectly to a better understanding also of the Pb Bi Po system

Estudio epidemiológico de cáncer en la adolescencia en centro de referencia

OBJECTIVE: To analyze the epidemiological characteristics of adolescents with cancer referred to an oncologic center, between 2000 and 2006. METHODS: A retrospective descriptive study was carried out in order to evaluate the epidemiological data of patients aged between ten and 19 years at diagnosis and admitted at the Institute of Oncology (IOP/Graacc) of Universidade Federal de São Paulo (UNIFESP), Brazil, between 2000 and 2006. RESULTS: Among 2,362 patients admitted during this period with a diagnosis of cancer, 629 (26.6%) were adolescents. Mean age was 13.7 years, being 56.8% male. Regarding race, 60.7% of the patients were white, 30% mulattoes, 6.5% blacks, and 2.5% of patients had no characterization of race in the medical records. The most frequent types of tumors were: central nervous system tumors (22.1%), osteosarcoma (14.6%), lymphoma (14.5%), and leukemia (14.5%). The overall survival at five years was 73.7%. Adolescents with the diagnosis of rhabdomyosarcoma presented disseminated disease and histology of worse prognosis, which contributed for increasing the mortality rate of this group of patients. CONCLUSIONS: Adolescents with cancer are a group of patients with distinct characteristics when compared to other cancer groups. Our results show differences in the prevalence of tumors during adolescence and childhood, in the later leukemias and central nervous system tumors predominate. It is crucial to facilitate the access of adolescents to oncologic centers in order to provide early diagnosis and proper treatment.OBJETIVO: Analizar las características epidemiológicas de los adolescentes portadores de neoplasias encaminados al Instituto de Oncología Pediátrica (IOP/GRAACC) de la Universidad Federal de São Paulo, entre los años 2000 a 2006. MÉTODOS: Se trata de un estudio retrospectivo descriptivo, en el que fueron evaluados los datos epidemiológicos de los pacientes, con edad entre 10 y 19 años al diagnóstico, admitidos entre los años de 2000 y 2006 en el IOP/GRAACC. RESULTADOS: Del total de 2.362 pacientes admitidos en ese periodo con diagnóstico de cáncer, 629 (26,6%) eran adolescentes. El promedio de edad fue de 13,8 años, siendo la mayoría del sexo masculino (56,8%). Respecto a la raza, 60,7% de los pacientes eran blancos. Los tipos de tumores más frecuentes fueron: tumores de sistema nervioso central (22,1%), osteosarcoma (14,6%), linfomas (14,5%) y leucemias (14,5%). La sobrevida global en cinco años de los 629 pacientes de este estudio fue de 73,7%. Se subraya que los adolescentes con rabdomiosarcoma admitidos al presente estudio presentaban enfermedad diseminada e histología de peor prognosis, contribuyendo al aumento en la tasa de mortalidad de este grupo de pacientes. CONCLUSIONES: Los adolescentes con cáncer corresponden a un grupo de pacientes que presenta características peculiares si comparados a otros grupos oncológicos. Hay diferencia histológica de los tumores de los adolescentes con los de la infancia, en que predominan leucemias y tumores del sistema nervioso central. En ese contexto, es fundamental facilitar el acceso de esos pacientes a centros especializados y ofrecer medios apropiados al diagnóstico temprano y tratamiento adecuado.OBJETIVO: Analisar as características epidemiológicas dos adolescentes portadores de neoplasias encaminhados para o Instituto de Oncologia Pediátrica (IOP/GRAACC) da Universidade Federal de São Paulo (UNIFESP), entre os anos de 2000 a 2006. MÉTODOS: Trata-se de um estudo retrospectivo descritivo, em que foram avaliados os dados epidemiológicos dos pacientes, com idade entre dez e19 anos ao diagnóstico, admitidos do ano 2000 a 2006 no IOP/Graacc. RESULTADOS: Do total de 2.362 pacientes admitidos neste período com diagnóstico de câncer, 629 (26,6%) eram adolescentes. A idade média encontrada foi de 13,8 anos, sendo a maioria do sexo masculino (56,8%). Em relação à raça, 60,7% dos pacientes eram brancos. Os tipos de tumores mais frequentes foram: tumores de sistema nervoso central (22,1%), osteossarcoma (14,6%), linfomas (14,5%) e leucemias (14,5%). A sobrevida global, em cinco anos, dos 629 pacientes deste estudo foi de 73,7%. Destaca-se que os adolescentes com rabdomiossarcoma apresentavam doença disseminada e histologia de pior prognóstico, contribuindo para o aumento na taxa de mortalidade deste grupo de pacientes. CONCLUSÕES: Os adolescentes com câncer correspondem a um grupo de pacientes que apresenta características peculiares quando comparado a outros grupos oncológicos. Há diferença histológica dos tumores dos adolescentes com os da infância, em que predominam leucemias e tumores do sistema nervoso central. Nesse contexto, é fundamental facilitar o acesso desses pacientes a centros especializados e oferecer meios apropriados para o diagnóstico precoce e tratamento adequado.Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM)UNIFESP Instituto de Oncologia Pediátrica Grupo de Apoio ao Adolescente e a Criança com CâncerUNIFESP, EPMUNIFESP, Instituto de Oncologia Pediátrica Grupo de Apoio ao Adolescente e a Criança com CâncerSciEL

Site localization of Cd impurities in sapphire

By combining first-principles electronic structure calculations and existing time-differential gamma-gamma perturbed-angular-correlation experiments we studied the site localization, the local environment, and the electronic structure of Cd impurities in sapphire (alpha-Al2O3) single crystals in different charged states. The ab initio calculations were performed with the full-potential augmented plane wave plus local orbitals method and the projector augmented wave method. Comparing the calculated electric-field-gradient tensor at the Cd nuclei in the alpha-Al2O3 host lattice and the corresponding available experimental values, we have seen that it is equally possible for Cd to replace an Al atom (in a negative charge state) or to be placed in an interstitial site (in a neutral charge state). To finally address the issue of the Cd impurity localization, we performed formation energy calculations. These results have shown that Cd placed in the substitutional Al site, in the negatively charged state, is the most probable configuration.Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET)Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) [PIP 0002]CNPqCNPqCAPESCAPESFAPESPFAPES

Spectroscopic characterization of schiff base-copper complexes immobilized in smectite clays

Herein, the immobilization of some Schiff base-copper(II) complexes in smectite clays is described as a strategy for the heterogenization of homogeneous catalysts. The obtained materials were characterized by spectroscopic techniques, mostly UV/Vis, EPR, XANES and luminescence spectroscopy. SWy-2 and synthetic Laponite clays were used for the immobilization of two different complexes that have previously shown catalytic activity in the dismutation of superoxide radicals, and disproportionation of hydrogen peroxide. The obtained results indicated the occurrence of an intriguing intramolecular redox process involving copper and the imine ligand at the surface of the clays. These studies are supported by computational calculations

First-principles studies of complex magnetism in Mn nanostructures on the Fe(001) surface

The magnetic properties of Mn nanostructures on the Fe(001) surface have been studied using the noncollinear first-principles real space-linear muffin-tin orbital-atomic sphere approximation method within density-functional theory. We have considered a variety of nanostructures such as adsorbed wires, pyramids, and flat and intermixed clusters of sizes varying from two to nine atoms. Our calculations of interatomic exchange interactions reveal the long-range nature of exchange interactions between Mn-Mn and Mn-Fe atoms. We have found that the strong dependence of these interactions on the local environment, the magnetic frustration, and the effect of spin-orbit coupling lead to the possibility of realizing complex noncollinear magnetic structures such as helical spin spiral and half-skyrmion.CNPqCNPqCAPESCAPESFAPESPFAPESPFAPESPA, BrazilFAPESPA, Brazi

In Silico insights on the electrode high sensitivity to salts.

Recent findings in sensing and biosensing based on electrical measurements\ud point to a very high sensitivity, in which the introduction of one molecule of\ud an analyte into one million (or more) molecules of water is already detectable.\ud In some cases, the high sensitivity could be attributed to specific interactions\ud between the analyte and the molecules on the sensing unit, but results have\ud also been published of considerable sensitivity of bare electrodes for\ud molecules with no molecular recognition capability. This is the case of\ud some electronic tongues reported in the literature. lt seems that the presence\ud of trace amounts of the analyte, e.g. a NaCl molecule, is sufficient to ai ter the\ud properties of the water at the interface, particularly because the electrical\ud measurements are very sensitive to interface changes.CAPESCNPqFAPESPNSF/US

Metal coordination study at Ag and Cd sites in crown thioether complexes through DFT calculations and hyperfine parameters

Structural and electronic properties of [C₁₂H₂₄S₆X], [C₁₃H₂₆S₆OX], and [C₁₄H₂₈S₆OX] (X: Ag⁺, Cd²⁺) crown thioether complexes were investigated within the framework of the density functional theory (DFT) using the projector augmented wave (PAW) method. The theoretical results were compared with time-differential perturbed γ-γ angular correlations (TDPAC) experiments reported in the literature using the ¹¹¹Ag→¹¹¹Cd probe. In the case of X=Ag⁺, a refinement of the structure was performed and the predicted equilibrium structures compared with available X-ray diffraction experimental data. Structural distortions induced by replacing Ag⁺ with Cd²⁺ were investigated as well as the electric-field gradient (EFG) tensor at the Cd²⁺ sites. Our results suggest that the EFG at Cd²⁺ sites corresponds to the Ag⁺ coordination sphere structure, i.e., before the structural relaxations of the molecule with X=Cd²⁺ are completed. The results are discussed in terms of the characteristics of the TDPAC ¹¹¹Ag→¹¹¹Cd probe and the time window of the measurement, and provide an interesting tool with which to probe molecular relaxations.Instituto de Física La Plat

Copper complex-DNA lnteractions: molecular simulations studies.

Previous studies on [Cu(isaepy)]+ have shown its potential antitumor activity\ud through preferential attack to DNA. The main target of this work is to build\ud molecular models of DNA-[Cu(isaepy)]+ and analyze it through state of the art\ud computational methodologies in order to obtain detailed structural and\ud dynamic information of these Cu complexes with potential pharmaceutical\ud and medicinal application. We are developing studies on the detection and\ud characterization of some Cu-oxindolimine complexes interactions with\ud biomolecules as DNA

Theoretical studies of Mefenamic Acid Polymorphs: Solid-state 13C carbon-NMR and vibrational (IR and Raman) Spectroscopies.

The two polymorphs of mefenamic acid (MEF) or 2-[(2,3-(dimethyphenyl)amino] benzoic acid polymorphs (known as I and II forms) were studies in the framkework of density functional theory (DFT). The DFT calculations were performed using the Gaussian03 package and these results were compared with experimental data of solid-state 13C Nuclear Magnetic Resonance (NMR), vibrational Raman and infrared spectroscopies.CAPESCNPqFAPES

Industrial scale isolation, structural and spectroscopic characterization of epiisopiloturine from Pilocarpus microphyllus stapf leaves: a promising alkaloid against schistosomiasis

This paper presents an industrial scale process for extraction, purification, and isolation of epiisopiloturine (EPI) (2(3H)- Furanone,dihydro-3-(hydroxyphenylmethyl)-4-[(1-methyl-1H-imidazol-4-yl)methyl]-, [3S-[3a(R*),4b]]), which is an alkaloid from jaborandi leaves (Pilocarpus microphyllus Stapf). Additionally for the first time a set of structural and spectroscopic techniques were used to characterize this alkaloid. EPI has shown schistomicidal activity against adults and young forms, as well as the reduction of the egg laying adult worms and low toxicity to mammalian cells (in vitro). At first, the extraction of EPI was done with toluene and methylene chloride to obtain a solution that was alkalinized with ammonium carbonate. The remaining solution was treated in sequence by acidification, filtration and alkalinization. These industrial procedures are necessary in order to remove impurities and subsequent application of the high performance liquid chromatography (HPLC). The HPLC was employed also to remove other alkaloids, to obtain EPI purity higher than 98%. The viability of the method was confirmed through HPLC and electrospray mass spectrometry, that yielded a pseudo molecular ion of m/z equal to 287.1 Da. EPI structure was characterized by single crystal X-ray diffraction (XRD), 1H and 13C nuclear magnetic resonance (NMR) in deuterated methanol/chloroform solution, vibrational spectroscopy and mass coupled thermal analyses. EPI molecule presents a parallel alignment of the benzene and the methyl imidazol ring separated by an interplanar spacing of 3.758 Å indicating a π-π bond interaction. The imidazole alkaloid melts at 225°C and decomposes above 230°C under air. EPI structure was used in theoretical Density Functional Theory calculations, considering the single crystal XRD data in order to simulate the NMR, infrared and Raman spectra of the molecule, and performs the signals attribution