One-Pot, Three-Step Reaction of 5-[(Trimethylsilyl)ethynyl]pyrrolidin-2-one with Azides Catalyzed by Cu-I: Synthesis of a Novel Class of 1,4-Disubstituted 1,2,3-Triazoles

A very fast, easy and efficient synthesis is described for a novel and biologically important class of 1,4-disubstituted-4-(5-pyrrolidin-2-one)-1,2,3-triazoles by an ultrasound-assisted one-pot, three-step click reaction sequence of 5-[(trimethylsilyl)ethynyl]pyrrolidin-2-one with organic azides mediated by catalytic Cu-I salts.

Cu(GlyGlyHis) effects on MCF7 cells: Copper uptake, reactive oxygen species generation and membrane topography changes

Elevated levels of copper have been detected in various types of human cancer cells, such as breast cancer cells, and a number of mechanisms have been proposed to explain the action and influence of copper on tumor progress. In this work, we found that stimulating the proliferation of mammary epithelial MCF7 cells with the high-redox-potential copper complex Cu (GlyGlyHis) is associated with the copper-induced intracellular generation of reactive oxygen species (ROS) that induces lipid peroxidation and causes increased roughness of external cell membranes, which leads to the formation of larger cell domes. The results presented herein provide new insights into the molecular link between copper and the proliferation of breast cancer cells and, consequently, into the mechanism by which changes in redox balance and ROS accumulation regulates cell membrane roughness. (C) 2012 Elsevier Inc. All rights reserved.

Evaluation of Inductively Coupled Plasma Mass Spectrometry for Determining Ca, Cu, Fe, Mg, Mn, Se and Zn in Bovine Semen Samples using a Simple Sample Dilution Method

A simple and fast method for the determination of Ca, Cu, Fe, Mg, Mn, Se and Zn in bovine semen by quadrupole inductively coupled plasma spectrometry (q-ICP-MS) is described. Prior to analysis, samples (200 mu L) were diluted 1:50 in a solution containing 0.01% v/v Triton (R) X-100 and 0.5% v/v nitric acid and directly analyzed by ICP-MS. The limits of detection of the method are 0.3, 0.03, 0.2, 0.04, 0.04, 0.03 and 0.03 mu g L-1 for Ca-44, Cu-63, Fe-57, Mg-24, Zn-64, Se-82 and Mn-55, respectively. For purposes of comparison and method validation, four ordinary bovine semen samples were directly analyzed by ICP-MS and by flame atomic absorption spectrometry (FAAS) or graphite furnace atomic absorption spectrometry (GF AAS), with no statistical difference between the techniques at the 95% level when applying the t-test. Then, the proposed method was applied in the determinations of Ca, Cu, Fe, Mg, Mn, Se and Zn in collected samples of bovine semen from different breeds, which are used in reproduction programs and artificial insemination.

Evaluation of inductively coupled plasma mass spectrometry for determining Ca, Cu, Fe, Mg, Mn, Se and Zn in bovine semen samples using a simple sample dilution method

A simple and fast method for the determination of Ca, Cu, Fe, Mg, Mn, Se and Zn in bovine semen by quadrupole inductively coupled plasma spectrometry (q-ICP-MS) is described. Prior to analysis, samples (200 µL) were diluted 1:50 in a solution containing 0.01% v/v Triton® X-100 and 0.5% v/v nitric acid and directly analyzed by ICP-MS. The limits of detection of the method are 0.3, 0.03, 0.2, 0.04, 0.04, 0.03 and 0.03 µg L-1 for 44Ca, 63Cu, 57Fe, 24Mg, 64Zn, 82Se and 55Mn, respectively. For purposes of comparison and method validation, four ordinary bovine semen samples were directly analyzed by ICP-MS and by flame atomic absorption spectrometry (FAAS) or graphite furnace atomic absorption spectrometry (GF AAS), with no statistical difference between the techniques at the 95% level when applying the t-test. Then, the proposed method was applied in the determinations of Ca, Cu, Fe, Mg, Mn, Se and Zn in collected samples of bovine semen from different breeds, which are used in reproduction programs and artificial insemination.

A importância da observação do céu no cotidiano escolar: o ponto de vista do professor.

A observação do céu pode promover diversos desenvolvimentos em um sujeito, ligados a aspectos culturais, tecnológicos e/ou pessoais, e por isso, pode ter um forte potencial motivador. Está proposto nos documentos oficiais, que regem os currículos da educação básica brasileira, que o professor realize atividades de observação e reconhecimento do céu, visando a trabalhar com a capacidade de analisar e interpretar fenômenos naturais do ponto de vista da ciência. Visando, então, a formar um professor que possa levar essa parte da astronomia para sala de aula, indo além do encantamento, o Grupo de Astronomia Sputnik promoveu um curso de curta duração, que dentre diversas atividades, visitou um observatório astronômico, com a intenção de fazer uma observação do céu e capacitar o professor para tal. Esta pesquisa apresenta algumas das concepções desses professores sobre qual a importância da observação do céu tanto para o ensino de astronomia quanto para sua própria formação profissional. Os resultados apontam que, pelo fato dos próprios professores se sentirem bastante motivados com a atividade, eles reconhecem esse potencial para a sala de aula. Do ponto de vista de conteúdos que podem ser veiculados, aparecem alguns em algumas falas, mas ainda é forte a ideia de que para ocorrência desse tipo de atividade prática é preciso que ela esteja vinculada e complementando alguma teoria.

First principles calculations for vacancies and antisites in PbSe and PbTe: bulk and nanowire.

The energetic stability and the electronic properties of vacancies (VX) and antisites (XY) in PbSe and PbTe are investigated. PbSe and PbTe are narrow band gap semiconductors and have the potential to be used in infrared detectors, laser, and diodes. They are also of special interest for thermoelectric devices (TE). The calculations are based in the Density Functional Theory (DFT) and the General Gradient Approximation (GGA) for the exchange-correlation term, as implemented in the VASP code. The core and valence electrons are described by the Projected Augmented Wave (PAW) and the Plane Wave (PW) methods, respectively. The defects are studied in the bulk and nanowire (NW) system. Our results show that intrinsec defects (vacancies and antisites) in PbTe have lower formation energies in the NW as compared to the bulk and present a trend in migrate to the surface of the NW. For the PbSe we obtain similar results when compare the formation energy for the bulk and NW. However, the Pb vacancy and the antisites are more stable in the core of the NW. The intrinsec defects are shallow defects for the bulk system. For both PbSe and PbTe VPb is a shallow acceptor defect and VSe and VT e are shallow donor defects for the PbSe and PbTe, respectively. Similar electronic properties are observed for the antisites. For the Pb in the anion site we obtain an n-type semiconductor for both PbSe and PbTe, SeP b is a p-type for the PbSe, and T eP b is a n-type for PbTe. Due the quantum con¯nement effects present in the NW (the band gap open), these defects have different electronic properties for the NW as compared to the bulk. Now these defects give rise to electronic levels in the band gap of the PbTe NW and the VT e present a metallic character. For the PbSe NW a p-type and a n-type semiconductor is obtained for the VP b and P bSe, respectively. On the other hand, deep electronic levels are present in the band gap for the VSe and SePb. These results show that due an enhanced in the electronic density of states (DOS) near the Fermi energy, the defective PbSe and PbTe are candidates for efficient TE devices.

Oxidación de Cu(I) en agua de mar

La cinética de oxidación de Cu(I) con oxígeno, a concentración nanomolar, se ha estudiado en función de la concentración de cobre (I), pH, concentración de bicarbonato y de la temperatura, al objeto de obtener las ecuaciones de dependencia de la constante de velocidad con cada variable, en NaCl (0.7M) con bicarbonato (2mM) y en agua de mar. Los estudios a escala nanomolar se han comparado con los estudios realizados por otros autores a escala micromolar. El tiempo de vida medio a nivel nanomolar es superior en ambos medios, lo que justifica la presencia de concentraciones medibles de Cu(I) en aguas superficiales. La constante de velocidad de segundo orden (k) es independiente de la concentración de Cu(I), en el rango de 20 a 200 nM, con lo que los resultados permiten una visión más realista de lo que ocurre en el océano. En los estudios del efecto del pH en la cinética de oxidación se obtienen rectas próximas para disolución de NaCl (0.7M) con bicarbonato (2mM) y en agua de mar, por lo que las interacciones específicas pueden despreciarse o quedar compensadas entre sí. La ecuación obtenida para cada caso es: Logk(NaCl) = −2.453(±0.341) + 0.611(±0.044)pH (para NaCl) Logk(sw) = −1.484(±0.266) + 0.489(±0.034) pH (para agua de mar) La concentración de bicarbonato produce un aumento en la constante de segundo orden (k) hasta 5mM, comportándose de acuerdo con la ecuación siguiente: [ ] [ ]2 3 2 3 3 2 2 ( ) 1.54 10 ( 3.518 10 ) 3.963( 58.17 10 ) 0.212( 3.242 10 ) 3 NaHCO Logk NaHCO NaHCO − − − ⋅ ± ⋅ = − ± ⋅ + ± ⋅ − El aumento de la temperatura produce un aumento en la constante de velocidad relacionándose este efecto con la entalpía y entropía de activación del proceso. Oxidación de Cu(I) en agua de mar 8 El trabajo realizado supone un mejor conocimiento de los procesos que controlan la cinética de oxidación del Cu(I) en medios naturales y servirán de base para futuros experimentos.

Paralelización de un algoritmo de ray tracing para arrays de mililentes

Máster Universitario en Sistemas Inteligentes y Aplicaciones Numéricas en Ingeniería (SIANI)

Atmospheric corrosion of quaternary bronzes (Cu-Sn-Zn-Pb): laboratory tests (accelerated ageing in wet & dry conditions)and field studies (the Bottego monument in Parma, Italy).

The interactions between outdoor bronzes and the environment, which lead to bronze corrosion, require a better understanding in order to design effective conservation strategies in the Cultural Heritage field. In the present work, investigations on real patinas of the outdoor monument to Vittorio Bottego (Parma, Italy) and laboratory studies on accelerated corrosion testing of inhibited (by silane-based films, with and without ceria nanoparticles) and non-inhibited quaternary bronzes are reported and discussed. In particular, a wet&dry ageing method was used both for testing the efficiency of the inhibitor and for patinating bronze coupons before applying the inhibitor. A wide range of spectroscopic techniques has been used, for characterizing the core metal (SEM+EDS, XRF, AAS), the corroded surfaces (SEM+EDS, portable XRF, micro-Raman, ATR-IR, Py-GC-MS) and the ageing solutions (AAS). The main conclusions were: 1. The investigations on the Bottego monument confirmed the differentiation of the corrosion products as a function of the exposure geometry, already observed in previous works, further highlighting the need to take into account the different surface features when selecting conservation procedures such as the application of inhibitors (i.e. the relative Sn enrichment in unsheltered areas requires inhibitors which effectively interact not only with Cu but also with Sn). 2. The ageing (pre-patination) cycle on coupons was able to reproduce the relative Sn enrichment that actually happens in real patinated surfaces, making the bronze specimens representative of the real support for bronze inhibitors. 3. The non-toxic silane-based inhibitors display a good protective efficiency towards pre-patinated surfaces, differently from other widely used inhibitors such as benzotriazole (BTA) and its derivatives. 4. The 3-mercapto-propyl-trimethoxy-silane (PropS-SH) additivated with CeO2 nanoparticles generally offered a better corrosion protection than PropS-SH.

Sintesi di catalizzatori supportati Au/Cu e studio della loro reattività per l'ossidazione selettiva del 5-idrossimetilfurfurale

Al giorno d’oggi i combustibili fossili come carbone, olio e gas naturale forniscono più del 75% dell’energia mondiale. Tuttavia, la crescente richiesta di queste fonti di energia non rinnovabili, si manifesta in un momento in cui le riserve naturali si stanno esaurendo; è stato infatti stimato che le riserve petrolifere di tutto il mondo possano essere sufficienti per fornire energia e produrre prodotti chimici per i prossimi quarant’anni. Per questo motivo la conversione delle biomasse per produrre energia e prodotti chimici sta diventando una valida alternativa per diversificare le fonti energetiche e ridurre il surriscaldamento globale. Le biomasse, infatti, oltre ad essere una fonte rinnovabile, generano minori emissioni di gas serra rispetto ai combustibili fossili, perché la CO2 rilasciata nei processi di utilizzo viene bilanciata da quella consumata nel processo di crescita delle biomasse stesse. Lo sfruttamento delle biomasse per la produzione di building blocks per la chimica suscita particolare interesse, poiché le molecole ottenute sono già parzialmente funzionalizzate; ciò significa che la sintesi di prodotti chimici specifici richiede un minor numero di stadi rispetto ai building blocks petroliferi, con conseguente diminuzione di prodotti di scarto e sottoprodotti. Un esempio di queste potenziali “molecole piattaforma” è il 5-idrossimetilfurfurale (HMF), un importante composto derivato dalla disidratazione di zuccheri, intermedio chiave per la sintesi di un’ampia varietà di prodotti chimici e combustibili alternativi, tra cui l’acido 2,5- furandicarbossilico (FDCA), che è stato identificato tra i dodici composti chimici più importanti degli ultimi anni. Per esempio, il FDCA è un possibile sostituto dell’acido tereftalico, usato per produrre il polietilentereftalato (PET). Recentemente alcuni autori hanno riportato interessanti risultati sull’ossidazione dell’HMF a FDCA utilizzando catalizzatori a base di Au supportato. Questi catalizzatori mostrano però significativi problemi di disattivazione. Lo scopo di questo lavoro di tesi è stato quindi lo sviluppo di catalizzatori attivi e stabili nella reazione di ossidazione dell’HMF a FDCA. Il lavoro portato avanti ha avuto come obbiettivi principali: l’ottimizzazione della sintesi di nanoparticelle di oro e oro/rame a diverso rapporto molare, mediante un processo di sintesi, in acqua, a basso impatto ambientale. Tale metodo di sintesi si basa sull’azione riducente del sistema glucosio-NaOH ed è stato messo a punto in lavori di tesi precedenti. Le nanoparticelle sintetizzate sono state utilizzate, quali fase attiva, per la preparazione di catalizzatori supportati su TiO2 e CeO2 lo studio dell’attività catalitica e riusabilità dei catalizzatori preparati nell’ossidazione in fase liquida del HMF a FDCA.