Verres et vitroc��ramiques �� base de chalco: halog��nures dop��s par des ions de terres rares pour la luminescence dans le visible

P��s-gradua����o em Qu��mica - IQ

Laser emission of a Nd-doped mixed tellurite and zinc oxide glass

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Prepara����o pelo m��todo poliol modificado, caracteriza����o estrutural e espectrosc��pia de nanop��s de niobato de pot��ssio e neod��mio e de suas condi����es s��lidas dopadas em eur��pio

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Differentiation and species status of the Neotropical yellow-eared bats Vampyressa pusilla and V. thyone (Phyllostomidae) with a molecular phylogeny and review of the genus

A systematic re-evaluation of Vampyressa pusilla warrants the elevation of V. p. thyone from subspecies to species rank based on its distinction from the allopatric V. p. pusilla. Morphological, mensural, chromosomal, and mitochondrial differences define each of these two taxa as divergent lineages. Vampyressa pusilla is endemic to the Atlantic Forest of southeastern South America and V. thyone is found allopatrically in northwestern South America, Central America, and southern Mexico. A molecular phylogenetic analysis of the mtDNA ND3-4 gene region using restriction endonuclease cut sites resulted in a monophyletic, although weakly supported Vampyressa ingroup with Chiroderma, and a clade of Mesophylla and Ectophylla as successive basal outgroup lineages. The phylogeny within Vampyressa, with the exception of V. melissa which is most similar to V. thyone based on karyotypes and morphology, had a topology of ((pusilla + thyone) + ((brocki + nymphaea) + bidens))).

S��ntese, caracteriza����o e avalia����o da atividade biol��gica de metalof��rmacos de sulindaco com ��ons lantan��deos (III) no estado s��lido

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

S��ntese e caracteriza����o de sab��es met��licos de lantan��deos (III)

P��s-gradua����o em Qu��mica - IQ

Persistent luminescence mechanisms: human imagination at work

The present status and future progress of the mechanisms of persistent luminescence are critically treated with the present knowledge. The advantages to be achieved by a further need as well as the pitfalls of the excessive use of imagination are shown. As usual, in the beginning of the present era of persistent luminescence since the mid 1990s, the imagination played a more important role than the sparse solid experimental data and the chemical common sense and knowledge was largely ignored. Since some five years, the mechanistic studies seem to have reached the maturity and - perhaps deceivingly - it seems that there are only details to be solved. However, the development of red emitting nanocrystalline materials poses a challenge also to the more fundamental studies and interpretation. The questions still luring in the darkness include the problems how the increased surface area affects the defect structure and how the "persistent energy transfer" really works. There is still some light to be thrown onto these matters starting with agreeing on the terminology: the term phosphorescence should be abandoned altogether. The long lifetime of persistent luminescence is due to trapping of excitation energy, not to the forbidden nature of the luminescent transition. However, the technically well-suited term "afterglow" should be retained for harmful, short persistent luminescence. (C) 2012 Optical Society of America

Frequency upconversion properties of Tm3+ doped TeO2-ZnO glasses containing silver nanoparticles

Frequency upconversion (UC) properties of Tm3+ doped TeO2-ZnO glasses containing silver nanoparticles (NPs) were investigated. Infrared-to-visible and infrared-to-infrared UC processes associated to the Tm3+ ions were studied by exciting the samples with a cw 1050 nm ytterbium laser. The luminescence intensity as a function of laser intensity was also measured using a pulsed 1047 nm Nd3+:YVO laser in order to determine the number of photons participating in the UC processes. Enhancement of the UC signals for samples heat-treated during various time intervals is attributed to the growth of the local field in the vicinity of the NPs. PL enhancement by one-order of magnitude was observed in the whole spectrum of the samples heat-treated during 48 h. On the other hand PL quenching was observed for the samples heat-treated more than 48 h. (c) 2011 Elsevier B.V. All rights reserved.

Molecular plating of thin lanthanide layers with improved material properties for nuclear applications

In der vorliegenden Arbeit werden Experimente beschrieben, die zu einem vertieften Verst��ndnis fundamentaler Prozesse bei der elektrochemischen Herstellung von D��nnschichten, sog. Targets, f��r kernphysikalische und -chemische Studien f��hrten. Targets wurden mittels 'Molecular Plating' (MP) hergestellt, indem eine Elektrodeposition aus organischem Medium in der Regel bei konstantem Strom in Zwei-Elektroden-Zellen. Die Resultate erlaubten, optimierte Herstellungs-bedingungen zu ermitteln, welche die Produktion deutlich verbesserter Targets erlaubten. MP bei konstantem Strom ist ein massentransportkontrollierter Prozess. Der angelegte Strom wird durch einen konstanten Fluss elektroaktiver Spezies zur Kathode ��� auf der die Schicht w��chst ��� und Anode aufrechterhalten. Die Untersuchungen zeigten, dass das Zellenpotential des Elektrodepositionsystems immer durch den Ohm'schen Spannungsabfall auf Grund des Widerstandes der verwendeten L��sung dominiert wurde. Dies erlaubte die Herleitung einer Beziehung zwischen dem Zellenpotential und der Konzentration der elektroaktiven Spezies. Die Beziehung erlaubt die Erkl��rung des gemessenen zeitlichen Verlaufs des Zellenpotentials w��hrend der Abscheidung als Funktion der Elektrolytkonzentration. Dies dient als Basis, auf der nun ein umfassenderes Bild der Prozesse, die f��r die charakteristischen Minima im Potentialverlauf einer Abscheidung verantwortlich sind, gewonnen werden kann. Es konnte gezeigt werden, dass die Minima mit der fast vollst��ndigen Entfernung (durch Abscheidung) der aus einem gel��sten Salz erzeugten Nd-Ionen korrespondieren. Die abgeschiedene Spezies wurde als Nd3+ identifiziert, vermutlich als Carboxylat, Oxid oder Hydroxid, was auf Grund der hohen negative Werte des Standardredoxpotentials der Lanthanide verst��ndlich erscheint. Von den vorliegenden elektroaktiven Spezies tragen die Nd3+ Ionen nur zu knapp 20% zum Gesamtstrom bei. Durch Elektrolyse tragen auch die L��sungsmittelkomponenten zu diese Strom bei. Die Gegenwart von elektrolysiertem L��sungsmittel wurde in Analysen der D��nnschichten best��tigt. Diese waren immer mit chemi- und physisorbierten L��sungsmittelmolek��len bedeckt. Die Analyse der D��nnschichten zeigte, dass die Oberfl��chen von einem furchenartiges Netz durchzogen waren, und dass diese w��hrend des Trocknen der Schichten nach dem MP entstanden. Ob die Schichten an Luft oder in inerter Atmosph��re trockneten, hatte keinen Einfluss. Es wurden Experimente mit mehreren L��sungsmitteln durchgef��hrt, die sich deutlich in ihren physikalischen Eigenschaften, v.a. dem Siedepunkt, unterschieden. Furchenfreie D��nnschichten konnten insbesondere bei MP in N,N-dimethylformamide (DMF) erzeugt werden. Die Verwendung von DMF in Kombination mit einer Abscheidung auf sehr glatten Substraten erlaubte die Produktion von sehr homogenen, glatten und defektfreien Schichten. Diese waren vermutlich geringeren inneren Spannungen w��hrend des Trocknens ausgesetzt, als Schichten auf raueren Substraten oder solche, die aus fl��chtigeren L��sungsmitteln hergestellt wurden. Die Oberfl��chenrauigkeit des Substrats und das gew��hlte L��sungsmittel wurden so als Schl��sselfaktoren f��r die Produktion hochqualitativer Schichten identifiziert. Es konnte gezeigt werden, dass mit MP eine sehr effiziente Methode zur Herstellung homogener Schichten mit exzellenter Ausbeute ist. In weiteren Experimenten mit dem primordialen Alpha-Emitter 147Sm als Modellisotop wurde die Eignung solcher Schichten als Alpha-Quelle untersucht. Sowohl die Energieaufl��sung als auch der Anteil der Alpha-Teilchen, die den Detektor erreichten, waren von den Quelleneigenschaften abh��ngig. Die Effekte wurden verschiedenen Variablen der D��nnschicht zugeordnet, welche die Alpha-Spektren beeinflussten. Dominant war die Wahl des L��sungsmittels und die Rauigkeit des Substrats. Dies beeinflusste Schichtdicke und -morphologie sowie die Art des Schichtwachstums und ver��nderte die Detektionseffizienz in Alpha-Messungen bis zu 15%. Nur homogene, ebene Schichten, die aus DMF auf glatten Substraten abgeschieden wurden, eignen sich optimal als Alpha-Quelle. Die gewonnenen Ergebnisse erlauben die optimierte Herstellung nuklearer Targets durch MP. K��nftige Anwendungen beinhalten insbesondere die Herstellung von Targets f��r neutroneninduzierte Spaltexperimente und untergrundarme���Alpha-Messungen sehr kleiner Aktivit��ten.

Broadband emission from a multicore fiber fabricated with granulated oxides

We demonstrate a multicore multidopant fiber which, when pumped with a single pump source around ���800���nm , emits a more than one octave-spanning fluorescence spectrum ranging from 925 to 2300���nm . The fiber preform is manufactured from granulated oxides and the individual cores are doped with five different rare earths, i.e., Nd3+ , Yb3+ , Er3+ , Ho3+ , and Tm3+ .

Microfabrication processes for microfluidic devices on a single laser Workstation: direct writing lithography on SU-8, laser ablation on polymers and mask manufacturing

We demonstrate the capability of a laser micromachining workstation for cost-effective manufacturing of a variety of microfluidic devices, including SU-8 microchannels on silicon wafers and 3D complex structures made on polyimide Kapton�� or poly carbonate (PC). The workstation combines a KrF excimer laser at 248 nm and a Nd3+:YVO4 DPSS with a frequency tripled at 355 nm with a lens magnification 10X, both lasers working at a pulsed regime with nanoseconds (ns) pulse duration. Workstation also includes a high-resolution motorized XYZ-tilt axis (~ 1 um / axis) and a Through The Lens (TTL) imaging system for a high accurate positioning over a 120 x 120 mm working area. We have surveyed different fabrication techniques: direct writing lithography,mask manufacturing for contact lithography and polymer laser ablation for complex 3D devices, achieving width channels down to 13�� m on 50�� m SU-8 thickness using direct writing lithography, and width channels of 40 ��m for polyimide on SiO2 plate. Finally, we have tested the use of some devices for capillary chips measuring the flow speed for liquids with different viscosities. As a result, we have characterized the presence of liquid in the channel by interferometric microscopy.

Complete mitochondrial genome suggests diapsid affinities of turtles

Despite more than a century of debate, the evolutionary position of turtles (Testudines) relative to other amniotes (reptiles, birds, and mammals) remains uncertain. One of the major impediments to resolving this important evolutionary problem is the highly distinctive and enigmatic morphology of turtles that led to their traditional placement apart from diapsid reptiles as sole descendants of presumably primitive anapsid reptiles. To address this question, the complete (16,787-bp) mitochondrial genome sequence of the African side-necked turtle (Pelomedusa subrufa) was determined. This molecule contains several unusual features: a (TA)n microsatellite in the control region, the absence of an origin of replication for the light strand in the WANCY region of five tRNA genes, an unusually long noncoding region separating the ND5 and ND6 genes, an overlap between ATPase 6 and COIII genes, and the existence of extra nucleotides in ND3 and ND4L putative ORFs. Phylogenetic analyses of the complete mitochondrial genome sequences supported the placement of turtles as the sister group of an alligator and chicken (Archosauria) clade. This result clearly rejects the Haematothermia hypothesis (a sister-group relationship between mammals and birds), as well as rejecting the placement of turtles as the most basal living amniotes. Moreover, evidence from both complete mitochondrial rRNA genes supports a sister-group relationship of turtles to Archosauria to the exclusion of Lepidosauria (tuatara, snakes, and lizards). These results challenge the classic view of turtles as the only survivors of primary anapsid reptiles and imply that turtles might have secondarily lost their skull fenestration.

Two mitochondrial group I introns in a metazoan, the sea anemone Metridium senile: one intron contains genes for subunits 1 and 3 of NADH dehydrogenase.

Mitochondrial genes for cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 5 (ND5) of the sea anemone Metridium senile (phylum Cnidaria) each contain a group I intron. This is in contrast to the reported absence of introns in all other metazoan mtDNAs so far examined. The ND5 intron is unusual in that it ends with A and contains two genes (ND1 and ND3) encoding additional subunits of NADH dehydrogenase. Correctly excised ND5 introns are not circularized but are precisely cleaved near their 3' ends and polyadenylylated to provide bicistronic transcripts of ND1 and ND3. COI introns, which encode a putative homing endonuclease, circularize, but in a way that retains the entire genome-encoded intron sequence (other group I introns are circularized with loss of a short segment of the intron 5' end). Introns were detected in the COI and ND5 genes of other sea anemones, but not in the COI and ND5 genes of other cnidarians. This suggests that the sea anemone mitochondrial introns may have been acquired relatively recently.

NOx storage and reduction over copper-based catalysts. Part 2: Ce0.8M0.2O�� supports (M = Zr, La, Ce, Pr or Nd)

5% copper catalysts with Ce0.8M0.2O�� supports (M = Zr, La, Ce, Pr or Nd) have been studied by rapid-scan operando DRIFTS for NOx Storage and Reduction (NSR) with high frequency (30 s) CO, H2 and 50%CO + 50%H2 micropulses. In the absence of reductant pulses, below 200���250 ��C NOx was stored on the catalysts as nitrite and nitro groups, and above this temperature nitrates were the main species identified. The thermal stability of the NOx species stored on the catalysts depended on the acid/basic character of the dopant (M more acidic = NOx stored less stable ��� Zr4+ < none < Nd3+ < Pr3+ < La3+ ��� M more basic = NOx stored more stable). Catalysts regeneration was more efficient with H2 than with CO, and the CO + H2 mixture presented an intermediate behavior, but with smaller differences among the series of catalyst than observed using CO alone. N2 is the main NOx reduction product upon H2 regeneration. The highest NOx removal in NSR experiments performed at 400 ��C with CO + H2 pulses was achieved with the catalyst with the most basic dopant (CuO/Ce0.8La0.2O��) while the poorest performing catalyst was that with the most acidic dopant (CuO/Ce0.8Zr0.2O��). The poor performance of CuO/Ce0.8Zr0.2O�� in NSR experiments with CO pulses was attributed to its lower oxidation capacity compared to the other catalysts.