In order to study the influence of the insulator layer thickness in heterojunctions, (YBa2Cu3O7-δ[20nm]/ PrBa2Cu3Oy/La1/3Ca2/3MnO3[20nm])x20 superlattices were prepared by pulsed laser deposition using three PrBa2Cu3Oy layer thicknesses and two different sequences of deposition. Sample characterization showed primitive orthorhombic crystalline arrangement for YBCO and LCMO, however, a slightly disordered crystalline structure was observed for the sample having thicker PBCO layer. Microscopy analyses indicated influence of both parameters (PBCO thickness and sequence of deposition) on the texture of the upper layer. Electrostatic Force Microscopy analyses showed evident contrast on the phase images, what suggests that samples are conductive. Distinct surface aspect and highest contrast (highest shift in the electric mode phase image) were observed for the surface of the sample in which the sequence of deposition was inverted, with the YBCO ceramic as upper layer of the superlattice.

The use of residues, in partial or total substitution of aggregates or binders in concrete, presents interesting possibilities for obtaining eco-efficient concretes. Research has investigated the use of glass residue in Portland cement composite, whether as an aggregate or a supplementary cementitious material. However, there is still no consensus on the influence of the chemical composition of glass on the behaviour of the composites in which it is used. This paper analyse the influence of this composition on the performance of cement composites produced with microparticles of colourless and amber glass. Pozzolanicity was assessed by direct (Modified Chapelle, electrical conductivity) and indirect test (chemical characterization, X-ray diffraction, thermogravimetric analysis, differential thermal analysis and Strength Activity Index testing. The results show that microparticles of both glass display pozzolanic activity, with no significant differences between them. This confirms the potential for the use of glass microparticles as a supplementary material in cement composites.

The synthesis of magnetic materials such as nanostructured iron oxide has been intensively researched due to their broad applications in biomedicine. As these nanoparticles have high specific surface area, they are very reactive and can aggregate easily, and biodegrade when exposed to biological systems. Mesoporous silica is often employed as support matrix to protect the magnetic functional component, avoiding undesirable effects. In this context, this review describes various syntheses of silica-coated iron oxide nanoparticles, and their use in applications such as bioseparation, magnetic resonance imaging, hyperthermia and drug delivery systems showing the growing interest of these materials in biological area.

OBJETIVO: o presente trabalho teve como finalidade avaliar clinicamente uma nova alternativa mecânica para a erupção guiada ao plano oclusal de um dente pré-molar impactado empregando magnetos atrativos da liga samário-cobalto. METODOLOGIA: o tratamento cirúrgico-ortodôntico foi realizado em uma paciente jovem de 11 anos portadora de oclusão de Classe I de Angle, com impactação do segundo pré-molar inferior direito. O sistema magnético empregado consistiu de um magneto colado com resina fotopolimerizável sobre a superfície vestibular do dente impactado e um outro pólo magnético rígido incrustado em um aparelho banda alça. Previamente à instalação do sistema magnético no meio bucal, os magnetos foram caracterizados através de análise de fluorescência, difração de raios X e nível de magnetização. A relação força/distância empregada foi quantificada, os magnetos foram medidos e a geometria magnética bucal estabelecida. RESULTADOS: o tempo empregado na desimpactação foi de 40 dias e foram necessárias duas ativações magnéticas por aproximação dos magnetos neste intervalo. A opção magnética neste caso clínico foi bastante eficaz tanto em relação ao tempo de tratamento quanto em relação ao conforto proporcionado ao paciente. Os magnetos empregados geraram um campo de força contínuo e autônomo não sendo necessária a utilização de fios metálicos como guias de orientação na erupção e nem elásticos de tracionamento. CONCLUSÃO: esta possibilidade terapêutica poderá ser útil em desimpactações mais profundas tais como os caninos ectópicos, cuja ocorrência é freqüente.

AIM: the present work evaluated a new mechanical alternative to guide the eruption to the oclusal plan of a impacted bicuspid tooth using attractive cobalt-samarium magnets. METHODS: the treatment was accomplished in a 11 years old Class I young patient, with a impacted right inferior second premolar. The magnetic system consisted of magnets bonded to the vestibular surface of the impacted tooth and a rigid magnetic pole incrusted in a band and loop container. Previously to the installation of the magnetic system, the magnets were characterized through fluorescence analysis, X rays diffraction and magnetization level. The force/distance relationship used was quantified, the magnets were measured and the buccal magnetic geometry established. RESULTS: the time used in the desimpactation was of 40 days and were necessary two magnetic activations to approach the magnets in this interval. The magnetic option in this clinical case was quite effective so much in relation to the time of treatment as in regard to the comfort proportionated to the patient. The magnets generated a continuous and autonomous force field, not being necessary to use metallic threads as orientation guides in the eruption and nor elastic. CONCLUSION: this therapeutic possibility will frequently be useful in such deeper desimpactation as the canine teeth ectopics, seen in the daily activity.

In this work highly dispersed Ru-Sn bimetallic catalysts have been prepared from organobimetallic Cp(PPh3)2Ru-SnX3 (X = Cl or Br) complexes. These single source precursors can be easily impregnated in high surface area supports, such as activated carbon and sol-gel SiO2, and upon controlled thermal treatment the ligands are released as volatile products resulting in the formation of the bimetallic system Ru-Sn. Catalytic reactions, such as hydrodechlorination of CCl4 and chlorobenzene and TPR (Temperature Programmed Reduction) experiments carried out with these RuSn catalysts suggested a strong interaction between Ruthenium and Tin. Mössbauer measurements showed that these materials when exposed to air are immediately oxidized to form Sn (IV). It was shown that upon controlled reduction conditions with H2 it is possible to reduce selectively Sn to different oxidation states and different phases. The Sn oxidation state showed significant effect on the catalytic hydrogenation of 1,5-cyclooctadiene. The use of these single source precursors with a controlled decomposition/reduction procedure allows the preparation of unique catalysts with an intimate interaction between the components ruthenium and tin and the possibility of varying the Sn oxidation state around the Ru metal.

The preparation of gamma-LiAlO2 by coprecipitation and sol-gel synthesis was investigated. Ceramic powders obtained by coprecipitation synthesis were prepared from aqueous solutions of aluminum and lithium nitrates using sodium hydroxide as precipitant agent. By sol-gel synthesis, the ceramic powders were prepared from hydrolysis of aluminum isopropoxide. The materials obtained by two routes of synthesis were dried at 80ºC and calcined at 550, 750, 950 and 1150ºC. The characterization was done by X-ray diffraction, infrared spectroscopy, emission and absorption atomic spectrometry, helium picnometry, specific surface area (BET method) and scanning electronic microscopy. Mixtures of crystalline phases were obtained by coprecipitation synthesis: 80ºC- LiAl2(OH)7.2H2O + Al(OH)3; 550 and 750ºC- alpha-LiAlO2 + eta-Al2O3; 950 and 1150ºC- gamma-LiAlO2 + LiAl5O8. Chemical analysis showed molar ration Al/Li <FONT FACE=Symbol>@</FONT> 3. Crystalline single-phases were obtained by sol-gel synthesis above 550ºC: 550ºC-alpha-LiAlO2; 750, 950 and 1150ºC-gamma-LiAlO2. These powders presented molar ration Al/Li <FONT FACE=Symbol>@</FONT> 1. Thus, gamma-LiAlO2 crystalline phase was obtained at 750ºC by sol-gel synthesis while by coprecipitation synthesis, a mixture of crystalline phases was obtained. These results showed the superiority of the sol-gel synthesis for the preparation of pure gamma-LiAlO2.