Surface characterization

The biocompatibility of commercially pure titanium and its alloys is closely related to their surface properties, with both the composition of the protecting oxide film and the surface topography playing an important role. Surfaces of commercially pure titanium and of the two alloys Ti-6Al-7Nb and Ti-6Al-4V (wt %) have been investigated following three different pretreatments: polishing, nitric acid passivation and pickling in nitric acid-hydrogen fluoride. Nitric acid treatment is found to substantially reduce the concentration of surface contaminants present after polishing. The natural 4-6 nm thick oxide layer on commercially pure titanium is composed of titanium oxide in different oxidation states (TiO2, Ti2O3 and TiO), while for the alloys, aluminium and niobium or vanadium are additionally present in oxidized form (Al2O3, Nb2O5 or V-oxides). The concentrations of the alloying elements at the surface are shown to be strongly dependent on the pretreatment process. While pickling increases the surface roughness of both commercially pure titanium and the alloys, different mechanisms appear to be involved. In the case of commercially pure titanium, the dissolution rate depends on grain orientation, whereas in the case of the two alloys, selective α-phase dissolution and enrichment of the β-phase appears to occur. © 1999 Kluwer Academic Publisher

Polymeric Photoacids Based on Naphthols—Design Criteria, Photostability, and Light-Mediated Release

The implementation of photoswitches within polymers offers an exciting toolbox in the design of light-responsive materials as irradiation can be controlled both spatially and temporally. Herein, we introduce a range of water-soluble copolymers featuring naphthol-based chromophores as photoacids in the side chain. With that, the resulting materials experience a drastic increase in acidity upon stimulation with UV light and we systematically studied how structure and distance of the photoacid from the copolymer backbone determines polymerizability, photo-response, and photostability. Briefly, we used RAFT (reversible addition–fragmentation chain transfer) polymerization to prepare copolymers consisting of nona(ethylene glycol) methyl ether methacrylate (MEO9MA) as water-soluble comonomer in combination with six different 1-naphthol-based (“N”) monomers. Thereby, we distinguish between methacrylates (NMA, NOeMA), methacrylamides (NMAm, NOeMAm), vinyl naphthol (VN), and post-polymerization modification based on [(1-hydroxynaphthalen-2-amido)ethyl]amine (NOeMAm, NAmeMAm). These P(MEO9MAx-co-“N”y) copolymers typically feature a 4:1 MEO9MA to “N” ratio and molar masses in the range of 10 kg mol−1. After synthesis and characterization by using NMR spectroscopy and size exclusion chromatography (SEC), we investigated how potential photo-cleavage or photo-degradation during irradiation depends on the type and distance of the linker to the copolymeric backbone and whether reversible excited state proton transfer (ESPT) occurs under these conditions. In our opinion, such materials will be strong assets as light-mediated proton sources in nanostructured environments, for example, for the site-specific creation of proton gradients. We therefore exemplarily incorporated NMA into an amphiphilic block copolymer and could demonstrate the light-mediated release of Nile red from micelles formed in water as selective solvent. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

The implant material, Ti6Al7Nb: surface microstructure, composition and properties

The excellent biocompatibility of titanium and its alloys is intimately related with the properties of the surface in contact with the biological environment, and therefore it is closely connected with the stable, passivating oxide layer that forms on its surface. In the present paper, the oxide layer on the alloy Ti6Al7Nb has been characterized using X-ray photoelectron spectroscopy, scanning Auger microscopy and pH-dependent lateral force microscopy. The alloying elements Al and Nb are incorporated in the oxide layer and detected in their most stable oxidized form, as Al2O3 and Nb2O5. Their distribution in the oxide reflects the underlying α-β microstructure, with enrichment of Al in the α- and of Nb in the β-phase (determined by electron microprobe). Friction measurements (lateral force microscopy) indicate slightly different, pH-dependent, lateral forces above the α- and β-phase structures that point to small local variations in surface charges. © 1999 Kluwer Academic Publisher

Quinoline Photobasicity: Investigation within Water-Soluble Light-Responsive Copolymers

Quinoline photobases exhibit a distinctly higher pKa in their electronically excited state than in the ground state, thereby enabling light-controlled proton transfer reactions, for example, in molecular catalysis. The absorption of UV light translates to a pKa jump of approximately 10 units, as established for small-molecule photobases. This contribution presents the first synthesis of quinoline-based polymeric photobases prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization. The integration of quinolines as photobase chromophores within copolymers offers new possibilities for light-triggered proton transfer in nanostructured materials, that is, in nanoparticles, at surfaces, membranes and interfaces. To exploit the light-triggered reactivity of photobases within such materials, we first investigated how the ground- and excited-state properties of the quinoline unit changes upon polymer integration. To address this matter, we combined absorption and emission spectroscopy with time-resolved transient-absorption studies to reveal photoinduced proton-transfer dynamics in various solvents. The results yield important insights into the thermodynamic and kinetic properties of these polymeric quinoline photobases. © 2020 The Authors. Chemistry - A European Journal published by Wiley-VCH Gmb

Музыкальный информационный поиск с запросом по напеву

In this paper the problems of Query by Humming in Music Information Retrieval systems are analyzed. A statistical approach to the problem of retrieval is presented. The processes of segmentation as well as of the extraction of pitch and duration data are described. From the extracted data the characteristic vector is formed for each segment. The method of using the vectors in melodic search if proposed

Evidência de acesso lexical não seletivo em crianças de uma escola bilíngue português-inglês

The issue of language selectivity regarding lexical access of bilingual adults has been thoroughly reported in the literature. However, studies with bilingual children are still limited, especially in the Brazilian context, where the number of bilingual schools has been increasing rapidly in the last few years. To fill this gap, the present study was conducted with the goal of investigating whether the same cognate facilitation effect reported for bilingual adults is also true for bilingual children. To do so, two experiments were carried out. In Experiment 1, 53 Portuguese-speaking (L1) children learning English as a second language (L2) from 3rdand 7thgrade completed lexical decision tasks, which included cognates, noncognates and pseudowords, in both Portuguese and English. In Experiment 2, 18 age-matched English monolinguals performed the English version of the lexical decision task. The results of Experiment 1 showed that the cognate effect was evident for both 3rdand 7thgraders, when the task was performed in the L2. However, no statistical difference between the two grades was found. When performing the task in the L1, the bilingual groups showed no cognate effect, which suggests that these participants had not reached a level of proficiency in which the L2 can influence L1 processing. The results of Experiment 2 showed no cognate facilitation effect for monolinguals, indicating that the results of the early L2 learners, in the English version of the lexical decision task, were indeed due to the cognate status of the words of the bilingual'stwo languages. In short, the present results favor the nonselective view of lexical access and the effect of proficiency in the perception of cross language similarity.A questão da seletividade da língua no acesso lexical de adultos bilíngues tem sido amplamenterelatada na literatura. No entanto, estudos com crianças bilíngues ainda são limitados, principalmente no contexto brasileiro, no qual o número de escolas bilíngues tem aumentado rapidamente nos últimos anos. Para preencher essa lacuna, o presente estudo teve com o objetivo investigar se o mesmo efeito de facilitação cognata relatado no caso de adultos bilíngues também é verdadeiro para crianças bilíngues. Para isso, dois experimentos foram conduzidos. No Experimento 1, um total de 53 crianças falantes nativas de português (L1) aprendendo o inglês como segunda língua (L2), de 3ª e 7ª série, realizaram uma tarefa de decisão lexical que continha cognatos, não-cognatos e pseudopalavras, tanto em português como em inglês. No Experimento 2, 18 monolíngues falantes de inglês realizaram a tarefa de decisão lexical na versão em inglês. Os resultados do Experimento 1 mostraram que o efeito cognato foi evidente para os dois grupos de bilíngues quando a tarefa foi realizada na L2-inglês, embora não tenha sido encontrada diferença estatística entre as séries. Ao realizar a tarefa na L1, os grupos bilíngues não apresentaram efeito cognato, o que indica que esses participantes não atingiram um nível de proficiência em que a L2 pode influenciar o processamento da L1. Os resultados do Experimento 2 mostraram que não houve efeito de facilitação cognata para os monolíngues, indicando que os resultados dos aprendizes precoces de L2, na versão em inglês da tarefa de decisão lexical foram, realmente, devido ao status de cognato das palavras das duas línguas dos bilíngues. Em suma, os presentes resultados favorecem a visão não seletiva do acesso lexical e o efeito da proficiência na percepção da similaridade entre línguas

Prüfung von Perkolations- und Elutionsversuchen zur Schadstofffreisetzung aus mineralischen Ersatzbaustoffen

In einem groß angelegten Ringversuch wurden die DIN-Normen DIN 19528 und DIN 19529 verifiziert. In dieser Arbeit haben wir die darin vorgesehenen Experimente durchgeführt, das Versuchsprogramm erweitert und die Ergebnisse mittels verschiedener mathematischer Verfahren ausgewertet. Schüttelversuche, wie in DIN 19529 vorgesehen, haben wir durch Ansätze mit weiteren Wasser-/Feststoffverhältnissen erweitert. Diese Ergebnisse wurden zur Ermittlung der das Verteilungsverhalten bestimmenden Parameter mittels MuBaX (Iden und Durner, 2007) ausgewertet. Die Säulenversuche nach DIN 19528 wurden ebenfalls in ihrer zeitlichen Dauer erweitert und durch Fließunterbrechungen ergänzt. Für die Abschätzung der kurz- bis mittelfristigen Freisetzungen wurden reproduzierbare und zwischen den unterschiedlichen Methoden vergleichbare Ergebnisse erzielt