Giunzione mediante laser di materiali difficili, ibridi ed a struttura cellulare

Lo studio presentato in questa sede concerne applicazioni di saldatura LASER caratterizzate da aspetti di non-convenzionalità ed è costituito da tre filoni principali. Nel primo ambito di intervento è stata valutata la possibilità di effettuare saldature per fusione, con LASER ad emissione continua, su pannelli Aluminum Foam Sandwich e su tubi riempiti in schiuma di alluminio. Lo studio ha messo in evidenza numerose linee operative riguardanti le problematiche relative alla saldatura delle pelli esterne dei componenti ed ha dimostrato la fattibilità relativa ad un approccio di giunzione LASER integrato (saldatura seguita da un post trattamento termico) per la realizzazione della giunzione completa di particolari tubolari riempiti in schiuma con ripristino della struttura cellulare all’interfaccia di giunzione. Il secondo ambito di intervento è caratterizzato dall’applicazione di una sorgente LASER di bassissima potenza, operante in regime ad impulsi corti, nella saldatura di acciaio ad elevato contenuto di carbonio. Lo studio ha messo in evidenza come questo tipo di sorgente, solitamente applicata per lavorazioni di ablazione e marcatura, possa essere applicata anche alla saldatura di spessori sub-millimetrici. In questa fase è stato messo in evidenza il ruolo dei parametri di lavoro sulla conformazione del giunto ed è stata definita l’area di fattibilità del processo. Lo studio è stato completato investigando la possibilità di applicare un trattamento LASER dopo saldatura per addolcire le eventuali zone indurite. In merito all’ultimo ambito di intervento l’attività di studio si è focalizzata sull’utilizzo di sorgenti ad elevata densità di potenza (60 MW/cm^2) nella saldatura a profonda penetrazione di acciai da costruzione. L’attività sperimentale e di analisi dei risultati è stata condotta mediante tecniche di Design of Experiment per la valutazione del ruolo preciso di tutti i parametri di processo e numerose considerazioni relative alla formazione di cricche a caldo sono state suggerite.

Fallo mecánico debido a grietas en Niobato de Litio bajo irradiación, simulación mediante elementos finitos

Ion-induced nano-track in LiNbO3. Motivation. From macro to nanoscale. Finite element method for nano-structured materials. Simulations of X-cut and Z-cut in LiNbO3. Experiments versus Simulations. Conclusions

Multimode Atomic Pattern Formation via Enhanced Light-atom Interactions

The nonlinear interaction between light and atoms is an extensive field of study with a broad range of applications in quantum information science and condensed matter physics. Nonlinear optical phenomena occurring in cold atoms are particularly interesting because such slowly moving atoms can spatially organize into density gratings, which allows for studies involving optical interactions with structured materials. In this thesis, I describe a novel nonlinear optical effect that arises when cold atoms spatially bunch in an optical lattice. I show that employing this spatial atomic bunching provides access to a unique physical regime with reduced thresholds for nonlinear optical processes and enhanced material properties. Using this method, I observe the nonlinear optical phenomenon of transverse optical pattern formation at record-low powers. These transverse optical patterns are generated by a wave- mixing process that is mediated by the cold atomic vapor. The optical patterns are highly multimode and induce rich non-equilibrium atomic dynamics. In particular, I find that there exists a synergistic interplay between the generated optical pat- terns and the atoms, wherein the scattered fields help the atoms to self-organize into new, multimode structures that are not externally imposed on the atomic sample. These self-organized structures in turn enhance the power in the optical patterns. I provide the first detailed investigation of the motional dynamics of atoms that have self-organized in a multimode geometry. I also show that the transverse optical patterns induce Sisyphus cooling in all three spatial dimensions, which is the first observation of spontaneous three-dimensional cooling. My experiment represents a unique means by which to study nonlinear optics and non-equilibrium dynamics at ultra-low required powers.

Coupled diusion and mechanics in battery electrodes

Thesis (Ph.D.)--University of Washington, 2016-08

Five channel WDM communication using a single a:SiC-H double pin photo device

Amorphous SiC heterostructures built as a double pin device has a non linear spectral gain which is a function of the signal wavelength that impinges on its front or back surface. Illuminating the device with several single wavelength data channels in the visible spectrum allows for Wavelength Division Multiplexing (WDM) digital communication. Using fixed ultra-violet illumination at the front or back surfaces enables the recovery of the multiplexed channels. Five channels, each using a single wavelength which is modulated by a Manchester coded signal at 12,000 bps, form a frame with 1024 bits with a preamble for signal intensity and synchronisation purposes. Results show that the clustering of the received signal enables the successful recovery of the five channel data using the front and back illumination of the surfaces of the double pin photo device. (C) 2015 Elsevier B.V. All rights reserved.

Síntese, caracterização e aplicação de LaSBA-15 e como catalisador para obtenção de biodiesel de soja via rota etílica

Biodiesel is an alternative fuel, renewable, biodegradable and nontoxic. The transesterification of vegetable oils or animal fat with alcohol is most common form of production of this fuel. The procedure for production of biodiesel occurs most commonly through the transesterification reaction in which catalysts are used to accelerate and increase their income and may be basic, acid or enzyme. The use of homogeneous catalysis requires specific conditions and purification steps of the reaction products (alkyl ester and glycerol) and removal of the catalyst at the end of the reaction. As an alternative to improve the yield of the transesterification reaction, minimize the cost of production is that many studies are being conducted with the application of heterogeneous catalysis. The use of nano-structured materials as catalysts in the production of biodiesel is a biofuel alternative for a similar to mineral diesel. Although slower, can esterify transesterified triglycerides and free fatty acids and suffer little influence of water, which may be present in the raw material. This study aimed at the synthesis, characterization and application of nano-structured materials as catalysts in the transesterification reaction of soybean oil to produce biodiesel by ethylic route. The type material containing SBA-15 mesoporous lanthanum embedded within rightly Si / La = 50 was used catalyst. Solid samples were characterized by X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, nitrogen adsorption and desorption. For the transesterification process, we used a molar ratio of 20:1 alcohol and oil with 0.250 g of catalyst at 60°C and times of 6 hours of reaction. It was determined the content of ethyl esters by H-NMR analysis and gas chromatography. It was found that the variable of conversion obtained was 80%, showing a good catalytic activity LaSBA-15 in the transesterification of vegetable oils via ethylic route

Cloud point extraction to avoid interferences by structured background on nickel determination in plant materials by FAAS

An analytical procedure based on microwave-assisted digestion with diluted acid and a double cloud point extraction is proposed for nickel determination in plant materials by flame atomic absorption spectrometry. Extraction in micellar medium was successfully applied for sample clean up, aiming to remove organic species containing phosphorous that caused spectral interferences by structured background attributed to the formation of PO species in the flame. Cloud point extraction of nickel complexes formed with 1,2-thiazolylazo-2-naphthol was explored for pre-concentration, with enrichment factor estimated as 30, detection limit of 5 mu g L(-1) (99.7% confidence level) and linear response up to 80 mu g L(-1). The accuracy of the procedure was evaluated by nickel determinations in reference materials and the results agreed with the certified values at the 95% confidence level.

Self assembled monolayers for engineering of structured inorganic materials in the micrometer and submicrometer range

Deutsch:In der vorliegenden Arbeit konnten neue Methoden zur Synthese anorganischer Materialien mit neuartiger Architektur im Mikrometer und Nanometer Maßstab beschrieben werden. Die zentrale Rolle der Formgebung basiert dabei auf der templatinduzierten Abscheidung der anorganischen Materialien auf selbstorganisierten Monoschichten. Als Substrate eignen sich goldbedampfte Glasträger und Goldkolloide, die eine Mittelstellung in der Welt der Atome bzw. Moleküle und der makroskopischen Welt der ausgedehnten Festkörper einnehmen. Auf diesen Substraten lassen sich Thiole zu einer monomolekularen Schicht adsorbieren und damit die Oberflächeneigenschaften des Substrates ändern. Ein besonderer Schwerpunkt bei dieser Arbeit stellt die Synthese speziell auf die Bedürfnisse der jeweiligen Anwendung ausgerichteten Thiole dar.Im ersten Teil der Arbeit wurden goldbedampfte Glasoberflächen als Template verwendet. Die Abscheidung von Calciumcarbonat wurde in Abhängigkeit der Schichtdicke der adsorbierten Monolage untersucht. Aragonit, eine der drei Hauptphasen des Calciumcarbonat Systems, wurde auf polyaromatischen Amid - Oberflächen mit Schichtdicken von 5 - 400 nm Dicke unter milden Bedingung abgeschieden. Die einstellbaren Parameter waren dabei die Kettenlänge des Polymers, der w-Substituent, die Bindung an die Goldoberfläche über Verwendung verschiedener Aminothiole und die Kristallisationstemperatur. Die Schichtdickeneinstellung der Polymerfilme erfolgte hierbei über einen automatisierten Synthesezyklus.Titanoxid Filme konnten auf Oberflächen strukturiert werden. Dabei kam ein speziell synthetisiertes Thiol zum Einsatz, das die Funktionalität einer Styroleinheit an der Oberflächen Grenze als auch eine Möglichkeit zur späteren Entfernung von der Oberfläche in sich vereinte. Die PDMS Stempeltechnik erzeugte dabei Mikrostrukturen auf der Goldoberfläche im Bereich von 5 bis 10 µm, die ihrerseits über die Polymerisation und Abscheidung des Polymers in den Titanoxid Film überführt werden konnten. Drei dimensionale Strukturen wurden über Goldkolloid Template erhalten. Tetraethylenglykol konnte mit einer Thiolgruppe im Austausch zu einer Hydroxylgruppe monofunktionalisiert werden. Das erhaltene Molekül wurde auf kolloidalem Gold selbstorganisiert; es entstand dabei ein wasserlösliches Goldkolloid. Die Darstellung erfolgte dabei in einer Einphasenreaktion. Die so erhaltenen Goldkolloide wurden als Krstallisationstemplate für die drei dimensionale Abscheidung von Calciumcarbonat verwendet. Es zeigte sich, dass Glykol die Kristallisation bzw. den Habitus des krsitalls bei niedrigem pH Wert modifiziert. Bei erhöhtem pH Wert (pH = 12) jedoch agieren die Glykol belegten Goldkolloide als Template und führen zu sphärisch Aggregaten. Werden Goldkolloide langkettigen Dithiolen ausgesetzt, so führt dies zu einer Aggregation und Ausfällung der Kolloide aufgrund der Vernetzung mehrer Goldkolloide mit den Thiolgruppen der Alkyldithiole. Zur Vermeidung konnte in dieser Arbeit ein halbseitig geschütztes Dithiol synthetisiert werden, mit dessen Hilfe die Aggregation unterbunden werden konnte. Das nachfolgende Entschützten der Thiolfunktion führte zu Goldkolloiden, deren Oberfläche Thiol funktionalisiert werden konnte. Die thiolaktiven Goldkolloide fungierten als template für die Abscheidung von Bleisulfid aus organisch/wässriger Lösung. Die Funktionsweise der Schutzgruppe und die Entschützung konnte mittels Plasmonenresonanz Spektroskopie verdeutlicht werden. Titanoxid / Gold / Polystyrol Komposite in Röhrenform konnten synthetisiert werden. Dazu wurde ein menschliches Haar als biologisches Templat für die Formgebung gewählt.. Durch Bedampfung des Haares mit Gold, Assemblierung eines Stryrolmonomers, welches zusätzlich eine Thiolfunktionalität trug, Polymerisation auf der Oberfläche, Abscheidung des Titanoxid Films und anschließendem Auflösen des biologischen Templates konnte eine Röhrenstruktur im Mikrometer Bereich dargestellt werden. Goldkolloide fungierten in dieser Arbeit nicht nur als Kristallisationstemplate und Formgeber, auch sie selbst wurden dahingehend modifiziert, dass sie drahtförmige Agglormerate im Nanometerbereich ausbilden. Dazu wurden Template aus Siliziumdioxid benutzt. Zum einen konnten Nanoröhren aus amorphen SiO2 in einer Sol Gel Methode dargestellt werden, zum anderen bediente sich diese Arbeit biologischer Siliziumoxid Hohlnadeln aus marinen Schwämmen isoliert. Goldkolloide wurden in die Hohlstrukturen eingebettet und die Struktur durch Ausbildung von Kolloid - Thiol Netzwerken mittels Dithiol Zugabe gefestigt. Die Gold-Nanodrähte im Bereich von 100 bis 500 nm wurden durch Auflösen des SiO2 - Templates freigelegt.

Nanomechanical and phononic properties of structured soft materials

Significant interest in nanotechnology, is stimulated by the fact that materials exhibit qualitative changes of properties when their dimensions approach ”finite-sizes”. Quantization of electronic, optical and acoustic energies at the nanoscale provides novel functions, with interests spanning from electronics and photonics to biology. The present dissertation involves the application of Brillouin light scattering (BLS) to quantify and utilize material displacementsrnfor probing phononics and elastic properties of structured systems with dimensions comparable to the wavelength of visible light. The interplay of wave propagation with materials exhibiting spatial inhomogeneities at sub-micron length scales provides information not only about elastic properties but also about structural organization at those length scales. In addition the vector nature of q allows, for addressing the directional dependence of thermomechanical properties. To meet this goal, one-dimensional confined nanostructures and a biological system possessing high hierarchical organization were investigated. These applications extend the capabilities of BLS from a characterization tool for thin films to a method for unravelingrnintriguing phononic properties in more complex systems.

Towards a sustainable approach for Cultural Heritage Conservation: developing micro-structured green materials and analytical protocols for their performance assessment

Cleaning is one of the most important and delicate procedures that are part of the restoration process. When developing new systems, it is fundamental to consider its selectivity towards the layer to-be-removed, non-invasiveness towards the one to-be-preserved, its sustainability and non-toxicity. Besides assessing its efficacy, it is important to understand its mechanism by analytical protocols that strike a balance between cost, practicality, and reliable interpretation of results. In this thesis, the development of cleaning systems based on the coupling of electrospun fabrics (ES) and greener organic solvents is proposed. Electrospinning is a versatile technique that allows the production of micro/nanostructured non-woven mats, which have already been used as absorbents in various scientific fields, but to date, not in the restoration field. The systems produced proved to be effective for the removal of dammar varnish from paintings, where the ES not only act as solvent-binding agents but also as adsorbents towards the partially solubilised varnish due to capillary rise, thus enabling a one-step procedure. They have also been successfully applied for the removal of spray varnish from marble substrates and wall paintings. Due to the materials' complexity, the procedure had to be adapted case-by-case and mechanical action was still necessary. According to the spinning solution, three types of ES mats have been produced: polyamide 6,6, pullulan and pullulan with melanin nanoparticles. The latter, under irradiation, allows for a localised temperature increase accelerating and facilitating the removal of less soluble layers (e.g. reticulated alkyd-based paints). All the systems produced, and the mock-ups used were extensively characterised using multi-analytical protocols. Finally, a monitoring protocol and image treatment based on photoluminescence macro-imaging is proposed. This set-up allowed the study of the removal mechanism of dammar varnish and semi-quantify its residues. These initial results form the basis for optimising the acquisition set-up and data processing.

Quasimode theory of quantum optical processes in photonic band gap materials

This paper deals with atomic systems coupled to a structured reservoir of quantum EM field modes, with particular relevance to atoms interacting with the field in photonic band gap materials. The case of high Q cavities has been treated elsewhere using Fano diagonalization based on a quasimode approach, showing that the cavity quasimodes are responsible for pseudomodes introduced to treat non-Markovian behaviour. The paper considers a simple model of a photonic band gap case, where the spatially dependent permittivity consists of a constant term plus a small spatially periodic term that leads to a narrow band gap in the spectrum of mode frequencies. Most treatments of photonic band gap materials are based on the true modes, obtained numerically by solving the Helmholtz equation for the actual spatially periodic permittivity. Here the field modes are first treated in terms of a simpler quasimode approach, in which the quasimodes are plane waves associated with the constant permittivity term. Couplings between the quasimodes occur owing to the small periodic term in the permittivity, with selection rules for the coupled modes being related to the reciprocal lattice vectors. This produces a field Hamiltonian in quasimode form. A matrix diagonalization method may be applied to relate true mode annihilation operators to those for quasimodes. The atomic transitions are coupled to all the quasimodes, and the true mode atom-EM field coupling constants (one-photon Rabi frequencies) are related to those for the quasimodes and also expressions are obtained for the true mode density. The results for the one-photon Rabi frequencies differ from those assumed in other work. Expressions for atomic decay rates are obtained using the Fermi Golden rule, although these are valid only well away from the band gaps.

Occupational therapists' use and perceptions of written client education materials

OBJECTIVE. The purpose of this study was to examine occupational therapists' use and perceptions of written education materials for clients and the factors that therapists consider before distributing written materials to clients This study also aimed to determine whether use and perceptions of these materials differed for older clients METHOD. A random sample of 50 occupational therapists from Queensland, Australia, working in adult physical disabilities settings was surveyed with a structured questionnaire Data were analyzed descriptively and with nonparametric statistics RESULTS. Of 49 participants who used written materials, 54% had given them to more than halt of their last 10 clients, regardless of the clients' age Written materials, most often information sheets developed by the participants themselves; handwritten notes; and pamphlets were principally used to reinforce verbal information. Clients' cognitive abilities, primary language, communication skills, vision, and level of education most often were considered before distributing written materials Although participants generally were positive about the content and effectiveness of materials, ratings were significantly less positive related to older clients CONCLUSION. Client education was a core treatment modality for participants in this study, with written media most commonly being used to supplement verbal education Because participants were least positive about the effectiveness of written materials for older clients, further development of materials for this audience may be indicated.

Micro/nano-structured superhydrophobic surfaces in the biomedical field: part I: basic concepts and biomimetic approaches.

Inspired by natural structures, great attention has been devoted to the study and development of surfaces with extreme wettable properties. The meticulous study of natural systems revealed that the micro/nano-topography of the surface is critical to obtaining unique wettability features, including superhydrophobicity. However, the surface chemistry also has an important role in such surface characteristics. As the interaction of biomaterials with the biological milieu occurs at the surface of the materials, it is expected that synthetic substrates with extreme and controllable wettability ranging from superhydrophilic to superhydrophobic regimes could bring about the possibility of new investigations of cellâ material interactions on nonconventional surfaces and the development of alternative devices with biomedical utility. This first part of the review will describe in detail how proteins and cells interact with micro/nano-structured surfaces exhibiting extreme wettabilities.

The nurse in the management of materials in teaching hospitals

OBJECTIVETo present the nurse's integration within materials management of six teaching hospitals of Paraná - Brazil, and to describe the activities performed by nurses within this process.METHODA study of a qualitative approach and descriptive nature, conducted in teaching hospitals in Paraná, between June and August of 2013. The data collection was conducted through semi-structured interviews with eight nurses who worked in materials management; data were analyzed using content analysis.RESULTSThese showed that nurses perform ten categories of activities, distributed into four of the five steps of the materials management process.CONCLUSIONThe nurse, in performing of these activities, in addition to favoring the development of participative management, contributes to the organization, planning, and the standardization of the hospital supply process, giving greater credibility to the work with professionals who use the materials, and to the suppliers.

Wear of two denture teeth materials in vivo-2-year results.

OBJECTIVE: (1) To quantify wear of two different denture tooth materials in vivo with two study designs, (2) to relate tooth variables to vertical loss. METHODS: Two different denture tooth materials had been used (experimental material=test; DCL=control). In study 1 (split-mouth, 6 test centers) 60 subjects received complete dentures, in study 2 (two-arm, 1 test center) 29 subjects. In study 1 the mandibular dentures were supported by implants in 33% of the subjects, in study 2 only in 3% of the subjects. Impressions of the dentures were taken and poured with improved stone at baseline and after 6, 12, 18 and 24 months. Each operator evaluated the wear subjectively. Wear analysis was carried out with a laser scanning device. Maximal vertical loss of the attrition zones was calculated for each tooth cusp and tooth. A mixed linear model was used to statistically analyse the logarithmically transformed wear data. RESULTS: Due to drop-outs and unmatchable casts, only 47 subjects of study 1 and 14 of study 2 completed the 2-year recall. Overall, 75% of all teeth present could be analysed. There was no statistically difference in the overall wear between the test and control material for either study 1 or study 2. The relative increase in wear over time was similar in both study designs. However, a strong subject effect and center effect were observed. The fixed factors included in the model (time, tooth, center, etc.) accounted for 43% of the variability, whereas the random subject effect accounted for another 30% of the variability, leaving about 28% of unexplained variability. More wear was consistently recorded in the maxillary teeth compared to the mandibular teeth and in the first molar teeth compared to the premolar teeth and the second molars. Likewise, the supporting cusps showed more wear than the non-supporting cusps. The amount of wear did not depend on whether or not the lower dentures were supported by implants. The subjective wear was correct in about 67% of the cases if it is postulated that a wear difference of 100μm should be subjectively detectable. SIGNIFICANCE: The clinical wear of denture teeth is highly variable with a strong patient effect. More wear can be expected in maxillary denture teeth compared to mandibular teeth, first molars compared to premolars and supported cusps compared to non-supported cusps. Laboratory data on the wear of denture tooth materials may not be confirmed in well-structured clinical trials probably due to the large inter-individual variability.