Efeito da moagem de alta energia na densificação e microestrutura do compósito AI2O3-Cu

The Cu-Al2O3 composite ceramic combines the phase of alumina, which is extremely hard and durable, yet very brittle, to metallic copper phase high ductility and high fracture toughness. These characteristics make this material a strong candidate for use as a cutting tool. Al2O3-Cu composite powders nanocrystalline and high homogeneity can be produced by high energy milling, as well as dense and better mechanical structures can be obtained by liquid phase sintering. This work investigates the effect of high-energy milling the dispersion phase Al2O3, Cu, and the influence of the content of Cu in the formation of Cu-Al2O3 composite particles. A planetary mill Pulverisatte 7 high energy was used to perform the experiments grinding. Al2O3 powder and Cu in the proportion of 5, 10 and 15% by weight of Cu were placed in a container for grinding with balls of hard metal and ethyl alcohol. A mass ratio of balls to powder of 1:5 was used. All powders were milled to 100 hours, and powder samples were collected after 2, 10, 20, 50 and 70 hours of grinding. Composite powders with compact cylindrical shape of 8 mm diameter were pressed and sintered in uniaxial matrix resistive furnace to 1200, 1300 to 1350 °C for 60 minutes under an atmosphere of argon and hydrogen. The heating rate used was 10°C/min. The powders and structures of the sintered bodies were characterized by XRD, SEM and EDS. Analysis TG, DSC and particle size were also used to characterize the milled powders, as well as dilatometry was used to observe the contraction of the sintered bodies. The density of the green and sintered bodies was measured using the geometric method (mass / volume). Vickers microhardness with a load of 500 g for 10 s were performed on sintered structures. The Cu-Al2O3 composite with 5% copper density reached 61% of theoretical density and a hardness of 129 HV when sintered at 1300 ° C for 1h. In contrast, lower densities (59 and 51% of the theoretical density) and hardness (110 HV and 105) were achieved when the copper content increases to 10 and 15%.

STUDIES OF FUNCTIONALIZED NANOPARTICLES FOR SMART SELF-ASSEMBLY AND AS CONTROLLED DRUG DELIVERY

This dissertation is related to the studies of functionalized nanoparticles for self-assembly and as controlled drug delivery system. The whole topic is composed of two parts. In the first part, the research was conducted to design and synthesize a new type of ionic peptide-functionalized copolymer conjugates for self-assembly into nanoparticle fibers and 3D scaffolds with the ability of multi-drug loading and governing the release rate of each drug for tissue engineering. The self-assembly study confirmed that such peptide-functionalized amphiphilic copolymers underwent different self-assembly behavior. The bigger nanoparticles were more easily assembled into nanoparticle fibers and 3D scaffolds with larger pore size, while the smaller nanoparticle underwent faster self-assembly to form more compact 3D scaffolds with smaller porosity but more stable structure. Controlled release studies confirmed the ability of governing simultaneous release of different model drugs with independent release rate from a same scaffold. Cytotoxicity tests showed that all synthesized peptides, copolymers and peptide-copolymer conjugates were biocompatible with SW-620 cell lines and NIH3T3 cell lines. This new type of self-assembled scaffolds combined the advantages of peptide nanofibers and versatile controlled release of polymeric nanoparticles to achieve simultaneous multi-drug loading and controlled release of each drug, uniform distribution and flexibility of hydrogel scaffolds. The investigations in second part were first to design and synthesize organic biocide-loaded nanoparticles for low-leaching wood preservation using a cost-effective one-pot method to synthesize amphiphilic chitosan-g-PMMA nanoparticles loading with ~25-28 wt.% of the fungicide tebuconazole with particle size of ~100 nm diameter by FESEM. FESEM analysis confirmed efficient penetration of nanoparticles throughout the treated wooden stake with dimension of 19 × 19 × 455 mm^3. Leaching studies showed that biocide introduced into sapwood via nanoparticles leached only ~9% compared with the amount leached from tebuconazole solution-treated control, while soil jar tests showed that the nanoparticle-treated wood blocks were effectively protected from biological decay tested against G. trabeum, a brown rot fungus. Copper oxide nanoparticles with and without polymer stabilizers were also investigated to use as inorganic wood preservatives to clarify the factor affecting copper leaching from treated wood. Copper oxide nanoparticles with uniform diameters of ~10 nm and ~50 nm were prepared, and the leachates from southern pine sapwood treated with these nanoparticles were analyzed. It was found by TEM and EDS analysis that significant numbers of nanoparticles leached from the treated wood. The 50 nm nanoparticles leached slightly less than a soluble copper salt control, but 10 nm nanoparticles leached substantially more than the control. The effect of polymer stabilizers on nanoparticle leaching was also investigated. Results showed that polymer stabilizers increased leaching. The trends showed that nanoparticle size was a major factor in copper leaching.

Francisco Pizarro' s banner of arms: an analytical work contributing to latin America's history

The study of textiles is an open area of scientific research, which for its variety of material components and physical chemical diversity of conditions, makes a field of interest for scientific studies in the cultural heritage field. Archaeological/historical textiles offer the possibility to carry out studies on organic materials such as fibers, adhesion elements, dyes, paper, etc., as well as on inorganic compounds for instance metals, alloys, precious stones and other added ornamentation. That variety of composition, allow to use a combination of analytical techniques to solve the questions coming from the object in an archaeometric research. One kind of textile object that provides a valuable cultural information because of its linguistic representation employed by its carrier societies, are the flags/banners/emblems, objects made with a nonverbal communication purpose. As long as depending on the use and/or purpose of each object, varies both the materials/techniques used in its production and its iconography (style, color, emblem, shape), its study gives the possibility to extract information through their materials and manufacturing techniques about a temporal-spatial frame, a particular event or a specific character. The flags/banners have been used since the eleventh century as representative objects of power, hierarchy, social or military organization, or as communicative media. The use of these objects has been spread throughout the world, possibly due to its easy interpretation and/or appropriation by different societies, making it part of their own culture. The flags as symbols of territorial control, using emblems that represent a family, order or army, were introduced to the New World (America) with the arrival of the European conquerors at the end of the fifteenth century. Flags/banners representing the Royal dominion over conquered territories, the Catholic Church and conquistadors’ armies were the first to arrive. One of those flags that have endured over time, that have an invaluable cultural meaning for both American and Iberian societies, is the so-called Francisco Pizarro’s Banner of Arms. It is a textile object with metal threads decoration over a Royal emblem. According to historical sources, this object was used by Francisco Pizarro in 1532 on the conquest process of Peru, after received the permission by King Charles V to on behalf of him, to conquer the lands of the New World today known as Peru. After Pizarro’s control of the Inca territory, it is believed that Pizarro left his banner on top of the Inca’s Sun’s Temple as symbol of his rule. Centuries later, in the America libertarian campaigns, General Sucre, military at charge of the independence army in Peru, reports have found what he considered the Pizarro’s Banner, sending it to Bogotá as a symbol of victory, being kept since that time until today by the National Museum of Colombia. Due to historical discrepancies in the different movements of the so-called Pizarro’s Banner of Arms, its real meaning has been under discussion and because of the passage of time its physical condition has suffer deterioration. That is because its scientific study is now an interesting case study to respond to both historical and conservation questions of it. Through a collaboration with the National Museum of Colombia, a set of 25 samples of so-called Pizarro’s Banner of Arms were collected, covering the various components and areas from the object of study. These samples were subjected to analytical studies for physical and chemical characterization. Microscopic observation, VSEM-EDS analysis, Raman spectroscopy, chromatographic analysis (HPLC-MS, GCMS) and radiocarbon dating were done. Similarly, was sought through a direct in situ physical inspection to the object and through a research into historical sources, adequate information to solve the object’s problems. Results obtained allowed to identify as silk the textile used in the elaboration of the Banner’s fabric, as well as the use of natural dyes for dyeing the fibers used on the emblem: use of cochineal and brazil wood as a source of red, luteolin plant-based for yellow color, indigotine plant-based for blue, and a mixture of yellow and blue dyes for green were identified. Similarly, the use of animal glue in the manufacturing process and the use of rag paper was evident. The metal threads study from the Banner give a confirmation to a silver core wire gilded with a thin gold sheet, being flattened and entwined with silk threads for their use. Finally, using the radiocarbon results, it was possible to postulate with huge accuracy that the Banner date manufacture was between the XV-XVI century and subject to restoration processes with addition of textiles in modern times. Together with, was evident that the state of degradation of the fabric is due to natural degradation in the silk fibers, having that its color has faded and its mechanical properties decreased, leading to loss of rigidity and disappearance of the physical structure. Similarly, it was clear the original colors of the emblem and highlight problems of detachment of paper due to crystallization of the adhesive. In the same way, was found that the metal threads suffer corrosion by sulfur and detachment of its crystals. Finally, combining the analytical results and the historical sources data found from the so-called Francisco Pizarro’s Banner of Arms, allows to postulate that its manufacture process was done in Europe employing precious materials to obtain a long-life object with a deep message for its viewers. Also, the data obtained helps to support the possible idea that the object was employed by Francisco Pizarro in the Peru conquest process. However, by the symbols present in the object, its elaboration date and materials, this object its clearly unique in its kind, and the most important, by its linguistic message, does not represent to Francisco Pizarro or his army, meanwhile, represents the Spanish crown. Therefore, instead to be labeled as Francisco Pizarro’s Banner of Arms, it should be called the Colonial Royal Banner of Charles V in the New World; RESUMEN: El estudio de textiles es un área abierta de investigación científica, la cual por su variedad de componentes materiales y la diversidad de condiciones físico-químicas presentes en estos objetos, lo hace un campo de interés para estudios científicos en el patrimonio cultural. Los textiles arqueológicos/históricos brindan la posibilidad de realizar estudios en materiales orgánicos como fibras, elementos de adhesión, tinturas, papel, etc., e inorgánicos como metales, aleaciones, piedras preciosas y demás materiales decorativos añadidos. Por su variedad de composición, es posible emplear diversas técnicas analíticas para resolver aquellas preguntas propias del objeto en una investigación arqueométrica. Uno de los objetos textiles que brinda gran información cultural debido a su representación lingüística empleada por las sociedades portadoras, son las banderas/estandartes/emblemas. Donde varía dependiendo de su uso y/o propósito, los materiales empleados en su elaboración, al igual que su iconografía (estilo, color, emblema, forma). El estudio de estos objetos construidos con un propósito de comunicación no verbal, da la posibilidad de extraer información a través de sus materiales y técnicas de elaboración sobre un rango temporal-espacial, un evento determinado en la historia o incluso a un personaje en específico. Las banderas han sido empleadas desde el siglo XI como objetos representativos de poder, jerarquía, organización social o militar, o como medio de comunicación. El uso de estos objetos se ha extendido a lo largo del mundo posiblemente debido a su fácil interpretación y/o apropiación por distintas sociedades, haciéndolo parte de su cultura. Las banderas como símbolos de control territorial, empleando símbolos que representan a una familia, orden o armada fueron introducidas a el Nuevo Mundo (América) con la llegada de los conquistadores europeos al final del siglo XV. Las banderas/estandartes que representaban el dominio Real sobre territorios dominados, la iglesia católica y las banderas de ejércitos y/o conquistadores fueron las primeras en llegar al nuevo mundo. Una de aquellas banderas que ha soportado el paso del tiempo, teniendo un gran valor cultural tanto para las sociedades americanas como para las ibéricas, es el denominado Estandarte de armas de Francisco Pizarro. Siendo un objeto textil con decoración en hilos metálicos sobre un emblema Real. De acuerdo a fuentes históricas, este objeto fue usado por Francisco Pizarro en 1532 en el proceso de conquista del Perú, quien recibe por parte del Rey Carlos V el poder para que, en su nombre, Pizarro pueda conquistar las tierras del nuevo mundo hoy conocidas como Perú. Luego del dominio de Pizarro sobre el territorio Inca, se cree que Pizarro dejó su estandarte en la cima del templo Inca del sol como símbolo de su control. Siglos más tarde, en las campañas libertarias de América, el General Sucre, militar encargado de la armada independentista en Perú, reporta haber encontrado lo que él considera como el estandarte de Pizarro, enviándolo a Bogotá como muestra de victoria, siendo custodiada desde ese momento por el Museo Nacional de Colombia hasta la actualidad. Debido a discrepancias históricas, el verdadero significado del llamado estandarte de Pizarro ha sido objeto de discusión y debido del pasar del tiempo su estado de conservación se ha deteriorado. Dejando de este modo, un caso de estudio interesante para que por medio de estudios científicos al objeto se pueda dar respuesta a preguntas tanto históricas como de conservación del mismo. De este modo, por medio de una colaboración con el Museo Nacional de Colombia, se obtuvo un juego de 25 muestras del llamado Estandarte de armas de Francisco Pizarro, abarcando los diferentes componentes y áreas del objeto de estudio. Dichas muestras fueron sometidas a estudios analíticos para su caracterización físico-química. Análisis de observación al microscopio, análisis VSEM-EDS, espectroscopia Raman, análisis cromatográficos (HPLC-MS, GC-MS) y datación por radiocarbono catorce fueron realizados. Del mismo modo, por medio de una inspección física al objeto in situ y una profunda investigación en fuentes históricas del mismo, se buscó la información adecuada para resolver sus problemáticas. Los resultados obtenidos permitieron identificar como seda el textil empleado en la elaboración del estandarte, así como el uso de colorantes naturales para teñir las fibras en el emblema: uso de cochinilla y palo de Brasil como fuente del color rojo, plantas a base de luteolin para el color amarillo, plantas a base de indigotina para el color azul y mezcla de colorantes amarillos y azules para el color verde fueron identificadas. Del mismo modo se evidencio el uso de adhesivos animales y el uso de papel de trapos en el proceso de manufactura. El estudio de los hilos metálicos, permitió evidenciar el uso de alambres con núcleos de plata con un fino recubrimiento de oro en su exterior, siendo aplanados y entrelazados con hilos de seda para su uso. Finalmente usando la datación por radiocarbono, fue posible conocer con alta precisión que el estandarte fue elaborado entre los siglos XV-XVI y sufrió procesos de restauración con añadidura de textiles en tiempos modernos. Junto a lo anterior, es posible postular que el estado de degradación de la tela es debido a degradación natural en las fibras de seda, teniendo así que su color se ha desvanecido y sus propiedades mecánicas disminuidas, conllevando a perdida de rigidez y desaparición de la estructura. Del mismo modo se pudo conocer los colores originales del emblema y evidenciar problemas de desprendimiento del papel debido a cristalización del adhesivo. Asimismo, se comprobó que los hilos metálicos presentan corrosión por azufre y desprendimiento de sus cristales. Finalmente, combinando los resultados analíticos y la información de fuentes históricas encontradas del llamado Estandarte de armas de Francisco Pizarro, se puede postular que su elaboración fue realizada en Europa, usando materiales preciosos para obtener un objeto de larga vida con un profundo mensaje para sus observadores. También, los datos obtenidos ayudan a dar soporte la posible idea de que este objeto fue usado por Francisco Pizarro en el proceso de conquista del Perú. Sin embargo, debido a los símbolos presentes en el objeto, fecha y materiales de elaboración, este objeto es claramente único en su tipo, y lo más importante, por su mensaje lingüístico, este no representa a Francisco Pizarro o su armada, al contrario, representa a la Corona de España. Por ende, en vez de denominarse como Estandarte de armas de Francisco Pizarro, este objeto debería nombrarse como el Estandarte Real de la Colonia de Carlos V en el Nuevo Mundo.

Development of mev-eds methodology for forensic analysis on automotive headlights

A comparative study between three automotive headlights (conventional, halogen, and HID lamp) using scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS) is described. Results show the possibility of conducting topographic and qualitative analysis of automotive light bulbs from vehicles involved in traffic accidents on the basis of similarities between the waste glass material left on the filaments. This should provide evidence as to whether the bulbs were energized at the time of the accident.

Ball Recovery in the Handball Tournament of the 2008 Beijing Olympic Games: Sequential Analysis of Positional Play as Used by the Spanish Team’s Defence

In sport there is a great need to obtain as much information as possible about the factors which affect the dynamics of play. This study uses sequential analysis and temporal patterns (T-patterns)to examine the evolution of defence (against an equal number of attackers)as used by the Spanish handball team at the Beijing 2008 Olympic Games. The aim is to help handball coaches (during their training and gathering of professional experience)to understand the importance of the structure of defensive systems. This can be achieved through observational processes that reveal the evolution and adaptation of these defensive systems according to different variables: the match score, the response of the opposing team and progress through the tournament.

Superefficiency and Multiplier Adjustment in Data Envelopment Analysis

Copyright © 2013 Springer Netherlands.

Hierarchical cluster analysis of groups of individuals : application to business data

3rd SMTDA Conference Proceedings, 11-14 June 2014, Lisbon Portugal.

On cluster analysis of complex and heterogeneous data

3rd SMTDA Conference Proceedings, 11-14 June 2014, Lisbon Portugal.

Cutting forces and wear analysis of Si3N4 diamond coated tools in high speed machining

Si3N4 tools were coated with a thin diamond film using a Hot-Filament Chemical Vapour Deposition (HFCVD) reactor, in order to machining a grey cast iron. Wear behaviour of these tools in high speed machining was the main subject of this work. Turning tests were performed with a combination of cutting speeds of 500, 700 and 900 m min−1, and feed rates of 0.1, 0.25 and 0.4 mm rot−1, remaining constant the depth of cut of 1 mm. In order to evaluate the tool behaviour during the turning tests, cutting forces were analyzed being verified a significant increase with feed rate. Diamond film removal occurred for the most severe set of cutting parameters. It was also observed the adhesion of iron and manganese from the workpiece to the tool. Tests were performed on a CNC lathe provided with a 3-axis dynamometer. Results were collected and registered by homemade software. Tool wear analysis was achieved by a Scanning Electron Microscope (SEM) provided with an X-ray Energy Dispersive Spectroscopy (EDS) system. Surface analysis was performed by a profilometer.

Earth-based repair mortars: experimental analysis with different binders and natural fibers

RESTAPIA 2012 - Int. Conf. on Rammed Earth Conservation, Valencia, 21-23 June 2012

Analysis, testing and development of safe cleaning methods of rusted stone material

Three different treatments were applied on several specimens of dolomitic and calcitic marble, properly stained with rust to mimic real situations (the stone specimens were exposed to the natural environment for about six months in contact with rusted iron). Thirty six marble specimens, eighteen calcitic and eighteen dolomitic, were characterized before and after treatment and monitored throughout the cleaning tests. The specimens were characterized by SEM-EDS (Scanning Electron Microscopy coupled with Energy Dispersion System), XRD (XRay Diffraction), XRF (X-Ray Fluorescence), FTIR (Fourier Transform Infrared Spectroscopy) and color measurements. It was also made a microscopic and macroscopic analysis of the stone surface along with the tests of short and long term capillary absorption. A series of test trials were conducted in order to understand which concentrations and contact times best suits to this purpose, to confirm what had been written to date in the literature. We sought to develop new methods of treatment application, skipping the usual methods of applying chemical treatments on stone substrates, with the use of cellulose poultice, resorting to the agar, a gel already used in many other areas, being something new in this area, which possesses great applicability in the field of conservation of stone materials. After the application of the best methodology for cleaning, specimens were characterized again in order to understand which treatment was more effective and less harmful, both for the operator and the stone material. Very briefly conclusions were that for a very intense and deep penetration into the stone, a solution of 3.5% of SDT buffered with ammonium carbonate to pH around 7 applied with agar support would be indicated. For rust stains in its initial state, the use of Ammonium citrate at a concentration of 5% buffered with ammonium to pH 7 could be applied more than once until satisfactory results appear.

Analysis of applications and of conceptions for an application-oriented mathematics instruction

In connection with the (revived) demand for considering applications in the teaching of mathematics, various schemata or lists of criteria have been developed since the end of the sixties, which set up requirements about closeness to the real world or about the type of mathematics being used, and which have made it possible to analyze the available applications in their light. After having stated the problem (in section 1), we present (in section 2) a sketch of some of the best known of these and of some earlier schemata, although we are not aiming for a complete picture. Then (in section 3) we distinguish among different dimensions.in the analysis of applications. With this as a basis, we develop (in section 4) our own suggestion for categorizing types of applications and conceptions for an application-oriented mathematics instruction. Then (in section 5) we illustrate our schemata by some examples of performed evaluations. Finally (in section 6), we present some preliminary first results of the analysis of teaching conceptions.