bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of low temperature coating and annealing on structural and optical properties of CdSe/CdS core/shell QDs
Authors: Isarov Maya , Grumbach N. , Maikov Georgy I. , Tilchin Jenya , Jang Youngjin , Sashchiuk Aldona , Lifshitz Efrat
Published: January 2016

This paper presents the optical temperature dependent properties, over a wide range of temperatures from 4 to 300 K, of new CdSe/CdS core/shell colloidal quantum dots (QDs) with varying shell thickness coated and annealed at low temperature. It was demonstrated that low temperature coating and annealing processes enhanced the photoluminescence (PL) quantum yield accompanied by variation in the QDs structure, formation of an alloyed interface layer, suppression of the number of defects at the CdSe/CdS interface, band gap energy red-shift, narrowing of CdS longitudinal optical phonon band, and decrease of the PL inhomogeneous broadening parameter.
La olla a presión: cómo la seguridad fronteriza sigue aumentando el caos
Authors: Andersson Ruben
Published: January 2016

Este artículo plantea los problemas y contradicciones del llamado «efecto globo» en los procesos migratorios y la necesidad de partir de una visión global e interconectadas de los flujos poblacionales a través de las fronteras para la elaboración de políticas migratorias justas y efectivas. La revisión de las «crisis» en las fronteras del Mediterráneo, desde las primeras «pateras» que cruzaban Gibraltar hasta la presente «crisis de refugiados», evidencia el hecho de que la presión sobre unas rutas potenciales de entrada no disuade de la voluntad de cruce de frontera sino que desplaza a los emigrantes o refugiados en otras direcciones. Los datos etnográficos muestran cómo por ejemplo el ahora muy elogiado modelo español de gestión de los flujos migratorios en el Mediterráneo no acabó con el problema sino que provocó el desplazamiento de los flujos migratorios hacia caminos más peligrosos en el Sahara y en el norte de África. El problema de España pasó a convertirse en el problema de Italia y, a medida que se desplazaba las rutas, después en el de Grecia, un círculo vicioso que manifiesta el fracaso de las políticas europeas. El autor sigue las historias de personas con las que trabajó etnográficamente, desde Senegal hasta Marruecos, que en sus tránsitos africanos se han visto atrapadas entre vallas, fronteras, dispositivos tecnológicos y mafias de «pasadores». Las experiencias de los inmigrantes señalan un proceso en progresivo aumento: la globalización y mercantilización de las rutas irregulares que emergen paralelamente a los dispositivos migratorios.
Externalización fronteriza en el Mediterráneo Occidental: movilidades, violencias y políticas de compasión
Authors: Jiménez-Álvarez Mercedes G.
Published: January 2016

Basándose en un trabajo de campo de larga duración en Tánger y la frontera entre España y Marruecos, este artículo aborda el efecto de la externalización de la frontera en Marruecos, con un énfasis especial en la experiencia de los niños y jóvenes que atraviesan fronteras en sus proyectos migratorios. A partir del Programa de La Haya de 2004, la deslocalización del control fronterizo empieza a estar presente en la política europea mediante la integración progresiva de terceros países en las tareas de control. Para analizar todos estos procesos, el artículo nos traslada a Bujalef, un barrio «de espera» de la periferia de Tánger —conceptualizado como «penúltima frontera »— donde tuvo lugar un violento desalojo de inmigrantes subsaharianos en julio de 2015. En este contexto, la autora expone las tres lógicas de gobierno del control fronterizo: la violencia cotidiana —expresada en la falta de seguridad jurídica y la represión—, la movilidad aleatoria —una respuesta lógica al control externalizado—, y la compasión —imbricada en la estructura de la acción humanitaria. El trabajo refuerza la idea de que el respeto a los derechos humanos no es una idea que corra paralela a deslocalización fronteriza.
Los centros de internamiento de extranjeros (CIEs) entre control migratorio y control social: una frontera interna y polimorfa
Authors: Barone Sabina
Published: January 2016

Los CIEs son centros de reclusión de personas extranjeras sin documentos de residencia válidos o vigentes y este trabajo los piensa como parte del régimen fronterizo que hemos explorado aquí. Dentro del territorio europeo, con un oscurantista tratamiento de sus procedimientos y del respeto a los derechos humanos de los allí retenidos, los CIEs representan la constante amenaza de retención y expulsión de los extranjeros. Y no sólo sobre la población recién llegada al país, sino también sobre la ya residente, incluyendo a la población extranjera con arraigo. Se trata de «fronteras internas» que crean un sistema de control social polimorfo y provocan una sensación de miedo ante la potencial detención si se incurre en algún supuesto administrativo. Contra las retóricas de integración, los CIEs representan la constante amenaza de expulsión. Si bien los antropólogos no podrían haber accedido al interior de estos espacios de internamiento, la etnografía comprometida del voluntariado nos introduce a las historias de vida de los recluídos. Ello nos permite cuestionar la construcción de la noción de «migrante irregular» y de la agenda política alrededor de la lucha a la migración irregular y el control de los flujos para denunciar la problematicidad de los CIEs que manifiestan una escisión entre el planteamiento universalista de los DDHH y una aplicación injustamente restrictiva de los mismos.
Yoga en España. Proceso de regulación profesional
Authors: Albert Rodrigo María
Published: January 2016

El desarrollo de nuevas espiritualidades va acompañado de emergentes movimientos físicopsico-espirituales que han tenido un claro impacto en ámbitos distintos, pero especialmente en el de la salud y el bienestar debido a su intensa proliferación. Cada día es más frecuente encontrar enfermeros/as que ofrecen yoga a sus pacientes, médicos/as que recomiendan mindfulnes (meditación), etc. El uso de las llamadas Medicinas Alternativas y Complementarias (MAC) ocupa un lugar cada vez más destacado en nuestra sociedad. Se trata de una realidad ya bien visible en los conocidos centros, escuelas, consultas particulares, etc. de terapias alternativas. La proliferación de todos estos espacios terapéuticos camina de la mano de la necesidad de una regulación institucional tanto para el reconocimiento de profesionales que operan en este campo como para su formación. España, hoy es protagonista de un importante avance en materia jurídica en la regulación de la Instrucción en Yoga a raíz de los Reales Decretos publicados en los últimos años, así como de los procesos de acreditación y de habilitación de los profesores de yoga en el caso catalán. En este artículo vamos a ver como se está realizando dicho proceso, mostrando los interrogantes que se han generado, los acuerdos y las discrepancias entre el sector y la administración, así como dentro del propio sector.
Expansión Hare Krishna en contextos de crisis: resignificando la movilización social desde una perspectiva religiosa en Chile
Authors: Bahamondes González Luis Andrés , Marín Alarcón Nelson
Published: January 2016

La presente investigación se focalizará en la expansión del movimiento Hare Krishna en Santiago de Chile, analizando los discursos y mecanismos de movilización que desarrollan sus integrantes frente al escenario de agitación social vivido con la llegada del nuevo milenio. Con ello no solo se buscará vislumbrar las transformaciones internas acaecidas en el movimiento durante el último tiempo, sino además pretendemos identificar estrategias de acción social y políticas independientes frente a inquietudes o problemas sociales instalados en la agenda pública. De esta forma, analizaremos la manera como este grupo religioso se posiciona activamente en un escenario de demandas sociales y guía su accionar desde la particularidad filosófica y espiritual de su doctrina.
Autorías antropológicas y usufructos legitimadores en los procesos memoriales peruanos a propósito de la Comisión de la Verdad y Reconciliación
Authors: Martínez-Magdalena Santiago
Published: January 2016

El conflicto armado peruano (1980-2000) fue asumido institucionalmente mediante la investigación de la Comisión de la Verdad y Reconciliación (CVR) en 2001, acreditando con un Informe final hechos, víctimas y victimarios, y las responsabilidades subsecuentes, así como las recomendaciones y programas de reparación y reconciliación nacional. Intelectuales y profesionales de la Antropología tuvieron un protagonismo muy acentuado en ella, y, antes, en la elaboración analítica de los sucesos in situ mientras iban ocurriendo. Este Informe puede ser considerado un monumento nacional en la reciente historia del Perú, aunque cabe preguntarse si asumió las identidades étnicas victimadas. Por otra parte, la Antropología, dentro y fuera de las instituciones, experimentó usos bastardos en su nombre con el fin de legitimar posiciones distintas, acomodadas a veces en ficciones narrativas encontradas. En este contexto es preciso preguntarse por labor de los intelectuales y la antropología como principios de autoridad y legitimación, y a la Antropología misma como lugar plausible de enunciación política.
La arquitectura de la «nueva periferia»: dinámicas socioculturales urbanas en el PAU de Vallecas
Authors: Vaquerizo Gómez Elena
Published: January 2016

El PAU de Vallecas es uno de los nuevos barrios creados a principios del siglo XXI en el contexto del boom inmobiliario. Se analizan las características de esta «nueva periferia» desde la perspectiva de su arquitectura, entendiendo esta como un dispositivo cultural en el que cristalizan diversas dinámicas urbanas. En el PAU de Vallecas coexiste una doble lógica. Primero, una morfología funcionalista asociada a la hegemonía cultural de la arquitectura moderna y a la acumulación de capital financiero-inmobiliario. Segundo, proyectos arquitectónicos innovadoressostenibles vinculados a la elaboración de una imagen de Madrid y a la competencia interurbana por la atracción de recursos. Además, se hace un pequeño esbozo de algunos procesos que relativizan la idea de una nueva periferia. Se concluirá planteando que estas dos lógicas arquitectónicas diferenciadas constituyen dos elementos de un mismo modelo de gobierno urbano: el empresarialismo urbano.
Selection of Material Base of External Wall in Term of Thermal Performance
Authors: Binek Kamil , Žilinský Juraj
Published: January 2016

Nowadays, the residential buildings are highly demands in every aspect. From technical point of view, it is necessary to observe required thermal performance of buildings structures, which are included in the Slovak technical standard STN 73 0540-2, 31:a) boundary conductance (thermal resistance) b) the internal surface temperature of the building structure c) the amount of condensed and evaporated water vapor in building structures for a year d) heat absorption capacity of floor structure e) annual energy needs for heating f) thermal stability of locality [1]Accomplishment of those requirements should ensure thermal comfort in the living rooms of the building. Thermal comfort is commonly defined as a feeling of satisfaction with the thermal aspects of environment, in which the person does not feel hot or cold. This definition means, that the user does not wish hotter or colder environment. [2]. This feeling of thermal comfort can only be achieved, by optimal design of the entire building, in which they will not neglect the broader relationships as: orientation or building location on the land. Of course it is very important to design cover construction well, as thermal performance view as material base view, where should we make provision for thermal loss, phase change, thermal accumulation etc.
Condensation of Water Vapour in the Functional Gap of Window - Experimental Measurement of Exfiltration at 15 Pa
Authors: Palková Adela , Kamenický Ľuboš , Palko Milan
Published: January 2016

The article is focused on the experimental analysis of water vapour in functional gap of wooden window. The experimental measurements were held in a laboratory of heat engineering of the Slovak university of Technology in Bratislava – in a big climatic chamber for synergic phenomena of heat transfer, water vapour diffusion and air filtration.
Performance-Based Generative Design and Fabrication
Authors: Tholt Tomáš , Löffler Robert , Pernecký Ján , Šimkovič Vladimír
Published: January 2016

The deterministic approach (philosophy) considers natural and civilizational phenomena (architecture) as a result of complex interactions and relations between passive and active actors. This view of architecture has a very close relation to digital methods. It has developed from automatized processes of design through parametric approach to the generative and emergent design. Architecture emerges as a non-linear interaction of endogenous and exogenous forces. It is technically impossible to predict this process (to plan or sketch it). It is, on the other hand possible to simulate it in digital as well as physical world. According to paradigm of emergent design, material and fabrication tool may be considered to be agents of the design process. A long-term goal of the research activities in the collaboration between Academy of Performing Arts, Faculty of Architecture at Slovak University of Technology and an independent platform Rese arch with the KUKA robotic arm is to create an emergent fabrication tool (process).
Laboratory Experimental Verification of the Effectiveness of Acoustical Treatment of Façade Element Frame Profiles
Authors: Bielek Boris , Szabó Daniel
Published: January 2016

Development of modular transparent elemental façade. Laboratory experimental verification of a façade panel and optimization of its acoustic parameters. Measured samples. Laboratory equipment. Methodology of measurement. Results and conclusions of laboratory experiment.
On the Finite Element Method Application for Approximation of Free-Surface Flows with Surface Tension and Contact Angles
Authors: Sváček Petr
Published: January 2016

This paper focuses on the mathematical modelling and the numerical approximation of the flow of two immiscible incompressible fluids,which is influenced by the surface tension and the contact angle effects. The weak formulation is introduced, discretized in time, and the finite element method is applied. The surface tension effects are taken into account using the variational reformulation. The stability of the discrete problem is increased using the implicit formulation of the surface tension. The free surface motion is treated with the aid of the level set method. The numerical results are shown.
Modified Approach to the Simulations of Bus Driving Tests
Authors: Polach Pavel , Václavík Jaroslav
Published: January 2016

The Triple Hybrid Hydrogen Bus project comprises research and development, implementation and a test operation of a city bus with hybrid electric propulsion using hydrogen fuel cells. The mass distribution and the total bus mass are rather different from common buses. This is, among others, the reason for investigating the bus driving stability. In order to obtain a tool for dynamic analysis, multibody models of the bus were created. Verification of multibody models was performed based on the comparison of simulation results and experimental measurements focused on handling behaviour of the bus. To perform the simulations two approaches were used. The first (original) one, at which the initial position of the bus multibody model at the beginning of the simulation of the manoeuvre depends on the bus motion trajectory, and the second (new) one, at which the initial position of the bus multibody model at the beginning of the simulation of the manoeuvre is set an equilibrium position.
Amplitude-Temperature Analysis of Hard Rubber by Torsional Vibration
Authors: Šulc Petr , Pešek Luděk , Bula Vítězslav , Cibulka Jan , Košina Jan
Published: January 2016

This paper deals with an experimental analysis of hard rubber dynamic tests under finite torsion deformations. The experimental test rig was designed and composed for torsion loading of rubber under defined amplitudes, frequencies and temperatures. The present paper brings an amplitude-temperature analysis of isoprene-butadiene rubber ascertained by the use of the test rig. The mathematical rheological model of rubber was designed for phenomenological description and parametric identification of rubber.
Fatigue Testing of Polymeric Hollow Fibre Heat Transfer Surfaces by Pulsating Pressure Loads
Authors: Brožová Tereza , Luks Tomáš , Astrouski Ilya , Raudenský Miroslav
Published: January 2016

This article deals with fatigue tests of polymeric hollow fibre heat transfer surfaces. The hollow fibres have an outer diameter between 0.5-0.8 mm and wall thickness 10 % of the outer diameter. These plastic heat transfer surfaces have some limitations but also many benefits. One of the limitations is the durability of plastic under fatigue loading. The heat transfer surfaces were subjected to pulsating pressure loads under different conditions (level of pressure, ambient temperature, number of cycles). Firstly, only an internal hydraulic pulsating load was applied and the behaviour of the hollow fibres was observed, focusing especially on the presence of leaks, ruptures, etc.Then, other conditions of operations were added. The heat transfer surfaces were immersed in a hot bath and loaded by internal pulsating pressure and high temperature simultaneously. Testing under different temperatures is important because the temperature significantly affects the material properties. The presence of leaks, ruptures and other possible damage was monitored as with previous tests.
Parallel Computing Procedure for Dynamic Relaxation Method on GPU Using NVIDIA's CUDA
Authors: Rek Václav , Němec Ivan
Published: January 2016

This paper introduces a procedure for parallel computing with the Dynamic Relaxation method (DR) on a Graphic Processing Unit (GPU).This method facilitates the consideration of a variety of nonlinearities in an easy and explicit manner.Because of the presence of inertial forces, a static problem leads to a transient dynamic problem where the Central Difference Method is usedas a method for direct integration of equations of motion which arise from the Finite Element model.The natural characteristic of this explicit method is that the scheme can be easily parallelized. The assembly of a global stiffness matrix is not required.Due to slow convergence with this method, the high performance which GPUs provide is strongly suitable for this kind of computation.NVIDIA's CUDA is used for general-purpose computing on graphics processing units (GPGPU) for NVIDIA's GPUs with CUDA capability.
Issue of Rigidity of the Ball Screw Nut Exposed to Bending Stress during Bending Stress of the Ball Screw
Authors: Novotný Lubomír W. , Marek Jiří , Marek Tomáš
Published: January 2016

Ball screws and nuts represent the inseparable part of machinetool building. The thread lead accuracy ranges in hundredths of millimetres per 1 m. In addition to the undesirable phenomena caused by heat (dilatability) and, e. g., torsional and transverse oscillations, the bending stress of the ball screw is considerably undesirable too. This stress and at the same time behaviour are transferred to the bending stress of the ball screw nut. This has a very harmful influence on setting of the ball screws, when the machine tool is assembled. Using the analysis by means of the FEM method, the paper conducts a survey of deformation issue of the arrangement "machine – ball screw – ball screw nut" during the assembly stage as well as a survey of compensation possibilities and other technical measures determined to limit the undesirable deformations and stress of the ball screw originating already in the manufacturing stage of the machine tool.
Methodology of Geometry Testing and Measuring of Machine Tool Components Having Big Dimensions and their Verification Using the FEM Method
Authors: Novotný Lubomír W. , Učeň Oldřich
Published: January 2016

The paper deals with the issue of geometric precision measuring at large parts (especially at castings having big dimensions) in their manufacturing stage. The large parts of machinetool frames are required to have their geometric tolerances in thousandths of millimetres. The production or cooperation abilities of the particular company must be adapted to these demands and it is also necessary to adapt the company metrological equipment and measuring procedures to them. The standard measuring equipment cannot be used in most cases, because the particular parts are too large. For this reason, it is necessary to search such methods and procedures which enable to perform measuring with the relevant result. It could be considered to use e. g. 3D scanners. Unfortunately, their measuring precision has not reached the required tolerances up to now. For example, the HandyPROBE 3D scanner measures with the precision of 0,022 mm [1].
Determination of Mechanical Properties of Magnesium Alloys and Composites by Small Punch Testing
Authors: Bártková Denisa , Langer Jiří , Dymáček Petr , Válka Libor
Published: January 2016

Tests on miniature samples are increasingly used for the determination of mechanical properties of materials available in small volumes (non-destructive or semi-destructive approach). Small punch testing at constant deflection rate (SPT-CDR) of selected magnesium alloys and composites was performed at room temperature. Mechanical properties (yield strength, ultimate strength) were evaluated from SPT and correlated with results of uniaxial tensile tests (UTT). SPT characteristics were converted to uniaxial tensile properties by empirical formulas available in the literature. New formulas more appropriate for magnesium alloys were suggested.
Comparison of Hybrid Metal-Composite Small-Pin Joints with Conventional Ones in Terms of Static and Fatigue Strength
Authors: Beketova Ganna , Shevtsova Marina , Symonov Volodymyr
Published: January 2016

The current research deals with special hybrid metal-composite joints (MCJ) which use thin sheet-metal reinforcement with small die-fixed pins (2-3 mm) embedded into the composite part of the joint. This technological trick significantly and positively influences strength of the metal-composite bolted joints loaded in out-of-plane direction. This fact was proved by comparison of pull-off static and fatigue tests results of MCJs with and without reinforcement.
Definition of Effective Material Properties of Recycled Plastic: Image Analysis and Homogenization
Authors: Procházková Zdenka , Králík Vlastimil , Doubrava Karel , Šejnoha Michal
Published: January 2016

The influence of foaming agent on the properties of steel-reinforced beams made of recycled plastic material is studied in the paper. The foaming agent creates a porous core in the recycled plastic elements. This core must be reflected when deriving the beam effective properties to be used in macroscopic simulations. To that end, standard image analysis combined with nanoindentation and the Mori-Tanaka micromechanical model is adopted to identify elastic material properties of the plastic material both inside and outside of the core. These are expected to enter an independent macroscopic analysis of the steel-reinforced beams.
Determination of Turning Knife Thermal Stress during Longitudinal Turning
Authors: Stránský Marek , Horský Jaroslav
Published: January 2016

A turning knife contacts a work piece during turning. Due to friction, heat is produced proportionally to the turning speed. The resulting temperature influences the quality of the machined surface and wear of the knife. Thus, new machine tools must be developed that minimize the production of unwanted heat. To accomplish this task, a new experimental knife was prepared with thermocouples both built into it and welded to its surface. The measurement process was supplemented by thermovision. Heat flux and surface temperatures were computed from subsurface data using a one-dimensional inverse relationship. The detailed temperature distribution on the surface of the turning knife was determined using a combination of these methods.
Finite Element Modelling of the Effect of Stiffness and Damping of Vocal Fold Layers on their Vibrations and Produced Sound
Authors: Hájek Petr , Švancara Pavel , Horáček Jaromír , Švec Jan G.
Published: January 2016

The study presents a two-dimensional (2D) finite element (FE) model of the fluid-structure-acoustic interaction during self-sustained oscillation of the human vocal folds (VF). The FE model combines the FE models of the VF, trachea and a simplified human vocal tract shaped for phonation of a Czech vowel [a:]. The developed FE model comprises large deformations of the VF tissue, VF contact, fluid-structure interaction (FSI), morphing of the fluid mesh according to the VF motion (Arbitrary Lagrangian-Eulerian approach), solution of unsteady viscous compressible airflow described by the Navier-Stokes equations and airflow separation during the glottis closure. The effect of stiffness and damping of lamina propria, which can be caused by certain VF pathologies, on VF vibrations and produced sound are analyzed. The numerical simulations showed that stiffer lamina propria results in a decrease of the maximum width of glottal opening and in a decrease of the fundamental vibration frequency. Stiffer lamina propria also leads to an increase of maximum of the subglottal pressure and it causes amplitude decrease and flattening of the first and second formant in the spectrum of acoustic pressures. Higher values of lamina propria damping result in the amplitude decrease and flattening of all formants.
Hot Forming of Mg AZ31B Alloy Sheet Processed by Warm Rolling
Authors: Antoniswamy Aravindha R. , Weldon Andrew J. , Taleff Eric M. , Hector Louis G. , Carter Jon T.
Published: January 2016

Mg alloy AZ31B is of interest for hot forming because it can achieve a superplastic response at high temperatures and slow strain rates. As temperature decreases and forming rate increases, its strain-rate sensitivity decreases and significant plastic anisotropy can arise. These effects are the result of a transition in deformation mechanisms from grain-boundary-sliding (GBS) to dislocation-climb (DC) creep. However, sheet production using warm rolling can produce a material with a smaller grain size and weaker basal texture. These microstructural changes promote GBS creep and decrease the degree of anisotropy under DC creep. Microstructural and tensile data are presented to show these effects at 350 and 450C through comparisons to a similar material having a more usual microstructure.
Deformation Mechanism and Characteristics of Thin-Walled Component in Aluminum Alloy
Authors: Liao Kai , Chen Fei , Liu Yi Peng
Published: January 2016

During milling of thin-walled components, obtaining minimum distortion is essential in order to achieve production goals. In this study, a mechanical model based on deformation machanism is established, and is help to analyse relationship between residual stress and deformation in component. Researched on simulation and experiment, the stress-deformation characteristics of different component shape is obtained. The results indicate that the deformation of thin-walled component in milling primarily depends on the distribution of initial residual stress, which can generate bending moment and lead to distortion. And then milling stress on the surface is easy to make bending moment baesd on this distortion, and make the deformation of component intensify.
Effect of Hydrogen on the Development of Superplastic Deformation in the Submicrocrystalline Ti–6Al–4V Alloy
Authors: Grabovetskaya Galina P. , Stepanova Ekaterina N. , Ratochka Ilya V. , Mishin I.P. , Zabudchenko Olga V.
Published: January 2016

Hydrogenation effect on the development of superplastic deformation in the submicrocrystalline Ti–6Al–4V alloy at temperatures (0.4–0.5)Тmelt is investigated. Hydrogenation of the submicrocrystalline Ti–6Al–4V alloy to 0.26 mass% during superplastic deformation is found to result in solid solution strengthening, plastic deformation localization, and as a consequence, decrease of the deformation to failure. Possible reasons for the decrease of the flow stress and increase of the deformation to failure in the submicrocrystalline Ti–6Al–4V–0.26H alloy during deformation under conditions of superplasticity and simultaneous hydrogen degassing from the alloy are discussed.
Effect of Rolling on Superplastic Behavior of an Al-Mg-Sc Alloy with Ultrafine-Grained Structure
Authors: Dubyna Andrii , Malopheyev Sergey , Kaibyshev Rustam
Published: January 2016

The superplastic behavior of a commercial aluminum alloy denoted as 1570 Al with a chemical composition of Al-6%Mg-0.5%Mn-0.2%Sc-0.07%Zr (in wt. %) and ultrafine-grained (UFG) structure produced by equal channel angular pressing at 300°C to a true strain ~12 was studied after final cold or warm rolling. The tensile specimens were machined along rolling direction and pulled up to failure in the temperature range of 250 to 500°C at strain rates ranging from 10-4 s-1 to 10-1 s-1. The specimens produced by warm or cold rolling exhibit different superplastic behavior. The material subjected to warm rolling exhibits excellent superplastic properties; the highest elongation-to-failure of ~1970% was recorded at a temperature of ~450°C and an initial strain rate of 1.4×10-1 s-1. On the other hand, the material subjected to cold rolling demonstrates moderate superplastic properties; the highest elongation-to-failure of ~755% appears at a temperature of ~300°C and an initial strain rate of 1.4×10-2 s-1.
Effect of Different Proportion of Coarse and Fine Grain Microstructure on Superplastic Forming Characteristics
Authors: Pancholi Vivek , Rohit K. , Raja A.
Published: January 2016

The study was carried out to understand the effect of inhomogeneous microstructure on thickness variation in superplastically formed bulge. Friction stir processing was performed at rotational and traverse speeds of 720rpm and 155mm/min respectively on a 6mm sheet maintaining 50% overlap on the retreating side. Different probe dimensions were selected to obtain different proportions of fine grained stir zone in thickness direction. The proportions of the fine grained stir zone were 25%, 50%, 72% and, 100%. The sheets containing inhomogeneous microstructure were subjected to superplastic bulge forming under constant gas pressure up to a bulge height of 23.5mm. The sheet which was processed with 72% fine grains showed lower thickness variation from edge to apex and the bulge shape in this condition was close to the ideal spherical profile.
Preliminary Identification of Silantek Clay as Potential Refractory
Authors: Seli Hazman , Bujang Japri , Ahmad Zainal Arifin
Published: January 2016

Silantek clay deposits were characterized and evaluated for their potential as structutral ceramic products raw materials through chemical, mineralogical and refractory (1250 to 1600o C) properties determinations. Results show that the main oxides in the samples were SiO2 and Al2O3, whereas the other oxides present only in small quantity. Kaolinite(Al2Si2O5(OH)4) and quartz(SiO2) present as dominant mineral phases and the minor phases of mullite(Al6Si2O13) and zeolite(Na2Al2Si3O10·2H2O) also appeared in the samples. From the results of the refractoriness tests up to 1600°C, samples ST11, ST23A, ST31A, ST31B, ST33 have potential for refractory products as they demonstrated high thermal resistance properties(over 1600°C). Silantek clay potential to be used as raw materials mainly for refractory, structural ceramics and other common ceramic products
Crystallite Size Measurement of Doped CaCu2.8Co0.2Ti4O12 Ceramic Samples Using Various Method
Authors: Johar Banjuraizah , Ahmad Zainal Arifin
Published: January 2016

CaCu2.8Co0.2Ti4O12 ceramics were prepared by microwave-assisted sol gel method. The properties of materials can be highly dependent on crystallite size therefore measuring the crystallite size is among the important part in materials research work. In the present study, the crystallite size of the CaCu2.8Co0.2Ti4O12 ceramics sintered at temperature ranged from 975-1125°C were investigated. Different methods, approach and strategy of crystallite size measurement were demonstrated in this papers.Keywords: Crystallite size, CCTO
Effect of Current Density on Anodised Titanium in Sulphuric Acid for Biomedical Application
Authors: Selimin Mohamad Ali , Idris Maizlinda Izwana , Abdullah Hasan Zuhudi
Published: January 2016

Bioinert titanium (Ti) can be modified to bioactive by performing various techniques including anodic oxidation. Where, this method encompasses electrode reactions in combination with electric field driven metal and oxygen ion diffusion to the formation of an oxide film on anode surface. The objective of this study is to evaluate the effect of current density of anodic oxidation upon the characteristic of titanium in sulphuric acid (H2SO4) under various conditions. The modified titanium was prepared using anodic oxidation method in 0.3 M of sulphuric acid as electrolyte. The applied voltage and current density of the anodic oxidation parameters were varied from 50 – 200 V and 25 – 75 mA.cm-2 respectively for 10 min of oxidation process at room temperature. The effects of anodic oxidation on the titanium were characterised using X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The results show that by increasing the current density of the anodic oxidation, different mineralogy, surface morphology, and surface profile were produced. At low current density (25 mA.cm-2), high voltage is needed to produce high crystalline of anatase formed on the titanium surface and only able to produced very low of rutile titanium with 200 V of applied voltage compared to high current density (75 mA.cm-2) with same applied voltage, very high rutile crystal with mixture of low anatase was observed on the titanium. This modified oxide of titanium has potentially to be applied in biomedical as implant.
On Using Factorial Fractional Design to Fabricate Porous Alumina Scaffolds for Bone Tissue Engineering (BTE)
Authors: Shahabudin Nor Suhaida , Ahmad Zainal Arifin , Abdullah Norazharuddin Shah
Published: January 2016

The porous scaffold has a weakness in terms of compressive strength. This is due to the porosity that is inversely proportional to the strength of the porous scaffold. Greater the percentage of porosity will decreasing the compressive strength. However, this compressive strength can be improve by controlling several factors (i.e., number of PU pores, composition ratio of slurry, percentage of binder and number of coating process). In general, fabrication porous alumina by conventional process was takes a longer time and consuming high cost. In addition, the conventional process could not explain the interaction relationship between all factors. Therefore, experimental design using Minitab 16 is applied to investigate the factors’ interaction. From the analysis, a combination of composition ratio and number of coating were found to have a significant impact to increase the compressive strength (> 2MPa) while others are less significant.
Modification of Rubber Particles and Ceramic Fillers on PMMA Denture Base Materials
Authors: Alhareb Ahmed Omran , Md Akil Hazizan , Ahmad Zainal Arifin
Published: January 2016

The purpose of this study is to investigate the effect of nitrile butadiene rubber (NBR) particles and ceramic fillers on the density of PMMA denture base materials. The denture base was prepared based on the mixture of PMMA powder and MMA liquid. The density of the denture base has been modified by adding three different ratios of nitrile rubber (5, 7.5 and 10 wt %), three types of ceramic fillers (Al2O3, YSZ and SiO2, respectively) fixed at 5 wt %, 0.5% of benzoyl peroxide (PBO) and ethylene glycol dimethacryate (10 wt% EGDMA). The powder/liquid (P/L) was mixed by 2.5:1 g ratio. At 10 wt% of NBR the denture base density has reduced to 50%. Furthermore, the addition of ceramic fillers together with NBR particles has also reduced the denture base density. The density data was statistically analysed by on-way (ANOVA) and the values were significantly effect when addition of rubber particles in PMMA denture base composite (p < 0.05).Therefore, the density issue can be easily adjusted in retention and stability of denture base in the patient mouth.
The Formation of Cobalt Chromium Molybdenum (CoCrMo) Foams Fabricated by Slurry Method
Authors: Ahmad Sufizar , Rosli M. , Abdul Manaf Nur Suliani , Mahammad Rafter Murni Faridah , Mat Noor Fazimah
Published: January 2016

Cobalt Chromium Molybdenum (CoCrMo) is a metal that are widely used in the biomedical field of orthopedic applications. CoCrMo foam was developed in the form of a porous structure where it has a high porosity on the surface with the different pore sizes and shapes. This research is intended to produce CoCrMo foam by using slurry method and to study the effect of composition and sintering temperature on the metal foams. The slurry of CoCrMo was prepared by mixing the binder materials of Methylcellulose (CMC), Polyethylene Glycol (PEG) and distilled water for an hour. Followed by mixing and stirring the CoCrMo powder for another 1 hour until it becomes slurries. Polyurethane (PU) foam was then impregnated into the slurry and dried for a day in the oven with 60 °C. Sintering process is carried out at temperature of 1000 °C, 1100 °C and 1200 °C using a tube furnace. Then sample of CoCrMo foam was going through a shrinkage measurement, microstructure analysis by using Scanning Electron Microscope (SEM), analysis of element by using Energy Diffraction X-ray (EDX) and also the density and porosity test by using Archimedes method. The sample with the composition of 65wt% was the best result in this experiment. While sintering temperature of 1200 °C produced the highest number of porosities. The shrinkage percentage is from 2.67% to 14.13%. The density obtained is in between 1.538 g/cm3 and 2.706 g/cm3 while the percentage of porosity is from 50.284% to 78.934%. The average pore size is in the range of 249.63μm to 445.38μm. The best sintering temperature and composition to produced high porosity were on 1200 °C and 65wt%.
Characterization of Cordierite Glass with the Addition Colorant Ceramic Glaze for FIR Therapy
Authors: Yi Xuan Lim , Johar Banjuraizah , Ahmad Zainal Arifin
Published: January 2016

α-Cordierite glass ceramic was synthesised through crystallization of glass compacts made of milled glass frits. The effect of temperatures and colorants were studied. The crystal structure of α-cordierite was analysed using X-ray diffraction technique and Rietveld structural refinement method. Density, porosity and shrinkage analysis, Vickers hardness and SEM were also performed. The result revealed that at higher sintering temperatures, the properties of α-cordierite was getting better. Low apparent porosity level and high hardness dense α-cordierite was fabricated at temperature 1350oC. The low porosity level may lead to high thermal conductivity which suggested that cordierite was candidates for FIR therapy instrumemts.________________________________________________________________________
Electrochemical Synthesis and Characterisation of BiTe-Based Nanowire Arrays as Thermoelectric Nanogenerators
Authors: Kok Kok Ying , Ng Inn Khuan , Choo Tan Foo , Saidin Nur Ubaidah , Abdullah Yusof
Published: January 2016

Thermoelectric (TE) nanogenerators are solid state devices that can directly convert thermal energy into electrical power. The family of bismuth telluride (BiTe)-based semiconductor materials is a good candidate for room-temperature thermoelectric applications. This work aims to synthesize the binary and ternary TE nanowire arrays from BiTe and BiSbTe using template-assisted electrochemical deposition. The compositions and lengths of the nanowires fabricated were precisely tuned by controlling the deposition conditions, while their diameters were confined by the pore sizes of the anodized alumina oxide (AAO) templates used. Chemical compositions of the nanowires were evaluated using Energy Dispersive X-ray (EDX) Spectroscopy and their microstructures were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), conventional transmission electron microscopy (CTEM) and high resolution transmission electron microscopy (HRTEM). TE nanogenerator modules comprising of BiTe and BiSbTe nanowires/AAO composite arrays were fabricated for TE performance evaluation on the basis of their power outputs.
Standardless EDXRF Analysis Methods of U and Th in Malaysian Tin Slag Waste
Authors: Meor Sulaiman Meor Yusoff , Kamaruzaman Nursaidatul Syafadillah , Zahari Ahmad Khairulikram
Published: January 2016

Accurate quantification of uranium and thorium elements was performed in the absence of standards for the XRF analysis. This quantification method uses standard addition method. The standard addition method was first established by performing a micofocus XRF onto a sample. In the calibration graphs of uranium, the R2 was 0.9997 white the R2 value for thorium was 0.9915. Once the baseline quantity of both uranium and thorium were obtained, they were used to normalize all the quantification of other samples prepared by grab and vibratory methods. It was found out that the vibratory method gives more accurate results.
CTAB-Assisted Precipitation Synthesis of Ca(OH)2 Sorbent for CO2 Captures
Authors: Mohd Daud Farah Diana , Sreekantan Srimala , Mohamed Abdul Rahman
Published: January 2016

Ca (OH)2 sorbent with novel pods bundle structure were successfully synthesized by precipitation method by using Cetyltrimethylammonium bromide (CTAB) as cationic surfactant. The effects of CTAB on the morphologies of Ca (OH)2 sorbent were investigated. The results showed that the presence of CTAB could significantly differ the shape and particle size of the Ca (OH)2 sorbent which synthesized in ethanol media at 35°C for 30 minutes. The XRD pattern indicated that the as-prepared product were well-crystallized hexagonal phase of Ca (OH)2 sorbent. Possible mechanisms for the CTAB assisted particle growth of Ca (OH)2 sorbent are discussed. The Ca (OH)2 sorbent have been studied by thermal gravimetric analyzer (TGA) at a 650oC carbonation temperature. The morphological changes and particle size of the sorbent have greatly influenced the CO2 capture performance.
Treatment of Oily Waste Using Activated Carbon from Agriculture Waste
Authors: Koo Wai Kit , Sulaiman Muhammad Azwadi , Subki Noor Syuhadah , Mohamed Mazlan , Masri Mohamad Najmi , Abu Bakar Mohamad Bashree , Mohamad Amini Mohd Hazim , Nik Yusuf Nik Alnur Auli
Published: January 2016

Malaysia is one of the main crude oil exporters among countries in Association of South East Asian Nations, ASEAN. Therefore, oil is widely used in many sectors, especially in transportation sectors, and it will produce a lot of oil-based waste that will harm environment. Activated carbon can help to treat this waste by using the permeable reactive barrier (PRB) concept. At the same time, Malaysia is also an agricultural based country which produces a massive amount of agricultural waste. In this study, sugarcane bagasse, corn cob and pineapple's core is chosen to produce activated carbon by using furnace heating processing and microwave processing.
Synthesis and Characterization of Colorant Glass and Glass Ceramic from Non Stoichiometric Cordierite Composition with the Addition of Colorant Material at Different Temperature
Authors: Abdullah Nurain , Johar Banjuraizah , Ahmad Zainal Arifin
Published: January 2016

Cordierite glass of non stoichiometric (2.8MgO 1.5Al2O3 5SiO2) can be used to synthesis the synthetic gems because of it properties. The colorant glaze material; 2% , which from trace element cam give colorant to cordierite glass sample. The XRD analysis give result that α-cordierite formed at temperature 1250°C. The density and porosity of cordierite glass decreased as the sintering temperature increased. The hardness from Vickers Hardness are increased as the sintering temperature incerased.
Role of Ce2Zr3O10 Phase on the Microstructure and Fracture Toughness of ZTA Composites
Authors: Rejab Nik Akmar , Sktani Zhwan Dilshad Ibrahim , Mohd Ali Afifah , Ahmad Zainal Arifin
Published: January 2016

Despite the impressive development in understanding transformation toughening, tailoring the toughness of zirconia toughened alumina (ZTA) ceramics remained a major challenge. In our research, a simple route based on the powders mixing process of ZTA powders with varying CeO2 additions (0 - 10 wt.%) is developed to investigate this issue. The experimental results clearly reveal that the fracture toughness of ZTA ceramics can be tailored by mixing of ZTA starting powders.
Synthesize CCTO Using Different Mixing Media
Authors: Zaman Rosyaini Afindi , bin Abu Mohamad Johari , Abdul Karim Saniah , Mohamed Julie Juliewatty , Ain Mohd Fadzil , Ahmad Zainal Arifin
Published: January 2016

In recent years, there has been an increasing interest on high dielectric constant that have significant applications in electronic devices. Dielectric materials have many technological applications such as capacitors, resonators and filters. High dielectric ceramic capacitors based perovskite oxides are necessary for modern electronic devices and are found to be suitable for a wide range of applications. Subramanian et al. discovered the high dielectric constant of CaCu3Ti4O12 (CCTO) ~ 10,000 at room temperature. CCTO has the cubic perovskite crystal structure and high dielectric constant of ~ 104 up to 105 at radio frequency and good temperature stability over a wide temperature range [1,2]. These properties were desired for various microelectronic applications. With the high dielectric constant, the material can store more charge and the values make CCTO an attractive material for ultra-high energy density capacitors. However, this properties can be accomplished if single phase of CCTO is formed. Many research have been done recently on the synthesis of the cubic perovskite CCTO and many techniques are working such as sol-gel route [3], combustion techniques [4], molten salt process [5] and etc., but this technique is difficult and complex process during sample preparation.
Preparation of Nickel Oxide-Samarium-Doped Ceria Carbonate Composite Anode Powders by Using High-Energy Ball Milling for Low-Temperature Solid Oxide Fuel Cells
Authors: Hoa Ng Kei , Rahman Hamimah Abdul , Rao Somalu Mahendra
Published: January 2016

The characteristics of the starting powder in powder preparation method are important for enhancement of cell performance. In this study, the composite anode powders of NiO–samarium-doped ceria carbonates (SDCC) were prepared by using different NiO loadings (50–70 wt.%) via high-energy ball milling. The composite anode powders were ball-milled in ethanol at a milling speed of 550 rpm. The obtained NiO–SDCC composite anode powders were characterized by XRD, FTIR, FESEM, and EDS. Results indicate that the composite anode powders demonstrated good chemical compatibility between NiO and SDCC, given that no new phases were detected in the XRD analysis. FTIR spectra confirmed that the composite anode powders contain carbonates in amorphous state after high-energy ball milling. FESEM investigation revealed well-distributed fine particles and significant reduction of particle size at nanoscale compared with the powder prepared using NiO particles as the starting material. EDS mapping verified the homogeneity of the composite powder with good elemental distribution. Thus, high-energy ball milling is an effective method to prepare NiO–SDCC composite anode powders within a relatively short processing time.