bluuebunny/crossref_metadata_2025 huggingface dataset:
Timber-Lightweight Aggregate Composite Floor Structure
Authors: Haiman Miljenko , Turčić Nenad
Published: November 2012

Nowadays, composite structures based on wood are frequently used. In civil engineering, mostly timber-concrete composite structures are used, particularly in reconstruction of old timber girder floor structures or manufacture of new ones at the reconstruction of old buildings in areas exposed to frequent earthquakes. In new buildings it is mainly glued laminated timber or lumber, while in reconstruction square timber is used. A timber beam is coupled with a concrete slab made either of conventional or a lightweight concrete. Best results are achieved by coupling timber with lightweight aggregate concrete that has all the properties similar to the timber except for its strength that is much higher and comparable to that of conventional concrete. This paper analyzes a composite timber-lightweight aggregate concrete structure. The basic girder is a T-cross section, with the web made of glulam, and flange made of lightweight concrete with expanded clay aggregate (Liapor). The two materials are coupled by means of mechanical fasteners, allowing joint action of the composite section. Quality of coupling has been determined by experimental tests carried out at the Laboratory of the Technical Mechanics Institute, Faculty of Civil Engineering in Zagreb. Finite element method was used for modelling of composite structures using ABAQUS software. The aim of this study was to determine the advantages of using timber-lightweight aggregate concrete composite structure, compared to solutions in which timber-conventional concrete composite structure or reinforced concrete slab are used.
Integrated Application of RP and FEM to Support "One of a Kind" Component Design Using Prototyped Materials
Authors: Pasquali Felipe Meneguzzo , Bareta Deives Roberto , Corso Leandro Luis , Costa Carlos Alberto
Published: November 2012

This paper discusses the integrated use of rapid prototyping commercial technology and finite element method to support design of engineering components. The study was carried out on PolyJet RP technology. The resin properties were investigated by standard tests (ASTM) and used as input data on Abaqus software application. The results of the physical test were used to calibrate and validate the finite element model. Experimental tests were executed capturing critical loads and main forces acting on the geometric model and compared with the virtual model. The results showed small percentage differences between the physical and virtual models. Viscoelasticity of the resin was also detected in the analyzed physical model. Initial results have shown that the integration of these two technologies can assist in developing functional products, considering the technical limitations of the current prototype materials.
The Dang Van Criterion for Fatigue Design
Authors: Peixoto Daniel F.C. , Ferreira Luis A.A. , de Castro Paulo M.S.T.
Published: November 2012

The present work intends to evaluate, using simple, exemplary cases, the importance of a full elasto-plastic analysis in fatigue design. A strain cycling situation (-ε to ε) was modelled with ABAQUS considering two situations: firstly a linear σ vs. ε relationship was assumed, and secondly, the real cyclic σ vs. ε curve was used to model each cycle, which includes a small plastic deformation. The case of change of cross section in a steel shaft subjected to constant torsion and cyclic bending was analysed through finite element modelling using ABAQUS.
Arsenic Removal via Cellulose-Based Organic/Inorganic Hybrid Materials from Drinking Water
Authors: Martins Catarina , Duarte Rui F. , Magalhães Maria C.F. , Evtuguin Dmitry
Published: November 2012

Cellulose/silica derived hybrids materials (CSH), functionalized with aluminium, calcium, and propylammonium ions, were tested for their possible use in the removal of arsenic from aqueous solutions with controlled compositions to levels lower than 10 μg As/L. CSH were synthesized by sol-gel method using bleached pulp, as source of cellulose fiber, and tetraethoxysilane (TEOS) as main silica precursor. The silica network, made in situ, contained various anchored cations such as propylammonium (CSH-PA), aluminium (CSH-Al) and, calcium (CSH-Ca). Thin films or mesoparticles of silica were deposited on cellulose fibers as shown by SEM and XRD. These hybrid materials were immersed in controlled ionic strength aqueous solutions with arsenic concentrations lower than 0.2 mg As/L. The best performance was shown by CSH-PA that was able to remove a maximum of 20 % of the total arsenic concentration.
Embodied Energy versus Operational Energy. Showing the Shortcomings of the Energy Performance Building Directive (EPBD)
Authors: Pacheco-Torgal F. , Faria Joana , Jalali Saíd
Published: November 2012

Energy is a key issue for Portugal, it is responsible for the higher part of its imports and since almost 30% of Portuguese energy is generated in power stations it is also responsible for high CO2 emissions. Between 1995 and 2005 Portuguese GNP rise 28%, however the imported energy in the same period increased 400%, from 1500 million to 5500 million dollars. As to the period between 2005 and 2007 the energy imports reach about 10,000 million dollars. Although recent and strong investments in renewable energy, Portugal continue to import energy and fossil fuels. This question is very relevant since a major part of the energy produced in Portugal is generated in power plants thus emitting greenhouse gases (GHGs). Therefore, investigations that could minimize energy use are needed. This paper presents a case study of a 97 apartment-type building (27.647 m2) located in Portugal, concerning both embodied energy as well as operational energy (heating, hot water, electricity). The operational energy was an average of 187,2 MJ/m2/yr and the embodied energy accounts for aprox. 2372 MJ/m2, representing just 25,3% of the former for a service life of 50 years. Since Portuguese energy efficiency building regulation made under the Energy Performance Building Directive (2002/91/EC-EPBD) will lead to a major decrease of operational energy this means that the energy required for the manufacturing of building materials could represent in a near future almost 400% of operational energy. Replacement up to 75% of Portland cement with mineral admixtures could allow energy savings needed to operate a very high efficient 97 apartment-type building during 50 years.
Kinetic Study of Thermal De-Chlorination of PVC-Containing Waste
Authors: Castro Alexandra , Vilarinho Cândida , Soares Delfim , Castro Fernando
Published: November 2012

The presence of organic compounds on wastes, especially plastics, is considered an important source of energy. However, most of these plastics contain polyvinyl chloride (PVC), causing recycling problems when it is considered a thermal valorization process for its treatment [1], preventing the use of those residues on these processes, which main goal is the energy recovery [2,3]. A possible solution is to remove the chlorine from PVC containing waste through a pyrolysis process before being subjected to a thermal treatment, for energetic valorization. In this work, it was developed a kinetic model for the thermal decomposition of PVC, in view of its de-chlorination. DTA/TGA testing were performed at different temperatures (between the range of decomposition temperatures of the PVC molecule) indicated a first order reaction and an activation energy of 133800 J/mol, value very close to the one obtained in others works reported [4]. A factorial plan was carried out with different temperatures, performed in lab scale, in which best results were obtained at the temperature of 340 °C, proving the kinetic model obtained.
Performance Assessment of Waste Fiber-Reinforced Mortar
Authors: Gonilho-Pereira Cristiana , Faria Paulina , Fangueiro Raul , Martins Ana , Vinagre Pedro , Ratão Sofia
Published: November 2012

In this paper an experimental work is presented which main objective is the evaluation of the influence of different percentages of waste fibrous materials usage on the performance of fiber-reinforced mortars. Moreover, the influence of binder type is evaluated. Therefore mortars were produced with two different binders – cement and powder hydrated lime. Mortars performance evaluation was carried out through flow table and plunger penetration consistency, dynamic modulus of elasticity, flexural and compressive strength, capillary absorption, drying index and adherence tests. The benefits revealed in some characteristics of both mortars by the use of waste fibers are discussed.
Technical Aspects of Adsorption Process onto an Innovative Eggshell-Derived Low-Cost Adsorbent
Authors: Carvalho Joana , Ribeiro André , Araújo Jorge , Castro Fernando
Published: November 2012

As the current global trend towards more stringent environmental standards, technical applicability and cost-effectiveness became key factors in the selection of adsorbents for water and wastewater treatment. Recently, various low-cost adsorbents derived from agricultural waste, industrial by-products or natural materials, have been intensively investigated. In this respect, the eggshells from egg-breaking operations constitute significant waste disposal problems for the food industry, so the development of value-added by-products from this waste is to be welcomed. The egg processing industry is very competitive, with low profit margins due to global competition and cheap imports. Additionally, the costs associated with the egg shell disposal (mainly on landfill sites) are significant, and expected to continue increasing as landfill taxes increase. The aim of the present review is to provide an overview on the development of low-cost adsorbents derived from eggshell by-products.
The Effect of Shredding and Particle Size in Physical and Chemical Processing of Printed Circuit Boards Waste
Authors: Oliveira Paula C. , Taborda Filipa Charters , Nogueira Carlos A. , Margarido Fernanda
Published: November 2012

Circuit boards present in most electric and electronic devices are very important components, which should be removed during sorting and dismantling operations in order to allow further adequate treatment for recovering valuable metals such as copper, nickel, zinc, lead, tin and rare elements. This recovery can be made by physical and chemical processes being size reduction by shredding the first step. In this paper, the effect of particle size in physical and chemical processing of printed circuit boards is presented and discussed. Shredding using cutting-based equipment allowed the comminution of boards and the liberation of particles composed by different materials (mainly metals and resin). Particle sizes less than 1 mm seems to be appropriate to attain high liberation of materials, which is crucial for the physical separation using gravity or electrostatic processes. Concerning chemical treatment, hydrometallurgical processing involves a leaching operation which can be also influenced by particle size of shredded boards. Samples with different granulometries were leached with 1 M HNO3 solutions, being leaching yields evaluated. It was concluded that particle size can be an important factor for the solubilization of some metals, but the effect is not similar for all elements. When average diameters change from 2.0 to 0.20 mm, nickel, aluminium and tin reactivity were not significantly affected, being this effect important for copper. Zinc behavior was very dependent from extreme particle sizes but was less affected in intermediate granulometries. Lead leaching showed also a peculiar behavior, exhibiting high and almost constant yields (80-90%) for particle size of solids up to 1.2 mm, and decreasing suddenly for higher granulometries. The effect of time on chemical reactivity for samples with different granulometries demonstrated that particle size affects reaction rates but eventually similar efficiencies can be obtained for long time periods. Therefore the relationship between results from shredding operation and chemical leaching step needs to be optimized, considering the balance between factors like consumption of energy during grinding operation and residence time in leaching.
A Fatigue Study of C-130 Aircraft Skin Using the Stop Drill Technique
Authors: Cardoso José A.S. , Infante Virgínia , Serrano Bruno A.S.
Published: November 2012

The stop-drilling technique is a simple and economic way to delay crack propagationby drilling a hole on the crack tip and reducing stress concentration. This paper presents thepropagation of cracks and investigates how the increasing of the stop-drill diameter improvescrack initiation life in specimens of 2024-T3 aluminium alloy of C-130 aircraft skin. A numericalmethod was applied to simulate an automatic crack propagation by interacting ANSYSr andMATLABr, and several experimental fatigue tests were done to support the computationalresults. A Morrow equation was used to predict the fatigue life of the stop-drill. Good agreementof stress intensity factor along crack length was obtained between numerical and experimentalresults. All results show that fatigue life increases when the stop-drill diameter is larger. Whencompared to the 2mm diameter stop-drill, the experimental results show an improvement of189% and 464% to 4mm and 6mm diameter stop-drill fatigue life, and the numerical results of333% and 952%, respectively.
A Three-Stage Explicit Stress-Strain Relations for Stainless Steel Alloys Applicable in Tension and Compression at Elevated Temperatures
Authors: Kenzu Abdella
Published: November 2012

Presented in this paper is an explicit full-range stress-strain relation for stainlesssteel alloys applicable at normal and elevated temperatures. The relation utilizes an approxima-tion of the closed form inversion of a highly accurate three-stage stress-strain relation recentlyobtained from the Ramberg-Osgood equation. The three stage inversion is formulated using anappropriate rational function assumption to approximate the fractional deviation of the actualstress-strain relation from an idealized linear elastic behaviour. The temperature dependenceon the stress-strain relation is then introduced by modifying the basic mechanical propertiesof stainless steel to account for the temperature e ects. The proposed approximate inversionis applicable over the full-range of the stress well beyond the elastic region up to the ultimatestress. Moreover, the inversion can be applied to both tensile and compressive stresses. Theproposed approximate inversion is tested over a wide range of material parameters as well as awide range of temperatures. It is shown that the new expression results in stress-strain curveswhich are both qualitatively and quantitatively in excellent agreement with experimental re-sults and the fully iterated numerical solution of the full-range stress-strain relation for normalas well as elevated temperatures
Analysis and Evaluation of Shape Memory Alloy Wires Behaviour in Weft-Knitted Fabrics
Authors: Medeiros Jose Ivan , Fangueiro Raul
Published: November 2012

It is widely acknowledged within the textile engineering community that Shape Memory Alloys (SMA), exhibit great potential for several applications. This paper presents the research undertaken at the University of Minho aiming to study the behaviour of weft-knitted fabrics produced with SMA nitinol® wires. SMA nitinol® wires of type B (which shows shape memory effect at body temperature) of 50, 127 and 210 µm diameters have been used to produce weft-knitted fabrics with different loop types, e.g. stitch, tuck and miss. The influence of the loop type on the performance of the weft-knitted fabric, in terms of energy absorption, has been analyzed. Tensile tests were carried out according to ISO1462 standard, using a H100KS Hounsfield universal testing instrument. The results aim to help future applications of SMA in the development of new textile materials.
Effect of Boron on the Amorphization of Fe-Si Alloys by Mechanical Alloying
Authors: Urban Petr , Cuevas Francisco G. , Martos Juan Manuel Montes , Cintas Físico Jesus
Published: November 2012

The amorphization process by mechanical alloying in the Fe-Si alloy system has been studied. High energy ball milling has been applied for alloys synthesis. X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to monitor the structural and phase transformations through the different stages of milling. The addition of amorphous boron in the milling process and the increase of the milling time were used to improve the formation of the amorphous phase. Heating the samples resulted in the crystallization of the synthesized amorphous alloys and the appearance of equilibrium intermetallic compounds.
Heat Transfer Characteristics of Inward, Outward and Upward Solidification of an Al-1.5wt%Fe Alloy in Cylindrical Chill Molds
Authors: Bertelli Felipe , Meza Elisangela dos Santos , Bezerra Debora de Jesus , Goulart Pedro R. , Cheung Noé , Garcia Amauri
Published: November 2012

In this work, three water-cooled experimental solidification devices were developed, and experiments were carried out with an Al-1.5wt%Fe alloy. The three experimental setups consist of vertical cylindrical steel molds with each of them having different zones cooled by water. For the inward solidification, a cooled tube is used having its upper and bottom part thermally insulated. For the outward solidification, a cooled tube, forming an inner part, is concentrically placed inside a cylindrical mold, which is thermally insulated from the environment, by using insulating materials. For the upward solidification, the bottom part of the mold is water-cooled and consists of a thin (3 mm) disc of carbon steel, whilst the cylindrical surface is covered with insulating material to avoid lateral heat losses. A numerical solidification model based on the finite difference method is applied for the simulation of the three aforementioned cases of solidification from the chilled surface considering transient heat flow conditions. Experimental thermal readings in the castings have been used for the determination of the transient overall metal/coolant heat transfer coefficient, h, through a numerical-experimental fit of casting thermal profiles based on inverse heat transfer calculations. It was found a significant variation of h as a function of time during solidification in the three cylindrical set-ups experimentally examined, including a remarkable increase in h during the outward solidification. Introduction
Influence of Additional Alloying Elements on Corrosion Resistance of Hot Dip Galvanised Steels
Authors: Alexa Alexandru , Radu Tamara , Potecasu Florentina , Ciocan Anisoara
Published: November 2012

The alloying of the zinc with some additional elements in specific quantities could be reliably used in the hot-dip coating process. These elements form specific intermetallic compounds that conferred substantially improved performance to the end-product specially by improving of the corrosion resistance. The paper presents the research that has developed to analyze the influence of aluminum, bismuth and tin like alloying elements added in the zinc on corrosion resistance of galvanized steels. Steel samples were galvanized by the hot-dip method in micro-alloyed zinc baths. The influence of the alloying elements on the formation of the different phases and on the diffusion process is discussed. The corrosion experiments were carried out in a simulated environment of accelerated corrosion conditions. The kinetics and the mechanism of corrosion of the samples were studied in correlation with the effect of alloying elements on nature and characteristics of protective layers.
SMA (NiTi): The Coupling between Time, Temperature and Cycling Frequency
Authors: Torra Vicenç , Auguet Carlota , Isalgue Antonio , Carreras Guillem , Lovey Francisco C.
Published: November 2012

The main interest focuses in the necessary tools for accurate simulation of the damper behavior in their application. It’s essential a well determined knowledge of the dissipated energy and of the hysteresis cycle shape for a correct simulation. The self-heating effects and the coupling between hysteresis and the relevant temperature effects associated to continuous cycling were studied. In particular, the experimental analysis concentrates in the action of cycling frequency on the hysteresis width and on the dissipated energy. The external and the self-heating temperature effects were studied. In particular, the convective actions of cooling in the conditioned air were visualized. The study of self-heating actions at extremely slow cycles, built by strain steps, shows minor latent heat dissipations in the entire sample. For trained samples, the temperature measurements establish that the transformation is “distributed” not “localized” in the complete sample.
The Application of Computational Thermodynamics for the Determination of Surface Tension and Gibbs-Thomson Coefficient of Aluminum Ternary Alloys
Authors: Jácome Paulo A.D. , Moutinho Daniel J. , Gomes Laercio G. , Garcia Amauri , Ferreira Alexandre F. , Ferreira Ileao L.
Published: November 2012

Casting simulation requires high quality information about the thermophysical properties of the alloy, but the number of alloys for which such information is available is limited. In this paper, a solution of Butler’s formulation for surface tension is presented for Al-Cu-Si ternary alloys and consequently, permitting the Gibbs-Thomson coefficient to be determined. The importance of the Gibbs-Thomson coefficient is related to the reliability of predictions furnished by predictive microstructure growth models and of numerical computations of solidification thermal variables, which will be strongly dependent on the values of the thermophysical properties adopted in the calculations. The Gibbs-Thomson coefficient for ternary alloys is seldom reported in the literature. A numerical model based on Powell hybrid algorithm and on a finite difference Jacobian approximation was coupled with a ThermoCalc TCAPI interface to assess the excess Gibbs energy of the liquid phase, permitting the surface tension and Gibbs-Thomson coefficient for Al-Cu-Si hypoeutectic alloys to be calculated. The computed results are presented as a function of the alloy composition.
Unsteady-State Directional Solidification of a Hypoperitectic Pb-9.5wt%Bi Alloy
Authors: Castanho Manuel Antonio Pires , Goulart Pedro R. , Cheung Noé , Garcia Amauri
Published: November 2012

Although considerable attention has been paid to studies on the unidirectional solidification of peritectic alloys, most of these investigations are carried out under steady-state solidification, where both the growth rate and the thermal gradient can be independently controlled and held constant in time. In this work, a hypoperitectic Pb-9.5wt%Bi alloy was directionally solidified under unsteady-state heat flow conditions and the microstructure evolution was analyzed. Continuous temperature measurements in the casting were monitored during solidification, using a data acquisition system and a bank of six type J thermocouples positioned along the casting length. Thermal parameters such as the growth rate (v) and the cooling rate () were experimentally determined by the experimental cooling curves. The solidification microstructure was characterized by a dendritic morphology along the entire casting length. The primary (l1) and secondary (l2) dendrite arm spacings were measured and experimental growth laws relating them to the solidification thermal parameters v and are proposed.
Use of Acoustic Energy in the Processing of Molten Aluminium Alloys
Authors: Puga Hélder , Costa Sónia , Barbosa Joaquim , Pinto Ana M.P. , Ribeiro Carlos Silva
Published: November 2012

During the last years aluminium alloys have been gaining increased acceptance as structural materials in the automotive and aeronautical industries, mainly due to their light weight, good formability and corrosion resistance. However, improvement of mechanical properties is a constant in research activities, either by the development of new alloys or by microstructure manipulation. This presentation focuses a novel effective dynamic methodology to perform microstructural refinement / modification and degassing of light alloys, namely aluminium alloys, by applying acoustic energy to the melts. High intensity acoustic energy significantly improves the microstructure, therefore the mechanical properties of those alloys, avoiding the use of traditional chemically based degassing and refining techniques which are less effective and present significant environmental impact. Ultrasonic (US) vibration has proven to be extremely effective in degassing, controlling columnar dendritic structure, reducing the size of equiaxed grains and, under some conditions, producing globular grains and modifying the eutectic silicon cells in Al-Si alloys. The mechanisms of US processing of aluminium melts are discussed and experimental results on this field are presented.
Carbon Nanofibers Synthesized from Electrospun Cellulose for Advanced Material Applications
Authors: Naboka Olga , Rodriguez Katia , Toomadj A. Farshad , Sanz-Velasco Anke , Toriz Guillermo , Lundgren Per , Enoksson Peter , Gatenholm Paul
Published: November 2012

Carbon nanofibrous sheets (conductivity 1.9 to 35.5 S×cm-1, water contact angle up to 137°) consisting of amorphous fibers with diameter of 20 – 150 nm (C:O atomic ratio 25.4 – 86.0) were synthesized by carbonization of cellulose regenerated from electrospun cellulose acetate mats with three methods of alkaline deacetylation. It was established that C:O atomic ratio, conductivity and hydrophobicity depended on the regeneration method and on the temperature of carbonization. The highest flexibility, lowest conductivity and lowest water contact angle was observed for carbon synthesized from cellulose regenerated with NaOH in ethanol (0.05 mol/l) for 24 hours at room temperature. The highest conductivity, highest water contact angle and lowest flexibility was observed for carbon synthesized from cellulose regenerated with water solution of NaOH/NaCl (3.75 M NaOH, 2.1 M NaCl) during 15 minutes at 65°C.
Natural Nanomaterials: Reappraising the Elusive Structure of the Nano-Sized Mineral Ferrihydrite through X-Ray Absorption Spectroscopy at the Iron K-Edge
Authors: Figueiredo Maria Ondina , Silva Teresa P. , Veiga Joao P.
Published: November 2012

Ferrihydrite is natural ferric oxyhydroxide occurring exclusively nanocrystalline. With ideal formula 5 Fe2 O3 . 9 H2 O, ferrihydrite is quite abundant in sediments, weathering crusts and mine wastes, being characteristic of red pre-soils formed by loose weathered rock plus mineral debris (regoliths) and commonly designated as “2-line” or “6-line” on the basis of the broadened maxima observed in the X-ray diffraction pattern. Synthetic nanocrystalline “6-line” ferrihydrite was recently studied through methods based on atomic-pair distribution functions disclosing the possible occurrence of icosahedral clusters formed by twelve octahedra centred by an inner tetrahedron, all filled by Fe 3+ ions. However, Mössbauer studies were inconclusive about the existence of 4-coordinated iron, thus suggesting that the tetrahedral cation may well be Si4+. In view of such structural uncertainty, a XANES study at the Fe K-edge was undertaken on ferrihydrite from a regolith to ascertain the occurrence of tetrahedral iron. Comparison with data collected from well crystallized iron oxide and hydroxide minerals where Fe 3+/2+ ions occur in octahedral and tetrahedral coordination is described and the results so far obtained are discussed, showing that supplementary study is needed on the elusive structure of ferrihydrite.
Order Effect of Vacuum and Ammonia Atmospheres on Aluminium Nitriding by Mechanical Alloying
Authors: Sánchez Caballero Eduardo , Cintas J. , Herrera-García M. , Cuevas Francicso Gomez , Martos Juan Manuel Montes
Published: November 2012

Aluminium powder was milled under vacuum and/or ammonia atmospheres, in order to evaluate the effect of the order of the atmospheres on the amount of nitrides appearing in the powder after a subsequent heat treatment. All milling experiences were carried out at room temperature for 5 h. The XRD study of sintered powders showed that important amounts of AlN appeared after heating. The use of vacuum and ammonia flow allows controlling the percentage of N rich phases formed. Moreover, the capacity of incorporating nitrogen to the aluminium lattice is very influenced by the vacuum and ammonia flow atmospheres order during the milling process.
A Comparative Study of the Results Obtained through Different Types of Wear Tests
Authors: García Ana , Ferreiro Laura , Varela Angel , Mier José Luís , Camba Carolina , Barbadillo Fernando
Published: November 2012

Wear is one of the most worrying problems in industry; it affects many production sectors. Therefore, the wear resistance of materials must be assessed in order to predict their response and anticipate possible failures. Maintenance could then be scheduled accordingly. Due to the large number of situations where wear is important, one of the main complications in tribology is that it is difficult to replicate in a laboratory the precise conditions of service. Thus, there is a need to choose between different kinds of tests to simulate actual conditions. However, this aim is difficult to achieve, as variables and conditions of service are numerous. In this situation, it is neither practical nor possible to have as many test devices in the laboratory as real possibilities. It is necessary to find a test that can be extrapolated to many possible situations. An important question is if the results obtained with different configurations simulated in the laboratory are good equivalents or, on the contrary, the choice of method has an influence and to what extent the latter case is true. In addition, it should be noted that wear test standards mention how difficult it is to reproduce results and how they are influenced by operating conditions In this paper, three wear tests methods are studied- the pin-on-disk, dry sand/rubber wheel test and wet sand/rubber wheel- in order to find a relationship between the results obtained by them. Furthermore, different techniques are analysed to establish, if possible, which ones are more likely to achieve more reliable results.
A Study on Shrinkage and Warpage of Rotational Moulded Polyethylene
Authors: Costa Luis , Cramez Maria Clara , Pontes A.J.
Published: November 2012

Warpage and poor dimensional stability of rotomoulded products are two of the main obstacles to the use of this technique in the production of engineering parts. The knowledge of the effect of the processing conditions on the shrinkage of rotomoulded parts will allow overcoming some of the restrictions of this process. In the present work the influence of the processing conditions on the development of shrinkage and warpage of rotomoulded parts was studied. The moulding of the parts was performed using a rotational moulding machine build at the University of Minho. The shrinkage and the warpage of the moulded parts were assessed using 3D MMC (3D measuring Machine Control) equipment, and understanding the microstructural development.
Assessment of the Shrinkage and Ejection Forces of Reinforced Polypropylene Based on Nanoclays and Short Glass Fibre
Authors: Garcia Mauro C.R. , Netto Aurelio C.S. , Pontes A.J.
Published: November 2012

In this study the influence of nanoclay and glass fibre in the shrinkage and ejection forces in polypropylene matrix in tubular parts moulded by injection moulding were analysed. An instrumented mould was used to measure the part surface temperature and ejection forces in tubular parts. The materials used were a polypropylene homopolymer Domolen 1100L nanoclay for polyolefin nanocomposites P-802 Nanomax in percentages of 2%, 6% and 10% and a polypropylene homopolymer with content of 10% of glass fibre Domolen P1-013-V10-N and 30% of glass fibre Domolen P1-102-V30-N with 2% of nanoclay. The shrinkage and ejection forces were analysed. The results show that the incorporation of nanoclays decreases the shrinkage and ejection forces whereas glass fibre decreases the shrinkage and increase ejection forces due to the increase of the elastic modulus. The nanoclays decrease the ejection force when compared with glass fibre and pure PP. The effects of nanoclays are less pronounced than those of glass fibre. The effect of the mould temperatures on the ejection forces in the mouldings produced with the mentioned materials were also analysed. The ejection force decreases with the increase of the temperature of the mould.
Characterization of Polypropylene Structural Foams for Large Part Applications
Authors: Esteves Fantina R. , Pouzada António Sergio , Martins Carla I.
Published: November 2012

Structural foams (SF) consist of a sandwich-like material composed by a cellular core and a solid skin. It is the ideal material solution for injection moulding of short production series of large size parts. The injection moulding of SF is a low pressure process, thus it is a viable alternative for light moulding tools. The right formulation of structural foams and the use of adequate processing conditions are important to optimize the performance of the plastics part. In this study the processing conditions (injection speeds and percentages of mould filling) and the amount of chemical blowing agent (CBA) added to polypropylene were assessed on injection moulding circular discs. A hybrid mould with epoxy/aluminium composite cavity was used to produce the parts. The structural foam performance was evaluated by rheological, morphological and mechanical tests.
Glulam Mechanical Characterization
Authors: Sousa Hélder S. , Branco Jorge M. , Lourenço Paulo B.
Published: November 2012

The glued laminated timber (glulam) mechanical properties may be evaluated through the determination of the key mechanical properties of the lamellae that compose that element. Simple bending and tension parallel to the grain tests were performed in order to assess the strength class of three glulam elements. Regarding the bending tests, 8 samples were taken from a glulam beam and assessed. Values for the resistant bending tension and both local and global modulus of elasticity were obtained. For the tension parallel to the grain tests, a total of 120 samples were assessed. The samples were divided regarding the structural element from where they were extracted as well to the type of failure mode found in the tests. The values of the lamellae properties were then used for determination of the properties of the glulam material. The data gathered from the tests was assessed statistically and concluded that the mechanical properties of the glulam elements did not fulfill the required parameters of the normative requirements.
Predicting the Unpredictable: Forecastable Bubbles and Business Cycles under Rational Expectations
Authors: Gracia Eduard
Published: November 2012

A popular interpretation of the Rational Expectations/Efficient Markets hypothesis states that, if it holds, market valuations must follow a random walk; hence, the hypothesis is frequently criticized on the basis of empirical evidence against such a prediction. Yet this reasoning incurs what we could call the ‘fallacy of probability diffusion symmetry’: although market efficiency does indeed imply that the mean (i.e. ‘expected’) path must rule out any cyclical or otherwise arbitrage-enabling pattern, if the probability diffusion process is asymmetric the observed path will most closely resemble not the mean but the median, which is not subject to this condition. In this context, this paper develops an efficient markets model where the median path of Tobin’s q ratio displays regular, periodic cycles of bubbles and crashes reflecting an agency problem between investors and producers. The model is tested against U.S. market data, and its results suggest that such a regular cycle does indeed exist and is statistically significant. The aggregate production model in Gracia (Uncertainty and Capacity Constraints: Reconsidering the Aggregate Production Function, 2011) is then put forward to show how financial fluctuations can drive the business cycle by periodically impacting aggregate productivity and, as a consequence, GDP growth.
NEKI ASPEKTI SEIZMIČKOG RIZIKA GRAĐEVINSKOG PROSTORA TERMOELEKTRANE UGLJEVIK – 3
Authors: Nedeljković Slobodan , Đurić Neđo , Popović Miodrag
Published: November 2012

Izgradnja Termoelektrane Ugljevik 3, snage 2 x 300 MW, zahtijevala je detaljnije proučavanje terena, posebno sa aspekta njegove seizmičnosti. Na terenu je ranije konstatovan rasjed u dijelu gdje su planirani budući objekti termoelektrane. Prethodnim terenskim istražnim radovima potvrđeno je njegovo prisustvo, što je što je zahtijevalo detaljnije analiziranje seizmičnosti terena u dijelu prostiranja rasjeda i neposredne okoline. Za analizu zemljotresnog hazarda korištene su seizmološke karte i tumač karte, gdje su izdvojena ograničavajuća područja očekivanih maksimalnih intenziteta temljotresa po MSK-64 skali, za određeni period sa vjerovatnoćom 63%. Analiza je pokazala da prisutni rasjedi na lokaciji nemaju seizmo kapacitet da izazovu seizmotektonske deformacije terena na lokaciji objekata i njihovoj okolini.
RAZVIJANJE KORELACIJA IZMEĐU MEHANIČKIH OSOBINA TLA
Authors: Talić Zlatan
Published: November 2012

Moguće je uspostaviti određene korelacije između geotehničkih parametara tla dobijenih u laboratoriji i na terenu, kao i indeksnih parametara. Ovi parametri bili bi utvrđeni na osnovu rezultata israživanja i ispitivanja koji bi obuhvatili: 

• geološke, inženjerskogeološke i hidrogeološke radove 

• istražna bušenja 

• standardna dinamička penetriranja u bušotinama (SPT) 

• istražna sondiranja 

• kontinuirana dinamička penetriranja (DPH) i 

• geomehanička laboratorijska ispitivanja uzoraka tla i stijena 

Podaci i rezultati navedenih radova predstavaljali bi polazište za sagledavanje geotehničkih parametara i uvjeta izgradnje autoputa na predmetnoj dionici.
Computational models that predict response to HIV therapy can reduce virological failure and therapy costs in resource‐limited settings
Authors: Revell A , Wang D , Alvarez‐Uria G , Streinu‐Cercel A , Ene L , Wensing A , Hamers R , Morrow C , Wood R , Tempelman H , Dewolf F , Nelson M , Montaner J , Lane H , Larder B ,   RDI Study Group
Published: November 2012

The results of genotypic HIV drug‐resistance testing are, typically, 60–65% predictive of response to combination antiretroviral therapy (ART) and have proven valuable for guiding treatment changes. However, genotyping is not available in many resource‐limited settings (RLS). The purpose of this study was to develop computational models that can predict response to ART without a genotype and evaluate their potential as a treatment support tool in RLS. Random forest models were trained to predict the probability of response to ART (<400 copies HIV RNA/ml) using the following data from 14,891 cases of ART change following virological failure in well‐resourced countries: viral load and CD4 count prior to treatment change, treatment history, drugs in the new regimen, time to follow‐up and follow‐up viral load. The models were assessed during cross‐validation, with an independent set of 800 cases, with 231 cases from RLS in Southern Africa, 206 from India and 375 from Romania. The area under the ROC curve (AUC) was the main outcome measure of the accuracy of the model's predictions. The models were used to identify alternative regimens for those cases where the salvage regimen initiated in the clinic failed. Finally, annual therapy costs were used to determine the potential cost effectiveness of this strategy for the Indian cases. The models achieved an AUC of 0.74–0.81 during cross validation and 0.76–0.77 with the 800 test TCEs. They achieved an AUC of 0.59–0.65 with cases from Southern Africa, 0.64 for India and 0.73 for Romania. The models identified alternative, locally available drug regimens that were predicted to result in virological response for 97% of cases where the salvage regimen failed in Southern Africa, 98% of those in Romania and 100% in India. Cost‐neutral or cost‐saving regimens that were predicted to be effective were identified for 88% of the Indian salvage failures with a mean saving of $638 per year. We developed computational models that predict virological response to ART without a genotype with comparable accuracy to genotyping with rules‐based interpretation. The models were able to identify alternative regimens that were predicted to be effective for the great majority of cases where the new regimen prescribed in the clinic failed. The models were also able to identify cost‐saving alternatives for most cases of failure in India. These models are now freely available over the internet as part of the HIV Treatment Response Predictions System (HIV‐TRePS), which has the potential to help optimise antiretroviral therapy in countries with limited resources where genotyping is not generally available.
Mentoring Activities of Senior Nurses and Performance of Nurse Trainees
Authors: Olaer Danilo C.
Published: November 2012

Mentoring is an important aspect in any field of discipline. It fosters an environment for the novice to imbibe the real work setting. This study ascertained the mentoring activities of senior nurses and the performance of nurse trainees. It utilized descriptive–correlational research design using a researcher-made questionnaire. The study was conducted at St. Vincent General Hospital, Cebu City, Philippines. The research subjects were the senior nurses while the respondents were the nurse trainees who underwent a training program. The data were statistically treated using simple percentage, weighted mean and Pearson-r. Based on the findings of the study, the mentoring activities exhibited by the senior nurses include those that reflect their roles as standard prodder model and envisioned. The respondents’ performance was found to be satisfactory based on the records of Human Resource Department. There was a significant relationship between mentoring activities and performance. The researcher concluded that performance of nurse trainees was dependent on the mentoring activities of the senior nurses. Thus, the researcher recommended implementing a mentorship training course for the senior nurses and monitoring the performance of nurse trainees by requiring very satisfactory rating as the basis for hiring to deliver maximum level of quality patient care.   Keywords - Mentoring, Mentoring Activities, Mentorship, Senior Nurses, Performance, Nurse Trainees, Mentor-Mentee Relationship
Comparison of drug concentrations measured in roadside surveys and in seriously injured drivers in Belgium
Authors: Van der Linden Trudy , Isalberti Cristina , Silverans Peter , Legrand Sara‐Ann , Verstraete Alain G.
Published: November 2012

The objective of this paper is to compare concentrations of alcohol, illicit, and medicinal drugs in seriously injured drivers and drivers selected randomly at the roadside. Blood samples were analyzed for alcohol, 17 medicinal drugs and 8 illicit psychoactive substances and/or their metabolites by ultra performance liquid chromatography‐tandem mass spectrometry (UPLC‐MS/MS) and gas chromatography mass spectrometry (GC‐MS) in injured drivers admitted to the emergency departments of five hospitals in Belgium between January 2008 and May 2010 and in drivers randomly selected between January 2008 and September 2009. Three hundred and seventy‐seven seriously injured drivers and 2750 roadside respondents were selected. In the roadside survey, out of the 203 concentrations above DRUID (Driving Under the Influence of Drugs, Alcohol and Medicines) cut‐offs for medicinal drugs, 51% were in the therapeutic range, 46% infratherapeutic, and 2.5% supratherapeutic. In the seriously injured drivers, out of the 78 concentrations above DRUID cut‐offs for medicinal drugs, these percentages were respectively 63%, 33%, and 4%. Significant differences were found in the distribution of concentrations for opioids, benzodiazepines, and Z‐drugs. For the latter, while in the seriously injured drivers study most concentrations were therapeutic, in the roadside survey most were infratherapeutic. The opposite was observed for the opioids. Eight and 41% of the roadside respondents and injured drivers, respectively, had an alcohol concentration above 0.1 g/L, with higher concentrations found in the injured drivers. For illicit drugs, significant differences were found for amphetamine and cocaine, for which respectively lower and higher concentrations were observed in the blood samples taken in the roadside survey. Copyright © 2012 John Wiley & Sons, Ltd.
Relationship between chemokine receptor expression, chemokine levels and HIV‐1 replication in the lungs of persons exposed to Mycobacterium tuberculosis
Authors: Kalsdorf Barbara , Skolimowska Keira H. , Scriba Thomas J. , Dawson Rod , Dheda Keertan , Wood Kathryn , Hofmeister Jessica , Hanekom Willem A. , Lange Christoph , Wilkinson Robert J.
Published: November 2012

Increased susceptibility to tuberculosis following HIV‐1 seroconversion contributes significantly to the tuberculosis epidemic in sub‐Saharan Africa. Lung‐specific mechanisms underlying the interaction between HIV‐1 and Mycobacterium tuberculosis infection are incompletely understood. Here we address these questions by examining the effect of HIV‐1 and latent M. tuberculosis co‐infection on the expression of viral‐entry receptors and ligands in bronchoalveolar lavage (BAL) of HIV‐1‐infected and ‐uninfected patients with and without latent M. tuberculosis infection.

Irrespective of HIV‐1 status, T cells from BAL expressed higher levels of the beta‐chemokine receptor (CCR)5 than peripheral blood T cells, in particular the CD8+ T cells of HIV‐1‐infected persons showed elevated CCR5 expression. The concentrations of the CCR5 ligands RANTES and MIP‐1β were elevated in the BAL of HIV‐1‐infected persons compared with that in HIV‐1‐uninfected controls. CCR5 expression and RANTES concentration correlated strongly with HIV‐1 viral load in the BAL. In contrast, these alterations were not associated with M. tuberculosis sensitisation in vivo, nor did M. tuberculosis infection of BAL cells ex vivo change RANTES expression.

These data suggest ongoing HIV‐1 replication predominantly drives local pulmonary CCR5+ T‐cell activation in HIV/latent M. tuberculosis co‐infection.
Chalcogenidotellurates(IV) (TeS3)2– and (TeSe3)2– by Low‐Temperature Solvothermal Synthesis from Liquid Ammonia and Methylamine
Authors: Kysliak Oleksandr , Beck Johannes
Published: November 2012

The novel chalcogenidotellurates(IV) [Zn(NH3)6][Zn(NH3)4]2(TeS3)3 (1), [Zn(NH3)4](TeSe3) (2), [Mn(NH3)6](TeS3) (3), [Mn(NH3)6](TeSe3) (4) and [Mn(CH3NH2)6](TeSe3) (5) were obtained by solvothermal reactions from elemental zinc or manganese, tellurium and sulfur or selenium, respectively, in liquid ammonia or methylamine. The reactions were performed in thick‐walled glass ampoules at 50 °C and give 1, 2 and 3 in quantitative yield. The yields for 4 and 5 are lower. The crystal structures consist of tetrammine, hexammine and hexakis(methylamine) complexes of divalent Zn and Mn and of trigonal‐pyramidal (TeCh3)2– (Ch = S, Se) anions. Compounds 1 (P31m) and 2 [two polymorphic forms, Cmc21 (2a) and Pca21 (2b)] crystallise in a noncentrosymmetric manner in polar structures, while 3 (P21/c), 4 (Pbca) and 5 (P21/m) are centrosymmetric. As an unique feature, the structure of 1 contains two different types of Zn ammine complexes, tetrahedral [Zn(NH3)4]2+ and octahedral [Zn(NH3)6]2+. Compound 5 contains the rare hexacoordinate complex [Mn(CH3NH2)6]2+. Raman spectra of 1 and 2 show the two expected symmetric and asymmetric valence vibrations between 350–380 cm–1 for (TeS3)2– and 215–235 cm–1 for (TeSe3)2–.