bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermo-Mechanical Modelling of Jointing Process by Friction Stir Welding of Aluminium-Based Composite Materials
Authors: Pop-Calimanu Marius , Fleșer Traian
Published: May 2012

Jointing with rotary active element gains field through technological facilities offered nowadays. Own research have developed a model for studying the thermal fields and the plastic deformations of jointing composite materials Al/20%SiC combined by friction stir welding (FSW). In this article we will present the three-dimensional distribution of investigated fields, correlated with input parameters in the process. The process is performed with solid state components. The numerical results indicate that the maximum temperature in the FSW process increases with increasing speed of rotational tools. For high speed welding joint, should be increased, at the same time, the rotational speed to avoid welding defects.
Simulation of Thermal Field in Fe73Cr2Ga4P13Si5C3 Bulk Metallic Glasses
Authors: Radu Bogdan , Buzdugan Dragoş , Codrean Cosmin , Şerban Viorel Aurel
Published: May 2012

This paper presents some results for numerical simulation of the thermal field developed during rapid cooling of iron base alloy (Fe73Cr2Ga4P13Si5C3), to obtain bulk metallic glasses. Technology of rapid cooling gives the possibility to obtain bulk metallic alloys with an amorphous structure which can be used for industrial applications like magnetic shields. Validity of the numerical model of the cooling process was confirmed by the X-ray diffraction analysis. Once the model being validate, it can be used to optimize the rapid cooling process and casting mold geometry to be able to investigate the possibility to obtain larger amorphous bulk components.
Experimental Investigation and Numerical Modeling Fracture Processes under Mode II in Concrete Composites Containing Fly-Ash Additive at early Age
Authors: Golewski Grzegorz L. , Sadowski Tomasz
Published: May 2012

Mode II fracture analysis is especially important. This mode is vital in relation to concrete, due to its relatively low shearing strength and high sensitivity to such type of stress. Nowadays, the structural concretes containing an additives of fly-ash are quite commonly used in the construction industry. Initial cracks origin and development research was carried out using samples for three concrete mixtures: concrete without silica fly-ash (FA), concrete with 20% and concrete with 30% FA additive. 150x150x150 concrete cube with two initial cracks was used as a test sample. Experimental investigation under Mode II fracture was carried out in concrete composites at early age (after 3, 7, 14 and 21 days). X-FEM method enables observation of defect initiation and development, there is no need to input the original conditions. Calculations used peak principal stress criterion. Most calculations coincide with results of experimental research. There was a convergence of: cracks shapes, FQ critical force values, force - displacement graphs.
Numerical Modelling of Thermally Bonded Nonwovens: Continuous and Discontinuous Approaches
Authors: Demirci Emrah , Hou Xiao Nan , Acar Memiş , Pourdeyhimi Behnam , Silberschmidt Vadim V.
Published: May 2012

Nonwoven fabrics are web structures of randomly-oriented fibres, bonded by means of mechanical, thermal or chemical techniques. This paper focuses on nonwovens manufactured with polymer-based fibres and bonded thermally. During thermal bonding of such fibres, as a hot calender with an engraved pattern contacts the fibre web, bond spots are formed by melting of the polymer material. As a result of this bonding process, a pattern of bond points connected with randomly oriented polymer-based fibres form the nonwoven web. Due to their manufacturing-induced composite microstructure and random orientation of fibres, nonwovens demonstrate a complex mechanical behaviour. Two distinct modelling approaches were introduced to simulate the non-trivial mechanical response of thermally bonded nonwovens based on their planar density. The first modelling approach was developed to simulate the mechanical behaviour of high-density nonwovens, and the respective fabric was modelled with shell elements with thicknesses identical to those of the bond points and the fibre matrix having distinct anisotropic mechanical properties. Random orientation of individual fibres was introduced into the model in terms of the orientation distribution function in order to determine the material’s anisotropy. The second modelling approach was introduced to simulate low-density nonwovens, and it treated the nonwoven media as a structure composed of fibres acting as truss links between bond points.
Considerations on Outliers in Medical Sciences and Materials Characterization
Authors: Cucuruz Laurentiu Roland , Nicoară Mircea , Răduţă Aurel , Locovei Cosmin , Cucuruz Maria , Tatu Fabian
Published: May 2012

Experimental research in both medical sciences and material science rely in many situations on a reduced quantity of available data, due to limited number of patients or high costs of samples. Some statistical data manipulation methods are discussed regarding their applicability, information content, value and limits. A special attention is given to the extreme values eliminated by the GRUBBS test. The necessity of the elimination of the extreme values is demonstrated.
Topography Imaging of Material Surfaces Using Atomic Force Microscope
Authors: Florea Cristina , Berdich Karla , Dreucean Mircea
Published: May 2012

The atomic force microscope (AFM) is a mechanical imaging instrument that measures the three dimensional topography at nanoscale as well as physical properties of a surface with a sharpened tip. This paper proposes an AFM imaging process for obtaining quality images in order to describe surface topography of different materials. Good topography information is a premise in nanoindentetion and in determining mechanical properties of materials. Samples used were: copper, nickel, titanium, polyamide and trabecular bone.
Size Effect on Fracture Toughness of Rigid Polyurethane Foams
Authors: Linul Emanoil , Marşavina Liviu , Sadowski Tomasz , Kneć Marcin
Published: May 2012

This paper presents the size effect on fracture toughness of polyurethane foams (PUR 40), with nominal density 40 kg/m3, closed-cell rigid foams widely used for sandwich cores. Determination of the fracture toughness was carried out by three-point bending tests (TPB), on notched specimens, at room temperature (20±2°C). To determine the size effect in Mode I fracture toughness, specimens geometrically similar in two dimensions with length-to-width ratio 5:2 were selected. The specimens were subjected to a quasi-static loading with a speed of 2 mm/min, which was applied exactly on the notch direction. A strong size effect in the closed-cell PUR foam is experimentally demonstrated, by considering a smooth transition between strength of materials approach (with no size effect) and asymptotic case of linear elastic fracture mechanics.
About Thermostability of Fe-Ni-P Amorphous Alloys
Authors: Raduta Aurel , Nicoară Mircea , Locovei Cosmin
Published: May 2012

A research program has been completed in order to analyze structural changes during heating of amorphous alloys belonging to Fe-Ni-P system. Special attention has been given to thermodynamics and mechanism of crystallization, to determine some aspects of development for crystalline phases. Experimental material used to determine characteristics of crystallization consisted in long ribbons, 30 thick and 18 mm wide, fabricated by mean of “Planar Flow casting” as amorphous Fe42Ni38P16B4 alloy. Differential Thermal Analysis (DTA) and X-rays diffraction have been used to determine crystallization temperature of this alloy. Curves of differential thermal analysis for heating rates ranging between 1°C/minute and 20 °C/minute have been used to determine activation energy of crystallization.
Stress Evaluation by Neutron and Synchrotron Radiation
Authors: Lodini Alain , Benmarouane Abdelilah
Published: May 2012

In this paper we present two studies in order to evaluate the residual stresses in two materials. The first one, the residual stresses regenerated in shot peened aluminium plate by neutron diffraction on the strain imaging instrument SALSA at the Institut Laue Langevin, Grenoble, France, also the validation of a model of finite element analysis permitting to predict the final deformation. The second example of this work we use the cobalt-alloys coating deposited on stainless steel forging tools via Plasma Transfer Arc (PTA) process, the evaluation of the residual stresses and characterization of phases close to substrate/coating interface were done by Synchrotron X-ray diffraction.
Thermal Stability and Crystallization Kinetics of Ti40Zr10Cu34Pd14Sn2 Bulk Metallic Glass
Authors: Calin Mariana , Stoica Mihai , Zheng Na , Wang Xiao Rui , Scudino Sergio , Gebert Annett , Eckert Jürgen
Published: May 2012

In this work, the isochronal and isothermal activation energies for the primary crystallization process of Ti40Zr10Cu34Pd14Sn2 bulk metallic glass have been studied by differential scanning calorimetry and determined using the Kissinger approach and the Johnson-Mehl-Avrami analysis, respectively. The activation energy for crystallization evaluated by the Kissinger method is 253 kJ/mol. Similar activation energy for crystallization was obtained from the viscosity measurements. The values of the differential Avrami exponent are also determined from the isothermal data. Assuming diffusion-controlled growth, it is shown that thermal treatment of the samples in the supercooled liquid region considerably influences the behavior of the nucleation rate during the crystallization process.
The Influence of the Mechanical Vibrations upon 1.7035 – 41Cr4 Steel during Hardening Process
Authors: Luca Mihai Alexandru , Machedon Pisu Teodor , Gadea Florin Constantin
Published: May 2012

After a number of experiments it was noticed that mechanical vibrations affect the process of austenite on cooling conversion. The behavior of 41Cr4 steel was studied during the hardening process in mechanical vibrations action environment. At low power of sinusoidal signal excitation, respectively at low amplitudes of test samples oscillations, a hardness increase can be observed, as well as on surface and in depth. By exciting the test samples on different resonance frequencies, when the oscillations amplitude is higher, it is obvious that the hardness of cooling surface remains high while the depth hardness decreases. This presumes a growth of resistance to abrasion and improvement of product toughness. By modifying the influences of the excitation system, the frequency and the power of the mechanical excitation generator can be achieved, both on test samples and different products, superior results about toughness, resistance to abrasion and endurance strength.
Controlled Temperature Distribution and Heat Transfer Process in the Unidirectional Solidification of Aluminium Alloys
Authors: Ştefănescu Florin , Neagu Gigel , Mihai Alexandrina , Stan Iuliana
Published: May 2012

Abstract. The paper presents some theoretical and experimental data regarding the directional solidification, revealing the main factors (especially those which are related to the heat transfer process) which have influence on the crystals size and morphology. The crystalline structure of alloys is determined by three important factors: chemical composition, thermal conditions, and characteristics of germination and growth from liquid of solid nuclei. The solidification structure can be influenced by acting on the mould properties or directly on the cast material, both of these actions being based upon the change of temperature distribution in the alloy-mould system. Experimental data demonstrated the major influence of the thermal regime on the crystallization-solidification process, on the transcrystallization zone and they pointed out the limits to direct the crystals formation (size and shape) by changing the cooling regime.
Structure Characteristics of Ce-Inoculated, Low Sulphur Grey Cast Irons
Authors: Anton Irina , Riposan Iulian
Published: May 2012

The structural characteristics of electric melt, as-cast grey irons were studied in critical solidification conditions, such as very low sulphur content (< 0.025%) and a low (%Mn) x (%S) control parameter (< 0.015) with low Al residual (< 0.002%), without resulphurising or preconditioning. The efficiency of Ce-Ca-Al-FeSi alloy was tested at lower addition rates (0.15-0.25wt.%), as traditionally high inoculant addition rates have been employed in low sulphur grey cast irons. Ce bearing ferrosilicon with similar Ca and Al levels appears to be more efficient than a commercial Ba-Ca-Al-FeSi inoculant, especially at low addition rates (< 0.2wt.%) for the key structure parameters: fewer carbides and less undercooled graphite with small eutectic cells at a higher count.
Complex Characterization of a New Low Ni Maraging Steel with Enhance Service Stability
Authors: Branzei Mihai , Nedelcu Ion , Miculescu Marian
Published: May 2012

A new low Ni maraging steel, based on 18Ni (300) type has been developed. The optimized chemical composition (complex alloyed with Al-Si-Ti or Si-Zr-Nb) in accordance with optimum heat treatment was found (solution: 970 °C/1h/air and ageing: 550 °C/3h/air), in order to obtain maximum service temperature of over 600 0C and ensured the good combination of strength and toughness properties. The precipitates, such as Ni3(Mo, Ti), were well controlled in lath martensite (Rm=2090N/mm2 and Rp0,2=1930N/mm2)and the presence of Si, Zr and Nb enhance structure stability at high temperature (for example the ultimate tensile strength at 5500C is about 1440N/mm2). Therefore, this new type of maraging steel was the subject of a national patent: “Maraging steel for high temperature service and heat treatment technology” – PATENT No.120356/30.08.2010.
Researches on the Influence of Chemical Composition Regarding the Physical-Mechanical Characteristics of Steel for the Manufacture of Monobloc Wheels
Authors: Andronache Constantin , Socalici Ana Virginia , Vilceanu Lucia , Hepuţ T.
Published: May 2012

Mechanical characteristics required for the manufacture of steel wheels piece of property gives it a combination of toughness with wear and fatigue resistance, so that rail movement to take place safely. Quality steels, physical-mechanical characteristics that are influenced by chemical composition, practical content elements influence positive and negative. This paper presents the correlations obtained by industrial processing in Excel and Matlab programs between chemical composition and physical-mechanical characteristics of steel components for the manufacture of rolling stock.
Physical Properties of Magnetorheological Fluid Dampers
Authors: Liţă Marin , Buzdugan Dragoş
Published: May 2012

This paper presents the preparation of magnetorheological fluids (MRF) starting from iron powder in size of 4-6 µm, silicone oil and a few commercial additives. The structure and magnetic properties of iron powder are evaluated by X-rays diffractions and hysteresis curves. The MRFs were selected through gamma radiation transmission, upon the determination of the sedimentation rate in the gravitational field. The dispersion of MRFs particles is presented using the electron transmission microscopy. The magnetorheological behavior in dynamic conditions was tested in a device specially designed for that purpose
Researches Regarding Elaboration of Barium Hexaferrite from Microwave Heating
Authors: Ştefan Iulian , Savu Sorin Vasile , Ghermec Olimpia , Nicolicescu Claudiu , Trotea Mario
Published: May 2012

The paper presents the results of experimental researches on the formation of barium hexaferrite type M (BHFM) by microwave heating. The microwave heating process takes only a few minutes to obtain calcined barium ferrite powders. Micronic and nanometric powders of BaCO3 and α-Fe2O3 were used as raw materials. In order to obtain BHFM, the microwave heating process was used with following mixtures: stoichiometric homogeneous mixture of BaCO3 and α-Fe2O3 powders, mechanically alloyed mixtures of BaCO3 and α-Fe2O3 powders for 5 and 20 hours in wet medium using a high energy ball mill Pulverisette 4. Using high energy ball milling, the powder size was turned into nanoscale. After using the microwave heating process it was observed a significant reduction of temperature-time parameters to BHFM formation for mechanically alloyed mixtures compared to homogeneous mixture.
A Study on Trace Elements Concentration in Bone Particles by XRF Analysis
Authors: Miculescu Florin , Ciocan Lucian Toma , Miculescu Marian , Ernuteanu Adrian , Antoniac Iulian , Matei Ecaterina , Pencea Ion
Published: May 2012

High concentrations of metals in the natural environment associated with industrial activity and increased migration of metals may cause an increase in the concentration of metals in living organisms, especially in the bone tissue, which reflects their total concentration in the body. Physiological basis for this assessment is based on the fact that the skeleton serves as a major reservoir for ingested heavy metals integrating them into bone matrix during calcification and where they remain until the bone is remodeled or resorbed. Investigations on the bone can be focused on three structural levels: mezostructural, micro, and nanostructural. In this study, we used X-ray fluorescence (XRF) to measure the residual amount of heavy elements in bone particles, obtained by a widely used method. The bones used to perform the experiments were collected from local hospitals, following certain surgical coxofemural prosthesis operations (according to agreed procedures on patient privacy and medical ethics).Studies carried out on samples taken from humans have shown that the variability in bone chemical composition is depending on subject living area, which is essential for understanding the contribution of these factors on bone mass and constitution. Comparing values obtained with concentrations of metals in bones reported by other authors allowed us to conclude that EDPXRF method can be used to assess tissue concentrations of natural elements and the results provide a basis for evaluating metal loading of the human body.
Empirical Determination of the Diffusion Coefficient of Carbon in Austenite in Carburizing Phase of the Gas-Carburizing-Sintering Process
Authors: Trotea Mario , Mangra Mihail , Ghercioiu Jeni , Ştefan Iulian
Published: May 2012

Numerical simulation of a mass-diffusion analysis requires several parameters in order to comply with experimental method of gas – carburizing of iron powder compacts. Among the known parameters of mass-diffusion process, the diffusivity is an uncertain parameter in terms of its value. Different formulas can be found in literature but most of them are empirical determined since different results of carbon content are obtained by numerical mass-diffusion analysis. For iron powder compacts with rectangular shape subjected to gas – carburizing – sintering process it was determined the average carbon content in several layers. Based on these determinations and on the characteristics of mass diffusion analysis using Abaqus software it was empirically determined the diffusivity dependency on the carburizing time.
Researches Regarding the Properties of Sintered Electrical Contacts Obtained From Mechanically Alloyed W-Cu Powders
Authors: Predescu Constantin , Nicolicescu Claudiu , Gavrila Marin
Published: May 2012

In this paper are presented the experimental results regarding the elaboration of electrical contacts using W-Cu composite powders obtained by mechanical alloying (MA) process. For the research commercial powders with a particle size between [10-80] µm were used. Three types of mixtures with different concentrations as follow: 90W-10Cu; 80W-20Cu; 70W-30Cu were mechanically alloyed for 2 up to 6 hours using a planetary ball mill. The mixtures obtained after MA process were pressed in a cylindrical die at 400 respective 600 MPa. The evolution of green densities function the compaction pressure and Cu content was studied. The green billets were sintered in an electrical furnace at 1180 oC and maintained 60 minutes at the sintering temperature in argon atmosphere. The evolution of densities, microstructures and electrical properties of the sintered samples function the Cu content and compaction pressure were studied.
Influence of the Energy Density on the Porosity of Polyamide Parts in SLS Process
Authors: Toth-Taşcău Mirela , Raduta Aurel , Stoia Dan Ioan , Locovei Cosmin
Published: May 2012

This paper presents an experimental study about the influence of the Selective Laser Sintering process parameters on the surface and cross-section porosity of parts sintered in polyamide PA2200 material two times recycled. Using of recycled powder affects the part structure and mechanical properties. Therefore, the paper aims to develop a suitable strategy to improve the part structure by controlling the most important SLS process parameters. The main process parameter whose influence was studied is the energy density of the laser beam. Special sample was designed and prototyped using EOS P100 prototyping machine. Three repetition jobs with different energy density of the laser beam were performed. Scanning Electron Microscopy was used to analyze the surface morphology and microstructure of the sintered benchmark parts. The relationship between the SLS parameters and part quality will extend the use of PA2200 recycled material.
Thermal Stability of Ni40Ti40Nb20 and Ni32Ti48Nb20 Tapes Obtained by Rapid Solidification Technique
Authors: Thalmaier György , Vida-Simiti Ioan , Jumate N. , Şerban Viorel Aurel , Codrean C. , Nicoară Mircea , Bukkosi L.
Published: May 2012

Nickel–titanium- group 5A metal (V, Nb, Ta, Zr) alloys are known as promising hydrogen-selective membrane materials. They can potentially be used in membrane reactors, which can produce high-purity H2 and CO2 streams from coal-derived syngas at elevated temperatures. The master alloys were prepared by arc melting using high purity metals in a Ti-gettered argon atmosphere. The alloys were melted several times in order to improve homogeneity. The ingots were induction-melted under a high-purity argon atmosphere in a quartz tube and graphite crucible injected through a nozzle onto a Cu wheel to produce rapidly solidified amorphous ribbons. Thermal stability of the Ni40Ti40Nb20 and Ni32Ti48Nb20 thin tapes has been examined using DTA analysis.
Wear Resistance of Internal WC-CoCr Coatings Produced by High Velocity Oxy-Fuel Spraying
Authors: Secosan Ioan Florin , Uţu Ion Dragoş , Şerban Viorel Aurel , Brandl Waltraut
Published: May 2012

Thermal spray coatings, and in particular those applied by HVOF process, are being used in a diverse range of engineering applications to extend component life by retarding wear and corrosion degradation [1]. Coatings performance is strongly dependent on microstructure [2]. The mechanical properties are a complex function of carbide size, shape and distribution, matrix hardness and toughness and the presence of various reaction products. This paper is focused on the wear resistance of WC-based coatings containing 10 mass% Co and 4 mass% Cr as the metallic binder, involving a heat-treated steel rings as substrate, a hot rolled product of structural steel in accordance with DIN EN 10113-2 for steel construction, detaining a tensile strength about 520-680 N/mm2. A feedstock powder of WC-CoCr 86 10 4 agglomerated/sintered was used for coatings production. It has good properties, such as: high resistance against oxidation and corrosion (due to the metallic component), good wear resistance (due to the ceramic component) and with a hardness in range of 1000-1300HV. The coatings have been produced by HVOF spraying of four different WC-CoCr grain size of powder particles, such as:sample 1 (-45+22µm), sample2 (-22+5µm), sample 3 (-10+2µm) and sample 4 (-2+0.5µm), using an ID CoolFlow mono gun developed especially for internal surfaces. This type of gun is a HP HVOF system for high pressure, but cold internal HVOF spraying. The morphology and the structure of the sprayed coatings were investigated by means of scanning electron microscopy (SEM/EDS) and the qualitative and quantitative phase composition of those coatings were determined applying the x-ray diffraction technique (XRD). In order to determine the sliding wear resistance of the coated samples, it was used the pin on ring test method under dry condition, with and without compressed air. This method consists into a stationary ball loaded against a ring sample in relative motion. The sliding wear rate of the tested samples was calculated from the volume of material lost during the test. The investigated samples were examined by means of stereo and light microscopy before and after exposure to wear tests. Based on the obtained results it was demonstrated that the coatings obtained from -10+2µm powder particles exhibit an optimal wear behavior when exposed to severe conditions.
Comparison of Structure and Wear Properties of Fine-Structured WC-CoCr Coatings Deposited by HVOF and HVAF Spraying Processes
Authors: Hulka Iosif , Şerban Viorel Aurel , Niemi Kari , Vuoristo Petri , Wolf Johannes
Published: May 2012

The aim of the work was to study the microstructure and wear properties of fine-structured HVOF and HVAF sprayed WC-10Co-4Cr coatings prepared from powder having submicron-sized tungsten carbides. The coatings were deposited by HVOF (High Velocity Oxygen Fuel) and HVAF (High Velocity Air Fuel) using propane as a fuel gas in both processes, and using oxygen or air as oxidizing gas for combustion, respectively. Nitrogen was used as carrier gas for the powder. Commercially available agglomerated and sintered cermet powder with main carbide sizes under 500 nm was used in this study. Scanning electron microscopy (SEM) and X-ray diffraction were performed in order to characterize the powder and the microstructures formed during the spraying processes. The microhardness HV0.3 of the coatings was investigated and the pin on disk test was used to determine the sliding wear behaviour. The rubber wheel abrasion test was performed in order to determine the abrasion wear resistance of the coatings.
Structural Analysis of PM Biocomposites Based on Hydroxyapatite Nanopowders Elaborated by Spark Plasma Sintering Route
Authors: Olei Bebe Adrian , Gîngu Oana , Lupu Nicoleta , Sima Gabriela
Published: May 2012

The objective of this research is the development of a detailed structural analysis of biocomposites with ceramic matrix of hydroxyapatite (Hap) reinforced by titanium (Ti), elaborated by powder metallurgy technology. Nanometric Hap powders (<200nm) 75% wt and micrometric Ti powders (<150μm) are homogenized in a high energy ball mill Pulverisette 6. Spark plasma sintering (SPS) is the sintering route able to lead to nanostructured sintered samples when nanopowders are used as raw material. The SPS parameters are: the sintering temperature, T=(1000-1100)°C and the maintaining time, t=(10-20) minutes in vacuum. The influence of the sintering parameters on the composites structures is monitored using the optical microscopy (OM), electronic microscopy (SEM) and the X-Ray diffraction (XRD).
Comparative Study of the Biomechanics of Materials Used in Stenting
Authors: Enkelhardt Angelica , Nes Cristian Sorin , Faur Nicolae
Published: May 2012

This paper presents a comparative bibliographic study of different materials with elevated biomechanical biocompatibility regarding the stent-blood vessel interaction. Only the materials used in coronary stents’ manufacturing are considered: stainless-steel (316L), Cobalt-Chromium alloys (CoCrMo, CoNiCrMo), Nickel-Titanium alloys (Nitinol), Tantalum. The main characteristics that result from the stress-strain curve of each material are presented, as well as the biocompatibility and durability. The stainless-steel has good mechanical properties, excellent biocompatibility and low price. Cobalt-Chromium alloys have excellent mechanical properties, excellent biocompatibility, acceptable shape memory properties, but high density and low flexibility. The Nitinol represents the best choice, with excellent mechanical properties, excellent biocompatibility, good corrosion resistance, high flexibility (super-elastic behavior), low density, but high price. Tantalum alloys present the best biocompatibility and high flexibility, but the mechanical properties are relative modest.
THE TRAGEDY CAUSED BY FAKE ANTIMALARIAL DRUGS
Authors: Ambroise-Thomas Pierre
Published: May 2012

Counterfeit antimalarials (mainly artemisinin derivatives) is a crucial health problem in developing countries, particularly in Africa. The illegal production, sale and distribution of fake drugs is a huge market evaluated to several billion of dollars and represents more than 50% of the pharmaceutical market in several African countries. Fake drugs have led to a very great number of deaths from untreated malaria or fatality provoked by toxic ingredients. These fake medicines increase the risk of artemisinin resistance developed by the use of sub therapeutic dosages of antimalarials. Tackling this criminal traffic is the objective of an international  programme created by WHO  and involves the international police and custom organizations like INTERPOL. Several very important and encouraging results have been obtained, but the problem will be completely solved if genuine antimalarials, free-of-charge, are handed-over to populations in sub Sahara African countries.
MENDELIAN SUSCEPTIBILITY TO MYCOBACTERIAL DISEASE IN EGYPTIAN CHILDREN
Authors: Galal Nermeen , Boutros Jeannette , Marsafy Aisha , Kong Xiao-Fei , Feinberg Jacqueline , Casanova Jean-Laurent , Boisson-Dupuis Stéphanie , Bustamante Jacinta
Published: May 2012

Background: Tuberculosis remains a major health problem in developing countries especially with the emergence of multidrug resistant strains. Mendelian Susceptibility to Mycobacterial Disease (MSMD) is a rare disorder with impaired immunity against mycobacterial pathogens. Reported MSMD etiologies highlight the crucial role of the Interferon gamma /Interleukin 12 (IFN-g/ IL-12) axis and the phagocyte respiratory burst axis.Purpose: Screen patients with possible presentations for MSMD.Methods: Patients with disseminated BCG infection following vaccination, atypical mycobacterial infections or recurrent tuberculosis infections were recruited from the Primary Immune Deficiency Clinic at Cairo University Specialized Pediatric Hospital, Egypt and immune and genetic laboratory investigations were conducted at Human Genetic of Infectious Diseases laboratory in Necker Medical School, France from 2005-2009. IFN-g level in patient’s plasma as well as mutations in the eight previously identified MSMD-causing genes were explored.Results: Nine cases from eight (unrelated) kindreds were evaluated in detail. We detected a high level of IFN-g in plasma in one patient. Through Sanger sequencing, a homozygous mutation in the IFNGR1 gene at position 485 corresponding to an amino acid change from serine to phenylalanine (S485F), was detected in this patient.Conclusion: We report the first identified cases of MSMD among Egyptian patients, including in particular a new IFNGR1 mutation underlying IFN-gR1 deficiency. The eight remaining patients need to be explored further. These findings have implications regarding the compulsory Bacillus Calmette Guerin vaccination policy in Egypt, especially given the high consanguinity rate.Keywords: Interferon gamma axis, mycobacterium tuberculosis, BCG, consanguinity
Emergency Contraception Options: Focus on Ulipristal Acetate
Authors: Cameron Sharon T.
Published: May 2012

Ulipristal acetate (UPA) is a progesterone receptor modulator that is available for emergency contraception (EC) and can be taken up to 120 hours after unprotected intercourse. A meta-analysis of clinical trials comparing UPA with levonorgestrel (LNG) for EC, demonstrated that UPA has higher efficacy than LNG. This higher efficacy is supported by biomedical studies that have demonstrated that UPA is a more potent inhibitor of ovulation, being able to delay ovulation in the immediate preovulatory period, when LNG is no longer effective. A recent study that explored risk factors for failure of EC, demonstrated that obese women were at increased risk of EC failure, with either UPA or LNG. However, failure was significantly less amongst women receiving UPA than those receiving LNG. There is growing evidence therefore, that UPA should be the preferred oral method of EC.
Impact of the Partitioning Scheme on Divergence Times Inferred from Mammalian Genomic Data Sets
Authors: Voloch Carolina M. , Schrago Carlos G.
Published: May 2012

Data partitioning has long been regarded as an important parameter for phylogenetic inference. The division of heterogeneous multigene data sets into partitions with similar substitution patterns is known to increase the performance of probabilistic phylogenetic methods. However, the effect of the partitioning scheme on divergence time estimates has generally been ignored. To investigate the impact of data partitioning on the estimation of divergence times, we have constructed two genomic data sets. The first one with 15 nuclear genes comprising 50,928 bp were selected from the OrthoMam database; the second set was composed of complete mitochondrial genomes. We studied two partitioning schemes: concatenated supermatrices and partitioned gene analysis. We have also measured the impact of taxonomic sampling on the estimates. After drawing divergence time inferences using the uncorrelated relaxed clock in BEAST, we have compared the age estimates between the partitioning schemes. Our results show that, in general, both schemes resulted in similar chronological estimates, however the concatenated data sets were more efficient than the partitioned ones in attaining suitable effective sample sizes.
Um olhar sobre a origem da ciência da informação: indícios embrionários para sua caracterização identitária
Authors: Carvalho Silva Jonathas Luiz , Freire Gustavo Henrique de Araújo
Published: May 2012

Discute sobre fundamentos sociais, científicos e cotidianos que deram vazão para o advento da Ciência da Informação, visando conceber suas características identitárias. A condição problematológica do presente trabalho pode ser sintetizada a partir da seguinte pergunta: Quais os fatores diretos e/ou indiretos que deram vazão para o surgimento da Ciência da Informação? Quais as influências desses fatores para a construção e caracterização da identidade da Ciência da Informação? Tem como objetivo discutir sobre os diversos fenômenos sociais, acadêmicos e científicos que direta e/ou indiretamente promoveram origem a Ciência da Informação. Metodologicamente, o artigo apresenta uma pesquisa exploratória no contexto da investigação histórica por meio de uma revisão bibliográfica. Conclui que diversos fatores auxiliaram na origem e construção da Ciência da Informação mostrando a sua característica de ciência pós-moderna, sendo possível observar diversas características identitárias a partir dos elementos que deram vazão a origem da Ciência da Informação, tais como: identidade histórica (relação entre Biblioteconomia e Ciência da Informação); identidade de projeto (a Documentação de Otlet e La Fontaine); identidade partilhada (contribuição dos EUA e do continente europeu para criação da Ciência da Informação) e identidade institucional (criação de associações em Ciência da Informação).
Mejora de la interoperabilidad semántica para la reutilización de contenidos mediante sistemas de organización del conocimiento
Authors: Moreiro González José Antonio , Cuadrado Sonia Sánchez , Lara Jorge Morato
Published: May 2012

Los Sistemas de Organización del Conocimiento son recursos diseñados para mejorar la interoperabilidad, gestión y recuperación del conocimiento. Conforme se incrementan los recursos web se evidencia la falta de sistemas de organización del conocimiento, con el consiguiente impacto en la interoperabilidad de recursos. Los sistemas de organización del conocimiento son por definición herramientas complicadas y costosas, tanto en su creación como en su gestión. La reutilización de estructuras organizativas similares es un elemento necesario en este contexto. Se analizan experiencias de reutilización de sistemas de organización del conocimiento y se señala como los nuevos estándares están incidiendo en este aspecto.
Representações sociais sobre informação e conhecimento na educação a distância: um estudo de caso na UFMG
Authors: Araujo Sinay Santos Silva de , Moura Maria Aparecida
Published: May 2012

Este artigo apresenta os conceitos de informação e conhecimento adotados por alunos, professores e tutores oriundos dos cursos de graduação na modalidade de educação a distância em Ciências Biológicas e Matemática da Universidade Federal de Minas Gerais (UFMG). As representações sociais foram sistematizadas no estudo que investigou a formação da cultura informacional na modalidade de educação a distância. Foram utilizadas como referencial teórico a Teoria das Representações Sociais e a técnica do Discurso do Sujeito Coletivo (DSC), desenvolvida por Lefevre e Lefevre. De acordo com as representações sociais dos sujeitos da pesquisa, a informação é a base para a construção do conhecimento e é compreendida como um fenômeno humano que se relaciona à produção de sentido. O conhecimento sistemático é compreendido como a informação que pode ser socialmente transmitida.
O blog como ferramenta de comunicação entre a biblioteca e seus usuários: a experiência da biblioteca Lydio Bandeira de Mello, da Faculdade de direito da Universidade Federal de Minas Gerais
Authors: Santos Ester Laodiceia , Rocha Suely Margareth da
Published: May 2012

Apresenta o blog Bibliojurídica como uma ferramenta de comunicação entre a Biblioteca Lydio Bandeira de Mello da Faculdade de Direito da Universidade Federal de Minas Gerais e seus usuários. Conceitua Web 2.0 e descreve o histórico, as definições, a tipologia e as principais características dos blogs. Caracteriza e define informação jurídica e apresenta a instituição para qual o blog foi criado. Demonstra a importância e funções do blog na biblioteca como recurso dinâmico de disseminação de informação e espaço de interação com os usuários. Descreve os procedimentos metodológicos utilizados na construção do Bibliojurídica, tais como objetivos, conteúdo, links, recursos tecnológicos, software e divulgação. Os resultados da sua implantação foram bastante positivos, diante das estatísticas de acesso e dos comentários postados. Conclui-se que o blog atendeu aos objetivos propostos e está sendo utilizado como um recurso de divulgação de produtos e serviços da biblioteca, contribuindo para melhorar a comunicação entre a mesma e seus usuários.
Alaskan soil carbon stocks: spatial variability and dependence on environmental factors
Authors: Mishra U. , Riley W. J.
Published: May 2012

Abstract. The direction and magnitude of soil organic carbon (SOC) changes in response to climate change depend on the spatial and vertical distributions of SOC. We estimated spatially-resolved SOC stocks from surface to C horizon, distinguishing active-layer and permafrost-layer stocks, based on geospatial analysis of 472 soil profiles and spatially referenced environmental variables for Alaska. Total Alaska state-wide SOC stock was estimated to be 77 Pg, with 61% in the active-layer, 27% in permafrost, and 12% in non-permafrost soils. Prediction accuracy was highest for the active-layer as demonstrated by highest ratio of performance to deviation (1.5). Large spatial variability was predicted, with whole-profile, active-layer, and permafrost-layer stocks ranging from 1–296 kg C m−2, 2–166 kg m−2, and 0–232 kg m−2, respectively. Temperature and soil wetness were found to be primary controllers of whole-profile, active-layer, and permafrost-layer SOC stocks. Secondary controllers, in order of importance, were: land cover type, topographic attributes, and bedrock geology. The observed importance of soil wetness rather than precipitation on SOC stocks implies that the poor representation of high-latitude soil wetness in Earth System Models may lead to large uncertainty in predicted SOC stocks under future climate change scenarios. Under strict caveats described in the text and assuming temperature changes from the A1B Intergovernmental Panel on Climate Change emissions scenario, our geospatial model indicates that the equilibrium average 2100 Alaska active-layer depth could deepen by 11 cm, resulting in a thawing of 13 Pg C currently in permafrost. The equilibrium SOC loss associated with this warming would be highest under continuous permafrost (31%), followed by discontinuous (28%), isolated (24.3%), and sporadic (23.6%) permafrost areas. Our high resolution mapping of soil carbon stock reveals the potential vulnerability of high-latitude soil carbon and can be used as a basis for future studies of anthropogenic and climatic perturbations.
Using Polycyclic Aromatic Hydrocarbons (PAHs) as a chemical proxy to indicate Tsunami 2004 backwash in Khao Lak coastal area, Thailand
Authors: Tipmanee D. , Deelaman W. , Pongpiachan S. , Schwarzer K. , Sompongchaiyakul P.
Published: May 2012

Abstract. In this study, we attempted to use PAHs as a chemical proxy to trace the transport of land-derived materials caused by the tsunami backwash to better understand how it may have affected the distribution of sedimentary deposition throughout the seabed of Khao Lak coastal areas. By analyzing the compositions of sedimentary PAHs in combination with application of the multivariate descriptive statistical techniques, PAHs were proven to be a promising chemical proxy to indicate the tsunami backwash in the study area. Their spatial distribution could indicate that the tsunami backwash plays an important role in transporting anthropogenic PAHs to the nearby coastal area as far as approximately 25 km from the shoreline. In addition, the results from diagnostic PAH isomer ratios suggested that road paving asphalt, originated from heavy erosion by the tsunami wave in front of Pakarang Cape, was among the identified sources of PAHs. Principle Component Analysis (PCA) results provided 2 estimated land-derived sources of PAHs, which were the road dust and oil burning sources. These estimated signature sources clearly support our hypothesis that PAHs were transported from the potential sources on land and deposited into the near-shore seabed during tsunami backwash.
Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal
Authors: Paulo A. A. , Rosa R. D. , Pereira L. S.
Published: May 2012

Abstract. Distinction between drought and aridity is crucial to understand water scarcity processes. Drought indices are used for drought identification and drought severity characterisation. The Standardised Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI) are the most known drought indices. In this study, they are compared with the modified PDSI for Mediterranean conditions (MedPDSI) and the Standardised Precipitation Evapotranspiration Index (SPEI). MedPDSI results from the soil water balance of an olive crop, thus real evapotranspiration is considered, while SPEI uses potential (climatic) evapotranspiration. Similarly to the SPI, SPEI can be computed at various time scales. Aiming at understanding possible impacts of climate change, prior to compare the drought indices, a trend analysis relative to precipitation and temperature in 27 weather stations of Portugal was performed for the period 1941 to 2006. A trend for temperature increase was observed for some weather stations and trends for decreasing precipitation in March and increasing in October were also observed for some locations. Comparisons of the SPI and SPEI at 9- and 12-month time scales, the PDSI and MedPDSI were performed for the same stations and period. SPI and SPEI produce similar results for the same time scales concerning drought occurrence and severity. PDSI and MedPDSI correlate well between them and the same happened for SPI and SPEI. PDSI and MedPDSI identify more severe droughts than SPI or SPEI and identify drought occurrence earlier than these indices. This behaviour is likely to be related with the fact that a water balance is performed with PDSI and MedPDSI, which better approaches the supply-demand balance.
Spatial and temporal variability of precipitation and drought in Portugal
Authors: Martins D. S. , Raziei T. , Paulo A. A. , Pereira L. S.
Published: May 2012

Abstract. The spatial variability of precipitation and drought are investigated for Portugal using monthly precipitation from 74 stations and minimum and maximum temperature from 27 stations, covering the common period of 1941–2006. Seasonal precipitation and the corresponding percentages in the year, as well as the precipitation concentration index (PCI), was computed for all 74 stations and then used as an input matrix for an R-mode principal component analysis to identify the precipitation patterns. The standardized precipitation index at 3 and 12 month time scales were computed for all stations, whereas the Palmer Drought Severity Index (PDSI) and the modified PDSI for Mediterranean conditions (MedPDSI) were computed for the stations with temperature data. The spatial patterns of drought over Portugal were identified by applying the S-mode principal component analysis coupled with varimax rotation to the drought indices matrices. The result revealed two distinct sub-regions in the country relative to both precipitation regimes and drought variability. The analysis of time variability of the PC scores of all drought indices allowed verifying that there is no linear trend indicating drought aggravation or decrease. In addition, the analysis shows that results for SPI-3, SPI-12, PDSI and MedPDSI are coherent among them.
“The Hallensians are Pietists; aren't you a Hallensian?”: Mühlenberg's Conflict with the Moravians in America
Authors: Atwood Craig D.
Published: May 2012

The rivalry between two centers of German Pietism, Halle and Herrnhut, shaped the development of both the Lutheran Church and the Moravian Church in America. The conflict began in Germany, but Pennsylvania became a major battleground in the 1740s. After years of sometimes violent controversy, the Moravians and Lutherans eventually developed as separate denominations. The most famous episode was the encounter on December 30, 1742, between Zinzendorf and Henry Melchior Mühlenberg, but that was just the first skirmish. Mühlenberg continued to oppose the Moravians after Zinzendorf's departure for Europe. In Philadelphia, Lancaster, and Tulpehocken Mühlenberg fought publicly with the Moravians over who would supervise Lutheran ministry in America. Mühlenberg intervened in several Lutheran congregations that had pastors friendly to the Moravians and asserted his own authority over them. Both sides used law courts and the press to assert their claim to be considered true Lutherans and convince the public that the others were heterodox “Pietists.”
The 1775 Correspondence of John Wesley and Francis Okely
Authors: Yonan Jonathan
Published: May 2012

On August 14, 1775, Francis Okely of Northampton, England, wrote a letter to the General Synod of the Moravian Church. Though a Moravian minister, his letter sought permission to preach for John Wesley in Towcester. Within his letter, Okely gave background to his request, including a paraphrase of a letter he had written to Wesley between July 24 and 31, 1775. His letter also reproduced a verbatim copy of the reply he later received from Wesley, dated July 31. This correspondence, apparently only preserved within Okely's August 14 letter, has never been published. It offers important insights into some of the interdenominational efforts to promote evangelical unity and to re-ignite evangelical revival in England.