Conference Papers in Science The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. LIAC Meeting on Vascular Research 2013 Wed, 20 May 2015 07:01:13 +0000 Marilena Formato, Vincenzo La Carrubba, Antonio J. Lepedda, Philippe Charpiot, and José Carlos Rodriguez-Cabello Copyright © 2015 Marilena Formato et al. All rights reserved. Differential Effect of Hypoxia in Human and Mouse Vascular Smooth Muscle Cell Migration through LRP1-pPyk2-MMP-9 Axis Tue, 19 May 2015 11:34:27 +0000 LRP1-pPyk2 axis is essential for the upregulatory effect of hypoxia on MMP-9 activation and human VSMC (hVSMC) migration. Currently, there are not efficient models for the translational study of atherosclerosis. The morphological and physiological features of atherosclerosis are different between human and animal models, particularly in mouse models. Therefore, the aim of current investigation was to compare the effect of hypoxia on LRP1-Pyk2-MMP-9 axis in human and mouse vascular smooth muscle cells (mVSMC) and its consequences on VSMC migration. We demonstrated that hypoxic modulation of LRP1-pPyk2-MMP-9 axis is opposite between hVSMC and mVSMC. The modulation of LRP1/pPyk2 levels by hypoxia is positive in hVSMC but negative in mVSMC. We showed that the inverse effect of LRP1/pPyk2 axis is associated with a differential effect of hypoxia on MMP-9 expression and activation. Hypoxia-induced MMP-9 activation was concomitant with an increased hVSMC migratory capacity. Surprisingly, mVSMC migrate under hypoxic conditions despite the downregulatory effect of hypoxia on MMP-9 expression or activation. Our results highlight the crucial role of LRP1-pPyk2-MMP-9 axis in vascular cell migration. In addition, we propose that the extrapolation of results from animal models to humans is not suitable for this specific mechanism in hypoxia-related vascular conditions. E. Revuelta-López, J. Castellano, D. de Gonzalo-Calvo, L. Nasarre, L. Badimon, and V. Llorente-Cortés Copyright © 2015 E. Revuelta-López et al. All rights reserved. Local Angiotensin Pathways in Human Carotid Atheroma: Towards a Systems Biology Approach Mon, 18 May 2015 06:43:34 +0000 We will summarize the data we have obtained in human carotid artery concerning the organization of an extended local renin angiotensin aldosterone system and its variations at different stages of atheroma. In a system view, we propose a model where concomitant increase in angiotensin and glucocorticoid signaling is induced and amplified in VSMC while vascular smooth muscle cells transdifferentiate toward a lipid storing phenotype. Giampiero Bricca, Liliana Legedz, Ali Nehme, Hanène Ayari, Christian Paultre, Wassim Hodroj, Jacques-Yuan Li, Jacques Randon, Olivier Lohez, Nedra Dhaouadi, Marie Paule Gustin, and Catherine Cerutti Copyright © 2015 Giampiero Bricca et al. All rights reserved. European Symposium on Friction, Wear, and Wear Protection Sun, 10 May 2015 12:50:22 +0000 Martin Dienwiebel, Matthias Scherge, Michael Moseler, Alfons Fischer, Ken’ichi Hiratsuka, and Julien Fontaine Copyright © 2015 Martin Dienwiebel et al. All rights reserved. A New Compression-Torsion-Tribometer with Scalable Contact Pressure for Characterization of Tool Wear during Plastic Deformation Tue, 05 May 2015 14:06:13 +0000 A contact pressure which reaches up to ten times the yield stress of the workpiece material is characteristic for cold extrusion processes. Common tests for friction and wear are limited to rather low contact pressures. Thus, the aim of this paper is to present a new compression-torsion-tribometer which is able to scale the contact pressure to a multiple of the yield stress of the workpiece. In order to enable a contact pressure that greatly exceeds the yield stress of the workpiece material, the workpiece specimen is encapsulated laterally. As main parameters, contact pressure, glide length, and relative velocity can be adjusted independently, thus allowing for multiple load cycles. The resulting torque is measured continuously as an indicator for wear. Afterwards wear can be also quantified by examination of surfaces. Hence, the developed setup enables a comparison of tool surfaces and coatings and a characterization of wear behaviour under high contact pressure. Marco Teller, Simon Seuren, Markus Bambach, and Gerhard Hirt Copyright © 2015 Marco Teller et al. All rights reserved. Tribological Characteristics of the Magnesium Matrix-Glassy Carbon Particles Composite Manufactured by Different Casting Methods Tue, 05 May 2015 14:01:00 +0000 A particulate composite with a magnesium matrix (Mg3Al) and glassy carbon particles (GCp) obtained under industrial conditions from a gravity cast and pressure die cast suspension was examined. The influence of the casting procedure on the microstructure and mechanical properties was revealed. Sliding friction tests by the pin-on-disc method for different loads (2.3, 5, and 9.3 N) and speeds (0.06, 0.09, and 0.14 m/s) were performed. Regardless of the technology, the sliding friction coefficient’s value strongly depended on the load and speed. Its value was changing (0.35–0.13) and was usually higher for the pressure die cast material, yet the wear resistance of the composite processed in that way was considerably better compared with the gravity cast. The results of the worn surface observation by SEM with EDS showed an influence of the initial Mg3Al-GCp composite’s microstructure on the processes of its wear. Anita Olszówka-Myalska, Jerzy Myalski, and Bartosz Hekner Copyright © 2015 Anita Olszówka-Myalska et al. All rights reserved. A Study of Correlation between Crack Initiation during Dynamic Wear Process and Fatigue Crack Growth of Reinforced Rubber Materials Tue, 05 May 2015 12:13:05 +0000 The aim of this study is concentrated on the experimental investigation of crack initiation during dynamic wear process and its correlation with fatigue crack growth of reinforced rubber materials. The analyzed rubber compounds suitable for applications such as treads for truck tires were based on natural rubber (NR) and polybutadiene rubber (BR). The dynamic wear behavior has been studied using an own developed testing equipment based on gravimetric determination of mass loss of test specimen. Fatigue crack growth (FCG) analysis was performed under pulse loading in accordance with real dynamic loading conditions of rolling tires using the Tear Analyser (TA). We show the crack initiation process during dynamic wear with respect to different impact energies and correlate the liability of crack initiation with FCG data at given tearing energy as a function of the rubber compositions. We demonstrate the higher crack initiation resistance of rubber blends with increased content of BR, while a predominant influence of NR improves the resistance against crack propagation especially at higher strain levels due to strain induced crystallization. Eric Euchler, Ondrej Kratina, Radek Stoček, and Michael Gehde Copyright © 2015 Eric Euchler et al. All rights reserved. Effect of Dilution on Microstructure and Wear Resistance of a Fe-Based Hardfacing Alloy with a High Amount of Carbide-Forming Elements Tue, 05 May 2015 12:11:09 +0000 Hardfacing is a widely diffused technique adopted to increase service life of parts for heavy-duty applications. Even though hardfacing alloys feature optimized chemistry and microstructure for specific service conditions, dilution with substrate modifies the resulting properties along a significant fraction of the deposit thickness. In particular, C and B diffusion to the substrate alters hypereutectic alloys reducing the carbide-forming ability and modifying the solidification sequence. In the present paper, the effect of dilution on a hypereutectic Fe-C-B based alloy containing Cr and Mo was investigated. The effect of dilution on the reference alloy was studied by producing laboratory castings with an increased amount of Fe, up to 50 mass %. The obtained results were compared with the dilution of the hardfacing alloy cast on steel substrates. The microstructural evolution was analyzed by XRD (X-ray diffraction), differential scanning calorimetry (DSC), optical microscopy (OM), and scanning electron microscopy (SEM), whereas mechanical behaviour was evaluated by hardness measurements and wear resistance by pin-on-disc tests. L. Rovatti, J. N. Lemke, N. Lecis, O. Stejskal, and M. Vedani Copyright © 2015 L. Rovatti et al. All rights reserved. On the Role of Oxidation in Tribological Contacts under Environmental Conditions Tue, 05 May 2015 11:57:42 +0000 Oxidation processes in tribological steel contacts are investigated, which are treated in a dry sliding, linear reciprocating model tribometer, by EDX (energy dispersive X-ray spectroscopy), AES (Auger electron spectroscopy), and HREFTEM (high resolution energy filtered transmission electron microscopy). Typical for steel contacts under environmental conditions is the feature that the counterparts are separated by oxide layers, which influence the tribological properties. And vice versa the tribological load will influence and change the oxide layers. The interaction of this dynamically coupled system was resolved by focussing the postexperimental surface analysis to long time stable balance states. As special challenge for the analyst of the tribological experiment under environmental conditions a postexperimental grown oxide layer covers the tribological induced changes and has to be distinguished from the tribological induced changes. Thick oxide layers, formed during the tribological load, were observed, which start to grow in form of islands and at the end separate the metallic bulk materials of the counterparts completely and avoid direct metal-metal contact. Thicknesses up to some microns strength, exceeding native oxide layers by magnitudes, were reached. Ploughing under fresh surface oxide and compacting and embedding of fresh oxidized debris particles were identified as main mechanisms responsible for the growing of these thick oxide layers. Rolf Merz, Alexander Brodyanski, and Michael Kopnarski Copyright © 2015 Rolf Merz et al. All rights reserved. A Novel Test Method to Determine the Wear Resistance of Agricultural Cutting Tools with an Analyzing Method Based on an Ellipse-Fit Algorithm Tue, 05 May 2015 11:25:21 +0000 Cutting belongs to the essential techniques in many fields of application in agricultural engineering. Cutting tools in agriculture are exposed to a high amount of abrasive wear and impact stress. Increasing the wear resistance of cuttings tools has a high significance for the efficiency and profitability of agricultural machinery. Blunt and deformed blades decrease the energy efficiency and the cutting quality. Blade failures cause machine breakdowns and increase labor and material costs. To enable a consistent and systematic optimization of the blades, a suitable testing method is necessary. Conventional field tests do not provide comparable and repeatable results. Therefore, a test method developed at the FMDauto in cooperation with the Ennepetaler Schneid- und Mähtechnik (ESM) GmbH & Co. KG is presented. The test bench provides standardized and repeatable conditions with a similar wear pattern which is found during field operations. One of the remaining challenges is a clear wear characterization. Existing analyzing methods do not consider the energy efficiency and do not determine the edge holding property clearly. In this paper, a new analyzing method based on an ellipse-fit method is introduced to rate the geometrical shape of the cutting edge and examine the wear resistance of different blades. Andreas Jahr, Robert Bongartz, Hunn Sim, and Alex Pillmann Copyright © 2015 Andreas Jahr et al. All rights reserved. Investigation of the Wear Resistance Properties of Cr/CrN Multilayer Coatings against Sand Erosion Tue, 05 May 2015 11:16:03 +0000 The wear of metallic components used in gas and steam turbines due to erosive sand particles leads to a tremendous decrease in their lifetime. This wear can be reduced by the use of suitable erosion resistant coatings resulting in lower maintenance costs. In this context, multilayer Cr/CrN PVD coatings using an industrial coater were designed and applied on Inconel 718, a material which finds its application in gas turbines. A variation in the bimodal period has been induced in order to achieve an optimal coating architecture providing optimum properties needed for the erosion resistant coatings. The coating was deposited using a single Cr-target with an induction of N2 during the nitriding phase at a temperature of 480–500°C and the coating thickness of 24–26 μm was kept constant throughout. The erosion tests were conducted at angles of 30°, 60°, and 90°. The sand used for the test is an irregular shaped SiO2. The erosion tests were followed by a detailed microscopic examination of the eroded coating structure in combination with nanoindentation and scratch tests. Muhammad Naveed, Aleksei Obrosov, and Sabine Weiß Copyright © 2015 Muhammad Naveed et al. All rights reserved. Surface Analysis of Chain Joint Components after Tribological Load and Usage of Antiwear Additives Tue, 05 May 2015 11:11:34 +0000 Wear in chain joints leads to an increased clearance and thus an elongation of the entire chain which determines the lifetime of the chain. This particularly applies for chains that are used in timing chain drives. The aim of this study was to investigate especially the influences of lubricant additives and a contamination with carbon black on the tribological behavior of chain joint components and to correlate these influences to observable changes in topographical and chemical surface properties. A precisely defined contact and load situation is essential for generating a comparable series of samples for surface analyses. To meet this requirement, chain joint component samples from tests on a linear reciprocating model tribometer were used for the following analyses. But to connect the results to the realistic situation regarding the typical wear rates of the subjected chain types, suited experimental parameters were selected. Topographical, structural, and chemical characterization of the worn surface regions of the components were performed after the tribological loading. The results show the influence of the lubricant, the additive, and the contamination with carbon black especially on the chemical properties of the component surfaces. D. Sappok, R. Merz, B. Sauer, and M. Kopnarski Copyright © 2015 D. Sappok et al. All rights reserved. Experimental Analysis of Microstructured Steel Surfaces for Wet Tribological Applications in the Low Velocity Regime Tue, 05 May 2015 09:46:36 +0000 The surface topography plays an important role in the design of a function-optimised surface. Therefore, the influence of topography with microsized structures produced by laser surface texturing (LST) is experimentally examined under lubricated sliding conditions. The structured specimens were made of AISI 51200 (DIN 100Cr6) hardened to about 800 HV. Concerning the requirements of tribological testing without any debris caused by the preprocessing, the structuring was carried out using a picosecond laser system (Trumpf TruMicro) with 6 ps pulse duration. A laboratory pin-on-disc tribometer (Plint TE-92 HS) was used for the tests, which were run under wet conditions with counterbodies made of bronze and steel at a nominal contact pressure of up to 4 MPa and sliding speeds between 0.04 and 2.0 m/s. Furthermore, start-stop cycles with accelerating and decelerating shares were used to simulate an automotive start-stop system. In the tribological experiments, a significant reduction of the friction coefficient was observed compared to sliding pairs without microstructured pin surfaces. Whereas no measureable wear occurred on the steel pins and discs, the bronze discs showed a significant amount of wear and the microstructures on the pin surfaces mated against bronze discs were almost completely filled with wear debris. Mateusz Chlipala, Johannes Schneider, and Volker Schulze Copyright © 2015 Mateusz Chlipala et al. All rights reserved. Bragg Fibers for Absorption-Based Sensing Wed, 01 Apr 2015 06:33:00 +0000 Photonic band gap Bragg fibers can be employed for delivery of high powers in medicine, lighting and heating systems, electricity production, and the development of optical sensors of physical and chemical variables. In this paper, results of testing Bragg fibers with hollow cores for pH detection based on absorbance measurements on solutions filled in the cores. Bragg fibers with claddings of three pairs of high- and low-index layers and hollow cores of 70 µm in diameter were fabricated. Photonic band gap bands of the fibers were estimated theoretically. Aqueous solutions of methyl orange (MO) and hydrochloric acid and bromothymol blue (BTB) in Sörensen buffers were filled into the cores and spectra of MO and BTB were measured for different pH. Calibration curves typical for optical pH sensors were derived from the measured spectra with a reproducibility of about 10%. Vlastimil Matějec, Ivan Kasik, Ondrej Podrazky, and Ivo Barton Copyright © 2015 Vlastimil Matějec et al. All rights reserved. Optical pH Detection with U-Shaped Fiber-Optic Probes and Absorption Transducers Thu, 12 Mar 2015 09:41:53 +0000 In medicine knowledge of pH values can provide us with information not only about the patients’ status but also about physiological processes in the patient’s body. Measurements of pH in small-sample volumes and online pH monitoring in vivo can be employed to obtain such information. For such measurements we have developed and investigated U-shaped fiber-optic probes with immobilized pH indicators in this paper. U-shaped probes with a diameter of about 2 mm were prepared. Three different pH indicators, methyl red, methyl orange, and bromothymol blue, were immobilized in two types of matrices, namely, porous silica (PS) and ethylcellulose (EC), and applied on the U-shaped probes. Changes in spectra of transmitted power were measured and calibration curves were determined from these spectra. It has been found that a working pH range of prepared probes was from 3.1 to 7.6. The maximum sensitivity was about 0.1 1/pH unit. Effects of structural relaxations of detection layers and indicator leaching observed in experiments are discussed. Jakub Zajíc, Lenka Traplová, Vlastimil Matějec, Marie Pospíšilová, and Ivo Bartoň Copyright © 2015 Jakub Zajíc et al. All rights reserved. National Conference on Advances in Material Science for Energy Applications Mon, 22 Dec 2014 09:36:28 +0000 S. Anantha Ramakrishna, Ramesh Chandra, G. N. Tiwari, P. Mandal, and R. K. Shivpuri Copyright © 2014 S. Anantha Ramakrishna et al. All rights reserved. Supernumerary Teeth: Review of the Literature with Recent Updates Tue, 02 Sep 2014 09:31:03 +0000 A supernumerary tooth (ST) is defined as any tooth or odontogenic structure that is formed from tooth germ in excess of usual number for any given region of the dental arch. They may be single or multiple and unilateral or bilateral in distribution and can occur in any region of the dental arch. These may occur in primary and permanent dentition. Supernumerary teeth are more frequent in males. They are classified based on form, morphology, location, and occurrence. Several hypotheses have been proposed to explain the occurrence of ST. However, combination of environmental and genetic factors has been proposed. Supernumerary teeth cause a range of complications like crowding, displacement, dilacerations, cyst formation, and so forth. Early identification and appropriate treatment plan should minimize the potential complications caused by ST. Sreekanth Kumar Mallineni Copyright © 2014 Sreekanth Kumar Mallineni. All rights reserved. Molecular Determinants for the Self-Assembly of Elastin Peptides Thu, 21 Aug 2014 07:20:22 +0000 Elastin and elastin-related peptides have great potential in the biomaterial field, because of their peculiar mechanical properties and spontaneous self-assembling behavior. Depending on their sequences and under appropriate experimental conditions, they are able to self-assemble in different fiber morphologies, including amyloid-like fibers. In this work, we will review recent data on elastin peptides derived from exon 30-coded domain of human tropoelastin. This domain has been shown to be fundamental for the correct assembly of elastin. However, the N-terminal region forms amyloid-like fibers, while the C-terminal fragment forms elastin-like fibers. A rationale for the varied aggregation pattern has been sought in the molecular structure of the peptides. Minimal differences in the sequences, adopting alternative conformations, are shown to be responsible for the observed data. Brigida Bochicchio, Maria Rosaria Armenante, Maria Antonietta Crudele, and Antonietta Pepe Copyright © 2014 Brigida Bochicchio et al. All rights reserved. Study of Rheological Properties of Industrial Lubricants Wed, 14 May 2014 06:49:39 +0000 The most important rheological parameter for lubricants is viscosity as it also affects the tribological properties like friction between interacting surfaces and wear. This research intends to study the relationship between viscosity and temperature at different shear rates for multiple grades of three different categories of lubricants used for different applications viz. L1: MG20W50 (engine oil), L2: SAE20W50 (engine oil), L3: MC20W50 (mineral engine oil), L4: EP90 (gear oil), and L5: DXTIII (steering fluid). Constant high dynamic viscosity, shear stress, and low compressibility at different temperatures in multigrade as well as single grade industrial oil will help to maintain the surface film over the period of time and hence the reduction in wear. The dynamic viscosity of these chosen samples has been measured experimentally in temperature range of 20 to 50°C. The measurements have been extended to observe the dependence of shear rate, time, and temperature on the dynamic viscosity. All the samples are observed to behave like Newtonian fluids in the entire temperature range of study. Further, all samples seem to obey the Arrhenius relationship with temperature. Shear stress shows linear variation with shear rate exhibiting uniform viscosity which is substantiated by almost no variation in dynamic viscosity with shear rate for value above 5 per second. Ajay Vasishth, Piyush Kuchhal, and Gagan Anand Copyright © 2014 Ajay Vasishth et al. All rights reserved. The Inhibitory Effect of Resveratrol on Elastin Amyloidogenesis Tue, 13 May 2014 07:27:36 +0000 The role of polyphenols in the prevention of degenerative diseases is emerging in the last years. In this report, we will investigate in vitro the inhibitory effect of resveratrol on elastin amyloidogenesis. The effect of resveratrol on molecular structure was investigated by circular dichroism spectroscopy, while the inhibitory effect on self-assembly was evaluated by turbidimetry as a function of temperature and by atomic force microscopy. Antonietta Pepe, Florian Delaunay, Angelo Bracalello, and Brigida Bochicchio Copyright © 2014 Antonietta Pepe et al. All rights reserved. PLLA/Fibrin Tubular Scaffold: A New Way for Reliable Endothelial Cell Seeding Mon, 12 May 2014 09:26:28 +0000 In the present work a simple and quick technique for cell seeding into tubular-shaped scaffolds, which allows a homogeneous cell distribution, was tested. The poly-L-lactide (PLLA) scaffolds, prepared via diffusion induced phase separation (DIPS), were filled with fibrin gel in order to obtain a hybrid scaffold for Vascular Tissue Engineering applications. The formation of immobilized fibrin networks on the inner surface of the tubular scaffolds was observed using confocal microscopy and SEM. Morphological analysis of the so-obtained scaffold revealed that the fibrin gel is uniformly distributed on the internal surface of the scaffold, leading to an organized structure. Moreover a penetration of the gel into the porous wall of the scaffold was observed. The in vitro endothelial cell cultures carried out in the scaffolds highlighted a faster cell proliferation inside the hybrid scaffold with respect to simple PLLA scaffold. Results show that the fibrin/PLLA hybrid scaffold may be favourably used for Vascular Tissue Engineering applications. Salvatrice Rigogliuso, Francesco Carfì Pavia, Vincenzo La Carrubba, Valerio Brucato, and Giulio Ghersi Copyright © 2014 Salvatrice Rigogliuso et al. All rights reserved. Modeling Cardiac Congenital Diseases: From Mathematic Tools to Human Induced Pluripotent Stem Cells Mon, 12 May 2014 07:47:18 +0000 Cardiac congenital diseases are rare inherited disorders characterized by anatomical malformations and/or by electrophysiological abnormalities, both affecting the whole heart function. In order to clarify the underlying pathophysiological mechanisms, experimental modeling has been proposed through in silico, in vitro, and/or in vivo simulations. Bioinformatics, transgenesis, heterologous expression systems, mammalian models, and, recently, pluripotent stem cells have been advanced to effectively recapitulate several human congenital diseases (such as Brugada syndrome, CPVT, LQTs, and ARVC) and, potentially, provide new insights into their pathomechanisms for novel therapeutic perspectives. Laura Iop Copyright © 2014 Laura Iop. All rights reserved. Conformation and Physical Structure of Tropoelastin from Human Vascular Cells: Influence of Cells Lipid Loading Mon, 12 May 2014 07:46:19 +0000 Aggregated low density lipoproteins (agLDL) contribute to massive intracellular cholesteryl ester (CE) accumulation in human vascular smooth muscle cells (VSMC). Our aim was to determine the conformational and physical structure of agLDL and elastic material produced either by control human VSMC or by agLDL-loaded human VSMC (agLDL-VSMC). At the conformational level scanned by FTIR spectroscopy, a new undefined, probably non-H-bonded, structure for tropoelastin produced by agLDL-VSMC is revealed. By differential scanning calorimetry, a decrease of water affinity and a drop of the glass transition associated with aggregated tropoelastin (from 200°C to 159°C) in the supernatant from agLDL VSMC are evidenced. This second phenomenon is due to an interaction between agLDL and tropoelastin as detected by the weak specific FTIR absorption band of agLDL in supernatant from agLDL-loaded VSMC. Valerie Samouillan, Jany Dandurand, Laura Nasarre, Lina Badimon, Colette Lacabanne, and Vicenta Llorente-Cortés Copyright © 2014 Valerie Samouillan et al. All rights reserved. Hyaluronan Produced by Smooth Muscle Cells Plays a Critical Role in Neointima Formation Mon, 12 May 2014 07:38:39 +0000 Large body of evidence supports the idea that microenvironment plays a critical role in several pathologies including atherosclerosis and cancer. The amount of hyaluronan (HA) is involved in the microenvironment alterations and the concentration of this polymer reflects the progression of the diseases promoting neoangiogenesis, cell migration, and inflammation. The HA synthesis is regulated by several factors: UDP sugar precursors availability and the phosphorylation of synthetic enzyme HAS2 as well as specific drugs reducing the UDP precursors. The HAS2 phosphorylation is done by AMP kinase, a sensor of cell energy. When the cells have low energy, AMP kinase is activated and modifies covalently the regulatory enzymes, blocking all biosynthetic processes and activating the energy producing metabolism. It was recently reported that the hexosamine biosynthetic pathway (HBP) may increase the concentration of HA precursor UDP-N-acetylglucosamine (UDP-GlcNAc) leading to an increase of HA synthesis. We demonstrated that the increase of HA synthesis depends on the HAS2 post translational modification O-GlcNAcylation, which increases HA secretion modifying a residue different from the phosphorylation site of AMP kinase. In this report we highlighted the critical aspects of the post translational HAS2 regulation and its influence on HA synthesis. Davide Vigetti, Sara Deleonibus, Eugenia Karousou, Manuela Viola, Giancarlo De Luca, and Alberto Passi Copyright © 2014 Davide Vigetti et al. All rights reserved. Biocompatibility Issues of Next Generation Decellularized Bioprosthetic Devices Mon, 12 May 2014 07:09:59 +0000 With respect to the limited lifespan of glutaraldehyde-treated bioprostheses (BHVs) to date there is almost no alternative when heart valve replacement surgery is required and most advanced current research attempts to develop tissue engineered valve scaffolds to be implanted in vivo or after in vitro preconditioning and dynamic seeding with host cells. However the clinical outcomes of grafting detergent-based cell-depleted tissue engineered xenogeneic constructs are still controversial. Insufficient quantitative evaluations performed at preclinical level about the residual content of xenogeneic epitopes, detergents, and nucleic acid materials in such scaffolds have led to disappointing and disastrous results. The risk of these dramatic accidents reoccurring remains very high unless safety and reliable control tools aimed to reach their complete removal, in order to consider tissues biocompatible and suitable for clinical practice. Michele Spina, Filippo Naso, Irene Zancan, Laura Iop, Monica Dettin, and Gino Gerosa Copyright © 2014 Michele Spina et al. All rights reserved. Dielectric Properties of SnO2 Thin Film Using SPR Technique for Gas Sensing Applications Tue, 06 May 2014 10:18:54 +0000 Focus has been made on the determination of dielectric constant of thin dielectric layer (SnO2 thin film) using surface plasmon resonance (SPR) technique and exploiting it for the detection of NH3 gas. SnO2 thin film has been deposited by rf-sputtering technique on gold coated glass prism (BK-7) and its SPR response was measured in the Kretschmann configuration of attenuated total reflection using a p-polarised light beam at 633 nm wavelength. The SPR response of bilayer film was fitted with Fresnel’s equations in order to calculate the dielectric constant of SnO2 thin film. The air/SnO2/Au/prim system has been utilized for detecting varying concentration (500 ppm to 2000 ppm) of NH3 gas at room temperature using SPR technique. SPR curve shows significant shift in resonance angle from 44.8° to 56.7° on exposure of fixed concentration of NH3 gas (500 ppm to 2000 ppm) with very fast response and recovery speeds. Ayushi Paliwal, Anjali Sharma, Monika Tomar, and Vinay Gupta Copyright © 2014 Ayushi Paliwal et al. All rights reserved. Study of Structural and Electronic Behavior of BeH2 as Hydrogen Storage Compound: An Ab Initio Approach Sun, 27 Apr 2014 09:13:31 +0000 The quantum mechanical calculations based on density functional theory (DFT) have been performed to study ground state structural and electronic properties of BeH2 and along with doping of two (BeH2 + 2H) and four (BeH2 + 4H) hydrogen atoms. The generalized gradient approximation (GGA) has been employed for the exchange correlation energy. The most stable space group of BeH2 is Ibam. Its optimized equilibrium unit cell volume, bulk modulus and its first-order pressure derivative, and electronic properties have been obtained. Our predicted unit cell parameters for BeH2   Å,  Å, and  Å are in very good agreement with the earlier reported experimental and theoretical results. The electronic band structure of BeH2 shows its behavior as an insulator. The stability of BeH2 along with doped hydrogen atoms increases, while the energy band gap decreases with the increase in number of doped hydrogen atoms. On these bases, we predict that BeH2 is a promising material for hydrogen storage. Vikas Nayak, Suman Banger, and U. P. Verma Copyright © 2014 Vikas Nayak et al. All rights reserved. WHO Ear and Hearing Disorders Survey: Ecuador National Study 2008-2009 Sun, 27 Apr 2014 07:55:13 +0000 Objectives. (1) Provide regional governments, institutions, and professionals with local and accurate information on the prevalence of ear and hearing disorders in the Ecuadorian population. (2) Contribute to the global burden of disease by generating standardized data that can be compared among countries and regions. Method. This was a prospective multistage cluster sample design study. Population tested included all members of households selected according to the sample strategy (cluster sample design). Testing was carried out in hospital facilities across the country including audiometry/TEAOEs and otological examination. Results. 5762 subjects were tested, with a global prevalence of hearing disability of 5% with a 95% CI of 3.9% a 6.1%. Out of the total population tested 14.52% are in need of action or services. Conclusions. The prevalence of disablility in hearing correlates with the prevalence found in other studies using the same protocol. The Ecuadorian population is in need of a substantial improvement in hearing services delivery. Alejandra Ullauri, Andrew Smith, Mauricio Espinel, Carlos Jimenez, Cesar Salazar, and Rodrigo Castrillon Copyright © 2014 Alejandra Ullauri et al. All rights reserved. Near-Field Hot Spots in Gold Nanoplasmonic Templates and Their Use for Surface Enhanced Raman Scattering Sensing Application Mon, 14 Apr 2014 06:13:14 +0000 Finite difference time domain (FDTD) method is adapted to investigate near-field enhancement effects on plasmonic structures (patterned in gold film) such as concentric rings with small separation, square, and rectangle. The near-fields effect on surface enhanced Raman scattering (SERS) is typically studied on square and rectangular structures. These metal structures are fabricated by laser interference lithography. Raman active molecules (Rhodamine 6G in PMMA (polymethyl methacrylate)) are spread onto patterned structure by spin coating, and Renishaw inVia Raman spectrometer was used to study SERS. Typical SERS enhancement of the order of 105 is seen for square and rectangular structures. It is observed that the corner points and edges of square and rectangular structures are most sensitive to concentrate near fields. In the case of concentric rings, huge near fields are seen to exist at the gap between the metal rings. Concentric rings are proposed to be very effective structure for SERS sensing applications such as molecular identification and biological mapping. Prasanta Mandal Copyright © 2014 Prasanta Mandal. All rights reserved. NO2 Sensing Properties of WO3 Thin Films Deposited by Rf-Magnetron Sputtering Thu, 10 Apr 2014 08:10:33 +0000 Tungsten trioxide (WO3) thin films were deposited by Rf-magnetron sputtering onto Pt interdigital electrodes fabricated on corning glass substrates. NO2 gas sensing properties of the prepared WO3 thin films were investigated by incorporation of catalysts (Sn, Zn, and Pt) in the form of nanoclusters. The structural and optical properties of the deposited WO3 thin films have been studied by X-ray diffraction (XRD) and UV-Visible spectroscopy, respectively. The gas sensing characteristics of all the prepared sensor structures were studied towards 5 ppm of NO2 gas. The maximum sensing response of about 238 was observed for WO3 film having Sn catalyst at a comparatively lower operating temperature of 200°C. The possible sensing mechanism has been highlighted to support the obtained results. Savita Sharma, Monika Tomar, Nitin K. Puri, and Vinay Gupta Copyright © 2014 Savita Sharma et al. All rights reserved.