Conference Papers in Science The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . 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. Harnessing Solar Energy for Every Home: Energy Saving Applications Thu, 10 Apr 2014 00:00:00 +0000 Most of the present day resources of energy are limited and irreplaceable. The next generation will face acute energy crisis if alternate resources of energy are not developed concurrently. Increasing cost and import of conventional resources have bad effect on the economy of a country, and the only cheaper solution is “unlimited power” from the sun. The use of solar energy is so far limited in household applications. In fact, if we harness only 0.0034 percent of the solar energy reaching the Earth’s surface, the energy need of the whole world will be met. In the present work, a substitute of 10-watt conventional night lamp has been proposed by a solar night lamp of the same light intensity through an experimental setup. The developed solar system is cheaper, portable, user friendly, and free from maintenance. The paper stresses on the need of replacement of conventional night lamp by solar night lamp in every home for reducing the energy crisis at present. Jitisha Aggarwal and M. L. Aggarwal Copyright © 2014 Jitisha Aggarwal and M. L. Aggarwal. All rights reserved. Study of Magnetic Property of Sn Doped Ni-Zn-Fe Nanoparticles Wed, 09 Apr 2014 13:26:38 +0000 The ( to ) samples were prepared by solution route technique. These samples were characterized by XRD and EPR spectra at X-band frequency (~9.2 GHz). The XRD spectra of these ferrites confirm the formation of spinel structure. The average particle size calculated by using Scherrer’s formula was found to be of the order of 24.7 nm. The EPR spectra of these ferrites are mainly due to Fe3+ ions. Fe2+ ions have very short spin-lattice relaxation time and therefore EPR spectra of Fe2+ could be observed only at very low temperature. This fact is also supported by the isomer shift values of these ferrites obtained from Mössbauer spectroscopy. The variation of and with Sn4+ concentration is attributed to the variation of superexchange interaction. Moreover in this system the dominant process of relaxation is the spin lattice relaxation rather than the spin-spin interaction. B. S. Tewari, Archana Dhyani, S. K. Joshi, Santosh Dubey, and Kailash Pandey Copyright © 2014 B. S. Tewari et al. All rights reserved. Oxidation State of a Polyurethane Membrane after Plasma Etching Tue, 08 Apr 2014 08:19:56 +0000 Low moduli cell culture substrates can be used to apply dynamic mechanical strain to cells, by surface deformation. Understanding the surface interaction with cells is critical to improving cell adhesion and normal growth. A medical grade polyurethane (PU), Chronoflex AL 80A, was modified by oxygen plasma etching and characterised by X-ray photoelectron spectroscopy. Etching resulted in increased cross-linking at the isocyanate bond and formation of new oxygen moieties. The model, derived from patent data and XPS data of the unetched PU, indicated that the additional oxygen was likely to be hydroxyl and carbonyl groups. Etched membranes enhanced protein adhesion, resulting in full surface coverage compared to unetched PU. The etched PU supported cell adhesion and spreading, while the unetched PU was not conducive to monolayer formation. Matthew D. Moles, Colin A. Scotchford, and Alastair Campbell Ritchie Copyright © 2014 Matthew D. Moles et al. All rights reserved. Antibacterial Activity of a Chitosan-PVA-Ag+-Tobermorite Composite for Periodontal Repair Mon, 07 Apr 2014 11:21:08 +0000 A polymer-mineral composite was prepared by solvent casting a mixture of chitosan, poly(vinyl alcohol), and Ag+-exchanged tobermorite in dilute acetic acid and characterised by scanning electron microscopy and Fourier transform infrared spectroscopy. The in vitro bioactivity of the CPTAg membrane was confirmed by the formation of hydroxyapatite on its surface in simulated body fluid. The alkaline dissolution products of the tobermorite lattice buffered the acidic breakdown products of the chitosan polymer and the presence of silver ions resulted in marked antimicrobial action against S. aureus, P. aeruginosa, and E. coli. The in vitro cytocompatibility of the CPTAg membrane was confirmed using MG63 osteosarcoma cells. The findings of this preliminary study have indicated that chitosan-poly(vinyl alcohol)-Ag+-tobermorite composites may be suitable materials for guided tissue regeneration applications. Andrew P. Hurt, Alejandra A. Ruiz de Clavijo, George J. Vine, Aimee A. Coleman, and Nichola J. Coleman Copyright © 2014 Andrew P. Hurt et al. All rights reserved. Dynamic Assessment of Fibrinogen Adsorption and Secondary Structure Perturbation Mon, 07 Apr 2014 00:00:00 +0000 Fibrinogen is a protein being of prime importance for the initiation of clotting and thrombus formation, readily adsorbed onto surfaces presenting both hydrophilic and hydrophobic nature. The mechanism of adsorption, and thus the final presentation of this protein are therefore important for subsequent involvement for, for example, platelet adhesion. Biological activity can be controlled through careful consideration of material design; here we report kinetic assessment of fibrinogen adsorption onto plasma polymerised allylamine (hydrophilic) and hexane (hydrophobic) surfaces, using FTIR-ATR to inform on kinetics of adsorption, secondary structure evaluation, and orientational variation. Fibrinogen was found to respond differently to these two surfaces, adsorbing more rapidly to hydrophilic surfaces and losing an ordered secondary structure over a much longer timescale compared to hydrophobic surfaces. Gaurang Khot, Folashade Kuforiji, Rupert Wright, and Paul Roach Copyright © 2014 Gaurang Khot et al. All rights reserved. On the Issue of Radiation-Induced Instability in Binary Solid Solutions Thu, 03 Apr 2014 16:06:14 +0000 The stability of a binary solid solution under irradiation has been studied. This has been done by performing linear stability analysis of a set of nonlinear reaction-diffusion equations under uniform irradiation. Owing to the complexity of the resulting system of eigenvalue equations, a numerical solution has been attempted to calculate the dispersion relations. The set of reaction-diffusion equations represent the coupled dynamics of vacancies, dumbbell-type interstitials, and lattice atoms. For a miscible system (Cu-Au) under uniform irradiation, the initiation and growth of the instability have been studied as a function of various control parameters. Santosh Dubey, S. K. Joshi, and B. S. Tewari Copyright © 2014 Santosh Dubey et al. All rights reserved. Effect of MgO and V2O5 Catalyst on the Sensing Behaviour of Tin Oxide Thin Film for SO2 Gas Wed, 02 Apr 2014 12:50:11 +0000 The present work shows the SO2 gas sensing property of SnO2 thin film based sensor prepared by using RF sputtering technique. Different catalysts (MgO and V2O5) in form of nanoclusters having diameter of 600 μm have been loaded on SnO2 surface to detect SO2 gas. The sensing response of all these films towards SO2 is monitored. Microstructural studies have been carried out using XRD and UV-Visible Spectrophotometer and a good correlation has been found between the microstructural and gas sensing properties of these deposited samples. Both catalysts when incorporated with SnO2 film show high selectivity towards SO2 gas at lower operating temperature. MgO gives a sensitivity of 317% at an operating temperature of 280°C towards 500 ppm of SO2 gas whereas V2O5 catalyst gives a sensitivity of 166% at 280°C for the same amount of gas. Punit Tyagi, Anjali Sharma, Monika Tomar, and Vinay Gupta Copyright © 2014 Punit Tyagi et al. All rights reserved. Synthesis and Characterisation of Thin Films of Bismuth Triiodide for Semiconductor Radiation Detectors Wed, 02 Apr 2014 09:12:34 +0000 Bismuth iodide is a potentially active material for room temperature radiation detector, as it is well reported in the literature that it has both wide energy band gap and high atomic absorption coefficient. Crystalline films of high atomic number and high radiation absorption coefficient can absorb the X-rays and convert them directly into electrical charges which can be read by imaging devices. Therefore, it was proposed to grow thin films of Bismuth iodide on glass substrate using thermal evaporation technique in vacuum to avoid the inclusion of impurities in the films. The structural studies of the films were carried out using XRD and optical absorption measurement was carried out in the UV/VIS region using spectrophotometer. All Bismuth iodide films grown at room temperature are polycrystalline and show X-ray diffraction peaks at angles reported in research papers. The optical transmission spectra of BiI3 films show a high transmission of about 80% in visible region with a sharp fall near the fundamental absorption at 650 nm. Resistivity of the as-grown film was found to be around 1012 ohm-cm suitable value for X-ray detection application. Films were subjected to scanning electron microscopy to study the growth features of both as-grown and annealed films. Alka Garg, Monika Tomar, and Vinay Gupta Copyright © 2014 Alka Garg et al. All rights reserved. Using Feed Forward Neural Network to Solve Eigenvalue Problems Mon, 31 Mar 2014 14:13:14 +0000 The aim of this paper is to presents a parallel processor technique for solving eigenvalue problem for ordinary differential equations using artificial neural networks. The proposed network is trained by back propagation with different training algorithms quasi-Newton, Levenberg-Marquardt, and Bayesian Regulation. The next objective of this paper was to compare the performance of aforementioned algorithms with regard to predicting ability. Luma N. M. Tawfiq and Othman M. Salih Copyright © 2014 Luma N. M. Tawfiq and Othman M. Salih. All rights reserved. Travelling along the Clinical Roadmap: Developing Electrospun Scaffolds for Tendon Repair Sun, 23 Mar 2014 08:03:02 +0000 Biopolymers, such as poly(ε-caprolactone), can be easily electrospun to create fibrous scaffolds. It is also possible to control the alignment of the emitted fibres and further manipulate these scaffolds to create 3D yarn structures, which resemble part of the tendon tissue hierarchy. Material properties, such as tensile strength, can be tailored depending on the selection and combination of polymer and solvent used during electrospinning. The scaffolds have been proven to separately support the adhesion and proliferation of equine tendon fibroblasts and human mesenchymal stem cells whilst simultaneously directing cell orientation, which caused their alignment parallel to the underlying fibres. Implantation of scaffolds into the flexor digitorum profundus tendon of mice hindpaws yielded encouraging results with minimal inflammatory reaction and observation of cell infiltration into the scaffold. This research demonstrates the progression of electrospun fibres along the clinical roadmap towards becoming a future medical device for the treatment of tendon injuries. Lucy A. Bosworth Copyright © 2014 Lucy A. Bosworth. All rights reserved. Poly(vinyl alcohol): Physical Approaches to Designing Biomaterials for Biomedical Applications Thu, 20 Mar 2014 17:50:20 +0000 Poly(vinyl alcohol) is a non-toxic, biosynthetic polymer and biocompatible polymer that has the ability to form hydrogels either via chemical or physical crosslinking. Whilst chemical crosslinking provides greater control on the properties of the resultant hydrogel, physically crosslinked hydrogels or blends with other biocompatible polymers are more suited for biomedical applications. In this paper we report a systematic study on the effect of varying concentrations of PVA, physical methods of crosslinking, and PVA-gelatin and PVA-PVP blends on the physical and mechanical properties of the hydrogels. Shathani Nkhwa, Kristo Fernando Lauriaga, Evren Kemal, and Sanjukta Deb Copyright © 2014 Shathani Nkhwa et al. All rights reserved. The Effect of UDMA/TEGDMA Mixtures and Bioglass Incorporation on the Mechanical and Physical Properties of Resin and Resin-Based Composite Materials Wed, 12 Mar 2014 10:39:47 +0000 Incorporating Bioglass into dental composites may improve biocompatibility and aid tooth and bone tissue remineralisation. This study aimed to determine the impact of Bioglass and silica filler on the mechanical and physical properties of cured photopolymers. Hardness (Vickers microhardness test), flexural strength (FS), and flexural modulus (FM) (three-point bend test) of resins containing various urethane dimethacrylate (UDMA)/triethylene glycol dimethacrylate (TEGDMA) and bisphenol A-glycidyl methacrylate (bisGMA)/TEGDMA concentrations (20–80 mass%) were tested. Degree of conversion (DC), FS, and FM of resin composites containing nonsilanised irregular 45S5-Bioglass (50 μm; 5–40 mass%) and/or silanised silicate glass filler particulates (0.7 μm; 30–70 mass%) were tested. Data was analysed using one-way ANOVA. UDMA/TEGDMA resins exhibited increased hardness and FM compared with bisGMA/TEGDMA resins. Addition of Bioglass particles to 60/40 wt% UDMA/TEGDMA or bisGMA/TEGDMA resins may enable the development of new materials that exhibit higher or at least equivalent values of DC, FS, and FM compared with conventional resin composites. Laura C. Nicolae, Richard M. Shelton, Paul R. Cooper, Richard A. Martin, and William M. Palin Copyright © 2014 Laura C. Nicolae et al. All rights reserved. Use of Poly (-Lysine) Dendrons: A Strategy Targeting Bacterial Quorum Sensing and Biofilm Formation Tue, 11 Mar 2014 12:51:53 +0000 Pseudomonas aeruginosa is recognised as a major aetiological agent of nosocomial infections, which are associated with multiple-antibiotic resistance. Among many of its important virulence factors is its ability to form biofilms on the surfaces of implantable medical devices and to produce toxic metabolites, pyocyanin, via an intercellular cell density-dependent signalling system of communication. In this study, poly (-lysine) dendrons composed of increasingly branching generations were synthesised, characterised, and examined for their effects on virulence factor production in P. aeruginosa. The results show that these hyperbranched poly (-lysine) dendrons, in particular the 3rd generation, can increase the efficacy of a conventional antibiotic, ciprofloxacin, and reduce pyocyanin production, with marginal effects on the rate of bacterial replication, suggesting that the observed effects are not due to dendron toxicity. Furthermore, dendron and ciprofloxacin coadministration was identified as the most effective strategy which highlights the potential of peptide-based dendrons as quorum sensing inhibitors. Rahaf Issa, Steve T. Meikle, Stuart L. James, and Ian R. Cooper Copyright © 2014 Rahaf Issa et al. All rights reserved.