bluuebunny/crossref_metadata_2025_split huggingface dataset:
Room temperature Strong coupling in low finesse GaN microcavities
Authors: Sellers Ian , Semond Fabrice , Leroux Mathieu , Massies Jean , Disseix Pierre , Malpuech Guillaume , Henneghien A-L. , Leymarie Joel , Vasson A 
Published: April 2011

AbstractWe present experimental results demonstrating strong-light matter coupling at low and room temperature in bulk GaN microcavities. Angle dependent reflectivity measurements demonstrate strong-coupling with a Rabi-energy of 50meV at room temperature which is well reproduced with transfer matrix simulations. The absence of strong coupling in the photoluminescence is attributed to the low finesse of the microcavity (Q=60) and is confirmed by simulations which indicate a quality factor of 90 is required to observe strong-coupling in the emission.
Surface Recombination and Vacuum/GaN/AlGaN Surface Quantum Wells
Authors: Zhang Xiyao , Wellenius Ian Patrick , Cai Ailing , Muth John , Roberts John , Rajagopal Pradeep , Cook Jim , Piner Eddie , Linthicum Kevin 
Published: April 2011

AbstractSurface quantum wells of gallium nitride have been grown by Metal Organic Vapor Phase Epitaxy on top of AlGaN/GaN heterostructures. One boundary of the quantum well is vacuum (or air)/GaN interface, the other is GaN/AlGaN interface, and the width of the quantum well is the thickness of gallium nitride cap, and quantum confinement is demonstrate by the energy shift in photoluminescence, and cathodoluminescence as the GaN cap thickness is varied. The efficiency of the quantum well emission is sensitive to the surface environment and resulting surface recombination velocity. In this study the surface is altered by surface preparation treatments and resulting in changes in the luminescence. The changes in the efficiency of quantum well luminescence with surface treatments are attributed to changes in surface recombination velocity and surface electric fields.
A microspectroscopic study of cap damage in annealed RE-doped AlN-capped GaN
Authors: Nogales Emilio , Lorenz K. , Wang K. , Roqan I.S. , Martin R.W. , O'Donnell K.P. , Alves E. , Ruffenach S. , Briot O. 
Published: April 2011

AbstractIntegrated AlN nanocaps are used to protect gallium nitride epilayers during high temperature annealing treatments following high-energy implantation of rare earth (RE) ions. Cracks formed in thicker caps due to the lattice mismatch between AlN and GaN lead to the creation of microscopic surface defects at annealing temperatures higher than around 1200 °C. GaN dissociates locally to produce holes in the caps. Simultaneous cathodoluminescence/wavelength dispersive X-ray microanalysis in a modified electron probe microanalyzer allows study of the compositional and light emission variations near these microscopic defects. The intensity of the 5D0 – 7F2 transition related emission is enhanced and spectral changes can be observed, which indicate changes in the structure and/or composition of a very thin layer that forms the walls of holes in the caps. We also report some preliminary observations on the influence of the annealing atmosphere (nitrogen or ammonia) on cap damage.
Environmental Impact of Crystalline Silicon Photovoltaic Module Production
Authors: Alsema Erik , de Wild Mariska J 
Published: April 2011

AbstractTogether with a number of PV companies an extensive effort has been made to collect Life Cycle Inventory data that represents the current status of production technology for crystalline silicon modules. The new data covers all processes from silicon feedstock production to cell and module manufacturing. All commercial wafer technologies are covered, that is multi- and monocrystalline wafers as well as ribbon technology. The presented data should be representative for the technology status in 2004, although for monocrystalline Si crystallisation further improvement of the data quality is recommended. On the basis of the new data it is shown that PV systems on the basis of c-Si technology are in a good position to compete with other energy technologies. Energy Pay-Back Times of 1.7-2.7 yr are found for South-European locations, while life-cycle CO2 emission is in the 30-46 g/kWh range. Clear perspectives exist for further improvements with roughly 40-50%.
Life Cycle Analysis of Solar Module Recycling Process
Authors: Müller Anja , Wambach Karsten , Alsema Erik 
Published: April 2011

AbstractSince June 2003 Deutsche Solar AG is operating a recycling plant for modules with crystalline cells. The aim of the process is to recover the silicon wafers so that they can be reprocessed and integrated in modules again. The aims of the Life Cycle Analysis of the mentioned process are (i) the verification if the process is beneficial regarding environmental aspects, (ii) the comparison to other end-of-life scenarios, (iii) the ability to include the end-of-life phase of modules in future LCA of photovoltaic modules. The results show that the recycling process makes good ecological sense, because the environmental burden during the production phase of reusable components is higher than the burden due to the recycling process. Moreover the Energy Pay Back Time of modules with recycled cells was determined.
Novel Energetic Composite Materials
Authors: Nable Jun , Mercado Andrew , Sherman Andrew 
Published: April 2011

AbstractA screening of novel energetic materials is presented. These materials are selected according to their energy content and heat release during ignition. These material mixtures will be fabricated into composites that can also perform structural functions. A composite fabrication route is developed using fluidized bed chemical vapor deposition; coating a metallic layer onto the particles as a method to control mechanical properties and reaction kinetics. These reactive metal matrix composites can be developed to offer optimum performance with specific strength, modulus and energetic capabilities.
Towards Cyclophosphazene Based Dendrimers For Energetic Binders
Authors: Greenland Barny , Steinke Joachim H. G. , Widdowson David A. , Golding Peter , Trussell Steve 
Published: April 2011

AbstractDendrons and dendrimers containing cyclophosphazenes units in each generation have been synthesised by the convergent route for the first time. We also demonstrate the synthesis of dendrons containing precise numbers of benzyl protected alcohol functionalities.
Ignition of Aerosolized Reactive Particles at High Heating Rates
Authors: Mohan Salil , Shoshin Yuriy L , Dreizin Edward L 
Published: April 2011

AbstractThis paper presents an experimental methodology, respective heat transfer model, and initial results describing ignition of rapidly heated, aerosolized powders of different materials. The experimental setup uses a CO2 laser as a heat source. The interaction of the laser beam with particles is particle size-dependent and only a narrow range of particle sizes is heated effectively. Therefore, the heat transfer model needs to be only analyzed for the particles with this specific size, which greatly simplifies the interpretation of experiments. The powder is aerosolized inside a plate capacitor by charging particles contacting the capacitor’s electrodes. A thin, laminar aerosol jet is carried out by an oxidizing gas through a small opening in the top electrode and is fed into a laser beam. The velocities of particles in the jet are about 1 m/s. The laser power is increased until the particles are observed to ignite. The ignition is detected optically. The ignition thresholds for spherical magnesium and aluminum powders were measured. The experimental data for magnesium, for which ignition kinetics is well known, were used to calibrate the detailed heat transfer model. The model was used to evaluate the ignition kinetics for aluminum powder.
Dynamic Impact Characterization of Al+Fe2O3+30% Epoxy Composites Using Time Synchronized High-Speed Camera and VISAR Measurements
Authors: Ferranti Louis , Thadhani Naresh N. 
Published: April 2011

AbstractReverse Taylor anvil-on-rod impact experiments were conducted on Al+Fe2O3+30% epoxy composites to measure their viscoelastic and fracture response to dynamic loading. Impact velocities ranged from 80 to 200 m/s. High-speed camera images capturing transient deformation reveal these materials exhibit significant elastic recovery in both the longitudinal and radial directions. Images were time synchronized with free surface velocity measurements, using VISAR, to track elastic/plastic wave interactions attributed to the material’s dynamic loading response. Some specimens underwent brittle fracture once a critical areal strain was exceeded while the axial strain response appeared unaltered.
A Multi-Phasic, Continuum Damage Mechanics Model of Mechanically Induced Increased Permeability in Tissues
Authors: O’Neill Brian , Quinn Timothy P , Frenkel Victor , Li King C P 
Published: April 2011

AbstractRecently, we have reported enhanced permeability of tissues due to in vivo treatment with pulsed high intensity focused ultrasound (pHIFU). This new therapy has shown promise as a way of increasing the penetration of large drug molecules, both out of the vasculature and through the tissue. To date, no clear physical model of tissue exists that can account for these effects.A new model is proposed that clearly establishes the link between tissue structure and fluid flow properties on one hand, and the history of applied mechanical forces on the other. The model draws inspiration from two different theoretical fields of materials science, multi-phase theory and continuum damage mechanics. The theory differs from the traditional bi-phasic solid-fluid model of tissues in that the fluid part here is broken into trapped (moving with the solid) and free (moving through the solid) parts. A damage-like variable links the effective elasticity of the tissue to the ratio of the trapped to free fluids. As the damage increases, the tissue becomes, in effect, less stiff and more permeable. Release of elastic energy drives the process. A distribution of energy barriers opposes the process and governs how the fluid is released as damage increases.
Micromechanical and Structural Analysis of Compromised Dental Tissues
Authors: Mahoney Erin , Kilpatrick Nicky , Swain Michael 
Published: April 2011

AbstractWith the continual development of new dental materials and treatment techniques, dental materials research is now more important than ever. Although the traditional method of materials and treatment technique assessment was laboratory based, there is a need for investigations into the clinical outcomes of in-vitro research. The aim of this paper is to discuss the micromechanical and structural analysis of compromised dental tissues that affect young children, using a biomaterial and clinical approach.
Biphasic composite of Tricalcium phosphate reinforced with Hydroxyapatite Whiskers
Authors: Viswanath B , Narayanan Ravishankar 
Published: April 2011

AbstractBiphasic calcium phosphates have received considerable attention due to their optimum dissolution rate in the human body after implantation. These materials are composed of hydroxyapatite (HA) and resorbable tricalcium phosphate (TCP). In the present investigation, HA whiskers are reinforced into TCP to enhance the mechanical properties of this biphasic composite. Various amounts (30-50 wt%) HA whiskers are reinforced in TCP matrix. Microstructural characterization has been carried out using field-emission scanning electron microscope. Mechanical properties have been investigated by microindentation in a universal testing machine (UTM). As TCP is resorbable, it will dissolve in body fluid and there is a strong possibility for the faceted HA whiskers to interact with functional groups present in the body fluid surroundings.
Nanoindentation Measurements of Bone Viscoelasticity as a Function of Hydration State
Authors: Bembey Amanpreet Kaur , Oyen Michelle , Bushby Andrew , Boyde Alan 
Published: April 2011

AbstractBone is an anisotropic material, and its mechanical properties are determined by its microstructure as well as its composition. Mechanical properties of bone are a consequence of the proportions of, and the interactions between, mineral, collagen and water. Water plays an important role in maintaining the mechanical integrity of the composite, but the manner in which water interacts within the ultrastructure is unclear. Dentine being an isotropic two-dimensional structure presents a homogenous composite to examine the dehydration effects. Nanoindentation methods for determining the viscoelastic properties have recently been developed and are a subject of great interest. Here, one method based on elastic-viscoelastic correspondence for ‘ramp and hold’ creep testing (Oyen, J. Mater. Res., 2005) has been used to analyze viscoelastic behavior of polymeric and biological materials. The method of ‘ramp and hold’ allows the shear modulus at time zero to be determined from fitting of the displacement during the maximum load hold. Changes in the viscoelastic properties of bone and dentine were examined as the material was systematically dehydrated in a series of water:solvent mixes. Samples of equine dentine were sectioned and cryo-polished. Shear modulus was obtained by nanoindentation using spherical indenters with a maximum load hold of 120s. Samples were tested in different solvent concentrations sequentially, 70% ethanol to 50% ethanol, 70 % ethanol to 100% ethanol, 70% ethanol to 70% methanol to 100% methanol, and 70% ethanol to 100% acetone, after storage in each condition for 24h. By selectively removing and then replacing water from the composite, insights in to the ultrastructure of the tissue can be gained from the corresponding changes in the experimentally determined moduli, as well as an understanding of the complete reversibility of the dehydration process.
Effects of gelatin on mechanical properties of hydroxyapatite-gelatin nano-composites
Authors: Ko Ching-Chang , Oyen Michelle , Fallgatter Alison M , Hu Wei-Shou 
Published: April 2011

AbstractA biomimetic reactor has been developed to synthesize hydroxyapatite-gelatin (HAP-GEL) nanocomposites that mimic ultra-structures of natural bone. We hypothesize that in the reactor, gelatin concentration controls morphology and packing structures of HAP crystals. To test the hypothesis, three types of mechanical tests were conducted, including nanoindentation, compression, and fracture tests. Nanoindentation tests in conjunction with computer modeling were used to assess effects on gelatin-induced microstructures of HAP. The results showed that increasing gelatin content increased both the plane strain modulus and the fracture toughness. The gelatin appeared to shorten the HAP crystal distance, which consolidated the internal structure of the composite and made the material more rigid. The fracture toughness KIC increased partially due to the effect of fiber bridging between gelatin molecules. The highest fracture toughness (1.12 MPa·m1/2) was equivalent to that of pure hydroxyapatite. The compressive strength of the HAP-GEL (107.7±6.8 MPa) was, however, less sensitive to microstructural changes and was within the range of natural cortical bone (human 170 MPa, pig: 100 MPa). The compression strength was dominated by void inclusions while the nanoindentation response reflected ultra-structural arrangement of the crystals. The gelatin concentration is likely to modify crystal arrangement as demonstrated in TEM experiments but not void distribution at macroscopic levels.
Role of Interfacial Interactions on Mechanical Properties of Biomimetic Composites for Bone Tissue Engineering
Authors: Verma Devendra , Bhowmik Rahul , Mohanty Bedabibhas , Katti Dinesh R , Katti Kalpana S 
Published: April 2011

AbstractInterfaces play an important role in controlling the mechanical properties of composites. Optimum mechanical strength of scaffolds is of prime importance for bone tissue engineering. In the present work, molecular dynamics simulations and experimental studies have been conducted to study effect of interfacial interactions on mechanical properties of composites for bone replacement. In order to mimic biological processes, hydroxyapatite (HAP) is mineralized in presence of polyacrylic acid (PAAc) (in situ HAP). Further, solid and porous composites of in situ HAP with polycaprolactone (PCL) are made. Mechanical tests of composites of in situ HAP with PAAc have shown improved strain recovery, higher modulus/density ratio and also improved mechanical response in simulated body fluid (SBF). Simulation studies indicate potential for calcium bridging between –COO− of PAAc and surface calcium of HAP. This fact is also supported by infrared spectroscopic studies. PAAc modified surfaces of in situ HAP offer means to control the microstructure and mechanical response of porous composites. Nanoindentation experiments indicate that apatite grown on in situ HAP/PCL composites from SBF has improved elastic modulus and hardness. This work gives insight into the interfacial mechanisms responsible for mechanical response as well as bioactivity in biomaterials.
Influence of Strain Rate on the Mechanical Behaviour of Human Interstitial Bone at the Microstructural Level
Authors: Maximilien Vanleene , Pierre-Emmanuel Mazeran , Marie-Christine Ho Ba Tho 
Published: April 2011

AbstractInvestigation of bone mechanical properties is of importance for bone pathology researches, development of biomaterials and prosthesis. Due to the bone complex multi-scale structure, assessment of bone microstructure is an important step of bone mechanical behaviour understanding. In this study, we performed dynamic nanoindentation tests in order to investigate visco-plastic and visco-elastic properties of bone interstitial lamellae.
A Theoretical Basis for Biomimetics
Authors: Vincent Julian , Bogatyreva Olga , Bogatyrev Nikolay , Pahl Anja-Karina , Bowyer Adrian 
Published: April 2011

AbstractThe Russian “Theory of Inventive Problem Solving” was developed to solve technological problems, but it can equally well be applied to biology and the way organisms have solved similar problems. As such it can also be used to bridge the gap between biology and engineering, and to provide a theoretical basis for Biomimetics.
Modeling receptor-mediated endocytosis via mechanics of cell adhesion
Authors: Shi Wendong , Gao Huajian , Freund Lambert Ben 
Published: April 2011

AbstractA mathematical model describing how a cell membrane with diffusive mobile receptors wraps around a ligand coated cylindrical or spherical particle has been recently developed to model particle size effects in receptor mediated endocytosis. The model predicted an optimal particle size for the smallest wrapping time, as well as a minimum and a maximum particle size for successful wrapping. The results showed that particles in the size range of tens to hundreds of nanometers can enter cells even in the absence of clathrin or caveolin coats. Here we report some further progresses on modeling a spontaneous membrane curvature induced by clathrin or caveolin coats at the inner membrane leaflet as well as simultaneous entry of many particles into cells. It is found that a spontaneous membrane curvature narrows the particle size range for successful wrapping and there exists an optimal particle density for maximum particle adsorptivity.
Crystalline TiO2 Macrocellular Foams with Highly Nano-Mesoporous Framework
Authors: Carn Florent , Reculusa Stéphane , Deleuze Hervé , Backov Rénal 
Published: April 2011

AbstractTitanium dioxide macro-cellular monolith-type materials have been obtained with emphases toward controlling porosity at the meso- and macroscopic length scales, leading thus to hierarchically organized porous architectures. First, at the microscopic length scale, either monophasic Anatase, biphasic Anatase-Rutile or monophasic Rutile allotropic forms are generated by varying the applied thermal treatment. At the meso- and/or nanoscopic length scales either lyotropic templates or latex colloids have been used to promote meso- or super-mesoporosity. Particularly, a Pluronic copolymer P-123 combined with cationic surfactant (TTAB) induces vermicular-like mesoporosity associated with a specific surface area around 450 m2·g-1. At the macroscopic length scale a non-static air-liquid foam strategy allows a strong control over the open-cell morphologies.
Engineered Three-dimensional Colloidal Crystals Containing a Planar Defect
Authors: Massé Pascal , Agricole Beatrice , Sellier Elisabeth , Ravaine Serge 
Published: April 2011

AbstractWe have fabricated three-dimensional (3D) colloidal crystals containing a two-dimensional (2D) defect as the middle layer by the Langmuir-Blodgett (LB) technique. Either a homogeneous sheet made of hundreds layers of behenic acid or a single monolayer of silica colloidal particles of various sizes was inserted between two opal films of silica spheres. The presence of the extrinsic defect led to an impurity mode within the photonic stop band, which was observed as a pass band in the near-infrared (NIR) spectra. The position of this defect mode was found to vary periodically with the value of the ratio of the thickness of the defect layer to the diameter of the colloids of the upper and lower opals.
Nucleation and growth of polymorphs of barbital on chemically modified surfaces in microfluidic channels
Authors: MacDonald John C. , Biyikli Kasim , Zugic Branko , Ebersole Garrett , Allor Joshua 
Published: April 2011

AbstractCrystallization experiments have been carried out in microfluidic devices to screen for polymorphs by crystallization on a range of surfaces. These devices consist of PDMS (polydimethylsiloxane) patterned with microchannels and then bonded to self-assembled monolayers (SAMs) of organic molecules on gold substrates. Barbital was crystallized in microchannels over five different SAMs functionalized with polar and nonpolar organic groups. Growth of polymorphs was examined under thermodynamic conditions from solutions at room temperature and under kinetic conditions by rapid cooling. The results of these experiments and the influence of chemically modified surfaces in microchannels in controlling polymorphism are discussed.
Protein-Directed Self-Assembly of Gold Nanoparticles
Authors: Vertegel Alexey , Shang Wen , Dordick Jonathan , Siegel Richard 
Published: April 2011

AbstractWe have employed protein-protein interactions for controlled assembly of gold nanoparticles. Stoichiometric 1:1 protein:nanoparticle conjugates were prepared for proteins known to strongly interact with each other and these interactions were used to self-assemble nanoparticles. Mixing equivalent amounts of the antigen-nanoparticle and antibody-nanoparticle conjugates resulted in the formation of nanoparticle dimers with a yield of about 60%. Trimers (yield ∼30%) can be obtained by mixing 2:1 antigen-nanoparticle with 1:1 antibody-nanoparticle conjugates in a molar ratio of 1:2. The structures are destroyed at low pH when the antibody-antigen complex dissociates.
Electronic structure of helically coiled carbon nanotubes
Authors: Guzman-Verri Gian Giacomo , Lew Yan Voon Lok C. , Willatzen Morten , Gravesen Jens 
Published: April 2011

AbstractIn the present work we calculate the electronic band structure of single-wall helical carbon nanotubes following an effective-mass approach. We include curvature effects and strain due to bending in the band structure. The curvature energy ΔE, and the change in the electronic energy ΔEs due to strain, depend upon the coil pitch and coil diameter of the tube. We find 0.003 ≤|ΔE|≤ 1.3 eV and 0 ≤ΔEs ≤ 4.0 eV for the single-wall helical carbon nanotubes considered here.
Self-Assembled GdSi2 Nanostructures Grown on Si(001) Studied by TEM and STM
Authors: Ye Gangfeng , Crimp Martin A. , Nogami Jun 
Published: April 2011

AbstractSelf-assembled gadolinium silicide (GdSi2) nanostructures grown on Si(001) were studied by transmission electron microscopy (TEM) and scanning tunneling microscopy (STM). Cross-sectional TEM and plan-view TEM moiré fringe pattern analyses show that the GdSi2 nanostructures can be divided into two classes: elongated nanowires with hexagonal crystal structure and rectangular islands with orthorhombic or tetragonal crystal structure.