bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigations of the Decorative Techniques and Conservation Condition of a Majolica Altar by Andrea della Robbia
Authors: Ombelli Michela , Miliani Costanza , Morresi Assunta 
Published: April 2011

ABSTRACTA multi-disciplinary approach that involved chemical and microstructural characterization was used to aid technological interpretation and conservation condition evaluation and treatment of a della Robbia ceramic masterpiece. The majolica altar was manufactured by Andrea della Robbia in 1490 and has been preserved at St. Mary of the Angels in Assisi, Perugia, Italy. This study characterized the glaze and pigments used by the artist, and furthermore, presents information used to establish guidelines for restoration.
RECENT CASE STUDIES IN THE RAMAN ANALYSIS OF ANCIENT CERAMICS: Glaze Opacification in Abbasid Pottery, Medici and 18th century French Porcelains, Iznik and Kûtayha Ottoman Fritwares and an Unexpected Lapis Lazuli Pigment in Lajvardina Wares
Authors: Colomban Ph. 
Published: April 2011

ABSTRACTWe demonstrate the potential of Raman spectroscopy as an on-site technique for the characterization of ancient ceramics. This non-destructive analysis offers a way to get information on the process and even sometimes on the date of ancient artifacts. Much information remains written in the microstructure of ceramics bodies and in the nanostructure of glasses, glaze and enamels. Raman signatures are specific to the technology that was applied to a given starting batch and to the process of manufacture. Recent studies that demonstrate: i) the use of cassiterite for opacification and its role in Islamic three-color wares and polychrome lustred pottery from the Abbasid to Fatimid period, ii) the invention of the “hybrid-paste porcelain” by the Duke of Medici, known as Medici porcelain and of the “soft-paste” porcelain by the French Manufactures in the eighteen century (Chantilly, Mennecy, Saint-Cloud), iii) the development of the underglaze pigment technology by Iznik and then Kütayha Ottoman potters; iii) the use of lapis lazuli gem as an unexpected pigment in the Iran Lajvardina wares. Finally we explore the relationship between glass makers and potters.
Morphological and Chemical Analyses of Manganese Dioxide Accretions on Mexican Ceramics
Authors: O'Grady Caitlin R. 
Published: April 2011

ABSTRACTMicroscopic analysis of West Mexican ceramics (dating between in the collection of the Department of the Arts of Africa, Oceania and the Americas at the Metropolitan Museum of Art has established five different morphological types of manganese dioxide (MnO2) accretions. The accretions result mostly from a combination of bacterial and weathering activity in post-depositional contexts. Optical microscopy, scanning electron microscopy with energy dispersive x-ray analysis (SEM-EDS) and x-ray fluorescence (XRF) were successful; whereas microchemical spot tests, x-ray diffraction (XRD) and Raman spectroscopy proved inconclusive in the identification and differentiation of the five morphologies. Accretion morphology and substrate characteristics, together, suggest scenarios for the mechanism of formation and offer a qualitative tool for authentication. Accretions were documented using photomicrography, categorized based on empirical observations; sampled and analyzed using SEM-EDS and ND-XRF.
Spontaneous Formation of Ridges on Patterned Mesas and Their Role in the Evolution of
Authors: Arrays Step , Chang Kee-Chul , Blakely Jack M. 
Published: April 2011

ABSTRACTMesa structures fabricated on Si(111) surfaces have been found experimentally to develop step arrays with large spacing of the order of a micron or more after annealing at temperatures where sublimation becomes important. Ridges around the edges initially develop during annealing and form barriers to step motion before eventually breaking down. This produces an array of steps of the same sign with a few wide terraces. Computer simulations using one dimensional Burton, Cabrera and Frank (BCF) theory including attachment-detachment rates and step-step repulsion for this configuration show that the terraces evolve under different dynamics depending on the terrace widths. For large terrace widths, sublimation dominates the step dynamics and the Ehrlich-Schwoebel effect is negligible. Sinusoidal terrace width distributions result in this case. The experimentally measured step distribution has such a sinusoidal shape suggesting that the step dynamics is sublimation dominated on the mesas after ridge breakdown.
Electronic excitations of stable fullerene-like GaP clusters
Authors: Malloci Giuliano , Cappellini Giancarlo , Mulas Giacomo , Satta Guido 
Published: April 2011

ABSTRACTWe present quasi-particle (QP) corrections to the electronic energies for small GaP fullerenes, a new class of nanoscaled materials predicted to be stable and to show spontaneous formation. Using Time-Dependent Density Functional Theory we also computed the optical absorption spectra. The comparison between single-particle and optical absorption spectra yields strong excitonic effects with bonding energy up to 3.5 eV. The QP corrected HOMO-LUMO energy gaps confirm the high stability predicted for such molecules using ground-state computational schemes. The present results can be useful to identify the successful synthesis of these systems via optical absorption and QP spectra.
Simulation of the Organization of Heteroepitaxial Monolayer Islands Under Anisotropic Conditions
Authors: Pandey Gajendra , Kukta Robert V. 
Published: April 2011

ABSTRACTThis paper addresses the effect of anisotropy on the organization of epitaxial islands deposited on a substrate. Focus is on in-plane anisotropies in surface stress and lattice mismatch between the film and substrate materials. Starting from a configuration where island sizes and position are random, evolution towards equilibrium through mass transport via condensation/evaporation is simulated. The effect of the degree of anisotropy is investigated. An efficient numerical method is obtained by reducing a model of square monolayer islands of finite size to point defects that interact through their elastic fields. Models for both the kinetics and energetics of the system are obtained by this reduction. It is found that the point source model is accurate for island separations larger than about 3 times the width of an island. Under isotropic conditions islands tend to form into hexagonal arrays, and as there is no preferred orientation of these arrays, defects analogous to grain boundaries in a crystalline material tend to arise. With anisotropy islands tend to align in particular directions. This is found to enhance organization in cases of modest anisotropy and cause islands to form into zigzagged lines in cases of high anisotropy.
Integration of nanocrystal quantum dots with crystalline semiconductor substrates: Structure, Stability, and Optical response
Authors: Konkar Atul , Lu Siyuan , Madhukar Anupam , Hughes Steven. M. , Paul Alivisatos A. 
Published: April 2011

ABSTRACTIntegration of epitaxical and colloidal semiconductor nanostructures into hybrid structures can potentially open unprecedented functionalities and applications. We present here some results of a study of the structural and optical nature of adsorbed InAs nanocrystal quantum dots (NCQDs) on GaAs(001) substrates containing buried nanostructures, providing the first evidence of excitation transfer from NCQDs to the substrate. Results are also presented for the overgrowth of GaAs on the InAs NCQDs, addressing the all important issue of approach to removal of the chemical contamination left behind by the solvent during adsorption of the NCQDS. It is shown that high structural and optical quality buried integrated structures are feasible, thus opening a new field of investigation.
Enhanced Solubility of Cu in Ag Nanoparticles Synthesized by Inert Gas Condensation
Authors: Ceylan Abdullah , Ni C. , Ismat Shah S. 
Published: April 2011

ABSTRACTAg-Cu alloy nanoparticles were prepared by rapid condensation of metal flux obtained by the simultaneous evaporation of high purity Cu and Ag wires on a tungsten boat in the presence of circulating He gas. Structural properties of the samples prepared at different conditions were investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area diffraction (SAD) patterns. X-ray diffraction patterns showed that particles were phase separated. The particle size obtained either from Scherer's formula or the TEM images show no systematic change on the size of either Cu or Ag particles in the evaporation temperature range between 800 and 1400 °C. By using lattice constant values and Vegard's law, the composition of the particles was calculated to be 6.6 vol% Cu in Ag. Electron diffraction images revealed that particles were softly agglomerated; these electron diffraction results were also consistent with XRD results regarding phase separation. Individual diffraction rings of the Cu and Ag were observed in the SAD patterns.
Atmospheric Stability of E-Beam Deposited Optical Thin Film Stacks
Authors: Hou Ping , Sun Lianchao , Luo Fei 
Published: April 2011

ABSTRACTOptical thin films with SiO2-TiO2 stack were prepared by the technology of electron beam (e-beam) evaporation with ion beam assistant deposition (IBAD). The mechanical (stress) and optical properties of as-deposited thin films were studied as a function of exposure time in the atmospheric environment. Exposing to the air at the ambient temperature causes incremental compressive stress and spectrum profile changes, which is related to the absorption of water moisture into the films. Making a dense film is, therefore, a practical approach to improve structural stability of thin films and then the performance of optical devices.
Failure of brittle functional layers in flexible electronic devices
Authors: Goede Judith de , Bouten Piet , Médico Léonard , Leterrier Yves , Månson Jan-Anders , Nisato Giovanni 
Published: April 2011

ABSTRACTIn the present study, 90 nm thick conducting tin-doped indium oxide (ITO) layers on polymer substrates are used to study the failure behaviour of brittle layers. In a two-point bending test the resistance of uniform ITO-layers and narrow ITO-lines (10 to 300 μm width) are determined as a function of the applied tensile strain. At a certain strain, the thin layer will crack and the resistance will strongly increase. This characteristic strain is analysed using a large number of samples. Early stages of crack development are studied in the fragmentation test. This paper presents the results of different failure mechanisms of thin brittle layers on the electrical conductivity of ITO-layers. When the strain in the ITO-layer increases, stable cracks of a limited length are initiated at defects in the layer (crack initiation). At the critical strain εpthe crack is no longer stable and it will propagate over the whole width of the layer (crack propagation). The experiments show a wide failure strain distribution for narrow ITO-lines. The wide distribution of defects, determining the crack initiation strain, controls the failure of narrow lines. The uniform layers show a narrow failure strain distribution. This is determined by the well-defined crack propagation strain εp.
Magnetic properties of submicron Ni-Mn-Ga martensitic thin films1
Authors: Kohl M. , Chernenko V.A. , Ohtsuka M. , Reuter H. , Takagi T. 
Published: April 2011

ABSTRACTTwo series of Ni-Mn-Ga thin films with two different compositions and various thicknesses in the submicron range are investigated with respect to their structural and magnetic properties. The films are fabricated by sputter deposition on alumina substrates and subsequent heat treatment. The martensitic transformation occurs well above room temperature showing a small thermal hysteresis width of about 6 K. The magnetic properties turn out to be thickness-dependent in the submicron range. In particular, in-plane magnetic susceptibilities increase and critical field strengths for onset of saturation decrease for decreasing thickness down to 0.1 μm by factors of 3–5 depending on the chemical composition. The Curie temperature TC decreases by about 25 K for samples with TC higher than the martensitic transformation.
Electric Dipole Model and Computer Simulation of the Fracture Behavior of a Conductive Crack in a Dielectric Material
Authors: Wang Tianhong , Gao Xiaosheng 
Published: April 2011

ABSTRACTFracture tests on poled and depoled lead zirconate titanate (PZT) ceramics indicate that purely electric fields are able to propagate the conductive cracks (notches) and fracture the samples. To understand the fracture behavior of conducting cracks in ferroelectric ceramics, an electric dipole model is proposed, in which a discrete electric dipole is used to represent the local spontaneous polarization and the force couples are used to represent the local strains. The electric dipole model provides basic solutions for microstructural modeling. The microstructural modeling is based on a domain switching mechanism. The domain structure is simulated with a grid of points where polarizations and strains vary with the applied loads. As a first step study, the microstructural modeling is conducted for a dielectric material with a conductive crack. The simulation result explains why the electric fracture toughness is much higher than the mechanical fracture toughness.
Optimizing the Thermomechanics of Shape-Memory Polymers for Biomedical Applications
Authors: Yakacki Christopher M. , Gall Ken , Shandas Robin , Ortega Alicia M. , Willett Nick , Greenberg Alan R. 
Published: April 2011

ABSTRACTWe examine the shape-memory effect in polymer networks intended for biomedical applications. The polymers were photopolymerized from tert-butyl acrylate (tBA) with polyethyleneglycol dimethacrylate (PEGDMA) acting as a crosslinker. Three-point flexural tests were used to systematically investigate the thermomechanics of shape-storage deformation and shape recovery. The glass transition temperature (Tg) of the polymers varied over a range of 100°C and is dependent on the molecular weight and concentration of the crosslinker. The polymers show 100% strain recovery up to maximum strains of approximately 80% at low and high deformation temperatures (Td). Free strain recovery was determined to depend on the temperature during deformation; lower deformation temperatures (Td < Tg) decreased the temperature required for free strain recovery. Constrained stress recovery shows a complex evolution as a function of temperature and also depends on Td. The thermomechanical results are discussed in light of potential biomedical applications and a prototype stent that can be activated at body temperature is presented.
Parametric Study of Single-Walled Carbon Nanotubes Using Alcohol Catalytic Chemical Vapor Deposition
Authors: Emrah Unalan H. , Chhowalla Manish 
Published: April 2011

ABSTRACTSingle-walled carbon nanotubes (SWNTs) were synthesized both in powder form and on substrates using alcohol catalytic chemical vapor deposition method (ACCVD). A detailed parametric study was conducted. As-grown SWNTs were analyzed using transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FE-SEM) and Raman spectroscopy. Nucleation and growth of SWNTs occurred within seconds after introduction of the alcohol vapor. The results show that high quality SWNTs with a narrow diameter distribution without amorphous carbon can be grown using Co acetate catalyst doped with Fe acetate above 750°C. Defective nanotubes were observed at low (450°C) and high (950°C) temperatures with the optimum temperature being 850°C. In brief, our work has taken a step towards optimizing SWNTs growth conditions using ACCVD.
Resonance Raman Spectroscopy to Study and Characterize Defects on Carbon Nanotubes and other Nano-Graphite Systems
Authors: Jorio Ado , Cançado Luiz Gustavo , Neves Bernardo R. A. , Souza Mauricio de , Fantini Cristiano , Pimenta Marcos A. , Medeiros-Ribeiro G. , Samsonidze Georgii G. , Chou Shin Grace , Dresselhaus Gene , Dresselhaus Mildred S. , Rao A. M. , Grüneis Alexander , Saito Riichiro 
Published: April 2011

ABSTRACTThe use of resonance Raman spectroscopy (RRS) to study and characterize single wall carbon nanotubes (SWNTs) is discussed, focusing on preliminary efforts for the development of the RRS to characterize defects in SWNTs. The disorder-induced D-band, disorder-induced peaks just above the first-order allowed graphite G-band, as well as the intermediate frequency modes (IFMs) appearing between the RBM and the D/G spectral region are addressed. RRS on nanographite ribbons and on a step-like defect in highly ordered pyrolytic graphite (HOPG) sheds light into the problem of characterizing specific defects in nano-related carbons.
Self-Organization of Semiconductor Quantum Nanocrystals on Carbon Single-Wall Nanotubes into Close-Packed Linear Arrays
Authors: Engtrakul C. , Nedeljkovic J. M. , Kim Y.-H. , Ahrenkiel S. P. , Gilbert K. E. H. , Alleman J. L. , Zhang S. B. , Micic O. I. , Nozik A. J. , Heben M. J. 
Published: April 2011

ABSTRACTWe report the synthesis of organized colloidal semiconductor nanocrystal / carbon singlewalled nanotube hybrid nanostructures. The synthetic protocol described here avoids the need for covalent chemical modification of carbon nanotube (CNT) surfaces. Specifically, InP quantum dots (QDs) and CdSe QDs were found to strongly adsorb onto the surfaces of carbon single-walled nanotubes (SWNTs) by gentle heating in organic solvents. Transmission electron microscopy (TEM) was used to characterize the semiconductor nanocrystal (NC) / SWNT assemblies, and revealed that the surfaces of the SWNT bundles template the adsorption of the NCs from solution. Small QDs were found to randomly absorb onto SWNTs, while larger QDs self-assembled into long linear chains. The nature of binding and ordering was investigated by simply considering van der Waals (vdW) forces for both NC-SWNT and NC-NC interactions. Quantum rods (QRs) were also found to adsorb along the nanotube surfaces. These findings have important implications for the synthesis of NC / SWNT hybrid nanostructures.
Probing the Phonon-Assisted Relaxation Processes in DNA-wrapped Carbon Nanotubes Using Photoluminescence Spectroscopy
Authors: Chou S. G. , Plentz F. , Jiang J. , Saito R. , Nezich D. , Ribeiro H. B. , Jorio A. , Pimenta M. A. , Samsonidze Ge. G. , Santos A. P. , Zheng M. , Onoa G. B. , Semke E. D. , Dresselhaus G. , Dresselhaus M. S. 
Published: April 2011

AbstractWe present a detailed photoluminescence study of a (6, 5) enriched DNA-wrapped single wall carbon nanotube (DNA-CNT) solid sample and an as-produced DNA-CNT solution. Multiple strong PL peaks were observed at excitation energies that do not correspond to the interband electronic transitions that are strongly enhanced by electronic van Hove singularities. These strong PL peaks are assigned to different mechanisms of excitation and relaxation, including one phonon, two phonon, hot luminescence processes, as well as radiative and non-radiative energy transferring mechanisms between neighboring nanotubes. These processes are assigned to different channels of phonon-assisted electron relaxation. The study shows that the electronic relaxation processes observed in PL can be used as a means to probe different physical interactions between photons, electrons, and phonons that are not separately identified in bulk semiconducting materials.
Solubility and Electrical Response of Single Walled Carbon Nanotubes with Thiolate Mediated Gold Nanoparticle Attachment
Authors: Cui Jingbiao , Daghlian Charles P. , Gibson Ursula J. 
Published: April 2011

ABSTRACTDodecanethiol-stabilized-Au nanoparticles are successfully attached to the sidewall of as-grown single walled carbon nanotubes (SWCNTs) via a simple approach. This provides a straightforward method to functionalize and dissolve SWCNTs of full length in organic solvents. The modified nanotubes exhibit dramatic increase in tube resistance and strong gate dependence with a memory effect, which is explained in terms of nanotube structure deformation induced by surface thiolation. The mechanism for Au particle attachment is shown to be via dodecanethiol groups.
Electrophoretic Deposition of Carbon Nanotubes into Device Structures: An Approach to Integrate Nanostructures into Micro devices
Authors: Guduru Madhuri , Francis Anand , Dobbins Tabbetha A. 
Published: April 2011

ABSTRACTCharged particles in suspension tend to move when an electric field is applied. This simple phenomenon of migration of charged particles in a liquid medium and their subsequent deposition onto an oppositely charged electrode is called electrophoretic deposition (EPD), and is used in assembly of nanoparticles into microfabricated devices. This work reports the application of the EPD process for deposition of commercially available purified single-walled carbon nanotubes (CNT) onto microfabricated device structures. A direct current EPD in aqueous medium was used to position CNTs into two different microfabricated device structures: gold electrodes of 100nm thickness and gold microcantilevers. Control of the mass of CNTs deposited using EPD process is addressed in this work.
Matchstick Nanotubes: Structure Control and Properties
Authors: Jourdain Vincent , Paillet Matthieu , Poncharal Philippe , Zahab Ahmed , Loiseau Annick , Bernier Patrick , Robertson John 
Published: April 2011

ABSTRACTWe report here on the catalyst features found critical in order to induce the growth of matchstick nanotubes by a sequential catalytic growth mechanism. The presence of phosphorus is required to form metal phosphide particles active for the formation of carbon nanotubes with a matchstick morphology. The metal composition does not influence the nanofilament type but strongly affect the nanotube yield. Original properties of these new periodic nanostructures are also highlighted, such as the preferential breaking at the thin nanomatch interjunctions, giving rise to individual nanomatches in suspension after ultrasonic treatment. The possibility to use this mechanism to insert carbon nanotubes with ferromagnetic nanoparticles is also reported.
On the Flexural Characteristics of Multi-walled Carbon Nanotubes
Authors: Bai Rong , Molenaur Justin , Byron Pipes R. 
Published: April 2011

ABSTRACTWe use an analytical solution for bending of coaxial orthotropic cylinders to model the flexural deformation of multi-walled nanotubes with any number of layers. The simulation results show that the bending stiffness of the MWNT increases with the number of nanotube layers. For fixed number of layers, MWNT with larger inner radius has greater bending stiffness. The bending stiffness also increases with out layer radius. For certain outer radius, smaller inner radius results in a larger stiffness. The effective elastic modulus of the MWNT also increases with the number of layers and the outer radius. For the same value of the outer radius, the MWNT with smaller inner radius has a larger effective elastic modulus. As the number of layers increases, the effective modulus approaches the in-plane elastic modulus of graphene. In this work we find that the interface conditions, i.e., perfect bonding or no friction, do not affect the bending stiffness and effective elastic modulus of the MWNT. Furthermore, the cross-section of MWNT does not show any warping under bending, which suggest the classic beam theory is applicable in determining the flexural response of MWNT.