bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protein-Drug Interaction in the Nanocomposites Prepared by UV and IR Pulsed Laser Deposition
Authors: Sagawa J. , Nagare S. , Senna M. 
Published: April 2011

ABSTRACTProtein (bovine serum albumin; BSA)-drug (indomethacin; IM) nanocomposites were prepared by pulsed laser deposition (PLD) at two wavelengths, infrared (1064nm) and ultraviolet (266nm), from uniformly dispersed mixture of BSA and IM as a target. Composite particulates under 50nm were obtained with the coexistence of larger agglomerates over 200nm. Primary structure of BSA is preserved after laser irradiation by both wavelengths. Effects of electronic and vibrational excitation by UV and IR laser respectively on the secondary structure of the nanocomposites were examined by Fourier transform infrared spectroscopy (FT-IR). Chemical shift towards lower wavenumber and a broadening of the amide I band due to PLD treatment were observed by FT-IR. From curve fitting of the amide I into five components, we found the decrease in the ratio of α-helical / β-sheet components with increasing the laser fluence. The secondary structure of BSA is more sensitive to the laser fluence than the wavelength.
Heteroepitaxial Self-Assembly of Higher-Complexity Structures By Combining Growth Control with Nanopatterning
Authors: Floro Jerrold A. , Gray Jennifer L. , Atha Surajit , Singh Nitin , Elzey Dana , Hull Robert 
Published: April 2011

ABSTRACTWe provide an overview of a novel self-assembly process that occurrs during GeSi/Si(001) strain-layer heteroepitaxy under conditions of limited adatom mobility. Suppression of copious surface diffusion leads to limited three-dimensional roughening in the form of pits that partially consume a thick, metastable wetting layer. The material ejected from the pits accumulates alongside, eventually forming a symmetric quantum dot molecule consisting of four islands bound to a {105}-faceted pit. These structures, which are of interest in nanologic applications, appear to arise from an intrinsic strain-relief mechanism in a relatively narrow regime of deposition conditions. An additional degree of morphological control is obtained by annealing films containing pits, before they evolve to full quantum dot molecules. Annealing promotes a one-dimensional growth instability leading to the formation of highly anisotropic grooves, bounded by long, wire-like islands. Finally, we show that patterns created in the Si substrate using a focused ion beam can control the location of quantum dot molecules, which is an additional critical step towards being able to use these structures for computing.
Dot Pattern Formation on Silicon Surfaces by Low-Energy Ion Beam Erosion
Authors: Ziberi B. , Frost F. , Höche T. , Rauschenbach B. 
Published: April 2011

ABSTRACTExperimental studies of low-energy (≤ 2000 eV) Ar+ ion beam erosion of Si surfaces under normal and oblique ion incidence with simultaneous sample rotation at room temperature show a variety of topographies. At oblique ion incidence, between 70° and 80° with respect to surface normal, dot patterns evolve (dot size ∼ 30 nm) with a remarkably high degree of ordering comparable to dot nanostructures reported for different III/V compound semiconductors. The mean size and ordering of these nanostructures can be adjusted by various process parameters like ion beam energy and erosion time, respectively. Scanning force microscopy (AFM) has been used to characterize the evolution of the surface topography.
Fabrication and Atomistic Modeling of Ion-Etch Nanostructures on Substrates
Authors: Stepanova Maria , Dew Steven K. 
Published: April 2011

ABSTRACTWe have implemented and investigated numerically a new process to fabricate self-organized metal networks and lines on non-metallic substrates. We have deposited a thin film of Cu on silicon and glass substrates and etched the film by a 1 keV-energy Ar beam. Due to the kinetic mechanism known as sputter instability, nanosize metal patterns self-organize on the substrate at the stage when the etched surface reaches the metal/substrate interface. By numerical simulations, we have investigated the mechanism and control factors for the process.
Leakage Currents through Thin Silicon Oxide Grown on Atomically Flat Silicon Surfaces
Authors: Ignatescu Valerian , Blakely Jack M. 
Published: April 2011

ABSTRACTAtomically flat surfaces can be obtained by high-temperature annealing in UHV of specially patterned silicon samples. Thin silicon oxide layers were grown by dry oxidation on three types of surfaces: (a) atomically flat surfaces, (b) normal (stepped) surfaces cleaned in UHV by the same high-temperature annealing and (c) normal wafer surfaces, which underwent just an RCA chemical cleaning before oxidation. Atomic force microscopy (AFM) was performed to reveal the topography of the surfaces. Aluminum pads were deposited on these oxidized surfaces using photolithography techniques. The leakage current through the oxide was measured for all three cases. Our results show that the smoother the surface before oxidation, the smaller the leakage current.
Physical Self-Assembly And Nano-Patterning
Authors: Lu T.-M. , Ye D.-X. , Karabacak T. , Wang G.-C. 
Published: April 2011

AbstractIt is known that oblique angle deposition (or glancing angle deposition) can create 3D architectures that are otherwise difficult to produce using the conventional lithographic techniques. The technique relies on a self-assembly mechanism originated from a physical shadowing effect during deposition. In this paper we show examples of 3D nanostructures obtained by this oblique angle deposition on a templated substrate with regularly spaced pillar seeds. We show that common to this technique is the phenomenon of side-way growth on the seeds. The side-way growth leads to a fan-like structure at the initial stages of growth if the incident oblique angle is fixed during growth. Simulations based on a steering effect due to the attractive force between the incoming atom and the existing atoms on the surface produce a fanlike structure similar to that observed experimentally. We show that a two-phase substrate rotation scheme during deposition can dramatically reduce this fan-out effect and can lead to uniform and isolated columns.
Large Scale Engineered Nanostructured Surfaces by Reactive Ion Etching with Kinetically Self-Assembled Non-continuous Metal Film as Etching Mask
Authors: Wei Wei , Bachman Mark , Li Guann-Pyng 
Published: April 2011

ABSTRACTIn this study, we explored the possibility of using annealed non-continuous metal film enabled etching technique to produce large nano-structured surfaces. Non-continuous Ag film is deposited on silicon wafer with a thin layer of silicon dioxide using E-beam deposition, and then vacuum thermal annealing was applied on the deposited films, causing nano-scaled Ag particles to migrate and agglomerate into self-assembled islands of larger nanometer dimensions. We controlled the density and average size of the metal islands through thickness of the initial film and subsequent annealing rates. Reactive ion etching through the metal islands mask into the underneath silicon dioxide layer was performed following the annealing process. Preliminary hydrophobicity experiments were carried out using the engineered nano-structured surfaces.
Thermal Deicing of Polymer Composite Helicopter Blades
Authors: Dutta Piyush K. , Ryerson Charles C. , Pergantis Charles 
Published: April 2011

ABSTRACTThis paper presents the results of an investigation to determine if thermal deicing methods (hot air, hot water, hot glycol, or radiative heat) would damage the composite materials in helicopter blades. Samples made from Blackhawk helicopter blades were thermally cycled in the regime of the temperatures of thermal deicing methods and then mechanically load tested. The strength reduction was compared with the number of thermal cycling and the temperatures of thermal cycling. The strength results and the modes of failure indicate that damages indeed do develop in the composites, especially along the bond line of the composite skin and the nomex core of the blade structure, and mechanical strength is reduced.
Syntactic Closed-cell Foams Based on Silicon Carbide
Authors: Ozcivici Engin , Singh Raman P. 
Published: April 2011

ABSTRACTClosed cell foams were fabricated by incorporating two different grades of hollow alumino-silicate spheres (cenospheres) into a silicon carbide matrix. The silicon carbide matrix was formed by the pyrolysis of a preceramic polymer, and multiple polymer infiltration and pyrolysis (PIP) cycles were employed to minimize the open voids in the material. The physical, mechanical and thermal properties of the fabricated foams were characterized as functions of the number of reinfiltration cycles. The open- and closed-void volume fractions were determined by measurements of bulk and skeletal densities. Mechanical properties, including strength and modulus, were evaluated using four-point bend and compression tests. Finally, thermophysical (thermal conductivity) values of the material were determined using laser-flash technique. This processing technique results in closed-cell syntactic foams with low density (≤ 1.8g/cm3), reasonable mechanical strength (∼ 30 MPa) and very low thermal conductivity (≤ 1 W/m-K). In this manner, this process can be used for the low-cost and net-shape fabrication of closed-cell silicon carbide syntactic foams for high temperature applications.
Investigation of the phase state of transformation shear bands in superelastic Ni-rich NiTi shape memory alloys with synchrotron diffraction
Authors: Schmahl W. W. , Baruj A. , Khalil-Allafi J. , Nebel H. 
Published: April 2011

ABSTRACTThe deformation of superelastic NiTi due to the stress-induced transition from cubic B2 to monoclinic B19′ phase is localised in a Lüders-band-like transformation shear bands (TSB). We investigate the phase state and texture in the bands in-situ using diffraction with high-energy synchrotron-radiation. Residual austenite is observed to persist up to the end of the superelastic plateau in the stress-strain curve. The deformation corresponds to a displacement of the boundary of the TSB. After a certain volume of the specimen has transformed when the boundary has passed by, there is no further change of the crystallographic state of this volume up to the end of the macroscopic stress-strain plateau. The variant orientation texture is different at the surface from that present in the bulk.
Simulation of Absorbed Dose Distribution In Space Materials
Authors: Briskman Boris A. 
Published: April 2011

ABSTRACTThe problems of absorbed dose distribution simulation at on-ground space material tests are discussed. Several approaches to such simulation, oriented to increase the test adequacy and economy, are analyzed. Sometimes, it is possible to use quantitative criteria of absorbed dose distribution depending on the specific space vehicle orbit. The assessment of reliable simulation of the radiation spectrum may be made, for example, by introducing a special numerical characteristic of the depth dose profile in a material - depth dose criterion. For this purpose, it is recommended to use the ratio of the exponent index of the depth dose profile (μ) to the density of the material (ρ). In the simplest form, the depth dose profile can be represented as a sum of two exponents. The first depth dose profile applies to a near-the-surface layer of 5 to 10 μm in thickness, and the second to a layer of from 10 μm up to, as a minimum, 100 μm in thickness. The reference values of μ/ρ for typical spectra of ionizing radiation are calculated.
Total Dose Radiation Effects In Si Nanocrystal Non-Volatile Memory Transistors
Authors: Petkov Mihail P. , Douglas Bell L. , Walters Robert J. , Atwater Harry A. 
Published: April 2011

ABSTRACTWe report results pertinent to the high total dose tolerance of Si nanocrystal non-volatile memory cells. The nc-Si FETs made by ion implantation retained virtually unchanged write / erase characteristics, typical for the two-state devices, to cumulative doses exceeding 15 Mrad(Si).
Electron Spin Resonance Studies on Electron Beam Irradiated Carbon Nanotubes Dispersed in Styrene-Isoprene-Styrene Block Copolymer
Authors: Chipara Mircea , Beezhold Wendland , Webb Timothy , Zaleski Jeffrey M. , Stephenson Kristina , Dye David , Lau Kin-Tak 
Published: April 2011

ABSTRACTElectron spin resonance investigations on the effect of electron bombardment of nanocomposites obtained by dispersing carbon nanotubes within styrene-isoprene-styrene are reported. The experimental results revealed the absence of radiation-induced free radicals and a negligible effect of electron beam irradiation on the electron spin resonance spectra of carbon nanotubes.
FIB-Based Fatigue Testing of Silicon Nitride Thin Films for Space Applications
Authors: Chuang Wen-Hsien , Fettig Rainer K. , Ghodssi Reza 
Published: April 2011

ABSTRACTA novel micro-scale electrostatic actuator has been designed and fabricated to study fatigue properties of low-stress LPCVD silicon nitride thin films, which are the structural materials of microshutter arrays to be used in NASA's James Webb Space Telescope (JWST). To obtain different stress levels without high applied voltages, the electrostatic actuator was designed based on a resonant technique to achieve mechanical amplification. All fabricated devices were tested inside a focused-ion-beam (FIB) system with pressure of 10-6 torr at room temperature (23 ± 1 °C) and with the test duration ranging from 5 seconds to 8.5 hours, 105 to 109 cycles, respectively. From the experiment, no fatigue failure of low-stress LPCVD silicon nitride thin films has been observed up to 109 testing cycles, four orders of magnitude higher than the expected lifetime of the microshutter arrays. The presented test device and experimental technique can be extended to characterize fatigue properties for other thin film materials.
Beam Properties of the new Radiation Effects Research Stations at Indiana University Cyclotron Facility
Authors: von Przewoski B. , Rinckel T. , Manwaring W. , Ellis T. , Foster C. C. , Hall E. R. , Kinser T. , Murray K. M. 
Published: April 2011

ABSTRACTWe describe two new beamlines for radiation effects research at the Indiana University Cyclotron Facility. Protons with energies up to 205 MeV are available. One of the beamlines offers momentum selected beams at energies as low as 52 MeV.
Highly Stable Polymers based on Poly(m -carboranyl-siloxane) Elastomers
Authors: Swain Anthony.C. , Patel Mogon , Murphy Julian.J. 
Published: April 2011

ABSTRACTPoly(m-carboranyl-siloxane) elastomers containing a mixture of di-methyl- and methyl(phenyl)-silyl units were synthesised using the Ferric Chloride catalysed condensation reaction between di-chloro-di-organosilane and 1, 7-bis(di-methyl(methoxy)silyl)-m-carborane. These prepared polymers were aged either by heating in air at elevated temperature or by λ-irradiation from a 60Co source. Multinuclear (1H, 13C and 11B) solid and solution state nuclear magnetic resonance was used to evaluate degradation. λ-irradiation doses to 1 MGy were found to induce only a small reduction in elastomer properties as evidenced by a reduction in segmental chain dynamics. Ageing at temperatures below 350°C similarly displayed a small reduction in segmental chain dynamics together and a concomitant weight loss as measured by differential scanning calorimetry. Above 350°C degradation of the elastomer was dramatic with a decreased segmental chain dynamics and oxidation of the carborane cage, vide infra.
Piezoelectric PVDF Materials Performance and Operation Limits in Space Environments
Authors: Celina Mathew C. , Dargaville Tim R. , Chaplya Pavel M. , Clough Roger L. 
Published: April 2011

ABSTRACTPiezoelectric polymers based on polyvinylidene fluoride (PVDF) are of interest for large aperture space-based telescopes. Dimensional adjustments of adaptive polymer films are achieved via charge deposition and require a detailed understanding of the piezoelectric material responses which are expected to suffer due to strong vacuum UV, λ-, X-ray, energetic particles and atomic oxygen under low earth orbit exposure conditions. The degradation of PVDF and its copolymers under various stress environments has been investigated. Initial radiation aging studies using λ- and e-beam irradiation have shown complex material changes with significant crosslinking, lowered melting and Curie points (where observable), effects on crystallinity, but little influence on overall piezoelectric properties. Surprisingly, complex aging processes have also been observed in elevated temperature environments with annealing phenomena and cyclic stresses resulting in thermal depoling of domains. Overall materials performance appears to be governed by a combination of chemical and physical degradation processes. Molecular changes are primarily induced via radiative damage, and physical damage from temperature and AO exposure is evident as depoling and surface erosion. Major differences between individual copolymers have been observed providing feedback on material selection strategies.
Confocal X-ray Fluorescence (XRF) Microscopy: A New Technique for the Nondestructive Compositional Depth Profiling of Paintings
Authors: Woll Arthur R. , Bilderback Donald H. , Gruner Sol , Gao Ning , Huang Rong , Bisulca Christina , Mass Jennifer 
Published: April 2011

ABSTRACTA confocal x-ray fluorescence microscope was built at the Cornell High Energy Synchrotron Source (CHESS) to determine the composition of buried paint layers that range from 10–80 μm thick in paintings. The microscope consists of a borosilicate monocapillary optic to focus the incident beam and a borosilicate polycapillary lens to collect the fluorescent x-rays. The overlap of the two focal regions is several tens of microns in extent, and defines the active, or confocal, volume of the microscope. The capabilities of the technique were tested using acrylic paint films with distinct layers brushed onto glass slides and a twentieth century oil painting on canvas. The position and thickness of individual layers were extracted from their fluorescence profiles by fitting to a simple, semi-empirical model.
Solid-State NMR and Resonance Raman Studies of Ultramarine Pigments
Authors: Federico Eleonora Del , Schoefberger Wolfgang , Kumar Rajeev , Ling Wen , Kapetanaki Sofia M. , Schelvis Johannes , Jerschow Alexej 
Published: April 2011

ABSTRACTWe report on a study of ultramarine pigments via Colorimetry, resonance Raman, and 27Al, 29Si solid-state NMR spectroscopy. NMR parameters are shown to correlate well with the intensities of Raman signals corresponding to the chromophores S3−. and S2−.. Further, a correlation is established between the colorimetric parameters L* (lightness) and C* (chromaticity) and the paramagnetic shift in NMR spectra for both 27Al and 29Si. The parameter h (hue) appeared not to vary over the range of paramagnetic host concentrations studied. Preliminary results on faded pigments in both acidic and basic media show that the concentration of diamagnetic guest molecules in the sodalite lattice rises, and some of the paramagnetic species are replaced.
Protection Efficacy of Fluorinated Acrylic Copolymers Applied on Historical Italian Marbles.
Authors: Poli Tommaso , Toniolo Lucia 
Published: April 2011

ABSTRACTUse of polymeric materials to protect stone started in the 1960’s but the study and knowledge of the complex and multiple interactions between stone and polymers has been carried out only recently. In a previous paper [1] the problems related to the efficacy of a stone treatment (film formation, deep penetration and coating behavior) has been addressed. In this paper performance after a thermal and a simulated solar UV ageing has been evaluated. In particular the issues related to stability and durability of two fluorinated acrylic copolymers applied on two different Italian marbles, Carrara and S. Giuliano, have been investigated. The specimens characterized and treated with two new partially fluorinated acrylic copolymers, 2, 2, 2-trifluoroethyl methacrylate / methyl acrylate (TFEMA / MA) and trifluoromethyl-2, 2, 2-trifluorethyl methacrylate / methyl acrylate (HFIMA / MA), have been artificially aged in two different ways: with a long simulated solar UV ageing of 1000h and a thermal one at the same temperature (about 50°C) usually reached in the UV chamber, in order to separate the two ageing contributions (photochemical and thermal). After the ageing most of the testing methodologies suggested by UNI-Normal Italian protocol for evaluation of stone protective coatings, including capillary water absorption, static contact angles and colour variation, have been carried out. Slightly better protective efficacy was found for the HFIMA/MA before and after the two ageing. The important contribution of the thermal component in the worsening of the shielding efficacy has been assessed.
The role of Microstructure, Nanostructure and Composition in the Brilliant Red Slip of Roman Terra Sigillata Pottery from Southern Gaul
Authors: Sciau Philippe , Relaix Sabrina , Kihn Yolande , Roucau Christian 
Published: April 2011

ABSTRACTTerra sigillata ceramic is a fine ware produced during the Roman period. Its great success was due to its remarkable gloss, also called slip, which provides a bright deep red aspect. TEM-EELS and XRD techniques were used to understand the sub-microscopic origins of this singular aspect. Analysis investigations on five samples of two important Gaul workshops are described here. It appears that those samples have the same slip structure: sub-microscopic hematite and corundum crystals in a glass matrix. The matrix does not contain metallic ions, hematite is substituted in Al and Ti while corundum is substituted in Fe. The two crystal populations are homogeneously dispersed in the matrix and, together, give the specific red-orange colour to the sigillata.
The Analysis of Glazed Quartzite Sculpture from Kerma, Capital of Ancient Kush (Sudan)
Authors: Ellis Lisa , Newman Richard 
Published: April 2011

ABSTRACTScanning electron microscopy/energy-dispersive X-ray spectrometry (SEM/EDS) was used to characterize the composition of glazes found on a collection of blue glazed, white quartzite sculptures, excavated from 1913–1916 by the Harvard University–Boston Museum of Fine Arts Expedition at the site of Kerma, the capital of ancient Kush, in today's Sudan. The scientific analysis of these artifacts shows the experimental nature of this extremely rare manufacture which appears to have developed out of faience technology.