bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanostructured Arrays Formed by Finely Focused Ion Beams
Authors: Zuhr R. A. , Budai J. D. , Datskos P. G. , Meldrum A. , Thomas K. A. , Warmack R. J. , White C. W. , Feldman L. C. , Strobel M. , Heinig K. -H. 
Published: May 2017

AbstractAmorphous, polycrystalline, and single crystal nanometer dimension particles can be formed in a variety of substrates by ion implantation and subsequent annealing. Such composite colloidal materials exhibit unique optical properties that could be useful in optical devices, switches, and waveguides. However colloids formed by blanket implantation are not uniform in size due to the nonuniform density of the implant, resulting in diminution of the size dependent optical properties. The object of the present work is to form more uniform size particles arranged in a 2-dimensional lattice by using a finely focused ion beam to implant identical ion doses only into nanometer size regions located at each point of a rectangular lattice. Initial work is being done with a 30 keV Ga beam implanted into Si. Results of particle formation as a function of implant conditions as analyzed by Rutherford backscattering, x-ray analysis, atomic force microscopy, and both scanning and transmission electron microscopy will be presented and discussed.
In Situ Studies of the Vibrational and Electronic Properties of Si Nanoparticles
Authors: Fox J. R. , Akimov I. A. , Xi X. X. , Sirenko A. A. 
Published: May 2017

AbstractWe report on in situ studies of the vibrational properties of ultra-thin Si layers grown by dc magnetron sputtering in ultrahigh vacuum on amorphous MgO and Ag buffer layers. The average thickness of the Si layers ranged from monolayer coverage up to 200 Å. The interference enhanced Raman scattering technique has been used to study changes in the phonon spectra of Si nanoparticles during the crystallization process. Marked size-dependencies in the phonon density of states of the Si quantum dots and the relaxation of the k-vector conservation condition with decrease in size of the Si nanoparticles have been detected. Electron energy loss spectra have been collected for amorphous and crystallized Si nanoparticles on SiO2 buffer layers and the difference in the onset of the electronic transitions have been found.
X-ray Reflectivity Study of Porous Silicon Formation
Authors: Chamard V. , Dolino G. , Eymery J. 
Published: May 2017

AbstractX-ray reflectometry is used to study the first stages of formation of thin n-type porous silicon layers. Results on classical n−-type porous silicon prepared under illumination are first reported. Then, the effect of the illumination during the formation is observed by comparing n+/− - type samples prepared in darkness or under illumination. X-ray specular reflectivity measurements allow to observe an increase of the surface porosity even for the short formation times and a macroporous layer under the nanoporous layer is also identified for illuminated samples. The presence of a crater at the top of the layer is observed by profilometer measurements, especially in the case of illuminated samples. Specular and diffuse x-ray scattering results show important effects of light during the porous silicon formation.
Thermodynamics and Kinetics of Melting and Growth of Crystalline Silicon Clusters
Authors: Keblinski P. 
Published: May 2017

AbstractMolecular-dynamics (MD) simulations and the Stillinger-Weber three-body potential are used to study the growth and stability of silicon clusters of diameters from 2 to 5 nm embedded in the melt. Our simulations show that the melting temperature of such nano-clusters is lower than the bulk melting temperature by an amount proportional to the inverse of the cluster size. We also show that the nature of the kinetics of such small Si clusters is essentially the same as that of the homoepitaxial growth. In particular, we show that the mobility of the highly-curved crystalliquid interface is controlled by diffusion in the adjacent melt, and is characterized by the same activation energy.
Germanium Nanostructures Fabricated by PLD
Authors: Hassan K. M. , Sharma A. K. , Narayan J. , Muth J. F. , Teng C. W. 
Published: May 2017

AbstractQuantum confined nanostructures of semiconductors such as Ge and Si are being actively studied due to their interesting optical and electronic transport properties. We fabricated Ge nanostructures buried in the matrix of polycrystalline-AIN grown on Si(111) by pulsed laser deposition at lower substrate temperatures than that used in previous studies. The characterization of these structures was performed using high resolution transmission electron microscopy (HRTEM), photoluminescence and Raman spectroscopy. HRTEM observations show that the Ge islands are single crystal with a pyramidal shape. The average size of Ge islands was determined to be 15 nm, considerably smaller than that produced by other techniques. The Raman spectrum reveals a peak downward shift, upto 295 cm−1, of the Ge-Ge mode caused by quantum confinement in the Ge-dots. Photoluminescence (PL) was observed both with a single layer of Ge nanodots embedded in the AlN matrix and from ten layers of dots interspersed with AIN. The PL of the dots was blue shifted by ˜0.266 eV from the bulk Ge value of 0.73 eV at 77 K, resulting in a distinct peak at ˜1.0 eV. The full width at half maximum (FWHM) of the peak was 13 meV, for the single layer and 8 meV for the ten layered sample, indicating that the Ge nanodots are fairly uniform in size, which was found to be consistent with our HRTEM results. The importance of pulsed laser deposition (PLD) in fabricating novel nanostructures is discussed.
Novel Route for the Preparation of CuSe and CuInSe2 Nanoparticles
Authors: Malik M. Azad , O'brien Paul , Revaprasadu N. , Wakefield G. 
Published: May 2017

AbstractGood quality, close to mono-dispersed, nanoparticles of CuSe and CuInSe2 have been prepared from thermolysis reactions in tri-n-octylphosphine oxide (TOPO). Bis(diethyldiselenocarbamato)-copper(II) ([Cu(Se2CNEt2] )2») was used to prepare CuSe and TOPSe, CuCI and InCl3 were reacted to form CuInSe2. HRTEM images showed that the particles have reasonable monodispersity and are crystalline. Clear lattice fringes were observed in single dots of CuInSe2 (ca. 4 nm) and CuSe (ca. 16 nm). The particles are capped with TOPO and the SAED pattern showed cubic CuInSe2 and hexagonal CuSe.
The Preparation and Characterization of Nanocrystalline Indium Tin Oxide Films
Authors: Aikens J. , Sarkas H. W. , Brotzman R. W. 
Published: May 2017

AbstractNanocrystalline indium tin oxide (ITO) powder is prepared by gas phase condensation (GPC) and used to produce conductive optical coatings. Materials produced by GPC are commercially available at reasonable cost and bridge the gap between basic science and product development. Nanocrystalline ITO films are transparent (>95%), conductive, and offer distinct device processing advantages. The oxidation state and surface chemistry of ITO may be tailored for particular applications and offers a flexible, affordable alternative to competitive films. The preparation and characterization of nanocrystalline ITO films and device applications will be discussed.
Defects and Phonon Assisted Optical Transitions in Si Nanocrystals
Authors: Allan G , Delerue C , Lannoo M 
Published: May 2017

AbstractPhonon-assisted and zero-phonon radiative transitions in nanoscale silicon quantum dots are studied using a new approach which combines a full calculation of the confined electronic eigenstates and vibration modes. We predict that the confinement, combined with the indirect bandgap of bulk silicon, must have several important consequences on the luminescence of a single silicon dot: i) a large broadening of the peaks, in the range of 10s of meV for a 3 nm dot, in spite of the atomic-like electronic structure of the dot ii) a great sensitivity of the spectrum to the size and the shape of the dot. We obtain that phonon-assisted transitions always dominate, even for size below 2 nm. Finally, we show that the radiative recombination in presence of an oxygen related surface defect (Si=O) is also assisted by optical phonons.
Nanoparticle-Based Contacts to CdTe
Authors: Schulz D. L. , Ribelin R. , Curtis C. J. , King D. E. , Ginley D. S. 
Published: May 2017

AbstractOur team has been investigating the use of particle-based contacts in CdTe solar cell technologies. Toward this end, particles of Cu-doped HgTe (Hg-Cu-Te) and Sb-Te have been applied as contacts to CdTe/CdS/SnO2heterostructures. These metal telluride materials were characterized by standard methods. Hg-Cu-Te particles in graphite electrodag contacts produced CdTe solar cells with efficiencies above 12% and series resistance (Rse) of 6 Ω or less. Metathesis preparation of Cu(I) and Cu(II) tellurides (i.e., Cu2Te and CuTe, respectively) were attempted as a means of characterizing the valence state of Cu in the Hg-Cu-Te ink. For Sb-Te contacts to CdTe, open circuit voltages (Vocs) in excess of 800 mV were observed, however, efficiencies were limited to 9%; perhaps a consequence of the marked increase in the Rse(i.e., >20 Ω) in these non-graphite containing contacts. Acetylene black was mixed into the methanolic Sb-Te colloid as a means of reducing Rse, however, no improvement in device properties was observed.
Luminescence Study of Self-Assembled, Silicon Quantum Dots
Authors: Miyazaki S. , Shiba K. , Miyoshi N. , Etoh K. , Kohno A. , Hirose M. 
Published: May 2017

AbstractHemispherical silicon quantum dots (QDs) have been self-assembled with an areal density as high as ~2−1011 cm−2 on SiO2/Si(100) and quartz substrates by controlling the early states of low pressure chemical vapor deposition (LPCVD) of pure silane. It is found that, for the thermally-oxidized Si QDs, when the mean Si dot height is decreased from 6.3 nm to 1~2 nm, the photoluminescence (PL) peak energy is increased from 1.2 to 1.4 eV at room temperature while the optical absorption edge determined by photothermal deflection spectroscopy is shifted from 1.9 to 2.5 eV. In addition to the observed Stokes shift as large as 0.7−1.1 eV, a weak temperature dependence of the broad luminescence band and non-exponential luminescence decay with a mean life time of sub-msec even at room temperature suggest that localized, radiative recombination centers existing presumably in the SiO2/Si dot interface are responsible for the efficient PL from the Si QDs. From the change in room temperature PL by SiO2 thinning and removal in a dilute HF solution, it is demonstrated that the surface passivation of Si QDs plays an important role for the efficient light emission at room temperature.
Evaporated Polycrystalline Germanium for Near Infrared Photodetection
Authors: Colace L. , Masini G. , Galluzzi F. , Assanto G. 
Published: May 2017

AbstractWe present low cost near infrared photodetectors based on polycrystalline Ge film thermally evaporated on a silicon substrate. We demonstrate that, by proper choice of deposition conditions and device configuration, a responsivity of 16mA/W and a response time of a few nanoseconds can be achieved at the wavelength of 1.3micron. The device can operate up to 1.55micron. We also describe the fabrication and the operation of a 16 pixel linear detector array, with pitch of about 100 micron.
Dechannealing Study of Nanocrystalline Si:H Layers Produced by High Dose Hydrogen Irradiation of Silicon Crystals
Authors: Popov V. P. , Gutakovsky A. K. , Antonova I. V. , Zhuravlev K. S. , Spesivtsev E. V. , Morosov I. I. , Pokhil G. P. 
Published: May 2017

AbstractA study of Si:H layers formed by high dose hydrogen implantation (up to 3x107cm-2) using pulsed beams with mean currents up 40 mA/cm2 was carried out in the present work. The Rutherford backscattering spectrometry (RBS), channeling of He ions, and transmission electron microscopy (TEM) were used to study the implanted silicon, and to identify the structural defects (a-Si islands and nanocrystallites). Implantation regimes used in this work lead to creation of the layers, which contain hydrogen concentrations higher than 15 at.% as well as the high defect concentrations. As a result, the nano- and microcavities that are created in the silicon fill with hydrogen. Annealing of this silicon removes the radiation defects and leads to a nanocrystalline structure of implanted layer. A strong energy dependence of dechanneling, connected with formation of quasi nanocrystallites, which have mutual small angle disorientation (<1.50), was found after moderate annealing in the range 200-500°C. The nanocrystalline regions are in the range of 2-4 nm were estimated on the basis of the suggested dechanneling model and transmission electron microscopy (TEM) measurements. Correlation between spectroscopic ellipsometry, visible photoluminescence, and sizes of nanocrystallites in hydrogenated nc-Si:H is observed.
Formation Process of Si Nanoparticles Formed by Laser Ablation Method
Authors: Makimura T. , Mizuta T. , Ueda T. , Murakami K. 
Published: May 2017

AbstractUtilizing laser ablation of Si targets, nanoparticles can be cleanly formed in rare gas. In order to fabricate nanoparticles with well-defined structures such as those whose surfaces are chemically modified, it is important to investigate the formation process of the nanoparticles. We have developed a decomposition method for measuring time-resolved spatial distributions of nanoparticles in rare gas. Applying this method, we have investigated formation processes of silicon nanoparticles in 2-Torr argon gas. The nanoparticles are found to grow from 300 Ais to 1 ms after the ablation.
Characterization of Laser Ablated Germanium Nanoclusters
Authors: Vijayalakshmi S. , Shen F. , Zhang Y. , George M. A. , Grebel H. 
Published: May 2017

AbstractMorphological characterization and the nonlinear optical properties of laser ablated germanium nanoclusters are discussed in this paper. Laser ablated films contain micron sized droplets that are composed of nanoclusters. The clusters have cubic and tetragonal symmetry. Results from TEM, AFM, and XRD are presented for the surface characterization. Nonlinear absorption is observed at very low light intensities and nonlinear absorption and refraction are seen at peak light intensities of 18 KW/cm2 at λ. = 532 nm. The estimated change in refractive index is 0.05 at these intensity levels.
Development of a Porous Silicon Based Biosensor
Authors: Dancil Keiki-Pua S. , Greiner Douglas P. , Sailor Michael J. 
Published: May 2017

AbstractIn this paper we demonstrate that porous silicon (PS) can be used as an immobilization matrix and a transducer for biosensor applications. Thin layers of PS were fabricated showing fine structure in their reflection spectra, characteristic of longitudinal optical cavity modes, or Fabry-Perot interference fringes. The PS surface was modified by covalently bonding streptavidin to a heterobifunctional linker immobilized to the surface using common silane chemistry. The mode spacing and wavelength in the interference spectrum was modified, by displacing buffer and introducing proteins into the PS layer. Protein-protein interactions between immobilized Streptavidin and biotinylated Protein A followed by Protein A and IgG were detected. The surface was regenerated during the course of the experiment showing reversibility of the sensor at the third layer.
Heavy Metal Contain Cu and Cd on the Mullet in the estuary of Donan River, Cilacap, Central Java
Authors: Prastyo Yudha , Batu Djamar T.F Lumban , Sulistiono Sulistiono 
Published: May 2017

The estuary of Donan River is an aquatic area that commonly utilized for some activities such as industrial, fisheries and domestic activities. The effluents of many activities may be cause heavy metal contamination for water enivornemant and organism live in the water. The aim of this research was to analyse heavy metal contain Cu and Cd on the mullet (Chelon subviridis) muscle caught at estuary of Donan River, and to determine the safety limit for community consumption. Sampling had been carried out for 6 months, from August 2015 to January 2016. Heavy metal concentration was measured by AAS (Atomic Absorption Spectrophotometer). Result of the study shows that heavy metal Cu and Cd in the fish muscle were 0.5009-2.6021 mg/kg and 0.0165-0.2307 mg/kg, respectively that were higher than safety limit. Based on the study, the safety limit for consumption is 151.72 g meat/week (for adult 50 kg body weight) and 45.52<br />g meat/week (for child 15 kg body weight).
Imunomodulator Activity of Alginate Oligosaccharides from Alginate Sargassum crassifolium
Authors: Subaryono Subaryono , Perangiangin Rosmawati , Suhartono Maggy Thenawidjaja , Zakaria Fransiska Rungkat 
Published: May 2017

Alginate oligosaccharides (AOS) are oligosaccharides produced from depolimerization of the alginate polymer, and is reported to have various biological activities. The study aims is to determine the effect of AOS<br />production conditions and their effects on products and its activities as an immunomodulatory compound. Production of alginate oligosaccharides (AOS) enzymatically carried out with the help of alginate lyase enzyme produced from the bacterium Bacillus megaterium S245. Variation of incubation time is 2, 4, 6 and 8 hours at concentrations of alginate lyase enzyme addition of 25, 50, 75 and 100U. Treatment of enzyme concentration and the duration of incubation in the production of AOS produces a degree of polymerization (DP) 2-7. In vitro activity test showed AOS is have ability to induce cell proliferation of human lymphocytes.<br />This type of cell lymphocytes proliferation induced by AOS is a CD 8 cells or cytotoxic T cell and non cell CD4 / CD8. AOS production conditions with the addition of alginate lyase enzyme 50 U and incubation period 2 hours has produce AOS with the highest index of lymphocyte proliferation 117.6+3.6% or an increase of 43.24% compared to the native alginat polymer.<br /><br /><br />
Production of Alginate Oligosaccharides (AOS) as Prebiotic Ingredients through by Alginate lyase enzyme
Authors: Afni Fahriza Sri , Purwaningsih Sri , Nurilmala Mala , Peranginangin Rosmawati 
Published: May 2017

Prebiotics is indigestible foods that can not be digested but can stimulate the growth and activity of bacteria in the digestive tract effecting human health. Alginate oligosaccharides (AOS) can be used as a source of prebiotic. That compounds can be produced enzymatically by cutting long chain alginates using alginate lyase. The aim of this study was to produce alginate lyase enzyme then producing Alginate oligosaccharides (AOS) as a prebiotic ingredients. The alginate lyase enzyme can be produced from Bacillus megaterium bacteria using a discontinuous fermentor. The enzyme was optimum temperature of 45°C and an optimum pH of 7.0. Alginate oligosaccharides production was performed with the addition of different enzyme concentrations 25, 50, 75, and 100 U. The result of the addition of enzyme (25, 50,75 U) showed that the value of polymerization degrees (DP) were between 4-5. However, the addition of enzyme (100 U) was in the range of DP 3-4. Bacterial probiotic growth test results of Bifidobacteria and Lactobacillus showed that 1% added AOS media were able to increase the growth of probiotic bacteria compared to the<br />media without addition of AOS. The addition Alginate lyase activity of 50 U in AOS production is the best treatment of both probiotic bacteria. <br /><br />
Purification of Sardine Fish Oil Through Degumming and Neutralization
Authors: Bija Stephanie , Suseno Sugeng Heri , Uju Uju 
Published: May 2017

The quality of sardine fish oil can be improved by purification method through the step of degumming and neutralization. The aimed of this this study was analysis characteristic of crude sardin fish oil and determined the best method of purification. Degumming was carried out using 30% water and salt at concentration 5%, 8%, 10% b/v. Neutralization process using NaOH with 16°Be and bleaching using 5% Magnesol XL. All step of refining was done at 50°C, 60°C, 70°C, and 80°C. The result of analysis showed that sardine crude fish oil had 24.86% of palmitic acid as the highest fatty acid, heavy metal was not detected,<br />dencity was 0.92 g/cm3 and viscocity was 51 cPs. The best treatment of purification method was degumming using 5% NaCl at 50°C with rendement 65.37±0.72%; free fatty acid (FFA) 0.38±0.03%; peroxide (PV) 1.07±0.12 mEq/kg; anisidine (p-AnV) 15.18±0.16 mEq/kg; total oxidation value (TOTOX) 17.31±0.39 mEq/kg; and clarity was 75.09± 1.20%.<br /><br />
INTERVENÇÃO CIRURGICA TARDIA EM PSEUDOARTROSE DIAFISÁRIA DE FÊMUR: RELATO DE CASO
Authors: Silva Anna Victoria Souza , Brusaca Luiz Augusto , Rolim Cabral Kim Theodoro Da Silva , Sbruzzi Ivanete Chaves , De Andrade Gislaine Priscila , Da Silva Vitor Alexandre 
Published: June 2017

Resumo - O excesso de veículos circulantes tem como consequência o aumento de acidentes automobilísticos. Desta forma, este índice se tornou uma preocupação, devido ao tempo de reabilitação e reinserção social do indivíduo. É comum em acidentes ocorrerem casos de fratura, de forma que nem sempre, a consolidação acontece de maneira adequada. Com isso, em toda falha na fusão óssea, a etiologia pode apresentar diversos fatores como causa, de uma patologia denominada como Pseudoartrose. O presente estudo tem como objetivo relatar um caso desta doença: paciente do sexo masculino, 23 anos, com a aquisição de politraumatismo, ocasionando fratura diafisária em terço distal de fêmur direito. Como intervenção, foi submetido a tratamento cirúrgico tardio e implantação de placa de compressão. Após o ato cirúrgico foi observada a não consolidação óssea devido à ausência de repouso do paciente no pós-operatório, apresentando então um prognóstico desfavorável, havendo a necessidade de troca da osteossíntese. A nova abordagem escolhida para o caso foi a implantação de osteossíntese com estabilidade absoluta, mais conhecida como Illizarov. Palavras-chave: Pseudoartrose; Fraturas do Fêmur; Ferimentos; Lesões. Área do Conhecimento: Fisioterapia