bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of processing conditions on rheological, thermal, and electrical properties of multiwall carbon nanotube/epoxy resin composites
Authors: Ivanov E. , Kotsilkova R. , Krusteva E. , Logakis E. , Kyritsis A. , Pissis P. , Silvestre C. , Duraccio D. , Pezzuto M. 
Published: January 2011

AbstractWe report on the effect of processing conditions on rheology, thermal and electrical properties of nanocomposites containing 0.02–0.3 wt % multiwall carbon nanotubes in an epoxy resin. The influence of the sonication, the surface functionalization during mixing, as well as the application of external magnetic field (EMF) throughout the curing process was examined. Rheological tests combined with optical microscopy visualization are proved as a very useful methodology to determine the optimal processing conditions for the preparation of the nanocomposites. The Raman spectra provide evidence for more pronounced effect on the functionalized with hardener compositions, particularly by curing upon application of EMF. Different chain morphology of CNTs is created depending of the preparation conditions, which induced different effects on the thermal and electrical properties of the nanocomposites. The thermal degradation peak is significantly shifted towards higher temperatures by increasing the nanotube content, this confirming that even the small amount of carbon nanotubes produces a strong barrier effect for the volatile products during the degradation. The ac conductivity measurements revealed lower values of the percolation threshold (pc) in the range of 0.03–0.05 wt %. CNTs for the nanocomposites produced by preliminary dispersing of nanotubes in the epoxy resin, compared to those prepared by preliminary functionalization of the nanotubes in the amine hardener. This is attributed to the higher viscosity and stronger interfacial interactions of the amine hardener/CNT dispersion which restricts the reorganization of the nanotubes. The application of the EMF does not influence the pc value but the dc conductivity values (σdc) of the nanocomposites increased at about one order of magnitude due to the development of the aforementioned chain structure. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Free volume changes on optical switching in azobenzene‐polymethylmethacrylate blends studied by a pulsed low‐energy positron beam
Authors: Harms Stephan , Rätzke Klaus , Pakula Christina , Zaporojtchenko Vladimir , Strunskus Thomas , Egger Werner , Sperr Peter , Faupel Franz 
Published: January 2011

AbstractPolymers including chromophores, which can be switched by light, have been studied extensively during the last years due to a host of potential applications which arise from the marked changes in physical properties on switching. Even though there is clear evidence that the free volume has a significant influence on the isomerization kinetics, the question of free volume changes on switching was only addressed recently. Using a pulsed low‐energy positron beam the ortho‐positronium lifetime τ3 was taken as a very sensitive free volume probe, and no change in free volume was detected on isomerization in an azobenzene‐polymethylmethacrylate (PMMA) copolymer containing about 8 wt % of the azobenzene moiety. Here, we report for the first time on free volume changes in an azobenzene‐PMMA blend with an azobenzene moiety concentration as high as 40 wt %. Using the same pulsed low‐energy positron beam, small but significant changes of τ3 were observed between the structurally relaxed dark and the UV‐illuminated states suggesting a decrease in free volume of the order of 10%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Urinary CD14 as a potential biomarker for benign prostatic hyperplasia – discovery by combining MALDI‐TOF‐based biostatistics and ESI‐MS/MS‐based stable‐isotope labeling
Authors: Cheng Hong‐Lin , Huang Hung‐Jen , Ou Bing‐Yuan , Chow Nan‐Haw , Chen Yen‐Wen , Tzai Tzong‐Shin , Wu Chin‐Jen , Chen Shu‐Hui 
Published: January 2011

AbstractPurpose: Quest for specific urinary biomarkers for benign prostatic hyperplasia (BPH).Experimental design: Proteomics studies were conducted with urines of the training set to discovering marker candidates that could differentiate BPH from normal subjects by matching results deduced from MALDI‐TOF of individual samples and results deduced from nanoLC‐ESI‐MS/MS‐based stable isotope dimethyl labeling of two pooled samples (BPH and normal). Samples were digested before analysis and such an approach takes into account the subject‐to‐subject variation and differential amount, as well as protein identification. Selected markers were validated by ELISA conducted on the training set and the test set as well as another set of urines collected from prostate cancer patients.Results: Nine marker candidates were identified from proteomics studies; CD14, prostate‐specific antigen and pancreatic α‐amylase precursor were further selected for ELISA validation. Urinary CD14 is among the best match with high specificity (>81%) for both training and test sets. In addition, from the study of prostate cancer patients, CD14 also allows the distinction of BPH from cancer with high specificity (84–100%) when combined with urinary prostate‐specific antigen.Conclusions and clinical relevance: Urinary CD14 is suggested to have a high specificity in the diagnosis of BPH in distinction from normal as well as cancer subjects.
Influence of tube diameter on carbon nanotube interconnect delay and power output
Authors: Rai Mayank Kumar , Sarkar Sankar 
Published: January 2011

AbstractThis paper address the influence of tube diameter on single walled carbon nanotube (CNT) bundle interconnect delay and power output in Very Large Scale application. We find that single‐walled carbon nanotube (SWCNT) bundle interconnects are of lower delay than copper interconnect due to low resistance and inductance. Power dissipation decreases with increase in tube diameter of the constituent SWCNT. CNT interconnect resistance and inductance increases with increase in tube diameter. On the other hand, with increase in tube diameter interconnect capacitance decreases. There is a trade off between delay and power dependence on tube diameter.
SR phase contrast imaging to address the evolution of defects during SiC growth
Authors: Argunova Tatiana S. , Gutkin Mikhail Yu. , Je Jung Ho , Mokhov Evgeniy N. , Nagalyuk Sergey S. , Hwu Yeukuang 
Published: January 2011

AbstractSliced SiC boule grown by physical vapor transport is investigated using synchrotron white beam phase contrast imaging combined with Bragg diffraction. The evolution of defects is revealed. In the early growth stage, foreign polytype inclusions not only induce massive generation of full‐core dislocations and dislocated micropipes but also attract them, forming slit‐type pores at the boundaries of inclusions.In the intermediate stage, when inclusions stop to grow and become overgrown by the matrix, the pore density significantly reduces, which is attributed to their transformation into new micropipes. In the later stage, the micropipe density decreases, providing evidence for their partial annihilation and healing. Mechanisms for the evolution from inclusions to pores and finally to micropipes during the crystal growth are further discussed.
Solution‐processed semitransparent p–n graphene oxide:CNT/ZnO heterojunction diodes for visible‐blind UV sensors
Authors: Cuong Tran Viet , Tien Huynh Ngoc , Luan Van Hoang , Pham Viet Hung , Chung Jin Suk , Yoo Dae Hwang , Hahn Sung Hong , Koo Kee‐Kahb , Kohl Paul A. , Hur Seung Hyun , Kim Eui Jung 
Published: January 2011

AbstractA high quality transparent p–n heterojunction device comprised of 1D zinc oxide (ZnO) nanorods (NRs) and an ultrathin 2D graphene oxide (GO):carbon nanotube (CNT) hybrid film was fabricated through a solution process. The turn on voltage and ideality factor of the device were 1.5 V and 6.1, respectively. Optical measurements revealed that the UV absorption of the ZnO NRs increased after a GO:CNT hybrid film was spray‐coated onto the NRs. As a result, the device exhibited a high response to UV illumination. The fabricated diode displayed high rectifying characteristics and excellent performance as a visible‐blind UV sensor.
Temperature‐dependent light‐output characteristics of GaInN light‐emitting diodes with different dislocation densities
Authors: Chhajed Sameer , Cho Jaehee , Schubert E. Fred , Kim Jong Kyu , Koleske Daniel D. , Crawford Mary H. 
Published: January 2011

AbstractWe have experimentally investigated the temperature dependence of optical‐output power of light‐emitting diodes (LEDs) with different threading dislocation densities (TDDs) to assess the influence of the TDD on the temperature stability of LEDs. Whereas the LED with high TDD shows a 64% decrease in optical‐output power when the ambient temperature increases from 20 to 150 °C, the LED with low TDD shows only a 54% decrease. The temperature dependence of the optical‐output power and current dependence of the characteristic temperature Tch of LEDs shows that short radiative recombination lifetime and low TDDs are essential to obtain LED characteristics that are tolerant of high temperatures.
Quantum coherence in photosynthetic complexes
Authors: Calhoun Tessa R. , Fleming Graham R. 
Published: January 2011

AbstractThe initial steps of photosynthesis require the absorption and subsequent transfer of energy through an intricate network of pigment–protein complexes. Held within the protein scaffold of these complexes, chromophore molecules are densely packed and fixed in specific geometries relative to one another resulting in Coulombic coupling. Excitation energy transfer through these systems can be accomplished with near unity quantum efficiency [Wraight and Clayton, Biochim. Biophys. Acta 333, 246 (1974)]. While replication of this feat is desirable for artificial photosynthesis, the mechanism by which nature achieves this efficiency is unknown. Recent experiments have revealed the presence of long‐lived quantum coherences in photosynthetic pigment–protein complexes spanning bacterial and plant species with a variety of functions and compositions. Its ubiquitous presence and wavelike energy transfer implicate quantum coherence as key to the high efficiency achieved by photosynthesis.
Time‐resolved spectroscopy of exciton‐related states in single crystals and single crystalline films of Lu3Al5O12 and Lu3Al5O12:Ce
Authors: Babin V. , Bichevin V. , Gorbenko V. , Kink M. , Makhov A. , Maksimov Yu. , Nikl M. , Stryganyuk G. , Zazubovich S. , Zorenko Yu. 
Published: January 2011

AbstractTime‐resolved excitation spectra were measured at the same conditions at 10 K in the 4–20 eV energy range for the luminescence of self‐trapped and various localized excitons as well as of Ce3+‐, Pb2+‐, and Bi3+‐related centers in single crystals and single crystalline films of Lu3Al5O12 garnet. The decay kinetics of the intrinsic 4.9 and 3.65 eV luminescence of Lu3Al5O12 crystals were studied at 4.2–300 K in the 10−9–10−3 s time range. The origin and structure of the exciton states as well as the luminescence, energy transfer, and recombination processes, taking place under excitation in the exciton absorption region, were discussed. The influence of various defects on the scintillation characteristics of Ce3+‐ and Pr3+‐doped Lu3Al5O12 crystals was considered.
Crystal orientation of GaN layers on (1010) m‐plane sapphire
Authors: Frentrup Martin , Ploch Simon , Pristovsek Markus , Kneissl Michael 
Published: January 2011

AbstractBased on the atomic arrangement of the $(10{\bar {1}}0)$ m‐plane sapphire surface, we have developed a model for the initial nucleation process of gallium‐nitride (GaN). This model describes why $(11{\bar {2}}2)$ and $(10{\bar {1}}{\bar {3}})$ are the preferred orientations of GaN on the $(10{\bar {1}}0)$ sapphire. The experimental results from high‐resolution X‐ray diffraction measurements, like the crystallographic relations and the twinning of the $(1{\bar {1}}0{\bar {3}})$ orientation are explained by the model too. Our model also predicts that $(11{\bar {2}}2)$ thin films are metal‐polar and $(1{\bar {1}}0{\bar {3}})$ thin films are nitrogen‐polar.
Stacking fault‐related luminescence features in semi‐polar GaN
Authors: Tischer Ingo , Feneberg Martin , Schirra Martin , Yacoub Hady , Sauer Rolf , Thonke Klaus , Wunderer Thomas , Scholz Ferdinand , Dieterle Levin , Müller Erich , Gerthsen Dagmar 
Published: January 2011

AbstractWe report about defect‐related emission bands in GaN. We establish a direct correlation between results from spatially and spectrally resolved cathodoluminescence bands at 3.32, 3.23, 3.20, 3.16, and 3.07 eV with findings obtained by transmission electron microscopy. The band around 3.32 eV was unambiguously assigned to I2 basal plane stacking faults (BSFs). The bands at 3.23, 3.20, 3.16, and 3.07 eV were detected in sample regions, where BSFs exist, but were not assigned to specific defect types, except for the 3.07 eV line which is a phonon replica of the transition at 3.16 eV.
Ni‐doped ZnO: Studies on structural and magnetic properties
Authors: Mohapatra J. , Mishra D. K. , Kamilla S. K. , Medicherla V. R. R. , Phase D. M. , Berma V. , Singh S. K. 
Published: January 2011

AbstractThe Zn1–xNixO (0 ≥ x ≥ 0.1) systems were synthesized by a solid‐state reaction technique at 700 °C for 7 h. The X‐ray diffraction (XRD) pattern reveals the presence of secondary peaks due to NiO in Ni overdoped (>0.03) ZnO matrix. The compositional mapping on 5% Ni‐doped ZnO on an electron probe microstructural analyzer (EPMA) indicates the segregation of oxides of Ni on the bulk surface. The ZnO samples doped with 3 and 5% Ni exhibit room‐temperature ferromagnetism (RTFM). But, 7 and 10% Ni‐doped ZnO samples do not exhibit ferromagnetism. Possibly, the enhanced antiferromagnetic interaction between neighboring Ni–Ni ions suppresses the ferromagnetic ordering, at higher doping concentrations of Ni, resulting in a rapid decrease in magnetic moments.
Effect of chirality and curvature of single‐walled carbon nanotubes on the adsorption of uracil
Authors: Rajarajeswari M. , Iyakutti K. , Kawazoe Y. 
Published: January 2011

AbstractAdsorption of uracil on single‐walled carbon nanotubes (SWCNTs) (5,2) and (5,5) in the presence of water molecules has been investigated using first‐principles technique. Uracil is adsorbed on the nanotube noncovalently through π–π stacking interaction. The binding strength of uracil varies with the chirality of the carbon nanotubes. Addition of water molecules inside and outside the nanotube altered the interaction of the uracil with the nanotube and modifies the binding strength. Orientation of the water molecule and the charge transfer through the CH bonds are the important factors in the interaction of the water molecule with the carbon nanotube.
Graphene allotropes
Authors: Enyashin Andrey N. , Ivanovskii Alexander L. 
Published: January 2011

AbstractUsing the density‐functional‐based tight‐binding method (DF‐TB) we performed a systematic comparative study of stability, structural, and electronic properties for 12 various types of graphene allotropes, which are likely candidates for engineering of novel graphene‐like materials.
Extra formation of positronium in amorphous polymers at low temperature
Authors: Laforest N. , Bas C. , De Baerdemaker J. , Djourelov N. , Dauwe C. 
Published: January 2011

AbstractPositron annihilation lifetime spectroscopy measurements of polystyrene and poly(methyl methacrylate) have been performed at 20 K during ∼400 h. An increase of the probability of positronium (Ps) formation with irradiation time is observed. This effect is due to the accumulation of shallow‐trapped electrons which are stable at low temperatures. Detailed analyses of the lifetime spectra within the blob model framework show that these electrons induced by the previous positron tracks act as extra blob electrons: they either recombine with a cation or form Ps. This kinetic analysis introduced by the blob model indicates that no formation of Ps occurs after the blob recombination in these amorphous polymers. An increase of the free positron lifetime with the measuring time is also observed. This effect can not be explained in terms of artifact of discrete analysis caused by the existence of an ortho‐positronium lifetime distribution.
Scanning thermal microscopy: A nanoprobe technique for studying the thermal properties of nanocomponents
Authors: Wielgoszewski Grzegorz , Sulecki Przemysław , Gotszalk Teodor , Janus Paweł , Grabiec Piotr , Hecker Michael , Ritz Yvonne , Zschech Ehrenfried 
Published: January 2011

AbstractIn this paper, a novel micromachined scanning thermal microscopy (SThM) microcantilever with a sharp, conductive platinum tip is proposed for temperature and thermal conductivity measurements in sub‐micron structures of micro‐ and nanoelectronic components. The idea and physical background of SThM operation is presented, together with brief description of probes and example images of a planar polycrystalline‐silicon microfuse obtained using passive‐ and active‐mode SThM.
Effect of electronic structure on single‐photon emission in InAs/InP quantum dot with quasi‐resonant excitation
Authors: Miyazawa T. , Takemoto K. , Nakaoka T. , Saito T. , Hirose S. , Sakuma Y. , Yokoyama N. , Arakawa Y. 
Published: January 2011

AbstractWe investigated the electronic structures of so‐called ‘double‐capped’ InAs/InP quantum dot suitable for a 1.55‐μm band single‐photon emitter. From a transmission‐electron‐microscope image of the quantum dots, we extracted accurate information of the size and shape. We calculated the electron and hole eigenenergies by applying an 8‐band k·p perturbation method into the quantum dot model based on the obtained size and shape. The calculated energies of the excitonic excited states agreed well with the resonant absorption peaks in a previously measured photoluminescence excitation spectrum with peaks that had been selected for quasi‐resonant excitation to improve single‐photon purity. This result suggests that the direct exciton creation into these states contributes to the suppression of excess carriers in the vicinity of the quantum dots, thus leading to a decrease in unwanted multiple‐photon emission probabilities. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Yield shear stress dependence on nanoindentation strain rate in bulk GaN crystal
Authors: Fujikane Masaki , Yokogawa Toshiya , Nagao Shijo , Nowak Roman 
Published: January 2011

AbstractThe strain rate controlled nanoindentation was performed in c‐plane (0001) and m‐plane (10–10) GaN crystals. The indentation velocity was ranged from 0.16 to 800 nm/s. The significant displacement bursts were detected after every perfect elastically deformations and they allowed us to calculate the maximum shear stress τmax. The τmax dependences on strain rate in two crystal orientations involved that the two perpendicular compressions induced the same plastic deformation mechanism. Comparing the obtained τmax with the Peierls potential and maximum shear stress in each slip system, {10–11} 〈11–20〉 dislocation nucleation may support the origin of the plastic deformation in GaN crystal. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of growth temperature of partial GaAs cap on InAs quantum dots in In‐flush process for single dot spectroscopy
Authors: Kumagai Naoto , Ohkouchi Shunsuke , Shirane Masayuki , Igarashi Yuichi , Nomura Masahiro , Ota Yasutomo , Yorozu Shinichi , Iwamoto Satoshi , Arakawa Yasuhiko 
Published: January 2011

AbstractWe have investigated effects of growth temperature of partial GaAs cap (Tcap) on InAs quantum dots (QDs) in indium‐flush (In‐flush) process with atomic force microscopy (AFM) and micro photoluminescence (μ‐PL) measurements. Tcap in In‐flush process are varied from 385 °C to 485 °C as an experimental parameter. In order to investigate the effects of Tcap on structural property of single InAs QD, shape of QD in initial capping process are characterized by AFM measurements in air at room temperature. While isotropic shape of QDs is kept in low Tcap conditions below about 440 °C, in‐plane anisotropy of initial shape of QDs are increased with increasing of Tcap due to elongation to the [1$ \bar 1 $0] direction. μ‐PL measurements are performed at 7K for the investigation of the effects of Tcap on optical property in single InAs QDs. In low Tcap conditions from 410 °C to 435 °C, distinct emissions from excitonic states in single QDs are observed. In the same Tcap range, the AFM result shows that isotropic shape of QDs is kept. On the other hand, in high Tcap conditions above about 440 °C, indefinite peaks and broad emissions appear remarkably. Excitonic emissions which are observed in low Tcap range are hardly observed in this high Tcap range (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polarization dependence of two‐photon absorption coefficient and nonlinear susceptibility tensor in InP
Authors: Matsusue Toshio , Bando Hiroyuki , Fujita Shoichi , Takayama Yusuke 
Published: January 2011

AbstractTwo‐photon absorption (TPA) effect in (001) InP is investigated using fs laser. Its dependences on wavelength and polarization are clarified by single and double beam methods with linearly polarized lights. Characteristic features are revealed and discussed with scaling law, crystal bonding and mutual relation of polarizations for double beams. The results are successfully analyzed on the basis of the third‐order susceptibility tensor for comprehensive understanding of TPA effect at any polarization geometry. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thin film bilayers of multiferroic bismuth ferrite on Pt–Si substrate
Authors: Wu Jiagang , Wang John , Xiao Dingquan , Zhu Jianguo 
Published: January 2011

AbstractA multiferroics/multiferroics BiFeO3/Bi0.90La0.10Fe0.90Zn0.10O3 (BFO/BLFZO) bilayer was deposited on Pt/TiO2/SiO2/Si substrates by radio frequency sputtering. The BLFZO layer strongly affects the phase purity, orientation growth, and leakage current of BFO layer. The bilayered capacitor exhibits a high dielectric permittivity of ∼162 and an improved magnetic behavior of 2Ms ∼ 34.6 emu/cm3, together with an excellent fatigue endurance. A remanent polarization of 2Pr ∼ 116.2 μC/cm2 for the bilayered capacitor is better than those of reported BFO bilayers. The impedance study indicates that lower freely mobile charges are responsible for the improved electrical behavior of the BFO/BLFZO bilayer. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectrum of infrasound radiation from supercell storms
Authors: Akhalkatsi M. , Gogoberidze G. 
Published: January 2011

AbstractWe consider the generation of acoustic waves by turbulent convection and perform spectral analysis of a monopole source of sound related to the heat production by condensation of moisture. A quantitative explanation of the correlation between intensity of infrasound generated by supercell storms and later tornado formation is given. It is shown that low lifting condensation level (LCL) and high values of convective available potential energy (CAPE), which are known to favour significant tornadoes, also lead to a strong enhancement of a supercell's low‐frequency acoustic radiation. Copyright © 2011 Royal Meteorological Society
Robust adaptive‐sliding mode tracking of state delayed nonlinear plants with actuator failures
Authors: Mirkin Boris , Gutman Per‐Olof , Shtessel Yuri 
Published: January 2011

AbstractIn this paper, we develop two sliding mode—model reference adaptive control (MRAC) schemes for a class of delayed nonlinear dynamic systems under actuator failure that are robust with respect to actuator failures, to an unknown plant delay, to a nonlinear perturbation, and to an external disturbance with unknown bounds. Appropriate Lyapunov–Krasovskii‐type functionals with ‘virtual’ adaptation gains are introduced to design the adaptation algorithms, and to prove stability. Two different controllers are designed: one with discontinuous and another with continuous control actions, respectively. Copyright © 2011 John Wiley & Sons, Ltd.