bluuebunny/crossref_metadata_2025_split huggingface dataset:
Controlling the correlations in frequency upconversion in PPLN and PPKTP waveguides
Authors: Brecht Benjamin , Eckstein Andreas , Silberhorn Christine 
Published: February 2011

AbstractFrequency upconversion can be utilized as flexible broadband mode selector for engineered phase matching properties. We give a detailed spectral analysis of frequency upconversion in two different nonlinear waveguides, namely LiNbO3 and KTiOPO4.We investigate the spectral correlations between input and output photon and derive conditions for their absence. By applying our analysis to the special scenario of upconverting a 1550 nm input photon, we find that for this scenario LiNbO3 is better suited than KTiOPO4. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Realistic g(2) measurement of a PDC source with single photon detectors in the presence of background
Authors: Eckstein Andreas , Christ Andreas , Mosley Peter J. , Silberhorn Christine 
Published: February 2011

AbstractThe g(2) correlation function of a light beam depends on its photon statistcs. In quantum optics, this effect can be used to determine the effective mode number of a type II parametric downconversion source.However, the outcome is very sensitive against background light from other sources. We consider the experimental challenges of this approach and introduce a simple model to account for influence of the background. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hot carrier cooling by acoustic phonons in epitaxial graphene by ultrafast pump‐probe spectroscopy
Authors: Sun Dong , Divin Charles , Berger Claire , de Heer Walt A. , First Phillip N. , Norris Theodore B. 
Published: February 2011

AbstractWe report the application nondegenerate ultrafast mid‐infrared spectroscopy to investigate the acoustic phonon cooling process in epitaxial graphene. We show that the power‐dependent experimental results match theoretical predictions of the low temperature acoustic cooling process. The hot phonon effect in acoustic phonon cooling is observed experimentally, and a deformation potential of 30 eV can be determined from fitting the data. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Si and SixGe1‐x NWs studied by Raman spectroscopy
Authors: Anaya J. , Prieto A. C. , Martínez O. , Torres A. , Martín‐Martín A. , Jiménez J. , Rodríguez A. , Sangrador J. , Rodríguez T. 
Published: February 2011

AbstractGroup IV nanostructures have attracted a great deal of attention because of their potential applications in optoelectronics and nanodevices. Raman spectroscopy has been extensively used to characterize nanostructures since it provides non destructive information about their size, by the adequate modeling of the phonon confinement effect. The Raman spectrum is also sensitive to other factors, as stress and temperature, which can mix with the size effects borrowing the interpretation of the Raman spectrum. We present herein an analysis of the Raman spectra obtained for Si and SiGe nanowires; the influence of the excitation conditions and the heat dissipation media are discussed in order to optimize the experimental conditions for reliable spectra acquisition and interpretation. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Correlation between cathodoluminescent and electrical properties of dislocation network in the space charge region of Schottky‐diode
Authors: Bondarenko Anton , Vyvenko Oleg , Isakov Ivan , Kononchuk Oleg 
Published: February 2011

AbstractA detailed investigation and comparison of low‐temperature cathodoluminescent (CL) and electrical properties of DN is presented. The correlations between the CL, electron beam induced current (EBIC), and CV measurements using the DC electric bias as a parameter are established and analyzed in the scope of the calculated theoretical model. A new CL measurement technique that is complimentary to conventional space charge region spectroscopy (SCRS) methods such as DLTS and MCTS is proposed and the first experimental results using this new approach are described. Shallow dislocation‐related level Ev+Et=0.1 eV is shown to be responsible for D1 dislocation‐related luminescence line. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of silicon ribbon by the SEM methods
Authors: Brantov Sergey , Feklisova Olga , Yakimov Eugene 
Published: February 2011

AbstractInvestigation of silicon layers grown on carbon foil was carried out using the Electron Backscatter Diffraction (EBSD) and Electron Beam Induced Current (EBIC) methods. The EBSD investigations showed that the surface of silicon ribbon is close to (110) and that most of grain boundaries (GBs) are twin boundaries with the misorientation angle of 60° between the neighbouring grains. The diffusion length in Si ribbon studied was obtained to exceed 35 μm. The EBIC measurements showed that the recombination contrast of dislocations and twin GBs at room temperature is practically absent and only random GBs produced a noticeable contrast. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dispersion of photoluminescence peak positions in asymmetric InAs QD multi quantum well structures
Authors: Casas Espínola J. L. , Torchynska T. V. , Polupan G. , Martínez M. Ojeda 
Published: February 2011

AbstractThe photoluminescence and its temperature dependences have been investigated for InAs quantum dots (QDs) embedded in asymmetric GaAs/InxGa1‐xAs/In0.15Ga0.85As/GaAs quantum wells (DWELL structures) as a function of the In content x (x=0.10‐0.25) in the capping InxGa1‐xAs layer. Photoluminescence (PL) study reveals the red shift of QD ground state peak when x increases from 0.10 to 0.15. The significant degradation of PL intensity is monitored together with a blue shift of PL peaks and PL band broadening when x = 0.20 or 0.25. The fitting procedure has been applied on the base of Varshni analysis to PL peaks. It is shown that all DWELL structures are characterized by the same Varshni parameters that are close, but not equal, to the band gap shrinks with temperature in the bulk InAs. The last fact testifies that in studied DWELL structures the process of In/Ga intermixture between QDs and a capping layer takes place partially. However this process cannot explain the difference in PL peak positions. This difference, apparently, related to the different levels of elastic strain in DWELLs that change non monotonically due to the variation of In concentrations in capping layers. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elastic stress and emission nonhomogeneity in asymmetric InAs quantum dot in a well structures
Authors: Casas Espínola José L. , Torchynska Tetyana V. , Palacios Gomez Jesús , Gómez Gasga G. , Vivas Hernández Alejandro , Cisneros Tamayo Ricardo 
Published: February 2011

AbstractPhotoluminescence (PL) and X‐ray diffraction (XRD) have been studied in InAs quantum dots (QDs) embedded in asymmetric GaAs/InxGa1‐xAs/In0.15Ga1‐0.15As/GaAs quantum wells (dot‐in‐a‐well, DWELL) with the parameter x=0.10‐0.25. The parameter x increasing in the capping layer is accompanied by the non monotonous variation of InAs QD parameters. The PL intensity increases and the PL peak shifts to low energy in structures with x=0.15. On the contrary the structures with x=0.20 and 0.25 are characterized by lower PL intensities and PL peak positions shifted to higher energy. The method of X‐ray diffraction has been applied with the aim to study the variation of elastic strain in asymmetric DWELL structures. It was shown that the minimum of elastic strain corresponds to DWELL with x=0.15. In DWELLs with x=0.20 and 0.25 the level of compressive strain increases. The reasons of strain variation are discussed as well. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nucleation in the Karlsruhe plume during the COPS/TRACKS‐Lagrange experiment
Authors: Junkermann W. , Hagemann R. , Vogel B. 
Published: February 2011

AbstractA plume of ultrafine particles was observed downwind of the Karlsruhe city and industrial area during the COPS/TRACKS Lagrangian airborne experiment in summer 2007. These ultrafine particles were identified as nucleation‐generated aerosols from emissions of a coal‐fired power plant and an adjacent refinery, the two main emitters of sulphur dioxide in the area. Modelling the production and growth of aerosols with the COSMO‐ART model required, in agreement with the known emission sources, a strong elevated source of sulphur dioxide to explain the temporal evolution of the particle plume. The power plant at Karlsruhe Rheinhafen emits from a 233 m high chimney. The ultrafine particles produced from these fossil‐fuel‐related sources were the dominant fraction of all ultrafine particles in the rural area of the Kraichgau downwind of Karlsruhe, exceeding all other anthropogenic sources and are suspected of being the major contribution to the number of cloud condensation nuclei (CCN) on a regional scale. Compared to previous investigations on the sulphur chemistry in power‐plant plumes, emissions from this power plant, which is equipped with modern stack‐gas cleaning technology, had a higher yield of nucleation‐mode aerosols as CCN precursors per emitted sulphur dioxide mass. Copyright © 2011 Royal Meteorological Society
Influence of the wind profile on the initiation of convection in mountainous terrain
Authors: Hagen Martin , van Baelen Joël , Richard Evelyne 
Published: February 2011

AbstractA number of days with small precipitating convective cells were investigated using weather radars during the COPS (Convective and Orographically‐induced Precipitation Study) field campaign in the region of the Vosges and the Rhine Valley in Central Europe. Depending on the weather situation, two distinct mechanisms could be identified for the initiation of convection. On some days, cells were initiated over the ridge of the Vosges, whereas on other days cells were initiated in the lee of the Vosges. The initiation of convection appeared to be concentrated in a few favourable locations. Using the Froude number, it was possible to describe the two distinct mechanisms. When the Froude number was low, the flow was diverted around the Vosges and thermally driven convergence at the ridge initiated convection, whereas when the Froude number was high, the flow passed through mountain gaps and then converged on the lee side with the flow in the Rhine Valley. The convergence on the lee side was enhanced at locations where the outflows through valleys converged. Low Froude numbers were accompanied by weak winds varying with height, whereas high Froude numbers were observed during situations with stronger southwesterly winds increasing with height. Copyright © 2011 Royal Meteorological Society
On the relationship between water vapour field evolution and the life cycle of precipitation systems
Authors: Van Baelen J. , Reverdy M. , Tridon F. , Labbouz L. , Dick G. , Bender M. , Hagen M. 
Published: February 2011

AbstractIn this work, we investigate the relationship between the structure and evolution (from initiation to decay) of precipitation systems, and the associated water vapour distributions during the COPS (Convective Orographically‐induced Precipitation Study). This international field campaign took place over an area from the Vosges to the Black Forest Mountains, across the Rhine Valley, in summer 2007. In particular, we consider water vapour retrieval through GPS integrated water vapour 2D maps and 3D tomography, and compare these to precipitation systems observed with the ground‐based C‐band POLDIRAD weather radar.We have demonstrated the predominant role of water vapour as a precursor to convective initiation for local convective cell generation. Water vapour accumulation on the crest of the orography is associated with ridge convection, while water vapour passing over the mountain top and creating valley outflows generates lee‐side convection, often triggered by a small hill positioned within or close to the valley exit, or by a local convergence with the water vapour field over the plain.We have also noted that frontal systems seem to develop preferentially where the largest amount of water vapour is available. Likewise, in the case of frontal systems, well‐formed synoptic‐scale storms are associated with high water vapour signatures, while weaker systems with embedded convection appear to trail high water vapour areas where the convective element is associated with local water vapour depletion. This latter aspect could be the signature of convective cloud formation, when water vapour is transferred into liquid water, before the onset of precipitation. Copyright © 2011 Royal Meteorological Society
Characterization of metabolism of (+)‐praeruptorin B and (+)‐praeruptorin E in human and rat liver microsomes by liquid chromatography coupled with ion trap mass spectrometry and time‐of‐flight mass spectrometry
Authors: Song Yue‐Lin , Yan Ru , Jing Wang‐Hui , Zhao Hai‐Yu , Wang Yi‐Tao 
Published: February 2011

AbstractPeucedani Radix is a Chinese medicinal herb noted for its effects on treatments of respiratory and pulmonary disorders. As a part of a systematic pharmacokinetic evaluation of the herb in our laboratory, the present study investigated, for the first time, the metabolic profile of (+)‐praeruptorin B (dPB) and (+)‐praeruptorin E (dPE), two main bioactive constituents of Peucedani Radix in pooled liver microsomes of rats (RLMs) and humans (HLMs). dPE was eliminated faster than dPB in both species. The incubation of dPB with RLMs and HLMs resulted in eight (B1–B8) and nine (B1–B9) metabolites, respectively, while both RLMs and HLMs converted dPE into 13 metabolites (E1–13). Structures of all the metabolites were proposed through comparing their mass data obtained via tandem mass spectrometry on an MSD ion trap system (IT‐MS/MS) coupled with high‐resolution mass measurement by time‐of‐flight mass spectrometry (TOF‐MS) with those of the respective parent compound. B1 and E1 were unambiguously identified as (−)‐cis‐khellactone. The formations of all the metabolites were NADPH‐dependent. Oxidation and hydrolysis were demonstrated to be two predominant metabolic pathways of dPB and dPE. Oxidation initiated at either the C‐3′ or C‐4′ substituent, while hydrolysis only started from the C‐3′ substituent. Fragmentation of all metabolites followed similar pathways to those of the parent pyranocoumarins. The information on metabolic properties of dPB and dPE and the mass fragmentation profiles of their metabolites obtained in the present study will aid in characterization of metabolic profiles of other angular‐type pyranocoumarins and further investigation of in vivo fates of these pyranocoumarins and the herb. Copyright © 2011 John Wiley & Sons, Ltd.
Physical signal modulation of time‐of‐flight mass analyzers increases precision and decreases noise
Authors: Hilmer Jonathan K. , Bothner Brian 
Published: February 2011

AbstractRecently, an increased emphasis has been placed on the ability to make mass measurements with high accuracy and precision. The motivation for this is that high‐precision mass measurements, together with isotope intensity matching, permit confirmation of molecular formulas and de novo molecular formula prediction, both of which enhance the value of proteomics and metabolomics data. The confidence of mass‐based conclusions also depends on reliable estimates of uncertainty. However, determining the precision of a particular measurement remains a complicated process. For signals which are well‐resolved and of sufficient intensity, an often‐overlooked factor for high precision is the mass sampling frequency (abscissa, Δx). We have analyzed the impact of Δx on the centroid calculation of peak position, and find that existing quality standards, such as 4 or 5 samples per peak, may not be sufficient to achieve high precision. Time‐domain and m/z‐domain sampling frequency on time‐of‐flight (TOF) mass analyzers can be improved using a new method that we call Physical Signal Modulation (PSM). PSM allows very substantial improvements by decreasing Δx without requiring specialized hardware or digitizers. In addition to providing accuracy improvements, PSM also dramatically improves signal‐to‐noise ratios by removing coherent noise. Software to perform PSM data processing is available as part of the PySpecTools package. Copyright © 2011 John Wiley & Sons, Ltd.
Robust performance analysis for uncertain negative‐imaginary systems
Authors: Song Zhuoyue , Lanzon Alexander , Patra Sourav , Petersen Ian R. 
Published: February 2011

SUMMARYNegative‐imaginary systems are important in engineering practice as this class of systems appears quite often in practical problems, for example, lightly damped flexible structures with collocated position sensors and force actuators. In this paper, an analytical framework for robust performance of uncertain negative‐imaginary systems is proposed. The results are obtained by transforming negative‐imaginary systems into a bounded‐real framework via the positive‐real property. This paper deals with all the significant technical difficulties that appear due to the transformation and the punctured j ω‐axis frequency condition of negative‐imaginary systems. The problem is equivalently cast into a structured singular value condition that gives a quantitative performance test for this class of systems. This result also gives an analytical framework for robust stability when the perturbations are mixture of bounded‐real and negative‐imaginary uncertainties. A numerical example is presented to show the usefulness of the proposed methods. Copyright © 2011 John Wiley & Sons, Ltd.
Robust impulsive control of motion systems with uncertain friction
Authors: van de Wouw N. , Leine R. I. 
Published: February 2011

SUMMARYIn this paper, we consider the robust set‐point stabilization problem for motion systems subject to friction. Robustness aspects are particularly relevant in practice, where uncertainties in the friction model are unavoidable. We propose an impulsive feedback control design that robustly stabilizes the set‐point for a class of position‐, velocity‐and time‐dependent friction laws with uncertainty. Moreover, it is shown that this control strategy guarantees the finite‐time convergence to the set‐point which is a favorable characteristic of the resulting closed loop from a transient performance perspective. The results are illustrated by means of a representative motion control example. Copyright © 2011 John Wiley & Sons, Ltd.
Standardization of Models and Methods Used to Assess Nanoparticles in Cardiovascular Applications
Authors: Fitzgerald Kathleen T. , Holladay Carolyn A. , McCarthy Cathal , Power Karen A. , Pandit Abhay , Gallagher William M. 
Published: February 2011

AbstractNanotechnology has the potential to revolutionize the management and treatment of cardiovascular disease. Controlled drug delivery and nanoparticle‐based molecular imaging agents have advanced cardiovascular disease therapy and diagnosis. However, the delivery vehicles (dendrimers, nanocrystals, nanotubes, nanoparticles, nanoshells, etc.), as well as the model systems that are used to mimic human cardiac disease, should be questioned in relation to their suitability. This review focuses on the variations of the biological assays and preclinical models that are currently being used to study the biocompatibility and suitability of nanomaterials in cardiovascular applications. There is a need to standardize appropriate models and methods that will promote the development of novel nanomaterial‐based cardiovascular therapies.
Scanning Transmission X‐Ray Microscopy as a Novel Tool to Probe Colloidal and Photonic Crystals
Authors: van Schooneveld Matti M. , Hilhorst Jan , Petukhov Andrei V. , Tyliszczak Tolek , Wang Jian , Weckhuysen Bert M. , de Groot Frank M. F. , de Smit Emiel 
Published: February 2011

AbstractPhotonic crystals consisting of nano‐ to micrometer‐sized building blocks, such as multiple sorts of colloids, have recently received widespread attention. It remains a challenge, however, to adequately probe the internal crystal structure and the corresponding deformations that inhibit the proper functioning of such materials. It is shown that scanning transmission X‐ray microscopy (STXM) can directly reveal the local structure, orientations, and even deformations in polystyrene and silica colloidal crystals with 30‐nm spatial resolution. Moreover, STXM is capable of imaging a diverse range of crystals, including those that are dry and inverted, and provides novel insights complementary to information obtained by benchmark confocal fluorescence and scanning electron microscopy techniques.
Vertical Arrays of Anisotropic Particles by Gravity‐Driven Self‐Assembly
Authors: Smith Benjamin D. , Kirby David J. , Keating Christine D. 
Published: February 2011

AbstractAnisotropic particles assemble to spontaneously form columnar arrays. Hybrid nanotube/nanowire particles (silica nanotubes partially filled with metallic cores) deposit with their denser metallic ends towards the surface, orienting them vertically. Up to 84% are observed to be standing over a 0.64 cm2 area within 15 min. Standing percentage is found to be dependent on particle surface concentration.
Isomorphous Catena Transition Metal Squarates [MII(C4O4)(dmso)2(OH2)2] (M = Co, Mn) and Magnetic Investigation into their Solid Solution M = CoxMn1–x
Authors: Şerb Mihaela‐Diana , Speldrich Manfred , Lueken Heiko , Englert Ulli 
Published: February 2011

AbstractThe crystal structures of two new isomorphous transition metal squarato complexes [MII(C4O4)(dmso)2(OH2)2] [MII = CoII (3d7), MnII (3d5); dmso = dimethylsulfoxide] and their magnetic properties are reported. The compounds feature two symmetrically independent chains, in which 1,3‐bridging squarato ligands connect cations in distorted octahedral surroundings of pseudo‐symmetry D4h. From an equimolar solution of CoCl2·6H2O and MnCl2·2H2O a mixed‐metal coordination polymer crystallizes; it represents a solid solution and adopts the same structure as the corresponding monometallic compounds. The results of the diffraction experiment unambiguously proof the presence of both CoII and MnII cations in either independent site albeit no precise ratio between the metal cations involved may be deduced from these findings. The difference in the magnetic properties between CoII and MnII cations in the given ligand field has allowed us to establish their ratio in the solid solution more reliably than by X‐ray diffraction: Accounting for ligand field potential and spin‐orbit coupling of CoII and regarding MnII as a pure spin system, the calculations yielded a fraction of 73 % CoII in the mixed‐metal polymer. With respect to superexchange effects only weak antiferromagnetic interactions have been detected for the three coordination polymers.
The Crystal and Molecular Structures of Gold(I) Complexes Containing the Electron‐Rich P‐Donor Ligand Ph3PNPPh2
Authors: Böttcher Hans‐Christian , Lux Karin , Kidik Mustafa , Karaghiosoff Konstantin 
Published: February 2011

AbstractThe reaction of [AuCl(tht)] (tht = tetrahydrothiophene) with an equimolar amount of the electron‐rich ligand N‐diphenylphosphino‐triphenylphosphinimine, Ph3PNPPh2, in THF afforded the new complex [AuCl(Ph3PNPPh2)] (1) in good yield. Furthermore, the reaction of [AuHCl4] with Ph3PNPPh2 in a molar ratio of 1:3 in dichloromethane at room temperature yielded the complex salt [Au(Ph3PNPPh2)2]Cl (2) as the dichloromethane solvate beside Ph3PNPPh2Cl2 as the side‐product of oxidation. The molecular structures of metal complexes 1 and 2 were determined by single‐crystal X‐ray diffraction. Because of the bulkiness of the ligand Ph3PNPPh2 no short intermolecular gold–gold interactions (aurophilic aggregation) could be observed in the solid‐state structures.