bluuebunny/crossref_metadata_2025_split huggingface dataset:
One‐Step Growth of ca. 2–15 nm Polymer Thin Films on Hydrogen‐Terminated Silicon
Authors: Blake Robert B. , Pei Lei , Yang Li , Lee Michael V. , Conley Hiram J. , Davis Robert C. , Shirahata Naoto , Linford Matthew R. 
Published: April 2008

AbstractHere we show direct polymer growth on hydrogen‐terminated silicon (SiH) as a one‐step process. SiH is immersed in a heated solution of an initiator, a monomer, and a crosslinker. The resulting polymer films are 2–15 nm thick, the thickness can be tuned by varying reaction conditions, and the polymer films are robust. Thinner films are obtained in polymer growth without crosslinker. Radicals produced by the initiator and in growing polymer chains may pluck H atoms from SiH to make reactive dangling bonds. These in turn appear to react with monomers and crosslinkers. Crosslinkers tethered through one double bond may be grafted into polymer chains growing in solution. Surface reactivity is demonstrated by optical ellipsometry, X‐ray photoelectron spectroscopy, atomic force microscopy, and wetting.magnified image
A defect correction method for the time‐dependent Navier‐Stokes equations
Authors: Labovschii A. 
Published: April 2008

AbstractA method for solving the time dependent Navier‐Stokes equations, aiming at higher Reynolds' number, is presented. The direct numerical simulation of flows with high Reynolds' number is computationally expensive. The method presented is unconditionally stable, computationally cheap, and gives an accurate approximation to the quantities sought. In the defect step, the artificial viscosity parameter is added to the inverse Reynolds number as a stability factor, and the system is antidiffused in the correction step. Stability of the method is proven, and the error estimations for velocity and pressure are derived for the one‐ and two‐step defect‐correction methods. The spacial error is O(h) for the one‐step defect‐correction method, and O(h2) for the two‐step method, where h is the diameter of the mesh. The method is compared to an alternative approach, and both methods are applied to a singularly perturbed convection–diffusion problem. The numerical results are given, which demonstrate the advantage (stability, no oscillations) of the method presented. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Error estimates of finite volume element method for the pollution in groundwater flow
Authors: Zhang Zhiyue 
Published: April 2008

AbstractIn this article, we study the finite volume element methods for numerical solution of the pollution in groundwater flow in a two‐dimensional convex polygonal domain. These type flow are uniform transport in a fully saturated incompressible porous media, which may be anisotropic with respect to hydraulic conductivity, but features a direction independent of dispersivity. A fully finite volume scheme is analyzed in this article. The discretization is defined via a planar mesh consisting of piecewise triangles. Optimal order error estimates in H1 and L2 norms are obtained. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Application of 16O/18O reverse proteolytic labeling to determine the effect of biofilm culture on the cell envelope proteome of Porphyromonas gingivalis W50
Authors: Ang Ching‐Seng , Veith Paul D. , Dashper Stuart G. , Reynolds Eric C. 
Published: April 2008

AbstractPorphyromonas gingivalis is an oral pathogen linked to chronic periodontitis. The bacterium exists as part of a polymicrobial biofilm accreted onto the tooth surface. An understanding of the changes to the proteome especially of the cell envelope of biofilm cells compared with planktonic cells could provide valuable insight into the molecular processes of biofilm formation. To establish which proteins changed in abundance between the planktonic and biofilm growth states, the cell envelope fractions of two biological replicates of P. gingivalis cultivated in a chemostat were analysed. Proteins were separated by 1‐D SDS‐PAGE, in‐gel digested with trypsin in the presence of H216O or H218O and identified and quantified by LC‐MALDI TOF/TOF‐MS. Using a reverse labeling strategy we identified and quantified the changes in abundance of 81 P. gingivalis cell envelope proteins. No form of bias between the labels was observed. Twenty four proteins increased in abundance and 18 decreased in abundance in the biofilm state. A group of cell‐surface located C‐Terminal Domain family proteins including RgpA, HagA, CPG70 and PG99 increased in abundance in the biofilm cells. Other proteins that exhibited significant changes in abundance included transport related proteins (HmuY and IhtB), metabolic enzymes (FrdAB) and immunogenic proteins.
Proteomic investigation of the adaptation of Lactococcus lactis to the mouse digestive tract
Authors: Roy Karine , Meyrand Mickaël , Corthier Gérard , Monnet Véronique , Mistou Michel‐Yves 
Published: April 2008

AbstractLactic acid bacteria are used on an industrial scale for the manufacturing of dairy products. It is now intended to develop novel applications of lactic acid bacteria that could be used as living vehicles for the targeting of antigens or therapeutics to the digestive mucosa. The aim of this study was to analyze the adaptations of Lactococcus lactis, a model lactic acid bacteria to the digestive tract and to identify functions required for colonization of the intestine. For this purpose, we combined gnotobiology with proteomics: axenic mice were colonized with a dairy L. lactis strain and the bacterial proteome was examined by 2‐DE. As compared to cultures in broth, the proteome profile of bacteria grown in the intestine indicates the activation of metabolic pathways involved in various carbon sources assimilation and suggests the adoption of a mixed acids fermentative metabolism. We identified the product of the ywcC gene as essential for the colonization of the digestive tract and demonstrated that the corresponding gene product (YwcC) possesses a phosphogluconolactonase activity, suggesting an important role of the pentose phosphate pathway for the development of L. lactis in the digestive environment.
Serum protein profiling in mice: Identification of Factor XIIIa as a potential biomarker for muscular dystrophy
Authors: Alagaratnam Sharmini , Mertens Bart J. A. , Dalebout Johannes C. , Deelder André M. , van Ommen Gert‐Jan B. , den Dunnen Johan T. , 't Hoen Peter A. C. 
Published: April 2008

AbstractProtein profiling in blood serum by fractionation and MS analysis has been applied in mice to assess its applicability as a fast, economical alternative to current DNA and RNA analyses for diagnosis of neuromuscular disorders. Mass spectra of peptides and proteins were generated using serum from dystrophin‐deficient mdx and control mice by WCX ClinProt bead fractionation, followed by MALDI‐MS. Double cross‐validatory linear discriminant and logistic regression data analysis methods were compared with a new Bayesian logistic regression method. These were evaluated on their ability to discriminate between healthy and dystrophic samples, and to identify the discriminatory peaks in the mass spectra. All three approaches classified the spectra with comparable misclassification rates (between 18.4 and 20.6%), with much overlap between the differential peaks identified between the methods. The differential peak pattern from the Bayesian method was sparser and easier to interpret than from the other two methods, without compromising classifying strength. One of the two main differentiating peaks at m/z 3908 was identified as an N‐terminal peptide of coagulation Factor XIIIa, previously identified in human serum. This work underlines the translational aspect of serum protein profiling in mice and supports a further study with serum from patients with neuromuscular disorders.
Synthesis and characterization of carboxylic acid‐terminated polyisobutylenes
Authors: Kemp Lisa K. , Donnalley Andrew B. , Storey Robson F. 
Published: April 2008

Abstracttert‐Chloride‐terminated polyisobutylenes (PIB) (1020 ≤Mn≤ 6700 g/mol) were dehydrochlorinated nonregiospecifically using basic alumina, or regiospecifically either via potassiumtert‐butoxide orin situquenching of quasiliving PIB. Olefin‐terminated PIBs were quantitatively ozonized at −78 °C using hexane/methylene chloride/methanol, 62/31/7 (v/v/v) cosolvents, and an ozone generator, employing pure oxygen as source gas. The primary ozonides were reduced using trimethyl phosphite to yield pure PIB methyl ketone fromexo‐olefin PIB, and a mixture of PIB methyl ketone and PIB aldehyde from mixed olefin‐PIB. PIB methyl ketone was oxidized to carboxylate via the haloform reaction; titration revealed near‐quantitative functionalization, but the reaction was slow. Tetrahalomethane oxidation was identified as a preferred alternative method, and was conducted using either CCl4as the reaction solvent, THF as the solvent with CCl4in reagent amounts, or hexane as the solvent with a phase‐transfer catalyst and CCl4in reagent amounts. The system using hexane, with tetra‐n‐butyl ammonium chloride as phase‐transfer catalyst, showed complete conversion in ∼ 4 h. PIB carboxylic acid was recovered by acidification and isolation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3229–3240, 2008
Graft copolymerization of 2‐methacryloyloxyethyl phosphorylcholine to cellulose in homogeneous media using atom transfer radical polymerization for providing new hemocompatible coating materials
Authors: Yan Lifeng , Ishihara Kazuhiko 
Published: April 2008

AbstractTo develop new hemopurification systems based on cellulose membrane, we synthesized a graft copolymer of cellulose with poly(2‐methacryloyloxyethyl phosphorylcholine) (MPC) by a metal‐catalyzed atom transfer radical polymerization process in homogeneous media. First, cellulose was dissolved in a DMAc/LiCl solution system, and it reacted with 2‐bromoisobutyloyl bromide to produce macroinitiator (cell‐BiB). Then, MPC was polymerized to the cellulose backbone in a homogeneous DMSO/methanol mixture solution in the presence of cell‐BiB. Characterization with FT‐IR, NMR, and GPC measurements showed that there obtained a graft copolymer of cellulose backbone and poly(MPC) side chains (cell‐PMPC) with well‐defined structure, indicating a controlled/“living” radical polymerization. The proteins adsorption studies showed that cellulose membranes modified by the as‐prepared cell‐PMPC owns good protein adsorption resistance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3306–3313, 2008
Extension of RDG‐FA for Scattering Prediction of Aggregates of Soot Taking into Account Interactions of Large Monomers
Authors: Yon Jérôme , Rozé Claude , Girasole Thierry , Coppalle Alexis , Méès Loïc 
Published: April 2008

AbstractThe characterization of soot fractal aggregate, i.e., morphology, size, number and volume fraction, by optical diagnostics is very widespread since it is a sensitive and nonintrusive technique. In general, light absorption or scattering by fractal aggregates is quantitatively interpreted by the Rayleigh‐Debye‐Gans for Fractal Aggregates (RDG‐FA) theory due to its simplicity. Nevertheless, important conditions have to be obeyed for the correct use of this theory. Among them, aggregates and primary particles have to be very small in comparison to the wavelength. In addition, internal scattering must be negligible. Moreover, the form factor functions that allow the fractal morphology to be taken into account have been established for a polydispersed population. In contrast to previous studies that evaluated the valid RDG‐FA range by comparing the difference between rigorous calculations and the RDG‐FA approach, the aim of the present study is to evaluate possible corrections that could be applied to the classical RDG‐FA formula in order to take into account of aggregates and primary particles internal multiscattering. Therefore, new generalized form factors are proposed allowing the evaluation of the optical properties of one aggregate with a primary particle diameter of up to 90 nm, without any assumptions concerning aggregate complex internal interactions. The presented results are based on the assumption that DDSCAT (Discrete Dipole Approximation) provides accurate results, with a wavelength, λ = 632 nm, a soot fractal dimension of 1.8 and Dalzel and Sarofim optical index, m = 1.57 – i0.56.
Excited state properties of neutral and charged ter‐fluorene with and without a keto‐defect
Authors: Beenken W. J. D. , Sun M. , Zhao G. , Pullerits T. 
Published: April 2008

AbstractStimulated by the recent experimental report of optical properties of charged oligofluorenes [S. Fratiloiu et al., J. Phys. Chem. B 110, 5984–5993 (2006)], we have used time‐dependent density functional theory (TD‐DFT) to study the electronic structure of neutral and charged ter‐fluorene with and without keto‐defect. We have characterized the excited states by site‐ and space‐based representations of the density matrix. For the defectless neutral species we found typical excitons, while the first excited states of the corresponding charged species represent long‐range oscillations of the electron or hole along the whole oligomer. For the neutral ketonized ter‐fluorene we found trapping of the excited electron. Similarly, the unpaired electron of the anion ground state is trapped. The excited state properties of the cation, however, are insensitive to the keto‐defect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polariton relaxation after resonant pumping at the upper polariton branch under doubly‐resonant Raman scattering conditions
Authors: Martín M. D. , Ballarini D. , Amo A. , Viña L. , André R. 
Published: April 2008

AbstractWe have investigated the influence of polariton–phonon interaction on the relaxation of microcavity polaritons towards the bottom of the lower polariton branch (LPB). We have varied either the energy difference between the two polariton branches at K ∼ 0 (negative detuning) or the Rabi splitting (zero detuning), adjusting them to coincide with the energy of a LO‐phonon. We have observed a sub‐linear/super‐linear increase of the LPB emission with pump power for negative/zero detuning, respectively. These different power dependencies can be explained by the combined effect of the different polariton–phonon scattering efficiency, which is minimum/maximum for large negative/zero detunings, a competition between several relaxation mechanisms and the different coupling to the excitonic reservoir of large‐K LPB states. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface electronic properties of n‐ and p‐type InGaN alloys
Authors: King P. D. C. , Veal T. D. , Lu Hai , Jefferson P. H. , Hatfield S. A. , Schaff W. J. , McConville C. F. 
Published: April 2008

AbstractX‐ray photoemission spectroscopy is utilised to determine the variation in surface Fermi level pinning across the composition range of n‐ and p‐type c ‐plane Inx Ga1–x N alloys. The pinning relative to the charge neutrality level is used to explain a change in band bending direction causing a transition from surface electron accumulation (In‐rich) to depletion (Ga‐rich) at x ≈ 0.43 for n‐type alloys and a transition from surface inversion to hole depletion at x ≈ 0.59 for p‐type alloys where downward band bending occurs across the composition range. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plasma‐assisted MBE growth of (11$ \bar 2 $2)‐oriented GaN/AlN quantum wells on m‐sapphire
Authors: Lahourcade L. , Renard J. , Kandaswamy P. K. , Gayral B. , Monroy E. 
Published: April 2008

AbstractWe report on the plasma‐assisted molecular‐beam epitaxy growth of two‐dimensional (11$ \bar 2 $2)‐oriented AlN, GaN and GaN/AlN multiple quantum well (MQW) structures on (1$ \bar 1 $00) m ‐plane sapphire. Moderate N‐rich conditions enable to synthesize AlN(11$ \bar 2 $2) directly on m ‐sapphire, with inplane epitaxial relationships [11$ \bar 2 $$ \bar 3 $]AlN || [0001]sapphire and [1$ \bar 1 $00]AlN || [11$ \bar 2 $2]sapphire. In the case of GaN a Ga‐excess of one monolayer is necessary to achieve two‐dimensional growth of GaN(11$ \bar 2 $2). Applying the adequate growth conditions, we demonstrate the synthesis of (11$ \bar 2 $2)‐oriented GaN/AlN MQW structures. The reduction of the luminescence red shift and of the luminescence decay time compared to standard polar structures confirms the quantum confined Stark effect attenuation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct optical measurement of hot‐phonons in active AlGaN/GaN devices
Authors: Pomeroy J. W. , Kuball M. , Uren M. J. , Martin T. 
Published: April 2008

AbstractWe demonstrate the direct detection of hot‐phonons in the channel of active AlGaN/GaN HFETs by combining anti‐Stokes Raman scattering with conventional Raman thermography. Hot‐phonon temperatures were found to be consistent with hot‐electron temperatures determined using electroluminescence measurements. Temperatures reach as high as 1000 K for 30 V source–drain biases. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Band structure and effective mass of InN under pressure
Authors: Gorczyca I. , Dmowski L. , Plesiewicz J. , Suski T. , Christensen N. E. , Svane A. , Gallinat C. S. , Koblmueller G. , Speck J. S. 
Published: April 2008

AbstractCalculations of the electronic band structure and effective mass of InN are performed within the density functional theory by means of the linear muffin‐tin‐orbital method. The results show a pronounced nonparabolicity of the conduction band. Calculated variations of the highest occupied conduction band energy and electron effective mass with free electron concentration are presented and compared to available experimental data. Pressure effects are studied. Both the fundamental band gap and the electron effective mass increase with hydrostatic pressure, but due to the nonparabolic character of the conduction band of InN the pressure coefficient of the effective mass decreases with electron concentration. Experimental verification of this behavior has been performed on three n‐type samples of InN with different electron concentrations. The measurements and calculations agree in the description of the dependence of effective mass and its pressure coefficient on electron concentration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Free‐standing zinc‐blende (cubic) GaN substrates grown by a molecular beam epitaxy process
Authors: Foxon C. T. , Novikov S. V. , Stanton N. M. , Campion R. P. , Kent A. J. 
Published: April 2008

AbstractIn this paper bulk, free‐standing, zinc‐blende (cubic) GaN wafers grown by plasma‐assisted molecular beam epitaxy (PA‐MBE) are described. GaN layers of up to 60 microns in thickness have been grown. Characterisation measurements confirm the cubic nature of the GaN crystals and show that the fraction of hexagonal material present is not more than ∼10%. Cubic (001)GaN does not exhibit the spontaneous and piezoelectric polarization effects associated with (0001) c‐axis wurtzite GaN. Free standing GaN wafers grown by PA‐MBE make ideal lattice‐matched substrates for the growth of cubic GaN‐based structures for optoelectronic devices, and high power and high frequency electronic applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unintentional doping in GaN assessed by scanning capacitance microscopy
Authors: Sumner J. , Bakshi S. Das , Oliver R. A. , Kappers M. J. , Humphreys C. J. 
Published: April 2008

AbstractUsing scanning capacitance microscopy (SCM) we observe a layer of unintentional n‐type conductivity in GaN/sapphire epilayers in a region adjacent to the GaN/sapphire interface. It is shown to have a carrier concentration of (1.66 ± 0.08) × 1018 cm–3. Secondary ion mass spectroscopy (SIMS) data from a similar sample suggests that the n‐type conductivity in this region results from unintentional oxygen incorporation. Various doped regions are also observed in epitaxial lateral over‐growth (ELOG) samples. GaN initially grows through a SiNx mask forming faceted stripes, which exhibit unintended n‐type conductivity. Magnesium is used to enhance stripe coalescence, resulting in p‐type regions. The top layer, grown following coalescence, appears non‐conducting. The different electron concentrations found within the ELOG cross‐section could correspond to the different facets formed during growth which may indicate that the changes in carrier concentration reflect the rate of impurity incorporation on each facet. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiple carrier transport in N‐face indium nitride
Authors: Fehlberg Tamara B. , Koblmüller Gregor , Umana‐Membreno Gilberto A. , Gallinat Chad S. , Nener Brett D. , Speck James S. , Parish Giacinta 
Published: April 2008

AbstractWe present temperature (20–300 K) dependent multi‐carrier measurements of electron species in N‐face indium nitride. N‐face InN samples were grown to different thicknesses (500–2000 nm) via plasma‐assisted molecular beam epitaxy on C‐face SiC substrates. Surface and bulk electron transport properties were extracted using a quantitative mobility spectrum analysis. Mobility of both bulk and surface electron species increase with film thickness. The temperature dependence of the mobility of both species differs to that of In‐polar samples studied previously, while the mobility of surface electrons is more than twice that of In‐polar samples with only a slight corresponding reduction in sheet concentration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular dynamics and first‐principles computations of Ga adlayers on GaN(0001)
Authors: Rinehimer J. A. , Widom M. , Northrup J. E. , Feenstra R. M. 
Published: April 2008

AbstractStructural models for Ga adlayer(s) on GaN(0001) are investigated using both molecular dynamics and first‐principles computations. An energetically favourable model is deduced that is consistent with observed low‐energy electron diffraction data. The model contains regions of uniaxial contraction of the topmost Ga adlayer on the surface (rather than uniform biaxial contraction, as in previous models), multiple domains of which form a hexagonal arrangement on the surface. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Very strong nonlinear optical absorption in green GaInN/GaN multiple quantum well structures
Authors: Zhao W. , Zhu M. , Xia Y. , Li Y. , Senawiratne J. , You S. , Detchprohm T. , Wetzel C. 
Published: April 2008

AbstractThe efficiency of green GaInN/GaN light emitting diodes (LEDs) is known to drop under high current densities. To explore the reason, 535 nm emitting GaInN/GaN multiple quantum well (MQW) and GaN epilayers were characterized using Z‐scan techniques under comparable excitation conditions with a continuous wave laser. Two wavelengths, 514 nm and 488 nm, were selected right below and above the apparent optical absorption edge. At 514 nm, a very large nonlinear absorption coefficient β = 2.6 cm/W was obtained. This leads to a 20% absorption enhancement at a photon flux of 21 kW/cm2. We attribute this to nonlinear free‐carrier absorption. On the other hand, at 488 nm, a nonlinear saturable absorption with β = –1.7 cm/W was observed. This induced transparency indicates photon bleaching in the MQW. Apparently, free carrier dynamics strongly affects optical nonlinearity, while nonlinear absorption provides a small contribution to the limitations of current green LEDs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)