bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enthalpy assisted size exclusion chromatography Part 2. Adsorption retention mechanism
Authors: Russ Albert , Berek Dušan 
Published: June 2007

AbstractA novel high performance liquid chromatographic method for separation of synthetic polymers has been tested. It involves combination of the enthalpic and entropic retention mechanisms, resulting in increased selectivity of separation within a specific molar mass range. In this present case, the enthalpic retention mechanism is adsorption of macromolecules on a bare silica gel column packing. Under critical conditions of enthalpic interactions, homopolymers are known to elute irrespective of their molar mass. However, in the vicinity of critical conditions, a situation can be identified when retention volumes (VR) rapidly decrease with increasing molar mass. Typically, this happens for polymer species close to or above their exclusion limit observed with the same column in the absence of enthalpic interactions between macromolecules and packing, that is near “ideal SEC” conditions. The dependence of polymer retention volume on molar mass closely resembles size exclusion conditions. However, the witnessed rate of change in VR with polymer molar mass is more pronounced, thus indicating increased selectivity of separation. This situation not only offers the benefit of more selective separation according to molar mass but efficient discrimination of macromolecules possessing different nature and interactivity with the column packing can be accomplished as well.
Multiresidue analysis of four pesticide residues in water dropwort (Oenanthe javanica) via pressurized liquid extraction, supercritical fluid extraction, and liquid–liquid extraction and gas chromatographic determination
Authors: Jeon Hyang‐Rang , Abd El‐Aty Mostafa , Cho Soon‐Kil , Choi Jeong‐Heui , Kim Kil‐Yong , Park Ro‐Dong , Shim Jae‐Han 
Published: June 2007

AbstractThe primary objective of this study was to simultaneously analyze the residues of the most commonly used pesticides, chlorpyrifos‐methyl, endosulfan, EPN, and iprodione in the water dropwort, via accelerated solvent extraction (ASE), supercritical fluid extraction (SFE), and conventional solvent extraction (LLE) techniques. Residue levels were determined using GC with electron‐capture detection (GC‐ECD). The confirmation of pesticide identity was performed by GC‐MS in a selected ion‐monitoring (SIM) mode. In none of the ASE and SFE techniques were the extraction conditions optimized. Rather, the experimental variables were predicated on the author's experience. The ECD response for all pesticides was linear in the studied range of concentrations of 0.005–5.0 ppm, with correlation coefficients in excess of 0.9991. At each of the two studied fortification levels, the pesticides yielded recoveries in excess of 72% with RSDs between 1 and 19%. The LODs were achieved at a range of levels from 0.001 to 0.063 ppm, depending on the pesticide utilized. The LOQs, which ranged from 0.003 to 0.188 ppm, were lower than the maximum residue limits (MRLs) authorized by the Korean Food and Drug Administration (KFDA). All of the methods were applied successfully to the determination of pesticide residues in the real samples. It could, therefore, be concluded that any of the techniques utilized in this investigation might prove successful, given that the applied extraction conditions are wisely chosen.
A New Synthetic Method for the Preparation of Star‐Shaped Polyisobutylene with Hyperbranched Polystyrene Core
Authors: Kali Gergely , Szesztay Márta , Bodor Andrea , Iván Béla 
Published: June 2007

AbstractFriedel–Crafts self‐grafting of polystyrene (PSt) under quasiliving carbocationic polymerization was utilized to develop a new rapid one‐pot method for the preparation of star‐shaped polyisobutylene (PIB). First, the polymerization of isobutylene led to PIB with predetermined molecular weight ($\overline M _{\rm n}$ = 2 000) and narrow molecular weight distribution ($\overline M _{\rm w} /\overline M _{\rm n}$ = 1.03). Then addition of relatively small amount of styrene after isobutylene consumption yielded PIB‐PSt diblocks. Multiple alkylation of the resulting PSt segments by the polystyryl cations led to hyperbranched PSt cores coupling PIB chains to form a star polymer in short reaction time (within an hour) compared to reported methods. The formation of star polymers by this self‐grafting mechanism was proved by gel permeation chromatography equipped with online viscosimeter and 1H NMR spectroscopy.magnified image
Generalized convolutions for the Hankel transform and related integral operators
Authors: Britvina Lyubov' E. 
Published: June 2007

AbstractThe present research is devoted to some polyconvolutions generated by various integral transforms. For example, we study convolutions for the Hankel transform Hν [f ](x) with the following factorization properties:
equation image
Conditions for the existence of the constructed generalized convolutions are found.The results of this research are applied to construct and study integral transforms related to these polyconvolutions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On interaction of electromagnetic waves with infinite bianisotropic layered slab
Authors: Buchukuri Tengiz , Duduchava Roland , Sigua Levan 
Published: June 2007

AbstractA stratified general bianisotropic medium is considered, consisting of several infinite slabs either between two half‐spaces filled with isotropic material, or grounded. The slab is illuminated by an incident plane wave from one of the half‐spaces. The excited electromagnetic field inside the bianisotropic slab and in the isotropic domains is described. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wave scattering by an elastic obstacle with interior cuts
Authors: Castro Luís P. , Natroshvili David , Stratis Ioannis G. 
Published: June 2007

AbstractWe consider the direct interaction problem describing the scattering of acoustic waves by an elastic obstacle with interior cracks. By the potential method we reduce the problem to an equivalent system of integral (pseudodifferential) equations and study its solvability. In particular, we formulate necessary and sufficient conditions for the solvability in terms of the so‐called Jones modes. We show that the direct scattering problem is solvable for arbitrary values of the frequency parameter and for arbitrary incident wave functions if the crack surface is traction free. We also investigate the regularity of the displacement field, and analyze the stress singularities at the crack edge. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A note on commutator estimates for interpolation methods
Authors: Cerdà Joan 
Published: June 2007

AbstractThe aim of this note is to show how all the commutator estimates of two recent papers, by M. Cwikel, N. Kalton, M. Milman, and R. Rochberg and by N. Krugljak and M. Milman, can be considered as special cases of the method of couples of interpolators introduced by M. J. Carro, J. Cerdà and J. Soria, and also to show how the distance between orbits and the “Benson norm” considered by Krugljak and Milman can be extended, respectively, as a distance between the interpolators that appear in the general construction and as a constant that is finite when the interpolators satisfy the necessary cancellation property. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determinant calculations for the Block Szegő–Widom Limit Theorem
Authors: Ehrhardt Torsten 
Published: June 2007

AbstractThe Szegő–Widom Limit Theorem says that for certain N × N matrix functions φ defined on the unit circle, the asymptotic behavior of the determinants of the block Toeplitz matrices Tn (φ) is given by
equation image
where G [φ ] is the geometric mean of det φ and E [φ ] is equal to the operator determinant det T (φ)T (φ–1). In the scalar case (N = 1) a more explicit expression for E [φ ] exists, while in the matrix case (N > 1) not much is known.In the present paper we are going to establish an explicit expression for E [φ ] for 2 × 2 matrix functions φ = αI + βQ where α and β are scalar functions and Q is a rational matrix function for which Q2 = 0. It turns out that in comparison with the scalar case, new terms in the expression for E [φ ] appear. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sharpness and non‐compactness of embeddings of Bessel‐potential‐type spaces
Authors: Gogatishvili Amiran , Severino Neves Júlio , Opic Bohumír 
Published: June 2007

AbstractWe establish embeddings for Bessel potential spaces modeled upon Lorentz–Karamata spaces with order of smoothness less than one. The target spaces are of Hölder‐continuous type. In the super‐limiting case we also prove that the embedding is sharp and fails to be compact. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth envelope functions in Besov and Sobolev spaces. Local versus global results
Authors: Haroske Dorothee D. 
Published: June 2007

AbstractWe characterize the local and global behaviour of the growth envelope functionequation imagefor spacesXof Sobolev and Besov type, as well as for some weighted spaces. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Singular operators in variable spacesLp(·)(Ω,ρ) with oscillating weights
Authors: Kokilashvili Vakhtang , Samko Natasha , Samko Stefan 
Published: June 2007

AbstractWe study the boundedness of singular Calderón–Zygmund type operators in the spacesLp(·)(Ω,ρ) over a bounded open set in ℝnwith the weightρ(x) =$ \prod ^m_{k=1} $wk(|x–xk|),xk∈$ \bar \Omega $, wherewkhas the property that$ r^{ {n \over {p(x_k)}} } $wk(r) ∈$ \Phi ^0_n $, where$ \Phi ^0_n $is a certain Zygmund‐type class. The boundedness of the singular Cauchy integral operatorSΓalong a Carleson curve Γ is also considered in the spacesLp(·)(Γ,ρ) with similar weights.The weight functionswkmay oscillate between two power functions with different exponents. It is assumed that the exponentp(·) satisfies the Dini–Lipschitz condition. The final statement on the boundedness is given in terms of the index numbers of the functionswk(similar in a sense to the Boyd indices for the Young functions defining Orlicz spaces). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Potentials of Gaussians and approximate wavelets
Authors: Maz'ya Vladimir , Schmidt Gunther 
Published: June 2007

AbstractWe derive new formulas for harmonic, diffraction, elastic, and hydrodynamic potentials acting on anisotropic Gaussians and approximate wavelets. These formulas can be used to construct accurate cubature formulas for these potentials. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Posing an inverse problem for the Helmholtz equation in a half plane
Authors: Penzel Frank 
Published: June 2007

AbstractIn this paper we shall define an inverse problem for the Helmholtz equation with imaginary part of the wave number being positive. The Cauchy data are known on the boundary of the half plane, but it is not known where the half axis, lying vertically in the upper half plane, is situated. It is known that the Dirichlet data on that unknown boundary is vanishing.The direct problem may be reduced to the solution of a boundary value problem in the plane where the boundary consists of two vertically lying half axes in the plane. We shall present the explicit solution of the direct problem and we shall discuss conditions on the Cauchy data for solvability of the inverse problem. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wavelets in function spaces on Lipschitz domains
Authors: Triebel Hans 
Published: June 2007

AbstractThe spaces $ B^s_{pq} $(ℝn ) and $ F^s_{pq} $(ℝn ) can be characterized in terms of Daubechies wavelets for all admitted parameters s, p, q. The paper deals with related intrinsic wavelet frames (which are almost orthogonal bases) in corresponding (sub‐)spaces on bounded Lipschitz domains under some restrictions for the parameters. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On nonlinear Riemann–Hilbert problems with discontinuous boundary condition
Authors: Efendiev M. A. , Wendland W. L. 
Published: June 2007

AbstractFor holomorphic functions in the unit disc, we consider a general nonlinear boundary condition whose linearisation admits jump discontinuities at a finite number of points on the unit circle, the boundary of the unit disc. By using the properties of quasilinear Fredholm maps of the corresponding nonlinear Cauchy singular integral equation, the appropriate choice of the Gochberg–Krupnik index and a homotopy with linear Riemann–Hilbert problems with discontinuous coefficients, we show that the degree of mapping of the quasilinear Fredholm map is nonzero. This guaranties the existence of solutions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unprecedented Blue Intrinsic Photoluminescence from Hyperbranched and Linear Polyethylenimines: Polymer Architectures and pH‐Effects
Authors: Pastor‐Pérez Lourdes , Chen Yu , Shen Zhong , Lahoz Agustin , Stiriba Salah‐Eddine 
Published: June 2007

AbstractThe intrinsic photoluminescence properties of hyperbranched polyethylenimines (PEIs) and their linear counterpart (LPEIs) have been studied in absence of any classical fluorescent probes. The comparison of the inherent fluorescence emission between hyperbranched polyethylenimines and their linear analogues demonstrates that linear polyamines are capable of producing strong intrinsic photoluminescence species having long excited lifetimes without need of having a tridimensional‐branched structure. The creation of inherently fluorescent polymeric centers from hyperbranched and linear polyethyleimines can be modulated by specific chemical modification and oxidation of amine groups as well as by adjusting the acidity of the polymer.magnified image
Grundlagen, Herstellung und Anwendungsaspekte des Supersolidus Flüssigphasensinterns von hochlegierten Werkzeugstählen und Metallmatrix‐Verbundwerkstoffen
Authors: Weber S. , Theisen W. 
Published: June 2007

AbstractMetallmatrix Verbundwerkstoffe (MMC) auf Eisenbasis finden Anwendung zum Schutz gegen grob abrasiven Verschleiß. Ihre pulvermetallurgische Fertigung (PM) erfolgt üblicherweise durch Heiß‐Isostatisches Pressen (PM‐HIP) metallischer und karbidischer Pulver, einem vergleichsweise aufwändigem Verfahren, das mit hohen Kosten verbunden ist. Unter Verwendung eines hochlegierten Werkzeugstahles als Matrixwerkstoff kann die Herstellung auch über einen Sinterprozess unter Beteiligung einer inneren flüssigen Phase erfolgen. Der Beitrag beschreibt die Grundlagen zur Verdichtung der Matrixwerkstoffe unter Berücksichtigung thermodynamischer Berechnungen und zeigt einen Weg zur Herstellung partikelverstärkter, verschleißbeständiger Verbundwerkstoffe auf. Neben dem Sinterverhalten werden Wärmebehandlungskonzepte sowie das abrasive Verschleißverhalten gesinterter Werkstoffe besprochen.
A pilot, double‐blind, placebo‐controlled trial of pregabalin (Lyrica) in the treatment of essential tremor
Authors: Zesiewicz Theresa A. , Ward Christopher L. , Hauser Robert A. , Salemi Jason L. , Siraj Shaila , Wilson Maria‐Carmen , Sullivan Kelly L. 
Published: June 2007

AbstractWe performed a pilot, double‐blind, placebo‐controlled, randomized trial to evaluate the efficacy and tolerability of pregabalin (PGB, Lyrica), an antiepileptic agent, in treating essential tremor (ET). Twenty two patients with ET were randomly assigned to receive PGB or placebo. PGB was initiated at 50 mg/day and was escalated by 75 mg/day every 4 days to a maximum dose of 600 mg/day. Patients were evaluated by accelerometry and the Fahn–Tolosa–Marin (FTM) rating scale. There was a significant reduction in tremor amplitude in the PGB group compared with the placebo group, as measured by accelerometry, at a mean dose of 286.76 ± 100.05 mg/day. Action tremor limb scores on the FTM also improved in the PGB group compared with the placebo group (P‐value for multilevel modeling = 0.04). PGB was fairly well tolerated, with about one‐third of patients dropping out of the study because of adverse events. PGB provided significant improvements in accelerometry and in action tremor limb scores on the FTM. However, larger studies are needed to further evaluate the potential effect of PGB on ET. © 2007 Movement Disorder Society
A CMOS RF predistorter using diode‐connected MOSFET
Authors: Ko Sangwon , Lin Jenshan 
Published: June 2007

AbstractIn this paper, a RF predistorter designed using a CMOS process is reported. In GaAs circuits, a Schottky diode has been used as a nonlinear element in the hybrid type predistorter linearizer. We propose a diode‐connected MOS transistor as an alternative nonlinear element in CMOS process. For the analysis, the idea of a dynamic impedance line is introduced and the large signal equivalent parameters of the nonlinearity generation circuit are extracted from the simulation. A 2.4 GHz CMOS power amplifier is designed using a 0.18‐μm CMOS 1P6M mixed‐mode process and the proposed predistorter is fully integrated with the CMOS power amplifier in a single chip. The measured results match with the simulation results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2055–2057, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22646
On the design of multifrequency dividers suitable for GSMsol;DCS/PCS/UMTS applications by using a particle swarm optimization‐based technique
Authors: Zaharis Zaharias D. , Kampitaki Dimitra G. , Lazaridis Pavlos I. , Papastergiou Anastasia I. , Gallion Philippe B. 
Published: June 2007

AbstractA particle swarm optimization‐based technique is applied to design dividers that operate in two or more frequency bands at once. The geometry of the dividers is optimized under specific requirements concerning the impedance‐matching bandwidth and the complex current distribution on unmatched real or complex terminal loads for each one of the resonant frequencies. The required current distribution on the loads concerns not only the ratio between the current amplitudes but also the phase difference between the currents. Several cases are studied to show the robustness of the particle swarm optimizer as well as the ability of the technique to derive optimal multifrequency structures suitable for GSM/DCS/PCS/UMTS applications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2138–2144, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22658
Analysis of electromagnetic band‐gap waveguide structures using body‐of‐revolution finite‐difference time‐domain method
Authors: Tong Ming‐Sze , Sauleau Ronan , Rolland Anthony , Chang Tae‐Gyu 
Published: June 2007

AbstractStudy of electromagnetic band‐gap (EBG) structures has become a hot topic in computational electromagnetics. In this article, some EBG structures integrated inside a circular waveguide are studied. They are formed by a series of air‐gaps within a circular dielectric‐filled waveguide. A body‐of‐revolution finite‐difference time‐domain (BOR‐FDTD) method is adopted for analysis of such waveguide structures, due to their axial symmetric properties. The opening ends of the waveguide are treated as a matched load using an unsplit perfectly matched layer technique. Excitations on a waveguide in BOR‐FDTD are demonstrated. Numerical results of various air‐gap lengths with respect to the period of separation are given, showing an interesting tendency of EBG behavior. A chirping‐and‐tapering technique is applied on the EBG pattern to improve the overall performance. The proposed EBG structures may be applied into antenna structures or other system for unwanted signal suppression. Results show that the BOR‐FDTD offers a good alternative in analyzing axial symmetric configurations, as it offers enormous savings in computational time and memory comparing with a general 3D‐FDTD algorithm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2201–2206, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22668
Rayleigh parameter of a rough layer: Application to forward radar propagation over oil slicks on sea surfaces under the Ament model
Authors: Pinel Nicolas , Bourlier Christophe , Saillard Joseph 
Published: June 2007

AbstractThe well‐known Rayleigh parameter, which characterizes the degree of roughness of a corrugated surface for the case of reflection on a rough surface, is extended to the reflection on a rough layer. An application to the forward radar propagation over oil slicks on sea surfaces, using the Ament model, is given. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2285–2290, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22716
A new inspection method applying to CMOS image sensor bumping
Authors: Chen Der‐Chin , Lin Chan‐Chun 
Published: June 2007

AbstractThis article demonstrates a new optical technique, which we apply to the collimating system to measure the parallel degree of CMOS (Complementary Metal‐Oxide Semiconductor) image sensor bumping. We research and develop the new adjustable auto‐collimating system to simplify the testing of CMOS board alignment and to increase the image quality of the cell phone camera. This method is a non‐contact method for testing and can detect the parallel degree deviation to an accuracy of 0.5°. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2283–2285, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22717
Couplings control in a compact microstrip dual‐mode resonator
Authors: Banciu M. G. , Ioachim A. , Ramer R. , Militaru N. , Lojewski G. 
Published: June 2007

AbstractA compact microstrip dual‐mode resonator with slots in the ground plane is presented in this paper. Several methods for coupling between the dual modes are investigated. One of the methods involves using slots in the ground plane in order to enhance the external coupling and to introduce the necessary perturbation to the initially symmetrical structure. The proposed device requires a surface area about 6 times smaller than the area needed for a conventional patch dual‐mode resonator. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2290–2295, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22722
Investigations into the Chemical Modification of Polyolefin Surfaces by Radical Reactions during Molding
Authors: Nagel Jürgen , Brunotte René , Hupfer Bernd , Grundke Karina , Lehmann Dieter , Mennig Günter 
Published: June 2007

AbstractThe surfaces of polyolefin parts are usually modified by separate processing steps. In this paper, we investigate how an in situ surface modification of polyolefins could be realized during molding, based on radical reactions, by which a macromolecule with functional groups is grafted to the polyolefin surface. The temperature of the melt is used to initialize the reactions. The different steps of the radical reaction chain were analyzed using model reactions. A modifier composition consisting of dibenzoylperoxide, potassium persulfate and poly(vinyl alcohol) revealed to be suitable. This composition was used for injection molding experiments. The bondability of the injection molded parts was largely enhanced.magnified image