bluuebunny/crossref_metadata_2025 huggingface dataset:
Bichromatic spectroscopy of coherent population trapping resonances with phase‐locked fields
Authors: Akimov A. V. , Matveev A. N. , Sokolov A. V. , Sorokin V. N. , Kanorsky S. I. , Kolachevsky N. N.
Published: February 2005

We propose a new approach to the study of coherent population trapping (CPT) resonances using a phase‐coherent bichromatic light source based on a mode‐locked femtosecond laser as an intermediate frequency coupler. The source consists of two diode lasers tuned to the rubidium D2 line (780 nm) which are phase locked to different longitudinal modes of a femtosecond laser MIRA‐900F with 75 MHz repetition rate. Using this bichromatic source with a stable differential frequency, we excited and investigated the CPT resonances in the three‐level system 5s S1/2 (F = 2) ↔ 5s P3/2 (F = 2) ↔ 5s S1/2 (F = 3) of the 85Rb atom. Potentially, this method opens up the possibility of coherently exciting Raman transitions with differential frequencies up to hundreds of terahertz. Copyright © 2005 John Wiley & Sons, Ltd.
Influence of the dehydration process on active compounds of okara during its fractionation
Authors: Surel Olivier , Couplet Blandine
Published: February 2005

Okara (residue of the soymilk manufacture) is rich in proteins, fibres and lipids. It also contains isoflavones that possess health‐promoting properties. A new method has been developed for the valorization of fibres from okara by hydrolysis of insoluble proteins with a protease and removal of the oil. Three different processes were investigated: the first one involved delipidation and drying prior to proteolysis and led to the highest content of fibre (80%) in the final product. The second used proteolysis on crude okara followed by solvent delipidation–dehydration and gave an intermediate content of fibre (75%). The last process was totally enzymatic (proteolysis and lipolysis) and gave the lowest content of fibre in the final product (50%). Fibre water‐holding capacity was correlated to the total dietary fibre content of each sample. It was preferable to use crude okara for hydrolysis, since oven‐drying during the process decreased the water‐holding capacity and modified the isoflavone profile of okara. Copyright © 2005 Society of Chemical Industry
Proximate composition and free radical scavenging activity of edible fruits from the Argentinian Yungas
Authors: Schmeda‐Hirschmann Guillermo , Feresin Gabriela , Tapia Alejandro , Hilgert Norma , Theoduloz Cristina
Published: February 2005

The proximate composition and free radical scavenging effect of native food plants gathered in the Argentinian Yungas have been assessed. Some 25 samples were collected for proximate analysis and free radical scavenging effect of their MeOH‐soluble extracts. Total acidity, phenolics and solid content of 16 preserves prepared from native fruits have been determined. The samples belong to 13 different species corresponding to eight plant families, mainly Myrtaceae, Solanaceae and Ulmaceae. The highest organic acid contents (as citric acid) were found in the preserves of Psidium guineense and Cyphomandra betaceae with the lowest in Sideroxylon obtusifolium and Myrciantes pungens. Total phenolics in the preserves ranged from 0.34 g kg−1 DM in Rhipsalis flocosa to 7.30 g kg−1 DM in Celtis iguanae. The MeOH‐solubles of the fruits/petioles as well as the preserves were assessed for inhibition of the enzyme xanthine oxidase (XO), decoloration of the free radical 2,2‐diphenyl‐1‐picryl‐hydrazyl (DPPH) and scavenging of the superoxide anion. The highest effect of the solubles towards the DPPH assay was observed for M pungens and Rubus imperialis before processing. None of the samples was effective as a XO inhibitor or superoxide anion scavenger. The best protein sources in our study were the fruits of Carica quercifolia, Celtis iguanae and Sambucus nigra. Copyright © 2005 Society of Chemical Industry
An efficient algorithm for modelling progressive damage accumulation in disordered materials
Authors: Nukala Phani Kumar V. V. , Šimunović Srđan , Guddati Murthy N.
Published: February 2005

This paper presents an efficient algorithm for the simulation of progressive fracture in disordered quasi‐brittle materials using discrete lattice networks. The main computational bottleneck involved in modelling the fracture simulations using large discrete lattice networks stems from the fact that a new large set of linear equations needs to be solved every time a lattice bond is broken. Using the present algorithm, the computational complexity of solving the new set of linear equations after breaking a bond reduces to a simple triangular solves (forward elimination and backward substitution) using the already Cholesky factored matrix. This algorithm using the direct sparse solver is faster than the Fourier accelerated iterative solvers such as the preconditioned conjugate gradient (PCG) solvers, and eliminates the critical slowing down associated with the iterative solvers that is especially severe close to the percolation critical points. Numerical results using random resistor networks for modelling the fracture and damage evolution in disordered materials substantiate the efficiency of the present algorithm. In particular, the proposed algorithm is especially advantageous for fracture simulations wherein ensemble averaging of numerical results is necessary to obtain a realistic lattice system response. Copyright © 2005 John Wiley & Sons, Ltd.
A new hybrid method for solving linear–non‐linear systems of equations
Authors: Lukasiewicz S. A. , Hojjati M. H.
Published: February 2005

This paper presents a new method for solving any combination of linear–non‐linear equations. The method is based on the separation of linear equations in terms of some selected variables from the non‐linear ones. The linear group is solved by means of any method suitable for the linear system. This operation needs no iteration. The non‐linear group, however, is solved by an iteration technique based on a new formula using the Taylor series expansion. The method has been described and demonstrated in several examples of analytical systems with very good results. The new method needs the initial approximations for non‐linear variables only. This requires far less computation than the Newton–Raphson method. The method also has a very good convergence rate. The proposed method is most beneficial for engineering systems that very often involve a large number of linear equations with limited number of non‐linear equations. Copyright © 2005 John Wiley & Sons, Ltd.
Treatment of discontinuity in the reproducing kernel element method
Authors: Lu Hongsheng , Wan Kim Do , Kam Liu Wing
Published: February 2005

A discontinuous reproducing kernel element approximation is proposed in the case where weak discontinuity exists over an interface in the physical domain. The proposed method can effectively take care of the discontinuity of the derivative by truncating the window function and global partition polynomials. This new approximation keeps the advantage of both finite element methods and meshfree methods as in the reproducing kernel element method. The approximation has the interpolation property if the support of the window function is contained in the union of the elements associated with the corresponding node; therefore, the continuity of the primitive variables at nodes on the interface is ensured. Furthermore, it is smooth on each subregion (or each material) separated by the interface. The major advantage of the method is its simplicity in implementation and it is computationally efficient compared to other methods treating discontinuity. The convergence of the numerical solution is validated through calculations of some material discontinuity problems. Copyright © 2005 John Wiley & Sons, Ltd.
A Crank‐Nicolson Petrov‐Galerkin method with quadrature for semi‐linear parabolic problems
Authors: Bialecki B. , Ganesh M. , Mustapha K.
Published: February 2005

We propose and analyze an application of a fully discrete C2 spline quadrature Petrov‐Galerkin method for spatial discretization of semi‐linear parabolic initial‐boundary value problems on rectangular domains. We prove second order in time and optimal order H1 norm convergence in space for the extrapolated Crank‐Nicolson quadrature Petrov‐Galerkin scheme. We demonstrate numerically both L2 and H1 norm optimal order convergence of the scheme even if the nonlinear source term is not smooth. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005.
The pseudo‐elastic response of rubberlike solids
Authors: Dorfmann A.
Published: February 2005

In this paper we focus on the mechanical behaviour of filled natural rubber. Filled elastomers under cyclic loading show noticeable differences between the mechanical response under loading and unloading during the first cycles in oscillation tests. We examine the change in material response associated with the Mullins effect and with cavitation, the latter arising from hydrostatic tensile stresses of sufficient magnitude. Then, we focus on constitutive equations using the theory of pseudoelasticity. Specifically, the strain‐energy function depends on a scalar parameter, which provides a means for modifying the form, thereby reflecting stress softening observed during unloading. The dissipation of energy is also accounted for by the use of a dissipation function, which evolves with the deformation history. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tests for the validation of numerical models for cracking of plain concrete
Authors: Feist Christian , Hofstetter Günter
Published: February 2005

The paper deals with experiments on single edge notched beams, subjected to 2D and 3D stress states, for the validation of material models for cracking of plain concrete. Both, the test setup and the test results, mainly consisting of load – displacement curves and crack paths and crack surfaces, are described briefly. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Messsystem zur Bestimmung der Kavitationsempfindlichkeit von Wasser
Authors: Heller W. , Kempe T.
Published: February 2005

Die Bedingungen für das Auftreten von Kavitation, d. h. das lokale Verdampfen der Flüssigkeit unter statischer oder dynamischer Zugbeanspruchung, sind eng verknüpft mit dem Zustand der Flüssigkeit hinsichtlich seiner “Zerreissfestigkeit”. Obwohl seit vielen Jahren der dominante Einfluss der Wasserqualität auf den Kavitationsbeginn bekannt ist, wird nach wie vor international dieser Parameter nicht gemessen. Sowohl bei der ASME/JASME Konferenzen in San Francisco 1999 [1] und Honolulu 2003 [2], als auch beim Fourth International Symposium on Cavitation in Pasadena 2001 [3] wurde deutlich, dass international vergleichbare Versuchsbedingungen bezüglich der Berücksichtigung der Wasserqualität geschaffen werden müssen. Eine relativ einfache Methode zur permanenten Messung der Zugspannung bzw. Kavitationsempfindlichkeit an Kavitationskanälen wurde in den letzten Monaten am ISM der TU Dresden konzipiert und gebaut. Diese Zugspannungsmesseinrichtung stellt nicht nur eine praktikable und kostengünstige Möglichkeit zur Messung dar, sondern sie kann mit relativ geringem Aufwand in alle bestehenden Kavitationskanäle eingebaut werden. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of the Material Parameters of a Micropolar Model for Granular Materials
Authors: Scholz Bernd , Ehlers Wolfgang
Published: February 2005

Granular frictional materials show a complex stress‐strain behaviour depending on the stress state and the load history. Furthermore, biaxial experiments exhibit the occurrence of shear band phenomena as the result of the localization of plastic strains. It is well known that the onset of shear bands is associated with microrotations of the granular microstructure, which has a significant influence on the macroscopic behaviour. Consequently, the macroscopic material must result in a micropolar model, which incorporates rotational degrees of freedom. After the formulation of the constitutive equations and the numerical implementation, it is necessary to determine all required material parameters. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Betrachtungen über zweieinhalbdimensionale Strömungen zäher Flüssigkeiten mit Gedächtnis
Authors: Böhme G. , Pokriefke G.
Published: February 2005

Bei der Durchströmung eines Kanals konstanten Querschnitts beliebiger Form stellt sich unter Wirkung eines axialen Druckgradienten und unter der Schleppwirkung bewegter Kanalwände eine räumliche Strömung mit kartesischen Geschwindigkeitskomponenten der Form u(x; y), v(x; y) und w(x; y) ein. Solche zweieinhalbdimensionalen Strömungsfelder besitzen nicht nur bei newtonschen Flüssigkeiten einige bemerkenswerte Eigenschaften, sondern unter gewissen Voraussetzungen auch bei Flüssigkeiten mit Gedächtnis. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Solution of Some Cardiovascular Problem
Authors: Prokop V. , Kozel K. , Keslerová R.
Published: February 2005

This paper deals with problem of numerical solution of flows through vessel with bypass. One could use model of Navier‐Stokes equations and find solution by using multistage Runge‐Kutta method together with time dependent artificial compressibility method. Some results of numerical solution of cardiovascular problems are presented: stationary and unstationary 2D flows in a vessel and a bypass. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation and characterization of polysiloxane–polyacrylates composite latices and their film properties
Authors: Zou Mingxuan , Huang Fangzhi , Nie Jun , Zhang Zhicheng , Ge Xuewu
Published: February 2005

Gamma‐ray induced seeded emulsion polymerization of methyl methacrylate and butyl acrylate was carried out in the presence of a polymerizable polysiloxane seed latex, obtained by ring‐opening copolymerization of octamethyl cyclotetrasiloxane (D4) and tetramethyl tetravinyl cyclotetrasiloxane (VD4), catalyzed by dodecylbenzene sulfonic acid (DBSA). A series of polysiloxane seed latices with different molecular weights, vinyl contents and particle sizes was used. The conversion–time curve showed that the polymerization rate was accelerated significantly by the seed latex. The obtained composite latices also showed good storage stability, mechanical stability and high electrolyte resistance ability. By using transmission electron microscopy (TEM), the morphology of the composite latex particles was found to display a quite uniform fine structure. The graft polymerization reactions between the polymerizable polysiloxane and the acrylates were confirmed by Fourier‐transform infrared spectroscopy (FT‐IR) and the graft efficiencies were also studied. The influence of seed content, molecular weight, vinyl content of the polysiloxane and seed latex particles size on the mechanical performance, water absorption ratio, surface properties and transparency of the latex films was also investigated. It was found that the seed content and particles size greatly affect the mechanical performance, water absorption ratio and transparency of the latex films. Copyright © 2005 Society of Chemical Industry
Surfactant concentration effects on amorphous PETG–montmorillonite layered silicate (MLS) nanocomposite films
Authors: Ranade Ajit , D'Souza Nandika , Thellen Christopher , Ratto Jo Ann
Published: February 2005

Improvements in the dispersion of montmorillonite layered silicates (MLS) have centered on appropriate surfactant treatment of the MLS, to ensure chemical interaction with the polymer material. Here, polyethylene terephthalate glycol (PETG) nanocomposites made with two MLS cation exchanged with dimethyl dihydrogenated tallow quaternary ammonium at two concentrations, 95 (MLS‐95) and 125 meq (100 g)−1 (MLS‐125), were investigated. The host MLS had a cation exchange capacity (CEC) around 92 meq (100 g)−1. The effect of exchanging past the CEC was studied with respect to the dispersion, glass transition and mechanical properties. Films were extruded on a single‐screw extruder with a film die attached. X‐ray diffraction (XRD) and optical transmission measurements indicated that increasing surfactant concentration changed the dispersion from intercalated to immiscible. The differences in the dispersion were related to the inherent degradation temperature of the MLS treated with the different surfactant concentrations, relative to the processing temperature. The over‐exchanged MLS (MLS‐125) suffered more surfactant degradation leading to an immiscible dispersion and narrower XRD peaks reflected a higher degree of ordering. In contrast, the XRD peaks of the MLS‐95 nanocomposites had increased breadth indicating decreased ordering. MLS orientation, however, did not influence birefringence measured by polarized Fourier‐transform infrared spectroscopy (FTIR). All nanocomposites showed no significant changes in the glass transition temperatures. Copyright © 2005 Society of Chemical Industry
Synergistic effect of nickel formate on the thermal and flame‐retardant properties of polypropylene
Authors: Chen Xuecheng , Ding Yaping , Tang Tao
Published: February 2005

Nickel formate was used as a catalyst to improve the flame‐retardancy of intumescent systems based on ammonium polyphosphate (APP) and pentaerythritol (petol) in polypropylene (PP). Limited oxygen index (LOI), X‐ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to characterize the fire‐retardancy and thermal stability of the PP system and the microstructure of the burned residue. The catalytic effect was shown in an increase in LOI, and a change in the residue microstructure and the thermal stability of the PP system. LOI increased with the concentration of the catalyst in the range 0.1–5 wt% of the composition until a maximum was reached. At higher concentration of the catalyst a decrease in the LOI was observed. Copyright © 2005 Society of Chemical Industry
Synthesis of polypropylene‐graft‐maleic anhydride compatibilizer and evaluation of nylon 6/polypropylene blend properties
Authors: Abacha N , Fellahi S
Published: February 2005

Polymer blends based on polyolefins are of a great interest owing to their broad spectrum of properties and practical applications. However, because of poor compatibilities of components, most of these systems generally exhibit high interfacial tension, a low degree of dispersion and poor mechanical properties. It is generally accepted that polypropylene (PP) and nylon 6 (N6) are not compatible and that their blending results in poor materials. The compatibility can be improved by the addition of a compatibilizer, and in this study PP was functionalized by maleic anhydride (MAH) in the presence of an optimized amount of dicumyl peroxide (DCP). The reaction was carried out in the molten state using an internal mixer. Then, once the compatibilizer polypropylene‐graft‐maleic anhydride (PP‐g‐MAH) was prepared, it was added at various concentrations (2.5–10 wt%) to 30/70 glass fibre reinforced N6 (GFRN6) PP, and the mechanical properties were evaluated. It was found that the incorporation of the compatibilizer enhanced the tensile properties (tensile strength and modulus) as well as the Izod impact properties of the notched samples. This was attributed to better interfacial adhesion as evidenced by scanning electron microscopy (SEM). The optimum in these properties was achieved at a critical PP‐g‐MAH concentration. Copyright © 2005 Society of Chemical Industry
Catalysis of aminolysis of p‐nitrophenyl acetate by 2‐pyridones
Authors: Fischer Christian B. , Steininger Harald , Stephenson David S. , Zipse Hendrik
Published: February 2005

The influence of a series of alkyl‐substituted 3‐cyano‐2‐pyridones on the kinetics of the reaction of p‐nitrophenyl acetate (10) with n‐butylamine (9) was studied. The reactions were monitored under pseudo‐first‐order conditions using an excess of n‐butylamine by 1H NMR spectroscopy at 23°C in CDCl3. A non‐linear dependence of the observed rate constants kobs on the pyridone concentration was observed in all cases. The results were analysed using two different kinetic models. The first model is based on the amine‐catalysed background reaction in combination with a pyridone‐catalysed process, whose efficiency is reduced through dimerization of the pyridone catalyst to an inactive dimer. The second model also involves the amine‐catalysed background process, now in combination with a catalysed process proceeding through pre‐equilibrium complexation of the substrate with a 1:1 amine–pyridone complex and a second (rate‐determining) step involving C—N bond formation. In addition to these kinetic studies, the aggregation behaviour of pyridones 2 and 3 was also studied in pure deuteriochloroform solutions and mixtures of n‐butylamine and deuteriochloroform. While substantial aggregation to dimers occurs for both pyridones in deuteriochloroform, no such dimerization appears to occur in deuteriochloroform solutions containing 250 × 10−3 mol l−1 n‐butylamine. This finding strongly supports kinetic model 2 as the more realistic choice. Copyright © 2005 John Wiley & Sons, Ltd.
Concentration effects in the cationic ring‐opening polymerization of 2‐ethyl‐2‐oxazoline in N,N‐dimethylacetamide
Authors: Hoogenboom Richard , Paulus Renzo M. , Fijten Martin W. M. , Schubert Ulrich S.
Published: February 2005

The monomer concentration for the cationic ring‐opening polymerization of 2‐ethyl‐2‐oxazoline in N,N‐dimethylacetamide was optimized utilizing high‐throughput experimentation methods. Detailed 1H‐NMR spectroscopic investigations were performed to understand the mechanistic aspects of the observed concentration effects. Finally, the improved polymerization concentration was applied for the synthesis of higher molecular weight (> 10,000 Da) poly(2‐ethyl‐2‐oxazoline)s. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1487–1497, 2005
Synthesis and optical and electrochemical properties of thermotropic, liquid‐crystalline, semirigid copolyesters based on 2,5‐diphenyl‐1,3,4‐thiadiazole units
Authors: Sato Moriyuki , Tada Yuji , Nakashima Shinji , Ishikura Ken‐ichi , Handa Makoto , Kasuga Kuninobu
Published: February 2005

Novel thermotropic liquid‐crystalline (LC) copolyesters were prepared with three disubstituted (4,4′‐, 3,4′‐, and 3,3′‐) dioxydiundecanol derivatives of terphenyl analogues of 1,3,4‐thiadiazole [2,5‐diphenyl‐1,3,4‐thiadiazole (DPTD)], and their optical and electrochemical properties were examined. Their structures were characterized with Fourier transform infrared, 1H NMR spectroscopy, and elemental analyses. The thermal and mesomorphic properties of the copolyesters were investigated with differential scanning calorimetry measurements, polarized microscopy observations, and X‐ray analyses; the data suggested that these copolymers formed LC smectic or nematic phases. The mesomorphic tendency decreased in the following order: 4,4′‐DPTD and 3,4′‐DPTD copolyesters > 4,4′‐DPTD and 3,3′‐DPTD copolyesters > 3,4′‐DPTD and 3,3′‐DPTD copolyesters. Solution and solid‐state ultraviolet–visible (UV–vis) and photoluminescence spectra indicated that the copolyesters displayed maximum absorbances and blue emissions according to the DPTD unit; the peak maxima of absorption and emission spectra of the copolyesters shifted to lower wavelengths in the aforementioned order for the LC properties. Cyclic voltammetry measurements indicated that the electrochemical band gaps of the polyesters estimated from the onset of reduction and oxidation processes were almost the same as the optical band gaps determined from the solid‐state UV–vis spectral data. The DPTD unit enhanced the hole‐injection barrier and improved the charge‐injection balance in these polyesters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1511–1525, 2005
Synthesis of regioregular poly(3‐octylthiophene)s via Suzuki polycondensation and end‐group analysis by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Jayakannan M. , Lou X. , van Dongen Joost L. J. , Janssen René A. J.
Published: February 2005

Regioregular poly(3‐octylthiophene)s were synthesized through a palladium‐catalyzed Suzuki polycondensation of 2‐(5‐iodo‐4‐octyl‐2‐thienyl)‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolane. The effects of the palladium catalyst {tetrakis(triphenylphosphine)palladium(0) [Pd(PPh3)4], palladium(II) acetate [Pd(OAc)2], [1, 1′‐bis(diphenylphosphino)ferrocene]dichloropalladium(II) [Pd(dppf)Cl2], tris(dibenzylideneacetone)dipalladium(0), or bis(triphenylphosphine)palladium(II) dichloride [Pd(PPh3)2Cl2]} and the reaction conditions (bases and solvents) were investigated. NMR spectroscopy revealed that poly(3‐octylthiophene)s prepared via this route were essentially regioregular. According to size exclusion chromatography, the highest molecular weights were obtained with in situ generated Pd(PPh3)4 and tetrakis(tri‐o‐tolylphosphine]palladium(0) {Pd[P(o‐Tol)3]4} catalysts or more reactive, phosphine‐free Pd(OAc)2. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry was used to analyze end groups and allowed the determination of some mechanistic aspects of the Suzuki polycondensation. The polymers were commonly terminated with hydrogen or iodine as a result of deboronation and some deiodination. Pd(PPh3)4, Pd(PPh3)2Cl2, and Pd[P(o‐Tol)3]4 induced aryl–aryl exchange reactions with the palladium center and resulted in some chains having phenyl‐ and o‐tolyl‐capped chain ends. Pd(dppf)Cl2 yielded only one type of chain, and it had hydrogen end groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1454–1462, 2005
Solid‐state polymerization of 2,3,6,7,10,11‐hexa(methacrylate) triphenylene
Authors: Yu Xiang , Chen Yangbin , Pan Caiyuan , Di Yan , Zhang Junying
Published: February 2005

A new monomer, 2,3,6,7,10,11‐hexa(methacrylate) triphenylene (HMTP), and its crystals have been successfully synthesized, and the solid‐state polymerization under UV irradiation has been investigated. The photo polymerization of HMTP in solid was confirmed by the reduction of vinyl bonds in the FT‐IR and UV spectra of PHMTP in comparison with the corresponding spectra of its precursor. Thus, IR spectroscope was used to follow the polymerization of HMTP crystals under UV irradiation, and kinetic studies show a first‐order reaction with rate constant of 6.12 × 10−3 min−1. This value is slightly larger than that measured by the weight method. The polarizing optical microscope and X‐ray diffraction were used to study the crystal structure difference between the polymers and its monomer. The results show that the polymers' crystals obtained from photo polymerization kept the monomer crystal lattice. Because of strong overlap between the π‐electron of the triphenylene, the monomer and polymer crystals showed different fluorescence properties. All these results proved that the photo polymerization of HMTP crystals is governed by the packing structure of monomer molecules; in other words, this reaction is just lattice controlled polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1526–1534, 2005
Impact of intraguild predation and lambda‐cyhalothrin on predation efficacy of three acarophagous predators
Authors: Provost Caroline , Coderre Daniel , Lucas Éric , Chouinard Gérald , Bostanian Noubar J
Published: February 2005

This laboratory study reports the interaction of three predators found in commercial apple orchards in Quebec, Hyaliodes vitripennis (Say) (Hemiptera: Miridae), Harmonia axyridis Pallas (Coleoptera: Coccinellidae) and Amblyseius fallacis (Garman) (Acarina: Phytoseiidae). First, intraguild predation between H vitripennis and the two other predators was characterized in the absence and presence of their extraguild prey, Tetranychus urticae Koch. The results showed an asymmetrical interaction in favour of the larger predator and the levels of intraguild predation were weak for the two predatory combinations. Presence of the phytophagous mite reduced the intensity of intraguild predation in the predatory combination of H axyridis and H vitripennis. Second, the effects of intraguild predation and the application of lambda‐cyhalothrin on predation efficacy of the predators were evaluated. The application of the insecticide reduced prey consumption of H vitripennis and H axyridis but did not affect that of A fallacis. Combination of predators and an insecticide application resulted in two different situations depending on the species involved: a reduced predation efficacy for the combination of H vitripennis and H axyridis due to a knockdown effect caused by the insecticide, and no effect on T urticae consumption for H vitripennis and A fallacis. It is suggested that an integrated pest management program based on H vitripennis, A fallacis and lambda‐cyhalothrin may be evaluated to repress phytophagous mites in Quebec orchards. Copyright © 2005 Society of Chemical Industry
Insecticide resistance inBemisia tabaci(Homoptera: Aleyrodidae) populations from Crete
Authors: Roditakis Emmanouil , Roditakis Nikos E , Tsagkarakou Anastasia
Published: February 2005

The resistance levels to α‐cypermethrin, bifenthrin, pirimiphos‐methyl, endosulfan and imidacloprid were determined inBemisia tabaci(Gennadius) from Crete. FiveB tabacipopulations collected from greenhouse and outdoor crops were bioassayed and compared with a reference susceptible strain.Bemisia tabacicollected in a floriculture greenhouse exhibited the highest resistance against all insecticides: at LC50, resistance factors were 23‐fold for bifenthrin, 80‐fold for α‐cypermethrin, 18‐fold for pirimiphos‐methyl, 58‐fold for endosulfan and 730‐fold for imidacloprid. A population collected on outdoor melons was more susceptible than the reference strain against all insecticides tested, suggesting the occurrence of local highly susceptibleB tabacipopulations in ‘refugia’. In pairwise comparisons of resistance levels, correlation was observed between the LC50values of the pyrethroid insecticides bifenthrin and α‐cypermethrin. Copyright © 2005 Society of Chemical Industry
The use of stainless steel in structures
Authors: Gardner Leroy
Published: February 2005

The past 15 years have seen the introduction or major revision of structural stainless steel design codes throughout the world, and at the same time, interest in the use of stainless steel in construction has been accelerating. Historically the high initial material cost of stainless steel has limited its use primarily to specialist and prestige applications. However, the emergence of design codes, a better awareness of the additional benefits of stainless steel and a transition towards sustainability are bringing more widespread use into conventional structures. Although a number of similarities between stainless steel and ordinary carbon steel exist, there is sufficient diversity in their physical properties to require separate treatment in structural design. In addition to the straightforward differences in basic material properties (such as Young's modulus and yield strength), further fundamental differences exist, such as the nature of the stress–strain curve and the material's response to cold‐work and elevated temperatures; these have implications at ultimate, serviceability and fire limit states. This paper describes the use of stainless steel as a structural material, discusses current structural design provisions, reviews recent research activities and highlights the important findings and developments.
Fabrication of AlGaN/GaN double‐insulator metal–oxide–semiconductor high‐electron‐mobility transistors using SiO2 and SiN as gate insulators
Authors: Balachander Krishnan , Arulkumaran Subramaniam , Sano Y. , Egawa Takashi , Baskar Krishnan
Published: February 2005

We report on the fabrication of AlGaN/GaN double‐insulator MOSHEMTs using SiO2 and SiN as the prime gate insulators. Both the dielectrics showed enhanced saturation current density and pinch‐off voltage compared to conventional HEMTs. The SiO2/SiN/AlGaN/GaN MOSHEMTs exhibited a low current collapse and low leakage current compared to SiN MISHEMTs and unpassivated HEMTs. However, the SiN/SiO2/AlGaN/GaN MOSHEMTs exhibited a lower current collapse coupled with moderate leakage current compared to SiO2 MOSHEMTs and unpassivated HEMTs. The comparison of device dc characteristics of double‐insulator MOSHEMTs with single‐insulator MOSHEMTs revealed its superiority in reducing the problem of current collapse and leakage current simultaneously. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simultaneous determination of paracetamol and dextropropoxyphene in human plasma by liquid chromatography/tandem mass spectrometry: application to clinical bioequivalence studies
Authors: Yin Ophelia Q. P. , Lam Sherry S. L. , Chow Moses S. S.
Published: February 2005

A liquid chromatography/mass spectrometry method for simultaneous determination of paracetamol and dextropropoxyphene in human plasma is described. Paracetamol and dextropropoxyphene, together with their internal standards (tolbutamide and pyrroliphene), were extracted from 0.5 mL of plasma using solid‐phase extraction. The chromatography was performed using a Thermo Hypersil APS‐2 Amino column (250 mm × 4.6 mm, 5 μm) with a mobile phase consisting of acetonitrile and 0.4% glacial acetic acid in water (20:80). The total run time was 6 min for each sample. The triple‐quadrupole mass spectrometer was operated in both positive (for detection of dextropropoxyphene and its IS pyrroliphene) and negative (for detection of paracetamol and its IS tolbutamide) modes using a polarity‐switching technique. Multiple reaction monitoring was used for quantification. The method was linear over the concentration range of 0.1–20 μg/mL for paracetamol and 0.5–80 ng/mL for dextropropoxyphene. The intra‐ and inter‐day precision were less than 10%, and the accuracy ranged from 92.2–110.9%. The lower limits of quantification were 0.1 μg/mL for paracetamol and 0.5 ng/mL for dextropropoxyphene. The present method provides a robust, fast and sensitive analytical tool for both paracetamol and dextropropoxyphene, and has been successfully applied to a clinical bioequivalence study in 14 subjects. Copyright © 2005 John Wiley & Sons, Ltd.
Resolution, quantification and confirmation of betamethasone and dexamethasone in equine plasma by liquid chromatography/tandem mass spectrometry
Authors: Luo Yi , Uboh Cornelius E. , Soma Lawrence R. , Guan Fuyu , Rudy Jeffrey A. , Tsang Deborah S.
Published: February 2005

This method describes the simultaneous separation, identification, quantification and confirmation of betamethasone (BTM) and dexamethasone (DXM) in equine plasma by liquid chromatography (LC) integrated with multidimensional tandem mass spectrometry. Analytes were directly extracted from equine plasma by methyltert‐butyl ether (MTBE). The residues were reconstituted with sample solvent. LC separation of the analytes was performed on a Hypercarb column using acetonitrile/water/formic acid (95:5:0.5, v/v/v) as the mobile phase. Sample screening, quantification and confirmation were performed in multiple reaction monitoring (MRM) mode. The method was linear over the concentration range of 0.1–75 ng/mL for both analytes. Limit of detection (LOD) was 50 pg/mL and that of quantification (LOQ) was 100 pg/mL for both analytes. The limit of confirmation (LOC) for the presence of BTM or DXM by MRM was 0.5 ng/mL. The intra‐and inter‐day precisions expressed as coefficient of variation (CV) for quantification of DXM and BTM from 0.1 to 50 ng/mL were less than 7% and the accuracy was in the range of 97–105%. This method is capable of distinguishing BTM from DXM when both analytes are simultaneously present in equine plasma. Measurement uncertainty for both analytes was estimated at less than 16%. The method is rapid, specific, selective, sensitive, simple and reliable. The importance of this method is its usefulness in directly identifying and differentiating BTM from DXM without derivatization. Copyright © 2005 John Wiley & Sons, Ltd.
Adjusting for observable selection bias in block randomized trials
Authors: Ivanova Anastasia , Barrier Robert C. , Berger Vance W.
Published: February 2005

In this paper, we propose a model‐based approach to detect and adjust for observable selection bias in a randomized clinical trial with two treatments and binary outcomes. The proposed method was evaluated using simulations of a randomized block design in which the investigator favoured the experimental treatment by attempting to enrol stronger patients (with greater probability of treatment success) if the probability of the next treatment being experimental was high, and enrol weak patients (with less probability of treatment success) if the probability of the next treatment being experimental was low. The method allows not only testing for the presence of observable selection bias, but also testing for a difference in treatment effects, adjusting for possible selection bias. Copyright © 2005 John Wiley & Sons, Ltd.
PIXE analysis of Chinese Ru celadon made in the 11–12th centuries
Authors: Zhang B. , Cheng H. S. , Zhao W. J. , Gao Z. Y. , Li G. X. , Xie J. Z. , Guo M. , Yang F. J.
Published: February 2005

The Ru kiln is one of the five most famous kilns (Ru, Guan, Ge, Ding and Jun kilns) in the Chinese Song Dynasty (AD 960–1279). The Ru Kuan kiln at Qingliang Temple, Henan Province, originated from the Ru folk kiln. PIXE and factor analysis were employed to study the difference between the folk celadon and the Kuan celadon. The relationship between the Ru Kuan and Ru folk celadons from the Qingliang Temple kiln site and the Ru celadon from the Zhanggongxiang kiln site, found in the last few years, was also studied. The experimental results showed that the same body raw material was used for the production of the Ru Kuan and Ru folk celadons whereas the Ru celadon from Zhanggongxiang was produced from a different body raw material. Factor analysis based on chemical components of the glaze is able to differentiate between the celadons, i.e. Ru Kuan celadon, Ru folk celadon and the Ru celadon from Zhanggongxiang. Copyright © 2005 John Wiley & Sons, Ltd.
Escape of photons and electrons from an HPGe detector at 81 keV
Authors: Yılmaz Ercan , Peköz Rengin , Can Cüneyt
Published: February 2005

Escape of Ge K x‐rays, Compton‐scattered incident radiation and photoelectrons from an HPGe detector was investigated for 81 keV incident photons. All three escape mechanisms were observed in the same experiment. Experimental escape fractions were compared with the results from Monte Carlo simulations. Good agreement was obtained for the escape of photons. However, the simulations underestimated the escape of photoelectrons. Copyright © 2005 John Wiley & Sons, Ltd.
Organic‐Inorganic Hybrids: Preparation and Structural Characterization of (Bu4N)2[Mo6O17(NAr)2] and (Bu4N)2[Mo6O18(NAr)] (Ar = o‐CH3C6H4)
Authors: Li Qiang , Wu Pingfan , Wei Yongge , Xia Yun , Wang Yuan , Guo Hongyou
Published: February 2005

In the presence of N, N′‐dicyclohexylcarbodiimide (DCC), (Bu4N)2[Mo6O18(NAr)] (1) and (Bu4N)2[Mo6O17(NAr)2] (2), Ar = o‐CH3C6H4, have been synthesized via the reaction of [α‐Mo8O26]4— with o‐toluidine. If the hydrochloride salt of o‐toluidine was added into the reactive mixture, only the monofunctionalized imido derivative of [Mo6O19]2— was obtained; the bifunctionalized derivative of [Mo6O19]2— was exclusively synthesized in the presence of non‐protonated o‐toluidine. The molecular and crystal structures of the hybrid compounds 1 and 2 were determined by X‐ray single crystal diffraction, and their UV, IR and NMR spectra were compared. Additionally, a possible reaction mechanism was proposed.
Bis(trifluoromethyl)mercury(II) Complexes with Purine and 3, 5‐Dimethyl‐4′‐amino‐triazole as Ligands, [Hg(CF3)2(Pur)]4 and [Hg(CF3)2(Dat)]2. Bis(trifluormethyl)quecksilber(II)‐Komplexe mit Purin und 3, 5‐Dimethyl‐4′‐amino‐triazol als Liganden: [Hg(CF3)2(Pur)]4 and [Hg(CF3)2(Dat)]2
Authors: Nockemann Peter , Schulz Frank , Naumann Dieter , Meyer Gerd
Published: February 2005

Colourless single crystals of [Hg(CF3)2(Pur)]4 and [Hg(CF3)2(Dat)]2 were obtained from aqueous and etheric solutions of the respective components Purine, (imidazo[4, 5‐d]pyrimidine, Pur), 3, 5‐dimethyl‐4′‐amino‐triazole (Dat) and bis(trifluoromethyl)mercury(II), Hg(CF3)2. [Hg(CF3)2(Pur)]4 crystallizes with the tetragonal system (P‐4, Z = 8, a = 1486.8(2), c = 1026.2(1) pm, Rall = 0.0657) with tetrameric molecules consisting of four purine molecules bridged by slightly bent Hg(CF3)2 molecules forming a cage with the CF3 ligands surrounding this cage. The two modifications of [Hg(Dat)(CF3)2]2 (I: 170 K, triclinic, P‐1, Z = 2, a = 814.9(2), b = 845.4(2), c = 968.4(3) pm, α = 106.55(2)°, β = 103.41(2)°, γ = 110.79(2)°, Rall = 0.1189; II: monoclinic, P21/c, Z = 8, a = 879.8(2), b = 1731.0(3), c = 1593.9(3) pm, β = 106.89(2)°, Rall= 0.1199) both contain dimeric molecules that are stacked parallel to one crystal axis to strands which are arranged in a parallel fashion in I and rotated against each other in II by 110°. In both, the tetrameric [Hg(CF3)2(Pur)]4 and the dimeric [Hg(CF3)2(Dat)]2 the Hg(CF3)2 molecules are slightly bent (around 167 and 170°) and rather weakly attached to the N‐donor ligands Pur and Dat with Hg‐N distances around 272 pm, although in both cases the Hg atoms bridge between two ligand molecules.
Structural Diversity of Sheets in Rubidium Uranyl Oxoselenates: Synthesis and Crystal Structures of Rb2[(UO2)(SeO4)2(H2O)](H2O), Rb2[(UO2)2(SeO4)3(H2O)2](H2O)4, and Rb4[(UO2)3(SeO4)5(H2O)]
Authors: Krivovichev Sergey V. , Kahlenberg Volker
Published: February 2005

Single crystals of three rubidium uranyl selenates, Rb2[(UO2)(SeO4)2(H2O)](H2O) (1), Rb2[(UO2)2(SeO4)3(H2O)2](H2O)4 (2), and Rb4[(UO2)3(SeO4)5(H2O)] (3), have been prepared by evaporation from aqueous solutions made out of mixtures of uranyl nitrate, selenic acid and Rb2CO3. The structures of all compounds have been solved by direct methods on the basis of X‐ray diffraction data sets. The crystallographic data are as follows: (1): orthorhombic, Pna21, a = 13.677(2), b = 11.8707(13), c = 7.6397(9) Å, V = 1240.4(3) Å3, R1 = 0.045 for 2396 independent observed reflections; (2): triclinic, P1¯, a = 8.4261(12), b = 11.8636(15), c = 13.3279(18) Å, α = 102.612(10), β = 107.250(10), γ = 102.510(10)°, V = 1183.7(3) Å3, R1 = 0.067 for 4762 independent observed reflections; (3): orthorhombic, Pbnm, a = 11.3761(14), b = 15.069(2), c = 19.2089(17) Å, V = 3292.9(7) Å3, R1 = 0.075 for 3808 independent observed reflections. The structures of the phases 1, 2, and 3 are based upon uranyl selenate hydrate sheets composed from corner‐sharing pentagonal [UO7]8— bipyramids and [SeO4]2— tetrahedra. In the crystal structure of 1, the sheets have composition [(UO2)(SeO4)2(H2O)]2— and run parallel to (001). The interlayer contains Rb+ cations and additional H2O molecules. In structure of 2, the [(UO2)2(SeO4)3(H2O)2]2— sheets are oriented parallel to (101). Highly disordered Rb+ cations and H2O molecules are located between the sheets. The structure of 3 is based upon [(UO2)3(SeO4)5(H2O)]4— sheets stacked parallel to (010) and contains Rb+ cations in the interlayers. The topologies of the uranyl oxoselenate sheets observed in the structures of 1, 2, and 3 are related to the same simple and highly‐symmetric graph consisting of 3‐connected white and 6‐connected black vertices.
Chemischer Transport fester Lösungen. 17 [1] Der Chemische Transport von ZnS und CdS mit Phosphor — die Mischphase ZnS:P
Authors: Locmelis S. , Milke E. , Binnewies M.
Published: February 2005

Chemical Vapor Transport of ZnS and CdS with Phosphorus — ZnS:P mixed Crystals

The volality of ZnS and CdS is enlarged in the presence of Phosphorus vapor. This is due to the formation of PS(g). By means of chemical vapor transport (1000 → 900 °C) using phosphorous as transport agent ZnS:P mixed crystals (sphalerit type) have been prepared. Density measurements on these mixed crystals show that interstitial zinc atoms are the consequence of the substitution of sulfur by phophorus atoms.
Synthesis and Structure Characterization of Metal‐organic Frameworks with a Triple Iron Helical Complex
Authors: Jian Fang‐Fang , Zhu Chong‐Yi , Xiao Hai‐Lian , Xu Liang‐Zhong
Published: February 2005

Metal‐organic frameworks were achieved from triple metal helical iron complex [(Fe2L3)·(H2O)4] (L = bis[2‐hydroxybenzaldehyde]hydrazonate). The phenyl rings of the helical units contact the neighbors via π‐π and C‐H···π interactions to form two‐dimensional channeled frameworks in which four solvent water molecules are included in the channels of the structure. Thermogravimetric analyses reveal that the solvent water molecules can be evacuated from the pores without loss of the framework periodicity. The crystal lattice is thermally stable up to 339.9 °C, and water can be re‐included by putting the heated material in water.
Metal Tetrahydroborates and Tetrahydroborato Metalates. 30 [1] Solvates of Alcoholato‐, Phenolato‐, and Bis(trimethylsilyl)amido‐Magnesium Tetrahydroborates XMgBH4(Ln). Metall Tetrahydroborate und Tetrahydroborato Metallate, 30 [1]. Solvate der Alkoholato‐, Phenolato‐ und Bis(trimethylsilyl)amino‐magnesium‐tetrahydroborate XMgBH4(Ln)
Authors: Bremer Mathias , Linti Gerald , Nöth Heinrich , Thomann‐Albach Martina , Wagner Gerhardt E. W. J.
Published: February 2005

A series of alcoholato and phenolato magnesium tetrahydroborates have been prepared as solvates (RO)Mg(BH4)(OEt2) by 1:1 reactions of ROH (R = Me, Et, iPr, tBu, CH2CMe3, Et2(tBu)C, Ph3C, Ph, 2, 4, 6‐Me3C6H2, (2, 6‐iPr)2C6H3, (2, 6‐tBu2)C6H3, 2‐(iPrO)C6H4, 2, 6‐(MeO)2C6H3) with diethyl ether solutions of EtMg(BH4). Displacement of diethyl ether by thf, dme, and diglyme produced various solvates (RO)Mg(BH4)(L)n (L = thf, dme, diglyme, n = 1, 2, 3). Most of these compounds are centrosymmetric dimers with a central Mg2O2 four membered ring. Irrespective of the composition, the 11B NMR signals are 1:4:6:4:1 quintets showing that the hydrogen atoms of the BH4 groups are magnetically equivalent. The molecular structure of eight compounds [(RO)Mg(BH4)(OEt2)]2 (R = iPr, tBu, tBuCH2, Et3C, Me3Si), [(PhO)Mg(BH4)(thf)2]2, (2, 6‐tBu2C6H3O)Mg(BH4)(thf)2, (2, 6‐tBu2C6H3O)‐Mg(BH4)(thf)(dme)) have been determined. Typical for all compounds are hexacoordinated Mg atoms. The mononuclear complexes feature bidentate BH4 groups while dinuclear species show di‐ or tridentate BH4 groups depending on the number of coordinated O atoms.

Mononuclear species are obtained only for compounds with bulky R groups, e. g. 2, 6‐(tBu2)(C6H3O)Mg(BH4)(thf)2 with tridentate BH4 groups. This compound has a linear O‐C‐Mg unit. In Me2SO the compound [(2‐iPrO)C6H4O]Mg(BH4)(OEt2) underwent ligand exchange to produce [(2‐iPrO)C6H4O]2Mg(OSMe2)]2.

Reaction of EtMgBH4 with a stoichiometric amount (1:1) of (Me3Si)2NH gives [((Me3Si)2N)‐Mg(BH4)(OEt2)]2, 46 with a tridentate BH4 group. Its diethyl ether molecule can be replaced by thf, dme and diglyme. Amongst these solvates the compound [(Me3Si)2N]Mg(BH4)(diglyme) is mononuclear and its structure shows a bidentate BH4 group. Compound 46 on repeated crystallization from diethyl ether is transformed into [(Me3SiO)Mg(BH4)(OEt2)]2.

No compound with a BH4 group bonded to two Mg atoms has so far been found.