bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Accurate CCSD(T) and DFT–SAPT Stabilization Energies of H‐Bonded and Stacked Structures of the Uracil Dimer
Authors: Pitoňák Michal , Riley Kevin E. , Neogrády Pavel , Hobza Pavel
Published: June 2008

The CCSD(T) interaction energies for the H‐bonded and stacked structures of the uracil dimer are determined at the aug‐cc‐pVDZ and aug‐cc‐pVTZ levels. On the basis of these calculations we can construct the CCSD(T) interaction energies at the complete basis set (CBS) limit. The most accurate energies, based either on direct extrapolation of the CCSD(T) correlation energies obtained with the aug‐cc‐pVDZ and aug‐cc‐pVTZ basis sets or on the sum of extrapolated MP2 interaction energies (from aug‐cc‐pVTZ and aug‐cc‐pVQZ basis sets) and extrapolated ΔCCSD(T) correction terms [difference between CCSD(T) and MP2 interaction energies] differ only slightly, which demonstrates the reliability and robustness of both techniques. The latter values, which represent new standards for the H‐bonding and stacking structures of the uracil dimer, differ from the previously published data for the S22 set by a small amount. This suggests that interaction energies of the S22 set are generated with chemical accuracy. The most accurate CCSD(T)/CBS interaction energies are compared with interaction energies obtained from various computational procedures, namely the SCS–MP2 (SCS: spin‐component‐scaled), SCS(MI)–MP2 (MI: molecular interaction), MP3, dispersion‐augmented DFT (DFT–D), M06–2X, and DFT–SAPT (SAPT: symmetry‐adapted perturbation theory) methods. Among these techniques, the best results are obtained with the SCS(MI)–MP2 method. Remarkably good binding energies are also obtained with the DFT–SAPT method. Both DFT techniques tested yield similarly good interaction energies. The large magnitude of the stacking energy for the uracil dimer, compared to that of the benzene dimer, is explained by attractive electrostatic interactions present in the stacked uracil dimer. These interactions force both subsystems to approach each other and the dispersion energy benefits from a shorter intersystem separation.
The Crucial Role of the K+–Aluminium Oxide Interaction in K+‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO2 Sorption at High Temperatures
Authors: Walspurger Stéphane , Boels Luciaan , Cobden Paul D. , Elzinga Gerard D. , Haije Wim G. , van den Brink Ruud W.
Published: June 2008

CO2‐free hydrogen can be produced from coal gasification power plants by pre‐combustion decarbonisation and carbon dioxide capture. Potassium carbonate promoted hydrotalcite‐based and alumina‐based materials are cheap and excellent materials for high‐temperature (300–500 °C) adsorption of CO2, and particularly promising in the sorption‐enhanced water gas shift (SEWGS) reaction. Alkaline promotion significantly improves CO2 reversible sorption capacity at 300–500 °C for both materials. Hydrotalcites and promoted hydrotalcites, promoted magnesium oxide and promoted γ‐alumina were investigated by in situ analytical methods (IR spectroscopy, sorption experiments, X‐ray diffraction) to identify structural and surface rearrangements. All experimental results show that potassium ions actually strongly interact with aluminium oxide centres in the aluminium‐containing materials. This study unambiguously shows that potassium promotion of aluminium oxide centres in hydrotalcite generates basic sites which reversibly adsorb CO2 at 400 °C.
A Property‐Matched Water‐Soluble Analogue of the Benchmark Ligand PPh3
Authors: Ferreira Michel , Bricout Hervé , Hapiot Frédéric , Sayede Adlane , Tilloy Sébastien , Monflier Eric
Published: June 2008

A series of sulfonated biphenylphosphanes were readily prepared from commercially available, inexpensive, and air‐stable organic compounds. Of these, the trisulfonated trisbiphenylphosphane can be considered as a true water‐soluble analogue of PPh3 as the cone angle and basicity of both phosphanes are very close and result in a similar coordination mode on palladium and rhodium complexes. The catalytic performance of the trisulfonated trisbiphenylphosphane was evaluated in the aqueous hydroformylation of 1‐decene and the Tsuji–Trost reaction.
Simultaneous Measurements of Ion Temperature by Segmented Tunnel and Katsumata Probe
Authors: Adámek J. , Kocan M. , Panek R. , Gunn J. P. , Martines E. , Stöckel J. , Ionita C. , Popa G. , Costin C. , Brotankova J. , Schrittwieser R. , Van Oost G.
Published: June 2008

Simultaneous measurements of the ion temperature by the segmented tunnel and Katsumata probe in the CASTOR tokamak are reported. The segmented tunnel probe measures two ion saturation currents Iseg 1, Iseg 2 towards two segments of the tunnel. The axis of the tunnel is aligned with the total magnetic field. The value of the ratio of these two currents combined with the results of the PIC modeling provides the ion temperature. Design and experimental arrangement of the Katsumata probe enable us to measure the pure ion current by sweeping the applied voltage. The ion temperature is then estimated from the exponential part of the measured I – V characteristic. Simultaneous measurements of the ion temperature by the segmented tunnel and Katsumata probe agree within a few eV. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Plasma Boundary in a Magnetic Field
Authors: Allen J. E.
Published: June 2008

Plasmas in the presence of a magnetic field can be divided into two categories, (a) those in which very small electron currents flow and the Boltzmann relation may be employed and (b) those in which there are appreciable electron currents and the use of the Boltzmann relation needs to be re‐examined. The present paper deals with the latter case. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computer Simulations of Probe Measurements in Argon Plasma: Effects of Finite Dimensions of the Probe
Authors: Bartoš P. , Hrach R. , Jelínek P.
Published: June 2008

Although the computer performance improves markedly in recent years, pure particle simulations of effects caused by finite probe dimensions can be still hardly performed. Therefore, the hybrid modelling technique combining the advantages of both fluid and particle modelling techniques seems to be the best alternative for these studies. In our work there are presented possibilities provided by the fast and well multitask‐able computer model of hybrid type, which has been developed at our departments. The behaviour of low‐temperature electropositive plasma in the vicinity of probes with frequently used geometry shapes (planar, cylindrical and spherical) is discussed. The work is aimed both on the effects of finite probe dimensions and on the influence of the probe holder on sheath formation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Displacement of Charge and Conduction Current in Collisionless Planar Sheaths During Voltage Transients
Authors: Braithwaite N. St. J. , LauroTaroni L. , Haas F. A. , Turner M. M.
Published: June 2008

The relaxation of a planar space charge sheath has been modelled numerically to elucidate the dynamics of the process. A numerical model has been used to show that ion dynamics need to be included if the space charge in the sheath exceeds the amount of charge stored in the external circuit. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Fluid Model of Recombination and Ionization for Deduction of Flow Velocity in Magnetized Plasmas
Authors: Chung K.‐S. , Woo H.‐J. , Choi Y.‐S. , Lee M.‐J.
Published: June 2008

For the analysis of atomic processes such as recombination and ionization in the divertor plasmas, a new fluid model on the ion collection to a probing object in magnetized plasma is developed including electron‐ion recombination, molecular activated recombination and ionization. Density profiles and ratio of ion saturation currents are presented with ionization and recombination for the application to the Mach probe. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiple Floating Potentials of an Electron Emitting Electrode that Terminates a Bounded Plasma System with Hot Electrons
Authors: Gyergyek T. , Čerček M. , Jurčič‐Zlobec B.
Published: June 2008

A fully kinetic one‐dimensional model of current collection by an electron emitting collector that limits a bounded plasma system that has been presented earlier [T. Gyergyek, M. Čerček, Czech J. Phys., 54, 431 (2004)] is further developed. Non‐zero drift velocities are included into the distribution functions of the hot and of the emitted electrons. Even relatively small drift velocities have large impact on the current collected by the collector. In the case of space charge limited electron emission from the collector the model predicts a triple floating potential of the collector for certain plasma parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Uniform Description of Errors in Measurement and Evaluation of Langmuir Probe Characteristics by Means of Apparatus Functions
Authors: Hannemann M.
Published: June 2008

The evaluation of Langmur probe measurements frequently has to deal with distortions of the probe current or its derivatives which occur e.g. in rf‐discharges or in the differentiation of probe characteristics with electrical or numerical techniques. Using different methods it was shown that the distorted current or derivative is given by the convolution of the desired true function with an apparatus function. This contribution summarizes the treatment of the problem based on the fact that all distortions are caused by the superposition of additional voltages to the steady probe bias. This uniform behaviour allows a uniform treatment. In contrast to literature here separate apparatus functions for distortions caused by rf‐ oscillations are obtained. Examples of apparatus functions are shown for all kinds of distortions. Some applications of apparatus functions and a measuring example are given and a modified evaluation of the probe characteristic at incomplete rf‐compensation is proposed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New Results on a Laser‐Heated Emissive Probe
Authors: Ionita C. , Balan P. , Windisch T. , Brandt C. , Grulke O. , Klinger T. , Schrittwieser R.
Published: June 2008

Direct measurements of the plasma potential with high temporal and spatial resolution are only possible with special probes whose floating potential becomes equal to the plasma potential. One of these probes is the emissive probe which can be heated to electron emission. This leads to the effect that the plasma electron current towards the probe is compensated by an equal electron emission current flowing from the probe into the plasma which shifts the probe floating potential to the value of the plasma potential. While emissive probes are usually realized by heatable loops of wires of a refractory metal like tungsten or thoriated tungsten, we have developed various types of probes whose tip can be heated by an infrared laser beam. This offers several advantages like higher emission, longer lifetime and faster time response. Here we report on the latest development of a laser‐heated emissive probe and on measurements with it in a magnetized helicon plasma. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Three Dimensional Structure of Turbulence in the WEGA Stellarator
Authors: Marsen S. , Otte M. , Wagner F.
Published: June 2008

Langmuir probes are used to study turbulent electrostatic fluctuations in the highly collisional plasmas of the WEGA stellarator. WEGA as a classical stellarator offers the opportunity to study fluctuations under various magnetic configurations. Two probe systems installed at WEGA give insight into the spatio‐temporal structure of fluctuations. A poloidal array of 13 probes is used to study the properties in poloidal direction. Toroidally resolved measurements give insight into the three‐dimensional structure of turbulence. To this end, a toroidally separated probe is placed on a field line intersecting the path of the poloidal array, as predicted by field line tracing calculations and verified experimentally by an electron gun. Probes are stationary biased to measure Isat and Φfl respectively. Fourier‐ and correlation‐analysis techniques are applied to the data. The paper gives a survey of the general characteristics of fluctuations in WEGA. The scaling of turbulent structures is studied by varying the ion mass and the magnetic field strength over a wide range and is found to depend on the drift parameter ρs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measurement of Plasma Properties of the Atmospheric Oxy‐Combustion Flame by Using Double Probe Method
Authors: Osaka Y. , Kobayashi N. , Ohno N. , Takamura S. , Tanaka Y. , Uesugi Y.
Published: June 2008

Oxy‐combustion generates a high‐temperature field of more than 3000 K and represents a nitrogen‐free process. In order to apply oxy‐combustion to next‐generation power plants and high‐temperature industrial technology this process has been enhanced by a new method, referred to as ‘plasma‐assisted combustion’. This method uses to control the oxy‐combustion flame with the radio‐frequency electromagnetic force acting on the hightemperature field of the oxy‐combustion flame. In order to establish the plasma‐assisted combustion technique it is necessary to assess the influence of the electromagnetic field on the flame parameters, i.e. to compare the main plasma properties (conductivity, electron density and temperature) of the oxy‐combustion flame with and without the assistance of the electromagnetic field. For that purpose we have developed a reciprocating double probe method to measure the plasma properties of the oxy‐combustion flame. In this paper we present (i) the experimental part (ii) the model that enables to estimate the electron temperature and density from the conductivity derived from the double probe measurements and (iii) measurements without the applied electromagnetic force. At the centre of the flame, the measured electrical conductivity is (1.3 ± 0.7) × 10–4 S/m which gives an electron temperature of 2800 ± 100 K and an electron density of (1.2 ± 0.5) × 1015 m–3. The electron temperature in oxy‐combustion is equivalent to the adiabatic flame temperature. The equilibrium adiabatic flame temperature in the oxy‐combustion of methane is estimated to be approximately 3100 K, which is in good agreement with the electron temperature measured in this study. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of a Fast Electron Component on the Plasma Sheath Structure at the Inside of the Tunnel Probe
Authors: Rompuy T. Van , Gunn J. P. , Oost G. Van
Published: June 2008

The possible influence of a small population of suprathermal electrons on the tunnel probe, a new kind of Langmuir probe for fast DC measurements of ion flux and electron temperature in the tokamak scrape‐off layer, has been investigated by numerical simulations. It was found that suprathermal electrons can influence the ion current distribution over the inner plasma collecting surfaces of the tunnel probe, and thus influence tunnel probe Te measurements. The ion current distribution depends on the structure of the Debye and the magnetic sheath inside the tunnel probe. Therefore, we make here a first attempt at investigating the influence of suprathermal electrons on the scaling of those sheaths. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ion‐Neutral Collision Effects in Langmuir Probe Theory
Authors: Taccogna F. , Longo S. , Capitelli M.
Published: June 2008

In weakly collisional sheaths, potential wells and barriers could appear. These can cause the presence of repulsed and trapped ions in the region surrounding a negatively biased Langmuir probe, invalidating the orbital motion limited (OML) theory. In this work, a Particle‐In‐Cell/Test‐Particle Monte Carlo (PIC/TPMC) model of Ar plasma at medium gas pressure has been developed in order to show the effect of ion‐neutral collisions. In fact, the results of the present simulation for different discharge pressures demonstrate the complex structure of electric potential around the probe and the failure of analytical theories. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deposition of BaxSr1–xTiO3 thin Films by Double RF Hollow Cathode Plasma Jet System
Authors: Hubička Z. , Virostko P. , Tichý M. , Čada M. , Adámek P. , Olejníček J. , Deyneka A. , Churpita O. , Valvoda V. , Jastrabík L.
Published: June 2008

Low‐pressure plasma jet system with two hollow cathodes was used for deposition of Bax Sr1–x TiO3 (BSTO) ferroelectric thin films. Two RF hollow cathode plasma jet guns were pointed to the substrate where BSTO thin films were deposited. High density RF hollow cathode discharge was generated in ceramic nozzles made of SrTiO3 (STO) and BaTiO3 (BTO). Pulse modulated RF power was applied on water‐cooled copper block insulated from the plasma by ceramic and grounded stainless steel shield. In the experiment, the composition of BSTO films was controlled by magnitude of average RF power applied on particular plasma jet guns with STO and BTO nozzles. By this method, BSTO films were deposited on single crystal silicon substrate and on Pt top of Pt/TiO2/SiO2/Si multi‐layer system. X‐ray diffraction proved that BSTO thin films were polycrystalline with perovskite structure and measurement of dielectric properties showed ferroelectric hysteresis loop at room temperature. Time resolved Langmuir probe system and plasma impedance monitor were used for in situ plasma diagnostics and control of deposition conditions. Furthermore, plasma jets were analyzed during the deposition process by spatially resolved optical emission spectroscopy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the Langmuir Probe Shaft on Measuring Plasma Parameters
Authors: Waldmann O. , Fussmann G.
Published: June 2008

Because of their good spatial and temporal resolution Langmuir probes are often used for plasma diagnostics. One has to keep in mind, however, that the presence of the probe can substantially perturb the neighboring plasma.

Apart from the probe tip, in particular the probe shaft may affect the measured values of temperature and density. We have studied this latter effect at the linear plasma generator PSI‐2 which provides a stationary plasma column of 2.6 m in length and 8 cm in diameter.

Two single probes differently arranged were used in these experiments. In the first case the probes were in the same plane but tilted to each other in azimuthal direction. In the second arrangement the probes were separated by a distance along the magnetic field lines at the same azimuthal angle. One probe was kept at a fixed (but variable) position while the other was scanning the plasma radially.

It is found that the electron temperature is hardly influenced by the presence of the second probe, but the electron density is decreased up to 30%. The results can approximately be described in the frame of a global particle model treating the probe shafts as additional plasma sinks. Most striking is the observation that large global reductions of the density are accompanied by only moderate local changes. This means that the perturbations caused by the probe are characterized by a large scale effect, possibly indicating anomalous diffusion. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kalman filter‐based channel estimation and ICI suppression for high‐mobility OFDM systems
Authors: Gupta Prerana , Mehra D. K.
Published: June 2008

The use of orthogonal frequency division multiplexing (OFDM) in frequency‐selective fading environments has been well explored. However, OFDM is more prone to time‐selective fading compared with single‐carrier systems. Rapid time variations destroy the subcarrier orthogonality and introduce inter‐carrier interference (ICI). Besides this, obtaining reliable channel estimates for receiver equalization is a non‐trivial task in rapidly fading systems. Our work addresses the problem of channel estimation and ICI suppression by viewing the system as a state‐space model. The Kalman filter is employed to estimate the channel; this is followed by a time‐domain ICI mitigation filter that maximizes the signal‐to‐interference plus noise ratio (SINR) at the receiver. This method is seen to provide good estimation performance apart from significant SINR gain with low training overhead. Suitable bounds on the performance of the system are described; bit error rate (BER) performance over a time‐invariant Rayleigh fading channel serves as the lower bound, whereas BER performance over a doubly selective system with ICI as the dominant impairment provides the upper bound. Copyright © 2008 John Wiley & Sons, Ltd.
Chaotic communication systems in the presence of parametric uncertainty and mismatch
Authors: Ji Yuan , Wen Changyun , Li Zheng Guo
Published: June 2008

A recently developed synchronization scheme in (Phys. Lett. A 2007; 361:108–114) is applied to design a secure communication system with parametric uncertainties and mismatches in this paper. Based on the bounds of the uncertainties and mismatches and a pre‐specified bound of the synchronization error, a scheme is given to determine an upper bound of impulsive intervals. With the scheme, the synchronization error is ensured to approach to and stay within the given pre‐specified bound and this in turn guarantees that signals can be decoded accurately. To further enhance system security, it is also proposed to transmit functions of the chaotic states at impulsive instants, instead of the states directly. The designed system is tested and verified with text, audio and image encryption and transmission with comparisons to some existing schemes. Copyright © 2008 John Wiley & Sons, Ltd.
Stereoselective Synthesis of the Naturally Occurring 2‐Pyranone Dodoneine
Authors: Álvarez‐Bercedo Paula , Falomir Eva , Murga Juan , Carda Miguel , Marco J. Alberto
Published: June 2008

The first total synthesis of the naturally occurring dihydropyranone dodoneine is reported. Asymmetric allylation reactions were used for the stereoselective generation of the two stereogenic centers. The pyranone ring was created by ring‐closing metathesis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Room‐Temperature Electrophilic 5‐endo‐dig Chlorocyclization of Alk‐3‐yn‐1‐ones with the Use of Pool Sanitizer: Synthesis of 3‐Chlorofurans and 5‐Chlorofuropyrimidine Nucleosides (Eur. J. Org. Chem. 20/2008)
Authors: Sniady Adam , Morreale Marco S. , Wheeler Kraig A. , Dembinski Roman
Published: June 2008

The cover picture shows an artistic image related to the chlorocyclization reaction with the use of trichloro‐s‐triazinetrione, which is sold as a chemical for pools. This reagent is a source of electrophilic chlorine that triggers a tandem chlorination/cylization reaction that yields 3‐chlorofurans or 5‐chlorofuropyrimidine nucleosides. Details are discussed in the Short Communication by R. Dembinski et al. on p. 3449 ff. Cover art by Tomasz Sniady.
Highly sensitive double‐fluorescent dye staining on microchip electrophoresis for analysis of milk proteins
Authors: Okada Hiroki , Kaji Noritada , Tokeshi Manabu , Baba Yoshinobu
Published: June 2008

We demonstrated a highly sensitive double‐fluorescent dye staining in microchip electrophoresis (ME) for analysis of milk proteins. The detection sensitivity of ME was very limited so far and needed improvement. Our staining method consisted of two steps. First, in sample preparation before electrophoresis, protein was covalently bound to an amine‐reactive fluorescent dye, Cy5. Then, the Cy5‐attached protein was denatured with SDS and was further stained, during electrophoresis, with Agilent fluorescent dye, which was noncovalently attached to hydrophobic regions of the SDS‐protein complexes. This double‐fluorescent staining enhanced fluorescent intensity and lowered the detection limit to 200 pg of protein. This provided higher sensitivity than silver‐ or SYPRO Ruby‐staining methods, which have previously given the highest sensitivity in protein staining. In addition, we applied our staining method to analysis of milk proteins and achieved their successful detection, whereas it was difficult to analyze them by the unimproved method.
Recent advances in the analysis of biological particles by capillary electrophoresis
Authors: Kostal Vratislav , Arriaga Edgar A.
Published: June 2008

This review covers research papers published in the years 2005–2007 that describe the application of capillary electrophoresis to the analysis of biological particles such as whole cells, subcellular organelles, viruses and microorganisms.
The synthesis and structures of deuterium‐labeled 5‐substituted 1H‐tetrazoles
Authors: Zhao Hong
Published: June 2008

The synthesis and crystal structures of deuterium‐labeled 5‐substituted 1H‐tetrazoles, 5‐[2H5]phenyl‐1H‐tetrazole (I), 5‐[2H7]tolyl‐1H‐tetrazole (II), and 5‐[2H7]benzyl‐1H‐tetrazole (III) are reported. All syntheses were carried out using simple, facile steps and the products were obtained in high yields. Copyright © 2008 John Wiley & Sons, Ltd.
Mechanical Reinforcement of a Supramolecular Hydrogel Comprising an Artificial Glyco‐Lipid through Supramolecular Copolymerization
Authors: Ikeda Masato , Shimizu Yusuke , Matsumoto Shinji , Komatsu Harunobu , Tamaru Shun‐ichi , Takigawa Toshikazu , Hamachi Itaru
Published: June 2008

Supramolecular copolymer hydrogels were prepared by mixing 1 and the additives 2–8, and their rheological properties were evaluated. It was found that additive 3 reinforced the mechanical strength of the resultant hydrogel most efficiently, increasing the yield stress of SCH 1+3 about fourfold. The optimal mixing between the glyco‐lipid hydrogelator 1 and the additive 3 sufficiently enhanced the mechanical strength of the resultant SCH, which improved the handling of the SH on the large scale. These results indicate that supramolecular copolymerization can provide the supramolecular hydrogel with desired properties and/or functions.

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A Combined Analysis of PVT and Rheological Measurements: Novel Results for Three Amorphous Polymers
Authors: Fernández Mercedes , Muñoz María Eugenia , Santamaría Anton
Published: June 2008

The fractional free volume f of polycarbonate (PC), polystyrene (PS) and poly(methyl methacrylate) (PMMA) is determined by pressure–volume–temperature (PVT) measurements using the Simha–Somcynsky equation of state. Results are compared with the free volume obtained by viscoelastic measurements. Temperature and pressure dependent viscosity and free volume results are correlated using the characteristic ratio C∞ and the parameter B of the monomeric friction factor ζ = ζexp B/f. This leads to obtain new results on the temperature and pressure dependence of C∞, as well as on the pressure dependence of B parameter.

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Facile Synthesis and Characterization of Novel Capsicum‐Like Polyphosphazene Nanotubes via an in situ Template Route
Authors: Fu Jianwei , Huang Xiaobin , Zhu Yan , Zhu Lu , Tang Xiaozhen
Published: June 2008

Novel polyphosphazene nanotubes with closed ends were prepared by polycondensation of HCCP and BPS via an in situ template approach at room temperature. The nanotubes were characterized by FT‐IR and NMR spectroscopy and elemental analysis. Their cross‐linked structures were confirmed. SEM and TEM indicated that they resemble capsicum, with a length of 2–6 µm, and the outer diameters of the two ends were about 200–500 and 100 nm. The majority of nanotubes had inner diameters of about 30–50 nm. The tube ends were closed. TGA analysis showed that their decomposition started at 468 °C. A formation mechanism of the capsicum‐like nanotubes is proposed.

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Construction of Linear Polymers, Dendrimers, Networks, and Other Polymeric Architectures by Copper‐Catalyzed Azide‐Alkyne Cycloaddition “Click” Chemistry
Authors: Johnson Jeremiah A. , Finn M. G. , Koberstein Jeffrey T. , Turro Nicholas J.
Published: June 2008

The enrichment of materials synthesis with the diverse chemical building blocks and functional groups of small molecule organic chemistry has been greatly accelerated in recent years by the introduction of the copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). The efficiency and modular nature of this unique reaction enables materials chemists to prepare novel functional materials of unprecedented complexity. This review summarizes the application of CuAAC to the field of materials construction, defined here as the preparation of materials with architectural integrity dependent upon the triazole linkage. Recent examples, including linear polymers, dendrimers, polymer networks, polymeric nanoparticles, and other polymeric architectures, are described.

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Cationic and Anionic Conjugated Polyelectrolytes: Aggregation‐Mediated Fluorescence Energy Transfer to Dye‐Labeled DNA
Authors: Jin Youngeup , Yang Renquiang , Suh Hongsuk , Woo Han Young
Published: June 2008

An electrostatic complex of water‐soluble conjugated polyelectrolytes (CPs) between anionic poly(9,9‐bis(4′‐sulfonatobutyl)fluorene‐co‐alt‐1,4‐phenylene) disodium salt (a‐PFP) and cationic poly(9,9‐bis((6′‐N,N,N,‐trimethylammonium)hexyl)fluorene‐co‐2,1,3‐bezothiadiazole) dibromide (85:15) (c‐PFB15) was tested as a fluorescence resonance energy transfer (FRET) donor to Texas Red (TR)‐labeled single‐stranded DNA (ssDNA‐TR) via two‐step FRET processes. Electrostatic complexation of a‐PFP and c‐PFB15 in water leads to aggregation of polymer chains, a concomitant reduction of intersegment distances, and energy transfer to the benzothiadiazole (BT) segments. The following complexation with ssDNA‐TR leads to energy transfer from BT to TR via two‐step FRET processes. This detection schematic shows an FRET‐induced signal amplification, which can be achieved by adjusting the charge ratio in the cationic/anionic CP complex and controlling the number density of the binding CPs around the acceptor, resulting in enhanced antenna effects and sensitivity in CP‐based FRET DNA detection assays.

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Synthesis of a Multi Alternating‐Arm‐Containing Dendritic Star Copolymer by RAFT and Cationic Ring‐Opening Polymerization
Authors: Zhong Ling , Zhou Yongfeng , Yan Deyue , Pan Caiyuan
Published: June 2008

A new dendritic heteroarm star copolymer that contains multi‐alternating arms of poly(ethylene oxide‐tetrahydrofuran) (P(EO‐THF)) and poly(methyl methacrylate) (PMMA) on a dendritic polyester core has been synthesized by a ‘core‐first’ approach by combination of sequential cationic ring‐opening polymerization (CROP) and reversible addition–fragmentation transfer (RAFT) polymerization initiated by a dendritic macroinitiator (3) capped with multi‐alternating terminal carboxylic acid groups (used directly to initiate the ROP of THF in the presence of EO as a polymerization promoter to attain P(EO‐THF) arms) and dithiobenzoate groups (used to initiate RAFT polymerization of MMA to attain PMMA arms). The structures of the products were confirmed by NMR spectroscopy, GPC‐MALLS, and DSC measurements.

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On the stabilization of the Timoshenko system by a weak nonlinear dissipation
Authors: Messaoudi Salim A. , Mustafa Muhammad I.
Published: June 2008

In this paper we consider the following Timoshenko‐type system:

Without imposing any restrictive growth assumption on g at the origin, we establish a general decay result depending on g and α. Copyright © 2008 John Wiley & Sons, Ltd.
Penalty finite element approximations for the Stokes equations by L2 projection
Authors: Li Jian
Published: June 2008

This paper considers the penalty finite element method for the Stokes equations, based on some stable finite elements space pair (Xh, Mh) that do satisfy the discrete inf–sup condition. Theoretical results show that the penalty error converges as fast as one should expect from the order of the elements. Moreover, the penalty finite element method by L2 projection can improve the penalty error estimates. Finally, we confirm these results by a series of numerical experiments. Copyright © 2008 John Wiley & Sons, Ltd.
Charged relativistic spheres with generalized potentials
Authors: Thirukkanesh S. , Maharaj S. D.
Published: June 2008

A new class of exact solutions of the Einstein–Maxwell system is found in closed form. This is achieved by choosing a generalized form for one of the gravitational potentials and a particular form for the electric field intensity. For specific values of the parameters it is possible to write the new series solutions in terms of elementary functions. We regain well‐known physically reasonable models. A physical analysis indicates that the model may be used to describe a charged sphere. The influence of the electromagnetic field on the gravitational interaction is highlighted. Copyright © 2008 John Wiley & Sons, Ltd.
Complete NMR data assignments for novel pterocarpans from Harpalyce brasiliana
Authors: Araújo Renata Mendonça , Pinheiro Sávio Moita , Lima Mary Anne Sousa , Silveira Edilberto Rocha
Published: June 2008

A NMR study of two new pterocarpans isolated from the roots of Harpalyce brasiliana is described. In addition to 1D NMR, 2D shift‐correlated NMR pulse sequences (1H1H‐COSY, HSQC and HMBC) were used to establish the structures, and unambiguously perform the 1H and 13C chemical shift assignments. Copyright © 2008 John Wiley & Sons, Ltd.
Continuous Miniemulsion Polymerization
Authors: Schork F. Joseph , Guo Juchen
Published: June 2008

Most miniemulsion polymerizations are carried out in batch reactors. However, continuous reactors or continuous reactor trains can provide a high level of consistency when operated at steady state. In this feature article, progress in continuous miniemulsion polymerization will be reviewed. Special attention will be given to issues of monomer diffusion and secondary nucleation. A large portion of the paper will be devoted to controlled radical polymerization for two reasons. First, this is a relatively new field, particularly when continuous reactors are considered, and second, for controlled radical polymerization in continuous reactors, the molecular weight distribution of the product is a direct function of the reactor residence time distribution.

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Short‐scan‐time multi‐slice diffusion MRI of the mouse cervical spinal cord using echo planar imaging
Authors: Callot Virginie , Duhamel Guillaume , Cozzone Patrick J. , Kober Frank
Published: June 2008

Mouse spinal cord (SC) diffusion‐weighted imaging (DWI) provides important information on tissue morphology and structural changes that may occur during pathologies such as multiple sclerosis or SC injury. The acquisition scheme of the commonly used DWI techniques is based on conventional spin‐echo encoding, which is time‐consuming. The purpose of this work was to investigate whether the use of echo planar imaging (EPI) would provide good‐quality diffusion MR images of mouse SC, as well as accurate measurements of diffusion‐derived metrics, and thus enable diffusion tensor imaging (DTI) and highly resolved DWI within reasonable scan times. A four‐shot diffusion‐weighted spin‐echo EPI (SE‐EPI) sequence was evaluated at 11.75 T on a group of healthy mice (n = 10). SE‐EPI‐derived apparent diffusion coefficients of gray and white matter were compared with those obtained using a conventional spin‐echo sequence (c‐SE) to validate the accuracy of the method. To take advantage of the reduction in acquisition time offered by the EPI sequence, multi‐slice DTI acquisitions were performed covering the cervical segments (six slices, six diffusion‐encoding directions, three b values) within 30 min (vs 2 h for c‐SE). From these measurements, fractional anisotropy and mean diffusivities were calculated, and fiber tracking along the C1 to C6 cervical segments was performed. In addition, high‐resolution images (74 × 94 µm2) were acquired within 5 min per direction. Clear delineation of gray and white matter and identical apparent diffusion coefficient values were obtained, with a threefold reduction in acquisition time compared with c‐SE. While overcoming the difficulties associated with high spatially and temporally resolved DTI measurements, the present SE‐EPI approach permitted identification of reliable quantitative parameters with a reproducibility compatible with the detection of pathologies. The SE‐EPI method may be particularly valuable when multiple sets of images from the SC are needed, in cases of rapidly evolving conditions, to decrease the duration of anesthesia or to improve MR exploration by including additional MR measurements. Copyright © 2008 John Wiley & Sons, Ltd.
Three‐dimensional water diffusion in impermeable cylindrical tubes: theory versus experiments
Authors: Avram Liat , Özarslan Evren , Assaf Yaniv , Bar‐Shir Amnon , Cohen Yoram , Basser Peter J.
Published: June 2008

Characterizing diffusion of gases and liquids within pores is important in understanding numerous transport processes and affects a wide range of practical applications. Previous measurements of the pulsed gradient stimulated echo (PGSTE) signal attenuation, E(q), of water within nerves and impermeable cylindrical microcapillary tubes showed it to be exquisitely sensitive to the orientation of the applied wave vector, q, with respect to the tube axis in the high‐q regime. Here, we provide a simple three‐dimensional model to explain this angular dependence by decomposing the average propagator, which describes the net displacement of water molecules, into components parallel and perpendicular to the tube wall, in which axial diffusion is free and radial diffusion is restricted. The model faithfully predicts the experimental data, not only the observed diffraction peaks in E(q) when the diffusion gradients are approximately normal to the tube wall, but their sudden disappearance when the gradient orientation possesses a small axial component. The model also successfully predicts the dependence of E(q) on gradient pulse duration and on gradient strength as well as tube inner diameter. To account for the deviation from the narrow pulse approximation in the PGSTE sequence, we use Callaghan's matrix operator framework, which this study validates experimentally for the first time. We also show how to combine average propagators derived for classical one‐dimensional and two‐dimensional models of restricted diffusion (e.g. between plates, within cylinders) to construct composite three‐dimensional models of diffusion in complex media containing pores (e.g. rectangular prisms and/or capped cylinders) having a distribution of orientations, sizes, and aspect ratios. This three‐dimensional modeling framework should aid in describing diffusion in numerous biological systems and in a myriad of materials sciences applications. Copyright © 2008 John Wiley & Sons, Ltd.
Mechanical characteristics of hydrogenated natural rubber vulcanizates
Authors: Ikeda Yuko , Phinyocheep Pranee , Kittipoom Sumet , Ruancharoen Jareerat , Kokubo Yota , Morita Yuichi , Hijikata Kensuke , Kohjiya Shinzo
Published: June 2008

Mechanical properties of partially hydrogenated natural rubber (HNR) vulcanizates were evaluated regarding their chemical structure and crystallizable nature of HNR, and are reported here, to the best of our knowledge, for the first time. HNRs of three levels of hydrogenation (20.6, 29.0, and 40.6 mol%) were successfully prepared by the chemical modification of natural rubber (NR) latex using N2H4 and H2O2 as reagents, in a sufficient amount for preparing sulfur‐crosslinked samples to be subjected to mechanical and structural measurements. The three HNR vulcanizates were found to be crystallizable upon stretching; it is noted that even 40.6 mol% hydrogenation did not prevent HNR vulcanizates from crystallization upon stretching, while their onset strain of crystallization was higher than that of NR vulcanizate. The hysteresis loss and residual strain up to a stretching ratio of 2 for the HNR vulcanizates tended to become larger with the increase in the degree of the hydrogenation. Tensile and dynamic mechanical properties of 20.6 mol% hydrogenated HNR vulcanizate were comparable to those of NR vulcanizate. From differential scanning calorimetry and temperature dispersion of dynamic modulus or loss, the glass transition temperatures of HNR vulcanizates were found to be almost the same as that of NR vulcanizate, which is also notable. The thermal stability of HNR vulcanizates was better than that of NR vulcanizate. Thus, this chemical modification seems to give a promising NR derivative whose properties can be equivalent or even better than the mother polymer. Copyright © 2008 John Wiley & Sons, Ltd.
Curing kinetics of the epoxy system diglycidyl ether of bisphenol A/isophoronediamine by Fourier transform infrared spectroscopy
Authors: Fraga Francisco , Vazquez Eva C. , Rodríguez‐Núñez Eugenio , Martínez‐Ageitos José Manuel
Published: June 2008

The curing reaction of an epoxy system consisting of a diglycidyl ether of bisphenol A (BADGE, n = 0) and isophoronediamine (IPD), was studied by Fourier transform infrared spectroscopy (FTIR). The degree of conversions and the reaction rates at different isothermal curing temperatures were calculated from the infrared spectra using a method derived from Beer's law. This method is based on the ratio of the height of the characteristic absorbance peak to reference absorbance peak. A kinetic model proposed by Sourour and Kamal has been used to fit experimental data. Copyright © 2008 John Wiley & Sons, Ltd.
α1‐Adrenozeptor‐Antagonisten. Bei BPS und Hypertonie
Authors: Haubold  , Hein Lutz
Published: June 2008

α1‐Antagonisten sind sehr wirksame Pharmaka für die Kombinationstherapie der Hypertonie sowie für die symptomatische Behandlung des benignen Prostatasyndroms. Weitere klinische und klinisch‐experimentelle Untersuchungen sind nötig, um zum einen den Mechanismus und exakten Wirkort dieser Arzneistoffe beim Prostatasyndrom aufzuklären. Zum anderen werden neu entwickelte Substanzen zeigen müssen, ob sich aus der Selektivität für einen oder zwei Rezeptorsubtypen ein klinischer Vorteil ergibt.
Arterielle Hypertonie – was gibt es Neues? Therapie einer Volkskrankheit
Authors: Fiedler Martin
Published: June 2008

Die arterielle Hypertonie ist eine Volkskrankheit. Trotz Verbesserung der Versorgungssituation ist die Dunkelziffer nicht erkannter Hypertoniker in Deutschland noch zu hoch und die Implementierung aktueller Leitlinien in die Diagnostik und Therapie der Patienten unbefriedigend. Die aktuellen Leitlinien der DHL 2005 und ESH/ESC 2007 sehen als Grundlage der Therapiestrategie nicht allein die exakt ermittelte Höhe des Blutdrucks, sondern fokussieren vielmehr auf die Beurteilung des individuellen kardiovaskulären Gesamtrisikos der Patienten. Daher spielt die exakte Erfassung von zusätzlichen kardiovaskulären Risikofaktoren, hypertensiven Endorganschäden und Begleiterkrankungen eine ganz entscheidende Rolle. In den ESH/ESC‐Leitlinien 2007 wurde das metabolische Syndrom in seiner Bedeutung als Risikofaktor dem Diabetes mellitus gleichgesetzt. Bei der Behandlung von Patienten mit einer Hypertonie Grad 2 und 3, einem hohen kardiovaskulären Risiko und niedrigem Zielblutdruck sollte bereits zu Beginn der Behandlung eine “Kombinationstherapie” erwogen werden. In der Differentialtherapie besteht für ACE‐Hemmer und Angiotensinrezeptor‐Antagonisten eine neue Indikation in der Prävention des Vorhofflimmerns und des Diabetes mellitus Typ‐2.

Während α‐Blocker bereits ihre Position als Antihypertensiva der ersten Wahl verloren haben, wird gegenwärtig auch die Bedeutung der β‐Blocker in der initialen Therapie der primären Hypertonie kritisch diskutiert. Dies ist vor allem auf die schlechten Ergebnisse bei der Schlaganfallsprävention zurückzuführen. Darüber hinaus erhöhen β‐Blocker und Thiazide das Diabetesrisiko. Insbesondere Thiazide scheinen über eine therapieassoziierte Hypokaliämie die Insulinsekretion negativ zu beeinflussen. Der klinische Stellenwert von Askiren, einem neuen oral verfügbaren Renin‐Antagonisten, muss erst im Rahmen klinischer Studien genauer definiert werden.
Using video analysis to illuminate professional–patient interaction of clinical interventions
Authors: Virta Lena , Eriksson Rikard
Published: June 2008

Evidence‐based practice in physiotherapy should include reasoning as well as definition of practice knowledge and manual skills. The aim of this study was to explore how patients and physiotherapist interact in a situation of motor learning. Six patients with the diagnosis of subacromial impingement were video‐filmed during 11 treatment sessions with the same physiotherapist. The aim of the treatment was to improve their initial pattern of movement in arm elevation. The films were analysed with content analysis and the results are presented in three content areas: the context, interaction and professional skills. Further development of methodology, including computer aids for transcriptions, will make digital video analysis an interesting research method for physiotherapists. Copyright © 2008 John Wiley & Sons, Ltd.
Interconnection of the parameters obtained from the dielectric spectrum of CaF2 doped with ErF3 and YbF3
Authors: Vassilikou‐Dova Aglaia , Katsika‐Tsigourakou Vassiliki
Published: June 2008

A model has been suggested long ago that interconnects point defect parameters with bulk properties. On this basis, the ra‐tio of the migration entropy sm and the migration enthalpy hm should be equal to a bulk quantity. The validity of this prediction is studied here for the migration sm deduced from the pre‐exponential factor τ0 over the activation energy E involved in the Arrhenius relation τ = τ0 exp (E /kT) for the relaxation time τ. The study is focused on the so called RI‐relaxation in CaF2 doped with ErF3 and YbF3. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of static and dynamic properties of orthorhombic multiferroic substances
Authors: Wesselinowa J. M. , Georgiev I.
Published: June 2008

The influence of the magnetoelectric coupling and the exchange interaction constants on different magnetic and dielectric properties of orthorhombic RMn2O5 multiferroic materials is studied based on the transverse Ising and Heisenberg models using a Green's function technique. In the vicinity of the phase transition temperature TC we obtain an anomaly, a kink in the temperature dependence of the magnetic properties. This is due to the coexistence of ferroelectricity and magnetism which leads to interplay between the electric and magnetic properties. The spin excitations show a novel softening around TC due to the magnetoelectric coupling. The effect of external electric and magnetic fields is also calculated. We obtain the magnetic‐field‐induced polarization and the electric‐field‐induced magnetization. The obtained results are in qualitative agreement with the experimental data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of magnetization processes using higher harmonic ac‐susceptibility
Authors: Prüfer S. , Ziese M.
Published: June 2008

The ac‐susceptibility of a La0.7Sr0.3MnO3 epitaxial film was measured up to the 11th harmonic as a function of ac‐field amplitude, superimposed dc‐field and temperature. The experimental data reflect the magnetization hysteresis‐loop shape in a very precise and detailed way. This is further elucidated by numerical simulations of the ac‐susceptibility within a Preisach model with Gaussian distribution function. Using parameters from magnetization measurements the simulated ac‐susceptibility curves were found to be in good agreement with the experimental results. This shows that measurements of higher harmonic susceptibilities are a powerful tool for the precise study of magnetization processes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)