bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser desorption/ionization techniques in the characterization of high molecular weight oil fractions. Part 1: asphaltenes
Authors: Rizzi Andrea , Cosmina Paola , Flego Cristina , Montanari Luciano , Seraglia Roberta , Traldi Pietro 
Published: August 2006

AbstractThe molecular weight distribution of the asphaltene fractions of two types of crude oils from two different Italian fields (samples 1 and 2) was investigated. The analytical tools used to perform these analyses were matrix assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) mass spectrometry. After observing that the use of the matrix (as well as the addition of Ag+) did not improve the quality of the data compared to that obtained in LDI conditions, all further measurements were performed with the latter technique. Operating under usual conditions of laser power and delay time, a very low resolution was observed, showing only macroscopic differences between the two samples in the molecular weight distribution of the different components. An accurate study on the possible reasons of this undesirable behavior indicates that it can originate from space charge phenomena occurring either in the ion source region or during the flight. A valid parameterization of the delay time and the laser power allowed higher quality spectra to be obtained. Surface‐enhanced laser desorption ionization (SELDI) measurements were also performed using normal phase (silica) as the sample holder surface. Under these conditions, better results are obtained, proving that the sample–surface interaction is important to achieve, by means of laser irradiation, a homogeneous set of product ions. Both asphaltene samples were fractionated in five subfractions by gel‐permeation chromatography (GPC) to obtain a better separation of the molecular weight distributions; the related spectra confirmed these findings. By using different approaches, relevant and reproducible differences between the asphaltene fractions of the two oil samples were observed. Copyright © 2006 John Wiley & Sons, Ltd.
Lactacystin decreases amyloid‐β peptide production by inhibiting β‐secretase activity
Authors: Kienlen‐Campard Pascal , Feyt Christine , Huysseune Sandra , de Diesbach Philippe , N'Kuli Francisca , Courtoy Pierre J. , Octave Jean‐Noël 
Published: August 2006

AbstractThe human amyloid precursor protein (APP) is processed by the nonamyloidogenic and the amyloidogenic catabolic pathways. The sequential cleavage of APP by the β‐ and γ‐secretase activities, known as the amyloidogenic processing of APP, leads to the formation of the amyloid‐β peptide (Aβ). Aβ is the main constituent of the amyloid core of senile plaques, a typical hallmark of Alzheimer's disease. In addition to secretases, other cellular proteolytic activities, like the proteasome, might participate in the metabolism of APP. We investigated the consequence of proteasome inhibition on the amyloidogenic processing of human APP. CHO cells and primary cultures of rat cortical neurons expressing human APP or a protein corresponding to its β‐cleaved C‐terminal fragment (C99) were treated with lactacystin, an irreversible inhibitor of the chymotrypsin‐like activity of the proteasome. Lactacystin significantly decreased the level of Aβ produced from APP in both cellular models, whereas the production of Aβ from C99 was not affected. Lactacystin did not inhibit γ‐secretase activity but was found to inhibit the β‐cleavage of APP, leading to a proportional decrease in Aβ production. Although lactacystin did not inhibit the catalytic activity of recombinant BACE1, a decrease in neuronal β‐secretase activity was measured after treatment with lactacystin. © 2006 Wiley‐Liss, Inc.
Unaltered neuropeptide Y (NPY)‐stimulated [35S]GTPγS binding suggests a net increase in NPY signalling after repeated electroconvulsive seizures in mice
Authors: Christensen D.Z. , Olesen M.V. , Kristiansen H. , Mikkelsen J.D. , Woldbye D.P.D. 
Published: August 2006

AbstractAlthough electroconvulsive seizures (ECS) are widely used as a treatment for severe depression, the working mechanism of ECS remains unclear. Repeated ECS causes anticonvulsant effects that have been proposed to underlie the therapeutic effect of ECS, and neuropeptide Y (NPY) is a potential candidate for mediating this anticonvulsant effect. Repeated ECS results in prominent increases in NPY synthesis. In contrast, NPY‐sensitive receptor binding is decreased, so it is unclear whether ECS causes a net increase in NPY signalling. Agonist‐stimulated [35S]GTPγS binding is a method for detecting functional activation of G‐protein‐coupled receptors. The present study in mice examined the effects of daily ECS for 14 days on NPY‐stimulated [35S]GTPγS functional binding and compared this with gene expression of NPY and NPY receptors as well as [125I]peptide YY (PYY) binding in hippocampus of the same animals. Significant increases in NPY mRNA and concomitant reductions in NPY‐sensitive binding were found in the dentate gyrus, hippocampal CA1, and neocortex of ECS treated mice, which is consistent with previous rat data. These changes remained significant 1 week after repeated ECS. Significant increases in NPY Y1, Y2, and Y5 mRNA were found in the dentate gyrus after ECS. Surprisingly, unaltered levels of functional NPY receptor binding accompanied the decreased NPY‐sensitive binding. This suggests that mechanisms coupling NPY receptor stimulation to G‐protein activation could be augmented after repeated ECS. Thus increased synthesis of NPY after repeated ECS should result in a net increase in NPY signalling in spite of reduced levels of NPY‐sensitive binding. © 2006 Wiley‐Liss, Inc.
Phagocytosis of apoptotic inflammatory cells downregulates microglial chemoattractive function and migration of encephalitogenic T cells
Authors: Chan Andrew , Hummel Vera , Weilbach Franz X. , Kieseier Bernd C. , Gold Ralf 
Published: August 2006

AbstractApoptosis of autoaggressive T cells in the central nervous system (CNS) and subsequent phagocytosis by microglia is probably crucial in the rapid resolution of the inflammatory infiltrate in T cell mediated neuroinflammatory diseases. In addition to mere clearance, phagocytosis of apoptotic leukocytes results in the downregulation of different microglial immune functions. Chemoattractive functions of Lewis rat microglia and secretion of chemokines and matrix‐metalloproteinases (MMPs) were investigated after phagocytosis of apoptotic T cells in vitro. In a modified Boyden chamber assay migration of encephalitogenic T cells toward LPS‐stimulated microglial supernatants after phagocytosis of apoptotic thymocytes was reduced by 24.9% in comparison to interaction with viable target cells (P < 0.001). Phagocytosis of apoptotic cells downregulated CC‐chemokine ligand (CCL)‐5‐secretion by LPS‐stimulated microglia by 66.2% (P < 0.001), whereas there was only a trend toward decreased CCL2‐secretion. As determined by gelatinase‐zymography, secretion of MMP‐9 by microglia was decreased after phagocytosis of apoptotic cells, whereas MMP‐2 secretion was not altered. These mechanisms may reduce further recruitment of pathogenic inflammatory cells into the CNS‐lesion and thus contribute to the active resolution of the inflammatory infiltrate and termination of the autoimmune attack. © 2006 Wiley‐Liss, Inc.
Knockdown of uncoupling protein‐5 in neuronal SH‐SY5Y cells: Effects on MPP+‐induced mitochondrial membrane depolarization, ATP deficiency, and oxidative cytotoxicity
Authors: Ho Philip Wing‐Lok , Chu Andrew Chi‐Yuen , Kwok Ken Hon‐Hung , Kung Michelle Hiu‐Wai , Ramsden David Boyer , Ho Shu‐Leong 
Published: August 2006

AbstractUncoupling proteins (UCPs) uncouple oxidative phosphorylation from ATP synthesis by dissipating proton gradient across mitochondrial inner membrane. The physiological role of neuronal specific UCP5 is unknown. We explored the effects of reduced UCP5 expression on mitochondrial membrane potential (MMP), oxidative stress, ATP levels, and cell viability, under normal and MPP+‐induced cytotoxic conditions, in human catecholaminergic SH‐SY5Y cells. UCP5 expression was reduced by 56% by siRNA, compared to scrambled‐siRNA controls. UCP5 knockdown induced apoptosis but did not affect basal levels of ATP, oxidative stress and MMP in the cells under normal conditions. However, UCP5 knockdown increased MPP+‐induced cytotoxicity by 15% and oxidative stress levels by 40%, and partially restored MPP+‐induced mitochondrial depolarization by 57%. UCP2 and UCP4 expression were unaffected by UCP5 knockdown. Exacerbation of cytotoxicity, oxidative stress and modification of MMP with reduced UCP5 expression in the face of MPP+ toxicity suggest that UCP5 might be physiologically important in the pathology of oxidative stress‐induced neurodegeneration. © 2006 Wiley‐Liss, Inc.
Raman scattering investigations of the low‐temperature phase transition of NaNbO3
Authors: Lin S. J. , Chiang D. P. , Chen Y. F. , Peng C. H. , Liu H. T. , Mei J. K. , Tse W. S. , Tsai T.‐R. , Chiang H.‐P. 
Published: August 2006

AbstractIn this work, we report the low‐temperature phase transition of sodium niobate (NaNbO3) ceramics at the antiferroelectric–ferroelectric phase studied by the Raman scattering technique over the temperature range 10–300 K. The spectral shape indicates that the phase transition occurs at 160 K on the cooling cycle and at 260 K on heating. The recorded spectra are discussed following the separation of modes into the internal stretching modes of the NbO6 octahedron and Na+ cation translational modes. The 62 and 75 cm−1 peaks are proposed as the translational modes of Na+ cation against the NbO6 octahedron. Copyright © 2006 John Wiley & Sons, Ltd.
The effect of applied tensile stress on the exfoliation corrosion of 7075‐T6 alloy
Authors: Su J. , Zhang Z. , Shi Y. , Yang Z. , Zhang J. , Cao C. 
Published: August 2006

AbstractThe effect of the applied tensile stress on the exfoliation corrosion of 7075‐T6 alloy in EXCO solution has been studied. Electrochemistry Impedance Spectroscopy (EIS), Scanning Electron Microscope (SEM) and optical microscope techniques were used to characterize the initiation and propagation of the exfoliation corrosion (EC) under different applied tensile stress levels. Two equivalent circuit models were developed to fit the EIS data of the initiation and propagation stages of EC according to their corresponding physicochemical properties respectively. The correlation between the characteristics of EIS evolution and the localized corrosion types was established, and a new criteria for detecting the initiation of EC of aluminum alloys was brought forward. The results also showed that the tensile stress accelerates EC by increasing the number of the active sites during its initiation stage.
The cavitation erosion and erosion‐corrosion behavior of carbon steel in simulating solutions of three rivers of China
Authors: Yu H. , Zheng Y. G. , Yao Z. M. 
Published: August 2006

AbstractThe corrosion behaviour of the Q235 carbon steel in simulation solution of Yangtze, Yellow and Talimu river of China was investigated by mass loss, electrochemical measurements (polarization curves, linear polarization resistance and electrochemical impedance spectroscopy) and the damaged surfaces were observed by a scanning electron microscope (SEM) under static, cavitation erosion and erosion‐corrosion conditions. It was shown that under static condition, the Ecorr was almost the same in the three solutions but the anodic current density in Talimu river was about one order of magnitude larger than that in Yangtze and Yellow river. Under dynamic conditions including cavitation erosion and erosion‐corrosion, the Ecorr in the three solutions all shifted in positive direction from that under static condition, but the extent of ΔEcorr increased in the order of Yangtze, Yellow and Talimu river. The corrosion rate under dynamic conditions greatly enhanced, especially in Talimu river. It was confirmed that the corrosion played an important role in the synergistic effect under cavitation erosion and erosion‐corrosion conditions. The test results suggested that when the structure materials used in the different rivers were chosen, the difference of corrosiveness of the rivers must be taken into account, especially under dynamic conditions. The materials used in the aggressive rivers such as Talimu river under dynamic conditions must resist the synergistic effects between erosion and corrosion.
Evolution of a Metallocenic sPP with Time: Changes in Crystalline Content and Enthalpic Relaxation
Authors: Arranz‐Andrés Javier , Benavente Rosario , Ribeiro M. Rosário , Pérez Ernesto , Cerrada Maria L. 
Published: August 2006

AbstractSummary: The structural evolution of a metallocenic syndiotactic poly(propylene), sPP, with time has been studied. Due to the low syndiotactic content, the analyzed sPP sample can be easily quenched to a completely amorphous state. This amorphous sample, when left at room temperature is able to crystallize at relatively long times. The degree of crystallinity, as a function of time, has been analyzed by X‐ray diffraction and DSC. The DSC melting curves show the presence of a very important low‐temperature endotherm, besides the main melting peak. Real‐time variable–temperature synchrotron experiments have been performed in order to analyze the origin of the two melting peaks. They seem to arise from the melting of two populations of sPP crystals with different size and/or perfection, rather than from the melting of different polymorphs. The changes in the crystalline regions are accompanied by important variations in the mechanical behavior, as revealed by DMTA and microhardness (MH) measurements. In addition, the sPP crystallization has been analyzed by MH measurements, showing the importance that a relative low crystallinity has on the stiffness of a polymeric material at temperatures above Tg. On the other hand, the kinetics of the enthalpic recovery of quenched amorphous sPP specimens has been analyzed by DSC with temperature modulation. It was found that this enthalpic relaxation can be described by the KWW model, and the relaxation times and shape parameters at three different aging temperatures have been determined, with the corresponding apparent activation energy of this process.Variation with temperature of the most probable long spacing of sPP.imageVariation with temperature of the most probable long spacing of sPP.
New Siloxane‐Organic Polyesters with Azobenzene Side Chains. Synthesis, Thermotropic Behavior and Surface Properties
Authors: Racles Carmen , Filip Daniela , Cazacu Maria , Cozan Vasile , Tóth András , Ioanid Ghiocel 
Published: August 2006

AbstractSummary: New siloxane‐organic polyesters, bearing azo‐type units in the side chain, were synthesized by direct solution polycondensation at room temperature, starting from 2,2′‐[4‐[(4‐nitrophenyl)azo]phenyl]iminobisethanol (Disperse Red 19) and different siloxane diacids, using dicyclohexylcarbodiimide as an activator and 4‐(N,N‐dimethylamino)pyridinium‐p‐toluenesulfonate as the catalyst. The structure of the obtained polyesters was confirmed by 1H and 13C NMR as well as IR spectroscopy. The molecular weight and polydispersity were estimated by GPC. The thermotropic behavior was investigated by POM, DSC and TOA. The surface composition was determined by ESCA (XPS) analysis and proved enrichment in silicon for all samples. All compounds show good solubility in common organic solvents.An example of a nitroazobenzene‐containing side‐chain polyester with various siloxane‐organic backbones.imageAn example of a nitroazobenzene‐containing side‐chain polyester with various siloxane‐organic backbones.
NMR Microscopy: A Tool for Measuring Monomer Diffusion in Supercritical CO2
Authors: Thurecht Kristofer J. , Hill David J. T. , Whittaker Andrew K. 
Published: August 2006

AbstractSummary: The diffusion of styrene into linear low density polyethylene in a solution of supercritical CO2 was investigated using NMR microimaging. For both pure styrene and styrene dissolved in supercritical CO2, the diffusion was found to follow Fickian kinetics. Supercritical CO2 was found to enhance the rate and extent of diffusion of styrene into the substrate by up to three times under the conditions of this investigation, compared to pure styrene. NMR imaging was used to measure the concentration profiles of the styrene penetrants in real time, and the results were fitted to a Fickian model for diffusion. At a CO2 pressure of 150 bar and temperature of 40 °C, the diffusion coefficient of a 30 wt‐% solution of styrene into LLDPE was calculated to be 1 × 10−11 m2 · s−1. This is significantly faster than the diffusion coefficient measured for pure styrene diffusion at 40 °C (3 × 10−12 m2 · s−1). The diffusion coefficients determined by gravimetric analysis were slightly higher than those determined by the imaging method. This was probably due to residual styrene and/or polystyrene adhering to the surface of the films in the gravimetric technique.NMR image of styrene in linear low density polyethylene following supercritical fluid enhanced impregnation.imageNMR image of styrene in linear low density polyethylene following supercritical fluid enhanced impregnation.
New electronic scanning traveling‐wave antenna array
Authors: Alaeddine A. , Rammal M. , Bazzi O. , Mohanna Y. , Reineix A. 
Published: August 2006

AbstractA plan traveling‐wave array to realize an electronic scanning antenna is described. A theoretical analysis of the microstrip antenna and experimental results of the series‐fed element array are presented. An efficient synthesis method is used to produce the desired radiated patterns like side lobes and high gain. Eight elements of the linear traveling‐wave series‐fed array were used and tested. High performance and good gain have been observed over a relatively large band. For a frequency shift of 100 GHz, the lobe scanned 2°. This array promises to be a candidate in an electronic scanning antenna. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2186–2189, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21882
Double‐ridged horn antenna for millimeter‐wave applications
Authors: Moon Jung‐Ick , Yun Jae‐Hoon 
Published: August 2006

AbstractThis study presents a broadband double‐ridged horn antenna for millimeter‐wave applications. The proposed broadband antenna has a bandwidth of 12.1–63.2 GHz and peak radiation gain of 12.1–19.8 dBi. The performance of this antenna is verified by the measured results and is in good agreement with the simulated results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2165–2167, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21884
A novel bandpass filter using a dual‐mode square patch resonator with combined CPW and microstrip input/output
Authors: Bo Y. M. , Huang X. D. , Cheng C. H. 
Published: August 2006

AbstractA novel bandpass filter using a dual‐mode square‐patch resonator is proposed in this article. The input and the output of the filter are constructed on a coplanar‐waveguide (CPW) and a microstrip line, respectively. Therefore, a transition of CPW/microstrip may be simultaneously realized by using the filter. The filter has been investigated numerically and experimentally. Results show that the minimum insertion loss in the passband of the filter is about 2.1 dB and its out‐of‐band rejection level is below −23 dB. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2184–2186, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21885
Multiple‐grating microwave volume holograms based on printed artificial dielectrics: Analysis and measurement
Authors: Zhu Wenhao , McNamara Derek A. , Shaker Jafar 
Published: August 2006

AbstractA multiple‐grating artificial microwave volume hologram (AMVH) is presented, which is designed based on the idea of multiply‐exposed optical holograms and is realized using printed artificial dielectric technique. It consists of a 3D conducting disk array formed by cascading a finite number of planar disk lattices and has its disk size varying in both the transverse (x) and normal (z) directions to simulate an effective 2‐D holographic grating. The reconstructed beams from such a multiplex AMVH are analyzed and a low cross‐talk between gratings is obtained. Comparison with the measured results on the fabricated multiplex AMVH prototype has confirmed the design and simulation. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2179–2184, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21886
A subharmonically injected phase‐locked loop for 5‐GHz applications
Authors: Plessas Fotis , Kalivas Grigorios 
Published: August 2006

AbstractThis work introduces a modified subharmonic injection‐locked phase‐locked loop (S‐ILPLL) that feeds the phase comparator with half the frequency of the voltage‐controlled oscillator by employing a divider in the loop feedback path. The main objective is to address the phase noise improvement of subharmonic ILPLLs, especially for the 5‐GHz band. Theoretical analysis and computer calculations demonstrate an improved performance for phase noise and power consumption. An experimental prototype was implemented to verify the validity of the proposed approach. Measurement results are in good agreement with computer calculations, thus the proposed S‐ILPLL can constitute an attractive design approach for 5‐GHz WLAN synthesizers. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2158–2162, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21888
FHSS optical wireless transceiver for short range low‐speed indoor sensor interconnection
Authors: Delgado F. , Jiménez R. Pérez , Pérez S. , González O. 
Published: August 2006

AbstractExperimental and simulation results from the operation of a prototype of wireless indoor optical transceiver based on frequency hopping techniques are presented. We choose spread spectrum techniques, as it allows multiple simultaneous accesses and also increases the robustness of the system against multipath‐induced distortion. It also reduces the effect of narrowband interference, as could be low‐frequency optical noise from fluorescence or incandescence lamps. FHSS techniques also allow coexistence with IrDA or remote control emitting devices without causing of suffering interferences. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2193–2197, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21889
Investigation on probe‐fed open‐ring microstrip antenna for miniaturization
Authors: Latif Saeed I. , Shafai Lotfollah 
Published: August 2006

AbstractGap‐loaded microstrip square‐ring antennas are investigated in this study. Because of the gap loading, the square‐ring antenna resonates at much lower frequency than that in the unloaded case, which gives a miniaturized narrowband antenna. A detail parametric study is carried out to understand its properties. An experimental prototype is fabricated and its performance is compared with simulations, confirming the computed results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2175–2179, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21890
TLM modelling of microwave applicator with an excitation through the waveguide
Authors: Joković Jugoslav , Milovanović Bratislav , Ranđelović Tijana 
Published: August 2006

AbstractA microwave applicator with a waveguide used to launch the energy from the source into the metallic cavity is modelled using 3D‐TLM method. An influence of waveguide position to the resonant modes distribution inside both empty and loaded cavities is analyzed, comparing numerical results with analytical and experimental ones. © Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2320–2326, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21895