bluuebunny/crossref_metadata_2025_split huggingface dataset:
Holocene vegetation and land‐use changes in response to climatic changes in the forelands of the southwestern Alps, Italy
Authors: Finsinger Walter , Tinner Willy 
Published: February 2006

AbstractThe Holocene sediment of Lago Piccolo di Avigliana (Piedmont, Italy, 356 m a.s.l.) was dated by 14C and analysed for pollen to reconstruct the vegetation history of the area. The early‐ and mid‐Holocene pollen record shows environmental responses to centennial‐scale climatic changes as evidenced by independent palaeoclimatic proxies. When human impact was low or negligible, continental mixed‐oak forests decreased at ca. 9300 BC in response to the early‐Holocene Preboreal climatic oscillation. Abies alba expanded in two phases, probably in response to higher moisture availability at ca. 6000 and ca. 4000 BC, while Fagus expanded later, possibly in response to a climatic change at 3300 BC.During and after the Bronze Age five distinct phases of intensified land use were detected. The near synchroneity with the land‐use phases detected in wetter regions in northern and southern Switzerland points to a common forcing factor in spite of cultural differences. Increasing minerogenic input to the lake since 1000 BC coincided with Late Bronze—Iron Age technical innovations and probably indicate soil erosion as a consequence of deforestation in the lake catchment. The highest values for cultural indicators occurred at 700–450 and at 300–50 BC, coinciding with periods of high solar activity (inferred from Δ14C). This suggests that Iron Age land use was enhanced by high solar activity, while re‐occupation of partly abandoned areas after crises in earlier periods match better with the GRIP stable isotope record. On the basis of our data and comparison with independent palaeoclimatic proxies we suggest that precipitation variation was much more important than temperature oscillations in driving vegetation and societal changes throughout the Holocene. Copyright © 2006 John Wiley & Sons, Ltd.
Late Quaternary glacial and deglacial history of eastern Vestfirdir, Iceland using cosmogenic isotope (36Cl) exposure ages and marine cores
Authors: Principato Sarah M. , Geirsdóttir Áslaug , Jóhannsdóttir Gudrún Eva , Andrews John T. 
Published: February 2006

AbstractThe late glacial and deglacial history of Vestfirdir, NW Iceland is interpreted from terrestrial field‐based evidence and compared with marine cores and seismic studies. Understanding the timing of deglaciation is complicated by a lack of dateable organic material on land, uncertainties associated with interpretation of diamictons, and ambiguities in radiocarbon dating. New36Cl exposure ages of boulders and bedrock surfaces suggest that at least part of the coastal uplands were ice‐free by approximately 20 ka. Deglaciation of the valleys followed. Boulders from the crest of an end‐moraine in the Selá river valley have a mean36Cl age of 14.6 ka ± 0.8 ka (n = 4), and the outermost moraine in the valley adjacent to Kaldalónjökull has a mean36Cl age of 11.7 ka ± 0.9 ka (n = 2). Tephrochronology provides a link between the terrestrial and marine sequences around Vestfirdir. The Vedde Ash (ca. 12 k cal. yr BP) is present in some offshore cores, but it is absent from terrestrial sites, suggesting that its distribution provides a constraint on ice extent during the Younger Dryas. The Saksunarvatn Ash (10.2 ± 0.6 k cal. yr BP), confirmed by geochemical analyses and radiocarbon dating, is present in at least three terrestrial locations on eastern Vestfirdir and in many cores from the fjords and shelf, which constrains early Holocene ice extent. Copyright © 2006 John Wiley & Sons, Ltd.
Hybrid Hydrogels Self‐Assembled from HPMA Copolymers Containing Peptide Grafts
Authors: Yang Jiyuan , Xu Chunyu , Kopečková Pavla , Kopeček Jindřich 
Published: March 2006

AbstractSummary: Graft copolymers were designed that self‐assemble into hydrogels mediated by the interaction of coiled‐coil peptide domains. A linear hydrophilic polymer of HPMA was chosen as the backbone, and coiled‐coil forming peptides, covalently attached to the backbone, formed the grafts. Microrheology was used to evaluate the self‐assembly of graft copolymers into hydrogels. The results revealed that the length and the number of coiled‐coil grafts per chain had a significant influence on the gelation process. At least 4 heptads were needed to achieve the association of graft copolymers into hydrogels. CD spectra of the copolymer containing 5 heptad grafts further suggested that coiled‐coil formation may contribute to the self‐assembly. Gelation of graft copolymers containing CC4 peptides indicated that a threshold amount of grafts per macromolecule is needed to form a three‐dimensional structure. These studies demonstrated a potential of the graft copolymers to create self‐assembling hydrogels with desirable and controllable structures.
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A Reversible and Highly Selective Fluorescent Sensor for Mercury(II) Using Poly(thiophene)s that Contain Thymine Moieties
Authors: Tang Yanli , He Fang , Yu Minghui , Feng Fude , An Lingling , Sun Huan , Wang Shu , Li Yuliang , Zhu Daoben 
Published: March 2006

AbstractSummary: A reversible and highly selective assay method has been developed to detect mercury(II) (Hg2+) ions using a conjugated polymer (CP). The transduction mechanism is based on Hg2+‐mediated interpolymer π‐stacking aggregation, which results in the fluorescence self‐quenching of the CP. CPs that contain thymine moieties, poly[3‐(N‐thymin‐1‐ylacetyl)ethylamine‐thiophene] (PTT), have been synthesized and characterized. In the absence of Hg2+ ions, the PTT chains remain separated from each other and the CP exhibits strong fluorescence emission. Upon adding Hg2+ ions, the formation of interpolymer π‐stacking aggregation induced by specific thymine–Hg–thymine interactions results in the fluorescence quenching of PTT. Distinguishing aspects of this assay include the signal amplification of CPs and the specific binding of Hg2+ ions to thymine‐thymine (T–T) base pairs.The binding of Hg2+ ions causes the separate conducting polymer chains to aggregate with subsequent fluorescence self‐quenching.magnified imageThe binding of Hg2+ ions causes the separate conducting polymer chains to aggregate with subsequent fluorescence self‐quenching.
Hydrophilicity Impact upon Physical Properties of the Environmentally Friendly Poly(3‐hydroxybutyrate) Blends: Modification Via Blending
Authors: Iordanskii Alexey L. , Ol'khov Anatoliy A. , Pankova Yulia N. , Bonartsev Anton P. , Bonartseva Garina A. , Popov Vladimir O. 
Published: March 2006

AbstractWe have integrated scientific research of polymer blends on the base of poly‐3‐hydroxybutyrate (PHB and its copolymers) with bench testing in blend preparation by both solvent casting and melt extrusion. As a second component, we have used traditional synthetic macromolecules with various hydrophilicity degree and hence with different morphologies and physical behavior. Besides, variation of polymer hydrophilicity permits to control both the service characteristic and the rate of (bio)degradation operating in the presence of water. Therefore, a substantial part of our work is devoted to water transport in the parent PHB and its blends. Combining the morphology knowledge (SEM, WAXS, FTIR tecynique), transport characteristics (permeability cells and McBain spring microbalance), and mechanical testing, we propose that blending of the parent biodegradable polymer with synthetic macromolecules is a perspective tool to design novel materials with improved characteristics. Both the water transport coefficients and the mechanical characteristics are essentially sensitive to structure and morphology of the blends. Hydrophilicity variation in the order LDPE < SPEU < PVA at blending with PHB shows that the morphology transformation in immicsible or partly miscible blends shifted along the PHB concentration scale as LDPE (at ∼16 wt% PHB) < PVA (∼30 wt% PHB) < SPEU (∼50 wt% PHB) Our instrumental monitoring the structural hierarchy of parent polymers and their blends as well as , simultaneously, the study of transport processes, their modeling, and computer simulating open up the way to understanding the precepts of polymer operation in corrosive and bioactive media.
Thermo‐mechanical Properties of In‐situ Silica Filled Silicone Resins
Authors: Chevalier Pierre , Ou Duan‐Li , Lee Yeong , Robson Steven , Dupont Anne 
Published: March 2006

AbstractSilicone resins were investigated as a replacement of silica filled organic polymers for microelectronic packaging. Self‐curable silicone resins containing up to 40 mol% of in‐situ generated silica‐like species were prepared by a novel process involving controlled hydrolysis‐condensation of SiH moieties without gelation. These in‐situ Q filled resins are stable and easy to process compared to post‐filled organic polymers. The thermo‐mechanical properties upon self‐addition and condensation cure of the in‐situ filled silicone resins are superior to conventional addition and condensation cured silicone resins and are in the range of organic polymers with the added advantage of high thermal and moisture resistance critical in microelectronic. Storage modulus and plateau modulus as high as 3.5 GPa with a very low fall in modulus below 5% were demonstrated. Coefficients of thermal expansion were as low as 55 to 65 ppm/K in the application temperature up to 170 °C.
Polypropylene/Nylon‐66/Carbon Black Blends Processed at Temperatures Just Below the Nylon Melting: Anisotropy in Structure and Properties
Authors: Zoldan Janet , Siegmann Arnon , Narkis Moshe 
Published: March 2006

AbstractIn‐situ fibrillation of nylon (Ny) is obtained by compounding and processing its binary blends with polypropylene (PP) and ternary carbon black (CB) containing blends just below the melting temperature (Tm) of the dispersed, Ny phase, yet, above that of the PP. At such low temperatures the Ny behaves as an elastic solid deforming under the elongational flow of the molten PP matrix. Without the mediation of PP, Ny could not be processed or compounded at such low temperatures. This structured anisotropy in both binary and ternary blends resulted in anisotropy in the electrical and dielectric properties of the blends. Moreover, the dynamic electrical behavior was used as a powerful tool to study the CB dispersion mode in the polymer blends.
Development of PVC/Silica Hybrids Using PVC Plastisols
Authors: Gilbert Marianne , Haghighat Siavash , Chua Soo Keow , Ng Soo Yeng 
Published: March 2006

AbstractA novel method for producing a plasticised PVC with increased porosity has been developed, by the use of an organic‐inorganic hybrid. Silica was produced in situ from tetraethoxysilane via a hydrolytic sol‐gel processing route. Tetrahydrofuran was used as co‐solvent, and γ‐glycidyloxypropyl‐trimethoxysilane as coupling agent. The films produced were transparent, with moderate mechanical properties. A film containing 20% silica showed a 45% increase in water vapour permeability.
High Barrier Polyamide/Polyolefin/Organoclay Nanocomposites
Authors: Brulé Benoît , Flat Jean‐Jacques 
Published: March 2006

AbstractNew composites coupling the alloy and nanocomposite technologies have been successfully produced with regular co rotating twin screw extruder. These new composites, Polyamide(PA6)/Polyolefin(PO)/compatibilizer/nanoclay, have been blown to end up with monolayer films. The thermo mechanical performances of these new composites do not reveal any improvement at high temperature resulting from the presence of nanoclays, as required by emergent needs in automotive field. More interesting are the high barrier properties obtained with these new composites. For specific permeating species, the association of alloy and nanocomposite technologies lead to new materials with superior barrier performances comparing to the materials making up the alloys. Physical explanation of such behavior is detailled in this paper.
Nanostructured Composites with Layered Morphology: Structure and Properties
Authors: Adhikari Rameshwar , Henning Sven , Michler Goerg H. 
Published: March 2006

AbstractUsing different microscopic techniques, we investigate the morphology and the micro‐deformation processes in two entirely different classes of polymer based composites: natural biocomposites and synthetic polymer composites. The emphasis has been put on the comparison of the micromechanical properties of those composite materials. In the natural layered composites exemplified by human cortical bone, analogous to the synthetic glassy polymers, craze‐like deformation zones were formed. A strong dependence of deformation mechanisms (such as transition from formation of single crazes to multiple crazing behaviour) on the layer dimension was observed in the layered composites made up of different amorphous polymers.
Mechanical Properties and Hysteresis Behaviour of Multigraft Copolymers
Authors: Staudinger U. , Weidisch R. , Zhu Y. , Gido S. P. , Uhrig D. , Mays J. W. , Iatrou H. , Hadjichristidis N. 
Published: March 2006

AbstractPS‐PI multigraft copolymers with tri‐ tetra‐ and hexafunctional polystyrene branch points have been studied to investigate the influence of molecular architecture on morphological and tensile properties and to find novel material concepts. It was found that the morphological behaviour of these grafted copolymers can be predicted using theoretical approaches. The number of branch points, however, greatly influences the long‐range order of microphase separation. Additionally, two new parameters for adjusting mechanical properties of multigraft copolymers are found in our investigations: 1) functionality of the graft copolymer: tri‐, tetra‐ or hexafunctional and 2) number of branch points per molecule. Tetrafunctional multigraft copolymers show surprising high strain at break values up to 1550 %. With increasing number of branch points strain at break and tensile strength increase, where a linear dependence of mechanical properties on the number of branch points is obvious. Excellent elasticity of tetra and hexafunctional multigraft copolymers at high deformation was proved in hysteresis experiments.
The Effect of the Compatibilization Route of PA/PO Blends on the Physico‐chemical Phenomena Developing Along a Twin‐screw Extruder
Authors: Vera Machado Ana , Yquel Virginie , Covas José Antonio , Flat Jean‐Jacques , Ghamri Nessim , Wollny Andreas 
Published: March 2006

AbstractThe effect of the compatibilization method (ex‐situ, in‐situ, cross linking) on the chemical conversion, morphological and rheological evolution of polyamide/polyolefin blends along a twin screw extruder is investigated. For this purpose, samples were quickly collected from the extruder at specific barrel locations, quenched and subsequently characterized off‐line. While significant changes occur very quickly in the melting zone for the ex‐situ and in‐situ routes, changes of the cross linking system could be detected along all the extruder. Correlations between chemical conversion, particle size and linear viscoelastic response could be established.
Conducting Elastomer Blends Based on Nitrile Rubber and Pani.DBSA
Authors: Soares Bluma G. , Amorim Gabriel S. , Oliveira Marcia G. , Pereira da Silva J.E. 
Published: March 2006

AbstractElectrically conductive elastomer blends based on polyaniline‐dodecylbenzene sulfonic acid (Pani.DBSA) and nitrile rubber (NBR) were prepared by polymerization of aniline in the presence of NBR, using a direct, one‐step in situ emulsion polymerization method. At the same PAni content, the conductivity of the in situ emulsion‐polymerized blends is higher than that of blends produced by mechanical mixing of both components. In addition, a morphology with the presence of PAni in the form of microtubules was achieved by the in situ process. Stronger interaction between the components were also confirmed by Rheological processing analysis (RPA). The vulcanization process decreases the conductivity of the blends prepared by both methods. The in situ polymerized blends also display higher tensile strength and also higher crosslink density
A switchable triple‐wavelength erbium‐doped fiber laser with a linear laser cavity
Authors: Liu D. , Ngo N. Q. , Chan H. N. , Teu C. K. , Tjin S. C. 
Published: February 2006

AbstractA simple and switchable triple‐wavelength erbium‐doped fiber laser (EDFL) with a linear laser cavity is proposed and experimentally demonstrated. In the experiment, by changing the state of polarization (SOP) inside the laser cavity through a polarization controller (PC), stable single, dual, and triple wavelengths under room temperature were obtained. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 632–635, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21429
3D analysis of a quasi circular microstrip antenna by finite element method
Authors: Bourry M. , Drissi M. 
Published: February 2006

AbstractIn this work a complementary study of an elliptical antenna circularly polarized designed on a glass substrate is proposed using a 3D finite‐element method that takes into account the finite size of the substrate. This simulation type gave more reliable results in near‐ and far‐field analyses that were performed using a compact‐range measurement system. The parasitic effect of the feeding line is confirmed in simulations and in measurements. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 635–639, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21430
New design concept of dual‐mode bandpass filter by using nonorthogonal input and output ports for wireless application
Authors: Chen Han‐Jan , Huang Tsung‐Hui , Chen Lih‐Shan , Horng Jui‐Hong , Houng Mau‐Phou 
Published: February 2006

AbstractIn this paper, new design concept of nonorthogonal input and output (I/O) ports applied to optimize dual‐mode bandpass ring filter is proposed. Compared to conventional dual‐mode filters, the proposed filter with nonorthogonal I/O could not only support two degenerate modes operation, but also increase design flexibility. Moreover, the design of dual‐mode filters would not have an I/O geometry limitation, corresponding to high integration. Finally, a simple structure and high selectivity for the dual‐mode bandpass filters were obtained. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 639–641, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21431
Broadband coaxial antenna for WiMAX access‐point application
Authors: Wong Kin‐Lu , Wu Chih‐Hsien , Chang Fa‐Shian 
Published: February 2006

AbstractA broadband coaxial antenna mainly comprising an upper square cylindrical plate and a lower square cylindrical ground is presented. The antenna functions like a two‐wire dipole antenna, and furthermore provides a wide operating bandwidth of about 4 GHz (about 1.9 to 5.9 GHz in the study), making it very promising for application in Worldwide Interoperability for Microwave Access Forum (WiMAX) access points. The antenna has been successfully implemented, and experimental results are presented. The effects of the lower square cylindrical ground on the antenna performances are also analyzed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 641–644, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21432
Miniaturized low‐loss Wilkinson power divider for RF front‐end module applications
Authors: Kangasvieri T. , Hautajärvi I. , Jantunen H. , Vähäkangas J. 
Published: February 2006

AbstractA miniaturized low‐loss Wilkinson power divider was designed and fabricated using standard LTCC technology. Size reduction was implemented by folding the quarter‐wave transmission lines into tightly coupled meander lines. Parameters determining the electrical performance of the divider structure were analyzed using both circuit and full‐wave electromagnetic simulations. Scattering‐parameter measurements correlated very well with the simulations and demonstrated excellent RF performance and manufacturability. Insertion loss of 0.1 dB, return loss of 30 dB, and isolation of 27 dB were measured at the operation frequency. Furthermore, compared to a traditional ring‐type Wilkinson divider, an approximately 67% size reduction was achieved. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 660–663, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21436
A novel microstrip bandpass filter using a dual‐mode square‐ring resonator
Authors: Huang X. D. , Cheng C. H. 
Published: February 2006

AbstractA novel microstrip bandpass filter using a dual‐mode square‐ring resonator is presented in this paper, in which the input/output microstrip lines are arranged under the square‐ring to improve the coupling between the microstrip lines and the square‐ring. The filter has been investigated numerically and experimentally. The measured result shows that the filter has a minimum insertion loss of 1.5 dB inside its passband and the out‐of‐band rejection level of below −26 dB. © 2006 Wiley Periodicals, Inc. Microwave Opt Technical Lett 48:667–669, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21438
A conically coupled waveguide‐to‐coaxial line transition in a reduced‐height waveguide for compact transceivers
Authors: Kim Kang Wook , Woo Dong Sik , Cho Young Ki 
Published: February 2006

AbstractA conically coupled waveguide‐to‐coaxial line transition in a rectangular waveguide whose height is very small compared with that of the standard Ku‐band waveguide is designed and characterized. The input power to the reduced‐height waveguide is coupled to the coaxial line through a metallic cone attached on the waveguide wall. The guiding property of EM waves in the reduced‐height waveguide is found to be drastically different from that in the regular waveguide. The transition structures have been comprehensively analyzed using 3D EM simulators. The measured performance of the fabricated transition shows good agreement with the simulated results over the Ku‐band frequencies, providing broad bandwidth of 5 GHz. The insertion loss of the transition is measured to be about 0.4 dB and the return loss is about 15 dB at 16 GHz. These transitions can be utilized for the construction of broadband compact‐sized transceivers for the input coupling of closely spaced array antennas. © 2006 Wiley Periodicals, Inc. Microwave Opt Technical Lett 48: 669–673, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21439
A spectral‐element time‐domain solution of Maxwell's equations
Authors: Liu Yaxing , Lee Joon‐Ho , Xiao Tian , Liu Qing H. 
Published: February 2006

AbstractA spectral‐element time‐domain (SETD) method based on Gauss–Lobatto–Legendre (GLL) polynomials is presented to solve Maxwell's equations. The proposed SETD method combines the advantages of spectral accuracy with the geometric flexibility of unstructured grids. In addition, a 4th‐order Runge–Kutta method for time integration provides high‐order accuracy and thus reduces the temporal discretization errors. The numerical results demonstrate its spectral accuracy with the order of basis function and show the high efficiency of the proposed method due to its exponential convergence. © 2006 Wiley Periodicals, Inc. Microwave Opt Technical Lett 48: 673–680, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21440