bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compact UWB printed antennas for low frequency applications matched to different transmission lines
Authors: Tourette S. , Fortino N. , Dauvignac J.‐Y. , Kossiavas G. 
Published: March 2007

AbstractA rectangular monopole antenna fed by microstrip, stripline, or coplanar waveguide is studied and enhanced to offer the widest bandwidth with minimum size. A particular attention is focused on ground plans design and coupling between patch and transmission line in order to maintain UWB characteristics and low profile whatever transmission line is used. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1282–1287, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22462
Hairpin bandpass filter with extended upper stopband
Authors: Mondal Priyanka , Chakrabarty Ajay 
Published: March 2007

AbstractIn this article, a novel feed line for harmonic suppression of a slot line hairpin bandpass filter (BPF) is presented. A T‐shaped microstrip feed line is proposed for excitation of the filter. This feeding structure produces frequency‐dependent external coupling that is used for filter upper stopband extension. A fabricated three‐pole filter having centre frequency (f0) of 904 MHz shows 29 dB upper stopband at least up to 6.6f0, while implementing area of the filter is less than 0.65λg × 0.31λg, λg being the guided wavelength at f0. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1463–1464, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22468
Design of ultra‐wide band (UWB) bandpass filter based on defected ground structure
Authors: Yang Guo‐Min , Xiao Gaobiao , Jin Ronghong , Geng Junping , He Wei , Ding Min 
Published: March 2007

AbstractA new structure of ultra‐wide band (UWB) band pass filter is proposed in this letter. The proposed UWB filter consists of a low pass filter and a quasi‐high pass filter. The low pass frequency characteristic is realized with a dumbbell defected ground structure (DGS) array and narrow slots, the corresponding cut‐off frequency is tuned to 10.7 GHz by adjusting sizes of each dumbbell and their spacing. The quasi‐high pass filter consists of two symmetrical inter‐digital capacitors. The cut‐off frequency is about 3.0 GHz. Combining these two structures we obtain a new structure of UWB band pass filter. An experimental UWB filter was fabricated, the measured results show that the insertion loss is less than 1.5 dB throughout the passband of 3.0–10.8 GHz, the variation of group delay less than 0.25 ns in this band, and a wide stopband bandwidth with 20 dB attenuation up‐to 20.0 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1374–1377, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22471
A new capacitive test structure for microwave characterization of biopolymers
Authors: Bartsch Carrie M. , Subramanyam Guru , Grote James , Hopkins Frank K. , Brott Lawrence L. , Naik Rajesh R. 
Published: March 2007

AbstractA new capacitive test structure, containing a parallel plate capacitor with coplanar waveguide feed lines, was used for microwave characterization of biopolymers for the first time. Microwave dielectric properties were obtained for the biopolymers as a function of dc bias and temperature by performing on‐wafer microwave measurements. Dielectric tunability was observed with applied dc bias in the biopolymers tested. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1261–1265, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22474
Polarization reconfigurable CPW‐fed square slot antenna using pin diodes
Authors: Chen Y. B. , Jiao Y. C. , Zhang F. S. 
Published: March 2007

AbstractA novel reconfigurable coplanar waveguide (CPW)‐fed square slot antenna with switchable polarization is presented. The proposed antenna is fed by a CPW, with two T‐shaped metal strips connected to ground plane using pin‐diodes. Switching between right‐hand circular polarization (RHCP) and left‐hand circular polarization (LHCP) is achieved by turning the pin‐diodes on or off. The designed antenna is implemented and measured. It shows that the proposed antenna has broad CP bandwidth in both RHCP and LHCP states. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1233–1236, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22476
Proliferous polymerisation
Authors: Breitenbach J. W. 
Published: March 2007

AbstractProliferous polymerisation makes it possible to produce polymer in the form of particles of an irregular shape. This polymerisation may be carried out in bulk or in aqueous suspension. The mechanism of polymer proliferation is described for various monomers and monomer combinations and examples of proliferous polymerisation are given for a number of cases.Radical formation by chain rupture of polymer molecules is essential for the growth process. Photochemical initiation of proliferous polymerisation demonstrates the high efficiency of the chain rupturing process. Entanglements of macromolecules are shown to contribute to the formation of an insoluble polymer system with a low degree of equilibrium swelling in good solvents.
Construction and application of a low‐speed centrifuge for thermodynamic investigation of macromolecular systems
Authors: Rietveld B. J. 
Published: March 2007

AbstractA description is given of the design, construction and application of a 0–2000 rev/min centrifuge for studying liquid‐liquid phase separations in macromolecular systems at temperatures of 0–200 °C. The concentrations in the phase can be measured with the aid of the complete optical schlieren system of the Model‐E Spinco‐Ultracentrifuge.Owing to the low rotational speed, sedimentation‐velocity and sedimentation‐diffusion equilibrium measurements can be carried out also in solutions containing macromolecules of very high molecular weight.
The structure of poly(di—(p—chlorophenoxy)phosphazine)
Authors: Bishop Sarah M. , Hall Ivan H. 
Published: March 2007

AbstractOrientated, crystalline fibres of poly(di‐(p‐chlorophenoxy)phosphazine) have been prepared and their X‐ray diffraction patterns obtained. From the diffraction data an attempt has been made to deduce the conformation of the molecule. The unit cell is orthorhombic with the following parameters: a = 13.08 ± 0.02 Å, b = 20.23 ± 0.03 Å, c = 4.90 ± 0.01 Å. The space group is P212121 with molecules at the corner and centre of the unit cell pointing in opposite directions. The chain conformation is almost cis‐planar, and the side groups pack so that their oxygen and chlorine atoms lie just above and below the centre of the benzene rings of neighbouring groups. The large side‐groups so dominate the diffraction pattern that, given the inherently poor quality of the intensity data, it was not possible to deduce whether the P‐N and N‐P bonds were of equal or unequal length. It has not therefore been possible to elucidate the nature of the bonding.
Preparation of polyorganosiloxanes from mineral silicates using the method of trimethylsilylation
Authors: Currell B. R. , Midgley H. G. , Seaborne M. A. , Thakur C. P. 
Published: March 2007

AbstractNew polyorganosiloxane glasses, greases and oils have been prepared from certain inorganic mineral silicates. The technique of trimethylsilylation has been applied to a range of minerals with single chain, double chain or sheet silicate anions. In some cases no reaction occurs giving only the unreacted mineral, in others trimethylsilylated products are obtained. Some of these trimethylsilylated products are insoluble powders which gel in organic solvents; others such as the polyorganosiloxane glasses, greases and oils are soluble. The nature of the products is controlled by the structure of the mineral. Important factors are the nature of the cations present, the way in which the silicate anions are packed, and the presence of Al3+ in the silicate anion.
Experimental arguments on the conformation of molecules in molten and glassy polymers
Authors: Hoffmann M. 
Published: March 2007

AbstractIn molten non‐crystallising polymers we find normal random coil conformations of the molecules. This is inferred from the theoretically predicted and experimentally observed relationships between the properties of solutions (relaxational modulus, viscosity, osmotic pressure and specific volume) and melts. It is also derived from the intrinsic viscosities (η) and the diffusion constants of molecules with a very high molecular weight in polymeric solvents (M = 104−105) of the same chemical constitution. Moreover the properties of melts (relaxational modulus, flow curve, viscosity) depend on chemical structure and long chain branching in the manner predicted assuming a random coil conformation.At the glass temperature Tg the conformation resembles that in the melt as the temperature dependence of the conformation at T > Tg shows ((η) in polymeric solvents, diameters of the domains in block copolymers). However, on cooling below Tg an irreversible volume shrinking process may lead to an inhomogeneous distribution of densities and possibly to an extended conformation of molecules in grain boundaries. Experiments show that only strong deviations from random coil conformations decrease the ultimate strength of a glass.
Fracture testing and toughening of epoxy resins
Authors: Meeks Alan C. 
Published: March 2007

AbstractThe tapered cantilever cleavage and the single‐edge‐notch tension fracture toughness tests have been shown to give similar results for several cured epoxy resin systems. Methods for the calculation of fracture energy and critical stress intensity factors are described and discussed. These tests have been used to study the influence of rubber modifiers (“Hycar” CTBN and “Blendex” 311) on the toughness of a conventional epoxy resin (“Epikote” 828) reacted with anhydride curing agents. The modifiers used increase fracture energies and stress intensity factors by factors of approximately 5 and 2 respectively.
Determination of very low concentrations of polyacrylamide and polyethyleneoxide flocculants by nephelometry
Authors: Attia Yosry A. , Rubio Jorge 
Published: March 2007

AbstractA method is described for the analytical determination of low concentrations of polyacrylamide or polyethyleneoxide flocculants in water, in the range 0–10 parts/106. It depends on measuring the turbidity produced by mixing the polymer solution with a dilute solution of tannic acid in the presence of 1 m NaCl. With a sensitive nephelometer, as little as 0.1 parts/106 of flocculant can be detected.
Effects of base nature, base concentration and method of synthesis of titanium polyethers
Authors: Carraher Charles E. , Bajah Samuel T. 
Published: March 2007

AbstractSynthesis of titanium polyethers was effected via four low temperature polycondensation routes, namely the “normal” interfacial, “inverse” interfacial, aqueous solution and organic solution techniques. The greatest yields were obtained through use of the aqueous solution technique while no or small yields resulted from organic solution systems. Both sodium hydroxide and triethylamine proved to be satisfactory bases. No product was formed when base was not added. Results as a function of base concentration are discussed.
Morphological parameters and tensile properties of linear polyethylenes
Authors: Harland William G. , Khadr Mohamed M. , Peters Raymond H. 
Published: March 2007

AbstractLinear polyethylenes of various molecular weights have been moulded into sheet form and cooled under conditions to produce samples differing in lamella fold length and degree of crystallinity. Their load–extension characteristics have been determined and interpreted in terms of a simple model based on a set of crystalline blocks joined by tie bars which, under uniaxial deformation, rupture and transform to a new microfibrillar structure. An explanation of the tensile properties is obtained in terms of the parameters of chain and fold length, degree of crystallinity, number of crystalline units traversed by one molecule, and number of folds per lamella per molecule.
Exploratory experiments on the fast anionic polymerisation of styrene
Authors: Roper Alec N. , Haward Robert N. 
Published: March 2007

AbstractThe limitations in the rates of polymerisation associated with the free radical process do not arise when styrene is polymerised by an anionic catalyst such as butyl lithium. However, if anionic catalysts are directly applied to pure styrene a thermal explosion follows. Some experiments are described in which sufficient low molecular weight polystyrene resin was added to the styrene to prevent boiling and the polymerisation was completed with butyl lithium. In spite of the dilution by low viscosity polymer, average molecular weights were obtained approaching those required for commercial polymer. Although purification criteria would have to be met there seems to be no fundamental obstacle to the development of small, high output polymerisation plants for making polystyrene.
Synthesis and characterization of a bis‐(4‐trifluoromethanesulfonyloxyphenyl)phenylamine monomer and its polymer for light‐emitting applications
Authors: Zengin Huseyin , Zengin Gulay , Topping Chris M. , Smith Dennis W. 
Published: March 2007

AbstractThis study focuses on the preparation, polymerization, characterization, and optical properties of a new bis‐(4‐trifluoromethanesulfonyloxyphenyl)phenylamine monomer. This is the first nitrogen‐containing monomer having nitrogen atoms as bridges between phenyl rings, and it was synthesized in three steps. The polymerization was carried out through the Ni(0)‐catalyzed homocoupling reaction of the bis‐(4‐trifluoromethanesulfonyloxyphenyl)phenylamine compound. The resulting polymer, polybis(paraphenyl)phenylamine, emitted an intense blue color (where λ = 415 nm) upon irradiation by ultraviolet light. The photoluminescence quantum yield was found to be 36% with a long excited‐state lifetime of 3.3 ns. Electrical conductivity data for an HCl‐doped film of the polymer were also examined. This novel polymer is of interest as an organic emitting material for electroluminescent devices. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1860–1867, 2007
High‐molecular‐weight AB‐type benzoxazines as new precursors for high‐performance thermosets
Authors: Agag Tarek , Takeichi Tsutomu 
Published: March 2007

AbstractNovel high‐molecular‐weight polybenzoxazine precursors, namely AB‐type benzoxazine precursors, were synthesized from aminophenols and formaldehyde. Both 1H NMR and IR confirmed the structure of the precursors, indicating the presence of a cyclic benzoxazine structure in the backbone of the precursors. The weight‐average molecular weight was estimated by size exclusion chromatography to be to in the range of 1300–4500. The precursors gave self‐standing thin films when their solutions were cast in dioxane over glass plates and dried, and upon a gradual thermal cure up to 250 °C, they afforded polybenzoxazine films. The viscoelastic analyses showed that the glass transition temperatures of the polybenzoxazine films obtained from these novel precursors were as high as 260–300 °C. Thermogravimetric analysis results indicated that the onset of decomposition and the char yield of the thermosets derived from these AB‐type precursors were higher than those of traditional polybenzoxazine. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1878–1888, 2007.
Prostate‐specific antigen stimulates osteoprotegerin production and inhibits receptor activator of nuclear factor‐KappaB ligand expression by human osteoblasts
Authors: Yonou Hiroyuki , Horiguchi Yutaka , Ohno Yoshio , Namiki Kazunori , Yoshioka Kunihiko , Ohori Makoto , Hatano Tadashi , Tachibana Masaaki 
Published: March 2007

AbstractBACKGROUNDProstate cancer cells produce a large amount of prostate‐specific antigen (PSA), which is widely used as a marker for this cancer. Even though it is widely used in the diagnosis of prostate cancer, many aspects of the pathophysiologic role of PSA in bone metastasis remain obscure. The receptor activator of nuclear factor‐κB ligand (RANKL) is essential for the activation of osteoclasts, while osteoprotegerin (OPG) neutralizes the action of RANKL. Various substances that act on bone have been shown to modulate the production of RANKL and OPG by osteoblasts.METHODSIn this study, we investigated the effect of PSA on the expression of OPG and RANKL mRNA and on protein production in human osteoblast‐like cells.RESULTSAfter addition of PSA and culture for 72 h, OPG mRNA expression and protein secretion by MG‐63 and SaOS‐2 cells showed a concentration‐dependent increase. When osteoblasts were incubated with PSA (100 ng/ml), OPG mRNA expression and protein secretion increased with the passage of time. α1‐antichymotrypsin (ACT), which inactivates the serine protease activity of PSA, inhibited the increase of OPG mRNA expression and protein production in response to PSA, and this effect of PSA was also inhibited by anti‐transforming growth factor‐β antibody.CONCLUSIONSBased on our findings, PSA acts on human osteoblast‐like cells via its own serine protease activity and promotes osteoblast differentiation. In addition, PSA stimulates OPG production and inhibits RANKL expression of osteoblasts, and inhibits bone resorption by osteoclasts, suggesting that it contributes to the characteristic osteoblastic features of bone metastases of prostate cancer. Prostate 67: 840–848, 2007. © 2007 Wiley‐Liss, Inc.
Reformer tubes: Not a commodity
Authors: Webb G. Matthew , Taylor W.K. 
Published: March 2007

AbstractAt the heart of the primary reformer are centrifugally cast alloy steel tubes. These tubes experience the extreme conditions required for steam methane reforming and thus require high quality to achieve their expected design life. The tube designs need to balance heat transfer rates, optimize catalyst volumes and minimize thermal stresses, while not compromising the tube life expectancy. Centrifugally cast heat resistant alloys have proven themselves as the ideal material for this service.Individual cast tubes are custom made so it is important that the buyer be aware of the manufacturing methods of these products: to be aware of potential pitfalls and to appropriately specify the inspection and quality assurance requirements. Each tube segment is cast individually from a small heat, resulting in a unique chemical composition. Subsequent boring, machining, welding, and inspection operations are important to ensure the quality of the tube segments and the final reformer tube assembly. The reformer tube manufacturing process, including casting, machining and fabrication, is presented with the typical inspection operation.Some defects in the design and fabrication are described. These defects have caused ammonia and syngas plant shutdowns at a great expense to operating companies. Such defects can be avoided at the design or specification stage or during quality control tests. This paper describes how to avoid such defects. © 2007 American Institute of Chemical Engineers Process Saf Prog, 2007.
Biophysical properties of a synthetic transit peptide from wheat chloroplast ribulose 1,5‐bisphosphate carboxylase
Authors: Ambroggio Ernesto E. , Austen Brian , Fidelio Gerardo D. 
Published: March 2007

AbstractThe surface properties of pure RuBisCo transit peptide (RTP) and its interaction with zwitterionic, anionic phospholipids and chloroplast lipids were studied by using the Langmuir monolayer technique. Pure RTP is able to form insoluble films and the observed surface parameters are compatible with an α‐helix perpendicular to the interface. The α‐helix structure tendency was also observed by using transmission FT‐IR spectroscopy in bulk system of a membrane mimicking environment (SDS). On the other hand, RTP adopts an unordered structure in either aqueous free interface or in the presence of vesicles composed of a zwitterionic phospholipid (POPC). Monolayer studies show that in peptide/lipid mixed monolayers, RTP shows no interaction with zwitterionic phospholipids, regardless of their physical state. Also, with the anionic POPG at high peptide ratios RTP retains its individual surface properties and behaves as an immiscible component of the peptide/lipid mixed interface. This behaviour was also observed when the mixed films were composed by RTP and the typical chloroplast lipids MGDG or DGDG (mono‐ and di‐galactosyldiacylglycerol). Conversely, RTP establishes a particular interaction with phosphatidylglycerol and cardiolipin at low peptide to lipid area covered relation. This interaction takes place with an increase in surface stability and a reduction in peptide molecular area (intermolecular interaction). Data suggest a dynamic membrane modulation by which the peptide fine‐tunes its membrane orientation and its lateral stability, depending on the quality (lipid composition) of the interface. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
α,β‐Dehydrophenylalanine containing cecropin–melittin hybrid peptides: conformation and activity
Authors: Mathur Puniti , Jagannathan N. R. , Chauhan V. S. 
Published: March 2007

AbstractSynthesis and conformational studies of a cecropin–melittin hybrid pentadecapeptide CA(1–7)MEL(2–9), and its three α, β‐dehydrophenylalanine (ΔPhe) containing analogs in water‐TFE mixtures are described. ΔPhe is placed at strategic positions in order to preserve the amphipathicity of the molecule. The wild type CAMEL0 and its three analogs, containing one, two and three ΔPhe residues namely CAMELΔPhe1, CAMELΔPhe2 and CAMELΔPhe3 respectively were synthesized in solid phase and their conformation determined by CD and NMR. CAMELΔPhe2 and CAMELΔPhe3 peptides exhibit the presence of 310‐helix and β‐turns in the former and only turns in the latter. CAMELΔPhe1 peptide was found to have a largely extended conformation. Antibacterial and hemolytic activities of the peptides were also evaluated. CAMELΔPhe2 peptide is maximally potent against both Staphylococcus aureus ATCC 259230 and Escherichia coli ATCC 11303. CAMELΔPhe1 with a single ΔPhe at the center shows minimal hemolysis. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Combinatorial investigation of nanostructures formed in a titanium dioxide based nanocomposite film on top of fluor‐doped tin oxide layers
Authors: Müller‐Buschbaum P. , Perlich J. , Abul Kashem M. M. , Schulz L. , Roth S. V. , Cheng Y. J. , Gutmann J. S. 
Published: March 2007

AbstractNanostructures formed in a titanium dioxide (TiO2)–poly(styrene)‐block‐poly(ethyleneoxide) nanocomposite film on top of fluor‐doped tin oxide (FTO) layers are investigated. The combinatorial approach is based on probing a wedge‐shaped FTO‐gradient with grazing incidence small angle X‐ray scattering (GISAXS) in combination with a moderate micro‐focus X‐ray beam. The characteristic lateral length is given by adjacent nanowire‐shaped TiO2 regions. It decreases from 200 nm on the thick FTO layer to 90 nm on the bare glass surface.magnified imageSketch of the FTO gradient coated with a nanocomposite layer probed in the combinatorial approach.(© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)