bluuebunny/crossref_metadata_2025 huggingface dataset:
Super‐hyper singularity treatment for solving 3D electric field integral equations
Authors: Tong Mei Song , Chew Weng Cho
Published: March 2007

The super‐hyper singularity treatment is developed for solving three‐dimensional (3D) electric field integral equations (EFIE). EFIE usually takes two forms: one of which includes a super‐hyper singular kernel generated by the double gradient of the Green's function. So far, there is no way to evaluate these super‐hyper singular integrals needed for constructing the pertinent matrix equation. We apply the series expansion of the Green's function to the super‐hyper singular kernel and derive closed‐form expressions for their evaluations in the Cauchy principal‐value sense. The derivation is based on the constant current approximation over a flat triangle patch, but it can be extended easily to higher‐order approximations of the current. The scheme can be used to accurately calculate the near and self interaction terms in the impedance matrix for the method of moments (MoM), Nyström method or boundary element method (BEM). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1383–1388, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22443
Inverse formula of coupled‐striplines by synthetic asymptote
Authors: Wang Ke , Shi Xiangquan , Tang Wanchun
Published: March 2007

The inverse formula for the ratio of the elliptic integral of the first kind is obtained by synthetic asymptote in this paper. Then calculate the relative dimensions of the structures of broadside‐coupled and edge‐coupled striplines. The average errors of the characteristic impedance for the two cases are less than 1.5%. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1309–1312, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22446
Retro‐directive array with beam steering capability, made by coupled, self‐oscillating mixers
Authors: Christodoulou Michail G. , Chrissoulidis Dimitrios P.
Published: March 2007

A novel, phase‐conjugator array for active, retro‐directive operation has been made by use of three dual‐gate, self‐oscillating mixers (SOM's), mutually locked by use of 6 dB hybrid couplers. The coupling network incorporates the load of the oscillators. Reduced LO penetration has been achieved at the RF and IF and ports by trapping the LO signal within the dc bias lines of each SOM. Injection of two external signals at the LO frequency, each at a marginal SOM, with phase difference ΔΦ between them, allows for retransmission at angles other than the angle of arrival of the incident signal. Measured results are presented for a retro‐directive array designed for nominal operation at 900 MHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1303–1309, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22447
Wideband fractal printed monopole antennas
Authors: Lee Yi‐Chieh , Sun Jwo‐Shiun , Lin Syuan‐Ci
Published: March 2007

Study of CPW‐fed monopole antenna with circular and rectangular fractal shape radiator element is proposed. By using fractal slot, new design antennas have the wide measured return loss bandwidth. In addition, the omnidirectional radiation patterns of the design antennas covering the entire frequency range have been obtained. Several properties of the antennas such as impedance bandwidth, radiation patterns, and gain have been investigated numerically and experimentally in detail. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1267–1272, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22448
All‐optical mm‐wave generation by using direct‐modulation DFB laser and external modulator
Authors: Chen Lin , Pi Yazhi , Wen Hong , Wen Shuangchun
Published: March 2007

We proposed and experimentally demonstrated a novel method of optical mm‐wave generation using only one Mach‐Zehnder modulator and a direct‐modulator, based on the method of optical carrier suppression. Using this proposed method, the 2.5 Gb/s data channel was successfully transmitted over 20 km for downstream with less than 1‐dB power penalty. Therefore, the system configure of mm‐wave generation can be further simplified and be more cost effective. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1265–1267, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22449
Nonlinear actuation model for lateral electrostatically‐actuated DC‐contact RF MEMS series switches
Authors: Lázaro A. , Girbau D. , Pradell L. , Nebot A.
Published: March 2007

In this work, a nonlinear model to predict actuation characteristics in lateral electrostatically‐actuated DC‐contact MEMS switches is proposed. In this case a parallel‐plate approximation cannot be applied. The model is based on the equilibrium equation for an elastic beam. It is demonstrated that the contribution of fringing fields is essential. The model relies on finite‐difference discretization of the structures, applying boundary conditions and is solved with a Gauss‐Seidel relaxation iteration scheme. Its usefulness is demonstrated in a series MEMS switch with lateral interdigital electrostatic actuation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1238–1241, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22450
Gap coupled rectangular microstrip antennas for dual and triple frequency operation
Authors: Ray K. P. , Sevani V. , Kulkarni R. K.
Published: March 2007

A rectangular microstrip antenna is gradually divided into equal smaller elements along the width, and lengths of these smaller strips are varied to increase the separation between the resonances to obtain dual and triple frequency operation. Likewise, configurations consisting a maximum of five strips have been investigated. For configurations with two strips only dual frequency operation has been obtained, whereas for configurations with more than two strips both dual and triple frequency operation has been obtained. With increase in number of elements, the separation between different resonances is more and the radiation pattern is also similar in two frequency bands. Experiments have been performed and the results are in agreement with the simulations. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1480–1486, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22452
A CMOS LC‐tank frequency divider with 3D helical inductors
Authors: Jang Sheng‐Lyang , Lee Shao‐hua , Wu Yen‐Ruei
Published: March 2007

The design of a frequency divider (FD) employing 3D helical inductors fabricated in the 0.18‐μm 1P6M CMOS technology is reported. The LC resonators consist of two 3D helical inductors and varactors. The aim of using 3D inductor is to reduce chip size, the inductance of inductor is designed to be 2 nH, and the size of the inductor is 155 × 155 μm2. The divide‐by‐2 LC‐tank injection locked FD is performed by adding an injection nMOS between the differential outputs of the divider with the structure of cross‐coupled n‐core VCO that contains a tapped LC resonator. The measurement results show that at the supply voltage of 1 V, the divider free‐running frequency is tunable from 2.496 to 2.04 GHz, and at the incident power of 0 dBm the locking range is about 1.31 GHz (30%), from the incident frequency 3.84–5.12 GHz. The core power consumption is 2.59 mW. The die area is 0.664 × 0.731 mm2. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1477–1480, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22453
A high‐efficiency class‐E power amplifier using SiC MESFET
Authors: Lee Yong‐Sub , Jeong Yoon‐Ha
Published: March 2007

This article reports a high efficiency class‐E power amplifier using a SiC MESFET, which is designed and tested at 2.14 GHz. To improve output power and efficiency by suppressing harmonic powers, an output matching circuit using the transmission lines is used. From measured results for a single tone, the harmonic power levels are maintained below −58 dBc at a whole output power level. The peak power‐added efficiency of 72.3% with a power gain of 10.27 dB is achieved at an output power of 40.27 dBm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1447–1449, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22455
Novel defected ground structure element with triple transmission zeros and its application for multispurious suppression of microstrip parallel‐coupled‐line bandpass filter
Authors: Ting Sio‐Weng , Tam Kam‐Weng , Martins Rui
Published: March 2007

A novel compact defected ground structure (DGS) element with triple transmission zeros is proposed. The zeros can be tuned individually by the DGS geometry and the overall etched area is kept as compact as that of the conventional structure with single zero. The traditional microstrip parallel‐coupled‐line bandpass filter cascading this new element, not only achieves the multispurious suppression but also its basic design formulation is retained. A prototype DGS filter was designed and tested to validate its performance. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1409–1412, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22457
1.9‐GHz low noise amplifier using high‐linearity and low‐noise composite‐channel HEMTs
Authors: Cheng Zhiqun , Cai Yong , Liu Jie , Zhou Yugang , Lau Kei May , Chen Kevin J.
Published: March 2007

Monolithic integrated 1.9‐GHz low noise amplifier (LNA) using 1 μm‐gate high‐linearity and low noise composite‐channel Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMT (CC‐HEMT) device is designed, fabricated and characterized. The LNA exhibits a noise figure of 1.3 dB, an associated gain of 17 dB, an input return loss of −5.5 dB and an output return loss of −15 dB at 1.9 GHz. The IIP3 and IIP5 of the LNA are 15 and 12 dBm at 1.9 GHz. The LNA with 1 × 100 μm2 device shows high‐dynamic range with decent gain and noise figure. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1360–1362, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22459
Space‐mapped neuro‐fuzzy optimization for microwave device modeling
Authors: Hinojosa J. , Doménech‐Asensi G.
Published: March 2007

Four modeling methods of microwave devices using multiple neuro‐fuzzy inference systems (MANFIS) based on space‐mapping (SM) approach are presented. In contrast with previous works using conventional mathematical tools and artificial neural networks, the proposed SM‐based neuro‐fuzzy modeling methods can construct nonlinear multidimensional mapping functions based on both human knowledge in the form of fuzzy if–then rules easy to understand by human beings and stipulated input–output data pairs, without employing precise quantitative analyzes. Optimization by microgenetic algorithm is used to find nonlinear multidimensional mapping functions for the modeling methods that present a singular system. These methods are applied to a shielded microstrip line and the obtained models are discussed. These space‐mapped neuro‐fuzzy models could be integrated in a toolbox of any commercially available computer‐aided design tools for radio frequency/microwave circuits. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1328–1334, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22460
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

A 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

In 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

A 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

A 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

A 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

Proliferous 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

A 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

Orientated, 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

New 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

In 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

The 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

A 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

Synthesis 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

Linear 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

The 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

This 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

Novel 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

BACKGROUND

Prostate 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.

METHODS

In 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.

RESULTS

After 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.

CONCLUSIONS

Based 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

At 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

The 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

Synthesis 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

Nanostructures 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 image

Sketch of the FTO gradient coated with a nanocomposite layer probed in the combinatorial approach.

(© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of tetracycline antibiotics in cow's milk by liquid chromatography/tandem mass spectrometry
Authors: De Ruyck Hendrik , De Ridder Herman
Published: March 2007

A liquid chromatographic/tandem mass spectrometric (LC/MS/MS) multiresidue method for the simultaneous quantitative determination of oxytetracycline, 4‐epi‐oxytetracycline, tetracycline, 4‐epi‐tetracycline, chlortetracycline, 4‐epi‐chlortetracycline and doxycycline in milk has been developed. An extraction procedure consisting of a liquid extraction of the milk samples with trichloroacetic acid was performed. The extract was centrifuged and the supernatant was filtered. Solid‐phase extraction (SPE) with an OASIS HLB SPE column was used to clean up the sample extracts. The samples were analysed by LC/MS/MS. The LC separation was performed on a reversed‐phase C18 column using gradient elution with a mobile phase consisting of water and a mixture of methanol/acetonitrile. The tetracycline analytes were detected with a quadrupole mass spectrometer using positive ion electrospray ionisation. The confirmatory method has acceptable detection limits and the different tetracyclines can be detected at a residue concentration between 5 and 20 µg/L. The method is validated according to the European requirements for veterinary drug residues and all determined parameters were found to conform to the criteria. The recovery values ranged from 90.4 to 101.2% with relative standard deviations (RSDs) no larger than 9.7%. The overall or between‐day precision of the analytical assay determined as repeatability at several residue concentrations and expressed as RSD ranged from 3.3 to 10%. This analytical assay is a useful tool within the Belgian monitoring programme for confirmation of samples which have been positively screened for residues of tetracyclines in raw farm cow's milk. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis of nitrogen‐containing compounds using chromium Fischer carbene complexes
Authors: Kagoshima Hirotaka , Fuchibe Kohei , Akiyama Takahiko
Published: March 2007

Synthetic utility of the Fischer‐type carbene complexes of chromium for the preparation of nitrogen‐containing compounds is demonstrated. Alkoxy carbene complexes reacted with imines to give (optically active) 3‐pyrrolines and β‐methoxy allylic amine derivatives in good yields. The amino carbene complexes reacted with α,β‐unsaturated aldehydes to give substituted pyrroles in good yields. © 2007 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 7: 104–114; 2007: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20106
Phenacyl onium salt photoinitiators: synthesis, photolysis, and applications
Authors: Yagci Yusuf , Durmaz Yasemin Yuksel , Aydogan Binnur
Published: March 2007

Onium salts, namely sulfonium, phosphonium, ammonium, and pyridinium salts containing phenacyl group are photoinitiators appropriate for the polymerization of monomers such as oxiranes and vinyl ethers, which are not polymerizable by a free‐radical mechanism. The initiation is accomplished by direct or indirect (sensitized) photolysis of the salts. Depending on the type of the salt, the direct photoinitiation of cationic polymerization involves reversible or irreversible processes. The photolysis of phenacylsulfonium compounds proceeds by a reversible process, while the other types undergo irreversible photolysis leading to complete fragmentation of the photoinitiator. An additionally useful tool, namely photosensitized generation of initiating species enlarges the versatility of these salts as photoinitiators. Photoinitiated free‐radical and zwitterionic polymerizations by using phenacyl‐type salts are also addressed. Keto‐enol tautomerization of phenacyl pyridinium salts is discussed. Moreover, an interesting application concerning in situ synthesis of clay‐poly(methyl methacrylate) nanocomposites with the aid of the phenacyl anilinium salt‐based photolymerization technique is noted. © 2007 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 7: 78–90; 2007: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20110
3. Management of urinary tract infections in men
Authors: Harper Matthew , Fowlis George
Published: March 2007

Urinary tract infection in the adult male is rare and usually indicates underlying urological pathology. The aim in primary care is to make a prompt and accurate diagnosis, to initiate appropriate antibiotic treatment and to start the process of urinary tract investigation, which may well culminate in a urological referral. In this article, the authors provide a practical stepwise guide for those managing urinary tract infections in adolescent and adult males in the community. Copyright © 2007 Wiley Interface Ltd
Integral centrifuges for olive oil extraction. The qualitative characteristics of products
Authors: Ranalli Alfonso , Angerosa Franca
Published: March 2007

Oil extraction experiments with three olive varieties (Coratina, Nebbio, and Grossa di Cassano) were carried out to compare the two‐phase centrifugal decanter with conventional three‐phase equipment. The results showed that the two‐phase centrifugal extractor renders better qualitative characteristics in the oils, which were comparable to pressed or filtered oils. The two‐phase decanter product exhibited higher contents of polyphenols,ortho‐diphenols, hydroxytyrosol, tocopherols,trans‐2‐hexenal and total aromatic volatile substances. Furthermore, the oils received a higher sensorial score and were characterized by higher values of oxidative stability and campersterol/stigmasterol ratio; lower values of turbidity, alcohol index and chromatic indices; lower content of pigments, steroid hydrocarbons, stigmastatriene, waxes and aliphatic and triterpenic alcohols.
A new industrial process for extracting cocoa butter and xanthines with supercritical carbon dioxide
Authors: Li Shufen , Hartland Stanley
Published: March 2007

This research explores the feasibility of extracting cocoa butter and xanthines (theobromine and caffeine) from cocoa beans with supercritical CO2. It is difficult to carry out the extraction with CO2 alone in the temperature range 40–90°C at pressures between 80 to 300 bar. However, the addition of a polar cosolvent, such as ethanol, greatly enhances solubilities, especially that of cocoa butter. Based on experimental investigations and theoretical inference, the design of a potential industrial process for extracting cocoa butter and xanthines is proposed, in which ethanol is used as cosolvent, and distillation is used to separate and regenerate ethanol. The pressure required is much less than that for CO2 alone as specified in the patent literature.
Enzyme‐assisted extraction of shea fat: Evidence from light microscopy on the degradative effects of enzyme treatment on cells of shea kernel meal
Authors: Tano‐Debrah Kwaku , Yoshimura Yukinori , Ohta Yoshiyuki
Published: March 2007

A light‐microscopic study on enzyme‐treated sliced shea kernels was done to investigate the principles involved in enzyme‐assisted shea fat extraction. The raw, ellipsoidally shaped kernels, measuring 1.3 to 2.0 cm, were crosssectioned into slices of about 2‐mm thickness, which were then dissected into four or six pieces. These samples were treated with or without enzymes for predetermined periods, fixed and processed for paraffin sections (5 μm). Sections were stained with periodic acid‐Schiff base (PAS) or Coomassie blue (CB) to localize the complex polysaccharides and proteins, respectively. The cells of the enzyme‐treated samples showed distinct degradation and a high loss of cellular integrity. PAS reaction and CB staining of these cells confirmed high loss of cellular materials compared to control samples. This was also reflected in the increases of the soluble protein and free sugar contents of the effluent water collected from samples after treatment. The oilseed materials during preextraction. They thus support the principle of using enzyme treatments to improve fat yield in solvent extraction systems, as has been reported by various investigators.
Formulation and optimization of sucrose polyester physical properties by mixture response surface methodology
Authors: Shieh Chwen‐Jen , Akoh Casimir C. , Koehler Philip E.
Published: March 2007

The physical properties of sucrose polyester (SPE), prepared from different composite blends of fatty acid methyl esters (FAME) of safflower oil, palm oil, and peanut oil, were evaluated by mixture response surface methodology. Optimum combinations of fatty, acids to achieve specific physical properties of SPE were determined. The SPE most similar in physical properties to peanut oil was obtained with a 55:45 molar ratio of mixed FAME from safflower oil and peanut oil. The physical properties of SPE were significantly affected by the degree of saturation and the average chainlength of their composite fatty acids.
Effects of raw materials and preparation methods of catalysts on the selective hydrogenation of ethyl phenylacetate
Authors: Ishii Kazuaki , Mizukami Fujio , Niwa Shu‐ichi , Toba Makoto , Ushijima Hirobumi , Sato Takami
Published: March 2007

A ruthenium/tin/alumina catalyst was found to hydrogenate ethyl phenylacetate to 2‐phenylethanol selectively with a high yield. The optimum atomic ratio of ruthenium to tin was 1∶2, and the optimum metal content was about 5 and 11.75 wt% for ruthenium and tin, respectively. The raw materials of the catalyst had a significant effect on the conversion and selectivity in the catalytic hydrogenation. Chloride had a negative effect on catalytic activity. Washing the catalysts, which were prepared from chloride materials, with distilled water or alkali solution had a positive effect upon catalyst activity. The catalyst prepared from chloride‐free raw materials performed the best, and the impregnation catalyst has a higher yield than the solgel catalyst, suggesting that impregnation is a suitable procedure for this reaction.
Identification of adulterants in olive oils
Authors: Wesley I. J. , Pacheco F. , McGill A. E. J.
Published: March 2007

The application of discriminant analysis for identifying and quantifying adulterants in extra virgin olive oils is presented. Three adulterants were used (sunflower oil, rapessed oil, and soybean oil) and were present in the range 5–95%. Near‐infrared spectroscopy and principal components analysis were used to develop a discriminant analysis equation that could identify correctly the type of seed oil present in extra virgin olive oil in 90% of cases. Partial least squares analysis was used to develop a calibration equation that could predict the level of adulteration. Cross validation suggested that it was possible to measure the level of adulteration to an accuracy of ±0.9%. External validation of the derived calibation equation gave a standard error of performance of ±2.77%.
Determination of iodine value without chlorinated solvents
Authors: Mozayeni F. , Szajer G. , Walters M.
Published: March 2007

A modified determination of iodine value in fats, fatty acids, and fatty acid derivatives is reported. The described procedures, visual and potentiometric, have wide applicability and generate less solvent waste. These analytical procedures are based on a nonchlorinated solvent system. The performance of the new procedures was evaluated in a multiple‐laboratory study.
Separation of crude palm oil components by semipreparative supercritical fluid chromatography
Authors: Choo Yuen May , Ma Ah Ngan , Yahaya Hawari , Yamauchi Y. , Bounoshita M. , Saito M.
Published: March 2007

Successful separation of triglycerides, diglycerides, free fatty acids, carotenes, tocopherol, and tocotrienols from crude palm oil has been achieved by supercritical fluid chromatography (SFC) with a combination of a C18 and a silica gel column. The separation was carried out by the programmed extraction elution method. Free fatty acids were separated into five components by gas‐liquid chromatography; tocopherol and tocotrienols were also separated into four components by SFC analysis, and the pure fractionated carotenes were obtained by preparative SFC. Thus, by using supercritical fluid chromatography, crude palm oil components can be separated and fractionated, based on differences in their functional groups.
Soy hull carbon as an adsorbent of minor crude soy oil components
Authors: Proctor A. , Harris C. D.
Published: March 2007

A carbon adsorbent was prepared from soy hulls. The adsorbent was used in a laboratory study to examine its performance under commercial soy oil adsorption bleaching conditions. Phospholipids, peroxides, and free fatty acids were effectively removed from the soy oil with little effect on carotenoid content. There may be competitive adsorption between oil components, the rank of the affinity of oil components for soy carbon was phospholipid>peroxides>free fatty acid>lutein.