bluuebunny/crossref_metadata_2025 huggingface dataset:
Lupane Pentacyclic Triterpenes Isolated from Stems and Branches of Maytenus imbricata (Celastraceae)
Authors: Ribeiro de Souza e Silva Silvia , de Fátima Silva Gracia Divina , de Almeida Barbosa Luca Cláudio , Duarte Lucienir Pains , Filho Sidney Augusto Vieira
Published: May 2005

Four lupane pentacyclic triterpenes were isolated from the hexane extract of stems and branches of Maytenus imbricata Mart. ex Reissek: 3‐oxolup‐20(30)‐en‐29‐al (1), 30‐hydroxylup‐20(29)‐en‐3‐one (2), (11α)‐11‐hydroxylup‐20(29)‐en‐3‐one (3), and (3β)‐lup‐20(30)‐ene‐3,29‐diol (4). The structural identification of 1–4 was achieved by 1H‐ and 13C‐NMR techniques, including 2D experiments (HSQC, HMBC, and NOESY).
A Macrobicyclic Calix[6]arene Phosphocine: Conformational Studies Involving High‐Resolution NMR Analysis and Molecular Modeling
Authors: Regnouf‐de‐Vains Jean‐Bernard , Cartier Alain , Fenet Bernard , Pellet‐Rostaing Stéphane
Published: May 2005

The solution structure of the phosphorylated hexa(tert‐butyl)calix[6]arene 1a was elucidated through a series of high‐resolution, one‐ and two‐dimensional 1H‐ and 13C‐NMR experiments, in combination with 31P‐NMR measurements. The NMR results were cross‐checked and refined with partial structural information obtained from a poorly resolved X‐ray crystal‐structure analysis. The latter, that could not be upgraded due to the low quality of the crystals and due to strong thermal motions, confirmed that 1a was a racemate in which two adjacent phenol units are bridged by a mono‐ethyl phosphate moiety, generating a macrocyclic dibenzo[1,3,2]dioxaphosphocine substructure, while the four residual aromatic rings bear regular diethyl phosphate arms. One of these rings is inverted, generating the main asymmetry in the molecule, which gives rise to the racemic nature of the macrobicycle. The two enantiomers, however, do not interconvert on the NMR time scale in solution and resemble the solid‐state structure, as expected from the steric hindrance due to the pendant phosphoesters and the high intramolecular tension due to the presence of the phosphocine substructure. The most‐probable conformation of 1a in solution was determined, starting from the NMR and X‐ray data, by means of semi‐empirical PM3 calculations with the GEOMOS program, including an unprecedented large number of 232 atoms.
Six New Triterpene Saponins with a 21,23‐Lactone Skeleton from Gynostemma pentaphyllum
Authors: Yin Feng , Hu Li‐Hong
Published: May 2005

The six new triterpene saponins 1–6 with a 21,23‐lactone skeleton were isolated from the MeOH extract of the aerial parts of Gynostemma pentaphyllum. Their structures were elucidated by 1D‐ and 2D‐NMR‐spectra interpretation as well as by chemical degradation.
Syntheses and Crystal Structures of Four New Ammoniates with Heptaarsenide (As$\rm{_{7}^{3-}}$) Anions
Authors: Hanauer Tobias , Grothe Michael , Reil Markus , Korber Nikolaus
Published: May 2005

The syntheses and X‐ray single‐crystal low‐temperature structures of the four new ammoniates [Li(NH3)4]3As7⋅NH3 (1), [Rb(18‐crown‐6)]3As7⋅8 NH3 (2), Cs3As7⋅6 NH3 (3), and (Ph4P)2CsAs7⋅5 NH3 (4) are reported. The compounds were obtained by either direct reduction of As with Li/Cs in liquid NH3, solvation of Cs4As6/Rb4As6 in liquid NH3, or by extraction of solid Cs3As7. While compound 1 contains isolated As$\rm{_{7}^{3-}}$ polyanions, AsM contacts (M=Na−Cs) lead to neutral [Rb(18‐crown‐6)]3As7 units in 2, a three‐dimensional, extended network in 3, and one‐dimensional, infinite $\rm{_{\infty }^{1}}$[CsAs7]2− chains in 4, respectively.
Three New Highly Oxygenated Diterpenoids from Excoecaria cochinchinensis Lour.
Authors: Yang Jing‐Hua , Luo Shi‐De , Zhao Jing‐Feng , Wang Yun‐song , Huang Rong , Zhang Hong‐Bin , Li Liang
Published: May 2005

Chemical examination of the AcOEt extract of the leaves and twigs of Excoecaria cochinchinensis Lour. collected from Xishuangbanna resulted in the isolation of the three new highly oxygenated diterpenoids 1–3. The structures of the new diterpenoids were elucidated by a study of their physical and spectra data as (2β,3β,5α,6α)‐2,3‐bis(acetyloxy)‐8,13‐epoxy‐6,9‐dihydroxylabd‐14‐en‐11‐one (=excolabdone A; 1), (1α,5α,6β,7β)‐1,6‐bis(acetyloxy)‐8,13‐epoxy‐7,9‐dihydroxylabd‐14‐en‐11‐one (=excolabdone B; 2), and (1α,5α,6β,7β)‐6‐(acetyloxy)‐8,13‐epoxy‐1,7,9‐trihydroxylabd‐14‐en‐11‐one (=excolabdone C; 3).
A Novel Intramolecular Photocyclization of N‐(2‐Bromoalkanoyl) Derivatives of 2‐Acylanilines via 1,8‐Hydrogen Abstraction
Authors: Nishio Takehiko , Koyama Hiroyuki , Sasaki Daigo , Sakamoto Masami
Published: May 2005

The photochemical reactions of different N‐(2‐acylphenyl)‐2‐bromo‐2‐methylpropanamides have been investigated. Irradiation of the N‐unsubstituted anilides 1a–1c gave the corresponding dehydrobromination, cyclization, and bromo‐migration products 2, 3, and 4, respectively (Table 1). Irradiation of the N‐alkyl anilides 1e–1g afforded the corresponding deacylation and cyclization products 5 and 6, respectively, whereas irradiation of the N‐alkyl anilides 1i–1k, carrying 2‐benzoyl groups on the aromatic rings, afforded the unexpected tricyclic lactams 7 (besides 2, 5, and 6). The formation of the cyclization products 6 could be rationalized in terms of an electrocyclic ring closure of the 6π‐electron‐conjugated enamides 2 produced by dehydrobromination of 1, followed by thermal 1,5‐acyl migration (Path B in the Scheme). The formation of the bridged lactams 7 probably follows a mechanism involving the 1,7‐diradical 8 generated by ζ‐H‐abstraction (1,8‐H transfer) by an excited acyl O‐atom (Path A).
Forbidden subgraphs and bounds on the size of a maximum matching
Authors: Plummer Michael D. , Saito Akira
Published: May 2005

Let K1,n denote the star on n + 1 vertices; that is, K1,n is the complete bipartite graph having one vertex in the first vertex class of its bipartition and n in the second. The special graph K1,3, called the claw, has received much attention in the literature. In particular, a graph G is said to be claw‐free if G possesses no K1,3 as an induced subgraph. A well‐known theorem of Sumner and, independently, Las Vergnas says that every connected even claw‐free graph contains a perfect matching. (Later, Jünger, Pulleyblank, and Reinelt proved that if G is connected, claw‐free, and odd, then G must contain a near‐perfect matching.) More generally, Sumner proved that if G is K1,n‐free, (n − 1)‐connected, and even, then G must contain a perfect matching. In this paper, we extend these results in several ways. First, we show that if G is a k‐connected K1,n‐free graph on p vertices, then def(G) is bounded above by a certain function of k,n, and p, where def(G) is the deficiency of G. (The deficiency of a graph measures how far a maximum matching is from being perfect; that is, def (G) = p − 2ν(G), where ν(G) is the size of any maximum matching in G.) We then provide examples to show that this upper bound is sharp for each value of k and n. We then prove a result that is a type of converse to the above theorem in the following sense. Suppose that H is a connected graph and suppose that there exist constants α and β, 0 ≤ α < 1, such that every k‐connected H‐free graph G of sufficiently large order satisfies (G) ≤ α|V(G)| + β. Then the excluded subgraph H must be a K1,n, where n is bounded above by a certain function of α and k. © 2005 Wiley Periodicals, Inc. J Graph Theory
Developmental changes in Trichoderma viride enzymes abundant in conidia and the light‐induced conidiation signalling pathway
Authors: Pokorný Richard , Vargovič Peter , Hölker Udo , Janssen Martina , Bend Jutta , Hudecová Daniela , Varečka L'udovít
Published: May 2005

The expression of glutamic acid decarboxylase gene and the laccase activity were measured during the development of surface‐cultivated Trichoderma viride mycelia in order to examine their up‐regulation by light. The results show that the changes in activity of GAD induced by light observed previously are caused by transcriptional regulation of gad gene expression in both submerged mycelia and aerial mycelia after photoinduction. The expression of tga gene encoding a T. viride Gα protein was found not to be up‐regulated by light and was also present in the non‐conidiating mutant of T. viride suggesting that this protein is not involved in the regulation of conidiation in this fungus, or that it plays a role is in later stages of conidia development. The activity of laccase was also not light‐inducible and may be related to the maturation of conidia. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of an arbuscular mycorrhizal fungus, Glomus mosseae, and a rock‐phosphate‐solubilizing fungus, Penicillium thomii, on Mentha piperita growth in a soilless medium
Authors: Cabello Marta , Irrazabal Gabriela , Bucsinszky Ana Maria , Saparrat Mario , Schalamuk Santiago
Published: May 2005

Rock phosphate effect on English mint (Mentha piperita L.) grown on steamed perlite:vermiculite (1:1, v:v) substrate, with and without rock phosphate, was evaluated in greenhouse experiments. Five treatments were carried out by inoculation with an arbuscular mycorrhizal fungus Glomus mosseae and a phosphorus solubilizing microorganism Penicillium thomii. Plant aerial biomass, phosphorus concentration in plant tissue, and P available in the substrate, were evaluated upon two harvests. After the first harvest, plant aerial biomass did not show significant differences between treatments using rock phosphate as fertilizer, although P content in plants inoculated with P. thomii was higher. The second harvest revealed a higher biomass and plant tissue P content in treatments inoculated with G. mosseae. P. thomii increased P available in the substrate, whereas in the absence of G. mosseae, it did not enhance plant tissue P content. Mycorrhizal colonization was not affected by P. thomii. Microbial inoculation effect on English mint growth was also evaluated. The microbial effect was positive in all treatments when compared with the control without rock phosphate. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Production of 2‐methylisoborneol by Streptomyces violaceusniger and its transformation by selected species of Pseudomonas
Authors: Saadoun Ismail
Published: May 2005

The effect of glucose, glycerol and yeast‐extract (YE) on 2‐methylisoborneol (MIB) production by Streptomyces violaceusniger (C4–S strain) was determined. Glycerol as a sole carbon source promoted MIB production was maximum concentration (40.65 µg/l) after 10 days incubation, while glucose favored biomass production. Increasing YE concentration from 0.1 to 1% (W/V) repressed MIB production with 62 and 83% reduction after 10 and 14 days, respectively. Transformation of this odorous compound was investigated using seven different Pseudomonas species. Action of the different Pseudomonas spp. on the C4–S extract was followed at 1 hour, 2 hours, 6 hours and 12 hours. Pseudomonas spp. 1, 2, 3 and 5 indicated a positive reaction; however, Pseudomonas spp. 4, 6 and 7 showed no effect. These data suggest that 2‐methylisoborneol can be transformed by Pseudomonas spp. and the test adopted by this study can be applied for screening organisms for their ability to transform MIB. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hyperbranching induced by cold‐shock or snow‐flake mutation in Neurospora crassa is prevented by addition of exogenous calcium
Authors: Kawano Cristina Y. , Said Suraia
Published: May 2005

Hyphal tip growth is a highly polarized process of cell extension, which may be affected by chemical and physical stress. Neurospora crassa exposed to cold‐shock lost its polarized growth and dichotomous branches were detected. These effects were not observed in the presence of 500 mM Ca2+. We compared here the morphological pattern of a snow‐flake mutant (sn) and the wild‐type (wt) exposed to 4 °C. Hyphal morphology, nuclei, actin and microtubule distribution were analyzed. No effects on sn hyphal morphology were detected at 4 °C. Exogenous Ca2+ converted sn to an essentially wt appearance. The results presented here suggest that sn mutation and cold‐shock treatment have affected Ca2+ influx since addition of this cation to sn (30 °C) and to wt (4 °C) maintained polarized growth and normal nuclear and microtubules distribution. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of the concentration scaling law of the scattering coefficient of water solutions of Intralipid at 832 nm by comparison between collimated detection measurements and Monte Carlo simulations
Authors: Autiero Maddalena , Liuzzi Raffaele , Riccio Patrizia , Roberti Giuseppe
Published: May 2005

Background and Objectives

Intralipid (IP) is a scatterer extensively used in the building of phantoms for Biomedical Optics measurements. Recently, deviations from the linearity have been shown for the concentration scaling law of the scattering coefficient of IP water solutions at visible wavelengths. In this work this scaling law was determined at 832 nm.

Study Design/Materials and Methods

Space resolved transmittance measurements of a laser beam at 832 nm through water solutions of IP and ink were performed and compared with the corresponding results of Monte Carlo simulations.

Results

The comparison provides a quadratic dependence of μ on the volume‐to‐volume scatterer concentration, CIP, in the range of CIP values (0.0024<CIP<0.0075). These deviations from the linear behavior are related to the failure of the independent scatterer approximation.

Conclusion

The quadratic dependence of on CIP is in agreement with recent results obtained by other groups with different experimental techniques and is validated by a recent theoretical work. © 2005 Wiley‐Liss, Inc.
Cover Picture: Macromol. Chem. Phys. 10/2005
Authors: Girardeau Tom E. , Leisen Johannes , Beckham Haskell W.
Published: May 2005

Cover: The rotational dynamics of perdeuterated poly(oxyethylene) (POE) confined within nanotubes of stacked cyclodextrins were investigated using 2H solid‐state NMR spectroscopy. The experimental 2H NMR lineshapes are shown for some temperatures from 150 to 400 K. These lineshapes were successfully modeled as a three‐site discrete jump motion of a C2H bond on a cone with an opening angle of 70.5°. Such C2H bond reorientations result from exchange between trans, gauche+, and gauche− conformations, which can occur in nanotubes as gauche defects travel along the mostly trans POE chains. Further details can be found in the Full Paper by T. E. Girardeau, J. Leisen and H. W. Beckham* on page 998.
Infusion of SiC Nanoparticles Into SC‐15 Epoxy: An Investigation of Thermal and Mechanical Response
Authors: Rodgers Reneé M. , Mahfuz Hassan , Rangari Vijaya K. , Chisholm Nathaniel , Jeelani Shaik
Published: May 2005

Summary: In the present investigation we have developed a novel technique to synthesize nanocomposite materials consisting of SC‐15 epoxy resin and silicon carbide (β‐SiC) nanoparticles. A high intensity ultrasonic liquid processor was used to obtain a homogeneous molecular mixture of epoxy resin and β‐SiC nanoparticles. In this study, we have prepared three different samples containing 0.5, 1, and 1.5% of β‐SiC nanoparticles by weight of the epoxy resin. In parallel, control samples were also made following identical procedures without the infusion of nanoparticles. Test samples were characterized by TGA, DSC and three‐point bend flexural tests to evaluate thermal and mechanical properties. The results indicate that 1 wt.‐% loading derives the maximum improvement in both thermal and mechanical properties when compared to the neat system. The dispersion of nanoparticles and morphological changes were studied by field emission scanning electron microscopy (FE‐SEM) and high resolution transmission electron microscopy (TEM). These results demonstrate that the nanoparticles are spherical in shape (≈30 nm sizes) and are uniformly dispersed over the entire volume of the resin.

FE‐SEM micrograph of the plasma etched 1 wt.‐% SiC‐epoxy system.

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FE‐SEM micrograph of the plasma etched 1 wt.‐% SiC‐epoxy system.
Extrusion Monitoring of Polymer Melts Using a High‐Temperature Surface‐NMR Probe
Authors: Gottwald Antje , Scheler Ulrich
Published: May 2005

Summary: Extrusion is one of the major ways of polymer processing, and extrusion monitoring is important to control or improve the extrusion process and the product quality. Especially methods for in‐line monitoring are desired because those enable the fastest possible response and a localization of chemical reactions in reactive processing. Methods of optical and acoustic spectroscopy have successfully been implemented so far. NMR provides a wealth of information. Surface NMR mostly gives access to molecular mobility via relaxation times. These can be correlated to temperature, composition and homogeneity which are substantial indicators for the product quality. NMR is a non‐destructive method, which does not require direct contact with the sample and it is not restricted to optical transparent materials and is therefore suitable for extrusion monitoring. The problem for the adaptation is the hostile environment in and in front of an extruder for polymer melts. Here, a NMR surface probe is presented sustaining this environment in front of an extruder. First measurements with this device are shown.

High‐temperature surface‐NMR probe.

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High‐temperature surface‐NMR probe.
Preparation of Pyrolytic Carbon Black from Scrap Tire Rubber Crumb and Evaluation in New Rubber Compounds
Authors: Cataldo Franco
Published: May 2005

Summary: Pyrolytic carbon black (CBp) has been prepared by rubber crumb pyrolysis under nitrogen flow at 700 °C. The CBp obtained by this process had an average surface area of 81 m2 · g−1 and was obtained in 43% yield over the starting rubber crumb. Although the CBp surface area can be increased up to 109 m2 · g−1 by washing away the Zn‐ and Si‐based ashes with HF treatment, the CBp was tested in a standard NR/SBR‐based formulation without any purification and ash extraction. CBp was tested at increasing loading levels as partial or full replacement of a standard N339 furnace carbon black. CBp depresses the physical properties of the rubber compound in a way which is directly proportional to the amount added. The reason of this result and the limited reinforcing effect is discussed in terms of low surface area and low structure in comparison to N339 carbon black as well as in terms of low surface activity, the interference of the ashes and the poor dispersion. Ideas of further development works are outlined.

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External Stimuli‐Responsive Characteristics of Ionic Poly[(N,N‐diethylaminoethyl methacrylate)‐co‐(N‐vinyl‐2‐pyrrolidone)] Hydrogels
Authors: Çaykara Tuncer , Ayçiçek İbrahim
Published: May 2005

Summary: Polyelectrolyte hydrogels containing diprotic acid moieties sensitive to ionic strength changes of the swelling medium were synthesized from N,N‐diethylaminoethyl methacrylate (DEAEMA), N‐vinyl‐2‐pyrrolidone (VP) and itaconic acid (IA) by using ammonium persulfate (APS) as a free radical initiator in the presence of the cross‐linker, methylenebisacrylamide (MBAAm). The swelling behavior of the ionic poly[(N,N‐diethylaminoethyl methacrylate)‐co‐(N‐vinyl‐2‐pyrrolidone)] [P(DEAEMA/VP)] hydrogels were investigated in pure water; in NaCI solutions with pH 4 and 9; and in water‐acetone mixtures depending on the IA content in the hydrogel. The average molecular mass between cross‐links ($\overline M _{\rm c}$) and polymer‐solvent interaction parameter (χ) of the hydrogels were determined from equilibrium swelling values. The pulsatile swelling behavior was also observed in response to solvent changes between the solution in water and in acetone. The equilibrium swelling ratio of these hydrogels was basically unaffected with change in temperature. The swelling variations were explained according to the swelling theory based on the hydrogel chemical structure.

Pulsatile swelling behavior of ionic P(DEAEMA/VP) hydrogels in response to solvent changes between water and acetone at 25 °C.

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Pulsatile swelling behavior of ionic P(DEAEMA/VP) hydrogels in response to solvent changes between water and acetone at 25 °C.
The Influence of Cooling Rate on the Specific Volume of Isotactic Poly(propylene) at Elevated Pressures
Authors: Van der Beek Maurice H. E. , Peters Gerrit W. M. , Meijer Han E. H.
Published: May 2005

Summary: We used a custom designed dilatometer to measure quantitatively the time evolution of the specific volume of (semi‐crystalline) polymers for an unusual combined wide range of cooling rates and elevated pressures, covering processing conditions. For an isotactic poly(propylene), applying the Schneider rate equations for quiescent crystallization, experimental results are compared to numerical predictions. Average cooling rates imposed during crystallization of the material vary from 0.1 to 35 °C · s−1 while pressures range from 20 to 60 MPa. The results show the well‐known profound influence of pressure and cooling rate on the specific volume. An increasing cooling rate shifts the crystallization temperature Tc towards lower temperatures, increases the final specific volume, and the transition due to crystallization is more gradual and widespread. For the highest cooling rate applied, the shift in Tc is as much as 30 °C, while the final specific volume increases up to 1.4%. Increasing pressure has an opposite effect on the shift in Tc, while the final specific volume, after pressure release, also increases. Finally, a comparison of numerical predictions with experimental data shows that the crystallization temperature Tc is consistently predicted too low, and that the predictions at high cooling rate are sensitive to (small) variations in model parameters.

Influence of cooling rate on the specific volume of iPP.

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Influence of cooling rate on the specific volume of iPP.
Artificial Neural Networks Associated to Calorimetric Measurements Used as a Method to Predict Polymer Composition of High Solid Content Emulsion Copolymerizations
Authors: Giordani Domingos Sávio , Lona Liliane M. F. , McKenna Timothy F. , Krähenbühl Maria A. , dos Santos Amilton Martins
Published: May 2005

Summary: Inspired by biological systems, artificial neural networks (ANN) have demonstrated to be powerful tools to model non‐linear systems, such as high solid content latexes produced by emulsion polymerization which have a great importance in the polymeric industry, essentially for environmental reasons, since they usually have water as a continuous phase. The quality of the produced polymer is closely related to the structure of the polymeric chain. In order to propose technical and economically feasible alternatives to control a polymeric structure, this work is aimed to develop a new methodology based on ANN associated with calorimetry to predict the polymeric structure. The designed ANN presented excellent results when tested with process condition variations (such as temperature and reaction time) as well as when they were submitted to test concerning the variation on the proportion of monomers in the latex formulation. Hence, it was possible to conclude that ANN, associated to calorimetry, lead to an efficient method to predict the polymer composition in emulsion copolymerizations.

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A dual‐port dual‐frequency coaxial dual‐helical antenna with high decoupling
Authors: Zürcher J.‐F.
Published: May 2005

In order to obtain a circularly polarized and compact directive antenna for harmonic direction finding (HDF) of small animals using radio‐frequency identification (RFID), a dual‐port, dual‐frequency coaxial dual‐helical antenna is developed. The two frequencies are harmonics (2.45 and 4.9 GHz in our case). The antenna is realized using two coaxial, contradirective helices. Two different principles of realization are tested. The measured decoupling between ports is between 22 and 28 dB for the best antenna. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 1–4, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20883
A novel compact and wideband shorted patch antenna
Authors: Lee Chi‐Hun , Choi Dong‐Hyuk , Park Seong‐Ook
Published: May 2005

A novel compact shorted patch antenna with the bowtie‐type patch and the dual triangle portion to obtain a large bandwidth (790–970 MHz) is presented in this paper. Using shorted patches with via holes, a size reduction of 95.7% is achieved, as compared to that of the conventional half‐wave patch antenna. Moreover, it has 10‐dB return‐loss bandwidth of 20.4% for the GSM and CDMA bands. This proposed antenna exhibits not only a compact and a thin profile, but also wideband characteristics. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 4–6, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20884
A new approach for the linearization of a distributed amplifier
Authors: Paul D. K. , Parkinson G.
Published: May 2005

This paper describes the application of the feedforward linearization technique to a distributed amplifier. The circuit architecture of the distributed amplifier is used in a new way to simplify the feedforward system's configuration. A distributed amplifier using a pseudomorphic HEMT with feedforward linearization based on the new concept is simulated to evaluate the performance and demonstrate the feasibility of achieving broadband linearity. The experimental results for an MIC implementation are also presented as proof of the concept. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 15–17, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20887
A novel low‐pass filter using defected ground structures
Authors: Guan Xue‐Hui , Li Guo‐Hui , Ma Zhewang
Published: May 2005

In this paper, an equivalent‐circuit model of a defected ground structure (DGS) is applied to explain the characteristics of the DGS. The parameters of the circuit model are extracted from the EM‐simulation results. A novel three‐pole lowpass filter is proposed and optimized by using the defected ground structures. It is demonstrated that the filter can provide a sharp rate of attenuation in the stop‐band, as predicted. To further verify this method, the filter with DGS is fabricated on a 30 × 30 mm2 substrate. A comparison between the simulation and the measurement confirms the effectiveness of the proposed schemes. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 17–20, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20888
Assessment of an alternative six‐port circuit for broadband complex voltage‐ratio measurements
Authors: Casares‐Miranda F. P. , Otero Pablo , Márquez‐Segura E. , Camacho‐Peñalosa C.
Published: May 2005

The assessment of an alternative six‐port circuit in terms of frequency behavior when used to measure complex voltage ratio is presented. A numerical comparison to commonly used and well‐known six‐port circuits is carried out. The presented results can help us to choose between different six‐port configurations depending on the application, and show that the proposed circuit is the most suitable in general. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 24–27, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20890
An RHCP/LHCP switchable slotline‐fed slot‐ring antenna
Authors: Ho Min‐Hua , Wu Ming‐Ting , Hsu Chung‐I G. , Sze Jia‐Yi
Published: May 2005

In this paper, two irises are orthogonally connected to a slot‐ring antenna via short‐length slits with each of the slits loaded by a pin diode. This antenna can be switched back and forth between right‐hand and left‐hand circular polarization by turning on/off the pin diodes. The slot ring is excited by a slotline. The conformability of the slotline with an SMA is accomplished by inserting a CPW‐to‐slotline transition between them. An experimental antenna is built on a low‐cost FR4 substrate in order to validate the design. The antenna's uniplanar architecture and its polarization‐diversity property will be very useful in wireless‐communication systems. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 30–33, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20892
Compact coplanar waveguide band‐pass filter at the S‐band
Authors: Bonache J. , Martín F. , Falcone F. , García‐García J. , Gil I. , Lopetegi T. , Laso M. A. G. , Marqués R. , Medina F. , Sorolla M.
Published: May 2005

In this paper, it is demonstrated that split‐ring resonators (SRRs) magnetically coupled to a coplanar waveguide (CPW) structure can be applied to the design of miniaturized band‐pass filters. To this end, a two‐stage prototype device consisting of a CPW with two signal‐to‐ground shorts and a series gap, combined with SRRs, is designed and fabricated. By virtue of the subwavelength operation of SRRs at their quasi‐static resonance, the filter dimensions can be made to be very small in comparison to conventional distributed implementations. Other relevant features of the proposed structures are: (i) low insertion losses (<3.5 dB) in the allowed band, (ii) out‐of‐band rejection levels above 30 dB, and (iii) very sharp transition slopes. It is believed that these SRR‐based structures can be of interest for the design of planar filters with potential application in future communication transceivers. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 33–35, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20893
Wideband 2D array of microstrip fed rectangular‐slot antennas for radar applications
Authors: Eldek Abdelnasser A. , Elsherbeni Atef Z. , Smith Charles E.
Published: May 2005

This paper presents the design of a wideband 16 × 4 element array of a microstrip‐proximity‐fed rectangular‐slot antenna for marine radar systems operating in the X‐band. A wideband corporate‐feed network is designed to feed the proposed array. The new design has a small size, a wide bandwidth of 52%, and good radiation characteristics in the entire operating band. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 36–40, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20894
Optically tunable multiturn spiral inductor for RF applications
Authors: Bheema Rao N. , Chandorkar A. N.
Published: May 2005

The tunability of an inductor using an additional conductor segments with optical switching is presented. When the additional conductor is in the horizontal plane of the spiral inductor, a two‐turn spiral‐inductor tunability of 30% can be obtained. The tunability is reduced when the number of turns of the spiral is increased. The tunability can be further improved over the horizontal position by choosing an additional conductor segment structure above the spiral inductor (that is, in the vertical plane). The tunability of the inductor can be improved by 54% as compared to the horizontal tuning for a high number of turns of the spiral inductor (N = 6). This analysis was carried out using the TSMC 0.18‐μm 1P6M process. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 40–43, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20895
Microstrip bandpass filter using series‐connected triangular patches
Authors: Chen Jian‐Xin , Xue Quan
Published: May 2005

A novel microstrip bandpass filter using series‐connected triangular patches is proposed. Centered at 1.34 GHz, the insertion loss of the second resonant mode is about 18‐dB below that of the first mode. A demonstration filter is designed, fabricated, and tested. The theoretical and experimental results are presented. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 46–48, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20897
Frequency‐dependent guided‐wave characteristics of periodically series‐capacitive loaded coplanar waveguides
Authors: Zhu Lei , Shi Huamin
Published: May 2005

Periodically series‐capacitive loaded transmission line on coplanar waveguide (CPW) is studied in this work as a planar 1D guided‐wave medium. The two effective per‐unit‐length transmission parameters, that is, propagation constant and characteristic impedance, are numerically extracted to demonstrate the guided‐wave characteristics in a frequency range covering the first stopband, first passband, and second stopband. To further provide a proof, the six‐cell periodic CPW with impedance transformers at two sides are designed and fabricated. The predicted S‐parameters are well confirmed by the measured ones. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 54–58, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20899
T‐shaped monopole antenna with shorted L‐shaped strip‐sleeves for WLAN 2.4/5.8‐GHz operation
Authors: Wu Jeun‐Wen , Wang Yau‐Der , Hsiao Hai‐Ming , Lu Jui‐Han
Published: May 2005

A novel dual‐broadband T‐shaped monopole antenna with dual shorted L‐shaped strip‐sleeves for 2.4/5.8‐GHz wireless local area networks (WLANs) is proposed. Dual L‐shaped strip‐sleeves to be shorted with the ground plane are introduced in order to excite the upper resonant mode for operation at the 5.8‐GHz band. The obtained impedance bandwidths reach about 35% for the 2.4‐GHz band and 10.0% for the 5.8‐GHz band, which meets the required bandwidth specifications of the IEEE 802.11a/b/g standards. The measured peak antenna gains for the operating frequencies across dual WLAN bands are measured to be 3.4 and 1.0 dBi, respectively, with gain variations within 0.8 dBi. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 65–69, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20903
A miniaturized high‐Q duplexer with attenuation poles using novel microstrip stacked open‐loop resonators
Authors: Jang Suk‐Hyung , Lee Jong‐Chul
Published: May 2005

In this paper, novel microstrip open‐loop resonator (OLR) bandpass filters are presented. By introducing additional spiral inductors as well as gap‐coupled capacitors, the bandpass filters (BPFs) exhibit another attenuation pole at the upper stopband. Also, a novel miniaturized high‐Q duplexer for Universal Mobile Telecommunications System (UMTS) bands using these BPFs is discussed. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 69–72, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20904
A new free‐space method for measurement of electromagnetic parameters of biaxial materials at microwave frequencies
Authors: Yin Hong‐Cheng , Chao Zeng‐Ming , Xu Yan‐Ping
Published: May 2005

A free‐space method for the measurement of biaxial material is proposed in this paper. Four complex transverse constitutive parameters are directly computed from the reflection and transmission coefficients of a planar sample in free space for the normally incident plane wave with two polarizations. However, because of the extreme insensibility of the reflection and transmission coefficients versus the longitudinal constitutive parameters for thin planar biaxial materials, the correct reconstruction of longitudinal parameters cannot be accomplished by the free‐space method. Considering that the principal coordinate system (PCS) to characterize biaxial material possibly does not coincide with the measurement coordinate system (MCS), an approach to determine PCS is also presented to ensure practicability of this method. A measurement system has been set up to perform measurements of transverse parameters of biaxial material and the validity of this method is experimentally verified. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 72–78, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20905
Complementary split‐ring resonator for compact waveguide filter design
Authors: Ortiz N. , Baena J. D. , Beruete M. , Falcone F. , Laso M. A. G. , Lopetegi T. , Marqués R. , Martín F. , García‐García J. , Sorolla M.
Published: May 2005

In this paper, the potential use of complementary split‐ring resonators (CSRRs) to design very compact waveguide filters, by etching a CSRR in the center of a metallic sheet, is demonstrated. This original layout reduces the dimensions of the well‐known resonant‐cavity waveguide filters coupled by irises. This has been made feasible due to the self‐resonance property of the CSRR. Thus, it is possible to design waveguide filters with lengths equal to the thickness of a metallic sheet. Consequently, this technique paves the way for the design of miniaturized waveguide filters, in contrast to conventional waveguide filters, based on bulk resonators. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 88–92, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20909
Muscle cramps
Authors: Miller Timothy M. , Layzer Robert B.
Published: May 2005

Muscle cramps are a common problem characterized by a sudden, painful, involuntary contraction of muscle. These true cramps, which originate from peripheral nerves, may be distinguished from other muscle pain or spasm. Medical history, physical examination, and a limited laboratory screen help to determine the various causes of muscle cramps. Despite the “benign” nature of cramps, many patients find the symptom very uncomfortable. Treatment options are guided both by experience and by a limited number of therapeutic trials. Quinine sulfate is an effective medication, but the side‐effect profile is worrisome, and other membrane‐stabilizing drugs are probably just as effective. Patients will benefit from further studies to better define the pathophysiology of muscle cramps and to find more effective medications with fewer side‐effects. Muscle Nerve, 2005
Synthesis of poly(1‐hexene)s end‐functionalized with phenols
Authors: Yanjarappa Mallinamadugu J , Sivaram Swaminathan
Published: May 2005

Electrophilic alkylations of phenol/2,6‐dimethylphenol were performed with vinylidene‐terminated poly(1‐hexene)s using BF3·OEt2 catalyst. Vinylidene‐terminated poly(1‐hexene)s with Mn varying from 400 to 10000 were prepared by bulk polymerization of 1‐hexene at 50 to −20 °C using Cp2ZrCl2/MAO catalysts. The phenol/2,6‐dimethylphenol‐terminated poly(1‐hexene)s was characterized by NMR (1H, 13C), UV, IR and vapor phase osmometer (VPO). The isomer distribution (ortho, para and ortho/para) was determined by 13P NMR using a phosphitylating reagent, namely 2‐chloro‐1,3,2‐dioxaphospholane. The number‐average degree of functionality (Fn) >0.9 with >95% para selectivity could be achieved using low‐molecular‐weight oligomers of poly(1‐hexene)s. Copyright © 2005 Society of Chemical Industry
Photochemistry and photocuring properties of thiol‐substituted α‐aminoalkylphenone as radical photoinitiator
Authors: Kura Hisatoshi , Oka Hidetaka , Ohwa Masaki , Matsumura Tadayoshi , Kimura Akira , Iwasaki Yohei , Ohno Teruhisa , Matsumura Michio , Murai Hisao
Published: May 2005

Thiol‐substituted α‐aminoalkylphenone was newly developed as a radical photoinitiator. Introduction of the thiol group drastically improved photosensitivity in an alkaline developable resist formulation composed of a prepolymer and a multifunctional acrylate monomer. The improvement in the photocuring speed was explained by a mechanism based on chain transfer reaction of the thiol group. Time‐resolved electron spin resonance (ESR) spectroscopy indicated that the thiol group attached to the chromophore does not influence the photochemical process to generate primary radicals. The photoinitiation of α‐aminoalkylphenone can be spectrally sensitized by 2,4‐diethylthioxanthone (DETX). However, thiol‐substituted α‐aminoalkylphenone showed smaller spectral sensitization than the corresponding compound without a thiol group. Time resolved laser flash photolysis indicated that the rate constant of the quenching of the triplet state of DETX by thiol‐substituted α‐aminoalkylphenone is twice as large as that by the corresponding one without a thiol group. This suggests that, besides energy transfer from DETX in the excited triplet state to the α‐aminoalkylphenone, the thiol group quenches the excited triplet state of DETX via charge transfer and/or hydrogen transfer, as supported by the ESR analysis using a spin trapping technique, and lowers the efficiency of the spectral sensitization effect. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1684–1695, 2005
Theoretical study of the structures and properties of cyclic nitramines: Tetranitrotetraazadecalin (TNAD) and its isomers
Authors: Qiu Ling , Xiao He Ming , Ju Xue Hai , Gong Xue Dong
Published: May 2005

Density Functional Theory (DFT) was employed to study the geometries, electronic structures, infrared vibrational spectra, and thermodynamic properties of seven isomeric cyclic nitramines of C6H10N8O8 (i.e., TNAD and its six isomers) at the B3LYP/6‐31G* level of theory. The experimental results available for TNAD were used to determine the reliability of the DFT method for generating structural and IR spectroscopic values for these molecular systems. The relative stabilities of the conformers were evaluated from the energy differences of the structures. Detonation properties of various conformers were evaluated using the Kamlet‐Jacobs equations, and it was found that all the calculated results are comparable to the available experimental data. In addition, the calculated results demonstrate that all title compounds can be used as excellent propellant ingredients. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Geometry optimization of the cytosine molecules in a cytosine stack using the B3LYP crystal orbital method
Authors: Szekeres Zs. , Bogár F. , Bartha F. , Ladik J.
Published: May 2005

The B3LYP DFT crystal orbital method was applied (with helical periodicity) to calculate the total energy per unit cell of a cytosine (C) molecule in a C stack. Applying afterwards the multidimensional metric method in its BFGS form, the geometry of a C molecule was optimized in the stack of DNA B (3.36 Å stacking distance, 36° rotation). For comparison, we optimized also the geometry of a C trimer and pentamer (in DNA B form) using the Gaussian 03 program for the B3LYP molecular calculation and the default method for the geometry optimization. The results of the two completely different calculations agree quite well, which supports our confidence in the results of our C stack calculation. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Relationship between a high density of sika deer and productivity of the short‐grass (Zoysia japonica) community: a case study on Kinkazan Island, northern Japan
Authors: Ito Takehiko Y. , Takatsuki Seiki
Published: May 2005

An extremely high‐density (ca. 800 deer km−2) wild sika deer population uses a short‐grass community dominated by Zoysia japonica on Kinkazan Island in northeastern Japan. To explain why the density of wild deer is quite high on the Zoysia community, (1) we quantified the seasonal productivity of the Zoysia community, (2) we compared food availabilities among the plant communities, and (3) we described the habitat selection by the deer in different seasons. Food availability was greater on the Zoysia community than in the forest understory from spring to fall. The productivity of the Zoysia community was high enough to support the actual high density of the deer (814 deer km−2) in summer. However, the productivity markedly decreased in winter, when the deer density decreased to less than half (358 deer km−2) of the summer value. In contrast, the deer density of the adjacent forests was highest in winter (154 deer km−2) and lowest in spring (19 deer km−2). These results suggest that the deer using the Zoysia community in summer left and were “absorbed” into the adjacent forest in winter. If such an adjacent community were absent, many deer would not survive, and consequently the deer density on the Zoysia community in summer would not be so high. This intercommunity movement is particularly important for the deer using a plant community like the Zoysia community, which is highly productive but has a small standing biomass.
Changes in morphological traits of the cabbage aphid (Brevicoryne brassicae) associated with the use of different host plants
Authors: Ruiz‐Montoya Lorena , Nùñez‐Farfán Juan , Domínguez César A.
Published: May 2005

The genetic and morphological differentiation of insect populations in relation to the use of different host plants is an important phenomenon that predates ecological specialisation and speciation in sympatric conditions. In this study, we describe the morphological variation of populations of Brevicoryne brassicae (Homoptera: Aphididae) associated with two host species, Brassica oleracea and Brassica campestris, which occur sympatrically in the highlands of Chiapas, Mexico. The study is aimed at obtaining evidence regarding phenotypic differentiation induced by, or associated with, the use of distinct but closely related host species. Seven morphological characters were measured in 696 wingless aphids collected from plants of the two host species at four localities. Morphological variation was summarised through principal components analysis (PCA). Sixty‐two percent of morphological variation was explained by the first two PCs. The first component (PC1) was related to the general size of appendages, and PC2 was interpreted as the relationship between body size (body and leg size) and antenna length. Aphids growing on B. campestris were bigger than those collected from B. oleraceae. Significant differences between hosts were detected for PC1, whereas a significant effect of locality, host, and the interaction locality × host was detected for PC2. These results indicate that the average phenotype of B. brassicae individuals inhabiting different host‐plant species differs as a consequence of the contrasting feeding environments the host species provide.
Good and Bad Experiences of Family Presence During Acute Care and Resuscitation. What Makes the Difference?
Authors: Axelsson Åsa B. , Zettergren Margaretha , Axelsson Christer
Published: May 2005

Background: Family presence (FP) in the resuscitation room is still controversial, and its appropriateness for patient and family has been discussed. We examined both positive and negative experiences in order to establish the reasons for the difference.

Aim: The aim of the present literature review was to describe patients', relatives' and staff's opinions and experiences of FP during invasive procedures and resuscitation.

Method: 12 original papers, published between January 1995 and February 2003, were reviewed.

Results: Most patients and relatives agreed that they had positive experiences of FP. They described how FP enhanced the feeling of support and connectedness within the family. Family members believed that FP helped them in their grieving process. Most staff members without FP experience felt that FP would increase the risk of psychological distress for the family. Those who had participated in an FP programme believed that FP was not only beneficial for the family but also for staff.

Conclusion: Family presence during resuscitation and acute care has the potential to enhance the care of the patient and to benefit everyone involved. However, implementation of FP during resuscitation must take account of potential problems.