bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Some Novel Thioxanthenone‐Fused Azacrown Ethers, and Their Use as New Catalysts in the Efficient, Mild, and Regioselective Conversion of Epoxides to β‐Hydroxy Thiocyanates with Ammonium Thiocyanate
Authors: Sharghi Hashem , Beni Alireza Salimi , Khalifeh Reza
Published: July 2007

The regioselective ring‐opening reactions of some epoxides with ammonium thiocyanate in the presence of a series of new 9H‐thioxanthen‐9‐one‐fused azacrown ethers, i.e., 7–11 (Scheme 1), and also of dibenzo[18]crown‐6 (12), Kryptofix® 22 (13), and benzo[15]crown‐5 (14) were studied (Tables 1 and 2). The epoxides were subjected to cleavage by NH4SCN in the presence of these catalysts under mild conditions in various aprotic solvents. Reagents and conditions were identified for the synthesis of individual β‐hydroxy thiocyanates in high yield and with more than 90% regioselectivity. The results can be discussed in terms of a four‐step mechanism (Scheme 2): 1) formation of a complex between catalyst and NH4SCN, 2) release of SCN− from the complex, 3) reaction of the released SCN− at the sterically less hindered site of the epoxide, and 4) regeneration of the catalyst. The major advantages of this method are the high regioselectivity, the simple regeneration of the catalyst, the reuse of it through several cycles without a decrease of activity, and the ease of workup of the reaction mixtures.
The growth inhibitory effect of actein on human breast cancer cells is associated with activation of stress response pathways
Authors: Einbond Linda Saxe , Su Tao , Wu Hsan‐au , Friedman Richard , Wang Xiaomei , Ramirez Alejandro , Kronenberg Fredi , Weinstein I. Bernard
Published: July 2007

Previous studies indicate that the triterpene glycoside actein from the herb black cohosh inhibits growth of human breast cancer cells. This study seeks to identify genes altered in human breast cancer cells by treatment with actein, using gene expression analysis. We treated MDA‐MB‐453 human breast cancer cells with actein at 2 doses, 20 or 40 μg/mL, for 6 or 24 hr. We identified 5 genes that were activated after each of the treatments that are known to play a role in cellular responses to diverse stresses, including the DNA damage and unfolded protein responses. In addition, four genes that mediate the integrated stress response (ISR), including activating transcription factor 4, were induced under at least one of the 4 treatment conditions. We used hierarchical clustering to define clusters comprising patterns of gene expression. Two ISR genes, activating transcription factor 3 (ATF3) and DNA damage‐ inducible transcript 3, and lipid biosynthetic genes were activated after exposure to actein at 40 μg/mL for 6 hr, whereas the cell cycle genes cyclin E2 and cell division cycle 25A were repressed. Our results suggest that actein induces 2 phases of the ISR, the survival phase and the apoptotic phase, depending on the dose and duration of treatment. We confirmed the results of gene expression analysis with real‐time RT‐PCR for 18 selected genes and Western blot analysis for ATF3. Since actein activated transcription factors that enhance apoptosis, and repressed cell cycle genes, it may be useful in the prevention and therapy of breast cancer. © 2007 Wiley‐Liss, Inc.
Induction of potent CD4+ T cell‐mediated antitumor responses by a helper HER‐2/neu peptide linked to the Ii‐Key moiety of the invariant chain
Authors: Voutsas Ioannis F. , Gritzapis Angelos D. , Mahaira Louisa G. , Salagianni Maria , Hofe Eric von , Kallinteris Nikoletta L. , Baxevanis Constantin N.
Published: July 2007

The Ii‐Key fragment from the MHC class II‐associated invariant chain (or Ii protein) has been shown to facilitate direct charging of MHC class II epitopes to the peptide binding groove. The purpose of the present study was to test the potential of a series of Ii‐Key/HER‐2/neu(776–790) hybrid peptides to generate increased frequencies of peptide‐specific CD4+ T cells over the native peptide in mice transgenic (Tg) for a chimeric human mouse class II molecule (DR4‐IE) (H‐2b) as well as their antitumor potency. Following in vivo priming, such hybrid peptides induced increased proliferation and frequencies of IFN‐γ producing CD4+ T cells in response to either syngeneic dendritic cells pulsed with native peptide, or HLA‐DR4+ human tumor cell lines expressing HER‐2/neu. Hybrid peptides were more stable in an off‐rate kinetics assay compared to the native peptide. In addition, antigen‐specific CD4+ T cells from hybrid peptide immunized DR4‐IE Tg mice synergized with HER‐2/neu(435–443)‐specific CD8+ T cells from HLA‐A2.1 Tg HHD (H‐2b) mice in producing antitumor immunity into SCID mice xenografted with the HER‐2/neu+, HLA‐A2.1+ and HLA‐DR4+ FM3 human melanoma cell line. High proportions of these adoptively transferred HER‐2/neu peptide‐specific CD4+ and CD8+ T cells infiltrated FM3‐induced tumors (tumor infiltrating lymphocytes; TIL) in SCID mice. CD8+ TIL exhibited long‐lasting antitumor activity when cotransferred with CD4+ TIL, inducing regression of FM3 tumors in a group of untreated, tumor‐bearing SCID mice, following adoptive transfer. Our data show that Ii‐Key modified HER‐2/neu(776–790) hybrid peptides are sufficiently potent to provide antigen‐specific CD4+ TH cells with therapeutic antitumor activity. © 2007 Wiley‐Liss, Inc.
Improvement of bonding strength between biomimetic apatite coating and substrate
Authors: Qu Haibo , Wei Mei
Published: July 2007

Bone‐like apatite coatings were prepared using a biomimetic method in a modified simulated body fluid (m‐SBF). The effect of the m‐SBF volume on the apatite coating quality was studied. Three m‐SBF volumes, 50, 100, and 200 mL, were employed to immerse titanium substrates in a sealed container so as to produce apatite coatings with different properties, namely types I, type II, and type III apatite coatings, respectively. The coatings were characterized using X‐ray diffraction and environmental scanning electron microscope. The bonding between the coating and the Ti substrate was evaluated using an adhesive strength test. All three apatite coatings demonstrated a poorly crystallized structure, and the coatings formed exhibited a uniformed surface morphology. Further increasing the m‐SBF volume, small globules of apatite started to form on the surface of the coating. The bonding strength for the three coating systems were 8.52 ± 2.41, 10.36 ± 2.78, and 17.23 ± 2.55 MPa for types I, II, and III apatite coatings, respectively. The failure analyses suggested that type III coating failed mostly at the interface between the coating and the substrate, while type I and II coatings failed mostly within the apatite coating. Our study revealed that a dense, thick, well‐adhered apatite coating could be achieved by carefully controlling the volume of m‐SBF. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Injectable calcium phosphate cement: Effects of powder‐to‐liquid ratio and needle size
Authors: Burguera Elena F. , Xu Hockin H. K. , Sun Limin
Published: July 2007

Calcium phosphate cement (CPC) sets in situ and forms apatite with excellent osteoconductivity and bone‐replacement capability. The objectives of this study were to formulate an injectable tetracalcium phosphate‐dicalcium phosphate cement (CPCD), and investigate the powder/liquid ratio and needle‐size effects. The injection force (mean ± SD; n = 4) to extrude the paste increased from (8 ± 2) N using a 10‐gauge needle to (144 ± 17) N using a 21‐gauge needle (p < 0.05). With the 10‐gauge needle, the mass percentage of extruded paste was (95 ± 4)% at a powder/liquid ratio of 3; it decreased to (70 ± 12)% at powder/liquid = 3.5 (p < 0.05). A relationship was established between injection force, F, and needle lumen cross‐sectional area, A: F = 5.0 + 38.7/A0.8. Flexural strength, S, (mean ± SD; n = 5) increased from (5.3 ± 0.8) MPa at powder/liquid= 2 to (11.0 ± 0.8) MPa at powder/liquid = 3.5 (p < 0.05). Pore volume fraction, P, ranged from 62.4% to 47.9%. A relationship was established: S = 47.7 × (1 – P)2.3. The strength of the injectable CPCD matched/exceeded the reported strengths of sintered porous hydroxyapatite implants that required machining. The novel injectable CPCD with a relatively high strength may be useful in filling defects with limited accessibility such as periodontal repair and tooth root‐canal fillings, and in minimally‐invasive techniques such as percutaneous vertebroplasty to fill the lesions and to strengthen the osteoporotic bone. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Spectrofluorimetric determination of bile acid using a europium‐doxycycline probe
Authors: Wang Ting , Wang Xiaolei , Jiang Chongqiu
Published: July 2007

A new spectrofluorimetric method was developed for the determination of trace amounts of bile acid (BA). Using europium ion (Eu3+)‐doxycycline (DC) as a fluorescent probe, in a buffer solution of pH=7.0, BA can remarkably reduce the fluorescence intensity of the DC‐Eu3+ complex at λ=612 nm; the reduced fluorescence intensity of the Eu3+ is proportional to the concentration of BA. Optimum conditions for the determination of BA were also investigated. The linear range and detection limit for the determination of BA were 5.0 × 10−8 mol/L to 5.5 × 10−7 mol/L and 1.1 × 10−8 mol/L, respectively. This method is practical and relatively free of interference from coexisting substances, and can be successfully applied to assess BA in serum samples. J. Clin. Lab. Anal. 21:207–212, 2007. © 2007 Wiley‐Liss, Inc.
Novel method for clearing red blood cell debris from BacT/ALERT® blood culture medium for improved microscopic and antimycobacterial drug susceptibility test results
Authors: Gopinath Krishnamoorthy , Kumar Sandeep , Mani Sankar Manimuthu , Singh Sarman
Published: July 2007

Even though automation in mycobacterial culture has immensely improved the detection of organisms, identification of species and antimycobacterial susceptibility testing from blood culture bottles remain cumbersome and error‐prone due to the presence of intact red blood cells (RBCs). The removal or lysis of these RBCs and excessive protein from the blood components could theoretically help improve this process. The present study reports an effective method that uses ammonium chloride (NH4Cl) and Triton X‐100 to lyse the RBCs in blood culture medium. The method was optimized by preparing various concentrations of NH4Cl and Triton X‐100, and incubation conditions, leading to eight protocols. The lysis protocol with a concentration of 150 mM of NH4Cl, 0.5% Triton X‐100, and 1% potassium bicarbonate, pH 7.0, and incubation at 37°C for 15 min was found to be optimal. This method not only made the culture medium clear, the protein concentration decreased from 753.5±39.4 to 53.2±4.2 mg/mL in the M. tuberculosis‐spiked culture medium and in the blood culture medium inoculated with the blood from tuberculosis patients. The method had no adverse effect on mycobacteria, and no depletion of M. tuberculosis colony‐forming units was found. The lysate could be used for antimycobacterial susceptibility testing with no difficulty in setting the mycobacterial concentration of inoculum to 0.5 McFarland standards. Furthermore, this method had the added advantage in the microscopy and molecular methods for the speciation of Mycobacterium sp. J. Clin. Lab. Anal. 21:220–226, 2007. © 2007 Wiley‐Liss, Inc.
Insulin receptor substrate (IRS)‐1 regulates murine embryonic stem (mES) cells self‐renewal
Authors: Rubin Raphael , Arzumanyan Alla , Soliera Angela Rachele , Ross Brian , Peruzzi Francesca , Prisco Marco
Published: July 2007

Mouse embryonic stem (mES) cells are pluripotent cells that can be propagated in vitro with leukemia inhibitory factor (LIF) and serum. Intracellular signaling by LIF is principally mediated by activation of STAT‐3, although additional pathways for self‐renewal have been described. Here, we identified a novel role for Insulin receptor substrate‐1 (IRS‐1) as a critical factor in mES cells self‐renewal and differentiation. IRS‐1 is expressed and tyrosyl phosphorylated during mES cells self‐renewal. Differentiation of mES cells, by LIF withdrawal, is associated with a marked reduction in IRS‐1 expression. Targeting of IRS‐1 by si‐IRS‐1 results in a severe reduction of Oct‐4 protein expression and alkaline phosphatase activity, markers of undifferentiated mES cells. IRS‐1 targeting does not interfere with LIF‐induced STAT‐3 phosphorylation, but negatively affects protein kinase B (PKB/AKT) and glycogen synthase kinase‐3 (GSK‐3β) phosphorylation, which are downstream effectors of the LIF‐mediated PI3K signaling cascade. Targeting of IRS‐1 also results in a marked down regulation of Id‐1 and Id‐2 proteins expression, which are important components for self‐renewal of ES cells. Conversely, over expression of IRS‐1 inhibits mES cell differentiation. Taken together, these results suggest that expression and activity of IRS‐1 are critical to the maintenance of the self‐renewal program in mES cells. J. Cell. Physiol. 213: 445–453, 2007. © 2007 Wiley‐Liss, Inc.
A mechanism for stimulation of biosynthesis by electromagnetic fields: Charge transfer in DNA and base pair separation
Authors: Blank Martin , Goodman Reba
Published: July 2007

Electrons have been shown to move in DNA, and a specific DNA sequence is associated with the response to EM fields. In addition, there is evidence from biochemical reactions that EM fields can accelerate electron transfer. Interaction with electrons could displace electrons in H‐bonds that hold DNA together leading to chain separation and initiating transcription. The effect of charging due to electron displacement on the energetics of DNA aggregation shows that electron transfer would favor separation of base pairs, and that DNA geometry is optimized for disaggregation under such conditions. Electrons in the H‐bonds of both DNA and the surrounding water molecules fluctuate at frequencies that are much higher than the frequencies of the EM fields studied. The characteristics of the fluctuations suggest that the applied EM fields are effectively DC pulses and that interactions extend to microwave frequencies. J. Cell. Physiol. 214:20–26, 2008. © 2007 Wiley‐Liss, Inc.
Expression of CLMP, a novel tight junction protein, is mediated via the interaction of GATA with the kruppel family proteins, KLF4 and Sp1, in mouse TM4 sertoli cells
Authors: Sze Kit‐Ling , Lee Will M. , Lui Wing‐Yee
Published: July 2007

Regulation of tight junction protein expressions in Sertoli cells is important for germ cell translocation across the blood‐testis‐barrier (BTB) during spermatogenesis. In this study, a novel tight junction transmembrane protein, CLMP, found expressed in mouse testis was shown to localize at the BTB along with the tight junction marker ZO‐1. By the use of transient transfection assay performed in a mouse Sertoli cell–cell line, TM4 cells, we showed that the minimal CLMP promoter was located between nucleotides −550 and −288 relative to the translation start site. Site‐directed mutagenic studies showed that three motifs, namely GATA, KLF4, and SRY, within this region functionally co‐operated with one another to regulate CLMP gene transcription. Using specific antibodies in EMSA analysis, a ternary protein complex GATA‐1/GATA‐6/KLF4 was detected at all the three motifs, suggesting that a looping mechanism might involve in regulating CLMP gene transcription. Interestingly, the ubiquitously expressed transcription factors, Sp1 and Sp3, were also found in this ternary complex over the KLF4 motif. Overexpression of KLF4 significantly increased the promoter activity whilst overexpression of Sp1 or Sp3 exerted an opposite effect. In particular, co‐transfection studies showed that Sp1 could significantly abolish the KLF4‐induced transactivation of the CLMP gene, suggesting that KLF4 and Sp1 might compete for the same binding site on the CLMP promoter. Taken together, this differential interaction of the transcription factors, GATA‐1, GATA‐6, KLF4, Sp1, and Sp3, in CLMP gene expression might provide a precise machinery in regulating Sertoli cell tight junction dynamics. J. Cell. Physiol. 214: 334–344, 2008. © 2007 Wiley‐Liss, Inc.
TGF‐β3 inhibits chondrogenesis of cultured chick leg bud mesenchymal cells via downregulation of connexin 43 and integrin β4
Authors: Jin Eun‐Jung , Lee Sun‐Young , Jung Jae‐Chang , Bang Ok‐Sun , Kang Shin‐Sung
Published: July 2007

Transforming growth factor β (TGF‐β) is a multifunctional cytokine that regulates a number of biological responses including chemotaxis, cell cycle progression, differentiation, and apoptosis of cells. Even though temporal and spatial expression of TGF‐β3 suggests its role in chick limb development, it is not well characterized how TGF‐β3 regulates chondrogenic differentiation of limb bud mesenchymal cells. In this study, differential display polymerase chain reaction (DD‐PCR) screening and reverse transcription PCR analysis revealed that the mRNA expression of the gap junction protein, connexin 43 (Cx43), was significantly decreased during the first treatment of TGF‐β3 for 24 h in cultured chick leg bud mesenchymal cells. Treatment of these cells with lindane, a general gap junction blocker, or expression of dominant negative Cx43 increased apoptotic cell death and decreased the level of integrin β4 protein, in a manner similar to that observed when these cells were exposed to TGF‐β3. Similarly, exposure of cultured leg chondroblasts to a functional blocking antibody against integrin‐β4 induced an increase in apoptosis. Treatment of cells with TGF‐β3 decreased the membrane translocation of PKC‐α, leading to activation of ERK. The increase in apoptotic cell death triggered by TGF‐β3 and dominant negative Cx43 was blocked by inhibition of ERK but increased by inhibition of PKC. Collectively, these data indicate that, in cultured chick leg bud mesenchyme cells, TGF‐β3 treatment downregulates Cx43 and induces apoptotic cell death via downregulation of integrin β4, activation of ERK and suppression of PKC‐α activation. J. Cell. Physiol. 214: 345–353, 2008. © 2007 Wiley‐Liss, Inc.
Evidence of force exchanges during the six‐legged walking of the bottom‐dwelling fish, Chelidonichthys lucerna
Authors: Jamon Marc , Renous Sabine , Gasc Jean Pierre , Bels Vincent , Davenport John
Published: July 2007

Locomotion in terrestrial vertebrates is supposed to be derived from preadaptation in bottom‐dwelling fish. A few fish species have been assumed to walk on the substratum, on the basis of coordinated movements of their paired fins. However, the validity of this assumption has remained uncertain, because of a lack of evidence that their fin rays actually exert a force on the substratum. Here, we provide the first conclusive evidence that a benthic teleost fish, the gurnard, Chelidonichthys lucerna (Triglidae), exerts forces on the substratum during its temporary bottom‐dwelling hexapod locomotion. This demonstration was achieved by the use of a photoelastic gel technique combined with a force calibration device. The movement patterns of the three first pairs of rays of the pectoral fins were analysed in relation to the forces exerted on the substratum, by measuring deformations of the photoelastic gel substratum produced by the rays. The rays were shown to produce a force pattern that confirmed the existence of a hexapod locomotion in a vertebrate that was consistent with body propulsion and voluntary substratum walking. J. Exp. Zool. 307A:542–547, 2007. © 2007 Wiley‐Liss, Inc.
Wing morphology and flight behavior of pelecaniform seabirds
Authors: Brewer Michael L. , Hertel Fritz
Published: July 2007

The selective pressures associated with flight are significant factors in shaping the morphology of volant forms. Tropical seabirds are of particular interest because of their long foraging bouts, which can last hundreds of kilometers in search of unpredictable (spatially and temporally) resources. Here, we contrast wing loading (WL), aspect ratio (AR), and planform shape among five pelecaniform seabirds and correlate morphological diversity with known differences in flight strategies. Overall, WL and AR scaled with body mass. The Great Frigratebird had lower WL than that predicted, whereas the Red‐tailed Tropicbird had higher WL than that predicted. The tropicbird also exhibited a lower AR than that predicted. Visualization of planform shape was accomplished by using Thin‐plate spline relative warp analysis (TPS/RWA), and three major regions of variations were discovered: wing base, mid‐wing, and distal wing/wing tip. As expected, the three boobies were more similar than either the tropicbird or the frigatebird. The tropicbird had a broader distal wing and more rounded wing tip, associated with its greater use of flapping flight. The frigatebird showed the greatest deviation in the distal wing and wing tip associated with the high maneuverability required for aerial pursuit and kleptoparasitism. By using TPS/RWA, important differences were detected in planform shape that would have otherwise gone unnoticed when using only WL and AR. These differences correlated strongly with parameters such as maneuverability, flapping, and soaring flight. J. Morphol., 2007. © 2007 Wiley‐Liss, Inc.
Translating business strategies into action: Managing strategic change
Authors: Stace Doug A. , Dunphy Dexter C.
Published: July 2007

In a volatile business environment, few would argue that the central task of management is the management of change. Yet how to formulate an overall change strategy, particularly one that has overall synergy with an organization's business strategies, has proven to be more difficult. This article describes the results obtained from an intensive and comprehensive field research study, which attempted to trace the linkages between an organization's business strategies, its organizational change strategies and its human resource (HR) strategies. We were interested to see if patterns of co‐alignment could be identified between these three areas. The results of the study provide an alternate framework to the almost universalist prescriptions for incremental and con‐sultatively based organizational change that is so dominant in management literature. We provide a situational model of change strategies, relating it with generic business strategies on the one hand and with a model of HR management strategies on the other. These models combined provide an integrated view of management strategies that are designed to ensure that business strategy repositioning is not only planned, but also effectively implemented.
Planning in a turbulent environment: How to organize your planning process
Authors: Piëst Bert
Published: July 2007

For planning to be effective, there should be alignment between the characteristics of the planning process and the level of environmental turbulence. The logical consequence is that planning processes should be altered due to changing environmental conditions. This article describes how planning can be organized given a certain level of environmental turbulence. A planning audit is given to monitor the effectiveness of the planning process and it is used to describe which conditions must be satisfied to enable the process of strategic planning to be changed.
Macromol. Mater. Eng. 7/2007
Authors: Müller‐Buschbaum Peter , Ittner Thilo , Maurer Edith , Körstgens Volker , Petry Winfried
Published: July 2007

Cover: The picture on the cover shows an in‐situ characterisation of a pressure sensitive adhesive film with the mechanical tack test and synchrotron radiation based ultra small angle scattering. This combination allows to tailor the adhesive properties and to understand the de‐bonding mechanism. Further details can be found in the article by P. Müller‐Buschbaum,* T. Ittner, E. Maurer, V. Körstgens, and W. Petry on page 825.
First Principle Simulations of Ethylene Glycol Addition to Diisocyanates
Authors: Cysewski Piotr , Król Piotr , Shyichuk Alexander
Published: July 2007

The reaction of addition of ethylene glycol to diisocyanates was studied with the B3LYP method to gain an insight into the mechanism of polyurethane synthesis. It was found that the functional basis set should contain at least one diffusion function for the simulation in order to properly describe thermo‐chemical features of the model reaction. Using the B3LYP/6‐31+G** level the values of Gibbs free energy were estimated for the addition reaction of ethylene glycol to toluene‐2,4‐diisocyanate, toluene‐2,6‐diisocyanate, diisocyanate‐[5‐isocyanato‐1‐(isocyanatomethyl)‐1,3,3‐trimethylcyclohexane], 1,6‐diisocyanatohexane, 4,4′‐methylenebis(cyclohexyl isocyanate) and methylenebis(phenyl isocyanate). Both the gaseous phase and the benzene environment were taken into consideration. Spontaneity of the reaction proved to be dependent on both substrate type and product isomeric configuration. The trans‐urethane isomer has been found to be a more stable product. Considering the values of activation energy the minor dependence on the structure of diisocyanate was observed. This confirmed Flory's postulate to be valid for the polyurethane synthesis. The highest value of activation energy was found for the first stage, which consists of ethylene glycol approach and simultaneous proton transfer to the isocyanate group. For that reason the first stage has been estimated as that limiting the general rate of the urethanisation reaction.

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Asymptotics for steady‐state voltage potentials in a bidimensional highly contrasted medium with thin layer
Authors: Poignard Clair
Published: July 2007

We study the behaviour of steady‐state voltage potentials in two kinds of bidimensional media composed of material of complex permittivity equal to 1 (respectively, α) surrounded by a thin membrane of thickness h and of complex permittivity α (respectively, 1). We provide in both cases a rigorous derivation of the asymptotic expansion of steady‐state voltage potentials at any order as h tends to zero, when Neumann boundary condition is imposed on the exterior boundary of the thin layer. Our complex parameter α is bounded but may be very small compared to 1, hence our results describe the asymptotics of steady‐state voltage potentials in all heterogeneous and highly heterogeneous media with thin layer. The asymptotic terms of the potential in the membrane are given explicitly in local coordinates in terms of the boundary data and of the curvature of the domain, while these of the inner potential are the solutions to the so‐called dielectric formulation with appropriate boundary conditions. The error estimates are given explicitly in terms of h and α with appropriate Sobolev norm of the boundary data. We show that the two situations described
above lead to completely different asymptotic behaviours of the potentials. Copyright © 2007 John Wiley & Sons, Ltd.
A weighted Lq‐approach to Oseen flow around a rotating body
Authors: Farwig R. , Krbec M. , Nečasová Š.
Published: July 2007

We study time‐periodic Oseen flows past a rotating body in ℝ3 proving weighted a priori estimates in Lq‐spaces using Muckenhoupt weights. After a time‐dependent change of coordinates the problem is reduced to a stationary Oseen equation with the additional terms (ω ∧ x) ⋅ ∇ u and −ω ∧ u in the equation of momentum where ω denotes the angular velocity. Due to the asymmetry of Oseen flow and to describe its wake we use anisotropic Muckenhoupt weights, a weighted theory of Littlewood–Paley decomposition and of maximal operators as well as one‐sided univariate weights, one‐sided maximal operators and a new version of Jones' factorization theorem. Copyright © 2007 John Wiley & Sons, Ltd.
Calculation of radial‐line microwave filters
Authors: Rydberg Anders
Published: July 2007

We have compared theoretical and experimental performance of microwave radial‐line filters using air or teflon dielectrics. We found good agreement, with errors in the calculation of the resonance frequency of less than 1% for impedances in the range 10‐80 ω.
Slotline fed microstrip antenna array modules
Authors: Lo Y. T. , Oberhart M. L. , Brenneman J. S. , Aoyagi P. , Moore J. , Lee R. Q. H.
Published: July 2007

A feed network comprised of a combination of coplanar waveguide and slot transmission line is described for use in an array module of four microstrip elements. Examples of the module incorporating such networks are presented as well as experimentally obtained impedance and radiation characteristics.
Computer simulation of atmospherically corrupted signals at the focal plane of a parabolic antenna
Authors: Sitterle Jeffrey J. , Claspy Paul C. , Merat Francis L.
Published: July 2007

A simulation procedure for generating the signals appearing at the focal plane of a parabolic reflector is presented. The procedure consists of generating the time series of the angle‐of ‐arrival fluctuation and intensity scintillation directly from their temporal power spectra and combining the two processes. An example of the procedure is also given.
The spectral discretization of transmission line system
Authors: Palusinski O. A. , Lee Anyu
Published: July 2007

The interconnections used in packaging of modern circuits introduce the delays that are comparable or even greater than the delays of gates. This causes the degradation of overall system performance. One may choose to solve the problem of delay by increasing the density of the system. This, however, introduces the problem of “crosstalk.” The analysis of delay and crosstalk in a system of interconnections requires the use of computer simulation. This paper introduces a very efficient and flexible time‐domain analysis technique to predict the reflections and crosstalks. Numerical results show that this technique is indeed efficient and accurate in the transient analysis of general multiple coupled‐line systems. The algorithm yields an equivalent linear hybrid n‐port network for the interconnection system that facilitates the analysis of interconnections together with driving and receiving circuits with the aid of standard network analyzers like, for example, SPICE.
11‐ghz fiber optic links for airborne satellite communications applications
Authors: Gee C. M. , Thurmond G. D. , Newberg I. L. , Yen H. W. , Lafaw D. , Spink B.
Published: July 2007

We report the first implementation of fiber optics at 11 GHz in an experimental satellite communication EHF/SHF research terminal for airborne applications. Signal‐to‐noise and bit‐error rate were measured to characterize the system after a 100‐m‐long fiber optic link replaced a 4‐ft‐long coaxial cable to enable X‐band signal remoting.
Quasihomogeneous sources with longitudinal periodicity
Authors: Ojeda‐Castañeda J. , Pons A.
Published: July 2007

Free‐propagation of the mutual intensity function on the paraxial approximation is expressed by a differential operator, which is applied to identify planar quasihomogeneous sources that have mutual intensities with longitudinal periodicity. Our formula describes in a simple, yet formal, way the formation of Lau bands at finite distances.
A simple and effective method for waveguides loaded with lossy dielectrics or magnetic materials
Authors: Yansheng Xu
Published: July 2007

In this paper an improved method is presented for waveguides loaded with lossy dielectric or magnetic materials. The accuracy of this method is shown for waveguides with three different types of filling.
The calculation of the nearfield of curved edge paraboloid
Authors: Mao Yukuan , Shao Jiangda
Published: July 2007

The SWE method is used to calculate the nearfield distribution at any point in front of a curved edge symmetrical paraboloid. Comparing the results with those from the GTD method, we find that without correction, using the physical optics current approximation, we can get relatively accurate nearfield distribution in front of the dish.
Pure bending‐induced birefringence in optical waveguides: A simple analytical expression
Authors: Cheng Y. H. , Lin W. G.
Published: July 2007

The local field in the bent optical waveguide and the birefringence caused by the pure bent geometry effect are investigated. It is found that, this birefringence is independent of the local field in the bent guide and only dependent on the unperturbed propagation constant and the radius of the guide bend.
Optimization of the gap geometry in ultrafast optoelectronic switching experiments
Authors: Bergner H. , Brueckner V. , Lenzner M. , Strobel R.
Published: July 2007

In order to increase the output voltages of optoelectronic switches the influence of the gap geometry of these devices on the applicable voltage and the switching efficiency is investigated. It is theoretically shown that electrodes with distinctly rounded corners cause a maximum output signal at a given biased voltage. Experimental results are presented for semicircular and rectangular electrodes.
Measuring phase retardation of wave plates: A NOVEL TECHNIQUE
Authors: Yao Lin , Zhiyao Zhou , Runwen Wang
Published: July 2007

This paper proposes and discusses an optical heterodyne technique to measure the phase retardation of a wave plate. The accuracy of this measurement technique in determining the optical path difference of a quarter wave plate is smaller than the wavelength of light source divided by 6000, exceeding the accuracies of other measurement techniques.
Finite‐element matrices for loss calculation in quasi‐tem analysis of microwave transmission lines
Authors: Pantić‐Tanner Zorica , Mittra Raj
Published: July 2007

Finite‐element matrices for loss calculation of a dominant quasi‐TEM mode propagating along a uniform transmission line are given. These matrices refer to Nth‐order polynomial expansions of the field and are independent of the shape of the triangular element. The dielectric and conductor losses are calculated using a perturbational approach.
On volume modes and surface modes in partial‐height ferrite circulators and their bandwidth expansion at millemeter wave band
Authors: Dou W. B. , Li S. F.
Published: July 2007

The electromagnetic field modes in partial‐height ferrite circulators are classified into two categories: volume modes and surface modes. Their properties are described in detail. The method of expanding the circulator bandwidth at the millimeter wave band is investigated. A set of theoretical results are calculated for a n = 2 Chebyshev response. A Ka‐band circulator is designed. The measured minimum isolation is 15 dB over a 9‐GHz bandwidth. The experimental result and theoretical prediction are similar.
Dielectric‐loaded circular ridge waveguide applicator for hyperthermia
Authors: Beckman C. , Lundgren L. , Roos D.
Published: July 2007

An applicator for intracavitary hyperthermia treatment of cancer has been designed and tested. The applicator is a section of a dielectric‐loaded circular ridge waveguide closed at both ends to form a transmission cavity. An aperture in the cavity wall can produce a directed heating of a tumor growing in the wall of a body cavity such as the vagina.
Analysis of decision‐driven loop‐based receivers for optic fiber bpsk homodyne systems
Authors: Xiao‐pin Zhang , Peida Ye
Published: July 2007

Decision‐driven PLL is analyzed for optic fiber BPSK homodyne detection systems. The effects of laser linewidth and detector shot noise are considered. The optimization and selection of the loop parameters are discussed.
Radar applications of 10‐GHZ fiber optic links
Authors: Newberg I. L. , Gee C. M. , Thurmond G. D. , Yen H. W.
Published: July 2007

Long delay lines can improve the performance and flexibility of radar test sets. Using a 2.25‐km‐long fiber optic link, we demonstrated generation of an ideal target for a radar repeater test set and measurement of phase noise closer than 100 Hz to a 9.6‐GHz radar carrier signal using a delay line discriminator phase‐noise test set.
Adaptive array radar data processing using the bimodal optical computer
Authors: Abushagur Mustafa A. G.
Published: July 2007

The use of the bimodal optical computer (BOC) in determining the weights for an adaptive phased array radar is introduced. Interference canceling is presented for two cases: (1) assuming the direction of the jammer is known and (2) assuming no a priori information. The effect of the jammers on the array pattern is shown for up to four jammers.
Comparisons of the application of various conjugate‐gradient algorithms to electromagnetic radiation from conducting bodies of revolution
Authors: Davidson David B. , McNamara Derek A.
Published: July 2007

Descriptions are given of the application of the classical conjugate‐gradient (CG) matrix solution algorithm and variants thereof (three types of preconditioner and the biconjugate gradient method) to the matrix equations obtained on application of the moment method to the reduced subproblems describing radiation from conducting bodies of revolution, and the associated numerical results. A recent debate in the literature on the interpretation of the application of CG methods to electromagnetic problems is put in perspective.
Efficient characterization of multilevel interconnections on the gaas‐based VLSICs
Authors: Goel A. K. , Huang Y. R.
Published: July 2007

An efficient numerical technique for the characterization of the single‐and multi‐level interconnections on the GaAs‐based VLSIs is presented. The algorithm employs an efficient and more flexible network analog method suitable for the finite‐dimensional interconnection configurations on the GaAs substrate.
Characteristic impedance of a curved microstrip transmission line
Authors: Roy J. S. , Poddar D. R. , Mukherjee A. , Chowdhury S. K.
Published: July 2007

Modification of Wheeler's expression for the characteristic impedance of a straight microstrip transmission line is derived for the computation of the characteristic impedance of a curved microstrip transmission line. Good agreement between computed and measured data is obtained.
A compact biconical dual‐mode feed for low‐cost offset reflector antennas
Authors: Maniá Lucio , Vatalaro Francesco
Published: July 2007

This paper describes a version of the dual‐model feed horn that is considered particularly suitable for application in receive‐only reflector antennas. Even though it was originally presented many years ago, to the authors' knowledge this type of biconical feed horn has not previously been analyzed or utilized. The present paper aims to describe the potential advantages of this feed horn for low‐cost satellite earth stations, and then briefly to illustrate the design methodology that was adopted. Finally, it presents some of the experimental and theoretical results, which are in good agreement and demonstrate the performance achievable with this class of feeds.
Effective refractive index and single‐transverse mode condition in InGaAsP/InP BH laser diodes
Authors: Ghafoori‐Shiraz H.
Published: July 2007

The effective refractive index and single‐transverse mode condition in three‐layer BH laser diodes operating at 1.3 and 1.55 μm have been investigated for both TE and TM modes. The results can be useful in the design of laser diodes with improved light‐output coupling efficiency into single‐mode fibers and also to determine the corrugation period of DFB lasers.
Heterodyne detection of small angle scattered far‐infrared laser radiation
Authors: Jacobsson Stellan , Hård Sverker
Published: July 2007

A heterodyne detection scheme for far‐infrared small angle scattered laser radiation is reported and demonstrated by measuring the known scattering from a thin wire scatterer. Frequency shifts were on the order of 10 Hz. A Golay cell was used as a detector. The results were compared with theoretical predictions and direct detection data. The method should be useful for scattering measurements of density waves in plasmas.
Computer‐aided design of nonlinear optimum output power mesfet oscillator
Authors: Choo E. B. L. , Stewart J. A. C. , Fusco V. F.
Published: July 2007

Large‐signal MESFET microwave oscillator design is a nontrivial problem, involving nonlinear analysis, or extensive and time consuming load‐pull methods. A computer‐aided oscillator design technique employing nonlinear analysis in conjunction with optimization to identify the device best operating condition, for maximum output power, is described. Experimental verification at Ku band is presented.
A high gain microstrip array adopting EMC dipoles
Authors: Russo P. , Ruggieri M.
Published: July 2007

Samples of microstrip arrays for linear polarization have been developed for operating in the 11.7‐12.5‐GHz frequency range starting from analyses and experiments performed on EMC dipoles and corporate feed boards.

The array analysis approach is discussed together with the results achieved. Further results, obtained for circularly polarized structures, are also presented.

Attractive performance has been achieved, especially in terms of bandwidth and efficiency.
A new model for diffusion from periodical Ti strips into LiNbO3 crystal
Authors: Alexeyev A. N. , Jian‐hui Zhou , Jun‐de Song
Published: July 2007

In this paper, we present a new model for diffusion from periodical Ti strips into LiNbO3 crystal using the depth‐dependent diffusion coefficient.
Self‐steepening effect of optical pulse propagating in kerr medium
Authors: Dingyuan Tang , Peixia Qiu , Fuxin Zhou , Runwen Wang
Published: July 2007

Using a specially designed liquid‐core optical fiber system and Q‐switched optical pulse, we have first experimentally observed the effect of self steepening of the optical pulse caused by the optical Kerr effect. The mechanism and characteristics of this effect have also been analyzed theoretically.
A simple method of dual‐reflector geometrical optics synthesis
Authors: Lee Choon S.
Published: July 2007

A simplified mathematical synthesis of dual reflectors, based on geometrical optics (GO), is presented. In this method, the reflector surfaces are divided into small sections, and each section is assumed to be locally planar. This assumption greatly simplifies the mathematics of reflector synthesis and closed‐form solutions are obtained.
Edge detection using polarization‐encoded optical shadow‐casting
Authors: Awwal A. A. S. , Karim M. A.
Published: July 2007

A very powerful space‐variant image processing technique, namely edge detection, is performed using a polarization‐encoded optical shadow‐casting system.
Finite‐element analysis of anisotropic waveguides with storage reduction and elimination of spurious modes
Authors: Pantic‐Tanner Zorica , Chan Chi Hou , Mittra Raj
Published: July 2007

In this paper we present a finite‐element analysis of waveguides that are inhomogeneously filled with an anisotropic material, which may be either dielectric or magnetic type. The problem is formulated by using the transverse magnetic or electric field components, respectively, for anisotropic dielectric and magnetic materials. The formulation employed eliminates the spurious and nonphysical modes by analytically satisfying the divergence relations and achieves a reduction in the computer storage requirement as well. Numerical results are found to exhibit good agreement with the available data.
A full‐wave solution for the mutual coupling between circular microstrip patch antennas
Authors: Aberle J. T. , Pozar D. M.
Published: July 2007

A full‐wave solution for the mutual coupling between circular microstrip patches fed by idealized vertical probe feeds is presented. The grounded slab Green's function is used together with the moment method to determine the current distribution on each patch. From this, the patch port impedance matrix and, hence, the mutual coupling can be determined. Measured data that validate the theory are presented.
Cutoff frequencies and radial wave numbers of surface wave modes in a multilayered structure
Authors: Bhattacharyya Arun K.
Published: July 2007

Formulations of radial wave numbers and cutoff frequencies for surface wave modes in a multilayered structure on a ground plane are presented Numerical results for one, two, and three layered structures are shown. These results will be useful for determining the existence of possible surface wave modes in a multilayered structure at a given frequency of operation.
Frequency chirping and the impact of 1/f‐type noise in negative electrical feedback semiconductor lasers
Authors: Jianping Zhang , Ling Li , Peida Ye
Published: July 2007

In this letter we will present a complete analysis of frequency chirping in negative electrical feedback (NEFB) semiconductor lasers by using the semiclassical rate equation model. The effects of 1/f‐type FM noise also will be discussed. Our result shows that this kind of noise is an important origin of the linewidth reduction limitation.
Spectral green's functions for a thin, circular, magnetic‐current loop for microstrip VIA hole analysis
Authors: Chan C. H.
Published: July 2007

The full‐wave spectral Green's function for a thin, circular, magnetic‐current loop radiating slightly above the shorted aperture of a microstrip via hole is given. The expression for the electric potential (in the spectral domain) due to the magnetic‐current loop is then derived for both the full‐wave and electrostatic cases.
Analysis and design of extracted pole E‐plane filters
Authors: Mansour R. R. , Fouladian J.
Published: July 2007

This paper presents a rigorous field theory analysis and design of a novel configuration for E‐plane filters. The proposed configuration is suitable for diplexer applications and preserves the desirable features of conventional E‐plane filters. The analysis is based on the mode matching technique, which allows the effect of the higher order modes to be taken into account in the optimization process. The numerical results agree well with the measured data.
Low impedance matching: The radial stub solution
Authors: Giannini F. , Ruggieri M. , Bartolucci G. , Paoloni C.
Published: July 2007

The radial stub as a key microstrip structure to provide low impedance levels with a well‐defined insertion point is proposed. Its characterization through a planar approach provides a superior accuracy, as compared with the simulations attainable from presently available CAD packages. Some experiments have fully confirmed the design. Furthermore, the flexibility of radial lines in replacing both open and shorted straight stubs is demonstrated together with some successful results, achieved through their use in practical applications.
X‐band local oscillator distribution network
Authors: Bharj Sarjit S. , Tan S. P. , Gluck J. , Thompson B.
Published: July 2007

An X‐band local oscillator network has been designed and developed to provide in excess of +8 dBm for four independent channels. The network consists of an X‐band voltage controlled oscillator tunable from 8 to 12 GHz. The output of the oscillator is input to a set of three MMIC in‐phase power splitters with 0 dB gain and excellent phase performance.
Optical implementation of A 2‐D neural net with a third‐order interconnection for image quadratic associative memory based on a compact‐encoding method
Authors: Lin Senmao , Wu Jie , Liu Liren
Published: July 2007

The optical implementations of a 2‐D neural net with a third‐order interconnection for image quadratic associative memory are reported. Two types of incoherent optical systems, based on multiple imaging and correlation, are used. In particular, a compact‐encoding method, which can greatly reduce the size of the interconnection tensor, is also proposed. The experimental results are given.
Equivalent current theory on anisotropic optical fiber
Authors: Rongqing Hui , Yizun Wu , Chaoxiang Shi
Published: July 2007

In this letter we extend the equivalent current theory to optical fibers composed of anisotropic material. Analytical formulas for the radiation loss and the mode coupling in single‐mode single‐polarization fibers have been derived.
Double fsk coherent optical system exploiting the orthogonal polarization modes of a single‐mode fiber
Authors: Betti S. , Curti F. , de Marchis G. , Lannone E.
Published: July 2007

A novel coherent optical system is proposed based on transmission of two FSK modulated signals associated to orthogonal polarization states of a single‐mode fiber. At the receiver the transmitted signals are separated by Jones matrix inversion providing insensitivity to polarization fluctuations and allowing the use of two semiconductor lasers at the transmitter.