bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extremely Color‐Stable Blue Light‐Emitting Polymers Based on Alternating 2,7‐Fluorene‐co‐3,9‐carbazole Copolymer
Authors: Liu Ransheng , Xiong Yan , Zeng Wenjin , Wu Zhonglian , Du Bin , Yang Wei , Sun Mingliang , Cao Yong 
Published: July 2007

AbstractNovel alternating 2,7‐fluorene‐co‐3,9‐carbazole copolymer(3,9‐PFCz) was synthesized by Suzuki polycondensation between 3‐bromo‐9‐(2‐iodo‐9,9‐dioctyl‐9H‐fluoren‐7‐yl)‐9H‐carbazole and 2,7‐bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)‐9,9‐dioctylfluorene. Cyclic voltammetry studies showed a higher HOMO level (−5.23 eV) than the polyfluorene homopolymer(PFO). The glass transition temperature of the copolymer (110 °C) was much higher than that of the PFO (67 °C). After the copolymer had been annealed at 200 °C for 2 h, the PL spectra showed almost no change and no aggregation‐ or oxidation‐related undesirable long‐wavelength emission has been observed. The light‐emitting diode in configuration of ITO/PEDOT/EML/CsF/Al showed a maximum external quantum efficiency of 1.54% with a luminance of 435 cd · m−2 and the maximum brightness of 2 630 cd · m−2 with CIE coordinate (0.17, 0.14) was achieved at 8.4 V. The device prepared in configuration of ITO/PEDOT/PVK/polymer/Ba/Al exhibits an efficient, stable blue emission; it has a turn‐on voltage of 6 V and maximum external quantum efficiency of 1.1%. The EL emission remains stable at high current density and after thermal treatment at 150 °C for 30 min. Extremely color‐stable blue emission from alternating poly[(2,7‐fluorene)‐co‐(3,9‐carbazole)] copolymer makes it a promising candidate for flat‐panel display applications.magnified image
On Hardy–Steklov and geometric Steklov operators
Authors: Burenkov V. , Jain P. , Tararykova T. 
Published: July 2007

AbstractA new (non‐Muckenhoupt type) weight characterization for the boundedness of the general Hardy–Steklov operator is obtained in the case 1 < p ≤ q < ∞. The estimates obtained for the norm of the Hardy–Steklov operator allow the limiting procedure and as a result the boundedness of the corresponding geometric Steklov operator is investigated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Annihilating polynomials for quadratic forms and Stirling numbers of the second kind
Authors: De Wannemacker Stefan 
Published: July 2007

AbstractWe present a set of generators of the full annihilator ideal for the Witt ring of an arbitrary field of characteristic unequal to two satisfying a non‐vanishing condition on the powers of the fundamental ideal in the torsion part of the Witt ring. This settles a conjecture of Ongenae and Van Geel. This result could only be proved by first obtaining a new lower bound on the 2‐adic valuation of Stirling numbers of the second kind. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gateaux differentiability in Orlicz–Lorentz spaces and applications
Authors: Levis Fabian E. , Cuenya Hector H. 
Published: July 2007

AbstractLet Λw,ϕ be the Orlicz–Lorentz space. We study Gateaux differentiability of the functional ψw,ϕ (f) = $ \int _{0} ^{\infty} $ ϕ (f *)w and of the Luxemburg norm. More precisely, we obtain the one‐sided Gateaux derivatives in both cases and we characterize those points where the Gateaux derivative of the norm exists. We give a characterization of best ψw,ϕ ‐approximants from convex closed subsets and we establish a relation between best ψw,ϕ ‐approximants and best approximants from a convex set. A characterization of best constant ψw,ϕ ‐approximants and the algorithm to construct the best constant for maximum and minimum ψw,ϕ ‐pproximants are given. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electro‐Copolymerization of Layer‐by‐Layer Deposited Polythiophene and Polycarbazole Precursor Ultrathin Films
Authors: Waenkaew Paralee , Taranekar Prasad , Phanichphant Sukon , Advincula Rigoberto C. 
Published: July 2007

AbstractThe synthesis, layer‐by‐layer deposition, and electro‐copolymerization of precursor polyelectrolyte multilayer ultrathin films with thiophene and carbazole electroactive groups are described. The interest is in observing an electrochemical cross‐linking approach towards a highly ordered ultrathin film that contains two types of monomers to result in possible layer‐limited homo‐ and copolymerization. A uniform linear growth with alternate deposition of the polyelectrolytes is observed. The multilayer films were then electrochemically polymerized anodically by cyclic voltammetry (CV), which results in copolymerization between two different electroactive groups. Cross‐linking of the layers was verified by CV and spectroelectrochemistry data with very good linear electro‐copolymerizability.magnified image
Molecular Dynamics Simulations of Helium Permeation in Polyimides with a Bulky Dianhydride and a Fluorinated Diamine
Authors: Neyertz Sylvie 
Published: July 2007

AbstractFully‐atomistic molecular dynamics (MD) simulations have been carried out to model helium transport through four different glassy polyimides. While the polymer matrices had been pre‐validated, specific parameters and combination rules were used here in order to describe helium‐helium and helium‐polymer interactions. Gas permeabilities are in very good agreement with experimental evidence. Two ways to decrease chain cohesion and improve gas transport were considered – the replacement of an ODPA by a bulky BCDA dianhydride, and the substitution of a site on an ODA diamine by a CF3. The fluorinated polyimide appears to be the most promising material with more heterogeneity in the void‐space distribution, the highest model permeability and fewer constraints from an experimental point of view.magnified image
Microarray analysis reveals that leptin induces autocrine/paracrine cascades to promote survival and proliferation of colon epithelial cells in an Apc genotype‐dependent fashion
Authors: Fenton Jenifer I. , Lavigne Jackie A. , Perkins Susan N. , Liu Huaitian , Chandramouli Gadisetti V.R. , Shih Joanna H. , Hord Norman G. , Hursting Stephen D. 
Published: July 2007

AbstractThe imbalance in systemic mediators of inflammation, such as leptin, is thought to be involved in obesity‐associated cancers. In addition, systemic endocrine signals can influence the local autocrine/paracrine factors produced within this microenvironment to influence epithelial cell fate. We previously demonstrated that leptin preferentially promotes the survival and proliferation of colon epithelial cells possessing an Apc mutation (IMCE) but not model normal cells (YAMC). Therefore, the purpose of this study was to identify leptin‐induced functional gene family changes which characterize the response of colon epithelial cells possessing an Apc mutation but not normal cells. Consistent with our knowledge of colon carcinogenesis, genes regulating the Wnt/β‐catenin‐mediated pathway including Mdm2, Pik3r1, and Rb1 were upregulated by leptin. Importantly, leptin induced IGF‐mediated pathway gene expression changes and their protein products in IMCE cells. In the IMCE cells IGFBP‐6, IGF‐1, and Crim1 expression was upregulated, while IGFBP‐2, IGFBP‐3, IGFBP‐4, IGFBP‐5, and Nov expression was downregulated by leptin treatment. These data establish a biologically plausible mechanistic link between the elevated levels of growth factors and the increased risk of colon cancer associated with obesity. © 2007 Wiley‐Liss, Inc.
Transcriptome analysis of serous ovarian cancers identifies differentially expressed chromosome 3 genes
Authors: Birch Ashley H. , Quinn Michael C.J. , Filali‐Mouhim Ali , Provencher Diane M. , Mes‐Masson Anne‐Marie , Tonin Patricia N. 
Published: July 2007

AbstractCytogenetic, molecular genetic and functional analyses have implicated chromosome 3 genes in epithelial ovarian cancers (EOC). To further characterize their contribution to EOC, the Affymetrix U133A GeneChip® was used to perform transcriptome analyses of chromosome 3 genes in primary cultures of normal ovarian surface epithelial (NOSE) cells (n = 14), malignant serous epithelial ovarian tumors (TOV) (n = 17), and four EOC cell lines (TOV‐81D, TOV‐112D, TOV‐21G, and OV‐90). A two‐way comparative analysis of 735 known genes and expressed sequences identified 278 differentially expressed genes, where 43 genes were differentially expressed in at least 50% of the TOV samples. Three genes, RIS1 (at 3p21.31), GBE1 (at 3p12.2), and HEG1 (at 3q21.2), were similarly underexpressed in all TOV samples. Deregulation of the expression of these genes was not associated with loss of heterozygosity (LOH) of the genetic loci harboring them. LOH analysis of the RIS1, GBE1, and HEG1 loci was observed at frequencies of 14.3%, 13.7%, and 9.2%, respectively, in a series of 66 malignant TOV samples of the serous subtype. Reduced expression levels of RIS1, GBE1, and HEG1 were observed only in the tumorigenic EOC cell lines (TOV‐21G, TOV‐112D, and OV‐90) and did not correlate with LOH. These results combined suggest that RIS1, GBE1, and HEG1, unlike classical tumor suppressor genes, are not likely to be primary targets of inactivation. This study provides a comprehensive analysis of chromosome 3 gene expression in NOSE and in EOC samples and identifies chromosome 3 gene candidates for further study. © 2007 Wiley‐Liss, Inc.
Hypermethylation status of APC inversely correlates with the presence of submucosal invasion in laterally spreading colorectal tumors
Authors: Hashimoto Kazuo , Shimizu Yoshihisa , Suehiro Yutaka , Okayama Naoko , Hashimoto Shinichi , Okada Toshiyuki , Hiura Mikako , Ueno Koji , Hazama Shoichi , Higaki Shingo , Hamanaka Yuichiro , Oka Masaaki , Sakaida Isao , Hinoda Yuji 
Published: July 2007

AbstractLittle is known about epigenetic alterations in laterally spreading colorectal tumors (LSTs). The goal of the present study was to elucidate the epigenetic background of LSTs and compare the methylation status of DNA CpG islands (CGIs) with clinicopathologic features. Methylation of MINT1, MINT2, MINT31, p16, O6‐methylguanine‐DNA methyltransferase (MGMT), adenomatous polyposis coli (APC), and human MutL homologue 1 (hMLH1) in 42 LSTs was assessed by methylation‐specific polymerase chain reaction (MSP) and compared with clinicopathologic parameters. The frequency of hypermethylation was 12.5% (4/32) for MINT1, 40.0% (16/40) for MINT2, 25.0% (10/40) for MINT31, 25.7% (9/35) for p16, 7.7% (3/39) for hMLH1, 26.5% (9/34) for MGMT, and 35.9% (14/39) for APC. APC methylation was inversely associated with submucosal invasion (P = 0.034), which was not found in any of 14 LST cases with APC methylation, whereas submucosal invasion was present in 8 of 25 (32.0%) cases without APC methylation. These data suggest that hypermethylation of APC could be a predictive marker for the absence of submucosal invasion of LSTs. © 2007 Wiley‐Liss, Inc.
BRCA1 and acetyl‐CoA carboxylase: The metabolic syndrome of breast cancer
Authors: Brunet Joan , Vazquez‐Martin Alejandro , Colomer Ramon , Graña‐Suarez Begoña , Martin‐Castillo Begoña , Menendez Javier A. 
Published: July 2007

AbstractBreast cancer‐associated mutations affecting the highly‐conserved C‐terminal BRCT domains of the tumor suppressor gene breast cancer susceptibility gene 1 (BRCA1) fully disrupt the ability of BRCA1 to interact with acetyl coenzyme A carboxylase alpha (ACCA), the rate‐limiting enzyme catalyzing de novo fatty acid biogenesis. Specifically, BRCA1 interacts solely with the phosphorylated (inactive) form of ACCA (P‐ACCA), and the formation of the BRCA1/P‐ACCA complex interferes with ACCA activity by preventing P‐ACCA dephosphorylation. One of the hallmarks of aggressive cancer cells is a high rate of energy‐consuming anabolic processes driving the synthesis of lipids, proteins, and DNA (all of which are regulated by the energy status of the cell). The ability of BRCA1 to stabilize the phosphorylated/inactive form of ACCA strongly suggests that the tumor suppressive function of BRCA1 closely depends on its ability to mimic a cellular‐low‐energy status, which is known to block tumor cell anabolism and suppress the malignant phenotype. Interestingly, physical exercise and lack of obesity in adolescence have been associated with significantly delayed breast cancer onset for Ashkenazi Jewish women carrying BRCA1 gene mutations. Further clinical work may explore a chemopreventative role of “low‐energy‐mimickers” deactivating the ACCA‐driven “lipogenic phenotype” in women with inherited mutations in BRCA1. This goal might be obtained with current therapeutic approaches useful in treating the metabolic syndrome and associated disorders in humans (e.g., type 2 diabetes and obesity), including metformin, thiazolidinediones (TZDs), calorie deprivation, and exercise. Alternatively, new forthcoming ACCA inhibitors may be relevant in the management of BRCA1‐dependent breast cancer susceptibility and development. © 2007 Wiley‐Liss, Inc.
N‐way MMIC redundant switch
Authors: Bahl Inder J. , Griffin Edward L. , Willems David A. 
Published: July 2007

AbstractA novel approach to provide redundancy in an N‐way MESFET switch has been invented and realized with monolithic microwave integrated circuit technology. This switch circuit uses series and shunt FETs configured in a manner to prevent failure of the switch even if several FETs fail. For example, a SPDT redundant switch is capable of providing 1.3‐dB insertion loss and return loss and isolation better than 20 and 35 dB, respectively, over dc to 12 GHz, even if 25% of the FETs fail in each arm.
Compact, broadband double‐slot waveguide radiator
Authors: Kisliuk M. , Axelrod A. , Maoz J. 
Published: July 2007

AbstractA compact, broadband double‐slot waveguide antenna is presented. The present design is an improvement of another double‐slot waveguide radiator proposed earlier by the authors. The antenna is characterized by high efficiency and moderate (less than 2.5:1) VSWR in more than 38% frequency band.
A phase‐noise‐compensating transmission method for phase‐modulated coherent optical systems
Authors: Betti S. , Curti F. , De Marchis G. , Iannone E. 
Published: July 2007

AbstractA new method capable of overcoming the limitations in coherent optical systems that occur when the optical source has a nonnegligible linewidth is proposed. The transmission of a reference signal derived from a common source allows the use of high‐power laser sources which are required in long‐haul optical systems.
Solutions of some transmission lines
Authors: Lin Weigan , Changhua Wan 
Published: July 2007

AbstractSolutions of the unscreened slab line, the triangular slab line, the square slab line, and the hexagonal slab line are obtained by means of conformal mapping and the continuity of electric potential. Both the method and the results are new. All the solutions are believed to be virtually exact for all ranges of the ratio of the dimensions.
A periodic nonlinear analysis technique for microwave mixers
Authors: Smith I. , Richardson J. R. , Miles R. E. 
Published: July 2007

AbstractA general, iterative method is described for obtaining voltage and current waveforms in a periodically driven nonlinear active circuit. This allows local oscillator modulation of the parameters of device models to be studied. The technique is applicable to both diode and FET circuit models, since it can accommodate multiple nonlinearities.
All‐optical logic gates using colloids
Authors: Chowdhury A. H. , Ackerson B. J. , Wood F. , Karim M. A. , Awwal A. A. S. 
Published: July 2007

AbstractAn all‐optical technique is used to realize three logic operations, AND, X‐OR, and NOT. The logic inputs are represented by laser beams that are made to cross in a sample of polymer microspheres at predetermined angles.
Inelastic scattering of gaussian beams by active molecules embedded in a sphere
Authors: Wang Zhi‐Liang , Lin Wei‐Gan 
Published: July 2007

AbstractWhen an electromagnetic wave is incident on a dielectric body filled with active molecules, there also will be inelastically scattered waves in addition to elastically scattered waves. In this paper, making use of the expansion of vector spherical wave functions of Gaussian beams and the method of dyadic Green's functions, we analyze the problem of inelastic scattering of Gaussian laser beams by active molecules embedded in a two‐layer concentric sphere and we also give some numerical results for the first time.
On spot sizes of 1.3 ‐1.55‐μm InGaAsP/InP semiconductor laser diodes
Authors: Ghafoori‐Shiraz H. 
Published: July 2007

AbstractThe spot sizes for the fundamental TE modes of InGaAsP / InP laser diodes in directions parallel and perpendicular to the junction plane have been investigated based on the effective refractive index approach. The analytical results are in good agreement with the reported measured values in the literature. The results can be used to calculate the coupling efficiency between laser diodes and single‐mode fibers.
Scattering parameters of a step discontinuity in a suspended microstrip line
Authors: Picon Odile , Achkar Joseph , Hanna Victor Fouad , Citerne Jacques 
Published: July 2007

AbstractThe dominant and first nine higher‐order modes in a suspended micro‐strip lines are accurately described from a thorough spectral‐domain approach. Then coupling coefficients between eigenmodes at a step width discontinuity to be used in the generalized scattering matrix formulation are directly computed in the spectral domain. Scattering parameters of the dominant mode in the Ka band are presented.
Analysis of transmission structure with periodically loaded elliptical (oval) bars between parallel ground planes
Authors: Rao K. V. Seshagiri , Bhartia Prakash 
Published: July 2007

AbstractThe even and odd mode impedances are determined for the case of a structure consisting of elliptic bars located symmetrically between two infinite parallel plates with a periodic spacing along the width of the parallel plates using conformal transformation. Different compression ratios of the elliptic configuration of the center conductor are considered along with special cases like horizontal strip, circular bar, and vertical strip. The coupling between two adjacent conductors has been determined as a function of the dimensions of the center conductor for different spacings between the conductors. The results of the present analysis are compared with some of those special cases available in the literature.
Mode coupling in on‐fiber devices
Authors: Shankar P. Mohana 
Published: July 2007

AbstractOn‐fiber devices are fabricated by removing the cladding over a short length of the multimode fiber and replacing it with an active medium like electrooptic or magnetooptic material. When a field is applied, the index of this modified cladding goes up, leading to a redistribution of modal amplitudes, which may or may not be accompanied by optical power loss due to radiation modes. Significant optical power loss occurs when the induced index change is large while modal redistribution of amplitudes takes place with negligible power loss when the index change is very small. This modal redistribution has been investigated and expressions for the amplitude coupling coefficient related the modal amplitudes before and after the application of the field are derived. These coupling coefficients have been evaluated as a function of the induced index change in the cladding. The results indicate that this modal redistribution may be used as a sensing mechanism.
Analysis of self‐admittance of a longitudinal shunt slot radiating into a parallel plate region
Authors: Forooraghi Keyvan 
Published: July 2007

AbstractA single longitudinal shunt slot in a rectangular waveguide radiating into a parallel plate region is analyzed. An expression for the magnetic field in the parallel plate region is obtained by developing a Green's function for this region. The slot admittance is computed. The subsequent formulation involves derivation of an integral equation which is solved by the method of moments. Good agreement with measurements has been established.
Local field in a bent step‐index slab waveguide
Authors: Cheng Y. H. , Lin Weigan 
Published: July 2007

AbstractThe local field, field shift, and perturbation correction to the propagation constant in a bent slab waveguide with symmetric step‐index profile are investigated by using local field theory. Simple analytical expressions are given to describe the local fields in the bent slab waveguide for TE and TM modes. An implicit equation is given for the shift of the field maximum of the TE0 fundamental mode.
A theoretical and experimental investigation on millimeter‐wave quantum well oscillators
Authors: Rydberg Anders , Grönqvist Hans , Kollberg Erik 
Published: July 2007

AbstractThe operation and FM noise of millimeter‐wave quantum well (QW) oscillators in a harmonic mode (relaxation oscillations) and a fundamental mode using post and cap waveguide mount structures are investigated. Harmonics up to the ninth harmonic was detected. State of the art results for QW oscillators registered were 84 μW (at 77 K physical temperature) and 60 μW at 90 GHz and 1 μW at 176 GHz (at 300 K physical temperature, respectively).
Folded radial‐line filters
Authors: Baños‐Polglase J. D. , Rebollar J. M. 
Published: July 2007

AbstractIn this article a new structure is proposed to substitute radial‐line filters, particularly for low rejection‐frequency applications, where the cross section of these filters becomes inconveniently large. A very accurate method based on modal analysis and the GSM concept of generalized two‐port discontinuity is applied to calculate the frequency response of both radial‐line and folded radial‐line filters. Agreement with data available for standard radial‐line filters is excellent. A detailed study of the influence of the different geometrical parameters on the response of folded radial‐line filters is also included.
Vector fourier transform analysis of dielectric‐covered slot in the broad wall of a waveguide
Authors: Rexberg Leonard 
Published: July 2007

AbstractThe resonant length versus offset of a dielectric‐covered narrow square ended slot is studied. The slot, located in the broad wall of a rectangular waveguide, is excited by a single mode. The external field is matched to the internal field by the Galerkin method concept. Corrections due to finite wall thickness are also included.
Single stage branchline couplers reappraised
Authors: Fusco V. F. , Kerlin J. B. D. 
Published: July 2007

AbstractAt present the preferred single stage branchline coupler is the conventional quarter wavelength branchline device. This paper illustrates that the quarter wavelength branchline coupler is a special case of a more general form that allows an infinite range of single stage branchline couplers to be developed for any degree of coupling and for any chosen center frequency. We term these couplers fractional wavelength branchline couplers. It is shown that the characteristics of the fractional wavelength branchline coupler are dependent on the design constraints imposed. The design can be constrained either by choice of branch lengths or by selection of line characteristic impedance. For comparison theoretical and experimental results for bandwidth, coupling, and isolation are shown for an example operating at 10 GHz.
A numerically efficient technique for the method of moments solution of electromagnetic problem associated with planar periodic structures
Authors: Chan C. H. 
Published: July 2007

AbstractA numerically efficient summation technique, using the FFT algorithm, for the calculation of the impedance matrix in the method of moment solution to electromagnetic problems associated with planar periodic structures is presented. Comparisons between the CPU times for the conventional brute‐force summation and the present technique are given.