bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wideband hexagonal‐shape stacked‐patch antenna array with L‐probe feed
Authors: Yang Steven S. L. , Luk K. M. 
Published: July 2004

AbstractA two‐element hexagonal‐shape stacked‐patch antenna array fed by an L‐shaped probe is designed and measured. Experimental results show that the array achieves an impedance bandwidth of 34% (SWR < 1.5)/44% (SWR < 2) and a gain of 11.5 dBi. The far‐field radiation pattern is stable across the operation band. The antenna is attractive for modern mobile‐communications covering several frequency bands. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 77–79, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20379
WDM optical‐source generation using wavelength‐locked FP‐LDs with a spectrally sliced FP‐LD
Authors: Choi Woo‐Jun , Han Sang‐Jin , Kwon Hyuk‐Choon , Han Sang‐Kook 
Published: July 2004

AbstractA downstream transmission using a wavelength‐locked Fabry–Perot laser diode (FP‐LD) with a spectrally sliced FP‐LD as a WDM optical source is presented and experimentally demonstrated for application to a WDM passive optical network (PON) link. A side‐mode suppression ratio (SMSR) of better than 40 dB is achieved by using an amplified and spectrally sliced FP‐LD as an external‐injection optical source. As a result, a downstream transmission of 622 Mb/s using a wavelength‐locked FP‐LD is successfully performed over 25 km. We can verify the feasibility of this method by its characteristics of simplicity, operational ease, and wavelength tunability. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 84–87, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20382
Single machine parallel batch scheduling subject to precedence constraints
Authors: Cheng T.C.E. , Ng C.T. , Yuan J.J. , Liu Z.H. 
Published: July 2004

AbstractWe consider the single machine parallel batch scheduling problems to minimize makespan and total completion time, respectively, under precedence relations. The complexities of these two problems are reported as open in the literature. In this paper, we settle these open questions by showing that both problems are strongly NP‐hard, even when the precedence relations are chains. When the processing times of jobs are directly agreeable or inversely agreeable with the precedence relations, there is an O(n2) time algorithm to minimize the makespan. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004
An efficient numerical method for the resolution of the Kirchhoff‐Love dynamic plate equation
Authors: Bécache Eliane , Derveaux Grégoire , Joly Patrick 
Published: July 2004

AbstractWe solve numerically the Kirchhoff‐Love dynamic plate equation for an anisotropic heterogeneous material using a spectral method. A mixed velocity‐moment formulation is proposed for the space approximation allowing the use of classical Lagrange finite elements. The benefit of using high order elements is shown through a numerical dispersion analysis. The system resulting from this spatial discretization is solved analytically. Hence this method is particularly efficient for long duration experiments. This time evolution method is compared with explicit and implicit finite differences schemes in terms of accuracy and computation time. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
Primary and secondary crystallization kinetic analysis of nylon 1212
Authors: Ren Minqiao , Song Jianbin , Zhao Qingxiang , Li Yuesheng , Chen Qingyong , Zhang Hongfang , Mo Zhishen 
Published: July 2004

AbstractThe isothermal and non‐isothermal melt‐crystallization kinetics of nylon 1212 were investigated by differential scanning calorimetry. Primary and secondary crystallization behaviors were analysed based on different approaches. The results obtained suggested that primary crystallization under isothermal conditions involves three‐dimensional spherulite growth initiated by athermal nucleation, while under non‐isothermal conditions, the mechanism of primary crystallization is more complex. Secondary crystallization displays a lower‐dimensional crystal growth, both in the isothermal and non‐isothermal processes. The crystallite morphology of nylon 1212, isothermally crystallized at various temperatures, was observed by polarized optical microscopy. The activation energies of crystallization under isothermal and non‐isothermal conditions were also calculated based on different approaches. Copyright © 2004 Society of Chemical Industry
Thermal analysis of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) irradiated under vacuum
Authors: Yang Huili , Liu Jingjiang 
Published: July 2004

AbstractPoly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) was irradiated by 60Co γ‐rays (doses of 50, 100 and 200 kGy) under vacuum. The thermal analysis of control and irradiated PHBV, under vacuum was carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile properties of control and irradiated PHBV were examined by using an Instron tensile testing machine. In the thermal degradation of control and irradiated PHBV, a one‐step weight loss was observed. The derivative thermogravimetric curves of control and irradiated PHBV confirmed only one weight‐loss step change. The onset degradation temperature (To) and the temperature of maximum weight‐loss rate (Tp) of control and irradiated PHBV were in line with the heating rate (°C min−1). To and TP of PHBV decreased with increasing radiation dose at the same heating rate. The DSC results showed that 60Co γ‐radiation significantly affected the thermal properties of PHBV. With increasing radiation dose, the melting temperature (Tm) of PHBV shifted to a lower value, due to the decrease in crystal size. The tensile strength and fracture strain of the irradiated PHBV decreased, hence indicating an increased brittleness. Copyright © 2004 Society of Chemical Industry
Investigation on odd‐odd nylons based on undecanedioic acid: 1. Synthesis and characterization
Authors: Cui Xiaowen , Li Weihua , Yan Deyue 
Published: July 2004

AbstractA series of odd‐odd polyamides were prepared through step‐heating melt‐polycondensation of undecanedioic acid with various diamines. The synthesized nylons were characterized comprehensively by means of elemental analysis, fourier‐transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), Raman spectra, intrinsic viscosity, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The intrinsic viscosities of the prepared polyamides except nylon 3 11 are 0.70 to 0.87 dl g−1. The melting temperatures of the odd‐odd nylons range from 182 to 209 °C. In addition, the thermal mechanical properties of nylons 5 11, 7 11, 9 11 and 11 11 were analyzed using dynamic mechanical analysis (DMA). Nylon 3 11 could not undergo DMA due to its low molecular weight. The glass transition temperatures obtained from DMA are in the range 22–39 °C. Copyright © 2004 Society of Chemical Industry
Why biphenyl configuration still matters
Authors: Kahr Bart , Kaminsky Werner , Claborn Kacey 
Published: July 2004

AbstractMore than 40 years ago, Kurt Mislow synthesized restrained biphenyl derivatives, classically resolved them and correlated their absolute configuration with the sign of the Cotton effect. We have encountered biphenyl dyes in mixed crystals and crystalline tissues that were presumably resolved by interaction with chiral crystal facets or by adsorption to biopolymers. Understanding association mechanisms required that we likewise determine the absolute configuration, but inside organized media which traditionally do not reveal optical rotation or circular dichroism because of the dominance of linear anisotropies. We therefore recently invented the first circular extinction imaging microscope that can detect circular dichroism in low‐symmetry media, and also a new effect in crystal optics that we call anomalous circular extinction. Here, we show what information can be obtained from dyed, organized substances containing biphenyl derivatives by exploiting this new tool. Copyright © 2004 John Wiley & Sons, Ltd.
Time‐resolved IR studies of α‐lactones
Authors: Showalter Brett M. , Toscano John P. 
Published: July 2004

AbstractA series of α‐lactones were generated from the reaction of phenylchlorocarbene, 4‐nitrophenylchlorocarbene, diphenylcarbene, bis(4‐nitrophenyl)carbene and bis(4‐methoxyphenyl)carbene with carbon dioxide and examined by nanosecond time‐resolved infrared (TRIR) spectroscopy. Estimated second‐order rate constants for the reaction of these carbenes with carbon dioxide indicate that more nucleophilic carbenes react at faster rates, in agreement with previous low‐temperature matrix experiments. Spectral TRIR data confirms that the structure of α‐lactones is dependent both on substituents at the α‐carbon and on solvent polarity, with electron‐donating substituents and polar solvents favoring a zwitterionic ring‐opened structure as opposed to the three‐membered ring oxiranone form. B3LYP calculations using self‐consistent reaction field (SCRF) methods also provide support for these experimental investigations. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and spectroscopic characterization of the first chiral molecular ‘hamburger’
Authors: Consiglio Giuseppe A. , Failla Salvatore , Finocchiaro Paolo 
Published: July 2004

AbstractThe incorporation of the common tetrasubstituted benzene ring II between two rigid bisphosphonate spirobiindane units gives rise to two diastereoisomers macrobicyclophanes VA and VB in high yield. The structures of these two diastereomers were assigned by 1‐D and 2‐D NMR. Both products shown a structure were the benzene ring is sandwiched between the cyclic frames to form a chiral molecular ‘hamburger’. Copyright © 2004 John Wiley & Sons, Ltd.
Structure, polymorphism and thermal properties of phenyliminoisoindolines
Authors: Zhang Zhi‐Qin , Uth Samnang , Sandman Daniel J. , Foxman Bruce M. 
Published: July 2004

AbstractThe crystal and molecular structures of (a) 1‐imino‐3‐phenyliminoisoindoline (2), (b) two polymorphs (3Mono and 3Tric) and a hexane solvate (3Hex) of 1,3‐bis(phenylimino)isoindoline (3) and (c) 3‐phenyliminoisoindolinone (4) were determined via single‐crystal x‐ray diffraction. The two polymorphs and solvate of 3 were all obtained by crystallization from hexane. In the solid state, 2 is found as the anti isomer of the amino tautomer, and all forms of 3 exist as either the syn,anti or anti,anti isomers of the diimino tautomer. The 3Tric and 3Mono polymorphs represent a rare example in which the phenomena of conformational polymorphism and conformational isomorphism occur for the same substance. Compound 4 crystallizes as the anti isomer of the keto form. Differential scanning calorimetry and thermogravimetric analysis were performed to characterize the thermal properties of samples of 2–4. X‐ray powder diffraction studies on 2, 3 and 4 reveal that, whereas specimens of 2 are a single phase, none of the samples of 3 and 4 crystallize as single phases under the conditions of the experiments. Copyright © 2004 John Wiley & Sons, Ltd.
Kinetic analysis of a reactive model enediyne
Authors: Semmelhack M. F. , Sarpong R. 
Published: July 2004

AbstractA model framework related to the calcheamicin family of enediyne toxins was evaluated in its reactivity toward cycloaromatization through the arene 1,4‐diyl intermediates and hydrogen atom abstractions. The keto version 9 is relatively unreactive, with t1/2 = 1.5 h at 60°C. The product from hydride reduction of the ketone, alcohol 13b, is much more reactive, with t1/2=50 min at 0°C. In both cases, the rate of rearrangement is independent of the hydrogen atom donor, consistent with a rate‐determining first step (cyclization). Copyright © 2004 John Wiley & Sons, Ltd.
Cation–π complexes of a bowl‐shaped polycyclic aromatic hydrocarbon
Authors: Ansems Ronald B. M. , Scott Lawrence T. 
Published: July 2004

AbstractCircumtrindene (1), a C36H12 geodesic polyarene that represents 60% of fullerene‐C60, forms cation–π complexes with both silver ion (1·Ag+) and tetramethylammonium ion [(Me)4N+·1] in chloroform solution at room temperature (Ka>20 M−1 for both cations). Preferential binding in the concave pocket of 1 is predicted by DFT calculations for both cations; however, this stereochemical assignment has not yet been confirmed experimentally. Copyright © 2004 John Wiley & Sons, Ltd.
Metallo‐supramolecular block copolymer micelles: Improved preparation and characterization
Authors: Mayer Gottfried , Vogel Vitali , Lohmeijer Bas G. G. , Gohy Jean‐François , Van Den Broek Jacomina A. , Haase Winfried , Schubert Ulrich S. , Schubert Dieter 
Published: July 2004

AbstractMicelles prepared from amphiphilic block copolymers in which a poly(styrene) segment is connected to a poly(ethylene oxide) block via abis‐(2,2′:6′,2″‐terpyridine‐ruthenium) complex have been intensely studied. In most cases, the micelle populations were found to be strongly heterogeneous in size because of massive micelle/micelle aggregation. In the study reported in this article we tried to improve the homogeneity of the micelle population. The variant preparation procedure developed, which is described here, was used to prepare two “protomer”‐type micelles: PS20‐[Ru]‐PEO70and PS20‐[Ru]‐PEO375. The dropwise addition of water to a solution of the compounds in dimethylformamide was replaced by the controlled addition of water by a syringe pump. The resulting micelles were characterized by sedimentation velocity and sedimentation equilibrium analyses in an analytical ultracentrifuge and by transmission electron microscopy of negatively stained samples. Sedimentation analysis showed virtually unimodal size distributions, in contrast to the findings on micelles prepared previously. PS20‐[Ru]‐PEO70micelles were found to have an average molar mass of 318,000 g/mol (corresponding to 53 protomers per micelle, which is distinctly less than after micelle preparation by the standard method) and an average hydrodynamic diameter (dh) of 18 nm. For PS20‐[Ru]‐PEO375micelles, the corresponding values wereM= 603,000 g/mol (31 protomers per micelle) anddh= 34 nm. The latter particles were found to be identical to the “equilibrium” micelles prepared in pure water. Both micelle types had a very narrow molar mass distribution but a much broader distribution ofsvalues and thus of hydrodynamic diameters. This indicates a conformational heterogeneity that is stable on the time scale of sedimentation velocity analysis. The findings from electron microscopy were in disagreement with those from the sedimentation analysis both in average micelle diameter and in the width of the distributions, apparently because of imperfections in the staining procedure. The preparation procedure described also may be useful in micelle formation from other types of protomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4458–4465, 2004
Influence of ortho‐substituents on the synthesis and properties of poly(phenylacetylene)s
Authors: Mayershofer Martin G. , Wagner Martin , Anders Udo , Nuyken Oskar 
Published: July 2004

AbstractThe phenylacetylene derivatives (4‐decyloxyphenyl)acetylene (M1), (4‐decyloxy‐2‐methylphenyl)acetylene (M2), and (4‐decyloxy‐2,6‐dimethylphenyl)acetylene (M3) were polymerized by the well‐defined Schrock‐type initiator Mo[N‐2,6‐i‐Pr2C6H3)(CHCMe2Ph)[OCMe(CF3)2]2 (I1) and by the ill‐defined quaternary system MoOCl4–n‐Bu4Sn–EtOH–quinuclidine (1:1:2:1) (I2). Comparison of the compatibility of the initiators with the different monomers revealed a correlation of the size of the ortho‐substituents and the polymerizability of the monomers. M1 and M2 readily polymerized employing I1, but conversion of the sterically demanding monomer M3 remained incomplete. However, the use of I2 led to high monomer conversions and polymer yields only in case of M2 and M3. The steric bulkiness of the ortho‐substituents also decisively affected the maximum effective conjugation length (Neff) of the polymers and hence their absorption maximum (λmax) as well as their solution stability as shown by UV–vis and GPC studies, respectively. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4466–4477, 2004
Structures and properties of (H2GaN3)n (n = 1–4) clusters: A DFT study
Authors: Xia Qi Ying , Xiao He Ming , Ju Xue Hai , Gong Xue Dong 
Published: July 2004

AbstractComputations on the systems of (H2GaN3)n (n = 1–4) are performed using the density functional theory (DFT)/B3LYP method with different basis sets. (H2GaN3)2 possessing D2h symmetry is found to exhibit the planar Ga2N2 ring structure. (H2GaN3)3 involving a six‐membered Ga3N3 ring is found to exhibit two minima with very similar binding energies (ca. −235 ∼ −231 kJ · mol−1). One minimum is the newly found boat‐like conformation possessing Cs symmetry. Another minimum possessing C3v symmetry is the chair‐like conformation. (H2GaN3)4 occurs in several structures with Ga4N4 eight‐membered ring structures that correspond to minima with slight energy differences among them. The structural changes of the clusters are large compared with the monomer. Frequency calculations are carried out on each optimized structure, and their infrared (IR) spectra are discussed. Thermodynamic properties demonstrate that the systems of H2GaN3 occur at dimer–trimer–tetramer equilibrium, and the trimer is the main component. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Tests of perturbative DFT total energy estimates implemented in a Gaussian basis
Authors: Zhu Wuming , Trickey S. B. 
Published: July 2004

AbstractWe derive and test an approximate expression for the Kohn–Sham eigenfunctions and total energy associated with a given exchange‐correlation functional. The expression is closely related to the approximation given by Benoit et al. (Phys Rev Lett 2001, 87, 226401) but differs by removing an overly stringent orthogonality constraint. Tests on the Li, F, Ne, and Cr atoms done in Gaussian basis sets suggest that the approach is promising, particularly as an alternative to conventional self‐consistent field or to the Harris scheme (Phys Rev B 1985, 31, 1770). © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Simultaneous selected reaction monitoring, MS/MS and MS3 quantitation for the analysis of pharmaceutical compounds in human plasma using chip‐based infusion
Authors: Leuthold Luc Alexis , Grivet Chantal , Allen Mark , Baumert Mark , Hopfgartner Gérard 
Published: July 2004

AbstractAn assay method with mass spectrometric detection was developed for the quantitative analysis of a pharmaceutical compound and its major metabolite in human plasma using chip‐based infusion. Liquid‐liquid extraction sample preparation was found to be essential to minimize matrix suppression and to achieve a limit of quantitation (LOQ) of 2.5 ng/mL using a 100 μL plasma aliquot. The potential for simultaneous quantitation in selected reaction monitoring (SRM), tandem mass spectrometry (MS/MS) (enhanced product ion), and MS3 was investigated and found to be very beneficial in improving assay selectivity. A novel concept for monitoring quantitative assay performance using a SRM/MS3 ratio is proposed. Copyright © 2004 John Wiley & Sons, Ltd.
Black knight: An autonomous vehicle for competition
Authors: Gonzalez Fernando G. , Andres Richard , Deal David , Goergen Frank , Rhodes Matt , Roberts Tim , Stein Gary , Wilson Josh , Wong Sarah 
Published: July 2004

AbstractBlack Knight, the University of Central Florida's vehicle in the 11th Intelligent Ground Vehicle Competition (IGVC) competed in 2003. Completing in 5th place in the navigational challenge and 10th in the autonomous challenge in its first competition has proven our vehicle to be a strong competitor in this competition. The vehicle has many interesting features that allow it to achieve its success. The vehicle's 300 lb. capacity allows for two onboard full‐sized computers and two 12 V marine batteries that power the computers for up to 2 h. The vision system is not a simple reactive system but rather it classifies its view into objects and builds a map of the territory as it learns of its features while traveling. Two transformations and the location data from the GPS and other sensors are used to associate the locations in the image to locations in the map. The operations of the vehicle are modeled after the typical operations of a ship. We have programs that perform the functions of the captain, the helm, the navigator, and the engineer. In addition we have a program performing sensor data fusion from the GPS, compass, and wheel encoder data. The navigation uses an adapted two‐dimensional approximate cell decomposition method that satisfies the nonholononic constraints of our vehicle and allows it to find the shortest path to the goal while avoiding all obstacles. © 2004 Wiley Periodicals, Inc.
Vasilius: The design of an autonomous ground robotic vehicle
Authors: Snider Jarrod M. , Snider Amy E. , Riggins Robert N. 
Published: July 2004

AbstractThis paper presents the design and provides a partial analysis of the performance of an autonomous ground robotic vehicle called Vasilius. Applications for Vasilius include autonomous navigation on a somewhat marked path with obstacles, leader following, and waypoint navigation. The paper focuses on three aspects of Vasilius: the design, the performance, and a technique for filtering, mapping, and learning. The design of Vasilius embodies a novel idea of modeling an autonomous vehicle after human senses and the human decision‐making process. For instance, Vasilius integrates information from seven types of independent sensors, and categorizes them into either short‐range reaction sensors and/or long‐range planning sensors, analogous to what the human brain does. The paper also analyzes the performance of Vasilius, relating theoretical predictions to actual behavior. Some of these analyses, especially for the filtering, mapping, and learning, are still in progress. Performance measures that have been measured include speed, ramp climbing, turn reaction time, battery life, stop reaction time, object detection, and waypoint accuracy. Finally, the paper discusses Vasilius' use of a new approach to filtering, mapping, and learning to enhance its performance. © 2004 Wiley Periodicals, Inc.
Perceptions of child support and sexual activity of adolescent males
Authors: Huang Chien‐Chung , Han Wen‐Jui 
Published: July 2004

AbstractUsing the 1995 new cohort of the National Survey of Adolescent Males, this paper examines the association between perceptions of child support and adolescent males’ sexual activity. The results indicate that adolescent males who expect the chance of being required to pay child support is high if one becomes a non‐resident father or who has a family member who paid child support before are more likely to have the same female sexual partner and less likely to have had two or more female partners. Additionally, expectations of being required to pay child support and history of a family member paying child support are positively associated with contraceptive use, especially for Black adolescents.
Retrospective and prospective cognitions in adolescents: anxiety, depression, and positive and negative affect
Authors: Miles Helen , MacLeod Andrew K. , Pote Helen 
Published: July 2004

AbstractResearch with anxious and depressed adults has suggested that anxiety is related to an increased anticipation of both negative memories and negative expectancies whereas depression is related to a reduction in positive memories and expectancies. The present study examined whether anxiety and depression in 123 school‐aged adolescents would show the same pattern. Small groups completed a memory and future thinking task in which they were asked to generate future and past, positive and negative events. Adolescents with higher levels of depression and those with higher levels of anxiety reported significantly more negative events relative to controls, but neither group generated fewer positive events. The results provide support for the involvement of cognitions in mood disturbance although do not support the idea that these cognitions are different in anxiety and depression.