bluuebunny/crossref_metadata_2025 huggingface dataset:
Space‐time clustering of childhood cancer in great Britain: A national study, 1969–1993
Authors: McNally Richard J.Q. , Alexander Freda E. , Bithell John F.
Published: December 2005

Previous studies have provided evidence that infections may play a part in the aetiology of certain childhood cancers. The finding of space‐time clustering indicates the presence of an environmental component to aetiology and is especially supportive of a role for infections. Space‐time clustering occurs when excess numbers of cases of a disease are observed within small geographical locations at limited periods of time and this cannot be explained in terms of general excesses in those locations or at those times. To investigate whether infections may be involved in the aetiology of childhood cancer, we have analysed for space‐time clustering using a large set of national population‐based data from Great Britain for the period 1969–1993. Data were examined by a second‐order procedure based on K‐functions, with fixed thresholds of closeness in space (0.5–7.5 km) and closeness in time (0.1–1.5 years). Locations were addresses at diagnosis. Tests were repeated, replacing geographical distances with distances to the 19th–33rd nearest neighbours and this provided the primary result for each analysis. There were a total of 32,295 cases of childhood cancer. The analyses showed statistically significant evidence of space‐time clustering for acute lymphoblastic leukaemia over the whole age range (p = 0.04), but especially for ages 1–4 years (p = 0.03). There was less statistically significant evidence for total leukaemia (p = 0.048). Significant space‐time clustering was also evident for soft tissue sarcomas (p = 0.03) and osteosarcomas (p = 0.02). Results support other evidence suggesting a role for infections in the aetiology of these particular diagnostic groups. © 2005 Wiley‐Liss, Inc.
The Salzburg concept of intraoperative radiotherapy for breast cancer: Results and considerations
Authors: Reitsamer Roland , Sedlmayer Felix , Kopp Michael , Kametriser Gerhard , Menzel Christian , Deutschmann Heinz , Nairz Olaf , Hitzl Wolfgang , Peintinger Florentia
Published: December 2005

Aim of this study is to show that ipsilateral breast tumor recurrence (IBTR) after breast conserving surgery can be reduced by proper surgery and modern radiotherapy techniques. Three hundred and seventy eight women with stage I or II breast cancer had breast conserving surgery and received 51–56.1 Gy of postoperative radiation to the whole breast in 1.7 Gy fractions, but patients received different boost strategies. Group 1 (n = 188) received electron boost radiation of 12 Gy subsequent to the irradiation to the whole breast, group 2 (n = 190) received intraoperative electron boost radiation of 9 Gy directly to the tumor bed, followed by whole breast irradiation. After a median follow up period of 81.0 months in group 1 and a median follow up period of 51.1 months in group 2, 12 IBTRs (6.4%) could be observed in group 1 and no IBTR could be observed in group 2 (0.0%). The 5‐year actuarial rates of IBTR were 4.3% (95% CI, 1.9–8.3%) and 0.0% (95% CI, 0.0–1.9%), respectively (p = 0.0018). The 5‐year actuarial rates of distant recurrence were 8.6% (95% CI, 4.9–13.5%) and 4.2% (95% CI, 1.8–8.2%), respectively (p = 0.08). The 5 year disease‐free survival rates were 90.9% (95% CI, 85.8–94.7%) in group 1 and 95.8% (95% CI, 91.8–98.2%) in group 2 (p = 0.064). Immediate IORT‐boost and whole breast irradiation yields excellent local control at 5 years, and was associated with a statistically significant decreased rate of IBTR compared with a similar cohort of patients treated with whole breast irradiation and conventional electron boost. © 2005 Wiley‐Liss, Inc.
A search algorithm for fixed‐composition protein design
Authors: Hom Geoffrey K. , Mayo Stephen L.
Published: December 2005

We present a computational protein design algorithm for finding low‐energy sequences of fixed amino acid composition. The search algorithms used in protein design typically do not restrict amino acid composition. However, the random energy model of Shakhnovich suggests that the use of fixed‐composition sequences may circumvent defects in the modeling of the denatured state. Our algorithm, FC_FASTER, links fixed‐composition versions of Monte Carlo and the FASTER algorithm. As proof of principle, FC_FASTER was tested on an experimentally validated, full‐sequence design of the β1 domain of protein G. For the wild‐type composition, FC_FASTER found a lower energy sequence than the experimentally validated sequence. Also, for a different composition, FC_FASTER found the hypothetical lowest‐energy sequence in 14 out of 32 trials. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 375–378, 2006
Continuous medium theory for nonequilibrium solvation: IV. Solvent reorganization energy of electron transfer based on conductor‐like screening model
Authors: Fu Ke‐Xiang , Zhu Quan , Li Xiang‐Yuan , Gong Zhen , Ma Jian‐Yi , He Rong‐Xing
Published: December 2005

In this work the authors present some evidences of defects in the popular continuous medium theories for nonequilibrium solvation. Particular attention has been paid to the incorrect reversible work approach. After convincing reasoning, the nonequilibrium free energy has been formulated to an expression different from the traditional ones. In a series of recent works by the authors, new formulations and some analytical application models for ultrafast processes were developed. Here, the authors extend the new theory to the cases of discrete bound charge distributions and present the correct form of the nonequilibrium solvation energy in such cases. A numerical solution method is applied to the evaluation of solvent reorganization energy of electron transfer. The test calculation for biphenyl–cyclohexane–naphthalene anion system achieves excellent agreement with the experimental fitting. The central importance presented in this work is the very simple and a consistent form of nonequilibrium free energy for both continuous and discrete charge distributions, based on which the new models can be established. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 368–374, 2006
Postembryonic development of Tanystylum bealensis (Pycnogonida, Ammotheidae) from Barkley Sound, British Columbia, Canada
Authors: Gillespie J.M. , Bain B.A.
Published: December 2005

All developmental stages of Tanystylum bealensis are described. This is the first complete developmental series of a pycnogonid species collected from a natural, rather than a laboratory‐reared population. Development proceeds through a series of nine instars from egg to adult, with major defining characteristics of the instars being the addition of walking legs, loss of chelifores, and modification of larval appendages into adult palps and ovigers. All stages are free‐living on the hydroid Plumularia setacea, except for the first instar (protonymphon), which remains on the ovigers of the adult male for a short time after hatching. Development in T. bealensis is compared to development in both the closely related species T. orbiculare and to the more distantly related Achelia alaskensis. J. Morphol. © 2005 Wiley‐Liss, Inc.
Sizing the Jurassic theropod dinosaur Allosaurus: Assessing growth strategy and evolution of ontogenetic scaling of limbs
Authors: Bybee Paul J. , Lee Andrew H. , Lamm Ellen‐Thérèse
Published: December 2005

Allosaurus is one of the most common Mesozoic theropod dinosaurs. We present a histological analysis to assess its growth strategy and ontogenetic limb bone scaling. Based on an ontogenetic series of humeral, ulnar, femoral, and tibial sections of fibrolamellar bone, we estimate the ages of the largest individuals in the sample to be between 13–19 years. Growth curve reconstruction suggests that maximum growth occurred at 15 years, when body mass increased 148 kg/year. Based on larger bones of Allosaurus, we estimate an upper age limit of between 22–28 years of age, which is similar to preliminary data for other large theropods. Both Model I and Model II regression analyses suggest that relative to the length of the femur, the lengths of the humerus, ulna, and tibia increase in length more slowly than isometry predicts. That pattern of limb scaling in Allosaurus is similar to those in other large theropods such as the tyrannosaurids. Phylogenetic optimization suggests that large theropods independently evolved reduced humeral, ulnar, and tibial lengths by a phyletic reduction in longitudinal growth relative to the femur. J. Morphol. © 2005 Wiley‐Liss, Inc.
Experimental evolution and phenotypic plasticity of hindlimb bones in high‐activity house mice
Authors: Kelly Scott A. , Czech Polly P. , Wight Jeffrey T. , Blank Katie M. , Garland Theodore
Published: December 2005

Studies of rodents have shown that both forced and voluntary chronic exercise cause increased hindlimb bone diameter, mass, and strength. Among species of mammals, “cursoriality” is generally associated with longer limbs as well as relative lengthening of distal limb segments, resulting in an increased metatarsal/femur (MT/F) ratio. Indeed, we show that phylogenetic analyses of previously published data indicate a positive correlation between body mass‐corrected home range area and both hindlimb length and MT/F in a sample of 19 species of Carnivora, although only the former is statistically significant in a multiple regression. Therefore, we used an experimental evolution approach to test for possible adaptive changes (in response to selective breeding and/or chronic exercise) in hindlimb bones of four replicate lines of house mice bred for high voluntary wheel running (S lines) for 21 generations and in four nonselected control (C) lines. We examined femur, tibiafibula, and longest metatarsal of males housed either with or without wheel access for 2 months beginning at 25–28 days of age. As expected from previous studies, mice from S lines ran more than C (primarily because the former ran faster) and were smaller in body size (both mass and length). Wheel access reduced body mass (but not length) of both S and C mice. Analysis of covariance (ANCOVA) revealed that body mass was a statistically significant predictor of all bone measures except MT/F ratio; therefore, all results reported are from ANCOVAs. Bone lengths were not significantly affected by either linetype (S vs. C) or wheel access. However, with body mass as a covariate, S mice had significantly thicker femora and tibiafibulae, and wheel access also significantly increased diameters. Mice from S lines also had heavier feet than C, and wheel access increased both foot and tibiafibula mass. Thus, the directions of evolutionary and phenotypic adaptation are generally consistent. Additionally, S‐line individuals with the mini‐muscle phenotype (homozygous for a Mendelian recessive allele that halves hindlimb muscle mass [Garland et al., 2002, Evolution 56:1267–1275]) exhibited significantly longer and thinner femora and tibiafibulae, with no difference in bone masses. Two results were considered surprising. First, no differences were found in the MT/F ratio (the classic indicator of cursoriality). Second, we did not find a significant interaction between linetype and wheel access for any trait, despite the higher running rate of S mice. J. Morphol. © 2005 Wiley‐Liss, Inc.
Ultrastructural investigation of a salivary gland in a centipede: Structure and origin of the maxilla I‐gland of Scutigera coleoptrata (Chilopoda, Notostigmophora)
Authors: Hilken Gero , Rosenberg Jörg
Published: December 2005

The maxilla I‐gland of Scutigera coleoptrata was investigated using light and electron microscopy methods. This is the first ultrastructural investigation of a salivary gland in Chilopoda. The paired gland opens via the hypopharynx into the foregut and extends up to the third trunk segment. The gland is of irregular shape and consists of numerous acini consisting of several gland units. The secretion is released into an arborescent duct system. Each acinus consists of multiple of glandular units. The units are composed of three cell types: secretory cells, a single intermediary cell, and canal cells. The pear‐shaped secretory cell is invaginated distally, forming an extracellular reservoir lined with microvilli, into which the secretion is released. The intermediary cell forms a conducting canal and connects the secretory cell with the canal cell. Proximally, the intermediary cell bears microvilli, whereas the distal part is covered with a distinct cuticle. The cuticle is a continuation of the cuticle of the canal cells. This investigation shows that the structure of the glandular units of the salivary maxilla I‐gland is comparable to that of the glandular units of epidermal glands. Thus, it is likely that in Chilopoda salivary glands and epidermal glands share the same ground pattern. It is likely that in compound acinar glands a multiplication of secretory and duct cells has taken place, whereas the number of intermediary cells remains constant. The increase in the number of salivary acini leads to a shifting of the secretory elements away from the epidermis, deep into the head. Comparative investigations of the different head glands provide important characters for the reconstruction of myriapod phylogeny and the relationships of Myriapoda and Hexapoda. J. Morphol. © 2005 Wiley‐Liss, Inc.
Multilayered Assembly of Cellulose Derivatives as Primer for Surface Modification by Polymerization
Authors: Woo C. K. , Schiewe B. , Wegner G.
Published: December 2005

Summary: Rod‐like cellulose polymers, with flexible isopentyl side chains, form supramolecular constructs by the Langmuir‐Blodgett (LB) technique. These have been employed to model an ultrathin multilayered primer for surface modification by polymerization. Multilayers of this polymer were doped with a solution of a photosensitizer and then exposed to methyl methacrylate, (MMA) in either the vapor or liquid phase. Polymerization of the monomer swollen construct was induced photochemically. FT‐IR spectra reveal that photoinitiation in presence of the photosensitizer or irradiation in the far UV region induces photografting by hydrogen abstraction from the constituents of the layered assembly. Employing a combination of photoinitiators (benzophenone and 4,4′‐bis(diethylamino)‐benzophenone) and irradiation of the construct that was saturated by monomer from the gas phase in the near UV region caused the formation of a semi‐interpenetrating polymer network. Linear polymer chains of PMMA grow and entangle inside the layered assembly of the cellulose derivative. The resulting composite consists of two polymers, isopentylcellulose and poly(methyl methacrylate) demonstrating a possibility to produce a homogeneous layered composite film at nanoscopic scale as revealed by the X‐ray reflectometry. Surface photopolymerization was also achieved in the liquid phase where the monomer and photoinitiator solution was in direct contact with the layered assembly.

Schematic picture of the composite films consisting of multilayered CIPC and PMMA incorporated via vapor phase photopolymerization. The scale of the CIPC hairy‐rods and periodic spacing is only schematically represented.

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Schematic picture of the composite films consisting of multilayered CIPC and PMMA incorporated via vapor phase photopolymerization. The scale of the CIPC hairy‐rods and periodic spacing is only schematically represented.
Formation of Novel Layered Nanostructures from Lanthanide‐Complexes by Secondary Interactions with Ligating Monomers in Miniemulsion Droplets
Authors: Ramírez Liliana Patricia , Antonietti Markus , Landfester Katharina
Published: December 2005

Summary: The addition of neutral, inert inner shell lanthanide complexes such as Gd(III)‐(tmhd)3, Eu(III)‐(fod)3, or Ho(III)‐thmd3, broadly available as NMR shift reagents, towards ester‐containing monomers such as butyl acrylate and subsequent polymerization in miniemulsion droplets leads to the spontaneous formation of highly organized layered nanocomposite particles, as revealed by electron microscopy and small angle X‐ray scattering. The nanocomposite comprises a lanthanide complex phase and a polymer phase with a lamellar repeat period of about 3.5 nm, rather independent of the system composition.

TEM micrograph of a PGd‐3 nanocomposite and corresponding chemical structure of the complex Gd(tmhd)3.

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TEM micrograph of a PGd‐3 nanocomposite and corresponding chemical structure of the complex Gd(tmhd)3.
Carbon Nanotube‐Adsorbed Electrospun Nanofibrous Membranes of Nylon 6
Authors: Kim Hyun Suk , Jin Hyoung‐Joon , Myung Seung Jun , Kang Minsung , Chin In‐Joo
Published: December 2005

Summary: A simple and mass‐producible method was developed to densely assemble multiwalled carbon nanotubes (MWNTs) onto electrospun nylon 6 nanofibrous membranes. The process consists of dispersing the acid‐treated MWNTs in surfactant solutions or organic solvents, and dipping the nanofibrous membranes in the resulting dispersion for only 60 seconds, followed by the extraction of the surfactants in pure water and drying. The conductivity of the MWNT‐adsorbed nanofibrous membranes ranges from 2.2 × 10−2 to 1.5 × 10−1 S · cm−1, as determined by the four probe method, which implies that the MWNTs are adsorbed uniformly and densely along the nanofibrous membranes. Furthermore, the results suggest that there is a strong interaction between the acid‐treated MWNTs and nylon 6. We also investigate the amount of MWNTs present in the membranes using thermogravimetric analysis.

SEM images of the non‐woven fibrous nylon 6 membranes after dip‐coating in a dispersion of the MWNTs in surfactant‐containing water.

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SEM images of the non‐woven fibrous nylon 6 membranes after dip‐coating in a dispersion of the MWNTs in surfactant‐containing water.
Microwave‐Assisted Free Radical Polymerizations and Copolymerizations of Styrene and Methyl Methacrylate
Authors: Stange Heiner , Ishaque Michael , Niessner Norbert , Pepers Michel , Greiner Andreas
Published: December 2005

Summary: Radical homopolymerizations and copolymerizations of styrene were performed in toluene and N,N‐dimethylformamide (DMF) as solvents using different initiators with and without microwave irradiation. Only the homopolymerization of styrene under microwave irradiation in DMF with DtBP showed significantly enhanced styrene conversion whereas other initiators resulted in no or only slight increase of styrene conversion under microwave irradiation. In any case, DMF was required to gain in styrene conversion under microwave irradiation. Significantly higher monomer conversions were observed under otherwise comparable conditions in the copolymerization of styrene and methyl methacrylate (MMA) in DMF. Microwave‐induced selectivity of monomers was not observed in copolymerizations.

Yield of styrene polymerizations under varying reaction conditions initiated by DtBP.

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Yield of styrene polymerizations under varying reaction conditions initiated by DtBP.
Polymeric Nanocomposites of Polyurethane Block Copolymers and Functionalized Multi‐Walled Carbon Nanotubes as Crosslinkers
Authors: Jung Yong Chae , Sahoo Nanda Gopal , Cho Jae Whan
Published: December 2005

Summary: We report on a new route to synthesize polymeric carbon nanotube‐polyurethane (PU) nanocomposites. Multi‐walled carbon nanotubes (MWNTs) functionalized by chemical modification were incorporated as a crosslinker in prepolymer, which was prepared from a reaction of 4,4′‐methylene bis(phenylisocyanate) and poly(ε‐caprolactone)diol. The reinforcing effect of carbon nanotubes in crosslinked MWNT‐PU nanocomposites was more pronounced as compared to that in conventional MWNT‐PU nanocomposites. The optimum content of chemically modified MWNTs for crosslinking with polyurethane was determined to be approximately 4 wt.‐% in our samples, based on observation of a NCO peak in FT‐IR spectroscopy. MWNT‐crosslinked polyurethane containing 4 wt.‐% modified MWNTs showed the highest modulus and tensile strength among the composites and pure PU. The presence of functionalized MWNTs in the polymeric nanocomposite yielded enhancement in the thermal stability due to crosslinking of the MWNTs with PU.

Possible configuration for MWNT‐PU nanocomposite molecules and FT‐IR spectra of samples obtained during reaction of prepolymer with functionalized MWNTs (second step).

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Possible configuration for MWNT‐PU nanocomposite molecules and FT‐IR spectra of samples obtained during reaction of prepolymer with functionalized MWNTs (second step).
Reversible Addition‐Fragmentation Transfer Polymerization in the Presence of MMT Immobilized Amphoteric RAFT Agent
Authors: Zhang Bao‐Qing , Pan Cai‐Yuan , Hong Chun‐Yan , Luan Bin , Shi Peng‐Jie
Published: December 2005

Summary: A novel reversible addition‐fragmentation transfer (RAFT) agent, 10‐carboxylic acid‐10‐dithiobenzoate‐decyltrimethylammonium bromide (CDDA), was synthesized and intercalated into montmorillonite (MMT). Successively, the CDDA‐intercalated MMT was used as RAFT agent in the in situ RAFT polymerization for preparation of the polystyrene/MMT nanocomposites. After separation of MMT, the polymers obtained have predictable molecular weight and narrow polydispersity. XRD spectra and TEM images of the nanocomposites demonstrated exfoliated structure. Thermal stability of the composites has been noticeably improved.

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Force Spectroscopy of Individual Stimulus‐Responsive Poly(ferrocenyldimethylsilane) Chains: Towards a Redox‐Driven Macromolecular Motor
Authors: Zou Shan , Hempenius Mark A. , Schönherr Holger , Vancso G. Julius
Published: December 2005

Summary: Progress in the development of a redox‐driven macromolecular motor and the characterization of its redox‐mechanical cycle using electrochemical AFM‐based single‐molecule force spectroscopy (SMFS) is described. The elasticities of individual neutral and oxidized poly(ferrocenyldimethylsilane) (PFS) macromolecules were reversibly controlled in situ by adjusting the potential in electrochemical SMFS experiments. For the operating cycle of one individual PFS‐based molecular motor, an output of 3.4 × 10−19 J and an efficiency of 5% have been estimated.

Force‐extension curves of a single‐molecule motor.

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Force‐extension curves of a single‐molecule motor.
Enforcing Effect of Double‐Fullerene End‐Capped Poly(ethylene oxide) on Mechanical Properties of Poly(L‐lactic acid)
Authors: Kai Weihua , Zhao Li , Zhu Bo , Inoue Yoshio
Published: December 2005

Summary: The fracture strain for the composite of poly(L‐lactic acid) (PLLA) and double‐fullerene end‐capped poly(ethylene oxide) (FPEOF) was observed about 100 times of PLLA with a high modulus for room‐temperature aged samples. The aggregates of fullerene of FPEOF ends give rise to the formation of physical network of poly(ethylene oxide), which forms a pseudo‐semi‐interpenetrating network with PLLA and renders the astonishing enforcing effect on the PLLA.

Strain‐stress curves of PLLA and PLLA/FPEO20F6 composite.

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Strain‐stress curves of PLLA and PLLA/FPEO20F6 composite.
Dispersion Polymerization of Methyl Methacrylate in Supercritical Carbon Dioxide in the Presence of Random Copolymers
Authors: Hwang Ha Soo , Gal Yeong‐Soon , Johnston Keith P. , Lim Kwon Taek
Published: December 2005

Summary: Statistical random copolymers of 1H,1H‐perfluorooctyl methacrylate and 2‐dimethylaminoethyl methacrylate, poly(FOMA‐co‐DMAEMA), effectively stabilized the dispersion polymerization of methyl methacrylate in supercritical carbon dioxide. Free‐flowing, micron‐sized spherical PMMA particles could be produced with poly(FOMA‐co‐DMAEMA) containing 34 w/w% FOMA.

SEM image of PMMA particles prepared with poly(FOMA‐co‐DMAEMA) (34:66).

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SEM image of PMMA particles prepared with poly(FOMA‐co‐DMAEMA) (34:66).
Dynamics of Hollow Nanofiber Formation During Solidification Subjected to Solvent Evaporation
Authors: Guenthner Andrew J. , Khombhongse Sureeporn , Liu Wenxia , Dayal Pratyush , Reneker Darrell H. , Kyu Thein
Published: December 2005

Summary: To mimic the emergence of gradient morphology in polymer nanofibers, a new theoretical approach has been developed in the context of Cahn‐Hilliard time evolution equation, alternatively known as time‐dependent Ginzburg‐Landau equation (Model B) involving concentration order parameter. The effects of solvent evaporation on the morphology evolution of the nanofibers have been demonstrated. The numerical simulation showed that the formation of skin layers is governed by the competition between solvent evaporation rate and mutual diffusion rate. That is to say the skin layers are formed in the nanotube whenever the rate of evaporation exceeds a critical value; otherwise, a solid fiber is formed. In hollow nanofibers, the layer can grow to a substantial fraction of the fiber diameter, allowing it to remain intact, albeit often in a collapsed form.

The cross‐sectional concentration profile of the emerging fiber.

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The cross‐sectional concentration profile of the emerging fiber.
Rate Optimization in Controlled Radical Emulsion Polymerization Using RAFT
Authors: Prescott Stuart W. , Ballard Mathew J. , Rizzardo Ezio , Gilbert Robert G.
Published: December 2005

Summary: Means of improving rates in RAFT‐mediated radical emulsion polymerizations are developed, by setting out strategies to minimize the inhibition and retardation that always are present in these systems. These effects arise from the RAFT‐induced exit of radicals, the desorption of the RAFT‐reinitiating radical from the particles, and the specificity of the reinitiating radical to the RAFT agent. Methods for reducing the inhibition period such as using a more hydrophobic reinitiating radical are predicted to show a significant improvement in the inhibition periods. The time‐dependent behavior of the RAFT adduct to the entering radical and the RAFT‐induced exit (loss) of radicals from particles are studied using a previously described Monte Carlo model of RAFT/emulsion particles. It is shown that an effective way of reducing the rate coefficient for the exit of radicals from the particles is to use a less active RAFT agent. Techniques for improving the rate of polymerization of RAFT/emulsion systems are suggested based upon the coherent understanding contained in these models: the use of an oligomeric adduct to the RAFT agent, a less water‐soluble RAFT re‐initiating group, and a less active RAFT agent.

Populations of the different types of particles (left axis) along with the concentration of the initial RAFT agent, DR (right axis), as a function of time.

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Populations of the different types of particles (left axis) along with the concentration of the initial RAFT agent, DR (right axis), as a function of time.
A Definition of Dynamically Accessible Volume for Thermal Systems
Authors: Molina‐Mateo José , Meseguer‐Dueñas José M. , Gómez‐Ribelles José L.
Published: December 2005

Summary:The glass transition and physical aging processes of a polymeric material have been simulated using the bond fluctuation model. Two potentials that represent intra‐ and inter‐molecular interactions have been employed. Simulations of different thermal histories that include cooling from equilibrium have been performed. The evolution of the system and the structure attained at low temperature are analyzed as a function of the assumed weight of inter‐ and intra‐molecular potentials in the total energy of the system. A new way of characterizing the free volume of the system and its evolution with the temperature or time is proposed. It is based on the concept of dynamically accessible volume but modified in the sense of considering the probability of an empty site to be accessed according to a Metropolis criterion. The results obtained show that the thermal redefinition of the dynamically accessible volume, TDAV, offers a better representation of the real mobility of the polymeric systems. The use of information on the structure of the system coming from the pair‐correlation function and the molecular mobility in the glassy state characterized by the time evolution of TDAV allows to reach the conclusion that a combination of inter‐ and intra‐molecular potentials produces the vitrification of the polymer system on cooling.

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Molecular Weight Distribution of Living Radical Polymers
Authors: Tobita Hidetaka
Published: December 2005

Summary: The molecular weight distribution formed in an ideal living radical polymerization is considered theoretically. It was found that the hypergeometric function that combines the most probable and the Poisson distribution represents a fundamental distribution of the living radical polymers. The number‐ and weight‐average molecular weights are derived for this fundamental distribution, together with those for polymerizations in a batch and in a continuous stirred tank reactor. These average molecular weight functions are obtained based on the arithmetic calculations without deriving the distribution functions. The effect of the monomer transfer reactions on the formed MWD is also considered. The present study clarifies the relationship between the reaction mechanism and the formed molecular weight distribution as well as the fundamental characteristics of living radical polymers.

Calculated number fraction distribution N(r) development with (dashed) and without (solid) the monomer transfer reactions.

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Calculated number fraction distribution N(r) development with (dashed) and without (solid) the monomer transfer reactions.
Molecular Weight Distribution of Living Radical Polymers
Authors: Tobita Hidetaka
Published: December 2005

Summary: A new Monte Carlo simulation method is proposed for the living radical polymerization on the basis of the random sampling technique. The stable free‐radical polymerization is used as a specific reaction mechanism. The illustrative calculations are conducted to investigate the effects of simultaneous use of two different types of radical initiators, with a large and a small decomposition rate constant. The addition of second initiator that decomposes slowly leads to a significant increase in the polymerization rate. The increased frequency of forming the dead and new growing polymer chains makes the molecular weight distribution (MWD) broader. On the other hand, however, there exists a weak but definite factor to reduce the polydispersity, which may compensate the broadening. On the basis of the simulation studies, one may find an excellent reaction condition to produce polymer with a higher productivity, having a larger MW, and with a narrow distribution. The effect of the monomer transfer reactions on the formed MWD is investigated to find that the transfer reactions must be accounted for when the designed number‐average chain length is larger than about 10% of 1/Cm, where Cm is the monomer transfer constant.

Calculated weight fraction distribution W(log r) with (C11) and without (C10) the second initiator.

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Calculated weight fraction distribution W(log r) with (C11) and without (C10) the second initiator.
Progress in the pursuit of therapeutic adenosine receptor antagonists
Authors: Moro Stefano , Gao Zhan‐Guo , Jacobson Kenneth A. , Spalluto Giampiero
Published: December 2005

Ever since the discovery of the hypotensive and bradycardiac effects of adenosine, adenosine receptors continue to represent promising drug targets. First, this is due to the fact that the receptors are expressed in a large variety of tissues. In particular, the actions of adenosine (or methylxanthine antagonists) in the central nervous system, in the circulation, on immune cells, and on other tissues can be beneficial in certain disorders. Second, there exists a large number of ligands, which have been generated by introducing several modifications in the structure of the lead compounds (adenosine and methylxanthine), some of them highly specific. Four adenosine receptor subtypes (A1, A2A, A2B, and A3) have been cloned and pharmacologically characterized, all of which are G protein‐coupled receptors. Adenosine receptors can be distinguished according to their preferred mechanism of signal transduction: A1 and A3 receptors interact with pertussis toxin‐sensitive G proteins of the Gi and Go family; the canonical signaling mechanism of the A2A and of the A2B receptors is stimulation of adenylyl cyclase via Gs proteins. In addition to the coupling to adenylyl cyclase, all four subtypes may positively couple to phospholipase C via different G protein subunits. The development of new ligands, in particular, potent and selective antagonists, for all subtypes of adenosine receptors has so far been directed by traditional medicinal chemistry. The availability of genetic information promises to facilitate understanding of the drug–receptor interaction leading to the rational design of a potentially therapeutically important class of drugs. Moreover, molecular modeling may further rationalize observed interactions between the receptors and their ligands. In this review, we will summarize the most relevant progress in developing new therapeutic adenosine receptor antagonists. © 2005 Wiley Periodicals, Inc.
Single‐mode yield in DFB laser diodes with reflecting facets
Authors: Ferreira Fernandes Carlos Alberto
Published: December 2005

Conventional DFB laser diodes present symmetric emission patterns, thus making these structures inadequate as single‐mode lasers. The simplest way of achieving single longitudinal‐mode operation is to make one or more facets as cleaved, rather than using AR coating. Single‐mode yield in asymmetric structures is calculated using matrix techniques. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 205–209, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21306
Broadband coplanar waveguide‐fed printed monopole antenna with strip‐sleeves
Authors: Coulibaly Yacouba , Denidni Tayeb A. , Talbi Larbi
Published: December 2005

In this paper, the design of a new broadband printed antenna for wireless applications is presented. The proposed antenna structure consists of a planar monopole fed by a coplanar waveguide (CPW) and four strip sleeves. With the integration of these parasitic elements, a wide bandwidth response is achieved. The antenna is designed at the operating frequency of 2.8 GHz, and a parametric study is also performed in order to optimize its operating bandwidth. To validate the design, an antenna prototype is fabricated and tested, and good agreement between the simulated and measured results is obtained. The experimental results show a bandwidth of 49.3%. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 209–212, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21307
A novel separable backward–central FDTD method
Authors: Yu Wenhua , Su Tao , Mittra Raj
Published: December 2005

In this paper, we present a novel separable backward–central FDTD (SBC‐FDTD) method in which the backward and central differences are used to discretize both time and spatial directive of the Maxwell's equations. For the type of problem in which the FDTD cell size in one direction is much smaller than those in the other directions, the time step in the proposed separable backward‐central FDTD technique can be chosen based on the largest cell size instead of the smallest one used in the conventional Yee's FDTD. Compared to the alternating‐direction implicit FDTD (ADI‐FDTD), although the proposed approach is not unconditionally stable, it allows us to explicitly solve electric and magnetic fields in one direction. Both the numerical experiments and the stability property demonstrate that the proposed scheme is stable and accurate. A TE mode wave is used to validate the proposed technique. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 212–215, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21308
Wideband MIMO measurements of outdoor NLOS channels
Authors: Yang Yaoqing , Xu Guanghan , Ling Hao
Published: December 2005

The measurement results of the wideband wireless multiple‐input multiple‐output (MIMO) channels in outdoor environments are presented. Our wideband wireless MIMO channel sounder consists of four transmitters and eight receivers, and operates at a carrier frequency of 1.8 GHz with a bandwidth of 2.5 MHz. After obtaining the multipath delay profiles from the data collected in non‐line‐of‐sight (NLOS) environments, realistic wideband MIMO channel capacities are computed and compared with the ideal channel simulation. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 216–218, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21309
Experimental study of ultra‐broadband patch antenna using a wedge‐shaped air substrate
Authors: Yao Feng‐Wei , Zhong Shun‐Shi , Liang Xian‐Ling
Published: December 2005

In this paper, an ultra‐broadband patch antenna using a wedge‐shaped air dielectric substrate is introduced. By adjusting the angle α, the experimental ratio bandwidth of S11 ⩽ −10 dB reaches 8.8:1, covering frequencies from 3.05 to 26.87 GHz. The measured impedance locus and radiation patterns at f = 6 GHz and at f = 18 GHz both are presented, and they show broadband characteristics and stability across the whole operating frequency bands, respectively. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 218–220, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21310
Internal patch antenna with an inset shielding metal case for mobile‐device application
Authors: Wong Kin‐Lu , Tseng Ting‐Chih
Published: December 2005

An internal patch antenna integrated with an inset shielding metal case for application in a mobile device is presented. The internal patch antenna is achieved by mounting a top radiating patch above the system ground plane of a mobile device and further short‐circuiting the top radiating patch to a shielding metal case, which is mounted on the system ground plane and inset into the region below the top patch. Since the shielding metal case provides a coupling‐free space for the RF modules/circuitry and other associated components, the proposed design leads to a compact integration of the internal antenna and the associated components in the mobile device. Details of the proposed design applied to a mobile device for UMTS (Universal Mobile Telecommunications Systems, 1920–2170 MHz) operation are described, and the experimental results are presented and discussed. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 220–222, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21311
Wideband dielectric resonator antenna
Authors: Ruan Yu‐Feng , Guo Yong‐Xin , Shi Xiang‐Quan
Published: December 2005

This paper presents a new wideband dielectric resonator (DR) antenna. To enhance the bandwidth, two layers of stacked resonators having the same rotational axis of symmetry are used. At the bottom layer, a smaller cylindrical DR is placed concentrically inside a large annular‐ring DR, whereas at the top layer, there is only one cylindrical DR. A coaxial probe is placed off the antenna axis in the DR antenna in order to produce broadside far‐field radiation patterns. The effects of the antenna parameters such as dielectric constant, probe length, and excitation position as well as the air gap between the bottom layer of the stacked DRA and the ground plane are investigated numerically. A bandwidth up to 67% for a −10‐dB return loss is achieved for the proposed antenna. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 222–226, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21312
Analysis of adaptive antenna using electromagnetic band gap structure
Authors: Talleb H. , Lautru D. , Fouad Hanna V.
Published: December 2005

This paper presents the analysis of an adaptive antenna that is formed of a dipole antenna above a ground plane in the presence of electromagnetic band gap (EBG) metallic structures. Electromagnetic simulations are performed using the method of moments (MoM) and the obtained results show a good concordance with those that can be determined when using antenna‐array theory. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 226–229, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21313
Slow‐wave CPW resonator with defected ground structure (DGS) for filter applications
Authors: Akgün Özlem , Görür Adnan
Published: December 2005

Novel slow‐wave CPW resonators with defected ground structures (DGSs) in a rectangularly spaced and open‐loop shapes are investigated. These structures have an extremely compact size. The simulations and experimental results verify that these structures provide a size reduction of about 54% as compared to a conventional CPW resonator. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 229–233, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21314
A 2.4‐GHz wireless‐over‐fiber transceiver using photonic active integrated antennas (PhAIAs)
Authors: Cryan M. J. , Dragas M. , Kung J. , Jain V. , Fornetti F. , Houle T. , Varrazza R. , Hill M.
Published: December 2005

The integration of a vertical cavity surface emitting laser (VCSEL) and a photodiode with two microstrip antennas results in low‐cost wireless‐optical transmitter and receiver modules and the initial microwave‐link results are shown. The VCSEL antenna is used as part of a fully bidirectional wireless‐optical link and data are successfully transferred between two wireless‐enabled laptops. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 233–237, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21315
A normalized plane‐wave method for 2D Helmholtz problems
Authors: Bogaert Ignace , Pissoort Davy , Olyslager Frank
Published: December 2005

A new technique to diagonalize the 2D Green's function is presented. The new method, called the normalized plane‐wave method, is an extension of the plane‐wave method into the low‐frequency regime. As such, it provides a way to achieve 𝒪(𝒩) complexity for both low‐ as well as high‐frequency problems without having to resort to inhomogeneous plane‐wave methods. The accuracy of the proposed method is thoroughly tested and it is shown that it can be made as high as one may reasonably want in any of the frequency regimes. Furthermore, it is shown to be faster than the traditional fast‐multipole method (FMM) for low‐frequency problems, by virtue of diagonal translations. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 237–243, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21316
A method to generate a sparse matrix for thin‐wire structures using the method of moments
Authors: Bansal Hemant , Saxena Shashank , Singh Surendra , Waller Marsellas L. , Rao Sadasiva M.
Published: December 2005

In this work, a numerical procedure is presented to obtain a sparse moment matrix for thin‐wire electromagnetic scattering problems. The numerical procedure involves developing a set of basis functions spanning several subdomains, as opposed to spanning one or two subdomains in the conventional method of moments (MoM) procedure. The numerical results are presented for various wire structures (including wire junctions) and compared using the traditional MoM procedure. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:243–248, 2006; Published Online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21317
Distortion produced by RF MEMS varactors on digital communication signals
Authors: Lázaro Antonio , Girbau David , Pradell Lluís
Published: December 2005

This paper presents a study of the nonlinear effects introduced by MEMS varactors when excited with digitally modulated RF signals (QPSK and 16 QAM). The study is based on simulating a nonlinear model of the MEMS device using harmonic‐balance and envelope solvers, and on experimental measurements of the wave reflected by the on‐wafer MEMS device. It is shown that the adjacent‐channel power ratio (ACPR) and error‐vector magnitude (EVM) of the digital signal suffer a degradation due to the device nonlinear distortion. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:246–249, 2006; Published Online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21318
Comparing double‐negative and double‐positive covers around a radiating line current
Authors: Nelatury Sudarshan Rao
Published: December 2005

The power radiated by a line source per unit length, surrounded by a double‐negative (DNG) material is analytically found and compared with that obtained in case of a double‐positive (DPS) material. Results indicate that the presence of significant increase in the radiated power with a shift in resonance. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:250–252, 2006; Published Online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21319
Low‐power PHEMT MMIC LNA for C‐band applications
Authors: Yuk Jong Seol , Choi Byoung Gun , Lee You Sang , Park Chul Soon , Kang Sukhoon
Published: December 2005

We report on design and performance of a low‐power‐consuming two‐stage MMIC LNA using AlGaAs/GaAs pseudomorphic HEMTs with 0.25‐μm T‐gates. The MMIC LNA showing a noise figure of 2.55 dB with 17‐dB associated gain at 5.8 GHz consumes only 18 mW, which is the lowest value of power consumption ever reported to date from PHEMT MMIC LNAs around this frequency range, and is attributed to the optimization of the gate width and current, as well as the use of a circuit with a single current path. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:253–255, 2006; Published Online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21320
An empirical model for propagation‐loss prediction in indoor mobile communications using the Padé approximant
Authors: Fraiha Simone G. C. , Rodrigues Josiane C. , Barbosa Regiane N. S. , Gomes Hermínio S. , Cavalcante Gervásio P. S.
Published: December 2005

This paper presents a new model for propagation‐loss prediction in indoor mobile communications. It uses the free‐space loss model added to an empiric function (based on the Padé approximant), and a term that describes the signal randomness (typical of the RF propagation). In order to validate this model, a measurement verification was accomplished for a typical five‐floor building of a university. The loss predicted by this model had a mean error of 4.78 dB and a standard deviation of 6.05 dB in relation to the measured data. The formulation of the model does not require accurate information about the environment used in the study, such as the permittivity of the construction materials, layout of the furniture, and so forth, but only needs to be adaptable to any indoor environment. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:255–261, 2006; Published Online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21321
Modification to convolution CFS‐PML for the ADI‐FDTD method
Authors: Wang Linnian , Liang Changhong , Li Long
Published: December 2005

A new implementation of perfectly matched layer (PML) using the recursive‐convolution technique is introduced for an alternating‐direction implicit (ADI) finite‐difference time‐domain (FDTD) method. Based on a “complex frequency‐shifted (CFS)” scaling function, this PML boundary condition is highly effective at absorbing low‐frequency evanescent waves. The numerical results show that, compared with its previously suggested analogue, the new method improves the reflection error by 30 dB for large time‐step sizes. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 261–265, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21322