bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved impedance matrix compression (IMC) technique for efficient wavelet‐based method of moments solution of scattering problems
Authors: Sokolik Dmitry , Shifman Yair , Leviatan Yehuda
Published: January 2004

The iterative impedance matrix compression (IMC) method iteratively constructs and solves a reduced version of the method of moments (MoM) impedance matrix based on analysis of the error in fulfilling the original matrix equation. Hence, it is possible that some of the selected basis functions, while dominant in the analyzed error, will have very little weight in the solution itself. Here, we propose a backward elimination step, which is aimed at discarding these superfluous basis functions. To demonstrate this idea, we use the scattering problem of a TMzplane wave by a conducting cylinder of square cross‐section. The resultant compression ratio is in good agreement with the theoretical limit of the compression ratio obtained a posteriori, based on the exact MoM solution. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 275–280, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11351
Direct application of the S24 FDTD method to antenna pattern computation
Authors: Wu Wei‐Yang , Kuo Chin‐Wen
Published: January 2004

Directly applying the higher‐order FDTD method to the computation of antenna patterns has not been a practical approach thus far. One of the main difficulties is how to handle the perfect electric conductor (PEC), which is always present. This paper describes a procedure for handling the PEC using the S24 FDTD method, which is capable of directly computing the antenna far‐field patterns. Accuracy of the algorithm is demonstrated by comparing the antenna patterns with those calculated from the near‐to‐far field transformation and cavity model. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 289–292, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11355
Compact amplifier integrated microstrip antenna
Authors: Raj Rohith K. , Kundukulam Sona O. , Aanandan C. K. , Vasudevan K. , Mohanan P. , Kumar Praveen
Published: January 2004

A compact microstrip antenna integrated with an amplifier having an area reduction of 70%, compared to the standard circular microstrip patch antenna, is presented. The antenna also provides an enhanced gain of 10‐dB more than its passive counter part. The measured 2:1 VSWR band width is ∼4% at 790 MHz, which is 2.5 times larger than that of the passive microstrip antenna. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 296–298, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11358
A multiple‐building diffraction attenuation function expressed in terms of UTD coefficients for microcellular communications
Authors: Rodríguez José‐Víctor , Molina‐García‐Pardo José‐María , Juan‐Llácer Leandro
Published: January 2004

This work presents an explicit formulation for multiple‐edge diffraction for mobile radiowave propagation in terms of uniform theory of diffraction (UTD) coefficients when a spherical incident wave is considered. This solution can be used in an UTD context and sharply reduces the computing time over existing formulation. Results can be applied in the planning of microcellular systems. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 298–300, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11359
An efficient simulation technique for lossy substrate interconnects characterization
Authors: Wu Dagang , Chen Ji
Published: January 2004

In this paper, an efficient numerical simulation technique is introduced to extract the propagation characteristics of interconnects over lossy substrate structures. This approach is based on a compact‐form FDFD method in conjunction with the two‐step Lanczos (TSL) technique. The efficiency and accuracy of the algorithm are demonstrated through the simulation of several lossy transmission‐line structures. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 305–308, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11362
Parametric study of compact flat antennas based on periodic patterns
Authors: Pioch S. , Laheurte J.‐M.
Published: January 2004

The geometry of a microstrip antenna is altered by using a periodic pattern. The aperture‐coupled antenna is realized by combining 2 × 2 unit cells in a square geometry. A 33% reduction of the resonant frequency of the original plain patch is reached by locally increasing the inductance of the unit cell. Conversely, a 60% surface reduction of dimensions of the original antenna is observed for a given operating frequency. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 311–314, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11364
L‐band gain clamped erbium‐doped fiber amplifier incorporating a C/L‐band WDM coupler
Authors: Harun S. W. , Ahmad H.
Published: January 2004

Gain clamping in a long‐wavelength‐band erbium‐doped fiber amplifier (L‐band EDFA) using a C/L‐band WDM coupler is demonstrated. The gain for the amplifier is clamped at 15.5 dB with a gain variation of less than 0.2 dB from input signal power ranging from −40 to −14 dBm with almost negligible noise‐figure penalty. However, the flatness of the gain spectrum is slightly degraded due to the nonoptimisation of the EDF length. The advantage of this configuration is that the oscillating light does not appear at the output port of the amplifier. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 314–316, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11365
Novel wideband internal chip antenna for PCS/IMT‐2000 dual‐band applications
Authors: Yim D. S. , Kim J. , Park S. O.
Published: January 2004

A novel wideband internal chip antenna for KPCS/IMT‐2000 dual‐band applications is investigated experimentally and numerically. It has a wide bandwidth of about 21.4%, measured gain of 2.6 dBi, and an omnidirectional radiation pattern while retaining cost effectiveness and small size. These features make the proposed antenna highly suitable for handset applications. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 324–326, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11369
Metamaterial slabs coupling
Authors: Cory H. , Skorka O.
Published: January 2004

Metamaterial slab coupling to another metamaterial slab or to a dielectric slab is studied, taking into consideration regular trigonometric modes as well as hyperbolic modes. The first TM even mode has been given special attention, since it exhibits interesting filtering properties. The coupling coefficient frequency variation of the structures has been investigated. It is found that, for a given frequency, the thinner the width of the slabs or the lower their permittivity, the higher the coupling between them. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 340–344, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11373
A printed dipole antenna with microstrip tapered balun
Authors: Chen Guan‐Yu , Sun Jwo‐Shiun
Published: January 2004

In this design, the dipole antenna fed network with tapered balun is studied. The design and experimental results of low profile microstrip dipole antenna with tapered balun shows fairly good performances in this paper. The feed network with wide bandwidth and low power loss tapered microstrip line to overlap coplanar stripline (CPS) transition that provided unbalanced to balanced equal power of 180° phase difference. The achieved planar dipole antenna exhibits 19% of 10‐dB bandwidth. Full wave EM analyses shows good agreement with those experimental data. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 344–346, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11374
Relationships between peer interactive play and social competence in at‐risk preschool children
Authors: Gagnon Sandra Glover , Nagle Richard J.
Published: January 2004

Relationships between peer interactive play and social competence in a sample of preschool children (N = 85) considered at risk for academic difficulties were examined. Ratings of peer interactive play and social emotional development were collected from parents and teachers on the Penn Interactive Peer Play Scale and Vineland Social‐Emotional Early Childhood Scale. Multivariate techniques revealed significant correlations between parent and teacher ratings on the measures. Results are discussed within the context of conducting multifaceted, ecological assessments of preschool children. Implications for school psychologists are noted with regard to the important associations between peer interactive play and social–emotional development. The psychometric integrity of the PIPPS is further validated and extended beyond the initial standardization sample to include a sample of primarily Caucasian children living in a more rural area. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 173–189, 2004.
Replication of the Adjustment Scales for Children and Adolescents core syndrome factor structure
Authors: Canivez Gary L.
Published: January 2004

Independent examination and replication of the core syndrome factor structure of the Adjustment Scales for Children and Adolescents (ASCA; McDermott, Marston, & Stott, 1993) is reported. A sample of 1,020 children were randomly selected from their classroom and rated on the ASCA by their teacher. The six ASCA core syndromes produced a two‐factor solution through principle axis analysis using multiple criteria for the number of factors to extract and retain. Varimax, direct oblimin, and promax rotations produced identical results and nearly identical factor structure coefficients. It was concluded that the ASCA indeed measures two independent dimensions of psychopathology (Overactivity and Underactivity) that are similar to the conduct problems/externalizing and withdrawal/internalizing dimensions commonly found in the child psychopathology assessment literature (Cicchetti & Toth, 1991; Quay, 1986). © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 191–199, 2004.
School psychology and issues of sexual orientation: Attitudes, beliefs, and knowledge
Authors: Savage Todd A. , Prout H. Thompson , Chard Kathleen M.
Published: January 2004

The purpose of this study was to investigate school psychologists' attitudes toward lesbians and gay males. Aspects of school psychologists' knowledge, beliefs, current practices, and levels of preparedness related to issues of sexual orientation were also explored. A sample of 288 school psychologists (215 females and 73 males, mean age = 44 years) who were members of NASP participated in this study. Participants completed research packets containing a hypothetical case analogue vignette and three questionnaires querying their attitudes, beliefs, and knowledge about issues of sexual orientation. The results indicated school psychologists endorse relatively positive attitudes toward lesbians and gay males, report low‐to‐moderate levels of knowledge about lesbian and gay male issues, are willing to address lesbian and gay male issues on the job, are generally aware of how such issues impact schools, and are inadequately prepared to deal with lesbian and gay male issues. These findings are discussed in relation to their impact on the field and the implications for graduate training. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 201–210, 2004.
Influences on teacher education student attitudes toward youth who are HIV+
Authors: Stinnett Terry A. , Cruce Michael K. , Choate Kurt T.
Published: January 2004

The expectations, attributions, and reactions toward children and youth who have contracted HIV/AIDS warrant close attention from parents, teachers, related service personnel, and others who will interact with these students in the schools. Those who are misinformed or unaware of their beliefs may inadvertently discriminate against children and youth with the disease. This study examined factors that influence judgments about children and youth with HIV/AIDS in a sample of teacher education students. Course of infection of HIV accounted for significant differences in the participants' judgments about responsibility and blame for contracting the disease and also fearfulness and attitudes reflecting isolation for these youth. Educational professionals should be aware of the many negative attributions placed on adolescents who are diagnosed as HIV+ and be prepared to act as facilitators when designing appropriate interventions to assist these students. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 211–219, 2004.
American and Chinese children's understanding of basic relational concepts in directions
Authors: Zhou Zheng , Boehm Ann E.
Published: January 2004

Two hundred first‐ and second‐grade Chinese children's knowledge of basic relational concepts in following directions was assessed on the Applications Booklet of the Boehm Test of Basic Concepts‐Revised (BTBC‐R, 1986). Chinese children's performance was then compared with that of the standardization sample of the BTBC‐R. Results indicated that both the American and Chinese children made significant improvements between the end of first and second grades, yet both American and Chinese children experienced difficulties on items such as following multiple‐step directions. American children, but not Chinese children, had difficulties following directions involving the concepts of right and left in combination with other relational concepts, the quantity concept of equal, and comparative and superlative features such as farther and farthest. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 261–272, 2004.
The ADHD label, analogue methodology, and participants' geographic location on judgments of social and attentional skills
Authors: Koonce Danel A. , Cruce Michael K. , Aldridge Jennifer O. , Langford Courtney A. , Sporer Amy K. , Stinnett Terry A.
Published: January 2004

Two hundred fifty‐nine preservice teachers at a medium‐sized university in the Southwest participated in the current study. The participants were randomly assigned to a labeled condition, Attention Deficit Hyperactivity Disorder, or nonlabeled condition, and were presented a vignette in one of three forms: a written case study, a video clip, or a written case study with a video clip. The vignette described an elementary school aged child displaying disruptive behavior, while the video portrayed a similar aged child exhibiting disruptive behavior in the classroom. Following the presentation of the vignette, participants made judgments about the child's social skills and attentional skills by completing an examiner‐made rating scale. There was a significant main effect for the label condition on judgments of attention; participants in the labeled condition made significantly more negative judgment than did those in the nonlabeled condition. There were also significant main effects for the participants' high school location and vignette treatment. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 221–234, 2004.
A comparison of teacher checklists used over 15 days and a one‐day antecedent analysis to conduct a medication trial
Authors: Smith R. , Larsen D. , Derby K.M. , McLaughlin T.F. , Weber K.P. , Brown K. , Herring M.
Published: January 2004

A one‐day antecedent analysis and an extended school‐based double‐blind medication trial were used to assess the effects of Ritalin on the disruptive behavior of a child diagnosed with ADHD. The evaluations took place in an outpatient clinic and in the child's general education classroom. The results of both evaluations indicated that the medication had a positive effect on reducing disruptive behaviors. The investigation suggests that the one‐day antecedent analysis procedure could be used as an initial evaluation of the use of Ritalin. More importantly, the one‐day trial provided results similar to the outcomes obtained during the school‐based evaluation. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 235–240, 2004.
Silent versus oral reading comprehension and efficiency
Authors: McCallum R. Steve , Sharp Shannon , Bell Sherry Mee , George Thomas
Published: January 2004

Seventy‐four students read passages from an individually administered test of reading comprehension (a subtest from the Test of Dyslexia, a test of reading and related abilities currently in development; McCallum & Bell, 2001), and then answered literal and inferential questions. Students were randomly assigned to one of two conditions; 39 students read the passages silently and 35 read orally, with time recorded for each passage read. Comprehension and time were dependent measures for a Multivariate Analysis of Covariance (MANCOVA) and two follow‐up Analyses of Covariance (ANCOVA). After controlling for reading ability, results from the MANCOVA showed a significant combined effect ( p < .05); however, a comparison of mean reading comprehension scores showed no significant difference between silent readers and oral readers ( p > .05). On the other hand, with reading ability controlled, silent readers took significantly less time to complete passages compared to those who read orally ( p < .02). In fact, students took 30% longer to read orally than silently, on average. When test directions do not specify either oral or silent reading and error analysis is not a goal, testing will be more efficient via silent responding with no loss of comprehension. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 241–246, 2004.
Attachment theory: Implications for school psychology
Authors: Kennedy Janice H. , Kennedy Charles E.
Published: January 2004

The effective practice of school psychology requires a strong research and theoretical base, a framework that encompasses developmental processes and outcomes, both adaptive and maladaptive, which facilitates assessment and intervention and offers insight into classroom and family dynamics. Attachment theory provides the school psychologist with just such a framework. In the present article we provide a brief overview of attachment theory and describe risk factors for development of insecure attachment. Behavioral trajectories of children and adolescents according to attachment classification are discussed. Finally, student–teacher interactions within an attachment perspective and implications for interventions are presented. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 247–259, 2004.
Solvent‐ and interface‐induced surface segregation in blends of isotactic polypropylene with poly(ethylene‐co‐propylene) rubber
Authors: Opdahl Aric , Phillips Roger A. , Somorjai Gabor A.
Published: January 2004

The surface compositions and morphologies of melt‐quenched blends of isotactic polypropylene (iPP) with aspecific poly(ethylene‐co‐propylene) rubber (aEPR) were characterized by atomic force microscopy, optical microscopy, and X‐ray photoelectron spectroscopy. The surface morphologies and compositions formed in the melt are frozen‐in by crystallization of the iPP component and, depending on the processing conditions, are enriched in iPP or aEPR or contain a phase‐separated mix of iPP and aEPR. Enrichment of iPP is observed for blends melted in open air, in agreement with earlier work showing the high surface activity of atactic polypropylene at open interfaces. Surface segregation of iPP is suppressed at confined interfaces. Blends melt‐pressed between hydrophilic and hydrophobic substrates have phase‐separated iPP and aEPR domains present at the surface, which grow in size as the melt time increases. Surface enrichment of aEPR is observed after exposing melt‐pressed blends to n‐hexane vapor, which preferentially solvates aEPR and draws it to the surface. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 421–432, 2004
Structure and properties of regenerated cellulose/tourmaline nanocrystal composite films
Authors: Ruan Dong , Zhang Lina , Zhang Zhenjun , Xia Xinming
Published: January 2004

Nanocomposite films were successfully prepared from cellulose and tourmaline nanocrystals with mean diameters of 70 nm in a 1.5 M NaOH/0.65 M thiourea aqueous solution by coagulation with 5 wt % CaCl2 and then a 3 wt % HCl aqueous solution for 2 min. The structure and properties of the composite films were characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and tensile testing. The results indicated that the tourmaline nanocrystals were dispersed in a cellulose matrix, maintaining the original structure of the nanocrystals in the composite films. The loss peaks (tan δ) in the DMA spectra and the decomposition temperatures in the DSC curves of the composite films were significantly shifted toward low temperatures, suggesting that the nanocrystals broke the partial intermolecular hydrogen bonds of cellulose, and this led to a reduction in the thermal stability. However, the nanocomposite films exhibited a homogeneous structure and dispersion of the nanocrystals. When the tourmaline content was in the range of 4–8 wt %, the composite films possessed good tensile strength (92–107 MPa) and exhibited obvious antibacterial action against Staphylococcus aureus. This work provides a potential way of preparing functional composite films or fibers from cellulose and nanoinorganic particles with NaOH/thiourea aqueous solutions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 367–373, 2004
Effects of crosslinking agent, cure temperature, and UV flux on the electro‐optical properties of polymer‐dispersed liquid crystal cells
Authors: Henry R. M. , Ramsey R. A. , Sharma S. C.
Published: January 2004

We present results for the effects of a crosslinking agent, cure temperature, and UV flux on the electro‐optical properties of polymer‐dispersed liquid crystal (PDLC) cells. These cells were fabricated using a mixture of a liquid crystal (E8) and an acrylic monomer (CN135). The maximum in the first derivative of the transmission vs. applied, sinusoidal voltage (inflection voltage, Vinf), varies systematically with PDLC formulation and cure‐process conditions. For PDLC cells fabricated with a crosslinking agent (SR295), Vinf increases with increasing the concentration of SR295. However, for cells fabricated without the use of a crosslinking agent, Vinf decreases with increasing the UV flux and decreasing temperature. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 404–410, 2004
Free volume and oxygen transport in cold‐drawn polyesters
Authors: Liu R. Y. F. , Hiltner A. , Baer E.
Published: January 2004

Poly(ethylene terephthalate) (PET), poly(ethylene terephthalate‐co‐4,4′‐bibenzoate) (PETBB55), and poly(ethylene 2,6‐naphthalate) (PEN) were cold‐drawn to achieve uniform extension without crystallization or stress whitening, and oxygen transport properties were studied at temperatures from 10 to 40 °C. Correlation of oxygen solubility and polymer specific volume made it possible to consider the oriented polyester as a one‐phase densified glass. Orientation was viewed as decreasing the amount of excess‐hole free volume and bringing the nonequilibrium polymer glass closer to the equilibrium condition. Between 10 and 40 °C, the amount of excess‐hole free volume in PET decreased as the polymer approached the glass transition temperature. In contrast, temperature changes in this range had little effect on the excess‐hole free volume in PETBB55 and PEN, which were well below their glass transition temperature. Gas diffusion was viewed as discrete jumps of the oxygen molecule between holes of excess‐free volume. The jump length was extracted from the activation energy for diffusion according to a channel‐formation model. The result agreed well with the hole spacing estimated from a simple lattice model using the hole density reported in the literature. Extending the lattice model to estimate the mean excess‐free volume hole radius from the fractional free volume resulted in good correlation with the hole radius obtained from positron annihilation lifetime spectroscopy. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 493–504, 2004
Managing polymer surface structure using surface active block copolymers in block copolymer mixtures
Authors: Hexemer A. , Sivaniah E. , Kramer E. J. , Xiang M. , Li X. , Fischer Daniel A. , Ober C. K.
Published: January 2004

Surface coatings were prepared from semifluorinated monodendron surface‐active block copolymers (SABC) and a thermoplastic elastomer (TPE) [poly(styrene‐b‐ethylene butylene‐b‐styrene)] by either spin‐casting a bilayer structure or by blending. The surface of these coatings was characterized by contact angle measurements, scanning force microscopy (SFM) and near‐edge X‐ray absorption fine structure (NEXAFS) methods. Both bilayers and blends resulted in very low energy surfaces under the right processing conditions and the liquid crystallinity of the semifluorinated monodendrons gave rise to temporally stable, non‐reconstructing surfaces in water. However for small thicknesses of the SABC top layer or for low SABC content blends, SFM shows islands of the fluorinated block of the SABC and incomplete surface coverage of the TPE, an observation confirmed by NEXAFS analysis. Very high water contact angles were produced by even modest amounts of SABC in either case but to achieve low contact angle hysteresis, it was necessary to produce uniform surface coverage by the SABC. Such uniform coverage can be accomplished by spin casting a top layer of SABC as thin as 60 nm in the bilayer case but at least 10 wt% SABC in TPE combined with drop casting of a hot solutions is needed for the blends to achieve equivalent surface structure and properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 411–420, 2004
Dynamic and equilibrium swelling of a sulfonic acid superabsorbent copolymer in salt solutions
Authors: Rosa Fátima , Bordado João , Casquilho Miguel
Published: January 2004

Superabsorbent copolymers were synthesized by free radical reverse emulsion from the monomers acrylamide and 2‐acrylamido‐2‐methyl‐propanosulfonic acid with a divinyl crosslinker (methylene‐bisacrylamide). The copolymer synthesized was then identified by Fourier transform infrared spectroscopy, its porosity was examined by electronic microscopy, and its specific gravity was determined by the conventional procedure. The dynamic and equilibrium swelling behavior of the copolymer was studied, in water and in salt solutions, at 25 °C (chlorides and sulfates of sodium and magnesium). As to the equilibrium swelling, the influence of the pH as well as of the salt type and its concentration was observed. As to the dynamic swelling, it was interpreted in terms of both a simple power of time equation, and a more detailed model based on a coupled diffusion‐relaxation mechanism. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 505–514, 2004
Water transport properties of thermoplastic polyurethane films
Authors: Dolmaire N. , Espuche E. , Méchin F. , Pascault J.‐P.
Published: January 2004

Two linear segmented polyurethanes, based on poly(oxyethylene) (POE) as a soft segment and 4,4′‐diphenylmethane diisocyanate and 1,4‐butanediol as hard segments and differing in their soft segment length, have been studied from a water vapor transport point of view. For both polyurethanes, the water sorption is governed by a Fickian process, and the thermoplastic polyurethane with the longer POE segments displays the higher water diffusion rate. The water sorption isotherms are Brunauer Emmet Teller (BET) type III for both thermoplastic polyurethanes, and the water uptakes are directly related to the polymer POE content. The Flory–Huggins theory cannot correctly describe the sorption isotherms. More sophisticated approaches (Koningsveld–Kleinjtens or Guggenheim‐Anderson‐de Boer (GAB) models) are needed to fit the experimental water uptakes. The positive deviation from Henry's law and the decrease in the apparent diffusion coefficient observed at a high activity have been particularly studied. In this activity range, an isotherm analysis based on the cluster integral of Zimm and Lundberg suggests some clustering phenomenon, which seems consistent with the diffusion coefficient variation. In agreement with the sorption results, the water permeability coefficients are small at low activities, and they increase greatly with the relative pressure of water. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 473–492, 2004
Poly(thiodiethylene adipate): Melting behavior, crystallization kinetics, morphology, and crystal structure
Authors: Finelli L. , Lotti N. , Munari A. , Gazzano M. , Malta V.
Published: January 2004

The melting behavior and crystallization kinetics of poly(thiodiethylene adipate) (PSDEA) were investigated with differential scanning calorimetry and hot‐stage optical microscopy. The observed multiple endotherms, commonly displayed by polyesters, were influenced by the crystallization temperature (Tc) and ascribed to melting and recrystallization processes. Linear and nonlinear treatments were applied to estimate the equilibrium melting temperature for PSDEA with the corrected values of the melting temperature. The nonlinear estimation yielded a higher value by about 9 °C. Isothermal crystallization kinetics were analyzed according to Avrami's treatment. Values of Avrami's exponent close to 3 were obtained, independently ofTc, in agreement with a crystallization process originating from predetermined nuclei and characterized by three‐dimensional spherulitic growth. As a matter of fact, space‐filling spherulites were observed by optical microscopy at allTc's. The rate of crystallization became lower asTcincreased, as usual at a low undercooling, the crystallization process being controlled by nucleation. Moreover, the crystal structure of PSDEA was determined from powder X‐ray diffraction data by full profile fitting. A triclinic unit cell containing two polymer chains arranged parallel to thecaxis was found. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 553–566, 2004
Surface modification of ultrahigh‐molecular‐weight polyethylene fibers
Authors: Zheng Zhen , Tang Xiaozhen , Shi Meiwu , Zhou Guotai
Published: January 2004

To prevent the loss of fiber strength, ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers were treated with an ultraviolet radiation technique combined with a corona‐discharge treatment. The physical and chemical changes in the fiber surface were examined with scanning electron microscopy and Fourier transform infrared/attenuated total reflectance. The gel contents of the fibers were measured by a standard device. The mechanical properties of the treated fibers and the interfacial adhesion properties of UHMWPE‐fiber‐reinforced vinyl ester resin composites were investigated with tensile testing. After 20 min or so of ultraviolet radiation based on 6‐kW corona treatment, the T‐peel strength of the treated UHMWPE‐fiber composite was one to two times greater than that of the as‐received UHMWPE‐fiber composite, whereas the tensile strength of the treated UHMWPE fibers was still up to 3.5 GPa. The integrated mechanical properties of the treated UHMWPE fibers were also optimum. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 463–472, 2004
Polypropylene/polystyrene blends: In situ compatibilization by Friedel‐Crafts alkylation reaction
Authors: Díaz Mónica F. , Barbosa Silvia E. , Capiati Numa J.
Published: January 2004

The application of Friedel‐Crafts alkylation reaction to the compatibilization of polypropylene (PP)/polystyrene (PS) blends was assessed. A PP macrocarbocation is chemically bonded to the PS benzene ring by aromatic electrophilic substitution. The graft copolymer formed at the interphase (PP‐g‐PS) showed relatively high emulsification strength, suggesting an effective behavior as in situ compatibilizer. The critical micelle concentration (CMC) was related to Friedel‐Crafts catalyst concentration. The amount of PS grafting and possible appearance of crosslinking and chain scission side reactions were also analyzed. The reaction products were characterized by a combination of size exclusion chromatography and Fourier transform infrared techniques applied after a careful solvent extraction separation. It was found, from the emulsification curve, that CMC was achieved when 0.7 wt % AlCl3 was added. This value was confirmed by scanning electron microscopy observation of phase adhesion on fractured sample surfaces. Mass balances of extracted PS showed that at least 15 wt % of the initial PS resulted grafted at the CMC condition. Chain scission reactions, in parallel with grafting, were verified to occur for PP as well as for PS. Instead, crosslinking reactions were not detected. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 452–462, 2004
Ultrasonic degradation of solutions of poly(vinyl acetate) in dioxan: The effects of the temperature and polymer concentration
Authors: Taghizadeh Mohammad Taghi , Mehrdad Abbas
Published: January 2004

The ultrasonic degradation of poly(vinyl acetate) (PVAc) solutions was carried out in dioxan at 25, 30, 35, 40, and 45 °C to investigate the effects of the temperature and solution concentration on the rate of degradation. The kinetics of degradation were studied by viscometry. The calculated rate constants indicated that the degradation rate of the PVAc solutions decreased as the temperature and solution concentration increased. The calculated rate constants were correlated in terms of the concentration, temperature, vapor pressure of dioxan, and relative viscosity of the PVAc solutions. This degradation behavior was interpreted in terms of the vapor pressure of dioxan, the viscosity, and the concentration of the polymer solutions. With increasing temperature, the vapor pressure of the solvent increased, and so the vapor entered the cavitation bubbles during their growth. This caused a reduction in collapsing shock because of a cushioning effect; therefore, the rate of degradation decreased. As the solution concentration increased, the viscosity increased and caused a reduction in the cavitation efficiency, and so the rate of degradation decreased. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 445–451, 2004
Radioimmunotherapy of prostate cancer in human xenografts using monoclonal antibodies specific to prostate specific membrane antigen (PSMA): Studies in nude mice
Authors: Vallabhajosula Shankar , Smith‐Jones Peter M. , Navarro Vincent , Goldsmith Stanley J. , Bander Neil H.
Published: January 2004

BACKGROUND

Prostate specific membrane antigen (PSMA), expressed by virtually all prostate cancers is an ideal target for targeted therapy of prostate cancer. Radiolabeled J591 monoclonal antibody (MAb) binds with high affinity to an extracellular epitope of PSMA and localizes specifically in PSMA positive LNCaP tumors in vivo.

METHODS

Pre‐clinical radioimmunotherapy (RIT) studies using 131I‐huJ591 and 90Y‐1,4,7,10‐tetraazacyclododecane‐N,N′,N′′,N′′′‐tetraacetic acid (DOTA)‐huJ591 MAbs were studied in nude mice bearing LNCaP xenografts.

RESULTS

A 15–90% reduction in mean tumor volume was observed after a single dose of 131I‐huJ591 (3.7–11.1 MBq) or 90Y‐DOTA‐huJ591 (3.7–7.4 MBq). The median survival time increased 2–3 times relative to untreated controls. Multiple administrations of fractionated doses of 90Y‐DOTA‐huJ591 were even more effective with minimal toxicity. Radiation dose to blood and tumor was higher with 90Y than with 131I. The maximum tolerated dose (MTD) is 5.55 MBq for 90Y‐DOTA‐huJ591 and more than 11.1 MBq for 131I‐huJ591. For 90Y‐DOTA‐huJ591 at MTD, dose to the tumor was 2,753 cGy.

CONCLUSIONS

In nude mice bearing PSMA positive tumors, radiation dose to the tumor with 90Y‐DOTA‐J591 is greater for large tumors than with 131I‐J591. The theoretical and practical considerations strongly suggest that 90Y‐DOTA‐huJ591 may be a suitable radiopharmaceutical for the treatment of prostate cancer. © 2003 Wiley‐Liss, Inc.
Response to sublethal heat treatment of prostatic tumor cells and of prostatic tumor infiltrating T‐cells
Authors: Kramer Gero , Steiner Georg E. , Gröbl Marion , Hrachowitz Kristian , Reithmayr Franz , Paucz Ljubomir , Newman Martin , Madersbacher Stephan , Gruber Diego , Susani Martin , Marberger Michael
Published: January 2004

BACKGROUND

To investigate the possibilities offered by high intensity focused ultrasound (HIFU) in the field of tumor vaccination, we analyzed how prostatic cancer (CaP) cells react towards heat treatment and whether increased access to CaP cells by the immune system would be the result.

METHODS

Heat/stress response of CaP cells in situ and of CaP cell lines was analyzed by immunohistochemistry, Western blotting, and Atlas array. A heat‐induced change in immune recognition was analyzed functionally using human T‐helper (Th)1 and Th2‐cytokine release with tumor infiltrating T‐lymphocytes (TIL) as responder and autologous CaP cells either heated or untreated as stimulator cells.

RESULTS

Transcription of 68 out of 500 genes was upregulated by sublethal heat in LNCaP and PC3 cells. Significantly upregulated stress protein (SP) expression (HSP‐72, ‐73, GRP‐75, ‐78) was seen at the border zone of HIFU treatment. Remarkably, even untreated benign prostatic hyperplasia (BPH) specimens revealed relative overexpression of heat shock protein (HSP)‐72, ‐73 and glucose regulated protein (GRP)‐75, ‐78. Heated CaP cells increased Th1‐cytokine (IL‐2, IFN‐γ, TNF‐α) release but decreased Th2‐cytokine (IL‐4, ‐5, ‐10) release of TIL.

CONCLUSIONS

HIFU treatment may alter the presentation of prostate tissue and tumor antigens and this presentation is most likely stimulatory. HSP‐72/73 overexpression in untreated BPH may suggest a mechanism by which BPH can incite inflammation. © 2003 Wiley‐Liss, Inc.
Analysis of the inflammatory network in benign prostate hyperplasia and prostate cancer
Authors: König Jens Ekkehard , Senge Theodor , Allhoff Ernst Peter , König Wolfgang
Published: January 2004

INTRODUCTION

The complexity of acute and chronic inflammatory processes may either lead to benign prostate hyperplasia (BPH) and/or prostate cancer. Obviously, various tissue cells are activated by chemokines via different chemotaxin receptors which then trigger subsequent processes in angiogenesis, cellular growth, and extravasation as well as neoplasia.

METHODS

Using the surgically obtained tissue of patients (n = 36) with BPH or prostate carcinoma (PCA), we studied among others the expression of chemokines (Rantes, IL‐8), chemotaxin receptors (CXCR‐3 and ‐4, CCR‐3, CCR‐5), of matrixmetalloproteinases (MMP‐2 and 9), of Toll‐like (TL) receptors 1, 2, 3, 4, 5, 7, and 9 and of the inducible cyclooxygenase‐2 (cox‐2) by RT‐PCR. Further support for the different properties of tissue from PCA was obtained using two different PCA cell lines (PC3 = androgen resistant cell) or LNCAP cells (androgen sensitive) with emphasis on IL‐8, Il‐6, and PGE2 release. Cell lines were stimulated with either the tumor necrosis factor‐α (TNF‐α) and lipopolysacharide (LPS) over time. In addition to cytokine release, the quantification of mRNA by lightcycler for cox‐2, IL‐6, and IL‐8 was performed on these cell lines.

RESULTS

Remarkable differences in expression were obtained by RT‐PCR when BPH tissue versus PCA was analyzed. Expression of CXCR‐1 after incubation with LPS and TNF‐α showed time‐dependent differences for androgen‐sensitive LNCAP as compared to androgen‐resistant PC‐3 cells. TNF‐α incubation leads to a time‐dependent induction of cox‐2 expression unlike to activation with LPS. Differences with regard to cox‐2, IL‐6, and IL‐8 expression were seen by quantitative lightcycler analysis. Significant differences were also observed when TL receptors 4, 5, 7, and 9 were analyzed which were significantly expressed in BPH‐ as compared to PCA‐tissue.

CONCLUSIONS

Our data clearly demonstrate that various inflammatory and cell biological cascades are involved which either lead to BPH or can be linked to the development of PCA. The exact cell biological mechanisms may provide novel therapeutic options in the treatment of both diseases. © 2003 Wiley‐Liss, Inc.
Comparative analysis of prostate‐specific membrane antigen (PSMA) versus a prostate‐specific membrane antigen‐like gene
Authors: O'Keefe Denise S. , Bacich Dean J. , Heston Warren D.W.
Published: January 2004

BACKGROUND

Currently prostate‐specific membrane antigen (PSMA) is showing promise both as an imaging and therapeutic target for occult prostate cancer metastases. First generation antibodies against PSMA are used for the FDA approved Prostascint™ monoclonal antibody scan and second generation antibodies are being developed for therapeutic targeting as well as imaging 1. However, there have been reports describing PSMA expression in non‐prostatic tissues including kidney, liver, and brain. As we had previously showed the existence of a human PSMA homolog, we set out to determine if this non‐prostatic expression was due to expression of the PSMA or another gene.

MATERIALS AND METHODS

The PSMA homolog (PSMA‐like) cDNA was cloned by screening a liver cDNA library. mRNA expression of the PSMA and PSMA‐like genes was determined via Northern blot analysis using two different probes and protein expression confirmed in some tissues via Western blot analysis. Transcriptional regulation of the two genes was examined using reporter constructs driving luciferase expression.

RESULTS

The PSMA‐like gene possesses 98% identity to the PSMA gene at the nucleotide level and is expressed in kidney and liver under the control of a different promoter to the PSMA gene. The PSMA gene is expressed in several human tissues and is most abundant in the nervous system and the prostate.

CONCLUSION

The non‐prostatic expression of PSMA should be taken into consideration when designing clinical strategies targeting PSMA. © 2003 Wiley‐Liss, Inc.
Expression of vascular endothelial growth factor receptor‐3 (VEGFR‐3) in human prostate
Authors: Li Rile , Younes Mamoun , Wheeler Thomas M. , Scardino Peter , Ohori Makato , Frolov Anna , Ayala Gustavo
Published: January 2004

BACKGROUND

The growth and dissemination of tumors has been associated with angiogenesis, which is regulated by a group of polypeptide factors including vascular endothelial growth factor‐C (VEGF‐C). VEGF‐C binds its receptor, vascular endothelial growth factor receptor‐3 (VEGFR‐3) to promote growth of tumor‐associated lymphatic vessels.

METHODS

In this study, microarray technology was used to build tissue arrays of normal prostate, benign prostate hyperplasia (BPH) and prostate carcinomas (PCa) using tissues from 640 patients. Slides were sectioned and stained with a polyclonal antibody to VEGFR‐3 using a standard immunoperoxidase method and digitized. Immunoreactivity was scored using a 0–3+ semiquantitation scoring system for both intensity and percentage. The sum index was obtained by totaling the scores.

RESULTS

VEGFR‐3 is expressed in normal prostate, BPH, and PCa, but VEGFR‐3 expression is up‐regulated in PCa. We also found that VEGFR‐3 is correlated with pre‐operative prostate‐specific antigen (Pre‐PSA), Gleason score, and lymph node metastasis. The recurrence‐free 5‐year survival in cases with lower sum index (0–3) was significantly higher than that in cases with higher sum index (4–6) (77.3, 69.6%, respectively, P = 0.037) by Kaplan–Meier actuarial model.

CONCLUSIONS

Our data suggest that VEGFR‐3 expression is associated with tumor progression and may play an important role in facilitating lymphatic spread of PCa; high‐level of VEGFR‐3 expression in prostate cancer cells increases the risk of biochemical recurrence in prostate cancer patients treated by radical prostatectomy. © 2003 Wiley‐Liss, Inc.
Amphiregulin expression in prostatic intraepithelial neoplasia and adenocarcinoma: A study of 93 cases
Authors: Bostwick David G. , Qian Junqi , Maihle Nita J.
Published: January 2004

BACKGROUND

Amphiregulin (AMP) is a heparin‐binding glycoprotein that is structurally and functionally related to epidermal growth factor. Its effects are mediated by the tyrosine kinase activity of the epidermal growth factor receptor (EGF‐R), and specific nuclear targeting sequences. AMP induces cell proliferation after androgen stimulation of human prostate cancer cell lines. An autocrine proliferative loop involving AMP, androgen, and EGF‐R may, therefore, play a role in prostatic carcinogenesis. The purpose of this study was to compare the expression of AMP in benign prostatic epithelium, high‐grade prostatic intraepithelial neoplasia (PIN), and adenocarcinoma.

METHODS

We performed an immunohistochemical study of select sections from 93 radical prostatectomies performed at the Mayo Clinic between 1987 and 1991. All patients were previously untreated and found to have pathologic stage T2N0M0 adenocarcinoma after routine handling of surgical specimens. Affinity‐purified polyclonal antibody directed against AMP was applied to tissue sections using the streptavidin‐biotin method. For each case, the percentage of immunoreactive cells in benign epithelium, PIN, and adenocarcinoma was estimated in 10% increments. Intensity on a scale from 0 (negative) to 3 (strongly immunoreactive) and pattern of expression (nuclear versus cytoplasmic) also were recorded.

RESULTS

AMP immunoreactivity was present in benign prostatic epithelium, PIN, and prostatic adenocarcinoma in all cases. The mean percentage of AMP‐immunoreactive cells was 53.8% in benign epithelium, 65.9% in PIN, and 74.3% in cancer. Intensity was moderate in all cases. The pattern of expression was usually nuclear in benign epithelium (secretory and basal cells), and usually cytoplasmic or nuclear and cytoplasmic in PIN and adenocarcinoma. There were rare scattered immunoreactive cells in the stroma, ejaculatory duct epithelium, and urethral urothelium. Endothelial cells were invariably unstained.

CONCLUSIONS

AMP expression in prostate increases progressively from benign epithelium to PIN and cancer. Increased expression of AMP may contribute to the development of prostatic adenocarcinoma. Predominantly nuclear staining was observed in benign epithelium, whereas cytoplasmic or nuclear and cytoplasmic staining was observed in PIN and adenocarinoma. The differences in nuclear and cytoplasmic localization of immunoreactivity may reflect the presence of two pathways of activation, and hence varying biological functions of AMP. © 2003 Wiley‐Liss, Inc.
Use of the Gleason system in international comparisons of prostatic adenocarcinomas in blacks
Authors: Freeman Vincent L. , Coard Kathleen C.M. , Wojcik Eva , Durazo‐Arvizu Ramon
Published: January 2004

BACKGROUND

Comparisons of prostate cancer in blacks living in different countries can shed light on factors responsible for high rates of the disease among blacks in America. Since the prognostic value of the Gleason grading system is well established, we assessed agreement between pathologists in countries where black populations of the African Diaspora reside.

METHODS

Three genitourinary pathologists at hospitals in Nigeria, Jamaica, and the US independently assessed sextant biopsies from 12 patients. Gleason sum and percentage involvement were recorded, and a percent‐weighted average calculated. Agreement under different groupings was evaluated using the kappa statistic generalized to three raters.

RESULTS

Agreement was significant for individual sums (κ = 0.3317, P = 0.0173), sums grouped as well (2–4), moderately (5–6), and poorly differentiated (7–10) (κ = 0.2437, P < 0.0001) and other groupings. Agreement between at least two raters was 91.7–100%; complete agreement was 41.7–66.7%.

CONCLUSIONS

The Gleason system is feasible and practical for international studies of prostate cancer among blacks from contrasting environments. Published 2003 Wiley‐Liss, Inc.