bluuebunny/crossref_metadata_2025_split huggingface dataset:
Level by level equivalence and strong compactness
Authors: Apter Arthur W. 
Published: January 2004

AbstractWe force and construct models in which there are non‐supercompact strongly compact cardinals which aren't measurable limits of strongly compact cardinals and in which level by level equivalence between strong compactness and supercompactness holds non‐trivially except at strongly compact cardinals. In these models, every measurable cardinal κ which isn't either strongly compact or a witness to a certain phenomenon first discovered by Menas is such that for every regular cardinal λ > κ, κ is λ strongly compact iff κ is λ supercompact. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the linear Lindenbaum algebra of Basic Propositional Logic
Authors: Alizadeh Majid , Ardeshir Mohammad 
Published: January 2004

AbstractWe study the linear Lindenbaum algebra of Basic Propositional Calculus, called linear basic algebra. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Automorphism group actions on trees
Authors: Ivanov Alexandre , Kossak Roman 
Published: January 2004

AbstractWe study the situation when the automorphism group of a recursively saturated structure acts on an ℝ‐tree. The cases of (ℚ, <) and models of Peano Arithmetic are central in the paper. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finitely generated submodels of an uncountably categorical homogeneous structure
Authors: Hyttinen Tapani 
Published: January 2004

AbstractWe generalize the result of non‐finite axiomatizability of totally categorical first‐order theories from elementary model theory to homogeneous model theory. In particular, we lift the theory of envelopes to homogeneous model theory and develope theory of imaginaries in the case of ω‐stable homogeneous classes of finite U‐rank. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transport and recombination dynamics studies of polymer/fullerene based solar cells
Authors: Choulis S.A. , Nelson J. , Tuladhar S.M. , Cook S. , Kim Y. , Durrant J.R. , Bradley D.D.C. 
Published: January 2004

AbstractWe have studied the electron/hole transport and recombination dynamics in blends of poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylene vinylene], (MDMO‐PPV) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) at room temperature, as a function of laser excitation density and PCBM concentration. The experimental results of these studies indicate the important role played by hole‐trap states in MDMO‐PPV. Electron and hole transport are not balanced within the blend. PCBM is a less disordered material than MDMO‐PPV and electron transport dominates the response of the solar cell device.
Voltage‐induced infrared spectra from polymer field‐effect transistors
Authors: Furukawa Yukio , Yamamoto Jun , Cho Don‐Chan , Mori Tatsuo 
Published: January 2004

AbstractCharge‐induced infrared absorption spectra from the metal‐insulator‐semiconductor diodes fabricated with aluminum oxide, poly(p‐xylylene), and SiO2 as gate dielectric and regioregular poly(3‐octylthiophene) as organic semiconductor have been measured in situ with reflection or transmission configurations by the FT‐IR difference‐spectrum method. The observed bands have been attributed to the carriers injected into the polymer layers under the application of minus gate bias. The wavenumber of the band around 1300 cm−1 depends on the gate voltage, indicating that the structure of the carriers depends on the carrier concentration. There exist upper limits in the concentrations of the injected carriers. In situ infrared absorption measurements provide the information about the injected carriers, which affect the properties and the functions of polymer field‐effect devices.
Synthesis and characterization of conjugated polymers and their blends for optoelectronic applications
Authors: Economopoulos S.P. , Govaris G.K. , Chochos C.L. , Tzanetos N.P. , Andreopoulou A.K. , Kallitsis J.K. , Yianoulis P. , Gregoriou V.G. 
Published: January 2004

AbstractVarious polymeric blends of hole transporting materials, (such as MEH‐PPV and P3HT) and electron transporting materials (such as poly(phenyl‐vinyl‐quinoline) and poly[2‐(4‐methacryloxyphenyl)‐5‐phenyl)‐1,3,4‐oxadiazole]) have been prepared and investigated. Moreover a soluble, main chain oxadiazole bearing polyether has been synthesized, aiming towards an efficient electron transporting polymeric material which was also used for blend preparation together with P3HT. A deeper investigation into their spectroscopic characteristics using, primarily, FT‐IR spectroscopy, but also UV‐Vis spectroscopy has been conducted. The surface morphology of these blends was investigated using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) in an attempt to gather information for their solid state properties and morphologies. Finally, DSC measurements provided additional insight into the thermal behaviour of these materials.
Infrared spectroscopy studies of structure and orientation in clay‐reinforced polyamide‐6 nanocomposites
Authors: Cole Kenneth C. , Denault Johanne , Bureau Martin N. 
Published: January 2004

AbstractInfrared (IR) spectroscopy was used to study the surface (by means of external reflection) and the bulk (by means of transmission measurements on microtomed slices) of specimens obtained by injection moulding of a commercial polyamide‐6 clay‐based nanocomposite material (NCH = nylon clay hybrid) at different mould temperatures and with different part geometries. Comparisons were made with equivalent non‐reinforced polymer (PA‐6). For the PA‐6, the mould temperature influences the crystalline structure, with the γ phase predominating at 50°C and the α phase at 80°C. However, in the NCH material the ( phase is favoured, even at 80°C. In all cases the crystallinity increases on going from the surface to the core. The polymer chains are oriented in the flow direction, and the orientation is higher for parts with more elongated shapes. It does not vary greatly across the part thickness, except for a thin surface layer, where it is significantly higher. Both at the surface and in the bulk, the crystalline phase orientation is higher for the NCH than for the PA‐6.
Application of vibrational spectroscopy for the analysis of polymer composites
Authors: Bokobza Liliane 
Published: January 2004

AbstractVarious examples of filled elastomeric networks will illustrate the potential of Fourier‐transform infrared spectroscopy for a better understanding of the properties of elastomeric composite materials which are two‐phase materials. The addition of an inorganic component to polymers leads to improvements in various physical and mechanical properties. These improvements are the result of a complex interplay between the properties of the individual constituent phases : the polymer, the filler and the interfacial region. Infrared spectroscopy has been used to characterize the interface in the isotropic state and also under uniaxial extension.
Polarized FT‐IR photoacoustic spectroscopy on polymer fibers
Authors: Eichhorn Klaus‐Jochen , Adam Gudrun 
Published: January 2004

AbstractThe orientation of macromolecular chains in two melt‐spun polymer fibers (segmented polyurethane elastomer and melt‐modified polyolefine fibers) was studied by photoacoustic spectroscopy (PAS) with polarized light in the mid‐infrared range. The PAS orientation functions calculated from the photoacoustic signal intensities of orientation sensitive bands describe the orientation of the different chain segments with respect to the fiber axis. Thus, the orientation of hard and soft segments in the unstressed polyurethane fiber is different and both are similiar to that of the corresponding injection molded bars. With increased spinning velocity an improved orientation of the polyolefine chains along the fiber axis, but only in the amorphous regions of the polymer, were detected.Only a slight reduction of orientation was measured as a result of the subsequent chemical crosslinking in the polyolefines.
Diblock copolymer adsorption from the aqueous micellar phase to solid surfaces: real time monitoring by ATR spectroscopy in the mid‐infrared
Authors: Keskini I. , Gionis V. , Chryssikos G.D. , Hiotelis I. , Toprakcioglu C. , Stavrouli N. , Tsitsilianis C. 
Published: January 2004

AbstractAttenuated Total Reflectance (ATR) in the mid‐infrared is employed to monitor the adsorption of poly(tert‐butyl styrene ‐ b ‐ styrene sulfonate), PtBS‐PSS, copolymers with a small hydrophobic head as well as of an analogous poly(styrene sulfonate), PSS, homopolymer on germanium and Au‐plated germanium surfaces from aqueous NaCl solutions. The surface density of the adsorbed polyelectrolyte is monitored via the growth of characteristic infrared absorptions of the sulfonated ring at 1036‐ and 1008 cm−1 in the 2nd derivative mode. These probe bands do not exhibit shifts or changes in bandshape over very prolongued adsorption experiments. Pronounced differences in the kinetics of adsorption are observed between the PSS homopolymer and the PtBS‐PSS copolymers in agreement to previous investigations by phase‐modulated ellipsometry on similar systems. Adsorption of the diblocks above the critical micelle concentration is found to involve a sequence of diffusion, micellar relaxation and brush‐limited processes.
NMR study of water bound to soft segments in thermoplastic elastomers
Authors: Horstmann Martin , Urbani Marcus , Veeman Wiebren S. 
Published: January 2004

AbstractThe interaction between water absorbed in four hard‐soft segment block‐copolymers and the polymer chains is investigated by pulsed field gradient echo NMR spectroscopy and Nuclear Overhauser NMR spectroscopy. The results show, depending on the structure and mass fraction of the soft segments, a strong interaction between water and the soft segments. Most likely this is due to a hydrogen bond between water and the ether groups. The self‐diffusion of water has been determined and is described as a jumping process between the ether sites with a residence time t and a time between sites t. It is found that the residence time is of the order of a few ns and also that the ratio t/τ decreases with increasing soft segment rigidity.
Role of hydration in the phase transition of polypeptides investigated by NMR and Raman spectroscopy
Authors: Dybal Jiří , Schmidt Pavel , Kříž Jaroslav , Kurková Dana , Rodríguez‐Cabello José Carlos , Alonso Matilde 
Published: January 2004

AbstractNMR, Raman spectroscopy and ab initio quantum‐chemical calculations have been employed to investigate the role of the hydration water in the inverse temperature transition of elastin‐derived biopolymers represented by poly(Gly‐Val‐Gly‐Val‐Pro) and poly(Ala‐Val‐Gly‐Val‐Pro). Temperature and concentration dependences of the Raman spectra measured for water solutions of polymers and of a low‐molecular‐weight model have been correlated with the vibrational frequencies calculated at the DFT (B3LYP) and MP2 levels for the peptide segment surrounded by a growing number of water molecules. The results indicate strong hydration before the transition that, in addition to water hydrogen‐bonded to amide groups, includes hydrophobic hydration of non‐polar groups by a dynamic cluster of several water molecules. According to 1H longitudinal and transverse relaxation of HOD signals in D2O solutions, the number of water molecules motionally correlated with the polymer is about 4 per one amino acid residue.
On‐line monitoring of the acrylate conversion in UV photopolymerization by near‐infrared reflection spectroscopy
Authors: Scherzer Tom , Mehnert Reiner , Lucht Hartmut 
Published: January 2004

AbstractNear‐infrared (NIR) reflection spectroscopy was used to determine the conversion in acrylate coatings after UV photopolymerization in order to test it as a method for process control in UV curing. A probe head was developed which is adapted to the specific requirements of UV curing and which is linked to a photodiode array spectrometer by an optical fiber. Reflection spectra from thin acrylate layers which were taken in intervals down to the millisecond range have shown an excellent signal‐to noise ratio. Quantitative conversion data show good correlation with results from independent reference methods (FTIR, HPLC). Following thesebasic investigations, it was demonstrated that NIR reflection spectroscopy can be used for on‐line monitoring of the acrylate conversion in thin coatings. Some examples of such investigations in pilot scale are presented.
Spectroscopic imaging techniques for characterization of polymer morphologies: a combination of infrared and electron microscopy
Authors: Gupper Andreas , Wilhelm Peter , Kothleitner G. , Eichhorn K.‐J. , Pompe G. 
Published: January 2004

AbstractThe morphological characterization of polymer blends consisting of polyamide and poly(tetrafluoroethylene) using FT‐IR spectroscopy and electron microscopy is described. To enhance the lateral resolution ‐ one of the main limits in infrared spectroscopy ‐ a combination with scanning electron microscopy and analytical electron microscopic methods of a transmission electron microscope was made. The possibilities of electron energy loss spectroscopy and energy filtered transmission electron microscopy (EFTEM) in the area of polymer characterization are outlined.
PM‐IRRAS spectroscopy for the characterization of polymer nanofilms: chains conformation, anisotropy and crystallinity
Authors: Elzein T. , Bistac S. , Brogly M. , Schultz J. 
Published: January 2004

AbstractThis paper is focused on the use of the Polarization‐Modulation Infrared Reflection‐Absorption Spectroscopy (PM‐IRRAS) for studying thin polymer films at interfaces. When forming a polymer film on a metallic substrate, for instance by spin‐coating, the characterization of the polymeric layer becomes very difficult given the small amount of matter deposited and also because of the contact with the metal. Among the techniques well adapted to surface and interface analyses, the PM‐IRRAS spectroscopy represents an excellent tool to probe ultra‐thin films.Different systems have been selected in this study such as polyamides (PA) and ethylene‐co‐vinyl acetate (EVA) nanofilms spin‐coated onto chemically controlled surfaces (i.e. thiol self‐assembled monloayers grafted onto gold coated glass slides). PM‐IRRAS spectroscopy allowed us to characterize the polymer anisotropy (chains orientation and conformation), to suggest a model for chain organization at the polymer/substrate interface, and to calculate the orientation angles. Moreover, we were able to determine, by using PM‐IRRAS, the degree of crystallinity of PA and EVA films of nanometric dimensions without any calibration procedure needed by other techniques.
On the use of vibrational spectroscopy to characterize the structure and aroma barrier of food packaging polymers
Authors: Lagarón J.M. , Cava D. , Giménez E. , Hernandez‐Muñoz P. , Catala R. , Gavara R. 
Published: January 2004

AbstractHigh barrier polymers are of increasing interest and use in nowadays food packaging applications. The reason for that is packaging being more often regarded as a very efficient and convenient means of preserving foodstuffs from deterioration during products handling, transport and shelf‐life. This study reports on some novel morphological characterization aspects by means of vibrational spectroscopy of one of the most widely used families of high gas and aroma barrier materials in commercial food packaging, i.e. the ethylene‐vinyl alcohol copolymers (EVOH). Nevertheless, and as a result of the highly hydrophobic character of the EVOH resins, it is usually low density polyethylene (LDPE) the high water barrier material that is put in direct contact with foods. A description of a simple methodology, yet effective, based on FT‐IR to determine diffusion coefficients of aroma components in LDPE is also presented.
Nanomechanical and optical studies on polymeric membranes
Authors: Charitidis C. , Gioti M. , Logothetidis S. 
Published: January 2004

AbstractThe nanomechanical properties of poly(ethylene terephthalate) (PET) membranes, were examined in light of nanoindentation experiments under conditions of maximum contact load in the range of 0.5‐12 m?. Spectroscopic Ellipsometry (SE) from 1.5 to 6.5 ev (Vis‐FUV range) was also applied to probe the dielectric function (ϵ(ω) of the industrially supplied membranes, as well as their geometrical structure. Mechanical stretching (uniaxial or biaxial) procedures are usually applied for the elongation of the polymeric membranes, their thickness reduction and enhancement of their mechanical and optical performance, causing a preferable orientation of the macromolecules close to the surface. Nanoindentation and se testing have revealed the existence of a two‐layer geometrical structure of the pet membranes, consisting of a thick amorphous pet layer and a thin crystalline‐like pet overlayer, with increased hardness (elastic modulus). The analyses of the experimental dataprovides quantitative information on the formed overlayer, which is ascribed to the processing history of the membrane.
Characterization of the epoxy‐metal interphase: FTIR‐ERAS and spectra calculation for ultra‐thin films
Authors: Wehlack Carsten , Possart Wulff 
Published: January 2004

AbstractThe interphase between polymers and metal substrates can be elucidated by studying ultra‐thin films. In this paper, spin coating films (20 nm ‐ 2 μm) are prepared from a two‐part epoxy adhesive on Au, Al and Cu. After room temperature cure, the chemical structure of the epoxy films is studied by FTIR external reflection absorption spectroscopy (FTIR‐ERAS) and the results are compared with the state in the polymer bulk as measured by attenuated total reflection (FTIR‐ATR). Inevitably, this evaluation of the thin film spectra has to account for the optical situation which is significantly different from bulk measurements. Spectra calculation provides the essential tool for a reasonable comparison between bulk and thin film spectra, thus allowing for a detailed quantitative analysis. Thickness and substrate effects on the interphase can then be separated from the optical situation of the measurement.The results reveal very specific features caused by adhesive interactions and different cure behaviour in the interphase on different metal surfaces.
Dielectric properties and molecular mobility of organic/inorganic polymer composites
Authors: Zois Haralampos , Kanapitsas Athanasios , Pissis Polycarpos , Apekis Lazaros , Lebedev Eugene , Mamunya Yevgen P. 
Published: January 2004

AbstractMicrostructure‐dielectric properties relationship and molecular mobility of organic/inorganic polymer composites (OIPCs), consisting of polyurethane (PU) and sodium silicate (NaSi), were investigated in this work. Broadband dielectric relaxation spectroscopy (DRS) and thermally stimulated depolarization current (TSDC) techniques were employed. Our interest was focused on the study of the glass transition mechanism and conductivity relaxation. The influence of the molecular weight of PU and inorganic phase content on the dielectric properties of the composites was of particular interest. Glass transition temperature shifts to higher temperatures with the addition of NaSi. The overall molecular mobility was found to increase in the composites, compared to the pure PU matrix. The results are more intense for the composites based on the PU with low molecular weight.
Human sperm aneuploidy after exposure to pesticides
Authors: Smith Jena L. , Garry Vincent F. , Rademaker Alfred W. , Martin Renée H. 
Published: January 2004

AbstractThis study examined the effect of paternal environmental exposure to pesticides on the frequency of aneuploidy in human sperm. To determine if the chromosome number in germ cells was altered by paternal exposure, multicolor fluorescence in situ hybridization (FISH) analysis was utilized to measure aneuploidy frequencies in the sperm of 40 men (20 exposed, 20 controls). Samples were coded for “blind analysis” to eliminate scorer bias. Aneuploidy and diploidy frequencies were assessed for chromosomes 13, 21, X, and Y. A minimum of 10,000 sperm was scored per donor per chromosome probe with a total of 809,935 sperm scored. Hybridization efficiency was 99%. There were no significant differences in aneuploidy or diploidy frequencies between exposed and control groups, suggesting that the pesticides did not increase the risk of numerical chromosomal abnormalities in these men. Mol. Reprod. Dev. 67: 353–359, 2004. © 2004 Wiley‐Liss, Inc.
Tektin3 encodes an evolutionarily conserved putative testicular microtubules‐related protein expressed preferentially in male germ cells
Authors: Roy Angshumoy , Yan Wei , Burns Kathleen H. , Matzuk Martin M. 
Published: January 2004

AbstractTektins are microtubule‐associated cytoskeletal proteins that are expressed primarily in the male germ cell‐lineage in centrioles and basal bodies and within ciliary and flagellar doublet microtubules. They are proposed to be important for axonemal architecture and microtubule stability in the sperm tail and in other ciliated and flagellar structures. Using an in silico (electronic database) subtractive approach to identify germ cell‐specific genes in vertebrates, we isolated a new member of the Tektin gene family from mice, Tektin3. Reverse transcriptase‐polymerase chain reaction (RT‐PCR) and Northern blot analyses confirm that Tektin3 encodes a 1.7 kb transcript detectable preferentially in the testes of adult mice. In situ hybridization analysis in the testes revealed Tektin3 mRNA expression exclusively in late pachytene spermatocytes and early round spermatids. The putative TEKTIN3 protein shares 83.5% overall sequence identity with the human ortholog and includes a fully conserved carboxy terminal nonapeptide signature sequence present in all TEKTIN family members. In addition, using database mining, highly conserved TEKTIN3 orthologs were identified in puffer fish (Fugu rubripes) and rats (Rattus norvegicus) which shared 60.9 and 91.4% identity, respectively, with mouse TEKTIN3. The Tekt3 gene maps to murine chromosome 11 in a region that is syntenic to the human 17p12 chromosomal region containing the human TEKTIN3 gene. Our studies demonstrate that TEKTIN3 is a novel evolutionarily conserved male germ cell‐enriched protein and suggest that it might perform important roles in male reproductive development and physiology. Mol. Reprod. Dev. 67: 295–302, 2004. © 2004 Wiley‐Liss, Inc.