bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interfacial adhesion mechanisms in incompatible semicrystalline polymer systems
Authors: Lo Chieh‐Tsung , Laabs Francis C. , Narasimhan Balaji 
Published: June 2004

AbstractThe mechanism of adhesion at semicrystalline polymer interfaces between isotactic polypropylene (iPP) and linear low‐density polyethylene (PE) was studied with transmission electron microscopy (TEM) and an asymmetric‐double‐cantilever‐beam test. From the TEM images, both the interfacial width and the lamellar thickness of the polymers were extracted. During annealing, the interfacial width increased with the annealing temperature, and this indicated the accumulation of amorphous polymers at the interface. The interfacial strength, determined from the critical fracture energy (Gc), also increased with the annealing temperature and reached a maximum above the melting temperatures of iPP and PE, whereas the smallest Gc value was obtained below the melting temperatures of the two materials. A mechanism of interfacial strengthening was proposed accounting for the competition between the interdiffusion of PE and crystallization of iPP. As the annealing temperature increased, the rates of PE diffusion and iPP crystallization increased. Although the crystallization of iPP hindered the interdiffusion of PE, both the interfacial width and the fracture energy increased with the temperature, and this indicated that PE interdiffusion dominated iPP crystallization. Below the critical temperature, the fracture surfaces of both iPP and PE were smooth, and chain pullout dominated the fracture mechanism. Above the critical temperature, iPP crystallization still hindered the interdiffusion, and crazes could be seen on the iPP side. Above the melting temperatures of the two materials, ruptured surfaces could also be seen on the PE side, and crazing was the fracture mechanism. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2667–2679, 2004
Spectroscopic Diagnostics for a DBD Plasma in He/Air and He/N2 Gas Mixtures
Authors: Chiper Alina S. , Aniţa Viorel , Agheorghiesei Catalin , Pohoaţa Valentin , Aniţa Maria , Popa Gheorghe 
Published: June 2004

AbstractSummary: Experimental results obtained by emission spectroscopy on dielectric barrier discharges (DBD) in helium/air and helium/nitrogen gas mixtures are presented. The transition between the glow mode and filamentary mode of the dielectric barrier discharge was determined, and the electrical power transferred to the discharge was calculated. Dependence of the rotational temperature versus nitrogen gas‐flow rate was investigated.Even with a peak power of 2.1 kW and a total energy of 2.3 × 10−4 J per pulse for the FD mode (in comparison to a peak power of 270 W and 5 × 10−5 J per pulse for the GD mode) the line intensity and number of excited species are larger for the GD mode than those of the FD mode.imageEven with a peak power of 2.1 kW and a total energy of 2.3 × 10−4 J per pulse for the FD mode (in comparison to a peak power of 270 W and 5 × 10−5 J per pulse for the GD mode) the line intensity and number of excited species are larger for the GD mode than those of the FD mode.
Influence of Plasma Functionalization of Poly(propylene) with Acrylic Acid on the Nucleation of CaCO3
Authors: Sciarratta Vincenzo , Oehr Christian , Diegelmann Carsten , Löbmann Peer 
Published: June 2004

AbstractSummary:Poly(propylene) surfaces were modified by polymerization of acrylic acid using an RF plasma technique. Whereas a stable and reproducible hydrophilicity is obtained even after short treatment times, the thickness of the deposited layer, and thus the concentration of COOH functional groups per substrate surface area, increases with plasma exposure time. The modified‐poly(propylene) samples were exposed to aqueous solutions supersaturated with respect to CaCO3. Even though the polymer surfaces show a significant affinity for the adsorption of Ca2+ions, the density of nucleation sites for calcite is reduced in comparison to untreated poly(propylene). This result can be explained by the special conditions in porous (“gelatinous”) growth media and high disorder provided by the plasma‐polymerized layers.AFM surface profile of a poly(propylene) surface (*) and film segments of plasma‐polymerized acrylic acid (**).imageAFM surface profile of a poly(propylene) surface (*) and film segments of plasma‐polymerized acrylic acid (**).
Formation of Plasma Polymer Layers with Functional Groups of Different Type and Density at Polymer Surfaces and their Interaction with Al Atoms
Authors: Friedrich Jörg , Kühn Gerhard , Mix Renate , Unger Wolfgang 
Published: June 2004

AbstractSummary:Monotype functionalizations with different types of functional groups (OH, NH2, COOH) on polypropylene and poly(tetrafluoroethylene) surfaces were synthesized using pulsed plasma‐initiated homo‐ or copolymerization of functional group‐carrying monomers. The maximum concentrations of functional groups were 31 OH, 18 NH2or 24 COOH groups per 100 C atoms using allyl alcohol, allylamine or acrylic acid respectively as the monomer. The measured peel strengths of aluminium deposits increased linearly with the concentration of functional groups. Near the maximum concentration of OH (>27 OH/100 C atoms) or at moderate concentrations of COOH groups (>10 COOH/100 C atoms), constant (maximum) peel strengths were measured due to the mechanical collapse of one component in the composite (cohesive failure). Interface failures in Al‐PP composites were found with COOH, NH2and OH groups and cohesive failures were seen when higher concentrations of COOH groups were applied (>10 COOH/100 C atoms).Dependence of Al peel strength in Al‐plasma polymer‐PP systems on the type and density of functional groups in plasma polymer interlayers.imageDependence of Al peel strength in Al‐plasma polymer‐PP systems on the type and density of functional groups in plasma polymer interlayers.
A Review of Plasma‐Surface Interactions During Processing of Polymeric Materials Measured Using the IRIS Technique
Authors: Fisher Ellen R. 
Published: June 2004

AbstractSummary: This work reviews the use of the imaging of radicals interacting with surfaces (IRIS) technique to elucidate chemical mechanisms during plasma modification of polymers. Four systems are examined, NH and NH2 in NH3 plasmas, OH radicals in H2O and O2/NH3 plasmas, OH in SiO2 film deposition systems, and CF2 molecules in a variety of fluorocarbon plasmas. Some of the findings include that NH and NH2 are produced at the surface during NH3 plasma modification of polymers. Their surface interactions are directly connected to each other and are also influenced by other plasma species such as ions. In implantation systems, OH reacts at the surface of polymers, contributing to the creation of hydrophilic polymeric membrane surfaces. In addition, OH surface reactivity is largely controlled by the chemistry of OH and not by other species in the plasma for all three systems studied. In fluoropolymer‐deposition systems, CF2 is scattered from the surface and is strongly influenced by ion bombardment. Most notably, CF2 scatter coefficients can be correlated directly to the percentage of cross‐linking in amorphous fluorocarbon films deposited in a range of plasma systems. Comparisons and contrasts between plasma systems and surface interactions of different species are provided.Spatially resolved two‐ dimensional ICCD images of the LIF signal for NH with a PI substrate rotated into the path of the molecular beam with a laser–surface distance of 3.5 mm.imageSpatially resolved two‐ dimensional ICCD images of the LIF signal for NH with a PI substrate rotated into the path of the molecular beam with a laser–surface distance of 3.5 mm.
Homogeneous and Micro‐Patterned Plasma‐Deposited PEO‐Like Coatings for Biomedical Surfaces
Authors: Sardella Eloisa , Gristina Roberto , Senesi Giorgio S. , d'Agostino Riccardo , Favia Pietro 
Published: June 2004

AbstractSummary: Mixtures of diethyl glycol dimethyl ether vapors and argon were used to feed RF (13.56 MHz) glow discharges and coat polystyrene substrates with poly(ethylene oxide) (PEO)‐like thin films. Different power input values have been used to obtain coatings with different cell‐adhesive properties. Cell‐culture experiments showed a tight correlation between the adhesion/morphology of cultured cell‐lines and the chemical composition of the coatings; the ability of PEO‐like coatings to discourage or promote cell adhesion could thus easily be related to the power delivered to the plasma. Combined deposition processes of different PEO‐like coatings have been performed, with the method of physical masking, to produce surfaces micro‐patterned with cell‐adhesive tracks alternating with cell‐repulsive domains. The micro‐arrangement of different cell‐adhesive domains enabled the patterning of cell cultures and induced the alignment of cells along predefined directions.The adhesion pattern of 3T3 murine fibroblasts on a substrate of PEO10W patterned with a PEO5W coating deposited through a G50p mask after 24 h.imageThe adhesion pattern of 3T3 murine fibroblasts on a substrate of PEO10W patterned with a PEO5W coating deposited through a G50p mask after 24 h.
Relations for the high‐pressure melting temperature of alkali halides based on the diffusional driving force models: NaCl as an example
Authors: Fang Zheng‐Hua 
Published: June 2004

AbstractTwo different diffusional driving force models were presented by Sharma et al. [Indian J. Pure Appl. Phys. 29, 637 (1991)] and Singh [J. Phys. Chem. Solids 63, 1935 (2002)], respectively, for estimating the zero‐pressure melting temperatures of alkali halides. Whether the two models are suitable for the analysis of the high‐pressure melting temperature of alkali halides is examined in this paper. It is shown that, supposing that the product of the thermal expansivity and the isothermal bulk modulus is inversely proportional to the volume along the melting curve, then the two diffusional force models are equivalent and the same relation for the high‐pressure melting temperature of solids may be derived. The reasonableness of this assumption is supported by the analysis and test on NaCl up to 1 Mbar, and is presented here. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal tuning and broadening of the spectral lines of trivalent neodymium in laser crystals
Authors: Chen Xuesheng , Di Bartolo Baldassare , Barnes Norman P. , Walsh Brian M. 
Published: June 2004

AbstractThis work reports a large number of experimental investigations of the effects of temperature on the sharp spectral lines of the trivalent neodymium ion in laser‐type crystals. The available theory that explains these effects in simple luminescence systems is applied to the cases examined when possible. Some general conclusions regarding the thermal effects on the systems examined are presented. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charge‐ordering correlated elastic anomalies in Pr1−xCaxMnO3 perovskite
Authors: Chen C. X. , Qian T. , Zheng R. K. , Wang F. , Li X. G. 
Published: June 2004

AbstractThe temperature dependence of the elastic properties of polycrystalline manganite Pr1−xCaxMnO3 (0.5 ≤ x ≤ 0.85) has been studied systematically by means of ultrasonic measurements. It was found that the longitudinal modulus starts to soften obviously with decreasing temperature from higher temperature to the charge‐ordering transition temperature Tco, and stiffens dramatically just below Tco. The elastic anomalies observed near Tco cannot be explained based on a conventional antiferromagnetic transition. The electron–phonon coupling originating from the Jahn–Teller effect may play an important role in the system. The good fit of the theory to the temperature dependence of the elastic modulus data indicates that the mean‐field theory, which describes the coupling of Jahn–Teller ions to lattice distortions of the Jahn–Teller system, adequately characterizes the behavior. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of the Tl+ center doped in NH4Cl crystals with the CsCl structure
Authors: Kawai Taketoshi , Hashimoto Satoshi 
Published: June 2004

AbstractWe have investigated the optical properties of the Tl+ center doped in NH4Cl single crystals with the CsCl structure. The A, B and C absorption bands due to the cationic transition in the Tl+ ion are observed at 5.22, 6.22 and 6.59 eV at low temperature, respectively. When the A absorption band is photoexcited, the AX luminescence band appears at 4.35 eV, and the AT luminescence band at 3.37 eV. As the temperature increases, the AT band that is dominant at 13 K decreases around 20 and 60 K. On the other hand, the AT band exhibits an increase that compensates the decrease of the AX luminescence intensity. The blue‐shift of the peak energy and the narrowing of the halfwidth with increasing temperature are observed in the temperature ranges from 18 to 25 K for the AX band, and from 25 to 45 K for the AT band. Such complex temperature behaviors of the AX and AT bands are explained on the basis of the thermally activated non‐radiative transitions among four relaxed excited states introduced semiempirically. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fragmentation of multiply charged simple metal clusters in the liquid‐drop stabilized jellium model
Authors: Payami M. 
Published: June 2004

AbstractIn this work, we have used the liquid‐drop model in the context of stabilized jellium model, to study the stability of Z‐ply charged (Z = 1, 2, 3, 4) metal clusters of different species against fragmentation. The liquid drop energy coefficients for each rs value are obtained from fitting of the self‐consistent Kohn‐Sham results for 0 ≤ N ≤ 100. The fission barriers are calculated using the two‐sphere model. Results show that the singly ionized clusters are stable against any spontaneous fragmentation. However, multiply charged clusters of sufficiently small sizes may undergo spontaneous decay via fission processes. The size at which competition between evaporation and fission starts, is predicted in good agreement with experiment for r ≥ 3.99. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability and band gaps of As‐rich and N‐rich GaAsN alloys: Density‐functional supercell calculations
Authors: Jenichen A. , Engler C. 
Published: June 2004

AbstractTotal energies and band gap energies of cubic cells with various arrangements of Ga32As32−nNn (n = 0–8 and n = 28–32 corresponding to 0.0–25.0% N and 12.5–0.0% As) are calculated using the density‐functional supercell method. In the As‐rich limit up to an exchange of 6.2% N isolated N atoms (maximum N distance) are the most stable arrangement and provide the typical reduction of the band gap energy from about 1.5 eV (GaAs) to about 1 eV caused by reduction of the N distance. For higher N content special N distributions are the most stable arrangements. GaNm clusters (m = 2–4) and isolated N atoms are less stable. The band gap remains nearly constant at about 1 eV between 6.2 and 18.8% N. The good agreement between the experimental band gap energies and ones calculated for the most stable arrangements points out that the experimental distribution of the atoms is the thermodynamic equilibrium distribution. In the N‐rich limit, linear As chains in [110] direction or fragments of them are the most stable arrangement. At 9.4% As the band gap disappears. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preisach modeling on the magnetic properties of Sr1−xCaxRuO3
Authors: Hou Deng‐Lu , Xu Jing , Bai Yun , Zhao Jing , Du Guo‐Qiang , Tang Gui‐De , Nie Xiang‐Fu 
Published: June 2004

AbstractThe samples Sr1−xCaxRuO3 (x = 0.0, 0.2, 0.6) have been synthesized by a solid state reaction, and characterized by the zero field cooled (ZFC), field cooled (FC) magnetic moments and the major hysteresis loops. The data have been analyzed within the framework of a generalized Preisach model, which includes thermal fluctuations, critical phenomenon, and temperature dependent distribution of free energy barriers. The model provides an excellent description of the experimental data, and the simulating results are in good agreement with the experiment results. All the ZFC/FC curves at different applied fields and all the major hysteresis loops at different temperatures can be replicated by the model with one set of parameters. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular dynamics simulation of C60 encapsulated in boron nitride nanotubes
Authors: Moon Won Ha , Son Myung Sik , Lee Jun Ha , Hwang Ho Jung 
Published: June 2004

AbstractWe investigate the C60 chain encapsulated in boron nitride (BN) nanotubes using molecular‐dynamics simulation. The most favorable BN nanotubes for encapsulation of C60 molecules are (10, 10) and (17, 0) with energy gains of 3.83 and 3.61 eV per C60 for (n, n) and (n, 0) BN nanotubes, respectively. For the diffusion of a C60 into the tube, the position of atoms of a C60 must be not located above the outer wall of the BN nanotube. The C60 located above the outer wall is quickly absorbed and moves on the surface of the tube. The C60 absorbed on the surface is not spontaneously encapsulated inside the tube, which is due to the energy barrier (0.48 eV) of the edge of the BN nanotube. We also calculate the energy barrier for drawing C60 outside the (10, 10) BN nanotube, which is above 3.92 eV. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical explanation of EPR parameters for Cu2+ ion in TiO2 crystal
Authors: Dong H. N. , Wu S. Y. , Li P. 
Published: June 2004

AbstractThe EPR parameters anisotropic g‐factors gx, gy and gz for Cu2+ ion and hyperfine structure constants Ax, Ay and Az for 63Cu2+ and 65Cu2+ isotopes in rutile (TiO2) crystal are calculated by the method of diagonalizing the full Hamiltonian matrix. The crystal‐field parameters contact with the crystal structure by the aid of the superposition model. The calculated results are in reasonable agreement with the observed values. The results are discussed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Binding energies of excitons in II–VI compound‐semiconductor based quantum well structures
Authors: Senger R. T. , Bajaj K. K. 
Published: June 2004

AbstractWe present a brief description of the calculation of the variation of the binding energy of the heavy‐hole exciton as a function of well width in quantum well structures composed of II–VI compound semiconductors including the effects of exciton–optical phonon interaction as formulated by Pollmann and Büttner [J. Pollmann and H. Büttner, Phys. Rev. B 16, 4480 (1977)], and of particle masses and dielectric mismatches between the well and the barrier layers. We compare the results of our calculations with the available experimental data in ZnSe/MgS, ZnSe/Mg0.15Zn0.85Se, and ZnS/Mg0.19Zn0.81S quantum well structures and find a good agreement. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Harmonic generation by molecules in intense laser and magnetic fields: Orientation effects
Authors: Bandrauk André D. , Lu Huizhong 
Published: June 2004

AbstractWe solve exactly the 3‐D time‐dependent Schrödinger equation (TDSE) for the H molecular ion in combination with intense laser fields and static magnetic fields using a newly developed adaptive grid method. This allows for a study of the control of high‐order harmonic generation (HOHG) in molecules by various orientation of the magnetic and laser fields. In particular, we find regimes of pure‐even‐only and even‐with‐odd harmonic generation spectra for particular field and frequency configurations. Furthermore, HOHG plateaus are found to extend to much larger harmonic order in the presence of magnetic fields, thus offering the possibility of obtaining coherent sources in the X–UV region. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Computing enthalpy–entropy interplay for isomeric fullerenes
Authors: Slanina Z. , Zhao X. , Uhlík F. , Lee S.‐L. , Adamowicz L. 
Published: June 2004

AbstractFullerenes represent unique species in many respects, one of them being one of the highest temperature regions ever used for preparation of chemical species. This very factor automatically substantially enhances the importance of the TS part of the Gibbs function. The essential feature of fullerenic systems has consistently been ignored in computational studies of fullerenes, almost always drawing their conclusions from potential energies or heats of formation. This report demonstrates that the simplified treatment cannot really describe all the features of complex mixtures of isomeric fullerenes. General formulas are surveyed and illustrated on C96—the biggest set of isomeric fullerenes characterized by 13C NMR spectra to date. Computations are carried out for the complete set of 187 isolated‐pentagon‐rule (IPR) isomers of C96, using four semiempirical quantum chemical methods (MNDO, AM1, PM3, and SAM1). Entropy terms are also computed and the relative‐stability problem is entirely treated in terms of the Gibbs function. In overall, the computed data match the observed data reasonably well, although no method can really reproduce the complete ten‐membered observed set. There are however still several aspects to be checked and several possibilities how to improve quality of the computed terms. In principle, such developments are, however, only a question of available computing power. There are, nevertheless, some remaining questions, such as inclusion of anharmonicity effects, contribution from electronic partition function, or even interactions between individual, yet separated motions. This article also discusses a subsequent, more general task of relative stabilities of carbon cages of different dimensions, i.e., relative stabilities of nonisomeric fullerenes. The computational treatment of isomeric mixtures has several interesting features: the results depend on temperature, but not on pressure; only the relative, and not the absolute, values of the heats of formation are needed; and the form of the master equation allows for an ample cancellation of terms in the partition functions. In contrast, for the more general task—relative stabilities of fullerenes of different dimensions—the absolute values of the heats of formation are required, the mentioned cancellations do not operate there, and the scheme is essentially pressure dependent. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Two‐fluid model of superconducting condensates and spin gaps in d‐wave high Tc cuprates from repulsive electronic correlations
Authors: Dunne Lawrence J. , Brändas Erkki J. 
Published: June 2004

AbstractIn this review, a model is presented that accounts in a simple way for the existence of the condensate and spin gap in high Tc superconducting cuprates. The finding of many types of high Tc superconducting cuprates occurred more than a decade ago, but the cause of the superconductivity and electronic structure of such materials remains controversial, and there is no broad agreement as to the origin of pairing or of the spin gap. Our view is that these are correlation effects in a weakly doped electronic system with the appropriate alternant C4v symmetry, as found in the layers of high Tc superconducting cuprates. This two‐fluid model can adequately describe much of the essential behavior of these strange materials. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004