bluuebunny/crossref_metadata_2025 huggingface dataset:
Online measurement of oxygen consumption by goat bone marrow stromal cells in a combined cell‐seeding and proliferation perfusion bioreactor
Authors: Janssen F.W. , Hofland I. , van Oorschot A. , Oostra J. , Peters H. , van Blitterswijk C.A.
Published: July 2006

In an effort to produce clinically useful volumes of tissue engineered bone products, a direct perfusion bioreactor system was developed. Perfusion flow rate, flow direction, and the position of the bioreactor are factors that influenced the amounts and homogeneity of the cells seeded on the scaffold surface. Goat bone marrow stromal cells (GBMSCs) were dynamically seeded and proliferated in this system in relevant volumes (10 cm3) of small‐sized macroporous biphasic calcium phosphate (BCP) scaffolds (2–6 mm). Cell load and cell distribution were shown using Methylene Blue block staining, and 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) staining was used to demonstrate the viability of the cells. Although cells were not distributed homogenously after cell seeding, the scaffolds were covered with a viable, homogeneous cell layer after 25 days of cultivation. The hybrid structures became interconnected, and a dense layer of extracellular matrix formed on and in the scaffolds. Online oxygen measurements during cultivation were correlated with proliferating GBMSCs. It was shown that the oxygen consumption could possibly be used to estimate GBMSC population doubling times during growth in this bioreactor system. On the basis of our results, we conclude that a direct perfusion bioreactor system is capable of seeding and proliferating GBMSCs on BCP ceramic scaffolds that can be monitored online during cultivation. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
A family of balanced incomplete‐block designs with repeated blocks on which general linear groups act
Authors: Bailey R. A. , Cameron Peter J.
Published: August 2006

We give two constructions of a balanced incomplete‐block design discovered by van Lint: the design has parameters (13,39,15,5,5), and has repeated blocks and an automorphism group of order 240. One of these methods can be generalized to produce a large class of designs with the properties of the title. © 2006 Wiley Periodicals, Inc. J Combin Designs
A new upper bound on the cyclic chromatic number
Authors: Borodin O. V. , Broersma H. J. , Glebov A. , van den Heuvel J.
Published: August 2006

A cyclic coloring of a plane graph is a vertex coloring such that vertices incident with the same face have distinct colors. The minimum number of colors in a cyclic coloring of a graph is its cyclic chromatic number χc. Let Δ* be the maximum face degree of a graph. There exist plane graphs with χc = ⌊3/2 Δ*⌋. Ore and Plummer [5] proved that χc ≤ 2, Δ*, which bound was improved to ⌊9/5, Δ*⌋ by Borodin, Sanders, and Zhao [1], and to ⌈5/3,Δ*⌉ by Sanders and Zhao [7]. We introduce a new parameter k*, which is the maximum number of vertices that two faces of a graph can have in common, and prove that χc ≤ max {Δ* + 3,k* + 2, Δ* + 14, 3, k* + 6, 18}, and if Δ* ≥ 4 and k* ≥ 4, then χc ≤ Δ* + 3,k* + 2. © 2006 Wiley Periodicals, Inc. J Graph Theory
Comparing MR image intensity standardization against tissue characterizability of magnetization transfer ratio imaging
Authors: Madabhushi Anant , Udupa Jayaram K. , Moonis Gul
Published: July 2006

Purpose

To evaluate existing methods of standardization by exploiting the well‐known tissue characterizing property of magnetization transfer ratio (MTR) values obtained from MT imaging, and compare the tissue characterizability of standardized T2, proton density (PD), and T1 images against the MTR images.

Materials and Methods

Image intensity standardization is a postprocessing method that was designed to correct for acquisition‐to‐acquisition signal intensity variations (nonstandardness) inherent in magnetic resonance (MR) images. The main idea of this technique is to deform the volume image histogram of each study to match a standard histogram, and to utilize the resulting transformations to map the image intensities into a standard scale. The method has been shown to produce a significant gain in similarity of resulting images and to achieve numeric tissue characterization. In this work we compared PD‐, T2‐, and T1‐weighted images before and after standardization with the corresponding MT images for 10 patient MRI studies of the brain, in terms of the normalized median values on the corresponding image histograms.

Results

No statistically significant difference was observed between the standardized PD‐, T2‐, and T1‐weighted images and the corresponding MTR images. However, a statistically significant difference was found between the pre‐ and poststandardized PD‐, T2‐, and T1‐weighted images, and between the prestandardized PD‐, T2‐, and T1‐weighted images and the corresponding MTR images.

Conclusion

These results suggest that standardized T2, PD, and T1 images and their tissue‐specific intensity signatures may be useful for characterizing disease. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Vascular volume and blood‐brain barrier permeability measured by dynamic contrast enhanced MRI in hippocampus and cerebellum of patients with MCI and normal controls
Authors: Wang Huali , Golob Edward J. , Su Min‐Ying
Published: July 2006

Purpose

To measure the cerebrovascular volume and blood‐brain barrier (BBB) permeability indices in hippocampus and cerebellum of patients with mild cognitive impairment (MCI) using dynamic contrast‐enhanced MRI (DCE‐MRI), and compare to that of normal controls.

Materials and Methods

A total of 11 MCI subjects and 11 healthy elderly controls participated in this prospective study. DCE‐MRI was performed to measure the contrast enhancement kinetics. The early enhancement percentage (at 50 seconds after injection) was defined as the vascular volume index, and the ratio between the four to five–minute enhancement relative to the 50‐second enhancement was defined as the BBB permeability index.

Results

The enhancement kinetics measured from hippocampus of MCI individuals demonstrated a lower magnitude and slower decay than healthy controls, suggesting that they had a smaller vascular volume (significant in the right side; P <0.001) and a higher BBB permeability (not reaching significance level). The vascular volume index was significantly correlated with naming ability (P 0.05).

Conclusion

These results suggest that changes in cerebrovasculature may occur in hippocampus of MCI. DCE‐MRI may provide a noninvasive means to measure the subtle BBB leakage associated with the cerebrovascular pathology commonly found in Alzheimer's disease. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Surface roughness effects on curved pivoted slider bearings with couple stress fluid
Authors: Naduvinamani N. B. , Kashinath Biradar
Published: August 2006

In this paper the effect of surface roughness on the performance of curved pivoted slider bearings is studied. A more general type of surface roughness is mathematically modelled by a stochastic random variable with nonzero mean, variance and skewness. The averaged modified Reynolds type equation is derived on the basis of Stokes microcontinuum theory for couple stress fluids. The closed‐form expressions for the mean pressure, load‐carrying capacity, frictional force and the centre of pressure are obtained. Numerical computations show that the performance of the slider bearing is improved by the use of lubricants with additives (couple stress fluid) as compared to Newtonian lubricants. Further, it is observed that the negatively skewed surface roughness increases the load‐carrying capacity and frictional force and reduces the coefficient of friction, whereas the positively skewed surface roughness on the bearing surface adversely affects the performance of the pivoted slider bearings. Copyright © 2006 John Wiley & Sons, Ltd.
Structure and Dynamic Mechanical Properties of Melt Intercalated Polyamide 6—Montmorillonite Nanocomposites
Authors: Wilkinson Arthur N. , Man Zakaria , Stanford John L. , Matikainen Petri , Clemens Mark L. , Lees Graham C. , Liauw Christopher M.
Published: August 2006

Summary: Polymer‐layered silicate nanocomposites (PLSN), based on polyamide 6 (PA6) and montmorillonite (MMT) modified with an octadecylammonium salt, were produced via melt compounding in a co‐rotating twin‐screw extruder. Wide angle X‐ray diffraction (WAXD) and TEM revealed a PLSN containing 3.3% by weight (wt.‐%) of MMT to exhibit a mixed exfoliated/intercalated morphology, consisting mainly of individual silicate lamellae together with some intercalated stacks, resulting in a mean value of 1.8 lamellae per particle. In contrast, a PLSN containing a higher level of 7.2 wt.‐% MMT exhibited a more ordered intercalated structure, consisting mainly of a distribution of lamellae stacks with a mean value of 3.8 lamellae per particle. The dispersion of MMT in the PLSN generated very large polymer–filler interfacial areas, resulting in significant increase in the volume of constrained PA6 chain segments. Consequently, significant changes in the ratio of α/γ crystallites and in the thermal behaviour of the matrix PA6 were observed during WAXD, DSC and dynamic‐mechanical thermal analysis (DMTA) studies of the PLSN. In particular, damping data from DMTA showed relaxations between Tg and Tm resulting from amorphous polymer chain segments constrained at the polymer–filler interface, indicating the formation of a continuous phase of constrained polymer. In contrast, a PA6 microcomposite formed using unmodified MMT generated much lower polymer–filler interfacial area, with most of the MMT residing within large, poorly wetted aggregates. Consequently, changes to the thermal behaviour of the matrix PA6 were much less significant than those induced in the PLSN.

Shear storage modulus (G′) versus temperature data for the matrix PA6, the 5T and 10T PLSN and the 5P microcomposite.

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Shear storage modulus (G′) versus temperature data for the matrix PA6, the 5T and 10T PLSN and the 5P microcomposite.
Dynamic Monte Carlo Simulation of Atom‐Transfer Radical Polymerization
Authors: Al‐Harthi Mamdouh , Soares João B.P. , Simon Leonardo C.
Published: August 2006

Summary: A dynamic Monte Carlo model was developed to simulate atom‐transfer radical polymerization (ATRP). The algorithm used to describe the polymerization includes activation, deactivation, propagation, chain transfer, and termination by combination and disproportionation reactions. Model probabilities are calculated from polymerization kinetic parameters and reactor conditions. The model was used to predict monomer conversion, average molecular weight, polydispersity and the complete molecular weight distribution at any polymerization time or monomer conversion. The model was validated with experimental results for styrene polymerization and compared with simulation results from a mathematical model that uses population balances and the method of moments. The simulations agree well with experimental and theoretical results reported in the literature. We also investigated the control volume size and number of iterations to reduce computation time while keeping an acceptable noise level in the Monte Carlo results.

Comparison of the chain length distribution of polystyrene made with ATRP and conventional free radical (CFR) polymerization at 50% conversion. The initiator to monomer ratios are 1:100 (ATRP left peak), 1:500 (ATRP right peak), and 1:1000 (CFR).

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Comparison of the chain length distribution of polystyrene made with ATRP and conventional free radical (CFR) polymerization at 50% conversion. The initiator to monomer ratios are 1:100 (ATRP left peak), 1:500 (ATRP right peak), and 1:1000 (CFR).
Evaluation of age‐related labels by senior citizens
Authors: Weijters Bert , Geuens Maggie
Published: July 2006

The age‐related labels third age, elderly, 50+, senior, and retired were evaluated by a 40+ sample. Results of a qualitative and quantitative study showed that the labels third age and elderly evoked predominantly negative associations, and the evaluations of the latter three age‐related labels were generally positive. Cognitive age did not appear to add explanatory power, but group membership did (being retired or not, perceiving oneself as a senior or not). Moreover, a significant interaction effect between group membership and age emerged. When people did not belong or did not perceive themselves to belong to a given age group, the evaluation of the related label became more negative when the respondents approached the age to be eligible for group membership. After becoming or accepting to become part of the group, evaluations of the label increased again. On the basis of these results, an alternative‐stage model is proposed: status irrelevance, status rejection, status acceptance, and status championship. © 2006 Wiley Periodicals, Inc.
Peculiar and typical oligodendrocytes are involved in an uneven myelination pattern during the ontogeny of the lizard visual pathway
Authors: Santos Elena , Yanes Carmen M. , Monzón‐Mayor Maximina , del Mar Romero‐Alemán Maria
Published: July 2006

We studied the myelination of the visual pathway during the ontogeny of the lizard Gallotia galloti using immunohistochemical methods to stain the myelin basic protein (MBP) and proteolipid protein (PLP/DM20), and electron microscopy. The staining pattern for the PLP/DM20 and MBP overlapped during the lizard ontogeny and was first observed at E39 in cell bodies and fibers located in the temporal optic nerve, optic chiasm, middle optic tract, and in the stratum album centrale of the optic tectum (OT). The expression of these proteins extended to the nerve fiber layer (NFL) of the temporal retina and to the outer strata of the OT at E40. From hatching onwards, the labeling became stronger and extended to the entire visual pathway. Our ultrastructural data in postnatal and adult animals revealed the presence of both myelinated and unmyelinated retinal ganglion cell axons in all visual areas, with a tendency for the larger axons to show the thicker myelin sheaths. Moreover, two kinds of oligodendrocytes were described: peculiar oligodendrocytes displaying loose myelin sheaths were only observed in the NFL, whereas typical medium electron‐dense oligodendrocytes displaying compact myelin sheaths were observed in the rest of the visual areas. The weakest expression of the PLP/DM20 in the NFL of the retina appears to be linked to the loose appearance of its myelin sheaths. We conclude that typical and peculiar oligodendrocytes are involved in an uneven myelination process, which follows a temporo‐nasal and rostro‐caudal gradient in the retina and ON, and a ventro‐dorsal gradient in the OT. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Anomalous rheological properties of polyethylene molecular composites
Authors: Yamaguchi Masayuki
Published: July 2006

The effect of molecular weight on the rheological properties in the molten state has been studied for binary blends of high‐density polyethylene obtained by the Zieglar–Natta catalyst and low‐density polyethylene produced in an autoclave process. The blends composed of high‐density polyethylene with a high molecular weight and low‐density polyethylene show a higher drawdown force than the individual pure components, whereas the blends of high‐density polyethylene with a low molecular weight and low‐density polyethylene do not exhibit anomalous behavior. The pronounced drawdown force for the former blend system is attributed to the viscous enhancement in the linear viscoelastic region as well as the nonlinear strain‐hardening behavior in the elongational viscosity. POLYM. ENG. SCI. 46:1284–1291, 2006. © 2006 Society of Plastics Engineers
Three‐dimensional numerical simulation of injection molding filling of optical lens and multiscale geometry using finite element method
Authors: Kim Sang‐Woo , Turng Lih‐Sheng
Published: July 2006

This article presents the development, verification, and validation of three‐dimensional (3‐D) numerical simulation for injection molding filling of 3‐D parts and parts with microsurface features. For purpose of verification and comparison, two numerical models, the mixed model and the equal‐order model, were used to solve the Stokes equations with three different tetrahedral elements (Taylor‐Hood, MINI, and equal‐order). The control volume scheme with tetrahedral finite element mesh was used for tracking advancing melt fronts and the operator splitting method was selected to solve the energy equation. A new, simple memory management procedure was introduced to deal with the large sparse matrix system without using a huge amount of storage space. The numerical simulation was validated for mold filling of a 3‐D optical lens. The numerical simulation agreed very well with the experimental results and was useful in suggesting a better processing condition. As a new application area, a two‐step macro–micro filling approach was adopted for the filling analysis of a part with a micro‐surface feature to handle both macro and micro dimensions while avoiding an excessive number of elements. POLYM. ENG. SCI., 46:1263–1274, 2006. © 2006 Society of Plastics Engineers
Gold coating of polyethylene modified by argon plasma discharge
Authors: Švorčík V. , Kotál V. , Slepička P. , Bláhová O. , Šutta P. , Hnatowicz V.
Published: July 2006

High density polyethylene (PE) was modified by argon plasma discharge and then coated with 50 nm thick gold layer. Surface morphology of as‐modified PE samples and samples coated with Au was studied using atomic force microscopy technique. The surface polarity was characterized by contact angles measured by standard goniometry. A nanoindenter was used to examine the sample's mechanical properties (hardness, elasticity modulus, scratch behavior). The Au layers were characterized using X‐ray diffraction. The plasma modification of PE leads to a strong decrease of the water contact angle, which further depends on the time elapsed after the plasma treatment. Because of plasma‐initiated ablation, a lamellar arrangement of PE polymeric chains becomes apparent on the plasma‐treated samples. The roughness of as‐modified PE decreases as a result of Au deposition. Plasma treatment increases PE microhardness but after subsequent Au deposition, both microhardness and elastic modulus decline. Scratch tests showed that while on Au‐coated pristine PE samples mainly elastic deformation was observed, on plasma‐treated and subsequently Au‐coated samples plastic deformation and mechanical deterioration played a significant role. According to the XRD analysis, Au film deposited on the modified PE should be the most stable. POLYM. ENG. SCI., 46:1326–1332, 2006. © 2006 Society of Plastics Engineers
Supramolecular control of spin‐crossover phenomena in lipophilic Fe(II)‐1,2,4‐triazole complexes
Authors: Kuroiwa Keita , Shibata Tomoko , Sasaki Sono , Ohba Masaaki , Takahara Atsushi , Kunitake Toyoki , Kimizuka Nobuo
Published: July 2006

The spin‐crossover properties of lipophilic, supramolecular Fe(II) complexes bridged by 4‐(3‐dodecyloxy)propyl‐1,2,4‐triazole [Fe(II)(1)3Cl2] were investigated in chloroform and cast films. A purple low‐spin (LS) complex in a powdery form was transformed into pale yellow high‐spin (HS) polymers by dissolution in chloroform. The formation of lipophilic molecular wires in chloroform was observed with transmission electron microscopy. The casting of chloroform solutions onto solid supports produced purple, transparent films (LS state). The cast films exhibited sluggish spin‐crossover (LS ⇋ HS) behavior without thermal hysteresis. On the other hand, the cocasting of equimolar dodecanol or tetradecanol with Fe(II)(1)3Cl2 produced composite films in which alcohol molecules were bound to the complex by ionic hydrogen bonding (ROH···Cl−) and van der Waals interactions. At room temperature, the cast films exhibited regular lamellar structures before and after alcohol doping; this was confirmed by wide‐angle X‐ray diffraction measurements. Interestingly, the Fe(II)(1)3Cl2/CnOH (n = 12 or 14) ternary films showed a reversible abrupt spin crossover accompanied by thermal hysteresis. The observed bistability was related to dynamic structural transformations between lamellar and hexagonal structures. This study provides a novel supramolecular approach to designing spin‐crossover polymer films with controlled thermal bistability. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5192–5202, 2006
Influence of the structure of nanoscopic building blocks on the assembly of micropatterned surfaces
Authors: Germack David S. , Harrisson Simon , Brown Gerald O. , Wooley Karen L.
Published: July 2006

The effect of solution‐state nanoscale structures on the assembly of micropatterns by solvent evaporation was explored with a novel amphiphilic diblock copolymer synthesized by reversible addition–fragmentation chain transfer polymerization. A copolymer of the structure poly(styrene‐alt‐maleic anhydride)75‐b‐isoprene84 was assembled into inverse micelles in toluene, and covalently stabilized in the core by reactive amidation of maleic anhydride residues with 2,2′‐(ethylenedioxy)bis(ethylamine) to create core‐crosslinked nanoparticles (CCNPs) or in the shell by the photoinitiated radical crosslinking reactions of isoprene units to create large crosslinked aggregates (LCAs) of heterogeneous sizes and shapes. Micropatterned films were prepared by the deposition of the diblock copolymer as a solution in acetone and the nanoscale structures (inverse micelle, crosslinked aggregate, and CCNP) as solutions in toluene onto trimethylysilyl chloride treated glass microscope slides under ambient conditions. An analysis by optical microscopy and tapping‐mode atomic force microscopy (AFM) indicated that the nanoscale surface topology could be controlled by the pre‐establishment of the block copolymer phase segregation into well‐defined core–shell nanoassemblies in solution. The most interesting films resulted from the evaporative deposition of inverse micelle and CCNP solutions, which afforded uniform, straplike micropatterns of similar dimensions on the microscale and low surface roughness on the nanoscale (roughness = 4 ± 1 and 6± 1 nm by AFM). © 2006 Wiley Periodicals, Inc. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5218–5228, 2006
Remarkable influence of heat treatment on the structural and superconducting properties of (Y1–xPrx)(BaSr)Cu3O6+z
Authors: Bouallal B. , Nafidi A. , El Abidi A. , Kaaouachi A. El
Published: July 2006

We report here on the preparation, X‐ray diffraction (XRD), Seebeck effect, AC magnetic susceptibility, resistivity measurements and effect of heat treatments in the high Tc superconductor (Y1–x Prx)(BaSr)Cu3O6+z . Each sample was subject to two types of heat treatment: oxygen annealing [O] and argon annealing followed by oxygen annealing [AO]. When x increase, the oxygen content (6+z) of the samples decrease slightly from 6.9 to 6.8 as determined by our iodometry measurements. The orthorhombicity ϵ = (b ‐a)/(b +a) decreases to zero at xt [O] = 0.6 and xt [AO] = 0.75. These indicate a structural phase transition from orthorhombic to tetragonal at xt. Whereas, Tc decrease to zero at xc [O] = 0.7 and xc [A,O] = 0.75. Therefore the [A,O] heat treatment increase xc. Note that ϵ decrease with Tc as foreseen. However, for a given x the [AO] heat treatment makes increase ϵ (Tc). Independently of heat treatment, a increase with x, whereas b decreased to its minimum at xt. For a given x < xt, the heat treatment [AO] makes decrease a and increase. A remarkable correlations were observed between Tc (x) and ϵ (x); and between the variation δTc (x) = Tc [AO]‐Tc [O] and δϵ (x). A combination of several factors such as decrease in the Cu (1)‐apical oxygen distance; cationic order of Prx on the (Sr,Ba) site along c axis, chain oxygen ordering on (O4,O5) sites; increase in p and in‐phase purity for the [AO] samples may qualitatively account for the observed data. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of superconductor Bi‐2223 and its properties after partial oxygen substitution
Authors: Jakes V. , Sykorova D. , Smrckova O. , Vasek P.
Published: July 2006

In the first part of the work two routes of preparation of undoped superconductor Bi‐2223 are compared. The influence of addition of extra PbO is studied as well. The route that leads to higher content of the phase 2223 is then chosen as the appropriate way for preparation of fluorine doped samples of general stoichiometry Bi1.6Pb0.4Sr2Ca2.5Cu3.5Ox–z Fz (z = 0, 0.3, 0.6 and 0.9). These samples are characterized by measuring of their temperature dependence of electrical resistance and critical current density. Their phase composition is determined by XRD. While greater amount of fluorine widenes the superconducting transition and worsenes transport properties, the less doped sample shows increasement of critical current density. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anomalies in magnetoelastic properties of NdFe10V2 alloy
Authors: Alinejad M. R. , Khandan Fadafan H. , Tajabor N. , Fruchart D. , Gignoux D.
Published: July 2006

Magnetostriction and thermal expansion of NdFe10V2 alloy are reported. Experimental isotherms of the magnetostriction show a hill type maximum below 1 T which is more pronounced around 130 K, corresponding to that of spin‐reorientation transition in this alloy. The hills are accompanied by a large zero‐field magnetostrictivity. Hence, observed maxima are attributed to the minimum of magnetocrystalline anisotropy, which is expected at spin‐reorientation temperature. Isotherms of magnetostriction above 50 K saturate at fields of 4 T and above. Studying of the temperature dependence of saturation magnetostriction shows that the experimental results are in good agreement with the prediction of a theory composed by a combination of Callen's single particle model and mean‐field approximation of two particle magnetoelastic interactions. Thermal expansion measurements show that the thermal expansion coefficient is negligible at temperatures below 50 K, then increases with temperature linearly until 230 K, and finally remains constant, around 5×10–6 K–1, near room temperature. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and magnetic properties in the ruthenate Bi2.67Pr0.33Ru3O11
Authors: Zouari S. , Cheikh‐Rouhou A. , Ballou R. , Strobel P.
Published: July 2006

An unreported praseodymium substituted phase of the Bi‐Ru‐O system with formula Bi2.67Pr0.33Ru3O11was prepared. Its crystal structure and magnetic properties were investigated. Pr substituted occurs only on one of the two Bi sites. The magnetism of the compound is dominated by a Pr3+ contribution, that appears to interact antiferromagnetically. A non linear variation of the reciprocal magnetic susceptibility is observed that appears to account for crystal electric field interactions on the Pr3+ ions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of nitrogen insertion on the magnetic and structural properties of Sm2–xGdxFe17 alloys (0 ≤ x ≤ 2)
Authors: Ben Kraiem M. S. , Cheikhrouhou A.
Published: July 2006

The effect of nitrogen insertion on the structural and magnetic properties of Sm2–xGdxFe17Ny compounds (x = 0‐2) has been investigated. X‐ray diffraction patterns at room temperature show that all our synthesized samples are single phase and crystallize in the rhombohedral Th2Zn17‐type structure with very small amount of impurity. Nitrogen insertion leads to a monotonic increase in the unit cell volume, it leads also to an increase in the Curie temperature Tc from 425 K for SmGdFe17 to 760 K for SmGdFe17N3. Moreover, the nitrogen insertion increases the saturated magnetization Ms. Ms increases from 17.9 µB/mole for SmGdFe17 to 32.7 µB/mole for SmGdFe17N3. X‐ray diffraction measurements on magnetically aligned powder samples of Sm2–xGdxFe17Ny reveal a change in the easy magnetization direction from planar before nitrogen insertion to the c‐axis after nitrogen insertion. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Brillouin light scattering in ferromagnetic single layers: hysteresis loop and backward geometry
Authors: Djemia P. , Roussigné Y. , Chérif S.‐M. , Billet D. , Stashkevich A. , Moch P.
Published: July 2006

We present a Brillouin light scattering study of a thick ferromagnetic single layer Ni80Fe20 (44 nm) film, using two different geometrical setup: (i) the so‐called Damon‐Eschbach (DE) geometry where the in‐plane wave vector Q// of the studied spin wave is perpendicular to the external magnetic field H and (ii) the backward geometry (BW) where it is parallel to H (Q// and H lie in the film plane). An in‐plane uniaxial anisotropy that do not exceed 100 Oe is evidenced through the analysis of the variations of DE mode frequency and of the Stokes/anti‐Stokes dissymmetry versus H. The experimental magnetic Brillouin spectra showing the presence of dipolar and exchange standing spin waves are well reproduced for both geometries by our calculations of the scattered intensity using the following magnetic parameters: 4πM = 9400 G; g = 2.13; A = 0.93 10–6 erg.cm–1 for different values of the magnetic field H and of the in‐plane wave vector amplitude Q //. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructure and magnetic behavior of PLD Sr2FeMoO6 thin films
Authors: Di Trolio A. , Larciprete R. , Marotta V. , Testa A. M. , Fiorani D.
Published: July 2006

Sr2FeMoO6 thin films, deposited by Pulsed Laser Deposition at fluence lower than 2 J/cm2, exhibit saturation magnetization and Curie temperature not far from the bulk theoretical values. On the contrary at fluence values higher than 3 J/cm2, a worsening of the ferromagnetic behavior together with an enhancement of the granularity turn up. X‐ray diffraction, magnetization and electrical transport reveal that the saturation magnetization, the Curie temperature and the transport properties of the films are influenced by the chemical composition and by the cation disorder. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of melt convection on microstructure evolution of Nd‐Fe‐B alloys using a forced crucible rotation technique
Authors: Biswas K. , Hermann R. , Filip O. , Acker J. , Gerbeth G. , Priede J.
Published: July 2006

The forced crucible rotation technique has been applied to the solidification of Nd‐Fe‐B alloys. Specially sealed samples were subjected to well‐defined forced rotation during induction heating and solidification. The resulting microstructure of the Nd‐Fe‐B alloys in consideration of melt convection has been investigated using scanning electron probe microscopy. The determination of the α‐Fe volume fraction by measuring the magnetic moment in a vibrating sample magnetometer (VSM) resulted in a distinct reduction of the α‐Fe volume fraction in samples with high crucible rotation frequencies. Furthermore, a new category of experiment has been started where a tailored magnetic field was applied in order to study the microstructure evolution due to an enhancement or suppression of the melt convection by additional alternating magnetic fields. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin polarized transport of iron nitride Fe4N: Analysis using a combination of first principles calculation and model calculation
Authors: Kokado Satoshi , Fujima Nobuhisa , Harigaya Kikuo , Shimizu Hisashi , Sakuma Akimasa
Published: July 2006

To propose a ferromagnet exhibiting a highly spin‐polarized transport, we analyze the spin polarization ratio of the bulk Fe4N (Curie temperature: 761 K), which is focused on by taking into account the fact that a ferromagnetic electrode containing Fe and a light element enhances the tunnel magnetoresistance effect at room temperature. The spin polarization ratio is here defined by P = (σ ↑ – σ ↓)/(σ ↑ + σ ↓), with σ ↑ (σ ↓) being the conductivity at zero temperature of up spin (down spin). The conductivity is obtained using the Kubo formula and the Slater‐Koster tight binding model, where parameters are determined by fitting the band structure of the model to that of the first principles calculation. In the vicinity of the Fermi energy, |P | takes almost 1.0, which is 5.0 times as large as that of bcc‐Fe. It may suggest that Fe4N is very effective as a spin injection electrode. Also, by comparing Fe4N to fcc‐Fe in the ferromagnetic state with the equilibrium lattice constant of Fe4N, it is shown that N plays an important role in increasing |P |. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First principles calculation of electric and magnetic properties of UIn3 intermetalic compound
Authors: Nourbakhsh Z. , Pourghazi A.
Published: July 2006

The electronic and magnetic properties of UIn3 have been calculated in the presence of spin orbit coupling using density functional theory (DFT) by the Wien2k package, and an anti‐ferromagnetic ground state structure has been found for this compound. The spin and orbital magnetic moments has been found for this compound. The spin and orbital magnetic moment have been calculated, and it has been shown the orbital magnetic moment is directed opposite to the spin magnetic moment. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spontaneous polarization in the tetragonal, orthorhombic and rhombohedral phases of KNbO3
Authors: Toumanari Ahmed , El‐frikhe Es‐saïd , Khatib Driss
Published: July 2006

The spontaneous polarization and the refractive indices in the tetragonal, orthorhombic and rhombohedral phases of KNbO3 are discussed quantitatively from the microscopic consideration. The shift of the Nb ion situated at the centre of the lattice is calculated at various temperatures from the mean field approximation model. The spontaneous polarization has been calculated by the dipole‐dipole model using the calculated values of the shift of the Nb ions, the vertical strains and the shearings. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Developing New Cleavage Strategies in a Fluorous Phase Pummerer Cyclative‐Capture Approach for the Synthesis of N‐Heterocycles
Authors: McCormick Rosemary A. , James Karen M. , Willetts Nigel , Procter David J.
Published: August 2006

An efficient, oxidative cleavage of a sulfur linker has been developed for the fluorous phase synthesis of N‐heterocycles. The new cleavage strategy facilitates the synthesis of products containing diverse structural features.
Density matrix calculations of gaseous and adsorbate dynamics in electronically excited molecular systems
Authors: Micha David A.
Published: August 2006

This contribution deals with two approaches for localized phenomena in excited many‐atom systems. The first approach develops a quantum quasi‐classical treatment for the density operator, including all atoms. It is based on a partial Wigner representation and is illustrated with applications to photodissociation of NaI, and to light emission of excited Li interacting with a He cluster. This second application describes the direct dynamics with a time‐dependent electronic density matrix, expanded in a basis set of atomic functions. It shows that such an approach can deal with electronically excited many‐atom systems involving tens of quantum states and hundreds of classical variables. The second approach makes use of the reduced density operator description for a system in a medium. This allows for dissipative dynamics, which can be instantaneous or delayed. An application is presented for femtosecond photodesorption using a Markovian dissipation and construction of the density operator from density amplitudes, for CO/Cu(001). A second application of a reduced density operator has been made to vibrational relaxation of adsorbates, solving integrodifferential equations to compare delayed, instantaneous, and Markovian dissipation. It is concluded that delayed dissipation is needed at short times and that a Markovian treatment is suitable for the interpretation of cross‐sectional measurements that involve long‐term dynamics. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
U‐PVC gelation level assessment, part 2: Optimization of the differential scanning calorimetry technique
Authors: Fillot Louise‐Anne , Hajji Philippe , Gauthier Catherine
Published: July 2006

Differential scanning calorimetry (DSC) is one of the best techniques for assessing PVC gelation level. Thus, it is of great interest to understand and optimize the different aspects of the DSC method. In the present study, DSC experiments were carried out on PVC dryblend samples that were previously heat‐treated at different temperatures. Practical aspects such as sample preparation, heating rate, and ending temperature are described. Then, the obtained DSC patterns are compared and analyzed to clarify the origin of the measured events. The effects of PVC reprocessing on DSC patterns are presented, as well as the effects of heterogeneity issues (i) at the scale of a PVC window profile and (ii) at the scale of a PVC DSC sample. The method used for the determination of the gelation level is then analyzed. The choice of the integration limits that strongly affect the melting enthalpy values is discussed. Different ways of calculating the gelation level, including the conventional definition involving the ratio A/A + B as well as new approaches, are proposed. J. VINYL. ADDIT. TECHNOL. 12:108–114, 2006. © 2006 Society of Plastics Engineers.
Critical assessment of chitotriosidase analysis in the rational laboratory diagnosis of children with Gaucher disease and Niemann–Pick disease type A/B and C
Authors: Ries Markus , Schaefer Ellen , Lührs Till , Mani Latha , Kuhn Jana , Vanier Marie T. , Krummenauer Frank , Gal Andreas , Beck Michael , Mengel Eugen
Published: July 2006

Laboratory diagnosis of lysosomal storage disorders, especially sphingomyelinase deficiency (Niemann–Pick disease type A/B) and Niemann–Pick disease type C (NPC) can be challenging. We therefore aimed to analyse the feasibility of first‐step screening with specific chitotriosidase cut‐off values in children ≤ 10 years of age with visceral organomegaly (hepatomegaly, splenomegaly, or hepatosplenomegaly) in whom a storage disorder was suspected. We conducted a retrospective, cross‐sectional, referral, single‐centre study to assess diagnostic test properties in 106 individuals. Median chitotriosidase activity was 12 655 nmol/h per ml (interquartile range 4693–20982) in Gaucher disease (GD); 780 (465–1298) in SMD (sphingomyelinase deficiency); 925 (319–1215) in NPC and 50 (29–54) in patients with miscellaneous diseases. To restrict the differential diagnosis to GD, SMD or NPC, chitotriosidase activity above 200 nmol/h per ml had a sensitivity of 96%, specificity of 100%, positive predictive value (PPV) of 100%, and negative predictive value (NPV) of 95%. For GD alone, chitotriosidase activity above 4000 nmol/h per ml had a sensitivity of 77%, specificity of 100%, PPV of 100% and NPV of 92%. Of the 44 patients analysed, 4.5% were homozygous and 36.4% heterozygous for chitotriosidase gene duplication. Adjusting for the chitotriosidase genotype, chitotriosidase activities were higher in GD type III than in GD type I. We conclude that, in the above setting, the degree of elevation of chitotriosidase activity can be applied to increase the likelihood of GD, SMD, or NPC and guide the choice of the appropriate confirmatory assay.
Reaction time, inhibition, working memory and ‘delay aversion’ performance: genetic influences and their interpretation
Authors: KUNTSI JONNA , ROGERS HANNAH , SWINARD GREER , BÖRGER NORBERT , MEERE JAAP van der , RIJSDIJK FRUHLING , ASHERSON PHILIP
Published: August 2006

Background. For candidate endophenotypes to be useful for psychiatric genetic research, they first of all need to show significant genetic influences. To address the relative lack of previous data, we set to investigate the extent of genetic and environmental influences on performance in a set of theoretically driven cognitive-experimental tasks in a large twin sample. We further aimed to illustrate how test–retest reliability of the measures affects the estimates.

Method. Four-hundred 7- to 9-year-old twin pairs were assessed individually on tasks measuring reaction time, inhibition, working memory and ‘delay aversion’ performance. Test–retest reliability data on some of the key measures were available from a previous study.

Results. Several key measures of reaction time, inhibition and working-memory performance indicated a moderate degree of genetic influence. Combining data across theoretically related tasks increased the heritability estimates, as illustrated by the heritability estimates of 60% for mean reaction time and 50% for reaction-time variability. Psychometric properties (reliability or ceiling effects) had a substantial influence on the estimates for some measures.

Conclusions. The data support the usefulness of several of the variables for endophenotype studies that aim to link genes to cognitive and motivational processes. Importantly, the data also illustrate specific conditions under which the true extent of genetic influences may be underestimated and hence the usefulness for genetic mapping studies compromised, and suggest ways to address this.
Orphan pensioners and migrating grandparents: the impact of mass migration on older people in rural Albania
Authors: KING RUSSELL , VULLNETARI JULIE
Published: August 2006

Since 1990, Albania has witnessed rural out-migration on a massive scale, both to other countries, chiefly Italy and Greece, and internally to Tirana and other major towns. The scale of this migration has disrupted the multi-generational rural social and kinship systems that, before 1990, displayed strong and coherent family bonds, and simultaneously accommodated paternalistic state directives and were supported by welfare provision for all members of the population. The sudden political, social and rural dislocations that followed the end of the communist regime have made older people particularly vulnerable: many have been left behind by their emigrant children, creating the phenomenon of socially-isolated ‘elderly orphans’. While the migrants' remittances cushion this social isolation, the loss of children and grandchildren through emigration has undermined older people's self-respect and raison d'être in Albanian family life. This paper, based on fieldwork and interviews in regions of heavy out-migration in northern and southern Albania, examines the human impact of emigration on the older people who have been left behind as well as their coping mechanisms, one being to follow their children abroad to care for the grandchildren, enabling the ‘middle generation’, working-age parents both to engage in paid work.
THE SURGICAL MANAGEMENT OF POST PARTUM HAEMORRHAGE
Authors: BALOGUN-LYNCH CHRISTOPHER , WHITELAW NAOMI
Published: July 2006

The historical background of post partum haemorrhage (PPH) dates back to the 17th century. William Smelley published his famous treatise of the theory and practice of midwifery in 1752. His observations sent a clear message to practitioners of the time that haemorrhage in midwifery can be a messenger of death.
Flow-Erleben beim Marathonlauf
Authors: Stoll Oliver , Lau Andreas
Published: August 2006

Zusammenfassung. Ausgehend vom Flow-Konzept Csikszentmihalyis (1992 , 2004 ) und Forschungsberichten zum Flow-Erleben, stellt der Beitrag zwei Studien vor, die Flow-Erfahrungen von Marathonläufern (N = 234) dokumentieren und analysieren. Als Messinstrument diente die Flow-Kurzskala von Rheinberg, Vollmeyer und Engeser (2003 ). Auf der Basis der Selbstberichte der Läufer zum Flow-Erleben (Flow-Generalfaktor) und zu ihrer subjektiven Anforderungs-Fähigkeits-Passung sowie den erfassten Laufzeiten werden in den statistischen Analysen folgende Fragestellungen überprüft: 1.) Stellt die Anforderungs-Fähigkeits-Passung eine Voraussetzung für Flow-Erfahrungen dar? und 2.) Steht Flow im Zusammenhang mit den Laufleistungen? Die Ergebnisse zeigen, dass die Passung nicht zwingend als Voraussetzung für Flow-Erfahrungen angesehen werden muss und ein Flow-Leistungs-Zusammenhang für Marathonläufer der mittleren Leistungsfähigkeit (3 bis 4 Stunden Laufzeit) nicht existiert. Im Resümee werden Schlussfolgerungen für die weitere Flow-Forschung im Sport gezogen.
Selbstkonzept im Sport
Authors: Stiller Jeannine , Alfermann Dorothee
Published: August 2006

Zusammenfassung. Selbstkonzept-Theorien sind in den letzten Jahrzehnten in verschiedenen psychologischen Disziplinen in den Mittelpunkt gerückt, so auch in der Sportpsychologie. Bedeutsame Fragestellungen beziehen sich auf die Struktur und Entwicklung des Selbstkonzepts über die Lebensspanne ( Bracken & Lamprecht, 2003 ; Harter, 1996 , 1999 ; Marsh & Hattie, 1996 ), auf seine Beeinflussbarkeit durch Sport und Bewegung ( Fox, 2001 ), oder auf seinen moderierenden Einfluss, z. B. auf die Athletenidentität ( Brewer, Van Raalte & Linder, 1993 ). Ziel dieses Beitrags soll sein, ausgehend von einer Begriffsklärung zum Selbstkonzept den aktuellen Stand der Forschung wiederzugeben sowie Stärken und Grenzen des Selbstkonzept-Modells von Shavelson, Hubner und Stanton (1976 ) für die Sportpsychologie aufzuzeigen. Zudem wird auf die Struktur- und Entwicklungsaspekte des physischen Selbstkonzepts eingegangen; es werden diagnostische Zugänge vorgestellt sowie der Einfluss von Sport und Bewegung auf das physische Selbstkonzept dargelegt. Für die weitere Forschung wird empfohlen, eine präzisere Definition von Selbstkonzept und theoretisch stringent hergeleitete Messinstrumente zu verwenden sowie vermehrt experimentelle Interventionsstudien durchzuführen. Auch sollte verstärkt das höhere Lebensalter als Untersuchungsgruppe einbezogen werden.
Longitudinal Analysis of Adolescents’ Deviant and Delinquent Behavior
Authors: Reinecke Jost
Published: July 2006

This article presents applications of different growth mixture models considering unobserved heterogeneity within the framework of Mplus ( Muthén & Muthén, 2001a , 2001b , 2004 ). Latent class growth mixture models are discussed under special consideration of count variables that can be incorporated into the mixtures via the Poisson and the zero-inflated Poisson model. Fourwave panel data from a German criminological youth study (Boers et al., 2002) is used for the model analyses. Three classes can be obtained from the data: Adolescents with almost no deviant and delinquent activities, a medium proportion of adolescents with a low increase of delinquency, and a small number with a larger growth starting on a higher level. Considering the zero inflation of the data results in better model fits compared to the Poisson model only. Linear growth specifications are almost sufficient. The conditional application of the mixture models includes gender and educational level of the schools as time-independent predictors that are able to explain a large proportion of the latent class distribution. The stepwise procedure from latent class growth analysis to growth mixture modeling is feasible for longitudinal analyses where individual growth trajectories are heterogenous even when the dependent variable under study cannot be treated as a continuous variable.