bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new equation for predicting electrical conductivity of carbon‐filled polymer composites used for bipolar plates of fuel cells
Authors: Taherian Reza , Hadianfard Mohammad Jaffar , Golikand Ahmad Nozad 
Published: July 2012

AbstractIn this article, a statistical‐thermodynamic formula based on a new approach has been developed to predict electrical conductivity of carbon‐filled composites used for bipolar plate of proton exchange membrane fuel cell. In this model, based on percolation threshold phenomenon, it is assumed that the relationship between electrical conductivity of composite and filler volume fraction follows a sigmoidal equation. Afterwards, the four effective factors on composite conductivity including filler electrical conductivity, filler aspect ratio, wettability, as well as interface contact resistance are replaced upon constant parameters of sigmoidal function. In order to test the model, some single‐filler composites have been manufactured by using the phenolic resin as binder and graphite (G), expanded graphite (EG), and carbon fiber (CF) as fillers. The fitting quality is measured by R‐square, adjusted R‐square, SSE, and RMSE parameters. The results showed that there is a noteworthy agreement between the model and the experimental data. Compared to the other models, this model can be used for more types of fillers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
A surface analysis of polypropylene/clay nanocomposites exposed to electron irradiation
Authors: Asadinezhad Ahmad , Khonakdar Hossein Ali , Jafari Seyed Hassan , Simon Frank , Wagenknecht Udo 
Published: July 2012

AbstractThe effects of electron irradiation in air at various doses on surface chemical composition of nanofilled polypropylene were explored by X‐ray photoelectron spectroscopy. An organically modified nanoclay ingredient along with a functional compatibilizer was employed for this purpose. The nanocomposite formation was confirmed by means of transmission electron microscopy, where in presence of compatibilizer, an exfoliated structure was brought about. Medium irradiation dose was established to be considerably effective in raising surface oxygen content, while at very high electron beam fluence, the ablation (etching) predominated. The optimal electron beam intensity was also found with respect to the extent of the functionalization. Various moieties of ether, ester, and alcohol characteristics were produced after exposure which could act as functional, active precursors being suitable for subsequent functionalization reactions. Furthermore, it could be understood that the electron irradiation spur organoclay migration toward surface layers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Time‐series transcriptional profiling yields new perspectives on susceptibility to murine osteoarthritis
Authors: Poulet Blandine , Ulici Veronica , Stone Timothy C. , Pead Matthew , Gburcik Valentina , Constantinou Eleni , Palmer Donald B. , Beier Frank , Timmons James A. , Pitsillides Andrew A. 
Published: July 2012

AbstractObjectiveChronological age is a powerful epidemiologic risk factor for osteoarthritis (OA), a multifactorial disease that is characterized by articular cartilage (AC) degradation. It is unclear from a molecular perspective how aging interacts with OA to produce this risk to AC integrity. To address this key question, we used in vivo time‐course analysis of OA development and murine interstrain variability in natural susceptibility to OA to examine changes in non–OA‐prone CBA mice versus OA‐prone STR/Ort mice, which develop disease that bears significant histologic resemblance to human OA. Through global transcriptome profiling, we attempted to discover the molecular signature linked with both OA vulnerability and progression.MethodsAffymetrix Mouse Gene 1.0 ST Array profiles were generated from AC samples derived from CBA and STR/Ort mice at 3 different ages, corresponding to the stages prior to, at, and late after the natural onset of OA in the STR/Ort mice.ResultsWe found that the OA in STR/Ort mice exhibited a molecular phenotype resembling human OA, and we pinpointed a central role of NF‐κB signaling and the emergence of an immune‐related signature in OA cartilage over time. We discovered that, strikingly, young healthy AC has a highly expressed skeletal muscle gene expression program, which is switched off during maturation, but is intriguingly retained in AC during OA development in STR/Ort mice.ConclusionThis study is the first to show that AC chondrocytes share a high‐abundance gene‐expression program with skeletal muscle. We show that failure to switch this program off, as well as the restoration of this program, is associated with inappropriate expression of NF‐κB signaling pathways, skeletal muscle–related genes, and induction and/or progression of OA.
In vivo bone‐specific EphB4 overexpression in mice protects both subchondral bone and cartilage during osteoarthritis
Authors: Valverde‐Franco Gladys , Pelletier Jean‐Pierre , Fahmi Hassan , Hum David , Matsuo Koichi , Lussier Bertrand , Kapoor Mohit , Martel‐Pelletier Johanne 
Published: July 2012

AbstractObjectiveIn vitro activation of the receptor EphB4 positively affects human osteoarthritis (OA) articular cell metabolism. However, the specific in vivo role of this ephrin receptor in OA remains unknown. We investigated in mice the in vivo effect of bone‐specific EphB4 overexpression on OA pathophysiology.MethodsMorphometric, morphologic, and radiologic evaluations were performed on postnatal day 5 (P5) mice and on 10‐week‐old mice. Knee OA was induced surgically by destabilization of the medial meniscus (DMM) in 10‐week‐old male EphB4 homozygous transgenic (EphB4‐Tg) and wild‐type (WT) mice. Medial compartment evaluations of cartilage were performed using histology and immunohistochemistry, and evaluations of subchondral bone using histomorphometry, osteoclast staining, and micro–computed tomography.ResultsThere was no obvious phenotype difference in skeletal development between EphB4‐Tg mice and WT mice at P5 or at 10 weeks. At 8 and 12 weeks post‐DMM, the EphB4‐Tg mice demonstrated significantly less cartilage alteration in the medial tibial plateau and the femoral condyle than did the WT mice. This was associated with a significant reduction of aggrecan and type II collagen degradation products, type X collagen, and collagen fibril disorganization in the operated EphB4‐Tg mice. The medial tibial subchondral bone demonstrated a significant reduction in sclerosis, bone volume, trabecular thickness, and number of tartrate‐resistant acid phosphatase–positive osteoclasts at both times assessed post‐DMM in the EphB4‐Tg mice than in the WT mice.ConclusionThis is the first in vivo evidence that bone‐specific EphB4 overexpression exerts a protective effect on OA joint structural changes. The findings of this study stress the in vivo importance of subchondral bone biology in cartilage integrity.
Mechanisms of bone fragility in a mouse model of glucocorticoid‐treated rheumatoid arthritis: Implications for insufficiency fracture risk
Authors: Takahata Masahiko , Maher Jason R. , Juneja Subhash C. , Inzana Jason , Xing Lianping , Schwarz Edward M. , Berger Andrew J. , Awad Hani A. 
Published: July 2012

AbstractObjectiveGlucocorticoid (GC) therapy is associated with increased risk of fracture in patients with rheumatoid arthritis (RA). To elucidate the cause of this increased risk, we examined the effects of chronic erosive inflammatory arthritis and GC treatment on bone quality, structure, and biomechanical properties in a murine model.MethodsMice with established arthritis and expressing human tumor necrosis factor α (TNFα) transgene (Tg) and their wild‐type (WT) littermates were continually treated with GC (prednisolone 5 mg/kg/day via subcutaneous controlled‐release pellet) or placebo for 14, 28, or 42 days. Microstructure, biomechanical properties, chemical composition, and morphology of the tibiae and lumbar vertebral bodies were assessed by micro–computed tomography, biomechanical testing, Raman spectroscopy, and histology, respectively. Serum markers of bone turnover were also determined.ResultsTNF‐Tg and GC treatment additively decreased mechanical strength and stiffness in both the tibiae and the vertebral bodies. GC treatment in the TNF‐Tg mice increased the ductility of tibiae under torsional loading. These changes were associated with significant alterations in the biochemical and structural composition of the mineral and organic components of the bone matrix, a decrease in osteoblast activity and bone formation, and an increase in osteoclast activity.ConclusionOur findings indicate that the concomitant decrease in bone strength and increase in bone ductility associated with chronic inflammation and GC therapy, coupled with the significant changes in the bone quality and structure, may increase the susceptibility of the bone to failure under low‐energy loading. This may explain the mechanism of symptomatic insufficiency fractures in patients with RA receiving GC therapy who do not have radiographic manifestations of fracture.
Optical Spectra of Hexahalogeno‐Antimony (III) Complex Compounds
Authors: Schmidtke Hans‐Herbert , Krause Barbara , Schönherr Thomas 
Published: July 2012

AbstractComplex compounds of SbX3−6 (X = Cl, Br) with alkylammonium counter ions were prepared and optically investigated by recording absorption spectra from materials in KBr discs, thin films and in solution. Emission spectra are measured from powder samples. The spectra exhibit the band patterns and temperature dependences known from other s2 systems which are characterized by Jahn‐Teller effects in the excited states of threefold orbital degeneracy. For the first time also the B band has been observed to be split in the absorption spectrum of an Sb(III) system which is attributed to vibronic coupling of the Γ−5(3P2) level to the τ2g Jahn‐Teller active mode.
Phase Behavior of Ionic Microemulsions
Authors: Lekkerkerker H. N. W. , Kegel W. K. , Overbeek J. Th. G. 
Published: July 2012

AbstractNon‐polar oils and water can form thermodynamically stable quasi‐homogeneous (colloidal) mixtures (called microemulsions) in the presence of relatively large amounts (several %) of ionic surfactants. If the surfactant contains a single hydrocarbon chain (e.g. Sodium Dodecyl Sulphate) the presence of a non‐ionic cosurfactant (e.g. hexanol) and electrolyte (concentration of the order 0.1 M) is essential. With a double chain surfactant (e.g. Aerosol OT) the cosurfactant can be missed. At increasing concentrations of electrolyte and/or cosurfactant the nature of the microemulsion changes from droplets of oil in water via a presumably bicontinuous pattern to droplets of water in oil. It should be obvious that thermodynamic stability requires the interfacial tension between water and oil to be low (order of 0.01‐0.1 mN m−1) so that the dispersion entropy can offset the interfacial free energy. At these low interfacial tensions the influence of curvature on the interfacial tensions becomes important. It turns out that a given amount of surfactant (and co‐surfactant) can only disperse a limited amount of oil in water or of water in oil or of water and oil into one another and therefore a microemulsion may be in equilibrium with non colloidal oil and/or water phases. In the bicontinuous microemulsion oil and water may have a geometrically irregular interface or they may form lamellae of more or less constant thickness or other structures, such as a “molten cubic phase”. These equilibria lead to very interesting, but rather complicated phase diagrams. It will be discussed by what mechanisms the various components of the mixture influence the interfacial tension and promote the stability of the microemulsion and how this depends on the chemical nature of the components.
Morphological Thermodynamics of Microemulsions
Authors: Wagner Herbert 
Published: July 2012

AbstractThis note drafts a model where the thermodynamics of microemulsions is manifestly related with global morphological features of surfactant monolayers. The thermostatistics is governed by the competition between the surface tension of the monolayers and a topological energy encoded in the Euler characteristic. The model phase diagrams reproduce typical features of real microemulsions.
Optical Methods for Studying Microemulsions and Microemulsion Interfaces
Authors: Langevin D. 
Published: July 2012

AbstractOptical methods are particularly interesting to study colloidal systems. They are extremely varied, they can probe both bulk and surface properties and they introduce little perturbation. One of the best known methods is light scattering. When applied to bulk samples, the method can give information about dispersion sizes, interactions between dispersed objects, type of organization in the case of ordered dispersions, critical behaviour, etc. Less widely known is the surface light scattering method, which leads to the determination of surface tension, and in some cases, surface elasticity and viscosity. Many other methods are available: Forced Rayleigh scattering and Florescence recovery after fringe pattern photobleaching (FRAP) probe self‐diffusion, Electrical birefringence is sensitive to non‐spherical objects or to aggregates and to their lifetimes. Surface methods such as Reflectivity or Ellipsometry are sensitive to the surface layer composition and to its roughness. More elaborated methods such as Second Harmonic generation or Infrared and Raman spectroscopy at surfaces give more detailed information about interfacial structures, but have not yet been applied much to microemulsion systems. In the following, we will describe the first methods and illustrate their potential applications for microemulsions with various experimental results obtained in our laboratory.
Kinetics and multilayering in the adsorption of polyelectrolytes to a charged surface
Authors: Schlenoff Joseph B. , Li Ming 
Published: July 2012

AbstractThe kinetics of radiolabeled poly(styrene sulfonate) adsorbing at a positively‐charged surface were determined using a surface‐charged plastic scintillator as substrate. In situ measurements indicate diffusion‐limited adsorption with the final adsorbance dependent on the solution concentration of polyelectrolyte. An absence of self‐exchange of unlabeled for labeled polymer suggests a thermodynamically irreversible process, at least for highly‐charged polymers on highly‐charged surfaces in the weak screening limit. Charge compensation of sulfonate was determined by displacement of labeled calcium (45Ca2+) probe ions. Compensation is complete for surface sites and only partial for interior sulfonates. The use of radiometric techniques facilitates studies of polyelectrolyte multilayer formation.
The influence of ionic charges on the structural and dynamical behavior of O/W microemulsion droplets
Authors: Gorski N. , Gradzielski M. , Hoffmann H. 
Published: July 2012

AbstractAn O/W microemulsion system has been investigated where the droplet size can be controlled via the concentration of cosurfactant (1‐hexanol). In that system the charge density of the droplets was varied by substitution of the original nonionic surfactant by a cationic surfactant. SANS measurements showed that the droplet radii are unaffected by the charging process, whereas the polydispersity decreases with increasing charge density. SANS and also static light scattering experiments are well described by a simple electrostatic model, which renders this droplet system a good model system. In contrast to that the diffusion coefficient shows a somewhat more complicated behavior. It increases strongly with rising ionic content but goes through a maximum around 3 mol% ionic surfactant and then decreases again. The magnitude of the increase and the position of the maximum are well described by theory, whereas the steepness of the decrease at still higher ionic surfactant content is not accounted for.
Photochemistry in porous materials III: Oxygen quenching of the fluorescence of fluoranthene adsorbed on silicagel of uniform pore size
Authors: Springob C. , von Bünau G. , Wolff T. , Schüth F. 
Published: July 2012

AbstractThe luminescence quenching reaction of fluoranthene by molecular oxygen on MCM‐41, a silicagel of uniform pore size, was studied at room temperature by time‐resolved and steady‐state fluorescence spectroscopy. The quenching reaction is well described by the Langmuir‐Hinshelwood‐(LH)‐model. By applying this model to the experimental results rate constants of the quenching reaction, equilibrium constants of oxygen adsorption, rate constants of oxygen desorption and heats of oxygen adsorption were derived.
Thermal unimolecular decomposition of acetic anhydride in the gas phase
Authors: Akao M. , Saito K. , Okada K. , Takahashi O. , Tabayashi K. 
Published: July 2012

AbstractThe thermal decomposition of acetic anhydride has been investigated behind incident and reflected shock waves at temperatures between 750 K and 980 K. The decomposition was monitored by vacuum‐UV absorption and IR emission. We confirmed that the decomposition proceeds to yield ketene and acetic acid with the first order reaction rate. Arrhenius parameters, for the rate constant were log(A/s−1) = 11.8 and Ea = 138 kJ/mol in our temperature region. Since the rate data evaluated in this work coincided with an extrapolation of the previous data, an Arrhenius expression which covers a wide temperature range from 470 K to 980 K was re‐evaluated as k = 1012.2 exp (−145 kJ/mol−1/RT) s−1An ab initio MO calculation showed that the most probable reaction path is the concerted elimination through a 6‐center transition state. The potential barrier height for this path was evaluated to be 156 kJ/mol at the MP4(SDTQ) level.
Dynamics of strong and fragile glass formers and a scaling procedure for the temperature dependence of the viscosity
Authors: Rössler E. , Kudlik A. , Hess K.‐U. , Dingwell D. B. , Sokolov A. P. , Novikov V. N. 
Published: July 2012

AbstractWe review results from Raman scattering experiments on different types of glass formers which have been analysed in order to describe the fast relaxations occurring above Tg. Both fragile and strong glass formers exhibit similar dynamics which can be qualitatively reproduced by mode coupling theory (MCT). In particular, a crossover temperature Tc can be extracted where Tc>Tg. Quantitatively, deviations from the MCT predictions are larger, the stronger the glass former is. One reason for the deviations stems from low‐frequency vibrations which also contribute to the dynamic structure factor and which are small in fragile but large in strong liquids. A change of dynamics at T>Tg is also indicated in simple liquids by the emergence of a slow secondary relaxation process and by the break‐down of rotational‐translational coupling. Furthermore, a viscosity analysis is performed by introducing a crossover temperature Tx which marks the boundary between two dynamical regimes. For all glass formers a master curve is obtained at T<Tx. Tx is found to be close to Tc. Applying this scaling procedure to aluminosilicate melts, systematic trends as a function of the composition are revealed.
Correlation Between Surface Non‐Radiative Recombination and Current Oscillation at p‐Si(100) During Electropolishing in Fluoride Solution
Authors: Rappich J. , Yu. Timoshenko V. , Dittrich Th. 
Published: July 2012

AbstractThe electropolishing of p‐Si(100) in aqueous NH4F solution is investigated in‐situ by photoluminescence (PL) with short N2‐laser pulses. The PL signal increases with potential and reaches a maximum when current oscillations occur. The PL signal oscillates with the same period but anticorrelated to the current. The thin anodic oxides are removed at a low cathodic potential. The respective peak of the current transient is used to monitor the relative changes of the anodic oxides. The results are discussed from the point of view of non‐radiative defect generation during electropolishing, which is controlled by the potential and the rate of oxidation.
Static light scattering and small angle neutron scattering experiments with a nonionic surfactant/deuterium oxide system approaching the liquid/liquid coexistence curve: Study of the system C12E5/D2O
Authors: Lesemann M. , Martin A. , Belkoura L. , Woermann D. , Hoinkis E. 
Published: July 2012

AbstractStatic light scattering experiments with C12E5/D2O mixtures are carried out in the “large aggregate region” of the phase diagram of the system adjacent to the lower part of the binodal curve. They demonstrate the existence of concentration fluctuations with long range correlations. For a mixture of critical composition the correlation length § of the concentration fluctuations diverges approaching the critical temperatures Tc. The critical amplitude §0 has a value of §0 = 1.8 nm which is large compared to that found with nonaggregating binary liquid mixtures with a miscibility gap. The experimentally determined values of the critical exponents v and y are consistent with the theoretical expected universal values. For mixtures of noncritical composition § increases approaching the binodal curve and has a finite comparatively large value at the temperature of phase separation Tp. Small angle neutron scattering experiments with a C12E5/D2O mixture of critical composition show that the angular dependence of the scattered intensity becomes only approximately temperature independent approaching Tc (i.e. large values of the scaling variable x = q § (q, absolute value of the scattering vector). This is contrary to expectation. On the basis of the expression approximating the universal correlation scaling function for values of x<20 it is expected that the temperature dependence should vanish. From this findings taking into account also results of dynamic light scattering obtained with the same system (A. Martín et al., J. Phys. Chem. 100, 13762 (1996)) it is hypothesized that in the “large aggregate” region of the phase diagram adjacent to the binodal curve concentration fluctuations with long range correlations and their dynamics contribute to the changes of the size and shape of the micellar structures described in the literature.
Structural and electrochemical investigations of self‐assembled monolayers of azobenzenealkanethiol and ferrocenealkanethiol containing amido linkages
Authors: Yu Hua‐Zhong , Wang Yong‐Qiang , Cai Sheng‐Min , Liu Zhong‐Fan 
Published: July 2012

AbstractNovel amido linkage containing molecules, HS‐CH2CH2NHC(O)‐Ar‐N = N‐Ar (AzoC2) and HS‐CH2CH2NHC(O)‐(η5‐C5H4)Fe(η5‐C5H5)(FcC2), for self‐assembly were synthesized. They spontaneously adsorb onto gold surface and form stable monolayers. These monolayers were thoroughly characterized by using contact angle measurements, grazing‐angle incidence infrared spectroscopy (GA‐FTIR) and cyclic voltammetry (CV). The structure and properties of the monolayers were found to be highly dependent on the functional moieties, ferrocene or azobenzene in their respective SAMs. The AzoC2 monolayer is more closely packed and highly oriented than FcC2 monolayer due to the interchain hydrogen bonding as evidenced by GA‐FTIR data. The FcC2 SAM is relatively loose with a low surface concentration. On the other hand, the electron‐transfer rate constant of AzoC2 SAM is much smaller than that of FcC2 system, although the redox centers are located at the same distance from the electrode surface. In this sense, the spatial inhibition for the proton transportation and structural conformational change in the redox process of azobenzene should be considered as the dominant reason for the low electron transfer rate constant.