bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of ultraviolet photografting technology to acrylamide/polyethylene to improve the interfacial adhesion of polyethylene/unsaturated polyester resin composites
Authors: Chiu Hsien‐Tang , Shong Zhi‐Jian 
Published: November 2008

AbstractThis study was divided into two sections. In the first part, we used ultraviolet (UV) rays in the wavelength range 300–400 nm to remove the hydrogen atom from polyethylene (PE) and worked with a hydrophilic monomer to complete the grafting action. In the second part, we used the best conditions derived from the previous film grafting and applied them to fibers to achieve excellent adhesion for application in composite materials. For the handling process of the PE film, we initially used acrylamide (AM) as the monomer and then added acetone and benzophenone (BP) to form a reactive solution for the advanced photografting process. In general, the optimum concentrations of the monomer solutions obtained from the photografting of PE films were 2 mol/L of AM and 0.2 mol/L of BP. The UV irradiation time was fixed at 30 min. The optimum grafting conditions achieved in the first part of this research were applied in the photografting process for the PE fiber bundles in the second part. The unsaturated polyester (UP) resins were spread over the outer surfaces of the modified fibers. This was done to strengthen and increase the interface between the UP resins and the modified PE fiber. During the curing experiment of the grafted fiber bundles in the resin coatings, the best material quality was obtained under the following conditions: hardener content = 0.85% (relative to the UP resin weight), oven temperature = 80°C, and time frame = 5 h. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Immobilization cyclen copper (II) on merrifield resin: Efficient oxidative cleavage of plasmid DNA
Authors: Li Kun , Zhang Ji , Zhang Zhong‐Wei , Xiang Yong‐Zhe , Lin Hong‐Hui , Yu Xiao‐Qi 
Published: November 2008

AbstractMerrifield resin‐supported cyclen (MRC) was directly prepared by attaching 1, 4, 7, 10‐tetraazacyclododecane (cyclen) to Merrifield resin (MR). Subsequent coordination with Cu(II), Co(II), and Ni(II) gave immobilized cyclen complex MRC‐Cu, MRC‐Co, and MRC‐Ni as “solid artificial enzymes.” These complexes were characterized by elemental analysis, IR spectroscopy, ICP‐AES, and scanning electron microscopy (SEM). Furthermore, the DNA cleavage activities of these complexes were investigated by agarose gel electrophoresis. The results indicated that MRC‐Cu was superior to other solid artificial enzymes, and the cleavage process was carried out via oxidative pathway. Moreover, the solid catalyst MRC‐Cu was very stable and it could be reused at least four times without any loss of catalytic activity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Copolymerization of ethylene and propylene catalyzed by novel magnesium chloride supported, vanadium‐based catalysts
Authors: Jiang Tao , Du Wei , Zhang Li , Song Xianfeng , Zhang Guangyuan , Ning Yingnan 
Published: November 2008

AbstractTwo novel magnesium chloride supported, vanadium‐based Ziegler–Natta catalysts with 9,9‐bis(methoxymethyl)fluorene and di‐i‐butyl phthalate as internal donors were prepared and used in the copolymerization of ethylene and propylene. The catalytic behaviors of these catalysts were investigated and compared with those of traditional magnesium chloride supported, vanadium‐based catalysts without internal donors. Differential scanning calorimetry, gel permeation chromatography, and 13C‐NMR spectroscopy analysis were performed to characterize the melting temperatures, molecular weights, and molecular weight distributions as well as structures and compositions of the products. The copolymerization kinetic results indicated that the novel catalyst with 9,9‐bis(methoxymethyl)fluorene as an internal donor had the highest catalytic activity and optimal kinetic behavior in ethylene–propylene copolymerization with an ethylene/propylene molar ratio of 44/56. Low‐crystallinity and high‐molecular‐weight copolymers were obtained with these novel magnesium chloride supported, vanadium‐based catalysts. The reactivity ratio data indicated that the catalytic systems had a tendency to produce random ethylene–propylene copolymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of poly(vinyl pyrrolidone) concentration and coagulation bath temperature on the morphology, permeability, and thermal stability of asymmetric cellulose acetate membranes
Authors: Saljoughi Ehsan , Amirilargani Mohammad , Mohammadi Toraj 
Published: November 2008

AbstractCellulose acetate (CA) is widely used in membrane processes. In this study, CA (weight‐average molecular weight = 52,000) was mixed with poly(vinyl pyrrolidone) (PVP; weight‐average molecular weight = 15,000) as an additive in 1‐methyl‐2‐pyrrolidone as a solvent. The phase‐inversion method was used for the preparation of flat‐sheet membranes. The effects of PVP concentration and coagulation bath temperature (CBT) on the morphology, pure water permeation flux, and thermal stability of the prepared membranes were studied and are discussed in this article. The solute rejection of the developed CA membranes was quantified with an insulin protein solution. The results showed that an increase in the CBT levels from 0 to 23°C along with an increase in the PVP concentration in the cast film from 0 to 1.5 wt % resulted in an increase in the macrovoid formation in the membrane sublayer, an increase in the pure water flux (PWF), and a decrease in insulin rejection. Further increases in the PVP concentration from 1.5 to 3, 6, and 9 wt % resulted in gradual suppression of the macrovoid formation, a decrease in PWF, and an increase in insulin rejection. Higher PVP concentrations and lower CBT levels also appeared to result in higher glass‐transition temperatures. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Exploring the relationships between work task and search task in information search
Authors: Li Yuelin 
Published: November 2008

AbstractTo provide a basis for making predictions of the characteristics of search task (ST), based on work task (WT), and to explore the nature of WT and ST, this study examines the relationships between WT and ST (inter‐relationships) and the relationships between the different facets of both WT and ST (intra‐relationships), respectively. A faceted classification of task was used to conceptualize work task and search task. Twenty‐four pairs of work tasks and their associated search tasks were collected, by semistructured interviews, and classified based on the classification. The results indicate that work task shapes different facets or sub‐facets of its associated search tasks to different degrees. Several sub‐facets of search task, such as Time (Length), Objective task complexity, and Subjective task complexity, are most strongly affected by work task. The results demonstrate that it is necessary to consider difficulty and complexity as different constructs when investigating their influence on information search behavior. The exploration of intra‐relationships illustrates the difference of work task and search task in their nature. The findings provide empirical evidence to support the view that work task and search task are multi‐faceted variables and their different effects on users' information search behavior should be examined.
How much and where? Private versus public universities' publication patterns in the information systems discipline
Authors: Holsapple Clyde W. , O'Leary Daniel 
Published: November 2008

AbstractIn most disciplines of scholarly endeavor, there are many efforts at ranking research journals. There are two common methods for such efforts. One of these is based on tabulations of opinions offered by persons having some kind of relationship with the discipline. The other is based on analyses of the extent to which a journal's articles have been cited by papers appearing in some selected set of publications. In either case, construction of a journal ranking for a discipline makes no effort to distinguish between private and public universities. That is, data are aggregated from both private and public faculty researchers. It is thus assumed that the resultant ranking is applicable for both kinds of institutions. But, is this assumption reasonable? The answer is very important because these rankings are applied in the evaluation of promotion, tenure, and merit cases of faculty members working in a discipline. Here, we examine this widespread bibliometric assumption through the use of a ranking methodology that is based on the actual publishing behaviors of tenured researchers in a discipline. The method is used to study the behaviors of researchers at leading private universities versus those at leading public universities. Illustrating this approach within the information systems discipline, we find that there are indeed different publication patterns for the private versus public institutions. This finding suggests that journal‐ranking exercises should not ignore private–public distinctions and that care should be taken to avoid evaluation standards that confound private and public rankings of journals.
Total Synthesis of (−)‐Apratoxin A, 34‐Epimer, and Its Oxazoline Analogue
Authors: Numajiri Yoshitaka , Takahashi Takashi , Doi Takayuki 
Published: November 2008

AbstractA concise and convergent total synthesis of the highly cytotoxic marine natural product apratoxin A is accomplished by an 18‐step linear sequence. The high sensitivity of the thiazoline, bearing an adjacent β‐hydroxyl group at the C35‐position, results in the assembly process requiring the inclusion of appropriate protecting groups and the careful optimization of all individual transformations. In the synthesis of 3,7‐dihydroxy‐2,5,8,8‐tetramethylnonanoic acid (Dtena), the three reagent‐controlled asymmetric reactions enables us to introduce four chiral carbon centers in a dihydroxylated fatty acid moiety. Formation of the hindered ester and sterically‐unfavorable N‐methylamide bonds were successfully demonstrated. The thiazoline in apratoxin A was constructed by Tf2O and Ph3PO‐mediated dehydrative cyclization, and final macrocyclization was achieved between N‐methylisoleucine and proline residues. Moreover, an oxazoline analogue and a C34 epimer of apratoxin A have also been elaborated in a similar approach. This synthetic route would enable assembly of other analogues differing in stereocenters of Dtena and their amino acids.
Dynamical mixing of two stellar populations in globular clusters
Authors: Decressin T. , Baumgardt H. , Kroupa P. 
Published: November 2008

AbstractStars in globular clusters (GCs) exhibit a peculiar chemical pattern with strong abundance variations in light elements along with a constant abundance in heavy elements. These abundance anomalies can be explained by a primordial pollution due to a first generation of fast rotating massive stars which released slow winds into the ISM from which a second generation of chemically anomalous stars can be formed. In particular the observed ratio of anomalous and standard stars in clusters can be used to constrain the dynamical evolution of GCs as around 95% of the standard stars need to be lost by the clusters. We show that both residual gas expulsion during the cluster formation and long term evolution are needed to achieve this ratio. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamics of the disks of nearby galaxies
Authors: Fuchs B. 
Published: November 2008

AbstractI describe how the dynamics of galactic disks can be inferred by imaging and spectroscopy. Next I demonstrate that the decomposition of the rotation curves of spiral galaxies into the contributions by the various components of the galaxies is highly degenerate. Constraints on the decomposition can be found by considering implications for the dynamics of the galactic disks. An important diagnostic is the Toomre Q stability parameter which controls the stability of a galactic disk against local Jeans collapse. I also show how the density wave theory of galactic spiral arms can be employed to constrain the mass of a galactic disk. Applying both diagnostics to the example of NGC2985 and discussing also the implied massto‐light ratio I demonstrate that the inner parts of the galaxy, where the optical disk resides, are dominated by baryons. When I apply this method to the disks of low surface brightness galaxies, I find unexpectedly high mass‐to light ratios. These could be explained by population synthesis models which assume a bottom heavy initial mass function similar to the recently proposed ‘integrated galactic initial mass function’. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Massive Black Hole recoil in high resolution hosts
Authors: Guedes J. , Diemand J. , Zemp M. , Kuhlen M. , Madau P. , Mayer L. , Stadel J. 
Published: November 2008

AbstractThe final inspiral and coalescence of a black hole binary can produce highly beamed gravitational wave radiation. To conserve linear momentum, the black hole remnant can recoil with “kick” velocity vkick ≤ 4000 km/s. We present two sets of full N‐body simulations of recoiling massive black holes (MBH) in high‐resolution, non‐axisymmetric potentials. The host to the first set of simulations is the main halo of the Via Lactea I simulation (Diemand et al. 2007). The nature of the resulting orbits is investigated through a numerical model where orbits are integrated assuming an evolving, triaxial NFWpotential, and dynamical friction is calculated directly from the velocity dispersion along the major axes of the main halo of Via Lactea I. By comparing the triaxial case to a spherical model, we find that the wandering time spent by the MBH is significantly increased due to the asphericity of the halo. For kicks larger than 200 km/s, the remnant MBH does not return to the inner 200 pc within 1 Gyr, a timescale an order of magnitude larger than the upper limit of the estimated QSO lifetime. The second set of simulations is run using the outcome of a high‐resolution gas‐rich merger (Mayer et al. 2007) as host potential. In this case, a recoil velocity of 500 km/s cannot remove the MBH from the nuclear region. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Status and future of MUSE
Authors: Harfst S. , Zwart S. Portegies , McMillan S. 
Published: November 2008

AbstractWe present MUSE, a software framework for combining existing computational tools from different astrophysical domains into a single multi‐physics, multi‐scale application. MUSE facilitates the coupling of existing codes written in different languages by providing inter‐language tools and by specifying an interface between each module and the framework that represents a balance between generality and computational efficiency. This approach allows scientists to use combinations of codes to solve highly‐coupled problems without the need to write new codes for other domains or significantly alter their existing codes. MUSE currently incorporates the domains of stellar dynamics, stellar evolution and stellar hydrodynamics for studying generalized stellar systems. We have now reached a “Noah's Ark” milestone, with (at least) two available numerical solvers for each domain. MUSE can treat multi‐scale and multi‐physics systems in which the time‐ and size‐scales are well separated, like simulating the evolution of planetary systems, small stellar associations, dense stellar clusters, galaxies and galactic nuclei. In this paper we describe two examples calculated using MUSE: the merger of two galaxies and an N ‐body simulation with live stellar evolution. In addition, we demonstrate an implementation of MUSE on a distributed computer which may also include special‐purpose hardware, such as GRAPEs or GPUs, to accelerate computations. The current MUSE code base is publicly available as open source at http://muse.li. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards an accurate model for the Antennae galaxies
Authors: Karl S.J. , Naab T. , Johansson P.H. , Theis Ch. , Boily C.M. 
Published: November 2008

AbstractIn the framework of hierarchical structure formation ellipticals can form from merging of smaller disk galaxies. The nearby interacting ‘Antennae’ galaxy pair (NGC 4038/39) is one of the best‐studied local systems of merging spirals, thus presenting us with an ideal laboratory for the study of galaxy evolution models. The Antennae are believed to be in a state prior to their final encounter with rapid subsequent merging, which puts them in the first position of the Toomre (1977) merger sequence. Here we present first numerical high‐resolution, self‐consistent, smoothed particle hydrodynamics (SPH) simulations of the Antennae system, including star formation and stellar feedback, and compare our results to VLA H I observations by Hibbard et al. (2001). We are able to obtain a close, but not yet perfect match to the observed morphology and kinematics of the system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pairing mechanisms for binary stars
Authors: Kouwenhoven M.B.N. , Brown A.G.A. , Goodwin S.P. , Zwart S.F. Portegies , Kaper L. 
Published: November 2008

AbstractKnowledge of the binary population in stellar groupings provides important information about the outcome of the star forming process in different environments. Binarity is also a key ingredient in stellar population studies and is a prerequisite to calibrate the binary evolution channels. In these proceedings we present an overview of several commonly used methods to pair individual stars into binary systems, which we refer to as the pairing function.Many pairing functions are frequently used by observers and computational astronomers, either for the mathematical convenience, or because they roughly describe the expected outcome of the star forming process. We discuss the consequences of each pairing function for the interpretation of observations and numerical simulations. The binary fraction and mass ratio distribution generally depend strongly on the selection of the range in primary spectral type in a sample. These quantities, when derived from a binary survey with a mass‐limited sample of target stars, are thus not representative for the population as a whole. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local Galactic kinematics from revised Hipparcos catalogue
Authors: Kong D.‐L. , Zhu Z. , Yuan F.‐T. 
Published: November 2008

AbstractLocal stellar kinematic properties are reinvestigated. A main‐sequence sample of 12718 objects is picked out from a total of 117955 Hipparcos stars and some local kinematical parameters are re‐determined by dividing 19 subsamples mainly according to color index. The results are reasonably consistent with those derived from the initial Hipparcos data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Planar distribution of the galaxies in the Local Group
Authors: Pasetto S. , Chiosi C. , Grebel E.K. 
Published: November 2008

AbstractAdopting known data on positions and distances, we make use of analytical geometry and look for the plane that minimizes the distances of all galaxies to it. A planar distribution is found. We apply Hamilton's principle of minimum action to investigate the dynamics of the two major systems of the Local Group, the Milky Way and Andromeda, under the action of forces exerted by nearby galaxies or groups external to the Local Group. We find that the planar distribution is fully compatible with the minimum action and that the external force field is likely parallel to the plane. It pulls the galaxies of the Local Group without altering their planar distribution. Special care is paid to evaluate the robustness of this result. We present an explanation in the linear regime of the numerical results based on the compression effect described with the tidal tensor. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local group dwarf galaxies in the ΔCDM paradigm
Authors: Peñarrubia J. , Navarro J.F. , McConnachie A.W. 
Published: November 2008

AbstractWe report the results of two theoretical studies that examine the dynamics of stellar systems embedded within cold dark matter (CDM) halos in order to assess observational constraints on the dark matter content of Local Group dwarf spheroidals (dSphs). (i) Firstly, approximating the stellar and dark components by King and NFW models, respectively, we calculate the parameters of dark halos consistent with the kinematics and spatial distribution of stars in dSphs as well as with cosmological N‐body simulations. (ii) Subsequently, N‐body realization of these models are constructed to study the evolution of dwarf spheroidal galaxies (dSphs) driven by galactic tides. The analytical estimates highlight the poor correspondence between luminosity and halo mass. In systems where data exist, the stellar velocity dispersion profiles remains flat almost to the nominal “tidal” radius, implying that stars are deeply embedded within the dwarf halos and are therefore quite resilient to tidal disruption. This is confirmed by our N‐body experiments: halos need to lose more than 90% of their original mass before stars can be stripped. As tidal mass loss proceeds, the stellar luminosity, L, velocity dispersion, σ0, central surface brightness, Σ0, and core radius, Rc, decrease monotonically. Remarkably, the evolution of these parameters is solely controlled by the total amount of mass lost from within the luminous radius, which permit us to derive a tidal evolutionary track for each of them. This information is used to examine whether the newly‐discovered ultra‐faintMilkyWay dwarfs are tidally‐stripped versions of the “classical”, bright dwarfs. Although dSph tidal evolutionary tracks parallel the observed scaling relations in the luminosity‐radius plane, they predict too steep a change in velocity dispersion compared with the observational estimates. The ultra‐faint dwarfs are thus unlikely to be the tidal remnants of systems like Fornax, Draco, or Sagittarius. Despite spanning four decades in luminosity, dSphs appear to inhabit halos of comparable peak circular velocity, lending support to scenarios that envision dwarf spheroidals as able to form only in halos above a certain mass threshold. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cold stellar streams and dark matter substructure
Authors: Quinn D.P. , Wilkinson M.I. , Irwin M.J. 
Published: November 2008

AbstractWe present preliminary results from numerical experiments to examine the effect of dark matter subhaloes on the coherence of Cold Stellar Streams. We show that the evolution of the globular cluster, Pal 5, in a smooth Galactic potential can not account for the structure seen in its tidal tails. Work is ongoing to design indices that quantify the impact of subhaloes on stellar streams, and which may be measured from current observations of Pal 5. We introduce simple examples of indices that we use to analyse the numerical experiments and report on the potential of this approach to yield useful clues about the nature of Dark Matter. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Starburst triggered by compressive tides in galaxy mergers
Authors: Renaud F. , Theis Ch. , Boily C.M. 
Published: November 2008

AbstractThe tidal field of galaxies is known generally to be disruptive. However, in the case of galaxy mergers, a compressive mode of tidal wave may develop and last long enough to cocoon the formation of star clusters. Using an N‐body simulation of the Antennae galaxies, we derive the positions of these compressive regions and the statistics of their duration. Excellent agreement between the spatial distribution of tides and observed young clusters is found, while the characteristic e‐folding times of 10 to 30 Myr derived for the tidal field compare well with cluster formation time‐scales. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)