bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of environmental regulatory policies for sustainable emission reduction
Authors: Malcolm Andrés , Zhang Libin , Linninger Andreas A. 
Published: May 2006

AbstractCurrent environmental emission regulations typically follow a command‐and‐control approach mandating the installation of state‐of‐the‐art abatement technology to safeguard hard emission thresholds. However, this type of regulation offers no reward for conducting pollution prevention and technological research to reduce emissions below compliance levels through process innovation. Alternatively, market‐based regulations stimulate continued improvement of cleaner manufacturing practices by creating economic incentives for sustained waste reduction. The aim of this work is to furnish regulators and manufacturers with a concise tool for quantifying the impact of future regulatory scenarios. The proposed methodology employs realistic mathematical models of pollution abatement operations used in chemical, pharmaceutical, and specialty chemical manufacturing. It assesses the feasibility of treatment options, estimates their cost and expected emissions. Rigorous optimization techniques are introduced for managing regional emission reduction efforts at reasonable cost to manufacturers. The comprehensive mathematical programming formulations will enable plant managers to ascertain expected compliance cost, and regulators to design environmental regulations for reducing regional emissions at tolerable cost to industry. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Optical and physicochemical properties of silica‐supported TiO2photocatalysts
Authors: Marugán Javier , Van Grieken Rafael , Alfano Orlando M. , Cassano Alberto E. 
Published: May 2006

AbstractCommercial applications of photocatalysis in slurry reactors employing titanium dioxide particles present the disadvantage of the additional cost associated with the downstream catalyst separation. In past years a significant effort has been made to develop supported titania photocatalysts on particles of larger size in order to facilitate the sedimentation recovery process. In this work, two different silica materials have been used for preparing immobilized catalysts. Their physicochemical characteristics have been compared with those corresponding to two commercially available unsupported titanium dioxide catalysts. However, for reaction kinetics and reactor design purposes, three additional properties must be known: (i) the spectral specific radiation absorption coefficient, (ii) the spectral specific radiation scattering coefficient, and (iii) the asymmetry factor of a model for the angular distribution of the scattered photons (the phase function). They have been determined with specially designed spectrophotometer transmission, diffuse transmittance, and diffuse reflectance experiments and constitute the most significant addition to this contribution. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Enantiomeric Separation of Fluoxetine Derivatives on Polysaccharide‐Based Chiral Columns
Authors: Yu Li , Mei‐Li Fa , Jie‐Guo Xing 
Published: May 2006

AbstractA high performance liquid chromatography (HPLC) method employing amylose‐based chiral columns (Chiralpak AD‐RH and Chiralpak AD) and cellulose‐based chiral columns (Chiralcel OD) as chiral stationary phases have been developed for the enantiomeric separation of fluoxetine (FLX) derivatives. The FLX was derivatized with 4‐(N‐chloroformylmethyl‐N‐methyl)amino‐7‐nitro‐2,1,3‐benzoxadiazole (NBD‐COCl) and 4‐(N‐chloroformylmethyl‐N‐methyl)amino‐7‐N,N‐dimethylaminosulfonyl‐2,1,3‐benzoxadiazole (DBD‐COCl), respectively. Influence of the mobile phase composition and column temperature on the enantioseparation was discussed during the separation. On the basis of separation of derivatized FLX enantiomers, the paper also discussed the separation mechanism on the chiral stationary phases used.
The Square Kilometre Array: a new probe of cosmic magnetism
Authors: Gaensler B. M. 
Published: May 2006

AbstractMagnetic fields are a fundamental part of many astrophysical phenomena, but the evolution, structure and origin of magnetic fields are still unresolved problems in physics and astrophysics. When and how were the first fields generated? Are present‐day magnetic fields the result of standard dynamo action, or do they represent rapid or recent field amplification through other processes? What role do magnetic fields play in turbulence, cosmic ray acceleration and structure formation? I explain how the Square Kilometre Array (SKA), a next‐generation radio telescope, can deliver stunning new data‐sets that will address these currently unanswered issues. The foundation for these experiments will be an all‐sky survey of rotation measures, in which Faraday rotation toward > 107 background sources will provide a dense grid for probing magnetism in the Milky Way, nearby galaxies, and in distant galaxies, clusters and protogalaxies. Using these data, we can map out the evolution of magnetized structures from redshifts z > 3 to the present, can distinguish between different origins for seed magnetic fields in galaxies, and can develop a detailed model of the magnetic field geometry of the intergalactic medium and of the overall Universe. In addition, the SKA will certainly discover new magnetic phenomena beyond what we can currently predict or imagine. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Primordial magnetic seeds from string cosmology
Authors: Gasperini M. 
Published: May 2006

AbstractAfter a discussion of the inflationary production of primordial magnetic seeds and a brief review of various possible mechanisms, we concentrate on the analysis of the photon–dilaton coupling typical of string theory models. Particular attention is paid to the constraints to be imposed on the primordial seed spectrum and to the possibility of obtaining phenomenological signatures of heterotic and Type I superstrings, in principle accessible to present (or near‐future) observations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Primordial magnetic fields and CMB anisotropies
Authors: Subramanian K. 
Published: May 2006

AbstractPossible signatures of primordial magnetic fields on the Cosmic Microwave Background (CMB) temperature and polarization anisotropies are reviewed. The signals that could be searched for include excess temperature anisotropies particularly at small angular scales below the Silk damping scale, B‐mode polarization, and non‐Gaussian statistics. A field at a few nG level produces temperature anisotropies at the 5 µK level, and B‐mode polarization anisotropies 10 times smaller, and is therefore potentially detectable via the CMB anisotropies. An even smaller field, with B 0 < 0.1 nG, could lead to structure formation at high redshift z > 15, and hence naturally explain an early re‐ionization of the Universe. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The growth of baryonic structure in the presence of an isotropic magnetic field
Authors: Gazzola L. , King E. , Pearce F. , Coles P. 
Published: May 2006

AbstractWe follow the passive evolution of magnetic fields in SPH simulations to study their role in structure formation and galaxy clusters properties. Despite magnetic fields are not dynamically important for massive objects, they can still affect the properties of group‐size objects and core regions and also affect particle's entropy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Amplification of magnetic fields by supernova‐driven turbulence
Authors: Kim J. , Balsara D. S. 
Published: May 2006

AbstractObservations of μG magnetic fields in radio galaxies at cosmological epochs as early as around z = 2 have shortened the available time for dynamo action. This fact suggests that the mean‐field dynamo mechanism in a global galactic scale either is too slow to amplify a seed field generated by the Biermann battery effect to the level of the observed field strength at z ∼ 2 or needs much stronger seed fields of an order of 10–10 G. A “contamination” picture that amplified magnetic fields in smaller objects, such as stars or AGNs, within a relatively shorter timescale spread out through supernova ejecta, stellar winds, and AGN jets to nearby environments is gaining momentum. In line with this picture, we demonstrate, through three‐dimensional numerical experiments, that magnetic fields can be amplified by supernova‐driven turbulence with two orders of magnitude smaller e‐folding timescale than that of the mean‐field dynamo mechanism. Therefore, supernova‐driven turbulence may play an important role in amplifying small‐scale B ‐fields in any astrophysical systems that have harbored massive stars. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Biermann mechanism in primordial supernova remnants and seed magnetic fields
Authors: Hanayama H. , Takahashi K. , Kotake K. , Oguri M. , Ichiki K. , Ohno H. 
Published: May 2006

AbstractWe have studied the generation of magnetic fields by the Biermann mechanism in the pair‐instability supernovae explosions of the first stars. The Biermann mechanism produces magnetic fields in the shocked region between the bubble and interstellar medium (ISM), even if magnetic fields are absent initially. We have performed a series of two‐dimensional magnetohydrodynamic simulations with the Biermann term and estimate the amplitude and total energy of the produced magnetic fields. We .nd that magnetic fields with amplitude 10–14–10–17 G are generated inside the bubble, though the amount of magnetic fields generated depend on specific values of initial conditions. This corresponds to magnetic fields with total energy of 1028–1031 erg per each supernova remnant, which is strong enough to be the seed magnetic field for a galactic and/or interstellar dynamo. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Probing magnetohydrodynamical scenarios for jet production
Authors: de Gouveia Dal Pino E. M. 
Published: May 2006

AbstractLarge‐scale magnetic fields created by dynamo action along with magneto‐centrifugal and reconnection processes in accretion disks around the sources is currently the most accepted mechanism for jet production. Understanding the production of magnetic fields in jet‐accretion phenomena may be the key for understanding the origin of the large‐scale magnetic fields in galaxy clusters and in the Universe. Here, we discuss recent observational, theoretical and numerical results on jet phenomena that support the MHD scenarios for jet production. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic helicity in primordial and dynamo scenarios of galaxies
Authors: Brandenburg A. 
Published: May 2006

AbstractSome common properties of helical magnetic fields in decaying and driven turbulence are discussed. These include mainly the inverse cascade that produces fields on progressively larger scales. Magnetic helicity also restricts the evolution of the large‐scale field: the field decays less rapidly than a non‐helical field, but it also saturates more slowly, i.e. on a resistive time scale if there are no magnetic helicity fluxes. The former effect is utilized in primordial field scenarios, while the latter is important for successfully explaining astrophysical dynamos that saturate faster than resistively. Dynamo action is argued to be important not only in the galactic dynamo, but also in accretion discs in active galactic nuclei and around protostars, both of which contribute to producing a strong enough seed magnetic field. Although primordial magnetic fields may be too weak to compete with these astrophysical mechanisms, such fields could perhaps still be important in producing polarization effects in the cosmic background radiation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The nonlinear galactic dynamo and magnetic helicity transport
Authors: Kleeorin N. , Moss D. , Rogachevskii I. , Sokoloff D. 
Published: May 2006

AbstractWe discuss nonlinear mean‐field galactic dynamo models and associate a universal mechanism for saturation of the dynamo with the transport of magnetic helicity. The crucial point for saturation of the dynamo is the existence of a non‐zero flux of magnetic helicity. We demonstrate that this saturation mechanism is quite insensitive to the form of this helicity flux. In that sense this is a robust mechanism which limits the growth of the mean magnetic field.Without this flux, the total magnetic helicity is conserved locally and the strength of the saturated mean magnetic field is very small compared to the equipartition strength. The inclusion of a flux of magnetic helicity means that the total magnetic helicity is not conserved locally because the magnetic helicity of small‐scale magnetic fluctuations is redistributed by the flux. The equilibrium state is given by a balance between magnetic helicity production and magnetic helicity transport. The equilibrium value of the galactic large‐scale magnetic field is given approximately by equipartition between the kinetic energy densities of the interstellar turbulence and the mean magnetic field.We also compare the action of algebraic and dynamic nonlinearities in the galactic dynamo. The algebraic α quenching saturates the dynamo, however a more realistic simultaneous quenching of the α effect and turbulent magnetic diffusion cannot saturate the growth of the mean magnetic field; this can only be achieved by the combined effects of algebraic and dynamic nonlinearities. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamo coefficients in Parker unstable disks with cosmic rays
Authors: Otmianowska‐Mazur K. , Kowal G. , Hanasz M. 
Published: May 2006

AbstractWe investigate a three‐dimensional (3D) numerical model of the Parker instability with cosmic rays and shear in a galactic disk and compute the components of the dynamo coefficients $ \hat \alpha $ and $ \hat \beta $ from the electromotive force (EMF) obtained directly from our simulations. In our model we apply well‐known statistical procedures in order to fit the modeled EMF in terms of the dynamo tensors. Nevertheless, we do not solve all problems with the physical interpretation of the dynamo tensors prescribed in the way of Rädler (1980). We find that the presented methods give us the possibility to compute the coefficients with a desired statistical quality. The obtained values of αxx (along the radial direction in a galaxy) are of order of a few km/s, while the values of αyy (along the azimuthal direction) are one order of magnitude smaller. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
From Parker and thermal instabilities to the formation of giant molecular clouds
Authors: Kosiński R. , Hanasz M. 
Published: May 2006

AbstractWe study the Parker instability (PI) under the influence of heating and cooling processes. We distinguish two models with different heating functions. On the base of linear stability analysis, we find that the properties of PI in such a system are significantly different with respect to the adiabatic and isothermal cases. We find that in case of thermally stable equilibrium, PI operating in presence of additional heating sources, postulated by Reynolds et al. (1999), and cooling described by Dalgarno & McCray (1972), leads to a decrease of temperature in magnetic valleys. Numerical simulations show that this behavior promotes a transition of gas to thermally unstable regime. In consequence the gas density grows up by an order of magnitude and the condensed gas clumps acquire compact shapes. Our results lead to the conclusion that PI can trigger the formation of giant molecular clouds complexes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Toruń 6‐cm polarimetry of the MilkyWay
Authors: Ryś S. , Chyży K. T. , Kus A. , Pazderski E. , Soida M. , Urbanik M. 
Published: May 2006

AbstractWe present first results of a radio continuum and polarization survey of the Milky Way at 4.7 GHz carried out with the 32‐m radio telescope in Toruń. The survey is much less affected by depolarization effects than previous measurements at lower frequencies. This enables the study of magnetic field structure and its interrelations with particular features in the interstellar medium to much larger distances from the Sun. Our preliminary total power map shows a good association of radio features with galactic star‐forming regions while the polarization data reveal an increasing coherence of magnetic fields away from the Galaxy's mid‐plane. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The large scale magnetic field configuration in the Sombrero galaxy – persistence during galaxy evolution?
Authors: Krause M. , Wielebinski R. , Dumke M. 
Published: May 2006

AbstractRadio polarization observations at 4.86 and 8.35 GHz of the nearby edge‐on galaxy M 104 revealed a large‐scale magnetic field in this early‐type spiral. This is to our knowledge the first detection of a regular magntic field in an Sa galaxy in the radio range. The magnetic field orientation in M 104 is predominantly parallel to the disk but has also vertical components at larger z‐distances from the disk, i.e. a field configuration typical for normal edge‐on spiral galaxies. Bolometer observations at 345 GHz data pertain to the cold dust content of the galaxy. Despite the optical appearance of the object with the huge dust lane, its dust content is smaller than that of more late‐type spirals. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic field evolution in the perturbed Virgo spiral NGC 4654 – MHD 3D modeling
Authors: Soida M. , Otmianowska‐Mazur K. , Chyży K. T. , Vollmer B. 
Published: May 2006

AbstractThe Virgo cluster spiral galaxy NGC 4654 shows clear signs of interaction, but the nature of this interaction is still unclear. Two possibilities have been discussed: ram pressure stripping and tidal interaction with NGC 4639. Dynamical simulations speak in favor of the tidal interaction with small addition of constant ram pressure.We present synthetic polarized intensity maps calculated using 3D MHD simulations based on gas velocity field evolution. Our results are compared with recent Effelsberg 100 m telescope observations of NGC 4654. The MHD model and the observations are qualitatively similar. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evolution of magnetic fields at high redshift
Authors: Zweibel E.G. 
Published: May 2006

AbstractThe origin of magnetic fields in the Universe is a cosmology problem. The evolution of the field is a plasma physics problem. I review these problems and focus on magnetogenesis in accretion disks, specifically, the transition from the Biermann battery, which creates seed fields, to amplification by turbulence driven by magnetorotational instability. In collisional disks, there is a gap between the fieldstrength characteristic of the battery and the fieldstrength necessary to sustain magnetorotational instability, but in collisionless disks the transition occurs at low fieldstrength. Because collisionless disks are generally hot, and have short dynamical times, they are likely to be small. Thus, in the battery scenario, magnetic fields on large scales were built from fields created in many small sources. Simple estimates based on turbulent diffusion suggest that galaxies and the cores of galaxy clusters can be magnetized in this way, but not the intergalactic medium at large. The problem of creating a large‐scale field remains unsolved. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Probing distant magnetic fields with M82‐type galaxies
Authors: Wielebinski R. 
Published: May 2006

AbstractI present the results of recent 9 mm observations of the starburst galaxy M 82 with the Effelsberg 100‐m radio telescope. The magnetic fields deduced from these observations are in good agreement with previous multifrequency VLA observations. The general pattern of azimuthal magnetic fields along the disc of the galaxy and vertical fields in the central region, as seen in most nearby galaxies, is confirmed to exist also in M 82. Since the starburst galaxy M 82 is a very powerful radio source similar objects should be visible at large distances. Possibly the distant magnetic Universe could be probed by observing sources similar to M 82 with the new generation of radio telescopes. Here the ALMA telescope holds great promise for the near future. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic fields in jets: ordered or disordered?
Authors: Laing R. A. , Canvin J. R. , Bridle A. H. 
Published: May 2006

AbstractThe question of the degree of order in the magnetic fields of relativistic jets is important to any understanding of their production. Both vector‐ordered (e.g. helical) and disordered, but anisotropic fields can produce the high observed degrees of polarization. We outline our models of jets in FR I radio galaxies as decelerating relativistic flows. We then present theoretical calculations of the synchrotron emission from different field configurations and compare them with observed emission from FR I jets. We show that large‐scale helical fields (with significant poloidal and toroidal components) are inconsistent with observations. The combination of an ordered toroidal and disordered poloidal component is consistent with our data, as is an entirely disordered field. Jets must also contain small, but significant amounts of radial field. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Faraday rotation variations along radio jets: the magnetic field in galaxy and group halos
Authors: Laing R. A. , Canvin J. R. , Cotton W. D. , Bridle A. H. , Parma P. 
Published: May 2006

AbstractOur modelling of FR I radio jets as decelerating, relativistic flows allows us to derive their orientations accurately. We present images of Faraday rotation for two of these these objects (3C 31 and NGC 315) and show that the fluctuations of rotation measure (RM) are larger in the fainter (receding) jets, as expected if the rotation occurs in the hot galaxy/group halos. The gas density is much lower in NGC 315 and the RM fluctuations are only just detectable. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
3D MHD interactions of jets with cluster media
Authors: O'Neill S. M. , Jones T. W. , Tregillis I. L. , Ryu D. 
Published: May 2006

AbstractAs an initial step in a program to examine the interactions of AGN jets with magnetized cluster media, we have carried out high resolution, 3D MHD medium‐to‐high luminosity jet simulations in both uniform and stratified, cluster‐like atmospheres extending over distances ∼ 200 kpc. The steady jets asymptotically deposit approximately 1/2 of their power into ambient thermal energy, almost independent of the jet Mach number or the external density gradient. Nearly 1/4 of the jet power goes directly into irreversible, dissipative heating of the ICM. The remaining energy is mostly stored in the jet backflow cocoon. Magnetic energy introduced by the jet is generally amplified, especially by sheared flows. We also examined the dynamical evolution of the jets and their cocoons, comparing them to simple analytic models. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
RM‐synthesis of the Perseus cluster
Authors: Brentjens M. A. , de Bruyn A. G. 
Published: May 2006

AbstractWe present low frequency radio polarimetric observations of the Perseus cluster. The data were taken with the Westerbork Synthesis Radio Telescope (WSRT) between 315–360 MHz. We have discovered faint, extended, highly polarized emission that we associate with the Perseus cluster (de Bruyn & Brentjens 2005). We propose that at least one of these structures is associated with large‐scale structure formation gas inflow from the Perseus‐Pisces supercluster. The extragalactic emission is seen through a polarized Galactic synchrotron foreground screen. The discovery was made possible by a novel rotation measure analysis technique, called Faraday Rotation Measure Synthesis, or RM‐synthesis for short (Brentjens & de Bruyn 2005). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)