bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mixing in Sub‐micron Ducts
Authors: Nauman E.B. , Nigam A. 
Published: February 2004

AbstractThis paper considers a class of fluidic devices, anticipated to become important in the near future, where characteristic channel dimensions are in the range 0.1 to 1.0 microns. Typical current applications of microfluidics have device sizes of 10 to 100 micron, this is sufficiently small to force laminar flow but not so small that molecular diffusion is a dominant factor. In the smaller devices contemplated here, diffusion is important and existing mixing strategies and correlations are no longer applicable. Novel results and interesting complexities are discussed for reactive, single and two phase flows in sub‐micron channels.
Effects of Fine Scale Turbulent Flow and Mixing in Agglomerative Precipitation
Authors: Bałdyga J. , Jasińska M. , Krasiński A. , Rožeń A. 
Published: February 2004

AbstractPrecipitation of a solid product from aqueous ionic solutions, including mixing, fast chemical reaction, nucleation, growth and agglomeration of crystals is considered. This work concentrates on the phenomenon of particle agglomeration which dominates the precipitation process at high supersaturation. Modeling of particle collision includes effects of bulk fluid motion, Brownian diffusion and colloidal forces for particles of equal and unequal size. The concept of probability of agglomeration based on multifractal formalism is introduced and applied. A simplified version of the model is linked to CFD and results of computations are compared with experimental data for barium sulfate precipitation.
A Multi‐Block Approach to Obtain Angle‐Resolved PIV Measurements of the Mean Flow and Turbulence Fields in a Stirred Vessel
Authors: Khan F.R. , Rielly C.D. , Hargrave G.K. 
Published: February 2004

AbstractTwo‐dimensional Particle Image Velocimetry (PIV) measurements have been used to characterize the complex turbulent flow generated by a T/3 45° pitched‐blade down‐flow turbine, operated at Re ≈ 5 · 104, in a fully turbulent stirred vessel. To maintain high spatial resolution when viewing the whole vessel, a multi‐block approach has been developed, which combines data from different fields of view into a composite flow map. Using 500 measurements of instantaneous u and v velocity fields, angle‐resolved mean velocity maps and turbulence properties, such as the RMS velocities and the turbulence kinetic energy, have been estimated near to the blade, as well as in the bulk of the vessel, at a spatial resolution of between 1 and 2 mm. Vorticity maps have also been calculated to help visualize the trailing vortex structures close to the impeller blades and integral length scales have been estimated from the two‐dimensional spatial auto‐correlation function. It is shown than the common assumption that the integral length scale is about half the blade width is an overestimate close to the impeller and an underestimate far from the impeller.
Influence of Physical Properties on Drop Size Distribution of Stirred Liquid‐Liquid Dispersions
Authors: Kraume M. , Gäbler A. , Schulze K. 
Published: February 2004

AbstractAn experimental investigation was carried out to analyse the influence of coalescence behavior on drop size distributions in stirred liquid‐liquid dispersions. An endoscope measurement technique was applied that allowed the determination of drop sizes even with high volumetric dispersed phase fractions φ of up to 0.5. The influence of pH and addition of ions was studied by shaking and stirring experiments. For high coalescence rates, the results show self‐similar drop size distributions independent of all other parameters. With low coalescence rates the Sauter diameter d32 decreases and the distributions become narrower. When phase ratios were increased the common correlation d32 ∼ (1 + const. φ) We–0.6 did not lead to a reliable description of the mean drop sizes due to coalescence effects.
Particle Flow Modelling in Slurry‐Fed Stirred Vessels
Authors: Scargiali F. , Grisafi F. , Cermakova J. , Machon V. , Brucato A. 
Published: February 2004

AbstractDespite its importance, experimental information on the Residence Time Distribution (RTD) of solid particles in continuous‐flow stirred vessels is still scant. In this work, experimental data on particle RTD in a high‐aspect‐ratio vessel stirred by three equally‐spaced Rushton turbines, obtained by means of Twin Systems Approach (TSA), are employed to assess the suitability of the well known Axial‐Dispersion Model to describe particle behavior in the investigated system. The data analysis and model parameter assessment are preceded by a discussion on the utility of self‐recirculated systems in carrying out experiments concerning continuous slurry‐fed apparatuses. In particular, the suitability of single recirculated systems is discussed and a way to extract numerical RTD data from the relevant experiments is proposed. The advantages and disadvantages of employing instead a couple of twin systems, as it was actually done to obtain the experimental data employed in this work, is shortly discussed.
The Future of Mixing Research
Authors: Kresta Suzanne M. , Krebs R. , Martin T. 
Published: February 2004

AbstractThis paper is the result of a plenary discussion session held at the 11th European Conference on Mixing. Three perspectives on mixing research are explored: that of the industrialist, the equipment manufacturer, and the academic researcher. There was strong agreement that, while the one dimensional problems are reasonably well understood and many engineers thus perceive that mixing is simple, current practice actually requires us to address complex, multi‐dimensional problems with interactions between mixing, reaction, multi‐phase physics, surface phenomena, and transport phenomena. Understanding these multi‐scale, multi‐mechanism problems requires models which include interactions between the phenomena, and allow the effects of these interactions to emerge. Developing these models will require us to shift our perspective on mixing from one of equipment design to one of the mixing field as a fundamental physical mechanism.
Mischvorgänge: Klassische Methoden und Computational Fluid Dynamics in der industriellen Praxis
Authors: Himmler K. , Schierholz W. F. 
Published: February 2004

AbstractMisch‐ und Rührvorgänge zählen zu den wichtigsten Grundoperationen der Verfahrenstechnik. Aus diesem Grund ist die Auslegung und Optimierung dieser Teilprozesse von großer Bedeutung für die Entwicklung und das Design neuer Verfahren. Bei Siemens Axiva werden Misch‐ und Rührvorgänge im Rahmen des „Integrated Process Development”︁ (IPD) sowohl mit klassischen Methoden als auch mit Computational Fluid Dynamics (CFD) untersucht. In diesem Beitrag werden Stärken und Schwächen beider Methoden an einigen Beispielen aufgezeigt und diskutiert. Je nach Frage‐ und Aufgabenstellung kann es sinnvoll sein, ein Problem mit experimentellen Methoden, mit CFD oder mit beiden Methoden gemeinsam zu untersuchen.
Produktdesign – Beschleunigte Entwicklung von Produkten durch Einbeziehung des Kunden
Authors: Rähse W. 
Published: February 2004

AbstractIm Zuge der Globalisierung erfolgte in den 90er Jahren eine Besinnung der chemischen Industrie auf ihre Kernkompetenz: die Einführung innovativer Produkte. Zur effektiven Entwicklung wurden in einigen Unternehmen die Organisations‐ und Projektstrukturen geändert. Heute steuert ein Team aus Produkt‐ und Verfahrensentwicklern gemeinsam mit dem Marketing die Einzelschritte der Produktentwicklung unter Einbeziehung interner und externer Fachleute. Die Kunden werden von der Produktidee bis zum Markteintritt an der Entwicklung beteiligt, zum einen zur zielgerichteten, beschleunigten Abwicklung und zum anderen zur Minimierung des Floprisikos. Die Konkretisierung neuer Produktideen erfolgt durch Aufzeigen der chemischen und der technischen Möglichkeiten zur Umsetzung, bevor eine Bewertung des Vorschlages erfolgt. Anhand des Innovations‐„Thermometers”︁ kann die Innovationshöhe eingeordnet werden, mit Hilfe des „Barometers”︁ lassen sich die Marktchancen von Ideen abschätzen. Die Produktentwicklung muss bei Marktneuheiten zur Sicherung eines Markterfolgs sehr schnell erfolgen. Eine beschleunigte Produktentwicklung erfordert die Erfüllung von zehn Voraussetzungen, die im Detail erklärt werden. Am Beispiel fester „Waschmittel”︁ wird die Ermittlung von Kundenbedürfnissen diskutiert. Zur Beeinflussung des Partikeldesigns, insbesondere zur Verbesserung der Ästhetik, existiert eine Reihe interessanter, in den Herstellprozess integrierbarer Technologien.
Efferent connections of the nucleus of the lateral olfactory tract in the rat
Authors: Santiago Adriana C. , Shammah‐Lagnado Sara J. 
Published: February 2004

AbstractThe efferent connections of the nucleus of the lateral olfactory tract (LOT) were examined in the rat with the Phaseolus vulgaris leucoagglutinin (PHA‐L) technique. Our observations reveal that layers II and III of LOT have largely segregated outputs. Layer II projects chiefly ipsilaterally to the olfactory bulb and anterior olfactory nucleus, bilaterally to the anterior piriform cortex, dwarf cell cap regions of the olfactory tubercle and lateral shell of the accumbens, and contralaterally to the lateral part of the interstitial nucleus of the posterior limb of the anterior commissure. Layer III sends strong bilateral projections to the rostral basolateral amygdaloid complex, which are topographically organized, and provides bilateral inputs to the core of the accumbens, caudate‐putamen, and agranular insular cortex (dorsal and posterior divisions). Layer II projects also to itself and to layers I and II of the contralateral LOT, whereas layer III projects to itself, to ipsilateral layer II, and to contralateral layer III of LOT. In double retrograde labeling experiments using Fluorogold and cholera toxin subunit b tracers, LOT neurons from layers II and III were found to provide collateral projections to homonymous structures on both sides of the brain. Unlike other parts of the olfactory amygdala, LOT neither projects directly to the extended amygdala nor to the hypothalamus. Thus, LOT seemingly influences nonpheromonal olfactory‐guided behaviors, especially feeding, by acting on the olfactory bulb and on ventral striatal and basolateral amygdaloid districts that are tightly linked to lateral prefrontal cortical operations. J. Comp. Neurol. 471:314–332, 2004. © 2004 Wiley‐Liss, Inc.
Suprachiasmatic nucleus input to autonomic circuits identified by retrograde transsynaptic transport of pseudorabies virus from the eye
Authors: Smeraski Cynthia A. , Sollars Patricia J. , Ogilvie Malcolm D. , Enquist Lynn W. , Pickard Gary E. 
Published: February 2004

AbstractIntraocular injection of the Bartha strain of pseudorabies virus (PRV Bartha) results in transsynaptic infection of the hypothalamic suprachiasmatic nucleus (SCN), a retinorecipient circadian oscillator. PRV Bartha infection of a limited number of retinorecipient structures, including the SCN, was initially interpreted as the differential infection of a subpopulation of rat retinal ganglion cells, followed by replication and anterograde transport via the optic nerve. A recent report that used a recombinant strain of PRV Bartha (PRV152) expressing enhanced green fluorescent protein demonstrated that SCN infection actually results from retrograde transneuronal transport of the virus via the autonomic innervation of the eye in the golden hamster. In the present study using the rat, the pattern of infection after intravitreal inoculation with PRV152 was examined to determine if infection of the rat SCN is also restricted to retrograde transsynaptic transport. It was observed that infection in preganglionic autonomic nuclei (i.e., Edinger‐Westphal nucleus, superior salivatory nucleus, and intermediolateral nucleus) precedes infection in the SCN. Sympathetic superior cervical ganglionectomy did not abolish label in the SCN after intraocular infection, nor did lesions of parasympathetic preganglionic neurons in the Edinger‐Westphal nucleus. However, combined Edinger‐Westphal nucleus ablation and superior cervical ganglionectomy eliminated infection of the SCN. This observation allowed a detailed examination of the SCN contribution to descending autonomic circuits afferent to the eye. The results indicate that in the rat, as in the hamster, SCN infection after intraocular PRV152 inoculation is by retrograde transsynaptic transport via autonomic pathways to the eye. J. Comp. Neurol. 471:298–313, 2004. © 2004 Wiley‐Liss, Inc.
Distribution of anterogradely labeled trigeminal and auditory nerve boutons on abducens motor neurons in turtles: Implications for in vitro classical conditioning
Authors: Keifer Joyce , Mokin Maxim 
Published: February 2004

AbstractA conditioned abducens nerve response is generated in in vitro brainstem preparations from turtles by pairing a weak conditioned stimulus (CS) applied to the auditory nerve that immediately precedes an unconditioned stimulus (US) applied to the trigeminal nerve. Tract‐tracing studies showed direct projections from auditory and trigeminal nerves to abducens motor neurons. In light of these findings for convergent CS‐US inputs, it is hypothesized that auditory and trigeminal nerve synaptic inputs onto abducens motor neurons are in spatial proximity because the CS is a weak input that may be required to be near the US inputs to have an associative effect, and conditioning occurs only when the CS and US are temporally separated by less than 100 ms. This study examined the spatial relationship of 133 anterogradely labeled synaptic boutons conveying CS or US information on retrogradely labeled abducens motor neurons. The results show that trigeminal and auditory nerve terminal fields occupy primarily the soma and proximal dendrites of abducens motor neurons. Quantitative analysis shows that the majority of labeled boutons (76% and 85% from injections of the trigeminal and auditory nerves, respectively) were apposed to somata or were localized to dendritic segments no more than about 30 μm from the nucleus. There were no quantitative differences between trigeminal and auditory nerve boutons in terms of their localization on dendrites or bouton diameter. Finally, triple labeling experiments demonstrated that individual abducens motor neurons receive inputs from both nerves and that these inputs may be in close spatial proximity to one another. This synaptic arrangement allows for the possibility that in vitro abducens conditioning is generated by coincident CS‐US detection mediated by NMDA receptors and may utilize a Hebbian‐like plasticity mechanism. J. Comp. Neurol. 471:144–152, 2004. © 2004 Wiley‐Liss, Inc.
NT3 expressed in skin causes enhancement of SA1 sensory neurons that leads to postnatal enhancement of Merkel cells
Authors: Krimm Robin F. , Davis Brian M. , Woodbury C. Jeffery , Albers Kathryn M. 
Published: February 2004

AbstractTo determine the role of NT3 in the postnatal maturation of Merkel cell (MC) sensory neurite complexes (touch domes), we examined the development of their neural and end‐organ components in wild‐type and transgenic mice that overexpress NT3 (NT3‐OE). Touch domes are sensory complexes of the skin that contain specialized MCs innervated by slowly adapting type 1 (SA1) neurons. Touch domes are dependent on NT3 and, though formed in newborn mice that lack NT3, are severely depleted during postnatal maturation. Mice that overexpress NT3 in the skin have larger touch domes characterized by enhanced neural innervation and MC number. In this study, we asked how this NT3‐mediated enhancement occurs, whether through stimulatory effects of NT3 on the SA1 neuron, or the MC, or both. The innervation density and number of MCs associated with each touch dome were measured in wild‐type and transgenic animals at postnatal times. In newborn NT3‐OE mice, touch dome innervation was enhanced. Surprisingly, however, the number of MCs was lower in newborn NT3‐OE animals than in wild‐type littermates, and equivalent numbers were not reached until postnatal day 8 (PN8). Not until the PN12 and PN16 time points did MCs increase in NT3‐OE mice. To examine the neural dependence of MCs in NT3‐OE mice, touch domes were chronically denervated by resecting dorsal cutaneous nerves. Both wild‐type and NT3‐OE animals showed similar depletion in the number of MCs associated with touch domes. These data indicate that NT3 is not a survival factor for MCs and that the NT3‐mediated enhancement of MC number is indirect and neurally dependent. J. Comp. Neurol. 471:352–360, 2004. © 2004 Wiley‐Liss, Inc.
Morphology of brachial segments in mudpuppy (Necturus maculosus) spinal cord studied with confocal and electron microscopy
Authors: Jovanovic Ksenija , Burke Robert E. 
Published: February 2004

AbstractThe isolated brachial spinal cord of Necturus maculosus is useful for studies of neural networks underlying forelimb locomotion, but information about its cellular morphology is scarce. We addressed this issue by using confocal and electron microscopy. Remarkably, the central region of gray matter was aneural and consisted exclusively of a tenuous meshwork of glial fibers and large extracellular spaces. Somata of motoneurons (MNs) and interneurons (INs), labeled by retrograde transport of fluorescent tracers from ventral roots and axons in the ventrolateral funiculus, respectively, were confined within a gray neuropil layer abutting the white matter borders, whereas their dendrites projected widely throughout the white matter. About one‐third of labeled INs were found contralaterally, with axons crossing ventral to a thick layer of ependyma surrounding the central canal. Lateral MN dendrites proliferated under the pial surface to form a dense, thin (1–2 μm) plexus immediately beneath a thin layer of glial fibrillary acidic protein‐positive glia limitans. The latter contained arrays of unusual tubular structures (diameter 200–400 nm, length 3 μm) that resembled mitochondria but lacked double membranes or cristae. Dorsal roots (DRs) produced dense presynaptic arbors within a wedge‐shaped afferent termination zone medial to the dorsal root entry, within which dendrites of MNs and INs mingled with dense collections of synaptic boutons. Our data suggest that a major fraction of synaptic interactions takes place within the white matter. This study provides a detailed foundation for designing electrophysiological experiments to study the neural circuits involved in locomotor pattern generation. J. Comp. Neurol. 471:361–385, 2004. Published 2004 Wiley‐Liss, Inc.
Presence and induction of the enzyme NAD(P)H: Quinone oxidoreductase 1 in the central nervous system
Authors: Stringer Janet L. , Gaikwad Amos , Gonzales Bianca N. , Long Delwin J. , Marks Latoia M. , Jaiswal Anil K. 
Published: February 2004

AbstractNAD(P)H:quinone oxidoreductase 1 (NQO1) catalyzes a reductive detoxification that is thought to protect cells against the adverse effects of quinones and related compounds. NQO1 activity is present in all tissues. Absence of the enzyme produces abnormalities in the redox state and seizures, suggesting an important role of the protein in the central nervous system. Immunohistochemical analysis showed that the protein was found throughout the brain of the adult rat and mouse, with complete absence of the protein in brains from NQO1‐/‐ mice. NQO1 was not seen in any neuronal population, but was localized to Bergmann glial in the cerebellum and a subset of the oligodendrocytes throughout the brain. Prolonged seizures induced in adult rats with kainic acid resulted in an increase in activity of the enzyme throughout the brain, most prominently in the cerebellum, but immunoreactivity did not appear in neurons. Comparison of the axons in the corpus callosum from a wild‐type mouse to a knockout mouse showed that myelin is produced in the absence of NQO1, but there appears to be more small‐diameter axons in the knockout animal. These results suggest that NQO1 has a role in myelination in the central nervous system or in the insulating/wrapping function of glial cells. J. Comp. Neurol. 471:289–297, 2004. © 2004 Wiley‐Liss, Inc.
Mixing in simple models for turbulent diffusion
Authors: Tabak Esteban G. , Tal Fabio A. 
Published: February 2004

AbstractSimple turbulent diffusive models are proposed as conceptual tools for exploring scenarios involving mixing of stratified flows. Applications include the dynamics of the ocean's top mixed layer, shear instability, breaking internal waves, and turbulent stirring of sharp interfaces. A novel measure of mixing is developed, based on arguments from statistical physics. It is shown that, under turbulent diffusion, this measure grows, and that there are strong indications that, under stirring, flows tend to settle down at a maximum of this measure, subject to global dynamical constraints. © 2004 Wiley Periodicals, Inc.
Adiabatic charge transport and the Kubo formula for Landau‐type Hamiltonians
Authors: Elgart Alexander , Schlein Benjamin 
Published: February 2004

AbstractThe adiabatic charge transport is investigated in a two‐dimensional Landau model perturbed by a bounded potential at zero temperature. We show that if the Fermi level lies in a spectral gap, then in the adiabatic limit the accumulated excess Hall charge is given by the linear response Kubo‐Štreda formula. The proof relies on the expansion of Nenciu, some generalized phase space estimates, and a bound on the speed of propagation. © 2004 Wiley Periodicals, Inc.
Parallel LU factorization of sparse matrices on FPGA‐based configurable computing engines
Authors: Wang Xiaofang , Ziavras Sotirios G. 
Published: February 2004

AbstractConfigurable computing, where hardware resources are configured appropriately to match specific hardware designs, has recently demonstrated its ability to significantly improve performance for a wide range of computation‐intensive applications. With steady advances in silicon technology, as predicted by Moore's Law, Field‐Programmable Gate Array (FPGA) technologies have enabled the implementation of System‐on‐a‐Programmable‐Chip (SOPC or SOC) computing platforms, which, in turn, have given a significant boost to the field of configurable computing. It is possible to implement various specialized parallel machines in a single silicon chip. In this paper, we describe our design and implementation of a parallel machine on an SOPC development board, using multiple instances of a soft IP configurable processor; we use this machine for LU factorization. LU factorization is widely used in engineering and science to solve efficiently large systems of linear equations. Our implementation facilitates the efficient solution of linear equations at a cost much lower than that of supercomputers and networks of workstations. The intricacies of our FPGA‐based design are presented along with tradeoff choices made for the purpose of illustration. Performance results prove the viability of our approach. Copyright © 2004 John Wiley & Sons, Ltd.