bluuebunny/crossref_metadata_2025_split huggingface dataset:
PVD‐Niedertemperaturbeschichtung für Bauteile zur Integration tribologischer Funktionen in die Oberfläche
Authors: Bobzin K. , Lugscheider E. , Maes M. 
Published: October 2004

AbstractDie Realisierung neuer, komplexer Schichtsysteme und vor allem die Niedertemperaturbeschichtung für Bauteile sind mit einem enormen Prozessaufwand verbunden. Mithilfe modernster Prozesstechnik, insbesondere der Pulstechnologie, können zunehmend leistungsfähigere Werkstoffsysteme entwickelt werden, die den hohen Anforderungen in den Bauteilprüfständen standhalten. Für die Bauteilbeschichtung spielen sowohl die Temperatursenkung bis unter 160 °C als auch Reinigungsprozesse eine entscheidende Rolle. Plasmaätzprozesse müssen an die Grundwerkstoffe angepasst und optimiert werden. Des weiteren sind gute Reibeigenschaften bei Bauteilen häufig entscheidender als der Verschleißschutz.Die Entwicklung des Schichtsystems ZrCg basiert auf der Idee, verschleißfeste und reibmindernde PVD‐Schichten (Physical Vapour Deposition) zu erzeugen, die nach einer Einlaufphase eine glatte Oberfläche mit einem nahezu stationären Verschleißzustand erreichen. Die Gradierung wird durch eine kontinuierliche Erhöhung des Reaktivgasflusses des Kohlenstoffträgergases erzeugt. An der Oberfläche der Schicht bildet sich dann eine scherweiche Lage aus Kohlenstoff und innerhalb der Schicht bildet sich beim Durchlaufen der stöchiometrischen Zusammensetzung von C und Zr die Hartstoffphase ZrC. Um eine gute Anbindung an den Grundwerkstoff zu gewährleisten, beginnt der Beschichtungsprozess mit einer weicheren, metallischen Zr‐Schicht als Haftvermittler. Die bisher entwickelten Systeme ZrCg zeigen ein hohes Potenzial für die Bauteilbeschichtung und unterschiedliche Varianten konnten an Triboprüfständen für Getriebe, Axiallager und hydraulische Verdrängereinheiten bereits erfolgreich getestet werden.Neben Kohlenstoffschichten zeigen CrN‐Schichten ein großes Potenzial für die Bauteilbeschichtung. Zwar sind Cr‐Basis‐Schichten weicher als Ti‐Basis‐Schichten, dennoch liegen ihre Härtewerte aber deutlich über denen der niedriglegierten Stahlsubstrate, so dass eine Verbesserung des Abrasionswiderstandes erreicht wird. Ein wesentlicher Vorteil der Cr‐Basis‐Schichten ist ihr niedriges E‐Modul, durch das Cr‐Basis‐Schichten bei Wechselbelastungen im Impact‐Test deutlich höhere Standzeiten erreichen. Eine Weiterentwicklung der CrN‐Schichten stellt das System (Crx,Al1‐x)N dar, das umfangreich untersucht wurde. Neben einer sehr guten Korrosionsschutzwirkung zeichnet sich (Crx,Al1‐x)N durch einen hohen Adhäsionswiderstand aus. Durch die Zugabe von AlN zum CrN lässt sich die Härte bei gleichzeitiger Senkung des E‐Moduls, steigern.
Abrasive wear mechanisms of VPS‐ and HVOF‐sprayed TiC‐Ni based nanocrystalline coatings
Authors: Qi X. , Aust E. , Eigen N. , Gärtner F. , Bormann R. 
Published: October 2004

AbstractNanocrystalline coatings have a high potential for various engineering applications, e.g. against wear of rolls in the paper fabrication and as corrosion protection. Using vacuum plasma spray (VPS) and high velocity oxy‐fuel (HVOF) spray techniques, coating materials are exposed to high flame temperatures only for less than a millisecond. Therefore, high‐energy milled powders can be used as feedstock material without losing its nanocrystalline microstructure during the thermal spray process. In this way, homogeneous, dense nanocrystalline coatings can be produced, which show enhanced hardness, thus obtaining promising superior wear resistance. In the present study, (Ti,Mo)(C,N)‐45vol.%NiCo nanocrystalline coatings were prepared by VPS‐ and HVOF‐spraying of high‐energy milled powders. Abrasive wear tests JIS H 8615 with varying number of strokes and scratch tests with a Vickers indenter were applied to produce wear traces on the polished surfaces of the nanocrystalline coatings. Abrasive wear behaviour was analyzed by investigating the surface morphologies with optical microscopy (OM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Experimental results indicate that the VPS‐coating has higher abrasive wear resistance than the HVOF‐coating according to the JIS H8615 test. The abrasive wear mechanism of VPS‐sprayed nanocrystalline coatings can be delineated as cutting plus ploughing. For HVOF‐sprayed nanocrystalline coatings the abrasive wear mechanism can be described as cutting plus material delamination.
Search for cerebral G cluster neurons responding to taste stimulation with seaweed in Aplysia kurodai by the use of calcium imaging
Authors: Yoshida Ryusuke , Nagahama Tatsumi 
Published: October 2004

AbstractThe calcium imaging method can detect the spike activities of many neurons simultaneously. In the present experiments, this method was used to search for unique neurons contributing to feeding behavior in the cerebral ganglia of Aplysia kurodai. We mainly explored the neurons whose cell bodies were located in the G cluster and the neuropile region posterior to this cluster on the ventral surface of the cerebral ganglia. When the extract of the food seaweed Ulva was applied to the tentacle‐lip region, many neurons stained with a calcium‐sensitive dye, Calcium Green‐1, showed changes in fluorescence. Some neurons showed rhythmic responses and others showed transient responses, suggesting that these neurons may be partly involved in the feeding circuits. We also identified three motor neurons among these neurons that showed rhythmic fluorescence responses to the taste stimulation. One of them was a motor neuron shortening the anterior tentacle (ATS), and the other two were motor neurons producing lip opening‐like (LOG) and closing‐like (LCG) movements, respectively. Application of the Ulva extract to the tentacle‐lip region induced phase‐locked rhythmic firing activity in these motor neurons, suggesting that these neurons may contribute to the rhythmic patterned movements of the anterior tentacles and lips during the ingestion of seaweed. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 299–314, 2003
Invertebrate D2 type dopamine receptor exhibits age‐based plasticity of expression in the mushroom bodies of the honeybee brain
Authors: Humphries Merideth A. , Mustard Julie A. , Hunter Stacey J. , Mercer Alison , Ward Vernon , Ebert Paul R. 
Published: October 2004

AbstractWe have isolated a cDNA clone from the honeybee brain encoding a dopamine receptor, AmDop2, which is positively coupled to adenylyl cyclase. The transmembrane domains of this receptor are 88% identical to the orthologous Drosophila D2 dopamine receptor, DmDop2, though phylogenetic analysis and sequence homology both indicate that invertebrate and vertebrate D2 receptors are quite distinct. In situ hybridization to mRNA in whole‐mount preparations of honeybee brains reveals gene expression in the mushroom bodies, a primary site of associative learning. Furthermore, two anatomically distinct cell types in the mushroom bodies exhibit differential regulation of AmDop2 expression. In all nonreproductive females (worker caste) and reproductive males (drones) the receptor gene is strongly and constitutively expressed in all mushroom body interneurons with small cell bodies. In contrast, the large cell‐bodied interneurons exhibit dramatic plasticity of AmDop2 gene expression. In newly emerged worker bees (cell‐cleaning specialists) and newly emerged drones, no AmDop2 transcript is observed in the large interneurons whereas this transcript is abundant in these cells in the oldest worker bees (resource foragers) and older drones. Differentiation of the mushroom body interneurons into two distinct classes (i.e., plastic or nonplastic with respect to AmDop2 gene expression) indicates that this receptor contributes to the differential regulation of distinct neural circuits. Moreover, the plasticity of expression observed in the large cells implicates this receptor in the behavioral maturation of the bee. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 315–330, 2003
Developmental changes in the modulation of respiratory rhythm generation by extracellular K+ in the isolated bullfrog brainstem
Authors: Winmill Rachel E. , Hedrick Michael S. 
Published: October 2004

AbstractThis study tested the hypothesis that voltage‐dependent, respiratory‐related activity in vitro, inferred from changes in [K+]o, changes during development in the amphibian brainstem. Respiratory‐related neural activity was recorded from cranial nerve roots in isolated brainstem–spinal cord preparations from 7 premetamorphic tadpoles and 10 adults. Changes in fictive gill/lung activity in tadpoles and buccal/lung activity in adults were examined during superfusion with artificial CSF (aCSF) with [K+]o ranging from 1 to 12 mM (4 mM control). In tadpoles, both fictive gill burst frequency (fgill) and lung burst frequency (flung) were significantly dependent upon [K+]o (r2 > 0.75; p < 0.001) from 1 to 10 mM K+, and there was a strong correlation between fgill and flung (r2 = 0.65; p < 0.001). When [K+]o was raised to 12 mM, there was a reversible abolition of fictive breathing. In adults, fictive buccal frequency (fbuccal), was significantly dependent on [K+]o (r2 = 0.47; p < 0.001), but [K+]o had no effect on flung (p > 0.2), and there was no significant correlation between fbuccal and flung. These data suggest that the neural networks driving gill and lung burst activity in tadpoles may be strongly voltage modulated. In adults, buccal activity, the proposed remnant of gill ventilation in adults, also appears to be voltage dependent, but is not correlated with lung burst activity. These results suggest that lung burst activity in amphibians may shift from a “voltage‐dependent” state to a “voltage‐independent” state during development. This is consistent with the hypothesis that the fundamental mechanisms generating respiratory rhythm in the amphibian brainstem change during development. We hypothesize that lung respiratory rhythm generation in amphibians undergoes a developmental change from a pacemaker to network‐driven process. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 278–287, 2003
The heparan sulfate proteoglycan agrin modulates neurite outgrowth mediated by FGF‐2
Authors: Jung Kim Min , Cotman Susan L. , Halfter Willi , Cole Gregory J. 
Published: October 2004

AbstractAlthough the role of agrin in the formation of the neuromuscular junction is well established, other functions for agrin have remained elusive. The present study was undertaken to assess the role of agrin in neurite outgrowth mediated by the heparin‐binding growth factor basic fibroblast growth factor (FGF‐2), which we have shown previously to bind to agrin with high affinity and that has been shown to mediate neurite outgrowth from a number of neuronal cell types. Using both an established neuronal cell line, PC12 cells, and primary chick retina neuronal cultures, we find that agrin potentiates the ability of FGF‐2 to stimulate neurite outgrowth. In PC12 cells and retinal neurons agrin increases the efficacy of FGF‐2 stimulation of neurite outgrowth mediated by the FGF receptor, as an inhibitor of the FGF receptor abolished neurite outgrowth in the presence of agrin and FGF‐2. We also examined possible mechanisms by which agrin may modulate neurite outgrowth, analyzing ERK phosphorylation and c‐fos phosphorylation. These studies indicate that agrin augments a transient early phosphorylation of ERK in the presence of FGF‐2, and augments and sustains FGF‐2 mediated increases in c‐fos phosphorylation. These data are consistent with established mechanisms where heparan sulfate proteoglycans such as agrin may increase the affinity between FGF‐2 and the FGF receptor. In summary, our studies suggest that neural agrin contributes to the establishment of axon pathways by modulating the function of neurite promoting molecules such as FGF‐2. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 261–277, 2003
Single‐cell analysis reveals cell‐specific patterns of expression of a family of putative voltage‐gated sodium channel genes in the leech
Authors: Blackshaw Susanna E. , Henderson Leslie P. , Malek Julie , Porter Donna M. , Gross Robert H. , Angstadt James D. , Levasseur Sarah M. , Maue Robert A. 
Published: October 2004

AbstractTo understand the molecular basis of nervous system function in the leech, Hirudo medicinalis, we have isolated four novel cDNAs encoding putative voltage‐gated sodium (Na) channel α subunits, and have analyzed the expression of these genes in individual neurons of known function. To begin, degenerate oligonucleotide primers were used in combination with pre‐existing cDNA libraries and reverse transcriptase‐coupled polymerase chain reactions (RT‐PCR). The putative leech Na channel cDNAs (LeNas) exhibit a higher degree of sequence homology to Na channel genes in other species than to voltage‐gated calcium or potassium channel genes, including those expressed in leech. All LeNa cDNAs contain sequences corresponding to regions of functional importance in Na channel α subunits, including the “S4 region” involved in activation, the “pore loops” responsible for ion selectivity, and the “inactivation loop” between the third and fourth domains, though the latter lacks the highly conserved “IFM” motif critical for mammalian Na channel inactivation. Sequences corresponding to important determinants of tetrodotoxin sensitivity are found in some, but not all, LeNa cDNAs, consistent with prior electrophysiological evidence of Na channel heterogeneity in the leech with respect to this toxin. Subsequently, two different sets of isoform‐specific primers and methods of RT‐PCR, including a sensitive, fluorescence‐based “real time” RT‐PCR, were used to analyze LeNa isoform expression in functionally distinct neurons. The results from both approaches were consistent, and not only demonstrated that individual neurons often express more than one LeNa isoform, but also revealed cell‐specific patterns of Na channel isoform expression in the leech nervous system. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 355–371, 2003
Sex differences in rabbit masseter motoneuron firing behavior
Authors: English Arthur W. , Widmer Charles G. 
Published: October 2004

AbstractTo evaluate whether sex differences in the proportions of fibers of different phenotypes in the masseter muscle might be the result of differences in the behavior of their motoneurons, we studied the firing patterns of masseter motoneurons in adult male and female rabbits. Activity in individual motoneurons was determined from high spatial resolution EMG recordings made during cortically evoked rhythmic activation of the masticatory muscles. Although some motoneurons could be said to fire according to slow‐tonic or fast‐phasic patterns, most did not. In both sexes a substantial range of median firing rates and median firing durations was found. In adult males, masseter motoneurons fired more rapidly than those recorded from adult females. No significant sex differences in motoneuron firing duration were found. These results are consistent with the hypothesis that androgen‐induced differences in rabbit masseter muscle fiber phenotype are a reflection of differences in motoneuron firing rate. Whether this effect of androgen is directly upon the motoneurons or is the result of a response of muscle fibers to androgen remains to be investigated. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 331–340, 2003
Examination of Morphological Changes that Affect Gas Permeation through Thermally Damaged Explosives
Authors: Parker Gary R. , Peterson Paul D. , Asay Blaine W , Dickson Peter M. , Perry W. Lee , Henson Bryan F. , Smilowitz Laura , Oldenborg Michael R. 
Published: October 2004

AbstractPhotomicrography and software‐based quantitative image analysis were used to examine microstructural morphology of samples of a plastic bonded explosive, PBX 9501, which had been thermally damaged under varied confinement conditions. Samples were damaged to an advanced state, as would be attained just prior to cook‐off. We observed significant changes in morphology, when compared to pristine material, which contribute to higher gas permeability. Changes included the formation of channels and pores, as well as fracturing of the HMX crystalline component. We discuss both qualitative and quantitative observations of morphology and whether they are likely to affect sensitivity and behavior of PBX 9501.
Physicochemical Parameters of Nitramines Influencing Shock Sensitivity
Authors: van der Heijden Antoine E. D. M. , Bouma Richard H. B. , van der Steen Albert C. 
Published: October 2004

AbstractTNO Prins Maurits Laboratory has actively followed and contributed to the research on the development of insensitive munitions (IM). One of the initial research topics at TNO focused on the improvement of the shape of RDX crystals and its relation to the shock sensitivity. The variation of crystal shape has been studied by crystallization from different solvents and/or by post‐treatment of the crystals. The role of the mean particle size on shock sensitivity was also included in these analyses. The decrease in shock sensitivity is even more pronounced when controlling the internal quality of crystals. In the meantime research has shifted to other energetic materials as well – in particular HMX and CL‐20 – in this way revealing step by step the important physicochemical parameters which play a role in determining the shock sensitivity of formulations containing these types of nitramines. Various characterization techniques, to determine the internal and external quality of crystals will be discussed, and their relation to shock sensitivity in PBXs will be shown. Two different grades of I‐RDX have been subjected to different characterization tests. The objective is to gain more understanding about which of the physicochemical parameters enables one to discriminate between a reduced sensitivity RDX and normal RDX.
Preheating Sensitization of a TATB Composition Part one: Chemical Evolution
Authors: Belmas Robert , Bry Alain , David Claire , Gautier Laurent , Keromnès Anne , Poullain Didier , Thevenot Gilles , Gallic Christian Le , Chenault Jacques , Guillaumet Gérald 
Published: October 2004

AbstractWe analyze the evolution of the sensitivity of a TATB composition after thermal cycles at elevated temperatures. Sensitization due to thermal cycles is of variable magnitude depending on the kind of the second stimulus (mechanical or thermal). In order to investigate the possible mechanisms which govern these phenomena, we perform an extensive study of the evolution of the chemistry and microstructure of our composition and we determine the sensitivity of our explosive to various stimuli after various temperature/duration cycles. This first paper is devoted to the study of TATB chemical evolutions. We present the results obtained for explosive decomposition, furazan generation, gas analyses and solid residue characterization.
A Few Remarks About the Gurney Energy of Condensed Explosives
Authors: Danel Jean‐Francois , Kazandjian Luc 
Published: October 2004

AbstractAfter reconsidering the definition and characteristics of the Gurney energy, we explain some points related to the evaluation and practical use of this quantity. We correct a recently published relationship between the detonation velocity of an explosive and its Gurney energy at infinite expansion. Then, in the framework of cylinder tests, we indicate that the Gurney energy gives only a rough evaluation of experimental results; it can, however, be reasonably used to compare the ability of explosives to accelerate metals. Besides, the value γ=3 classically evoked for the polytropic gamma of the detonation products generally leads to significant errors in the evaluation of the Gurney energy at infinite expansion.
Deflagration of HMX‐Based Explosives at High Temperatures and Pressures
Authors: Maienschein Jon Lee , Wardell Jeffrey Francis , DeHaven Martin Raymond , Black Collin Kevin 
Published: October 2004

AbstractWe measure the deflagration behavior of energetic materials at extreme conditions (up to 520 K and 1 GPa) in the LLNL High Pressure Strand Burner, thereby obtaining reaction rate data for prediction of violence of thermal explosions. The apparatus provides both temporal pressure history and flame time‐of‐arrival information during deflagration, allowing direct calculation of deflagration rate as a function of pressure. Samples may be heated before testing. Here we report the deflagration behavior of several HMX‐based explosives at pressures of 10–600 MPa and temperatures of 300–460 K. We find that formulation details are very important to overall deflagration behavior. Formulations with high binder content (≥15 wt%) deflagrate smoothly over the entire pressure range regardless of particle size, with a larger particle size distribution leading to a slower reaction. The deflagration follows a power law function with the pressure exponent being unity. Formulations with lower binder content (≤10 wt% or less) show physical deconsolidation at pressures over 100–200 MPA, with transition to a rapid erratic deflagration 10–100 times faster. High temperatures have a relatively minor effect on the deflagration rate until the HMX β→δ phase transition occurs, after which the deflagration rate increases by more than a factor of 10.
Communication support system adapted to a user's background knowledge and the topic context
Authors: Sumi Kaoru , Nishida Toyoaki 
Published: October 2004

AbstractThis paper proposes a technique for interpolating the information in a real‐time conversation via computer between a speaker and listener to compensate for differences in the knowledge presumed for the conversation and introduces Telme, a communications support system that uses this technique. The basic premises are that the system infers the context of the current topic based on the terms used by the speaker and infers the listener's degree of knowledge from the listener's questions and a history of operations such as operations for saving certain data. It then supplements the text information of the words dictated by the speaker with information that the listener should require based on those inferences and displays it on the screen. The degree of knowledge is inferred based on the user's conceptual space, which was generated by using multiple conceptual spaces that were created based on the views and opinions of specialists in various fields. The user's conceptual space, which consists of a set of key words having interrelationships, is adapted to the user by functions for inferring those relationships and the user's degree of knowledge through the user's interactions with the computer. This paper proposes a technique, explains basic mechanisms, and reports on and examines application examples and evaluation experiments. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(7): 87–98, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10115