bluuebunny/crossref_metadata_2025_split huggingface dataset:
Step function technique for estimating data uncertainty in experimental results
Authors: Miah M. J. 
Published: May 2005

AbstractAn additive model is used to express the observed value of a sample characteristic as the sum of the true sample characteristic and a value of the data collection error, commonly known as experimental error. The data uncertainty of the experimental results (or of a survey data set) is defined as the expected squared error. The expected squarred error may change with the sample characteristic, e.g. the error moment could be concentration‐dependent. The relationship between the error variance and the analyte concentration may not be very distinct. In such a case the data transformation to stabilize the error moments may not be appropriate. A step function is proposed as an alternative way to represent the second moment of the error. The data uncertainty is defined as the weighted average of the step values of the second raw moment of the error, using the appropriate proportions of the routine samples as weights. The data uncertainties associated with the different data collection stages were evaluated by using regional soil survey data.
Correspondence analysis used in the evaluation of lakewater chemistry in the Adirondacks
Authors: Rhodes Hannan Rasmussen , Myers Donald E. 
Published: May 2005

AbstractCorrespondence analysis (CA) was applied to lakewater data in order to study the effects of acidic deposition on the geochemical composition of lakes in the Adirondacks. The lake chemistry data analyzed were taken from the Eastern Lake Survey ‐ Phase I (ELS‐I) conducted by the U.S. Environmental Protection Agency. CA was used to identify ‘outlying’ lake samples as well as ‘superflous’ and ‘unresolved’ analytes. Correlational relationship among analytes were also examined.
Likelihood techniques for interlaboratory calibration in the national stream survey
Authors: Permutt Thomas , Edland Steven D. , Moezzi Mithra , Grosser Stella C. 
Published: May 2005

AbstractTechniques for testing for and estimating relative bias between two laboratories are developed and applied to a survey of the chemistry of streams in the United States. The design of the quality assurance program allows estimation of linear corrections for bias as well as testing of the hypothesis of linearity. Designs of this type are useful, but improvements are suggested.
CoI‐ and Co0‐Bipyridine Complexes Obtained by Reduction of CoBr2bpy: Electrochemical Behaviour and Investigation of Their Reactions with Aromatic Halides and Vinylic Acetates
Authors: Polleux Laurent , Labbé Eric , Buriez Olivier , Périchon Jacques 
Published: May 2005

AbstractThe electrochemical behaviour of CoBr2bpy (bpy=2,2′‐bipyridine) catalyst precursor in acetonitrile has been studied, revealing its possible reduction into the corresponding CoI and Co0 complexes. These low‐valent cobalt species appear to be stable on the time scale of cyclic voltammetry. In the presence of aromatic halides, both complexes undergo oxidative addition, the latter Co0 species allowing the activation of poorly reactive aromatic chlorides. The arylcobaltIII and arylcobaltII obtained are reduced at the same potential as the original CoII and CoI complexes, respectively, resulting in the observation of overall ECE mechanisms in both cases. The electrochemical study shows that vinylic acetates competitively react with electrogenerated Co0 species, leading to a labile complex. Preparative scale electrolyses carried out from solutions containing aromatic halides (ArX), vinyl acetate (vinylOAc) and a catalytic amount of CoBr2bpy lead to a mixture of biaryl (Ar‐Ar) and arene (ArH) as long as the potential is set on the plateau of the CoII ⇄ CoI reduction wave. The coupling product (Ar‐vinyl) is formed only if the electrolysis is performed on the plateau of the CoI/Co0 reduction wave. A mechanism is proposed for the overall cobalt‐catalyzed coupling reaction between aromatic halides and allylic acetates.
New Homoleptic Organometallic Derivatives of Vanadium(III) and Vanadium(IV): Synthesis, Characterization, and Study of Their Electrochemical Behaviour
Authors: Alonso Pablo J. , Forniés Juan , García‐Monforte M. Angeles , Martín Antonio , Menjón Babil 
Published: May 2005

AbstractThe arylation of [VCl3(thf)3] with LiRCl, where RCl is a polychlorinated phenyl group [C6Cl5, 2,4,6‐trichlorophenyl(tcp), or 2,6‐dichlorophenyl (dcp)] gives four‐coordinate, homoleptic organovanadium(III) derivatives with the formula [Li(thf)4][VIII(RCl)4] (RCl=C6Cl5 (1), tcp (2), dcp (3)). The anion [VIII(C6Cl5)4]− has an almost tetrahedral geometry, as observed in the solid‐state structure of [NBu4][V(C6Cl5)4] (1′) (X‐ray diffraction). Compounds 1–3 are electrochemically related to the neutral organovanadium(IV) species [VIV(RCl)4] (RCl=C6Cl5 (4), tcp (5), dcp (6)). The redox potentials of the VIV/VIII semisystems in CH2Cl2 decrease with decreasing chlorination of the phenyl ring (E1/2=0.84 (4/1), 0.42 (5/2), 0.25 V (6/3)). All the [VIV(RCl)4] derivatives involved in these redox couples could also be prepared and isolated by chemical methods. The arylation of [VCl3(thf)3] with LiC6F5 also gives a homoleptic organovanadium(III) compound, but with a different stoichiometry: [NBu4]2[VIII(C6F5)5] (7). In this five‐coordinate species, the C6F5 groups define a trigonal bipyramidal environment for the vanadium atom (X‐ray diffraction). EPR spectra for the new organovanadium compounds 1–6 are also given and analysed in terms of an elongated tetrahedral structure with C2v local symmetry. It is suggested that the RCl groups exert a protective effect towards the vanadium centre.
Water Superstructures within Organic Arrays; Hydrogen‐Bonded Water Sheets, Chains and Clusters
Authors: Oxtoby Neil S. , Blake Alexander J. , Champness Neil R. , Wilson Claire 
Published: May 2005

AbstractA strategy for encouraging the formation of extended water arrays is presented, in which molecules that contain a 1,4‐dihydroquinoxaline‐2,3‐dione core are used as supramolecular hosts for the accommodation of guest water molecules and arrays. These molecules were selected as they contain a hydrophilic oxalamide‐based “terminus” that allows water molecules to hydrogen‐bond to the host organic molecules as well as to each other. The host molecules also contain a hydrophobic “end” based upon an aromatic ring, which serves to encourage the formation of discrete water clusters in preference to three‐dimensional networks, as the water molecules cannot form strong hydrogen bonds with this part of the molecule. A systematic study of several hydrated structures of four organic molecules based on 1,4‐dihydroquinoxaline‐2,3‐dione (qd) is discussed. The organic molecules, qd, 6‐methyl‐1,4‐dihydroquinoxaline‐2,3‐dione (mqd), 6,7‐dimethyl‐1,4‐dihydroquinoxaline‐2,3‐dione (dmqd) and 1,4‐dihydrobenzo[g]quinoxaline‐2,3‐dione (Phqd), act as supramolecular crystal hosts for the clusters of water, with zero‐, one‐ and two‐dimensional arrays of water being observed. The hydrogen bonding in the structures, both within the water clusters and between the clusters and organic molecules, is examined. In particular, the structure of dmqd⋅6 H2O contains a two‐dimensional water sheet composed of pentagonal and octagonal units. Phqd⋅3 H2O forms a hydrophilic extended structure encouraging the formation of one‐dimensional chains consisting entirely of water. Both qd⋅2 H2O and dmqd⋅2 H2O can be considered to form one‐dimensional chains, but only by utilising bridging carbonyl groups of the oxalamide moieties to form the extended array; if only the water is considered, zero‐dimensional water tetramers are observed. The remaining hydrated structures, [Na+dmqd−]dmqd⋅H2O, dmqd⋅1/3H2O and mqd⋅1/2H2O, all contain discrete water molecules but do not form extended water structures.
Chemo‐ and Periselectivity in the Addition of [OsO2(CH2)2] to Ethylene: A Theoretical Study
Authors: Hölscher Markus , Leitner Walter , Holthausen Max C. , Frenking Gernot 
Published: May 2005

AbstractQuantum chemical calculations by using density functional theory at the B3LYP level have been carried out to elucidate the reaction course for the addition of ethylene to [OsO2(CH2)2] (1). The calculations predict that the kinetically most favorable reaction proceeds with an activation barrier of 8.1 kcal mol−1 via [3+2] addition across the OOsCH2 moiety. This reaction is −42.4 kcal mol−1 exothermic. Alternatively, the [3+2] addition to the H2COsCH2 fragment of 1 leads to the most stable addition product 4 (−72.7 kcal mol−1), yet this process has a higher activation barrier (13.0 kcal mol−1). The [3+2] addition to the OOsO fragment yielding 2 is kinetically (27.5 kcal mol−1) and thermodynamically (−7.0 kcal mol−1) the least favorable [3+2] reaction. The formal [2+2] addition to the OsO and OsCH2 double bonds proceeds by initial rearrangement of 1 to the metallaoxirane 1 a. The rearrangement 1→1 a and the following [2+2] additions have significantly higher activation barriers (>30 kcal mol−1) than the [3+2] reactions. Another isomer of 1 is the dioxoosmacyclopropane 1 b, which is 56.2 kcal mol−1 lower in energy than 1. The activation barrier for the 1→1 b isomerization is 15.7 kcal mol−1. The calculations predict that there are no energetically favorable addition reactions of ethylene with 1 b. The isomeric form 1 c containing a peroxo group is too high in energy to be relevant for the reaction course. The accuracy of the B3LYP results is corroborated by high level post‐HF CCSD(T) calculations for a subset of species.
Untersuchungen über Dampfdruckkurven und kritische Daten einiger technisch wichtiger organischer Substanzen
Authors: Glaser Fritz , Rüland Heinz 
Published: May 2005

AbstractNach Aufnahme von sieben Eickurven wurden 36 neue Dampfdruckkurven von Substanzen aufgenommen, deren Dampfdruckdaten zumindest im Bereich zwischen Siedepunkt und kritischer Temperatur nicht der Literatur entnommen werden konnten. Die experimentell bestimmten Werte wurden nach der van der Waalsschen Dampfdruckgleichung graphisch dargestellt. Für die meisten Substanzen konnte aus diesen graphischen Darstellungen der kritische Punkt experimentell bestimmt werden. Wo dies nicht möglich war, wurde er über die molare Verdampfungswärme und mit Hilfe des Theorems der übereinstimmenden Zustände berechnet. Soweit die Substanzen die Riedelsche Dampfdruckformel erfüllten, wurde der spezifische kritische Parameter αk berechnet. Schließlich wurden die Dampfdruckformel von van der Waals und L. Riedel miteinander verglichen.
Vorausberechnung katalytischer Strömungsreaktionsöfen II. Vorausberechnung eines autothermen Reaktionsofens
Authors: Paszthory E. , Schügerl K. , Bakos N. 
Published: May 2005

AbstractEs wird mit Hilfe reaktionstechnischer und wärmetechnischer Daten, die im Teil I nach einer neuen Methode ermittelt wurden, ein autothermer Reaktionsofen für die Dampfphase‐Hydrierung von Acetaldehyd vorausberechnet, welcher eine fünfzigfache Leistung des Laboratoriums‐Reaktionsofens aufweist. Die Zuverlässigkeit der Vorausberechnung wird an den Ergebnissen dieses autothermen Modell‐Reaktionsofens unter Anwendung der in dem Teil I mitgeteilten Methode geprüft. Auch an diesem autothermen Reaktor von 250 I werden die axialen Temperatur‐ und Umsatzverteilungen in Abhängigkeit von Strömungsgeschwindigkeit und Temperatur bestimmt und daraus annähernde kinetische Daten ermittelt. Die gute Übereinstimmung der scheinbaren kinetischen Daten am Laboratoriums‐Reaktionsofen und dem halbtechnischen autothermen Reaktionsofen sowie der vorausberechneten und gemessenen axialen Umsatzverteilungen beweisen die Anwendbarkeit der mitgeteilten Methoden.
Untersuchungen zum Stoffübergang bei der Teilkondensation von Gemischdämpfen
Authors: Kirschbaum Emil , Tröster E. 
Published: May 2005

AbstractDie Trennwirkung eines Dephlegmators wird maßgeblich vom Verhältnis aus Kondensatbelastung und Stoffübergangszahl bestimmt. Sie läßt sich für technisch übliche Betriebsbedingungen vorausberechnen, wenn die Stoffübergangszahl bekannt ist. Es sind daher umfangreiche Untersuchungen unternommen worden, die zu einer allgemein gültigen Beziehung zwischen wenigen dimensionslosen Kennzahlen führten, aus der die Stoffübergangszahlen abhängig von den Stoffwerten und den konstruktiven Größen zu den jeweiligen Betriebszuständen ermittelt werden können.
Verfahren zur Herstellung von 1‐Methoxybuten‐(1)‐in‐(3)
Authors: Scharein G. 
Published: May 2005

AbstractBei der Herstellung von Acetylen im elektrischen Lichtbogen fällt bei der Reinigung des Acetylens ein Gemisch von höheren Acetylenen an. Es wird ein Verfahren beschrieben, mit dem man aus diesem diacetylen‐haltigen Gemisch gefahrlos eine 50proz. Lösung vom Methoxybutenin durch Anlagerung von Methanol herstellen kann. Die Umsetzung verläuft in Gegenwart von 3% Kaliumhydroxid bei 100°C und 5 atü. Seit 1965 ist eine Anlage mit einer Monatskapazität von 60 t Methoxybutenin‐Lösung in Betrieb.
Probleme bei der industriellen Anwendung der Zerstäubungstrocknung
Authors: Kessler H. G. 
Published: May 2005

AbstractBei industriellen Zerstäubungstrocknern sind die Schwierigkeiten oft nicht im eigentlichen Trocknungsvorgang begründet, sondern in den Neben‐ und Hilfseinrichtungen. Dies gilt besonders, seit man auch eingedickte Flüssigkeiten der Zerstäubungstrocknung zugänglich macht. Eine Wirtschaftlichkeitsbetrachtung zeigt, daß Zerstäubungstrockner erst von einer bestimmten Mindestgröße an mit geringeren Kosten arbeiten als Walzentrockner. Durch besondere Maßnahmen bei der Produkteinspeisung und Zerstäubung lassen sich Form und Abmessungen der getrockneten Partikel in der gewünschten Weise beeinflussen. Bei der Gasführung wird Gleichstrom bevorzugt. Besondere Aufmerksamkeit erfordern die Sicherheits‐ und Regeleinrichtungen.
Stofftransport bei der Elektrolyse mit Gasrührung
Authors: Adam E. , Venczel J. , Schalch E. 
Published: May 2005

AbstractNach einer Beschreibung der elektrolytischen Gasentwicklung, die in drei Schritten (Keimbildung, Wachstum und Ablösen der Blasen) erfolgt, wird eine Übersicht über Messungen der Stofftransportgeschwindigkeit an gasentwickelnden Elektroden gegeben. Bei H2‐Entwicklung ist die effektive Diffusionsschichtdicke δNumgekehrt proportional der Wurzel der Gasentwicklungsgeschwindigkeit. Bei Stromdichten von etwa 1 A/cm2beträgt δNnur einige μm. Es werden Schlußfolgerungen für die Praxis und einige Anwendungsbeispiele der experimentell erhaltenen Korrelationen beschrieben sowie ein theoretisches Modell für den Stofftransport bei Gasentwicklung diskutiert. Zum Vergleich wurden auch die Stofftransportgeschwindigkeiten bei Einleiten von Fremdgas in die Zelle gemessen. Es ergaben sich hier keine so hohen Stoffübergangszahlen wie bei Gasentwicklung an der Elektrode; sie sind jedoch um eine Größenordnung höher als bei natürlicher Konvektion.
Zur Konzentrationsstabilität des isothermen Reaktors bei der kontinuierlichen Emulsionspolymerisation von Styrol
Authors: Gerrens Heinz , Kuchner Karl , Ley Gregor 
Published: May 2005

AbstractNach einer Theorie von Matsuura und Kato können in einem isotherm und kontinuierlich betriebenen idealen Rührkessel ein instabiler und zwei stabile stationäre Betriebszustände entstehen, wenn die untersuchte Reaktion autokatalytischen Charakter hat. Die Emulsionspolymerisation von Styrol zeigt bei bestimmten Bedingungen eine starke Selbstbeschleunigung durch den Trommsdorff‐Effekt. Bei kontinuierlicher Reaktion in einer dreistufigen Rührkesselkaskade wurden experimentell sechs stabile stationäre Betriebspunkte der Einzelreaktoren und drei stabile Betriebszustände der Gesamtkaskade gefunden. Ihre Daten stimmen mit den Werten überein, die nach der diskontinuierlich gemessenen Zeit‐Umsatz‐Kurve theoretisch zu erwarten sind. Kurzfristige Erhöhung der Monomerenkonzentration läßt einen der Reaktoren vom einen zum anderen stabilen Betriebspunkt übergehen. Theoretisch sind bei einer Kaskade mitnReaktoren maximal (n+ [n(n+ 1)]/2) stabile undnlabile Betriebspunkte der Einzelreaktoren sowie (n+ 1) stabile Betriebszustände der Gesamtkaskade möglich.
Sensortechnik in der Chemie – Status und Trend
Authors: Gilles Ernst‐Dieter , Nicklaus Eberhard , Polke Martin 
Published: May 2005

AbstractSensor technology in the chemical process industries – status and trends. Sensor technology is used in chemical process industries to provide information on product and process properties. The computerized handling of this information has altered the requirements for sensor systems. New production methods and the automation of existing processes lead to new tasks for sensor systems. The advancement of sensor technology is proceeding on a broad front and in small steps, also exploiting the potential of microelectronics. Model‐based measuring methods utilizing a priori knowledge about the process may substantially increase the information gain.
Lebensmittelbestrahlung
Authors: Schubert Helmar , Ehlermann Dieter 
Published: May 2005

AbstractIrradiation of food. Processing of food with ionizing radiation is a method suitable to enhance shelf‐life and hygienic quality. Up to a dose of 10 kGy the method is considered wholesome. In many countries the practical use of food irradiation is increasing, however, in the Federal Republic of Germany the process is strictly forbidden. Applications and methods for radiation processing of food are compiled, limits and prospects are explained, and advantages and disadvantages are compared with traditional methods. Identification of irradiated foods and dosimetry and process control for radiation processing of food are areas where further research is needed. Continuous processing of particulate foods in bulk is an application where electron accelerators might be profitable. Beam parameters and velocity distribution of food particles in the treatment area can be matched for an effective result. Thus, dose distribution can be adjusted for homogeneous treatment and at the same time radiation energy is absorbed almost completely. An example of an experimental plant for radiation processing of grain und spices is shown. Decontamination of spices by radiation processing is an alternative to chemical fumigation, which now is widely forbidden.
An autoradiographic study of complementary laminar patterns of termination of afferent fibers to the olfactory cortex
Authors: Price Joseph L. 
Published: May 2005

AbstractThe afferent projections to the olfactory cortical areas from the olfactory bulb and the prepiriform cortex have been studied in the rat, using the autoradiographic method for demonstrating axonal connections. In order to relate closely the results of these experiments to the structure of the olfactory cortical areas, the cytoarchitectonic characteristics of these areas have also been described.The olfactory cortical areas, which receive a direct input from the olfactory bulb, include the anterior olfactory nucleus, the ventral portion of the tenia tects, the olfactory tubercle, the prepiriform cortex, the nucleus of the lateral olfactory tract, the cortical amygdaloid nucleus, and the lateral entorhinal area. All of these areas are composed primarily of pyramidal cells and have three basic layers: a superficial plexiform layer containing the apical dendrites of the pyramidal cells (layer I), a pyramidal cell layer (layer II), and a deeper polymorphic cellular layer (layer III). In each area layer I may be divided into a superficial portion (IA) and a deeper portion (IB).The autoradiographic experiments have shown that all of the olfactory cortical areas receive projections from the prepiriform cortex as well as from the olfactory bulb, and that these two projections have complementary laminar patterns of termination which are the same in every area. Throughout the olfactory cortex the fibers from the olfactory bulb terminate exclusively in layer IA, in relation to the distal segments of the apical dendrite of the pyramidal cells, whereas the fibers from the prepiriform cortex terminate in layer IB, in relation to more proximal segments of the apical dendrites, and also in layer III. The boundary between the two projections within layer I is very sharp, with minimal overlap. In contrast to this precise laminar organization, there is little evidence for a topographical organization within these Projections.
Brain mechanisms and feeding behavior in the pigeon (Columba livia) II. Analysis of feeding behavior deficits after lesions of quinto‐frontal structures
Authors: Zeigler H. Philip , Karten Harvey J. 
Published: May 2005

AbstractAn analysis of the deficits produced by lesions of quinto‐frontal structures (PrV, QFT, NB) in the pigeon was carried out, using a variety of measures of hunger and thirst. The results may be summarized as follows:
In pigeons maintained under ad‐libitum conditions lesions of PrV, QFT and NB are followed by a period in which responsiveness to food is abolished or significantly reduced.
Lesions of PrV and NB impair the performance of the consummatory response of eating by disrupting the neuro‐sensory control of mandibulation.
Lesions of PrV and NB abolish an operant key‐pecking response reinforced with food for periods ranging from a few days to several weeks.
No effects of quinto‐frontal lesions upon either operant or consummatory measures of thirst were observed.
We conclude that quinto‐frontal structures mediate both sensorimotor and motivational processes involved in the control of feeding behavior in the pigeon and that these two functions may be experimentally dissociated. Our results are discussed in relation to previous studies of the sensory and neural control of hunger in birds and mammals.
Differential projections of ordinary lateral line receptors and electroreceptors in the gymnotid fish, Apteronotus (Sternarchus) albifrons
Authors: Maler L. , Finger T. , Karten H. J. 
Published: May 2005

AbstractThe gymnotid acousticolateral area contains both anterior and posterior lobes. The posterior lobe is closely associated with the lobus caudalis of the cerebellum. Ordinary lateral line receptors are represented in the anterior lobe, while electroreceptors are represented in the posterior lobe. As is the case in mormyrids, there is an extensive projection of parallel fibers from the lobus caudalis of gymnotids to the dorsal portion of the posterior lobe molecular layer. There is very little information on input to the lobus caudalis; one possible input is from the anterior lobe.