bluuebunny/crossref_metadata_2025 huggingface dataset:
RNA‐Editing 1999
Authors: Knoop Volker , Brennicke Axel
Published: May 2005

In den letzten Jahren wurden immer mehr RNA‐Editingprozesse entdeckt, welche die Abfolge der Nukleotidbausteine einer RNA nach der Abschrift aus dem zugehörigen Gen variieren. Mit der modifizierten Sequenz der Nukleotide ändert sich natürlich auch der Informationsgehalt der RNA ‐ eine Proteinsequenz ist damit in diesen Fällen nicht mehr vollständig aus der DNA‐Sequenz vorhersagbar. Teilweise verändert sich ein RNA‐Molekül durch Editing so sehr, daß der Zusammenhang zwischen RNA und dem entsprechenden Gen in der DNA überhaupt nicht mehr zu erkennen ist.

Inzwischen sind bei vielen verschiedenen Eukaryoten viele Spielarten des RNA‐Editing bekannt. RNA‐Editing kann einzelne oder mehrere Nukleotide einfügen und andere entfernen. Manche reife “richtige” mRNA ist in Trypanosomen nach dem RNA‐Editing mehr als doppelt so lang wie die ursprüngliche Kopie des Gens. In anderen Fällen, insbesondere bei den höheren Eukaryoten von Moos bis Maus, verändern Desaminierungsreaktionen einzelne Basen in ihrer Identität. An spezifischen Orten einer RNA entsteht dabei aus einem Cytidin ein Uridin oder aus einem Adenosin‐ ein Inosinnukleotid. Sind diese Veränderungen in den mRNA‐Editing in den mitochondrialen mRNAs der Pflanzen zur Regel. Hier ist praktisch jede mRNA vom RNA‐Editing betroffen, das die vererbte Information an bis zu 1000 Positionen in den mRNAs korrigiert.
Biologische Folgen der CO2‐Erhöhung
Authors: Körner Christian
Published: May 2005

Die Verbrennung von großteils fossilen Kohlenstoffverbindungen hat seit Beginn der industriellen Revolution einen Anstieg der CO2‐Konzentration in der Atmosphäre von nahezu 30% bewirkt. Aus im Polareis eingeschlossenen Luftblasen ist bekannt, daß sich die Konzentration von 190 ppm (parts per million) zum Höhepunkt der letzten Eiszeit auf etwa 290 ppm um 1800 und heute durchschnittlich 364 ppm erhöht hat ‘;42’. Seit einigen Jahrzehnten ist die Zunahme der CO2‐Konzentration in der Atomosphäre durch kontinuierliche Messungen belegt. Aufgrund der Eisbohrkerne wissen wir auch, daß der CO2‐Pegel im Laufe der letzten 45000 Jahre immer zwischen 1990 und 290 ppm pendelte und nie aus dieser 100 ppm Bandlbreite ausbrach (Abbildung 1).
Selective non-operative management of liver gunshot injuries
Authors: Omoshoro-Jones J A O , Nicol A J , Navsaria P H , Zellweger R , Krige J E J , Kahn D H
Published: May 2005

Background

In contrast to non-surgical treatment of blunt liver trauma, non-operative management (NOM) of liver gunshot injuries (LGSIs) is not widely accepted. This prospective study evaluated an experience of NOM of gunshot wounds to the liver.

Methods

All patients presenting with LGSIs who were haemodynamically stable with no evidence of peritonism underwent a protocol of NOM.

Results

Thirty-three patients (mean age 25 (range 13–50) years) were enrolled over a 36-month period. Fourteen had grade III injuries according to the American Association for the Surgery of Trauma (AAST) classification, whereas 11 and eight patients sustained major (AAST IV/V) and minor (AAST I/II) injuries respectively. NOM was successful in 31 of 33 patients. Two patients required delayed laparotomy for indications unrelated to the hepatic trauma. One patient died from necrotizing fasciitis, which appeared unrelated to the liver injury.

Conclusion

This study demonstrated that, regardless of the grade of liver trauma, NOM is safe and effective in appropriately selected patients with LGSI treated in centres with suitable facilities.
Matrix metalloproteinase 8 (neutrophil collagenase) in the pathogenesis of abdominal aortic aneurysm
Authors: Wilson W R W , Schwalbe E C , Jones J L , Bell P R F , Thompson M M
Published: May 2005

Background

Loss of elastin is the initiating event in abdominal aortic aneurysm (AAA) formation, whereas loss of collagen is required for continued expansion. The elastolytic matrix metalloproteinases (MMPs) 2 and 9 are well described, but the source of excessive collagenolysis remains undefined. The aim of this study was to determine the expression of MMP-8, a potent type I collagenase, in normal aorta and AAA.

Methods

Infrarenal aortic biopsies were taken from 40 AAA and ten age-matched normal aortas. The concentrations of MMP-8 protein and its inhibitors, tissue inhibitor of metalloproteinase (TIMP) 1 and TIMP-2, were quantified by enzyme-linked immunosorbent assay. Immunohistochemistry was used to localize MMP-8 expression.

Results

MMP-8 concentrations were significantly raised in AAA compared with normal aorta (active MMP-8: 4·5 versus 0·5 ng per mg protein, P < 0·001; total MMP-8: 16·6 versus 2·8 ng per mg protein, P < 0·001). Levels of TIMP-1 and TIMP-2 were significantly lower in AAA than in normal aortic samples (TIMP-1: 142·2 versus 302·8 ng per mg protein; P = 0·010; TIMP-2: 9·2 versus 33·1 ng per mg protein, P < 0·001). Immunohistochemistry localized MMP-8 to mesenchymal cells within the adventitia of the aortic wall.

Conclusion

The high concentration of MMP-8 in aortic aneurysms represents a potent pathway for collagen degradation, and hence aneurysm formation and expansion.
Simultaneous determination of myocardial creatine phosphate and adenine nucleotides by reversed‐phase HPLC
Authors: Sanduja Radhika , Ansari G. A. S. , Boor Paul J.
Published: May 2005

An isocratic HPLC system has been developed which allows for the rapid (single run of 20 min) measurement of creatine phosphate (PCr) and adenine nucleotides (ATP, ADP and AMP) in extracts from freeze‐clamped and freeze‐dried myocardial tissues. The separation was achieved at room temperature by using a RP18 column and a dual variable wavelength spectrophotometer, set at 210 and 254 nm. The solvent was 30 mM potassium dihydrogen phosphate, 15 mM tetrabutylammonium hydrogen sulfate, pH 6.7, 19% (v/v) acetonitrile. A distinct separation (confirmed with the retention time of standard sample) of these high energy compounds was achieved. Standard curves were linear. In isolated rat hearts the following values were obtained (μmol/g dry wt, mean ± SEM): ATP 21.5 ± 1.3, ADP 4.6 ± 0.2, AMP 1.5 ± 1.1 and PCr 32.5 ± 1.3; which are consistent with previously published values for high energy compounds in this tissue.
Cysteine uptake and taurine biosynthesis in freshly isolated and primary cultured rat hepatocytes
Authors: Tamura Jun‐ichi , Ohkuma Seitaro , Ida Shuji , Zuo Ping Ping , Kuriyama Kinya
Published: May 2005

Analysis of the uptake and metabolism of [14C]cysteine in rat liver was undertaken using freshly isolated hepatocytes and hepatocytes maintained in primary culture. The uptake of [14C]cysteine by freshly isolated hepatocytes was by means of both saturable and non‐saturable transport systems and the former system was thought to involve facilitated diffusion. The uptake of [14C]cysteine by hepatocytes maintained in primary culture for 24 h also consisted of non‐saturated and saturated transport mechanisms. The magnitude of the saturable transport system in cultured hepatocytes was, however, much greater than that found in freshly isolated hepatocytes, and was considered to be operated by active transport. Both freshly isolated and primary cultured hepatocytes had cysteine sulphinic acid decarboxylase activity, but this enzyme activity in the latter cells was noticeably reduced in comparison with that found in freshly isolated hepatocytes. Hepatocytes maintained in primary culture produced not only radiolabelled taurine, but also radiolabelled cysteine sulphinic acid, hypotaurine and alanine when incubated with [14C]cysteine. The present results indicate that cultured hepatocytes actively transport cysteine as well as metabolizing cysteine to taurine via cysteine sulphinic acid and hypotaurine.
Cytophotometric comparisons of DNA levels in neuronal and glial cells of the cerebellum: A comparative study
Authors: Lee Greta M. , Rasch Ellen M. , Thornthwaite Jerry T.
Published: May 2005

Several cytochemical studies of the DNA content and ploidy status of neuronal cell nuclei in the central nervous system have reported the occurrence of hyperdiploid amounts of DNA in Purkinje cells and suggest the existence of some type of ‘extra’ DNA, the biological significance of which is, as yet, unknown. To explore this phenomenon further, the DNA content of glial and Purkinje cell nuclei was determined in several vertebrate species, using the DNA‐specific fluorochrome 4′,6‐diamidino‐2‐phenylindole (DAPI) to stain isolated cerebellar nuclei for analysis with a single parameter flow cytometer. The Feulgen reaction for DNA was used to stain liver and cerebellar tissue imprints for the measurement of individual nuclei with a Vickers M86 integrating microdensitometer. In both types of analyses, chicken erythrocyte nuclei served as an internal reference standard of 2.5 pg DNA per cell. The mean DNA content of Purkinje cells and glial or granule cells was essentially the same as that found for diploid (2C) non‐neuronal cells, such as hepatocytes, in rainbow trout, Amazon molly fish, salamander (Plethodon), mouse, rat, rabbit, cat, dog, monkey and human. Although Purkinje cell nuclei with 4C DNA levels were found in all of these species, except salamander and rabbit, the frequency of such cells was low (1–7%) and varied with the species. There was a low incidence of Purkinje cell nuclei with interclass DNA amounts in all species examined. Our data show that most neuronal cell nuclei in the cerebellum contain 2C levels of DNA.
Vanadate enhances insulin‐receptor binding in gestational diabetic human placenta
Authors: Al‐Attas Omer S. , Al‐Dagheri Nasser M. , Vigo Noel T.
Published: May 2005

Although vanadium is found abundantly in animal and plant kingdoms its biological effects are not clear. Vanadate compounds have been shown to normalize blood glucose levels in streptozotocin treated rats, enhance glucose oxidation and improve the sensitivity to insulin by enhanced receptor binding in rat adipocytes. The aim of the present study was to investigate the effect of vanadate, at high (0–8 mmol l−1) and low (0–1·0 mmol l−1) physiological concentrations, on [125I]‐insulin binding in the placenta of three groups of pateints, namely from normal (N) controls, gestational diabetics (GDM) and women with risk factors in their medical history for developing diabetes mellitus (RF). Vanadate at low concentrations (0·2–0·6 mmol l−1) enhanced the maximal binding 2‐fold in GDM placenta but only increased (up to 1·2‐fold) the binding slightly at high cncentrations (5 mmol l−1). However with placenta from normal or women at risk, vanadate increased the [125I]‐insulin binding up to 1·2‐fold both at low and high concentrations. Thus it appears that vanadate augements insulin binding in the placenta from women with gestational diabetes mellitus.
Step function technique for estimating data uncertainty in experimental results
Authors: Miah M. J.
Published: May 2005

An 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

Correspondence 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

Techniques 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

The 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

The 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

A 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

Quantum 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

Nach 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

Es 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

Die 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

Bei 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

Bei 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

Nach 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

Nach 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

Sensor 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

Irradiation 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

The 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

An 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

The 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.
The representation of the visual field in the lateral geniculate nucleus of Macaca mulatta
Authors: Malpeli Joseph G. , Baker Frank H.
Published: May 2005

Microelectrode recording techniques were used to investigate the projection of the visual field into the lateral geniculate nucleus (LGN) of Macaca mulatta. The data were used to construct charts plotting visual direction, designated in terms of azimuth and elevation, onto sections of the nucleus cut in coronal, sagittal and horizontal Horsley‐Clarke planes. The projection of the horizontal meridian divides the LGN along its plane of symmetry into a medial‐superior half having negative elevations and a lateral‐inferior half having positive elevations. Elevations become more positive or negative with distance from this plane. Azimuths closest to the vertical meridian are located posteriorly, while the most peripheral azimuths are found at the anterior pole. Two families of surfaces representing visual directions of constant azimuth and elevation are described. Visual field zones of increasing eccentricity are represented serially along the posterior‐anterior axis of the LGN, with the foveal area restricted to the posterior pole and the monocular crescent projecting to the anterior pole. The mapping is completely continuous across the horizontal meridian. The edges of the stacked cell laminae exposed around the periphery of the LGN form an oval band which receives the projection of the perimeter of the contralateral hemifield. The vertical meridian is represented by the posterior two‐thirds of this band, while the periphery of the hemifield projects to the anterior third.

The central visual field out to the optic disc is represented by six cell layers, while the rest of the binocular field projects to four layers only (2 parvocellular and 2 magnocellular). The monocular crescent is represented by one parvocellular and one magnocellular layer. Features associated with the projection column of the optic disc are integrated into the transition from six to four layers. Details of the receptive field topography in the vicinity of the optic disc discontinuities indicate that these gaps are produced by intralaminar mechanisms.

The magnification factor (mm3/steradian) increases monotonically from peripheral visual fields to the foveal center, varying over a range of three decades. This range is intermediate between those derived from data reported in the literature for the retina and the striate cortex. The ratio of LGN magnifications at any two angular eccentricities is a power function, with an exponent of 1.34, of the corresponding ratio of retinal ganglion cell densities. Similarly, the ratio of cortical magnifications (mm2/steradian) at any two eccentricites is a power function, with an exponent of 1.35, of the corresponding ratio of LGN magnifications.
Localization of masticatory motoneurons in the cat and rat by means of retrograde axonal transport of horseradish peroxidase
Authors: Mizuno Noboru , Konishi Akira , Sato Manabu
Published: May 2005

Topographical localization of motoneurons supplying the masticatory muscles was investigated in the cat and rat, utilizing retrograde axonal transport of horseradish peroxidase. Following injection of horseradish peroxidase in each masticatory muscle, motoneurons labelled with peroxidase were seen to be aggregated into a cluster within the motor nucleus of the trigeminal nerve. Such clusters of peroxidase‐labelled motoneurons innervating each masticatory muscle were demarcated more sharply in kittens than in adult animals. The pattern of the nuclear representation of the masticatory muscles was found to be essentially the same in the cat and rat; it could be summarized as follows:

The motor nucleus of the trigeminal nerve could be divided cytoarchitectonically into the dorsolateral and ventromedial divisions; the former was seen in almost the whole rostrocaudal extent of the nucleus, while the latter was localized at the levels of caudal two thirds of the nucleus. In the dorsolateral division, the temporal muscle was represented dorsally and dorsomedially, the masseter muscle ventrolaterally, and the pterygoid muscles ventromedially. In the ventromedial division, the anterior digastric muscle was represented dorso medially, and the mylohyoid muscle ventrolaterally. It was also confirmed that the motoneurons supplying the posterior digastric muscle were localized in the accessory facial nucleus.
Retinal projections in the ringtailed possum Pseudocheirus peregrinus
Authors: Pearson Lyn J. , Sanderson K. J. , Wells R. T.
Published: May 2005

The retinal projections in the ringtailed possum, Pseudocheirus peregrinus were determined using Fink‐Heimer material and autoradiography. At least seven regions in the brain receive retinal projections. These are (1) the suprachiasmatic nucleus of the hypothalamus (2) the dorsal lateral geniculate nucleus (3) the ventral lateral geniculate nucleus (4) the lateral posterior nucleus (5) the pretectum (6) the superior colliculus, and (7) the accessory optic system. The accessory optic system and lateral posterior nucleus receive a contralateral retinal projection only and the other five regions receive a bilateral retinal projection.

The dorsal lateral geniculate nucleus consists of two parts: an outer α division of closely packed cells and an inner β division containing loosely scattered cells. There are no cell layers apparent within the α division in Nissl sections. The autoradiographs and Fink‐Heimer material reveal four concealed laminae within the α division. Lamina 1, which is adjacent to the optic tract and lamina 3 receive a predominantly contralateral input. Laminae 2 and 4 receive a predominantly ipsilateral input. The β segment contains a fifth lamina which receives contralateral retinal input.
Morphological and ultrastructural study of the ventral nerve cord in Branchiobdella pentodonta whitman (Annelida, oligochaeta)
Authors: Vagnetti Daniela , Farnesi Rosalba Maria
Published: May 2005

The ventral nerve cord of Branchiobdella pentodonta consists of paired ganglia containing three different types of neurons, a central neuropil showing characteristic synapses and of an intersegmental apparatus made up of two large lateral connectives and a smaller ventral one. Some remarkable differences exist between the ventral nerve cord and that found in other oligochaetes; these include the presence of a large dorsal blood vessel, two dorsal muscular cells per metamere, and supportive glial cells ventral to the neuropil which have long transverse processes coming into contact with the segmental nerves.
Scanning electron microscopic study of the otolithic organs in the bichir (polypterus bichir) and shovel‐nose sturgeon (scaphirhynchus platorynchus)
Authors: Popper Arthur N.
Published: May 2005

The anatomy and ultrastructure of the sacculus, lagena, and utriculus of the ear of Polypterus bichir and Scaphirhynchus platorynchus were studied using the scanning electron microscope. The otolithic organs each contain a single dense calcareous otolith in close contact with a sensory epithelium (macula). The maculae have sensory hair cell typical of those found in other vertebrates, surrounded by microvilli‐covered supporting cells. The hair cells on each macula are divided into several groups, with all of the cells in each group morphologically polarized in the same direction. The cells of the utricular macula in both species are divided into two opposing groups in a pattern similar to that found in other vertebrates. The saccular and lagenar maculae are located in a single large chamber in both species. In Scaphirhynchus the two maculae are on the same plane, while in Polypterus they are at right angles to one another. The hair cells on the saccular maculae of both species are divided into two oppositely oriented groups. In Scaphirhynchus the cells on the posterior half of the macula are oriented dorsally on the dorsal half of the macula and ventrally on the ventral half. The anterior region of the macula is rotated and the cells of the dorsal and ventral groups are shifted so that they are oriented on the animal's horizontal plane. A similar pattern is found in Polypterus, except that this macula is shaped like a “J” with the vertical portion of the J having horizontal cells and the bottom portion vertical cells. The lagenar maculae in both species have dorsally oriented cells on the anterior side of the macula and ventrally oriented cells on the posterior half of the macula. While these data are not sufficient for clarifying the taxonomic relationship between the two species studied, it is clear that the ears in these species have a number of significant differences from the teleost ear that could have functional and/or taxonomic significance.
The ipsilateral optic pathway to the dorsal lateral geniculate nucleus and superior colliculus in mice with prenatal or postnatal loss of one eye
Authors: Godement Pierre , Saillour Paulette , Imbert Michel
Published: May 2005

The projections, and more particularly the ipsilateral projections, from the retina to the dorsal lateral geniculate nucleus (dlGn) and the superior colliculus have been investigated in adult mice of the C57BL/6J strain after rearing in one of four different conditions: 1) after normal visual experience; 2) after unilateral enucleation at birth; 3) in mice with congenital unilateral anophthalmia (in which only one eye develops) 4) in mice with congenital unilateral microphthalmia (in which only one eye is of reduced size while the other is normal).

In neonatally enucleated and congenitally monocular mice there is an aberrant uncrossed pathway to regions of the dlGn and the superior colliculus which do not normally receive such a projection. This projection is limited in its distribution; in both the neonatally enucaleated and the congenitally monocular animals the uncrossed projection does not reach the lateral and dorsal parts of the dlGn and it only innervates the rostral half of the superior colliculus. The density of the uncrossed pathway in these animals is highest in those regions in which the normal uncrossed pathway terminates. In microphthalmic mice the expansion of the uncrossed pathway is less marked than in monocular mice. In the superior colliculus the aberrant uncrossed projections innervate the stratum griseum superficiale where they are often found distributed in small patches. An intertectal crossing of retinal fibers is described from the contralateral superior colliculus to the deprived ipsilateral superior colliculus.
Lesion‐induced rerouting of hippocampal mossy fibers in developing but not in adult rats
Authors: Laurberg S. , Zimmer J.
Published: May 2005

The organization of the hippocampal mossy fiber system which projects from the granule cells of fascia dentata to the pyramidal cells of the hippocampal regio inferior (CA3) was studied after chronic lesions had been applied to CA3 in neonatal (0–3 day old), 5 and 21 day old, and adult rats. The distribution of terminals was monitored by the histochemical Timm sulphide silver method, and the fibers were demonstrated by the original Nauta silver method.

Complete transections of CA3 in neonatal rats induced a layer of aberrant, infrapyramidal mossy fiber terminals in CA3 up to 1,300 μm septal to the transection followed by a corresponding expansion of the suprapyramidal mossy fiber layer for at least 720 μm. At increasing distance above the lesion, the induced changes moved laterally in CA3, affecting more distal parts of the mossy fibers. Corresponding to the layer of aberrant infrapyramidal terminals were aberrant bundles of mossy fibers, with an abnormally ascending septal course. No aberrant mossy fibers or terminals were induced temporal to the complete transections.

Partial CA3 lesions in neonates induced changes corresponding to those observed after complete transections septal to the lesions. In addition, a layer of aberrant infrapyramidal mossy fiber terminals was induced in CA3 as far as 900 μm temporal to the partial lesions, accompained by an expansion of the suprapyramidal layer. The infrapyramidal terminals were related to aberrant bundles of fibers which followed an abnormally steep, temporal course, from which they in turn leveled off to join the suprapyramidal bundles.

Compared to neonatal lesions, hippocampal transections performed on day 5 induced a slightly less dense layer of aberrant infrapyramidal mossy fiber terminals in CA3, and although a transection on day 21 still induced aberrant infrapyramidal terminals, these were far less abundant than after lesions at day 5. Transections in adult rats induced no such changes at all, and additional denervation of CA3 by simultaneous removal of the commisural projection from the contralateral hippocampus did not have any effect.

The lesion‐induced, but age‐dependent redistribution of mossy fibers to CA3 is discussed in terms of reactive reinnervation following partial deafferentation, and compensatory sprouting and rerouting due to pruning‐like effects of the lesions. A rerouting of developing, not fully matured mossy fibers is found to be most likely: Deprived of normal target areas, the fibers have been forced to grow in abnormal directions, ending up hyperinnervating adjacent, accessible levels through the formation of aberrant infrapyramidal terminals and expansion of the suprapyramidal zone.
The pregeniculate nucleus of the monkey (Macaca mulatta). I. A. study at the light microscopy level
Authors: Babb Richard S.
Published: May 2005

A study of the pregeniculate nucleus of the monkey (Macaca mulatta), in Klüver‐Barrera‐stained, and Golgi‐impregnated material confirmed, with reservations, that the nucleus is bilaminar. The inner lamina extends anterior to posterior as a compact band of neuropil within the optic tract, passing from a dorsomedial position to occupy a more dorsolateral position with respect to the lateral geniculate nucleus. The neuropil of this lamina is formed from a plexus of very fine fibers, many having varicosities, which appear to make contact with dendrites. The outer lamina appears to be formed that part of the thalamic reticular nucleus that is apposed to the lateral geniculate nucleus.

Three types of neurons were observed in the nucleus: Type I are found only in the inner lamina; they have small (12–14 μm) spheroid somata with thin dendrites having terminal arborizations formed by long protrusions and axons exhibiting varicosities. Type II neurons in contrast are found only in the outer lamina; their cell bodies are large (21 by 33 μm to 26 by 37 μm) and polygonal, contain much Nissl substance, and exhibit thick, relatively spine‐free dendrites. Type III neurons, which are the most common, are found in both laminae; they have medium‐sized 13 by 27 μm to 19 by 40 μm ellipsoid somata containing moderate amounts of Nissl substance and exhibiting well‐developed spine‐bearing dendrites. Since the axon of the type I neuron impregnates and is found only within the nucleus, this cell is considered to be an intrinsic neuron; on the other hand, types II and III are judged to be principal neurons, as their axons do not impregnate.