bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic parameters for step and flash imprint lithography photopolymerization
Authors: Dickey Michael D. , Willson C. Grant
Published: October 2005

Step and Flash Imprint Lithography (SFIL) is a high‐resolution, yet low‐cost nanopatterning technique that employs an acrylate‐based, free‐radical photo‐polymerization to replicate a patterned template onto a substrate. Modeling the photo‐polymerization requires knowledge of the values of several reaction parameters, which are unique to the acrylate formulation used in SFIL. The values of these parameters were experimentally determined for use in a previously described kinetic model. The rate coefficient for initiation, kI, was determined by measuring the absorbance spectrum of the initiator, Darocur® 1173, and convolving it with the intensity spectrum from the irradiation source. The reaction coefficients kp and kt were measured using the dark polymerization method. The experimental values of both parameters were then mathematically modeled to reflect the changes that occur as a function of conversion. Measuring the kinetic parameters provides insight into the fundamental steps involved in the polymerization. © 2005 American Institute of Chemical Engineers AIChE J, 2006
Association of the putative susceptibility gene, transient receptor potential protein melastatin type 2, with bipolar disorder
Authors: Xu Chun , Macciardi Fabio , Li Peter P. , Yoon Il‐Sang , Cooke Robert G. , Hughes Bronwen , Parikh Sagar V. , McIntyre Roger S. , Kennedy James L. , Warsh Jerry J.
Published: October 2005

Disturbed intracellular calcium (Ca2+) homeostasis has been implicated in bipolar disorder (BD). Reduced mRNA levels of the transient receptor potential Ca2+ permeable channel melastatin type 2, TRPM2, in B lymphoblast cell lines (BLCL) from bipolar I disorder (BD‐I) patients showing elevated basal intracellular Ca2+ ([Ca2+]B), an index of altered intracellular Ca2+ homeostasis, along with its location within a putative BD susceptibility locus (21q22.3), implicates the involvement of this gene in the Ca2+ abnormalities and the genetic diathesis to BD. We tested this hypothesis by examining the association of selected single nucleotide polymorphisms (SNPs) and their haplotypes, spanning the TRPM2 gene, with BD and BLCL [Ca2+]B, in a case control design. The 5′ TaqMan SNP assay was used to detect selected SNPs. BLCL [Ca2+]B was determined by ratiometric fluorometry. SNP rs1618355 in intron 18 was significantly associated with BD as a whole (P < 7.0 × 10−5; odds ratio (OR) = 2.60), and when stratified into BD‐I (P < 7.0 × 10−5, OR = 2.48) and BD‐II (P = 7.0 × 10−5, OR = 2.88) subgroups. In addition, the alleles of the individual SNPs forming a seven marker at‐risk haplotype were in excess in BD (12.0% in BD vs. 0.9% in controls; P = 2.3 × 10−12). A weak relationship was also detected between BLCL [Ca2+]B and TRPM2 SNP rs1612472 in intron 19. These findings suggest genetic variants of the TRPM2 gene increase risk for BD and support the notion that TRPM2 may be involved in the pathophysiology of BD. © 2005 Wiley‐Liss, Inc.
Investigation of the Mechanism of Resistance to Third‐Generation Cephalosporins by Class C β‐Lactamases by Using Chemical Complementation
Authors: Carter Brian T. , Lin Hening , Goldberg Shalom D. , Althoff Eric A. , Raushel Jessica , Cornish Virginia W.
Published: October 2005

The widespread use of antibiotics to treat bacterial infections has led to the continuing challenge of antibiotic resistance. For β‐lactam antibiotics, the most common form of resistance is the expression of β‐lactamase enzymes, which inactivate the antibiotics by cleavage of the β‐lactam core. In this study, chemical complementation, which is a general method to link the formation or cleavage of a chemical bond to the transcription of a reporter gene in vivo, was employed in combination with combinatorial mutagenesis to study the mechanism by which the class C β‐lactamase P99 might evolve resistance to the commonly administered third‐generation cephalosporin cefotaxime. The chemical complementation system was first shown to be able to distinguish between the wild‐type (wt) class C β‐lactamase P99 and the clinically isolated extended‐spectrum class C β‐lactamase GC1 in the presence of cefotaxime. The system was then employed to evaluate the activity of mutants of wt P99 towards cefotaxime. A number of single‐point mutations at position 221 (Tyr in wt P99) were identified that conferred resistance towards inhibition by cefotaxime, with as much as a 2000‐fold increase in kcat and a 100‐fold increase in kcat/KM (kcat=the rate of catalysis; KM=the Michaelis constant), as compared to those of the wt enzyme. Finally, the chemical complementation system was employed in a high‐throughput screen to identify a number of mutants of P99 that have multiple mutations around the substrate‐binding pocket that increase resistance towards cefotaxime inhibition. The catalytic turnover of cefotaxime by the most active mutant identified was 5500 times higher than that of the wt P99. The resistant mutants suggest a mechanism by which a number of mutations can confer resistance by increasing the flexibility of the Ω loop and altering the positioning of residue 221. Thus, as illustrated in this study, chemical complementation has the potential to be used as a high‐throughput screen to study a wide range of enzyme–drug interactions.
Cover Picture: Light‐Induced Formation of G‐Quadruplex DNA Secondary Structures (ChemBioChem 11/2005)
Authors: Mayer Günter , Kröck Lenz , Mikat Vera , Engeser Marianne , Heckel Alexander
Published: October 2005

The cover picture shows in the magnifying lens oligodeoxynucleotides that have been modified with a photolabile group, represented as a green star. This temporary modification blocks the interaction properties of the respective nucleobase. One of these "caged oligodeoxynucleotides" has just been hit with light, thus removing the modification. The unmodified oligodeoxynucleotide can now fold into the active conformation—‐in this case a G‐quadruplex. The background suggests possible applications. Confocal microscopy can be used to apply light with high spatiotemporal control and allow the triggering of biologically active oligodeoxynucleotides; in the future maybe even in individual cells. For more details, see the communication by Mayer, Heckel, et al. on p. 1966 ff.
Spectroscopic Studies of Water‐Soluble Porphyrins with Protein Encapsulated in Bis(2‐ethylhexyl)sulfosuccinate (AOT) Reverse Micelles: Aggregation versus Complexation
Authors: Andrade Suzana M. , Costa Sílvia M. B.
Published: October 2005

We have investigated the interaction of two water‐soluble free‐base porphyrins (negatively charged meso‐tetrakis(p‐sulfonatophenyl)porphyrin sodium salt (TSPP) and positively charged meso‐tetrakis(N‐methylpyridinium‐4‐yl)porphyrin (TMpyP)) with two drug‐carrier proteins (human serum albumin (HSA) and β‐lactoglobulin (βLG)) in bis(2‐ethylhexyl)sulfosuccinate (AOT)/isooctane/water reverse micelles (RM) by using steady‐state and transient‐state fluorescence spectroscopy. TSPP exhibited a complex pattern of aggregation on varying the RM size and pH in the absence of the protein: at low ω0 (the ratio of water concentration to AOT concentration, the emission of H‐aggregates prevails under acidic or neutral “pHext” conditions. Upon formation of the water‐pool, J‐aggregates and monomeric diacid species dominate at low “pHext” but only monomer is detected at neutral “pHext”. The aggregation number increases with ω0 and the presence of the protein does not seem to contribute to further growth of the aggregate. The presence of protein leads to H‐deaggregation but promotes J‐aggregation up to a certain protein/porphyrin ratio above which, complexation with the monomer bound to a hydrophobic site of the protein prevails. The effective complex binding constants are smaller than in free aqueous solution; this indicates a weaker binding in these RM probably due to some conformational changes imposed by encapsulation. Only a weak quenching of TMpyP fluorescence is detected due to the presence of protein in contrast to the negative porphyrin.
Electro‐ and Magnetocommunication in [5,5]Ditrovacenyls, [(η7‐C7H7)V(η5‐C5H4‐X‐η5‐C5H4)V(η7‐C7H7)], Mediated by the Spacers X=(Z)CHCH, (E)CHCH, >CCH2, CH2CH2, and CH2
Authors: Elschenbroich Christoph , Plackmeyer Jörn , Nowotny Mathias , Behrendt Andreas , Harms Klaus , Pebler Jürgen , Burghaus Olaf
Published: October 2005

Five new paramagnetic dinuclear complexes containing [5]trovacenyl groups, (η7‐C7H7)V(η5‐C5H4), have been prepared and characterized, including by single‐crystal X‐ray diffraction. As intervening spacers, ethenediyl units in the geminal and vicinal (Z)‐ and (E)‐bridging modes as well as methanediyl and ethanediyl units have been included with the aim of studying their propensity to transmit electric and magnetic information. It is found that redox splitting of consecutive electron‐transfer steps is resolved for reduction (0→1−→2−) only, unsaturation of the C2 bridge not being requisite, since the CH2CH2 spacer also gives rise to a small redox splitting. Magnetic communication is quantified in terms of the exchange coupling constant J, accessible from the EPR hyperfine pattern in solution and from magnetic susceptometry in the solid state. The results obtained from these methods generally differ; this fact is not surprising in view of conformational differences in the respective states of aggregation. It is concluded that orientation‐dependent mechanisms of spin–spin interactions (π‐orbital overlap, hyperconjugation) contribute extensively although, as implied by sizeable J values for CH2 and C2H4 linked di[5]trovacenyl groups, coupling mediated by the σ‐orbital chain must also be considered.
Controlled Nanozeolite‐Assembled Electrode: Remarkable Enzyme‐Immobilization Ability and High Sensitivity as Biosensor
Authors: Yu Tao , Zhang Yahong , You Chunping , Zhuang Jihua , Wang Bo , Liu Baohong , Kang Yijin , Tang Yi
Published: October 2005

An enzyme‐immobilized nanozeolite‐assembled electrode was prepared by controlled assembly of nanometer‐sized Linder type‐L zeolite (nano‐LTL‐zeolite) on an indium tin oxide (ITO) glass electrode surface, and subsequent immobilization of cytochrome c. Cyclic voltammetric (CV) and amperometric experiments showed that, relative to other reported electrodes, the enzyme‐immobilized electrodes possess fast electron‐transfer rates (2.2 s−1), a broad linear range (15–540 μmol L−1), a low detection limit (3.2 nmol L−1), a remarkably long lifetime (5 months), and high stability in the pH range 5–10. These characteristics could be due to the fact that nanozeolites assembled on ITO have high immobilization ability and facilitate interaction with enzymes. The function controllability of these enzyme electrodes, resulting from the facile manipulability of nanozeolite‐assembled layers, may provide a possibility to rationally design biosensors.
The Transfer of Tin and Germanium Atoms from N‐Heterocyclic Stannylenes and Germylenes to Diazadienes
Authors: Gans‐Eichler Timo , Gudat Dietrich , Nättinen Kalle , Nieger Martin
Published: October 2005

New N‐heterocyclic stannylenes and germylenes were synthesized by transamination of E{N(SiMe3)2} (E=Ge, Sn) with α‐amino‐aldimines or ethylidene‐1,2‐diamines and were characterized by spectroscopic methods and in the case of the germylene 10 g by X‐ray diffraction. The reactions of several germylenes and stannylenes with diazadienes were studied by using dynamic NMR and computational methods. Experimental and theoretical studies confirmed that metathesis with exchange of the Group 14 atom is feasible for both stannylenes and germylenes, with exchange rates being generally higher for stannylenes. The metathesis of the diazadiene 3 b and the stannylene 1 b follows second‐order kinetics and exhibits a sizeable negative entropy of activation. The transfer reaction is inhibited by bulky substituents in both reactants and surprisingly coincides with a suppression of the fragmentation of the stannylene into tin and diazadiene. A connection between oxidative addition and ring fragmentation was also observed in the reaction of 1 f with sulfur. Density functional theory (DFT) calculations suggest that all metathesis reactions proceed via transient spirocyclic [1+4] cycloaddition products, the formation of which is generally endothermic and endergonic. The spirostannanes display a distorted Ψ‐tbp geometry at the tin atom and their cycloreversion requires low or nearly negligible activation energies; spirogermanes exhibit distorted tetrahedral central atoms and sizeable energy barriers with respect to the same reaction. Complementary studies of cycloadditions of diazadienes to triplet germylenes or stannylenes indicate that these reactions are exothermic. The lowest triplet state in the carbene homologues results from promotion of an electron from an n(N) orbital with π character rather than the n(C)‐σ orbital as in carbenes, and singlet–triplet excitation energies decrease from carbon to tin. Spirostannanes exhibit a triplet ground‐state multiplicity that implies that the energy hypersurfaces for the reactions of singlet and triplet stannylenes with diazadienes intersect; for germylenes, the singlet hypersurface is always lower in energy. A reaction mechanism explaining the different thermal stabilities of N‐heterocyclic germylenes and stannylenes, and the coincidence between ring metathesis and thermal decomposition of the latter, is proposed based on the different separation of the singlet and triplet energy hypersurfaces.
Synthesis of Functionalized Vinylgermanes through a New Ruthenium‐Catalyzed Coupling Reaction
Authors: Marciniec Bogdan , Ławicka Hanna , Majchrzak Mariusz , Kubicki Maciej , Kownacki Ireneusz
Published: October 2005

Vinyl‐substituted germanes react stereo‐ and regioselectively with olefins in the presence of complexes containing RuH and RuGe bonds with the formation of functionalized vinylgermanes that cannot be synthesized by olefin cross‐metathesis procedures. The reaction opens a new catalytic route for preparation of a class of organogermanes that are potent organometallic reagents for organic synthesis because they show very low toxicity and could replace organotin compounds. The mechanism of this new catalytic route was proven to involve an interesting insertion of the vinylgermane into the RuH bond and β‐Ge transfer to the metal with elimination of ethylene and generation of an RuGe bond, followed by insertion of the alkene into the RuGe bond and β‐H transfer to the metal to eliminate the substituted vinylgermane.
Ruthenium Complexes with the Stanna‐closo‐dodecaborate Ligand: Coexistence of η1(Sn) and η3(BH) Coordination
Authors: Gädt Torben , Grau Beatrice , Eichele Klaus , Pantenburg Ingo , Wesemann Lars
Published: October 2005

Four stanna‐closo‐dodecaborate complexes of ruthenium have been prepared and characterized by multinuclear NMR studies in solution and in the solid state. The solid‐state structures of the dimeric zwitterions [{Ru(dppb)(SnB11H11)}2] (2) (dppb=bis(diphenylphosphino)butane), [{Ru(PPh3)2(SnB11H11)}2] (3), and the dianionic ruthenium complex [Bu3MeN]2[Ru(dppb){2,7,8‐(μ‐H)3‐exo‐SnB11H11}(SnB11H11)] (4) were determined by X‐ray crystal structure analysis; they establish an unprecedented structural motif in the chemistry of heteroboranes and transition‐metal fragments with the stanna‐closo‐dodecaborate moiety as a two‐faced ligand that exhibits η1(Sn) as well as η3(BH) coordination. The η3‐coordinated stannaborate in 4 and in the isostructural compound [Bu3MeN]2[Ru(PPh3)2{2,7,8‐(μ‐H)3‐exo‐SnB11H11}(SnB11H11)] (5) shows fluxional behavior, which was studied in detail by using 31P{1H} EXSY and DNMR experiments. The activation parameters for the dynamic process of 5 are given.
Cover Picture: The Chemistry of Wine Polyphenolic C‐Glycosidic Ellagitannins Targeting Human Topoisomerase II (Chem. Eur. J. 22/2005)
Authors: Quideau Stéphane , Jourdes Michael , Lefeuvre Dorothée , Montaudon Danièle , Saucier Cédric , Glories Yves , Pardon Patrick , Pourquier Philippe
Published: October 2005

The chemistry of oak‐derived NHTP‐bearing C‐glycosidic ellagitannins found in wine is reported by S. Quideau et al. in their Full Paper on page 6503 ff. These natural products are extracted by the wine solution during aging in barrels and have the capability to combine covalently by means of substitution reactions with a variety of grape‐derived nucleophilic species. The condensation products thus obtained can evidently contribute to the modulation of wine organoleptic properties, as well as possessing pharmacologically relevant activities.
Prozessintensivierung durch reaktive Carrier bei Reaktivextraktion und ‐sorption
Authors: Bart Hans‐Jörg
Published: October 2005

Reaktivextraktion und ‐sorption haben neben Applikationen in der Umwelttechnik und Hydrometallurgie ein großes Einsatzpotential bei der Aufreinigung pharmazeutischer Wirkstoffe oder zur Gewinnung chemischer Verbindungen aus Naturstoffen. Eine schwierige Aufgabenstellung ist dann die aufwändige Trennung von optischen Isomeren bzw. die von Positionsisomeren. Dazu wird die Problematik der Auswahl der reaktiven Selektoren diskutiert, wobei Gemeinsamkeiten der beiden Trenntechniken herausgearbeitet werden. Es gibt auch die Möglichkeit, die Selektoren in Mizellen zu immobilisieren oder auf Trägerharze zu imprägnieren, um so neue Anwendungsfelder zu erschließen. Ergänzend dazu werden die möglichen apparativen Umsetzungen besprochen.
Reaktive Chromatographie
Authors: Ströhlein G. , Assunção Y. , Morbidelli M. , Mazzotti M. , Proplesch R.
Published: October 2005

Reaktive Chromatographie integriert einen heterogen katalysierten Reaktionsschritt mit einer chromatographischen Trennung in einem Apparat, so dass gleichgewichtslimitierte Reaktionen zu vollständigem Umsatz gebracht werden können. Es werden typische Prozesse beschrieben, Methoden zur Bestimmung der Modellparameter erläutert und experimentelle Ergebnisse vorgestellt.
Wärmeabfuhr und Rückvermischung in mikrostrukturierten Apparaten
Authors: Knösche C. M.
Published: October 2005

In den letzten Jahren hat das Interesse von Forschung und industriellen Anwendern an der Mikroreaktionstechnik und an ihren Anwendungen stark zugenommen. Eine Vielzahl von Veröffentlichungen und mehrere internationale Konferenzen belegen diese Entwicklung eindrucksvoll. Die Gründe hierfür lassen sich auf eine Reihe vorteilhafter Eigenschaften von Mikroreaktorsystemen zurückführen. Zu diesen gehören u. a. die sehr kurzen Mischzeiten in Mikromischern, die sicherheitstechnischen Vorteile mikrostrukturierter Reaktoren, die sehr gute Isothermie in Mikroreaktoren und das Plug‐Flow‐Verhalten bzgl. der Konzentration in Mikrokanälen. Die beiden letztgenannten Punkte sind im Rahmen der Prozessintensivierung von grundlegender Bedeutung und sollen in dieser Arbeit näher beleuchtet werden.
Rigorose Modellierung und Simulation von Chemisorptionsprozessen
Authors: Hüpen B. , Kenig E. Y.
Published: October 2005

Unter Chemisorptionsprozessen, die zu den wichtigsten Verfahren in der chemischen Industrie gehören, versteht man die Ab‐ und Desorption von Gasen in bzw. aus Flüssigkeiten in Kombination mit simultan ablaufenden Reaktionen. In der Regel handelt es sich um sehr komplexe Prozesse, zu deren genauen Beschreibung eine detaillierte Modellierung notwendig ist. In diesem Beitrag wird ein allgemeingültiger, detaillierter Ansatz zur Darstellung verschiedenster Chemisorptionsprozesse und Kontaktapparate vorgestellt. Die Validierung erfolgt anhand von vier Prozessen, wobei es sich im Einzelnen um die Absorption von Schwefeldioxid in einem Venturiwäscher, die Absorption von Stickoxiden in Packungs‐ und Bodenkolonnen und um eine Kreislaufwäsche zur selektiven Entfernung von H2S handelt. Für alle Prozesse ergeben sich gute bis sehr gute Übereinstimmungen zwischen Simulation und Experiment, was die Allgemeingültigkeit, Genauigkeit und Prädiktivität des entwickelten Ansatzes belegt.
Reaktivkristallisation
Authors: Ulrich J. , Heinrich J.
Published: October 2005

Reaktivkristallisation ist ein gebräuchlicher Prozess in der chemischen Industrie. Er umfasst den Zusammenschluss der beiden Grundoperationen chemische Reaktion und physikalische Trennung mittels Kristallisation. Reaktivkristallisation ist somit ein Mehrphasenprozess, in dem physikalische Prozesse des Stoff‐ und Wärmeaustausches als auch multiple chemische Reaktionen simultan ablaufen. Das Hauptaugenmerk des Übersichtsartikels soll auf die Kinetik, den „Kern”︁ der Reaktivkristallisation, gelegt werden. Im ersten Teil werden allgemeine Interaktionen der verschiedenen Teilprozesse dargestellt und deren gezielte Steuerung zu einer gewünschten Produktqualität diskutiert. Im zweiten Teil wird ein Überblick über den Einfluss von Nicht‐Idealitäten auf die Produkteigenschaften gegeben. Abschließend werden die modellbasierte Versuchsplanung und Analyse sowie Modellierungsmethoden innerhalb der Reaktivkristallisation dargelegt.
Membranreaktoren
Authors: Westermann T. , Melin T.
Published: October 2005

Die Kombination von Reaktion und Membrantrennverfahren in einer Einheit verspricht in vielen Bereichen der chemischen und biochemischen Technik Verbesserungen gegenüber konventionellen Apparaten. Zahlreiche Forscher und Autoren haben sich mit unterschiedlichsten Fragestellungen und Zielsetzungen diesem Thema genähert. Dieser Beitrag soll einen umfassenden Überblick über die Möglichkeiten und Anwendungsgebiete sowie die Einschränkungen von Membranreaktoren geben. Unterteilt werden die Anwendungen nach der Hauptfunktion der Membran in Extraktor‐, Distributor‐ und Kontaktorprinzip. Den Anwendungen im biochemischen Bereich ist ein gesondertes Kapitel gewidmet.
Membranen in der Biotechnologie
Authors: Lütz S. , Wandrey C. , Rao N.
Published: October 2005

Membranen sind aus der Biotechnologie nicht mehr wegzudenken. Gerade in der Biokatalyse haben sie sich als Werkzeug zur Enzymrückhaltung bewährt und auch in industriellen Verfahren etabliert. Vorgestellt wird die Entwicklung von Membranreaktoren für biotechnologische Prozesse. Dabei werden Membransysteme zur Substratdosierung (z. B. Begasung), Katalysatorrückhaltung (z. B. Ultrafiltration), Produktentfernung (z. B. Pervaporation) und Entsalzung vorgestellt. Darüber hinaus wird die Nutzung von Membranen in der Bioelektrochemie behandelt.
Mikrovermischung in reaktiven deformierbaren Blasen‐ und Tropfenschwärmen
Authors: Khinast J. G.
Published: October 2005

Detaillierte numerische Simulationen reagierender deformierbarer Einzelblasen und Tropfen sowie reagierender Blasenschwärme wurden durchgeführt. Durch diese „first‐principle"‐Simulationen wurden Stoffaustauschkoeffizienten, Reaktionsausbeuten und Selektivitäten von verschiedenen chemischen Reaktionen bestimmt, die Ergebnisse für Blasen/Tröpfchenschwärme und Einzelblasen wurden verglichen. Die Vermischung in der Nachlaufströmung der Blasen ist ebenfalls beschrieben worden. Für vermischungssensible Reaktionsnetzwerke ließ sich zeigen, dass die Hydrodynamik des Blasenschwarms die Reaktionsselektivität entscheidend beeinflusst. Vier Fälle werden genauer diskutiert: stark exotherme Reaktionen, heterogen katalysierte Reaktionen, tierische Zellkulturen und experimentelle Daten. Mit den Ergebnissen ist es möglich, Blasenschwärme und die Auswirkung der Hydrodynamik des Schwarms auf reagierende Systeme im Detail zu untersuchen. Dies ist ein wichtiger Schritt in Richtung effektiver Prozessintensivierung, da das Verständnis des komplexen Verhaltens von Blasenschwärmen entscheidend für die Beschreibung des Stofftransportes und der chemische Reaktionen ist.
Reaktivdestillation
Authors: Kaibel G. , Holtmann T. , Miller C. , Schoenmakers H.
Published: October 2005

Die Reaktivdestillation bietet wegen der intensiven gegenseitigen Beeinflussung von chemischer Reaktion und destillativer Aufarbeitung besondere Chancen für innovative vorteilhafte Verfahrensführungen. Die für die chemische Reaktion wichtige Beeinflussung von Konzentrations‐ und Temperaturfeldern – wie das der Reaktion überlagerte Entfernen von Reaktionsprodukten zur Erhöhung des Gleichgewichtsumsatzes, das Abführen der Reaktionswärme über die Siedekühlung und ihre Nutzung zur Stofftrennung, die Gegenstromführung von Reaktanden, um nur einige Beispiele zu nennen – ermöglicht in vielen Fällen attraktive Verfahrensverbesserungen im Vergleich zu konventionellen Lösungen. Der Beitrag gibt einen Überblick über Verfahrensvarianten, Anwendungen und technische Ausgestaltungen von Reaktivdestillationen sowie einen Ausblick auf zukünftige Trends.
Prozessintensivierung heterogen katalysierter Gas/Flüssig‐Reaktionen mit Monolithreaktoren
Authors: Bauer T. , Schubert M. , Lange R.
Published: October 2005

Aufgrund der wirtschaftlichen und ökologischen Anforderungen ist die Optimierung bestehender chemischer Prozesse eine zentrale Herausforderung unserer Zeit. Durch die Entwicklung neuartiger Apparate und Verfahren in der chemischen Industrie, die zu drastischen Verbesserungen der chemischen Prozesse und zur Energieeinsparung führen, kann diese Schlüsselaufgabe erfolgreich gelöst werden. Im Bereich der Mehrphasenreaktionstechnik ist die Anwendung von strukturierten Monolithreaktoren anstelle herkömmlicher Reaktoren, wie den Suspensions‐ und regellos gepackten Festbettreaktoren, eine viel versprechende Alternative. Dieser Beitrag diskutiert den aktuellen Stand von Forschung und industrieller Praxis zum Einsatz von Monolithreaktoren für heterogen katalysierte Gas/Flüssig‐Reaktionen.
Prozessintensivierung – Eine strategische Option für die chemische Industrie
Authors: Hüther A. , Geißelmann A. , Hahn H.
Published: October 2005

Konzepte und Methoden der Prozessintensivierung werden seit einigen Jahren an Hochschulen und zunehmend auch in der chemischen Industrie entwickelt und eingesetzt. Dabei stehen technologische Ansätze zur signifikanten Verbesserung von Produktionsprozessen im Vordergrund. Mittels prozessintensivierender Technologien sollen Limitierungen im Energie‐ und Stofftransport minimiert sowie die Reaktionskinetik maximal ausgenutzt werden. Die Degussa AG als führender Anbieter in der Spezialchemie sieht Prozessintensivierung als einen ganzheitlichen Managementprozess, um den wachsenden Herausforderungen des globalen Wettbewerbs zu begegnen. Neben technologischen Aspekten spielen dabei vor allem wirtschaftliche Betrachtungen eine entscheidende Rolle. Aufgrund des Potenzials, das der Prozessintensivierung beigemessen wird, hat die Degussa AG ihr neues Projekthaus „Process Intensification”︁ unter Regie von Creavis Technologies & Innovation gestartet. In diesem Artikel wird der so verfolgte ganzheitliche Ansatz der Prozessintensivierung vorgestellt und anhand zweier konkreter Fälle erläutert.
Prozessanalyse hybrider Trennverfahren am Beispiel der Kopplung von Rektifikation und Membrantrennung
Authors: Kreis P. , Górak A.
Published: October 2005

Um der Forderung nach immer wirtschaftlicheren und umweltschonenderen Produktionsverfahren in der chemischen Industrie nachzukommen, sind hybride Trennverfahren derzeit verstärkt im Fokus wissenschaftlicher und industrieller Forschung. Insbesondere die Kombination von thermischer Trenntechnik und innovativen Verfahren schafft starke Synergien. Deren Potenzial wird im industriellen Maßstab zurzeit kaum ausgeschöpft, da eine sichere Prozessanalyse aufgrund der Komplexität nur in begrenztem Umfang möglich ist. Während bisher für Auslegung und Optimierung ausschließlich Short‐Cut‐ und Gleichgewichtsmodelle eingesetzt werden, wird in diesem Beitrag für die Prozessanalyse ausschließlich auf Stoffaustauschmodelle zurückgegriffen. Die Anwendbarkeit wird anhand der Trennung eines ternären Gemisches mittels Rektifikation/Pervaporation gezeigt. Der Einfluss relevanter Struktur‐ und Betriebsparameter auf die erforderliche Membranfläche und Kosten wird untersucht. Abschließend zeigt ein Verfahrensvergleich die Stärken und Schwächen des Hybridprozesses auf.
Kontinuierliche Herstellung von kosmetischen Fettsäureestern mittels Reaktivdestillation und Pervaporation
Authors: von Scala C. , Fässler P. , Gerla J. , Maus E.
Published: October 2005

Es konnte ein Verfahren realisiert und zum Patent angemeldet werden, das das Potenzial hat, den herkömmlichen diskontinuierlichen Produktionsprozess von Fettsäureestern in vielen Fällen abzulösen. Das Zusammenfassen der chemischen Reaktion und der destillativen Stofftrennung in einer Reaktivdestillationskolonne erlaubt eine kontinuierliche Betriebsweise. Diese führt zu konstant hoher Produktqualität und ist gleichzeitig einfacher in der Handhabung und der Prozesssteuerung, was sich besonders bei größeren Produktionskapazitäten auszahlt. Die Pervaporationsmembrananlage zur Aufbereitung des Destillatstroms ersetzt zwei Destillationskolonnen und reduziert damit zusätzlich die Investitions‐ und Betriebskosten der Anlage. Weiterhin wird die benötigte Installationsfläche der Anlage wesentlich verringert.
Numerical simulation on joint motion process of various modes of caisson breakwater under wave excitation
Authors: Yuan‐Zhan Wang , Nan‐Nan Chen , Li‐Hua Chi
Published: October 2005

A caisson breakwater may experience various modes of motions under wave action. The elementary motion modes are classified into two categories, i.e. the horizontal and rotational vibration coupled motion and the horizontal slide and rotational vibration coupled motion. The motion modes of caisson will transform from one to another depending on the wave forces and the motion behaviours of a caisson. The numerical models of the two motion modes of caisson are developed, the numerical simulation procedure for joint motion process of the two modes of caisson breakwater under wave excitation is presented and tested by a physical model experiment. It is concluded that the simulation procedure is reliable and can be applied to the dynamic stability analysis of caisson breakwaters. Copyright © 2005 John Wiley & Sons, Ltd.
An effective composite laminated curved beam element
Authors: Kim Jin‐Gon
Published: October 2005

In this study, we present a new highly accurate composite laminated hybrid‐mixed curved beam element. The present element, which is based on the Hellinger–Reissner variational principle and the first‐order shear deformation lamination theory, employs consistent stress parameters corresponding to cubic displacement polynomials with additional nodeless degrees of freedom in order to resolve the numerical difficulties due to the spurious constraints. The stress parameters are eliminated and the nodeless degrees are condensed out to obtain the (6 × 6) element stiffness matrix. Several numerical examples confirm the superior behaviour of the present hybrid‐mixed laminated curved beam element. Copyright © 2005 John Wiley & Sons, Ltd.
Algorithms for automatic generating interior nodal points and Delaunay triangulation using advancing front technique
Authors: Li S. S. , Shi John Z.
Published: October 2005

A new algorithm is proposed for generating interior nodal points within an arbitrary two‐dimensional domain. The algorithm is based on a background triangle mesh and the contours on the background mesh. The newly generated points are exactly within the domain with smooth point densities and a good quality of the final mesh. An improved Delaunay triangulation algorithm using advancing front technique is also proposed. The present algorithm is more general and robust. A FORTRAN 90 program based on the present algorithms is developed and has been successfully applied in many projects. Examples are given to show the effectiveness and robustness of the algorithms. Copyright © 2005 John Wiley & Sons, Ltd.
Interactions between sleeping position and feeding on cardiorespiratory activity in preterm infants
Authors: Fifer William P. , Myers Michael M. , Sahni Rakesh , Ohira‐Kist Kiyoko , Kashyap Sudha , Stark Raymond I. , Schulze Karl F.
Published: October 2005

Infants sleeping in the prone position are at greater risk for sudden infant death syndrome (SIDS). Sleep position‐dependent changes in cardiorespiratory activity may contribute to this increased risk. Cardiorespiratory activity is also affected by feeding. Twenty prematurely‐born infants were studied at 31–36 weeks postconceptional age while sleeping in the prone and supine positions. Heart rate, respiratory rate, and patterns of variability were recorded during interfeed intervals, and effects of position and time after feeding were analyzed by repeated measures analyses of variance. There were significant effects of both sleeping position and time after feeding. Heart rate is higher and heart period variability is lower in the prone position, and the effects of sleeping position on cardiac functioning are more pronounced during the middle of the intrafeed interval. In preterm infants, autonomic responses to nutrient processing modulate the cardiorespiratory effects of sleeping position. Prone sleeping risk may vary with time after feeding. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 288–296, 2005.
Evolution and developmental patterning of the vertebrate skeletal muscles: Perspectives from the lamprey
Authors: Kusakabe Rie , Kuratani Shigeru
Published: October 2005

The myotome in gnathostome vertebrates, which gives rise to the trunk skeletal muscles, consists of epaxial (dorsal) and hypaxial (ventral) portions, separated by the horizontal myoseptum. The hypaxial portion contains some highly derived musculature that is functionally as well as morphologically well differentiated in all the gnathostome species. In contrast, the trunk muscles of agnathan lampreys lack these distinctions and any semblance of limb muscles. Therefore, the lamprey myotomes probably represent a primitive condition compared with gnathostomes. In this review, we compare the patterns of expression of some muscle‐specific genes between the lamprey and gnathostomes. Although the cellular and tissue morphology of lamprey myotomes seems uniform and undifferentiated, some of the muscle‐specific genes are expressed in a spatially restricted manner. The lampreyPax3/7gene, a cognate of gnathostomePax3, is expressed only at the lateral edge of the myotomes and in the hypobranchial muscle, which we presume is homologous to the gnathostome hypobranchial muscle. Thus, the emergence of some part of a hypaxial‐specific gene regulatory cascade might have evolved before the agnathan/gnathostome divergence, or before the evolutionary separation of epaxial and hypaxial muscles. Developmental Dynamics 234:824–834, 2005. © 2005 Wiley‐Liss, Inc.
Bidirectional fusion of the heart‐forming fields in the developing chick embryo
Authors: Moreno‐Rodriguez R.A. , Krug E.L. , Reyes L. , Villavicencio L. , Mjaatvedt C.H. , Markwald R.R.
Published: October 2005

It is generally thought that the early pre‐tubular chick heart is formed by fusion of the anterior or cephalic limits of the paired cardiogenic fields. However, this study shows that the heart fields initially fuse at their midpoint to form a transitory “butterfly”‐shaped, cardiogenic structure. Fusion then progresses bi‐directionally along the longitudinal axis in both cranial and caudal directions. Using in vivo labeling, we demonstrate that cells along the ventral fusion line are highly motile, crossing future primitive segments. We found that mesoderm cells migrated cephalically from the unfused tips of the anterior/cephalic wings into the head mesenchyme in the region that has been called the secondary heart field. Perturbing the anterior/cranial fusion results in formation of a bi‐conal heart. A theoretical role of the ventral fusion line acting as a “heart organizer” and its role in cardia bifida is discussed. Developmental Dynamics 235:191–202, 2006. © 2005 Wiley‐Liss, Inc.
Zebrafish id2 developmental expression pattern contains evolutionary conserved and species‐specific characteristics
Authors: Chong Shang‐Wei , Nguyen Thi‐Thu‐Hang , Chu Lee‐Thean , Jiang Yun‐Jin , Korzh Vladimir
Published: October 2005

The inhibitor of differentiation or inhibitor of DNA binding (Id) family are members of the helix–loop–helix (HLH) group of transcription factors that play important roles in cell proliferation, differentiation, cell cycle control, and apoptosis. They modulate the formation of active class A–class B basic HLH (bHLH) complexes. Ids lack the amino‐terminal associated basic region necessary for DNA binding, thus sequestering the class A factors, inhibiting the formation of active class A–class B heterodimers and, therefore, are considered to act as dominant‐negative regulators of differentiation pathways. We isolated zebrafish id2, and its expression during development was characterized. id2, in addition to regions of expression detected in Xenopus and mice, is also expressed in the tegmentum; midbrain–hindbrain boundary; cerebellum; rhombomeres 2,3,4,6; notochord; and corpuscles of Stannius. Furthermore, we show that expression of id2 is repressed in mind bomb mutants, suggesting a role of Notch upstream of Id2. Developmental Dynamics 234:1055–1063, 2005. © 2005 Wiley‐Liss, Inc.
Bulimia nervosa in an elderly male: A case report
Authors: Morgan C. Don , Marsh Connie
Published: October 2005

Objective

There is increasing knowledge regarding demographics, comorbid psychiatric disorders, and symptoms characteristic of males suffering from eating disorders.

Method

The current case report describes the history, symptom progression, and successful treatment of an elderly bulimic male whose presentation was atypical.

Results

This case underscores the need to consider the presence of an eating disorder regardless of age and gender, when a patient complains of unexplained nausea, abdominal pain, or vomiting. © 2005 by Wiley Periodicals, Inc.
Dehydroepiandrosterone replacement in patients with Addison's disease has a bimodal effect on regulatory (CD4+CD25hi and CD4+FoxP3+) T cells
Authors: Coles Alasdair J. , Thompson Sara , Cox Amanda L. , Curran Suzanne , Gurnell Elli M. , Chatterjee V. Krishna
Published: October 2005

Oral replacement of the near‐total deficiency of dehydroepiandrosterone (DHEA) in patients with Addison's disease (adrenal insufficiency) enhances mood and well‐being and reduces fatigue. We studied the immunological effects of 12 wk of oral DHEA treatment in ten patients with Addison's disease receiving their normal mineralo‐ and glucocorticoid hormone replacement. We found that baseline circulating regulatory T cells were reduced in Addison's disease patients compared to controls, a hitherto unrecognised defect in this disorder. Oral DHEA treatment had a bimodal effect on naturally occurring regulatory (CD4+CD25hiFoxP3+) T cells and lymphocyte FoxP3 expression. Oral DHEA replacement restored normal levels of regulatory T cells and led to increased FoxP3 expression. These effects were probably responsible for a suppression of constitutive cytokine expression following DHEA withdrawal. In contrast, oral DHEA treatment led to reduced FoxP3 expression induced by TCR engagement and so augmented the cytokine response, but without a bias towards the Th1 or Th2 phenotype. NK and NKT cell numbers fell during DHEA treatment, and homeostatic lymphocyte proliferation was increased. We conclude that DHEA replacement in Addison's disease has significant immunomodulatory properties and propose that it has a greater impact on the human immune system than would be expected from its classification as a dietary supplement.
Thermo‐Mechanical Model of Solid Oxide Fuel Cell Fed with Methane
Authors: Laurencin J. , Morel B. , Bultel Y. , Lefebvre‐Joud F.
Published: October 2005

Internal steam reforming induces an inhomogeneous temperature distribution in SOFC cell. A thermo‐mechanical model has been developed to determine both the temperature gradient and the stress field within an anode supported cell structure fed with methane. Residual stresses due to manufacturing process and thermal stresses induced by the mismatch in thermal expansion coefficients have been taken into account. Mechanical external loading of the cell has been neglected.

The results of this study have shown a cooling area at the inlet of the cell due to the endothermic steam reforming reaction. However, in our conditions of simulation, the temperature gradient in the cell has been found relatively low (0.2 °C mm–1). Consequently, thermal stresses in the three layers of the cell are mainly due to the heating from room temperature to the operating one.

Mechanical calculations have been performed considering a low compressive residual stress in the thin electrolyte at room temperature. In these conditions, a high tensile stress has been calculated in the thin electrolyte at operating temperature. Its value is nearly homogenous all over the layer and exceeds the limit strength of the Yttria Stabilised Zirconia. The brittle fracture of electrolyte layer in one thermal cycle has been analysed by a Weibull distribution. The failure probability reaches 66% for a 60 micrometer electrolyte thickness. However, this result depends strongly on the layer thickness. Moreover, a singular stress field analysis has allowed determining an important tensile stress at the anode edge (on the circumferential free surface). It has been shown that fracture can be initiated at defects in this tensile surface, if the fracture toughness of the anodic cermet is inferior to 0.41 MPa √m.
t(3;14)(p14;q32) Results in aberrant expression of FOXP1 in a case of diffuse large B‐cell lymphoma
Authors: Fenton James A. L. , Schuuring Ed , Barrans Sharon L. , Banham Alison H. , Rollinson Sara J. , Morgan Gareth J. , Jack Andrew S. , van Krieken J. Han. J. M. , Kluin Philip M
Published: October 2005

Strong expression of Forkhead box‐P1 (FOXP1), a winged‐helix transcription factor, has been identified as an independent prognostic factor in diffuse large B‐cell lymphoma (DLBCL). However, possible mechanisms of deregulation of this gene, on 3p14.1, have yet to be elucidated. We have identified a breakpoint at the IGA1 gene in the immunoglobulin heavy chain (IGH) locus at 14q32 that was juxtaposed to the FOXP1 gene locus in a gastric DLBCL that showed strong expression of FOXP1. This may be one possible mechanism of deregulating FOXP1 expression by placing it under the control of IGH enhancers. © 2005 Wiley‐Liss, Inc.
Androgen inducibility of Fgf8 in Shionogi carcinoma 115 cells correlates with an adjacent t(5;19) translocation
Authors: Erdreich‐Epstein Anat , Ganguly Amit K. , Shi Xiang‐He , Zimonjic Drazen B. , Shackleford Gregory M.
Published: October 2005

Fgf8 (fibroblast growth factor 8) was initially cloned from a mouse mammary tumor cell line derived from the androgen‐dependent Shionogi carcinoma 115. The androgen‐inducible expression of Fgf8 in this tumor controls its androgen‐dependent phenotype, thus stimulating interest in this gene as a possible factor in human prostate cancer and other androgen‐sensitive cancers. However, apart from Shionogi carcinoma 115, the androgen inducibility of Fgf8 is controversial. In the present study, having not detected androgen‐inducible expression of Fgf8 in other mouse mammary cell lines or mouse prostate, we examined the Shionogi carcinoma 115‐derived S115 cell line for mouse mammary tumor virus (MMTV) insertions or other nearby DNA rearrangements that might explain the androgen inducibility of Fgf8 in these cells. Southern blotting did not detect MMTV insertions near Fgf8 but did reveal a specific DNA rearrangement 3.7 kb upstream of Fgf8 in S115 cells and in other cells (SC115) independently derived from Shionogi carcinoma 115. Spectral karyotyping of S115 cells and sequencing of the cloned rearrangement junctions indicate that Fgf8 is involved in a t(5;19) translocation. The chromosome 5 sequence joined to Fgf8 is immediately adjacent to Smr2 (submaxillary gland androgen‐regulated protein 2) and includes Muc10 (mucin 10), two genes that we show are testosterone inducible in S115 cells, suggesting that the androgen‐dependent expression of Fgf8 in Shionogi carcinoma 115 and derivative cells results from this translocation. Together, these results suggest that androgen inducibility is not an inherent property of the Fgf8 gene, which has implications regarding this gene's proposed role in the etiology of hormone‐responsive cancers. Published 2005 Wiley‐Liss, Inc.
Interferon Alfa-2b in Combination With Ribavirin for the Treatment of Chronic Hepatitis C in Children: Efficacy, Safety, and Pharmacokinetics *
Authors: González-Peralta Regino P. , Kelly Deirdre A. , Haber Barbara , Molleston Jean , Murray Karen F. , Jonas Maureen M. , Shelton Mark , Mieli-Vergani Giorgina , Lurie Yoav , Martin Steven , Lang Thomas , Baczkowski Andrew , Geffner Michael , Gupta Samir , Laughlin Mark
Published: October 2005

Abstract

Chronic hepatitis C virus (HCV) infection is usually asymptomatic in children, but significant liver disease may occur. We evaluated the efficacy, safety, and pharmacokinetics of interferon alfa-2b and ribavirin in children with chronic HCV. We determined the optimal ribavirin dose in an initial cohort of a phase 1 study and then subsequently used it, in combination with interferon alfa-2b, in a second cohort of this study and a phase 3 trial. The primary efficacy endpoint in all studies was sustained virological response, defined by undetectable serum HCV RNA 24 weeks after completion of therapy. All efficacy and safety analyses were performed on the intent-to-treat population. Children receiving interferon alfa-2b plus ribavirin 15 mg/kg/d in the phase 1 study had the maximum reduction in serum HCV RNA at treatment weeks 4 and 12 with an acceptable safety profile. This ribavirin dose was selected as optimal and used in all subsequent studies. In all, 46% (54/118) of optimally treated children achieved sustained virological response. Sustained virological response was significantly higher in children with HCV genotype 2/3 (84%) than in those with HCV genotype 1 (36%). Adverse events led to dose modification in 37 (31%) and discontinuation in 8 (7%). Multiple-dose interferon alfa-2b and ribavirin peak and trough concentrations and area-under-the-curve were similar between children and adults.
In conclusion
, interferon alfa-2b in combination with ribavirin is effective and safe in children with chronic hepatitis C virus. (Hepatology 2005;42:1010–1018.)
Early Intrahepatic Antigen-Specific Retention of Naïve CD8+ T Cells is Predominantly ICAM-1/LFA-1 Dependent in Mice *
Authors: Bertolino Patrick , Schrage Arnhild , Bowen David G. , Klugewitz Katja , Ghani Saeed , Eulenburg Katharina , Holz Lauren , Hogg Nancy , McCaughan Geoffrey W. , Hamann Alf
Published: October 2005

Abstract

We have previously shown that naïve CD8+ T cells recognizing their cognate antigen within the liver are retained and undergo activation

in situ

, independent from lymphoid tissues. Intrahepatic primary T cell activation results in apoptosis and may play a crucial role in the ability of the liver to induce tolerance. Although adhesion molecules required for intrahepatic retention of T cells that have undergone previous extra-hepatic activation have been characterized, adhesive interactions involved in selective antigen-dependent intrahepatic retention of naïve CD8+ T cells have not been investigated. By adoptively transferring radiolabeled T cell receptor (TCR)-transgenic CD8+ T cells into recipient animals ubiquitously expressing the relevant antigen, we show that 40% to 60 % of donor antigen–specific naïve CD8+ T cells were retained in the liver within 1 hour after transfer, despite ubiquitous expression of the antigen. Intravital microscopy showed that most donor naïve T cells slowed down and were irreversibly retained intrahepatically within the first few minutes after adoptive transfer, strongly suggesting that they were directly activated by liver cells

in situ

. This process was largely dependent on LFA-1 and ICAM-1, but was independent of blocking with antibodies against VCAM-1, α4 integrin, P-selectin, VAP-1, and β1 integrin. ICAM-2 seemed to play only a minor role in this process. Interestingly, LFA-1 expressed by both donor T cells and liver cells was involved in retention of the antigen-reactive T cells.
In conclusion
, LFA-1–dependent intrahepatic T cell retention and activation are linked events that may play a crucial role in the establishment of liver-induced antigen-specific tolerance.

Supplementary material for this article can be found on the H

epatology

website

(
http://www.interscience.wiley.com/jpages/0270-9139/suppmat/index.html
). (Hepatology 2005;42:1063–1071.)