bluuebunny/crossref_metadata_2025 huggingface dataset:
Mesoscopic systems with fixed number of electrons
Authors: Lehle W. , Schmid A.
Published: May 2007

In this paper, we study the physics of mesoscopic systems with noninteracting electrons of fixed number. From a technical point of view, this means a discussion of the differences between the canonical and the grand canonical ensemble (fixed versus fluctuating number of particles). Such a discussion is not trivial since the grand canonical ensemble is the most convenient basis for the statistics of identical particles and one has to spend labour in order to retrieve the canonical ensemble. Specifically, we are considering ensembles of mesoscopic systems with disorder, either by atomic defects or by fluctuations in their geometric definitions and we discuss various forms of disorder averages.
Transport in a fluctuating potential
Authors: Mielke Andreas
Published: May 2007

We study the overdamped motion of a particle in a fluctuating one‐dimensional periodic potential. The potential has no inversion symmetry, and the fluctuations are correlated in time. At finite temperatures, a stationary current is induced. The amplitude and the direction of the current depend on the details of the noise process that is responsible for the potential fluctuations. We discuss several limiting situations for a general case. Furthermore we calculate the current in the case of a piecewise linear potential for different noise processes and parameters. A detailed discussion of the results is given, including a discussion of the mechanism that is responsible for the current reversal. We compare the present results with results for transport in a ratchet‐like potential due to a fluctuating force. We also discuss the biological relevance of the present models for molecular motors. We present a model for the motion of molecular motors that explains why similar molecular motors can move in different directions.
Regioselective Borylation of Porphyrins by CH Bond Activation under Iridium Catalysis to Afford Useful Building Blocks for Porphyrin Assemblies
Authors: Hata Hiroshi , Yamaguchi Shigeru , Mori Goro , Nakazono Satomi , Katoh Taisuke , Takatsu Keishi , Hiroto Satoru , Shinokubo Hiroshi , Osuka Atsuhiro
Published: May 2007

Highly regioselective and efficient borylation of a variety of porphyrins has been achieved by reaction with bis(pinacolato)diboron through CH bond activation under iridium catalysis on the basis of the synthetic protocol developed by Miyaura, Hartwig, and Smith. A boryl group can be selectively introduced at sterically uncongested positions in the peripheral aryl groups of porphyrin substrates whose peripheral β‐positions are sterically hindered. Curiously, β substituents adjacent to the aryl group to be borylated have unexpectedly large effects on the regioselectivity, because the iridium catalyst can discriminate between subtle steric differences. Chemoselective borylation was also achieved for several functionalized porphyrins. This borylation protocol can be applied to various monomeric and oligomeric functional porphyrins, hence offering an efficient route to elaborate multiporphyrin‐based molecular constructs.
A semi‐Markov model of disease recurrence in insured dogs
Authors: Wang Xikui , Pai Jeffrey S. , Shand Kevin J.
Published: May 2007

We use a semi‐Markov model to analyse the stochastic dynamics of disease occurrence of dogs insured in Canada from 1990 to 1999, and the probability pattern of death from illness. After statistically justifying the use of a stochastic model, we demonstrate that a stationary first‐order semi‐Markov process is appropriate for analysing the available data set. The probability transition function is estimated and its stationarity is tested statistically. Homogeneity of the semi‐Markov model with respect to important covariates (such as geographic location, insurance plan, breed and age) is also statistically examined. We conclude with discussions and implications of our results in veterinary contents. Copyright © 2007 John Wiley & Sons, Ltd.
Eine neue Darstellungsweise für 1.3‐Diketone aus Vinylacetat und Säurechloriden
Authors: Sieglitz Adolf , Horn Otto
Published: May 2007

Es wird die Umsetzung von Säurechloriden mit Vinylacetat in Gegenwart von Aluminiumchlorid zu symmetrischen 1.3‐Diketonen beschrieben. Als Nebenprodukte entstehen Acylacetone. Die Anwendbarkeit der Reaktion auf verschiedene Säurechloride wurde untersucht.
Darstellung und Wirkungen von Acetyl‐Derivaten des Cysteamins
Authors: Kuhn Richard , Quadbeck Günter
Published: May 2007

Äthylenimin reagiert mit Thioessigsäure unter Bildung von N‐Acetyl‐cysteamin, das durch Keten in N.S‐Diacetyl‐cysteamin und durch Essigsäureanhydrid in N.N.S‐Triacetyl‐cysteamin verwandelt werden kann. Die di‐und Triacetyl‐Verbindung bewirken eine langanhaltende Blutdrucksenkung.
Reaktionen mit Lithiumaluminiumhydrid: Reduktion von Heterocyclen mit Lithiumaluminiumhydrid
Authors: Bohlmann Ferdinand
Published: May 2007

Bei der Einwirkung von Lithiumaluminiumhydrid auf heterocyclische Verbindungen entstehen im allgemeinen die sonst oft nur schwer zugänglichen, sehr empfindlichen Dihydroverbindungen.
Notiz über einige Komplexbildner der Azomethin‐Reihe
Authors: Seyhan Mavaffak
Published: May 2007

Es werden die Darstellung zweier Azomethine und deren Uran‐Komplexe beschrieben.
Die Spaltung des α‐Oxy‐tryptophans in die optischen Antipoden
Authors: Kotake Munio , Sakan Takeo , Miwa Toshio
Published: May 2007

(+)‐α‐Oxy‐tryptophan, das von H. Wieland und B. Witkop als Bestandteil des Phalloidins in Amanita phalloides aufgefunden worden ist, wurde durch Spaltung der d,l‐Verbindung über das Brucin‐Salz der N‐Acetyl‐Verbindung ebenso wie die (−)‐Verbindung erhalten.
Über Abkömmlinge des Pantothenals
Authors: Bergel Franz , Hindley Nathan C. , Morrison Alexander L. , Moss A. Ronald
Published: May 2007

Die Diäthylacetale des d,l‐ und d(+)‐Pantothenals wurden hergestellt und einer milden Verseifung und Oxydation unterworfen, wobei in gewissem Maße Salze der entsprechenden Pantothensäuren gebildet wurden. Aus dem d,l‐Pantothenal ‐ diäthylacetal entstand durch Säurebehandlung eine hochschmelzende Verbindung, für die die vorläufige Formel eines „Dipantothenals”︁ (II) vorgeschlagen wird. Im Ratten‐Wachstumsversuch Zeigt diese Substanz eine deutliche Vitaminwirkung.
Über eine neue Synthese des β‐Oxindolyl‐(3)‐alanins (α‐Oxy‐tryptophans); ein Beitrag zum Anwendungsbereich der Sörenschen Aminosäure‐Synthese
Authors: Behringer Hans , Weissauer Hermann
Published: May 2007

Es wird bewiesen, daß bei der Kondensation von Malonester mit Thiokresylmethylen‐oxindol (II; R′=H, X=S·C 6H4·CH3) diese in 2‐Stellung des Oxindolrings erfolgt, was auch für die Umsetzung einiger anderer aktiver Methylenverbindungen mit Abkömmlingen des Oxymethylen‐oxindols wahrscheinlich ist. Chlormethylen‐oxindol (II; R′=H, X=Cl) läßt sich dagegen mit Natrium‐formamino‐malonester in den α‐Carbäthoxy‐α‐formamino‐β‐[isatyliden‐(3)]‐ propionsäureester (IV; R′=H, R″=NH·CHO) überführen, der durch Reduktion und Totalhydrolyse β‐Oxindolyl‐(3)‐alanin (I) liefert.

Es wird auf die Möglichkeit hingewiesen, aus dem erwähnten Zwischenprodukt IV das Dioxindolyl‐alanin (XII) zu synthetisieren, das als Vorstufe des N′ ‐Formyl‐kynurenins beim biologischen Abbau des Tryptophans in Betracht kommt.
Notiz über eine Reaktion des Pyridin‐aldehyds‐(4)
Authors: Mathes Wilhelm , Sauermilch Walter
Published: May 2007

Bei dem Versuch zur Darstellung des γ‐Pyridoins wird ein Reaktionsverlauf festgestellt, der unmittelbar zum hydrierten Pyridoin, dem Bis‐[γ‐pyridyl]‐glykol führt, das in 2 isomeren Formen erhalten wird.
Konstitution und Lichtabsorption, VI. Mitteil.: Zur Deutung von Polyacetylen‐Spektren, sowie Darstellung von Bis‐tert.‐butyl‐decapentain‐(1.3.5.7.9)
Authors: Bohlmann Ferdinand
Published: May 2007

Durch Darstellung des bisher noch fehlenden Gliedes, einer Pentaacetylen‐Verbindung, wurde die Reihe der Polyine vervollständigt. Die Unterschiede in den Spektren der Polyine gegenüber denen der Polyene werden gedeutet. Die verschiedene Lage der Maxima kommt durch die unterschiedlichen Bindungsabstände und die sich daraus ergebenden Unterschiede in der Länge der π‐Elektronenwolken zustande. Die größere Intensität der Banden bei den Polyinen ergibt sich aus der erhöhten Übergangswahrscheinlichkeit.
Reaktionen an der Carbonamid‐Gruppe
Authors: Heyns Kurt , Woyrsch Oscar‐Felix
Published: May 2007

Es werden die Umsetzungen von ϵ‐Caprolactam, 2.5‐Diketo‐piperazin, N‐Methyl‐acetamid und Glycylglycin mit Salpetriger Säure und Reaktionen der erhaltenen Nitroso‐Verbindungen untersucht. Gegenüber Diazomethan verhielt sich die ‐CO·NH‐Gruppe bisher widerstandsfähig.
Synthesen von α‐Aminosäuren, III. Mitteil.: threo‐p‐Nitro‐phenylserin
Authors: Ehrhart Gustav
Published: May 2007

Es wird die Kondensation von p‐Nitro‐benzaldehyd mit Glykokoll zu p‐Nitro‐phenylserin beschrieben und seine threo‐Konfiguration auf verschiedenen Wegen bewiesen.
Eine Synthese der Phenol‐β‐d‐glucuronsäure
Authors: Heyns Kurt , Kelch Claus
Published: May 2007

Es wird eine Synthese von Phenol‐β‐d‐glucuronid, ausgehend von d‐Glucuron, über den 1‐Brom‐triacetyl‐α‐d‐glucuronsäure‐methylester, beschrieben.
Über die Bildung von 1.3.4.5‐Tetraacetyl‐β‐d‐fructopyranose aus Keto‐ditrityl‐triacetyl‐fructose mittels Acetylbromids bzw. Perchlorsäure in Essigsäureanhydrid (Untersuchungen über Fructose‐acetate, II. Mitteilung
Authors: Hennig Ingeborg
Published: May 2007

Bei der Umsetzung von Keto‐ditrityl‐triacetyl‐fructose mit Acetylbromid in Essigsäureanhydrid oder Chloroform entsteht in der Kälte 1.3.4.5‐Tetraacetyl‐β‐d‐fructopyranose über Acetobromfructose als Zwischenstufe. In der Wärme findet einfacher Austausch von Trityl gegen Acetyl‐Gruppen zu Keto‐pentaacetyl‐fructose statt. Entsprechend Acetylbromid reagieren Essigsäureanhydrid + Perchlorsäure.
Über α‐ und β‐Sulfonyl‐sulfonium‐Salze
Authors: Böhme Horst , Heller Paul
Published: May 2007

α‐Sulfonyl‐sulfonium‐Salze lassen sich durch Oxydation von Alkylmercaptomethyl‐sulfonium‐Salzen mit Peressigsäure gewinnen; sie sind als Reineckate oder Methansulfonate beständig, zerfallen als Chloride hingegen in wäßriger Lösung unter Bildung von α‐Mercaptosulfonen.

β‐Sulfonyl‐sulfonium‐Salze entstehen durch Anlagerung von Alkylhalogeniden an β‐Sulfonyl‐sulfide; sie sind in wäßriger Lösung beständig und zerfallen bei Gegenwart von Alkali wie die analogen γ‐Keto‐sulfonium‐Salze in Dialkyl‐sulfide und Alkyl‐ bzw. Aryl‐vinyl‐sulfone.
Über das Dimere des α‐Phenyl‐butadiens. Zur Kenntnis der Dien‐Synthese mit unsymmetrischen Addenden
Authors: Alder Kurt , Haydn Joseph , Vogt Wilhelm
Published: May 2007

Die Konstitution und Konfiguration eines trans‐1‐Phenyl‐2‐styryl‐Δ5‐cyclohexens für das Dimerisationsprodukt aus α‐Phenyl‐butadien wurde bewiesen. Die Dimerisation stellt eine “partielle 1.4‐Addition” vor. Die ortho‐Stellung der Substituenten Phenyl und Styryl im Dimeren folgt den allgemeinen Regeln, die für Dien‐Synthesen mit unsymmetrischen Addenden gelten.
Über 1.2.4‐Thiodiazole, II. Mitteil.): N‐Methyl‐Derivate der Amino‐thiodiazole und Imino‐thiodiazoline
Authors: Goerdeler Joachim , Huppertz Andreas , Wember Kurt
Published: May 2007

Durch Umsetzung der 5‐Amino‐1.2.4‐thiodiazole mit Methyljodid oder durch Ringschluß‐Synthesen werden die im Kern methylierten Imino‐thiodiazoline erhalten. Die exocyclisch methylierten Amine sind über die 5‐Chlor‐Verbindung zugänglich, gelegentlich auch durch Umlagerung aus dem entsprechenden Thiodiazolin. Beide Klassen, von deren Hauptvertretern eine Anzahl Substitutions‐ und Abbauprodukte hergestellt wurden, unterscheiden sich charakteristisch in ihren Basizitäten, UV‐Spektren und Polarogrammen. Aus den Befunden wird geschlossen, daß die tautomeren 5‐Amino‐thiodiazole als Amine vorliegen.
Über Thiazole, XVIII. Mitteil.): Über die Synthese von 2‐[d‐gluco‐Pentaoxy‐pentyl]‐thiazolen
Authors: Beyer Hans , Schultz Ulrich
Published: May 2007

Es wird die Darstellung des 2‐[d‐gluco‐Pentaoxy‐pentyl]‐4‐phenyl‐thiazols beschrieben.

Aus der Literatur sind zahlreiche Verbindungen bekannt, bei denen der Einbau einer Zuckerkette in heterocyclische Ringsysteme in der Weise erfolgte, daß ein, zwei oder auch drei Kohlenstoffatome des Zuckermoleküls dem Heterocyclus angehören. Wir verweisen in diesem Zusammenhang auf das kürzlich erschienene Referat „Heterocyclische Verbindungen aus Zuckern”︁ von H. Vogel1). Danach und nach unserer Kenntnis ist es bisher nicht gelungen, einfache Zucker in den Thiazolkern einzubauen. Lediglich in einem Fall war es durch Kondensation von einfachen Zuckern mit Cystein möglich, zu Zuckerabkömmlingen der Thiazolidin‐carbonsäure (4)2) zu kommen.

Für die von uns geplanten Untersuchungen war die Arbeit von C. Neuberg und H. Wolff3) von Interesse, wonach bei der Einwirkung von Phenyl‐ bzw. Allyl‐senföl auf d‐Glucosamin in glatter Reaktion 1‐Phenyl (bzw. Allyl)‐2‐mercapto‐4‐[d‐arabo‐tetraoxy‐butyl]‐imidazol entsteht. Als Zwischenprodukt bildet sich hierbei N‐[Anilino‐thioformyl]‐[bzw. N‐(Allylamino‐thioformyl])‐d‐glucosamin, das anschließend unter Wasseraustritt in das Imidazolderivat übergeht. Demnach reagiert bei gleichzeitiger Anwesenheit einer Sulfhydryl‐ und einer sekundaren Aminogruppe bevorzugt die letztere. Würde sich die SH‐Gruppe an der Wasserabspaltung beteiligen, so müßte ein Thiazolylzucker entstehen, in dem die C‐Atome 1 und 2 des Glucosemoleküls dem Thiazolring angehören. Eine derartige Kondensation ließ sich bisher nicht realisieren. Ein weiteres Beispiel dafür, daß das lactolische Hydroxyl des Zuckers vornehmlich mit einer Aminogruppe reagiert, ist die Bildung des d‐Glucose‐thioharnstoffs4) aus der d‐Glucose und Thioharnstoff in Gegenwart von Salzsäure.
Über die Dien‐Synthese von Thiophenverbindungen mit Maleinsäure‐anhydrid (Mehrkernige Thiophene, II. Mitteil.)
Authors: Dann Otto , Kokorudz Michael , Gropper Robert
Published: May 2007

4.5;6.7‐Dibenzo‐isothionaphthen und das aus 2.5‐Dimethyl‐thiophen und Acetonylaceton in Fluorwasserstoff hergestellte 1.3.4.7‐ Tetramethyl‐isothionaphthen addieren Maleinsäure‐anhydrid. Nach diesem Verhalten bei der Dien‐Synthese und bei der Ultraviolettabsorption kann man das Ringsystem des Isothionaphthens zwischen dem des Anthracens und dem des Naphthalins einordnen.
Über Chlormethylchlorsilane
Authors: Runge Franz , Zimmermann Wolfgang
Published: May 2007

Es werden die Chlorderivate der drei möglichen Methyl‐chlorsilane dargestellt und beschrieben.

Die Chlorierung läßt sich beim Methyl‐trichlor‐silan leicht bis zum Ersatz aller Wasserstoffatome treiben, ohne daß Zwischenstufen gefaßt werden konnten, beim Dimethyl‐dichlor‐silan bis zur Substitution von fünf Wasserstoffatomen. Beim Trimethyl‐chlorsilan können maximal acht Wasserstoffatome ersetzt werden.

Das Sublimationsvermögen dieser Verbindungen ist an die Anwesenheit einer Trichlormethylgruppe im Molekül gebunden.
Die Alkaloide der Haemanthus‐Hybride „König Albert”︁ (IV. Mitteil. über Amaryllidaceen‐Alkaloide
Authors: Boit Hans‐G.
Published: May 2007

Aus der Haemanthus‐Hybride „König Albert”︁ werden Lycorin und zwei bisher nicht beschriebene Alkaloide Haemanthidin, C17H19O5N, und Haemanthamin, C17H19O4N isoliert.
Über die Substitution von Tosyloxy‐Gruppen durch Acetoxy‐Gruppen in Polyoxy‐Verbindungen. Eine neue Darstellungsweise von l‐Idose‐Derivaten aus d‐Glucose
Authors: Vargha L.
Published: May 2007

Es wurde der Austausch von Tosyloxy‐Gruppen gegen Acetoxy‐Gruppen in einigen Zucker‐Derivaten untersucht. Tosylester, welche die Tosyloxy‐Gruppe an einem Ring‐Kohlenstoffatom tragen, erwiesen sich unter den angewandten Reaktionsbedingungen als sehr beständig. Dagegen ließen sich die Tosyloxy‐Gruppen durch Acetoxy‐Gruppen in solchen Verbindungen ersetzen, in denen sie sich in der Seitenkette eines Furanose‐Ringes befinden.

Es wurde so ein neuer, ergiebiger präparativer Weg von der d‐Glucose zur l‐Idose gefunden. Die l‐Idose konnte nicht in kristallinem Zustand gewonnen werden; sie wandelte sich beim Aufbewahren allmählich in l‐Sorbose um.
Darstellung und Verhalten von Bicyclo‐[1.2.3]‐octen und Bicyclo‐[2.2.3]‐nonen Beiträge zur Kenntnis der Wagnerschen Umlagerung und der Phenylazid‐Reaktion
Authors: Alder Kurt , Krieger Hans , Weiβ Herbert
Published: May 2007

Durch vereinfachte Darstellungsmethoden werden das Bicyclo‐[1.2.3]‐octen‐(2) und das Bicyclo‐[1.2.3]‐octanol‐(2) zu leicht zugänglichen Verbindungen. Die Verfahren sind auch geeignet, die Reihe des Bicyclo‐[2.2.3]‐nonans zu erschließen. Bei der Hydratisierung nach Bertram‐Walbaum erleidet das Bicyclo‐[1.2.3]‐octen‐(2) eine Wagnersche Umlagerung und liefert das Bicyclo‐[2.2.2]‐octanol‐(2).

Sowohl das Bicyclo‐[1.2.3]‐octen‐(2) als auch das Bicyclo‐[2.2.3]‐nonen‐(2) zeigen bei der Phenylazid‐Reaktion nicht das Verhalten von Bicyclo‐[1.2.2]‐hepten‐Derivaten, sondern gleichen einfachen monocyclischen Olefinen.
Alkaloide von Sprekelia formosissima, Galanthus Elwesii, Zephyranthes candida und Crinum Powellii (VIII. Mitteil. über Amaryllidaceen‐Alkaloide1))
Authors: Boit Hans‐G. , Ehmke Horst
Published: May 2007

Es werden die folgenden Alkaloide isoliert: Aus Sprekelia formosissima Tazettin, Haemanthamin, Lycorin und Haemanthidin; aus Galanthus Elwesii Galanthamin, Lycorin, Tazettin und Haemanthamin; aus Zephyranthes candida Lycorin, Nerinin, Tazettin und Haemanthamin; aus Crinum Powellii Lycorin, Crinidin, Crinin, Crinamin und das bisher nicht beschriebene Powellin.
Synthesis of homogeneous anisotropic turbulent fields with prescribed second‐order statistics by the random spots method
Authors: Kornev Nikolai , Kröger Hannes , Hassel Egon
Published: May 2007

The problem of synthesis of homogeneous anisotropic turbulent fields with prescribed autocorrelation functions is solved using the method of random spots method (Commun. Numer. Meth. Engng 2007; 23:35–43). Every spot has an inner distribution f of a velocity component. The resulting velocity field is found as a sum of contributions from all spots. The inner distribution f is found from the condition that the resulting field has the prescribed statistical properties. The paper presents analytical solutions for f in the case of homogeneous turbulent fields. A numerical solution for the inhomogeneous case is discussed in (Commun. Numer. Meth. Engng 2007; 23:35–43). Copyright © 2007 John Wiley & Sons, Ltd.
APEX‐Map: a parameterized scalable memory access probe for high‐performance computing systems
Authors: Strohmaier Erich , Shan Hongzhang
Published: May 2007

The memory wall between the peak performance of microprocessors and their memory performance has become the prominent performance bottleneck for many scientific application codes. New benchmarks measuring data access speeds locally and globally in a variety of different ways are needed to explore the ever increasing diversity of architectures for high‐performance computing. In this paper, we introduce a novel benchmark, APEX‐Map, which focuses on global data movement and measures how fast global data can be fed into computational units. APEX‐Map is a parameterized, synthetic performance probe and integrates concepts for temporal and spatial locality into its design. Our first parallel implementation in MPI and various results obtained with it are discussed in detail. By measuring the APEX‐Map performance with parameter sweeps for a whole range of temporal and spatial localities performance surfaces can be generated. These surfaces are ideally suited to study the characteristics of the computational platforms and are useful for performance comparison. Results on a global‐memory vector platform and distributed‐memory superscalar platforms clearly reflect the design differences between these different architectures. Published in 2007 by John Wiley & Sons, Ltd.
Multi‐installment divisible load processing in heterogeneous distributed systems
Authors: Drozdowski M. , Lawenda M.
Published: May 2007

Divisible loads are parallel applications with fine granularity and negligible data dependencies. Such computations can be divided into parts of arbitrary sizes and processed independently in parallel. The load distribution process incurs considerable communication delays. To reduce processor waiting time during the computation initialization phase, the load is distributed in multiple small installments rather than in one big chunk. In this paper we analyze multi‐installment divisible load processing in heterogeneous distributed systems. Scheduling divisible loads in heterogeneous systems is hard because the sizes of the installments should be adjusted to the communication and computation capabilities of the system. We show that ignoring heterogeneity of the distributed system may result in arbitrarily bad solutions. Two algorithms are proposed to gear the load chunk sizes to different communication and computation speeds: an optimization branch‐and‐bound algorithm and a heuristic based on a genetic search method. The running times of both methods and the quality of the solutions are compared. Then, we use these algorithms to study the features of the multi‐installment divisible load scheduling problem. We demonstrate that it has both combinatorial and algebraic nature, and that optimum solutions are harder to find with the growing heterogeneity of the system. Copyright © 2007 John Wiley & Sons, Ltd.
Organic Electronic Devices and Their Functional Interfaces
Authors: Koch Norbert
Published: May 2007

A most appealing feature of the development of (opto)electronic devices based on conjugated organic materials is the highly visible link between fundamental research and technological advances. Improved understanding of organic material properties can often instantly be implemented in novel device architectures, which results in rapid progress in the performance and functionality of devices. An essential ingredient for this success is the strong interdisciplinary nature of the field of organic electronics, which brings together experts in chemistry, physics, and engineering, thus softening or even removing traditional boundaries between the disciplines. Naturally, a thorough comprehension of all properties of organic insulators, semiconductors, and conductors is the goal of current efforts. Furthermore, interfaces between dissimilar materials—organic/organic and organic/inorganic—are inherent in organic electronic devices. It has been recognized that these interfaces are a key for device function and efficiency, and detailed investigations of interface physics and chemistry are at the focus of research. Ultimately, a comprehensive understanding of phenomena at interfaces with organic materials will improve the rational design of highly functional organic electronic devices.
Synthesis, spectroscopic and anti‐tumor studies of polyphenol‐linoleates derived from natural polyphenols
Authors: Mustafa Jamal , Khan Shabana I. , Ferreira Daneel , Khan Ikhlas A.
Published: May 2007

An efficient first synthesis of di‐, hexa‐ and octa‐esters (octadeca‐Z‐9,12‐dienoates, linoleates) from natural 1,5‐bis‐(4'‐hydroxyphenyl)penta‐Z‐1,4‐diene (Ginkgo biloba L.), (–)‐epigallocatechin and (–)‐epigallocatechin‐3‐O‐gallate (jasmine tea/green tea), respectively, was developed. Using dicyclohexyl carbodiimide as an activating reagent in the presence of a catalytic amount of 4‐dimethylaminopyridine in polyesterification reactions gave di‐, hexa‐ and octa‐products (4), (7), and (8), respectively, in quantitative yields. A three‐step efficient procedure for the synthesis of 1,5‐bis‐[4'‐O‐(octadec‐Z‐9”,12”‐dienoate)phenyl]penta‐Z‐1,4‐diene (4) was also developed. The key step in the synthesis involved a stereo selective Wittig diolefination reaction that produced the penta‐Z‐1,4‐diene system of (4). 1H and 13C NMR and MS techniques confirmed the structures of the esters. The esterified compounds were tested for in vitro anti‐tumor activities against four and three human cancer cell lines at NCNPR and at NCI, respectively. They were found inactive as they failed to inhibit 50% growth of these cancer cells.
Analytical methods for determination of trans fatty acid content in food
Authors: Juanéda Pierre , Ledoux Martial , Sébédio Jean‐Louis
Published: May 2007

Adequate analytical tools are required for labelling food products for trans fatty acid (TFA) contents. The choice of the fatty acid (FA) derivatisation is a crucial step in obtaining good results, in particular with short‐chain and conjugated FA. Several gas chromatographic and infrared spectrophometric methods have been developed for analysing TFA in foods, some of which have been validated as official methods after collaborative studies. Complete analysis of total FA often requires the use of complementary high‐performance liquid chromatography methods. This paper reviews the analytical methods developed for identifying and quantifying TFA in foods and presents the official methods of analysis. Neither of these analytical methods enables a TFA naturally occurring in basic food to be distinguished from a TFA formed during an industrial process.
Domino [2+2]/[2+1] and [3+2]/[2+1] Reaction Sequences of Alkynyl(alkoxy) Chromium Fischer Carbene Complexes
Authors: Pérez‐Anes Alexandra , García‐García Patricia , Suárez‐Sobrino Ángel Luis , Aguilar Enrique
Published: May 2007

A tandem [2+2]/[2+1] sequence takes place between alkynyl(alkoxy) Fischer carbene complexes and 2,3‐dihydrofuran, producing three‐component adducts diastereoselectively in moderate yields. On the other hand, a [3+2]/[2+1] (1,3‐dipolar cycloaddition/cyclopropanation) sequence takes place between an alkynyl(alkoxy) Fischer carbene complex, trimethylsilyldiazomethane, and methyl acrylate or 2,3‐dihydrofuran. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
On the application of CZE to the study of protein denaturation
Authors: Piaggio Maria V. , Peirotti Marta B. , Deiber Julio A.
Published: May 2007

Experimental mobilities obtained from CZE are used to study protein denaturation through a model based on known physicochemical theories. This model is able to provide additional information concerning the folded and unfolded protein states from mobility data. Its use comprises first the evaluation of relevant parameters of the protein microstates like the electrostatic free energy, apart from the classical conformational free energy, and second the expression of raw experimental data concerning the folding–unfolding transition into more specific physicochemical parameters like protein hydrodynamic radius, net charge number, and hydration. Spurious effects that are intrinsic to the experimental evaluation of the mobility of protein states, like BGE viscosity, pH, and ionic strength variations accompanying the changes of the denaturant agent intensity are eliminated. In order to illustrate the proposal of this work, two case studies are considered here. The first one concerns thermal and urea denaturations of horse heart ferricytochrome c and the second one involves thermal denaturation of hen egg‐white lysozyme. Thus, relevant theoretical thermodynamic considerations of the folded–unfolded protein transition are presented, where the electrostatic free energy is included explicitly in the effective free energy. It is found that this transition involves sharp increases of hydrodynamic radius and protein hydration.
Microvariability in the early stages of cobble weathering by microenvironment on a glacier foreland, Storbreen, Jotunheimen, Norway
Authors: Thorn Colin E. , Darmody Robert G. , Campbell Sean W. , Allen Charles E. , Dixon John C.
Published: May 2007

The initial stages of cobble weathering, measured as increasing percentage porosity, were calculated for sets of cobbles taken from the foreland of Storbreen, a cirque glacier in the Jotunheimen, Norway. Cobbles were taken from in front of the 1998 glacier snout, from the 1928, 1870, 1810 and 1750 moraine crests and from the ∼10 000‐year‐old land surface beyond the Neoglacial foreland limit. Three microenvironments were examined within each site: (1) lichen‐free surfaces from exposed cobbles, (2) lichen‐covered surfaces from exposed cobbles and (3) buried cobbles taken from a soil depth of ∼40 cm. Percentage porosity within plagioclase minerals was calculated using backscatter electron images of prepared thin sections. Porosity was calculated from five depth profiles into each cobble. Depth profiles were subdivided into a sequence of 50 µm × 50 µm rectangles running to at least a nominal depth of 500 µm within each cobble. Three cobbles from each dated land surface were sampled, except for the 1750 surface, which had five cobbles. Statistical analysis was by analysis of variance of rank‐order transformed data. Findings indicate that cobbles close to the glacier snout are largely unweathered; also, weathering is generally weak in the 1928, 1870 and 1810 positions, but statistically significantly higher in the 1750‐ and 10 000‐year‐old positions. Weathering of buried cobbles always exceeded weathering of exposed cobbles and may possibly reach a value beyond which it cannot progress while retaining surface cohesion. The degree of weathering on lichen‐free and lichen‐covered cobble surfaces is not initially distinguishable, but diverges sharply after ∼250 years, when lichen‐covered surfaces experience significantly higher totals. Overall, the weathering trend in cobbles matches that found in soils at the same sites. Copyright © 2007 John Wiley & Sons, Ltd.
Darwinian origin of landforms
Authors: Corenblit Dov , Steiger Johannes , Gurnell Angela , Tabacchi Eric
Published: May 2007

Whilst earth surface landforms evolve largely as a result of the activity of certain living organisms, the biologically driven geomorphic changes have evolutionary consequences on organisms and ecological communities. Recognition of complex biotic–abiotic feedbacks may lead to deep changes in our understanding of geomorphology. Copyright © 2007 John Wiley & Sons, Ltd.
The pricing of foreign currency options under jump‐diffusion processes
Authors: Ahn Chang Mo , Cho D. Chinhyung , Park Keehwan
Published: May 2007

In this article, the authors derive explicit formulas for European foreign exchange (FX) call and put option values when the exchange rate dynamics are governed by jump‐diffusion processes. The authors use a simple general equilibrium international asset pricing model with continuous trading and frictionless international capital markets. The domestic and foreign price level are introduced as state variables that contain jumps caused by monetary shocks and catastrophic events such as 9/11 or Hurricane Katrina. The domestic and foreign interest rates are stochastic and endogenously determined in the model and are shown to be critically affected by the jump risk of the foreign exchange. The model shows that the behavior of FX options is affected through the impact of state variables and parameters on the nominal interest rates. The model contrasts with those of M. Garman and S. Kohlhagen (1983) and O. Grabbe (1983), whose models have exogenously determined interest rates. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:669–695, 2007
Using relative distributions to investigate the body mass index in England and Canada
Authors: Contoyannis Paul , Wildman John
Published: May 2007

In this paper we use relative distributions to examine changes in the distribution of the body mass index (BMI) in England and Canada during the period 1994/5–2000/1. The use of relative distributions allows us to describe changes in the whole distribution of the BMI in a non‐parametric fashion. While statistics analogous to the Gini index can be constructed based on the relative distribution, important characteristics of changes in the distribution of the BMI such as changes in the proportions overweight and obese are more naturally handled using measures of relative polarization. Our results show that while BMI has increased in both countries, BMI in England has increased at a much faster rate than in Canada. Both groups show polarization over time towards both tails of the weight distribution, with the English polarizing towards the upper tail at a faster rate than Canadians. Copyright © 2007 John Wiley & Sons, Ltd.
Resveratrol and trimethylated resveratrol protect from acute liver damage induced by CCl4 in the rat
Authors: Rivera Horacio , Shibayama Mineko , Tsutsumi Victor , Perez‐Alvarez Victor , Muriel Pablo
Published: May 2007

The importance of hydroxyl groups in the antioxidant and hepatoprotective properties of resveratrol was investigated. To achieve this, resveratrol or its trimethylated analog were administered (10 mg kg−1, p.o.) to male Wistar rats and liver damage was induced by acute administration of CCl4 (4 g kg−1, p.o.); appropriate controls were performed. The animals were killed 24 h after CCl4 intoxication. The amount of reduced glutathione (GSH) in the liver was not modified by any treatment; interestingly, the GSH/GSSG (oxidized glutathione) ratio decreased in the groups receiving CCl4 and resveratrol associated with an increase in GSSG. In blood GSH and the GSH/GSSG ratio were decreased by CCl4; both effects were completely prevented by any of the compounds tested. Lipid peroxidation and the activity of γ‐glutamyl transpeptidase were increased significantly after CCl4. Resveratrol partially prevented these increases and surprisingly, trimethylated resveratrol completely prevented the increase of these markers. Both compounds partially but significantly prevented the increase in the activity of alanine aminotransferase; this result agrees with observations in the histological analysis. Both tested compounds administered alone produced no effect. The results of the present study suggest that OH groups are important for the antioxidant and hepatoprotective properties of the molecule of resveratrol; nevertheless, these effects can be improved by replacing hydrogen by a methyl in these groups. The differences in the antioxidant and hepatoprotective effects of these compounds could be due to the possibility that the trimethylated resveratrol acts like a prodrug, prolonging, probably, the half‐life of the original compound. Copyright © 2007 John Wiley & Sons, Ltd.
In vitro and in vivo antitumor effect of 5‐FU combined with piplartine and piperine
Authors: Bezerra Daniel P. , Castro Fernanda O. de , Alves Ana Paula N. N. , Pessoa Cláudia , Moraes Manoel Odorico de , Silveira Edilberto R. , Lima Mary Anne S. , Elmiro Francisca Juliana M. , Alencar Nylane M. N. de , Mesquita Rodney O. , Lima Michael W. , Costa‐Lotufo Letícia V.
Published: May 2007

It has been reported that piplartine and piperine, alkaloid/amide compounds from Piper species, show antitumor activities. In the present paper, the effects of the combination of 5‐fluorouracil (5‐FU) with piplartine or piperine was determined using in vitro and in vivo experimental models. Hematological and biochemical analyses, as well as histopathological and morphological analyses of the tumor and the organs, including liver, spleen and kidney, were performed in order to evaluate the toxicological aspects associated with different treatments. The incubation of tumor cell lines with 5‐FU in the presence of piplartine or piperine produced an increase in growth inhibition, as observed by lower IC50 values for 5‐FU. These effects were also observed in vivo, where the combination with piplartine but not piperine with 5‐FU led to a higher tumor growth inhibition. The results indicated that either piplartine‐ or 5‐FU‐treated animals showed a low inhibition rate when they were used individually at low doses of 28.67% and 47.71%, respectively, but when they were combined at the same dose, the inhibition rate increased significantly to 68.04%. The histopathological analysis showed that the livers and the kidneys of treated animals were only slightly and reversibly affected. Neither the enzymatic activity of transaminases nor the urea levels were significantly modified when compared with the control group. Hematological analysis showed leukopenia after 5‐FU treatment, which was reversed by the combined use of piplartine and piperine. These findings indicate that piplartine may enhance the therapeutic effectiveness of chemotherapeutic drugs, and moreover, this combination could improve immunocompetence hampered by 5‐FU. Copyright © 2007 John Wiley & Sons, Ltd.
Pristimerin induces apoptosis by targeting the proteasome in prostate cancer cells
Authors: Yang Huanjie , Landis‐Piwowar Kristin R. , Lu Dayan , Yuan Ping , Li Lihua , Reddy G. Prem‐Veer , Yuan Xiao , Dou Q. Ping
Published: May 2007

Pristimerin is a natural product derived from the Celastraceae and Hippocrateaceae families that were used as folk medicines for antiinflammation in ancient times. Although it has been shown that pristimerin induces apoptosis in breast cancer cells, the involved mechanism of action is unknown. The purpose of the current study is to investigate the primary target of pristimerin in human cancer cells, using prostate cancer cells as a working model. Nucleophilic susceptibility and in silico docking studies show that C6 of pristimerin is highly susceptible towards a nucleophilic attack by the hydroxyl group of N‐terminal threonine of the proteasomal chymotrypsin subunit. Consistently, pristimerin potently inhibits the chymotrypsin‐like activity of a purified rabbit 20S proteasome (IC50 2.2 µmol/L) and human prostate cancer 26S proteasome (IC50 3.0 µmol/L). The accumulation of ubiquitinated proteins and three proteasome target proteins, Bax, p27 and IκB‐α, in androgen receptor (AR)‐negative PC‐3 prostate cancer cells supports the conclusion that proteasome inhibition by pristimerin is physiologically functional. This observed proteasome inhibition subsequently led to the induction of apoptotic cell death in a dose‐ and kinetic‐dependent manner. Furthermore, in AR‐positive, androgen‐dependent LNCaP and AR‐positive, androgen‐independent C4‐2B prostate cancer cells, proteasome inhibition by pristimerin results in suppression of AR protein prior to apoptosis. Our data demonstrate, for the first time, that the proteasome is a primary target of pristimerin in prostate cancer cells and inhibition of the proteasomal chymotrypsin‐like activity by pristimerin is responsible for its cancer cell death‐inducing property. J. Cell. Biochem. 103: 234–244, 2008. © 2007 Wiley‐Liss, Inc.
Angiogenesis by transplantation of HIF‐1α modified EPCs into ischemic limbs
Authors: Jiang Meng , Wang Binyao , Wang Changqian , He Ben , Fan Huahua , Guo Taylor B. , Shao Qin , Gao Li , Liu Yan
Published: May 2007

Hypoxia inducible factor‐1α (HIF‐1α) is a key determinant of oxygen‐dependent gene regulation in angiogenesis. HIF‐1α overexpression may be beneficial in cell therapy of hypoxia‐induced pathophysiological processes, such as ischemic heart disease. To address this issue, human peripheral blood mononuclear cells (PBMNCs) were induced to differentiate into endothelial progenitor cells (EPCs), and then were transfected with either an HIF‐1α‐expressing or a control vector and cultured under normoxia or hypoxia. Hypoxia‐induced HIF‐1α mRNA and protein expression was increased after HIF‐1α transfection. This was accompanied by VEGF mRNA induction and increased VEGF secretion. Hypoxia‐stimulated VEGF mRNA induction was significantly abrogated by HIF‐1α‐specific siRNA. Functional studies showed that HIF‐1α overexpression further promoted hypoxia‐induced EPC differentiation, proliferation and migration. The expressions of endothelial cell markers CD31, VEGFR2 (Flk‐1) and eNOS as well as VEGF and NO secretions were also increased. Furthermore, in an in vivo model of hindlimb ischemia, HIF‐1α‐transfected EPCs homed to the site of ischemia. A higher revascularization potential was also demonstrated by increased capillary density at the injury site. Our results revealed that endothelial progenitor cells ex vivo modification by hypoxia inducible factor‐1α gene transfection is feasible and may offer significant advantages in terms of EPC expansion and treatment efficacy. J. Cell. Biochem. 103: 321–334, 2008. © 2007 Wiley‐Liss, Inc.
Cancer stem cells in leukemia, recent advances
Authors: Zou Gang‐Ming
Published: May 2007

The history of stem cell research was started in the early 1900s in Europe where the researcher realized that various types of blood cells came from a particular “stem cells.” However, it was not until 1963 that the first quantitative description of the self‐renewal activities of transplanted mouse bone marrow cells were documented by Canadian scientist Ernest A McCulloch and James E Till in Toronto. The concept of cancer stem cells has been used over 50 years ago; whereas the strong evidence for the existence of a Cancer Stem Cells was obtained recently. Consequently, there is increasing attention in recent year about cancer stem cells. The findings from recent studies support the concept that stem cells are integral to the development of several forms of human cancer. Changes in stem cell behavior can contribute to tumor formation. Leukemia is a cancer of blood‐forming tissue, including the bone marrow and lymphatic system. Leukemic stem cells represent the cancer stem cells in the leukemia. In this review, we summarize the recent advance in the study of leukemic stem cells. J. Cell. Physiol. 213: 440–444, 2007. © 2007 Wiley‐Liss, Inc.
Microfluidic selection and applications of aptamers
Authors: Mosing Renee K. , Bowser Michael T.
Published: May 2007

The high affinity and specificity of aptamers make them ideal reagents for a wide range of analytical applications. It is not surprising that they are finding application in microfluidics as well. CE has proven to be an efficient technique for isolating aptamers. Aptamers have been used as affinity reagents in CE assays. Aptamer‐based chromatography stationary phases have demonstrated unique selectivities. Possibly the application that holds the highest potential is aptamer microarrays for screening proteomic samples.
Recent applications in nanoliquid chromatography
Authors: Hernández‐Borges Javier , Aturki Zeineb , Rocco Anna , Fanali Salvatore
Published: May 2007

Since its first introduction by Karlsson and Novotny in 1988 nano‐LC has emerged as a complementary and/or competitive separation method to conventional HPLC, offering several advantages such as higher efficiency, ability to work with minute sample sizes and lower consumption of mobile phases, and better compatibility with MS, etc. Although its use was not so extended initially, in the last years new and interesting applications have appeared which deserve to be carefully considered. The aim of this review is therefore to provide an updated and critical survey of different nano‐LC applications in analytical chemistry.
Optical coherence tomography imaging depth enhancement by superficial skin optical clearing
Authors: Proskurin S G , Meglinski I V
Published: May 2007

Non-invasive imaging of human skin and human skin tissues by optical coherence tomography (OCT) is a field exciting a great deal of interest especially in terms of day-to-day medical and biomedical diagnostics. We develop rapid scanning OCT system for non-invasive real-time imaging of topical skin tissues in vivo. We investigate the possibility of OCT image enhancement along the transcutaneous diffusion into the skin an optical clearing agent. Diffusion of optical clearing agents, e.g. such as glycerol, temporary increases transparency of topical skin tissues that allows for unrestricted sounding radiation permeating deeper into the skin. Increasing transparency of superficial skin tissues significantly improves depth of imaging, image contrast and spatial resolution. Thus, topical optical clearing of skin enable applying low power light source (0.5 – 0.2 mW) and achieve the probing depth up to 1.5 – 1.7 mm. Current approach is able providing images of superficial human blood vessels 0.2 – 1 mm in diameter that are not visible by conventional OCT at normal conditions. The presented results illustrate, for the first time of our knowledge, the images of topical skin vessels with 12 μm spatial resolution before and after optical clearing.
PLA Nano‐ and Microparticles for Drug Delivery: An Overview of the Methods of Preparation
Authors: Lassalle Verónica , Ferreira María Luján
Published: May 2007

The controlled release of medicaments remains the most convenient way of drug delivery. Therefore, a wide variety of reports can be found in the open literature dealing with drug delivery systems. In particular, the use of nano‐ and microparticles devices has received special attention during the past two decades. PLA and its copolymers with GA and/or PEG appear as the preferred substrates to fabricate these devices. The methods of fabrication of these particles will be reviewed in this article, describing in detail the experimental variables associated with each one with regard to the influence of them on the performance of the particles as drug carriers. An analysis of the relationship between the method of preparation and the kind of drug to encapsulate is also included. Furthermore, certain issues involved in the addition of other monomeric substrates than lactic acid to the particles formulation as well as novel devices, other than nano‐ and microparticles, will be discussed in the present work considering the published literature available.

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Capturing Relativized Complexity Classes without Order
Authors: Dawar Anuj , Gottlob Georg , Hella Lauri
Published: May 2007

We consider the problem of obtaining logical characterisations of oracle complexity classes. In particular, we consider the complexity classes LOGSPACENP and PTIMENP. For these classes, characterisations are known in terms of NP computable Lindström quantifiers which hold on ordered structures. We show that these characterisations are unlikely to extend to arbitrary (unordered) structures, since this would imply the collapse of certain exponential complexity hierarchies. We also observe, however, that PTIMENP can be characterised in terms of Lindström quantifers (not necessarily NP computable), though it remains open whether this can be done for LOGSPACENP.
Extracting Algorithms from Intuitionistic Proofs
Authors: Ferreira Fernando , Marques António
Published: May 2007

This paper presents a new method ‐ which does not rely on the cut‐elimination theorem ‐ for characterizing the provably total functions of certain intuitionistic subsystems of arithmetic. The new method hinges on a realizability argument within an infinitary language. We illustrate the method for the intuitionistic counterpart of Buss's theory S, and we briefly sketch it for the other levels of bounded arithmetic and for the theory IΣ1.
Generalizing Morley's Theorem
Authors: Hyttinen Tapani
Published: May 2007

We study the categoricity of the classes of (possibly slightly saturated) elementary submodels of a homogeneous structure.
Games with Unknown Past
Authors: Khoussainov Bakhadyr , Yakhnis Alexander , Yakhnis Vladimir
Published: May 2007

We define a new type of two player game occurring on a tree. The tree may have no root and may have arbitrary degrees of nodes. These games extend the class of games considered by Gurevich‐Harrington in [5]. We prove that in the game one of the players has a winning strategy which depends onfinite bounded information about the pastpart of a play and on future of each play that isisomorphism typesof tree nodes. This result extends further the Gurevich‐Harrington determinacy theorem from [5].
Dynamics of Polymer Networks with Strong Differences in the Viscous Characteristics of their Crosslinks and Strands
Authors: Toshchevikov Vladimir P. , Blumen Alexander , Gotlib Yulii Ya.
Published: May 2007

We study theoretically the relaxation properties of polymer networks, whose monomers and junction sites have different friction parameters (ζ and ζjun, respectively). For this, we focus on topologically regular cubic networks built from “bead‐and‐spring” Rouse chains. Setting σ = ζjun/ζ, we determine analytically both the eigenvalues and the eigenmodes of the model for arbitrary values of σ. This allows us to extend previous approaches (Macromolecules 2000, 33, 6578) which were restricted by the condition σ = 3. We compute the frequency dependent storage, G′(ω), and loss, G″(ω), moduli (which for σ ≫ 3 or σ ≪ 3 display two plateaus and two maxima, respectively) and also the mean‐square displacements of the network junctions and of the beads; these turn out to obey power laws, whose validity ranges depend on σ.

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