bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorierungen organischer Verbindungen mit Chlortrifluorid, IV. Zur Umsetzung von Chloroform und 1.1‐Difluor‐1.2.2‐trichloräthan (F 122) mit Chlor oder Chlortrifluorid in der Gasphase
Authors: Cornils Boy , Eckermann Reiner , Schiemann Günther 
Published: June 2007

AbstractChloroform und 1.1‐Difluor‐1.2.2‐trichlor‐äthan (F 122)F 122 (= Frigen 122) als Kurzbezeichnung entspr. Frigen, Freon, Kaltron u. ä. Handelsbezeichnungen®.
wurden zwischen 100 und 270° mit ClF3 und zum Vergleich mit elementarem Chlor in der Gasphase umgesetzt. Chloroform reagierte sowohl mit Cl2 als auch mit ClF3 leichter als F 122. Bei der Halogenierung von F 122 macht sich der stabilisierende Einfluß von Halogenatomen in α‐Stellung zum substituierbaren H‐Atom bemerkbar. Chloroform wird durch ClF3 lediglich fluoriert. Bei der H‐Substitution von F 122 betrug das Verhältnis Cl: F der aus dem ClF3 stammenden Halogene in den Reaktionsprodukten etwa 1 : 1, so daß der Rest des Fluors als HF verlorenging. Dies gilt bei vielen organischen Verbindungen für die Halogenierung mit ClF3.
N‐Isogramin und einige verwandte N‐Mannich‐Basen des Indols
Authors: Swaminathan Sambasiva , Narasimhan Krishnaiyer 
Published: June 2007

AbstractN‐Isogramin (N‐Dimethylaminomethyl‐indol) und drei weitere verwandte N‐Mannich‐Basen des Indols wurden neben relativ wenig 3‐Dialkylaminomethyl‐ und 1.3‐Bis‐dialkylamino‐methyl‐indolen durch Mannich‐Reaktion in Abwesenheit von Essigsäure gewonnen. N‐Isogramin isomerisiert unter verschiedenen Bedingungen zu Gramin. Versuche, N‐substituierte Indole durch normale Alkylierung von 2‐Methyl‐cyclohexandion‐(1.3) oder Acetamino‐malonsäure‐diäthylester mit N‐Isogramin oder dessen Methosulfat zu gewinnen, erbrachten statt dessen die isomeren 3‐substituierten Indole.
Alkali‐Phosphorverbindungen und ihr reaktives Verhalten, XL. Reaktion der Alkaliphosphide mit Bis‐[α‐chlor‐benzyliden]‐hydrazin
Authors: Issleib Kurt , Balszuweit Arno 
Published: June 2007

AbstractP‐Substituierte Alkaliphosphide MePR2 und Me2PR reagieren mit Bis‐[α‐chlor‐benzyliden]‐hydrazin zu Bis‐[α‐phosphino‐benzyliden]‐hydrazinen C6H5(R2P)CNNC(PR2)C6H5 (RC6H5, c‐C6H11) und zu 1.2.5‐Triphenyl‐1.3.4‐phosphadiazol. Letzteres entsteht auch aus C6H5(K)PP(K)C6H5 infolge einer Disproportionierungsreaktion. Als Folge eines Redoxvorganges entstehen außerdem Benzonitril und Tetraorgano‐biphosphine bzw. Cyclo‐phosphine. Die dargestellten Phosphorverbindungen besitzen unterschiedliches Reaktionsverhalten gegenüber Schwefel und Wasser. Ihre IR‐Spektren werden diskutiert.
Über die SiS‐Bindung, II. Eine neue Thiolestersynthese
Authors: Rimpler Manfred 
Published: June 2007

AbstractTrimethylsilylmercapto‐carbonsäureesterDer Trimethylsilylrest wird als silylgruppe bezeichnet.
setzen sich mit Säurechloriden zu S‐acylierten Produkten um. Die Esterbindung bleibt unverändert, läßt sich aber anschließend im Falle eines Silylesters leicht hydrolytisch spalten. Dabei entstehen Si‐freie Thiolester R–COS–R′.
Über Alkoxide des Bleis, II. Reaktion von Trialkylbleimethoxiden mit Diboran; Darstellung von Trialkylplumbanen und Trialkylbleiboranaten
Authors: Amberger Eberhard , Hönigschmid‐Grossich Rüdiger 
Published: June 2007

AbstractBei der Umsetzung von Trialkylbleimethoxiden mit Diboran entstehen in fast quantitativer Ausbeute bis −35° stabile Trialkylbleiboranate. Bei deren Methanolyse bei −78° scheiden sich die Trialkylplumbane als schwere, farblose Öle ab. Sie beginnen ab etwa −20° zu zerfallen, wobei die Zerfallsgeschwindigkeit mit größer werdender Alkylgruppe abnimmt. Trimethylbleiboranat hingegen zerfällt in ätherischer Suspension schon bei −78° langsam in Trimethylplumban und Diboran.
Spektroskopische Untersuchungen an Polymethincarboniumsalzen und Polyencarbinolen
Authors: Sondermann Joachim , Kuhn Hans 
Published: June 2007

AbstractDie Verbindungen der Reihen
equation image
werden dargestellt. In beiden Reihen stimmen die λmax‐Werte und die Oszillatorenstärken der Banden im Elektronenspektrum mit den nach der Elektronengasmethode berechneten Werten gut überein.
Theory and practical understanding of the migration behavior of proteins and peptides in CE and related techniques
Authors: Freitag Ruth , Hilbrig Frank 
Published: June 2007

AbstractCEC is defined as an analytical method, where the analytes are separated on a chromatographic column in the presence of an applied voltage. The separation of charged analytes in CEC is complex, since chromatographic interaction, electroosmosis and electrophoresis contribute to the experimentally observed behavior. The putative contribution of effects such as surface electrodiffusion has been suggested. A sound theoretical treatment incorporating all effects is currently not available. The question of whether the different effects contribute in an independent or an interdependent manner is still under discussion. In this contribution, the state‐of‐the‐art in the theoretical description of the individual contributions as well as models for the retention behavior and in particular possible dimensionless ‘retention factors’ is discussed, together with the experimental database for the separation of charged analytes, in particular proteins and peptides, by CEC and related techniques.
Some new bibds with k = 6 and λ = 1
Authors: Abel R. J. R. , Mills W. H. 
Published: June 2007

Abstract(v, 6,1) BIBDs are given for several new values of v. This reduces to 55 the number of v values for which existence of a (v,6,1) BIBD is in doubt. A new resolvable (565,5,1) BIBD is also given. © 1995 John Wiley & Sons, Inc.
Proper S(t, K,v)'s for t ≥ 3,v ≤ 16, |K| > 1 and Their Extensions
Authors: Kramer E. S. , Mathon Rudolf 
Published: June 2007

AbstractWe characterize the proper t‐wise balanced designs t‐(v,K,1) for t ≥ 3, λ = 1 and v ≤ 16 with at least two block sizes. While we do not examine extensions of S(3,4,16)'s, we do determine all other possible extensions of S(3,K,v)'s for v ≤ 16. One very interesting extension is an S(4, {5,6}, 17) design.©1995 John Wiley & Sons, Inc.
Quasi‐Symmetric Designs with Good Blocks
Authors: McDonough T. P. , Mavron V. C. 
Published: June 2007

AbstractThe article is concerned with a characterization of quasi‐symmetric (QS) designs with intersection numbers 0 and y. It uses the idea of a good block. Such a block G has the property that for any block B with |G ∩ B| = y, every point is on a block containing G ∩ B. It is proved that if a QS design II with intersection numbers 0 and y has a good block, then II must (i) be affine, symmetric, a linear space or (ii) have one of two possible exceptional parameter sets. Only one example is known in case (ii). If all blocks of II are good and II is not a linear space, then it is a projective or affine geometry or it is an extension (in a more general sense than usual) of a projective plane of order y2 or y3+ y. © 1995 John Wiley & Sons, Inc.
Regulation of GLUT3 and glucose uptake by the cAMP signalling pathway in the breast cancer cell line ZR‐75
Authors: Meneses Ana Maria , Medina Rodolfo A. , Kato Sumie , Pinto Mauricio , Jaque Maria Paz , Lizama Isabel , García María de los Ángeles , Nualart Francisco , Owen Gareth I. 
Published: June 2007

AbstractIncreased glucose uptake as a principal energy source is a requirement for the continued survival of tumour cells. Facilitative glucose transporter‐1 (GLUT1) and ‐3 (GLUT3) have been previously shown to be present and regulated in breast cancer cells and are associated with poor patient prognosis. In cancer cells, the cAMP secondary messenger pathway is known to potentiate described glucose transporter activators and regulate cell fate. However, no regulation of the glucose transporters in breast cancer cells by cAMP has previously been examined. Herein, we determined in the well‐characterized breast cancer cell line ZR‐75, if the cAMP analogue 8‐br‐cAMP was capable of regulating GLUT1 and GLUT3 expression and thus glucose uptake. We demonstrated that 8‐br‐cAMP transiently up‐regulates GLUT3 mRNA levels. The use of actinomycin‐D and the cloning of 1,200 bp upstream of the human GLUT3 promoter demonstrated that this regulation was transcriptional. Immunocytochemistry and Western blotting confirmed that the increase in mRNA was reflected by an increase in protein levels. No notable regulation of GLUT1 in the presence of 8‐br‐cAMP was detected. Finally, we determined using the non‐metabolizable glucose analogue 2‐DOG if this up‐regulation in GLUT3 increased glucose uptake. We observed the presence of two uptake components, one corresponding to the Km of GLUT1/4 and the other to GLUT3. A doubling in the uptake velocity was observed only at the Km corresponding to GLUT3. In conclusion, we demonstrate and characterize for the first time, an up‐regulation of GLUT3 mRNA, protein and glucose uptake by the cAMP pathway in breast cancer cells. J. Cell. Physiol. 214:110–116, 2008. © 2007 Wiley‐Liss, Inc.
Equimatchable factor‐critical graphs
Authors: Favaron Odile 
Published: June 2007

AbstractA simple graph G(X, E) is factor‐critical if the induced subgraph 〈X – x〉 admits a perfect matching for every vertex x of G. It is equimatchable if every maximal matching of G is maximum. The equimatchable non‐factor‐critical graphs have been studied by Lesk, Plummer, and Pulleyblank. In this paper, we study the equimatchable factor‐critical graphs; in particular we show that if such a graph is two‐connected, it is hamiltonian.
A note on chromatic uniqueness of graphs
Authors: Chia G. L. 
Published: June 2007

AbstractWe proved that if a connected graph is chromatically unique, then it has at most two blocks. Furthermore each of these blocks is vertex‐transitive and chromatically unique. It is then shown that if the two blocks of a connected graph G are H and K2, then G is chromatically unique if and only if H is vertex‐transitive and chromatically unique. This answers a conjecture of Whitehead and Zhao in the affirmative.
Every connected graph is a query graph
Authors: Winkler Peter M. 
Published: June 2007

AbstractLet V be a set of bit strings of length k, i.e., V ⊂ {0, 1}k. The query graph Q(V) is defined as follows: the vertices of Q(V) are the elements of V, and {ū, v̄} is an edge of Q(V) if and only if no other w̄ ϵ V agrees with ū in all the positions in which v̄ does. If V represents the set of keys for a statistical data base in which queries that match only one key are rejected, then the security of the individual data is related to the graph Q(V).Ernst Leiss showed that graphs belonging to any of several classes could be represented as query graphs and asked whether any connected graph could be so represented. We answer his question in the affirmative by making use of a spanning tree with special properties.
Highly irregular graphs
Authors: Alavi Yousef , Chartrand Gary , Chung F. R. K. , Erdös Paul , Graham R. L. , Oellermann Ortrud R. 
Published: June 2007

AbstractA connected graph is highly irregular if each of its vertices is adjacent only to vertices with distinct degrees. In this paper we investigate several problems concerning the existence and enumeration of highly irregular graphs as well as their independence numbers, with particular focus on the corresponding problems for highly irregular trees.
On 3‐colorings of bipartite p‐threshold graphs
Authors: Tomescu Ioan 
Published: June 2007

AbstractIn this paper some extremal properties of 3‐colorings of bipartite complete graphs in the class of all bipartite p‐threshold graphs that are uniquely 2‐colorable are proved. As a consequence it is shown that the complete bipartite graphs Kp, p + r where p ⩾ 2 and 0 ⩽ r <magnified image are chromatically unique. A useful result concerning the maximization of a sum of powers of two under certain restrictions, which has an arithmetical interest, is also presented.
Subgraphs of large connectivity and chromatic number in graphs of large chromatic number
Authors: Alon N. , Kleitman D. , Thomassen C. , Saks M. , Seymour P. 
Published: June 2007

AbstractFor each pair k, m of natural numbers there exists a natural number f(k, m) such that every f(k, m)‐chromatic graph contains a k‐connected subgraph of chromatic number at least m.
Unretractive and S‐unretractive joins and lexicographic products of graphs
Authors: Knauer Ulrich 
Published: June 2007

AbstractGraphs without proper endomorphisms are the subject of this article. It is shown that the join of two graphs has this property if and only if both summands have it, and that the lexicographic product of a complete graph or an odd circuit as first factors has this property if and only if the second factor has it. A somewhat stronger theorem is proved if the lexicographic product has no proper strong endomorphism. The corresponding result for the join is the same as for usual endomorphisms.
Reconstruction of locally finite connected graphs with at least three infinite wings
Authors: Nash‐Williams C. St. J. A. 
Published: June 2007

AbstractLet G be a locally finite connected graph that can be expressed as the union of a finite subgraph and p disjoint infinite subgraphs, where 3 ≦ p < ∞, but cannot be expressed as the union of a finite subgraph and p + 1 disjoint infinite subgraphs. Then G is reconstructible.
Extremal problems involving neighborhood unions
Authors: Faudree Ralph J. , Gould Ronald J. , Jacobson Michael S. , Schelp Richard H. 
Published: June 2007

AbstractWe examine several extremal problems for graphs satisfying the property |N(x) ∪ N(y)| ⩾ s for every pair of nonadjacent vertices x, y ϵ V(G). In particular, values for s are found that ensure that the graph contains an s‐matching, a 1‐factor, a path of a specific length, or a cycle of a specific length.
On the presence of disjoint subgraphs of a specified type
Authors: Thomassen Carsten 
Published: June 2007

AbstractWe say that a graph family ℱ has the Erdös‐Pósa property if there exists a function f(k) such that any graph G contains either k disjoint subgraphs each isomorphic to a member of ℱ, or contains a set S of at most f(k) vertices such that G — S contains no graph in ℱ. We derive a general sufficient condition for a family of graphs to have the Erdös‐Pósa property. In particular, for any fixed natural number m the collection of cycles of length divisible by m has the Erdös‐Pósa property. As a by‐product, we obtain a polynomially bounded algorithm for finding a cycle of length divisible by m. On the other hand, we describe a general class of planar graphs H such that a collection of subdivisions of H does not have the Erdös‐Pósa property. In fact, H may even be a tree.
Cutting a graph into two dissimilar halves
Authors: Erdós Paul , Goldberg Mark , Pach János , Spencer Joel 
Published: June 2007

AbstractGiven a graph G and a subset S of the vertex set of G, the discrepancy of S is defined as the difference between the actual and expected numbers of the edges in the subgraph induced on S. We show that for every graph with n vertices and e edges, n < e < n(n − 1)/4, there is an n/2‐element subset with the discrepancy of the order of magnitude of \documentclass{article}\pagestyle{empty}\begin{document}$\sqrt {ne}$\end{document} For graphs with fewer than n edges, we calculate the asymptotics for the maximum guaranteed discrepancy of an n/2‐element subset. We also introduce a new notion called “bipartite discrepancy” and discuss related results and open problems.
A sufficient condition for a bipartite graph to have a k‐factor
Authors: Enomoto Hikoe , Ota Katsuhiro , Kano Mikio 
Published: June 2007

AbstractP. Katerinis obtained a sufficient condition for the existence of a 2‐factor in a bipartite graph, in the spirit of Hall's theorem. We show a sufficient condition for the existence of a k‐factor in a bipartite graph, as a generalization of Katerinis's theorem and Hall's theorem.
Transforming trees by successive local complementations
Authors: Bouchet André 
Published: June 2007

AbstractA local complementation of a simple graph G at a vertex v consists in replacing the subgraph induced by G on the neighborhood of v by the complementary graph. Two graphs are locally equivalent if they are related by a sequence of local complementations. H. M. Mulder conjectured that any two locally equivalent trees are isomorphic. We prove this conjecture and we characterize those graphs that are locally equivalent to trees.
Hamilton cycles in claw‐free graphs
Authors: Zhang Cun‐Quan 
Published: June 2007

AbstractBondy conjectured that if G is a k‐connected graph of order n such that
magnified image
for any (k + 1)‐independent set / of G, then the subgraph outside any longest cycle contains no path of length k − 1. In this paper, we are going to prove that, if G is a k‐connected claw‐free (K1,3‐free) graph of order n such that
magnified image
for any (k + 1)‐independent set /, then G contains a Hamilton cycle. The theorem in this paper implies Bondy's conjecture in the case of claw‐free graphs.
On maximal independent sets of nodes in trees
Authors: Meir A. , Moon J. W. 
Published: June 2007

AbstractA subset / of the nodes of a graph is a maximal independent set if no two nodes of / are joined to each other and every node not in / is joined to at least one node in /. We investigate the behavior of the average numbere(n) and the average size μ(n) of maximal independent sets in treesTnwhere the averages are over all treesTnbelonging to certain families of rooted trees. We find, under certain conditions, thate(n) ∼q·Enand μ(n) ∼Snasn→ ∞, whereq,E, andSare constants that depend on the family being considered.
Threshold tolerance graphs
Authors: Monma Clyde L. , Reed Bruce , Trotter William T. 
Published: June 2007

AbstractIn this paper, we introduce a class of graphs that generalize threshold graphs by introducing threshold tolerances. Several characterizations of these graphs are presented, one of which leads to a polynomial‐time recognition algorithm. It is also shown that the complements of these graphs contain interval graphs and threshold graphs, and are contained in the subclass of chordal graphs called strongly chordal graphs, and in the class of interval tolerance graphs.
On the tree representation of chordal graphs
Authors: Shibata Yukio 
Published: June 2007

AbstractWe introduce the notion of the boundary clique and the k‐overlap clique graph and prove the following: Every incomplete chordal graph has two nonadjacent simplicial vertices lying in boundary cliques. An incomplete chordal graph G is k‐connected if and only if the k‐overlap clique graph gk(G) is connected. We give an algorithm to construct a clique tree of a connected chordal graph and characterize clique trees of connected chordal graphs using the algorithm.
On the greatest number of 2 and 3 colorings of a (v, e)‐graph
Authors: Lazebnik Felix 
Published: June 2007

AbstractLet F denote the family of simple undirected graphs on v vertices having e edges ((v, e)‐graphs) and P(λ, G) be the chromatic polynomial of a graph G. For the given integers v, e, Δ, let f(v, e, Δ) denote the greatest number of proper colorings in Δ or less colors that a (v, e)‐graph G can have, i.e., f(v, e, Δ) = max{P(Δ, G): G ∈ F}. In this paper we determine f(v, e, 2) and describe all graphs G for which P(2, G) = f(v, e, 2). For f(v, e, 3), a lower bound and an upper bound are found.
New upper bounds for the greatest number of proper colorings of a (V,E)‐graph
Authors: Lazebnik Felix 
Published: June 2007

AbstractLet 𝒻 denote the family of simple undirected graphs on v vertices having e edges ((v, e)‐graphs) and P(G; λ) be the chromatic polynomial of a graph G. For the given integers v, e, and λ, let f(v, e, λ) denote the greatest number of proper colorings in λ or less colors that a (v, e)‐graph G can have, i.e., f(v, e, λ) = max{P(G; λ): G ∈ 𝒻}. In this paper we determine some new upper bounds for f(v, e, λ).
On the decomposition of n‐cubes into isomorphic trees
Authors: Fink John Frederick 
Published: June 2007

AbstractWe prove that if T is any tree having n edges (n ≥ 1), then the n‐cube Qn can be decomposed into 2n‐1 edge‐disjoint induced subgraphs, each of which is isomorphic to T. We use this statement to obtain two results concerning decompositions of Qn into subgraphs isomorphic to members of a specified family of trees.
Neighborhood unions and hamilton cycles
Authors: Jackson Bill 
Published: June 2007

AbstractLet G be a graph on n vertices and N2(G) denote the minimum size of N(u) ∪ N(v) taken over all pairs of independent vertices u, v of G. We show that if G is 3‐connected and N2(G) ⩾ ½(n + 1), then G has a Hamilton cycle. We show further that if G is 2‐connected and N2(G) ⩾ ½(n + 3), then either G has a Hamilton cycle or else G belongs to one of three families of exceptional graphs.
The maximum number of edges in a minimal graph of diameter 2
Authors: Füredi Zoltán 
Published: June 2007

AbstractA graph g of diameter 2 is minimal if the deletion of any edge increases its diameter. Here the following conjecture of Murty and Simon is proved for n < no. If g has n vertices then it has at most n2/4 edges. The only extremum is the complete bipartite graph.
Some nordhaus‐‐ gaddum‐type results
Authors: Goddard Wayne , Henning Michael A. , Swart Henda C. 
Published: June 2007

AbstractA Nordhaus‐‐Gaddum‐type result is a (tgiht) lower or upper bound on the sum or product of a parameter of a graph and its complement. In this paper some variations are considered. First, the sums and products of ψ(G1) and ψ(G2) are examined where G1 ⊕ G2 = K(s, s), and ψ is the independence, domination, or independent domination number, inter alia. In particular, it is shown that the maximum value of the product of the domination numbers of G1 and G2 is [(s/2 + 2)2] for s ≥ 3. Thereafter it is shown that for H1 ⊕ H2 ⊕ H3 = Kp, the maximum product of the domination numbers of H2, H2, and H3 is p3/27 + Θ(p2).
Über Mehrschrittverfahren der nichtlinearen Optimierung
Authors: Richter Claus 
Published: June 2007

AbstractDie Aufgabe der nichtlinearen Optimierung wird in bekannter Weise als Variationsungleichung formuliert. Dadurch lassen sich Iterationsverfahren mit quadratischen Teilproblemen als Newton‐Verfahren zur Lösung der Ungleichung interpretieren. Eine gegenüber Schwetlick leicht modifizierte Konsistenzforderung an die in der linearisierten Variationsungleichung auftretende Matrix ermöglicht es, die Verwendung von zweiten Ableitungen zu vermeiden und die quadratische Struktur der zu lösenden Teilprobleme zu erhalten. Die Variationsungleichung mit konsistenter Approximation der Matrix wird als speziell gestörte Variationsungleichung aufgefaßt. Unter Verwendung von Resultaten, die auf Robinson und Schwetlick zurückgehen, gelingt es, lokal überlineare Konvergenz nachzuweisen. Für spezielle vorgeschlagene Realisierungen werden konkrete Abschätzungen über das Konvergenzverhalten angegeben.
On the Elastodynamic Theory of Thick Circular Plates
Authors: Celep Zekâi 
Published: June 2007

AbstractConsidering elastodynamic deformation of circular plates, this paper presents a generalization of the method of initial functions in cylindrical coordinates. The governing equations of the theory are derived from the three dimensional elastodynamic equations. The method is applied to the free vibration of the clamped circular plate. Numerical results are obtained and displayed in figures. They are compared with the foregoing results. Besides, the variations of the characteristic quantities of the plate are given along the plate thickness.