bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metallodynamers: Neutral Double‐Dynamic Metallosupramolecular Polymers
Authors: Chow Cheuk‐Fai , Fujii Shunsuke , Lehn Jean‐Marie 
Published: August 2008

AbstractNine neutral dynamic metallosupramolecular polymers (metallodynamers) based on acyl hydrazone derived metal coordination centers (Co2+, Ni2+, Zn2+, and Cd2+) were generated through self‐assembly polymerization. These are linear coordination polymers with specific optical and mechanical properties. Monomer selection was found to take place in a mixture of subcomponents (carboxyaldehydes and bisacyl hydrazides) driven by hexacoordination to a specific metal ion. Most importantly, the metallodynamers were found to modify their constitution by exchanging and reshuffling their components with another metallodynamer through ligand exchange at the metal coordination site in solution as well as in the neat phase. As a result, the materials undergo remarkable changes in both their mechanical and optical properties.
Solvent‐Induced Aggregation and Cation‐Controlled Self‐Assembly of Tripodal Squaraine Dyes: Optical, Chiroptical and Morphological Properties
Authors: Chithra Parayalil , Varghese Reji , Divya Kizhmuri P. , Ajayaghosh Ayyappanpillai 
Published: August 2008

AbstractThe synthesis, characterisation, optical, chiroptical, aggregation, and alkaline earth metal cation assisted self‐assembly properties of tripodal squaraine dyes have been described. In the tripodal geometry, these dyes exhibit three absorption bands around 650, 620 and 580 nm in contrast to the single, sharp absorption of a simple dye (SQ) at 640 nm. The fluorescence quantum yield of the squaraine dyes are 25–30 times lower when compared to that of SQ, which indicates intramolecular exciton interaction as a result of the confinement of the dyes. The evaporation of an acetonitrile solution of the dye resulted in the formation of vesicular objects as confirmed by AFM and TEM analyses. However, evaporation of an acetonitrile solution containing 10–12 % water gave short fibrous aggregates. In the presence of Ca2+ or Mg2+ ions, the dyes exhibit an intense and sharp absorption band at 547 nm with a concomitant decrease of the native absorption. Interestingly, the dye with chiral groups failed to give a circular dichroic signal during aggregation in solvent mixtures, whereas strong signals were observed in the presence of Ca2+ and Mg2+ ions. AFM and TEM analyses of the corresponding cation complexes revealed the formation of worm like nanohelices. However, addition of EDTA to the Ca2+ or Mg2+ complex exhibited a reversal of the absorption, emission, and circular dichroic spectra to that of the native dye, indicating decomplexation. AFM analyses revealed the transformation of the helices to particles. These observations reveal the difference in the nature and properties of the simple aggregates formed in solvent mixtures and those formed in the presence of cations. In the present study, we were able to establish the importance of specific cation binding in controlling the size, shape, and properties of the hierarchical assemblies of tripodal squaraines.
A Non‐Cross‐Linked Soluble Polystyrene‐Supported Ruthenium Catalyst for Carbenoid Transfer Reactions
Authors: Choi Matthew Kwok‐Wai , Yu Wing‐Yiu , So Man‐Ho , Zhou Cong‐Ying , Deng Qing‐Hai , Che Chi‐Ming 
Published: August 2008

AbstractRuthenium nanoparticles supported on non‐cross‐linked soluble polystyrene were prepared by reacting [RuCl2(C6H5CO2Et)]2 with polystyrene in open air. They effectively catalyze intra‐ and intermolecular carbenoid insertion into CH and NH bonds, alkene cyclopropanation, and ammonium ylide/[2,3]‐sigmatropic rearrangement reactions. This supported ruthenium catalyst is much more reactive than [RuCl2(p‐cymene)]2 and [Ru(Por)CO] for catalytic intermolecular carbenoid CH bond insertion into saturated alkanes. By using α‐diazoacetamide as a substrate for intramolecular carbenoid CH insertion, the supported ruthenium catalyst can be recovered and reused for ten successive iterations without significant loss of activity.
Synthesis of Diamino Carboxylic Esters by Palladium‐Catalyzed Oxidative Intramolecular Diamination of Acrylates
Authors: Muñiz Kilian , Streuff Jan , Chávez Patricia , Hövelmann Claas H. 
Published: August 2008

AbstractUnligated palladium(II) salts catalyze the oxidative diamination of acrylic esters to yield 2,3‐diamino carboxylic esters. The reaction employs copper(II) bromide as oxidant and proceeds with good to excellent stereoselectivities and complete chemoselectivity. Preliminary mechanistic studies provide evidence for the involvement of a direct amination of the CPd bond in the α position relative to the ester group. This protocol significantly broadens the overall scope of the palladium‐catalyzed diamination of alkenes and represents the first direct diamination of functionalized nonterminal substrates. The reaction yields readily protected 2,3‐diamino acid derivatives, which can be considered as highly functionalized building blocks for subsequent synthesis. The use of one of these new diamination products as a suitable starting material in a short synthesis of the alkaloid absouline is demonstrated as an example.
On the late twentieth century decrease in Australian east coast rainfall extremes
Authors: Speer Milton S. 
Published: August 2008

AbstractA change from negative to positive circulation anomalies over New South Wales (NSW) during the 1970s resulted in a decrease in east coastal low‐pressure systems and accompanying rain. Negative pressure anomalies over eastern Australia, anomalous onshore low‐level winds and larger NSW rainfall totals since 1950, occur in the cool phase of the IPO rather than the warm phase (post‐1976). Larger NSW extreme annual rainfall totals occurred prior to 1977 and were characterized by negative mean sea level pressure (MSLP) anomalies over eastern Australia. In contrast, extreme annual rainfall totals from 1977 were smaller and characterized by positive MSLP anomalies. Copyright © 2008 Royal Meteorological Society
Quantile regression for binary performance indicators
Authors: Hewson Paul , Yu Keming 
Published: August 2008

AbstractQuantile regression is an emerging modelling technique; we examine an approach allowing this technique to model binomial variables in a Bayesian framework and illustrate the value of this advanced technique on a set of local government performance indicators from England and Wales. In U.K. local government, there is currently particular interest in assessing performance relative to ‘top’ and ‘bottom’ quartiles; all authorities are expected to match the current best quartile performance within 5 years, any authority in the ‘bottom’ quartile is assumed to be significantly below par. By its very nature, quantile regression lets us to explore relationships between various covariates and these particular levels of performance. Additionally, by examining a number of other percentiles, we demonstrate how quantile regression gives a much fuller insight into the apparent behaviour of the system we are modelling. Rather than relying on asymptotic results, we use Bayesian methods that allow us to explore the uncertainty implicit in our model building and predictions. We suggest that this is most important when analysing data that are used to make managerial and administrative decisions. Copyright © 2008 John Wiley & Sons, Ltd.
Feuchtetransport in 15 cm dicken, liegend hergestellten wasserundurchlässigen Fertigteilen aus Stahlbeton bei drückendem Wasser
Authors: Mähner Dietmar , Becker Markus 
Published: August 2008

AbstractIn Versuchen konnte das Arbeitsmodell des Deutschen Ausschusses für Stahlbeton für Feuchtebedingungen in einem Betonbauteil unter einseitiger Beaufschlagung mit drückendem Wasser auf 15 cm dicke Betonfertigteilwände, die liegend hergestellt wurden, erweitert werden. Bei Wanddicken von 15 cm wurde trotz unterschiedlichen Beaufschlagungen mit drückendem Wasser über einen Zeitraum von einem Jahr kein signifikant unterschiedlicher Feuchtedurchtritt (weder qualitativ noch quantitativ) festgestellt. Der geringe Wasserzementwert der Fertigteile sowie die liegende Herstellung und Verdichtung lassen vermuten, dass in den Versuchen nur eine Feuchteabgabe aufgrund von Diffusion des anfänglich vorhandenen Überschusswassers festgestellt wurde.
Querbeanspruchung von Ankergruppen in Randnähe – Stochastische Studien
Authors: Spyridis Panagiotis , Unterweger Andreas , Mihala Ronald , Bergmeister Konrad 
Published: August 2008

AbstractAnkergruppen in Beton kommen als Befestigungsmittel häufig in Randnähe zur Anwendung. Bei der Verbindung der Stahlanker mit einer Montageplatte kommt es aufgrund von Montagetoleranzen zu einer zufälligen Ankerstellung in den Durchgangslöchern der Montageplatte. Dadurch werden bei einer Querbeanspruchung der Gruppenbefestigung nicht alle Anker gleichzeitig aktiviert, was die Tragfähigkeit dieser in Randnähe besonders beeinflusst. Durch genauere Untersuchung dieses Sachverhalts sollten verbesserte Bemessungskonzepte entwickelt werden.Im vorliegenden Beitrag wird auf eine stochastische Analyse eingegangen, welche durch zufällige Ankeranordnungen, verschiedene Geometrien und mechanische Parameter die gegenseitige Beeinflussung benachbarter Anker untersucht. Aufgrund dieser Untersuchungen wird im Abschluss eine Gleichung vorgeschlagen, welche den Zusammenhang zwischen Geometrie, Montagetoleranzen und der Bruchlast der Gruppenbefestigung unter Querlast beschreibt.
Ligand‐pKa Shifts through Metals: Potential Relevance to Ribozyme Chemistry
Authors: Lippert Bernhard 
Published: August 2008

AbstractFunctional and crystallographic analyses of catalytically active RNA molecules (‘ribozymes’) have revealed a multitude of different routes by which nature accomplishes cleavage reactions of the RNA sugar‐phosphate backbone. While there is agreement that these reactions involve general acid–base chemistry, the choice of ‘acid’ and of ‘base’ appears to be quite versatile. Among the numerous surprises that have emerged from these studies in recent years is the phenomenon of ‘shifted pKa values’ of nucleobases, hence, the fact that pKa values of isolated nucleobases in H2O can be shifted in either direction – upward or downward – into the physiological pH range, and that consequently allows these nucleobases to function as ‘acids’ or ‘bases’. Another change in paradigm in recent years relates to the role of divalent metal ions in these catalytic reactions, which points to the possibility of an indirect involvement in the catalytic cycle rather than necessarily to a direct participation, as in the case with the hepatitis delta virus ribozyme. In this review, basic features of nucleobases and/or aqua ligand pKa shifts caused by metal coordination and H‐bonding are discussed.
Characterization of Metal‐Responsive Transcription Factor (MTF‐1) from the Giant Rodent Capybara Reveals Features in Common with Human as Well as with Small Rodents (Mouse, Rat). Short Communication
Authors: Lindert Uschi , Leuzinger Lucas , Steiner Kurt , Georgiev Oleg , Schaffner Walter 
Published: August 2008

AbstractFrom mammals to insects, metal‐responsive transcription factor 1 (MTF‐1) is essential for the activation of metallothionein genes upon heavy‐metal load. We have previously found that human MTF‐1 induces a stronger metal response than mouse MTF‐1. The latter differs from the human one in a number of amino acid positions and is also shorter by 78 aa at its C‐terminus. We reasoned that the weaker metal inducibility might be associated with a lesser demand for tight metal homeostasis in a low‐weight, short‐lived animal, and thus set out to determine the sequence of MTF‐1 from the largest living rodent, the Brazilian capybara that can reach 65 kg and also has a considerably longer life span than smaller rodents. An expression clone for capybara MTF‐1 was then tested for its activity in both mouse and human cells. Our analysis revealed three unexpected features: i) capybara MTF‐1 in terms of amino acid sequence is much more closely related to human than to mouse MTF‐1, suggesting an accelerated evolution of MTF‐1 in the evolutionary branch leading to small rodents; ii) capybara MTF‐1 is even 32 aa shorter at its C‐terminus than mouse MTF‐1, and iii) in an activity test, it is not more active than mouse MTF‐1. The latter two findings might indicate that capybara has evolved in an environment with low heavy‐metal load.
The Influence of Auranofin, a Clinically Established Antiarthritic Gold Drug, on Bone Metabolism: Analysis of Its Effects on Human Multipotent Adipose‐Derived Stem Cells, Taken as a Model
Authors: Chiellini Chiara , Casini Angela , Cochet Olivia , Gabbiani Chiara , Ailhaud Gérard , Dani Christian , Messori Luigi , Amri Ez‐Zoubir 
Published: August 2008

AbstractAuranofin is a gold‐based antiarthritic drug in clinical use for more that 25 years. However, in spite of a long established use, its specific effects on bone metabolism are still greatly controversial. We have analyzed in vitro the actions of auranofin on human multipotent adipose‐derived stem (hMADS) cells, used as a model for bone metabolism, since these cells were reported to undergo osteogenesis both in vitro and in vivo. Cytotoxicity of auranofin on hMADS cells, differentiated into osteoblasts, was initially assessed. Thereafter, the consequences of exposure to nontoxic but clinically relevant auranofin concentrations were analyzed by monitoring the seleno‐protein glutathione peroxidase 3 or alkaline phosphatase, a characteristic biomarker of osteogenesis. Notably, we found that chronic treatment with auranofin alters only weakly the levels of alkaline phosphatase, thus implying an overall modest effect on osteogenesis. In contrast, auranofin turned out to greatly affect glutathione peroxidase 3 activity. The possible medical implications of these findings are discussed.
Influence of Carbonate on the Binding of Carboplatin to DNA
Authors: Sorokanich Robert S. , Di Pasqua Anthony J. , Geier Martina , Dabrowiak James C. 
Published: August 2008

AbstractThe reaction of aged carboplatin (reaction of carboplatin in 24 mM NaHCO3 for 45 h, 37°, pH 8.6) with pBR322 DNA at 0<r<2.8, where r=[drug]/[DNA‐bp], in 24 mM HEPES buffer, pH 7.4, for 24 h, followed by agarose gel electrophoresis showed DNA mobility changes consistent with unwinding closed circular DNA. However, identical experiments conducted in a two‐buffer system, 24 mM HEPES plus 24 mM carbonate, showed no DNA mobility changes, indicating that carbonate blocks formation of the 1,2 intrastrand cross‐link on DNA. Studies with aged carboplatin and with cisplatin carried out with ca. 4.0<r<10.0 in the two‐buffer system show that some DNA binding and unwinding occurs for both drugs. Since carbonate inhibits the binding of aged carboplatin and cisplatin to DNA, carbonate present in the body likely modulates the reactivity of these drugs with a variety of biological targets including DNA.
Effects of Vanadium‐Containing Compounds on Membrane Lipids and on Microdomains Used in Receptor‐Mediated Signaling
Authors: Roess Deborah A. , Smith Steven M. L. , Winter Peter , Zhou Jun , Dou Ping , Baruah Bharat , Trujillo Alejandro M. , Levinger Nancy E. , Yang Xioda , Barisas B. George , Crans Debbie C. 
Published: August 2008

AbstractThere is increasing evidence for the involvement of plasma membrane microdomains in insulin receptor function. Moreover, disruption of these structures, which are typically enriched in sphingomyelin and cholesterol, results in insulin resistance. Treatment strategies for insulin resistance include the use of vanadium (V) compounds which have been shown in animal models to enhance insulin responsiveness. One possible mechanism for insulin‐enhancing effects might involve direct effects of V compounds on membrane lipid organization. These changes in lipid organization promote the partitioning of insulin receptors and other receptors into membrane microdomains where receptors are optimally functional. To explore this possibility, we have used several strategies involving V complexes such as [VO2(dipic)]− (pyridin‐2,6‐dicarboxylatodioxovanadium(V)), decavanadate (V10O, V10), BMOV (bis(maltolato)oxovanadium(IV)), and [VO(saltris)]2 (2‐salicylideniminato‐2‐(hydroxymethyl)‐1,3‐dihydroxypropane‐oxovanadium(V)). Our strategies include an evaluation of interactions between V‐containing compounds and model lipid systems, an evaluation of the effects of V compounds on lipid fluidity in erythrocyte membranes, and studies of the effects of V‐containing compounds on signaling events initiated by receptors known to use membrane microdomains as signaling platforms.
Formation of {Cu(μ‐O)2}2+ Core Due to Dioxygen Reactivity of a Copper(I) Complex Supported by a New Hybrid Tridentate Ligand: Reaction with Exogenous Substrates
Authors: Mandal Sukanta , De Anindita , Mukherjee Rabindranath 
Published: August 2008

AbstractReaction of a CuI complex of a hybrid tridentate ligand, encompassing [2‐(pyridin‐2‐yl)ethyl]amine and dimethyl‐substituted ethylalkylamine with dioxygen, generates in acetone at −80° putative bis(μ‐oxo)dicopper(III) intermediate. Structural characterization of a PPh3‐adduct of a mononuclear CuI complex of this new ligand has been achieved. This ligand coordinates in a facial mode utilizing three N‐atoms (CH2CH2Py, CH2CH2NMe2, and NCH2Ph). Reactivity of bis(μ‐oxo)dicopper(III) intermediate toward exogenous substrates (2,4‐di(tert‐butyl)phenol and 2,4,6‐tri(tert‐butyl)phenol) has also been investigated.
Interaction of Flavin Adenine Dinucleotide (FAD) with a Glassy Carbon Electrode Surface
Authors: Wei Haizhen , Omanovic Sasha 
Published: August 2008

AbstractThe interaction of flavin adenine dinucleotide (FAD) with a glassy carbon electrode (GCE) surface was investigated in terms of the FAD adsorption thermodynamics and kinetics, the subsequent electroreduction mechanism, and the corresponding electron‐transfer rate. The kinetics of FAD electroreduction at the GCE was found to be an adsorption‐controlled process. A set of electroreduction kinetic parameters was calculated: the true number of electrons involved in the FAD reduction, n=1.76, the apparent transfer coefficient, αapp=0.41, and the apparent heterogeneous electron‐transfer rate constant, kapp=1.4 s−1. The deviation of the number of exchanged electrons from the theoretical value for the complete reduction of FAD to FADH2 (n=2) indicates that a small portion of FAD goes to a semiquinone state during the redox process. The FAD adsorption was well described by the Langmuir adsorption isotherm. The large negative apparent Gibbs energy of adsorption (ΔGads=−39.7 ±0.4 kJmol−1) indicated a highly spontaneous and strong adsorption of FAD on the GCE. The energetics of the adsorption process was found to be independent of the electrode surface charge in the electrochemical double‐layer region. The kinetics of FAD adsorption was modeled using a pseudo‐first‐order kinetic model.
Liposomal Forms of Rhenium Cluster Compounds: Enhancement of Biological Activity
Authors: Shtemenko Natalia I. , Zabitskaya Elena D. , Berzenina Oksana V. , Yegorova Dina E. , Shtemenko Alexander V. 
Published: August 2008

AbstractLiposomal formulations of dinuclear cluster rhenium (Re) compounds were used in biochemical trials. Interaction of liposomal forms of some Re compounds with red blood cells in experiments in vitro showed strong cell‐stabilizing properties. In the models of tumor growth and hemolytic anemia in vivo, liposomal forms had better therapeutic effects in comparison with their solutions. The process of formation of liposomes of cluster Re compounds with different organic ligands was investigated by the method of electronic absorption spectra and mechanism of their interactions with lipids is proposed. Encapsulation of cluster Re compounds to lipid coating may have activation significance for the quadruple ReRe bond.
Cytochrome P450 2J2*7 polymorphisms in Japanese, Mongolians and Ovambos
Authors: Takeshita Haruo , Tsubota Etsuko , Takatsuka Hisakazu , Kunito Takashi , Fujihara Junko 
Published: August 2008

AbstractHuman cytochrome P450 2J2 (CYP2J2) is abundant in cardiovascular tissue and active in the metabolism of arachidonic acid to eicosanoids that have potent vasodilatory properties. Variability of the CYP2J2 gene is highly constrained except for its proximal promoter: there is a relatively common and functionally relevant single nucleotide polymorphism, indicated by −50G > T polymorphism (CYP2J2*7). Although genetic variation is known among ethnic groups, data for allele frequency are limited to a few Caucasian, Asian, and one African populations. In the present study, genotype distribution of CYP2J2*7 polymorphisms was investigated using polymerase chain reaction and restriction fragment length polymorphism assay in Japanese (n = 338), Mongolian (n = 118), and Ovambo (n = 186) populations and the findings compared with other populations. The mutant (CYP2J2*7) frequencies in the Japanese, Mongolians, and Ovambos were 0.0621, 0.0339, and 0.0672, respectively. Except for the Taiwanese, a general uniformity in the polymorphism in the Asian populations was observed. The mutation frequency of Ovambos was relatively lower than that of the African‐American population. This study is the first to investigate the distribution of the CYP2J2*7 gene polymorphisms in Japanese, Mongolians, and Ovambos. These data will be informative and facilitate genetic association studies, in Asian and African populations for CYP2J2‐related diseases such as cardiovascular disorders. Copyright © 2008 John Wiley & Sons, Ltd.
Metal‐Free and PdII‐Promoted [2+3] Cycloadditions of a Cyclic Nitrone to Phthalonitriles: Syntheses of Oxadiazolines as well as Phthalamide–PdII and Dihydropyrrolyl‐iminoisoindolinone–PdII Complexes with High Catalytic Activity in Suzuki–Miyaura Cross‐Coupling Reactions
Authors: Lasri Jamal , Kopylovich Maximilian N. , Guedes da Silva M. Fátima C. , Charmier M. Adília Januário , Pombeiro Armando J. L. 
Published: August 2008

AbstractThe previously unknown reactions between phthalonitriles, 1,2‐(CN)2(C6)R1R2R3R4 1 (1 a, R1=R2=R3=R4=H; 1 b, R1=R2=R4=H, R3=CH3; 1 c, R1=R4=H, R2=R3=Cl; 1 d, R1=R2=R3=R4=Cl; 1 e, R1=R2=R3=R4=F), and a cyclic nitrone, −O+NCHCH2CH2CMe2 2, proceed under heating in a sealed tube to give phthalimides 3, 2‐oxadiazolyl‐benzonitriles 4 or ortho‐bis(oxadiazolyl)tetrafluorobenzene 4 e′. In the presence of palladium(II) chloride, phthalonitriles 1 react with 2 at room temperature, to give bis(pyrrolidin‐2‐ylidene)phthalamide PdII complexes 5 via metal‐promoted rupture of the NO bond of the oxadiazoline ring. The ketoimine ligands thus generated can be liberated from the metal by displacement with a diphosphine. Although the first [2+3] cycloaddition of 2 to 1 can occur in the absence of the metal to give the mono‐cycloadducts 4, the second [2+3] coupling at the still‐unreacted cyano group requires its activation by coordination to PdII, affording complexes 6 containing two ligated oxadiazolyl‐benzonitriles. These ligands undergo either i) further cycloaddition with 2 to afford ultimately (upon rearrangement) the bis(pyrrolidinylidene)phthalamide complexes 5 or ii) NO bond cleavage in the oxadiazoline ring with intramolecular attack of the imine nitrogen on the cyano carbon and bridging to a second PdII center to afford dimeric palladium(II) complexes 7, with chloride bridges, that bear a dihydropyrrolyl‐iminoisoindolinone, a new type of ligand.The compounds were characterized by IR, 1H, and 13C NMR spectroscopy, ESI MS or FAB+ MS, elemental analyses and, in the case of 4 c, 5 a, 5 c, and 7 c, also by X‐ray diffraction analysis. Complexes 5 a and 7 c show high catalytic activity for the Suzuki–Miyaura cross‐coupling reaction of bromobenzene and phenylboronic acid and give biphenyl in high yields with turnover frequencies (TOFs) of up to 9.0×105 h−1.