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Selected AbstractsComplexation of 2,6-Bis(3-pyrazolyl)pyridine,Bis(thiocyanato)iron(II) with a Bridging 4,4,-Bipyridine: A New Example of a Dinuclear Spin Crossover ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2008Dalila Fedaoui Abstract Investigation of the coordination behavior of 2,6-bis(3-pyrazolyl)pyridine,bis(thiocyanato)iron(II) towards bridging ligands led to the discovery of a novel dinuclear complex showing spin-crossover. Chemical and structural characterization and a first report of physical properties are presented.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] ChemInform Abstract: New Examples of Ternary Rare-Earth Metal Boride Carbides Containing Finite Boron,Carbon Chains: The Crystal and Electronic Structure of RE15B6C20 (RE: Pr, Nd).CHEMINFORM, Issue 47 2008Volodymyr Babizhetskyy Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Two New Examples of very Short Thallium,Transition Metal Contacts: Tl3Ag3Sb2S6 and Tl3Ag3As2S6.CHEMINFORM, Issue 34 2008Ljiljana Karanovic Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Syntheses and Crystal Structures of [Mg(HF)2](SbF6)2 and [Ca(HF)2](SbF6)2: New Examples of HF Acting as a Ligand to Metal Centers.CHEMINFORM, Issue 32 2003Alenka Turicnik Abstract For Abstract see ChemInform Abstract in Full Text. [source] New role for majors in Atta leafcutter antsECOLOGICAL ENTOMOLOGY, Issue 5 2007SOPHIE E. F. EVISON Abstract 1.,Atta (Hymenoptera: Formicidae) leafcutter ants display the most polymorphic worker caste system in ants, with different sizes specialising in different tasks. The largest workers (majors) have large, powerful mandibles and are mainly associated with colony defence. 2.,Majors were observed cutting fallen fruit and this phenomenon was investigated in the field by placing mango fruit near natural Atta laevigata and Atta sexdens colonies in São Paulo State, Brazil. 3.,Ants cutting the fruit were significantly heavier (mean = 49.1 mg, SD = 11.1 mg, n= 90) than the ants carrying the fruit back to the nest (mean = 20.9 mg, SD = 9.2 mg, n= 90). 4.,Fruit pieces cut by majors were small (mean = 15.9 mg), approximately half the weight of leaf pieces (mean = 28.5 mg) cut and carried by media foragers. It is hypothesised that it is more difficult to cut large pieces from three-dimensional objects, like fruit, compared to two-dimensional objects, like leaves, and that majors, with their longer mandibles, can cut fruit into larger pieces than medias. 5.,The study shows both a new role for Atta majors in foraging and a new example of task partitioning in the organisation of foraging. [source] Lost zooplanktivorous cichlid from Lake Victoria reappears with a new tradeECOLOGY OF FRESHWATER FISH, Issue 4 2003E. F. B. Katunzi Abstract,,, The zooplanktivorous cichlid Haplochromis pyrrhocephalus, which was one of the most common haplochromine species in the Mwanza Gulf of Lake Victoria, had almost completely disappeared after the Nile perch upsurge in the 1980s. In the second half of the 1990s, this species suddenly reappeared in the strongly changed ecosystem. Gut content investigation revealed a change in diet. Currently, H. pyrrhocephalus eats large prey more frequently than in the past. These large prey comprise fish, shrimps and molluscs. The latter two were never encountered in specimens from the past. Particularly feeding on molluscs was unexpected, as it had been suggested that, because of anatomical constraints, molluscivory and zooplanktivory are incompatible in cichlid fish. Our observations provide a new example of the extreme versatility in feeding behaviour in haplochromine cichlids. [source] REPRESSION OF COMPETITION AND THE EVOLUTION OF COOPERATIONEVOLUTION, Issue 4 2003Steven A. Frank Abstract Repression of competition within groups joins kin selection as the second major force in the history of life shaping the evolution of cooperation. When opportunities for competition against neighbors are limited within groups, individuals can increase their own success only by enhancing the efficiency and productivity of their group. Thus, characters that repress competition within groups promote cooperation and enhance group success. Leigh first expressed this idea in the context of fair meiosis, in which each chromosome has an equal chance of transmission via gametes. Randomized success means that each part of the genome can increase its own success only by enhancing the total number of progeny and thus increasing the success of the group. Alexander used this insight about repression of competition in fair meiosis to develop his theories for the evolution of human sociality. Alexander argued that human social structures spread when they repress competition within groups and promote successful group-against-group competition. Buss introduced a new example with his suggestion that metazoan success depended on repression of competition between cellular lineages. Maynard Smith synthesized different lines of thought on repression of competition. In this paper, I develop simple mathematical models to illustrate the main processes by which repression of competition evolves. With the concepts made clear, I then explain the history of the idea. I finish by summarizing many new developments in this subject and the most promising lines for future study. [source] Rapid estimation of chemical kinetics by implicit calibration.JOURNAL OF CHEMOMETRICS, Issue 2 2003Abstract This study continues the development of a method, implicit calibration, for estimating kinetic parameters from on-line measurements of batch reactions. The basic idea of implicit calibration is to combine non-linear parameter estimation with the calibration of measured spectra with concentrations calculated by an assumed kinetic model. A new example is studied, an esterification reaction with a rather complicated kinetic mechanism, where activities, instead of concentrations, and NIR spectra are used as measurements. The emphasis in the study is on estimating the uncertainty of the kinetic parameters. Two approaches, linearization and bootstrap, are applied. In the case studied, the two approaches give closely similar estimates of the uncertainty. As well, a new way is introduced to control the rigidity of the implicit calibration, based on minimizing the lack of fit of the model. It is also shown that ,mixed implicit calibration', i.e. implicit calibration combined with a few off-line calibrated concentrations, greatly enhances the identifiability of the kinetic model. Copyright © 2003 John Wiley & Sons, Ltd. [source] Synthesis of 2,4-difuryl-4H -3,1-benzothiazines via a furan ring migration reactionJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2008Vladimir T. Abaev A new simple synthetic approach to 2,4-difuryl-4H -3,1-benzothiazines from 2-isothiocyanoaryldifuryl-methanes in the presence of acidic catalyst is described. This rearrangement is a new example of furan ring migration reaction resulting from intramolecular attack with electrophilic carbon. [source] 5-Oxatricyclo[5.1.0.01,3]octan-4-one, containing an enantiomorph and a racemate and not two polymorphs, is another example of a composite crystalACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2003Frank H. Herbstein This new example of a composite crystal adds to the small number previously reported among inorganic and molecular materials. Revision of the nomenclature used allows more fruitful comparison with the precedents. [source] K2[O(HgSO3)3], a new sulfitomercurate with an [OHg3] coreACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2008Matthias Weil The structure of dipotassium ,3 -oxido-tris[sulfitomercurate(II)], K2[O(HgSO3)3], is characterized by segregation of the K+ cations and complex [O(HgSO3)3]2, anions into layers parallel to (010). The anion has m symmetry and is a new example of a ,3 -oxido-trimercurate complex with a central [OHg3] core. This unit adopts the shape of a flat, almost trigonal, pyramid (mean O,Hg = 2.072,Å and mean Hg,O,Hg = 110.8°). The two independent Hg,S bonds have nearly the same length (mean Hg,S = 2.335,Å). Due to intermolecular O...Hg donor,acceptor interactions greater than 2.65,Å, the O,Hg,S fragments are slightly bent. The [KO9] coordination polyhedron of the K+ cation approaches a distorted tricapped trigonal prism with a [6+1+2] coordination. [source] Antituberculosis Agents and an Inhibitor of the para -Aminobenzoic Acid Biosynthetic Pathway from Hydnocarpus anthelminthica SeedsCHEMISTRY & BIODIVERSITY, Issue 8 2010Jun-Feng Wang Abstract Investigation on the extracts of Hydnocarpus anthelminthica seeds led to the isolation of three new compounds, anthelminthicins A,C (1,3, resp.), and two known ones, namely chaulmoogric acid (4) and ethyl chaulmoograte (5). Their structures were determined mainly by using spectroscopic techniques. The absolute configuration at the cyclopentenyl moiety of compound 2 was rationalized by quantum calculations. Base hydrolysis, followed by optical-rotation comparison, allowed assignment of the configuration of chaulmoogric-acid moiety of compounds 3 and 5. Biological assays revealed that compounds 1,5 significantly inhibit Mycobacterium tuberculosis (MTB) growth with MIC values of 5.54, 16.70, 4.38, 9.82, and 16.80,,M, respectively. Compound 3 was found to inhibit the pathway between chorismate and para -aminobenzoic acid (pAba) with a MIC value of 11.3,,M, representing a new example of pAba inhibitor isolated from a natural source. All compounds were not toxic to Candida albicans SC5314 at a concentration up to 100,,M. [source] EPR Insensitivity of the Metal-Nitrosyl Spin-Bearing Moiety in Complexes [LnRuII -NO·]kEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2004Stéphanie Frantz Abstract A survey of 18 paramagnetic species [LnRu(NO)]k, including seven new examples studied by in situ electrolysis, reveals a surprisingly narrow range of EPR parameters despite a wide variety of ligands such as pyridine, polypyridines, imines, amines, nitriles, phosphanes, carbonyl, cyclopentadienides, halides, hydride, hydroxide, thiocyanate or cyanide: g1 = 2.015 ± 0.02, g2 = 1.990 ± 0.015, g3 = 1.892 ± 0.03, gav = 1.968 ± 0.02, ,g = g1 , g3 = 0.122 ± 0.037, A2(14N) = 3.3 ± 0.5 mT. This rather small variability, smaller still if the organometallic compounds are excluded, differs from the wider range of EPR data reported for nitrosyliron species with S = 1/2; apparently, the {RuNO}7 configuration involves a rather invariant and relatively covalent metal,NO interaction. DFT calculations were employed for [(NC)5Ru(NO)]3, to reproduce the EPR data, to evaluate the spin distribution (58% spin density on NO), and to reveal structural changes on reduction such as the Ru,N,O bending and Ru,NO bond lengthening. In addition, the possibility of staggered and eclipsed conformations is discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] The Intramolecular Aromatic Electrophilic Substitution of Aminocyclopropanes Prepared by the Kulinkovich,de Meijere Reaction,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2005Laurent Larquetoux Abstract This article describes new examples of intramolecular Kulinkovich,de Meijere reactions applied to carboxylic amides bearing an olefin moiety and an aromatic ring at a suitable position. Upon heating, the aminocyclopropanes thus obtained undergo intramolecular aromatic electrophilic substitution to afford polycyclic systems. Among the various starting materials prepared, best results are obtained from indole and phenol derivatives. In each case, a benzylic quaternary centre is introduced at the newly-formed ring junction. On one example, the efficiency of the cyclisation has been dramatically improved using a catalytic amount of para -toluenesulfonic acid. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Embedding a Gaussian discrete-time autoregressive moving average process in a Gaussian continuous-time autoregressive moving average processJOURNAL OF TIME SERIES ANALYSIS, Issue 4 2007Mituaki Huzii Abstract., Embedding a discrete-time autoregressive moving average (DARMA) process in a continuous-time ARMA (CARMA) process has been discussed by many authors. These authors have considered the relationship between the autocovariance structures of continuous-time and related discrete-time processes. In this article, we treat the problem from a slightly different point of view. We define embedding in a more rigid way by taking account of the probability structure. We consider Gaussian processes. First we summarize the necessary and sufficient condition for a DARMA process to be able to be embedded in a CARMA process. Secondly, we show a concrete condition such that a DARMA process can be embeddable in a CARMA process. This condition is new and general. Thirdly, we show some special cases including new examples. We show how we can examine embeddability for these special cases. [source] Maslovian Lagrangian surfaces of constant curvature in complex projective or complex hyperbolic planesMATHEMATISCHE NACHRICHTEN, Issue 11 2005Bang-Yen Chen Abstract A Lagrangian submanifold is called Maslovian if its mean curvature vector H is nowhere zero and its Maslov vector field JH is a principal direction of AH . In this article we classify Maslovian Lagrangian surfaces of constant curvature in complex projective plane CP2 as well as in complex hyperbolic plane CH2. We prove that there exist 14 families of Maslovian Lagrangian surfaces of constant curvature in CP2 and 41 families in CH2. All of the Lagrangian surfaces of constant curvature obtained from these families admit a unit length Killing vector field whose integral curves are geodesics of the Lagrangian surfaces. Conversely, locally (in a neighborhood of each point belonging to an open dense subset) every Maslovian Lagrangian surface of constant curvature in CP2 or in CH2 is a surface obtained from these 55 families. As an immediate by-product, we provide new methods to construct explicitly many new examples of Lagrangian surfaces of constant curvature in complex projective and complex hyperbolic planes which admit a unit length Killing vector field. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] An unbiased pilot survey for Galactic water masersMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2010J. L. Caswell ABSTRACT The Australia Telescope Compact Array has been used in a fast surveying mode to study the 22-GHz transition of water in two small sample regions of the southern Galactic plane. The observations allow an unbiased search for water masers, including any that may have no association with masers from other molecules (or indeed, no association with any other detectable celestial object). Positions with arcsecond accuracy were obtained from the original survey data for detected sources, and these were re-observed at an epoch more than two years later. Variability of the spectra between the epochs was considerable: our total of 32 masers comprises 24 detected at both epochs, two detected at only the first epoch and six detected at only the follow-up epoch. The success of our surveying mode shows it to be a practical strategy for the difficult task of extending unbiased water maser surveys to a large portion of the Galactic plane. Our results show quantitatively the effect of variability on the completeness of surveys conducted at a single epoch. Most of our maser detections are new discoveries. Only four had previously been detected (in searches towards interesting targets in the survey area). The high density of water masers from our unbiased survey supports earlier suggestions that they are the most populous maser species, and one of the most sensitive and reliable tracers of massive young stellar objects , newly forming massive young stars. The spectra of nine masers show high-velocity emission, and they show a striking preponderance of blueshifted high-velocity features. This is compatible with such blueshifts being a characteristic of populations dominated by masers at the earliest evolutionary stage of star formation, in some cases prior to the onset of methanol masers. Amongst the high-velocity emission sources there are two new examples where blueshifted high-velocity outflows dominate the total emission; these substantially increase the previously known meagre population of five such objects and suggest that they may be surprisingly abundant. [source] Uncountable graphs and invariant measures on the set of universal countable graphsRANDOM STRUCTURES AND ALGORITHMS, Issue 3 2010Fedor Petrov Abstract We give new examples and describe the complete lists of all measures on the set of countable homogeneous universal graphs and Ks -free homogeneous universal graphs (for s , 3) that are invariant with respect to the group of all permutations of the vertices. Such measures can be regarded as random graphs (respectively, random Ks -free graphs). The well-known example of Erdös,Rényi (ER) of the random graph corresponds to the Bernoulli measure on the set of adjacency matrices. For the case of the universal Ks -free graphs there were no previously known examples of the invariant measures on the space of such graphs. The main idea of our construction is based on the new notions of measurable universal, and topologically universal graphs, which are interesting themselves. The realization of the construction can be regarded as two-step randomization for universal measurable graph : "randomization in vertices" and "randomization in edges." For Ks -free, s , 3, there is only randomization in vertices of the measurable graphs. The completeness of our lists is proved using the important theorem by Aldous about S, -invariant matrices, which we reformulate in appropriate way. © 2010 Wiley Periodicals, Inc. Random Struct. Alg., 2010 [source] Characterization of silsesquioxanes by size-exclusion chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 4 2003Jana Falkenhagen Liquid chromatography in combination with spectroscopic methods like matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) or nuclear magnetic resonance (NMR) spectroscopy is a powerful method to characterize silsesquioxanes and silsesquioxane mixtures. As new examples, the formation of silsesquioxyl-substituted silsesquioxanes [(n-octyl)7(SiO1.5)8]2O and [(n-octyl)7(SiO1.5)8O]2[(n-octyl)6(SiO1.5)8] as well as the cage rearrangement of octa-[(n-heptyl)silsesquioxane] to larger structur es [(n-heptyl)SiO1.5)]n up to n=28 are shown. Copyright © 2003 John Wiley & Sons, Ltd. [source] Two new structures in the glycine,oxalic acid systemACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010Nikolay A. Tumanov Glycinium semi-oxalate-II, C2H6NO2+·C2HO4,, (A), and diglycinium oxalate methanol disolvate, 2C2H6NO2+·C2O42,·2CH3OH, (B), are new examples in the glycine,oxalic acid family. (A) is a new polymorph of the known glycinium semi-oxalate salt, (C). Compounds (A) and (C) have a similar packing of the semi-oxalate monoanions with respect to the glycinium cations, but in (A) the two glycinium cations and the two semi-oxalate anions in the asymmetric unit are non-equivalent, and the binding of the glycinium cations to each other is radically different. Based on this difference, one can expect that, although the two forms grow concomitantly from the same batch, a transformation between (A) and (C) in the solid state should be difficult. In (B), two glycinium cations and an oxalate anion, which sits across a centre of inversion, are linked via strong short O,H...O hydrogen bonds to form the main structural fragment, similar to that in diglycinium oxalate, (D). Methanol solvent molecules are embedded between the glycinium cations of neighbouring fragments. These fragments form a three-dimensional network via N,H...O hydrogen bonds. Salts (B) and (D) can be obtained from the same solution by, respectively, slow or rapid antisolvent crystallization. [source] N,N,-Dimethylpyrazinediium bis(tetrafluoroborate) and N,N,-diethylpyrazinediium bis(tetrafluoroborate): new examples of anion,, triadsACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Jianjiang Lu Crystallization of N,N,-dimethylpyrazinediium bis(tetrafluoroborate), C6H10N22+·2BF4,, (I), and N,N,-diethylpyrazinediium bis(tetrafluoroborate), C8H14N22+·2BF4,, (II), from dried acetonitrile under argon protection has permitted their single-crystal studies. In both crystal structures, the pyrazinediium dications are located about an inversion center (located at the ring center) and each pyrazinediium aromatic ring is ,-bonded to two centrosymmetrically related BF4, anions. Strong anion,, interactions, as well as weak C,H...F hydrogen bonds, between BF4, and pyrazinediium ions are present in both salts. [source] A family of hyperbolic spin Calogero-Moser systems and the spin Toda latticesCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 6 2004L.-C. Li In this paper, we continue to develop a general scheme to study a broad class of integrable systems naturally associated with the coboundary dynamical Lie algebroids. In particular, we present a factorization method for solving the Hamiltonian flows. We also present two important classes of new examples, a family of hyperbolic spin Calogero-Moser systems and the spin Toda lattices. To illustrate our factorization theory, we show how to solve these Hamiltonian systems explicitly. © 2004 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||||||||