999 resultados para Sialomucin Complex


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This article extends the theory of entrepreneurial opportunity exploitation, outlining how under certain conditions, opportunity exploitation is dependent on market making innovations. Where adverse selection and moral hazard characterize markets, consumers are likely to withdraw regardless of product quality. In order to overcome consumer resistance, entrepreneurs must signal credible commitments. But because consumers purchase without fully specifying requirements, entrepreneurs' commitments take the partial form of implicit contracts, creating strong mutual commitments to repeated transactions. These commitments enable novel markets to function, but introduce additional costs. This article illustrates the theory with the historic case of Singer in sewing machines

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Time-resolved studies of chlorosilylene, ClSiH, generated by the 193 nm laser flash photolysis of 1-chloro-1- silacyclopent-3-ene, have been carried out to obtain rate constants for its bimolecular reaction with trimethylsilane-1-d, Me3SiD, in the gas phase. The reaction was studied at total pressures up to 100 Torr (with and without added SF6) over the temperature range of 295−407 K. The rate constants were found to be pressure independent and gave the following Arrhenius equation: log[(k/(cm3 molecule−1 s−1)] = (−13.22 ± 0.15) + [(13.20 ± 1.00) kJ mol−1]/(RT ln 10). When compared with previously published kinetic data for the reaction of ClSiH with Me3SiH, kinetic isotope effects, kD/kH, in the range from 7.4 (297 K) to 6.4 (407 K) were obtained. These far exceed values of 0.4−0.5 estimated for a single-step insertion process. Quantum chemical calculations (G3MP2B3 level) confirm not only the involvement of an intermediate complex, but also the existence of a low-energy internal isomerization pathway which can scramble the D and H atom labels. By means of Rice−Ramsperger−Kassel−Marcus modeling and a necessary (but small) refinement of the energy surface, we have shown that this mechanism can reproduce closely the experimental isotope effects. These findings provide the first experimental evidence for the isomerization pathway and thereby offer the most concrete evidence to date for the existence of intermediate complexes in the insertion reactions of silylenes.

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We examined complex geographical patterns in the morphology of a kleptoparasitic spider, Argyrodes kumadai, across its distributional range in Japan. To disentangle biotic and abiotic factors underlying morphological variation, latitudinal trends were investigated in two traits, body size and relative leg length, across separate transition zones for host use and voltinism. Statistical analyses revealed complex sawtooth clines. Adult body size dramatically changed at the transition zones for host use and voltinism, and exhibited a latitudinal decline following the converse to Bergmann’s cline under the same host use and voltinism in both sexes. A similar pattern was observed for relative leg length in females but not in males. A genetic basis for a part of observed differences in morphology was supported by a common-garden experiment. Our data suggest that local adaptation to factors other than season length such as resource availability (here associated with host use) obscures underlying responses to latitude.

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In 'Avalanche', an object is lowered, players staying in contact throughout. Normally the task is easily accomplished. However, with larger groups counter-intuitive behaviours appear. The paper proposes a formal theory for the underlying causal mechanisms. The aim is to not only provide an explicit, testable hypothesis for the source of the observed modes of behaviour-but also to exemplify the contribution that formal theory building can make to understanding complex social phenomena. Mapping reveals the importance of geometry to the Avalanche game; each player has a pair of balancing loops, one involved in lowering the object, the other ensuring contact. For more players, sets of balancing loops interact and these can allow dominance by reinforcing loops, causing the system to chase upwards towards an ever-increasing goal. However, a series of other effects concerning human physiology and behaviour (HPB) is posited as playing a role. The hypothesis is therefore rigorously tested using simulation. For simplicity a 'One Degree of Freedom' case is examined, allowing all of the effects to be included whilst rendering the analysis more transparent. Formulation and experimentation with the model gives insight into the behaviours. Multi-dimensional rate/level analysis indicates that there is only a narrow region in which the system is able to move downwards. Model runs reproduce the single 'desired' mode of behaviour and all three of the observed 'problematic' ones. Sensitivity analysis gives further insight into the system's modes and their causes. Behaviour is seen to arise only when the geometric effects apply (number of players greater than degrees of freedom of object) in combination with a range of HPB effects. An analogy exists between the co-operative behaviour required here and various examples: conflicting strategic objectives in organizations; Prisoners' Dilemma and integrated bargaining situations. Additionally, the game may be relatable in more direct algebraic terms to situations involving companies in which the resulting behaviours are mediated by market regulations. Finally, comment is offered on the inadequacy of some forms of theory building and the case is made for formal theory building involving the use of models, analysis and plausible explanations to create deep understanding of social phenomena.

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Although most researchers recognise that the language repertoire of bilinguals canmvary, few studies have tried to address variation in bilingual competence in any detail. This study aims to take a first step towards further understanding the way in which bilingual competencies can vary at the level of syntax by comparing the use of syntactic embeddings among three different groups of Turkish�German bilinguals. The approach of the present paper is new in that different groups of bilinguals are compared with each other, and not only with monolingual speakers, as is common in most studies in the field. The analysis focuses on differences in the use of embeddings in Turkish, which are generally considered to be one of the more complex aspects of Turkish grammar. The study shows that young Turkish� German bilingual adults who were born and raised in Germany use fewer, and less complex embeddings than Turkish�German bilingual returnees who had lived in Turkey for eight years at the time of recording. The present study provides new insights in the nature of bilingual competence, as well as a new perspective on syntactic change in immigrant Turkish as spoken in Europe.

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A penta-nuclear. star-shaped hetero-metallic compound containing a unique Ni4KO8 core has been synthesized. The X-ray single crystal structure analysis reveals that in the complex, [K(Ni(LH)(2))(4)(OH2)(8)](Br)(ClO4)(8)center dot 11H(2)O (LH=(CH3)(2)HN+(CH2)(3)N=CHC6H4O-) the eight coordinate central K+ ion is encapsulated by four terminal [Ni(LH)(2)](2+) units through the double water bridges between K+ and each Ni(II) ions.

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A diphenoxido-bridged dinuclear copper(II) complex, [Cu2L2(ClO4)(2)] (1), has been synthesized using a tridentate reduced Schiff base ligand, 2-[[2-(diethylamino)-ethylamino]methyl]phenol (HL). The addition of triethylamine to the methanolic solution of this complex produced a novel triple bridged (double phenoxido and single hydroxido) dinuclear copper(II) complex, [Cu2L2(OH)]ClO4 (2). Both complexes 1 and 2 were characterized by X-ray structural analyses, variable-temperature magnetic susceptibility measurements, and spectroscopic methods. In 1, the two phenoxido bridges are equatorial-equatorial and the species shows strong antiferromagnetic coupling with J = -615.6(6.1) cm(-1). The inclusion of the equatorial-equatorial hydroxido bridge in 2 changes the Cu center dot center dot center dot Cu distance from 3.018 angstrom (avg.) to 2.798 angstrom (avg.), the positions of the phenoxido bridges to axial-equatorial, and the magnetic coupling to ferromagnetic with J = 50.1(1.4) cm(-1). Using 3,5-di-tert-butylcatechol as the substrate, the catecholase activity of the complexes has been studied in a methanol solution; compound 2 shows higher catecholase activity (k(cat) = 233.4 h(-1)) than compound 1 (k(cat) = 93.6 h(-1)). Both complexes generate identical species in solution, and they are interconvertible simply by changing the pH of their solutions. The higher catecholase activity of 2 seems to be due to the presence of the OH group, which increases the pH of its solution.

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The mononuclear oxidovanadium(V) complex VO(OEt)L (2), where L2- is the dianion of a diprotic tridentate ONO donor ligand, 2-hydroxyacetophenone-2-aminobenzoylhydrazone (H2L), has been synthesized by oxido-bridge splitting of the corresponding binuclear complex V2O3L2 (1) and structurally characterized by single crystal X-ray diffraction analysis, together with electrochemical and spectral studies. Splitting of the oxido-bridge was effected by refluxing 1 with excess triphenylphosphine in ethanol medium. The crystal structure of 2 is compared with that of the precursor binuclear complex 1.

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New monometallic complex salts of the form X-2[M(L)(2)] [M = Ni2+, X = (CH3)(2)NH2+(1); M = Ni2+, X = (CH3)(4)N+ (2); M = Ni2+, X = (C2H5)(4)N+(3); M = Ni2+, X = (C3H7)(4)N+(4); M = Ni2+; X = (C6H13)(4)N+) (5); M = Pd2+,X = (CH3)(2)NH2+(6); M = Pd2+, X= (C2H5)(4)N+(7); M = Pd2+, X= (C3H7)(4)N+(8); M = Pd2+, X = (C6H13)(4)N+ (9); M = Pt2+, X = (CH3)(2)NH2+(10); L = p-tolylsulfonyldithiocarbimate (CH3C6H4SO2N=CS22 )] have been prepared and characterized by elemental analysis, IR, H-1 and C-13 NMR and UV-Vis spectroscopy; 1, 3, 4 and 5 by X-ray crystallography. In 1, 3, 4 and 5, the Ni atom is four coordinate with a square planar environment being bonded to four sulfur atoms from two bidentate ligands. All the salts are weakly conducting (sigma(rt) = 10 (7) to 10 (14) Scm (1)) because of the lack of significant S center dot center dot center dot S intermolecular interactions between complex anions [M(L)(2)](2) in the solid state however, they show behavior of semiconductors in the temperature range 353-453 K. All the Pd(II) and Pt(II) salts exhibited phtotolumeniscent emissions near visible region in solution at room temperature.

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This work reports the ligational behavior of the neutral bidentate chelating molecule 2-(3,5-dimethyl pyrazol-1-yl) benzothiazole towards the oxomolybdenum(V) center. Both mononuclear complexes of the type (MoOX3L)-O-V and binuclear complexes of the formula (Mo2O4X2L2)-O-V (where X = Cl, Br) are isolated in the solid state. The complexes are characterized by elemental analyses, various spectroscopic techniques (UV-Vis IR), magnetic susceptibility measurement at room temperature, and cyclic voltammetry for their redox behavior at a platinum electrode in CH3CN. The mononuclear complexes (MoOX3L)-O-V are found to be paramagnetic while the binuclear complexes Mo2O4X2L2 are diamagnetic. Crystal and molecular structure of the ligand and the dioxomolybdenum complex (MoO2Br2L)-O-VI (obtained from the complex MoOBr3L during crystallization) have been solved by single crystal X-ray diffraction technique. Relevant DFT calculations of the ligand and the complex (MoO2Br2L)-O-VI are also carried out.

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A 1,1' bis(diphenyl phosphino ferrocene) dioxide complex of the uranyl dichloride was synthesized and characterized by elemental analysis, H-1, P-31{H-1} NMR and X-ray diffraction methods. The structure of the compound shows that the uranium(VI) ion is surrounded by four oxygen and two chlorine atoms in an octahedral geometry. Two oxygen atoms from the bis (diphenyl phosphino ferrocene) dioxide and two chlorine atoms form a square planar arrangement. Two uranyl oxygen atoms occupy the axial positions. The bis(diphenyl phosphino ferrocene) dioxide ligand acts as a bidentate chelating ligand with a bite angle of 82.90(16)degrees around the uranyl group. The two chlorine atoms are mutually cis with a CI-U-Cl angle of 97.75(7)degrees.

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The synthesis and structural characterization of a novel oxoperoxovanadium(v) complex [VO(O-2)(PAH)-(phen)] containing the ligands 2-phenylacetohydroxamic acid (PAHH) and 1,10-phenanthroline (phen) has been accomplished. The oxoperoxovanadium(v) complex was found to mimic both vanadate-dependent haloperoxidase (VHPO) activity as well as nuclease activity through effective interaction with DNA. The complex is the first example of a structurally characterized stable oxoperoxovanadium(v) complex with a coordinated bi-dentate hydroximate moiety (-CONHO-) from 2-phenylacetohydroximate (PAH). The oxoperoxovanadium(v) complex has been used as catalyst for the peroxidative bromination reaction of some unsaturated alcohols (e.g. 4-pentene-1-ol, 1-octene-3-ol and 9-decene-1-ol) in the presence of H2O2 and KBr. The catalytic products have been characterized by GC-MS analysis and spectrophotometric methods. The DNA binding of this complex has been established with CT DNA whereas the DNA cleavage was demonstrated with plasmid DNA. The interactions of the complex with DNA have been monitored by electronic absorption and fluorescence emission spectroscopy. Viscometric measurements suggest that the compound is a DNA intercalator. The nuclease activity of this complex was confirmed by gel electrophoresis studies.

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A new tetranuclear complex, [Cu4L4](ClO4)4·2H2O (1), has been synthesized from the self-assembly of copper(II) perchlorate and the tridentate Schiff base ligand (2E,3E)-3-(2-aminopropylimino) butan-2-one oxime (HL). Single-crystal X-ray diffraction studies reveal that complex 1 consists of a Cu4(NO)4 core where the four copper(II) centers having square pyramidal environment are arranged in a distorted tetrahedral geometry. They are linked together by a rare bridging mode (μ3-η1,η2,η1) of oximato ligands. Analysis of magnetic susceptibility data indicates moderate antiferromagnetic (J1 = −48 cm−1, J2 = −40 cm−1 and J3 = −52 cm−1) exchange interaction through σ-superexchange pathways (in-plane bridging) of the oxime group. Theoretical calculations based on DFT technique have been used to obtain the energy states of different spin configurations and estimate the coupling constants and to understand the exact magnetic exchange pathways.

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The epoxide ring in 5,6-dihydro-5,6-epoxy-1,10-phenanthroline (L) opens up in its reaction with 4-methylaniline and 4-methoxyaniline in water in equimolar proportion at room temperature without any Lewis acid catalyst to give a monohydrate of 6-(4-methyl-phenylamino)-5,6-dihydro-1,10-phenanthrolin-5-ol (L′·H2O) and 6-(4-methoxyphenyl-amino)-5,6-dihydro-1,10-phenanthrolin-5-ol (L″) respectively. Reaction time decreases from 72 to 14 h in boiling water. But the yields become less. Reaction of L with Zn(ClO4)2·6H2O in methanol in 3:1 molar ratio at room temperature affords white [ZnL3](ClO4)2·H2O. The X-ray crystal structure of the acetonitrile solvate [ZnL3](ClO4)2·MeCN has been determined which shows that the metal has a distorted octahedral N6 coordination sphere. [ZnL3](ClO4)2·2H2O reacts with 4-methylaniline and 4-methoxyaniline in boiling water in 1:3 molar proportion in the absence of any Lewis acid catalyst to produce [ZnL′3](ClO4)2·4H2O and [ZnL″3](ClO4)2·H2O, respectively in 1–4 h time in somewhat low yield. In the 1H NMR spectra of [ZnL′3](ClO4)2·4H2O and [ZnL″3](ClO4)2·H2O, only one sharp methyl signal is observed implicating that only one diastereomer out of the 23 possibilities is formed. The same diastereomers are obtained when L′·H2O and L″ are reacted directly with Zn(ClO4)2·6H2O in tetrahydrofuran at room temperature in very good yields. Reactions of L′·H2O and L″ with Ru(phen)2Cl2·2H2O (phen = 1,10-phenanthroline) in equimolar proportion in methanol–water mixture under refluxing condition lead to the isolation of two diastereomers of [Ru(phen)2L′](ClO4)2·2H2O and [Ru(phen)2L″](ClO4)2·2H2O.

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Cobalt(III) complexes of diacetyl monooxime benzoyl hydrazone (dmoBH(2)) and diacetyl monooxime isonicotinoyl hydrazone (dmoInH(2)) have been synthesized and characterized by elemental analyses and spectroscopic methods. The X-ray crystal structures of the two hydrazone ligands, as well as that of the cobalt(III) complex [Co(III)(dmoInH)(2)]Cl center dot 2H(2)O, are also reported. It is found that in the cobalt(III) complexes the Co(III) ion is hexa-coordinated, the hydrazone ligands behaving as mono-anionic tridentate O,N,N donors. In the [Co(III)(dmoInH) (2)]Cl center dot 2H(2)O complex, the amide and the oxime hydrogens are deprotonated for both the ligands, while the isonicotine nitrogens are protonated. In the [Co(III)(d-moBH)(2)] Cl complex, only the amide nitrogens are deprotonated. It is shown that the additional hydrogen bonding capability of the isonicotine nitrogen results in different conformation and supramolecular structure for dmoInH(2), compared to dmoBH(2), in the solid state. Comparing the structure of the [CoIII(dmoInH)(2)]Cl center dot 2H(2)O with that of the Zn(II) complex of the same ligand, reported earlier, it is seen that the metal ion has a profound influence on the supramolecular structure, due to change in geometrical dispositions of the chelate rings.