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61.
Jorge Bustamante José M. Quesada Lorena Morales de la Cruz 《Journal of Approximation Theory》2010,162(8):1495-1508
We present direct theorems for some sequences of positive linear operators in weighted spaces. The results, given in terms of some Ditzian–Totik moduli of smoothness, include estimations in norms and Becker type estimations. 相似文献
62.
63.
Antonio Casado-D��az Raquel Santiago-Mora Jos�� Manuel Quesada 《Experimental & molecular medicine》2010,42(2):87-98
Parathyroid hormone-related protein (PTHrP) is synthesized by diverse tissues, and its processing produces several fragments, each with apparently distinct autocrine and paracrine bioactivities. In bone, PTHrP appears to modulate bone formation in part through promoting osteoblast differentiation. The putative effect of PTH-like and PTH-unrelated fragments of PTHrP on human mesenchymal stem cell (MSCs) is not well known. Human MSCs were treated with PTHrP (1-36) or PTHrP (107-139) or both (each at 10 nM) in osteogenic or adipogenic medium, from the start or after 6 days of exposure to the corresponding medium, and the expression of several osteoblastogenic and adipogenic markers was analyzed. PTHrP (1-36) inhibited adipogenesis in MSCs and favoured the expression of osteogenic early markers. The opposite was observed with treatment of MSCs with PTHrP (107-139). Moreover, inhibition of the adipogenic differentiation by PTHrP (1-36) prevailed in the presence of PTHrP (107-139). The PTH/PTHrP type 1 receptor (PTH1R) gene expression was maximum in the earlier and later stages of osteogenesis and adipogenesis, respectively. While PTHrP (107-139) did not modify the PTH1R overexpression during adipogenesis, PTHrP (1-36) did inhibit it; an effect which was partially affected by PTHrP (7-34), a PTH1R antagonist, at 1 µM. These findings demonstrate that both PTHrP domains can exert varying effects on human MSCs differentiation. PTHrP (107-139) showed a tendency to favor adipogenesis, while PTHrP (1-36) induced a mild osteogenic effect in these cells, and inhibited their adipocytic commitment. This further supports the potential anabolic action of the latter peptide in humans. 相似文献
64.
We analyze some relations between classical convexities and some generalized convexities. The results are applied to obtain some new shape preserving properties of the Meyer-König and Zeller operators. 相似文献
65.
Emilia Styczeń Zygmunt Warnke Dariusz Wyrzykowski Julia K?ak Jerzy Mroziński Artur Sikorski 《Structural chemistry》2010,21(1):269-276
The crystal structures of tetrabromocobaltate(II) and tetrabromomanganate(II) salts of general formula [(C2H5)4N]2[CoBr4] (1) and [(C4H9)4N]2[MnBr4] (2) were determined. The manganese and cobalt cations are four-coordinated by bromide anions and they adopt a slightly distorted
tetrahedral coordination. In the structure of both compounds there are neither hydrogen bonds nor any unusual short-range intermolecular interactions. Magnetic measurements of the powdered samples gave negative values of the Weiss constants
equal to −4.9 and −1.1 K for (1) and (2), respectively, which suggest antiferromagnetic interactions to be transferred within the crystal lattice. 相似文献
66.
Ludivine Louise‐Leriche Emilia Pǎunescu Géraldine Saint‐André Rachid Baati Anthony Romieu Alain Wagner Pierre‐Yves Renard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(11):3510-3523
A new pro‐fluorescent probe aimed at a HTS assay of scavengers is able to selectively and efficiently cleave the P? S bond of organophosphorus nerve agents and by this provides non‐toxic phosphonic acid has been designed and synthesised. The previously described pro‐fluorescent probes were based on a conventional activated P? Oaryl bond cleavage, whereas our approach uses a self‐immolative linker strategy that allows the detection of phosphonothioase activity with respect to a non‐activated P? Salkyl bond. Further, we have also developed and optimised a high‐throughput screening assay for the selection of decontaminants (chemical or biochemical scavengers) that could efficiently hydrolyse highly toxic V ‐type nerve agents. A preliminary screening, realised on a small α‐nucleophile library, allowed us to identify some preliminary “hits”, among which pyridinealdoximes, α‐oxo oximes, hydroxamic acids and, less active but more original, amidoximes were the most promising. Their selective phosphonothioase activity has been further confirmed by using PhX as the substrate, and thus they offer new perspectives for the synthesis of more potent V nerve agent scavengers. 相似文献
67.
Nambu Y Zhao LL Morosan E Kim K Kotliar G Zajdel P Green MA Ratcliff W Rodriguez-Rivera JA Broholm C 《Physical review letters》2011,106(3):037201
Magnetism in the orthorhombic metal CaFe(4)As(3) was examined through neutron diffraction for powder and single crystalline samples. Incommensurate [q(m) ≈ (0.37-0.39) × b*] and predominantly longitudinally (|| b) modulated order develops through a 2nd order phase transition at TN = 89.63(6) K with a 3D Heisenberg-like critical exponent β = 0.365(6). A 1st order transition at T2 = 25.6(9) K is associated with the development of a transverse component, locking q(m) to 0.375(2)b*, and increasing the moments from 2.1(1) to 2.2(3) μ B for Fe2+ and from 1.3(3) to 2.4(4) μB for Fe+. The ab initio Fermi surface is consistent with a nesting instability in cross-linked FeAs strips. 相似文献
68.
França EJ Andrade CG Furlaneto-Maia L Serpa R Oliveira MT Quesada RM Furlaneto MC 《Micron (Oxford, England : 1993)》2011,42(7):726-732
Candida tropicalis has been identified as one of the most prevalent pathogenic yeast species of the Candida-non-albicans (CNA) group. Study of switching in C. tropicalis has not been the subject of extensive research. Therefore, we investigated switching event and characterized the ultrastructural architecture of different phenotypes and biofilm produced in a C. tropicalis clinical strain. Cells switched heritably, reversibly, and at a high frequency between four phenotypes readily distinguishable by the shape of colonies formed on agar at 25°C. SEM analysis was used to verify the architecture of whole Candida colonies at ultrastructural level. The smooth phenotype (parental phenotype) colony showed a hemispherical shape character, while the semi-smooth was characterized by the presence of shallow marginal depressions. The ring and rough phenotypes exhibited more complex architecture and were characterized by the presence of deep central and peripheral depressions areas. The biofilm-forming ability varied among the switch phenotypes. After 12h incubation, the smooth phenotype formed less biofilm compared to the other phenotypes (P<0.05). The electron microscopy analysis revealed that filamentation (pseudohyphae) was associated with ring and rough colonies. The ultrastructural analysis allowed the observation of the arrangement of individual cells within the colonies. At the deep central and peripheral depressions areas of the ring and rough colonies extracellular material was seen in different arrangements. The data presented here open new avenues to study a possible role for extracellular material in the formation and maintenance of the architecture of switch phenotypes in C. tropicalis. It is therefore essential that more strains be investigated to determine the biological significance of extracellular material in C. tropicalis phenotypic switching phenomenon. 相似文献
69.
A comprehensive overview on methods applied for syntheses of β-amino-α-trifluoromethyl alcohols, including stereocontrolled variants, is presented. In addition, reported cases of the exploration of β-amino-α-trifluoromethyl alcohols for the preparation of trifluoromethylated peptidomimetics and other biologically active, fluorinated compounds are discussed. Attractive opportunities for their applications as organocatalysts are also presented. 相似文献
70.