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991.
Graminha AE Rodrigues C Batista AA Teixeira LR Fagundes ES Beraldo H 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(4):1073-1076
Reaction of [RuCl(3)(dppb)H(2)O] (dppb=1,4 bis(diphenylphospine)butane) with 2-benzoylpyridine thiosemicarbazone (H2Bz4DH) and its N(4)-methyl (H2Bz4M) and N(4)-phehyl (H2Bz4Ph) derivatives gave [RuCl(dppb)(H2Bz4DH)]Cl (1), [RuCl(dppb)(H2Bz4M)]Cl (2) and [RuCl(dppb)(H2Bz4Ph)]Cl (3). The cytotoxic activity of the studied compounds was tested against the MCF-7, TK-10 and UACC-62 human tumor cell lines. The precursor [RuCl(3)(dppb)H(2)O] exhibits cytocidal activity against the tree cell lines. H2BzDH, H2Bz4M, and [RuCl(dppb)(H2Bz4M)]Cl (2) show a selective cytocidal effect against the UACC-62 cell line which makes them the most promising compounds. 相似文献
992.
Jaume Llibre Clàudia Valls 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2010,61(4):627-634
In this paper, we study the first integrals of the Rikitake system $$\dot{x} = -\mu x + yz, \quad \dot{y} = -\mu y + x (z-a), \quad \dot{z} = 1-xy,$$ that can be described by formal power series when the system has singular points. 相似文献
993.
Size effects regarding Hall–Petch (HP) relation are studied in this work for cobalt, nickel and Fe–3wt.%Si (FeSi), from polycrystalline to multicrystalline states. The materials show a breakdown in HP plot for thickness (t) to grain size (d) ratio less than a critical value. This appears in the beginning of plasticity for cobalt and FeSi whereas a plastic strain threshold must be overcome for nickel. Measurements of the coercive field on strained samples are able to depict such modification for low t/d ratio. Values of the coercive field in the polycrystalline domain allow an estimation of the magnetocrystalline anisotropy energy, related to the grain volume fraction concerned by reversal mechanisms for magnetic domains. Multicrystalline samples of cobalt and FeSi becomes magnetically softer at the yield stress. This is linked to a delay of the maximum intergranular stress towards higher strains for FeSi. For cobalt, non-linear elasticity and strong basal texture modify the magnetoelastic effects in coarse grain samples. For nickel, size effect on the coercive field appears after a few per cent of plastic strain as for HP relationship. A mean internal stress can be captured by magnetic measurements on polycrystals, related to the intragranular part of the kinematic stress. The softening of the magnetic properties for strained nickel multicrystals is due to a competition between the apparition of dislocation cells, which increases the coercive field by mechanisms of magnetic domain wall pinning, and surface softening of multicrystals, which tends to decrease the value of Hc. 相似文献
994.
Matteo Adorisio Alberto Pezzotta Clélia de Mulatier Cristian Micheletti Antonio Celani 《Journal of statistical physics》2018,170(1):79-100
A computationally challenging and open problem is how to efficiently generate equilibrated samples of conditioned walks. We present here a general stochastic approach that allows one to produce these samples with their correct statistical weight and without rejections. The method is illustrated for a jump process conditioned to evolve within a cylindrical channel and forced to reach one of its ends. We obtain analytically the exact probability density function of the jumps and offer a direct method for gathering equilibrated samples of a random walk conditioned to stay in a channel with suitable boundary conditions. Unbiased walks of arbitrary length can thus be generated with linear computational complexity—even when the channel width is much smaller than the typical bond length of the unconditioned walk. By profiling the metric properties of the generated walks for various bond lengths we characterize the crossover between weak and strong confinement regimes with great detail. 相似文献
995.
Małgorzata Bednarska-Bzdęga Michael Krivelevich Viola Mészáros Clément Requilé 《Discrete Mathematics》2018,341(3):658-664
We consider the following two-player game, parametrised by positive integers and . The game is played between Painter and Builder, alternately taking turns, with Painter moving first. The game starts with the empty graph on vertices. In each round Painter colours a vertex of her choice by one of the colours and Builder adds an edge between two previously unconnected vertices. Both players must adhere to the restriction that the game graph is properly -coloured. The game ends if either all vertices have been coloured, or Painter has no legal move. In the former case, Painter wins the game; in the latter one, Builder is the winner. We prove that the minimal number of colours allowing Painter’s win is of logarithmic order in the number of vertices . Biased versions of the game are also considered. 相似文献
996.
This paper reports on the synthesis, characterization and photophysical properties of the Tb3+ organophosphonates, TbH(O3PR)2, methylphosphonate (R=CH3), ethylphosphonate (R=C2H5), propylphosphonate (R=C3H7), and phenylphosphonate (R=C6H5). The layered Tb3+ organophosphonates were characterized by X-ray diffraction, IR spectroscopy, TG and elemental analysis. The interlayer distances of the Tb3+ organophosphonates evaluated by the X-ray diffractogram were 9.50 Å for TbH(O3PCH3)2, 12.18 Å for TbH(O3PC2H5)2, 14.84 Å for TbH(O3PC3H7)2 and 15.20 Å for TbH(O3PC6H5)2. The Tb3+ luminescence data revealed highly green emissive materials when they were excited at 368 nm, where the characteristic 5D4 → 7F
J
(J=6, 5, 4 and 3) transitions of Tb3+ were observed at 488, 543, 585 and 619 nm, respectively. The lifetime of the Tb3+ 5D4 → 7F5 transition (λexc=368 nm and λem=543 nm) for the Tb3+ organophosphonates was evaluated from the decay curves, which values were of 2.88, 2.22, 2.14 and 2.59 ms, respectively for TbH(O3PCH3)2, TbH(O3PC2H5)2, TbH(O3PC3H7)2 and TbH(O3PC6H5)2. TG analysis revealed that these materials are thermally highly stable, with no water molecule in their composition, which makes them potential luminophores. 相似文献
997.
Caldeira Leila Rodrigues Lima Josefa Abucáter Santos Flávio Alves Lana Mary Ane Gonçalves dos Santos Rossi Ribeiro Ana Cláudia de Oliveira Elcio Cruz 《Accreditation and quality assurance》2017,22(2):91-96
Accreditation and Quality Assurance - Ractopamine is used as an animal feed additive, but its adverse effects led to the necessity of the current monitoring programs of ractopamine residues in food... 相似文献
998.
Gade LH Marconi G Dro C Ward BD Poyatos M Bellemin-Laponnaz S Wadepohl H Sorace L Poneti G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(11):3058-3075
A key feature of tris(oxazolinyl)ethane ("trisox") ligands, which have shown broad scope in asymmetric catalysis, is the orientation and steric demand of their oxazoline substituents. This, along with the modularity of their synthesis determines their coordination chemistry. The possibility to combine oxazolines, in which the stereogenic centers adjacent to the N-donor atoms have different absolute configuration, whilst retaining their ability to coordinate as tripodal ligands, has been demonstrated by the synthesis of the enantiomerically pure C3-symmetric iPr-trisox(S,S,S) and C1-symmetric iPr-trisox(S,S,R) and their reaction with [Mo(CO)3(NCMe)3] yielding [Mo{iPr-trisox(S,S,S)}(CO)3] (1 a) and [Mo{iPr-trisox(S,S,R)}(CO)3] (1 b), respectively. The non-autocomplementarity of two homochiral trisox ligands at one metal center has been demonstrated by reaction of rac-C3 iPr-trisox with one equivalent of [Co(ClO4)2].6 H2O, giving the centrosymmetric heterochiral complex [Co(iPr-trisox)2](ClO4)2 (3), whereas an analogous reaction with the enantiopure ligand yielded a mixture of Co(II) complexes, which is characterized by the total absence of a [(trisox)2Co](+/2+) ion. The scope of the trisox ligand in terms of facial coordination to both early and late transition metals was demonstrated by the synthesis and structural characterization of the mononuclear complexes [ScCl3(iPr-trisox)] (4), [Fe(tBu-trisox)(NCMe)3](BF4)2 (5), and [Ru(eta6-p-cymene)(iPr-trisox)](PF6)2 (6). The facial coordination of their three ligating atoms to a metal center may be impeded if the transition-metal center stereoelectronically strongly favors a non-deltahedral coordination sphere, which is generally the case for the heavier d8-transition-metal atoms/ions. Reaction of iPr-trisox with [Rh(cod)2]BF4 led to the formation of the 16-electron d8-configured complex [Rh(iPr-trisox)(cod)](BF4) (7), which is oxidized by CsBr3 to give the Rh(III) complex [RhBr3(iPr-trisox)] (8) possessing a C3-symmetric structure with a kappa3-N-trisox ligand. The crystalline salts [M2(mu-Cl3)(iPr-trisox)2](PF6) (M=Fe(II): 9, Co(II): 10, Ni(II): 11), were prepared by addition of one molar equivalent of iPr-trisox and an excess of KPF6 to solutions of the anhydrous (FeCl2) or hydrated metal halides (CoCl2.6 H2O, NiCl2.6 H2O). All dinuclear complexes display weak magnetic coupling. For the mononuclear species [CuCl2(iPr-trisox)] (12) the removal of a chloride anion and thus the generation of a dinuclear chloro-bridged structure failed due to Jahn-Teller destabilization of a potential octahedral coordination sphere. 相似文献
999.
Ana Paula Corrêa Argondizzo Cláudio Marcos Rocha-de-Souza Marta de Almeida Santiago Ricardo Galler Joice Neves Reis Marco Alberto Medeiros 《Applied biochemistry and biotechnology》2017,182(4):1518-1539
Streptococcus pneumoniae is a colonizer of the human nasopharynx, which accounts for most of the community-acquired pneumonia cases and can cause non-invasive and invasive diseases. Current available vaccines are serotype-specific and the use of recombinant proteins associated with virulence is an alternative to compose vaccines and to overcome these problems. In a previous work, we describe the identification of proteins in S. pneumoniae by reverse vaccinology and the genetic diversity of these proteins in clinical isolates. It was possible to purify a half of 20 selected proteins in soluble form. The expression of these proteins on the pneumococcal cells surface was confirmed by flow cytometry. We demonstrated that some of these proteins were able to bind to extracellular matrix proteins and were recognized by sera from patients with pneumococcal meningitis infection caused by several pneumococcal serotypes. In this context, our results suggest that these proteins may play a role in pneumococcal pathogenesis and might be considered as potential vaccine candidates. 相似文献
1000.
Oliveira LG Silva MM Paula FC Pereira-Maia EC Donnici CL Simone CA Frézard F Silva EN Demicheli C 《Molecules (Basel, Switzerland)》2011,16(12):10314-10323
Antimony(V) and bismuth(V) complexes of lapachol have been synthesized by the reaction of Ph?SbCl? or Ph?BiCl? with lapachol (Lp) and characterized by several physicochemical techniques such as IR, and NMR spectroscopy and X-ray crystallography. The compounds contain six-coordinated antimony and bismuth atoms. The antimony(V) complex is a monomeric derivative, (Lp)(Ph?Sb)OH, and the bismuth(V) complex is a dinuclear compound bridged by an oxygen atom, (Lp)?(Ph?Bi)?O. Both compounds inhibited the growth of a chronic myelogenous leukemia cell line and the complex of Bi(V) was about five times more active than free lapachol. This work provides a rare example of an organo-Bi(V) complex showing significant cytotoxic activity. 相似文献