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81.
Milutin M. Milosavljevi? Goran D. Vukovi? Aleksandar D. Marinkovi? Radoslav Aleksi? Petar S. Uskokovi? 《Monatshefte für Chemie / Chemical Monthly》2011,46(3):1045-1053
Abstract
Twelve N-(3- and 4-substituted phenyl)-O-isobutyl thionocarbamates, eight of which are novel, were synthesized from O-isobutyl xanthate and 3- and 4-substituted anilines in the presence of a nano-platinum aminophenyl modified multi-walled carbon nanotube catalyst. The nano-Pt catalyst was prepared on a carbon nanotube support modified by diazotization, nitro group reduction, and subsequent microwave-assisted nano-Pt precipitation. The catalyst was characterized by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, thermogravimetric analysis, and transmission electron microscopy. The nano-platinum/modified carbon nanotube catalyst was compared with a commercial Pt/active carbon catalyst in terms of product purity and yield. The results obtained by the use of the catalysts were additionally compared with those obtained by reaction of sodium isobutyl xanthogenacetate and 3- and 4-substituted anilines. Full structure characterization of the synthesized N-(substituted phenyl)-O-isobutyl thionocarbamates was achieved using FT-IR, 1H and 13C NMR, and mass spectrometric methods, and their purity was proved by elemental analysis and gas chromatography. The new catalytic method offers advantages over the commercial method, such as higher yields and no product purification is required, thus conforming to the principles of ecologically friendly syntheses. 相似文献82.
Petar T. Todorov Nikola D. Pavlov Boris L. Shivachev Rosica N. Petrova Jean Martinez Emilia D. Naydenova Monique Calmes 《Heteroatom Chemistry》2012,23(2):123-130
Novel racemic and optically active constrained N‐phosphonoalkyl bicyclic β‐amino acids have been synthesized via the Kabachnik–Fields reaction of the (RS) or (R)‐1‐aminobicyclo[2.2.2]octane‐2‐carboxylic acids with paraformaldehyde and benzaldehyde, and the dimethyl‐H‐phosphonate. The structure of obtained compounds was characterized by NMR (1H, 13C, and 31P), LC/MS, and X‐ray diffraction analyses. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:123–130, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20759 相似文献
83.
Matejić JS Dzamić AM Ristić MS Randelović VN Marin PD 《Natural product communications》2012,7(2):235-236
Cachrys cristata DC. (Apiaceace) is a rare and critically endangered species in the flora of Serbia. Essential oil isolated by hydrodistillation from the aerial parts and fruits of this species was analyzed using combined GC and GC/MS. The oil from the aerial parts was rich in sesquiterpenes (45.7%) and oxygenated sesquiterpenes (32.9%), while the fruit oil consisted of a higher percentage of sesquiterpenes (48.3%) and oxygenated sesquiterpenes (36.7%). The dominant constituents in the oil from aerial parts were phytol (13.1%) and germacrene D (12.9%), while in the fruit oil suberosin (19.7%) and germacrene D (12.3%) were the most abundant. 相似文献
84.
Aichinger et al. (2011) have proved that every finite algebra with a cube-term (equivalently, with a parallelogram-term; equivalently, having few subpowers) is finitely related. Thus finite algebras with cube terms are inherently finitely related??every expansion of the algebra by adding more operations is finitely related. In this paper, we show that conversely, if A is a finite idempotent algebra and every idempotent expansion of A is finitely related, then A has a cube-term. We present further characterizations of the class of finite idempotent algebras having cube-terms, one of which yields, for idempotent algebras with finitely many basic operations and a fixed finite universe A, a polynomial-time algorithm for determining if the algebra has a cube-term. We also determine the maximal non-finitely related idempotent clones over A. The number of these clones is finite. 相似文献
85.
In this paper we briefly review electronic properties of quantum well states in metallic films deposited on metallic substrates. We discuss the photoemission spectroscopy from QW states by addressing the questions of their energy, in-plane dispersion, dependence on supporting structure, hybridization with substrate bands, and many-body effects with accent on electron–phonon coupling. 相似文献
86.
Catarina Carvalho Víctor Dalmau Petar Marković Miklós Maróti 《Algebra Universalis》2009,60(3):293-307
We prove that the constraint languages invariant under a short sequence of Jónsson terms (containing at most three non-trivial
ternary terms) are tractable by showing that they have bounded width. This improves a previous result by Kiss and Valeriote
and presents some evidence that the Larose–Zádori conjecture holds in the congruence-distributive case.
The first author was supported by EPSRC grant EP/C54384X/1. The second author was supported by the MEC under grant TIN 2006-15387-C03-03,
the EU PASCAL Network of Excellence IST-2002-506778, and the MODNET Marie Curie Research Training Network MRTN-CT-2004-512234.
The third author was supported by grant no. 144011G of the Ministry of Science and Environment of Serbia. The fourth author
was partially supported by the Hungarian National Foundation for Scientific Research (OTKA), grant nos. T 48809 and K 60148. 相似文献
87.
Petar Liovic Marianne Francois Murray Rudman Richard Manasseh 《Journal of computational physics》2010,229(19):7520-7544
In this paper, three improvements for modelling surface tension-dominated interfacial flows using interface tracking-based solution algorithms are presented. We have developed an improved approach to curvature estimation for incorporation into modern mesh-based surface tension models such as the Continuum Surface Force (CSF) and Sharp Surface Force (SSF) models. The scheme involves generating samples of curvature estimates from the multitude of height functions that can be generated from VOF representations of interfaces, and applying quality statistics based on interface orientation and smoothness to choose optimal candidates from the samples. In this manner, the orientation-dependence of past schemes for height function-based curvature estimation is ameliorated, the use of compact stencils for efficient computation can be maintained, and robustness is enhanced even in the presence of noticeable subgrid-scale disturbances in the interface representation. For surface tension-dominated flows, the explicit capillary timestep restriction is relaxed through timescale-separated slope limiting that identifies spurious modes in curvature evolution and omits them from contributing to surface force computations, thus promoting efficiency in simulation through the use of less timesteps. Efficiency in flow simulation is further promoted by incorporating awareness of interface location into multigrid preconditioning for Krylov subspace-based solution of elliptic problems. This use of interface-cognizance in solving problems such as the Helmholtz equation and the Poisson equation enables multigrid-like convergence in discontinuous-coefficient elliptic problems without the expense of constructing the Galerkin coarse-grid operator. The key improvements in the surface tension modelling and the numerical linear algebra are also applicable to level-set-based interfacial flow simulation. 相似文献
88.
Ivan Pavlović Ivan Ćirić Petar Djekić Vlastimir Nikolić Ratko Pavlović Žarko Ćojbašić Goran Radenković 《Meccanica》2013,48(10):2467-2477
Rheological models of tested rubber blend samples, with different ratios of smut/recycled material, were developed, analyzed and discussed according to experimental data. The experimental measurements show the dynamical behavior of these samples after a short-term axial load. The rheological model of samples was assumed as a viscoelastic Voigt-Maxwell and hyperelastic Mooney-Rivlin model. Real coded genetic algorithms were implemented for optimal model parameters identification in order to minimize the difference between the real sample behavior and dynamical model output. Numerical results obtained for analyzed mixture were compared with the original sample to verify the presented method. In purpose of predicting the dynamical characteristics for desirable rubber blends, an interrelation was formed based on the concentration of recycled material in sample blends and dynamical model parameters dependence. 相似文献
89.
Todor Gramchev Petar Popivanov Massafumi Yoshino 《Annali di Matematica Pura ed Applicata》1996,170(1):103-131
Summary
In this paper we give geometrical expressions of the (non) hypoellipticity in Gevrey spaces of parabolic operators via Newton polygones. We also determine the critical Gevrey class for which the hypoellipticity holds.Partially supported by GNAFA, CNR, Italy.Partially supported by JSPS, Japan and a grant MM-410/94 with MES, Bulgaria.Partially supported by Chuo University special research fund. 相似文献
90.
Maja Radetić Vesna Ilić Vesna Vodnik Suzana Dimitrijević Petar Jovančić Zoran Šaponjić Jovan M. Nedeljković 《先进技术聚合物》2008,19(12):1816-1821
The possibility of using a corona treatment (electrical discharge at atmospheric pressure) for fiber surface activation, which can facilitate the loading of silver nanoparticles (NPs) from colloids onto the polyester (PES) and polyamide (PA) fabrics and thus improve their antibacterial properties, was studied. Bactericidal efficiency and its laundering durability on silver‐loaded fabrics for Gram‐positive bacterium Staphylococcus aureus and Gram‐negative bacterium Escherichia coli were evaluated. The fiber morphology after corona treatment and subsequent loading of silver NPs was followed by SEM. Corona‐treated fabrics loaded with silver NPs exhibited better antibacterial properties in comparison with untreated fabrics. In order to obtain acceptable laundering durability, it is necessary to use highly concentrated silver colloids. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献