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991.
Maximum distance separable (MDS) convolutional codes are characterized through the property that the free distance meets the generalized Singleton bound. The existence of free MDS convolutional codes over \({\mathbb {Z}}_{p^{r}}\) was recently discovered in Oued and Sole (IEEE Trans Inf Theory 59(11):7305–7313, 2013) via the Hensel lift of a cyclic code. In this paper we further investigate this important class of convolutional codes over \({\mathbb {Z}}_{p^{r}}\) from a new perspective. We introduce the notions of p-standard form and r-optimal parameters to derive a novel upper bound of Singleton type on the free distance. Moreover, we present a constructive method for building general (non necessarily free) MDS convolutional codes over \({\mathbb {Z}}_{p^{r}}\) for any given set of parameters. 相似文献
992.
We introduce the concept of distance mean-regular graph, which can be seen as a generalization of both vertex-transitive and distance-regular graphs. Let \(\Gamma \) be a graph with vertex set V, diameter D, adjacency matrix \(\varvec{A}\), and adjacency algebra \(\mathcal{A}\). Then, \(\Gamma \) is distance mean-regular when, for a given \(u\in V\), the averages of the intersection numbers \(p_{ij}^h(u,v)=|\Gamma _i(u)\cap \Gamma _j(v)|\) (number of vertices at distance i from u and distance j from v) computed over all vertices v at a given distance \(h\in \{0,1,\ldots ,D\}\) from u, do not depend on u. In this work we study some properties and characterizations of these graphs. For instance, it is shown that a distance mean-regular graph is always distance degree-regular, and we give a condition for the converse to be also true. Some algebraic and spectral properties of distance mean-regular graphs are also investigated. We show that, for distance mean regular-graphs, the role of the distance matrices of distance-regular graphs is played for the so-called distance mean-regular matrices. These matrices are computed from a sequence of orthogonal polynomials evaluated at the adjacency matrix of \(\Gamma \) and, hence, they generate a subalgebra of \(\mathcal{A}\). Some other algebras associated to distance mean-regular graphs are also characterized. 相似文献
993.
Laura M. Sanchez Gustavo Pasquale ngel Sathicq Diego Ruiz Jorge Jios Andrea L. Ferreira de Souza Gustavo P. Romanelli 《Heteroatom Chemistry》2016,27(5):295-305
Several dihydropyrimidinones/thiones, 1,4‐dihydropyridines, and pyridine derivatives were prepared in very good yields and purity values. The corresponding reactions were carried out by employing a bulk Preyssler heteropolyacid H14[NaP5W29MoO110] as an efficient and recyclable catalyst. The preparation of pyridine derivatives was carried out not through a usual procedure, i.e., the opening of the γ‐pyrone ring of 3‐formylchromone. In general, reactions took place in solvent‐free conditions at 80°C during short reaction times. 相似文献
994.
Simone Farias Diego A. Mayer Débora de Oliveira Selene M. A. Guelli U. de Souza Antônio Augusto Ulson de Souza 《Applied biochemistry and biotechnology》2017,182(4):1290-1306
The aim of this work was to remove the dyes Reactive Blue 221 (RB 221) and Reactive Blue 198 (RB 198) of synthetic effluent using the immobilized enzyme horseradish peroxidase (HRP) in Ca-alginate beads. Experimental parameters affecting the dye removal process such as the effect of pH, temperature, hydrogen peroxide concentration, mass capsules, and reuse were evaluated, and a numerical model of mass transfer was developed. A maximum removal of 93 and 75%, respectively, for the dyes RB 221 and RB 198, at pH 5.5 and temperature of 30 °C, concentration of hydrogen peroxide of 43.75 μM for dye RB 221 and 37.5 μM for the dye of RB 198 was obtained. A removal reaction of 180 min for RB 221 and 240 min for RB 198 was observed. Three reuse cycles of use of immobilized enzyme were achieved for both dyes. The numerical model proposed led to a good fit compared to experimental data. The HRP enzyme immobilized in Ca-alginate capsules showed a great potential for biotechnological applications, especially for the removal of reactive dyes. 相似文献
995.
Diego B. Menezes Osiris A. V. Brazil Luiz F. Romanholo-Ferreira Maria de Lourdes T. M. Polizeli Denise S. Ruzene Daniel P. Silva Luiz P. Costa Maria Lucila Hernández-Macedo 《Cellulose (London, England)》2017,24(10):4355-4365
Microorganisms play an important role in the bioconversion of organic residues and have therefore become promising for obtaining value-added enzymes. In an attempt to take advantage of the by-products and residues of bioconversion, this work sought to use lignocellulosic fractions extracted from corncob as fermentation substrate for ligninase induction by Pleurotus sajor-caju. To obtain the corncob lignocellulosic fractions, biomass was submitted to treatment by alkaline extraction (NaOH 0.75 mol L?1, 55 °C for 2 h) and organosolv (40% ethanol/water, 185 °C for 20 min). The in natura biomass and lignocellulosic fractions were used as substrates in the subsequent fermentation processes: 2% in natura corncob; 2% cellulose–lignin complex fraction; 2% lignin-enriched fraction; 1% lignin-enriched fraction; and synthetic medium fungal (SMF) as standard. Chemical and physical–chemical analyses indicated the effectiveness of the lignocellulosic extraction process. According to the results, the developed system promoted the induction of ligninases by P. sajor-caju. The enzymatic analysis showed laccase production (768 U L?1) using the 1% lignin-enriched fraction as substrate. Manganese peroxidase production was 1050 U L?1 with the use of the 2% lignin-enriched fraction. The presence of lignocellulosic fractions extracted from corncob’s lignin-enriched fraction in the culture medium favored the induction of ligninases in comparison to the use of residue alone. 相似文献
996.
Dr. Zhongshu Li Dr. Xiaodan Chen Dr. Diego M. Andrada Prof. Dr. Gernot Frenking Dr. Zoltán Benkö Yaqi Li Assoc. Prof. Dr. Jeffrey R. Harmer Prof. Dr. Cheng-Yong Su Prof. Dr. Hansjörg Grützmacher 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5838-5843
Carbon phosphides, CnPm, may have highly promising electronic, optical, and mechanical properties, but they are experimentally almost unexplored materials. Phosphaheteroallenes stabilized by N-heterocyclic carbenes undergo a one-electron reduction to yield compounds of the type (L)2C2P2 with diverse structures. The use of imidazolylidenes as ligands L give complexes with a central four-membered ring C2P2, while more electrophilic cyclic diamidocarbenes (DAC) give a compound with an acyclic π-conjugated CP−PC unit. Cyclic C2P2 compounds are best described as non-Kekulé molecules that are stabilized by coordination to the NHC ligands NHC→(C2P2)←NHC. These species can be easily oxidized to give stable radical cations [(NHC)2C2P2]+.. The remarkably stable molecules with an acylic C2P2 core are best described with electron-sharing bonds (DAC)=C=P−P=C=(DAC). 相似文献
997.
Guadalupe del C. Pizarro Oscar G. Marambio Manuel Jeria-Orell Diego P. Oyarzún Rudy Martin-Trasanco Julio Sánchez 《International Journal of Polymer Analysis and Characterization》2017,22(8):741-751
This work focuses on an optical and morphological comparative study of hybrid functional polymer porous films on glass substrates using the spin coating technique. The covering of these membranes, by a predeposited Zn2+ seed layer, was done applying the dip casting technique, which allows the synthesis of a large area and the control of the orientation of ZnO nanoparticles. It was possible to observe changes on the optical properties and surface morphology, which were attributed to both the spatial structure of the macromolecule and their interaction with the inorganic nanoparticles. It was also clear that hybrid porous matrices exhibit a blueshift with decreasing particle size. 相似文献
998.
Development of an ultrasensitive stacking technique for 5‐nitroimidazole determination in untreated biological fluids by micellar electrokinetic chromatography
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Maykel Hernández‐Mesa Diego Airado‐Rodríguez Ana M. García‐Campaña Carmen Cruces‐Blanco 《Electrophoresis》2015,36(20):2538-2541
Cation‐selective exhaustive injection and sweeping followed by a MEKC separation is evaluated for the sensitive analysis of 5‐nitroimidazoles in untreated human serum and urine. Deproteinized serum and urine samples were diluted 76 and 143 times, respectively, in a low‐conductivity solvent (5.00 mM orthophosphoric acid containing 5.0% v/v methanol). Samples were electrokinetically injected at 9.8 kV for 632 s in a previously conditioned fused‐silica capillary (65.0 cm × 50 μm id). Separation was performed at –30 kV and 20°C using 44 mM phosphate buffer (pH 2.5), 123 mM SDS, and 8% v/v tetrahydrofurane as BGE. Signals were monitored at 276 nm and peak area was selected as analytical response. Good linearity (R2 ≥ 0.988) and LODs lower than 1.5 and 1.8 μg/mL were achieved in serum and urine, respectively. 相似文献
999.
Mónica B. Gramajo de Doz Carlos M. Bonatti María C. Lucena Diego A. González 《Journal of solution chemistry》2013,42(1):44-51
Liquid–liquid equilibria of the methanol + ethylbenzene + methylcyclohexane ternary system are reported at 278.15, 283.15, and 293.15 K. The effect of the temperature on the liquid–liquid equilibrium is discussed. All chemical concentrations were quantified by gas chromatography using a thermal conductivity detector. Experimental data for the ternary system are compared with values calculated by the NRTL and UNIQUAC equations. It was found that both equations gave comparable quality representations of the experimental data for this ternary system. Distribution curves were also analyzed. Data for the ternary system is available from the literature at 303.15 K. 相似文献
1000.
Matthias Laubenstein Wolfango Plastino Pavel P. Povinec Valeria Fabbri Piergiorgio Aprili Marco Balata Francesco Bella Angela Cardarelli Massimiliano De Deo Benedetto Gallese Luca Ioannucci Stefano Nisi Diego Antonecchia Christian Del Pinto Giuseppe Giarrusso 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(1):317-323
Radionuclide maps of the Molise region were created for the first time using gamma-ray spectrometry analysis of 205 soil samples. The geographical distributions of 40K, 232Th and 238U were within the world average values for soils. 40K was distributed homogeneously with a slight enhancement along the coastline. The decay chains of 238U and 232Th were in secular equilibrium with their daughters, also showing a homogeneous distribution except for localized areas of enhanced concentrations close to the borders with the Lazio and the Campania regions. Concentrations of all three radionuclides were correlated with geological and pedological characteristics of soils. The measured external gamma-dose rate in the air due to naturally occurring radionuclides in the soil, and the dose rate due to cosmic rays were in agreement with values measured in other Mediterranean regions. Increased 137Cs levels from atmospheric nuclear weapons tests and the Chernobyl fallout were found at sites above 1,000 m a.s.l. 相似文献