Aromaticity in a Surface Deposited Cluster: Pd4_4 on TiO2_2 (110)

We report the presence of \sigma-aromaticity in a surface deposited cluster, Pd$_4$ on TiO$_2$ (110). In the gas phase, Pd$_4$ adopts a tetrahedral structure. However, surface binding promotes a flat, \sigma-aromatic cluster. This is the first time aromaticity is found in surface deposited clusters. Systems of this type emerge as a promising class of catalyst, and so realization of aromaticity in them may help to rationalize their reactivity and catalytic properties, as a function of cluster size and composition.Comment: 4 pages, 3 figure

Avaliação dos aspectos financeiros das pequenas e médias empresas: experiência russa

The aim of this study was to assess the key financials of an array of micro-sized businesses, small and medium-sized enterprises as grouped by industry. This article deals with the assessment results of such financials as the net financial result of enterprises, the proportion of profitable and loss-making enterprises, the profitability of manufactured and sold products, the current levels of profit and loss, respectively, per profitable and loss-making enterprise. The dynamics of such financials during the period from 2010 to 2014 was presented. Accounting and statistical reporting was used as the input data. In the course of this research it was proven that during that period the profitable enterprises accounted for about 80%. However, the level of profitability did not depend on the size of an enterprise. The largest proportion of profitable enterprises was noted in such sectors as education and commerce. The net financial result per employee in micro-enterprises was significantly higher than those for medium-sized enterprises and small enterprises. The results of this study may be used to validate business development plans and programs for various regions and sectors of the Russian economy. El objetivo de este estudio fue evaluar las finanzas clave de una serie de pequeñas empresas, pequeñas y medianas empresas agrupadas por industria. Este artículo trata de los resultados de la evaluación de tales finanzas como el resultado financiero neto de las empresas, la proporción de empresas rentables y que generan pérdidas, la rentabilidad de los productos fabricados y vendidos, los niveles actuales de ganancias y pérdidas, respectivamente, por rentabilidad y pérdida empresa de creación. La dinámica de tales finanzas durante el período 2010-2014 se presentó. Los informes contables y estadísticos se usaron como datos de entrada. En el curso de esta investigación, se comprobó que durante ese período las empresas rentables representaron aproximadamente el 80%. Sin embargo, el nivel de rentabilidad no depende del tamaño de una empresa. La mayor proporción de empresas rentables se observó en sectores como la educación y el comercio. El resultado financiero neto por empleado en las microempresas fue significativamente mayor que el de las medianas y pequeñas empresas. Los resultados de este estudio pueden usarse para validar planes y programas de desarrollo comercial para diversas regiones y sectores de la economía rusa. O objetivo deste estudo foi avaliar as principais finanças de uma série de microempresas, pequenas e médias empresas agrupadas por setor. Este artigo trata dos resultados da avaliação de tais finanças como o resultado financeiro líquido das empresas, a proporção de empresas lucrativas e deficitárias, a rentabilidade dos produtos fabricados e vendidos, os níveis atuais de lucros e perdas, respectivamente, por lucro e perda empresa de fabricação. A dinâmica de tais finanças durante o período de 2010 a 2014 foi apresentada. Relatórios contábeis e estatísticos foram usados como dados de entrada. No decorrer desta pesquisa, ficou provado que, durante esse período, as empresas lucrativas representavam cerca de 80%. No entanto, o nível de lucratividade não dependia do tamanho de uma empresa. A maior proporção de empresas lucrativas foi observada em setores como educação e comércio. O resultado financeiro líquido por empregado nas microempresas foi significativamente superior ao das médias empresas e pequenas empresas. Os resultados deste estudo podem ser usados para validar planos e programas de desenvolvimento de negócios para várias regiões e setores da economia russa

Ab initio prediction of Boron compounds arising from Borozene: Structural and electronic properties

Structure and electronic properties of two unusual boron clusters obtained by fusion of borozene rings has been studied by means of first principles calculations, based on the generalized-gradient approximation of the density functional theory, and the semiempirical tight-binding method was used for the transport calculations. The role of disorder has also been considered with single vacancies and substitutional atoms. Results show that the pure boron clusters are topologically planar and characterized by (3c-2e) bonds, which can explain, together with the aromaticity (estimated by means of NICS), the remarkable cohesive energy values obtained. Such feature makes these systems competitive with the most stable boron clusters to date. On the contrary, the introduction of impurities compromises stability and planarity in both cases. The energy gap values indicate that these clusters possess a semiconducting character, while when the larger system is considered, zero-values of the density of states are found exclusively within the HOMO-LUMO gap. Electron transport calculations within the Landauer formalism confirm these indications, showing semiconductor-like low bias differential conductance for these stuctures. Differences and similarities with Carbon clusters are highlighted in the discussion.Comment: 10 pages, 2 tables, 5 figure

Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XVI. A Thirteen-Year Study of Spectral Variability in NGC 5548

We present the final installment of an intensive 13-year study of variations of the optical continuum and broad H-beta emission line in the Seyfert 1 galaxy NGC 5548. The data base consists of 1530 optical continuum measurements and 1248 H-beta measurements. The H-beta variations follow the continuum variations closely, with a typical time delay of about 20 days. However, a year-by-year analysis shows that the magnitude of emission-line time delay is correlated with the mean continuum flux. We argue that the data are consistent with the simple model prediction that the size of the broad-line region is proportional to the square root of the ionizing luminosity. Moreover, the apparently linear nature of the correlation between the H-beta response time and the nonstellar optical continuum arises as a consequence of the changing shape of the continuum as it varies, specifically with the optical (5100 A) continuum luminosity proportional to the ultraviolet (1350 A) continuum luminosity to the 0.56 power.Comment: 20 pages plus 4 figures. Accepted for publication in The Astrophysical Journa

Measurement of the mass difference and the binding energy of the hypertriton and antihypertriton

According to the CPT theorem, which states that the combined operation of charge conjugation, parity transformation and time reversal must be conserved, particles and their antiparticles should have the same mass and lifetime but opposite charge and magnetic moment. Here, we test CPT symmetry in a nucleus containing a strange quark, more specifically in the hypertriton. This hypernucleus is the lightest one yet discovered and consists of a proton, a neutron, and a $\Lambda$ hyperon. With data recorded by the STAR detector{\cite{TPC,HFT,TOF}} at the Relativistic Heavy Ion Collider, we measure the $\Lambda$ hyperon binding energy $B_{\Lambda}$ for the hypertriton, and find that it differs from the widely used value{\cite{B_1973}} and from predictions{\cite{2019_weak, 1995_weak, 2002_weak, 2014_weak}}, where the hypertriton is treated as a weakly bound system. Our results place stringent constraints on the hyperon-nucleon interaction{\cite{Hammer2002, STAR-antiH3L}}, and have implications for understanding neutron star interiors, where strange matter may be present{\cite{Chatterjee2016}}. A precise comparison of the masses of the hypertriton and the antihypertriton allows us to test CPT symmetry in a nucleus with strangeness for the first time, and we observe no deviation from the expected exact symmetry