A chemical Hamiltonian approach study of the basis set superposition error changes on electron densities and one- and two-center energy components

A comparision of the local effects of the basis set superposition error (BSSE) on the electron densities and energy components of three representative H-bonded complexes was carried out. The electron densities were obtained with Hartee-Fock and density functional theory versions of the chemical Hamiltonian approach (CHA) methodology. It was shown that the effects of the BSSE were common for all complexes studied. The electron density difference maps and the chemical energy component analysis (CECA) analysis confirmed that the local effects of the BSSE were different when diffuse functions were present in the calculations

Effect of basis set superposition error on the electron density of molecular complexes

The effect of basis set superposition error (BSSE) on molecular complexes is analyzed. The BSSE causes artificial delocalizations which modify the first order electron density. The mechanism of this effect is assessed for the hydrogen fluoride dimer with several basis sets. The BSSE-corrected first-order electron density is obtained using the chemical Hamiltonian approach versions of the Roothaan and Kohn-Sham equations. The corrected densities are compared to uncorrected densities based on the charge density critical points. Contour difference maps between BSSE-corrected and uncorrected densities on the molecular plane are also plotted to gain insight into the effects of BSSE correction on the electron density

One- and two-center energy components in the atoms in molecules theory

The energy decomposition scheme proposed in a recent paper has been realized by performing numerical integrations. The sample calculations carried out for some simple molecules show excellent agreement with the chemical picture of molecules, indicating that such an energy decomposition analysis can be useful from the point of view of connecting quantum mechanics with the genuine chemical concepts

C-H···O H-bonded complexes: how does basis set superposition error change their potential-energy surfaces?

Geometries, vibrational frequencies, and interaction energies of the CNH⋯O3 and HCCH⋯O3 complexes are calculated in a counterpoise-corrected (CP-corrected) potential-energy surface (PES) that corrects for the basis set superposition error (BSSE). Ab initio calculations are performed at the Hartree-Fock (HF) and second-order Møller-Plesset (MP2) levels, using the 6-31G(d,p) and D95++(d,p) basis sets. Interaction energies are presented including corrections for zero-point vibrational energy (ZPVE) and thermal correction to enthalpy at 298 K. The CP-corrected and conventional PES are compared; the unconnected PES obtained using the larger basis set including diffuse functions exhibits a double well shape, whereas use of the 6-31G(d,p) basis set leads to a flat single-well profile. The CP-corrected PES has always a multiple-well shape. In particular, it is shown that the CP-corrected PES using the smaller basis set is qualitatively analogous to that obtained with the larger basis sets, so the CP method becomes useful to correctly describe large systems, where the use of small basis sets may be necessary

Density functional energy decomposition into one- and two-atom contributions

The present work provides a generalization of Mayer's energy decomposition for the density-functional theory (DFT) case. It is shown that one- and two-atom Hartree-Fock energy components in Mayer's approach can be represented as an action of a one-atom potential VA on a one-atom density ρ A or ρ B. To treat the exchange-correlation term in the DFT energy expression in a similar way, the exchange-correlation energy density per electron is expanded into a linear combination of basis functions. Calculations carried out for a number of density functionals demonstrate that the DFT and Hartree-Fock two-atom energies agree to a reasonable extent with each other. The two-atom energies for strong covalent bonds are within the range of typical bond dissociation energies and are therefore a convenient computational tool for assessment of individual bond strength in polyatomic molecules. For nonspecific nonbonding interactions, the two-atom energies are low. They can be either repulsive or slightly attractive, but the DFT results more frequently yield small attractive values compared to the Hartree-Fock case. The hydrogen bond in the water dimer is calculated to be between the strong covalent and nonbonding interactions on the energy scale

UdGExpress

Recull de notícies de la comunitat universitària

El fenómeno de la poesía conversacional en la obra de Luis Rogelio Nogueras

El presente trabajo investigativo tiene por objeto analizar cuáles fueron las circunstancias que dieron lugar a que el fenómeno de la poesía conversacional se haga presente en la poética cubana de los años setenta, tomando como caso específico la obra de Luis Rogelio Nogueras, poeta nacido en La Habana en 1944. El desarrollo de esta tesis pretende dar cuenta de cuáles fueron las condiciones que atravesaba la poesía en los años anteriores a 1959, año del triunfo de la Revolución cubana ante la dictadura de Fulgencio Batista, lo que desencadena un proceso de constitución de un nuevo público lector así como un nuevo enfoque de la poesía. Finalmente este trabajo analizará las claves intertextuales, de contexto y contenido en las que se enmarca la obra de Luis Rogelio Nogueras, así como las características que integran la corriente poética llamada conversacional.

Optimization of a sponge cake formulation with inulin as fat replacer: structure, physicochemical, and sensory properties

The effects of several fat replacement levels (0%, 35%, 50%, 70%, and 100%) by inulin in sponge cake microstructure and physicochemical properties were studied. Oil substitution for inulin decreased significantly (P < 0.05) batter viscosity, giving heterogeneous bubbles size distributions as it was observed by light microscopy. Using confocal laser scanning microscopy the fat was observed to be located at the bubbles’ interface, enabling an optimum crumb cake structure development during baking. Cryo-SEM micrographs of cake crumbs showed a continuous matrix with embedded starch granules and coated with oil; when fat replacement levels increased, starch granules appeared as detached structures. Cakes with fat replacement up to 70% had a high crumb air cell values; they were softer and rated as acceptable by an untrained sensory panel (n = 51). So, the reformulation of a standard sponge cake recipe to obtain a new product with additional health benefits and accepted by consumers is achieved.

Effect of fat replacement by inulin on textural and structural properties of short dough biscuits

The aim of this study was to evaluate the effects of inulin as fat replacer on short dough biscuits and their corresponding doughs. A control formulation, with no replacement, and four formulations in which 10, 20, 30, and 40 % of shortening was replaced by inulin were studied. In the dough, shortening was observed surrounding flour components. At higher fat replacement levels, flour was more available for hydration leading to significant (P<0.05) harder doughs: from 2.76 (0.12)N in 10 % fat-replaced biscuits to 5.81 (1.56)N in 30 % fat-replaced ones. Biscuit structure was more continuous than dough structure. A continuous fat layer coated the matrix surface, where starch granules were embedded. In general, weight loss during baking and water activity decreased significantly (P<0.05) as fat replacement increased. Biscuit dimensions and aeration decreased when fat replacement increased, e.g., width gain was +1.20 mm in 10 fat-replaced biscuits and only +0.32 mm in 40 % fat-replaced ones. Panelist found biscuits with 20 % of fat replacement slightly harder than control biscuits. It can be concluded that shortening may be partially replaced, up to 20 %, with inulin. These low fat biscuits are similar than the control biscuits, and they can have additional health benefits derived from inulin presence.

Functionality of several cake ingredients: a comprehensive approach

The roles of some cake ingredients – oil, a leavening agent, and inulin – in the structure and physicochemical properties of batter and cakes were studied in four different formulations. Oil played an important role in the batter stability, due to its contribution to increasing batter viscosity and occluding air during mixing. The addition of the leavening agent was crucial to the final height and sponginess of the cakes. When inulin was used as a fat replacer, the absence of oil caused a decrease in the stability of the batter, where larger air bubbles were occluded. Inulin dispersed uniformly in the batter could create a competition for water with the flour components: gluten was not properly hydrated and some starch granules were not fully incorporated into the matrix. Thus, the development of a continuous network was disrupted and the cake was shorter and softer; it contained interconnected air cells in the crumb, and was easily crumbled. The structure studies were decisive to understand the physicochemical properties.

Replacing fat and sugar with inulin in cakes: bubble size distribution, physical and sensory properties

The replacement of fat and sugar in cakes is a challenge as they have an important effect on the structural and sensory properties. Moreover, there is the possibility to incorporate an additional value using novel replacers. In this work, inulin and oligofructose were used as fat and sugar replacers, respectively. Different combinations of replacement levels were investigated: fat replacement (0 and 50 %) and sugar replacement (0, 20, 30, 40 and 50 %). Simulated microbaking was carried out to study bubble size distribution during baking. Batter viscosity and weight loss during baking were also analysed. Cake characteristics were studied in terms of cell crumb structure, height, texture and sensory properties. Fat and sugar replacement gave place to batters with low apparent viscosity values. During heating, bubbles underwent a marked expansion in replaced cakes if compared to the control cake. The low batter stability in fat-replaced samples increased bubble movement, giving place to cakes with bigger cells and less height than the control. Sugar-replaced samples had smaller and fewer cells and lower height than the control. Moreover, sugar replacement decreased hardness and cohesiveness and in- creased springiness, which could be related with a denser crumb and an easily crumbled product. Regarding the sensory analysis, a replacement up to 50 % of fat and 30 % of sugar, separately and simultaneously, did not change remarkably the overall acceptability of the cakes. However, the sponginess and the sweetness could be improved in all the replaced cakes, according to the Just About Right scales.

A Formação do professor: um estudo a partir da concepção de ética em Paul Ricoeur

Pós-graduação em Educação Escolar - FCLAR

Glauber Rocha e a dimensão do confronto de ideias na cena midiática: estudo das estratégias do jovem crítico de cinema no Jornal da Bahia no final dos anos 1950

In late 1950, the young Glauber Rocha, still without having directed any of his films, becomes the main cultural critic of the Jornal da Bahia in Salvador, Bahia. His film critic activity falls within the symbolic local disputes and his texts published become an active voice in the cultural field of Bahia. With a considerable apparatus of the press in his favor, the performance of the young critic Glauber Rocha allows to discuss: the role of public intellectual and media production and dissemination of ideas by the newspapers at the turn of the 1950s to the 1960s, a time of intense political, social and cultural changes in Brazil.

Ringier (Unternehmen)

Gruppo mediatico di proprietà della fam. omonima, le cui origini risalgono alla tipografia fondata nel 1833 a Zofingen da Johann Rudolf (1803-1874). Nel 1898 Paul August Ringier, esponente della terza generazione, rilevò l'azienda, che ampliò fino a farne un'impresa tipografica industriale e una delle principali case editrici della Svizzera. Nel 1932 la Ringier fu trasformata in un gruppo, divenne una soc. anonima e fu fondata la holding. Fino al 1938 pubblicò nove riviste illustrate per fam., di intrattenimento e dedicate ai programmi radiofonici, con una tiratura complessiva di 680'000 copie; nel 1959 diede vita al Blick. Dal 1960 con Hans (1906-2003), figlio di Paul August, e dal 1985 con i suoi figli Christoph (nascita 1941; in azienda fino al 1991) e Michael (nascita 1949), l'impresa divenne il più grande gruppo mediatico della Svizzera. Dal 1980 si è espansa in Germania, Asia e negli Stati Uniti e dal 1992 nell'Europa orientale. Nel 2008 impiegava in tutto il mondo 8129 persone e la cifra d'affari ammontava a oltre 1,535 miliardi di frs. Bibliografia – P. Meier, T. Häussler, Zwischen Masse, Markt und Macht, 2009