Materiais híbridos de sílica/orgânico dopados com rodamina-B: estudo da luminescência e preparação de filmes finos para aplicações em fotônica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Surface modified Mg-doped ZnO QDs for biological imaging

Fundação Amparo à Pesquisa Estado de São Paulo (FAPESP)

Estresse salino em plantas jovens de cana-deaçúcar: respostas bioquímicas e fisiológicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Intensidade do estresse hídrico modula a expressão de aquaporinas durante a reidratação em Sorghum bicolor

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cellulose pyrolysis and quantum chemistry

Cellulose is the major constituent of most plants of interest as renewable sources of energy and is the most extensively studied form of biomass or biomass constituent. Predicting the mass loss and product yields when cellulose is subjected to increased temperature represents a fundamental problem in the thermal release of biomass energy. Unfortunately, at this time, there is no internally consistent model of cellulose pyrolysis that can organize the varied experimental data now available or provide a guide for additional experiments. Here, we present a model of direct cellulose pyrolysis using a multistage decay scheme that we first presented in the IJQC in 1984. This decay scheme can, with the help of an inverse method of assigning reaction rates, provide a reasonable account of the direct fast pyrolysis yield measurements. The model is suggestive of dissociation states of d-glucose (C6H10O5,), the fundamental cellulose monomer. The model raises the question as to whether quantum chemistry could now provide the dissociation energies for the principal breakup modes of glucose into C-1, C-2, C-3, C-4, and C-5 compounds. These calculations would help in achieving a more fundamental description of volatile generation from cellulose pyrolysis and could serve as a guide for treating hemicellulose and lignin, the other major biomass constituents. Such advances could lead to the development of a predictive science of biomass pyrolysis that would facilitate the design of liquifiers and gasifiers based upon renewable feedstocks. (C) 1998 John Wiley & Sons, Inc.

Quantum state density and critical temperature in M-theory

We discuss the asymptotic properties of quantum states density for fundamental p-branes which can yield a microscopic interpretation of the thermodynamic quantities in M-theory. The matching of the BPS part of spectrum for superstring and supermembrane gives the possibility of getting membrane's results via string calculations. In the weak coupling limit of M-theory, the critical behavior coincides with the first-order phase transition in the standard string theory at temperature less than the Hagedorn's temperature T-H. The critical temperature at large coupling constant is computed by considering M-theory on manifold with topology R-9 circle times T-2. Alternatively we argue that any finite temperature can be introduced in the framework of membrane thermodynamics.

Multipartite quantum correlations in open quantum systems

In this paper, we present a measure of quantum correlation for a multipartite system, defined as the sum of the correlations for all possible partitions. Our measure can be defined for quantum discord (QD), geometric quantum discord or even for entanglement of formation (EOF). For tripartite pure states, we show that the multipartite measures for the QD and the EOF are equivalent, which allows direct comparison of the distribution and the robustness of these correlations in open quantum systems. We study dissipative dynamics for two distinct families of entanglement: a W state and a GHZ state. We show that, for the W state, the QD is more robust than the entanglement, while for the GHZ state, this is not true. It turns out that the initial genuine multipartite entanglement present in the GHZ state makes the EOF more robust than the QD. © IOP Publishing and Deutsche Physikalische Gesellschaft.