Properties of Reactive Oxygen Species by Quantum Monte Carlo

The electronic properties of the oxygen molecule, in its singlet and triplet states, and of many small oxygen-containing radicals and anions have important roles in different fields of Chemistry, Biology and Atmospheric Science. Nevertheless, the electronic structure of such species is a challenge for ab-initio computational approaches because of the difficulties to correctly describe the statical and dynamical correlation effects in presence of one or more unpaired electrons. Only the highest-level quantum chemical approaches can yield reliable characterizations of their molecular properties, such as binding energies, equilibrium structures, molecular vibrations, charge distribution and polarizabilities. In this work we use the variational Monte Carlo (VMC) and the lattice regularized Monte Carlo (LRDMC) methods to investigate the equilibrium geometries and molecular properties of oxygen and oxygen reactive species. Quantum Monte Carlo methods are used in combination with the Jastrow Antisymmetrized Geminal Power (JAGP) wave function ansatz, which has been recently shown to effectively describe the statical and dynamical correlation of different molecular systems. In particular we have studied the oxygen molecule, the superoxide anion, the nitric oxide radical and anion, the hydroxyl and hydroperoxyl radicals and their corresponding anions, and the hydrotrioxyl radical. Overall, the methodology was able to correctly describe the geometrical and electronic properties of these systems, through compact but fully-optimised basis sets and with a computational cost which scales as $N^3-N^4$, where $N$ is the number of electrons. This work is therefore opening the way to the accurate study of the energetics and of the reactivity of large and complex oxygen species by first principles

Infinite average lifetime of an unstable bright state in the green fluorescent protein

The time evolution of the fluorescence intensity emitted by well-defined ensembles of Green Fluorescent Proteins has been studied by using a standard confocal microscope. In contrast with previous results obtained in single molecule experiments, the photo-bleaching of the ensemble is well described by a model based on Levy statistics. Moreover, this simple theoretical model allows us to obtain information about the energy-scales involved in the aging process.Comment: 4 pages, 4 figure

Large 2D Coulomb crystals in a radio frequency surface ion trap

We designed and operated a surface ion trap, with an ion-substrate distance of 500\mum, realized with standard printed-circuit-board techniques. The trap has been loaded with up to a few thousand Sr+ ions in the Coulomb-crystal regime. An analytical model of the pseudo-potential allowed us to determine the parameters that drive the trap into anisotropic regimes in which we obtain large (N>150) purely 2D ion Coulomb crystals. These crystals may open a simple and reliable way to experiments on quantum simulations of large 2D systems.Comment: 4 pages, 4 figure

Granulometria do milho em dietas para suinos nas fases de crescimento e crescimento-terminacao.

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Theoretical S1 \u2192S0 Absorption Energies of the Anionic Forms of Oxyluciferin by Variational Monte Carlo and Many-Body Green's Function Theory

The structures of three negatively charged forms (anionic keto-1 and enol-1 and dianionic enol-2) of oxyluciferin (OxyLuc), which are the most probable emitters responsible for the firefly bioluminescence, have been fully relaxed at the variational Monte Carlo (VMC) level. Absorption energies of the S1 \u2190 S0 vertical transition have been computed using different levels of theory, such as TDDFT, CC2, and many-body Green\u2019s function theory (MBGFT). The use of MBGFT, by means of the Bethe\u2013Salpeter (BS) formalism, on VMC structures provides results in excellent agreement with the value (2.26(8) eV) obtained by action spectroscopy experiments for the keto-1 form (2.32 eV). To unravel the role of the quality of the optimized ground-state geometry, BS excitation energies have also been computed on CASSCF geometries, inducing a non-negligible blue shift (0.08 and 0.07 eV for keto-1 and enol-1 forms, respectively) with respect to the VMC ones. Structural effects have been analyzed in terms of over- or undercorrelation along the conjugated bonds of OxyLuc by using different methods for the ground-state optimization. The relative stability of the S1 state for the keto-1 and enol-1 forms depends on the method chosen for the excited-state calculation, thus representing a fundamental caveat for any theoretical study on these systems. Finally, Kohn\u2013Sham HOMO and LUMO orbitals of enol-2 are (nearly) bound only when the dianion is embedded into a solvent (water and toluene in the present work); excited-state calculations are therefore meaningful only in the presence of a dielectric medium which localizes the electronic density. The combination of VMC for the ground-state geometry and BS formalism for the absorption spectra clearly outperforms standard TDDFT and quantum chemistry approaches

Granulometria do milho em rações para engorda de suínos.

O que e granulometria e como medi-la?; Importância da granulometria do milho para suínos; Granulometria e valor energético do milho; Granulometria e desempenho de suínos; Granulometria e ulcera esôfago-gástrica; Recomendações da granulometria do milho para suínos; Cuidados para obtenção de uma boa granulometria.bitstream/item/59505/1/CUsersPiazzonDocuments9.pd

Desbalanceamento de sexo na parcela em experimentos com aves.

studou-se a influência do desbalanceamento de sexo na parcela, em frangos de corte, emquatro idades (I) de abate: 44, 48,52 e 56 dias e cinco tamanhos de parcelas (TP): 10(PI0), 20 (P20),30(P30), 40(P40) e 50(P50) aves. O trabalho foi realizado no Centro Nacional de Pesquisa de Suínose Aves, em Concórdia, SC, em 1986, com os dados de pesagens (Pi) obtidos por simulação. Cada com-binação 1 e TP constituiu um experimento, sendo o tratamento-controle (TC) atribuído à parcela com50% machos (M) e 50% fêmeas (F). Os demais tratamentos foram organizados considerando-se todas ascombinações de sexo na parcela, mantendo-se o número de aves de um determinado sexo igual ao TC.Os graus de concordância, de enviezamento e de achatamento dos valores de Pi, com a distribuiçãonormal, foram medidos, respectivamente, pela estatística D de Lilliefors, do coeficiente de assimetria(a3) e de curtose (a4). O desbalanceamento de sexo (ds) na parcela altera o nível de significância nacomparação de tratamento, sendo o desbalanceamento com relação a machos mais prejudicial que o defêmeas. Uma diferença de aproximadamente 0,20% na média de qualquer tratamento em relação aocontrole, devido ao ds, é suficiente para alterar o nível de significância na vizinhança de Q = 0,05, emexperimentos com dez ou mais aves por parcela

Qualidade da água de chuva armazenada em cisterna utilizada na dessedentação de suínos e bovinos de corte.

Na região do Meio Oeste Catarinense tem-se incentivado a utilização de cisternas como tecnologia capaz de ofertar água aos rebanhos. A região é caracterizada por secas severas nos meses de verão. Os objetivos da pesquisa foram: monitorar variáveis físicas, químicas e microbiológicas de qualidade da água de chuva de uma cisterna; avaliar se a água armazenada possuía qualidade para dessedentação de suínos e bovinos de corte. As concentrações de nitrato, nitrito e amônia mantiveram-se de acordo com os padrões para o consumo animal. A E. coli esteve presente em algumas amostras. A quantidade de chuva e velocidade do vento influenciaram as concentrações dos elementos nitrogenados. Investigações a fim de aprofundar esse conhecimento devem ser conduzidas para que as fontes emissoras agrícolas e pecuárias não representam alto impacto negativo para a qualidade da água. A água armazenada na cisterna apresentou qualidade satisfatória para o uso na dessedentação de suínos e bovinos de corte o que corrobora a utilização da tecnologia, visando o uso eficiente da água pelas produções pecuárias

Topologically decoherence-protected qubits with trapped ions

We show that trapped ions can be used to simulate a highly symmetrical Hamiltonian with eingenstates naturally protected against local sources of decoherence. This Hamiltonian involves long range coupling between particles and provides a more efficient protection than nearest neighbor models discussed in previous works. Our results open the perspective of experimentally realizing in controlled atomic systems, complex entangled states with decoherence times up to nine orders of magnitude longer than isolated quantum systems.Comment: 4 page