5,235 research outputs found
Extensive reuse of soda-lime waste glass in fly ash-based geopolymers
The possibility of extensive incorporation of soda-lime waste glass in the synthesis of fly ash-based geopolymers was investigated. Using waste glass as silica supplier avoids the use of water glass solution as chemical activator. The influence of the addition of waste glass on the microstructure and strength of fly ash-based geopolymers was studied through microstructural and mechanical characterization. Leaching analyses were also carried out. The samples were developed changing the SiO2/Al2O3 molar ratio and the molarity of the sodium hydroxide solution used as alkaline activator. The results suggest that increasing the amount of waste glass as well as increasing the molarity of the solution lead to the formation of zeolite crystalline phases and an improvement of the mechanical strength. Leaching results confirmed that the new geopolymers have the capability to immobilize heavy metal ions
Control of citrus black spot (Guignardia Citricarpa) by biological control agents and other alternative products.
Espécies de cigarrinhas-das-pastagens (Hemiptera: Cercopidae) no meio-norte do Mato Grosso.
O objetivo destre trabalho foi identificar as principais espécies de cigarrinhas-das-pastagens que ocorrem em áres produtoras de bovinos de corte no meio-norte do estado de Mato Grosso. Foram efetuadas amostragens mensais de cigarrinhas de novembro/1999 a fevereiro/2000 em cinco municípios, encontrando-se as seguintes espécies: Barra do bugres - Deois flavopicta (87%) e Mahanarva fimbriolata (13%); Colider - D. flavopicta (81%) e M. Fimbriolata (19%); Alta Floresta e São José do Rio Claro - D. flavopicta (72%) e M fimbriolata (28%); Juara - D. flavopicta (51%) e M fimbriolata (37%) e Zulia entreriana (12%)
Advanced open-celled structures from low-temperature sintering of a crystallization-resistant bioactive glass
Most materials for bone tissue engineering are in form of highly porous open-celled components (porosity > 70%) developed by means of an adequate coupling of formulations and manufacturing technologies. This paper is dedicated to porous components from BGMS10 bioactive glass, originally designed to undergo viscous flow sintering without crystallization, which is generally known to degrade the bioactivity of 45S5 bioglass. The adopted manufacturing technologies were specifically conceived to avoid any contamination and give excellent control on the microstructures by simple operations. More precisely, 'green' components were obtained by digital light processing and direct foaming of glass powders suspended in a photosensitive organic binder or in an aqueous solution, activated with an organic base, respectively. Owing to characteristic quite large sintering window of BGMS10 glass, sintering at 750 \ub0C caused the consolidation of the structures generated at room temperature, without any evidence of viscous collapse
Métodos alternativos de controle de Guignardia citricarpa e Penicillium digitatum na cultura orgânica e convencional de citros.
O Brasil é o maior produtor de laranja e o maior exportador mundial de suco concentrado. A pinta preta dos citros, causada por Guignardia citricarpa, é uma doença de grande importância econômica, principalmente para o estado de São Paulo. O interesse no controle biológico de fitopatógenos, como alternativa de controle e como forma de reduzir os problemas ocasionados pelo uso intensivo de fungicidas, tem levado ao desenvolvimento de técnicas alternativas para uma agricultura mais sustentável. O trabalho teve por objetivo avaliar o efeito de agentes de controle biológico (Bacillus subtilis e Trichoderma harzianum) e produtos alternativos (biofertilizantes e leite) no controle da pinta preta dos frutos cítricos em cultivos convencional e orgânico. Além disso, foi avaliado o efeito de Bacillus subtilis, Paenibacillus lentimorbus e Streptomyces sp. No controle de G. Citricarpa e Penicillium digitatum em pós-colheita. Os experimentos em campo foram realizados em pomar de laranja Valência e Pêra, localizados nos municípios de Conchal e Santa Eudóxia, SP, respectivamente. Em cultivo convencional de Valência foram avaliados dois biofertilizantes (Microgeo e Bio2), nas safras 2003/2004 e 2004/2005, com quinze repetições pot tratamento, sendo uma planta por repetição. As árvores foram pulverizadas em intervalos de 28 dias, sendo o início em 08/12/03, para a safra 2003/2004 e 08/11/2004, para a safra 2004/2005. Na safra 2003/2004 as concentrações utilizadas do biofertilizante Microgeo foram 0; 10; 20; 30; e 40%. Na safra 2004/2005 foram repetidos os mesmos tratamentos da safra anterior e incluído trtamento com o biofertilizante Bio2 nas concentrações de 0; 2,5; 5; 7,5 e 10%. Para as avaliações foram utilizadas uma escala de notas de 1=0,5% a 6=49% da área do fruto atacada. Os biofertilizantes apresentaram comportamento irregular, não reduzindo a severidade da doença em nenhuma das safras em estudo. Em cultivo orgânico num pomar de laranja Pêra os ensaios foram conduzidos nas safras 2004/2005 e 2005/2006, com os seguintes tratamentos: B. Subtilis (107 e 108 ufc/,L); Milhocina (0,5%) + Melaço (0,5%); T. harzianum ( 106 conídios/mL); leite cru (5%) e Microgeo. O delineamento experimental adotado e as avaliações foram as mesmas utilizadas na área convencional. Nas duas safras o leite e o B. Subtilis reduziram a severidade e apresentaram um número maior de frutos pertencentes às notas 1 e um número menor pertencentes às notas de 3 a 6. T. harzianum não foi eficiente no controle da doença. Os testes em pós-colheita foram realizados com frutos de laranja Pêra orgânica, com inoculação artificial de P. digitatum e natural de G. citricarpa. Todos os tratamentos reduziram a severidade e a incidência da podridão dos frutos causada por P. digitatum, sendo que B. subtilis e P. lentimorbus não diferiram do fungicida thiabendazole (1500microgramas/mL), quando inoculados de forma conjunta e curativa, exibindo potencial para o seu controle em pós-colheita. Para G. citricarpa os agentes de biocontrole não foram eficientes na redução da doença.Tese (Doutorado em Agronomia) - Faculdade de Ciências Agrárias, Unesp, Botucatu. Orientador: Wagner Bettiol, Embrapa Meio Ambiente
Melhoria da qualidade e produtividade de leite na Região Serrana do Rio de Janeiro
bitstream/item/81956/1/Melhoria-da-qualidade.pdfTrabalhos apresentados ao Rio Leite Serrano, Macuco, 2004
Polarization forces in water deduced from single molecule data
Intermolecular polarization interactions in water are determined using a
minimal atomic multipole model constructed with distributed polarizabilities.
Hydrogen bonding and other properties of water-water interactions are
reproduced to fine detail by only three multipoles , , and
and two polarizabilities and , which
characterize a single water molecule and are deduced from single molecule data.Comment: 4 revtex pages, 3 embedded color PS figure
Noise Enhanced Stability in Fluctuating Metastable States
We derive general equations for the nonlinear relaxation time of Brownian
diffusion in randomly switching potential with a sink. For piece-wise linear
dichotomously fluctuating potential with metastable state, we obtain the exact
average lifetime as a function of the potential parameters and the noise
intensity. Our result is valid for arbitrary white noise intensity and for
arbitrary fluctuation rate of the potential. We find noise enhanced stability
phenomenon in the system investigated: the average lifetime of the metastable
state is greater than the time obtained in the absence of additive white noise.
We obtain the parameter region of the fluctuating potential where the effect
can be observed. The system investigated also exhibits a maximum of the
lifetime as a function of the fluctuation rate of the potential.Comment: 7 pages, 5 figures, to appear in Phys. Rev. E vol. 69 (6),200
Effects of a non-universal IMF and binary parameter correlations on compact binary mergers
Binary population synthesis provides a direct way of studying the effects of
different choices of binary evolution models and initial parameter
distributions on present-day binary compact merger populations, which can then
be compared to empirical properties such as observed merger rates. Samples of
zero-age main sequence binaries to be evolved by such codes are typically
generated from an universal IMF and simple, uniform, distributions for orbital
period , mass ratio and eccentricity . More recently, however,
mounting observational evidence has suggested the non-universality of the IMF
and the existence of correlations between binary parameters. In this study, we
implement a metallicity- and redshift-dependent IMF alongside correlated
distributions for , and in order to generate representative
populations of binaries at varying redshifts, which are then evolved with the
COMPAS code in order to study the variations in merger rates and overall
population properties.Comment: 5 pages, 5 figures, 1 table. Proceedings contribution to IWARA2022,
held in Antigua, Guatemala, in September 2022. To be published by Astron.
Nac
Reference priors for high energy physics
Bayesian inferences in high energy physics often use uniform prior
distributions for parameters about which little or no information is available
before data are collected. The resulting posterior distributions are therefore
sensitive to the choice of parametrization for the problem and may even be
improper if this choice is not carefully considered. Here we describe an
extensively tested methodology, known as reference analysis, which allows one
to construct parametrization-invariant priors that embody the notion of minimal
informativeness in a mathematically well-defined sense. We apply this
methodology to general cross section measurements and show that it yields
sensible results. A recent measurement of the single top quark cross section
illustrates the relevant techniques in a realistic situation
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