Phase diagram of a model for a binary mixture of nematic molecules on a Bethe lattice

We investigate the phase diagram of a discrete version of the Maier-Saupe model with the inclusion of additional degrees of freedom to mimic a distribution of rodlike and disklike molecules. Solutions of this problem on a Bethe lattice come from the analysis of the fixed points of a set of nonlinear recursion relations. Besides the fixed points associated with isotropic and uniaxial nematic structures, there is also a fixed point associated with a biaxial nematic structure. Due to the existence of large overlaps of the stability regions, we resorted to a scheme to calculate the free energy of these structures deep in the interior of a large Cayley tree. Both thermodynamic and dynamic-stability analyses rule out the presence of a biaxial phase, in qualitative agreement with previous mean-field results

Statistical models of mixtures with a biaxial nematic phase

We consider a simple Maier-Saupe statistical model with the inclusion of disorder degrees of freedom to mimic the phase diagram of a mixture of rod-like and disc-like molecules. A quenched distribution of shapes leads to the existence of a stable biaxial nematic phase, in qualitative agreement with experimental findings for some ternary lyotropic liquid mixtures. An annealed distribution, however, which is more adequate to liquid mixtures, precludes the stability of this biaxial phase. We then use a two-temperature formalism, and assume a separation of relaxation times, to show that a partial degree of annealing is already sufficient to stabilize a biaxial nematic structure.Comment: 11 pages, 2 figure

Generalization of Linearized Gouy-Chapman-Stern Model of Electric Double Layer for Nanostructured and Porous Electrodes: Deterministic and Stochastic Morphology

We generalize linearized Gouy-Chapman-Stern theory of electric double layer for nanostructured and morphologically disordered electrodes. Equation for capacitance is obtained using linear Gouy-Chapman (GC) or Debye-$\rm{\ddot{u}}$ckel equation for potential near complex electrode/electrolyte interface. The effect of surface morphology of an electrode on electric double layer (EDL) is obtained using "multiple scattering formalism" in surface curvature. The result for capacitance is expressed in terms of the ratio of Gouy screening length and the local principal radii of curvature of surface. We also include a contribution of compact layer, which is significant in overall prediction of capacitance. Our general results are analyzed in details for two special morphologies of electrodes, i.e. "nanoporous membrane" and "forest of nanopillars". Variations of local shapes and global size variations due to residual randomness in morphology are accounted as curvature fluctuations over a reference shape element. Particularly, the theory shows that the presence of geometrical fluctuations in porous systems causes enhanced dependence of capacitance on mean pore sizes and suppresses the magnitude of capacitance. Theory emphasizes a strong influence of overall morphology and its disorder on capacitance. Finally, our predictions are in reasonable agreement with recent experimental measurements on supercapacitive mesoporous systems

The geometry of thermodynamic control

A deeper understanding of nonequilibrium phenomena is needed to reveal the principles governing natural and synthetic molecular machines. Recent work has shown that when a thermodynamic system is driven from equilibrium then, in the linear response regime, the space of controllable parameters has a Riemannian geometry induced by a generalized friction tensor. We exploit this geometric insight to construct closed-form expressions for minimal-dissipation protocols for a particle diffusing in a one dimensional harmonic potential, where the spring constant, inverse temperature, and trap location are adjusted simultaneously. These optimal protocols are geodesics on the Riemannian manifold, and reveal that this simple model has a surprisingly rich geometry. We test these optimal protocols via a numerical implementation of the Fokker-Planck equation and demonstrate that the friction tensor arises naturally from a first order expansion in temporal derivatives of the control parameters, without appealing directly to linear response theory

Avaliacao de NPK na cultura do milho cultivado em um podzolico vermelho-escuro degradado submetido a diferentes fontes de nutrientes, no Municipio de Prados, MG.

bitstream/item/62887/1/CNPS-PESQ.-AND.-7-98.pd

Soliton surfaces associated with symmetries of ODEs written in Lax representation

The main aim of this paper is to discuss recent results on the adaptation of the Fokas-Gel'fand procedure for constructing soliton surfaces in Lie algebras, which was originally derived for PDEs [Grundland, Post 2011], to the case of integrable ODEs admitting Lax representations. We give explicit forms of the \g-valued immersion functions based on conformal symmetries involving the spectral parameter, a gauge transformation of the wave function and generalized symmetries of the linear spectral problem. The procedure is applied to a symmetry reduction of the static $\phi^4$-field equations leading to the Jacobian elliptic equation. As examples, we obtain diverse types of surfaces for different choices of Jacobian elliptic functions for a range of values of parameters.Comment: 14 Pages, 2 figures Conference Proceedings for QST7 Pragu

Seletividade de produtos fitossanitários utilizados na cultura da soja para pupas de Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae).

O objetivo do trabalho foi avaliar o efeito de produtos fitossanitários sobre pupas de Trichogramma pretiosum. Foram conduzidos três bioensaios em delineamento inteiramente casualizado com 11 tratamentos e cinco repetições. Em cada repetição, ovos de Anagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae) foram utilizados como hospedeiro alternativo, sendo aderidos em cartelas de cartolina de 1 cm2 com solução de goma arábica à 40% e oferecidos para o parasitismo por 24h. Após 168-192h do parasitismo, quando os parasitoides estavam na fase de pupa, as cartelas foram mergulhadas por cinco segundos nos tratamentos testados. Avaliou-se a sobrevivência dos indivíduos tratados e a redução na emergência dos parasitoides foi classificada segundo as normas da IOBC. Os inseticidas flufenoxurom (Cascade®) 10, diflubenzurom (Dimilin®) 20 e metoxifenozide (Intrepid 240SC®) 21,6 e 36 g i.a. ha-1 foram classificados como inócuos. Permetrina (Valon 384 CE®) 49,92; betaciflutrina 12,5 + imidacloprido 100 (Connect®) e gama-cialotrina (Stallion 150SC®) 3,75 g i.a. ha-1 foram levemente nocivos. Clorpirifós (Lorban 480BR®) 384 e espinosade (Tracer®) 24 g i.a. ha-1 foram moderadamente nocivos. Os herbicidas glifosato 720 + imazetapir 90 (Alteza®); s-metolacloro (Dual Gold®) 1920; flumioxazina (Flumyzin 500®) 60; clomazona (Gamit®) 1000; glifosato 2880 (Gliz 480SL®); dicloreto de paraquate 600 + diurom 300 (Gramocil®); glifosato 1200 (Roundup Ready®); foram classificados como inócuos e os herbicidas 2,4-D (DMA 806BR®) 1209; dicloreto de paraquate (Gramoxone®) 600; glifosato (Roundup Transorb®) 2592 g i.a. ha-1 classificados como levemente nocivos. Os fungicidas tiofanato-metílico (Cercobin 500 SC®) 400; flutriafol 60 + tiofanato-metílico 300 (Celeiro®); carbendazin (Derosal 500SC®) 250; tebuconazole (Folicur EC®) 150; flutriafol (Impact®) 125; tebuconazole 120 + trifloxistrobina 60 (Nativo®); epoxiconazole 30 + piraclostrobina 79,8 (Opera®); epoxiconazole (Opus SC®) 12,5; azoxistrobina (Priori®) 50; azoxistrobina 60 + ciproconazole 24 (Priori Xtra®) g i.a. ha-1 foram classificados como inócuos a T. pretiosum na fase de desenvolvimento avaliada (pupa). Dentre os produtos avaliados, aqueles classificados como inócuos devem ser priorizados no manejo integrado de pragas (MIP) por compatibilizar o uso do controle químico sem prejudicar o controle biológico. Do mesmo modo, os produtos classificados como moderadamente nocivos devem ser evitados sempre que possível ou substituídos por outro de menor impacto

Plasma-assisted deposition of microcapsule containing Aloe vera extract for cosmeto-textiles

There is a growing interest in the application of cosmeto-textiles to incorporate durable fragrances and skin softeners to textile.[1] Microencapsulation technology is a growing area in textile industry.[2, 3] The main disadvantage of using film-forming binders in the application of MCs onto textiles is hindrance of the active substances to be release. To overcome this issue MCs can be covalently linked onto textile substrate by using chemical or physical methods.[4] In recent years plasma technology has assumed a great importance.[5] It is a dry, environmentally- and worker-friendly method to achieve surface alteration without modifies the bulk properties of different materials.[6] It improves the fibre-matrix adhesion by introducing chemically active groups and changing the surface roughness.[7] The dielectric double barrier discharge (DBD) is one of the most effective non-thermal atmospheric plasma to improve the adsorption and adhesion of MCs in textiles [8-10]. The main objective of this study is to investigate the adhesion of MCs containing Aloe vera extract applied by padding and printing methods in a cotton/polyester (50/50) fabric (Co/PES) pre-treated with a DBD plasma discharge in air. Fabrics were analysed by contact angle, SEM and FTIR analysis. The printing and padding methods was compared in term of MCs coating efficiency, plasma dose and washing fastness.This work is supported by CSF - CAPES - Brazil (Bex 18.645-12-7) and FEDER funding on the COMPETE program and by national funds through FCT-Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136 and UID/CTM/00264.info:eu-repo/semantics/publishedVersio

Effects of leaf removal and shoot trimming on physiological and agronomic characteristics of Syrah grapevine in Northeast Brazil: preliminary results.

The São Francisco Valley, Northeast Brazil, is one of the most important wine regions with tropical conditions in the world. lt is located between parallels 8 and 1OoS, with an average annual temperature of 26.5 OC and 3,000 hours of sunshine per year. This work shows preliminary results on physiological and agronomic characteristics of Syrah vines.subjected to the practices of leaf removal and shoot trimming. The physiological and agronomical characteristics evaluated were the following: mass of cluster, mass of canes after pruning, mass of fresh and dry leaves, net photosynthesis (An), stomatal conductance (gs), intrinsic water use eficience (WUEi), leaf area (LA) and specific leaf area (SLA). The treatments did not show difJerences related to net photosynthesis (An), stomatal conductance (gs) and intrinsic water use ejJiciency (WUEi). The initial measurements of leaf area showed no difJerence between treatments. The individual leaf area was initially a.ffected by treatments, but during ripening these e.ffects were not revealed in the experimento Reverse e.ffects were observed for specific leaf area, which proved not to be a.ffected by treatments during the immature cluster phenological phase. The studies should be continued for three more seasons .in order to understand how the canopy management of Syrah, growing in a tropical environment, can injluence the agronomical and physiological plant behavior, and the implications for the quality of grapes and wines