Drug complexation and physicochemical properties of vinylpyrrolidone-N, N′-dimethylacrylamide copolymers

Solid dispersions of the nonsteriodal antiin-flammatory drug (NSAID) 2′,4′-difluoro-4-hydroxy-(1,1′-biphenyl)-3-carboxylic acid (DIF) with the water-soluble random copolymer poly(N-vinyl-2-pyrrolidone-co-N, N′-dimethylacrylamide) (VP-co-DMAm) were prepared by the solvent method (coevaporates) and melting DIP/VP-co-DMAm (cofused) physical mixtures. Differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to elucidate the possible interaction between the NSAID drug and VP-co-DMAm in cofused and coevaporated polymer-drug solid dispersions. The XRD and FTIR studies suggest the presence of physical interactions with formation of a charge transfer complex between DIF and the VP-co-DMAm copolymers as a consequence of the coevaporation or cofusion processes. In solution, dynamic and equilibrium solubility studies were determined to elucidate the mechanism of interaction between DIP and VP-co-DMAm copolymers. Thermodynamics data about the DIP: VP-co-DMAm dissolution process indicate that the coevaporated systems are more stable that the cofused systems. The dissolution of the cofused and coevaporated systems was diffusion controlled and the dissolution kinetics followed the Noyes-Whitney and the Levich equations. Molecular simulations using semiempirical quantum chemical calculations reinforce the experimental results, suggesting that the improvement in the DIF solubility could be attributed to the charge transfer complex formation between the drug and VP-co-DMAm copolymers.Fil: De Queiroz, Alvaro A.A.. Universidade Federal de Itajubá; BrasilFil: França, Écio J.. Universidade Federal de Itajubá; BrasilFil: Abraham, Gustavo Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Roman, Julio San. Instituto en Ciencia y Tecnología de Polímeros; Españ

Growth of arabica coffee cultivars submitted to glyphosate doses

Avaliaram-se, neste trabalho, os efeitos do glyphosate sobre o crescimento de três cultivares de café arábica. Utilizou-se o esquema fatorial (3 x 5) em delineamento de blocos casualizados, com quatro repetições, sendo os tratamentos compostos por três cultivares de café: Catucaí Amarelo (2 SL), Oeiras (MG-6851) e Topázio (MG-1190) e cinco doses de glyphosate (0; 57,6; 115,2; 230,4; e 460,8 g ha-1). O herbicida foi aplicado quando as plantas de café se apresentavam com 21 pares de folhas e de forma que não atingisse o terço superior delas. Aos 45 e 120 dias após a aplicação do glyphosate (DAA), avaliaram-se os incrementos na altura, na área foliar, no diâmetro do caule, no número de folhas e nos ramos plagiotrópicos, sendo eles mensurados inicialmente no dia da aplicação do herbicida; aos 10, 45 e 120 DAA, avaliou-se a porcentagem de intoxicação das plantas. A massa da matéria seca de folhas, raízes e caule, a densidade e o comprimento radicular foram avaliados aos 120 DAA. Os sintomas de intoxicação das plantas de café causados pelo glyphosate foram semelhantes nos diferentes cultivares, sendo caracterizados por clorose e estreitamento do limbo foliar. Os incrementos no número de folhas e ramos plagiotrópicos e no diâmetro do caule, independentemente do cultivar, não foram alterados pelo glyphosate. O cultivar Topázio foi o mais sensível ao glyphosate quanto a acúmulo de área foliar, de massa de matéria seca e densidade radicular.This study evaluated the effects of glyphosate on the growth of three arabica coffee cultivars. A factorial (3 x 5) was arranged in a randomized block design with four replications, with treatments consisting of three coffee varieties: Catucaí Amarelo (2 SL), Oeiras (MG-6851) and Topázio (MG-1190) and five glyphosate doses (0, 57.6, 115.2, 230.4 and 460.8 g ha-1 ). The herbicide was applied when the coffee plants reached 21 pairs of leaves, before reaching their upper third ones. At 45 and 120 days after glyphosate application (DAA), increase in leaf area, stem diameter, number of leaves and plagiotropic branches was evaluated, being initially measured on the day the herbicide was applied, and plant intoxication rate at 10, 45 and 120 DAA. Dry matter of leaves, roots and stem, and root length and density were measured at 120 DAA. Symptoms of coffee plant intoxication caused by glyphosate were similar in different cultivars, being characterized by chlorosis and leaf narrowing. Increase in the number of leaves, plagiotropic branches and stem diameter, regardless of the cultivar, was not affected by glyphosate. Cultivar Topázio was the most sensitive to glyphosate, in terms of accumulation of leaf area, root dry matter and root density.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)(FAPEMIG) Fundação de Amparo à Pesquisa do Estado de Minas Gerai

Ametryn leaching on Red-Yellow Latosol and Red-Yellow Ultisol with different pH values

Objetivou-se com este trabalho avaliar o potencial de lixiviação do ametryn num Argissolo Vermelho-Amarelo e num Latossolo Vermelho-Amarelo utilizados com pastagens no Brasil, com diferentes valores de pH. Para isso, foram avaliados 120 tratamentos (quatro solos associados a três intensidades de chuva e 10 profundidades), em parcela subdividida no delineamento inteiramente casualizado, com três repetições. Colunas de PVC de 50 cm de comprimento por 10 cm de diâmetro foram preenchidas com os solos e umedecidas; em seguida, aplicou-se o herbicida e simularam-se chuvas no topo delas, nas intensidades especificadas de acordo com o tratamento. Após 72 horas, todas as colunas foram dispostas na posição horizontal e abertas longitudinalmente, coletando-se amostras dos solos a cada intervalo de 5 cm de profundidade, para posterior extração e quantificação do herbicida e análise por cromatografia líquida de alta eficiência - CLAE. Posteriormente, no restante das amostras de solo, semeou-se ao longo de cada coluna a espécie indicadora Cucumis sativus. Concluiu-se que solos com baixo teor de matéria orgânica e/ou pH mais elevado apresentaram maiores índices de lixiviação do ametryn. Além disso, o método do bioensaio foi mais eficiente na confirmação da lixiviação do ametryn em comparação à CLAE.The objective of this work was to evaluate ametryn leaching potential in soil used for pasture in Brazil (Red-Yellow Latosol (LVA) and Red-Yellow Ultisol (PVA)) with different pH values. Thus, 120 treatments were evaluated (four soils related to three rainfall intensities and 10 soil column depths). The experiments were arranged in a completely randomized design in split-plots and three replications. PVC columns of 10 cm diameter by 50 cm length were filled with the soil samples, moistened and placed upright for 48 hours to drain the excess water. The herbicide was applied and rainfall was simulated on top of the columns at intensities specified according to the treatment. After 72 hours, the columns were opened longitudinally, placed in a horizontal position and soil samples were collected at each 5 cm interval depth for posterior herbicide extraction and quantification by liquid chromatography (HPLC). The remaining soil columns were sown with the indicator species (Cucumis sativus) in the substrate along the opening to evaluate ametryn leaching. After 21days of emergence, evaluations were conducted to verify the intoxication symptoms caused by ametryn in the plants. It was concluded that soils with low organic matter content and/or higher pH showed higher ametryn leaching rates, and that the bioassay method was more efficient in confirming ametryn leaching than liquid chromatography

Validation of the Virtual Reality Everyday Assessment Lab (VR-EAL):An immersive virtual reality neuropsychological battery with enhanced ecological validity

International audienceObjective: The assessment of cognitive functions such as prospective memory, episodic memory, attention, and executive functions benefits from an ecologically valid approach to better understand how performance outcomes generalize to everyday life. Immersive virtual reality (VR) is considered capable of simulating real-life situations to enhance ecological validity. The present study attempted to validate the Virtual Reality Everyday Assessment Lab (VR-EAL), an immersive VR neuropsychological battery, against an extensive paper-andpencil neuropsychological battery. Methods: Forty-one participants (21 females) were recruited: 18 gamers and 23 non-gamers who attended both an immersive VR and a paper-and-pencil testing session. Bayesian Pearson correlation analyses were conducted to assess construct and convergent validity of the VR-EAL. Bayesian t-tests were performed to compare VR and paper-and-pencil testing in terms of administration time, similarity to real life tasks (i.e., ecological validity), and pleasantness. Results: VR-EAL scores were significantly correlated with their equivalent scores on the paper-and-pencil tests. The participants' reports indicated that the VR-EAL tasks were significantly more ecologically valid and pleasant than the paper-and-pencil neuropsychological battery. The VR-EAL battery also had a shorter administration time. Conclusion: The VR-EAL appears as an effective neuropsychological tool for the assessment of everyday cognitive functions, which has enhanced ecological validity, a highly pleasant testing experience, and does not induce cybersickness

Tracking Quintessence and Cold Dark Matter Candidates

We study the generation of a kination-dominated phase in the context of a quintessential model with an inverse-power-law potential and a Hubble-induced mass term for the quintessence field. The presence of kination is associated with an oscillating evolution of the quintessence field and the barotropic index. We find that, in sizeable regions of the parameter space, a tracker scaling solution can be reached sufficiently early to alleviate the coincidence problem. Other observational constraints originating from nucleosynthesis, the inflationary scale, the present acceleration of the universe and the dark-energy-density parameter can be also met. The impact of this modified kination-dominated phase on the thermal abundance of cold dark matter candidates is investigated too. We find that: (i) the enhancement of the relic abundance of the WIMPs with respect to the standard paradigm, crucially depends on the hierarchy between the freeze-out temperature and the temperature at which the extrema in the evolution of the quintessence field are encountered, and (ii) the relic abundance of e-WIMPs takes its present value close to the temperature at which the earliest extremum of the evolution of the quintessence field occurs and, as a consequence, both gravitinos and axinos arise as natural cold dark matter candidates. In the case of unstable gravitinos, the gravitino constraint can be satisfied for values of the initial temperature well above those required in the standard cosmology.Comment: Final versio

Influência de herbicidas na atividade fotossintética de genótipos de cana-de-açúcar

Objetivou-se com este trabalho avaliar em campo os efeitos de herbicidas sobre a atividade fotossintética de genótipos de cana-de-açúcar. Para isso, foi realizado um experimento em blocos casualizados, em parcelas subdivididas, com quatro repetições. Nas parcelas principais alocaram-se os herbicidas ametryn (2.000 g ha-1), trifloxysulfuron-sodium (22,5 g ha 1), a mistura de ametryn + trifloxysulfuron-sodium (1.463 + 37,0 g ha-1) e uma testemunha capinada. Nas subparcelas foram avaliados seis genótipos de cana-de-açúcar (RB72454, RB835486, RB855113, RB867515, RB947520 e SP80-1816). Aos 70 dias após o plantio e 15 dias após a aplicação dos herbicidas, foram realizadas as avaliações da taxa de fluxo de gases pelos estômatos (U - μmol s-1), concentração de CO2 subestomática (Ci = μmol mol-1), taxa fotossintética (A - μmol m 2 s-1) e CO2 consumido (ΔC - μmol mol-1), na primeira folha da cana-de-açúcar com a lígula visível (dewlap visível). O ametryn causou danos significativos nas características fisiológicas ligadas à atividade fotossintética da cana-de-açúcar, em comparação com o trifloxysulfuron-sodium. Os genótipos de cana-de-açúcar apresentam sensibilidade diferencial aos herbicidas. Os mais suscetíveis ao ametryn foram o RB835486 e RB867515, e os mais tolerantes, o RB72454, RB855113, RB947520 e SP80-1816. Quanto às características avaliadas, não se observou diferença entre os genótipos tratados com o trifloxysulfuron-sodium e a mistura de ametryn + trifloxysulfuron-sodium.The objective of this study was to evaluate the effects of herbicides on the photosynthetic activity of sugarcane genotypes, under field conditions. An experiment was arranged in a randomized block design with split-plots and four replications.The following herbicides were allocated in the main plot: ametryn (2.000 g ha-1), trifloxysulfuron-sodium (22.5 g ha-1), mixture of ametryn + trifloxysulfuron-sodium (1,463 + 37 g ha-1) and a hoed treatment without herbicide. In the subplots, six sugarcane genotypes (RB72454, RB835486, RB855113, RB867515, RB947520 and SP80-1816) were allocated. At 70 days after planting and 15 days after herbicide application, evaluations of stomatal gas flow rate (U - μmol s-1), sub-stomatal CO2 concentration (Ci - μmol mol-1) , photosynthetic rate (A - μmol m-2 s-1) and CO2 consumed (ΔC - μmol mol-1) were conducted on the first plant leaf with visible ligule. Ametryn caused significant damage to the physiological characteristics related to sugarcane photosynthetic activity compared to the trifloxysulfuron-sodium. Sugarcane genotypes show differential sensitivity to herbicide treatments, with the most susceptible to ametryn being RB835486 and RB867515, and the most tolerant RB72454, RB855113, RB947520, SP80-1816 and RB867515. Regarding the evaluated characteristics, there was no difference between the genotypes treated with trifloxysulfuron- sodium and the mixture of ametryn + trifloxysulfuron-sodium

On exact solutions for quintessential (inflationary) cosmological models with exponential potentials

We first study dark energy models with a minimally-coupled scalar field and exponential potentials, admitting exact solutions for the cosmological equations: actually, it turns out that for this class of potentials the Einstein field equations exhibit alternative Lagrangians, and are completely integrable and separable (i.e. it is possible to integrate the system analytically, at least by quadratures). We analyze such solutions, especially discussing when they are compatible with a late time quintessential expansion of the universe. As a further issue, we discuss how such quintessential scalar fields can be connected to the inflationary phase, building up, for this class of potentials, a quintessential inflationary scenario: actually, it turns out that the transition from inflation toward late-time exponential quintessential tail admits a kination period, which is an indispensable ingredient of this kind of theoretical models. All such considerations have also been done by including radiation into the model.Comment: Revtex4, 10 figure

Dark Energy from structure: a status report

The effective evolution of an inhomogeneous universe model in any theory of gravitation may be described in terms of spatially averaged variables. In Einstein's theory, restricting attention to scalar variables, this evolution can be modeled by solutions of a set of Friedmann equations for an effective volume scale factor, with matter and backreaction source terms. The latter can be represented by an effective scalar field (`morphon field') modeling Dark Energy. The present work provides an overview over the Dark Energy debate in connection with the impact of inhomogeneities, and formulates strategies for a comprehensive quantitative evaluation of backreaction effects both in theoretical and observational cosmology. We recall the basic steps of a description of backreaction effects in relativistic cosmology that lead to refurnishing the standard cosmological equations, but also lay down a number of challenges and unresolved issues in connection with their observational interpretation. The present status of this subject is intermediate: we have a good qualitative understanding of backreaction effects pointing to a global instability of the standard model of cosmology; exact solutions and perturbative results modeling this instability lie in the right sector to explain Dark Energy from inhomogeneities. It is fair to say that, even if backreaction effects turn out to be less important than anticipated by some researchers, the concordance high-precision cosmology, the architecture of current N-body simulations, as well as standard perturbative approaches may all fall short in correctly describing the Late Universe.Comment: Invited Review for a special Gen. Rel. Grav. issue on Dark Energy, 59 pages, 2 figures; matches published versio