Analysis of the tautomeric equilibrium of two red monoazo dyes by UV–Visible, Raman and SERS spectroscopies

Acid Red 26 and Acid Red 18 are two early synthetic dyes belonging to the monazo dye class. The molecular structure of this class of dyes is characterized by the chromophoric azo group (N[dbnd]N) generally attached to benzene or naphthalene derivatives containing electron withdrawing and/or donating groups as substituents. As both red dyes have an OH group in ortho- position respect to the azo group, they undergo an azo-hydrazone tautomerism. In this work, UV–Vis, Raman and SERS spectroscopic analysis of the red dye solutions were carried out at different pH conditions, in order to evaluate the preponderance of one tautomer over the other as a function of the pH. Different experimental conditions were tested in order to find the best ones for the detection of both dyes. Thus, Raman spectra of the powder and aqueous solutions of AR26 and AR18 were obtained at the natural pH of the solutions, and above and below that value. The SERS analysis of the dye solutions were carried out at various pH values between 2 and 10, and with excitation at 442, 532 and 633 nm. The molecular structure and the theoretical Raman spectra of the two tautomers of both red dyes were calculated by DFT methods. The obtained results were used for the assignment of the Acid Red 26 and Acid Red 18 vibrational modes. Finally, a textile sample dyed with AR18 was analyzed by SERS

The CARMENES search for exoplanets around M dwarfs - Photospheric parameters of target stars from high-resolution spectroscopy

The new CARMENES instrument comprises two high-resolution and high-stability spectrographs that are used to search for habitable planets around M dwarfs in the visible and near-infrared regime via the Doppler technique. Characterising our target sample is important for constraining the physical properties of any planetary systems that are detected. The aim of this paper is to determine the fundamental stellar parameters of the CARMENES M-dwarf target sample from high-resolution spectra observed with CARMENES. We also include several M-dwarf spectra observed with other high-resolution spectrographs, that is CAFE, FEROS, and HRS, for completeness. We used a {chi}^2 method to derive the stellar parameters effective temperature T_eff, surface gravity log g, and metallicity [Fe/H] of the target stars by fitting the most recent version of the PHOENIX-ACES models to high-resolution spectroscopic data. These stellar atmosphere models incorporate a new equation of state to describe spectral features of low-temperature stellar atmospheres. Since T_eff, log g, and [Fe/H] show degeneracies, the surface gravity is determined independently using stellar evolutionary models. We derive the stellar parameters for a total of 300 stars. The fits achieve very good agreement between the PHOENIX models and observed spectra. We estimate that our method provides parameters with uncertainties of {sigma} T_eff = 51 K, {sigma} log g = 0.07, and {sigma} [Fe/H] = 0.16, and show that atmosphere models for low-mass stars have significantly improved in the last years. Our work also provides an independent test of the new PHOENIX-ACES models, and a comparison for other methods using low-resolution spectra. In particular, our effective temperatures agree well with literature values, while metallicities determined with our method exhibit a larger spread when compared to literature results

ATRA mechanically reprograms pancreatic stellate cells to suppress matrix remodelling and inhibit cancer cell invasion

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a dismal survival rate. Persistent activation of pancreatic stellate cells (PSCs) can perturb the biomechanical homoeostasis of the tumour microenvironment to favour cancer cell invasion. Here we report that ATRA, an active metabolite of vitamin A, restores mechanical quiescence in PSCs via a mechanism involving a retinoic acid receptor beta (RAR-β)-dependent downregulation of actomyosin (MLC-2) contractility. We show that ATRA reduces the ability of PSCs to generate high traction forces and adapt to extracellular mechanical cues (mechanosensing), as well as suppresses force-mediated extracellular matrix remodelling to inhibit local cancer cell invasion in 3D organotypic models. Our findings implicate a RAR-β/MLC-2 pathway in peritumoural stromal remodelling and mechanosensory-driven activation of PSCs, and further suggest that mechanical reprogramming of PSCs with retinoic acid derivatives might be a viable alternative to stromal ablation strategies for the treatment of PDAC

Instantons in the Double-Tensor Multiplet

The double-tensor multiplet naturally appears in type IIB superstring compactifications on Calabi-Yau threefolds, and is dual to the universal hypermultiplet. We revisit the calculation of instanton corrections to the low-energy effective action, in the supergravity approximation. We derive a Bogomolny'i bound for the double-tensor multiplet and find new instanton solutions saturating the bound. They are characterized by the topological charges and the asymptotic values of the scalar fields in the double-tensor multiplet.Comment: 17 pages, LaTeX2e with amsmath.sty; v2: minor change

Redução da severidade da brusone foliar em arroz por Sarocladium oryzae.

O objetivo do trabalho foi avaliar, em casa de vegetação, o potencial de Sarocladium oryzae na redução da severidade da brusone nas folhas de arroz. O isolado de S. oryzae, Sa03, da coleção de fungos e microrganismos multifuncionais da Embrapa Arroz e Feijão (CFMMCNPAF) foi cultivado em meio de cultura líquido (Omura, 1976) para a obtenção do filtrado e em BDA para obtenção de esporos

Detecção morfológica, patogênica e molecular de Curtobacterium flaccumfaciens pv. flaccumfaciensem feijoeiro comum.

A murcha-de-curtobacterium do feijoeiro causada por Curtobacterium flaccumfacienspv. flaccumfaciens (Cff), foi descrita em 1926, nos Estados Unidos e, no Brasil em 1995. Atualmente é encontrada nos estados de São Paulo, Paraná, Santa Catarina, Goiás, Distrito Federal e Mato Grosso do Sul. Por colonizar o xilema, os sintomas na planta infectada variam de flacidez e murcha das plantas ao encarquilhamento, queima do bordo das folhas, e até a morte da planta, podendo causar perdas de até 90% da produção. Com o objetivo de comparar os métodos para detecção de Cff, sete isolados bacterianos foram submetidos aos testes de detecção morfológica, patogênica e molecular.Apresentação oral - graduação

Inibição do desenvolvimento micelial de Magnaporthe oryzae por metabólito extracelular produzido por Sarocladium oryzae.

O trabalho teve como objetivo caracterizar o agente responsável pelo efeito antagônico entre isolados de Sarocladium oryzae e de Magnaporthe oryzae, avaliando a ação do metabólito extracelular produzido pelo primeiro sobre o desenvolvimento micelial do segundo

Estudo da viabilidade de isolados de Sarocladium oryzae e Magnaporthe oryzae oriundos da Coleção de Fitopatógenos da Embrapa Arroz e Feijão.

O presente trabalho objetivou avaliar a viabilidade dos isolados de So armazenados ao longo de quatro anos e isolados de Py armazenados a mais de três décadas em métodos específicos de conservação

Generalization properties of finite size polynomial Support Vector Machines

The learning properties of finite size polynomial Support Vector Machines are analyzed in the case of realizable classification tasks. The normalization of the high order features acts as a squeezing factor, introducing a strong anisotropy in the patterns distribution in feature space. As a function of the training set size, the corresponding generalization error presents a crossover, more or less abrupt depending on the distribution's anisotropy and on the task to be learned, between a fast-decreasing and a slowly decreasing regime. This behaviour corresponds to the stepwise decrease found by Dietrich et al.[Phys. Rev. Lett. 82 (1999) 2975-2978] in the thermodynamic limit. The theoretical results are in excellent agreement with the numerical simulations.Comment: 12 pages, 7 figure