Genetic complementation analysis in Pycnoporus cinnabarinus

White-rot basidiomycetes are known as very powerful degraders of wood components. The relative enzyme activities during the degrading process may vary between different species

Screening for lignin peroxidase genes in natural isolates of white rot fungi

To find lingin peroxidase genes similar to those of Phanerochaete chrysosporium, we have studied several species of white rot fungi collected in nature. The methodology has been DNA hybridization techniques using two synthetic oligonucleotides with a sequence that corresponds to a fragment of the H8 lignin peroxidase gene from P. chrysosporium (Schalch et al. 1989. Mol. Cell. Biol. 9:2743-2747) controlling the structure of the predominant form of the enzyme in this fungus

A method for the preparation of intact chromosomal DNA of Pycnoporus cinnabarinus

We describe an improved procedure to obtain chromosomal DNA of Pycnoporus cinnabarinus, which was used in pulse field gel electrophoresis employing a contour-clamped homogenous electric field (CHEF). Four bands of chromosomal DNA were separated. The procedure may be useful to study the genome of other filamentous fungi

Presence of double stranded RNA in natural isolates of Pycnoporus cinnabarinus

While studying the nucleic acids of different strains of P. cinnabarinus (Pc58, Pc470.3, Pc470.6), the presence of dsRNA molecules (1.7 kb to 3.6 kb) was detected in two of them

Quantum spin transistor with a Heisenberg spin chain

We propose and analyze a scheme for conditional state transfer in a Heisenberg $XXZ$ spin chain which realizes a quantum spin transistor. In our scheme, the absence or presence of a control spin excitation in the central gate part of the spin chain results in either perfect transfer of an arbitrary state of a target spin between the weakly coupled input and output ports, or its complete blockade at the input port. We also present a possible realization of the corresponding spin chain with a one-dimensional ensemble of cold atoms with strong contact interactions.Comment: 36 pages, 3 figures, including supplements. See journal reference below for refereed and revised versio

Clasificador multiclase con redes neuronales convolucionales

El área de reconocimiento de imágenes ha cobrado considerable interés en los últimos años. Este trabajo explora arquitectura de redes neuronales para conseguir un modelo capaz de reconocer un conjunto variado de 30 especies de animales en su hábitat natural. Para cumplir el objetivo, se utilizaron técnicas de Transfer Learning y Fine Tuning para adaptar redes neuronales ampliamente usadas que han demostrado ser eficaces y eficientes, tales como VGG-16, ResNet50 e InceptionV3. Previamente, se procesaron las imágenes de un dataset, reduciendo su tamaño y extrayendo la región de interés. Asimismo, se implementaron técnicas para evitar el overfitting como data augmentation, early stopping, decay, reduceLROnPlateau y oversampling. Los resultados obtenidos fueron satisfactorios, tanto en métricas de error y precisión, como en F1-Score y ROC-AUC, alcanzando valores muy cercanos a 1. Una vez alcanzados estos resultados se realizó un análisis para comprender los puntos débiles de los modelos obtenidos, utilizando t-SNE y matrices de confusión. Como conclusión, los principales errores se encuentran entre especies de animales muy similares en formas, tamaños, hábitat, colores y texturas que incluso para un humano sería difícil diferenciar.Sociedad Argentina de Informática e Investigación Operativ

Evolution of Linear Absorption and Nonlinear Optical Properties in V-Shaped Ruthenium(II)-Based Chromophores

In this article, we describe a series of complexes with electron-rich cis-{Ru^(II)(NH_3)_4}^(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845−4859). They have been isolated as their PF_6− salts and characterized by using various techniques including ^1H NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru^(III/II) waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities β have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d → π^* metal-to-ligand charge-transfer (MLCT) and π → π^* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant β_0 responses as high as ca. 600 × 10^(−30) esu. These pseudo-C_(2v) chromophores show two substantial components of the β tensor, β_(zzz) and β_(zyy), although the relative significance of these varies with the physical method applied. According to HRS, β_(zzz) dominates in all cases, whereas the Stark analyses indicate that β_(zyy) is dominant in the shorter chromophores, but β_(zzz) and β_(zyy) are similar for the extended species. In contrast, finite field calculations predict that β_(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand π-systems are extended. Such unusual behavior has also been observed with related 1D complexes (Coe, B. J. et al. J. Am. Chem. Soc. 2004, 126, 3880−3891)

Diquat Derivatives: Highly Active, Two-Dimensional Nonlinear Optical Chromophores with Potential Redox Switchability

In this article, we present a detailed study of structure−activity relationships in diquaternized 2,2′-bipyridyl (diquat) derivatives. Sixteen new chromophores have been synthesized, with variations in the amino electron donor substituents, π-conjugated bridge, and alkyl diquaternizing unit. Our aim is to combine very large, two-dimensional (2D) quadratic nonlinear optical (NLO) responses with reversible redox chemistry. The chromophores have been characterized as their PF_6^− salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Their visible absorption spectra are dominated by intense π → π^* intramolecular charge-transfer (ICT) bands, and all show two reversible diquat-based reductions. First hyperpolarizabilities β have been measured by using hyper-Rayleigh scattering with an 800 nm laser, and Stark spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities β_0. The directly and indirectly derived β values are large and increase with the extent of π-conjugation and electron donor strength. Extending the quaternizing alkyl linkage always increases the ICT energy and decreases the E_(1/2) values for diquat reduction, but a compensating increase in the ICT intensity prevents significant decreases in Stark-based β_0 responses. Nine single-crystal X-ray structures have also been obtained. Time-dependent density functional theory clarifies the molecular electronic/optical properties, and finite field calculations agree with polarized HRS data in that the NLO responses of the disubstituted species are dominated by ‘off-diagonal’ β_(zyy) components. The most significant findings of these studies are: (i) β_0 values as much as 6 times that of the chromophore in the technologically important material (E)-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate; (ii) reversible electrochemistry that offers potential for redox-switching of optical properties over multiple states; (iii) strongly 2D NLO responses that may be exploited for novel practical applications; (iv) a new polar material, suitable for bulk NLO behavior