636 research outputs found

    A new species of \u3cem\u3eAnanteris\u3c/em\u3e (Scorpiones: Buthidae) from Panama

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    A new buthid species belonging to the genus Ananteris Thorell, 1891 is herein described from Panama Oeste Province, Panama. This is the second Ananteris species known from this Central American country and clearly differs from Ananteris platnicki Lourenço, 1993, distributed in Costa Rica and Panama, by its smaller size and male having a different hemispermatophore and telson similar to that of the female

    Theoretical study of the photoconduction and photomagnetism of the BPY[Ni(dmit)2]2 molecular crystal

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    The BPY[Ni(dmit)2]2 molecular crystal synthesized by Naito and coworkers (J. Am. Chem. Soc., 2012, 134, 18656) was characterized as a photo-magnetic-conductor. This crystal is a nonmagnetic semiconductor in the dark and becomes a magnetic conductor after UV irradiation. This work analyzes the key ingredients of the observed photomagnetism and photoconduction by means of wavefunction-based calculations on selected fragments and periodic calculations on the whole crystal. Our results demonstrate that UV-Vis light induces charge transfer processes between the closest [Ni(dmit)2]− and BPY2+ units, that introduce unpaired electrons on the unoccupied orbitals of the BPY cations. Since the conduction bands present a strong mixing of BPY and Ni(dmit)2, the optically activated anion–cation charge transfer enhances the conductivity. The photoinduced (BPY2+)* radicals can indeed interact with the close Ni(dmit)2 units, with non-negligible spin–spin magnetic couplings, which are responsible for the changes induced by the irradiation on the temperature dependence of the magnetic susceptibility.Ministerio de Economía y Competitividad de España y fondos FEDER. CTQ-2015-69019-

    Profilaxis de los puentes óseos fisarios mediante interposición de injerto autólogo de periostio. Estudio experimental en conejos

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    Se ha realizado un trabajo experimental sobre la profilaxis de los puentes óseos epifisometafisarios mediante la interposición de injerto autólogo de periostio, planteando los siguientes objetivos: 1) Conseguir una barrera epifisometafisaria que impida la comunicación de los vasos epifisarios y metafisarios y 2) Estudiar la capacidad condrogénica del periostio. Se han utilizado 48 conejos, distribuidos en dos Series de cuatro Grupos cada una, según el momento del sacrificio a la 1a, 2a, 4a y 8a semanas. En la serie Control, se procedió a la extirpación de 1/3 de la fisis distal externa, mientras que en la Experimental se interpuso un injerto Ubre de periostio. Todos los especímenes se estudiaron macroscópica, radiológica e histológicamente. Las conclusiones han sido, que el periostio como injerto Ubre: 1) Actúa como barrera pasiva en las lesiones fisarias en las primeras semanas. 2) Tiene capacidad condrogénica en las primeras semanas. 3) A largo plazo no es un material efectivo en la profilaxis de los puentes óseos epífiso-metafisarios.An experimental work has been carried out on prevention of fiseal bone bridges formation by means of interposing autologus periosteum graft, bringing up the following objetives: 1) To achieve a barrier which can prevent the communication between epiphyseal and metaphyseal vessels, and 2) To study the condrogenic potencial of periosteum. A total of 48 rabbits have been used, arranged in three series of four groups each, acording to the moment of sacrifice in the 1st, 2nd, 4th and 8 t h weeks. They were all operated on the right femur. In the control serie an extirpation of 1/3 of the outer and distal growth plate was carried out, while in the experimental series the created defect was filled up with a free periosteum graft. All the specimens were studied macroscopically, radiologically and histologically. As conclusions, the periosteum used as a free graft: 1) In the first weeks act like a pasive barrier in physeal lesions, 2) It has also condrogenic capacity in the first weeks and, 3) On large follow-up studies, the periosteum do not seems to be a efective material to prevent physeal bone bridges

    Electronic Descriptors for Supervised Spectroscopic Predictions

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    Spectroscopic properties of molecules holds great importance for the description of the molecular response under the effect of an UV/Vis electromagnetic radiation. Computationally expensive ab initio (e.g. MultiConfigurational SCF, Coupled Cluster) or TDDFT methods are commonly used by the quantum chemistry community to compute these properties. In this work, we propose a (supervised) Machine Learning approach to model the absorption spectra of organic molecules. Several supervised ML methods have been tested such as Kernel Ridge Regression (KRR), Multiperceptron Neural Networs (MLP) and Convolutional Neural Networks. The use of only geometrical descriptors (e.g. Coulomb Matrix) proved to be insufficient for an accurate training. Inspired on the TDDFT theory, we propose to use a set of electronic descriptors obtained from low-cost DFT methods: orbital energy differences, transition dipole moment between occupied and unoccupied Kohn-Sham orbitals and charge-transfer character of mono-excitations. We demonstrate that with this electronic descriptors and the use of Neural Networks we can predict not only a density of excited states, but also getting very good estimation of the absorption spectrum and charge-transfer character of the electronic excited states, reaching results close to the chemical accuracy (~2 kcal/mol or ~0.1eV)

    Reparación del cartílago articular con injerto libre de pericondrio estudio experimental

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    Ante la incapacidad de regeneración espontánea de lesiones profundas y amplias del cartílago articular, estudiamos la reparación cartilaginosa con plastias de pericondrio tomadas de la región condro-costal e implantándolas con su cara condrogénica sobre una lesión osteocondral realizada en la superficie articular rotuliana. Macroscópica e histológicamente, a la octava semana, el neocartílago formado tenía igual apariencia que el cartílago hialino normal, no existiendo separación entre el cartílago remanente y el neoformado a partir de la plastia. Estos resultados corroboran el gran potencial condrogénico del pericondrioFaced with the incapacity of spontaneous regeneration of deep and extensive lesions of the articular cartilage we studied the cartilaginous repair with pericondrium grafts taken from the chondro-costal region. Grafts were implanted with their condrogenic face over an osteochondral defect located at the surface of the patella. At the 8th week, the neocartilage formed had macroscopically and histologically, the same appearance as the normal hyaline cartilage, with no separation between the remaining cartilage and the neocartilage induced by the graft. These results corroborate the high chondrogenic potential of the perichondrium

    A basic electro-topological descriptor for the prediction of organic molecule geometries by simple machine learning

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    This paper proposes a machine learning (ML) method to predict stable molecular geometries from their chemical composition. The method is useful for generating molecular conformations which may serve as initial geometries for saving time during expensive structure optimizations by quantum mechanical calculations of large molecules. Conformations are found by predicting the local arrangement around each atom in the molecule after trained from a database of previously optimized small molecules. It works by dividing each molecule in the database into minimal building blocks of different type. The algorithm is then trained to predict bond lengths and angles for each type of building block using an electro-topological fingerprint as descriptor. A conformation is then generated by joining the predicted blocks. Our model is able to give promising results for optimized molecular geometries from the basic knowledge of the chemical formula and connectivity. The method trends to reproduce interatomic distances within test blocks with RMSD under 0.05

    Update on Dihydropteroate Synthase (DHPS) Mutations in Pneumocystis jirovecii

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    A Pneumocystis jirovecii is one of the most important microorganisms that cause pneumonia in immunosupressed individuals. The guideline for treatment and prophylaxis of Pneumocystis pneumonia (PcP) is the use of a combination of sulfa drug-containing trimethroprim and sulfamethoxazole. In the absence of a reliable method to culture Pneumocystis, molecular techniques have been developed to detect mutations in the dihydropteroate synthase gene, the target of sulfa drugs, where mutations are related to sulfa resistance in other microorganisms. The presence of dihydropteroate synthase (DHPS) mutations has been described at codon 55 and 57 and found almost around the world. In the current work, we analyzed the most common methods to identify these mutations, their geographical distribution around the world, and their clinical implications. In addition, we describe new emerging DHPS mutations. Other aspects, such as the possibility of transmitting Pneumocystis mutated organisms between susceptible patients is also described, as well as a brief summary of approaches to study these mutations in a heterologous expression system

    Pneumocystis jirovecii and microsporidia: An unusual coinfection in HIV patients?

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    Pneumocystis jirovecii and microsporidia species are recognized as opportunistic infectious pathogens in AIDS patients. Coinfection of both in one patient has been rarely reported. The aim of the present study was to investigate the coinfection of P. jirovecii and microsporidia in different tissues from AIDS deceased patients. Post mortem histological finding of P. jirovecii and microsporidia was demonstrated by means of the Grocott’smethenamine silver and Brown Brenn staining, respectively. Molecular technique was used for identification and characterization of both fungi. Out of the 514 autopsied cases P. jirovecii andmicrosporidia species were identified in 53 (10.3%) and 62 (12.1%) cases respectively. A total of five cases (0.97%) coinfected with Pneumocystis and microsporidia were recovered from all analyzed autopsies. Coinfection of Pneumocystis and microsporidia is very challenging and raises interesting issues about host-parasite relationship. The early diagnosis of both pathogens must be crucial to establish correct and early treatments, improve the patient’s evolution, reducing the risk of death
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