Papers by Juan Manuel Gomez Novoa
Yo, Juan Carlos Guaján Novoa en calidad del autor del trabajo de grado o tesis realizada sobre: "... more Yo, Juan Carlos Guaján Novoa en calidad del autor del trabajo de grado o tesis realizada sobre: "Periódico Comunitario Nuestra Tierra Nayón 2013" Propuesta de Comunicación Popular, por la presenta autorizo a la UNIVERSIDAD CENTRAL DEL ECUADOR, hacer uso de todos los contenidos que me pertenecen o parte de los contenidos de los que contiene esta obra, con fines estrictamente académicos o de investigación. Los derechos que como autor me corresponden, con excepción de la presente autorización, seguirán vigentes a mi favor, de conformidad con lo establecido en los artículos 5,
Revista Cubana De Cardiologia Y Cirugia Cardiovascular, Oct 22, 2012
Se trata de una paciente de 25 años de edad, con antecedentes de hipertensión arterial sistémica ... more Se trata de una paciente de 25 años de edad, con antecedentes de hipertensión arterial sistémica desde la edad de 17 años. En el examen físico esta paciente presentaba pulsos femorales y tibiales posteriores aunque eran estos ligeramente tardíos, a la auscultación se halló un soplo sistólico eyectivo aórtico III/ VI sin llegar a ser interescapular. Sospechamos la coartación aórtica y decidimos realizar una angiotomografía aórtica que nos permitió hacer el diagnóstico definitivo de una coartación aórtica apretada circunscrita con aneurima gigante postcoartación.
América sin Nombre, 2008
Estudio que trata de circunscribir la figura de Elena en la relación con sus contemporáneos, con ... more Estudio que trata de circunscribir la figura de Elena en la relación con sus contemporáneos, con los que coincide en la actitud rebelde e iconoclasta. El sentido documental de la literatura aporta una nueva faceta a la escritura de México.
Revista Cubana De Cardiologia Y Cirugia Cardiovascular, Oct 15, 2014
Cierre percutáneo con dispositivo Amplatzer de persistencia delductus arterioso gigante en gestante.
Revista cubana de pediatría
La estenosis pulmonar valvular crítica es una cardiopatía congénita relativamente frecuente en el... more La estenosis pulmonar valvular crítica es una cardiopatía congénita relativamente frecuente en el recién nacido, cuya supervivencia depende de una intervención inmediata, ya sea farmacológica o quirúrgica. Su diagnóstico prenatal ha permitido tratarla in útero mediante dilatación de la válvula por angioplastia con balón. Esta técnica conlleva los riesgos inherentes a todo proceder que implique el acceso al feto. Está demostrado que con la angioplastia posnatal precozmente diagnosticada mediante ecocardiografía, se pueden obtener resultados igualmente satisfactorios, previa estabilización clínica y hemodinámica del paciente. Apostamos, pues, por esta última. Palabras clave: estenosis pulmonar crítica, ecocardiografía fetal, angioplastia con balón, intervencionismo fetal, diagnóstico prenatal, cardiopatías congénitas. SUMMARY Critical valvular pulmonary stenosis is a relatively frequent congenital cardiopathy in the newborn, whose survival depends on an immediate intervention either pharmacological or surgical. The prenatal diagnosis allows the intrauterine treatment by dilating the valve through the ball angioplasty. This technique carries the risks inherent to any procedures involving access to the fetus. It has been proved that postnatal angioplasty, early diagnosed with echography, can obtain the same satisfactory results, after the clinical
La estenosis valv aórtica con balón por fallo biventric nes del tratamien
Phys. Chem. Chem. Phys., 2014
S1-Model Systems and Unit Cell parameters for 1a-1h. The initial (crystal structures reported in ... more S1-Model Systems and Unit Cell parameters for 1a-1h. The initial (crystal structures reported in the literature) and final (optimized) lattice parameters of the super-cells are collected in Table S1. For the distorted super-cells (1a, 1c, 1e and 1g) the crystalline unit cells, which contained 4 SCO units and 8 counterions, were directly adopted as initial structure. For the regular ones (1b, 1d, 1f and 1h), the unit cells, which contained 2 SCO units and 4 counterions, were doubled in order to include the same number of
Multistep π dimerization of tetrakis(n-decyl)heptathienoacene radical cations: a combined experimental and theoretical study
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 11, 2014
Radical cations of a heptathienoacene α,β-substituted with four n-decyl side groups (D4T7(.) (+) ... more Radical cations of a heptathienoacene α,β-substituted with four n-decyl side groups (D4T7(.) (+) ) form exceptionally stable π-dimer dications already at ambient temperature (Chem. Comm. 2011, 47, 12622). This extraordinary π-dimerization process is investigated here with a focus on the ultimate [D4T7(.) (+) ]2 π-dimer dication and yet-unreported transitory species formed during and after the oxidation. To this end, we use a joint experimental and theoretical approach that combines cyclic voltammetry, in situ spectrochemistry and spectroelectrochemistry, EPR spectroscopy, and DFT calculations. The impact of temperature, thienoacene concentration, and the nature and concentration of counteranions on the π-dimerization process is also investigated in detail. Two different transitory species were detected in the course of the one-electron oxidation: 1) a different transient conformation of the ultimate [D4T7(.) (+) ]2 π-dimer dications, the stability of which is strongly affected by th...
Theoretical Chemistry Accounts, 2013
This issue of Theoretical Chemistry Accounts contains a recollection of some of the work presente... more This issue of Theoretical Chemistry Accounts contains a recollection of some of the work presented and discussed at the 8th edition of the Electronic Structure: Principles and Applications (in short, ESPA-2012). The ESPA events are biennial international research conferences organized within the activities of the Spanish Theoretical Chemistry groups that co-organize the Interuniversity Doctorate in Theoretical Chemistry and Computational Modeling. The main aim behind all ESPA conferences, shared by the organizers of ESPA-2012, is promoting scientific excellence and exchange of ideas among their Ph. D. students, in a friendly environment. ESPA-2012 follows previous events held in Madrid,
The Journal of Physical Chemistry B, 2001
The origin of the bistability in the thiazyl radical 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA): A first principles bottom-up investigation of the magnetic properties of its high temperature polymorph
Polyhedron, 2009
A first principles bottom-up study is performed on the high temperature polymorph of the thiazyl ... more A first principles bottom-up study is performed on the high temperature polymorph of the thiazyl radical 1,3,5-trithia-2,4,6-triazapentalenyl, TTTA, a purely organic molecule-based magnet that shows thermal bistability, with the aim of getting a quantitative understanding at the molecular level the mechanism of thermal bistability and the factors that control the existence of a hysteresis loop. Experimental studies on crystals of
Physical Review Letters, 1997
Magnetization, heat capacity, and neutron diffraction experiments on the b-phase of the dithiadia... more Magnetization, heat capacity, and neutron diffraction experiments on the b-phase of the dithiadiazolyl radical, p-NC.C 6 F 4 .CNSSN. , provide conclusive evidence that this system exhibits noncollinear antiferromagnetism at 35.5 K, an unprecedented temperature for an organic radical. On the basis of magnetization and powder neutron diffraction results, coupled with theoretical calculations of the spin distribution within the molecule, a magnetic structure for this compound is proposed in which the interactions propagate through S. .. N contacts. [S0031-9007(97)04066-0]
Ab Initio Computation of the Spin Population of Substituted α-Nitronyl Nitroxide Radicals
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1995
Abstract The ability of various ab initio methods (UHF, ROHF, MCSCF, MP2, CISD, CCD) to reproduce... more Abstract The ability of various ab initio methods (UHF, ROHF, MCSCF, MP2, CISD, CCD) to reproduce the experimental information on the spin distribution over various substituted α-nitronyl nitroxide radicals was tested using various basis sets which range from single ...
Journal of the American Chemical Society, 2009
Figure S1. Two-dimensional view of the total density of the phenalenyl dimer, done and along the ... more Figure S1. Two-dimensional view of the total density of the phenalenyl dimer, done and along the plane that contains the central C atoms of both phanelenyl fragments (atoms C1 and C2, the central atoms in the top and lower rows in the figure) and atoms C9, C10, C21 and C22 (the four lateral atoms). See Table 6 for the atom numbering scheme. The existence of the C1-C2, C9-CC22, and C10-C21 bonds is clearly shown. The location of the bond critical point that links atoms C1 and C2 is marked by a red dot.
Generalized Stone-Wales transformation as the possible origin of ferromagnetism in polymeric C[sub 60]: A density-functional theory study
The Journal of Chemical Physics, 2006
Recently, there has been a proposal [Y.-H. Kim et al., Phys. Rev. B 68, 125420 (2003)] suggesting... more Recently, there has been a proposal [Y.-H. Kim et al., Phys. Rev. B 68, 125420 (2003)] suggesting that ferromagnetic interactions in compressed and heated polymeric-C(60) solids could be due to the existence of triplet open cages resulting from successive generalized Stone-Wales transformations within the C(60) cage. Here, by performing B3LYP3-21G and B3LYP6-31G(d) optimizations, we carried out a systematic investigation of the thermodynamics and kinetics of the mechanism of generation of these open cages in their closed-shell singlet, open-shell singlet, and triplet states. We also computed the magnetic interactions induced by the open cages presenting a triplet ground state. Our results indicate that this mechanism is not appropriate to explain the ferromagnetism found in compressed and heated polymeric C(60) for the following reasons: (a) the formation of the only open cage presenting a triplet ground state requires overpassing a highest energy point of 318 kcal/mol, well above other competitive mechanisms reported in the literature; the triplet open cages formed are not stable against their transformation into a diamagnetic intermediate; (c) the magnetic interactions between two adjacent triplet open cages are antiferromagnetic.
Interactions energies associated with short intermolecular contacts of C–H bonds. II. Ab initio computational study of the C–H⋅⋅⋅H–C interactions in methane dimer
The Journal of Chemical Physics, 1991
Interactions energies associated with short intermolecular contacts of CH bonds. II. Ab initio c... more Interactions energies associated with short intermolecular contacts of CH bonds. II. Ab initio computational study of the CH⋅⋅⋅HC interactions in methane dimer. [The Journal of Chemical Physics 94, 4835 (1991)]. Juan J. Novoa, Myung-Hwan Whangbo, Jack M. Williams. ...
International Journal of Quantum Chemistry, 2001
The dimers of dicoordinated Cu(I) complexes of the type [CuXL], where X − = Cl − , Br − , I − , o... more The dimers of dicoordinated Cu(I) complexes of the type [CuXL], where X − = Cl − , Br − , I − , or CN − and L is a neutral ligand such as NH 3 , PH 3 , or CNCH 3 , have been studied by means of ab initio and density functional calculations. The performance of density functional calculations using the hybrid B3LYP method has been compared with MP2 results. Ligand and conformational effects are analyzed for two types of dimers, notably those in which the monomers retain their linear conformation and associate through Cu-Cu contacts and those in which the X ligands act as bridges resulting in tricoordination of each Cu atom and a rhombic Cu 2 X 2 core.
Inorganic Chemistry, 2009
H x K 1-x M II [Ru 2 (CO 3) 4 ](H 2 O) y (MeOH) z (M = Mn, Fe, Co, Ni, Mg) were synthesized from ... more H x K 1-x M II [Ru 2 (CO 3) 4 ](H 2 O) y (MeOH) z (M = Mn, Fe, Co, Ni, Mg) were synthesized from the reaction of M II and K 3 [Ru 2 (CO 3) 4 ] in water and are isomorphous with an orthorhombic three-dimensional network structures based on μ 3-CO 3 2linkages to Ru 2 moieties forming layers and also to trans-M II (OH 2) 4 sites forming linked chains that connect the layers. They, as well as nonisomorphous M = Cu, magnetically order as canted ferrimagnets with T c = 4.4 (1.0 K. The presence of S = 0 M II = Mg(II) has essentially no effect on T c suggesting that the main magnetic pathway does not occur the through M II-based chains, but only via Ru 2 3 3 3 Ru 2 linkages that reside in layers. This is a rare example of a magnet based upon a second row transition metal.
Inorganic Chemistry, 2007
European Journal of Inorganic Chemistry, 2008
The family of charge-transfer (CT) salts [M(Cp*) 2 ][Ni(α-tpdt) 2 ] [α-tpdt = 2,3-thiophenedithio... more The family of charge-transfer (CT) salts [M(Cp*) 2 ][Ni(α-tpdt) 2 ] [α-tpdt = 2,3-thiophenedithiolate; M = Fe (1), Mn (2), Cr (3)] were prepared. The crystal structure of 3 is similar to that previously reported for 1 and is composed of alternating layers each consisting of parallel mixed donor-acceptor D + AD + AD + Achains, and the chains in adjacent layers are perpendicular. A similar crystal structure is expected to occur in 2. The McConnell I model was used to analyze the intermolecular magnetic coupling in this family of compounds. The predicted ferromagnetic (FM) intrachain coupling and the antiferromagnetic (AFM) coupling in the interchain coupling (both intra and interlayer) are in good agreement
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Papers by Juan Manuel Gomez Novoa