C.A. Ponce

National University of the Northeast

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Mario R. Estrada

Food and Agriculture Organization of the United Nations

R. Casali

Istituto Nazionale di Fisica Nucleare, Sezione di Pisa

Francisco Tomás Vert

Universitat de València

M. Caravaca

National University of the Northeast

Juana J. Silber

National University of Río Cuarto

Graciela N. Zamarbide

National University of San Luis

Joaquín O. Singh

National University of Río Cuarto

Juan C. Garro

National University of San Luis

Francisco Tomás-Vert

Universitat de València

Sergio L. Vargas

University of Chile

Cooperative Institutions

University of the Andes

National University of San Luis

Universidad de Los Andes

Universitat de València

University of Chile

Harvard University

Universidad de Los Andes

National University of the Northeast

Consejo Nacional de Investigaciones Científicas y Técnicas

Boston Children's Hospital

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Conformational equilibrium and intramolecular hydrogen bond of 4′X and 4X substituted 2′(OH)chalcones

Journal of Molecular Structure THEOCHEM (1999)

A. Devia F.H. Ferretti C.A. Ponce F. Tomás

10.1016/s0166-1280(99)00239-0

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Citations (15)

Laboratorio Remoto: Rejillas Periódicas Submicrométricas

Extensionismo Innovación y Transferencia Tecnológica (2023)

Guillermo P. Ortiz R. H. Romero C.A. Ponce Víctor Toranzos Luiza Rios

Presentamos un diseño de laboratorio remoto compatible con los requerimientos para establecer un nodo FaCENA en la red R-LAB administrada por el CONFEDI. Consideramos los antecedentes sobre puesta en servicios de laboratorios remotos a nivel nacional e internacional; definiciones de metas y alcances pedagógicos; formulaciones del problema del diseño y la realización de una propuesta preliminar. Proponemos un prototipo con definiciones sobre dispositivos, instrumentos de medición, diseño y fabricación, mediante una interfaz del tipo modular muy versátil para conectividad vía páginas web.

Open Access Publishing

10.30972/eitt.827243

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Citations (0)

Theoretical study on hydration of two particular diazanaphthalenes

Journal of Molecular Structure THEOCHEM (2005)

César A. Spedaletti Mario R. Estrada Graciela N. Zamarbide Juan C. Garro C.A. Ponce

Cinnoline

Phthalazine

Basis (linear algebra)

10.1016/j.theochem.2004.12.042

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Citations (2)

Association of Primary Pneumocystis carinii Infection and Sudden Infant Death Syndrome

Clinical Infectious Diseases (1999)

Sergio L. Vargas C.A. Ponce Walter T. Hughes Ann E. Wakefield Juan Carlos Weitz

To delineate clinical and histological features of the first Pneumocystis carinii infection affecting the immunocompetent host, P. carinii-specific histological stains were performed on autopsy lung specimens from 534 consecutive pediatric patients (those with AIDS and malignancies were excluded) in Santiago, Chile. P. carinii clusters were found in 4 (25%) of 16 infants who died of no apparent cause at arrival to the emergency department, and in 10 (2.9%) of 342 infants who died of multiple conditions at the hospital (P=.002, Fisher's exact test). This prompted us to analyze additional series of infants with sudden infant death syndrome (SIDS). In 161 additional SIDS cases, 47 (35.1%) of 134 infants from Chile and 4 (14.8%) of 27 infants from Oxford, United Kingdom, were found to have P. carinii clusters in the lungs. The quantity of P. carinii cysts was small compared with the numbers seen in immunocompromised hosts with P. carinii pneumonitis. This study provides histological evidence that primary P. carinii infection is associated with SIDS.

Pneumonitis

10.1086/313521

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Citations (94)

Ab initiostudy of the elastic properties of single and polycrystal TiO₂, ZrO₂and HfO₂in the cotunnite structure

Journal of Physics Condensed Matter (2008)

M. Caravaca Julio C. Miño V J Pérez R. Casali C.A. Ponce

In this work, we study theoretically the elastic properties of the orthorhombic (Pnma) high-pressure phase of IV-B group oxides: titania, zirconia and hafnia.By means of the self-consistent SIESTA code, pseudopotentials, density functional theory in the LDA and GGA approximations, the total energies, hydrostatic pressures and stress tensor components are calculated.From the stress-strain relationships, in the linear regime, the elastic constants C i j are determined.Derived elastic constants, such as bulk, Young's and shear modulus, Poisson coefficient and brittle/ductile behavior are estimated with the polycrystalline approach, using Voigt-Reuss-Hill theories.We have found that C 11 , C 22 and C 33 elastic constants of hafnia and zirconia show increased strength with respect to the experimental values of the normal phase, P2 1 /c.A similar situation applies to titania if these constants are compared with its normal phase, rutile.However, shear elastic constants C 44 , C 55 and C 66 are similar to the values found in the normal phase.This fact increases the compound anisotropy as well as its ductile behavior.The dependence of unit-cell volumes under hydrostatic pressures is also analyzed.P-V data, fitted to third-order Birch-Murnaghan equations of state, provide the bulk modulus B 0 and its pressure derivatives B 0 .In this case, LDA estimations show good agreement with respect to recent measured bulk moduli of ZrO 2 and HfO 2 .Thermo-acoustic properties, e.g. the propagation speed of transverse, longitudinal elastic waves together with associated Debye temperatures, are also estimated.

Shear modulus

Debye model

Orthorhombic crystal system

10.1088/0953-8984/21/1/015501

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Citations (71)

macroscopic elastic anisotropy in tough ceramics from the single crystal elastic behaviour

Procedia Engineering (2011)

M. Caravaca R. Casali C.A. Ponce

The modern techniques for engineering analysis are based on a deep understanding of the proportional relationship between stress and strain and the description in terms of isotropic elastic constants, in many cases, is enough. In anisotropic materials the knowledge of the elastic constants is important for the manufacturing process and for micro mechanical modelling behaviour of the material to develop the new composite materials. Theoretical calculations of elastics constants and anisotropies are applied to tough ceramics ZrO2, HfO2 and in rutile TiO2 and SnO2. Their dependence of the residual hydrostatic stress in the crystal are given. The microscopic elastic anisotropy determined in this work, could be applied in the macro scale in the case the constituent grains have a preferred orientation in the crystal lattice or the grains shape is not spherical (faceted) and it is aligned to a common crystal axis. To cover the case where the grains are distributed at randomly, the Voigt-Reuss-Hill polycrystalline approach is applied to obtain the average values of Young, bulk, shear modules, Poisson coefficient and sound velocity in the transversal and longitudinal modes. These theoretical results, could be useful in the interpretation of experimental results obtained with the method known as diffraction elastic constant (DEC).

Hydrostatic stress

Lattice constant

10.1016/j.proeng.2011.04.357

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Citations (4)

Protonation and deprotonation of hydroxamic acids. An MO ab initio study

Journal of Molecular Structure THEOCHEM (1996)

Lázaro J. Yamı́n C.A. Ponce Mario R. Estrada Francisco Tomás Vert

Hydroxamic acid

Gaussian orbital

Hydrogen atom

10.1016/0166-1280(95)04281-4

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Citations (24)

Search for Primary Infection by Pneumocystis carinii in a Cohort of Normal, Healthy Infants

Clinical Infectious Diseases (2001)

Sergio L. Vargas Walter T. Hughes Marı́a Elena Santolaya Ana Victoria Ulloa C.A. Ponce

To determine whether Pneumocystis carinii is associated with clinical illness in the competent host, 107 normal, healthy infants were enrolled in a 2-year prospective cohort study in Chile. P. carinii was identified by specific stains and nested-deoxyribonucleic acid (DNA) amplification of the large subunit mitochondrial ribosomal ribonucleic acid gene of P. carinii f. sp. hominis, and seroconversion was assessed by enzyme-linked immunosorbent assay of serum samples drawn every 2 months. P. carinii DNA was identified in nasopharyngeal aspirates obtained during episodes of mild respiratory infection in 24 (32%) of 74 infants from whom specimens were available for testing. Three (12.5%) of those 24 infants versus 0 of 50 infants who tested negative for P. carinii had apnea episodes. Seroconversion developed in 67 (85%) of 79 infants who remained in the study by 20 months of age and occurred in the absence of any symptoms of disease in 14 (20.8%). The study indicates that P. carinii DNA can be frequently detected in healthy infants, and it raises the hypothesis that they may be an infectious reservoir of P. carinii in the community. Further investigation is needed to identify whether P. carinii causes overt respiratory disease in infants.

Primary (astronomy)

10.1086/319340

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Citations (310)

Magnetic properties for the Mn2GeTe4 compound

Journal of Magnetism and Magnetic Materials (2008)

M. Quintero E. Quintero D. Caldera E. Moreno M. Morocoima

Bohr radius

10.1016/j.jmmm.2008.09.003

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Citations (8)

ChemInform Abstract: Spectroscopic and Theoretical Studies on the Internal Rotational Barrier of 1‐Acetylcyclohexene