Revista Comunicaciones Científicas y Técnológicas
Revista de contenido científico de la Facultad de Ciencias Naturales y Matemática de la Universidad de El Salvador
Preparation of low cost SERS-substrates for virus characterization
Raman spectroscopy is a technique that allows the characterization and detection of a wide range of molecules. The characterization of biomolecules and viruses has been a novel application in the last decades. A relevant problem for applying this technique is the low intensity of the Raman signal and the low concentration of the analyte, which makes the identification of molecules and viruses quite difficult. An alternative to overcome this problem is the use of surface- enhanced Raman spectroscopy (SERS). This involves the use of SERS-substrates that generally are very expensive and can only be used once. In this work, we report the preliminary results of virus detection by SERS using low-cost homemade substrates and commercially available substrates. Characteristic Raman peaks associated with the influenza virus were detected. The results obtained with the homemade SERS-substrates are comparable to the obtained by using the comercial ones.
Copyright (c) 2022 https://creativecommons.org/licenses/by-nc/4.0
Hacia la reutilización de la palma Attalea cohune Mart., Arecaceae (corozo)
The corozo palm Attalea cohune Mart., Arecaceae, is endemic of Central America, South of Mexico, and Colombia, it is fire resilient and was cultivated by the ancestral Mayan communities. Currently, only the nut is commercially exploited for its oil, which is limited by the nut hardness that rapidly wears the machinery. This study targets at long term the potential exploitation of the male flower inflorescences. Its first phase is to further the extracts characterization. The essential oil was extracted by vapor distillation from the corozo male inflorescences in two different stages of development (A=before and B=after the panicle blossomed), the extraction yield and analyzed by gas chromatography coupled to flame ionization detector (GC-FID). The laboratory extracting conditions were optimized. The A product was below 0.001%, while the anhydrous B product was 0.02%. The chromatogram peaks were preliminary assigned, by comparison with standards, as monoterpenoids: eucalyptol, linalyl acetate, alfa-terpineol, and neryl acetate. This compounds have relevance in the cosmetic industry, extraction at industrial level as well as organoleptic analysis will be performed. Further research is ongoing.
Microestructural and ferroelectric analyses of Pb₁₋₃ₓ/₂Laₓ(Zr₀.₅₄Ti₀.₄₆)₁₋₅ᵧ/₄NbᵧO₃ soft ceramics.
Microstructural and ferroelectric analyses were carried out on Pb₁₋₃ₓ/₂Laₓ(Zr₀.₅₄Ti₀.₄₆)₁₋₅ᵧ/₄NbᵧO₃ ceramics, x = y = 0.004, 0.006, 0.008 and 0.01 mol%. Using Piezoresponse Force Microscopy (PFM) and piezoelectric Hysteresis Loop (HL), ferroelectric behavior, and ferroelectric domain sizes were determined. Grain size (as determinate by SEM) and ferroelectric domain area decrease with the increase of dopant concentration from 3 μm to 1 μm and from 0.56 μm² to 0.32 μm², respectively. The maximum remnant polarization was obtained for Pb₀.₉₈₅La₀.₀₁Zr₀.₅₄Ti₀.₄₆)₀.₉₈₇₅Nb₀.₀₁O₃, showing that samples polarize easier with higher La³⁺ and Nb⁵⁺ dopant concentration. The coercive field does not show significant differences as the La and Nb content is varied. Grains tend to be single crystals as the La³⁺ and Nb⁵⁺ dopant concentration is increased.
Copyright (c) 2022 M.D. Durruthy-Rodríguez, M. Hernández-García, J.M. Yañez-Limón, F.J. Espinoza Beltrán, D. Rivero Ramírez https://creativecommons.org/licenses/by-nc/4.0
Etnoecológia como identidad étnica presente en los territorios de los Jicaques de la Montana de la Flor a principios del Siglo XX
The present study was carried out in order to make known, analyze, interpret what was observed and lived by V. Wolfgang von Hagen; during his expedition to Honduras between 1937 and 1938, in which historical antecedents are described about the origin of the community of Jicaques (Tolupanes), from the Montaña de la Flor, located in the departments of Francisco Morazán and Olancho, Honduras. At the same time, it allows us to know geographical and ecological data, type of vegetation that existed in its environment, uses of plants and animals, hunting arts, beliefs, gender roles and the social structure, by which they are governed and the relationships that they establish with people outside their communities. It was determined that the Jicaques make use and exploitation of approximately 35 species of plants and 10 species of animals (between wild and domestic) either for food, clothing, hunting or ornamentation. In addition, a record of 45 specimens was found in the database of the New York Botanical Garden and Missouri Botanical Garden.
White light emitting diode prototypes based on cadmium sulfide and graphene carbon quantum dots
During the last years, semiconductor quantum dots (QDs) have attracted great attention due to the outstanding properties for solid-state lighting, display technology, biosensors, among others. White light emitting diodes (WLEDs) using down conversion approach is one of the new attractive alternatives in solid-state lighting. However, these devices present several shortcomings as near-UV light escape and QD-polymer incompatibility. In this work, we propose alternative
Por este medio queremos expresar nuestro profundo pesar por la muerte de la MSc. Yanira Elizabeth López Ventura, (1968-2020) docente de la Escuela de Biología de la Facultad de Ciencias Naturales y Matemática de la Universidad de El Salvador. La Maestra López Ventura se graduó de la carrera de Licenciatura en Biología en 1996, luego viajo a Costa Rica para estudiar la Maestría en Agricultura Ecológica con énfasis en Recursos Fitogenéticos y Biotecnología, del Centro Agronómico Tropical de Investigación y Enseñanza (CATIE) en donde se graduó en 1999. - Fue asesora de múltiples trabajos de investigación y fungió como tribunal evaluador en trabajos de graduación en el área de Biotecnología Vegetal para los niveles de pregrado y Maestría.
López Ventura, Yanira Elizabeth, 1968-2020
La recién aprobada Licenciatura en Biología Marina en la Universidad de El Salvador
Desde hace más de una década se concebía de suma urgencia la formación de cuadros profesionales en nuestro país, especializados en el estudio de mares y océanos. Hoy celebramos que finalmente haya sido aprobada en junio de este año en la Universidad de El Salvador, la Licenciatura en Biología Marina, que se impartirá en la Facultad de Ciencias Naturales y Matemáticas, la cual se apoyará con la capacidad científica y técnica instalada del Instituto de Ciencias del Mar y Limnología (ICMARES) y el Laboratorio de Toxinas Marinas (LABTOX). No dudamos que el aporte de los futuros biólogos marinos formados, será fundamental para el desarrollo de la investigación y la generación de normativas que contribuyan a la protección y manejo del mar territorial y sus recursos.
Carlos A. Montes de Oca, Milta Adela Retana de Rodríguez
Dentro de un plan general para la determinación de estructuras moleculares absolutas, hemos realizado las medidas de las magnitudes correspondientes para la determinación de la estructura de la tiómorfolina. (tetrahidro 1-4 tiazano), en base a la magnitud y signo de su constante de Kerr molecular. El valor de ooKm experimental tal obtenido para dicha sustancia fue de \-28.2 (± 5. 7) x 10-12 .
Milta Adela Retana de Rodríguez Retana de Rodríguez
Copyright (c) 2021 https://creativecommons.org/licenses/by-nc/4.0
Las mariposas de El Salvador. Primera parte. Papilionidae
This work is basically a taxonomic guide to the butterflies of the family PAPILIONIDAE in El Salvador, centered on a taxonomic key, and supplemented by some general biological notes, illustrations of all the described species, plus a brief summary of what has been done with this group in this country so far. At the same time it represents the beginning of an effort to describe in this same manner, in the inmediate future, all the butterflies (Papilionoidea) of El Salvador
Divergencia genética como resultado de adaptación a alturas diferentes en Rana neotropicales del grupo Rana pipiens
Frogs classified as Rana pipiens represent a group of closely related species. In this study, four populations belonging to this group, but inhabiting different environments at different altitudes in Costa Rica were compared in respect to (1) norphological variation and (2) reproductive compatibility. No cline was evident in the shape of the snout, but a significant decrease in size of both sexes was found to occur in a clinal manner with increase in altitude. Artificial crosses indicate a significant decrease in reproductive compatibility between the high-altitude population and those inhabiting lower altitudinal zones. It is proposed that the clinal change in size and the reduced viability of ''hybrids" between parents from high and low altitude populations may indicate a genetic divergence and formation of a new species in process by the frogs inhabiting the summit of Volcán Turrialba. Speciation by this mechanism may be occurring throughout the isthmus of Central America on numerous semi-isolated mountains and volcanoes.
Estudios de campo con ácido fosfonico 2-cloroetilo (Ethephon) en cafetos.
In this paper the compound 2 chloroethlyphosphonic acid (Ethephon) is shown to have dramatic effects on the uniformity of coffee fruit ripening and the increase in size of the coffee fruit. The cultivar Coffea arabica,L. variety Bourbon was used; the ethephon caused excesive fruit and-leaf abscission in the cultivar Coffea robusta L. in concentrations as low as 100 parts per million. Highest uniformity of fruit ripening (85 - 95%) was achieved with 500 parts per million ethephon in the sun, and 750 parts per million in partial shade. Defoliation and fruit drop were within acceptable limits. An increase in fruit size was noted only when ethephon was applied during phase II of fruit growth, while highest uniformity of ripening was achieved when ethephon was applied early in Phase III of the fruit growth curve. By giving coffee growers a "single harvest" capability and by increasing berry size, ethephon shows great potential in the culture of coffee.
Algunas especies de artrópodos y sus enemigos naturales en El Salvador
A series of 16 cases are presented in which species of arthropods (one arachnid and 15 insects) are attacked by natural enemies, mostly predators and pathogens.An emphasis is placed on the fact that some of the species discussed, while being inocuous in El Salvador, are of economic importance in other countries, which supports the idea that the beneficial insects listed may be of importance in the regulation of their populations.
Siguiendo las huellas de Koebele: Un viaje a Australia.
An account is made about explorations carried out in the south of Australia by the route taken by Koebele in 1888, in search of the cottony-cushion scale, Icerya purchasi Mask.and its natural enemies, the predatory beetle Rodolia cardinalis Muls. and the fly parasite Cryptochetum iceryae Willis. The principal aim of the explorations was to prove if the ecological relationships of the three species in Australia were equivalent to those shown in California, where the scale was accidentally introduced around 1869 and its enemies brought from Australia twenty years later. The results provided strong support for such hypothesis and a detailed study to be carried out in Australia is suggested.
Escama algodonosa Icerya purchasi Maskel
Pulsos electromagnéticos planos en sistemas de referencia inerciales que están en movimiento relativo uniforme en el vacío.
In this article, the motion of plane electromagnetic pulses in two inertial frames having a uniform relative motion in a vacuum is discussed. It will be shown that if one has a plane electromagnetic pulse in one of the frames, then one will also have a plane pulse in the other frame. The analysis given here may be useful in teaching the theory of special relativity
Programación dinámica . Problema de reemplazo
Here it is exposed a Dynamic Programming's example which shows a direct application of the Principle of Optimality in multi-stage problems. Although the application of the inside problem is reduced to those cases in which it is necessary to take only two decisions, there exist many problems of that kind in real situations, hence its importance. Moreover, the way of solution showed here can be followed even by those not very much acquainted with Dynamic Programming. First in stablishing the Principle of Optimality and one of the most important promoters of the theoretical principles which govern this recent variety of Mathematical Programming is R. E. Bellman.
Presentación de Comunicaciones segunda época vol.1 no.1 marzo 1972
Después de 12 años de ausencia reaparece "COMUNICACIONES", en esta ocasión como vocero oficial de las actividades científicas del Instituto de Ciencias Naturales y Matemáticas. Cambios de gran trascendencia se han realizado en la Universidad de El Salvador desde la época en que apareció por última vez COMUNICACIONES, llevando todos ellos como Única finalidad hacer de la Institución un auténtico emporium científico y cultural.
In 1974, a flower in a bush of Hibiscus rosa-sinensis L. was observed to produce a fruit and seeds. This was surprising, for we did not have references on this phenomenon.
Excreción de cloruro de sodio en dos poblaciones de la rana neotropical, Rana palmipes Spix, en el sur del Estado de Veracruz, México.
Twenty-four specimens of Rana palmipes Spix from two populations in southern Veracruz, México, were studied in an effort to determine whether or not a population living in fresh water of a higher than normal NaC1 content would possess a physiological mechanism for concentration and excretion of excess NaC1, and, if so, what method would be employed. The normalities of the water in the two selected collecting sites were too near the same value to render conclusive results, but on the basis of the infom1ation gained it is concluded that frogs in the higher normality water are not excreting urine of higher salt concentration than are frogs of the fresh-water population, and therefore may be excreting more urine per unit of body size. No means of measuring this factor was available.
La Fauna de crustáceos marinos de El Salvador, problemas y proyecciones
It is made a brief description of the Decapod Crustaceans groups studied in El Salvador and it is also reported the new discoveries within the Porcellanidae, Dromiida, Calappidae, Leucosiidae and Majidae families. It is sketched some of the more serious problems the salvadorean sea fauna is exposed to and, in a general sense, some recommendations are given.
This monography presents further reflections and schemes about perceptive intuitive data obtained by means of teaching experience. It tries to expose theoretical space concerned to educational problems, using in it basic ideas as well as "Teaching Mood"; besides, that, it tries to describe educative process structures and ideological effects produced by them on people. At the et it offers a sketch on the pedagogical which instruments which have been applied on basic level courses at the University of El Salvador.
Ecología y explotación de las Dioscoreáceas en El Salvador, C. A.
The main objective of this work was to make a census of the different Dioscoreaceae species of commercial value which are part of the salvadorean flora. A sinecological analysis and a study of their distribution is also being carried out. For sampling purposes, the country was divided into three zones: one along the coastal side, a central area, and one along the Honduran border. Several species were found, and three of them have been identified, out of which two have commercial value because of their steroid content (Dioscorea floribunda Martz., and Gal., y Dioscorea mexicana Guillemin). They are widely distributed in the coastal and central zones at 300-700 meters above sea level, mainly along river sides, associated with Bactris balanoidea (Oerst) Wendl., and Randia armata (Swartz), D.C. In the central zone, specially an rock substrates, it was most frecuently associated with Curatella americana L. An irrational exploitation of the commercial species by national and foreign has been detected. The same type of explotation has been prevented in Mexico, which accounts for the increasing explotation of these species in Central American countries. These plants were successfuly grown experimentally using rhizome sections.
Las nubes de alta velocidad de la galaxia y la estructura del gas interestelar
This paper presents results which further clarify morphological and thermodynamical aspects of the interstellar medium in the peripheric regions of the Galaxy. It is composed of (l) a part of theoretical analysis, in which a hierarchical structure of the gas, in three phases of different temperatures and densitics, is postulated; and (2) a mainly observational part in which the results of A 21 cm observations are presented showing and agreement with theoretical results. The picture proposed by this study shows the peripheric galactic gas conformed in nebular structures which rotate with the Galaxy and, given their presumably big distances, show high values of the radial velocities. They are interpreted as representative of two phases in pressure, thermal and ionization equilibrium between them and with a third phase, "internebular", at a temperature higher than 20000 K
Evidencia electroforética para especiación entre poblaciones del sapo Bufo valliceps Wiegmann
Variation in proteins from the sera of three populations of the toad Bufo valliceps Wiegmann is examined by use of cellulose polyacetate electrophoresis, and the d´fferences found are compared to ( l) superficial differences in morphology, (2) differences in toad habitats as a reflection of the biotic provinces in which the toads live, and ( 3) the distances which separate the three populations. It is suggested 34 that speciation through distance instead of through isolation by geographic barriers may be occurring. Also suggestions are made for future research concerning this phenomenon.
Importancia que puede tener en El Salvador, Centro América la Casuarina equisetifolia foster
In this work an analysis is made of the growth and propagation of the Casuarina equisetifolia forster, from its introduction into the country to the present day. Growth is analyzed according to base and cover area; and a map of the plant's distribution is presentcd along with the various uses on the plant itself.
Notas ecológicas sobre las poblaciones de Rothschildia aroma schaus (lepidoptera: Saturniidae) y sus enemigos naturales
The life cycle of Rothschildia aroma and the effect of its natural enemies as control vectors of the population of this butterfly were investigated. Some variations were found in the percentages of parasitism reported by Quezada (1967). The variations founded are most evident in San Miguel and its surroundings ( one of the salvadorian cotton arcas) and for that reason a hypothesis was formulated concerning the possible action of insecticides sprayed in such places as. causes of the alterations in the biological levels of R. aroma, and its parasites. This hypothesis was tested using the X2 test of correlation.
Presentación de la Revista Comunicaciones tercera época vol. I, no. 1 enero de 1976
Es importante aclarar a nuestros lectores, que las publicaciones de la Segunda Epoca del vocero oficial de las actividades científicas de este Instituto, la revista COMUNICACIONES, se vieron lamentablemente interrumpidas a causa de la intervención gubernamental de nuestra Alma Mater, el pasado 19 de julio de 1972. Apartir de esa fecha, nuevas Autoridades se encargaron de dirigir nuestra Universidad y fue hasta en octubre de 1973 en que se inició la labor docente-administrativa.
Calvatia cyathiformis es una especie ampliamente distribuida en todas las zonas tropicales y subtropicales (Zoberi, 1972). Entre los reportes de este hongo se destacan los de Zeller & Smith ( 1964), Guzmán & Herrera ( 1969). Coker & Couch (1974) y Guzmán (1977) para Norteamérica, Garner (1956) y Dennis ( 1970) para Centro y Suramérica; Bottomley ( 1948), Dissing & Lange ( 1962) y Dring ( 1964) han reportado esta especie en Africa, Cunningham ( 1942) en Australia y Ahmad (1952) en Pakistán. No es de nuestro conocimiento que hasta la fecha se haya reportado este gasteromiceto en la zona comprendida entre Costa Rica y México. En El Salvador ha sido colectado repetidamente en la laguna El Jocotal, el valle de Aguilares y el Departamento de Sonsonate, en lugares semi-áridos, de clima cálido y a bajas elevaciones. Las colecciones salvadoreñas se encuentran depositadas en el Herbario de la Universidad de El Salvador (ITIC).
Copyright (c) 2021 Gustavo A. Escobar Escobar, Judith D. Toledo https://creativecommons.org/licenses/by-nc/4.0
La flora del pedregal de san isidro: notas sobre la fisionomía y dominancia del estrato arbóreo
A series of 15 stands of tree vegetation was sampled in El Pedregal de San Isidro (Sonsonate, El Salvador) from 850 to 1175 m.a.s.l. a long a discontinous strip of 6 km. long and O. 5 km. wide. It was analyzed physiognomically and quantitatively to determine species dominance. Results show that the dominant species was Bombax ellipticum; codominants with it were Lysiloma auritum, Lysiloma demostachya, Cochlospermun vitifolium, Bursera simaruba, Plumeria acutifolia, and Tecoma stans; while Bocconia arborea, Erythrina sp., Cecropia sp. and an unidentified member of the Leguminosae, were found to be suppressed. Trema micrantha and Cecropia sp. were the dominant species in disturbed areas. Moreover the distribution of Hauya lucida, Piscidia grandifolia and Bursera graveolens suggests a response to an altitudinal gradient. The structure of the study site is physiognomically described briefly.
Pedregal de San Isidro (Sonsonate, El Salvador)
Cultivo y algunos datos etnobotánicos del "loroco" Fernaldia pandurata Woodson
In this work the life cycle of "loroco" has been described. This is a Wild plant from our flora with perspective of cultivation due to its elaboration as a food called "pupusa". Etnobothanical facts of the plant and methods for cultivation are also given.
Cerro Verde: análisis preliminar de la vegetación arbórea en zonas de disturbio
An ecological study of disiurbance zones of the tree vegetation of Cerro Verde is presented. Density, frequency, biomass, and importance value index of the species sampled are calculated; dominant species are: Peryrneniurn grande, Hernsl, Lippia miriocephala, Schlecht y Cham: Roupala borealis, Hemsl. A descriplion of secundary succession is included.