Universitas Scientiarum最新文献

{"title":"Neutron Density Calculation Using the Generalised Adams-Bashforth-Moulton Method","authors":"D. Suescún-Díaz, Diego Alejandro Rasero-Causil, J. Lozano-Parada","doi":"10.11144/javeriana.sc24-3.ndcu","DOIUrl":"https://doi.org/10.11144/javeriana.sc24-3.ndcu","url":null,"abstract":"This paper presents a numerical solution to the equations of point kinetics for nuclear power reactors, a set of seven coupled differential equations that describe the temporal variation of neutron density and the concentration of delayed neutron precursors. Due to the nature of the system, we propose to numerically solve the point kinetics equations by implementing the Adams-Bashforth and Adams-Moulton methods, which are predictor-corrector schemes with their respective modifiers to increase precision. The proposed method was tested computationally for different forms of reactivity with up to six groups of delayed neutron precursors. This method was used in a recent publication to solve the inverse problem of finding the reactivity. In this work, it is shown that it can also be used for the calculation of nuclear power, that it is simple and easy to implement, and that it produces good results when compared with those in the literature for neutron population density and concentration of delayed neutron precursors.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.11144/javeriana.sc24-3.ndcu","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42734192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of two sample preparation methods for the determination of cadmium, nickel and lead in natural foods by Graphite Furnace Atomic Absorption Spectrophotometry","authors":"David Romero-Estévez, G. Yánez-Jácome, Karina Simbaña-Farinango, Pamela Y. Vélez-Terreros, H. Navarrete","doi":"10.11144/javeriana.sc24-3.eots","DOIUrl":"https://doi.org/10.11144/javeriana.sc24-3.eots","url":null,"abstract":"Environmental pollution allows heavy metals to interact with ecosystems, bioaccumulating and passing through the food chain. Animals and human scan consume contaminated species and reach toxic and harmful concentrations in their organisms. While there are international regulatory frameworks for heavy metal contents, these are not always known or suitable for local conditions. This situation calls for the development of locally-applicable analytical methods for the determination of heavy metal concentrations in common vegetal and animal food products. Two established methods (AOAC999.11, based on sample drying and calcination, and IPNAC-06-00, based on microwave-assisted acid digestion) were comparatively tested at the CESAQ-PUCE laboratory in Quito, Ecuador, to determine their suitability. Sample matrices used were non industrial, non-organic tomato, lettuce, and beef commonly found in local markets. Heavy metals tested were cadmium, nickel, and lead. Test guidelines and comparative parameters were based on AOAC(2002) and included quantification limits, repeatability variation coefficients, intermediate precision percentages, accuracy and calculated expanded uncertainties. Unlike method AOAC999.11, method IPNAC 06-00 performance for all parameters was with in the range of recommended expected values as per AOAC, and was therefore deemed more suitable to be applied under the local CESAQ-PUCE laboratory conditions. The validation of method IPNAC-06-00 demonstrated its local applicability. In addition, IPNAC 06-00 can beused by similar laboratories to assess contaminants concentrations and improve the base line information concerning human exposure to toxic metals.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.11144/javeriana.sc24-3.eots","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43748884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmental and cultured cyanobacteria as sources of Aedes aegypti larvicides","authors":"Farja I. Ayala, Laura M Becerra, J. Quintana, L. Bayona, Freddy A. Ramos, M. Puyana, F. Duque, L. Castellanos","doi":"10.11144/javeriana.sc24-3.eacc","DOIUrl":"https://doi.org/10.11144/javeriana.sc24-3.eacc","url":null,"abstract":"In tropical countries, the control of the mosquito Aedes aegypti is a public health priority due to its role as a vector of important viral diseases. Marine cyanobacteria are recognized as abundant sources of bioactive compounds, and they constitute a potential source of insecticides useful for controlling mosquito populations and preventing epidemic outbreaks. We collected 30 benthic cyanobacterial mats in Providencia and Rosario islands (in the Colombian Caribbean) belonging to the genera Phormidium, Symploca, Oscillatoria, Lyngbya, Pseudoanabaena, Leptolyngbya, Moorea, and Dapis. Fractions of organic extracts from the most abundant environmental samples were evaluated in three bioassays, assessing (i) larvicidal activity against A. aegypti, (ii) toxicity against the brine shrimp (Artemia salina) nauplii, and (iii) acetylcholinesterase inhibition. Non-polar fractions exhibited larvicidal activity. The polar fraction from one Dapis pleuosa extract showed larvicidal activity without being toxic against A. salina nauplii. Extracts from Moorea producens exhibited the greatest toxicity against A. aegypti larvae and A. salina nauplii. From 23 cultured cyanobacterial samples, only five grew under laboratory conditions and produced enough biomass to yield organic extracts. Of these, three extracts showed strong larvicidal activity, but only the extract from Phormidium tenue showed reduced toxicity against A. salina nauplii. We detected variation among the chemical profiles and larvicidal activity of cyanobacterial consortia depending on sites and dates of collection. Our findings suggest that despite variation in chemical profiles, extracts of marine benthic cyanobacteria can be further developed as effective control agents against insect vectors, in their larval stages. The culture of marine benthic cyanobacteria needs to be further explored to provide enough biomass leading to the identification of bioactive compounds with public health applications.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.11144/javeriana.sc24-3.eacc","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44030723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptive model predictions of daily total column ozone over the Amazon Inter-Tropical Confluence Zone","authors":"Julio César González-Navarrete, Julián Salamanca","doi":"10.11144/javeriana.sc24-3.ampo","DOIUrl":"https://doi.org/10.11144/javeriana.sc24-3.ampo","url":null,"abstract":"The aim of this paper is to broaden the scope of a recent adaptive model in order to obtain predictions of total column ozone (TCO) trends over the Amazon Inter-Tropical Confluence Zone (ITCZ). The adaptive model makes daily TCO predictions over the tropical equator-Andes-Region, relying on seasonal patterns and the solar cycle. This study uses daily observations of the sunspot number cycle, given by the World Data Center for the production, preservation and dissemination of the international sunspot number (Royal Observatory of Belgium), and satellite total-column ozone data, collected by NASA (January 1979 to April 2018), for two Colombian locations: one in and one adjacent to the ITCZ. The agreement between daily total-column predictions by the adaptive model and satellite observations is excellent. Daily averaged relative errors around of 3.7 % and 2.8 % for both locations are reported herein.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49188593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probing the Pharmacological Binding Properties, and Reactivity of Selective Phytochemicals as Potential HIV-1 protease Inhibitors","authors":"A. Akhtar, Waqar Hussain, N. Rasool","doi":"10.11144/javeriana.sc24-3.artf","DOIUrl":"https://doi.org/10.11144/javeriana.sc24-3.artf","url":null,"abstract":"The HIV-1 protease plays an essential role in the replication cycle of HIV-1; therefore there is a direct need to develop novel inhibitors of the HIV-1 protease, which can cease the viral replication. The present study targets the discovery of potential inhibitors of HIV-1 protease from a set of phytochemicals. From 2505 phytochemicals, 108 compounds were docked, after screening, with the HIV-1 protease to analyze their inhibitory potential against the protease. DFT analysis was also conducted to study the reactivity of strongly docked compounds. Out of 108 phytochemicals, 38 compounds showed binding affinity greater than the desired threshold. Reactivity of these 38 inhibitors was also high as compared to other compounds, based on the DFT results. These results suggest that the selected 38 phytochemicals are drug candidates and they have the potential to be effectively used against HIV in the future.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.11144/javeriana.sc24-3.artf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44419557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-radial functions, nonlocal operators and Markov processes over p-adic numbers","authors":"L. F. Chacón-Cortés, O. Casas-Sánchez","doi":"10.11144/javeriana.sc24-2.nrfn","DOIUrl":"https://doi.org/10.11144/javeriana.sc24-2.nrfn","url":null,"abstract":"The main goal of this article is to study a new class of nonlocal operators and the Cauchy problem for certain parabolic-type pseudodifferential equations naturally associated with them. The fundamental solutions of these equations are transition functions of Markov processes on an n-dimensional vector space over the p-adic numbers. We also study some properties of these Markov processes, including the first passage time problem.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.11144/javeriana.sc24-2.nrfn","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42900021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Amperometric detection of triclosan with screen-printed carbon nanotube electrodes modified with Guinea Grass (Panicum maximum) peroxidase","authors":"Angie E. Orduz, J. A. Gutiérrez, S. Blanco, J. Castillo","doi":"10.11144/javeriana.sc24-2.adot","DOIUrl":"https://doi.org/10.11144/javeriana.sc24-2.adot","url":null,"abstract":"Triclosan is a compound with antimicrobial activity broadly used in consumer products. Because of its well documented toxicity, the amount of triclosan present in different products needs to be tightly controlled. This paper outlines a new amperometric sensor for triclosan detection consisting of a screen-printed carbon nanotube electrode (SPCNE) modified w ith Guinea grass peroxidase (GGP). The GGP-modified S PCNE was a ble t o d etect an enhanced electrochemical response of triclosan, unlike the bare SPCNE. The cyclic voltammograms of the GGP-modified SPCNE in a solution of potassium ferrocyanide showed an increase in the current values and linearity between scan rates and oxidation peak currents, suggesting a surface controlled process. The GGP-modified SPCNEs howed an excellent electrocatalytic activity to triclosan oxidation, at a redox potential of 370 mV, in the presence of hydrogen peroxide, exhibiting a linear response between 20 mM to 80 mM and a detection limit of 3 µM. This new amperometry system, based on carbon nanotubes integrated with GGP, becomes a potential tool for environmental analysis and food quality control.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.11144/javeriana.sc24-2.adot","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49607451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global dynamics of humoral and cellular immune responses to virus infection","authors":"Miller Cerón-Gómez, H. Yang","doi":"10.11144/javeriana.sc24-2.gdoh","DOIUrl":"https://doi.org/10.11144/javeriana.sc24-2.gdoh","url":null,"abstract":"We study the global stability of a model of virus dynamics with consideration of humoral and cellular immune responses. We use a Lyapunov direct method to obtain sufficient conditions for the global stability of virus free and viruspresence equilibriums. First, we analyze the model without an immune response and found that if the reproductive number of the virus is less than or equal to one, the virus-free equilibrium is globally asymptotically stable. However, for the virus-presence equilibrium, global stability is obtained if the virus entrance rate into the target cells is less than one. We analyze the model with humoral and cellular immune responses and found similar results. The difference is that in the reproductive number of the virus and in the virus entrance rate into the target cells appear parameters of humoral and cellular immune responses, which means that the adaptive immune response will cease or control the rise of the infection.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48056796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical constituent analysis of the Babassu (Orbignya phalerata Mart.) mesocarp","authors":"Gabriela Batista de Farias, Jean Lucas Da Silva Rodrigues, Maria Nilce De Sousa Ribeiro, Lyege Oliveira Magalhães, A. Ferreira, M. P. Lima","doi":"10.11144/javeriana.sc24-2.ccao","DOIUrl":"https://doi.org/10.11144/javeriana.sc24-2.ccao","url":null,"abstract":"The Babassu nut (Orbignya phalerata Mart.) mesocarp is traditionally transformed to flour and consumed in some Brazilian areas for its attributed medicinal activity; however, its chemical properties remain to be elucidated. The present work aimed at analyzing the babassu mesocarp phytochemical constituents. Babassu nut samples were collected in the Brazilian Amazon, and their mesocarps were prepared and macerated in different solvents. The chromatographic fractionation of selected methanol extracts yielded three fractions, A-5, A-6, and B-1 that were characterized with high resolution methods. Fraction A-5 was characterized through GC/MS as a fatty acid mixture with predominance of eicosanoic (38.67 %) and 11-octadecanoic (21.71  %) acids. Fraction A-6 was characterized by the presence of three phytosteroids (32.02 %), sesquiterpene (nerolidol; 24.89 %), and diterpene (17-acetoxy-19-kauranal; 15.17 %). The 1H and 13C NMR spectra on fraction A-6 showed characteristic chemical shifts for its compounds. Compound B-1 was identified as ergostanol-3-benzoate based on NMR experiments in one and two dimensions. These results constitute the first identification of babassu mesocarp chemical constituents in 1 and 2-dimensions, paving the way to understanding its role in popular medicine.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.11144/javeriana.sc24-2.ccao","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48476435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphology and morphometric relationships for sagitta otoliths in Lutjanus argentiventris (Pisces: Lutjanidae) and Hyporthodus acanthistius (Pisces: Serranidae) from the Colombian Pacific Ocean","authors":"Vladimir Puentes-Granada, P. A. Rojas, Giovanni Pavolini, C. Gutiérrez, Angel Villa","doi":"10.11144/JAVERIANA.SC24-2.MAMR","DOIUrl":"https://doi.org/10.11144/JAVERIANA.SC24-2.MAMR","url":null,"abstract":"Fish earstones, or otoliths, are  inner ear structures that can be studied to determine a fish’s age and are a source of taxonomically informative data. In the present work, sagitta otoliths of the Yellowtail snapper (Lutjanus argentiventris) and the Red grouper (Hyporthodus acanthistius) were collected in the Colombian Pacific, and their key morphological features were studied. Otoliths of the Yellow tail snapper were distinctly concave by their distal surface, revealing features shared with species of its genus (Lutjanus). Red grouper otoliths were elliptic and compressed laterally by their proximal surface, bearing similarities to those of other Serranid species. Morphometric relationships between otolith size weight and whole fish size and weight were also studied. In Red groupers significant statistical morphometric relationships between otolith and body features were found via power regression models; successfully relating otolith length with total fish length, otolith weight with total fish length, otolith length with total fish weight, and otolith weight with total fish weight. No significant morphometric relationships were found for the Yellow snapper data. In both fish species, otolith transversal sections proved best to identify its internal features and to distinguish otolith growth rings, as a method for determining the specimen’s age.","PeriodicalId":39200,"journal":{"name":"Universitas Scientiarum","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.11144/JAVERIANA.SC24-2.MAMR","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41363477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}