Artículos Científicos

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1020 steel coated with Ti/TiN by Cathodic Arc and Ion Implantation
(Institute of Physics Publishing, 2017-03-08) Bermeo, F.; Quintana, Juan Pablo; Kleiman, Ariel; Sequeda, Federico O.; Márquez, Adrianna Beatriz
TiN coatings have been widely studied in order to improve mechanical properties of steels. In this work, thin Ti/TiN films were prepared by plasma based immersion ion implantation and deposition (PBII&D) with a cathodic arc on AISI 1020 steel substrates. Substrates were exposed to the discharge during 1 min in vacuum for the deposition of a Tiunderlayer with the aim of improving the adhesion to the substrate. Then, a TiN layer was deposited during 6 min in a nitrogen environment at a pressure of 3xl0-4 mbar. Samples were obtained at room temperature and at 300 °C, and with or without ion implantation in order to analyze differences between the effects of each treatment on the tribological properties. The mechanical and tribological properties of the films were characterized. The coatings deposited by PBII&D at 300 °C presented the highest hardness and young modulus, the best wear resistance and corrosion performance. © Published under licence by IOP Publishing Ltd.
1D lanthanide coordination polymers based on lanthanides and 4′-hydroxi-4-biphenylcarboxylic acid: Synthesis, structures and luminescence properties
(Academic Press Inc., 2019-03-29) D'Vries, Richard F.; Gomez, German E.; Mondragon, Lina Paola; Onna, Diego; Barja, Beatriz C.; Soler-Illia, Galo J.A.A.; Ellena, Javier
Synopsis: A family of coordination polymers with formula [Ln(4-OHBBA) 3 (H 2 O) 2 ] with a new 3D supramolecular network topology was obtained. Luminescence properties were studied. Resume: A new family of 1D coordination polymers (CPs) based on 4′-hydroxi-4-biphenylcarboxylic acid (4-OHBBA) linker and lanthanide metals were obtained by hydrothermal synthesis. The compounds were fully characterized and present the general formula [Ln(4-OHBBA) 3 (H 2 O) 2 ] (where Ln = La, Pr), crystallizing in the monoclinic P2 1 /c space group. The CPs are formed by “fish bone-like” chains along [010] direction. Also, the topological analysis revels a 3D supramolecular structure with a 7-nodal 3,3,3,4,4,4,4-connected network and the (6.8 2 ) 2 (6 2 .8) 2 (6 3 .8 2 .10) 2 (6 3 ) 4 (6 5 .8) 2 (8 6 ) point symbol. The luminescence and chemical sensing tests of the europium doped compound was performed, finding that the Eu, Tb and Dy -doped samples exhibited dual emissions from the 4-OHBBA ligand and the lanthanide centres
A conceptual model for decentralized municipal wastewater management
(IWA Publishing, 2018-03-01) Bernal, Diana
This paper proposes a conceptual model for selecting the centralization level for wastewater management in urban areas, which is associated with main sewage collectors and wastewater treatment facilities. The model is supported in the Analytical Hierarchy Process (AHP) and Cost-Benefit Analysis. Additionally, the model is based on the results of variables and indicators identified previously through an expert consultation process and prioritized by Ranking and Rating Multi-criteria Analysis. Three municipalities of Colombia were used as case studies for model validation purposes. As a result, decentralized plans can be a viable option when their associated benefits are quantified.
A facile synthesis of stable β-amino-N-/O-hemiacetals through a catalyst-free three-component Mannich-type reaction
(Elsevier Ltd, 2017-03-02) Abonia, Rodrigo; Castillo, Juan C.; Garay, Alexander; Insuasty, Braulio; Quiroga, Jairo; Nogueras, Manuel; Cobo, Justo; D'Vries, Richard F.
A practical, straightforward and one-step procedure for the synthesis of novel and stable b-amino-N-/Ohemiacetals (i.e. c-aminoalcohols) is provided. The title compounds were obtained in good to excellent yields through an uncatalyzed three-component reaction by treatment of secondary amines with polyformaldehyde and electron-rich alkenes in acetonitrile as solvent at ambient temperature. The reactions proceeded with the formation of iminium ions, through a Mannich-type reaction, as the key intermediates for the generation of the target products. Single crystal X-ray analysis of derivative 4l confirmed unequivocally the structure and stability of the obtained compounds.
A low-cost, free-software platform with hard real-time performance for control engineering education
(John Wiley and Sons Inc., 2018-11-04) González Vargas, Andrés M.; Serna Ramirez, Juan M.; Fory Aguirre, Carlos; Ojeda Misses, Alejandro; Cardona Ordoñez, John M.; Tombé Andrade, Jimmy; Soria López, Alberto
In this paper, we present a novel portable servomechanism control platform for educational purposes. The platform main features are: low cost, reliable and robust hardware, high‐speed USB interface, free open source software (FOSS), graphical interface modeling (via Scilab/XCos) and hard real‐time performance based on the Real‐Time Application Interface for Linux (RTAI). The platform is easy to interface with any computer and can be carried home by students, opening many new possibilities for practical assignments in control courses. We include application examples and student feedback regarding their experience during various workshops in which the system was demonstrated
A mathematical model for the optimal scheduling of smart home electrical loads
(World Scientific and Engineering Academy and Society, 2018-01-01) Moya Chavez, Francisco David; Da Silva, Luiz C. P.; Lopez A., Juan C.
This study develops a mathematical model for the optimal scheduling of controllable electrical loads in a smart home - MCELS. The goal of the MCELS is to minimize the total cost of the energy consumed by the smart house while decreasing the power supplied by the distribution network, still respecting requirements stablished by the costumer. To verify the MCELS results, a GRASP algorithm was used to compare both methodologies. A typical residential user in the area of Sao Paulo (Brazil), which has strong solar radiation, is established as a case study. The results show that the GRASP algorithm reduces the energy purchased from the network in approximatively 4%. Meanwhile, the MCELS provides a reduction of 6% on the energy used from the grid. This work also includes simulations where an electrical vehicle equipped with batteries of high storage capacity is recharged. Analysis of the results showed a superior performance of the MCELS if comparison with the GRASP algorithm, in five major aspects: a) lower use of the grid, b) reduction of electricity bill, c) higher use of renewable sources, d) reduction of demand peaks, and e) lower computation time
A new algorithm for detecting and correcting bad pixels in infrared images
(Ingenieria e Investigacion, 2010-07-22) Restrepo Girón, Andrés David; Loaiza Correa, Humberto
An image processing algorithm detects and replaces abnormal pixels individually, highlighting them amongst their neighbours in a sequence of thermal images without affecting overall texture, like classical filtering does. Bad pixels from manufacture or constant use of a CCD device in an IR camera are thus detected and replaced with a very good success rate, thereby reducing the risk of bad interpretation. Some thermal sequences from CFRP plates, taken by a Cincinnati Electronics InSb IR camera, were used for developing and testing this algorithm. The results were compared to a detailed list of bad pixels given by the manufacturer (about 70% coincidence). This work becomes relevant considering that the number of papers on this subject is low; most of them talk about astronomical image pre-processing. Moreover, thermographic non-destructive testing (TNDT) techniques are gaining popularity in Colombia at introductory levels in industrial sectors such as energy generation and transmission, sugar production and military aeronautics.
A note on the use of dolphins as bait in the artisanal fisheries off Bahía Solano, Chocó, Colombia
(Journal of Cetacean Research and Management, 2008) Avila, Isabel C.; García, Carolina; Bastidas, Juan Carlos
We evaluated dolphin hunting for bait in Bahía Solano, Chocó, Colombia, from July 2005 to April 2006. We interviewed 122 fishermen (18.2% of the registered fishermen in the zone) and obtained data from landings at a fishing company. Only fishermen using longlines (n=94; 37.3%) confirmed using dolphins for bait. One adult dolphin was reported to provide enough bait for two fishing bouts, capturing between 75 kg and 152 kg of fish. We could not obtain additional information about date, specific location or dolphin species, but the most probable captured species are Tursiops truncatus (common bottlenose dolphin) and Stenella attenuata (pantropical spotted dolphin), since these are the most commonly encountered species in coastal waters. A minimum of nine dolphins were reported killed during the study period (1 dolphin/month). Extrapolating these numbers to all fishermen using longlines in the region (250), an absolute minimum of 24 dolphins might have been taken during the study period (2.7 dolphins/month). Presumably many fishermen even while they also took dolphins, did not communicate this to the interviewers, considering dolphins are legally protected in Colombia. Fish species captured with dolphin bait include Brotula clarkae, Cephalopholis acanthistius, Epinephelus cifuentesi, Mustelus lunulatus and Lobotes pacificus.
A novel and low-complexity peak detection algorithm for heart rate estimation from low-amplitude photoplethysmographic (PPG) signals
(Taylor and Francis Ltd, 2019-03) Argüello Prada, Erick Javier; Serna Maldonado, Rafael Daniel
Low-amplitude PPG signals are more affected by noise contamination and other undesirable effects because the signal strength is comparable to noise power. Although several authors claim that decreases in the amplitude of the PPG wave should be addressed from signal acquisition and conditioning stages such decreases can also be associated with changes in the patient condition. In that instance, it is important to ensure continuous and reliable HR monitoring which, in turn, depends on how robust is the peak detection method. Numerous efforts have been made to develop algorithms for accurate PPG peak detection under high motion artefact conditions. However, little has been done regarding peak detection in low-amplitude PPG signals. In an attempt to address this issue, a novel and simple peak detection algorithm for PPG signals was proposed. Results show that our method could be a good contribution for robust strategies that can dynamically adapt their peak detection method to circumstances in which a decrease in the amplitude of the PPG signal is expected. Still, more extensive testing under a wide range of conditions (e.g. intensive physical exercise) is needed to perform a rigorous validation.
A search engine optimization recommender system
(CEUR-WS, 2019-09-19) Hoyos, Christian D.; Duque, Juan C.; Barco, Andres F.; Vareilles, Elise
Search Engine Optimization reefers to the process of improving the position of a given website in a web search engine results. This is typically done by adding a set of parameters and metadata to the hypertext files of the website. As nowadays the majority of the web-content creators are non-experts, automation of the search engine optimization process becomes a necessity. On this regard, this paper presents a recommender system to improve search engine optimization based on the site’s content and creator’s preferences. It exploits text analysis for labels and tags, artificial intelligence for deducing content intention and topics, and case-based reasoning for generating recommendations of parameters and metadata. Recommendations are given in natural language using a predefined set of sentences
A SSVEP-BCI setup based on Depth-of-Field
(Institute of Electrical and Electronics Engineers Inc., 2017-02-23) Cotrina, Anibal; Botti Benevides, Alessandro; Castillo Garcia, Javier; Botti Benevides, Alessander; Rojas Vigo, David; Ferreira, Andre; Bastos Filho, Teodiano Freire
In optical systems, the range of distance near the point of focus where objects are perceived sharply is referred as depth-of-field; objects outside this region are defocused and blurred. Furthermore, ophthalmology studies state that the amplitude and the latency of visual evoked potentials are affected by defocusing. In this context, this paper evaluates a novel setup for a steady-state visual evoked potential (SSVEP) brain-computer interface, in which two stimuli are presented together in the center of the user's field of view but at different distances ensuring that if one stimulus is focused on, the other one is non-focused, and vice versa. The evaluation was conducted with eight healthy subjects who were asked to focus on just one stimulus at a time. An average accuracy rate of 0.93 was achieved for a time window of 4 s by employing well know SSVEP detection methods. Results show that distinguishable SSVEP can be elicited by the focused stimulus regardless of the non-focused one is also present in the field of view. Finally, this approach allows users to send commands through a stimuli selection by focusing mechanism that does not demand neck, head, and/or eyeball movements.
Acoustic characteristics of vot in plosive consonants produced by parkinson’s patients
(Springer Science and Business Media Deutschland GmbH, 2020-09-01) Argüello Vélez, Patricia; Arias Vergara, Tomás; González Rátiva, María Claudia; Orozco Arroyave, Juan Rafael; Nöth, Elmar; Schuster, Maria Elke
Voice Onset Time (VOT) has been used as an acoustic measure for a better understanding of the impact of different motor speech disorders in speech production. The purpose of our paper is to present a methodology for the manual measuring of VOT in voiceless plosive sounds and to analyze its suitability to detect specific articulation problems in Parkinson’s disease (PD) patients. The experiments are performed with recordings of the diadochokinetic evaluation which consists in the rapid repetition of the syllables /pa-ta-ka/. A total of 50 PD patients and 50 healthy speakers (HC) participated in this study. Manual measurements include VOT values and also duration of the closure phase, duration of the consonant, and the maximum spectral energy during the burst phase. Results indicate that the methodology is consistent and allows the automatic classification between PD patients and healthy speakers with accuracies of up to 77% .
Acquisition Protocol and Comparison of Myoelectric Signals of the Muscles Innervated by the Ulnar, Radial and Medial Nerves for a Hand Orthoses
(Springer, 2020-03-03) Bermeo Varón, Leonardo A.; Villarejo Mayor, John J.; Arcos, Edgar F.; Quiguanas, Diana M.; Bravo, Andrea A.; Perez Plaza, Vanessa
This paper proposes a protocol for obtaining surface myoelectric signals in muscles of the upper limb for characterization of hand movement patterns. To characterize the movement patterns, the magnitude of the signal from each muscle is compared, for eight movements: (i) flexion, (ii) extension, (iii) ulnar and (iv) radial deviation of the hand, (v) metacarpophalangeal flexion, (vi) metacarpophalangeal extension, (vii) opposition and (viii) adduction thumb. Specific points were considered to acquire the signals from muscles innervated by the radial, medial and ulnar nerve, following the recommendations of the SENIAM project, in six intact people, using a myoelectric signal acquisition system. Seven protocols with recommendations for the location of sensors in the muscles were obtained, intended to establish combinations to reduce the number of sensors for future designs of assistive technologies, such as active orthoses. The suitable characteristic patterns for the hand movements studied allows the identification of a reduced set of sensors, considering the same eight movements. In this way, the functionality and rehabilitation processes of hand injuries are improved, facilitating the execution of activities of daily living.
Acute and subacute toxicity of Salvia scutellarioides in mice and rats
(Journal of Ethnopharmacology, 2007-01-19) Ramírez, Jorge H.; Palacios, Mauricio; Tamayo, Oscar; Jaramillo, Roberto; Gutiérrez, Oscar
The acute and subacute toxicity of the aqueous extract of Salvia scutellarioides (Lamiaceae) was studied in mice and rats. In the acute toxicity test, oral administration of 2 g/kg of Salvia scutellarioides produced neither mortality nor changes in behavior or any other physiological activities. In subacute toxicity studies, no mortality was observed when the two doses of 1 or 2 g/kg day of aqueous extract of Salvia scutellarioides extract were administered orally for a period of 28 days. In the blood chemistry analysis, no significant changes occurred, including glucose, creatinine, blood urea nitrogen (BUN), aspartate transaminase (AST), alanine transaminase (ALT), potassium, sodium, chloride, calcium, phosphorus, conjugated billirrubin, total billirrubin, total cholesterol, high density lipoprotein (HDL), triglycerides, total protein, albumin, prothrombin time (PT) and thromboplastin partial time (PTT) of both sexes. Hematological analysis showed no differences in any of the parameters examined (WBC count, platelet and hemoglobin estimation) in either the control or treated group of both sexes. The urinalysis was negative for glucose, ketonic bodies, casts, red blood cells, and albumin in the control and treatment groups. There were no significant differences in the body and organ weights between controls and treated animals of both sexes. Pathologically, neither gross abnormalities nor histopathological changes were observed.
Acute coronary syndromes: Epidemiology and diagnosis
(Salud Uninorte, 2009) Cassiani Miranda, Carlos Arturo; Cabrera G, Armando
Acute coronary syndromes are a major public health problem. Acute coronary syndrome (ACS) includes acute myocardial infarction (AMI), with or without ST elevation and unstable angina. The annual incidence of AMI is 565,000 new events and 300,000 recurrent attacks each year. Risk factors for heart disease (CD) ischemic include: smoking, high levels of serum lipids, hypertension, diabetes mellitus, morbid obesity, sedentary lifestyle, low daily consumption of fruits and vegetables, alcohol problem and psychosocial index. The initial assessment of an ACS should focus on the discomfort chest, signs and symptoms and risk factors for ACS. Biological markers of myocardial injury today are not essential to decide the initial management but have contributed to an increased sensitivity of diagnosis and provide data for the prognosis of patients.
Adherence to the strategy of the gold minute in the partners room of an institution level II of Cali (Colombia), year 2017: Cross sectional study
(Federacion Colombiana de Asociaciones de Obstetricia y Ginecologia (FECOLSOG), 2019-08-28) Moreno Reyes, Sandra Patricia; Calvo Bolaños, Paola Andrea; Cruz Mosquera, Freiser Eceomo; Cubides Munévar, Ángela Mayerly; Estupiñán Pérez, Víctor Hugo
Objetivo: determinar la adherencia global y por componentes a la estrategia minuto de oro en médicos que atienden recién nacidos en una entidad de mediano nivel de complejidad. Materiales y métodos: estudio de corte transversal; se incluyeron recién nacidos vivos de partos vaginales espontáneos atendidos por médicos pediatras, ginecólogos o internos en sala de partos de un hospital universitario de la ciudad de Cali, Colombia, en el 2017. Se excluyeron fetos con malformaciones congénitas mayores, gemelares y con menos de 34 semanas de edad gestacional. Muestreo sistemático. Tamaño muestral: 150 recién nacidos. Se evaluaron las características basales de los recién nacidos y sus madres, y la adherencia a la estrategia minuto de oro y sus componentes. Se hizo análisis descriptivo. Resultados: la adherencia al minuto de oro en médicos pediatras fue del 65,6 % (IC 95 %: 53,8-78,4), en ginecobstetras, de 33,33 % (IC 95 %: 4,3-77,7), y en médicos internos, de 75,3 % (IC 95 %: 64,8-85,1). La menor frecuencia se dio en la colocación del gorro al recién nacido, 64,90 % (IC 95 %: 56,7-72,4), y poner al bebé piel a piel sobre la madre, 65 % (IC 95 %: 55,9-74,4); la mayor frecuencia se presentó en cubrir al recién nacido con paños calientes, 98,6 % (IC 95 %: 95,3-99,8), y la ventilación con presión positiva en los casos en los que no había respuesta a la estimulación inicial, 100 % (IC 95 %: 30-100). Conclusiones: los resultados obtenidos sobre el grado de adherencia de los profesionales sugieren la necesidad de realizar procesos continuos de educación y evaluación sobre la aplicación de esta estrategia de reconocida efectividad en las instituciones que ofrecen el servicio de atención de partos.
Aerobic exercise in patients with heart failure with and without ventricular dysfunction in a cardiac rehabilitation programme
(Elsevier B.V., 2019-03-27) Ávila-Valencia, Juan Carlos; Hurtado-Gutiérrez, Hugo; Benavides Córdoba, Vicente; Betancourt-Peña, J.
Objective: To establish the effects of aerobic exercise on the physical capacity and some physiological variables in patients with heart failure with ventricular dysfunction and those with heart failure and conserved ventricular function. Methods: A quasi-experimental study was conducted on 23 patients with heart failure that attended a cardiac rehabilitation programme in the city of Cali, Colombia. The patients were classified into 2 groups: LVEF < 40% (heart failure with ventricular dysfunction) and LVEF ≥ 40% (heart failure with conserved ventricular function). The following variables were recorded before and after: weight, body mass index, systolic –diastolic blood pressure, and aerobic capacity. The exercise was performed 3 times / week for 12 weeks, with strength training and aerobic exercise between 50% and 75% of the maximum heart rate or with the Borg scale modified for patients taking beta-blockers. The paired t test was used to establish changes between variables. A value of P<.05 was taken as statistically significant. Results: A total of 12 patients were placed in the group with heart failure and ventricular dysfunction and 11 in the group with heart failure and conserved ventricular function. The mean age was 60.1±9.8 and 58±12.4, respectively. The systolic blood pressure decreased by 13.7 mm Hg ± 4.1; P=.007, in the group with heart failure and conserved ventricular function, and 10.8 mmHg±3.4; P=.008, in the group with ventricular dysfunction. The aerobic capacity showed a statistically significant increase for both groups. Conclusions: Both groups had good adherence to the aerobic exercise, as they achieved a statistically significant improvement as regards the systolic blood pressure and aerobic capacity. © 2019 Sociedad Colombiana de Cardiología y Cirugía Cardiovascular
Agotamiento profesional en personal de enfermería y factores de riesgo psicosocial
(Sociedad Venezolana de Farmacologia y de Farmacologia Clinica y Terapeutica, 2019-12-01) Méndez Beltrán, Jenny; Botero Carvajal, Alejandro
Introducción: La salud de los profesionales de salud mejora la atención de los usuarios mientras que el desgaste laboral disminuye la calidad de la atención. El objetivo es describir los factores asociados al agotamiento profesional en personal de enfermería. Métodos: Se buscó en: Pubmed, Scopus, Elsevier y Science Direct, la población objeto fue personal de enfermería diagnosticada con síndrome de desgaste profesional (burnout). Resultados: El personal de enfermería se encuentra en riesgo de padecer síndrome de desgaste profesional. Las variables intralaborales estadísticamente significativas fueron: puesto de trabajo con labores de servicio al cliente, profesiones de ayuda, trabajar en Unidad de Cuidados intensivos, intimidación por parte de un residente, anuncio de defunción. Se identifican factores protectores como las emociones de compasión y satisfacción, practicar pasatiempos, vocación de trabajar en enfermería, mayor remuneración económica y liderazgo. Discusión: Se plantea la necesidad de implementar factores protectores en los programas de salud y seguridad en el trabajo dirigidos al personal de enfermería.
AKT-like as part of the cell survival signaling pathways of Trypanosoma cruzi and Trypanosoma brucei
(Universidad de Antioquia, 2019-07-15) Díez Mejía, Andrés Felipe; Varela Miranda, Rubén Eduardo; Pulido Muñoz, Sergio Andrés; Echeverry Gaitán, María Clara; Marín Villa, Marcel
Las quinasas han sido descritas como las proteínas encargadas de la emisión y transducción de señales en la célula, generando respuestas que van desde la regulación de la homeostasis celular, hasta el control de la respuesta a estímulos. Dada la importancia de estas proteínas, reportadas como esenciales, actualmente existen medicamentos basados en la inhibición de quinasas, los cuales se emplean en el tratamiento de patologías como el cáncer y cuyas investigaciones se han extrapolado a la búsqueda de alternativas quimioterapéuticas para combatir enfermedades como la leishmaniasis, la tripanosomiasis americana y la africana, encontrando a las proteínas de la vía de las PI3Ks como dianas prometedoras.
The Akt-like kinase of Leishmania panamensis: As a new molecular target for drug discovery
(Elsevier B.V., 2018-01-01) Tirado-Duarte, Didier; Marín-Villa, Marcel; Ochoa, Rodrigo; Blandón-Fuentes, Gustavo; Soares, Maurílio José; Robledo, Sara María; Varela-M, R. E.
The Akt-like kinase of Leishmania spp. is a cytoplasmic orthologous protein of the serine/threonine kinase B-PKB/human-Akt group, which is involved in the cellular survival of these parasites. By the application of a computational strategy we obtained two specific inhibitors of the Akt-like protein of L. panamensis (UBMC1 and UBMC4), which are predicted to bind specifically to the pleckstrin domain (PH) of the enzyme. We show that the Akt-like of Leishmania panamensis is phospho-activated in parasites under nutritional and thermic stress, this phosphorylation is blocked by the UBMC1 and UMBC2 and such inhibition leads to cell death. Amongst the effects caused by the inhibitors on the parasites we found high percentage of hypodiploidy and loss of mitochondrial membrane potential. Ultrastructural studies showed highly vacuolated cytoplasm, as well as shortening of the flagellum, loss of nuclear membrane integrity and DNA fragmentation. Altogether the presented results suggest that the cell death caused by UMBC1 and UMBC4 may be associated to an apoptosis-like process. The compounds present an inhibitory concentration (IC50) over intracellular amastigotes of L. panamensis of 9.2 ± 0.8 μM for UBMC1 and 4.6 ± 1.9 μM for UBMC4. The cytotoxic activity for UBMC1 and UBMC4 in human macrophages derived from monocytes (huMDM) was 29 ± 1.2 μM and >40 μM respectively. Our findings strongly support that the presented compounds can be plausible candidates as a new therapeutic alternative for the inhibition of specific kinases of the parasite. © 2017 The Authors

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