Co-operative University of Colombia

www.ucc.edu.co
Bogota, Colombia
SEARCH FILTERS
Time filter
Source Type

Aristizabal V.H.,Co-operative University of Colombia | Velez F.J.,Co-operative University of Colombia | Rueda E.,University of Antioquia | Gomez N.D.,Metropolitan Institute of Technology | Gomez J.A.,Jaime Isaza Cadavid Colombian Polytechnic
Optics Express | Year: 2016

Although experimental advances in the implementation and characterization of fiber speckle sensor have been reported, a suitable model to interpret the speckle-pattern variation under perturbation is desirable but very challenging to be developed due to the various factors influencing the speckle pattern. In this work, a new methodology based on the finite element method (FEM) for modeling and optimizing fiber specklegram sensors (FSSs) is proposed. The numerical method allows computational visualization and quantification, in near field, of changes of a step multi-mode fiber (SMMF) specklegram, due to the application of a uniformly distributed force line (UDFL). In turn, the local modifications of the fiber speckle produce changes in the optical power captured by a step single-mode fiber (SSMF) located just at the output end of the SMMF, causing a filtering effect that explains the operation of the FSSs. For each external force, the stress distribution and the propagations modes supported by the SMMF are calculated numerically by means of FEM. Then, those modes are vectorially superposed to reconstruct each perturbed fiber specklegram. Finally, the performance of the sensing mechanism is evaluated for different radius of the filtering SSMF and force-gauges, what evidences design criteria for these kinds of measuring systems. Results are in agreement with those theoretical and experimental ones previously reported. © 2016 Optical Society of America.


Delgado D.R.,Co-operative University of Colombia | Pena M.A.,University of Alcalá | Martinez F.,National University of Colombia | Jouyban A.,Tabriz University of Medical Sciences | Acree W.E.,University of North Texas
Pharmaceutical Sciences | Year: 2016

Background: Dissolution thermodynamic quantities of sulfapyridine (SP) have been reported in the literature for aqueous alcoholic mixtures. Nevertheless, no attempts to evaluate the preferential solvation of this drug in this binary system, have been reported. In this way, the inverse Kirkwood-Buff integrals (IKBI) were used to evaluate this behavior in solution. Methods: Solubility data for SP dissolved in binary ethanol (EtOH) + water mixtures at various temperatures were mathematically represented using the Jouyban-Acree (J-A) model. The preferential solvation parameters of SP by EtOH (δx1,3) in EtOH + water mixtures were obtained from some thermodynamic properties of the mixtures by means of the IKBI method. Results: Solubility of SP in EtOH + water mixtures is adequately described by the J-A model in second order. Moreover, SP is sensitive to specific solvation effects, so the δx1,3 values are negative in water-rich and EtOH-rich mixtures indicating preferential solvation by water in these mixtures. By contrary, δx1,3 values are positive in the range 0.24 < x1 < 0.53 indicating preferential solvation by EtOH in these mixtures. Conclusion: It can be assumed that in water-rich mixtures the hydrophobic hydration around the aromatic rings plays a relevant role in the solvation. The higher drug solvation by EtOH in mixtures of similar solvent proportions could be due to polarity effects. Moreover, in EtOH + water mixtures SP could be acting as a Lewis acid with the EtOH molecules and in EtOH-rich mixtures the drug could be acting as a Lewis base with water molecules. ©2016 The Authors.


Estrada-Gomez S.,University of Antioquia | Vargas Munoz L.J.,University of Antioquia | Quintana Castillo J.C.,Co-operative University of Colombia
Toxicon | Year: 2013

We report the first studies of characterization and extraction of the Pamphobeteus aff. nigricolor (Pocock, 1901) (Aranae:Theraphosidae) venom done in Colombia using the electro-stimulation technique previous anesthesia with isofluorane. After each extraction process, a low viscosity, colorless venom was obtained. This venom showed a 1.01 mg/μl density and a pH of 5. The humidity percentage did not show a significance difference between males and females (P > 0.05) with a general media of 77.49 ± 1.74%. In all cases the venom yielded was variable between males and females, with a media of 22.45 ± 5.17 mg (wet weight) and 4.58 ± 0.94 mg (dry weigh), obtaining larger amounts in females, 28.34 ± 7.49 mg and 5.69 ± 1.36 (wet and dry weight respectively). Venom showed a hemolytic activity dependent of enzymatic active phospholipase and neither coagulant nor proteolytic activities were observed. Electrophoretic profile showed a main protein content with a molecular mass below 14 kDa. RP-HPLC venom profile revealed a difference among male and female venom's content where 17 and 21 main fractions were obtained respectively. Three peptides, Theraphotoxin-Pn1a, Theraphotoxin-Pn1b and Theraphotoxin-Pn2a, were identified using HPLC-nESI-MS/MS. These peptides showed a high identity with other peptides found on Theraphosides which are proved to affect voltage-gated calcium channels. © 2013 Elsevier Ltd. All rights reserved.


Patino A.C.,University of Antioquia | Pereanez J.A.,University of Antioquia | Pereanez J.A.,Co-operative University of Colombia | Gutierrez J.M.,University of Costa Rica | Rucavado A.,University of Costa Rica
Toxicon | Year: 2013

Two clotting serine proteinases, named Cdc SI and Cdc SII, were isolated and characterized for the first time from Colombian Crotalus durissus cumanensis snake venom. The enzymes were purified using two chromatographic steps: molecular exclusion on Sephacryl S-200 and RP-HPLC on C8 Column. The molecular masses of the proteins, determined by MALDI-TOF mass spectrometry, were 28,561.4 and 28,799.2 Da for Cdc SI and Cdc SII, respectively. The aim of the present study was to evaluate enzymatic, coagulant and toxic properties of the two enzymes. The serine proteinases hydrolyzed specific chromogenic substrate (BaPNA) and exhibited a Michaelis-Menten behavior. Cdc SI had Vmax of 0.038 ± 0.003 nmol/min and KM of 0.034 ± 0.017 mM, while Cdc SII displayed values of Vmax of 0.267 ± 0.011 nmol/min and KM of 0.145 ± 0.023 mM. N-terminal sequences were VIGGDEXNIN and VIGGDICNINEHNFLVALYE for Cdc SI and Cdc SII, respectively. Molecular masses, N-terminal sequences, inhibition assays, and enzymatic profile suggest that Cdc SI and Cdc SII belong to the family of snake venom thrombin-like enzymes. These serine proteinases differed in their clotting activity on human plasma, showing a minimum coagulant dose of 25 μg and 0.571 μg for Cdc SI and Cdc SII, respectively. Enzymes also showed coagulant activity on bovine fibrinogen and degraded chain α of this protein. Toxins lack hemorrhagic and myotoxic activities, but are capable to induce defibrin(ogen)ation, moderate edema, and an increase in vascular permeability. These serine proteinases may contribute indirectly to the local hemorrhage induced by metalloproteinases, by causing blood clotting disturbances, and might also contribute to cardiovascular alterations characteristic of patients envenomed by C. d. cumanensis in Colombia. © 2012 Elsevier Ltd.


Salamanca C.A.,Co-operative University of Colombia | Bentez M.J.,Co-operative University of Colombia
Revista Electronica de Veterinaria | Year: 2012

Milk production and lactation length are parameters to find out the amount of milk produced by cows and per farm. There were compared by the farm milk production variables: days of lactation (DILAC), daily milk (KDIA) and total milk per lactation (KTOT) of 95 lactating crossbred cows from five farms in the town of Arauca. Linear procedures there were used GLM of SAS. Comparison of means was done by Tukey test. The estimated average was (KTOT) 521.1 ± 254.8 kilos with a variation of 42.0%, the mean for DILAC was 253.4 ± 85.7 days with 29.1% of variation. The farm was a significant variation factor (p < 0.01) for features and KTOT KDIA and did not affect (p < 0.05) the DILAC. The year of birth of the offspring had a significant effect (p < 0.01) on DILAC, had no effect (p < 0.05) on daily production and approached the 5% probability (p = 0.06) in total. The parity only affected significantly (p < 0.05) total milk production, while the breed of cow on the farm affected (p < 0.05) days in milk production and total milk (p < 0.01). We conclude that environmental factors analyzed: farm, year of birth and parity and the effect of racial group affected the milk production parameters studied.


The following article shows the process of building and validating a framework for the management of consistencies in class diagrams in UML, operating specifically on class diagrams, through the application of transformation rules, using both graph grammar and OCL (Object Constraint Language). The proposed framework, after examining the techniques of consistency management, operates on a class diagram, since this constitutes a structural diagram. This is even more important when modeling, and it facilitates the application of rules based on the treated techniques, thus contributing to provide the community of analysts and modelers with a support tool for the refinement and quality improvement of the diagrams. It also operates on a typical case of application to show the tool's advantages, thus making it easier to comprehend and understand. © The authors; licensee Universidad Nacional de Colombia.


Diaz L.G.,Co-operative University of Colombia
International Journal of Pavement Research and Technology | Year: 2016

Cold Mix Asphalt (CMA) is commonly used in lieu of typical Hot Mix Asphalt (HMA) for localized pavement patching due to the quantities, intermittent locations and times when repairs need to be executed. The objective of this investigation was to evaluate the resistance of CMA to accumulate permanent deformation under cyclic loading, and to present an alternative to assess stability potential from a portable device. Considering CMA is at its weakest state right after placement, and that its resistance to creep improves with curing, the study focused on evaluating the rutting performance of uncured CMA materials at different compaction levels in the laboratory by means of parameters b and FN from a Modified Cyclic Creep Test (MCCT) and by their resistance to penetration with a Light Cone Penetrometer (LCP), defined by the LCP penetration rate (LPR). Based on the experimental results, acceptable laboratory stability can be expected when values below 0.5 με/load and over 1000 load cycles are observed for b and FN, respectively. Considering the potential use of the LCP as a field-friendly quality control tool, models to estimate parameters b and FN from the MCCT as a function of LPR and other CMA characteristics were developed using Multiple Linear Regression Analysis (MLRA). The results suggest that when LPR values are limited to 0.50 mm/blow, CMA materials can be expected to show acceptable stability levels. © 2016.


Hernandez J.C.,Co-operative University of Colombia | Latz E.,University of Massachusetts Medical School | Latz E.,University of Bonn | Urcuqui-Inchima S.,University of Antioquia
Intervirology | Year: 2013

Background/Aims: Inflammasomes are multimolecular complexes that regulate caspase-1. They act as sensors for endogenous and exogenous signals, and mediate the processing of pro-IL-1β into its secreted, biologically active form. The NLRP3 inflammasome and IL-1β are particularly interesting because they are required for efficient control of viral infections. Indeed, HIV-1 induces expression of NLRP3 and IL-1β in healthy controls, but not in HIV-1-infected patients. Here we evaluate whether HIV-1 can induce activation of the NLRP3 inflammasome. Methods: Human primary monocyte-derived macrophages were infected with HIV-1 in the absence or presence of classical NLRP3 inflammasome activators, and IL-1β release was assessed by ELISA. Results: HIV-1 initiates the priming signal for NLRP3 inflammasome activation through the NF-κB-associated pathway in human primary monocyte-derived macrophages. Furthermore, priming of NLRP3 activation in response to HIV-1 was independent of the viral envelope, since similar results were observed with HIV-1 and pseudotyped HIV-1 lacking the env gene. Conclusion: Our findings suggest that HIV-1 infection promotes IL-1β secretion by inducing the first signal for NLRP3 inflammasome activation, a phenomenon that may contribute to AIDS progression. Copyright © 2013 S. Karger AG, Basel.


Objective Describing the Emberá-Chamí Indians' traditional medical system (Caldas Department, Colombia). Methods This was an ethnographic study which involved 4 traditional doctors, 2 midwives, 3 healers, a faith-healer (medicine man) and 10 community members who were selected by theoretical sampling. Interviews, field diaries and participant observation were used in line with credibility, auditability and transferability criteria, and category saturation and methodological and theoretical triangulation. Results Traditional medicine, health, disease and healing were conceptualised, describing the system's therapeutic resources, links with biomedicine, spiritual domain components, the relevance of the Guardians and holy sites, the major rituals and roles of family, native physiotherapists, healers, medicine men/women, midwives and traditional faith-healing doctors. Conclusion Indigenous people have valuable knowledge about practices involving the body, social interactions, coexistence with nature and spiritual beings which is based on harmony and integral worldviews.


With the purpose of measuring production yields at a meat production farm, technical records for 597 crossbred Zebu steers fattened were examined in the period from 2006 to 2009 in municipality of Tame, in the department of Arauca, Colombia. Indicators of average daily gain (ADG), efficiency of production (EP), meat yield (R), meat yield per year (kg / animal / year) and of meat yield per hectare per year (kg / ha / year) were calculated. The data was analyzed using descriptive statistics. Year 2009 showed the best performance for GDP and kg / day / year yield was shown in year 2009 with 905 g and 330.3 kg and the lowest R 70.2% R, however, it was offset by efficiency production of meat / animal / year (365,5 kg). Meat production per area with 375 kg / ha / year excelled in 2007. The EP showed similar production for all years. It is concluded that in each period there is a wide variation in production due to initial weight and environmental conditions of each year. © 2014,Instituto Nacional de Investigaciones Agricolas (INIA). All rights reserved.

Loading Co-operative University of Colombia collaborators
Loading Co-operative University of Colombia collaborators