Nuevo conocimiento - NAT

URI permanente para esta colecciónhttp://hdl.handle.net/10906/78210

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A ‘slow pace of life’ in Australian old-endemic passerine birds is not accompanied by low basal metabolic rates
(Springer Verlag, 2016-05-01) Buttemer, William A.
Life history theory suggests that species experiencing high extrinsic mortality rates allocate more resources toward reproduction relative to self-maintenance and reach maturity earlier (‘fast pace of life’) than those having greater life expectancy and reproducing at a lower rate (‘slow pace of life’). Among birds, many studies have shown that tropical species have a slower pace of life than temperate-breeding species. The pace of life has been hypothesized to affect metabolism and, as predicted, tropical birds have lower basal metabolic rates (BMR) than temperate-breeding birds. However, many temperate-breeding Australian passerines belong to lineages that evolved in Australia and share ‘slow’ life-history traits that are typical of tropical birds. We obtained BMR from 30 of these ‘old-endemics’ and ten sympatric species of more recently arrived passerine lineages (derived from Afro-Asian origins or introduced by Europeans) with ‘faster’ life histories. The BMR of ‘slow’ temperate-breeding old-endemics was indistinguishable from that of new-arrivals and was not lower than the BMR of ‘fast’ temperate-breeding non-Australian passerines. Old-endemics had substantially smaller clutches and longer maximal life spans in the wild than new arrivals, but neither clutch size nor maximum life span was correlated with BMR. Our results suggest that low BMR in tropical birds is not functionally linked to their ‘slow pace of life’ and instead may be a consequence of differences in annual thermal conditions experienced by tropical versus temperate species. © 2016, Springer-Verlag Berlin Heidelberg.
Activity of (2E)-3-(2, 3-dimetoxifenil)-1-(4-metilfenil) prop-2-en-1-ona in the presence of poli(maleic acid-co-2-vinyl-pyrrolidone) on a β-lactamase producing clinical isolate of Staphylococcus aureus
(Universidad de Antioquia, 2012-01-01) Salamanca Mejía, Constaín Hugo
Due to the current problem of resistance to b-lactam antibiotics, it has become necessary, in search of a solution, to work with new molecules with pharmacological potential, and to use novel polymeric systems as matrices or pharmaceutical excipients. Objective: To evaluate the antibiotic activity of ampicillin combined with a synthetic chalcone-type compound, the (2E)-3-(2,3-dimethoxyphenyl)-1-(4- methylphenyl) prop-2-en-1-one, on a clinical isolate of penicillin-resistant Staphylococcus aureus in the presence of a water soluble polymer matrix known as poly(maleic acid-co-2-vinyl-pyrrolidone). Materials and methods: The synthetic compound and the polymeric matrix were obtained by previously described methods. Tests for antibiotic activity against the strain of penicillin-resistant Staphylococcus aureus were done by the broth dilution technique which provided the minimal inhibitory concentrations of the compounds tested. Results: The chalcone-ampicillin mix shows lesser antibiotic effect than the ampicillin-sulbactam used as referent. However, when such mix is combined with the polymer matrix, antibiotic activity significantly increases as evidenced by decrease in the minimal inhibitory concentration with respect to the ampicillin-sulbactam referent.
Acyclic diene metathesis polymerization: History, methods and applications
(Elsevier Ltd, 2017-06-01) Caire da Silva, Lucas
Acyclic Diene Metathesis (ADMET) polymerization was established decades ago and has since developed into a robust and reliable technique. A wide range of different, new materials exhibiting unique properties has been produced via ADMET polymerization since its development. This versatile technique allows, through the right combination of monomer design and choice of catalyst, the synthesis of various functional polymers in addition to a precise control over primary structure. Systematic studies on precise ADMET polymers have greatly contributed to a better understanding of how branch identity and its distribution along the polymer backbone affect the thermal/electronic properties, crystallization, molecular dynamics and morphology of different materials. This article presents an extensive review of how ADMET started, the mechanism that underlies the structural features of ADMET polymers and the different strategies and techniques that have been developed over the years to overcome common synthetic challenges. Monomer synthesis methods are also discussed in detail, providing an important overview of the limitations and advantages of using ADMET as a polymerization technique. Many examples are given of functional ADMET polymers that have been developed by research groups all over the world. © 2016 Elsevier B.V.
Los bosques secos del Valle del Cauca, Colombia: una aproximación a su flora actual
(Universidad Nacional de Colombia, 2012-12-01) Vargas, William Gerardo
From the plant collections and personal records made by the author in the dry forests of Valle del Cauca between 1992 and 2012, presents an analysis of current status of the flora and dry forests in the region. After reviewing nearly 12.000 records of herbal plants Valley dry forests and explored the key areas, the current membership consists of approximately 1.300 species of vascular plants, of which 255 correspond to trees. Epiphytes and trees are the groups most affected by deforestation, and on which it is possible to better understand how they have impacted natural ecosystems in Valle del Cauca, is also on them that can more effectively focus conservation actions that generate a positive impact. It also presents a list of 936 plant species of the dry forests, the largest so far presented, and which contains information on habits, distribution, abundance, threats, habitat and type of dispersion. This work aims to contribute to knowledge and design of strategies for conservation and restoration of these ecosystems.
Breeding biology and egg temperatures of Black-faced Brush-finches (Atlapetes melanolaemus), Neotropical montane songbirds
(Blackwell Publishing Inc., 2016-01-01) Londoño Guerrero, Gustavo Adolfo
Black-faced Brush-finches (Atlapetes melanolaemus) are a common species restricted to the Andes of southern Peru and western Bolivia. We provide the first description of the breeding biology of this Neotropical montane passerine, including an analysis of incubation behavior and egg temperatures. We found 47 nests during seven breeding seasons (2007–2013) near Manu National Park, Peru. Nesting occurred in late July, peaked in early October, and continued into early December. All clutches consisted of two eggs, and the mean incubation period (14.8 ± 0.2 d) was relatively short compared with related species. Nest attentiveness increased and the length of foraging trips decreased as the incubation period progressed, but the number of foraging trips/day was constant. Egg temperatures when birds returned to incubate were negatively correlated with the duration of incubation bouts, whereas ambient temperature and the duration of the previous incubation bout were positively correlated with the duration of foraging bouts. Eggs were consistently incubated at lower temperatures (24-h mean = 32.1°C) than other Neotropical and temperate species. When incubating birds left nests, egg temperature dropped below the physiological zero temperature (24–27°C) in ~11 min. Nestlings had a high growth rate (k = 0.60) and a long nestling period (mean = 13.8 d) compared with related Neotropical and temperate emberizines. By showing that the duration of incubation and foraging bouts are affected by different intrinsic and extrinsic factors, we provide evidence that incubation is not only temporally dynamic, but also finely modifiable. Our results also suggest that embryos of high-elevation Neotropical songbirds are particularly resistant to ambient temperature extremes and low incubation temperatures, emphasizing the need for more studies of egg thermoregulation and its consequences for development, growth, and survival. We conclude that closely related species, both on different continents and at the same locations, may differ in parental care strategies and development regimes, cautioning against broad generalizations regarding species groups or geographic areas. © 2016 Association of Field Ornithologists
First nesting account and breeding biology of "gould's Inca" (Coeligena torquata omissa) in Manu National Park, Peru
(Wilson Ornithological Society, 2016-09-03) Londoño, Gustavo Adolfo
We present the first detailed nesting biology information for the highland Andean hummingbird Gould's Inca (Coeligena torquata omissa) at 2,200-3,000 m in Manu National Park, SE Peru. We found nine mossy cup-shaped nests lined with red fern scales containing nestlings or 1-2 synchronously hatching eggs. We obtained 17 days of internal nest temperatures from one nest, which exhibited wide circadian variation (range = 14.9-36.2 °C). We show that C. t. omissa meets the challenges of life and incubation at high altitudes by undertaking numerous (20.3 ± 0.4 trips/morning, range = 14-27) and short morning off-bouts (5.2 ± 0.2 min, range = 1-24 min). In the morning, the focal bird warmed the nest 1.7 times faster than in the afternoon where incubation bouts are long (17.8 ± 0.6 min, range = 4-56) and less frequent (10.2 ± 0.3 trips/afternoon). Incubation off-bout frequency and durations were not influenced by external temperature, suggesting strong nest insulation. On-bout durations increased with external temperature most strongly in the cold mornings. Short off-bouts and long on-bouts yielded high attentiveness (70.2%). One nestling fledged after 23 days. The eggs measured 15.2 ± 0.4 mm by 9.3 ± 0.3 mm and weighed 0.75 ± 0.03 g (n = 12). The small mossy cup nest was 81.9 ± 5.9 mm by 75.8 ± 4.4 mm wide and 73.1 ± 6.7 mm high. The inner cup was 45.7 ± 3.0 mm long by 45.6 ± 4.1 mm wide and 30.9 ± 2.5 mm deep (n = 8). Compared to C. t. torquata, we found a smaller egg width, higher nest placement and different nest substrate, but confirmed similarities in many aspects of nesting strategies.
Generalist Species Have a Central Role In a Highly Diverse Plant-Frugivore Network
(Blackwell Publishing Ltd, 2016-05-01) Kattán, Gustavo H.
Analysis of plant-frugivore interactions provides a quantitative framework for integrating community structure and ecosystem function in terms of how the roles and attributes of individual species contribute to network structure and resilience. In this study, we used centrality metrics to rank and detect the most important species in a mutualistic network of fruit-eating birds and plants in a cloud forest in the Colombian Andes. We identified a central core of ten bird and seven plant species in a network of 135 species that perform dual roles as local hubs and connectors. The birds were mostly large forest frugivores, such as cracids, cotingas, and toucans, which consume fruits of all sizes. The plants were species of intermediate successional stages with small- to medium-sized seeds that persist in mature forest or forest borders (e.g., Miconia, Cecropia, Ficus). We found the resilience of our network depends on super-generalist species, because their elimination makes the network more prone to disassemble than random extinctions, potentially disrupting seed-dispersal processes. At our study site, extirpation of large frugivores has already been documented, and if this continues, the network might collapse despite its high diversity. Our results suggest that generalist species play critical roles in ecosystem function and should be incorporated into conservation and monitoring programs. © 2016 The Association for Tropical Biology and Conservation.
Physicochemical characterization of in situ drug-polymer nanocomplex formed between zwitterionic drug and ionomeric material in aqueous solution
(Elsevier, 2017-03-01) Villada, Juan D.
Biocompatible polymeric materials with the potential to form functional structures, in association with different therapeutic molecules, in physiological media, represent a great potential for biological and pharmaceutical applications. Therefore, here the formation of a nano-complex between a synthetic cationic polymer and model drug (ampicillin trihydrate) was studied. The formed complex was characterized by size and zeta potential measurements, using dynamic light scattering and capillary electrophoresis. Moreover, the chemical and thermodynamically stability of these complexes were studied. The ionomeric material, here referred as EuCl, was obtained by equimolar reaction between Eudragit E and HCl. The structural characterization was carried out by potentiometric titration, FTIR spectroscopy, and DSC. The effect of pH, time, polymer concentration and ampicillin/polymer molar ratio over the hydrodynamic diameter and zeta potential were established
Solar photo-Fenton optimisation in treating carbofuran-contaminated water
(Universidad Nacional de Colombia, 2012-01-01) Mendoza Marín, Claudia
Box-Benkhen design response-surface methodology was developed to optimise photo-Fenton degradation of carbofuran (C12H15NO3) by using a compound parabolic collector pilot plant. The four variables considered in Box-Benkhen design model included carbofuran degradation percentage, initial carbofuran concentration, hydrogen peroxide [H2O2] concentration and iron [Fe2+] concentration. Degradation was monitored by using total organic carbon concentration and high-performance liquid chromatography. A 93.2 mg l-1 carbofuran concentration was completely degraded in t30W = 15 min with 17.1 mg l-1 Fe2+ and 121.6 mg l-1 H2O2. Photo-Fenton degradation led to 76.7% mineralisation. Biodegradability during optimisation was evaluated by using the BOD5/COD ratio; this value increased from 0.04 at the beginning of the process to 0.52 in t30W = 20 min, thereby showing the effectiveness of using biological treatments
Spatial modeling of cutaneous leishmaniasis in the Andean region of Colombia
(Fundaco Oswaldo Cruz, 2016-07-01) Pérez-Flórez, Mauricio
The objective of this research was to identify environmental risk factors for cutaneous leishmaniasis (CL) in Colombia and map high-risk municipalities. The study area was the Colombian Andean region, comprising 715 rural and urban municipalities. We used 10 years of CL surveillance: 2000-2009. We used spatial-temporal analysis - conditional autoregressive Poisson random effects modelling - in a Bayesian framework to model the dependence of municipality-level incidence on land use, climate, elevation and population density. Bivariable spatial analysis identified rainforests, forests and secondary vegetation, temperature, and annual precipitation as positively associated with CL incidence. By contrast, livestock agroecosystems and temperature seasonality were negatively associated. Multivariable analysis identified land use - rainforests and agro-livestock - and climate - temperature, rainfall and temperature seasonality - as best predictors of CL. We conclude that climate and land use can be used to identify areas at high risk of CL and that this approach is potentially applicable elsewhere in Latin America.
Synanthropic Cockroaches (Blattidae: Periplaneta spp.) Harbor Pathogenic Leptospira in Colombia
(Entomological Society of America, 2016-06-01) Bonilla, Álvaro
Leptospirosis cases in Colombia are typically linked to peridomestic rodents; however, empirical data suggest that Leptospira-infected patients with no apparent exposure to these reservoirs are common. Cockroaches (Periplaneta spp.) have equal or greater interaction with humans than rodents, yet their potential role as carriers of Leptospira has not been assessed. We determined if pathogenic Leptospira is harbored by Periplaneta spp. in Cali (Colombia) and the variables influencing this relationship. Fifty-nine cockroaches were captured from seven sites and DNA was extracted from the body surface and digestive tract for a multiplex polymerase chain reaction, targeting genes secY and flaB. Logistic regression models and proportion tests showed a higher likelihood for Leptospira to be isolated from body surfaces (P>0.001) and from individuals inside houses (six times more likely). These findings are the first to demonstrate an association between Periplaneta spp. and Leptospira, suggesting the need to investigate the potential for cockroaches to serve as reservoirs or transport hosts for Leptospira.
Tunable polyesterification of xylitol: from linear to crosslinked structures
(John Wiley and Sons Ltd, 2017-04-01) Benitez, Ricardo
The copolymerization by condensation chemistry of succinic acid and xylitol, a byproduct from the sugarcane and alcohol industry, is reported. Two methodologies were studied concerning succinic acid, with and without carboxylic acid activation, yielding crosslinked and linear low molecular weight polymers, respectively. All polymerizations were carried out at reaction times in the range from 36 to 80 h, with a molar mass ratio of 1:1 and 1:3. Linear and crosslinked polyesters were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, DSC and TGA, and structural characterization was carried out by Fourier transform infrared spectroscopy and NMR. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry

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Examinando Nuevo conocimiento - NAT por Materia "Biodiversity conservation"