Determination of biosorption mechanism in biomass of agave, using spectroscopic and microscopic techniques for the purification of contaminated water

[Abstract] Lead (Pb2+) and copper (Cu2+) are polluting metals due to their toxicity; however, the extraction of these metals is essential for economic development, so it is important to look for efficient and low-cost alternatives that can remove heavy metals from the various bodies of water. One of the alternatives used in this work is biosorption, for which an agroindustrial waste (epidermis from Agave atrovirens) was used to evaluate the affinity of removal of lead and copper in aqueous solutions; in addition, spectroscopy and microscopy techniques were used to elucidate and corroborate the removal and affinity capacity of the agave epidermis for both metals studied. The optimal pH value for the removal of both metals was 3. The adsorption isotherms yielded a qmax of 25.7 and 8.6 mg/g for lead and copper, respectively. Adjusting to the Langmuir-Freundlich model, the adsorption kinetics were pseudo-second order, and it was found that the equilibrium time was at 140 min. The spectroscopy and microscopy analyses corroborated the affinity between metals and functional groups of the agave, as well as with the elemental analysis, which reported 17.38% of lead and 4.25% of copper.[Resumen] El plomo (Pb2+) y el cobre (Cu2+) son metales contaminantes debido a su toxicidad; sin embargo, la extracción de estos metales es indispensable para el desarrollo económico, por lo que es importante buscar alternativas eficientes y de bajo costo que puedan remover metales pesados de los diversos cuerpos de agua. Una de las alternativas utilizadas en este trabajo es la biosorción, para la cual se utilizó un residuo agroindustrial (epidermis de Agave atrovirens), para evaluar la afinidad de remoción del plomo y cobre en soluciones acuosas; adicionalmente, se emplearon técnicas de espesctroscopía y microscopía que permitieron elucidar y corroborar la capacidad de remoción y afinidad que tuvo la epidermis de A. atrovirens para ambos metales estudiados. El valor óptimo de pH para la remoción de ambos metales fue 3. Las isotermas de adsorción arrojaron una qmax de 25.7 y 8.6 mg/g para el plomo y cobre, respectivamente. Ajustando al modelo de Langmuir-Freundlich, las cinéticas de adsorción resultaron de pseudo-segundo orden, se encontró que el tiempo de equilibrio es a los 140 min. El análisis espectroscópico y microscópico, corroboró la afinidad entre metales y grupos funcionales del agave, así como con el análisis elemental, el cual reportó 17.38% de plomo y 4.25% de cobre

The Mating System of the Wild-to-Domesticated Complex of Gossypium hirsutum L. Is Mixed

The domestication syndrome of many plants includes changes in their mating systems. The evolution of the latter is shaped by ecological and genetic factors that are particular to an area. Thus, the reproductive biology of wild relatives must be studied in their natural distribution to understand the mating system of a crop species as a whole. Gossypium hirsutum (upland cotton) includes both domesticated varieties and wild populations of the same species. Most studies on mating systems describe cultivated cotton as self-pollinated, while studies on pollen dispersal report outcrossing; however, the mating system of upland cotton has not been described as mixed and little is known about its wild relatives. In this study we selected two wild metapopulations for comparison with domesticated plants and one metapopulation with evidence of recent gene flow between wild relatives and the crop to evaluate the mating system of cotton’s wild-to-domesticated complex. Using classic reproductive biology methods, our data demonstrate that upland cotton presents a mixed mating system throughout the complex. Given cotton’s capacity for outcrossing, differences caused by the domestication process in cultivated individuals can have consequences for its wild relatives. This characterization of the diversity of the wild relatives in their natural distribution, as well as their interactions with the crop, will be useful to design and implement adequate strategies for conservation and biosecurity

Scoping methodology to asses induced vibration by railway traffic in buildings

This work presents a scoping model to predict ground-borne railway vibration levels within buildings considering soil-structure interaction (SSI). It can predict the response of arbitrarily complex buildings in a fraction of the time typically required to analyse a complex SSI problem, and thus provides a practical tool to rapidly analyse the vibration response of numerous structures near railway lines. The tool is designed for use in cases where the ground-borne vibration is known, and thus can be used as model input. Therefore in practice, for the case of a new line, the ground motion can be computed numerically, or alternatively, for the case of new buildings to be constructed near an existing line, it can be recorded directly (e.g. using accelerometers) and used as model input. To achieve these large reductions in computational time, the model discretises the ground-borne vibration in the free field into a frequency range corresponding to the modes that characterize the dynamic building response. After the ground-borne response spectra that corresponds with the incident wave field is estimated, structural vibration levels are computed using modal superposition, thus avoiding intensive soil-structure interaction computations. The model is validated using a SSI problem and by comparing results against a more complex finite element-boundary element model. Finally, the new scoping model is then used to analyse structural-borne vibration. The results show that the scoping model provides a powerful tool for use during the early design stages of a railway system when a large number of structures require analysis

Exploring the Design of Highly Energy Efficient Forestry Cranes using Gravity Compensation

Although most mechanized forestry work relies heavily on cranes for handling logs along the supply chain, there has been little research on how to improve cranes design. In addition, the available research has mainly focused on improving current designs, so there is a lack of application of modern methods for designing cranes with improved efficiency. This paper analyzes how a mechanical engineering design method, known as gravity compensation, can be used to make a new generation of highly energy efficient forestry cranes. To introduce this design approach, a standard forwarder crane with two booms is used as a model system on which to apply gravity compensation concepts. The design methodology follows a procedure based on physics and mathematical optimization, with the objective of minimizing the energy needed to move the crane by using gravity compensation via counterweights. To this end, we considered to minimize mechanical power, because this quantity relates to how fuel and hydraulic fluid are converted into mechanical motion. This analysis suggests that using gravity compensation could reduce energy consumption due to crane work by 27%, at the cost of increasing the crane total mass by 57%. Thus, the original crane mass of 559 kg increases to 879 kg after applying gravity compensation with counterweights. However, overall reductions in energy consumption would depend on both the crane work and the extraction distance. The greater the extraction distance, the lower the total savings. However, energy consumption savings of around 2% could be achieved even with an extraction distance of 1 km. From a design perspective, this study emphasized the need to consider gravity compensation in the design philosophy of forestry cranes, not only for its ability to minimize energy consumption, but also due to all the inherited properties it provides. This initial study concludes that designing cranes with a combination of gravity compensation concepts could yield a new generation of highly energy efficient cranes with energy savings exceeding those reported here

Effect of the inclusion of herbal phosphatidylcholine on palatability, digestibility and metabolisable energy of the diet in dogs

This study aimed to evaluate the palatability, nutrient digestibility, metabolisable energy (ME) and faecal characteristics of diets in dogs fed increasing levels of herbal phosphatidylcholine (herbal mix) versus an unsupplemented diet (with only 377 mg choline provided by 1 kg food) or choline chloride1 (2000 mg choline/kg food) in 40 adult dogs. In experiment 1, a palatability test was conducted to make two pairwise comparisons: 0 versus 200; and 0 versus 400 mg/kg herbal mix. In experiment 2, a digestibility test was performed to evaluate herbal mix at 0, 200, 400 and 800 mg/kg and 2000 mg choline provided by choline chloride. Results from experiment 1 indicated that the dogs preferred diets containing herbal mix to the unsupplemented diet (P<0.05). In experiment 2, nutrient digestibility and faecal characteristics were not influenced by the treatment (P<0.059). The inclusion of 400 mg/kg of herbal mix increased the ME (quadratic effect, P<0.01). In conclusion, the results of this study indicate that the inclusion of a herbal mix rich in phosphatidylcholine (1.6%) and other methylated metabolites at 400 mg/kg can fully replace choline chloride in dog diets

Surface shape resonances in lamellar metallic gratings

The specular reflectivity of lamellar gratings of gold with grooves 0.5 microns wide separated by a distance of 3.5 microns was measured on the 2000 cm$^{-1}$ - 7000 cm$^{-1}$ spectral range for p-polarized light. For the first time, experimental evidence of the excitation of electromagnetic surface shape resonances for optical frequencies is given. In these resonances the electric field is highly localized inside the grooves and is almost zero in all other regions. For grooves of depth equal to 0.6 microns, we have analyzed one of these modes whose wavelength (3.3 microns) is much greater than the lateral dimension of the grooves.Comment: 4 pages (LaTex), 5 postscript figures, to be published in Physical Review Letter

A transfer function method to predict building vibration and its application to railway defects

This work presents a simplified method to evaluate building shaking due to arbitrary base excitations, and an example application to railway problems. The model requires minimal computational effort and can be applied to a wide range of footing shapes, thus making it attractive for scoping-type analysis. It uses the soil excitation spectrum at the building footing location as it’s input, and computes the building response at any arbitrary location within it’s 3D structure. To show an application of the model versatility, it is used to compute building response due to a variety of singular railway defects (e.g. switches/crossings). It is however suitable for more general applications including railway problems without defects. The approach is novel because current railway scoping models do not use soil-structure transfer functions combined with free-field response to estimate building vibration by railway defects. First the soil-structure interaction approach is outlined for both rigid and flexible footings. Then it is validated by comparing results against a comprehensive fully-coupled 3D FEM-BEM model. Finally, it is used to analyse the effect of a variety of variables related to railway defects on building response. Local track defects are shown to have a strong influence on building vibrations. Further, vibration levels close to the threshold of human comfort are found in buildings close to the railway line. Overall the new approach allows for the computation of building vibrations accounting for soil-structure interaction, floor amplification and the measured/computed free-field response due to railway traffic using minimal computational effort

CARACTERIZACIÓN DE LA CALIDAD FÍSICA DEL CAFÉ DE LOS MUNICIPIOS CAFETEROS DEL NORTE DE ANTIOQUIA-FASE 1

Colombia es considerado uno de los países con mayor biodiversidad a nivel mundial, y por tal motivo tiene un gran potencial para exportar diferentes productos agrícolas, entre los cuales está el café. Como objetivo del presente artículo se tiene caracterizar la calidad física del grano de café de los municipios cafeteros del norte de Antioquia, fase 1, para entrar en el mercado del café tostado y ser competitivos en la producción de café. Por esta razón, se utilizó una metodología tipo descriptiva y cualitativa en la que se tostó los granos de café almendra, se determinó el color de los granos tostados para establecer los grados de tostión, se les determinó el porcentaje de merma y, por último, se hizo un análisis organoléptico al café tostado. En la actualidad, el departamento de Antioquia cuenta con 79.452 caficultores y 122.206 hectáreas de café, según la Federación Nacional de Cafeteros; los municipios más representativos de la subregión norte de Antioquia con respecto al café son Angostura, Ituango, Santa Rosa de Osos (especialmente los corregimientos de San Pablo y San Isidro), Don Matías (especialmente la vereda Bellavista), Campamento, Gómez Plata, Guadalupe, Briceño y Yarumal. Como conclusión, se tiene que en la prueba de granulometría de las muestras de café almendra se identificó que el 60 % del grano de café se encontraba por encima de la malla 15, y los mejores resultados de las curvas de tostión del café almendra sana del municipio de Santa Rosa de Osos se obtuvieron con un tiempo de 480 a 660 segundos, y a una temperatura de 185 a 198 °C

First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

The search of extragalactic regions with conspicuous presence of Wolf-Rayet (WR) stars outside the Local Group is challenging task due to the difficulties in detecting their faint spectral features. In this exploratory work, we develop a methodology to perform an automated search of WR signatures through a pixel-by-pixel analysis of integral field spectroscopy (IFS) data belonging to the Calar Alto Legacy Integral Field Area survey, CALIFA. This technique allowed us to build the first catalogue of Wolf-Rayet rich regions with spatially-resolved information, allowing to study the properties of these complexes in a 2D context. The detection technique is based on the identification of the blue WR bump (around He II 4686 {\AA}, mainly associated to nitrogen-rich WR stars, WN) and the red WR bump (around C IV 5808 {\AA} and associated to carbon-rich WR stars, WC) using a pixel-by-pixel analysis. We identified 44 WR-rich regions with blue bumps distributed in 25 galaxies of a total of 558. The red WR bump was identified only in 5 of those regions. We found that the majority of the galaxies hosting WR populations in our sample are involved in some kind of interaction process. Half of the host galaxies share some properties with gamma-ray burst (GRB) hosts where WR stars, as potential candidates to being the progenitors of GRBs, are found. We also compared the WR properties derived from the CALIFA data with stellar population synthesis models, and confirm that simple star models are generally not able to reproduce the observations. We conclude that other effects, such as the binary star channel (which could extend the WR phase up to 10 Myr), fast rotation or other physical processes that causes the loss of observed Lyman continuum photons, are very likely affecting the derived WR properties, and hence should be considered when modelling the evolution of massive stars.Comment: 33 pages, accepted for publication in A&

Dynamic equivalence between atomic and colloidal liquids

We show that the kinetic-theoretical self-diffusion coefficient of an atomic fluid plays the same role as the short-time self-diffusion coefficient D_S in a colloidal liquid, in the sense that the dynamic properties of the former, at times much longer than the mean free time, and properly scaled with D_S, will indistinguishable from those of a colloidal liquid with the same interaction potential. One important consequence of such dynamic equivalence is that the ratio D_L/ D_S of the long-time to the short-time self-diffusion coefficients must then be the same for both, an atomic and a colloidal system characterized by the same inter-particle interactions. This naturally extends to atomic fluids a well-known dynamic criterion for freezing of colloidal liquids[Phys. Rev. Lett. 70, 1557 (1993)]. We corroborate these predictions by comparing molecular and Brownian dynamics simulations on (soft- and hard-sphere) model systems, representative of what we may refer to as the "hard-sphere" dynamic universality class