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Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The military defense was one of the main variables that explains the creation of public companies and the intervention of the State in Argentina in the 20th century. The Armed Forces managed an important part of Argentine industry and had a notable influence on the orientation of economic policy. However; within this concern for the basic industry not all forces acted in the same way. In addition to giving an account of the general role of the military industries, we will conduct a comparative study of basic petrochemicals (where the Army took direct involvement) and aluminum (developed by private capital driven by Air Force). In sum, we are interested to appreciate both the mechanisms used and the achievements made with these two "tactics" derived from the same "strategy", born of the military need to ensure the local provision of "strategic materials", whose results effectively modified the industrial structure of Argentina. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Sociedad Química del Perú is the property of Sociedad Quimica del Peru and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of ZARCH: Journal of Interdisciplinary Studies in Architecture & Urbanism is the property of Universidad de Zaragoza and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction--Aluminum is incorporated into water naturally and/or anthropically, health risk levels above 0,2 mg/l according to Colombian regulations. It can arise as an emerging contaminant when aluminum salt coagulants are used improperly in the clarification of drinking water. Objective--To evaluate air pollution for human consumption in the central region of Colombia, determine its potential origin and compliance with current regulations. Methodology--Exploratory research, analysis of the presence of aluminum in raw water and treated during the period 2008-2018, by means of samples and laboratory tests, as well as the hydraulic evaluation and the operation of water treatment plants, in municipalities of Los departments of Tolima and Cundinamarca, central region of Colombia. Results--In more than 30% of the municipalities evaluated, the presence of aluminum in the water for human consumption was evidenced, above the maximum allowed by the current regulations. In several cases it was due to deficiencies in the treatment process where aluminum salts are used for coagulation, without adequate dosage as occurred in the municipality of Melgar, or due to high concentrations present in the water supply sources, such as the case of Magdalena river in the central region of Colombia. Conclusions--Aluminum in water for human consumption is due to its presence in water sources and the product of hydraulic and operational deficiencies in the clarification process of treatment plants where aluminum sulfate is used as a coagulant, due to inadequate application of optimal doses, poor intensity of agitation and speed gradients in fast mixing and flocculation, flocculation and sedimentation times outside the optimal range. [ABSTRACT FROM AUTHOR]

Acidic soils are approximately 35% of arable soils and one of the most important limitations in agriculture. The restriction in the growth and production of the culture with a pH lower than 5.0 is mainly due to the formation and migration of aluminum ions (Al3 +). With this background, the growth toxicity of two varieties of Phaseolus vulgaris L. var. "canario" and var. "panamito" was analyzed. The completely randomized experimental block design had the treatments of 50 µM, 25 µM and 0 µM, with three repetitions each. The seedlings were adapted in a hydroponic system, which contained the modified Hoagland nutrient medium and the different concentrations of aluminum. After three days root length, fresh and dry weight, accumulation of the metal in leaves and roots, peroxidase activity, protein percentage were evaluated. The panamito was more sensitive in relation to the canario according to the evaluated variables. Aluminum accumulation was greater in the leaves for the panamito and in the roots for the other variety. It is concluded that the canario is more tolerant than the panamito variety. [ABSTRACT FROM AUTHOR]

The objective was describing the use of kaolin as an extern marker in the dry matter supplement intake and fecal output of cattle grazing. Many markers have limitations, kaolin is a possible intake marker with applicability, because it has acceptable physical and chemical characteristics. The quantification is performed indirectly by aluminum present in the substance, and determined by colorimetric method with aluminon. Currently, research in animal nutrition has presented interesting information, however, flaws in the analytical methodology of kaolin have shown unsatisfactory results. An effective alternative is nitro perchloric acid digestion associated with hydrofluoric acid. So, research for new practical and low-cost methodologies that present accurate and robust results is still necessary. [ABSTRACT FROM AUTHOR]

Introduction: aluminum is incorporated into water naturally and/or anthropically, health risk levels above 0,2 mg/l according to Colombian regulations. It can arise as an emerging contaminant when aluminum salt coagulants are used improperly in the clarification of drinking water. Objective: to evaluate air pollution for human consumption in the central region of Colombia, determine its potential origin and compliance with current regulations. Methodology: exploratory research, analysis of the presence of aluminum in raw water and treated during the period 2008-2018, by means of samples and laboratory tests, as well as the hydraulic evaluation and the operation of water treatment plants, in municipalities of Los departments of Tolima and Cundinamarca, central region of Colombia. Results: in more than 30% of the municipalities evaluated, the presence of aluminum in the water for human consumption was evidenced, above the maximum allowed by the current regulations. In several cases it was due to deficiencies in the treatment process where aluminum salts are used for coagulation, without adequate dosage as occurred in the municipality of Melgar, or due to high concentrations present in the water supply sources, such as the case of Magdalena river in the central region of Colombia. Conclusions: aluminum in water for human consumption is due to its presence in water sources and the product of hydraulic and operational deficiencies in the clarification process of treatment plants where aluminum sulfate is used as a coagulant, due to inadequate application of optimal doses, poor intensity of agitation and speed gradients in fast mixing and flocculation, flocculation and sedimentation times outside the optimal range. [ABSTRACT FROM AUTHOR]

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: The biogeographic Chocó presents an exuberant diversity of arboreal species; however, it is unknown if soils determine this diversity. Objective: Evaluate how edaphic conditions explain the diversity and arboreal dominance in tropical pluvial forests at a local scale. Methods: Seven permanent research plots were established in the forests of Opogodó, Pacurita and Salero. In these plots, tree diversity and dominance were measured, and edaphic conditions such as organic matter (OM), acidity, nutrients and texture were determined. Results: It was found that the diversity was much greater in Salero and Pacurita; but the dominance was greater in Opogodó. The diversity was positively related to phosphorus, aluminum, silt and clay; while, with pH, OM, calcium, magnesium, potassium and sand, the relationship was negative. On the other hand, dominance was negatively related to P and Al; while, the relationship was positive with pH, OM, Ca and sand. Conclusions: It was corroborated that the arboreal diversity is negatively related to some variables (Ca, Mg, K) of edaphic fertility. Apparently, edaphic infertility, acidity and aluminum toxicity, determine tree dynamics and diversity. [ABSTRACT FROM AUTHOR]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

La demencia postdialítica es una comorbilidad relativamente frecuente en pacientes con enfermedad renal crónica y se desarrolla después de varios años de tratamiento. Las características clínicas más frecuentes incluyen alteraciones cognitivas, mioclonías y crisis epilépticas. Actualmente su diagnóstico es menos frecuente desde que se eliminó el aluminio de los líquidos para diálisis; sin embargo, se han descrito casos esporádicos donde persiste la correlación entre la terapia dialítica, la intoxicación con aluminio y las alteraciones neuropsiquiátricas, con fuentes de intoxicación como aguas poco tratadas. Presentamos el caso: paciente femenino de 57 años, cuyo familiar refirió enfermedad actual desde 1 mes previo a su ingreso al hospital, después de recibir terapia hemodialítica, inicia de forma progresiva e insidiosa, desorientación en tiempo y espacio, a la que se asoció cambios bruscos del humor con episodios de ira inmotivados, asociándose progresivamente alteración de la memoria, y se agregan movimientos involuntarios, continuos, reptantes, amplios, en 4 extremidades, por lo que es evaluada por servicio de neurología. Al examen de las funciones mentales superiores, se encontró desorientada en tiempo y espacio, bradipsíquica, hipertímica displacentera con tendencia a la depresión, lenguaje hablado fluente, articulado, incoherente, comprendía órdenes sencillas de forma ambígua, no denominaba, no repetía. Presentó movimientos de flexo-extensión, repetitivos, en miembros superiores e inferiores, bilaterales, amplios, sinuosos hacia la línea media, sugestivos de movimientos coreatetósicos. Entre los resultados de pruebas de laboratorio resaltan niveles de aluminio sérico en 136±7ugr/l, con valores normales de 1-5ug/l. La demencia postdialítica es inusual en la actualidad, gracias a la mejora en los líquidos de diálisis, que contienen cantidades mínimas de sales de aluminio. Sin embargo; se conoce que la sangre de los pacientes en hemodiálisis se expone de 60 a 90 litros de agua en cada tratamiento. En caso de enfermedad renal, la fijación del aluminio a las proteínas plasmáticas es elevada, por lo que la captación de aluminio será importante incluso en los casos en los que la concentración del metal en el líquido de diálisis sea pequeña. Aunque la incidencia de demencia postdialítica ha disminuido, se ha demostrado que los pacientes con enfermedad renal crónica, presentan predisposición a acumular aluminio en los tejidos corporales, por disminución en su excreción renal, siendo frecuente su acumulación en la corteza cerebral. El tratamiento se basa en la administración de quelantes como la desferrioxamina. [ABSTRACT FROM AUTHOR]

Copyright of Revista Avances: Investigación en Ingeniería is the property of Universidad Libre, Facultad de Ingenieria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Archivos Latinoamericanos de Nutrición is the property of Sociedad Latinoamericana de Nutricion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The deformation of polycrystalline aluminum (95.5%) was studied in the absence and presence of flow. highenergy electrons (Е = 0.7 MeV, φ = (0.7... 5) ·1048 cm-2-s-1). In continuous mode determined to reduce the level of deforming stress, the hardening coefficient as a function relative elongation, sample thickness and flux density. An increase in plasticity has been established metal as a result of electron beam exposure. Temperature measurement during deformation allowed us to identify the contribution of radiation-induced effects on the change in mechanical characteristics of aluminum. The possible mechanisms of the phenomenon are discussed. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation was studied using oxalic acid (1.6 M), varying some conditions, as: current density (Ia = 1-3 A/dm²), electrolytic bath temperature (Ta = 40-50 °C), anodizing time (ta = 40-100 min) and a post-anodizing treatment (PA) at different current densities (Ia = 1-3 A/dm²) with a constant post-anodizing time (tPA = 40 min) and increasing the treatment time (tPA = 0-120 min) at constant current density (Ia = 2 A/dm²). The variation of these conditions showed that the Al2O3 formation depends on two fundamental processes. First, it is the generation of an anodic oxide layer followed by its dissolution on internal and external surface of the pore. The influence of each variable on these two stages causes the generation of layers with texture and roughness specific characteristics. Similarly, it was demonstrated that independently of the geometric shape, a morphological equivalence of the anodic Al2O3 in the aluminum substrates was obtained. Furthermore, a trend in the pressure drops: MACL1100 > MAE40 > MAE20 > MAE10 > MACL350 was observed; this performance depends of the spatial distribution and cells number. [ABSTRACT FROM AUTHOR]

In the present work, the effect of the addition of the corrosion inhibitor cerium nitrate (Ce(NO3)3.6H2O) and the aging time were evaluated during the synthesis of hybrid sol-gel coatings applied on the AA2050-T8 aluminium alloy. Sols were prepared from a mixture of the precursors tetraethylorthosilicate (TEOS) and glycidoxypropyltriethoxysilane (GPTMS) in a molar ratio TEOS:GPTMS of 3:1, using acetic acid and ethanol as catalyst and solvent respectively. The hydrolysis and condensation process of the hybrid sols was monitored by Fourier Transform Infrared (FTIR) Spectroscopy and rheological tests, whereas sol-gel coatings were characterized using attenuated total reflectance infrared spectroscopy (FTIR-ATR), scanning electron microscopy (SEM), contact angle measurements, and scratch tests. The experimental results showed that the physicochemical characteristics of the hybrid sol-gel coatings obtained were influenced by both the aging time and the addition of the corrosion inhibitor. In this regard, an increase of the aging time resulted in uniform coatings with an adequate adhesion and greater hydrophobic features. On the other hand, the effect of the addition of cerium nitrate in the gelation process was more significant, producing coatings with superior physicochemical features, even for short aging times. [ABSTRACT FROM AUTHOR]

The inhibition efficiency of corrosion of the extract of neem leaves (Azadirachta indica) on carbon steel and aluminum was evaluated in contact with a sodium chloride and sodium sulfate solution, both at 3.5% p/v. Corrosion speed was determined and it was found that the Neem extract, at a lower concentration, reached better efficiencies on carbon steel in sodium chloride with 78% efficiency using 5% of the extract; concerning the aluminum, the efficiency values reached were low. Besides, through the adjustment to the Langmuir's isotherms, it was possible to determine that the nem extract was adsorbed spontaneously on the surface of carbon steel and allowed to delay the corrosive process when reaching inhibition efficiencies of 90%. Results of this research allow establishing that the neem extract has a high potential as corrosion inhibitor to be applied in the industry as corrosion preventive medium. [ABSTRACT FROM AUTHOR]

Copyright of Revista ION is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A site evaluation was conducted on a landfill of dredged sediment from the Reconquista River on top of a geomembrane with spontaneous willow tree vegetation. Sediment samples were taken up to a depth of 1 m, and were analyzed for potential contaminant presence as well as soil variables. The results showed an incipient pedogenesis and presence of Cd, Ni and Zn metals in the soil solution 7 years after disposal. Organic carbon accumulation, sediments particle size, and color change were detected. Bulk density was found to be less than 1 g cm-3 and porosity was large, mainly due to cracks. pH was very low, (3.8 in situ, 4.5 in the laboratory), enhancing these elements' solubility. On surface, total amount of Cd was 1.2 mg kg-1; Cr 16.6 mg kg-1; Cu 43.9 mg kg-1; Ni 14 mg kg-1; Pb 32.9 mg kg-1 y Zn 131,7 mg kg-1. Volatile organic compounds (PHAs) were identified by mass spectrometry confirming the original sediment contamination. The C distribution in the soil profile suggests a natural attenuation process. The TCLP test (leached quality) was used to evaluate possible metal stabilization techniques. Five treatments were applied: control, two rates of lime-sediment, 1:20 and 1:50; cement with the same two rates and calcium superphosphate fertilizer 1:40. Metals and metalloids found in the soil solution were Al, Cd, Ni and Zn. The TCLP test was applied to the control and to all treatments, stabilized and prevented 100% leaching of Al, Cd and Ni but not for Zn. The fertilizer treatment decreased equilibrium pH throughout the profile increasing Al solubility in the entire soil profile, of Cd and Ni at intermediate depth, while Zn solubility was not modified. Stabilization techniques with calcium amendments would be the best alternative to reduce the biomagnification risk through the entrance of metals in the food chain and could create better conditions for the attenuation of hydrocarbons which could be hazardous for the population's health. [ABSTRACT FROM AUTHOR]

The objective of this investigation is to increase the resistance to abrasion of the NI-Resist cast iron alloy through particle precipitation while maintaining chemical stability unchanged by adding aluminum as intermetallic compound inducer. This contributes to the formation or precipitation of homogenous particles. Ni-Resist alloy samples types 2 and 3 were used maintaining nickel percent unchanged while varying the aluminum content. Aging thermal treatment was applied to induce the particles. The results indicated that the addition of aluminum as an alloying element to the Ni-Resist alloy increases the resistance to wear through particle precipitation due to its capacity as an intermetallic compound inducer. 0.5% aluminum addition produced the best results. [ABSTRACT FROM AUTHOR]

Important events of acute mortality without apparent pathological features are present in the salmon smolt production in the Araucanía Region (southern Chile). The problem is focused on specimens of 0.2 to 1 g; causes points to pH acidification processes of running water and the presence of certain heavy metals, among which aluminum, reaches concentrations beyond ranges tolerated by fish. Scientific information indicates that concentrations of 5 mg Ca L-1 in the affluent are enough to keep the fish safe from toxic effects of aluminum. However, problems in the production of smolt indicate that greater scientific knowledge and experimental evidence is required that supports the development of processes and technologies for effluent treatment in Chilean fish farms. In this work the effect of four calcium concentrations (0, 5, 10 and 20 mg Ca L-1) on the acute toxicity of 500 mg Al L-1 in juvenile rainbow trout (Oncorhynchus mykiss) of 0.1 g was evaluated in culture water at pH 5, 6 and 7. The objective was to determine the dose of calcium that reduces the acute toxicity of aluminum and the reaction times that fish farmers could have to take preventive measures for acute aluminum concentration in the culture water. The results indicate that within 8 h of exposure to a toxic concentration of aluminum farmers should ensure a dose exceeding 10 mg Ca L-1 in the culture water and pH >6 as remedial measure to reduce the effect of acute intoxication for aluminum. [ABSTRACT FROM AUTHOR]

Copyright of Avances en Ciencias e Ingeniería is the property of Avances en Ciencias e Ingenieria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aluminum coatings were deposited on stainless steels AISI 304 and AISI 316 at a temperature range from 560 to 600°C by CVD-FBR, using a bed consisting of a 10% aluminum powder and 90% of bed inert (alumina) which was fluidized with Ar and an activator mixture of hydrochloric acid with hydrogen (HCl/H2). The coating without heat treatment includes the follow species: Al13Fe4, Fe2Al5, FeAl2 and Al5FeNi for both steels. In addition, the heat treatment causes the aluminum to diffuse into the substrate and the iron diffuse towards the surface of the coating, making the transformation of previous existing compounds to FeAl, Fe2Al5, FeAl2, Al0.99 Fe 0.99 Ni 0.02, AlNi and Fe2AlCr. Thermodynamic simulation was conducted with the Thermo-Calc software to obtain information of the possible composition and amount of deposited material, for selected conditions. The specimens coated and uncoated were exposed at 750 °C in an atmosphere where the vapor was transported to the samples using a N2 flow of 40 ml/min plus 100% water vapor (H2O). The two uncoated substrates behaved differently, since the steel AISI 304 performed well and gained little weight (0.49 mg/cm2), compared to the steel AISI 316 that lost too much weight (25.4 mg/cm2). Coated steels gained little weight during thousand hours of exposure (0.26 mg/cm2) and support very well the corrosive attack compared to uncoated substrates. [ABSTRACT FROM AUTHOR]

The aim of this work was to show the preliminary results related to the synthesis of hybrid sol-gel coatings for corrosion protection of the commercial AZ31 and AZ91D magnesium alloys, and the AA2124-T4 and AA2050-T8 aluminium alloys. For this purpose, hybrid sols were prepared from a mixture of the inorganic precursor tetraethylorthosilicate (TEOS) and the organics precursors glycidoxypropyltriethoxysilane (GPTMS) and 3-aminopropyltriethoxysilane (APTES). Two experimental variables were fixed: the molar ratio APTES:GPTMS (from 0,15:1 to 0,25:1) and the aging time (from 10 to 60 minutes). Later, sol-gel coatings were obtained by deposition of these sols following the dip-coating route. Coatings were characterized using Scanning Electron Microscopy (SEM) while Fourier Transform Infrared (FTIR) Spectroscopy and rheological tests were used to analyze the sol properties. On the other hand, corrosion resistance was evaluated by potentiodynamic anodic polarization test in aerated 0.1 M NaCl solution. The experimental results showed that, under some specific experimental conditions, it was possible to obtain homogeneous and uniform coatings with excellent corrosion resistance with regard to the parent alloy. The precursor APTES was confirmed as a key variable during the gelation process. Its properties substantially modified the sol viscosity, affecting the morphological features and the corrosion protection of the coatings. [ABSTRACT FROM AUTHOR]

Oxidation was made of austenitic stainless steel AISI 317 aluminum coated by chemical vapor deposition in a fluidized bed at temperatures of 700 °C and 750 °C, in an environment with 100% steam, to evaluate their corrosion performance. Gain mass curves were ground and oxide films were analyzed by SEM and X-ray diffraction to observe the morphology of the oxides. Thermodynamic simulation was carried out during steam oxidation of the substrates for possible solid and gaseous phases which could be formed in the presence of an environment with 100% water vapor and atmosphere pressure. The form of attack at 750 °C is similar to 700 °C, although the rate of oxidation is increased, because the diffusion of the alloying elements and the oxidation reactions are faster. Aluminum coatings have good resistance to steam oxidation and forming a surface layer of Al2O3, that is dense and adherent, which protects the substrate from corrosion attack. [ABSTRACT FROM AUTHOR]

Introduction: Aluminum (Al) is a toxic element which may contaminate pharmaceutical products used as individual components to prepare total parenteral nutrition mixtures (TPN). Objectives: 1) to determine Al levels in the individual components used to prepare TPN mixtures; 2) to compare detected Al levels with those imposed by international regulations (FDA); 3) to calculate the total amount of Al administered to adult and children receiving those typical TPN mixtures. Methods: Al was determined by Inductively Coupled Plasma- Atomic Emission Spectrometry (ICP-OES) (Perkin Elmer OPTIMA 5100 DV) in 44 individual products, from different labs and lots, belonging to 16 components available in Argentina: dextrose and amino acids for adult formulas and for pediatric formulas: lípids; potassium chloride; sodium chloride, magnesium sulfate; sodium phosphate; calcium gluconate; sodium glycerophosphate, zinc sulfate; multitrace elements; steril water (ampoules and great volume presentations). Results: Al levels were detected in 43 of the 44 the studied components, except sterile water. The components of large volume presented between 249 y 1,580 μg Al/ L, between 4 and 180 times FDA established levels (25 μg Al/ L). Small volume components presented Al levels between 85 y 4,909 g/ L, not declared in labels. Conclusions: The highest amounts of Al were detected in calcium gluconate, sodium phosphate and multitrace elements. 2) Usually prescribed TPN mixtures would have higher Al levels than those accepted by FDA regulation; 3) The highest aluminum concentration was provided by dextrose, amino acids and lipids in adult TPN mixtures. In neonate TPN mixtures, Al highest amounts were provided by dextrose and calcium gluconate. The calculated concentration of Al in TPN mixtures was higher than those stipulated by international regulation (5 μg Al/kg (body weight)/ d). It would be advisable for manufacturers to declare the content of aluminum in the label, with the aim of avoiding toxicities which would compromise the critical patients' evolution. [ABSTRACT FROM AUTHOR]

Copyright of Revista Investigaciones Aplicadas is the property of Universidad Pontificia Bolivariana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this research was to determine the effect of bio- film detachment, formed in a water distribution network, on the quality of water delivered to households, given that this may affect people's health and quality of life. Analyses of pH, turbidity, concentration of metals and microbiologi-cal in the water supply network were undertaken to find the effect of biofilms on water quality. We found high levels of aluminum and microorganisms with highly resistance spore structures that are difficult to control and represents a potentially health problem for the population [ABSTRACT FROM AUTHOR]

In this research we studied the dynamics of nucleation and growth of palladium on aluminum. The use of cyclic voltammetry technique, allowed to find the region where the reduction reaction of palladium occurs. Then cathodic currents were studied under potentiostatic conditions in terms of theoretical models of diffusional nucleation, based on transient processes such as those established by Sluyter [ J. Electroanal. Chem 177 (1984) 13] and HeermanTarallo[J. Electroanal. Chem 470 (1999) 70]. Were determined nucleation parameters: the coefficient of diffusion of ions palladium (DPD), the nucleation rate constant (A) and the number of active sites (N_O) on aluminum. Was characterized morphologically by electron microscopy instrumental techniques (SEM) and EDX, the nucleation process of palladium by pulsedelectrodeposition under slow growth, with pre oxidation. [ABSTRACT FROM AUTHOR]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We present data from hair samples collected from 316 subjects for chemical elements analysis (CEA), obtained between years 1991 to 2011 in different cities of Venezuela. The objective was to determine the presence of some deficiency or excess of essential elements and to assess the levels of some toxic elements. The CEA is a method that shows the concentration of elements in a period of months, according to hair growth, because blood or urine samples only shows a profile of hours or days of exposure to a substance. For acute toxicological effects urine tests are more suitable. The findings obtained with CEA show the concentration of some chemical elements in healthy subjects and patients over the years and geographical areas studied. We observed a year time decrease of the concentration of Iodine element (mean values of 2.55 ± 0.35 ppm to 1.21 in 2010 and 1.96 in 2011), lithium (mean values of 0.0126 ± 0.001 ppm to 0.0057 in 2011), Lead (mean values of 7.05 ± 0.56 ppm to 2.28 in 2010 and 1.62 in 2011). Uranium in hair samples revealed a higher proportion in subjects of the insular region (Porlamar, Margarita's Island). Also shown is the nonhomogeneous distribution of selenium in several areas of Venezuela, which was higher in the Andes region. Mercury was found higher in Tucupita City (Delta Amacuro). The items reported are nutrients elements as iodine, lithium and selenium; and toxic elements as lead, aluminum, uranium and arsenic. [ABSTRACT FROM AUTHOR]

Superplastic forming (SPF) has become in recent times as a potential technological process based on the superplastic behavior that demonstrate different alloys, finding applications in aerospace, aeronautic and automotive industries. This behavior allows reaching strains of 8000% due to the mechanism of grain boundary sliding (GBS). In fine structure superplasticity (FSS), the refinement of grain size favors the above deformation mechanism. The processing of materials by friction-stir (FSP) is a newly developing issue and produces a strong grain refinement. The thermal stability of the fine structure produced is a key aspect, whereby only few systematic studies on the influence of processing parametres on thermal stability of the microstructures obtained by FSP are available. The aim of this study was to evaluate the thermal stability of aluminum alloys processed by FSP. Samples of AA5052, AA5088 and AA7075 were processed by Friction Stir, under different rotation and feed speeds. Extracted samples were heat treated to different temperatures, between 310 and 550°C, analyzing the thermal stability of the microstructure. Critical time and temperatures were determined for the start of abnormal grain growth (AGG). A strong influence of processing parameters on microstructural evolution was detected. It was observed that stability increased with decreasing the rate of speeds. [ABSTRACT FROM AUTHOR]

Aluminum powders were mixed with sodium chloride having particle sizes between 150-212 µm and weight fractions of aluminun (fAl) between 0.30 and 0.55. The mixtures were compacted at a pressure (Pc) between 5 and 25 MPa and sintered at 640°C for 2, 6 or 8 h in a stream of N2. The resulting preforms were cooled down to room temperature and sodium chloride particles were dissolved in hot water. Visual inspection of the materials allowed us to demonstrate that the fAl and Pc are determining factors in the conservation of the final form of aluminum sponges. A relatively low Pc (5 MPa) does not allow sufficiently strong binding of the particles during the sintering process. On the other hand, samples prepared at higher fAl above 0,50 showed a uniform metallic look while maintaining the cylindrical shape without malformations or shedding their profiles. However, it was observed a breakdown of the preform during dissolution process when lower fAl were used. SEM micrographs of samples prepared showed, firstly, the formation of interconnected pores which indicates the formation of open-cell cellular materials. In addition, it was observed the formation of a thin layer of alumina at the surface; the quality of the alumina shape (whiskers) is improved when the sintering time is raised from 2 to 6 and 8 h. This surface could be used for the controlled growth of alumina and posterior anchorage of a catalyst. [ABSTRACT FROM AUTHOR]

Aluminium toxicity is a very important factor limiting growing and crop productivity in acid soils. The aim of this research was to study the aluminium effects on cell division and elongation process and their relationship with root growing on two rice commercial cultivars. Different AlCl3 levels were employed to impose stress condition. Root apical segments were processed by traditional procedure to optic microscopy. The stained sections were viewed with on optic microscopy (Zeiss) and photographed with a digital camera coupled to microscopy. Morphometric Program ImajeJ was employed to determine cell dimensions. Root elongation was reduced in rice seedlings as a consequence to aluminium toxic effect. A mitotic index inhibition and reducing length and radial expansion was observed on meristematic root cells with the increase of aluminium level. The obtained results evidence some changes caused by aluminium toxic levels in both cellular process which are responsible of cell growing inhibition. [ABSTRACT FROM AUTHOR]

In order to assess the effect of Si on the thermal stability of TiC in molten Al, TiC particles were incorporated into Al melts of high purity and Al-7wt.%Si. The composites were heat treated between 500°C and 1000°C and held at temperature for 48 and 6 h for the pure Al matrix and the Al-7wt.%Si alloy, respectively. The samples were characterised by scanning electron microscopy, X-ray diffraction and image analysis. The findings revealed that TiC slowly reacts in solid state, but the reactivity increases in liquid state with temperature to a maximum at 725°C and 800°C for pure Al and the Al-7wt.%Si alloy, respectively. The degradation of TiC particles in the Al melts resulted in the precipitation and growth of intermetallics into blocky shapes and little blocks of Al4C3. The latter phase was seen to coat the remaining TiC particles in heavily reacted samples. At temperatures larger than 725°C, the reaction between TiC and Al to form TiAl3 and Al4C3 decreased and between 800°C and 1000°C, dissolution of TiC in Al produces Al4C3 in decreasing levels as the temperature increases. In the Al-7wt.%Si alloy, this tendency was observed at temperatures larger than 800°C. Energy dispersive X-ray analysis of the intermetallics formed in the Al-7wt.%Si alloy and X-ray patterns of the heat treated samples indicated an average composition of TiAl2.39Si0.39 with the crystalline structure of the TiAl3 phase. Comparison of the remaining TiC fractions in the Al melts reveal that Si enhances the kinetics of the dissolution of TiC and that the mechanism is different at "low" and "high" temperatures. [ABSTRACT FROM AUTHOR]

In this research, the thickness of the oxide layer and the microhardness of anodized aluminum Al3003 and Al6063 are modeled based on process parameters. To this end, studies of the microhardness and the thickness layer of the anodized surface were made, via techniques of multifactorial analysis and robust design. The following levels of the process parameters were established: temperature [15 °C, 25 °C], time [30min; 60min], electrolyte concentration [1,2M; 2M], current density [1Amp/dm2; 3Amp/dm2], aluminum [Al3003, Al6063], and as a noise parameter, the plastic deformation [0%, 10%, 20%, 30%]. A combined fractional design 27-2 was proposed, based on which a total of 48 tests were performed using sulfuric acid electrolytic solutions. The measurement of microhardness was performed using a Vickers indenter loaded at 400g, and the thickness of the oxide layer was captured using electron microscopy. Variance analysis (ANOVA) was applied to the results in order to determine the significant factors and the robustness of the effects. Results of microhardness [HV] [85,74-308,87]; and the oxide layer thickness [µm] [12,82-94,69] were determined. Finally, the equations for the prediction models are shown for each response as a function of the significant factors, these equations will allow the selection of the microhardness and thickness of oxide layer to fulfill the requirements of a particular product using an appropriate selection of process parameters. [ABSTRACT FROM AUTHOR]