Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

To gain more information about the effect of surfactant on salicylic acid derivatives, the stoichiometric protonation constants of 5-Sulphosalicylic acid and 5-Hydroxysalicylic acid in 0.0%-2.5% (w/v) cetyltrimethylammonium bromide (CTAB) - water mixtures were determined at an ionic strength of 0.16 mol dm-3 and at 303 K. A potentiometric method was used and the calculation of constants was carried out using the computer program MINIQUAD75. These protonation constants values have been found to shift in micellar media as compared to those in pure water. The differences in the values have been attributed to the solvent properties of the interfacial and bulk phases involving contribution from the micellar surface potential in the case of charged micelles. The trend of log values of step-wise protonation constants with mole fraction of the medium have been explained based on specific solute-solvent interactions. In this study Distributions of species, percentage of species composition, protonation equilibria and effect of influential parameters on the protonation were also discussed.

A glassy carbon electrode was modified by drop-coating technique using 1,4,10,13-Tetraoxa-7,16-diazaciclooctadecano (diaza-18 -crown-6 or DA18C6) and Nafion (NF) for the determination of Pb (II) by square wave anodic stripping voltammetric (SWASV). The new electrode exhibits an increase in due to major pre-concentration of aza crown ether and ionic exchange of NF with metal cations. Optimal conditions were: 3 mmol L-1 DA18C6, 3 wt % NF, 10 mmol L-1 HCl as supporting electrolyte, a frequency of 15 Hz , an accumulation time of 300 s and an accumulation potential of -0.80 V. The detection limit was 0.09 μg L-1 and linear range was 10-50 μg L-1. Interference from metal ions such us Fe (II), Pb (II), Cd (II) and Cu (II) was also studied. The method is sensitive, selective and simple with a relative standard deviation of 11%.

The iron-manganese mixed monolithic catalysts were obtained by impregnation from nitrates as precursors. A monolithic support was studied with and without alumina as surface generator. The characterization consisted in XRD, SEM, Adherence test, SBET and TPR. The monolith was evaluated in the combustion of ethyl acetate. The preparation method was very satisfactory in terms of reproducibility and adherence of the deposited phase. The higher activity of IFeMnx with respect to Al3FeMnx may be attributed for the formation of the solid solution where the Fe is introduced to the bixbyite structure. However, the presence of defective MnOx species in monoliths without alumina which might help to improve their performance is observed.

Water resistance, mechanical properties, and limiting oxygen index (LOI) of wood plastic composites (WPCs) and neat polypropylene filled with different amounts (3, 6, and 9% by weight) of dolomite powder and wood flour (15 and 30 by weight) were investigated. Wood flour, dolomite powder, polypropylene, and wax were dry-mixed in a high-intensity mixer to produce a homogeneous blend. This blend was then compounded in a laboratory-scale single screw extruder. Test specimens were produced by injection moulding process from the pellets dried to moisture content of 1%. The thickness swelling and water absorption of the dolomite polypropylene composites (DPCs) and WPCs slightly increased with increasing dolomite powder content but the differences were not significant. The flexural modulus and tensile modulus of the WPCs and DPCs increased with increasing dolomite powder content while the flexural strength and tensile strength slightly decreased. The LOI of the WPCs and DPCs increased with increasing dolomite powder content, which extended the times to ignition of WPC and polypropylene. Based on the findings obtained from the present study, it can be said that 6 wt% dolomite powder is the optimum amount in the manufacture of WPC and DPC.

Increase in NOx emission is one of the important drawbacks for using biodiesel as an alternative for petroleum diesel. Several studies had been carried out to reduce the NOx emissions level in biodiesel. The present work is the result of an attempt wherein ferrofluid is added to rice bran oil methyl ester in the way of analyzing its effects on emission characteristics. Magnetite concentrate is exothermic and is known for its characteristics of releasing copious heat at higher temperatures. Nanofluid using magnetite was synthesized by reacting Iron II (FeCl2) and Iron III (FeCl3) in an aqueous ammonia solution to form Magnetite Fe3O4 (Ferro fluid). Release of heat by magnetite during the combustion process would counterbalance the conventional limitations related with biodiesel such as increased delay period, inferior combustion rate and higher NOx emissions etc. Experiments were conducted with Rice Bran Oil Methyl Ester (RBOME) and Rice Bran Oil Methyl Ester with addition of ferrofluid (RBOMEF) and are compared with petroleum diesel. RBOMEF was prepared comprising 97.7% biodiesel, 2% magnetite based ferrofluid and 0.3 % surfactant by volume was used in a Compression Ignition engine. The experimental analysis found a decrease in HC, CO and NOx emissions of 10.8%, 9.1% and 8.49% respectively.

High-quality anatase phased titanium dioxide thin films were prepared in this work using an easy, simple and cost-effective method. Normal, partially and highly oxygen-enriched atmospheres were provided during the spray pyrolysis deposition of titania in order to study the oxygen effect on the structure and morphology of the films prepared. High crystalline anatase nano-coatings stable at high temperature (700°C) could be obtained through the delaying of anatase-to-rutile transformation due to the filling of oxygen vacancies by the oxygen added to the spraying atmosphere. These nano-coatings constitute promising materials for different applications such as hydroxyapatite coated metal implanting, rechargeable lithium ion batteries fabrication, gas sensing and photocatalytic applications.

The aim of this study was to evaluate the fit of a cognitive behavioural model of headache in the population of University students, from Córdoba,Argentina. The direct and indirect contributions to pain intensity of control beliefs, beliefs and thoughts about pain and coping strategies weredetermined, as were the direct contributions of pain behaviours and disability. The sample was comprised of 382 students of both genders fromseveral Universities. Multiple instruments were administered to measure the variables proposed in the cognitive behavioural model of headachefollowed by a descriptive and exploratory analysis of the data. Structural equation modelling was used and revealed an acceptable fit of the modelbut with lower levels than the criteria proposed. The model was therefore redefined by eliminating two indicators and was then found to achieve abetter fit (CFI = .91; GFI = .95) and an optimal RMSEA index of .05. The new model explained 47% of the variance of headache intensity. All thevariables of the model predicted pain intensity directly, with beliefs and thoughts about pain having the greatest predictive value (β = 0.68).© 2018 Universidad Nacional Autónoma de México, Asociación Mexicana de Comportamiento y Salud. This is an open access article under theCC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

AbstractThe aim of this study is to assess the relationship between Sense of Coherence (SOC), health behaviors and self-perceived physical and mentalhealth in men and women. 448 undergraduate students participated in this study. The mean age was 21.3 years old (SD = 1.95). SOC, leisure timeand sleep predicted better mental health in men. Comprehensibility, leisure time, sleep and physical activity predicted physical health in men.Only manageability and meaningfulness predicted mental health in women. In this group, Manageability, leisure time, physical activity and dietpredicted physical health. These results can be used to help design strategies to encourage the adoption of healthy behaviors and healthier copingstrategies in late adolescents and emerging adults.© 2018 Universidad Nacional Autónoma de México, Asociación Mexicana de Comportamiento y Salud. This is an open access article under theCC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The study assesses the nutritional status of the families that are part of the research in the three communities from the analysis of consumption patterns that they have nutritional value and are also values local plants (native) can contribute these eating patterns. Interviews, tours of farms and case studies with small producers of the three communities: qualitative research on this type of data collection instruments including applied. The results showed that in nine consumption patterns of families studied have sufficiency in terms of access to nutritious foods exceeding 110%. The diversity index of the diet in terms of sufficiency in the week reached a range between 0.89 in Tisma Grande which is deficient in Santa Cruz is 0.92 which is acceptable and La Montañita No 2 is adequate food sufficiency with 1.08. In terms of dietary diversity that refers to different types of foods that are consumed by households in the week the results were average ranges between 9.3 to 9.7 meaning the existence of a variety of acceptable diet. For the second case study which was to know about the types of native plants and consumption patterns in order to rescue and use in their daily consumption habits and determined the following plants: Spinach (Spinacia oleracea), Milkweed (Amaranthus hybridus), Espadillo (Yucca elephantipes), purslane (Portulaca oleracea), Mora (Morus nigra), Cojombro (Sicana odoriferous), sweet potato (Ipomoea batatas), Piñuela (cheap Bromeliad), Panama (Sterculia apetala), Tempisque (Sideroxylon capiri) Caimito (Chrysophyllum cainito) among others. Definitely we define families consume food more calories you consume protein foods such as dairy, meats and sweets in your diet, but it is important to note that this does not indicate that there is a bad nutritional quality in families because protein intake is not defiente, but if you need to include the aforementioned food and food supplement consumption that generate proteins the body of families and a stable nutritional balance in order that the families introduced a state of optimal health and to meet their daily nutritional needs in relation to work performed every day in their small production plots.

This research aims to determine the concentration of pH in the leaflets of 17 clonal cultivars Spondias purpurea L., located in the Arboretum Alain Meyrat of the National Agrarian University. The methodology used was developed at various times, such as the collection of plant material, selection of 20 sheets of each clonal cultivar in good condition (healthy, green and full), weighing using a balance of the green mass of leaflets separating them rachis which were labeled with the name of each clonal cultivar. Regarding the determination of the concentration of H + ions (pH) proceeded to cut the leaflets and the rachis, standard fashion using 3g of each sample were macerated with same as a porcelain mortar until ground matter. Then determined qualitatively solubility of the leaflets, using solvents such as water (H₂0), benzene (C₆H₆), ethanol (CH₃-CH₂- 0H) and carbon tetrachloride (CCl₄), using 3ml of each solvent. A pH meter was used to determine the concentration of H + ions (pH) of the samples before and after the use of solvents. It was observed that the growing San Franciscano has a higher concentration of H + ions, thus increasing acidity, maintaining this behavior in all solvents used, like dry rachis; This result led to the conclusion that the presence of organic acids is high and therefore the species is phytochemically recommended for the preparation of infusions. Regarding dry leaflets, Cook cultivar had the highest acidity.