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

The large amount of organic waste obtained from agro-industrial production processes are very important materials for organic agriculture, as they can improve the physical, chemical and biological quality of soils. For this reason, a trial was carried out at the “La Troncal” mill, Guayas-Ecuador (2009-2010), to test three combinations of agro-industrial residues; establishing a multifactorial experimental design and examining three different combinations of filter cake, molasses and ash; two sources of microorganisms; and two types of aeration. Regression (Generalized Linear Models) was applied, through the stepwise method, of posterior elimination, to model the relationship between the dependent variable (carbon nitrogen C/N ratio) and the independent or predictive ones: Height, Organic Matter content, Conductivity, Percentage of Organic Matter and Ash in the formula, Micro-Organisms, Temperature, pH and Aeration. The final model was: E[C/N] = -10566.1 + 66.5738*Altura - 0.19824*Altura2 - 1.8069*Altura*MOCromat - 0.4597*Altura*Temp - 0.2226*Conduct + 0.0015*Conduct*F%Cenizas + 0.0039*Conduct*Temp - 18.411*F%MO + 0.3609*F%MO*Temp + 32.0059*MicroOrgC + 188.788*MOCromat + 299.196*Temp - 2.7438*Temp2 + 27.0893* pH - 90.2597*Aireac + ε.  Which turned out to be a good explanatory and predictive model to measure dependency and estimate the possible values ​​that the C/N ratio takes based on the initial values ​​of the independent variables. The temperature parameter is the most critical, since compost production is a dynamic process, similarly to pH and conductivity. The probability of obtaining the best compost according to the Monte Carlo method is greater when placing between 33% and 35% OM, 19% Ash and 100% of the pile is completed with Humidity; applying commercial microorganisms; using turning as aeration method; and having at the beginning of the process the conductivity in values ​​between 2750 and 2850 µS/cm; around 55ºC of temperature and 7.5 of pH.  

The cerambycid insect Xylotrechus arvicola is considered a pest that affects the wood of the grapevine (Vitis vinifera) in the major wine areas of the Iberian Peninsula. The larva of this insect perforates the grapevine wood, resulting in structural and biomechanical failure of the vine plants. Vine samples from wood damaged by Xylotrechus arvicola larvae were picked up from different vineyards and grape varieties. Compressive and flexural tests were performed in order to assess the mechanical behaviour of the wood samples. Total length of the cracks in wood samples (TLCWS) that appeared on the surface of the grapevine wood samples after the mechanical tests was measured. Compressive strength (CS) and flexural strength (FS) decreased with the increase of the cross-sectional area (CSA) of both branches and trunks, regardless of damage condition or water content. Moreover, the resistance was lower in damaged wood. In addition, this was verified through the linear regression coefficients of the interaction CS x CSA and FS x CSA. TLCWS in branches and trunks of damaged samples was greater that in undamaged samples. Also, TLCWS within the same damage condition and part of the plant was higher in dry samples than in fresh samples. The damaged wood would show a higher vulnerability to common mechanical stress suffered by the grapevines in the field including heavy winds, fruit overweight or harvesting machines shaking (when mechanically collected). Larvae of this insect altered the mechanical behaviour of the trunk and branches of grapevine wood. The mechanical strength of wood was more negatively affected when the CSA of the branches and trunks increased. Longer TLCWS was found in affected wood.of an emerging grape pest, Xylotrechus arvicola (Coleoptera: Cerambycidae)

Development of new materials puts a great emphasis on saving production costs, energy, decreasing the amount and number of chemicals used during the manufacturing process. Bio-based materials can be ecologically produced and recycled after their lifespan, which saves the environment. The recent interest in bio-based materials led to the objective of this work. In this article, the structure of spruce wood (Picea abies) biodegraded by the white-rot fungus Trametes versicolor and brown-rot fungus Gloeophyllum trabeum was studied. Structure of the wood was observed macroscopically and microscopically. Classic and unusual stain combinations were used in this work. Ethanol was intentionally omitted in the process of making permanent mounts. It was done to preserve the coherence of the decayed microsections and to keep small fragments from being rinsed away. Results of the observations suggest that spruce wood decayed by these fungi could be used as an insulation material. Wood decaying fungi decrease the density of wood and increase its porosity. A low density and high porosity are important properties for insulation materials. According to the results, spruce wood decayed by Trametes versicolor would be more suitable to be used as an insulating material.

Bamboo biomass was pulped using organosolv methods: Acetic acid and formic acid; hydrogen peroxide and formic acid; ethanol and water and kraft process with varying concentrations of the cooking chemicals. The properties of the isolated lignin were influenced by the black liquor pH as well as the pulping method. Highest pH (12,8) was recorded for kraft at 70:30 liquor concentration while lowest pH of 2,5 was recorded for both Aceticformic (70:30) and Ethanol/water (70:30 and 60:40). There were obvious differences in the characteristic colours, shapes and sizes of the lignin samples. Bamboo kraft lignin samples formed large pieces much easier than that of Organosolv. Aceticformic (70:30) had the best filteration properties (FC) while Ethanol/water had the poorest. Generally, kraft recorded the highest lignin yield while all the organosolv processes recorded reduced yield. Highest yield (119,25 g/L) was gotten from kraft (50:50) while Peroxyformic (60:40) had the lowest yield of 8,20 g/L. The results showed that higher liquor pH favours total dissolved solid as well as lignin precipitation. As the pH increases, total dissolved solid, yield, Klason and low molecular weight (LMW) lignin content increases while FC decreases. The Klason and LMW lignin content increased with incresing lignin yield.

Identifying wood species of each wood element of a historical wooden building and investigating the changes in wood properties due to exposed outdoors during its service life are important prerequisites for the maintenance and renovation of historical wooden buildings. In the present study, the changes in wood properties occurring during natural aging of two facade elements taken from a traditional house, which has a service life of approximately 100 years, were investigated. Destructive tests were used for the experiments. The wood species, moisture content, wood density, water absorption rate and chemical structure of both facade elements were determined. Microscopic analysis revealed that the molding was made from the wood of Scots pine (Pinus sylvestris) and the window jamb was made from chestnut (Castanea sativa). It was found that the cellulose and lignin on the outer surface of aged woods of both facade elements were degraded according to the FTIR analysis. The moisture and density values of aged wood for both facade elements were smaller than those of recent wood. The water absorption rates of aged woods of both molding and window jamb increased with natural aging.

In the space of transformations, the study of the existence of infinite σ-finite measures is rather scarce, are limited to a couple of examples, one of which is the Boole transformation, which preserves the Lebesgue measure and is ergodic with respect to this measure. In this paper we consider this type of transformations with two horizontal asymptotes, showing for a large family of four parameters that, under certain conditions, exhibits an infinite ergodic measure and that under other conditions to the parameter space that family exhibits an ergodic probability measure; in both cases the measure is equivalent to the Lebesgue measure.

In the space of increasing transformations without fixed point of the real line with a vertical asymptote, conditions have been shown to determine chaos, but the case with horizontal asymptotes has been little studied. In this work we study this kind of transformations on the real line with a vertical asymptote and two horizontal asymptotes, demonstrating conditions to obtain transitivity and that the set of periodic points is dense on the real line. In addition, it is shown that the existence of periodic orbits of period 2 or 3 eliminate the possibility of transitivity.

The aim of this document is to introduce basic concepts of statistical mechanics in equilibrium, and to highlight the relationship that exists between the microscopic and macroscopic worlds. It begins with concepts of thermodynamics. To then conclude with the statistical ensemble. The development of the theory is based on the presentation of illustrative but relevant examples, that help the reader to naturally construct the concepts and provide motivation for the theory in general. In addition, simulations supported by the Python language are  presented.

The aim of this study was to analyze the nearby rural communities to tourist destinations in the state of Quintana Roo from a metatheoretical model of critical approach, and oriented towards alternatives for the development of tourism and based on the dynamic participation and intervention of local actors. The model was applied in 17 communities, which consists of a semi-structured interview, especially designed for workers in the tourism field. The results indicated a different vision than the one contemplated in the diagnoses and analysis of the traditional and current touristic models, since it demonstrates the sensitive direct perception of the communities, especially, the actors that intervene directly in tourist activities. The main challenges of the rural communities must be focused on two aspects: a) to develop sustainable tourism and b) to rescue and diversify their traditional activities. The use of the model works as an axis of analysis on the development of the activity and the impact on the living conditions of the receiving community of the tourist destinations and establishes an excellent beginning, in favor of welfare.

The article analyzes the perception of territory among key agents of local tourism field to investigate how affects the approach to tourism in Ameca, Jalisco, municipality to the west of Mexico marked by migration, whose tourism potential is an alternative for its socioeconomic development. The methodology used is phenomenological, resorting to semi-structured interviews and interpretive analysis to deepen the perception of the participants, complemented by ethnography and documentary analysis to contextualize the place. Results show that, by internalizing socioeconomic and cultural components that affect their experiences in the territory, the agents form a place image that can represent a conditioning factor for tourism development, orienting its dispositions in a negative sense despite any potentiality, also through their perception, endogenous corrective strategies can be found.