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

The general objective of this study was to design a periodic maintenance plan for Paradero Las Retamas - Puente Los Angeles section of the Central highway, developed in 2021. For this purpose, a quantitative, descriptive, non-experimental, cross-sectional approach methodology was applied to a sample population of 1,9 km distributed in 13 sampling units of 230,42 m2, to which the Pavement Condition Index (PCI) was determined according to its own methodology. A traffic study was also conducted to determine the composition and classification of vehicles, and the drainage system was inspectedto identify the current pavement conditions. In addition, physical properties were analysed through laboratory tests to determine the International Regularity Index (IRI) and the Present Serviceability Index (PSI), considering the stipulations ofthe Ministry of Transportation and Communications (MTC). Finally, the information was processed using HDM-4 software to determine the most appropriate periodic maintenance strategies. In this way, an overall PCI of 62 was obtained, qualified as “good”, and an Average Daily Annual Index (IMDA) of 31 236 vehicles/day, which classifies the road as a first-class highway. On the other hand, the most viable maintenance alternative was a simple surface treatment, accompanied by the uniform application of a layer of bituminous binder on the granular pavement, combined with an optimal routine maintenance. The evaluation criteria show the profitability of the project, showing a Net Present Value (NPV) of 3,20 million soles (844 804 USD) and an Internal Rate of Return (IRR) of 20 %. Finally, a positive impact on the PSI is obtained as a result of the implementation of the alternative. 

The objective of this research was to develop a cold mix design for the stabilization of a recycled soil with slow breaking cationic asphalt emultion with low viscosity and higher degree of hardness (CSS-1h), based on the Modified Marshall design method. The work consisted in extracting soil samples from a deteriorated pavement for the elaboration of briquettes with emultion percentages between 3% and 6% varying in intervals of 0.5%, then these were tested for the calculation of the volumetric and mechanical properties, to finally determine the optimal percentage of emultion. The maximum resistance (stability) of the mixture was obtained with a dosage of 4.8% asphalt emultion and 2.88% asphalt residue, achieving a maximum value of 980 kg. In conclusion, the stabilization of the material with the proposed dosage led to good results, complying with the minimum stability of 227 kg (500 lb) required by the specifications of the Highway Manual EG-2013.

The highways that connect the populated centers of the city of Puno in Peru, lack of paved roads, most of the connecting roads are carriageable trails. In addition, these roads make it difficult for vehicles to move continuously and safely due to the presence of holes and deformation caused by rain. Then, the purpose of this research was to determine the effect of the combination of quinoa ash and lime as soil stabilizers. The samples and data were processed using applied methodology, pure experimental design, and quantitative approach. The results showed an improvement in the characteristics of cohesive soils after adding quinoa ash and lime. With the addition of 9 % quinoa ash and 5 % lime, a small variation of the liquid limit, plastic limit and plasticity index was obtained in comparison with the foundation soil. Similarly, in terms of dry density and moisture content, a decrease in the optimum moisture content of 9 % was obtained, and an increase in the dry density of 1,902 g/cm3. The CBR increased reaching values of 32,0 % at 100 % dry density and at 95 % dry density showed a value of 25,6 %. It is concluded that there is an improvement in the mechanical properties of the soil with the addition of quinoa ash and lime.

This paper presents problems of mass removal caused by excessive rains on National Road 40, San Carlos de Bariloche-El Bolsón section, in the southwest of the province of Río Negro, in Patagonia, Argentina, bordering Guillelmo Lake. The zone in question presents copious precipitations that affect hills, whose slopes have suffered forest fires, that have left them without vegetation and susceptible to erosion. The aforementioned problems obliged Vialidad Nacional to make an order to the School of Mountain Roads Engineering to solve this problem that is becoming chronic and whose severity increases with each climatic event. In effect, after each rain, large volumes of debris accumulate on the road cutting the route, and cutting off the link between the cities of San Carlos de Bariloche and El Bolsón, generating a great amount of difficulties to the region. Firstly, measures tending to alleviate this problem in the short term are proposed, and further works in order to achieve a fundamental solution to solve this serious problem definitely.

Balanced diets for tilapias are based mainly on fishmeal, soybean meal, and other high-cost protein ingredients, making Eisenia fetida an alternative for protein substitution in feeds for these species. The objective of this research was to evaluate the effect of the substitution of the red earth worm (Eisenia fetida) in the diet of tilapia fingerlings (Oreochromis aureus) on zootechnical parameters, body indices, and chemical composition in fish carried up to the fattening phase. In the Aquaculture Module of the Alfredo Volio Mata Experimental Station (EEAVM), between May and September 2021, 8 hormonally reversed fingerlings were stocked per tank (8 tanks in total) with an initial average weight of 3.24 g ± 0.09 g. In the initial phase, two treatments were used, the control treatment (T0) and the treatment with a 50% substitution of balanced feed for the dehydrated earth worm (T1) in dry matter. In the fattening phase, the same experimental units were used, but the feed was 100% based on commercial diet. The effect of this substitution was evaluated on weight gain, increase in standard length and width, specific growth rate (SGR), feed conversion ratio (FCR), thermal growth coefficient (CTC), protein use efficiency (PER), gonadosomatic index (IGS), hepatosomatic index (IHS), viscerosomatic index (VIS), head/body ratio and final chemical composition of the fish tissue. In weight gain, increase in standard length and width, SGR, CTC, PER, IHS, IGS, and chemical composition of the tissues, no significant differences were observed (p>0.05); where as in the FCR, IVS, and head/body ratio, significant differences were obtained (p<0.05).

This work aimed to evaluate the inclusion of different levels of arboreal foliage in the voluntary consumption of dry matter and the blood metabolic profile of lambs. It was developed at Havana, Cuba's "Villena Revolución" pasture and forage station. Twenty-four weaned lambs of the pelibuey breed were used, at 84 ± 9.75 days of age and an average live weight of 15.80 ± 2.74 kg, distributed in six groups with a completely randomized design (DCA) for 120 days. The treatments consisted of the inclusion in the totally mixed ration (RTM) in two levels (20.40%) of arboreal foliage (Tithonia diversifolia, Morus alba, Leucaena leucocephala) in substitution (80.60%) of Cenchrus purpureus hybrid Cuba OM-22, which was offered on a single occasion (08:30 a.m.) at a rate of 12% wet basis (BH) of live weight. The mixtures were isoenergetic, but not isoproteic. Blood biochemical indicators (glucose, cholesterol, triglycerides, urea, creatinine) and hematological (hemoglobin, hematocrit) were determined. Dry matter intake was higher (1.31 vs. 1.37 kg/d, p<0.0001) when 40% of mulberry and Leucaena foliage participated in the mix. Within the blood profile, glucose, creatinine, hemoglobin, and hematocrit were below the physiological limits for the species, while cholesterol, triglycerides, and urea were within the normal range. It was concluded that the inclusion of 40% of mulberry and Leucaena in the mixture with Cenchrus hybrid purpureus Cuba OM-22, improved dry matter intake and maintained an influence on the sanguine metabolic profile.  

The effect of the inclusion of β-mannanase in feed for early lactating dairy cows on a commercial farm in the Oreamuno area of Cartago, Costa Rica was evaluated. Twenty-seven grazing Jersey cows were used, distributed based on milk production, days in lactation, and number of lactations in 3 experimental groups: 0%, 0.1%, and 0.2% inclusion of the β-mannanase enzyme. The variables analyzed were milk production (kg/day), milk corrected to 4% fat, percentage and kilograms of total solids, fat, protein, lactose, non-fat solids, somatic cell count (cs/ml), calcium (Ca), phosphorus (P), magnesium (Mg) and milk ureic nitrogen (MUN). A repeated measures analysis was carried out with a mixed linear model analyzed with the SAS statistical software and a Tukey test to determine the significance (p<0.05) of the possible effects of the use of the β-mannanase enzyme. No significant differences were found for any of the variables evaluated (p˃0.05), this was associated with the low mannan-oligosaccharides content of the experimental diet (21.12-29.46 g/animal/day). Therefore, it is concluded that under the conditions of this experiment, no effect of the inclusion of the enzyme β-mannanase in the diet of Jersey cows in early lactation was observed.

In rural communities, families usually reared animals in the backyards of their houses in the south of México. The diet of those animals comprises forages and products from milpa. Milpa is a traditional Maya agriculture system where many crops are cultivated, including pigeon pea (Cajanus cajan) a legume with high protein content. The objective of this study was to evaluate the effect of C. Cajan in diets of naked neck growing pullets on productive performance. Three diets were formulated with 25% of C. cajan: soaked in a solution of CaOH (S); soaked in a solution of CaOH and boiled (SB); germinated (G), and a control diet (C) based on maize and soybean meal. Seventy-two pullets seven days old were used.  Feed intake, weight gain, and feed conversion were recorded. Data were analyzed with an ANOVA for a random design. There were no statistical differences among treatments for feed intake and daily weight gain (p>0.05) (Average of 63.3 and 36.5 g/bird/day for feed intake and daily weight gain, respectively). Feed conversion in treatment G was higher (1.82) than in the other treatments (1.70 for treatments S, SB, and C) (p<0.05). Results suggest that feed intake and daily weight gain were not affected by the inclusion of C. cajan in the pullet’s diets. However, feed conversion was higher in treatment G in comparison to the other treatments.

Current research highlighted the importance to recognize feasible biomarkers for early diagnoses and treatment in oral cancer. Our study analyzed the expression and spatial distribution of ALDH1A1, FGFR2, caspase-3, and CD44 in Oral Squamous Cell Carcinoma (OSCC) and leukoplakia with and without oral mucosal dysplasia. Paraffin-embedded samples of OSCC (n=5), leukoplakia with (n=5) and without (n=5) dysplasia obtained by incisional biopsies were processed using conventional histochemical techniques. Immunohistochemistry was performed using antibodies against ALDH1A1, FGFR2, caspase-3, and CD44. Images of the immunohistochemically stained tissue sections were analyzed according to the intensity of the immunostaining of each marker and classified in Scores. The Kruskal-Wallis test was performed (p≤0.05). Our results demonstrated a statically difference in the expression of all immunomarkers between OSCC and leukoplakia without dysplasia, being more significant in FGFR2 and ALDH1A1. Within the limitations of this study, our data showed that all biomarkers were overexpressed in OSCC and leukoplakia with oral mucosa dysplasia, suggesting that the presence of dysplasia is a significant clinic-pathologic predictor for malignant transformation.

The first objective of this research was to evaluate the effectiveness of XP-Endo Finisher on dentinal tubule penetration of irrigation solution using confocal laser scanning microscopy. The main purpose of this research was to compare the effect of cold lateral condensation, continuous wave obturation and core-carrier based techniques on sealer penetration. Sixty mandibular premolars were prepared and allocated into two experimental groups (n=30) as the final irrigation technique and obturation technique experiment. In the final irrigation technique experiment, final irrigation was performed with XP-Endo Finisher, passive ultrasonic irrigation (PUI) and conventional needle irrigation (CNI) (n=10). The roots in the obturation technique experiment were also assigned into 3 groups and obturated with cold lateral condensation, continuous-wave obturation and core-carrier techniques (n=10). The most effective activation method, which emerged as a result of the first part of this study, was used as the final irrigation method in the obturation technique experiment. Then, all roots were sectioned in 1-mm-thick slices at 3mm from the apex for scanning. In terms of depth and percentage of material penetration, CNI exhibited significantly the lowest values and no significant difference was found between others. Also, there was no significant difference among obturation methods. In conclusion, XP-Endo Finisher and PUI are more effective than CNI on irrigant penetration. Sealer penetration into dentinal tubules is independent of obturation techniques.