Concrete plants consume 10 billion tons of natural aggregates annually from quarries and gravel plants for produce concrete, this demand requires exploiting natural resources from mountains and rivers producing an ecological imbalance. One solution is to use Palm Oil Clinker (POC), which is eliminated in large quantities in the dumps and rivers without taking advantage of its puzolanic, binding and resistance properties as an aggregate in the concrete; another alternative is to apply rubber from abandoned and discarded tires as waste in landfills or burned, without taking advantage of its performance of improvement in concrete, increasing its resistance to impact and fatigue. Unable to find joint POC and rubber information, this research studies its influence replacing 2.5% rubber (grained and crushed) with 10%, 12.5% and 15% POC in the fine aggregate on traditional concrete; results ind...

Objective: To present our experience and assess the recurrence of juvenile nasopharyngeal angiofibroma after a surgical treatment (open versus endoscopic approach) in the country’s northwestern Department of Otorhinolaryngology. Materials and methods: An observational, retrospective, analytical study. The medical records of patients diagnosed with juvenile nasopharyngeal angiofibroma, who were treated at the Department of Otorhinolaryngology – Head and Neck Surgery of this institution from 2014 to 2017, were reviewed. Results: A total of 19 patients diagnosed with juvenile nasopharyngeal angiofibroma underwent a surgical procedure, out of which 14 had an open surgery and 5 an endoscopic one. Recurrence accounted for 50 % and 40 %, respectively, which was not statistically significant (p = 0.88). However, other variables were compared, such as the need for admission to the Intensive C...

El propósito de la presente investigación fue determinar la relación que hay entre la estrategia didáctica juego de roles y la formación por competencias en estudiantes universitarios de administración. Se trabajó mediante una investigación no experimental, correlacional transeccional. La población se conformó por 600 estudiantes, cuya muestra respectiva fue de 234; se aplicó para la recolección de datos un cuestionario. Como principales resultados se tuvo que tanto la estrategia didáctica Juego de roles como la formación de competencias califican a nivel alto, tanto por los estudiantes de primeros ciclos como de los ciclos avanzados. Entre sus conclusiones se tiene que hay una correlación positiva y significativa entre la estrategia didáctica Juego de roles y la Formación por competencias en estudiantes de Administración, según coeficiente de Rho Spearman de 0,714 y u...

La contaminación y a la vez la escasez del agua es considerada una de las preocupaciones principales en el mundo entero. En Perú la mayoría de sus cuencas hidrográficas se ven afectadas por la contaminación proveniente de las actividades productivas y domésticas. La presente investigación buscó analizar el significativo crecimiento de la contaminación del río Moche en el período 2010 a 2020; para ello se realizó un estudio de tipo descriptivo, utilizando el análisis documental mediante el registro de datos de los años 2010 – 2020 de las entidades como la Autoridad Nacional del Agua y otros estudios relacionados; logrando con ello determinar que la contaminación del río Moche no se ha visto reducida en el período de estudio; por el contrario, la existencia de sustancias químicas, minerales y bacterias en el agua se han incrementado exponencialmente en los últimos año...

The fabrication of ultra-sharp tips from carbon fiber (CF), which are mounted on a qPlus probe for combined dynamic scanning tunneling microscopy (STM) and frequency modulation atomic force microscopy (FM-AFM) experiments, is reported. The carbon fiber tips were electrochemically etched in a KOH or NaOH solution, using different electronic devices. CF tips with an apex radius ∼10 nm, as deduced from the measured slopes of the Fowler–Nordheim plots (kR < 70 nm for k ∼ 6), were routinely obtained with a homemade electronic device that controls the intensity of the etching current. Then, these conductive CF tips were also characterized by imaging the 6H-SiC(0 0 0 1) surface covered by an epitaxial graphene layer in ultra-high vacuum (UHV). The lattice of the R30° reconstruction was regularly imaged by STM working either in non-oscillating mode or in dynamic mode, which also maps the ...