Influencia del aditivo eucon 1037 en la resistencia a la compresión de un concreto de f´c= 350 kg/cm2 - Cajamarca

El uso de los aditivos en nuestros días se ha convertido en una práctica muy utilizada para la obtención de concreto con mejores características y que estas se adecuen a las exigencias de la obra o estructura donde este material será utilizado. Uno de los tipos de aditivos más utilizados son los aditivos plastificantes, los cuales presentan una característica fundamental que es la reducción de agua utilizada en la mezcla de concreto, logrando obtener concretos con mayor trabajabilidad con bajas cantidades de agua, permitiendo que la resistencia a la compresión del concreto aumente. El aditivo EUCON 1037 es un aditivo reductor de agua de alto rango que puede ser adicionado al concreto en obra o en una planta de concreto, ese aditivo permite obtener concretos de alta resistencia por trabajar a baja relación agua/cemento, así mismo facilita la colocación permitiendo reducir la mano de obra y permite producir concretos fluidos con resistencias superiores a lo normal. En la presente tesis de investigación se tiene como objetivo principal el determinar la influencia que presenta el adicionar aditivo EUCON 1037 en un concreto de f’c = 350 Kg/cm2 con dosificaciones de 1.2%, 1.4% 1.7% de aditivo por peso de cemento; dosificaciones que se toman a partir de lo que indica la hoja técnica del aditivo cuyo uso es de (0.7% - 1.9% / Kg de cemento). Para ello se realizó la elaboración de especímenes de concreto a partir de una adecuada elaboración de diseños de mezcla, los mismos que fueron sometidos a ensayos a compresión uniaxial, siguiendo los procedimientos de las normas ASTM y NTP correspondientes. Estos diseños de mezcla se elaboraron con agregados de la cantera Acosta (Rio Chonta), que cumple con lo estipulado en las normas correspondientes y que cuyas características físicas serán determinadas en laboratorio, permitiendo la elaboración de los diseños de mezcla. Al finalizar con el trabajo de investigación se llegó a la conclusión que el aditivo EUCON 1037 aumenta considerablemente la resistencia a la compresión de concreto de f’c = 350 Kg/cm2, tal es así que para una dosificación de 1.7% de aditivo por peso de cemento, el aumento con respecto de la mezcla que no presenta ninguna adición es de 28.21% a edad de 7 días y 14.92% a edad de 28 días.Tesi

Reduced Rate of Neural Differentiation in the Dentate Gyrus of Adult Dysbindin Null (Sandy) Mouse

Genetic variations in the gene encoding dysbindin has consistently been associated with schizophrenia and bipolar disorder, although little is known about the neural functions carried out by dysbindin. To gain some insight into this area, we took advantage of the readily available dysbindin-null mouse sandy (sdy−/−) and studied hippocampal neurogenesis using thymidine analogue bromodeoxuridine (BrdU). No significant differences were found in the proliferation (4 hours) or survival (1, 4 and 8 weeks after the last BrdU injection) of progenitors in the subgranular regions of the dentate gyrus between sdy−/− and sdy+/+ (control) mice. However, 4 weeks after the last BrdU injection, a significant reduction was observed in the ratio of neuronal differentiation in sdy−/− when compared to that of sdy+/+ (sdy+/+  = 87.0±5.3% vs. sdy−/−  = 71.3±8.3%, p = 0.01). These findings suggest that dysbindin plays a role during differentiation process in the adult hippocampal neurogenesis and that its deficit may negatively affect neurogenesis-related functions such as cognition and mood

New constraints on the 1922 Atacama, Chile, earthquake from Historical seismograms

International audienc

Seismic Intensities of the 1944 Tonankai Earthquake (M 7.9) (2) : Characteristics of Damage and Phenomena from Supplementary

Earthquake Research Institute (ERI), The University of Tokyo conducted a questionnaire survey immediately after the 1944 Tonankai earthquake. By examining the 290 original questionnaire sheets, Harada et al. (2017) assessed 288 seismic intensity values on the Kawasumi intensity scale (KI-scale). In addition to questions to assess seismic intensity values, the questionnaire survey also requested respondents to make notes in the margins of sheets. In response, 81 questionnaire sheets provided supplementary descriptions, which are valuable because they were recorded by people who experienced the earthquake and suffered from it, and are important for revealing the behavior of seismic waves and the source mechanism of the 1944 Tonankai earthquake. All the supplementary descriptions are reprinted and descriptions of damage, water disturbances, ground deformations, and tsunamis are examined. As a result, the following characteristics are revealed: (1) Damage and ground deformations at high-seismic-intensity observation points are described on the questionnaire sheets. At several points, damage in supplementary descriptions is more severe than in questionnaire responses. Supplementary descriptions show damage was most serious in and around the Suwa Basin, probably due to local amplification of seismic waves in the basin. (2) Sloshing tank water in the Tokyo metropolis and Aichi prefecture was excited by 2-4 sec. period seismic waves. (3) Large-scale ground deformations occurred in the deltas around the river mouths of Kiso, Nagara, and Ibi Rivers in Aichi and Mie prefectures. Boiling soil and cracks due to liquefaction in Kumoi village caused by the 1944 Tonankai earthquake are the only records of liquefaction in Shiga Prefecture. (4) Although 1944 tsunami damage was serious, supplementary descriptions about the tsunami are limited probably because the ERI also conducted a tsunami questionnaire survey on the 1944 Tonankai earthquake

Field Surveys of Tsunami Heights from the 2011 off the Pacific Coast of Tohoku, Japan Earthquake

We report the results of field surveys conducted by the Earthquake Research Institute, to measure tsunami heights from the 2011 off the Pacific coast of Tohoku, Japan Earthquake (M 9.0), on March 11. Measurements were taken at 296 points on the Sanriku coasts of Aomori, Iwate, and Miyagi Prefectures, and the Pacific coasts of Ibaraki and Chiba Prefectures. The data are included in the results of the 2011 Tohoku Earthquake Tsunami Joint Survey Group. We did not cover the Sendai plain in the southern Miyagi Prefecture because other parties extensively measure there, nor Fukushima Prefecture because of the accident of the Fukushima Dai-ichi nuclear power plant. The twelve surveys first sought traces indicating tsunami runup or inundation heights. Reliability was classified into A (most reliable based on clear physical evidence and eyewitness accounts), B (mostly based on natural traces), and C (least reliable based on equivocal evidence). Most physical evidence obtained after June was not significant; therefore, reliance was mostly placed on eyewitness accounts. Locations and relative heights above sea level were measured using handheld GPS receivers, auto-level, or total station. The measured heights were corrected for differences in tide level between measurement time and tsunami arrival time. The results are shown on table and four regional maps; however, the details of each measurement, including locations shown on 1:25,000 maps and photographs of evidence are shown in the Appendix. Along the northern Sanriku coast (Aomori and Iwate), most of the 141 heights range between 10m and 30m. Runup heights exceeding 30m were measured at one location in Noda Village and nine locations in Miyako City. On the southern Sanriku coast in Miyagi, most of the 76 measurements range between 4 and 20 m. On the Ibaraki coast, 36 measurements range from 2.8 to 8.1 m, and the heights generally decease toward the south. On the Chiba coast, 43 measurements range from 0.7 to 7.9 m, with the maximum height near Iioka, Asahi City