Bloques de concreto con emulsión de parafina

The walls of the building often exhibit moisture problems as a result of exposure to rain and water absorption in the soil. Unfortunately, conventional concrete blocks purchased on the market have a high coefficient of capillary suction and a low resistance to water penetration.In this research, concrete blocks and cylinders were produced and analyzed experimentally. They were manufactured with washed concrete sand, type I Portland cement, paraffin wax and a 0,40 water-to-cement (w/c) ratio by weight. Blocks and cylinders were analyzed first without the addition of paraffin wax and then with the addition of 10 %, 20 %, 30 % and 40 % of paraffin wax by weight of the cement. Capillary water absorption test and resistance to water penetration test were completed. A comparative analysis of the results was performed in order to determine the optimum addition of paraffin wax.It was determined that the blocks with paraffin wax have better properties than conventional blocks without additives. Furthermore, it was concluded that the blocks with paraffin wax reduce moisture problems in the walls since these blocks have a low coefficient of capillary suctionLos muros de las edificaciones presentan frecuentemente problemas de humedad como consecuencia de la exposición a la lluvia y la absorción de agua del suelo. Infortunadamente, los bloques de concreto convencionales adquiridos en el mercado tienen coeficientes de absorción capilar altos y resistencias a la penetración de agua bajas.En esta investigación, se produjeron y analizaron experimentalmente bloques y probetas cilíndricas, se fabricaron con arena de concreto lavada, cemento Portland tipo 1, emulsión de parafina y una relación agua-cemento de 0,40 en peso. Se estudiaron bloques y cilindros sin emulsión de parafina y con 10%, 20%, 30% y 40% de adición de emulsión de parafina respecto al peso del cemento. Se ejecutaron ensayos de absorción capilar, de resistencia a la penetración de agua y se realizó un análisis comparativo de los resultados obtenidos para determinar la proporción óptima de adición de emulsión de parafina.Se determinó que los bloques con emulsión de parafina presentan mejores propiedades que los bloques convencionales sin aditivos y que podrían reducir los problemas de humedad en los muros pues tienen un coeficiente de absorción capilar bajo

Synthesis and characterization of new copper phospahate

RESUMEN: Se comparan algunas características fisicoquímicas de los xerogeles conteniendo Cu o Fe soportados en circonia. Se usaron ácido sulfúrico o hidróxido de amonio como catalizadores de hidrólisis durante la etapa de gelación. Los materiales sulfatados cristalizaron principalmente en la fase tetragonal, exhibieron mayor área superficial y presentaron mayor número de sitios ácidos que los catalizadores preparados en medio básico. La adición de los precursores de hierro y cobre en el gel de síntesis durante la preparación de la circonia sulfatada, condujo a una mayor estabilización de las especies sulfato en dicho soporte, especialmente bajo condiciones oxidantes

Reflexiones sobre el proceso de admisión de la Universidad de Antioquia, a propósito de una experiencia de intervención social

Este artículo da cuenta de una experiencia de intervención social con los bachilleres aspirantes a la universidad de antioquia, durante el segundo semestre de 1999. Ante el diagnóstico, de los autores, de poca solidaridad brindada por la institución a estos ciudadanos, se propuso una intervención caracterizada por el tratamiento solidario a los aspirantes durante el examen de admisión y se propusieron dos hipótesis: la primera, que los intervenidos tendran un mejor desempeño con relación a los controles y la segunda, que los primeros se llevarían una mejor imágen de la institución (esta última no sería puesta a prueba en esta oportunidad). Los datos negaron la primera hipótesis. En los análisis se tuvo acceso a los resultados del ICFES y estos revelaron lo que parece ser un sesgo en la selección de carrera, pues parece ser el resultado del ICFES el que orienta la decisión

Phasic flow patterns of right versus left coronary arteries in patients undergoing clinical physiological assessment

BACKGROUND: Coronary blood flow in humans is known to be predominantly diastolic. Small studies in animals and humans suggest that this is less pronounced or even reversed in the right coronary artery (RCA). AIMS: This study aimed to characterise the phasic patterns of coronary flow in the left versus right coronary arteries of patients undergoing invasive physiological assessment. METHODS: We analysed data from the Iberian-Dutch-English Collaborators (IDEAL) study. A total of 482 simultaneous pressure and flow measurements from 301 patients were included in our analysis. RESULTS: On average, coronary flow was higher in diastole both at rest and during hyperaemia in both the RCA and LCA (mean diastolic-to-systolic velocity ratio [DSVR] was, respectively, 1.85±0.70, 1.76±0.58, 1.53±0.34 and 1.58±0.43 for LCArest, LCAhyp, RCArest and RCAhyp, p<0.001 for between-vessel comparisons). Although the type of RCA dominance affected the DSVR magnitude (RCAdom=1.55±0.35, RCAco-dom=1.40±0.27, RCAnon-dom=1.35; standard deviation not reported as n=3), systolic flow was very rarely predominant (DSVR was greater than or equal to 1.00 in 472/482 cases [97.9%] overall), with equal prevalence in the LCA. Stenosis severity or microvascular dysfunction had a negligible impact on DSVR in both the RCA and LCA (DSVR x hyperaemic stenosis resistance R2 =0.018, p=0.03 and DSVR x coronary flow reserve R2 <0.001, p=0.98). CONCLUSIONS: In patients with coronary artery disease undergoing physiological assessment, diastolic flow predominance is seen in both left and right coronary arteries. Clinical interpretation of coronary physiological data should therefore not differ between the left and the right coronary systems

Phasic flow patterns of right versus left coronary arteries in patients undergoing clinical physiological assessment

BACKGROUND: Coronary blood flow in humans is known to be predominantly diastolic. Small studies in animals and humans suggest that this is less pronounced or even reversed in the right coronary artery (RCA). AIMS: This study aimed to characterise the phasic patterns of coronary flow in the left versus right coronary arteries of patients undergoing invasive physiological assessment. METHODS: We analysed data from the Iberian-Dutch-English Collaborators (IDEAL) study. A total of 482 simultaneous pressure and flow measurements from 301 patients were included in our analysis. RESULTS: On average, coronary flow was higher in diastole both at rest and during hyperaemia in both the RCA and LCA (mean diastolic-to-systolic velocity ratio [DSVR] was, respectively, 1.85±0.70, 1.76±0.58, 1.53±0.34 and 1.58±0.43 for LCArest, LCAhyp, RCArest and RCAhyp, p<0.001 for between-vessel comparisons). Although the type of RCA dominance affected the DSVR magnitude (RCAdom=1.55±0.35, RCAco-dom=1.40±0.27, RCAnon-dom=1.35; standard deviation not reported as n=3), systolic flow was very rarely predominant (DSVR was greater than or equal to 1.00 in 472/482 cases [97.9%] overall), with equal prevalence in the LCA. Stenosis severity or microvascular dysfunction had a negligible impact on DSVR in both the RCA and LCA (DSVR x hyperaemic stenosis resistance R2 =0.018, p=0.03 and DSVR x coronary flow reserve R2 <0.001, p=0.98). CONCLUSIONS: In patients with coronary artery disease undergoing physiological assessment, diastolic flow predominance is seen in both left and right coronary arteries. Clinical interpretation of coronary physiological data should therefore not differ between the left and the right coronary systems

Combined Assessment of FFR and CFR for Decision Making in Coronary Revascularization: From the Multicenter International ILIAS Registry

OBJECTIVES The aim of this study was to demonstrate the clinical implications of combined assessment of fractional flow reserve (FFR) and coronary flow reserve (CFR).BACKGROUND Combined assessment of FFR and CFR allows detailed characterization of pathophysiology in chronic coronary syndromes. Data on the clinical implications of distinct FFR and CFR patterns are limited, leading to uncertainty regarding their relevance.METHODS Patients with chronic coronary syndromes and obstructive coronary artery disease were selected from the multicenter ILIAS (Inclusive Invasive Physiological Assessment in Angina Syndromes) registry. Patients were classified into 4 groups on the basis of FFR &lt;0.80 and CFR &lt;2.0. The endpoint was the 5-year target vessel failure (TVF) rate.RESULTS A total of 2,143 patients with 2,725 lesions were included. Compared with normal FFR/normal CFR, low FFR/low CFR carried the highest risk for TVF (HR: 5.4; 95% CI: 3.2-9.3; P &lt; 0.001), significantly higher than in revascularized vessels (P = 0.007). Discordance, with either low FFR/normal CFR or normal FFR/low CFR, was associated with increased TVF rates compared with normal FFR/normal CFR (low FFR/normal CFR: HR: 3.5 [95% CI: 2.2-5.4; P &lt; 0.001]; normal FFR/low CFR: HR: 3.0 [95% CI: 1.9-4.7; P &lt; 0.001]). No difference in 5-year TVF was observed between the 2 discordant groups (P = 0.57) or between the discordant groups and the revascularized group (P = 0.26 vs low FFR/normal CFR; P = 0.60 vs normal FFR/low CFR).CONCLUSIONS Impaired coronary hemodynamics are uniformly associated with increased 5-year TVF rates. Nonrevascularized vessels with discordant FFR and CFR are associated with 5-year event rates that are equivalent to those of vessels that undergo revascularization, whereas vessels with combined low FFR and CFR exhibit event rates that are significantly higher than after revascularization. (C) 2022 by the American College of Cardiology Foundation

Combined Assessment of FFR and CFR for Decision Making in Coronary Revascularization: From the Multicenter International ILIAS Registry

Objectives: The aim of this study was to demonstrate the clinical implications of combined assessment of fractional flow reserve (FFR) and coronary flow reserve (CFR). Background: Combined assessment of FFR and CFR allows detailed characterization of pathophysiology in chronic coronary syndromes. Data on the clinical implications of distinct FFR and CFR patterns are limited, leading to uncertainty regarding their relevance. Methods: Patients with chronic coronary syndromes and obstructive coronary artery disease were selected from the multicenter ILIAS (Inclusive Invasive Physiological Assessment in Angina Syndromes) registry. Patients were classified into 4 groups on the basis of FFR ≤0.80 and CFR <2.0. The endpoint was the 5-year target vessel failure (TVF) rate. Results: A total of 2,143 patients with 2,725 lesions were included. Compared with normal FFR/normal CFR, low FFR/low CFR carried the highest risk for TVF (HR: 5.4; 95% CI: 3.2-9.3; P < 0.001), significantly higher than in revascularized vessels (P = 0.007). Discordance, with either low FFR/normal CFR or normal FFR/low CFR, was associated with increased TVF rates compared with normal FFR/normal CFR (low FFR/normal CFR: HR: 3.5 [95% CI: 2.2-5.4; P < 0.001]; normal FFR/low CFR: HR: 3.0 [95% CI: 1.9-4.7; P < 0.001]). No difference in 5-year TVF was observed between the 2 discordant groups (P = 0.57) or between the discordant groups and the revascularized group (P = 0.26 vs low FFR/normal CFR; P = 0.60 vs normal FFR/low CFR). Conclusions: Impaired coronary hemodynamics are uniformly associated with increased 5-year TVF rates. Nonrevascularized vessels with discordant FFR and CFR are associated with 5-year event rates that are equivalent to those of vessels that undergo revascularization, whereas vessels with combined low FFR and CFR exhibit event rates that are significantly higher than after revascularization. (Inclusive Invasive Physiological Assessment in Angina Syndromes Registry [ILIAS Registry]; NCT04485234