ABSTRACT
The authors would like to make a correction in a recently published paper [...].
ABSTRACT
The addition of a range of micro- and nano-particles to high-performance concrete has been the focus of recent research. At present, studies are mainly aimed at designing customised mortars, providing them with specific properties for each application. Improving the durability of mortars is one of the main objectives in such research, as a result of increasing environmental concern. The research presented herein analyses the synergistic effect of nanosilica and metakaolin as additives on the service life of cement-based mortars subject to aggressive environments (i.e., chloride exposure) at early ages. The effects of the additives on the durability properties of submerged samples after two and three days of curing were analysed. Tests were conducted on several different properties: resistivity, porosity, mechanical properties, chloride diffusion, and service life. It is observed that metakaolin and nanosilica exhibit a synergistic effect as additives, which is related to porosity refinement and chloride ion binding capacity, which contributes to enhanced resistance against chloride penetration from very early ages.
ABSTRACT
Research on early stages of corrosion of steel bars caused by chloride penetration is relevant in improving the durability of reinforced concrete structures. Similarly, the formation and development of cracks induced in the surrounding concrete is also of great importance. This paper uses integration of the analytical models examined in the published literature, combined with experimental research in corrosion induced at the concrete/steel interface, in estimating the time-to-crack initiation of reinforced concrete subjected to corrosion. This work studies the influence of the porous network and electric current density on the cracking process at early ages. The experimental program was performed by using an accelerated corrosion test. Two types of concrete were performed: A conventional concrete (CC) and a concrete with silica fume (SFC). A current density of 50 µA/cm2 and 100 µA/cm2 was applied to specimens of both concretes. Examination performed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) provided both qualitative and quantitative information on the penetration of the rust layer in the surrounding concrete porous network. Strain gauges were used to measure corrosion-induced deformations between steel and concrete matrices, as well as the formation of corrosion-induced cracks. A good correlation between the rate of penetration of the rust products in the surrounding pores and the delay of the cracking pressure in concrete was observed from the experimental results. This phenomenon is incorporated into the analytical model by using a reduction factor, which mainly depends on the pore size of the concrete. The crack width obtained exhibited a significant dependency on electric current density at the beginning of the test, depending mainly on the pore size of the concrete later.
ABSTRACT
La deficiencia de antitrombina III hereditaria es una rara enfermedad que afecta al 0.02-0.2 por cento de la población. Puede presentar mayor frecuencia de complicaciones y resultados adversos tanto en la madre como en el feto. Se presenta el manejo obstétrico de dos gestaciones consecutivas en una mujer con deficiencia de antitrombina III. Descripción: en ambos embarazos la madre realiza profilaxis de la enfermedad tromboembólica con heparina de bajo peso molecular para evitar la aparición de esta patología tanto en el embarazo como en el puerperio y mejorar el flujo útero-placen-tario. Con respecto a las complicaciones obstétricas, sólo existe un enlentecimiento del crecimiento fetal que obliga a un control obstétrico estricto. En ambas gestaciones los estudios eco-Doppler están dentro de la normalidad lo que permite una conducta expectante, consiguiendo llegar a término. Discusión: la profilaxis con heparina de bajo peso molecular en las gestantes con esta trombofilia y las intervenciones preventivas de factores de riesgo de enfermedad tromboembólica, junto con un control obstétrico adecuado, ha conseguido evitar la apari-ción de complicaciones derivadas de esta patología en el embarazo y en el puerperio. Por otra parte, el control del crecimiento fetal y el estudio Eco-Doppler han permitido asegurar el bienestar fetal no adelan-tando el parto, consiguiendo partos a término...
Hereditary antithrombin III deficiency is a rare disease that affects 0.02-0.2 percent of the population. It may be associated with a higher rate of complications and adverse outcomes in both mother and fetus. The present study describes the management of a woman with antithrombin III deficiency and two consecutive pregnancies. Description: in both pregnancies, the woman under went prophylaxis with low molecular weigh heparin, to prevent thromboembolic disease and improve the utero-placental flow during pregnancy and the postpartum period. The only obstetric compli-cation was fetal growth retardation requiring strict obstetric control. In these two cases the eco-Doppler studies offeto-placentalflow were normal, leading to the expectation of managing a term birth. Discussion: low molecular weigh heparin prophylaxis in pregnant women with thrombophilia and preventive interventions for risk factors for throm-boembolic disease, together with appropriate obstetric care managed to avoid the emergence of complications of this disease in pregnancy and puer-perium. Fetal growth control and a Doppler study also help to ensure the well-being of the fetus and avoid a preterm birth...
Subject(s)
Humans , Female , Pregnancy , Antithrombin III Deficiency/prevention & control , Pregnancy, High-Risk , Fetal Growth Retardation , Venous Thromboembolism/prevention & controlABSTRACT
Introducción: La incidencia de gestación ectópica es 20/1000 embarazos. La mola hidatiforme ocurre en 1/1000 embarazos. Los casos de mola hidatiforme en embarazos ectópicos albergados en las trompas de Falopio constatados en la literatura mundial son excepcionales. Objetivo: Presentamos un caso clínico de embarazo ectópico molar tubárico y revisión de la literatura. Conclusión: La enfermedad trofoblástica gestacional asociada a embarazo ectópico es un entidad extremadamente rara que debe tenerse en cuenta por su trascendencia.
Introduction: The incidence of ectopic pregnancy is 20/1000 pregnancies. The hidatidyform mole occurs in about 1/1000 pregnancies. The cases of hidatidyform mole in ectopic pregnancies located in the Fallopian tube collected in world literature are exceptional. Objective: We present a clinical case of an ectopic molar pregnancy in the tubes and a literature review. Conclusion: The trophoblastic pregnancy disease associated to an ectopic pregnancy is an extremely rare entity that should be considered because of its transcendence.
Subject(s)
Humans , Adult , Female , Pregnancy , Pregnancy, Tubal/surgery , Pregnancy, Tubal/diagnosis , Hydatidiform Mole/surgery , Hydatidiform Mole/diagnosis , Uterine Neoplasms/surgery , Uterine Neoplasms/diagnosis , LaparoscopyABSTRACT
El linfoma B difuso de células grandes es un linfoma no Hodgkin de fenotipo B y gran agresividad, con una diseminación a ovario del 7 por ciento. Su presentación de forma primaria en ovario es muy poco común, representando el 0,5 por ciento de todos los linfomas no Hodgkin y el 1,5 por ciento de todos los tumores de ovario. En este caso se presenta una paciente con clínica de dolor y distensión abdominal con una masa pélvica palpable, estableciéndose posteriormente el diagnóstico de linfoma B difuso de células grandes bilateral de ovario. En determinadas situaciones resulta complicado diferenciar el origen primario o secundario de la neoplasia. Los linfomas primarios localizados en ovario tienen un mejor pronóstico que los secundarios diseminados a ovario cuyo pronóstico es más sombrío. Sin embargo la mayoría de los casos publicados están basados en tratamiento quimioterápico previo a la era de rituximab.
The diffuse large B-cell lymphoma is a highly aggressive phenotype B non-Hodgkin lymphoma which is characterized by 7 percent dissemination in the ovary. Its presentation in primary form in the ovary is very uncommon and accounts for 0.5 percent of all lymphomas. In this case, the patient presents symptoms of pain and abdominal strain with a palpable pelvic mass and a post-diagnosis of bilateral diffuse large B-cell lymphoma in the ovary. In certain situations, it is complicated to differentiate between the primary and secondary origin of the neoplasia. The primary lymphomas located in the ovary have a better prognosis than secondary lymphomas whose prognosis is more uncertain. However, the majority of published cases are subjected to chemothe-rapeutic treatment prior to rituximab.
