Inhibiting behavior of nitrites in corrosion of reinforcing steel in basic solutions simulating the electrolytic environments of micropores concrete in the initiation period

Measurements of the corrosion rate of corrugated steel bars have been carried out in solutions simulating electrolitic chloride enviroments in the micropores of concrete in the initiation period. It has been studied the effect of sodium nitrite as a corrosion inhibitor when added to the mentioned solutions. The solutions for the experiments were prepared by addition of different volumes of FeCl2 0.2 M into a saturated solution of calcium hydroxide until the target pH was reached in each case. This is the soluble compound produced during the corrosion of steel as a result of chloride attack.. It has been observed a significant improvement in using nitrite as inhibiting agent in these systems, but its efficiency decreases when the pH is reduced. The corrosion seems to be related to the [Cl - ]/[OH - ] ratio in three different regions of pH identified from acid to alkaline pH value

Estudio de la respuesta de plantas de pepino (Cucumis Sativbus L. CV). Hyclos) a diferentes relaciones NO3/NH4+

Cucumber plants were hydroponically grown in a greenhouse with four N03-/NH4+ ratios (100/0, 80/20, 60/40 and 30/70), in order to study their tolerance to NH/ supply. Plants grown in 60/40 N03- /NH/ solution displayed higher weight than N03- treated plants. By contrast, plants grown with N03-/NH4+ ratios of 80/20 and 30/70 showed lower growth than plants fed with N03- as the sole source of N. As the proportion of NH4+ in the nutrient solution was increased Ca, Mg, Mn and B in the leaf and Ca and Mg in the root decreased, whereas P, K, and Zn concentrations in the leaf and Fe, B and Zn levels in the root increased. Finally, NH/ supplied in low and high concentrations was harmful to cucumber plants cv. Hyclos development, whereas it is really efficient when N03- and NH4+ are supplied in about equivalent amounts (60/40).En este trabajo se estudia la respuesta de plantas de pepino a diversas relaciones N03-/NH4+ (100/0, 80/20, 60/40, 30/70), al objeto de comprobar el grado de tolerancia de esta especie vegetal a concentraciones crecientes de NH4 + en el medio de cultivo. Las plantas cultivadas con la relación 60/40 presentaron un peso superior a las testigo (100/0). Por el contrario, las sometidas a las relaciones 80/20 y 30/70 ofrecieron una reducción en el crecimiento. A medida que aumenta el aporte de NH4+ disminuye la concentración de Ca, Mg, Mn y B en hoja, de Ca y Mg en raíz y aumenta la concentración de P, K Y Zn en hoja y de Fe, B y Zn en raíz. Finalmente a las plantas de pepino cv. Hyclos no les beneficia el NH4+ cuando la mayor parte del N está como N03- (80/20); les resulta eficaz el catión cuando se suministra en concentraciones casi equivalentes a las de N03-, a la vez que niveles muy altos de NH4+ (70%) causan efectos perjudiciales

Estudio de la velocidad de corrosión de aceros embebidos en morteros de cemento sustituidos con residuo de catalizador de craqueo catalítico (FC3R)

This paper reports on a study of the corrosion levels in steel bars embedded in mortars made with a blend of Portland cement and (0-20%) spent fluid catalytic cracking catalyst residue (FC3R), with a variable (0.3-0.7) water/binder (w/b) ratio. The specimens were stored in the following conditions: relative humidity of 40, 80 or 100% and CO2 concentrations of 5 and 100%. The steel corrosion rate was measured with polarization resistance techniques. In the absence of aggressive agents, the steel was found to remain duly passivated in mortars with an FC3R content of up to 15% under all the conditions of relative humidity tested. The reinforcement corrosion level in mortars with a w/b ratio of 0.3 and 15% FC3R subjected to accelerated carbonation was similar to the level observed in the unblended Portland cement control mortar.En este trabajo se ha estudiado el nivel de corrosión de barras de acero embebidas en morteros de cemento Portland con relación agua/material cementante (a/mc) variable (0,3-0,7), en los que parte del cemento (0-20%) se sustituyó por catalizador de craqueo usado (FC3R). Las condiciones de conservación de las probetas elaboradas fueron las siguientes: distintas humedades relativas (40, 80 y 100%) y dos concentraciones de CO2 (5 y 100%). La velocidad de corrosión de los aceros se midió mediante la técnica de resistencia de polarización. Se ha podido determinar que, bajo las distintas condiciones de humedad relativa y ausencia de agresivo, los aceros se mantuvieron correctamente pasivados en los morteros con contenidos de FC3R de hasta el 15%. El nivel de corrosión que presenta el refuerzo embebidos en morteros con sustitución de un 15% de cemento por FC3R y relación a/mc 0,3, al ser sometidos a un proceso de carbonatación acelerada, era muy similar al mostrado por el mortero patrón, sin FC3R

Estudio de la respuesta de plantas de pepino (Cucumis Sativbus L. CV). Hyclos) a diferentes relaciones NO3/NH4+

En este trabajo se estudia la respuesta de plantas de pepino a diversas relaciones N03-/NH4+ (100/0, 80/20, 60/40, 30/70), al objeto de comprobar el grado de tolerancia de esta especie vegetal a concentraciones crecientes de NH4 + en el medio de cultivo. Las plantas cultivadas con la relación 60/40 presentaron un peso superior a las testigo (100/0). Por el contrario, las sometidas a las relaciones 80/20 y 30/70 ofrecieron una reducción en el crecimiento. A medida que aumenta el aporte de NH4+ disminuye la concentración de Ca, Mg, Mn y B en hoja, de Ca y Mg en raíz y aumenta la concentración de P, K Y Zn en hoja y de Fe, B y Zn en raíz. Finalmente a las plantas de pepino cv. Hyclos no les beneficia el NH4+ cuando la mayor parte del N está como N03- (80/20); les resulta eficaz el catión cuando se suministra en concentraciones casi equivalentes a las de N03-, a la vez que niveles muy altos de NH4+ (70%) causan efectos perjudiciales.STUDY OF CUCUMBER PLANT RESPONSE TO N03- /NH4 + RATIOS Cucumber plants were hydroponically grown in a greenhouse with four N03- /NH/ ratios (100/0, 80/20, 60/40 and 30/70), in order to study their tolerance to NH/ supply. Plants grown in 60/40 N03- /NH/ solution displayed higher weight than N03- treated plants. By contrast, plants grown with N03- /NH/ ratios of 80/20 and 30/70 showed lower growth than plants fed with N03- as the sole source of N. As the proportion of NH/ in the nutrient solution was increased Ca, Mg, Mn and B in the leaf and Ca and Mg in the root decreased, whereas P, K, and Zn concentrations in the leaf and Fe, B and Zn levels in the root increased. Finally, NH/ supplied in low and high concentrations was harmful to cucumber plants cv. Hyclos development, whereas it is really efficient when N03• and NH/ are supplied in about equivalent amounts (60/40)

Synthesis and gas adsorption properties of mesoporous silica-NH2-MIL-53(Al) core-shell spheres

Ordered mesoporous silica-NH2-MIL-53(Al) core-shell spheres of about 4 µm in diameter have been synthesized by seeding the corresponding mesoporous silica spheres (MSSs) with crystals of NH2-MIL-53(Al) and subsequent secondary crystal growth into a MOF shell. The morphology of the particles was analyzed by SEM, while TGA, EDX and XRD characterizations gave information on the composition and structure of this material and the activation of the MOF. N2 adsorption analysis revealed that the NH2-MIL-53(Al) shell controlled the access of guest molecules into the hydrophilic silica mesoporous structure, while the breathing behavior of the microporous NH2-MIL-53(Al) shell was confirmed by CO2 adsorption isotherms

Outstanding aspects on the use of spent FCC catalyst in binders

4 pages, 3 fiures, 7 tables.-- En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.FCC is a waste material from petrochemical plants which has interesting properties for preparing binders. FCC is lightly grey in color, and white FCC-portland cements with L*≥85 can be prepared. FCC reactivity is enhanced by grinding and it is attributed to pozzolanic reaction towards lime. Stratlingite is the main hydrated product from pozzolanic reaction, and CSH and CAH are also formed. Reactivity of FCC is high, and low curing temperature does not affect this contribution to strength in hardened mixtures. Additionally, high strength concrete can be easily prepared, and compressive strength greater 100MPa can be reached. Mixtures with low w/b ratio showed good behaviour in carbonation tests.Authors thank to Ministerio de Ciencia y Tecnología of Spain and FEDER the financial support of MAT 2001-2694 and BIA 2004-0052 projects.Peer reviewe

Función de apantallamiento de interferencia electromagnética de pastas de cemento con materiales carbonosos y cenizas volantes procesadas

The study described in this article explored the effect of adding different types of carbon materials (graphite powder and three types of carbon fibre), fly ash (with 5.6%, 15.9% and 24.3% Fe2O3), and a mix of both on electromagnetic interference (EMI) shielding in Portland cement pastes. The parameters studied included the type and aspect ratio of the carbonic material, composite material thickness, the frequency of the incident electromagnetic radiation and the percentage of the magnetic fraction in the fly ash. The findings showed that the polyacrylonitrile-based carbon fibres, which had the highest aspect ratio, provided more effective shielding than any of the other carbon materials studied. Shielding was more effective in thicker specimens and at higher radiation frequencies. Raising the magnetic fraction of the fly ash, in turn, also enhanced paste shielding performance. Finally, adding both carbon fibre and fly ash to the paste resulted in the most effective EMI shielding as a result of the synergies generated.En el presente trabajo se investiga la influencia de la adición de diferentes tipos de materiales carbonosos (polvo de grafito y 3 tipos de fibra de carbono), de una ceniza volante con diferentes contenidos de fase magnética (5,6%, 15,9% y 24,3% de Fe2O3) y de una mezcla de ambos, sobre la capacidad de apantallar interferencias electromagnéticas de pastas de cemento Pórtland. Entre los parámetros estudiados se encuentra: el tipo de material carbonoso, la relación de aspecto del material carbonoso, el espesor del material compuesto, la frecuencia de la radiación electromagnética incidente y el porcentaje de fracción magnética en la ceniza volante. Los resultados obtenidos indican que entre los materiales carbonosos estudiados son las fibras de carbono basadas en poliacrilonitrilo con una mayor relación de aspecto las que dan mejores resultados de apantallamiento. Al aumentar el espesor del material compuesto o la frecuencia de radiación también aumenta la eficacia del apantallamiento. En lo que respecta a la ceniza volante, el incremento de la fracción magnética de la ceniza incrementa el nivel de apantallamiento. No obstante, los resultados más eficaces se obtienen por la adición conjunta de fibras de carbono y ceniza volante debido a un efecto sinérgico

Secuelas tras inyección ilegal de silicona líquida como técnica de aumento mamario: presentación de 2 casos

The use of liquid silicone for breast augmentation was widespread in the 1960s but was abandoned at the end of the decade due to numerous studies describing the development of a large number of local complications, as well as remote migration of small amounts of silicone. The use of liquid silicone also leads to enormous difficulty in the early diagnosis of breast cancer; these patients are precluded from routine screening programs and must undergo exhaustive periodic examinations. Magnetic resonance imaging has become the most effective test for the early detection of breast cancer in these patients. Indications for subcutaneous mastectomy are the presence of local complications, suspicion of a malignant lesion, or the patient’s desire to prevent both these potential problems

Pozzolanic activity of a spent fluid catalytic cracking catalyst residue

Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.The reaction between a spent fluid cracking catalyst (FC3R) residue and portlandite was monitored over 56 days using several material characterisation techniques. The results showed that the residue was heterogeneous and composed of reactive and non-reactive fractions and that both fractions contained silicon and aluminium. After 56 days, the development of C-S-H gel was evident; part of the catalyst residue was pozzolanic. The CH combination could be monitored by thermogravimetry or X-ray diffraction, by measuring the signal corresponding to CH. However, due to the low crystallinity of cementing products and their complex stoichiometry, the above-mentioned techniques were less able to characterise C-A-S-H. However, nuclear magnetic resonance techniques allowed the evolution of the pozzolanic reaction to be evaluated and the hydrate products to be characterised. Thomas Telford Ltd & 2011.Garcés, P.; Glasser, FP.; Brew, DR.; Zornoza Gómez, EM.; Paya Bernabeu, JJ. (2011). Pozzolanic activity of a spent fluid catalytic cracking catalyst residue. Advances in Cement Research. 23(3):105-111. doi:10.1680/adcr9.00036S10511123