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3. Charpy impact toughness and transition temperature in ferrite–perlite steel

Author

Cubides Herrera, C. S., Villalba Rondón, D. A., Rodríguez Baracaldo, Rodolfo, Cubides Herrera, C. S., Villalba Rondón, D. A., and Rodríguez Baracaldo, Rodolfo

Abstract

Charpy V-notch impact tests on 10 mm thick, Dual-Phase ferrite-perlite steel were evaluated at temperatures ranging from 90 ºC to -60 ºC. Fracture surfaces were analysed by optical microscope (OM). Due to the high dispersion, showed in the results, numerous tests under the same conditions and the use of statistical methods are needed to obtain a reliable value. The transition temperature calculated (45 ºC) and Charpy impact toughness was analysed in function of microstructure and carbon equivalent., Las pruebas de impacto son una importante herramienta para la obtención de importantes propiedades, como la tenacidad al impacto y la temperatura de transición ductilfragil, para la selección de un material en diseño mecánico. Se evaluó la tenacidad al impacto mediante pruebas de impacto Charpy en acero de fase doble (ferrita-perlita) de 10 mm de espesor a temperaturas que oscilan entre 90 ºC y -60 ºC. Las superficies de fractura fueron analizadas por microscopio óptico (MO). Debido a la alta dispersión, mostrada en los resultados, se emplaron numerosas pruebas en las mismas condiciones y el uso de métodos estadísticos para obtener un valor confiable. La temperatura de transición calculada (45 ºC) y la resistencia al impacto de Charpy se analizaron en función de la microestructura y el equivalente de carbono

Published
2019

4. Comportamiento de precios de las variedades de papa Parda Pastusa y Diacol Capiro en Colombia (1995-2011)

Author

Barrientos, Juan Carlos, Rondón D., Camilo, and Melo, Sandra E.

Subjects
trends, ciclos, estacionalidad, seasonality, variability, tendencias, cycles, variabilidad, time series, serie de tiempo
Abstract

El año 2013 los productores de papa de Colombia han protestado públicamente por la caída de los precios de este producto. Este fenómeno social no ha cambiado significativamente en los últimos años, pero cada año va agravándose afectando negativamente los ingresos de las familias productoras. Para hacer una aproximación explicativa se ha realizado una investigación documental sobre precios y un análisis estadístico de la serie de precios de las variedades Parda Pastusa y Diacol Capiro de los años 1995 a 2011. El análisis estadístico muestra resultados similares para ambas variedades. La tendencia de precios nominales es alcista y la de precios reales bajista. Las series presentan estacionalidad, siendo el primer semestre el de precios altos y el segundo el de precios medios y bajos. Este comportamiento estacional, sin embargo, tiene una ocurrencia de solo 65% para el periodo de estudio. La variabilidad es alta a muy alta reflejando la amplitud de rango entre los precios máximos y mínimos. Esto representa un enorme riesgo para los productores, sobre todo para los pequeños que no tienen ningún seguro financiero para su producción. Las series de precios presentan ciclos irregulares; sin embargo, es posible desarrollar un modelo matemático de predicción de precios como el que se presenta aquí, un modelo Sarima desarrollado con el software estadístico R. Este permite hacer pronósticos para algunos meses, cuyos resultados ayudarían a planificar mejor las siembras. Junto a esta estrategia, también se puede recurrir a una mejor planificación del mercadeo y la innovación tecnológica, caminos que pueden reducir la variabilidad de precios ocasionada principalmente por el clima, plagas, enfermedades, y otros. During 2013, Colombian potato growers publicly protested the drop in potato prices. This price phenomenon has not significantly changed in recent years, but every year it worsens, adversely affecting the income of farming families. In order to provide an explanation, documentary research was conducted on the prices along with a statistical analysis of the price series of the potato varieties Parda Pastusa and Diacol Capiro from 1995 to 2011. The statistical analysis showed similar results for both varieties. The nominal price had an uptrend and the real prices had a downtrend. The series showed seasonality: the first semester had a tendency for high prices and the second one had middle to low prices. However, this seasonal performance only had an occurrence of 65% for the studied period. The price variability was high to very high, reflecting the breadth of the range between the maximum and minimum prices. This presents a huge risk for producers, especially for small farmers who have no financial insurance for their production. The price series had irregular cycles; however, it was possible to develop a mathematical model to predict the prices, a Sarima model, which was developed with the statistical software R. This model allows for price forecasting for some months. These results could help better plan seeding. Alongside this strategy, producers can use best marketing planning and technological innovation, methods that can reduce the price variability caused by weather, pests, and diseases, among others.

Published
2014

5. Charpy impact toughness and transition temperature in ferrite -- perlite steel.

Author

Cubides-Herrera, C. S., Villalba-Rondón, D. A., and Rodríguez-Baracaldo, R.

Subjects
*TRANSITION temperature, *NOTCHED bar testing, *DUAL-phase steel, *FRACTURE toughness, *FERRITES, *MECHANICAL behavior of materials, *STEEL fracture
Abstract

The Charpy impact test is a significant tool for the determination of fundamental properties for materials selection in mechanical designs, like the impact toughness and the brittleductile transition temperature. Charpy V-notch impact tests on 10 mm thick, Dual-Phase ferrite-perlite steel were evaluated at temperatures ranging from 90 ºC to -60 ºC. Fracture surfaces were analysed by optical microscope (OM). Due to the high dispersion, showed in the results, numerous tests under the same conditions and the use of statistical methods are needed to obtain a reliable value. The transition temperature calculated (45 ºC) and Charpy impact toughness was analysed in function of microstructure and carbon equivalent. [ABSTRACT FROM AUTHOR]

Published
2019

9. Effects of tranexamic acid on death, vascular occlusive events, and blood transfusion in trauma patients with significant haemorrhage (CRASH-2) a randomised, placebo-controlled trial

Author

Olldashi, F., Kerçi, M., Zhurda, T., Ruçi, K., Banushi, A., Traverso, M. S., Jiménez, J., Balbi, J., Dellera, C., Svampa, S., Quintana, G., Piñero, G., Teves, J., Seppelt, I., Mountain, D., Balogh, Z., Zaman, M., Druwé, P., Rutsaert, R., Mazairac, G., Pascal, F., Yvette, Z., Chancellin, D., Okwen, P., Djokam-Liapoe, J., Jangwa, E., Mbuagbaw, L., Fointama, N., Pascal, N., Baillie, F., Jiang, J. -Y, Gao, G. -Y, Bao, Y. -H, Morales, C., Sierra, J., Naranjo, S., Correa, C., Gómez, C., Herrera, J., Caicedo, L., Rojas, A., Pastas, H., Miranda, H., Constaín, A., Perdomo, M., Muñoz, D., Duarte, Á, Vásquez, E., Ortiz, C., Ayala, B., Delgado, H., Benavides, G., Rosero, L., Mejía-Mantilla, J., Varela, A., Calle, M., Castillo, J., García, A., Ciro, J., Villa, C., Panesso, R., Flórez, L., Gallego, A., Puentes-Manosalva, F., Medina, L., Márquez, K., Romero, A. R., Hernández, R., Martínez, J., Gualteros, W., Urbina, Z., Velandia, J., Benítez, F., Trochez, A., Villarreal, A., Pabón, P., López, H., Quintero, L., Rubiano, A., Tamayo, J., Piñera, M., Navarro, Z., Rondón, D., Bujan, B., Palacios, L., Martínez, D., Hernández, Y., Fernández, Y., Casola, E., Delgado, R., Herrera, C., Arbolaéz, M., Domínguez, M., Iraola, M., Rojas, O., Enseñat, A., Pastrana, I., Rodríguez, D., La Campa, S. Á, Fortún, T., Larrea, M., Aragón, L., Madrazo, A., Svoboda, P., Izurieta, M., Daccach, A., Altamirano, M., Ortega, A., Cárdenas, B., González, L., Ochoa, M., Ortega, F., Quichimbo, F., Guiñanzaca, J., Zavala, I., Segura, S., Jerez, J., Acosta, D., Yánez, F., Camacho, R., Khamis, H., Shafei, H., Kheidr, A., Nasr, H., Mosaad, M., Rizk, S., El Sayed, H., Moati, T., Hokkam, E., Amin, M., Lowis, H., Fawzy, M., Bedir, N., Aldars, M., Rodríguez, V., Tobar, J., Alvarenga, J., Shalamberidze, B., Demuria, E., Rtveliashvili, N., Chutkerashvili, G., Dotiashvili, D., Gogichaishvili, T., Ingorokva, G., Kazaishvili, D., Melikidze, B., Iashvili, N., Tomadze, G., Chkhikvadze, M., Khurtsidze, L., Lomidze, Z., Dzagania, D., Kvachadze, N., Gotsadze, G., Kaloiani, V., Kajaia, N., Dakubo, J., Naaeder, S., Sowah, P., Yusuf, A., Ishak, A., Selasi-Sefenu, P., Sibiri, B., Sarpong-Peprah, S., Boro, T., Bopaiah, K., Shetty, K., Subbiah, R., Mulla, L., Doshi, A., Dewan, Y., Grewal, S., Tripathy, P., Mathew, J., Gupta, B., Lal, A., Choudhury, M., Gupta, S., Chug, A., Pamidimukkala, V., Jagannath, P., Maharaj, M., Vommi, R., Gudipati, N., Chhang, W. H., Patel, P., Suthar, N., Banker, D., Patel, J., Dharap, S., Kamble, R., Patkar, S., Lohiya, S., Saraf, R., Kumar, D., Parihar, S., Gupta, R., Mangual, R., Alagumuthu, Kooper, D., Mohapatra, C., David, S., Rajaleelan, W., Pangi, A., Saraf, V., Chikareddy, S., Mankar, S., Golhar, A., Sakhare, R., Wagh, N., Hazarika, D., Chaudhuri, P., Ketan, P., Purohit, G., Purohit, Y., Pandya, M., Kiran, S., Walia, S., Goyal, S., Attri, A., Sharma, R., Oberai, A., Oberai, M., Oberoi, S., Tripathi, G. K., Peettakkandy, V., Karuthillath, P., Vadakammuriyil, P., Pol, J., Pol, S., Saste, M., Raul, S., Tiwari, S., Nelly, N., Chidambaram, M., Kollengode, V., Thampan, S., Rajan, S., Raju, S., Babu, S. V., Sumathi, C., Chatterjee, P., Agarwal, A., Magar, H., Magar, M., Singh, M., Gupta, D., Haloi, K., Sagdeo, V., Giri, P., Verma, N., Jariwala, R., Goti, A., Prabhu-Gaonkar, A., Utagi, S., Joshi, M., Agrawal, R., Sharma, G., Saini, G., Tewari, V., Yadav, Y., Parihar, V., Venkataramana, N., Rao, S., Reddy, N., Chander, S. G., Hathila, V., Das, V., Agaja, K., Purohit, A., Lahari, A., Bhagchandani, R., Vidyasagar, B., Sachan, P. K., Das, T., Vyas, S., Bhattacharjee, S., Sancheti, P., Manoj, T., Moideen, M., Pansey, K., Chandrasekaran, V. P., Saikia, K., Tata, H., Vhora, S., Shah, A., Rangad, G., Rajasekaran, S., Shankarlal, S. T., Devadoss, S., Saleem, M., Pillay, H., Hazarika, Z., Deshmukh, P., Murugappan, S. P., Jaiswal, A., Vangani, D., Modha, P., Chonzik, C., Praveen, M., Sethurayar, V., Ipe, S., Shetty, N., Gupta, R. P., Jain, V., Shah, K., Dwikoryanto, M., Golden, N., Atmadjaya, K., Wiargitha, K., Sudiasa, K., Suwedagatha, G., Bal Afif, F., Budipramana, V., Tabrani, Lemuel, A., Chandra, S., Ama, F., Sherafatkazemzadeh, E., Moradi, E., Sheikhi, A., Ziaee, A., Fanaei, A., Hajinasrollah, E., Amini, A., Mohammad, B., Hadi, N., Perone, G., Peri, E., Volpi, A., Johnson, J., Abe, M., Mutiso, V., Okanga, B., Ojuka, D., Abdullah, B., Rahman, H., Noh, Y., Jamaluddin, S., Dawal, H., Roslani, A., Law, C. -W, Devashanti, P., Wahab, Y., Velaiutham, S., Dato, R., Loría, J., Montes, E., Gómez, E., Cazales, V., Bautista, P., Bautista, R., Ahumada, D., Hernández, E., Velásquez, G., Ortega, P., Lira, G., Estrada, F., Casasola, J., Olaomi, O., Abubakar, Y., Apollo, K., Badejo, O., Ihekire, O., Iribhogbe, P., Oludiran, O., Obeta, E., Okojie, C., Udefiagbon, E., Komolafe, E., Olaleye, P., Uzochukwu, T., Onakpoya, U., Dongo, A., Uhunmwagho, O., Eighemerio, E., Morgan, E., Thanni, L., Afolabi, A., Akinola, T., Ademola, A., Akute, O., Khalid, L., Abubakar, L., Aminu, M., Ogirima, M., Attansey, A., Michael, D., Aremu, O., Olugbenga, O., Ukpong, U., Salman, Y., Obianyo, N., Ani, C., Ezeadawi, R., Kehinde, O., Olaide, A., Jogo, A., Bitto, T., Anyanwu, S., Mbonu, O., Oludara, M., Somoye, M., Shehu, B., Ismail, N., Katchy, A., Ndoma-Egba, R., Grace-Inah, N., Songden, Z., Abdulraheem, A., Otu, A., Nottidge, T., Inyang, D., Idiapho, D., Giebel, H., Hassan, R., Adisa, A., Akinkuolie, A., Okam, K., Musa, A., Falope, I., Eze, J., Caballero, J., Azabache, W., Salirrosas, O., Soto, A., Torres, E., Ramírez, G., Malca, C., Velez, J., Yepez, R., Yupanqui, H., Lagos, P., Rodriguez, D., Flores, J., Moya, A., Barrionuevo, A., Gonzales-Portillo, M., Nunez, E., Eldawlatly, A., Al Naami, M., Delvi, B., Khalid, K., Alyafi, W., Djurovic, B., Ng, I., Yaghi, A., Laincz, A., Trenkler, S., Valky, J., Modiba, M., Legodi, P., Rangaka, T., Wallis, L., Muñoz, Á, Serrano, A., Misis, M., Rubi, M., La Torre, V., Ellawala, R., Wijeratna, S., Gunaratna, L., Wijayanayaka, C., Nungu, K., Billy Haonga, Mtapa, G., Yutthakasemsunt, S., Kittiwattanagul, W., Piyavechvirat, P., Impool, T., Thummaraj, S., Salaeh, R., Tangchitvittaya, S., Wattanakrai, K., Soonthornthum, C., Jiravongbunrod, T., Meephant, S., Subsompon, P., Pensuwan, P., Chamnongwit, W., Jerbi, Z., Cherif, A., Nash, M., Harris, T., Banerjee, J., Freij, R., Kendall, J., Moore, S., Townend, W., Cottingham, R., Becker, D., Lloyd, S., Burdett-Smith, P., Mirza, K., Webster, A., Brady, S., Grocutt, A., Thurston, J., Lecky, F., Goodacre, S., Mulla, Y., Sakala, D., and Chengo, C.

10. Effect of CO 2 Flow Rate on the Extraction of Astaxanthin and Fatty Acids from Haematococcus pluvialis Using Supercritical Fluid Technology.

Author

Espinosa Álvarez C, Vardanega R, Salinas-Fuentes F, Palma Ramírez J, Bugueño Muñoz W, Jiménez-Rondón D, Meireles MAA, Cerezal Mezquita P, and Ruiz-Domínguez MC

Subjects
Technology methods, Xanthophylls chemistry, Carbon Dioxide chemistry, Chlorophyceae chemistry, Chromatography, Supercritical Fluid methods, Fatty Acids chemistry, Microalgae chemistry
Abstract

Haematococcus pluvialis is the largest producer of natural astaxanthin in the world. Astaxanthin is a bioactive compound used in food, feed, nutraceutics, and cosmetics. In this study, astaxanthin extraction from H. pluvialis by supercritical fluid extraction was evaluated. The effects of temperature (40 and 50 °C), pressure (40 and 50 MPa), and CO 2 flow rate (2 and 4 L/min) were investigated. The results showed that the highest astaxanthin recovery was obtained at 50 °C/50 MPa and the CO 2 flow rates evaluated had no significant effect. It was possible to achieve astaxanthin recoveries of 95% after 175 min for a CO 2 flow rate of 2 L/min, and 95 min for CO 2 flow rate of 4 L/min. The ω-6/ω-3 ratios obtained were similar in all conditions, reaching 0.87, demonstrating that the extracts from H. pluvialis by SFE are rich in unsaturated fatty acids (UFA) which increases their positive effects when used as a functional ingredient in food.

Published
2020
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11. Bacteria-Carried Iron Oxide Nanoparticles for Treatment of Anemia.

Author

Garcés V, Rodríguez-Nogales A, González A, Gálvez N, Rodríguez-Cabezas ME, García-Martin ML, Gutiérrez L, Rondón D, Olivares M, Gálvez J, and Dominguez-Vera JM

Subjects
Anemia blood, Anemia metabolism, Animals, Enterocytes metabolism, Ferric Compounds administration & dosage, Ferric Compounds pharmacokinetics, HT29 Cells, Hemoglobins analysis, Hepcidins analysis, Humans, Iron blood, Male, Nanoparticles administration & dosage, Nanoparticles analysis, Probiotics administration & dosage, Probiotics pharmacokinetics, Rats, Wistar, Tissue Distribution, Anemia therapy, Ferric Compounds therapeutic use, Lactobacillus metabolism, Nanoparticles therapeutic use, Probiotics therapeutic use
Abstract

The efficiency of maghemite nanoparticles for the treatment of anemia was sensibly higher when nanoparticles were incorporated onto the probiotic bacterium Lactobacillus fermentum (MNP-bacteria) than when administrated as uncoated nanoparticles (MNP). Plasma iron and hemoglobin, intestine expression of divalent metal transporter 1 (DMT1) and duodenal Cytochrome b (DcytB), as well as hepatic expression of the hormone hepcidin were fully restored to healthy levels after administration of MNP-bacteria but not of MNP. A magnetic study on biodistribution and biodegradation showed accumulation of maghemite nanoparticles in intestine lumen when MNP-bacteria were administrated. In contrast, MNP barely reached intestine. In vivo MRI studies suggested the internalization of MNP-bacteria into enterocytes, which did not occur with MNP. Transmission electronic microscopy confirmed this internalization. The collective analysis of results point out that L. fermentum is an excellent carrier to overcome the stomach medium and drive maghemite nanoparticles to intestine, where iron absorption occurs. Due the probiotic ability to adhere to the gut wall, MNP-bacteria internalize into the enterocyte, where maghemite nanoparticles are delivered, providing an adequate iron level into enterocyte. This paper advances a new route for effective iron absorption in the treatment of anemia.

Published
2018
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12. Magnetic study on biodistribution and biodegradation of oral magnetic nanostructures in the rat gastrointestinal tract.

Author

Martín M, Rodríguez-Nogales A, Garcés V, Gálvez N, Gutiérrez L, Gálvez J, Rondón D, Olivares M, and Dominguez-Vera JM

Subjects
Animals, Bacteria, Magnetics, Male, Probiotics, Rats, Rats, Wistar, Tissue Distribution, Gastrointestinal Tract metabolism, Iron analysis, Magnetite Nanoparticles analysis
Abstract

We have undertaken a magnetic study on the oral biodistribution and biodegradation of nude maghemite nanoparticles of 10 nm average size (MNP) and probiotic bacteria, Lactobacillus fermentum, containing thousands of these same nanoparticles (MNP-bacteria). Using AC magnetic susceptibility measurements of the stomach, small intestine, cecum and large intestine obtained after rat sacrifice, and iron content determination by ICP-OES, we have monitored the biodistribution and biodegradation of the maghemite nanoparticles along the gastrointestinal tract, after oral administration of both MNP and MNP-bacteria. The results revealed that the amount of magnetic nanoparticles accumulated in intestines is sensibly higher when MNP-bacteria were administered, in comparison with MNP. This confirms our initial hypothesis that the use of probiotic bacteria is a suitable strategy to assist the magnetic nanoparticles to overcome the stomach medium, and to achieve their accumulation in intestines. This finding opens doors to different applications. Since iron absorption in humans takes place precisely in the intestines, the use of MNP-bacteria as an iron supplement is a definite possibility. We have actually illustrated how the administration of MNP-bacteria to iron-deficient rats corrects the iron levels after two weeks of treatment.

Published
2016
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