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Search Results: 1 - 10 of 8464 matches for " Nathalie Romero "
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ImaginARTE
Nathalie Páez Nascimento,Florencia Alfici,Oscar Romero Orellano
Revista Argentina de Radiología , 2013,
Abstract:
Electrochemical behavior study of AISI 304 and 316 in carbonate or chloride contaminated concrete
Millano,Valentina; Sánchez,Miguel; Rincón,Oladis T; Linares,Douglas; Romero,Nathalie;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2006,
Abstract: in this work the behavior of steel aisi-sae 304 and 316 were studied in reinforced concrete, using prisms exposed in environments with chlorides, with chlorides incorporated or exposed with high contents of co2. all of them with a a/c relation of 0.65, compressive strength of 150 kgf/cm2 and they were at environments of 30 ± 5°c and 90% hr. at the same time, several electrodes of stainless steel aisi 304 were studied immersing them in pore water solution to different times and chloride ion concentrations from 1 and 2% p/p. the techniques of measurement used were: potential, linear polarization and electrochemical impedance spectroscopy (eis). stainless steel 304 and 316 reported average corrosion rates below 0.02 μa/cm2, for all the conditions evaluated in the reinforced concrete prism. nevertheless, when comparing the values of corrosion rate obtained through eis with those from linear polarization for the reinforcements that presented greater corrosion rates (30.1 μa/cm2), these were similar when the nyquist diagram showed capacitive oxide film. on the contrary, when the corrosion rate were very low (<0.01 μa/cm2), the mathematical adjustment found limitation for the systems with high resistance polarization. the corrosion rates reported for aisi-sae 304 in the pore water tests were greater (0.05 and 0.12 μa/cm2/1% nacl; 0.24 and 0.05 μa/cm2/2% nacl), after 6 and 336 hours, respectively; which indicates that the corrosion rate is increased with time of exposure for 1% of nacl, not thus for 2%.
The atmospheric corrosivity maps in Zulia region
Rincón,álvaro; Rincón,Oladis T; Rodríguez,Raquel; Romero,Nathalie; Rincón,Ana Ismenia;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2004,
Abstract: in this research a one-year study was run, for two different periods, in eight test stations of the zulian region, in which the corrosion rate of steel sae1010 and 99% copper were evaluated by weight loss. samples of 10×15cm were exposed to the prevailing wind direction in the natural environments, on racks with 45o inclination. deposition rates of chloride ions, sulfur dioxide, atmospheric dust, and the meteorological variables with greater incidence were determined. the planetario was the most aggressive station for the steel, with 26.10 μm/year, and the t. bachaquero test site for copper with 8.96 μm/year. in the repetition study for the first year of exposure, a comparative decrease from c5 to c4 was found, which was due to the faster formation of the protector patina as a result of the increment in contaminants deposition. later, the zulian maps of atmospheric corrosion for steel and copper were constructed, using pies to report the results, where the diameter of the pie represents the corrosion rate of the material in each zone and the size of the pie portions represent the effect of each variable in the atmospheric corrosion process.
Evaluación de sistemas de recubrimientos duplex en ambientes marinos tropicales Evaluation of duplex coating’s system in tropical marine environments
Nathalie Romero,Oladis de Rincón,Miguel Sánchez,álvaro Rincón
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: En este trabajo se seleccionaron nueve esquemas de diferentes empresas del mercado nacional, de reconocida trayectoria, para realizar la evaluación en ambientes muy severos, marinos tropicales. A tal efecto se utilizaron perfiles de acero galvanizado nuevo y ya expuesto (con corrosión del sustrato), a las mismas condiciones de evaluación. Se seleccionaron dos estaciones de campo: La Voz y El Cruce del Lago de Maracaibo, ambos climas marinos tropicales de elevada agresividad. Adicionalmente, se efectuaron ensayos acelerados en una estación en el Centro de Estudios de Corrosión (CEC), utilizando la norma ISO 11474, y en el laboratorio (Cámara climática/PROHESION). Cabe destacar que luego de mas de 36 meses de exposición en las estaciones de campo, el desempe o de los diferentes esquemas sobre galvanizado ya expuesto se observa claramente definido, pudiendo seleccionar fácilmente el que muestra un mejor comportamiento. No obstante, para el caso del galvanizado nuevo, luego de este tiempo de evaluación, no se aprecia tan evidente la diferencia en el comportamiento; ya que esquemas de recubrimiento con un pobre desempe o en el galvanizado expuesto presentan un buen comportamiento en ese sustrato, demostrando la eficiencia de los sistemas Duplex. In this work nine different coating systems, from national suppliers, were selected to perform the evaluation in two severe tropical marine environments. New galvanized profiles as well as pre-exposed to the same environmental conditions were used as the test probes. Two different field stations were selected: La Voz and The Cross of Maracaibo Lake. Additionally, accelerated test were carried out in a station located at Centro de Estudios de Corrosión (CEC) by using the standard ISO 11474, and in the laboratory (PROHESION chamber). It is important to emphasize that after more than 36 month-exposure the behavior of the different coating systems on pre-exposed galvanized was clear, permitting to select the coating system with the best performance. Nevertheless in the case of new galvanized probes, after the evaluation period, most of the duplex systems had a very good performance.
Six-Year Evaluation of Thermal-Sprayed Coating of Zn/Al in Tropical Marine Environments
Orlando Salas,Oladis Troconis de Rincón,Daniela Rojas,Adriana Tosaya,Nathalie Romero,Miguel Sánchez,William Campos
International Journal of Corrosion , 2012, DOI: 10.1155/2012/318279
Abstract: The main objective of this research was to evaluate the performance of thermal-sprayed coating of Zn/Al (double layer) after six years of exposure, with and without the use of sealant (wash primer) in tropical marine environments of very high aggressiveness: La Voz Station (located at the Peninsula de Paraguaná/Falcón State) and Lake Maracaibo Crossing Station (located at Zulia State), in Venezuela. To that effect, carbon steel coupons (100?mm × 150?mm × 2?mm) were sprayed by flame process. The coupons were characterized by means of initial weight, thickness, metallographic, adherence, and roughness, being evaluated monthly by visual inspection during six years. After removal, the coupons were evaluated by microscopic analysis to determine the morphology of attack, microstructure, penetration of contaminants, composition, and morphology of corrosion products. The results showed that after six years, the double-layer system represents an excellent choice for corrosion protection of steel by combining the galvanic protection of zinc with the erosion resistance of aluminum. However, due to the erosion-corrosion effect, a sealant such as wash primer can be used in order to extend its service life. 1. Introduction Worldwide, many organizations have made numerous efforts in terms of studies and research looking for new coating systems to improve the durability of structures exposed to marine and coastal marine environments, providing protection to the steel during its service life and producing a minimal impact on the environment. In marine and coastal marine environments, where a number of factors are present such as high-chloride concentrations, strong winds, changing conditions of relative humidity and temperature (especially in tropical climates like Venezuela), organic coatings do not perform properly. In this regard, thermal-sprayed coatings appear as an alternative to protect steel structures in those environments. In the United States, Europe, and Japan [1, 2], these coatings are gaining importance for their promising low environmental impact, corrosion resistance, cost benefits, durability, and other advantages over other conventional paint systems. In 1974, the American Welding Society [3] performed a study that was considered a pioneer in thermal sprayed coating where it reported that these coatings with Zn and Al, with and without sealer, exposed in marine and industrial environments, provided protection against corrosion for 19 years. Moreover, in 1987, the Laque Center for Corrosion Technology, INC. [4] reported that the degree of protection of
Evaluation of duplex coating?s system in tropical marine environments
Romero,Nathalie; de Rincón,Oladis; Sánchez,Miguel; Rincón,álvaro; Millano,Valentina; Linares,Douglas; Salas,Orlando; Serrano,Mirla;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: in this work nine different coating systems, from national suppliers, were selected to perform the evaluation in two severe tropical marine environments. new galvanized profiles as well as pre-exposed to the same environmental conditions were used as the test probes. two different field stations were selected: la voz and the cross of maracaibo lake. additionally, accelerated test were carried out in a station located at centro de estudios de corrosión (cec) by using the standard iso 11474, and in the laboratory (prohesion chamber). it is important to emphasize that after more than 36 month-exposure the behavior of the different coating systems on pre-exposed galvanized was clear, permitting to select the coating system with the best performance. nevertheless in the case of new galvanized probes, after the evaluation period, most of the duplex systems had a very good performance.
Importancia de la referencia médica en el diagnóstico de parasitosis intestinales por métodos coproparasitológicos
Chacón Fonseca,Nathalie de Jesús; Contreras,Rosa; Márquez,Wilfredo; Salinas,Raquel Sarahí; Romero,Johanna María;
Revista de la Facultad de Medicina , 2007,
Abstract: soil transmitted helminthes laboratory of the tropical medicine institute studies feces by simple method, formol-triton-eter and baermann. other coproparasitologic techniques like: graham, kinyoun and kato-katz are process if they are asked by physicians. the objectives of the current study were: evaluate the reference quality of the medical record, the impact in the final diagnosis applying coproparasitologic techniques and the occurrence of parasitic intestinal disease. each reference was evaluated between 0 and 12 points, depending on the presence of quality parameters. for a total of 392 reference: 170 patients from public hospital, 157 from tropical medicine institute, 38 from private hospital and 27 without information, the mean reference evaluation was 4 points. the poor quality of the reference did not permit to measure the impact in the final parasitologic diagnosis. the most frequent parasites were blastocystis hominis (8,9 %), entamoeba coli (3,5 %), ascaris lumbricoides and giardia intestinalis (both with 2,54 %). for the total hiv positive (10/173), only for 5, kinyoun technique was solicited by the reference, cryptosporidium sp. was positive for one. two patients were referred because of pruritus ani and indication of graham, both were negative for enterobius vermicularis. four patients referred with suspect of schistosomiasis without a kato-katz indication by the doctor. a complete reference of the medical record contributes to the application of the first choice of coproparasitologic techniques, to favor real diagnosis towards the benefit of the patients. we structured a new model of reference of the medical record to initiate an education labor of the health personal about the coproparasitologic techniques.
Adjuvant Treatment for High-Risk Operable Prostate Cancer  [PDF]
Bernard Paule, Nathalie Brion
Journal of Cancer Therapy (JCT) , 2010, DOI: 10.4236/jct.2010.11002
Abstract: Patients who have undergone a radical prostatectomy may have to face high risks of recurrence. The risk of recurrence is elevated due to probable occult metastatic disease at the time of diagnosis. A rationale for using multimodal approach in order to minimize the chance of disease recurrence and to improve the survival of high risk patients is emerging from preclinical and clinical studies. New molecular and genetics assays, may help to select patients most likely to benefit from these approaches. In this review, we will especially discuss the potential benefits of adjuvant therapy after radical prostatectomy. This paper presents the identification of these high-risk patients; the explanation of an adjuvant treatment of residual disease after a radical prostatectomy; the clinical studies with adjuvant androgen deprivation, radiotherapy and/or chemotherapy and the microarrays analysis. This review highlights the importance of these new adjuvant treatments that aims at targeting the factor which triggers metastatic disease following a radical prostatectomy
Therapeutic MUC1-Based Cancer Vaccine Expressed in Flagella-Efficacy in an Aggressive Model of Breast Cancer  [PDF]
Nathalie Machluf, Ruth Arnon
World Journal of Vaccines (WJV) , 2012, DOI: 10.4236/wjv.2012.23015
Abstract: MUC1, a tumor-associated antigen overexpressed in many carcinomas, represents a candidate of choice for cancer immunotherapy. Flagella-based MUC1 vaccines were tested in therapeutic setting in two aggressive breast cancer models, comprising the implantation of the 4T1-MUC1 cell line in either Balb/c, or Human MUC1 transgenic mice in which spontaneous metastases occurs. Recombinant flagella carrying only 7 amino acid of MUC1 elicited therapeutic activity, affecting both the growth of established growing tumors and the number of metastases. Higher therapeutic activity was achieved with an additional recombinant flagella designed with the SYFPEITHI algorithm. The vaccines triggered a Th1 response against MUC1 with no evident autoimmune response towards healthy MUC1-expressing tissues. Recombinant flagella carrying a 25-residue fragment of MUC1, induced the most effective response, as evidenced by a significant reduction of both the size and growth rate of the tumor as well as by the lower number of metastases, and expanding life span of vaccinated mice.
Lab-Scale Performance Evaluation of Vertical Flow Reed Beds for the Treatment of Chlorobenzene Contaminated Groundwater  [PDF]
Gerard Merlin, Nathalie Cottin
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.328099
Abstract: Chlorinated Benzenes (CBs) that were released into the environment contaminate groundwater at many existing and former industrial sites. A research program was initiated to investigate the ecoremediation of CBs contaminated groundwater using subsurface flow constructed wetlands. Four lab-scale experiments were performed to evaluate re- moval efficiency with different operation conditions. The first experiment was achieved with two different solid-state materials: a peat and a lava stone (pozzolana). In order to stimulate biological activity, organic matter coming from an aged Vertical Flow Constructed Wetlands (VFCW) was added to the media. Mass balance was determined to assess the fate of these pollutants in this system. The biofiltres of the second experiment were constructed with the same materials but bioaugmentation was realized by adding organic matter of VFCW or by bacteria inoculums. Peat and pozzolana biofiltres planted with Phragmites australis constituted the third experiment to evaluate the effect of plants. Bioaugmen- tation was constituted by the addition of OM coming from aged VFCW. Compost mixed with pozzolana was the solid-state material of the fourth experiment. Columns were made of two stages. The first stage was unplanted and the second stage was planted with Phragmites. Peat has been replaced by compost, a renewable material. Lab-scale biofil- tres remove CBs with an efficiency of 70% - 99%, depending on studied media and conditions. Greater efficiency was observed with bioaugmented media. Volatilization was very low (<0.2%) and the detection of chlorides in water indi- cated the occurrence of biodegradation. The experiments have shown that organic solid-state materials (compost or peat) are useful for groundwater remediation, with higher treatment efficiency than pozzolana material. Bioaugmentation increased biological activity. Clogging of biofiltres have been observed and can be reduced by the presence of plants or by a resting period of 14 - 21 days (requiring alternative feedings on several filters).
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