Analysis of β-tricalcium phosphate granules prepared with different formulations by nano-computed tomography and scanning electron microscopy

International audience

The use of animal models in multiple myeloma

International audience

Estudio de la acumulación, transferencia y especiación de arsénico en cultivos de maíz y su riesgo potencial para la salud humana

Con el objetivo de evaluar la transferencia de arsénico (As) del campo agrícola hacia la planta de maíz y el ser humano, en este trabajo fueron estudiados: 1) los parámetros fisicoquímicos del suelo sobre la acumulación y translocación de As en el cultivo, 2) la distribución de las especies de As en el agua, suelo y planta, 3) la fitodisponibilidad de As en el suelo agrícola, y 4) la bioaccesibilidad de As en el grano para el ser humano. Para tal propósito, se caracterizaron fisicoquímicamente el agua, el suelo y el cultivo de maíz de tres zonas agrícolas de San Luis Potosí (denominadas A, B y C) y se determinó el contenido de As mediante espectrometría de fluorescencia atómica acoplado a un sistema de generación de hidruros (HG-AFS). Los datos experimentales fueron analizados mediante análisis de conglomerados (cluster) y de componentes principales. La implementación de la metodología de extracción de especies de As en las partes del cultivo de maíz fue evaluada mediante estudios de recuperación. Las metodologías desarrolladas para la determinación de As biodisponible en el suelo agrícola y de As bioaccesible en el grano fueron automatizadas mediante el sistema de análisis por inyección en flujo multijeringa utilizando HG-AFS como detector y optimizadas mediante un diseño Doehlert. Contribuciones y Conclusiones: En general, la concentración de As total en el cultivo de maíz fue en el orden: raíz >> tallo y hoja > grano. El As(V) fue la forma predominante en los lixiviados de suelo y presentó una correlación estadísticamente significativa (p < 0.05) con el As total en raíz, tallo y hoja de maíz.

Desenvolvimento de tubulação em compósito polimérico revestida externamente com poliuretano de alta densidade

Pipelines for the transport of crude oil from the production wells to the collecting stations are named production lines . These pipes are subjected to chemical and electrochemical corrosion according to the environment and the type of petroleum transported. Some of these lines, depending upon the composition of the fluid produced, may leak within less than one year of operation due to internal corrosion. This work aims at the development of composite pipes with an external protecting layer of high density polyurethane for use in production lines of onshore oil wells, meeting operational requirements. The pipes were manufactured using glass fibers, epoxy resin, polyester resin, quartz sand and high density polyurethane. The pipes were produced by filament winding with the deposition of high density polyurethane on the external surface and threaded ends (API 15 HR/PM-VII). Three types of pipes were manufactured: glass/epoxy, glass/epoxy with an external polyurethane layer and glass/epoxy with an intermediate layer of glass fiber, polyester, sand and with an external polyurethane layer. The three samples were characterized by Scanning Electronic Microscopy (SEM) and for the determination of constituent content. In addition, the following tests were conducted: hydrostatic test, instant rupture, shorttime failure pressure, Gardner impact, transverse stiffness and axial tension. Field tests were conducted in Mossoró RN (BRAZIL), where 1,677 meters of piping were used. The tests results of the three types of pipes were compared in two events: after two months from manufacturing of the samples and after nine months of field application. The results indicate that the glass/epoxy pipes with an intermediate layer of fiber glass composite, polyester e sand and with an external layer of high density polyurethane showed superior properties as compared to the other two and met the requirements of pressure class, axial tensile strength, transverse stiffness, impact and environmental conditions, for onshore applications as production lines

Estudos de Durabilidade Frente ao Ataque Ácido de Compósitos Portland-Polímero para Cimentação de Poços de Petróleo

Portland-polymers composites are promising candidates to be used as cementing material in Northeastern oil wells of Brazil containing heavy oils submitted to steam injection. In this way, it is necessary to evaluate its degradation in the commonly acidizind agents. In addition, to identify how aggressive are the different hostile environments it is an important contribution on the decision of the acidic systems to be used in. It was investigated the performance of the Portland-polymer composites using powdered polyurethane, aqueous polyurethane, rubber tire residues and a biopolymer, those were reinforced with polished carbon steel SAE 1045 to make the electrochemical measurements. HCl 15,0 %, HCl 6,0 % + HF 1,5 % (soft mud acid), HCl 12,0 % + HF 3,0 % (regular mud acid) and HAc 10 % + HF 1,5 % were used as degrading environment and electrolytes. The more aggressive acid solution to the plain Portland hardened cement paste was the regular mud acid, that showed loss of weight around 23.0 %, followed by the soft mud acid, the showed 11.0 %, 15.0 % HCl with 7,0 % and, at last the 10.0 % HAc plus HF 1.5 % with just 1.0 %. The powdered polyurethane-composite and the aqueous polyurethane one showed larger durability, with reduction around 87.0 % on the loss of weight in regular mud acid. The acid attack is superficial and it occurs as an action layer, where the degraded layer is responsible for the decrease on the kinetic of the degrading process. This behavior can be seen mainly on the Portland- aqueous polyurethane composite, because the degraded layer is impregnated with chemically modified polymer. The fact of the acid attack does not have influence on the compressive strength or fratography of the samples, in a general way, confirms that theory. The mechanism of the efficiency of the Portland-polymers composites subjected to acid attack is due to decreased porosity and permeability related with the plain Portland paste, minor quantity of Ca+2, element preferentially leached to the acidic solution, wave effect and to substitute part of the degrading bulk for the polymeric one. The electrolyte HAc 10 % + HF 1,5 % was the least aggressive one to the external corrosion of the casing, showing open circuit potentials around +250 mV compared to -130 mV to the simulated pore solution to the first 24 hours immersion. This behavior has been performed for two months at least. Similar corrosion rates were showed between both of the electrolytes, around 0.01 μA.cm-2. Total impedance values, insipient arcs and big polarization resistance capacitive arcs on the Nyquist plots, indicating passivity process, confirm its efficiency. In this way, Portlandpolymers composites are possible solutions to be succeed applied to oilwell cementing concomitant submitted to steam injection and acidizing operation and the HAc 10,0 % + HF 1,5 % is the less aggressive solution to the external corrosion of the casing

Exploring the future of immersive education

Trabalho apresentado em iLRN 2016 - Workshop, Short Paper and Poster Proceedings from the Second Immersive Learning Research Network Conference, Santa Barbara, California, USA, 2016.

Effect of different feed-rate in bone drilling: experimental and numerical study

The behaviour of bone tissue during drilling has been subject of recent studies due to its great importance. Because of thermal nature of the bone drilling, high temperatures and thermal mechanical stresses are developed during drilling that affect the process quality. However, there is still a lack information with regard to the distribution of mechanical and thermal stresses during bone drilling. The present paper describes a sequentially coupled thermal-stress analysis to assess the mechanical and thermal stress distribution during bone drilling. A three-dimensional thermo-mechanical model was developed using the ANSYS/LSDYNA finite element code under different drilling conditions. The model incorporates the dynamic characteristics of drilling process, as well as the thermo-mechanical properties of the involved materials. Experimental tests with polyurethane foam materials were also carried out. It was concluded that the use of higher feed-rates lead to a decrease of normal stresses and strains in the foam materials. The experimental and numerical results were compared and showed good agreement. The proposed numerical model could be used to predict the better drilling parameters and minimize the bone injuries.

Simulador radiográfico antropomórfico de mama humana

Mammography is a diagnostic imaging method in which interpretation depends on knowledge of radiological aspects as well as the clinical exam and pathophysiology of breast diseases. In this work a mammography phantom was developed to be used for training in the operation of mammographic x-ray equipment, image quality evaluation, self-examination and clinical examination of palpation. Polyurethane was used for the production of the phantoms for its physical and chemical properties and because it is one of the components normally used in prostheses. According to the range of flexibility of the polyurethane, it was possible to simulate breasts with higher or lower amount of adipose tissue. Pathologies such as areolar necrosis and tissue rejection due to surgery reconstruction after partial mastectomy were also simulated. Calcifications and nodules were simulated using the following materials: polyethylene, poly (methyl methacrylate), polyamide, polyurethane and poly (dimethyl silicone). Among these, polyethylene was able to simulate characteristics of calcification as well as breast nodules. The results from mammographic techniques used in this paper for the evaluation of the phantoms are in agreement with data found in the literature. The image analyses of four phantoms indicated significant similarities with the human skin texture and the female breast parenchyma. It was possible to detect in the radiographic images produced regions of high and low radiographic optical density, which are characteristic of breasts with regions of different amount of adipose tissue. The stiffnesses of breast phantoms were adjusted according to the formulation of the polyurethane which enabled the production of phantoms with distinct radiographic features and texture similar to human female breast parenchyma. Clinical palpation exam of the phantoms developed in this work indicated characteristics similar to human breast in skin texture, areolar region and parenchyma

Color stability and surface roughness of artificial teeth brushed with an experimental Ricinus communis toothpaste

Aim: To evaluate, in vitro, the effect of brushing with a Ricinus communis -based experimental toothpaste on color stability and surface roughness of artificial teeth. Methods: Ninety artificial teeth (maxillary central incisors) in different shades, light and dark (NatusDent Triple Pressing, Dentbras) were used. Initial color (Spectrophotometer Easyshade, VITA) and surface roughness (Rugosimeter Surfcorder SE 1700, Kosakalab) readouts were performed. After baseline measurements, samples were assigned to 10 groups (n=9) according to the artificial tooth shade and type of toothpaste used during the mechanical brushing test (Pepsodent, MAVTEC): Sorriso Dentes Brancos – SDB, Colgate Luminous White - CLW (Colgate-Palmolive), Close up White Now - CWN (Unilever), Trihydral - THL (Perland Pharmacos) and Ricinus communis - RCE (Experimental). After 29,200 cycles of brushing, corresponding to 2 years of brushing by a healthy individual, new color and roughness readouts of the specimens were performed. Data (before and after the tests) were statistically analyzed (2-way repeated measures ANOVA, Tukey, p<0.05). Results: RCE toothpaste produced the greatest color stability for dark tooth shade and the second best color stability for light tooth shade. For surface roughness alteration, there was no difference (p>0.05) for any tested toothpaste regardless of tooth shade. Conclusions: The experimental Ricinus communis toothpaste did not cause color and surface roughness alteration in the artificial teeth, and it may be considered a suitable option for denture cleaning.

Pastas compósitas cimento/sílica/polímero para cimentação de poços de baixa profundidade sujeitas à injeção de vapor

The production of heavy oil fields, typical in the Northeastern region, is commonly stimulated by steam injection. High bottom hole temperatures are responsible not only for the development of deleterious stresses of the cement sheath but also for cement strength retrogression. To overcome this unfavorable scenario, polymeric admixtures can be added to cement slurries to improve its fracture energy and silica flour to prevent strength retrogression. Therefore, the objective of the present study was to investigate the effect of the addition of different concentrations of polyurethane (5-25%) to cement slurries containing 40% BWOC silica flour. The resulting slurries were characterized using standard API (American Petroleum Institute) laboratory tests. In addition to them, the mechanical properties of the slurries, including elastic modulus and microhardness were also evaluated. The results revealed that density, free water and stability of the composite cement/silica/polyurethane slurries were within acceptable limits. The rheological behavior of the slurries, including plastic viscosity, yield strength and gel strength increased with the addition of 10% BWOC polyurethane. The presence of polyurethane reduced the fluid loss of the slurries as well as their elastic modulus. Composite slurries also depicted longer setting times due to the presence of the polymer. As expected, both the mechanical strength and microhardness of the slurries decreased with the addition of polyurethane. However, at high bottom hole temperatures, the strength of the slurries containing silica and polyurethane was far superior than that of plain cement slurries. In summary, the use of polyurethane combined with silica is an interesting solution to better adequate the mechanical behavior of cement slurries to heavy oil fields subjected to steam injection

Síntese e caracterização de nanocompósitos magnéticos empregando polimerização radicalar em meios homogêneo (blk) e heterogêneo (miniemulsão)

Tese (doutorado)—Universidade de Brasília, Instituto de Química, Curso de Pós-Graduação em Química, 2016.

Obtenção de álcool alílico (PROP-2-EN-1-OL) a partir da glicerina derivada do biodiesel de óleo de mamona

In this work, biodiesel was produced from castor oil that was a byproduct glycerin. The molar ratio between oil and alcohol, as well as the use of (KOH) catalyst to provide the chemical reaction is based on literature. The best results were obtained using 1 mol of castor oil (260g) to 3 moles of methyl alcohol (138g), using 1.0% KOH as catalyst at a temperature of 260 ° C and shaken at 120 rpm. The oil used was commercially available, the process involves the reaction of transesterification of a vegetable oil with methyl alcohol. The product of this reaction is an ester, biodiesel being the main product and the glycerin by-product which has undergone treatment for use as raw material for the production of allyl alcohol. The great advantage of the use of glycerin to obtain allyl alcohol is that its use eliminates the large amount of waste of the biodiesel and various forms of insult to the environment. The reactions for the formation of allyl alcohol was conducted from formic acid and glycerin in a ratio 1/1, at a temperature of 260oC in a heater blanket, being sprayed by a spiral condenser for a period of 2 hours and the product obtained contains mostly the allylic alcohol .. The monitoring of reactions was performed by UV-Visible Spectrophotometer: FTIR Fourier transform, the analysis showed that these changes occur spectrometer indicating the formation of the product allylic alcohol (prop-2-en-1-ol) in the presence of water, This alcohol was appointed Alcohol GL. The absorption bands confirms that the reaction was observed in (υ C = C) 1470 -1600 cm -1 and (υ CO), 3610-3670 attributed to C = C groups and OH respectively. The thermal analysis was carried out in a thermogravimetric analyzer SDT Q600, where the mass and temperature are displayed against time, that allows checking the approximate rate of heating. The innovative methodology developed in the laboratory (LABTAM, UFRN), was able to treat the glycerine produced by transesterification of castor oil and used as raw material for production of allyl alcohol, with a yield of 80%, of alcohol, the same is of great importance in the manufacture of polymers, pharmaceuticals, organic compounds, herbicides, pesticides and other chemicals

Desenvolvimento de metodologias analíticas alternativas por cromatografia gasosa para análise de biodiesel

Since the beginning of the National Program for Production and Use of Biodiesel in Brazil, in 2004, different raw materials were evaluated for biodiesel production, trying to combine the agricultural diversity of the country to the desire to reduce production coasts. To determine the chemical composition of biodiesel produced from common vegetables oils, international methods have been used widely in Brazil. However, for analyzing biodiesel samples produced from some alternative raw materials analytical problems have been detected. That was the case of biodiesel from castor oil. Due the need to overcome these problems, new methodologies were developed using different chromatographic columns, standards and quantitative methods. The priority was simplifying the equipment configuration, realizing faster analyses, reducing the costs and facilitating the routine of biodiesel research and production laboratories. For quantifying free glycerin, the ethylene glycol was used in instead of 1,2,4-butanetriol, without loss of quality results. The ethylene glycol is a cheaper and easier standard. For methanol analyses the headspace was not used and the cost of the equipment used was lower. A detailed determination of the esters helped the deeper knowledge of the biodiesel composition. The report of the experiments and conclusions of the research that resulted in the development of alternative methods for quality control of the composition of the biodiesel produced in Brazil, a country with considerable variability of species in agriculture, are the goals of this thesis and are reported in the following pages

Unraveling the function of bacterial-type phosphoenolpyruvate carboxylase in vascular plants

Thesis (Master, Biology) -- Queen's University, 2016-09-29 20:09:46.997

Aplicaciones del Caos y la Complejidad en la Cadena de Suministros del Sector Agroindustrial

La presente investigación consiste en determinar las aplicaciones existentes de las teorías del caos y las teorías de la complejidad en la cadena de suministro del sector agroindustrial colombiano. Además, tiene como propósito describir el sector de la agroindustria y la cadena de suministro, identificar los modelos de caos y complejidad y posteriormente determinar cuáles de éstos son aplicables al sector. Se define el caos como una sub-disciplina de las matemáticas que estudia sistemas complejos o dinámicos y tiene inmerso implicaciones filosóficas; por otra parte complejidad es la cualidad que adquiere un sistema en el que hay diversos componentes relacionados. Se ha identificado que en el ámbito colombiano existen diferentes estudios enfocados en la construcción de modelos agroindustriales, donde se adopta el concepto de complejidad para calificar el atributo de dichos modelos que involucran la armonización e integración de diferentes actores, desde los productores hasta los consumidores. En este estudio se emplea un estudio monográfico de tipo documental teniendo como unidad de análisis la cadena de suministro del sector agroindustrial. Los resultados indican que las teorías del caos y complejidad se encuentran presentes dentro de la cadena de suministros del sector agroindustrial colombiano, ya que en ella se ocurre la interconexión entre productores, procesadores y comercializadores, interactuando entre ellos y presentando alteraciones en su comportamiento económico a lo largo del tiempo en función de variaciones de las condiciones iniciales influenciadas por variables macroeconómicas, ambientales, sociales y políticas.