Corrosion Inhibition in CO2-Saturated Brine by Nd3+ Ions.

This study reports the use of an inorganic corrosion inhibitor to mitigate dissolved CO2-induced corrosion. Using electrochemical techniques (polarization curves, open circuit potential, polarization resistance, and electrochemical impedance), the effect of adding Nd3+ ions on the corrosion resistance of X52 steel immersed in CO2-saturated brine at 20 °C and 60 °C was evaluated. The polarization curves showed that the Icorr values tend to decrease with increasing Nd3+ ion concentration, up to the optimal inhibition concentration, and that the corrosion potential increases at nobler values. Open circuit potential measurements showed a large increase in potential values immediately after the addition of the Nd3+ ions. Similarly, polarization resistance measurements showed similar trends. It was observed that regardless of temperature, Nd3+ ions can reduce the corrosion rate by more than 97% at doses as low as 0.001 M. Electrochemical impedance measurements confirmed the formation of a protective layer on the steel surface, which caused an increase in the magnitude of the impedance module and phase angle, which indicates an increase in the resistance to charge transfer and capacitive properties of the metallic surface. The characterization of the metallic surface showed that the protective layer was formed by Nd carbonates, whose formation was due to a CO2 capture process.

Inhibition of X52 Corrosion in CO2-Saturated Brine by a Dialkyl-Diamide from Coffee Bagasse Oil.

This work reports the performance of a green corrosion inhibitor with double hydrocarbon chain. The evaluated inhibitor was a dialkyl-diamide from coffee bagasse oil and its electrochemical behavior was evaluated on an API-X52 steel in CO2-saturated brine at 60 °C. The electrochemical behavior was determined by measurements of open circuit potential, polarization resistance, and electrochemical impedance spectroscopy. In addition, the thermodynamic parameters of the corrosion process were obtained in the temperature range from 40 °C to 80 °C. Electrochemical studies showed that the inhibitor is capable of suppressing metal dissolution by up to 99% at 25 ppm. On the other hand, the thermodynamic parameters indicate that when adding the inhibitor, there is a strong increase in both Ea and ΔH° values, and that as time increases, they decrease until reaching similar values to those observed in the absence of the inhibitor. Furthermore, ΔS° values tend to become more negative with immersion time because of the formation of a stable film on the metal surface.

Sweet Corrosion Inhibition by CO2 Capture.

The most practical and economical way to combat the problems derived from CO2 corrosion (sweet corrosion) is the use of corrosion inhibitors of organic origin. Its main protection mechanism is based on its ability to adsorb on the metal surface, forming a barrier between the metal surface and the aggressive medium. However, despite its excellent performance, its inhibition efficiency can be compromised with the increase in temperature as well as the shear stresses. In this study, the use of an inorganic inhibitor is proposed that has not been considered as an inhibitor of sweet corrosion. The reported studies are based on using LaCl3 as a corrosion inhibitor. Its behavior was evaluated on 1018 carbon steel using electrochemical measurements, such as potentiodynamic polarization curves, open-circuit potential measurements, linear polarization resistance measurements, and electrochemical impedance. The results showed an inhibition efficiency of the sweet corrosion process greater than 95%, and that the inhibition mechanism was different from the classic corrosion process in CO2-free electrolytes. In this case, it was observed that the inhibitory capacity of the La3+ cations is based on a CO2-capture process and the precipitation of a barrier layer of lanthanum carbonate (La2(CO3)3).

Estudo comparativo da sutura contínua e simples em anastomose microvascular da artéria carótida comum em ratos / Comparative stud of simples and continuous sutures in microvascular anastomosis of the carotid common artery in rats

O objetivo deste estudo é avaliar, comparativamente, suturas contínuas e simples na artéria carótida de ratos. Foram utilizados 15 ratos wistar (rattus novergicus); as artérias carótidas comuns foram dissecadas, seccionadas e anstomosadas termino-terminal, utilizando-se sutura simples(ss) à direita e sutura contínua (sc) à esquerda. Os resultados obtidos com macroscopia demonstraram-se normais em 8 artérias (53,33 por cento) da ss e em 9 60 por cento da sc; estenose em 6 carótidas (40 por cento) da ss e em 4 (26,66 por cento) da sc. Apresentaram aneurismas 1 artéria (6,66 por cento) da ss e 2 (13,33 por cento) da sc. A microscopia demonstrou ausência de endotelização da sutura em 2 carótidas (13,33 por cento) da ss e 1 (66,66 por cento) da sc. A reação adventicial ocorreu em 7 artérias (46,66 por cento) da ss e 3da sc. O tempo de execução da suturas contínuas foi, em média, 40 por cento mais rápido. Concluiu-se que ambas as suturas promovem graus de estenoses, aneurismas e alterações microscópicas, sem diferença estatística significativa entre si, porém quando comparadas ao tempo de execução da anastomes a sutura contínua mostra-se mais rápida, tendo este dado uma diferença estatistcamente significante(P=0,0007)

Determination of the effective dose of an experimental fasciolicide in naturally and experimentally infected cattle.

The aim of the present study was to determine the effective dose of an experimental fasciolicide called compound alpha or 5-chloro-2-methylthio-6-(1-napthyloxy)1H-benzimidazole in experimentally and naturally infected cattle. In the first experiment, 24 fluke-free heifers were each infected with 800 metacercariae of Fasciola hepatica and re-infected on day 45 with other 600 cysts per animal. On day 75, when the animals had 4- and 10-week-old flukes respectively, they were divided into four groups (G) of six animals each according to fluke egg counts. Groups 1-3 received compound alpha at 10, 12 and 14 mg/kg/p.o., respectively. G4 remained as an untreated control. Twenty days after treatment, the animals were sacrificed for the recovery of flukes. Efficacy was assessed as a percentage of egg or fluke reduction relative to the untreated control. In the second experiment (naturally infected cattle), 24-year-old steers positive to F. hepatica eggs were blocked into four groups of five animals each. Groups 1-3 received compound alpha at 10, 12 and 14 mg/kg/p.o., respectively. Group 4 served as a non-treated control. All procedures to determine efficacy were carried out as mentioned in the first experiment. The results in the first study showed a percentage on egg reduction of 97.3, 100 and 100 and overall fluke reduction of 94.3, 100 and 100 for Groups 1-3, respectively. In the second study, the percentage of egg reduction was of 87.5, 99.1 and 100 and overall efficacy regarding fluke reduction was of 84.2, 99.6, and 100 for Groups 1-3, respectively. It is concluded that the effective dose selected for compound alpha was of 12 mg/kg/p.o. in cattle having an induced or natural F. hepatica infection.

Comparación de dos esquemas de profilaxis antimicrobiana en cirugía de vías biliares: un ensayo clínico controlado por sorteo / Comparison of two schemes of antimicrobial prophylaxis in biliary tracta curgery: a randomized clinicar trial

Objetivo del estudio. Comparar la eficacia en la profilaxis de la amoxicilina/clavulanato y de la combinación cefalotina y clindamicina en cirugía de vesícula y de vías biliares. Diseño. Estudio clínico controlado por sorteo con un evaluador ciego a la maniobra recibida. Lugar. Centro de tercer nivel de atención médica. Pacientes. Se incluyeron 42 pacientes que fueron sometidos a cirugía de vesícula y/o de vías biliares, y se distribuyeron en dos grupos: en el A 22 pacientes (cefalotina y clindamicina) y en el B 20 (amoxicilina/clavulanato). Intervenciones. A los pacientes del grupo A se les administraron por vía intravenosa: tres dosis de cefalotina (2 g al momento de la inducción de la anestesia y dos dosis adicionales de 1 g cada seis horas) y tres dosis de clindamicina de 600 mg (la primera al momento de la inducción anestésica seguido de dos dosis adicionales). A los pacientes del grupo B se les administraron tres dosis de amoxicilina/clavulanato 1000/200 mg IV (la primera durante la inducción de la anestesia y dos dosis subsecuentes con intervalos de seis horas). Mediciones y resultados principales. En el grupo A se presentaron seis infecciones de herida quirúrgica, una de las cuales se acompañó de bacteremia. En el grupo B no se registraron infecciones (Fisher, p<0.01). Se presentó un caso de flebitis en cada grupo Conclusiones. Nuestros resultados indican que la amoxicilina/clavulanato es un esquema útil para profilaxis de cirugía biliar, y más eficaz que la combinación de cefalotina y clindamicina