Actividad antihipóxica y actividad antioxidante de semilas de Hibiscus esculentus

The antihypoxic and antioxidant activities of Hibiscus esculentus seeds were investigated employing eight in vitro assay systems. Antihypoxic activity was investigated in two models, haemic and circulatory. The effects were pronounced in both models of hypoxia. The antihypoxic effects were dose-dependent. The results indicated that the extracts have a protective effect against hypoxia induced lethality in mice. The extracts showed antioxidant activity in some models. IC50 for DPPH radical-scavenging activity was 234 ± 8.9 μg ml-1. The extracts showed weak nitric oxide-scavenging activity between 0.1 and 1.6 mg ml-1. The extracts showed weak Fe2+ chelating ability. IC50 were 150 ± 13 μg ml-1. The extracts also exhibited low antioxidant activity in the linoleic acid model but were capable of scavenging hydrogen peroxide in a concentration dependent manner. The total amount of phenolic compounds in each extract was determined as gallic acid equivalents and total flavonoid contents were calculated as quercetin equivalents from a calibration curve. Pharmacological effects may be attributed, at least in part, to the presence of phenols and flavonoids in the extracts.La actividad antihipóxica y antioxidante de semillas de Hibiscus esculentus fue investigada empleando ocho ensayos in vitro. La actividad antihipóxica fue investigada en dos modelos, uno de caracter hemínico y otro circulatorio. Los efectos fueron pronunciados en ambos modelos de hipoxia. Los efectos antihipóxicos fueron dependientes de la dosis. Los resultados indican que los extractos tienen un efecto protector contra la letabilidad inducida por hipoxia en ratones. Los extractos mostraron actividad antioxidante en algunos modelos. El IC50 para la actividad captadora de radicales fue 234 ± 8.9 μg ml-1. Los extractos muestran una débil actividad captadora de óxido nítrico comprendida entre 0.1 y 1.6 mg ml-1. Los extractos muestran una débil capacidad quelatante de Fe2+. El IC50 fue de 150 ± 13 μg ml-1. Los extractos también muestran una baja actividad antioxidante en modelos con ácido linoleico aunque fueron capaces de eliminar peróxido de hidrógeno en una manera dependiente de la concentración. La concentración de compuestos fenólicos totales en cada extracto fue determinado como equivalents de ácido gálico y el contenido total de flavonoides fue calculado como equivalentes de quercitina para la curva de calibración. Los efectos farmacológicos pueden ser atribuidos, al menos en parte, a la presencia de fenoles y flavonoides en el extracto

The antioxidant activity of wild medlar (Mespilus germanica L.) fruit, stem bark and leaf

The medlar is an edible fruit. Modern medicine has recognized its healing properties in the treatment of some diseases. There is no scientific data in the literature about the antioxidant activity of methanol or aqueous extract of medlar fruit, leaf or stem bark. Antioxidant activities of these parts were evaluated by employing six test systems. Stem bark extract (aqueous and methanol) showed best activity in 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity with IC50 = 10.7 ± 0.6 and 11.4 ± 0.8 μgml-1, respectively. All extracts showed weak Fe2+ chelating ability. Methanol extract of fruit had better activity in nitric oxide scavenging model than others (IC50 = 247 ± 12.2 μgml-1). The leaves and bark extracts showed good reducing power than fruit extract. In reducing powers, there were no significant differences (p > 0.05) among the stem bark and leaves extracts that were comparable with vitamin C (p< 0.05). Extracts exhibited good antioxidant activity in the ferric thiocyanate (FTC) method. They manifested almost the same pattern of activity as vitamin C and butylated hydroxyanisole (BHA) at different incubation times (until 72nd hour) but stem bark extract showed higher peroxidation inhibition than vitamin C and BHA at the 96th hour (p < 0.05). The extracts were capable of scavenging H2O2 in a concentration-dependent manner. Leaves methanol extract showed good activity that was comparable with quercetin (p > 0.05). Bark and leaf extracts had higher total phenolic and flavonoid contents than fruit.Keywords: Antioxidant activity, free radical scavenging, Mespilus germanica, medlar, phenolic contents, flavonoids content

Dynamics of double emulsion break-up in three phase glass capillary microfluidic devices

Pinch-off of a compound jet in 3D glass capillary microfluidic device, which combines co-flowing and countercurrent flow focusing geometries, was investigated using an incompressible three-phase axisymmetric Volume of Fluid–Continuum Surface Force (VOF–CSF) numerical model. The model showed good agreement with the experimental drop generation and was capable of predicting formation of core/shell droplets in dripping, narrowing jetting and widening jetting regimes. In dripping and widening jetting regimes, the presence of a vortex flow around the upstream end of the necking thread facilitates the jet break-up. No vortex flow was observed in narrowing jetting regime and pinch-off occurred due to higher velocity at the downstream end of the coaxial thread compared to that at the upstream end. In all regimes, the inner jet ruptured before the outer jet, preventing a leakage of the inner drop into the outer fluid. The necking region moves at the maximum speed in the narrowing jetting regime, due to the highest level of shear at the outer surface of the thread. However, in widening jetting regime, the neck travels the longest distance downstream before it breaks

Double emulsion production in glass capillary microfluidic device: Parametric investigation of droplet generation behaviour

A three-phase axisymmetric numerical model based on Volume of Fluid–Continuum Surface Force (VOF–CSF) model was developed to perform parametric analysis of compound droplet production in three-phase glass capillary devices that combine co-flow and countercurrent flow focusing. The model predicted successfully generation of core–shell and multi-cored double emulsion droplets in dripping and jetting (narrowing and widening) regime and was used to investigate the effects of phase flow rates, fluid properties, and geometry on the size, morphology, and production rate of droplets. As the outer fluid flow rate increased, the size of compound droplets was reduced until a dripping-to-jetting transition occurred. By increasing the middle fluid flow rate, the size of compound droplets increased, which led to a widening jetting regime. The jetting was supressed by increasing the orifice size in the collection capillary or increasing the interfacial tension at the outer interface up to 0.06 N/m. The experimental and simulation results can be used to encapsulate CO2 solvents within gas-permeable microcapsules

Actividad antioxidante de extractos metanólicos de Ferula assafoetida y la composición de su aceite esencial

The antioxidant activity of the aerial parts of Ferula assafoetida was determined by employing various in vitro assay systems. IC50 for DPPH radical-scavenging activity was 380 ± 12 mg ml-1. The extracts showed good nitric oxide-scavenging activity (IC50 was 270 ± 3) and Fe2+ chelating ability (IC50 was 0.57 ± 0.02 mg ml-1). The peroxidation inhibition (antioxidant activity) of the extracts exhibited values from 82% (at 24 hrs) and 88% (at 72 hrs). The extract exhibited a fairy weak reducing power at 25-800 μg ml-1 of extracts which was not comparable with Vitamin C (p < 0.001). The tested extracts exhibited very low antioxidant activity. In addition, the chemical composition of the essential oil of the aerial parts was determined. The major compounds were phenol, 2-methyl-5-(1-methyl ethyl) (18.2 %), α.-Bisabolol (10.4%) and Arsine triethyl (8.7 %). Total phenol compounds, as determined by the Folin Ciocalteu method, were 94.8 ± 5.9 mg gallic acid equivalent/g of extract powder and the total flavonoid content (by AlCl3 method) was 90.9 ± 6.3 mg quercetin equivalent/g of extract powder.La actividad antioxidante de las partes aéreas de Ferula assafoetida se determinó empleando varios sistemas de ensayos in vitro. El IC50 de la actividad captadora de radicales de DPPH fue 380 ± 12 mg ml-1. Los extractos también mostraron una buena actividad captadora de óxido nítrico (IC50 fue 270 ± 3) y capacidad quelatante de Fe2+ (IC50 fue 0.57 ± 0.02 mg ml-1). La inhibición de la peroxidación (actividad antioxidante) de los extractos mostró valores del 82% (a las 24 horas) y 88% (a las 72 horas). El extracto mostró un ligero descenso del poder reductor con 25- 800 μg ml-1 de extracto que no fue comparable con la vitamina C (p < 0.001). Los extractos ensayados mostraron una muy baja actividad antioxidante. Además, la composición química del aceite esencial de las partes aéreas fue determinada. Los principales compuestos fueron fenol, 2-metil-5-(1-metil etilo) (18.2 %), α.-Bisabolol (10.4%) and Arsine trietilo (8.7 %). Los fenoles totales, determinados por el método de Folin-Ciocalteau, fue de 94.8 ± 5.9 mg de equivalentes de ácido gálico/g de extracto en polvo y el contenido total de flavonoides (por el método del AlCl3) fue de 90.9 ± 6.3 mg de equivalentes de quercitina/g de extracto en polvo

Carbonation of lime-based materials under ambient conditions for direct air capture

Carbonation of lime-based materials at high temperatures has been extensively explored in the processes for decarbonisation of the power and industrial sectors. However, their capability to capture carbon dioxide from air at realistic ambient conditions in direct air capture technologies is less explored. In this work, lime and hydrated lime samples are exposed to ambient air for prolonged durations, as well as to calcination/ambient-carbonation cycles, to assess their carbonation performance. It is shown that the humidity plays a key role in carbonation of lime under ambient conditions. Furthermore, faster weathering and higher conversions are demonstrated by hydrated lime, showing a carbonation conversion of 70% after 300 h. Importantly, it was found that there was a negligible difference in the carbonation conversions during five calcination/ambient-carbonation cycles, which can be explained by simultaneous reactivation of cycled material by moist air. These findings indicated that lime-based materials are suitable for carbon dioxide capture from ambient air employing cyclic processes, in a practical time-scale, and that humidity of air plays a key role

Demonstration of a kW-scale solid oxide fuel cell-calciner for power generation and production of calcined materials

Carbonate looping (CaL) has been shown to be less energy-intensive when compared to mature carbon capture technologies. Further reduction in the efficiency penalties can be achieved by employing a more efficient source of heat for the calcination process, instead of oxy-fuel combustion. In this study, a kW-scale solid oxide fuel cell (SOFC)-integrated calciner was designed and developed to evaluate the technical feasibility of simultaneously generating power and driving the calcination process using the high-grade heat of the anode off-gas. Such a system can be integrated with CaL systems, or employed as a negative-emission technology, where the calcines are used to capture CO2 from the atmosphere. The demonstration unit consisted of a planar SOFC stack, operating at 750 °C, and a combined afterburner/calciner to combust hydrogen slip from the anode off-gas, and thermally decompose magnesite, dolomite, and limestone. The demonstrator generated up to 2 kWel,DC power, achieved a temperature in the range of 530–550 °C at the inlet of the afterburner, and up to 678 °C in the calciner, which was sufficient to demonstrate full calcination of magnesite, and partial calcination of dolomite. However, in order to achieve the temperature required for calcination of limestone, further scale-up and heat integration are needed. These results confirmed technical feasibility of the SOFC-calciner concept for production of calcined materials either for the market or for direct air capture (DAC)

Pilot-scale calcination of limestone in steam-rich gas for direct air capture

A novel polygeneration concept, which has been proposed recently, comprises a fuel-cell calciner integrated system in order to produce electricity and lime which can be used for direct air capture (DAC) to remove CO2 from the atmosphere. However, the scalability of the integrated system needs to be further studied. In this work, calcination of limestone under steam-rich conditions simulating flue gas from a solid oxide fuel cell (SOFC), and subsequent ambient carbonation has been explored. Limestone was calcined under two steam concentration (21% and 35% vol) conditions in a 25 kWth pilot-scale bubbling fluidised bed (BFB), and then exposed to ambient air to evaluate DAC performance. Samples were characterised in order to quantify the hydration and carbonation conversions over time and, therefore, their DAC capacity. It was observed that steam reduces calcination time, confirming its catalytic effect, while the calcination temperature remained the same regardless of the steam composition at the same CO2 partial pressure. Moreover, increasing steam concentration during calcination affected the material performance and DAC capacity at ambient conditions positively. Therefore, these findings demonstrate that limestone calcined under typical SOFC afterburner exhaust conditions is suitable as a DAC sorbent

CO2-brine-rock interactions: The effect of impurities on grain size distribution and reservoir permeability

The Bunter Sandstone formation in the UK’s southern North Sea has been identified as having the potential to store large volumes of CO2. Prior to injection, CO2 is captured with certain amounts of impurities, usually less than 5%vol. The dissolution of these impurities in formation water can cause chemical reactions between CO2, brine, and rock, which can affect the reservoir quality by altering properties such as permeability. In this study, we explored the effect of CO2 and impurities (NO2, SO2, H2S) on reservoir permeability by measuring changes in grain size distributions after a prolonged period of 9 months, simulating in situ experimental conditions. It was found that the effects of pure CO2 and CO2-H2S are relatively small, i.e., CO2 increased permeability by 5.5% and CO2-H2S decreased it by 5.5%. Also, CO2-SO2 slightly decreased permeability by 6.25%, while CO2-NO2 showed the most pronounced effect, reducing permeability by 41.6%. The decrease in permeability showed a correlation with decreasing pH of the formation water and this equally correlates with a decrease in geometric mean of the grain diameter. The findings from this study are aimed to be used in future modelling studies on reservoir performance during injection and storage, which also should account for the shifts in boundaries in the CO2 phase diagram, altering the reservoir properties and affecting the cost of storage