Recently, polyphenols have been found to affect blood lipids in animals in a similar manner as soluble dietary fibre. The aim was to assess whether an insoluble dietary fiber very rich in polyphenols has a beneficial effect on serum lipids in humans. In a double-blind randomized placebo-controlled clinical study with parallel arms, 88 volunteers with hypercholesterolemia were randomly assigned to consume daily either, fiber with insoluble 84% polyphenols 4 g twice a day (n = 43) or placebo (n = 45). Serum total, LDL and HDL cholesterol and triglycerides were assessed at baseline and after 4 weeks. The insoluble polyphenols consumption reduced the total cholesterol by 17.8 +/- 6.1% (p < 0.05), LDL cholesterol by 22.5 +/- 8.9% (p < 0.001), LDL: HDL cholesterol ratio by 26.2 +/- 14.3% (p < 0.001) and triglycerides by 16.3 +/- 23.4% (p < 0.05) at the end of the study compared with baseline. No significant differences were found during the study time in the placebo group for the lipid profile. The consumption of fiber very rich in insoluble polyphenols shows beneficial effects on human blood lipid profile and may be effective in prevention and treatment of hyperlipemia.
In this article, a biogas‐based Brayton cycle is integrated with a concentrated solar power facility. The gas turbine hot flue gas and the molten salts are used to generate steam for the regenerative Rankine cycle. The process model is solved as a nonlinear optimization problem within a multiperiod scheme to decide on the contribution of the energy resources and the operating conditions of the facility to meet a certain demand of power over a year mitigating the absence of solar availability. The steam turbine is responsible for power production while the gas turbine works mainly as a combustion chamber. In the South of Spain, an excess of biogas is available during summer yielding a production cost of electricity of 0.17 €/kWh with an investment of 380 M€ for a production facility of 25 MW. This plant is not yet economic.
This
work presents a two-stage approach for the design and evaluation
of the performance of solar central tubular receivers. First, the
unit design is obtained using a mixed-integer nonlinear programing
(MINLP) optimization problem, considering the radiation profile and
the weather of the location. Later, with the design fixed, the NLP
is solved to determine the performance of the receiver during a year.
Three different locations are studied (Almería, Arizona, and
Scotland), each of them with their characteristic radiation and weather.
The designs obtained show the effect of the location on the size of
the different elements of the receiver. The performance over a year
presents the heat-transfer features as well as the effect of the wind
speed profile affecting the convective heat transfer. The number of
trade-offs results in the need for a comprehensive analysis for the
design of these units toward reducing the pressure drop but considering
the increase of the thermal stress on the tubes.
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