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Phenylethanoid glycosides (PhGs) are generally water-soluble phenolic compounds that occur in many medicinal plants. Until June 2020, more than 572 PhGs have been isolated and identified. PhGs possess antibacterial, anticancer, antidiabetic, anti-inflammatory, antiobesity, antioxidant, antiviral, and neuroprotective properties. Despite these promising benefits, PhGs have failed to fulfill their therapeutic applications due to their poor bioavailability. The attempts to understand their metabolic pathways to improve their bioavailability are investigated. In this review article, we will first summarize the number of PhGs compounds which is not accurate in the literature. The latest information on the biological activities, structure-activity relationships, mechanisms, and especially the clinical applications of PhGs will be reviewed. The bioavailability of PhGs will be summarized and factors leading to the low bioavailability will be analyzed. Recent advances in methods such as bioenhancers and nanotechnology to improve the bioavailability of PhGs are also summarized. The existing scientific gaps of PhGs in knowledge are also discussed, highlighting research directions in the future.

Counter-flowing thermal fluids are conducive to generate a homogeneous temperature difference on thermoelectric (TE) generator. This study allowed the hot and cold fluids of having constant inlet temperature to flow in the opposite, and examined TE performance of module at different flow rates. The results show that TE performance gradually increases with flow rate in the initial stage of fluid flow, and reaches a transient peak value after the module surfaces are completely covered by thermal fluids, and then tends to be stable. High flow rate leads to larger performance and reduces the time of achieving them. Effect of flow rate on stable performance is slightly more than that of inlet temperature of thermal fluids, which makes regulating the flow rate to be a feasible way to harvest more heat for TE conversion. Module features present a specific trend and provide the supports for the benefit of counter-flowing thermal fluids. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Thermoelectric (TE) performance of a three-dimensional (3-D) TE module is examined by exposing it between a pair of counter-flows of ideal fluids. The ideal fluids are thermal sources of TE module flow in the opposite direction at the same flow rate and generate temperature differences on the hot and cold surfaces due to their different temperatures at the channel inlet. TE performance caused by different inlet temperatures of thermal fluids are numerically analyzed by using the finite-volume method on 3-D meshed physical models and then compared with those using a constant boundary temperature. The results show that voltage and current of the TE module increase gradually from a beginning moment to a steady flow and reach a stable value. The stable values increase with inlet temperature of the hot fluid when the inlet temperature of cold fluid is fixed. However, the time to get to the stable values is almost consistent for all the temperature differences. Moreover, the trend of TE performance using a fluid flow boundary is similar to that of using a constant boundary temperature. Furthermore, 3-D contours of fluid pressure, temperature, enthalpy, electromotive force, current density and heat flux are exhibited in order to clarify the influence of counter-flows of ideal fluids on TE generation. The current density and heat flux homogeneously distribute on an entire TE module, thus indicating that the counter-flows of thermal fluids have high potential to bring about fine performance for TE modules.

Counter-flowing thermal fluids are conducive to generate a homogeneous temperature difference on thermoelectric (TE) generator. This study allowed the hot and cold fluids of having constant inlet temperature to flow in the opposite, and examined TE performance of module at different flow rates. The results show that TE performance gradually increases with flow rate in the initial stage of fluid flow, and reaches a transient peak value after the module surfaces are completely covered by thermal fluids, and then tends to be stable. High flow rate leads to larger performance and reduces the time of achieving them. Effect of flow rate on stable performance is slightly more than that of inlet temperature of thermal fluids, which makes regulating the flow rate to be a feasible way to harvest more heat for TE conversion. Module features present a specific trend and provide the supports for the benefit of counter-flowing thermal fluids. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Thermoelectric (TE) performance of a three-dimensional (3-D) TE module is examined by exposing it between a pair of counter-flows of ideal fluids. The ideal fluids are thermal sources of TE module flow in the opposite direction at the same flow rate and generate temperature differences on the hot and cold surfaces due to their different temperatures at the channel inlet. TE performance caused by different inlet temperatures of thermal fluids are numerically analyzed by using the finite-volume method on 3-D meshed physical models and then compared with those using a constant boundary temperature. The results show that voltage and current of the TE module increase gradually from a beginning moment to a steady flow and reach a stable value. The stable values increase with inlet temperature of the hot fluid when the inlet temperature of cold fluid is fixed. However, the time to get to the stable values is almost consistent for all the temperature differences. Moreover, the trend of TE performance using a fluid flow boundary is similar to that of using a constant boundary temperature. Furthermore, 3-D contours of fluid pressure, temperature, enthalpy, electromotive force, current density and heat flux are exhibited in order to clarify the influence of counter-flows of ideal fluids on TE generation. The current density and heat flux homogeneously distribute on an entire TE module, thus indicating that the counter-flows of thermal fluids have high potential to bring about fine performance for TE modules.