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Blood storage promotes the rapid depletion of red blood cell (RBC) high-energy adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (DPG), which are critical regulators of erythrocyte physiology and function, as well as oxygen kinetics and posttransfusion survival. Sphingosine-1-phosphate (S1P) promotes fluxes through glycolysis. We hypothesized that S1P supplementation to stored RBC units would improve energy metabolism and posttransfusion recovery. We quantified S1P in 1929 samples (n = 643, storage days 10, 23, and 42) from the REDS RBC Omics study. We then supplemented human and murine RBCs from good storer (C57BL6/J) and poor storer strains (FVB) with S1P (1, 5, and 10 μM) before measurements of metabolism and posttransfusion recovery. Similar experiments were repeated for mice with genetic ablation of the S1P biosynthetic pathway (sphingosine kinase 1 [Sphk1] knockout [KO]). Sample analyses included metabolomics at steady state, tracing experiments with 1,2,3-13C3-glucose, proteomics, and analysis of end-of-storage posttransfusion recovery, under normoxic and hypoxic storage conditions. Storage promoted decreases in S1P levels, which were the highest in units donated by female or older donors. Supplementation of S1P to human and murine RBCs boosted the steady-state levels of glycolytic metabolites and glycolytic fluxes, ie the generation of ATP and DPG, at the expense of the pentose phosphate pathway. Lower posttransfusion recovery was observed upon S1P supplementation. All these phenomena were reversed in Sphk1 KO mice or with hypoxic storage. S1P is a positive regulator of energy metabolism and a negative regulator of antioxidant metabolism in stored RBCs, resulting in lower posttransfusion recoveries in murine models.

This paper proposes an optimal power flow model that takes into account the uncertainty in the probability distribution of wind power. The model can schedule controllable generators under any possible distribution of wind power to ensure the safe and economic operation of the system. Firstly, considering the incompleteness of historical wind power data, the paper models the uncertainty of wind power using second-order moments of probability distribution and their fluctuation intervals. Subsequently, a robust optimal power flow model based on probability distribution model and joint chance constraints is established. The Lagrangian duality theorem is then employed to eliminate random variables from the optimization model, transforming the uncertainty model into a deterministic linear matrix inequality problem. Finally, a convex optimization algorithm is used to solve the deterministic problem, and the results are compared with traditional chance-constrained optimal power flow model. The feasibility and effectiveness of the proposed method are validated through case study simulations. [ABSTRACT FROM AUTHOR]

Under the current trend of power electronics in energy systems, a high percentage of renewable energy transports clean energy to the grid through grid-connected inverters. The pulse-width modulation (PWM) technique brings high-order harmonics near to the switching frequency, and LCL filters with low-pass characteristics become the common choice for grid-connected inverters. However, the low-order harmonics caused by nonideal switching characteristics are difficult to filter out, and the new resonance point introduced by the LCL filter causes a security problem for the energy systems. Firstly, the generation mechanism of the 6 k ± 1 order harmonic and high-frequency resonance from a PV grid-connected inverter is analyzed. Then, a virtual resistor is constructed by the active damping method to absorb the resonant component. Meanwhile, this paper also presents an adaptive modulation voltage compensation method to decrease the low-order harmonics. Finally, the actual measured data of user photovoltaic (PV) and multiple comparative simulations verify these theories. Simulation results show that the proposed coordinated control algorithm reduces the peak of the resonance point, and the rate of low-order harmonics mitigation is more than 50%. The proposed method is suitable for various operating conditions. [ABSTRACT FROM AUTHOR]