Chance constrained optimal power flow (OPF) has been recognized as a promising framework to manage the risk from variable renewable energy (VRE). In presence of VRE uncertainties, this paper discusses a distributionally robust chance constrained approximate AC-OPF. The power flow model employed in the proposed OPF formulation combines an exact AC power flow model at the nominal operation point and an approximate linear power flow model to reflect the system response under uncertainties. The ambiguity set employed in the distributionally robust formulation is the Wasserstein ball centered at the empirical distribution. The proposed OPF model minimizes the expectation of the quadratic cost function w.r.t. the worst-case probability distribution and guarantees the chance constraints satisfied for any distribution in the ambiguity set. The whole method is data-driven in the sense that the ambiguity set is constructed from historical data without any presumption on the type of the probability distribution, and more data leads to smaller ambiguity set and less conservative strategy. Moreover, special problem structures of the proposed problem formulation are exploited to develop an efficient and scalable solution approach. Case studies are carried out on IEEE 14 and 118 bus systems to show the accuracy and necessity of the approximate AC model and the attractive features of the distributionally robust optimization approach compared with other methods to deal with uncertainties.

Chromatographic media with synchronously large protein adsorption capacity and high processing flux are highly desired in protein separation; however, the creation of such materials still faces enormous challenges. Herein, a robust strategy to develop highly carboxylated monolithic media by combining nanofibrous aerogels' forming technique and an in situ modification approach is reported. The obtained ion-exchange nanofibrous aerogels (IENFAs) exhibit a unique cellular structure consisting of flexible ceramic nanofibers and a functional polymer wrapping layer, endowing them with outstanding underwater superelasticity and compressive fatigue resistance (nearly no plastic deformation after 1000 compressive cycles). Benefiting from the interconnected nanofibrous cellular structure, good hydrophilicity, high carboxylation, and excellent mechanical properties, the IENFAs exhibit synchronously promoted static (2.9 × 10 3 mg g −1 ) and dynamic (1.7 × 10 3 mg g −1 ) lysozyme adsorption capacities and improved buffer flux (2.17 × 10 4 L m −2 h −1 , gravity driven), which are superior to these reported nanofibrous materials and commercial ion-exchange membranes. The IENFAs also possess outstanding performance stability, easy operation, and excellent regenerability. Moreover, the IENFA-packed column could directly and continuously separate lysozyme from egg white solely driven by gravity, highlighting their excellent practical application performance. This work may provide a new avenue to design and develop next-generation high-performance chromatographic media for bioseparation.

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Photoluminescence properties of Tb3+ and Ce3+ singly doped and Ce3+/Tb3+-codoped RE2Si4N6C (RE = Lu, Y, and Gd) phosphors were investigated. Tb3+ shows similar luminescence properties in RE2Si4N6C (RE = Lu, Y, and Gd) host lattices and emits bright green light under UV excitation around 300 nm. The luminescence properties of Ce3+ in RE2Si4N6C host lattices are influenced by the size of the RE3+ ions (Lu2Si4N6C and Y2Si4N6C vs Gd2Si4N6C). Both Ce3+-activated Lu2Si4N6C and Y2Si4N6C phosphors exhibit a broad band emission in the wavelength range of 450−750 nm with peak center at about 540 nm, while Ce3+-activated Gd2Si4N6C shows a broad emission band in the wavelength range of 500−800 nm with peak center at about 610 nm. This difference is ascribed to the different site occupations of Ce3+ on the two crystallographic sites in Gd2Si4N6C as compared to the Y and Lu compounds. In Ce3+/Tb3+-codoped RE2Si4N6C (RE = Lu, Y, and Gd) phosphors, it is observed that energy transfer takes place from Ce3+ to Tb3+ in Ce3+/Tb3+-codoped Lu2Si4N6C and Y2Si4N6C but in the reversed direction from Tb3+ to Ce3+ in Ce3+/Tb3+-codoped Gd2Si4N6C, depending on the position of the 5d level of Ce3+ versus the 5D4 level of Tb3+. The potential applications of these phosphors are pointed out.