Chankrabbe2019

Sodium loss at the anode in the initial sodiation process significantly reduces the energy density of sodium-ion batteries (SIBs). Here, a high-capacity Na2S/C nanocomposite featuring ultrafine Na2S nanoclusters ( less then 2 nm) confined in ZIF-8-derived microporous N-doped carbon is fabricated and employed as a cathode presodiation reagent to compensate for this sodium loss and increase the energy density of SIBs. The ultrafine size of Na2S enables fast reaction kinetics for sodium extraction and the carbon matrix provides good electronic conductivity. Also, the overall particle size of the Na2S/C nanocomposite (∼40 nm) is close to that of conductive additive. The above features enable it to replace a partial amount of conductive additive and compensate for the sodium loss at the anode concurrently. CDK phosphorylation As a demonstration, the Na3V2(PO4)3 electrode with 5 wt % Na2S/C and 5 wt % carbon black was fabricated, and it displayed a 19 mAh g-1 higher initial charge specific capacity than that of the counterpart with 10% carbon black without the addition of Na2S/C, realizing an increased energy density from 178 to 263 Wh kg-1 in the full cell configuration pairing with a hard carbon anode. Moreover, a stable cycling performance up to 200 cycles with an average capacity loss of 0.024 mAh g-1 per cycle was achieved for the presodiated Na3V2(PO4)3 electrode.Poly- and perfluoroalkyl substances (PFAS) are contaminants of emerging Arctic concern and are present in the marine environments of the polar regions. Their input to and fate within the marine cryosphere are poorly understood. We conducted a series of laboratory experiments to investigate the uptake, distribution, and release of 10 PFAS of varying carbon chain length (C4-C12) in young sea ice grown from artificial seawater (NaClsolution). We show that PFAS are incorporated into bulk sea ice during ice formation and regression analyses for individual PFAS concentrations in bulk sea ice were linearly related to salinity (r2 = 0.30 to 0.88, n = 18, p less then 0.05). This shows that their distribution is strongly governed by the presence and dynamics of brine (high salinity water) within the sea ice. Furthermore, long-chain PFAS (C8-C12), were enriched in bulk ice up to 3-fold more than short-chain PFAS (C4-C7) and NaCl. This suggests that chemical partitioning of PFAS between the different phases of sea ice also plays a role in their uptake during its formation. During sea ice melt, initial meltwater fractions were highly saline and predominantly contained short-chain PFAS, whereas the later, fresher meltwater fractions predominantly contained long-chain PFAS. Our results demonstrate that in highly saline parts of sea ice (near the upper and lower interfaces and in brine channels) significant chemical enrichment (ε) of PFAS can occur with concentrations in brine channels greatly exceeding those in seawater from which it forms (e.g., for PFOA, εbrine = 10 ± 4). This observation has implications for biological exposure to PFAS present in brine channels, a common feature of first-year sea ice which is the dominant ice type in a warming Arctic.Functional nanomaterials are one of the potential carriers for drug delivery, whereas there are many prerequisites for this purpose. The carrier should be monodispersed, be fluorescent, and have a proper nanostructure to keep/release drug molecules to achieve controlled release, although preparing a nanomaterial which fulfills all the demands is still very challenging. In this paper, we show the preparation of monodispersed nanoporous amorphous titania submicron particles with fluorescent property. They adsorb a model drug molecule-ibuprofen-with their surface coverage up to 100%. Such a perfect loading does not decrease the fluorescent intensity because of any quenching effects but even maximize it. We also demonstrate the release behavior of IBU into simulated body fluid. Interestingly, the present carrier releases most of IBU in 6 h, whereas that modified with the polyethylene glycol moiety takes 48 h to finish releasing IBU, indicating its potential for controlled release applications.Interest in unnatural α-amino acids has increased rapidly in recent years in areas ranging from protein design to medicinal chemistry to materials science. Consequently, the development of efficient, versatile, and straightforward methods for their enantioselective synthesis is an important objective in reaction development. In this report, we establish that a chiral catalyst based on nickel, an earth-abundant metal, can achieve the enantioconvergent coupling of readily available racemic alkyl electrophiles with a wide variety of alkylzinc reagents (11.1 ratio) to afford protected unnatural α-amino acids in good yield and ee. This cross-coupling, which proceeds under mild conditions and is tolerant of air, moisture, and a broad array of functional groups, complements earlier approaches to the catalytic asymmetric synthesis of this valuable family of molecules. We have applied our new method to the generation of several enantioenriched unnatural α-amino acids that have previously been shown to serve as useful intermediates in the synthesis of bioactive compounds.The chemistry of discrete molecular chains constituted by metals in low oxidation states, displaying metal-metal proximity and stabilized by suitable metal-bridging, assembling ligands comprising at least one soft donor atom is comprehensively reviewed; complexes with a single (hard or soft) bridging atom (e.g., μ-halide, μ-sulfide, or μ-PR2 etc.) as well as "closed" metal arrays (that fall in the realm of cluster chemistry) are excluded. The focus is on transition metal-based systems, with few excursions to cases combining transition and post-transition elements. Most relevant supporting ligands have neutral C, P, O, or S donor (mainly, N-heterocyclic carbene, phosphine, ether, thioether) or anionic donor (mainly phenyl, ylide, silyl, phosphide, thiolate) groups. A supporting-ligand-based classification of the metal chains is introduced, using as the classifying parameter the number of "bites" (i.e., ligand bridges) subtending each intermetallic separation. The ligands are further grouped according to the number of donor atoms interacting with the metal chain (called denticity in the following) and the column of the Periodic Table to which the set of donor atoms belongs (in ascending order).