Atom-Economic Synthesis of Zeolites.

Zeolites are typically synthesized in the presence of strong alkaline or fluoride species, which is not atom-economic for zeolite synthesis due to the high solubility of strong alkaline and fluoride species to silica. One of the solutions for this issue is to reduce solubility of silica in the zeolite synthesis, but it is challenging. Herein, we show that nucleation and growth of zeolites can occur under near neutral conditions, giving an atom-economical synthesis of zeolites with almost full silica utilization due to very low silica solubility.

Palladium catalysis enables cross-coupling-like S2-glycosylation of phenols.

Despite their importance in life and material sciences, the efficient construction of stereo-defined glycosides remains a challenge. Studies of carbohydrate functions would be advanced if glycosylation methods were as reliable and modular as palladium (Pd)-catalyzed cross-coupling. However, Pd-catalysis excels in forming sp-hybridized carbon centers whereas glycosylation mostly builds sp-hybridized C-O linkages.

Nonenzymatic Stereoselective -Glycosylation of Polypeptides and Proteins.

Here we report a nonenzymatic glycosylation reaction that builds axial -glycosidic bonds under biorelevant conditions. This strategy is enabled by the design and use of allyl glycosyl sulfones as precursors to glycosyl radicals and exploits the exceptional functional group tolerance of radical processes. Our method introduces a variety of unprotected glycosyl units to the cysteine residues of peptides in a highly selective fashion.

A Radical Approach to Making Unnatural Amino Acids: Conversion of C-S Bonds in Cysteine Derivatives into C-C Bonds.

Here we report a general approach to make unnatural amino acids from readily available cysteine derivatives. This method capitalizes on an intramolecular radical substitution process that generates alkyl radicals through C-S cleavage. The resulting alkyl radicals partook in diverse C-C bond forming events.

[Sources and Distribution of Phosphorus in Sediments of the Jinpen Reservoir].

In order to explore the sources and distribution of phosphorus in sediments of a stratified water source reservoir, the total phosphorus (TP) content and distribution of phosphorus fractions in sedimentation particles and sediments of the Jinpen Reservoir of Xi'an were analyzed from March to November in 2017. The results showed that the TP content in the surface sediments of the Jinpen Reservoir was obviously affected by the deposition of particulate phosphorus (PP), and the correlation coefficient was 0.8775.

[Migration Characteristics of Manganese During Rainfall Events and Its Impacts on Water Quality in a Drinking Water Source Reservoir].

In view of the problem of excessive manganese concentrations in the Xi'an Jinpen Reservoir during the flood season in 2017, the vertical distribution of manganese in density currents and its occurrence pattern were monitored at multiple monitoring sections along the upstream reaches to the main basin. The influences of density currents plunging into the reservoir on the migration and transformation of Mn were studied, and sedimentation, output, and deposition of manganese in the reservoir water were also specifically estimated during a single, typical storm runoff process. Devices for avoiding high turbidity and high load inflows in rainfall events were proposed.

Catalytic Asymmetric Synthesis of α-Tetrasubstituted α-Trifluoromethyl Homoallylic Amines by Ir-Catalyzed Umpolung Allylation of Imines.

A general and mild method to prepare enantioenriched α-trifluoromethyl, α-stereogenic homoallylic amines is established. This reaction, which involves an Ir-catalyzed umpolung allylation of imines and a 2-aza-Cope rearrangement cascade, could yield both tetrasubstituted and trisubstituted stereocenters. This transformation employs readily available starting materials and displays broad substrate scope.

Controlling reduced iron and manganese in a drinking water reservoir by hypolimnetic aeration and artificial destratification.

The concentrations of iron (Fe) and manganese (Mn) in the water column have extremely important effects on the water quality of drinking water reservoirs; however, reservoirs often experience problematic Fe and Mn levels during seasonal stratification and rainfall events. Water-lifting aerators (WLAs) were deployed in the Jinpen Reservoir to control these issues with Fe and Mn at the source via bottom aeration and artificial destratification. In this study, variations of Fe and Mn concentrations in the water column, porewater, and sediments, were used to characterize behaviors of reduced Fe and Mn under the conditions of hypolimnetic aeration and artificial destratification during periods of hypolimnion hypoxia and rainfall events.

Ni-Catalyzed Suzuki-Miyaura Cross-Coupling of α-Oxo-vinylsulfones To Prepare C-Aryl Glycals and Acyclic Vinyl Ethers.

We demonstrate that readily available and bench-stable α-oxo-vinylsulfones are competent electrophiles in Ni-catalyzed Suzuki-Miyaura cross-coupling reactions. The C-sulfone bond in the α-oxo-vinylsulfone motif is cleaved chemoselectively in these reactions, furnishing C-aryl glycals or acyclic vinyl ethers in high yields. These reactions proceed under mild conditions and tolerate a remarkable scope of heterocycles and functional groups.