In-Cage Recombination Facilitates the Enantioselective Organocatalytic [1,2]-Rearrangement of Allylic Ammonium Ylides.

The [1,2]-rearrangement of allylic ammonium ylides is traditionally observed as a competitive minor pathway alongside the thermally allowed [2,3]-sigmatropic rearrangement. Concerted [1,2]-rearrangements are formally forbidden, with these processes believed to proceed through homolytic C-N bond fission of the ylide, followed by radical-radical recombination. The challenges associated with developing a catalytic enantioselective [1,2]-rearrangement of allylic ammonium ylides therefore lie in biasing the reaction pathway to favor the [1,2]-reaction product, alongside controlling a stereoselective radical-radical recombination event.

Sb/As immobilization and soil function improvement under the combined remediation strategy of modified biochar and Sb-oxidizing bacteria at a smelting site.

Antimony (Sb) and arsenic (As) lead to soil pollution and structural degradation at Sb smelting sites. However, most sites focus solely on Sb/As immobilization, neglecting the restoration of soil functionality. Here, we investigated the effectiveness of Fe/HO modified biochar (Fe@HO-BC) and Sb-oxidizing bacteria (Bacillus sp.

Ecological restoration affects the dynamic response of alkaline minerals dissolution in bauxite residue.

Regulating alkalinity is the key process to eliminating environmental risk and implementing sustainable management of bauxite residue. Nevertheless, continuous release of free alkali from the solid phase (mainly sodalite and cancrinite) is a major challenge for long-term stability of alkalinity in amended bauxite residue. In order to understand the dissolution behavior of sodalite and cancrinite, their dissolution kinetics under simulated pH conditions of 8, 9 and 10 were investigated.

Remediation potential of magnetic biochar in lead smelting sites: Insight from the complexation of dissolved organic matter with potentially toxic elements.

Magnetic biochar has been widely used in potentially toxic elements (PTEs) polluted soils due to its magnetic separation capability and synchronous immobilization for multiple metals. However, the contribution of magnetic biochar to soil dissolve organic material (SDOM) and its binding behavior with PTEs needs to be further clarified prior to its remediation application on lead smelting sites. In this study, multi-spectral techniques of excitation-emission matrix (EEM) fluorescence spectroscopy and two-dimensional FTIR correlation spectroscopy (2D-FTIR-COS) were used to explore the evolution characteristics of SDOM in the lead smelting site under the remediation of magnetic biochar, and to further analyze its affinity and binding behavior with Pb and As.

The assembly process and co-occurrence patterns of soil microbial communities at a lead smelting site.

The potential toxic elements of the site are diverse and complex, seriously threatening the land utilization potential and soil ecological function. Microbial community is critical to maintaining ecosystem function, their assembly processes and diversity play an essential role in predicting changes in soil ecological function. However, our understanding of the mechanisms that shape community composition and successional direction in complex polluted environments is very limited.

Enantioselective catalytic remote perfluoroalkylation of α-branched enals driven by light.

Herein, we report a photochemical organocatalytic method for the asymmetric introduction of perfluoroalkyl fragments (including the valuable trifluoromethyl moiety) at the remote γ-position of α-branched enals. The chemistry exploits the ability of extended enamines (dienamines) to form photoactive electron donor-acceptor (EDA) complexes with perfluoroalkyl iodides, which under blue light irradiation generate radicals through an electron transfer mechanism. The use of a chiral organocatalyst, derived from -4-hydroxy-l-proline, secures a consistently high stereocontrol while inferring complete site selectivity for the more distal γ position of the dienamines.

Effect of potentially toxic elements on soil multifunctionality at a lead smelting site.

Contaminated soil at smelting sites affects land utilization and environmental regulation, resulting in soil degradation. However, the extent to which potentially toxic elements (PTEs) contribute to site soil degradation and the relationship between soil multifunctionality and microbial diversity in the process remains poorly understood. In this study, we investigated changes in soil multifunctionality and the correlation between soil multifunctionality and microbial diversity under the influence of PTEs.

Photochemical Organocatalytic Functionalization of Pyridines via Pyridinyl Radicals.

We report a photochemical method for the functionalization of pyridines with radicals derived from allylic C-H bonds. Overall, two substrates undergo C-H functionalization to form a new C(sp)-C(sp) bond. The chemistry harnesses the unique reactivity of pyridinyl radicals, generated upon single-electron reduction of pyridinium ions, which undergo effective coupling with allylic radicals.

Combination of Biochemical, Molecular, and Synchrotron-Radiation-Based Techniques to Study the Effects of Silicon in Tomato ( L.).

The work focused on the analysis of two cultivars of tomato ( L.), Aragon and Gladis, under two different treatments of silicon, Low, 2 L of 0.1 mM CaSiO and High, 0.

Isothiourea-Catalyzed [2 + 2] Cycloaddition of C(1)-Ammonium Enolates and -Alkyl Isatins.

Enantioselective [2 + 2] cycloaddition of C(1)-ammonium enolates generated catalytically using the isothiourea HyperBTM with -alkyl isatins gives spirocyclic β-lactones. ring opening with an amine nucleophile generates isolable highly enantioenriched products in up to 92:8 dr and in >99:1 er.

A Desilylative Approach to Alkyl Substituted C(1)-Ammonium Enolates: Application in Enantioselective [2+2] Cycloadditions.

The catalytic generation of C(1)-ammonium enolates from the corresponding α-silyl-α-alkyl substituted carboxylic acids using the isothiourea HyperBTM is reported. This desilylative approach grants access to α-unsubstituted and α-alkyl substituted C(1)-ammonium enolates, which are typically difficult to access through traditional methods reliant upon deprotonation. The scope and limitations of this process is established in enantioselective [2+2]-cycloaddition processes with perfluoroalkylketones (31 examples, up to 96 % yield and >99 : 1 er), as well as selective [2+2]-cycloaddition with trifluoromethyl enones (4 examples, up to 75 % yield and >99 : 1 er).

Lewis Base-Catalysed Enantioselective Radical Conjugate Addition for the Synthesis of Enantioenriched Pyrrolidinones.

We report a catalytic asymmetric protocol for the preparation of chiral pyrrolidinones proceeding via a radical pathway. The chemistry exploits the combination of photoredox catalysis and Lewis base catalysis to realise the first example of asymmetric radical conjugate addition to α,β-unsaturated anhydrides and esters. The reaction is initiated by photoredox activation of N-arylglycines to generate, upon decarboxylation, α-amino radicals.

Improvements on physical conditions of bauxite residue following application of organic materials.

Soil formation and ecological rehabilitation is the most promising strategy to eliminate environmental risks of bauxite residue disposal areas. Its poor physical structure is nevertheless a major limitation to plant growth. Organic materials were demonstrated as effective ameliorants to improve the physical conditions of bauxite residue.

Novel Plant Growth-Promoting Bacteria Isolated from Bauxite Residue: The Application for Revegetation.

Microbial inoculation with appropriate inorganic-organic amendments is a promising strategy for ecological rehabilitation at bauxite residue disposal areas. Nevertheless, research on screening suitable plant growth-promoting bacteria with tolerance to highly sodic-alkalinity is very limited in the literature. In this study, novel plant growth-promoting bacteria isolated from bauxite residue were used to investigate their potential for revegetation.

Spatial distribution of toxic metal(loid)s at an abandoned zinc smelting site, Southern China.

Toxic metal(loid) (TM) soil pollution at large-scale non-ferrous metal smelting contaminated sites is of great concern in China, but there are no detailed reports relating to them. A comprehensive study was conducted to determine contamination characteristics and horizontal and vertical spatial distribution patterns of soils at an abandoned zinc smelting site in Southern China. The spatial distribution of TMs revealed that soil environmental quality was seriously threatened, with Cd, Zn, As, Pb and Hg being the main contaminants present.

Isothiourea-Catalyzed Enantioselective α-Alkylation of Esters via 1,6-Conjugate Addition to -Quinone Methides.

The isothiourea-catalyzed enantioselective 1,6-conjugate addition of -nitrophenyl esters to 2,6-disubstituted -quinone methides is reported. -Nitrophenoxide, generated in situ from initial -acylation of the isothiourea by the -nitrophenyl ester, is proposed to facilitate catalyst turnover in this transformation. A range of -nitrophenyl ester products can be isolated, or derivatized in situ by addition of benzylamine to give amides at up to 99% yield.

Insights into variations on dissolved organic matter of bauxite residue during soil-formation processes following 2-year column simulation.

Bauxite residue, an industrial alkaline solid waste, has a low organic carbon content which hinders plant growth. Dissolved organic matter (DOM) drives many biogeochemical processes including carbon storage and soil formation in soils. Input of exogenous organic materials may provide organic carbon and accelerate soil formation processes in bauxite residue.

Characteristics of Metabolites by Seed-Specific Inhibition of in L.

Fatty acid desaturase-2 (FAD2) is a key enzyme in the production of polyunsaturated fatty acids in plants. RNAi technology can reduce the expression of genes in seeds and acquire transgenic plants with a high oleic acid content, but the effect of seed-specific inhibition of expression on seed metabolites is not clear. Here we use widely targeted metabolomics to investigate the metabolites of normal-oleic-acid rapeseed (OA) and high-oleic-acid rapeseed (HOA) seeds, resulting in a total of 726 metabolites being detected.

Dark Energy Survey Year 1 Results: Cosmological Constraints from Cluster Abundances, Weak Lensing, and Galaxy Correlations.

We present the first joint analysis of cluster abundances and auto or cross-correlations of three cosmic tracer fields: galaxy density, weak gravitational lensing shear, and cluster density split by optical richness. From a joint analysis (4×2pt+N) of cluster abundances, three cluster cross-correlations, and the auto correlations of the galaxy density measured from the first year data of the Dark Energy Survey, we obtain Ω_{m}=0.305_{-0.

Appropriate human intervention stimulates the development of microbial communities and soil formation at a long-term weathered bauxite residue disposal area.

Bauxite residue discharged to disposal areas, which could generate environmental pollution issues. Long-term natural restoration may improve the physicochemical properties of the residues, in turn supporting vegetation establishment, and effectively managing pollution. Nevertheless, the effects of short-term human intervention on soil formation in the weathered disposal areas are still relatively unknown.

Evaluation of aggregate formation, stability and pore characteristics of bauxite residue following polymer materials addition.

Bauxite residue has poor physical conditions, which hinders plant growth and causes potential environmental risks. Polymer materials have broad potential applications for holding water and improving soil aggregation. However, no attempt has been made to assess the effects of polymers on physical structure of bauxite residue.

Variation on leaching behavior of caustic compounds in bauxite residue during dealkalization process.

Bauxite residue, a byproduct of alumina manufacture, is a serious environmental pollutant due to its high leaching contents of metals and caustic compounds. Four typical anions of CO, HCO, Al(OH) and OH (represented caustic compounds) and metal ions (As, B, Mo and V) were selected to assess their leaching behavior under dealkalization process with different conditions including liquid/solid ratio (L/S ratio), temperature and leaching time. The results revealed that washing process could remove the soluble composition in bauxite residue effectively.

The dynamic development of bacterial community following long-term weathering of bauxite residue.

Bauxite residue is the industrial waste generated from alumina production and commonly deposited in impoundments. These sites are bare of vegetation due to the extreme high salinity and alkalinity, as well as lack of nutrients. However, long term weathering processes could improve residue properties to support the plant establishment.