Enhanced Immobilization of Cadmium and Lead in Contaminated Soil using Calcium Alginate-Modified HAP Biochar: Improvements in Soil Health and Microbial Diversity.

A novel adsorbent, calcium alginate-modified HAP (Hydroxyapatite)-wood ear mushroom sticks biochar (CA-HAPMB), was synthesized to enhance the immobilization of Cd and Pb in soil. Over 150 days, applying CA-HAPMB at concentrations of 0%-3% in contaminated soils from Chenzhou City in Hunan Province (CZ) and Shenyang City in Liaoning Province (SY) resulted in decreased effective concentrations of Cd and Pb. Specifically, in CZ soil, Cd and Pb decreased by 30.9%-69.3% and 31.9%-78.6%, respectively, while in SY soil, they decreased by 27.5%-53.7% and 26.4%-62.3%, respectively. Characterization results, obtained after separating CA-HAPMB from the soil, indicate that complexation, co-precipitation, and ion exchange play crucial roles in the efficient immobilization of Cd and Pb by CA-HAPMB. Additionally, adjusting the amount of CA-HAPMB added allows modulation of soil pH, leading to increased soil organic matter and nutrient content. Following treatment with CA-HAPMB for immobilizing Cd and Pb, soil bacteria abundance and diversity increased, further promoting heavy-metal immobilization.

Exploration the interaction of cadmium and copper toxic effects in pakchoi (Brassica chinensis L) roots through combinatorial transcriptomic and weighted gene co-expression network analysis.

The interaction between cadmium(Cd) and copper(Cu) during combined pollution can lead to more complex toxic effects on humans and plants.However, there is still a lack of sufficient understanding regarding the types of interactions at the plant molecular level and the response strategies of plants to combined pollution. To assess this, we investigated the phenotypic and transcriptomic patterns of pakchoi (Brassica chinensis L) roots in response to individual and combined pollution of Cd and Cu. The results showed that compared to single addition, the translocation factor of heavy metals in roots significantly decreased (p < 0.05) under the combined addition, resulting in higher accumulation of Cd and Cu in the roots. Transcriptomic analysis of pakchoi roots revealed that compared to single pollution, there were 312 and 1926 differentially expressed genes (DEGs) specifically regulated in the Cd2Cu20 and Cd2Cu100 combined treatments, respectively. By comparing the expression of these DEGs among different treatments, we found that the combined pollution of Cd and Cu mainly affected the transcriptome of the roots in an antagonistic manner. Enrichment analysis indicated that pakchoi roots upregulated the expression of genes involved in glucosetransferase activity, phospholipid homeostasis, proton transport, and the biosynthesis of phenylpropanoids and flavonoids to resist Cd and Cu combined pollution. Using weighted gene co-expression network analysis (WGCNA), we identified hub genes related to the accumulation of Cd and Cu in the roots, which mainly belonged to the LBD, thaumatin-like protein, ERF, MYB, WRKY, and TCP transcription factor families. This may reflect a transcription factor-driven trade-off strategy between heavy metal accumulation and growth in pakchoi roots. Additionally, compared to single metal pollution, the expression of genes related to Nramp, cation/H+ antiporters, and some belonging to the ABC transporter family in the pakchoi roots was significantly upregulated under combined pollution. This could lead to increased accumulation of Cd and Cu in the roots. These findings provide new insights into the interactions and toxic mechanisms of multiple metal combined pollution at the molecular level in plants.

Characteristics and health risks of population exposure to phthalates via the use of face towels.

The production of face towels is growing at an annual rate of about 4% in China, reaching 1.13 million tons by 2021. Phthalates (PAEs) are widely used in textiles, and face towels, as an important household textile, may expose people to PAEs via the skin, further leading to health risks. We collected new face towels and analyzed the distribution characterization of PAEs in them. The changes of PAEs were explored in a face towel use experiment and a simulated laundry experiment. Based on the use of face towels by 24 volunteers, we calculated the estimated daily intake (EDI) and comprehensively assessed the hazard quotient (HQ), hazard index (HI), and dermal cancer risk (DCR) of PAEs exposure in the population. PAEs were present in new face towels at total concentrations of

Nickel-Catalyzed Sulfonylation of Aryl Bromides Enabled by Potassium Metabisulfite as a Uniquely Effective SO2 Surrogate.

The development and mechanistic investigation of a nickel-catalyzed sulfonylation of aryl bromides is disclosed. The reaction proceeds in good yields for a variety of substrates and utilizes an inexpensive, stench-free, inorganic sulfur salt (K2 S2 O5 ) as a uniquely effective SO2 surrogate. The active oxidative addition complex was synthesized, isolated, and fully characterized by a combination of NMR spectroscopy and X-ray crystallography analysis. The use of the isolated oxidative addition complex in both stoichiometric and catalytic reactions revealed that SO2 insertion occurs via dissolved SO2 , likely released upon thermal decomposition of K2 S2 O5 . Key to the success of the reaction is the role of K2 S2 O5 as a reservoir of SO2 that is slowly released, thus preventing catalyst poisoning.

Late-Stage Modification of Oligopeptides by Nickel-Catalyzed Stereoselective Radical Addition to Dehydroalanine.

Radical addition to dehydroalanine (Dha) represents an appealing, modular strategy to access non-canonical peptide analogues for drug discovery. Prior studies on radical addition to the Dha residue of peptides and proteins have demonstrated outstanding functional group compatibility, but the lack of stereoselectivity has limited the synthetic utility of this approach. Herein, we address this challenge by employing chiral nickel catalysts to control the stereoselectivity of radical addition to Dha on oligopeptides. The conditions accommodate a variety of primary and secondary electrophiles to introduce polyethylene glycol, biotin, halo-tag, and hydrophobic and hydrophilic side chains to the peptide. The reaction features catalyst control to largely override substrate-based control of stereochemical outcome for modification of short peptides. We anticipate that the discovery of chiral nickel complexes that confer catalyst control will allow rapid, late-stage modification of peptides featuring nonnatural sidechains.

Inhalation Bioaccessibility and Risk Assessment of Metals in PM2.5 Based on a Multiple-Path Particle Dosimetry Model in the Smelting District of Northeast China.

PM2.5 can deposit and partially dissolve in the pulmonary region. In order to be consistent with the reality of the pulmonary region and avoid overestimating the inhalation human health risk, the bioaccessibility of PM2.5 heavy metals and the deposition fraction (DF) urgently needs to be considered. This paper simulates the bioaccessibility of PM2.5 heavy metals in acidic intracellular and neutral extracellular deposition environments by simulating lung fluid. The multipath particle dosimetry model was used to simulate DF of PM2.5. According to the exposure assessment method of the U.S. Environmental Protection Agency, the inhalation exposure dose threshold was calculated, and the human health risk with different inhalation exposure doses was compared. The bioaccessibility of heavy metals is 12.1−36.2%. The total DF of PM2.5 in adults was higher than that in children, and children were higher than adults in the pulmonary region, and gradually decreased with age. The inhalation exposure dose threshold is 0.04−14.2 mg·kg−1·day−1 for the non-carcinogenic exposure dose and 0.007−0.043 mg·kg−1·day−1 for the carcinogenic exposure dose. Cd and Pb in PM2.5 in the study area have a non-carcinogenic risk to human health (hazard index < 1), and Cd has no or a potential carcinogenic risk to human health. A revised inhalation health risk assessment may avoid overestimation.

Benzylic Photobromination for the Synthesis of Belzutifan: Elucidation of Reaction Mechanisms Using In Situ LED-NMR.

A detailed mechanistic understanding of a benzylic photobromination en route to belzutifan (MK-6482, a small molecule for the treatment of renal cell carcinoma associated with von Hippel-Lindau syndrome) has been achieved using in situ LED-NMR spectroscopy in conjunction with kinetic analysis. Two distinct mechanisms of overbromination, namely, the ionic and radical pathways, have been revealed by this study. The behavior of the major reaction species, including reactants, intermediates, products, and side products, has been elucidated. Comprehensive understanding of both pathways informed and enabled mitigation of a major process risk: a sudden product decomposition. Detailed knowledge of the processes occurring during the reaction and their potential liabilities enabled the development of a robust photochemical continuous flow process implemented for commercial manufacturing.

A multifunctional catalyst that stereoselectively assembles prodrugs.

The catalytic stereoselective synthesis of compounds with chiral phosphorus centers remains an unsolved problem. State-of-the-art methods rely on resolution or stoichiometric chiral auxiliaries. Phosphoramidate prodrugs are a critical component of pronucleotide (ProTide) therapies used in the treatment of viral disease and cancer. Here we describe the development of a catalytic stereoselective method for the installation of phosphorus-stereogenic phosphoramidates to nucleosides through a dynamic stereoselective process. Detailed mechanistic studies and computational modeling led to the rational design of a multifunctional catalyst that enables stereoselectivity as high as 99:1.