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.

Transaminase-Catalyzed Synthesis of ß-Branched Noncanonical Amino Acids Driven by a Lysine Amine Donor.

Transaminases are choice biocatalysts for the synthesis of chiral primary amines, including amino acids bearing contiguous stereocenters. In this study, we employ lysine as a "smart" amine donor in transaminase-catalyzed dynamic kinetic resolution reactions to access ß-branched noncanonical arylalanines. Our mechanistic investigation demonstrates that, upon transamination, the lysine-derived ketone byproduct readily cyclizes to a six-membered imine, driving the equilibrium in the desired direction and thus alleviating the need to load superstoichiometric quantities of the amine donor or deploy a multienzyme cascade. Lysine also shows good overall compatibility with a panel of wild-type transaminases, a promising hint of its application as a smart donor more broadly. Indeed, by this approach, we furnished a broad scope of ß-branched arylalanines, including some bearing hitherto intractable cyclopropyl and isopropyl substituents, with high yields and excellent selectivities.

Dynamic sampling in autonomous process optimization.

Autonomous process optimization (APO) is a technology that has recently found utility in a multitude of process optimization challenges. In contrast to most APO examples in microflow reactor systems, we recently presented a system capable of optimization in high-throughput batch reactor systems. The drawback of APO in a high-throughput batch reactor system is the reliance on reaction sampling at a predetermined static timepoint rather than a dynamic endpoint. Static timepoint sampling can lead to the inconsistent capture of the process performance under each process parameter permutation. This is important because critical process behaviors such as rate acceleration accompanied by decomposition could be missed entirely. To address this drawback, we implemented a dynamic reaction endpoint determination strategy to capture the product purity once the process stream stabilized. We accomplished this through the incorporation of a real-time plateau detection algorithm into the APO workflow to measure and report the product purity at the dynamically determined reaction endpoint. We then applied this strategy to the autonomous optimization of a photobromination reaction towards the synthesis of a pharmaceutically relevant intermediate. In doing so, we not only uncovered process conditions to access the desired monohalogenation product in 85 UPLC area % purity with minimal decomposition risk, but also measured the effect of each parameter on the process performance. Our results highlight the advantage of incorporating dynamic sampling in APO workflows to drive optimization toward a stable and high-performing process.

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.

Filtration of polystyrene nanoplastics with different functional groups by natural mineral materials: Performance and mechanisms.

Optimizing nanoplastics (NPs) removal performance of rapid sand filter (RSF) in water treatment plants is significant for NP pollution prevention and remediation. This study investigated the application prospect of natural granular manganese sand, zeolite and limestone in RSF for NP removal through column experiments. Pristine, amino-modified, and carboxyl-modified polystyrene NPs (100 nm) were selected as experimental subjects. Quartz sand filter showed negligible NP removal, zeolite and manganese sand showed no obvious optimization on NP filtration. Limestone amended RSF significantly enhanced the removal of three NPs, the removal efficiency increased with decreasing size and increasing limestone grains dosage. The excellent performance of limestone was attributed to its special physicochemical properties in terms of synthetical action of electrostatic interaction, cationic bridging and especially the surface roughness morphology, and the mechanisms overcame the influence of functional groups of NPs. The results indicate the prospective applications of granular limestone in RSF for NP filtration.

Overcoming Product Inhibition in a Nucleophilic Aromatic Substitution Reaction.

The development of a nucleophilic aromatic substitution (SNAr) reaction for the synthesis of belzutifan and related analogues is disclosed. This classical transformation suffered from reaction stalling, despite prolonged reaction times. Through experimental and mechanistic studies, product inhibition was revealed and rationalized. Herein, we describe our efforts to overcome this synthetic challenge and demonstrate the importance of the judicious choice of the solvent to achieve reactivity.

Distribution and major driving elements of antibiotic resistance genes in the soil-vegetable system under microplastic stress.

Microplastics (MPs) and antibiotic resistance genes (ARGs) are both enriched in soil-vegetable systems as a consequence of the prolonged use of agricultural mulches. MPs can form unique bacterial communities and provide potential hosts for ARGs. Therefore, MPs stress may promote the spread of ARGs from soil to crops. Increasing ARGs pollution in soil-vegetable system. In our research, we investigated the distribution and major driving elements of antibiotic resistance genes in the soil-vegetable system under microplastic stress. The results showed that MPs treatment decreased the relative abundance of ARGs in non-rhizosphere soil. High concentrations of MPs promoted the enrichment of tetracycline antibiotic resistance genes in rhizosphere soil. MPs treatment promoted the enrichment of ARGs and mobile genetic elements (MGEs) in lettuce tissues, and the overall abundance of ARGs in root after 0.5 %, 1 %, and 2 % (w/w, dry weight) polyethylene (PE) administration was considerably higher compared to that in the untreated group (p < 0.05). At the same time, high PE concentrations promoted the spread of sulfa ARGs from root to leaf. MPs also impacted the bacterial communities in the soil-plant system, and the changes in ARGs as well as MGEs in each part of the soil-vegetable system were significantly correlated with the bacterial diversity index (p < 0.05). Correlation analysis and network analysis showed that bacterial communities and MGEs were the main drivers of ARGs variation in soil-lettuce systems.

Comprehensive assessment of phthalates in indoor dust across China between 2007 and 2019: Benefits from regulatory restrictions.

China is the largest producer and consumer of phthalates in the world. However, it remains unclear whether China's phthalate restrictions have alleviated indoor phthalate pollution. We extracted the concentrations of dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), benzyl butyl phthalate (BBP), and bis(2-ethylhexyl) phthalate (DEHP) in indoor dust at 2762 sites throughout China between 2007 and 2019 from the published literature. Based on these data, we investigated the effects of phthalate restrictions and environmental factors on the temporal-spatial distribution and sources of phthalates and estimated human exposure and risk of phthalates. The results revealed that the mean concentrations of phthalates in indoor dust throughout China decreased in the following order: DEHP > DBP > DIBP > DMP > DEP > BBP. The concentrations of six phthalates were generally higher in northern and central-western China than in southern regions. BBP and DEHP concentrations decreased by 73.5% and 17.9%, respectively, from 2007 to 2019. Sunshine was a critical environmental factor in reducing phthalate levels in indoor dust. Polyvinyl chloride materials, personal care products, building materials, and furniture were the primary sources of phthalates in indoor dust. The phthalates in indoor dust posed the most significant threat to children and older adults. This study provides a picture of phthalate pollution, thus supporting timely and effective policies and legislation.

Estimate of the maximum amount of dust adhering to skin and the upper limit of dust-skin adherence factor for young adults: An example from Changchun, China.

Contaminants present in dust adhering to the skin can pose a significant risk to human health through dermal absorption and hand-to-mouth contact. The adhesion capacity of dust differs significantly from that of soil due to its physicochemical properties. Therefore, applying the raw soil exposure parameters to estimate the health risks associated with dermal exposure to dust may lead to erroneous conclusions. In this study, we quantified the maximum amount of dust that adhered to the skin (MADmax) and the upper limit of dust-skin adherence factor (DSAFmax) in 26 adults using element markers as a proxy for dust. The volunteers were exposed to dust and rinse water samples were collected from their hands, forearms, lower legs, and feet. We analyzed both the raw dust samples and the rinse water samples for 11 element markers, including Be, V, Cr, Mn, Co, Ni, Cu, Zn, Se, Ba, and Pb. The results showed that the MADmax of indoor dust and outdoor dust increased by 0.08-0.62 mg and 0.33-0.56 mg following a 1 cm2 increase in skin surface area, respectively. Based on best dust element markers, the body part-weighted dust-skin adherences (WDSAFmaxs) of indoor dust and outdoor dust were 0.35 and 0.64 mg/cm2, respectively. A smaller particle size and higher moisture content resulted in a larger DSAFmax. Only when indoor dust concentrations exceed 24.2 mg/m3 or outdoor dust concentrations exceed 44.3 mg/m3, can the WDSAFmax be applied directly in the health risk assessment of dermal exposure to dust. The method from this study can be re-applied in different regions, and the adherence data can help to improve future studies on the health effects of dermal exposure to dust.

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.

Bioaccumulation of organophosphorus flame retardants in marine organisms in Liaodong Bay and their potential ecological risks based on species sensitivity distribution.

Although organophosphorus flame retardants (OPFRs) in aquatic environments have received increasing concern, little information is available on their bioaccumulation and trophic transfer in marine food webs. Consequently, the risks of OPFRs to marine ecosystems are unknown. In this study, seven OPFR compounds in marine biological samples collected from Liaodong Bay, Bohai Sea, were analyzed to evaluate their level and biological amplification effect in the marine food web. The total OPFRs of marine organisms in Liaodong Bay ranged from 2.60 to 776 ng/g ww, and lipids were critical factors affecting the concentration of OPFRs in marine species. Tris (2-ethylhexyl) phosphate (TEHP) and tris(1-chloro-2-propyl) phosphate (TCIPP) were the OPFRs most frequently detected in marine species. Still, tris(2-chloroethyl) phosphate (TCEP) was dominant in most marine species (16/24), and the content of chlorinated OPFRs was highest. At the same time, alkyl OPFRs and aryl OPFRs accounted for the same proportion. No correlation between OPFR concentration and the trophic level was observed in marine organisms from Liaodong Bay. It was shown in the results of the species sensitivity distribution that TCIPP in Chinese seawater does not pose a potential ecological risk to marine species. However, much work remains to be done on accumulating information and the ecological risks of OPFRs in different marine food webs.

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.

Impact of environmental factors and bacterial interactions on dust mite allergens in different indoor dust.

Indoor dust is the main carrier of indoor pollutants, especially dust mite allergens and bacteria, they can trigger asthma, rhinitis, eczema and other allergic diseases. However, the interactions between dust mite allergens and bacterial communities in different types of indoor dust are not clear. The study focused on particulate and flocculent fibrous dust, explored the concentrations of Der p 1 (Dermatophagoides pteronyssinus) and Der f 1 (D. farinae) in 46 households in Changchun and their environmental influences, characterized the bacterial communities by high-throughput sequencing, and the interactions between Der p 1, Der f 1 and bacterial communities were explored. The results showed that Der p 1 and Der f 1 tended to accumulate more in flocculent fibrous dust, and Der p 1 predominated in the indoor dust samples. The floor height, years of housing occupancy and the living areas all affected the concentrations of dust mite allergens. In bacterial community, Proteobacteria, Firmicutes and Actinobacteria were leading phyla in the two types of dust. Kocuria, Blastococcus and Massilia were dominating genera in particulate dust and Acinetobacter, Lactobacillus, Corynebacterium_1 were dominating genera in flocculent fibrous dust. The overall diversity and species richness of bacteria in particulate dust were significantly higher than those in flocculent dust (p < 0.001). The living area was an important environmental factor affecting the bacterial community in flocculent fibrous dust (p < 0.01). The interaction between the relative abundance of Proteobacteria, Firmicutes and Actinobacteria and dust mite allergen concentrations significantly differed between the two dust types, indicating that bacteria could be used both as food and to establish symbiotic relationships with household dust mites (HDMs) hosts and provide nutrition.

The effect of carbonization temperature on the capacity and mechanisms of Cd(II)-Pb(II) mix-ions adsorption by wood ear mushroom sticks derived biochar.

Heavy metals often coexist in contaminated environmental media, and competition between heavy metals for adsorption sites influences the absorption capacity of biochar. In this study, the adsorption mechanism of pyrolytically modified wood ear mushroom sticks (250, 450, and 650 °C) as a new bio-adsorbent for single-ion and mixed-ion solutions Cd2+ and Pb2+ Biochar adsorption experiments showed that the adsorption abilities of Cd2+ and Pb2+ increased with increasing WMBC (wood ear mushroom sticks biochar) pyrolysis temperature. According to the Langmuir model, the maximum adsorption capacity of Cd2+ and Pb2+increased with higher pyrolysis temperature, being 29.84, 39.08, 46.16 mg·g-1and 124.3, 186.8, 234.2 mg·g-1, respectively for three different pyrolysis temperatures 250, 450, and 650 °C. WMBC exhibited a stronger adsorption ability for Pb2+ than for Cd2+. Competition between the two heavy metals severely inhibited the adsorption of Cd2+. Based on X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infrared spectroscopy (FTIR) analyses, the dominant interaction mechanisms were determined to be complexation, ion exchange, precipitation, and C-π interaction. The results suggest WMBC shows promise as a novel, cheap, and effective adsorbent that can be used to remove both Cd2+ and Pb2+ pollutants from environmental media.

Highly Enantioselective Rhodium-Catalyzed Transfer Hydrogenation of Tetrasubstituted Olefins: Application toward the Synthesis of GPR40 Agonist MK-2305.

A highly efficient enantioselective synthesis for the potent G-protein-coupled receptor 40 agonist MK-2305 was developed. The key tetrasubstituted olefin was prepared via a stereoselective Mukaiyama aldol reaction/elimination sequence. The highly enantioselective rhodium-catalyzed transfer hydrogenation of the tetrasubstituted olefin afforded the target compound MK-2305 in excellent optical and chemical purity. The key asymmetric transfer hydrogenation proceeds in excellent yields and enantioselectivities for a variety of substrates. The superior reactivity of the tethered catalysts was revealed by NMR studies.

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.

Organocatalytic Conversion of Nucleosides to Furanoid Glycals.

A class of organocatalysts that are highly active for the conversion of 2'-deoxynucleosides to furanoid glycals have been discovered. These phosphorimides, (Ph2PS)2NH and (Ph2PSe)2NH, were shown to effectively mediate persilylation of 2'-deoxynucleosides allowing the elimination of the nucleobase giving the corresponding glycal. These mild conditions were demonstrated in the syntheses of glycals with various substitution patterns while minimizing the formation of undesired byproducts and expanding the scope of this methodology.