Divalent Silicon-Assisted Activation of Dihydrogen in a Bis(N-heterocyclic silylene)xanthene Nickel(0) Complex for Efficient Catalytic Hydrogenation of Olefins

The first chelating bis­(N-heterocyclic silylene)­xanthene ligand [Si^II(Xant)­Si^II] as well as its Ni complexes [Si^II(Xant)­Si^II]­Ni­(η²-1,3-cod) and [Si^II(Xant)­Si^II]­Ni­(PMe₃)₂ were synthesized and fully characterized. Exposing [Si^II(Xant)­Si^II]­Ni­(η²-1,3-cod) to 1 bar H₂ at room temperature quantitatively generated an unexpected dinuclear hydrido Ni complex with a four-membered planar Ni₂Si₂ core. Exchange of the 1,3-COD ligand by PMe₃ led to [Si^II(Xant)­Si^II]­Ni­(PMe₃)₂, which could activate H₂ reversibly to afford the first Si^II-stabilized mononuclear dihydrido Ni complex characterized by multinuclear NMR and single-crystal X-ray diffraction analysis. [Si^II(Xant)­Si^II]­Ni­(η²-1,3-cod) is a strikingly efficient precatalyst for homogeneous hydrogenation of olefins with a wide substrate scope under 1 bar H₂ pressure at room temperature. DFT calculations reveal a novel mode of H₂ activation, in which the Si^II atoms of the [Si^II(Xant)­Si^II] ligand are involved in the key step of H₂ cleavage and hydrogen transfer to the olefin

Synthesis and Reactivity of the CO₂ Adducts of Amine/Bis(2,4,6-tris(trifluoromethyl)phenyl)borane Pairs

Frustrated Lewis pairs (FLPs) comprised of bis­(2,4,6-tris­(trifluoromethyl)­phenyl)­borane (<b>1</b>) and a secondary amine (such as HN<i>i</i>Pr₂ or HNEt₂) readily react with CO₂ at room temperature to afford ammonium carbamatoborate salts <b>2</b>. When the reaction was carried out at 80 °C, carbamate boryl esters <b>3</b> were obtained with release of 1 equiv of H₂. The <i>i</i>Pr-substituted carbamate boryl ester <b>3a</b> can function as an intramolecular FLP to activate H₂, affording ammonium borylformate salt <b>4a</b> and formamide adduct <b>5a</b>. Two reaction pathways leading to the formation of <b>4a</b> and <b>5a</b> are proposed

DataSheet_1_Derivation of predicted no-effect concentrations for thirty-five pharmaceuticals and personal care products in freshwater ecosystem.xlsx

Pharmaceuticals and personal care products (PPCPs) are contaminants of emerging concern. PPCPs have been detected in various environmental matrices, posing potential threat to human health and environment quality. Thus far, there are no water quality guidelines (WQGs) established for PPCPs for the protection of freshwater organisms and ecosystems. In this study, we used the species sensitivity distribution (SSD) and assessment factor (AF) approaches to derive the 5% hazardous concentrations (HC5) of 35 selected PPCPs using acute and chronic toxicity data. The predicted no-effect concentrations (PNECs) and the acute-to-chronic ratios (ACRs) of chemicals were inherently computed to support the derivation of WQGs and for ecological risk assessment. Among these, endocrine-disrupting chemicals and antipsychotics were shown to pose a greater threat to the freshwater environment and organisms. The highest PNEC was recorded for chloramphenicol (3,620 μg/L) and the lowest for fluoxetine (0.0000291 μg/L), which could have significant ecological risks. In addition, the commonly used default ACRs do not seem to provide adequate support for the prediction of chronic toxicity thresholds and WQGs, as the highest ACRs of these drugs reached 39,100 (e.g., chloramphenicol). The findings of this study provide critical scientific information regarding the development of WQGs for environmental management and the risk control of PPCPs.</p

DataSheet_1_Temperature-dependent effects of neonicotinoids on the embryonic development of zebrafish (Danio rerio).docx

The agricultural use of neonicotinoids is increasing worldwide and poses a threat to non-target organisms. The existing toxicity data of neonicotinoids that is mainly focused on widely used neonicotinoids ignores the influence of environmental factors, like temperature, related to climate changes, etc. To fill this data gap, the present study assessed the temperature-dependent toxicity of six neonicotinoids at four temperatures. Briefly, a fish embryo toxicity test was performed at the following temperatures—20, 23, 28, and 33°C—on zebrafish embryos to evaluate the lethal and sublethal effects of these toxicants. At 28°C, the lethal toxicity (LC50) values for these toxicants were cycloxaprid—3.36 mg/L, nitenpyram—7.08 mg/L, paichongding—17.2 mg/L, imidaclothiz—738.6 mg/L, dinotefuran—2,096 mg/L, and thiamethoxam—4,293 mg/L, respectively. Among the sublethal effects, the enzymatic activities changed significantly in neonicotinoid treatments, which revealed oxidative stress, metabolic disorders, and neurotoxicity. Particularly, acetylcholinesterase inhibition and glutathione S-transferase activation showed a significant dose–response relationship. However, cycloxaprid, nitenpyram, and paichongding were found to be more potent compared with imidaclothiz and thiamethoxam. The influence of temperature on these neonicotinoids demonstrated an inverted V-shaped relationship, in which toxicity decreased with the increase of temperature and then increased with the increase of temperature after exceeding the optimum temperature. This study provides a reference for the multiscale effects and potential mechanisms of neonicotinoids. Temperature-dependent toxicity is of great significance for future toxicity testing and risk assessment of chemicals in the face of global climate changes.</p

Image1_Lycium barbarum polysaccharide alleviates dextran sodium sulfate-induced inflammatory bowel disease by regulating M1/M2 macrophage polarization via the STAT1 and STAT6 pathways.pdf

Disruption of colonic homeostasis caused by aberrant M1/M2 macrophage polarization contributes to the development of inflammatory bowel disease (IBD). Lycium barbarum polysaccharide (LBP) is the primary active constituent of traditional Chinese herbal Lycium barbarum L., which has been widely demonstrated to have important functions in regulating immune activity and anti-inflammatory. Thus, LBP may protect against IBD. To test this hypothesis, the DSS-induced colitis model was established in mice, then the mice were treated with LBP. The results indicated that LBP attenuated the weight loss, colon shortening, disease activity index (DAI), and histopathological scores of colon tissues in colitis mice, suggesting that LBP could protect against IBD. Besides, LBP decreased the number of M1 macrophages and the protein level of Nitric oxide synthase 2(NOS2) as a marker of M1 macrophages and enhanced the number of M2 macrophages and the protein level of Arginase 1(Arg-1) as a marker of M2 macrophages in colon tissues from mice with colitis, suggesting that LBP may protect against IBD by regulating macrophage polarization. Next, the mechanistic studies in RAW264.7 cells showed that LBP inhibited M1-like phenotype by inhibiting the phosphorylation of STAT1, and promoted M2-like phenotype by promoting the phosphorylation of STAT6. Finally, immunofluorescence double-staining results of colon tissues showed that LBP regulated STAT1 and STAT6 pathways in vivo. The results in the study demonstrated that LBP could protect against IBD by regulating macrophage polarization through the STAT1 and STAT6 pathways.</p

Clinical features associated with IL-17A and IL-17F gene polymorphisms.

<p>Clinical features associated with IL-17A and IL-17F gene polymorphisms.</p

Evaluation of Sulfadiazine Degradation in Three Newly Isolated Pure Bacterial Cultures

<div><p>This study is aimed to assess the biodegradation of sulfadiazine (SDZ) and characterization of heavy metal resistance in three pure bacterial cultures and also their chemotactic response towards 2-aminopyrimidine. The bacterial cultures were isolated from pig manure, activated sludge and sediment samples, by enrichment technique on SDZ (6 mg L^-1). Based on the 16S rRNA gene sequence analysis, the microorganisms were identified within the genera of <i>Paracoccus</i>, <i>Methylobacterium</i> and <i>Kribbella</i>, which were further designated as SDZ-PM2-BSH30, SDZ-W2-SJ40 and SDZ-3S-SCL47. The three identified pure bacterial strains degraded up to 50.0, 55.2 and 60.0% of SDZ (5 mg L^-1), respectively within 290 h. On the basis of quadrupole time-of-flight mass spectrometry and high performance liquid chromatography, 2-aminopyrimidine and 4-hydroxy-2-aminopyrimidine were identified as the main intermediates of SDZ biodegradation. These bacteria were also able to degrade the metabolite, 2-aminopyrimidine, of the SDZ. Furthermore, SDZ-PM2-BSH30, SDZ-W2-SJ40 and SDZ-3S-SCL47 also showed resistance to various heavy metals like copper, cadmium, chromium, cobalt, lead, nickel and zinc. Additionally, all three bacteria exhibited positive chemotaxis towards 2-aminopyrimidine based on the drop plate method and capillary assay. The results of this study advanced our understanding about the microbial degradation of SDZ, which would be useful towards the future SDZ removal in the environment.</p></div

Allele frequencies of eight SNPs in the IL-17A and IL-17F genes.

†<p>controls = 501, missing = 1;</p>‡<p>controls = 499, missing = 3.</p>a<p><i>P</i> = 0.0311 after correcting the <i>P</i>-value for multiple testing with the Haploview program using 10,000 permutations.</p

Haplotype frequencies in breast cancer patients and healthy controls.

<p>The haplotypes contain the following SNPs in the order listed: IL-17A: rs2275913, rs3819025 and rs3748067; IL-17F: rs763780, rs7771511, rs12203582, rs9382084 and rs1266828. The haplotypes occurred with a frequency of = 10% in the case-control population.</p>a<p><i>P</i> = 0.0471 after correcting the <i>P</i>-value for multiple testing with the Haploview program using 10,000 permutations.</p

Phylogenetic relationships established by the maximum-likelihood method (using MEGA6 software) based on 16S rRNA gene sequences of isolated bacterial strains (SDZ-PM2-BSH30, SDZ-W2-SJ40, and SDZ-3S-SCL47).

<p>Scale bar, no. of nucleotide changes/sequence position. The number at nodes shows the bootstrap values obtained with 1,000 resampling analyses.</p