Catalytic Asymmetric Deoxygenative Cyclopropanation Reactions by a Chiral Salen-Mo Catalyst.

The catalytic asymmetric cyclopropanation reaction of alkenes with diazo compounds is a direct and powerful method to construct chiral cyclopropanes that are essential to drug discovery. However, diazo compounds are potentially explosive and often require hazardous reagents for their preparation. Here, we report on the use of 1,2-dicarbonyl compounds as safe and readily available surrogates for diazo compounds in the direct catalytic asymmetric deoxygenative cyclopropanation reaction. Enabled by a class of simple and readily accessible chiral salen-Mo catalysts, the reaction proceeded with generally good enantioselectivities and yields toward a wide range of substrates (80 examples). Preliminary mechanistic studies suggested that the proposed µ-oxo bridged dinuclear Mo(III)-species was the catalytically active species. This strategy not only provides a promising route for the synthesis of chiral cyclopropanes but also opens a new window for the potential applications of chiral salen-Mo complexes in asymmetric catalysis.

Molybdenum-Catalyzed Deoxygenative Cyclopropanation of 1,2-Dicarbonyl or Monocarbonyl Compounds.

The transition-metal-catalyzed cyclopropanation of alkenes by the decomposition of diazo compounds is a powerful and straightforward strategy to produce cyclopropanes, but is tempered by the potentially explosive nature of diazo substrates. Herein we report the Mo-catalyzed regiospecific deoxygenative cyclopropanation of readily available and bench-stable 1,2-dicarbonyl compounds, in which one of the two carbonyl groups acts as a carbene equivalent upon deoxygenation and engages in the subsequent cyclopropanation process. The use of a commercially available Mo catalyst afforded an array of valuable cyclopropanes with exclusive regioselectivity in up to 90 % yield. The synthetic utility of this method was further demonstrated by gram-scale syntheses, late-stage functionalization, and the cyclopropanation of a simple monocarbonyl compound. Preliminary mechanistic studies suggest that phosphine (or silane) acts as both a mild reductant and a good oxygen acceptor that efficiently regenerates the catalytically active Mo catalyst through reduction of the Mo-oxo complexes.

Medical record data-enabled machine learning can enhance prediction of left atrial appendage thrombosis in nonvalvular atrial fibrillation.

BACKGROUND: As a major complication of non-valvular atrial fibrillation (NVAF), left atrial appendage (LAA) thrombosis is associated with cerebral ischemic strokes, as well as high morbidity. Due to insufficient incorporation of risk factors, most current scoring methods are limited to the analysis of relationships between clinical characteristics and LAA thrombosis rather than detecting potential risk. Therefore, this study proposes a clinical data-driven machine learning method to predict LAA thrombosis of NVAF. METHODS: Patients with NVAF from January 2014 to June 2022 were enrolled from Southwest Hospital. We selected 40 variables for analysis, including demographic data, medical history records, laboratory results, and the structure of LAA. Three machine learning algorithms were adopted to construct classifiers for the prediction of LAA thrombosis risk. The most important variables related to LAA thrombosis and their influences were recognized by SHapley Addictive exPlanations method. In addition, we compared our model with CHADS2 and CHADS2-VASc scoring methods. RESULTS: A total of 713 participants were recruited, including 127 patients with LAA thrombosis and 586 patients with no obvious thrombosis. The consensus models based on Random Forest and eXtreme Gradient Boosting LAA thrombosis prediction (RXTP) achieved the best accuracy of 0.865, significantly outperforming CHADS2 score and CHA2DS2-VASc score (0.757 and 0.754, respectively). The SHAP results showed that B-type natriuretic peptide, left atrial appendage width, C-reactive protein, Fibrinogen and estimated glomerular filtration rate are closely related to the risk of LAA thrombosis in nonvalvular atrial fibrillation. CONCLUSIONS: The RXTP-NVAF model is the most effective model with the greatest ROC value and recall rate. The summarized risk factors obtained from SHAP enable the optimization of the treatment strategy, thereby preventing thromboembolism events and the occurrence of cardiogenic ischemic stroke.

[Performance Evaluation of a Pilot-scale Microbubble-aerated Biofilm Reactor].

A pilot-scale microbubble-aerated biofilm reactor was operated to treat campus domestic wastewater and its performance was evaluated and compared with conventional biological treatment processes. The results indicated that when the raw campus domestic wastewater was treated in the pilot system, the average COD removal efficiency and loading rate removed were 57.0% and 2.68 kg·(m3·d)-1; the average ammonia nitrogen removal efficiency and loading rate removed were 17.4% and 0.17 kg·(m3·d)-1; the average total nitrogen (TN) removal efficiency and loading rate removed were 15.8% and 0.21 kg·(m3·d)-1; and the average oxygen utilization efficiency reached 100%. When the effluent of biological contact oxidation tank with poor biodegradability was treated in the pilot system, the average COD removal efficiency and loading rate removed were 46.0% and 1.53 kg·(m3·d)-1; the average ammonia nitrogen removal efficiency and loading rate removed were 17.1% and 0.32 kg·(m3·d)-1; the average total nitrogen (TN) removal efficiency and loading rate removed were 14.1% and 0.28 kg·(m3·d)-1; and the average oxygen utilization efficiency was higher than 50%. Furthermore, the contaminant removal performance of the pilot system was much more efficient than conventional biological contact oxidation tank and biological aeration filter tank with the same influent quality, since oxygen transfer and oxygen utilization could be enhanced by microbubble aeration.

[Current status and development of monitoring on adverse reaction of traditional Chinese medicine in China].

With the wide usage of traditional Chinese medicine (TCM) and the diversity of its dosage-forms, the reports about adverse reaction (ADR) caused by TCM were gradually increased. As the cradle of TCM with tremendous manufacturing enterprise engaged for this purpose, to establish and perfect the TCM ADR monitoring is the problem that TCM industry should face to. In this paper, the key point of TCM ADR monitoring was made clear by analysing the current situation and the problems presented in TCM ADR monitoring in China, and indicated that the nowday developing goals of TCM ADR monitoring are to establish and perfect the technologic system for TCM ADR monitoring, strengthen the related basic research and enhance international communication and cooperation in this field.

[Effect of Membrane Wettability on Membrane Fouling and Chemical Durability of SPG Membranes].

Shirasu porous glass (SPG) membranes have been applied for microbubble aeration in aerobic wastewater treatment. In the present study, both hydrophilic and hydrophobic SPG membranes were used in a microbubble-aerated biofilm reactor with online chemical cleaning, and their membrane fouling and chemical durability were determined to be strongly dependent on the membrane wettability. The fouling layer formed on the surface of both membranes was confirmed to be mainly organic fouling, and the hydrophobic membrane showed a relatively stronger resistance to the organic fouling. The severe chemical corrosion of the hydrophilic membrane was observed due to exposure to the alkaline sodium hypochlorite solution used for chemical cleaning, which resulted in significant increases in the median pore diameter and the porosity. On the other hand, the pore structure of the hydrophobic membrane changed slightly when exposed to the alkaline sodium hypochlorite solution, suggesting its strong alkali-resistance due to the non-wetting surface. However, the surface hydrophobic groups of hydrophobic membrane could be oxidized by sodium hypochlorite solution, resulting in more wettable membrane surface. The hydrophobic membrane also showed better performance in the respects of oxygen transfer, contaminant removal and energy-saving. Therefore, the hydrophobic membrane seemed more appropriate to be applied for microbubble aeration in aerobic wastewater treatment process.