Edge-sharing bi-octahedral diruthenium(IV,IV) compounds containing Ru-Ru bonds chelated and bridged by two carbonate and two oxo groups.

From paddle-wheel starting material Na3Ru2(CO3)4·6H2O, a family of edge-sharing bi-octahedral (ESBO) diruthenium(IV,IV) compounds formulated as Ru2O2(CO3)2(H2O)2L2·nH2O [L = piperazine (1) or 2-methylpiperazine (2), n = 4, and L = 2,2-dimethylpiperazine (3), n = 12] and Ru2O2(CO3)2(OH)4{M(H2O)4}2·nH2O [M = Mg (4), n = 4, and Ni (5), n = 2] were prepared and structurally characterized. The Ru28+ dimer is chelated and bridged by two CO32- and two µ-O in a trans manner, and the Ru-Ru distances fall in the range 2.3808(6)-2.4001(4) Å. Compound 2 shows the shortest Ru-Ru distance for all known ESBO Ru2 compounds reported thus far. Increasing -CH3 groups of terminal piperazine ligands coordinated to the Ru(µ-O)2(µ-O3C)2Ru core, and according to Raman spectra experiments combined with theoretical calculations, the intense bands of compounds 1-3 appearing at ∼360 cm-1 can be assigned to the stretching of Ru-Ru bonds.

Multicomponent Dearomative Difluoroalkylation of Isoquinolines with Difluorinated Silyl Enol Ethers: Divergent Synthesis of gem-Difluorinated Heterocycles.

A multicomponent dearomative difluoroalkylation of isoquinolines has been developed with difluorinated silyl enol ethers serving as poor nucleophiles without an additional transition-metal or organic catalyst. The sequential oxidative rearomatization under different alkaline conditions provides a controllable formal C-H difluoroalkylation and difluoromethylation method for isoquinolines without peroxide or metal oxidant. A series of isoquinolines including a pharmaceutical, phenanthridine, quinolines, and difluorinated silyl enol ethers were suitable substrates to construct gem-difluorinated heterocycles. The inexpensive starting materials, mild reaction conditions, and simple operation also show practical and environmentally benign advantages.

Dynamic PET image reconstruction incorporating a median nonlocal means kernel method.

In dynamic positron emission tomography (PET) imaging, the reconstructed image of a single frame often exhibits high noise due to limited counting statistics of projection data. This study proposed a median nonlocal means (MNLM)-based kernel method for dynamic PET image reconstruction. The kernel matrix is derived from median nonlocal means of pre-reconstructed composite images. Then the PET image intensities in all voxels were modeled as a kernel matrix multiplied by coefficients and incorporated into the forward model of PET projection data. Then, the coefficients of each feature were estimated by the maximum likelihood method. Using simulated low-count dynamic data of Zubal head phantom, the quantitative performance of the proposed MNLM kernel method was investigated and compared with the maximum-likelihood method, conventional kernel method with and without median filter, and nonlocal means (NLM) kernel method. Simulation results showed that the MNLM kernel method achieved visual and quantitative accuracy improvements (in terms of the ensemble mean squared error, bias versus variance, and contrast versus noise performances). Especially for frame 2 with the lowest count level of a single frame, the MNLM kernel method achieves lower ensemble mean squared error (10.43%) than the NLM kernel method (13.68%), conventional kernel method with and without median filter (11.88% and 23.50%), and MLEM algorithm (24.77%). The study on real low-dose 18F-FDG rat data also showed that the MNLM kernel method outperformed other methods in visual and quantitative accuracy improvements (in terms of regional noise versus intensity mean performance).

Reversal of Regioselectivity in Nucleophilic Difluoroalkylation of α,ß-Enones Employing In Situ-Formed Sterically Encumbered Silylium Catalyst.

An efficient approach for the reversal of regioselectivity in the nucleophilic introduction of difluorinated carbanion into α,ß-enones has been developed via a silylium catalysis. The strong electron-withdrawing properties and bulky substituents of in situ-generated silyl triflic imide catalyst is the key for the 1,4-addition reaction to proceed smoothly. The synthetic utility is highlighted by the further use of this method for the synthesis of 2,4,6-triarylsubstituted 3-fluoropyridines in a one-pot manner.

The Efficacy and Safety of Revefenacin for the Treatment of Chronic Obstructive Pulmonary Disease: A Systematic Review.

Background Revefenacin (REV) is a novel once-daily long-acting muscarinic antagonist (LAMA) in the treatment of moderate to very severe chronic obstructive pulmonary disease (COPD). This systematic review incorporating a dose-response meta-analysis aimed to assess the efficacy and safety of REV. Methods PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, VIP database, and Wanfang database were searched from their inception to April 2020. We included randomized controlled trials (RCTs) which evaluated the efficacy and safety of REV in COPD patients. Two reviewers independently performed study screening, data extraction, and risk of bias assessment. Outcomes consisted of the mean change in trough Forced Expiratory Volume in 1 second (FEV1) from baseline, adverse events (AEs), and serious adverse events (SAEs). A dose-response meta-analysis using the robust error meta-regression method was conducted. We used Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence. Results Nine RCTs (3,121 participants) were included in this systematic review. The meta-analyses indicated that 175 µg/day REV could significantly improve the trough FEV1 (MD=143.67, 95%CI: 129.67 to 157.68; I2=96%; 809 participants; studies=4; low quality) without increasing the risk of AEs (OR=0.98, 95%CI: 0.81 to 1.18; I2=34%; 2,286 participants; studies=7; low quality) or SAEs (OR=0.89, 95%CI: 0.55 to 1.46; I2=0%; 2,318 participants; studies=7; very low quality) compared to placebo. Furthermore, the effect of REV in increasing trough FEV1 was dose-dependent with an effective threshold of 88 µg/day (R2 = 0.7017). Nevertheless, only very low-quality to low-quality evidence showed that REV at a dose of 175 µg/day was inferior to tiotropium regarding the long-term efficacy, and its safety profile was not superior to tiotropium or ipratropium. Conclusion Current evidence shows that REV is a promising option for the treatment of moderate to very severe COPD. Due to most evidence graded as low quality, further studies are required to compare the efficacy, long-term safety and cost-effectiveness between REV and other LAMAs in different populations. Clinical Trial Registration: [PROSPERO], identifier [CRD42020182793].

Experimental study on optimization models for evaluation of fireball characteristics and thermal hazards induced by LNG vapor Cloud explosions based on colorimetric thermometry.

In order to facilitate transport, natural gas is cooled down by a cycle process of compression, condensation, expansion, and evaporation that transforms the gas into a liquid form, as known as Liquefied Natural Gas (LNG). However, once any leak happens in the transportation pipeline, it will result in serious thermal radiant damage due to the explosion fireball induced by LNG Vapor cloud explosions. In this work, an optimization fireball model is proposed by introducing the atmospheric transmission rate τ into the original TNO dynamic model. Based on the colorimetric thermometry technology, a full-scale LNG pipeline explosion experiment has been conducted and a series of testing data for the thermal radiant by VCEs' fireball have been obtained. It is found that theoretical predictions by using optimization model agree well with experimental data. According to the thermal radiant damage criterion, it is concluded that a near 100% fatality radius is expected within the range of 266.3 m and there is a safety area with an ellipse diameter of 1180.1 m. This work attempts to develop optimization fireball models to predict the thermal radiant damage more accurately, and improve the performance of risk assessment on LNG transport and storage industrial process.