A Water-Soluble Highly Oxidizing Cobalt Molecular Catalyst Designed for Bioinspired Water Oxidation.

Herein, we present a stable water-soluble cobalt complex supported by a dianionic 2,2'-([2,2'-bipyridine]-6,6'-diyl)bis(propan-2-ol) ligand scaffold, which is a rare example of a high-oxidation species, as demonstrated by structural, spectroscopic and theoretical data. Electron paramagnetic resonance (EPR) spectroscopy and magnetic susceptibility measurements revealed that the CoIV center of the mononuclear complex in the solid state resides in the high spin state (sextet, S=5/2). The complex can effectively catalyze water oxidation via a single-site water nucleophilic attack pathway with an overpotential of only 360 mV in a phosphate buffer with a pH of 6. The key intermediate toward water oxidation was speculated based on theoretical calculations and was identified by in situ spectroelectrochemical experiments. The results are important regarding the accessibility of high-oxidation state metal species in synthetic models for achieving robust and reactive oxidation catalysis.

Parity and carotid atherosclerosis in elderly Chinese women.

BACKGROUND: The relationship between parity and atherosclerosis has been reported in some ethnic populations. However, results regarding Chinese women are still lacking. This study aimed to investigate the association of parity and carotid atherosclerosis, which has a predictive value of subsequent atherosclerotic events in elderly Chinese women. METHODS: A total of 2, 052 participants from the medical examination center of the Third Xiangya Hospital were enrolled in the study. A standardized, structured questionnaire was administered to collect information on subjects' demographic characteristics, socioeconomic status, and cardiovascular risk factors. High-resolution ultrasound was used to examine carotid plaques and carotid intima-media thickness (IMT). RESULTS: The mean age of participants was 66.1 ± 5.5 years. Women with more birth appeared to have a higher risk of carotid artery plaques. A multivariate-adjusted model yielded an odds ratio of 1.38 (95% CI: 12%-70%, P = 0.003) per birth. A positive association was observed between parity and common carotid IMT (ß ± SE: 0.029 ± 0.006, P < 0.001), and internal carotid IMT (ß ± SE: 0.011 ± 0.005, P = 0.03) in a univariate model; however, these associations became non-significant in multivariate-adjusted models. When common carotid IMT was classified into an IMT ≥ 1 mm group and an IMT < 1 mm group, higher parity was associated with more obvious thickening both in the unadjusted model (OR = 1.61, 95% CI: 1.29-2.00, P < 0.001) and in the fully adjusted model (OR = 1.43, 95% CI: 1.09-1.88, P = 0.01). CONCLUSIONS: There is a positive association between parity and risk of carotid plaques, as well as between parity and risk of obvious thickening for common carotid IMT in elderly Chinese women, indicating multiparous women might experience more atherosclerotic challenges.

The role of radical prostatectomy and definitive external beam radiotherapy in combined treatment for high-risk prostate cancer: a systematic review and meta-analysis.

The first-line treatment options for high-risk prostate cancer (PCa) are definitive external beam radiotherapy (EBRT) with or without androgen deprivation therapy (ADT) and radical prostatectomy (RP) with or without adjuvant therapies. However, few randomized trials have compared the survival outcomes of these two treatments. To systematically evaluate the survival outcomes of high-risk PCa patients treated with EBRT- or RP-based therapy, a comprehensive and up-to-date meta-analysis was performed. A systematic online search was conducted for randomized or observational studies that investigated biochemical relapse-free survival (bRFS), cancer-specific survival (CSS), and/or overall survival (OS), in relation to the use of RP or EBRT in patients with high-risk PCa. The summary hazard ratios (HRs) were estimated under the random effects models. We identified heterogeneity between studies using Q tests and measured it using I2 statistics. We evaluated publication bias using funnel plots and Egger's regression asymmetry tests. Seventeen studies (including one randomized controlled trial [RCT]) of low risk of bias were selected and up to 9504 patients were pooled. When comparing EBRT-based treatment with RP-based treatment, the pooled HRs for bRFS, CSS, and OS were 0.40 (95% confidence interval [CI]: 0.24-0.67), 1.36 (95% CI: 0.94-1.97), and 1.39 (95% CI: 1.18-1.62), respectively. Better OS for RP-based treatment and better bRFS for EBRT-based treatment have been identified, and there was no significant difference in CSS between the two treatments. RP-based treatment is recommended for high-risk PCa patients who value long-term survival, and EBRT-based treatment might be a promising alternative for elderly patients.

The enzyme-like catalytic hydrogen abstraction reaction mechanisms of cyclic hydrocarbons with magnesium-diluted Fe-MOF-74.

Enzymatic heme and non-heme Fe(iv)-O species usually play an important role in hydrogen abstraction of biocatalytic reactions, yet duplicating the reactivity in biomimicry remains a great challenge. Based on Xiao et al.'s experimental work [Nat. Chem., 2014, 6(7), 590], we theoretically found that in the presence of the oxidant N2O, the enzyme-like metal organic framework, i.e., magnesium-diluted Fe-MOF-74 [Fe/(Mg)-MOF-74] can activate the C-H bonds of 1,4-cyclohexadiene (CHD) into benzene with a two-step hydrogen abstraction mechanism based on the density functional theory (DFT) level. It is shown that the first transition state about the cleavage of the N-O bond of N2O to form the Fe(iv)-O species is the rate-determining step with activation enthalpy of 19.4 kcal mol-1 and the complete reaction is exothermic by 62.8 kcal mol-1 on quintet rather than on triplet PES. In addition, we proposed a rebound mechanism of cyclic cyclohexane (CHA) hydroxylation to cyclohexanol which has not been studied experimentally. Note that the activation enthalpies on the first hydrogen abstraction for both cyclic CHD and cyclohexane are just 8.1 and 3.5 kcal mol-1, respectively, which are less than that of 13.9 kcal mol-1 for chained ethane. Most importantly, for the hydrogen abstraction of methane catalyzed by M/(Mg)-MOF-74 (M = Cu, Ni, Fe, and Co), we found that the activation enthalpies versus the C-H bond length of methane of TSs, NPA charge of the reacting oxyl atom have linear relationships with different slopes, i.e., shorter C-H bond and less absolute value of NPA charge of oxyl atom are associated with lower activation enthalpy; while for the activation of methane, ethane, propane and CHD catalyzed by Fe/(Mg)-MOF-74, there also exists positive correlations between activation enthalpies, bond dissociation energies (BDEs) and C-H bond lengths in TSs, respectively. We hope the present theoretical study may provide the guideline to predict the performance of MOFs in C-H bond activation reactions.