Efficient direct conversion of methane into methanol on CuZn hetero-diatomic catalysts with certain coordination spheres: a DFT study.

The oxidation of methane to a high-value-added chemical, methanol, is a major challenge in catalysis, requiring high energy input to overcome the CH3-H bond activation energy barrier. Based on density functional theory (DFT) calculations, methane oxidation to methanol is catalyzed by hetero-diatomic catalysts (CuZn-NG) with different coordination spheres (CSs). Valence band maximum (VBM), atomic charge and d-band center are selected as analysis methods for the pathway selection and activity of catalysis. The VBM plays a vital role in the catalytic pathway selection, CuZn-NG catalyzes the direct conversion of methane into methanol without side reactions. Alarmingly, the most important reaction step, CH3-H bond activation, is a spontaneously exothermic reaction (releasing 0.06 eV) with CuZn-NPAG as the catalyst, in contrast to most other endothermic reactions in the same activation. By analyzing the atomic charge of the Cu center and O atom, the special electronic phenomenon for this important step is summarized as the "bow-release effect". The CS affects the electronic properties of the active center and further affects the methane oxidation activity. This work provides a useful guide to understand the catalytic selectivity and activity of hetero-diatomic catalysts.

Multiple links between 5-methylcytosine content of mRNA and translation.

BACKGROUND: 5-Methylcytosine (m5C) is a prevalent base modification in tRNA and rRNA but it also occurs more broadly in the transcriptome, including in mRNA, where it serves incompletely understood molecular functions. In pursuit of potential links of m5C with mRNA translation, we performed polysome profiling of human HeLa cell lysates and subjected RNA from resultant fractions to efficient bisulfite conversion followed by RNA sequencing (bsRNA-seq). Bioinformatic filters for rigorous site calling were devised to reduce technical noise. RESULTS: We obtained ~ 1000 candidate m5C sites in the wider transcriptome, most of which were found in mRNA. Multiple novel sites were validated by amplicon-specific bsRNA-seq in independent samples of either human HeLa, LNCaP and PrEC cells. Furthermore, RNAi-mediated depletion of either the NSUN2 or TRDMT1 m5C:RNA methyltransferases showed a clear dependence on NSUN2 for the majority of tested sites in both mRNAs and noncoding RNAs. Candidate m5C sites in mRNAs are enriched in 5'UTRs and near start codons and are embedded in a local context reminiscent of the NSUN2-dependent m5C sites found in the variable loop of tRNA. Analysing mRNA sites across the polysome profile revealed that modification levels, at bulk and for many individual sites, were inversely correlated with ribosome association. CONCLUSIONS: Our findings emphasise the major role of NSUN2 in placing the m5C mark transcriptome-wide. We further present evidence that substantiates a functional interdependence of cytosine methylation level with mRNA translation. Additionally, we identify several compelling candidate sites for future mechanistic analysis.

Switch effect on controlled water splitting by biaxial strain regulating the promising two-dimensional Janus X2PAs (X = Si, Ge and Sn) photocatalyst.

Two-dimensional photocatalytic materials with unique properties have been well-reported in recent decades. However, strategies for controlling the photocatalytic process are still ongoing. Herein, Janus X2PAs (X = Si, Ge and Sn) monolayers have been explored by first-principles calculations to meet this challenge. All strain-free X2PAs monolayers exhibit excellent photocatalytic properties with high carrier mobility (2.39 × 102-1.34 × 104 cm2 V-1 s-1), suitable band edge positions straddling the standard redox potential of water and large visible light absorption coefficients (up to 105 cm-1). Most importantly, a reaction switch effect is proposed for the first time towards controlling the microscopic photocatalytic process of water splitting on X2PAs monolayers through macroscopic mechanical strain. This effect renders the Janus X2PAs photocatalytic switches among the states of only oxygen evolution reaction, only hydrogen evolution reaction and the full redox reaction for controlled water splitting. This work not only provides a new avenue for designing highly tunable photocatalysts but also offers new physical insights into controlling the photocatalytic water-splitting reaction.

Electronic properties of double-atom catalysts for electrocatalytic oxygen evolution reaction in alkaline solution: a DFT study.

In alkaline solution, the electrocatalytic oxygen evolution reaction (OER) of dual transition metal atom (2TM) nitrogen-decorated graphene as a double-atom catalyst (DAC) has received special attention. Here, using density functional theory (DFT) calculations, the OER electrocatalysis of 2TM-pyridine/amino-nitrogen-decorated graphene (2TM-NPAG and 2TM-NPG. 2TM represents FeCo, FeNi, Conti) is studied. The electrocatalytic OER mechanism is that 2TM-NPG acts as the pre-catalyst, while the real catalysts are 2TM-NPAG and 2TM-NPG-O. In particular, CoNi-NPAG and CoNi-NPG-O exhibit higher OER activity compared to state-of-the-art RuO2 at pH = 14. It is confirmed that the potential-determining step is also the rate-determining step. Amino-nitrogen is the main accepter of electrons from CoNi atoms and pyridine-nitrogen is the main acceptor of electrons from nearby C atoms. The role of different N coordination continues to influence the entire electrocatalytic OER process of CoNi-NG. Simultaneously, the overpotential of CoNi-NG is in a volcano-shaped relationship with the electronic properties (oxidation state or d-band center) of the catalytic site of Co. Moreover, CoNi-NPAG and CoNi-NPG-O are the closest to the center of the OER overpotential (a function of the d-band center and oxidation state) contour plot, implying that they exhibit the best catalytic activity among all the CoNi-NG materials. The optimal electronic properties of CoNi-NPAG and CoNi-NPG-O contribute towards their excellent OER performance, and provide a new breakthrough in developing high-performance DACs.

Increasing body mass index identifies Chinese patients with type 2 diabetes mellitus at risk of poor outcomes.

AIMS: Association between body mass index (BMI) and glycemic control, comorbidities/complications, and health-related quality of life (HRQoL) was assessed in Chinese patients with type 2 diabetes mellitus (T2DM) enrolled in the Diabetes Disease Specific Programme. METHODS: Surveys of 200 physicians and 2052 patients with T2DM captured demographic, clinical, and HRQoL information. Adjusted and unadjusted analyses were conducted across 3 BMI groups; normal (18.5-<24.0, n=998), overweight (24.0-<28.0, n=822), and obese (≥28.0, n=212). RESULTS: There were no between group differences in the achievement of glycated hemoglobin (HbA1c) <7.0% (48mmol/mol); however, compared with the normal BMI group, more obese patients had an HbA1c >9.0% (75mmol/mol; 4.3% vs 10.2%, P=0.002). More obese patients compared with normal BMI patients had hypertension (48.6% vs 35.3%, P<0.001), dyslipidemia (35.4% vs 18.8%, P<0.001), or both hypertension and dyslipidemia (24.1% vs 13.9%, P<0.001). Patients in the obese group reported worse HRQoL and greater effects of diabetes on their daily living. CONCLUSIONS: Obesity in Chinese patients with T2DM results in poor glycemic control, more comorbidities, and worse HRQoL. Management of these patients should include efforts to reduce weight. Selection of weight-neutral or weight-reducing anti-diabetic medications maybe useful in these patients.