Determining the TiO₂‑Photocatalytic Aryl-Ring-Opening Mechanism in Aqueous Solution Using Oxygen-18 Labeled O₂ and H₂O

The molecules O₂ and H₂O dominate the cleavage of aromatic sp² C–C bonds, a crucial step in the degradation of aromatic pollutants in aqueous TiO₂ photocatalysis, but their precise roles in this process have remained elusive. This can be attributed to the complex oxidative species involved and to a lack of available models for reactions with a high yield of direct products. Here, we used oxygen-18 isotope labeled O₂ and H₂O to observe the aromatic ring-opening reaction of the model compound 3,5-di-<i>tert</i>-butylcatechol (DTBC), which was mediated by TiO₂ photocatalysis in an aqueous acetonitrile solution. By analyzing the primary intermediate products (∼75% yield), especially the seven-membered ring anhydrides that were formed, we obtained direct evidence for the oxygen atom of dioxygen insertion into a C–C bond of the aromatic ring. This indicates that molecular oxygen is the ultimate ring-opening agent in TiO₂ photocatalysis and that it undergoes single O atom incorporation rather than the previously proposed molecular oxygen 1,2-addition processes. The ratio of intradiol to extradiol products depends on the particle size of TiO₂ catalysts used, which suggests that the O₂ activation is correlated with the available coordination sites on the TiO₂ surface in the photocatalytic cleavage of the aromatic ring

Pivotal Role and Regulation of Proton Transfer in Water Oxidation on Hematite Photoanodes

Hematite is a promising material for solar water splitting; however, high efficiency remains elusive because of the kinetic limitations of interfacial charge transfer. Here, we demonstrate the pivotal role of proton transfer in water oxidation on hematite photoanodes using photoelectrochemical (PEC) characterization, the H/D kinetic isotope effect (KIE), and electrochemical impedance spectroscopy (EIS). We observed a concerted proton–electron transfer (CPET) characteristic for the rate-determining interfacial hole transfer, where electron transfer (ET) from molecular water to a surface-trapped hole was accompanied by proton transfer (PT) to a solvent water molecule, demonstrating a substantial KIE (∼3.5). The temperature dependency of KIE revealed a highly flexible proton transfer channel along the hydrogen bond at the hematite/electrolyte interface. A mechanistic transition in the rate-determining step from CPET to ET occurred after OH^– became the dominant hole acceptor. We further modified the proton–electron transfer sequence with appropriate proton acceptors (buffer bases) and achieved a greater than 4-fold increase in the PEC water oxidation efficiency on a hematite photoanode

Early-Onset Hypertension and Sex-Specific Residual Risk for Cardiovascular Disease in Type 2 Diabetes Mellitus

Objective. To investigate whether the sex disparities in type 2 diabetes associated cardiovascular disease (CVD) risks may be related to early-onset hypertension that could benefit from intensive blood pressure (BP) control.Research Design and Methods. We analyzed intensive versus standard BP control in relation to incident CVD events in women and men with type 2 diabetes, based on their age of hypertension diagnosis.Results. Among 3792 adults with type 2 diabetes (49% women), multivariable-adjusted CVD risk was increased per decade earlier age at hypertension diagnosis (HR 1.11 [1.03-1.21], P=0.006). Excess risk associated with early-diagnosed hypertension was attenuated in the presence of intensive versus standard antihypertensive therapy in women (P=0.036) but not men (P=0.76).Conclusions. Women with type 2 diabetes and early-onset hypertension may represent a higher-risk subpopulation that not only contributes to the female excess in diabetes-related CVD risk but that may benefit from intensive BP control.</p

Hydrogen-Bond Bridged Water Oxidation on {001} Surfaces of Anatase TiO₂

To gain an atomic-level understanding of the relationship among the surface structure, the interfacial interaction, and the water oxidation activity on TiO₂, we studied the adsorption of water and its photocatalytic oxidation on anatase TiO₂ with {101} and {001} exposed surfaces by in situ infrared spectroscopy, kinetic isotope effect studies, and density functional theory (DFT)-based molecular dynamics calculations. Our experimental results demonstrate that the oxidation reaction occurs exclusively on hydrogen-bonded water molecules (via surface hydroxyls) over {001} surface, whereas water molecules coordinated on the {101} surface, which are conventionally assigned to the reactive target for hole transfer, remain unchanged during the irradiation. The theoretical calculations reveal that the selective oxidation of water adsorbed on the {001} surfaces is primarily attributed to the formation of hydrogen bonds, which provides a channel to the rapid hole transfer and facilitates the O–H bond cleavage during water oxidation

Gradient FeO_<i>x</i>(PO₄)_<i>y</i> Layer on Hematite Photoanodes: Novel Structure for Efficient Light-Driven Water Oxidation

Hematite has been receiving increasing attention for its application in photoelectrochemical (PEC) water oxidation but usually exhibits poor efficiency. We fabricated a stable gradient-structured FeO_<i>x</i>(PO₄)_<i>y</i> layer on hematite by diffusively incorporating phosphate onto the surface layer of hematite films at a low temperature. X-ray photoelectron spectroscopy depth profile and Fe K-edge grazing-incidence X-ray absorption near-edge structure and extended X-ray absorption fine structure analysis demonstrated the formation of a ∼50 nm overlayer with a gradient phosphorus distribution and structural evolution from the outer surface to the depth. The as-prepared photoanodes showed highly improved PEC water oxidation performance. Up to 8.5-fold enhancement in the photocurrent density at 1.23 V versus reversible hydrogen electrode was achieved relative to the pristine anode. This strategy is applicable for hematite photoanodes prepared by different methods and with different morphologies and structures. The improvement in the water oxidation activity is mainly attributed to the enhanced separation of photogenerated electron–hole pairs, which is derived from the increased hole diffusion length in the gradient-structured overlayer. This work develops a simple and universal method to boost the PEC water oxidation efficiency with versatile hematite photoanodes

The Formation of Ti–H Species at Interface Is Lethal to the Efficiency of TiO₂‑Based Dye-Sensitized Devices

TiO₂-based dye-sensitization cycle is one of the basic strategies for the development of solar energy applications. Although the power conversion efficiency (PCE) of dye-sensitized devices has been improved through constant attempts, the intrinsically fatal factor that leads to the complete failure of the PCE of TiO₂-mediated dye-sensitized devices has not yet been determined. Here, by using isotopically labeled MAS–¹H NMR, ATR-FTIR spectroscopy (separate H/D and ⁴⁸Ti/⁴⁹Ti experiments), and ESR, we revealed that the accumulative formation of Ti–H species on the TiO₂ surface is the intrinsic cause of the PCE failure of TiO₂-based dye-sensitization devices. Such a Ti–H species is generated from the reduction of hydrogen ions (mostly released from dye carboxyl groups or organic electrolyte) accompanied by electron injection on the surface of TiO₂, which deteriorates the PCE mainly by reducing the electrical conductivity of the TiO₂ (by a maximum of ∼80%) and the hydrophilic nature of the TiO₂ surface (contact angle increased)

Datasheet1_Association of age at menarche with valvular heart disease: An analysis based on electronic health record (CREAT2109).docx

BackgroundThe association between age at menarche and coronary heart disease has been reported, but the association between age at menarche and valvular heart disease (VHD) has not been described. We aimed to examine the association between age at menarche and VHD.MethodsBy collecting data from four medical centers of the Affiliated Hospital of Qingdao University (QUAH) from January 1, 2016, to December 31, 2020, we sampled 105,707 inpatients. The main outcome of this study was newly diagnosed VHD, which was diagnosed based on ICD-10 coding, and the exposure factor was age at menarche, which was accessed through the electronic health records. We used logistic regression model to investigate the association between age at menarche and VHD.ResultsIn this sample (mean age 55.31 ± 13.63 years), the mean age at menarche was 15. Compared with women with age at menarche 14–15 years, the odds ratio of VHD in women with age at menarche ≤13, 16–17, and ≥18 years was 0.68 (95% CI 0.57–0.81), 1.22 (95% CI 1.08–1.38), and 1.31 (95% CI 1.13–1.52), respectively (P for all ConclusionsIn this large inpatient sample, later menarche was associated with higher risk of VHD.</p