Structural and functional characterizations of infectivity and immune evasion of SARS-CoV-2 Omicron.

The SARS-CoV-2 Omicron variant with increased fitness is spreading rapidly worldwide. Analysis of cryo-EM structures of the spike (S) from Omicron reveals amino acid substitutions forging interactions that stably maintain an active conformation for receptor recognition. The relatively more compact domain organization confers improved stability and enhances attachment but compromises the efficiency of the viral fusion step. Alterations in local conformation, charge, and hydrophobic microenvironments underpin the modulation of the epitopes such that they are not recognized by most NTD- and RBD-antibodies, facilitating viral immune escape. Structure of the Omicron S bound with human ACE2, together with the analysis of sequence conservation in ACE2 binding region of 25 sarbecovirus members, as well as heatmaps of the immunogenic sites and their corresponding mutational frequencies, sheds light on conserved and structurally restrained regions that can be used for the development of broad-spectrum vaccines and therapeutics.

Population flow drives spatio-temporal distribution of COVID-19 in China.

Sudden, large-scale and diffuse human migration can amplify localized outbreaks of disease into widespread epidemics1-4. Rapid and accurate tracking of aggregate population flows may therefore be epidemiologically informative. Here we use 11,478,484 counts of mobile phone data from individuals leaving or transiting through the prefecture of Wuhan between 1 January and 24 January 2020 as they moved to 296 prefectures throughout mainland China. First, we document the efficacy of quarantine in ceasing movement. Second, we show that the distribution of population outflow from Wuhan accurately predicts the relative frequency and geographical distribution of infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) until 19 February 2020, across mainland China. Third, we develop a spatio-temporal 'risk source' model that leverages population flow data (which operationalize the risk that emanates from epidemic epicentres) not only to forecast the distribution of confirmed cases, but also to identify regions that have a high risk of transmission at an early stage. Fourth, we use this risk source model to statistically derive the geographical spread of COVID-19 and the growth pattern based on the population outflow from Wuhan; the model yields a benchmark trend and an index for assessing the risk of community transmission of COVID-19 over time for different locations. This approach can be used by policy-makers in any nation with available data to make rapid and accurate risk assessments and to plan the allocation of limited resources ahead of ongoing outbreaks.

Ultratrace Aromatic Anhydride Dopant as Intermediate Island to Promote Charge Transfer of Graphitic Carbon Nitride for Enhancing the Photocatalytic Degradation of Rhodamine B.

In this work, 0.75 wt ‰ 2,3-pyridinedicarboxylic anhydride (PDA) as a novel dopant was utilized to obtain modified graphitic carbon nitride with ultratrace doping (3MCN-PDA3) by facile thermal polymerization. Characterization of the microstructure, surface state, and porosity properties of the samples indicated that 3MCN-PDA3 has a thinner sheet-like, larger-scale, and tighter lamellar stacking structure than that of pristine graphitic carbon nitride (3MCN). Based on photo/electrochemical analysis, the PDA dopant formed an extended coplanar conjugated system by anhydride-amine thermal condensation with heptazine rings, and the channels of amide covalent bonds and superconjugation of the solitary pair of electrons of the nitrogen atoms of PDA synergistically promoted the charge transport performance of 3MCN-PDA3. Under visible light, the photodegradation efficiency of Rhodamine B (RhB) over 3MCN-PDA3 reached 92.4% in 60 min and realized almost entire removal in 200 min (99.2%), 1.43 times that of 3MCN. Furthermore, the experimental results and generalized density theory calculations confirmed that PDA acts as an intermediate molecular island and constructs an efficient carrier transfer pathway between different heptazine units. The results indicate that PDA is a promising candidate to enhance the charge transfer performance through ultratrace doping in the large-scale preparation and application of the graphitic carbon nitride photocatalyst.

Synthesis of Indole-Substituted Trifluoromethyl Sulfonium Ylides by Cp*Rh(III)-Catalyzed Diazo-carbenoid Addition to Trifluoromethylthioether.

The indole-substituted trifluoromethyl sulfonium ylide has been developed via Cp*Rh(III)-catalyzed diazo-carbenoid addition to trifluoromethylthioether and is the first example of an Rh(III)-catalyzed diazo-carbenoid addition reaction with trifluoromethylthioether. Several kinds of indole-substituted trifluoromethyl sulfonium ylide were constructed under mild reaction conditions. The reported method exhibited high functional group compatibility and broad substrate scope. In addition, the protocol was found to be complementary to the method disclosed by a Rh(II) catalyst.

"We don't have a template to follow": Sexual identity development and its facilitative factors among sexual minority men in the context of China.

Extant research on sexual identity development among sexual minority individuals has been predominantly conducted in Western contexts and focused on factors that hinder identity development processes. Using thematic analysis, this qualitative study sought to explore the experiences of sexual identity development among Chinese sexual minority men as well as the facilitative factors in China that positively influence this developmental process. The sample comprised 24 participants who self-identified as Chinese sexual minority men. The analysis yielded five overarching themes: awareness of one's attraction and corresponding reactions, identity exploration, moving toward identity acceptance and commitment, acceptance and support from others, and environmental support. The first three themes described the processes of sexual identity development among Chinese sexual minority men, whereas the latter two themes centered on the related facilitative factors in the context of China. The results highlight the importance of understanding the identity development process within Chinese minority men's unique sociocultural contexts. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Genome-Wide mRNA and Long Non-Coding RNA Analysis of Porcine Trophoblast Cells Infected with Porcine Reproductive and Respiratory Syndrome Virus Associated with Reproductive Failure.

Porcine reproductive and respiratory syndrome (PRRS) is a vertically transmitted reproductive disorder that is typically characterized by miscarriage, premature birth, and stillbirth in pregnant sows after infection. Such characteristics indicate that PRRSV can infect and penetrate the porcine placental barrier to infect fetus piglets. The porcine trophoblast is an important component of the placental barrier, and secretes various hormones, including estrogen and progesterone, to maintain normal pregnancy and embryonic development during pregnancy. It is conceivable that the pathogenic effects of PRRSV infection on porcine trophoblast cells may lead to reproductive failure; however, the underlying detailed mechanism of the interaction between porcine trophoblast (PTR2) cells and PRRSV is unknown. Therefore, we conducted genome-wide mRNA and long non-coding RNA (lncRNA) analysis profiling in PRRSV-infected PTR2. The results showed that 672 mRNAs and 476 lncRNAs were significantly different from the control group after viral infection. Target genes of the co-expression and co-location of differential mRNAs and lncRNAs were enriched by GO (gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis, revealing that most of the pathways were involved in cell nutrient metabolism, cell proliferation, and differentiation. Specifically, the estrogen signaling pathway, the PI3K (PhosphoInositide-3 Kinase)-Akt (serine/threonine kinase) signaling pathway, and the insulin secretion related to embryonic development were selected for analysis. Further research found that PRRSV inhibits the expression of G-protein-coupled estrogen receptor 1 (GPER1), thereby reducing estrogen-induced phosphorylation of AKT and the mammalian target of rapamycin (mTOR). The reduction in the phosphorylation of AKT and mTOR blocks the activation of the GPER1- PI3K-AKT-mTOR signaling pathway, consequently restraining insulin secretion, impacting PTR2 cell proliferation, differentiation, and nutrient metabolism. We also found that PRRSV triggered trophoblast cell apoptosis, interrupting the integrity of the placental villus barrier. Furthermore, the interaction network diagram of lncRNA, regulating GPER1 and apoptosis-related genes, was constructed, providing a reference for enriching the functions of these lncRNA in the future. In summary, this article elucidated the differential expression of mRNA and lncRNA in trophoblast cells infected with PRRSV. This infection could inhibit the PI3K-AKT-mTOR pathway and trigger apoptosis, providing insight into the mechanism of the vertical transmission of PRRSV and the manifestation of reproductive failure.

Chinese Guideline on the Management of Polypoidal Choroidal Vasculopathy (2022).

Background In mainland China, patients with neovascular age-related macular degeneration (nAMD) have approximately an 40% prevalence of polypoidal choroidal vasculopathy (PCV). This disease leads to recurrent retinal pigment epithelium detachment (PED), extensive subretinal or vitreous hemorrhages, and severe vision loss. China has introduced various treatment modalities in the past years and gained comprehensive experience in treating PCV.Methods A total of 14 retinal specialists nationwide with expertise in PCV were empaneled to prioritize six questions and address their corresponding outcomes, regarding opinions on inactive PCV, choices of anti-vascular endothelial growth factor (anti-VEGF) monotherapy, photodynamic therapy (PDT) monotherapy or combined therapy, patients with persistent subretinal fluid (SRF) or intraretinal fluid (IRF) after loading dose anti-VEGF, and patients with massive subretinal hemorrhage. An evidence synthesis team conducted systematic reviews, which informed the recommendations that address these questions. This guideline used the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach to assess the certainty of evidence and grade the strengths of recommendations. Results The panel proposed the following six conditional recommendations regarding treatment choices. (1) For patients with inactive PCV, we suggest observation over treatment. (2) For treatment-na?ve PCV patients, we suggest either anti-VEGF monotherapy or combined anti-VEGF and PDT rather than PDT monotherapy. (3) For patients with PCV who plan to initiate combined anti-VEGF and PDT treatment, we suggest later/rescue PDT over initiate PDT. (4) For PCV patients who plan to initiate anti-VEGF monotherapy, we suggest the treat and extend (T&E) regimen rather than the pro re nata (PRN) regimen following three monthly loading doses. (5) For patients with persistent SRF or IRF on optical coherence tomography (OCT) after three monthly anti-VEGF treatments, we suggest proceeding with anti-VEGF treatment rather than observation. (6) For PCV patients with massive subretinal hemorrhage (equal to or more than four optic disc areas) involving the central macula, we suggest surgery (vitrectomy in combination with tissue-plasminogen activator (tPA) intraocular injection and gas tamponade) rather than anti-VEGF monotherapy. Conclusions Six evidence-based recommendations support optimal care for PCV patients' management.

Enantioselective Synthesis of cis-Decalins by Merging the Birch Reduction and Inverse-Electron-Demand Diels-Alder Reaction.

Herein, we show that the combination of the Birch reduction of readily available anisole derivatives and the catalytic asymmetric inverse-electron-demand Diels-Alder reaction of 2-pyrones can serve as a powerful platform for the diverse synthesis of synthetically important cis-decalin scaffolds. Enabled by a well-modified chiral bis(oxazoline) ligand/CuII complex, a wide range of polysubstituted cis-decalin scaffolds with up to six contiguous stereocenters were generated efficiently. The synthetic potential of this method is demonstrated by the concise synthesis of the sesquiterpene (+)-occidentalol and a key intermediate for seven triterpenes. Mechanistic studies suggest the 1,3-cyclohexadienes formed in situ are the key intermediates, and efficient kinetic resolution occurs when C2- and/or C3-substituted 1,4-cyclohexadienes are utilized as substrates. DFT calculations elucidated that the Diels-Alder reaction proceeds in a stepwise fashion and revealed the origins of the stereoselectivities.

Enantioselective Synthesis of Inherently Chiral Calix[4]arenes via Palladium-Catalyzed Asymmetric Intramolecular C-H Arylations.

We report herein an efficient approach for the enantioselective synthesis of inherently chiral calix[4]arenes via palladium-catalyzed asymmetric intramolecular C-H arylations. Using a chiral bifunctional phosphine-carboxylate ligand, the inherent chirality on macrocyclic scaffolds was induced successfully, from which a wide range of calix[4]arenes with fluorenone motifs were obtained with good yields and excellent enantioselectivities (up to >99% ee). The synthetic utility of this method was demonstrated by diverse transformations of the products, thus substantially expanding the chemical space of chiral calix[4]arenes. Further investigations of photophysical and chiroptical properties revealed that calix[4]arenes bearing two fluorenone moieties displayed remarkable glum values (up to 0.019), highlighting the great potential of inherent chirality in the development of organic optoelectronic materials.

A Versatile Platform for Sensitive and Label-Free Identification of Biomarkers through an Exo-III-Assisted Cascade Signal Amplification Strategy.

The development of a versatile and sensitive analytical biomarker detection platform is important for both early diagnosis and treatment of diseases. In the present study, we propose a novel fluorescence-based, ultrasensitive, and label-free biomarker detection platform. This platform relies on a flexible probe design compatible for multiple biomarker identification and Exo-III enzyme-triggered cascade signal amplification. We have validated that this label-free platform exhibits high sensitivity and specificity. Indeed, this platform exhibited brilliant analytical performance in qualifying a carcinoembryonic antigen and small extracellular vesicles (sEVs). It also shows excellent capability in multiplexing mapping of surface proteins of various cancer-derived sEVs. Therefore, we believe that the proposed sensing platform has great potential for clinical diagnosis and anticancer drug development.

Dihydroartemisinin induces cell apoptosis through repression of UHRF1 in prostate cancer cells.

Prostate cancer (PCa) seriously jeopardizes men's health worldwide. Dihydroartemisinin, which is an effective antimalarial agent, has shown potential anticancer effects in various human cancer cell lines, including PCa cells. However, the mechanisms underlying the anticancer activity of dihydroartemisinin are not fully understood. Ubiquitin-like with plant homeodomain and ring finger domain 1 (UHRF1) is highly expressed in a variety of tumors and is negatively correlated with the prognosis of various tumors. We reported previously that UHRF1 is downregulated during apoptosis induced by dihydroartemisinin in PC-3 PCa cells. In this study, we transfected PC-3 cells with lentiviruses containing UHRF1 or shRNA-UHRF1. Then, the cells were treated with dihydroartemisinin at different concentrations. Our data showed that overexpression of UHRF1 promoted cell proliferation and migration in PC-3 cells, inhibited cell apoptosis, increased cell proportion in G2 phase, increased DNA methyltransferase 1 and decreased p16INK4A expression at mRNA and protein levels. Downregulation of UHRF1 produces the opposite results. Moreover, the phenomena caused by overexpression of UHRF1 were inhibited after dihydroartemisinin treatment. Compared with control cells, cells overexpressing UHRF1 can resist the proapoptotic and antiproliferative effects of dihydroartemisinin to a certain extent. The effects of UHRF1 knockdown were further aggravated by dihydroartemisinin treatment, but no statistically significant effect was observed with increasing drug concentration. Our results suggested that dihydroartemisinin decreases proliferation and migration but enhances apoptosis of PCa cells, likely by downregulating UHRF1 and upregulating p16INK4A.

Thioether-directed Rh(III)-catalyzed peri-selective acyloxylation of arenes.

A thioether directed acyloxylation of arenes has been realized via Cp*Rh(III)-catalyzed C-H activation and subsequent coupling with carboxylic acids. This new method showed high functional group compatibility and broad substrate scope. Primary mechanistic studies have been conducted and a tentative reaction mechanism was proposed. It represents the first example of a thioether-directed Cp*Rh(III)-catalyzed C(sp2)-H acyloxylation reaction.

Reciprocal regulation of NRF2 by autophagy and ubiquitin-proteasome modulates vascular endothelial injury induced by copper oxide nanoparticles.

NRF2 is the key antioxidant molecule to maintain redox homeostasis, however the intrinsic mechanisms of NRF2 activation in the context of nanoparticles (NPs) exposure remain unclear. In this study, we revealed that copper oxide NPs (CuONPs) exposure activated NRF2 pathway in vascular endothelial cells. NRF2 knockout remarkably aggravated oxidative stress, which were remarkably mitigated by ROS scavenger. We also demonstrated that KEAP1 (the negative regulator of NRF2) was not primarily involved in NRF2 activation in that KEAP1 knockdown did not significantly affect CuONPs-induced NRF2 activation. Notably, we demonstrated that autophagy promoted NRF2 activation as evidenced by that ATG5 knockout or autophagy inhibitors significantly blocked NRF2 pathway. Mechanically, CuONPs disturbed ubiquitin-proteasome pathway and consequently inhibited the proteasome-dependent degradation of NRF2. However, autophagy deficiency reciprocally promoted proteasome activity, leading to the acceleration of degradation of NRF2 via ubiquitin-proteasome pathway. In addition, the notion that the reciprocal regulation of NRF2 by autophagy and ubiquitin-proteasome was further proven in a CuONPs pulmonary exposure mice model. Together, this study uncovers a novel regulatory mechanism of NRF2 activation by protein degradation machineries in response to CuONPs exposure, which opens a novel intriguing scenario to uncover therapeutic strategies against NPs-induced vascular injury and disease.

PINK1/TAX1BP1-directed mitophagy attenuates vascular endothelial injury induced by copper oxide nanoparticles.

Copper oxide nanoparticles (CuONPs) are widely used metal oxide NPs owing to their excellent physical-chemical properties. Circulation translocation of CuONPs after inhalation leads to vascular endothelial injury. Mitochondria, an important regulatory hub for maintaining cell functions, are signaling organelles in responses to NPs-induced injury. However, how mitochondrial dynamics (fission and fusion) and mitophagy (an autophagy process to degrade damaged mitochondria) are elaborately orchestrated to maintain mitochondrial homeostasis in CuONPs-induced vascular endothelial injury is still unclear. In this study, we demonstrated that CuONPs exposure disturbed mitochondrial dynamics through oxidative stress-dependent manner in vascular endothelial cells, as evidenced by the increase of mitochondrial fission and the accumulation of fragmented mitochondria. Inhibition of mitochondrial fission with Mdivi-1 aggravated CuONPs-induced mtROS production and cell death. Furthermore, we found that mitochondrial fission led to the activation of PINK1-mediated mitophagy, and pharmacological inhibition with wortmannin, chloroquine or genetical inhibition with siRNA-mediated knockdown of PINK1 profoundly repressed mitophagy, suggesting that the protective role of mitochondrial fission and PINK1-mediated mitophagy in CuONPs-induced toxicity. Intriguingly, we identified that TAX1BP1 was the primary receptor to link the ubiquitinated mitochondria with autophagosomes, since TAX1BP1 knockdown elevated mtROS production, decreased mitochondrial clearance and aggravated CuONPs-induced cells death. More importantly, we verified that urolithin A, a mitophagy activator, promoted mtROS clearance and the removal of damaged mitochondria induced by CuONPs exposure both in vitro and in vivo. Overall, our findings indicated that modulating mitophagy may be a therapeutic strategy for pathological vascular endothelial injury caused by NPs exposure.

The effects of gestational diabetes mellitus with maternal age between 35 and 40 years on the metabolite profiles of plasma and urine.

BACKGROUND: Gestational diabetes mellitus (GDM) is defined as impaired glucose tolerance in pregnancy and without a history of diabetes mellitus. While there are limited metabolomic studies involving advanced maternal age in China, we aim to investigate the metabolomic profiling of plasma and urine in pregnancies complicated with GDM aged at 35-40 years at early and late gestation. METHODS: Twenty normal and 20 GDM pregnant participants (≥ 35 years old) were enlisted from the Complex Lipids in Mothers and Babies (CLIMB) study. Maternal plasma and urine collected at the first and third trimester were detected using gas chromatography-mass spectrometry (GC-MS). RESULTS: One hundred sixty-five metabolites and 192 metabolites were found in plasma and urine respectively. Urine metabolomic profiles were incapable to distinguish GDM from controls, in comparison, there were 14 and 39 significantly different plasma metabolites between the two groups in first and third trimester respectively. Especially, by integrating seven metabolites including cysteine, malonic acid, alanine, 11,14-eicosadienoic acid, stearic acid, arachidic acid, and 2-methyloctadecanoic acid using multivariant receiver operating characteristic models, we were capable of discriminating GDM from normal pregnancies with an area under curve of 0.928 at first trimester. CONCLUSION: This study explores metabolomic profiles between GDM and normal pregnancies at the age of 35-40 years longitudinally. Several compounds have the potential to be biomarkers to predict GDM with advanced maternal age. Moreover, the discordant metabolome profiles between the two groups could be useful to understand the etiology of GDM with advanced maternal age.

Increased admission serum total bile acids can be associated with decreased 3-month mortality in patients with acute ischemic stroke.

BACKGROUND: Bile acids (BAs) not only play an important role in lipid metabolism and atherosclerosis but also have antiapoptotic and neuroprotective effects. However, few studies have focused on the relationship of the total bile acid (TBA) levels with the severity and prognosis of acute ischemic stroke (AIS). OBJECTIVES: The aim of this study was to investigate the potential associations of the fasting serum TBA levels on admission with the stroke severity, in-hospital complication incidence and 3 -month all-cause mortality in patients with AIS. METHODS: A total of 777 consecutive AIS patients were enrolled in this study and were divided into four groups according to the quartiles of the serum TBA levels on admission. Univariate and multivariate logistic regression analyses were used to explore the relationship between the fasting TBA levels and the stroke severity, in-hospital complications, and 3-month mortality in AIS patients. RESULTS: Patients in group Q3 had the lowest risk of severe AIS (NIHSS > 10) regardless of the adjustments for confounders (P < 0.05). During hospitalization, 115 patients (14.8%) had stroke progression (NIHSS score increased by ≥ 2), and 222 patients (28.6%) developed at least one complication, with no significant difference among the four groups (P > 0.05). There was no significant difference in the incidence of pneumonia, urinary tract infection (UTI), hemorrhagic transformation (HT), gastrointestinal bleeding (GIB), seizures or renal insufficiency (RI) among the four groups (P > 0.05). A total of 114 patients (14.7%) died from various causes (including in-hospital deaths) at the 3-month follow-up, including 42 (21.3%), 26 (13.3%), 19 (9.9%) and 27 (13.9%) patients in groups Q1, Q2, Q3 and Q4 respectively, with significant differences (P = 0.013). After adjusting for confounding factors, the risk of death decreased (P -trend < 0.05) in groups Q2, Q3, and Q4 when compared with group Q1, and the OR values were 0.36 (0.16-0.80), 0.30 (0.13-0.70), and 0.29 (0.13-0.65), respectively. CONCLUSIONS: TBA levels were inversely associated with the 3-month mortality of AIS patients but were not significantly associated with the severity of stroke or the incidence of complications.

Landscape of clinical trial activity focusing on Indigenous health in Australia: an overview using clinical trial registry data from 2008-2018.

BACKGROUND: Aboriginal and Torres Strait Islander peoples (hereafter respectfully referred to as Indigenous Australians) represent about 3% of the total Australian population. Major health disparities exist between Indigenous and Non-Indigenous Australians. To address this, it is vital to understand key health priorities and knowledge gaps in the current landscape of clinical trial activity focusing on Indigenous health in Australia. METHODS: Australian-based clinical trials registered on the Australian New Zealand Clinical Trials Registry or ClinicalTrials.gov from 2008 to 2018 were analysed. Australian clinical trials with and without a focus on Indigenous health were compared in terms of total numbers, participant size, conditions studied, design, intervention type and funding source. RESULTS: Of the 9206 clinical trials included, 139 (1.5%) focused on Indigenous health, with no proportional increase in Indigenous trials over the decade (p = 0.30). Top conditions studied in Indigenous-focused trials were mental health (n = 35, 28%), cardiovascular disease (n = 20, 20%) and infection (n = 16, 16%). Compared to General Australian trials, Indigenous-focused trials more frequently studied ear conditions (OR 20.26, 95% CI 10.32-37.02, p < 0.001), infection (OR 3.11, 95% CI 1.88-4.85, p < 0.001) and reproductive health (OR 2.59, 95% CI 1.50-4.15, p < 0.001), and less of musculoskeletal conditions (OR 0.09, 95% CI 0.00-0.37, p < 0.001), anaesthesiology (OR 0.16, 95% CI 0.01-0.69, p = 0.021) and surgery (OR 0.17, 95% CI 0.01-0.73, p = 0.027). For intervention types, Indigenous trials focused more on prevention (n = 48, 36%) and screening (n = 18, 13%). They were far less involved in treatment (n = 72, 52%) as an intervention than General Australian trials (n = 6785, 75%), and were less likely to be blinded (n = 48, 35% vs n = 4273, 47%) or have industry funding (n = 9, 7% vs 1587, 17%). CONCLUSIONS: Trials with an Indigenous focus differed from General Australian trials in the conditions studied, design and funding source. The presented findings may inform research prioritisation and alleviate the substantial burden of disease for Indigenous population.

In Situ Raman Observation of Oxygen Activation and Reaction at Platinum-Ceria Interfaces during CO Oxidation.

Understanding the fundamental insights of oxygen activation and reaction at metal-oxide interfaces is of significant importance yet remains a major challenge due to the difficulty in in situ characterization of active oxygen species. Herein, the activation and reaction of molecular oxygen during CO oxidation at platinum-ceria interfaces has been in situ explored using surface-enhanced Raman spectroscopy (SERS) via a borrowing strategy, and different active oxygen species and their evolution during CO oxidation at platinum-ceria interfaces have been directly observed. In situ Raman spectroscopic evidence with isotopic exchange experiments demonstrate that oxygen is efficiently dissociated to chemisorbed O on Pt and lattice Ce-O species simultaneously at interfacial Ce3+ defect sites under CO oxidation, leading to a much higher activity at platinum-ceria interfaces compared to that at Pt alone. Further in situ time-resolved SERS studies and density functional theory simulations reveal a more efficient molecular pathway through the reaction between adsorbed CO and chemisorbed Pt-O species transferred from the interfaces. This work deepens the fundamental understandings on oxygen activation and CO oxidation at metal-oxide interfaces and offers a sensitive technique for the in situ characterization of oxygen species under working conditions.

Design of a noble-metal-free direct Z-scheme photocatalyst for overall water splitting based on a SnC/SnSSe van der Waals heterostructure.

Semiconductor photocatalysts, using sunlight to stimulate various photocatalytic reactions, are promising materials for solving the energy crisis and environmental problems. However, the low photocatalytic efficiency and high cost pose major challenges for their widespread application. Mimicking the natural photosynthesis system, we propose a direct Z-scheme photocatalyst based on a Janus van der Waals heterostructure (vdWH) comprising SnC and Janus SeSnS monolayers. From first-principles calculations, the intrinsic built-in electric field of Janus SeSnS and the charge transfer from the SnC to the SeSnS layer give rise to a type-II band alignment. Such a band alignment benefits the formation of spatially separated reductive and oxidative active sites and the reduction of the global bandgap of the Janus vdWH. The proposed material increases the solar-to-hydrogen conversion efficiency to 60.8%. Besides, we also find that the light absorption coefficient is stacking configuration controllable and strain-tunable, e.g., the tensile strain promotes photocatalytic efficiency. Moreover, because Sn, S, and Se are environmentally benign and inexpensive elements, SnC/SeSnS vdWH is a promising noble-metal-free direct Z-scheme photocatalyst.

High mobility and enhanced photoelectric performance of two-dimensional ternary compounds NaCuX (X = S, Se, and Te).

Two-dimensional (2D) materials have attracted great interest in the field of optoelectronics in recent years due to their atomically thin structure and various electronic properties. Based on the first-principles calculations combined with the non-equilibrium Green's function (NEGF) method, we predict a set of new 2D ternary materials, sodium copper chalcogenides (NaCuX, X = S, Se, and Te). These materials not only have direct band gaps ranging from 1.2 to 1.6 eV, but also possess relatively small carrier effective masses (0.1-0.2m0) at the band edges thus high carrier mobilities (103-104 cm2 V-1 s-1), which collectively imply that they are suitable for optical-electronic applications in the visible (even in the infrared) light region. Moreover, based on the high photo responsivity (Rph), e.g., up to 0.105 A W-1 for NaCuTe, we design a series of NaCuX monolayer based high performance optoelectronic junctions. These properties indicate that NaCuX monolayers are promising candidate materials for photodetectors and photovoltaic units.