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To establish a risk-scoring system for lymph node metastasis (LNM) of early-stage endometrial carcinoma (EC), and to stratify the preoperative risk of LNM.We retrospectively analyzed the clinical data of 507 patients diagnosed with the early-stage EC (i.e., confined to the uterine corpus). We determined the risk factors for LNM by logistic regression analysis; then constructed a simple logistic scoring system, and an additive scoring system based on the regression coefficient (β), and odds ratio, of each variable, respectively.The overall rate of LNM was 9.1% (46/507). Multivariate analysis showed that preoperative serum cancer antigen 125 (CA125) ≥35 U/mL, histopathology of grade 3 and/or type II, depth of myometrial invasion ≥1/2 and positive immunostaining for Ki-67 ≥50%, were independent risk factors for LNM (P 0.05). The simple logistic and additive scoring systems exhibited good predictive ability (area under the curve [AUC]0.8). Based on the additive scoring system, the risk of LNM in patients with early-stage EC was classified into three groups: a low-risk group (total score:5), an intermediate-risk group (total score: 5-10) and a high-risk group (total score:10). The incidence of LNM differed significantly across these three groups (P 0.05).The risk-scoring system constructed in this study can effectively predict the risk of LNM in patients with early-stage EC, achieve preoperative risk stratification and provide a reference guideline for the use of lymphadenectomy.

We are concerned with the time-asymptotic behavior toward rarefaction waves for strong non-vacuum solutions to the Cauchy problem of the one-dimensional compressible Navier-Stokes equations with degenerate density-dependent viscosity. The case when the pressure p ( ρ ) = ρ γ and the viscosity coefficient μ ( ρ ) = ρ α for some parameters α , γ ∈ R is considered. For α ≥ 0 , γ ≥ max ⁡ { 1 , α } , if the initial data is assumed to be sufficiently regular, without vacuum and mass concentrations, we show that the Cauchy problem of the one-dimensional compressible Navier-Stokes equations admits a unique global strong non-vacuum solution, which tends to the rarefaction waves as time goes to infinity. Here both the initial perturbation and the strength of the rarefaction waves can be arbitrarily large. The proof is established via a delicate energy method and the key ingredient in our analysis is to derive the uniform-in-time positive lower and upper bounds on the specific volume.

The underlying mechanism of post-operative relapse of non-small cell lung cancer (NSCLC) remains poorly understood. We enrolled 57 stage I NSCLC patients with or without relapse and performed whole-exome sequencing (WES) and RNA sequencing (RNA-seq) on available primary and recurrent tumors, as well as on matched tumor-adjacent tissues (TATs). The WES analysis revealed that primary tumors from patients with relapse were enriched with USH2A mutation and 2q31.1 amplification. RNA-seq data showed that the relapse risk was associated with aberrant immune response and metabolism in the microenvironment of primary lesions. TATs from the patients with relapse showed an immunosuppression state. Moreover, recurrent lesions exhibited downregulated immune response compared with their paired primary tumors. Genomic and transcriptomic features were further subjected to build a prediction model classifying patients into groups with different relapse risks. We show that the recurrence risk of stage I NSCLC could be ascribed to the altered immune and metabolic microenvironment. TATs might be affected by cancer cells and facilitate the invasion of tumors. The immune microenvironment in the recurrent lesions is suppressed. Patients with a high risk of relapse need active post-operative intervention.

Objectives. The causes of ovarian cancer (OC) have been confirmed to be closely related to genetic factors. Identifying sequence variants of hereditary ovarian cancer (HOC) susceptibility genes can increase clinical surveillance, facilitate early detection, and provide personalized treatment for patients. This study is aimed at investigating the variation frequency of HOC susceptibility genes in the Chinese population and providing information for the etiology and genetics of OC. Methods. 118 epithelial OC patients were recruited in this clinical study. Variants of 18-gene panel were detected in blood samples by next-generation sequencing (NGS) technology. Results. Overall, 36.44% (43/118) of patients carried at least one pathogenic variant. Among these, BRCA1 pathogenic variants were detected in 31 (26.27%) patients, and 5 (4.24%) patients carried pathogenic variants of BRCA2. Moreover, 27.12% (32/118) of patients carried variants of unknown significance (VUSs). Importantly, we detected eight variants that were not reported previously. Conclusions. Our study enlarged the spectrum of HOC-associated gene sequence variants in the Chinese population and also proved the necessity of multigene testing in epithelial OC patients. The identification of patients with HOC will allow family members to undergo cascade testing where identification of unaffected carriers can facilitate early detection, risk reduction, or prevention of OC and ultimately improve long-term outcomes.

This paper is concerned with the large-time behavior of solutions to the Cauchy problem of the one-dimensional compressible fluid models of Korteweg type with density- and temperature-dependent viscosity, capillarity, and heat conductivity coefficients, which models the motions of compressible viscous fluids with internal capillarity. We show that the combination of a viscous contact wave with two rarefaction waves is asymptotically stable with a large initial perturbation if the strength of the composite wave and the capillarity coefficient satisfy some smallness conditions. The proof is based on some refined L 2-energy estimates to control the possible growth of the solutions caused by the high nonlinearity of the system, the interactions of waves from different families and large data, and the key ingredient is to derive the uniform positive lower and upper bounds on the specific volume and the temperature.

This paper is concerned with the time-asymptotic behavior of strong solutions to an initial-boundary value problem of the compressible Navier-Stokes-Korteweg system on the half line $\mathbb{R}^+$. The asymptotic profile of the problem is shown to be a shifted viscous shock profile, which is suitably away from the boundary. Moreover, we prove that if the initial data around the shifted viscous shock profile and the strength of the shifted viscous shock profile are sufficiently small, then the problem has a unique global strong solution, which tends to the shifted viscous shock profile as time goes to infinity. The analysis is based on the elementary $L^2$-energy method and the key point is to deal with the boundary estimates.

Nitrogen-doped biochars derived from Phragmites australis (PA) were prepared using ammonium chloride (AC) and ammonium acetate (AA) as nitrogen sources by phosphoric acid activation via microwave assisted treatment. Their physicochemical properties, acid red 18 (AR18) adsorption performance and possible mechanisms were systematically evaluated. Nitrogen was successfully doped onto the biochar’s surface in the formation of pyrrole-N, pyridine-N and oxidized-N with pyridine-N being the major component (64%). The pH iep and basic foundational groups of the biochars increased consequently however their surface areas slightly decreased. The adsorption kinetic data were best fit to the pseudo-second order model and the equilibrium data were well simulated by Freundlich model for all biochars, indicating the important role of chemical interactions. The maximum AR18 adsorption capacities of PAB-AA and PAB-AC were 1.41 and 1.18 times higher compared with the non N-doped biochar, which were mainly attributed to the π-π EDA interaction between the pyridine-N and AR18 as revealed by the comparison of XPS analyses before and after AR18 adsorption. Meanwhile, other mechanisms such as pore filling effect, Lewis acid-base interaction, electrostatic attraction and hydrogen bonding also existed as demonstrated by BET, XPS and FTIR analyses.

Three organic acid ammoniums (ammonium succinate (AS), ammonium tartrate (AT) and ammonium citrate (AC)) were employed to modify Phragmites australis (PA)-based activated carbons during phosphoric acid activation via microwave irradiation to improve acid red 18 (AR 18) removals from aqueous solutions. The physicochemical properties of the modified (PAC-AS, PAC-AT and PAC-AC) and unmodified carbons (PAC) were systematically characterized. The nitrogen content, pHiep and basic foundational groups of the modified carbons increased however their surface areas decreased after modification. FTIR and XPS analyses revealed that N-containing groups such as NH, CONH and NH2 were effectively introduced on modified carbons' surfaces. Although PAC-AS and PAC-AT had lower surface area than PAC, their adsorption capacity were higher due to larger amount of N-containing groups. The adsorption kinetic data were simulated well by the Elovich equation and the equilibrium data were best fit to the Freundlich model for all PACs. The adsorption of AR 18 on PACs decreased with increasing pH values. The maximum AR 18 adsorption capacity followed an order of PAC-AS (115.93 mg/g) > PAC-AT (104.23 mg/g) > PAC (90.52 mg/g) > PAC-AC (57.99 mg/g), indicating that AS and AT are promising activating agents for activated carbons to improve their AR18 adsorption performances.

Electrochemical reduction of CO2 into chemical fuels is crucial to clean energy production and environment remediation. First-principles calculations are performed to elucidate reaction mechanism of CO2 reduction to formic acid on Ni-based catalysts. The origin of CO poisoning is examined and a novel design strategy is proposed to eliminate CO poisoning. Three design criteria are derived based on which computational screening is performed to identify several Ni-based near-surface-alloys (NSAs) with both high selectivity and reactivity. The effect of elastic strain on CO2 reduction is studied on these NSAs. We predict that Ni/Ti, Cu/Ni, and strained Cu/Ni NSAs could lead to highly selective and efficient production of formic acid.

First-principles calculations are performed to gain fundamental understanding of recently developed Al/graphite battery that exhibits well-defined discharge voltage plateaus, high cycling stability, and ultrafast rate performance. Crucial issues pertaining to the unprecedented performance of the battery are understood, and key controversies in literature with respect to the geometry and gallery height of the intercalant are resolved. The stage and atomic structure of the graphite intercalation compounds (GICs) are elucidated, in line with the experimental finding. It is revealed that the intercalants tend to be inserted at relative high densities with a charging potential profile and theoretical specific capacity that agree well with the experiment. Four stable GIC configurations are identified with essentially the same chemical potential for the intercalant, giving rise to charging potential plateaus. Low diffusion energy barriers of the intercalants are found, which underlie the ultrafast (dis)charging ...

Tin (Sn) is known to be a good catalyst for electrochemical reduction of CO2 to formate in 0.5 M KHCO3. But when a thin layer of SnO2 is coated over Cu nanoparticles, the reduction becomes Sn-thickness dependent: the thicker (1.8 nm) shell shows Sn-like activity to generate formate whereas the thinner (0.8 nm) shell is selective to the formation of CO with the conversion Faradaic efficiency (FE) reaching 93% at −0.7 V (vs reversible hydrogen electrode (RHE)). Theoretical calculations suggest that the 0.8 nm SnO2 shell likely alloys with trace of Cu, causing the SnO2 lattice to be uniaxially compressed and favors the production of CO over formate. The report demonstrates a new strategy to tune NP catalyst selectivity for the electrochemical reduction of CO2 via the tunable core/shell structure.

A new calcium-modified and starch-stabilized ferromanganese binary oxide (Ca-SFMBO) sorbent was fabricated with different Ca concentrations for the adsorption of arsenic (As) and cadmium (Cd) in water. The maximum As(III) and Cd(II) adsorption capacities of 1% Ca-SFMBO were 156.25 mg/g and 107.53 mg/g respectively in single-adsorption systems. The adsorption of As and Cd by the Ca-SFMBO sorbent was pH-dependent at values from 1 to 7, with an optimal adsorption pH of 6. In the dual-adsorbate system, the presence of Cd(II) at low concentrations enhanced As(III) adsorption by 33.3%, while the adsorption of As(III) was inhibited with the increase of Cd(II) concentration. Moreover, the addition of As(III) increased the adsorption capacity for Cd(II) up to two-fold. Through analysis by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR), it was inferred that the mechanism for the co-adsorption of Cd(II) and As(III) included both competitive and synergistic effects, which resulted from the formation of ternary complexes. The results indicate that the Ca-SFMBO material developed here could be used for the simultaneous removal of As(III) and Cd(II) from contaminated water.

This paper is concerned with the global existence and large time behavior of strong solutions to the Cauchy problem of one-dimensional compressible isentropic micropolar fluid model with density-dependent viscosity and microviscosity coefficients, where the far-fields of the initial data are prescribed to be different. The pressure p ( ρ ) = ρ γ and the viscosity coefficient μ ( ρ ) = ρ α for some parameters α , γ ∈ R are considered. For the case when the corresponding Riemann problem of the resulting Euler equations admits two rarefaction waves solutions, it is shown that if the parameters α and γ satisfy some conditions and the initial data is sufficiently regular, without vacuum and mass concentrations, then the Cauchy problem of the one-dimensional compressible micropolar fluid model has a unique global strong nonvacuum solution, which tends to a superposition of these two rarefaction waves as time goes to infinity. This result holds for arbitrarily large initial perturbation and large-amplitudes rarefaction waves. Moreover, the exponential time decay rate of the microrotation velocity ω ( t , x ) under large initial perturbation is also derived. The proof is given by an elaborate energy method and the key ingredient is to deduce the uniform-in-time lower and upper bounds on the specific volume.

We propose a multiscale computational framework to design core/shell nanoparticles (NPs) for oxygen reduction reaction (ORR). Essential to the framework are linear scaling relations between oxygen adsorption energy and surface strain, which can be determined for NP facets and edges from first-principles and multiscale QM/MM calculations, respectively. Based on the linear scaling relations and a microkinetic model, we can estimate ORR rates as a function of surface strain on core/shell NPs. Employing the multiscale framework, we have systematically examined the ORR activity on Pd-based core/shell NPs as a function of their shape, size, shell thickness, and alloy composition of the core. Three NP shapes—icosahedron, octahedron, and truncated octahedron—are explored, and the truncated octahedron is found to be the most active and the icosahedron is the least active. NixPd1–x@Pd NPs with high Ni concentrations and thin shells could exhibit higher ORR rates than the pure Pt(111) surface and/or Pt NPs. AgxPd1–x...

Surface engineering has proved effective in enhancing activities of CO2 reduction reaction (CO2RR) on Cu. However, predictive guidance is necessary for the surface engineering to reach its full potential. We propose that the generalized coordination number (GCN) can be used as a descriptor to characterize CO2RR on Cu surfaces. A set of linear scaling relations between the binding energy of CO2RR intermediates and GCN are established to construct a volcano-type coordination–activity plot and from which we can derive the theoretical overpotential limit on Cu surfaces. We predict that the dimerized (111) surface yields the lowest possible overpotential on Cu for CO2RR to methane, and surface engineering by creating adatoms could lower CO2RR overpotentials and simultaneously suppress the competing hydrogen evolution reaction.

We consider the large time behavior of a non-autonomous third grade fluid system, which could be viewed as a perturbation of the classical Navier-Stokes system. Under proper assumptions, we firstly prove that the family of processes generated by the problem admits a uniform attractor in the natural phase space. Then we prove the upper-semicontinuity of the uniform attractor when the perturbation tends to zero.

This paper is concerned with the large-time behavior of smooth non-vacuum solutions with large initial data to the Cauchy problem of the one-dimensional isothermal compressible fluid models of Korteweg type with the viscosity coefficient μ ( ρ ) = ρ α and the capillarity coefficient κ ( ρ ) = ρ β . Here α ∈ R and β ∈ R are some parameters. Depending on whether the far-fields of the initial data are the same or not, we prove that the corresponding Cauchy problem admits a unique global smooth solution which tends to constant states or rarefaction waves respectively, as time goes to infinity, provided that α and β satisfy some conditions. Note that the initial perturbation can be arbitrarily large. The proofs are given by the elementary energy method and Kanel’s technique (Kanel, 1968). Compared with former results in this direction obtained by Germain and LeFloch (2016), and Chen et al. (2015), the main novelties of this paper lie in the following: First, we obtain the global existence of smooth solutions with large data for some new varieties of parameters α and β . Second, the large-time behavior of smooth large solutions around constant states is established.

A field study was conducted to investigate the effect of Fe-based biochar application on the extractability and availability of Cd and As, as well as its impact on crop growth and yield under a two-years wheat-rice rotation system. The Fe-based biochar was applied to the soil at 1.5 and 3.0 t ha–1, manure compost was also applied as a comparison, as well as a non-treated control. The application of the Fe-based biochar significantly (p

We are concerned with the large time behavior of solutions to the Cauchy problem of the one-dimensional compressible micropolar fluid model without viscosity, where the far-field states of the initial data are prescribed to be different. If the corresponding Riemann problem of the compressible Euler system admits a contact discontinuity and two rarefaction waves solutions, we show that for such a non-viscous model, the combination of the viscous contact wave with two rarefaction waves is time-asymptotically stable provided that the strength of the composite wave and the initial perturbation are sufficiently small. The proof is given by an elementary $L^2$ energy method., 26pages. arXiv admin note: text overlap with arXiv:1712.09485

This paper is concerned with a singular limit for the one-dimensional compressible radiation hydrodynamics model. The singular limit we consider corresponds to the physical problem of letting the Bouguer number infinite while keeping the Boltzmann number constant. In the case when the corresponding Euler system admits a contact discontinuity wave, Wang and Xie (2011) [12] recently verified this singular limit and proved that the solution of the compressible radiation hydrodynamics model converges to the strong contact discontinuity wave in the L∞-norm away from the discontinuity line at a rate of e 1 4 , as the reciprocal of the Bouguer number tends to zero. In this paper, Wang and Xie's convergence rate is improved to e 7 8 by introducing a new a priori assumption and some refined energy estimates. Moreover, it is shown that the radiation flux q tends to zero in the L∞-norm away from the discontinuity line, at a convergence rate as the reciprocal of the Bouguer number tends to zero.

This paper is concerned with the global existence of classical solutions with large initial data away from vacuum to the Cauchy problem of the one-dimensional isothermal compressible fluid models of Korteweg type with density-dependent viscosity coefficient and capillarity coefficient. The case when the viscosity coefficient μ ( ρ ) = ρ α and the capillarity coefficient κ ( ρ ) = ρ β for some parameters α , β ∈ R is considered. Under some conditions on α , β , we first show the global existence of large solutions around constant states if the far-fields of the initial data are the same, while if the far-fields of the initial data are different, we prove the global stability of rarefaction waves with large strength. Here global stability means the initial perturbation can be arbitrarily large. Our analysis is based on the elementary energy method and the technique developed by Y. Kanel' [29] .

SmMn2O5 mullite has recently been reported to be a promising alternative to traditional Pt-based catalysts for environmental and energy applications. By performing density functional theory calculations, we have systematically investigated lattice oxygen reactivity and oxygen adsorption/dissociation/migration behaviors on low-index surfaces of SmMn2O5 mullite with different terminations. On the basis of the oxygen chemistry and thermodynamic stability of different facets, we conclude that (100)3+, (010)4+, and (001)4+ are reactive toward NO oxidation via either the Mars van Krevelen (MvK) or Eley–Rideal (ER) mechanism. Concrete NO → NO2 reaction paths on these candidate mechanisms have also been calculated. Both the (010)4+ and (001)4+ surfaces presented desirable activities. Bridge MnO sites on (010)4+ surface are identified to be the most active for NO oxidation through the ER mechanism with the lowest barrier of ∼0.38 eV. We have also identified that on all active sites considered in the current study,...

This paper is concerned with the existence and time-asymptotic nonlinear stability of traveling wave solutions to the Cauchy problem of the one-dimensional compressible fluid models of Korteweg type, which governs the motions of the compressible fluids with internal capillarity. The existence of traveling wave solutions is obtained by the phase plane analysis, then the traveling wave solution is shown to be asymptotically stable by the elementary L 2 -energy method.

Based on first-principles calculations, we predict that penta-twinned Cu nanowires (NWs) are superior to conventional Cu catalysts for CO2 electroreduction. The penta-twinned NWs possess a combination of ultrahigh mechanical strength, large surface-to-volume ratios and an abundance of undercoordinated adsorption sites, all desirable for CO2 electroreduction. In particular, we show that the penta-twinned Cu NWs can withstand elastic strains orders of magnitude higher than their conventional counterpart, and as a result their CO2 electroreduction activities can be significantly enhanced by elastic tensile strains. With a moderate tensile strain, the bias potential for methane production at a decent current density (2 mA cm−2) can be reduced by 50%. On the other hand, the competing hydrogen evolution reaction can be suppressed by the tensile strains. The presence of H at the NW surface is found to have a minor effect on CO2 electroreduction. Finally, we propose to use graphene as a substrate to stretch deposited Cu NWs.

The structural, electronic, electrochemical as well as diffusion properties of Na doped phosphorene have been investigated based on first-principles calculations. The strong binding energy between Na and phosphorene indicates that Na could be stabilized on the surface of phosphorene without clustering. By comparing the adsorption of Na atoms on one side and on both sides of phosphorene, it has been found that Na-Na exhibits strong repulsion at the Na-Na distance of less than 4.35 Å. The Na intercalation capacity is estimated to be 324 mA h g(-1) and the calculated discharge curve indicates quite a low Na(+)/Na voltage of phosphorene. Moreover, the diffusion energy barrier of Na atoms on the phosphorene surface at both low and high Na concentrations is as low as 40-63 meV, which implies the high mobility of Na during the charge/discharge process.

A novel 2D structure composed only of carbon and nitrogen elements at the molar ratio of 1 : 1 is predicted by first-principles calculations. The basic structural units are 1,3,5-triazine molecules which trimerize and polymerize into a 2D network of semiconductor nature. Six triazine units comprise a hollow hexagon with a van der Waals hole diameter of about 2.4 A, which is suitable for H2 separation from larger molecules. Metal atoms of various sizes can strongly bind over the polynitrogen pore, which suggests that the 2D network is an ideal support for single-atom catalysis.

The global solutions with large initial data for the isothermal compressible fluid models of Korteweg type has been studied by many authors in recent years. However, little is known of global large solutions to the nonisothermal compressible fluid models of Korteweg type up to now. This paper is devoted to this problem, and we are concerned with the global existence of smooth and non-vacuum solutions with large initial data to the Cauchy problem of the one-dimensional nonisothermal compressible fluid models of Korteweg type. The case when the viscosity coefficient $\mu(\rho)=\rho^\alpha$, the capillarity coefficient $\kappa(\rho)=\rho^\beta$, and the heat-conductivity coefficient $\tilde{\alpha}(\theta)=\theta^\lambda$ for some parameters $\alpha,\beta,\lambda\in \mathbb{R}$ is considered. Under some assumptions on $\alpha,\beta$ and $\lambda$, we prove the global existence and time-asymptotic behavior of large solutions around constant states. The proofs are given by the elementary energy method combined with the technique developed by Y. Kanel' \cite{Y. Kanel} and the maximum principle., Comment: 30pages

Tin (Sn) is known to be a good catalyst for electrochemical reduction of CO

We carry out first-principles simulations to assess the potential of Pd− Cu−Si metallic glasses as catalysts for oxygen reduction reaction (ORR) using oxygen adsorption energy (EO) as a descriptor. We find that the substitution of Cu on crystalline Pd(111) surface improves the ORR activity while the substitution of Si on the surface is in general detrimental to the ORR activity. Compressive strains are found to weaken oxygen binding on the surface and thus enhance the ORR activity. On the basis of the analysis of EO distribution on the Pd metallic glasses surfaces, we find that for Si-deficient adsorption sites, the local ORR activity could exceed that on pure Pd surface, while Si-rich sites exhibit a rather poor ORR activity. The Pd metallic glasses can sustain a much higher compression than the crystalline counterpart, thus their ORR activity can be improved substantially under a large compression. It is predicted that low-Si Pd metallic glasses could be excellent ORR catalysts under compression.

This paper is concerned with the vanishing capillarity–viscosity limit for the one-dimensional compressible Navier–Stokes–Korteweg system to the Riemann solution of the Euler system that consists of the supposition of two rarefaction waves and a contact discontinuity. It is shown that there exists a family of smooth solutions to the compressible Navier–Stokes–Korteweg system which converge to the Riemann solution away from the initial time t = 0 and the contact discontinuity located at x = 0 , as the coefficients of capillarity, viscosity and heat conductivity tend to zero. Moreover, a uniform convergence rate in terms of the above physical parameters is also obtained. Here, the strengths of both the rarefaction waves and the contact discontinuity are not required to be small.

This paper is concerned with the existence, uniqueness, and nonlinear stability of stationary solutions to the Cauchy problem of the full compressible Navier–Stokes–Korteweg system effected by the given mass source, the external force of general form, and the energy source in R 3 . Based on the weighted L 2 -method and some delicate L ∞ estimates on solutions to the linearized problem, the existence and uniqueness of stationary solution are obtained by the contraction mapping principle. The proof of the stability result is given by an elementary energy method and relies on some intrinsic properties of the full compressible Navier–Stokes–Korteweg system.

We report ab initio calculations at the LDA+ U level to examine the atomic configurations and stabilities of different terminations of the perovskite LaCoO 3 . Results of cleavage energies indicate that the propensity to reconstruct depends on the orientation of terminations. The stability of the reconstructed termination relates to the nominal charge of a given surface. O atoms on surfaces interact repulsively with each other. We discuss the thermodynamic stabilities of all terminations using the Grand potential. A stability diagram demonstrates that the ground termination is LaO-(001) p (1 × 1) surface in most cases, while it transforms to the LaO 3 -(111) p (1 × 1) surface in O-rich/La-poor condition. The results provide potential candidates for future studies of LaCoO 3 surface catalysis.