Grain Boundary Tailors the Local Chemical Environment on Iridium Surface for Alkaline Electrocatalytic Hydrogen Evolution.

Even though grain boundaries (GBs) have been previously employed to increase the number of active catalytic sites or tune the binding energies of reaction intermediates for promoting electrocatalytic reactions, the effect of GBs on the tailoring of the local chemical environment on the catalyst surface has not been clarified thus far. In this study, a GBs-enriched iridium (GB-Ir) was synthesized and examined for the alkaline hydrogen evolution reaction (HER). Operando Raman spectroscopy and density functional theory (DFT) calculations revealed that a local acid-like environment with H3 O+ intermediates was created in the GBs region owing to the electron-enriched surface Ir atoms at the GBs. The H3 O+ intermediates lowered the energy barrier for water dissociation and provided enough hydrogen proton to promote the generation of hydrogen spillover from the sites at the GBs to the sites away from the GBs, thus synergistically enhancing the hydrogen evolution activity. Notably, the GB-Ir catalyst exhibited a high alkaline HER activity (10 mV @ 10 mA cm-2 , 20 mV dec-1 ). We believe that our findings will promote further research on GBs and the surface science of electrochemical reactions.

Substantial Impact of Built-in Electric Field and Electrode Potential on the Alkaline Hydrogen Evolution Reaction of Ru-CoP Urchin Arrays.

Although great efforts on the delicate construction of a built-in electric field (BIEF) to modify the electronic properties of active sites have been conducted, the substantial impact of BIEF coupled with electrode potential on the electrochemical reactions has not been clearly investigated. Herein, we designed an alkaline hydrogen evolution reaction (HER) catalyst composed of heterogeneous Ru-CoP urchin arrays on carbon cloth (Ru-CoP/CC) with a strong BIEF with the guidance of density functional theory (DFT) calculations. Impressively, despite its unsatisfactory activity at 10 mA cm-2 (overpotential of 44 mV), Ru-CoP/CC exhibited better activity (357 mV) than the benchmark Pt/C catalyst (505 mV) at 1 A cm-2 . Experimental and theoretical studies revealed that strong hydrogen adsorption on the interfacial Ru atoms created a high energy barrier for hydrogen desorption and spillover, resulting in unsatisfactory activity at low current densities. However, as the electrode potential became more negative (i.e., the current density increased), the barrier for hydrogen spillover from the interfacial Ru to the Co site, which had near-zero hydrogen adsorption energy, significantly decreased, thus greatly accelerating the whole alkaline HER process. This explains why the activity of Ru-CoP is relatively susceptible to the electrode potential compared to Pt/C.

Constructing Interfacial Oxygen Vacancy and Ruthenium Lewis Acid-Base Pairs to Boost the Alkaline Hydrogen Evolution Reaction Kinetics.

Simultaneous optimization of the energy level of water dissociation, hydrogen and hydroxide desorption is the key to achieving fast kinetics for the alkaline hydrogen evolution reaction (HER). Herein, the well-dispersed Ru clusters on the surface of amorphous/crystalline CeO2-δ (Ru/ac-CeO2-δ ) is demonstrated to be an excellent electrocatalyst for significantly boosting the alkaline HER kinetics owing to the presence of unique oxygen vacancy (VO ) and Ru Lewis acid-base pairs (LABPs). The representative Ru/ac-CeO2-δ exhibits an outstanding mass activity of 7180 mA mgRu -1 that is approximately 9 times higher than that of commercial Pt/C at the potential of -0.1 V (V vs RHE) and an extremely low overpotential of 21.2 mV at a geometric current density of 10 mA cm-2 . Experimental and theoretical studies reveal that the VO as Lewis acid sites facilitate the adsorption of H2 O and cleavage of H-OH bonds, meanwhile, the weak Lewis basic Ru clusters favor for the hydrogen desorption. Importantly, the desorption of OH from VO sites is accelerated via a water-assisted proton exchange pathway, and thus boost the kinetics of alkaline HER. This study sheds new light on the design of high-efficiency electrocatalysts with LABPs for the enhanced alkaline HER.

Boosting Hydrogen Evolution Reaction by Phase Engineering and Phosphorus Doping on Ru/P-TiO2.

Synergistic optimization of the elementary steps of water dissociation and hydrogen desorption for the hydrogen evolution reaction (HER) in alkaline media is a challenge. Herein, the Ru cluster anchored on a trace P-doped defective TiO2 substrate (Ru/P-TiO2 ) was synthesized as an electrocatalyst for the HER; it exhibited a commercial Pt/C-like geometric activity and an excellent mass activity of 9984.3 mA mgRu -1 at -0.05 V vs. RHE, which is 34.3 and 18.7 times higher than that of Pt/C and Ru/TiO2 , respectively. Experimental and theoretical studies indicated that using a rutile-TiO2 -crystal-phase substrate enhanced the HER activity more than the anatase phase. Rich surface oxygen vacancies on rutile-TiO2 facilitated the adsorption and dissociation of water, while the partial substitution of Ti4+ with P5+ enhanced H2 generation by facilitating hydrogen spillover from the Ru site to the surface P site, synergistically enhancing the HER activity.

Sodium-Decorated Amorphous/Crystalline RuO2 with Rich Oxygen Vacancies: A Robust pH-Universal Oxygen Evolution Electrocatalyst.

The oxygen evolution reaction (OER) is a key reaction for many electrochemical devices. To date, many OER electrocatalysts function well in alkaline media, but exhibit poor performances in neutral and acidic media, especially the acidic stability. Herein, sodium-decorated amorphous/crystalline RuO2 with rich oxygen vacancies (a/c-RuO2 ) was developed as a pH-universal OER electrocatalyst. The a/c-RuO2 shows remarkable resistance to acid corrosion and oxidation during OER, which leads to an extremely high catalytic stability, as confirmed by a negligible overpotential increase after continuously catalyzing OER for 60 h at pH=1. Besides, a/c-RuO2 also exhibits superior OER activities to commercial RuO2 and most reported OER catalysts under all pH conditions. Theoretical calculations indicated that the introduction of Na dopant and oxygen vacancy in RuO2 weakens the adsorption strength of the OER intermediates by engineering the d-band center, thereby lowering the energy barrier for OER.

The Heterostructure of Ru2 P/WO3 /NPC Synergistically Promotes H2 O Dissociation for Improved Hydrogen Evolution.

Facilitating the dissociation of water and desorption of hydrogen are both crucial challenges for improving the hydrogen evolution reaction (HER) in alkaline media. Herein, we report the synthesis of heterostructure of Ru2 P/WO3 @NPC (N, P co-doped carbon) by a simple hydrothermal reaction using ruthenium and tungsten salts as precursors, followed by pyrolyzing under an Ar atmosphere. The Ru2 P/WO3 @NPC electrocatalyst exhibits an outstanding HER activity with an overpotential of 15 mV at a current density of 10 mA cm-2 and excellent durability in a 1.0 M KOH solution, outperforming state-of-the-art Pt/C and most reported electrocatalysts. Experimental results combined with density functional calculations reveal that the electron density redistribution in Ru2 P/WO3 @NPC is achieved by electron transfer from NPC to Ru2 P/WO3 and from Ru2 P to WO3 , which directly promotes the dissociation of water on W sites in WO3 and desorption of hydrogen on Ru sites in Ru2 P.

Upregulation of MALAT-1 and its association with survival rate and the effect on cell cycle and migration in patients with esophageal squamous cell carcinoma.

The aim of this study is to investigate whether metastasis-associated lung adenocarcinoma transcript 1 (MALAT-1) can be used as a potential therapy target for human esophageal squamous cell carcinoma. MALAT-1 expression levels were detected in 137 paired EC samples and adjacent nonneoplastic tissues. Human esophageal carcinoma cell lines EC9706 and KYSE150 were transfected with MALAT-1 small interference RNA. Cell proliferation, migration/invasion ability, cell cycle, and apoptosis were assessed. MALAT-1 expressed higher levels in esophageal cancer tissues when compared with paired adjacent normal tissues. This high expression was associated with a decreased survival rate. MALAT-1 knockdown induced a decrease in proliferation-enhanced apoptosis, inhibited migration/invasion, and reduced colony formation and led to cell cycle arrest at the G2/M phase. These data indicates that MALAT-1 could be exploited for therapeutic benefit.

Two-dimensional GeS with tunable electronic properties via external electric field and strain.

Experimentally, GeS nanosheets have been successfully synthesized using vapor deposition processes and the one-pot strategy. Quite recently, GeS monolayer, the isoelectronic counterpart of phosphorene, has attracted much attention due to promising properties. By means of comprehensive first-principles calculations, we studied the stability and electronic properties of GeS monolayer. Especially, electric field and in-plane strain were used to tailor its electronic band gap. Upon applying electric field, the band gap of GeS monolayer greatly reduces and a semiconductor-metal transition happens under the application of a certain external electric field. Our calculations reveal that the band gaps of GeS monolayer are rather sensitive to the external electric field. On the other hand, for GeS under external strain, quite interestingly, we found that the band gap presents an approximately linear increase not only under compression strain but also under tensile strain from -10% to 10%. For biaxial compressive and tensile strains, the band gap follows the same trend as that of the uniaxial in the zigzag x direction. The present results provide a simple and effective route to tune the electronic properties of GeS monolayer over a wide range and also facilitate the design of GeS-based two-dimensional devices.

[Analysis of prognostic factors in patients with recurrent and metastatic esophageal carcinoma].

OBJECTIVE: The aim of this study was to explore the influencing factors of prognosis for recurrent and metastatic esophageal carcinoma, and to provide reference for clinical treatment for these patients. METHODS: The clinicopathological and follow-up data of 247 patients with recurrent and metastatic esophageal squamous cell carcinoma after radical resection were retrospectively reviewed, combined with analysis of prognostic factors in these patients. Kaplan-Meier method was used to analyze the survival, difference between groups was compared by Log rank test, and Cox model was used for multivariate analysis. RESULTS: Among the 247 recurrent and metastatic patients, locoregional recurrence was in 139 patients (56.3%), distant metastasis in 60 patients (24.3%), and combined recurrence in 48 patients (19.4%). The survival time was 1 to 42 months in the 247 patients, and the median survival time was 10 months. The 1-, 3- and 5-year survival rate after recurrence and metastasis was 26.4%, 6.3% and 2.4%, respectively. Univariate analysis indicated that regional lymph node metastasis of the primary tumor, distant lymph node metastasis, clinical staging, interval between operation and recurrence, recurrent and metastatic patterns, and treatment methods after recurrence and metastasis were influencing factors of prognosis (all P<0.05). Cox multivariate analysis indicated that clinical staging of the primary tumor, interval between operation and recurrence, recurrent and metastatic patterns, and treatment methods after recurrence and metastasis were independent factors influencing prognosis (all P<0.05). CONCLUSIONS: The prognosis of patients with recurrent and metastatic esophageal carcinoma is poor, and it is affected by many factors. Comprehensive treatment is effective in prolonging the survival time of the patients.

[Expression of activin A in tissue and serum of patients with esophageal squamous cell carcinoma and its clinical significance].

OBJECTIVE: The aim of this study was to explore the expression of activin A in esophageal squamous cell carcinoma and its clinical significance. METHODS: Immunohistochemical (IHC) staining was used for detecting the expression of tissue activin A in sixty-four patients with esophageal squamous cell carcinoma, and enzyme-linked immunosorbent assay (ELISA) was used for detecting the serum activin A in the patients before and after surgery. The relationship between expression of activin A in the esophageal cancer tissue with clinicopathological features and its influence on prognosis were analyzed. RESULTS: The positive expression rate of activin A in esophageal squamous cell carcinoma was 82.8% (53/64), and that of normal esophageal epithelium was 6.7% (2/30), showing a very significant difference between them (P < 0.001). Expression of activin A was correlated with both lymph node metastasis and invasion depth of the tumor (all P < 0.05), and the expression of activin A was positively correlated with lymph node metastasis (r = 0.321, P < 0.05) and invasion depth of the tumor (r = 0.417, P < 0.05). The serum activin A of the patients before and after surgery was (911 ± 276) pg/ml and (667 ± 236) pg/ml, respectively, showing a significant difference (P = 0.005). Univariate and multivariate analyses indicated that expression of activin A and lymph node metastasis were independent influencing factors for prognosis in patients with esophageal squamous cell carcinoma (all P < 0.05). CONCLUSIONS: Activin A may play an important role in the pathogenesis and development of esophageal squamous cell carcinoma, and it has an important reference value in the estimation of diagnosis and prognosis for esophageal squamous cell carcinoma.

Competition between Lattice Oxygen and Adsorbate Evolving Mechanisms in Rutile Ru-Based Oxide for the Oxygen Evolution Reaction.

The oxygen evolution reaction (OER) is the primary bottleneck for electrochemical splitting of water into H2. Developing robust and active OER electrocatalysts through understanding the OER mechanism is essential. However, the mechanism for OER is not yet well understood even for the most studied rutile Ru-based oxide, especially in a water-solvent environment. It is still disputed whether the adsorbate evolving mechanism (AEM) is competitive with the lattice oxygen mechanism (LOM). In this article, the AEM and LOM for OER in transition metal (TM)-doped rutile RuO2 with different ratios of TM and Ru are discussed through density functional theory + U calculation. In low TM doping concentration, the evolved O2 is generated through the AEM, and the OER activity is limited by the scaling relationship of OER intermediates. In higher TM doping concentration, the evolved O2 is generated through the LOM for Cu- or Ni-doped RuO2. We find that the distribution of Ru 4d and O 2p orbitals and the adsorption energy of H and O are the major factors that affect the conversion of AEM into LOM. By explicitly considering the water-solvent environment, the LOM can result in higher theoretical OER activity arising from the effects of hydrogen-bond networks.

In Situ Activation Endows Orthorhombic Fluorite-Type Samarium Iridium Oxide with Enhanced Acidic Water Oxidation.

Developing electrochemical catalysts for acidic water oxidation with improved activity and stability has been the key to the further popularization of proton exchange membrane electrolyzers. In this work, an orthorhombic fluorite-type samarium iridium oxide (Sm3IrO7) catalyst is synthesized by a simple solid-state reaction. After in situ activation, the as-prepared Sm3IrO7 exhibits higher mass activity and durability than that of commercial IrO2. The in-depth analyses indicate the formation of amorphous IrOx species on the surface to evolve to a new heterostructure IrOx/Sm3IrO7, along with Sm leaching during the in situ activation process. More importantly, strong electronic interactions exist between newborn IrOx species and remaining Sm3IrO7, leading to the compressed Ir-O bonds in IrOx compared to commercial IrO2, thus reducing the energy barrier for oxygen evolution reaction (OER) intermediates to improve the OER process. Based on the above-mentioned analyses, it is speculated that the actual active species for enhanced acidic water oxidation should be IrOx/Sm3IrO7, rather than Sm3IrO7 itself. Theoretical calculations confirm that the optimal energy level path of IrOx/Sm3IrO7 follows the lattice oxygen mechanism, and the energy level of surface Ir 5d orbitals is lower than O 2p orbitals in IrOx/Sm3IrO7, enabling it a superior OER activity.

The synergistic effect of Hf-O-Ru bonds and oxygen vacancies in Ru/HfO2 for enhanced hydrogen evolution.

Ru nanoparticles have been demonstrated to be highly active electrocatalysts for the hydrogen evolution reaction (HER). At present, most of Ru nanoparticles-based HER electrocatalysts with high activity are supported by heteroatom-doped carbon substrates. Few metal oxides with large band gap (more than 5 eV) as the substrates of Ru nanoparticles are employed for the HER. By using large band gap metal oxides substrates, we can distinguish the contribution of Ru nanoparticles from the substrates. Here, a highly efficient Ru/HfO2 composite is developed by tuning numbers of Ru-O-Hf bonds and oxygen vacancies, resulting in a 20-fold enhancement in mass activity over commercial Pt/C in an alkaline medium. Density functional theory (DFT) calculations reveal that strong metal-support interaction via Ru-O-Hf bonds and the oxygen vacancies in the supported Ru samples synergistically lower the energy barrier for water dissociation to improve catalytic activities.

Exploring the Dominant Role of Atomic- and Nano-Ruthenium as Active Sites for Hydrogen Evolution Reaction in Both Acidic and Alkaline Media.

Ru nanoparticles (NPs) and single atoms (SAs)-based materials have been investigated as alternative electrocatalysts to Pt/C for hydrogen evolution reaction (HER). Exploring the dominant role of atomic- and nano-ruthenium as active sites in acidic and alkaline media is very necessary for optimizing the performance. Herein, an electrocatalyst containing both Ru SAs and NPs anchored on defective carbon (RuSA+NP /DC) has been synthesized via a Ru-alginate metal-organic supramolecules conversion method. RuSA+NP /DC exhibits low overpotentials of 16.6 and 18.8 mV at 10 mA cm-2 in acidic and alkaline electrolytes, respectively. Notably, its mass activities are dramatically improved, which are about 1.1 and 2.4 times those of Pt/C at an overpotential of 50 mV in acidic and alkaline media, respectively. Theoretical calculations reveal that Ru SAs own the most appropriate H* adsorption strength and thus, plays a dominant role for HER in acid electrolyte, while Ru NPs facilitate the dissociation of H2 O that is the rate-determining step in alkaline electrolyte, leading to a remarkable HER activity.

Downregulation of microRNA-382 is associated with poor outcome of esophageal squamous cell carcinoma.

AIM: To study the potential prognostic role of microRNA-382 (miR-382) in esophageal squamous cell carcinoma (ESCC). METHODS: Forty six patients were divided into 2 groups according to postoperative survival time: the poor outcome group (28 patients), who showed early metastasis but no recurrence, and died within 1 year after surgery, 12 patients of the group received postoperative chemotherapy treatment that was given after early metastasis happening; the good outcome group (18 patients), who had no clinical metastasis and recurrence, and survived 5 years or more after surgery, all patients did not receive any postoperative treatment. Total RNA was extracted from the patients' formalin-fixed and paraffin-embedded esophageal cancer tissues. miR-382 level was evaluated using high-throughput real-time quantitative polymerase chain reaction analysis. The correlation between miR-382 level and clinicopathologic features was analyzed through COX regression model, and Kaplan-Meier analysis was used to analyze the relationship between miR-382 level and patient survival time. RESULTS: miR-382 was differentially expressed in the two groups. Overall the average miR-382 level in the ESCC patients with good outcome was 9.8 ± 3.8, while miR-382 level in the ESCC patients with poor outcome was 3.0 ± 0.8. The differences of miR-382 levels between two groups were significant (P < 0.05). Kaplan-Meier analysis results showed that miR-382 expression level generally had a significant reverse-correlation with ESCC patient survival time (P < 0.001), in which the patients with higher expressions of miR-382 had a longer survival time either among individuals with the same tumor stage or among the overall patients. CONCLUSION: miR-382 levels are reverse-correlated with ESCC poor outcomes, suggesting that miR-382 could be a potential predictive biomarker for both prognosis and treatment of ESCC.

Association of p53 expression with prognosis in patients with esophageal squamous cell carcinoma.

It has been well accepted that p53 overexpression is associated with advanced stages of cancer. However, the prognostic role of p53 overexpression in esophageal squamous cell carcinoma (ESCC) remains unclear. To investigate the prognostic role of p53 overexpression in patients with ESCC, a retrospective cohort study of 136 ESCC patients was carried out. The expression of p53 protein in tumor tissues was investigated immunohistochemically. Positive expression of p53 protein was detected in 57 ESCC patients (41.9%). The p53 overexpression was associated with smoking (P < 0.001), tumor differentiation (P < 0.001), and tumor size (P < 0.001). In the Kaplan-Meier analysis, patients with p53 overexpression had significantly shorter overall survival than those patients with negative p53 expression (log-rank P < 0.001). Multivariable analysis by Cox regression model further showed that p53 overexpression was a significantly independent predictor of poorer overall survival (hazard ratio [HR] = 1.91; 95% confidence interval [95% CI] 1.03-3.54, P = 0.04). Thus, p53 overexpression is associated with poor prognosis in patients with early stage esophageal squamous cell carcinoma, and it's a significantly independent predictor of poorer overall survival.

Screening of microRNA in patients with esophageal cancer at same tumor node metastasis stage with different prognoses.

Patients at the same pathological stage of esophageal cancer (EC) that received the same surgical therapy by the same surgeon may have distinct prognoses. The current study aimed to explore the possibility of differentially- expressed microRNAs (miRNAs) underlying this phenomenon. Samples were collected from EC patients at the same tumor node metastasis (TNM) stage but with different prognoses. Paracancerous normal tissues were taken as controls. The specimens were histopathologically analyzed. Differentially-expressed miRNAs were analyzed using real-time quantitative reverse transcription polymerase chain reaction. Compared with patients with poor prognosis, those with good prognosis exhibited 88 two-fold or more than two-fold increased miRNA fragments and 4 half-decreased miRNAs. The most noticeably up-regulated miRNAs included hsa-miR-31, hsa-miR- 196b, hsa-miR-652, hsa-miR-125a-5p, hsa-miR-146b, hsa-miR-200c, hsa-miR-23b, hsa-miR-29a, hsa-miR-186, hsa-miR-205, hsa-miR-376a, hsa-miR-410, hsa-miR-532-3p, and hsa-miR-598, whereas the most significantly- downregulated miRNAs were hsa-let-7e, hsa-miR-130b, and hsa-miR-103. EC patients at same TNM stage but with different prognoses show differentially-expressed miRNAs.

Differential expression of miRNAs in esophageal cancer tissue.

The aim of this study was to explore the association of specific microRNAs (miRNAs) with the development of esophageal cancer (EC) and to identify new molecular markers for EC by analyzing the expression profiles of miRNAs in EC tissues. The expression profiles of miRNAs in paired EC and paracancerous normal tissues were detected and bioinformatically analyzed using miRNA assays. The outcomes were validated using real-time polymerase chain reaction. The miRNA assays revealed a total of 60 differentially expressed miRNAs in the EC tissues compared with those in the paracancerous normal tissues. Among them, 51 had doubled or more than doubled their expression levels and 9 had halved their expression levels. The most markedly upregulated miRNAs were hsa-miR-15a, hsa-miR-28-3p, hsa-miR-31, hsa-miR-99b, hsa-miR-101, hsa-miR-130a, hsa-miR-143, hsa-miR-196b, hsa-miR-200a, hsa-miR-210, hsa-miR-452 and hsa-miR-27a, whereas the most markedly downregulated miRNAs included hsa-miR-30b, hsa-miR-223, hsa-miR-454, hsa-miR-486, hsa-miR-574-3p and hsa-miR-126. Specific miRNA expression profiles exist in EC tissues and may serve as novel EC molecular markers.

Involvement of microRNA-198 overexpression in the poor prognosis of esophageal cancer.

OBJECTIVE: This study aimed to investigate whether the miR-198 expression level is related to clinicopathological factors and prognosis of esophageal cancer. METHODS: MicroRNA was extracted from esophageal cancer patients who underwent surgery for assessment using the Taqman@ MicroRNA assay. The correlation between miR-198 expression and clinicopathological features was analyzed, and the significance of miR-198 as a prognostic factor and its relationship with survival was determined. RESULTS: MicroRNA-198 (miR-198) expression was higher in patients with poor prognosis than those with good prognosis (P < 0.05). Kaplan-Meier analysis results showed that the miR-198 expression level had a significant correlation with survival time (P = 0.030) and that patients with a higher expression of miR-198 had a shorter survival time. Cox multi-factor model analysis showed that patient prognosis (P = 0.014), tumor length (P = 0.040) and expression (P = 0.012), and survival time had a significant correlation; the corresponding risks were 7.268, 1.246, and 3.524, respectively. CONCLUSION: miR- 198 overexpression is involved in the poor prognosis of esophageal cancer and can be used as a biomarker for selection of cases requiring especial attention.