Steering CO2 hydrogenation toward C-C coupling to hydrocarbons using porous organic polymer/metal interfaces.

The conversion of CO2 into fuels and chemicals is an attractive option for mitigating CO2 emissions. Controlling the selectivity of this process is beneficial to produce desirable liquid fuels, but C-C coupling is a limiting step in the reaction that requires high pressures. Here, we propose a strategy to favor C-C coupling on a supported Ru/TiO2 catalyst by encapsulating it within the polymer layers of an imine-based porous organic polymer that controls its selectivity. Such polymer confinement modifies the CO2 hydrogenation behavior of the Ru surface, significantly enhancing the C2+ production turnover frequency by 10-fold. We demonstrate that the polymer layers affect the adsorption of reactants and intermediates while being stable under the demanding reaction conditions. Our findings highlight the promising opportunity of using polymer/metal interfaces for the rational engineering of active sites and as a general tool for controlling selective transformations in supported catalyst systems.

Atomically Dispersed Ru-doped Ti4O7 Electrocatalysts for Chlorine Evolution Reaction with a Universal Activity.

Chlorine has been supplied by the chlor-alkali process that deploys dimensionally stable anodes (DSAs) for the electrochemical chlorine evolution reaction (ClER). The paramount bottlenecks have been ascribed to an intensive usage of precious elements and inevitable competition with the oxygen evolution reaction. Herein, a unique case of Ru2+-O4 active motifs anchored on Magnéli Ti4O7 (Ru-Ti4O7) via a straightforward wet impregnation and mild annealing is reported. The Ru-Ti4O7 performs radically active ClER with minimal deployment of Ru (0.13 wt%), both in 5 m NaCl (pH 2.3) and 0.1 m NaCl (pH 6.5) electrolytes. Scanning electrochemical microscopy demonstrates superior ClER selectivity on Ru-Ti4O7 compared to the DSA. Operando X-ray absorption spectroscopy and density functional theory calculations reveal a universally active ClER (over a wide range of pH and [Cl-]), through a direct adsorption of Cl- on Ru2+-O4 sites as the most plausible pathway, together with stabilized ClO* at low [Cl-] and high pH.

Unlocking the unfolded structure of ubiquitin: Combining time-resolved x-ray solution scattering and molecular dynamics to generate unfolded ensembles.

The unfolding dynamics of ubiquitin were studied using a combination of x-ray solution scattering (XSS) and molecular dynamics (MD) simulations. The kinetic analysis of the XSS ubiquitin signals showed that the protein unfolds through a two-state process, independent of the presence of destabilizing salts. In order to characterize the ensemble of unfolded states in atomic detail, the experimental XSS results were used as a constraint in the MD simulations through the incorporation of x-ray scattering derived potential to drive the folded ubiquitin structure toward sampling unfolded states consistent with the XSS signals. We detail how biased MD simulations provide insight into unfolded states that are otherwise difficult to resolve and underscore how experimental XSS data can be combined with MD to efficiently sample structures away from the native state. Our results indicate that ubiquitin samples unfolded in states with a high degree of loss in secondary structure yet without a collapse to a molten globule or fully solvated extended chain. Finally, we propose how using biased-MD can significantly decrease the computational time and resources required to sample experimentally relevant nonequilibrium states.

Steam-Assisted Selective CO2 Hydrogenation to Ethanol over Ru-In Catalysts.

Multicomponent catalysts can be designed to synergistically combine reaction intermediates at interfacial active sites, but restructuring makes systematic control and understanding of such dynamics challenging. We here unveil how reducibility and mobility of indium oxide species in Ru-based catalysts crucially control the direct, selective conversion of CO2 to ethanol. When uncontrolled, reduced indium oxide species occupy the Ru surface, leading to deactivation. With the addition of steam as a mild oxidant and using porous polymer layers to control In mobility, Ru-In2O3 interface sites are stabilized, and ethanol can be produced with superior overall selectivity (70%, rest CO). Our work highlights how engineering of bifunctional active ensembles enables cooperativity and synergy at tailored interfaces, which unlocks unprecedented performance in heterogeneous catalysts.

Structure and Site Evolution of Framework Ni Species in MIL-127 MOFs for Propylene Oligomerization Catalysis.

A mixed-valence oxotrimer metal-organic framework (MOF), Ni-MIL-127, with a fully coordinated nickel atom and two iron atoms in the inorganic node, generates a missing linker defect upon thermal treatment in helium (>473 K) to engender an open coordination site on nickel which catalyzes propylene oligomerization devoid of any cocatalysts or initiators. This catalyst is stable for ∼20 h on stream at 500 kPa and 473 K, unprecedented for this chemistry. The number of missing linkers on synthesized and activated Ni-MIL-127 MOFs is quantified using temperature-programmed oxidation, 1H nuclear magnetic resonance spectroscopy, and X-ray absorption spectroscopy to be ∼0.7 missing linkers per nickel; thus, a majority of Ni species in the MOF framework catalyze propylene oligomerization. In situ NO titrations under reaction conditions enumerate ∼62% of the nickel atoms as catalytically relevant to validate the defect density upon thermal treatment. Propylene oligomerization rates on Ni-MIL-127 measured at steady state have activation energies of 55-67 kJ mol-1 from 448 to 493 K and are first-order in propylene pressures from 5 to 550 kPa. Density functional theory calculations on cluster models of Ni-MIL-127 are employed to validate the plausibility of the missing linker defect and the Cossee-Arlman mechanism for propylene oligomerization through comparisons between apparent activation energies from steady-state kinetics and computation. This study illustrates how MOF precatalysts engender defective Ni species which exhibit reactivity and stability characteristics that are distinct and can be engineered to improve catalytic activity for olefin oligomerization.

Dynamic Evolution of Palladium Single Atoms on Anatase Titania Support Determines the Reverse Water-Gas Shift Activity.

Research interest in single-atom catalysts (SACs) has been continuously increasing. However, the lack of understanding of the dynamic behaviors of SACs during applications hinders catalyst development and mechanistic understanding. Herein, we report on the evolution of active sites over Pd/TiO2-anatase SAC (Pd1/TiO2) in the reverse water-gas shift (rWGS) reaction. Combining kinetics, in situ characterization, and theory, we show that at T ≥ 350 °C, the reduction of TiO2 by H2 alters the coordination environment of Pd, creating Pd sites with partially cleaved Pd-O interfacial bonds and a unique electronic structure that exhibit high intrinsic rWGS activity through the carboxyl pathway. The activation by H2 is accompanied by the partial sintering of single Pd atoms (Pd1) into disordered, flat, ∼1 nm diameter clusters (Pdn). The highly active Pd sites in the new coordination environment under H2 are eliminated by oxidation, which, when performed at a high temperature, also redisperses Pdn and facilitates the reduction of TiO2. In contrast, Pd1 sinters into crystalline, ∼5 nm particles (PdNP) during CO treatment, deactivating Pd1/TiO2. During the rWGS reaction, the two Pd evolution pathways coexist. The activation by H2 dominates, leading to the increasing rate with time-on-stream, and steady-state Pd active sites similar to the ones formed under H2. This work demonstrates how the coordination environment and nuclearity of metal sites on a SAC evolve during catalysis and pretreatments and how their activity is modulated by these behaviors. These insights on SAC dynamics and the structure-function relationship are valuable to mechanistic understanding and catalyst design.

Aqueous Structure of Lanthanide-EDTA Coordination Complexes Determined by a Combined DFT/EXAFS Approach.

Sustainable production of rare earth elements (REEs) is critical for technologies needed for climate change mitigation, including wind turbines and electric vehicles. However, separation technologies currently used in REE production have large environmental footprints, necessitating more sustainable strategies. Aqueous, affinity-based separations are examples of such strategies. To make these technologies feasible, it is imperative to connect aqueous ligand structure to ligand selectivity for individual REEs. As a step toward this goal, we analyzed the extended X-ray absorption fine structure (EXAFS) of four lanthanides (La, Ce, Pr, and Nd) complexed by a common REE chelator, ethylenediaminetetraacetic acid (EDTA) to determine the aqueous-phase structure. Reference structures from density functional theory (DFT) were used to help fit the EXAFS spectra. We found that all four Ln-EDTA coordination complexes formed 9-coordinate structures with 6 coordinating atoms from EDTA (4 carboxyl oxygen atoms and 2 nitrogen atoms) and 3 oxygen atoms from water molecules. All EXAFS fits were of high quality (R-factor < 0.02) and showed decreasing average first-shell coordination distance across the series (2.62-2.57 Å from La-Nd), in agreement with DFT (2.65-2.56 Å from La-Nd). The insights determined herein will be useful in the development of ligands for sustainable rare earth elements (REE) separation technologies.

Differences in clinical outcomes according to the time interval between the bridge to surgery stenting and surgery for left-sided malignant colorectal obstruction.

BACKGROUND: Self-expandable metal stent (SEMS) placement is commonly used as a bridge to surgery (BTS) for left-sided malignant colorectal obstruction (MCO). However, the optimal time interval between BTS stenting and surgery for left-sided MCO is unclear, and the results of previous studies are conflicting. This study aimed to determine the differences in clinical outcomes according to the time interval between BTS stenting and surgery in left-sided MCO. METHODS: Data from 594 patients who underwent SEMS placement for MCO between January 2009 and December 2018 were reviewed. Among them, 148 patients who underwent SEMS placement as BTS treatment and curative surgery were enrolled. The enrolled patients were divided into three groups according to the interval between BTS stenting and surgery: group 1 (interval ≤2 weeks), group 2 (interval 2-3 weeks), and group 3 (interval >3 weeks). RESULTS: Group 2 and 3 patients underwent significantly higher rates of laparoscopic surgery than those in group 1 (83.7, 81.0 vs. 53.2 %, respectively; P=0.003, P=0.003, respectively). Also, rates of stoma formation directly after resection were significantly higher in group 1 compared to groups 2 and 3 (21.3 vs 2.3, 6.9%, respectively; P=0.008, P=0.043, respectively). Bridging interval had no effect on SEMS-related complications, resection-related complications, 90-day mortality, permanent stoma formation, 3-year disease-free survival, and 3-year overall survival. CONCLUSIONS: A bridging interval of > 2 weeks between BTS stenting and surgery for left-sided MCO is preferable for lower stoma formation rates and higher rates of laparoscopic approach operation, with no difference in short-term and long-term outcomes including complication, mortality, and survival.

Beyond Radical Rebound: Methane Oxidation to Methanol Catalyzed by Iron Species in Metal-Organic Framework Nodes.

Recent work has exploited the ability of metal-organic frameworks (MOFs) to isolate Fe sites that mimic the structures of sites in enzymes that catalyze selective oxidations at low temperatures, opening new pathways for the valorization of underutilized feedstocks such as methane. Questions remain as to whether the radical-rebound mechanism commonly invoked in enzymatic and homogeneous systems also applies in these rigid-framework materials, in which resisting the overoxidation of desired products is a major challenge. We demonstrate that MOFs bearing Fe(II) sites within Fe3-µ3-oxo nodes active for conversion of CH4 + N2O mixtures (368-408 K) require steps beyond the radical-rebound mechanism to protect the desired CH3OH product. Infrared spectra and density functional theory show that CH3OH(g) is stabilized as Fe(III)-OCH3 groups on the MOF via hydrogen atom transfer with Fe(III)-OH groups, eliminating water. Consequently, upon addition of a protonic zeolite in inter- and intrapellet mixtures with the MOF, we observed increases in CH3OH selectivity with increasing ratio and proximity of zeolitic H+ to MOF-based Fe(II) sites, as methanol is protected within the zeolite. We infer from the data that CH3OH(g) is formed via the radical-rebound mechanism on Fe(II) sites but that subsequent transport and dehydration steps are required to protect CH3OH(g) from overoxidation. The results demonstrate that the radical-rebound mechanism commonly invoked in this chemistry is insufficient to explain the reactivity of these systems, that the selectivity-controlling steps involve both chemical and physical rate phenomena, as well as offering a strategy to mitigate overoxidation in these and similar systems.

A Theory-Guided X-ray Absorption Spectroscopy Approach for Identifying Active Sites in Atomically Dispersed Transition-Metal Catalysts.

Atomically dispersed supported metal catalysts offer new properties and the benefits of maximized metal accessibility and utilization. The characterization of these materials, however, remains challenging. Using atomically dispersed platinum supported on crystalline MgO (chosen for its well-defined bonding sites) as a prototypical example, we demonstrate how systematic density functional theory calculations for assessing all the potentially stable platinum sites, combined with automated analysis of extended X-ray absorption fine structure (EXAFS) spectra, leads to unbiased identification of isolated, surface-enveloped platinum cations as the catalytic species for CO oxidation. The catalyst has been characterized by atomic-resolution imaging and EXAFS and high-energy resolution fluorescence detection X-ray absorption near edge spectroscopy. The proposed platinum sites are in agreement with experiment. This theory-guided workflow leads to rigorously determined structural models and provides a more detailed picture of the structure of the catalytically active site than what is currently possible with conventional EXAFS analyses. As this approach is efficient and agnostic to the metal, support, and catalytic reaction, we posit that it will be of broad interest to the materials characterization and catalysis communities.

Excited-State Bond Contraction and Charge Migration in a Platinum Dimer Complex Characterized by X-ray and Optical Transient Absorption Spectroscopy.

Interactions between metal centers in dimeric transition metal complexes (TMCs) play important roles in their excited-state energetics and pathways and, thus, affect their photophysical properties relevant to their applications, for example, photoluminescent materials and photocatalysis. Here, we report electronic and nuclear structural dynamics studies of two photoexcited pyrazolate-bridged [Pt(ppy)(µ-R2pz)]2-type Pt(II) dimers (ppy = 2-phenylpyridine, µ-R2pz = 3,5-substituted pyrazolate): [Pt(ppy)(µ-H2pz)]2 (1) and [Pt(NDI-ppy)(µ-Ph2pz)]2 (2, NDI = 1,4,5,8-naphthalenediimide), both of which have distinct ground-state Pt-Pt distances. X-ray transient absorption (XTA) spectroscopy at the Pt LIII-edge revealed a new d-orbital vacancy due to the one-electron oxidation of the Pt centers in 1 and 2. However, while a transient Pt-Pt contraction was observed in 2, such an effect was completely absent in 1, demonstrating how the excited states of these complexes are determined by the overlap of the Pt (dz2) orbitals, which is tuned by the steric bulk of the pyrazolate R-groups in the 3- and 5-positions. In tandem with analysis of the Pt-Pt distance structural parameter, we observed photoinduced electron transfer in 2 featuring a covalently linked NDI acceptor on the ppy ligand. The formation and subsequent decay of the NDI radical anion absorption signals were detected upon photoexcitation using optical transient absorption spectroscopy. The NDI radical anion decayed on the same time scale, hundreds of picoseconds, as that of the d-orbital vacancy signal of the oxidized Pt-Pt core observed in the XTA measurements. The data indicated an ultrafast formation of the charge-separated state and subsequent charge recombination to the original Pt(II-II) species.

Comparison of abdominal and minimally invasive radical hysterectomy in patients with early stage cervical cancer.

PURPOSE: The aim of this study was to compare survival outcomes of open radical hysterectomy and minimally invasive radical hysterectomy (MIS) in early stage cervical cancer. METHODS: A retrospective analysis of 148 patients with stage IB1 - IIA2 cervical cancer who underwent either minimally invasive or open radical hysterectomy. Tumor characteristics, recurrence rate, disease-free survival (DFS), and overall survival (OS) were compared according to surgical approach. RESULTS: In total, 110 and 38 patients were assigned to open surgery and MIS groups. After a medical follow-up of 42.1 months, the groups showed similar survival outcomes (recurrence rate, DFS, and OS). However, in patients with tumor size >2 cm, recurrence rate was significantly higher in MIS group (22.5% vs 0%; p=0.008). And in patients with tumor size >2 cm, MIS group showed significantly poorer DFS than open surgery group (p=0.017), although OS was similar between the two groups (p=0.252). CONCLUSION: In patients with tumor size >2 cm, MIS was associated with higher recurrence rates and poorer DFS than open surgery. However, in patients with tumor size ≤2 cm, MIS did not seem to compromise oncologic outcomes.

Clinical outcomes of endoscopic resection for colorectal laterally spreading tumors with advanced histology.

BACKGROUND: Colorectal laterally spreading tumors (LSTs) are large, flat neoplasms that are usually treated using different endoscopic techniques based on their morphology, size, and histology. The aim of this study was to evaluate the clinical outcomes of LSTs with advanced histology treated by endoscopic resection. METHODS: A total of 246 LSTs with advanced histology [i.e., high-grade dysplasia (HGD) and adenocarcinoma (AC)] treated by endoscopic resection [i.e., endoscopic mucosal resection (EMR), EMR-precutting (EMR-P), and endoscopic submucosal dissection (ESD)] were enrolled. Clinicopathological characteristics were collected by review of patient's medical records. RESULTS: The en bloc resection and R0 resection rates were 75.6% and 85.0%, respectively. The bleeding and perforation rates were 10.2% and 2.4%, respectively. The frequency of cancerous pit pattern and bleeding was significantly higher in LSTs with AC than in LSTs with HGD. The R0 resection rate in LSTs with HGD was significantly higher than that in LSTs with AC. The frequency of cancerous pit patterns in LST cases with submucosal AC was significantly higher than those with intramucosal AC. The mean size of the LSTs was significantly larger in ESD group than in EMR or EMR-P groups. The frequencies of nodular mixed subtype, cancerous pit patterns, and en bloc resection rates were significantly higher in the ESD group than in the EMR or EMR-P groups. However, the frequency of perforation was significantly higher in EMR-P group than in EMR or ESD groups. CONCLUSIONS: These results indicate that ESD is a more acceptable treatment approach for resection of colorectal LSTs of larger size, with nodular mixed subtype, having a cancerous pit pattern or AC, using either en bloc or curative resection methods, compared to EMR or EMR-P procedures.

Insulin hexamer dissociation dynamics revealed by photoinduced T-jumps and time-resolved X-ray solution scattering.

The structural dynamics of insulin hexamer dissociation were studied by the photoinduced temperature jump technique and monitored by time-resolved X-ray scattering. The process of hexamer dissociation was found to involve several transient intermediates, including an expanded hexamer and an unstable tetramer. Our findings provide insights into the mechanisms of protien-protein association.

Solution Structures of Highly Active Molecular Ir Water-Oxidation Catalysts from Density Functional Theory Combined with High-Energy X-ray Scattering and EXAFS Spectroscopy.

The solution structures of highly active Ir water-oxidation catalysts are elucidated by combining density functional theory, high-energy X-ray scattering (HEXS), and extended X-ray absorption fine structure (EXAFS) spectroscopy. We find that the catalysts are Ir dimers with mono-µ-O cores and terminal anionic ligands, generated in situ through partial oxidation of a common catalyst precursor. The proposed structures are supported by (1)H and (17)O NMR, EPR, resonance Raman and UV-vis spectra, electrophoresis, etc. Our findings are particularly valuable to understand the mechanism of water oxidation by highly reactive Ir catalysts. Importantly, our DFT-EXAFS-HEXS methodology provides a new in situ technique for characterization of active species in catalytic systems.

Prognostic significance of the concomitant existence of lymphovascular and perineural invasion in locally advanced gastric cancer patients who underwent curative gastrectomy and adjuvant chemotherapy.

OBJECTIVE: In this study, we evaluated the prognostic significance of the concomitant existence of lymphovascular invasion and perineural invasion in patients with advanced gastric cancer. METHODS: A total of 206 consecutive patients with Stage II or III gastric cancer who underwent curative D2 gastrectomy and adjuvant chemotherapy from April 2004 to December 2011 were analyzed. Patients were classified into four groups according to the presence (+) or absence (-) of lymphovascular invasion and perineural invasion: lymphovascular invasion-/perineural invasion- (n = 33), lymphovascular invasion+/perineural invasion- (n = 31), lymphovascular invasion-/perineural invasion+ (n = 54) and lymphovascular invasion+/perineural invasion+ (n = 88). RESULTS: A total of 136 patients (66.0%) received 5-fluorouracil plus cisplatin adjuvant chemotherapy and 70 patients (34.0%) received TS-1. During the median follow-up period of 35.18 months, the median disease-free survival times for lymphovascular invasion-/perineural invasion-, lymphovascular invasion+/perineural invasion- and lymphovascular invasion-/perineural invasion+ were not reached at the time of analysis; however, median disease-free survival for lymphovascular invasion+/perineural invasion+ was the worst (36.73 months, P = 0.001). The median overall survival in the four groups was also not reached at the time of analysis; however, median overall survival with lymphovascular invasion+/perineural invasion+ was the poorest (P = 0.002). In a multivariate analysis, lymphovascular invasion+/perineural invasion+ was an independent prognostic factor for both disease-free survival (hazard ratio = 1.940, 95% confidence interval 1.157-3.252, P = 0.012) and overall survival (hazard ratio = 2.973, 95% confidence interval 1.561-5.662, P = 0.001). CONCLUSIONS: The concomitant existence of lymphovascular and perineural invasion has a significant prognostic impact on disease-free survival and overall survival in patients with Stage II or III gastric cancer.

The effects of side-chain-induced disorder on the emission spectra and quantum yields of oligothiophene nanoaggregates: a combined experimental and MD-TDDFT study.

Oligomeric thiophenes are commonly used components in organic electronics and solar cells. These molecules stack and/or aggregate readily under the processing conditions used to form thin films for these applications, significantly altering their optical and charge-transport properties. To determine how these effects depend on the substitution pattern of the thiophene main chains, nanoaggregates of three sexithiophene oligomers having different alkyl substitution patterns were formed using solvent-poisoning techniques and studied using steady-state and time-resolved emission spectroscopy. The results indicate the substantial role played by the side-chain substituents in determining the emissive properties of these species. Both the measured spectral changes and their dependence on substitution are well-modeled by combined quantum chemistry and molecular dynamics simulations. The simulations connect the side-chain-induced disorder, which determines the favorable chain-packing configurations within the aggregates, with their measured electronic spectra.

Immunological subtyping of salivary gland cancer identifies histological origin-specific tumor immune microenvironment.

Gene expression analysis enhances proper cancer subtyping, a better understanding of the molecular characteristics of cancer, and strategies for precision medicine. However, salivary gland cancer (SGC) subtyping remains largely unexplored because of its rarity and diverse histopathological and immunological characteristics. This study aimed to determine whether the histological origin and immunological characteristics of SGC subtypes are intrinsic tumor immunity factors. We performed immune profiling of 94 RNA-seq of SGC tissues and found that the SGCs that originated from the excretory duct (ED), such as the salivary duct and mucoepidermoid carcinomas, exhibit higher immunity than those from the intercalated duct (ID), such as the adenoid cystic and myoepithelial carcinomas, based on the computationally predicted immune score (p < 0.001), immune cell enrichment in the tumor immune microenvironment (TIME) (p < 0.001), T-cell receptor diversity (p < 0.001), and expression of signal I (major histocompatibility complex, MHC, p < 0.001) and signal II (co-stimulatory, p < 0.001 and co-inhibitory, p < 0.001) genes. Further analysis revealed that tolerogenic dendritic cell-induced dysfunctional T-cell populations and T-cell exclusion in the TIME are the major immune evasive mechanisms of the ED-and ID-derived SGCs, respectively.

Impact of Local Structure in Supported CaO Catalysts for Soft-Oxidant-Assisted Methane Coupling Assessed through Ca K-Edge X-ray Absorption Spectroscopy.

Soft-oxidant-assisted methane coupling has emerged as a promising pathway to upgrade methane from natural gas sources to high-value commodity chemicals, such as ethylene, at selectivities higher than those associated with oxidative (O2) methane coupling (OCM). To date, few studies have reported investigations into the electronic structure and the microscopic physical structure of catalytic active sites present in the binary metal oxide catalyst systems that are known to be effective for this reaction. Correlating the catalyst activity to specific active site structures and electronic properties is an essential aspect of catalyst design. Here, we used X-ray absorption spectroscopy at the Ca K-edge to ascertain the most probable local environment of Ca in the ZnO-supported Ca oxide catalysts. These catalysts are shown here to be active for N2O-assisted methane coupling (N2O-OCM) and have previously been reported to be active for CO2-assisted methane coupling (CO2-OCM). X-ray absorption near edge structure features at multiple Ca loadings are interpreted through simulated spectra derived from ab initio full multiple scattering calculations. These simulations included consideration of CaO structures organized in multiple spatial arrangements-linear, planar, and cubic-with separate analyses of Ca atoms in the surfaces and bulk of the three-dimensional structures. The morphology of the oxide clusters was found to influence the various regions of the X-ray absorption spectrum differently. Experiment and theory show that for low-Ca-loading catalysts (≤1 mol %), which contain sites particularly active for methane coupling, Ca primarily exists in an oxidized state that is consistent with the coordination environment of Ca ions in one- and two-dimensional clusters. In addition to their unique nanoscale structures, the spectra also indicate that these clusters have varying degrees of undercoordinated surface Ca atoms that could further influence their catalytic activities. The local Ca structure was correlated to methane coupling activity from N2O-OCM and previously reported CO2-OCM reactor studies. This study provides a unique perspective on the relationship between the catalyst physical and electronic structure and active sites for soft-oxidant-assisted methane coupling, which can be used to inform future catalyst development.

Impact of Prospero Homeobox-1 (PROX-1) οn the Oncogenic Phenotypes of Hepatocellular Carcinoma Cells.

BACKGROUND/AIM: Transcriptional factor prospero homeobox-1 (PROX-1) is crucial for the embryonic development of various organs and cell fate specification. It exhibits either an oncogenic or tumor suppressive activity depending on cancer types. However, the relationship between PROX-1 and hepatocellular carcinoma (HCC) remains obscure. This study was conducted to investigate the effect of PROX-1 on the invasive and oncogenic phenotypes of human HCC cells. MATERIALS AND METHODS: The effect of PROX-1 on tumor cell behavior was investigated by using a pcDNA-myc vector and a small interfering RNA in HepG2 and Huh7 human HCC cell lines. Flow cytometry, migration, invasion, proliferation, and tube formation assays were performed. PROX-1 expression in human HCC cells was explored by western blotting. RESULTS: PROX-1 overexpression enhanced tumor cell proliferation and inhibited apoptosis and cell cycle arrest by modulating the activities of caspase-3, PARP, and cyclin-dependent kinase inhibitors, including p21, p27, and p57 in HCC cells. After PROX-1 overexpression, the number of migrating and invading HCC cells significantly increased, and the expression levels of N-cadherin and Snail increased in HCC cells. PROX-1 overexpression enhanced angiogenesis through increased VEGF-A and VEGF-C expression and decreased angiostatin expression. PROX-1 overexpression also increased the phosphorylation of glycogen synthase kinase-3ß (GSK-3ß) and forkhead box O1 (FOXO1) in HCC cells. After PROX-1 knockdown, their phosphorylation was reversed. CONCLUSION: PROX-1 overexpression is associated with the invasive and oncogenic phenotypes of human HCC cells via GSK-3ß and FOXO1 phosphorylation.