Correlative In Situ Spectro-Microscopy of Supported Single CuO Nanoparticles: Unveiling the Relationships between Morphology and Chemical State during Thermal Reduction.

The activity, selectivity, and lifetime of nanocatalysts critically depend on parameters such as their morphology, support, chemical composition, and oxidation state. Thus, correlating these parameters with their final catalytic properties is essential. However, heterogeneity across nanoparticles (NPs) is generally expected. Moreover, their nature can also change during catalytic reactions. Therefore, investigating these catalysts in situ at the single-particle level provides insights into how these tunable parameters affect their efficiency. To unravel this question, we applied spectro-microscopy to investigate the thermal reduction of SiO2-supported copper oxide NPs in ultrahigh vacuum. Copper was selected since its oxidation state and morphological transformations strongly impact the product selectivity of many catalytic reactions. Here, the evolution of the NPs' chemical state was monitored in situ during annealing and correlated with their morphology in situ. A reaction front was observed during the reduction of CuO to Cu2O. From the temperature dependence of this front, the activation energy was extracted. Two parameters were found to strongly influence the NP reduction: the initial nanoparticle size and the chemical state of the SiO2. substrate. The CuOx reduction was found to be completed first on smaller NPs and was also favored over partially reduced SiOx regions that resulted from X-ray beam irradiation. This methodology with single-particle level spectro-microscopy resolution provides a way of isolating the influence of diverse morphologic, electronic, and chemical influences on a chemical reaction. The knowledge gained is crucial for the future design of more complex multimetallic catalytic systems.

Surface charge dynamics on air-exposed ferroelectric Pb(Zr,Ti)O3(001) thin films.

Probing of the free surface ferroelectric properties of thin polar films can be achieved either by estimating the band bending variance under the top-most layer or by studying the extent of the extrinsic charge accumulated outside the surface. Photoemitted or incoming low-energy electrons can be used to characterize locally both properties in a spectromicroscopic approach. Thin ferroelectric lead zirco-titanate (PZT) is investigated by combining low energy/mirror electron microscopy (LEEM/MEM) with photoemission electron microscopy (PEEM) and high-resolution photoelectron spectroscopy (XPS). Significant extrinsic negative compensation charge is proven to accumulate on the surface of the outward polarized thin film, indicated by high MEM-LEEM transition values, up to 15.3 eV, and is correlated with the surface electrostatic potential, which can be partially screened either by electrons interacting with the sample or by soft X-rays through the ejection of secondary electrons and generation of positive charge under the surface. A radiation-induced surface charge compensation effect is observed. The study indicates that air-exposed high quality ferroelectric thin films show large negative surface potentials, determined locally on the surface, which are nevertheless sensitive to beam damage and molecular desorption. These values represent a confirmation of previously estimated surface potential energy values determined from the LEED data on clean surfaces.

Preparation and stability of the hexagonal phase of samarium oxide on Ru(0001).

We have used low-energy electron microscopy (LEEM), micro-illumination low-energy electron diffraction (µLEED) supported by ab initio calculations, and X-ray absorption spectroscopy (XAS) to investigate in-situ and in real-time the structural properties of Sm2O3 deposits grown on Ru(0001), a rare-earth metal oxide model catalyst. Our results show that samarium oxide grows in a hexagonal A-Sm2O3 phase on Ru(0001), exhibiting a (0001) oriented-top facet and (113) side facets. Upon annealing, a structural transition from the hexagonal to cubic phase occurs, in which the Sm cations exhibit the +3 oxidation state. The unexpected initial growth in the A-Sm2O3 hexagonal phase and its gradual transition to a mixture with cubic C-Sm2O3 showcases the complexity of the system and the critical role of the substrate in the stabilization of the hexagonal phase, which was previously reported only at high pressures and temperatures for bulk samaria. Besides, these results highlight the potential interactions that Sm could have with other catalytic compounds with respect to the here gathered insights on the preparation conditions and the specific compounds with which it interacts.

Pattern Formation in Catalytic H2 Oxidation on Rh: Zooming in by Correlative Microscopy.

Spatio-temporal nonuniformities in H2 oxidation on individual Rh(h k l) domains of a polycrystalline Rh foil were studied in the 10-6 mbar pressure range by photoemission electron microscopy (PEEM), X-ray photoemission electron microscopy (XPEEM), and low-energy electron microscopy (LEEM). The latter two were used for in situ correlative microscopy to zoom in with significantly higher lateral resolution, allowing detection of an unusual island-mediated oxygen front propagation during kinetic transitions. The origin of the island-mediated front propagation was rationalized by model calculations based on a hybrid approach of microkinetic modeling and Monte Carlo simulations.

In Situ Analysis of the Facets of Cu-Based Electrocatalysts in Alkaline Media Using Pb Underpotential Deposition.

Establishing relationships between the surface atomic structure and activity of Cu-based electrocatalysts for CO2 and CO reduction is hindered by probable surface restructuring under working conditions. Insights into these structural evolutions are scarce as techniques for monitoring the surface facets in conventional experimental designs are lacking. To directly correlate surface reconstructions to changes in selectivity or activity, the development of surface-sensitive, electrochemical probes is highly desirable. Here, we report the underpotential deposition of lead over three low index Cu single crystals in alkaline media, the preferred electrolyte for CO reduction studies. We find that underpotential deposition of Pb onto these facets occurs at distinct potentials, and we use these benchmarks to probe the predominant facet of polycrystalline Cu electrodes in situ. Finally, we demonstrate that Cu and Pb form an irreversible surface alloy during underpotential deposition, which limits this method to investigating the surface atomic structure after reaction.

Neuroprotective Effect of α-Mangostin in the Ameliorating Propionic Acid-Induced Experimental Model of Autism in Wistar Rats.

Several studies have documented the role of hyper-activation of extracellular signal-regulated kinases (ERK) in Autism pathogenesis. Alpha-mangostin (AMG) is a phytoconstituents with anti-oxidants, anti-inflammatory, and ERK inhibition properties in many diseases. Our research aims to investigate the neuroprotective effect of AMG in the rat model of intracerebroventricular-propionic acid (ICV-PPA) induced autism with a confirmation of its effect on the ERK signaling. Autism was induced in Wistar rats (total 36 rats; 18 male/18 female) by multiple doses of PPA through ICV injection for 11 days. Actophotometer and beam walking tasks were used to evaluate animals' motor abilities, and the Morris water maze task was utilized to confirm the cognition and memory in animals. Long term administration of AMG 100 mg/kg and AMG 200mg/kg continued from day 12 to day 44 of the experiment. Before that, animals were sacrificed, brains isolated, morphological, gross pathological studies were performed, and neurochemical analysis was performed in the brain homogenates. Cellular and molecular markers, including ERK, myelin basic protein, apoptotic markers including caspase-3, Bax, Bcl-2, neuroinflammatory markers, neurotransmitters, and oxidative stress markers, have been tested throughout the brain. Thus, AMG reduces the overactivation of the ERK signaling and also restored autism-like behavioral and neurochemical alterations.

Exploring Molecular Approaches in Amyotrophic Lateral Sclerosis: Drug Targets from Clinical and Pre-Clinical Findings.

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease (MND) characterized by the death of upper and lower motor neurons (corticospinal tract) in the motor cortex, basal ganglia, brain stem, and spinal cord. The patient experiences the sign and symptoms between 55 to 75 years of age, which include impaired motor movement, difficulty in speaking and swallowing, grip loss, muscle atrophy, spasticity, and sometimes associated with memory and cognitive impairments. Median survival is 3 to 5 years after diagnosis and 5 to 10% of the patients live for more than 10 years. The limited intervention of pharmacologically active compounds, that are used clinically, is majorly associated with the narrow therapeutic index. Pre-clinically established experimental models, where neurotoxin methyl mercury mimics the ALS like behavioural and neurochemical alterations in rodents associated with neuronal mitochondrial dysfunctions and downregulation of adenyl cyclase mediated cAMP/CREB, is the main pathological hallmark for the progression of ALS in central as well in the peripheral nervous system. Despite the considerable investigation into neuroprotection, it still constrains treatment choices to strong care and organization of ALS complications. Therefore, this current review specially targeted the investigation of clinical and pre-clinical features available for ALS to understand the pathogenic mechanisms and to explore the pharmacological interventions associated with the up-regulation of intracellular adenyl cyclase/cAMP/ CREB and activation of mitochondrial-ETC coenzyme-Q10 as a future drug target in the amelioration of ALS mediated motor neuronal dysfunctions.

Elucidation of Abnormal Extracellular Regulated Kinase (ERK) Signaling and Associations with Syndromic and Non-syndromic Autism.

Autism is a highly inherited and extremely complex disorder in which results from various cases indicate chromosome anomalies, unusual single-gene mutations, and multiplicative effects of particular gene variants, characterized primarily by impaired speech and social interaction and restricted behavior. The precise etiology of Autism Spectrum Disorder (ASD) is currently unclear. The extracellular signal-regulated kinase (ERK) signaling mechanism affects neurogenesis and neuronal plasticity during the development of the central nervous mechanism. In this regard, the pathway of ERK has recently gained significant interest in the pathogenesis of ASD. The mutation occurs in a few ERK components. Besides, the ERK pathway dysfunction lies in the upstream of modified translation and contributes to synapse pathology in syndromic types of autism. In this review, we highlight the ERK pathway as a target for neurodevelopmental disorder autism. In addition, we summarize the regulation of the ERK pathway with ERK inhibitors in neurological disorders. In conclusion, a better understanding of the ERK signaling pathway provides a range of therapeutic options for autism spectrum disorder.

Fingerprint Voltammograms of Copper Single Crystals under Alkaline Conditions: A Fundamental Mechanistic Analysis.

A critical step toward the systematic development of electrocatalysts is the determination of the microscopic structure and processes at the electrified solid/electrolyte interface. The major challenges toward this end for experiment and computations are achieving sufficient cleanliness and modeling the complexity of electrochemical systems, respectively. In this sense, benchmarks of well-defined model systems are sparse. This work presents a rigorous joint experimental-theoretical study on the single-crystal (SC) Cu/aqueous interface. Within typical computational uncertainties, we find quantitative agreement between simulated and experimentally measured voltammograms, which allows us to unequivocally identify the *OH adsorption feature in the fingerprint region of Cu(110), Cu(100), and Cu(111) SCs under alkaline conditions. We find the inclusion of hydrogen evolution reaction kinetics in the theoretical model to be crucial for an accurate steady-state description that gives rise to a negligible H* coverage. A purely thermodynamic description of the H* coverage through a Pourbaix analysis would incorrectly lead to a H* adsorption peak. The presented results establish a fundamental benchmark for all electrochemical applications of Cu.

Adenylate cyclase activator forskolin alleviates intracerebroventricular propionic acid-induced mitochondrial dysfunction of autistic rats.

Neuronal mitochondrial dysfunction increases inflammatory mediators and leads to free radical generation and anti-oxidant enzymatic alterations, which are major neuropathological hallmarks responsible for autism. Mitochondrial dysfunction in autism is associated with decreased ATP levels due to reduced levels of cyclic adenosine monophosphate. Rat models of autism were established by intracerebroventricular injection of propionic acid. These rat models had memory dysfunction, decreased muscle coordination and gait imbalance. Biochemical estimation of propionic acid-treated rats showed changes in enzyme activity in neuronal mitochondrial electron transport chain complexes and increases in pro-inflammatory cytokines, oxidative stress and lipid biomarkers. Oral administration of 10, 20 and 30 mg/kg adenylate cyclase activator forskolin for 15 days reversed these changes in a dose-dependent manner. These findings suggest that forskolin can alleviate neuronal mitochondrial dysfunction and improve neurological symptoms of rats with autism. This study was approved by the RITS/IAEC, SIRSA, HARYANA on March 3, 2014 (approval No. RITS/IAEC/2014/03/03).

On the Possibilities and Considerations of Interfacing Ultra-High Vacuum Equipment with an Electrochemical Setup.

Efficient electrocatalysts are required in order for electrocatalysis to play a large role in a future largely based on renewable energy sources. To rationally design these catalysts we need to understand the fundamental origin of their activities. In order to elucidate the relationship between catalyst structure and electrochemical behaviour, we investigate well-defined single-crystal catalysts in a UHV chamber interfaced with an electrochemical setup. Using the capabilities of UHV based methods, we can prepare more complex surface structures than it is possible with traditional EC methods and investigate their electrochemical behaviour. We exemplify this by showing results from both clean and intentionally structured Pt(111), Cu(111) and Pt/Cu(111).

Non-Noble Cobalt Tungstate Catalyst for Effective Electrocatalytic Oxidation of Borohydride.

Morphologically tuned cobalt tungstate (CoWO4), a new entrant toward borohydride oxidation reaction (BOR), was explored as it exhibited negligible H2 evolution while enabling rapid BOR. A simple synthetic strategy was employed and fine-tuned to obtain different morphologies of CoWO4 whose urchin-shaped variant gave exciting activity toward BOR. An early and quite negative onset potential of -1.14 V was observed giving a maximum obtainable specific current density of 105.3 mA mg-1. The synthesized variants were investigated in depth by various electrochemical measurements and assessed in light of previous reports toward BOR activity. Hydrodynamic studies were also performed to ascertain the nature of these static electrochemical measurements. Quantitative assessment of the evolved H2, a prominent competitive reaction to BOR, was performed suggesting minimal interference. The probable origin of such morphology-dependent activity was subsequently studied in detail by high-resolution transmission electron microscopy (HR-TEM) analysis, revealing nanometric structures in the urchin-like variant, which enhance the obtainable BOR activity.

Stabilization of Cobalt-Polyoxometalate over Poly(ionic liquid) Composites for Efficient Electrocatalytic Water Oxidation.

The key to unlock a renewable, clean, and energy-dense hydrogen fuel lies in designing an efficient oxygen evolving catalyst exhibiting high activity, stability, and cost-effectiveness. This report addresses an improved activity toward oxygen evolution by a composite of cobalt-polyoxometalate [Co4(H2O)2(PW9O34)2]10- (CoPOM) and an ionic polymer, poly(vinyl butyl imidazolium) (PVIM), in highly alkaline media. PVIM provides a stable platform for CoPOM and acts as a conductive linker between CoPOM and the electrode surface, forming a concrete solid composite, which balances the multinegative charge of CoPOM synergistically. This improved stability and conductivity of CoPOM by PVIM in the PVIM-CoPOM composite performs remarkable electrocatalytic water oxidation with a very low overpotential of 0.20 V and a very high current density of 250 mA/cm2 (at 1.75 V vs RHE) with a turnover frequency (TOF) of 52.8 s-1 in 1 M NaOH.

Ether and siloxane functionalized ionic liquids and their mixtures as electrolyte for lithium-ion batteries.

The present study deals with an investigation of two novel imidazolium ionic liquids bearing ether-ether (1O2O2-Im-2O1) or ether-siloxane (1O2O2-Im-1SiOSi) functionalities with TFSI anion and their mixtures with propylene carbonate as electrolytes in lithium-ion batteries. The electrochemical stability and conductivity of these novel ILs were analyzed by electrochemical studies, such as cyclic voltammetry, linear sweep voltammetry and impedance measurements. The applicability of these ILs as electrolytes in Li-ion batteries was studied in the presence of a high concentration of LiTFSI (1 mol kg(-1) electrolyte) and the ether-ether IL was shown to possess a high electrochemical stability window (ESW) of 5.9 V and good conductivity of 2.2 mS cm(-1). The electrochemical stability and conductivity were further complimented by self-diffusion of different ions using pulsed gradient spin-echo (PGSE) NMR, viscosity and thermal properties like TGA and DSC analysis. More importantly, we explored the effect of temperature on the electrochemical stability and conductivity of these ILs by electrochemical impedance spectroscopy.

Electrocatalytic Activity of Tungsten Oxide Nanoclusters Grafted on Mesoporous Nitrogen-Rich Carbon Material in the Dioxygen Reduction Reaction.

Nanosized clusters of tungsten oxide grafted onto a mesoporous nitrogen-rich carbon material (WOx/MNCx) have been synthesized and explored for their remarkable ability towards dioxygen reduction. The composite catalyst exhibits a lower overpotential and significant stability, which paves the way towards improvement of the nonprecious yet proficient electrocatalyst for the oxygen reduction reaction (ORR) occurring at the cathode in alkaline medium. The electrocatalytic activity of the synthesized catalyst towards the ORR have been examined by electrochemical techniques, such as cyclic voltammetry, rotating disk electrode and rotating ring disk electrode measurements, along with electrochemical quartz crystal microbalance studies in alkaline medium. The WOx/MNCx catalyst shows better electrocatalytic activity towards the ORR in alkaline medium and could be used for successful application in low-temperature fuel cells.