1.1 W diode-pumped Er:Yb laser at 1520 nm

Laser oscillation at a wavelength of 1520 nm was obtained in an Er:Yb:YAl(3)(BO(3))(4) crystal end pumped by a 970 nm diode laser. Under the absorbed pump power of 14.6 W, quasi-continuous-wave output powers of 1.1 W with slope efficiency of 13% and 0.8 W with slope efficiency of 11% were achieved in hemispherical and plano-plano cavities, respectively. The laser spectra were recorded for both cavities. The influence of the thermal load in the crystal on the 1520 nm laser oscillation was analyzed.     

Polarized spectroscopic properties of Nd-doped KGd(WO4)2 single crystal

The polarized absorption spectra, infrared fluorescence spectra, upconversion visible fluorescence spectra, and fluorescence decay curve of orientated Nd³⁺:KGd(WO₄)₂ crystal were measured at room-temperature. Some important spectroscopic parameters were investigated in detail in the framework of the Judd-Ofelt theory and the Fuchtbauer-Ladenburg formula. The effect of the crystal structure on the spectroscopic properties of the Nd³⁺ ions was analyzed. The relation among the spectroscopic parameters and the laser performances of the Nd³⁺:KGd(WO₄)₂ crystal was discussed.     

Effect of post-deposition annealing temperature on RF-sputtered HfO2 thin film for advanced CMOS technology

Structural and electrical properties of HfO₂ gate-dielectric metal-oxide-semiconductor (MOS) capacitors deposited by sputtering are investigated. The HfO₂ high-k thin films have been deposited on p-type <100> silicon wafer using RF-Magnetron sputtering technique. The Ellipsometric, FTIR and AFM characterizations have been done. The thickness of the as deposited film is measured to be 35.38 nm. Post deposition annealing in N₂ ambient is carried out at 350, 550, 750 °C. The chemical bonding and surface morphology of the film is verified using FTIR and AFM respectively. The structural characterization confirmed that the thin film was free of physical defects and root mean square surface roughness decreased as the annealing temperature increased. The smooth surface HfO₂ thin films were used for Al/HfO₂/p-Si MOS structures fabrication. The fabricated Al/HfO₂/p-Si structure had been used for extracting electrical properties such as dielectric constant, EOT, interface trap density and leakage current density through capacitance voltage and current voltage measurements. The interface state density extracted from the G–V measurement using Hill Coleman method. Sample annealed at 750 °C showed the lowest interface trap density (3.48 × 10¹¹ eV⁻¹ cm⁻²), effective oxide charge (1.33 × 10¹² cm⁻²) and low leakage current density (3.39 × 10⁻⁹ A cm⁻²) at 1.5 V.     

Hydrogen generation from catalytic glucose oxidation by Fe-based electrocatalysts

Iron phosphide films (Fe₂P) grown in situ on stainless steel mesh (SSM) exhibit excellent electrocatalytic performance toward the glucose oxidation reaction (GOR) with robust durability. During GOR, the Fe₂P could be further transformed into the oxidized Fe species with high catalytic activity. The integrated two-electrode glucose electrolytic cell utilizing Fe₂P/SSM and Pt/C exhibited a cell voltage 300 mV lower than water splitting alone, indicating an efficient pathway for H₂ production. These features suggest that the replacement of the sluggish oxygen evolution reaction (OER) with the thermodynamically more favourable GOR in the Pt/C ||Fe₂P/SSM configuration is an attractive alternative for electrolytic H₂ generation.     

Oxygen imaging of living cells and tissues using luminescent molecular probes

Oxygen imaging of biological cells and tissues is becoming increasingly important in cell biology and in the pathophysiology of various hypoxia-related diseases. The optical oxygen-sensing method using luminescent probes provides very useful, high spatial resolution information regarding oxygen distribution in living cells and tissues. This review focuses on recent advances in biological oxygen measurements based on the phosphorescence quenching of probe molecules by oxygen, and on hypoxia-sensitive fluorescent probes. Special attention is devoted to metal complex probes, Pt(II)- and Pd(II)-porphyrins, Ru(II) complexes, and Ir(III) complexes. Current knowledge regarding the mechanism of phosphorescence quenching of metal complexes by oxygen is described in relation to the oxygen sensitivity of the probes, and recent advances in optical oxygen probes and detection techniques for intracellular and tissue oxygen measurements are reviewed, emphasizing the usefulness of chemical modifications for improving probe properties. Tissue oxygen imaging and hypoxic tumor imaging using these metal complex probes demonstrate the vast potential of optical oxygen-sensing methods using luminescent probes.     

Annealing temperature dependent catalytic water oxidation activity of iron oxyhydroxide thin films

Nanostructured iron oxyhydroxide(Fe OOH) thin films have been synthesized using an electrodeposition method on a nickel foam(NF) substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS), field emission scanning electron microscopy(FE-SEM) and linear sweep voltammetry(LSV) to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous Fe OOH thin film is converted into a polycrystalline Fe_2O_3 with hematite crystal structure at a high temperature. The Fe OOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction(OER) in an alkaline 1 M KOH electrolyte. The film annealed at 200 °C shows high catalytic activity with an onset overpotential of 240 m V with a smaller Tafel slope of 48 m V/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 m A/cm~2 and shows good stability in the 1 M KOH electrolyte solution.     

Susceptibility of FeS2 hydrogen evolution performance to sulfide poisoning

The imminent depletion of fossil fuels raises concern over the need for next-generation clean energy. Of numerous alternatives, electrochemical water splitting is a promising method to store energy in the form of hydrogen. In order to benefit from this system, technological advancement in the development of affordable and efficient electrocatalysts for hydrogen evolution reaction is necessary. Transition-metal electrocatalysts composing of earth-abundant elements, specifically natural FeS₂, has demonstrated excellent performance for hydrogen evolution reaction. However, previous studies on platinum surfaces highlighted the detrimental effect toward hydrogen evolution performance upon poisoning of the active sites. In this work, we examine the susceptibility of natural FeS₂ toward sulfide poisoning. Our findings showed that the degradation effect from the introduction of sulfide to natural FeS₂ was not as severe as that observed on platinum. The overpotential (at a current density of 10 mA/cm²) for natural FeS₂ and platinum increased by approximately 20 and 110 mV, respectively.     

Thermodynamic properties of sublimation of the ortho and meta isomers of acetoxy and acetamido benzoic acids

This paper reports vapour pressures measured at several different temperatures using the Knudsen effusion method of ortho-acetoxybenzoic acid (aspirin) (341.1 to 361.1) K, meta-acetoxybenzoic acid (344.2 to 362.2) K, ortho-acetamidobenzoic acid (367.2 to 389.2) K, and meta-acetamidobenzoic acid (423.2 to 441.1) K. The experimental results enabled the determination of the standard molar enthalpies, entropies and Gibbs energies of sublimation, at T = 298.15 K, of the four compounds studied. DSC experiments yield results of the temperature and enthalpy of fusion. The experimental results were compared with literature ones for the para isomers of the acids acetoxybenzoic and acetamidobenzoic. Correlations involving temperature of fusion, and standard molar enthalpy and Gibbs energy of sublimation of several substituted benzoic acids were proposed. Those correlation equations allow a good estimative of volatility of benzoic acid derivatives from their enthalpies of sublimation and temperatures of fusion.     

Influence of loading frequency on the fatigue behaviour of coir fibre reinforced PP composite

The influence of loading frequency on the fatigue behaviour of a coir fibre reinforced polypropylene (PP) composite was studied. The mechanical behaviour was assessed through monotonic tensile and flexural tests, followed by cyclic bending fatigue tests employing a new specimen geometry, with loading frequencies ranging from 5 to 35 Hz. Results revealed that higher strain rates during monotonic loading lead to higher flexural strength, and higher loading frequencies in cyclic tests promote reduction in fatigue life. Fractographic examination showed that one of the reasons for reduced fatigue life under higher loading frequencies might be related to increased heat generation by hysteresis, leading to a fatigue damage mechanism governed by temperature effects. The results, thus, encourage the development of good practices regarding test frequencies in order to be able to uncouple thermal and mechanical effects and provide relevant data for structural integrity assessments.