Influence of dose and ion concentration on formation of binary Al–Ni alloy nanoclusters

Colloidal Al–Ni nanoclusters were prepared in an aqueous polyvinyl alcohol solution containing aluminum chloride and nickel chloride as metal precursors, polyvinyl alcohol as a capping agent, isopropanol as a scavenger of hydroxyl radicals, and distilled water as a solvent. Gamma irradiations were carried out in a ⁶⁰Co gamma source chamber at doses up to 100 kGy. The nanocluster properties were characterized by transmission electron microscopy (TEM), UV–visible spectrophotometry, and X-ray diffraction (XRD). By controlling the dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increase of precursor concentration and decreased with increase of dose. This is owing to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation.     

A Flat-Gain Double-Pass Amplifier with New Hafnia-Bismuth-Erbium Codoped Fiber

An efficient and compact double-pass optical fiber amplifier is demonstrated using a newly developed hafnia bismuth erbium co-doped fiber(HBEDF) as a gain medium. The HBEDF is fabricated using a modified chemical vapor deposition in conjunction with solution doping. The fiber has an erbium ion concentration of 12500 ppm.At the optimum length of 0.5 m, the HBEDF amplifier(HBEDFA) achieves a flat gain of 26 d B with a gain variation of less than 1.5 d B within a wavelength region from 1530 to 1560 nm when the input signal and pump power are fixed at-30 d Bm and 140 m W, respectively. On the other hand, at the input signal power of-10 d Bm,the HBEDFA also achieves a flat gain of 14.2 d B with a gain variation of less than 2.5 d B within a wide wavelength region from 1525 to 1570 nm. Compared with the conventional zirconia erbium co-doped fiber based amplifier,the proposed HBEDFA obtains a more efficient gain and lower noise figure. For an input signal of-30 d Bm, the gain improvements of 6.2 d B and 4.8 d B are obtained at 1525 nm and 1540 nm, respectively.     

Applicability of winged bean extracts as organic corrosion inhibitors for reinforced steel in 0.5 ​M HCl electrolyte

Corrosion inhibition properties of winged bean (WB) extracts on reinforced steel in 0.5 ?M HCl solution was studied through experimental and theoretical calculation methods. The electrochemical studies suggested that inhibition efficiency increased with increasing concentration of WB extracts up to 95%. Nyquist diagrams revealed an increase in the charge transfer resistance values and a decrease in the constant phase element as the concentration of WB extracts were increased. The potentiodynamic polarization results revealed that WB extracts behave as mixed-type inhibitors, which physically adsorbed onto the reinforced steel surface. Effect of temperature study demonstrated that the corrosion resistance behaviour of WB extracts decreased with an increase in temperature, yielding a corrosion rate of 3.39 mmpy and 4.02 mmpy at 333 ?K with the incorporation of 1000 ?ppm WBW and WBE extracts, respectively. The thermodynamic study implied that the adsorption process follows the Langmuir isotherm with free energy adsorption of ΔG_ads WBW ?= ?-17.29 ?kJ ?mol^-1 and ΔG_ads WBE ?= ?-16.81 ?kJ ?mol^-1. Corresponding to the molecular modelling study, the semi-empirical method and molecular dynamics (MD) simulation investigated the correlation between the inhibitor compounds and the metal surface. One of the phenolic molecule constituents (gallic acid) was chosen to establish the structural and electronic parameters responsible for the high inhibition efficiency. A greater E_binding of 0.181 (a.u.) indicates that gallic acid in WB extracts can easily bind with the Fe surface, thus projecting a higher inhibitory performance. Surface morphology study affirmed the effective adsorption of WB extracts onto the surface of reinforced steel.     

Beam characterization and spatial coherence measurement of F2 laser using Lumilass glass fluorescence

This paper presents the spectral emission and saturation properties of a Lumilass G9 fluorescence glass excited using a 157 nm laser emitting ∼10 ns duration pulses. This fluorescence glass can be applied in conjunction with a CCD array for beam profiling and divergence measurements. This method can also be used for deriving information on the spatial coherence function of the F₂ laser. This constitutes one of the major contributions of the paper and is also discussed.     

Synthesis of a Negative Photochrome with High Switching Quantum Yields and Capable of Singlet-Oxygen Production and Storage

A dimethyldihydropyrene (DHP) photochromic unit has been functionalized by donor (triphenylamine group) and acceptor (methylpyridinium) substituents. This compound was characterized by NMR, absorption and emission spectroscopies as well as cyclic voltammetry, and its properties were rationalized by theoretical calculations. The incorporation of both electron-donor and -withdrawing groups at the photochromic center allows i) an efficient photo-isomerization of the system when illuminated at low energy (quantum yield: Φ_c-o=13.3 % at λ_ex=660 nm), ii) the reversible and quantitative formation of two endoperoxyde isomers when illuminated under aerobic conditions at room temperature, and iii) the storage and production of singlet oxygen. The photo-isomerization mechanism was also investigated by spin-flip TD-DFT (SF-TD-DFT) calculations.     

Sorption and dilation of silicone elastomer composites at high gas pressures: The role of interfacial quality

In elastomers the crosslink density, the presence of filler particles, and the volumetric confinement toward sorptive dilation can influence the extent of gas mass uptake. In this study the effects of filler particles on the high-pressure gas mass sorption and the volumetric dilation of a silicone elastomer matrix has been investigated. Glass beads, ca. 30 μm radii, with different surface treatments were incorporated as inclusions in various specimens at relatively low concentrations of ca. 10% by volume. The high-pressure gases used were N₂ and CO₂ up to a maximum ambient pressure of ca. 25 MPa at ca. 20°C and 42°C, respectively. The gas mass sorption was determined by a vibrating reed technique. The sorptive dilation was measured by an ultrasonic transducer operating as a displacement probe. In certain systems the absorbed CO₂ gas was able to disrupt the internal interfaces. This led to an increased gas mass uptake in the corrupted specimen. The N₂ gas did not affect the interfacial bonds. The amount of penetrant uptake was found generally to be reduced when the internal interfaces were not disrupted. The presence of various internal interfaces restrained the sorptive dilation of the elastomeric matrix. These hindrances to the natural sorptive dilation of the elastomer network suppressed the extent of the gas sorption process. This effect has also been investigated separately in detail using model ‘poker chip’ type of specimens of various aspect ratios. The sorptive dilational characteristics have been correlated with the mechanical properties of similar specimens. The influence of an almost complete volumetric confinement on the gas sorption capacity of the silicone elastomer specimen has also been studied. © 1992 John Wiley & Sons, Inc.     

Dissolution and Delignification of Bamboo Biomass Using Amino Acid-Based Ionic Liquid

In the present work, the dissolution of bamboo biomass was tested using a number of ionic liquids synthesized in laboratory. It was observed that one of the synthesized amino acid-based ionic liquids, namely 1-ethyl-3-methylimidazolium glycinate, was capable of dissolving the biomass completely. The dissolved biomass was then regenerated using a reconstitute solvent (acetone/water) and was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The results were compared to preconditioned bamboo biomass. The regenerated biomass was found to have a more homogenous macrostructure, which indicates that the crystalline form and structure of its cellulose has changed from type Ι to type ΙΙ during the dissolution and regeneration process.     

Zerumbone Ameliorates Neuropathic Pain Symptoms via Cannabinoid and PPAR Receptors Using In Vivo and In Silico Models

Neuropathic pain is a chronic pain condition persisting past the presence of any noxious stimulus or inflammation. Zerumbone, of the Zingiber zerumbet ginger plant, has exhibited anti-allodynic and antihyperalgesic effects in a neuropathic pain animal model, amongst other pharmacological properties. This study was conducted to further elucidate the mechanisms underlying zerumbone’s antineuropathic actions. Research on therapeutic agents involving cannabinoid (CB) and peroxisome proliferator-activated receptors (PPARs) is rising. These receptor systems have shown importance in causing a synergistic effect in suppressing nociceptive processing. Behavioural responses were assessed using the von Frey filament test (mechanical allodynia) and Hargreaves plantar test (thermal hyperalgesia), in chronic constriction injury (CCI) neuropathic pain mice. Antagonists SR141716 (CB₁ receptor), SR144528 (CB₂ receptor), GW6471 (PPARα receptor) and GW9662 (PPARγ receptor) were pre-administered before the zerumbone treatment. Our findings indicated the involvement of CB₁, PPARα and PPARγ in zerumbone’s action against mechanical allodynia, whereas only CB₁ and PPARα were involved against thermal hyperalgesia. Molecular docking studies also suggest that zerumbone has a comparable and favourable binding affinity against the respective agonist on the CB and PPAR receptors studied. This finding will contribute to advance our knowledge on zerumbone and its significance in treating neuropathic pain.     

Q-Switched Fiber Laser with a Hafnium-Bismuth-Erbium Codoped Fiber as Gain Medium and Sb2Te3 as Saturable Absorber

Journal of Russian Laser Research - We successfully demonstrate Q-switched fiber laser with a 20 cm long Hafnium-Bismuth-Erbium codoped fiber (HBEDF) as an active medium in conjunction with...