MgNb2O6:Dy3+ nanophosphor: A facile preparation,down conversion photoluminescence and UV driven photocatalytic properties

Series of (1–9 mol %) dysprosium (Dy³⁺) ions doped MgNb₂O₆ (MNO) nanophosphors were synthesized by chemical combustion process and their photo luminescent and photocatalytic behaviours were examined. Powder X-ray diffraction (PXRD) reveals the columbite structure and crystal structure parameters were calculated. The average crystallite size was found to be in the range of 20–30 nm as calculated by Scherrer's method. The photoluminescence (PL) of MgNb₂O₆:Dy³⁺ (λ_exc-393 nm) reflects white emission for the prepared samples as confirmed by CIE and CCT. The photocatalytic activities of these nanophosphors were probed for the decolorization of acid red 88 (AR-88) under UV light irradiation. The photocatalyst with MgNb₂O₆:Dy³⁺ (5 mol %) showed enhanced activity of 97%, attributed to effective separation of charge carriers. All the above experimental results confirm that, the optimized phosphor is quite useful for WLEDs, solid-state lighting applications and as a photocatalyst.     

MoSe2 nanoflowers as a counter electrode for quantum dots sensitized solar cells

Journal of Materials Science: Materials in Electronics - Layered transition metal dichalcogenides hold tunable and promising photoelectrochemical properties. MoSe2 is a potential candidate of the...     

Effects of activator characteristics on the reaction product formation in slag binders activated using alkali silicate powder and NaOH

The influence of different levels of alkalinity, expressed using the Na₂O-to-source material ratio (n) and activator SiO₂-to-Na₂O ratio (M_s), on the compressive strength development of, and reaction product formation in sodium silicate and NaOH powder activated slag binder systems is discussed. Higher n value mixtures are found to exhibit higher early and later age compressive strengths. An increase in M_s results in reduced early age and slightly increased later age strengths. Compositional coefficients, which are functions of n and M_s are proposed, that relate to the early and later age strengths of the activated slag binders as well as to the shift in the FTIR spectra. The reaction product formation in these systems as a function of the total alkalinity is explained using the shifts of the dominant peak in the FTIR spectra. Fundamental changes in reaction products of powder activated binders as a function of alkalinity is observed. The deductions from the peak shifts are substantiated using the FTIR spectra of the pastes before and after salicylic acid–methanol (SAM) attack.     

Machining Characteristics and Corrosion Behavior of Grain Refined AZ91 Mg Alloy Produced by Friction Stir Processing: Role of Tool Pin Profile

In the present study, influence of friction stir processing (FSP) tool pin profile on the microstructure evolution, corrosion and machining characteristics of the AZ91 magnesium alloy was investigated. Three different pin profiles namely simple taper, threaded taper and square taper were selected and FSP was carried out at 1400 rpm and 25 mm/min tool travel speed. Microstructural observations indicated grain refinement from a starting grain size of 166.5–7.9, 22.1 and 4.08 µm for FSPed samples processed by simple taper, threaded taper and square taper pins, respectively. In all the FSPed samples, decreased amount of secondary phase (Mg₁₇Al₁₂) was observed compared with that of the unprocessed sample. From the X-ray diffraction analysis, it was observed that the square taper pin tool had induced higher texture effect compared with the other two FSP tools. From the electrochemical studies, the corrosion resistance of the sample processed with square taper pin tool was observed to be more in comparison to that of the other samples; which could be attributed to the texture effect and decreased fraction of secondary phase. Machining behavior assessed by conducting drilling experiments showed a significant influence of grain refinement on the cutting forces.     

Expression characteristics of the maeA and maeB genes by extracellular malate and pyruvate in Escherichia coli

The malate-pyruvate conversion pathway is catalyzed by two malic enzyme isomers, MaeA and MaeB. qRT-PCR was carried out under malate and pyruvate supplemented conditions to understand the dynamics of maeA and maeB gene expression. maeA expression was elevated by malate, and maeB expression was inhibited by levels of both malate and pyruvate higher than 0.1 mM. Green fluorescent protein (GFP) reporter plasmids were also constructed by integration of the maeA/maeB promoter with the gfp gene. We showed that maeA driven GFP expression was positively and negatively correlated with extracellular malate and pyruvate induction. In contrast, no significant changes in maeB driven GFP expression were observed under both malate and pyruvate supplemented conditions.     

Crystal structure and characterization of a novel organic crystal: 4-Dimethylaminobenzophenone

Single crystals of a novel organic material, dimethylaminobenzophenone were grown from aqueous solution employing the technique of controlled evaporation. Dimethylaminobenzophenone belongs to the monoclinic system, with a = 12.5755(7) Å, b = 7.9749(4) Å, c = 13.0946(7) Å, α = 90°, β = 111.6380(10)° and γ = 90°. Fourier transform infrared study has been performed to identify the functional groups. The transmittance of dimethylaminobenzophenone has been used to calculate the refractive index n; the extinction coefficient K and both the real ?_r and imaginary ?_i components of the dielectric constant as functions of photon energy. The optical band gap of dimethylaminobenzophenone is 2.9 eV. The structural prefection of the grown crystals has been analyzed by high-resolution X-ray diffraction rocking curve measurements. Thermo gravimetric analysis and differential thermal analysis have also been carried out, and the thermal behavior of dimethylaminobenzophenone crystal has been studied. The dielectric properties and mechanical properties have been investigated.     

Phase precipitation and phase stability in nimonic 263

Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermodynamic calculations were employed to study the phase stability and phase precipitation in the Ni-based superalloy Nimonic 263. The major precipitates at temperatures below 900 °C were gamma-prime and eta (Ni₃Ti), with the eta phase starting to precipitate at the expense of the gamma-prime phase after prolonged annealing. The eta precipitates had a thin-plate morphology and formed a regular Widmanstätten pattern. They had a fixed orientation relationship with the fcc matrix. Very fine particles of M₂₃C₆ also precipitated intragranularly, and they had a cube-on-cube orientation relationship (OR) with the fcc matrix. Intragranular precipitation of a very fine cylindrical MC carbide was also observed. Grain-boundary (GB) precipitates were mostly M₂₃C₆, with a small fraction of MC. Based on the experimental results, a time-temperature-transformation (TTT) diagram was constructed. The experimental results were compared to thermodynamic predictions, and good agreement was observed. The calculations correctly predicted almost all the major phases and their stability temperature ranges. The experimental and calculation results, together, depict a clearer picture of phase stability in the alloy.     

Bubble temperature data for phenol-alcohol systems: Phenol-I-Amyl alcohol and phenol-n-Amyl alcohol systems

In order to supplement the literature data on VLE, isobaric bubble temperature data were collected for the binary systems phenol-i-amyl alcohol and phenol-n-amyl alcohol over the entire composition range by indirect method using a standard Swietoslawski type ebulliometer. The measurements were made at three sub-atmospheric pressures. The experimental t-x data were correlated with both equation of state method and gamma-phi methods. In the former approach, the Soave equation of state is used, whereas in the latter case Wilson, NRTL and UNIQUAC equations are used.