Investigation of the secondary phases of Alloy 617 by Scanning Kelvin Probe Force Microscope

Alloy 617 (nickel based austenitic alloy) is a candidate structural material for next generation high temperature nuclear reactor. The secondary phases present in the Alloy 617 has been identified as TiN and M₂₃C₆ by optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). Surface potentials of these phases have been evaluated by Scanning Kelvin Probe Force Microscope (SKPFM). SKPFM investigation showed higher surface potential of the secondary phases than that of the austenite matrix. The surface potential of the TiN was nobler than that of M₂₃C₆ indicating that these precipitates could act as cathodic sites during oxidation reaction. Difference in the local chemistry of these phases results in variation of the chemical potentials, which in turn could lead to enhanced oxidation at localized areas in the vicinity of the secondary phase precipitates that act as cathodic sites.     

In vitro assessment of antimicrobial efficacy of the D-tagatose and lactobacilli-based synbiotic preparations against the pathogenic Escherichia coli and Salmonella typhimurium

The study aimed to investigate the utilisation of prebiotic D-tagatose by probiotic lactobacilli (L. rhamnosus GG, L. casei, L. acidophilus and L. fermentum) and enteric pathogens (E. coli and S. typhimurium) to determine synbiotic potential of D-tagatose and lactobacilli combination. The antimicrobial efficacy of the synbiotic preparations (D-tagatose with lactobacillus) was assessed against selected pathogens in co-culture assays. Evidently, D-tagatose supported growth of selected lactobacilli, especially the L. rhamnosus GG and L. casei, but not the enteric pathogens. The tested synbiotic preparations completely inhibited growth of both the pathogens, even in the presence of D-glucose in co-cultures. The well-diffusion assay demonstrated the presence of antimicrobial activity as recorded by drop of culture pH. The study substantiated that D-tagatose could be an effective prebiotic component for formulation of potential synbiotic combinations with L. rhamnosus GG or L. casei that can be used as an alternative to antibiotics against enteric pathogens.     

Structural and optical characterization of RE (Eu<Superscript>2+</Superscript>, Ce<Superscript>3+</Superscript>) doped SrMg<Subscript>2</Subscript>Al<Subscript>6</Subscript>Si<Subscript>9</Subscript>O<Subscript>30</Subscript> nanocrystalline phosphor

This article present the reports on optical study of Eu²⁺ and Ce³⁺ doped SrMg₂Al₆Si₉O₃₀ phosphors, which has been synthesized by combustion method at 550 °C. Here SrMg₂Al₆Si₉O₃₀:Eu²⁺ emission band observed at 425 nm by keeping the excitation wavelength constant at 342 nm, whereas SrMg₂Al₆Si₉O₃₀:Ce³⁺ ions shows the broad emission band at 383 nm, under 321 nm excitation wavelength, both the emission bands are assigned due to 5d–4f transition respectively. Further, phase purity, morphology and crystallite size are confirmed by XRD, SEM and TEM analysis. However, the TGA analysis is carried out to know the amount of weight lost during the thermal processing. The CIE coordinates of SrMg₂Al₆Si₉O₃₀:Eu²⁺ phosphor is observed at x?=?0.160, y?=?0.102 respectively, which may be used as a blue component for NUV-WLEDs. The critical distance of energy transfer between Ce³⁺ ions and host lattice is found to be 10.65 Å.     

Synthesis,characterization, and magneto‐electric properties of (1−x)BCZT‐xCFO ceramic particulate composites

Synthesis of a new magnetoelectric [(1?x)(Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃‐xCoFe₂O₄] (weight fraction x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1) ceramic particulate composites with its structural characterization and magneto‐electric properties have been reported here in this study. Lead free piezoelectric (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ (BCZT) and ferrimagnetic CoFe₂O₄ (CFO) were synthesized using sol‐gel and combustion methods respectively. (1?x)BCZT‐xCFO magnetoelectric composites were then synthesized by mixing of the calcined individual ferroic phases with required weight fractions. Powder X‐ray diffraction studies indicate the coexistence of BCZT and CFO phases in the composites sintered at 1300°C. 0.5BCZT‐0.5CFO composite showed high strain sensitivity (dλ/dH) of 52×10^?9 Oe^?1, which is comparable to that of pure CFO (50×10^?9 Oe^?1). A high piezoelectric voltage constant (g₃₃) of 8×10^?3 V m/N was measured for 0.8BCZT‐0.2CFO sample. All the composites showed magnetoelectric effect and a high magnetoelectric coupling coefficient (α_ME) of 6.85 mV/cm Oe was measured for 0.5BCZT‐0.5CFO composite at 1 kHz and a large ME coefficient of 115 mV/cm Oe at its resonance frequency. The effect of microstructure on the magnetoelectric properties of [(1?x)BCZT‐(x)CFO] composites has been studied and reported here as a function of its piezoelectric (BCZT)/ferrite (CoFe₂O₄) content.     

Giant magnetocapacitance in magnetoelectric BNT/NFO particulate composites

Journal of Materials Science: Materials in Electronics - Bi0.5Na0.5TiO3 (BNT) and NiFe2O4 (NFO) ceramics were synthesized using the sol–gel method. Further, a series...     

A software metric system for module coupling

Low module coupling is considered to be a desirable quality for modular programs to have. Previously, coupling has been defined subjectively and not quantified, making it difficult to use in practice. In this article, we extend previous work to reflect newer programming languages and quantify coupling by developing a general software metric system that allows us to automatically measure coupling. We have precisely defined the levels of coupling so that they can be determined algorithmically, incorporated the notion of direction into the coupling levels, and accounted for different types of nonlocal variables present in modern programming languages. With our system, we can measure the coupling between all pairs of modules in a system, measure the coupling of a particular module with all other modules in a system, and measure the coupling of an entire system. We have implemented our metric system so that it measures the coupling between pairs of procedures in arbitrary C programs and have analyzed several well-used systems of various sizes.     

Production and in vitro evaluation of xylooligosaccharides generated from corn cobs

Corn cobs are major byproduct of maize processing industries. For value addition of maize byproducts, the present paper aims at extracting xylan from corn cobs and subsequent production of xylooligosaccharides (XOS). Compositional determination of corn cobs revealed 38.78% hemicellulose, 27.71% cellulose and 9.4% lignin. Recovery of xylan increased with increasing concentration of alkali during extraction. The extracted xylan was subjected to acidic hydrolysis to yield XOS. HPLC analysis of hydrolysate revealed increased production of XOS with time, but prolonged incubation resulted in higher amount of xylose. Four probiotic strains were used for undertaking in vitro evaluation of the prebiotic efficacy of XOS. XOS ensured higher growth rate for Enterococcus faecium as compared to other probionts, while fructooligosaccharides (FOS) supported higher proliferation of Lactobacillus viridiscens. This method of xylan extraction and production of XOS offers scope for value addition to the corn byproducts.     

Application of radioactive tracer technique for characterization of strongly basic anion-exchange resins duolite A 101D and duolite A 102D<Superscript>1</Superscript>

The radioactive ⁸²Br was used as a tracer to study the bromide self-diffusion reactions. The effect of temperature, concentration of ionic solution, and amount of ion-exchange resin on the kinetics of exchange reactions was examined. Under identical experimental conditions, the specific reaction rate, amount of bromide ions exchanged, and initial rate of bromide ion exchange calculated for Duolite A 101D resin were higher than those calculated for Duolite A 102D resin. The difference in the values calculated for the two resins was attributed to their water-holding capacities. The probable mechanism of bromide isotope exchange reaction was also predicted by comparing the specific reaction rate of rapid and slow exchange process. It is expected that the same technique can be employed to assess the efficiency of various ion exchangers under different operating conditions.     

Growth of pseudocubic perovskite-type SrRuO3 thin films on quartz substrate using pulsed laser deposition method

Strontium ruthenium oxide (SrRuO₃) thin films have been grown using pulsed laser deposition technique on silicon, Pt coated silicon and quartz substrates. The effect of substrate temperatures on the structural, microstructure, and electrical properties of the SrRuO₃ films on quartz substrate has been investigated using XRD, SEM, AFM and four-probe method, respectively. The lowest resistivity at room temperature for the SrRuO₃ thin film on quartz substrate has been achieved at substrate temperature of 700 °C. Furthermore, the comparisons of SrRuO₃ thin films deposited on various substrates have been done with respect to structural, microstructural and electrical properties. XRD patterns exhibit that all thin films are a single phase, pseudo-cubic perovskite structure. Study of surface morphology shows that grain size and roughness varies with respect to substrate. It is observed that SrRuO₃ thin films yield larger grain size and root mean square roughness on Pt/Si substrate. Investigation of electrical properties shows that SrRuO₃ thin films can serve the purpose of the bottom electrode in dielectric and ferroelectric devices.