Assessment of chemically characterised Rosmarinus officinalis L. essential oil and its major compounds as plant‐based preservative in food system based on their efficacy against food‐borne moulds and aflatoxin secretion and as antioxidant

The study explores antifungal, anti‐aflatoxigenic and antioxidant efficacy of Rosmarinus officinalis essential oil (ROEO) and its major compounds. In addition, the mode of action of ROEO and its practical efficacy as preservative have been assessed. GC‐MS analysis of ROEO identified 16 compounds; α‐pinene, 1,8‐cineole and camphor being the major compounds. The minimum concentration for inhibition of growth and aflatoxin B₁ secretion against A. flavus (LHP‐6) was found to be 1.5, >5.0, 4.0 and 3.0 μL mL^?1 and 1.25, >5.0, 3.5 and 3.0 μL mL^?1 for ROEO, α‐pinene, 1,8‐cineole and camphor, respectively. The IC₅₀ value through DPPH analysis and percentage inhibition of linoleic acid peroxidation of ROEO were 0.042 μL mL^?1 and 71.05%, respectively. The targeted site of antifungal action of ROEO was confirmed as plasma membrane through ergosterol measurement and TEM analysis. Moreover, ROEO significantly protected Piper nigrum fruits against mould infestation upto 6 months in in vivo trial.     

Extraction,multi-response analysis,and optimization of biologically active phenolic compounds from the pulp of Indian jamun fruit

An aqueous extraction technique was applied to optimize the extraction process variables of temperature (40°C–60°C), time (20–100 min), and the solid-to-liquid ratio (1:10–1:15) using a Box-Behnken experimental design and response surface methodology. Maximum extraction yields of total phenolics and flavonoids, and anti-oxidant activities were obtained from Indian jamun fruit. Effects of the extraction temperature and the solid-toliquid ratio were found to be significant (p<0.05) for all responses. Second order polynomial models were developed from experimental data to predict the effects of the independent variables on the responses. Optimum extraction conditions (temperature of 54°C, time of 50 min, and a solid-to-liquid ratio of 1:8.5) for the maximum extraction yield of total phenolics (1,332.36 mg GAE/100 g) and flavonoids (110.94 mg QE/100 g), and the anti-oxidant activity (233.55mg AAE/100 g) were achieved. Experimental values matched well with predicted values obtained under optimum conditions.     

Role of Superficially Applied SnO2 Inhibitor in Controlling High Temperature Corrosion of Some Fe-, Co- and Ni-Base Superalloys

Inhibitors and fuel additives have been used with varying success to combat high temperature corrosion of metals and alloys. In this work, the role of a superficially applied SnO₂ coating to combat high temperature corrosion of some superalloys viz Superfer 800H (Alloy A), Superco 605 (Alloy B) and Superni 75 (Alloy C) has been investigated. Accelerated corrosion testing of the coated as well as bare superalloys was done in a molten salt environment (Na₂SO₄–60 %V₂O_5?) at 900 °C for 50 cycles. Each cycle consisted of 1 h heating in a silicon carbide tube furnace followed by 20 min cooling in ambient air. Weight change measurements after each cycle were taken by an electronic balance having an accuracy of 0.01 mg. XRD, SEM and EPMA analyses of the exposed specimens were carried out to characterize the oxide scales. The bare superalloys showed more overall weight gains, in general, in comparison with their SnO₂ coated counterparts. The corrosion rate for the bare Co-base alloy was found to be highest, whereas that for the Fe-base Superfer 800H a lowest. The percentage decrease in the weight gain in alloys A, B and C with superficially applied SnO₂ was found to be 17.2, 66 and 50 % respectively after 30 cycles. The effectiveness of the SnO₂ was perhaps due to its non-reactive nature with the corroding species and high melting point (1630 °C).     

Hot Corrosion Behavior of Some Superalloys in a Simulated Incinerator Environment at 900 °C

Incinerators are being used to burn solid waste of all types. This burning of waste creates a very aggressive environment at extremely high temperature. This environment attacks the various components of the incinerators. Some studies have been reported regarding behavior of steels in simulated incinerator environment at 550 °C. In present work superalloys Superco 605, Superni 600, and Superni 718 have been subjected to cyclic oxidation in 40 wt.% K₂SO₄ + 40 wt.% Na₂SO₄ + 10 wt.% KCl + 10 wt.% NaCl environment at 900 °C under cyclic condition. Weight change measurements have been done and weight change has been plotted against the numbers of cycles. The oxide scales formed on the surface of the corroded superalloys have been characterize by FESEM, EDS, XRD, cross-sectional analysis, and x-ray mapping. The nickel-based superalloys Superni 600 and Superni 718 indicated better resistance to corrosion in the above environment whereas Superco 605 lead to massive weight gain.     

Quantum and dielectric confinements of sub-10 nm gold in dichroic phosphate glass nanocomposites

Blue shifts of the surface plasmon resonance band of sub-10 nm gold in dichroic phosphate glass nanocomposites are observed with increase in both size of gold nanoparticles and refractive index of the medium, which are contrary to the common trends. These phenomena have been enlightened with the electrodynamics theories (Mie and Drude models) and happened due to quantum and dielectric confinements. Nanocomposites have been synthesized by in-situ thermochemical reduction technique in reducing phosphate glass matrices. The plasmon bands are characterized by the UV–vis spectrophotometer, and shape and size of the nanogold by the transmission electron microscopy. All the nanocomposites are dichroic in nature.