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Copper oxide (CuO) nanostructures have gained significance due to their chemical and physical properties that find applications in sensing, electronics and minimizing solar background count in spaceborne plasma instruments. In this work, a wet-chemical route has been utilized to synthesize nanostructured CuO coating on aluminum alloy substrates. The coating was thoroughly characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), Raman spectroscopy, glow-discharge optical emission spectroscopy (GDOES), UV-VIS-NIR spectrophotometer and four probe resistance methods. XRD results showed diffraction peaks corresponding to CuO while SEM micrograph depicted a floral-like nanostructure. Raman spectrum revealed phonon vibrational modes corresponding to CuO. The average solar absorptance of CuO nanostructure was 96% in the wavelength range of 0.25-2.5 μm. A comparison of the UV-induced photoelectron counts between the bare substrate and coated samples showed reduction by a factor of 107 due to the presence of CuO nanostructures. The CuO nanostructures also exhibited excellent electrical conductivity and low-degassing properties. Finally, space worthiness studies of the coating in simulated space environments was carried out and proven to be space qualified. [ABSTRACT FROM AUTHOR]

The present work explores the adaptive behavior of well-known ureolytic bacterial strain namely Sporosarcina pasteurii for microbial-induced calcite precipitation (MICP) under saline environment. MICP activity was observed up to 10% NaCl supplementation and confirmed by several characterization techniques viz. scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The urease activity did not show appreciable decline till 5% NaCl supplementation but beyond that drastic reduction was observed though MICP process continued. These results indicated a shift in the biological pathway for MICP process at higher salt concentrations. This was confirmed by estimation of ammonium ion concentration which was approximately 4 µg/ml with 10% NaCl supplementation as compared to 8.5 µg/ml at 0% NaCl supplementation. To provide an insight on the nature of protein expressed, combination of liquid chromatography-mass spectrometry (nano-LC-MS) approaches along with an exponentially modified protein abundance index (emPAI) methodology were explored. The findings suggest the presence of significant number of osmoregulatory proteins substantiating halophilic adaptation of S. pasteurii and bicarbonate transport mediated precipitation at higher levels of salinity. Further, co-precipitation of CaCl2 and MgSO4 was also confirmed with SEM and energy dispersive spectroscopy (EDS) mapping under higher saline environment thus substantiating the efficacy of the strain. [ABSTRACT FROM AUTHOR]

Vanadium oxide films, deposited on aluminium (Al), titanium (Ti) and tantalum (Ta) metal substrates by pulsed RF magnetron sputtering at a working pressure of 1.5 x10−2 mbar at room temperature are found to display mixed crystalline vanadium oxide phases viz., VO2, V2O3, V2O5. The films have been characterized by field-emission scanning electron microscopy, X-ray diffraction, differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy, and their thermo-optical and electrical properties have been investigated. Studies of the deposited films by DSC have revealed a reversible-phase transition found in the temperature range of 45–49 °C. [ABSTRACT FROM AUTHOR]

Present study reports the detailed nanomechanical and corrosion behaviours of crystalline and amorphous plasma electrolytic oxidation (PEO) coatings developed on Aluminium alloy-6061. The concentration of sodium silicate in the electrolyte is tailored to achieve crystalline and amorphous natures of the PEO coatings. X-ray diffraction (XRD), scanning electron microscopy (SEM) and nanoprofilometry techniques are utilized to investigate microstructural and morphological properties of the PEO coatings. XRD studies confirmed that crystalline ceramic phases are obtained at lower silicate concentration while amorphous nature occurred for comparatively higher concentration of silicate in the electrolyte. Nanoindentation technique is utilized to study the mechanical properties such as hardness (H) and Young's modulus (E) of the PEO coatings. The scatter of the data is treated with well-established Weibull statistical method. Finally, in depth corrosion behaviour of the coatings are investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. Amorphous coatings exhibited superior mechanical properties compared to the crystalline coatings. This is possibly linked with the presence of aluminosilicate phases and difference in silicon content in the coatings. However, as expected crystalline PEO coatings offer better corrosion resistance than the amorphous coatings and this behaviour is explained in terms of porosity contents of the coatings. [ABSTRACT FROM AUTHOR]

Abstract: Alumina thin films were deposited on titanium (Ti) and fused quartz by both direct and reactive pulsed rf magnetron sputtering techniques. X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy were utilized to study the phases and surface morphology of the films. The as-deposited alumina thin films were amorphous. However, after annealing at 500°C in vacuum, the crystalline peaks corresponding to the Theta (θ), Delta (δ) and Chi (χ) alumina phases were obtained. The optical transmittance and reflectance as well as IR emittance data were also evaluated for the thin films. The transmittance, e.g., (~90%) of the bare quartz substrate was not changed even when the alumina thin films were deposited for an hour. However, further increase in deposition time (e.g., 7h) of the alumina thin films showed only a marginal decrease (e.g., ~5%) in average transmittance of the bare quartz substrate. The direct and indirect optical band gaps and extinction coefficient of the alumina films were estimated from the transmittance spectra. The IR emittance of the Ti substrate (e.g., ~16%) was almost constant after depositing alumina thin films for an hour. Further increase in deposition time showed only a marginal increase (e.g., ~9%) in IR emittance value. Therefore, it is proposed that the alumina films developed in the present work can act as a protective cover for the Ti substrate while retaining the thermo-optical properties of the same. The nanohardness and Young׳s modulus of the alumina thin films were evaluated by the novel nanoindentation technique. The nanohardness was measured as ~6GPa. Further, Young׳s modulus was evaluated as ~116GPa. The magnitudes of the nanomechanical properties of the thin films were a little smaller than those reported in the literature. This was linked to the lack of crystalline phases in the as-deposited alumina thin films. [Copyright &y& Elsevier]