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Amorphous vanadium pentoxide (major phase) thin films of various thicknesses were grown on the substrates that possessed low (aluminized quartz) and high (quartz) infrared (IR) emittance property utilizing radio frequency (RF) magnetron sputtering technique. Microstructural characterizations are carried out by several techniques such as noncontact optical profilometry, energy dispersive X‐ray (EDX) spectroscopy, X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and X‐ray diffraction (XRD). The as‐grown amorphous films show stoichiometric vanadium oxide, where vanadium is in V5+ as a major proportion compared with V4+ states. Thermo‐optical properties, namely, solar transmittance (τs), reflectance (ρs), absorptance (αs) and IR emittance (εir) along with optical constant, for example, optical band gap, are evaluated. A modified Urbach equation was used to simulate the optical absorption data to understand the presence optical absorption below the band edge. [ABSTRACT FROM AUTHOR]

Aim: To investigate the relationship between changes in urine output during indomethacin treatment and ductal closure in preterm neonates.Methods: It is a retrospective study in neonates ≤32 weeks who had received two courses of indomethacin for PDA treatment over a 5-year period. Indomethacin courses with pre- and post-echocardiography confirmation of PDA status were included. Various urine output indices were collected and compared between successful versus unsuccessful indomethacin courses. Indomethacin treatment success was defined as: (i) where PDA closed or became haemodynamically insignificant (hisPDA) after treatment and (ii) only including neonates where PDA had complete closure after treatment. ROC analysis was performed to examine predictive ability of urine output during indomethacin for treatment success.Results: One hundred and eight indomethacin courses (first course: 52, second course: 56) in 80 neonates were included. The mean gestational age and birthweight were 25.4 ± 1.3 weeks and 762 ± 165 g, respectively. Irrespective of the definition used, there was no significant differences seen in any of urine output parameters between groups, except for a higher urine output during indomethacin associated with complete PDA closure (3.6 ± 1.3 vs. 3.0 ± 1.0 mL/kg/h, P = 0.02). The incidence of significant oliguria, hyponatraemia and need to withhold/delay indomethacin doses were also similar across groups.Conclusion: Urine output was not a useful predictor of ductal response to indomethacin treatment in preterm neonates. [ABSTRACT FROM AUTHOR]

Molybdenum doped vanadium oxide film on quartz and silicon substrates are grown by pulsed RF magnetron sputtering method. Surface morphology, phase analysis and oxide states are investigated by field emission scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy techniques, respectively. Crystalline nature of the film deposited on both quartz and silicon are depicted. The transmittance and reflectance spectra recorded for the entire solar region. Further, optical constants viz. optical band gap and refractive index of the deposited films are estimated. Wavelength dependent low reflectance characteristic is observed for the deposited film on silicon. IR emittance (εIR) and sheet resistance (Rs) of the film are also evaluated. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The present work reports a simple, inexpensive method for synthesis of calcium hydroxide [Ca( OH)2] nanoparticles ( CHNPs). The method involves chemical precipitation (CP) in aqueous medium at room temperature. Calcium nitrate dihydrate [Ca( NO3)2.2H2O] and sodium hydroxide were used as precursors. The CHNPs were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Rietveld analysis, field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), BET surface area evaluation as well as particle size distribution analysis techniques. The results confirmed the synthesis of CHNPs as the major phase. The CHNPs exhibited an average size of about 350 nm. In addition, some calcite phase formed due to the inevitable carbonation process. A very minor amount of aragonite phase was also present. A schematically developed new qualitative model is proposed to explain the genesis and subsequent evolution of the various phases at the nanoscale. The model helps to identify the rate-controlling step. It also highlights the implication of reaction kinetics control in synthesis of predesigned nanophase assembly. [ABSTRACT FROM AUTHOR]

Sunshield membranes made of germanium‐coated black polyimide (GBP) or Kapton are often used on the reflector/transmitter antenna of satellites for thermal control applications. However, the germanium top layer is prone to degrade during ground storage and implementation. Hence, vacuum/inert gas‐sealed packaging is required for storing the membranes, followed by a staggered fabrication schedule as the shelf‐life of the GBP is identified as only ~6 months. In the present study, microstructural, thermo‐optical, and electrical properties along with X‐ray photoelectron spectroscopy (XPS) studies for evaluating oxidation states of the as‐received and degraded GBP films have been investigated thoroughly. The radio frequency (RF) loss behavior of both the films has also been studied for S band (2.5–3.5 GHz), Ku band (10.5–14.5 GHz), and Ka band (30–35 GHz). Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Here, we present the results of nanoindentation experiments conducted at ultralow peak loads of, for example, 1000, 5000, and 10,000 μN on a dense (~99.5%), coarse grain (~10 μm) alumina ceramic. The results showed that the nanohardness values of alumina were sensitive to the applied loads as well as to the locations of measurements, for example, the center of the grain, away from the center of the grain and at the vicinity of the grain boundary. The location sensitivity of nanohardness was linked to compositional variations of the different locations and to the presence of an amorphous phase. [ABSTRACT FROM AUTHOR]

Hydroxyapatite coating was developed with high degree of crystallinity on SS316L substrate by the microplasma spraying technique. Systematic in vitro study of the coating was conducted after the immersion into the simulated body fluid for 1-14 days. Inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, Fourier transformed infrared spectroscopy, and scanning electron microscopy were utilized for physicochemical and microstructural characterizations. Nanoindentation technique employed to evaluate the nanohardness and Young's modulus of the coating at a constant load of 100 mN. Further, the tribological characteristic was also examined by microscratch testing at a ramping normal load of 10-10.6 N. [ABSTRACT FROM AUTHOR]

Many advanced applications of glass demand fabrication of engineering parts of utmost dimensional precision which require very accurate grinding and polishing that involves controlled removal of glass. Despite the wealth of literature, however; the mechanism of material removal in glass grinding and polishing is still far from well understood. For instance, it is not known at all to what extent the mechanical properties are compromised inside a scratch groove so as to optimize the machining parameters. Therefore, to develop better understanding about the mechanism of material removal, a series of combined nanoindentation and single pass scratch experiments were conducted on a commercially available soda-lime-silica glass as a function of various normal loads (2-20 N) and scratch speeds (0.1-1 mm/s). It was found that the nanohardness and Young's modulus at the local microstructural length scale inside the scratch groove could decrease quite dramatically (~30% to 70%) depending on the combination of load and scratching speed. Further, the tribological properties, the severity and the spatial density of damage evolution were sensitive to the normal loads, scratching speeds, and tensile stresses. Extensive scanning electron microscopy leads to interesting observations on material removal mechanisms. These observations were explained by the theoretical predictions of a model for a brittle, microcracked solid. [ABSTRACT FROM AUTHOR]

Structural and mechanical reliability of glass for both conventional and advanced applications is determined by the rate at which it can deform and sustain externally applied static or dynamic strain at the microstructural length scale. Hence, a large number of nanoindentation experiments were conducted on a thin (∼300 μm) commercial soda lime-silica glass with a 150 nm radius Berkovich tip at a constant load of 10,000 μN as a function of variations in the loading rates in the range of 10-20,000 μN/s. The results showed that the nanohardness of the soda lime-silica glass increased by as much as 74% as the loading rate was increased from 10 to 20,000 μN/s. Further, the presence of serrations in load-depth plots and deformation band formations inside the nanoindentaion cavities were more vividly observed in the nanoindentation experiments conducted at lower loading rates rather than those conducted at higher loading rates. These results are explained in terms of shear stress acting underneath the indenter as well as the time scale of interaction between the nanoindenter and the weak links at local microstructural length scale, which owe their origin to the subtle variations in the composition of the given glass. [ABSTRACT FROM AUTHOR]

We report the fracture toughness ( K) measured by nanoindentation technique at five different loads in the range of 100-1000 mN on the cross section of a highly porous microplasma-sprayed hydroxyapatite (MIPS-HAP) coating. The unique advantage of this technique was that it could evaluate K at a scale comparable with that of the local microstructure of the coating. In spite of high porosity (∼11 vol%), the coating showed a toughness (∼0.6 MPa m) comparable to typical literature data (∼0.5 MPa m) on dense HAP coating. Scanning electron microscopy of nanoindents suggested some plausible reasons for achieving a relatively higher toughness in the coating. [ABSTRACT FROM AUTHOR]

2D carbon fiber (C-fiber)-reinforced carbon/carbon (C/C) composites were prepared by vacuum infiltration with coal-tar pitch followed by carbonization and graphitization in inert atmosphere. Liquid silicon infiltration was done in controlled atmosphere at 1600°C to convert the matrix carbon of the C/C composites into silicon carbide. The 2D C/C and carbon/carbon-silicon carbide (C/C-SiC) composites had density of ∼1.65 and ∼2.32 g/cm, respectively with corresponding flexural strength of ∼70 and ∼169 MPa, respectively. The local mechanical properties like hardness, Young's modulus, contact pressure, relative stiffness, relative spring back, and indentation energies of the two composites under different loading conditions were measured at an ultra low load of 10 mN using a nanoindentation instrument with a Berkovich indenter. The scatter in the data was treated in terms of the two-parameter Weibull statistical analysis. The maximum characteristic Young's modulus (∼16 GPa) and hardness (1.20 GPa) was obtained for the C/C-SiC composites in parallel direction of fabric stacking. The elastic rebounce was also the maximum (0.77) for the C/C-SiC composites when loaded in parallel direction of fabric stacking. The extent of structural anisotropy was higher in the C/C-SiC composite than that of the C/C composite. [ABSTRACT FROM AUTHOR]