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The high explosive PBX 9502 undergoes irreversible expansion during thermal cycling ("ratchet growth"). Recent innovations in thermomechanical modeling via homogenization strategies are beginning to incorporate mesoscale information such as grain size, total porosity, and spatial distribution of voids and cracks. To generate a complete experimental data set to challenge and inform these models, PBX 9502 pellets were thermally cycled, cross-sectioned using ion polishing, and imaged in high resolution with scanning electron microscopy. Ratchet growth was found to drive expansion through microcracking. Microcracks were affected by agglomeration of crystals within the PBX. Virgin material showed greater ratchet growth than recycled material. [ABSTRACT FROM AUTHOR]

Herein we demonstrated the preparation of sulphur-doped graphene (SG) prepared via hydrothermal route. The resulted material is used for making highly sensitive and selective electrochemical sensor platform for accurate quantification of Hydrogen Peroxide (H2O2). Structural features and surface morphology of synthesised materials are fully examined using High resolution Transmission electron microscopy (HRTEM), Scanning electron microscopy (SEM), FT-IR and Raman spectroscopy techniques. In addition to that, electrochemical techniques like cyclic voltammetry (CV) and chronoamperometry (CA) are used to quantify the electron transfer kinetics and electro catalytic activity, these results inveterate it is due to strong electron donating ability of doped sulphur (S) atom and edge plane sites in SG that promotes the electron transfer process at electrode-electrolyte interface. The SG modified glassy carbon electrode (SG/GCE) exhibited finite selectivity; sensitivity stability with a regression coefficient (R2) value is 0.99 towards H2O2 estimation. The above observation conclude that these results are finest report to scrutinise the electrochemical properties of Graphene network by doping with Sulphur atom and it served as an important benchmark for the development of inexpensive SG based sensor platforms for electrochemical biosensor applications. [ABSTRACT FROM AUTHOR]

The effect of vacancies on the evolution of strain-induced NbC precipitates (SIP) was studied in a model austenitic Fe–30Ni–0.1Nb-0.1C steel deformed at 925 °C. Precipitation growth and coarsening characteristics have been investigated in detail by employing high resolution transmission electron microscopy. In general, the SIP preferentially nucleated on the nodes of the periodic dislocation networks constituting microband walls and grew over the varying holding time following the conventional precipitation growth and coarsening theory. Nevertheless, the current results demonstrated unexpected sluggishness in the process of growth and coarsening of the precipitates on the introduction of intermediary population of vacancies by a quenching step added in the thermomechanical processing schedules. It has been suggested that the formation of stable vacancy-solute complexes may reduce the effective availability of solutes for the precipitate growth. [ABSTRACT FROM AUTHOR]

In this research, we have presented detailed studies of the effect of temperature-controlled hydrothermal fabrication techniques on the morphology and structural strain in magnetoelectric core-shell nanocomposite having magnetic CoFe2O4 core coated with a piezoelectric BaTiO3 shell. We have presented the effect of controlled cooling rate during annealing process of synthesis on the structural integrity and structural strain of the core-shell hetero-nanostructure. Using temperature controlled hydrothermal method, it has been observed that controlling the cooling rate to 20 °C/min while annealing process leads to low structural strain on the deposited BaTiO3 shell. This also leads to high structural integrity of the fabricated heterostructure nanocomposite. To measure the strain distribution in the coated shell, geometric phase analysis was performed on the high-resolution transmission electron microscopic image of the fabricated core-shell nanostructure. Semi quantitative Energy-dispersive X-ray spectroscopy line scan elemental mapping have confirmed the elemental distribution throughout the nanostructure and formation of the core–shell structure. Moreover, through the geometric phase analysis, the core and the shell can be distinctively visualized which confirms the homogeneity of the coating of single crystalline BaTiO3 shell on the CoFe2O4 core. [ABSTRACT FROM AUTHOR]

We report the synthesis of graphene oxide/nickel oxide/β-cyclodextrin (GO/NiO/β-CD) nanocomposite and the efficiency of the nanocomposite in decolourising two different dyes, methylene blue (MB) and methyl violet (MV). GO was prepared by modified Hummer's method while hydrothermal method was used for the preparation of GO/NiO/β-CD. The as-synthesised nanocomposites were characterised by X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and high resolution transmission electron microscopy (HR-TEM). Photocatalytic degradation was carried out under solar light by monitoring the concentration of MB and MV dyes. Degradation reaction followed Langmuir-Hinshelwood pseudo first-order kinetic model. The apparent reaction rate constant (k) for MB increased as compared to MV under solar light irradiation. The MB showed better photocatalytic degradation efficiency by GO/NiO/β-CD composites. GO/NiO/β-CD nanocomposite has been very favourable for photocatalytic application. [ABSTRACT FROM AUTHOR]

Tetragonal SmVO4 nanorods were prepared by simple solvothermal route with various temperatures. An optimised SmVO4 sample was characterised through X-ray diffraction spectrum (XRD) and Micro-Raman spectroscopy. These results confirm that high crystallinity and pure tetragonal phase of SmVO4 can be achieved. For morphology analysis, scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDX) and selected area electron diffraction (SAED) techniques were performed. These results confirmed the rod shape SmVO4 nanoparticles with no impurities. For optical properties, UV-visible spectroscopy and photoluminescence (PL) techniques were performed. A broad absorption (290 nm – 330 nm) occurred in UV-Vis spectrum leads to multiple excitations and emissions at 542.7 nm, 600.5 nm and 643.7 nm with 4G5/2→6H5/2 (green), 4G5/2→6H7/2 (orange) and 4G5/2→6H9/2 (red), respectively. Finally, Vibrating sample magnetometer (VSM) study showed that the prepared SmVO4 nanoparticles possessed paramagnetic nature with high retentivity of 366.06 emu. Electrochemical performance of SV1 electrode shows pseudocapacitance nature with high specific capacitance value of 310 F/g (1 A/g) from GCD. [ABSTRACT FROM AUTHOR]

The present study reports a novel technique to synthesise silica nanoparticles through modified sol-gel, ultrasonication, and hydrothermal routes. Physio-chemical and structural characterization was carried out using X-ray diffraction, high resolution scanning electron microscopy, energy dispersive spectroscopy, dynamic light scattering, Fourier transform infrared spectroscopy, ultraviolet-visible, and photoluminescence spectroscopy. The particle size determination revealed the spherical structure of nanoparticles with an average diameter of 85 nm and between 90-170 nm through HRSEM and DLS respectively. Stretching and vibration bands confirming the presence of SiO2 were obtained in FTIR analysis. Spectra from UV-vis and PL spectroscopy were obtained at a maximum wavelength of 233 nm and 555 nm respectively. The anti-microbial effect of SiO2 nanoparticles against E. coli and S. aureus bacteria revealed the appreciable response which renders them for many biomedical applications like drug delivery. The cytotoxicity of SiO2 nanoparticles on human lung epithelial (A549) cell line revealed their non-toxic behavior. [ABSTRACT FROM AUTHOR]

Metal carbides MC (HfC, NbC, ZrC, TaC and TiC) that were exposed to air under the ambient temperature condition for a period of time were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) and Raman. Fresh MC samples exposed to the air for different time (fresh, one day, one week and one quarter) illustrated unexpected oxidation degree of the surfaces. XRD tests provided very limited information, since the oxidation process occurred from the surface at the nanometer scale. However, the XPS tests provided more comprehensive information for the MOx (HfO2, ZrO2, Nb2O5, Ta2O5 and TiO2) film and MC (HfC, NbC, ZrC, TaC and TiC) interlayer. Meanwhile, the HRTEM and Raman tests could give some additional or supporting information for XPS tests, when the samples were exposed to the air for longer time (one week or one quarter). Meanwhile, this research is the first to show that the oxidation progress of the metal surfaces of HfC, NbC, ZrC, TaC and TiC can take place in air under the ambient temperature condition and the oxidation film is about 2–5 nm. Meanwhile, a new oxidation mechanism of metal carbides MC (HfC, NbC, ZrC, TaC and TiC) exposed to air under the ambient temperature condition is also proposed, considering the obtained Raman, TEM and XPS results that could clearly confirm the formation of HfO2 and free carbon. [ABSTRACT FROM AUTHOR]

To study the effect of polyethylene glycol capping on structural, optical and thermal properties, ZnS:Ni2+ nanoparticles have been prepared by chemical precipitation method. It is demonstrated that by varying the concentration of PEG the particle size can be varied within ∼3.58 to 12 nm. To analyze the samples of nanostructures, the samples are subjected to X-ray diffraction, Field emission scanning electron microscopy and High resolution transmission electron microscopy characterization techniques. The spectral bands between 673 and 494 cm−1 are related to Zn-S stretching vibrations which was confirmed by Fourier transform infrared spectral studies. It is found that the uncapped sample emits strong UV light, whereas the capped samples exhibit strong and broad visible emission. An enhancement of fluorescence intensity has been obtained, in a capped sample with the minimum particle size and thus with more defect centers, in comparison to that of uncapped one. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is a sp2 hybridized carbon atom arranged in a honeycomb lattice. Graphene is a new allotrope of carbon compound which could prime new openings in research fields. GO was successfully synthesized via Phyllanthus Emblica (PE) leaf. Structures, morphologies and photo catalytic activities of the as synthesized nanomaterial were determined by using X-Ray diffraction (XRD), UV-Visible spectroscopy, Field emission scanning electron microscopy (FE-SEM), Energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), High resolution transmission electron microscopy (HRTEM) analysis. The photo catalytic activities of the as-synthesized GO were estimated for the degradation of malachite green (MG) and methyl violet (MV) in aqueous solution under replicated solar light. The photo catalytic degradation of GO was 94% for brilliant green and 99% for methyl violet in 120 min. [ABSTRACT FROM AUTHOR]

In this study, mullitisation at low temperature was observed in an oxime-modified aluminosiloxane precursor [(CH3)2CNO}2Al{OSi(Ph)2O}Al{ONC(CH3)2}2]. Oxime-modified aluminosiloxane was synthesised by carrying out a reaction between oxime-modified aluminium(III) isopropoxide [{(CH3)2CNO}2Al(OiPr)] and diphenylsilanediol in a 2:1 molar ratio. 29Si and 27Al NMR spectroscopic data suggest the presence of tetra- and penta-coordinated environment around Si and Al elements. The presence of Al-O-Si linkages was observed in the FTIR spectra of the precursor as well as in the formed mullite. Thermal study of precursor suggests clean decomposition of precursor molecules to amorphous aluminosilicate 3Al2O.2SiO2at ~500°C. Low temperature (900°C) transformation of precursor to mullite was observed by the sol-gel process. XRD (X-ray diffraction) and FTIR (Fourier Transform Infrared) studies suggest the formation of mullite in the orthorhombic phase without phase segregation. Scanning electron microscopy suggests agglomeration of nanocrystallite, while HRTEM (High Resolution Transmission Electron Microscopy) results corroborate with the XRD data. [ABSTRACT FROM AUTHOR]

Green nanotechnology stands amongst the leading giants of innovation for the twenty first century technological advances. More interesting, is the use of natural products as reducing agents. These could be recyclable materials from fruits and vegetables to produce nanoparticles (NPs) with novel properties. In the current study, silver NPs (AgNPs) were synthesized using the water extracts from the peel and flesh of two Pyrus communis L. cultivars, namely, the Forelle (Red) Pears (RPE) and Packham Triumph (Green) Pears (GPE). The AgNPs were characterized by UV-Vis spectrophotometry, Dynamic Light Scattering (DLS), High Resolution Transmission Electron Microscopy (HRTEM) and Fourier Transform Infra-Red Spectroscopy (FTIR). The antibacterial activities of the AgNPs were evaluated using agar well diffusion and microdilution assays. The cytotoxicity of the AgNPs was investigated on a rat macrophage (RAW 264.7) cells using MTT assay. Both the RPE and GPE were capable of synthesizing the AgNPs at high temperatures (70 and 100 °C). The AgNPs exhibited antibacterial activity against the test strains, and also had low toxicity towards the RAW 264.7 cells. Thus, the synthesized AgNPs have a potentially viable use in bio-applications for treatment of bacterial infections. [ABSTRACT FROM AUTHOR]

Organic dyes are mostly used in textile, paper, cosmetic, pharmaceutical industries etc., as colouring agents and being disposed in the environment that makes serious health issues. Therefore, this study has focused to the green synthesis of silver nanoparticles (Ag NPs) using AgNO3 and Punica granatum seeds extract as reducing/capping agent. The plasmonic absorption of obtained silver nanoparticles were observed at 440 nm which assured Ag NPs. Further, the crystalline nature and FCC (face centered cubic) pattern of Ag NPs was confirmed by XRD analysis. The spherical morphology with size 10 to 35 nm of Ag NPs were determined through HRTEM (high resolution transmission electron microscopy) analysis. These Ag NPs have been used as green catalyst to facilitate the reduction of organic pollutants/dye such as 4-nitrophenol and methyl orange in the presence of aq.NaBH4. This method is considered as eco-friendly and energy efficient for the environmental remediation under the concept of green chemistry. [ABSTRACT FROM AUTHOR]

The present work was conducted to biofabricate silver nanoparticles (AgNPs) in single step employing aqueous extract of Dregea volubilis flowers and to investigate its antioxidant, antidiabetic and antibacterial activities. The AgNPs were characterized by UV-Visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectrometry, high resolution transmission electron microscopy (HRTEM) and zeta potential study. The biofabricated AgNPs showed potential antioxidant activity for scavenging DPPH radical (IC50, 40.45 ± 5.06 μg/mL), ABTS radical (IC50, 78.49 ± 1.41 μg/mL), total antioxidant capacity (148.83 ± 2.99 mg GAE/g) along with remarkable inhibitory effects on α-amylase (IC50, 10.62 ± 0.22 μg/mL) and α-glucosidase (IC50, 6.49 ± 0.03 μg/mL). The AgNPs showed notable antibacterial activity in terms of zone of inhibition (in mm) against Pseudomonas aeruginosa (10.67 ± 0.44), Escherichia coli (9.33 ± 0.44), Bacillus subtilis (14.67 ± 0.60) and Staphylococcus aureus (15.67 ± 0.60). [ABSTRACT FROM AUTHOR]