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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]

A simple sonication assisted green synthesis method was adopted to prepare nickel oxide nanoparticles using Moringa leaf extract as reducing agent and capping agent. The structural, optical, morphological, photocatalytic, and antimicrobial properties of NiO nanoparticles have been analyzed through different techniques X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and UV-vis spectrometer. The average crystallite size of NiO nanoparticles is 12 nm which is well matched with the particle size calculated from TEM micrographs. The FESEM and HRTEM micrographs clearly show the spherical shaped nanoparticles with uniform distribution. The multi-functional applications like anticorrosive, photocatalytic, and antimicrobial activity of NiO nanoparticles are also analyzed. The green synthesis influenced more in the performance of antibacterial activities of NiO nanoparticles for Staphylococcus aureus and Escherichia coli. [ABSTRACT FROM AUTHOR]

The present work describes the economical two-stages catalytic CVD method of the nanocomposite of phosphorous-doped multi-walled carbon nanotubes with nickel (Ni/P-MWCNTs) from the solution of the triphenylphosphine in ethanol using Ni/CaO catalyst. The structure of Ni/P-MWCNTs nanocomposite was studied by high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), X-ray diffraction (XRD), and nitrogen adsorption-desorption method. The Ni/P-MWCNTs nanocomposite are characterized as a mixture of the cylindrical and bamboo-like predominately closed nanotubes with an average outer diameter of 31 nm and SBET=186 m2/g. The P atoms covalently bonded to the carbon framework of the P-MWCNTs walls predominantly through the oxygen bridges. The metal was found in Ni(0) form on the P-MWCNTs tips that is only partially covered by graphene layers. The clusters of bulk Ni(NiO) was also detected in the sample. The glassy carbon electrode modified by the Ni/P-MWCNTs nanocomposite exhibit good electrocatalytic activity in the hexachlorobenzene stepwise degradation and showed an average potential shift of ∼200 mV and ∼130 mV for each stage to the less negative potentials compared to the unmodified glassy carbon electrode and glassy carbon electrode coated by undoped MWCNTs. [ABSTRACT FROM AUTHOR]

We aimed to understand the characteristics of bimetallic systems samples with porous and large surface areas. In doing this we studied in particular the surface structure of the Pd/Ag system. Our cluster models were based on high resolution transmission electron microphotographs of samples with defects. For the modelling of our Pd/Ag nano systems, we combined a variety of experimental and theoretical methods, such as: sputtering, acrylamide sol–gel, high resolution transmission electron microscopy, energy dispersive X-ray spectrometry, and density functional theory. This study explores the connection between nanocrystal structure, electron density distribution, and charge transfer. Charge transfer was determined via density difference analysis. Charge density as a function of the orbital radius was calculated. Vertical electron affinity, vertical first ionization potential, and vertical electronegativity of the Pd18 and Ag24 clusters were calculated. In addition, Voronoi, Bader, Becke, Loewdin, Mulliken, NPA, and NBO population analyses were conducted. [ABSTRACT FROM AUTHOR]

This investigation has been developed to determine which microstructural changes on the eutectic α-Ni-Ni3Si- monoclinic, if any exist, result from the irradiation with Ni-ions. SRIM program has been used to simulate the interaction of the irradiation with both α-Ni and Ni3Si- monoclinic phases. X-ray diffraction studies of irradiated and non-irradiated regions have allowed us to establish that the ion irradiation promote the formation of the Ni31Si12-hexagonal intermetallic phase with hexagonal structure. An analysis of the irradiated region by High Resolution Transmission Electron Microscopy (HRTEM) confirmed the presence of the Ni31Si12-hexagonal intermetallic phase, establishing at the same time, its crystallographic relationship with the matrix. Evidently, radiation-induced segregation could cause significant changes in the chemical composition of concentrated alloys. This experimental discovery, in particular, is significant because the formation of the Ni31Si12-hexagonal phase under irradiation conditions had never been mentioned before. Nonetheless, the formation of the Ni31Si12-hexagonal intermetallic phase represents an advance in the field of the microstructural modification by ion beam irradiation, and as a consequence of this finding, it is possible to establish that the structural stability of the eutectic form of the α-Ni-Ni3Si-monoclinic phases under severe irradiation conditions, is questionable. [ABSTRACT FROM AUTHOR]

Development of high-efficiency anode electrocatalysts remains a challenge for direct methanol fuel cells (DMFCs). Herein, carbon dots (CDs) and Co-substituted sandwich polyoxometalate K10[Co4(H2O)2(PW9O34)2]·20H2O (Co-POM) were selected as building blocks to construct a new ternary composite electrocatalyst CDs/Co-POM/Pt for application in the methanol oxidation reaction. CDs/Co-POM/Pt was characterized by FTIR, high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectrum (EDX), element mapping, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results revealed that a nanoflower-like Pt nanostructure with high dispersion and uniformity was formed. The electrochemical experiments showed that CDs and Co-POM enhanced the electrocatalytic ability of Pt, and the highest peak current density of 7.98 mA cm−2 was obtained for CDs/Co-POM/Pt, corresponding to 3.6 times, 6.5 times and 10.8 times as high as that of CDs/Pt, Co-POM/Pt and pure Pt. Also CDs/Co-POM/Pt had good stability in the electrocatalytic process. This work paves a way for development of polyoxometalate-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Pb(II) complexes of N-ethyl-N-phenyl dithiocarbamate [Pb(EtPhdtc)2] and N-benzylmethyl dithiocarbamate [Pb(BzyMedtc)2] were synthesized and characterized by single crystal X-ray crystallography. The molecular structures of compounds reveal a distorted tetrahedral geometry around the Pb(II) ions. [Pb(EtPhdtc)2] crystalized as a dimeric structure with Pb ... Pb and Pb ... S interactions while [Pb(BzyMedtc)2] crystallized as monomeric complex with weak C–H interactions. Thermogravimetric analysis of the Pb(II) complexes shows they decomposed to give lead sulphide (PbS). The complexes were thermolysed in oleic acid (OA) at 120°C, 160°C and 200°C to study the influence of temperature on OA capped PbS nanoparticles. Powder X-ray diffraction patterns confirms that the as-prepared PbS are cubic rock salt crystalline phase of PbS. High resolution transmission electron microscopy (HRTEM) micrographs crystallite average size of 2.64 nm for particles prepared at 120°C, 4.12 nm for particles prepared at 160°C, and 1.93 nm for particles prepared at 200°C from [Pb(EtPhdtc)2]. The average crystallite sizes of PbS nanoparticles obtained from [Pb(BzyMedtc)2] are 6.61 nm at 120°C, 13.88 nm at 160°C, and 10.82 nm at 200°C. The as-prepared PbS nanocrystals were used as photocatalyst for the degradation of methylene blue with the highest degradation efficiency of 73.89% recorded for OAPbS1a. [ABSTRACT FROM AUTHOR]

In this work, Cu-Ag core-shell nanoparticles were synthesized via a chemical reduction method. Subsequently, Cu-Ag core-shell nanoparticles were dispersed into polyvinyl alcohol (PVA) and films were grown by solution casting technique. High resolution transmission electron microscopy (HRTEM) was utilized to confirm the synthesis of Cu-Ag core-shell nanoparticles. Optical properties of fabricated films were investigated using UV-Visible absorption spectroscopy. Analysis of absorption data indicated that the band gap of PVA decreases with increasing Cu-Ag core-shell nanoparticles concentration while urbach's energy increases. The possible reasons for the observed changes in optical parameters of PVA with the incorporation of Cu-Ag core-shell nanoparticles have been discussed in detail. [ABSTRACT FROM AUTHOR]

Objective: In this study, we compared in vitro and in vivo bioactivity of nitrogen-doped multi-walled carbon nanotubes (NDMWCNT) to MWCNT to test the hypothesis that nitrogen doping would alter bioactivity. Materials and Methods: High-resolution transmission electron microscopy (TEM) confirmed the multilayer structure of MWCNT with an average layer distance of 0.36 nm, which was not altered by nitrogen doping: the nanomaterials had similar widths and lengths. In vitro studies with THP-1 cells and alveolar macrophages from C57BL/6 mice demonstrated that NDMWCNT were less cytotoxic and stimulated less IL-1β release compared to MWCNT. For in vivo studies, male C57BL/6J mice received a single dose of dispersion medium (DM), 2.5, 10 or 40 µg/mouse of NDMWCNT, or 40 µg/mouse of MWCNT by oropharyngeal aspiration. Animals were euthanized between 1 and 7 days post-exposure for whole lung lavage (WLL) studies. Results and Discussion: NDMWCNT caused time- and dose-dependent pulmonary inflammation. However, it was less than that caused by MWCNT. Activation of the NLRP3 inflammasome was assessed in particle-exposed mice by determining cytokine production in WLL fluid at 1 day post-exposure. Compared to DM-exposed mice, IL-1β and IL-18 were significantly increased in MWCNT- and NDMWCNT-exposed mice, but the increase caused by NDMWCNT was less than MWCNT. At 56 days post-exposure, histopathology determined lung fibrosis in MWCNT-exposed mice was greater than NDMWCNT-exposed mice. Conclusions: These data indicate nitrogen doping of MWCNT decreases their bioactivity, as reflected with lower in vitro and in vivo toxicity inflammation and lung disease. The lower activation of the NLRP3 inflammasome may be responsible. Abbreviations: NDMWCNT: nitrogen-doped multi-walled carbon nanotubes; MWCNT: multi-walled carbon nanotubes; TEM: transmission electron microscopy; HRTEM: high resolution transmission electron microscopy; IL-1ß: interleukin-1ß; DM: dispersion medium; WLL: whole lung lavage; IL-18: interleukin-18; GSD: geometric standard deviation; XPS: X-ray photoelectron spectroscopy; SEM: standard error of the mean; PMA: phorbol 12-myristate 13-acetate; LPS: lipopolysacharride; LDH: lactate dehydrogenase; AM: alveolar macrophage; PMN: polymorphonuclear leukocyte [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) has been synthesized by modified Hummers' method and characterized by Fourier transform infrared spectroscopy, ultraviolet visible spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction technique and Raman spectroscopy. GO characterized using Fourier transform infrared spectra shows that the graphite powder is strongly oxidized by resilient oxidants and the oxygen atoms are present in form of functional groups such as COOH, O–H, C–O–C, and C = O, bonds. GO pellets were prepared to study its dielectric properties as a function of frequency. Dielectric permittivity and electrical conductivity of GO strongly depends upon the extent of temperature. [ABSTRACT FROM AUTHOR]

In this work, we have studied the microscopic, ferroelectric, magnetic and microstructural characteristics of cobalt ferrite/barium titanate core–shell magnetoelectric nanocomposites. Magnetoelectric nanocomposites with 22 nm mean particle size were successfully obtained and observed by High Resolution Transmission Electron Microscopy and Scanning Transmission Electron Microscopy. Ferroelectric and magnetic properties were studied and confirmed by Scanning Probe Microscopy. Ferroelectric nanoregions were observed at the nanocomposites shell and magnetic nanoregions were highlighted in the nanocomposites core. Thus, magnetoelectric nanocomposites suitable for use in multifunctional biological/biomedical/bioengineering applications, as magnetic field nanosensors and other multifunctional applications were obtained. [ABSTRACT FROM AUTHOR]

Carbon particles (Soot) have been the one of primary pollutants inevitably with the combustion of fossil fuels. A better understanding on incipient soot was useful to build the models of soot formation and even control soot emissions. The present work focuses on the nanostructure and oxidation reactivity of nascent carbon particles (soot) formed from 2,5-dimethylfuran (DMF)/n-heptane non-swirling and swirling inverse diffusion flames (IDFs). The nascent soot samples were derived from three different fuels: 100% n-heptane, 50% n-heptane/50% DMF and 100% DMF. In addition, the effects of swirling combustion and collection time on characteristics of nascent soot were investigated in detail using the high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Results demonstrated that nascent soot from pure n-heptane flames presented the film-like morphology and nanostructure of amorphous nature, while the nearly primary particles with more well-organized nanostructure were found in pure DMF soot. Swirling combustion increased the entire flame front areas and diameters due to the existence of tangential velocity at the outlet of burner. Moreover, swirling combustion could enhance the mixability of the oxidizer stream and fuel stream, leading to more young soot within the fuel stream being oxidized in the inception stage. However, the collection time on soot characteristics exhibited quite negligible impacts in comparison to the swirling effects. [ABSTRACT FROM AUTHOR]

The poorly known dinoflagellate Sinophysis canaliculata, which was originally described from the Indian Ocean, was abundant in a collection from 2015 from Rapa Iti, a small, remote island of French Polynesia. Since the taxonomic description of this species was incomplete, a detailed morphological study was carried out. The theca was studied with epifluorescence microscopy using Solophenyl Flavine 7GFE500, a fluorescent dye specific to cellulose. This fluorophore was used successfully for the first time with a thecate dinoflagellate. It has the advantage of using blue excitation light and avoids the fading of fluorescence encountered with other dyes with long excitation time. Using this technique and high-resolution field emission scanning electron microscopy, the thecal plate pattern was clarified, and the epitheca had six major plates, 4E and 2A. A conspicuous apical pore was present on the left side of the epitheca. A smaller pore was located on the ventral left side of the apical pore. The apical plates A1 and A2 formed prominent projections which encircled and partly covered the pores. This thecal pattern agreed with the recent emended description of the genus. Two additional platelets, visible only from inside the cell, were possibly present in contact with the pores. In addition, the 'canal' cut on the left hypothecal plate H2 had a slit at its base. Seen from the inside, the slit was actually a sieve-like area comprising several small pores with a diameter of 80-100 nm. We hypothesise that this novel structure functions in the extrusion of mucus threads. [ABSTRACT FROM AUTHOR]

High-resolution electron microscopy (HREM) at the atomic scale has been applied to study the edge dislocation redistribution between interfaces in Ge/Ge0.5Si0.5/Si(0 0 1) heterostructures. Our results provide a direct explanation that plastic relaxation of the GeSi buffer layer proceeds owing to motion of Lomer-type dislocation complexes consisting of a pair of complementary 60° dislocations with the ends of the {1 1 1} extra planes being located at a distance of ~2–12 interplanar spacings from each other. It is demonstrated that edge dislocations belonging to the upper and lower interfaces become arranged one under the other and dislocation walls are formed. The distributions of tension and compression in the [0 0 1] direction between two edge dislocations, obtained by processing the HREM image, testify to superposition of strain fields. [ABSTRACT FROM AUTHOR]

George was a towering presence in the light metal corrosion and protection field over his long career almost entirely based at UMIST and then at the University of Manchester. Professor George Thompson, OBE, DSc, FREng (1946-2020) Graph It is with deep sadness that we share the news that our dear friend and colleague, Professor George Edward Thompson, passed away after a long illness on the 9th December 2020. George wasn't what you'd call self-effacing, but he had every reason not to be as for several decades he was considered by many to be the "go to" in international academic circles for all things related to aluminium oxidation and corrosion control, particularly for the fundamentals of aluminium oxide growth mechanisms and the use of advanced characterisation techniques. [Extracted from the article]

The medfly (Ceratitis capitataWiedemann, 1824) is a widespread pest for horticulture, mainly targeting fruits of pomaceous and citrus cultivars. Scanty data is available about its chemosensory responses to contact salty, sweet, sour and bitter stimuli. High Resolution Scanning Electron Microscopy (HRSEM) and Transmission Electron Microscopy (TEM) observations indicate the presence of six pairs of Long type and about 40 pairs of Intermediate type labellar chemosensilla, each containing four different neurons. Spike activity was electrophysiologically recorded from the labellar sensilla in response to sodium chloride (NaCl), fructose, acids (citric and malic) and bitter compounds (quinine, quercetin and 6-n-propyl-thiouracil (PROP)). By analysis of spike waveforms in the responses, four neurons were identified responding to different stimuli in both sensillum types ofC. capitata. The response specificity of three of these cells (named M1, M2 and S) was determined on the basis of their dose-response profiles. “M1” was specific to NaCl, “M2” to fructose. Both acids appeared to excite the “S” cell and to inhibit the “M1” cell. Citric acid also partly inhibited the response of the “M2” cell. No cell clearly responded to any of the bitter stimuli. [ABSTRACT FROM AUTHOR]

Nanorobotic techniques are well-known for characterization and processing of two-dimensional materials. However, until now, most of the proposed handling procedures required manual feedback. This article presents an automated handling approach of two-dimensional nanomaterials using a robotic setup inside a high-resolution scanning electron microscope. Applying image processing of the visual feedback provided by the electron microscope, a fully automated sequence is developed to align a robotic driven force sensor with sub-micrometer accuracy and to conduct nanoindentation measurements on a periodically perforated substrate. As an example, this automated sequence is utilized to examine the mechanical properties of a few-layer graphene membrane. The results of the mechanical characterization are compared to Raman spectroscopy data. The article discusses the advantages and restrictions of this technique and responds to further application scenarios. [ABSTRACT FROM AUTHOR]

The microstructure of interfacial defects in YBa2Cu3O7-δ/SrTiO3(0 0 1) heterostructures has been investigated by aberration-corrected ultrahigh-resolution electron microscopy. We determine thatc-axis-oriented YBa2Cu3O7-δthin films epitaxially grow on SrTiO3(0 0 1) with two types of interface structure. The coalescence of nucleation sites with different types of interface structure leads to the formation of antiphase domain boundaries in YBa2Cu3O7-δthin films, which terminate at planar faults with different configurations near the interface. Stand-off misfit dislocations are observed and the dislocation core structure is explored. Based on the interface structure and interfacial defects, the initial growth mode of YBa2Cu3O7-δthin films on SrTiO3(0 0 1) is discussed. [ABSTRACT FROM AUTHOR]

Twin boundary (TB) structure and interface defects in atwin in deformed polycrystalline cobalt were studied by using high-resolution electron microscopy (HREM). TheTB tends to be flat and a mirror plane. Two interface defects with Burgers vectorsb−2/−2andb17/17were found. The core structures of the observed interface defects were relatively compact. [ABSTRACT FROM AUTHOR]

Structural features of layered boride YbAlB4single crystals with YCrB4-type (α-type) and ThMoB4-type (β-type) phases derived from a hexagonal AlB2-type structure were investigated by electron diffraction, high-resolution electron microscopy and X-ray diffraction. X-ray diffraction experiments indicate the existence of some structural motifs. High-resolution images clearly show that the structural motifs build the intergrown lamellar structures in the matrix. The lamellar structures can be characterized by a coherent tiling of deformed Yb hexagons, which are a common structure unit in the α- and β-type structures. The characteristic intergrown nanostructure is similar to that observed in the β-type TmAlB4polycrystalline sample. [ABSTRACT FROM AUTHOR]

Co based oxide dispersion strengthening (ODS) alloys strengthened by oxide nanoparticles and γ′ precipitates are promising high temperature structural materials. Phase evolution, thermal stability and interfacial structure of the oxides were characterised, and the formation mechanism of the complex oxides was clarified. Co based ODS alloys exhibit inhomogeneous dispersion of the oxides due to the presence of relatively large Y-Al-O and fine Y-Hf-O complex oxides. Oxide particle size was controlled by the relative amount of Y-Al-O and Y-Hf-O oxides. The addition of Hf inhibits the formation of Y-Al-O oxides, resulting in the refinement of the oxides. The coherency of the matrix/oxide interface is size dependent. Large Y-Al-O complex oxides are incoherent with the matrix, while small Y-Hf-O nanoparticles tend to be partially coherent with the matrix. The extremely fine Y2Hf2O7 complex oxides demonstrate excellent thermal stability during heat treatment. Based on the observations of partially crystallised nanoparticles and the oxides with core/shell structure, a three-stage mechanism was used to elucidate the formation mechanism of the complex oxides. [ABSTRACT FROM AUTHOR]

High-resolution transmission electron microscopy was used to analyze basal-plane dislocations, which display very characteristic contrasts in grazing incidence monochromatic X-ray topographic images, on the Si-face of 4H–SiC. Grazing incidence monochromatic synchrotron X-ray topography, which is a lattice defect observational technique, has been used in power devices made from 4H–SiC. This technique is useful in analyzing lattice defects near the surface but without the contrast of high-density lattice defects inside the wafer. Basal-plane dislocations exhibit several distinct types of contrast: dark, bright, asymmetric dark/bright and intermediate contrast. Dark and bright contrast areas have been reported to be the edge dislocation regions of basal-plane dislocations. Nevertheless, it remains unclear whether the dark contrast regions are edge dislocations with extra half-planes on the surface side, i.e. Si-core edge dislocations, or those with extra half planes on the deeper crystal side, namely C-core edge dislocations on the Si-face. In this paper, basal-plane dislocations with dark contrast edge dislocations in grazing incidence X-ray topographic images around the (0001) surface were observed via high-resolution transmission electron microscopy, and it was determined that the extra half planes are located on the deeper side against the Si-face. This indicates that the dark contrast edge dislocations are those with a C-core structure on the Si-face. This conclusion is important in establishing the analytical procedure for dislocation contrast in grazing incidence monochromatic X-ray topography on Si face images. [ABSTRACT FROM AUTHOR]

We report on the effect of cooling rate on the size-dependent atomic ordering of CoPt nanoparticles using aberration corrected high-resolution transmission electron microscopy. It was found that cooling rate plays a crucial role in promoting atomic ordering during the cooling process after annealing. Nanoparticles of ≈3 nm in diameter show the A1-disordered phase after annealing at 873 K for 1 h followed by rapid cooling (110 K/min), while the L10-ordered phase is obtained when the cooling rate is slow (1.5 K/min). The disordered phase is also obtained by rapid cooling after annealing at 973 K for 1 h. These results unambiguously indicate that the order–disorder transformation temperature is reduced to a temperature at least lower than 873 K for CoPt nanoparticles smaller than 3 nm in diameter. The slow cooling process promotes the atomic ordering, which resulted in an enhancement of magnetic coercivity as high as 2200 Oe. This study demonstrates that hard magnetic properties of the CoPt nanoparticles can be improved by controlling the cooling rate after heat treatments. [ABSTRACT FROM AUTHOR]

Single crystals, with a typical size of several millimetres, of a decagonal phase with 1.6 nm periodicity in the Al-Ni-Ru system were grown successfully by the solution-growth method. The conditions for crystal growth were that the initial composition was Al80Ni16Ru4, the taking-out temperature 900-930°C and the cooling rate 2°C h-1. The lattice parameters were a = 0.2764(2) and c = 1.6523(5) nm, and the composition was in a small range around Al75.2Ni14.6Ru10.2. Single crystals of the orthorhombic Al13(Ni, Ru)4 phase and the monoclinic Al13(Ni, Ru)4 phase located at the high-Ni end also formed under slightly different conditions. [ABSTRACT FROM AUTHOR]

We found 32 variations of dot tiling (DT) reported previously [J. Alloy. Comp. 342 (2002) p.206], which is similar to a tiling consisting of pentagon, hexagons, nonagon and decagons (PHND) [Phil. Mag. A l76 (1997) p.85] employed in the structure analysis of decagonal quasicrystals. They are its superstructures, with a five times larger unit cell in four-dimensional space. These tilings are built up by adding one dot in each fat rhombus in the rhombic Penrose tiling. Eight tilings among 32 DTs do not break the local symmetries of the eight types of vertices in the rhombic Penrose tiling. The eight tilings and their occupation domains are shown. [ABSTRACT FROM AUTHOR]

Automated methods for capturing geometric and spectral properties of individual tree crowns are becoming increasingly viable options for use in natural resource planning. Crown isolation techniques are needed that are capable of adapting to the changing availability and resolutions of remotely sensed data. Data integration, or the fusion of two distinct data entities, offers a methodological framework that can compensate for the shortcomings of individual datasets while enhancing their desirable features. This study sought to develop a method of data integration for high-resolution optical images of varying spatial and temporal resolutions to improve the automatic detection and delineation of individual tree crowns. A marker-controlled watershed segmentation (MCWS) algorithm was developed for a 30-cm-per-pixel-side airborne colour infrared (CIR) digital image of a leaf-on apple (Malus spp.) orchard. Three methods of obtaining the markers needed for the MCWS algorithm were tested: (1) manual marker selection, (2) template/correlation selection using the 30-cm CIR image, and (3) template/correlation selection using a 15-cm-per-pixel-side true (TRU) colour leaf-off aerial image. The effectiveness of integrating marker data of different temporal and spatial resolutions with the segmentation process of the CIR image scene was tested. A comparison of crown isolation results using markers derived within the segmented 30-cm CIR digital imagery with results from markers derived from the 15-cm TRU image scene indicated greater accuracies to detect and isolate tree crowns with data integration. [ABSTRACT FROM AUTHOR]

Transmission electron microscopy (TEM) of polymers involves the problem definition and methodologies associated with the microscopy of both inorganic and biological materials but cannot be categorized within either of these fields alone. On the one hand, like other synthetic materials, polymers offer the ability to control properties through synthesis and processing, and TEM is a powerful method with which to provide information within the synthesis-structure-property paradigm of materials science and engineering. The well-established techniques of bright/dark-field imaging, electron diffraction, high-resolution imaging, and analytical microscopies are thus all used to study polymers. On the other hand, the electron-specimen interactions are more like those in biological systems. Synthetic polymers and biological materials consist largely of light elements whose elastic interactions with energetic electrons are relatively weak. Generating image contrast can thus be a challenge in polymer TEM. The inelastic electron/soft material interactions are, however, relatively strong. These provide for powerful spectroscopies but also lead to radiation damage. The constraints that damage puts on imaging are far more stringent in polymers than in inorganic systems. This review highlights ongoing advances in contrast generation exploiting both elastic and inelastic electron-polymer interactions and outlines the salient issues determining the achievable spatial resolution in radiation-sensitive materials. [ABSTRACT FROM AUTHOR]

Traditional spectral-based methods of extracting urban land cover and land use information from remote sensing imagery have proven to be unsuitable for high spatial resolution images. Texture has been widely investigated as a supplement to spectral data for the analysis of complex urban scenes. This research evaluates the grey level co-occurrence matrix (GLCM) texture analysis technique and the maximum likelihood classification approach for the extraction of texture features to be combined with spectral data, as a method for obtaining more accurate urban land cover and land use information from high spatial resolution images. Classifications were performed on IKONOS imagery using three datasets: a spatial dataset consisting of three texture images (mean, homogeneity and dissimilarity), a spectral dataset consisting of four spectral images (red, green, blue and NIR) and a combination dataset (spatial and spectral). Results show that the combination dataset produced the highest overall classification accuracy of 86.1%, an improvement of 7.2% over the spectral dataset. [ABSTRACT FROM AUTHOR]

The objective of the present study was to investigate the crystallography and morphology of TiC particles in a titanium containing high strength low alloy (HSLA) steel that form during isothermal transformation at a temperature in the (α+γ) phase field. The orientation relationships (ORs) were identified from selected area diffraction patterns (SADPs) and from moire fringes in high resolution transmission electron microscopy (HRTEM) lattice images. It was found that in the initial stages of the isothermal transformation, fine plate-like TiC particles develop and that these exhibit the Baker-Nutting (BN) OR with respect to the ferrite matrix. In the later stages of the transformation, however, coarser plate-like carbides are observed, and these adopt approximately the Nishiyama-Wassermann (NW) OR with respect to the ferrite matrix. The evidence indicates that OR transition is brought about simply by aging for a longer time at the transformation temperature, and also manifests a rotation of the precipitate during coarsening. [ABSTRACT FROM AUTHOR]

Electrospinning was employed to fabricate 3-D fiber networks from a recombinant amphiphilic elastin-mimetic tri-block protein polymer and the effects of moderate thermal conditioning (60°C, 4 h) on network mechanical responses investigated. Significantly, while cryo-high resolution scanning electron microscopy (cryo-HRSEM) revealed that the macroscopic and microscopic morphology of the network structure was unchanged, solid-state 1H-NMR spectroscopy demonstrated enhanced interphase mixing of hydrophobic and hydrophilic blocks. Significantly, thermal annealing triggered permanent changes in network swelling behavior (28.75 ± 2.80 non-annealed vs. 13.55 ± 1.39 annealed; P < 0.05) and uniaxial mechanical responses, including Young's modulus (0.170 ± 0.010 MPa non-annealed vs. 0.366 ± 0.05 MPa annealed; P < 0.05) and ultimate tensile strength (0.079 ± 0.008 MPa vs. 0.119 ± 0.015 MPa; P < 0.05). To our knowledge, these investigations are the first to note that mechanical responses of protein polymers can be permanently altered through a temperature-induced change in microphase mixing. [ABSTRACT FROM AUTHOR]

Magnesium matrix composites reinforced with nano-sized SiC particles (n-SiCp/AZ91D) were fabricated by high intensity ultrasonic assisted casting. The microstructure of the nanocomposites was investigated by optical microscopy, scanning electronic microscopy (SEM), high resolution transmission electronic microscopy (HRTEM) and Energy Dispersive Spectroscopy (EDS) methods. The results showed that the dispersion and distribution of n-SiCp in magnesium alloy melts were significantly improved by ultrasonic processing. Compared to the unreinforced AZ91D matrix, mechanical properties of the nanocomposites including tensile and yield strengths were remarkably improved and the yield strength increased by 117% after gravity permanent mould casting. [ABSTRACT FROM AUTHOR]

The multi-walled carbon nanotubes were synthesized on Fe-Ni bimetallic catalysts supported by MgO using thermal chemical vapor deposition. A comparative study on the effect of nitric acid molarity and time duration of acid treatment on purification of multi-walled nanotubes was done. The studies revealed that for finding a suitable condition for purification of multi-walled carbon nanotubes, it is necessary to determine suitable molarity of acid and immersion time of the carbon nanotubes. It was found that 5 M of boiling nitric acid at 3 h leads to the highest removal of the impurities with the least destructive effect. Various analytical techniques such as: scanning electron microscopy (SEM), high resolution transition electron microscopy (HRTEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and Raman spectroscopy techniques were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. [ABSTRACT FROM AUTHOR]

La0.61Li0.17TiO3 microstructures have been studied by high resolution electron microscopy. A local lattice distortion occurs in the vicinity of the domain boundary region due to the twin with an angle of 89°. The average domain size of La0.61Li0.17TiO3 is greater than 20 nm. The domain size and structures of La0.61Li0.17TiO3 differ greatly from those of La-poor compounds, such as La0.55Li0.35TiO3. At a nanoscopic level, microdomains of 20-100 nm in size construct a two-dimensional structure in La-rich compounds, while microdomains of 5-10 nm in size construct a three-dimensional structure in La-poor compounds. In addition, the Li-ion conduction mechanisms for La-rich and La-poor compounds are two- and three-dimensional, respectively. [ABSTRACT FROM AUTHOR]

Parallel stacking faults on (010) planes are frequently observed in hot-pressed Y2Si2O7. A combination of conventional dark-field imaging and high-resolution transmission electron microscopy was used to investigate the structure of these faults. It was found that they consisted of the repeat of one layer of the two-layer γ-Y2Si2O7 structure with an associated in-plane rigid body displacement. The resulting structure was confirmed by image simulation of high-resolution images from two perpendicular projections. A model for the formation of the stacking faults is proposed as a consequence of a transformation from β-Y2Si2O7 to γ-Y2Si2O7 in the hot pressing. [ABSTRACT FROM AUTHOR]

Two types of twin boundaries in superconductor Y0.6Na0.4Ba2Cu2.7Zn0.3O7-δ, the cation-centered and oxygen-centered types, and the associated twinning dislocation have been studied by high-resolution electron microscopy. The structure map projected in the [001] direction was obtained from a single image by means of the image deconvolution technique. In this map, all columns of metallic atoms appear as individual black dots, and hence the two types of twin boundaries are distinguished from each other at atomic level. It is seen that the twinning dislocation occurs when the two types of twin boundaries meet each other. The structure model of the twinning dislocation together with the two types of twin boundaries has been derived straightforwardly based on the positions of black dots seen in the deconvoluted image. [ABSTRACT FROM AUTHOR]

Highly supersaturated solid solutions of nitrogen in ferrite (bcc) were produced by ball milling of various powder mixtures of α-iron and ε-Fe3N1.08. The microstructure and the crystal structure of the product phases were examined as a function of nitrogen content using X-ray powder diffraction, high-resolution electron microscopy and Mossbauer spectroscopy. It was found that the grain size decreases with increasing nitrogen content. Unexpected shifts of the reflections in the X-ray powder diffraction patterns of the supersaturated N-ferrites, depending on the hkl values of the reflections and nitrogen content, were observed. These shifts cannot be explained by tetragonal distortion of the bcc unit cell, but they are in accordance with the occurrence of a certain type of stacking faults on bcc {211} planes. This result, together with the observation of some isolated fcc crystals (by high-resolution electron microscopy) and a drop in microstrain for high nitrogen contents, demonstrates that unconventional deformation mechanisms are operative in these materials below a certain grain size, leading to a breakdown of the classical Hall-Petch relation for mechanical strengthening. [ABSTRACT FROM AUTHOR]

Image shadow segmentation has become a major issue in satellite remote sensing because of the recent commercial availability of high-resolution images. Detecting shadows is important for successfully carrying out applications such as change detection, land monitoring, object recognition, scene reconstruction, colour correction, etc. This paper presents a simple and effective procedure to segment shadow regions on high-resolution colour satellite images. The method applies a region growing process on a specific band (namely, the c 3 component of the c 1 c 2 c 3 colour space). To gain in robustness and precision, the region expansion also imposes a restriction on the saturation and intensity values of the shadow pixels, as well as on their edge gradients. The proposed method has been successfully tested on QuickBird images acquired under different lighting conditions and covering both urban and rural areas. [ABSTRACT FROM AUTHOR]