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Abstract

Firing from gun armament generates a wide range of physico-chemical phenomena contributing to the degradation of barrel material, e.g. pressure, high temperature, chemically aggressive character of post-detonation gases and friction of a driving band. In this work the technique of thin foils was used in Transmission Electron Microscopy (TEM) to study the influence of physicochemical phenomena on the material microstructure of aircraft gun barrel. A mechanism and reason of premature wear-out of the barrel under consideration was also outlined by utilising light microscopy and hardness measurements.

membrane protein change combined with co-existing TEM-1 and SHV-1 beta-lactamases lead to false identification of ESBL-producing Klebsiella pneumoniae. J. Antimicrob. Chemother., 47, 755-761. Wu, Y. H., Chen, P. L., Hung, Y. P., Ko, W. C. (2014). Risk factors and clinical impact of levofloxacin or cefazolin nonsusceptibility or ESBL production among uropathogens in adults with community-onset urinary tract infections. J. Microbiol. Immunol. Infect., 47, 197-203.

Abstract

In this paper various types of films made of carbon nanotubes (CNTs) are presented. These films were prepared on different substrates (Al2O3, Si n-type) by the two-step method. The two-step method consists of physical vapor deposition step, followed by chemical vapor deposition step (PVD/CVD). Parameters of PVD process were the same for all initial films, while the duration times of the second step - the CVD process, were different (15, 30 min.). Prepared films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and field emission (FE) measurements. The I-E and F-N characteristics of electron emission were discussed in terms of various forms of CNT films. The value of threshold electric field ranged from few V/μm (for CNT dispersed rarely on the surface of the film deposited on Si) up to ~20 V/μm (for Al2O3 substrate).

. (2008). Properties of Pd nanocrystals prepared by PVD method. Vacuum 82, 372-376. DOI: 10.1016/j.vacuum.2007.08.003. 7. Czerwosz, E., Dłużewski, P., Kowalska, E., Kozłowski, M. & Rymarczyk, J. (2011). Properties of Pd-C films for hydrogen storage applications. Phys. Status Solidi C 8, 2527-2531. DOI: 10.1002/pssc.201000978. 8. Sobczak, K., Dłużewski, P., Witkowski, B.S., Dąbrowski, J., Kozłowski, M., Kowalska, E. & Czerwosz, E. (2012). TEM and CL investigation of Pd nanograins included in carbonaceous films. Solid State Phenomena 186, 177-181. DOI :10.4028/ www

Abstract

Colloidal silver nanoparticles were prepared by rapid green synthesis using different tannin sources as reducing agent viz. chestnut (CN), mangrove (MG) and quebracho (QB). The aqueous silver ions when exposed to CN, MG and QB tannins were reduced which resulted in formation of silver nanoparticles. The resultant silver nanoparticles were characterized using UV-Visible, X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and transmission electron microscopy (TEM) techniques. Furthermore, the possible mechanism of nanoparticles synthesis was also derived using FT-IR analysis. Spectroscopy analysis revealed that the synthesized nanoparticles were within 30 to 75 nm in size, while XRD results showed that nanoparticles formed were crystalline with face centered cubic geometry.

Abstract

Black silicon layers were formed on silicon substrate by the surface structure chemical transfer method and by anodic etching method. Properties of microstructure of formed layers were experimentally studied by the electron microscopy methods (TEM) and characterized by statistical, Fourier and multifractal methods. Theoretical structures with defined fractal properties and surface roughness were generated and their microstructure properties were evaluated. Obtained results were used for the explanation of the real structure development during the forming procedure. By using of this approach, we study the correlation of roughness and fractality with optical properties. Black silicon layers were also investigated by using of Raman scattering method. Optimized theoretical model describing the 1st order of black Si Raman scattering profile was constructed and used for evaluation of the biaxial tensile stress introduced during etching procedure.

Abstract

The growth of iron filled multiwalled carbon nanotubes (Fe-MWCNT) using chemical vapour deposition (CVD) has been widely studied. Considering the remarkable magnetic and structural properties of Fe-MWCNT, these materials have been applied in numerous areas. In particular their biomedical application has been explored, where Fe-MWCNT can be used in hyperthermia, acting as a local nano-heater at cellular level. Regarding this aim, the reproducible and highly purified ferromagnetically filled samples of carbon nanotubes are still required. There are several parameters during the synthesis process that influence the properties of the nanotubes. The most favourable temperature of the CNT growth is probably one of the most important issues and its optimisation is crucial. In the current study, the Fe-MWCNT were grown at different temperatures ranging from 650 °C to 1050 °C. Additionally, a comparison between two different CVD systems and two carbon sources are also here presented. The Fe-MWCNT were characterised using diverse techniques regarding the evaluation of their morphology, filling ratio, and purity. Observations showed a strong influence of the growth temperature on the morphology and properties of the Fe-MWCNT. The samples characterisation was performed using Raman spectroscopy, thermogravimetric analysis (TGA), X ray diffraction (XRD), and transmission electron microscopy analysis (TEM).

Influence of Nano Aluminium Powder Produced by Wire Explosion Process at Different Ambience on Hydrogen Generation

Nano-aluminium particles are produced through the wire explosion process in different gas medium. The particles produced by wire explosion process, in helium medium are of smaller size compared to argon/nitrogen medium. The nano aluminium powder on reaction with water forms oxides having bayerite and boehmite structure. It is observed that nano aluminium on reaction with KOH solution at room temperature it forms bayerite. The results of the study were confirmed through Wide Angle X-ray diffraction (WAXD) and by Transmission Electron Microscope (TEM) studies. The reaction of nano aluminium powder with KOH solution/water indicates that the rate of hydrogen generation is high when nano aluminium powder reacts with KOH solution than with water. The rate of hydrogen generation gets reduced drastically when the nano aluminium powder which is exposed to air medium for some period is used for reaction with KOH/water. It is also observed that the rate of hydrogen generation is high with nano size aluminium particles compared with ultrafine particles.

Abstract

Copper oxide and cobalt oxide (Co3O4, CuO) nanocrystals (NCs) have been successfully prepared using microwave irradiation. The obtained powders of the nanocrystals (NCs) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric (TGA) analysis and Fourier-transform infrared spectroscopy. The obtained results confirm the presence of both nanooxides which have been produced during chemical precipitation using microwave irradiation. TEM micrographs have shown that the obtained nanocrystals are characterized by high dispersion and narrow size distribution. The results of X-ray diffraction confirmed those obtained from the transmission electron microscope. Optical absorption analysis indicated the direct band gap for both kinds of the nanocrystals.

Abstract

Zn1-xNixO aerogel nanopowders with nickel concentration in the range of 0.05 ≤ x ≤ 0.25, were synthesized by the sol-gel processing technique and post-annealed in air at 500 °C. Structural, vibrational, thermal and magnetic properties of the as-prepared and annealed Zn1-xNixO powdered samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman scattering, thermal gravimetric analysis (TGA) and electron paramagnetic resonance (EPR) spectroscopy. In addition to the ZnNiO phase, XRD analysis revealed the formation of a secondary NiO phase when the Ni content was greater than or equal to 10 %. The TEM images confirm that the particle size is in the range of 20 nm to 40 nm, in accordance with XRD results, and the particles are well dispersed. Raman scattering measurements confirm the wurtzite structure of the synthesized Zn1-xNixO nanopowders and show that intrinsic host-lattice defects are activated when Ni2+ ions are substituted to the Zn sites. Room temperature ferromagnetic order was observed in all of the samples and was strongly dependent on the Ni content and thermal annealing. These results indicate that the observed room temperature ferromagnetism in ZnNiO may be attributed to the substitutional incorporation of Ni at Zn sites.