Wurtzite GaN films irradiated at room temperature with 308 MeV 129Xe35+ or 230 MeV 208Pb27+ ions have been studied by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The three-dimensional AFM images showed that swellings of the GaN films were caused by the ion irradiations at very low fluences. In comparison with the Xe ions, the Pb ions led to a much more pronounced swelling. The XPS results indicated that after the Xe and Pb irradiations, the contents of Ga and N dangling bonds in the GaN increased, and the contents of Ga-O and N-O bonds in the surface layer also increased. In the case of the Pb irradiation, a peak associated with the defect of interstitial N was detected in the N 1s core-level spectrum, implying the formation of N2 bubbles close to the GaN surface. However, no homonuclear Ga-Ga bond was found according to the related Ga 3d spectrum. The dramatic experimental results are discussed and the distinct difference of irradiation damages in GaN induced individually by the Xe and Pb ions is analyzed.

De Haas-van Alphen oscillations of the organic metal θ-(ET)4ZnBr4(C6H4Cl2) are studied in pulsed magnetic fields up to 81 T. The long decay time of the pulse allows determining reliable field-dependent amplitudes of Fourier components with frequencies up to several kiloteslas. The Fourier spectrum is in agreement with the model of a linear chain of coupled orbits. In this model, all the observed frequencies are linear combinations of the frequency linked to the basic orbit α and to the magnetic-breakdown orbit β.

AlN films of thicknesses 670–780 nm were deposited on (1 1 1) silicon wafer, (0 0·1) sapphire, float glass and fused silica substrates by reactive mid-frequency (41 kHz) ac sputtering of dual hollow Al targets in a mixture of Ar and N2 gases. Nanostructured films of hexagonal wurtizite phase of AlN were prepared and characterized by UV-visible spectroscopy and X-ray diffraction. The novel geometry of dual target inverted cylindrical magnetrons produces very dense plasma and ion bombardment of the growing film, and facilitates the formation of highly crystalline AlN coatings without any deliberate substrate heating. Substrates showed significant influence on the crystal structure of AlN films; sapphire forms hexagonal AlN phase with very strong texturing toward (0 0·2) crystallographic orientation, silicon wafer grows small amount of metastable high-pressure cubic phase of AlN along with the predominant, thermodynamically stable hexagonal phase while the amorphous glass substrates form hexagonal AlN phase with a random orientation of the crystallites.

Pure iron nanoparticles (NPs) are fabricated using a simple and low-cost electric arc-discharge method in ethylene glycol (EG). The effect of different arc discharge currents (10, 20 and 30 A) on the size and optical absorption of the NPs is studied. Dynamic light scattering (DLS) and UV-visible spectroscopy data indicate that at the arc current of 10 A, the size of the particles is about 103 nm, and it can raise the arc current leading to larger NPs. UV-visible spectroscopy data show that the solvent gets more and more transparent with time, an effect which, sonication, proves that is related to agglomeration of the NPs. The evidence of pure Fe NPs is investigated by means of X-ray diffraction (XRD) measurement the average size of which is about 14 nm using Scherrer’s relation. Magnetization measurements of the samples are carried out by alternating gradient force magnetometer (AGFM). These results have shown that the arc discharge method is an effective method for preparing magnetic fluids in one step and EG is the effective medium for caring Fe NPs against oxidation. Therefore, the method can pave the way for the synthesis of other NPs such as Fe, Fe-Co, Fe-Pt and iron oxide.

We propose a simple method to design multichannel electron wave filters based on graphene superlattices with one-dimensional periodic potentials, which can choose not only the peak energy of each channel but also the bandwidth independently. This method is described by two samples for the design of two-channel, three-channel filters. Additional defects are introduced symmetrically into the superlattices, then modes are generated, which overlap with the channels that need to tune. These defects make the bandwidth of a certain channel increased without location shifted, while the other channels almost keep constant. The corresponding electronic devices may benefit from this method.

Gold nanoparticles have great potential toward optical investigations in biological tissues which include imaging applications as well as therapeutic applications. However, introduction of gold nanoparticles such as nanospheres into the tissue may alter the inherent physical properties of the embedding medium. Of note, the thermal diffusivity of the medium will be significantly altered imposing serious limitations to the efficacy of several imaging and therapeutic modalities. In this context, we report experimental investigations based on open photoacoustic cell configuration to evaluate the thermal diffusivity changes in polyvinyl alcohol (PVA) phantom tissue doped with gold nanospheres. The investigations performed demonstrate a non-destructive methodology for the measurement of thermal diffusivity and the experimental results show that the thermal diffusivity of the tissue will be significantly reduced when they are administered with plasmonic nanoparticles.

The minibands and minigaps in the transmission bands of one-dimensional photonic crystals have been studied through Bloch’s theorem, the tight-binding method and calculations based on the transfer matrix method. The minigap depths are dependent on the resonance intensity within the layers of one-dimensional photonic crystals and can be manipulated through the incidence angle. For a special structure and incidence angle, a polarization-independent flattop band can be achieved.

The effect of heat treatment on phase transformation and crystalline microstructure properties of ternary Al-Cu-Zn alloys made under nonequilibrium conditions was investigated by means of differential scanning calorimetry spectrometry (DSC), optical microscopy observations and X-ray diffraction (XRD) patterns analyses. A set of ternary Al-X wt.% Cu-X wt.%Zn alloys with nominal compositions X = 2, 8, 20 and 25 were rapidly solidified under vacuum by high-frequency magnetic induction melting process. It was found that DSC heating at temperatures below 500 °C leads to phase transformation with the development of new phases which were identified by XRD patterns analyses such as the presence at ambient temperature of the rhomboedric structure τ′-Al4Cu3Zn phase in equilibrium with the expected tetragonal θ-CuAl2 in Al matrix. Measured DSC crystallization enthalpies of occurring phase transformation were given. Optical microscopy observations reveal refined grains and homogeneous surface textures of the as-melted Al-Cu-Zn alloys.

This paper studies the usage of earthed atomizing corona discharge to dispose waste water from oil extraction. The I-V characteristic curves of earthed atomizing positive and negative corona discharge are compared to study the influence of water flux and inter-electrode distance (which refers to the distance between line electrode and plate electrodes) on discharge characteristics, and to measure the turbidity, pH, biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and the variation tendency of BOD5/COD in the process of dealing with waste water from oil extraction by earthed atomizing corona discharge. Ultimately, the mechanism of earthed atomizing corona discharge is analyzed. Research results indicate that when using earthed atomizing corona discharge to dispose of waste water from oil extraction, as the processing time grows there is a maximum value of turbidity, the pH level increases gradually then stabilizes, COD appears to descend, and BOD5 as well as BOD5/COD both have minimum values. When the processing time attains 300 min, waste water from oil extraction is suitable for biochemical treatment, foreshadowing that earthed atomizing corona discharge technology demonstrates energy conservation characteristic in improving the biodegradability of waste water from oil extraction and has a brilliant application prospect waiting ahead.

In this study, arrayed magnetic films were fabricated on the surface of 45# steel (magnetic). The magnetic field distribution of the micro-magnet arrayed surface was studied. Magnetically controlled suspension – ferrofluids was used as lubricant, which can be adsorbed by magnet. The tribological performance of the arrayed surface affected by the factors of micro-magnet, i.e., area ratio (r), thickness of each magnetic film (t) and magnetized or not, was evaluated using a pin-on-disk test rig. The results suggest that the specimen with 5% area ratio of arrayed magnet is the best of tried ones for low friction at the load-speed conditions. Compared with unmagnetized one, the arrayed surface after magnetizing mainly presents obvious anti-friction properties. The higher magnetic intensity of the surface is, the better anti-friction performance it shows at higher sliding speed condition (0.062–0.188 m/s).