Optical properties of gold island films—a spectroscopic ellipsometry study

Metal island films of noble metals are obtained by deposition on glass substrates during the first stage of evaporation process when supported metal nanoparticles are formed. These films show unique optical properties, owing to the localized surface plasmon resonance of free electrons in metal nanoparticles. In the present work we study the optical properties of gold metal island films deposited on glass substrates with different mass thicknesses at different substrate temperatures. The optical characterization is performed by spectroscopic ellipsometry at different angles of incidence and transmittance measurements at normal incidence in the same point of the sample. Fitting of the ellipsometric data allows determining the effective optical constants and thickness of the island film. A multiple oscillator approach was used to successfully represent the dispersion of the effective optical constants of the films.     

Changes of properties of cured and uncured disiloxane bisbenzocyclobutene thin films under irradiation

The effects induced by α-particles and laser beam irradiation in air atmosphere in uncured and cured bisbenzocyclobutene (BCB) 2 μm thick films, spin-coated on glass/ITO surface have been investigated. α-Particle irradiation was done by means of a thin film ²⁴¹Am source (E_α = 5.486 MeV), up to the total fluence of about 5 × 10¹⁰ particles/cm². Laser irradiation was performed by a Nd³⁺:YAG (λ = 1.06 μm) laser in the free generation and the Q-switch regime, using both focused and unfocused beams. Irradiation induced changes were investigated using Light and Atomic Force Microscopy (AFM), infrared (IR), Ultraviolet/visible (UV/vis) and Raman spectroscopy by inspecting several uncured and cured BCB films before and after irradiation. It has been found that both types of irradiation under investigated conditions have produced a novel phase in the material, which is not present either in the uncured or the cured BCB films. Possible implications of the observed effects on curing and degradation of BCB films have been discussed.     

Kinetics and thermochemistry of the boron-fuelled pyrotechnic compositions BLC 190 and BLC 181 at their ignition temperatures

Around 700 K, the pyrotechnic compositions BLC 190 (boron : red lead, 10 : 90) and BLC 181 (boron : red lead : chromic oxide, 10 : 80 : 10) undergo exothermic thermal decomposition reactions which follow first order kinetics. The reaction of BLC 190 is faster than that of BLC 181 but the energies of activation, ca. 446 kJ mol^?1, and the heat output per unit mass of oxidant, Pb₃0₄’ ca. 1000 J g^?1, are very similar suggesting that the reactions of each of these formulations follow identical pathways. The product of the reaction from BLC 190 has been identified as lead tetraborate or a closely related compound.     

Blockchain-based solutions for security,privacy, and trust management in vehicular networks: a survey

The Journal of Supercomputing - Vehicular networks are considered as one of the most pertinent research topics in intelligent transportation systems and anchors for future smart city environment...     

Identification of metaphors for virtual environment training systems

The objective of this effort was to develop potential metaphors for assisting wayfinding and navigation in current virtual environment (VE) training systems. Although VE purports a number of advantages over traditional, full-scale simulator training devices (deployability, footprint, cost, maintainability, scalability, networking), little design guidance exists beyond individual instantiations with specific platforms. A review of metaphors commonly incorporated into human-computer interactive systems indicated that existing metaphors have largely been used as orientation aids, mainly in the form of guided navigational assistance, with some position guidance. Advanced metaphor design concepts were identified that would not only provide trainees with a useful orienting framework but also enhance visual access and help differentiate an environment. The effectiveness of these concepts to aid navigation and wayfinding in VEs must be empirically validated.     

Recovery from equipment failures in ATC: Determination of contextual factors

Human reliability assessment (HRA) currently uses various approaches to determine and quantify human error. These approaches are increasingly being employed in various safety-critical domains, such as air traffic management and its ground component air traffic control. HRA research over the years has shown the important role of the context in which human errors take place. Recent techniques now put more emphasis on the definition of key contextual factors and their impact on the reliability of human performance. This paper presents a review of the current understanding of contextual factors in various industries. It uses this together with results from controller interviews to identify the contextual factors relevant to controller recovery from equipment failures in air traffic control. These factors should be used in conjunction with an appropriate method to analyse the performance of a controller during the process of recovery from failures.     

Optical and structural characterization of silver islands films on glass substrates

Metal island films (MIFs) of Ag on glass substrates were fabricated by the e-beam evaporation technique. The dependence of the surface plasmon (SP) absorption properties on the deposition mass thickness and substrate temperature was quantified. The structural and optical characterization of the MIFs, obtained using spectrometry, grazing-incidence small-angle X-ray scattering (GISAXS) and atomic force microscopy (AFM) evidences the evolution of SP characteristics depending on the fabrication parameters: the red shift of the absorption peaks with the increase of deposition thickness accompanied by peak widening and the blue-shift of peaks with the increase of deposition temperature followed by the peak narrowing. These findings were explained by the differences in the concentration, shape and size of the obtained silver islands.     

Toxicity assessment of heavy metal mixtures by Lemna minor L

The discharge of untreated electroplating wastewaters directly into the environment is a certain source of heavy metals in surface waters. Even though heavy metal discharge is regulated by environmental laws many small-scale electroplating facilities do not apply adequate protective measures. Electroplating wastewaters contain large amounts of various heavy metals (the composition depending on the facility) and the pH value often bellow 2. Such pollution diminishes the biodiversity of aquatic ecosystems and also endangers human health. The aim of our study was to observe/measure the toxic effects induced by a mixture of seven heavy metals on a bioindicator species Lemna minor L. Since artificial laboratory metal mixtures cannot entirely predict behaviour of metal mixtures nor provide us with informations relating to the specific conditions in the realistic environment we have used an actual electroplating wastewater sample discharged from a small electroplating facility. In order to obtain three more samples with the same composition of heavy metals but at different concentrations, the original electroplating wastewater sample has undergone a purification process. The purification process used was developed by Orescanin et al. [Orescanin V, Mikeli? L, Luli? S, Nad K, Rubci? M, Pavlovi? G. Purification of electroplating wastewaters utilizing waste by-product ferrous sulphate and wood fly ash. J Environ Sci Health A 2004; 39 (9): 2437-2446.] in order to remove the heavy metals and adjust the pH value to acceptable values for discharge into the environment. Studies involving plants and multielemental waters are very rare because of the difficulty in explaining interactions of the combined toxicities. Regardless of the complexity in interpretation, Lemna bioassay can be efficiently used to assess combined effects of multimetal samples. Such realistic samples should not be avoided because they can provide us with a wide range of information which can help explain many different interactions of metals on plant growth and metabolism. In this study we have primarily evaluated classical toxicity endpoints (relative growth rate, Nfronds/Ncolonies ratio, dry to fresh weight ratio and frond area) and measured guaiacol peroxidase (GPX) activity as early indicator of oxidative stress. Also, we have measured metal accumulation in plants treated with waste ash water sample with EDXRF analysis and have used toxic unit (TU) approach to predict which metal will contribute the most to the general toxicity of the tested samples.