The influence of alizarin and fluorescein on the photoactivity of Ni,Pt and Ru-doped TiO2 layers

The doping with different metal ions and sensitization with organic compounds are two well known methods used to improve the photoactivity of TiO₂. In this respect, the metallic ions-doped TiO₂ samples were prepared by embedding Ni, Pt and Ru ions into TiO₂ crystalline network and then, each sample was sensitized with alizarin and fluorescein dyes. The qualitative evaluation of prepared TiO₂-based materials was made by: UV–vis spectroscopy, spectrofluorimetry, FT/IR spectroscopy and microscopy, X-ray diffraction and N₂ physisorption measurements. The optoelectronic properties investigated by UV–vis spectroscopy show that the optical response of Ni-doped TiO₂ layer shifts to visible. The X-ray spectra do not show peaks of nickel, platinum and ruthenium oxide crystals or pure metals. The FT/IR spectra proved the presence of dye molecules adsorbed on titania nanoparticles surface. These results demonstrated that the studied dopants and dyes have potential to promote modified TiO₂-based materials as good candidates to be used in photolectrocatalytic processes.     

Recombination luminescence and trap levels in undoped and Al-doped ZnO thin films on quartz and GaSe (0 0 0 1) substrates

Photoluminescence spectra of ZnO and ZnO:Al (1.00, 2.00 and 5.00 at.%) films on GaSe (0 0 0 1) lamellas and amorphous quartz substrates, obtained by annealing, at 700 K, of undoped and Al-doped metal films, are investigated. For all samples, the nonequilibrium charge carriers recombine by radiative band-to-band transitions with energy of 3.27 eV, via recombination levels created by the monoionized oxygen atoms, forming the impurity band laying in the region 2.00 ? 2.70 eV. Al doping induces an additional recombination level at 1.13 eV above the top of the valence band of ZnO films on GaSe substrates. As a result of thermal diffusion of Zn and Al into the GaSe interface layer from ZnO:Al/GaSe heterojunction, electron trap levels located at 0.22 eV and 0.26 eV below the conduction band edge of GaSe, as well as a deep recombination level, responsible for the luminescent emission in the region 1.10 ? 1.40 eV, are created.     

Effect of sodium oleate addition on the morphology of polypropylene-co-polyamide blends

The influence of sodium oleate additives on processing and morphology of polypropylene - co-polyamide (PP/CPA) mixture melts has been investigated. It is shown that sodium oleate is located in the interphase of the components and acts at small additives (up to 3 wt%) as an interfacial tension agent, improving miscibility of polymers, and increasing the kinetic stability of mixtures and the degree of PP dispersion in the co-polyamide matrix. The plasticizing effect on mixture melt was observed at 7 wt% sodium oleate as a reduction of mixture viscosity. The ultrathin PP fibers (microfibers) strictly oriented in the direction of extrusion are the main type of structure produced during extrusion of a PP/CPA mixture. Addition of sodium oleate changed the PP fiber-formation in the CPA matrix: the total number of fibers increased, their diameter and diameter distribution decreased.     

An Implementation of the Mode-Split Traffic-Assignment Method

A software called Optimal Traffic Signal Control System (OTSCS) was developed by us for testing the feasibility of dynamically controlling a traffic signal by finding optimal signal timing to minimize delay at signalized intersections. It also was designed as a research tool to study the learning behavior of artificial neural networks and the properties of heuristic search methods. It consists of a level-of-service evaluation model that is based on an artificial neural network and a heuristic optimization model that interacts with the level-of-service evaluation model. This article discusses the latter model, named the Optimal Traffic Signal Timing Model (OTSTM). The OTSTM was applied to determine optimal signal timing of two-phase traffic signals to evaluate the model's performance. Two search methods were employed: a depth-first search method (an enumeration method) and a direction-search method that the authors developed. It was found that the OTSTM with the direction search resulted in optimal signal timings similar to the depth-first search, which would always produce a global optimal timing. Yet the cost of the direction search, as measured by the CPU time of the computer used for analysis, was found to be much less than the cost of obtaining an optimal solution by the depth-first search cases—more than 10 times less. The study showed that once the artificial neural network is properly trained, heuristic optimal signal timing combined with artificial networks can be used as a decision-support tool for dynamic signal control. This article demonstrates how OTSTM can quickly find an optimal signal-timing solution for two-phase traffic signals.     

Bacterial Mining

Bacterial mining (biomining) represents the use of microorganisms to leach out metals from ores or mine tailings (wastes), followed by the subsequent recovery of metals of interest from the leaching solution. This leaching of metals from ores is a natural process, which can be considerably accelerated by inducing and/or supporting the microbial activity of certain species with the ability to solubilize metals. This process is usually known as biosolubilization and constitutes the basis of many remedial technologies for environments polluted with metals, and also providing the additional potential for recovery of any particular metal of interest. Bacterial mining is part of a vast research field that emerged relatively recently as a border science called biohydrometallurgy. This research field became very important in the context of raw material crises on which technological crises is grafted. In other words, the conventional technologies operating for metal extraction, mainly in the case of lower grade ores, are generally disruptive and less cost-efficient when compared to biomining. Thus, during the last 10-15 years, the interest in biohydrometallurgy, and subsequently in bacterial mining, has increased. The focus has been on two main topics—mineral bioprocessing and biorecovery.     

Microbial Enhanced Oil Recovery (MEOR)

Microbial enhanced oil recovery (MEOR) represents the use of microorganisms to extract the remaining oil from reservoirs. This technique has the potential to be cost-efficient in the extraction of oil remained trapped in capillary pores of the formation rock or in areas not swept by the classical or modern enhanced oil recovery (EOR) methods, such as combustion, steams, miscible displacement, caustic surfactant-polymers flooding, etc. Thus, MEOR was developed as an alternative method for the secondary and tertiary extraction of oil from reservoirs, since after the petroleum crises in 1973, the EOR methods became less profitable. Starting even from the pioneering stage of MEOR (1950s) studies were run on three broad areas, namely, injection, dispersion, and propagation of microorganisms in petroleum reservoirs; selective degradation of oil components to improve flow characteristics; and metabolites production by microorganisms and their effects.     

Influence on the sp3/sp2 character of the carbon on the insertion of nitrogen in RFMS carbon nitride films

RFMS carbon nitride films have been elaborated at several substrate temperatures between 150 °C and 450 °C, where they evolve from a highly resistive to highly conductive comportment. Their local structure has been determined from X-ray photoemission, Raman and infrared spectroscopic results. The films composition has been measured by nuclear reaction analysis and elastic recoil detection.We will correlate the strong modifications of the electronic properties of the films to their well characterized structural changes. We will show how the substrate temperature acts on the incorporation of nitrogen in carboneous RFMS films and which is the resulting consequence on the sp³/sp² character of the carbon network.     

Coronary artery bypass grafting in patients with cerebrovascular disease

The incidence of carotid artery disease in patients undergoing coronary artery bypass grafting appears to be increasing as our population ages. The optimal treatment for these high-risk patients with concomitant carotid and coronary artery disease remains controversial. This review focuses on the management of patients with coexistent carotid and coronary arteriosclerosis. The significance and management of the patient with an asymptomatic carotid stenosis in patients undergoing coronary artery bypass grafting and the role of combined coronary artery bypass grafting and carotid endarterectomy in these patients will be discussed.     

Die organophile Nanofiltration als neue Grundoperation der Fluidverfahrenstechnik

Organic Solvent Nanofiltration is a relatively new unit operation in fluid processing. It addresses a multitude of applications in all sectors of the chemical industry. The benefit for the customer can be a different one depending on the application, therefore, multiple process examples are discussed. Within these, organic solvent nanofiltration can be applied either as a standalone separation process or as a hybrid process in combination with other thermal separation methods.