A web-based decision support system for waste lube oils collection and recycling

This paper presents a web-based decision support system (DSS) that enables schedulers to tackle reverse supply chain management problems interactively. The focus is on the efficient and effective management of waste lube oils collection and recycling operations. The emphasis is given on the systemic dimensions and modular architecture of the proposed DSS. The latter incorporates intra- and inter-city vehicle routing with real-life operational constraints using shortest path and sophisticated hybrid metaheuristic algorithms. It is also integrated with an Enterprise Resource Planning system allowing the utilization of particular functional modules and the combination with other peripheral planning tools. Furthermore, the proposed DSS provides a framework for on-line monitoring and reporting to all stages of the waste collection processes. The system is developed using a web architecture that enables sharing of information and algorithms among multiple sites, along with wireless telecommunication facilities. The application to an industrial environment showed improved productivity and competitiveness, indicating its applicability on realistic reverse logistical planning problems.     

Genetic transformation of xylose-fermenting yeastPichia stipitis

Applied Biochemistry and Biotechnology - A plasmid-mediated transformation system has been developed for the xylose-fermenting yeastPichia stipitis. We found that plasmid vectors containing...     

Electron difference densities and chemical bonding

In view of recent advances in X-ray technology it may be possible to deduce information regarding chemical bonding from experimentally determined electron densities. The construction of difference density maps represents a possible intermediate step in attaining this goal, but unresolved questions exist regarding appropriate definitions and interpretations of such maps. To shed light on these problems, theoretical difference densities are determined by ab-initio calculations for the molecules H₂, He₂, Li₂, Be₂, N₂ and F₂ at various internuclear distances. An examination of these difference density maps shows that the identification of those features of molecular electronic densities which are related to chemical bonding requires a judicious construction and a careful analysis of difference densities between molecules and their constituent atoms. Chemically relevant deformations can be small compared to density differences between different components of degenerate atomic groundstates and, consequently, chemical information can be swamped when difference densities are formed with spherically averaged atoms. To avoid such artifacts, oriented unaveraged atomic states must be subtracted for the formation of meaningful Chemical Difference Densities. The latter are explainable by means of a partitioning in terms of contributions from non-bonded inner shells, from lone pairs and from sigma and pi bonding shells. Such partitionings can be obtained through decompositions in terms of natural orbitals from correlated wavefunctions. Canonical SCF orbitals prove to be considerably less effective. Internuclear distances are found to have a great influence upon difference densities regardless of the attractive or repulsive nature of the interactions.     

Fourier transform infrared spectroscopic characterisation of heavy metal-induced metabolic changes in the plant-associated soil bacterium Azospirillum brasilense Sp7

Structural and compositional features of whole cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp7 under standard and heavy metal-stressed conditions are analysed using Fourier transform infrared (FTIR) spectroscopy and compared with the FT-Raman spectroscopic data obtained previously [J. Mol. Struct. 563–564 (2001) 199]. The structural spectroscopic information is considered together with inductively coupled plasma-mass spectrometric (ICP-MS) analytical data on the content of the heavy metal cations (Co²⁺, Cu²⁺ and Zn²⁺) in the bacterial cells. As a bacterial response to heavy metal stress, all the three metals, being taken up by bacterial cells from the culture medium (0.2 mM) in significant amounts (ca. 0.12, 0.48 and 4.2 mg per gram of dry biomass for Co, Cu and Zn, respectively), are shown to induce essential metabolic changes in the bacterium revealed in the spectra, including the accumulation of polyester compounds in bacterial cells and their enhanced hydration affecting certain IR vibrational modes of functional groups involved.     

Preparation and characterization of electrophoretically deposited high-temperature superconductor coatings

The high-temperature superconductor, YBa₂Cu₃O_7–x (x = 0.1–0.2) [YBCO], was prepared using an optimized calcination and sintering process. Thin layers of a few microns of this material were deposited on a silver substrate by applying a simplified electrophoretic deposition technique in a suspension of the fine, < 10 m, superconductor powder in a non-aqueous liquid. To get a uniform and strongly adherent coating, the deposition process is repeated several times, followed by an appropriate sintering procedure. The initially prepared YBCO powder and the coatings produced were characterized for their superconducting properties by X-ray diffraction analysis (XRD), magnetization measurements with a Superconducting Quantum Interference Device (SQUID) and electrical resistivity measurements. By scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) the grain size of the YBCO film, its thickness and impurity content, respectively, were estimated.     

HPLC study for evaluating the significance of pH in the inhibiting effect of phosphate buffer on the leaching pattern of resin composites

An HPLC method was applied to evaluate the inhibiting effect of phosphate buffer on the leaching pattern of resin composites and the significance of pH levels during the storage period in the solutions. Ten (10) disk-shaped specimens (2?mm?×?12?mm diameter) from Evetric restorative resin composite were immersed by means of a silk string in each of the following solutions: Distilled water (solution A), phosphate buffer of pH?=?4.5 (solution B) and phosphate buffer of pH?=?6.8 (solution C). After storage for 7, 30 and 60 days’ period, the eluates were examined by means of High Performance Liquid Chromatography (HPLC) at each time interval. The storage of the resin composite specimens in the phosphate buffer solution demonstrated an inhibiting effect on the leaching pattern compared to the distilled water solution. The results of this study suggest that HPLC is a useful tool to investigate the effect of the pH value of phosphate buffer solution, which resembles saliva, on the leaching pattern of resin composites.     

125-mJ diode-pumped injection-seeded Ho:Tm:YLF laser

We describe a diode-pumped, room-temperature Ho:Tm:YLF power oscillator with an optical-to-optical efficiency of 0.03. A Q -switched output energy of as much as 125 mJ at 6 Hz with a pulse width of 170 ns was obtained. Single-frequency, nearly transform-limited operation of the laser was achieved by injection seeding. Laser performance as a function of laser rod temperature and pump intensity was also investigated. The high power and high beam quality of this laser make it well suited for use as a coherent wind lidar transmitter on a space platform.     

Complexation of Indole-3-acetic Acid with Iron(III): Influence of Coordination on the π-Electronic System of the Ligand

 The iron(III) complex of indole-3-acetic acid (1) was prepared, and its physicochemical properties, mode of iron(III) coordination, and electronic structure were studied using UV/Vis, diffuse reflectance infrared Fourier transform (DRIFT), and transmission ⁵⁷Fe M?ssbauer spectroscopic techniques. The data obtained provide evidence that iron(III) is not only coordinated by the carboxylic O-donor atom, but also via the conjugated π-electronic system of the pyrrole moiety involving both the non-shared electronic pair of the heteroatom and the C(2)*C(3) double bond. Considering the well-known increased sensitivity of the pyrrole residue in indole derivatives to oxidation as compared to the benzene ring, as well as the formation of a triple complex (peroxidase-1-O₂) proposed for the enzymatic 1 oxidative degradation mechanism involving as a key step the Fe³⁺ → Fe²⁺ transition in the enzyme form as discussed in literature, it is concluded that iron(III) coordination with 1 can influence the redox properties of the pyrrole ring by affecting its π-electronic system.     

Adaptive multi-restart Tabu Search algorithm for the vehicle routing problem with cross-docking

This paper deals with a multi-source vehicle routing problem with a cross-docking facility, and studies open and closed network configurations as well as practically relevant dependency rules and consolidation decisions. Given a set of supplier–customer pairs with known demands, the aim is to design minimum cost routes for the transportation of products via a cross-dock. Vehicles cannot travel directly from suppliers to customers, and thus, products arriving from inbound vehicles are sorted and consolidated onto outbound vehicles. The proposed method utilizes an adaptive multi-restart local search framework. For this purpose, a Tabu Search algorithm is employed, while the execution of the re-starting mechanism is based on the information extracted from a reference set of solutions. Computational experiments illustrate the efficiency and effectiveness of the proposed method. Compared to existing results, new improved upper bounds are reported.