Olive mill wastewaters decontamination based on organo-nano-clay composites

Green composites for environmental applications were successfully prepared by intercalation of the biosurfactant Quillaja saponin onto montmorillonite mineral clay on varying pH and surfactant/clay ratio. Equilibrium adsorption isotherms were constructed and the system was characterized by performing TGA and XRD analyses.The efficiency of the surfactant-modified clay in the removal of the organic content present in olive mill wastewaters (OMW) was evaluated by means of spectrophotometric measurements. The interest for this cogent issue comes from the consideration that, despite their high pollutant content, OMW can be considered as a potential resource of several organic compounds which can be recovered for a wide array of pharmaceutical and industrial applications. Two different strategies were proposed. In the first one, dried surfactant/clay hybrids were added to the batch samples under continuous stirring, while in the second alternative approach the organoclays were packed in chromatography column filled with multiple alternate layers of sand and organoclay.These studies revealed the efficacy of the methods used and suggested that the modification of the montmorillonite clay substrate significantly improves the performance of the clay.     

Automatic phase stepping in fiber-optic ESPI by closed-loop gainswitching

In this paper, we describe a new technique for automatic phase stepping in fiber-optic Electronic Speckle Pattern Interferometry (ESPI), useful in both single-point and imaging configurations. The proposed technique is based on closed-loop switching of the gain sign in the control loop used to stabilize the reference wavefront phase, with the aid of a Proportional-Integral (P.I.) controller. Simulation and experimental results are compared, showing that by a synchronization signal or by a proper choice of the feedback loop parameters, a sequence of π/2 steps of the reference wavefront phase, all of the same sign, is obtained, The residual fluctuation of each phase step amounts to ±2.5 mr over a bandwidth of 200 Hz. This level of phase stability is well suited for ESPI applications     

Quantum efficiency and admittance spectroscopy on Cu(In,Ga)Se2 solar cells

We investigate the electronic transport properties of Cu(In,Ga)Se₂ solar cells by means of quantum efficiency and temperature dependent admittance spectroscopy. A simple evaluation scheme of quantum efficiency data is introduced which accounts for recombinatoric losses in the Us buffer layer and in the Cu(In,Ga)Se₂ absorber. By admittance spectroscopy, we find that the controlled incorporation of Na into the absorber material leads to a shallow acceptor state at about 75 meV above the valence band.     

Inclusion of Methoxybutropate in β-and Hydroxypropyl β-Cyclodextrins: Comparison of Preparation Methods

Interactions between methoxybutropate and β-cyclodextrin or hydroxypropyl β-cyclodextrin and the possibility of obtaining inclusion complexes have been evaluated by phase solubility diagram, HPLC, DSC, and x-ray diffractometry. Solid inclusion complexes were prepared by spray drying, kneading, and solid dispersion. The dissolution profiles of the obtained powders were studied in order to define the most appropriate cyclodextrin preparation method and molar ratio to use in the production of methoxybutropate inclusion complexes     

General purpose software for probability computations—A virtual machine approach

The application of probability techniques in structural engineering has seen ample development in the last decade. Yet, the software used for engineering probability computations often lacks generality. The functional needs to be satisfied by general purpose software for engineering applications of probability methods are presented. An analysis of these needs suggests a software design philosophy based on the concept of a software virtual machine for probability computations. The virtual machine architecture and software design are explained. An example problem, in seismic risk analysis, solved with software based on this design is described.     

The three-dimensional neutron kinetics coupled with thermal-hydraulics in RBMK accident analysis

The RBMK core is a complex ensemble of high-pressure high-temperature tubes, graphite bricks, low-pressure low-temperature control rod tubes, graphite interstitial gas passages. An about 7 MPa boiling light water crosses the around 19 m long vertical tubes (7 m active length). The lattice consisting of graphite columns and hydraulic channels is bounded by the reactor cavity whose resistant elements are the metal cylindrical tank and thick circular top and bottom plates with proper holes for the passage of tubes.Related to a typical water cooled reactor, the peculiarities of the RBMK core can be summarized as follows: (a) large dimensions – the overall core volume is by far the largest for a nuclear power plant (NPP) producing electricity; (b) use of separate moderator and coolant constituted by graphite and light boiling water, respectively – the boiling water mostly absorbs neutrons in this environment leading to the (small) positive void reactivity coefficient; (c) presence of water channels very close to each other containing coolant at different temperatures (543–557 K and 350 K for fuel channels (FC) and control and protection system (CPS) channels, respectively); (d) presence of core-wide radial, core-wide axial and local temperature gradients in the graphite bricks with temperature values in the range 330–650 K with the high-temperature values justified by the neutron moderation and gamma-heating processes.Owing to the above peculiarities, the development and the use of a three-dimensional neutron kinetics code (3D NK) coupled with a one-dimensional thermal-hydraulic (TH) code is essential in RBMK safety analyses.Two approaches have been used within the present context, i.e. use of coupled 3D NK-TH codes to support the accident analysis in the RBMK as discussed in the first of the companion papers in this journal volume: application of Korsar-Bars making use of the Unk code to derive λ-matrices needed for Bars and of Relap5/3D-Nestle making use of the Helios code to derive the macroscopic cross-sections.Bounding transient analyses of accident scenarios including control rod withdrawal, various Loss of Coolant Accident (LOCA) and discharge of the control rod circuit, have been completed. In all of the analysed cases, starting from nominal operating conditions, modest fission power time gradients have been found, i.e. characterized by time derivative values for local and global power changes substantially smaller than current values accepted in safety analyses of light water reactors.     

Tampering in RFID: A Survey on Risks and Defenses

RFID is a well-known pervasive technology, which provides promising opportunities for the implementation of new services and for the improvement of traditional ones. However, pervasive environments require strong efforts on all the aspects of information security. Notably, RFID passive tags are exposed to attacks, since strict limitations affect the security techniques for this technology. A critical threat for RFID-based information systems is represented by data tampering, which corresponds to the malicious alteration of data recorded in the tag memory. The aim of this paper is to describe the characteristics and the effects of data tampering in RFID-based information systems, and to survey the approaches proposed by the research community to protect against it. The most important recent studies on privacy and security for RFID-based systems are examined, and the protection given against tampering is evaluated. This paper provides readers with an exhaustive overview on risks and defenses against data tampering, highlighting RFID weak spots and open issues.     

MATTER: A tool for generating end-to-end IoT test scripts

Software Quality Journal - In the last few years, Internet of Things (IoT) systems have drastically increased their relevance in many fundamental sectors. For this reason, assuring their quality is...     

Surface Reconstruction Engineering with Synergistic Effect of Mixed-Salt Passivation Treatment toward Efficient and Stable Perovskite Solar Cells

Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI₂. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions.