The hydrocarbon fraction of virgin olive oil and changes resulting from refining

In numerous Spanish virgin olive oils, 6,10-dimethyl-1-undecene, various sesquiterpenes, the series ofn-alkanes from C14 to C35, n-8-heptadecene and squalene are the only less volatile components detected by gas chromatography in the hydrocarbon fraction. In oils from olives of the Arbequine variety, a series ofn-9-alkenes has also been found. In refined oils, notable features are the absence of the most volatile compounds and the appearance of other hydrocarbons produced during the refining process. Among these,n-alkanes, alkadienes (mainlyn-hexacosadiene), stigmasta-3,5-diene, isomerization products of squalene, isoprenoidal polyolefins coming from hydroxy derivatives of squalene and steroidal hydrocarbons derived from 24-methylene cycloartanol were identified. Physical refining produces larger amounts of degradation products and greater losses ofn-alkanes than chemical processing. Squalene is the major hydrocarbon component in all oils, both virgin and refined. The ranges of concentration for the different hydrocarbons found in Spanish virgin olive oils are presented.     

Analysis of the effects of the polymerization route of ethylene‐propylene‐diene rubbers (EPDM) on the properties of polypropylene‐EPDM blends

A comparative study of two ethylene‐propylene‐diene rubbers (EPDM) polymerized by both conventional (Ziegler–Natta catalysts) and new techniques (metallocene catalysts) is presented. For this purpose, thermoplastic elastomers based on isotactic polypropylene (iPP) and EPDM blends at different percentages were prepared and their properties examined. In particular, the processing behavior and mechanical properties are reported. So, the flow properties analyzed by torque value, melt index, and rheological study reveal that the blends containing EPDM synthesized by metallocene catalyst present a smaller viscosity, thus offering better processing behavior. On the other hand, the mechanical properties show that metallocene EPDM rubbers give rise to more elastic materials with a higher deformation at break and resilience as well as a lower compression set. Moreover, the effectiveness of these innovative EPDM rubbers as impact modifiers for PP is demonstrated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 25–37, 2002     

The role of lanthana loading on the catalytic properties of Pd/Al2O3-La2O3 in the NO reduction with H2

The role of La₂O₃ loading in Pd/Al₂O₃-La₂O₃ prepared by sol–gel on the catalytic properties in the NO reduction with H₂ was studied. The catalysts were characterized by N₂ physisorption, temperature-programmed reduction, differential thermal analysis, temperature-programmed oxidation and temperature-programmed desorption of NO.

The physicochemical properties of Pd catalysts as well as the catalytic activity and selectivity are modified by La₂O₃ inclusion. The selectivity depends on the NO/H₂ molar ratio (GHSV = 72,000 h⁻¹) and the extent of interaction between Pd and La₂O₃. At NO/H₂ = 0.5, the catalysts show high N₂ selectivity (60–75%) at temperatures lower than 250 °C. For NO/H₂ = 1, the N₂ selectivity is almost 100% mainly for high temperatures, and even in the presence of 10% H₂O vapor. The high N₂ selectivity indicates a high capability of the catalysts to dissociate NO upon adsorption. This property is attributed to the creation of new adsorption sites through the formation of a surface PdO_x phase interacting with La₂O₃. The formation of this phase is favored by the spreading of PdO promoted by La₂O₃. DTA shows that the phase transformation takes place at temperatures of 280–350 °C, while TPO indicates that this phase transformation is related to the oxidation process of PdO: in the case of Pd/Al₂O₃ the O₂ uptake is consistent with the oxidation of PdO to PdO₂, and when La₂O₃ is present the O₂ uptake exceeds that amount (1.5 times). La₂O₃ in Pd catalysts promotes also the oxidation of Pd and dissociative adsorption of NO mainly at low temperatures (<250 °C) favoring the formation of N₂.     

Robust flat filtering DSP based control of the boost converter

The article deals with the design and implementation of a flat filter tracking digital controller for a boost dc-dc power converter. A highly perturbed switched boost converter circuit is shown to be efficiently controlled, in a trajectory tracking task for its non-minimum phase output, by means of a suitable linear filter, here addressed as a flat filter. Flat filtering is a natural robust version of generalized proportional integral control (GPIC) by which the effects of arbitrary time varying exogenous disturbances, unknown endogenous nonlinearities and un-modeled dynamics can be jointly attenuated in a conceptually similar fashion to observer-based active disturbance rejection control (ADRC) and algebraic identification based model free control (MFC) but: a) without using extended state observers and b) respecting the original system order in a time-varying simplified model while avoiding algebraic estimation techniques. The proposed control technique based on the TMS320F28335 digital signal processor chip is tested by means of realistic simulations and experimental setup.     

Synergistic photoluminescent interaction of Si and CdTe quantum dots

Microsystem Technologies - We report the synergistic photoluminescent effect observed in heterogeneous colloidal solutions comprising different volumetric concentrations of Si and CdTe quantum dots...     

Plasmon resonant amplification of a hot electron-driven photodiode

Nano Research - We report plasmon resonant excitation of hot electrons in a photodetector based on a metal/oxide/metal (Au/Al2O3/graphene) heterostructure. In this device, hot electrons, excited...     

Interlocking, Ribbing and Folding: Explorations in Parametric Constructions

This paper presents three projects involving the design and fabrication of architectural structures through the use of different parametric software and digital manufacturing methods. The first project is a flexible partition composed of interlocking elements shaped using a laser-cutter. The second project is a university exhibition unit made with various wooden panels manufactured through a computer numerical controlled (CNC) system. The third project is a system of metal sheets folded by digital machines to create urban circulation spaces. The three works develop a parametric programming of geometry based on certain technical factors, enabling the recognition of patterns of interaction between formal and constructive issues involved in the definition of shapes through parametric controls. Differences in materials and processes are contrasted by similarities of function and conditions involved, creating a system of local, global, productive and environmental parameters that produces a repertoire of self-similar dimensions and variations as well as multiple possibilities of initial setups and final configurations. It suggests a specific field of design exploration focusing on the development of differentiated components and variable architectural configurations, in a kind of open parametric system.