Fe-Promoted selective methanol synthesis in CO hydrogenation catalyzed on SiO2-supported Ir4Fe and Pd6Fe6 bimetallic carbonyl cluster-derived catalysts

The bimetallic catalysts prepared from Ir₄Fe and Pd₆Fe₆ carbonyl clusters exhibited high activities and selectivities towards methanol from CO + H₂. In contrast, hydrocarbons and CO₂ were preferentially obtained on the catalyst prepared from Fe-rich PdFe₄ cluster. The promotion towards methanol synthesis on the SiO₂-supported Ir₄Fe and Pd₆Fe₆ cluster catalysts was proposed to be associated with Pd-Fe³⁺ and Ir-Fe³⁺ sites located at the metal-support interface.     

Modes of Knowledge Accumulation, Entry Regimes and Patterns of Industrial Evolution

This paper explores the interplay between entry, selection andinnovative learning as determinants of industrial evolution.It proposes a model aimed at capturing some essential featuresof learning and competition as drivers of the dynamics. Usingboth analytical and numerical techniques, the paper disentanglespossible generic properties which robustly hold for a wide rangeof parameterizations. In particular, the paper identifies differentgeneric ‘evolutionary archetypes’, defined by characteristicinteractions between entry/exit regimes, learning and industrialstructures.     

CMOS fully compatible microwave detector based on MOSFET operating in resistive regime

A microwave detector featuring full compatibility with standard CMOS process is presented. It is based on the channel resistance nonlinearity of a MOSFET operating in ohmic regime. The detecting sensitivity is shown to be tuned to below mW power by properly setting the bias voltage of the gate and of the drain of the transistor. Experiments with 180-nm gate length transistor have confirmed detecting operation up to 34GHz. The absence of additional technological steps required for the detector fabrication with respect to a standard CMOS process opens the realm of RF monitoring in products at virtually no cost.     

Experimental assessment of color-rendering indices and color appearance under varying setups

The Color-Rendering Index (CRI) for light source is a quantitative measure of the capability to preserve color appearance of illuminated objects. Recently, CRI has had a renewed interest because of the new LED-based lighting systems. These sources usually have a Color-Rendering Index rather low, but a good preservation of color appearance and a pleasant visual appeal. Various attempts to develop a more reliable new color-rendering index have been done so far, but researchers are still working on the topic. This article presents the open issues related to CRI and discusses some of the approaches available in literature. In order to have a baseline to verify the above points, we present an experiment performed with human observers to assess the appearance preservation of a color under a set of light sources. The test protocol uses 3D reference objects and can be used as an alternative way to assess CRI. The results are then compared with a range of available color rendering indices. The goal is not to make a rank among CRIs, rather to assess their variability relative to human judgment through different setups and light sources.     

Role of body temperature variations in bat immune response to viral infections

The ability of bats to coexist with viruses without being harmed is an interesting issue that is still under investigation. Here we use a mathematical model to show that the pattern of body temperature variations observed in bats between day and night is responsible for their ability to keep viruses in check. From the dynamical systems point of view, our model displays an intriguing quasi-periodic behaviour that might be relevant in making the system robust by avoiding viral escape due to perturbations in the body temperature cycle.     

Si-SiC-ZrB2 ceramics by silicon reactive infiltration

Silicon carbide ceramics obtained by silicon reactive infiltration are nowadays employed within industry in several high temperature applications. Although these ceramics show good thermo-mechanical properties and oxidation resistance, they suffer temperature limitations (1400 °C). At higher temperatures another type of ceramics, commonly known as ultra high temperature ceramics (UHTCs), is under study. These include the transition metal diborides of group IV; one in particular, zirconium diboride, is interesting in certain applications (e.g. aerospace) because of its low relative density. ZrB₂-SiC ceramics show good thermo-mechanical properties and maintain the “protective” passive oxidation regime of their scales over a wide range of temperatures.This paper presents a feasibility study on a manufacturing methodology to produce Si-SiC-ZrB₂ bulk ceramics taking advantage of the reactive infiltration technique. This technique allows lower processing temperatures and near to net shape capability due to low shrinking of the green compacted bodies. C-SiC-ZrB₂ preforms were successfully infiltrated with molten silicon. The resulting Si-SiC-ZrB₂ composites showed promising oxidation behavior, similarly to that reported in other works. Bulk material optimization was performed with a view to manufacturing Si-SiC-ZrB₂ ceramic matrix composites by silicon reactive infiltration in future.     

Structure and characterization of poly[(vinylidene fluoride)‐co‐hexafluoropropene]–(dibutyl phthalate) blends

Blends of poly[(vinylidene fluoride)‐co‐hexafluoropropene] with dibutyl phthalate were examined by wide‐ and small‐angle X‐ray scattering, differential scanning calorimetry and dynamic mechanical spectroscopy, in order to study the influence of amount of plasticizer and the crystallization rate on the crystallinity and lamellar morphology of the copolymer. The dibutyl phthalate seems, at least for the cooling and heating rates used, simply to dilute the crystalline phase without affecting the amount of polymer that is able to crystallize. Furthermore, the small‐angle X‐ray scattering technique points out that the plasticizer mostly enters the amorphous phase either outside or inside the lamellar stacks. © 2001 Society of Chemical Industry     

Real and perceived feet orientation under fatiguing and non-fatiguing conditions in an immersive virtual reality environment

Virtual Reality - Lower limbs position sense is a complex yet poorly understood mechanism, influenced by many factors. Hence, we investigated the position sense of lower limbs through feet...     

Performance models of handover protocols and buffering policies inmobile wireless ATM networks

Due to the connection-oriented nature of the asynchronous transfer mode (ATM), one of the challenges in mobile wireless ATM (WATM) systems is the management of terminal handovers. When ATM connections are reestablished to follow terminals moving between areas covered by distinct base stations, seamless handover protocols are necessary to guarantee that ATM cells are delivered to terminals in the correct order, with cell loss rate and delay that satisfy the contracted quality of service (QoS). A promising approach to meet QoS requirements is based on the use of handover buffers at the (destination) base station, where transmitted cells are stored while the connection is being reestablished. Up to date, only simulation and experimental results are available to determine the performance of such protocols and buffering schemes. This paper presents the first attempt to develop an analytical modeling approach to estimate the performance of handover protocols making use of handover buffers at the base station. By incorporating several approximations, the proposed models allow designers to simultaneously take into account numerous system parameters, including handover buffer size, sustainable and peak cell rates of the ATM connection, terminal offered load, and time needed to reestablish the ATM connection. Analytical performance predictions are shown to closely match results of detailed simulation experiments, thus demonstrating the suitability of the proposed modeling framework for the selection of the most adequate solution to handle handover and provide the QoS required by end users