102,214 research outputs found
An X-ray absorption spectroscopy study of the FeK edge in nanosized maghemite and in Fe2O3-SiO2 nanocomposites
No full textThe structural evolution of Fe2O3-SiO2 nanocomposite samples prepared using the sol-gel method have been studied by EXAFS (extended X-ray absorption fine structure) and XANES (X-ray absorption near edge structure) techniques in comparison with pure nanosized and microcrystalline maghemite samples. EXAFS data show that the difference between nanosized and microcrystalline maghemite is due to an increase of disorder of the superficial sites while no decrease of coordination numbers was detected. EXAFS and XANES data of the nanocomposite thermally treated at 900 degrees C indicate that the sample is constituted by maghemite nanoparticles embedded into amorphous silica while the sample thermally treated at 300 degrees C contains an amorphous precursor which is very likely to be ferrihydrite. No interactions between the metal oxide nanoparticles and the silica network are present since the EXAFS spectra of the nanocomposite samples can be interpreted as only having Fe-O and Fe-Fe interactions
IoT in the hospitality industry: exploring theoretical and practical implications
No full textTourism is currently undergoing a digital transition that is transforming it at a rapid pace. The
Internet of Things has the capability to completely revolutionise tourist experiences by allowing
visitors to connect digitally with local inhabitants via sensors and cameras linked to buildings
and devices throughout towns and neighbourhoods. The main aim of this chapter is to discuss
the IoT applications in the hospitality sector, as well as their organisational consequences. After
introducing a few basic ideas and terminologies, we discuss the growth of IoT in the tourism
ecosystem, tracing a few exemplary scenarios and identifying the important players. The focus
then shifts to the IoT's possibilities in the hospitality industry, where smart room design and
development are already underway. The Marriott case study analysis is presented in the
chapter's centre portion as trailblazing evidence of an important paradigm shift toward
ubiquitous smart services in high-end hotels. Finally, we discuss privacy concerns and the
theoretical and practical implications regarding the adoption of the IoT in hospitality
Solid-state reaction induced by milling of a mixture of cobalt and boron powders
No full textA mixture of polycrystalline elemental cobalt and boron powders in the atomic ratio Co67B33 was mechanically milled for 150 h. The milled powders were examined by X-ray diffraction, extended X-ray absorption fine structure spectroscopy and differential scanning calorimetry. Two steps where energy was regulated by different full/void volume ratio in the vials were carried out. In the first milling step (f/v=1/1) amorphization involves only a portion of the starting powder and reaches a steady state after 25 h. More energetic conditions (f/v=1/5) lead to almost complete amorphization of the sample after 70 h, and in the final stages the formation of crystalline t-Co2B is observed. Then a steady state, in which both amorphous and crystalline phases coexist, is reached
Bilanciare risultati economici, gestione delle risorse umane e sostenibilità: prospettive dal contesto italiano
No full textInfluence of dehydroepiandrosterone on G-6-PD activity and 3H-thymidine uptake of human lymphocytes in vitro
No full textDehydroepiandrosterone (DHEA) was found to inhibit experimental cancer development in mouse and rat lung, colon and mammary gland. Since DHEA is a potent inhibitor of mammalian G-6-PD, the hypothesis that the compound could inhibit cell proliferation through an inhibition of the pentose phosphate pathway has been formulated. We studied the effects of DHEA on the proliferation in vitro of human lymphocytes induced by several mitogens (PHA, ConA and PWM), measuring 3H-thymidine uptake. DHEA inhibited 3H-thymidine uptake of mitogen-stimulated cells from both G-6-PD+ and G-6-PD- (mediterranean type deficiency) individuals in a dose-dependent and reversible fashion. The inhibitory effect was found even if DHEA was added to cells in the last hours of culture, simultaneously with the addition of 3H-thymidine. These data suggest that the inhibition of thymidine uptake induced by DHEA on human lymphocytes probably does not depend on the inhibition of G-6-PD
Mechanical alloying of cobalt and boron powders
No full textMechanical alloying was performed on elemental cobalt and boron powders in the atomic ratio Co67B33. The process was monitored by X-ray diffraction spectra taken at regular time intervals. The progressive lowering of the crystalline peaks' intensity accompanied by the formation of an amorphous halo was observed; in the final stages peaks due to crystalline t-Co2B began to emerge. With the exception of the time scale, the evolution of the system was similar to that of a previous preparation carried out under different energy conditions. The structure functions and radial distribution functions were calculated from quantitative X-ray diffraction data taken near complete sample amorphization to follow the details of the milling process at these stages
Amorphous metallic powders prepared by chemical reduction of metal ions with potassium borohydride in aqueous solution
No full textAmorphous metal-metalloid powders have been prepared by chemical reduction of Fe2+, Co2+, and Ni2+ ions with potassium borohydride in aqueous solution. The chemical composition of the samples, TM-B-O, varies with the metal and with the preparation steps. The as-prepared Co-B-O and Ni-B-O samples are definitely amorphous, while the Fe-B-O sample mainly consists of bcc α-Fe. Crystallization of the samples through thermal treatment has been investigated by X-ray diffraction. The Co-B-O sample evolves toward fee metallic cobalt accompanied first by metastable o-Co3B and, at high temperature, by t-Co2B. The Ni-B-O sample gives rise to fee metallic Ni and o-Ni3B, which decomposes at higher temperatures. Iron borides are not detected in the thermal treatment of the Fe-B-O sample. No evidence of metal oxides is present in all the samples, thus suggesting the prevalent bonding of oxygen to boron
Il problema è come pensiamo al problema: Gestire le tensioni con il pensiero paradossale
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