27,069 research outputs found
Gender stereotypes in occupational choice: a cross-sectional study on a group of Italian adolescents [Erratum]
No full textRamaci T, Pellerone M, Ledda C, Presti G, Squatrito V, Rapisarda V. Psychol Res Behav Manag. 2017;10:109–117. On page 116, Reference section, an error was introduced in the numbering regarding reference 44. The correct reference details are:44. Wraga M, Duncan L, Jacobs EC, Helt M, Church J. Stereotype susceptibility narrows the gender gap in imagined self-rotation performance. Psychon Bull Rev. 2006;13(5):813–819.The reference citation in the main text is correct.Read the original articl
A Concerted Electrochemical and Theoretical Investigation of the Ag/TiO2 nano-heterojunction
No full textSuitably designed nano-heterojunctions are able to enhance synergistic functionalities of different materials yielding to “brave new systems” with innovative and sometimes unexpected physicochemical properties [1]. However, the complete understanding of these devices has to be deeply studied. In this work, a concerted theoretical and electrochemical investigation is proposed to gain insights into a metal-semiconductor interface, namely that created by the silver/anatase hybrid nanocomposite, a promising material for advanced sensing applications [2]. In particular, it provided the first photorenewable and anti-fouling sensor device, enhancing the analytical limits in terms of accuracy, sensitivity, detection limits, and photoactivity [3]. Furthermore, the hybrid material is proven to be extremely robust against aging, showing complete regeneration, also after one-year storage.
The electrochemical/electroanalytical virtues of the Ag/TiO2 junction were evaluated in terms of current densities and reproducibility, providing their explanation at the atomic-scale level and demonstrating how and why the final device can act as silver-cation positive electrode [4]. Moreover, Cyclic Voltammetry and Electrochemical Impedance Spectroscopy were used in combination with periodic plane-wave DFT calculations, giving comparable qualitative but also quantitative results. In particular, we theoretically estimated the overall amount of electron transfer toward the semiconductor side of the interface at equilibrium and suitably designed electrochemical experiments, which strictly agree with the theoretical charge transfer estimates. Moreover, photoelectrochemical measurements and theoretical predictions show the unique permanent charge separation occurring in the device [4].
[1] A.V. Emeline, V.N. Kuznetsov, V.K. Ryabchuk, N. Serpone, Environ. Sci. Pollut. Res., 2012, 19, 3666–3675.
[2] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst, 2015, 140, 1486–1494.
[3] V. Pifferi, G. Soliveri, G. Panzarasa, G. Cappelletti, D. Meroni, L. Falciola, Anal. Bioanal. Chem., 2016, 408, 7339–7349.
[4] G. Di Liberto, V. Pifferi, L. Lo Presti, M. Ceotto, L. Falciola, J. Phys. Chem. Lett., 2017, 8, 5372–5377
A Concerted Investigation For Metal/Semiconductor Nanointerface : Interlayer Charge Transfer At Ag/TiO2
No full textIn the field of hybrid materials, suitably designed nanoheterojunctions enhance synergistic functionalities and allow to obtain “brave new materials” with physicochemical properties that are not simply the addition of the precursors’ ones, but are completely new, different, and sometimes unexpected. For these reasons, the use of them has paved the way toward promising applications in many fields, such as electrocatalysis, photocatalysis, electroanalysis, and environmental chemistry, impacting on the everyday life [1].
However, research on such systems is most often dominated by trial and error procedures, while a deep atomistic understanding of the phenomena inside the junction region driving appropriate design of the final device is missing. Here, a concerted theoretical and electrochemical investigation is proposed to gain insights into the important class of heterojunctions made by metal-semiconductor interfaces.
The presented case of study is the silver/anatase hybrid nanocomposite, a very promising material for advanced sensing applications [2]. Considering that in most cases titania semiconductors are useless in electroanalysis and silver is subject to fouling and oxidation/passivation, such broad outcomes were totally unexpected. Specifically, Ag/TiO2 interfase provided the first photorenewable sensor device, pushing the limits in terms of accuracy, sensitivity, detection limits, and photoactivity [3]. Despite the ongoing research, a quantitative and comprehensive understanding of the physics behind this nanocomposite is still missing, thus preventing its full exploitation and the extension of the same paradigm to other systems and devices.
In particular, cyclic voltammetry and electrochemical impedance spectroscopy are used in combination with periodic plane-wave DFT calculations, giving comparable qualitative, but also quantitative results. We measure the exceptional electrochemical virtues of the Ag/TiO2 junction in terms of current densities and reproducibility, providing their explanation at the atomic-scale level and demonstrating how and why silver acts as a positive electrode [4]. We theoretically estimate the overall amount of electron transfer toward the semiconductor side of the interface at equilibrium and suitably designed electrochemical experiments strictly agree with the theoretical charge transfer estimates. Moreover, photoelectrochemical measurements and theoretical predictions show the unique permanent charge separation occurring in the device, possible because of the synergy of Ag and TiO2, which exploits in a favorable band alignment, in a smaller electron–hole recombination rate and in a reduced carrier mobility when electrons cross the metal–semiconductor interface. Finally, the hybrid material is proven to be extremely robust against aging, showing complete regeneration, even after one year [4].
[1] A.V. Emeline, V.N. Kuznetsov, V.K. Ryabchuk, N. Serpone, Environ. Sci. Pollut. Res. 19 (2012) 3666–3675.
[2] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst 140 (2015) 1486–1494.
[3] V. Pifferi, G. Soliveri, G. Panzarasa, G. Cappelletti, D. Meroni, L. Falciola, Anal. Bioanal. Chem. 408 (2016) 7339–7349.
[4] G. Di Liberto, V. Pifferi, L. Lo Presti, M. Ceotto, and L. Falciola, J. Phys. Chem. Lett. 8 (2017) 5372–5377
Silver nanoparticles/nanostructured TiO2 interface: a photo-renewable “silver-ions electrode” for neurotransmitters detection
No full textIn recent years the use of hybrid nanomaterials, characterized by unprecedented behaviours and features, has paved the way towards promising applications in many fields. The synergistic functionalities provided by these nanocomposites, based on the generation of heterojunctions, allow to obtain “brave new materials”, with physico-chemical properties which are not only the sum of the precursors’ ones. Although the Literature has used plenty of these new devices for different applications, the complete understanding of the phenomena deeply located inside these interfaces is still to be clarified.
In this context, we propose this theoretical and electrochemical concerted study to help in the understanding of the Ag-TiO2 interface properties. In particular, silver nanoparticles were embedded in a TiO2 (anatase polymorph) photoactive layer in a sandwich-like nanostructured electrode, which was (photo)electrochemically characterized by cyclic voltammetry and electrochemical impedance spectroscopy. According to the theoretical and experimental findings it could be concluded that the device may be considered as a “positively charged silver nanoparticles-based electrode”, with positively ionized surface silver atoms protected by the titania layer, which holds a partial negative charge. The final sensor performed efficiently in the electroanalytical determination of some neurotransmitters in simulated biological matrices presenting interesting results in terms of sensitivities, detection limits and photoactivity, providing also the first photo-renewable sensor device, capable of overcoming the fouling and passivation of the electrode surface, an unavoidable drawback during the detection of this kind of analytes [1-3].
Acknowledgments
This work has been supported by Fondazione Cariplo (Italy), grant no. 2014-1285 and by the MIUR National Project PRIN 2012 (prot. 20128ZZS2H).
References
1. G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst, 2015, 140, 1486-1494.
2. V. Pifferi, G. Soliveri, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, L. Falciola, RSC Advances, 2015, 5, 71210-71214.
3. V. Pifferi, G. Soliveri, G. Panzarasa, G. Cappelletti, D. Meroni, L. Falciola, Anal. Bioanal. Chem., 2016, 7339-7349
Electrochemical and theoretical investigation of the silver nanoparticles/TiO2 interface: the “silver-ion electrode”
No full textA sandwich-like structure electrode of silver nanoparticles embedded in a titania (anatase polymorph) photoactive layer was prepared [1-2] and electrochemically characterized by cyclic voltammetry and electrochemical impedance spectroscopy.
In comparison with literature data on bare silver nanoparticles-modified electrodes [3-5], the new device features a pronounced electrocatalytic effect on the silver oxidation peak (Fig. a) together with a great increase in the current intensity. Plane-wave DFT calculations, performed using the VASP code, described the composite junction as a distorted bulk Ag structure, commensurate with the periodicity of the (101) face of the I41/amd TiO2 polymorph. The silver atoms close to the semiconductor were found to gain a partially positive charge, quickly decreasing with the distance from the TiO2 surface.
These joint theoretical and experimental evidences demonstrate that the device could be considered as a “positively charged silver nanoparticles-based electrode”, with positively ionized surface silver atoms protected by the titania layer, which holds a partial negative charge. This peculiar electrode structure shows interesting properties, among which self-cleaning ability, to be conveniently used for sensor applications.
References
[1] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst, 140, (2015), 1486 – 1494.
[2] V. Pifferi, G. Soliveri, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, L. Falciola, RSC Advances, 5, (2015), 71210 – 71214.
[3] O. S. Ivanova, F. P. Zamborini, J. Am. Chem. Soc., 132, (2010), 70–72.
[4] G. Chang, J. Zhang, M. Oyama, K. Hirao, J. Phys. Chem. B, 109, (2005), 1204-1209.
[5] S.E. Ward Jones, F.W. Campbell, R. Baron, L. Xiao, R.G. Compton, J. Phys. Chem. C, 112, (2008), 17820–17827.
Acknowledgements
This work has been supported by Fondazione Cariplo (Milano, Italy), grant no. 2014-1285. We acknowledge the CINECA and the Regione Lombardia award under the LISA initiative (grant SURGREEN) for the availability of high performance computing resources. We also thank the Chemistry Department for funding through the Development Plan of Athenaeum grant – line B1 (UNIAGI 17777)
A concerted investigation of the interlayer charge transfer in Silver/Anatase nanocomposites
No full textThe use of hybrid nanomaterials, characterized by unprecedented behaviors and features, has now paved the way toward promising applications in many fields, such as electrocatalysis, photocatalysis, electroanalysis, and environmental chemistry, impacting on the everyday life [1].
Suitably designed nanoheterojunctions enhance synergistic functionalities and allow one to obtain “brave new materials” with physicochemical properties that are not simply the addition of the precursors’ ones but are completely new, different, and unexpected. However, research on such devices is most often dominated by trial and error procedures, while a deep atomistic understanding of the phenomena inside of the junction region driving appropriate design of the final device is missing.
Here, a concerted theoretical and electrochemical investigation is proposed to gain insights into the important class of heterojunctions made by metal-semiconductor interfaces. Specifically, this approach is applied to the case of silver/anatase hybrid nanocomposite, a very promising material for advanced sensing applications [2].
In particular, we measure the exceptional electrochemical virtues of the Ag/TiO2 junction in terms of current densities and reproducibility, providing their explanation at the atomic-scale level and demonstrating how and why silver acts as a positive electrode [3]. Using periodic plane-wave DFT calculations, we estimate the overall amount of electron transfer toward the semiconductor side of the interface at equilibrium. Suitably designed (photo)electrochemical experiments strictly agree, both qualitatively and quantitatively, with the theoretical charge transfer estimates. The unique permanent charge separation occurring in the device is possible because of the synergy of Ag and TiO2, which exploits in a favorable band alignment, in a smaller electron–hole recombination rate and in a reduced carrier mobility when electrons cross the metal–semiconductor interface. Finally, the hybrid material is proven to be extremely robust against aging, showing complete regeneration, even after 1 year [3].
[1] A.V. Emeline, V.N. Kuznetsov, V.K. Ryabchuk, and N. Serpone, Environ. Sci. Pollut. Res. 19 (2012) 3666–3675.
[2] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, and L. Falciola, Analyst 140 (2015) 1486–1494.
[3] G. Di Liberto, V. Pifferi, L. Lo Presti, M. Ceotto, and L. Falciola, J. Phys. Chem. Lett. 8 (2017) 5372–5377
Silver cations electroanalytical sensor: sensitivity and selectivity iIn the detection of neurotransmitters
No full textA composite electrode with a sandwich structure combining the properties of silver nanoparticles and a titania (anatase polymorph) photoactive layer was prepared [1-2] and electrochemically characterized by cyclic voltammetry and electrochemical impedance spectroscopy. A pronounced electrocatalytic effect was observed along with a great increase in the current intensity of the silver oxidation peak (Figure 1). Results are compared with literature data on bare silver nanoparticles [3-5].
Theoretical DFT calculations, performed using the VASP code [6], described the composite junction as a distorted bulk Ag structure, commensurate with the periodicity of the (101) face of the I41/amd TiO2 polymorph. The silver atoms close to the semiconductor gain a partially positive charge [7], which quickly decreases with the distance from the TiO2 surface.
This joint theoretical and experimental study allows us to conclude that the device could be considered as a “silver cations electrode”, with silver ions protected by the titania layer, which holds a partial negative charge. This peculiar electrode structure can be conveniently used for sensor applications. For example, we successfully applied our device for the determination of neurotransmitters such as dopamine, norepinephrine and serotonin in simulated biological matrices (liquor, serum and urine). Our optimized analytical methodology is not only characterized by high sensitivity and low detection limits (around 0.03 μM) but also by high selectivity in the presence of high concentrations of conventional interferents (uric and ascorbic acids).
Moreover, the device shows under UV light self-cleaning properties of its titania overlayer, with complete removal of fouling, originated by the chemisorption of analytes and byproducts. Irradiating the device with UVA light, the initial sensor sensitivity was restored, making it reusable and suggesting its employment in integrated monitoring systems.
Acknowledgements
This work has been supported by MIUR (Ministero dell’Istruzione, dell’Università e della Ricerca) in the framework of the PRIN 2012 Project (20128ZZS2H).
References
[1] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst 140, 2015, pp 1486 – 1494.
[2] V. Pifferi, G. Soliveri, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, L. Falciola, RSC Advances 5, 2015, pp 71210 – 71214.
[3] O. S. Ivanova, F. P. Zamborini, J. Am. Chem. Soc. 132, 2010, pp 70–72.
[4] G. Chang, J. Zhang, M. Oyama, K. Hirao, J. Phys. Chem. B 109, 2005, pp 1204-1209.
[5] S.E. Ward Jones, F.W. Campbell, R. Baron, L. Xiao, R.G. Compton, J. Phys. Chem. C 112, 2008, pp 17820–17827.
[6] G. Kresse, D. Joubert, Phys. Rev. B: Condens. Matter 59, 1999, pp 1758−1775.
[7] W. Tang, E. Sanville, and G. Henkelman, J. Phys. Condens. Matter 2009, 21, 084204
Interlayer Charge Transfer At Metal/Semiconductor Interface: A Concerted Investigation for Ag/TiO2
No full textThe use of hybrid nanomaterials, characterized by unprecedented behaviors and features, has paved the way toward promising applications in many fields, such as electrocatalysis, photocatalysis, electroanalysis, and environmental chemistry, impacting on the everyday life [1].
Suitably designed nanoheterojunctions enhance synergistic functionalities and allow one to obtain “brave new materials” with physicochemical properties that are not simply the addition of the precursors’ ones but are completely new, different, and unexpected. However, research on such systems is most often dominated by trial and error procedures, while a deep atomistic understanding of the phenomena inside of the junction region driving appropriate design of the final device is missing. Here, a concerted theoretical and electrochemical investigation is proposed to gain insights into the important class of heterojunctions made by metal-semiconductor interfaces.
This approach is applied to the case of silver/anatase hybrid nanocomposite, a very promising material for advanced sensing applications [2]. Specifically, it provided the first photorenewable sensor device, pushing the limits in terms of accuracy, sensitivity, detection limits, and photoactivity [3].
Considering that in most cases titania semiconductors are useless in electroanalysis and silver is subject to fouling and oxidation/passivation, such broad outcomes were totally unexpected. Despite the ongoing research, a quantitative and comprehensive understanding of the physics behind this nanocomposite is still missing, thus preventing its full exploitation and the extension of the same paradigm to other systems and devices.
In particular, we measure the exceptional electrochemical virtues of the Ag/TiO2 junction in terms of current densities and reproducibility, providing their explanation at the atomic-scale level and demonstrating how and why silver acts as a positive electrode [4]. Cyclic voltammetry and electrochemical impedance spectroscopy are used in combination with periodic plane-wave DFT calculations, giving comparable qualitative but also quantitative results. We theoretically estimate the overall amount of electron transfer toward the semiconductor side of the interface at equilibrium and suitably designed electrochemical experiments strictly agree with the theoretical charge transfer estimates. Moreover, photoelectrochemical measurements and theoretical predictions show the unique permanent charge separation occurring in the device, possible because of the synergy of Ag and TiO2, which exploits in a favorable band alignment, in a smaller electron–hole recombination rate and in a reduced carrier mobility when electrons cross the metal–semiconductor interface. Finally, the hybrid material is proven to be extremely robust against aging, showing complete regeneration, even after 1 year
[4].
References
[1] A.V. Emeline, V.N. Kuznetsov, V.K. Ryabchuk, N. Serpone, Environ. Sci. Pollut. Res. 19 (2012)
3666–3675.
[2] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst 140 (2015) 1486–1494.
[3] V. Pifferi, G. Soliveri, G. Panzarasa, G. Cappelletti, D. Meroni, L. Falciola, Anal. Bioanal. Chem. 408
(2016) 7339–7349.
[4] G. Di Liberto, V. Pifferi, L. Lo Presti, M. Ceotto, and L. Falciola, J. Phys. Chem. Lett. 8 (2017) 5372–
5377
Photo-renewable electroanalytical sensor for neurotransmitters detection: The role of silver ion nanoparticles
No full textA sandwich-like structure electrode of silver nanoparticles embedded in a titania (anatase polymorph) photoactive layer was prepared [1-2] and electrochemically characterized by cyclic voltammetry and electrochemical impedance spectroscopy.
In comparison with literature data on bare silver nanoparticles-modified electrodes [3-5], the new device features a pronounced electrocatalytic effect on the silver oxidation peak together with a great increase in the current intensity (Figure a).
Theoretical DFT calculations, performed using the VASP code [6], described the composite junction as a distorted bulk Ag structure, commensurate with the periodicity of the (101) face of the I41/amd TiO2 polymorph. The silver atoms close to the semiconductor were found to gain a partially positive charge [7], quickly decreasing with the distance from the TiO2 surface.
These joint theoretical and experimental studies demonstrated that the device could be considered as a “charged silver nanoparticles-based electrode”, with positively ionized surface silver atoms protected by the titania layer, which holds a partial negative charge. This peculiar electrode structure was found to be of a highly convenient use for sensor applications.
As a proof-of-concept, this device performed efficiently for the determination of neurotransmitters such as dopamine, norepinephrine and serotonin in simulated biological matrices (liquor, serum and urine). Moreover, this optimized analytical methodology is not only characterized by high sensitivity and low detection limits (around 0.03 μM, which makes it appealing for clinical purposes), but also by high selectivity in the presence of high concentrations of conventional interferents (uric and ascorbic acids). Furthermore, the fouling of the electrode surface, typical which is unavoidable for this kind of analytes, could be easily overcome by irradiating the device with UVA-light, which restored the initial sensor sensitivity. This feature allows the possibility to reactivate the sensor on site, i.e. directly in solution, to yield a system capable of working in continuous, able to be used in an integrated monitoring system.
References
[1] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst 140, 2015, pp 1486 – 1494.
[2] V. Pifferi, G. Soliveri, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, L. Falciola, RSC Advances 5, 2015, pp 71210 – 71214.
[3] O. S. Ivanova, F. P. Zamborini, J. Am. Chem. Soc. 132, 2010, pp 70–72.
[4] G. Chang, J. Zhang, M. Oyama, K. Hirao, J. Phys. Chem. B 109, 2005, pp 1204-1209.
[5] S.E. Ward Jones, F.W. Campbell, R. Baron, L. Xiao, R.G. Compton, J. Phys. Chem. C 112, 2008, pp 17820–17827.
[6] G. Kresse, D. Joubert, Phys. Rev. B: Condens. Matter 59, 1999, pp 1758−1775.
[7] W. Tang, E. Sanville, and G. Henkelman, J. Phys. Condens. Matter 2009, 21, 084204.
Acknowledgements
This work has been supported by Fondazione Cariplo (Milano, Italy), grant no. 2014-1285. We acknowledge the CINECA and the Regione Lombardia award under the LISA initiative (grant SURGREEN) for the availability of high performance computing resources. We also thank the Chemistry Department for funding through the Development Plan of Athenaeum grant – line B1 (UNIAGI 17777)
E-turism: Chinese and Western competition
No full textOver the last ten years (from 2008 to 2018), the global tourism market has been affected by several changes, which involved the main players of the sector.
In fact, new tourist consumers, with the highest expectations ever are growing in a market that is more and more aware of customer needs. Due to this, operators have been working on the definition of an innovative tourist offer.
The research presented in the paper aims to investigate and understand the role of the internet and new technologies in the development of the global tourism market, focusing on the approach of tourism operators in the major online platforms.
The method adopted is based on a comparison between China and the Western countries, these being considered the main markets in the tourism sector, both for outbound and inbound tourism. In particular, the research takes into account both Costumer and Online Travel Agencies (OTA) point of views. As far as Customer side, the focus is on the generations that are nowadays considered the most representative and the main focus for tourist market: Millennials and Generation Z. The behavior of the young customer is analyzed through a literature review; the behavior of the OTAs is deepened through an observation of their online approach in the period from 2008 to 2018.
Based on the results, the Western OTAs need to reorganize and implement new strategies to better catch the demand and to be more receptive to the international consumers, while the local T.Os need to find their own market position and keep up with trend opportunities
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