101,911 research outputs found
Traduzioni dal portoghese nelle "Navigationi et viaggi" di G. B. Ramusio. Una ricognizione
No full textArte de Furtar / Obras do diabinho da mão furada /D. Francisco Manuel de Melo / (presentazione e scelta antologica)
No full textOscillator strength and polarization of the forbidden n-->pi* band of trans-azobenzene. A computational study
No full textEfficient Heterogeneously Palladium-Catalysed Synthesis of Stilbenes and Bibenzyls
No full textCusati, Giuseppe Wedig, Anja Djakovitch, LaurentAn alternative heterogeneously palladium catalysed procedure for the synthesis of functional stilbenes and bibenzyls is reported. Starting from aryl bromides and using simple commercially available Pd/C catalyst at a low catalytic rate (1 mol%), stilbenes are obtained with 30-100% GC-yields and bibenzyls are produced in a one-pot fashion with 27-100% GC-yields. The procedure showed, however, some limitations when applied to strongly deactivated aryl bromides that could be in some extent overcome by using corresponding iodo derivatives
Theoretical Analysis of a 2D Metallic/Semiconducting Transition-Metal Dichalcogenide NbS2//WSe2 Hybrid Interface
No full textA first-principles theoretical study of a monolayer-thick lateral heterostructure (LH) joining two different transition metal dichalcogenides, NbS2 and WSe2, is reported. The NbS2//WSe2 LH can be considered a prototypical example of a metal (NbS2)/semiconductor (WSe2) 2D hybrid heterojunction. First, realistic atomistic models of the NbS2//WSe2 LH are generated and validated, its band structure is derived, and it is subjected to a fragment decomposition and electrostatic potential analysis to extract a simple but quantitative model of this interfacial system. Stoichiometric fluctuations models are also investigated and found not to alter the qualitative picture. Then, electron transport simulations are conducted and they are analyzed via band alignment analysis. It is concluded that the NbS2//WSe2 LH appears as a robust seamless in-plane 2D modular junction for potential use in optoelectronic devices going beyond the present miniaturization technology
Efficient Heterogeneously Palladium-Catalysed Synthesis of Stilbenes and Bibenzyls
No full textCusati, Giuseppe Wedig, Anja Djakovitch, LaurentAn alternative heterogeneously palladium catalysed procedure for the synthesis of functional stilbenes and bibenzyls is reported. Starting from aryl bromides and using simple commercially available Pd/C catalyst at a low catalytic rate (1 mol%), stilbenes are obtained with 30-100% GC-yields and bibenzyls are produced in a one-pot fashion with 27-100% GC-yields. The procedure showed, however, some limitations when applied to strongly deactivated aryl bromides that could be in some extent overcome by using corresponding iodo derivatives
Electronic Transport in 2D-Based Printed FETs from a Multiscale Perspective
No full textAs 2D materials (2DMs) gain the research limelight as a technological option for obtaining on-demand printed low-cost integrated circuits with reduced environmental impact, theoretical methods able to provide the necessary fabrication guidelines acquire fundamental importance. Here, a multiscale modeling technique is exploited to study electronic transport in devices consisting of a printed 2DM network of flakes. The approach implements a Monte Carlo scheme to generate the flake distribution. By means of ab initio density functional theory calculations together with non equilibrium Green's functions formalism, detailed physical insights on flake-to-flake transport mechanisms are provided. This later feeds a 3D drift-diffusion and Poisson solution to compute self-consistently transport and electrostatics in the device. The method is applied to MoS2 and graphene-based dielectrically gated FETs, highlighting the impact of the structure density and variability on the mobility and sheet resistance. The prediction capability of the proposed approach is validated against electrical measurements of in-house printed graphene conductive lines as a function of film thickness, demonstrating its strong potential as a guide for future experimental activity in the field
Photodynamics of azobenzene in a hindering environment
No full textWe have run trajectory surface hopping simulations of the trans-cis photoisomerization of azobenzene, subject to a pulling force. The model mimics two situations: a trans-azobenzene derivative with bulky substituents that may not be easily displaced, and a recent experiment by Gaub’s group [T. Hugel, N.B. Holland, A. Cattani, L. Moroder, M. Seitz, H.E. Gaub, Science 296 (2002) 1103; N.B. Holland, T. Hugel, G. Neuert, A. Cattani-Scholz, C. Renner, D. Oesterhelt, L. Moroder, M. Seitz, H.E. Gaub, Macromolecules 36 (2003) 2015; G. Neuert, T. Hugel, R.R. Netz, H.E. Gaub, Macromolecules 39 (2005) 789], in which a polymer with azobenzene units was stretched in an atomic force microscope. In both cases, the shortening of the azobenzene moiety in going from the trans to the cis form is opposed by a pulling force. Our simulations show that the trans-cis photoconversion is only partially suppressed by con- siderably large forces (500 pN or more). However, the cis isomer reverts to trans in the ground state, with the help of the pulling force and using the vibrational energy that is available in the first 1–2 ps. The lowering of the quantum yields is therefore the combined result of hindering of the excited state process and of the hot ground state back reaction
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