Novel Tetrazine Organometallic Complexes for Nonlinear Optical Switching: a Combined Density Functional Theory and Experimental Study

Over the past decade, mono- and bi- and oligonuclear organometallic complexes have been deal of great interest by material chemists and engineers due to their remarkable nonlinear optical (NLO), magnetic and electric properties. [1] They were furthermore envisaged as powerful candidates for quantum computing, molecular devices and more interestingly as molecular switches. The definition of molecular switch implies that a compound should have two interconvertable stable forms that have a significant difference in the magnitude of, at least, one of their physico-chemical properties. [2] In the case of organometallic complexes the most expedite way to achieve such interconversion is by redox means, where one takes advantage of the different oxidations states allowed by a single or multiple metal centers that interact with each other, and with the ligands therein. It is known that the choice of an appropriate π-bridging system between the metal centers is crucial to obtain the adequate electronic environment for efficient metal-to-metal and metal-to-ligand interactions, and hence fine tune the optical, electric and magnetic macroscopic properties. Mixed-valance metal complexes from group VIII, particular Fe(II)/Fe(III) and Ru(II)/Ru(III) systems [3,4], have been successfully synthesized as stable species that possess strong metal-to-ligand charge transfer (MLCT) and inter-valence charge transfer (IVCT) absorption bands in visible and NIR regions, respectively.[5, 6] This is the case of the well known Creutz-Taube ion [(H3N)5Ru(m-pz)Ru(NH3)5]5+ (pz=pyrazine) and related compounds. Substituted 1,2,4,5-tetrazine (tz) strongly enhance both the stability and the MLCT and IVCT phenomenon’s since they act as a strong π-acceptor and can stimulate the metal-to-metal interaction. [6] In this work, we present our ongoing studies in the use of substituted 1,2,4,5-tetrazine (tz) ligands as the π-bridge between two transition metal centers, both experimentally and by means of Density Functional Theory (DFT). Synthesis and characterization by NMR, voltammetric and UV-Vis. spectra are presented. The DFT calculations were used to evaluate the nature of the electronic transitions as well as the switching of the NLO properties. The compounds showed to be great candidates for NLO switching since the magnitude of such property can change upon redox stimulus at the metal centers

Social-aware Forwarding in Opportunistic Wireless Networks: Content Awareness or Obliviousness?

With the current host-based Internet architecture, networking faces limitations in dynamic scenarios, due mostly to host mobility. The ICN paradigm mitigates such problems by releasing the need to have an end-to-end transport session established during the life time of the data transfer. Moreover, the ICN concept solves the mismatch between the Internet architecture and the way users would like to use it: currently a user needs to know the topological location of the hosts involved in the communication when he/she just wants to get the data, independently of its location. Most of the research efforts aim to come up with a stable ICN architecture in fixed networks, with few examples in ad-hoc and vehicular networks. However, the Internet is becoming more pervasive with powerful personal mobile devices that allow users to form dynamic networks in which content may be exchanged at all times and with low cost. Such pervasive wireless networks suffer with different levels of disruption given user mobility, physical obstacles, lack of cooperation, intermittent connectivity, among others. This paper discusses the combination of content knowledge (e.g., type and interested parties) and social awareness within opportunistic networking as to drive the deployment of ICN solutions in disruptive networking scenarios. With this goal in mind, we go over few examples of social-aware content-based opportunistic networking proposals that consider social awareness to allow content dissemination independently of the level of network disruption. To show how much content knowledge can improve social-based solutions, we illustrate by means of simulation some content-oblivious/oriented proposals in scenarios based on synthetic mobility patterns and real human traces.Comment: 7 pages, 6 figure

The disposition effect among mutual fund participants : a re- examination

Using information on mutual fund trades executed from 1998 to 2017 by 31,513 individual investor clients of a major Portuguese financial institution, we study the relationship between the disposition effect, financial literacy and trading experience. We find that mutual fund investors exhibit strong disposition effect. The tendency to hold losers is partially offset with literacy: not only holding a university degree reduces the propensity to hold on to loser funds but also higher financial knowledge and stronger math skills reduce the disposition effect. Literacy also plays a role in shaping the way experience affects this bias. Evidence of the disposition effect persists after accounting for redemption fees, bad emotions, irrational beliefs, market sentiment and the existence of someone to blame.info:eu-repo/semantics/publishedVersio

Contagion effects of the US Subprime Crisis on Developed Countries

This study assesses whether capital markets of developed countries reflect the effects of financial contagion from the US subprime crisis and, in such case, if the intensity of contagion differs across countries. Adopting a definition of contagion that relates the phenomenon to an increase of cross-market linkages following a shock, copula models are used to analyse how the connections between the US and each market in the sample, evolved from the pre-crisis to the crisis period. The results suggest that markets in Canada, Japan, Italy, France and the United Kingdom display significant levels of contagion, which are less relevant in Germany. Canada appears to be the country where the highest intensity of contagion is observed.G7, subprime crisis, contagion, copula, event study.

ALFRED-DONAT AGACHE URBAN PROPOSAL FOR COSTA DO SOL. FROM THE TERRITORY TO THE CITY.

This paper reviews the development of Costa do Sol, as planned by architect urbanist Alfred-Donat Agache, for Lisbon Region in Portugal. The Plano Expansão Região Oeste de Lisboa (1934-1936) prepared by Agache and requested by Portuguese Minister of Public Works, Duarte Pacheco will be analyzed. This paper aims also to identify the principles and the theoretical foundations that have determined Agache urban vision for Lisbon City and its Territory. Finally, this paper aims to demonstrate that Alfred-Donat Agache methodological framework has applied Frederick Le Play socio-economic scientific approach. Such approach has informed the construction of a ‘civic’ urbanism that will be identified and analyzed. Two main goals seem to have guided Agache work at Costa do Sol: (i) the fully urban analysis of the city, throughout its social, economic, geographic and urban conditions (past and present) and (ii) the need to expose such analysis to the city’s inhabitants. Finally, this paper demonstrates Costa do Sol proposal to testify a comprehensive understanding of three distinct scales: (i) the territory; (ii) the city; (iii) but also the urban form. The acknowledgment of Agache ‘civic’ urban vision requests a public divulgation to allow the building of Good Practice Lessons for contemporary urban planning theory and practice

ALFRED-DONAT AGACHE URBAN PROPOSAL FOR COSTA DO SOL. FROM THE TERRITORY TO THE CITY.

This paper reviews the development of Costa do Sol, as planned by architect urbanist Alfred-Donat Agache, for Lisbon Region in Portugal. The Plano Expansão Região Oeste de Lisboa (1934-1936) prepared by Agache and requested by Portuguese Minister of Public Works, Duarte Pacheco will be analyzed. This paper aims also to identify the principles and the theoretical foundations that have determined Agache urban vision for Lisbon City and its Territory. Finally, this paper aims to demonstrate that Alfred-Donat Agache methodological framework has applied Frederick Le Play socio-economic scientific approach. Such approach has informed the construction of a ‘civic’ urbanism that will be identified and analyzed. Two main goals seem to have guided Agache work at Costa do Sol: (i) the fully urban analysis of the city, throughout its social, economic, geographic and urban conditions (past and present) and (ii) the need to expose such analysis to the city’s inhabitants. Finally, this paper demonstrates Costa do Sol proposal to testify a comprehensive understanding of three distinct scales: (i) the territory; (ii) the city; (iii) but also the urban form. The acknowledgment of Agache ‘civic’ urban vision requests a public divulgation to allow the building of Good Practice Lessons for contemporary urban planning theory and practice