Atomistic Simulations of P(NDI2OD-T2) Morphologies: From Single Chain to Condensed Phases

We investigate theoretically the structure, crystallinity, and solubility of a high-mobility n-type semiconducting copolymer, P(NDI2OD-T2), and we propose a set of new force field parameters. The force field is reparametrized against density functional theory (DFT) calculations, with the aim to reproduce the correct torsional angles that govern the polymer chain flexibility and morphology. We simulate P(NDI2OD-T2) oligomers in different environments, namely, in vacuo, in the bulk phase, and in liquid toluene and chloronaphthalene solution. The choice of these solvents is motivated by the fact that they induce different kinds of molecular preaggregates during the casting procedures, resulting in variable device performances. Our results are in good agreement with the available experimental data; the polymer bulk structure, in which the chains are quite planar, is correcly reproduced, yet the isolated chains are flexible enough to fold in vacuo. We also calculate the solubility of P(NDI2OD-T2) in toluene and chloronaphthalene, predicting a much better solubility of the polymer in the latter, also in accordance to experimental observations. Different morphologies and dynamics of the oligomers in the two solvents have been observed. The proposed parameters make it possible to obtain the description of P(NDI2OD-T2) in different environments and can serve as a basis for extensive studies of this polymer semiconductor, such as, for example, the dynamics of aggregation in solvent

Planning smart cities. Comparison of two quantitative multicriteria methods applied to real case studies

Today, cities are facing many challenges such as pollution, resource consumption, gas emissions and social inequality. Many future city views have been developed to solve these issues such as the Smart City model. In literature several methods have been proposed to plan a Smart city, but, at the best of the authors’ knowledge, only a few of them have been really applied to the urban context. Most of them are indeed theoretical and qualitative approaches, providing scenarios that have not been applied to real cities/districts. Moreover, a comparison among the results of different quantitative planning models applied to real case studies is still missing. In this framework, the aim of the paper is to propose a new quantitative method based on a previous qualitative model developed by the same authors. The feasibility and validity of the method will be tested through the comparison with an existing AHP model and the application of both approaches on two real case studies, characterized by different territorial levels. Results of the analysis show that both methods are consistent, reliable and do provide similar results despite the differences in the application process

Fundamentals of tin iodide perovskites:A promising route to highly efficient, lead-free solar cells

Hybrid tin-iodide perovskites are investigated as potential lead-free replacement of the lead-iodide perovskites; however, the intrinsic operational limit of these systems has not been described in detail, so far. In this work we combine advanced ab initio calculations with XRD and absorption measurements to lay out the fundamentals of formamidinium (FASnI3) and methylammonium (MASnI3) tin iodide perovskites, in comparison with the lead-halide MAPbI3 prototype. Our theoretical analysis reveals that the tin-based materials display an intrinsic photoconversion efficiency on a par with the lead perovskites, and even superior in the thick-layer limit, where the theoretical PCE reaches 30.5% for lead-halides, and 32.3% for tin-halides under AM1.5G illumination; this is the result of two competing factors: a smaller absorption cross section at the onset for stannates, and their smaller band gap of 1.36 eV, thus very close to the ideal Shockley-Queisser limit. We found the rate of photoluminescence emission extremely sensitive to the absorption spectral weight at the band extrema, resulting in B-factor as different as 7.6 × 10-9 s-1 cm3 for MASnI3 and 0.4 × 10-10 s-1 cm3 for FASnI3. The additional impact of Urbach energy and hole doping, giving rise to large Burstein-Moss effect, is described in detail. This journal i

Prevention of Breast cancer with tamoxifen:preliminary findings from the italian randomised trial among hysterectomised women

Prevention of breast cancer with tamoxifen: preliminary findings from the Italian randomised trial among hysterectomised women. Italian Tamoxifen Prevention Study. Veronesi U, Maisonneuve P, Costa A, Sacchini V, Maltoni C, Robertson C, Rotmensz N, Boyle P. SourceEuropean Institute of Oncology, Milan, Italy. Abstract BACKGROUND: Tamoxifen is a candidate chemopreventive agent in breast cancer, although the drug may be associated with the development of endometrial cancer. Therefore we did a trial in hysterectomised women of tamoxifen as a chemopreventive. METHODS: In October, 1992, we started a double-blind placebo-controlled, randomised trial of tamoxifen in women (mainly in Italy) who did not have breast cancer and who had had a hysterectomy. Women were randomised to receive tamoxifen 20 mg per day or placebo, both orally for 5 years. The original plan was to follow the intervention phase by 5 years' follow-up. In June, 1997, the trialists and the data-monitoring committee decided to end recruitment primarily because of the number of women dropping out of the study. Recruitment ended on July 11, 1997, and the study will continue as planned. The primary endpoints are the occurrence of and deaths from breast cancer. This preliminary interim analysis is based on intention-to-treat. FINDINGS: 5408 women were randomised; participating women have a median follow-up of 46 months for major endpoints. 41 cases of breast cancer occurred so far; there have been no deaths from breast cancer. There is no difference in breast-cancer frequency between the placebo (22 cases) and tamoxifen (19) arms. There is a statistically significant reduction of breast cancer among women receiving tamoxifen who also used hormone-replacement therapy during the trial: among 390 women on such therapy and allocated to placebo, we found eight cases of breast cancer compared with one case among 362 women allocated to tamoxifen. Compared with the placebo group, there was a significantly increased risk of vascular events and hypertriglyceridaemia among women on tamoxifen. INTERPRETATION: Although this preliminary analysis has low power, in this cohort of women at low-to-normal risk of breast cancer, the postulated protective effects of tamoxifen are not yet apparent. Women using hormone-replacement therapy appear to have benefited from use of tamoxifen. There were no deaths from breast cancer recorded in women in the study. It is essential to continue follow-up to quantify the long-term risks and benefits of tamoxifen therapy

15 years of protest and media technologies scholarship: A sociotechnical timeline

This article investigates the relationship between the invention of new media technologies and scholarship concerning protest and political engagement. Building on an innovative approach that moves beyond a systematic literature review, this article contributes to our understanding of scholarship concerning digital communication technologies and how they may have been adopted and shaped protest movements and political engagement. Based on visualizations, we draw a sociotechnical timeline of protest and media technology scholarship within three dimensions: technological development, methods and techniques, and the social phenomena under investigation. The article concludes by identifying major trends in protest and media technologies scholarship over the past 15 years. The sociotechnical timeline enhances our understanding of academic discourse at the intersection of protest and media technologies by highlighting shortcomings and potential for future research

Mean Field Theory of Josephson Junction Arrays with Charge Frustration

Using the path integral approach, we provide an explicit derivation of the equation for the phase boundary for quantum Josephson junction arrays with offset charges and non-diagonal capacitance matrix. For the model with nearest neighbor capacitance matrix and uniform offset charge $q/2e=1/2$, we determine, in the low critical temperature expansion, the most relevant contributions to the equation for the phase boundary. We explicitly construct the charge distributions on the lattice corresponding to the lowest energies. We find a reentrant behavior even with a short ranged interaction. A merit of the path integral approach is that it allows to provide an elegant derivation of the Ginzburg-Landau free energy for a general model with charge frustration and non-diagonal capacitance matrix. The partition function factorizes as a product of a topological term, depending only on a set of integers, and a non-topological one, which is explicitly evaluated.Comment: LaTex, 24 pages, 8 figure

Magnetic trapping of ultracold neutrons

Three-dimensional magnetic confinement of neutrons is reported. Neutrons are loaded into an Ioffe-type superconducting magnetic trap through inelastic scattering of cold neutrons with 4He. Scattered neutrons with sufficiently low energy and in the appropriate spin state are confined by the magnetic field until they decay. The electron resulting from neutron decay produces scintillations in the liquid helium bath that results in a pulse of extreme ultraviolet light. This light is frequency downconverted to the visible and detected. Results are presented in which 500 +/- 155 neutrons are magnetically trapped in each loading cycle, consistent with theoretical predictions. The lifetime of the observed signal, 660 s +290/-170 s, is consistent with the neutron beta-decay lifetime.Comment: 17 pages, 18 figures, accepted for publication in Physical Review

Activism and radical politics in the digital age: Towards a typology

This article aims to develop a typology for evaluating different types of activism in the digital age, based on the ideal of radical democracy. Departing from this ideal, activism is approached in terms of processes of identification by establishing conflictual frontiers to outside Others as either adversaries or enemies. On the basis of these discussions, we outline a typology of four kinds of activists: the salon activist, the contentious activist, the law-abiding activist, and the Gandhian activist. The typology’s first axis, between antagonism and agonism, is derived from normative discussions in radical democracy concerning developing frontiers. The second axis, about readiness to engage in civil disobedience, is derived from a review of studies of different forms of online activism. The article concludes by suggesting that the different forms of political engagement online have to be taken into account when studying how online activism can contribute to social change

The democratic interface: technology, political organization, and diverging patterns of electoral representation

Democracies are experiencing historic disruptions affecting how people engage with core institutions such as the press, civil society organizations, parties, and elections. These processes of citizen interaction with institutions operate as a democratic interface shaping self-government and the quality of public life. The electoral dimension of the interface is important, as its operation can affect all others. This analysis explores a growing left-right imbalance in the electoral connection between citizens, parties, elections, and government. This imbalance is due, in part, to divergent left-right preferences for political engagement, organization, and communication. Support on the right for clearer social rules and simpler moral, racial and nationalist agendas are compatible with hierarchical, leader-centered party organizations that compete more effectively in elections. Parties on the left currently face greater challenges engaging citizens due to the popular meta-ideology of diversity and inclusiveness and demands for direct or deliberative democracy. What we term connective parties are developing technologies to perform core organizational functions, and some have achieved electoral success. However, when connective parties on the left try to develop shared authority processes, online and offline, they face significant challenges competing with more conventionally organized parties on the right