Vibrational and dielectric properties of the bulk transition metal dichalcogenides

Interest in the bulk transition metal dichalcogenides for their electronic, photovoltaic, and optical properties has grown and led to their use in many technological applications. We present a systematic investigation of their interlinked vibrational and dielectric properties, using density functional theory and density functional perturbation theory, studying the effects of the spin-orbit interaction and of the long-range e$^-$- e$^-$ correlation as part of our investigation. This study confirms that the spin-orbit interaction plays a small role in these physical properties, while the direct contribution of dispersion corrections is of crucial importance in the description of the interatomic force constants. Here, our analysis of the structural and vibrational properties, including the Raman spectra, compare well to experimental measurement. Three materials with different point groups are showcased and data trends on the full set of fifteen existing hexagonal, trigonal, and triclinic materials are demonstrated. This overall picture will enable the modeling of devices composed of these materials for novel applications.Comment: 11 pages, 6 figure

Vibrational and dielectric properties of monolayer transition metal dichalcogenides

First-principles studies of two-dimensional transition metal dichalcogenides have contributed considerably to the understanding of their dielectric, optical, elastic, and vibrational properties. The majority of works to date focus on a single material or physical property. Here we use a single first-principles methodology on the whole family of systems, to investigate in depth the relationships between different physical properties, the underlying symmetry and the composition of these materials, and observe trends. We compare to bulk counterparts to show strong interlayer effects in triclinic compounds. Previously unobserved relationships between these monolayer compounds become apparent. These trends can then be exploited by the materials science, nanoscience, and chemistry communities to better design devices and heterostructures for specific functionalities.Comment: 4 figures, 11 page

Composition change-driven texturing and doping in solution-processed SnSe thermoelectric thin films

The discovery of SnSe single crystals with record high thermoelectric efficiency along the b-axis has led to the search for ways to synthesize polycrystalline SnSe with similar efficiencies. However, due to weak texturing and difficulties in doping, such high thermoelectric efficiencies have not been realized in polycrystals or thin films. Here, we show that highly textured and hole doped SnSe thin films with thermoelectric power factors at the single crystal level can be prepared by solution process. Purification step in the synthetic process produced a SnSe-based chalcogenidometallate precursor, which decomposes to form the SnSe2 phase. We show that the strong textures of the thin films in the b???c plane originate from the transition of two dimensional SnSe2 to SnSe. This composition change-driven transition offers wide control over composition and doping of the thin films. Our optimum SnSe thin films exhibit a thermoelectric power factor of 4.27 ??W cm???1 K???2

Room I, 10/16/2000 2: 00 PM - 4: 00 PM (PS) Evaluation of Intubating Conditions and Safety Following Rapacuronium, Succinylcholine or Placebo during Anesthesia with Alfentanil and Propofol

peer reviewe

Étude des cibles génétiques avec des mutagènes marqués. Action du Myleran sur la résistance à la streptomycine de Chlamydomonas eugametos.

peer reviewedCells of Chlamydomonas eugametos Moewus, sex minus, were treated with tritiated myleran and a correlation was established between the mutation frequency (loss of resistance to streptomycin) and the tritium content of the isolated DNA. It was concluded that the resistance to streptomycin is due to a single DNA locus per cell; this is particularly interesting in view of the fact that these algae cells are haploid. It has been supposed that the observed mutations were due nearly exclusively to the cross-linking of the complementary strands of the DNA molecule carrying the competent locus. The size of this DNA molecule was provisionally calculated to be 3,600,000 or 2,900,000 a.m.u.;† these results are derived from two separate sets of experiments. © 1963, Academic Press Inc. (London) Ltd.. All rights reserved

Panel 3: political consultancy: an area for information systems academicians to create value?

Information Systems are increasingly a topic of, and underlie, the implementation of most government policies. As such they would seem to provide an enormous opportunity for IS academicians to provide 'political consultancy' and to offer their expertise in relation to political decision making. Throughout Europe and around the world, issues such as data privacy, online gaming, the protection of youth, net neutrality, media competency, public health ICT, ICT-based citizen services, digital divide, encryption versus transparency, and the social, competitive, and political impacts of phenomena such as Google, Facebook, and Twitter are being considered by policy makers; and each of these requires careful understanding of information systems issues. However, the contributions of IS academicians to political decision making come across as minor compared to our colleagues in the fields of law, political science, or economics. In the panel, we will explore the pros and cons of senior and junior IS academicians getting involved in these activities from an individual's, a school's, and a community's perspective. Panelists will share their experiences with political consultancy and hope to intensively discuss with the audience, mainly along their interests, ideas, and counter-positions