Search results for "2D"
showing 10 items of 305 documents
Few-layer Black Phosphorous Catalyzes Radical Additions to Alkenes Faster than Low-valence Metals
2020
Abstract The substitution of catalytic metals by p‐block main elements has a tremendous impact not only in the fundamentals but also in the economic and ecological fingerprint of organic reactions. Here we show that few‐layer black phosphorous (FL‐BP), a recently discovered and now readily available 2D material, catalyzes different radical additions to alkenes with an initial turnover frequency (TOF0) up to two orders of magnitude higher than representative state‐of‐the‐art metal complex catalysts at room temperature. The corresponding electron‐rich BP intercalation compound (BPIC) KP6 shows a nearly twice TOF0 increase with respect to FL‐BP. This increase in catalytic activity respect to t…
Proteīndisulfīdizomerāzes A17 izoformas strukturālie un funkcionālie pētījumi
2020
Bakalaura darba mērķis ir izpētīt PDI A17 (AGR2) izoformas strukturālās un funkcionālās īpašības, pro-onkogēno proteīndisulfīdu izomerāžu (PDI) selektīvo inhibitoru meklēšanas projekta ietvaros. Šīm nolūkam izstrādāt protokolu PDI A17 iegūšanai aktīvā formā, un piemērot proteīnu kodolu magnētiskās rezonanses (KMR) spektroskopijas pētīšanas metodei. Izpētīt saistību starp neaktivēto un aktivēto aziridīn-2-karbonskābes atvasinājumiem un PDI A17 izoformu. Šajā darbā aprakstīta optimizētas PDI A17 izoformas iegūšana, pamatoti izvēlētie apstākļi un metodes proteīna-ligandu saistības testēšanai ar 2D 1H-15N-HSQC eksperimenta palīdzību. Darbā arī ir aprakstīti pirmie rezultāti par aziridīn-2-karbo…
[Atrial fibrillation in patients with COVID-19. Usefulness of the CHA
2021
Resumen Introduccion y objetivos La enfermedad por coronavirus de 2019 (COVID-19) esta causada por el segundo coronavirus del sindrome respiratorio agudo y grave. La fibrilacion auricular (FA) es comun en situaciones agudas, en las que conlleva mas complicaciones y mortalidad. Metodos Analisis del Registro internacional HOPE (NCT04334291); el objetivo es evaluar la informacion pronostica de FA en pacientes con COVID-19. Se realizo un analisis multivariable y un emparejamiento por puntuacion de propension para evaluar la relacion entre FA y mortalidad. Ademas, se evaluo en estos pacientes el impacto en la mortalidad y los eventos embolicos de la puntuacion CHA2DS2-VASc. Resultados Entre los …
Inhomogeneous Broadening of Photoluminescence Spectra and Kinetics of Nanometer-Thick (Phenethylammonium)2PbI4 Perovskite Thin Films: Implications fo…
2021
An outstanding potentiality of layered two-dimensional (2D) organic–inorganic hybrid perovskites (2DHPs) is in the development of solar cells, photodetectors, and light-emitting diodes. In 2DHPs, an exciton is localized in an atomically thin lead(II) halide inorganic layer of sub-nanometer thickness as in a quantum well sandwiched between organic layers as energetic and dielectric barriers. In previous years, versatile optical characterization of 2DHPs has been carried out mainly for thin flakes of single crystals and ultrathin (of the order of 20 nm) polycrystalline films, whereas there is a lack of optical characterization of thick (hundreds of nanometers) polycrystalline films, fundament…
A 1D coupled Schrödinger drift-diffusion model including collisions
2005
We consider a one-dimensional coupled stationary Schroedinger drift-diffusion model for quantum semiconductor device simulations. The device domain is decomposed into a part with large quantum effects (quantum zone) and a part where quantum effects are negligible (classical zone). We give boundary conditions at the classic-quantum interface which are current preserving. Collisions within the quantum zone are introduced via a Pauli master equation. To illustrate the validity we apply the model to three resonant tunneling diodes.
Chapter 1 The Resolution Challenge in 3D Optical Microscopy
2009
Publisher Summary This chapter discusses the theoretical principles of 3D microscopy with the widespread realizations of 3D microscopy.Based on the paraxial diffraction equations, it has been shown that conventional microscopes, when dealing with 3D fluorescent samples, provide sets of 2D images. These images of the different transverse sections of the 3D object contain, in addition to the sharp image of the in focus section, the blurred images of the rest of the specimen. The paraxial formalism has been generalized in a very simple way to a non-paraxial context, showing that the equations that govern non-paraxial imaging are similar to those that govern paraxial imaging. The only differenc…
Toward Understanding Rich Superclusters
2008
We present a morphological study of the two richest superclusters from the 2dF Galaxy Redshift Survey (SCL126, the Sloan Great Wall, and SCL9, the Sculptor supercluster). We use Minkowski functionals, shapefinders, and galaxy group information to study the substructure of these superclusters as formed by different populations of galaxies. We compare the properties of grouped and isolated galaxies in the core region and in the outskirts of superclusters. The fourth Minkowski functional $V_3$ and the morphological signature $K_1$- $K_2$ show a crossover from low-density morphology (outskirts of supercluster) to high-density morphology (core of supercluster) at mass fraction $m_f \approx 0.7$.…
Plenty of motion at the bottom: atomically thin liquid gold membrane
2015
The discovery of graphene some ten years ago was the first proof of a free-standing two-dimensional (2D) solid phase. Here, using quantum molecular dynamics simulations of nanoscale gold patches suspended in graphene pores, we predict the existence of an atomically thin, free-standing 2D liquid phase. The liquid phase, enabled by the exceptional planar stability of gold due to relativistic effects, demonstrates extreme fluxionality of metal nanostructures and opens possibilities for a variety of nanoscale phenomena.
Effect of a Locally Repulsive Interaction on s-wave Superconductors
2016
The thermodynamic impact of the Coulomb repulsion on s-wave superconductors is analyzed via a rigorous study of equilibrium and ground states of the strong coupling BCS-Hubbard Hamiltonian. We show that the one-site electron repulsion can favor superconductivity at fixed chemical potential by increasing the critical temperature and/or the Cooper pair condensate density. If the one-site repulsion is not too large, a first or a second order superconducting phase transition can appear at low temperatures. The Meißner effect is shown to be rather generic but coexistence of superconducting and ferromagnetic phases is also shown to be feasible, for instance, near half-filling and at strong repul…
High-resolution study of some doubly excited vibrational states of PH2D: the m1 + m2, m2 + m5, m2 + m3, and m2 + m6 bands
2004
Abstract The absorption bands ν 1 + ν 2 , ν 2 + ν 3 , and ν 2 + ν 6 of PH 2 D have been recorded for the first time using a high-resolution Bruker 120 HR interferometer, and rotationally analyzed. Some transitions belonging to the very weak band ν 2 + ν 5 and enhanced in intensity by strong interactions with the ν 1 + ν 2 band were also assigned. Sets of parameters obtained from the fit reproduce experimental line position of the bands ν 1 + ν 2 and ν 2 + ν 3 with about the experimental accuracy. The residuals of the ro-vibrational energies of the ν 2 + ν 6 band are about 10 times larger. Reasons for the poorer reproduction of the latter data are given.