Search results for "molecular"
showing 10 items of 32340 documents
Supplementary material 4 from: Vecchi M, Stec D (2021) Integrative descriptions of two new Macrobiotus species (Tardigrada, Eutardigrada, Macrobiotid…
2021
Partitions and models selection results
Supplementary material 3 from: Vecchi M, Stec D (2021) Integrative descriptions of two new Macrobiotus species (Tardigrada, Eutardigrada, Macrobiotid…
2021
Thorpe normalization calculations and results
Temperature-dependent mutational robustness can explain faster molecular evolution at warm temperatures, affecting speciation rate and global pattern…
2016
Distribution of species across the Earth shows strong latitudinal and altitudinal gradients with the number of species decreasing with declining temperatures. While these patterns have been recognized for well over a century, the mechanisms generating and maintaining them have remained elusive. Here, we propose a mechanistic explanation for temperature-dependent rates of molecular evolution that can influence speciation rates and global biodiversity gradients. Our hypothesis is based on the effects of temperature and temperature-adaptation on stability of proteins and other catalytic biomolecules. First, due to the nature of physical forces between biomolecules and water, stability of biomo…
Pd2Au36(SR)(24) cluster: structure studies
2015
The location of the Pd atoms in Pd2Au36(SC2H4Ph)(24), is studied both experimentally and theoretically. X-ray photoelectron spectroscopy (XPS) indicates oxidized Pd atoms. Palladium K-edge extended X-ray absorption fine-structure (EXAFS) data clearly show Pd-S bonds, which is supported by far infrared spectroscopy and by comparing theoretical EXAFS spectra in R space and circular dichroism spectra of the staple, surface and core doped structures with experimental spectra.
Octopus, a computational framework for exploring light-driven phenomena and quantum dynamics in extended and finite systems
2020
Over the last few years, extraordinary advances in experimental and theoretical tools have allowed us to monitor and control matter at short time and atomic scales with a high degree of precision. An appealing and challenging route toward engineering materials with tailored properties is to find ways to design or selectively manipulate materials, especially at the quantum level. To this end, having a state-of-the-art ab initio computer simulation tool that enables a reliable and accurate simulation of light-induced changes in the physical and chemical properties of complex systems is of utmost importance. The first principles real-space-based Octopus project was born with that idea in mind,…
Trapped Ion Oscillation Frequencies as Sensors for Spectroscopy
2010
The oscillation frequencies of charged particles in a Penning trap can serve as sensors for spectroscopy when additional field components are introduced to the magnetic and electric fields used for confinement. The presence of so-called "magnetic bottles" and specific electric anharmonicities creates calculable energy-dependences of the oscillation frequencies in the radiofrequency domain which may be used to detect the absorption or emission of photons both in the microwave and optical frequency domains. The precise electronic measurement of these oscillation frequencies therefore represents an optical sensor for spectroscopy. We discuss possible applications for precision laser and microw…
Realization of time-resolved two-vacuum-ultraviolet-photon ionization
2009
International audience; Ultrafast dynamics of excited molecules is studied through time-resolved two-vacuum-ultraviolet (vuv)- photon ionization using a nonlinear volume autocorrelator unit. The two-vuv-photon process is induced by the intense fifth harmonic radiation of a femtosecond Ti:sapphire laser. In a proof-of-principle experiment, ultrafast dynamics of excited ethylene and oxygen molecules are investigated. Molecular decay times are deduced by comparing the experimental data with the results of a numerical model that accounts for the spatial and temporal characteristics of the harmonic field. The present experiments pave a convenient way for time domain investigations in the vuv-xuv s…
Understanding the Interactions of Guanine Quadruplexes with Peptides as Novel Strategies for Diagnosis or Tuning Biological Functions
2023
Guanine quadruplexes (G4s) are nucleic acid structures exhibiting a complex structural behavior and exerting crucial biological functions, in both cells and viruses. The specific interactions of peptides with G4s, as well as the understanding of the factors driving the specific recognition, are important for the rational design of both therapeutic and diagnostic agents. In the present minireview, we examine the most important studies dealing with the interactions between G4s and peptides, highlighting the strengths and limitations of the present analytic approaches. We also show how the combined use of high-level molecular simulation techniques and experimental spectroscopy represents the b…
Tin resonance-ionization schemes for atomic- And nuclear-structure studies
2020
This paper presents high-precision spectroscopic measurements of atomic tin using five different resonance-ionization schemes performed with the collinear resonance-ionization spectroscopy technique. Isotope shifts were measured for the stable tin isotopes from the $5{s}^{2}5{p}^{2}\phantom{\rule{0.28em}{0ex}}^{3}{P}_{0,1,2}$ and ${}^{1}{S}_{0}$ to the $5{s}^{2}5p6s\phantom{\rule{0.28em}{0ex}}^{1}{P}_{1},^{3}{P}_{1,2}$ and $5{s}^{2}5p7s{\phantom{\rule{0.28em}{0ex}}}^{1}{P}_{1}$ atomic levels. The magnetic dipole hyperfine constants ${A}_{\mathrm{hf}}$ have been extracted for six atomic levels with electron angular momentum $Jg0$ from the hyperfine structures of nuclear spin $I=1/2$ tin isot…
Theoretical study of systems with interest in molecular magnetism and electronics
2013
The project described in this thesis is motivated by a particular interest in Molecular Magnetism from a theoretical point of view. Molecular Magnetism, is still a thriving research field where some problems remain unexplored: A large amount of molecular systems are still theoretically unmanageable due to their huge computational requirements, while the standard software package cannot profit from the power of multiprocessor supercomputers. The scientific community would require a computational code to calculate the magnetic properties of mixed-valence clusters. A new magnetic POM, which needs only one magnetic ion to behave as SMMs, has appeared. A rationalization of its behaviour and an e…