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Nonlocal van der Waals Approach Merged with Double-Hybrid Density Functionals: Toward the Accurate Treatment of Noncovalent Interactions
2015
Noncovalent interactions drive the self-assembly of weakly interacting molecular systems to form supramolecular aggregates, which play a major role in nanotechnology and biochemistry. In this work, we present a thorough assessment of the performance of different double-hybrid density functionals (PBE0-DH-NL, revPBE0-DH-NL, B2PLYP-NL, and TPSS0-DH-NL), as well as their parent hybrid and (meta)GGA functionals, in combination with the most modern version of the nonlocal (NL) van der Waals correction. It is shown that this nonlocal correction can be successfully coupled with double-hybrid density functionals thanks to the short-range attenuation parameter b, which has been optimized against ref…
New insights for materials science characterisation using different complementary techniques combined with X-ray absorption Spectroscopy
2005
The combination of x-ray absorption spectroscopy (XAS) with UV-Vis and Raman spectroscopies or with Differential Scanning Calorimetry (DSC) has been recently carried out on the D44 beamline of DCI-LURE. The different set-ups used to perform such combinations are described and examples of combined investigations belonging to different field of materials science (coordination chemistry, sol-gel and catalysis) are presented.
Oxotris(oxalato)niobate(V) as counterion in cobalt(II) spin-crossover systems
2016
Abstract This work is devoted to the investigation of the thermally induced spin-crossover behavior from a high-spin state (HS, S = 3/2) at higher temperatures to a low-spin phase (LS, S = 1/2) at lower temperatures of the six-coordinate cobalt(II) complex in the compound [Co(terpy)2]3[NbO(C2O4)3]2·3CH3OH·4H2O (2). The crystal structure of 2 together with that of its counterion as tetraphenylarsonium(V) salt (AsPh4)3[NbO(C2O4)3]·9H2O (1) are also included. The spin-crossover process was followed by the thermal variation of the χMT product between 2.0 and 400 K under the warming mode, with the LS configuration being achieved at T ⩽ 200 K and the LS → HS interconversion being incomplete at 4…
Lithium intercalation chemistry, microstructure and superconductivity in zirconium and hafnium nitride halides
2000
Abstract Lithium intercalation in β-MNX (M=Zr, Hf; X=Cl, Br) leads to superconducting compounds with critical temperatures between 12 and 24 K. The lithium uptakes after treatment of the host materials with n-butyllithium/hexane solutions are ca. 0.2 atoms per formula for β-ZrNCl and β-ZrNBr, and between 0.07 and 0.67 for β-HfNCl. Electrochemical lithiation experiments agree with the results obtained with chemical methods, as samples with larger capacity on discharge are also those having larger lithium contents after chemical lithiation. Variations exist in the electrochemical profiles of different batches for the three compounds indicating differences in the intercalation reaction pathway…
Sorting of Enhanced Reference Raman Spectra of a Single Amino Acid Molecule
2014
In this contribution, we report the identification of the principal reference Raman spectra of a single cystein molecule. To that purpose, we design an active Surface Enhanced Raman Spectroscopy (SERS) template based on surfactant-less Chebyshev nanoparticles operating in a microfluidic platform. A principal component analysis is obtained from fluctuating spectra to sort the reference spectra of cystein. The assignment of Raman bands brings new insight into the conformation of an amino acid adsorbed onto gold nanoparticle.
Spectroscopic behaviour of metal–drug complexes. Infrared spectra of Cu(II) complexes with 5-amino-1,3,4-thiadiazole-2-thiol (Hatm)
1997
Abstract The infrared spectra of the drug Hatm and its copper (II) complexes with stoichiometry [Cu(atm) 2 (H 2 O)] and [Cu(Hatm)(HIm) 2 (SO 4 )] are reported and discussed. The Raman spectrum of Hatm is also reported. An assignment of Hatm, HIm, H 2 O and SO 4 modes in the complexes is proposed in comparison with the modes of the free ligands. Important information about the metal–ligand vibrations has been obtained.
Fluorescence and color as markers for the Maillard reaction in milk–cereal based infant foods during storage
2007
Abstract Free and total fluorescence compounds and color formation were measured in three different milk–cereal based infant foods stored at 25, 30 and 37 °C for 9 months to evaluate the advanced and final stages of the Maillard reaction. Milk–cereal infant foods containing honey (B) or fruits (C) had fluorescent values higher than sample (A) without them. This difference could be ascribed to the higher monosaccharide (fructose and/or glucose) content of (B) and (C), which could increase susceptibility to the Maillard reaction. However, for color increase (ΔE), no significant differences (p
The Nonlocal Correlation Density Functional VV10
2015
Abstract In this chapter, we review the most relevant attempts to merge the Vydrov and van Voorhis nonlocal density-dependent functional kernel (VV10) with modern density functionals to accurately describe van der Waals interactions with a reasonable computational cost. The chapter is organized by providing first an introduction of the relevance of van der Waals interactions and the difficulties of common density functionals to describe these forces. Second, the historical developments that eventually give rise to the most modern formulation of the nonlocal density functional VV10 are briefly addressed. Then, an overview of its technical formulation, adjustable parameters, and implementatio…
Intrinsic Viscosities of Polyelectrolytes: Determination and Modeling of the Effects of Extra Salt
2011
Based on early measurements of J. J. Hermans and co-workers (D. T. F. Pals, J. J. Hermans, Recl. Trav. Chim. Pays-Bas 1952, 71, 513-520; D. T. F. Pals, J. J. Hermans, J. Polym. Sci. 1950, 5, 733-734; D. T. F. Pals, J. J. Hermans, J. Polym. Sci. 1948, 3, 897-898), the present contribution demonstrates how primary data should be evaluated in order to obtain reliable intrinsic viscosities. This procedure yields detailed information on the changes of the intrinsic viscosities and of the corresponding viscometric interaction parameters caused by an increasing salinity of water. Both quantities decline from a maximum value in the pure solvent to a minimum value, which is approached in the limit o…
Effect of pulsed electric field on Maillard reaction and hydroxymethylfurfural production
2020
Abstract As an emerging nonthermal processing technology, the application of pulsed electric field (PEF) has received increasing attention not only for its capability to inactivate enzymes and microorganisms or to enhance mass transfer during the extraction process but also for its potential to inhibit the formation of chemical contaminants during processing, such as the formation of hydroxymethylfurfural (HMF). HMF is a potential carcinogen to humans that can be produced via the Maillard reaction (MR). Compared with thermal treatment, PEF can minimize the extent of MR, reducing the contents of HMF. However, in some cases, MR and HMR may be promoted, closely associated with PEF conditions a…