Search results for "Spectroscopy"

Thermal vibration analysis of two organic phosphates. Comparison with far-IR spectra

2002

Analytical chemistry on many-center chiral compounds based on vibrational circular dichroism: Absolute configuration assignments and determination of…

2019

The absolute configuration of a chiral molecule is key to its biological activity. Being able to find out what this configuration is, is thus crucial for a wide range of applications. The difficulties associated with such a determination steeply rise as the number of chiral centers in a given compound becomes larger. Concurrently, it becomes increasingly more challenging to determine the levels and identity of potential stereochemical contaminants in a given sample with one and the same technique, leading in practice to extensive and laborious efforts employing multiple analytical techniques. Here, experimental and theoretical studies based on Vibrational Circular Dichroism (VCD) are presen…

The lineshape of the electronic spectrum of the green fluorescent protein chromophore, part I: gas phase.

2014

The vibronic spectra of the green fluorescent protein chromophore analogues p-hydroxybenzylidene-2,3-dimethylimidazolinone (HBDI) and 3,5-tert-butyl-HBDI (35Bu) are similar in the vacuum, but very different in water or ethanol. To understand this difference, we have computed the vibrationally resolved solution spectra of these chromophores, using the polarizable continuum model (PCM) to account for solvent effects on the (harmonic) potential energy surfaces (PES). In agreement with experiment, we found that the vibrational progression increases with the polarity of the solvent, but we could neither reproduce the broadening, nor the large difference between the absorption spectra of HBDI and…

Application of FTIR Spectroscopy to Analyze RNA Structure

2020

Fourier transform infrared (FTIR) spectroscopy has been widely used for the analysis of both protein and nucleic acid secondary structure. This is one of the vibration spectroscopy methods that are extremely sensitive to any change in molecular structure. While numerous reports describe how to proceed to analyze protein and deoxyribonucleic acid (DNA) structures using FTIR, reports related to the analyses of ribonucleic acids (RNAs) are few. Nevertheless, RNAs are versatile molecules involved in a multitude of roles in the cell. In this chapter, we present applications of FTIR for the structural analysis of RNA, including the analysis of helical parameters and noncanonical base pairing, oft…

Use and limitations of ICP-OES in wine analysis

1989

At present, some 50 inorganic components in wine can be detected, of which 8 are mineral matter at concentrations down to 1 mg/l, about 25 are trace elements with concentrations of 0.001–0.1 mg/l, and about 20 are ultratrace elements at concentrations below 1 μg/1. It has been shown that ICP-OES, a typical multielement detection method, permits the fast and reliable simultaneous determination of whole range of these inorganic species in wine, and thus can help in solving practical problems in wine manufacture. For instance, the metal content of wine can be checked, and corrosion and contamination monitored. Ten trace elements (Al, Cd, Co, Cr, Cu, Fe, Mn, Pb, V, Zn) which may be toxic or to …

How subtle is the "terroir" effect? Chemistry-related signatures of two "climats de Bourgogne".

2014

The chemical composition of grape berries is influenced by various environmental conditions often considered to be representative of a "terroir". If grapes from a given terroir are assumed to reflect this origin in their chemical compositions, the corresponding wine should also reflect it. The aim of this work was therefore to reveal the "terroir" expression within the chemodiversity of grapes and related wines, using ultrahigh-resolution mass spectrometry. Grapes and corresponding wines, from two distinct - though very proximate - terroirs of Burgundy were analyzed over three vintages (2010, 2011 and 2012). Ultrahigh-resolution mass spectrometry and ultra-high performan…

Mesoscopic and Microscopic Investigation on Poly(vinyl alcohol) Hydrogels in the Presence of Sodium Decylsulfate

2007

The structure of poly(vinyl alcohol) (PVA) hydrogels formed as a result of freeze/thaw treatments of aqueous solutions of the polymer (11 wt % PVA) in the freshly prepared state is analyzed through the combined use of small (SANS) and ultrasmall (USANS) angle neutron scattering techniques. The structure of these hydrogels may be described in terms of polymer rich regions, with dimensions of the order of 1-2 microm, dispersed in a water rich phase, forming two bicontinuous phases. The PVA chains in the polymer rich phase form a network where the cross-linking points are mainly crystalline aggregates of PVA having average dimensions of approximately 45 A. The structural organization of freeze…

E-beam crosslinked, biocompatible functional hydrogels incorporating polyaniline nanoparticles

2012

Abstract PANI aqueous nanocolloids in their acid-doped, inherently conductive form were synthesised by means of suitable water soluble polymers used as stabilisers. In particular, poly(vinyl alcohol) (PVA) or chitosan (CT) was used to stabilise PANI nanoparticles, thus preventing PANI precipitation during synthesis and upon storage. Subsequently, e-beam irradiation of the PANI dispersions has been performed with a 12 MeV Linac accelerator. PVA-PANI nanocolloid has been transformed into a PVA-PANI hydrogel nanocomposite by radiation induced crosslinking of PVA. CT-PANI nanoparticles dispersion, in turn, was added to PVA to obtain wall-to-wall gels, as chitosan mainly undergoes chain scission…

2019

Negative image-based (NIB) screening is a rigid molecular docking methodology that can also be employed in docking rescoring. During the NIB screening, a negative image is generated based on the target protein’s ligand-binding cavity by inverting its shape and electrostatics. The resulting NIB model is a drug-like entity or pseudo-ligand that is compared directly against ligand 3D conformers, as is done with a template compound in the ligand-based screening. This cavity-based rigid docking has been demonstrated to work with genuine drug targets in both benchmark testing and drug candidate/lead discovery. Firstly, the study explores in-depth the applicability of different ligand 3D conformer…

Replication of Human Norovirus in Mice after Antibiotic-Mediated Intestinal Bacteria Depletion

2022

Human noroviruses (HuNoVs) are the main cause of acute gastroenteritis causing more than 50,000 deaths per year. Recent evidence shows that the gut microbiota plays a key role in enteric virus infectivity. In this context, we tested whether microbiota depletion or microbiota replacement with that of human individuals susceptible to HuNoVs infection could favor viral replication in mice. Four groups of mice (n = 5) were used, including a control group and three groups that were treated with antibiotics to eliminate the autochthonous intestinal microbiota. Two of the antibiotic-treated groups received fecal microbiota transplantation from a pool of feces from infants (age 1-3 months) or an au…