Search results for "liquid [scintillation counter]"

Cheese flavour : instrumental techniques

2004

This chapter discusses instrumental techniques to analyze cheese flavor. It focuses on recent advances made to study and identify the taste-active components present in the water-soluble fraction of cheese. A general procedure for the preparation of fractions involves an extraction of grated cheese by water followed by a fractionation scheme, generally adapted from the fractionation protocol used to isolate cheese nitrogen fractions in the study of proteolysis in cheese during ripening. However, as sub-fractions have to be evaluated sensorially to assess their relative sensory impact and try to link it to their chemical composition, a suitable eluent has to be used in the chromatographic st…

Ionic liquid crystals based on viologen dimers: tuning the mesomorphism by varying the conformational freedom of the ionic layer

2016

ABSTRACTWe investigated the liquid crystal behaviour of newly synthesised bistriflimide salts of symmetric viologen dimers. A smectic A phase was observed for intermediate spacer lengths and for relatively long lateral alkyl chains. The systems were characterised by thermal analysis, polarised optical microscopy, X-ray scattering and solid-state NMR. An intermediate ordered smectic phase was also exhibited by the compounds (except for systems with very short lateral chains) consisting of molten layers of alkyl chains and partially ordered ionic layers. These results, relating to the mesomorphic behaviour of viologen salts, are qualitatively compared to those of the more common imidazolium s…

Surface charges at the CaF2/water interface allow very fast intermolecular vibrational-energy transfer

2020

Abstract We investigate the dynamics of water in contact with solid calcium fluoride, where at low pH, localized charges can develop upon fluorite dissolution. We use 2D surface‐specific vibrational spectroscopy to quantify the heterogeneity of the interfacial water (D2O) molecules and provide information about the sub‐picosecond vibrational‐energy‐relaxation dynamics at the buried solid/liquid interface. We find that strongly H‐bonded OD groups, with a vibrational frequency below 2500 cm−1, display very rapid spectral diffusion and vibrational relaxation; for weakly H‐bonded OD groups, above 2500 cm−1, the dynamics slows down substantially. Atomistic simulations based on electronic‐structu…

Influences of Ortho‐Fluoroazobenzenes on Liquid Crystalline Phase Stability and 2D (Planar) Actuation Properties of Liquid Crystalline Elastomers

2019

Tristriazolotriazines with Azobenzene Arms ‐ Acidochromic Dyes and Discotic Liquid Crystals

2019

Synthesis, Thermal, and Optical Properties of Tris(5‐aryl‐1,3,4‐oxadiazol‐2‐yl)‐1,3,5‐triazines, New Star‐Shaped Fluorescent Discotic Liquid Crystals

2019

Abstract The synthesis of tris(aryloxadiazolyl)triazines (TOTs), C 3‐symmetrical star‐shaped mesogenes with a 1,3,5‐triazine center, 5‐phenyl‐1,3,4‐oxadiazole arms, and various peripheral alkoxy side chains is reported. Threefold Huisgen reaction on a central triazine tricarboxylic acid and suitable aryltetrazoles yields the title compounds. Selected analogues with a benzene center are included in this study and allow for an evaluation of the impact of the central unit on the physical properties. Thermal (differential scanning calorimetry, DSC; polarization optical microscopy, POM), optical (UV/Vis, fluorescence), electric (time of flight, TOF), and structural (single crystal; wide‐angle X‐…

Desarrollo de nuevas estrategias para el diseño de técnicas de cromatografía líquida miniaturizada en línea: nanopartículas, contaminación secundaria

2019

In recent years one of the most important trends in Analytical Chemistry has been the development of new analytical methodologies based on the miniaturization, simplification and automatization of the analytical process, in order to reduce the environmental impact of the analysis without compromising the sensitivity and selectivity. In this respect miniaturized liquid chromatography (LC) systems, such as capillary liquid chromatography (CapLC) and nanoliquid chromatography (NanoLC) are important achievements. These techniques are environmental friendly because the amount of material involved is limited and organic solvents, electricity and the wastes generated are lower than in conventional…

Polyoxypregnanes as safe, potent, and specific ABCB1-inhibitory pro-drugs to overcome multidrug resistance in cancer chemotherapy in vitro and in vivo

2021

Multidrug resistance (MDR) mediated by ATP binding cassette subfamily B member 1 (ABCB1) is significantly hindering effective cancer chemotherapy. However, currently, no ABCB1-inhibitory drugs have been approved to treat MDR cancer clinically, mainly due to the inhibitor specificity, toxicity, and drug interactions. Here, we reported that three polyoxypregnanes (POPs) as the most abundant constituents of Marsdenia tenacissima (M. tenacissima) were novel ABCB1-modulatory pro-drugs, which underwent intestinal microbiota-mediated biotransformation in vivo to generate active metabolites. The metabolites at non-toxic concentrations restored chemosensitivity in ABCB1-overexpressing cancer cells v…

Metabolic signatures across the full spectrum of non-alcoholic fatty liver disease.

2022

Funder: European Commission

Analysis of emerging and related pollutants in aquatic biota

2020

Water bodies cover approximately 70 % of the earth s surface, making them ecosystems with a high environmental value and the habitat for numerous species of flora and fauna. Emerging pollutants (EPs) are ubiquitous anthropogenic compounds of environmental concern that can be found at different concentration levels in matrices such as sediment, water and aquatic biota. In addition, EPs can be bioaccumulated and biomagnified, inducing adverse effects on biota, and posing a risk to humans when contaminated biota is consumed. Unlike abiotic matrices, the occurrence of EPs in aquatic biota has not been widely studied. This is probably because their complexity, due to the presence of lipids, prot…