Search results for "liquid"
showing 10 items of 4351 documents
Intra-Tumour Genetic Heterogeneity and Prognosis in High-Risk Neuroblastoma
2021
Simple Summary Neuroblastoma (NB) is the most common extra-cranial solid paediatric cancer and is responsible for 15% of childhood cancer deaths. Patients with NB are characterized by presenting a very heterogeneous clinic (inter-tumoural heterogeneity) and also both spatial and temporal intra-tumour heterogeneity (ITH) reflected in their genetic aberrations, which may be the consequence of the coexistence of different microenvironments within the tumour. Applying pangenomic techniques to detect genomic aberrations in different biopsies (solid and liquid) of high risk NB (HR-NB) we have detected spatial ITH in a surprisingly high percentage (almost 40%) of the studied cohort. Moreover, a po…
Application of solid-phase microextraction for determining phenylurea herbicides and their homologous anilines from vegetables.
2004
Abstract Residues of metobromuron, monolinuron and linuron herbicides and their aniline homologous were analyzed in carrots, onions and potatoes by solid-phase microextraction (SPME) performed with a polyacrylate fiber. A juice was obtained from food samples that were further diluted, and an aliquot was extracted after sodium chloride (14%) addition and pH control. At pH 4 only the phenylureas were extracted. A new extraction at pH 11 allowed the extraction of phenylureas plus homologous aniline metabolites. Determination was carried out by gas chromatography with nitrogen–phosporus detection (NPD) the identity of the determined compounds was studied by gas chromatography–mass spectrometry.…
ortho -Fluorination of azophenols increases the mesophase stability of photoresponsive hydrogen-bonded liquid crystals
2018
Photoresponsive liquid crystals (LCs) whose alignment can be controlled with UV-Visible light are appealing for a range of photonic applications. From the perspective of exploring the interplay between the light response and the self-assembly of the molecular components, supramolecular liquid crystals are of particular interest. They allow elaborating the structure-property relationships that govern the optical performance of LC materials by subtle variation of the chemical structures of the building blocks. Herein we present a supramolecular system comprising azophenols and stilbazoles as hydrogen-bond donors and acceptors, respectively, and show that ortho-fluorination of the azophenol dr…
Determination of organophosphate flame retardants in soil and fish using ultrasound-assisted extraction, solid-phase clean-up, and liquid chromatogra…
2017
A solid–liquid extraction method in combination with high‐performance liquid chromatography and tandem mass spectrometry was developed and optimized for extraction and analysis of organophosphorus flame retardants in soil and fish. Methanol was chosen as the optimum extraction solvent, not only in terms of extraction efficiency, but also for its broader analyte coverage. The subsequent clean‐up by solid‐phase extraction is required to eliminate matrix coextractives and reduce matrix effects. Recoveries of the optimized method were 50–121% for soil and 47–123% for biota, both with high precision (RSDs <12% in soil and <23% in biota). The method limits of detection ranged from 0.06 to 0.20 ng…
Network-Based Computational Techniques to Determine the Risk Drivers of Bank Failures During a Systemic Banking Crisis
2018
This paper employs a computational model of solvency and liquidity contagion assessing the vulnerability of banks to systemic risk. We find that the main risk drivers relate to the financial connections a bank has and the market concentration, apart from the size of the bank triggering the contagion, while balance sheets play only a minor role. We also find that market concentration might facilitate banks to withstand liquidity shocks better while exposing them to larger solvency chocks. Our results are validated through an out-of-sample forecasting that shows that both type I and type II prediction errors are reduced if we include network characteristics in our prediction model.
Evaluation of advanced silica packings for the separation of biopolymers by high-performance liquid chromatography
1989
Abstract The linear solvent strength model of Snyder was applied to describe fast protein separations on 2.1-μm non-porous, silica-based strong anion exchangers. It was demonstrated on short columns packed with these anion exchangers that (i) a substantially higher resolution of proteins and nucleotides was obtained at gradient times of less than 5 min than on porous anion exchangers; (ii) the low external surface area of the non-porous anion exchanger is not a critical parameter in analytical separations and (iii) μg-amounts of enzymes of high purity and full biological activity were isolated.
ChemInform Abstract: Di- and Tricationic Organic Salts: An Overview of Their Properties and Applications
2014
During recent years growing interest has been devoted to the synthesis and applications of polycationic organic salts. Among them, di- and tricationic organic salts can be considered the natural evolution of monocationic ones. These last have given rise to the large class of ionic liquids. In the cases of di- and tricationic organic salts, the potential to change their structural features simply by varying the properties either of the charged heads or of the spacers separating them provides the opportunity to obtain materials suitable for different applications. This review article highlights recent progress in the study of the properties of di- and tricationic organic salts, as well as in …
Computerized Interpretation of H P L C Chromatogramms by Means of Absorbance Ratio Method and Derivative Spectroscopy
1985
As in other chromatographic processes it is the aim of high pressure liquid chromatography (HPLC) to identify the components of a mixture, whereby there may be some information on the class of substances in question. The analytical procedure can shortly be desribed as follows. The mixture is injected in a mobile phase (solvent) and passes a column where the separation takes place. The separated components leave the column at different retention times. A following detection device generates a signal as a function of concentration (chromatographic peak). Usually the components are identified by relating retention times of external standards to the times of occurence of chromatographic peaks. …
Reversed-phase liquid chromatography with mixed micellar mobile phases of Brij-35 and sodium dodecyl sulphate: a method for the analysis of basic com…
2015
Micellar liquid chromatography (MLC) is a reversed-phase liquid chromatographic (RPLC) mode, which uses a surfactant as a modifier, with significant changes in retention and selectivity with regard to the classical RPLC mode that employs mixtures of water and organic solvent. The anionic sodium dodecyl sulphate (SDS) is the most usual surfactant in MLC, but it also requires the addition of an organic solvent to decrease the retention times and increase the efficiency. In particular, positively charged basic compounds are strongly retained by the stationary phase modified by adsorption of SDS monomers and require the addition of a strong solvent, such as propanol or pentanol. The non-ionic s…
Phosphatidylcholine-Gramicidin a Interaction Study in Non-Aqueous Solvent with a new HPLC-SEC Column
1985
Abstract A new HPLC-SEC column, Ultrastyragel 500 A, has been assayed in order to check the separation between gramicidin A and phosphatidylcholine in tetrahydrofuran. The good resolution of both compounds has allowed the quantitation of lipid-polypeptide interaction in terms of the binding ratio parameter, BR. A BR value of 3.6 moles of phosphatidylcholine per mole of gramicidin A has been obtained for a 0.1 % (w/v) phosphatidylcholine solution as eluent. The suitability of this support for studies on lipid-polypeptide interactions in non-aqueous solvents is demonstrated.