Search results for "modification"

EVALUATION OF THE ELUTION STRENGTH OF THE SURFACTANT AND ORGANIC SOLVENT IN HYBRID MICELLAR MOBILE PHASES

2001

The global ability of a mixed mobile phase (with two or more modifiers) to elute a solute is often measured without distinguishing between the elution strength of each modifier. An algorithm is proposed to evaluate the elution strength of the modifiers in hybrid micellar mobile phases containing a surfactant and an organic solvent. The algorithm is based on a mechanistic retention model that takes into account the competing equilibria of solutes among aqueous-organic phase, micelle, and stationary phase. The change in the elution strength of surfactant and organic solvent with respect to the concentration of both modifiers is also examined. The results are discussed according to the values …

Column technology in liquid chromatography

2017

This chapter deals with the most important part of the liquid chromatography (LC) system: the column enabling the efficient and fast resolution of complex mixtures. It is divided into seven sections under the overall aspects of manufacture, operation, and evaluation of analytical columns for the user. The first three sections highlight the column design and hardware, followed by a thorough treatment of the properties of microparticulate silica adsorbents as packing material, stationary phases performed by surface functionalization, and the column filling process. Then, the implementation of the column into the LC system is discussed, leading into chromatographic column testing as a C18-bond…

Hydrolytically stable chemically bonded silica supports with metal complexating ligands: Synthesis, characterization and use in high-performance liga…

1982

A silica of 14 nm pore size was reacted according to two procedures with the following silanes: γ-aminopropyltriethoxysilane (1), N-aminoethyl-N′-aminopropyltrimethoxysilane (2), N-aminoethyl-N′-aminoethyl-N″-aminopropyltrimethoxysilane (3), N-(3-triethoxysilanepropyl)-N, N-diacetic dimethylester (4), N-(3-trisodiumsilanolatepropyl)-N, N-diacetic acid disodium salt (5) and N-(3-trisodiumsilanolatepropyl)-ethylenediamine-N, N′, N′-triacetic acid trisodium salt (6). The reaction of silanes 1–4 with the silica was carried out under anhydrous conditions (procedure A). Silanes 1–6 were subjected to surface modification under essentially hydrous conditions applying a two-step procedure (procedure…

A facile way to build up branched high functional polyaminoacids with tunable physicochemical and biological properties

2016

Abstract Here, for the first time, branched polyaminoacids bearing α-amino acids as side functions, namely PAA-co-AA and PGA-co-AA, are prepared by heterophase ring opening of polysuccinimide (PSI) with l -arginine or glycine in aqueous environment and at controlled pH. The modulation of the pH of the reaction leads to high-molecular-weight copolymers with tunable functionalization and, as consequence, with tailor-made physicochemical properties. Furthermore, a branched polyaminoacid carrying a preformed bioactive peptide ( l -trileucine) and l -arginine as side pendants, named PATA-co-AA, was synthesized via a similar pathway thus leading to complex biomimetic materials potentially exploit…

Chemical Modification of Calix[4]arenes and Resorcarenes

2001

Weighing, Commodification, and Money

2013

The Marketisation of Higher Education: Antecedents, Processes, and Outcomes

2021

This chapter explores the ideological antecedents, processes, and outcomes of the marketisation of higher education, with an emphasis on business schools in particular. The chapter begins with a discussion of the theory of Scandinavian New Institutionalism in the context of higher education, explaining how ideologies spread across nations and fields through adoption and adaptation. It then elaborates the ideologies of neoliberalism and managerialism, and their relation to New Public Management. The chapter continues by elucidating the processes which are related to marketisation—namely commodification, corporatisation, and de-professionalisation. It then enumerates the various outcomes of t…

Between commodification and altruism: gender imbalance and attitudes towards organ donation. A representative survey of the German community

2008

The German transplant law (TGP) of 1997 only recognises organ donation if the donor agrees (‘extended consent’) and if done for altruistic reasons. Several alternatives will be discussed here, including incentives and passive agreement. Based upon a representative survey, the authors examined the attitudes of Germans towards several European models of organ donation and their attitude towards organ donation in general whilst living and after death. The acceptance of possible compensation systems was also explored. In Germany the majority do not favour compensation systems, but rather passive agreement. There is evidence of gender difference with respect to this attitude. Men tend to favour …

Recent Advances in Photocatalytic Functionalization of Quinoxalin‐2‐ones

2020

Quinoxalin‐2(1H)‐one is an important class of nitrogen heterocycle in medicinal and pharmaceutical industry, which became a synthetic target in organic chemistry in recent years. This review covers the recent advances in the functionalization of this particular nitrogen heterocycle through photocatalysis.

Influence of Pendant Arms Bearing Ligating Groups on the Structure of Bismuth Porphyrins: Implications for Labeling Immunoglobulins Used in Medical A…

2004

International audience; The synthesis of two picket bismuth(III) porphyrins is reported, and their crystal structures are compared. The influence of the nature of the pickets, as well as their number, is discussed in terms of stability, kinetics of metalation, structure, and distortion of the porphyrin. Unexpectedly, the resultsindicate that the coordination sphere of bismuth is not affected by different types of distortion nor is the stability of the complex. For both types of complexes, the X-ray crystallography revealed that a single arm is actually in direct interaction with the bismuth cation, thereby allowing furtherfunctionalization on the porphyrin core as the linkage with immunoglo…