Search results for " Ion Exchange"
showing 10 items of 65 documents
Current concepts in the prevention of pathogen transmission via blood/plasma-derived products for bleeding disorders
2015
The pathogen safety of blood/plasma-derived products has historically been a subject of significant concern to the medical community, Measures such as donor selection and blood screening have contributed to increase the safety of these products, but pathogen transmission does still occur. Reasons for this include lack of sensitivity/specificity of current screening methods, lack of reliable screening tests for some pathogens (e.g. prions) and the fact that many potentially harmful infectious agents are not routinely screened for. Methods for the purification/inactivation of blood/plasma-derived products have been developed in order to further reduce the residual risk, but low concentrations…
Human liver cytosolic epoxide hydrolases.
1988
Human liver epoxide hydrolases were characterized by several criteria and a cytosolic cis-stilbene oxide hydrolase (cEHcso) was purified to apparent homogeneity. Styrene oxide and five phenylmethyloxiranes were tested as substrates for human liver epoxide hydrolases. With microsomes activity was highest with trans-2-methylstyrene oxide, followed by styrene 7, 8-oxide, cis-2-With methylstyrene oxide, cis-1,2-dimethylstyrene oxide, trans-1, 2-dimethylstyrene oxide and 2, 2-dimethylstyrene oxide. With cytosol the same order was obtained for the first three substrates, whereas activity with 2, 2-dimethylstyrene oxide was higher than with cis-1,2-dimethylstyrene oxide and no hydrolysis occurred …
Influence of nifedipine on the metabolism of gingival fibroblasts.
1994
Calcium antagonists are the gold standard in the therapy of coronary heart disease and hypertension. The prototype of these drugs is nifedipine which, as well as its therapeutic effects on the cells of the cardiovascular system, also has unpleasant side effects on other organ systems. One side effect can be a missive hyperplasia of the gingiva, the reason for which are unclear. In vitro experiments were designed to elucidate the influence of nifedipine on the growth of human gingival fibroblasts in short and long term (72 hours, 6 weeks) cell culture. The following cellular parameters were determined quantitatively: cell proliferation (cell count, [3H]thymidine incorporation), protein synth…
Progesterone increases basal 3',5'-cyclic adenosine monophosphate formation and down-regulates the agonist-induced inositol phosphates generation in …
1992
Whether the placenta is a target tissue for estrogens and progesterone, and their putative mechanism of action, is still a controversial question in the literature. The effect of progesterone and estradiol on 3′,5′-cyclic adenosine monophosphate (cAMP) and inositol phosphates generation in human term placenta was investigated. Placental explants were incubated in vitro for up to 48 h in the absence and in the presence of estradiol, progesterone or both steroids (0.1 μmol/l final concentration in all cases), and were stimulated with terbutaline, a β-adrenergic agonist, (0.1 mmol/l) or angiotensin II(1 μmol/l), The cAMP content was measured by a competitive protein binding assay, and the gene…
Surface charge fine tuning of reversed-phase/weak anion-exchange type mixed-mode stationary phases for milder elution conditions.
2015
A series of new mixed-mode reversed-phase/weak anion-exchange (RP/WAX) phases have been synthesized by immobilization of N-undecenyl-3-α-aminotropane onto thiol-modified silica gel by thiol-ene click chemistry and subsequent introduction of acidic thiol-endcapping functionalities of different type and surface densities. Click chemistry allowed to adjust a controlled surface concentration of the RP/WAX ligand in such a way that a sufficient quantity of residual thiols remained unmodified which have been capped by thiol click with either 3-butenoic acid or allylsulfonic acid as co-ligands. In another embodiment, performic acid oxidation of N-undecenyl-3-α-aminotropane-derivatized thiol-modifi…
Determination of fatty alcohol ethoxylates and alkylether sulfates by anionic exchange separation, derivatization with a cyclic anhydride and liquid …
2011
A method for the separation, characterization and determination of fatty alcohol ethoxylates (FAE) and alkylether sulfates (AES) in industrial and environmental samples is described. Separation of the two surfactant classes was achieved in a 50:50 methanol-water medium by retaining AES on a strong anionic exchanger (SAX) whereas most FAE were eluted. After washing the SAX cartridges to remove cations, the residual hydrophobic FAE were eluted by increasing methanol to 80%. Finally, AES were eluted using 80:20 and 95:5 methanol-concentrated aqueous HCl mixtures. Methanol and water were removed from the FAE and AES fractions, and the residues were dissolved in 1,4-dioxane. In this medium, este…
N-Propyl-N′-2-pyridylurea-modified silica as mixed-mode stationary phase with moderate weak anion exchange capacity and pH-dependent surface charge r…
2018
Herein, we present a novel silica-based stationary phase modified with N-propyl-N'-2-pyridylurea selector. Due to the weakly basic properties of the pyridine selector and the presence of residual silanols after selector immobilization, a zwitterionic surface with a pI observed at approximately pH 5.5 was measured by electrophoretic light scattering in pH-dependent ζ-potential determinations. The capability of the new N-propyl-N'-2-pyridylurea-modified silica to serve as mixed-mode stationary phase was investigated. For this purpose, it was characterized under RP and HILIC conditions using test mixtures. Subsequent classification of this stationary phase in comparison to in-house and commerc…
Stable-bond polymeric reversed-phase/weak anion-exchange mixed-mode stationary phases obtained by simultaneous functionalization and crosslinking of …
2019
Abstract A polymeric reversed-phase/weak anion exchange (Poly-RP/WAX) mixed-mode stationary phase has been prepared by coating of a poly(3-mercaptopropyl)methylsiloxane film on vinyl-modified silica (100 A, 5 μm) and simultaneous in situ functionalization with N-(10-undecenoyl)-3-aminoquinuclidine as well as crosslinking to the vinyl silica surface by solventless thiol-ene double click reaction. Such bonding chemistry showed greatly enhanced stability compared to brush-type analogs with bifunctional siloxane bonding to silica. Solid-state 29Si-CP/MAS NMR confirmed the immobilization of the siloxane layer. pH-Dependent ζ-potential determinations revealed a high anion-exchange capacity over t…
Determination of non-ionic and anionic surfactants in industrial products by separation on a weak ion-exchanger, derivatization and liquid chromatogr…
2013
Abstract A method for the determination of priority surfactants, including fatty alcohol ethoxylates (FAE), alkylether sulfates (AES) and linear alkylbenzene sulfonates (LAS) is described. The samples were diluted with 50% methanol at pH 4 prior to solid-phase extraction on a weak anionic exchanger (WAX). The AES and LAS surfactant classes were retained, whereas the non-ionic components, including most FAE oligomers were eluted. After washing the WAX cartridge to remove cations, the remaining hydrophobic FAE oligomers were eluted using hot 80% methanol at pH 4 (at ca. 50 °C). These two eluates were combined to constitute the non-ionic fraction. Then, AES and LAS were eluted using 80% MeOH w…
Towards sustainable production of minerals and chemicals through seawater brine treatment using Eutectic freeze crystallization and Electrodialysis w…
2022
European policy encourages the adoption of sustainable systems that promote the efficient use and recovery of minerals and chemicals. In this respect, desalination brines do contain a dramatic amount of valuable minerals and can be valorized through appropriate treatments rather than releasing them into the environment. This paper proposes an innovative brine recovery system for obtaining high purity chemicals through the integration of Eutectic Freeze Crystallization (EFC) and Electrodialysis with Bipolar Membrane (EDBM) technologies. Two separate laboratory-scale experimental campaigns were carried out to validate the potential integration of the two processes. Mirabilite (Na2SO4∙10H2O) h…