Search results for "ionic"
showing 10 items of 2016 documents
Controllable Nonspecific Protein Adsorption by Charged Hyperbranched Polyglycerol Thin Films
2015
Antifouling thin films derived from charged hyperbranched polyglycerol (hbPG) layers were fabricated and evaluated. The anionic hbPG (a-hbPG) monolayers and cationic hbPG/anionic hbPG (c/a-hbPG) bilayers were adsorbed on the underlying self-assembled monolayers (SAMs) of cysteamine and 3-mercaptopropionic acid (3-MPA) by electrostatic interaction, respectively, and their procession was monitored by surface plasmon resonance spectroscopy (SPR). The adsorption of bovine serum albumin (BSA) and fibrinogen on the premade a-hbPG and c/a-hbPG thin films was measured and the capability of these thin films to resist nonspecific protein adsorption was evaluated by SPR as well. It is observed that th…
The second component of human complement: Use of glycosidases and glucosylation to distinguish the two forms
1988
Abstract The two forms of human plasma C2 that were described in the preceding report (1) were investigated for their functional and biochemical differences. Incubation with the neuraminidase (NAN'dase) of Clostridium perfringens at 37°C resulted in a four- to fivefold increase in the hemolytic activity of both forms. The increase in activity was different than the increase caused by treatment with iodine. The mechanism of increased activity of NAN'dase-treated C2 was the generation of increased molecules of activated C3 (C3b), resulting in more molecules of C5 binding to (C4b, 2a, 3b)n. Removal of N-acetyl-neuraminate from C2 did not alter its binding to a cationic exchanger. Nonenzymatic …
Silicate adsorption by goethite at elevated temperatures
2009
Abstract Batch adsorption experiments with relatively low silica concentrations between 10 µM and 100 µM were conducted at three different ionic strength (0.01 − 0.1 M), and four different temperatures between 10 °C and 75 °C, yielding in a total of 550 experimental data points. The residual concentration of monosilicic acid is controlled by an adsorption equilibrium which is dependent on pH. The % Si adsorbed vs. − log[H + ] curves reveal an upward bend with a maximum at about a pH of 9. With acidification below pH 9 the residual Si concentration in the suspensions steadily increases, as well as in the increasingly alkaline pH range. The slope of the latter is becoming steeper with increa…
A DFT investigation of CO oxidation over neutral and cationic gold clusters
2009
Abstract The interaction of CO and O 2 with neutral and positively charged Au 9 and Au 13 clusters was studied using Density Functional Theory. The aim was the understanding of the elementary steps of the low temperature activity of supported gold nanoparticles towards carbon monoxide combustion, that is, the oxidation of CO to CO 2 in presence of dioxygen molecules. The adsorption of a single CO molecule gives rise to a substantial electronic rearrangement on both neutral and cationic gold clusters. On the contrary, the adsorption of dioxygen produces an electron transfer from neutral gold clusters to the O 2 , while the interaction with cationic Au nanoparticles is simply electrostatic. C…
La fortuna del capitello ionico nella Gortina imperiale: i modelli microasiatici e le rielaborazioni in marmo grigio locale
2020
Le indagini archeologiche nella città di Gortina hanno riportato in luce alcuni capitelli ionici di modello microasiatico in marmo importato, databili alla seconda metà del II sec. d.C., ma anche un gran numero di capitelli ionici in marmo grigio locale, con ogni evidenza prodotti in loco tra la fine del II e gli inizi del III sec. d.C. Si tratta di membrature riutilizzate in edifici più tardi e spesso reimpiegate come materiale da costruzione o rifunzionalizzate in vari modi. La loro relativa abbondanza, per alcuni versi insolita, testimonia non solo la peculiare fortuna del tipo nella capitale cretese, ma anche la grande attività degli atelier di scalpellini locali, almeno a partire dalla…
DEEP EUTECTIC SOLVENTS E LIQUIDI IONICI: SOLVENTI PER LO SVILUPPO DI PROCESSI ECO-COMPATIBILI
2020
L’obiettivo di questi tre anni di Dottorato è stato lo studio e l’utilizzo nuovi solventi di reazione in grado di sostituire i solventi organici classici. In particolare sono stati studiati i Deep Eutectic Solvent (DES) e le miscele di Liquidi Ionici (IL). I DES sono stati utilizzati come solventi per lo studio di reazioni organiche, usate per la formazione di nuovi legami C-C. Nello specifico sono state studiate la reazione di Diels-Alder, e diverse reazioni di coupling C-C catalizzate da Pd. In seguito, i DES sono stati utilizzati per la formazione di nuovi gel supramolecolari, chiamati eutectogel. Questi gel sono stati formati usando come gelator amminoacidi naturali, consentendo quindi …
Electrochemical Amination of Less-Activated Alkylated Arenes Using Boron-Doped Diamond Anodes
2016
The anodic C–H amination of aromatic compounds is a powerful and versatile method for the synthesis of aniline derivatives. By using boron-doped diamond (BDD) anodes, a method initially described by Yoshida et al. for electron-rich arenes was expanded to less-activated aromatic systems e.g., simple alkylated benzene derivatives. Anodes based on sp3 carbon seem to be the key for the electrochemical amination reaction. The corresponding primary anilines are obtained in good yields. Despite the cationic intermediates of the electrolytic reaction tert-butyl moieties are tolerated.
Boosting the methanolysis of polycarbonate by the synergy between ultrasound irradiation and task specific ionic liquids
2021
In an attempt to perform polycarbonate chemical recycling in a more sustainable way, we took into consideration the combined use of ultrasound irradiation and task specific ionic liquids. Towards this aim, the methanolysis of polycarbonate, into dimethylcarbonate and bisphenol A, was carried out in the presence of cholinium-based ionic liquids featuring anions derived from amino acids and other eco-friendly species. The target process was optimized in terms of both energy and material amounts as well as in terms of the nature of the catalysts used. The proposed protocol allowed high conversion and yields of bisphenol A to be obtained, under milder conditions compared to the ones so far repo…
Versatile Electrochemical C-H Amination via Zincke Intermediates.
2015
Simply by applying electricity, the amination reaction of a broad variety of arenes, heteroarenes, and benzylic substrates is achieved. Pyridine serves as the nitrogen source and the intermediate cationic species are well-protected from over-oxidation.
Ionic liquids as precatalysts in the highly stereoselective conjugate addition of α,β-unsaturated aldehydes to chalcones.
2014
Imidazolium-based ionic liquids (ILs) serve both as recyclable reaction media and as precatalysts for the N-heterocyclic carbene-catalyzed conjugate addition of α,β-unsaturated aldehydes to chalcones. The reaction produces a broad scope of 1,6-ketoesters incorporating an anti-diphenyl moiety in high yields and with high stereoselectivity. In recycling experiments, the IL can be reused up to five times with retained reactivity and selectivity. Moreover, the 1,6-ketoesters form self-assembled organogels in aliphatic hydrocarbons. The reaction protocol is robust, easily operated, scalable and highly functionalized compounds can be obtained from inexpensive and readily accessible starting mater…