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α-Amylase from Aspergillus oryzae was covalently immobilized onto polystyrene pellets with pentaethylenehexamine (PS-PEHA-Ald) and pentaethylene glycol (PS-PG-Ald) carrying a terminal aldehyde group. Optimum immobilization occured at pH 8.0 and 25 °C, and at pH 7.0 and 35 °C for PS-PEHA-Ald and PS-PG-Ald, respectively. PS-PEHA-Ald immobilized enzyme… (More)
We have investigated the UV-visible light transmission of three types of micrometre-sized sporopollenin exine shells, two derived from Lycopodium clavatum (club moss) spores and one from Ambrosia trifida (giant ragweed) pollen. We have used spectrophotometer measurements of partial monolayers of exines and microscope absorbance imaging to derive the light… (More)
A novel polyamine microsphere, prepared from the water-in-oil emulsion of polyethylenimine, was characterized. The investigation of scanning electron microscopy showed that the polyamine microsphere is a regular ball with a smooth surface. The diameter distribution of the microsphere is 0.37-4.29 μm. The isoelectric point of the microsphere is 10.6. The… (More)
A facile method for synthesis of CdS nanoparticles has been described. Monodisperse face-centered cubic CdS NPs could be synthesized in switchable surfactant reverse micelles. The micelles could be broken easily and CdS NPs without a coating of surfactants could be obtained by bubbling N(2) at 65 °C.
pH-responsive oil-in-water Pickering emulsions were prepared simply by using negatively charged silica nanoparticles in combination with a trace amount of a zwitterionic carboxyl betaine surfactant as stabilizer. Emulsions are stable to coalescence at pH ≤ 5 but phase separate completely at pH > 8.5. In acidic solution, the carboxyl betaine molecules become… (More)
Back and forth: The CO2 /N2 trigger of a switchable surfactant (neutral amidine/cationic amidinium) was transferred to mineral nanoparticles through in situ hydrophobization in water. Switchable oil-in-water Pickering emulsions that entail a CO2 /N2 trigger were obtained by using negatively charged silica nanoparticles and a trace amount of the switchable… (More)
In the recent past there has been a growing interest in switchable surfactants and stimuli-responsive surface-active particles, since both have surface activity which is either switchable or controllable and they can be recovered and re-used afterwards. Among various triggers the CO2/N2 trigger is particularly environmentally benign. In this paper a facile… (More)
CO2/N2 and light dual stimuli-responsive worm-like micelles (WLMs) were obtained by addition of a relatively small amount of a switchable surfactant, 4-butyl-4'-(4-N,N-dimethylhexyloxy-amine) azobenzene bicarbonate (AZO-B6-CO2), sensitive to the same triggers to a binary aqueous solution of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal).
In the recent past, switchable surfactants and switchable/stimulus-responsive surface-active particles have been of great interest. Both can be transformed between surface-active and surface-inactive states via several triggers, making them recoverable and reusable afterward. However, the synthesis of these materials is complicated. In this paper we report… (More)
We put forward a simple protocol to prepare thermoresponsive Pickering emulsions. Using hydrophilic silica nanoparticles in combination with a low concentration of alkyl polyoxyethylene monododecyl ether (C12En) nonionic surfactant as emulsifier, oil-in-water (o/w) emulsions can be obtained, which are stable at room temperature but demulsified at elevated… (More)