Search results for " surface"
showing 10 items of 2838 documents
Die intramolekulare, radikalische kopf-schwanzbzw. Kopf-Kopf-addition von Phenylen-, Naphthylen- und Biphenylenbis(methacrylat)en
1977
1,2-, 1,3- und 1,4-Phenylenbis(methacrylat) (1a), (1b) und (1c), 2,3- und 1,6-Naphthylenbis(methacrylat) (2a) und (2b) sowie 2,2′-Biphenylenbis(methacrylat) (3) wurden nach einer bekannten Vorschrift dargestellt. Setzt man stark verdunnte Losungen dieser phenolischen Bisester in siedendem Benzol einem grosen Uberschus an 2-Cyano-2-propylradikalen R. (aus AIBN) aus, so entstehen neben wenigen olig-viskosen Produkten hauptsachlich kristallisierbare Verbindungen. Sie entstanden aus der intramolekularen Addition der zwei Methacrylatgruppen und Anlagerung von zwei Radikalen R · je Molekel. 1c gab nur eine derartige Verbindung, die nach den Elementaranlysen, der rel. mol. Masse, spektroskopischen…
Enhanced in vivo targeting of murine nonparenchymal liver cells with monophosphoryl lipid A functionalized microcapsules.
2014
A broad spectrum of infectious liver diseases emphasizes the need of microparticles for targeted delivery of immunomodulatory substances to the liver. Microcapsules (MCs) are particularly attractive for innovative drug and vaccine formulations, enabling the combination of antigen, drugs, and adjuvants. The present study aimed to develop microcapsules characterized by an enhanced liver deposition and accelerated uptake by nonparenchymal liver cells (NPCs). Initially, two formulations of biodegradable microcapsules were synthesized from either hydroxyethyl starch (HES) or mannose. Notably, HES-MCs accumulated primarily in the liver, while mannose particles displayed a lung preference. Functio…
When Functionalization of PLA Surfaces Meets Thiol−Yne Photochemistry: Case Study with Antibacterial PolyaspartamideDerivatives
2014
International audience; In this work we wish to report on the covalent functionalization of polylactide (PLA) surfaces by photoradical thiol–yne to yield antibacterial surfaces. At first, hydrophilic and hydrophobic thiol fluorescent probes are synthesized and used to study and optimize the conditions of ligation on alkyne-PLA surfaces. In a second part, a new antibacterial polyaspartamide copolymer is covalently grafted. The covalent surface modification and the density of surface functionalization are evaluated by SEC and XPS analyses. No degradation of PLA chains is observed, whereas covalent grafting is confirmed by the presence of S2p and N1s signals. Antiadherence and antibiofilm acti…
Analyse von Copolymeren aus Vinylestern und Acrylestern
1978
Die Copolymeren aus Vinyl- und Acrylestern werden in abgeschmolzenen Ampullen durch 2 M NaOH verseift. Die aus den Vinylester-Grundbausteinen gebildeten Sauren werden durch potentiometrische Titration bestimmt; liegen verschiedene Vinylester nebeneinander vor, so wird das Mengenverhaltnis der Sauren gaschromatographisch ermittelt. Die bei der Verseifung aus den Acrylester-Grundbausteinen entstehenden Alkohole werden gaschromatographisch identifiziert und gegen tert-Butanol als internen Standard quantitativ bestimmt. Ein besonderer Vorteil der Methode besteht darin, das auch wasrige Dispersionen ohne vorherige Abtrennung des Copolymeren eingesetzt werden konnen. The copolymers from vinyl est…
Physicochemical investigation of cobalt?iron cyanide nanoparticles synthesized by a novel solid?solid reaction in confined space
2004
Cobalt–iron cyanide (Cox[Fe(CN)6]) nanoparticles have been synthesized by a novel solid–solid reaction in the confined space of dry sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reversed micelles dispersed in n-heptane. The reaction has been carried out by mixing two dry AOT/n-heptane solutions containing CoCl2 and K4Fe(CN)6 or K3Fe(CN)6 nanoparticles in the micellar core, respectively. By UV-Vis spectroscopy it was ascertained that, after the mixing process, the formation of stable nanoparticles is fast and complete. Microcalorimetric measurements of the thermal effect due to the Cox[Fe(CN)6] nanoparticle formation allowed the determination of the stoichiometric ratio (x) and of the molar e…
FT-IR investigation of the acetamide state in AOT reversed micelles
2003
The state of acetamide nanoparticles encapsulated in the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reversed micelles and dispersed in CCl4 has been investigated by Fourier transform infrared spectroscopy. The analysis of the vibrational spectra reveals even at the higher acetamide to AOT molar ratio some changes of the typical H-bonded structure of solid acetamide ascribable to their small size, confinement effects, and acetamide-AOT head group interactions. The stretching modes of acetamide CO and AOT sulfonate groups indicate unambiguously specific acetamide-AOT head group interactions.
THE MAGNETIC SUSCEPTIBILITY OF MOLTEN NICKEL(II) COMPLEXES
1957
Abstract The bis-( N -alkylsalicylaldimine) - nickel (II) complexes, which are diamagnetic in the solid state, become paramagnetic with moments ranging from 0.8 to 1.15 B.M. in the molten state.
The comparative spreading behavior of enantiomeric and racemic tyrosine amphiphiles
1985
Several derivatives of tyrosine or its methyl ester have been synthesized in which the para hydroxyl group on the aromatic side chain has been converted to a long chain alkyl ether or urethane. The surface behavior of these compounds is discussed. Enantiomeric discrimination, the ability of a chiral molecule to distinguish between mirror-image stereoisomers, has been investigated for the urethane derivates by comparing the surface pressure-area isotherms of the enantiomer with that of the racemic compound. Enantiomeric discrimination was demonstrated for the methyl ester analog, but was not conclusively observed for the zwitterionic compounds. Possible structural requirements for enantiomer…
Orientation, recognition, and photoreaction of nucleolipids in model membranes
1990
Amphiphiles with nucleobases and nucleosides as headgroups have been synthesized. Their surface behavior was investigated in monolayers at the air/water interface. The double chain nucleolipids form stable monolayers with nearly identical surface pressure-area diagrams, whereas the spreading behavior of the mono chain amphiphiles is dominated by the various nucleobase-headgroups. When measuring the interactions between nucleolipid monolayers and nucleobases (monomeric and polymeric ones), specific base-base effects could be observed: the complementary nucleobases solubilized in the subphase expand the monolayer more than the non-complementary ones. Photodimerization reactions of thymine-amp…
Diffusion in concentrated colloidal suspensions and glasses
1998
The well established analogy between colloidal suspensions and atomic fluids has been extended to the glass transition problem in the past few years. Colloids have become the ideal test case for checking glass transition theories; this was due to the possibility of modeling hard spheres with colloidal dispersions. Significant progress has also been made in instrumentation, especially in the development of light-scattering techniques allowing moderately turbid and nonergodic samples to be analyzed. Mode coupling theory has become a paradigm not only for the glass transition, but also for the understanding of dynamics in highly concentrated colloidal dispersions where crystallization is suppr…