Search results for " modifica"
showing 10 items of 817 documents
Easy Route to Functionalize Iron Oxide Nanoparticles via Long-Term Stable Thiol Groups
2009
International audience; The functionalization of superparamagnetic iron oxide nanoparticles (SPIOs) by meso-2,3-dimercaptosuccinic acid (DMSA) was investigated. Under ambient conditions, the thiol groups from DMSA are not stable and do not allow a direct functionalization without storage in stringent conditions or a chemical regeneration of free thiols. In this study, we have developed a protocol based on poly(ethylene glycol) (PEG) grafting of SPIO prior to DMSA anchoring. We have observed that PEG helps to increase the stability of thiol groups under ambient conditions. The thiol functionalized SPIOs were stable under physiological pH and ionic strength as determined by Ellman's essay and…
Size and Surface Chemistry Tuning of Silicon Carbide Nanoparticles.
2017
International audience; Chemical transformations on the surface of commercially available 3C-SiC nanoparticles were studied by means of FTIR, XPS, and temperature-programmed desorption mass spectrometry methods. Thermal oxidation of SiC NPs resulted in the formation of a hydroxylated SiO2 surface layer with C3Si–H and CHx groups over the SiO2/SiC interface. Controllable oxidation followed by oxide dissolution in HF or KOH solution allowed the SiC NPs size tuning from 17 to 9 nm. Oxide-free SiC surfaces, terminated by hydroxyls and C3Si–H groups, can be efficiently functionalized by alkenes under thermal or photochemical initiation. Treatment of SiC NPs by HF/HNO3 mixture produces a carbon-e…
Quantifying the Covalent Functionalization of Black Phosphorus
2020
Abstract A straightforward quantification method to consistently determine the overall functionalization degree of covalently modified two‐dimensional (2D) black phosphorus (BP) by Raman spectroscopy has been carried out. Indeed, the successful reductive methylation of the BP lattice using sodium intercalation compounds and exhibiting different functionalization degrees has been demonstrated by 31P‐magic angle spinning (MAS) NMR spectroscopy. Furthermore, the correlation of 31P‐MAS NMR spectroscopy and statistical Raman spectroscopy (SRS) revealed the first method to determine the functionalization degree of BP solely by evaluating the intensities of distinct peaks in the Raman spectra of t…
Eukaryotic snoRNAs: a paradigm for gene expression flexibility.
2009
AbstractSmall nucleolar RNAs (snoRNAs) are one of the most ancient and numerous families of non-protein-coding RNAs (ncRNAs). The main function of snoRNAs – to guide site-specific rRNA modification – is the same in Archaea and all eukaryotic lineages. In contrast, as revealed by recent genomic and RNomic studies, their genomic organization and expression strategies are the most varied. Seemingly snoRNA coding units have adopted, in the course of evolution, all the possible ways of being transcribed, thus providing a unique paradigm of gene expression flexibility. By focusing on representative fungal, plant and animal genomes, we review here all the documented types of snoRNA gene organizati…
Equilibrio fra poteri e libertà dai Trattati in diritto dell'Unione europea e diritto internazionale
2014
Riflessione sulla categoria civilistica dell'invalidità applicata ai Trattati internazionali e a quella peculiare species costituita dai Trattati istitutivi dell'Unione Europea. Si dà conto altresì delle modalità di modifica degli stessi e dell'estinzione.
HALE-IoT: HArdening LEgacy Internet-of-Things devices by retrofitting defensive firmware modifications and implants
2022
Internet-Of-Things (IoT) devices and their firmware are notorious for their lifelong vulnerabilities. As device infection increases, vendors also fail to release patches at a competitive pace. Despite security in IoT being an active area of research, prior work has mainly focused on vulnerability detection and exploitation, threat modelling, and protocol security. However, these methods are ineffective in preventing attacks against legacy and End-Of-Life devices that are already vulnerable. Current research mainly focuses on implementing and demonstrating the potential of malicious modifications. Hardening emerges as an effective solution to provide IoT devices with an additional layer of d…
Endfunctional Polymers by Functionalization of Living Cationic Chain Ends with 1,1-Diphenylethylene
1995
Abstract A new functionalization method has been developed for the synthesis of 2,2-diphenylvinyl(DPV)-telechelic polyisobutylene (PIB). First, living carbocationic polymerization (LCCP) of isobutylene (IB) is quantitatively end-quenched with a nonpolymerizable olefin, 1,1-diphenylethylene (DPE). This process yields a mixture of diphenyl substituted vinyl and tertiary chlorine endgroups. Treatment of the resulting polymer with potassium-tert-butoxide (tBuOK) leads to the quantitative formation of DPV-telechelic PIB which is a potential macroinitiator precursor for living anionic polymerizations.
Rapid and Complete Surface Modification with Strain-Promoted Oxidation-Controlled Cyclooctyne-1,2-Quinone Cycloaddition (SPOCQ)
2017
Abstract Strain‐promoted oxidation‐controlled cyclooctyne‐1,2‐quinone cycloaddition (SPOCQ) between functionalized bicyclo[6.1.0]non‐4‐yne (BCN) and surface‐bound quinones revealed an unprecedented 100 % conjugation efficiency. In addition, monitoring by direct analysis in real time mass spectrometry (DART‐MS) revealed the underlying kinetics and activation parameters of this immobilization process in dependence on its microenvironment.
Strain-Promoted Cycloaddition of Cyclopropenes with o-Quinones : A Rapid Click Reaction
2018
Abstract Novel click reactions are of continued interest in fields as diverse as bio‐conjugation, polymer science and surface chemistry. Qualification as a proper “click” reaction requires stringent criteria, including fast kinetics and high conversion, to be met. Herein, we report a novel strain‐promoted cycloaddition between cyclopropenes and o‐quinones in solution and on a surface. We demonstrate the “click character” of the reaction in solution and on surfaces for both monolayer and polymer brush functionalization.
Synthesis, characterization and study of covalently modified triazole LAPONITE® edges
2020
Abstract LAPONITE® (Lap) clay mineral was successful functionalized by triazole groups in a two steps procedure. First, the Lap edges were modified with 3-azidopropyltrimethoxysilane by traditional heating and microwave irradiation. Microwave irradiation allowed us to obtain high loading onto the Lap edges in lower times compared to those obtained through conventional method. Afterwards, the triazole moieties were obtained by reaction between azido functionalized Lap and propargyl alcohol. The successful functionalization of Lap was proved by thermogravimetric analysis, FT-IR spectroscopy, dynamic light scattering and ζ-potential measurements. Finally, the effects of the surface modificatio…