Search results for "Macro"
showing 10 items of 3471 documents
Riverine impacts on benthic biodiversity and functional traits: A comparison of two sub-Arctic fjords
2020
Abstract Climate change is leading to increases in freshwater discharge to coastal environments with implications for benthic community structure and functioning. Freshwater inputs create strong environmental gradients, which potentially affect the community structure of benthic infauna. In turn, changes in functional trait composition have the potential to affect the processing of terrestrially-derived nutrients and organic matter along the freshwater to marine continuum. We investigated the effects of riverine inputs on benthic community structure, functional traits, taxonomic and functional diversity, and utilization of terrestrial organic matter in two contrasting northern Norwegian fjo…
Selective recognition of aromatic hydrocarbons by endo-functionalized molecular tubes via C/N-H⋅⋅⋅π interactions
2018
Abstract Molecular recognition of aromatic hydrocarbons by four endo -functionalized molecular tubes has been studied by 1 H NMR spectroscopy, computational methods, and single crystal X-ray crystallography. The binding selectivity is rationalized by invoking shape complementarity and dipole alignment. The non-covalent interactions are proved to predominantly be C/N-H⋅⋅⋅ π interactions.
Methyl-Substituted α-Cyclodextrin as Affinity Material for Storage, Separation, and Detection of Trichlorofluoromethane
2018
Abstract The severely ozone‐depleting trichlorofluoromethane is still appearing in several recycling processes or industrial applications. A simple and selective supramolecular complex formation of per‐methylated α‐cyclodextrin (1) with the highly volatile trichlorofluoromethane (2) is reported. This interaction moreover leads to thermally stable crystals. Per‐methylated α‐cyclodextrin is successfully exploited as a reversible and selective adsorption material for liquid and airborne trichlorofluoromethane as well as an affinity material for the chemical sensing and detection of this particular volatile organic component.
Photooxidation and Stabilization of Photooxidized Polyethylene and of its Monopolymer Blends
2003
The increasing use of products from recycled polymers, or from blends with recycled polymers exposed to the outdoors, implies the need for good weathering resistance. This is particularly important when the recycled material comes, in turn, from products exposed during their lifetime to the sun. In this case the presence of C=O groups in the macromolecular chains strongly increases the photooxidative degradation kinetics of these secondary materials. In this work the change of the photooxidative degradation of blends of virgin and photooxidized polyethylene was evaluated as a function of the C=O content present in the material. As expected, the presence of the C=O groups strongly increases …
A Click Chemistry-Based “Grafting Through” Approach to the Synthesis of a Biorelevant Polymer Brush
2011
A new biorelevant polymer brush showing a polybenzofulvene backbone was synthesized by a ‘‘grafting through’’ approach based on click chemistry and spontaneous polymerization reactions. The easy polymerization of the relatively complex monomer (6-MOEG-9-TM-BF3k) suggests the existence of a particularly efficient recognition process capable of pre-organizing the monomer molecules for the spontaneous polymerization. 13C-NMR spectroscopy as well as UV-vis and fluorescence spectroscopy suggested for poly-6-MOEG-9-TM-BF3k the features of a vinyl (1,2) p-stacked polymer. The new polybenzofulvene derivative was found to interact with water at room temperature to give clear water solutions, but TEM…
Polymerization of methyl and phenyl oxazoline initiated with alkyl chloroformates
2010
It has been shown that alkyl chloroformates are capable of initiating the polymerization of oxazolines. Esters itself initiate rather slowly and the polymerization proceeds via covalent growing species. Exchange of counter ions with triflate or iodide anions leads to faster initiation and higher reaction rates. The polymerization is of living character.
Binding and Fluorescent Sensing of Dicarboxylates by a Bis(calix[4]pyrrole)-Substituted BODIPY Dye
2013
A bis(calix[4]pyrrole)-substituted BODIPY ditopic receptor 1 has been synthesised and characterised. The binding and sensing properties of 1 towards several aliphatic and aromatic dicarboxylates have been evaluated by using UV/Vis fluorescence and 1H NMR spectroscopy. The receptor strongly binds linear α,ω-dicarboxylates of appropriate lengths (C9 and C10) by acting as a cleft. For all dicarboxylates, the binding event is detected by a bathochromic shift in the UV/Vis spectra of the receptor and by strong quenching of its fluorescence.
Acrylic Graft Copolymers Via Macromonomers
1995
Comb-shaped poly(methyl methacrylate) (PMMA) and PMMA grafted with poly(nbutyl acrylate) (PnBuA) were prepared by radical copolymerisation of ω-methacryloyl-PMMA with MMA and nBuA, respectively. The comb-shaped PMMA is characterised with respect to radius of gyration by using GPC equipped with a multi-angle laser light scattering detector. The radical copolymerisation of the macromonomer with nBuA in toluene follows complex kinetics. The dependence of the relative reactivity of the macromonomer on absolute concentration and on the ratio of comonomers may be explained by preferential solvation of comonomers by segments of their own kind (“bootstrap effect”) or even micelle formation. However…
Pharmakologisch aktive polymere, 5. Modellreaktionen zur umsetzung von pharmaka und enzymen mit monomeren und polymeren reaktiven estern
1973
Die Darstellung reaktiver Ester der Acryl-, Methacryl- und N-Vinylcarbaminsaure wird beschrieben. Die Verbindungen sind im Gegensatz zu anderen reaktiven Saurederivaten wie Saurechloriden, -anhydriden und Isocyanaten kristalline Monomere, die gut zu handhaben sind. Sie lassen sich leicht zu unvernetzten, loslichen Polymeren homo- und copolymerisieren. Die Copolymerisationsparameter wurden bestimmt. Entsprechend wie die aus der Peptidchemie bekannten reaktiven Ester reagieren sie in monomerer wie in polymerer Form bei niedriger Temperatur selektiv und schonend mit Nucleophilen in guten Ausbeuten, z. B. mit Aminen in wasriger Losung. Dies eroffnet die Moglichkeit zur nebenreaktionsfreien Bind…
Effect of Monooxygenase Inducers on the Binding of Benzo-(A)Pyrene Metabolites to Cellular Macromolecules in Perfused Rat Lungs
1978
The irreversible binding of metabolically activated [3H]-benzo(a)pyrene (BP) to cellular macromolecules of isolated perfused rat lungs was studied. Lungs from differently pretreated animals were perfused in situ in a recirculating system without ventilation. BP with a specific activity of 10 mCi/μmol was added to 50 ml perfusion medium containing 40% washed bovine erythrocytes to a final concentration of 1 μM. DNA, RNA and protein fractions were isolated and assayed for irreversibly bound radioactivity.