Search results for " Modification"
showing 10 items of 781 documents
Isotropic stochastic flow of homeomorphisms on Sd for the critical Sobolev exponent
2006
Abstract In this work, we shall deal with the critical Sobolev isotropic Brownian flows on the sphere S d . Based on previous works by O. Raimond and LeJan and Raimond (see [O. Raimond, Ann. Inst. H. Poincare 35 (1999) 313–354] and [Y. LeJan, O. Raimond, Ann. of Prob. 30 (2002) 826–873], we prove that the associated flows are flows of homeomorphisms.
N6 -Methyladenosine Modification in Chronic Stress Response Due to Social Hierarchy Positioning of Mice
2021
Appropriately responding to stressful events is essential for maintaining health and well-being of any organism. Concerning social stress, the response is not always as straightforward as reacting to physical stressors, e.g., extreme heat, and thus has to be balanced subtly. Particularly, regulatory mechanisms contributing to gaining resilience in the face of mild social stress are not fully deciphered yet. We employed an intrinsic social hierarchy stress paradigm in mice of both sexes to identify critical factors for potential coping strategies. While global transcriptomic changes could not be observed in male mice, several genes previously reported to be involved in synaptic plasticity, l…
Halloysite nanotubes as nanoreactors for heterogeneous micellar catalysis
2021
Abstract Hypothesis Electrostatic attractions between the anionic head group of sodium alkylsulphates and the positively charged inner surface of halloysite nanotubes (HNTs) drive to the formation of tubular inorganic micelles, which might be employed as nanoreactors for the confinement of non polar compounds in aqueous media. On this basis, sodium alkylsulphates/halloysite hybrids could be efficient nanocatalysts for organic reactions occurring in water. Experiments Sodium decylsulphate (NaDeS) and sodium dodecylsulphate (NaDS) were selected for the functionalization of the halloysite cavity. The composition, the structure and the surface charge properties of the hybrid nanotubes were dete…
Different Type Clay Amendments for Lead Immobilization in Contaminated Soils
2014
Contamination with lead in soil is a crucial problem in industrial and military sites. Immobilization of lead by natural and modified clay as soil amendment can be an effective solution to this problem. Quaternary and Devonian clays were chosen for modification with NaCl, CaCl2, FeOOH and Ca10(PO4)6(OH)2 in different proportions of Ca/P equimolar ratio to test and compare immobilization efficiency of lead (II) on raw and modified clays by using a batch leaching test. The aim of the study is to compare different types of raw and modified clays as soil amendments by lead immobilization properties.
ChemInform Abstract: Photochemical Functionalization of Allyl Benzoates by C-H Insertion.
2013
The photoreactivity of allyl benzoates, containing an electron-rich double bond, has been explored by irradiation at 305 nm in different solvents. Solvent addition products arising from an insertion of the alpha H–C bonds of THF, dioxane, and i-PrOH to the allylic double bond was realized. The observed reactivity depended on reaction conditions and substitution pattern of the substrate. A DFT study on this unusual reaction was performed allowing the formulation of two mechanistic pathways.
Utilisation of barium-modified analcime in sulphate removal: Isotherms, kinetics and thermodynamics studies
2017
Abstract Analcime and commercial zeolite were employed as a precursor for preparing sorbent material for SO42− removal over barium modification. Three sorbents were prepared: barium-modified analcime (ANA-Na-Ba), barium-modified acid-washed analcime (ANA-Ac-Na-Ba) and barium-modified zeolite (ZSM5-Na-Ba). Of the prepared materials, ANA-Ac-Na-Ba was the most efficient sorbent material for SO42− removal, with a maximum sorption uptake of 13.7 mg g−1 at room temperature. Batch sorption experiments were performed to evaluate the effect of initial pH, initial SO42− concentration, sorbent dosage, temperature and contact time of sorption. Several isotherms were applied to describe the experimental…
Reactive surface coatings based on polysilsesquioxanes: universal method toward light-responsive surfaces.
2011
Reactive surface coatings were used as an ideal precursor coating for the fabrication of three different photoswitchable surface coatings in parallel. Different light-responsive moieties, such as azobenzene, salicylideneaniline, and spiropyran, were immobilized on glass, polycarbonate, and steel surfaces. Independent from the underlying substrate, wettability could be switched reversibly by UV irradiation. The maximum switching range was obtained after functionalization of the reactive coating with spiropyran, resulting in a contact angle difference between the two isomeric states of almost 30°.
ChemInform Abstract: Synthesis and Functionalization of Chalcogenide Nanotubes
2011
New synthetic approaches to MS 2 (M = Sn, Nb, Mo, W) chalcogenide nanostructures are highlighted. Most chalcogenide particles can be functionalized directly with inorganic nanoparticles such as Au, ZnO or MnO. Depending on the Pearson hardness of the metal involved, the functionalization may be reversible or irreversible. A covalent functionalization strategy is based on a steric shielding of the coordination sphere of transition metal atoms in such a way that only coordination sites are available for bonding to the chalcogenide surface. This allows the immobilization of fluorophors, redox active groups or proteins onto chalcogenide nanoparticle.
DFT studies of COOH tip-functionalized zigzag and armchair single wall carbon nanotubes
2011
Structure and energy calculations of pristine and COOH-modified model single wall carbon nanotubes (SWCNTs) of different length were performed at B3LYP/6-31G* level of theory. From 1 to 9 COOH groups were added at the end of the nanotube. The differences in structure and energetics of partially and fully functionalized SWCNTs at one end of the nanotube are observed. Up to nine COOH groups could be added at one end of (9,0) zigzag SWCNT in case of full functionalization. However, for (5,5) armchair SWCNT, the full functionalization was impossible due to steric crowding and rim deformation. The dependence of substituent attachment energy on the number of substituents at the carbon nanotube ri…
Synthesis and functionalization of chalcogenide nanotubes
2010
New synthetic approaches to MS 2 (M = Sn, Nb, Mo, W) chalcogenide nanostructures are highlighted. Most chalcogenide particles can be functionalized directly with inorganic nanoparticles such as Au, ZnO or MnO. Depending on the Pearson hardness of the metal involved, the functionalization may be reversible or irreversible. A covalent functionalization strategy is based on a steric shielding of the coordination sphere of transition metal atoms in such a way that only coordination sites are available for bonding to the chalcogenide surface. This allows the immobilization of fluorophors, redox active groups or proteins onto chalcogenide nanoparticle.