Search results for "surface"
showing 10 items of 9345 documents
Crystal structure and Hirshfeld surface analysis of (Z)-4-chloro-N′-(4-oxothiazolidin-2-ylidene)benzenesulfonohydrazide monohydrate
2018
The asymmetric unit of the title thiazole derivative containing a sulfonylhydrazinic moiety, C9H8ClN3O3S2·H2O, consists of two independent molecules and two water molecules. The central parts of the molecules are twisted as both the molecules are bent at both the S and N atoms. In the crystal, N—H...N, N—H...O, C—H...O and O—H...O hydrogen-bonding interactions connect the molecules, forming layers parallel to the ab plane. Two-dimensional fingerprint plots associated with the Hirshfeld surface show that the largest contributions to the crystal packing come from O...H/H...O (32.9%) and H...H (22.6%) interactions.
Oxidation-responsive and "clickable" poly(ethylene glycol) via copolymerization of 2-(methylthio)ethyl glycidyl ether
2016
Poly(ethylene glycol) (PEG) is a widely used biocompatible polymer. We describe a novel epoxide monomer with methyl-thioether moiety, 2-(methylthio)ethyl glycidyl ether (MTEGE), which enables the synthesis of well-defined thioether-functional poly(ethylene glycol). Random and block mPEG-b-PMTEGE copolymers (Mw/Mn = 1.05-1.17) were obtained via anionic ring opening polymerization (AROP) with molecular weights ranging from 5 600 to 12 000 g·mol-1. The statistical copolymerization of MTEGE with ethylene oxide results in a random microstructure (rEO = 0.92 ± 0.02 and rMTEG E = 1.06 ± 0.02), which was confirmed by in situ 1H NMR kinetic studies. The random copolymers are thermorespon…
MODIFICATION OF HYDROPHOBIC SURFACE WITH POLYASPARTAMIDE-BASED POLYCATIONS FOR BIOMEDICAL APPLICATION
2013
A convenient way for the achievement of polymer-based solid materials for specific biomedical applications is grafting the appropriate macromolecules onto the surfaces in order to confer them specific properties. To date many approaches have been used to covalently modify polymeric surfaces, and among them chemoselective coupling reactions, usually referred as “click” reactions, gained much attention thanks to simple procedure with high reaction rate under mild reaction conditions (at normal temperature and pressure) [1]. In particular, radical-initiated thiol-yne “photo-click” chemistry has been demonstrated as an effective way to functionalize efficiently surfaces. This method gives also …
Calcium mediated polyelectrolyte adsorption on like-charged surfaces.
2011
International audience; Monte Carlo simulations within the primitive model of calcium-mediated adsorption of linear and comb polyelectrolytes onto like-charged surfaces are described, focusing on the effect of calcium and polyion concentrations as well as on the ion pairing between polymers and calcium ions. We use a combination of Monte Carlo simulations and experimental data from titration and calcium binding to quantify the ion pairing. The polymer adsorption is shown to occur as a result of surface overcharging by Ca2+ and ion pairing between charged monomers and Ca2+. In agreement with experimental observations, the simulations predict that the polymer adsorption isotherm goes through …
X-ray microtomography and laser ablation in the analysis of ink distribution in coated paper
2015
A novel method was developed for studying the ink-paper interface and the structural variations of a deposited layer of ink. Combining high-resolution x-ray tomography with laser ablation, the depth profile of ink (toner), i.e., its varying thickness, could be determined in a paper substrate. X-ray tomography was used to produce the 3D structure of paper with about 1 lm spatial resolution. Laser ablation combined with optical imaging was used to produce the 3D structure of the printed layer of ink on top of that paper with about 70 nm depth resolution. Ablation depth was calibrated with an optical profilometer. It can be concluded that a toner layer on a light-weight-coated paper substrate …
A New Spatial Shift‐Share Decomposition: An Application to Tourism Competitiveness in Italian Regions
2020
The paper proposes a new version of spatial shift-share decomposition to improve on the various approaches to conventional shift-share analysis found in the literature. The novelty of our proposal is that it enables researchers to assess spatial competitiveness effects controlling for the influence of industrial specialization at both regional and neighborhood level. This new version is applied to inbound tourism in Italian regions and enables us to identify the best and worst performers. Our empirical results identify favorable scenarios in some areas of the country, such as Sardinia as well as regional advantage in a sizeable number of well-known destinations.
Changes of total annual runoff distribution, high and low discharges in Latvian rivers
2009
Changes of total annual runoff distribution, high and low discharges in Latvian rivers The paper examines climate change impacts on the hydrological regime of nineteen different river basins in Latvia. Hydrological data series for the period of 1951-2006 were analysed for river basins of four hydrological districts: Western, Central, Northern and Eastern. Climate change has influenced the temporal and spatial distribution of total annual river runoff and high and low flows in Latvia at the turn of century. The results confirm the hypothesis that the main tendency in the run-off change is a decrease in spring floods and increase in winter. Generally, statistically insignificant long-term tre…
Synthesis, X-Ray Structure, Tautomerism Aspect, and Chemical Insight of The 3-(1H-Indol-2-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-ol
2021
The 3-(1H-indol-2-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-ol 2 was obtained exclusively in the enol configuration starting from triazolyl-indole derivative 1 and alkyl halo-esters in the presence of K2CO3. Chemical structure elucidations with the aid of physicochemical characterizations were used to predict its molecular structure while single crystal X-ray diffraction technique was used to shed the light on the supramolecular structure of 2. DFT calculations agreed very well with the reported X-ray structure where the most stable form thermodynamically is the enol form. Its optimized geometry agreed very well with the experimental structure where the correlation coefficients betwe…
Land surface temperature and evapotranspiration estimation in the Amazon evergreen forests using remote sensing data
2019
Amazonian tropical forests play a significant role in global water, carbon and energy cycles. Considering the relevance of this biome and the climate change projections which predict a hotter and drier climate for the region, the monitoring of the vegetation status of these forests becomes of significant importance. In this context, vegetation temperature and evapotranspiration (ET) can be considered as key variables. Vegetation temperature is directly linked with plant physiology. In addition, some studies have shown the existing relationship between this variable and the CO2 absorption capacity and biomass loss of these forests. Evapotranspiration resulting from the combined processes of …
The Aqua-Planet Experiment (APE): CONTROL SST Simulation
2013
Climate simulations by 16 atmospheric general circulation models (AGCMs) are compared on an aqua-planet, a water-covered Earth with prescribed sea surface temperature varying only in latitude. The idealised configuration is designed to expose differences in the circulation simulated by different models. Basic features of the aqua-planet climate are characterised by comparison with Earth. The models display a wide range of behaviour. The balanced component of the tropospheric mean flow, and mid-latitude eddy covariances subject to budget constraints, vary relatively little among the models. In contrast, differences in damping in the dynamical core strongly influence transient eddy amplitudes…