Search results for "Note"
showing 10 items of 10709 documents
Perovskite Solar Cells: Stable under Space Conditions
2020
Metal halide perovskite solar cells (PSCs) are of interest for high altitude and space applications due to their lightweight and versatile form factor. However, their resilience toward the particle spectrum encountered in space is still of concern. For space cells, the effect of these particles is condensed into an equivalent 1 MeV electron fluence. The effect of high doses of 1 MeV e-beam radiation up to an accumulated fluence to 10^16 e-cm-2 on methylammonium lead iodide perovskite thin films and solar cells is probed. By using substrate and encapsulation materials that are stable under the high energy e-beam radiation, its net effect on the perovskite film and solar cells can be studied.…
Calibration and Validation of Algorithms for the Estimation of Chlorophyll-A in Inland Waters with Sentinel-2
2018
The Ocean Color 2 (OC2), Ocean Color 3 (OC3) and Dall'Olmo three-band (TBDO) algorithms used for the estimation of the chlorophyll-a concentration [Chl-a] have been calibrated and validated for Sentinel-2 spectral bands. Measurements of in situ chlorophyll-a, radiometry and simulations with HydroLight have been used for this purpose within the Ecological Status of AQuatic Systems Satellites (ESAQS) Project to estimate water quality in aquatic systems in Spain. The results show that Sentinel-2 spectral bands are suitable for studying the chlorophyll-a concentration in inland waters. The TBDO algorithm have been applied to Sentinel-2 images and satisfactory results have been obtained in Albuf…
Proposal of Isobutyl Alcohol as Entrainer To Separate Mixtures Formed by Ethanol and Water and 1-Propanol and Water
2017
Isobutyl alcohol (IBA) has been proposed as a solvent to carry out the dehydration of ethanol and 1-propanol by means of a nonconventional distillation process. In this way, isobaric vapor–liquid equilibrium (VLE) and vapor–liquid–liquid equilibrium (VLLE) data at atmospheric pressure have been obtained for the ternary systems ethanol (1a) + water (2) + IBA (3) and 1-propanol (1b) + water (2) + IBA (3). Then, these data have been correlated to obtain a set of parameters capable of estimating VLE and VLLE. According to the results achieved, distillation sequences to separate water and ethanol or 1-propanol have been proposed. Finally, a study about the minimum amount of entrainer required to…
Colorimetric determination of alcohols in spirit drinks using a reversible solid sensor
2018
Abstract A sensor for the colorimetric estimation of the alcoholic content has been developed based on the entrapment of the reagent (4-N,N-dioctylamino)-4‘-trifluoroacetylazobenzene (ETHT 4001) into polydimethylsiloxane (PDMS) modified with tretraethylorthosilicate (TEOS). When exposed to an alcoholic media, the sensor delivers ETHT 4001 so that it reacts with alcohols, resulting in a change in the solution color. The diffusion of the entrapped ETHT 4001 from the polymeric sensor to the working solution depends on the hydrophobicity of both the sensor matrix and the media, while the time of exposure determines whether the reagent reacts with methanol, or with methanol and ethanol. Thus, th…
Opals infiltrated with a stimuli-responsive hydrogel for ethanol vapor sensing
2013
We report on a novel class of optical materials for ethanol vapor sensing, based on polystyrene opals infiltrated with an innovative stimuli responsive hydrogel. We describe the fabrication process of the bare polystyrene opals and their subsequent infiltration. The optical characterization of the photonic crystal templates was performed to prove the good quality of the samples. Measurements on the infiltrated opals showed that the transmission spectra in the visible range strongly change at varying concentrations of ethanol vapor. The fabricated structures show a linear optical response in the visible range, for high values of ethanol concentration.
Ligand-Binding Cooperativity Effects in Polymer-Protein Conjugation.
2019
We present an electron paramagnetic resonance (EPR) spectroscopic characterization of structural and dynamic effects that stem from post-translational modifications of bovine serum albumin (BSA), an established model system for polymer-protein conjugation. Beyond the typical drug delivery and biocompatibility aspect of such systems, we illustrate the causes that alter internal dynamics and therefore functionality in terms of ligand-binding to the BSA protein core. Uptake of the paramagnetic fatty acid derivative 16-doxyl stearic acid by several BSA-based squaric acid macroinitiators and polymer-protein conjugates was studied by EPR spectroscopy, aided by dynamic light scattering (DLS) and z…
“Dumb” pH-Independent and Biocompatible Hydrogels Formed by Copolymers of Long-Chain Alkyl Glycidyl Ethers and Ethylene Oxide
2020
The formation and rheological properties of hydrogels based on amphiphilic ABA triblock polyether copolymers are described, relying solely on the hydrophobic interaction of long-chain alkyl glycidyl ether (AlkGE)- based A-blocks that are combined with a hydrophilic poly(ethylene glycol) (PEG) midblock. Via anionic ring-opening copolymerization (AROP), ethylene oxide (EO) and long-chain alkyl glycidyl ethers (AlkGEs) were copolymerized, using deprotonated poly(ethylene glycol) (PEG) macroinitiators (Mn of 10, 20 kg mol-1). The polymerization afforded amphiphilic ABA triblock copolymers with molar masses in the range of 21-32 kg mol-1 and dispersities (Đ) of Đ = 1.07-1.17. Kinetic studies rev…
Convenient Access to α‐Amino‐ω‐Hydroxyl Heterobifunctional PEG and PPO via a Sacrificial Hexahydro‐Triazine Star Strategy
2019
The anionic ring opening polymerizations of ethylene oxide (EO) and propylene oxide (PO) are performed by using 1,3,5-triethanol hexahydro-1,3,5-triazine (TrAz) as a "sacrificial" trifunctional initiator. Well-defined three-arm star polymers are obtained with a narrow molecular weight distribution (M w /M n < 1.1). Molecular weights range from 3-15 kg mol-1 . Since these star polymers possess an acid-labile hexahydro-triazine core, acidic hydrolysis leads to cleavage of the arms. This gives access to well-defined α-amino-ω-hydroxyl heterobifunctional poly(ethylene glycol) (PEG) and poly(propylene oxide) (PPO) in the molecular weight range of 1-5 kg mol-1 and low dispersity M w /M n < 1.1. T…
Long-Chain Alkyl Epoxides and Glycidyl Ethers: An Underrated Class of Monomers.
2020
Long-chain epoxides and specifically alkyl glycidyl ethers represent a class of highly hydrophobic monomers for anionic ring-opening polymerization (AROP), resulting in apolar aliphatic polyethers. In contrast, poly(ethylene glycol) is known for its high solubility in water. The combination of hydrophobic and hydrophilic monomers in block and statistical copolymerization reactions enables the synthesis of amphiphilic polyethers for a wide range of purposes, utilizing micellar interactions in aqueous solutions, e.g., viscosity enhancement of aqueous solutions, formation of supramolecular hydrogels, or for polymeric surfactants. Controlled polymerization of these highly hydrophobic long-chain…
Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation.
2015
The review summarizes current trends and developments in the polymerization of alkylene oxides in the last two decades since 1995, with a particular focus on the most important epoxide monomers ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). Classical synthetic pathways, i.e., anionic polymerization, coordination polymerization, and cationic polymerization of epoxides (oxiranes), are briefly reviewed. The main focus of the review lies on more recent and in some cases metal-free methods for epoxide polymerization, i.e., the activated monomer strategy, the use of organocatalysts, such as N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) as well as phosphazen…