Search results for "Solvent"
showing 10 items of 1395 documents
Species- and site-specific efficacy of commercial biocides and application solvents against lichens
2017
Abstract Control of lichens on stone cultural heritage is mostly achieved by a combination of mechanical removal with biocide applications. However, there is a lack of scientific evidence on the efficacy of different biocides on different species, and on the consistency of biocide effects on heritage sites in different environmental conditions. This results in some uncertainty when conservation interventions to control lichens are routinely defined on the basis of restoration tradition or empirical evaluation, without experimental measures of how lichens respond. In this work, we quantitatively evaluated (a) the efficacy of five commercially-available biocides, applied using a brush or with…
Optimization of antioxidants extraction from peanut skin to prevent oxidative processes during soybean oil storage
2017
8 páginas, 3 figuras, 2 tablas
A critical evaluation of Amicon Ultra centrifugal filters for separating proteins, drugs and nanoparticles in biosamples
2015
Amicon(®) Ultra centrifugal filters were critically evaluated for various sample preparations, namely (a) proteome fractionation, (b) sample cleanup prior to liquid chromatography mass spectrometry (LC-MS) measurement of small molecules in cell lysate, and (c) separating drug-loaded nanoparticles and released drugs for accurate release profiling in biological samples. (a) Filters of supposedly differing molar mass (MM) selectivity (10, 30, 50 and 100K) were combined to attempt fractionation of samples of various complexity and concentration. However, the products had surprisingly similar MM retentate/filtrate profiles, and the filters were unsuited for proteome fractionation. (b) Centrifuga…
Impact of ultrasound extraction parameters on the antioxidant properties of Moringa oleifera leaves
2020
Recently, much interest has been focused on Moringa oleifera L., a highly versatile and sustainable plant. In addition to its nutritional properties, numerous bioactive compounds have been identified in M. oleifera leaves, for which healthy properties have been reported. In the present research, the impact of ultrasound-assisted extraction (UAE) on the recovery of the bioactive compounds from leaves was investigated. Firstly, an experimental design approach has been used to highlight the influence of some extraction parameters (solvent, solvent/dry leaves ratio, temperature, time) on phenol compound recovery and antioxidant activity. Solvent composition was the most influential factor
The effect of organic solvents on selected microorganisms and model liposome membrane
2019
The effect of methanol, ethanol, acetone, N,N-dimethylformamide (DMF), dimethyl sulfoxide and Nujol on the growth of Escherichia coli DH5α, Bacillus subtilis and Saccharomyces cerevisiae D273 was investigated. All of the tested cultures appeared susceptible to the organic media they were treated with, which evinced in apparent hindering of cell development. The observed diverse solvent tolerance, except from their different biochemical activity, may also be related to the changes in cell membrane fluidity induced by the solvent species. Parallel electron paramagnetic resonance investigations using egg yolk lecithin model liposomes revealed that the fluidity of the phospholipid system in cel…
Synthesis and influence of fatty acid esters on the foliar penetration of herbicides
1998
Abstract Synthesis of mono-esters of tetraethylene glycol and di-esters of tetraethylene glycol was accomplished from fatty acids and tetraethylene glycol in the absence of solvent and catalyst. Esterification was studied in a batch reactor by using a response surface methodology to evaluate the influence of synthesis variables such as molar substrate ratio of fatty acid relative to tetraethylene glycol (1.39–7.52), temperature (145–167°C), reaction time (0.5–8 h) on the yield of mono- and di-esters of tetraethylene glycol. A multipurpose reactor was developed for the transformation of fatty acids into pure α-monoglycerides. The 1-monoglycerides of heptanoic, undecelenic, oleic, linoleic an…
Solvent dependence of the νs(OD) bandshape in 2,6-dichlorophenol
1994
Abstract The infrared bandshape of νs(OD) of 2,6-dichlorophenol is measured in a series of solvents of increasing polarity, and is quantitatively analysed. The bandshape is described in terms of band indices, moments, correlation functions and correlation times. A distinct solvent dependence of bandshape and relaxation parameters has been found. The changes of the νs(OD) bandshape with increasing solvent polarity are compared in detail with those obtained earlier for analogous solvents for νs(OH) of 2,6-dichlorophenol. The overall behaviour of the spectral and relaxation parameters is similar, but the changes are less distinct for the weaker OD ⋯ Cl bond.
PHEA-PLA biocompatible nanoparticles by technique of solvent evaporation from multiple emulsions
2015
Nanocarriers of amphiphilic polymeric materials represent versatile delivery systems for poorly water soluble drugs. In this work the technique of solvent evaporation from multiple emulsions was applied to produce nanovectors based on new amphiphilic copolymer, the α,β-poly(N-2-hydroxyethyl)-DL-aspartamide-polylactic acid (PHEA-PLA), purposely synthesized to be used in the controlled release of active molecules poorly soluble in water. To this aim an amphiphilic derivative of PHEA, a hydrophilic polymer, was synthesized by derivatization of the polymeric backbone with hydrophobic grafts of polylactic acid (PLA). The achieved copolymer was thus used to produce nanoparticles loaded with α toc…
PEG 400/Cerium Ammonium Nitrate Combined with Microwave-Assisted Synthesis for Rapid Access to Beta-Amino Ketones. An Easy-to-Use Protocol for Discov…
2018
Compound libraries are important requirement in target-based drug discovery. In the present work, a small focused compound library based on β-aminoketone scaffold has been prepared combining microwave-assisted organic synthesis (MAOS) with polymer-assisted solution phase synthesis (PASPS) and replacing reaction workup standard purification procedures with solid phase extraction (SPE). Specifically, the effects of solvent, such as dioxane, dimethylformamide (DMF), polyethylene glycol 400 (PEG 400), temperature, irradiation time, stoichiometric ratio of reagents, and catalysts (HCl, acetic acid, cerium ammonium nitrate (CAN)) were investigated to maximize both conversion and yield. The optimi…
Synthesis and characterization of sulfonamides containing 8-aminoquinoline and their Ni(II) complexes. Crystalline structures of the Ni complexes
2002
Reaction between 8-aminoquinoline and benzenesulfonyl, toluene-4-sulfonyl and naphthalene-2-sulfonyl chlorides in a basic medium leads to the formation of the corresponding sulfonamides. Reaction of these sulfonamides with Ni(II) salts leads to the formation of the corresponding complexes, with a NiL 2 stoichiometry. Determination of the crystalline structure by X-ray diffraction shows an octahedral environment for the Ni(II) ions, sulfonamides acting as bidentate ligands and two solvent molecules completing the octahedral coordination. The spectroscopic and magnetic properties of these compounds are also discussed.