Search results for " mixture"
showing 10 items of 1018 documents
Fast proton conduction in hydrogen bonded microheterogeneous systems: Bis(2-ethylhexyl)phosphoric acid/N-methyl formamide liquid mixtures
2009
Structural and dynamical properties of bis(2-ethylhexyl)phosphoric acid (HDEHP)/N-methyl formamide (NMF) liquid mixtures in the whole composition range have been investigated by Fourier Transform Infrared spectroscopy (FT-IR), X-rays Diffraction (XRD), and AC complex impedance spectroscopy. Driven by hydrogen bond interactions among HDEHP PO(4)H group and NMF CO and NH groups, and also by steric effects among the HDEHP alkyl chains, the system microstructure is mainly characterized by the coexistence of spatially separated hydrophilic and hydrophobic nanodomains showing local organization and short-range order. The evolution of this structural feature with system composition has been highli…
Decoupling of Dynamic Processes in Surfactant-Based Liquid Mixtures: The Case of Lithium-Containing Bis(2- ethylhexyl)phosphoric Acid/Bis(2-ethylhexy…
2014
Pure surfactant liquids and their binary mixtures, because of the amphiphilic nature of the molecules involved, can exhibit nanosegregation and peculiar transport properties. The idea that inspired this work is that the possibility of including in such media salts currently used for technological applications should lead to a synergy between the properties of the salt and those of the medium. Therefore, the dynamic features of bis(2-ethylhexyl)amine (BEEA) and bis(2-ethylhexyl)phosphoric acid (HDEHP) liquid mixtures were investigated as a function of composition and temperature by (1)H nuclear magnetic resonance (NMR) spectroscopy and rheometry. Inclusion of litium trifluoromethanesulfonate…
2-(4-Fluorophenyl)-1-(4-pyridyl)cyclopentan-1-ol
2007
The crystal structure of the title compound, C16H16FNO, was determined as part of a study of the biological activity of pyridine-substituted cyclopentene derivatives as p38 mitogen-activated protein kinase (MAPK) inhibitors. The 4-fluorophenyl and 4-pyridyl rings are trans positioned with respect to each other. The compound exists as a racemic mixture. The synthesis was achieved via direct interaction between the reactive complex Grignard reagent PyMgCl·LiCl and the enolizable ketone 4-fluorophenylcyclopentanone with the assistance of the neodymium salt catalyst NdCl3·2LiCl. The crystal packing is characterized by zigzag chains of molecules, which are connected by O—H⋯N hydrogen bon…
Stereospecific CC-bond formation with rabbit muscle aldolase - A chemoenzymatic synthesis of (+)-exo-brevicomin
1990
Abstract (+)-(1S,5R,7S)-Exo-brevicomin 9, a sex pheromone of the western pine bark beetle, is synthesized using an aldol reaction catalyzed by fructose-1,6-diphosphate aldolase (EC 4.1.2.13) from rabbit muscle as the key step by which the absolute configuration of the target is established.
Effect of over the counter mouthwashes with and without alcohol on sorption and solubility of bulk fill resins
2020
Background Composites sorption and solubility can be precursors of several chemical and physical processes, which lead to deleterious effects on the polymer structure. This study evaluated the effect of mouthwashes with and without alcohol on the sorption and solubility of conventional and low viscosity bulk fill resins. Material and Methods Four types of Bulk Fill resins (Filtek™ Bulk Fill, X-tra Fil, Filtek™ Bulk Fill Flow and X-tra Base) were submitted to the following mouthwashes: Listerine Cool Mint and Periogard (containing alcohol) and Listerine Zero and Periogard (alcohol-free). The specimens were stored in the mouthwashes for seven days. Solubility and sorption tests were performed…
Stereoselective synthesis and properties of 1,3-bis(dicyanomethylidene)indane-5-carboxylic acid acceptor fragment containing nonlinear optical chromo…
2016
A series of organic push–pull type chromophores using indane-1,3-dione 5-carboxylic acid (IDCA) and novel 1,3-bis(dicyanomethylidene)indane 5-carboxylic acid (CICA) electron acceptor fragments have been synthesized and characterized. NMR and X-ray analysis revealed that condensation reactions with the CICA fragment were stereoselective and yielded benzylidenes and azomethines with E double bond configurations. Due to the non-planar geometry these compounds are chiral and were acquired as a racemic mixture. The subsequent functionalization of the carboxylic acid group with 5,5,5-triphenylpentan-1-ol yielded solution-processable glass forming materials (6, 8, 10, 13) with glass transition tem…
Influence of Bacteria <i>Pseudomonas fluorescens</i> on the Properties of Latvian Clay
2014
Wide varieties of bacteria are able to produce extracellular polymeric substances (EPS) which are mostly composed of polysaccharides. It is suggested that EPS substances can alter certain clay soil properties due to their ability to adhere to the surface of mineral particles. Most common used microorganisms by the researchers for this purpose are of either genus Bacillus or genus Pseudomonas. In this study growth of bacteria P. fluorescens AM PS11 culture in locally obtained clay is studied for the purpose of establishing their influence on rheological properties of clay. An attempt to evaluate it has been made using FT-IR and XRD. Change in plasticity of clay using Atterberg limits method …
Spatial and short-term temporal variations in runoff, soil aggregation and other soil properties along a Mediterranean Climatological Gradient.
1998
Abstract Physical and chemical soil properties were measured along a mountainous climatological gradient in the province of Alicante (Spain). The objective was to evaluate how the climate affects certain soil properties at different temporal and spatial scales. These properties include infiltration, runoff and sediment concentrations resulting from rainfall simulation experiments performed in winter and in summer. Chemical soil properties like carbonate content, organic matter content and CEC were analysed in reference soil profiles along the gradient. Physical soil properties like soil moisture content, macroaggregation and waterstable microaggregation were measured at monthly intervals du…
Synthesis and Characterization of the Hybrid Clay-Based Material Montmorillonite-Melanoidin: A Potential Soil Model
2010
The study of the interactions among metals, minerals, and humic substances is essential in understanding the migration of inorganic pollutants in the geosphere. A considerable amount of organic matter in the environment is associated with clay minerals. To understand the role of organic matter in the environment and its association with clay minerals, a hybrid clay-based material (HCM), montmorillonite (STx-1)-melanoidin, was prepared from L-tyrosine and L-glutamic acid by the Maillard reaction. The HCM was characterized by elemental analysis, nuclear magnetic resonance, x-ray photoelectron spectroscopy (XPS), scanning transmission x-ray microscopy (STXM), and thermal analysis. The presence…
FORMATION OF A SMALL RIBONUCLEOPROTEIN PARTICLE BETWEEN TAT PROTEIN AND TRANS-ACTING RESPONSE ELEMENT IN HUMAN IMMUNODEFICIENCY VIRUS-INFECTED CELLS
1991
The trans-acting response element (TAR) within the long terminal repeat of human immunodeficiency virus (HIV) is present in all 5' termini of HIV mRNAs and is recognized by the viral Tat protein. Now we describe that the 59-nucleotide-long TAR-RNA exists as a ribonucleoprotein particle in polysomal and heterogeneous nuclear RNP fractions of HIV-1-infected HeLa-T4+ cells. Applying an immunoprecipitation technique this Tat.TAR complex could be isolated from total cell extracts as well as from polysomal or heterogeneous nuclear RNP fractions. The chain length and the identity of the TAR-RNA were established by RNase protection assays while the Tat protein was confirmed by Western blotting tech…