Bibliografías temáticas / Nonpolar solvents

Literatura académica sobre el tema "Nonpolar solvents"

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Publicado: 18 de mayo de 2024

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Artículos de revistas sobre el tema "Nonpolar solvents"

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Roy, J. L. y W. B. McGill. "Flexible conformation in organic matter coatings: An hypothesis about soil water repellency". Canadian Journal of Soil Science 80, n.º 1 (1 de febrero de 2000): 143–52. http://dx.doi.org/10.4141/s98-093.

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Some soils develop severe water repellency several years or decades following oil contamination. We previously reported that soil water repellency is completely eliminated by extraction with amphiphilic solvents, but barely reduced by extraction with nonpolar solvents. We report here on solvent-induced reversible soil water repellency. Our results indicate that: (i) water repellency is completely eliminated following extraction with amphiphilic solvent, but partially restored following subsequent exposure to nonpolar, non-H-bonding solvent; (ii) extraction with nonpolar, non-H-bonding solvent generates water repellency in readily wettable control wettable soils, but not in pristine wettable soils, and (iii) repeated sequential extractions alternating between amphiphilic and nonpolar, non-H-bonding solvent increase extractable material and reduce the magnitude of solvent-induced soil water repellency with time.We attribute reversible soil water repellency to solvent-induced changes in the conformation of causative agents of soil water repellency. Recent literature reports on the structural flexibility of "insoluble" organic macromolecules are discussed for supporting evidence. We propose that exposure to nonpolar, non-H-bonding solvents induces stretching of surface-exposed, nonpolar moieties (i.e. alkyl chains), whereas exposure to polar, H-bonding solvents induces their coiling. These solvent-induced conformational changes are retained upon solvent removal. Our results indicate that the wettability of oil-contaminated soils depends on both the interfacial conformation and the fractional coverage of their surface-exposed nonpolar moieties. Key words: Soil water repellency, crude oil, hydrophobic soil, conformational flexibility, swelling, solvents
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2

Saita, Satoshi, Shin-ichi Takeda y Hideya Kawasaki. "Hansen Solubility Parameter Analysis on Dispersion of Oleylamine-Capped Silver Nanoinks and their Sintered Film Morphology". Nanomaterials 12, n.º 12 (10 de junio de 2022): 2004. http://dx.doi.org/10.3390/nano12122004.

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Optimizing stabilizers and solvents is crucial for obtaining highly dispersed nanoparticle inks. Generally, nonpolar (hydrophobic) ligand-stabilized nanoparticles show superior dispersibility in nonpolar solvents, whereas polar ligand (hydrophilic)-stabilized nanoparticles exhibit high dispersibility in polar solvents. However, these properties are too qualitative to select optimum stabilizers and solvents for stable nanoparticle inks, and researchers often rely on their experiences. This study presents a Hansen solubility parameter (HSP)-based analysis of the dispersibility of oleylamine-capped silver nanoparticle (OAm-Ag NP) inks for optimizing ink preparation. We determined the HSP sphere of the OAm-Ag NPs, defined as the center coordinate, and the interaction radius in 3D HSP space. The solvent’s HSP inside the HSP sphere causes high dispersibility of the OAm-Ag NPs in the solvent. In contrast, the HSPs outside the sphere resulted in low dispersibility in the solvent. Thus, we can quantitatively predict the dispersibility of the OAm-Ag NPs in a given solvent using the HSP approach. Moreover, the HSP sphere method can establish a correlation between the dispersibility of the particles in inks and the sintered film morphology, facilitating electronic application of the nanoparticle inks. The HSP method is also helpful for optimizing stabilizers and solvents for stable nanoparticle inks in printed electronics.
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Pytela, Oldřich. "A new classification of solvents based on chemometric empirical scale of parameters". Collection of Czechoslovak Chemical Communications 55, n.º 3 (1990): 644–52. http://dx.doi.org/10.1135/cccc19900644.

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The paper presents a classification of 51 solvents based on clustering in three-dimensional space formed by the empirical scale of PAC, PBC, and PPC parameters designed for interpretation of solvent effect on a model with cross-terms. For the classification used are the clustering methods of the nearest neighbour, of the furthest neighbour, of average bond, and the centroid method. As a result, the solvents have been divided into 8 classes denoted as: I - nonpolar-inert solvents (aliphatic hydrocarbons), IIp - nonpolar-polarizable (aromatic hydrocarbons, tetrachloromethane, carbon disulphide), IIb - nonpolar-basic (ethers, triethylamine), IIIp - little polar-polarizable (aliphatic halogen derivatives, substituted benzenes with heteroatom-containing substituents), IIIb - little polar-basic (cyclic ethers, ketones, esters, pyridine), IVa - polar-aprotic (acetanhydride, dialkylamides, acetonitrile, nitromethane, dimethyl sulfoxide, sulfolane), IVp - polar-protic (alcohols, acetic acid), and V - exceptional solvents (water, formamide, glycol, hexamethylphosphoric triamide). The information content of the individual parameters used for the classification has been determined. The classification is based primarily on solvent polarity/acidity (PAC), less on polarity/basicity (PBC), and the least on polarity/polarizability (PPC). Causal relation between chemical structure of solvent and its effect on the process taking place therein has been established.
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4

Suljkanović, Mersiha, Jasmin Suljagić, Edita Bjelić, Ante Prkić y Perica Bošković. "Chemical Characterization of Terpene-Based Hydrophobic Eutectic Solvents and Their Application for Pb(II) Complexation during Solvent Extraction Procedure". Molecules 29, n.º 9 (3 de mayo de 2024): 2122. http://dx.doi.org/10.3390/molecules29092122.

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Solvents prepared from natural terpenes (menthol and thymol), as H-bond acceptors, and a series of organic acids (chain lengths of 8, 10, and 14 C atoms), as H-bond donors, were characterized and tested as reaction media for liquid–liquid extraction purposes. Due to their high hydrophobicity, they seem to be promising alternatives to conventional (nonpolar and toxic) solvents, since they possess relatively less toxic, less volatile, and consequently, more environmentally friendly characteristics. Assuming that the equilibrium is established between solvent and analyte during a ligandless procedure, it can be concluded that those nonpolar solvents can efficiently extract nonpolar analytes from the aqueous environment. Previous investigations showed a wide range of applications, including their use as solvents in extractions of metal cations, small molecules, and bioactive compounds for food and pharmaceutical applications. In this work, hydrophobic solvents based on natural terpenes, which showed chemical stability and desirable physicochemical and thermal properties, were chosen as potential reaction media in the liquid–liquid extraction (LLE) procedure for Pb(II) removal from aqueous solutions. Low viscosities and high hydrophobicities of prepared solvents were confirmed as desirable properties for their application. Extraction parameters were optimized, and chosen solvents were applied. The results showed satisfactory extraction efficiencies in simple and fast procedures, followed by low solvent consumption. The best results (98%) were obtained by the thymol-based solvent, thymol–decanoic acid (Thy-DecA) 1:1, followed by L-menthol-based solvents: menthol–octanoic acid (Men-OctA) 1:1 with 97% and menthol–decanoic acid (Men-DecA) 1:1 with 94.3% efficiency.
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Al Mohaimeed, Rawabi M., Anees A. Ansari y Abdullah Aldwayyan. "The Role of Solvent Environment on the Optical Behavior of Chemically Synthesized Silicon Nanoparticles". Journal of Spectroscopy 2018 (2018): 1–9. http://dx.doi.org/10.1155/2018/6870645.

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Silicon nanoparticles (Si-NPs) were prepared by solution-based chemical etching method. Optical characteristics of the as-prepared Si-NPs were investigated in different polar and nonpolar organic solvents. The emission and absorption properties of Si-NPs were tuned by altering the environment (solvents). The variation in absorption coefficient was observed because of the solvent interaction nature of Si-NPs. Si-NPs in polar aprotic and nonpolar solvents manifested good luminescence under UV excitation. PL intensities were observed to be depending on etched cross-section area on wafer surface. The results show a linear dependence of the refractive index (n) on wavelength (λ). The nature of solvents altered the luminescence efficiency of Si-NPs when examining under UV lamp. The emission and absorption properties of Si-NPs were tuned by altering the environment (solvents) through electrostatic interaction of various organic solvents with the Si-NPs. The band shapes of the Si-NPs show remarkable changes in passing from noncoordinating solvent (chloroform) to various coordinating solvents, which was the result of change in the environment around Si-NPs in various solutions.
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Ghosh, Rajib, Amitabha Nandi y Dipak K. Palit. "Solvent sensitive intramolecular charge transfer dynamics in the excited states of 4-N,N-dimethylamino-4′-nitrobiphenyl". Physical Chemistry Chemical Physics 18, n.º 11 (2016): 7661–71. http://dx.doi.org/10.1039/c5cp07778h.

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Solvent sensitive excited state dynamics of DNBP is explored. In polar solvents, the ultrafast barrierless TICT process is the major relaxation pathway, whereas, in nonpolar solvents the excited state undergoes the PICT process, followed by efficient intersystem crossing to the triplet state.
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Werst, D. W. "Solvent effects in nonpolar solvents: Radical anion reactions". Chemical Physics Letters 202, n.º 1-2 (1993): 101–7. http://dx.doi.org/10.1016/0009-2614(93)85357-t.

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Wu, Xiaoli, Xulin Cui, Qi Wang, Jingtao Wang, Wenjia Wu, Wenpeng Li y Zhongyi Jiang. "Manipulating the cross-layer channels in g-C3N4 nanosheet membranes for enhanced molecular transport". Journal of Materials Chemistry A 9, n.º 7 (2021): 4193–202. http://dx.doi.org/10.1039/d0ta10236a.

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Cross-layer channels display ‘gate effect’ to govern molecular selectivity for lamellar membranes. Membranes with hydrophilic/hydrophobic heterostructured channels acquire elevated polar solvent permeance and polar/nonpolar solvents selectivity.
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9

Kovalenko, G. A. y L. V. Perminova. "Heterogeneous Biocatalytic Processes of the Low-Temperature Synthesis of Esters: Selection of Organic Solvent". Kataliz v promyshlennosti 20, n.º 4 (20 de julio de 2020): 313–22. http://dx.doi.org/10.18412/1816-0387-2020-4-313-322.

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Processes of the low-temperature enzymatic synthesis of esters in nonaqueous media of organic solvents with participation of heterogeneous biocatalysts synthesized by the adsorption immobilization of a recombinant lipase from Thermomyces lanuginosus (Pichia pastoris producer) on macroporous carbon aerogel were investigated. The esterification reaction was conducted using individual organic solvents of different polarity, such as nonpolar ones (lоgP > 2.5) – hexadecane, hexane and toluene, and polar solvents (lоgP < 1) – diethyl ether, tert-butanol and acetone, as well as their binary mixtures of different composition, for example, a mixture of hexane with diethyl ether having the composition 1 : (1/5÷3, vol. fr.). The effect of the solvent and co-solvent nature on the properties of synthesized biocatalysts, namely the enzymatic activity and operational stability, was studied in the batch esterification of heptanoic acid (C7:0) by alcohols, particularly the polar substrates – ethanol and n-butanol, or nonpolar alcohols – n-octanol and n-hexadecanol. Activity of the synthesized biocatalysts was found to depend to a great extent on polarity of both the solvents used in the reaction and the alcohol substrates. The maximum activity of 400 EA·g–1 was observed in a medium of nonpolar and nonviscous hexane (lоgP = 2.9), whereas the minimum activity of 4 EA·g–1 – in acetone (lоgP = 0.4); esterification of heptanoic acid in the presence of tert-butanol (lоgP = 0.6) virtually did not proceed. The activity of biocatalysts was shown to depend nonmonotonically on the lоgP value of individual solvent. In the binary mixtures of organic solvents, such as hexane/diethyl ether, biocatalytic activity linearly increased with an increase in lоgPmixture; in addition, biocatalysts exhibited the maximum operational stability.
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10

Siplivy, Nickolay y Anatoly Ivanov. "Features of the Electronic Structure of Excited Quadrupolar Molecules in Non-Polar Solvents". Mathematical Physics and Computer Simulation, n.º 2 (julio de 2021): 68–84. http://dx.doi.org/10.15688/mpcm.jvolsu.2021.2.6.

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Interactions of the electronic subsystem of the quadrupolar fluorophore with intramolecular highfrequency antisymmetric vibrations and solvent polarization are responsible for charge transfer symmetry breaking (SB), which is observed after optical excitation of such molecules in polar solvents. It is known that although these two interactions are mathematically described in similar ways, only the interaction of the fluorophore with solvent orientational polarization can create a state with broken symmetry if this interaction is strong enough. Nevertheless, the interaction of a quadrupolar fluorophore with intramolecular highfrequency antisymmetric vibrations in nonpolar solvents leads to a considerable reconstruction of the electronic subsystem. The analysis of the excited state of quadrupolar molecules in nonpolar solvents performed in this study reveals that such molecules can behave like quantum twostate systems, that is, as a quasispin s = 1/2, having an electric dipole moment instead of a magnetic one. This feature of excited quadrupolar molecules may be of interest to emerging technologies of molecular electronics.
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Tesis sobre el tema "Nonpolar solvents"

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Smith, Gregory N. "Charging colloids in nonpolar solvents". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683919.

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Stabilizing charged species in nonpolar solvents is difficult due to their low relative permittivity (Er); therefore, surfactants that form inverse micelles are often used as charge control additives (CCAs). In this Thesis, the structural and electrokinetic properties of surfactants and surfactant-charged colloids in nonpolar solvents were studied. The aggregation of surfactants was studied using high-resolution small-angle neutron scattering (SANS) measurements. Critical micelle concentrations (CMCs) for inverse micelle formation were measured for an anionic and a nonionic surfactant, and the transition was different for the two types. However, variations to the surfactant counterion and the solvent did not influence the CMC. Contrast-variation SANS (CV-SANS) was used to study the interaction of surfactant with polymer latexes. The surfactant did not strongly interact with the steric stabilizer polymer and, rather, was located throughout the entire latex. Such a distribution of surfactant differs from other model colloids in nonaqueous solvents where the surfactant is assumed to be adsorbed at the core-solvent interface. Molecular variations to the surfactant structure resulted in differences to the charge of particles. Modifying the surfactant tail groups resulted in more effective CCAs. Triple-chain surfactants were more effective, and this may be due to the larger number of inverse micelles. Changing the surfactant counterion resulted in instability of the particles. This may be due to decreased particle charge and increased electrolyte screening. The results presented in this Thesis provide much-needed structural information and systematic variations to the field of charging in nonpolar solvents. Determining the chemical interactions between surfactants and solvents or colloids is important for understanding how surfactants form inverse micelles, stabilize particles, and generate charge.
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2

Ghosh, Nilanjan. "Structural and associational aspects of some dielectropolar liquid molecules in non polar solvents from relaxation phenomena". Thesis, University of North Bengal, 2002. http://hdl.handle.net/123456789/670.

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Lin, Tina. "Dynamics of Charged Colloids in Nonpolar Solvents". Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11005.

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Charging is typically not expected in nonpolar environments due to a high electrostatic barrier to charge dissociation. Nevertheless, charge effects are observed in such environments upon the addition of surfactants, which aggregate to form charge-stabilizing reverse micelles. Surfactants facilitate the charging and electrostatic stabilization of particles dispersed in nonpolar solvents. Suspensions of charged particles in nonpolar solvents are found in a variety of applications, such as electrophoretic displays, in which charged pigment particles are arranged with an external electric field to form an image. The ability to precisely control the locations and trajectories of the particles using an electric field is essential. However, the behavior of charged particles in a nonpolar solvent in response to an electric field is not fully understood. To investigate the behavior of charged particles in nonpolar solvents, we fabricate a novel microfluidic device that allows us to apply an electric field across a particle suspension and directly visualize the particles as they move across a channel. We image the particles, analyze the particle dynamics, and explore the relationship between the dynamics and the electrical properties of the suspension. We find that the presence of reverse micelles has a significant effect on particle motion. In a constant applied electric field, the particles initially move, but then unexpectedly slow down and stop. This behavior is due to screening of the applied field by the accumulation of charged reverse micelles at the channel walls. Consequently, the internal electric field within the channel decays exponentially. The decay time constant is dependent on the electrical conductivity of the suspension and the size of the channel. We model this behavior as an equivalent RC circuit. We also explore the behavior of charged particles in applied fields that are large enough to transport the particles completely across the channel. We find that the transport of particles is governed by a fingering instability. Furthermore, repeated switches of the direction of the field results in the localization of particles into a well-defined, periodic pattern. The wavelength of this pattern is dependent on the frequency of the applied field.
Physics
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4

Mutihac, Radu-Christian. "Influence of polar solvents upon the complex formation between crown ethers and cations in nonpolar medium". [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=985279761.

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Karmakar, Achintya. "Dispersion and absorption phenomena of dipolar liquid in nonpolar solvent". Thesis, University of North Bengal, 2007. http://hdl.handle.net/123456789/662.

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Cox, Kerry James. "The distribution of conformers in some ortho and meta-substituted benzaldehydes in polar and nonpolar solvents". 1990. http://hdl.handle.net/1993/17023.

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Mutihac, Radu-Christian [Verfasser]. "Influence of polar solvents upon the complex formation between crown ethers and cations in nonpolar medium / presented by Radu-Christian Mutihac". 2007. http://d-nb.info/985279761/34.

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Capítulos de libros sobre el tema "Nonpolar solvents"

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Gooch, Jan W. "Nonpolar Solvents". En Encyclopedic Dictionary of Polymers, 489. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_7962.

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Maitra, Amarnath. "Amphiphilicity of Aerosol OT in Nonpolar Solvents". En Surfactants in Solution, 591–99. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4615-7981-6_3.

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Bodycomb, J. y M. Hara. "Scattering Studies of Ionomer Aggregates in Nonpolar Solvents". En Macromolecular Complexes in Chemistry and Biology, 347–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78469-9_20.

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Zhou, Xiaobing, Sanlin Hu, Nick E. Shephard y Dongchan Ahn. "Diffusion-Controlled Titanate-Catalyzed Condensation of Alkoxysilanes in Nonpolar Solvents". En ACS Symposium Series, 375–87. Washington, DC: American Chemical Society, 2003. http://dx.doi.org/10.1021/bk-2003-0838.ch031.

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Paul, Jared, Phillip Page, Philip Sauers, Katherine Ertel, Christina Pasternak, William Lin y Mariusz Kozik. "Transition-Metal-Substituted Heteropoly Anions in Nonpolar Solvents — Structures and Interaction with Carbon Dioxide". En Nanostructure Science and Technology, 205–15. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-47933-8_17.

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Jerome, R., G. Broze y Ph Teyssie. "Association of the Ion Pair End-Groups of Halato Telechelic Polymers in Nonpolar Solvents". En Microdomains in Polymer Solutions, 243–63. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2123-1_14.

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Kang, Tai Jong, Jongwan Yu y M. Berg. "Solvent Dynamics by Transient Holeburning: Nonpolar Versus Polar Solutes". En Springer Series in Chemical Physics, 414–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-84269-6_125.

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Bagchi, Biman y Ranjit Biswas. "Polar and Nonpolar Solvation Dynamics, Ion Diffusion, and Vibrational Relaxation: Role of Biphasic Solvent Response in Chemical Dynamics". En Advances in Chemical Physics, 207–433. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470141687.ch4.

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Durrington, P. N. "Lipid and lipoprotein disorders". En Oxford Textbook of Medicine, 1652–72. Oxford University Press, 2010. http://dx.doi.org/10.1093/med/9780199204854.003.1206_update_002.

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Lipids are a heterogeneous group of substances that are distinguished by their low solubility in water and their high solubility in nonpolar (organic) solvents. They are essential as energy stores and respiratory substrates, as structural components of cells, as vitamins, as hormones, for the protection of internal organs, for heat conservation, for digestion, and for lactation....
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Wu, Sizhu y Tarek M. Madkour. "Poly[1-(trimethylsilyl)-1-propyne]". En Polymer Data Handbook, 1085–87. Oxford University PressNew York, NY, 2009. http://dx.doi.org/10.1093/oso/9780195181012.003.0189.

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Abstract Major Applications Potential applications involve oxygen enrichment applicable to combustion furnaces, car engines, and respiration-aiding apparatuses. Also in the transport of oxygen dissolved in water applied to contact lenses and artificial lungs. In liquid mixture separation associated with ethanol concentration of fermented biomass. Furthermore, in polymer degradation related to resist materials for microlithography. Properties of Special Interest Glassy ductile polymer with high permeability and low selectivity. A white amorphous silicon containing acetylene stable to air and soluble in nonpolar solvents such as toluene, cyclohexane, and carbon tetrachloride. Thus, it allows for tough film formation by solution casting.
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Actas de conferencias sobre el tema "Nonpolar solvents"

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Park, N. S. y D. H. Waldeck. "Evidence for Multidimensional Stilbene Isomerization". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/up.1990.mc5.

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Different functional groups and their positions in the phenyl ring of stilbene and different solvents cause differences in the dipole moment, mass, volume and the surrounding environment of the solute during isomerization. These different properties of solute and solvent effect the isomerization rate in two ways, one is through the internal activation barrier and the other is the friction experienced by the solute while undergoing isomerization. Because the transition state has significant charge transfer character the dielectric coupling of the reaction coordinate with the solvent can modify the internal activation barrier [1]. In the case of alkyl substituted stilbenes in nonpolar solvents such effects are small. Such reasoning is why the system of alkyl-substituted stilbene in n-alkanes has been chosen for our studies addressing the dimensionality of photoisomerization in stilbenes.
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2

Yu, Jongwan, John T. Fourkas y Mark Berg. "Transient Hole Burning Studies of Electronic State Solvation: Phonon and Structural Contributions". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.thc17.

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Previously we showed that at room temperature the solvation of the nonpolar solute dimethyl-s-tetrazine (DMST) is subpicosecond, even in a variety of viscous solvents expected to show slow relaxation times.1 Measurements of solvation of DMST in glycerol have been extended from room temperature down to the low temperature glass. The solvation is shown to decompose into two major components: one describable in terms of phonon-modulated interactions, and one connected to the structural relaxation of the solvent.
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Kang, Tai Jong, Jongwan Yu y Mark Berg. "Solvent Dynamics by Transient Holeburning: Nonpolar vs Polar Solutes". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/up.1990.pdp1.

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Shank and coworkers have used ultrafast techniques to extend holeburning to the liquid phase, where they have observed the effects of rapid intramolecular relaxation [1]. Recently, there have been predictions that holeburning can also be used to study intermolecular interactions of solvents with the solute electronic states [2-4]. We present the first transient holeburning results attributable to intermolecular interactions. They show that large non-polar interactions can develop much more rapidly than the well-studied dipolar solvation interactions.
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4

Ishibashi, F., J. Kumasaka, T. Esaki y Y. Sugai. "Experimental Study on the Use of Nanoparticles to Improve the Efficiency of CO2 Geological Storage". En International Petroleum Technology Conference. IPTC, 2024. http://dx.doi.org/10.2523/iptc-23962-ea.

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Abstract Supercritical CO2 injected into the aquifer in CCS may migrate upward in the aquifer because its density is lower than the density of formation water. As a result, CO2 cannot be stored widely throughout the aquifer, which may reduce CO2 storage efficiency. The objective of this study is to increase the apparent density of supercritical CO2 by dispersing nanoparticles in itself and to improve CO2 storage efficiency by injecting CO2 widely in the aquifers. The n-hexane, which has a similar solubility parameter to supercritical CO2, was used as an alternative solvent to supercritical CO2 in this study. The nanoparticles such as SiO2, Al2O3, TiO2, and ZnO were added and stirred in n-hexane respectively, and their dispersibility was observed after stirring with a magnetic stirrer or ultrasonication for 30 minutes. The dispersibility of nanoparticles in n-hexane was qualitatively evaluated by irradiating the sample with green laser light after stirring and observing the scattered light. The effect of surfactants on improving the dispersibility of nanoparticles was also evaluated using nanoparticles modified with those surfactants. All the nanoparticles were precipitated after 30 minutes of stopping stirring with a magnetic stirrer. The dispersibility of those nanoparticles was improved by ultrasonication and the dispersion was maintained up to about 3 hours. Similar experiments were conducted using nanoparticles modified with surfactants. As a result, improved dispersibility of Al2O3 and ZnO modified with anionic surfactants was obviously observed and laser light scattering was clearly observed for about 2 hours after the stirring was stopped. Finally, it was demonstrated that the dispersion of Al2O3 nanoparticles modified with anionic surfactant was maintained even after 48 hours in n-hexane by ultrasonication. These results indicate that Al2O3 nanoparticles modified with anionic surfactant have high dispersibility in n-hexane, especially with ultrasonication. Anionic surfactants make the surface of nanoparticles hydrophobic, which enhances their dispersibility in nonpolar solvents such as supercritical CO2. Ultrasonication is effective for eliminating agglomeration among nanoparticles and improves their dispersibility in nonpolar solvents.
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5

Haley, L. V., T. L. Collier, T. A. Mattioli, D. L. Thibodeau y J. A. Koningstein. "Interferences in the Raman excitation profile for the intensity of normal modes of aggregated chlorophyll a". En International Laser Science Conference. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.thg2.

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If dry chlorophyll a is dissolved in dry nonpolar solvents, aggregation takes place and the degree of aggregation depends on the con centration of this large molecule. The pulsed laser-induced Raman spectrum of such solutions contains contributions from many species, including scattering from excited states in case the laser wavelength is in resonance with the Soret band. At resonance, the Raman intensities experience changes but the presence of close-lying short-lived excited states causes sharp interferences. They occur over a range of 50 cm-1 in the Soret band having a width of ~500 cm-1. Such patterns are fingerprints for such complicated molecules. Temporal aspects due to excited state Raman scattering also influence these profiles. Besides results on chlorophyll a in solution, we also show such interferences for electronic Raman scattering and discuss differences between the electronic and vibrational scattering processes.
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6

King, J. C., M. C. Asplund y C. B. Harris. "Vibrational Relaxation of a Charged Species in Nonpolar Solvent". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.pd.9.

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We have performed the first study of the vibrational relaxation of an ionic species, I2−, in a nonpolar solvent, CCl4. To determine the interaction of the charge with the solvent, results will be compared to a similar, but non-ionic species, I2, in the same solvent.
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Marković, Svetlana y Jelena Tošović. "CHLOROGENIC ACID – APPLICATION OF CONTEMPORARY DENSITY FUNCTIONALS TO A SINGLE MOLECULE". En 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac,, 2021. http://dx.doi.org/10.46793/iccbi21.081m.

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Although chlorogenic acid (5-O-caffeoylquinic acid, 5CQA) is a dietary phenol known for its pharmacological and nutritional properties, its structural features and mechanisms of oxidative action have not been completely elucidated. Clarification of the 5CQA structure was conducted by comparing the experimental and simulated IR, Raman, 1H-NMR, 13C-NMR, and UV spectra. For this purpose, a comprehensive conformational analysis of 5CQA was performed to reveal its most stable conformations in the gas-state and solution. Excellent agreement between all experimental and simulated spectra indicates correct arrangement of the atoms in the 5CQA molecule. In addition, the most stable conformation in solution coincides with that predicted with sophisticated NMR experiments. The quantum mechanics–based test for overall free-radical scavenging activity was applied for the investigation of antioxidative capacity of 5CQA relative to trolox (6-hydroxy-2,5,7,8- tetramethylchroman-2-carboxylic acid, Tx) as a reference compound. Hydrogen atom transfer (HAT), radical adduct formation (RAF), sequential proton loss electron transfer (SPLET), and single electron transfer – proton transfer (SET-PT) reactions of 5CQA and Tx with HO· and CH3OO· radicals were examined in benzene, pentyl ethanoate, and basic aqueous solutions. In non-polar solvents 5CQA reacts with HO· via HAT and RAF mechanisms, whereas HAT is the only reaction pathway with CH3OO·. At physiological conditions 5CQA exists in the form of monoanion and dianion. Both anionic forms undergo only HAT mechanism with CH3OO·. With HO·, the anions conform to the HAT, RAF, SPLET, and SET-PT mechanisms. Because all reactions of dianion are diffusion controlled, its contribution to scavenging HO· is comparable to that of more abundant monoanion. The calculated rate constant for overall reaction of 5CQA with HO· is in perfect agreement with the corresponding experimental value. The order of reactivity toward selected free radicals is the same in nonpolar and polar solutions: in comparison to Tx, 5CQA is more reactive toward HO·, but less reactive toward CH3OO·. Very good agreement between the experimental and calculated results confirms the ability of contemporary density functionals to quantify subtle physico-chemical interactions.
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Mialocq, J. C., P. Hébert, G. Baldacchino y T. Gustavsson. "Relaxation dynamics of a polar solvent cage around a nonpolar electronically excited solvent probe. A subpicosecond laser study". En Ultrafast reaction dynamics and solvent effects. AIP, 1994. http://dx.doi.org/10.1063/1.45390.

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Fourkas, John T., Andrea Benigno, Jangseok Ma, David Vanden Bout y Mark Berg. "Mechanical relaxation and solvation dynamics in nonpolar solutions". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.me.3.

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We have used transient hole burning measurements to make the first measurements of solvation dynamics in a completely nonpolar system: dimethyl-s-tetrazine (DMST) in n-butylbenzene.1,2 A new model for solvation based on the mechanical response of a viscoelastic solvent explains the main experimental features and predicts new features on the femtosecond timescale. Although the mechanical solvation mechanism is most prominent in nonpolar systems, it should play a role in all solvation3,4 and electronic dephasing5–8 processes.
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Nakakubo, T., K. Matsumoto y I. Shimoyama. "Patterning of micro-droplets in nonpolar solvent by electro-emulsification and electrophoresis". En 2013 IEEE 26th International Conference on Micro Electro Mechanical Systems (MEMS). IEEE, 2013. http://dx.doi.org/10.1109/memsys.2013.6474446.

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Informes sobre el tema "Nonpolar solvents"

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Lehotay, Steven J. y Aviv Amirav. Fast, practical, and effective approach for the analysis of hazardous chemicals in the food supply. United States Department of Agriculture, abril de 2007. http://dx.doi.org/10.32747/2007.7695587.bard.

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Background to the topic: For food safety and security reasons, hundreds of pesticides, veterinary drugs, and environmental pollutants should be monitored in the food supply, but current methods are too time-consuming, laborious, and expensive. As a result, only a tiny fraction of the food is tested for a limited number of contaminants. Original proposal objectives: Our main original goal was to develop fast, practical, and effective new approaches for the analysis of hazardous chemicals in the food supply. We proposed to extend the QuEChERS approach to more pesticides, veterinary drugs and pollutants, further develop GC-MS and LC-MS with SMB and combine QuEChERS with GC-SMB-MS and LC-SMB-EI-MS to provide the “ultimate” approach for the analysis of hazardous chemicals in food. Major conclusions, solutions and achievements: The original QuEChERS method was validated for more than 200 pesticide residues in a variety of food crops. For the few basic pesticides for which the method gave lower recoveries, an extensive solvent suitability study was conducted, and a buffering modification was made to improve results for difficult analytes. Furthermore, evaluation of the QuEChERS approach for fatty matrices, including olives and its oil, was performed. The QuEChERS concept was also extended to acrylamide analysis in foods. Other advanced techniques to improve speed, ease, and effectiveness of chemical residue analysis were also successfully developed and/or evaluated, which include: a simple and inexpensive solvent-in-silicone-tube extraction approach for highly sensitive detection of nonpolar pesticides in GC; ruggedness testing of low-pressure GC-MS for 3-fold faster separations; optimization and extensive evaluation of analyte protectants in GC-MS; and use of prototypical commercial automated direct sample introduction devices for GC-MS. GC-MS with SMB was further developed and combined with the Varian 1200 GCMS/ MS system, resulting in a new type of GC-MS with advanced capabilities. Careful attention was given to the subject of GC-MS sensitivity and its LOD for difficult to analyze samples such as thermally labile pesticides or those with weak or no molecular ions, and record low LOD were demonstrated and discussed. The new approach of electron ionization LC-MS with SMB was developed, its key components of sample vaporization nozzle and flythrough ion source were improved and was evaluated with a range of samples, including carbamate pesticides. A new method and software based on IAA were developed and tested on a range of pesticides in agricultural matrices. This IAA method and software in combination with GC-MS and SMB provide extremely high confidence in sample identification. A new type of comprehensive GCxGC (based on flow modulation) was uniquely combined with GC-MS with SMB, and we demonstrated improved pesticide separation and identification in complex agricultural matrices using this novel approach. An improved device for aroma sample collection and introduction (SnifProbe) was further developed and favorably compared with SPME for coffee aroma sampling. Implications, both scientific and agricultural: We succeeded in achieving significant improvements in the analysis of hazardous chemicals in the food supply, from easy sample preparation approaches, through sample analysis by advanced new types of GC-MS and LCMS techniques, all the way to improved data analysis by lowering LOD and providing greater confidence in chemical identification. As a result, the combination of the QuEChERS approach, new and superior instrumentation, and the novel monitoring methods that were developed will enable vastly reduced time and cost of analysis, increased analytical scope, and a higher monitoring rate. This provides better enforcement, an added impetus for farmers to use good agricultural practices, improved food safety and security, increased trade, and greater consumer confidence in the food supply.
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