Relevant bibliographies by topics / Cations

Academic literature on the topic 'Cations'

Author: Grafiati
Published: 4 June 2021
Last updated: 31 July 2024

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Cations.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Cations"

1

Lindner, Christoph, Raman Tandon, Boris Maryasin, Evgeny Larionov, and Hendrik Zipse. "Cation affinity numbers of Lewis bases." Beilstein Journal of Organic Chemistry 8 (August 31, 2012): 1406–42. http://dx.doi.org/10.3762/bjoc.8.163.

Full text
Abstract:
Using selected theoretical methods the affinity of a large range of Lewis bases towards model cations has been quantified. The range of model cations includes the methyl cation as the smallest carbon-centered electrophile, the benzhydryl and trityl cations as models for electrophilic substrates encountered in Lewis base-catalyzed synthetic procedures, and the acetyl cation as a substrate model for acyl-transfer reactions. Affinities towards these cationic electrophiles are complemented by data for Lewis-base addition to Michael acceptors as prototypical neutral electrophiles.
APA, Harvard, Vancouver, ISO, and other styles
2

Elicharova, Hana, and Hana Sychrova. "Fluconazole affects the alkali-metal-cation homeostasis and susceptibility to cationic toxic compounds of Candida glabrata." Microbiology 160, no. 8 (August 1, 2014): 1705–13. http://dx.doi.org/10.1099/mic.0.078600-0.

Full text
Abstract:
Candida glabrata is a salt-tolerant and fluconazole (FLC)-resistant yeast species. Here, we analyse the contribution of plasma-membrane alkali-metal-cation exporters, a cation/proton antiporter and a cation ATPase to cation homeostasis and the maintenance of membrane potential (ΔΨ). Using a series of single and double mutants lacking CNH1 and/or ENA1 genes we show that the inability to export potassium and toxic alkali-metal cations leads to a slight hyperpolarization of the plasma membrane of C. glabrata cells; this hyperpolarization drives more cations into the cells and affects cation homeostasis. Surprisingly, a much higher hyperpolarization of C. glabrata plasma membrane was produced by incubating cells with subinhibitory concentrations of FLC. FLC treatment resulted in a substantially increased sensitivity of cells to various cationic drugs and toxic cations that are driven into the cell by negative-inside plasma-membrane potential. The effect of the combination of FLC plus cationic drug treatment was enhanced by the malfunction of alkali-metal-cation transporters that contribute to the regulation of membrane potential and cation homeostasis. In summary, we show that the combination of subinhibitory concentrations of FLC and cationic drugs strongly affects the growth of C. glabrata cells.
APA, Harvard, Vancouver, ISO, and other styles
3

Morillo, E., J. L. Pérez-Rodríguez, and C. Maqueda. "Mechanisms of interaction between montmorillonite and 3-aminotriazole." Clay Minerals 26, no. 2 (June 1991): 269–79. http://dx.doi.org/10.1180/claymin.1991.026.2.10.

Full text
Abstract:
AbstractThe adsorption of aminotriazole, at its solution pH, with montmorillonite saturated with different cations has been studied. A pesticide-montmorillonite complex is formed through interlamellar cations which are not displaced. Aminotriazole is situated mostly as a polarized molecule around Mg2+ and Zn2+ cations, removing a great amount of water. In Na+- and Li+-montmorillonite, the pesticide remains as a non-polarized molecule, hydration water being retained in the interlamellar space; the pesticide is coordinated to interlamellar cations through water bridges. For all samples a proportion of cationic aminotriazole is also adsorbed, the amount being greater with increasing polarizing power of the interlamellar cation; consequently, in Fe3+-montmorillonite all the aminotriazole adsorbed is in the cationic form.
APA, Harvard, Vancouver, ISO, and other styles
4

Cozens, Frances L., V. M. Kanagasabapathy, Robert A. McClelland, and Steen Steenken. "Lifetimes and UV-visible absorption spectra of benzyl, phenethyl, and cumyl carbocations and corresponding vinyl cations. A laser flash photolysis study." Canadian Journal of Chemistry 77, no. 12 (December 5, 1999): 2069–82. http://dx.doi.org/10.1139/v99-210.

Full text
Abstract:
Benzyl (4-MeO, 4-Me, and 4-methoxy-1-naphthylmethyl), phenethyl (4-Me2N, 4-MeO, 3,4-(MeO)2, 4-Me, 3-Me, 4-F, 3-MeO, 2,6-Me2, parent, and 4-methoxy-1-naphthylethyl) and cumyl (4-Me2N, 4-MeO, 4-Me, parent) cations have been studied by laser flash photolysis (LFP) in 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoroisopropanol (HFIP). In most cases styrene or α-methylstyrene precursors were employed for the phenethyl and cumyl ions, the intermediate being obtained by solvent protonation of the excited state. Benzyl cations were generated by photoheterolysis of trimethylammonium and chloride precursors. While a 4-MeO substituent provides sufficient stabilization to permit observation of cations in TFE, cations with less stabilizing substituents usually require the less nucleophilic HFIP. Even in this solvent, the parent benzyl cation is too short-lived (lifetime <20 ns) to be observed. When generated in HFIP, phenethyl cations can be seen to react with unphotolyzed styrene, giving rise to dimer cations that are observed to grow in as the initial phenethyl cation decays. The dimer cations, in common with the oligomer cations seen in cationic styrene polymerization, have a λmax 15-20 nm higher than the monomer and react with both solvent and styrene several orders of magnitude more slowly. This stabilization relative to the phenethyl may reflect an interaction with the aryl group present at the gamma-carbon. Cations 4-MeOC6H4C+(R)-CH3 (R = Me, Et, i-Pr, t-Bu, cyclopropyl, C6H5, 4-MeOC6H4) were generated in TFE via the photoprotonation route. The alkyl series shows that steric effects are important in the decay reaction. The cation with R = cyclopropyl is a factor of 1.5 less reactive than the cation where R = phenyl. Several vinyl cations have also been generated by photoprotonation of phenylacetylenes. ArC+=CH2 has a reactivity very similar to that of its analog ArC+H-CH3, the vinyl cation being slightly (factors of 2-5) shorter-lived. For the various series of cations, including vinyl, substituents in the aryl ring have a consistent effect on the λmax, a shift to higher wavelength relative to hydrogen of 15 nm for 4-Me, 30 nm for 4-MeO, and 50 nm for 4-Me2N.Key words: photogenerated carbocations, carbocation lifetime, styrene, photoprotonation.
APA, Harvard, Vancouver, ISO, and other styles
5

Arnold, Donald R., and Xinyao Du. "The photochemical nucleophile–olefin combination, aromatic substitution (photo-NOCAS) reaction. Part 5: methanol–monoterpenes (α- and β-pinene, tricyclene, and nopol), 1,4-dicyanobenzene." Canadian Journal of Chemistry 72, no. 2 (February 1, 1994): 403–14. http://dx.doi.org/10.1139/v94-062.

Full text
Abstract:
The reactivity of the radical cations of α- and β-pinene (8 and 9), tricyclene (18), and nopol (23) has been studied. The radical ions were generated, in acetonitrile–methanol (3:1), by single electron transfer (set) to the singlet excited state of 1,4-di-cyanobenzene (1). Biphenyl (3) was used as a codonor. The cyclobutane rings of the initially formed radical cations of α- and β-pinene (8+• and 9+•) cleave to distonic radical cations that react as tertiary alkyl cations and allylic radicals. The results of ab initio molecular orbital calculations (STO-3G) are consistent with the observation that the positive charge is largely associated with the tertiary alkyl moiety while the spin density is largely distributed over the allylic radical. There was no evidence, experimental or theoretical, indicative of a bonding interaction between the cationic and allylic moieties of these distonic radical cations. The cyclobutane ring cleavage is irreversible. The radical cation of tricyclene (18) also gives 1:1:1 (nucleophile:cyclopropyl:aromatic) adducts. The regio- and stereochemistry of the adducts, and the nucleophile selectivity, are all indicative of nucleophile-assisted cleavage of the radical cation (18+•). The radical cation of nopol (23+•) also cleaves to the distonic radical cation. The cyclobutane ring cleavage must be rapid; intramolecular 1,5-endo cyclization of the hydroxyl group cannot compete.
APA, Harvard, Vancouver, ISO, and other styles
6

Venkatesan, P., V. Rajakannan, and S. Thamotharan. "Crystal structure of 3-amino-1-propylpyridinium bromide." Acta Crystallographica Section E Structure Reports Online 70, no. 12 (November 29, 2014): 580–83. http://dx.doi.org/10.1107/s1600536814025665.

Full text
Abstract:
The title molecular salt, C8H13N2+·Br−, crystallizes with two independent 3-aminopyridinium cations and two bromide anions in the asymmetric unit (Z′ = 2). In the pyridine ring, the N atom is alkylated by a propyl group. The dihedral angle between the mean planes of the pyridinium ring and the propyl group is 84.84 (2)° in cationA, whereas the corresponding angle is 89.23 (2)° in cationB. In the crystal, the anions and cations are linkedviaN—H...Br and C—H...Br hydrogen bonds, forming chains propagating along [100].
APA, Harvard, Vancouver, ISO, and other styles
7

Mamedova, G. A. "THE ION-EXCHANGE PROPERTIES OF NATURAL ZEOLITE MORDENITE." Fine Chemical Technologies 11, no. 1 (February 28, 2016): 29–33. http://dx.doi.org/10.32362/2410-6593-2016-11-1-29-33.

Full text
Abstract:
The cation exchange properties of mordenite (a Nakhchivan natural zeolite) were studied. Ion exchange of the original cations - sodium, potassium and calcium - by magnesium, strontium, cadmium, zinc and nickel cations was carried out. It was found that in the case of Zn cations cation exchange occurs readily at a high speed and the maximum value of the degree of exchange. A low value of the degree of cation exchange is observed for Mg. This is due to the large hydration shell of magnesium, which adversely affects the cation exchange. High values of the exchange rate of Na+ cations have already been explained at the first exchange of low content of sodium cations and their location mostly in exchange for positions available. The lesser ability to exchange K+, Na+ cations than contained in the natural zeolite is due to several reasons. With an increasing number of degrees of ionic exchange value exchangeable cations K+ vary to a greater degree than the degree of exchange of the cations Na+. Firstly, the content and size of the K+ cation are greater than those of the Na+ cations. Furthermore, a part of the K+ cations is in exchange for hard cancrinites cells. It has been found that the degree of cation exchange of K+ (αK), contained in the original zeolite, with Mg2+, Ni2+, Sr2+, Zn2+, Cd2+ cations is considerably lower than the values of the degree of cation exchange of Na+ (αNa) at the same cations.
APA, Harvard, Vancouver, ISO, and other styles
8

Philipp, Jule, and Ralf Ludwig. "Clusters of Hydroxyl-Functionalized Cations Stabilized by Cooperative Hydrogen Bonds: The Role of Polarizability and Alkyl Chain Length." Molecules 25, no. 21 (October 27, 2020): 4972. http://dx.doi.org/10.3390/molecules25214972.

Full text
Abstract:
We explore quantum chemical calculations for studying clusters of hydroxyl-functionalized cations kinetically stabilized by hydrogen bonding despite strongly repulsive electrostatic forces. In a comprehensive study, we calculate clusters of ammonium, piperidinium, pyrrolidinium, imidazolium, pyridinium, and imidazolium cations, which are prominent constituents of ionic liquids. All cations are decorated with hydroxy-alkyl chains allowing H-bond formation between ions of like charge. The cluster topologies comprise linear and cyclic clusters up to the size of hexamers. The ring structures exhibit cooperative hydrogen bonds opposing the repulsive Coulomb forces and leading to kinetic stability of the clusters. We discuss the importance of hydrogen bonding and dispersion forces for the stability of the differently sized clusters. We find the largest clusters when hydrogen bonding is maximized in cyclic topologies and dispersion interaction is properly taken into account. The kinetic stability of the clusters with short-chained cations is studied for the different types of cations ranging from hard to polarizable or exhibiting additional functional groups such as the acidic C(2)-H position in the imidazolium-based cation. Increasing the alkyl chain length, the cation effect diminishes and the kinetic stability is exclusively governed by the alkyl chain tether increasing the distance between the positively charged rings of the cations. With adding the counterion tetrafluoroborate (BF4−) to the cationic clusters, the binding energies immediately switch from strongly positive to strongly negative. In the neutral clusters, the OH functional groups of the cations can interact either with other cations or with the anions. The hexamer cluster with the cyclic H-bond motive and “released” anions is almost as stable as the hexamer built by H-bonded ion pairs exclusively, which is in accord with recent IR spectra of similar ionic liquids detecting both types of hydrogen bonding. For the cationic and neutral clusters, we discuss geometric and spectroscopic properties as sensitive probes of opposite- and like-charge interaction. Finally, we show that NMR proton chemical shifts and deuteron quadrupole coupling constants can be related to each other, allowing to predict properties which are not easily accessible by experiment.
APA, Harvard, Vancouver, ISO, and other styles
9

Gärtner, Stefanie, Christof Suchentrunk, and Nikolaus Korber. "Coordination preferences of the alkali cations sodium and caesium in the mixed-cationic Zintl ammoniate Cs3.2Na0.8Ge9·5.3NH3." Acta Crystallographica Section C Structural Chemistry 70, no. 11 (October 11, 2014): 1036–39. http://dx.doi.org/10.1107/s2053229614021998.

Full text
Abstract:
The involvement of two different alkali cations in the nonagermanide ammoniate Cs3.2Na0.8Ge9·5.3NH3[tricaesium sodium nonagermanide–ammonia (1/5.3)] provides insights into the coordination behaviour of ammonia towards sodium and caesium cations within one compound and represents the first mixed-cationic solvate structure of nonagermanide tetraanions. The compound crystallizes in the monoclinic space groupP21/mand, with the presence of pseudomerohedral twinning, mixed-cation sites and disordering of the nonagermanide cage anions, features a combination of crystallographic challenges which could all be resolved during the refinement.
APA, Harvard, Vancouver, ISO, and other styles
10

Bolanle-Ojo, Tope O., Abiodun D. Joshua, Opeyemi A. Agbo-Adediran, Ademola S. Ogundana, Kayode A. Aiyeyika, Adebisi P. Ojo, and Olubunmi O. Ayodele. "Exchange Characteristics of Lead, Zinc, and Cadmium in Selected Tropical Soils." International Journal of Agronomy 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/428569.

Full text
Abstract:
Conducting binary-exchange experiments is a common way to identify cationic preferences of exchangeable phases in soil. Cation exchange reactions and thermodynamic studies of Pb2+/Ca2+, Cd2+/Ca2+, and Zn2+/Ca2+were carried out on three surface (0–30 cm) soil samples from Adamawa and Niger States in Nigeria using the batch method. The physicochemical properties studies of the soils showed that the soils have neutral pH values, low organic matter contents, low exchangeable bases, and low effective cation exchange capacity (mean: 3.27 cmolc kg−1) but relatively high base saturations (≫50%) with an average of 75.9%. The amount of cations sorbed in all cases did not exceed the soils cation exchange capacity (CEC) values, except for Pb sorption in the entisol-AD2 and alfisol-AD3, where the CEC were exceeded at high Pb loading. Calculated selectivity coefficients were greater than unity across a wide range of exchanger phase composition, indicating a preference for these cations over Ca2+. TheKeqvalues obtained in this work were all positive, indicating that the exchange reactions were favoured and equally feasible. These values indicated that the Ca/soil systems were readily converted to the cation/soil system. The thermodynamic parameters calculated for the exchange of these cations were generally low, but values suggest spontaneous reactions.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Cations"

1

DAHHANI, FADIL. "Reactions des cations et cations radicaux en phase gazeuse." Paris 6, 1996. http://www.theses.fr/1996PA066107.

Full text
Abstract:
L'objectif de cette these est l'etude des reactions unimoleculaires et bimoleculaires en phase gazeuse. Elle comporte quatre parties: la premiere presente un expose sur les generalites de la spectrometrie de masse et un apercu sur quelques mecanismes d'isomerisation connus en phase gazeuse et en phase condensee. Les processus d'isomerisation entre cations radicaux solvates et ions -distoniques sont etudies dans une deuxieme partie apres avoir rappele les principales caracteristiques des ions distoniques. Il a ete notamment montre que cette isomerisation a faible energie critique evolue toujours dans le sens exothermique de la reaction: l'isomerisation de ch#3oh#+#. En ion -distonique #. Ch#2oh#2#+ plus stable peut etre catalysee par des neutres appropries, h#2o notamment, alors que la reaction inverse n'est pas observee. L'etude du caractere ambivalent de ch#3och#2#+ a ete traitee dans une troisieme partie. L'analyse des resultats des reactions du cation ch#3och#2#+ avec une serie d'alcools, cetones, aldehydes, diols a montre que ce cation peut avoir le caractere electrophile classique et d'autre part peut etre transporteur du methyle. Enfin dans une quatrieme partie sont rassemblees les differentes techniques utilisees au cours de cette these pour decrire les reactions unimoleculaires et bimoleculaires en phase gazeuse
APA, Harvard, Vancouver, ISO, and other styles
2

Kildahl-Andersen, Geir. "Polyenyl cations and radical cations – synthesis, spectroscopic properties and reactions." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemistry, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1790.

Full text
Abstract:

In the present work, polyene precursors for the formation of charged polyenyl species were synthesised. Their conversion to charge delocalised radical cations and diamagnetic mono- and dications was carried out by treatment with Brønsted and Lewis acids. Reaction conditions were optimised to achieve sufficient stability of the charged polyenes for characterisation by modern spectroscopic methods; in particular nearinfrared absorption spectroscopy (NIR), two-dimensional nuclear magnetic resonance (2D NMR), electron paramagnetic resonance (EPR) and dynamic light scattering.

The full assignment of 13C NMR chemical shifts of mono- and dications was used as basis for charge distribution estimates in charge delocalised polyenes. Coulombic repulsions are dominant features in dicationic systems, whereas monocations show a more even distribution of charge throughout the polyene system. The size limit of charge delocalisation regions, suggested by current theories, has been investigated using an empirical approach. Treatment of the cationic polyenes with nucleophiles gave conversion to neutral compounds, which were characterised by mass spectrometry (MS) and ultraviolet/ visible absorption spectroscopy (UV/Vis), in addition to NMR. In most cases, theidentified neutral compounds supported the structural characterisation of their charged precursors.

The work is of relevance to the classical blue colour reactions of polyenes developed in the early 20th century. The chemistry behind these reactions has previously not been elucidated. Only during the last 15-20 years has the instrumental methods necessary for the study of this chemistry been available.

In current studies on the colouration mechanism of the carotenoproteins present in external tissues of some marine organisms, a polarisation of the polyene chain appear to be of importance. Moreover, radical cations of polyenes are unstable intermediates in Nature, where they are shown to be of importance in photosynthetic processes in green plants and bacteria.

The delocalised polyenylic cations studied here, representing a new direction of structural studies in the carotenoid/retinoid field, are of interest in a wider context for carbocation structure and stability in basic organic chemistry and the various applied aspects outlined above.

APA, Harvard, Vancouver, ISO, and other styles
3

Müller, Wolfram. "Extraction liquide-solide de cations métalliques par des cations amphiphiles." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20173/document.

Full text
Abstract:
Dans le domaine de la séparation sélective pour le traitement et la valorisation des combustibles nucléaires usés, l'extraction liquide-liquide est largement utilisée au niveau industriel. Cependant dans le cadre des technologies nucléaires du futur, des procédés alternatifs de séparation sont recherchés. Notamment la précipitation sélective d'actinides par des tensioactifs cationiques en milieu aqueux (l'extraction liquide-solide étudié par Heckmann et al dans les années 80) apparaît comme une approche intéressante. Le principal avantage de cette technique, comparée à l'extraction liquide-liquide, est lié à la diminution du nombre d'étapes dans le processus comme le lavage du solvant ou la désextraction des métaux. De plus, c'est une technique sans solvant organique ce qui réduit considérablement la quantité de déchets contaminés. Pour ces travaux de thèse, nous avons utilisé des méthodes physico-chimiques pour mieux comprendre l'interaction spécifique entre le cation métallique et le tensioactif cationique. Nous avons tout d'abord analysé l'effet spécifique des contre-ions anioniques (Cl-, NO3-, C2O42-) provenant des acides utilisés; puis nous avons étudié finement l'introduction de cations alcalins monovalents et quelques cations multivalents sélectionnés (Cu2+, Zn2+, UO22+, Fe3+, Nd3+, Eu3+, Th4+) sur l'auto-assemblage et les propriétés structurels du tensioactif en variant les conditions thermodynamiques. Nous en avons conclu que l'adsorption d'un complexe anionique stable du métal, à l'interface des agrégats micellaires, influence fortement les paramètres d'agrégation du tensioactif et détermine ainsi les limites d'utilisation de cette technique de séparation
In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX …) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl-, NO3-, C2O42-) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu2+, Zn2+, UO22+, Fe3+, Nd3+, Eu3+, Th4+) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration
APA, Harvard, Vancouver, ISO, and other styles
4

CRESPI, STEFANO. "New Intermediates from Photogenerated Phenyl Cations." Doctoral thesis, Università degli studi di Pavia, 2017. http://hdl.handle.net/11571/1203367.

Full text
Abstract:
La tesi presenta uno studio sulla fotoreattività di composti aromatici volta ad ampliare la classe di substrati in grado di fotogenerare alfa,n-dideidrotolueni a partire da aril cationi nel loro stato di tripletto. Viene riportato inoltre lo studio fotochimico di arilazo mesilati come nuovi prescursori di aril cationi e radicali. In aggiunta viene presentato un approccio fotocatalitico per la generazione di intermedi reattivi svoltosi presso l’Università di Ratisbona. Il lavoro è corredato dallo studio computazionale e meccanicistico sulle reazioni fotochimiche studiate sperimentalmente.
This thesis is devoted to the study of the aromatic compounds photoreactivity and in particular to widen the number of alfa,n didehydrotoluenes precursors from photogenerated triplet aryl cations. The photochemical investigation on arylazo mesylates photoreactivity as novel aryl radicals and cations generators is also presented. Moreover, all reactions experimentally studied are analysed on the basis of computational chemistry.
APA, Harvard, Vancouver, ISO, and other styles
5

Robin, Dorothée. "Réactions unimoléculaires des cations ou cations radicaux hétérocycliques et oxygénés en phase gazeuse." Paris 11, 1986. http://www.theses.fr/1986PA112306.

Full text
Abstract:
Ce travail porte sur les mécanismes d’isomérisation et de fragmentation des cations et cations radicaux d’hétérocycles saturés et insaturés en phase gazeuse. Un bref exposé des généralités sur la spectrométrie de masse et sur les mécanismes d’isomérisation des carbocations précède la première partie de ce travail où sont comparés les comportements des ions [M-H]+ provenant des cycles et d’hétérocycles aromatiques. Le comportement des ions alkylfurannes et alkylbenzofurannes protonés est étudiés dans une deuxième partie ainsi que celui d’ions adduits isomères ; Cette étude rend compte de l’existence de processus compétitifs d’isomérisation par transfert 1-2 de méthyle et par des réactions d’agrandissement et de rétrécissement de cycle. Dans une troisième partie, les cations radicaux phtalanne et dihydrobenzofuranne ainsi que leurs homologues supérieurs sont étudiés ; Il a été montré notamment que le cation radical isochromanne se fragmente suivant une réaction de DIELS ALDER et que le cation radical phényloxétanne se réarrange à faible énergie interne en cation radical isochromanne. Les mécanismes de protonation et d’isomérisation du phtalanne, du dihydrobenzofuranne et de leurs homologues supérieurs sont traités dans une quatrième partie. Si les formes protonées du chromanne s’isomérisent entre elles, celles de l’isochromanne ont un comportement autre. Il ressort de l’étude de nombreux isomères que l’allyl phényl éther protoné se réarrange en chromanne protoné puis en ortho propényl phénol protoné.
APA, Harvard, Vancouver, ISO, and other styles
6

Nougué, Raphaël. "Silylènes stabilisés par des phosphines : précurseurs de nouveaux cations silyliumylidènes et hétérocycles insaturés." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30021/document.

Full text
Abstract:
Ce travail de thèse est axé sur la réactivité de silylènes stabilisés par un ligand phosphine et notamment leur usage en tant que précurseurs de cations silyliumylidènes (R-Si:+), qui sont des espèces cationiques du silicium avec seulement un substituent et 4 électrons de valences. La stabilisation des silyliumylidènes, espèces hautement réactives, sera envisagée via la coordination des deux bases de Lewis au niveau des deux orbitales vacantes du centre silicié cationique. Le premier chapitre constitue un état de l'art des études portant sur la stabilisation et la réactivité des silylènes. Une emphase particulière a été apportée à la description de leurs propriétés électroniques qui sont responsables de la balance stabilité-réactivité de ces espèces. Le deuxième chapitre présente la réactivité des complexes de silylènes stabilisés par un ligand phosphine dans l'activation réversible des liaisons- E-H (E = R3Si, R2P) via des additions oxydantes/éliminations réductrices. Ce type de réaction est relativement rare pour les complexes non-métalliques mais fréquent avec les complexes de métaux de transition. Le dernier chapitre traite de la synthèse et de la caractérisation d'espèces divalentes cationiques Si(II), les cations silyliumylidènes stabilisés par coordination de deux de ligands L différents comme les phosphines, les sulfures, les pyridines et les carbènes N-hétérocycliques NHC. Parmi les espèces préparées, le cation silyliumylidène stabilisé par une phosphine, de façon intramoléculaire, et le diméthylsulfure, base de Lewis labile, se distingue par une très grande réactivité vis-à-vis de réactifs variées (oléfines, alcynes, silanes,...) conduisant à des cations silylium stabilisés, intramoléculairement, par un ligand phosphine. Ces derniers, restant très réactifs, sont capables de réagir avec un autre substrat. Ces résultats montrent clairement que les silyliumylidènes sont capables d'activer successivement deux molécules différentes, ce qui devrait permettre d'envisager leur utilisation comme des catalyseurs similaires aux complexes de métaux de transition
This thesis focuses on the reactivity of phosphine stabilized silylenes, and particularly their use as precursors of low-coordinate four-valence-electrons silyliumylidene ions (R-Si:+). The stabilization of those highly reactive species will be considered via the coordination of two Lewis bases at the cationic silicon center featuring formally two empty orbitals. In the first chapter an overview concerning the stabilization and reactivity of silylenes is presented. Particular emphasis has been placed on the description of their electronic properties which are responsible for the stability-reactivity balance of these derivatives. The second chapter concerns the use of phosphine-stabilized silylene complexes for the reversible activation of E-H bonds (E = R3Si, R2P) via oxidative addition/reductive elimination processes, which are classical in organometallic chemistry, but rarely observed for main group element species. The last chapter deals with the synthesis and characterization of silyliumylidene ions (R-Si:+), and particularly we have considered their stabilization using a set of two different L ligands such as phosphines, sulfides, pyridines and N-heterocyclic carbenes NHC. Of special interest, the phosphine/dimethylsulfide-stabilized silyliumylidene cation, thanks to the labile sulfide ligand, presents a very high reactivity with various reagents (olefins, alkynes, silanes,...), leading to the formation of the corresponding silylium cations, intramolecularly-stabilized by a phosphine ligand. These latter, remaining very reactive, are able to activate a second type of substrate. These results clearly show that the sililymilydenes are capable of activating successively two different molecules, which should make it possible to envisage their use as catalysts similarly to transition metal complexes
APA, Harvard, Vancouver, ISO, and other styles
7

Teasdale, Andrew. "Synthetic ionophores for cations." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5617/.

Full text
Abstract:
A series of 14-crown-4 derivatives bearing amide substituents have been prepared in order to develop ionophores selective for lithium. Complexation with lithium ions was monitored using ( 13)C and IR spectroscopy and liquid membrane electrodes prepared and evaluated using a fixed interference method. The highest selectivities with respect to sodium ions were obtained for di-n-butylamide-oNPOE and a di-n-benzylamide-oNPOE derivatives; log( POT)(_ Li,Na) = -2.92 and -2.93 respectively. A series of amide and amide-ester N-functionalised coronands based upon [12]-N202 , [15]-N203 and [18]-N204 parent macrocycles has been prepared. Complexation of certain alkali and alkaline-earth cations was monitored by ( 13)C NMR and IR specteoscopy, enthalpies of complexation measured in methanolic solution using micro-calorimetry and stability constants measured in aqueous media by potentiometric methods. Strong complexation of Ca2+ in aqueous media was observed with good selectivity over Na+ and K+. Lower free energies of binding for Ha cations were displayed by the tertiary amide derivative (of [12]N(_2)O(_2)), than by its secondary analogue, despite displaying higher enthalpies of complexation. Thus the lower free energies result from significantly lower entropies of complexation. Two sets of oxa-amide and oxa-ester tripodal ligands have been prepared and solvent membranes fabricated. The effects of the nature of the plasticiser, bis (butylpentyl)adipate (BBPA) verses o -nitrophenyl octyl ether (oNPOE), the ligand structure and the ionic strength of the analyte solution on the electrode response to la and Ila cations were studied. The performance of the oxa-amides was superior to that of the oxa-esters particularly at higher ionic strengths, however super-Nernstian responses were observed with the more charge-dense ions in the presence of chloride and/or with the less polar plasticiser BBPA. Measurements of intracellular sodium concentration could be effected with a sensor based upon bis (N,N',N"-tributyl)-4,4',4"-propylidintris(3-oxabutanamide) and oNPOE for which -log KPOT = 2.64 and -log KPOT =3.0, whilst bis (N,N',N"-tributyl)Na,K Na,Mg-2,2',2"-phenylmethylidintris(3-oxabutamide) and oNPOE functioned as a calcium sensor, displaying excellent selectivity over Mg. -log KPOT= 4.3.Ca,MgAdditionally a triamide based upon a cyclohexane triol skeleton was prepared, a membrane fabricated and its performance assessed as a sodium sensor.
APA, Harvard, Vancouver, ISO, and other styles
8

Robin, Dorothée. "Réactions unimoléculaires des cations ou cations radicaux hétérocycliques et oxygènes en phase gazeuse." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37600792s.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Fauvelle, Florence. "Décontamination des cations toxiques : la voie des cyclodextrines." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE19003.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Depauw, Alexis. "Synthèse et étude photophysique de sondes fluorescentes pour la détection de cations alcalins en milieux aqueux." Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0040/document.

Full text
Abstract:
L’objet de cette thèse a été la réalisation de sondes moléculaires fluorescentes pour de la détection de césium et de potassium en milieu aqueux. Deux problématiques ont été abordées : la détection de traces de césium en vue d’applications environnementales, et la mesure de variations de potassium en milieu biologique en vue d’applications biologiques. La première partie de cette thèse concerne la détection du césium. Dans un premier temps, différentes entités complexantes du césium ont été étudiées dans le but de mesurer des concentrations de césium comprises entre 1.10-3 et 5 ppm. Certaines de ces sondes ont ensuite été utilisées au sein d’un système de mesures basé sur un circuit micro-fluidique destiné à mesurer le césium de façon continue. La seconde partie de cette thèse s’intéresse à la détection du potassium. Dont le but a été de mettre au point des sondes pour mesurer le potassium extracellulaire par imagerie de fluorescence. Une cage complexante sélective du potassium a tout d’abord été identifiée. Différentes stratégies ont ensuite été développées pour remplacer la coumarine par un fluorophore excitable à de plus hautes longueurs d’ondes. Parmi les sondes étudiées, le Calix-COU-Alcyne-Sulf a permis d’effectuer des mesures in vitro préliminaires qui ont montré que ce type de sondes ne perturbe pas l’activité neuronale et permet de détecter le potassium dans la gamme de concentration visée
The aim of this PhD was to study fluorescent molecular sensors in order to detect cesium and potassium in aqueous media. Two different issues have been addressed: the detection of cesium traces for environmental applications, and the measure of potassium fluctuations for biological applications. The first part concerns the detection of cesium. Several complexing units were first studied, to measure cesium concentration between 1.10-3 and 5 ppm. Some of the molecules made were then used in a measuring system based on a micro-fluidic chip to measure cesium in a continuous way. The second part concerns the detection of potassium. The aim was to design sensors to measure extracellular potassium fluctuations by fluorescence imaging. A selective complexing unit was first found. Several strategies were then explored to replace a coumarin by a fluorophore excitable at higher wavelengths. Among the molecules made, the Calix-COU-Alcyne-Sulf enabled preliminary in vitro measurements and showed that this type of molecules does not affect the neuronal activity and enables to measure potassium in the range of concentration targeted
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Cations"

1

Baes, Charles F. The hydrolysis of cations. Malabar, Fla: R.E. Krieger, 1986.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
2

A, Pasternak Charles, ed. Monovalent cations in biological systems. Boca Raton, Fla: CRC Press, 1990.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

Kannicht, Christoph, ed. Post-translational Modifi cations of Proteins. Totowa, NJ: Humana Press, 2008. http://dx.doi.org/10.1007/978-1-60327-084-7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Forbes, Malcolm D. E., ed. Carbon-Centered Free Radicals and Radical Cations. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2009. http://dx.doi.org/10.1002/9780470584118.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Heyes, David William. Synthesis and properties of substituted heteroaromatic cations. Manchester: University of Manchester, 1993.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

Forbes, Malcolm D. E., 1960-, ed. Carbon-centered free radicals and radical cations. Hoboken, N.J: Wiely, 2010.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

Yang, Zheren Jim. Ionic Hydrogenation of Pyridinium and Azetidinium Cations. [New York, N.Y.?]: [publisher not identified], 2017.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

Nechaeva, L. S. Strukturnyĭ analiz kationoobmennikov: Monografii︠a︡. Voronezh: Izdatelʹsko-poligraficheskiĭ t︠s︡entr "Nauchnai︠a︡ kniga", 2012.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

Heyes, David William. Structure-reactivity relationships in reductions of heteroaromatic cations. Manchester: University of Manchester, 1995.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
10

Topchiev, D. A. Kationnye poliėlektrolity: Poluchenie, svoĭstva i primenenie. Moskva: Akademkniga, 2004.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Cations"

1

Peter, L. B. "Polysulfur Cations." In Inorganic Reactions and Methods, 26–27. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145197.ch33.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Chivers, T. "Polyselenium Cations." In Inorganic Reactions and Methods, 35–36. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145197.ch43.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Chivers, T. "Polytellurjum Cations." In Inorganic Reactions and Methods, 38–39. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145197.ch48.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Chivers, T. "Heteropolyatomic Cations." In Inorganic Reactions and Methods, 42–43. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145197.ch53.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Cutforth, B. D., R. J. Gillespie, A. G. Macdiarmid, and N. D. Miro. "Polymercury Cations." In Inorganic Syntheses, 22–27. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470132500.ch6.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Johnson, D. W. "Base Cations." In Ecological Studies, 233–340. New York, NY: Springer New York, 1992. http://dx.doi.org/10.1007/978-1-4612-2806-6_8.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Thomas, Grant W. "Exchangeable Cations." In Agronomy Monographs, 159–65. Madison, WI, USA: American Society of Agronomy, Soil Science Society of America, 2015. http://dx.doi.org/10.2134/agronmonogr9.2.2ed.c9.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Hopkinson, Alan C., and K. W. Michael Siu. "Peptide Radical Cations." In Principles of Mass Spectrometry Applied to Biomolecules, 301–35. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/047005042x.ch9.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Calera, José Antonio, and Hubertus Haas. "Cations (Zn, Fe)." In Aspergillus fumigatus and Aspergillosis, 107–29. Washington, DC, USA: ASM Press, 2014. http://dx.doi.org/10.1128/9781555815523.ch9.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Glass, Richard S. "Sulfur Radical Cations." In Topics in Current Chemistry, 1–87. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-48986-x_1.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Cations"

1

Laivins, G. V., and A. M. Scallan. "The Exchange and Removal of the Metal Cations in Pulps." In The Fundamentals of Papermaking Materials, edited by C. F. Baker. Fundamental Research Committee (FRC), Manchester, 1997. http://dx.doi.org/10.15376/frc.1997.2.837.

Full text
Abstract:
Metal cations modify the optical and mechanical properties of pulps and in pulp mills can have adverse effects on such parameters as corrosion rate and recovery furnace temperature. With today’s emphasis on recycling effluents and on tighter control of all operations, there is a need for quantitative theory predicting the uptake of cations by pulps and the buildup of cations in process liquors. A variation of the Donnan Equilibrium Theory was recently developed to describe the partitioning of cations between the fibres and the liquor in a pulp suspension [1]. In this report we extend use of the theory to examine the ion-exchange of pulps from saturation with one cation to saturation with another. Theoretical predictions are closely duplicated by experiments using sodium, magnesium and lanthanum as model cations of different valencies. Pulps readily exchange cations even with very dilute solutions, preferentially taking up and most tenaciously holding the higher valency cations. Consequently, the replacement of high valency cations by monovalent cations requires higher concentrations of the replacement ion than for the reverse exchange. The differing tenacities by which cations are held are also shown during acid washing of pulps. Upon progressively lowering the pH of a suspension of pulp in mixed ionic form, monovalent, divalent and trivalent cations are successively released and replaced by hydrogen ions. The implication of these results for the “acid washing” of pulps is discussed.
APA, Harvard, Vancouver, ISO, and other styles
2

Rousseau, David, and Mathieu Salaün. "Impact Of Cation Exchange On Polymer In-Situ Viscosity: An Experimental Investigation For A Low-Salinity Polymer Flooding Case." In International Petroleum Technology Conference. IPTC, 2023. http://dx.doi.org/10.2523/iptc-22907-ms.

Full text
Abstract:
Abstract Cation exchange occurs when water with a different salinity as the connate brine is injected in a reservoir. During polymer flooding operations, the potential release of divalent cations by the rock can have a detrimental impact on the in-situ viscosity in the polymer bank. The objective of this work was to assess for the risk related to cations exchange in an Argentinian oilfield and to provide guidelines for the injection water design. Reservoir rock samples were first submitted to mineralogical analysis involving scanning-electron microscopy (SEM), X-Ray Diffraction (XRD) and determination of their Cation Exchange Capacities (CEC). Coreflood tests were then performed where the effluents were analyzed for their cations composition. In these experiments, two main scenarios for the composition of the low-salinity injection water (with or without softening) were investigated and the transport properties of the polymer were determined. As a more exploratory approach, polymer was also injected in a 12-meter-long slim tube filled with crushed reservoir rock, to assess if it could be exposed to released cations. The results showed that all reservoir rocks investigated had high CEC, which was consistent with their high clay contents, and that significant cations exchanges took place during low salinity water injection, although no formation damage occurred, showing the stability of the clays. During injection of the softened water, evidences of significant divalent (and monovalent) cations release from the rock were found. During injection of the unsoftened water, a marked and long-term adsorption of the injected calcium cations was observed, corresponding to a depletion in calcium of the injected water. This suggests that, quite counter-intuitively, using unsoftened water as polymer make up water could be interesting in view of economics because the cations exchanges could entail an increase of the in-situ viscosity. The coreflood test results also showed that the presence of polymer in the injected water had no impact on the cations exchanges mechanisms. The partial results from the slim tube injection test suggested, however, that the retardation of the polymer bank caused by polymer adsorption was sufficient to avoid for its viscosity to be affected by the changes in cations distribution. This study illustrates the importance of cation exchange mechanisms and their potential impact for polymer flooding. It also shows that these effects can be investigated in a representative manner at the lab and that practical guidelines for the composition of the polymer injection water can be deduced from the experiments, provided a risk for in-situ viscosity reduction is identified.
APA, Harvard, Vancouver, ISO, and other styles
3

Al Ezzi, Amged, and Hongbin Ma. "Equilibrium Adsorption Isotherm Mechanism of Water Vapor on Zeolites 3A, 4A, X, and Y." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-72601.

Full text
Abstract:
Many researchers have analyzed the equilibrium adsorption isotherm mechanism of water vapor molecules on 4A, 3A, Y and X zeolites for decades. The demand for moisture removal continues to increase along with the increasing stringency of requirements for product quality control and production energy efficiency. Due to the negative charge of the zeolite framework, exchangeable compensation cations such as Na+, Li+, K+, Ba2+, Mg2+, and Ca2+ might be added. These cations are located at different sites within the framework and with different concentrations. Each cation shows a strong affinity to bond with water molecules. Adsorption sites must show a characteristic energy signature corresponding to the adsorbed amount. The values of enthalpies and entropies at each site are different since the bonding strength between the moisture molecules and cations of the site is also different. These exchangeable cations have a very important contribution in determining the zeolites adsorptive properties and selectivity. This investigation of the water vapor adsorption mechanism reveals that size, location, and type of exchangeable compensation cations have a concrete relationship to the adsorption process and zeolite cage capacity.
APA, Harvard, Vancouver, ISO, and other styles
4

Ge, Xiaojing, Ghith Biheri, Abdulmohsin Imqam, Baojun Bai, and Yuwei Zhang. "Experimental Study: Investigating the Anions and Cations’ Effects on the Elasticity of the Anionic and Cationic High Viscosity Friction Reducers." In SPE Western Regional Meeting. SPE, 2023. http://dx.doi.org/10.2118/213048-ms.

Full text
Abstract:
Abstract High viscosity friction reducers (HVFRs) are widely used as friction-reducing agents and proppant carriers during hydraulic fracturing. The reuse of produced water has gained popularity due to environmental and economic benefits. Currently, the field’s most commonly used friction reducers are anionic and cationic HVFRs. Anionic HVFRs are typically pumped with freshwater, while cationic HVFRs are used with high Total Dissolved Solids (TDS) produced water. Cationic friction reducers are believed to have better TDS tolerance, friction reduction performance, and proppant transport capabilities compared to anionic friction reducers under high TDS conditions due to their superior viscoelastic properties. In addition, the impact of different anions and cations on the viscosity of HVFRs has been thoroughly studied, and viscosity reduction mechanisms include charge shielding, increasing the degree of hydrolysis, and forming coordination complexes. However, anions and cations’ effects on the elasticity of HVFRs still remain to be investigated. Besides, most previous experimental studies either do not specify experimental procedures or control the experimental variables well. Therefore, the ultimate objective of this experimental study is to analyze various cations and anions’ effects on the elasticity of anionic and cationic HVFRs comparably and precisely with experimental variables well controlled. Two hypotheses based on anions and cations’ effects on the viscosity of HVFRs are proposed and will be tested in this study. First, the elasticity reduction of anionic HVFRs is mainly due to cations, whereas the elasticity reduction of cationic HVFRs is mainly due to anions. Second, the salts’ effects on the elasticity reduction of HVFRs should follow the same trend as the salts’ effects on the viscosity reduction of HVFRs. For anionic HVFRs, monovalent Alkali metals should have a similar effect; divalent Alkaline earth metals should have a similar effect; transition metals should have the most severe effect. For cationic HVFRs, SO42- should have more pronounced effects than Cl-. To demonstrate both hypotheses, an anionic and a cationic HVFR at 4 gallons per thousand gallons (GPT) were selected and analyzed. The elasticity measurements of both anionic and cationic HVFRs were conducted with deionized (DI) water and various salts respectively. Fe3+ and H+ (or pH) effects were specifically investigated. The results showed both hypotheses were accepted.
APA, Harvard, Vancouver, ISO, and other styles
5

Mosses, R. W., J. P. R. Wells, T. P. J. Han, H. G. Gallagher, and M. Yamaga. "Spectroscopy of Rare-Earth Doped Perovskite Phase Strontium Lanthanum Aluminate." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cthh47.

Full text
Abstract:
Strontium lanthanum aluminate (SrLaAlO4) belongs to a wide family of compounds with the general formula ABCO4 (where A denotes an alkaline earth cation: B denotes Y. Sc or a trivalent rare earth element and C denotes Al, Ga or a transition metal ion). This material crystallises in the perovskite phase, with tetragonal K2NiF4 structure having space group 14/mmm. The structure is composed of CO6 layers in the ab plane. The C cations are surrounded by six oxygens and sit in slightly distorted octahedral sites. Between these layers, the A cations and trivalent B cations are randomly distributed in nine co-ordinated sites of C4v symmetry. The random distribution of Sr2+ and La3+ ions leads to a structural disorder that causes inhomogeneous broadening of the spectral lines of rare-earth ions doped into these crystals.
APA, Harvard, Vancouver, ISO, and other styles
6

"Computational study of CO2 solubility in amino acid-based ionic liquids using COSMO-RS." In Sustainable Processes and Clean Energy Transition. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902516-33.

Full text
Abstract:
Abstract. The carbon capture, use, and sequestration (CCUS) techniques are proven to be efficient at lowering the atmospheric concentration of carbon dioxide. Notwithstanding the advances in this area, there are still significant restrictions in carbon dioxide (CO2) capture techniques in industry such as high capital costs, solvent evaporation losses, and low absorption and desorption rates. Ionic liquids (ILs) have received much interest as green solvent due to the benefits of their distinctive properties such as low vapor pressure and their capacity to capture CO2 making them a suitable replacement for present solvents, such as amines. Amino acid based ILs having close similarity with the alkanolamines may potentially have high affinity for CO2 absorption. Nevertheless, available database on these ILs is still limited and only focus on the common types of amino acids. Therefore, this paper aims to predict the CO2 absorption of different amino acid-based ionic liquids as cation/anion using quantum chemical calculation tools namely Conductor like Screening Model for Real Solvents (COSMO-RS) and TURBOMOLE. We evaluated 84 different ILs of different cations and anions based on their CO2 capacity, activity coefficient at infinite dilution (γ∞), and Henry’s constant (H). The results showed that amino acid as anions significantly enhanced the CO2 solubility compared to amino acid as cations. However, glycinium tetrafluoroborate [Gly+][BF4] showed high affinity for CO2 absorption compared to other amino acid-cations based with activity coefficient at infinite dilution (γ∞) = 0.117 and (H) = 8.07. We showed that the selection of anions/cations can significantly change the CO2 capacity in ILs.
APA, Harvard, Vancouver, ISO, and other styles
7

Kazemian, H., H. Ghasemi Mobtaker, M. H. Mallah, M. Motamedi, M. Abbas Mohsen, and A. M. Nejad. "Enhancing the Sorption of Uranyl Ions in the Presence of Carbonate Ions on Zeolite and Mesoporous Materials." In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4637.

Full text
Abstract:
In this study the effect of carbonate concentration on the sorption of uranyl ion from wastewaters was investigated. In the presence of carbonate ions, uranyl cation form a stable anionic complex which disturbs the removal of uranyl by cation exchangers such as zeolite P and A. These zeolites were loaded with some cations and investigated for the sorption of the complex. The sorption of uranyl by a surfactant-modified zeolite was investigated too. Because of low selectivity of these samples, a MCM-41/ZSM-5 composite was synthesized and loaded with a cation and the sorption of mentioned complex by composite was also investigated and the results were promising.
APA, Harvard, Vancouver, ISO, and other styles
8

Naruphontjirakul, Parichart. "Cations doped nonporous silica nanoparticles." In 2019 12th Biomedical Engineering International Conference (BMEiCON). IEEE, 2019. http://dx.doi.org/10.1109/bmeicon47515.2019.8990288.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Yoshihara, K., A. Douhal, Y. Nagasawa, A. Yartzev, H. Kandori, and K. Kenmitz. "Femtosecond intermolecular electron transfer : dye in weakly polar electron-donating solvent." In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.md1.

Full text
Abstract:
Ultrafast intermolecular electron transfer (0.1-0.2 ps) was observed for xantheme dyes in electron-donating solvents. Rates were limited by ultrafast nuclear relaxation not by solvent longitudinal relaxation, (470 mn) and AN (405 nm) and DMA (470 nm) cations in the subpicosecond timescale. From the recovery of ground-state depletion and decay of cation radicals, the reverse ET was also found to be fast, i.e., 4.0 ps in NB/DMA and 2.7 ps in NB/AN.
APA, Harvard, Vancouver, ISO, and other styles
10

Wang, Xuezheng, and Elisabeth Smela. "Cycling conjugated polymers with different cations." In Smart Structures and Materials, edited by Yoseph Bar-Cohen. SPIE, 2006. http://dx.doi.org/10.1117/12.658057.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Cations"

1

Werst, D. W. Arene-thioether mixed complex radical cations. Office of Scientific and Technical Information (OSTI), March 1994. http://dx.doi.org/10.2172/10132711.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Mincher, Bruce J., Christopher A. Zarzana, and Stephen P. Mezyk. Radical Cations and Acid Protection during Radiolysis. Office of Scientific and Technical Information (OSTI), September 2016. http://dx.doi.org/10.2172/1389193.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Christe, Karl, Ashwani Vij, Fook S. Tham, Vandana Vij, and William W. Wilson. Structures of the BrF4(+) and IF4(+) Cations. Fort Belvoir, VA: Defense Technical Information Center, August 2002. http://dx.doi.org/10.21236/ada406379.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Wicker, Louise, Ilan Shomer, and Uzi Merin. Membrane Processing of Citrus Extracts: Effects on Pectinesterase Activity and Cloud Stability. United States Department of Agriculture, October 1993. http://dx.doi.org/10.32747/1993.7568754.bard.

Full text
Abstract:
The U.S. team studied the role of cations and pH on thermolabile (TL-PE) and thermostable (TS-PE), permeation in ultrafiltration (UF) membranes, affinity to ion exchange membranes, mechanism of cation and pH activation, and effect on PE stability. An optimum pH and cation concentration exists for activity and UF permeation, which is specific for each cation type. Incomplete release of PE from a pectin complex resulted in low PE binding to cationic and anionic membranes. Incubation of PE at low pH increases the surface hydrophobicity, especially TL-PE, but the secondary structure of TL-PE is not greatly affected. The Israeli team showed that stable cloud colloidal constituents flocculate following the conversion of soluble to insoluble biopolymers. First, formation of pectic acid by pectinesterase activity is followed by the formation of calcium pectate gel. This process initiates a myriad of poorly defined reactions that result in juice clarification. Second, protein coagulation by heat resulted in flocculation of proteinacous bound cloud constituents, particularly after enzymatic pectin degradation. Pectinesterase activity is proposed to be an indirect cause for clarification; whereas binding of cloud constituents is the primary event in clarification by pectate gel and coagulated proteins. Understanding the mechanism of interaction of protein and pectic polymers is key to understanding cloud instability. Based on the above, it was hypothesized that the structure of pectin-protein coagulates plays a key role in cloud instability.
APA, Harvard, Vancouver, ISO, and other styles
5

Barnabas, M. V., and A. D. Trifunac. Radical cations of quadricyclane and norbornadiene in polar ZSM-5 matrices: Radical cation photochemical transformations without photons. Office of Scientific and Technical Information (OSTI), June 1994. http://dx.doi.org/10.2172/10161026.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Taylor-Pashow, K., and D. Hobbs. EFFECT OF CATIONS ON ALUMINUM SPECIATION UNDER ALKALINE CONDITIONS. Office of Scientific and Technical Information (OSTI), July 2012. http://dx.doi.org/10.2172/1050619.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Zhang, Zhouhong, and Changjian Lin. Diffusion of cations beneath organic coatings on steel substrate. Gaithersburg, MD: National Institute of Standards and Technology, 1993. http://dx.doi.org/10.6028/nist.ir.5102.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

McQuaid, Michael J., and Gregory W. Drake. Property Predictions for Nitrate Salts with Nitroxy-Functionalized Cations. Fort Belvoir, VA: Defense Technical Information Center, May 2011. http://dx.doi.org/10.21236/ada550658.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Daniel T. Schwartz, Bekki Liu, Marlina Lukman, Kavita M. Jeerage, William A. Steen, Haixia Dai, Qiuming Yu, and J. Antonio Medina. Potential Modulated Intercalation of Alkali Cations into Metal Hexacyanoferrate Coated Electrodes. Office of Scientific and Technical Information (OSTI), February 2002. http://dx.doi.org/10.2172/792792.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Schwartz, Daniel T. Potential Modulated Intercalation Of Alkali Cations Into Metal Hexacyanoferrate Coated Electrodes. Office of Scientific and Technical Information (OSTI), June 2000. http://dx.doi.org/10.2172/828572.

Full text
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Cations' for particular source types:
Journal articles Dissertations / Theses Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography