The role of intermolecular forces in ionic reactions: the solvent effect, ion-pairing, aggregates and structured environment

2021 ◽  
Author(s):  
Josefredo R. Pliego
Keyword(s):  
Solvent Effect ◽  
Ion Pairing ◽  
Intermolecular Forces ◽  
General View ◽  
Medium Effects ◽  
Ionic Reactions

A general view of the medium effects on ionic reactions involves the solvent effect, ion pairing, formation of aggregates and structured environment.

scholarly journals Influence of the Electrolyte Salt Concentration on DNA Detection with Graphene Transistors

Biosensors ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 24
Author(s):  
Agnes Purwidyantri ◽  
Telma Domingues ◽  
Jérôme Borme ◽  
Joana Rafaela Guerreiro ◽  
Andrey Ipatov ◽  
...  
Keyword(s):  
Phosphate Buffer ◽  
Species Interactions ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Limit Of Detection ◽  
Debye Length ◽  
Intermolecular Forces ◽  
Single Layer Graphene ◽  
Dna Adsorption

Liquid-gated Graphene Field-Effect Transistors (GFET) are ultrasensitive bio-detection platforms carrying out the graphene’s exceptional intrinsic functionalities. Buffer and dilution factor are prevalent strategies towards the optimum performance of the GFETs. However, beyond the Debye length (λD), the role of the graphene-electrolytes’ ionic species interactions on the DNA behavior at the nanoscale interface is complicated. We studied the characteristics of the GFETs under different ionic strength, pH, and electrolyte type, e.g., phosphate buffer (PB), and phosphate buffer saline (PBS), in an automatic portable built-in system. The electrostatic gating and charge transfer phenomena were inferred from the field-effect measurements of the Dirac point position in single-layer graphene (SLG) transistors transfer curves. Results denote that λD is not the main factor governing the effective nanoscale screening environment. We observed that the longer λD was not the determining characteristic for sensitivity increment and limit of detection (LoD) as demonstrated by different types and ionic strengths of measuring buffers. In the DNA hybridization study, our findings show the role of the additional salts present in PBS, as compared to PB, in increasing graphene electron mobility, electrostatic shielding, intermolecular forces and DNA adsorption kinetics leading to an improved sensitivity.

Kinetics of Ion-Pair Effect of Aquation of Bromopentaammine Cobalt(III) Complex in Different Dicarboxylate Media

2011 ◽  
Vol 324 ◽  
pp. 166-169 ◽  
Author(s):  
Farah Zeitouni ◽  
Gehan El-Subruiti ◽  
Ghassan Younes ◽  
Mohammad Amira
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Compensation Effect ◽  
Ion Pairing ◽  
Reaction Rates ◽  
Ion Pair ◽  
Free Energy Of Activation ◽  
Different Types ◽  
Different Temperatures ◽  
Kinetics Of

The rate of aquation of bromopentaammine cobalt(III) ion in the presence of different types of dicarboxylate solutions containing tert-butanol (40% V/V) have been measured spectrophotometrically at different temperatures (30-600°C) in the light of the effects of ion-pairing on reaction rates and mechanism. The thermodynamic and extrathermodynamic parameters of activation have been calculated and discussed in terms of solvent effect on the ion-pair aquation reaction. The free energy of activation ∆Gip* is more or less linearly varied among the studied dicarboxylate ion-pairing ligands indicating the presence of compensation effect between ∆Hip* and ∆Sip*. Comparing the kip values with respect of different buffers at 40% of ter-butanol is introduced.

scholarly journals Investigation of the role of the C-PCM solvent effect in reactivity indices

2005 ◽  
Vol 117 (5) ◽  
pp. 583-589 ◽  
Author(s):  
Piotr Ordon ◽  
Akitomo Tachibana
Keyword(s):  
Solvent Effect ◽  
Reactivity Indices

scholarly journals B Chromosomes in Populations of Mammals Revisited

Genes ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 487 ◽  
Author(s):  
Mladen Vujošević ◽  
Marija Rajičić ◽  
Jelena Blagojević
Keyword(s):  
Mammalian Species ◽  
B Chromosome ◽  
Molecular Techniques ◽  
B Chromosomes ◽  
General View ◽  
Protein Coding ◽  
Host Parasite Interactions ◽  
Quantitative Characteristics ◽  
Host Parasite

The study of B chromosomes (Bs) started more than a century ago, while their presence in mammals dates since 1965. As the past two decades have seen huge progress in application of molecular techniques, we decided to throw a glance on new data on Bs in mammals and to review them. We listed 85 mammals with Bs that make 1.94% of karyotypically studied species. Contrary to general view, a typical B chromosome in mammals appears both as sub- or metacentric that is the same size as small chromosomes of standard complement. Both karyotypically stable and unstable species possess Bs. The presence of Bs in certain species influences the cell division, the degree of recombination, the development, a number of quantitative characteristics, the host-parasite interactions and their behaviour. There is at least some data on molecular structure of Bs recorded in nearly a quarter of species. Nevertheless, a more detailed molecular composition of Bs presently known for six mammalian species, confirms the presence of protein coding genes, and the transcriptional activity for some of them. Therefore, the idea that Bs are inert is outdated, but the role of Bs is yet to be determined. The maintenance of Bs is obviously not the same for all species, so the current models must be adapted while bearing in mind that Bs are not inactive as it was once thought.

ChemInform Abstract: A MCSCF Study of Homoaromaticity and the Role of Ion Pairing in the Stabilization of Carbanions.

ChemInform ◽  
1987 ◽  
Vol 18 (10) ◽  
Author(s):  
R. LINDH ◽  
B. O. ROOS ◽  
G. JONSAELL ◽  
P. AHLBERG
Keyword(s):  
Ion Pairing

Corrigendum: Counterion Specificity of Polyelectrolyte Brushes: Role of Specific Ion-Pairing Interactions

ChemPhysChem ◽  
2018 ◽  
Vol 19 (15) ◽  
pp. 1930-1930
Author(s):  
Ran Kou ◽  
Jian Zhang ◽  
Zhen Chen ◽  
Guangming Liu
Keyword(s):  
Ion Pairing ◽  
Polyelectrolyte Brushes ◽  
Pairing Interactions

Role of Intermolecular Forces in Defining Material Properties of Protein Nanofibrils

Science ◽  
2007 ◽  
Vol 318 (5858) ◽  
pp. 1900-1903 ◽  
Author(s):  
T. P. Knowles ◽  
A. W. Fitzpatrick ◽  
S. Meehan ◽  
H. R. Mott ◽  
M. Vendruscolo ◽  
...  
Keyword(s):  
Material Properties ◽  
Intermolecular Forces

Solvent effect on the conformational behavior of substituted spiro[4.5]decanes and spiro[5.5]undecanes

1995 ◽  
Vol 73 (5) ◽  
pp. 703-709 ◽  
Author(s):  
S. Sağ Erdem ◽  
T. Varnali ◽  
V. Aviyente ◽  
M.F. Ruiz-Lopez
Keyword(s):  
Solvent Effect ◽  
Electrostatic Interactions ◽  
Multipole Moment ◽  
Semiempirical Methods ◽  
Main Role ◽  
Solvent Interactions ◽  
Reaction Field ◽  
Solvent Models ◽  
Conformational Equilibria

We studied the relatively complex polar systems 6-substituted-1,4-dioxospiro[4.5]decanes and 7-substituted-1,5-dioxospiro[5.5]undecanes with substituents X = CH3, F, Cl, CN, OH, OCH3, and NO2. Solvent effects on the equilibrium have been analysed by means of a Self-Consistent-Reaction-Field model and the PM3 method. Complete geometry optimizations have been carried out for all the structures in the gas phase and in solution. For some substituents, a set of rotamers have been separately optimized. The discussion of the results is focussed on the effects arising from structural aspects and from steric and electrostatic interactions on the axial/equatorial relative stability. The role played by multipole moment is considered. In general, good agreement with available experimental data and with previous theoretical studies has been obtained. Though the use of semiempirical methods and simple solvent models prevents us from reaching definitive conclusions, this approach seems to be very useful in predicting the main role of solute–solvent interactions in conformational equilibria of complex systems for which ab initio calculations cannot be performed. Keywords: conformational equilibria, spiro decanes and undecanes, cavity model, SCRF, solvent effect, PM3 calculations.

The Ideology of the Letter of Aristeas

1958 ◽  
Vol 51 (2) ◽  
pp. 59-85 ◽  
Author(s):  
V. Tcherikover
Keyword(s):  
Special Kind ◽  
General View ◽  
Self Defense ◽  
Greek World

Modern scholars commonly regard the “Letter of Aristeas” as a work typical of Jewish apologetics, aiming at self-defense and propaganda, and directed to the Greeks. Here are some instances illustrating this general view. In 1903 Friedländer wrote that the glorification of Judaism in the Letter was no more than self-defense, though “the book does not mention the antagonists of Judaism by name, nor does it admit that its intention is to refute direct attacks.” Stein sees in the Letter “a special kind of defense which practices diplomatic tactics,” and Tramontano also speaks of “an apologetic and propagandist tendency.” Vincent characterizes it as “a small apologetic novel written for the Egyptians” (i.e. the Greeks in Egypt). Pfeiffer says: “This fanciful story of the origin of the Septuagint is merely a pretext for defending Judaism against its heathen denigrators, for extolling its nobility and reasonableness, and for striving to convert Greek speaking Gentiles to it.” Schürer classes the Letter with a special kind of literature, “Jewish propaganda in Pagan disguise,” whose works are “directed to the pagan reader, in order to make propaganda for Judaism among the Gentiles.” Andrews, too, believes that the role of a Greek was assumed by Aristeas in order “to strengthen the force of the argument and commend it to non-Jewish readers.” And even Gutman, who rightly recognizes that the Letter sprang “from an inner need of the educated Jew,” sees in it “a strong means for making Jewish propaganda in the Greek world.”

Effect of microtubule-destroying drugs on the spreading and shape of cultured epithelial cells

1985 ◽  
Vol 74 (1) ◽  
pp. 267-282
Author(s):  
L.V. Domnina ◽  
J.A. Rovensky ◽  
J.M. Vasiliev ◽  
I.M. Gelfand
Keyword(s):  
Glass Surface ◽  
Cell Shape ◽  
Medium Effects ◽  
Adhesive Surface ◽  
Lipid Films ◽  
Cultured Epithelial Cells ◽  
The Media ◽  
Glass Surfaces ◽  
Cytoplasmic Processes

The role of microtubules in the spreading of cells from the liver-derived IAR2 rat cell line was studied. Cells in the control medium seeded on a flat isotropic glass surface rapidly spread to form discoid shapes. Spreading in colcemid-containing medium was disorganized and delayed; partial reversal of spreading was observed. Nevertheless, even in the presence of colcemid the cells finally spread to discoid flattened shapes. IAR2 cells in medium without colcemid spread not to discoid but to elongated shapes under three different sets of conditions: (1) when the cells were forced to spread on narrow strips of adhesive glass surface between two non-adhesive lipid films; (2) when the cells spread on the poorly adhesive surface of poly(HEMA)-covered glass; (3) when the cells spread on the usual glass surfaces in medium containing cytochalasin D. Addition of colcemid to the media reversed the polarized spreading under the first two conditions; colcemid did not reverse the formation of the elongated cell shape acquired by the cells spreading in cytochalasin-containing medium. Effects of microtubule-destroying drugs on the spreading of epithelial and fibroblast cells are compared and discussed. It is suggested that microtubules are essential for the stabilization of the spread state of those attached cytoplasmic processes and lamellae that do not have numerous and stable-cell substratum contacts, e.g. the processes formed at the early stages of spreading or the elongated processes of polarized cells. Possibly, microtubules stabilize the non-contracted state of the actin cytoskeleton in these processes.

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