Donor numbers: 27Al quadrupole relaxation as a measure of solvent donicity towards the sodium ion

1983 ◽  
Vol 61 (8) ◽  
pp. 1719-1721 ◽  
Author(s):  
Marion C. Day ◽  
James H. Medley ◽  
Naseer Ahmad
Keyword(s):  
Sodium Ion ◽  
New Method ◽  
Quadrupole Relaxation ◽  
Solvent Interactions ◽  
Donor Numbers ◽  
Line Widths ◽  
The Stability ◽  
Anion Interaction ◽  
Solvent Solvent

A new method is presented for the determination of solvent donicity towards the sodium ion that avoids solvent–solvent interactions. Using the systemNaAlEt4–benzene–donorthe response of the 27Al quadrupole relaxation to anion symmetry as a function of donor: Na+ ratio is monitored by both 27Al line widths and methylene 1H absorptions. The assumption is made that anion symmetry is dependent on the cation–anion interaction which is dependent on the stability of the donor–Na+ solvates. The ordering of donors is found to differ from the generally accepted listing. A ranking of seventeen donors is given.

scholarly journals Determination of Objective Weights Using a New Method Based on the Removal Effects of Criteria (MEREC)

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 525 ◽  
Author(s):  
Mehdi Keshavarz-Ghorabaee ◽  
Maghsoud Amiri ◽  
Edmundas Kazimieras Zavadskas ◽  
Zenonas Turskis ◽  
Jurgita Antucheviciene
Keyword(s):  
Essential Elements ◽  
New Method ◽  
Multi Criteria Decision Making ◽  
Analysis Of Means ◽  
Simulation Based ◽  
Criteria Weights ◽  
The Stability ◽  
Computational Analyses ◽  
Weighting Methods

The weights of criteria in multi-criteria decision-making (MCDM) problems are essential elements that can significantly affect the results. Accordingly, researchers developed and presented several methods to determine criteria weights. Weighting methods could be objective, subjective, and integrated. This study introduces a new method, called MEREC (MEthod based on the Removal Effects of Criteria), to determine criteria’ objective weights. This method uses a novel idea for weighting criteria. After systematically introducing the method, we present some computational analyses to confirm the efficiency of the MEREC. Firstly, an illustrative example demonstrates the procedure of the MEREC for calculation of the weights of criteria. Secondly, a comparative analysis is presented through an example for validation of the introduced method’s results. Additionally, we perform a simulation-based analysis to verify the reliability of MEREC and the stability of its results. The data of the MCDM problems generated for making this analysis follow a prevalent symmetric distribution (normal distribution). We compare the results of the MEREC with some other objective weighting methods in this analysis, and the analysis of means (ANOM) for variances shows the stability of its results. The conducted analyses demonstrate that the MEREC is efficient to determine objective weights of criteria.

New method for the determination of the stability constants of coordination compounds

1958 ◽  
Vol 8 ◽  
pp. 332-339 ◽  
Author(s):  
Sergio Cabani ◽  
Eolo Scrocco
Keyword(s):  
Stability Constants ◽  
Coordination Compounds ◽  
New Method ◽  
The Stability

THE NEW METHOD FOR DETERMINATION OF THE STABILITY CONSTANTS OF CYCLODEXTRIN–PROSTAGLANDIN INCLUSION COMPLEXES BY LIQUID CHROMATOGRAPHY

1978 ◽  
Vol 7 (7) ◽  
pp. 661-664 ◽  
Author(s):  
Kaneto Uekama ◽  
Fumitoshi Hirayama ◽  
Tetsumi Irie
Keyword(s):  
Liquid Chromatography ◽  
Inclusion Complexes ◽  
Stability Constants ◽  
New Method ◽  
The Stability

23Na nuclear magnetic resonance linewidth studies of sodium tetraethylaluminate: complexes with hexamethylphosphoramide in benzene

1983 ◽  
Vol 61 (3) ◽  
pp. 558-561 ◽  
Author(s):  
James Harold Medley ◽  
Eddie Steven Mooberry ◽  
Marion Clyde Day
Keyword(s):  
Ion Pair ◽  
Sodium Ion ◽  
Complexing Agent ◽  
Solvation Number ◽  
Quadrupole Relaxation ◽  
Solvation Numbers ◽  
Nuclear Quadrupole ◽  
Anion Distance ◽  
Nuclear Quadrupole Relaxation

The linewidth of the 23Na resonance in sodium tetraethylaluminate in benzene has been measured as a function of the ratio of [donor]: [Na+] using the strong complexing agent hexamethylphosphoramide. In this system changes in the sodium linewidth arise primarily from changes in the nuclear quadrupole relaxation at the sodium nucleus which in turn arise from changes in the electric field gradient. As the ratio of hexamethylphosphoramide to sodium ion is increased up to 3: 1 the 23Na linewidth progressively decreases due to an increase in cation–anion distance in the ion pair. After a ratio of 4:1 is reached, essentially no linewidth change is noted, indicating a stable solvation number of 4 for hexamethylphosphoramide. The results of this study indicate that this is a new and promising approach to the determination of solvation numbers of the sodium ion.

New Method for Rapid Determination of Carboxyhemoglobin by Use of Double-Wavelength Spectrophotometry

1974 ◽  
Vol 20 (2) ◽  
pp. 278-281 ◽  
Author(s):  
Alfred Ramieri ◽  
Peter Jatlow ◽  
David Seligson
Keyword(s):  
Carbon Monoxide ◽  
Rapid Determination ◽  
New Method ◽  
Reduction Procedure ◽  
Simple Method ◽  
Absorption Signal ◽  
The Stability

Abstract We have developed a simple method for rapid determination of carboxyhemoglobin concentration in blood, by use of double-wavelength spectrophotometry. The absorbance of both oxyhemoglobin and reduced hemoglobin are instrumentally nulled out in this procedure, so that the absorption signal reflects HbCO and only a single spectrophotometric reading is required. This procedure is accurate in the range encountered in ambulatory persons as well as in the "toxic" range. Results correlated well with the dithionite reduction procedure. The stability of carboxyhemoglobin in solution was investigated and concentrations of carbon monoxide in groups of smokers and nonsmokers were determined.

A new method for the determination of nitrates

1960 ◽  
Vol 23 ◽  
pp. 227-232 ◽  
Author(s):  
P WEST ◽  
G LYLES
Keyword(s):  
New Method

A New Method for the Determination of Plasma Activators of Fibrinolysis

1977 ◽  
Vol 37 (02) ◽  
pp. 210-215 ◽  
Author(s):  
R Margalit ◽  
E Gidron ◽  
Y Shalitin
Keyword(s):  
New Method ◽  
Effective Activator

SummaryThe term “effective activator” of plasminogen is proposed, to denote the resultant of activator-antiactivator interaction, and a method for the determination of the level of these activators is described. By adding axcess plasminogen to the euglobulin fraction of plasma the influence of the level of endogenous plasminogen and of the antiplasmin is eliminated. It is shown that the level of fibrinogen has very little bearing on the results. An effective activator unit is defined as equal to 1 CTA unit of urokinase activity on a fibrinogen-plasminogen substrate.

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