Rates of detritiation of the strychninesulfonic acids at the 11-position in alkaline solution

1984 ◽  
Vol 62 (11) ◽  
pp. 2448-2450 ◽  
Author(s):  
John T. Edward ◽  
Sin Cheong Wong ◽  
A. J. Kresge ◽  
M. F. Powell
Keyword(s):  
Ionic Strength ◽  
Sodium Hydroxide ◽  
Alkaline Solution ◽  
Reasonable Agreement ◽  
Sulfonate Group ◽  
Experimental Values

Tritium was incorporated into the 11-position of strychnine, and of strychninesulfonic acids-I, -II, and -III, and the rate of detritiation from the four compounds in 0.5 M sodium hydroxide at 25 °C was measured. Rates were reduced by the negative sulfonate groups, the extent of reduction varying inversely with the distance of the sulfonate group from the negative oxygen of the enolate intermediate. Experimental rates were in reasonable agreement with values expected at zero ionic strength from the Kirkwood–Westheimer equation. The problem of correcting experimental values for the effect of ionic strength is discussed.

The Effect of Dry Mix Sodium Hydroxide onto Workability and Compressive Strength of Geopolymer Paste

2020 ◽  
Vol 12 (9) ◽  
Author(s):  
A. Z. Mohd Ali ◽  
◽  
N. A. Jalaluddin ◽  
N. Zulkiflee ◽  
◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Alkaline Solution ◽  
High Emission ◽  
New Material ◽  
Curing Regime ◽  
Solid Form ◽  
Geopolymer Paste

The production of ordinary Portland cement (OPC) consumes considerable amount of natural resources, energy and at the same time contribute in high emission of CO2 to the atmosphere. A new material replacing cement as binder called geopolymer is alkali-activated concrete which are made from fly ash, sodium silicate and sodium hydroxide (NaOH). The alkaline solution mixed with fly ash producing alternative binder to OPC binder in concrete named geopolymer paste. In the process, NaOH was fully dissolved in water and cooled to room temperature. This study aims to eliminate this process by using NaOH in solid form together with fly ash before sodium silicate liquid and water poured into the mixture. The amount of NaOH solids were based on 10M concentration. The workability test is in accordance to ASTM C230. Fifty cubic mm of the geopolymer paste were prepared which consists of fly ash to alkaline solution ratio of 1: 0.5 and the curing regime of 80℃ for 24 hours with 100% humidity were implemented. From laboratory test, the workability of dry method geopolymer paste were decreased. The compressive strength of the dry mix of NaOH showed 55% and the workability has dropped to 58.4%, it showed strength reduction compared to the wet mix method.

scholarly journals Energetic Self-Folding Mechanism in α-Helixes

2019 ◽  
Author(s):  
Adolfo Bastida ◽  
José Zúñiga ◽  
Alberto Requena ◽  
Javier Cerezo
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy Surfaces ◽  
Reasonable Agreement ◽  
Dihedral Angles ◽  
Native Conformation ◽  
Experimental Values ◽  
Α Helix ◽  
Dynamics Simulations ◽  
Energy Surfaces ◽  
Large Peptide

A novel energetic route driving the folding of a polyalanine peptide from an extended conformation to its α-helix native conformation is described, supported by a new method to compute mean potential energy surfaces accurately in terms of the dihedral angles of the peptide chain from extensive Molecular Dynamics simulations. The Energetic Self-Folding (ESF) route arises specifically from the balance between the intrinsic propensity of alanine residues towards the α<sub>R </sub>conformation and two, opposite, effects: the destabilizing interaction with neighbor residues and the stabilizing formation of native hydrogen bonds, with the latter being dominant for large peptide lengths. The ESF mechanism provides simple but robust support to the nucleation-elongation, or zipper models, and offers a quantitative energetic funnel picture of the folding process. The mechanism is validated by the reasonable agreement between the computed folding energies and the experimental values.

The aggregation and reaction with oxygen of the tetrasodium salt of cobalt phthalocyanine-4,4',4'',4'''-tetrasulphonic acid

1973 ◽  
Vol 26 (2) ◽  
pp. 319 ◽  
Author(s):  
LC Gruen ◽  
RJ Blagrove
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Molecular Oxygen ◽  
Absorption Spectra ◽  
Alkaline Solution ◽  
Cobalt Phthalocyanine ◽  
Visible Absorption ◽  
Reversible Addition ◽  
Dimeric Form ◽  
Low Ionic Strength

The reversible addition of molecular oxygen to the tetrasodium salt of cobalt phthalocyanine-4,4?,4?,4??-tetrasulphonic acid in aqueous solution has been confirmed. Visible absorption spectra of the monomeric and dimeric species and of the oxygen adduct have been determined. A monomer-dimer system prevails at neutral pH, low ionic strength, and low dye concentrations. The oxygen adduct and the dimeric form of the dye predominate in alkaline solution.

The Influence of Thermodynamic Properties of Alloys on Effective Interdiffusion Coefficients in Ternary Systems

2007 ◽  
Vol 263 ◽  
pp. 141-146 ◽  
Author(s):  
Ü. Ugaste ◽  
Tony Laas ◽  
T. Škled-Gorbatšova
Keyword(s):  
Thermodynamic Properties ◽  
Diffusion Coefficients ◽  
Reasonable Agreement ◽  
Ternary Systems ◽  
Tracer Diffusion ◽  
Diffusion Couples ◽  
Experimental Values ◽  
Tracer Diffusion Coefficients ◽  
Interdiffusion Coefficients ◽  
The Relationship

To prove the validity of Dayananda’s phenomenological model of interdiffusion in ternary systems the effective interdiffusion coefficients for a few diffusion couples in the system Cu-Ni-Fe, annealed at 1000 oC, are calculated on the basis of this model using available tracer diffusion and thermodynamic data. It is found that the calculated values of effective interdiffusion coefficients are in reasonable agreement with experimental values extracted independently from experimental concentration--penetration curves. Using the relationship between effective interdiffusion coefficients, tracer diffusion coefficients and thermodynamic factors, it is shown that thermodynamic properties of alloys play a significant role in interdiffusion processes in the system Cu-Fe-Ni.

Theoretical Investigations of the EPR Parameters of Ti3+ in Beryl Crystal

2006 ◽  
Vol 61 (5-6) ◽  
pp. 286-288 ◽  
Author(s):  
Wen-Chen Zheng ◽  
Qing Zhou ◽  
Xiao-Xuan Wu ◽  
Yang Mei
Keyword(s):  
Hyperfine Structure ◽  
Reasonable Agreement ◽  
Lattice Relaxation ◽  
Superposition Model ◽  
Theoretical Investigations ◽  
Local Lattice ◽  
Epr Parameters ◽  
Structure Constants ◽  
Experimental Values ◽  
Crystal Field Parameters

The EPR parameters (g factors gII, g⊥ and hyperfine structure constants AII, A⊥) of Ti3+ ion at the sixfold coordinated Al3+ site with trigonal symmetry in beryl crystal are calculated by the thirdorder perturbation formulas of 3d1 ions in a trigonal octahedron. In the calculations, the crystal-field parameters are obtained by the superposition model, and the impurity-induced local lattice relaxation (which is similar to that found for Fe3+ in beryl) is considered. The calculated EPR parameters (and also the optical spectra) are in reasonable agreement with the experimental values

Sulfate and Sulfuric Acid Resistance of Geopolymer Mortars Using Waste Blended Ash

2013 ◽  
Vol 61 (3) ◽  
Author(s):  
M. Aamer Rafique Bhutta ◽  
Nur Farhayu Ariffin ◽  
Mohd Warid Hussin ◽  
Nor Hasanah Abdul Shukor Lim
Keyword(s):  
Sulfuric Acid ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Alkaline Solution ◽  
Sodium Hydroxide Solution ◽  
Sodium Silicate Solution ◽  
Sulfate Solution ◽  
Mass Ratio ◽  
Palm Oil Fuel Ash ◽  
Fuel Ash

This paper presents the chemical resistance of geopolymer mortars prepared from the combination of palm oil fuel ash (POFA) and pulverized fuel ash (PFA) from agro–industrial waste as cement replacement and activated by alkaline solution. Alkaline solution was prepared by combining sodium silicate and sodium hydroxide. The concentration of alkaline solution used was 14 Molar. The optimum mix proportions of geopolymer mortars with PFA: POFA mass ratio of 70:30 was used together with alkaline solution. The ratio of sodium silicate solution–to–sodium hydroxide solution by mass was 2.5:1. The mass ratio of sand to blended ashes was 3:1. Test specimens 70×70×70 mm cube were prepared and cured at room temperature (28°C) for 28–d and heat–cured at 90°C for 24 h, respectively. Then specimens were exposed to 5% sodium sulfate solution and 2% sulfuric acid solution for 28–d, 56–d, 90–d, 180–d and 365–d .The evaluation was done by visual observation, mass change, and loss of compressive strength. The test results revealed that geopolymer mortars showed higher resistance to acids as compared to ordinary Portland cement mortar due to the elimination of cement in the mixture.

Calculation of Effect of Viscous and Pressure Forces on Trimming Moments

2014 ◽  
Vol 590 ◽  
pp. 42-47
Author(s):  
Salma Sherbaz ◽  
Wen Yang Duan
Keyword(s):  
Computational Methods ◽  
Reasonable Agreement ◽  
Volume Of Fluid ◽  
Wave Profile ◽  
Computational Domain ◽  
Implicit Methods ◽  
Ansys Fluent ◽  
Hull Form ◽  
Experimental Values

In this study the effects of viscous and pressure forces on trimming moments of Series 60 (CB = 0.6) hull form are calculated at different Froude numbers by employing computational methods. The grid generator GAMBIT was used for meshing hull and computational domain. The Simulations are carried out using commercial CFD code ANSYS Fluent 13. The SIMPLE (Semi-Implicit Methods for Pressure-Linked Equations) algorithm is used for pressure-velocity coupling. The volume of Fluid (VOF) formulation is employed. The computed resistance, wave profile and trim of series 60 hull are compared with experimental values and found in reasonable agreement.

Effects of Alkaline Solution on the Properties of Slag Based Geopolymer

2018 ◽  
Vol 877 ◽  
pp. 193-199 ◽  
Author(s):  
Suman Saha ◽  
C. Rajasekaran
Keyword(s):  
Compressive Strength ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Alkaline Solution ◽  
Sodium Hydroxide Solution ◽  
Setting Time ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Hydroxide Solution ◽  
Geopolymer Paste

Production of Ordinary Portland Cement (OPC) requires huge quantity of natural resources and energy and it releases large amount of carbon - di - oxide to the environment. Therefore, enormous studies have been carried out throughout the world to establish geopolymer as an alternative binder material for the replacement of OPC to protect the environment. This study intends to explore the effects of alkaline solution on the properties of geopolymer produced with ground granulated blast furnace slag. Properties such as Standard consistency, setting time of slag based geopolymer paste has been determined using Vicat’s apparatus (according to the guidelines given by Indian Standards for OPC). In order to determine the effects of alkaline solution on the properties of geopolymers, the concentration of sodium hydroxide solution has been varied from 6M to 16M and the ratio of sodium silicate solution to sodium hydroxide solution is also varied from 1.0 to 2.0. Results indicate higher standard consistency and significant less setting time for slag based geopolymer paste than that of OPC paste. Compressive strength of the geopolymer paste and mortar cube samples, cured in ambient conditions till the day of testing, is increasing with the increase of the concentration of sodium hydroxide solution. Highest compressive strength is obtained for the samples prepared with alkaline solution having the ratio of sodium silicate solution to sodium hydroxide solution as 1.5. But when the concentration of sodium hydroxide solution is beyond 14M, decreasing trend in compressive strength is observed.

scholarly journals THE IONIC ACTIVITY OF GELATIN

1928 ◽  
Vol 11 (5) ◽  
pp. 613-628 ◽  
Author(s):  
Henry S. Simms
Keyword(s):  
Ionic Strength ◽  
Acid Solution ◽  
Alkaline Solution ◽  
Physical Significance ◽  
The Other ◽  
Maximum Effect ◽  
Ionic Activity ◽  
Practical Utility ◽  
Weak Electrolytes ◽  
The Mean

2.5 and 1.25 per cent gelatin have been titrated potentiometrically in the absence of salts and in the presence of two concentrations (0.0750 and 0.0375µ) of NaCl, MgCl2, K2SO4, and MgSO4. The data have been used to calculate values of ± S = vz – (v – 1)z, where vz = v2 – (v2 – v) rx/18. The maximum and minimum values of S with NaCl were used to calculate the mean distance (rx) between like charges in gelatin. This is found to be 18 Å.u. or over (between acid or basic groups) which agrees with the probable value and the titration index dispersion. Thus the data with NaCl are shown to be normal and to obey the equation found to hold for simple weak electrolytes; namely, pK' – pK = Sa See PDF for Equation where S is related to the valence and distance by the above equations. Using the NaCl data as a standard the deviations (ΔS) produced by the other salts are calculated and are found to agree quantitatively with the deviations calculated from equations derived for the simple weak electrolytes. This shows that in gelatin, as in the simple electrolytes, the deviations are related to the "apparent valences" (values which are a function of the true valence and the distance between the groups). The maximum "apparent valences" of gelatin are 2.4 for acid groups (in alkaline solution) and 1.8 for basic groups (in acid solution). These values correspond to the hypothetical condition of zero distance between the groups. They have no physical significance but have a practical utility first as mentioned above, and second in that they may be used in the unmodified Debye-Hückel equation to give the maximum effect of gelatin on the ionic strength. The true effect is probably even lower than these values would indicate. The data indicate that gelatin is a weak polyvalent ampholyte having distant groups and that the molecule has an arborescent structure with interstices permeated by molecules of the solvent and other solutes. The size and shape probably vary with the pH.

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