Extrapolation from concentrated to dilute aqueous acids

1983 ◽  
Vol 61 (2) ◽  
pp. 249-256 ◽  
Author(s):  
A. J. Kresge ◽  
H. J. Chen ◽  
G. L. Capen ◽  
M. F. Powell
Keyword(s):  
Function Method ◽  
Limited Range ◽  
Acidity Function ◽  
Dilute Solution ◽  
Concentrated Solutions ◽  
Acidity Functions ◽  
Aqueous Hclo ◽  
Made In

The location and the manner of union of the H0 and HR acidity functions with −log [Formula: see text] have been determined for aqueous HClO4, HCl, and H2SO4 (H0 only) through particularly careful and extensive indicator measurements in dilute and moderately concentrated solutions of these acids. These data were also used to evaluate and compare a number of different ways of extrapolating measurements made in concentrated acids down to dilute solution; over the limited range of acidity investigated, the traditional acidity function method, as commonly applied in the absence of an appropriate acidity function (i.e. in the form of mH0), was found to be the least satisfactory of these extrapolative methods, and the Cox–Yates technique was found to be the best.

DISCUSSION ON THE USE OF HEXACHLOROPHENE IN THE NURSERY

PEDIATRICS ◽  
1973 ◽  
Vol 51 (2) ◽  
pp. 406-412
Keyword(s):  
Preliminary Data ◽  
Artificial Ventilation ◽  
Newborn Infants ◽  
Study Group ◽  
Dilute Solution ◽  
Neurological Manifestations ◽  
Intact Skin ◽  
Special Diets ◽  
Made In

Discussion–following papers by Kimbrough, Mullick and Gluck Richard Davis, USC: We have been examining brain sections from infants who have died in our nursery. So far we have found five cases similar to those described by Dr. Lampert. However, they occurred both during the period when hexachlorophene was being used as well as after its use had been discontinued. Dr. Shinefield: What was the concentration of hexachlorophene used? Dr. Davis: One teaspoon of 3% hexachlorophene in a quart of water. Moderator: With such a dilute solution, the amount of hexachborophene actually administered must have been very small. This raises the question as to whether the treated infants form a suitable study group. Dr. Alan Hodson: We have 10 cases showing striking bilateral and symmetrical vacuobation in myelinated areas; six were newborn infants and four were dermatobogical cases. The newborn infants were all immature (27 to 34 weeks' gestation) and received daily baths of 3% hexachiorophene for approximately 8 days. They were selected from 40 infants who died between 1967 and 1971. None of the infants was asphyxiated at birth and none required artificial ventilation. These are preliminary data and we do not yet know what the incidence of these lesions might have been before hexachlorophene bathing was introduced. Dr. Finberg: I would bike to report an observation recently made in Peru which might be a description of chronic hexachborophene toxicity following absorption of the chemical through the intact skin. In a unit established to study nutritional problems in children with severe marasmic kwashiarkor, the children were noted to become lethargic, vomit, and develop neurological manifestations when on special diets.

THE CONDUCTANCES OF STRONG SOLUTIONS OF STRONG ELECTROLYTES AT 95°

1952 ◽  
Vol 30 (2) ◽  
pp. 128-134 ◽  
Author(s):  
A. N. Campbell ◽  
E. M. Kartzmark
Keyword(s):  
Silver Nitrate ◽  
Ammonium Nitrate ◽  
Strong Solutions ◽  
Partial Molar Volumes ◽  
Concentrated Solutions ◽  
Temperature Coefficients ◽  
Equivalent Conductance ◽  
Strong Electrolytes ◽  
Made In ◽  
Nitrate Solutions

Measurements of conductance and fluidity of silver nitrate and of ammonium nitrate solutions, over a range of concentration varying from 0.05  N to 14  N (silver nitrate) and from 0.08  N to 15  N (ammonium nitrate) have been made. In both cases, a maximum is observed in the specific conductances but in neither case does a minimum occur in the plot of equivalent conductance against concentration. While the equivalent conductance in very dilute solutions is proportional to [Formula: see text], in very concentrated solutions it appears to be directly proportional to C. Temperature coefficients of conductance and of fluidity are evaluated and their theoretical importance discussed. Partial molar volumes of water in these solutions are evaluated.

scholarly journals MEEF: A Minimum-Elimination-Escape Function Method for Multimodal Optimization Problems

2015 ◽  
Vol 2015 ◽  
pp. 1-16
Author(s):  
Lei Fan ◽  
Yuping Wang ◽  
Xiyang Liu ◽  
Liping Jia
Keyword(s):  
Function Method ◽  
Optimization Problems ◽  
Auxiliary Function ◽  
Local Optimum ◽  
Multimodal Optimization ◽  
Optimal Solutions ◽  
Mexican Hat ◽  
Global Optimal ◽  
Elimination Function ◽  
Made In

Auxiliary function methods provide us effective and practical ideas to solve multimodal optimization problems. However, improper parameter settings often cause troublesome effects which might lead to the failure of finding global optimal solutions. In this paper, a minimum-elimination-escape function method is proposed for multimodal optimization problems, aiming at avoiding the troublesome “Mexican hat” effect and reducing the influence of local optimal solutions. In the proposed method, the minimum-elimination function is constructed to decrease the number of local optimum first. Then, a minimum-escape function is proposed based on the minimum-elimination function, in which the current minimal solution will be converted to the unique global maximal solution of the minimum-escape function. The minimum-escape function is insensitive to its unique but easy to adopt parameter. At last, an minimum-elimination-escape function method is designed based on these two functions. Experiments on 19 widely used benchmarks are made, in which influences of the parameter and different initial points are analyzed. Comparisons with 11 existing methods indicate that the performance of the proposed algorithm is positive and effective.

scholarly journals The analysis of intermolecular interactions in concentrated hyaluronan solutions suggest no evidence for chain–chain association

2000 ◽  
Vol 350 (1) ◽  
pp. 329-335 ◽  
Author(s):  
Phillip GRIBBON ◽  
Boon Chin HENG ◽  
Timothy E. HARDINGHAM
Keyword(s):  
Fluorescence Recovery After Photobleaching ◽  
Hydrodynamic Radius ◽  
Hydrophobic Interactions ◽  
Lateral Diffusion ◽  
Tracer Diffusion ◽  
Dilute Solution ◽  
Concentrated Solutions ◽  
Chain Flexibility ◽  
Self Diffusion ◽  
Confocal Fluorescence

Confocal fluorescence recovery after photobleaching (confocal-FRAP) was used to examine the influence of electrolytes (NaCl, KCl, MgCl2, MnCl2 and CaCl2) on the network and hydrodynamic properties of fluoresceinamine-labelled hyaluronan (FA-HA) at concentrations up to 10mg/ml. Self and tracer lateral diffusion coefficients showed that in Ca2+ and Mn2+, FA-HA (830kDa) was more compact than in Mg2+, Na+ or K+. These results were correlated with changes in the hydrodynamic radius of HA, determined by multi-angle laser-light-scattering analysis in dilute solution, which was smaller in CaCl2 (36nm) than in NaCl (43nm). The permeability of more concentrated solutions of HA (< 10mg/ml) to FITC-dextran tracers (2000kDa) was higher in CaCl2. The properties of HA in urea (up to 6M) were investigated to test for hydrophobic interactions and also in ethanol/water (up to 62%, v/v). In both, there was reduced hydrodynamic size and increased permeability to FITC-dextran, suggesting increased chain flexibility, but it did not show the changes predicted if chain–chain association was disrupted by urea, or enhanced by ethanol. Oligosaccharides of HA (HA20–26) also had no effect on the self diffusion of high-molecular-mass FA-HA (830kDa) solutions, or on dextran tracer diffusion, showing that there were no chain–chain interactions open to competition by short-chain segments. The results suggest that the effects of electrolytes and solvent are determined primarily by their effect on HA chain flexibility, with no evidence for association between chain segments contributing significantly to the major properties.

Increase in intake with sham feeding experience is concentration dependent

1999 ◽  
Vol 277 (2) ◽  
pp. R565-R571 ◽  
Author(s):  
John D. Davis ◽  
Gerard P. Smith ◽  
Bramdeo Singh ◽  
Daniel P. McCann
Keyword(s):  
Gastrointestinal Tract ◽  
Negative Feedback ◽  
The Other ◽  
Feedback Signal ◽  
Dilute Solution ◽  
Concentrated Solutions ◽  
Sweetened Condensed Milk ◽  
Sham Feeding ◽  
Feeding Experience ◽  
Condensed Milk

Most sham feeding studies show that about three sham feeding tests are required for intake to reach maximum. One study, however, using a dilute solution, reported maximum sham intake in the first sham feeding test, suggesting that the progressive rise in sham intake may be concentration dependent. We tested this hypothesis with six groups of rats given five sham feeding tests each with one of six concentrations of sweetened condensed milk (0.5:1, 1:1, 2:1, 4:1, 8:1, 16:1, water-to-milk dilutions). It took three sham tests for intake to reach maximum with the three most concentrated solutions, but only one with the three weakest. Thus the intake of concentrated solutions of milk is limited by two negative feedback signals, one derived from the accumulation of fluid in the gastrointestinal tract, the other from a labile signal that loses its effectiveness with sham feeding experience. In contrast, the intake of weak concentrations is limited only by the nonlabile negative feedback signal because the labile signal is missing.

Die Abhängigkeit der Fluoreszenzquantenausbeute von der Anregungswellenlänge bei Carbonylverbindungen des Pyrens

1974 ◽  
Vol 29 (5) ◽  
pp. 804-809
Author(s):  
P. Kröning
Keyword(s):  
Wave Length ◽  
Intermolecular Forces ◽  
Short Wave ◽  
Dilute Solution ◽  
Concentrated Solutions ◽  
Polar Solvents ◽  
Excitation Wave ◽  
Long Wave ◽  
Weak Intermolecular Forces ◽  
Monomer Fluorescence

Abstract Pyrene-3-aldehyde, 3-acetylpyrene and 3-benzoylpyrene show almost no fluorescence in dilute solution in non-polar solvents. In more concentrated solutions, however, a long wave fluorescence is observed, showing the existence of weak intermolecular forces, even in the ground state. In polar solvents, pyrene-3-aldehyde and 3-acetylpyrene exhibit short wave monomer fluorescence whilst 3-benzoylpyrene does not fluoresce. The intensity for both long and short wave fluorescence is dependent upon the excitation wave length and is a maximum for excitation in the weak long wave tail of the first absorption band. Molecules are thought to have a greater absorption in this region if they interact strongly with their polar or polarizable surroundings. Due to the very short singlet lifetime of isolated monomers (τ<C10-10 sec), such molecules have a greater probability of forming a fluorescence state than more weakly interacting ones.

scholarly journals A Laser Photolysis Study of Triplet Lifetimes and of Triplet–Triplet Annihilation Reactions of Phthalocyanins in DMSO Solutions (Etude des Durées de Vie du Triplet et des Réactions d'Annihilation Triplet–Triplet de Phthalocyanines dans le DMSO par Photolyse Laser)

1988 ◽  
Vol 8 (1) ◽  
pp. 1-11 ◽  
Author(s):  
M. G. Debacker ◽  
O. Deleplanque ◽  
B. Van Vlierberge ◽  
F. X. Sauvage
Keyword(s):  
Charge Separation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Reducing Agent ◽  
Dilute Solution ◽  
Concentrated Solutions ◽  
Decay Mechanism ◽  
First Order ◽  
Annihilation Reactions

Triplet decay of Mg and Zn phthalocyanins have been studied by laser flash photolysis as a function of concentration. The triplet decay mechanism changes from a near first order in dilute solution to an almost second order in concentrated solutions. This is interpreted in terms of triplet–triplet recombinaison. With the help of a reducing agent, it is shown that the triplet–triplet reaction can lead to charge separation.La décroissance des états excités triplet des phthalocyanines de Mg et de Zn a été étudiée par photolyse éclair laser en fonction de la concentration. Le mécanisme de décroissance du triplet passe d'un premier ordre presque idéal en solution diluée à un quasi second ordre en solution concentrée. Ceci s'explique par une recombinaison triplet–triplet. A l'aide d'un réducteur, la réaction triplet–triplet peut conduire à une séparation de charges.

IONIZATION OF ORGANIC COMPOUNDS: II. THIOACETAMIDE IN AQUEOUS SODIUM HYDROXIDE. THE H− ACIDITY FUNCTION

1962 ◽  
Vol 40 (3) ◽  
pp. 399-407 ◽  
Author(s):  
J. T. Edward ◽  
I. C. Wang
Keyword(s):  
Sodium Hydroxide ◽  
Organic Compounds ◽  
Aqueous Sodium Hydroxide ◽  
Ion Concentration ◽  
Acidity Function ◽  
Concentrated Solutions ◽  
Salting Out ◽  
Hydroxide Ion ◽  
Aqueous Sodium ◽  
Ionization Ratio

The ionization ratio of thioacetamide in aqueous sodium hydroxide, determined spectrophotometrically, is proportional to the concentration of hydroxide ion up to a concentration of about 1 M, and indicates a pKHA of 13.4. For more concentrated solutions the ionizing power increases more rapidly than the hydroxide ion concentration; from the experimentally determined ionization ratios the values of the h− acidity function for 1–6 M sodium hydroxide have been calculated. The relation of h− values to the salting-out parameters and water activities of concentrated sodium hydroxide solutions is discussed.

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