scholarly journals The origin of multiply sigmoid curves of pH-dependence. The partitioning of groups among titration pK values

1991 ◽  
Vol 278 (1) ◽  
pp. 279-284 ◽  
Author(s):  
H B F Dixon ◽  
S D Clarke ◽  
G A Smith ◽  
T K Carne
Keyword(s):  
Titration Curve ◽  
Dissociation Constants ◽  
Ph Dependence ◽  
The Other ◽  
Equimolar Mixture ◽  
Ionization State ◽  
Degree Of Dissociation ◽  
Titration Curves ◽  
Ph Range ◽  
The One

An acid, HnA, with n ionizing groups is known to have the same titration curve as an equimolar mixture of n hypothetical monobasic acids, whose dissociation constants are known as the ‘titration constants’ of the real acid. We show that the pH-dependence of any property of HnA is also represented by the sum of one-site titration curves, characterized by these same titration constants. Since one such property is the degree of dissociation of one of the dissociating groups, a fraction of each group shows each of the various titration pK values, so that the group partitions among them. The n groups therefore share the same n titration pK values but differ in the fractions belonging to each. The one H+ ion per molecule that titrates with each pK is thus made up of the fractions, one from each group, that share this pK value. A group may possess a single pK value, in that it contributes virtually all of this pK and almost nothing to the others, only if either (1) in titrates in a different pH range from the other groups or (2) its affinity for H+ is unaffected by their ionization state.

Some Physicochemical Peculiarities of Poplar Plastocyanins a and b

2009 ◽  
Vol 64 (5-6) ◽  
pp. 399-404 ◽  
Author(s):  
Petya K. Christova ◽  
Anthony A. Donchev ◽  
Alexandra C. Shosheva ◽  
Vladimir I. Getov ◽  
Mitko I. Dimitrov
Keyword(s):  
Plant Species ◽  
Ph Dependence ◽  
Equilibrium Constants ◽  
The Other ◽  
Redox Potentials ◽  
Extinction Coefficients ◽  
Structural Differences ◽  
Ph Dependent ◽  
Ph Range ◽  
Reduced Forms

The redox potentials of poplar plastocyanins a and b (PCa, PCb) were determined by spectro photometric titrations of their reduced forms with [Fe(CN)6]3-. It was found that the two isoforms have the following millimolar extinction coefficients ε597, equilibrium constants Keq of one-electron exchange with [Fe(CN)6]4-/[Fe(CN)6]3-, and standard electron potentials E0′: PCa: ε597 = (4.72 ± 0.08) mM-1 cm-1, Keq = 0.133 ± 0.009, E0′ = (354 ± 11) mV; PCb: ε597 = (5.23 ± 0.16) mM-1 cm-1, Keq = 0.175 ± 0.010, E0′ = (363 ± 12) mV. The pH dependence of the redox potential of PCb was studied too. It was found, that the value of E0′ for PCb is constant in the pH range 6.5 - 9.5, but decreases in the range 4.8 - 6.5. On the whole, the dependence resembles that of PC from some well-known plant species, including poplar PCa. The changes of E0′ in the pH-dependent region for poplar PCb, however, are smaller and are 13 mV per pH unit, whereas in the other well-known plant species the changes are about 50 - 60 mV per pH unit. It has been assumed that the weaker pH dependence of E0′ of PCb accounts for some structural differences between PCa and PCb

scholarly journals Factors Influencing the Activity of Nanozymes in the Cleavage of an RNA Model Substrate

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2814 ◽  
Author(s):  
Czescik ◽  
Zamolo ◽  
Darbre ◽  
Mancin ◽  
Scrimin
Keyword(s):  
Gold Nanoparticles ◽  
Metal Complex ◽  
Kinetic Isotope Effect ◽  
Ph Dependence ◽  
The Other ◽  
Kinetic Isotope ◽  
Factors Influencing ◽  
Nitrophenyl Phosphate ◽  
The One ◽  
Guanidinium Cation

A series of 2-nm gold nanoparticles passivated with different thiols all featuring at least one triazacyclonanone-Zn(II) complex and different flanking units (a second Zn(II) complex, a triethyleneoxymethyl derivative or a guanidinium of arginine of a peptide) were prepared and studied for their efficiency in the cleavage of the RNA-model substrate 2-hydroxypropyl-p-nitrophenyl phosphate. The source of catalysis for each of them was elucidated from the kinetic analysis (Michaelis–Menten profiles, pH dependence and kinetic isotope effect). The data indicated that two different mechanisms were operative: One involving two Zn(II) complexes and the other one involving a single Zn(II) complex and a flanking guanidinium cation. The mechanism based on a dinuclear catalytic site appeared more efficient than the one based on the cooperativity between a metal complex and a guanidinium.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

Radioimmunotherapy for treatment of acute myeloid leukaemia and myelodysplastic syndrome

2005 ◽  
Vol 44 (03) ◽  
pp. 107-117
Author(s):  
R. G. Meyer ◽  
W. Herr ◽  
A. Helisch ◽  
P. Bartenstein ◽  
I. Buchmann
Keyword(s):  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Primary Tumour ◽  
The Other ◽  
Haematopoietic Stem Cell ◽  
Other Hand ◽  
Primary Reduction ◽  
The One ◽  
Acute Myeloid

SummaryThe prognosis of patients with acute myeloid leukaemia (AML) has improved considerably by introduction of aggressive consolidation chemotherapy and haematopoietic stem cell transplantation (SCT). Nevertheless, only 20-30% of patients with AML achieve long-term diseasefree survival after SCT. The most common cause of treatment failure is relapse. Additionally, mortality rates are significantly increased by therapy-related causes such as toxicity of chemotherapy and complications of SCT. Including radioimmunotherapies in the treatment of AML and myelodyplastic syndrome (MDS) allows for the achievement of a pronounced antileukaemic effect for the reduction of relapse rates on the one hand. On the other hand, no increase of acute toxicity and later complications should be induced. These effects are important for the primary reduction of tumour cells as well as for the myeloablative conditioning before SCT.This paper provides a systematic and critical review of the currently used radionuclides and immunoconjugates for the treatment of AML and MDS and summarizes the literature on primary tumour cell reductive radioimmunotherapies on the one hand and conditioning radioimmunotherapies before SCT on the other hand.

Das Ende der Postdemokratie, den Pessimismus überwinden.

2017 ◽  
Vol 47 (188) ◽  
pp. 487-494
Author(s):  
Daniel Mullis
Keyword(s):  
Political Thought ◽  
Social Dynamics ◽  
Social Conditions ◽  
The Other ◽  
Economic Decline ◽  
Far Right ◽  
Windows Of Opportunity ◽  
Political Events ◽  
Political Struggles ◽  
The One

In recent years, political and social conditions have changed dramatically. Many analyses help to capture these dynamics. However, they produce political pessimism: on the one hand there is the image of regression and on the other, a direct link is made between socio-economic decline and the rise of the far-right. To counter these aspects, this article argues that current political events are to be understood less as ‘regression’ but rather as a moment of movement and the return of deep political struggles. Referring to Jacques Ranciere’s political thought, the current conditions can be captured as the ‘end of post-democracy’. This approach changes the perspective on current social dynamics in a productive way. It allows for an emphasis on movement and the recognition of the windows of opportunity for emancipatory struggles.

Tolerance is theoretical and practical principles

1996 ◽  
pp. 13-23
Author(s):  
Mykhailo Babiy
Keyword(s):  
Religious Diversity ◽  
The Other ◽  
Nodal Points ◽  
Characteristic Features ◽  
The One ◽  
Ukrainian Society

Political ideological pluralism, religious diversity are characteristic features of modern Ukrainian society. On the one hand, multiculturalism, socio-political, religious differentiation of the latter appear as important characteristics of its democracy, as a practical expression of freedom, on the other - as a factor that led to the deconsocialization of society, gave rise to "nodal points" of tension, confrontational processes, in particular, in political and religious spheres.

The Salvage of Ideas: Schumpeter and the Core Problems Still Confronting Economics

2003 ◽  
pp. 15-26
Author(s):  
P. Wynarczyk
Keyword(s):  
The Other ◽  
The Core ◽  
Other Hand ◽  
The One

Two aspects of Schumpeter' legacy are analyzed in the article. On the one hand, he can be viewed as the custodian of the neoclassical harvest supplementing to its stock of inherited knowledge. On the other hand, the innovative character of his works is emphasized that allows to consider him a proponent of hetherodoxy. It is stressed that Schumpeter's revolutionary challenge can lead to radical changes in modern economics.

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