Search results for "Constants"

Protein Adsorption Hysteresis and Transient States of Fibrinogen and BMP-2 as Model Mechanisms for Proteome-Binding to Implants

2020

Abstract Protein adsorption studies returned to the focus of medical therapeutics, when it was found that up to 2500 non-plasma proteins adsorbed to hip implants during arthroplastic surgery, challenging peri-implant healing models. Questions have re-emerged as to the implications of uncontrolled protein unfolding after adsorption. In past studies on the cooperativity of protein binding we discovered protein adsorption hysteresis, a thermodynamically irreversible process. The present precursory study comprises real-time kinetic (TIRF-Rheometry) and equilibrium (125I-tracer ) studies on the hysteretic binding of fibrinogen and rhBMP-2 to titanium and glass surfaces via transient states. Ther…

Determination of basic strenght of aliphatic amines through ion pair formation in some ionic liquid solutions

2010

To have an evaluation of the basic strength of aliphatic amines in ionic liquid solution, the stability constants relevant to the formation of amine/p-nitrophenol ion pairs were determined in different ionic liquids at 298 K. In particular, aliphatic (pyrrolidinium) and aromatic (imidazolium) ionic liquids were used. Imidazolium ions, bmim(+) and bm(2)im(+), having different hydrogen bond donor abilities were taken into account. Anions were chosen ([BF(4)(-)], [PF(6)(-)], and [NTf(2)(-)]; where NTf(2) = bis(trifluoromethansulfonyl)imide) showing different shape, size, and coordination ability. Several primary, secondary (cyclic or not), and tertiary amines were used to study the effect of a…

Calculation of magnetic coupling constants with hybrid density functionals

2013

The currently available computational methods for the calculation of magnetic coupling constants with density functional theory have been reviewed. These methods include modern approximations to the exchangecorrelation functional, such as hybrid, range-separated and double-hybrid functionals, as well as approaches to treat the severe spin symmetry problems encountered in density functional calculations of magnetic interactions. In addition to the commonly used unrestricted Kohn–Sham formalism, density functional methods based on multireference wave functions and ensemble densities are also discussed. Performance of these models based on various studies has been summarized. The results indic…

Lyapunov quantities and limit cycles in two-dimensional dynamical systems : analytical methods, symbolic computation and visualization

2011

Interaction of methyltin(IV) compounds with carboxylate ligands. Part 1: formation and stability of methyltin(IV)–carboxylate complexes and their rel…

2006

Quantitative data on the stability of mono-, di- and trimethyltin(IV)-carboxylate complexes (acetate, malonate, succinate, malate, oxydiacetate, diethylenetrioxydiacetate, tricarballylate, citrate, butanetetracarboxylate and mellitate) are reported at t=25°C and I → 0 mol l - 1 . Several mononuclear, mixed proton, mixed hydroxo and polynuclear species are formed in these systems. As expected, the stability trend is mono- > di- > trimethyltin(IV) and mono < di < tri < tetra < hexa for the organotin moieties and carboxylate ligands investigated, respectively. Moreover, ligands containing, in addition to carboxylic,-O-and-OH groups show a significantly higher stability with respect to analogou…

Speciation of organotin compounds in NaCl aqueous solution. Interaction of mono-, di- and triorganotin(IV) cations with nucleotides 5’ monophosphates

2004

Formation constants for complex species of mono-, di- and tri-alkyltin(IV) cations with somenucleotide 5-monophosphates (AMP, UMP, IMP and GMP) are reported, atT=25◦CandatI=0.16 mol l−1(NaCl). The investigation was performed in the light of speciation of organometalliccompounds in natural fluids in the presence of nucleotides whose biological importance is wellrecognized. The simple and mixed hydrolytic complex species formed in all the systems investigatedin the pH range 3–9 are (L=nucleotide; M=organotin cation RxSn(4−x)+, withx=1to3):ML+,ML(OH)0and ML(OH)2−for the system CH3Sn3+–L (L=AMP, IMP, UMP); ML0and ML(OH)−for the system (C2H5)2Sn2+–L (L=AMP, IMP, UMP); ML−, ML(OH)2−,MLH0and M2L(O…

Definición y unidades de las constantes de equilibrio en los libros de texto de Química general preuniversitarios y universitarios

2021

En este trabajo, una vez definidas las constantes de equilibrio experimentales, Kp y Kc, así como la constante de equilibrio termodinámica, Kº, se analiza su incorrecto tratamiento por parte de libros de texto de química general. Se expone la forma en que libros de química general de universidad y de bachillerato manejan las unidades de las constantes de equilibrio. Muchos textos no expresan con unidades los valores de Kp y Kc calculados. Además, en la mayoría de los casos, Kº no se define, y como resultado existe una confusión muy extendida acerca de estos conceptos. Este problema terminológico ocasiona que en muchos libros se confunda Kp con Kº. Se propone que la definición correcta de la…

A Theoretical and Experimental Investigation of the Spectroscopic Properties of a DNA-Intercalator Salphen-Type ZnIIComplex

2014

The photophysical and DNA-binding properties of the cationic zinc(II) complex of 5-triethylammonium methyl salicylidene ortho-phenylenediiminato (ZnL 2 + ) were investi- gated by a combination of experimental and theoretical methods. DFT calculations were performed on both the ground and the first excited states of ZnL 2 + and on its possi- ble mono- and dioxidation products, both in vacuo and in selected solvents mimicked by the polarizable continuum model. Comparison of the calculated absorption and fluores- cence transitions with the corresponding experimental data led to the conclusion that visible light induces a two-elec- tron photooxidation process located on the phenylenediimi- nato…

K°- K°, - D° and B° - B° oscillations in the Standard Model and beyond from unquenched Twisted Mass Lattice QCD

2013

El análisis del triángulo de unitariedad y la búsqueda de cotas restrictivas sobre las escala de nueva física requiere medidas precisas de las amplitudes de mezcla de las oscilaciones de mesones. El retículo proporciona una óptima herramienta no perturbativa para el cálculo de dichos elementos de matriz con incertidumbres del 1% y errores sistemáticos bajo control. La tesis se centra en el cálculo de los parámetros B, que controlan las oscilaciones de mesones, la masa del quark b y las constantes de desintegración fB y fBs a partir de QCD simulada en el retículo con fermiones Twisted Mass e incluyendo los efectos cuánticos de quarks dinámicos en el mar. A lo largo de esta tesis, a partir de…

Ground and first excited electronic state interaction of FAD with some β-carboline derivatives

1987

Abstract The spectrophotometric and thermodynamic properties of molecular complexes of flavine adenine dinucleotide (FAD) with some dihydro β-carboline derivatives have been investigated in aqueous solution. The molecular associations have been examined by means of electronic absorption spectra, since in each a new charge-transfer band has been located, and also the variation of the fluorescence emission of FAD on the solutions has been observed. The formation constants for the molecular complexes were determined from absorption data, using the Foster-Hammick-Wardley method. The quenching fluorescence phenomena observed in FAD is related to the concentration of the dihydro β-carboline deriv…