Computational Antioxidant Capacity Simulation (CAOCS): A Novel Framework of Antioxidant Capacity Profiling

Inconsistent ranking is a well-known drawback of antioxidant capacity (AOC) profiling methodologies that use free-radical species as oxidant. This problem leads to assay results that are not biorelevant. Linear free energy relationships (LFER) theory predicts proton transfer (PT) kinetics as a surrogate for biorelevant hydrogen atom transfer (HAT) kinetics. Computational antioxidant capacity simulation (CAOCS), based on real-time proton transfer kinetics modeling (PTKM) of polyphenols and phenol-like small molecules, inspired a novel AOC profiling methodology. Kinetic data acquired by incremental addition of resorcinol to an oxidized probe (phenol red), was fitted to mono-exponential decay equation (MED). Absorbance decay data from strongly antioxidant phenol-like molecules (e.g. ascorbic acid) and a new chromogenic probe (phenolphthalein) was fitted to MED and bi-exponential decay equation. The preferred model and corresponding best-fit rate constant (Kptt) was identified by comparison of fits, using Akaike’s Information Criterion (AICc). Photometric phenolphthalein assay (PPA)-derived metric was normalized with photometric phenol red assay (PPRA) results by using a function developed from proton concentration differential between phenolphthalein and phenol red, with respect to decay threshold to plateau (assay endpoint) interval. pKa dependence of the CAOCS’ metric is a signature of structure–function relationships, and hence, biorelevance. It is shown, unambiguously, that a combination of two phenolic probe molecules, an analytical system devoid of free radicals, and statistical identification of preferred exponential decay fit to PT kinetics data, constitutes a novel algorithm for AOC profiling of polyphenols and phenol-like molecules. This methodology holds a promise of utility in quality assurance of dietary supplements.

Structural Solutions for Ship Hull Plates Strengthening, under Blast Loads

The paper presents selected results of a study concerning the protective capacity of ship hull plates, made out of layered composite plates. A scenario to evaluate the behaviour of the ship structure plate under blast loading is presented. The nonlinear analysis on a 3-D FEM model by using composite elements was performed. The methodology for the blast pressure charging and the mechanism of the blast wave in free air are given. The space pressure variation is determined by using Friedlander exponential decay equation. According to the methods used in this paper an individual pressure-time history to each element based on its distance from the blast is assigned. The dynamic response of the composite plate is shown.

Analysis of the Disappearance Curve of Labelled Fibrinogen at the Time of Hyperfibrinogenemia in Rabbits with Acute or Chronic Intravascular Coagulation

SummaryIn order to study fibrinogen metabolism, the disappearance curve of 125I-labelled homologous fibrinogen was investigated in the rabbits with experimentally induced acute or chronic intravascular coagulation by injection of Lycopodium spores or thromboplastin. The results obtained were as follows.1. Using haemolysate, an intermediate phase with upward convexity was clearly recognized between the early rapid-decay phase and the late slow phase in each radioactivity decay curve obtained in groups of rabbits. This convexity was most marked with acute intravascular coagulation induced by injection of Lycopodium spores, and was less marked, although higher, with chronic intravascular coagulation induced by injection of thromboplastin than that in the normal control.2. The disappearance curve with the intermediate phase could be expressed, in approximation, as a sum of 2 equations - the initial exponential decay equation and the late parabolic one.3. From the results obtained by separate examinations of the disappearance curve of plasma, fibrin clots and serum in rabbits with acute intravascular coagulation induced by injection of Lycopodium spores, the intermediate phase appears to be influenced more by the secondary increase of labelled non-clottable part than recirculation of the labelled fibrinogen.4. The half time (27.4 hours) of the radioactivity in fibrin clots at the late phase observed in the group of rabbits with acute intravascular coagulation induced by injection of Lycopodium spores was shorter than that in the normal rabbits (50.2 hours). This fact may indicate that the increase of fibrinogen in the group of rabbits with acute intravascular coagulation induced by the injection of Lycopodium spores is due to overproduction of fibrinogen.5. The half time of labelled fibrinogen should be calculated from disappearance curve of fibrin clots, instead from that of haemolysate or plasma.