A kinetic study of the reactions of sulfate and dihydrogen phosphate radicals with epicatechin,epicatechingallate, and epigalocatechingallate

The bimolecular rate constants for the reactions of sulfate radicals with epicatechin (EC), epicatechingallate (ECG), and epigallocatechingallate (EGCG) were found to be (1.46 ± 0.06) × 10⁹, (1.20 ± 0.08) × 10⁹, and (1.04 ± 0.07) × 10⁹, respectively. The activation energy [E_A = 9 ± 3 kJ mol^?1] and preexponential factor [A = (4.8 ± 0.6) × 10¹⁰] for the reaction of EC with the sulfate radical were measured in the temperature range 288–303 K. The phenoxyl radicals of EC (λ_max = 310 nm) were obtained both by the reaction of this flavonoid with the sulfate radicals and by photoionization. The measured bimolecular rate constants for the reactions of the dihydrogen phosphate radicals with EC, ECG, and EGCG were (7.8 ± 0.9) × 10⁸, (8.5 ± 0.4) × 10⁸, and (6.8 ± 0.4) × 10⁸, respectively. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 391–396, 2010     

A kinetic study of the aqueous phase oxidation of di-μ-oxo-bis(L-cysteine)-oxomolybdenum(V) by molecular oxygen

The molecular oxygen-mediated decomposition of the binuclear complex, prepared from oxomolybdate(V) and L-(+)-cysteine, was studied spectrophotometrically at pH 3.5–5.6. The formation of MoVI was detected. The effects of pH and [O2] on the decomposition kinetics are given by the equation:

Trusting the messenger because of the message: feedback dynamics from information quality to source evaluation

Information provided by a source should be assessed by an intelligent agent on the basis of several criteria: most notably, its content and the trust one has in its source. In turn, the observed quality of information should feed back on the assessment of its source, and such feedback should intelligently distribute among different features of the source—e.g., competence and sincerity. We propose a formal framework in which trust is treated as a multi-dimensional concept relativized to the sincerity of the source and its competence with respect to specific domains: both these aspects influence the assessment of the information, and also determine a feedback on the trustworthiness degree of its source. We provide a framework to describe the combined effects of competence and sincerity on the perceived quality of information. We focus on the feedback dynamics from information quality to source evaluation, highlighting the role that uncertainty reduction and social comparison play in determining the amount and the distribution of feedback.     

The matter‐antimatter interpretation of Kerr spacetime

Repulsive gravity is not very popular in physics. However, one comes across it in at least two main occurrences in general relativity: in the negative‐r region of Kerr spacetime, and as the result of the gravitational interaction between matter and antimatter, when the latter is assumed to be CPT‐transformed matter. Here we show how these two independent developments of general relativity are perfectly consistent in predicting gravitational repulsion and how the above Kerr negative‐r region can be interpreted as the habitat of antimatter. As a consequence, matter particles traveling along vortical geodesics can pass through the throat of a rotating black hole and emerge as antimatter particles (and vice versa). An experimental definitive answer on the gravitational behavior of antimatter is awaited in the next few years.

     

A socio-cognitive model of trust using argumentation theory

Trust is used to minimise the uncertainty in the interactions of the agents especially in case of conflicting information from different sources. Besides conflicts among information there can also be conflicts about the trust attributed to the information sources. In this paper, we discuss how to reason about trust using argumentation theory, so to express also the possibly conflicting motivations about trust and distrust. The methodology of meta-argumentation allows us to model both information and information sources as arguments and to argue about them. First, we present a model for representing evidence provided as motivation of the sources’ arguments to represent the need of a trusted source to believe the information, and we show how to model the information sources in a way that it can be argued whether they should be considered trustworthy or not. Second, we provide a focused representation of trust about the sources in which trust concerns not only the sources but also the information items and the relation with other information. Third, we introduce the feedback on the trustworthiness of the sources and the information items they propose, such that an attack to the trustworthiness of the items feeds back on the trustworthiness of the source. Finally, we distinguish two dimensions of trust, namely competence and sincerity, and we present a formal way to express those dimensions, only informally described in the socio-cognitive models of trust.