Relaxation time distribution from time and frequency domain dielectric spectroscopy in poly(aryl ether ether ketone)

A new application of the simulated annealing Monte Carlo procedure is presented and applied to the extraction of the relaxation time distribution from dielectric spectroscopy either in time or frequency domain. This decomposition method named simulated annealing direct signal analysis~SADSA!, is applied to computer generated curves, e(t), e8(v), and e9(v), by using the most widely accepted empirical distributions. The discretized distribution fits exactly the analytical expression which can be evaluated in these cases for the set of parameters used in the simulation. Also, both distribution functions are found to be identical which proves that the method is certainly converging to the right solution in both cases. Experimental results on amorphous poly~aryl ether ether ketone! for e(t), e8(v), and e9(v) are analyzed with SADSA and the obtained relaxation time distribution is used to go from time to frequency domain and reciprocally. The results are compared to those obtained by assuming a Havriliak–Negami profile for the distribution function. © 2000 American Institute of PhysicsConsejo Nacional de Investigaciones Científicas y Tecnológicas (CONICIT G97-000594). Comunidad de Madrid 07N/0063/1998! and to DGICYT (Grant No. PB 94-0049) Spain. FPI program of the Spanish Ministry of Science and Culture (MEC).Peer Reviewe

Étude par diffraction de rayons X et par conductibilité électrique de la mise en solution de MgF2 dans Lif

We report X-ray diffraction experiments at high température on powdered LiF single crystals doped with Mg and on mixtures of powdered LiF and MgF 2. We thus verify that the dissolution of precipitated MgF2 accounts for the steep increase of the number of carriers, as observed by electrical conductivity. The dissolution enthalpy appears to be 1.2 eV from both methods. Experiments carried out on mixtures of powdered LiF and MgF 2 confirm this value and demonstrate the high temperature solubility of MgF2 in LiF.Nous avons étudié, par diffraction de rayons X à haute température, des poudres provenant de monocristaux de LiF dopés au magnésium, ou des mélanges de poudres de LiF et de MgF2. Nous avons ainsi vérifié que l'augmentation brusque du nombre de porteurs observée en conductibilité électrique est due à la mise en solution des précipités de MgF2. L'enthalpie nécessaire à cette mise en solution est de 1,2 eV d'après les deux méthodes de mesure. Les expériences portant sur les mélanges de poudres des deux espèces cristallines ont confirmé cette valeur et ont prouvé la grande solubilité de MgF2 dans LiF à haute température

Phenolic composition changes of processed common beans: Their antioxidant and anti-inflammatory effects in intestinal cancer cells

© 2015 Elsevier Ltd. Four varieties of common beans, Negro 8025 (N), Bayo Victoria (BV), Pinto Durango (PD), and Pinto Saltillo (PS) were evaluated and compared for phenolic composition, antioxidant activity and anti-inflammatory effects by in vitro human intestinal cell model. Beans were processed by canning and boiling in open pot. Acetone/Water extracts were analyzed for phenolic composition by HPLC-PAD and HPLC-MS, screened for antioxidant activities, as lipid peroxidation inhibition and chelating capacities by inhibition of deoxi-D-ribose degradation. It was investigated their anticarcinogenic effect by inhibiting cell proliferation, decreasing interleukin-8 (IL-8), modulating interleukin-10 (IL-10), inhibiting tumor necrosis factor alpha (TNFα) and regulating nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κβ). Canning induced antioxidant compounds in order N. > PD > BV > PS associated with potential for scavenging hydroxyl radicals and metal chelating capacities. Effect of cooking on bioactive compounds was cultivar dependent, being more quantitative than qualitative due to release of bonded phenolics. Inhibition of cyclooxygenase-2 (COX-2), TNFα and NF-κβ was observed, and the induced expression of IL-10. Both effects were also cultivar and process dependent, particularly in PD beans.Peer Reviewe

Mechanisms associated to apoptosis of cancer cells by phenolic extracts from two canned common beans varieties (Phaseolus vulgaris L.)

Two varieties of common beans (Phaseolus vulgaris L.), Bayo Victoria and Negro 8025, were evaluated to determine the effect on cellular viability and mechanisms involved in apoptosis pathways, using a cellular model with HT-29 cells. Aqueous methanolic (50:50) extracts from cooked beans were analyzed for phenolic composition, identifying greater diversity of phenolic compounds in Bayo Victoria extracts. However, Negro 8025 showed greater phenolic content and cytotoxicity effects at lower media inhibitory concentrations, and greater effectiveness to activate apoptotic pathways. Proteins related to the arrest of cell cycle were modulated by both bean cultivars. Qualitative analysis by HPLC-PAD and HPLC-MS systems of phenolic compounds in common bean extracts showed mainly hydroxybenzoic and hydroxycinnamic acids, flavonols, and monomeric flavan-3-ols. Bioactive phenolics such as catechin, kaempferol, and ferulic acid were found in both cultivars as well anticancer phytochemicals such as quercetin, protocatechuic acid, myricetin, naringenin and their derivatives, and procyanidins.This work was financially supported by the Tecnológico Nacional de Mexico (TecNM) (Project grant No. 5737.16‐P). We acknowledge to the Mexican Council of Science and Technology (CONACyT) for the analytical equipment acquired by means of two project grants (No. 253333 and 224651). Author RLB also recognizes graduate scholarship from CONACyT.Peer reviewe