Authors:F. Franco, L. Pérez-Maqueda, and J. Pérez-Rodríguez
Kaolinites from well-known sources (KGa-1 and KGa-2) were used to study the influence of the particle-size reduction on the
dehydroxylation process. Size reduction of particles was obtained by ultrasound treatment to avoid the effect of the progressive
amorphization of the structure, which takes place with the traditional grinding treatment. The particle-size reduction causes
an increase of the mass loss between 140 and 390°C attributed to the loss of the hydroxyl groups exposed on the external surface
of kaolinite; a shift to lower temperatures of the endothermic effect related with the mass loss between 390 and 600°C; and
a shift of the end of dehydroxylation to lower temperatures. The first modification can be explained by an increase of the
number of hydroxyls exposed on the external surface of kaolinite which is proportional to the new surface generated in the
particle reduction process, whereas the shift of the dehydroxylation to lower temperatures is related to the reduction of
the dimensions of the particles which favour the diffusion controlled mechanisms. Comparing between the DTA curves to the
TG curves of the studied samples shows that the observed modifications in the thermal properties induced by the particle-size
reduction are greater for the low-defect kaolinite. The intensity of these modifications depends on the effectiveness of the
Authors:J. L. Pérez-Rodríguez, F. Franco, V. Ramírez-Valle, and L. A. Pérez-Maqueda
The differences on the thermal behaviour (DTG-DTA) of antigorite sample measured before and after sonication have been studied.
Sonication treatment produces negligible changes in the structure of the material but substantial textural modifications.
These modifications produce changes in the thermal behaviour of antigorite sample. Thus, it has been observed a decrease in
the dehydroxylation temperature as measured by DTG and DTA effects. For sonication treatments longer than 20 h, two new effects
of dehydroxylation are observed, the intensity of these two new effects increases with the sonication time showing a modification
in the release of structural OH. It has been also observed that the formation of forsterite takes place simultaneously with
the dehydroxylation of the antigorite. The high temperature exothermic effect is due to the recrystallization of forsterite
and not to the formation of forsterite as traditionally assumed. Modifications in the thermal dehydroxylation of antigorite
observed in this study are related to the pronounced decrease in particle size obtained by sonication.
Authors:L. Franco, R. Bravo, C. Galán, A.B. Rodríguez, C. Barriga, and Javier Cubero
Sleep deprivation affects the homeostasis of the physiological functions in the human organism. Beer is the only beverage that contains hops, a plant which has a sedative effect. Our objective is to determine the improvement of subjective sleep quality using the Pittsburgh Sleep Quality Index (PSQI). The sample was conducted among a population of 30 university students. The study took place during a period of 3 weeks, the first 7 days were used for the Control, and during the following 14 days the students ingested beer (were asked to drink non-alcoholic beer) while having dinner. The results revealed that Subjective Sleep Quality improved in the case of those students who drank one beer during dinner compared to the Control, this is corroborated by the fact that Sleep Latency decreased (p < 0.05) compared to their Control. The overall rating Global Score of Quality of Sleep also improved significantly (p < 0.05). These results confirm that the consumption of non-alcoholic beer at dinner time helps to improve the quality of sleep at night.
Authors:J. Mullens, G. Reggers, M. Ruysen, R. Carleer, J. Yperman, D. Franco, and L. Van Poucke
The oxidative degradation of HET-acid (1,4,5,6,7,7-hexachlorobicyclo [2.2.1] hept-5-en-2, 3-dicarboxylic acid) is studied
by the combination of TG, FTIR, MS and GC-MS. The gases evolved during the decomposition of this flame retardant are investigated
on-line by FTIR and by MS. Simultaneously the evolved gases are collected by an adsorbent and, after the thermal experiment,
desorbed to release the volatile products for identification using GC-MS. The combination of these techniques offers the unambiguous
identification of the evolved products as a function of temperature. The main identified products are CO2, H2O, Cl2, HCl, C2Cl4, maleic acid anhydride, HET-acid anhydride, chlorinated cyclic hydrocarbons and chlorinated unsaturated linear hydrocarbons.
Authors:A. Manich, J. Carilla, R. Miguel, J. Lucas, F. Franco, L. Montero, and D. Cayuela
A partially oriented melt-extruded PLA multifilament was false-twist textured to stabilize its structure. Conventional DSC
analysis showed a relaxation peak at the end of glass transition. Simultaneous consideration of the TMA curve enabled us to
evaluate both the relaxation and the cold crystallisation produced during the DSC scan. The periodic load applied during TMA
experiments also enabled us to examine the evolution of Young’s modulus along the glass transition, relaxation and cold crystallisation
phenomena. Increases in Young’s modulus and in enthalpy are related because of crystallisation. Texturing increased crystallinity
and decreased cold crystallisation of PLA during the DSC scan.
Authors:J. Mullens, A. Vos, A. De Backer, D. Franco, J. Yperman, and L. Van Poucke
The 124 superconductor YBa2Cu4O8 was prepared from the oxalate precursor Y2(C2O4)3. ·4BaC2O4·8CuC2O4·xH2O at one atmosphere oxygen pressure. In O2 the precursor decomposes in one step at 300°C and more gradually (300°–600°C) in Ar. The stability of the superconductor
is strongly dependent on the gas atmosphere: in O2 and in air there is no significant weight change as long as the temperature does not exceed 800°C, whereas in a 1% O2-99%N2 mixture decomposition starts at about 670°C with the formation of CuO and YBa2Cu3Ox withx<7. The reduction of YBa2Cu4O8 in a 5% H2-95% Ar mixture takes place in at least four major steps with formation of products such as Y2O3, BaO, Cu2O, Cu, BaY2O4 and Ba4Y2O7.
Authors:L. Franco, C. Sánchez, R. Bravo, A. Rodriguez, C. Barriga, and Javier Juánez
The hop (Humulus lupulus), a component of beer, is a sedative plant whose pharmacological activity is due principally to its bitter resins, especially to the α-acid component 2-methyl-3-buten-2-ol. The mechanism of action of the resin of hop consists of increasing the activity of the neurotransmitter γ-aminobutyric (GABA), inhibiting the central nervous system (CNS). Objectives: To analyze in an experimental model of diurnal animal the sedative effect of hop, a component of beer, on the activity/rest rhythm. Methods: Experiments were performed with common quail (Coturnix coturnix) similar to humans in the sleep-wake rhythm, isolated in 25 × 25 × 25 cm methacrylate cages, with food and water ad libitum, in a room with artificial ventilation (22 ± 1 °C) and a lighting cycle of 12L/12D (n = 5). The doses administered, close to the content of non-alcoholic beer, were 1, 2 and 11 mg extract of hop as one capsule per day, at 18:00 h for one week. A control group received capsules only with a methylcellulose excipient and a basal group received no treatment. The chronobiological analysis of the animals’ activity captured and logged by the software DAS24 was performed using the Ritme computer program (cosinor methods). Results: With the dose of 2 mg, there was a statistically significant (p < 0.05) reduction of the arithmetic mean nocturnal activity (23 ± 3.0) with respect to the basal (38.56 ± 2.79), control (38.1 ± 2.8) and other doses groups 1 mg (52.04 ± 3.65) and 11 mg (47.47 ± 5.88). This dose of 2 mg, similar to the concentration in beer, was more effective in reducing nocturnal activity than the other doses of 1 and 11 mg, as well as preserving the circadian activity/rest rhythm. Conclusion: The concentration of 2 mg of hop extract effectively decreased nocturnal activity in the circadian activity rhythm. On the basis of this investigation, administration of non-alcoholic beer would be recommended due to its hop content and consequent sedative action, which would be an aid to nocturnal sleep.
Authors:Nouga C. Batista, José L. Silva Sá, Bruce R. McGarvey, Douglas W. Franco, and Benedito S. Lima-Neto
The presence of paramagnetic species in the aqueous ring opening metathesis polymerizations of the exo,exo-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid monomer with RuCl3 and K2[RuCl5H2O] compounds was studied using ESR techniques. It was observed that the intensities of the RuIII signals in the ESR spectra decrease on the time scale of the induction period so that the ROMP can take place. The intensity of the RuIII signal almost disappeared 50 min after reacting with K2[RuCl5H2O] and after 100 min in the case of RuCl3. Reactions of the cis-[Ru(NH3)4(H2O)2](tfms)3 and [Ru(NH3)5H2O](tfms)3 complexes with the monomer and different organic compounds representing the organic functions in the monomer (furan, norbornene, but-2-ene-1,4-diol and formic, acetic, oxalic and maleic acids) were also monitored by ESR and UV/vis spectra. It was deduced that the organic acids provide the disappearance of the RuIII signal. The proton NMR relaxation times of the residual water in D2O for reactions with oxalic acid suggested that the presence of paramagnetic ions in the solution decreases along with the disappearance of the ESR signal for RuIII. It was suggested that diamagnetic Ru species were indeed produced in the medium.
Authors:R Bravo Santos, J Delgado, J Cubero, L Franco, S Ruiz-Moyano, M Mesa, AB Rodríguez, C Uguz, and C Barriga
The objective of the present study was to compare differences between elderly rats and young obesity-induced rats in their activity/inactivity circadian rhythm. The investigation was motivated by the differences reported previously for the circadian rhythms of both obese and elderly humans (and other animals), and those of healthy, young or mature individuals. Three groups of rats were formed: a young control group which was fed a standard chow for rodents; a young obesity-induced group which was fed a high-fat diet for four months; and an elderly control group with rats aged 2.5 years that was fed a standard chow for rodents. Activity/inactivity data were registered through actimetry using infrared actimeter systems in each cage to detect activity. Data were logged on a computer and chronobiological analysis were performed. The results showed diurnal activity (sleep time), nocturnal activity (awake time), amplitude, acrophase, and interdaily stability to be similar between the young obesity-induced group and the elderly control group, but different in the young control group. We have concluded that obesity leads to a chronodisruption status in the body similar to the circadian rhythm degradation observed in the elderly.