Miguel Hernandez

A fossil stemmiulid millipede (Diplopoda: Stemmiulida) from the Miocene amber of Simojovel, Chiapas, México

A fossil millipede representative of the order Stemmiulida is described on the basis of a well-preserved adult female trapped in amber from the Miocene of Simojovel, Chiapas, south-eastern México. The fossil specimen is named as Parastemmiulus elektron, a new genus and species. As observed in extant stemmiulids, this fossil shows a reduced number of ocelli, the distal larger than the proximal, as well as a total of 46 trunk segments including 2 apodous segments in front of the telson. The head of this ancient stemmiulid has three ocelli and a Tömösváry organ, characteristics not reported before in Stemmiulida, requiring the diagnosis of the order to be emended.http://zoobank.org/urn:lsid:zoobank.org:pub:361400A8-37D4-421F-B4FD-A0AE63BE538C

Corrosion Resistance of AA2024-T3 Coated with Graphene/Sol-Gel Films

Graphene is a two-dimensional network of carbon atoms with optimal thermal, electronic and chemical stability properties that promise different and versatile applications in various fields including the protection of metals from corrosion phenomena. For this reason in this paper graphene was employed and studied as an agent dopand incorporated into hybrid sol-gel coatings to enhance their resistance in saline media and to improve the durability of these films. Graphene was obtained by using an electrochemical method involving oxidation and reduction reactions in a sodium lauryl sulfate solution. On the other hand, the hybrid sol-gel was synthesized from the combination of inorganic and organic precursors, zirconium (IV) n-propoxide (TPOZ) and 3-glycidoxipropiltrimetoxysilane (GLYMO) respectively. In order to obtain the coating system (graphene/sol-gel) two different procedures were applied onto clean aluminum plates: a) the electrodeposition of graphene and b) the graphene-doped sol-gel coating. Differential scanning calorimetry, scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the results, which demonstrate an improvement of the corrosion properties of the films with the incorporation of graphene compounds.

Electroconvulsive shock decreases excitatory responses to serotonin in the caudate nucleus of the rat

1. The present study explored the changes on the firing rate of caudate neurons, and the response to serotonin locally applied in rats submitted to electroconvulsive shock. 2. Electroconvulsive shock diminished the firing rate of caudate neurons and blocked the excitatory response produced by serotonin in a small amount of serotonin-sensitive neurons. 3. Results are likely to be related with transient changes in the receptors affinity and dissociation constants, which may impinge on immediate memory retrieval.

Corrosion Behavior of Hybrid Sol-Gel Films Reinforced with Electrospun Nanofibers

The aim of this paper is to evaluate the efficiency of hybrid sol-gel coatings reinforced with electrospinning nanofibers doped with cerium nitrate and ceria particles to increase the corrosion properties of the coating. Poly(vinyl alcohol) solutions doped with cerium nitrate and ceria were electrospun onto clean commercial aluminum alloy AA2024-T3 plates and then coated with a hybrid sol-gel system using the dip-coating procedure. The hybrid materials synthesized via sol-gel chemistry were prepared from inorganic-organic precursors: zirconium (IV) propoxide and 3-glycidoxypropyltrimetoxysilane. The electrochemical impedance spectroscopy technique was applied to evaluate the electrochemical properties of the film whereas scanning electron microscopy and atomic force microscopy were employed to characterize the surface characteristics. The incorporation of nanofibers into the sol-gel system provides good barrier properties that increase the corrosion resistance of the aluminum at longer exposure times in saline media. This protection depends of the type of inhibitor loaded within the electrospun nanofibers.