Hydrogen Production by Methanol Steam Reforming Over Pd/ZrO2�CTiO2 Catalysts

Pd/ZrO₂?CTiO₂ catalysts were synthesized by sol?Cgel method and studied on the steam reforming of methanol reaction for hydrogen production. X-ray diffraction patterns of the Pd supported on single oxides showed crystalline structures associated with the zirconia or titania respectively. However, the XRD pattern of the mixed ZrO₂?CTiO₂ oxide showed broad diffraction pattern consistent with an amorphous material. The reducibility of the PdO supported on single and mixed oxides showed a negative peak associated with the desorption of H₂ due to the decomposition of Pd-hydride (PdH); as well as, positive peaks related with the hydrogen consumption on the reduction of the PdO supported. Catalytic activity on the palladium supported on the mixed ZrO₂?CTiO₂ oxide showed higher catalytic activity than the Pd supported on the single TiO₂ or ZrO₂ oxides. This finding was associated at the higher Pd species present in the Pd/ZrO₂?CTiO₂ than on the Pd/ZrO₂ or Pd/TiO₂ catalysts how was observed by TPR.     

Trehalose Metabolism: From Osmoprotection to Signaling

Trehalose is a non-reducing disaccharide formed by two glucose molecules. It is widely distributed in Nature and has been isolated from certain species of bacteria, fungi, invertebrates and plants, which are capable of surviving in a dehydrated state for months or years and subsequently being revived after a few hours of being in contact with water. This disaccharide has many biotechnological applications, as its physicochemical properties allow it to be used to preserve foods, enzymes, vaccines, cells etc., in a dehydrated state at room temperature. One of the most striking findings a decade ago was the discovery of the genes involved in trehalose biosynthesis, present in a great number of organisms that do not accumulate trehalose to significant levels. In plants, this disaccharide has diverse functions and plays an essential role in various stages of development, for example in the formation of the embryo and in flowering. Trehalose also appears to be involved in the regulation of carbon metabolism and photosynthesis. Recently it has been discovered that this sugar plays an important role in plant-microorganism interactions.     

RNA Relics and Origin of Life

A number of small RNA sequences, located in different non-coding sequences and highly preserved across the tree of life, have been suggested to be molecular fossils, of ancient (and possibly primordial) origin. On the other hand, recent years have revealed the existence of ubiquitous roles for small RNA sequences in modern organisms, in functions ranging from cell regulation to antiviral activity. We propose that a single thread can be followed from the beginning of life in RNA structures selected only for stability reasons through the RNA relics and up to the current coevolution of RNA sequences; such an understanding would shed light both on the history and on the present development of the RNA machinery and interactions. After presenting the evidence (by comparing their sequences) that points toward a common thread, we discuss a scenario of genome coevolution (with emphasis on viral infectious processes) and finally propose a plan for the reevaluation of the stereochemical theory of the genetic code; we claim that it may still be relevant, and not only for understanding the origin of life, but also for a comprehensive picture of regulation in present-day cells.     

Corrosion behavior of Eurofer 97 and ODS-Eurofer alloys compared to traditional stainless steels

In the present work, the corrosion resistance of ferritic-martensitic EUROFER 97 and ODS-EUROFER steels was tested in solutions containing NaCl or H₂SO₄ and KSCN, both at 25 °C. The results were compared to those of AISI 430 ferritic and AISI 410 martensitic conventional stainless steels. The as-received samples were tested by electrochemical techniques, specifically, electrochemical impedance spectroscopy, potentiodynamic polarization curves, and double-loop electrochemical potentiokinetic reactivation tests. The surfaces were observed by scanning electron microscopy after exposure to corrosive media. The results showed that EUROFER 97 and ODS-EUROFER alloys present similar corrosion resistance but lower than ferritic AISI 430 and martensitic 410 stainless steels.