Synthesis and characterization of highly dispersed bimetallic Au-Rh nanoparticles supported on titanate nanotubes for CO oxidation reaction at low temperature

Low-temperature CO oxidation was carried out by using rhodium incorporated into titanate nanotubes (Rh/NTs) prepared by the sol-gel and hydrothermal methods; otherwise, gold nanoparticles were deposited homogeneously onto the Rh/NT surface through the deposition-precipitation with urea (DPU) method. The Au-Rh/NT sample exhibited high metal dispersion (55%), outstanding CO oxidation at low temperature, and better resistance to deactivation than the monometallic Rh/NT and Au/NT samples. The characterization of bimetallic samples, with particle sizes from 1 to 3 nm, revealed the remarkable presence of interacting Au and Rh species in metallic state. In this way, Au⁰ and Rh⁰ were answerable for the higher catalytic activity observed in the bimetallic samples. The interaction between Au and Rh in the nanoparticles of Au-Rh/NT promoted a synergistic effect on the CO oxidation reaction, explained by the creation of new CO adsorption sites.

Spectroscopic and Mechanical Studies on the Fe-based Amorphous Alloy 2605SA1

The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the microhardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by PALS and MS, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem.    

Stress and corticosterone increase the readily releasable pool of glutamate vesicles in synaptic terminals of prefrontal and frontal cortex

Stress and glucocorticoids alter glutamatergic transmission, and the outcome of stress may range from plasticity enhancing effects to noxious, maladaptive changes. We have previously demonstrated that acute stress rapidly increases glutamate release in prefrontal and frontal cortex via glucocorticoid receptor and accumulation of presynaptic SNARE complex. Here we compared the ex vivo effects of acute stress on glutamate release with those of in vitro application of corticosterone, to analyze whether acute effect of stress on glutamatergic transmission is mediated by local synaptic action of corticosterone. We found that acute stress increases both the readily releasable pool (RRP) of vesicles and depolarization-evoked glutamate release, while application in vitro of corticosterone rapidly increases the RRP, an effect dependent on synaptic receptors for the hormone, but does not induce glutamate release for up to 20 min. These findings indicate that corticosterone mediates the enhancement of glutamate release induced by acute stress, and the rapid non-genomic action of the hormone is necessary but not sufficient for this effect.

Structural and spectroscopic characterization of ZrO2:Eu3+ nanoparticles

ZrO2:Eu3+ nanocrystals were prepared by the sol-gel technique. The structural and luminescence properties of europium doped zirconia with 0.5 to 2 mol% were studied by Mössbauer spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and photoluminescence (PL) under UV excitation. Structural characterization shows a crystallite size between 16 to 55 nm and monoclinic and tetragonal zirconia phases as the main crystalline structure. XRD patterns shown that the content of the active ions stabilizes the tetragonal structure of ZrO2 at 1000 degrees C, being 100% for 2 mol% Eu2O3 doped sample. Such results are in agreement with HRTEM and Raman spectroscopy. The Mössbauer spectra of the ZrO2:Eu3+ samples show a single peak near zero velocity which is attributed to Eu+3. Luminescence characterization shows the typical emission band centered at 595 and 611 nm. Change in the structure of such band was observed and explained in terms of crystalline phase change. The dependence between the fluorescence emission and the crystalline structure is discussed.

[Nursing of intubation]

Recent developments in noninvasive ventilation allow the intensivists to delay the time o intubation of the patient admitted to the ICU. This new possibility of a gain in time leads to the fact that those patients who are intubated in the ICLI, are patients with a very compromised hemodynamic and respiratory situation. For this reason, we developed a specific protocol regarding the intubation procedure of this kind of patients. This paper reviews our strategies for endotracheal tube positioning in critically ill patients and shows the fundamental role of the nurses during this procedure.

[Nursing of tracheostomy]

In this abstract we have analyzed the different techniques of tracheostomy, considering new semplified methods of this procedure and therefore the common use of it in weaning from mechanical ventilation the critical care patients. We've tried to summarize guide lines of the preoperative, operative and postoperative procedures of tracheostomy, comparing our nursing clinical experience in ICU and the latest literature. We've primarily analyzed the nursing aspects of this issue, trying to focus on the priority of the treatment of the tracheostomezed patient.

Sulfation of nod factors via nodHPQ is nodD independent in Rhizobium tropici CIAT899

A cosmid from the Rhizobium tropici CIAT899 symbiotic plasmid, containing most of the nodulation genes described in this strain, has been isolated. Although this cosmid does not carry a nodD gene, it confers ability to heterologous Rhizobium spp. to nodulate R. tropici hosts (Phaseolus vulgaris, Macroptilium atropurpureum, and Leucaena leucocephala). The observed phenotype is due to constitutive expression of the nodABCSUIJ operon, which has lost its regulatory region and is expressed from a promoter present in the cloning vector. Thin-layer chromatography (TLC) analysis of the Nod factors produced by this construction shows that it is still capable of synthesizing sulfated compounds, suggesting that the nodHPQ genes are organized as an operon that is transcribed in a nodD-independent manner and is not regulated by flavonoids.

Nucleotide sequence of the Rhizobium etli nodS gene

The complete nucleotide sequence of the nodS gene from the bean-nodulating Rhizobium etli, presumably encoding a methyltransferase, was determined. A phylogenetic analysis of five different NodS proteins from three genera of Gram- soil bacteria, Azorhizobium, Bradyrhizobium and Rhizobium, was performed.

A Rhizobium tropici DNA region carrying the amino-terminal half of a nodD gene and a nod-box-like sequence confers host-range extension

Rhizobium tropici CIAT899 is a broad-host-range strain that, in addition to Phaseolus, nodulates other plant legumes such as Leucaena and Macroptilium. The narrow-host-range of Rhizobium leguminosarum biovars phaseoli (strain CE3) and trifolii (strain RS1051) can be extended to Leucaena esculenta and Phaseolus vulgaris plants, respectively, by the introduction of a DNA fragment 521 bp long, which carries 128 amino acids of the amino-terminal region of a nodD gene from R. tropici, as well as a putative nod-box-like sequence, divergently oriented. The 521 bp fragment, in the presence of L. esculenta or P. vulgaris root exudates, induced a R. leguminosarum bv. viciae nodA-lacZ fusion in either a CE3 or RS1051 background, respectively.