In situ surface characterization and oxygen reduction reaction on shape-controlled gold nanoparticles

Gold nanoparticles of different shapes/surface structures were synthesized and electrochemically characterized. An in-situ surface characterization of the Au nanoparticles, which was able to obtain qualitative information about the type and relative sizes of the different facets present in the surface of the Au nanoparticles, was carried out by using Pb Under Potential Deposition (UPD) in alkaline solutions as a surface sensitive tool. The results obtained show that the final atomic arrangement on the surface can be different from that expected from the bulk structure of the well-defined shape Au nanoparticles. In this way, the development of precise in-situ methods to measure the distribution of the different sites on the nanoparticle surface, as lead UPD on gold surfaces, is highlighted. Oxygen Reduction Reaction (ORR) was performed on the different Au nanoparticles. In agreement with the particular sensitivity of the oxygen reduction to the presence of Au(100) surface domains, cubic Au nanoparticles show much better electrocatalytic activity for ORR than small spherical particles and long nanorods, in agreement with the presence of a great fraction of (100) terrace sites on the surface of cubic gold nanoparticles.

[Epidural anesthesia for coronary revascularization in the conscious patient]

Thoracic epidural anesthesia has been widely used to complement general anesthesia in coronary artery bypass grafting. The main advantages of the combination are excellent pain control and a less pronounced stress response to surgery. The invasiveness of surgery to treat ischemic heart disease has been attenuated thanks to the use of the mini-sternotomy and coronary anastomosis without extracorporeal circulation. In 4 patients, coronary artery revascularization was carried out via a mini-sternotomy, grafting the anterior descending artery to the left internal thoracic artery under high thoracic epidural anesthesia (block of segments T1-T8) with a perfusion of 0.75% ropivacaine and fentanyl in a conscious patient. There were no hemodynamic or respiratory complications during surgery. The mean duration of stay in the intensive care unit was less than 18 hours and the mean hospital stay was less than 5 days. Postoperative coronary arteriograms demonstrated the patency of all grafts and all patients were asymptomatic at 1 month. Our initial experience suggests that the use of only high thoracic epidural anesthesia is feasible in coronary revascularization in selected, cooperative patients who require a single coronary bypass graft.

Monothiol glutaredoxins: a common domain for multiple functions

Monothiol glutaredoxins with the CGFS sequence at the active site are widespread among prokaryotes and eukaryotes. Two subclasses exist, those with a single glutaredoxin domain and those with a thioredoxin-like region followed by one or more glutaredoxin domains. Studies in Saccharomyces cerevisiae have demonstrated the role of the Grx5 protein in the biogenesis of iron-sulfur clusters. Grx5 homologues in other eukaryotes could carry out similar functions. Two S. cerevisiae monothiol glutaredoxins with the thioredoxin-like extension, Grx3 and Grx4, are modulators of the transcriptional activator Aft1, which regulates iron uptake in yeast. The human PICOT protein is a Grx3/Grx4 homologue with the same hybrid primary structure that regulates protein kinase C activity and may participate in physiological processes such as control of cardiac function. Therefore, monothiol glutaredoxins share a common basic structural motif and biochemical mechanism of action, while participating in a diversity of cellular functions as protein redox regulators.

Tellurium adatoms as an in-situ surface probe of (111) two-dimensional domains at platinum surfaces

Irreversibly adsorbed tellurium has been studied as a probe to quantify ordered domains in platinum electrodes. The surface redox process of adsorbed tellurium on the Pt(111) electrode and Pt(111) stepped surfaces takes place around 0.85 V in a well-defined peak. The behavior of this redox process on the Pt(111) vicinal surfaces indicates that the tellurium atoms involved in the redox process are only those deposited on the (111) terrace sites. Moreover, the corresponding charge density is proportional to the number of sites on (111) ordered domains (terraces) that are, at least, three atoms wide. Hence, this charge density can be used to measure the number of (111) terrace sites on any given platinum sample. Structural information about tellurium adsorption is obtained from atomic-resolution STM images for the Pt(111) and Pt(10, 10, 9) electrodes. A rectangular structure (2 x radical 3) and a compact hexagonal structure (11 x 8) were identified. However, the redox peak for adsorbed tellurium on (100) domains at 1.03 V overlaps with peaks arising from steps and (110) sites. Therefore, it cannot be used without problems for the determination of (100) sites on a platinum sample. On the (100) terraces, the surface structure of the adsorbed tellurium is c(2 x 2), as revealed by STM. Finally, tellurium irreversible adsorption has been used to estimate the number of (111) ordered domains terrace sites on different polycrystalline platinum samples, and the results are compared to those obtained with bismuth irreversible adsorption.

[Presurgical orthopedic treatment for cleft lip and palate]

INTRODUCTION

A multidisciplinary approach with several specialits allows a complete treatment for Cleft Lip and Palate. We show our experience in presurgical orthopedic treatment in these patients, their advantages, their problems and the results.

MATERIAL AND METHODS

Since 1999 presurgical orthopedy has been applied to 12 patients (3 bilateral cleft lip and palate and 9 unilateral cleft lip and palate). This approach was applied when there was a long distance between the alveolar segments. A palate mould and the location of Latham's appliance have been made in the operating room under general anesthesia. The patients were controlled by the orthodoncist and Latham's appliance was removed when cleft lip was closed.

RESULTS

Latham's appliance was kept for 4-7 weeks with once a week controls until the distance between the maxillary segments was less than 1 mm; in bilateral cases of cleft lip and palate the premaxilla was moved between lateral segments. Then, lip closure and nasoplasty was made and, sometimes, an obturador was placed.

CONCLUSIONS

Latham's appliance permit to achieve a perfect alignment of alveolar segments decreasing the soft tissues tension and facilitating the lip surgery, thus, a better aesthetic and functional results can be achieved. A more anatomic position of palate can be made and easier future orthopedic treatments are possible.