Design and fabrication of a lightweight 3D first surface mirror aluminized by DC magnetron sputtering.

Aluminum thin films were deposited on a 3D prototype employing the direct current magnetron sputtering technique to fabricate a lightweight 3D first surface mirror. Before the aluminizing, the surface of the prototypes was evaluated with interferometry and atomic force microscope (AFM). The thin films were characterized using profilometry, UV-Vis spectroscopy, x-ray diffraction, AFM, x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. High adherence and homogeneous deposition of the aluminum's thin films were achieved. In addition, the purity of the material was confirmed by XPS analysis.

Anharmonic contribution to the stabilization of Mg(OH)2 from first principles.

Geometrical and vibrational characterization of magnesium hydroxide was performed using density functional theory. Four possible crystal symmetries were explored: P3[combining macron] (No. 147, point group -3), C2/m (No. 12, point group 2), P3m1 (No. 156, point group 3m) and P3[combining macron]m1 (No. 164, point group -3m) which are the currently accepted geometries found in the literature. While a lot of work has been performed on Mg(OH)2, in particular for the P3[combining macron]m1 phase, there is still a debate on the observed ground state crystal structure and the anharmonic effects of the OH vibrations on the stabilization of the crystal structure. In particular, the stable positions of hydrogen are not yet defined precisely, which have implications in the crystal symmetry, the vibrational excitations, and the thermal stability. Previous work has assigned the P3[combining macron]m1 polymorph as the low energy phase, but it has also proposed that hydrogens are disordered and they could move from their symmetric position in the P3[combining macron]m1 structure towards P3[combining macron]. In this paper, we examine the stability of the proposed phases by using different descriptors. We compare the XRD patterns with reported experimental results, and a fair agreement is found. While harmonic vibrational analysis shows that most phases have imaginary modes at 0 K, anharmonic vibrational analysis indicates that at room temperature only the C2/m phase is stabilized, whereas at higher temperatures, other phases become thermally competitive.

In-silico study of the adsorption of H2, CO and CO2 chemical species on (TiO2)n n=15-20 clusters: The (TiO2)19 case as candidate promising.

In order to obtain an adsorption tendency of H2, CO and CO2 molecules on (TiO2)n n = 15-20 clusters, DFT calculations were carried out to evaluate the interaction among these systems. The (TiO2)19 cluster emerges as the best candidate to storage these chemical species. Then, two adsorption sites were considered to attach these molecules onto (TiO2)19 cluster: through of surface formed by i) titanium and ii) oxygen atoms, respectively. The adsorption energy values are more favored for case 1 than the case 2, due to short distances between titanium atom and these chemical species. In this sense, the larger values of chemisorption are related to great decreasing of values of vibrational modes for gases isolated respect to those bonded to bare cluster. In general, the values of electronic gap do not suffer drastic changes, however the HOMO iso-surfaces are displayed in different way for both cases, and LUMO is located at center of cluster for the whole set of systems analyzed in this study. The electronic transference occurs from chemical species toward atoms at adsorption site, in all systems. These results reveal that this (TiO2)19 cluster is good candidate to storage or sense different kind of gases; thereby, this system can be used as a hydrogen storage device for energy green applications.

Impact of the implementation of a Sepsis Code Program in medical patient management: a cohort study in an Internal Medicine ward.

OBJECTIVE: Sepsis is the main cause of death in hospitals and the implementation of diagnosis and treatment bundles has shown to improve its evolution. However, there is a lack of evidence about patients attended in conventional units. METHODS: A 3-year retrospective cohort study was conducted. Patients hospitalized in Internal Medicine units with sepsis were included and assigned to two cohorts according to Sepsis Code (SC) activation (group A) or not (B). Baseline and evolution variables were collected. RESULTS: A total of 653 patients were included. In 296 cases SC was activated. Mean age was 81.43 years, median Charlson comorbidity index (CCI) was 2 and 63.25% showed some functional disability. More bundles were completed in group A: blood cultures 95.2% vs 72.5% (p <0.001), extended spectrum antibiotics 59.1% vs 41.4% (p < 0.001), fluid resuscitation 96.62% vs 80.95% (p < 0.001). Infection control at 72 hours was quite higher in group A (81.42% vs 55.18%, odds ratio 3.55 [2.48-5.09]). Antibiotic was optimized more frequently in group A (60.77% vs 47.03%, p 0.008). Mean in-hospital stay was 10.63 days (11.44 vs 8.53 days, p < 0.001). Complications during hospitalization appeared in 51.76% of patients, especially in group B (45.95% vs 56.58%, odds ratio 1.53 [1.12-2.09]). Hospital readmissions were higher in group A (40% vs 24.76%, p < 0.001). 28-day mortality was significantly lower in group A (20.95% vs 42.86%, odds ratio 0.33 [0.23-0.47]). CONCLUSIONS: Implementation of SC seems to be effective in improving short-term outcomes in IM patients, although therapy should be tailored in an individual basis.

Ideal strength on clusters from first principles: the Ti(13) case.

The mechanical behavior of a Ti(13) cluster, based on total energy mechanical quantum calculations is studied. The cluster geometry has been optimized and good agreement with previous reports has been found. Axial strain is applied along one of the principal axes and the changes on the energetic and vibrational properties of the system are followed. To characterize the cluster stability as a function of strain, vibrational frequencies and total energy have been calculated, to obtain the cluster maximum load tolerance for compression (C) and tensile (T). If the maximum load is defined through a vibrational instability, it happens to be two and half, and three times larger than when the maximum total energy is considered (C and T respectively). As a result of the induced strain along of the C(5) symmetry element, the cluster changes its point group symmetry from I(h) to D(5d), with an energy difference of 1.17 eV (for compression) and 0.33 eV (for tension) with respect to the ground state geometry. The electronic changes are also characterized, as function of the strain, by following the modifications of the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and changes on the total atomic population.

Adsorption of CO and NO molecules onto pentagonal clusters of aluminum: a DFT study.

DFT calculations were carried out in order to determine the electronic and structural properties of pentagonal Al n (I h and D 5d symmetries), Al n -CO, and Al n -NO clusters, where n = 7, 13, 19, 43, or 55 atoms. As n was increased, the bare clusters were found to exhibit a transition in electronic behavior (from semiconductor to conductor) at n = 43 atoms. Clusters with a bound CO or NO molecule also showed this behavior, although their HOMO-LUMO energy gaps were smaller than those for the corresponding bare clusters. As the size of the Al n -CO or Al n -NO cluster increased, the presence of extra p electrons improved the capacity of the cluster to adsorb a CO or NO molecule and resulted in an increase in the electronic charge directed from the aluminum atom at the adsorption site to the adsorbed species (CO or NO), thus strengthening the Al-CO or Al-NO bond. Furthermore, the Al n CO and Al n NO clusters with n = 43 and 55 exhibited chemisorption, as did the Al13-NO cluster; the other clusters presented physisorption, based on their adsorption energies. The tendency to adsorb either CO or NO increased with the size of the aluminum cluster. Graphical Abstract Adsorption of CO and NO molecules onto pentagonal clusters of aluminum: a DFT study.

Thermal diffusivity of nanofluids containing Au/Pd bimetallic nanoparticles of different compositions.

Colloidal suspensions of bimetallic Au/Pd nanoparticles were prepared by simultaneous reduction of the metal ions from their corresponding chloride salts with polymer (PVP) stabilizer. Thermal properties of water containing bimetallic nanoparticles with different nominal compositions (Au/Pd = 12/1, 5/1, 1/1, 1/5) were measured using the mode mismatched dual-beam thermal lens technique to determine the effect of particle composition on the thermal diffusivity of the nanofluids. The characteristic time constant of the transient thermal lens was estimated by fitting the experimental data to the theoretical expression for transient thermal lens. The thermal diffusivity of the nanofluids (water, containing Au/Pd bimetallic nanoparticles) is seen to be strongly dependent on the composition of the particles. The maximum diffusivity was achieved for the nanoparticles with highest Au/Pd molar ratio. A possible mechanism for such high thermal diffusivity of the nanofluids with bimetallic particles is given. UV-Vis spectroscopy, TEM and high-resolution electron microscopy (HREM) techniques were used to characterize the Au/Pd bimetallic nanoparticles.