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In this work, the effect of lithium hydroxide (LiOH) amalgamation on the properties of polyvinyl alcohol thermoplastic membranes, obtained by the solvent casting method, is presented. FTIR and Raman spectroscopy show the effect of Li + on vibrations of C=O, C–O and O–H functional groups. Moreover, DRX analysis confirmed the semi-crystalline nature of the samples. The density functional theory indicates an insulator–metal transition due to the lithium incorporation in the polymer. Moreover, the formation energy and structural properties have also been calculated to understand the PVA–Li interaction. The complex impedance study at room temperature indicates an improvement in the resistance values of the membranes, with the increase of the lithium content, up to 7% of LiOH (7 * 102 Ω). The results reveal the importance of this type of material as candidates in solid-state electrolytes. [ABSTRACT FROM AUTHOR]

We probed the structural modifications and electronic behavior of composites obtained from the admixture of a biphasic titanate ceramic system (Na2Ti3O7/Na2Ti6O13) with a poly(o-methoxyaniline, POMA) matrix. The composites were obtained by the addition of Na2Ti3O7/Na2Ti6O13to a POMA matrix in mass concentrations from 0 to 35%. The sodium titanates were synthesized by means of sonochemistry, while the polymer was obtained by conventional chemical polymerization. The structural analysis carried by XRD, FTIR and UV-Vis indicated mostly the presence of POMA, though the titanates could be identified in the composites with higher concentration. The XRD diffractograms showed narrow reflections that could be correlated to the Na2Ti6O13 phase and hydrogen titanates, whose presence indicates a process of partial substitution of H+ for Na+ ions. While the thermal degradation of the polymeric chains starts near 150 °C, the thermogravimetric and differential thermogravimetric (TG/dTG) analysis revealed that the presence of sodium titanates enhances the thermal stability of the composites. Finally, the addition of the biphasic ceramic to the composite increases the electrical resistivity drastically, from ≈ 102 Ω cm in the pure POMA to ≈ 104 Ω cm in the 35% composite. [ABSTRACT FROM AUTHOR]

In this work, the variation in the structural and electrical properties of lithium-doped sodium titanate, obtained from an ultrafast (15 min) microwave-assisted synthesis has been reported. X-ray diffraction and Rietveld analysis have been done to identify the present phases, their composition, and lattice parameters. Na2Ti3O7 was identified as the major phase, while Na2Ti6O13 was obtained as a secondary phase in all samples. The phase composition usually varies depending on the content of the doping element. In the sample with 0.5% lithium ions, an additional phase corresponding to NaLiTi3O7 appeared. The microstructure of the ceramic samples showed an increase in the grains size and the appearance of small particles on the surface of the grains. This effect becomes more evident for the samples with 0.5% Li. Finally, the electrical properties of the ceramic samples studied were favored with an increase in doping and σdc values of 1.94 × 10− 5 S cm− 1, 2.51 × 10− 5 S cm− 1, and 4.00 × 10− 5 S cm− 1 were determined for Na2 − xLixTi3O7 with x = 0.0%, 0.1%, 0.5% of Li+. [ABSTRACT FROM AUTHOR]

The functional diversity of echinoderms has been understudied, even though these organisms are critical components of various ecosystems, including coral reefs and hard-bottom benthic communities. Additionally, there are only a few papers relating the protection level of marine protected areas (MPAs) with functional diversity. In this study, we calculate the functional diversity of echinoids and asteroids in 11 coral and rocky reefs with different protection levels across the Mexican Pacific. We recorded the abundance of 15 echinoderm species comprising seven echinoid and eight asteroid species. More than 30 morphological and ecological traits of the censused species were evaluated to calculate two functional diversity indices: Rao's quadratic entropy index (FDQ) and functional richness (FRic). Latitudinal patterns of functional diversity differed between groups. Asteroids showed the highest FDQ and FRic values in the Gulf of California. Echinoids showed FDQ peaks at the highest (Bahía de los Ángeles; 28° 56′, − 113° 30′), and the lowest latitude (Bahías de Huatulco; 15° 43′, − 98° 08′) sites. The Ixtapa-Zihuatanejo site (17° 39′, − 101° 36′) had the highest FRic values. Generalized linear mixed models showed that protection level did not have any significant effect on FDQ or FRic. Latitude, on the other hand, did have a significant effect on asteroid functional diversity, although no significant effects were found for echinoids. The lack of an effect of protection level, and the support of a latitudinal gradient in terms of both taxonomic and functional diversity, has important implications for conservation efforts, supporting the idea of a protected area network to maintain adequate regional biodiversity. [ABSTRACT FROM AUTHOR]

In this work, γ-CoOOH was successfully synthesized from α-Co(OH)2, as a precursor, by electrochemical oxidation, without the use of any additives or high temperatures. The films were morphologically and structurally characterized using X-Ray Diffraction and Scanning Electronic Microscopy techniques. Cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques were used for the electrochemical characterization. The XRD and Raman techniques allowed confirming the effective conversion of α-Co(OH)2 to γ-CoOOH. The γ-CoOOH films are composed of hexagonal platelets on a steel plate substrate. The deposited films exhibit excellent electrochemical performance at different current densities, and good cycling stability of 95.1% after 2000 cycles of charge/discharge. The maximum specific capacity of 89.3 mA h g−1 was achieved at a current density of 1 mA g−1. The results suggest a simple route to synthesize γ-CoOOH films, which are promising as an electrode material for application in energy storage devices. [ABSTRACT FROM AUTHOR]

Nanostructured Ni(OH)2 was grown on the surface of a Ti plate via electrodeposition method. Analytical methods were employed to characterize the structure, morphology, and electrochemical performance of the samples. A voltammetry detailed study was used to determine the different contributions to the total stored charge. Based on the electrochemical impedance spectroscopy study, the results are discussed in terms of complex capacitance and complex power. The relaxation time constant of the systems and capacitance values at low frequency for different potentials were determined from complex capacitance plots. The Ni(OH)2 sample exhibited excellent electrochemical performance at different current densities and good cycling ability, 99.3% of the initial capacity (951.5 mA h g−1) remains after 1000 cycles of charge-discharge. [ABSTRACT FROM AUTHOR]

Na2Ti3O7 ceramic materials have been widely used in sodium-ion battery applications with relative good results; however, there are still several studies that might be carried out in the improvement of the Na2Ti3O7 properties and the overall batteries’ performance. In this direction, we used sonochemical method following a thermal treatment in order to synthetized pure phase Na2Ti3O7 nanopowders. X-ray diffraction characterization revealed that Na2Ti3O7 is the primary phase in nanopowders and ceramic sample; although, a high level of amorphization was observed in the sonicated nanopowder without heat treatment process. Nanopowder-prepared ceramic sample showed a crystallite size of 50 nm after sintering at 900 °C for 1 h. The specific surface area, pore volume, and pore size were obtained from the B.E.T. measurements, being 51 m2 g−1, 0.07 cm3 g−1, and 55 Å, respectively. The capacitance values of the nanopowder-prepared ceramic sample were in the order of microfarad. The total energy of the system was used to determine relaxation time of the sample (τ0 = 31 ms). [ABSTRACT FROM AUTHOR]

Cliona vermifera is one of the most abundant excavating sponges in Mexican coral reefs, and represents a potential threat to their health. It appears to have limited dispersal potential, but, paradoxically, it is widespread over much of the 2000 km of Mexican Pacific waters, suggesting mechanisms of long-distance dissemination. Despite its ecological importance, nothing is known about its patterns of genetic structure and connectivity in space and time. In this study, we assess levels of genetic structure and test the hypothesis of limited dispersal and isolation by distance among coral reef systems in the Mexican Pacific. Genetic diversity levels were consistently low in DNA sequences from two mitochondrial genes and one nuclear gene; however, they revealed strong and significant genetic differentiation throughout the study region. Patterns of genetic differentiation from the slow-evolving mitochondrial, but not the nuclear, genes were geographic scale dependent. We found higher mitochondrial genetic similarity among localities at 10-100s km than at larger scales (100-1000s km). However, all samples were genetically differentiated at the nuclear locus, which is inconsistent with frequent long-distance dispersal. Significant isolation by distance is consistent with life history traits shared by boring sponges: a short larval period and larval philopatric behavior. The patterns of genetic differentiation in C. vermifera concur with those found in other sympatric coral species, and suggest the influence of community-wide ecological and genetic mechanisms on the genetic makeup of coral reef species in the Mexican Pacific. Fixed genetic differences suggest that the southern population of Oaxaca may be experiencing incipient speciation. [ABSTRACT FROM AUTHOR]

Coral reefs are the most complex and diverse of aquatic ecosystems. Their vulnerability and deterioration in the face of anthropogenic disturbance require the adoption of conservation and restoration efforts to maintain their resilience, for which connectivity is of paramount importance. Dispersal of meroplanktonic larval stages drives the levels of connectivity among coral populations and is influenced by the local current regime, the synchronization of spawning events, and the capacity of larvae to reach recruitment sites. This research aims to quantify the levels of connectivity among Pavona gigantea populations in the Mexican Pacific, using two mitochondrial genes and a nuclear gene. Mitochondrial genes were insufficiently variable to test geographical heterogeneity, whereas the more variable ( h ≥ 0.86) nuclear rDNA indicated significant geographic differentiation ( Φ = 0.159, P < 0.001) among five locations along the Mexican Pacific, but no evidence of isolation by distance. Gene flow was limited among most sampled locales, and the largest estimate suggested moderate and unidirectional gene flow from Huatulco Bays to La Paz Bay and Marietas Islands. We found partial agreement between the patterns of connectivity among localities and the general pattern of superficial oceanographic circulation of the region, particularly in reference with the expected influence of the northward flowing West Mexican Current. These results suggest a limited demographic connectivity among Pavona gigantea populations along the Mexican Pacific, mediated by passive larval transport, and highlight the difficulty of predicting connectivity patterns on the basis of highly variable oceanographic regimes and reproductive events. The limited connectivity is of consequence for the viability and vulnerability of local populations and should be considered in the management and conservation strategies in the region. [ABSTRACT FROM AUTHOR]

A method using artificial neural networks (ANNs) combined with Fourier Transform (FT) and Wavelet Transform (WT) was used to resolve overlapping electrochemical signals. This method was studied as a powerful alternative to traditional techniques such as principal component regression (PCR) and partial least square (PLS), typically applied to this kind of problems. WT and FT were applied to experimental electrochemical signals. These are two alternative methods to reduce dimensions in order to obtain a minimal recomposition error of the original signals with the least number of coefficients, which are utilized as input vectors on neural networks. Tl+ and Pb2+ mixtures were used as a proof system. In this paper, neural networks with a simple topology and a high predictive capability were obtained, and a comparative study using PLS and PCR was done, producing the neural models with the lowest RMS errors. By comparing the error distributions associated with all the different models, it was established that models based on FT and WT (with 11 coefficients) neural networks were more efficient in resolving this type of overlapping than the other chemometric methods. [ABSTRACT FROM AUTHOR]

The article presents a study which determines trace and heavy metal concentrations in San Andres lagoon in Tamaulipas, Mexico to identify the levels of metal pollution. The study uses a Perkin Elmer 2380 atomic absorption spectrophotometer equipped with HGA-400 graphite furnace to analyze the samples and a correlation of metal concentrations between water and oyster. Results show that metals are enriched in sediments and oysters.

Fracture of components of a total hip arthroplasty occur is a recognised complication. We report an unusual case in which the fracture occurred through the neck of a femoral component on a Lord type of total hip arthroplasty. [ABSTRACT FROM AUTHOR]

We probed the structural modifications and electronic behavior of composites obtained from the admixture of a biphasic titanate ceramic system (Na2Ti3O7/Na2Ti6O13) with a poly(o-methoxyaniline, POMA) matrix. The composites were obtained by the addition of Na2Ti3O7/Na2Ti6O13to a POMA matrix in mass concentrations from 0 to 35%. The sodium titanates were synthesized by means of sonochemistry, while the polymer was obtained by conventional chemical polymerization. The structural analysis carried by XRD, FTIR and UV-Vis indicated mostly the presence of POMA, though the titanates could be identified in the composites with higher concentration. The XRD diffractograms showed narrow reflections that could be correlated to the Na2Ti6O13 phase and hydrogen titanates, whose presence indicates a process of partial substitution of H+ for Na+ ions. While the thermal degradation of the polymeric chains starts near 150 °C, the thermogravimetric and differential thermogravimetric (TG/dTG) analysis revealed that the presence of sodium titanates enhances the thermal stability of the composites. Finally, the addition of the biphasic ceramic to the composite increases the electrical resistivity drastically, from ≈ 102 Ω cm in the pure POMA to ≈ 104 Ω cm in the 35% composite. [ABSTRACT FROM AUTHOR]

Bacteria, fungi, and plants have metabolic pathways for the utilization of nitrogen present in purine bases. In Klebsiella pneumoniae, the genes responsible for the assimilation of purine ring nitrogen are distributed in three separated clusters. We characterized the gene cluster involved in the metabolism of allantoate (genes KPN&#95;01761 to KPN&#95;01771). The functional assignments of HpxK, as an allantoate amidohydrolase, and of HpxU, as a regulator involved in the control of allantoate metabolism, were assessed experimentally. Gene hpxU encodes a repressor of the RpiR family that mediates the regulation of this system by allantoate. In this study, the binding of HpxU to the hpxF promoter and to the hpxU-hpxW intergenic region containing the divergent promoter for these genes was evidenced by electrophoretic mobility shift assays. Allantoate released the HpxU repressor from its target operators whereas other purine intermediate metabolites, such as allantoin and oxamate, failed to induce complex dissociation. Sequence alignment of the four HpxU identified operators identified TGAA-N8-TTCA as the consensus motif recognized by the HpxU repressor.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional housekeeping protein reported to be a target of several covalent modifications in many organisms. In a previous study, enterohemorrhagic (EHEC) and enteropathogenic (EPEC) Escherichia coli strains were shown to secrete GAPDH and the protein to bind human plasminogen and fibrinogen. Here we report that GAPDH of these pathogens is ADP-ribosylated either in the cytoplasm or in the extracellular medium. GAPDH catalyzes its own modification, which involves Cys-149 at the active site. ADP-ribosylation of extracellular GAPDH may play an important role in the host-pathogen interaction, as also proposed in other pathogens.