In this study, we present results of the electronic density of states (DOS) and bulk magnetic moment of iron (Fe), cobalt (Co) and their alloys (Fe
x
Co
1–
x
;
x
= 1.0, 0.95, …, 0.0). Density ...functional theory with the generalized gradient approximation was applied to obtain geometric and electronic properties. The methodology uses virtual crystal approximation, in conjunction with CASTEP module and the functionals PBE and PBESol of the molecular simulation program Material Studio. We optimized the geometry of the bulk (obtaining their lattice parameters), which the structure was used to determine the bulk magnetic moments. To determine the magnetic moment, we calculated the difference of the electronic DOS of the electrons with spin up and spin down. The geometric optimization and magnetic moment obtained in the present study are very similar to the experimental results, with a maximum error of 8%, which makes the present article interesting.
In recent years, the popularity of metal hydrides has increased considerably for hydrogen storage and their applications in hydrogen fuel cells. Their potential applications for clean energy are ...promissory. However, the temperatures required for adsorption and desorption are extremely high, which range between 500 and 700 K, making their use impractical. To overcome these difficulties, the following work considers using three hydride alloys: magnesium-aluminum (MgAl), magnesium-nickel (MgNi), and magnesium-zinc (MgZn). The Mg concentrations were set to be between 80 and 100 wt% in order to reduce the temperatures of adsorption and desorption in contrast with the temperatures of pure magnesium. The chemisorption and repulsion energies of the hydrogen molecule on the surface (110) of the different metallic alloys were studied at 0, 200, 400, 600, and 700 K, respectively. The study was based on the density functional theory (DFT), with the module DMol
3
of the molecular simulation program Materials Studio, which was used to obtain these energy values. The results confirm that adding aluminum, nickel, or zinc into magnesium matrix increases the chemisorption and decreases the energy repulsion values on surfaces of the metallic alloys, improving the effectiveness of the hydrogen storage.
In recent years, the popularity of metal hydrides has increased considerably for hydrogen storage and their applications in hydrogen fuel cells. Their potential applications for clean energy are ...promissory. However, the temperatures required for adsorption and desorption are extremely high, which range between 500 and 700 K, making their use impractical. To overcome these difficulties, the following work considers using three hydride alloys: magnesium-aluminum (MgAl), magnesium-nickel (MgNi), and magnesium-zinc (MgZn). The Mg concentrations were set to be between 80 and 100 wt% in order to reduce the temperatures of adsorption and desorption in contrast with the temperatures of pure magnesium. The chemisorption and repulsion energies of the hydrogen molecule on the surface (110) of the different metallic alloys were studied at 0, 200, 400, 600, and 700 K, respectively. The study was based on the density functional theory (DFT), with the module DMol3 of the molecular simulation program Materials Studio, which was used to obtain these energy values. The results confirm that adding aluminum, nickel, or zinc into magnesium matrix increases the chemisorption and decreases the energy repulsion values on surfaces of the metallic alloys, improving the effectiveness of the hydrogen storage.
Chromosomal instability as manifested by increases in aneuploidy and structural chromosome aberrations is believed to play a critical role in the intermediate to late stages in the development of ...cervical malignancies. The current study was designed to determine the role of tetraploidy in the formation of aneuploidy and ascertain the occurrence of these alterations during the earlier stages of cervical carcinogenesis. Cervical cell samples, with diagnoses ranging from Normal to high-grade lesions, (HSIL) were obtained from 143 women and were evaluated for chromosomal alterations using dual-probe fluorescence in situ hybridization. Cervical cells from a subset of the group were also evaluated for chromosomal instability in the form of micronuclei. The frequencies of cells exhibiting either tetrasomy or aneusomy for Chromosomes 3 and 17 increased significantly with disease progression and displayed distinctive patterns where aneusomy was rarely present in the absence of tetrasomy. The frequencies of micronuclei that formed through either chromosomal loss or breakage increased significantly in both the low-grade and high-grade diagnostic categories and were highly correlated with both the number of tetrasomic and aneusomic cervical cells. In addition, a unique chromosomal alteration involving a significant non-random loss of Chromosome 17 specific to near-tetraploid aneusomic cells (trisomy 17 and tetrasomy 3) was observed. We conclude that tetraploidy and chromosomal instability are related events occurring during the early stages of cervical carcinogenesis that predispose cervical cells to the formation of aneuploidy frequently involving the loss of Chromosome 17.
Recent research has focused on the control of the geometric shape of nanoparticles (NPs) to improve their catalytic activity for the oxygen reduction reaction (ORR) in PEM fuel cells. This work ...studies the effect of the Oam : Oac ratio on the size, morphology, and catalytic activity of several carbon-supported Ni-Pt nanomaterials. Electrochemical tests using ring-disk electrode techniques were used to evaluate the catalytic activity and peroxide formation toward the ORR in acid media. STEM, SEM, EDS, and XRD were performed to study the physical properties of the nanocatalysts synthesized. UV-vis and FTIR spectroscopy were used to characterize the metal-ligand complexes formed during the synthesis. Additionally, accelerated electrochemical degradation testing was undertaken to evaluate the stability of the catalysts. The best nanomaterial in terms of high catalytic activity and stability was chosen and applied as the cathode for fuel cell evaluations. Experimental results revealed that the exclusive use of Oam during the synthesis resulted in polyhedral nanoparticles with the best catalytic activity toward the ORR. On the other hand, an increase in Oac content caused a decrease in Ni content through the formation of a Ni
2+
:carboxylate complex which promotes nanoparticles smaller in size, variations in their morphology, and a decrease in their catalytic activity.
Systematic study on the variation of morphology, size and composition of Ni-Pt nanoparticles with higher catalytic activity towards oxygen reduction.
The aim of this work was to study the effect of a sequential extraction of proteins from nixtamalized corn (Zea mays L) on the thermal and rheological properties of the resulting dough (masa) from ...the residual components. Proteins were sequentially extracted from nixtamalized and control corn samples. Masas resulting after each protein fraction extraction were subjected to thermal analysis and rheological tests. The thermogram data suggested that, even though albumins and globulins were in small amount in corn samples cooked with lime, interactions albumins-lime and globulins-lime could probably be taking place and these interactions stabilized the starch crystals. However, zeins and glutelin-like proteins probably interacted with gelatinized starch, weakening its crystal integrity. Rheological characterization showed that all masas, behaved as “weak-gel- like materials”, with a predominating elastic behavior (G′ > G″), over the involved frequency range. The elastic rheological response might be attributed to the formation of a lime-polymerized protein-starch network and G′ and G″ were affected by the applied treatments.
•Masas from control and nixtamalized corn were prepared after protein fractions extraction.•Protein fractions were analyzed by SDS electrophoresis.•Albumins and globulins stabilized starch crystals increasing gelatinization enthalpy in nixtamalized samples.•All masa samples behaved as weak viscoelastic gels, with predominance of the storage modulus.•Thermal and rheological differences were due to lime-polymerized protein-starch network.
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