First-principles DFT Insights into the adsorption of hydrazine on bimetallic β1-NiZn catalyst: implications for direct hydrazine fuel cells

We present a systematic first-principles density functional theory study with dispersion corrections (DFT-D3) of hydrazine adsorption on the experimentally observed (111), (110) and (100) surfaces of the binary β1-NiZn alloy. A direct comparison has been drawn between the bimetallic and monometallic Ni and Zn counterparts to understand the synergistic effect of alloy formation. The hydrazine adsorption mechanism has been characterised through adsorption energies, Bader charges, the d-band centre model, and the coordination number of the active site - which is found to dictate the strength of the adsorbate-surface interaction. The bimetallic β1-NiZn nanocatalyst is found to exhibit higher activity towards adsorption and activation of hydrazine compared to the monometallic Ni and Zn counterparts. The Ni-sites of the bimetallic NiZn surfaces are found to be generally more reactive than Zn sites, which is suggested to be due to the higher d-band centre of -0.13 eV (closer to the Fermi level), forming higher energy anti-bonding states through Ni-N interactions. The observed synergistic effects derived from surface composition and electronic structure modification from Ni and Zn alloying should provide new possibilities for the rational design and development of low-cost bimetallic Ni-Zn alloy catalysts for direct hydrazine fuel cell (DHFC) applications

Theoretical Insights into the hydrogen evolution reaction on the Ni3N electrocatalyst

Ni-based catalysts are attractive alternatives to noble metal electrocatalysts for the hydrogen evolution reaction (HER). Herein, we present a dispersion-corrected density functional theory (DFT-D3) insight into HER activity on the (111), (110), (001), and (100) surfaces of metallic nickel nitride (Ni3N). A combination of water and hydrogen adsorption was used to model the electrode interactions within the water splitting cell. Surface energies were used to characterise the stabilities of the Ni3N surfaces, along with adsorption energies to determine preferable sites for adsorbate interactions. The surface stability order was found to be (111) < (100) < (001) < (110), with calculated surface energies of 2.10, 2.27, 2.37, and 2.38 Jm−2, respectively. Water adsorption was found to be exothermic at all surfaces, and most favourable on the (111) surface, with Eads = −0.79 eV, followed closely by the (100), (110), and (001) surfaces at −0.66, −0.65, and −0.56 eV, respectively. The water splitting reaction was investigated at each surface to determine the rate determining Volmer step and the activation energies (Ea) for alkaline HER, which has thus far not been studied in detail for Ni3N. The Ea values for water splitting on the Ni3N surfaces were predicted in the order (001) < (111) < (110) < (100), which were 0.17, 0.73, 1.11, and 1.60 eV, respectively, overall showing the (001) surface to be most active for the Volmer step of water dissociation. Active hydrogen adsorption sites are also presented for acidic HER, evaluated through the ΔGH descriptor. The (110) surface was shown to have an extremely active Ni–N bridging site with ΔGH = −0.05 eV

DFT and experimental investigations on the photocatalytic activities of NiO nanobelts for removal of organic pollutants

NiO nanobelts synthesized using the hydrothermal method are explored for photocatalytic degradation of organic pollutants like RhB, MO, MB, and CV. The XPS analysis confirmed the formation of the stoichiometric NiO nanobelts. Few micrometer long cubic crystalline NiO nanobelts of the average thickness of ∼75 nm delivered a bandgap of 4.07 eV. The FTIR studies revealed that the mesoporous NiO nanobelts delivered stable photocatalytic activities after controlled irradiation under a xenon lamp. The kinetic studies showed the 79.1, 82.7, 76.7, and 89% degradation of MO, MB, CV, and RhB after 140 min at the rate constants (k) of 0.007, 0.008, 0.009, and 0.012 min−1, respectively. Complementary first-principles Density Functional Theory (DFT) and scavenging studies revealed the chemical picture and influence of the , and photogenerated from NiO nanobelts in the photocatalytic degradation of organic dyes. These studies corroborate the use of the NiO nanobelts in the stable and eco-friendly photocatalytic degradation activities of a wide range of organic pollutants

Dark blood late enhancement imaging.

Background Bright blood late gadolinium enhancement (LGE) imaging typically achieves excellent contrast between infarcted and normal myocardium. However, the contrast between the myocardial infarction (MI) and the blood pool is frequently suboptimal. A large fraction of infarctions caused by coronary artery disease are sub-endocardial and thus adjacent to the blood pool. It is not infrequent that sub-endocardial MIs are difficult to detect or clearly delineate. Methods In this present work, an inversion recovery (IR) T2 preparation was combined with single shot steady state free precession imaging and respiratory motion corrected averaging to achieve dark blood LGE images with good signal to noise ratio while maintaining the desired spatial and temporal resolution. In this manner, imaging was conducted free-breathing, which has benefits for image quality, patient comfort, and clinical workflow in both adults and children. Furthermore, by using a phase sensitive inversion recovery reconstruction the blood signal may be made darker than the myocardium (i.e., negative signal values) thereby providing contrast between the blood and both the MI and remote myocardium. In the proposed approach, a single T1-map scout was used to measure the myocardial and blood T1 using a MOdified Look-Locker Inversion recovery (MOLLI) protocol and all protocol parameters were automatically calculated from these values within the sequence thereby simplifying the user interface. Results The contrast to noise ratio (CNR) between MI and remote myocardium was measured in n = 30 subjects with subendocardial MI using both bright blood and dark blood protocols. The CNR for the dark blood protocol had a 13 % loss compared to the bright blood protocol. The CNR between the MI and blood pool was positive for all dark blood cases, and was negative in 63 % of the bright blood cases. The conspicuity of subendocardial fibrosis and MI was greatly improved by dark blood (DB) PSIR as well as the delineation of the subendocardial border. Conclusions Free-breathing, dark blood PSIR LGE imaging was demonstrated to improve the visualization of subendocardial MI and fibrosis in cases with low contrast with adjacent blood pool. The proposed method also improves visualization of thin walled fibrous structures such as atrial walls and valves, as well as papillary muscles

Highly active methanol oxidation electrocatalyst based on 2D NiO porous nanosheets:a combined computational and experimental study

Two-dimensional (2D) nanostructures are attractive candidates for electrocatalytic applications owing to their excellent mechanical flexibility and large exposed surfaces. In this work, we present ultra-thin 2D NiO porous nanosheets prepared by a simple, economical and green experimental method (hydrothermal, freeze-drying, and sintering) as efficient electrocatalysts for direct methanol fuel cell (DMFC) application. Benefiting from the ultra-thin 2D framework and porous nanostructure, the 550-NiO catalyst (annealed at 550 °C) exhibit higher current density (12.54mA cm−2) and faster charge transfer in the catalytic process, due to its abundant solid state redox couples (Ni2+/Ni3+= 0.991), suitable oxygen defects and surface coverage of redox species (2.90 × 10−7mol cm−2). First-principles density functional theory calculations were employed to provide mechanistic insights into the methanol oxidation reaction over the NiO catalyst via methanol dehydrogenation to CO involving O–H and C–H bond scissions, and subsequently, CHO oxidation with OH. The most plausible reaction pathway of methanol oxidation on NiO (100) is predicted to be CH3OH → CH3O → CH2O → CHO → CHOOH → COOH → CO2. The reported facile, simple, low-cost and method provides an avenue for the rational design and synthesis of 2D NiO porous nanostructured electrode materials for DMFC and beyond

Choosing party leaders: Anglophone democracies, British parties and the limits of comparative politics

Since 1965, Britain’s major political parties have radically, and repeatedly, changed the ways in which they choose their leaders. Building on a recent comparative study of party leadership selection in the five principal Anglophone (‘Westminster’) parliamentary democracies (Cross and Blais, 2012a), this article first outlines a theoretical framework that purports to explain why the major parties in three of those countries, including Britain, have adopted such reform. It then examines why five major British parties have done so since 1965. It argues that, while Cross and Blais’ study makes a significant contribution to our knowledge and understanding of processes of party leadership selection reform in Anglophone parliamentary democracies, it has limited explanatory power when applied to changes enacted by the major parties in modern and contemporary Britain. Instead, the adoption of such reform in the British context is ultimately best understood and explained by examining both the internal politics and external circumstances of individual parties

Reciprocated electrochemical and DFT investigations of iron selenide: mechanically bendable solid-state symmetric supercapacitor

Enhanced energy storing capability with the aid of unique nanostructured morphology is beneficial to enrich the effective path for the development of energy storing capability of supercapacitors. Scheming earth abundant and low-cost transitional metal selenides (TMSs) with enhanced charge transfer capability with pronounced stability is still a challenge. Herein, state of art is presented for iron selenide with nanoflakes surface architecture synthesized with aid of simple, industry-scalable, and ionic layer controlled chemical approach namely; successive ionic layer adsorption and reaction (SILAR) method. Iron selenide electrode yields capacitance of 671.7 F/g at 2 mV/s scan rate and 434.6 F/g at 2 mA/cm2 current density through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) studies, respectively with 91.9% cyclic retention at 4000 cycles. Developed bendable solid-state supercapacitor reveals remarkable power density of 5.1 kW/kg with outstanding deformation tolerance including practical demo to run small fan, demonstrating capability for advanced energy storage applications. Complementary first-principles Density Functional Theory (DFT) approach used to achieve reciprocity with experimental supercapacitive performance through the understandings of the electronic structure

Experimental and computational studies of sonochemical assisted anchoring of carbon quantum dots on reduced graphene oxide sheets towards the photocatalytic activity

Herein, carbon quantum dots (CQDs) are anchored on reduced graphene oxide (rGO) sheets by sonochemical assisted method. The developed carbon quantum dots/reduced graphene oxide (CQDs/rGO) catalyst shows enhancement in the photocatalytic degradation of methylene blue and methyl orange under visible light compared to that of individual CQDs and rGO components. The improved performance of the CQDs/rGO catalyst has been attributed to efficient separation of photogenerated charge carriers as studied by photoluminescence studies and to increase in the surface area as studied by Brunauer-Emmett-Teller method. The photocatalytic degradation is studied in detail by varying catalyst loading, dye concentration and the rate constant is determined by first order kinetics. The enhancement in photocatalytic activity of CQDs/rGO catalyst is validated by first principles density functional theory (DFT) calculations which shows the enrichment in density of states thereby decreasing the work function

Facial Cosmetics and Attractiveness: Comparing the Effect Sizes of Professionally-Applied Cosmetics and Identity

Forms of body decoration exist in all human cultures. However, in Western societies, women are more likely to engage in appearance modification, especially through the use of facial cosmetics. How effective are cosmetics at altering attractiveness? Previous research has hinted that the effect is not large, especially when compared to the variation in attractiveness observed between individuals due to differences in identity. In order to build a fuller understanding of how cosmetics and identity affect attractiveness, here we examine how professionally-applied cosmetics alter attractiveness and compare this effect with the variation in attractiveness observed between individuals. In Study 1, 33 YouTube models were rated for attractiveness before and after the application of professionally-applied cosmetics. Cosmetics explained a larger proportion of the variation in attractiveness compared with previous studies, but this effect remained smaller than variation caused by differences in attractiveness between individuals. Study 2 replicated the results of the first study with a sample of 45 supermodels, with the aim of examining the effect of cosmetics in a sample of faces with low variation in attractiveness between individuals. While the effect size of cosmetics was generally large, between-person variability due to identity remained larger. Both studies also found interactions between cosmetics and identity-more attractive models received smaller increases when cosmetics were worn. Overall, we show that professionally- applied cosmetics produce a larger effect than self-applied cosmetics, an important theoretical consideration for the field. However, the effect of individual differences in facial appearance is ultimately more important in perceptions of attractiveness