ABSTRACT
The multi-principal element alloy nanoparticles (MPEA NPs), a new class of nanomaterials, present a highly rewarding opportunity to explore new or vastly different functional properties than the traditional mono/bi/multimetallic nanostructures due to their unique characteristics of atomic-level homogeneous mixing of constituent elements in the nanoconfinements. Here, the successful creation of NiCoCr nanoparticles, a well-known MPEA system is reported, using ultrafast nanosecond laser-induced dewetting of alloy thin films. Nanoparticle formation occurs by spontaneously breaking the energetically unstable thin films in a melt state under laser-induced hydrodynamic instability and subsequently accumulating in a droplet shape via surface energy minimization. While NiCoCr alloy shows a stark contrast in physical properties compared to individual metallic constituents, i.e., Ni, Co, and Cr, yet the transient nature of the laser-driven process facilitates a homogeneous distribution of the constituents (Ni, Co, and Cr) in the nanoparticles. Using high-resolution chemical analysis and scanning nanodiffraction, the environmental stability and grain arrangement in the nanoparticles are further investigated. Thermal transport simulations reveal that the ultrashort (≈100 ns) melt-state lifetime of NiCoCr during the dewetting event helps retain the constituent elements in a single-phase solid solution with homogenous distribution and opens the pathway to create the unique MPEA nanoparticles with laser-induced dewetting process.
ABSTRACT
The study of interfacial Dzyaloshinskii-Moriya interaction (DMI) in perpendicularly magnetized structurally asymmetric heavy metal/ferromagnet multilayer systems is of high importance due to the formation of chiral magnetic textures in the presence of DMI. Here, we report the impact of cobalt oxidation at the Co/AlOxinterface in Pt/Co/AlOxtrilayer structures on the DMI by varying the post-growth annealing time, Al thickness and substrate. To quantify DMI we employed magneto-optical imaging of the asymmetric domain wall expansion, hysteresis loop shift, and spin-wave spectroscopy techniques. We further correlated the Co oxidation with low-temperature Hall effect measurements and x-ray photoelectron spectroscopy. Our results emphasize the importance of full characterization of the magnetic films that could be used for magnetic random access memory technologies when subjected to the semiconductor temperature processing conditions, as the magnetic interactions are critical for device performance and can be highly sensitive to oxidation and other effects.
ABSTRACT
INTRODUCTION: Although increased taxation on sugar-sweetened beverages (SSBs) and warning labels on their packaging have been successful in other countries, India has not implemented these. It is imperative to understand the user perspectives before implementation, regarding which almost no information exists. OBJECTIVES: To assess the awareness and perceptions of people regarding taxation and health warnings on SSB packaging, and to determine the factors associated with these. METHODOLOGY: This cross-sectional study was conducted in the general out-patient clinic of a public tertiary care hospital in Bhopal, India, between April and November 2018. Patients and accompanying persons ≥15 years of age and attending the clinic were included. Severely ill patients were excluded. Exit interviews were conducted after the clinical consultation using a pre-tested semi-structured interview schedule. Data were analyzed using IBM SPSS version 21. RESULTS: Out of the 503 participants interviewed, three-fourths had never heard of taxes on SSBs and had never seen any health warning on SSB packaging. Most participants (96.6%) wanted some health warning to be present on the packaging. Majority of them (69.3%) wanted both textual and pictorial warnings. Close to half of those who wanted a pictorial warning to be present opined that it should occupy <25% of the surface area of the packaging. Multivariable analysis showed that participants aged <25 years and females were not in favor of tax increment. CONCLUSION: Government policies should also focus on user perspectives and preferences before deciding to increase tax on SSBs or introducing mandatory health warnings on SSBs.