Nanoscale Size Effects on Push-Pull Fe-O Hybridization through the Multiferroic Transition of Perovskite ϵ-Fe2O3.

Multiferroics have tremendous potential to revolutionize logic and memory devices through new functionalities and energy efficiencies. To reach their optimal capabilities will require better understanding and enhancement of the ferroic orders and couplings. Herein, we use ϵ-Fe2O3 as a model system with a simplifying single magnetic ion. Using 15, 20, and 30 nm nanoparticles, we identify that a modified and size-dependent Fe-O hybridization changes the spin-orbit coupling and strengthens it via longer octahedra chains. Fe-O hybridization is modified through the incommensurate phase, with a unique two-step rearrangement of the electronic environment through this transition with attraction and then repulsion of electrons around tetrahedral Fe. Interestingly, size effects disappear in the high-temperature phase where the strongest Fe-O hybridization occurs. By manipulating this hybridization, we tune and control the multiferroic properties.

Terahertz antireflection coatings employing off-the-shelf adhesive tapes.

We demonstrate the feasibility of making antireflection coatings (ARCs) for terahertz (THz) light using multilayered polymer films from commercial adhesive tapes. Efficient and low-cost ARCs in the THz range are not conveniently available. Our economical approach can mitigate many of the experimental challenges posed by Fresnel reflection. Harnessing a time-domain THz spectrometer, we demonstrate the performance of several types of multilayer coatings on a variety of substrates. By varying layer stacking and thicknesses, spectral performance can be tuned and optimized for specific applications. Good agreement is found between experimental measurement and analytic calculations evaluating the performance of these multilayer tape ARCs.

Prevalence of orthorexia nervosa is less than 1 %: data from a US sample.

PURPOSE: Orthorexia nervosa, or pathological dieting based on being "healthy," has been of growing interest. Clinical data are limited to less than a half-dozen case studies reporting instances of medical problems due to healthful eating. However, more than a dozen studies using a measure to identify orthorexia, the ORTO-15, report very high prevalence rates in non-clinical samples. Point prevalence rates are reported from 6 % to nearly 90 %. Such variability could be due to cultural issues or psychometric problems with the instrument. This study examines prevalence rate of orthorexia in a US sample. METHOD: The ORTO-15 was administered to 275 US college students along with other questions regarding diet, exercise, and health. RESULTS: While the ORTO-15 indicated a prevalence rate of 71 %, only 20 % of the sample endorsed a dietary practice of removing a particular food type (e.g. meat) from their diet. Those who endorsed following a vegan diet had the highest (less pathological) mean ORTO-15 score. Further, when classifying participants based on their seriousness about healthy eating and whether their diet had led to impairment in everyday activities and medical problems, less than 1 % of the sample fell into such a category. CONCLUSION: As in other countries, a large proportion of a non-clinical US sample scored in the orthorexia range on the ORTO-15. However, this instrument is likely unable to distinguish between healthy eating and pathologically healthful eating. Our estimate is that orthorexia nervosa like anorexia nervosa and bulimia nervosa, is not a common condition.