Ultrafast switching in spin field-effect transistors based on borophene nanoribbons.

Borophene, owing to the high mobility and long spin coherent length of its carriers, presents significant opportunities in ultrafast spintronics. In this research, we investigate the spin-dependent conductance of a Datta-Das field-effect transistor (FET) based on an armchair ß12-borophene nanoribbon (BNR) using the tight-binding (TB) Hamiltonian in combination with the non-equilibrium Green's function (NEGF) method. The spin FET electrodes are magnetized by ferromagnetic (FM) insulators arranged in both parallel and anti-parallel configurations. This device acts as a controllable spin filter in the presence of Rashba spin-orbit coupling (SOC) for both configurations and its spin current is well modulated by a gate voltage and the strength of the Rashba SOC. For anti-parallel configurations, an energy gap emerges within a certain range of incoming electron energy which can disappear for electrons with flipped spin under the Rashba SOC. Furthermore, our findings indicate that the electron-electron (e-e) interaction helps the spin precession of electrons injected into the spin FET channel, thereby strengthening the Rashba SOC effect. Notably, a gate voltage can adjust the current-voltage (I-V) characteristics of this device. Finally, our calculations demonstrate that under the same conditions, the current magnitude and Ion/Ioff ratio of borophene spin FETs are several times higher than those of graphene and silicene spin FETs.

Prevalence and causes of visual impairment and blindness in Sistan-va-Baluchestan Province, Iran: Zahedan Eye Study.

AIM: To determine the prevalence and causes of visual impairment and blindness in the Sistan-va-Baluchestan Province of Iran. METHODS: A population-based cross-sectional study with a multistage cluster sampling technique was used to identify the study subjects. Visual acuity (VA) was defined for all participants aged >or=10 years. Participants with a VA of <20/60 were examined by an ophthalmologist to determine the causes of low vision or blindness. RESULTS: 5446 (84.0%) of the invited people were examined. The prevalence of visual impairment (VA <20/60) was 6.81% (95% CI 5.91% to 7.71%) and of bilateral blindness (VA <3/60) was 0.79% (95% CI 0.50% to 1.08%). Visual impairment increased with age and illiteracy. Bilateral blindness doubled in women aged >40 years. The causes of visual impairment and blindness were cataract (37.7%), corneal opacity (15.0%), amblyopia (15.0%), glaucoma (5.7%) and hyperopia (5.0%). 39.5% of the visual impairment cases were potentially curable. CONCLUSION: The estimated magnitude of visual impairment and blindness was much higher than our expectations. Further investigation of the pattern of vision loss in women and children, particularly as a result of trachoma and amblyopia, is warranted. Implementation of measures to treat curable cases of the study population can improve the situation in the region dramatically.