ABSTRACT
Multiple sclerosis is the most common autoimmune disease affecting the central nervous system (CNS) worldwide. Multiple sclerosis involves inflammatory demyelination of nerve fibers in the CNS, often presenting with recurrent episodes of focal sensory or motor deficits associated with the region of the CNS affected. The prevalence of this disease has increased rapidly over the last decade. Despite the approval of many new pharmaceutical therapies in the past 20 years, there remains a growing need for alternative therapies to manage the course of this disease. Treatments are separated into two main categories: management of acute flare versus long-term prevention of flares via disease-modifying therapy. Primary drug therapies for acute flare include corticosteroids to limit inflammation and symptomatic management, depending on symptoms. Several different drugs have been recently approved for use in modifying the course of the disease, including a group of medications known as fumarates (e.g., dimethyl fumarate, diroximel fumarate, monomethyl fumarate) that have been shown to be efficacious and relatively safe. In the present investigation, we review available evidence focused on monomethyl fumarate, also known as Bafiertam®, along with bioequivalent fumarates for the long-term treatment of relapsing-remitting multiple sclerosis.
ABSTRACT
In this paper, in order to address the problem of electron leakage in AlGaN ultra-violet light-emitting diodes, we have proposed an electron-blocking free layer AlGaN ultra-violet (UV) light-emitting diode (LED) using polarization-engineered heart-shaped AlGaN quantum barriers (QB) instead of conventional barriers. This novel structure has decreased the downward band bending at the interconnection between the consecutive quantum barriers and also flattened the electrostatic field. The parameters used during simulation are extracted from the referred experimental data of conventional UV LED. Using the Silvaco Atlas TCAD tool; version 8.18.1.R, we have compared and optimized the optical as well as electrical characteristics of three varying LED structures. Enhancements in electroluminescence at 275 nm (52.7%), optical output power (50.4%), and efficiency (61.3%) are recorded for an EBL-free AlGaN UV LED with heart-shaped Al composition in the barriers. These improvements are attributed to the minimized non-radiative recombination on the surfaces, due to the progressively increasing effective conduction band barrier height, which subsequently enhances the carrier confinement. Hence, the proposed EBL-free AlGaN LED is the potential solution to enhance optical power and produce highly efficient UV emitters.
ABSTRACT
This paper presents alternate pairs of InGaN/GaN prestrained layers with varying indium compositions, which are inserted between the GaN/InGaN MQW active region and the n-GaN layer in a light-emitting diode (LED) nanostructure in order to obtain enhanced optical characteristics. The device is mounted on a silicon substrate followed by a GaN buffer layer that promotes charge injection by minimizing the energy barrier between the electrode and active layers. The designed device attains more than 2.897% enhancement in efficiency when compared with the conventional LED, which is attributed to the reduction of a polarization field within the MQW region. The proposed device with 15% indium composition in the prestrained layer attains a maximum efficiency of 85.21% and a minimized efficiency droop of 3.848% at an injection current of 40 mA, with high luminous power in the output spectral range. The device also shows a minimum blueshift in the spectral range, indicating a decrease in the piezoelectric polarization.