Demonstration of 651†nm InGaN-based red light-emitting diode with an external quantum efficiency over 6% by InGaN/AlN strain release interlayer.

This work reports a high-performance InGaN-based red-emitting LED with a strain-release interlayer (SRI) consisting of an InGaN stress-release layer (SRL) and an AlN dislocation confinement layer (DCL) in unintentionally doped GaN (u-GaN). The SRL introduces a tensile strain which could decrease the in-plane compressive stress of the u-GaN layer, while the DCL could reduce the dislocation density and thus improve the crystal quality of the u-GaN layer. Consequently, a high-efficiency InGaN-based red-emitting LED with a peak wavelength of 651 nm and an external quantum efficiency of 6.04% is realized. In addition, the room-temperature photoluminescence (PL) mapping emission wavelength is uniform across a 4-inch wafer with a standard deviation of 3.3 nm. Therefore, the proposed SRI offers good potential for mass-producing high-performance and long-wavelength InGaN-based red-emitting LEDs.

New-onset tachycardia-bradycardia syndrome following acute non-medullary brainstem infarction.

Tachycardia-bradycardia syndrome (TBS) is a variant of sick sinus syndrome (SSS) characterized by alternating tachycardia and bradycardia. A few cases of SSS secondary to structural lesions in the medulla have been reported, but there has never been a reported case of the rare sign akin to TBS following acute non-medullary brainstem infarction. Furthermore, new-onset cardiac arrhythmias in stroke often presented in one continuous pattern - either as bradycardia or tachycardia, but instances of an alternating fashion have been rarely reported. We present the case of a 46-year-old female who developed severe dizziness with vomiting, diplopia, and slurred speech, which gradually worsened to quadriplegia, severe hypophonia, and dysphagia. Brain magnetic resonance imaging (MRI) demonstrated acute midbrain and pontine infarction. Except for neurological symptoms, the patient experienced unexpected TBS with the symptoms of excessive sweating, palpitations, and irritability without any other predisposing factors. The frequency of the episodes gradually declined until it spontaneously disappeared the 5th day after admission. Given the unpredictable nature of the tachycardia and bradycardia, it was challenging to manage the arrythmias with medications. A pacemaker was recommended, but financial reasons led the patient to reject this option. Two weeks after antithrombotic therapy and rehabilitation, she was discharged with residual symptoms of diplopia, moderate dysarthria, mild quadriplegia, and no cardiac symptoms. Our case highlighted the occurrence of TBS as a new-onset arrhythmia that can manifest during the acute phase of non-medullary brainstem infarcts. Further research into brainstem lesions contributing to TBS is warranted us to elucidate the underlying mechanisms.