Pathogen recognition receptors (PRRs) are a class of germ line-encoded receptors that recognize pathogen-associated molecular patterns (PAMPs). The activation of PRRs is crucial for the initiation of innate immunity, which plays a key role in first-line defense until more specific adaptive immunity is developed. PRRs differ in the signaling cascades and host responses activated by their engagement and in their tissue distribution. Currently identified PRR families are the Toll-like receptors (TLRs), the C-type lectin receptors (CLRs), the nucleotide-binding oligomerization domain-like receptors (NLRs), the retinoic acid-inducible gene-I-like receptors (RLRs), and the AIM2-like receptor (ALR). The environment of the dental pulp is substantially different from that of other tissues of the body. Dental pulp resides in a low compliance root canal system that limits the expansion of pulpal tissues during inflammatory processes. An understanding of the PRRs in dental pulp is important for immunomodulation and hence for developing therapeutic targets in the field of endodontics. Here we comprehensively review recent finding on the PRRs and the mechanisms by which innate immunity is activated. We focus on the PRRs expressed on dental pulp and periapical tissues and their role in dental pulp inflammation.

For realizing next-generation solid-state lighting devices, performance breakthroughs must be accomplished for nitride-based light-emitting diodes (LEDs). Highly transparent conductive electrodes (TCEs) may be key to achieving this goal, as they provide uniform current injection and distribution across a large device area, eventually increasing the light output power. However, the trade-off between electrical conductivity and optical transmittance of LEDs must be addressed. Herein, we introduce a novel strategy based on TCEs fabricated using wide-bandgap (WB) materials such as SiNx, incorporated beneath the n-type electrode of vertical-type LEDs, and show the feasibility of this strategy. We employ a novel electrical breakdown (EBD) technique to form conductive filaments (or current paths) between a TCE and n-GaN (GaN: gallium nitride). By employing the EBD process, we obtain both ohmic behavior for SiNx TCE/n-GaN and a current spreading effect across n-GaN. These results demonstrate the tremendous potential of WB-TCEs for use in high-performance optoelectronic devices.

Deep‐ultraviolet light‐emitting diodes (DUV‐LEDs) find widespread applications in various industries and are a focus area in environmental and life science research. However, the quantum efficiency of DUV‐LEDs is still low because of the unbalanced hole injection, high operation voltage, and low reflectivity of the p‐electrode. In this study, a smart wide‐bandgap omnidirectional reflector (ODR), which simultaneously acts as an effective hole‐injection electrode, is demonstrated for a flip‐chip DUV‐LED. The smart ODR is composed of p‐type AlGaN (p‐AlGaN)/Ni:AlN/Al with a high reflectivity of 94.2% at 280 nm, in which AlN with a theoretically calculated thickness of 40 nm is Ni‐doped using the pulsed electrical breakdown (PEBD) method. The smart ODR‐mounted AlGaN‐multiquantum‐well‐based DUV‐LED exhibits a remarkable wall‐plug efficiency (4.8%) and high external quantum efficiency (8.5%) at a low operation voltage of 9.75 V owing to the fused layer of Ni3N and Ga vacancies formed in the interfacial region of the p‐AlGaN and AlN layers, through the mutual diffusion of Ni and Ga during PEBD. The interface‐mediated Ohmic contact leads to an effective hole injection without reducing the reflectivity, yielding increased optical output and electric input powers. The proposed smart ODR can provide an innovative route for the manipulation of DUV light.

We report the enhancement of deep ultraviolet emissions from AlGaN-based quantum wells (QWs) using energy-matched localized surface plasmons (LSPs) in platinum (Pt) nanoring arrays. The peak resonances of the extinction spectra were shifted to the red spectral region as the nanoring diameters increased, and the Pt nanorings with a diameter of 325 nm exhibited strong photoluminescence (PL) resonance at 279 nm. The emission enhancement ratio was calculated to be 304% in peak PL intensity when compared to that of the bare AlGaN QWs; this is attributed to the strong coupling of QWs with LSPs from the Pt nanorings.