Continuous-wave second-harmonic generation in the far-UVC pumped by a blue laser diode.

Far-UVC light in the wavelength range of 200-230 nm has attracted renewed interest because of its safety for human exposure and effectiveness in inactivating pathogens. Here we present a compact solid-state far-UVC laser source based on second-harmonic generation (SHG) using a low-cost commercially-available blue laser diode pump. Leveraging the high intensity of light in a nanophotonic waveguide and heterogeneous integration, our approach achieves Cherenkov phase-matching across a bonded interface consisting of a silicon nitride (SiN) waveguide and a beta barium borate (BBO) nonlinear crystal. Through systematic investigations of waveguide dimensions and pump power, we analyze the dependencies of Cherenkov emission angle, conversion efficiency, and output power. Experimental results confirm the feasibility of generating far-UVC, paving the way for mass production in a compact form factor. This solid-state far-UVC laser source shows significant potential for applications in human-safe disinfection, non-line-of-sight free-space communication, and deep-UV Raman spectroscopy.

Lysyl Oxidase Regulates Epithelial Differentiation and Barrier Integrity in Eosinophilic Esophagitis.

BACKGROUND & AIMS: Epithelial disruption in eosinophilic esophagitis (EoE) encompasses both impaired differentiation and diminished barrier integrity. We have shown that lysyl oxidase (LOX), a collagen cross-linking enzyme, is up-regulated in the esophageal epithelium in EoE. However, the functional roles of LOX in the esophageal epithelium remains unknown. METHODS: We investigated roles for LOX in the human esophageal epithelium using 3-dimensional organoid and air-liquid interface cultures stimulated with interleukin (IL)13 to recapitulate the EoE inflammatory milieu, followed by single-cell RNA sequencing, quantitative reverse-transcription polymerase chain reaction, Western blot, histology, and functional analyses of barrier integrity. RESULTS: Single-cell RNA sequencing analysis on patient-derived organoids revealed that LOX was induced by IL13 in differentiated cells. LOX-overexpressing organoids showed suppressed basal and up-regulated differentiation markers. In addition, LOX overexpression enhanced junctional protein genes and transepithelial electrical resistance. LOX overexpression restored the impaired differentiation and barrier function, including in the setting of IL13 stimulation. Transcriptome analyses on LOX-overexpressing organoids identified an enriched bone morphogenetic protein (BMP) signaling pathway compared with wild-type organoids. In particular, LOX overexpression increased BMP2 and decreased the BMP antagonist follistatin. Finally, we found that BMP2 treatment restored the balance of basal and differentiated cells. CONCLUSIONS: Our data support a model whereby LOX exhibits noncanonical roles as a signaling molecule important for epithelial homeostasis in the setting of inflammation via activation of the BMP pathway in the esophagus. The LOX/BMP axis may be integral in esophageal epithelial differentiation and a promising target for future therapies.

Influence of Helium-Neon laser photostimulation on excision wound healing in Wistar rats.

The importance of laser photostimulation is now accepted generally but the laser light facilitates wound healing and tissue repair remains poorly understood. So we have examined the hypothesis that the laser photo stimulation can enhances the collagen production in excision wounds using excision wound model in Wister rat model. The circular wounds were created on the dorsum of the back of the animals. The animals were divided into two groups. The experimental group (n = 12) wound was treated with 632.8 nm He-Ne laser at a dose of 2.1J cmƒ{2 for five days a week until the complete healing. The control group was sham irradiated. The parameters studied were wound area, period of epithelization and hydroxyproline. Significant increase in the hydroxyproline content (p<0.001) and reduction in the wound size (p<0.001) was observed in study group when compared to controls. The significant epithelization (p<0.001) was noticed. The experimental wounds were, on average, fully healed by the 15th day, whereas the control group healed, on average by 22nd day. Wound contraction together with the hydroxyproline and experimental observations suggested that low intensity Helium-Neon laser photo stimulation facilitates the tissue repair process by accelerating collagen production in chronic wounds.