A Brief Review of Low-Level Light Therapy in Depression Disorder.

Low-level laser therapy (LLLT), also called Photobiomodulation, has gained widespread acceptance as a mainstream modality, particularly in the form of photobiostimulation (PBM). Here in our review, we aim to present the application of LLLT to help with depression, explore potential action mechanisms and pathways, discuss existing limitations, and address the challenges associated with its clinical implementation. In biological systems, the visible light with a wavelength range of 400-700 nm activates photoreceptors involved in vision and circadian rhythm regulation.

Photodegradation mechanisms of reactive blue 19 dye under UV and simulated solar light irradiation.

In this work we performed dye photodegradation experiments in presence of TiO and Cu/Zr modified TiO. The changes in the shape of the spectra of RB19 caused by photocatalysts under the simulated solar or UV light were monitored. Since the predominant photocatalytic mechanism can only be observed in very dilute solution of RB19, UV-Vis absorption spectrometry for higher concentrations and thermal lens spectrometry for lower concentrations have been applied to elucidate the mechanistic details of degradation processes.

Trace detection and photothermal spectral characterization by a tuneable thermal lens spectrometer with white-light excitation.

In the thermal lens experimental set-up we replaced the commonly employed pump laser by a halogen lamp, combined with an interference filter, providing a tuneable, nearly monochromatic pump source over the range of wavelengths 430-710 nm. Counter-propagating pump and probe beams are used and a 1 mm path-length sample cell together with the interference filter makes an optical cavity, providing amplification of the thermal lens signal, which leads to enhancement of the measurement sensitivity, and enables detection of absorbances on the order of 5 × 10. Amplified thermal lens signal allows us to replace the typical lock-in amplifier and digital oscilloscope with a silicon photodetector, Arduino, and a personal computer, offering the possibility for a compact, robust and portable device, useful for in-field absorption measurements in low concentration or weakly absorbing species.