Spectroscopy

This article is from earlier in the year but I missed until now!

Abstract

The emergence of Batrachochytrium salamandrivorans (Bsal) poses an imminent threat to caudate biodiversity worldwide, particularly through anthropogenic-mediated means such as the pet trade. Bsal is a fungal panzootic that has yet to reach the Americas, Africa, and Australia, presenting a significant biosecurity risk to naïve amphibian populations lacking the innate immune defenses necessary for combating invasive pathogens. We explored the capability of near-infrared spectroscopy (NIRS) coupled with predictive modeling as a rapid, non-invasive Bsal screening tool in live caudates. Using eastern newts (Notopthalmus viridescens) as a model species, NIR spectra were collected in tandem with dermal swabs used for confirmatory qPCR analysis. We identified that spectral profiles differed significantly by physical location (chin, cloaca, tail, and foot) as well as by Bsal pathogen status (control vs. exposed individuals; p < 0.05). The support vector machine algorithm achieved a mean classification accuracy of 80% and a sensitivity of 92% for discriminating Bsal-control (-) from Bsal-exposed (+) individuals. This approach offers a promising method for identifying Bsal-compromised populations, potentially aiding in early detection and mitigation efforts alongside existing techniques.

Abstract: Miniaturization of mid-infrared (MIR) spectroscopy sources has progressed signifi- cantly during the past two decades, but a solution able to provide full integration, high optical power and wide tuneability in the so-called atmospheric window (2.5 - 5 μm) is still missing. In this context, we investigated a broadband frequency-tuneable source relying on difference frequency generation (DFG) in a periodically poled lithium niobate (PPLN) ridge waveguide. By employing tuneable lasers for the pump and signal wavelengths emitting at around 1 μm and 1.55 μm, respectively, we were able to fully cover the ≈ 3 - 3.5 μm spectrum, thus translating the technological maturity of data communication photonic sources to the MIR wavelength band.

Moreover, the use of a relatively large cross-section for the here proposed PPLN ridge waveguide compared to commonly employed thin-film lithium niobate (TFLN) waveguides has allowed us to achieve low propagation and coupling losses together with high damage threshold, thereby allowing us to reach mW-level power in the MIR wavelength band.

cross-posted from: https://sh.itjust.works/post/21614029

One of the OG YouTube chemists dabbles in some radiochemistry and spectroscopy.

PDF Link: https://arxiv.org/pdf/2312.12548.pdf

Deuterium UV lamp for my DIY absorption spectrometer.

Took this photo today and I thought it looked pretty cool, so I wanted to share!

Nature chemistry link: https://www.nature.com/articles/s41557-023-01300-3