Monitoring water contamination in jet fuel using silica-based Bragg grating refractometry

This work quantifies water contamination in jet fuel (Jet A-1), using silica-based Bragg gratings. The optical sensor geometry exposes the evanescent optical field of a guided mode to enable refractometery. Quantitative analysis is made in addition to the observation of spectral features consistent with emulsification of water droplets and Stokes’ settling. Measurements are observed for cooling and heating cycles between ranges of 22°C and -60°C. The maximum spectral sensitivity for water contamination was 2.4 pm/ppm-v with a resolution of < 5 ppm-v

Continuous ultraviolet to blue-green astrocomb

Broadband UV-green generation is achieved from a 1-GHz Ti:sapphire frequency comb using a Zn-indiffused, grating-engineered MgO:PPLN ridge waveguide. Etalon-filtering produces a 30 GHz astrocomb from 390–480 nm, with modes resolvable by an Echelle-prism spectrograph

Machine learning and metabolic modelling assisted implementation of a novel process analytical technology in cell and gene therapy manufacturing

Abstract Process analytical technology (PAT) has demonstrated huge potential to enable the development of improved biopharmaceutical manufacturing processes by ensuring the reliable provision of quality products. However, the complexities associated with the manufacture of advanced therapy medicinal products have resulted in a slow adoption of PAT tools into industrial bioprocessing operations, particularly in the manufacture of cell and gene therapy products. Here we describe the applicability of a novel refractometry-based PAT system (Ranger system), which was used to monitor the metabolic activity of HEK293T cell cultures during lentiviral vector (LVV) production processes in real time. The PAT system was able to rapidly identify a relationship between bioreactor pH and culture metabolic activity and this was used to devise a pH operating strategy that resulted in a 1.8-fold increase in metabolic activity compared to an unoptimised bioprocess in a minimal number of bioreactor experiments; this was achieved using both pre-programmed and autonomous pH control strategies. The increased metabolic activity of the cultures, achieved via the implementation of the PAT technology, was not associated with increased LVV production. We employed a metabolic modelling strategy to elucidate the relationship between these bioprocess level events and HEK293T cell metabolism. The modelling showed that culturing of HEK293T cells in a low pH (pH 6.40) environment directly impacted the intracellular maintenance of pH and the intracellular availability of oxygen. We provide evidence that the elevated metabolic activity was a response to cope with the stress associated with low pH to maintain the favourable intracellular conditions, rather than being indicative of a superior active state of the HEK293T cell culture resulting in enhanced LVV production. Forecasting strategies were used to construct data models which identified that the novel PAT system not only had a direct relationship with process pH but also with oxygen availability; the interaction and interdependencies between these two parameters had a direct effect on the responses observed at the bioprocess level. We present data which indicate that process control and intervention using this novel refractometry-based PAT system has the potential to facilitate the fine tuning and rapid optimisation of the production environment and enable adaptive process control for enhanced process performance and robustness

Developing zinc-indiffused PPLN ridge waveguides for UV, visible and MIR quantum applications

We have previously reported robust zinc-indiffused MgO:PPLN ridge waveguides for field applications in quantum-enhanced gravimetry and navigation, generating 2.5W of 780nm light at 74% second-harmonic generation (SHG) conversion efficiency. To tailor this process for different wavelengths and interactions, the effect of fabrication parameters on the waveguide mode shape and size from UV to MIR has been studied, with the aim to optimise mode matching between pump, SHG, and optical fibres to improve conversion efficiency, and reduce insertion loss in packaged devices

Developing zinc-indiffused periodically poled lithium niobate ridge waveguides for quantum applications at visible wavelengths

Tailored laser sources at visible range wavelengths are in ever increasing demand as technologies for quantum computing, sensing, and remote imaging continue to evolve. As these technologies start to move out of the labora-tory and into the field, the requirement for compact, efficient, rugged laser sources makes wavelength conversion of established laser systems and diodes an obvious choice