Photobioreactor Limnospira indica Growth Model: Application From the MELiSSA Plant Pilot Scale to ISS Flight Experiment

Bioregenerative life support systems (BLSS) are the foundation stone to self-sustainable manned space missions. The MELiSSA is a BLSS concept that has evolved through a mechanistic engineering approach designed to acquire both theoretical and technical knowledge on each subsystem independently and, therefore, produces the necessary knowledge and experience needed to co-integrate all the subsystems together with a high level of control. One of the subsystems is a photobioreactor colonized by an axenic culture of the cyanobacterium Limnospira indica PCC8005 for revitalizing the air for the crew. This subsystem was extensively studied, and a mass balanced mechanistic model was developed to describe, predict, and control the photobioreactor. The model was based on a light transfer limitation model coupled to a kinetic model for the cyanobacteria growth through a Linear Thermodynamics of Irreversible Processes (LTIP) approach, including substrate limitation. The model was integrated into several hydrodynamic models adapted to several photobioreactors design and experiments, from a 100 L airlift pilot scale ground photobioreactor to a 50 ml membrane photobioreactor for ISS flight. Through this article we detail the principles of this mechanistic model and their application to different photobioreactor scales for predictive and descriptive simulations.

Electron Transfer from Semiconductor Nanocrystals to Redox Enzymes

This review summarizes progress in understanding electron transfer from photoexcited nanocrystals to redox enzymes. The combination of the light-harvesting properties of nanocrystals and the catalytic properties of redox enzymes has emerged as a versatile platform to drive a variety of enzyme-catalyzed reactions with light. Transfer of a photoexcited charge from a nanocrystal to an enzyme is a critical first step for these reactions. This process has been studied in depth in systems that combine Cd-chalcogenide nanocrystals with hydrogenases. The two components can be assembled in close proximity to enable direct interfacial electron transfer or integrated with redox mediators to transport charges. Time-resolved spectroscopy and kinetic modeling have been used to measure the rates and efficiencies of the electron transfer. Electron transfer has been described within the framework of Marcus theory, providing insights into the factors that can be used to control the photochemical activity of these biohybrid systems. The range of potential applications and reactions that can be achieved using nanocrystal–enzyme systems is expanding, and numerous fundamental and practical questions remain to be addressed.

Температурно-зависимое интегральное поглощение экситонных поляритонов в полупроводниковых кристаллах

This paper highlights the temperature factor in the experimental study of total absorption as a method for experimental validation and the study of the exciton–polariton light transfer mechanism near the fundamental absorption edge in semiconductor crystals with spatial dispersion. The results of experimental studies of temperature-dependent total exciton absorption are generalized. The experimentally determined critical temperatures above which total absorption becomes constant, the corresponding critical damping parameter, and longitudinal–transverse splittings for the studied semiconductors CdTe, GaAs, InP, ZnSe, and ZnTe are presented.