Adsorption of pharmaceuticals on anatase nanoparticles determines the rate and intermediates formed during photodegradation.

The rates of decomposition of solutions of benzoyl peroxide in carbon tetrachloride have been measured at temperatures of 60" C and 70" C in the pressure range 0 to 3000 kg/cm2. The results show that the decomposition at high pressures has the same mechanism as at atmospheric pressure and consists of a unimolecular decomposition into free radicals accompanied by a radical-induced chain decomposition. The effect of pressure is to decrease the rate of the unimolecular decomposition but to increase the rate of the chain decomposition.It is concluded that the effect of pressure on the rate of initiation in the peroxidecatalyzed polymerization of styrene is small and not an important factor in the large increase observed in the rate of polymerization.

With the characterisations of potentially habitable planetary atmospheres on the horizon, the search for biosignatures is set to become a major area of research in the coming decades. To understand the atmospheric characteristics that might indicate alien life we must understand the abiotic characteristics of a planet and how life interacts with its environment. In the field of biogeochemistry, sophisticated models of life-environment coupled systems demonstrate that many assumptions specific to Earth-based life, e.g. specific ATP maintenance costs, are unnecessary to accurately model a biosphere. We explore a simple model of a single-species microbial biosphere that produces 𝐶𝐻 4 as a byproduct of the microbes' energy extraction -known as a type I biosignature. We demonstrate that although significantly changing the biological parameters has a large impact on the biosphere's total population, such changes have only a minimal impact on the strength of the resulting biosignature, while the biosphere is limited by 𝐻 2 availability. We extend the model to include more accurate microbial energy harvesting and show that adjusting microbe parameters can lead to a regime change where the biosphere becomes limited by energy availability and no longer fully exploits the available 𝐻 2 , impacting the strength of the resulting biosignature. We demonstrate that, for a nutrient limited biosphere, identifying the limiting nutrient, understanding the abiotic processes that control its abundance, and determining the biospheres ability to exploit it, are more fundamental for making type I biosignature predictions than the details of the population dynamics of the biosphere.