Crystallisation of bis(2-hydroxyethylene) terephthalate as a part of a bottle-to-bottle recycling concept for poly(ethylene terephthalate)

The chemical recycling of poly(ethylene terephthalate (PET) is very attractive as PET bottle waste provides an abundant clean material with low levels of additives. One of the most promising processes is glycolysis, which depolymerises PET in the presence of ethylene glycol. For this process, it is necessary to think through the whole concept from the waste material to the newly polymerised virgin polymer. Most research ends with determining the yield of bis(2-hydroxyethyl)terephthalate (BHET) after glycolysis. Some research includes anti-solvent crystallisation with water to separate BHET from ethylene glycol. However, the subsequent separation of water and ethylene glycol is an energy intensive process. Therefore, this work aims at the direct crystallisation of BHET from ethylene glycol. For this reason, the crystallisation of BHET was investigated experimentally. Crystallisation was simulated using gPROMS Formulated Products with aim of estimating kinetic parameters and using these to optimise an industrial process. Kinetic parameters were determined by model validation including primary and secondary nucleation and crystal growth. The best fitting set of kinetic parameters was used to optimise BHET crystallisation in batch and continuous mode by minimising equipment costs. Impeller parameters were found to have a great influence on crystallisation performance. Ultimately, the continuous and batch processes gave comparable results in terms of equipment cost, with the batch process giving larger crystals and higher yields, but the continuous process requiring a smaller crystalliser

Ammonia exposure promotes algal biomass in an ombrotrophic peatland

Nitrogen pollution affects many peatlands with consequences for their biodiversity and ecosystem function. Microorganisms control nutrient cycling and constitute most of the biodiversity of peatlands but their response to nitrogen is poorly characterised and likely to depend on the form of deposition. Using a unique field experiment we show that ammonia exposure at realistic point source levels is associated with a general shift from heterotrophic (bacteria and fungi) to autotrophic (algal) dominance and an increase in total biomass. The biomass of larger testate amoebae increased, suggesting increased food supply for microbial predators. Results show the widespread impacts of N pollution and suggest the potential for microbial community-based bioindicators in these ecosystems

Tick Ecdysteroid Hormone, Global Microbiota/\u3ci\u3eRickettsia\u3c/i\u3e Signaling in the Ovary Versus Carcass During Vitellogenesis in Part-Fed (Virgin) American Dog Ticks, \u3ci\u3eDermacentor variabilis\u3c/i\u3e

The transovarial transmission of tick-borne bacterial pathogens is an important mechanism for their maintenance in natural populations and transmission, causing disease in humans and animals. The mechanism for this transmission and the possible role of tick hormones facilitating this process have never been studied. Injections of physiological levels of the tick hormone, 20-hydroxyecdysone (20E), into part-fed (virgin) adult females of the American dog tick, Dermacentor variabilis, attached to the host caused a reduction in density of Rickettsia montanensis in the carcass and an increase in the ovaries compared to buffer-injected controls. This injection initiates yolk protein synthesis and uptake by the eggs but has no effect on blood feeding. Francisella sp. and R. montanensis were the predominant bacteria based on the proportionality in the carcass and ovary. The total bacteria load increased in the carcass and ovaries, and bacteria in the genus Pseudomonas increased in the carcass after the 20E injection. The mechanism of how the Rickettsia species respond to changes in tick hormonal regulation needs further investigation. Multiple possible mechanisms for the proliferation of R. montanensis in the ovaries are proposed

Annealing schedule from population dynamics

We introduce a dynamical annealing schedule for population-based optimization algorithms with mutation. On the basis of a statistical mechanics formulation of the population dynamics, the mutation rate adapts to a value maximizing expected rewards at each time step. Thereby, the mutation rate is eliminated as a free parameter from the algorithm.Comment: 6 pages RevTeX, 4 figures PostScript; to be published in Phys. Rev.