Biocatalytic Self‐Assembly of Nanostructured Peptide Microparticles using Droplet Microfluidics

Uniformly‐sized, nanostructured peptide microparticles are generated by exploiting the ability of enzymes to serve (i) as catalysts, to control self‐assembly within monodisperse, surfactant‐stabilized water‐in‐oil microdroplets, and (ii) as destabilizers of emulsion interfaces, to enable facile transfer of the produced microparticles to water. This approach combines the advantages of biocatalytic self‐assembly with the compartmentalization properties enabled by droplet microfluidics. Firstly, using microfluidic techniques, precursors of self‐assembling peptide derivatives and enzymes are mixed in the microdroplets which upon catalytic conversion undergo molecular self‐assembly into peptide particles, depending on the chemical nature of the precursors. Due to their amphiphilic nature, enzymes adsorb at the water‐surfactant‐oil interface of the droplets, inducing the transfer of peptide microparticles from the oil to the aqueous phase. Ultimately, through washing steps, enzymes can be removed from the microparticles which results in uniformely‐sized particles composed of nanostructured aromatic peptide amphiphiles.     

Brevetoxin,the Dinoflagellate Neurotoxin,Localizes to Thylakoid Membranes and Interacts with the Light‐Harvesting Complex II (LHCII) of Photosystem II

The brevetoxins are neurotoxins that are produced by the “Florida red tide” dinoflagellate Karenia brevis. They bind to and activate the voltage‐gated sodium channels in higher organisms, specifically the Na_v1.4 and Na_v1.5 channel subtypes. However, the native physiological function that the brevetoxins perform for K. brevis is unknown. By using fluorescent and photoactivatable derivatives, brevetoxin was shown to localize to the chloroplast of K. brevis where it binds to the light‐harvesting complex II (LHCII) and thioredoxin. The LHCII is essential to non‐photochemical quenching (NPQ), whereas thioredoxins are critical to the maintenance of redox homeostasis within the chloroplast and contribute to the scavenging of reactive oxygen. A culture of K. brevis producing low levels of toxin was shown to be deficient in NPQ and produced reactive oxygen species at twice the rate of the toxic culture, implicating a role in NPQ for the brevetoxins.     

The influence of travelling fires on a concrete frame

When building fires occur in large, open compartments they rarely burn uniformly across an entire floor plate of a structure. Instead, they tend to travel, igniting fuel in their path and burning it out as they move to the next fuel package. Current structural fire design methods do not account for these types of fires. This paper applies a novel methodology for defining a family of possible heating regimes to a framed concrete structure using the concept of travelling fires. A finite-element model of a generic concrete structure is used to study the impact of the family of fires; both relative to one another and in comparison to the conventional codified temperature-time curves. It is found that travelling fires have a significant impact on the performance of the structure and that the current design approaches cannot be assumed to be conservative. Further, it is found that a travelling fire of approximately 25% of the floor plate in size is the most severe in terms of structural response. It is concluded that the new approach is simple to implement, provides more realistic fire scenarios, and is more conservative than current design methods.     

Analysis of the Thermomechanical Response of Structural Cables Subject to Fire

Fire Technology - Cable-supported structures such as bridges and stadia are critical for the surrounding community and the consequences arising from a major fire event can be substantial. Previous...     

Measurement of nuclear DNA content in fission yeast by flow cytometry

Cell division cycle (cdc) mutants of Schizosaccharomyces pombe are arrested at specific points in the cell cycle when grown at restrictive temperature. Flow cytometry of such cells reveals an anomalous increase in the DNA fluorescence signal, which represents a problem in experiments designed to determine the cell cycle arrest point. The increased fluorescence signal is due to cytoplasmic constituents and has been attributed to mitochondrial DNA synthesis (S. Sazer and S. W. Sherwood, J. Cell Sci.97: 509–516, 1990). Here we have studied the cdc10 mutant by flow cytometry using different DNA-binding fluorochromes and found no evidence that the increased fluorescence signal was caused by mitochondrial DNA synthesis. To determine more accurately the nuclear DNA content we have developed a novel method to remove most of the cytoplasmic material by exposing the cells to Triton X-100 and hypotonic conditions after cell wall digestion. The DNA fluorescence from cells treated in this way was more constant with time of incubation at restrictive temperature in spite of a considerable increase in cell size. With this method we could determine that the recently isolated temperature sensitive orp1 mutant is arrested with a 1C DNA content. Premature and abnormal mitosis (‘cut’) could be observed for the orp1 mutant after only 4 h at restrictive temperature. © 1997 John Wiley & Sons, Ltd.     

Examining the fire risk in London dwellings using the London Fire Brigade Incident database

Analysis of the Fire Brigade's database of fires in London between 2009 and 2020 provided insight into the level of fire safety in the city and how it varies across different types of dwellings and different levels of protection. Regarding the number of fires, fatalities, and injuries, fire safety in London has significantly improved on average over these years. However, average trends cannot analyze catastrophic fires with multiple fatalities, like at Grenfell Tower in 2017, as these events are too rare to form a suitable sample size. Dwelling fires are the most lethal in London: despite accounting for only 28% of fires, they lead to 87% of fatalities and 83% of injuries. The odds of a dwelling fire becoming fatal in London fell from 1 in 174 in 2009 to 1 in 208 in 2019, a decrease of 16%. The total number of fires has decreased over this period, and the number of fires where an alarm was raised has increased, suggesting that the prevention and detection layers of fire safety have improved, while our analysis suggests that the level of protection from the compartmentation and evacuation layers has remained constant over time. An analysis of the different layers of fire protection suggests that compartmentation was the most impactful layer, with a failure in compartmentation increasing the odds of a fire being fatal by 1.5 to 5 times. Overall, this analysis shows that the fire hazard to Londoners in general is low and the lowest since 2009; however, there is still a threat that should not be understated.