Respiratory oscillations in yeast: mitochondrial reactive oxygen species, apoptosis and time; a hypothesis

Oscillatory metabolic activities occur more widely than is generally realised; detectability requires observation over extended times of single yeast cells or synchrony of individuals to provide a coherent population. Where oscillations in intracellular metabolite concentrations are observed, the phenomenon has been ascribed to sloppy control, energetic optimisation, signalling, temporal compartmentation of incompatible reactions, or timekeeping functions. Here we emphasise the consequences of respiratory oscillations as a source of mitochondrially generated reactive O2 metabolites. Temporal co-ordination of intracellular activities necessitates a time base. This is provided by an ultradian clock, and one result of its long-term operation is cyclic energisation of mitochondria, and thereby the generation of deleterious free radical species. Our hypothesis is that unrepaired cellular constituents and components (especially mitochondria) eventually lead to cellular senescence and apoptosis when a finite number of respiratory cycles has occurred

Connecting Beyond the Classroom: Use of Viber as a Support Tool for Enhancing Essay Writing Skills and Online Language Learning Engagement among Students

This research study discovered students\u27 online English learning engagement through the use of Viber as a support tool in essay writing by the first-year English majors at a university level with a total of ten participants, five women and five men. It employed the Quasi-experimental design, and pre-and post-test design was used to measure the language learning engagement of the first-year students at a tertiary level. Data were analyzed through frequency count and percentage with the help of SPSS. The result shows that student engagement and level of attitude in language class before the utilization of VST is very low. This means they are very upset in the language class, especially in writing. However, after using VST, their attitude towards writing changes, which means that Viber positively impacts their attitude towards writing. It is also found that they are proficient and well-immersed in writing. Based on the pre-test and post-test scores, they may use Viber as a Support tool or opt to use traditional support because this study revealed that their performance in writing remains good for the two interventions. However, teachers may consider the view of students on using Viber, for this gives them greater efficiency in writing because it makes them focus. Teachers may consider incorporating Viber in their teaching methods to enhance their students\u27 writing skills and overall learning experience

Indoor Air Quality Implications of Germicidal 222 nm Light

One strategy for mitigating the indoor transmission of airborne pathogens, including the SARS-CoV-2 virus, is irradiation by germicidal UV light (GUV). A particularly promising approach is 222 nm light from KrCl excimer lamps (GUV222); this inactivates airborne pathogens and is thought to be relatively safe for human skin and eye exposure. However, the impact of GUV222 on the composition of indoor air has received little experimental study. Here, we conduct laboratory experiments in a 150 L Teflon chamber to examine the formation of secondary species by GUV222. We show that GUV222 generates ozone (O3) and hydroxyl radicals (OH), both of which can react with volatile organic compounds to form oxidized volatile organic compounds and secondary organic aerosol particles. Results are consistent with a box model based on the known photochemistry. We use this model to simulate GUV222 irradiation under more realistic indoor air scenarios and demonstrate that under some conditions, GUV222 irradiation can lead to levels of O3, OH, and secondary organic products that are substantially elevated relative to normal indoor conditions. The results suggest that GUV222 should be used at low intensities and in concert with ventilation, decreasing levels of airborne pathogens while mitigating the formation of air pollutants

Examination of the optimal operation of building scale combined heat and power systems under disparate climate and GHG emissions rates

This paper was accepted for publication in the journal Applied Energy and the definitive published version is available at https://doi.org/10.1016/j.apenergy.2016.09.108This work aims to elucidate notions concerning the ideal operation and greenhouse gas (GHG) emissions benefits of combined heat and power (CHP) systems by investigating how various metrics change as a function of the GHG emissions from the underlying electricity source, building use type and climate. Additionally, a new term entitled \CHP Attributable" reductions is introduced to quantify the benefits from the simultaneous use of thermal and electric energy, removing benefits achieved solely from fuel switching and generating electricity more efficiently. The GHG emission benefits from implementing internal combustion engine, microturbines, and phosphoric acid (PA) fuel cell based CHP systems were evaluated through an optimization approach considering energy demands of prototypical hospital, office, and residential buildings in varied climates. To explore the effect of electric GHG emissions rates, the ideal CHP systems were determined under three scenarios: \High" GHG emissions rates, \Low" GHG emissions rates, and \Current" GHG emissions rate for a specific location. The analysis finds that PA fuel cells achieve the highest GHG emission reductions in most cases considered, though there are exceptions. Common heuristics, such as electric load following and thermal load following, are the optimal operating strategy under specific conditions. The optimal CHP capacity and operating hours both vary as a function of building type, climate and GHG emissions rates from grid electricity. GHG emissions reductions can be as high as 49% considering a PA fuel cell for a prototypical hospital in Boulder, Colorado however, the \CHP attributable reductions are less than 10%