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Full-Text Articles in Physical Sciences and Mathematics
Hysteresis Between Coral Reef Calcification And The Seawater Aragonite Saturation State, Ashly Mcmahon, Isaac R. Santos, Tyler Cyronak, Bradley D. Eyre
Hysteresis Between Coral Reef Calcification And The Seawater Aragonite Saturation State, Ashly Mcmahon, Isaac R. Santos, Tyler Cyronak, Bradley D. Eyre
Tyler Cyronak
Some predictions of how ocean acidification (OA) will affect coral reefs assume a linear functional relationship between the ambient seawater aragonite saturation state (Ωa) and net ecosystem calcification (NEC). We quantified NEC in a healthy coral reef lagoon in the Great Barrier Reef during different times of the day. Our observations revealed a diel hysteresis pattern in the NEC versus Ωa relationship, with peak NEC rates occurring before the Ωa peak and relatively steady nighttime NEC in spite of variable Ωa. Net ecosystem production had stronger correlations with NEC than light, temperature, nutrients, pH, …
Enhanced Acidification Of Global Coral Reefs Driven By Regional Biogeochemical Feedbacks, Tyler Cyronak, Kai G. Schulz, Isaac R. Santos, Bradley D. Eyre
Enhanced Acidification Of Global Coral Reefs Driven By Regional Biogeochemical Feedbacks, Tyler Cyronak, Kai G. Schulz, Isaac R. Santos, Bradley D. Eyre
Tyler Cyronak
Physical uptake of anthropogenic CO2 is the dominant driver of ocean acidification (OA) in the open ocean. Due to expected decreases in calcification and increased dissolution of CaCO3 framework, coral reefs are thought to be highly susceptible to OA. However, biogeochemical processes can influence the pCO2 and pH of coastal ecosystems on diel and seasonal time scales, potentially modifying the long‐term effects of increasing atmospheric CO2. By compiling data from the literature and removing the effects of short‐term variability, we show that the average pCO2 of coral reefs throughout the globe has increased ~3.5‐fold …
Thermal Removal Of Carbon Dioxide From The Atmosphere: Energy Requirements And Scaling Issues, Ted Von Hippel
Thermal Removal Of Carbon Dioxide From The Atmosphere: Energy Requirements And Scaling Issues, Ted Von Hippel
Ted von Hippel
I conduct a systems-level study of direct air capture of CO2 using techniques from thermal physics. This system relies on a combination of an efficient heat exchanger, radiative cooling, and refrigeration, all at industrial scale and operated in environments at low ambient temperatures. While technological developments will be required for such a system to operate efficiently, those developments rest on a long history of refrigeration expertise and technology, and they can be developed and tested at modest scale. I estimate that the energy required to remove CO2 via this approach is comparable to direct air capture by other techniques. The …
New Technique Of Stereolithography To Local Curing In Thermosensitive Resins Using Co(2) Laser, A. L.J. Munhoz, P. R.S. Wagner, M. C.F. Ierardi, A. E. Kiel, M. A.F. Scarparo, S. D. Allen
New Technique Of Stereolithography To Local Curing In Thermosensitive Resins Using Co(2) Laser, A. L.J. Munhoz, P. R.S. Wagner, M. C.F. Ierardi, A. E. Kiel, M. A.F. Scarparo, S. D. Allen
Susan D. Allen
A theoretical and experimental study of thermosensitive resins used in thermal stereolithography is presented. The process of local curing through the application of infrared radiation, which has proved to be useful in a new technique for the making of prototypes by means of selective heating with C02 laser (10.6um), is studied. The ideal composition of the thermosensitive resins has proved to be 10 parts epoxy, 1.4 part diethylene triamine (the curing agent) and 0.7 part silica powder. A physical theoretical model is applied for control of the parameters which influence the confinement of the curing in the irradiated bulk. A …