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1. Effects of Temperature and p CO ₂ on Population Regulation of Symbiodinium spp. in a Tropical Reef Coral

   https://doi.org/10.1086/692718  

   Baghdasarian, Garen; Osberg, Andrew; Mihora, Danielle; Putnam, Hollie; Gates, Ruth D.; Edmunds, Peter J. (April 2017, The Biological Bulletin)
2. Shallow coral reef free ocean carbon enrichment: Novel in situ flumes to manipulate pCO ₂ on shallow tropical coral reef communities

   https://doi.org/10.1002/lom3.10349  

   Srednick, Griffin; Bergman, Jessica L.; Doo, Steve S.; Hawthorn, Myron; Ferree, Jeffrey; Rojas, Roberto; Arias, Rogelio; Edmunds, Peter J.; Carpenter, Robert C. (February 2020, Limnology and Oceanography: Methods)

   Abstract Given the severe implications of climate change and ocean acidification (OA) for marine ecosystems, there is an urgent need to quantify ecosystem function in present‐day conditions to determine the impacts of future changes in environmental conditions. For tropical coral reefs that are acutely threatened by these effects, the metabolism of benthic communities provides several metrics suitable for this purpose, but the application of infrastructure to manipulate conditions and measure community responses is not fully realized. To date, most studies of the effects of OA on coral reefs have been conducted ex situ, and while greater ecological relevance can be achieved through free ocean carbon enrichment (FOCE) experiments on undisturbed areas of reef, such approaches have been deterred by technical challenges (e.g., spatial scale and duration, stable maintenance of conditions). In this study, we describe novel experimental infrastructure called shallow coral reef (SCoRe) FOCE to overcome these challenges and present data from a proof of concept application in Mo'orea, French Polynesia. Our objectives were to (1) implement an autonomous system that could be deployed kilometers from shore, (2) regulate the chemical (pCO₂) and physical properties of seawater over undisturbed, shallow (∼2–5‐m depth) coral reef over multiple weeks, and (3) measure the metabolic response of the coral community to the treatment conditions. We describe the design, function, and application of the SCoRe FOCE, and present data demonstrating its efficacy. This infrastructure has great potential for advancing ecologically relevant studies of the effects of changing environmental conditions on coral reefs. 

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3. Synthesis and crystallographic characterization of diphenylamide rare-earth metal complexes Ln (NPh ₂ ) ₃ (THF) ₂ and [(Ph ₂ N) ₂ Ln (μ-NPh ₂ )] ₂

   https://doi.org/10.1107/S2056989020009998  

   Palumbo, Chad T.; Kotyk, Christopher M.; Ziller, Joseph W.; Evans, William J. (September 2020, Acta Crystallographica Section E Crystallographic Communications)

   null (Ed.)

   Studies of the coordination chemistry between the diphenylamide ligand, NPh 2 , and the smaller rare-earth Ln III ions, Ln = Y, Dy, and Er, led to the structural characterization by single-crystal X-ray diffraction crystallography of both solvated and unsolvated complexes, namely, tris(diphenylamido-κ N )bis(tetrahydrofuran-κ O )yttrium(III), Y(NPh 2 ) 3 (THF) 2 or [Y(C 12 H 10 N) 3 (C 4 H 8 O) 2 ], 1-Y , and the erbium(III) (Er), 1-Er , analogue, and bis[μ-1κ N :2(η 6 )-diphenylamido]bis[bis(diphenylamido-κ N )yttrium(III)], [(Ph 2 N) 2 Y(μ-NPh 2 )] 2 or [Y 2 (C 12 H 10 N) 6 ], 2-Y , and the dysprosium(III) (Dy), 2-Dy , analogue. The THF ligands of 1-Er are modeled with disorder across two positions with occupancies of 0.627 (12):0.323 (12) and 0.633 (7):0.367 (7). Also structurally characterized was the tetrametallic Er III bridging oxide hydrolysis product, bis(μ-diphenylamido-κ 2 N : N )bis[μ-1κ N :2(η 6 )-diphenylamido]tetrakis(diphenylamido-κ N )di-μ 3 -oxido-tetraerbium(III) benzene disolvate, {[(Ph 2 N)Er(μ-NPh 2 )] 4 (μ-O) 2 }·(C 6 H 6 ) 2 or [Er 4 (C 12 H 10 N) 8 O 2 ]·2C 6 H 6 , 3-Er . The 3-Er structure was refined as a three-component twin with occupancies 0.7375:0.2010:0.0615. 

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4. pH, Nanosheet Concentration, and Antioxidant Affect the Oxidation of Ti ₃ C ₂ T _x and Ti ₂ CT _x MXene Dispersions

   https://doi.org/10.1002/admi.202000845  

   Zhao, Xiaofei; Vashisth, Aniruddh; Blivin, Jackson_W; Tan, Zeyi; Holta, Dustin_E; Kotasthane, Vrushali; Shah, Smit_A; Habib, Touseef; Liu, Shuhao; Lutkenhaus, Jodie_L; et al (August 2020, Advanced Materials Interfaces)

   Abstract The chemical stability of 2D MXene nanosheets in aqueous dispersions must be maintained to foster their widespread application. MXene nanosheets react with water, which results in the degradation of their 2D structure into oxides and carbon residues. The latter detrimentally restricts the shelf life of MXene dispersions and devices. However, the mechanism of MXene degradation in aqueous environment has yet to be fully understood. In this work, the oxidation kinetics is investigated of Ti₃C₂T_xand Ti₂CT_xin aqueous media as a function of initial pH values, ionic strengths, and nanosheet concentrations. The pH value of the dispersion is found to change with time as a result of MXene oxidation. Specifically, MXene oxidation is accelerated in basic media by their reaction with hydroxyl anions. It is also demonstrated that oxidation kinetics are strongly dependent on nanosheet dispersion concentration, in which oxidation is accelerated for lower MXene concentrations. Ionic strength does not strongly affect MXene oxidation. The authors also report that citric acid acts as an effective antioxidant and mitigates the oxidation of both Ti₃C₂T_xand Ti₂CT_xMXenes. Reactive molecular dynamic simulations suggest that citric acid associates with the nanosheet edge to hinder the initiation of oxidation. 

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5. Daily variation in net primary production and net calcification in coral reef communities exposed to elevated <i>p</i>CO₂

   https://doi.org/10.5194/bg-14-3549-2017  

   Comeau, Steeve; Edmunds, Peter J.; Lantz, Coulson A.; Carpenter, Robert C. (January 2017, Biogeosciences)

   The threat represented by ocean acidification (OA) for coral reefs has received considerable attention because of the sensitivity of calcifiers to changing seawater carbonate chemistry. However, most studies have focused on the organismic response of calcification to OA, and only a few have addressed community-level effects, or investigated parameters other than calcification, such as photosynthesis. Light (photosynthetically active radiation, PAR) is a driver of biological processes on coral reefs, and the possibility that these processes might be perturbed by OA has important implications for community function. Here we investigate how CO₂ enrichment affects the relationships between PAR and community net O₂ production (P_net), and between PAR and community net calcification (G_net), using experiments on three coral communities constructed to match (i) the back reef of Mo'orea, French Polynesia, (ii) the fore reef of Mo'orea, and (iii) the back reef of O'ahu, Hawaii. The results were used to test the hypothesis that OA affects the relationship between P_net and G_net. For the three communities tested, pCO₂ did not affect the P_net–PAR relationship, but it affected the intercept of the hyperbolic tangent curve fitting the G_net–PAR relationship for both reef communities in Mo'orea (but not in O'ahu). For the three communities, the slopes of the linear relationships between P_net and G_net were not affected by OA, although the intercepts were depressed by the inhibitory effect of high pCO₂ on G_net. Our result indicates that OA can modify the balance between net calcification and net photosynthesis of reef communities by depressing community calcification, but without affecting community photosynthesis. 

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