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1. Doping of Hollow Urchin-like MnO2 Nanoparticles in Beta-Tricalcium Phosphate Scaffold Promotes Stem Cell Osteogenic Differentiation

   https://doi.org/10.3390/ijms26115092  

   Qian, Enze; Eltawila, Ahmed; Kang, Yunqing (June 2025, International Journal of Molecular Sciences)

   Effective osteogenesis for bone regeneration is still considerably challenging for a porous β-tricalcium phosphate (β-TCP) scaffold to achieve. To overcome this challenge, hollow manganese dioxide (H-MnO2) nanoparticles with an urchin-like shell structure were prepared and added in the porous β-TCP scaffold. A template-casting method was used to prepare the porous H-MnO2/β-TCP scaffolds. As a control, solid manganese dioxide (S-MnO2) nanoparticles were also added into β-TCP scaffolds. Human bone mesenchymal stem cells (hBMSC) were seeded in the porous scaffolds and characterized through cell viability assay and alkaline phosphatase (ALP) assay. Results from in vitro protein loading and releasing experiments showed that H-MnO2 can load significantly higher proteins and release more proteins compared to S-MnO2 nanoparticles. When they were doped into β-TCP, MnO2 nanoparticles did not significantly change the surface wettability and mechanical properties of porous β-TCP scaffolds. In vitro cell viability results showed that MnO2 nanoparticles promoted cell proliferation in a low dose, but inhibited cell growth when the added concentration went beyond 0.5%. At a range of lower than 0.5%, H-MnO2 doped β-TCP scaffolds promoted the early osteogenesis of hBMSCs. These results suggested that H-MnO2 in the porous β-TCP scaffold has promising potential to stimulate osteogenesis. More studies would be performed to demonstrate the other functions of urchin-like H-MnO2 nanoparticles in the porous β-TCP. 

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2. Intercomparison of fast airborne ozone instruments to measure eddy covariance fluxes: spatial variability in deposition at the ocean surface and evidence for cloud processing

   https://doi.org/10.5194/amt-17-5731-2024  

   Chiu, Randall; Obersteiner, Florian; Franchin, Alessandro; Campos, Teresa; Bailey, Adriana; Webster, Christopher; Zahn, Andreas; Volkamer, Rainer (January 2024, Atmospheric Measurement Techniques)

   Abstract. The air–sea exchange of ozone (O3) is controlled by chemistry involving halogens, dissolved organic carbon, and sulfur in the sea surface microlayer. Calculations also indicate faster ozone photolysis at aqueous surfaces, but the role of clouds as an ozone sink is currently not well established. Fast-response ozone sensors offer opportunities to measure eddy covariance (EC) ozone fluxes in the marine boundary layer. However, intercomparisons of fast airborne O3 sensors and EC O3 fluxes measured on aircraft have not been conducted before. In April 2022, the Technological Innovation Into Iodine and GV Environmental Research (TI3GER) field campaign deployed three fast ozone sensors (gas chemiluminescence and a combination of UV absorption with coumarin chemiluminescence detection, CID) together with a fast water vapor sensor and anemometer to study iodine chemistry in the troposphere and stratosphere over Colorado and over the Pacific Ocean near Hawaii and Alaska. Here, we present an instrument comparison between the NCAR Fast O3 instrument (FO3, gas-phase CID) and two KIT Fast AIRborne Ozone instruments (FAIRO, UV absorption and coumarin CID). The sensors have comparable precision < 0.4 % Hz−0.5 (0.15 ppbv Hz−0.5), and ozone volume mixing ratios (VMRs) generally agreed within 2 % over a wide range of environmental conditions: 10 < O3 < 1000 ppbv, below detection < NOx < 7 ppbv, and 2 ppmv < H2O < 4 % VMR. Both instrument designs are demonstrated to be suitable for EC flux measurements and were able to detect O3 fluxes with exchange velocities (defined as positive for upward) as slow as −0.010 ± 0.004 cm s−1, which is in the lower range of previously reported measurements. Additionally, we present two case studies. In one, the direction of ozone and water vapor fluxes was reversed (vO3 = +0.134 ± 0.005 cm s−1), suggesting that overhead evaporating clouds could be a strong ozone sink. Further work is needed to better understand the role of clouds as a possibly widespread sink of ozone in the remote marine boundary layer. In the second case study, vO3 values are negative (varying by a factor of 6–10 from −0.036 ± 0.006 to −0.003 ± 0.004 cm s−1), while the water vapor fluxes are consistently positive due to evaporation from the ocean surface and spatially homogeneous. This case study demonstrates that the processes governing ozone and water vapor fluxes can become decoupled and illustrates the need to elucidate possible drivers (physical, chemical, or biological) of the variability in ozone exchange velocities on fine spatial scales (∼ 20 km) over remote oceans. 

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3. A case study of tensions in student-faculty partnerships for departmental change work

   https://doi.org/10.1119/perc.2023.pr.Abdurrahman  

   Abdurrahman, Fatima N; Sachmpazidi, Diana; Dalka, Robert P; Turpen, Chandra (October 2023, American Association of Physics Teachers)

   Students as Partners (SaP) is a pedagogical approach that considers students co-creators of an educational environment along with faculty, rather than passive participants. While an increasing body of literature evidences a multitude of positive outcomes from the SaP approach, there remains limited research on the challenges that arise in such collaborations. Quan et al. (2021) outlined such challenges in a paper showing that different members of a Departmental Action Team (DAT), in which students, staff, and faculty collaborate on a change effort, had different perspectives of their partnership. In this work, we confirm and expand upon those findings in a case study of another DAT. Our case study DAT comes from the first cohort of the Departmental Action Leadership Institute (DALI), a workshop series that supports faculty members in physics departments facing major challenges or opportunities. We find that all points of disconnect from Quan et al. are present in our case study. Additionally, we identify three specific areas of differing perspectives between faculty and students: motivation, commitment duration, and information transparency. We present evidence of these tensions with interviews from faculty, student, and alumni DAT members. Finally, we discuss how these tensions may be navigated by faculty seeking to partner with students in departmental change work. 

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4. Greenhouse gas flux measurements at the zero curtain, North Slope, Alaska, 2012-2021

   https://doi.org/10.18739/A2ZG6G80B  

   Zona, Donatella (January 2021, NSF Arctic Data Center)

   Climate change is affecting the Arctic at an unprecedented rate, potentially releasing substantial amounts of greenhouse gases (CO2 (carbon dioxide) and CH4 (Methane)) from tundra ecosystems. Measuring greenhouse gas emissions in the Arctic, particularly outside of the summer period, is very challenging due to extreme weather conditions. This research project provided the first annual balance of both CH4 and CO2 fluxes in a total of five sites spanning a 300Km transect across the North Slope of Alaska (three sites in Barrow, one site in Aquasuk, and one site in Ivotuk). The results from the continuous year-round CH4 fluxes across these sites showed how cumulative emissions for the cold season accounted on average for 50% of the annual budget (Zona et al., 2016), a notably higher contribution than previously modelled, and also higher than observed in boreal Alaska. The analysis of the cold period CH4 fluxes suggested that the presence of an unfrozen soil layer in the fall and early winter was a major control on cold season CH4 emissions (Zona et al., 2016). We also cross-compared all instruments measuring ecosystem scale CO2 and CH4 fluxes operating at our sites, which allowed us to make recommendation of the best performing instruments under these extreme weather conditions. The best performing instruments were closed path analyzers and intermittently heated sonic anemometers which had the highest final data cover. A continuously heated anemometer increased data coverage relative to non-heated anemometers, but resulted in an overestimation of the fluxes (Goodrich et al., 2016). We developed an intermittent heating strategy that was only activated when the data quality was low, and appeared to be the preferable method to prevent icing while avoiding biases to the measurements. Closed and open-path analyzers showed good agreement, but data coverage was much greater when using closed-path analyzers, especially during winter (Goodrich et al., 2016). Given the importance of vegetation on greenhouse gas emissions, we also investigated the role of different vegetation types under a broad range of environmental conditions on the CH4 emissions. We found that vegetation type can be a very useful tool to describe the spatial variability in CH4 emissions over the landscape (McEwing et al., 2015), and that just two vegetation types were able to explain about 50% of the variability in CH4 fluxes across ecosystems even hundreds of kilometers apart (Davidson et al., 2016a). To upscale these plot scale fluxes we completed high resolution vegetation maps in each of our tower sites (Davidson et al., 2016b), which are the finest resolution maps currently available from these sites, and also contributed to larger scale mapping effort (Walker et al., 2016). The soil microbial analysis from soil cores collected across our sites showed an association between overall microbial diversity and latitude, with a higher diversity found in the northerly site and lower diversity in the southerly site, contrary to current knowledge (Wagner et al., accepted). We also measured CH4 and CO2 concentrations in the soil, which showed to be orders of magnitude higher than in the atmosphere (Arndt et al., 2016). Our results contributed to model development (Xu et al., 2016; Kobayashi et al., 2016; Liljedahl et al., 2016; Luus et al., 2017), and to a wide variety of other projects as shown by the hundreds of download of our data from Ameriflux. Overall, this grant resulted in the publication of 25 peer reviewed journal articles, including in high impact factor journals such as PNAS (Proceedings of the National Academy of Sciences of the United States of America), and Nature Climate Change, in addition to five more in review and in preparation, and supported the research of seven PhD students, two master students, and ten undergraduate students. 

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5. Abiotic manganese oxidation by peroxyl radicals generated from the reaction between hydroxyl radicals and their alcohol scavengers

   Gao, Zhenwei; Jun, Young-Shin (August 2022, The 2022 Fall ACS National Meeting & Exposition)

   Environmentally ubiquitous manganese (Mn) oxides play important roles in geochemical element redox cycling. They can be formed by both biotic and abiotic Mn2+(aq) oxidation processes. We recently observed photochemically-assisted abiotic oxidation of Mn2+(aq) to δ-MnO2 nanosheets during nitrate photolysis. Mn2+ was mainly oxidized by superoxide radicals, while hydroxyl radicals (•OH) contributed little to Mn oxidation. However, unexpected abiotic Mn2+ oxidation was observed in the presence of tert-butyl alcohol (TBA) that was added to scavenge •OH. TBA, one of the most common •OH scavengers, has been thought to be able to completely scavenge •OH, leaving less reactive products that do not participate in further redox reactions in the system. However, we discovered that TBA was not an inert agent in scavenging •OH. Secondary peroxyl radicals (ROO•) were produced from the chain reactions between TBA and •OH, facilitating the oxidation of Mn2+ to MnO2(s). These findings can also be applied to other alcohol scavengers, such as methanol, ethanol, and propanol. In addition, ROO• can be produced by the reaction between •OH and unsaturated organic matter in natural environments. This study helps understand the occurrences of Mn oxides in the environment, and it provides new insights into the oxidation pathways of other heavy metals ions (Fe2+, As3+, and Cr3+) by ROO•. 

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