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1. Comparison of Low‐Density Lipoprotein Oxidation by Hydrophilic O( ³ P)‐Precursors and Lipid‐O( ³ P)‐Precursor Conjugates

   https://doi.org/10.1111/php.13803  

   Maness, Peter F.; Cone, Grant W.; Ford, David A.; McCulla, Ryan D. (March 2023, Photochemistry and Photobiology)

   Abstract Lipid oxidation by reactive oxygen species (ROS) provide several different oxidation products that have been implicated in inflammatory responses. Ground state atomic oxygen [O(³P)] is produced by the photodeoxygenation of certain heterocyclic oxides and has a reactivity that is unique from other ROS. Due to the reactive nature of O(³P), the site of O(³P)‐generation is expected to influence the products in heterogenous solutions or environments. In this work, the oxidation of low‐density lipoprotein (LDL) by lipids with covalently bound O(³P)‐photoprecursors was compared to more hydrophilic O(³P)‐photoprecursors. Lipid oxidation products were quantified after Bligh‐Dyer extraction and pentafluorobenzyl bromide (PFB) derivatization by GC–MS. Unlike the more hydrophilic O(³P)‐photoprecursors, the oxidation of LDL during the irradiation of lipid‐(O³P)‐photoprecursor conjugates showed little quenching by the addition of the O(³P)‐scavenging sodium allyl sulfonate. This indicated that lipophilic O(³P)‐photoprecursors are expected to generate lipid oxidation products where other more hydrophilic O(³P)‐photoprecursors could be quenched by other reactive groups present in solution or the environment. 

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2. Long‐term nitrogen deposition inhibits soil priming effects by enhancing phosphorus limitation in a subtropical forest

   https://doi.org/10.1111/gcb.16718  

   Wang, Xiaohong; Li, Shiyining; Zhu, Biao; Homyak, Peter M.; Chen, Guangshui; Yao, Xiaodong; Wu, Dongmei; Yang, Zhijie; Lyu, Maokui; Yang, Yusheng (April 2023, Global Change Biology)

   Abstract It is widely accepted that phosphorus (P) limits microbial metabolic processes and thus soil organic carbon (SOC) decomposition in tropical forests. Global change factors like elevated atmospheric nitrogen (N) deposition can enhance P limitation, raising concerns about the fate of SOC. However, how elevated N deposition affects the soil priming effect (PE) (i.e., fresh C inputs induced changes in SOC decomposition) in tropical forests remains unclear. We incubated soils exposed to 9 years of experimental N deposition in a subtropical evergreen broadleaved forest with two types of¹³C‐labeled substrates of contrasting bioavailability (glucose and cellulose) with and without P amendments. We found that N deposition decreased soil total P and microbial biomass P, suggesting enhanced P limitation. In P unamended soils, N deposition significantly inhibited the PE. In contrast, adding P significantly increased the PE under N deposition and by a larger extent for the PE of cellulose (PE_cellu) than the PE of glucose (PE_glu). Relative to adding glucose or cellulose solely, adding P with glucose alleviated the suppression of soil microbial biomass and C‐acquiring enzymes induced by N deposition, whereas adding P with cellulose attenuated the stimulation of acid phosphatase (AP) induced by N deposition. Across treatments, the PE_gluincreased as C‐acquiring enzyme activity increased, whereas the PE_celluincreased as AP activity decreased. This suggests that P limitation, enhanced by N deposition, inhibits the soil PE through varying mechanisms depending on substrate bioavailability; that is, P limitation regulates the PE_gluby affecting soil microbial growth and investment in C acquisition, whereas regulates the PE_celluby affecting microbial investment in P acquisition. These findings provide new insights for tropical forests impacted by N loading, suggesting that expected changes in C quality and P limitation can affect the long‐term regulation of the soil PE. 

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3. A rational map with infinitely many points of distinct arithmetic degrees

   https://doi.org/10.1017/etds.2019.30  

   LESIEUTRE, JOHN; SATRIANO, MATTHEW (January 2019, Ergodic Theory and Dynamical Systems)

   Let be a dominant rational self-map of a smooth projective variety defined over $$\overline{\mathbb{Q}}$$ . For each point $$P\in X(\overline{\mathbb{Q}})$$ whose forward $$f$$ -orbit is well defined, Silverman introduced the arithmetic degree $$\unicode[STIX]{x1D6FC}_{f}(P)$$ , which measures the growth rate of the heights of the points $$f^{n}(P)$$ . Kawaguchi and Silverman conjectured that $$\unicode[STIX]{x1D6FC}_{f}(P)$$ is well defined and that, as $$P$$ varies, the set of values obtained by $$\unicode[STIX]{x1D6FC}_{f}(P)$$ is finite. Based on constructions by Bedford and Kim and by McMullen, we give a counterexample to this conjecture when $$X=\mathbb{P}^{4}$$ . 

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4. IDTReeS 2020 Competition Data

   https://doi.org/10.5281/zenodo.3700196  

   Graves, Sarah; Marconi, Sergio (January 2020, Zenodo)

   {"Abstract":["Data provided by the Integrating Data science with Trees and Remote Sensing (IDTReeS) research group for use in the IDTReeS Competition.<\/p>\n\nGeospatial and tabular data to be used in two data science tasks focused on using remote sensing data to quantify the locations, sizes and species identities of millions of trees and on determining how these methods generalize to other forests.<\/p>\n\nVector data are the geographic extents of Individual Tree Crown boundaries that have been identified by researchers in the IDTReeS group. The data were generated primarily by Sarah Graves, Sergio Marconi, and Benjamin Weinstein, with support from Stephanie Bohlman, Ethan White, and members of the IDTReeS group.<\/p>\n\nRemote Sensing and Field data were generated by the National Ecological Observatory Network (NEON, Copyright © 2017 Battelle). Data were selected, downloaded, and packaged by Sergio Marconi. The most recent available data of the following products are provided:<\/p>\n\nNational Ecological Observatory Network. 2020. Data Product DP1.30010.001, High-resolution orthorectified camera imagery. Provisional data downloaded from http://data.neonscience.org on March 4, 2020. Battelle, Boulder, CO, USA NEON. 2020.<\/p>\n\nNational Ecological Observatory Network. 2020. Data Product DP1.30003.001, Discrete return LiDAR point cloud. Provisional data downloaded from http://data.neonscience.org on March 4, 2020. Battelle, Boulder, CO, USA NEON. 2020.<\/p>\n\nNational Ecological Observatory Network. 2020. Data Product DP1.10098.001, Woody plant vegetation structure. Provisional data downloaded from http://data.neonscience.org on March 4, 2020. Battelle, Boulder, CO, USA NEON. 2020.<\/p>\n\nNational Ecological Observatory Network. 2020. Data Product DP3.30015.001, Ecosystem structure. Provisional data downloaded from http://data.neonscience.org on March 4, 2020. Battelle, Boulder, CO, USA NEON. 2020.<\/p>\n\nNEON has the following data policy:<\/p>\n\n\u2018The National Ecological Observatory Network is a program sponsored by the National Science Foundation and operated under cooperative agreement by Battelle Memorial Institute. This material is based in part upon work supported by the National Science Foundation through the NEON Program.\u2019<\/p>\n\nTHE NEON DATA PRODUCTS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE NEON DATA PRODUCTS BE LIABLE FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE NEON DATA PRODUCTS.<\/p>"],"Other":["This data is supported by the National Science Foundation through grant 1926542 and by the Gordon and Betty Moore Foundation's Data-Driven Discovery Initiative through grant GBMF4563 to E.P. White, and the NSF Dimension of Biodiversity program grant (DEB-1442280) and USDA/NIFA McIntire-Stennis program (FLA-FOR-005470)."]} 

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5. Synthesis and characterization of modular polyphosphonate homopolymers and copolymers

   https://doi.org/10.1002/pol.20200066  

   Totsch, Timothy R.; Stanford, Victoria L.; Klep, Oleksander; Burdette, Mary K.; Grant, Benjamin; Foulger, Stephen H.; Gray, Gary M. (June 2020, Journal of Polymer Science)

   Abstract Linear polyphosphonates with the generic formula –[P(Ph)(X)OR′O]_n– (X = S or Se) have been synthesized by polycondensations of P(Ph)(NEt₂)₂and a diol (HOR′OH = 1,4‐cyclohexanedimethanol, 1,4‐benzenedimethanol, tetraethylene glycol, or 1,12‐dodecanediol) followed by reaction with a chalcogen. Random copolymers have been synthesized by polycondensations of P(Ph)(NEt₂)₂and mixture of two of the diols in a 2:1:1 mol ratio followed by reaction with a chalcogen. Block copolymers with the generic formula –[P(Ph)(X)OR′O]_(x + 2)–[P(Ph)(X)OR′O]_(x + 3)– (X = S or Se) have been synthesized by the polycondensations of Et₂N[P(Ph)(X)OR′O]_(x + 2)P(Ph)NEt₂oligomers with HOR′O[P(Ph)(X)OR′O]_(x + 3)H oligomers followed by reaction with a chalcogen. The Et₂N[P(Ph)(X)OR′O]_(x + 2)P(Ph)NEt₂oligomers are prepared by the reaction of an excess of P(Ph)(NEt₂)₂with a diol while the HOR′O[P(Ph)(X)OR′O]_(x + 3)H oligomers are prepared by the reaction of P(Ph)(NEt₂)₂with an excess of the diol. In each case the excess, x is the same and determines the average block sizes. All of the polymers were characterized using¹H,¹³C{¹H}, and³¹P{¹H} NMR spectroscopy, TGA, DSC, and SEC.³¹P{¹H} NMR spectroscopy demonstrates that the random and block copolymers have the expected arrangements of monomers and, in the case of block copolymers, verifies the block sizes. All polymers are thermally stable up to ~300°C, and the arrangements of monomers in the copolymers (block vs. random) affect their degradation temperatures andT_gprofiles. The polymers have weight average MWs of up to 3.8 × 10⁴ Da. 

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