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1. Modulation of sensory perception by hydrogen peroxide enables Caenorhabditis elegans to find a niche that provides both food and protection from hydrogen peroxide

   https://doi.org/10.1371/journal.ppat.1010112  

   Schiffer, Jodie A.; Stumbur, Stephanie V.; Seyedolmohadesin, Maedeh; Xu, Yuyan; Serkin, William T.; McGowan, Natalie G.; Banjo, Oluwatosin; Torkashvand, Mahdi; Lin, Albert; Hosea, Ciara N.; et al (December 2021, PLOS Pathogens)

   Weaver, Benjamin (Ed.)

   Hydrogen peroxide (H 2 O 2 ) is the most common chemical threat that organisms face. Here, we show that H 2 O 2 alters the bacterial food preference of Caenorhabditis elegans , enabling the nematodes to find a safe environment with food. H 2 O 2 induces the nematodes to leave food patches of laboratory and microbiome bacteria when those bacterial communities have insufficient H 2 O 2 -degrading capacity. The nematode’s behavior is directed by H 2 O 2 -sensing neurons that promote escape from H 2 O 2 and by bacteria-sensing neurons that promote attraction to bacteria. However, the input for H 2 O 2 -sensing neurons is removed by bacterial H 2 O 2 -degrading enzymes and the bacteria-sensing neurons’ perception of bacteria is prevented by H 2 O 2 . The resulting cross-attenuation provides a general mechanism that ensures the nematode’s behavior is faithful to the lethal threat of hydrogen peroxide, increasing the nematode’s chances of finding a niche that provides both food and protection from hydrogen peroxide. 

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2. California dominates U.S. emissions of the pesticide and potent greenhouse gas sulfuryl fluoride

   https://doi.org/10.1038/s43247-024-01294-x  

   Gaeta, Dylan C.; Mühle, Jens; Vimont, Isaac J.; Crotwell, Molly; Hu, Lei; Miller, John B.; McKain, Kathryn; Baier, Bianca C.; Zhang, Mingyang; Bao, Jianing; et al (April 2024, Communications Earth & Environment)

   Abstract Sulfuryl fluoride (SO₂F₂) is a synthetic pesticide and a potent greenhouse gas that is accumulating in the global atmosphere. Rising emissions are a concern since SO₂F₂has a relatively long atmospheric lifetime and a high global warming potential. The U.S. is thought to contribute substantially to global SO₂F₂emissions, but there is a paucity of information on how emissions of SO₂F₂are distributed across the U.S., and there is currently no inventory of SO₂F₂emissions for the U.S. or individual states. Here we provide an atmospheric measurement-based estimate of U.S. SO₂F₂emissions using high-precision SO₂F₂measurements from the NOAA Global Greenhouse Gas Reference Network (GGGRN) and a geostatistical inverse model. We find that California has the largest SO₂F₂emissions among all U.S. states, with the highest emissions from southern coastal California (Los Angeles, Orange, and San Diego counties). Outside of California, only very small and infrequent SO₂F₂emissions are detected by our analysis of GGGRN data. We find that California emits 60-85% of U.S. SO₂F₂emissions, at a rate of 0.26 ( ± 0.10) Gg yr⁻¹. We estimate that emissions of SO₂F₂from California are equal to 5.5–12% of global SO₂F₂emissions. 

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3. Stability of adsorption of Mg and Na on sulfur-functionalized MXenes

   https://doi.org/10.1039/d1cp03433b  

   Chaney, G.; Çakır, D.; Peeters, F. M.; Ataca, C. (November 2021, Physical Chemistry Chemical Physics)

   Two-dimensional materials composed of transition metal carbides and nitrides (MXenes) are poised to revolutionize energy conversion and storage. In this work, we used density functional theory (DFT) to investigate the adsorption of Mg and Na adatoms on five M 2 CS 2 monolayers (where M = Mo, Nb, Ti, V, and Zr) for battery applications. We assessed the stability of the adatom ( i.e. Na and Mg)-monolayer systems by calculating adsorption and formation energies, as well as voltages as a function of surface coverage. For instance, we found that Mo 2 CS 2 cannot support a full layer of Na nor even a single Mg atom. Na and Mg exhibit the strongest binding on Zr 2 CS 2 , followed by Ti 2 CS 2 , Nb 2 CS 2 and V 2 CS 2 . Using the nudged elastic band method (NEB), we computed promising diffusion barriers for both dilute and nearly full ion surface coverage cases. In the dilute ion adsorption case, a single Mg and Na atom on Ti 2 CS 2 experience ∼0.47 eV and ∼0.10 eV diffusion barriers between the lowest energy sites, respectively. For a nearly full surface coverage, a Na ion moving on Ti 2 CS 2 experiences a ∼0.33 eV energy barrier, implying a concentration-dependent diffusion barrier. Our molecular dynamics results indicate that the three (one) layers (layer) of the Mg (Na) ion on both surfaces of Ti 2 CS 2 remain stable at T = 300 K. While, according to voltage calculations, Zr 2 CS 2 can store Na up to three atomic layers, our MD simulations predict that the outermost layers detach from the Zr 2 CS 2 monolayer due to the weak interaction between Na ions and the monolayer. This suggests that MD simulations are essential to confirm the stability of an ion-electrode system – an insight that is mostly absent in previous studies. 

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4. The smallest 4f-metalla-aromatic molecule of cyclo-PrB ₂ ⁻ with Pr–B multiple bonds

   https://doi.org/10.1039/D2SC02852B  

   Wang, Zhen-Ling; Chen, Teng-Teng; Chen, Wei-Jia; Li, Wan-Lu; Zhao, Jing; Jiang, Xue-Lian; Li, Jun; Wang, Lai-Sheng; Hu, Han-Shi (August 2022, Chemical Science)

   The concept of metalla-aromaticity proposed by Thorn–Hoffmann ( Nouv. J. Chim . 1979, 3, 39) has been expanded to organometallic molecules of transition metals that have more than one independent electron-delocalized system. Lanthanides, with highly contracted 4f atomic orbitals, are rarely found in multiply aromatic systems. Here we report the discovery of a doubly aromatic triatomic lanthanide-boron molecule PrB 2 − based on a joint photoelectron spectroscopy and quantum chemical investigation. Global minimum structural searches reveal that PrB 2 − has a C 2v triangular structure with a paramagnetic triplet 3 B 2 electronic ground state, which can be viewed as featuring a trivalent Pr(III,f 2 ) and B 2 4− . Chemical bonding analyses show that this cyclo-PrB 2 − species is the smallest 4f-metalla-aromatic system exhibiting σ and π double aromaticity and multiple Pr–B bonding characters. It also sheds light on the formation of the rare B 2 4− tetraanion by the high-lying 5d orbitals of the 4f-elements, completing the isoelectronic B 2 4− , C 2 2− , N 2 , and O 2 2+ series. 

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5. Conformational control through co-operative nonconventional C—H...N hydrogen bonds

   https://doi.org/10.1107/S2053229621007427  

   Bosch, Eric; Bowling, Nathan P.; Oburn, Shalisa M. (August 2021, Acta Crystallographica Section C Structural Chemistry)

   null (Ed.)

   We report the design, synthesis, and crystal structure of a conjugated aryleneethynyl molecule, 2-(2-{4,5-dimethoxy-2-[2-(2,3,4-trifluorophenyl)ethynyl]phenyl}ethynyl)-6-[2-(pyridin-2-yl)ethynyl]pyridine, C 30 H 17 F 3 N 2 O 2 , that adopts a planar rhombus conformation in the solid state. The molecule crystallizes in the space group P -1, with Z = 2, and features two intramolecular sp 2 -C—H...N hydrogen bonds that co-operatively hold the arylethynyl molecule in a rhombus conformation. The H atoms are activated towards hydrogen bonding since they are situated on a trifluorophenyl ring and the H...N distances are 2.470 (16) and 2.646 (16) Å, with C—H...N angles of 161.7 (2) and 164.7 (2)°, respectively. Molecular electrostatic potential calculations support the formation of C—H...N hydrogen bonds to the trifluorophenyl moiety. Hirshfeld surface analysis identifies a self-complementary C—H...O dimeric interaction between adjacent 1,2-dimethoxybenzene segments that is shown to be common in structures containing that moiety. 

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