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1. Electron-impact excitation of the 5$$\varvec{\,^2\mathbf{S}_{1/2} \rightarrow 5\,^2\mathbf{P}_{1/2}}$$ and 5$$\varvec{\,^2\mathbf{P}_{3/2}}$$ transitions in rubidium by 40 eV electrons: theory and experiment

   https://doi.org/10.1140/epjd/s10053-022-00413-7  

   Hamilton, K. R.; Zatsarinny, O.; Bartschat, K.; Predojević, B.; Šević, D.; Marinković, B. P.; Brunger, M. J. (May 2022, The European Physical Journal D)

   Abstract We report on a series of detailed Breit-Pauli and Dirac B-spline R-matrix (DBSR) differential cross section (DCS) calculations for excitation of the $$5\,^2\mathrm{S}_{1/2} \rightarrow 5\,^2\mathrm{P}_{1/2}$$ 5 2 S 1 / 2 → 5 2 P 1 / 2 and $$5\,^2\mathrm{S}_{1/2}\rightarrow 5\,^2\mathrm{P}_{3/2}$$ 5 2 S 1 / 2 → 5 2 P 3 / 2 states in rubidium by 40 eV incident electrons. The early BP computations shown here were carried out with both 5 states and 12 states, while the DBSR models coupled 150 and 325 states, respectively. We also report corresponding results from a limited set of DCS measurements on the unresolved $$5\,^2\mathrm{P}_{1/2,3/2}$$ 5 2 P 1 / 2 , 3 / 2 states, with the experimental data being restricted to the scattered electron angular range 2– $$10^\circ $$ 10 ∘ . Typically, good agreement is found between our calculated and measured DCS for excitation of the unresolved $$5\,^2\mathrm{P}_{1/2,3/2}$$ 5 2 P 1 / 2 , 3 / 2 states, with best accord being found between the DBSR predictions and the measured data. The present theoretical and experimental results are also compared with predictions from earlier 40 eV calculations using the nonrelativistic Distorted-Wave Born Approximation and a Relativistic Distorted-Wave model. Graphic abstract 

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2. Stable minimal hypersurfaces in $$\mathbf{R}^5$$

   https://doi.org/10.4007/annals.2026.204.1.5  

   Chodosh, Otis; Li, Chao; Minter, Paul; Stryker, Douglas (July 2026, Annals of Mathematics)

   We show that a complete, two-sided stable minimal hypersurface in 𝐑^5 is flat. 

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3. A structural and computational comparison of close contacts and related intermolecular energies of interaction in the structures of 1,3-diiodo-5-nitrobenzene, 1,3-dibromo-5-nitrobenzene, and 1,3-dichloro-5-nitrobenzene

   https://doi.org/10.1107/S2053229622009275  

   Bosch, Eric; Bowling, Nathan P.; Speetzen, Erin D. (October 2022, Acta Crystallographica Section C Structural Chemistry)

   1,3-Diiodo-5-nitrobenzene, C₆H₃I₂NO₂, and 1,3-dibromo-5-nitrobenzene, C₆H₃Br₂NO₂, crystallize in the centrosymmetric space groupP2₁/m, and are isostructural with 1,3-dichloro-5-nitrobenzene, C₆H₃Cl₂NO₂, that has been redetermined at 100 K for consistency. While the three-dimensional packing in all three structures is similar, the size of the halogen atom affects the nonbonded close contacts observed between molecules. Thus, the structure of 1,3-diiodo-5-nitrobenzene features a close Type 1 I...I contact, the structure of 1,3-dibromo-5-nitrobenzene features a self-complementary nitro-O...Br close contact, while the structure of 1,3-dichloro-5-nitrobenzene also has a self-complementary nitro-O...Cl interaction, as well as a bifurcated C—H...O(nitro) close contact. Notably, the major energetically attractive intermolecular interaction between adjacent molecules in each of the three structures corresponds to a π-stacked interaction. The self-complementary halogen...O(nitro) and C—H...O(nitro) interactions correspond to significant cohesive attraction between molecules in each structure, while the Type 1 halogen–halogen contact is weakly cohesive. 

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4. Conserved 5-methyluridine tRNA modification modulates ribosome translocation

   https://doi.org/10.1073/pnas.2401743121  

   Jones, Joshua D; Franco, Monika K; Giles, Rachel N; Eyler, Daniel E; Tardu, Mehmet; Smith, Tyler J; Snyder, Laura R; Polikanov, Yury S; Kennedy, Robert T; Niederer, Rachel O; et al (August 2024, Proceedings of the National Academy of Sciences)

   While the centrality of posttranscriptional modifications to RNA biology has long been acknowledged, the function of the vast majority of modified sites remains to be discovered. Illustrative of this, there is not yet a discrete biological role assigned for one of the most highly conserved modifications, 5-methyluridine at position 54 in tRNAs (m⁵U54). Here, we uncover contributions of m⁵U54 to both tRNA maturation and protein synthesis. Our mass spectrometry analyses demonstrate that cells lacking the enzyme that installs m⁵U in the T-loop (TrmA inEscherichia coli, Trm2 inSaccharomyces cerevisiae) exhibit altered tRNA modification patterns. Furthermore, m⁵U54-deficient tRNAs are desensitized to small molecules that prevent translocation in vitro. This finding is consistent with our observations that relative to wild-type cells,trm2Δcell growth and transcriptome-wide gene expression are less perturbed by translocation inhibitors. Together our data suggest a model in which m⁵U54 acts as an important modulator of tRNA maturation and translocation of the ribosome during protein synthesis. 

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5. Ten Compatible Poisson Brackets on $$\mathbb P^5$$

   https://doi.org/10.3842/SIGMA.2023.059  

   Nordstrom, Ville; Polishchuk, Alexander (August 2023, Symmetry, Integrability and Geometry: Methods and Applications)

   We give explicit formulas for ten compatible Poisson brackets on $$\mathbb P^5$$ found in arXiv:2007.12351. 

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