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1. Growth and morphogenesis of the gastropod shell

   https://doi.org/10.1073/pnas.1816089116  

   Johnson, Adam B. ; Fogel, Nina S. ; Lambert, J. David ( March 2019 , Proceedings of the National Academy of Sciences)

   Gastropod shell morphologies are famously diverse but generally share a common geometry, the logarithmic coil. Variations on this morphology have been modeled mathematically and computationally but the developmental biology of shell morphogenesis remains poorly understood. Here we characterize the organization and growth patterns of the shell-secreting epithelium of the larval shell of the basket whelkTritia(also known asIlyanassa). Despite the larval shell’s relative simplicity, we find a surprisingly complex organization of the shell margin in terms of rows and zones of cells. We examined cell division patterns with EdU incorporation assays and found two growth zones within the shell margin. In the more anterior aperture growth zone, we find that inferred division angles are biased to lie parallel to the shell edge, and these divisions occur more on the margin’s left side. In the more posterior mantle epithelium growth zone, inferred divisions are significantly biased to the right, relative to the anterior–posterior axis. These growth zones, and the left–right asymmetries in cleavage patterns they display, can explain the major modes of shell morphogenesis at the level of cellular behavior. In a gastropod with a different coiling geometry,Planorbellasp., we find similar shell margin organization and growth zones asTritia, but different left–right asymmetries than we observed in the helically coiled shell ofTritia. These results indicate that differential growth patterns in the mantle edge epithelium contribute to shell shape in gastropod shells and identify cellular mechanisms that may vary to generate shell diversity in evolution.

    

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2. Shell model results for nuclear β−-decay properties of sd-shell nuclei

   https://doi.org/10.1093/ptep/ptaa012  

   Kumar, Anil ; Srivastava, Praveen C ; Suzuki, Toshio ( March 2020 , Progress of Theoretical and Experimental Physics)

   Abstract We evaluate the allowed $\beta^-$-decay properties of nuclei with $Z = 8$–$15$ systematically under the framework of the nuclear shell model using the valence space Hamiltonians derived from modern ab initio methods, such as in-medium similarity renormalization group and coupled-cluster theory. For comparison we also show results obtained with fitted interaction derived from chiral effective field theory and phenomenological universal $sd$-shell Hamiltonian version B interaction. We have performed calculations for O $\rightarrow$ F, F $\rightarrow$ Ne, Ne $\rightarrow$ Na, Na $\rightarrow$ Mg, Mg $\rightarrow$ Al, Al $\rightarrow$ Si, Si $\rightarrow$ P, and P $\rightarrow$ S transitions. Theoretical results for $B(GT)$, $\log ft$ values, and half-lives are discussed and compared with the available experimental data. 

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3. Static and dynamic properties of shell-shaped condensates

   https://doi.org/10.1103/PhysRevA.98.013609  

   Sun, Kuei ; Padavić, Karmela ; Yang, Frances ; Vishveshwara, Smitha ; Lannert, Courtney ( July 2018 , Physical Review A)
4. Stability Landscape of Shell Buckling

   https://doi.org/10.1103/PhysRevLett.119.224101  

   Virot, Emmanuel ; Kreilos, Tobias ; Schneider, Tobias M. ; Rubinstein, Shmuel M. ( November 2017 , Physical Review Letters)
5. Methane Hydration‐Shell Structure and Fragility

   https://doi.org/10.1002/anie.201809372  

   Wu, Xiangen ; Lu, Wanjun ; Streacker, Louis M. ; Ashbaugh, Henry S. ; Ben‐Amotz, Dor ( October 2018 , Angewandte Chemie International Edition)

   The influence of oily molecules on the structure of liquid water is a question of importance to biology and geology and many other fields. Previous experimental, theoretical, and simulation studies of methane in liquid water have reached widely conflicting conclusions regarding the structure of hydrophobic hydration‐shells. Herein we address this question by performing Raman hydration‐shell vibrational spectroscopic measurements of methane in liquid water from −10 °C to 300 °C (at 30 MPa, along a path that parallels the liquid‐vapor coexistence curve). We show that, near ambient temperatures, methane's hydration‐shell is slightly more tetrahedral than pure water. Moreover, the hydration‐shell undergoes a crossover to a more disordered structure above ca. 85 °C. Comparisons with the crossover temperature of aqueous methanol (and other alcohols) reveal the stabilizing influence of an alcohol OH head‐group on hydrophobic hydration‐shell fragility.

    

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