Scutoids are a geometrical solution to three-dimensional packing of epithelia

As animals develop, tissue bending contributes to shape the organs into complex three-dimensional structures. However, the architecture and packing of curved epithelia remains largely unknown. Here we show by means of mathematical modelling that cells in bent epithelia can undergo intercalations along the apico-basal axis. This phenomenon forces cells to have different neighbours in their basal and apical surfaces. As a consequence, epithelial cells adopt a novel shape that we term “scutoid”. The detailed analysis of diverse tissues confirms that generation of apico-basal intercalations between cells is a common feature during morphogenesis. Using biophysical arguments, we propose that scutoids make possible the minimization of the tissue energy and stabilize three-dimensional packing. Hence, we conclude that scutoids are one of nature's solutions to achieve epithelial bending. Our findings pave the way to understand the three-dimensional organization of epithelial organs

Structural Characterization of Two New Quaternary Chalcogenides: CuCo2InTe4 and CuNi2InTe4

The crystal structure of the chalcogenide compounds CuCo2InTe4 and CuNi2InTe4, two new members of the I-II2-III-VI4 family, were characterized by Rietveld refinement using X-ray powder diffraction data. Both materials crystallize in the tetragonal space group I4 2m (No. 121), Z = 2, with a stannite-type structure, with the binaries CoTe and NiTe as secondary phases

Author Correction: Scutoids are a geometrical solution to three-dimensional packing of epithelia.

The original version of this Article contained an error in ref. 39, which incorrectly cited 'Fristrom, D. & Fristrom, J. W. in The Development of Drosophila melanogaster (eds. Bate, M. & Martinez-Arias, A.) II, (Cold spring harbor laboratory press, 1993)'. The correct reference is 'Condic, M.L, Fristrom, D. & Fristrom, J.W. Apical cell shape changes during Drosophila imaginal leg disc elongation: a novel morphogenetic mechanism. Development 111: 23-33 (1991)'. Furthermore, the last sentence of the fourth paragraph of the introduction incorrectly omitted citation of work by Rupprecht et al. The correct citation is given below. These errors have now been corrected in both the PDF and HTML versions of the Article. Rupprecht, J.F., Ong, K.H., Yin, J., Huang, A., Dinh, H.H., Singh, A.P., Zhang, S., Yu, W. & Saunders, T.E. Geometric constraints alter cell arrangements within curved epithelial tissues. Mol. Biol. Cell 28, 3582-3594 (2017)

Measurement and analysis of nonhydrostatic lattice strain component in niobium to 145 GPa under various fluid pressure-transmitting media

The d spacings in niobium have been measured to 145 GPa with a diamond anvil cell using a fluid13; pressure-transmitting medium methanolx2013;ethanolx2013;water MEW mixture, or helium. The13; conventional geometry, wherein the primary x-ray beam passes parallel to the load axis with image13; plate, has been used to record the diffraction patterns. The analysis of the d spacings using the lattice13; strain equations indicates the presence of nonhydrostatic stress component with both MEW and He13; pressure-transmitting media in the pressure ranges that are well below the freezing pressure of the13; pressure-transmitting medium. A method to correct the measured d spacings for the nonhydrostatic13; pressure effect is suggested. This study clearly emphasizes the need to carefully analyze the data for13; the nonhydrostatic compression effects even if the experiments are performed with fluid13; pressure-transmitting medium

Structure Refinement of the Semiconducting Compound Cu3TaS4Cu_3TaS_4 from X-Ray Powder Diffraction Data

The ternary compound $Cu_{3}TaS_{4}$ has been investigated by means of X-ray powder diffraction and its structure has been refined by the Rietveld method. This compound is isostructural with the sulvanite mineral $Cu_{3}VS_{4}$, and crystallizes in the cubic $P \bar{4} 3m$ space group (No. 215), Z = 1, with unit cell parameters a = 5.5145(1) Å and V = 167.70(1) $Å^{3}$. The refinement of 14 instrumental and structural parameters converged to $R_{p}$ = 4.4%, $R_{wp}$ = 6.8%, $R_{exp}$ = 5.5% and S = 1.2 for 4501 step intensities and 33 independent reflections

Preparation, thermal analysis, and crystal structure refinement of the quaternary alloy (CuIn)2NbTe5

The quaternary alloy (CuIn)2NbTe5 was synthesized by solid-state reaction using the melt and annealing technique. The thermal analysis shows that this compound melts at 1026 K. The present alloy is isotypic with Cu2FeIn2Se5 and crystallizes in the space group P¹42c (N°112),with unit cell parameters a = 6:1964(2) ° A, c = 12:4761(4) ° A, c=a = 2:01, V = 479:02(3) °A3. (CuIn)2NbTe5, belonging to the system(CuInSe2)1-x(FeSe)x with x = 1/3, is a new adamantane compound with a P¡chalcopyrite structure. This structure is characterized by adouble alternation of anions-cations layers according to the Te-Te: Nb-In-Nb-In: Cu-In-Cu-In: Te-Te sequence, along the 010 directio

Uniaxial Stress Component in WC Toroidal Anvils under High Pressure and Temperature

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Crystal structure and powder X-ray diffraction data of the super-paramagnetic compound CuFeInTe3

The crystal structure of the new CuFeInTe3quaternary compound was studied by the Rietveld method from powder X-ray diffraction data. The CuFeInTe3compound crystallize in the tetragonal CuFeInTe3-type structure with space group P¹4 2c (N±112), and unit cell parameters a = 6.1842(1) ° A, c = 12.4163(2) ° A, V = 474.85(1) °A3. The density of CuFeInTe3is ½x = 5:753 g cm¡3. The reliability factors of the Rietveld refinement results are Rp= 5:5%, Rwp= 6:1%, Rexp= 4:7%, and S = 1:3. The powder XRD data of CuFeInTe3are presented and the figures of merit of indexation are M20= 79:4 and F30= 43:3 (0.0045, 154)

Preparation and characterization of (CuInSe2)1-x(CoSe)x alloys in the composition range 0 x 2/3.

Polycrystalline samples of (CuInSe2)1-x(CoSe)x alloys were prepared by the normal melt and anneal technique in the composition range 0 < x 2/3. The obtained ingots were characterized by scanning electron microscopy, X-ray diffraction and differential thermal analysis techniques. A sample with x = 2/3 (prepared a posteriori) was also studied by the Raman shift technique. The results showed a complex behavior of the phase diagram. The phase () with chalcopyrite structure exists in a narrow interval 0 < x < 0.1 in the composition range; then, for 0.1 < x < 0.25, the ordered phase gradually transforms into a disordered () phase where the cation sites are multi-occupied (Cu, Co and In) at random. For 0.25 < x < 0.35, two phases were observed, the phase and another, not identified () phase. Finally, for 0.35 < x < 2/3, another chalcopyrite-like phase () was observed together with traces of the phase. The sequence of phase transformations in the studied composition range seems to be alpha alpha' alpha'+Y alpha''+Y