863 research outputs found
Surface structure of Pd(111) with less than half a monolayer of Zn
No full textWe have characterized the structural properties of submonolayer amounts of Zn on Pd(111) using
scanning tunneling microscopy (STM) and spot-profile analysis low energy electron diffraction (SPA-LEED).
Following room temperature deposition of E0.06 monolayers (ML) Zn onto Pd(111), we observe the
substitution of Zn for Pd in the surface layer. At E0.20 ML of deposited Zn, STM reveals a locally ordered
phase with a 2/sqrt3x2/sqrt3R30deg unit cell located near Zn substitutions; SPA-LEED patterns reveal the
same periodicity. We attribute this phase to the metastable bonding of atoms or clusters predominantly
in hollow sites surrounding Zn substitutions in the surface layer. At Therta=0.4 ML, STM images reveal local 2/sqrt3x2/sqrt3R30deg and (2x1) ordering on surfaces annealed to 350 K. At coverages near 0.5 ML, both STM and SPA-LEED show the onset of the formation of the (2x1) ordering associated with the Zn: Pd 1 : 1
alloy phase. At all coverages, the surface is dominated by island growth; the islands’ size and density is
shown to depend critically on annealing at temperatures as low as 350 K. These results provide insight
into the structural features of a Zn/Pd(111) coverage regime that has been much debated in recent years
A low-loss origami plasmonic waveguide
No full textDNA assembles silver and gold nanoparticles for fast and efficient energy transfer</jats:p
Taxonomy and nomenclature of the southern Malagasy Kalanchoe peltigera, with reference to K. rosei var. seyrigii (Crassulaceae subfam. Kalanchooideae)
No full textShtein, Ronen, Smith, Gideon F. (2021): Taxonomy and nomenclature of the southern Malagasy Kalanchoe peltigera, with reference to K. rosei var. seyrigii (Crassulaceae subfam. Kalanchooideae). Phytotaxa 490 (1): 47-59, DOI: 10.11646/phytotaxa.490.1.4, URL: http://dx.doi.org/10.11646/phytotaxa.490.1.
Photonic crystals: Sustainable sensors from silk
No full textSunghwan Kim and co-workers demonstrated the controlled fabrication of a silk inverse opal (SIO), a type of photonic crystal, from fibroin, a silk-derived protein that meets all the criteria for sustainability. The extracted fibroin solution is poured over a self-assembled colloidal crystal of close-packed poly(methyl methacrylate) (PMMA) spheres and left to dry. The PMMA is then dissolved, leaving an inverse lattice of fibroin. The periodic variation of the refractive index between the lattice and the voids imparts structural color to the crystal. Kim and co-researchers control the color of the SIOs, both by varying the size of the PMMA spheres and by filling the voids with acetone. They then irradiate their samples with white light, and observe that the color of their crystals changes according to the specified optogeometric parameters
FIGURE 2. A in Taxonomy and nomenclature of the southern Malagasy Kalanchoe peltigera, with reference to K. rosei var. seyrigii (Crassulaceae subfam. Kalanchooideae)
No full textFIGURE 2. A. Flower (insert) and leaves and habit of horticultural material of Kalanchoe daigremontiana; cultivated in South Africa (insert) and in Israel. B. A "shield"-like leaf of K. peltigera bearing bulbils; a clone of the material deposited as the holotype, in cultivation in Japan, and a flower (insert), from the same clone, cultivated in Israel. C. General morphology of K. rosei var. rosei with trilobate leaves; cultivated in South Africa. D. Flowers and leaves of simple-, non-peltate-leafed Kalanchoe material such as this is often attributed to K. rosei var. rosei; cultivated in Israel. Photograph credits: A (insert). Gideon F. Smith; B. Jun Ikeda; C. Maddy Ogden; A, B (insert), D. Ronen Shtein. Elements are not to scale.Published as part of Shtein, Ronen & Smith, Gideon F., 2021, Taxonomy and nomenclature of the southern Malagasy Kalanchoe peltigera, with reference to K. rosei var. seyrigii (Crassulaceae subfam. Kalanchooideae), pp. 47-59 in Phytotaxa 490 (1) on page 49, DOI: 10.11646/phytotaxa.490.1.4, http://zenodo.org/record/575575
FIGURE 8 in A new status for two varieties previously included in the southern Malagasy Kalanchoe rosei, now included in K. variifolia (Crassulaceae subfam. Kalanchooideae)
No full textFIGURE 8. Comparison of corollae of selected taxa of Kalanchoe subg. Bryophyllum, especially showing the corolla stipe. A. K. daigremontiana. B. Simple-, non-peltate-leaved Kalanchoe often attributed to K. rosei var. rosei. C. K. peltigera. D. K. variifolia var. seyrigii (R. Shtein 746). E. K. ×richaudii. F. K. marnieriana. G. K. laxiflora. H. K. serrata. I. K. tenuiflora. J. K. ×lokarana. All elements to scale. Corollae bases very shortly stipitate are also shown in a 2× magnification. Photograph credits: Ronen Shtein.Published as part of Shtein, Ronen, Klein, David-Paul & Smith, Gideon F., 2021, A new status for two varieties previously included in the southern Malagasy Kalanchoe rosei, now included in K. variifolia (Crassulaceae subfam. Kalanchooideae), pp. 228-244 in Phytotaxa 496 (3) on page 241, DOI: 10.11646/phytotaxa.496.3.2, http://zenodo.org/record/542370
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