A volume-porous conductive electrode by hexagonal close packing of phenolic resin-based carbon spheres

The eyespot of the marine dinoflagellate Glenodinium foliaceum is a flattened orange structure, more or less trapezoid in shape with an anterior hook-like projection. It is situated on the ventral side of the organism in the vicinity of the flagellar bases at the anterior end of the sulcus. In the electron microscope the eyespot is seen to contain two layers of osmiophilic granules 80-200 nm in diameter which usually show hexagonal close-packing. The eyespot is surrounded by a triple-membraned envelope and is not connected to any other organelle. Adjacent to the eyespot is a distinctive organelle termed the ‘lamellar body’. This consists of a stack of up to 50 flattened vesicles or disks, each 16 nm thick and about 750 nm wide, the whole being orientated in an antero-posterior direction. The lamellae are continuous, at the ends of the stack, with rough endoplasmic reticulum and are joined together by occasional bridges at their edges. The bases of the two flagella lie just ventral to the lamellar body and from them roots arise which pass by the eyespot and join the subthecal microtubular system. The eyespot of Glenodinium is unique both in structure and the presence of the associated lamellar body. It differs from eyespots which have been described from other algal groups and also from the more complex ocellus found in certain dinoflagellates belonging to the order Warnowiaceae. The method by which the eyespot functions is discussed and it is suggested that unidirectional stimuli could be perceived by shading of the lamellar body.

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Topological signatures and stability of hexagonal close packing and Barlow stackings

Soft Matter ◽

10.1039/d1sm00774b ◽

2021 ◽

Author(s):

Georg Osang ◽

Herbert Edelsbrunner ◽

Mohammad Saadatfar

Keyword(s):

Close Packing ◽

Hexagonal Close Packing ◽

X Ray ◽

3D Rendering

3D rendering of the experimental packing obtained via X-ray CT. A cut-out section shows the bulk crystallisation and partially crystallised regions.

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Cubic Close Packing versus Hexagonal Close Packing

Wolfram Demonstrations Project ◽

10.3840/003575 ◽

2008 ◽

Keyword(s):

Close Packing ◽

Hexagonal Close Packing

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Synthese und Struktur von Nb0,89Fe0,93Te2 und Ta0,77Fe0,90Te2 / Synthesis and Structure of Nb0.89Fe0.93Te2 and Ta0.77Fe0.90Te2

Zeitschrift für Naturforschung B ◽

10.1515/znb-1992-0901 ◽

1992 ◽

Vol 47 (9) ◽

pp. 1203-1212 ◽

Cited By ~ 7

Author(s):

Jörg Neuhausen ◽

Karl-Ludwig Stork ◽

Elisabeth Potthoff ◽

Wolfgang Tremel

Keyword(s):

Single Crystal ◽

Crystal Structures ◽

Chemical Transport ◽

Structure Type ◽

Close Packing ◽

Hexagonal Close Packing ◽

X Ray ◽

The Relationship

Nb0.89Fe0.93Te2 and Ta0.77Fe0.90Te2 were prepared by chemical transport reactions. The crystal structures of both compounds were determined using X-ray single crystal methods. The structures of the layer compounds Nb0.89Fe0.93Te2 (Pmna, Z = 2, a = 7.951(1) Å, b = 7.241(1) A, c = 6.233(1) Å) and Ta0.77Fe0.90Te2 (Pmna, Z = 2, a = 7.890(2) Å, b = 7.252(2) Å, c = 6.192(1) Å) are based on a hexagonal close packing of Te atoms. Approximately one-half of the octahedral holes in this packing are occupied by Nb (Ta) atoms, about one-quarter of the tetrahedral holes are occupied by Fe atoms. The relationship to the NiAs structure type is discussed.

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