Pyramid prism

An ideal wave-front sensor (WFS) for an adaptive optics system prioritizes three properties: high sensitivity, wide dynamic range, and a linear relationship between the actual and estimated wave fronts. WFSs currently in operation can claim superiority in only two of these properties. For example, the Shack-Hartmann WFS (SHWFS) has a linear response and remains effective under large aberrations, but its sensitivity to low spatial frequencies is limited [Proc. SPIE5490, 1177 (2004)PSISDG0277-786X10.1117/12.550786]...

Antifreeze proteins (AFPs) can inhibit the freezing of body fluid at subzero temperatures to promote the survival of various organisms living in polar regions. Type III AFPs are categorized into three subgroups, QAE1, QAE2, and SP isoforms, based on differences in their isoelectric points. We determined the thermal hysteresis (TH), ice recrystallization inhibition (IRI), and cryopreservation activity of three isoforms of the notched-fin eelpout AFP and their mutant constructs and characterized their structural and dynamic features using NMR...

Ancient pagodas are usually parts of hot tourist spots in many oriental countries due to their unique historical backgrounds. They are usually polygonal structures comprised by multiple floors, which are separated by eaves. In this paper, we propose a new method to investigate both the rotational and reflectional symmetry of such polygonal pagodas through developing novel geometric models to fit to the 3D point clouds obtained from photogrammetric reconstruction. The geometric model consists of multiple polygonal pyramid/prism models but has a common central axis...

Reverspectives are paintings created by the English artist Patrick Hughes. They are 3D structures, for example, pyramids or prisms, which elicit an illusory depth perception that corresponds to the reverse of the physical depth layout. Rogers and Gyani state that " the perspective information provided by a simple grid of vertical and horizontal lines on a slanting surface can be just as powerful as the information provided by a rich, naturalistic scene ". The present experiment was aimed to further investigate this perspective reversal...

The structural evolution and electronic properties of TaSi n -/0 ( n = 2-15) clusters are explored using anion photoelectron spectroscopy accompanied by quantum chemical calculations. The Ta atom in TaSi n -/0 is inclined to interact with more Si atoms and has high coordination numbers. The theoretical calculations show that TaSi2 -/0 have trianglur structures and TaSi3 -/0 adopt pyramid structures, while the geometries of TaSi n -/0 ( n = 4-7) are all exohedral structures dominated by bipyramid-based configurations with the Ta atom face-capping the Si n motifs...

Our ability to synthesize faceted nanoparticles of tunable shapes and sizes has opened up many intriguing applications of such particles. However, our progress in understanding, modeling, and simulating their collective rheology, phase behavior, and self-assembly has been hindered by the lack of analytical interparticle interaction potentials. Here, we present one of the first analytical models for the van der Waals interaction energy between faceted nanoparticles. The model was derived through various approximations that reduce the usual six-dimensional integral over particle volumes to a series of two-dimensional integrals over particle interaction areas with closed-form solutions...

The reaction of [Ni6 (CO)12 ]2- as a [NBu4 ]+ salt in CH2 Cl2 with 0.8 equiv of PCl3 afforded [Ni14 P2 (CO)22 ]2- . In contrast, the reactions of [Ni6 (CO)12 ]2- as a [NEt4 ]+ salt with 0.4-0.5 equiv of POCl3 afforded [Ni22- x P2 (CO)29- x ]4- ( x = 0.84) or [Ni39 P3 (CO)44 ]6- by using CH3 CN and thf as a solvent, respectively. Moreover, by using 0.7-0.9 mol of POCl3 per mole of [NEt4 ]2 [Ni6 (CO)12 ] both in CH3 CN and thf, [Ni23- x P2 (CO)30- x ]4- ( x = 0.82) was obtained together with [Ni22 P6 (CO)30 ]2- as a side product...

III-nitrides are considered the material of choice for light-emitting diodes (LEDs) and lasers in the visible to ultraviolet spectral range. The development is hampered by lattice and thermal mismatch between the nitride layers and the growth substrate leading to high dislocation densities. In order to overcome the issue, efforts have gone into selected area growth of nanowires (NWs), using their small footprint in the substrate to grow virtually dislocation-free material. Their geometry is defined by six tall side-facets and a pointed tip which limits the design of optoelectronic devices...

A new ternary nonstoichiometric Zr6.5 Pt6 Se19 has been discovered as a part of effort to dope Zr into the layered transitional metal chalcogenide PtSe2 . With a new structure type ( oC 68), it is the first Pt-based ternary chalcogenide with group 4 elements (Ti, Zr, and Hf). The crystal structure adopts the orthorhombic space group Cmmm with lattice parameters of a = 15.637(6) Å, b = 26.541(10) Å, c = 3.6581(12) Å, and V = 1518.2(9) Å3 . This unusual structure consists of several building units: chains of edge-sharing selenium trigonal prisms and octahedra centered by zirconium atoms, chains of corner-shared square pyramid, and square planar centered by Pt atoms...

A new nonanuclear heterometal five-layer sandwich silicotungstate [H2 N(CH3 )2 ]6 H5 NaK{[NaMn8 O6 (OAc)6 ][ A-α- SiW9 O34 ]2 }·34H2 O ( 1 ) has been made under hydrothermal reactions of MnCl2 ·4H2 O, KMnO4 , trivacant [ A -α-SiW9 O34 ]10- {SiW9 } fragment, and [H2 N(CH3 )2 ]·Cl in NaOAc-HOAc buffer (pH = 4.8). The polyoxoanion of 1 is a sandwich architecture, in which the nonanuclear heterometal cluster [NaMn8 O6 (OAc)6 ]7+ made of two triangular pyramid clusters [Mn4 O3 (OAc)3 ]3+ {Mn4 } via a hexacoordinate antitrigonal prism Na+ linkage is encapsulated by two trivacant fragments of {SiW9 }...

Scientists can change programmed DNA strands to adjust edge length and vertex junction to control the 3D structures with precision space signatures. The number of strands plays an important role in sequence design, synthesis and constitutive property. However, the majority of DNA branched polyhedra comprise a number of single strands. Therefore, it is crucial to make the number of strands to be calculated as less as possible. DNA polyhedral links are regarded as ideal templates of DNA polyhedra. In this research, we introduce odd-half turn edges and pseudo-surrounded vertexes to build DNA polyhedral links and reduce the strands number of them to one or two...

The properties of Cu ions in dealuminated faujasite-type zeolites (Si/Al = 31) containing 1, 2, and 5 wt.% of Cu were investigated by IR spectroscopy with CO and NO as probe molecules. Cu was introduced by impregnation into zeolites in both protonic (HFAU) and sodium (NaFAU) forms of zeolite. Four kinds of Cu species were found: Cu+ exch. , Cu+ oxide , Cu2+ exch. (square, planar, and square pyramidal), and Cu2+ oxide (CuO). The proportions between these four kinds of Cu depended on the amount of Cu and on the form of zeolite to which Cu was introduced (HFAU or NaFAU)...

Background: Rousettus amplexicaudatus is one of the old world fruit bats, commonly known in Javanese word as codot belongs to Order Chiroptera and suborder Megachiroptera. R. amplexicaudatus possessed an outstanding visual ability, which helps in the process of searching for food. Those activities process and save within the brain involving the learning and memory activities. Learning and memory activities are centered around the hippocampus with the help of serotonergic nerve. Aim: This study conducted to identify the morphology and distribution of serotonergic nerve (5-hydroxytryptamine) in the hippocampus of R...

Two major uses of linear perspective are in planar paintings-the flat canvas is incongruent with the painted 3-D scene-and in forced perspectives, such as theater stages that are concave truncated pyramids, where the physical geometry and the depicted scene are congruent. Patrick Hughes pioneered a third major art form, the reverse perspective, where the depicted scene opposes the physical geometry. Reverse perspectives comprise solid forms composed of multiple planar surfaces (truncated pyramids and prisms) jutting toward the viewer, thus forming concave spaces between the solids...

In some cold-adapted organisms, over a dozen isoforms of antifreeze (glyco)proteins or AF(G)Ps are present. Although these isoforms are structurally similar, their ability to inhibit ice growth varies significantly, and in some fish, passive isoforms can be much more abundant than the active ones. Laboratory experiments demonstrated more than a decade ago that mixtures of AFP isoforms can exhibit synergistic enhancement of each other's activity. The mechanism of this synergy effect has remained obscure and is addressed here...

Two polymorphs of tripotassium erbium disilicate, K3 ErSi2 O7 , were synthesized by high-temperature flux crystal growth during the exploration of the flux technique for growing new alkali rare-earth elements (REE) containing silicates. Their crystal structures were determined by single-crystal X-ray diffraction analysis. One of them (denoted 1) crystallizes in the space group P63 /mmc and is isostructural with disilicates K3 LuSi2 O7 , K3 ScSi2 O7 and K3 YSi2 O7 , while the other (denoted 2) crystallizes in the space group P63 /mcm and is isostructural with disilicates K3 NdSi2 O7 , K3 REESi2 O7 (REE = Gd-Yb), K3 YSi2 O7 , K3 (Y0...

During typical early-stage embryo development, single-cell-thick tissues of tightly bound epithelial cells autonomously generate profound changes in their shape, forming the basis of organism anatomy. We report on a (covariant) active-hydrodynamic theory of such monolayer morphogenesis that is closed under its shape-changing dynamics-i.e., the degrees of freedom that encode monolayer geometry appear properly as broken-symmetry variables. In our theory, the salient physics of tissue-scale deformations emerges from a balance between the displacement and/or shear of a low-Reynolds-number embedding fluid (the "yolk") and cell-autonomous stresses, themselves a result of combining apical contractile stresses with an elastic-like mechanical response under the constraint of constant cell volume...

The hydro-thermal synthesis and crystal structure of the simple inorganic compound CaHPO3 , which crystallizes in the chiral space group P 43 21 2, are reported. The structure is built up from distorted CaO7 capped trigonal prisms and HPO3 pseudo pyramids, which share corners and edges to generate a three-dimensional network.

An adaptive optics fundus camera has been developed that uses simultaneous capture of multiple images via adjacent pupil sectors to provide directional sensitivity. In the chosen realization, a shallow refractive pyramid prism is used to subdivide backscattered light from the retina into four solid angles. Parafoveal fundus images have been captured for the eyes of three healthy subjects and directional scattering has been determined using horizontal and vertical differentials. The results for the photoreceptor cones, blood vessels, and the optic disc are discussed...

The reaction of the Mannich base ligand (H2 L = N, N'-dimethyl- N, N'-bis(2-hydroxy-3-methoxy-5-methylbenzyl)ethylenediamine) with Co(OAc)2 ·4H2 O and Ln(III) nitrate salts (Ln = Gd, Tb, and Dy) under basic conditions afforded three carbonato-bridged isostructural tetranuclear heterometallic Co(II)-Ln(III) complexes (Co2 Gd2 L2 (μ4 -CO3 )2 (NO3 )2 ] (1), [Co2 Tb2 L2 (μ4 -CO3 )2 (NO3 )2 ] (2), and [Co2 Dy2 L2 (μ4 -CO3 )2 (NO3 )2 ] (3)) by atmospheric CO2 fixation. In all structures, two dinuclear [(CoII L)LnIII (NO3 )] units are linked via two μ4 -carbonato groups to form the tetranuclear CoII 2 LnIII 2 core...