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Pyramid prism

Sandipan Chakraborty, Biman Jana
Ice recognition by antifreeze proteins (AFPs) is a subject of topical interest. Among several classes of AFPs, insect AFPs are hyperactive presumably due to their ability to adsorb on basal plane. However, the origin of the basal plane binding specificity is not clearly known. Present work aims to provide atomistic insight into the origin of basal plane recognition by an insect antifreeze protein. Free energy calculations reveal that the order of binding affinity of the AFP towards different ice planes is: basal plane > prism plane > pyramidal plane...
March 6, 2018: Journal of Physical Chemistry. B
Fabio Lapenta, Jana Aupič, Žiga Strmšek, Roman Jerala
The design of new protein folds represents a grand challenge for synthetic, chemical and structural biology. Due to the good understanding of the principles governing its pairing specificity, coiled coil (CC) peptide secondary structure elements can be exploited for the construction of modular protein assemblies acting as a proxy for the straightforward complementarity of DNA modules. The prerequisite for the successful translation of the modular assembly strategy pioneered by DNA nanotechnology to protein design is the availability of orthogonal building modules: a collection of peptides that assemble into CCs only with their predetermined partners...
February 5, 2018: Chemical Society Reviews
Eike M Langer, Olaf Walter, Jean-Yves Colle, Dirk Bosbach, Evgeny V Alekseev
A study of neptunium (Np) chemistry in the complex oxo-selenium system has been performed. Hereby, two sets of precipitation experiments were conducted, investigating the influence of the initial oxidation state of selenium using SeIVO2 and H2SeVIO4 with NpV in alkali nitrate solution, keeping the ratio of Np/Se constant. Surprising results were observed. Five novel neptunium and selenium bearing compounds have been obtained by slow evaporation from aqueous solution. The novel NpIV phase K4-x[Np(SeO3)4-x(HSeO3)x]·(H2O)1...
January 22, 2018: Inorganic Chemistry
Ajasja Ljubetič, Fabio Lapenta, Helena Gradišar, Igor Drobnak, Jana Aupič, Žiga Strmšek, Duško Lainšček, Iva Hafner-Bratkovič, Andreja Majerle, Nuša Krivec, Mojca Benčina, Tomaž Pisanski, Tanja Ćirković Veličković, Adam Round, José María Carazo, Roberto Melero, Roman Jerala
Polypeptides and polynucleotides are natural programmable biopolymers that can self-assemble into complex tertiary structures. We describe a system analogous to designed DNA nanostructures in which protein coiled-coil (CC) dimers serve as building blocks for modular de novo design of polyhedral protein cages that efficiently self-assemble in vitro and in vivo. We produced and characterized >20 single-chain protein cages in three shapes-tetrahedron, four-sided pyramid, and triangular prism-with the largest containing >700 amino-acid residues and measuring 11 nm in diameter...
November 2017: Nature Biotechnology
Qiaoyue Xi, Ge Gao, Hua Zhou, Yongxia Zhao, Cunqi Wu, Lidan Wang, Pengran Guo, Jingwei Xu
In this work, three different CuSCN nanostructures (NSs), hexagonal prism-like (3D), pyramid-like (2D) and nanowire structures (NWs) are first applied to inverted heterojunction perovskite solar cells as p-type inorganic hole transport layers (HTLs) using a moderate electrodeposition method at room temperature. It is revealed that the crystal structure and the thickness of the CuSCN layer can dramatically regulate the morphology and the crystal orientation behavior of perovskite absorbing layers, which will further have a significant influence on the following device performance...
May 11, 2017: Nanoscale
Morgane Poupon, Nicolas Barrier, Sébastien Petit, Sophie Boudin
A new β-CdTeO3 polymorph was obtained by hydrothermal synthesis and its structure was solved ab initio from powder X-ray diffraction data. It appears that the structure of β-CdTeO3 (Pnma, Z = 16, a = 7.45850(3) Å, b = 14.52185(6) Å, c = 11.04584(5) Å) is closely related to that of α-CdTeO3 (P21/c, Z = 8, a = 7.790(1) Å, b = 11.253(2) Å, c = 7.418(1) Å, β = 113.5(1)°) previously reported. The 3D framework of β-CdTeO3 is built of both [CdO6] distorted octahedra and [CdO7] mono-capped trigonal prisms and three different tellurium polyhedra: trigonal pyramids [Te(IV)O3E] and trigonal bipyramids [Te(IV)O4E] and [Te(IV)O3+1E] (E denotes the lone pair of Te(IV))...
January 23, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Amit Chakraborty, Joydeb Goura, Prasenjit Bag, Arun Kumar Bar, Jean-Pascal Sutter, Vadapalli Chandrasekhar
Utilizing a new ferrocene-based compartmental ligand, H4L (1), a series of novel heterometallic complexes [{LZn(μ-OAc)Dy}4(μ4-H2O)] (2), [{LZn(μ-OAc)Tb}4(μ4-H2O)] (3), [{LZn(μ-OAc)Ho}4(μ4-H2O)] (4), [L = Fe[(C5H4){-C(Me)[double bond, length as m-dash]N-N[double bond, length as m-dash]C6H3-(o-O)(m-O)}]2] were synthesized and characterized. 2 and 3 crystallize in the monoclinic crystal system in the I2/m space group, whereas 4 crystallizes in the tetragonal crystal system in the I4/m space group. The tetra deprotonated ligand L(4-) has two distinct coordination compartments: one pocket (2N, 2O) suitable for the transition metal (3d) ions and another pocket (4O) suitable for lanthanide (4f) metal ions...
October 17, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Sanghyuk Wooh, Soojin Lee, Yunchan Lee, Ji Ho Ryu, Won Bo Lee, Hyunsik Yoon, Kookheon Char
Cracks observed in brittle materials are mostly regarded as defects or failures. However, they can be a valuable tool when implemented in a controlled way. Here, we introduce a strategy to control the crack propagation of mesoporous micro-patterns (prisms and pyramids), which leads to the isolation of well-defined micro-structures. Mesoporous micro-patterns were fabricated by the soft imprinting technique with wet TiO2 nanoparticle (NP) pastes, followed by sintering to remove organic components. Since the volume of the paste significantly shrinks during the sintering step, stress is localized at the edge of micro-patterns, in good agreement with the FEM simulations, creating well-defined cracks and their propagation...
September 12, 2016: ACS Nano
Hyemin Lee, Hyein Seo, Sunghwan Kang, Hyunsik Yoon
We propose a new concept of separating images through a directional guide of multi-visuals by using structured prism or pyramid arrays. By placing prism arrays onto two different image arrays, the two collective images below the facets are guided to different directions. Using optical calculations, we identify a condition for successful image separation. Transparent pyramid arrays are used to separate four images into four directions. The direction of refracted rays can be controlled by the refractive index of prisms and liquid filled into the voids...
September 5, 2016: Optics Express
Sun Woo Kim, Thomas J Emge, Martha Greenblatt
Vanadium tellurites display a rich structural chemistry with interesting physical properties, such as second harmonic generation (SHG). Tellurites, i.e. Te(4+)Ox, are often observed in unusual structures and form various structural motifs, including isolated clusters, chains, layers, and three-dimensional networks. Similarly, vanadates, i.e. V(5+)Ox, show rich structural features, such as VO4 tetrahedra, VO5 square pyramids or trigonal bipyramids, and VO6 octahedra. Strontium vanadium tellurite, Sr7V4Te12O41, was obtained from the melt of the solid-state reaction of SrTeO4 and VO2 in a sealed quartz tube as it cooled from 973 K...
August 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Michael Mayrhofer-Reinhartshuber, Helmut Ahammer
Fractal analysis (FA) should be able to yield reliable and fast results for high-resolution digital images to be applicable in fields that require immediate outcomes. Triggered by an efficient implementation of FA for binary images, we present three new approaches for fractal dimension (D) estimation of images that utilize image pyramids, namely, the pyramid triangular prism, the pyramid gradient, and the pyramid differences method (PTPM, PGM, PDM). We evaluated the performance of the three new and five standard techniques when applied to images with sizes up to 8192 × 8192 pixels...
July 2016: Chaos
Jin-Rui Ding, Kyo-Seon Kim
Tungsten oxide thin films have been found as an active visible light driven photoanode material for photoelectrochemical water splitting due to its good stability in aqueous solution and energetically favorable valence band position for water oxidation. Morphology control, which determines the performance of WO3 photoanode, is one of most focuses of recent research interests. In this work, we successfully prepared monoclinic WO3 thin films on ITO glass at low range of substrate temperature with a fabrication rate around 100 nm per minute by using aerosol flame deposition process...
February 2016: Journal of Nanoscience and Nanotechnology
N Matthaiakakis, H Mizuta, M D B Charlton
An optical device configuration allowing efficient electrical tuning of surface plasmon wavelength and absorption in a suspended/conformal graphene film is reported. An underlying 2-dimensional array of inverted rectangular pyramids greatly enhances optical coupling to the graphene film. In contrast to devices utilising 1D grating or Kretchman prism coupling configurations, both s and p polarization can excite plasmons due to symmetry of the grating structure. Additionally, the excited high frequency plasmon mode has a wavelength independent of incident photon angle allowing multidirectional coupling...
2016: Scientific Reports
Jenna W J Wu, Ryoichi Moriyama, Hiroshi Tahara, Keijiro Ohshimo, Fuminori Misaizu
Stable compositions and geometrical structures of vanadium oxide cluster ions, VmOn(±), were investigated by ion mobility mass spectrometry (IM-MS). The most stable compositions of vanadium oxide cluster cations were (V2O4)(V2O5)(m-2)/2(+) and (VO2)(V2O5)(m-1)/2(+), depending on the clusters with even and odd numbers of vanadium atoms. Compositions one-oxygen richer than the cations, such as (V2O5)m/2(-) and (VO3)(V2O5)(m-1)/2(-), were predominantly observed for cluster anions. Assignments of these stable cluster ion compositions, which were determined as a result of collision-induced dissociations in IM-MS, can partly be explained with consideration of spin density distribution...
June 2, 2016: Journal of Physical Chemistry. A
Gangsheng Zhang
UNLABELLED: Nacre has long served as a model for understanding the biomineralization process and designing bio-inspired materials. However, our current knowledge about nacre is essentially based on the investigation of the flat nacre, where its building blocks, the aragonite tablets, grow on the flat substrate. Here, using field-emission scanning (SEM) and transmission electron microscopy (TEM), we investigate a new type of nacre, where the tablets grow on the wavy substrate. We first show that: (1) with growth, the tablet undergoes a shape transition from a pyramid to a frustum and finally to a dome-capped prism; (2) the shape transition occurs earlier at the downslope side of the tablet than at the upslope due to the slope effect; and (3) the shape of the top and base facet of the mature tablet depends on that of the substrate surface...
May 2016: Acta Biomaterialia
Oksana Sologub, Leonid Salamakha, Peter Rogl, Berthold Stöger, Ernst Bauer, Johannes Bernardi, Gerald Giester, Monika Waas, Robert Svagera
On the basis of a detailed study applying X-ray single-crystal and powder diffraction, differential scanning calorimetry, and scanning electron microscopy analysis, it was possible to resolve existing uncertainties in the Pt-rich section (≥65 atom % Pt) of the binary Pt-B phase diagram above 600 °C. The formation of a unique structure has been observed for Pt2B [X-ray single-crystal data: space group C2/m, a = 1.62717(11) nm, b = 0.32788(2) nm, c = 0.44200(3) nm, β = 104.401(4)°, RF2 = 0.030]. Within the homogeneity range of "Pt3B", X-ray powder diffraction phase analysis prompted two structural modifications as a function of temperature...
November 16, 2015: Inorganic Chemistry
Tianjun Sun, Sherry Y Gauthier, Robert L Campbell, Peter L Davies
Antifreeze proteins (AFPs) adsorb to ice through an extensive, flat, relatively hydrophobic surface. It has been suggested that this ice-binding site (IBS) organizes surface waters into an ice-like clathrate arrangement that matches and fuses to the quasi-liquid layer on the ice surface. On cooling, these waters join the ice lattice and freeze the AFP to its ligand. Evidence for the generality of this binding mechanism is limited because AFPs tend to crystallize with their IBS as a preferred protein-protein contact surface, which displaces some bound waters...
October 8, 2015: Journal of Physical Chemistry. B
Adrian M V Brânzanic, Alexandru Lupan, R Bruce King
The structures of five-vertex dimetallaboranes Cp2M2B3H7 (Cp = η(5)-C5H5) of the second and third row transition metals, including the experimentally known Cp*2Rh2B3H7 (Cp* = η(5)-Me5C5), have been investigated by density functional theory. The predicted low-energy structures for Cp2M2B3H7 (M = Rh, Ir) are tetragonal pyramids similar to Cp*2Rh2B3H7 and pentaborane-9 B5H9 and consistent with their 14 Wadean skeletal electrons. Two Cp*2Rh2B3H7 structures with the same central Rh2B3 tetragonal prism are found with energies within ∼1 kcal mol(-1) of each other, consistent with the experimental observation of two isomers in solution...
April 28, 2015: Dalton Transactions: An International Journal of Inorganic Chemistry
Krishna K Ramachandran, Stanislav S Stoyko, C Scott Mullen, Arthur Mar
The quaternary rare-earth phosphides REMnCu(4)P(3) (RE = Gd-Ho) were obtained from direct reactions of the elements at 800 °C. They are the first examples in which ordering of two different transition-metal atoms takes place within the orthorhombic YCo(5)P(3)-type structure [Pearson symbol oP36, space group Pnma, Z = 4; a = 12.667(2)-12.6489(4) Å, b = 3.8119(7)-3.7755(1) Å, and c = 10.895(2)-10.8632(4) Å for RE = Gd-Ho]. Columns of trigonal prisms centered by P atoms are connected in propellor-shaped units in zigzag arrangements to generate square-pyramidal (CN5) sites that are occupied by Mn atoms and tetrahedral sites (CN4) that are occupied by Cu atoms...
February 2, 2015: Inorganic Chemistry
Ute Friedrich, Nikolaus Korber
The title compound, penta-caesium nona-stannide hydroxide tetra-ammonia, crystallized from a solution of CsSnBi in liquid ammonia. The Sn9 (4-) unit forms a monocapped quadratic anti-prism. The hydroxide ion is surrounded by five caesium cations, which form a distorted quadratic pyramidal polyhedron. A three-dimensional network is formed by Cs-Sn [3.8881 (7) Å to 4.5284 (7) Å] and Cs-NH3 [3.276 (7)-3.636 (7) Å] contacts.
June 1, 2014: Acta Crystallographica. Section E, Structure Reports Online
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