Ladder-shaped Structure Research Articles

Multilayer Black Phosphorus Exfoliated with the Aid of Sodium Hydroxide: An Improvement in Electrochemical Energy Storage

We generated multilayer black phosphorus (MBP) as a precipitate in centrifugation under 3000 rpm for 25 min, preceded by liquid exfoliation, in which saturated sodium hydroxide (NaOH(s)) was added as an exfoliation auxiliary. The MBP exfoliated with NaOH(s) was characterized by scanning electron microscope, energy dispersive x-ray detector, x-ray diffraction, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Its electrochemical performance was investigated by cyclic voltammetry, charge/discharge and electrochemical impedance spectroscopy. It was found that the appropriate amount of NaOH(s) can make MBP present a ladder-shaped structure or plackets on the layer edge, which may provide more active sites and channels for charge storage to improve its electrochemical performance. The specific capacitance of MBP samples exfoliated with appropriate amounts of NaOH(s) can quickly enter a relatively stable range of 110–90 F/g after the 75th cycle, and finally stabilize at about 90 F/g after thousands of cycles under the current density of 2 A/g, which demonstrates their good stability in the range of long charge/discharge cycles. MBP exhibits double-layer capacitance properties.

Design of a wideband reflective linear polarization converter based on the ladder-shaped structure metasurface

In this paper, a ladder-shaped structure metasurface is proposed and investigated theoretically and experimentally, which can efficiently convert a linear polarized electromagnetic (EM) wave to its orthogonal component in a wideband range. The wideband reflective polarization convertibility is resulted from three resonance modes generated by the ladder-shaped structure MM for the normal incident waves. The mechanism of high-efficiency reflective polarization conversion is illustrated by surface current distribution and the destructive interference theory. The experimental measurement results show that the average polarization conversion ratio (PCR) is greater than 90% from 6.9 to 15.4GHz, which are in good agreement with the numerical simulations and theoretical predictions. The designed metasurface possesses the merits of wideband and high-efficiency, and thus has great application values in novel polarization-control devices.

Iterative calculus on tangent floors

Abstract Tangent fibrations generate a “multi-floored tower”, while raising from one of its floors to the next one, one practically reiterates the previously performed actions. In this way, the "tower" admits a ladder-shaped structure. Raising to the first floors suffices for iteratively performing the subsequent steps. The paper mainly studies the tangent functor. We describe the structure of multiple vector bundle which naturally appears on the floors, tangent maps, sector-forms, the lift of vector fields to upper floors. Further, we show how tangent groups of Lie groups lead to gauge theory, and explain in this context the meaning of covariant differentiation. Finally, we will point out within the floors special subbundles - the osculating bundles, which play an essential role in classical theories.

Structural Basis for Polymer Packing and Solvation Properties of the Organogermanium Crystalline Polymer Propagermanium and Its Derivatives

Of organogermanium compounds known to have an immunostimulatory action, propagermanium [PGe; 3-oxygermylpropionic acid polymer, (C3 H5 GeO3.5 )n] is the only one used as a pharmaceutical agent, to treat the hepatitis B virus in Japan. However, because of lack of information about its structure, PGe has been confused with a polymeric solid, repagermanium (RGe, Ge-132, poly-trans-[(2-carboxyethyl) germasesquioxane], (C18 H30 Ge6 O21 )n), which has the same essential formula as PGe. To clarify this issue, the structure of PGe was analyzed using X-ray diffraction (XRD). PGe has a polymeric ladder-shaped structure of a concatenated eight-membered ring composed of Ge-O bonds, which is clearly distinguished from the infinite sheet structure in RGe. Moreover, we observed temperature or moisture-dependent transformations among these compounds using powder XRD. For instance, PGe was easily dissolved in water, and transformed to RGe by exposure to water vapor, but transformed into another straight-chain structure when exposed to aqueous solution. As a result of these findings, PGe was indicated to have labile polymer packing against RGe. These characteristics of PGe may affect pharmaceutical properties such as respective stability and solubility, which indicate its unique impact on physiological activity.

Exploratory syntheses, structures, and photoluminescent properties of three lead multi-dimensional frameworks

Three structurally diverse PbII coordination complexes, [Pb3O(OH)(4-sphth)]2(H2O) (1), [Pb(3,5-Hdhb)]H2O (2), and [Pb3(4-nphth)2(OH)2] (3) (4-H3sphth, 4-sulfophthalic acid; 3,5-H2dhb, 3,5-dihydroxybenzoic acid; 4-H2nphth, 4-nitrophthalic acid), were synthesized under hydrothermal conditions. X-ray diffraction analyses reveal that 1 is constructed from [Pb4O4] cubanes, based on which ladder-shaped structure is built via 4-H3sphth bridge. This is the first Pb4O4-containing polymer. The Pb2O2 units in 2 are bridged by two parallel 3,5-HDHB ligands along the a-axis and two other parallel 3,5-HDHB ligands along the b-axis, forming a 3-D framework. For 3, the crystal structure is built up of a layer motif consisting of corner-sharing pyramidal Pb3O units, which are linked through Pb corners to form a hexagonal unit. Each PbO6 polyhedron is connected to three polyhedra (Pb3O) via sharing an edge (two μ 3-oxygen atoms) and two faces (three μ 3-oxygen atoms), thus yielding an infinite 2-D Pb–O–Pb (3,6-net) honeycomb layer. The luminescence of 1–3 demonstrates that they may be good candidates for luminescent materials.

Synthesis and crystal structures of three new complexes derived from 3-(pyridin-3′-yl)-5-(pyridin-2′′-yl)-1,2,4-triazole

Three new coordination complexes, [Cd2(ppt)2(cpba)] · (H2O)2 (1), [Zn(ppt)2] · (H2O) (2), and [Zn(MoO4)(Hppt)] (3) (H2cpba: 3-(2′-carboxy-phenoxy)-benzoic acid; Hppt: 3-(pyridin-3′-yl)-5-(pyridin-2′′-yl)-1,2,4-triazole), were synthesized under hydrothermal conditions. Their structures have been determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric analyses. X-ray diffraction analyses revealed that Cd(II) ions are linked by ppt− to form a ladder-shaped structure along the a-axis and further displays a 2-D supramolecular architecture with cpba2− along the c-axis. In 2, each Zn(ppt)2 fragment is linked by the nitrogen of pyridin-3′-yl from the neighboring Zn(ppt)2 forming a V-shaped chain. Compound 3 consists of a ladder structure, in which each {MoO4} unit is a bridge linking three Zn(Hppt)2+ fragments.

Investigation of the influence of structural parameters of a Fresnel-type lens on the narrowing of light-emitting diode light beams

In this study, an influence of the structural parameters of a three-dimensional (3D)-Fresnel-based lens which was designed as a primary optic on the narrowing of light-emitting diode (LED) light beams has been investigated and proposed to gather the emitted light into a narrow-angle light beam. Most conventional LEDs are not able to create a narrow-angle light beam without using a reflector cup or secondary optics, because the LED lighting angle is usually wide (±30 deg from the centerline of the light source). Nevertheless, the energy of the LED light within the range ±16 deg from the centerline of the light source can be greatly enhanced by the focusing effect of a 3D-Fresnel-based lens design as shown in this study. The illumination and the luminous flux of the LED light beam in comparison with the conventional LED have been respectively enhanced up to 61% and 20% respectively. The main contribution of this study is to adjust the height/width ratio of the ladder-shaped structure of a 3D-Fresnel-based lens in order to focus the LED light into a stronger beam, and to meet some specific working circumstances.

Synthesis, Structure and Fluorescence Properties of a Coordination Polymer [Cu2(SCN)4(BPX)]n with 1D Ladder-Shaped Structure

A coordination polymer, [Cu2(SCN)4(BPX)]n(BPX = 1,4-bis(pyridinium) xylol) was synthesized and characterized by IR spectrum, fluorescence spectrum and single crystal X-ray diffraction. Crystal structure revealed that the title compound crystallized in monoclinic system with space group P2(1)/c, a = 5.7540(7)Å, b = 12.7203(15) Å, c = 17.598(2) Å, β = 94.9940(10)°. Two SCN−ions served as bridging ligands to link two Cu(I) ions, giving rise to an eight-member ring. Furthermore, copper atom and sulfur atom of the eight-member ring bonded sulfur atom and copper atom of adjacent eight-member ring through the formation of Cu-S to form a small four-member ring. Thus, innumerable eight-member rings alternately linked four-member rings each other to form an infinite one-dimensional ladder-shaped structure.

An Improved Performance Poly-Si Pirani Vacuum Gauge Using Heat-Distributing Structural Supports

A new micro-Pirani vacuum gauge that employs a ladder-shaped structure with two parallel bridges and crosslinks in between has been designed and fabricated. This design enhances the physical performance of the gauge by increasing structural rigidity, thus allowing for longer beams and a wider selection of materials, and by allowing for better heat distribution across the sensor - therefore improving the full-scale range of sensor response. Furthermore, this Pirani gauge can be fabricated in a one-, two-, or three-mask process without postprocessing steps such as KOH etching. In a CMOS-compatible process, poly-Si 4 times 2 times 250-mum and 4 times 2 times 1000-mum Pirani gauges with the ladder structure were fabricated and tested with pressure ranges from 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> to 50 torr (0.133 to 1 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> Pa) and 5 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> to 760 torr (6.67 to 1.01 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> -Pa atmospheric pressure) and with resolutions of approximately 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> and 5 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> (0.133 to 6.67 Pa), respectively. Constant temperature circuitry and thermoelectric temperature stabilization would further extend the range of operation and the resolution of these devices. Furthermore, these sensors operate at very low powers ranging from 300 to 600 muW depending on their geometry and pressure measurement range.