Hexagonal Disks Research Articles

Dynamics of wet granular hexagons.

The collective behavior of vibrated hexagonal disks confined in a monolayer is investigated experimentally. Due to the broken circular symmetry, hexagons prefer to rotate upon sufficiently strong driving. Due to the formation of liquid bridges, short-ranged cohesive interactions are introduced upon wetting. Consequently, a nonequilibrium stationary state with the rotating disks self-organized in a hexagonal structure arises. The bond length of the hexagonal structure is slightly smaller than the circumdiameter of a hexagon, indicating geometric frustration. This investigation provides an example where the collective behavior of granular matter is tuned by the shape of individual particles.

Direct Synthesis of Nanofluids Containing Novel Hexagonal Disc Shaped Copper Nanoparticles

Direct Synthesis of Nanofluids Containing Novel Hexagonal Disc Shaped Copper Nanoparticles

Hexagonal Disk Structures Obtained during Carbonization of <i>Botryococcus braunii</i> Residues

In this study, we report a two-dimensional (2D) hexagonal disk obtained by carbonization of Botryococcus braunii (B. braunii) residues. Carbonization at 700℃followed by naturally cooling down to room temperature under a non-inert gas flow atmosphere affords to yield this unique structure. The 2D hexagonal disks consist of more than 52% carbon and more than 25% oxygen. Slight amount of Fe, silicon and magnesium would be the trigger of the formation of hexagonal structure. Treatment of biomass residue is a challenge in the near future accompanied by the achievement of new energy technology in the industrial level. This research points out that efficient use of discharged biomass residue could create a new avenue for material science. The morphology of obtained crystals carbonized in different conditions, especially with the existence of argon flow, was also investigated.

Synthesis, optical properties, and energy transfer of Ce3+, Tb3+ doped KLu2F7

Ce3+, Tb3+ doped orthorhombic phases of KLu2F7 microcrystals with hexagonal disk morphology were synthesized by a hydrothermal method. Enhanced emissions of Tb3+ were observed in the Ce3+/Tb3+ co-doped KLu2F7 sample compared to the Tb3+ single-doped KLu2F7. The energy transfer efficiency from Ce3+ to Tb3+ was calculated by the photoluminescence intensity in the Ce3+/Tb3+ co-doped KLu2F7 samples. The average separations between Ce3+ and Tb3+ were calculated and the critical distance was 0.922 nm estimated by method of concentration quenching. The theoretical calculation proved the results. The theoretical analysis also suggested that the energy transfer from Ce3+ to Tb3+ in the KLu2F7 occurred predominantly via the dipole-quadrupole interaction. The KLu2F7 should be good host materials for emitters.

Hydrothermally grown ZnO nanoparticles for effective photocatalytic activity

ZnO nanoparticles were prepared by hydrothermal method from the source materials of zinc chloride and ammonium hydroxide. Precursor solution pH was varied to 7, 9, 11 and 13 by the addition of ammonium solution and the solution was hydrothermally treated at 150°C for 3h. Further prepared samples were annealed at 400°C for 3h. X-ray diffraction technique was employed to study the structure and crystalline nature of synthesized nanoparticles. Diffuse Reflectance Spectroscopy studies revealed that optical band gap of ZnO is slightly varied due to the effect of size of the particle. Field emission scanning electron microscope images showed that the prepared ZnO nanoparticles acquired spindle like nanorods, hexagonal disk, porous nanorods and nanoflower structures due to the effect of pH of the precursor solution. Photocatlytic activity of the prepared ZnO nanoparticles was evaluated for Rhodamine B (RhB) dye which showed 94% of degradation and good stability for five cycles.

Investigation of morphologies, photoluminescence and photocatalytic properties of ZnO nanostructures fabricated using different basic ionic liquids

ZnO nanostructures were synthesized in methanol-water reaction media using different basic ionic liquids [BILs] by hydrothermal approach at 150°C. ZnO nanoparticles obtained from BILs consists of different morphologies, such as, hexagonal disks, hexagonal rings assembled by nanoparticles, hexagonal disks-aggregated flower-like structure and nanospheres. The effect of these basic ionic liquids on morphology, particle size and properties of as-synthesized ZnO nanostructures was investigated. The obtained nanoparticles have been characterized by X-ray diffraction, TEM, SEM, UV–vis absorption spectroscopy and photoluminescence (PL) studies. The XRD study of as-synthesized ZnO nanostructures confirmed the existence of hexagonal wurtzite structure. The maximum around 371nm was observed in UV–vis absorption spectrum and the calculated band-gap energy is in the range of 3.07-3.10eV. The photoluminescence spectra exhibited blue and blue-green emissions. ZnO nanoparticles prepared in choline hydroxide showed higher photocatalytic activity, which was accounted for due to high surface area, the smaller size of nanoparticles and low electron-hole recombination effect.

Tuning the Phase and Shape of Copper Sulfide Nanostructures Using Mixed Solvent Systems

AbstractPhase pure copper sulfide nanoparticles with various shapes and superlattices were synthesized using Bis(O‐isobutyldithiocarbonato)copper(II) complex as single source precursor (SSP) by the hot injection method. Optimization of reaction conditions provide mono‐disperse nanospheres, nanorods, hexagonal disks and cubic nanoparticles. Furthermore, self‐assembly of highly monodispersed nanoarrays were also obtained by tuning reaction parameters. The kinetics of decomposition of the SSP under the influence of activating and/or stabilizing agents is discussed.

Hydrothermal synthesis of β-Co(OH)2 nanoplatelets: A novel catalyst for CO oxidation

A facile, cost-effective, template-free chemical method was developed for the synthesis of β-Co(OH)2 nanoplatelets under the different preparation conditions. The morphology and microstructure of as-synthesized samples were examined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS), respectively. The observations revealed the formation of a single phase of the hexagonal brucite-like β-Co(OH)2, which had an irregular hexagonal disk with angles of adjacent edges of 120°, edge lengths ranging from 200 to 300nm, and thicknesses of 20–40nm. When investigated as catalyst for CO oxidation, the β-Co(OH)2 nanoplatelets exhibited good catalytic activity for CO. Among β-Co(OH)2 nanoplatelets, the sample prepared at 100°C for 8h performed the best, giving the T100% (the temperature required for achieving a CO of 100%) of 120°C for the oxidation of CO. There are good correlations of Co3+/Co2+, the absorbed Ox− ions and surface OH group with catalytic activity of the samples for CO oxidation.

Synthesis of Hexagonal ZnO-PQ7 Nano Disks Conjugated with Folic Acid to Image MCF - 7 Cancer Cells.

Surface modified ZnO nanomaterial is widely used in the field of bioimaging worldwide due to its optical properties, electronic characteristics and biocompatibility. Fluorescent enhanced, Polyquaternium-7(PQ7) capped, ZnO hexagonal nano disks (ZnO-PQ7) were synthesised by simple wet chemical method. The structural and optical properties of ZnO-PQ7 hexagonal nano disks were characterized using XRD, UV-Visible, Fluorescence, HRTEM, EDAX and FTIR studies. The size of synthesised ZnO-PQ7 were around 30-45nm asconfirmed by HRTEM studies. Fluorescence emission intensity increased with increase in PQ7 concentration. ZnO-PQ7 was further conjugated with folic acid (FA) to target human breast cancer cell line (MCF-7) via EDC/NHS coupling chemistry. Conjugation of folic acid with ZnO-PQ7 was confirmed by FTIR studies. The cell viability study using Methyl thiazolyltetrazolium(MTT) assay has demonstrated that the ZnO-PQ7 conjugated FA composites (ZnO-PQ7-FA) exhibit low toxicity towards MCF-7 up to a concentration of 125μg/mL. Confocal laser scanning microscopic images confirmed the uptake of ZnO-PQ7-FA nanoparticles by MCF-7 cells. This study reveals ZnO-PQ7-FA nano disks as a potential imaging agent for detection of cancer cells. The synthesis route reported in this article is simple and easy to follow for the synthesis of ZnO-PQ7-FA in bulk quantities with high purity.

Accessing Three-Dimensional Crystals with Incorporated Guests through Metal-Directed Coiled-Coil Peptide Assembly.

Obtaining three-dimensional (3D) protein and peptide crystals on demand requires a precisely orchestrated hierarchical assembly of biopolymer building blocks. In this work, we disclose a metal-ion-mediated strategy to assemble trimeric coiled-coil peptides in a head-to-tail fashion into linear strands with interstrand interactions. This design led to hexagonal 3D peptide crystal formation within 30 min in the presence of divalent metal ions. The crystal morphology could be controlled by varying the metal ion/peptide ratio, resulting in hexagonal discs to rods. Diffraction studies elucidated the head-to-tail arrangement of the coiled-coil linear strands and their hexagonal, antiparallel packing within the crystal. Unsatisfied ligands at the hexagonal ends of the crystals were harnessed as a powerful means to direct His-tagged fluorophores to distinct locations within the crystals. Overall, the designed hierarchical assembly provides a facile means to obtain 3D peptide crystals and incorporate His-tag-based cargoes and may have potential use in drug delivery and sensor design.

Influence of the shape of disk knife on the pinching of material

During the primary cultivation by means of general-purpose ploughs, the circular disk knives do not provide a reliable cutting; with that, the traction resistance of plough is increased, productivity and quality of its work are reduced. The purpose of the research is to increase the operational efficiency, the quality of soil cultivation and to reduce the energy intensity of general-purpose ploughs equipped with disc knives. Different designs of knives are studied in order to find the optimal shape providing a reliable pinching of plant and straw mass. A formula for determining the angle of pinching of a polygonal disc depending on the cultivation depth and number of angles in the polygon is given. The studies show that the hexagonal disk knives have the minimum angle of pinching, thus this shape is rational. The operating conditions are defined, in which the stalks of straw mass do not slip out of the knife blade when cutting. Motion paths of blades of hexagonal and circular knives at different positions of the instantaneous center of disk rotation are studied graphically. An empirical formula is obtained; dependences of pinching coefficient on the position of instantaneous center of disk rotation are constructed. It is found that with decreasing of nominal diameter of a knife the pinching coefficient is increased, and the quality of pinching of crop materials is improved. As a result of the research, the dependences are obtained showing that the areas of reliable pinching and cutting linearly depend on the kinematic parameter. With the cultivation depth of 0.08-0.12 m, the efficiency of pinching of hexagonal knife is increased by 1.8-2 times compared to the circular one.

Growth of InN hexagonal microdisks

InN hexagonal thin wurtzite disks were grown on γ-LiAlO2 by plasma-assisted molecular-beam epitaxy at low temperature (470oC). The (0001¯) InN thin disk was established with the capture of N atoms by the β¯-dangling bonds of most-outside In atoms, and then the lateral over-growth of the In atoms were caught by the β¯-dangling bonds of the N atoms. From the analyses of high-resolution transmission electron microscopy, the lateral over-grown width was extended to three unit cells at [11¯00]InN direction for a unit step-layer, resulting in an oblique surface with 73o off c-axis.

Spherical Vesicles Formed by Co-Assembly of Cyclic Pentagonal Pillar[5]quinone with Cyclic Hexagonal Pillar[6]arene.

Mixing cyclic pentagonal pillar[5]quinone with cyclic hexagonal pillar[6]arene in a 12:20 molar feed ratio resulted in spontaneous production of vesicles, while assembly of pillar[6]arene and pillar[5]quinone alone produced hexagonal disks and wires, respectively. Incorporation of pentagonal pillar[5]quinone rings into hexagonal pillar[6]arene sheets gave curvature and contributed to the formation of vesicles. Conventional vesicles are generally synthesized by assembly of amphiphilic molecules containing hydrophobic and hydrophilic parts. Therefore, the co-assembly of pentagonal and hexagonal molecules to obtain spherical vesicles demonstrated in this study is a new concept based on geometric design.

Topotactic Transformation Route to Monodisperse β-NaYF4:Ln3+ Microcrystals with Luminescence Properties

A novel nonorganic wet route for direct synthesis of uniform hexagonal β-NaYF4:Ln(3+) (Ln = Eu, Tb, Ce/Tb, Yb/Er, and Yb/Tm) microcrystals with various morphologies has been developed wherein the intermediate routine cubic-hexagonal (α → β) phase transfer process was avoided. The morphology can be effectively tuned into hexagonal disc, prism, and novel hierarchical architectures by systematically fine manipulating the Na2CO3/F(-) feeding ratio. It has been found that the routine α → β phase transfer for NaYF4 was not detected during the growth, while NaY(CO3)F2 emerged in the initial reaction stage and fast transformed into β-NaYF4 via a novel topotactic transformation behavior. Detailed structural analysis showed that β-NaYF4 preferred the [001] epitaxial growth direction of NaY(CO3)F2 due to the structural matching of [001]NaY(CO3)F2//[0001]β-NaYF4. Besides, the potential application of the as-prepared products as phosphors is emphasized by demonstrating multicolor emissions including downconversion, upconversion, and energy transfer (Ce-Tb) process by lanthanides doping.

Research of movement of hexagonal and circular disk working organs of tillage machines

The plough hexagonal disk knife has been theoretically investigated, produced and tested in laboratory soil bin and in field conditions. Using of hexagonal knives instead of standard circular ones allows to reduce the traction resistance of tillage machine and to increase significantly the quality of ploughing.

Ce(3+) /Tb(3+) non-/single-/co-doped K-Lu-F materials: synthesis, optical properties, and energy transfer.

Using a hydrothermal method, Ce(3+) /Tb(3+) non-/single-/co-doped K-Lu-F materials have been synthesized. The X-ray diffraction (XRD) results suggest that the Ce(3+) and/or Tb(3+) doping had great effects on the crystalline phases of the final samples. The field emission scanning electron microscopy (FE-SEM) images indicated that the samples were in hexagonal disk or polyhedron morphologies in addition to some nanoparticles, which also indicated that the doping also had great effects on the sizes and the morphologies of the samples. The energy-dispersive spectroscopy (EDS) patterns illustrated the constituents of different samples. The enhanced emissions of Tb(3+) were observed in the Ce(3+) /Tb(3+) co-doped K-Lu-F materials. The energy transfer (ET) efficiency ηT were calculated based on the fluorescence yield. The ET mechanism from Ce(3+) to Tb(3+) was confirmed to be the dipole-quadrupole interaction inferred from the theoretical analysis and the experimental data. Copyright © 2015 John Wiley & Sons, Ltd.

Role of the vacuum pressure and temperature in the shape of metal Zn nanoparticles

Zinc (Zn) nanoparticles were fabricated by the high-vacuum thermal evapouration technique. The vacuum pressure was modified from 10−6 to 15 Torr and the substrate temperature was increased from room temperature to 100 ∘C in order to evaluate the changes in the morphological and structural characteristics of the Zn nanoparticles. Well-faceted hexagonal disk shaped nanoparticles were formed at a vacuum pressure of 10−6 Torr with the substrate kept at room temperature. Aggregation and surface irregularities at the edges of the hexagonal nanodisks were observed with further increases in the vacuum pressure. The nanoscale characteristics of the nanodisks were lost at a vacuum pressure of 10−6 Torr and heating the substrate at 100 ∘C. The nanodisks were transformed into Zn wires at a vacuum pressure of 15 Torr with a substrate temperature of 100 ∘C. It is suggested that the initial stages of the growth of the Zn wires are governed by the agglomeration of the Zn nanodisks since the structure of the wires was observed to be composed by stacked nanodisks.

Mn doped GaN nanoparticles synthesized by rapid thermal treatment in ammonia

We present a novel route for the synthesis of manganese doped GaN nanoparticles. Nanoparticles in the form of hexagonal discs were synthesized by rapid thermal treatment of manganese doped ammonium hexafluorogallate in ammonium atmosphere. The morphology of GaN:Mn nanoparticles was investigated using scanning electron microscopy. A concentration over 0.7 wt.% of Mn was observed by X-ray fluorescence and electron microprobe. Structural and electronic properties were investigated using X-ray diffraction, Raman spectroscopy and micro-photoluminescence with excitation wavelength of 325 nm and 532 nm. The magnetic properties between 4.5 K and 300 K were investigated by a superconducting quantum interference device (SQUID) magnetometer. GaN:Mn nanoparticles show a purely paramagnetic behavior which can be interpreted in terms of Mn2+ ions exhibiting an antiferromagnetic interaction.

Facile green fabrication of nanostructure ZnO plates, bullets, flower, prismatic tip, closed pine cone: Their antibacterial, antioxidant, photoluminescent and photocatalytic properties

Green synthesis of multifunctional Zinc oxide nanoparticles (NPs) with a variety of morphologies were achieved by low temperature solution combustion route employing neem (Azadirachta indica) extract as fuel. The nanoparticles were characterized by PXRD, FTIR, XPS, Raman and UV–Visible spectroscopic studies. The Morphologies were studied by SEM and TEM analysis. The NPs were subjected for photoluminescence, photocatalytic, antibacterial and antioxidant activity studies. PXRD pattern confirmed the hexagonal wurtzite structure of the product. SEM images indicated the transformation of mushroom like hexagonal disks to bullets, buds, cones, bundles and closed pine cone structured NPs with increase in the concentration of neem extract in reaction mixture. The NPs exhibited prominent green emission due to the presence of intrinsic defect centers. The as-formed bullet shaped ZnO with 4ml of neem extract was found to decolorize Methylene blue (MB) under Sunlight and UV light irradiation. The antibacterial studies indicated that ZnO NPs of concentration 500, 750 and 1000μg resulted in significant antibacterial activity on Klebsiella aerogenes and Staphylococcus aureus but not against Escherichia coli and Pseudomonas aeruginosa in agar well diffusion method. Further, ZnO NPs exhibited significant antioxidant activity against scavenging DPPH free radicals. The current investigation demonstrated green engineering method for the synthesis of multifunctional ZnO NPs with interesting morphologies using neem extract.

Study of Stirrer Disc Structure Type on Grinding Performance of a Horizontal Stirred Mill

The research object is horizontal stirred mill, and I have studied six different Stirrer disc (including the trapezoidal tooth disc, the serrated toothed disc, the common disc, decagonal disc, the octagonal disc and the hexagonal disc) structure on the horizontal stirred mill grinding efficiency. The paper applied EDEM for six different forms of Stirrer disc simulation, analyzing the simulation results, it is concluded that: when the Stirrer disc structure is the trapezoidal tooth disc, the comprehensive performance of horizontal stirred grinding machine is best, with high grinding efficiency, low power consumption, provide a reference for the design of the Horizontal stirred mill.