Hexagonal Research Articles

Morphology and Optical Properties of Zinc Oxide Nanoparticles Synthesized by Solvothermal Method

Zinc oxide (ZnO) nanoparticles were successfully synthesised in solvothermal batch reactor using zinc acetate as precursor and ethanol as solvent, without any surfactant addition. Commercial batch Teflon reactor of 21 mL was used and filled 80 % capacity with 0.1 M zinc acetate solution. The reactor was heated in an oven and held at a constant temperature for 12 h. In order to investigate the temperature effect on the characteristics of the generated particles, the reactor temperatures were varied at 120, 140, 160, and 180 °C. The powder was characterised by its morphology, crystallinity, and photoluminescence spectra via scanning electron microscopy (FE-SEM, Hitachi), x-ray diffraction (XRD, Phillips), and photoluminescence spectrometer (Simadzu) respectively. Spherical nanoparticles were generated for particles synthesised without LiOH addition into precursor. By adding 0.14 M LiOH into the precursor, rod particles were obtained with an aspect where the ratio (length to diameter) of particle increased with temperatures. Based on the X-ray diffraction analysis, wurtzite structure of ZnO in a hexagonal phase was formed. Neither impurities nor other crystalline phases were observed in the samples. The crystalline size increased from 19 to 28 nm by increasing the reactor temperature from 120 to 180 °C. LiOH addition led to decrease in the crystalline size at the same reactor temperature. Their crystalline size increased from 16 to 23 nm by increasing the reactor temperature from 120 to 180 °C. Photoluminescence intensity increased with temperatures. LiOH addition was able to shift the photoluminescence emission spectra peak from wavelength of 421 nm to 457 nm by excitation at wavelength of 250 nm. It corresponded to the dominant emission shifted from violet to blue by adding LiOH during the synthesis.

High burnup calculation characteristics of traveling wave reactor

The traveling wave reactor (TWR) is an innovative nuclear system, whose discharge burnup is 400 GWd/tHM, about three to four times of existing fast reactor and six to eight times of pressurized water reactor. High discharge burnup forces the present codes to face the great challenges in precision.This paper studies the high burnup calculation characteristics of traveling wave reactor from energy spectrum, importance of fission production and calculation error accumulation of fuel consumption by KYLIN-1 code. The analysis results of typical traveling wave reactor hexagonal assembly show that the low enriched uranium assemblies have different energy spectra at beginning and end of life, which cause big calculation error ofkinf by existing code system. To ensure the correctness of the traveling wave reactor burnup calculations, the burn chain should contain 70 kinds of important fission product nuclides. The calculation error accumulation of fuel consumption is small when the burnup step is increased. The calculation error ofkinf is about 0.001% each burnup step.

Influence of Two Types of Connections in Driver-Retention Screw Assembly.

Rehabilitation with implant-supported prostheses has reached high success rates. However, mechanical failures are still reported, mainly in retention screws of abutments in single implant-supported crowns; which is designed to be the weakest structure and the first component to fail under overloading. In this sense, the aim of this in vitro study was to evaluate the influence of different joint designs (square or hexagonal) on resistance to deformation of driver-retention screw assembly of 3 commercial brands (Neodent, Singular, and Sin). A total of 42 retention screws from 3 commercial brands were used. The samples were divided into 2 joint groups, square (SQU) and hexagonal (HEX), and separated by commercial brands. Several components (implants and abutments) with standard platform (4.1 mm in diameter) were used. The resistance to deformation of the driver-retention screw assembly was measured using an accurate digital torque wrench for all commercial brands (Neodent [NEO], Singular [SGL], and Sin [SIN]) and joint designs (square or hexagonal). It was found no statistically significant difference (P <0.05) among the brands evaluated. On the other hand, square screws showed higher resistance to torsion than hexagonal screws; regardless the commercial brand.

Nel hydrogen project JV with PowerCell, Hexagon Composites

Nel hydrogen project JV with PowerCell, Hexagon Composites

Comparative study of 27G vs 25G vitrectomy for idiopathic epiretinal membrane

Objective To evaluate the effect of 27G pars plana vitrectomy (PPV) and 25G PPV on idiopathic epiretinal membrane (IMEM). Methods Thirty-eight eyes of 38 patients with IMEM were enrolled into this retrospective and comparative study. Eighteen eyes were treated with 27G PPV (group A), 20 eyes underwent 25G PPV (group B) voluntarily. The best corrected visual acuity (BCVA), intraocular pressure (IOP), slit-lamp microscope, indirect ophthalmoscopy, fundus color photograph, ocular coherence tomography (OCT) and counting of corneal endothelial cells (CEC) were examined before the surgery. BCVA results were converted to the logarithm of the minimum angle of resolution (logMAR) visual acuity. There was no statistically significant difference between two groups in terms of BCVA, IOP, foveal macular thickness (FMT), the counting of CEC and CEC hexagon rate before the surgery (t=1.627, 0.860, 0.293, 1.238, 0.697; P>0.05). All operations were performed by the same doctor. Operation time for vitrectomy and peeling membrane was recorded. BCVA, IOP, OCT, FMT, counting of CEC and the improvement of metamorphopsia were observed on 1, 7 days and 1, 3 months after PPV. Results The mean operation time for vitrectomy in group A and B were (6.7±2.8), (10.5±3.3) min, respectively. The mean operation time for vitrectomy in group A was significantly longer than that in group B (t=3.084, P<0.05). The mean operation time for peeling membrane in group A and B were (10.2±5.2), (11.0±5.9) min, respectively. There was no statistically significant difference between two groups in terms of the time for peeling membrane (t=1.970, P=0.187). On 1, 7 days and 1, 3 months after PPV, the difference of BCVA (t=1.463, 0.683, 0.961, 1.226; P=0.833, 0.509, 0.699, 0.744) and IOP (t=1.314, 1.262, 0.699, 1.116; P=0.763, 0.721, 0.534, 0.712) between two groups were not statistically significant. On 1 day after PPV, there were 2 eyes and 5 eyes with <9 mmHg (1 mmHg=0.133 kPa) IOP in group A and B. On 7 days and 1, 3 months after PPV, the difference of FMT between two groups were not statistically significant (t=1.257, 1.368, 1.437; P=0.735, 0.745, 0.869). On 3 months after PPV, the difference of CEC between two groups were statistically significant (t=2.276, P<0.05); the difference of hexagon rate between two groups were not statistically significant (t=1.473, P=0.889). Conclusion The efficacy of 27G PPV for IMEM appears similar to 25G PPV. But 27G PPV has a shorter operating time for vitrectomy, a more stable IOP and a minimal damage to CEC. Key words: Vitrectomy; Surgical procedures, minimally invasive; Macula lutea; Membranes; Comparative effectiveness research

Axial compressive behavior of special-shaped concrete filled tube mega column coupled with multiple cavities

The compressive behavior of special-shaped concrete filled tube (CFT) mega column coupled with multiple cavitiesis studied by testing six columns subjected to cyclically uniaxial compressive load. The six columns include three pentagonal specimens and three hexagonal specimens. The influence of cavity construction, arrangement of reinforcement, concrete strength on failure feature, bearing capacity, stiffness, and residual deformation is examined. Experimental results show that cavity construction and reinforcements make it possible to form a combined confinement effect to in-filled concrete, and the two groups of special-shaped CFT columns show good elastic-plastic compressive behavior. As there is no axial bearing capacity calculation method currently available in any Code of practice for special-shaped CFT columns, values predicted by normal CFT column formulas in GB50936, CECS254, ACI-318, EC4, AISCI-LRFD, CECS159, and AIJ are compared with tested values. The calculated values are lower than the tested values for most columns, thus the predicted bearing capacity is safe. A reasonable calculation method by dividing concrete into active and inactive confined regions is proposed. And high accuracy shows in estimating special-shaped CFT columns either coupled with multiple cavities or not. In addition, a finite element method (FEM) analysis is conducted and the simulated results match the test well.

The Analysis of Vocational Behavior in the Inconsistency Profiles using Holland's Hexagonal Model

The Analysis of Vocational Behavior in the Inconsistency Profiles using Holland's Hexagonal Model

The Analysis Study on Correlation between the Axis of Investigative · Enterprising(IE) in Holland Hexagonal Model and Job Value

The Analysis Study on Correlation between the Axis of Investigative · Enterprising(IE) in Holland Hexagonal Model and Job Value

Development and Characterization of Gear Shape Porous Scaffolds Using 3D Printing Technology

Continuous porous structures of biodegradable polylactic acid (PLA) were fabricated using a rapid prototyping machine with the three dimensional fused deposition modeling (FDM) technique. Effects of two different circle packing methods, the square (SQ) and the hexagonal (HEX) packings, and different pore diameters on the compressive mechanical properties were examined. The compression test results showed that SQ1 and HEX1 with 1 mm pore diameter had the largest compressive properties, suggesting that the microstructures were well constructed compared to the other specimens. Although SQ0.7 and HEX0.7 exhibited the lowest porosities, the modulus values were lowest, indicating that the microvoids degraded the stiffness of the structures. Scanning electron microscopy of the damaged regions suggested that microcracks were generated along the interlayers or within the layers due to bending deformation and the final fracture were initiated with these microcracking mechanism. It is thus concluded that the fabrication process must be improved so that the microcrack formation is minimized. Finite element analysis was used as an evaluation tools by comparing the experimental compressive modulus and a good agreement was exhibited correspondingly.

Between Rome and the Sea: Ancient and Recent Gateways to the Eternal City

While traveling through the flat expanse stretching over its southwestern area, it is possible to see the unusual image of Rome as a city that overlooks the sea. In this area, rich of landfalls, many buildings act as gateways, some of which of international relevance, such as the “Leonardo da Vinci” intercontinental airport. Others accesses are only imagined by architects, from Karl Friedrich Schinkel’s Laurentinum – his reconstruction of Plinius’s Villa – to Adalberto Libera’s projects both for the seafront of Castel Fusano and for the Gateway to Sea. Over all, the ancient seaport of Rome is a potential engine of development and at the same time a symbol of historical memory. A perfect geometrical shape, the hexagonal port’s basin seems to imitate the planimetric shape of Rome’s historical centre that, through a translation of meaning, is cast toward the sea, in a sense prefiguring its destiny.

A Sensitivity Analysis of the Dynamic Behavior of Aluminium Honeycomb Sandwich Panels

Paper deals with an investigation of the dynamic behavior of aluminium honeycomb sandwich panels. The presented study is based on numerical modal analysis where the free vibrations of nine panels are analyzed in order to examine the influence of geometric parameters, such as thickness and height of the core, on their modal parameters. The analyzed panels have a rectangular shape and consist of two aluminum alloy face sheets of thickness 1 mm and hexagonal aluminum honeycomb core, of which height and wall thickness are varying. Additionally, the modal parameters of one single core were analyzed in dependence of wall thickness. The all FEM models were built and the simulations were executed in Abaqus/CAE. The results (natural frequencies and mode shapes) are processed in tabular and graphical form.

Giant Gyroid and Templates from High-Molecular-Weight Block Copolymer Self-assembly.

We present a feasible approach to the direct development of three-dimensionally (3D) bicontinuous gyroid (GYR) nanostructure in high-molecular-weight, composition-controlled polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) films. The use of a neutral solvent vapor to elaborately control the swelling of block copolymer (BCP) films is essential to generate a direct pathway to GYR (or giant GYR) structure through a hexagonal (HEX) cylindrical morphology in the same material, because the thermal ordering of highly entangled BCP imposes the limit on the chain mobility. Along with the improved mechanical strength arising from the high molecular weight property of the polymers, the structural integrity and overall excellence of a large-scale GYR morphology were confirmed by the results of membrane performance, which showed greater permeability through the nanoporous GYR structure up to by a factor of three than that through the HEX structure. Moreover, a 3D nanoporous GYR template was applied to an affordable material to reproduce an inverse skeletal replica of the GYR structure with its structure being uniformly interconnected. This simple approach to the GYR template, owing to its structural tunability in a controlled composition of BCP, is anticipated to be applicable to a wide range of materialization for practical systems.

Renormalisation group corrections to neutrino mixing sum rules

Neutrino mixing sum rules are common to a large class of models based on the (discrete) symmetry approach to lepton flavour. In this approach the neutrino mixing matrix $U$ is assumed to have an underlying approximate symmetry form $\tilde{U}_{\nu}$, which is dictated by, or associated with, the employed (discrete) symmetry. In such a setup the cosine of the Dirac CP-violating phase $\delta$ can be related to the three neutrino mixing angles in terms of a sum rule which depends on the symmetry form of $\tilde{U}_{\nu}$. We consider five extensively discussed possible symmetry forms of $\tilde{U}_{\nu}$: i) bimaximal (BM) and ii) tri-bimaximal (TBM) forms, the forms corresponding to iii) golden ratio type A (GRA) mixing, iv) golden ratio type B (GRB) mixing, and v) hexagonal (HG) mixing. For each of these forms we investigate the renormalisation group corrections to the sum rule predictions for $\delta$ in the cases of neutrino Majorana mass term generated by the Weinberg (dimension 5) operator added to i) the Standard Model, and ii) the minimal SUSY extension of the Standard Model.

Enhanced Crystallization Behaviors of Silicon-Doped Sb2Te Films: Optical Evidences.

The optical properties and structural variations of silicon (Si) doped Sb2Te (SST) films as functions of temperature (210–620 K) and Si concentration (0–33%) have been investigated by the means of temperature dependent Raman scattering and spectroscopic ellipsometry experiments. Based upon the changes in Raman phonon modes and dielectric functions, it can be concluded that the temperature ranges for intermediates and transition states are estimated to 150, 120, 90, and 0 K, corresponding to ST, SST25%, SST28%, and SST33% films, respectively. The phenomenon also can be summarized by the thermal evolutions of interband electronic transition energies (En) and partial spectral weight integral (I). The disappearance of intermediate (INT) state for SST33% film between amorphous (AM) and hexagonal (HEX) phases can be attributed to the acceleratory crystallization of HEX phase by Si introduction. It illustrates that the risk of phase separation (Sb and Te) during the cyclic phase-change processes decreases with the increasing Si concentration. The enhanced crystallization behaviors can optimize the data retention ability and the long term stability of ST by Si doping, which are important indicators for phase change materials. The performance improvement has been analyzed qualitatively from the optical perspective.

Application of staining technology on anterior capsule of lens in white cataract

Objective To evaluate the clinical effect by using a quick and direct staining technology in anterior lens capsule in white cataract. Methods In this randomized prospective study, phacoemulsification was performed in 67 eyes of 52 cases with white cataract. The eyes were divided into two groups randomly: Group A and Group B. The anterior capsule of the lens was stained with 0.06% trypan blue before creating continous curvilinear capsulorhexis (CCC) in Group A in 34 eyes, and 0.06% trypan blue with sterilized air was used in Group B in 33 eyes. The following parameters were compared between the two groups, including the success rate of CCC, endothelial cell density, ultrasound energy, effective phacoemulsification time and surgical complications. Results After staining, the anterior capsule presented light blue colour and was easy to be distinguished. In the 67 eyes with white cataract, success rate of CCC was 100%. There was no significant difference in the density of corneal endothelia cell, average ultrasound energy, effective phacoemulsification time or surgical complication between two groups after surgery (P>0.05). There was a lower loss rate of corneal endothelial cell density in Group A (7%±1.1%) than that of Group B (10%±1.2%). The percentage of hexagonal cells in Group A (48.6%±13.5%) was higher than that of Group B (44.0%±9.5%). There was no statistically significant difference between two groups in loss rate of corneal endothelial cell (t=-0.691, P=0.492) and percentage of hexagonal cell (t=-1.509, P=0.137). Conclusion Injection of 0.06% trypan blue into the anterior chamber to stain the anterior lens capsule is safe and effective in white cataract. Key words: Cataract, white; Continuous curvilinear capsulorhexis; Staining, anterior capsule, lens; Trypan-blue

Formation of cell sheet on acellular porcine corneal stroma with human corneal endothelial cells cocultured by mouse embryonic stem cell conditioned medium

Background Corneal transplantation faces a great challenge because of the shortage of corneal donors and difficulty of human corneal endothelial cells (HCECs) regeneration in vitro.So the study on tissue engineering cornea is still a main topic.Previous research showed that mouse embryonic stem cell conditioned medium (ESC-CM) improved the proliferative capacity of HCECs in vitro, and acellular porcine corneal stroma (APCS) was a good saffold material.However, whether HECEs cultured by mouse ESC-CM can form cell sheet in vitro were rarely studied. Objective This study was to investigate the potential that HCECs cultured by mouse ESC-CM form a monolayer cell sheet. Methods The supernatant of ESC-CM was collected after mouse ES-E14 cells were cultured, and the cultured medium was centrifuged and mixed with 75% human corneal endothelium medium (CEM) at a proportion of 1∶3 to prepare the 25% ESC-CM system.Primary cultures of HCECs were established from explants of corneal limbal with Descemet's membrane, and the cells were identified by using reverse-transcription PCR to determine the expressions of collagen Ⅷ (Col Ⅷ) mRNA and neuron-specific enolase (NSE) mRNA in the cells.APCS was prepared by decellularization with phospholipase A2 and bicarbonate solution, and the second generation of HCECs were inoculated on the sterilized APCS at a 800/mm2 density.The morphology of the cells was observed by hematoxylin-eosin staining under the phase-contrast microscope.The expressions of zona occludens protein-1 (ZO-1) and Na+ -K+ -ATPase in the cell sheet were detected by immunofluorescence staining. Results The second generation of HCECs cultured with 25% ESC-CM in vitro showed the hexagon in shape with positive expressions for Col Ⅷ mRNA and NSE mRNA.Decellularization APCS was transparent, and no corneal cells were seen, the structures of corneal collagenous fibres were regular.HCECs attached closely to APCS and formed monolayer sheet 7 days after culture on the APCS with the cell density of (2 694±143)/mm2.ZO-1 and Na+ -K+ -ATPase were positively expressed on the HCECs sheet. Conclusions Twenty-five percent ESC-CM promotes the proliferation and maintains the normal morphology of HCECs.APCS provide a good scoffold and microenvironment for the formation of HCEC sheet.The HCEC sheet Possesses the pump function of HCECs and is a good corneal donor for transplantation. Key words: Corneal stroma/transplantation; Endothelial cells, corneal/cytology; Humans; Tissue engineering/methods; Tissue scaffolds; Culture media, conditioned; Embryonic stem cells, mouse; Acellular corneal stroma, porcine

(1 + n) sequential dissection of a rectangle into m-GONS, m ∈{3,5,6,7,8}

This paper gives algorithms to dissect a rectangle sequentially into polygons that can be reassembled to a rectangle, which is similar to the initial rectangle, and [Formula: see text]-similar equilateral triangles or regular hexagons and also pentagons or heptagons or octagons with symmetry.

Arranging kings k-dependently on hexagonal chessboards

Arranging kings k-dependently on hexagonal chessboards

Improved Computational Model of Grid Cells Based on Column Structure

To simulate the firing pattern of biological grid cells, this paper presents an improved computational model of grid cells based on column structure. In this model, the displacement along different directions is processed by modulus operation, and the obtained remainder is associated with firing rate of grid cell. Compared with the original model, the improved parts include that: the base of modulus operation is changed, and the firing rate in firing field is encoded by Gaussian-like function. Simulation validates that the firing pattern generated by the improved computational model is more consistent with biological characteristic than original model. Besides, the firing pattern is badly influenced by the cumulative positioning error, but the computational model can also generate the regularly hexagonal firing pattern when the real-time positioning results are modified.

Rapid differentiation of human ESCs into RPE cells by defined xeno-free culture system

Background Subretinal transplantation of retinal pigment epithelium (RPE) cells for the treatment of age-related macular degeneration (AMD) have accelerated the drive to develop xeno-free cultivation system that support the rapid differentiation of human embryonic stem cells (hESCs) into ES-RPE cells. Objective This study was to report a modified xeno-free culture system and method for accelerating derivation of hESCs to differentiate into RPE cells. Methods This study was approved by Ethic Committee of Zhongshan Ophthalmic Center.HESC H1 line was cloned and cultured in Vitronectin XF™-coated 6-well dish with xenogenetic-free medium.Cells were cultured in 50 ng/ml noggin, 10 ng/ml DKK-1 and 10 ng/ml insulin like growth factor-1 (IGF-1) medium for 2 days, and then the concentration of noggin was decreased to 10 ng/ml and 5 ng/ml basic fibroblast growth factor (bFGF) and cultured for the following 2 days.Sequentially, noggin and bFGF were removed and cultured for 2 days.Finally, 1 μmol/L CHIR99021 was added in medium for 6 days.Morphological changes in the progress of ESCs differentiation into RPE were observed by Living Cell Imaging System.The expression of Mitf and RPE65, RPE cells-specific markers, in the cells were detected by immunofluorescence technique, and the relative expression levels of RPE cells-specific marker mRNA were assayed using real time fluorescent quantitation PCR. Results Polygonal-shape monolayer cells which contained pigments were initially observed at day 14 after cultured with the cobblestone- like arrangement.Mitf and RPE65 were strongly expressed in the hES-derived RPE cells 35 days after induced, showing red fluorescence, and the cells presented hexagonal shape at cultured day 60 with numerous pigment granules in cytoplasm.Compared with before differentiation, the expression levels of Mitf mRNA in hES-RPE cells increased by (3.43±2.77) folds and (8.91±2.83) folds, and the expression levels of RPE65 mRNA increased by (14.60±3.94) folds and (87.16±9.32) folds at day 7 and day 14 after differentiation, respectively (all at P<0.05). Conclusions A defined xeno-free culture system is successfully established by adding niacinamide, DKK-1, noggin, IGF-1 and CHIR99021 in xeno-free medium, and this system can accelerate the derivation and differentiation of hESCs into RPE-like cells. Key words: Embryonic stem cells/drug effect; Cell culture techniques/methods; Cell differentiation; Retinal pigment epithelium; Culture media/drug effects; Cell line; Humans; Xeno-free