Amorphous Arrays Research Articles

Bio-inspired robust non-iridescent structural color with self-adhesive amorphous colloidal particle arrays.

Here we propose a new method for constructing highly color fast non-iridescent structural color materials by assembling self-adhesive poly-dopamine coated SiO2 nanoparticles (PDA@SiO2) for amorphous colloidal arrays through a "spraying" process. Simply by alkaline vapor treatment, the adhesive forces and fastness of the amorphous colloidal arrays were significantly improved. This was demonstrated by lap shear tests of tape tearing and cohesive failure as well as a series of fastness tests like sandpaper abrasion, finger wiping and ultrasonic cleaning. Besides, the strengthening fastness reaction could occur on different substrates, including glass, metals, polymers and paper, regardless of their chemical and physical properties. Moreover, the structural color of the PDA@SiO2 arrays was bright due to the broadband absorption of PDA, and was tunable according to the size, PDA content and arrangement of the PDA@SiO2 arrays.

A platinum oxide decorated amorphous cobalt oxide hydroxide nanosheet array towards alkaline hydrogen evolution

A platinum oxide decorated amorphous cobalt oxide hydroxide nanosheet array has been prepared and used for alkaline hydrogen evolution.

Dosimetric Comparison of Amorphous Silicon EPID and 2D Array Detector for Pre-Treatment Verification of Intensity Modulated Radiation Therapy

Purpose: To study the dosimetric characteristics of amorphous silicon Electronic Portal Imaging Device EPID and 2D array detector for dose verification of radiotherapy treatment plans, and the quality assurance QA testing of IMRT was investigated. Materials and methods: All measurements were done with Varian IX linear accelerator, aSi-1000 EPID and 2D array detector. The dose linearity, reproducibility, output factors, dose rate, SDD and response with slap phantom thickness have been measured and compared against those measured by ion chamber. Results: The characteristics of EPID and 2D array: the response of EPID agreed with 2D array and ion chamber 0.6cc. EPID and 2D array showed short-term output reproducibility with SD = 0.1%. The dose rates of 2D array SD = ±0.7%, EPID = ±0.4% compared with a 0.6 cc SD = ±0.5%. Output factor measurements for the central chamber of the EPID and 2D array showed no considerable deviation from ion chamber measurements. Measurement of beam profiles with the EPID and 2D array matched very well with the ion chamber measurements in the water phantom. The EPID is more sensitive to lower energy photons by increasing solid water phantom thickness. The mean and standard deviation passing rates (γ%≤1) for film, 2D array and EPID for 30 IMRT fields of five patients were 95.93 ± 0.96%, 99.05 ± 0.24%, and 99.37 ± 0.12%, respectively. Conclusion: The study shows that EPID and 2D array are a reliable and accurate dosimeter and a useful tool for quality assurance. We found that the EPID was more accurate compared with both 2D array and ion chamber. The gamma criterion of 3%/3 mm is the most suitable criteria for IMRT plans of QA.

In-Situ Synthesis and Characterization of Carbon Dots and TiO2 Nanocomposites Anchored on TiO2 Nanotube Arrays

A modified anodic oxidation method was used to prepare amorphous titanium dioxide nanotube arrays (TiO2NTs) on Ti foil firstly. Then TiO2NTs were decorated with nanocomposites of CDs-TiO2 through designed one-step solvothermal techniques in-situ, accompanying with crystallization of TiO2NTs. The crystallinity of TiO2, morphologies and ingredients of the hybrid nanocomposites could be controlled by solvothermal conditions. It was found solvothermal procedure could play a similar role on the TiO2 crystal formation like the common anneal treatments. Furthermore, there were more Ti-C bonds found in the composites derived from amorphous TiO2NTs undergone a solvothermal process. The measurements of photo-degradation on both methyl blue and rhodamine B showed an excellent photocatalytic activity for CDs-TiO2 decorated TiO2NTs (CDs-TiO2-TiO2NTs) under no matter ultraviolet or visible light irradiation.

Mechanism of Ultra-Fast Actin-Myosin Sliding Producing Cytoplasmic Streaming in Giant Algal Cell, Studied Using the Centrifuge Microscope

In giant intermodal cells of green algae Chara collaria, cytoplasmic streaming is produced by ATP-dependent sliding between myosin heads extending from amorphous cytoplasmic organelles and actin filament arrays (actin cables) fixed on chloroplast rows. The velocity of cytoplasmic streaming is many times faster than the maximum myofilament sliding in skeletal muscle. In this article, we compared steady-state force-velocity (P-V) relations between cytoplasmic myosin and skeletal and cardiac muscle myosins using the centrifuge microscope, in which myosincoated latex beads were made to slide along the actin cables under various centrifugal forces. In contrast with the hyperbolic P-V relation of actin-myosin sliding in skeletal and cardiac myosins, the P-V relation of cytoplasmic myosin versus actin cable sliding was a straight line, indicating a very large duty ratio and a very small rate of chemomechanical energy conversion. Possible mechanisms of the ultra-fast actin-myosin sliding are discussed.Highlights• The velocity of cytoplasmic streaming, caused by ATP-dependent sliding between cytoplasmic myosin and actin cables in giant algal cells is many times faster than ATP-dependent actin-myosin sliding in skeletal and cardiac muscles.• The mechanism of ultra-fast actin-myosin sliding was studied using the centrifuge microscope, in which beads coated with cytoplasmic myosin were made to slide along actin cables under various centrifugal forces serving as loads against cytoplasmic myosin versus actin cable sliding.• Unlike the hyperbolic force-velocity (P-V) relation of skeletal and cardiac muscle actin-myosin sliding, the P-V relation of cytoplasmic actin myosin sliding was a straight line irrespective of the force generated by cytoplasmic myosin.• These results indicate a very large duty ratio and a very small efficiency of chemo-mechanical energy conversion in cytoplasmic actin-myosin sliding.

UV and blue-light anti-reflective structurally colored contact lenses based on a copolymer hydrogel with amorphous array nanostructures

Novel anti-reflective structurally colored contact lenses not only block UV- and blue-light but also avoid the risk of chemical dyes.

Synthesis of Self-Supported Amorphous CoMoO4 Nanowire Array for Highly Efficient Hydrogen Evolution Reaction

Water electrolysis is known as the most environmental friendly and renewable technology to generate hydrogen. To make it more energy-efficient, development of a promising cathodic hydrogen evolution reaction electrocatalyst is important. In this communication, amorphous CoMoO4 nanowire array on Ti mesh (CoMoO4 NWA/Ti) was synthesized via a simple two-step hydrothermal method. As a three-dimensional hydrogen-evolving electrode, CoMoO4 NWA/Ti shows superior catalytic activity in 1.0 M KOH and demands overpotentials of only 81 and 243 mV to achieve current densities of 10 and 100 mA cm–2, respectively. Remarkably, it also has long-term electrochemical durability.

Growth of coiled amorphous carbon nanotube array forest and its electromagnetic wave absorbing properties

Abstract Coiled amorphous carbon nanotube (CACNT) array was prepared by chemical vapor deposition method. The experimental results indicated that the length of as-prepared CACNT array was about 30 μm. The electromagnetic wave absorbing properties were studied through comparison among CACNTs, CACNT-La(NO 3 ) 3 , CACNT-(Fe, Co, Ni) and CACNT-reduced graphene oxide (RGO). The experimental results showed the maximum frequency bandwidth of CACNT-(Fe, Co, Ni) was 6.4 GHz below −5 dB and 2.3 GHz below −10 dB separately. Compared to the pure CACNTs, all the frequency bandwidth had been broaden after adding the modified agent. Meanwhile, the additive of rare earth ions La 3+ could effectively increase the maximum absorption peak (−17.94 dB at 8.96 GHz).

Structurally colored films with superhydrophobicity and wide viewing angles based on bumpy melanin-like particles

Abstract Non-iridescent structural colors and lotus effect universally existing in the nature provide a great inspiration for artificially developing angle-independent and high hydrophobic structurally colored films. To this end, a facile strategy is put forward for achieving superhydrophobic structurally colored films with wide viewing angles and high visibility based on bumpy melanin-like polydopamine-coated polystyrene particles. Here, hierarchical and amorphous structures are assembled in a self-driven manner due to particles’ protrusive surfaces. The superhydrophobicity of the structurally colored films, with water contact angle up to 151°, is realized by combining the hierarchical surface roughness with a dip-coating process of polydimethylsiloxane-hexane solution, while angle-independence revealed in the films is ascribed to amorphous arrays. In addition, benefited from an essential light-absorbing property and high refractive index of polydopamine, the visibility of as-prepared colored films is fundamentally enhanced. Moreover, the mechanical robustness of the films is considerably boosted by inletting 3-aminopropyltriethoxysilane. This fabrication strategy might provide an opportunity for promoting the open-air application of structurally colored coatings.

Electrochemical Characterization of TiO2 Nanotubular Films Exposed in an Aqueous Solution with a pH = 3.2

ABSTRACTTiO2 nanotubular structures were fabricated on Ti polished and unpolished foils exposed to H2O-Glycerol (50-50Vol.%)+0.27 M NH4F at 20V. The obtained TiO2 nanostructures were analyzed by SEM obtaining the morphological characterization, from which the roughness factors were calculated. Crystalline phases of both TiO2 nanotubular films were obtained by XRD after annealing at 450 °C and 600 °C for 2 h. The electrochemical stability of the TiO2 nanotubular films was obtained from the potentiodynamic polarization curves (PC) and the linear polarization resistance (Lpr) techniques, exposing the samples in 1M Na2SO4 + H2SO4 solution (pH = 3.2), such pH is in accordance with the acidic wastewater containing sulfur compounds coming from the industries or acid waters of the aquifers, which have been contaminated from the volcanoes nearby. It was concluded that the electrochemical stability of the crystallized nanotubular films is improved with the increase of the annealing temperature of the amorphous TiO2 arrays, which is associated to the higher composition of anatase and rutile, observing that the major amount of rutile improved the corrosion performance. The photoelectrochemical measurements were carried out in 0.5 M Na2SO4 solution using an 8 W UV lamp at a λ= 365 nm, whose results were recorded at zero bias during 10 min under darkness and illumination intervals of 1 min each. The obtained results were in agreement with the necessary features for being used in photocatalytic water remediation.

Self-Templating Construction of Hollow Amorphous CoMoS4 Nanotube Array towards Efficient Hydrogen Evolution Electrocatalysis at Neutral pH.

Environmentally friendly electrochemical hydrogen production needs the development of earth-abundant catalyst materials for the hydrogen evolution reaction with high activity and durability at neutral pH. In this work, the self-templating construction of a hollow amorphous CoMoS4 nanotube array on carbon cloth (CoMoS4 NTA/CC) is reported, using hydrothermal treatment of a Co(OH)F nanowire array on CC in (NH4 )2 MoS4 solution. When used as a 3D electrode for hydrogen evolution electrocatalysis, the resulting CoMoS4 NTA/CC demonstrates superior catalytic activity and strong long-term electrochemical durability in 1.0 M phosphate buffer solution (pH=7). It shows small onset overpotential of 21 mV and requires low overpotentials of 104 and 179 mV to drive geometrical current densities of 10 and 50 mA cm-2 , respectively. Density functional theory calculations suggest that CoMoS4 has a more favorable hydrogen adsorption free energy than Co(OH)F.

Novel ZnO-TiO2 nanocomposite arrays on Ti fabric for enhanced photocatalytic application

In this study, ZnO-TiO2 nanocomposite arrays on Ti fabric were synthesized via a hydrothermal process, where the amorphous TiO2 nanotube array was used as a precursor. The fabrication process involved the preparation of zinc acetate particles that were modified on TiO2 nanotube arrays. These transformed the amorphous TiO2 to crystallized ZnO-TiO2. The prepared samples were then characterized by X-ray diffractometer, field-emission scanning electron microscope, transmission electron microscope, energy-dispersive X-ray spectroscopy, and photoluminescence. Photodegradation test of methyl orange was examined using the ZnO-TiO2 nanocomposite arrays on the Ti fabric. Following 60 min of UV irradiation nearly 100% photodegradation of the 20 mg L−1 methyl orange solution at pH = 10 was achieved. The degradation products were identified and the photocatalysis process was studied. The results obtained in the study will enable researchers to design a scalable, practical process for dye wastewater treatment.

Unveiling the controversial mechanism of reversible Na storage in TiO2 nanotube arrays: Amorphous versus anatase TiO2

Due to their inherent safety, low cost, and structural stability, TiO2 nanostructures represent a suitable choice as anode materials in sodium-ion batteries. In the recent years, various hypotheses have been proposed regarding the actual mechanism of the reversible insertion of sodium ions in the TiO2 structure, and previous reports are often controversial in this respect. Interestingly, when tested as binder- and conducting additive-free electrodes in laboratory-scale sodium cells, amorphous and crystalline (anatase) TiO2 nanotubular arrays obtained by simple anodic oxidation exhibit peculiar and intrinsically different electrochemical responses. In particular, after the initial electrochemical activation, anatase TiO2 shows excellent rate capability and very stable long-term cycling performance with larger specific capacities, and thus a clearly superior response compared with the amorphous counterpart. To obtain deeper insight, the present materials are thoroughly characterized by scanning electron microscopy and ex situ X-ray diffraction, and the insertion of sodium ions in the TiO2 bulk phases is systematically modeled by density functional theory calculations. The present results may contribute to the development of more systematic screening approaches to identify suitable active materials for highly efficient sodium-based energy storage systems.

Bio-Inspired Bright Structurally Colored Colloidal Amorphous Array Enhanced by Controlling Thickness and Black Background.

Inspired by Steller's jay, which displays angle-independent structural colors, angle-independent structurally colored materials are created, which are composed of amorphous arrays of submicrometer-sized fine spherical silica colloidal particles. When the colloidal amorphous arrays are thick, they do not appear colorful but almost white. However, the saturation of the structural color can be increased by (i) appropriately controlling the thickness of the array and (ii) placing the black background substrate. This is similar in the case of the blue feather of Steller's jay. Based on the knowledge gained through the biomimicry of structural colored materials, colloidal amorphous arrays on the surface of a black particle as the core particle are also prepared as colorful photonic pigments. Moreover, a structural color on-off system is successfully built by controlling the background brightness of the colloidal amorphous arrays.

Assessing the forming temperature role on amorphous and polycrystalline HfO2-based 4 kbit RRAM arrays performance

The impact of temperature during the forming operation on the electrical cells performance and the post-programming stability were evaluated in amorphous and polycrystalline HfO2-based arrays. Forming (between −40 and 150°C), reset and set (at room temperature) operations were applied using the incremental step pulse with verify algorithm (ISPVA). The improvements achieved on the forming operation in terms of time and voltages reduction do not impact the subsequent reset/set results. ISPVA perturbations in LRS/HRS current distributions are almost negligible after the first reset/set operation. In this study the best improvement in forming operation in terms of yield, voltage values and cell-to-cell variability is achieved in polycrystalline samples at 80°C.

Study on morphology evolution of anodic tantalum oxide films in different using stages of H2SO4/HF electrolyte

Three structures: free-standing Ta2O5 nanotube membranes, adhered Ta2O5 nanotube arrays and spark discharge Ta2O5 films, have been fabricated respectively by anodizing pure Ta for one hour in three different using stages of the same original concentration electrolyte consisting of 96 vol% H2SO4 (95–98%) and 4vol% HF (48%) in this work. Stage I: In the 0–10hours used electrolyte, patchy free-standing Ta2O5 nanotube membranes formed within the potential range of 10V–70V; Stage II: In the 30–50hours used solution, highly ordered amorphous adhered Ta2O5 nanotube arrays with top diameter of 40nm–270nm and length of 5μm–122μm were fabricated during 10V–170V; Stage III: When the using time of electrolyte exceeded 50hours, spark discharge films with Ta2O5 crystal phase formed at 180V–200V, and nanotube structure still remained partially in the spark discharge films. The diameter of Ta2O5 nanotubes increases with the increasing of voltage. In addition to Ta and O elements, adhered Ta2O5 nanotube array films contain a small amount of S and F elements, but the spark discharge Ta2O5 films do not consist of S element. Adhered Ta2O5 nanotube arrays and spark discharge Ta2O5 films show excellent hydrophilicity. The current density-time curves of adhered Ta2O5 nanotube arrays obtained at high voltage (70V–170V) exhibit unique fluctuation phenomena and the current oscillation behaviors have a significant influence on the morphologies of nanotube array. Moreover, irritating gases emission on anode and light yellow sediment on cathode occur in the anodization process of Ta2O5 nanotube arrays. This work obtains Ta2O5 nanotube arrays with various structure parameters and expands anodic Ta2O5 film fabrication windows using HF/H2SO4 electrolyte at different stages, meanwhile provides the detailed analyses for growth mechanism of Ta2O5 nanotube arrays. Our results are expected to provide references for the nanostructure preparation on the surface of other metals and alloys by anodization.

Investigation on the role of cost effective cathode materials for fabrication of efficient DSSCs with TiNT/TiO2 nanocomposite photoanodes

Free-standing, micrometer long TiO2 nanotube arrays (TiNTs) were synthesized via anodization by utilizing selected transition metals and non-transition elements as cathode materials. Free-standing TiNTs arrays with the maximum tube length up to 153µm was fabricated with Ti cathode material, whereas, the cost effective cathodes materials of charcoal and graphite pencil yielded nearly 100µm long nanotubes for an anodization time of 48h. The barrier layer was removed from the bottom of the free-standing TiNT arrays using chemical etching process. The as-synthesized open ended free-standing amorphous arrays were then crystallized into anatase phase. The annealed free-standing TiNT array was powdered and mixed with TiO2 nanoparticles (NP) to form TiNT/TiO2 NP composite and then utilized as photoanodes to fabricate dye sensitized solar cells (DSSCs). The J-V characteristics and the performances of the solar cells were studied and compared. The results indicate that the TiNT arrays developed with different cathode materials are similar to or in some cases superior to those nanotubes obtained using Pt cathode. Thus, the strategy employed in this work provides a simple, efficient and economical fabrication method for large scale production of TiNT arrays.

Structural color coating films composed of an amorphous array of colloidal particles via electrophoretic deposition

It is desirable to fabricate colorful coatings that have nonfading properties and are environmentally friendly. In this study, a novel approach for creating structural color coatings from monodisperse silica particles is presented. The structural color coating films, formed from an array of silica particles with a small amount of black additive, are easily prepared by a simple electrophoretic deposition (EPD) technique. The arrangement of the particle array is controlled by varying the applied voltage and deposition time. The iridescence, that is, the angular dependence, of the structural color dramatically changes with the arrangement of the particle array. A variety of colored coatings can be produced by changing the size of the particles. Structural color coatings on materials with curved surfaces and complicated shapes are also achieved by the EPD method.

Photoluminescence of pure silicon quantum dots embedded in an amorphous silica wire array

Si quantum dots embedded in an amorphous silica wire array were first synthesized using thermal evaporation.

Biomimetic Construction of Non‐Iridescent Structural Color Films with High Hydrophobicity and Good Mechanical Stability Induced by Chaotic Convective Coassembly Method

This article presents an originative strategy to biomimetically construct non‐iridescent structural color films with high hydrophobicity and good mechanical stability. In this strategy, the amorphous array of polystyrene (PS) particles is easily fabricated via a simple chaotic convective flow coassembly method to imitate the amorphous nanostructures of avian feathers. An amorphous array is locked by introducing fluorinated polyacrylate (FPA) latex to the voids between the PS particles as binder, which is similar to the locking effect of an organism of a bird's wing. Meanwhile, the high hydrophobicity (140° contact angle) and good mechanical stability of the films are obtained owing to hydrophobicity of FPA and high roughness of the amorphous array. The as‐prepared films retain their brilliant colors under natural light, and this property is essential for their applications in full‐color displays and responsive materials.