Needle-like Nanostructures Research Articles

Highly sensitive biosensor based on target induced dual signal amplification to electrochemiluminescent nanoneedles of Ru(II) complex

Here, electrochemiluminescent nanoneedles of Ru(II) complex were synthesized to fabricate an “off-on” electrochemiluminescence (ECL) biosensor in assistance with target Pb2+ induced dual signal amplification. Firstly, new needle-like nanostructures of luminous Ru(II) complex (RuNDs) different from the previous ones were prepared through solvent evaporation induced self-assembly on the electrode, which processed high ECL efficiency due to massive Ru(II) complexes in those structures, giving a strong initial ECL signal. To further improve the stability of the RuNDs film, silver nanowires (AgNWs) with excellent electric-conductivity dispersed in Nafion solution were modified by film formation, which was also convenient for subsequent modification. Through Ag-S bond, the DNA duplex formed by ssDNA with -SH (S1) and ssDNA modified with ferrocene (S2-Fc) was immobilized, leading to an obvious decrease of the ECL signal because of the effective quenching effect of Fc (off state). With the presence of target Pb2+, G-quadruplex structure was formed owing to the high specific affinity between S1 and Pb2+, making S2-Fc fall off from the electrode. Interestingly, the ECL signal not only could be recovered due to the abscission of Fc, but also improved by the generation of Pb2+-G-quadruplex (on state). Based on the effective dual signal amplification, a sensitive ECL biosensor was constructed for Pb2+determination with a low estimated detection limit down to 0.33 pM. The strategy using luminous Ru(II) complex as precursor to directly prepare needle-like nanostructure was a convenient and effective way to enhance the ECL efficiency. Meanwhile, the simple and efficient target Pb2+ induced dual signal amplification would provide new thought for signal enhancement in the fabrication of biosensors.

Polylactide Composite Pins Reinforced with Bioresorbable Continuous Glass Fibers Demonstrating Bone-like Apatite Formation and Spiral Delamination Degradation.

The emergence of polylactide composites reinforced with bioresorbable silicate glass fibers has allowed for the long-term success of biodegradable polymers in load-bearing orthopedic applications. However, few studies have reported on the degradation behavior and bioactivity of such biocomposites. The aim of this work was to investigate the degradation behavior and in vitro bioactivity of a novel biocomposite pin composed of bioresorbable continuous glass fibers and poly-L-D-lactide in simulated body fluid for 78 weeks. As the materials degraded, periodic spiral delamination formed microtubes and funnel-shaped structures in the biocomposite pins. It was speculated that the direction of degradation, from both ends towards the middle of the fibers and from the surface through to the bulk of the polymer matrix, could facilitate bone healing. Following immersion in simulated body fluid, a bone-like apatite layer formed on the biocomposite pins which had a similar composition and structure to natural bone. The sheet- and needle-like apatite nanostructure was doped with sodium, magnesium, and carbonate ions, which acted to lower the Ca/P atomic ratio to less than the stoichiometric apatite and presented a calcium-deficient apatite with low crystallinity. These findings demonstrated the bioactivity of the new biocomposite pins in vitro and their excellent potential for load-bearing applications.

Preparation of new semiconducting corrole nanostructures and their application as gas sensor

Herein, the meso-phenyl substituted corrolato copper complex Cu[Cor(Ph)2(p-HOPh)] 1 [Cor(Ph)2(p-HOPh) = 10-(4-hydroxylphenyl)-5,15-diphenylcorrole] is designed and successfully synthesized. Its self-assembly property is comparatively investigated with that of the analogue meso-phenyl substituted corrolato copper complex Cu[Cor(p-CH3OOCPh)3] 2 [Cor(p-CH3OOCPh)3 = 5,10,15-tris(p-carboxymethylphenyl)corrole] by various spectroscopic methods. The H-aggregate nature was revealed in both nanostructures formed from copper corroles 1 and 2 during the self-assembling process. But, in n-hexane copper corrole 1 self-assembled into large scale needle-like nanostructures, while copper corrole 2 self-assembled into ribbon-like bundles with long and flexible fibrils. The devices fabricated from these nanostructures display excellent semiconducting performance, with the electric conductivity as high as 1.8 × 10−4 for 1 and 2.0 × 10-3 S cm-1 for 2, respectively. Meanwhile, this two kinds of nanostructures exhibit highly sensitive n-type response to NO2 gas in the range of 100 ppb to 1 ppm at room temperature. Particularly, their sensor responses are fitting non-linear curves with respect to the NO2 gas concentrations (R2 > 0.99), suggesting the great potential applications of the copper corrolato derivatives in the field of chemical sensors.

An ultrasensitive sensor based on polyoxometalate and zirconium dioxide nanocomposites hybrids material for simultaneous detection of toxic clenbuterol and ractopamine

A new electrochemical sensor based on isopolyacid anions (NH4)5PV8Mo4O40 (NPVMo) and transition metal zirconium dioxide (ZrO2) nanocomposites was prepared in double signal amplification for the simultaneous detection of clenbuterol (CLB) and ractopamine (RAC). This is the first time that ZrO2 was used as POM carrier to prepare electrochemical sensor. Scanning electron microscopic (SEM), nitrogen adsorption/desorption isotherms and X-ray diffraction (XRD) test showed that the synthesized ZrO2 nanoparticles have a needlelike nanostructure and a larger surface area. The electrochemical measurements such as cyclic voltammetry (CV), amperometric and differential pulse voltammetry (DPV) indicated that the NPVMo/ZrO2/GCE exhibited much high stability, fast response, good conductivity and electrocatalytic actives, which enhanced peak current and negatively shifted the oxidation potentials of CLB and RAC. Due to the synergistic action between NPVMo and ZrO2 nanoparticles, DPV results showed that the oxidation of CLB and RAC on NPVMo/ZrO2/GCE could be detected selectively and sensitively with low limits of detection, 5.03 × 10−9 mol L−1 for CLB and 9.3 × 10−7 mol L−1 for RAC, and a wide range for calibration curves of CLB and RAC from 0.1 to 1000 μM and 3.0 to 50 μM, respectively. In addition, the proposed sensor was applied to detect content of CLB and RAC in pork sample, and the recovery was over the range from 94.4 to 102.3%.

Field Electron Emission from the Tip of a Graphite Fiber

Usually carbon wires cannot be used for obtaining remarkable field electron emission because the difficulty of sharpening its tip with a sufficient small radius of curvature to fit the electrical field. However, a large number of small fragments are formed on tips of graphite fibers after a discharge treatment with 10 kV DC high voltage on graphite fibers. These fragments observed by SEM and HRFEM are spheres, flakes and needle-like nanostructures with the size around 50 nm. In this case, each of these spheres and flakes can be an emission center in field emissions and some detectable emission currents can be obtained with a low applied voltage. Experimental results show that a single graphite fiber of 20µm diameter can generate near 0.2 mA emission current with 4 kV applied voltage and the stability have been measured to be less than 10 %. It is expected that graphite fibers as a novel cold cathode material will provide a wide range of applications such as in flat panel displays, high-power and high-brightness vacuum electronic devices, and vacuum microelectronic devices.

Self-assembled gold micro/nanostructure arrays based on superionic conductor RbAg4I5 films

Herein, we propose a new strategy to fabricate gold (Au) micro/nanostructure arrays by photocatalytic solid-state electrochemical reaction between superionic conductor RbAg4I5 and Au films. The Au and RbAg4I5 films were successively deposited on a clean quartz substrate by vacuum thermal deposition method. A copper microgrid possessing periodic holes 100 μm in diameter was put above the RbAg4I5 film as a mask plate, whereupon irradiation from a 405 nm wavelength laser was used to diffuse gold ions (Au+ ions) into vacant silver sites of RbAg4I5 and transfer Au+ through ion passageways in the RbAg4I5 film. When the laser was turned off, the Au+ ions were easily reduced due to low activity compared to the silver (Ag+) ions. After multiple on/off cycles of the 405 nm laser, the irradiated area of uniform Au film exhibited a periodic structural unit array whose period was the same as that of the mask plate hole array. Atomic force microscope and scanning electron microscope images revealed that a self-assembled needle-like nanostructure array grew perpendicular to the substrate surface inside each circle’s structural unit. The height of the grown nanostructure array increased with laser power density. Raman enhancement of the gold nanostructure array as substrate was detected using Rhodamine 6G (R6G) ethanol solutions as probe molecules. The enhancement effect increased with the height of the grown nanostructure array, and could increase by two orders of magnitude greater than that of unirradiated Au film. This strategy offers a new method for the micro/nanostructure processing of gold and provides microscale-array-mediated surface-enhancement Raman-scattering (SERS) substrates comprising Au nanostructures for application in high-sensitivity spectrum analysis.

Self-assembly 3D needle-like nickel nanostructure growth on carbon fibers by regulating prepare conditions and exploited as bifunctional material

Three-dimensional (3D) needle-like nickel carbon nanofibers (Ni/CNFs) were successfully fabricated as bifunctional materials by controlling the conditions in the preparation process. The effects such as different molar ratio, carbonization temperature and carbonization time of nanofibers morphology structures were investigated in the experiments. 3D needle-like Ni/CNFs materials as catalyst were applied in Heck reaction which exhibited a certain catalytic activity. Furthermore, this material was oxidized into the nickel and nickel oxidized (Ni/NiO) carbon nanofibers in the air atmosphere, forming electrode material. The electrochemical tests were carried out in electrolyte of 4 M KOH, and it was demonstrated that Ni/NiO-5 was the best electrode material with a high specific capacitance of 676 F g−1 at the current density of 0.5 A g−1. Cycling performance as an index of evaluation material was also investigated and the capacitance retention kept of 108% after 5000 cycles, which exhibited the excellent stability. Furthermore, the Ni/NiO-5 as the positive electrode and CNFs as negative electrode were assembled into the asymmetric supercapacitor (ASC) in 4 M KOH solution. The resulting Ni/NiO-5//CNFs device represented maximum energy density of 90.9 Wh kg−1 at the power density of 1350 W kg−1. Bifunctional materials could not only be utilized in catalytic field, but also be applied as electrode materials for the supercapacitor. This work offers a novel 3D needle-like structure for improving the potential of metal oxides for energy storage applications and this material also can be used as catalyst in Heck reaction, which displayed widely prospects applications as bifunctional materials.

Rapid and area-specific coating of fluoride-incorporated apatite layers by a laser-assisted biomimetic process for tooth surface functionalization

Surface functionalization of teeth with fluoride-incorporated apatite layers displays great potential in treatments and prevention of dental disorders. In this study, we used a sintered hydroxyapatite (sHA) substrate as a model material of teeth, and established a rapid and area-specific coating technique of fluoride-incorporated apatite layers by using a laser-assisted biomimetic (LAB) process. In this technique, a sHA substrate was irradiated on the surface with a Nd:YAG pulsed UV laser for 30 min in supersaturated calcium phosphate (CaP) solutions with various fluoride concentrations. The fluoride concentration in the CaP solution was varied to control morphology, crystalline structure, and fluoride content of the resulting layers. Without fluoride in the CaP solution, an octacalcium phosphate (OCP) layer with a flake-like structure was formed on the laser-irradiated surface of the substrate. The addition of fluoride (1000 µM and 3000 µM) to the CaP solution led to the formation of fluoride-incorporated apatite layers with an enamel-like needle-like nanostructure. The fluoride-incorporated apatite layers adhered firmly to the sHA surface and reduced acid dissolution of the sHA substrate by acting as a protective covering. Additionally, the layers released fluoride ions for more than 24 h, and exhibited antibacterial activity relative to a caries-causing bacterium, namely Streptococcus mutans. Thus, our LAB process can potentially act as a new tool for functionalization of tooth surfaces. Statement of SignificanceWe used a sintered hydroxyapatite (sHA) substrate as a model material of teeth, and established a rapid and area-specific coating technique of fluoride-incorporated apatite layers on the sHA surface by using our laser-assisted biomimetic (LAB) process. In this process, pulsed laser was utilized to accelerate seeded crystal growth in supersaturated calcium phosphate solutions supplemented with NaF. The thus-fabricated fluoride-incorporated apatite layers consisted of enamel-like needle-like nanocrystals with c-axis orientation. These fluoride-incorporated apatite layers adhered firmly to the sHA surface, reduced acid dissolution of the sHA substrate by acting as a protective covering, and exhibited antibacterial activity against Streptococcus mutans through the fluoride release. Thus, our LAB process can potentially act as a new tool for functionalization of tooth surfaces.

A green and simple hydrothermal approach to synthesize needle-like CuInS2 nanostructures for solar cells

Herein, needle-like nanostructures of CuInS2 (CIS) were prepared through a green, simple and surfactant-free hydrothermal method. In this method, cysteine was employed as a capping agent, sulfide source and reductant for successful reducing Cu2+–Cu+. Moreover, [Cu(en)2]Cl2 complex was synthesized as a new Cu source. Effect of different parameters on particles shape and size was well studied. Finally, as-prepared needle-like CIS nanostructures were utilized in quantum dot-sensitized solar cells (QDSSCs) and their behavior and efficiency were also analyzed. The obtained results emphasize on significant effect of particles shape and size on output efficiency of solar cells and using needle-like nanostructures led to higher efficiency compared to other morphologies. Depositing needle-like nanostructures of CIS on nanoparticles of CIS resulted in ~ 171 and ~ 95% improvements in efficiency compared to bare nanoparticles of CIS and bare needle-like CIS nanostructures, respectively.

Isolation and characterization of nanocrystalline cellulose from roselle-derived microcrystalline cellulose

Roselle fiber is a renewable and sustainable agricultural waste enriched with cellulose polysaccharides. The isolation of Nanocrystalline cellulose (NCC) from roselle-derived microcrystalline cellulose (MCC) is an alternative approach to recover the agricultural roselle plant residue. In the present study, acid hydrolysis with different reaction time was carried out to degrade the roselle-derived MCC to form NCC. The characterizations of isolated NCC were conducted through Fourier Transform Infrared Ray (FTIR), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). As evaluated from the performed morphological investigations, the needle-like shape NCC nanostructures were observed under TEM and AFM microscopy studies, while irregular rod-like shape of NCC was observed under FESEM analysis. With 60min hydrolysis time, XRD analysis demonstrated the highest NCC crystallinity degree with 79.5%. In thermal analysis by TGA and DSC, the shorter hydrolysis time tended to produce NCC with higher thermal stability. Thus, the isolated NCC from roselle-derived MCC has high potential to be used in application of pharmaceutical and biomedical fields for nanocomposite fabrication.

Synthesis and characterization of human bone-like hydroxyapatite using Schiff's base

Hydroxyapatite (HAp) has prospective applications in the field of biomaterials as it has good biocompatibility and mechanical reliability. HAp has been synthesized using surfactants and organic modifiers, which follow the mechanism of chelating the calcium and phosphate precursors to form the calcium phosphate mineral mimicking the mineral in native human bone. The method followed in this work exploits schiff’s base which follows the same mechanism of chelating the reactants necessary for HAp formation. Needle-like nanostructures were formed in the presence of the schiff’s base derived from salicylaldehyde and 1, 4-diaminobutane. The synthesized schiff’s base and HAp were characterized using FT-NMR, XRD and FT-IR to confirm their chemical structure and crystallinity. The cytotoxic evaluation of the synthesized HAp was performed using MTT assay with murine fibroblast (L929) cells, which proved the proliferation activity of the cells in presence of HAp was found to be directly proportional to the time of exposure and HAp concentration, hence, inferring that the synthesized HAp is not only biocompatible but also promotes cell proliferation.

Facile Fabrication of Nanostructured Microchannels for Flow Boiling Heat Transfer Enhancement

ABSTRACTFlow boiling in microchannels promises high heat transfer due to the combined effect of latent heat of vaporization and forced convection in confined spaces. However, flow boiling based miniaturized thermal management devices are limited due to instability induced dryout. While several efforts have been made to delay instabilities via advanced surface modification techniques, there is a need to expand the scope of applications by developing low-cost and scalable fabrication technologies for commonly used heat exchanger materials. In this paper, we use a facile and self-limiting chemical oxidation technique for fabricating sharp needle-like superhydrophilic CuO nanostructures within six parallel 500 × 250 µm2 microchannels spread uniformly over a 1 × 1 cm2 area in a copper heat sink. We demonstrate heat transfer enhancement with nanostructured microchannels (NSM) without any appreciable change either in the average pressure drop or the fluctuations in comparison to baseline plain wall microchannels (PWM). Analysis of the high-speed images was performed to attribute the enhancement with NSM to the presence of a capillarity-fed thin-film evaporation regime, which otherwise was absent in PWM. We believe that these results are encouraging and suggest that the heat sink geometry can be optimized to investigate the true potential of nanostructured microchannels.

Fabrication of UV photodetector using needle-shaped ZnO nanostructure arrays prepared on porous silicon substrate by a facile low-temperature method

Arrays of vertically well-aligned ZnO nanoneedles were successfully grown on seeded porous silicon substrate through electric field-assisted aqueous solution method. The surface morphologies of needle-like ZnO nanostructures were studied using field-emission scanning electron microscopy and transmission electron microscopy. Meanwhile, structural and morphological analyses displayed wurtzite nanostructures with strong c-axis oriented crystal structure and preferred (0 0 2) orientation. The photoluminescence spectra revealed intensive and sharp ultraviolet light emission at 382 nm with high intensity and low broad visible light emission in a 500–700 nm wavelength range confirming high optical quality of the formed ZnO nanoneedles. The fabrication and characterization of a metal–semiconductor–metal ultraviolet photodetector based on ZnO nanoneedles were studied. Upon exposure to 325 nm light (1.6 mW/cm2) at 3 V bias voltage, the device displayed 1.98 A/W responsivity and 10.48 photosensitivity. Furthermore, the response and the recovery times measured under these conditions were 86 and 83 ms, respectively.

Controllable process of nanostructured GaN by maskless inductively coupled plasma (ICP) etching

This work improved the anisotropically etching profile of GaN with Cl2 ICP by adjusting etching pressure and gas flow. High etching rate is achieved by lowering pressure and gas flow instead of increasing etching power. High etching power is unfavorable because it may cause physical damages on the surface. In addition, it is noticed that the material of the carrier, used for holding samples during etching, has significant effects on the morphology and profile of the etched GaN surface. A smooth and large-area GaN surface was achieved by proper ICP etching with a big piece of Si carrier; whereas, with other kinds of carriers, various nano-structures were formed on the GaN surfaces after etching. In fact, it is the etching resistance of carrier materials that impacts the surface profile of etched GaN. Needle-like and grass-like nanostructures on etched GaN surfaces were observed with Al and sapphire carriers, of which the process is very similar to RIE-grass or black-silicon technology. This controllable maskless dry-etching process for the GaN nanostructured surface may show more potential applications in GaN devices.

Sonochemical assisted synthesis MnO2/RGO nanohybrid as effective electrode material for supercapacitor

Manganese dioxide (MnO2) needle-like nanostructures are successfully synthesized by a sonochemical method from an aqueous solution of potassium bromate and manganese sulfate. Also, hybride of MnO2 nanoparticles wrapped with graphene oxide (GO) nanosheets are fabricated through an electrostatic coprecipitation procedure. With adjusting pH at 3.5, positive and negative charges are created on MnO2 and on GO, respectively which can electrostatically attract to each other and coprecipitate. Then, MnO2/GO pasted on stainless steel mesh is electrochemically reduced by applying −1.1V to obtain MnO2/RGO nanohybrid. The structure and morphology of the MnO2 and MnO2/RGO nanohybrid are examined by Raman spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), field emission-scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDX), and thermal gravimetric analysis (TGA). The capacitive behaviors of MnO2 and MnO2/RGO active materials on stainless steel meshes are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge test and electrochemical impedance spectroscopy (EIS) by a three-electrode experimental setup in an aqueous solution of 0.5M sodium sulfate in the potential window of 0.0–1.0V. The electrochemical investigations reveal that MnO2/RGO exhibits high specific capacitance (Cs) of 375Fg−1 at current density of 1Ag−1 and good cycle stability (93% capacitance retention after 500 cycles at a scan rate of 200mVs−1). The obtained results give good prospect about the application of electrostatic coprecipitation method to prepare graphene/metal oxides nanohybrids as effective electrode materials for supercapacitors.

Synthesis, field emission of various ZnSe nanostructures by hydrothermal methods

In this work, grass-like, needle-like and chrysanthemum-like ZnSe nanostructures have been prepared by hydrothermal method at 200°C for 24 h successfully. With different amounts of diethanolamine, various morphologies of ZnSe formed. The structures, morphologies and crystal orientation of as-synthesised ZnSe nanostructures were characterised by X-ray diffractometer (XRD) and scanning electron microscope. The experiment result of XRD indicated that the structures of all as-synthesised ZnSe nanomaterials were cubic crystal. The field emission (FE) properties of as-synthesised samples were tested and the results revealed that the FE properties were influenced by the morphologies significantly. The FE measurement showed that the chrysanthemum-like ZnSe nanostructures had the best FE properties with a high field enhancement factor of 4328 and a low turn-on electric field of 3.4 V μm−1 among all the as-synthesised ZnSe nanostructures. The reaction mechanism of various morphologies ZnSe was also explained as follow.

The enhanced specific heat capacity of ternary carbonates nanofluids with different nanoparticles

Ternary carbonates with a relative low melting point and a high operating temperature is one of the promising heat transfer fluids for Concentrated Solar Power (CSP). In the present work, ternary carbonates nanofluids of K2CO3-Li2CO3-Na2CO3 (4:4:2, mass ratio) with nanoparticles were prepared by using a two step solution method. The specific heat capacity of ternary carbonates nanofluids with different nanoparticles (SiO2, CuO, TiO2, Al2O3) or SiO2 with different size (5, 20, 30, 60nm) were investigated. The results show that SiO2 nanoparticles are the most effective additive among of the chosen nanoparticles in enhancing the specific heat capacity of ternary carbonates. The enhancement of specific heat capacity of ternary carbonates is 78.0–116.8% in the range of 500–540°C when adding SiO2 in the range of 5–30nm. The enhancement of specific heat capacity of ternary carbonates nanofluids with CuO, TiO2 and Al2O3 are 50.6–73.9%, 31.1–56.5% and 50.6–66.5% in the range of 500–540°C, respectively. It is proved that there is no chemical reactions between ternary carbonates and the added nanoparticles. The difference in the enhanced specific heat capacity is mainly depended on the dispersive state of nanoparticles and the resulting amount of needle-like nanostructures in ternary carbonates nanofluids.

Size, morphology and optical properties of zirconia (ZrO2) nanostructures synthesized via the facile ionic surfactant-assisted solvothermal method

Zirconia (ZrO2) nanostructures, assisted by various ionic surfactants were successfully achieved via the facile ionic surfactants-assisted solvothermal method with the average crystallite size of 7.09–15.22 nm. The spherical, cauliflower-petal and needle-like nanostructures were confirmed by SEM studies and possible growth mechanisms of the nanostructures were proposed. The increasing trends of the band gap energy confirm the quantum confinement effect for the prepared samples. The strong UV emission in photoluminescence of the prepared samples indicates the high purity, perfect crystallinity and is good candidate material for optoelectronic devices.

Improving microwave absorption of the polyaniline by carbon nanotube and needle-like magnetic nanostructures

In this work, the microwave absorption of the polyaniline (PANI) was improved with various needle like magnetic nanomaterials. Several nanocomposites such as PANI–CNT, PANI–CoFe2O4, PANI–NiFe2O4, PANI–CNT–CoFe2O4, PANI–CNT–NiFe2O4 and PANI–graphene were successfully synthesized. The products were investigated by various analysis techniques such as X-ray diffraction pattern (XRD), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the products were well crystallized. Also, in order to prove the synthesis of the nanocomposites, the products were analyzed with FT-IR and Raman spectroscopy. The morphology of the products was obtained by SEM and TEM images and it was found that CNT and magnetic nanostructures were well dispersed in the polymer matrix. Magnetic properties of the products were studied by alternating gradient force magnetometer (AGFM). Microwave absorption behavior of the products was investigated in detail and it was found that PANI–CNT–NiFe2O4 nanocomposite showed the best microwave absorption behavior. In fact, when both CNT and ferrite nanostructures are added to the polymer matrix, they improve the absorption value. Moreover, the results showed that the morphology of the magnetic nanomaterials has a significant effect on the microwave absorption value. In fact, due to high active surface of needle like magnetic nanostructures, they can absorb more microwave radiation.

Autoclaving-induced in-situ grown alumina on arc-sprayed aluminum coatings: Multiscaled topography facilitates antifouling performances

Topographical morphologies of arc sprayed aluminum coatings were tailored by post-spray steam sterilization processing at 120°C. The porous needle-like nanostructures show the oxide grains of 250nm in length and 60nm in width grown on the surface of the coatings. The in-situ growth of the top alumina layer with the unique nano-patterns on aluminum coatings together with the flattened topography of aluminum formed during the spraying gave rise to a unique micro-/nano- hybrid structure. The structure and the presence of alumina synergistically offer the coatings excellent capability to inhibit effectively the adhesion of marine alga Chlorella and Phaeodactylum tricornutum. Potentiodynamic polarization testing further evidenced significantly enhanced corrosion resistance of the aluminum coatings after the autoclaving treatment. The results would give insights into processing thermal sprayed metallic coatings for desired topological structures for versatile properties.