Micro & Nano Letters
Volume 15, Issue 7, 17 June 2020
Volumes & issues:
Volume 15, Issue 7
17 June 2020
Erbium-doped barium titanate/hydroxyapatite composites with enhanced piezoelectric and biological properties
- Author(s): Cong Wu ; Yufei Tang ; Kang Zhao ; Mengzhen Jiao ; Zixiang Wu
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 421 –424
- DOI: 10.1049/mnl.2019.0809
- Type: Article
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Shortening the period of bone repair based on BaTiO3/hydroxyapatite(HA) composites with osteoconductivity and osteoinductivity is important. However, when the piezoelectric properties of composites are matched with natural bone, the content of non-degradable BaTiO3 needs to reach 90%, which may not conducive to clinical application. The barium titanate content in the composite was reduced by doping Er3+ into the BaTiO3 of BaTiO3/HA composites with enhanced piezoelectric properties. The piezoelectric constant and compressive strength of composites increased with the increase of Er3+-doped barium titanate (BTEr) content. Appropriate piezoelectric stimulation can promote the growth of osteoblasts. 70% BTEr/30% HA is more beneficial to the proliferation of osteoblasts than 70% BaTiO3/30% HA.
Drug delivery system and in vitro release of luteolin based on magnetic nanocomposite (Fe3O4@ZIF-67)
- Author(s): Yuqiong Shi ; Beibei Qiu ; Xiangrong Wu ; Yuxuan Wang ; Jinhua Zhu ; Xiuhua Liu ; Dongbao Zhao
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 425 –429
- DOI: 10.1049/mnl.2019.0671
- Type: Article
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To extend the wide application range of luteolin (LUT), a slow-release drug delivery system is urgently needed. In this work, Fe3O4@ZIF-67 was reported as the carrier of LUT. A facile synthesis method of Fe3O4@ZIF-67 was established with simply continuous stirring. The structure and function of the nanocomposites were characterised by SEM, TEM, XRD, FTIR, VEM and TGA. Under the optimal reaction conditions, the maximum drug loading capacity of the carrier was obtained to be 308.07 µg/mg. And LUT was released about 55% from Fe3O4@ZIF-67 after 72 h. The adsorption kinetics and release kinetics of LUT were also investigated. The results showed that the relationship between time and drug loading fitted well with the quasi-second-order kinetic equation (R 2 = 0.99) and the release mechanism followed the Sigmoidal model (R 2 = 0.98). In short, Fe3O4@ZIF-67 could be developed as a carrier of the LUT delivery system for slow release.
Solution combustion synthesis and sorption properties of nanoscale amorphous AlPO4
- Author(s): Jiahai Bai and Jiasi Piao
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 430 –432
- DOI: 10.1049/mnl.2019.0771
- Type: Article
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430
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Nanoscale amorphous AlPO4 was synthesised via a solution combustion process using C2H5NO2 (glycine) as fuel and NH4NO3 as oxidant. The effects of molar ratios of C2H5NO2 to NH4NO3 on characteristics and sorption properties of the amorphous AlPO4 were also studied. The experimental results showed that the Brunauer–Emmett–Teller specific surface areas of the amorphous AlPO4 and the sorption capacities of Pb2+ ions on AlPO4 decreased appreciably with the molar ratio of C2H5NO2 to NH4NO3 varying from 1:9 to 1:12, while the average particle size of the amorphous AlPO4 exhibited no appreciable change.
Synthesis and characterisation of zeolite LTA with sheet structure
- Author(s): Peng Wang and Qi Sun
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 433 –436
- DOI: 10.1049/mnl.2019.0793
- Type: Article
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This work reports a simple and effective method for the rapid synthesis of zeolite Linde Type A (LTA) with sheet structure from kaolin. X-ray diffraction results confirm the purity and crystallinity of the synthesised zeolite LTA with sheet structure. Transmission electron microscopy images clearly show the sheet-like structure of the synthesised zeolite LTA. The selected area electron diffraction pattern indicates that the crystal structure type of the synthesised zeolite LTA with sheet structure is the body-centred cube. Meanwhile, the elemental mapping confirms the coexistence and uniform distribution of Si, Al, O and Na elements in the lamellar structure of the synthesised zeolite LTA. In addition, N2 adsorption–desorption technique indicates that the surface area of the synthesised zeolite LTA with sheet structure increases up to 39.7994 m2·g−1, a much higher value than that of zeolite LTA.
Photomechanical actuation of polydimethylsiloxane/carbon black nanocomposite
- Author(s): Shivashankar Hiremath and Satyabodh M Kulkarni
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 437 –440
- DOI: 10.1049/mnl.2019.0286
- Type: Article
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Materials such as carbon black (CB), carbon nanotube, graphene, etc. have been found to deform on exposure to the light source. Introducing these materials into polymers could convert them to photo-responsive composites. This is demonstrated by the experiment in which polydimethylsiloxane (PDMS) polymer containing CB nanofiller composites is prepared, and its photomechanical actuation from exposure to IR light source is recorded using a laser displacement sensor. The particle size analysis reveals the size of the CB, which is verified by the dynamic light scattering method. The UV–vis–IR spectrophotometer study shows that an increase in the light absorbance capacity of nanocomposites compared to the plain polymer. The PDMS/CB nanocomposite beam exhibited a significant deformation compared to plain PDMS. Deformation of the order of 10–11 mm is observed for a given IR source. The deformation found to have good repeatability but with some thermal hysteresis in cyclic actuation and de-actuation.
Preparation of CuO@PPy hybrid nanomaterials as high cyclic stability anode of lithium-ion battery
- Author(s): Lili Feng ; Wei Zhang ; Rui Wang ; Linan Xu ; Dongzhi Li ; Congli Xiao ; Yinyin Zhang
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 441 –445
- DOI: 10.1049/mnl.2019.0409
- Type: Article
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Over the recent 20 years, numerous researches have focused on the lithium-ion batteries anodes of MOx 3d-metal oxides which have a high specific capacity. For example, the specific capacity of CuO material as an anode is ∼670 mAh g−1. Unfortunately, serious capacity degradation limits their promising applicability. To improve cyclic stability, PPy is covered on CuO surface to prepare CuO@PPy core–shell hybrid materials by chemical polymerisation. Pyrrole amount plays an important role on control the PPy shell thickness. After PPy coating, the lithium-ion battery cycling stability and coulombic efficiency have been improved greatly, and CP-5 sample has the best cyclic stability and coulombic efficiency. The capacity retention of bare CuO is only 27.9% after 200 cycles. By contrast, the capacity retention of CP-5 sample is ∼100%. The flexible conducting polymers shell (PPy) lead to improved cyclic stability. These results give a strategy to solve MOx 3d-metal oxide capacity degradation as Lithium-ion batteries anode.
Experimental study of the effect of surface groove micro-texturing on lubrication characteristics
- Author(s): Huichao Gao and Xinyuan Chen
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 446 –450
- DOI: 10.1049/mnl.2019.0361
- Type: Article
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This study investigated the effect of surface groove micro-texturing on hydrodynamic lubrication characteristics. All textured samples were processed by laser; non-textured reference samples were also created for comparison. Four types of surface groove patterns with different groove angles and groove depths were utilised. Different rotational speeds and gaps were used in the experiment to explain the relationship between the load-carrying capacity and the groove texture parameters under different conditions. The results suggested that the load-carrying capacity was greatly influenced by the operational conditions and that the samples with surface groove textures generated a larger hydrodynamic lift force than the non-textured samples.
Fix of Zn species in silicalite-2 via a facile crystallisation process control route
- Author(s): Qingjun Yu ; Xiaolong Tang ; Honghong Yi
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 451 –454
- DOI: 10.1049/mnl.2020.0018
- Type: Article
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Zinc species were fixed in the silicalite-2 zeolite by a crystallisation process control method. By controlling the introduction time of Zn during the crystallisation process, the distribution of Zn species in zeolite crystals can be facilely adjusted. Particularly, as Zn species were introduced after the completion of nucleation or crystal growth, crystals with structure of silica–core and Zn–silica shell will be formed. The ratio of shell to core thickness can be easily varied by adjusting the Zn feeding time as well as controlling the recrystallisation period.
Molecular dynamics approach to thin-film liquid phase change phenomena on functionally gradient wettability surface
- Author(s): Md Shajedul Hoque Thakur ; Mahmudul Islam ; Shahriar Alam ; Mohammad Nasim Hasan ; Yuichi Mitsutake ; Masanori Monde
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 455 –460
- DOI: 10.1049/mnl.2019.0657
- Type: Article
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An atomistic model of functionally gradient wettability (FGW) surface for molecular dynamics (MD) simulation has been proposed and developed. Using the present model, a non-equilibrium MD study has been conducted to investigate the effects of FGW on liquid thin film phase change characteristics over the FGW surface. A power function has been considered as the wettability governing function of the FGW surface and by varying its function parameter, various FGW surfaces have been studied. The simulation results show that the function parameter can be a significant modulation parameter for heat transfer characteristics associated with the phase transition. To gain insight into any additional heat transfer mode associated with the FGW surface, the wall heat fluxes have been compared with linear mixture rule predictions. It is found that, along with conduction heat transfer through the interface between solid FGW surface and liquid thin film, there exists convective heat transfer along the wettability gradient direction. This additional heat transfer mode, which is not present for uniformly wetted surfaces, causes significant enhancement of phase change characteristics. The results of the present MD simulation have been found consistent with macroscopic prediction based on classical thermodynamics theory.
Low-temperature oxidation of metal nanoparticles obtained by chemical dispersion
- Author(s): Ella L. Dzidziguri ; Elena N. Sidorova ; Jansaya E. Yahiyaeva ; Dmitriy Yu. Ozherelkov ; Alexander A. Gromov ; Anton Yu. Nalivaiko
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 461 –464
- DOI: 10.1049/mnl.2019.0706
- Type: Article
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461
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Oxidation of cobalt, nickel, molybdenum and tungsten nanoparticles under prolonged exposure in the air was studied. Nanoparticles were obtained by chemical dispersion with the following reduction temperatures: 200–400°C for cobalt; 200–400°C for nickel; 700–800°C for molybdenum and 750–850°C for tungsten. Scanning electron microscopy, transmission electron microscopy, XRD and thermogravimetric analysis were used for nanoparticles characterisation. The average size of nanoparticles, specific surface area and the coherent scattering area were determined. The method for oxide film thickness calculation on the surface of the nanoparticles was proposed and confirmed its adequacy. Based on experimental data, the growth law of the oxide film on the studied nanoparticles was determined. The obtained results can be used in the certification of nanoparticles and evaluation of a highly dispersed metal powders shelf life.
Rapid hydrothermal method for the preparation of carbon quantum dots in the presence of hydrogen peroxide
- Author(s): Jin-Lan Qin ; Shan-Ji Li ; Ning-Ning Yuan ; Ying Chen ; Bing-Fu Lei ; Chao-Fan Hu ; Ying-Liang Liu
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 465 –468
- DOI: 10.1049/mnl.2019.0529
- Type: Article
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Carbon quantum dots (CQDs) have been studied for years as one of the most promising fluorescent nanomaterials. Herein, CQDs were prepared rapidly by a simple, eco-friendly one-pot hydrothermal method in the presence of hydrogen peroxide. Different sizes of CQDs are obtained by changing the reaction time. X-ray photoelectron spectroscopy and Fourier transform infrared spectrometry demonstrated the existence of a large number of oxygen-containing groups on the surface of CQDs. The as-prepared CQDs exhibited bright yellow luminescence under UV light, they are applied for bioimaging of HeLa cells, and showed bright luminescence and excellent biocompatibility.
Fluorescence enhanced detection of water in organic solvents by one-pot synthesis of orange-red emissive polymer carbon dots based on 1,8-naphthalenediol
- Author(s): Meiling Yang ; Mingwang Liu ; Zipeng Wu ; Yu He ; Yili Ge ; Gongwu Song ; Jiangang Zhou
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 469 –473
- DOI: 10.1049/mnl.2019.0170
- Type: Article
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A facile method for fabricating polymer carbon dots (PCDs) with characteristic dual-emission at 570 and 620 nm by 1,8-naphthalenediol in n-propanol solvents was designed. The synthesised PCDs possessed fluorescence enhancement performance toward the water in organic solvents. Based on this peculiar phenomenon, a highly efficient fluorescent probe for water detection in organic solvents such as N,N-dimethylformamide, dimethyl sulfoxide and n-propanol was established with a wide detection range from 0 to 50%. The probe can also be utilised to determine water content in other organic solvents. The practical application was explored by studying the response of PCDs toward the water in various spirit samples. This method may offer a new way of detecting water in organic solvents by PCDs.
Aluminium alloy processed by square-column composite structure and its anti-icing characteristics
- Author(s): Yanling Wan ; Meng Zhang ; Bin Dong ; Huadong Yu
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 474 –479
- DOI: 10.1049/mnl.2019.0171
- Type: Article
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To prepare surfaces with stable anti-icing properties, square-column micro/nanocomposite structures were fabricated using wire-cut electrical discharge machining. Smooth and hydrophobic/superhydrophobic surfaces were tested for wettability and were subjected to mechanistic analysis. Droplets were found to produce an ‘air cushion effect’ upon contact with the microstructure, which reduced the contact area between the droplets and the aluminium substrate and increased the contact angle of the droplets on the surface. The icing experiment quantitatively evaluated the anti-icing performance of the surfaces by observing the cooling time and out-of-phase icing time of water droplets. It was found that the anti-icing effect is influenced by the wettability of the material and that the superhydrophobic surface has excellent anti-icing properties. Combined with the one-dimensional heat transfer theory for analysing the mechanism of icing, the results show that the ‘air cushion’ reduces the heat transfer between the solid and liquid and increases the thermodynamic barrier to ice core formation. The stability of the sample surface was tested by icing-melting experiments and friction experiments, and the test piece exhibited stable wettability and anti-icing performance.
Optical constants of gamma-irradiated silver-doped PVA in the near-infrared range
- Author(s): Mohamed Salah ; Michael Gad ; Mohamed Elkattan ; Yasser Sabry
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 480 –485
- DOI: 10.1049/mnl.2019.0800
- Type: Article
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Pure and gamma-irradiated silver-doped polyvinyl alcohol ‘PVA’ samples are fabricated, and their optical constants are experimentally determined through the measurement of the reflectance and the transmittance. Using the thin-film model, an iterative method is used to solve for the real and imaginary parts of the refractive index, in the near-infrared (NIR) region. The retrieved refractive index values are verified through a comparison between the theoretical calculations and the practical measurements of the transmittance. The refractive index shows a big increase in the absorption loss of the polymer, when compared to pure PVA. This qualifies the fabricated films for new applications such as optical plasmonic circuits, optical absorbers, solar energy harvesting and sensors in the NIR region. More insight on the functional groups that exist in the fabricated specimens is given by Fourier transform spectroscopy in the mid-infrared range from 400 to 4000 cm−1.
Synthesis of antibacterial flower-like silver nanostructures by self-assembly of diphenylalanine peptide on graphite
- Author(s): Alireza Allafchian ; Seyed Hosein Mousavi ; Seyed Amir Hossein Jalali
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 486 –489
- DOI: 10.1049/mnl.2020.0076
- Type: Article
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Preparation of silver nanoflowers (Ag NFs) was carried out through the self-assembly process of diphenylalanine (FF) peptide on the graphite surface. Pencil graphite rods were used as a substrate for the self-assembly process. A reduction reaction by hydrazine was employed in the synthesis procedure of the Ag NFs. scanning electron microscope, Fourier transform infrared spectroscopy (FT-IR) spectroscopy and X-ray diffraction (XRD) were employed to characterise the obtained Ag NFs. The morphological analysis of the Ag NFs revealed assemblies constructed by multiple sheet nanostructures designed as flower petals and positioned in the form of 3D semi-spherical arrangements. The successful synthesis of Ag NFs was confirmed by FT-IR characteristic bands of FF and Ag components. The cubic lattice structure of the Ag NFs was revealed by XRD. Standard Kirby–Bauer disk diffusion tests using Gram-positive and Gram-negative bacterial strains exhibited the promising antibacterial performance of the Ag NFs against all of the tested bacterial species.
Photocatalytic properties of ZnO thin film with different morphologies from seed, array to grass
- Author(s): Zhaopeng Wang ; Xiaoyun Ye ; Long Chen ; Leilei Zhang ; Qianting Wang ; Lian Ma ; Nengbin Hua
- Source: Micro & Nano Letters, Volume 15, Issue 7, p. 490 –494
- DOI: 10.1049/mnl.2020.0017
- Type: Article
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ZnO thin film with different morphologies from seed, array to grass was grown by simple aqueous solution method under room temperature. The morphologies, structure, optical properties and photocatalytic properties of the samples were characterised by transmission electron microscope, scanning electron microscope, X-ray diffraction, fluorescence spectrometer, UV–Vis spectrophotometer and photocurrent response. The results showed that the ZnO arrays and grassy ZnO were both hexagonal wurtzite with uniform distribution and regular growth on the glass substrate. ZnO thin film with different morphologies affected the utilisation efficiency of the ultraviolet light. Multiple light reflections inside the grassy ZnO greatly increase the light efficiency. The methyl blue degradation rate of grassy ZnO photocatalyst was superior under the UV light compared to the other ZnO morphologies. Grassy ZnO showed favourable stability after five cycles. The comparison of the ZnO semiconductor in different dimensions is helpful for further research on other photocatalysts as well as their potential application.
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