Journal of Nano Research Vol. 49

文章题目 页数

作者: S. Nallusamy, A. Karthikeyan
摘要: Recent research scenario reveals that the amalgamations of micro and nanoceramic fillers into fiber reinforced polymer composites have improved their performances in an excellent manner. In this research work, an investigation was attempted at in analyzing the wear behavior of glass fiber reinforced with epoxy resin using granite powder as a filler material in varying weight percentage ranging from 0-5%. Structural morphology of the prepared laminates was studied using SEM. Epoxy resin which was taken as matrix material was reinforced with a combination of chopped and woven roving mat glass fibers. Pin on disc method was applied for completing the wear test at different constraints of load, sliding distance and velocity for the investigation. Influence of granite powder in the composite was synthesized by calculating the specific wear rate and weight loss occurring at varying speed and normal load were applied on it. On examining by SEM worn surface wear rate of the prepared laminate at 5 wt% of granite provided better wear resistance as compared to other compositions and characterizations of worn surfaces.
作者: Elaheh Moghaddam, Amir Ali Youzbashi, Asghar Kazemzadeh
摘要: Recent advances in nanomaterials have been led by new synthetic methods that provide control over size, morphology and crystal quality of materials. The present study is tried to discuss the effect of ultrasonic waves on characteristics of ZnO quantum dots by study of UV absorption, photoluminescence spectroscopy, X ray diffraction patterns, transmission electron microscopy and growth stages of two samples prepared by sonochemical and conventional methods. The results demonstrated that the quantum dots synthesized under ultrasonic waves were of smaller size with more narrow size distribution. Also, improvement of their crystal quality was inferred from investigation of visible emission intensity. The use of ultrasonic waves caused the phase purity of nanocrystals obtained by complete conversion of precursors into ZnO. Further, the study of their growth stages indicated that the rapid nucleation and nucleation growth were followed by Ostwald ripening process which improve the crystal properties. The better crystal quality of ultrasonic prepared ZnO indicated the enhancement of its applicability to be used for optoelectronic applications.
作者: Bing Ye Zhang, Yu Jun Wang, Lu Han, Yong Xiang Li, Ai Min Liu
摘要: Thin Al2O3 films were deposited on p-type black silicon (b-Si) by using chemical liquid phase deposition (CLD) technique. The influence of annealing temperatures on the structural and optical properties of Al2O3 films was investigated. The b-Si with 80-nm Al2O3 films exhibits a low total reflectance of 5%. The sample annealed 300 °C exhibits negative fixed charge with the density of 1.5×1012 cm-2. With the increasing of annealing temperature, negative shift of C-V curve was observed, indicating the polarity of fixed charge changes to positive, with maximal the density of 8.7×1011 cm-2. The evolution of the polarity of fixed charge is assigned to the decreasing of O: Al ratio caused by the transition of the crystalline type of Al2O3. The change of fixed charge polarity in Al2O3 provides a feasible route for both p- and n-type Si passivation in Si solar cells by adjusting the thermal post-treatment.
作者: Xiao Fei Niu, Fu Rong Tu
摘要: The monodisperse popcorn-like CeO2 nanostructures with crude surface covered by wrinkles completely and a diameter of 150-300 nm have been successfully synthesized by a facile hydrothermal technology. XRD, SEM, XPS, Raman scattering and M-H curve were employed to characterize the samples. The results showed that the popcorn-like CeO2 nanostructures have a cubic fluorite structure and there are Ce3+ ions and oxygen vacancies existing in their surface. The magnetic measurement indicated that the popcorn-like CeO2 nanostructures possess excellent ferromagnetism at room temperature, which can be attributed to the influences of the morphology of the particles, Ce3+ ions and oxygen vacancies.
作者: Hong Chan Lee, Kyoung Bo Kim, Moo Jin Kim
摘要: To integrate circuits into the organic light emitting diode displays, it is necessary to fabricate polycrystalline silicon (poly-Si) based thin-film transistors (TFTs) on the glass substrates. In this work we investigated the correlation between the electrical characteristics and the poly-Si morphology of the excimer laser annealed (ELA) TFTs in ultralow oxygen concentrations (~ ppm). The main feature of ELA poly-Si films is the protrusion at grain boundaries that makes the film surface rough. The surface roughness increases with an increasing oxygen concentration during the laser annealing and degrades the TFT characteristics in the on-state as well as the breakdown voltage of the gate insulator, while the off current is independent of process conditions. This result is attributed to the increased oxygen incorporation in the film in the case of an ELA process. Since oxygen increased the defect density in the polysilicon bandgap, controlling the oxygen concentrations in the process chamber helped to improve the performance of the ELA poly-Si TFTs. Based on these results, we discuss the relationship between performance of active matrix organic light emitting display panels and oxygen concentrations during ELA.
作者: Aminu Ishaka, Maznah Ismail, Mustapha Umar Imam, Rozi Mahmud, Ismaila Muhammad Sani, Zuki Abu Bakar Zakaria
摘要: Policosanol, a mixture of long-chain alcohols found in animal and plant waxes, has several biological effects. However, it has a bioavailability of less than 10%. One of the ways of improving bioavailability is by nanoemulsion formulation. We developed rice bran wax policosanol nanoemulsion (npol) using high-pressure homogenization. Even though earlier toxicological studies did not show policosanol-related toxicity, it is an essential part of the development of the therapeutic formulation to evaluate its toxicity status. In this study, in vitro, in vivo toxicity, and irritation and anti-irritation potential of the npol were evaluated. 3T3-L1 cells and Sprague Dawley rats were treated with npol in the in vitro and acute oral toxicity tests; while the Hen’s Egg Test Chorio-Allantoic membrane (HET-CAM) was used to test for its irritation and anti-irritation potential. npol at 2mg/mL showed lower toxicity to 3T3-L1 cells by MTT assay compared to the same concentration of policosanol after 24 (60 and 50% viabilities), 48 (62 and 58% viabilities), and 72 (110 and 89% viabilities) hours, respectively. npol was non-irritant and has slightly anti-irritant potential based on the HET-CAM test. There was also no significant toxicity to a limit test dose of 40 ml/Kg body weight of npol (containing 2000 mg/Kg body weight of policosanol) in acute oral toxicity test on Sprague-Dawly rats. The results suggest that policosanol nanoemulsion is a safe formulation devoid of toxicity and irritation potential.
作者: Dauda Abubakar, Naser Mahmoud Ahmed, Shahrom Mahmud
摘要: The synthetic NiO nanostructures have been grown using thermal wet oxidation of metallic Ni thin films on ITO/glass by RF sputtering. The deposited Nickel thin films layer were oxidized in stream atmosphere at varying temperatures range of 400 °C to 700 °C inside furnace. Structural, surface morphology, electrical and the optical properties of NiO nanostructure were analysed by X-ray diffraction (XRD), Field effect scanning electron microscope (FESEM), energy dispersive X-ray (EDX), hall effects measurements and UV-Visible spectroscope measurements. XRD analysis proves that the NiO nanostructure has a cubic structure with orientation of the most intense peak at (200), and the film prepared 600 °C shows a better crystalline quality. FESEM and AFM results also prove that by increasing the oxidation temperature, the dimensions and roughness of the NiO nanoparticle thin layer increases. Also the oxidation rate appears higher. The optimum temperature for synthesizing high quality NiO with great stoichiometric and crystalline property was determined to be at 600 of wet oxidation. EDX results reveals only O and Ni present in the treated samples, indicating a pure NiO composition obtained. From UV-Vis absorption spectroscope of Tauc’s relationship, the bang gap was observed to increase with temperature at range of 3.29 – 4.09 eV. The effect of annealing was highlighted on the tunability of electrical property Ni thin films with both n-type and p-type behavior NiO as determine from hall measurement. The observed tunability of NiO thin film will ease way toward p-n homojunction realization for optoelectronic device applications of short wave length that involves photodetectors and LEDs
作者: Bang Chao Deng, Ai Qing Zhang
摘要: A series of well dispersed ruthenium nano-clusters using Polyvinylpyrrolidone (PVP) as stabilizer were synthesized by seed-mediated method. In this method, polymer-stabilized PVP-Ru nano-cluster with a diameter of about 3.14 nm was prepared by the reduction of RuCl3 in ethylene glycol and used as a seed solution (S), which was then added to the EG solution of ruthenium (Ⅲ) salts (E) to control the size of the Ru nano-cluster synthesized in this seed-mediated method. The influences of the amount of S solution that was added to E solution and the existence of PVP in ruthenium salts solution on the size of Ru were studied in this essay. Compared with the seed solution, the size of Ru nano-cluster increased with the decreasing of the amount of seed solution added. Moreover, the existence of PVP in the EG solution of ruthenium salts would hinder the Ru nano-cluster from growing since PVP will weaken the ability for newly formed Ru0 to regrow on the seed crystal.
作者: Dauda Abubakar, Naser Mahmoud Ahmed, Shahrom Mahmud, Nabeel Z. Al-Hazeem
摘要: Nickel oxide nanoflakes have been synthesized by chemical bath deposition. The films have been deposited on ITO/glass substrate and anneal at different temperature in furnace. Surface morphology, structural and optical properties of the nanoflakes films were examined and analysed. FESEM result shows that the NiO/Ni(OH)2 film shown an increase in the thin film roughness with temperature. The film was formed with the growth of porous net-like structure that was made up of interconnected nanoflakes’ wall with a thickness of 25–45 nm for the as-grown and annealed thin film samples. The atomic ratio and weight of sample treated at 250 °C approaches the stoichiometric value. XRD analysis demonstrated that the NiO nanoflakes consist of a rhombohedral structure with orientation peak of (110), (202) and (211). This appears with more stronger intensity at 250 °C. Likewise the PL and XRD result confirms the absence of Ni(OH)2 at 250 and 350 °C of annealing temperature. From the results analysis of this work the optimum temperature for synthesizing high stoichiometric and crystalline quality of NiO nanoflakes was consider to be at 250 °C from the characterisation result analysis.
作者: Bo Pang, Xiang Xi Meng, Yang Long Hou, Hong Fang Sun, Qiu Shi Ren
摘要: The synthesis of anisotropic branched gold nanoparticles remines to be challenging as their arm number and arm length could hardly be controlled, greatly limited their biomedical application. We report the large-scale high-yield synthesis of PdCu@Au tripods, and, for the first time, their two-photon luminescence properties with quantitative characterization of the two-photon action cross section as well as quantum yield. By introducing nitrogen protection to the synthesis of the PdCu bimetallic cores, this approach eliminates the oxidative etching caused by oxygen in the air, providing a 2.5 times higher synthetic yield of 70.4 %, which enables the large-scale preparation of PdCu@Au at ca. 380 mg per batch. By the conformal coating of PdCu bimetallic cores, the PdCu@Au tripods are prepared with a purity of >90 % with average arm length 45.3 ± 5.6 nm that is ideal for biomedical applications. The PdCu@Au tripods demonstrate a much brighter two-photon luminescence than that from Au nanorods, with a 3.6 ± 0.9 times larger two-photon action cross section and comparable quantum yield. Our result also shows the two-photon luminescence property of PdCu@Au tripods could be tuned by their distinct localized surface plasmon resonance property and, in turn, the different amount of Au coating. This tunability could be explained by the recently-proposed two-step excitation mechanism of two-photon luminescence in Au nanoparticle. The folate-targeted in vitro two-photon luminescence imaging of MDA-MB-435 breast cancer cells were also demonstrated to show the great potential using PdCu@Au tripods as novel multi-functional platforms for cancer theranostics.