Nanoscience and Nanotechnology Letters

Description

Nanoscience and Nanotechnology Letters (NNL) is a multidisciplinary peer-reviewed journal consolidating nanoscale research activities in all disciplines of science, engineering and medicine into a single and unique reference source. NNL provides the means for scientists, engineers, medical experts and technocrats to publish original short research articles as communications/letters of important new scientific and technological findings, encompassing the fundamental and applied research in all disciplines of the physical sciences, engineering and medicine.

  • Impact factor
    1.44
  • 5-year impact
    0.89
  • Cited half-life
    1.60
  • Immediacy index
    0.31
  • Eigenfactor
    0.00
  • Article influence
    0.21
  • Website
    Nanoscience and Nanotechnology Letters
  • ISSN
    1941-4900
  • Document type
    Journal

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Donor states of Sn dopants and electronic structures in Sn-doped ZnO nanobelts have been investigated by combining temperature-dependent photoluminescence (PL) and first-principles calculations. The strong and dominant donor-bound exciton (D0X) emission was observed in lowtemperature PL spectrum of Sn-doped ZnO nanobelts. The D0X emission has thermal activation energy of ∼12 meV and the corresponding ionization energy was determined to be ∼60 meV, which is derived from shallow donor nature of Sn dopants. In addition, the D0X peak dissociates into a neural-donor-like defect-pair complex and band-to-band transition with increasing temperature. As a result, the near-band-edge emission peak at room temperature is ascribed to a mixture of band-to-band and free-to-bound transition. Furthermore, first-principles electronic structure calculations indicate that Sn substituting Zn site in ZnO is a rather shallow donor, in good agreement with the PL results.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: Nax CoO2 thin films dispersed with Au nanoparticles have been grown on c-Al2O3 substrates by a two step method and their high temperature thermoelectric properties have been investigated. Firstly, CoO films embedded with Au nanoparticles were obtained by pulsed laser ablation a Co3O4 ceramic target attached with Au plate. Then the CoO/Au composite thin films were annealed in Na vapor at high temperature to form the Nax CoO2/Au composite thin films. X-ray diffraction measurements revealed that the resulting Nax CoO2 film was c-axis oriented with perfect ab-plane alignment and there was no reaction between Au and Nax CoO2. The thermoelectric measurements showed that the incorporation of Au nanoparticles into Nax CoO2 film matrix leaded to a decrease in resistivity of the films without obviously deteriorating the Seebeck coefficient. Overall, an improvement of ∼70% in power factor was achieved at 800 K for the 10 wt.% Au-added Nax CoO2 thin film sample. The results demonstrated that adding Au nano-sized particles is an effective way to improve the thermoelectric power factor of Nax CoO2 films.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: A series of activated carbons with various structures have been prepared by KOH activation of coconut shell. Textural characterization results using N2 adsorption/desorption analysis at 77 K showed that the pore development highly depended on the ratio of the activating agent to carbon precursor. Methane uptake by multi-walled carbon nanotubes (CNTs) synthetized from various activated carbon-supported catalysts was investigated at 298 K and pressures up to 5.0 MPa using a volumetric method. The pore size distributions, specific surface areas and micropore volumes of the CNTs were characterized by N2 adsorption/desorption isotherms. It was obtained that the activated carbon with higher specific surface area produced the CNTs with smaller specific surface area. The model isotherms such as Langmuir and Dubinin–Astakhov (D–A) were examined to fit the uptake data. It was concluded that the high specific surface area and micropore volume of the adsorbents did determine methane uptake capacity. Heat of adsorption was evaluated based on the Clausius–Clapeyron equation. Small values of heat of adsorption confirmed the physical nature of the adsorption process.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: The structural characteristics of Ga2O3 nanowires and the sensitivity of Ga2O3 extended gate field effect transistor (EGFET) pH sensors are investigated. The Ga2O3 nanowires are prepared using a vapor–liquid–solid (VLS) mechanism. The results show that the nanowires correspond to β-Ga2O3 phase and single crystals. The β-Ga2O3 nanowires were active materials in the EGFET pH sensor. The resulting EGFET pH sensor containing β-Ga2O3 nanowires exhibits high detection of properties (14 μA· pH–1. The β-Ga2O3 nanowires are a candidate material for pH sensor.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: Deposition of acid oxidized multiwall carbon nanotubes (MWCNTs) onto commercial glass fibers (GFs) is achieved by a simple dipping deposition procedure. Given the interaction between the chemical groups of the fiber coating (sizing) and those of the oxidized MWCNTs, a homogenous deposition of MWCNTs onto GFs is achieved only when the fiber coating is maintained. The MWCNTs are deposited homogeneously over the GFs not only at the microscale, but also at the macroscale. The homogeneous distribution of the MWCNTs over the GF is characterized by the intensity of the Raman bands as a function of the position on the fiber.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: Using selenium dioxide as the source of selenium, CdSe, CdSe/ZnS and Ce doped CdSe/ZnS nanocrystals were synthesized. The X-ray diffraction analysis confirmed that the synthesized CdSe and CdSe/ZnS materials were both hexagonal phase. SEM techniques were employed for the study of the morphology of hexagonal CdSe and CdSe/ZnS samples. Our study focused on the optical properties of the Ce-doped CdSe/ZnS material. The PL spectra of the Ce-doped CdSe/ZnS material had two emission peaks at 511 nm in the green region and 700 nm in the red region, respectively. Our Ce-doped CdSe/ZnS nanocrystals could be combined with blue InGaN/GaN chip to fabricate white LED.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: Metal catalyst sometimes is entrapped in crystalline silicon (Si)/amorphous Si-oxide nanowires. Till now, however, the entrapping mechanism is still unclear. In this work, Si/Si-oxide nanowires were grown via thermal annealing of a Si wafer coated with a 10 nm thick layer of gold (Au) which acts as catalyst. Au nanospheres or elongated core are occasionally entrapped in the nanowires. Transmission electron microscopy, energy dispersive X-ray spectroscopy and selected area electron diffraction were employed to study the structure of the grown nanowires and their relationship with the seeding Au particles. The entrapment of the Au catalyst is attributed to the eutectic precipitation of Au and Si in the Si-supersaturated Au–Si–O droplet as the temperature is below the eutectic point. A new mechanism elucidates the entrapping process.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: A low power and energy efficient CMOS integrated smart temperature sensor is described and investigated in this paper. The bipolar junction transistor-based sensor employs an energy-efficient 2nd-order, cascaded-integrator and feed-forward delta-sigma analog-to-digital converter with a 12-bit accuracy. The sensor occupies only 0.26 mm2 in a 180 nm CMOS process. The whole system accuracy is guaranteed by the extensive use of current gain cancellation, analog dynamic element matching, and chopper stabilization circuitry. After a two-point temperature calibration, the sensor operates from –40 °C to 120 °C with a resolution of 0.1 °C and an inaccuracy of 0.4 °C. Moreover, the designed sensor only consumes 9 W from a 1.8 V supply at room temperature.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: A new formulation based on experimental data for predicting enhanced thermal conductivity is introduced for high temperature gradient. This methodology incorporates the role of brownian motion which induces convection in nanoparticles and the correction in thermal conductivity due to variation of expansivity of nanofluid with temperature. Model equation consist of the dependence of volume fraction, size, density of the nanoparticles and the physical properties of base fluid. We have taken a nanofluid of different size nanoparticles containing Cu, CuO, Al2O3 in water and EG (ethylene glycol) as a base fluid. The results obtained are compare with experimental data of different nanofluids showing a nice consonance with model. Other theoretical model from the archival literature are also compared, but the currently developed model shows better resuts with high veracity and precision.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: The monoclinic CuO nanosheet arrays, disk-like and sheaf-like CuO have been synthesized on Cu substrate by a facile solution route in absence of surfactant at room temperature (20 °C). The thickness of sheets and morphology of CuO can be tuned by the concentration and kind of alkali. A plausible growth mechanism was proposed to account for the formation of the nanosheet arrays. Due to the different rate of nucleation and crystal growth the morphology of CuO changed with the concentration of OH– when the same alkali metal hydroxide was used during reaction. The ionic radius of alkali metal hydroxide utilized to generate [Cu(OH)4]2– ions significantly influenced the morphology of CuO. The different cation radius has different charge density, which causes the different formation rate of the copper oxide precipitates.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: Carbon nanotubes (CNTs) with its exceptional thermal and mechanical properties hold the promise of delivering high performance nanocomposite materials. To utilize CNTs as effective reinforcement in metal nanocomposites, appropriate dispersion and robust interfacial adhesion between individual CNT and metal matrix have to be certain. This work presents a novel combined technique of nanoscale dispersion (NSD) of functionalized multiwalled carbon nanotubes (MWCNTs) in copper (Cu) matrix composite followed by powder injection molding (PIM). MWCNTs contents were varied from 0 to 10 volume fraction. Evidences on the existence of functional groups and microstructural analysis of the fabricated nanocomposites were determined using TEM, EDX, FESEM and FTIR. Thermal conductivity and elasticity measurements were also performed. The results showed that the impurities of the pristine MWCNTs such as Fe, Ni catalyst, and the amorphous carbon have been significantly removed after sonication process. FESEM and TEM observations showed high stability of MWCNTs at elevated temperatures and uniform dispersion of MWCNTs in Cu matrix at different volume fractions and sintering temperatures (950, 1000 and 1050 C). The experimentally measured thermal conductivities of Cu/MWCNTs nanocomposites showed remarkable increase (11.25% higher than pure sintered Cu) with addition of 1 vol.% MWCNTs, while the modulus of elasticity (Young's modulus) of Cu/MWCNTs nanocomposites sintered at 1050 °C for 2 h was increased proportionally to the increment in MWCNTs contents.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10).
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    ABSTRACT: We calculate the phonons in h-boron nitride (h-BN) sheet by constructing a dynamical matrix using the force constants derived from the well known second generation reactive empirical bond order (REBO) potential by Brenner and co-workers. Our results are comparable to inelastic X-ray scattering as well as first principle calculations. For h-BN the frequencies are little lower than the corresponding ones for graphene as expected. At Γ point the optical modes (degenerate) lie near 1450 cm–1 for h-BN. The frequency regimes are easily distinguishable. The low frequency (ω → 0) modes are derived from acoustic branches of the sheet. The radial modes can be identified with ω → 600 cm–1. High frequency regime is above 1200 cm–1 (i.e., ZO mode) and consists of TO and LO modes. The present work aims to explore agreement between theory and experiment. A better knowledge of the phonon dispersion of h-BN sheet is highly desirable to model and understand the properties of boron nitride nanotubes (BNNTs). The development and production of BNNTs for possible applications need reliable and quick analytical characterization. Our results may serve as an accurate tool for the spectroscopic determination of tube radii and chirality's.
    Nanoscience and Nanotechnology Letters 07/2014; 6(7):606-611.
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    ABSTRACT: Abrupt change in the lactate concentration in children under the age of three has been related to hepatic immaturity. An electrochemical lactate biosensor was developed by successfully binding lactate dehyrogenase (LDH) onto Fe3O4 nanoparticles via nafion. Towards this design, Fe3O4 nanoparticles were synthesized by thermal co-precipitation of ferric and ferrous chlorides. The structural and morphological properties of iron oxide (Fe3O4) nanoparticles were characterized using XRD and FE-SEM respectively. Polycrystalline nature of the particles was confirmed by XRD data. The size of the spherical shaped nanoparticles was found to be 24.97±4.98 nm. FT-IR spectroscopy was used to confirm the binding of LDH to Fe3O4 nanoparticles. A lactate detecting electrochemical biosensor was developed by fabricating the modified gold electrode (Au/NanoFe3O4/LDH) with immobilized LDH on Fe3O4 nanoparticles. An appreciable linear response to lactate in the range up to 0.14 µmol L-1 was observed with the response time of < 1 s, a detection limit of 1.28 nmol L-1, quantification limit of 4.22 nmol L-1 and sensitivity of 320 nA nM-1 cm-2. Michaelis-Menten constant (K_M^app) and maximum change in current (Imax) value for the immobilized enzyme were 0.024 ± 1.3×〖10〗^(-3) µmol L-1 and 0.98 µA respectively. The developed bio-electrode with nano-interface showed a very good reproducibility and stability.
    Nanoscience and Nanotechnology Letters 03/2014; 6(3):242-249.
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    ABSTRACT: Optimal conditions for the biosynthesis of silver nanoparticles (AgNPs) by fungi Aspergillus foetidus were investigated. Condition of 0.2% salinity, 4 mM of AgNO3, pH 9, 10% diluted concentration of cell filtrate and incubation time of 72 h at 30 �C were found to be optimum for the biosynthesis of silver nanoparticles. The activity of nitrate reductase attained optimum level at 0.2% salinity, pH 9 and 30 �C. Activities of nitrate reductase in fugal cell filtrate were 0.5116 and 0.1711 �mol/ml/min, respectively, before and after the synthesis of AgNPs. The protein contents were 407.4 and 207.3 �g/ml respectively before and after the synthesis of AgNPs, and both the nitrate reductase activity and the protein content decreased after the biosynthesis of AgNPs, indicating a possible role for this enzyme in the biosynthesis of AgNPs. The rate of conversion of Ag+ to Ag0 and the concentration of the synthesized Ag0 were found to be 93.39% and 158.65 �g/ml, respectively. The minimum inhibitory concentration (MIC) of synthesized AgNPs was determined against selected plant pathogenic fungi of Aspergillus spp. and F. oxysporum, and MIC value of AgNPs in A. flavus was lowest 1.6 �g/ml.
    Nanoscience and Nanotechnology Letters 03/2014; 6(3):181-188.
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    ABSTRACT: Tuberculosis (TB) still represents one of the most overshadowing public health issues, particularly in developing countries. The efforts that are currently being made by the scientific community are many and sprout on various fronts, but can be divided in three basic avenues: development of new vaccines for prevention, generation of new and advanced diagnostic tools, and finally improvement of the chemotherapy. An “outside-the-box” approach is hence needed to develop new and improved instruments to fight Mycobacterium tuberculosis, the causative agent of TB. Cutting-edge technologies, such as nanotechnologies, can provide innovative and powerful tools to conquer this ancient infectious disease. Here, some notable examples of how nanotechnologies have entered in infectious diseases field will be presented, discussing how the “white plague,” namely the TB, can represent a paradigm of a complex infectious disease whose several aspects must be kept in consideration.
    Nanoscience and Nanotechnology Letters 02/2014; 6:134 - 138.
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    ABSTRACT: To fabricate films composed of POM functional molecules is crucial to both fundamental research and application. In the paper, a Cs2.5PW12O40 nanoparticle monolayer film was fabricated by a facile method using dodecatungstophosphoric acid (H3PW12O40) and Cs2CO3 as precursors via nanocasting route and colloidal crystal as template. The morphology, structure, and phase composition of samples were characterized by elemental analysis, XRD, UV-vis absorption spectroscopy, transmission electron microscope and scanning electron microscope techniques. This arrayed film constructed by pure cesium salt of dodecatungstophosphoric acid Cs2.5PW12O40 nanoparticles shows well dispersed distribution.
    Nanoscience and Nanotechnology Letters 01/2014; 6(5).