bluuebunny/crossref_metadata_2025 huggingface dataset:
Photovoltaic enhancement of Si solar cells by assembled carbon nanotubes
Authors: Zhang Y. F. , Wang Y. F. , Chen N. , Wang Y. Y. , Zhang Y. Z. , Zhou Z. H. , Wei L. M.
Published: October 2014

Photovoltaic conversion was enhanced by directly assemble of a network of single-walled carbon nanotubes (SWNTs) onto the surface of n-p junction silicon solar cells. When the density of SWNTs increased from 50 to 400 tubes μm−2, an enhancement of 3.92% in energy conversion efficiency was typically obtained. The effect of the SWNTs network is proposed for trapping incident photons and assisting electronic transportation at the interface of silicon solar cells.
Synthesis, characterization and biocompatibility studies of zinc oxide (ZnO) nanorods for biomedical application
Authors: Gopikrishnan R. , Zhang K. , Ravichandran P. , Baluchamy S. , Ramesh V. , Biradar S. , Ramesh P. , Pradhan J. , Hall J. C. , Pradhan A. K. , Ramesh G. T.
Published: October 2014

Nanoparticles are increasingly being recognized for their potential utility in biological applications including nanomedicine. Here, we have synthesized zinc oxide (ZnO) nanorods using zinc acetate and hexamethylenetetramine as precursors followed by characterizing using X-ray diffraction, fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. The growth of synthesized zinc oxide nanorods was found to be very close to its hexagonal nature, which is confirmed by X-ray diffraction. The nanorod was grown perpendicular to the long-axis and grew along the [001] direction, which is the nature of ZnO growth. The morphology of synthesized ZnO nanorods from the individual crystalline nucleus was confirmed by scanning and transmission electron microscopy. The length of the nanorod was estimated to be around 21 nm in diameter and 50 nm in length. Our toxicology studies showed that synthesized ZnO nanorods exposure on hela cells has no significant induction of oxidative stress or cell death even in higher concentration (10 μg/ml). The results suggest that ZnO nanorods might be a safer nanomaterial for biological applications.
Effect of hydrogen plasma treatment on the growth and microstructures of multiwalled carbon nanotubes
Authors: Srivastava S. K. , Vankar V. D. , Kumar V.
Published: October 2014

The effect of hydrogen plasma treatment of iron oxide films on the growth and microstructure of carbon nanotubes (CNTs) by microwave plasma enhanced chemical vapor deposition process has been investigated. Microwave plasma was characterized in-situ using optical emission spectrometer. Morphology of the films was examined by scanning electron microscopy. Structural analysis was carried out by high resolution transmission electron microscopy (HRTEM) equipped with energy dispersive X-ray spectroscopy (EDS) and micro-diffraction attachments. It is found that oxide films without H2 plasma pretreatment or treated for lesser time resulted in CNT films with high percentage of carbonaceous particles and with embedded particles/nanorods distributed discontinuously in the cavity of the nanotubes. The embedded particles were found to be of iron carbide (Fe-C) as confirmed by HRTEM, EDS and micro-diffraction analysis. Experimental observations suggested that the iron oxide particles had poor catalytic action for CNT growth and in-situ reduction of oxide clusters to Fe by hydrogen plasma plays a key role in discontinuous filling of the nanotubes by the catalytic particles.
Polymer light-emitting devices using poly(ethylene oxide) as an electron injecting layer
Authors: Rao M. V. Madhava , Huang Tsung-Syun , Su Yan-Kuin , Tu Ming-Lung , Huang Chun-Yuan , Wu Shang-Shung
Published: October 2014

The performance of polymer light emitting devices (PLEDs) based on polyvinyl carbazole (PVK) is improved by introducing a nanoscale interfacial thin layer, made of poly(ethylene oxide) (PEO), between the calcium cathode and the PVK emissive layer. It is believed that the PEO layer plays a key role in enhancing the device performance. In comparison to the device with Ca/Al as the cathode, the performance of the PLED with PEO/Ca/Al cathode, including the driving voltage, luminance efficiency is significantly improved. These improvements are attributed to the introduction of a thin layer of PEO that can lower the interfacial barrier and facilitate electron injection.
Identification of binding interactions between myeloperoxidase and its antibody using SERS
Authors: Papazoglou E. S. , Babu S. , Mohapatra S. , Hansberry D. R. , Patel C.
Published: October 2014

Surface Enhanced Raman Spectroscopy (SERS) is a widely used spectroscopic method that can dramatically increase the sensitivity of Raman spectroscopy and has demonstrated significant benefit in the identification of biological molecules. We report the use of SERS in differentiating the bound immunocomplex of myeloperoxidase (MPO) and its antibody from the unbound complex and its individual components. The SERS signal was enabled by gold nanoparticles attached to MPO, pAb and their immunocomplex at an excitation wavelength of 785 nm. The obtained SERS spectrum of MPO is in agreement with previous literature. Comparative SERS spectrum analysis of MPO, pAb, and their immunocomplex reveals the significant peak shifts and intensity variations caused by the conformational changes due to the immunocomplex formation. Several key areas have been identified which correspond to specific amino acids being shielded from undergoing resonance while new amino acid residues are made visible in the SERS spectrum of the immunocomplex and could be a result of conformational binding. Our work demonstrates the capability of SERS to identify binding events and differentiate an immunocomplex from its unbound components with direct applications in biosensors.
Effect of nitrogen on deposition and field emission properties of boron-doped micro- and nano-crystalline diamond films
Authors: Li L. A. , Cheng S. H. , Li H. D. , Yu Q. , Liu J. W. , Lv X. Y.
Published: October 2014

In this paper, we report the effect of nitrogen on the deposition and properties of boron doped diamond films synthesized by hot filament chemical vapor deposition. The diamond films consisting of micro-grains (nano-grains) were realized with low (high) boron source flow rate during the growth processes. The transition of micro-grains to nano-grains is speculated to be strongly (weekly) related with the boron (nitrogen) flow rate. The grain size and Raman spectral feature vary insignificantly as a function of the nitrogen introduction at a certain boron flow rate. The variation of electron field emission characteristics dependent on nitrogen is different between microcrystalline and nanocrystalline boron doped diamond samples, which are related to the combined phase composition, boron doping level and texture structure. There is an optimum nitrogen proportion to improve the field emission properties of the boron-doped films.
Label-free colorimetric estimation of proteins using nanoparticles of silver
Authors: Shrivastava Siddhartha , Dash Debabrata
Published: October 2014

Metallic nanoparticles have received considerable attention in bioassays and diagnostics due to their unique surface plasmon resonance (SPR) properties. Gold nanoparticles have been employed for the development of SPR-based colorimetric bioassays. In the present report we have described a sensitive colorimetric approach for estimation of proteins, within a detection limit of 10∼80 μg/mL, using unmodified silver nanoparticles. Besides the common advantages of colorimetric assay such as simplicity, high sensitivity, and low cost, our method has a label-free design and provides an important and attractive alternative to classical sensing probes and systems. The present work will contribute to the development of nanotechnology-based diagnostic tools.
Green synthesis and characterization of palladium nanoparticles and its conjugates from solanum trilobatum leaf extract
Authors: Kanchana Amarnath , Devarajan Saveetha , Ayyappan Senniyanallur Rathakrishnan
Published: October 2014

An important area of research in nanotechnology deals with the synthesis of nanoparticles of different chemical compositions, sizes and controlled monodispersity. Currently, there is a growing need to develop environmentally benign nanoparticle synthesis in which no toxic chemicals are used in the synthesis protocol. Palladium nanoparticles (PdNp) are of interest because of their catalytic properties and affinity for hydrogen. Our protocol for the phyto-synthesis of PdNp under moderate pH and room temperature offers a new means to develop environmentally benign nanoparticles. Solanum trilobatum is enlightened in our present study as it is enriched with phytochemicals to reduce palladium chloride ions. Poly MVA a dietary supplement based on the nontoxic chemotherapeutic lipoic acid-palladium complex (LA-Pd) is been hypothesized as the new paradigm of cancer therapy. Hence forth we successfully conjugated lipoic acid (S-PdNp-LA) and vitamins (S-PdNp-Vitamin-LA) to palladium nanoparticles synthesised from Solanum trilobatum leaf extract. These nanoparticles (S-PdNp, S-PdNp-LA, S-PdNp-Vitamin-LA) were characterized with UV-Vis Spectroscopy, SEM and FTIR analysis, which revealed that S-PdNp are polydisperse and of different morphologies ranging from 60∼70 nm (S-PdNp), 65∼80 nm (S-PdNp-LA) and 75∼100 nm (S-PdNp-Vitamin-LA) in size.
Click chemistry approach to functionalize two-dimensional macromolecules of graphene oxide nanosheets
Authors: Kou Liang , He Hongkun , Gao Chao
Published: October 2014

A facile “click chemistry” approach to functionalize 2D macromolecules of graphene oxide nanosheets with poly (ethylene glycol) of different molecular weights, polystyrene, palmitic acid and various amino acids was presented. FTIR, TGA, Raman spectroscopy, XPS, XRD, TEM, AFM and SEM were utilized to characterize the products. High degree of functionalization was achieved on the flat surfaces of graphene oxide, affording polymer-grafted 2D brushes and amino acids-immobilized nanosheets, which show improved solubility in organic solvents. The click chemistry strategy reported herein provides a facile and general method for functionalization of graphene oxide with macromolecules and desired biomolecules.
Functionalization of carbon nanotubes and other nanocarbons by azide chemistry
Authors: Han Jin , Gao Chao
Published: October 2014

Following the conventional carbon allotropes of diamond and graphite, fullerene, carbon nanotubes (CNTs) and graphene as 0D, 1D and 2D graphitic macromolecules have been discovered recently in succession, declaring the unlimited potential of carbon-based nanomaterials and nanotechnology. Although CNTs exhibit significant potential applications in advanced materials and other fields due to their extraordinary mechanical strength and electrical/thermal conductivity properties, their low solubility, poor wettability and bad dispersibility in common solvents and solid matrices have limited their processing and applications. Thus, the attempt to achieve wettable/processable CNTs by functionalization has attracted increasing attention in both scientific and industrial communities. In recent years, azide chemistry has been demonstrated as a powerful means to covalently modify CNTs. It consists of two major approaches: click chemistry and nitrene chemistry, which both involve the usage of various azide compounds. The former one is based on highly reactive and stereospecifical Cu(I) catalyzed azide-alkyne cycloaddition reaction; the latter one is based on the electrophilic attack to unsaturated bonds of CNTs with nitrenes as reactive intermediates formed from thermolysis or photolysis of azides. In this mini-review paper, the azide chemistry to functionalize CNTs is highlighted and the corresponding functionalization routes to build CNT-based complex structures are also discussed. Besides, covalent functionalizations of other graphitic nanomaterials such as fullerence and graphene, via azide chemistry, are commented briefly.
Synthesis and Photocatalytic Activity of One-Dimensional CdS@TiO2 Core-Shell Heterostructures
Authors: Wei Hongwei , Wang Le , Li Zhipeng , Ni Shouqing , Zhao Quanqin
Published: October 2014

One-dimensional CdS@TiO2 core-shell heterostructures were fabricated via the hydrolysis of tetrabutyl titanate (TBT) on preformed CdS nanowires. The as-prepared products were characterized by X-ray diffraction, transmission electron microscopy, selected area electron diffraction and diffuse reflectance spectroscopy techniques. Results demonstrated that the hydrolysis of TBT had a great influence on the morphology of the coated TiO2 shell, resulting in the formation of TiO2 nanoparticles and nanolayer-modified CdS@TiO2 heterostructures. Degradation of methylene blue using CdS@TiO2 core-shell heterostructures as photocatalysts under visible light irradiation was investigated. Comparative photocatalytic tests showed that the TiO2 nanoparticles-modified heterostructure exhibited a superior activity due to the passivity of photogenerated charge carriers.
Hydrothermal Synthesis and Characterization of PEG-Mn3O4 Nanocomposite
Authors: Karaoğlu E. , Deligöz H. , Sözeri H. , Baykal A. , Toprak M. S.
Published: October 2014

Here, we report on the synthesis of PEG-Mn3O4 nanocomposite (NP’s) via a hydrothermal route by using Mn(acac)2, ethanol, NH3 and PEG-400. The crystalline phase was identified as Mn3O4. The crystallite size of the PEG-Mn3O4 nanocomposite was calculated as 12±5 nm from X-ray line profile fitting and the average particle size from TEM was obtained as 200 nm. This reveals polycrystalline character of Mn3O4 NP’s. The interaction between PEG-400 and the Mn3O4 NP’s was investigated by FTIR. Temperature independent AC conductivity of PEG-Mn3O4 nanocomposite beyond 20 kHz provides a strong evidence of ionic conduction through the structure. The conductivity and permittivity measurements strongly depend on the secondary thermal transition of nanocomposite beyond 100°C. Above that temperature, Mn3O4 particles may interact with each other yielding a percolated path that will facilitate the conduction. On the other hand, the relatively lower activation energy (Ea=0.172 eV) for relaxation process suggests that polymer segmental motions of PEG and electrons hopping between Mn2+ and Mn3+ may be coupled in the sample below 100°C. Room temperature magnetization curve of the sample does not reach to a saturation, which indicates the superparamagnetic character of the particles. As the temperature increases, the frequency at which (ε″) reaches a maximum shifted towards higher frequencies. The maximum peak was observed at 1.4 kHz for 20°C while the maximum was detected at 23.2 kHz for 90°C.
Efficient CNTFET-based Ternary Full Adder Cells for Nanoelectronics
Authors: Moaiyeri Mohammad Hossein , Mirzaee Reza Faghih , Navi Keivan , Hashemipour Omid
Published: October 2014

This paper presents two new efficient ternary Full Adder cells for nanoelectronics. These CNTFET-based ternary Full Adders are designed based on the unique characteristics of the CNTFET device, such as the capability of setting the desired threshold voltages by adopting proper diameters for the nanotubes as well as the same carrier mobilities for the N-type and P-type devices. These characteristics of CNTFETs make them very suitable for designing high-performance multiple-V
th structures. The proposed structures reduce the number of the transistors considerably and have very high driving capability. The presented ternary Full Adders are simulated using Synopsys HSPICE with 32 nm CNTFET technology to evaluate their performance and to confirm their correct operation.
Thermodynamic and Kinetic Analysis of Lowtemperature Thermal Reduction of Graphene Oxide
Authors: Yin Kuibo , Li Haitao , Xia Yidong , Bi Hengchang , Sun Jun , Liu Zhiguo , Sun Litao
Published: October 2014

The thermodynamic state and kinetic process of low-temperature deoxygenation reaction of graphene oxide (GO) have been investigated for better understanding on the reduction mechanism by using Differential Scanning Calorimetry (DSC), Thermogravimetry-Mass Spectrometry (TG-MS), and X-ray Photo-electron Spectroscopy (XPS). It is found that the thermal reduction reaction of GO is exothermic with degassing of CO2, CO and H2O. Graphene is thermodynamically more stable than GO. The deoxygenation reaction of GO is kinetically controlled and the activation energy for GO is calculated to be 167kJ/mol (1.73 eV/atom).
High-Performance Li-ion Batteries and Supercapacitors Based on Prospective 1-D Nanomaterials
Authors: Zhao Dandan , Wang Ying , Zhang Yafei
Published: October 2014

One-dimensional (1-D) nanomaterials with superior specific capacity, higher rate capability, better cycling peroperties have demonstrated significant advantages for high-performance Li-ion batteries and supercapacitors. This review describes some recent developments on the rechargeable electrodes by using 1-D nanomaterials (such as LiMn2O4 nanowires, carbon nanofibers, NiMoO4 · nH2O nanorods, V2O5 nanoribbons, carbon nanotubes, etc.). New preparation methods and superior electrochemical properties of the 1-D nanomaterials including carbon nanotube (CNT), some oxides, transition metal compounds and polymers, and their composites are emphatically introduced. The VGCF/LiFePO4/C triaxial nanowire cathodes for Li-ion battery present a positive cycling performance without any degradation in almost theoretical capacity (160 mAh/g). The Si nanowire anodes for Li-ion battery show the highest known theoretical charge capacity (4277 mAh/g), that is about 11 times lager than that of the commercial graphite (∼372 mAh/g). The SWCNT/Ni foam electrodes for supercapacitor display small equivalent series resistance (ESR, 52 mΩ) and impressive high power density (20 kW/kg). The advantages and challenges associated with the application of these materials for energy conversion and storage devices are highlighted.
Effect of Hydrolyzing Agents on the Properties of Poly (Ethylene Glycol)-Fe3O4 Nanocomposite
Authors: Karaoǧlu E. , Kavas H. , Baykal A. , Toprak M. S. , Sözeri H.
Published: October 2014

A PEG assisted hydrothermal route was used to study the influence of the hydrolyzing agent on the properties of PEG-iron oxide (Fe3O4) nanocomposites. Iron oxide nanoparticles (NPs), which confirmed by X-ray diffraction analysis, were successfully synthesized by a hydrothermal method in which NaOH and NH3 were used as hydrolyzing agents. Formation of PEG-Fe3O4 nanocomposite was confirmed by Fourier transform infrared spectroscopy (FTIR). Samples exhibit different crystallite sizes, which estimated based on line profile fitting as 10 nm for NH3 and 8 nm for NaOH hydrolyzed samples. The average particle sizes obtained from transmission electron microscopy was respectively 174±3 nm for NaOH and 165±4 nm for NH3 gas hydrolyzed samples. Magnetic characterization results reveal superparamagnetic characters despite a large particle size, which may indicate the absence of coupling between the nanocrystals due to the polymer in the nanocomposite. The conductivity curve demonstrates that sDC strongly depends on the temperature.
Development of an Amperometric Hydrogen Peroxide Biosensor based on the Immobilization of Horseradish Peroxidase onto Nickel Ferrite Nanoparticle-Chitosan Composite
Authors: Yalçıner Furkan , Çevik Emre , Şenel Mehmet , Baykal Abdülhadi
Published: October 2014

Nickel ferrite (NiFe2O4) nanoparticles have been dispersed in chitosan solution in order to fabricate nanocomposite films. Horseradish peroxidase (HRP) has been immobilized onto this chitosan-NiFe2O4 nanocomposite film via physical adsorption. The size of the NiFe2O4 nanoparticles has been estimated using X-ray diffraction pattern and scanning electron microscopy (SEM) to be 40±9 nm. The chitosan-NiFe2O4 nanocomposite film and HRP/chitosan-NiFe2O4 bioelectrode have been characterized using SEM technique. The HRP/chitosan-NiFe2O4 nanocomposite bioelectrode has a response time of 4 s, linearity as 0.3 to 12mM of H2O2, sensitivity as 22 nA/mM. The effects of pH and the temperature of the immobilized HRP electrode have also been studied.
Fabrication and Optical Properties of Silicon Nanowires Arrays by Electroless Ag-catalyzed Etching
Authors: Tang Jie , Shi Jianwei , Zhou Lili , Ma Zhongquan
Published: October 2014

In order to realize ultralow surface reflectance and broadband antireflection effects which common pyramidal textures and antireflection coatings can’t achieve in photovoltaic industry, we used low-cost and easy-made Ag-catalyzed etching techniques to synthesize silicon nanowires (SiNWs) arrays on the substrate of single-crystalline silicon. The dense vertically-aligned Si NWs arrays are fabricated by local oxidation and selective dissolution of Si in etching solution containing Ag catalyst. The Si NWs arrays with 3 μm in depth make reflectance reduce to less than 3% in the range of 400 to 1000 nm while reflectance gradually reached the optimum value with the increasing of etching time. The antireflection of Si NWs arrays are based on index-graded mechanism: Si NWs arrays on a subwavelength scale strongly scatter incident light and have graded refractive index that enhance the incidence of light in usable wavelength range. However, surface recombination of Si NWs arrays are deteriorated due to numerous dangling bonds and residual Ag particles.
Alignment of Nanoscale Single-Walled Carbon Nanotubes Strands
Authors: Yang Danna , Wang Lin , Zhang Xiaoxian , Wang Dongwei , Shen Zhiqiang , Li Sai
Published: October 2014

Depositing single-walled carbon nanotubes (SWNTs) with controllable density, pattern and orientation on electrodes presents a challenge in today’s research. Here, we report a novel solvent evaporation method to align SWNTs in patterns havingnanoscale width and micronscale length. SWNTs suspension has been introduced dropwise onto photoresist resin microchannels; and the capillary force can stretch and align SWNTs into strands with nanoscale width in the microchannels. Then these narrow and long aligned SWNTs patterns were successfully transferred to a pair of gold electrodes with different gaps to fabricate carbon nanotube field-effect transistor (CNTFET). Moreover, the electrical performance of the CNTFET show that the SWNTs strands can bridge different gaps and fabricate good electrical performance CNTFET with ON/OFF ratio around 106. This result suggests a promising and simple strategy for assembling well-aligned SWNTs into CNTFET device with good electrical performance.
Comparative Performance Evaluation of Large FPGAs with CNFET- and CMOS-based Switches in Nanoscale
Authors: Moaiyeri Mohammad Hossein , Jahaniana Ali , Navia Keivan
Published: October 2014

Routing resources are the major bottlenecks in improving the performance and power consumption of the current FPGAs. Recently reported researches have shown that carbon nanotube field effect transistors (CNFETs) have considerable potentials for improving the delay and power consumption of the modern FPGAs. In this paper, hybrid CNFET-CMOS architecture is presented for FPGAs and then this architecture is evaluated to be used in modern FPGAs. In addition, we have designed and parameterized the CNFET-based FPGA switches and calibrated them for being utilized in FPGAs at 45 nm, 22 nm and 16 nm technology nodes. Simulation results show that the CNFET-based FPGA switches improve the current FPGAs in terms of performance, power consumption and immunity to process and temperature variations. Simulation results and analyses also demonstrate that the performance of the FPGAs is improved about 30%, on average and the average and leakage power consumptions are reduced more than 6% and 98% respectively when the CNFET switches are used instead of MOSFET FPGA switches. Moreover, this technique leads to more than 20.31% smaller area. It is worth mentioning that the advantages of CNFET-based FPGAs are more considerable when the size of FPGAs grows and also when the technology node becomes smaller.
Dye-sensitized Solar Cells with Higher Jsc by Using Polyvinylidene Fluoride Membrane Counter Electrodes
Authors: Li Xiaodong , Zhang Dingwen , Chen Si , Zhang Heng , Sun Zhuo , Huang Sumei , Yin Xijiang
Published: October 2014

A flexible counter electrode (CE) for dye-sensitized solar cells (DSCs) has been fabricated using a micro-porous polyvinylidene fluoride membrane as support media and sputtered Pt as the catalytic material. Non-conventional structure DSCs have been developed by the fabricated CEs. The Pt metal was sputtered onto one surface of the membrane as the catalytic material. DSCs were assembled by attaching the TiO2 electrode to the membrane surface without Pt coating. The membrane was with cylindrical pore geometry. It served not only as a substrate for the CE but also as a spacer for the DSC. The fabricated DSC with the flexible membrane CE showed higher photocurrent density than the conventional sandwich devices based on chemically deposited Pt/FTO glass, achieving a photovoltaic conversion efficiency of 4.43%. The results provides useful information in investigation and development of stable, low-cost, simple-design, flexible and lightweight DSCs.
III-Nitride-Based Quantum Dots and Their Optoelectronic Applications
Authors: Weng G. E. , Ling A. K. , Lv X. Q. , Zhang J. Y. , Zhang B. P.
Published: October 2014

During the last two decades, III-nitride-based quantum dots (QDs) have attracted great attentions for optoelectronic applications due to their unique electronic properties. In this paper, we first present an overview on the techniques of fabrication for III-nitride-based QDs. Then various optoelectronic devices such as QD lasers, QD light-emitting diodes (LEDs), QD infrared photodetectors (QDIPs) and QD intermediate band (QDIB) solar cells (SCs) are discussed. Finally, we focus on the future research directions and how the challenges can be overcome.
Synthesis of Micron-sized Hexagonal and Flower-like Nanostructures of Lead Oxide (PbO2) by Anodic Oxidation of Lead
Authors: Singh Dinesh Pratap , Srivastava Onkar Nath
Published: October 2014

Micron sized hexagon- and flower-like nanostructures of lead oxide (α-PbO2) have been synthesized by very simple and cost effective route of anodic oxidation of lead sheet. These structures were easily obtained by the simple variation of applied voltage from 2–6 V between the electrodes. Lead sheet was used as an anode and platinum sheet served as a cathode. Anodic oxidation at 2 V resulted in the variable edge sized (1–2 μm) hexagon-like structures in the electrolyte. When the applied potential was increased to 4 V a structure of distorted hexagons consisting of some flower-like structures were obtained. Further increment of potential up to 6 V resulted in flower like structures of α-PbO2 having six petals. The diameter of the flower-like structures was ∼200–500 nm and the size of a petal was ∼100–200 nm.
Mixed Phase Anatase/rutile Titanium Dioxide Nanotubes for Enhanced Photocatalytic Degradation of Methylene-blue
Authors: Boehme Mario , Ensinger Wolfgang
Published: October 2014

Titanium dioxide Nanotubes (TNTs) prepared by electroless deposition have been annealed at air ambient and low temperature. As a result, the anatase/rutile phase composition of the TNTs can be tailored to the needs of later applications. Nanotubes with anatase/rutile mixed phase ratio of 4:1 have been produced in this report and further examined for their photocatalytical behavior. The photocatalytical properties of the TNTs have been observed by degradation of methylene-blue in aqueous solution under low power UV-light irradiation. The results shown in this report are based on the synergetic effect between rutile and anatase, which results in the mixed phase TiO2 nanotubes having enhanced photocatalytical properties.
Research on the Forming Mechanism of Micro/Nano Features during the Cast Molding Process
Authors: Ye Xiangdong , Duan Yugang , Ding Yucheng
Published: October 2014

Cast molding process has provided a reliable, simple and cost-effective way to fabricate micro structures since decades ago. In order to obtain structures with fine, dense and deep nano-size features by cast molding, it is necessary to study the forming mechanism in the process. In this paper, based on major steps of cast molding, filling models of liquid are established and solved; and the forming mechanism of liquid is revealed. Moreover, the scale effect between the liquid and the cavity on the filling velocity of liquid is studied. It is also interesting to find out that the wettability of liquid on the cavity may be changed from wetting to dewetting depends on the pressure difference. Finally, we experimentally verify some of our modeling results on the flowing and filling state of the liquid during the cast molding process.
Magnetic Tunnel Junction Based on MgO Barrier Prepared by Natural Oxidation and Direct Sputtering Deposition
Authors: Chen Xiaohong , Freitas Paulo P.
Published: October 2014

Magnetic tunnel junctions (MTJs) based on MgO barrier have been fabricated by sputtering single crystal MgO target and metal Mg target, respectively, using magnetic sputtering system Nordiko 2000. MgO barriers have been formed by a multi-step deposition and natural oxidization of Mg layer. Mg layer thickness, oxygen flow rate and oxidization time were adjusted and the tunnel magnetoresistance (TMR) ratio of optimal MTJs is over 60% at annealing temperature 385°. The (001) MgO crystal structure was obtained when the separation distance between MgO target and substrate is less than 6 cm. The TMR ratio of most MgO based MTJs are over 100% at the separation distance of 5 cm and annealing temperature 340°C. The TMR ratios of MTJs are almost zero when the separation distance ranges from 6 to 10 cm, due to the amorphous nature of the MgO film.
The Assembly of C60 in Semicrystalline PLLA Matrix
Authors: Chen Li , Pang Xiujiang
Published: October 2014

It has increasingly become a research focus to build higher structure composed of C60. However, there has been very few reports on the influence of polymer addition on the self-assembling behavior of fullerene in organic solvents. In this research, big needle-like C60 assemblings have been obtained in the form of PLLA/C60 composites. The largest C60 needles can be observed by naked eyes. The amount of C60 in the composite influences the length of C60 needles to some extent. DSC results indicate C60 accelerates the crystallization and lift the relative crystallinity of PLLA matrix. the results also imply the addition of semicrystalline PLLA influence the assembling behavior of C60. i.e., the crystallization of PLLA accelerated by C60 also act a driving force for the enriching and the linear assembling of C60 in PLLA matrix via Van der Waals force.
Effect of Biosynthesized Silver Nanoparticles on Staphylococcus aureus Biofilm Quenching and Prevention of Biofilm Formation
Authors: Chaudhari Pratik R. , Masurkar Shalaka A. , Shidore Vrishali B. , Kamble Suresh P.
Published: October 2014

The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. The synthesis of silver nanoparticles was achieved using Bacillus cereus supernatant and 1 mM silver nitrate. 100 mM glucose was found to quicken the rate of reaction of silver nanoparticles synthesis. UV-visible spectrophotometric analysis was carried out to assess the synthesis of silver nanoparticles. The synthesized silver nanoparticles were further characterized by using Nanoparticle Tracking Analyzer (NTA), Transmission Electron Microscope and Energy Dispersive X-ray spectra. These silver nanoparticles showed enhanced quorum quenching activity against Staphylococcus aureus biofilm and prevention of biofilm formation which can be seen under inverted microscope (40 X). The synergistic effect of silver nanoparticles along with antibiotics in biofilm quenching was found to be effective. In the near future, silver nanoparticles could be used in the treatment of infections caused by highly antibiotic resistant biofilm.
High Potential Columnar Nanocrystalline AlN Films Deposited by RF Reactive Magnetron Sputtering
Authors: Han Chengzhang , Chen Da , Zhang Yaozhong , Xu Dong , Liu Yijian , Kong Eric Siu-Wai , Zhang Yafei
Published: October 2014

Columnar nanocrystalline aluminum nitride (cnc-AlN) thin films with (002) orientation and uniform texture have been deposited successfully on large silicon wafers by RF reactive magnetron sputtering. At the optimum sputtering parameters, the deposited cnc-AlN thin films show a c-axis preferred orientation with a crystallite size of about 28 nm and surface roughness (RMS) of about 1.29 nm. The cnc-AlN thin films were well transparent with an optical band gap about 4.8 eV, and the residual compressive stress and the defect density in the film have been revealed by Ramon spectroscopy. Moreover, piezoelectric performances of the cnc-AlN thin films executed effectively in a film bulk acoustic resonator structure.
Synthesis of Cobalt Chromite Nanoparticles by Thermolysis of Mixed Cr3+ and Co2+ Chelates of 2-Mercaptopyridin N-Oxide
Authors: Edrissi Mohammad. , Keshavarz Ahmad Reza
Published: October 2014

Pure greenish-blue cobalt chromite (CoCr2O4) nanoparticles with narrow particle range of 4.1±1.9 nm and surface area of 78.2 m2g−1 were synthesized through mixed chelates thermolysis of corresponding metals using 2-Mercaptopyridine N-oxide sodium salt as chelating agent. During the thermolysis procedure, high amount of gases were emitted that led to the formation of nanoparticles with high surface area. The product was characterized by TGA, DTG, XRD, TEM, SEM, LLS, BET and chemical analysis. Design of experiments was performed to fulfill the two levels L4 Taguchi design. It was found that the temperature and time of thermolysis process have significant effect on the particle size reduction. The Oxidation of trichloroethylene was carried out over CoCr2O4 nanocrystallite. Catalytic activity analysis revealed that the synthesis CoCr2O4 possesses high catalytic activity for this process.
Preparation and Characterization of Freestanding Hierarchical Porous TiO2 Monolith Modified with Graphene Oxide
Authors: Wan Lei , Long Mingce , Zhou Dongying , Zhang Liying , Cai Weimin
Published: October 2014

Catalyst recovery is one of the most important aspects that restrict the application of TiO2 photocatalyst. In order to reduce restrictions and improve the photocatalytic efficiency, a hierarchical porous TiO2 monolith (PTM) with well-defined macroporous and homogeneous mesoporous structure was prepared by using a sol-gel phase separation method. P123 was used as the mesoporous template and graphene oxide was applied to increase the activity and integrity of the monolithic TiO2. According to scanning electron microscopy and the Barrett-Joyner-Halenda measurements, PTM3 is mainly composed of 10 nm anatase crystallines with 3.6 nm mesopores and 2–8 μm macropores. Further characterization suggests carbon and nitrogen have been maintained in the PTM during calcinations so as to induce the visible light activity. The PTM with 0.07 wt% graphene oxide dosage shows high efficiency for methyl orange (MO) decolorization under both full spectrum and visible light irradiation (λ>400 nm). Besides, the monolith remains intact and has good photocatalytic stability after four cyclic experiments.
Type-II Core/Shell Nanowire Heterostructures and Their Photovoltaic Applications
Authors: Cao Yiyan , Wu Zhiming , Ni Jianchao , Bhutto Waseem. A. , Li Jing , Li Shuping , Huang Kai , Kang Junyong
Published: October 2014

Nanowire-based photovoltaic devices have the advantages over planar devices in light absorption and charge transport and collection. Recently, a new strategy relying on type-II band alignment has been proposed to facilitate efficient charge separation in core/shell nanowire solar cells. This paper reviews the type-II heterojunction solar cells based on core/shell nanowire arrays, and specifically focuses on the progress of theoretical design and fabrication of type-II ZnO/ZnSe core/shell nanowire-based solar cells. A strong photoresponse associated with the type-II interfacial transition exhibits a threshold of 1.6 eV, which demonstrates the feasibility and great potential for exploring all-inorganic versions of type-II heterojunction solar cells using wide bandgap semiconductors. Future prospects in this area are also outlooked.
Recent Advances in Directed Assembly of Nanowires or Nanotubes
Authors: Liu Mei , Wu Zhizheng , Lau Woon Ming , Yang Jun
Published: October 2014

Nanowires and nanotubes of diverse material compositions, properties and/or functions have been produced or fabricated through various bottom-up or top-down approaches. These nanowires or nanotubes have also been utilized as potential building blocks for functional nanodevices. The key for the integration of those nanowire or nanotube based devices is to assemble these one dimensional nanomaterials to specific locations using techniques that are highly controllable and scalable. Ideally such techniques should enable assembly of highly uniform nanowire/nanotube arrays with precise control of density, location, dimension or even material type of nanowire/nanotube. Numerous assembly techniques are being developed that can quickly align and assemble large quantities of one type or multiple types of nanowires through parallel processes, including flow-assisted alignment, Langmuir-Blodgett assembly, bubble-blown technique, electric/magnetic- field directed assembly, contact/roll printing, knocking-down, etc.. With these assembling techniques, applications of nanowire/nanotube based devices such as flexible electronics and sensors have been demonstrated. This paper delivers an overall review of directed nanowire assembling approaches and analyzes advantages and limitations of each method. The future research directions have also been discussed.
Self-Assembled Monolayer of Mixed Gold and Nickel Nanoparticles
Authors: Jie Yanni , Fan Huiqing , You Wei
Published: October 2014

Forming a monolayer of mixed nickel and gold nanoparticles through self-assembly via simple solution processing constitutes an important step toward inexpensive nanoparticle-based carbon nanofiber growth. In this work, mixed gold and nickel nanoparticles were anchored on the silicon wafer using self-assembled monolayers (SAMs) as a template. SAMs of 3-mercaptopropyl trimethoxysilane (MPTS-SAMs) were formed on silicon wafer, with the exposed thiol functionality providing ligand exchange sites to form the mixed monolayer of nickel and gold nanoparticles via a two-step sequential soaking approach. The densities of the nickel and gold nanoparticles on the surface can be varied by adjusting the soaking sequence.
Fabrication and Microwave Absorption Properties of Fe0.64Ni0.36-NiFe2O4 Nanocomposite
Authors: Yan Xu , Xue Desheng
Published: October 2014

Fe0.64Ni0.36−NiFe2O4 nanocomposite was performed with partially reducing NiFe2O4 nanoparticles in Ar/H2 ambient. The microwave and static magnetic properties were investigated. The results showed that the nanocomposite was characterized with enhanced microwave absorption properties. The optimal reflection loss (RL) of the nanocomposite reached −24.8 dB at 14 GHz for an absorber thickness of 1.5 mm. Meanwhile, a broad bandwidth for RL<-10 dB was obtained in the range of 3.1–15.1 GHz for an absorber thickness from 1.0 to 4.0 mm. The enhancement is attributed to the increase of dielectric and magnetic loss after reducing procedure.
Characterization of Cysteine Coated Magnetite Nanoparticles as MRI Contrast Agent
Authors: Ahmadi Reza , Gu Ning , Madaah Hosseini Hamid Reza
Published: October 2014

In this work, a kind of stabilized ferrofluid based on magnetite nanoparticles (mean core and its coating size about 21.9 and 1.6 nm, respectively) was synthesized via coprecipitation method. Cysteine was used as surfactant due to its proper conjunction to the surface of magnetite nanoparticles. Coating density and synthesized ferrofluids were characterized by using transmission electron microscope, thermogravimetry analysis, dynamic light scattering and fourier transform infrared spectroscopy techniques. Magnetic resonance imaging studies show that the synthesized ferrofluid can be used as a potential contrast enhancement agent especially for imaging lymphatic system.
YbF3/SiO2 Fillers as Radiopacifiers in a Dental Adhesive Resin
Authors: Carreño Neftali L. V. , Oliveira Thiago C. S. , Piva Evandro , Leal Fernanda B. , Lima Giana S. , Moncks Marcelo D. , Raubach Cristiane W. , Ogliari Fabrício A.
Published: October 2014

The objective of this study was to evaluate the effect of functionalizing a dental adhesive resin with YbF3/SiO2 fillers for use as radiopacifiers. Particles of YbF3/SiO2 were obtained with the high-energy mechanical milling method and characterized by both physical and chemical methods. After characterization, the particles were sieved and silanized prior to being incorporated into an adhesive resin. The stability of the particle suspension was then evaluated. After light activation, the radiopacity, degree of conversion, flexural strength and elastic modulus were determined. The dental adhesive resins with 10 and 15 wt% of filler provided satisfactory radiopacity, while flexural strength and elastic modulus were not affected. The degree of conversion was statistically lower than that of the control (p<0.05). The method used for incorporating the tested ytterbium fluoride/silicon dioxide particles at concentrations of 10 and 15 wt% was shown to be feasible for the development of a radiopaque dental adhesive system.
Enhanced Current Transportation in Siliconriched Nitride (SRN)/Silicon-riched Oxide (SRO) Multilayer Nanostructure
Authors: Tao Yeliao , Zheng Jun , Zuo Yuhua , Xue Chunlai , Cheng Buwen , Wang Qiming
Published: October 2014

A novel structure of silicon-riched nitride (SRN)/silicon-riched oxide (SRO) is proposed and prepared using RF reactive magnetron co-sputtering. High temperature annealing of SRN/SRO multilayers leads to formation of Si nanocrystals (NC) from isolating SRN and SRO layers simultaneously, which efficiently improves carrier transport ability compared to conventional SRN/Si3N4 counterpart. Micro-Raman scattering analysis reveals that SRN layer has dominating number of denser and smaller Si NCs, while SRO layer has relatively less, sparser and bigger Si NCs, as confirmed by high resolution transmission electron microscopy observation. The substitute SRO layers for Si3N4 counterparts significantly increase the amount of Si NCs as well as crystallization ratio in SRN layers; while the average Si NC size can be well controlled by the thickness of SRN layers and the content of N, and hence an obvious stronger absorption in UV region for the novel structure can be observed in absorption spectra. The I–V characteristics show that the current of hybrid SRN/SRO system increases up to 2 orders of magnitude at 1 V and even 5 orders of magnitude at 4 V compared to that of SRN/Si3N4 structure. Si NCs in SiOy layers provide a transport pathway for adjacent Si NCs in SiNx layers. The obvious advantage in carrier transportation suggests that SRN/SRO hybrid system could be a promising structure and platform to build Si nanostructured solar cells.
Contact Mechanism of the Ag-doped Trimolybdate Nanowire as An Antimicrobial Agent
Authors: Jiang Yujie , Gang Jian , Xu Sheng-Yong
Published: October 2014

Antibacterial Ag-agents are intensively applied as broad spectrum, high-stability, high-efficiency and high-safety inorganic antibacterial agents. We have developed a new kind of antibacterial Ag-agent, namely Ag2−x
(NH4)
x
Mo3O10·3H2O nanowires (NWs). Carrying Ag atoms in the lattice and Ag-rich nanoparticles on the surface, the Ag-doped NWs show strong antibacterial effects for a variety of bacteria including E. coli, Staphylococcus aureus, Candida albicans and Aspergillus niger. By performing systematic comparison experiments, we have proven that the main antibacterial effects are neither resulted from the tiny amount of Ag+ ions released from the Ag-doped NWs in aqueous solutions, nor resulted from Ag-rich nanoparticles of fragments of the NWs when they are slowly dissolved in the Martin broth. Instead, the effects are mainly resulted from a contact mechanism, under which, the Ag-doped NWs need to be physically in contact with the bacteria to be eliminated. This is a novel phenomenon observed in the interactions between nanomaterials and live cells, which is worthy of further investigation at the molecular scale. As the Ag-doped NWs are not dissolved in pure water or weak acids, one may find practical antibacterial applications in textile industry and food storage industry for these unique nanomaterials.
Titania Nanostructures for Dye-sensitized Solar Cells
Authors: Byranvand M. Malekshahi , Kharat A. Nemati , Bazargan M. H.
Published: October 2014

Titania is one kind of important materials, which has been extensively investigated because of its unique electronic and optical properties. Research efforts have largely focused on the optimization of the dye, but recently the titania nanostructures electrode itself has attracted more attention. It has been shown that particle size, shape, crystallinity, surface morphology, and chemistry of the TiO2 material are key parameters which should be controlled for optimized performance of the solar cell. Titania can be found in different shape of nanostructures including mesoporous, nanotube, nanowire, and nanorod structures. The present article reviews the structural, synthesis, electronic, and optical properties of TiO2 nanostructures for dye sensitized solar cells.
Fabrication of Anti-reflecting Si Nano-structures with Low Aspect Ratio by Nano-sphere Lithography Technique
Authors: Sun Shenghua , Lu Peng , Xu Jun , Xu Ling , Chen Kunji , Wang Qimin , Zuo Yuhua
Published: October 2014

Nano-structured photon management is currently an interesting topic since it can enhance the optical absorption and reduce the surface reflection which will improve the performance of many kinds of optoelectronic devices, such as Si-based solar cells and light emitting diodes. Here, we report the fabrication of periodically nano-patterned Si structures by using polystyrene nano-sphere lithography technique. By changing the diameter of nano-spheres and the dry etching parameters, such as etching time and etching power, the morphologies of formed Si nano-structures can be well controlled as revealed by atomic force microscopy. A good broadband antireflection property has been achieved for the formed periodically nano-patterned Si structures though they have the low aspect ratio (<0.53). The reflection can be significantly reduced compared with that of flat Si substrate in a wavelength range from 400 nm to 1200 nm. The weighted mean reflection under the AM1.5 solar spectrum irradiation can be as low as 3.92% and the corresponding optical absorption is significantly improved, which indicates that the present Si periodic nano-structures can be used in Si-based thin film solar cells.
Acetylcholinesterase Biosensor Based on Poly (diallyldimethylammonium chloride)-multi-walled Carbon Nanotubes-graphene Hybrid Film
Authors: Sun Xia , Gong Zhili , Cao Yaoyao , Wang Xiangyou
Published: October 2014

In this paper, an amperometric acetylcholinesterase (AChE) biosensor for quantitative determination of carbaryl was developed. Firstly, the poly (diallyldimethy-lammonium chloride) -multi-walled carbon nanotubes-graphene hybrid film was modified onto the glassy carbon electrode (GCE) surface, then AChE was immobilized onto the modified GCE to fabricate the AChE biosensor. The morphologies and electrochemistry properties of the prepared AChE biosensor were investigated by using scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. All variables involved in the preparation process and analytical performance of the biosensor were optimized. Based on the inhibition of pesticides on the AChE activity, using carbaryl as model compounds, the biosensor exhibited low detection limit, good reproducibility and high stability in a wide range. Moreover, the biosensor can also be used for direct analysis of practical samples, which would provide a new promising tool for pesticide residues analysis.