bluuebunny/crossref_metadata_2025_split huggingface dataset:
PVA(Polyvincyl Acohol)-assisted Hydrothermal Preparation of Bi25FeO40 and Its Photocatalytic Activity
Authors: Jianmin Li , Song Juyue , Chen Jianguo , Yu Shengwen , Jin Dengren , Cheng Jinrong 
Published: January 2010

AbstractA PVA-assisted hydrothermal synthesis route was utilized to fabricate single-phase Bi25FeO40 crystallites.X-ray diffraction results indicated that sillenite Bi25FeO40 have been synthesized at the temperature of 200 ℃ using the KOH concentration of 7 M. Scanning electron microscopy showed the morphology of the as-prepared products were cubic shape with side length of 26μm. The band gap of Bi25FeO40 was determined to be 1.8 eV (688 nm) by using UV-vis diffuse reflectance spectroscopy. It was found that Bi25FeO40 exhibited a high photocatalytic activity for the degradation of methyl orange under UV-Vis irradiation, being a potential material for photocatalytic decomposition of organic contaminants.
Nitrogen-Doping Induced Optical Bandgap Widening of P-Type Cu2O Flms
Authors: Nakano Yoshitaka , Saeki Shu , Morikawa Takeshi 
Published: January 2010

AbstractWe have investigated the effect of N doping into Cu2O films deposited by reactive magnetron sputtering. With increasing N-doping concentration up to 3 at.%, the optical bandgap energy is enlarged from ˜2.1 to ˜2.5 eV with retaining p-type conductivity as determined by optical absorption and Hall-effect measurements. Additionally, photoelectron spectroscopy in air measurements shows an increase in the valence and conduction band shifts with N doping. These experimental results demonstrate possible optical bandgap widening of p-type N-doped Cu2O films, which is a phenomenon that is probably associated with significant structural changes induced by N doping, as suggested from x-ray diffraction measurements.
Assembly and Interfacial Effects in Hybrid Nanostructures of Zinc Oxide and Gold
Authors: Ito Daisuke , McKenzie Lallie C , Masuko Keiichiro , Hutchison James E 
Published: January 2010

AbstractGold nanoparticles were linked to ZnO films and nanowires using phosphonic and carboxylic acid ligands. TEM and STEM-HAADF characterization showed that gold nanoparticles modified with both types of ligands anchored on ZnO nanowire surfaces as well as on ZnO films. After removing the ligands from the interface between ZnO nanowires and supported gold nanoparticles, the electric conductivity in the presence of methanol vapor increased by 100 times as compared to the bare ZnO nanowire, which suggested enhanced-catalytic effects due to the hybrid structure. In addition, ZnO/Au nanomaterials were synthesized by linking ZnO nanoparticles and carboxylate-functionalized gold nanoparticles in solution. UV-vis characterization showed both the bandgap absorption from ZnO and the plasmon absorption from gold nanoparticles. Formation of hybrid nanosystems like these using organic ligands as linkers not only can lead to materials with enhanced properties but also minimize the waste of precious elements because the assembly process is an additive, rather than subtractive, process.
Photocatalytic activity of ZnO nanostructured film grown by activated reactive
Authors: Dhayalan Yuvaraj , k narasimha rao 
Published: January 2010

AbstractZnO nanostructured films were deposited at room temperature on glass substrates and cotton fabrics by activated reactive evaporation in a single step without using metal catalyst or templates. Morphological observation has shown that the nanostructured film contains seaurchin-like structures, and this seaurchin containing large number of randomly grown ZnO nanoneedles. Microstructural analysis revealed the single crystalline nature of the grown nanoneedles and their growth direction was indentified to be along [0002]. PL spectrum of nanostructured films has shown a relatively weak near-band-edge emission peak at 380 nm, and a significant broad peak at 557 nm due to the oxygen vacancy-related emission. ZnO nanostructured films grown on glass substrates and cotton fabrics have shown good photocatalytic activity against rhodamine B.
Characterization of Pore Framework Structure in Monolithic Mesoporous Silica
Authors: Wu Ching-Mao , Lin Szu-Yin , Weng Chin-Cheng , Huang Kuo-Tung 
Published: January 2010

AbstractMesoporous silica materials have received much interest due to commercial applications in chemical separations and heterogeneous catalysis. Recent studies have reported via a sol-gel nanocasting technique, monolithic mesoporous silica with wormlike pore framework could be prepared by utilizing room-temperature ionic liquids (RTILs) as templates and solvents. Although previous reports have indicated that the wormlike pores would be formed in the silica, the detailed pore network structure still remained the crucial issues to be resolved. In the present study, we investigated the pore structure in the monolithic mesoporous silica, which was templated by RTIL (1-butyl-3-methyl-imidazolium-tetrafluoroborate). We revealed an open fractal pore network with a branched and self-similar appearance was formed by the aggregation of the individual spherical pores. Transmission electron microscopy micrographs displayed that the disordered wormlike pore framework was formed in the silica. Furthermore, the small angle X-ray scattering profile measured herein further exhibited three distinct regions of power-law scattering on the respective length scales. In the high-q region, the profile followed Power behavior and a power-law of -4 was observed for the surface fractal dimension of 2, manifesting the primary pore with a smooth surface and a spherical appearance. In the intermediate-q region, a power-law of -2.5 (mass fractal dimension of 2.5), indicating an open mass fractal network was formed by the aggregation of the individual primary pores. Moreover in the low-q region, the power-law of -4 was observed for mass-fractal agglomerates of aggregates. With the proceeding analysis of unified equation in terms of two structural levels, the radiuses of gyration of primary pore (Rg1)and its aggregates (Rg2) were fitted as ca. 0.9 nm and 5.5 nm, respectively. For a spherical-model pore, the radius of pore (R) was ca. 1.16 nm; thus, the averaged pore diameter (D) was 2.32 nm. The number of primary pores in a fractal aggregate (degree of aggregation, z) was calculated as ca. 67.
Morphological Instability of Metallic Surfaces: Adsorbate Induced Nanoscale Faceting
Authors: Gupta Govind , Baier Robert , Chen Wenhua , Wang Hao , Madey Theodore E 
Published: January 2010

AbstractHeterogeneous catalysis is a field of major interest in the surface science and development of new supported model catalysts with a narrow size distribution. The possibility to create narrow size distributions is to use the faceted surface structures as self assembled templates on which metal nanoclusters can grow. In the present study, new aspects of adsorbate induced faceting and nanoscale phenomena on adsorbate-covered metallic surfaces are studied on atomically-rough morphologically unstable metallic fcc (Rh) and hcp (Re) surfaces. Formation of oxygen induced faceting of atomically-rough Rh (210) surface has been studied and characterized by means of LEED, STM and AES. The LEED studies confirm the formation of three sided faceted (nanoscale pyramidal structure) Rh(210) surface when the oxygen covered Rh surface annealed to temperature higher than 550K. The facet orientations of the nanopyramid are characterized as two {731} face and a reconstructed (110) face. The excess oxygen overlayer can be removed from pyramidal faceted Rh(210) surface via catalytic reaction at low temperature using CO oxidation or H2 reaction while preserving the pyramidal structure. The average size of the nanopyramids is observed to be dependent on annealing temperature and vary from 12nm to 21nm. The atomically resolved STM images confirm the LEED observations and also revealed that (110) face of nanopyramids exhibits various reconstructions (1×n, n = 2-4) depending on oxygen coverage. Further, oxygen induced nanoscale faceted Re (12-31) surface has been formed which consist of nano-trenches (two sided ridges) with facets in (11-21) and (01-10) direction. These two- sided faceted Re (12-31) surface is used as a template to grow gold nanostructures. Under controlled growth conditions, the gold induced nanostructures are formed on oxygen induced nano-trenched Re (12-31) surface. It is observed that gold grows in the form of islands on the faceted rhenium substrate i.e. at lower coverages (≥0.8ML), it forms 2D islands whereby for higher coverages 3D islands are formed on top of the nano-ridges. The surfaces morphology of the gold covered faceted Re surface changes drastically on annealing, for the temperature >870 K, gold atoms wet the rhenium template while annealing to higher temperature (˜970K) led to the development of a three sided nanopyramids. On further annealing to higher temperatures (>1100K) cause the complete destruction of the faceted structure. LEED and STM studies revealed that the gold induced three sided nanopyramids consists of two faces of original two sided ridges with (11-20), (01-10) orientation and an additional facet in (12-32) direction. The high resolution STM images revealed that the (12-32) facet of the nanopyramid is fully decorated with single atomic zigzag gold nanochain. These faceted surfaces can be potential template for heterogeneous catalysis and development of new supported model catalysts with a narrow size distribution.
Water-soluble Poly(4-styrenesulfonic acid-co-maleic acid)-stabilized Nickel(0) and Cobalt(0) Nanoclusters as Highly Active Catalysts in Hydrogen Generation from the Hydrolysis of Ammonia-Borane
Authors: Metin Önder , Özkar Saim 
Published: January 2010

AbstractWater soluble poly(4-styrenesulfonic acid-co-maleic acid), PSSA-co-MA, stabilized nickel(0) and cobalt(0) nanoclusters were prepared for the first time from the reduction of nickel(II) chloride and cobalt(II) chloride by using minimum amount of sodium borohydride shortly before their usage as catalysts in the hydrolysis of ammonia-borane (AB) in the same medium at room temperature. PSSA-co-MA stabilized nickel(0) and cobalt(0) nanoclusters showed high catalytic activity in hydrogen generation from the hydrolysis of AB even at low temperature.
Greener Synthesis of Nanoparticles Using Fine Tuned Hydrothermal Routes
Authors: Han Hyunjoo , Francesco Gianna Di , Sexton Amber , Tretiak Andrew , Maye Mathew M. 
Published: January 2010

AbstractThe wet chemical synthesis of energy and sensor relevant nanomaterials often requires large amounts of high boiling point solvents, grams of reactants, solvent-based purification, and the use of oxygen free atmospheres. These synthetic routes are also prone to poor scalability due to requirements of precise control of high temperatures. Because of this, the potential use of metallic nanoparticles and semiconductive quantum dots (q-dots) in energy transfer and real time biosensor applications is labor intensive and expensive. We have explored a green alternative route that involves the colloidal synthesis of CdSe and CdTe quantum dots under well-controlled hydrothermal conditions (100-200°C) using simple inorganic precursors. The resulting nanomaterials are of high quality, and are easily processed depending upon application, and their synthesis is scalable. Temperature control, and synthetic scalability is provided by the use of a synthetic microwave reactor, which employs computer-controlled dielectric heating for the rapid and controllable heating.
Mist Deposition Technique as a Green Chemical Route for Synthesizing Oxide and Organic Thin Films
Authors: Fujita Shizuo , Kaneko Kentaro , Fukui Yutaka , Nishinaka Hiroyuki , Ikenoue Takumi , Nomura Taichi 
Published: January 2010

AbstractUltrasonic spray-assisted mist deposition techniques have been developed as a cost-effective and environmental friendly deposition method for oxide and organic thin films. The chemical vapor deposition (CVD) of a variety of oxide thin films having unique functions, such as Cr2O3, Cu2O, Fe3O4, and Al2O3 thin films, has been demonstrated as well as high-quality ZnO and Ga2O3 films ever reported. In addition to the films deposition by the CVD process, the deposition of organic material thin films from the source solution has also been achieved; as examples we have shown the patterned deposition of water-soluble fluorescent polymers with a metal mask. This may substitute the spin-coating technique and contribute to increase the source consumption efficiency in the thin film deposition. We appeal that the mist deposition is a unique and promising technique as a green chemical route for film deposition.
MS2 Bacteriophage as a Biotemplate for Semiconductor Nanoparticle Synthesis
Authors: Cohen Brian A. , Kaloyeros Alain E. , Bergkvist Magnus 
Published: January 2010

AbstractIn this work, we demonstrate the synthesis of cadmium sulfide (CdS) nanoparticles in aqueous solution with MS2 bacteriophages as a biotemplate. Bionanofabrication methods offer unique opportunities for nanomaterials synthesis, where choice of biotemplate can influence the size, shape and function of the produced material. Synthesis reactions are carried out under mild aqueous conditions, and thus hazardous organic solvents, high temperature, and extreme pH can be avoided. The MS2 bacteriophage is a potential template system for bionanofabrication of nanoscale materials due to its size and inherent physical/chemical properties. MS2 capsid proteins can be genetically modified to incorporate functional groups and sequences. Also, genomic RNA in MS2 can be degraded or replaced with other oligonucleotide sequences and still form intact capsids. In this work, we use MS2 for bio-assisted synthesis of CdS nanoparticles and adjust the amount of RNA present in the template to assess biotemplate-nanomaterial property relationships. Produced nanoparticles were probed with several techniques including UV-Vis, photoluminescence and Hi-Res TEM. Optical techniques revealed that CdS nanoparticles with predicated fluorescent properties form in the presence of MS2 and remain stable in aqueous solutions. In fact, MS2-templated CdS nanoparticles were stable at room temperature for several weeks. Presence of RNA in the capsid interior was found to have major impact on the biotemplating process. Hi-Res TEM micrographs verified the presence of nanocrystals and their association with the biotemplate. Bionanofabrication using viral templates holds promise to enable an efficient, controlled and environmentally sustainable synthesis approach for a range of important nanomaterials. The work presented here represents an additional step forward towards those goals.
The Cytotoxicity of Quantum Dots CdSe/CdS functionalized with -COOH and –NH2
Authors: Shen Lin-Jing , Cui Jing , Liu Jin-Hua , Xu Xiao-Bo , Zhu Ming-Qiang 
Published: January 2010

AbstractRecently, semiconductor nanocrystals or quantum dots (QDs) aroused great concern because of their unique properties such as the size-dependent photoluminescence. They have many excellent applications in areas of molecular bioimaging, medical detection and even energy, especially as biosensing and imaging instead of fluorescent dyes. For the bio-safety, however, we should assess the cytotoxicity of QDs before used in biomedical imaging. Here, the cytotoxicity of amino-functionalized CdSe/CdS (CdSe/CdS-NH2) QDs and carboxy-functionalized CdSe/CdS (CdSe/CdS-COOH) QDs was investigated by MTT assay method. According to our findings, both CdSe/CdS-NH2 and CdSe/CdS-COOH have a dose-dependent effect on cell proliferation. The cytotoxicity of QDs varies with storing time of QDs and kinds of cells. The cytotoxicity of QDs modified with -COOH or -NH2 groups both vary with concentrations in positive linear or change with QD storing time in negative linear. The results indicate that CdSe/CdS-COOH QDs have lower toxicity than CdSe/CdS-NH2 QDs. Hela cell is somewhat more sensitive to amino- and carboxy-modified QDs than Bel7404 cell for MTT assays.
MEMS Microresonators for High Temperature Sensor Applications
Authors: Doppalapudi Dharanipal , Mlcak Richard , LeClair Jeremie , Gwynne Patrick , Bridgham Jeffrey , Purchase Scott , Skelton Martin , Schultz Gerald , Tuller Harry 
Published: January 2010

AbstractMicroelectromechanical Systems (MEMS) are being extensively investigated as a means of miniaturizing piezoelectric sensors thereby offering higher sensitivity, reduced power consumption, and ability to form compact multi-sensor arrays. Such devices typically employ one or more silicon micromechanical elements (e.g. membranes, cantilever beams and tethered proof masses) driven electromechanically by a polycrystalline piezoelectric film. The use of polycrystalline materials results in inherently less stable and irreproducible device characteristics. For elevated operating temperatures, more robust and refractory materials are also required. In this paper, we describe a MEMS microresonator array capable of operating to temperatures exceeding 600°C enabled by the integration of epitaxially grown piezoelectric AlN films onto single crystal SiC tethered plates. The operation of the microresonators as sensors is illustrated by examining their response to temperature, pressure and chemical analytes.
Mechanical Characterization of Atomic Layer Deposited (ALD) Alumina for Applications in Corrosive Environments
Authors: Ou Kuang-Shun , Lin I-Kuan , Wu Ping-Hsin , Huang Zhi-Kai , Chen Kuo-Shen , Zhang Xin 
Published: January 2010

AbstractIn this work, thin ALD alumina films were fabricated for evaluating their capabilities as a barrier material for corrosive environments. The fracture toughness and the corrosion-resisting properties after fatigue cycle of these thin ALD alumina films have been characterized. Indentation tests indicate that the ALD alumina/Al structures could enhance both the yield strength of the metal and the effective fracture toughness of the coated ALD alumina films and this result could be useful for designing nanocomposite structures. However, the test results also indicate that the interfacial strength of the ALD/Al structures was prone to degrade under fatigue loading under corrosive environment. This could potentially be a problem for the long term reliability of related devices operated under a harsh environment. In addition, the strong correlation between indentation behavior and fatigue loading for the structure indicate that nanoindentation response could be possibly used to indicate the damage level of microstructures for future reliability evaluations.
Synthesis and Characterization of Nanocomposite Thin Films for MEMS Applications
Authors: Das Kaushik , Park Cheol , Le Faive Rosemary , Hubert Pascal , Vengallatore Srikar 
Published: January 2010

AbstractReinforcement with nanotubes, nanofibers, and nanoparticles is an attractive option for enhancing the properties of micromachined polymeric structures employed in microelectromechanical systems (MEMS). Calculations based on Eshelby-Mori-Tanaka micromechanics predict that the elastic modulus and wave velocity can be increased by over an order of magnitude by reinforcing polymers with aligned, dispersed, single-walled carbon nanotubes (SWNT). Motivated by this prediction, we measured the elastic moduli of polyimide films reinforced with SWNT at volume fractions ranging from 0 to 10%. For dilute composites, the elastic modulus increased with increasing nanotube loading from 2.5 GPa for the neat polymer to 3.5 GPa for a nanocomposite containing 0.5 vol% of SWNT. However, with further increase in the nanotube content, the elastic modulus remained essentially constant even for high loadings of 10 vol% of SWNT. In addition, significantly different elastic moduli were measured for specimens containing the same volume fraction (0.5 vol%) of SWNT produced by two different processes.
Stumbling on Extrinsic Effects in Super-hard Nanobuttons
Authors: Rinaldi Antonio , Peralta Pedro , Friesen Cody , Nahar Dhiraj , Licoccia Silvia , Traversa Enrico , Sieradzki Karl 
Published: January 2010

AbstractThe compressive plastic strength of nanosized single crystal metallic pillars is known to depend on the diameter D, but little attention has been given to the pillar height h. The important role of h is analyzed here, observing the suppression of generalized crystal plasticity below a critical value hCR that can be estimated a priori. Novel in-situ compression tests on regular pillars (D = 300-900 nm) as well as nanobuttons (i.e. very short pillars with h less than hCR, such as D = 200 nm and h < 120 nm in this case) show that the latter ones are exceedingly harder than ordinary Ni pillars, withstanding stresses greater than 2 GPa. This h-controlled transition in the plastic behaviour is accompanied by extrinsic plastic effects in the harder nanobuttons. Such effects normally arise as Saint-Venant’s assumption ceases to be accurate. Some bias related to those effects is identified and removed from test data. Our results underline that nanoscale testing is challenging when current methodology and technology are pushed to the limit.
Minoritary Transport in Heavily Doped p-type InGaAs
Authors: Tea Eric , Aniel Frederic 
Published: January 2010

AbstractMinoritary carrier’s transport properties are of fundamental importance in the HBT’s physics. The base transit time is a key parameter to improve microwave figure of merit. Some recent minoritary electron mobilities measurements versus acceptor doping level using magneto transport method exhibit a dramatic increase at very high majority carrier concentration. This effect has been attributed to the coupling of polar optical phonons with hole plasmons (LOPC) which controls the balance between enegy gain by electric field acceleration and energy loss by polar optical phonon emission. We present minoritary mobilities as a function of majority carrier doping calculated in the frame of electrons and holes Monte Carlo modelling including LOPC.
Formation of Elemental Distribution in Glass Using Thermal Accumulation with Femtosecond Laser Irradiation
Authors: Shimizu Masahiro , Miura Kiyotaka , Yasuda Naomi , Sakakura Masaaki , Kanehira Shingo , Nishi Masayuki , Shimotsuma Yasuhiko , Hirao Kazuyuki 
Published: January 2010

AbstractElemental migration inside a glass was induced space-selectively and microscopically by high-repetition femtosecond(fs) laser irradiation. The tendency of the elemental migration depended on the strength of the bond between cations and oxygen ions:strongly bonded ions like Si or Al migrated to the center of the irradiated spot, whereas weekly bonded ions such as Ca migrated to the outside. Judged from analyzed temperature distribution, this phenomenon may be due to the thermomigration(Soret effect). The refractive index distribution was modified locally by controlling elemental distribution and optical waveguide was formed in phosphate and borate glasses.