Journal of Nano Research Vols. 18-19

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Authors: P.S. Pa
Abstract: A Newly Designed Cross-Shaped Electrode Tool and the Use of Excimer Irradiation to Assist in Micro-Electrochemical Etching (μ-ECE) Is Presented. It Is a Precise Surface Treatment Method for the Nanoscale Removal of Defective Indium-Tin-Oxide (In2O3SnO2) Conductive Nanostructure from Optical PET-Diaphragms (PET) of Digital Paper Touch-Panels. in the Current Study, 172nm Excimer Irradiation Is Used to Boost the Electrolytic Action of the Cross-Shaped Electrode Tool. Scoring of the PET Surface Is Eliminated and the Workpiece (PET) Feed Rate Can Be Higher with a Consequent Reduction in Production Costs. when Excimer Irradiation Is Used the In2o3sno2 Thin-Films Are More Easily Broken up and the Nano-Particles Escape from the PET Substrate Quickly and Cleanly. The Required Machining Time Is Shortened if Excimer Irradiation Is Used before the Electrochemical Removal Processing (μ-ECE) of the In2O3SnO2 Layer.
Authors: Yasuo Morimoto, Masami Hirohashi, Masanori Horie, Akira Ogami, Takako Oyabu, Toshihiko Myojo, Masayoshi Hashiba, Yohei Mizuguchi, Tatsunori Kambara, Byeong Woo Lee, Etsushi Kuroda, Kazuhiro Yamamoto, Norihiro Kobayashi, Shigehisa Endoh, Kunio Uchida, Tetsuya Nakazato, Katsuhide Fujita, Junko Nakanishi, Isamu Tanaka
Abstract: Single-Wall Carbon Nanotubes (SWCNTs) Were Well-Dispersed Using Ultrasonication to Conduct an Intratracheal Instillation Study. The Geometric Mean Diameter and Length of the SWCNT in Distilled Water Including 0.1 % Triton X-100 Was 44 Nm and 0.69 μm, Respectively. Rats Intratracheally Received 0.2 Mg or 0.4 Mg of SWCNT, and a Control Group Received Intratracheal Instillation of Distilled Water Containing 0.1 % Triton X-100 . The Rats Were then Sacrificed at 3 Days, 1 Week, 1 Month, 3 Months and 6 Months after Instillation. Bronchoalveolar Lavage Fluid (BALF) and Pathological Features Revealed that the Dose of SWCNT Induced Persistent Neutrophil Infiltration in Rat Lungs. In the Cytokine-Induced Neutrophil Chemoattractants (CINCs) Family, the Concentrations of CINC-1 and CINC-2 in the BALF Increased Persistently in the SWCNT-Exposed Groups. the Concentration of HO-1 in the BALF Was Also up-Regulated Persistently in the Exposed Groups. These Data Suggested that Well-Dispersed SWCNT Had an Inflammatory Potential in the Present Study.
Authors: Reza Jafari Nedoushan, Mahmoud Farzin
Abstract: One of the Remarkable Differences between Mechanical Behavior of Nano-Crystalline and Coarse-Grained Materials Is Tension Compression Asymmetry that Has Been Experienced in Nano-Crystalline Materials. In this Paper a Constitutive Model Is Proposed which Considers Dominant Operative Deformation Mechanisms of Nano-Crystalline Materials Including Grain Interior Plasticity, Grain Boundary Diffusion and Grain Boundary Sliding. A Grain Size Dependent Taylor Type Polycrystalline Model Is Used to Predict Grain Interior Deformation. Three Dimensional Relationships Are Proposed to Relate Macro Stress and Strain Rate in Grain Boundary Mechanisms. The Effect of Normal Stress Acting on a Boundary Is Also Considered in Grain Boundary Sliding, Therefore, Effect of Hydrostatic Pressure Is Included in the Model. The Proposed Model Is Used to Predict Strength of Nano-Crystalline Copper in both Tension and Compression and Good Results Are Obtained Comparing with Experimental Data. The Model Also Predicts Various Behaviors of Nano-Crystalline Materials Observed in Literature's Experiments and Molecular Dynamic Simulations. Some Examples Are: Inverse Hall-Petch Effect; Tension and Compression Maximum Strength Grain Sizes; Tension Compression Asymmetry and its Change Vs. Grain Size and Strain Rate and the Yield Locus Shape.
Authors: M. Saranya, A. Nirmala Grace
Abstract: Cus Nanostructures Have Been Successfully Prepared from Copper Chloride with Two Different Sulfur Sources Like Thiourea and Sodium Thiosulphate by Hydrothermal Route at 150oC. The Growth of Cus Nanostructures Were Investigated for Different Reaction Time Periods of 5 Hrs and 24 Hrs Respectively Using Water as Solvent. the as-Synthesized Cus Nanostructures Are Characterized by X-Ray Diffraction (XRD) and Field-Emission Scanning Electron Microscopy (FE-SEM). XRD Pattern Indicates that the Prepared Cus Nanomaterials Are in Pure Hexagonal Phase. Results Show that Cus Nanomaterials with Different Hierarchical Structures Like Urchins, Nanoplates Etc,. Were Obtained at Different Experimental Conditions. A Systematic Investigation of the Final End Products Has Been Done to Elucidate the Formation Mechanism at Different Experimental Parameters. The Optical Properties of the Cus Structures Were Studied by UV-Vis Absorption Analysis, which Showed Broad Absorption in the Visible Region. The Optical Band Gap of the Cus Nanomaterials Were Found as 2.2 Ev and 2.18 Ev for Different Sulfur Sources.
Authors: N.S. Roshima, S. Saravana Kumar, A. Uma Maheswari, Manickam Sivakumar
Abstract: In this Work a Method of Incorporating Anion or Cation Vacancy during Synthesis Stage of CdS Nanoparticles to Induce Defect Level Emission Is Presented. Further the Influence of Temperature on this Vacancy Related Defects Is Also Studied. the as-Prepared Samples with Co-Precipitation Technique Were Heat Treated with Different Time Intervals at a Constant Temperature of 200 °C. From UV-Visible Absorption Spectra, the Band Gap of both the as-Prepared and Heat Treated Samples Are Calculated to Be 3.51 Ev Indicating that there Are No Significant Changes in the Size of Nanoparticles. The Photoluminescence Spectra of both Samples Showed Emission Bands Corresponding to Band Edge and Defect Levels. Further from the Spectra, it Was Observed that the Intensity of Band Edge Luminescence Decreases with Increase of Heat Treatment Duration. This Is due to the Fact that Induced Defects Have Reached the Surface of Nanoparticles.
Authors: Can Serkan Keskin, Semra Yılmazer Keskin, Abdil Özdemir
Abstract: We Report Herein Results of an Investigation of the Assembly of Silver Nanoparticles Mediated by Glutathione (GSH) and Cysteine (Cys) Interaction in the Presence of Metal Ions: Ag+, Cd2+, Co2+, Cu2+, Fe3+, Hg2+, Ni2+, Pb2+, Zn2+. The Silver Nanoparticles Produce Well-Ordered Structures upon Interaction with Glutathione in Variable Acidic Ph Condition and Exhibit Pronounced Changes in their Optical Properties Arising due to Electromagnetic Interaction. The Effect of Selected Metal Ions on the Nature of Complexation as Well as the Variation in the Optical Response due to Variable Degree of Complex Formation Amongst the Particles Have Been Investigated. The Changes in Optical Properties of the Silver Nanoparticles Have Been Accounted for the Complex Formation among the Aggsh, Cys and Metal Ions. The Complexes Have Been Characterized by UV-Vis Spectroscopy, FTIR, and AFM Studies. It Has Been Observed that the New Absorption Peaks Appear and Intensifies Depending on the Cys and Metal Ion Interaction. The Aggsh Nanoparticles Provided a Simple and Rapid Strategy to Detect Cys with the Aid of Metal Ions in Aqueous Solution. Different Metal Ions Give Different UV-Vis Spectra Profile and Show Different Sensitivity. This New Material Allows a Quantitative Assay of Cys down to the Concentration of 1× 10−5 M in Co2+ Ion Complexation. The Mechanism by which Metal Ions Can Bind with both the GSH Modified Ag Nanoparticles and Cys Molecule through Cooperative Metal–ligand Interactions Is Discussed.
Authors: Jian Guang Wang, Peter Kroll
Abstract: We Perform Density Functional Theory Calculations of the Hydrogen-Passivated Topological Silicon Carbide Quantum Dots (QDs) and Investigate their Structural, Electronic and Optical Properties. We Study Clusters Constructed from 3C-Sic with up to 8 Topological Shells, Corresponding to Diameters up to 2.2 Nm, Terminated Homogeneously with either Si-H or C-H Bonds. All Qds Exhibit Tensile Strain (1-5 %) within the Cluster Core. the Larger the Cluster, the Smaller the Strain in the Interior, however. Tensile Strain Increases from the inside of the Cluster towards the outside, Reaches a Maximum at the Second Layer below the Surface, and Vanishes only for Bonds Involving Surface Si or C Atoms. Quantum-Confinement Effects Are Observed for the Energy Gaps and Optical Gaps of SiC QDs. Size Has a Major Impact on the Absorption Edge in Comparison to a Weak Effect on the Photon Energy of the Spectra Maxima. Our Calculations Show that Surface Termination Plays a Crucial Role and Strongly Affects Energy Gaps, Optical Gaps and Optical Spectra. Orbitals around the HOMO-LUMO Gap Predominantly Localize within the Core of the Cluster, with Significant Contributions by the Surface for Si-H Terminated Clusters only.
Authors: Maya Marinova, Alkyoni Mantzari, Ariadne Andreadou, Efstathios K. Polychroniadis
Abstract: In the present work we report on the polytypic transformations taking place in nanoscale dimensions within 6H-SiC crystals. The examined crystals were grown by Liquid Phase Epitaxy using a mixture of Si and Al as solvents. The study concentrated on the differences from the “correct” stacking order of the Si-C bilayers for 6H-SiC leading to the formation of other polytypes. A great variety of sequences was found, which resulted to the appearance of rare short and long period polytypes or individual lamellae having their “own” stacking inside the 6H-SiC matrix. These nanostructured faults which deteriorate the quality of the grown material indicate also their “sensitivity” to any small or even infinitesimal change of the growth conditions, due to the very small energy among them.
Authors: A.J. Martins, M. Benelmekki, V. Teixeira, P.J.G. Coutinho
Abstract: Pt nanoparticles were produced by reverse micelle templating using DTAB. The resulting nanoparticles showed sizes between 250nm and 500nm and formed clusters. Thioglycolic acid (TGA) was covalently attached to the nanoparticle surface as a stabilizer and as. The Pt nanoparticles were dispersed in water and the dependence of its absorvance on the pH of the solution was studied. The spectra showed surface plamon absorption band at 280nm and also red shifted bands that were attributed to clusters of nanoparticles. It was found that the fraction of cluster population depends on the pH of the aqueous solution and that the response of the Pt nanoparticles to pH variations has a memory effect (hysteresis). The possibility of using these Pt nanoparticles in smart labels for food packaging is outlined.
Authors: M. Benelmekki, M. Torrell, E. Xuriguera, F. Vaz, V. Teixeira
Abstract: Active packaging is becoming the most suitable way to control and assure food safety from farm to fork. In this way, commercial products with finely dispersed nanosilver (n-Ag) particles permanently embedded in the containers are already available in the market. New plastic materials with inherent antibacterial properties can be made for this purpose by polymerization or copolymerization of new monomers or by chemical modification and/or blending of polymers. However the development of new materials by use of new monomers leads often to unacceptable high costs and changes in the bulk properties. Sometimes the obtained materials also suffer a poor thermal stability, which limits their processability. A possible alternative is to use of functional coatings, which improves surface properties of a given substrate leaving unchanged its bulk properties. This technology is limited by mechanical properties of the coating and bad adhesion to the substrates. In this work, we propose a new approach to antibacterial silver activity in packaging by implanting Ag clusters in PET (Polyethylene Terephthalate) substrates by DC sputtering technique. To improve the impermeability of the PET to the gases and water vapour, a Ag:TiOx nanofilm with homogeneous Ag nanoclusters distribution was successfully deposited by DC magnetron sputtering on PET

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