Nanoscience and Nanotechnology Commons^™

Imaging Using Lateral Bending Modes Of Atomic Force Microscope Cantilevers, A. Caron, U. Rabe, M. Reinstadtler, Joseph A. Turner, W. Arnold

Nebraska Center for Materials and Nanoscience: Faculty Publications

Using scanning probe techniques, surface properties such as shear stiffness and friction can be measured with a resolution in the nanometer range. The torsional deflection or buckling of atomic force microscope cantilevers has previously been used in order to measure the lateral forces acting on the tip. This letter shows that the flexural vibration modes of cantilevers oscillating in their width direction parallel to the sample surface can also be used for imaging. These lateral cantilever modes exhibit vertical deflection amplitudes if the cantilever is asymmetric in thickness direction, e.g., by a trapezoidal cross section.

Attenuation Of Ultrasonic Waves In Rolled Metals, Liyong Yang, Joseph A. Turner

Nebraska Center for Materials and Nanoscience: Faculty Publications

Scattering of ultrasonic waves in polycrystals with texture is studied in this article. The attenuations of the three wave modes are determined as a function of dimensionless frequency and propagation direction, respectively, for given orientation distribution coefficients (ODCs). The calculation is done in the case of a statistically orthorhombic sample made up of cubic crystallites. The wave propagation and scattering model is formulated by the Dyson equation using an anisotropic Green’s function approach.Within the limits of the first-order smoothing approximation, the Dyson equation is solved in the spatial Fourier transform domain. The results presented are shown to be directional dependent, …

Electrocatalytic Performances Of Carbon Nanotube Air Electrode For Oxygen Reduction, Feng-Ming Zhao, Chun-An Ma

Journal of Electrochemistry

The air electrodes with different mass ratio of Pt/active carbon or carbon nanotube as catalyst layer material have been prepared. The electrocatalytic performances for oxygen reduction were evaluated by means of polarization curve and electrochemical impedance spectroscopy (EIS). The results disclosed that carbon nanotubes dealt with nitric acid in the catalyst layer had been improved obviously on the electrocatalytic activity. After the surface of carbon nanotube was oxygenated and aggraded with platinum, the catalyst had obviously effects on the electrocatalytic activity. The air electrode with the mass ratio of active carbon to Pt/carbon nanotube in 4∶1 showed better electrocatalytic activity, …

Science For Stewardship: Multidisciplinary Research On Uss Arizona, Matthew A. Russell, Larry E. Murphy, Donald L. Johnson, Timothy J. Foecke, Pamela J. Morris, Raphy Mitchell

Department of Mechanical and Materials Engineering: Faculty Publications

The National Park Service’s Submerged Resources Center and USS Arizona Memorial are conducting and coordinating research directed at understanding the nature and rate of natural processes affecting the deterioration of the USS Arizona in Pearl Harbor, Hawaii. The USS Arizona Preservation Project is designed to be multi-year, interdisciplinary and cumulative, with each element contributing to developing an overall management strategy designed to minimize environmental hazard from fuel oil release and provide the basic research required to make informed management decisions for long-term preservation. The primary project focus is toward acquiring requisite data for understanding the complex corrosion and deterioration processes …

Mechanical Properties Of Carbon Nanotubes Composites, David Hui, Mircea Chipara, Jagannathan Sankar, K. T. Lau

Physics and Astronomy Faculty Publications and Presentations

A critical review of theoretical models aiming to explain the physical properties of composites based on polymeric matrices reinforced with carbon nanotubes is presented. Attention is paid to descriptions based on molecular dynamics, continuum mechanics, and finite element analysis. It is shown that both the continuum mechanics approximation and the finite size element analyses fail to describe composites with very thin interfaces, while the performances of molecular dynamics simulations are still restricted by computer's performances. The limitations of the continuum mechanics approximation are analyzed in detail.

Lithium Insertion Into Tio_2(B) Nanobelts Synthesized By The "Soft Chemical" Method, Cha-Geng Nie, Zheng-Liang Gong, Lan Sun, Juan Zuo, Yue-Kun Lai, Chang-Jian Lin

Journal of Electrochemistry

TiO_(2)(B) Nanobelts were synthesized by using the "Soft chemical"method. The products were characterized by means of transmission electron microscope(TEM), X-ray diffraction(XRD), Raman spectrum and energy dispersive spectrum(EDS). Galvanostatic charging and discharging tests showed that lithium-ion intercalation/deintercalation occurred reversibly in the TiO_(2)(B) nanobelts electrode, and a high capacity (265 mAh·g~(-1)) can be obtained. The results suggested that TiO_(2)(B) Nanobelts might be a promising negative electrode material of second Lithium battery.

Chemical Microetching Of Three-Dimensional Gear-Like Pattern On Nickel Surface, Zhu-Fang Liu

Journal of Electrochemistry

The chemical micromachining on nickel surface with three-dimensional (3D) gear-like mold was realized by confined etchant layer technique (CELT). By using effective chemical etching and scavenging system (HNO_(3) + NaOH) and optimizing experimental parameters, such as the etching time, etching current density, concentration of the etchant or and scavenger, we obtained the etched pattern, which is close to negative copy of the mold. The etched micro-pattern characterized by SEM and AFM, demonstrates that CELT can be applied to the 3-D microstructure replication on nickel surface .

Electrochemical Lithium Insertion Of Nanosized Tio_2, Ying Lan, Jian-Wen Liu, Xue-Ping Gao, Xing-Di Zhou, Jin-Qiu Qu, Feng Wu, De-Ying Song

Journal of Electrochemistry

The protonic titanate nanotubes with the diameter of 10～15 nm were synthesized via hydrothermal method in NaOH solution and the calcined nanotubes at 500 ℃ were transferred to anatase nanorods with the diameter of 12～20 nm due to dehydration.The electrochemical behavior of the anatase nanorods as lithium insertion materials was examined. The results showed that the nanorod electrode had the high initial discharge capacity of 232 mAh/g and second reversible capacity of 198 mAh/g. The capacity of nanorod electrode maintained 152mAh/g after 20 cycles.

Studies Of Infrared Optical Properties Of Palladium Nanoparticles With Different Sizes And Dispersed States, Yan-Xia Jiang, Hong-Gang Liao, Wei Chen, Shi-Gang Ment Of Chemistry Xiamen University Sun, Xiamen Xiamen, China China

Journal of Electrochemistry

Pd nanoparticles with different sizes and dispersed states were prepared. Their infrared optical properties were studied with CO molecule probe. The infrared spectroscopic investigation revealed that Pd_(n)of 6.6 nm and Pd_n~(cube)of 100～150nmexhibit normal IR absorption. The center of IR bands are around 1 970 cm~(-1 )and 1 910cm~(-1). Pd_(n)is introduced into the surface of electrode, and is induced by interface electric fieldto form the aggregation of nanoparticles Pd_n~(ag). The Pd_n~(ag)has a different IR optical property from Pd_(n). The direction of IR absorption band of Pd_n~(ag)is changed from normal to abnormal at 1 970cm~(-1)with the increase of polarization time. The present …

Direct Electron Transfer Of Redox Proteins And Enzymes Promoted By Carbon Nanotube, Chen-Xin Cai

Journal of Electrochemistry

The redox proteins (enzymes), such as hemoglobin (Hb), horseradish peroxidase (HRP) and glucose oxidase (GOx) were immobilized on the surface of the carbon nanotube modified with glassy carbon (CNT/GC) electrode, respectively. The experimental results showed that the redox proteins (enzymes) underwent effective and stable direct electron transfer reaction at the surface of CNT/GC electrode with a pair of nearly symmetrical redox peaks in phosphate buffer solution. The formal redox potential, E~(0'), is almost independent on the scan rates, the average value of E~(0') for Hb, HRP and GOx is -0.343±0.001, -0.319±0.002 and -0.456±0.001 V (vs.SCE,pH 6.9), respectively. The dependence of …

Preparation And Optical Properties Of Highly Ordered Cds Nanowire Arrays, Lan Sun, Chang-Jian Lin

Journal of Electrochemistry

Highly ordered CdS nanowire arrays have been prepared by using dc electrodeposition in the porous anodic aluminum oxide template. Scanning electro microscopy (SEM) and transmission electron microscopy (TEM) reveal that the nanowires are uniform and highly ordered. The measurements of X-ray diffraction and high-resolved electron microscopy (HRTEM) show that the nanowires are hexagonal structure with the crystallographic c-axis preferentially oriented along the length of the pore. The UV-Vis absorption spectra of CdS nanowire arrays show that the absorption edges of the nanowire arrays shift towards short wavelength with the decrease of the nanowire size. The photoluminescence measurements show that the …

Study On Reduction Process Of Electrolyic Manganese Dioxide In Situ By Ultraviolet-Visible Absorption Spectroscopy, Li-Cai Zhu, Zhong-Zhi Yuan, Wei-Shan Li

Journal of Electrochemistry

The concentrationsof soluble Mn(Ⅲ) species,during the reduction ofelectrolytic MnO_(2) (EMD)in alkaline solution,have been monitored in situ by UV-visible spectroscopy. The concentration of Mn(Ⅲ) ion in solution changes with discharge time.The first electron discharge process of EMD can be described by three different steps: 1) the reduction of Mn~(4+)ions on the surface of EMD particles and the structural defect regions within the EMD,2) the reduction of Mn~(4+)ions in ramsdellite,3)the reduction of Mn~(4+)ions in pyrolusite. During the second electron discharge of EMD, the soluble Mn(Ⅲ) is reduced to Mn(Ⅱ) , then Mn(OH)_(2)and Mn_(3)O_(4)are formed.

Development Of Nanostructure Based Corrosion-Barrier Coatings On Steel For Transmutation Applications, Biswajit Das

Transmutation Sciences Materials (TRP)

The objective of this project is to develop a novel nanostructure based coating technology that will provide significantly improved corrosion resistance for steel in LBE at elevated temperatures (500 - 600^oC), as well as provide long-term reliability under thermal cycling. The nanostructure based coatings will consist of a layer of nanoporous alumina with the pores filled with an oxidizing metal such as Cr, followed by a capping layer of alumina. Alumina, which is a robust anti-corrosion material, provides corrosion resistance at elevated temperatures. The Cr serves two purposes: (1) it acts as a solid filler material for the …

Highly Selective, Electrically Conductive Monolayer Of Nanoparticles On Live Bacteria, V Berry, Rangaswamy S, Ravi F. Saraf

Papers in Nanotechnology

Using specific peptide−bacteria affinity, a monolayer of 30 nm Au particle is selectively deposited on live bacteria surface to produce electrically conducting bridges spanning over 12 μm. The conductivity of the monolayer network is further improved by over 10-fold by “electric-field annealing”. The annealing process is explained by a percolation model.

Nanotube Magnetism, Yucheng Sui, Ralph Skomski, Kory D. Sorge, David J. Sellmyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

FePt and Fe3O4 nanotubes are produced by hydrogen reduction in nanochannels of porous alumina templates and investigated by electron microscopy, x-ray diffraction analysis, and magnetic measurements. Loading the templates with a Fe chloride and Pt chloride mixture followed by hydrogen reduction at 560 °C leads to the formation of ferromagnetic FePt nanotubes in the alumina pores. Using a Fe nitrate solution, thermally decomposed at 250 °C and reduced in hydrogen for 2.5 h at the same temperature, yields Fe3O4 tubes. The length of the nanotubes is about 50 mm and their diameters range from about 150 to 220 nm, depending …

Humidity Effects On The Determination Of Elastic Properties By Atomic Force Acoustic Microscopy, D.C. Hurley, Joseph A. Turner

Nebraska Center for Materials and Nanoscience: Faculty Publications

We have investigated how ambient humidity can affect quantitative measurements of elastic properties on the nanoscale. Using an emerging technique called atomic force acoustic microscopy (AFAM), two samples were examined: a thin film of fluorosilicate glass and a section of borosilicate glass. When experimental results were analyzed using a simple model of the atomic force microscope cantilever dynamics, values of the tip–sample contact stiffness k* increased approximately linearly with relative humidity. The effect is believed to be due to the presence of a humidity-dependent layer of water on the sample. To account for this, the data analysis model was …

Substrates Made By Electrodeposition For Measuring Electrical Properties Of One Dimensional Nanomaterials, Jin-Xuan Liu, Juan Xiang, Zhong-Qun Tian, Bing-Wei Xiamen University Mao, Xiamen Xiamen, China China

Journal of Electrochemistry

A method to prepare alternating conducting/insulating substrates by electrodeposition-oxidation was established to facilitate I-E measurements of one-dimensional nanomaterial by CT-AFM. The prepared Au/CuO and HOPG/CuO substrates showed low roughness as well as high uniformity of the alternating conducting/insulating structure, Qualitative I-E measurements were performed on a single carbon nanotube attached to the two above-mentioned substrates, both showing metallic characteristics at room temperature and in air.

Preparation, Structure And Electrochemical Hydrogenation Of Carbon Nanotubes Supported Platinum Catalysts, Qing-Gang He, Xiao-Zi Yuan, Xian-Xia Yuan, Zi-Feng Ma

Journal of Electrochemistry

In this paper, Pt/CNTs catalyst was prepared and its electrocatalytic property was studied by obtaining cycling voltammetry curves (C-V) and Tafel curves. In addition, the XRD,XPS and TEM tests were carried out to determine the structure and composition of the catalysts. It can be found that the platinum loading has been increased significantly using a carbon nanotubes support. Dispersion of Platinum was better and gave more active sites. The electrochemical characteristic of Pt/CNTs was also more desirable than that of Pt/C catalyst(Johnson Matthey). In conclusion, carbon nanotubes can played a conspicuous role in "electrogenerative" processes of PEMFC hydrogenation reactor.

Template Synthesis Of Highly Ordered Monocrystalline Metal Nanowire Arrays By A Two-Step Ac Electrodeposition, Juan Xiang, Jing-Hua Tian, Zi-Mian Ni, Zhi-Feng Huang, Bo Liu, Zhong-Qun Tian

Journal of Electrochemistry

The monocrystalline metal nanowire arrays were prepared by using a two-step AC electrodeposition in porous anodic aluminum oxide (AAO) template. The growth mechanism of nanowires was discussed. As a result, it has been found that the second voltage pulse has a considerable effect on the pore-filling ratio, the uniformity and the crystal structure, whereas the initial voltage pulse affects only the pore-filling ratio. Using the two-step AC electrodeposition, a highly ordered monocrystalline metal nanowire arrays with a pore-filling ration above 95% can be easily obtained.

Study On The Electrochemical Impedance Spectroscopy (Eis) Of Al-Bronze At Different Anodic Potentials, Hui Yu, Sa-Ying Dong, Hai-Bo Xu, Ming-Xian Sun

Journal of Electrochemistry

The corrosion dissolution mechanism of Al-bronze has been investigated by Electrochemical Impedance Spectroscopy (EIS) at different anodic potentials. In the active region, the corrosion products are complex compounds of cupreous chloride and the diffusion of CuCl~(-)_2 is the control process of electrochemical reaction. In the transition region, there exhibits two capacitance loops on EIS because CuCl and cupreous oxides films deposit on the electrode surface. In the limiting current region, an inductance loop appears on the EIS because the breakdown of the oxides film leads to serious pit corrosion.

Formation And Characterization Of Water-Repellent Nano Tio_2 Coating And Studying Its Anticorrosion Property, Guang-Xia Shen, Yi-Cong Chen, Chang-Jian Lin

Journal of Electrochemistry

Using ethyl acetoacetate (EAcAc) as a chelating agent, ultra fine TiO_2 sol is prepared. Nano-TiO_2 coatings are deposited on the 316L stainless steel by the dip-coating. Hydrothermal post-treatment leads to crack-free coatings. Meanwhile, the surface struture and properties was optimized. Self-assembly of Hetadecafluorodecyltrimethoxysilane (FSA-13) fabricates hydrophobic layers on the surface of the nano-TiO_2 coatings. Particle sizes of TiO_2 sol was analysed by zeta pals potential analysis, and surface morphology, structure and properties was characterized by contract angle instrument, XRD, and SEM technologies. The results have shown that the surface of coatings is porous, with approx. 375 nm thick, the particle …

Electrodeposition Nanolaminated Growth Of Zinc, Ying Cao, Tian-Hui Shen, Jing-Yuan Yao, Gui-Fu Ding

Journal of Electrochemistry

Nanolaminated growth of the electrodeposition of zinc was studied. The structure and size of crystalline in zinc coatings were investigated by using FEG-TEM and XRD. The corrosion tests of the zinc deposition and the Coatings-Neutral salt spray test were performed, the capability in corrosion resistance of the nanolaminated growth was better than that of others.

Ultrasound Diffusion For Crack Depth Determination In Concrete, S.K. Ramamoorthy, Y. Kane, Joseph A. Turner

Nebraska Center for Materials and Nanoscience: Faculty Publications

The determination of the depth of surface-breaking cracks in concrete specimens using an ultrasound diffusion technique is discussed. Experiments were carried out on precracked concrete specimens of varying crack depths (0%–40% of the specimen thickness). Contact transducers were placed at the specimen surface with source and receiver separated by the crack. Tone-burst excitations over a frequency range of 400–600 kHz were used. At these frequencies, ultrasound is scattered considerably by the heterogeneities in the concrete. In the limit of many scattering events, the evolution of energy may be modeled as a diffusion process. The arrival of the peak diffuse energy …

Bar Clamp Having Ergonomic Handle, M. Susan Hallbeck, Myung-Chul Jung

Department of Mechanical and Materials Engineering: Faculty Publications

The present invention generally relates to a handle assembly for a hand operable bar clamp having a fixed jaw, a movable jaw and a drive for translating the movable jaw towards the fixed jaw. The assembly includes a handgrip and a trigger handle. The handgrip having an elongated rear portion has a generally rounded surface and being contoured to complement the natural transverse curve pf a human palm. The trigger handle is pivotal with respect to the handgrip. The trigger handle included an elongated front portion having a rounded front surface and being contoured to complement the natural palmer curve …

Interfaces, Volume 7, Issue 1 - Winter 2004

INTERFACES: Newsletter of the Nebraska Center for Materials and Nanoscience

Facility Focus (I): Multipurpose X-Ray System Zeng Named Guggenheim Fellow Sigma Xi Honors to CMRA Faculty, Staff and Students Best Paper Awards Degree of Doctor Honoris Causa Recent Patents Facility Focus(II): Equipment Upgrade in Electron Microscopy CMRA Welcomes Fereydoon Namavar Research Spotlight: Stephen Ducharme Spinning Continuous Fibers for Nanotechnology

Jecp/Sp: A Computer Program For Generating Stereographic Projections, Applicable To Specimen Orientation Adjustment In Tem Experiments, Xingzhong Li

Nebraska Center for Materials and Nanoscience: Faculty Publications

In the present work, a computer program was written for generating stereographic projections and was also extended as an application for specimen orientation adjustment in TEM experiments. JECP/SP is a fully functional tool for generating stereographic projections in direct and reciprocal space. JECP/SP has been extended as an application for specimen orientation adjustment using a TEM holder. JECP/SP can be used as a teaching aid for students in crystallography as well as a practical tool for scientists performing TEM experiments.

Air Quality Regulation Policy In Portugal, João F. Gomes

João F Gomes

Ten years after the publication of first air quality laws in Portugal, and seven years after the publication of the respective emission limits, it seems appropriate to analyse the degree of law enforcement by the Portuguese manufacturing industry. Therefore, based on the emission measurements made regularly by ISQ, as the only officially accredited laboratory, a set of about 400 sources is analysed in terms of the compliance with the emission limits regarding total suspended particulate, sulphur dioxide, nitrogen oxides and VOCs. The compliance is evaluated through a non-dimensional parameter and plotted versus the emission flow rate to derive conclusions: it …

Coherent Vibrational Oscillation In Gold Prismatic Monolayer Periodic Nanoparticle Arrays, Wenyu Huang, Wei Qian, Mostafa A. El-Sayed

Wenyu Huang

We studied the ultrafast laser-induced coherent phonon oscillation in prismatic shaped gold nanoparticles assembled in monolayer periodic arrays by using the nanosphere lithographic technique. The amplitude and phase of the oscillation observed by ultrafast pump−probe transient spectroscopy is monitored as the wavelength of the dipolar surface plasmon absorption decreases. At a certain wavelength, the oscillation could not be observed. As the monitoring wavelength decreases further, the sign of the amplitude changes. From the wavelength at which the oscillation is not detected, the dependence of the absorption maxima on the size of the nanoparticles, the changes in the nanoparticle size are …

Development Of Nanostructure Based Corrosion-Barrier Coatings On Steel For Transmutation Applications: Quaterly Report, Biswajit Das

Transmutation Sciences Materials (TRP)

During the past quarter, this project employed one graduate student and two undergraduate student researchers and made the following accomplishments :

• Acquisition of steel samples for experiments

• Design and fabrication of specialized anodization apparatus to accommodate steel samples

• Investigation of adhesiveness of aluminum on steel

• Investigation of effects of anodizing acids on steel to identify most appropriate acid and a suitable barrier material

Microstructural Analysis Of Varistors Prepared From Nanosize Zno, Suresh Pillai, Declan Mccormack, John Kelly, Ramesh Raghavendra

Articles

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