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Full-Text Articles in Engineering

Binding, Transcytosis And Biodistribution Of Anti-Pecam-1 Iron Oxide Nanoparticles For Brain-Targeted Delivery, Mo Dan, David B. Cochran, Robert A. Yokel, Thomas D. Dziubla Nov 2013

Binding, Transcytosis And Biodistribution Of Anti-Pecam-1 Iron Oxide Nanoparticles For Brain-Targeted Delivery, Mo Dan, David B. Cochran, Robert A. Yokel, Thomas D. Dziubla

Pharmaceutical Sciences Faculty Publications

OBJECTIVE: Characterize the flux of platelet-endothelial cell adhesion molecule (PECAM-1) antibody-coated superparamagnetic iron oxide nanoparticles (IONPs) across the blood-brain barrier (BBB) and its biodistribution in vitro and in vivo.

METHODS: Anti-PECAM-1 IONPs and IgG IONPs were prepared and characterized in house. The binding affinity of these nanoparticles was investigated using human cortical microvascular endothelial cells (hCMEC/D3). Flux assays were performed using a hCMEC/D3 BBB model. To test their immunospecificity index and biodistribution, nanoparticles were given to Sprague Dawley rats by intra-carotid infusion. The capillary depletion method was used to elucidate their distribution between the BBB and brain parenchyma.

RESULTS: Anti-PECAM-1 …


Magnetic Interaction Reversal In Watermelon Nanostructured Cr-Doped Fe Nanoclusters, Maninder Kaur, Qilin Dai, Mark Bowden, Mark H. Engelhard, Yaqiao Wu, Jinke Tang, You Qiang Nov 2013

Magnetic Interaction Reversal In Watermelon Nanostructured Cr-Doped Fe Nanoclusters, Maninder Kaur, Qilin Dai, Mark Bowden, Mark H. Engelhard, Yaqiao Wu, Jinke Tang, You Qiang

Materials Science and Engineering Faculty Publications and Presentations

Cr-doped core-shell Fe/Fe-oxide nanoclusters (NCs) were synthesized at varied atomic percentages of Cr from 0 at. % to 8 at. %. The low concentrations of Cr (%) were selected in order to inhibit the complete conversion of the Fe-oxide shell to Cr2O3 and the Fe core to FeCr alloy. The magnetic interaction in Fe/Fe-oxide NCs (~25 nm) can be controlled by antiferromagnetic Cr-dopant. We report the origin of σ-FeCr phase at very low Cr concentration (2 at. %) unlike in previous studies, and the interaction reversal from dipolar to exchange interaction in watermelon-like Cr-doped core-shell NCs.


Pulsed Laser Coating Of Bioceramic (Hap) And Niti Nanoparticles On Metallic Implants, Aayush Goswami, Gary J. Cheng Oct 2013

Pulsed Laser Coating Of Bioceramic (Hap) And Niti Nanoparticles On Metallic Implants, Aayush Goswami, Gary J. Cheng

The Summer Undergraduate Research Fellowship (SURF) Symposium

This research deals with increasing the biocompatibility of the bio implants which have a global market valued more than $94.1 billion . The surface of the metal alloys used for the bone implants need to be coated with bio compatible materials like HAp(Hydroxyapatite), graphene, etc. in order to promote the growth of cells(osteoblasts) on the surface of the implants. Various techniques like plasma spray coating, ion beam sputter coating, etc. have been used before to coat such materials on a substrate, however these have faced problems of coating quality. In order to perfect this coating, that is make it more …


Electrochemical Sensing With Metal Oxides, Isabella Ramirez, Lia Stanciu, Alexandra Snyder Oct 2013

Electrochemical Sensing With Metal Oxides, Isabella Ramirez, Lia Stanciu, Alexandra Snyder

The Summer Undergraduate Research Fellowship (SURF) Symposium

The effective sensing of hydrogen peroxide is important for a variety of reasons. It can be utilized as a diagnostic tool for diseases like asthma; also, the sensing can be utilized in pharmaceutical and food production for quality control. The use of silver oxide nanoparticles with varying morphologies has not been investigated as a sensing agent for hydrogen peroxide in the past. The particles’ properties and ability to oxidize and reduce hydrogen peroxide suggest that they will be effective to create a sensitive sensor. The silver oxide particles were prepared through chemical reduction using varying molar ratios of reactants. The …


Effect Of Relative Humidity In High Temperature Oxidation Of Ceria Nanoparticles Coating On 316l Austenitic Stainless Steel, Luis Giraldez Pizarro Aug 2013

Effect Of Relative Humidity In High Temperature Oxidation Of Ceria Nanoparticles Coating On 316l Austenitic Stainless Steel, Luis Giraldez Pizarro

Theses and Dissertations

A solution of 20 wt. % colloidal dispersion of Cerium Oxide (CeO2) in 2.5% of acetic acid, was used for depositing a coating film on an austenitic stainless steel 316L. Cerium compounds have been distinguished as potential corrosion inhibitors in coatings over several alloys. The oxidation behavior of the cerium oxide coating on 316L austenitic stainless steel alloy was evaluated in dry and humid environments, the weight changes (W/A) was monitored as a function of time using a custom built Thermogravimetrical Analysis (TGA) instrument at temperatures of 750C, 800C and 850C, and different relative humidity levels (0%, 10% and 20%) …


Tuning The Performance Of Nanocarbon-Based Gas Sensors Through Nanoparticle Decoration, Shumao Cui May 2013

Tuning The Performance Of Nanocarbon-Based Gas Sensors Through Nanoparticle Decoration, Shumao Cui

Theses and Dissertations

Tin dioxide (SnO2) is a well–known gas sensing material, but it becomes sensitive only at elevated temperatures (e.g., above 200 °C). Nanoparticles (NPs) combined with nanocarbons, such as carbon nanotubes (CNTs) and graphene, form a new class of hybrid nanomaterials that can exhibit fascinating gas sensing performance due to tunable electron transfer between NPs and nanocarbons induced by gas adsorption. Indeed, sensors made of SnO2 NPs&ndascoated CNTs have shown outstanding room–temperature sensing performance to various gases, including those that are undetectable by either SnO2 or CNTs alone.

The objectives of this dissertation study are to synthesize …


The Effect Of Nanostructure On The Electrical Properties Of Metal Oxide Materials, Philip Zachary Rice Jan 2013

The Effect Of Nanostructure On The Electrical Properties Of Metal Oxide Materials, Philip Zachary Rice

Legacy Theses & Dissertations (2009 - 2024)

Resistive random access memory (ReRAM) is a potential replacement technology for Flash and other memory implementations. Advantages of ReRAM include increased scalability, low power operation, and compatibility with silicon semiconductor manufacturing. Most of the ReRAM devices described to date have utilized thin film based metal oxide dielectrics as a resistive switching matrix. The goal of this dissertation project has been to investigate the resistive switching behavior of nanoparticulate metal oxides and to develop methods to utilize these materials in ReRAM device fabrication. To this end, nanoparticles of TiO2 and HfO2 were synthesized under a variety of conditions resulting …


Multidentate Resorcinarene Surfactants For The Phase Transfer Of Metal Nanoparticles And Nanodiamonds: Applications In Catalysis And Diamond Film Growth, Vara Prasad Sheela Jul 2012

Multidentate Resorcinarene Surfactants For The Phase Transfer Of Metal Nanoparticles And Nanodiamonds: Applications In Catalysis And Diamond Film Growth, Vara Prasad Sheela

Chemistry & Biochemistry Theses & Dissertations

One main objective of the present work is to functionalize cuboctahedral platinum nanoparticles with various multidentate resorcinarene surfactants and study their influence in determining their catalytic activity. We hypothesized that catalytically active and recyclable catalysts can be achieved by incomplete yet strong passivation of the nanoparticle surfaces by using multidentate resorcinarene surfactants. We have developed phase transfer protocols for functionalizing cuboctahedral platinum nanoparticles with resorcinarene thiol or amine. Fluorescence assay confirmed that both these nanoparticles contained almost comparable unpassivated metal area. The activity of such phase transferred nanoparticles was tested in the catalytic hydrogenation of allyl alcohol. The conversion of …


The Synthesis And Characterization Of Gold And Silver Nanoparticles In Formal And Informal Settings, Mathew Wynn Jun 2012

The Synthesis And Characterization Of Gold And Silver Nanoparticles In Formal And Informal Settings, Mathew Wynn

Materials Engineering

Silver nanoparticles were synthesized through the reduction of AgNO3 using NaBH4. The borohydride anions were adsorbed onto silver nanoparticles. The repelling forces of the borohydride anions prevented the aggregation of particles, but the addition of an electrolyte or agitation induced aggregation. A yellow hue was given off by the silver nanoparticle sol that, using a spectrophotometer, had plasmon resonance at 386 nm. The silver nanoparticles were estimated to be 10 to 20 nm in diameter. Gold nanoparticles were synthesized through the reduction of HAuCl4 using Na3C6H5O7. The gold nanoparticle sol gave off a red hue that had plasmon resonance at …


The Effects Of Concentration, Stir Rate, And Processing Temperature On The Iridescence Of Polymethyl Methacrylate Nanoparticles, David Baruela Jun 2012

The Effects Of Concentration, Stir Rate, And Processing Temperature On The Iridescence Of Polymethyl Methacrylate Nanoparticles, David Baruela

Materials Engineering

Synthetic opals were synthesized by creating polymethyl methacrylate (PMMA) nanospheres in order to determine which conditions would create the best iridescent samples. The factors affecting the iridescence were nanosphere concentration, stir rate, and processing temperature. PMMA solutions were made by adding 17 mg of granular azobis to a solution of 16 mL of distilled water with 3 mL of methyl methacrylate (MMA). The solution was stirred at different rates, slow and fast, and different temperatures, 70 °C and 90 °C, under a constant flow of nitrogen gas for 40 minutes until the polymerization reaction was complete. Glass substrates were prepared …


Nanoparticles In Solution-Derived Chalcogenide Glass Films, Spencer Novak May 2012

Nanoparticles In Solution-Derived Chalcogenide Glass Films, Spencer Novak

All Theses

The results in this thesis are from our efforts to modify the optical properties of solution-derived chalcogenide glass films by the incorporation of nanomaterials. First, the composition Ge23Sb7S70 was selected as the appropriate glass matrix for testing because solution-derived films of this composition have been well-studied in our group. Additionally, this composition was found to be less sensitive to certain processing parameters than As2S3, another well-studied, candidate chalcogenide glass composition, making Ge23Sb7S70 more suitable for the addition of nanomaterials. Optimization of film process parameters was performed to obtain high-quality films appropriate for doping with nanomaterials. This consisted of determining the …


Structural Dna Origami: Engineering Supermolecular Self-Assembly For Nanodevice Fabrication, Craig Marshal Onodera May 2012

Structural Dna Origami: Engineering Supermolecular Self-Assembly For Nanodevice Fabrication, Craig Marshal Onodera

Boise State University Theses and Dissertations

Two challenges encountered in nanotechnology are the ability to create nanostructures inexpensively and the ability to arrange nanomaterials with a precision commensurate with their size. In nature, nanostructures are created using a bottom-up approach, whereby molecules hierarchically self-assemble into larger systems. Similarly, structural DNA nanotechnology harnesses the programmability, specificity, and structural integrity of DNA to engineer synthetic, self-assembled materials. For example, during scaffolded DNA origami, a long single stranded DNA polymer is artificially folded into nanostructures using short oligonucleotides. Once folded, two- and three-dimensional nanostructures may be decorated with proteins, metallic nanoparticles, and semiconductor quantum dots. Using gold nanoparticles and …


Ultrafast Electron Diffraction Study Of The Dynamics Of Antimony Thin Films And Nanoparticles, Mahmoud Abdel-Fattah Jul 2011

Ultrafast Electron Diffraction Study Of The Dynamics Of Antimony Thin Films And Nanoparticles, Mahmoud Abdel-Fattah

Electrical & Computer Engineering Theses & Dissertations

The ultrafast fast phenomena that take place following the application of a 120 fs laser pulse on 20 nm antimony thin films and 40 nm nanoparticles were studied using time-resolved electron diffraction. Samples are prepared by thermal evaporation, at small thickness (< 10 nm) antimony nanoparticles form while at larger thicknesses we get continuous thin films.

The samples are annealed and studied by static heating to determine their Debye temperatures, which were considerably less than the standard value. The thermal expansion under static heating also yielded the expansion coefficient of the sample material. Nanoparticle samples gave a very accurate thermal expansion coefficient (11 × 10-6 K-1).

Ultrafast time resolved electron diffraction …


Optimizing The Performance Of A Glass-Ceramic Storage Phosphor As An Imaging Plate For Medical Use, Manh Vu May 2011

Optimizing The Performance Of A Glass-Ceramic Storage Phosphor As An Imaging Plate For Medical Use, Manh Vu

Masters Theses

Europium-doped-fluorochlorozirconate glass ceramics, known as ZBLAN, were produced in a glove box which has a controlled environment of argon gas. For imaging applications BaCl2 is used instead of BaF2. Their properties after different thermal processing and different amounts of europium-doping were investigated. After annealing the ZBLAN glass, BaCl2 nanoparticles are precipitated in the glass matrix. These glass ceramic storage phosphors are strong candidates for replacing traditional x-ray screen film system and commercial storage phosphors such as Agfa MD-30.

Differential scanning calorimetry (DSC) was used to determine the crystallization temperature of the hexagonal phase of BaCl2 …


Analysis Of Interband, Intraband, And Plasmon Polariton Transitions In Silver Nanoparticle Films Via In Situ Real-Time Spectroscopic Ellipsometry, S. A. Little, R. W. Collins, S. Marsillac Mar 2011

Analysis Of Interband, Intraband, And Plasmon Polariton Transitions In Silver Nanoparticle Films Via In Situ Real-Time Spectroscopic Ellipsometry, S. A. Little, R. W. Collins, S. Marsillac

Electrical & Computer Engineering Faculty Publications

The dielectric function of Ag nanoparticle films, deduced from an analysis of in situ real-time spectroscopic ellipsometry (RTSE) measurements, is found to evolve with time during deposition in close consistency with the film structure, deduced in the same RTSE analysis. In the nucleation regime, the intraband dielectric function component is absent and plasmon polariton behavior dominates. Only at nuclei contact, does the intraband amplitude appear, increasing above zero. Both intraband and plasmon amplitudes coexist during surface smoothening associated with coalescence. The intraband relaxation time increases rapidly after surface smoothening is complete, also in consistency with the thin film structural evolution.


Mixing Of Nanosize Particles By Magnetically Assisted Impaction Techniques, James V. Scicolone Jan 2011

Mixing Of Nanosize Particles By Magnetically Assisted Impaction Techniques, James V. Scicolone

Dissertations

Nanoparticles and nanocomposites offer unique properties that arise from their small size, large surface area, and the interactions of phases at their interfaces, and are attractive for their potential to improve performance of drugs, biomaterials, catalysts and other highvalue- added materials. However, a major problem in utilizing nanoparticles is that they often lose their high surface area due to grain growth. Creating nanostructured composites where two or more nanosized constituents are intimately mixed can prevent this loss in surface area, but in order to obtain homogeneous mixing, de-agglomeration of the individual nanoparticle constituents is necessary.

Due to high surface area, …


Characterisation Of Nanoparticle Through Sem, Ftir, Xrd & Dsc, Ajit Behera Jan 2011

Characterisation Of Nanoparticle Through Sem, Ftir, Xrd & Dsc, Ajit Behera

Ajit Behera

Nanoparticles are widely due as Sustained Release Drug Delivery System. Due to their smaller size of controlled drug release potential, targeting ability, enhancement of therapeutic efficacy and reduction of toxicity. Nifedipine one of the calcium channel blocker use for the management of hypertension. Spray drier technique develops Nifedipine loaded nanoparticle. Primary superimulsion phase contains Drug (Nifedipine), Polymer (Ethylcellulose) & suitable non-aqueous Solvent (Dichloromethane) which are sprayed over secondary phase containing aqueous solvent with dispersing polymers (PVA) are prepared by taking drug to polymer weight ratio of 20:90. Formation of films on the surface of secondary phase dried, sieved & forward …


Novel Magnetic Materials For Sensing And Cooling Applications, Anurag Chaturvedi Jan 2011

Novel Magnetic Materials For Sensing And Cooling Applications, Anurag Chaturvedi

USF Tampa Graduate Theses and Dissertations

The overall goals of the present PhD research are to explore the giant magnetoimpedance (GMI) and giant magnetocaloric (GMC) effects in functional magnetic materials and provide guidance on the optimization of the material properties for use in advanced magnetic sensor and refrigeration applications.

GMI has attracted growing interest due to its promising applications in high-performance magnetic sensors. Research in this field is focused on the development of new materials with properties appropriate for practical GMI sensor applications. In this project, we have successfully set up a new magneto-impedance measurement system in the Functional Materials Laboratory at USF. We have established, …


Programmable Periodicity Of Quantum Dot Arrays With Dna Origami Nanotubes, Hieu Bui, Craig Onodera, Carson Kidwell, Yerpeng Tan, Elton Graugnard, Wan Kuang, Jeunghoon Lee, William B. Knowlton, Bernard Yurke, William L. Hughes Sep 2010

Programmable Periodicity Of Quantum Dot Arrays With Dna Origami Nanotubes, Hieu Bui, Craig Onodera, Carson Kidwell, Yerpeng Tan, Elton Graugnard, Wan Kuang, Jeunghoon Lee, William B. Knowlton, Bernard Yurke, William L. Hughes

Materials Science and Engineering Faculty Publications and Presentations

To fabricate quantum dot arrays with programmable periodicity, functionalized DNA origami nanotubes were developed. Selected DNA staple strands were biotin-labeled to form periodic binding sites for streptavidin-conjugated quantum dots. Successful formation of arrays with periods of 43 and 71 nm demonstrates precise, programmable, large-scale nanoparticle patterning; however, limitations in array periodicity were also observed. Statistical analysis of AFM images revealed evidence for steric hindrance or site bridging that limited the minimum array periodicity.


Fabrication Of Fluorescent Nanoparticle-Polymer Composites For Photoactive-Based Materials, Brett Ellerbrock Aug 2010

Fabrication Of Fluorescent Nanoparticle-Polymer Composites For Photoactive-Based Materials, Brett Ellerbrock

All Theses

Nanocomposites of nanoparticles dispersed throughout a polymer matrix have been studied to great length to improve the overall polymer properties. These enhancements are observed in the thermal, physical, and/or optical characteristics. Being able to harness nanoparticles in such a way may help improve fiber technology into the 21st century.
This work was geared toward synthesizing rare earth doped lanthanum fluoride (LaF3) nanoparticles because good separation in the absorption and emission bands of the material and it fluoresces in the visible to near-infrared range. Terbium ions were added to a LaF3 crystal because of their distinct visible green …


Micro- To Macroscopic Observations Of Mnalpo-5 Nanocrystal Growth In Ionic-Liquid Media, Eng-Poh Ng Dr. Jan 2010

Micro- To Macroscopic Observations Of Mnalpo-5 Nanocrystal Growth In Ionic-Liquid Media, Eng-Poh Ng Dr.

Eng-Poh Ng

Micro- and macroscopic studies of nucleation and growth processes of MnAlPO-5 nanosized crystals under ionothermal synthesis conditions are reported herein. The samples treated at 150 8C were extracted from the reaction mixture at various stages of crystallization, and characterized by XRD; SEM; thermogravimetric analysis (TGA); 31P and 27Al solid-state magic angle spinning (MAS) NMR, Raman, UV/Vis, and X-ray fluorescence spectroscopy (XRF). The starting raw materials (alumina, manganese, and phosphorous) were dissolved completely in the ionic liquid and transformed into an amorphous solid after 5 h of ionothermal treatment. This amorphous solid then undergoes structural changes over the following 5–25 h, …


Photoelectrochemical Properties Of Tio_2 Nanoparticles, Jie Qu, Ying Li, Qi-Wei Jiang, Xue-Ping Gao Feb 2009

Photoelectrochemical Properties Of Tio_2 Nanoparticles, Jie Qu, Ying Li, Qi-Wei Jiang, Xue-Ping Gao

Journal of Electrochemistry

The protonated titanate nanoparticles were obtained at room temperature and subsequently calcined at different temperatures(300 ℃,400 ℃,500 ℃,600 ℃ and 700 ℃) in air.The obtained products were characterized by XRD,TEM and UV-Vis.It is found that the grain sizes of TiO2 nanoparticles calcined at 300 ℃ were about 20 nm,and increased gradually with the temperature rise.Photoelectric performance was measured with I~V curve and electrochemical impedance spectroscopy(EIS).The TiO2 nanoparticles obtained at 500 ℃ showed the best photoelectrochemical properties with a photovoltaic conversion efficiency of 6.39%,which is much higher than those at other temperatures.In addition,it is also demonstrated that the charge transfer resistance …


Functionalized Nanoparticles For Biological Imaging And Detection Applications, Bing C Mei Feb 2009

Functionalized Nanoparticles For Biological Imaging And Detection Applications, Bing C Mei

Doctoral Dissertations 1896 - February 2014

Semiconductor quantum dots (QDs) and gold nanoparticles (AuNPs) have gained tremendous attention in the last decade as a result of their size-dependent spectroscopic properties. These nanoparticles have been a subject of intense study to bridge the gap between macroscopic and atomic behavior, as well as to generate new materials for novel applications in therapeutics, biological sensing, light emitting devices, microelectronics, lasers, and solar cells. One of the most promising areas for the use of these nanoparticles is in biotechnology, where their size-dependent optical properties are harnessed for imaging and sensing applications. However, these nanoparticles, as synthesized, are often not stable …


Spectroscopic Investigation Of Palladium-Copper Bimetallic Systems For Pem Fuel Cell Catalysts, Timo Hofmann Jan 2009

Spectroscopic Investigation Of Palladium-Copper Bimetallic Systems For Pem Fuel Cell Catalysts, Timo Hofmann

UNLV Theses, Dissertations, Professional Papers, and Capstones

One of the main barriers to commercialization of polymer electrolyte membrane fuel cells systems is cost, which is largely due to the need of platinum (Pt)-containing catalysts. In this thesis we investigate bimetallic systems consisting of a base metal (copper) and a noble metal (palladium) that, as an alloy on the nanoscale, mimic the electronic properties that make Pt desirable as a catalyst.

We present a detailed investigation of the electronic structure of carbon-supported Pd/Cu nanoparticle catalysts, model bilayer thin film systems, alloys, and various metal reference samples. We have investigated the valence band structure of the catalysts using a …


Observed Superspin-Glass Behavior In Ni0.5zn0.5fe2o4 Nanoparticles, Antony Adair Jan 2009

Observed Superspin-Glass Behavior In Ni0.5zn0.5fe2o4 Nanoparticles, Antony Adair

Open Access Theses & Dissertations

In this investigation we seek to identify the magnetic behavior of Ni0.5Zn0.5Fe2O4 nanoparticles though AC-susceptibility and DC-magnetization measurements. Powder x-ray diffraction was performed to determine the purity and average diameter ( ~ 9nm) of the particles. Aditionally, structure was confirmed by comparison through the International Centre for Diffraction Data's Powder Diffraction File [52] (PDF # 08-0234).

Zero-field cooled and field cooled DC magnetization measurements (bifurcation and blocking temperature), as well as M(H) hysteresis (below and above the blocking temperature) lead us to initially suggest that the material may in fact be superparamagnetic. However, further investigation of the real AC susceptibility …


An Ultrahigh Vacuum Complementary Metal Oxide Silicon Compatible Nonlithographic System To Fabricate Nanoparticle-Based Devices, Arghya Banerjee, Biswajit Das Mar 2008

An Ultrahigh Vacuum Complementary Metal Oxide Silicon Compatible Nonlithographic System To Fabricate Nanoparticle-Based Devices, Arghya Banerjee, Biswajit Das

Electrical & Computer Engineering Faculty Research

Nanoparticles of metals and semiconductors are promising for the implementation of a variety of photonic and electronic devices with superior performances and new functionalities. However, their successful implementation has been limited due to the lack of appropriate fabrication processes that are suitable for volume manufacturing. The current techniques for the fabrication of nanoparticles either are solution based, thus requiring complex surface passivation, or have severe constraints over the choice of particle size and material. We have developed an ultrahigh vacuum system for the implementation of a complex nanosystem that is flexible and compatible with the silicon integrated circuit process, thus …


Probing And Tuning The Size, Morphology, Chemistry And Structure Of Nanoscale Cerium Oxide, Satyanarayana Kuchibhatla Jan 2008

Probing And Tuning The Size, Morphology, Chemistry And Structure Of Nanoscale Cerium Oxide, Satyanarayana Kuchibhatla

Electronic Theses and Dissertations

Cerium oxide (ceria)-based materials in the nanoscale regime are of significant fundamental and technological interest. Nanoceria in pure and doped forms has current and potential use in solid oxide fuel cells, catalysis, UV- screening, chemical mechanical planarization, oxygen sensors, and bio-medical applications. The characteristic feature of Ce to switch between the +3 and + 4 oxidation states renders oxygen buffering capability to ceria. The ease of this transformation was expected to be enhanced in the nanoceria. In most the practical scenarios, it is necessary to have a stable suspension of ceria nanoparticles (CNPs) over longer periods of time. However, the …


High Performance Zno Varistors Prepared From Nanocrystalline Precursors For Miniaturised Electronic Devices, Suresh Pillai, Declan Mccormack, John Kelly, Raghavendra Ramesh Jan 2008

High Performance Zno Varistors Prepared From Nanocrystalline Precursors For Miniaturised Electronic Devices, Suresh Pillai, Declan Mccormack, John Kelly, Raghavendra Ramesh

Articles

An industrially viable solution-based processing route using minimal amounts of solvent has been used to prepare bulk quantity nanopowders (average particle size 15.3 nm) for the fabrication of ZnO varistors. The xerogels, calcined powders and sintered materials were fully characterised. The preparation of varistors from nanopowders has been optimised by studying the effect of temperature on grain growth, densification and breakdown voltage. The varistors are prepared by sintering at 1050 C for 2 hours, a temperature that is significantly lower than that used in the current industrial process. Highly dense varistor discs prepared from the sintered material produce devices, with …


A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Shizhi Qian, Marcos A. Cheney, Pradip K. Bhowmik, Sang W. Joo, Wensheng Hou, Joseph M. Okoh Jan 2008

A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Shizhi Qian, Marcos A. Cheney, Pradip K. Bhowmik, Sang W. Joo, Wensheng Hou, Joseph M. Okoh

Mechanical Engineering Faculty Research

A new method for preparing black birnessite nanoparticles is introduced. The initial synthesis process resembles the classical McKenzie method of preparing brown birnessite except for slower cooling and closing the system from the ambient air. Subsequent process, including wet-aging at 7◦C for 48 hours, overnight freezing, and lyophilization, is shown to convert the brown birnessite into black birnessite with complex nanomorphology with folded sheets and spirals. Characterization of the product is performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N2 adsorption (BET) techniques. Wet-aging and lyophilization times are shown to …


Electrodeposition Of Nano-Sb-Zn Alloy In Acetamide-Urea-Nabr-Kbr Melt, Peng Liu, Xin-Ai Guo, Ye-Xiang Tong, Qi-Qin Yang Aug 2006

Electrodeposition Of Nano-Sb-Zn Alloy In Acetamide-Urea-Nabr-Kbr Melt, Peng Liu, Xin-Ai Guo, Ye-Xiang Tong, Qi-Qin Yang

Journal of Electrochemistry

The electroreduction of Zn(II) and Sb(III) in acetamide-urea-NaBr-KBr(343 K) were studied by cyclic volatmmetry.The reduction of Zn(II) or Sb(III) to the metals is an irreversible process.The transfer coefficient of Zn(II)+2e→Zn and Sb(III) +3e→Sb were calculated to be 0.231 and 0.319,the diffusion coefficient of Zn(II) and Sb(III) in the melt were determined as 1.70 10~(-6) and 3.21 10~(-6) cm~(2)· s~(-1) respectively.The Zn-Sb films with different Zn content from 29.67 at% to 97.34 at% were electrodeposited in acetamide-urea-NaBr-KBr melt at 343 K by controlling the deposition potential and the Zn(II)/Sb(III) molar ratio.The morphology of Zn-Sb film was observed by SEM.Zn-Sb film comprises …