Engineering Commons^™

Studies On The Formation Of Dna-Cationic Lipid Composite Films And Dna Hybridization In The Composites, Murali Sastry, Vidya Ramakrishnan, Mrunalini Pattarkine, Krishna N. Ganesh

Faculty Works

The formation of composite films of double-stranded DNA and cationic lipid molecules (octadecylamine, ODA) and the hybridization of complementary single-stranded DNA molecules in such composite films are demonstrated. The immobilization of DNA is accomplished by simple immersion of a thermally evaporated ODA film in the DNA solution at close to physiological pH. The entrapment of the DNA molecules in the cationic lipid film is dominated by attractive electrostatic interaction between the negatively charged phosphate backbone of the DNA molecules and the protonated amine molecules in the thermally evaporated film and has been quantified using quartz crystal microgravimetry (QCM). Fluorescence studies …

Heat Treatment Of Gamma Titanium Aluminide Alloys, Thomas J. Kelly, Michael J. Weimer, Curtiss M. Austin, Blair London, Donald E. Larson Jr., Dean A. Wheeler

Materials Engineering

A gamma titanium aluminide alloy article, is prepared using a piece of a gamma titanium aluminide alloy having a composition capable of forming alpha, alpha-2, and gamma phases. The alpha transus temperature of the gamma titanium aluminide alloy piece is determined. The gamma titanium aluminide alloy piece is consolidated by hot isostatic pressing at a temperature of from about 50 F. to about 250 F. below the alpha transus temperature and at a pressure of from about 10,000 to about 30,000 pounds per square inch, for a duration of from about 1 to about 20 hours. The piece is heat …

Observation Of Magnetic Moments In The Superconducting State Of Yba₂Cu₃O₆.₆, Herbert A. Mook, Pengcheng Dai, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Neutron scattering measurements for YBa₂Cu₃O_6.6 have identified small magnetic moments that increase in strength as the temperature is reduced below T* and further increase below T_c. An analysis of the data shows the moments are antiferromagnetic between the Cu-O planes with a correlation length of longer than 195 Å in the a-b plane and about 35 Å along the c axis. The origin of the moments is unknown, and their properties are discusssed both in terms of Cu spin magnetism and orbital bond currents.

A Substructuring Technique With Application To Spot Weld Placement Design, Yang Wang

Mechanical & Aerospace Engineering Theses & Dissertations

It is quite common in the industry to use various interface methods, such as welding, fasteners, bolts, adhesive bonding, etc., to join substructures together. The quality of the assembled structure is directly related to the type of the interface methods used in the manufacturing process. Thus, it is important to include the interface conditions as part of design variables in any design process. To this end, this work develops a reanalysis method that can efficiently analyze structures with variations on the interface conditions. This reanalysis method is based upon a new two-step substructuring technique. The first step performs substructural level …

Elastic Properties, Strength And Damage Tolerance Of Pultruded Composites, Mrinal Chandra Saha

Mechanical & Aerospace Engineering Theses & Dissertations

Pultruded composites are candidate materials for civil engineering infrastructural applications due their higher corrosion resistance and lower life cycle cost. Efficient use of materials like structural members requires thorough understanding of the mechanism that affects their response. The present investigation addresses the modeling and characterization of E-glass fiber/polyester resin matrix pultruded composites in the form of sheets of various thicknesses.

The elastic constants were measured using static, vibration and ultrasonic methods. Two types of piezoelectric crystals were used in ultrasonic measurements. Finally, the feasibility of using a single specimen, in the form of a circular disk, was shown in measuring …

Time-Resolved Electron Diffraction Studies Of Phase Transitions At Low-Index Germanium Surfaces, Xinglin Zeng

Electrical & Computer Engineering Theses & Dissertations

The phase transitions at the low-index surfaces of germanium were investigated using conventional and 100-ps time-resolved reflection high-energy electron diffraction. For the time-resolved studies, the surface is heated by 100-ps laser pulse while a synchronized electron beam probes the structure. When heated by 100-ps laser pulse, Ge(111)-c(2x8) and Ge(100)-(2x1) reconstruction is seen to overheat above the onset temperatures for the disordering under thermodynamic equilibrium. Slow heating shows that the adatoms in the Ge(111)-c(2x8) reconstruction state start to disorder at ∼510 K and are converted to a totally disordered adatom arrangement at 573 K. For heating with 100-ps laser pulses, time-resolved …

Melting And Resolidification Of A Substrate Caused By Molten Microdroplet Impact, Daniel Attinger, D. Poulikakos

Daniel Attinger

This paper describes the main features and results of a numerical investigation of molten microdroplet impact and solidification on a colder flat substrate of the same material that melts due to the energy input from the impacting molten material. The numerical model is based on the axisymmetric Lagrangian Finite-Element formulation of the Navier–Stokes, energy and material transport equations. The model accounts for a host of complex thermofluidic phenomena, exemplified by surface tension effects and heat transfer with solidification in a severely deforming domain. The dependence of the molten volume on time is determined and discussed. The influence of the thermal …

Dopant Structural Distortions In High-Temperature Superconductors: An Active Or A Passive Role?, Daniel Haskel, Edward A. Stern, Fatih Dogan, Arnie R. Moodenbaugh

Materials Science and Engineering Faculty Research & Creative Works

The parent compounds of high-temperature superconductors, such as YBa2Cu3O6 and La2CuO4, are strongly interacting electron systems, rendering them insulators with Mott-Hubbard gaps of a few electronvolts. Charge carriers (holes) are introduced by chemical doping, causing an insulator-metal (IM) transition and, at low temperatures, superconductivity. the role of dopants is widely seen as limited to the introduction of holes into the CuO2 planes (i.e. occupying electronic states derived from Cu and O 2px,y atomic orbitals). Most theories of high-Tc superconductivity deal with pairing interactions between these planar holes. Local distortions around dopants are poorly understood, because of the experimental difficulty in …

Network Formalism For Modeling Functionally Gradient Piezoelectric Plates And Stacks And Simulations Of Rainbow Ceramic Actuators, Robert W. Schwartz, A. Ballato, John Ballato

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A simple network representation is given for a stack of thin, homogeneous piezoelectric plates, executing a single thickness mode of motion. All plates may differ in thickness and material properties, including dielectric loss, ohmic conductivity, and viscous loss. Each plate is driven by a thickness-directed electric field, and all stack elements are connected electrically in series. Functionally gradient single plates and composites are readily modeled by the network, to a desired precision, using a sequence of circuit elements representing stepwise variations in material properties and layer thicknesses. Simulations of RAINBOW (reduced and internally biased oxide wafer) ceramics are given.

Optical And Etching Studies Of Native Aluminum Oxide Layers For Use In Microcavity Photonic Devices, William L. Bernhard

Theses and Dissertations

Optical communication and computing systems are required to meet future information transfer and processing needs. Microcavity devices serve as an enabling technology to implement and integrate optoelectronic systems. It is important to understand the optical and mechanical properties of materials utilize within microcavity devices. Only then is it possible to accurately model and analyze structures. Microcavity structures incorporating a high aluminum content AlGaAs layers are designed, grown, processed, and measured. The processing of these devices includes the conversion of high aluminum-content AlGaAs layers to native aluminum oxide (AlO) layers through the process of thermal oxidation. This selective conversion of microcavity …

Numerical Study Of Optical Delay In Semiconductor Multilayer Distributed Bragg Reflector And Tunable Microcavity Structures, Michael I. K. Etan

Theses and Dissertations

The Air Force has a growing need for the greater bandwidth, speed, and flexibility offered by optical communication links. Future space systems and airborne platforms will most likely use optical signals for efficient power transmission and to minimize the possibility of spoofing and eavesdropping. Tunable optical delays play an important role in the implementation of free space optical communication links. The primary challenge in implementing these systems is the active maintenance of coherent wave fronts across the system's optical aperture. For space applications, this aperture may he hundreds of meters in diameter. Spatial segmentation of a large aperture into smaller …

Fatigue Response Of Thin Stiffened Aluminum Cracked Panels Repaired With Bonded Composite Patches, Jason B. Avram

Theses and Dissertations

This research investigated the fatigue response of precracked and patched 2024-T3 Aluminum panels with stiffeners. Patches were single-sided, unidirectional three ply boron/epoxy. Stiffeners were 2024-T3 aluminum and were riveted and bonded on. Disbonds were introduced into the repair bondline by inserting teflon strips. Three disbond configurations were investigated rack tip disbond (CTD) located at the edge of the patch in the path of crack propagation, full-width disbond (FWD) covering the entire crack, and end disbond (ED) located at each end of the patch and covering the full width. Each repaired panel was subjected to tension/tension cyclic fatigue with a maximum …

Photoluminescence Of Single Quantum Well Structures In Gallium Arsenide, Christian A. Bartholomew

Theses and Dissertations

The continued development of state-of the-art semiconductor technologies and devices by the United States Air Force and the Department of Defense requires accurate and efficient techniques to evaluate and model these new materials. Of particular interest to the Air Force are quantum well structures which can be used for small-scale laser sources in fly-by-light applications, as efficient infrared countermeasures to heat-seeking missiles, or as advanced seekers in optically guided missiles. This thesis provides the initial experimental procedures and data necessary to begin producing accurate yet robust models. Although carrier effective masses could not be evaluated using hot-electron photoluminescence, photoluminescence excitation …

The Applications Of Confocal Raman Micro-Spectroscopy For Study Of Practical Electrode Materials, Yang Y, Chu W, Nan J M, Chen X G, Lin Z G

Journal of Electrochemistry

Some recent research work about applications of confocal Raman micro spectroscopy for study of practical electrode materials carried out in our lab has been briefly introduced. The examples include study of electrochemical Li + intercalation process, characterization of surface oxide film on AB 5 type electrodes and passive film and pitting corrosion of Rebar electrodes.

Synthesis Of Limn_2o_(4-Δ) Cl_Δ Cathode Material By Like-Sol-Gel Methode, Zhao Yong Chen, Yi He, Xing Quan Liu, Zhi-Jie Li, Zuo-Long Yu

Journal of Electrochemistry

LiMn 2O 4 δ Cl δ was synthesized by like sol gel methode, with calculated LiOH.H 2O, Mn(No 3) 2.6H 2O and LiCl.H 2O, and made electrochemical test with these compounds as positive materials. Result demostrated that LiMn 2O 4 δ Cl δ cathode material has exellent stability and nearly no capacity loss after reaching stability.

How Can Direct Mthanol Fuel Cell Benefit From Carbonate Media, Lin Zhuang, Yang Wang, Jun Tao Lu

Journal of Electrochemistry

The kinetics of methanol oxidation and oxygen reduction in 0.5 mol/L K 2CO 3 were compared with those in 0.5 mol/L H 2SO 4. Experiments revealed that carbonate media could be more beneficial to direct methanol fuel cell(DMFC).Firstly, both electrode reactions show better performance in the carbonate than in the acid; secondly, materials other than noble metals become possible to be used as the anodic and cathodic catalysts;thirdly, the potential dectease caused by methanol crossover could be depressed by using metal oxide catalysts not stable in acid, such as MnO 2.

Two-Dimensional Surface Raman Imaging Of A Roughened Iron Electrode In Saline Water, Pei-Gen Cao, Jian Lin Yao, Jun Wei Zheng, Bin Ren, Ren-Ao Gu, Zhong Qun Tian

Journal of Electrochemistry

The analysis of the composite and distribution of iron oxide due to pit corrosion in saline solutions (3.4% NaCl) is of great importance. Many electrochemical methods, XPS, and other photoelectronic techniques have been applied to this domain. Surface?enhanced Raman scattering (SERS) spectroscopy can provide the vibrational information of surface species with high sensitivity and is very useful in the study of surface chemistry of iron. Notwithstanding, the application of SERS in iron corrosion is hampered for its SERS?inactivity. Efforts have been devoted to extend the use of SERS to the study of iron. Approaches include the deposition of particles or …

A Study On The Performance Of Matrix Prepared By Tape Cast And Its Molten Carbonate Fuel Cells (Mcfcs), Hua-Xin Lin, Bao Lian Yi, Li Zhou, Chang-Qing He, Lian Ying Kong, En Jun Zhang

Journal of Electrochemistry

The matrix prepared with γ LiAlO 2 powder and by tape cast displayed higher ability of preventing from gas cross over and lower ohmic polarization. The voltages of the stack (three cells,122 cm 2) stacked with the matrix were 2.02 and 1.78 V at 200 and 246 mA/cm 2, respectively, and the output power reached 53.4 W. The cell(28 cm 2) voltages were 0.85 and 0.75 V at 200 and 300 mA/cm 2, respectively,and the output power was about 6.6 W. Compensating the shrinkage of matrix in stacking cells promoted the enhancement of the MCFC performance.

Catalytic Effect Of Cl~- On Electrodeposition Of Binary Zinc Alloys With Iron Group Metals, Ren-He Yin, Zheng Hua Fang, Wei Min Cao, A.Zakaria A.Zakaria, Rong-Ming Zhou

Journal of Electrochemistry

Zinc iron group metal alloys were deposited under coulostatic (10C.cm -2 ) at 40 ℃ chloride baths. The deposited alloys were quantitatively analyzed by Atomic Absorption Spectrometry. The current efficiency, percent content and partial polarization curves were obtained by the results. The morphology of the deposits was observed by means of Scanning Electron Microscopy(SEM). We observe that the electrodeposition of zinc iron group metal alloys is one of the best known examples of anomalous codeposition. We found the catalytic effect of Cl - on the electrodeposition behavior of iron group metal. Overpotential of iron group metal droped abruptly at high …

Adsorption And Oxidation Of Ethanol On Nm-Pt/Gc Electrode Ii. Eqcm And In-Situ Ftir Spectroscopic Studies In Acid Media, Guo Liang Chen

Journal of Electrochemistry

The adsorption and oxidation of ethanol on nm?Pt/GC electrode in acid solutions containing 0.1 mol·L -1 H 2SO 4 +0.1 mol·L -1 CH 3CH 2OH was investigated by using cyclic voltammetry , EQCM and in?situ FTIR spectroscopy. The experimental results demonstrated that the oxidation of CH 3CH 2OH is closely relaed to solution acidity and oxygen species on electrode surface; CH 3CH 2OH was oxidized on nm?Pt/GC electrode in acidic media via a dual path reaction mechanism, i.e . CH 3CH 2OH may be oxidized into CO 2 through the dissociative adsorbate (CO) and the reactive intermediates that were determined …

The Photoelectrochemistry Of Tio_2-Polyaniline Composite Film, Huai Guo Huang, Zhi Xin Zheng, Jin Luo, Hong-Ping Zhang, Ling-Ling Wu, Zhong-Hua Lin

Journal of Electrochemistry

A TiO 2 and polyaniline (PANI) composite film was obtained by electrochemical methods. The SEM image of the composite film showed that the PANI film is almost completely covered with TiO 2. The spectra of photocurrent for the TiO 2 PANI composite film , which overlaps the TiO 2 film and PANI film, showed that the composite film is able to have higher conversion efficiency. The spectra of photocurrent for the TiO 2 PANI composite film were different from these of TiO 2 film photosensitized by PANI. The bandgap energy of TiO 2 film on partially oxidized PANI film was …

Adsorption Behavior Of Co At The Ultrathin Rh And Pt Film Electrodes, Yong Xie, Xiao Qin Li, Bin Ren, Zhong-Qun Tian

Journal of Electrochemistry

Pt group metals have been widely used in catalysis such as hydrogenation of organic compounds and the oxidation of carbon monoxide. The information about CO adsorption on the Pt group surfaces and the influence of other surface species, such as hydrogen and CO 2, will be greatly helpful to elucidate the adsorption behavior of CO on Pt group metal surfaces and get a deeper understanding of catalytic mechanisms of Pt group metals. Surface enhanced Raman spectroscopy (SERS) has been becoming an increasingly important means to characterize the electrochemical metal solution interface over the past two decades. Our laboratory has successfully …

In Situ Raman Spectroelectrochemical Characterization Of The Prussian Blue/Platinum Modified Electrode, Xiao-Wei Cao, Rong Wang, Gui Hua Wang, Zong Rang Zhang

Journal of Electrochemistry

Prussian Blue is known to be deposited electrochemically on the electrode surface, producing a dense redox active layer. Since the Prussian Blue modified electrode was first reported by Neff in 1978 [1] , different in situ spectroelectrochemical techniques have been widely used to investigate its electrochemical mechanism [2～4] . But no research work related to the in situ Raman spectroscopic studies on it has been reported. In this paper we try to characterize the nature of thin Prussian Blue films on platinum substrates with in situ Raman spectroelectrochemical technique. A Super LABRAM confocal microscopic Raman spectrometer (Dilor) with a He?Ne …

Deposition Of Tantalum On Steel By Sputtering, Bhavin Shah

Theses

Recent interest in tantalum deposition comes from two different applications. One is in microelectronics where thin tantalum films (< 1 µm) are used as diffusion barrier layers for copper interconnects. The other involves its application as a material for corrosion and wear resistant coating on surfaces that are subjected to high stresses and harsh chemical and erosive environments.

This thesis is a part of the investigation done at the Ion Beam and Thin Film Research Laboratory at NJIT to study the deposition conditions and properties of tantalum thin films. It includes the design and construction of Planar D.C. Magnetron Sputtering System and Cylindrical D.C. Magnetron Sputtering System for deposition on the planar and cylindrical surfaces of steel, respectively. The electrical characteristics of the cylindrical system were tested in a range of pressures and conditions for initiation and maintaining of …

Method And Apparatus For Adaptive Process Control Of Critical Dimensions During Spin Coating Process, Richard N. Savage, Emir Gurer

Materials Engineering

A spin coating process for controlling the mean thickness of photoresist on the surface of a semiconductor wafer. The wafer surface has a central axis normal to the surface. The process comprises the steps of applying the solution to the wafer surface and spinning the wafer about the central axis at a spindle speed until the solution has dried. The spindle speed is a function of the desired mean thickness of the photoresist, the barometric pressure and the relative humidity. The spindle speed is determined from a statistical model described by the equation: MT=A+BxRH+CxBP+D/SS^1/2 wherein: MT is mean thickness …

Research Experiences For Undergraduates: Advanced Engineered Wood Composites, Eric N. Landis, Habib J. Dagher

University of Maine Office of Research Administration: Grant Reports

The aim of this program is interdisciplinary research experience for undergraduate science and engineering students. The focal point is the development of the next generation of engineered wood composites for construction applications. The disciplines involved include structural engineering, mechanics, composite materials, and wood science. The educational paradigm will be one of combining hands-on laboratory work with training in fundamental science and engineering principles. Previous experience with REU sites indicates that many students become interested in graduate research when they are able to see the fruits of their work used in some application. Thus the basis of this REU site is …

Texture, Microstructure And Formability Of Aluminum Alloys, Xiang-Ming Cheng

University of Kentucky Doctoral Dissertations

Texture, microstructure and formability were studied in Direct Chill Cast (DC) and Strip Cast (SC) aluminum alloys with regard to crystallographic anisotropy, the Portevin-Le Chatelier effect and aging softening behavior. It was found that material properties change greatly with manufacturing processes (DC vs. SC) and chemical composition (3xxx vs. 5 xxx alloys). DC cast hot band materials are usually fully recrystallized and have strong softening textures while SC hot band materials have a rolling structure with strong deformation textures. Softening textures cause 90 earing while deformation textures result in 45 earing after deep drawing. During cold rolling, 90 earing in …

Magnetic Nanoparticles And Nanoparticle Assemblies From Metallorganic Precursors, Suresh Pillai, Yurri Gunko, David Mcinerney

Articles

No abstract provided.

Unbiased Density Functional Solutions Of Freezing In Binary Mixtures Of Hard Or Soft Spheres, M. Valera, R. F. Bielby, F. J. Pinksi, Duane D. Johnson

Duane D. Johnson

various size ratios, σ2/σ1, using density functional theory. The Grand Potential is minimized using an unbiased, discrete, real-space mesh that does not constrain the shape of the density, and, in many cases, leads to solutions qualitatively different from those using Gaussians and plane-waves. Besides the usual face-centered-cubic solid-solution phase for σ2/σ1≈1.0, we find a sublattice-melt phase for σ2/σ1=0.85–0.5 (where the small-sphere density is nonlocalized and multi-peaked) and the NaCl phase for σ2/σ1=0.45–0.35 (when the small-sphere density again sharpens). For a range of size ratios of soft sphere mixtures, we could not find stable nonuniform solutions. Preliminary calculations within a Modified-Weighted …

Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase I, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells and buffered chemical polishing produce good performance. The objective of the proposed research is to maximize the performance of the niobium cavities through studying multipacting, studying the effect of chemical etching on the surface roughness, and redesigning the cavities.

The US Congress has recently authorized exploring an alternative way to deal with spent nuclear fuel: Accelerator Transmuting of Waste (ATW). In this approach, a particle accelerator produces protons that react with …