| Growth of Gallium Nitride Nanorods and Their Coalescence Overgrowth |
07 Sep 2012 |
24 pages |
| Authors:
Chih-Chung Yang; NATIONAL TAIWAN UNIV TAIPEI
|
 | With the nano-imprint lithography and the pulsed growth mode of metalorganic chemical vapor deposition, a regularly-patterned, c-axis nitride nanorod (NR) array of quite uniform geometry with simultaneous depositions of top-face, c-plane disc-like and sidewall, m-plane core-shell InGaN/GaN quantum well (QW) structures is formed. The differences of geometry and composition between these two groups of QW are studied with scanning electron microscopy, cathodoluminescence, and transmission electron microscopy (TEM). In particular, the ... |
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| Dissolution Rate of Propellant Energetics from Nitrocellulose Matrices |
Sep 2012 |
131 pages |
| Authors:
Susan Taylor; Katerina Dontsova; Susan Bigl; Colleen Richardson; James Lever; Jonathan Pitt; John P Bradley; Marianne Walsh; Jiri Simunek; ENGINEER RESEARCH AND DEVELOPMENT CENTER HANOVER NH COLD REGIONS RESEARCH AND ENGINEERING LAB
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| During firing, propellant residues are scattered onto the soil surface where their energetic compounds can be dissolved by precipitation. The residues, like the unfired propellants, are composed of nitrocellulose imbibed with either 2,4-DNT (single-base), nitroglycerin (NG) (double-base) or NG and nitroguanidine (NQ) (triple-base). Although nitrocellulose is insoluble, 2,4-DNT, NG, and NQ are soluble; and 2,4-DNT and NG are also toxic. Consequently, data on how quickly 2,4-DNT, NG, and NQ are ... |
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| Carbon-Coated Current Collectors for High-Power Li-Ion Secondary Batteries |
29 Aug 2012 |
10 pages |
| Authors:
Nae-Lih Wu; NATIONAL TAIWAN UNIV TAIPEI
|
| The ultimate goal of this project is to develop a viable C-coating process of the current collector to improve the overall power performance of the electrode of Li-ion batteries. During this period, study was focused onto the development of a low-temperature chemical vapor deposition (PA-CVD) process for C deposition. The PA-CVD vacuum chamber was set-up. The researchers completed the investigation of the effects of the processing parameters; the characteristics of ... |
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| Deformation Mechanisms and High Strain Rate Properties of Magnesium (Mg) and Mg Alloys |
Aug 2012 |
26 pages |
| Authors:
Bin Li; Logan Shannahan; Evan Ma; Kaliatt T Ramesh; Suveen Mathaudhu; Robert J Dowding; James W McCauley; JOHNS HOPKINS UNIV BALTIMORE MD
|
| This report summarizes research at the Johns Hopkins University Center for Advanced Metallic and Ceramic Systems on lightweight magnesium (Mg) and Mg alloys, under the sponsorship of the U.S. Army Research Laboratory (ARL) Materials Center of Excellence (MCOE) during 2007-2010. In collaboration with ARL, extensive studies have been conducted on the fundamental deformation mechanisms of pure Mg and the mechanical properties at high strain rate of ultrafine-grained Mg alloys. Atomistic ... |
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| A Rationale for Deformation Twinning in Nanocrystalline Magnesium and Magnesium AZ80 Alloy |
Jul 2012 |
8 pages |
| Authors:
Suveen N Mathaudhu; Weizong Xu; Baolong Zheng; Yuntian T Zhu; Enrique Lavernia; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIR/ WEAPONS MATERIALS DIV
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| Recent reports have shown that the generation of nanotwins in nanostructured grains can further enhance both the strength and ductility of fcc alloys; in such alloys, twinning can be far more prominent in nanoscale grains than for their coarse-grained counterparts where deformation twinning rarely occurs. Mg presents a more perplexing challenge, as the opposite phenomena occurs; twinning is a prevalent deformation mode for coarse-grained materials, but has been observed to ... |
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| In-Situ Neutron Diffraction Study of Aging of a Mg-Y-Nd-Zr Alloy (WE43): Effects of Precipitation on Individual Deformation Mechanisms |
Jul 2012 |
9 pages |
| Authors:
S R Agnew; III Polesak F J; B Clausen; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| There is an outstanding question regarding why the age hardening response of Mg alloys is not nearly as good as many competing Al alloys. It has recently been proposed that the effect is due to precipitate geometry, since most commercial Mg alloys form either basal plate-shaped precipitates (e.g. AZ alloys) or c-axis aligned rod-shaped precipitates (e.g. ZK alloys) [1], and these are among the least effective precipitate shapes to obstruct ... |
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| In Situ Raman Spectroscopy of the Nanodiamond-to-Carbon Onion Transformation During Thermal Annealing of Detonation Nanodiamond Powder |
Jun 2012 |
75 pages |
| Authors:
Jonathan E Cebik; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| In this study, in situ Raman spectroscopy is utilized to investigate the onset of nanodiamond (ND) graphitization, the conversion of diamond (sp3) to graphitic (sp2) carbon, and the subsequent formation of carbon onions. Although the ND-to-carbon onion transformation through thermal annealing of ND in vacuum or inert atmosphere at high temperatures is a well-known phenomenon, the kinetics of the transformation and related structural changes in the nanocrystals are yet not ... |
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| Microstructure Analysis of Boron Nanotubes |
May 2012 |
13 pages |
| Authors:
Tapan Chatterjee; Stacey Kerwien; Elias Jelis; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ ENERGETICS WARHEADS AND MANUFACTURING TECHNOLOGY DIRECTORATE
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| Transmission electron microscopy and electron diffraction technique revealed boron nitride nanotube and nanoparticles in thin film boron nitride prepared by CVD method. Electron micrographs show single walled nanotubes containing these nonoparticles. The electron diffraction pattern confirms this boron nitride has a hexagonal crystal structure. |
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| Microstructure Analyses of Detonation Diamond Nanoparticles |
May 2012 |
15 pages |
| Authors:
Tapan Chatterjee; Stacey Kerwien; Elias Jelis; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ ENERGETICS WARHEADS AND MANUFACTURING TECHNOLOGY DIRECTORATE
|
| Transmission electron microscopy and electron diffraction technique revealed detonation diamond nanoparticles approximately 5.to 6 nm in diameter. The scanning electron microscope pictures showed the octahedral shape and lustrous faces of this bulk nanomaterial. The EDAX analysis from this perfectly well purified powder material showed a single C peak. The electron diffraction and x-ray diffraction patterns confirmed these nanoparticles have octahedral crystal habit and cubic crystal system. |
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| The Effect of Twins on the Mechanical Behavior of Boron Carbide |
May 2012 |
10 pages |
| Authors:
Tomoko Sano; Charles L Randow; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The microstructure and mechanical properties of boron carbide (B4C) samples processed by slip casting were compared with those processed by the conventional hot-pressing technique. Although the quasi-static and dynamic mechanical experiments showed comparable results between the slip-cast and hot-pressed B4C, scanning electron microscopy and electron backscattered diffraction of the B4C samples revealed significant differences in the microstructure. A notable difference was the numerous growth twins in the slip-cast samples. The ... |
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| Microstructural Characteristics of High Rate Plastic Deformation in Elektron (trademark) WE43 Magnesium Alloy |
Apr 2012 |
12 pages |
| Authors:
Joseph Hamilton; Sarah T Brennan; Yongho Sohn; Bruce Davis; Rick DeLorme; Kyu Cho; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| High strain rate deformation of WE43 magnesium alloy was carried out by high velocity impacts, and the characteristics and mechanisms of microstructural damage were examined. Six samples were subjected to a variety of high velocity impact loadings that resulted in both partial and full damage. Optical, scanning and transmission electron microscopy analyses were performed in order to identify regions of shear localization. These regions were used to map, both quantitatively ... |
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| Northwest Manufacturing Initiative |
27 Mar 2012 |
316 pages |
| Authors:
J R Evans; Ellen A Fuller; Mary Chalkiopoulos; Brice Barrett; William E Wood; Rajarsekar Talla; Jyothi Kadali; Richard Nordstrom; Thomas Quale; Jesse Aronson; ORGANIZATION FOR ECONOMIC INITIATIVES INC SPRINGFIELD OR
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| The Northwest Manufacturing lnititaive, through its partner organizations, has conducted research into Northwest defense industrial base capability gaps, primarily through manufacturing workforce assessment and targeted training, including Lean Manufacturing, Leadership and Supervisory Training, and Project Management, resulting in increased and retained sales and job creation. A database to optimize manufacturing buyer/supplier connections, called the NW Connectory, was also developed. In addition, we sought to address defense systems engineering gaps through ... |
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| Synthesis and Characterization of Aluminum-Carbon Nanotube Composite by Cryogenic Milling |
Mar 2012 |
75 pages |
| Authors:
Brent A Bottolfson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Cryogenic milling was studied for the ex situ strengthening of aluminum (Al) with carbon nanotubes (CNT). Characterization of mechanically alloyed Al-CNT powders was conducted in preparation for bulk powder processing to be used in cold spray. Al-CNT metal matrix composite powders with 5 wt.% and 10 wt.% CNT were synthesized by cryogenic milling of the blended component powders. Stearic acid was used as a process control agent to minimize agglomeration ... |
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| Assessment of Chemical Solution Synthesis and Properties of Gd2Zr2O7 Thin Films as Buffer Layers for Second-Generation High-Temperature Superconductor Wires (Postprint) |
Feb 2012 |
11 pages |
| Authors:
T Aytug; M Paranthaman; K J Leonard; H Y Zhai; M S Bhuiyan; E A Payzant; A Goyal; S Sathyamurthy; D B Beach; P M Martin; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| Chemical solution processing of Gd2Zr2O7 (GZO) thin films via sol-gel and metalorganic decomposition (MOD) precursor routes have been studied on textured Ni-based tape substrates. Even though films processed by both techniques showed similar property characteristics, the MOD-derived samples developed a high degree of texture alignment at significantly lower temperatures. Both precursor chemistries resulted in exceptionally dense, pore-free, and smooth microstructures, reflected in the cross-sectional and plan-view high-resolution scanning and transmission ... |
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| SM and ND Substiturions in YBCO Films Produced through Metal Organic Deposition (Postprint) |
Feb 2012 |
8 pages |
| Authors:
B C Harrison; J Carpenter; and P N Barnes P Klenk; H Fang; C V Varanasi; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Epitaxial YBa2Cu3O7-x (YBCO) films were produced on non-buffered (100) single crystal LaAlO3 using the metal organic deposition (MOD) method with fluorinated metal acetates. In an effort to enhance the in-field performance of the films, Sm and Nd acetates were fractionally substituted for Y acetate in a series of precursor solutions to incorporate an array of nanoscale flux pinning centers in the post-annealed films. From measurements taken in the non-optimized films ... |
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| Effect of Nickel Content on the Crystallization Behavior in Nanocrystalline (CO1-XNIX)88ZR7B4CU1 Soft Magnetic Alloys |
Jan 2012 |
61 pages |
| Authors:
Billy C Hornbuckle; Gregory B Thompson; Nitin Chopra; Gary Mankey; ALABAMA UNIV TUSCALOOSA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
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| A series of (Co1-xNix)88Zr7B4Cu1 soft magnetic alloys, where X was varied from 0 to 1, were fabricated by a melt spinning process into thin ribbons of the material. This process was followed by an isothermal anneal to produce a nanocomposite alloy, i.e. nanocrystalline grains in a residual amorphous matrix. The alloy series was designed to investigate crystallization kinetics and limits to the compositional regime where a nanocomposite could be formed. ... |
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| Recombinant Reflectin-Based Optical Materials |
Jan 2012 |
13 pages |
| Authors:
Guokui Qin; Patrick B Dennis; Yuji Zhang; Xiao Hu; Jason E Bressner; Zhongyuan Sun; Wendy J Crookes-Goodson; Rajesh R Naik; Fiorenzo G Omenetto; David L Kaplan; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| Reflectins are a unique group of structural proteins involved in dynamic optical systems in cephalopods that modulate incident light or bioluminescence. We describe cloning structural characterization, and optical properties of a reflectinbased domain, refCBA, from reflectin 1a of Hawaiian bobtail squid, Euprymna scolopes. Thin films created from the recombinant protein refCBA display interesting optical features when the recombinant protein is appropriately organized. RefCBA was cloned and expressed as a soluble ... |
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| Synthesis and Characterization of Aluminum-Nanodiamond Composite Powders by High Energy Ball Milling |
Dec 2011 |
73 pages |
| Authors:
Brian D Sneed; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| High-energy ball milling was studied for the ex situ strengthening of aluminum (Al) with nanodiamond (ND). Al-ND metal matrix composite powders with 5 wt% and 10 wt% nanodiamond were synthesized by high-energy ball milling of the blended component powders. Stearic acid was used as a process control agent to minimize agglomeration of the powders upon milling. A uniform distribution of the ND reinforcement was successfully obtained after milling the powders ... |
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| Physical and Mechanical Characterization of a Nano Carbon Infused Aluminum-Matrix Composite |
Oct 2011 |
16 pages |
| Authors:
Lloyd Brown; Peter Joyce; DAVID FORREST; Jennifer Wolk; NAVAL ACADEMY ANNAPOLIS MD DEPT OF MECHANICAL ENGINEERING
|
| A nanocarbon-infused aluminum-matrix composite, termed covetic, has been developed by Third Millennium Metals, LLC, and we have evaluated the enhanced performance prospects for strength and electrical conductivity. This paper examines the effects of the nanoscale carbon on the physical, electrical and mechanical properties of the metal-matrix composite based on microscopy, hardness, quasi-static tensile strength, high strain-rate compression strength and electrical conductivity measurements. In the as-extruded condition (warm worked at 400 ... |
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| Development of Thin Films as Potential Structural Cathodes to Enable Multifunctional Energy-Storage Structural Composite Batteries for the U.S. Army's Future Force |
Sep 2011 |
18 pages |
| Authors:
Eric Ngo; James Snyder; Clifford Hubbard; S G Hirsch; Conrad Xu; Robert Carter; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Well formed films of pure LiMn2O4 were obtained by spin-coating stoichiometric amounts of manganese acetate Mn(CH3COOH)2.4H2O and lithium acetate Li(CH3COOH)2.4H2O dissolved in a mixture of acetic acid (CH3COOH) and 2-methoxyethanol (H3COCH2CH2OH) onto platinum coated silicon substrates. Several coats of solution were applied to reach the desired film thickness of approximately 200nm and then annealed at various temperatures ranging from 400 C to 800 C to crystallize the films into a ... |
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| Synthesis of Gold and Silver Nanoparticles and Characterization of Structural, Optical, and Electronic Properties |
Sep 2011 |
22 pages |
| Authors:
Eric N Lee; Mark H Griep; Shashi P Karna; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Metallic nanoparticles, most notably gold and silver, portray multiple structural, optical, electronic, and photoelectric properties, all of which often vary with particle diameter. When synthesized as alloys, as compared to purely monometallic particles, changes in the synthesis procedure and conditions can yield entirely unique particles with variable absorbance levels, sizes, and emission intensities, and stronger characteristics much more suited for use in electronic applications. Through solution-phase synthesis and replacement-reaction synthesis, ... |
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| Visualizing Individual Nitrogen Dopants in Monolayer Graphene |
19 Aug 2011 |
7 pages |
| Authors:
Liuyan Zhao; Rui He; Kwang T Rim; Theanne Schiros; Keun S Kim; Hui Zhou; Christopher Gutierrez; S P Chockalingam; Carlos J Arguello; Lucia Palova; COLUMBIA UNIV NEW YORK DEPT OF PHYSICS
|
| In monolayer graphene, substitutional doping during growth can be used to alter its electronic properties. We used scanning tunneling microscopy, Raman spectroscopy, x-ray spectroscopy, and first principles calculations to characterize individual nitrogen dopants in monolayer graphene grown on a copper substrate. Individual nitrogen atoms were incorporated as graphitic dopants, and a fraction of the extra electron on each nitrogen atom was delocalized into the graphene lattice. The electronic structure of ... |
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| Microstructural Investigation and Evaluation of Mechanical Properties in Friction Stir Welded Joints |
Aug 2011 |
21 pages |
| Authors:
Brian Justusson; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| With involvement of the United States Military in various places in the world, increased improvements in personnel and vehicle protection are needed. Traditionally, armoring techniques have performed well against particular threats; however, a new threat has emerged from improvised explosive devices (IEDs), which has exposed the vulnerability of the undercarriage of the vehicle to explosions. Various solutions have been proposed to combat this problem, such as implementation of a unibody ... |
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| A New Class of Solid-Solid Phase Transformations Involving a Composition-Dependent Displacive Component (Preprint) |
Jul 2011 |
6 pages |
| Authors:
S Nag; A Devaraj; N Gupta; S G Srinivasan; R Banerjee; R Srinivasan; R E Williams; H L Fraser; G B Viswanathan; J S Tiley; S Banerjee; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| Solid-solid displacive, structural phase transformations typically undergo a discrete structural change from the parent to the product phase. Coupling electron microscopy, three-dimensional atom probe, and first-principles computations, we present the first direct evidence of a novel mechanism for a coupled diffusional-displacive transformation in an important class of titanium-molybdenum alloys wherein the displacive component in the product phase changes continuously, as a function of its composition. These results cannot be explained ... |
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| Dynamic Testing of Signal Transduction Deregulation During Breast Cancer Initiation |
Jul 2011 |
31 pages |
| Authors:
TUAN VO-DINH; Victoria Seewaldt; Yan Zhang; Jonathan P Scaffidi; Molly K Gregas; Benoit Lauly; Stephen De Vience; Anuj Dhawan; Hsinneng Wang; Hsiang-Kuo Yuan; DUKE UNIV DURHAM NC
|
| The goal of our study is to develop nanosensors to detect pre-cancerous changes in the breast and figure out which pre-cancerous breast changes have the highest chance of progressing to become invasive breast cancer. In particular, we are developing targeted nanobiosensors to test real-time protein phosphorylation signaling in live RPFNA cells. In this study, we have designed fiber-optic nanoprobes for optical detection in single living cells. The nanoprobes were fabricated ... |
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| Epitaxial Graphene Surface Preparation for Atomic Layer Deposition of Al2O3 |
JUN 2011 |
7 pages |
| Authors:
N. Y. Garces; V. D. Wheeler; J. K. Hite; G. G. Jernigan; J. L. Tedesco; Neeraj Nepal; Jr. Eddy C. R.; D. K. Gaskill; NAVAL RESEARCH LAB WASHINGTON DC
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| Atomic layer deposition was employed to deposit relatively thick ( 30 nm) aluminum oxide (Al2O3) using trimethylaluminum and triply-distilled H2O precursors onto epitaxial graphene grown on the Si-face of silicon carbide. Ex situ surface conditioning by a simple wet chemistry treatment was used to render the otherwise chemically inert graphene surface more amenable to dielectric deposition. The obtained films show excellent morphology and uniformity over large ( 64 mm2) areas ... |
|
| Microstructure Evolution during Friction Stir Welding of Mill-Annealed Ti-6Al-4V (Preprint) |
May 2011 |
46 pages |
| Authors:
A L Pilchak; J C Wiliams; W Tang; H Sahiner; A P Reynolds; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| In this study, mill-annealed Ti-6Al-4V plates were successfully friction stir welded over a wide range of processing parameters using a tungsten - 1%La2O3 tool. Two K-type thermocouples embedded in the tool indicated that approximately 25 pct. of the heat generated during welding was transferred out of the workpiece and into the tool. The thermocouple data, combined with observations of the microstructure, indicated that the stir zone of all welds exceeded ... |
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| Combustion Synthesis Reaction Behavior of Cold-Rolled Ni/Al and Ti/Al Multilayers |
Apr 2011 |
36 pages |
| Authors:
Laszlo J Kecskes; Xiaotun Qiu; Ranran Lin; Jesse H Graeter; Shengmin Guo; Jiaping Wang; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| A two- or three-stage combustion synthesis reaction process was observed in cold-rolled Ni/Al and Ti/Al multilayer foils. The phase evolution sequence from the two foil types was studied by differential scanning calorimetry (DSC). Several exothermic peaks were identified from the DSC thermograms. Subsequently, the foils were heated to each peak temperature to identify the reaction product associated with each peak. X-ray diffraction and scanning electron microscopy analyses were used to ... |
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| Imaging Surfaces and Nanostructures |
28 Feb 2011 |
3 pages |
| Authors:
Ahmed H Zewail; CALIFORNIA INST OF TECH PASADENA
|
| Publications of this research are reported in Science, JACS, JPC, ChemPhysChem, PNAS, Nano Lett., and PCCP. Developmentally, we have advanced ultrafast electron microscopy (and diffraction) to a new level. The electron pulses typically have an energy of 30 keV for diffraction and 100-200 keV for microscopy, corresponding to speeds of 33-70% of the speed of light. Recently, we introduced the concept of tilted optical pulses into diffraction and imaging techniques ... |
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| Transfer of CVD-Grown Monolayer Graphene onto Arbitrary Substrates |
Jan 2011 |
10 pages |
| Authors:
Ji W Suk; Alexander Kitt; Carl W Magnuson; Yufeng Hao; Samir Ahmed; Jinho An; Anna K Swan; Bennett B Goldberg; Rodney S Ruoff; TEXAS UNIV AT AUSTIN DEPT OF MECHANICAL ENGINEERING
|
| Reproducible dry and wet transfer techniques were developed to improve the transfer of large-area monolayer graphene grown on copper foils by chemical vapor deposition (CVD). The techniques reported here allow transfer onto three different classes of substrates substrates covered with shallow depressions, perforated substrates, and flat substrates. A novel dry transfer technique was used to make graphene-sealed microchambers without trapping liquid inside. The dry transfer technique utilizes a polydimethylsiloxane frame ... |
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| Reverse Gate Bias-Induced Degradation of AlGaN/GaN High Electron Mobility Transistors |
23 Sep 2010 |
5 pages |
| Authors:
Chih-Yang Chang; Travis Anderson; Jennifer Hite; Liu Lu; Chien-Fong Lo; Byung-Hwan Chu; D J Cheney; E A Douglas; B P Gila; F Ren; FLORIDA UNIV GAINESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| A threshold reverse bias of 21 V was observed leading to a sharp increase in the gate current of AlGaN/GaN high electron mobility transistors biased at low source-drain voltage (5 V). The gate current increases by one to two orders of magnitude at this bias, corresponding to an electric field strength around 1.8 MV cm 1. The gate current increased by roughly five orders of magnitude after step-stressing the gate ... |
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| Characterization and Cytotoxic Assessment of Ballistic Aerosol Particulates for Tungsten Alloy Penetrators into Steel Target Plates |
26 AUG 2010 |
21 pages |
| Authors:
Brenda I. Machado; Lawrence E. Murr; Raquel M. Suro; Sara M. Gaytan; Diana A. Ramirez; Kristine M. Garza; Brian E. Schuster; TEXAS UNIV AT EL PASO DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
|
| The nature and constituents of ballistic aerosol created by kinetic energy penetrator rods of tungsten heavy alloys (W-Fe-Ni and W-Fe-Co) perforating steel target plates was characterized by scanning and transmission electron microscopy. These aerosol regimes, which can occur in closed, armored military vehicle penetration, are of concern for potential health effects, especially as a consequence of being inhaled. In a controlled volume containing 10 equispaced steel target plates, particulates were ... |
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| Structural Differences in Mg-doped InN - Indication of Polytypism |
Jan 2010 |
5 pages |
| Authors:
Z Liliental-Weber; M E Hawkridge; X Wang; A Yoshikawa; CALIFORNIA UNIV BERKELEY LAWRENCE BERKELEY LAB
|
| Transmission Electron Microscopy shows that the InN samples doped with either increasing or constant Mg concentration follow a cation or anion substrate polarity. In-polar samples change growth polarity when the Mg concentration is 1019 cm-3. N-polar samples have much higher density of planar defects than In-polar samples and their presence leads to a decrease in dislocation density. In the N-polar samples equally spaced planar defects are observed for Mg concentration ... |
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| Synthesis of Nitrogen-Doped Graphene Films for Lithium Battery Application |
Jan 2010 |
7 pages |
| Authors:
Arava L Reddy; Anchal Srivastava; Sanketh R Gowda; Hemtej Gullapalli; Madan Dubey; Pulickel M Ajayan; RICE UNIV HOUSTON TX DEPT OF MECHANICAL ENGINEERING AND MATERIALS SCIENCE
|
| We demonstrate a controlled growth of nitrogen-doped graphene layers by liquid precursor based chemical vapor deposition (CVD) technique. Nitrogen-doped graphene was grown directly on Cu current collectors and studied for its reversible Li-ion intercalation properties. Reversible discharge capacity of N-doped graphene is almost double compared to pristine graphene due to the large number of surface defects induced due to N-doping. All the graphene films were characterized by Raman spectroscopy, transmission ... |
|
| GaN Nanowire Functionalized with Atomic Layer Deposition Techniques for Enhanced Immobilization of Biomolecules |
Jan 2010 |
11 pages |
| Authors:
D J Guo; A I Abdulagatov; D M Rourke; K A Bertness; S M George; Y C Lee; W Tan; COLORADO UNIV AT BOULDER DEPT OF CHEMISTRY AND BIOCHEMISTRY
|
| We report the use of atomic layer deposition (ALD) coating as a nanobiosensor functionalization strategy for enhanced surface immobilization that may enable higher detection sensitivity. Three kinds of ALD coating films, Al2O3, TiO2, and SiO2, were grown on the gallium nitride nanowire (GaN NW) surfaces and characterized with high-resolution transmission electron microscopy (HRTEM) and vacuum Fourier transform infrared spectroscopy (FTIR). Results from HRTEM showed that the thicknesses of ALD-Al2O3, ALD-TiO2 ... |
|
| Compressed Sensing and Electron Microscopy |
Jan 2010 |
54 pages |
| Authors:
Peter Binev; Wolfgang Dahmen; Ronald DeVore; Philipp Lamby; Daniel Savu; Robert Sharpley; SOUTH CAROLINA UNIV COLUMBIA
|
| Compressed Sensing (CS) is a relatively new approach to signal acquisition which has as its goal to minimize the number of measurements needed of the signal in order to guarantee that it is captured to a prescribed accuracy. It is natural to inquire whether this new subject has a role to play in Electron Microscopy (EM). In this paper, we shall describe the foundations of Compressed Sensing and then examine ... |
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| Description and Comparison of Morphological Structures of the Eggs of Anopheles Hyrcanus Group and Related Species (Diptera: Culicidae) from the Republic of Korea |
20 Oct 2009 |
19 pages |
| Authors:
Leopoldo M Rueda; Tracy L Brown; Heung-Chul Kim; Terry A Klein; Amporn Thongkukiatkul; Van Sherwood; WALTER REED ARMY INST OF RESEARCH SILVER SPRING MD DEPT OF ENTOMOLOGY
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| The eggs of six Anopheles Hyrcanus Group (An. sinensis Wiedemann, An. kleini Rueda, An. belenrae Rueda, An. pullus M. Yamada, An. lesteri Baisas and Hu, An. sineroides S. Yamada) and related species (An. koreicus S. Yamada and Watanabe, An. lindesayi japonicus S. Yamada), were described from scanning electron micrographs of specimens collected from different localities of the Republic of Korea. Morphometric measurements of egg samples of the eight species were ... |
|
| Super-Resolution Image Reconstruction by Nonlocal Means Applied to High-Angle Annular Darkfield Scanning Transmission Electron Microscopy (HAADF-STEM) |
06 Oct 2009 |
14 pages |
| Authors:
Peter Binev; Francisco Blanco-Silva; Douglas Blom; Wolfgang Dahmen; Robert Sharpley; Tom Vogt; SOUTH CAROLINA UNIV COLUMBIA
|
| We outline a new systematic approach to extracting high resolution information from HAADF-STEM images which will be beneficial to the characterization of beam sensitive materials. The idea is to treat several, possibly many low electron dose images with specially adapted digital image processing concepts at a minimum allowable spatial resolution. Our goal is to keep the overall cumulative electron dose as low as possible while still staying close to an ... |
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| Electron Microscopy of Tungsten Disulphide Inorganic Nanomaterials |
Sep-2009 |
13 pages |
| Authors:
Stacey Kerwien; Tapan Chatterjee; Elias Jelis; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ
|
| Transmission and scanning electron microscopy studies of tungsten disulphide nanomaterials revealed nanotubes and onion-like structures. An electron diffraction pattern confirmed the lattice image of this nanotube. The tungsten disulphide nanomaterials exhibiting this kind of nanotubes will be useful as solid lubricant materials. |
|
| Structural and Mechanistic Analyses of TSC1/2 and Rheb 1/2-Mediated Regulation of the mTORC Pathway |
Jul-2009 |
21 pages |
| Authors:
David M Sabatini; WHITEHEAD INST FOR BIOMEDICAL RESEARCH CAMBRIDGE MA
|
| The mammalian target of rapamycin complex 1 (mTORC1) formed by mTOR, Raptor, mLST8 and PRAS40 is a principal regulator of cell growth in response to the nutrient and energy status of the cell, and its deregulation has recently emerged as a key driver in human cancers. Here, we present three-dimensional structures of the intact complex, as well as free Raptor, at nominal resolutions of 26 and 30 , as determined ... |
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| Viper Plague Project |
Jul-2009 |
50 pages |
| Authors:
Isaac Rosas; Yvette Gonzalez; Johnathan L de los Kiel; Amy Santos; Carrie Andrews; Jill E Parker; CONCEPTUAL MINDWORKS INC SAN ANTONIO TX
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| The term Viper Plague was coined for a lethal disease state seen in snakes belonging to a private herpetological collection infested with ticks (Kiel et al, 2006). Viper Plague presented signs and symptoms in the reptiles that were characteristically nearly identical to the Erhlichia disease Heartwater, also known as Cowdriosis, a highly lethal livestock disease (a USDA non-overlap Select Agent pathogen, exotic). It was revealed that some of the snakes ... |
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| Atomic Layer Deposition on Gram Quantities of Multi-Walled Carbon Nanotubes |
03 Jun 2009 |
12 pages |
| Authors:
Andrew S Cavanaugh; Christopher A Wilson; Alan W Weimer; Steven M George; COLORADO UNIV AT BOULDER DEPT OF CHEMISTRY AND BIOCHEMISTRY
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| Atomic layer deposition (ALD) was employed to grow coaxial thin films of Al2O3 and Al2O3/W bilayers on multi-walled carbon nanotubes (MWCNTs). Although the MWCNTs have an extremely high surface area, a rotary ALD reactor was successfully employed to perform ALD on gram quantities of MWCNTs. The uncoated and ALD-coated MWCNTs were characterized with transmission electron microscopy and x-ray photoelectron spectroscopy. Al2O3 ALD on untreated MWCNTs was characterized by nucleation difficulties ... |
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| Development of Methods for the Quantification of Microstructural Features in Alpha+Beta Processed Alpha/Beta Titanium Alloys (Preprint) |
Mar-2009 |
22 pages |
| Authors:
J Tiley; H L Fraser; P C Collins; B Welk; T Searles; J C Russ; NORTH TEXAS STATE UNIV DENTON
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| A set of stereological procedures has been developed for the rigorous quantification of microstructural features resolvable using scanning electron microscopy in alpha+beta processed alpha/beta titanium alloys. This paper identifies the four microstructural features that most likely influence the mechanical properties in alpha+beta processed titanium alloy, including: the size of the equiaxed alpha, the volume fraction of the equiaxed alpha, the volume fraction of total alpha, and the thickness of the ... |
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| Development of Carbon/Carbon Composites with Through-Thickness Carbon Nanotubes for Thermal and Structural Applications |
Dec-2008 |
34 pages |
| Authors:
Zhiyong (Richard) Liang; Chuck Zhang; FAMU/FSU COLL OF ENGINEERING TALLAHASSEE FL DEPT OF INDUSTRIAL ENGINEERING
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| Carbon/carbon composites offer lightweight thermal protection capable of producing excellent thermal materials. To further improve the thermal conductivity along the thickness direction and the interlaminar shear strength, we studied and demonstrated a novel method to stitch carbon nanotube yarns along the through-thickness direction of carbon fiber two-dimensional precursor felt perform to make novel 3D reinforced carbon/carbon (C/C) composites. By stitching nanotube yarns, high strength and thermal conductive CNTs were incorporated ... |
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| Propulsion and Power Rapid Response R&D Support Delivery Order 0041: Power Dense Solid Oxide Fuel Cell Systems: High Performance, High Power Density Solid Oxide Fuel Cells - Materials and Load Control |
Dec-2008 |
52 pages |
| Authors:
Stephen W Sofie; Steven R Shaw; Peter A Lindahl; Lee H Spangler; MONTANA STATE UNIV BOZEMAN
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| High Performance, High Power Density Solid Oxide Fuel Cells: Materials: The current geometry and materials set of the state-of-the-art anode supported cell (ASC) yields several deficiencies that limit the performance and robustness of the cell/stack under demanding aero based operational requirements. These deficiencies are embodied in poor gas transport through mechanically strong anodes, the limited use of cerium oxide in the anode due to unfavorable thermal expansion, and the poor ... |
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| Lifetime of Sodium Beta-Alumina Membranes in Molten Sodium Hydroxide |
JUL 2008 |
18 pages |
| Authors:
Gudmundur Gunnarsson; ICELAND UNIV REYKJAVIK TECHNOLOGICAL INST OF ICELAND
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| Sodium metal can be made by electrolysis of molten sodium hydroxide in sodium Beta-alumina membrane electrolysis cells. However, there are some uncertainties about the lifetime of the sodium Beta"-alumina membranes in contact with molten sodium hydroxide. The main objective of this project is to address these uncertainties and to study if the properties of the membrane degrade upon long term contact with molten sodium hydroxide. Electrolysis cells were designed, but ... |
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| Two Phase Monazite/Xenotime 30LaPO4-70YPO4 Coating of Ceramic Fiber Tows (Postprint) |
APR 2008 |
11 pages |
| Authors:
E. E. Boakye; R. S. Hay; P. Mogilevsky; M. K. Cinibulk; UES INC DAYTON OH
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| Equiaxed yttrium-lanthanum phosphate nanoparticles (Y(0.7),La(0.3))PO4(dot)0.7H2O were made and used to continuously coat Nextel(Trademark) 720 fiber tows. The particles were precipitated from a mixture of yttrium and lanthanum citrate chelate and phosphoric acid (H3PO4), and characterized with differential thermal analysis and thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The coated fibers were heat treated at 1000-1300 deg C for 1, 10, and 100 h. Coating grain growth ... |
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| Electrophysiological and Ultrastructural Characterization of Neuromuscular Junctions in Diaphragm Muscle of Acetylcholinesterase Knockout Mice |
Apr-2008 |
23 pages |
| Authors:
Michael Adler; Tracey A Hamilton; Oksana Lockridge; Ellen Duysen; Sharad S Deshpande; ARMY MEDICAL RESEARCH INST OF CHEMICAL DEFENSE ABERDEEN PROVING GROUND MD
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| 14. ABSTRACT Electrophysiological and ultrastructural studies were performed on phrenic nerve-hemidiaphragm preparations isolated from wild-type (AChE +/+) and acetylcholinesterase knockout (AChE -/-) mice to determine the compensatory mechanism manifested by the neuromuscular junction to excess acetylcholine (ACh). Nerve-elicited muscle contractions, miniature endplate potentials (MEPPs) and evoked endplate potentials (EPPs) were recorded by conventional electrophysiological techniques from phrenic nerve-hemidiaphragm preparations isolated from 1.5- to 2-month-old mice. Tension measurements from AChE -/- ... |
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| Advanced Cathodes for Next Generation Electric Propulsion Technology |
01-Mar-2008 |
174 pages |
| Authors:
Dustin J Warner; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| The research presented here investigated the feasibility of a 6.4 mm Lanthanum Hexaboride (LaB6) and Cerium Hexaboride (CeB6) hollow cathode for low power electric propulsion applications (100-300W). Two orifice geometries, one anode configuration, several anode and keeper currents, and a range of flow rates were tested for the LaB6 cathode. The CeB6 cathode underwent the same tests, with the exception of the second orifice geometry due to time constraints. The ... |
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| Nanoscale Characterization of Elemental Partitioning Between Gamma and Gamma Prime Phases in Rene 88DT Nickel Base Superalloy (Preprint) |
Feb-2008 |
35 pages |
| Authors:
J Tiley; J Y Hwang; R Banerjee; R Srinivasan; G B Viswanathan; H L Fraser; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| The chemical partitioning of alloying elements between the disordered y and ordered y' phases in the nickel base superalloy Rene 88DT, has been characterized in detail using three dimensional atom probe tomography (3DAP) coupled with energy-filtered transmission electron microscopy studies. After a homogenization treatment followed by a water quench, it is observed that the morphology of the y' precipitates, reduces with increasing aging time, while the compositional gradient across the ... |
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ELECTRON MICROSCOPY
