| Effect of Environmental Parameters on the Biocidal Performance of Iodine-Treated Filters |
JAN 2008 |
85 pages |
| Authors:
Chang-Yu Wu; Jin-Hwa Lee; Lindsey Reiemenschneider; Alexandros D. Theodore; FLORIDA UNIV GAINESVILLE DEPT OF ENVIRONMENTAL ENGINEERING SCIENCES
|
 | Iodine-treated filter media were challenged at a face velocity of 14.2 cm/s by Bacillus subtilis spores and MS2 bacteriophage aerosols generated from a Collison nebulizer. The novel medium displayed excellent viable removal efficiency (VRE) for bacterial spores with a negligible pressure drop in various environmental conditions, suggesting an alternative to HEPA filters for the removal of bacterial spore aerosols. Different filter media tested for viral aerosols showed VRE >90% but ... |
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| Numerical Implementation of Surface Catalysis, Reaction, and Sublimation |
01 JUL 2007 |
21 pages |
| Authors:
Chul Park; KOREA ADVANCED INST OF SCIENCE AND TECHNOLOGY DAEJEON (KOREA)
|
| This lecture consists of three parts: 1) quantification of rates of gas-surface interaction, 2) formulation of gas-surface balance conditions, and 3) survey of the gas-surface interaction problems in the entry flights of various planets. The first part reviews the role of surface rates and flow parameters in Goulard's theory, the catalytic rates for Martian entry problem, the reaction rates for oxidation and nitridation of carbon, rough surfaces, and the relationship ... |
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| Demonstration of Clean Particle Seeding for Particle Image Velocimetry in a Closed Circuit Supersonic Wind Tunnel |
MAR 2007 |
111 pages |
| Authors:
Charles M. McNiel; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The purpose of this research was to determine whether solid carbon dioxide (CO2) particles might provide a satisfactory, and cleaner, alternative to traditional seed material for Particle Image Velocimetry (PIV) for use in a closed circuit supersonic wind tunnel. The Air Force Institute of Technology (AFIT) closed circuit pressure-vacuum supersonic wind tunnel was utilized, which achieves a nominal Mach number of Mach 2.9 in a 2.5 inch by 2.5 inch ... |
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| Graphite and BN/AlN Annealing Caps for Ion Implanted SiC |
NOV 2006 |
8 pages |
| Authors:
M. C. Wood; K. A. Jones; T. S. Zheleva; K. W. Kirchner; M. A. Derenge; A. Bolonikov; T. S. Sudarshan; D. Vispute; S. S. Hullavarad; S. Dhar; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
|
| The activation of dopants for wide band-gap semiconductors such as SiC is a subject of much research. Silicon Carbide is problematic as Si sublimates from the SiC matrix at the temperatures required for activation. We have investigated the success of capping SiC substrates with more thermally stabile materials to impede Si sublimation. We present data taken from the SiC capping strategies using carbon and AlN/BN surface caps. We found that ... |
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| The Sublimation Rate of Dry Ice Packaged in Commonly Used Quantities by the Air Cargo Industry |
AUG 2006 |
8 pages |
| Authors:
Douglas C. Caldwell; Russell J. Lewis; Robert M. Shaffstall; Robert D. Johnson; FEDERAL AVIATION ADMINISTRATION OKLAHOMA CITY OK CIVIL AEROMEDICAL INST
|
| Dry ice is used as a refrigerant for the shipment of perishable goods in the aviation industry. The sublimation of dry ice can, however, lead to incapacitating levels of carbon dioxide in the aircraft cabin environment, as exemplified by the National Transportation Safety Board's (NTSB's) probable cause determination in a 1998 Brownsville, Texas, incapacitation incident. This incident prompted the NTSB to request that the Federal Aviation Administration (FAA) revisit the ... |
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| Computational Chemistry-Based Enthalpy-of-Formation, Enthalpy-of-Vaporization, and Enthalpy-of-Sublimation Predictions for Azide-Functionalized Compounds |
APR 2006 |
48 pages |
| Authors:
Michael J. McQuaid; Betsy M. Rice; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The applicability of semi-empirical models for estimating the gas-phase enthalpies-of-formation [deltafHog (298)], enthalpies-of-vaporization [ deltaHv (298)], and enthalpies-of-sublimation [deltaHs, (298)] of azide-functionalized compounds was evaluated. The models, which rely on B3LYP/6-31G(d) characterizations of the electronic properties of an isolated molecule of a compound, include (1) an atom-equivalent (AE) approach for estimating deltafHog (298) and (2) correlations for estimating deltaHv(298) and deltaH (298) from properties of the electrostatic potential on an ... |
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| First Structural Characterization of Binary As(III) and Sb(III) Azides |
2003 |
39 pages |
| Authors:
Ralf Haige; Ashwani Vij; Jerry Boatz; Stefan Schneider; Thorsten Schroer; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| The highly explosive molecules As (N3)3 and Sb(N3)3 were obtained for the first time in pure form by the reactions of the corresponding fluorides with (CH3)3SiN3 in SO2 solution and purification by sublimation. The crystal structures, 14N NMR and infrared and Raman spectra were determined and the results compared to ab initio second order perturbation theory calculations. Whereas Sb(N3)3 possesses a propeller-shaped, pyramidal structure with perfect C3 symmetry, the As(N3)3 ... |
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| Journal of Crystal Growth Volume 246, Nos. 1-2, pp.1-176, December 2002 |
01 DEC 2002 |
|
| Authors:
G. B. Stringfellow; M. Schieber; R. S. Feigelson; D. T. Hurle; R. Kern; ELSEVIER SCIENCE PUBLISHERS AMSTERDAM (NETHERLANDS)
|
 | Partial Contents: Classical semiconductors. Temperature control in InGaAs-based quantum well Structures grown by molecular beam epitaxy on GaAs (100) and GaAs (111)B substrates; Atomic depth distribution and growth modes of Sn on Si(1111 41-In and alpha-33-Au surfaces at room temperature; Enhanced impurity incorporation by alternate Te and S doping in GaAs prepared by intermittent injection of triethylgallium and arsine in ultra high vacuum; Defect-selective etching of GaN in a modified ... |
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| An Integrated Approach to III-Nitride Crystal Growth and Wafering |
OCT 2001 |
77 pages |
| Authors:
Z. Sitar; S. Beaudoin; D. Bliss; D. Brenner; M. Callahan; R. Davis; F. DiSalvo; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Centimeter size, transparent AlN crystals were grown at NCSU. TEM and XRT examination performed at ASU and SUNYSB revealed that the crystals are of highest quality and do not contain any visible extended defects. GaN crystals grown at Clemson by ammonothermal growth method have been grown to up to 5 mm in size. PL studies at ASU showed sharp excitonic emission, indicative of good quality. XRT showed mosaicity in some ... |
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| Predicting Heats of Formation of Energetic Materials Using Quantum Mechanical Calculations |
FEB 2001 |
24 pages |
| Authors:
Betsy M. Rice; Sharmila V. Pai; Jennifer Hare; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Quantum mechanical calculations are used to predict gas, liquid, and solid heats of formation of energetic molecules. A simple atom-equivalent method converts quantum mechanical energies of molecules and their atomic constituents to gas-phase heats of formation of energetic materials. Functional relationships between heats of vaporization and sublimation and properties associated with quantum, mechanically determined electrostatic potentials of isolated molecules are established. These are used with the gas-phase heats of formation ... |
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| Accelerated Program Development of High-Quality, Large-Area GaN and AlGaN Substrates |
12 AUG 1999 |
56 pages |
| Authors:
J. F. Schetzina; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| The purpose of this work was to explore growth of thick layers of GaN, AlN, and AlGaN for use as substrates in III-N device epitaxy using sublimation vapor phase epitaxy (SVPE). The SVPE system was a vertical, cold- wall, pancake-style reactor similar in design to a MOCVD reactor. Ammonia was used as a nitrogen source, while the group III precursors were gallium chloride, GaCl3, and aluminum ... |
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| Density Functional Calculations of Solid State Heats of Formation |
08 JUN 1999 |
17 pages |
| Authors:
Peter Politzer; M. E. Grice; Jane S. Murray; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| It is now feasible to compute quite accurate gas phase heats of formation for relatively small molecules by means of ab initio or density functional techniques and one of several possible approaches: formation reactions, atomization processes or isodesmic reactions. For larger molecules, some empirical correction terms are necessary, even when using density functional methods. Conversion of gas phase values to liquid and/or solid state heats of formation can be done ... |
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| European Conference on Silicon Carbide and Related Materials (2nd), Held in Montpeller, France on September 2-4, 1998 |
04 SEP 1998 |
318 pages |
| Authors:
MONTPELLIER UNIV (FRANCE)
|
| Partial Contents: (1) Progress in SiC: from material growth to commercial device development; (2) Advances in SiC materials and devices: an industrial point of view; (3) State of the art in the modelling of SiC sublimation growth; (4) Mathematical simulation of mass transfer, thermal transfer, and stress formation under silicon carbide boules growth; (5) Transport phenomena during sublimation growth of bulk SiC crystals; (6) Near- thermal equilibrium growth of SiC ... |
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| Mechanical/Thermal Jet Surface Interactions in Paint Stripping Processes |
14 AUG 1998 |
52 pages |
| Authors:
D. Parekh; A. Glezer; T. Crittenden; C Rogers; L. Meade; BOEING CO ST LOUIS MO PHANTOM WORKS
|
| Several key accomplishments of this program are highlighted below: Experimental results for the two-phase flow were obtained on a full-scale production paint stripping system since this was the best way to assure that the relevant flow and system parameters were being considered. (1) Several key characteristics of two-phase nozzle flow have been characterized, including CO2 pellet sizing, distribution, velocity, sublimation and breakup. Initial results from ... |
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| Computational Investigation of the Structures and Relative Stabilities of Amino/Nitro Derivatives of Ethylene |
27 APR 98 |
19 pages |
| Authors:
P. Politzer; M. C. Concha; M. E. Grice; J. S. Murray; P. Lane; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Eight amino and/or nitro derivatives of ethylene have been investigated computationally at the density functional B3P86/6-31+G** level. The molecular geometries and relative stabilities reflect the varying roles of "push-pull" electronic delocalization and intramolecular hydrogen bonding. The same two factors affect, to varying extents, the computed C-NO2 and C-NH2 bond dissociation energies, which are also presented, as are the heats of formation, vaporization and sublimation of the three diaminodinitroethylenes. The potential ... |
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| Computed Heats of Formation |
09 APR 98 |
5 pages |
| Authors:
Peter Politzer; M. E. Grice; Monica C. Concha; Pat Lane; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| We have computed heats of formation for compounds 1 - 8 (Table 1). The first five are target compounds proposed by M. Trudell (University of New Orleans); 6 - 8 have recently been prepared by R. Schmitt and J. Bottaro (SRI). For the molecular systems 1 - 7, we used our density functional procedure to obtain gas phase heats of formation, which were converted to liquid and solid state values ... |
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| Vapour Phase Growth of Thick Monocrystalline GaN Epitaxial Layers by Sandwich-Method |
OCT 97 |
60 pages |
| Authors:
E. N. Mokhov; Yu. A. Vodakov; A. D. Roenkov; P. G. Baranov; M. E. Boiko; JOINT STOCK CO AGENCY FOR SCIENCE AND TECHNOLOGY SAINT PETERSBURG (RUSSIA)
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| The basic investigations leading to the fabrication of thick (more than 0.2 mm) monocrystalline layers of GaN on the silicon carbide substrates are performed. GaN layers were grown by sublimation sandwich-method in ammonia atmosphere. GaN polycrystalline powder and metallic Ga were used as a vapor source. The growth was carried out in quartz reactors both horizontal, and vertical types, in furnaces with high-frequency heating. The possibility of growing of thick ... |
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| Vapour Phase Growth of Thick Monocrystalline GaN Epitaxial Layers by Sandwich-Method |
FEB 97 |
17 pages |
| Authors:
E. N. Mokhov; Yu. A. Vodacov; A. D. Roenkov; P. G. Baranov; M. E. Boiko; EUROPEAN RESEARCH OFFICE LONDON (UNITED KINGDOM)
|
| Comparison studies of the crystal quality of SiC substrates grown by Lely method and sublimation sandwich method (SSM) was conducted. SSM-substrates was shown to have considerably promise for high quality GaN epilayers growth. Conditions of the surface treatment of the SiC substrates were optimized for GaN epilayers growth. The best results were reached on very close to (0001) Si- substrate surfaces etched by sublimation technique. Monocrystalline GaN layers was shown ... |
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| Vapour Phase Growth of Thick Monocrystalline GaN Epitaxial Layers by Sandwich-Method |
01 DEC 96 |
14 pages |
| Authors:
E. N. Mokov; Yu. A. Voda kov; A. D. Roenkov; P. G. Baranov; M. E. Boiko; JOINT STOCK CO AGENCY FOR SCIENCE AND TECHNOLOGY SAINT PETERSBURG (RUSSIA)
|
| We have modified a setup for growing GaN heteroepitaxial layers of large area and obtained 20 such structures on silicon carbide (SiC) and sapphire (Al2O3) substrates of 8 mm2 in size 50-150 micrometers thickness by Sublimation Sandwich Method (SSM). The substrates have been analysed for optimal GaN layer growth conditions, using the available data, and the results indicated that hexagonal SiC (alpha-SiC) is the best material. The substrate/epilayer mismatches may ... |
|
| 1ST European Conference on Silicon Carbide and Related Materials |
OCT 96 |
|
| Authors:
ARISTOTLE UNIV OF THESSALONIKI (GREECE)
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|
| Glaciers, Ice Sheets and Volcanoes: A Tribute to Mark F. Meier |
OCT 96 |
134 pages |
| Authors:
Samuel C. Colbeck; COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
|
| This volume is dedicated to the professional contributions of Mark Meier. It contains a mixture of papers on snow, glaciers, ice sheets, and volcanoes, and therefore reflects his interests and research contributions. The papers were presented at the 1995 Fall meeting of the American Geophysical Union. |
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| Controlling Mechanisms of Pulsating Incineration Processes |
30 SEP 96 |
90 pages |
| Authors:
B. T. Zinn; J. I. Jagoda; L. M. Matta; GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
|
| The purpose of this research program is to study the fundamental processes that control the performance of acoustically excited incineration systems. The information learned will be used in the development of a compact, high efficiency waste incinerator for shipboard use. Tests performed during the course of this program have demonstrated that mixing and heat transport processes, both crucial to the incineration process, can be enhanced by imposing acoustic oscillations. Because ... |
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| Dredging in an Active Artillery Impact Area. Eagle River Flats, Alaska |
SEP 96 |
52 pages |
| Authors:
Michael R. Walsh; Edwin J. Chamberlain; Karen S. Henry; Donald E. Garfield; Ed Sorenson; COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
|
| Ongoing investigations into the waterfowl die-offs and the persistence of the causal agent, white phosphorus, in Eagle River Flats, an estuarine salt marsh and military impact area, indicate that any remediation strategy will have to include consideration of removal and controlled processing of contaminated sediments. Contaminated areas that are constantly flooded, such as the deeper ponded areas, do not allow natural drying of the soil and subsequent sublimation of the ... |
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| Nanostructured Bearing Alloy Studies |
10 AUG 96 |
5 pages |
| Authors:
K. E. Gonsalves; CONNECTICUT UNIV STORRS INST OF MATERIALS SCIENCE
|
| This period marks the transition in the powder making from the Co- Reduction method to the Thermal Decomposition. The latter method was studied earlier in this program and was dropped in favor the Co-Reduction method because of the better chemical homogeneity in powder produced by the Co-Reduction method. The main drawbacks for the Co-Reduction methods for making M50 powder are the high cost of the chemical precursors and the lengthy ... |
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| Chemical Mechanisms at the Burning Surface |
15 MAR 96 |
127 pages |
| Authors:
Thomas B. Brill; DELAWARE UNIV NEWARK DEPT OF CHEMISTRY
|
| Chemical mechanisms and kinetics are described for the surface reaction zone of materials of interest in solid rocket propellants. The technique used is flash thermolysis of films by T-jump-Fourier transform infrared spectroscopy. The potential for burn rate modification by a wide variety of related nitrogen heterocyclics was uncovered. The kinetics of decomposition of HMX, RDX and NTO were evaluated and critically analyzed. It was found that a kinetic compensation effect ... |
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| Computational Determination of Heats of Formation of Energetic Compounds. |
25 JAN 1996 |
14 pages |
| Authors:
Peter Politzer; Jane S. Murray; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| A recently-developed density functional procedure for computing gas phase heats of formation is briefly described and results for several categories of energetic compounds are summarized and discussed. Liquid and solid phase values can be obtained by combining the gas phase data with heats of vaporization and sublimation estimated by means of other relationships. Some observed functional group effects upon heats of formation are noted. jg p1 |
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| Predicted Heats of Formation of DNAF in Gaseous, Liquid and Solid Phases. |
10 OCT 1995 |
3 pages |
| Authors:
Peter Politzer; Jane S. Murray; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| One of the compounds for which we have recently computed the gas phase heats of formation, delta H sub f gaseous), is DNAF, 1 (1). This was done using our density functional procedure (2). In response to interest expressed by the Air Force Armament Laboratory (Eglin AFB), we have now estimated the liquid and solid phase heats of formation of 1. For this purpose, we needed the heats of vaporization, ... |
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| Controlling Mechanisms of Pulsating Incineration Processes |
30 SEP 95 |
45 pages |
| Authors:
B. T. Zinn; J. I. Jagoda; L. M. Matta; GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
|
| The purpose of this research program is to study the fundamental processes that control the performance of acoustically excited incineration systems. The information learned will be used in the development of a compact, high-efficiency waste incinerator for shipboard use. Tests performed during the current reporting period of this program have demonstrated that mixing and heat transport processes, both crucial to the incineration process, may be enhanced by imposing acoustic pressure ... |
|
| Self-Assembly of Low-Dimensional Molecular Nanoclusters on Au(111) Surfaces |
08 DEC 94 |
34 pages |
| Authors:
Joachim H. Schott; Christopher M. Yip; Michael D. Ward; MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE
|
| Two-dimensional nanoclusters of (TTF)(TCNQ) (TTF = tetrathiafulvalene, TCNQ - tetracyanoquinodimethane) and Li+TCNQ-, formed on Au( 111) surfaces by vapor phase sublimation under ambient conditions prior to growth of bulk crystals of these low-dimensional organic conductors, have been observed with scanning tunneling microscopy (STM) and scanning electron microscopy (SEM). The molecular planes of the constituents in individual nanoclusters are oriented perpendicular to the Au(111) substrate, while the clusters exhibit azimuthal orientations ... |
|
| Low Temperature Deposition and Characterization of N- and P-Type Silicon Carbide Thin Films and Associated Ohmic and Schottky Contacts |
DEC 94 |
39 pages |
| Authors:
Robert F. Davis; Robert J. Nemanich; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| Exposure of heated 6H-SiC wafers to SiH4 contained both in a gas stream and an activated plasma was investigated for low temperature SiC cleaning and oxygen removal prior to thin film deposition. UPS revealed the first observation of surface states on the cleaned 6H-SiC surface. Monocrystalline epitaxial films of Beta(3C)-SiC(111) and alpha(6H)-SiC(0001) were grown on vicinal (approx. 3.50 deg off(0001) towards) alpha(6H)-SiC(0001) substrates via gas-source MBE from 1050 to 1250 ... |
|
| Photoluminescence Spectroscopy of 4H- and 6H-SiC |
DEC 94 |
81 pages |
| Authors:
William A. Davis; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| Typical undoped bulk grown SiC shows n- or p-type conductivity due to residual impurities such as nitrogen, boron, or aluminum. In order to produce high resistivity material, vanadium can be used as a compensating dopant. Since vanadium is an amphoteric dopant in SiC, it produces either a donor state, V sub Si (4+) (3d sup 1 )-> V sub Si(5+) (3d sup 0), or an acceptor state, V sub Si(4+) ... |
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| Controlling Mechanisms of Pulsating Incineration Processes |
29 SEP 94 |
33 pages |
| Authors:
B. T. Zinn; J. I. Jagoda; L. M. Matta; C. Zhu; GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
|
| The goal of this study is to investigate the fundamental processes that control the performance of acoustically excited incineration systems. Cold flow tests performed under the first year of this program have demonstrated that natural acoustic mode oscillations, in the absence of net flow into or out of the volume, can be used to promote rapid mixing. Increased acoustic pressure amplitudes in the chamber were shown to increase the mixing ... |
|
| Near-Resonant Properties of Nonlinear Organic Materials for Optical Devices |
14 SEP 94 |
6 pages |
| Authors:
George Stegeman; UNIVERSITY OF CENTRAL FLORIDA ORLANDO
|
| The nonlinear optics of sublimated films of 2-dimensional conjugated planar molecules has been investigated by third harmonic generation. Two were planar phthalocyanines, metal-free and copper substituted, and the third was an asymmetric (non-planar) phthalocyanine (subphthalocyanine), employed as a precursor in the synthesis of certain phtalocyanines. A very rich spectrum has been observed in each case and the analysis is currently underway. In the future this work will be expanded to ... |
|
| Experimental Investigation of Optical Nonlinearities in Conjugated Polymers |
31 AUG 94 |
6 pages |
| Authors:
George Stegeman; UNIVERSITY OF CENTRAL FLORIDA ORLANDO CENTER FOR RESEARCH IN ELECTRO-OPTICS A ND LASERS
|
| The nonlinear optics of sublimated films of 2-dimensional conjugated planar molecules has been investigated by third harmonic generation. Two were planar phthalocyanines, metal-free and copper substituted, and the third was an asymmetric (non-planar) phthalocyanine (subphthalocyanine), employed as a precursors in the synthesis of certain phtalocyanines. A very rich spectrum has been observed in each case and the analysis is currently underway. In the future this work will be expanded to ... |
|
| The Properties of Di-(2-Chloroethyl) Sulfide, 2. Thermodynamic Calculations, Data Review, and Analysis |
JUL 94 |
|
| Authors:
Elwin C. Penski; EDGEWOOD RESEARCH DEVELOPMENT AND ENGINEERING CENTER ABERDEEN PROVING GROUND MD
|
| This investigation is one phase of an effort to build a data foundation for thermodynamic properties of agents. This report is the second in a series of reports on the properties of di-(2-chloroethyl) sulfide. Some property values are calculated from the best methods available, and in other cases, the best values are selected from the literature. Values are selected at standard conditions for 17 different properties. Information on calculating the ... |
|
| Snapshots of Crystal Growth: Nanoclusters of Organic Conductors on Au(111) Surfaces |
23 JUN 94 |
18 pages |
| Authors:
J. H. Schott; M. D. Ward; MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE
|
| Mono- and multilayer crystalline nanoclusters of tetra-hiafulvalene- tetracyanoquinodimethane ((TTF) (TCNO)), a low-dimensional organic conductor in the bulk form, can be formed readily on Au(111) surfaces by vapor phase sublimation under ambient conditions. Scanning tunneling microscopy of monolayer (TTF)(TCNQ) films reveals a two-dimensional density of states (DOS) that is consistent with the arrangement of TTF and TCNO molecules in the ac face of bulk (TTF)(TCNO), in which the molecular planes are ... |
|
| Self-Assembly of Low-Dimensional Conductors on Au(111) Surfaces |
23 JUN 94 |
32 pages |
| Authors:
J. H. Schott; M. D. Ward; MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE
|
| Two-dimensional nanoclusters of (TTF) (TCNQ) (TTF = tetrathiafulvalene TCNQ = tetracyanoquinodmethane) and Li+ TCNQ-, formed on Au (111) surfaces by vapor phase sublimation under ambient conditions prior to growth of bulk crystals of these low-dimensional organic conductors, have been observed with scanning tunneling microscopy (STM) and scanning electron microscopy (SEM). The molecular planes of the constituents in individual nanoclusters are oriented perpendicular to the Au (111) substrate, while the clusters ... |
|
| Quarterly Report for Contract N00014-92-J-1308 (Lehigh University) |
94 |
|
| Authors:
Ralph J. Jaccodine; LEHIGH UNIV BETHLEHEM PA SHERMAN FAIRCHILD CENTER FOR SOLID STATE STUDIES
|
| Research has begun on SiGe oxidation in situ in a UHV chamber with high resolution XPS. In this phase of the work, the early stages of oxidation are being studied as a chemisorbed layer of oxygen on clean silicon (100) is converted to a thin (900 deg C with excellent uniformity over a 1 sq. cm area. An optical pyrometer suitable for transmission through a quartz vacuum window was recently ... |
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| Interface Properties of Wide Bandgap Semiconductor Structures |
DEC 93 |
212 pages |
| Authors:
Robert F. Davis; Salah Bedair; Jerry Bernholc; Jeffrey T. Glass; R. J. Nemanich; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| Ab initio molecular dynamics calculations have shown that the lxl:2H and the 2xl:H surfaces of diamond(C)(100) have a (-) electron affinity(EA); the clean (100) surface has a (+) EA. This is in agreement with experiment. Biased nucleation of C on Beta-SiC(100) and Si(100) has been achieved but not on Cu(100). C nucleation densities on Hf, Ti, Ta, Ni and W were directly related to the carbide heat of formation. The ... |
|
| Chemical Properties of the Fullerenes |
NOV 93 |
46 pages |
| Authors:
Allan L. Smith; BATTELLE MEMORIAL INST COLUMBUS OH
|
| The UV-visible absorption spectra of pure C60, C70, and C60O dissolved in toluene were used to perform multicomponent analysis of graphitic soot extracts and to assess the purity of fullerene samples. Diffuse-reflectance FTIR spectroscopy of 1-2 mg solid C60 and C70 samples was used to determine the fraction of hydrocarbon impurities at the level of 0.01 atom fraction H. Vacuum sublimation is the only way to produce C60 and C70 ... |
|
| Volatile CVD Precursors Based on Copper Alkoxides and Mixed Group IIA-Copper Alkoxides. |
25 MAY 1993 |
|
| Authors:
Andrew Purdy; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| Fluorinated alkoxy compounds of copper, copper-calcium, copper-strontium, and copper-barium having a certain structure in which 1 less than or equal w less than or equal 4; R is a fluorinated alkyl group; x greater than or equal 1; Y is an alkoxy or alkyl group without beta-hydrogen; Y greater than or equal 0; w less than or equal (x+y) less than or equal 2w; L is a Lewis base; 1 ... |
|
| Growth of Single Crystal Beta Silicon Carbide |
DEC 92 |
34 pages |
| Authors:
Kee-Chang Yoo; Warren Ruderman; INRAD INC NORTHVALE NJ
|
| Beta-SiC is a promising, wide bandgap material for high power electronic devices capable of operation at high temperatures. Its high saturation velocity, high breakdown electric field, and high thermal conductivity point to superior performance for high frequency applications. The successful fabrication of Beta-SiC devices requires high quality films to be epitaxially grown on lattice-matched substrate materials. Single crystals of Beta-SiC offer the optimum substrate material for lattice matching. The major ... |
|
| Hybrid Oxygen System |
OCT 1992 |
199 pages |
| Authors:
W. D. Lee; LITTLE (ARTHUR D) INC CAMBRIDGE MA
|
| Investigation of concepts for generating oxygen on-board combat aircraft and development of a bleed air-driven refrigeration, liquefaction, and cryogenic storage system for oxygen were undertaken in this study. A number of alternative approaches were examined while considering size, weight and power consumption. An open-loop bleed air-driven system was selected for design, development, and testing. The bleed air-driven refrigeration unit achieved oxygen liquefaction temperatures of 90 deg K and liquefied and ... |
|
| Microwave Thermogravimetric Analyzer (MTGA), |
27 APR 1992 |
|
| Authors:
Edmund H. Moore; Iftikhar Ahmad; David E. Clark; FLORIDA UNIV GAINESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| A Microwave Thermogravimetric Analyzer (MTGA) has been constructed, which allows for the measurement of weight change of a sample located within a 2.45 GHz microwave cavity, as a function of temperature. Samples in the powdered or compact form, are heated by microwave hybrid heating (MHH). These samples are placed inside an inert holder and subjected to a known reproducible thermal profile, which allows the material to be characterized. Changes in ... |
|
| Mechanical Properties of Semiconductors and Their Alloys |
FEB 92 |
330 pages |
| Authors:
A. Sher; M. A. Berding; A. T. Paxton; . Krishnamurthy; A.-b. Chen; SRI INTERNATIONAL MENLO PARK CA
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| A wide range of subjects have been treated in this contract. We have devoted time to the development and applications of two first principles computational methods: one, the full-potential linear muffin tin orbital (FP- LMTO) method is somewhat mature and highly accurate, while the other, linear combination of atomic orbitals (LCAO), is less accurate but more flexible and is easily incorporated into the other calculations we have in place, e.g., ... |
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| Freeze-Dried Human Red Blood Cells |
15 JAN 92 |
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| Authors:
CRYOPHARM PASADENA CA
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| The research activities described in this report summarize our progress on lyophilized human red blood cells (RBC) since the last Progress Report. Our primary research efforts for this funding period have thus focused on the following areas: (1) development of improved new buffer formulations based on the glass transition and water replacement theories; (2) establishing freezing conditions such that normal cell indices are maintained prior to drying and allow for ... |
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| Volatile Barium Beta-Diketonate Polyether Adducts. Synthesis, Characterization and Metalorganic Chemical Vapor Deposition |
31 MAY 91 |
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| Authors:
Robin A. Gardiner; Duncan W. Brown; Peter S. Kirlin; Arnold L. Rheingold; ADVANCED TECHNOLOGY MATERIALS INC DANBURY CT
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| The 2,5,8,11,14-pentaoxaheptadecane (tetraglyme) adducts of barium complexes of 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (H(hfacac(), 1,1,1,- trifluoro-2,4-pentanedione (Htfacac) and 2,2,6,6-tetramethyl-3,5-heptanedione (H(thd)) have been prepared and characterized by X-ray crystallography, H and C nmr spectroscopies, melting and sublimation points, and elemental analysis. The thermal stability of the complexes is related to their solid state structure in which the coordination number around the barium atom is nine with a monocapped, twisted square prism structure. Metalorganic chemical vapor ... |
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| Activated-Surface Chemical Vapor Deposition |
25 FEB 91 |
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| Authors:
Alan Gallagher; STATE UNIV OF NEW YORK AT BINGHAMTON CENTER FOR LEADERSHIP STUDIES
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| The purpose of this study has been to construct and to achieve operation of a high-resolution, ultra high vacuum scanning tunneling microscope (STM) and to use the instrument to reveal the chemistry and physics of surface modification, etching or deposition that can be induced by the STM current. Typical approaches to the operational requirements of the STM are described: (1) The mechanical structure of the STM must allow a large ... |
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| Development and Verification of a Physical Cloud-Moisture Model for Use in General Circulation Models |
31 JAN 91 |
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| Authors:
J. L. Lee; K. N. Liou; S. C. Ou; UTAH UNIV SALT LAKE CITY CENTER FOR ATMOSPHERIC AND REMOTE SOUNDING STUDIES
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| A time dependent, three dimensional, large-scale cloud moisture model has been developed for the prediction of cloud cover, cloud liquid/ice water content (LWC/IWC), precipitation, specific humidity and temperature. Partial cloudiness is allowed to form when large-scale relative humidity is less than 100%. In the vertical, a 16-layer z-coordinate is adopted. The horizontal resolution is described by 48 equally-spaced longitudinal points and 38 Gaussian latitudes. The wind field is prescribed using ... |
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| Mechanical Properties of Semiconductors and their Alloys |
NOV 90 |
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| Authors:
A. Sher; M. A. Berding; M. van Schilfgaarde; S. Krishnamurthy; A. T. Paxton; SRI INTERNATIONAL MENLO PARK CA
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| This annual report of AFOSR contract F49620-88-K-0009 summarizes the work accomplished on studies of mechanical properties of semiconductors and their alloys, and plastic flow and intermetallic compounds. (1) A simple relationship between the elastic constants of semiconductor is found. (2) A systematic study of tight-binding parameters to fit cohesive energy, bulk modulus, and shear coefficients of all diamond and zinc-blende semiconductors has been carried out. (3) An additional, nonequilibrium mechanism ... |
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