Scientific and Technical Aerospace Reports Volume 39 April 6, 2001

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x 0.4 micro disk/donuts made of PMMA. Using this technology virtually any two dimensional shape, disk, rod, banana, etc. can be made readily. Three dimensionally shaped colloidal particles can be prepared but with more difficulty. Author (revised) Microscopy; Colloids; Nucleation; Crystal Growth; Crystallization 20010024899 Harvard Univ., Cambridge, MA USA Physics of Colloids in Space Weitz, Dave, Harvard Univ., USA; Weeks, Eric, Harvard Univ., USA; Gasser, Urs, Harvard Univ., USA; Dinsmore, Tony, Harvard Univ., USA; Mawley, Suliana, Harvard Univ., USA; Segre, Phil, NASA Marshall Space Flight Center, USA; Cipelletti, Lucia, Montpellier Univ., France; Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp. 252-277; In English; See also 20010024890; No Copyright; Avail: CASI; A03, Hardcopy; A10, Microfiche This talk will present recent results from ground-based research to support the ”Physics of Colloids in Space” project which is scheduled to fly in the ISS approximately one year from now. In addition, results supporting future planned flights will be discussed. Author (revised) Colloids; Microgravity; Microscopy; Crystallization 20010024900 Pennsylvania Univ., Philadelphia, PA USA Colloidal Assembly in Entropically Driven, Low-Volume-Fraction Binary Particle Suspensions Yodh, A. G., Pennsylvania Univ., USA; Sanyal, S., Pennsylvania Univ., USA; Zhang, J., Pennsylvania Univ., USA; Work, W. J., Pennsylvania Univ., USA; Lin, K. -H., Pennsylvania Univ., USA; Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp. 278-313; In English; See also 20010024890; No Copyright; Avail: CASI; A03, Hardcopy; A10, Microfiche We describe entropic depletion-induced assembly experiments to synthesize novel colloidal crystals. Our samples are typically a mixture of large and small species suspended in water or in an organic liquid. The larger particles are spherical colloids with diameter ranging from 0.4 to 3 microns, and its type range from polymer-based spheres such as polymethylmethacrylate (PMMA), polystyrene (PS) and silica, to semiconductors such as ZnS, to novel polymer-based spheres that have hollow interiors. The small species can be a polymer (e.g. PS polymer), a micelle (e.g. SDS micelles), a dendrimer, or a very small colloidal particle. Typically an optical grating template is bonded to one wall of our microscope slide cells to select particular colloidal crystal types. We have investigated the entropic self-assembly of colloidal spheres on periodic patterned templates. A variety of two-dimensional structures with quasi-long-range order are observed to form on templates with one- and two-dimensional periodic structure. In particular, on a template commensurate with an FCC (100) plane, entropic forces induced by non-adsorbing polymers form an FCC crystal more than 30 layers thick without random stacking defects. We have also begun particle synthesis experiments to achieve samples of monodisperse colloidal suspensions of the types mentioned above. So far our successes in this endeavor are as follows: (1) We could modify a published technique to synthesize 140 nm and 400 nm ZnS particles with size-dispersity is less than 5%. In principle this same procedure can be applied to synthesize a range of similar sulfides, e.g. CdS, SnS, PbS, MnS; (2) We have prepared monodisperse particles that have a water-swollen core (precursor to hollow sphere particles) with particle sizes in the 550-650 nm range. Initial success of their assembly by depletion techniques has been achieved in our laboratory; and (3) We have also succeeded in synthesizing 100 nm, 200 nm, and 600 nm monodisperse (is less than 10%) magnetic particles following a literature technique. We will describe experiments to measure the photonic band-structure of some of these crystals using a spectrophotometer set up in our laboratory, which can perform angle- and wavelength-resolved reflection and transmission experiments on our colloidal crystalline samples. Author (revised) Colloids; Polymethyl Methacrylate; Self Assembly; Crystal Growth; Entropy 20010024901 Stanford Univ., Dept. of Chemical Engineering, Stanford, CA USA Micromechanics and Dynamics in Magnetorheological Suspensions Gast, A., Stanford Univ., USA; Furst, Eric, Stanford Univ., USA; Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp. 314-335; In English; See also 20010024890; No Copyright; Avail: CASI; A03, Hardcopy; A10, Microfiche Magnetorheological (MR) suspensions are composed of paramagnetic colloidal particles that acquire dipole moments when subjected to an external magnetic field. At sufficient field strengths and concentrations, the dipolar particles rapidly aggregate to form long chains. Subsequent lateral cross-linking of the dipolar chains is responsible for a rapid liquid-to-solid-like rheological transition. The unique, magnetically-activated rheological properties of MR suspensions make them ideal for electrical-mechani- 70
cal transducers. Additionally, the ability to experimentally probe colloidal suspensions interacting through tunable anisotropic potentials is of fundamental interest. In this talk we will describe our work toward a microscopic understanding of magnetorheological behavior. Much of the rheological behavior arises from the cross-linked structure caused by defects and Landau-Peierls thermal fluctuations of dipolar chains. We used the light scattering technique, diffusing-wave spectroscopy, to investigate the fluctuations of dipolar chains. We have prepared monodisperse neutrally buoyant MR suspensions allowing us to probe the dynamics of the dipolar chains using light scattering without complications due to gravitational forces and polydispersity. Optical gradient force trapping techniques, or laser tweezers, have become increasingly important tools for studying the microscopic structure, mechanics, and interactions in biological, colloidal, and macromolecular materials. We also present our study of the micromechanical properties of dipolar chains and chain aggregates in a magnetorheological suspension. Using dual-trap optical tweezers, we are able to directly measure the deformation of dipolar chains parallel and perpendicular to the applied magnetic field. We observe the field-dependence of chain mechanical properties, such as tensile strain, chain reorganization, defect-annealing and rupture. We discuss the role these forms of energy dissipation take in the yield stress and rheology of MR suspensions. Author (revised) Magnetorheological Fluids; Suspensions; Crosslinking; Colloids 20010024902 Colorado Univ., Dept. of Physics, Boulder, CO USA Freely Suspended Smectic Filaments and the Structure of the B7 Phase of MHOBOW Clark, N., Colorado Univ., USA; Link, D. R., Colorado Univ., USA; Maclennan, J. E., Colorado Univ., USA; Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp. 337-339; In English; See also 20010024890; No Copyright; Abstract Only; Available from CASI only as part of the entire parent document Our recent discovery of the spontaneous formation of chiral domains in fluid smectic phases of achiral bow-shaped molecules opens up a wide variety of possibilities for new liquid crystal phases and phenomena. The basic, spontaneously chiral layer structure of the highest temperature fluid smectic phases, the B2 and B7, are shown. One of the most intriguing aspects of this structure is the plethora of possible phases coming from different stacking sequences of the polar ordering and tilt directions. The four possibilities of next-nearest neighbor alternation are shown. In the original material studied, NOBOW, the ground states found are antiferroelectric, either the racemic SmC(sub S)P(sub A) or the chiral SmC(sub A)P(sub A). We are currently studying MHOBOW, synthesized by D. Walba which, by virtue of its methyl hexyloxy tail has a tendency to form anticlinic layer interfaces, in the hope of finding a phase with a ferroelectric ground state, either SmC(sub A)P(sub S) or SmC(sub S)P(sub A), which can be obtained in NOBOW only by applying a field. Preliminary observations of MHO-BOW have made its study, from the point of view of understanding novel LC structures, extremely high priority. The following truly remarkable characteristics have been revealed: (i) The smectic phase grows out of the isotropic in the form of helical ribbons. The resulting planar aligned textures of focal conics with layers normal to glass plates exhibit bizarre modulations, including stripes and checker-boards. These have also been seen in other materials suggesting that this is a new phase (tentatively called B7), which is a fluid smectic with some kind of in-layer structure. (ii) It is virtually impossible to make freely suspended films of MHOBOW. Rather it makes the freely suspended filaments which preliminary x-ray scattering experiments reveal to have the nested cylinder layer structure indicated; (iii) The powder x-ray diffraction exhibits four resolution-limited smectic layering peaks, very close in layer spacing, which vary continuously with T. This is further evidence for a more complex three dimensional structure than NOBOW, which has a typical single layering reflection. (iv) The x-ray structure factor of the layering peak of the filaments is extraordinarily complex and rich. Varying in qL (the scattering vector component along the filament axis) from a double slit-like pattern to modulated layer-like patterns, as qH (the scattering vector component normal to the filament axis) is varied over the range where the four powder peaks are located. These results suggest some kind of mosaic structure, perhaps with different layer spacings corresponding to the different stacking sequences. Recent x-ray diffraction experiments show that the peaks are modulated in intensity upon translation along a filament, in domains of several hundred microns dimension. These preliminary experiments suggest that the B7 is a fluid smectic with extremely unusual and fascinating structures. of all of the many hundreds of fluid smectic materials we have attempted to study in the freely suspended film geometry over the years, only a few have failed to form films, and none showed any great tendency to form filaments, although this clearly should be a possible freely suspended smectic LC morphology. On several ocCASIons in the past we have intentionally tried to make filaments from a variety of smectics without success. Thus the smectic filament formation property makes the B7 phase unique. It seems quite likely that the stability of filaments is related to the in-plane structure. The filaments exhibit other interesting structural and optical features. They are birefringent with a local optic axis which is oblique and which can vary continuously along filament and which can be manipulated with an electric field applied normal to the fiber, as if the field were causing a rotation of the optic axis about the fiber axis. Rapid displacement of the ends of the fiber 71
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Scientific and Technical Aerospace
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Introduction Scientific and Technic
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Subject Divisions Table of Contents
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Subject Categories of the Division
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73 Nuclear Physics 263 Includes nuc
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Document Availability Information T
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Avail: NASA Public Document Rooms.
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Hardcopy & Microfiche Prices Code N
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ALABAMA AUBURN UNIV. AT MONTGOMERY
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03 AIR TRANSPORTATION AND SAFETY
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work of the JAA had established thi
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20010024868 Federal Aviation Admini
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20010023437 Defence Science and Tec
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The Models for Aeroelastic Validati
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20010025824 Pratt and Whitney Aircr
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20010023064 NASA Langley Research C
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17 SPACE COMMUNICATIONS, SPACECRAFT
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Page 43 and 44: The objective of the proposed resea
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Page 47 and 48: ustion, showing that these can have
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Page 51 and 52: film. Subsequent electroless metal
Page 53 and 54: 20010024029 Houston Univ., Dept. of
Page 55 and 56: equipment indicate a change in the
Page 57 and 58: interaction, the main gas products
Page 59 and 60: Contract(s)/Grant(s): W-7405-eng-48
Page 61 and 62: for detecting and measuring deviato
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Page 65 and 66: 20010026182 Oak Ridge National Lab.
Page 67 and 68: 20010024162 Army Research Lab., Ade
Page 69 and 70: matching funds. MIRSL purchased an
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Page 73 and 74: 20010026217 Princeton Univ., NJ USA
Page 75 and 76: 20010024108 Center for Naval Analys
Page 79 and 80: undertaken to isolated it are descr
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Page 87 and 88: 20010024042 Houston Univ., Dept. of
Page 89 and 90: The research carried out in the Hea
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Page 97 and 98: This project represents a combined
Page 99 and 100: 20010024910 Johns Hopkins Univ., De
Page 101 and 102: e caused by a non-uniform temperatu
Page 103 and 104: metric shear cell, employed upon th
Page 105 and 106: 20010024919 Alabama Univ., Huntsvil
Page 107 and 108: Newtonian fluids in the laboratory,
Page 109 and 110: Boussinesq convection where due to
Page 111 and 112: 20010024930 Creare, Inc., Hanover,
Page 113 and 114: Illumination of a space-borne objec
Page 115 and 116: The hydrodynamics near steadily mov
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Page 119 and 120: liquid crystal host. Since the ulti
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Page 139 and 140: particle size was studied. In a den
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20010024983 Notre Dame Univ., Physi
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20010024986 TDA Research, Inc., Whe
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drop deposition, using Schiaffino a
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and extended to reduced gravity flo
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from an isolated bubble regime to a
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20010025000 Case Western Reserve Un
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our experimental measurements and w
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sured using a hot film probe flush
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the stationary bubble entrains anot
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we have collaborated on 3D experime
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of the most attractive characterist
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apply either steady shear flow perp
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20010025024 NASA, Washington, DC US
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neously the gamma scattered method
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20010023125 Colorado Univ., Lab. fo
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Contract(s)/Grant(s): F19628-95-C-0
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ics Technology Letters; March 2000;
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The BOREAS RSS-1 team collected sur
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ically corrected; however, files of
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with wavelength bands specific to t
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20010022099 NASA Goddard Space Flig
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within the polygon). There are thre
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A03, Hardcopy; A01, Microfiche Cana
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storms in Africa and smoke plumes f
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Greenland, with the objective of qu
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The BOReal Ecosystem-Atmosphere Stu
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The BOREAS TGB-8 team collected dat
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Report No.(s): NASA/TM-2000-209891/
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The BOREAS TF-10 team collected tow
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cally Active Radiation (FPAR) absor
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tributing to the overall understand
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cal ’tour de force’ allows EPV
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20010023558 Texas Univ., Center for
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the atmospheric concentrations of m
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20010023278 Lembaga Penerbangan dan
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Atmospheric radiation in the infrar
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20010022976 Desert Research Inst.,
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The primary purpose of AASERT Grant
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with only small ice-covered areas r
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Task 2 - abstraction of Medical rec
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non-steroidal activators of the rec
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20010023796 Massachusetts Univ. Med
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20010024166 Chicago Univ., Chicago,
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20010025069 Cleveland Clinic Founda
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Prior to 1994, measurement of tumor
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20010025730 Illinois Univ., Broad o
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the processing for enhancement of s
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strides in detection, diagnosis, an
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20010025763 California Univ., Lawre
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The ability to detect carcinoma cel
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ations found in clinical and geneti
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20010021850 Michigan Univ., Dept. o
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20010021985 National Inst. of Healt
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20010023264 Department of Health an
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on the BBB in rats, researchers not
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navigation method shows an advantag
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ange, and for some combinations of
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consider two specific issues in app
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planning with the Remote Agent expe
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training courses for the CAD tools.
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In this report, we consider the pro
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of the neural network and hence, th
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65 STATISTICS AND PROBABILITY �
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from the Lagrangian of the system.
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The average U-235 neutron total cro
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20010026201 Sandia National Labs.,
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to be 8.5-10.5 degrees which concur
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77 PHYSICS OF ELEMENTARY PARTICLES
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20010026247 Abdus Salam Internation
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Board (Access Board) under the auth
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currently underway or planned durin
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transfer function that would cover
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90 ASTROPHYSICS ��
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strates that as the gyroradius incr
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20010023043 Jet Propulsion Lab., Ca
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climatic variations. This can only
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try), allowing the same samples, in
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This work will describe the Thermal
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20010023068 Tennessee Univ., Dept.
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is crucial to the successful landin
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flat-plate Michelson interferometer
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general public is definitely intere
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exploration, examine specific optio
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tions of water. Often, due to lower
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With the exploration strategy for M
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necessary to ensure delivery of a s
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spectral studies to the field, and
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93 SPACE RADIATION ��
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ATMOSPHERIC RADIATION, 163, 205 ATM
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DEW POINT, 165 DIAGNOSIS, 217, 220,
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GRAVITATION, 54, 84, 88, 110, 111,
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MATRIX THEORY, 270 MEASURING INSTRU
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ST-10 Q QUALITY CONTROL, 11, 213 QU
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ST-12 T TARGET RECOGNITION, 265 TAS
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A Abdelguerfi, Mahdi, 252 Abramo, R
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Cledassou, R., 311 Clemmet, J., 306
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Gorelick, N., 294 Gorevan, S. P., 4
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Kupinski, Matthew A., 256 Kuznetz,
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Parks, C. H., 249 Parr, T. P., 38 P
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Swisdak, Michael M., Jr., 37 Szalew
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Scientific and Technical Aerospace Reports Volume 39 April 6, 2001

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