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Substrate Influenced Nucleation and Crystallization of LinbO 3 Thin Films Made by Sol-Gel

MRS Online Proceedings Library 1993年第1期310卷 287-292页

作者： Vikram Joshi Debasis Roy Martha L. Mecartney Department of Chemical Engineering and Materials Science University of Minnesota Minneapolis USA Materials Science and Engineering Program University of California Irvine USA

Lithium niobate films were deposited on amorphous carbon, silicate glass, (0001) sapphire, and (100) silicon by spin or dip coating double metal ethoxide sols. The crystallinity and microstructure of the deposited films were examined by XRD and ТЕМ. Crystallization behavior and resulting microstructure were strongly influenced by the type of substrate. The formation of crystalline LiNbO3 on amorphous carbon was detected at room temperature. Randomly oriented polycrystalline films were obtained on glass at 400°C. Choice of one mole of water per mole of ethoxide generated heteroepitaxial growth of LiNbO3 thin films on (0001) sapphire. Oriented but polycrystalline films were obtained on silicon. The electrical behavior of film on silicon was evaluated in metal-ferroelectric-semiconductor configuration. A dielectric constant of 35 and a dissipation factor of 0.004 was measured at 100 KHz.

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Aluminum Oxide Films for Thermo-Oxidative Protection of Polyimide-Based Composites

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MRS Online Proceedings Library 1993年第1期305卷 191-196页

作者： Larry M. Miller Daniel A. Gulino Department of Chemical Engineering and Condensed Matter and Surface Science Program Ohio University Athens Greece

Polyimide-based composites offer one of the best opportunities to bring the advantages of high modulus-to-density ratio materials to higher temperature applications, such as jet engines. In the present work, thin films (1000 – 2000Å) of aluminum oxide have been deposited by plasma-enhanced chemical vapor deposition from aluminum tri- isopropoxide precursor on polyimide composite substrates. The films were characterized for stoichiometry, thickness uniformity, and adhesion, and their effectiveness in the prevention of thermo-oxidative degradation of the composite at temperatures up to 371 °C has been examined and compared to that provided by other thin film materials. These preliminary results indicate that Al2O3 is not as successful as SiO2 at preventing oxidative degradation, although significant variability in the quality of the polyimide composite substrate makes precise comparison difficult.

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DISPERSION OF TITANIUM-DIOXIDE AGGLOMERATES IN VISCOUS MEDIA (VOL 48, PG 3363, 1993)

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chemical engineering science 1993年第23期48卷 4049-4049页

作者： LEE, YJ FEKE, DL MANAS-ZLOCZOWER, I [a]Department of Macromolecular Science Case Western Reserve University Cleveland OH 44106 U.S.A. [b]Department of Chemical Engineering Case Western Reserve University Cleveland OH 44106 U.S.A.

The dispersion behavior of titanium dioxide agglomerates in viscous media was studied. Under application of shear within a cone-and-plate device, the titanium dioxide agglomerates primarily dispersed by an erosion process in which small fragments separate from the surface. The cohesiveness of unwetted powder was quantified using a compression test method. In some cases, the shear stress necessary to produce erosion was found to be an order of magnitude smaller than the measured cohesivity. Medium infiltration within agglomerates was assessed through observation of penetration of the medium into powder compacts. The kinetics of the erosion process was highly sensitive to the overall porosity of the agglomerates. In the case of high porosity, the erosion rate depends on the speed of medium infiltration within the agglomerate, and the strength of the applied shear stress. A relatively wide size distribution of fragments was observed. For low-porosity agglomerates, the erosion process depends on the magnitude of shear stress, the cohesive strength of the agglomerates, and agglomerate—medium interactions. A narrower distribution of fragments, having smaller mean size, was observed.

关键词： Dispersions

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HYDROCARBON VAPOR DIFFUSION IN INTACT CORE SLEEVES

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GROUND WATER MONITORING AND REMEDIATION 1993年第1期13卷 139-150页

作者： OSTENDORF, DW MOYER, EE XIE, YF RAJAN, RV David W. Ostendorf (Civil Engineering Department University of Massachusetts Amherst MA 01003) is an associate professor in the Environmental Engineering Program of the Civil Engineering Department of the University of Massachusetts at Amherst. His research interests include unconfined aquifer contamination hazardous waste site remediation and analytical modeling of problems in environmental fluid mechanics. Ostendorf is a Registered Professional Engineer in Massachusetts and a member of the American Geophysical Union American Society of Civil Engineers Soil Science Society of America Water Pollution Control Federation and Association of Environmental Engineering Professors as well as the National Ground Water Association. Ellen E. Moyer (Civil Engineering Department University of Massachusetts Amherst MA 01003) is a doctoral candidate in the Environmental Engineering Program of the Civil Engineering Department of the University of Massachusetts at Amherst with an M.S. degree in environmental engineering from that institution. Her research interests include subsurface investigation soil venting bioremediation and analytical modeling of subsurface contamination. She has six years of professional experience managing hazardous waste site investigation and cleanup projects and is a member of the National Ground Water Association and the American Society of Civil Engineers. Yuefeng Xie (Civil Engineering Department University of Massachusetts Amherst MA 01003) is a postdoctoral research associate in the Environmental Engineering Program of the Civil Engineering Department of the University of Massachusetts at Amherst. His research interests include environmental analyses drinking water treatment and the chemical characterization and removal of disinfection by-products. A graduate with a Ph.D. and an M.S. in environmental engineering and a B.S. in chemistry and chemical engineeering from Tsinghua University Beijing China Xie is a member of the American Water Works Association and the Water Poll

The diffusion of 2,2,4-trimethylpentane (TMP) and 2,2,5-trimethylhexane (TMH) vapors out of residually contaminated sandy soil from the U.S. Environmental Protection Agency (EPA) field research site at Traverse City, Michigan, was measured and modeled. The headspace of an intact core sleeve sample was swept with nitrogen gas to simulate the diffusive release of hydrocarbon vapors from residual aviation gasoline in and immediately above the capillary fringe to a soil-venting air flow in the unsaturated zone. The resulting steady-state profile was modeled using existing diffusivity and air porosity estimates in a balance of diffusive flux and a first order source term. The source strength, which was calibrated with the observed flux of 2,2,4-TMP leaving the sleeve, varied with the residual gasoline remaining in the core, but was independent of the headspace sweep flow rate. This finding suggested that lower soil-venting air flow rates were in principle as effective as higher air flow rates in venting LNAPL vapors from contaminated soils. The saturated vapor concentration ratio of 2,2,4-TMP to 2,2,5-TMH decreased from 6.6 to 3.5 over the duration of the experiments in an expression of distillation effects. The vertical profile model was tested against sample port data in four separate experiments for both species, yielding mean errors ranging from 0 to -24 percent in magnitude.

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PERCHL0R0ETHYLENE EXTRACTION DESULFURIZATION OF WEATHERED COALS

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Liquid Fuels Technology 1993年第3-4期11卷 507-527页

作者： Padmakar Vishnubhatt[a] Sunggyu Lee - To whom all correspondence should be directed.[b] Conrad J. Kulik[b] [a] Process Research Center Department of Chemical Engineering The University of Akron Akron OH [b] Fuel Science Program Electric Power Research Institute Palo Alto CA

The perchloroethylene extraction process has proven to be an effective pre- combustion coal desulfurization process which offers a complete process package including wet grinding, organic sulfur removal, pyrite and mineral matter separation, solvent recovery, and byproducts and sulfur recovery. In this paper, coal weatherability was investigated for various Midwestern and Eastern U.S. coals, and its effect on organosulfur extractability by the perchloroethylene process was identified. Both “natural” and “artificial” weathering of these coals were experimentally investigated. A statistically significant difference in the extraction efficiency between fresh and weathered coals vas observed. A strong relation between the extractability and degree of weathering of the coal was established. The results provide a valuable insight into the process engineering of this process.

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Strain Relaxation and Oxide Formation on Annealed W/C Multilayers

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MRS Online Proceedings Library 1993年第1期321卷 215-220页

作者： Geisz, J.F. Phang, Y.H. Kuech, T.F. Lagally, M.G. Cardone, F. Potemski, R.M. Department of Chemical Engineering University of Wisconsin Madison USA MateriaI Science Program University of Wisconsin Madison USA T.J. Watson Research Center IBM Yorktown Heights USA

Tungsten-carbon (W/C) multilayer structures are used as X-ray mirrors and other optical elements. The optical properties of such elements are highly sensitive to changes in strain due to thermal processing. Sensitive curvature measurements were performed on 40Å period W/C multilayer structures on Si substrates using a two beam laser reflection technique. A compressive stress of approximately 1530 MPa was measured in these sputtered multilayer films. Thermal annealing to 500 °C in air and under vacuum resulted in very little strain relaxation in the multilayers but X-ray diffraction data show a slight increase of the multilayer period. Significant strain relaxation, though, was observed when a 400Å W buffer layer was included. Thermal annealing of these samples to 400–500°C resulted in large strain relaxation due to the formation of α-W crystals in the buffer layer. Moderate oxide formation on air annealed samples as measured by SIMS was shown not to be a dominant mechanism of strain relaxation.

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AN OVERVIEW OF IN-SITU AIR SPARGING

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GROUND WATER MONITORING AND REMEDIATION 1993年第4期13卷 127-135页

作者： JOHNSON, RL JOHNSON, PC MCWHORTER, DB HINCHEE, RE GOODMAN, I Dr. Richard L. Johnson is an associate professor in the Department of Environmental Science and Engineering at the Oregon Graduate Institute (P.O. Box 91000 Portland OR 97291). He is also the director of the OGI Center for Groundwater Research and the OGI Large Experimental Aquifer Program. Dr. Paul C. Johnson is a senior research engineer at Shell Development Co. (Westhollow Research Center P.O. Box 1380 Houston TX 77251). Dr. David B. McWhorter is a professor in the Department of Agricultural and Chemical Engineering at Colorado State University (Engineering Research Center Foothills Campus Fort Collins CO 80523). Dr. Robert Hinchee is a research leader in the Environmental Technology Department at Battelle Memorial Institute (505 King Ave. Columbus OH 43201). Iris Goodman is an environmental scientist with the Advanced Monitoring Systems Division at the U.S. EPA Environmental Monitoring Systems Laboratory (P.O. Box 93478 Las Vegas NV 89192).

In situ air sparging (IAS) is becoming a widely used technology for remediating sites contaminated by volatile organic materials such as petroleum hydrocarbons. Published data indicate that the injection of air into subsurface water saturated areas coupled with soil vapor extraction (SVE) can increase removal rates in comparison to SVE alone for cases where hydrocarbons are distributed within the water saturated zone. However, the technology is still in its infancy and has not been subject to adequate research, nor have adequate monitoring methods been employed or even developed. Consequently, most IAS applications are, designed, operated, and monitored based upon the experience of the individual practitioner. The use of in situ air sparging poses risks not generally associated with most practiced remedial technologies: air injection can enhance the undesirable off-site migration of vapors and ground water contamination plumes. Migration of previously immobile liquid hydrocarbons con also be induced. Thus, them is an added incentive to fully understand this technology prior to application. This overview of the current state of the practice of air sparging is a review of available published literature, consultation with practitioners, a range of unpublished data reports, as well as theoretical considerations. Potential strengths and weaknesses of the technology are discussed and recommendations for future investigations given.

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Cobeneficiation of Coals in Perchloroethyleke Extraction Desulfurization

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Fuel science and Technology International 1993年第5-6期11卷 831-843页

作者： Lee, Sunggyu Vishnubhatt, Padmakar Berthinee, Elizabeth A. Process Research Center Department of Chemical Engineering Akron OH 44325-3906 United States Fuel Science Program Electric Power Research Institute Palo Alto CA 94303 United States

The perchloroethylene (PCE) coal refining process has been investigated for its process feasibility, operational reproducibility, organic sulfur selectivity, process efficiency, minimization of residual chlorine by steam stripping and process optimization. It was found that some coals result in a better organosulfur extraction than others. It was also confirmed that the PCE extraction process was a hybrid system of chemical reaction and physical solvation. It was further established that the coals giving a higher organosulfur extraction contain some naturally available ingredients, which promote the extraction process. Coals giving a much lower organosulfur extraction lack these species. This paper focuses on demonstration of the process feasibility of cobeneficiating both types of coals, together. In this novel process, both types of coal are blended together in fixed proportions and subjected to the PCE process. This process of cobeneficiating coals is industrially significant because of its cost effectiveness. It not only removes the organosulfur from one type of coal, but also significantly improves the organosulfur extraction from the other. © 1993, Taylor & Francis Group, LLC. All rights reserved.

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Acyclic diene metathesis (ADMET) polymerization. Synthesis of perfectly linear polyethylene†

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macromolecular Rapid Communications 1993年第10期14卷

作者： John E. O'Gara Kenneth B. Wagener Stephen F. Hahn Department of Chemistry and Center for Macromolecular Science and Engineering University of Florida Gainesville Florida 32611 U.S.A. Advanced Polymeric Systems Laboratory Central Research and Development The Dow Chemical Company Midland MI 48674 U. S. A.

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EPAS APPROACH TO VADOSE ZONE MONITORING AT RCRA FACILITIES

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GROUND WATER MONITORING AND REMEDIATION 1993年第1期13卷 151-158页

作者： DURANT, ND MYERS, VB ECCLES, LA Washington D.C. 20460) has worked as an environmental scientist in the RCRA corrective action program at EPA since 1989. After graduating from Colgate University in 1987 Durant worked for GeoTrans Inc. conducting hydrogeologic investigations at numerous waste disposal sites throughout the northeastern United States. At present Durant is pursuing an M.S. degree in environmental science from The Johns Hopkins University. His research is focused on enhancing in situ biodegradation of aromatic organic compounds in the subsurface. Washington D. C. 20460) graduated from The Johns Hopkins University in 1972 with a B.A. degree in natural sciences. Myers received a Ph.D. in oceanography from Florida State University in 1977. During 1978 he held a post doctoral fellowship at University of Florida in the Department of Environmental Engineering and Science. From 1979 to 1983 Myers was employed by the Florida Department of Environmental Regulation where he worked on environmental restoration projects. Since 1984 Myers has worked at EPA managing RCRA ground water monitoring and corrective action programs. Lawrence A. Eccles (U.S. Environmental Protection Agency Environmental Monitoring Systems Laboratory P.O. Box 93478 Las Vegas NV 89193–3478) is a hydrologist with the EPA Environmental Monitoring Systems Research Laboratory in Las Vegas Nevada. Eccles is responsible for the development of vadose zone and in situ monitoring techniques and guidelines. After graduating from Monmouth College with a B.S. degree in chemistry Eccles performed graduate work in chemical engineering at New Mexico State University. He received formal training in hydrology in 1969 from the U.S. Geological Survey in Denver and worked with that agency before joining EPA at Las Vegas in 1984. One of his co-authored articles was chosen for the Best Paper Award by the journal Ground Water in 1975 and another was the subject of a cover story for Water Well Journal in 1977.

The U.S. Environmental Protection Agency (EPA) recently proposed to amend federal regulations to require vadose zone monitoring at certain hazardous waste facilities. To support this proposal, EPA evaluated previous policy on vadose zone monitoring and examined advances in vadose zone monitoring technology. Changes in EPA vadose zone monitoring policy were driven by demonstrated advances in the available monitoring technology and improvements in understanding of vadose zone processes. When used under the appropriate conditions, currently available direct and indirect monitoring methods can effectively detect contamination that may leak from hazardous waste facilities into the vadose zone. Direct techniques examined include soil-core monitoring and soil-pore liquid monitoring. Indirect techniques examined include soil-gas monitoring, neutron moderation, complex resistivity, ground-penetrating radar, and electrical resistivity. Properly designed vadose zone monitoring networks can act as a complement to saturated zone monitoring networks at numerous hazardous waste facilities. At certain facilities, particularly those in arid climates where the saturated zone is relatively deep, effective vadose zone monitoring may allow a reduction in the scope of saturated zone monitoring programs.

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