bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Use of Controlled Source Audio Magnetotellurics (CSAMT) to Delineate Zones of Ground-Water Contamination—A Case History
Authors: Tinlin RM , Hughes LJ , Roger Anzzolin A 
Published: February 2009

A significant potential for the pollution of fresh-water aquifers exists due to oilfield waterflood operations. The sources of potential pollution are surface spills, a lack of mechanical integrity of injection wells, and improperly plugged wells which are in communication with the injection zone. Surface spills are relatively easy to detect and control. Procedures for checking the mechanical integrity of a properly constructed injection well are available. Making a determination in the absence of good records as to whether or not a well is improperly plugged, providing a conduit for the vertical migration of formation brines from the production zone to shallower fresh-water aquifers, is very difficult.
Electrical surface geophysical methods offer considerable promise in detecting the movement of formation brines into fresh-water aquifers, through improperly abandoned or plugged wells.
An electrical surface geophysical technique, Controlled Source Audio-Frequency Magnetotellurics (CSAMT) has been applied to locate the presence of anomalies resulting from the upward movement of formation brines through improperly plugged wells. The primary objective in a CSAMT survey is to provide apparent resistivity and the phase angle between the electric and magnetic fields over a prospect area. CSAMT has the advantages of excellent lateral resolution, good depth penetration (a kilometre or more) and is relatively inexpensive. The frequency and resistivity of the subsurface control the depth of penetration. The lower the frequency, the deeper the penetration.
A CSAMT survey was run in an oil-producing field in east central Oklahoma, which is currently on waterflood and has many abandoned and apparently improperly plugged wells. The water in the Vamoosa aquifer underlying the study area has a high chloride content. The objective of running the CSAMT survey was to locate suspected low-resistivity anomalies due to formation brines in the vicinity of improperly plugged wells and to attempt to map their extent.
Adsorption of Selected Organic Contaminants onto Possible Well Casing Materials
Authors: JN Jones , GD Miller 
Published: February 2009

In order to assess and monitor the impact of man's activities on ground-water quality, the nature, concentration, and behavior of pollutants in the subsurface must be determined. To do this, it is necessary to collect representative samples of water from the subsurface environment. Ideally, the material chosen as a well casing for monitoring wells should not add or remove constituents from the ground-water sample collected.
The objective of this study was to determine if specific trace organics adsorb and subsequently leach from various well casing materials upon exposure to those specific pollutants for specified periods of time. The types of well casings studied included thermoplastics, stainless steel and fluoroplastics. Of the pollutants studied, only 4-nitrophenol and 2,4,6-trichlorophenol showed appreciable adsorption for all well casing materials. Subsequent leaching of pollutants was not observed in any measurable quantities.
Recent Development of Downhole Water Samplers for Trace Organics
Authors: Ficken JH 
Published: February 2009

Studies concerning the movement and fate of organic chemicals, including hazardous substances, in ground water have underscored the need to use boreholes to obtain samples of ground water that are neither contaminated with foreign materials nor diluted with water from other sources. Additionally, the water samples need to be taken in a manner that prevents the escape of volatile substances. The samples need to be kept close to the original state while in shipment to the water quality laboratory and at the laboratory where the water must be removed from the sample holders without the escape of volatiles or reaction with the air. Within the past year the U.S. Geological Survey has identified its needs for data concerning organics in ground water, and established design criteria for the development of prototype samplers. Certain essential sampler design criteria are: The sampler must go down a 5.1-cm (2 in.) diameter well; the practical sampling depth is at least 61 m (200 ft); the sample holder must be flushed before a sample is taken; and the sample must be kept at the same hydrostatic pressure as when collected.
The Survey is developing prototype samplers using the designated design criteria—a piston sampler operating from a well-logging head, a pumping sampler using a commercial downhole gear pump, a hand-pump sampler, and two electric motor-driven samplers using logging heads. These samplers flush a sample cartridge with the water to be sampled and finally seal the sample prior to being brought to the surface. Later, a design criterion was added that all flush water be removed from the well. New design schemes were drafted that accomplished that requirement. One of the design schemes was a manual sampler which uses a downhole reservoir to collect the flush water. Other design schemes have been envisioned but were found not to be practical. A special sample cartridge that will fit these samplers has been developed to allow removal of the water under pressure. This design helps prevent the escape of volatile substances from the water sample. Fabrication materials include stainless steels, fluoroelastomers, and other fluorinated plastics.
Long-Term Permeability Tests Using Leachate on a Compacted Clayey Liner Material
Authors: Fang H-Y , Evans JC 
Published: February 2009

This paper presents the results of laboratory tests on a compacted clayey liner material using landfill leachate. Laboratory permeability tests were conducted with continuous permeation for a period from three to to six months in duration in specially designed traxial cell permeameters. The soil samples were obtained from a borrow pit in eastern Pennsylvania and proposed for use as a compacted liner material. Routine soil tests, including Atterberg Limits, gradation, compressive strength, and compaction tests were conducted on samples exposed to both tap water and leachate. Limited tests were conducted on bentonite-clay mixtures to illustrate the behavioral difference between high-swelling and non-high-swelling clays.
It was found that permeation of the clayey liner material with landfill leachate did not significantly alter permeability of the material. Further, the physical properties remained relatively unchanged. In contrast, test results conducted on bentonite-clay mixtures resulted in more significant changes. It is concluded that leachate permeation of natural silty clays of low activity, such as the material investigated herein, can result in inconsequential change in engineering properties. In contrast, leachate permeation of a high-swelling sodium montmorillonitic soil could result in significant changes in physical and engineering properties of the soil.
A Geologic and Flow-System-Based Rationale for Ground-Water Sampling
Authors: Urban JB , Gburek WJ 
Published: February 2009

Representative measurements of ground water require a sampling protocol based on the physical and hydraulic properties of the geologic materials. Measurements must be made within the context of the site and areal ground-water flow systems. A multizone geologic system in east-central Pennsylvania is used as an example of instrumentation by geologic and hydrologic criteria. Geology is that of a weathered, fractured, sedimentary rock mantle overlying deeper, less fractured, sedimentary rock strata.
The focus of this paper is on describing the domain of and controls on ground-water flow within the shallow (&lt;15 m) and deep (15 to 100 m) fracture systems. A systematic approach, using commonly available information, identifies the areal extent, depth, hydraulic conductivity distribution, and paths of ground-water flow in the two systems. This approach was tested within a 7.4-km2 watershed and at stream-valley cross sections. The findings indicate that ground-water quality distribution is accurately portrayed in both settings if the sampling scheme is based on geologic and flow system controls. Ground-water sampling wells must be located, and their data interpreted, by grouping according to geology and the ground-water flow system elements of recharge, lateral flow, and discharge zones.
Basic Questions in Fatigue: Volume I
Authors: Fong JT , Wei RP , Fields RJ , Gangloff RP 
Published: February 2009

Description
Volume I contains introductory remarks and addresses the questions of nucleation of fatigue damage in single crystals and polycrystals, with principal emphasis on the observation of damage at the microstructural level. Other sections deal primarily with the role of mechanical variables on fatigue crack growth in ferrous and nonferrous alloys, and focus attention at the continuum level.
Volume II contains 3 sections on more complicated topics of research where the state of knowledge is in the formative stage. The first section considers complex interactions associated with combined fatigue and creep damage. The next section deals with the questions of environmental effects. The last section contains the only papers that address fatigue of nonmetals.
Adhesively Bonded Joints: Testing, Analysis, and Design
Authors: Johnson WS 
Published: February 2009

Description
Twenty-one papers present the latest advances in the understanding of mechanical behavior of adhesives. Their focus is on aircraft and naval applications. The mechanical testing section discusses techniques and specimen designs for determining tensile, shear, and mixed-mode properties of adhesives. Papers on stress analysis consider both analytical and experimental methods to analyze the stress in an adhesively bonded joint. In the section on failure mechanisms examples are presented for several types of adherents and specimen geometries. The final section considers design and durability of bonded joints.
Mathematical Modeling of Fires
Authors: Mehaffey JR 
Published: February 2009

Description
Nine papers are featured. Two review the role of ASTM in fire modeling and describe ASTM E 906. Other papers present: a new simple model of fire growth in a compartment; a model of hydrogen chloride and decay; a fire loss modeling code for industrial facilities; characteristic times for describing forced-ventilation enclosure fires; optical and gravimetric soot measuring techniques for the cone calorimeter; a computer model for the heat release rate of wood; and a benchmark compartment fire model computer code.
Nonlinear Fracture Mechanics: Volume II Elastic-Plastic Fracture
Authors: Landes JD , Saxena A , Merkle JG 
Published: February 2009

Description
Two volume set: Volume 1 — Nonlinear Fracture Mechanics: Time Dependent Fracture. Volume 2 — Nonlinear Fracture Mechanics: Elastic-Plastic Fracture
STP 995 contains recent work on traditional elastic plastic fracture mechanics as well newer areas, such as time dependent fracture mechanics and dynamic fracture. Papers discuss analytical considerations, experimental methods, and applications. Third in a series of ASTM books on nonlinear fracture mechanics.
Terahertz Ellipsometry Using Electron-Beam Based Sources
Authors: Hofmann Tino , Herzinger Craig M. , Schade Ulrich , Mross Michael , Woollam John A. , Schubert Mathias 
Published: February 2009

AbstractThe precise determination of materials' optical constants in the THz frequency domain is an important new challenge in basic research and is crucial for novel technological applications. Spectroscopic ellipsometry is known as a vital tool for the determination of the materials' dielectric function including its anisotropy. However, ellipsometric measurements at very long wavelengths are difficult due to the lack of reliable sources of sufficient intensity and brilliance. Here we report on our recent advances to use ellipsometry in combination with different electron beam based sources in order to in investigate condensed matter samples in the frequency range from 0.1 to 8 THz. We successfully employ terahertz radiation emitted from two different tunable desktop sources (Smith-Purcell-effect source and a backward wave oscillator) in a polarizer-sample-analyzer ellipsometer scheme. We discuss and present THz range physical material properties due to bound and unbound charge resonances in semiconducting materials. This research will provide important understanding of optical properties for novel materials, inspire new designs, and accelerate development of optical Terahertz devices.
Low Resistance Ohmic Contacts Formation and Mechanism of Current Transport Through p-GaN and p-AlGaN
Authors: Chary Indra , Borisov Boris , Kuryatkov Vladimir , Kudryavtsev Yuriy , Asomoza R , Nikishin Sergey A , Holtz Mark 
Published: February 2009

AbstractWe report the influence of surface treatment, annealing temperature and metal bilayer thickness on the specific contact resistance (&#961;c) of Au/Ni ohmic contacts to p-GaN and p-AlGaN. Ohmic contact on p-GaN with a hole concentration of 6.5 x 1017 cm-3, shows the lowest &#961;c of ˜9.2 x 10-6 Ω cm2, when GaN was treated in HCl:H2O (3:1) solution before metal deposition and annealed at 500°C for 10 minutes in 90% N2 and 0% O2 atmosphere. Similar procedure applied on p-AlxGa1-xN (x = 5-7%), with a hole concentration of 2.3 x 1017 cm-3, yields a &#961;c of 1.8 x 10-4 Ω cm2. An increase is observed in &#961;c when Mg doping exceeds 4 x 1019 cm-3 in both p-GaN and p-AlGaN. This is attributed to Mg self compensation. This increase is more pronounced in AlGaN which we attribute to the presence of residual native aluminum oxides.
Nucleation and Stochiometry Dependence of Rutile-TiO2(001)/GaN(0001) Thin Films Grown by Plasma-Assisted Molecular Beam Epitaxy
Authors: Constantin Costel , sun kai , Feenstra Randall M 
Published: February 2009

AbstractIn this work we explore both the initial nucleation and the stoichiometry of rutile-TiO2(001) grown on wurtzite GaN(0001) by radio-frequency O2-plasma molecular beam epitaxy. Two studies are performed; in the first, the dependence of the growth on stoichiometry (Ti-rich and O-rich) is observed using reflection high energy electron diffraction and high resolution transmission electron microscopy. In the second study we examine the effect of different initial nucleation surfaces (i.e. Ga-terminated and excess Ga-terminated) and compare the interfaces and bulk crystallinity of the TiO2(001) films grown on top of these surfaces. High-resolution transmission electron microscopy and x-ray diffraction measurements show a better interface for TiO2(001)/Ga-terminated - GaN(0001) as compared to the TiO2(001)/excess Ga-terminated- GaN(0001).
Magnetic Resonance Study of Non-Equivalent Centers Created by 4f-Ions in Congruent and Stoichiometric Lithium Niobate
Authors: Malovichko Galina , Grachev Valentin , Jorgensen Jonathan , Meyer Martin , Munro Mark , Todt Benjamin , Vrable Ian , Kokanyan Edward , Bratus Viktor , Okulov Sergei 
Published: February 2009

AbstractLithium Niobate doped with 4f-ions is of great interest for both fundamental science and advanced applications including high efficiency lasers with frequency conversion, elements for an all-optical telecommunication network and quantum cryptography. Our study has shown that 4f-ions create an unexpected variety of completely different non-equivalent centers in both stoichiometric and lithium deficient congruent crystals. Dominant Nd1 and Yb1 centers have C3 point symmetry (axial center), whereas all Er and most other Nd and Yb centers have the lowest C1 symmetry. Distant defects create small distortions of the crystal field at the impurity site, which cause line broadening, but do not change the C3 symmetry of observed EPR spectra. Defects in the near neighborhood can lower center symmetry from C3 to C1. We concluded that Nd1 has distant charge compensation, whereas the charge excess in low-symmetry Nd(Li) centers is compensated by near lithium or niobium vacancies. Since no axial centers were found for Er, models with cation vacancies can not describe our experimental data. The dominant axial Yb1 center has no defects in its surrounding. One axial and one low-symmetry Yb centers are self compensating Yb(Li)-Yb(Nb) pairs. Six other centers are different complexes of Yb3+ and intrinsic defects. Obtained data can be used for defect engineering for tailoring properties of photonic materials.
Optical Materials for Medical Applications: an Overview of Ultrafast Emitting Oxidic Pr3+ Scintillating Materials
Authors: Ronda Cees , Gondek Joanna , Goirand Emilie , Jüstel Thomas , Bettinelli Marco , Meijerink Andries 
Published: February 2009

AbstractThis paper describes an investigation towards very fast emitting oxidic luminescent materials doped with Pr3+. Such materials have the potential to be applied as scintillators in Positron Emission Tomography.
Low Temperature Transparent Nanoplatelet Hybrid Gas Barrier Coating Materials via Sol-gel Process
Authors: Asuka Masahiro , Sigmund Wolfgang Michael 
Published: February 2009

AbstractA novel hybrid coating based on a combination of nanoparticles, sol-gel and organic chemistry is reported. It can be applied to a large variety of surfaces even at low processing temperatures, and it cures below 150°C. Furthermore, fabrication of the hybrid films on polymer sheets can be done under ambient conditions. No vacuum techniques are required. Boehmite nanoplatelet composite hybrid organic/inorganic coating materials have been successfully prepared via this approach. The coating process involves the dispersion of boehmite nanoparticles that are suspended without significant agglomeration. 3-glycidoxy propyl trimethoxy silane (GPTMS) was adopted as dispersant for the nanoplatelets and functions also as a network former. This induces flexibility in the hybrid film due to the organic functional groups. Transparent cured coatings from flexible to brittle were obtained from a single coating step with thicknesses in excess of 10 μm depending on the ratio of the inorganic/organic reagents and their concentrations. Barrier coatings with more than 60wt% ceramic nanoplatelets were achieved, yet they still display transparency of more than 95% to visible light with no cracks or other discernable defects. Several substrates have been successfully tested including poly (ethylene terephthalate) (PET). Moreover water permeability for cured coated PET films is reduced to less than 0.01 g/m2/d. Excellent mechanical properties such as flexibility and hardness are demonstrated by nanoindentation and scratch tests.
Electrical Response of Polycrystalline Silicon Thin Film Transistor on Steel Foil under Mechanical Strain
Authors: Kuo Po-Chin , Jamshidi-Roudbari Abbas , Hatalis Miltiadis K 
Published: February 2009

AbstractThis work investigates the effects of mechanical strain on electrical characteristics of polycrystalline thin film transistors (poly-Si TFTs). Poly-Si TFTs were fabricated on steel foil substrate and characterized under the strain ranging from -1.2% to 1.1% induced by bending. The electron mobility increased under tensile and decreased under compressive strain while that of the hole exhibited an opposite trend. For p-channel TFTs the normalized threshold voltage and subthreshold slope were a function of strain. In both n- and p-channel TFTs the off current decreased under tensile while it increased under compressive strain. The observed mobility trends in poly-Si TFTs are similar to those reported in single crystalline silicon devices.
A Thermodynamic Approach on the Effect of Salt Concentration on Swelling Pressure of Water-saturated Bentonite
Authors: Sato Haruo 
Published: February 2009

AbstractThe effect of salt concentration on swelling pressure of water-saturated bentonite was modelled based on the thermodynamic data of water at montmorillonite surface and of water in solutions of various salinities coming in contact with the montmorillonite. Activities of water at montmorillonite surface were obtained as a function of water content and temperature at montmorillonite densities of 0.6 and 0.9Mg/m3 by a vapor pressure method, and the relative partial molar Gibbs free energies (dGw) were determined. Water affected from the montmorillonite surface was estimated to be almost all interlayer water. Swelling pressure vs. montmorillonite partial density was estimated for solutions of various salinities and compared to data measured for various montmorillonite contents and different silica sand contents of bentonites. The calculated swelling pressure clearly decreased with increasing salinity. The effect of salinity on swelling pressure was not clear in the measured data and was within the range of the scattering in the measured data. This cause is presumed to be due to the increase of the ionic strength of porewater by dissolution of soluble minerals in the bentonite.
Migration Behavior of Bentonite Colloids through a Fractured Rock
Authors: Kuno Yoshio , Sasamoto Hiroshi 
Published: February 2009

AbstractBentonite colloids released into groundwater from the buffer in a geological repository for high-level radioactive waste may influence the migration of radioactive elements in fractures of the host rock. In the present study, column experiments were carried out to investigate the migration behavior of bentonite colloids in artificially fractured granite. The objective of the study is to determine whether the colloids are filtered by the fracture, considering the effects of the fracture length and the ionic strength of transporting solutions. Results indicate that bentonite colloids are not filtered if the transporting solution is dilute (i.e., distilled water or 10-4 M NaCl solution). This is evidenced by the observed tendency for normalized colloid concentrations in the column effluent (C/C0) to rapidly approach 1. An initial increase in the breakthrough curves is also observed at early stages of migration experiments involving more concentrated solutions (10-3 M NaCl solution), but the curves later evolve to an approximate steady state with C/C0 < 1. The amount of filtered colloids tends to increase with increasing fracture length. These results suggest that bentonite colloids can be filtered by interactions between the colloids and fracture surfaces, and that these interactions are affected by the ionic strength of the transporting solution. This migration behavior is simulated by a model of colloid migration, taking into consideration the effects of colloid filtration by fracture surfaces. The information on the filtration of bentonite colloids would contribute to a more realistic assessment of colloid effects on radionuclide migration.