Descreening of Field Effect in Electrically Gated Nanopores

This modeling work investigates the electrical modulation characteristics of field-effect gated nanopores. Highly nonlinear current modulations are observed in nanopores with non-overlapping electric double layers, including those with pore diameters 100 times the Debye screening length. We attribute this extended field-effect gating to a descreening effect, i.e. the counter-ions do not fully relax to screen the gating potential due to the presence of strong ionic transport

A CAD-oriented modeling approach of frequency-dependent behavior of substrate noise coupling for mixed-signal IC design

A simple, efficient CAD-oriented equivalent circuit modeling approach of frequency-dependent behavior of substrate noise coupling is presented. It is shown that the substrate exhibits significant frequency-dependent characteristics for high frequency applications using epitaxial layers on a highly doped substrate. Using the proposed modeling approach, circuit topographies consisting of only ideal lumped circuit elements can be synthesized to accurately represent the frequency response using y-parameters. The proposed model is well-suited for use in standard circuit simulators. The extracted model is shown to be in good agreement with rigorous 3D device simulation results. 1

Analysis of existing mathematics textbooks for use in secondary schools.

Thesis (Ed.M.)--Boston University Thesis (M.A.)--Boston Universit

Effect of Electro-Diffusion Current Flow on Electrostatic Screening in Aqueous Pores

A numerical study within the framework of the Poisson-Nernst-Planck equations is conducted to investigate electrostatic screening of charged bio-molecules within synthetic pores having diameters of at least 10 Debye lengths. We show that with external biases, the bio-molecule charge is only partially screened due to the presence of electrodiffusion current flow. This is considerably different from the equilibrium Debye-Huckel screening behavior and will result in long-range electrostatic interactions. The potential application to direct bio-molecule charge sensing is also discussed

Powerful alliances in graphs

AbstractFor a graph G=(V,E), a non-empty set S⊆V is a defensive alliance if for every vertex v in S, v has at most one more neighbor in V−S than it has in S, and S is an offensive alliance if for every v∈V−S that has a neighbor in S, v has more neighbors in S than in V−S. A powerful alliance is both defensive and offensive. We initiate the study of powerful alliances in graphs

Geologic Analysis of Primary and Secondary Tight Gas Sand Objectives, Phase C

Previous assessments of blanket-geometry tight gas sandstones led to the selection of the Travis Peak Formation of the East Texas and North Louisiana Basins and the Corcoran and Cozzette Sandstones of the Piceance Creek Basin as major research objectives. The anticipated outcomes of this study include increased availability of tight gas resources and advancements in technology with high transferability. The work reported here encompasses all aspects of the depositional systems and reservoir geology of these units as fundamental components of resource characterization, with an emphasis on understanding controls on reservoir facies distribution and their relevance to low-permeability reservoir development. Six lithofacies of the Travis Peak (Hosston) Formation in East Texas and North Louisiana have been identified using electric logs. These facies comprise sand-rich fluvial-deltaic, silt-rich delta-front, clay- and carbonate-rich shelf, carbonate reef, and clay-rich open marine facies. The most well-developed facies in the East Texas area are the fluvial-deltaic and delta-front facies. Travis Peak rocks from the Clayton Williams #11 Sam Hughes well, Panola County, Texas, were primarily deposited in a fluvial environment within a coastal plain setting. Porosity and permeability control in the clean sandstones are primarily attributed to quartz overgrowths, chlorite cement, and solid organic matter, with approximately half of the remaining porosity being secondary, resulting from framework grain dissolution. Studies of Travis Peak gas production at Pinehill Southeast and Percy-Wheeler fields indicate an average permeability-thickness product of about 10 md-ft, with a range of 0.7 to 35 md-ft, indicating dry gas reservoirs. Well logs, core, and mud logs from Chapel Hill field in Smith County, Texas, were examined in preparation for a complete cooperative well program in the ARCO #11 Phillips well on the western margin of that field. Field studies of Corcoran-Cozzette Sandstones near Grand Junction, Colorado, suggest that the depositional environments of the Corcoran evolved from marine upper shoreface to non-marine, while the Cozzette sequence evolved from lower to upper shoreface. Porosity and water saturation calculations have been conducted by computer for seven Corcoran and Cozzette depositional units. A comparison of calculated water saturation with core-derived porosity and permeability indicates a fair to very good correlation of reservoir properties with clay content measured by gamma-ray log.Bureau of Economic Geolog

Geology of the Lower Cretaceous Travis Peak Formation, East Texas: Characterization of a Tight Gas SandStone

Since 1982, the Gas Research Institute (GRI) Tight Gas Sands Project has supported geological investigations designed to develop knowledge necessary to efficiently produce low-permeability, gas-bearing sandstones. As part of that program, the Bureau of Economic Geology has conducted research on low-permeability sandstone in the Lower Cretaceous Travis Peak (Hosston) Formation in East Texas. The first phase of the study, which lasted from 1983 until 1986, involved extensive collection of core and production data in seven cooperative wells. Information gained from the cooperative wells, combined with geologic characterization of the Travis Peak throughout the study area, led to the drilling by GRI of three Staged Field Experiment (SFE) wells between 1986 and 1988. The SFE wells were drilled and completed by GRI specifically for the purpose of research on low-permeability gas reservoirs. This report summarizes the results of the geologic studies of the Travis Peak Formation, and it focuses on the contribution of geology to evaluation and completion of tight gas sandstone wells.Bureau of Economic Geolog