Digest of Hydraulic Fracturing Cases

As U.S. coal exports increase and new infrastructure is proposed to improve access to markets in Asia, controversy has arisen regarding the scope of environmental review that should be carried out by government. In particular, there is significant disagreement as to whether the end-use of exported coal and the emissions generated by its combustion fall within the scope of environmental review under the National Environmental Policy Act of 1969 (NEPA). This paper considers this issue, examining the requirements of NEPA and its implementing regulations, as well as current practice by Federal agencies

High-Q impurity photon states bounded by a photonic-band-pseudogap in an optically-thick photonic-crystal slab

We show that, taking a two-dimensional photonic-crystal slab system as an example, surprisingly high quality factors (Q) over 10^5 are achievable, even in the absence of a rigorous photonic-band-gap. We find that the density of in-plane Bloch modes can be controlled by creating additional photon feedback from a finite-size photonic-crystal boundary that serves as a low-Q resonator. This mechanism enables significant reduction in the coupling strength between the bound state and the extended Bloch modes by more than a factor of 40.Comment: 5 pages, 4 figure

Microscaled and nanoscaled platinum sensors

We show small and robust platinum resistive heaters and thermometers that are defined by microlithography on silicon substrates. These devices can be used for a wide range of applications, including thermal sensor arrays, programmable thermal sources, and even incandescent light emitters. To explore the miniaturization of such devices, we have developed microscaled and nanoscaled platinum resistor arrays with wire widths as small as 75 nm, fabricated lithographically to provide highly localized heating and accurate resistance (and hence temperature) measurements. We present some of these potential applications of microfabricated platinum resistors in sensing and spectroscopy

Coulomb blockade in vertical, bandgap engineered silicon nanopillars

Vertically oriented, bandgap engineered silicon double tunnel junction nanopillars were fabricated and electrically addressed. The devices were tested at liquid nitrogen and room temperatures. Distinctive staircase steps in current were observed at cryogenic temperatures indicative of the Coulomb blockade effect present in asymmetric double tunnel junction structures. These features disappeared when the device was measured at room temperature

Size tunable visible and near-infrared photoluminescence from vertically etched silicon quantum dots

Corrugated etching techniques were used to fabricate size-tunable silicon quantum dots that luminesce under photoexcitation, tunable over the visible and near infrared. By using the fidelity of lithographic patterning and strain limited, self-terminating oxidation, uniform arrays of pillar containing stacked quantum dots as small as 2 nm were patterned. Furthermore, an array of pillars, with multiple similar sized quantum dots on each pillar, was fabricated and tested. The photoluminescence displayed a multiple, closely peaked emission spectra corresponding to quantum dots with a narrow size distribution. Similar structures can provide quantum confinement effects for future nanophotonic and nanoelectronic devices

Structural basis of DNA binding complexes

The nucleosome remodeling and deacetylase (NuRD) complex is an abundant deacetylase complex, which couples histone deacetylation and chromatin remodeling ATPase activities, and has a broad cellular and tissue distribution. Although the working model of how this complex forms and functions is not well known, we have demonstrated that the coiled-coil interaction between two proteins (MBD2 and p66α) is critical for DNA methylation dependent gene silencing in vivo. Chapter one: ‘Unique features of the anti-parallel, heterodimeric coiled-coil interaction between methyl-cytosine binding domain 2 (MBD2) homologues and p66α dictate high affinity binding’ describes this unique coiled coil interaction. Coiled-coils were studied using a variety of biophysical techniques including analytical ultracentrifugation (AUC), isothermal titration calorimetry (ITC) and circular dichroism (CD). Results were compared across homologues and mutation studies were carried out to test our hypotheses. The studies reported in this chapter add to our understanding of coiled-coil interaction and thereby facilitate development of small peptide based drugs which target such interactions in nature.A number of proteins have been identified in humans that specifically bind to methylated CpG via a methyl binding domain (MBD). The human genome encodes at least five MBD proteins: MeCP2 and MBD1 through MBD4, which are homologous in their methyl binding domains but not many similarities are seen outside the MBD. Out of the five MBDs, MBD4 has a c-terminal glycosylase domain through which it recognizes mCpG.TpG mismatch and is important for base excision repair system. Chapter two: ‘Dynamic behavior of MBD4 in methylated DNA recognition’ focuses on MBD4 and its preference for DNA methylation mark. Techniques of surface plasmon resonance (SPR), nuclear magnetic resonance (NMR) spectroscopy are used to study binding affinity for variations of methylated DNA mark. Chemical exchange studies are used to demonstrate how MBD4 scans for methylation mark and these studies have added a new dimension to our understanding of how MBD proteins ‘read’ DNA methylation marks. Chapter three: ‘Solving the solution structure of MBD domain of MBD4 on methylated DNA by NMR’ describes a process of structure determination using NMR spectroscopy. The focus of this chapter is not on developing a new technique but rather on using current resources to solve a protein structure, which can be used to further understand our biological system. Here, I have discussed the workflow used to determine a final three-dimensional structure starting from sample preparation, data collection, data analysis to structure calculation

Scalable Method for the Fabrication and Testing of Glass-Filled, Three-Dimensionally Sculpted Extraordinary Transmission Apertures

This Letter features a new, scalable fabrication method and experimental characterization of glass-filled apertures exhibiting extraordinary transmission. These apertures are fabricated with sizes, aspect ratios, shapes, and side-wall profiles previously impossible to create. The fabrication method presented utilizes top-down lithography to etch silicon nanostructures. These nanostructures are oxidized to provide a transparent template for the deposition of a plasmonic metal. Gold is deposited around these structures, reflowed, and the surface is planarized. Finally, a window is etched through the substrate to provide optical access. Among the structures created and tested are apertures with height to diameter aspect ratios of 8:1, constructed with rectangular, square, cruciform, and coupled cross sections, with tunable polarization sensitivity and displaying unique properties based on their sculpted side-wall shape. Transmission data from these aperture arrays is collected and compared to examine the role of spacing, size, and shape on their overall spectral response. The structures this Letter describes can have a variety of novel applications from the creation of new types of light sources to massively multiplexed biosensors to subdiffraction limit imaging techniques

NEPA and Downstream Greenhouse Gas Emissions of U.S. Coal Exports

As U.S. coal exports increase and new infrastructure is proposed to improve access to burgeoning markets in Asia, controversy has arisen regarding the scope of environmental review that should be carried out by government. In particular, there is significant disagreement as to whether the end-use of exported coal and the emissions generated by its combustion fall within the scope of environmental review. The National Environmental Policy Act of 1969 (NEPA) sets out an assessment process that applies to many Federal agency actions relating to coal export, including the grant of leases for coal mines, approval for new railway construction and the grant of permits for coal export terminals. Under NEPA, an environmental impact statement (EIS) must be prepared for any major Federal action significantly affecting the quality of the human environment. This includes direct, indirect and cumulative effects. The question of which indirect consequences of an action should be considered, and how far the review extends into upstream or downstream effects, is essentially a question of causation. Where a downstream event, such as the export and end-use of coal, is a reasonably foreseeable consequence of an action or there is a reasonably close causal relationship, then those downstream effects are within the scope of NEPA review. The greatest challenge in evaluating greenhouse gas (GHG) emissions under NEPA is determining when they are likely to have a “significant” impact on the environment. Climate change is a highly complex problem, and the GHGs emitted by any single project are unlikely to have a substantial impact on global atmospheric concentrations of carbon dioxide. Thus, agencies need to consider the cumulative impacts of these projects -- as required by NEPA -- and their relative contribution to climate change

Three-dimensional etching of silicon for the fabrication of low-dimensional and suspended devices

In order to expand the use of nanoscaled silicon structures we present a new etching method that allows us to shape silicon with sub-10 nm precision. This top-down, CMOS compatible etching scheme allows us to fabricate silicon devices with quantum behavior without relying on difficult lateral lithography. We utilize this novel etching process to create quantum dots, quantum wires, vertical transistors and ultra-high-aspect ratio structures. We believe that this etching technique will have broad and significant impacts and applications in nano-photonics, bio-sensing, and nano-electronics