The effects of adding Class F fly ash as a filler to a commercially available polyurethane grout for use in compaction grouting was investigated. The purpose of the physical model study was to determine the range of soil densification that can be obtained by using polyurethane in compaction grouting. Two CPT sites, diagonally opposite were used to determine the soil density (Shethji 2004). To confirm that the grout densified the soil, not filling the voids, a Plexiglas barrier was installed into the sand chamber with vertical chalk lines along the carrier. The grout will be inserted and the effect on the lines measured. b) Wet-Dry Cycle Test: The water absorption during wet and dry cycles for foamed grout was determined by measuring changes in both weight and volume. These measurements were taken while immersing the specimen in water on regular cycles of two weeks, one week for wetting and one week for drying. 4. Results and Discussion a) Sand Chamber Test Results The grout bulbs generated had similar shapes and were consistent with the bulbs generated by conventional compaction grouts. It can be observed that expansive compaction grouting performs similar to injection compaction grouting. The relative density improvement was from 65% to 79% for 10/50/10 (Figure 1 and 2). The split chamber test resulted in a 5 inch radius. b) Wet-Dry Cycle Tests Sample 10/50/10 average swell was 28% with an average shrink of 0%. Sample 10/30/30 shrank
Microreplicated CMP pad is applied to W and Co buff CMP steps for topography and WiDNU reduction of RMG and MOL metallization. This new pad exhibits stable rates and low defectivity over extended life time without the need for diamond conditioner. It also demonstrates reduction in topography built-up at device level and die level, leading to remarkable reduction in topo-related defects for MOL local interconnects.
The application of solid-state (SS) nanopore devices to single-molecule nucleic acid sequencing has been challenging. Thus, the early successes in applying SS nanopore devices to the more difficult class of biopolymer, glycosaminoglycans (GAGs), have been surprising, motivating us to examine the potential use of an SS nanopore to analyze synthetic heparan sulfate GAG chains of controlled composition and sequence prepared through a promising, recently developed chemoenzymatic route. A minimal representation of the nanopore data, using only signal magnitude and duration, revealed, by eye and image recognition algorithms, clear differences between the signals generated by four synthetic GAGs. By subsequent machine learning, it was possible to determine disaccharide and even monosaccharide composition of these four synthetic GAGs using as few as 500 events, corresponding to a zeptomole of sample. These data suggest that ultrasensitive GAG analysis may be possible using SS nanopore detection and well-characterized molecular training sets.
The work presented in this thesis covers advancements made in carbohydrate analysis, a topic relevant for pharmaceutical testing, medical diagnostics, food adulteration analysis, and numerous other glycomics-related purposes. While carbohydrates have been extracted and commodified by humans for several millennia,1,2 and their associated chemical identity and structural motifs have been known for over a century,3,4 reliable and readily available methods for full characterization of this prevalent and naturally occurring group of molecules are lacking and under-developed. Conventional methods of analysis show promise but are constrained by several obstacles to overcome. This thesis work answers a still-relevant 2012 call by the National Research Council to invest in inventing and developing technologies that can facilitate direct detection and full characterization of carbohydrates and adds a low cost and easy-to-use package to the performance needs that were called for. Nanopore sensors, the focus of this work, have been optimized for real-time DNA sequencing to the point where scientists from any field can purchase this technology off the shelf. The technology was lacking, from the molecular-scale to the nanoscale, for nanopore carbohydrate analysis. Thus, we undertook the challenge to discover, invent and develop suitable tools and approaches. This focused on advancing and integrating three areas in particular: developing and optimizing methods for chemically customized nanopores, using high quality biological standards to test and extend our performance horizons, and adapting and applying sophisticated methods for data analysis.
Nanopores are a prominent enabling tool for single-molecule applications such as DNA sequencing, protein profiling, and glycomics, and the construction of ionic circuit elements. Silicon nitride (SiNx) is a leading scaffold for these <100 nm-diameter nanofluidic ion-conducting channels, but frequently challenging surface chemistry remains an obstacle to their use. We functionalized more than 100 SiNx nanopores with different surface terminations-acidic (Si-R-OH, Si-R-CO2H), basic (Si-R-NH2), and nonionizable (Si-R-C6H3(CF3)2)-to chemically tune the nanopore size, surface charge polarity, and subsequent chemical reactivity and to change their conductance by changes of solution pH. The initial one-reaction-step covalent chemical film formation was by hydrosilylation and could be followed by straightforward condensation and click reactions. The hydrosilylation reaction step used neat reagents with no special precautions such as guarding against water content. A key feature of the approach was to combine controlled dielectric breakdown (CDB) with hydrosilylation to create and functionalize SiNx nanopores. CDB thus replaced the detrimental but conventionally necessary surface pretreatment with hydrofluoric acid. Proof-of-principle detection of the canonical test molecule, λ-DNA, yielded signals that showed that the functionalized pores were not obstructed by chemical treatments but could translocate the biopolymer. The characteristics were tuned by the surface coating character. This robust and flexible surface coating method, freed by CDB from HF etching, portends the development of nanopores with surface chemistry tuned to match the application, extending even to the creation of biomimetic nanopores.
Solid-state nanopores (SSNs) are single-molecule resolution sensors with a growing footprint in real-time bio-polymer profiling-most prominently, but far from exclusively, DNA sequencing. SSNs accessibility has increased with the advent of controlled dielectric breakdown (CDB), but severe fundamental challenges remain: drifts in open-pore current and (irreversible) analyte sticking. These behaviors impede basic research and device development for commercial applications and can be dramatically exacerbated by the chemical complexity and physical property diversity of different analytes. We demonstrate a SSN fabrication approach attentive to nanopore surface chemistry during pore formation, and thus create nanopores in silicon nitride (SiNx) capable of sensing a wide analyte scope-nucleic acid (double-stranded DNA), protein (holo-human serum transferrin) and glycan (maltodextrin). In contrast to SiNx pores fabricated without this comprehensive approach, the pores are Ohmic in electrolyte, have extremely stable open-pore current during analyte translocation (>1 h) over a broad range of pore diameters ([Formula: see text]3- ∼30 nm) with spontaneous current correction (if current deviation occurs), and higher responsiveness (i.e. inter-event frequency) to negatively charged analytes (∼6.5 × in case of DNA). These pores were fabricated by modifying CDB with a chemical additive-sodium hypochlorite-that resulted in dramatically different nanopore surface chemistry including ∼3 orders of magnitude weaker Ka (acid dissociation constant of the surface chargeable head-groups) compared to CDB pores which is inextricably linked with significant improvements in nanopore performance with respect to CDB pores.
Intense Rayleigh waves produced by the impact of high-velocity liquid jets on brittle solids were arranged to interact with well-defined surface flaws of dimensions 50 to 200/~m. The extent of crack growth was monitored as a function of distance from the impact site. It was found that considerable crack growth as well as crack branching occurred for cracks parallel to the incident wavefront and little or no growth for orthogonal cracks. The form of the surface wave was monitored using piezoelectric crystals attached to the surface. The results are discussed in terms of recent fracture mechanics analysis of stress-wave interaction with cracks. The significance of this study to strength degradation of brittle bodies subjected to rain-drop impact is pointed out.
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