Controlled Growth, Patterning and Placement of Carbon Nanotube Thin Films

Controlled growth, patterning and placement of carbon nanotube (CNT) thin films for electronic applications are demonstrated. The density of CNT films is controlled by optimizing the feed gas composition as well as the concentration of growth catalyst in a chemical vapor deposition process. Densities of CNTs ranging from 0.02 CNTs/{\mu}m^2 to 1.29 CNTs/{\mu}m^2 are obtained. The resulting pristine CNT thin films are then successfully patterned using either pre-growth or post-growth techniques. By developing a layered photoresist process that is compatible with ferric nitrate catalyst, significant improvements over popular pre-growth patterning methods are obtained. Limitations of traditional post-growth patterning methods are circumvented by selective transfer printing of CNTs with either thermoplastic or metallic stamps. Resulting as-grown patterns of CNT thin films have edge roughness (< 1 {\mu}m) and resolution (< 5 {\mu}m) comparable to standard photolithography. Bottom gate CNT thin film devices are fabricated with field-effect mobilities up to 20 cm^2/Vs and on/off ratios of the order of 10^3. The patterning and transfer printing methods discussed here have a potential to be generalized to include other nanomaterials in new device configurations

Accounting Quality, Corporate Acquisition, and Financing Decisions

This paper examines the extent to which the quality of financial accounting information disciplines manager interests to align with stockholder interests in corporate acquisition and financing decisions. I find that, after controlling for financing constraints, recent performance and payout policy, the tendency of firm managers to time the market is significantly constrained for firms with high-quality financial accounting information. Further, I find that the disciplining impact of accounting information is mostly driven by firms that bid for acquisitions financed with stock issuance. I also provide corroborating evidence by examining a similar disciplining role of financial accounting information in the seasoned public offering markets. I find no such effect for potential acquisitions financed through cash. The evidence suggests that high-quality accounting information allows stockholders to discipline firm managers that are motivated to take advantage of the misvaluation. Further, the results suggest the effectiveness of accounting information as a control mechanism is pronounced for firms that pursue more value-decreasing investment projects.Doctor of Philosoph

Controllable synthesis of molybdenum tungsten disulfide alloy for vertically composition-controlled multilayer

The effective synthesis of two-dimensional transition metal dichalcogenides alloy is essential for successful application in electronic and optical devices based on a tunable band gap. Here we show a synthesis process for Mo&lt;inf&gt;1-x&lt;/inf&gt;W&lt;inf&gt;x&lt;/inf&gt;S&lt;inf&gt;2&lt;/inf&gt; alloy using sulfurization of super-cycle atomic layer deposition Mo&lt;inf&gt;1-x&lt;/inf&gt;W&lt;inf&gt;x&lt;/inf&gt;O&lt;inf&gt;y&lt;/inf&gt;. Various spectroscopic and microscopic results indicate that the synthesized Mo&lt;inf&gt;1-x&lt;/inf&gt;W&lt;inf&gt;x&lt;/inf&gt;S&lt;inf&gt;2&lt;/inf&gt; alloys have complete mixing of Mo and Watoms and tunable band gap by systematically controlled composition and layer number. Based on this, we synthesize a vertically composition-controlled (VCC) Mo&lt;inf&gt;1-x&lt;/inf&gt;W&lt;inf&gt;x&lt;/inf&gt;S&lt;inf&gt;2&lt;/inf&gt; multilayer using five continuous super-cycles with different cycle ratios for each super-cycle. Angle-resolved X-ray photoemission spectroscopy, Raman and ultraviolet-visible spectrophotometer results reveal that a VCC Mo&lt;inf&gt;1-x&lt;/inf&gt;W&lt;inf&gt;x&lt;/inf&gt;S&lt;inf&gt;2&lt;/inf&gt; multilayer has different vertical composition and broadband light absorption with strong interlayer coupling within a VCC Mo&lt;inf&gt;1-x&lt;/inf&gt;W&lt;inf&gt;x&lt;/inf&gt;S&lt;inf&gt;2&lt;/inf&gt; multilayer. Further, we demonstrate that a VCC Mo&lt;inf&gt;1-x&lt;/inf&gt;W&lt;inf&gt;x&lt;/inf&gt;S&lt;inf&gt;2&lt;/inf&gt; multilayer photodetector generates three to four times greater photocurrent than MoS&lt;inf&gt;2&lt;/inf&gt;-and WS&lt;inf&gt;2&lt;/inf&gt;-based devices, owing to the broadband light absorption. &amp;#169; 2015 Macmillan Publishers Limitedopen1

Cycloadditions in mixed aqueous solvents: the role of the water concentration

We examined the kinetics of a series of cycloaddition reactions in mixtures of water with methanol, acetonitrile and poly(ethylene glycol) (MW 1000). The reactions include the Diels–Alder (DA) reaction between cyclopentadiene and N-n-butylmaleimide or acridizinium bromide, the retro-Diels-Alder (RDA) reaction of 1,4,4a,9a-tetrahydro-4a-methyl-(1α,4α,4aα,9aα)-1,4-methaneanthracene-9,10-dione and the 1,3-dipolar cycloaddition of benzonitrile oxide with N-n-butylmaleimide. Plots of logk vs the molar concentration or volume fraction of water are approximately linear, but with a characteristic break around 40 M water. This break, absent for the RDA reaction, is ascribed to hydrophobic effects. Comparison with aqueous mixtures of the more hydrophobic 1-propanol shows that these mixtures induce qualitatively similar effects on the rate, but that preferential solvation effects cause the mixtures of 1-propanol to exhibit a more complex behavior of logk on composition. The results are analyzed using the Abraham–Kamlett–Taft model. The solvent effects in aqueous mixtures are not satisfactorily described by this model. For some cycloadditions, small maxima in rate are observed in highly aqueous mixtures of alcohols. The origin of these maxima and the aforementioned breaks is most likely the same.

Fecal microbiota transplant rescues mice from human pathogen mediated sepsis by restoring systemic immunity.

Death due to sepsis remains a persistent threat to critically ill patients confined to the intensive care unit and is characterized by colonization with multi-drug-resistant healthcare-associated pathogens. Here we report that sepsis in mice caused by a defined four-member pathogen community isolated from a patient with lethal sepsis is associated with the systemic suppression of key elements of the host transcriptome required for pathogen clearance and decreased butyrate expression. More specifically, these pathogens directly suppress interferon regulatory factor 3. Fecal microbiota transplant (FMT) reverses the course of otherwise lethal sepsis by enhancing pathogen clearance via the restoration of host immunity in an interferon regulatory factor 3-dependent manner. This protective effect is linked to the expansion of butyrate-producing Bacteroidetes. Taken together these results suggest that fecal microbiota transplantation may be a treatment option in sepsis associated with immunosuppression