Experimental, Theoretical, and Device Application Development of Nanoscale Focused Electron-Beam-Induced Deposition

To elucidate the effects of beam heating in electron beam-induced deposition (EBID), a Monte-Carlo electron-solid interaction model has been employed to calculate the energy deposition profiles in bulk and nanostructured SiO2. Using these profiles, a finite element model was used to predict the nanostructure tip temperatures for standard experimental EBID conditions. Depending on the beam energy, beam current, and nanostructure geometry, the heat generated can be substantial. This heat source can subsequently limit the EBID growth by thermally reducing the mean stay time of the precursor gas. Temperature dependent EBID growth experiments qualitatively verified the results of the electron beam-heating model. Additionally, experimental trends for the growth rate as a function of deposition time supported the conclusion that electron beam-induced heating can play a major role in limiting the EBID growth rate of SiO2 nanostructures. In an EBID application development, two approaches to maskless, direct-write lithography using electron beam-induced deposition (EBID) to produce ultra-thin masking layers were investigated. A single layer process used directly written SiOx features deposited from a tetraethoxysilane (TEOS) precursor vapor as a masking layer for amorphous silicon thin films. A bilayer process implemented a secondary masking layer consisting of standard photoresist into which a pattern—directly written by EBID tungsten from WF6 precursor—was transferred. The single layer process was found to be extremely sensitive to the etch selectivity of the plasma etch. As a result, patterns were successfully transferred into silicon, but only to a minimal depth. In the bilayer process, EBID tungsten was written onto photoresist and the pattern transferred by means of an oxygen plasma dry development. A brief refractory descum plasma etch was implemented to remove the peripheral tungsten contamination prior to the development process. Conditions were developed to reduce the spatial spread of electrons in the photoresist layer and obtain minimal linewidths, which enabled patterning of ~ 35 nm lines. Additionally, an EBID-based technique for field emitter repair was applied to the Digital Electrostatically focused e-beam Array Lithography (DEAL) parallel electron beam lithography configuration. Damaged or missing carbon nanofiber (CNF) emitters are very common in these prototype devices, so there is a need for a deterministic repair process. Relatively carbon-free, high aspect ratio tungsten nanofibers were deposited from a WF6 precursor in a gated cathode and a damaged triode (DEAL) device. The I-V response of the devices during vacuum FE testing indicated stable, cold field emission from the EBID cathodes. The field emission threshold voltage was shown to decrease from -130 V to -90 V after a short initiation period. Finally, lithography was performed using the repaired device to write a series of lines in PMMA with variable focus voltage. Successful focusing of the beam with increased focus voltage was evident in the patterned and developed PMMA. The I-V and lithography results were comparable to CNF-based DEAL devices indicating a successful repair technique

The Bellingham Golf and Country Club Since 1912

In the beginning there was golf. Golf is the oldest and noblest of all sports. No golfer would dispute this assertion. According to Michael Murphy, there is an old Scottish saying which states, The game was invented a billion years ago-- don\u27t you remember? . If you don\u27t remember, the reason may be that no one bothered to record the process for you. This is one of the reasons for the creation of this short history of the Bellingham Golf and Country Club

Every Interchange has a story

The I-69 Ohio River Crossing Project includes four major interchanges, three new interchanges, and one reconstructed interchange. This session will discuss the design evolution of each interchange from conceptual design through NEPA to the design build process. We will also discuss building the first 6 roundabouts in a region and navigating the value engineering and IAD processes, properties, railroads, and transmission lines

BioGauges: Toward More Objective Evaluation of Biometrically-Based Interfaces

In an effort to better understand and fully characterize human interaction with biometrically-based interfaces, the BioGauges method and toolset are presented. BioGauges provide a mechanism for determining the range, reliability, and granularity of control possible for a user operating a biometrically-based interface. We first demonstrate the method with a study of ten able-bodied people characterizing two different continuous biometrically-based interfaces with a thresholded task. Then, we further demonstrate the method by assessing the spatial granularity of two continuous biometrically-based interfaces for five people with varying stages of paralysis due to amyotrophic lateral sclerosis (ALS)

A Novel Norspermidine Responsive Signaling Pathway in Vibrio Cholerae Affecting Biofilm Formation

Polyamines are a class of simple molecules that are nearly ubiquitous to life. As signals they are involved in cell signaling and cellular processes. In the aquatic pathogen Vibrio cholerae it has been shown that the polyamine norspermidine dramatically affects biofilm formation. Addition of norspermidine to cultures of V. cholerae will cause up to a threefold increase in biofilm formation compared to untreated cells. Two proteins are implicated in the cells response to norspermidine. The periplasmic protein NspS and the integral inner-membrane protein MbaA. The protein NspS is similar to periplasmic transport proteins involved in the transport of polyamines and MbaA is similar to proteins involved in degrading the second messenger c-di-GMP. The second messenger c-di-GMP at low intracellular concentrations leads to less biofilm formation and higher levels lead to increased biofilm formation. It was hypothesized that NspS senses norspermidine and in turn affects the activity of MbaA which could affect biofilm formation. NspS was first analyzed for the ability to bind norspermidine via a thermal shift assay. When a pure sample of NspS was exposed to norspermidine there was a dramatic shift in thermal stability over NspS without norspermidine. The increase in thermal stability indicates binding. Further, MbaA was shown directly to be capable of degrading molecules of c-di-GMP confirming it acts as a phosphodiesterase. The data generated in this study provides evidence for a new signaling system in which norspermidine regulates biofilm formation

Computer-Based Instruction and Cognitive Load

Following cognitive load theory, we used a computer-based software training paradigm to determining the optimal number of steps or information chunks to present before practice opportunities. Results demonstrating that the size of information chunks presented and the type of practice used individually influenced participants\u27 ability to effectively learn via computer-based instruction. These findings contribute to the literature by showing the importance of practice and optimal segment sizes for learning via a computer

Bayesian comparison of cost-effectiveness of different clinical approaches to diagnose coronary artery disease

The objective of this study was to compare the cost-effectiveness of four clinical policies (policies I to IV) in the diagnosis of the presence or absence of coronary artery disease. A model based on Bayes' theorem and published clinical data was constructed to make these comparisons. Effectiveness was denned as either the number of patients with coronary disease diagnosed or as the number of quality-adjusted life years extended by therapy after the diagnosis of coronary disease.The following conclusions arise strictly from analysis of the model and may not necessarily be applicable to all situations. 1) As prevalence of coronary disease in the population increased, it caused a linear increase in cost per patient tested, but a hyperbolic decrease in cost per effect, that is, increased cost-effectiveness. Thus, cost-effectiveness of all policies (I to IV) was poor in populations with a prevalence of disease below 10%, for example, asymptomatic people with no risk factors. 2) Analysis of the model also indicates that at prevalences less than 80%, exercise thallium scintigraphy alone as a first test (policy II) is a more cost-effective initial test than is exercise electrocardiography alone as a first test (policy I) or exercise electrocardiography first combined with thallium imaging as a second test (policy IV). 3) Exercise electrocardiography before thallium imaging (policy IV) is more cost-effective than exercise electrocardiography alone (policy I) at prevalences less than 80%. 4) Noninvasive exercise testing before angiography (policies I, II and IV) is more cost-effective than using coronary angiography as the first and only test (policy III) at prevalences less than 80%. 5) Above a threshold value of prevalence of 80% (for example patients with typical angina), proceeding to angiography as the first test (policy III) was more cost-effective than initial noninvasive exercise tests (policies I, II and IV).One advantage of this quantitative model is that it estimates a threshold value of prevalence (80%) at which the rank order of policies changes. The model also allows substitution of different values for any variable as a way of accounting for the uncertainty inherent in the data. In conclusion, it is essential to consider the prevalence of disease when selecting the most cost-effective clinical approach to making a diagnosis

Botulinum Toxin for giant omphalocele abdominal wall reconstruction

Introduction The use of Botulinum Toxin A (BTA) has been shown to be safe and efficacious in neuromuscular blockade in both adult and pediatric patients. While BTA injections have been used safely in the pediatric population for a variety of medical conditions, its use in pediatric abdominal wall reconstruction has not been described. This report describes a unique surgical technique that will increase abdominal domain and allow for earlier closure of giant omphalocele defects. Case report A 33-week twin premie was born with a giant omphalocele. In an effort to achieve primary closure without the need for mesh, BTA injections were performed under ultrasound guidance two weeks prior to a planned closure. BTA injections included administration of 8 units at separate sites of the abdominal musculature bilaterally. After reduction, a component separation, and primary approximation of the fascial defect were achieved without signs of abdominal compartment syndrome. Conclusion BTA injection into the abdominal wall musculature provides a safe and effective mechanism to increase laxity of the abdominal wall musculature and decrease tension on the reconstruction for giant omphaloceles defects. The use of BTA may allow earlier repair in this subset of patients without the need for mesh