Modifying Gelators for Sensing Applications and Developing Online Resources for Organic Courses.

Part 1 of this thesis focuses on utilizing low molecular weight gels in sensing applications. Because low molecular weight gels are stimuli-responsive, they are ideal candidates for sensing. One challenge in the field is designing a gelator for a specific application, since gelators are often discovered serendipitously. In chapter 2, we review recent work understanding how structure and solvent affect gelation, which has helped streamline gelator discovery. In chapter 3, we describe an example of how one can design a gelator for sensing, specifically to detect nitrite. By modifying a known azosulfonate gelator scaffold, we synthesized five new gelators and selected the best candidate to successfully detect nitrite in dirty water. A limitation sometimes observed in gel-based sensors is poor sensitivity, especially when the analyte is not catalytic. In chapter 4, we describe our efforts to amplify the analyte signal in gel-based sensors using disassembling polymers. We describe modifying monomers of two polymer scaffolds and identified two gelators and one gelator-precursor to be used for analyte signal amplification. Part 2 of this thesis focuses on online homework in higher education with an emphasis on systems used in chemistry courses. One advantage of online homework is students receive immediate feedback, regardless of instructor time. While a number of organic chemistry homework platforms existed, we found that they did not contain the types of questions we use to assess our students learning, which are open-ended and literature-based. In chapter 5, we describe our efforts to create a feedback-driven online homework resource aligned with our course assessments. We describe a method with which undergraduate students were able to create usable questions with written feedback in an online platform. The questions were then released to incoming students as an optional resource. In chapter 6, we investigate whether our resource was effective in promoting student learning. We observed low student participation due to resource cost and student time constraints, but some evidence of improved course performance in students who used the resource. We propose future research to assess student interactions with the resource and how these affect course performance.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/120904/1/zurcherd_1.pd

Science-Literacy Integration: Equity and Learning in First-Grade, Urban Instructional Contexts

Previous research demonstrates that integration of science and literacy instruction in primary grades has positive outcomes for students’ science and literacy development. However, variations in how science and literacy are enacted suggest integration may not be sufficient to meet the literacy and science needs of all students in an equitable manner. The purpose of this study was to examine two first-grade teachers’ science integration during literacy instruction in one high- and one low-income school context within one urban district. Analysis of field notes, transcripts of lessons, and interviews revealed that expectations to integrate science during time set aside for literacy instruction without consideration of contextual factors perpetuated and concealed ongoing inequities in science education for students from the lowest income school. Further, this study adds to evidence from prior studies demonstrating that reading of science-related texts alone, as a substitute for instruction in science as a discipline, does not provide students with the resources needed to learn to think, talk, and act as scientists. Findings from this study require researchers and policy-makers to address the context-specific factors that shape instructional contexts in ways that limit or expand the potential of integrated science–literacy instruction in urban schools

Sub-micron, Metal Gate, High-к Dielectric, Implant-free, Enhancement-mode III-V MOSFETs

The performance of 300nm, 500nm and 1μm metal gate, implant free, enhancement mode III-V MOSFETs are reported. Devices are realised using a 10nm MBE grown Ga2O3/(GaxGd1-x)2O3 high-κ (κ=20) dielectric stack grown upon a δ-doped AlGaAs/InGaAs/AlGaAs/GaAs heterostructure. Enhancement mode operation is maintained across the three reported gate lengths with a reduction in threshold voltage from 0.26 V to 0.08 V as the gate dimension is reduced from 1 μm to 300 nm. An increase in transconductance is also observed with reduced gate dimension. Maximum drain current of 420 μA/μm and extrinsic transconductance of 400 µS/µm are obtained from these devices. Gate leakage current of less than 100pA and subthreshold slope of 90 mV/decade were obtained for all gate lengths. These are believed to be the highest performance submicron enhancement mode III-V MOSFETs reported to date

Integrated SSFIP-Horn Antenna at 75 GHz

We present in this paper an integrated cavity-backed patch antenna operating at 75 GHz. The design was optimized using a full-wave software based on the integral-equation method. The antenna was realized using micromachining technologies on two wafers: a silicon one supporting a membrane and a radiating patch, and a Pyrex one constituting the feeding element. The measurements are in good agreement with the theoretical predictions.Universidad Politécnica Federal de Lausann

Entropy, Dynamics and Instantaneous Normal Modes in a Random Energy Model

It is shown that the fraction f of imaginary frequency instantaneous normal modes (INM) may be defined and calculated in a random energy model(REM) of liquids. The configurational entropy S and the averaged hopping rate among the states R are also obtained and related to f, with the results R~f and S=a+b*ln(f). The proportionality between R and f is the basis of existing INM theories of diffusion, so the REM further confirms their validity. A link to S opens new avenues for introducing INM into dynamical theories. Liquid 'states' are usually defined by assigning a configuration to the minimum to which it will drain, but the REM naturally treats saddle-barriers on the same footing as minima, which may be a better mapping of the continuum of configurations to discrete states. Requirements of a detailed REM description of liquids are discussed

Enhancement Mode n-MOSFET with High-κ Dielectric on GaAs Substrate

In this paper, we report MOS heterostructures grown by molecular beam epitaxy on III-V substrates, employing a high-κ dielectric stack comprised of gallium oxide and gadolinium gallium oxide. Mobilities exceeding 12,000 and 6,000 cm2/Vs, for sheet carrier concentration ns of about 2.5x1012 cm-2 were measured on MOSFET structures on InP and GaAs substrates, respectively. These structures were designed for enhancement mode operation and include a 10 nm thick strained InGa1-xAs channel layer with In mole fraction x of 0.3 and 0.75 on GaAs and InP substrates, respectively

Mean-atom-trajectory model for the velocity autocorrelation function of monatomic liquids

We present a model for the motion of an average atom in a liquid or supercooled liquid state and apply it to calculations of the velocity autocorrelation function $Z(t)$ and diffusion coefficient $D$. The model trajectory consists of oscillations at a distribution of frequencies characteristic of the normal modes of a single potential valley, interspersed with position- and velocity-conserving transits to similar adjacent valleys. The resulting predictions for $Z(t)$ and $D$ agree remarkably well with MD simulations of Na at up to almost three times its melting temperature. Two independent processes in the model relax velocity autocorrelations: (a) dephasing due to the presence of many frequency components, which operates at all temperatures but which produces no diffusion, and (b) the transit process, which increases with increasing temperature and which produces diffusion. Because the model provides a single-atom trajectory in real space and time, including transits, it may be used to calculate all single-atom correlation functions.Comment: LaTeX, 8 figs. This is an updated version of cond-mat/0002057 and cond-mat/0002058 combined Minor changes made to coincide with published versio

A severe case of refractory esophageal stenosis induced by nivolumab and responding to tocilizumab therapy.

The prevalence of esophageal stenosis caused by immune checkpoint inhibitors in the context of induced immune mucositis and esophagitis is extremely rare. We report the case of a patient with stage IV pulmonary adenocarcinoma treated for 6 months with nivolumab who developed bilateral sterile conjunctivitis followed by oropharyngeal mucositis and esophagitis complicated by a severe esophageal stenosis. The laryngeal margin and hypopharyngeal mucosa appeared highly inflammatory with fibrinous deposits. Esophagogastroduodenoscopy revealed mucositis with a scar-like structure immediately below the upper esophageal sphincter with nonulcerative mucosa and an inflammatory aspect of the entire esophagus. No involvement of the stomach was observed. Oropharynx biopsies displayed marked lymphocytic T cell-infiltration with several foci of monocellular necrosis in the squamous epithelium. No morphologic evidence of adenocarcinoma and no signs of mycotic, bacterial or viral infection were noted. A blood sample revealed a discrete increase in the erythrocyte sedimentation rate (ESR) with no eosinophilia or leukocytosis. Liver and kidney function panel tests were normal. A thoracoabdominal CT scan reported no evidence of disease recurrence. Despite multiple boluses of methylprednisolone and high doses of prednisone continued for several months, the patient experienced very rapid symptomatological reappearance during three steroid tapering attempts and aggravation of his esophageal stenosis to an aphagic stage, requiring a nasogastric tube. This long course of high-dose corticosteroid treatment was complicated with osteoporosis-induced fractures with several spontaneous compressions of thoracolumbar vertebrae requiring an enlarged T10 to L5 cementoplasty. Anti-IL-6 blockade therapy with tocilizumab resulted in excellent clinical response, allowing the total resolution of the immune-related adverse events (irAEs) and leading to successful steroid tapering. Herein, we describe the first case of a patient who developed autoimmune mucositis and esophagitis complicated by a severe refractory esophageal stenosis induced during treatment by nivolumab, which completely resolved after personalized treatment with tocilizumab, suggesting a role of IL-6 blockade in the management of severe steroid refractory esophageal stenosis and more broadly in refractory immune-related adverse events

Phenotypic and molecular assessment of seven patients with 6p25 deletion syndrome: Relevance to ocular dysgenesis and hearing impairment

BACKGROUND: Thirty-nine patients have been described with deletions involving chromosome 6p25. However, relatively few of these deletions have had molecular characterization. Common phenotypes of 6p25 deletion syndrome patients include hydrocephalus, hearing loss, and ocular, craniofacial, skeletal, cardiac, and renal malformations. Molecular characterization of deletions can identify genes that are responsible for these phenotypes. METHODS: We report the clinical phenotype of seven patients with terminal deletions of chromosome 6p25 and compare them to previously reported patients. Molecular characterization of the deletions was performed using polymorphic marker analysis to determine the extents of the deletions in these seven 6p25 deletion syndrome patients. RESULTS: Our results, and previous data, show that ocular dysgenesis and hearing impairment are the two most highly penetrant phenotypes of the 6p25 deletion syndrome. While deletion of the forkhead box C1 gene (FOXC1) probably underlies the ocular dysgenesis, no gene in this region is known to be involved in hearing impairment. CONCLUSIONS: Ocular dysgenesis and hearing impairment are the two most common phenotypes of 6p25 deletion syndrome. We conclude that a locus for dominant hearing loss is present at 6p25 and that this locus is restricted to a region distal to D6S1617. Molecular characterization of more 6p25 deletion patients will aid in refinement of this locus and the identification of a gene involved in dominant hearing loss