Gaseous Electronics

Contains reports on two research projects.Joint Services Electronics Program (Contract DA36-039-AMC-03200(E)

Gaseous Electronics

Contains research objectives and reports on two research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 36-039-AMC-03200(E

Determining soft segment structure-property effects in the enhancement of segmented polyurethane performance

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2009.Includes bibliographical references.Liquid Crystalline Elastomer (LCE)-inspired segmented polyurethane elastomers possessing widely different extents of ordering were created to mimic the hierarchical structure of the continuous matrix and superior mechanical performance of spider silk fibers. The silk's remarkable toughness originates from a fiber morphology that possesses [beta]-pleated crystalline sheets within an amorphous matrix. In the polyurethane materials, various extents of poly(ethylene oxide) (PEO) soft segment ordering were implemented within continuous soft domains that were connected by hexamethylene diisocyanate-butanediol (HDI-BDO) hard segments. Soft segment crystallinity studies revealed the need to optimize the extent of continuous soft domain ordering. Highly crystalline PEO soft segments, while they display good microphase segregation properties, sacrifice extensibility due to their high melting transition temperature. Moderately crystalline PEO soft segments, meanwhile, possess less defined phase segregation but enhanced mechanical properties from their reversible dispersed crystalline soft segment domains. Non-crystalline Pluronic copolymer systems had good mechanical properties that resulted from both a strong hard segment incompatibility and a highly mobile soft segment matrix. Hydrogen-bonded hard domain shearing during in-situ tensile deformation yields oriented hard blocks that align at a preferred tilt angle of ±60° from the strain direction. Extensive alignment and orientation of the moderately-ordered PEO soft segments occurred during deformation, which was consistent with its observed mechanical behavior. Pluronic-containing segmented polyurethanes formed an ordered mesophase in the continuous soft matrix during deformation. A series of cyclic, aliphatic polyurethanes with dicyclohexyl methane diisocyanate (HMDI) hard segments and poly(tetramethylene oxide) (PTMO) soft segments was synthesized to study compositional effects on the extent of soft segment mixing, and how these effects translated to both mechanical and barrier performance. Shorter soft segment chain systems displayed a greater hard segment compatibility, which resulted in materials that were both more rigid mechanically and provided better barrier characteristics.(cont.) Longer soft segments in the continuous polymer matrix displayed a more phase segregated structure, which enhanced their mechanical properties but sacrificed barrier effectiveness. Incorporation of dimethyl propane diol (DMPD), a branched chain extender, created a completely amorphous polyurethane matrix. Polyurethane/Laponite nanocomposites were also created using particles that were capable of preferentially associating with hard or soft segments. HMDI-BDO-PTMO polyurethane/Laponite nanocomposites demonstrated drastically reduced mechanical performance (~13-fold decrease in toughness and ~10-fold decrease in extensibility). The deteriorated mechanical performance was attributed to the formation of an interconnected hard segment continuous morphology that significantly reduced matrix extensibility. HMDI-DMPDPTMO polyurethane/Laponite composites, on the other hand, only experienced modest reductions in extensibility (-70% of total initial extensibility) while maintaining toughess and increasing initial modulus 10-fold. Mechanical behavior resulted from well-dispersed Laponite clay platelets that reinforced the amorphous polymer matrix while imposing modest chain segmental mobility restrictions.by Ryan Scott Waletzko.Ph.D

Health insurance is associated with decreased odds for undiagnosed prediabetes and type 2 diabetes in American adults

Over a third of adults in the United States have prediabetes, and many of those with prediabetes will progress to type 2 diabetes within 3–5 years. Health insurance status may factor into a proper diagnosis of prediabetes and diabetes. This study sought to determine the associations between health insurance and undiagnosed prediabetes and diabetes in a national sample of American adults. Publicly available data from 13,029 adults aged 18–64 years from the 2005–2016 waves of the National Health and Nutrition Examination Survey were analyzed. Health insurance type (Medicaid, Private, Other, None) was self-reported. Prediabetes and diabetes status were assessed with measures of self-report, glycohemoglobin, fasting plasma glucose, and two-hour glucose. Covariate-adjusted logistic models were used for the analyses. Overall, 5976 (45.8%) participants had undiagnosed prediabetes, while 897 (6.8%) had undiagnosed diabetes. Having health insurance was associated with decreased odds ratios for undiagnosed prediabetes: 0.87 (95% confidence interval (CI: 0.79, 0.95)) for private insurance, 0.84 (CI: 0.73, 0.95) for other insurance, and 0.78 (CI: 0.67, 0.90) for Medicaid. Moreover, having private health insurance was associated with 0.82 (CI: 0.67, 0.99) decreased odds for undiagnosed diabetes. Health insurance coverage and screening opportunities for uninsured individuals may reduce prediabetes and diabetes misclassifications

Combining Biocompatible and Biodegradable Scaffolds and Cold Atmospheric Plasma for Chronic Wound Regeneration

Skin regeneration is a quite complex process. Epidermal differentiation alone takes about 30 days and is highly regulated. Wounds, especially chronic wounds, affect 2% to 3% of the elderly population and comprise a heterogeneous group of diseases. The prevailing reasons to develop skin wounds include venous and/or arterial circulatory disorders, diabetes, or constant pressure to the skin (decubitus). The hallmarks of modern wound treatment include debridement of dead tissue, disinfection, wound dressings that keep the wound moist but still allow air exchange, and compression bandages. Despite all these efforts there is still a huge treatment resistance and wounds will not heal. This calls for new and more efficient treatment options in combination with novel biocompatible skin scaffolds. Cold atmospheric pressure plasma (CAP) is such an innovative addition to the treatment armamentarium. In one CAP application, antimicrobial effects, wound acidification, enhanced microcirculations and cell stimulation can be achieved. It is evident that CAP treatment, in combination with novel bioengineered, biocompatible and biodegradable electrospun scaffolds, has the potential of fostering wound healing by promoting remodeling and epithelialization along such temporarily applied skin replacement scaffolds

Computational design of accelerated life testing applied to frozen green beans

Three different accelerated life tests (ALT) were designed by computer simulation to investigate their practical applicability to quantify kinetics of quality loss in frozen stored foods. Heat transfer and quality degradation inside a green bean were simulated, using a spectral finite element method (SFEM), to develop pseudo-experimental data. Temperature fluctuations inside a refrigerator were simulated, by a piecewise linear stochastic differential equation, and integrated into the SFEM program. Thereafter, the simulated data was treated by non-linear regression analysis to estimate the kinetic parameters. The different ALT tests were then compared in terms of precision and accuracy. This study shows that temperature fluctuations, inside a refrigerator, influence the accuracy of the kinetic estimates, and if the temperature spectrum is used to derive kinetic estimates, it is possible to apply accurately ALT methodologies to frozen foods

Computational shelf-life dating : complex systems approaches to food quality and safety

Shelf-life is defined as the time that a product is acceptable and meets the consumers expectations regarding food quality. It is the result of the conjunction of all services in production, distribution, and consumption. Shelf-life dating is one of the most difficult tasks in food engineering. Market pressure has lead to the implementation of shelf-life by sensory analyses, which may not reflect the full quality spectra. Moreover, traditional methods for shelf-life dating and small-scale distribution chain tests cannot reproduce in a laboratory the real conditions of storage, distribution, and consumption on food quality. Today, food engineers are facing the challenges to monitor, diagnose, and control the quality and safety of food products. The advent of nanotechnology, multivariate sensors, information systems, and complex systems will revolutionize the way we manage, distribute, and consume foods. The informed consumer demands foods, under the legal standards, at low cost, high standards of nutritional, sensory, and health benefits. To accommodate the new paradigms, we herein present a critical review of shelf-life dating approaches with special emphasis in computational systems and future trends on complex systems methodologies applied to the prediction of food quality and safety.Fundo Europeu de Desenvolvimento Regional (FEDER) - Programa POS-ConhecimentoFundação para a Ciência e a Tecnologia (FCT) - SFRH/BPD/26133/2005, SFRH/ BPD/20735/200

Using Performance Assessments to Increase Motivation in the Foreign Language Classroom at the High School Level

This work describes the importance of Integrated Performance Assessments in the foreign language field can promote changes in the learning and teaching of a foreign language. But new practices can be slow to implement due to lack of distribution of knowledge, time and budget constraints, and teachers’ attitudes and practices in the classroom. The national foreign language standards were created as a guideline for schools as to the knowledge students should acquire. Integrated Performance Assessments (IPA) were developed to connect this goal to the classroom as a process to evaluate students’ learning. There is a need to clarify the use of IPA compared to traditional end of chapter tests and to what extent these tests serve to promote the standards. The researcher compared two approaches for assessing foreign language learning through comparison of the students’ grades from IPA to the end of chapter test grades from a convenience sample of students using grades recorded in a teacher’s grade book. There was wide deviation in traditional end of chapter scores which could indicate a problem in evaluating students’ knowledge using this more traditional scoring method. The students as a whole received better grades on the IPA as there was a narrow deviation which appeared to show that students had more success in their learning according to the IPA. Use of IPA may have more correctly reflected students’ foreign language learning and proficiency

Social Loafing and Team-Based Learning: Assessing Whether Team-Based Learning

Plan ASocial loafing in group projects is a problem that affects the group’s productivity and the team’s experience (Gagne et al.,1999; Pfaff & Huddleston, 2003; Teng & Luo, 2015). A potential remedy to this problem is a research-based teaching style called Team-Based Learning (TBL; Sibley et al., 2014; Team Based Learning Collaborative, 2020). In general, it is hypothesized that TBL practices will lead to less perceived social loafing. A survey asking about a past college group project was put up on UW-Stout Sona, where 113 students completed the survey. This survey consisted of two existing measures (i.e., Perceived Social Loafing Questionnaire [PSLQ] and Social Loafing Tendency Questionnaire [SLTQ]) as well as additional questions created based off the literature on social loafing and TBL. Data was analyzed using an independent samples t-test, correlations, and one-way ANOVAs. Results showed that two hypotheses were supported: students who report the course as being important or very important will self-report less individual social loafing and students who report feeling more socially connected to their groups will self-report less individual social loafing. The other 5 hypotheses were not supported. The present study seeks to add to the current social loafing literature as well as the TBL literature by addressing the research gap that exists. Also, to gain a better understanding of how the TBL teaching method could potentially reduce the amount of social loafing in the classroom. The hope is that instructors who utilize groupwork can use this research to inform their teaching practices

AT-HOME SYSTEMS AND CONTROLS LABORATORY

At-home laboratories are inexpensive hardware kits that students take home and work on much like a problem set. The kits have an embedded microcontroller and communicate to the student’s home PC over a serial port. The home PC provides the needed computational horsepower for experiment control, data collection, data analysis and reporting. The microcontroller handles real-time control tasks. Two first-generation kits were developed, a fourth-order, linear mass-spring-damper system for frequency response and system identification, and an analog filtering system that uses music and synthetic sound as an input for understanding the properties of analog filters. Twenty five kits were constructed and used by students. Based on this pilot, improved, second generation kits have been designed