No description available.

Because of a demonstrable need, there should be a course for the study of Appalachian art in the high school curriculum. This study is a proposal for the study of traditional Appalachian art and its importance to the promotion and preservation of the arts and crafts in the Appalachian region. This course consists of background information on selected traditional Appalachian art, contact and interaction with local artists and craftspeople, and student hands-on experience in the art forms considered. Detailed unit and lesson plans are included in the following areas: Spinning and Weaving, Dyeing, Basketry, Quilting, Pottery, Woodcarving, Blacksmithing, Vernacular Architecture, and Handmade Instruments of Country Music. This course has been taught by the writer at Science Hill High School in Johnson City, Tennessee, and was enthusiastically received by both students and members of the community.

This thesis examines two important problems in fluid dynamics: that of a partially immersed sphere spinning in a bath of liquid and the measurement of flow velocities around a free flying butterfly. Although the actual problems are quite different, each problem incorporates many of the same principles and techniques. When a hard-boiled egg spins through a pool of milk on the kitchen counter, the milk rises up the sides of the egg and droplets are ejected. This phenomenon occurs when any partially submerged object whose radius increases upward from the fluid surface (e.g., spheres, inverted cones, rings, etc.), spins in a shallow bath of fluid. The fluid ejects from the surface at the maximum diameter in one of three ejection modes: jets, sheets, or sheet breakup. Additionally, a surprisingly large flow rate is induced by the spinning object. Spheres are used in this study to determine the effects of experimental parameters on the induced flow rate. High-speed imaging is used to experimentally characterize the modes of ejection and measure sheet breakup distance and velocities of liquid within liquid sheets. A theoretical model is derived using an integral momentum boundary layer analysis both beneath the free surface and in the thin film attached to the sphere. Experimental results are presented in comparison with predicted behavior with good agreement. The suitability of using a spinning sphere as a pump is also discussed. Second, the use of PIV to measure flow velocities around living species is becoming more widely adopted. Current efforts are starting to measure 3D, time-resolved velocities around insects in tethered flight. This work investigates the use of Synthetic Aperture PIV (SAPIV) in obtaining 3D, time-resolved volumetric velocity fields around a painted lady butterfly in free flight. Results are presented from several time steps during both the down stroke and upstroke of the butterfly showing the development of the leading edge vortex. The velocity field results have limited spatial resolution; however, the results show that SAPIV has potential in further investigating these flow structures. The reconstructed visual hull of the butterfly is also discussed.

No description available.

Age and sex are risk factors of Alzheimer's disease (AD). Among the neurotransmitter systems, gamma-aminobutyric acid (GABA) has been implicated in AD pathogenesis but the relevance of sex-specific GABAergic dysfunction during AD progression remains unknown. In the present study, we utilized state-of-the-art high-resolution magic angle spinning nuclear magnetic resonance to systematically monitor the brain region-, age-, and sex-specific modulation of GABA levels in wild-type and Tg2576 mice with amyloid pathology. In addition, we followed the possible role of reactive astrocytes in sex-specific GABA modulation. In female Tg2576 mice, hippocampal GABA levels were significantly elevated, along with higher number of reactive astrocytes and amyloid deposition. The elevated GABA was found to be produced via the monoamine oxidase-B route from putrescine in reactive astrocytes, more substantially in female than male mice, thus suggesting a role of astrocytes in memory impairment and sex-related differences in AD. Our results paint a coherent model of memory impairment in AD and signify that dynamic changes in regional GABA may be at the root of marked sex disparities observed in AD.

Tesis por compendio / [ES] La pérdida y el desperdicio de alimentos supone un problema global de gran magnitud con implicaciones significativas en los ámbitos ambiental, económico y social. Una fracción importante de dichas pérdidas está producida por las enfermedades postcosecha causadas por fitopatógenos. Meyerozyma caribbica encapsulada en recubrimientos comestibles ha demostrado ser efectiva como control biológico en frutos. Sin embargo, las técnicas convencionales de producción de recubrimientos no garantizan la homogeneidad del tratamiento sobre el alimento, pudiendo afectar a su efectividad. En este sentido, las nanofibras hiladas mediante procesos electro y aerohidrodinámicos pueden actuar como una matriz biopolimérica para atrapar dichos microorganismos, y pueden ser depositadas homogéneamente en la superficie de los alimentos, y esto, junto a que son estructuras con una gran superficie-volumen, las hace más activas y eficientes. La etapa 1, consistió en la optimización y la caracterización fisicoquímica de las disoluciones poliméricas (goma de anacardo, CG; FucoPol, FP; poli óxido de etileno, PEO; pululano, Pul). La etapa 2, consistió en la obtención de estructuras mediante electrospray y electrospinning, éstas se caracterizaron mediante SEM, ATR-FTIR, WAXS, TGA y DSC. La etapa 3 consistió en la encapsulación de M. caribbica en nanofibras de pululano, CG:PEO y FP:PEO mediante electrospinning. Las nanofibras se caracterizaron mediante SEM, ATR-FTIR y TGA. Se determinó la viabilidad de M. caribbica y se evaluó la actividad antifúngica de las nanofibras frente a 6 hongos de interés comercial. La etapa 4, consistió en el análisis in vivo de frutos cubiertos con nanofibras adicionadas con M. caribbica aplicadas por Solution Blow Spinning (SBS) para ello se determinó la viabilidad de M. caribbica en las nanofibras y se evaluó la actividad antifúngica in vitro e in vivo como tratamientos preventivos y curativos frente a C. gloeosporioides. Finalmente, se evaluó el efecto de las nanofibras sobre los parámetros de calidad de los aguacates. Las microestructuras obtenidas con CG, mostraron cápsulas esféricas sin depresiones irregulares que encapsularon al compuesto modelo (ß-caroteno). Las cápsulas de CG brindaron protección térmica y fotoestabilidad al ß-caroteno. Por otro lado, FP, FP:Pul y FP:PEO mostraron fibras helicoidales cilíndricas, lisas y gruesas. Mediante WAXS, en las nanofibras de FP:Pul y FP:PEO se detectaron nuevos picos a ángulos por debajo de los 10º, lo que sugiere que FucoPol podría afectar la estructura polimérica de otros materiales con una estructura secundaria helicoidal. Las nanofibras de pululano, CG:PEO y FP:PEO con M. caribbica mostraron nanofibras cilíndricas, lisas y homogéneas. Los polímeros utilizados brindaron protección térmica a la levadura. Las nanofibras de pululano mostraron la viabilidad más alta de M. caribbica y el mayor porcentaje de inhibición del crecimiento de los 6 hongos evaluados. Mediante SBS se obtuvieron fibras homogéneas, continuas y rizadas. SBS garantizó una alta viabilidad de M. caribbica en las nanofibras aplicadas en la superficie de los aguacates bajo diferentes condiciones evaluadas. Las nanofibras de pululano con M. caribbica como tratamiento preventivo inhibieron por completo el crecimiento de C. gloeosporioides. Además, la aplicación de las nanofibras sobre los aguacates no afectó los parámetros de calidad. El pululano, la CG y el FP en combinación con PEO y pululano se han estudiado por primera vez para formar estructuras mediante procesos electrohidrodinámicos y aerohidrodinámicos. Estos resultados obtenidos, sugieren un alto potencial de las nanofibras para su uso en la industria alimentaria y representan una alternativa interesante para el tratamiento post-cosecha de frutos en el control de enfermedades fúngicas, contribuyendo de esta manera a reducir la pérdida en la producción de alimentos. / [CA] La pèrdua i el malbaratament d'aliments representen un gran problema mundial amb implicacions significatives en els àmbits ambiental, econòmic i social. Una part considerable d'estes pèrdues es deu a malalties post collita causades per fitopatògens. Meyerozyma caribbica, encapsulada en recobriments comestibles, ha demostrat ser efectiva com a control biològic en fruites. No obstant això, els mètodes tradicionals de producció de recobriments sovint no asseguren un tractament uniforme a la superfície dels aliments, cosa que pot comprometre l'eficàcia. En este context, les nanofibres filades mitjançant processos electro- i aerohidrodinàmics poden servir com a matriu bio polimèrica per atrapar estos microorganismes, garantint la deposició homogènia sobre les superfícies dels aliments. El seu gran ràtio superfície-volum enfortix l'activitat i l'eficiència. L'etapa 1 va implicar l'optimització i la caracterització fisicoquímica de les solucions de polímers (goma d'anacard, CG; FucoPol, FP; i poli òxid d'etilè, PEO); pululan, Pul). L'etapa 2 es va centrar en la fabricació d'estructures mitjançant electrospray i electrospinning, caracteritzades per SEM, ATR-FTIR, WAXS, TGA i DSC. L'etapa 3 va incloure l'encapsulació de M. caribbica en nanofibres de pullulan, CG:PEO i FP:PEO per electrofilat. Les nanofibres van ser caracteritzades per SEM, ATR-FTIR i TGA. La viabilitat de M. caribbica es va determinar i l'activitat antifúngica de les nanofibres es va avaluar contra 6 fongs d'interés comercial. L'etapa 4 va consistir en l'anàlisi in vivo de fruites recobertes amb nanofibres afegides amb M. caribbica aplicades per mitjà de Solution Blow Spinning (SBS); per això, es va determinar la viabilitat de M. caribbica a les nanofibres i es va avaluar l'activitat antifúngica in vitro i in vivo com a tractaments preventius i curatius enfront de C. gloeosporioides. Finalment, es va avaluar l'efecte de les nanofibres en els paràmetres de qualitat dels alvocats. Les microestructures obtingudes amb CG van mostrar càpsules esfèriques sense depressions irregulars que encapsulaven el compost model (ß-caroté). Les càpsules de CG van proporcionar protecció tèrmica i foto estabilitat al ß-caroté. D'altra banda, FP, FP:Pul i FP:PEO van mostrar fibres cilíndriques, suaus i gruixudes. Mitjançant WAXS es van detectar nous pics a angles per davall dels 10°, la qual cosa suggerix que FucoPol podria afectar l'estructura d'altres materials amb una estructura secundària helicoidal. Les nanofibres de pululan, CG:PEO i FP:PEO amb M. caribbica van mostrar nanofibres cilíndriques, suaus i homogènies. Els polímers utilitzats van proporcionar protecció tèrmica al llevat. Les nanofibres de pululan van mostrar la màxima viabilitat de M. caribbica i el màxim percentatge d'inhibició del creixement dels 6 fongs provats. Utilitzant SBS, es van obtindre fibres homogènies, contínues i arrissades. SBS va garantir una alta viabilitat de M. caribbica a les nanofibres aplicades a la superfície dels alvocats en diferents condicions avaluades. Les nanofibres de pululan amb M. caribbica com a tractament preventiu van inhibir completament el creixement de C. gloeosporioides. A més, l'aplicació de nanofibres en alvocats no va afectar els paràmetres de qualitat. El Pululan, la CG i l'FP en combinació amb PEO i pululan han estat estudiades per primera vegada per a formar estructures mitjançant processos electro hidrodinàmics i aero hidrodinàmics. Estos resultats obtinguts suggerixen un alt potencial de les nanofibres per a ser utilitzades en la indústria alimentària i representen una interessant alternativa per al tractament post collita de les fruites en el control de les malalties fúngiques, contribuint a reduir la pèrdua en la producció d'aliments. / [EN] Food loss and waste represent a significant global challenge with substantial implications across environmental, economic, and social domains. A considerable portion of these losses stems from postharvest diseases caused by phytopathogens. Meyerozyma caribbica, encapsulated in edible coatings, has demonstrated effectiveness as a biological control agent in fruits. However, conventional coating production methods often fail to ensure uniform treatment on food surfaces, potentially compromising efficacy. In this context, nanofibers spun through electro- and aerohydrodynamic processes can serve as a biopolymeric matrix to entrap such microorganisms, ensuring homogeneous deposition on food surfaces. Their large surface-area-to-volume ratio enhances activity and efficiency. Stage 1 involved optimizing and characterizing polymer solutions (cashew gum, CG; FucoPol, FP; polyethylene oxide, PEO; pullulan, Pul). Stage 2 focused on fabricating structures via electrospray and electrospinning, characterized by SEM, ATR-FTIR, WAXS, TGA, and DSC. Stage 3 entailed encapsulating M. caribbica in pullulan, CG:PEO, and FP:PEO nanofibers via electrospinning, fibers were characterized by SEM, ATR-FTIR, and TGA. M. caribbica viability and the nanofibers' antifungal activity were assessed against six commercially relevant fungi. Stage 4 comprised in vivo analysis of fruits coated with nanofibers containing M. caribbica applied via Solution Blow Spinning (SBS). Viability of M. caribbica in the nanofibers and their antifungal efficacy were determined in vitro and in vivo as preventive and curative treatments against C. gloeosporioides. The impact of nanofibers on avocado quality parameters was evaluated. The microstructures obtained with CG exhibited spherical capsules encapsulated the model compound (ß-carotene), providing thermal and photostability. FP, FP:Pul, and FP:PEO showed cylindrical, smooth, and thick helical fibers. Using WAXS, new peaks at angles below 10º were detected in FP:Pul and FP:PEO nanofibers, suggesting that FucoPol could affect the polymer structure of other materials with a secondary helical structure. Pullulan, CG:PEO, and FP:PEO nanofibers with M. caribbica were cylindrical, smooth, and homogeneous, offering thermal protection to the yeast. Pullulan nanofibers exhibited the highest M. caribbica viability and highest percentage of growth inhibition of the tested fungi. SBS showed homogeneous, continuous, and curly fibers, ensuring high M. caribbica viability on avocado surfaces under diferent conditions. Pullulan nanofibers with M. caribbica as preventive treatment completely inhibited C. gloeosporioides growth without affecting avocado quality parameters. This study represents the first investigation of pullulan, CG, and FP combined with PEO and pullulan for forming structures via electrohydrodynamic and aerohydrodynamic processes. The results underscore the high potential of nanofibers in the food industry, offering a promising alternative for postharvest fruit treatment against fungal diseases and contributing to reducing food loss in fruit production. / Agradezco al Consejo Nacional de Ciencia y Tecnología (CONACyT) por la beca número 754518 concedida para hacer posible el desarrollo de este proyecto de investigación. / Vázquez González, Y. (2024). Desarrollo de micro y nanofibras antifúngicas para el control de antracnosis en aguacate "Hass" (Persea americana Mill. cv. Hass) obtenidas por procesado electrohidrodinámico y aerohidrodinámico [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/206250 / Compendio

This thesis investigates the mechanisms behind natural silk spinning by integrating rheology, spectroscopy and small angle scattering to better understand this process and to guide our efforts towards mimicking Nature’s ways of producing high performance fibres. As a result of natural selection, arthropods such as spiders and moths have evolved the ability to excrete silk proteins in a highly controlled manner. Spun from liquid feedstocks, silk fibres are used ex vivo to build structures with mechanical properties currently unmatched by industrial filaments. As yet, relatively little attention has been directed to the investigation of spinning under biologically relevant conditions. To better understand how and why silk is spun, this thesis bridges the gap between liquid silk flow properties and structure development. To directly connect the two, I have developed and deployed novel experimental platforms that combine infrared spectroscopy and small angle scattering with rheology. This approach has clarified long-standing ambiguities on the structural root of silk’s apparently complex flow properties. Small angle scattering revealed the length scales involved in the flow induced solidification under a range of spinning conditions. Mo reover, infrared spectroscopy offered a unique perspective into silk’s formation process immediately after excretion. In a similar manner to the post-extrusion tuning of the properties of partly solidified spider silk filaments, this thesis has revealed that silkworm silk fibres are far from completely formed once excreted. One might describe the filaments of mulberry silkworm as seeded molten polymers that form its hydrogen bonding network and crystallises slowly on site. Consequently, it enlightens that post-spinning conditions are equally paramount for silkworm silk, giving an explanation for the relatively poorer mechanical properties. The comparison of silks from a range of species, allowed this hypothesis to be extended to wild silkworm silk. My insights into spinning had the fortuitous repercussion of facilitating silk fibre solubilisation leading to the development of better artificial silk feedstocks flowing like native silks. With these findings, I believe we are now in an improved position to conceive artificial fibres with properties rivalling those of Nature.

Various nano-fillers can introduce specific functions into polymer and expand their application areas. Myriad properties, such as mechanical, electrical, thermal, or magnetic properties can be combined with original polymer characteristics, including flexible, light weight, and ease of use. These composites can be used to produce multi-functional fibers as the next generation textile or fabrics. In this research, Polyacrylonitrile (PAN) is adopted as the main polymer with different nano-fillers, such as carbon nanotube (CNT), iron oxide nanoparticle, and graphene oxide nanoribbon (GONR). Using gel-spinning technology, PAN-based composite fibers are fabricated in single- or bi-component fibers. Fibers are also characterized for their structure, morphology, mechanical properties, as well as for their electrical, thermal, or magnetic properties. For example, bi-component fibers with polymer sheath and polymer-CNT core as well as polymer-CNT sheath and polymer core are processed. With electrical and thermal conductivity introduced by CNT, such bi-components fibers can be applied for wearable electronics or for thermal management. Joule-heating effect owing to applied electrical current on single component PAN/CNT fibers is also investigated. With controllable electrical conductivity and fiber temperature, this active functional fiber can be applied for temperature regulation fibers or new carbon fiber manufacturing process. Another example is magnetic fiber with superparamagnetic iron oxide nano-particles. These novel magnetic fibers with high strength can be used for actuator, inductors, EMI shielding, or microwave absorption. GONR is also discussed and used to reinforce PAN-based fibers. Several theoretical models are considered to analyze the observed results.

The process, structure, and property relationship of PAN fiber as a precursor to carbon fiber was studied. The limitations of stable spinning and property improvement associated with hot draw in solution spinning were found and quantified. Conditions were varied to generated precursor fiber up to the limit of draw, from which actual samples were collected for thermal conversion to carbon fiber. Samples of PAN and subsequent carbon fiber were characterized using tensile testing and x-ray analysis. The effects of draw on modulus and break stress, as well as the orientation of the crystalline structure of both parent precursor and resultant carbon fiber were found and related back to the quantified draw limit.

Cette thèse rapporte l’étude des propriétés de fibres composites polymère/nanotubes de carbone obtenues par voie fondu. Contrairement aux fibres produites jusqu’à présent par cette technologie, les fibres réalisées dans cette thèse sont conductrices. Les propriétés électriques sont étudiées en fonction de différents paramètres dont la température et les contraintes mécaniques. Par un modèle analytique, il est montré que l’étirement induit par leprocédé entraine une translation relative des nanotubes et une perte de contacts électriques.Ces fibres possèdent aussi des propriétés thermomécaniques originales comme des effets à mémoire de forme et à mémoire de température. Cette dernière est reflétée par un pic de contrainte générée à la température de déformation du matériau. Ces effets ont pu être mis en évidence sur des déformations de type traction et torsion. Même si ces effets sont gouvernés par le polymère, l’introduction des nanotubes apporte des améliorations des propriétés. / This thesis reports the study of the properties and structure of carbon nanotube / polymercomposite fibers obtained by melt spinning. By contrast to most fibers produced by thistechnology, the fibers produced in this thesis are electrically conductive. The conductivityproperties are studied as a function of various parameters including temperature andmechanical stress. It is shown that fiber drawing induced by the process leads to a relativetranslation of the nanotubes relative to each other and to a loss of electrical contacts. Ananalytical model accounts for this phenomenon and reproduces the experimental results.Polymer-nanotube fibers exhibit also particularly original thermomechanical properties suchas shape memory effects that are controllable by the programming process. Surprisingly, thefibers have a temperature memory reflected by a peak of the generated stress at thetemperature at which the materials has been programmed. These effects have beendemonstrated for various types of deformations including elongation and torsion. Althoughthese effects are governed by the properties of the polymer, it is shown that the introductionof nanotubes provides significant improvements of the thermomechanical properties.