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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Hygienic Property and Water Resistance of Waterborne Polyacrylate/Flower-like ZnO Composite Coatings

Bao, Yan, Gao, Lu, Ma, Jianzhong 28 June 2019 (has links)
Content: Polyacrylate as film-forming materials has been widely used in leather finishing, but its compactness significantly obstructs the hygienic property of upper leather. Therefore, considerable efforts have been made to endow polyacrylate with required properties. In this study, we demonstrated a facile and rapid sonochemical process to synthesis the flower-like ZnO nanostructures. The related morphology and structure of product were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Meanwhile, flower-like ZnO were introduced into the polyacrylate matrix by physical blending method, whose morphology, latex stability, water vapor permeability and water resistance were measured. The results showed that flower-like ZnO assembled by ellipsoid-like nanorods with the length of about 600 nm was successfully fabricated. The sizes of flower-like ZnO were 1.2 μm. According to SEM images, flower-like ZnO evenly dispersed were observed in composite matrix. Compared with pure polyacrylate, polyacrylate/flower-like ZnO composites exhibited the superior stability. Meanwhile, its water vapor permeability and water resistancewere increased by 52.91% and 53.13%, severally. The reason for this is that ZnO with rough structure can increase voids in polyacrylate film and thus improving hygienic property of polyacrylate film. Additionally, the hydrophilic groups on surface of ZnO can product the crosslinking with polyacrylate chains, which contributed to the enhancement of water resistance. Thus, a promising coating with hygienic property and water resistance for leather finishing agent was approved. Take-Away: 1. Polyacrylate/flower-like ZnO composites exhibited excellent hygienic property. 2. This composite coating achieves simultaneous enhancement in water vapor permeability and water resistance. 3. The morphology of ZnO can effect the properties of polyacrylate.
222

Extrakce antioxidantů z bezových květů a úchova extraktu pro další možné využití / Extraction of antioxidants from the elderberry blossom and preservation of the extract for further possible use

Krůzová, Sabina January 2018 (has links)
The thesis deals with the extraction of antioxidants from elder flowers and the way of storage obtained extract. The elder flowers which are obtained by cutting trees as a waste product and after their processing it could be used as an ingredient to cosmetics products for body and face skin or in a spa like additive to baths. In theoretical part are information about black elder, its botanical characteristics, utilization and about substances contained in it. There is also a chapter about lyophilization as a method which was used for concentration of extract. The last chapter describes theoretical information about liquid chromatography because this method was used for analysis of contents of extract. Experimental part describes optimalization steps in preparation of extract. It was found that the biggest content of polyphenolic compounds was when the proportion between flower and water was 1:10, optimal temperature of water for extraction is 100 °C and it was also found that the time of extraction don´t have any influence on content of polyphenols. Thanks to the lyophilization it was obtained dry light brown powder which is stable for long time. The lyophilizate was tested for some physical properties like pH, refractive index, solubility etc. There was also determined antioxidant activity by DPPH method and there was found quenching activity is 64,9 %. In determining of heavy metals in sample was found trace amounts of lead and chrome. By liquid chromatography was determined content of polyphenols, caffeic acid was in an amount 59,6 mgl1, chlorogenic acid 398 mgl1 and ferulic acid wasn´t detected. All of analysis was for 1% solution of extract because to cosmetic it could be just this amount to addition. In the last step was prepared a skin lotion with elder flower extract and it was tested for stability also was prepared an ointment from pork lard.
223

Determination Of The Gene Networks Controlling Sex Determination In Cucurbitaceae / Détermination des réseaux de gènes contrôlant la détermination du sexe chez les cucurbitacées

Abou Choucha, Fadi 22 June 2018 (has links)
La molécule de l’éthylène (C2H4) est le régulateur principal du sexe chez les cucurbites. Essentiellement, l’éthylène est connu pour son rôle promoteur dans le développement des carpelles et un rôle inhibiteur des étamines dans les fleurs du melon. L’interaction entre les biosynthétique gènes de l’éthylène (CmACS7, CmACS11, et CmACO3) et le facteur de transcription CmWIP1 détermine différentes formes du sexe chez le melon. Le rôle de ces gènes est bien étudié chez le melon. Cependant, le mécanisme qui contrôle l’initiation et la coordination de formation des étamines et des carpelles dans la fleur reste ambigu. En reposant sur l’importance de l’éthylène dans l’expression du sexe chez le melon, j’ai focalisé sur l’identification des gènes impliqués dans la voie signalisation éthylène-sexe. Au cours de la thèse, le criblage des mutants altérés dans la réponse à l’exogène éthylène nous facilitait d’identifier des nouveaux gènes impliqués dans la détermination du sexe chez la famille de Cucurbitacée. Pendant ma thèse j’ai isolé plus de 10 mutants insensibles à l’éthylène de différentes populations du melon. Deux mutants ont été isolés de deux populations monoïques indépendantes. Ces deux mutants provoquent une transition partielle et complète au melon andromonoïque dans la génération M2, respectivement. Un de ces deux mutants a été identifié et caractérisé. Deux autres mutants gsn106 et vat233 ont été criblés de deux populations andromonoïque, provoquent une transition complète et partielle à androïque melon, respectivement. En utilisant le séquençage à haute débit et les analyses génétiques j’ai essayé de cloner et caractériser ces gènes mutants. Par ailleurs, des autres mutants insensibles à l’éthylène sont en cours d’être phénotypes pour le phénotype du sexe. L’isolation et caractérisation des nouveaux gènes impliqués dans le déterminisme du sexe nous aidera pour mettre en place un model clair explant comment le sexe est contrôlé chez les plantes. / Ethylene (C2H4) is an important phytohormone in plants and the main sex regulator in the family Cucurbitaceae. As known, the ethylene promotes the carpel development and inhibits the stamens in the melon flower (Cucumis melo L.). The interplay of the biosynthesis genes (CmACS7, CmACS11, et CmACO3) and the transcription factor CmWIP1 generates different sexual forms in melon. The role of these genes in the sex expression is well studied. However, the mechanism that controls the initiation and coordination of stamen and carpel development in the flower remains ambiguous. Based on the importance of the ethylene in the sex determination, I aimed to isolate novel genes involved in the pathway ethylene-sex in the melon (Cucumis melo L.). For this purpose, I used the response to exogenous ethylene in the etiolated seedlings (known as the triple response phenotype) to isolate ethylene-insensitive mutants. During my thesis I isolated more than 10 ethylene-insensitive mutants from six EMS-mutagenised melon populations. Some of these mutants induced changes in the sex expression of the melon. . Two mutants were isolated from two independent monoecious populations (female and male flowers on the same plant) and induced a partial and a complete sexual transition to the andromonoecious melon in the second generation M2, respectively. One of them was cloned and characterized using Omics tools. Two other mutants (gsn106) and (vat233) screened from two independent andromonoecious melon (bisexual and male flowers on the same plant) populations, induced complete and partial sexual transitions into androecy (only male flowers), respectively. Using Next-Generation Sequencing (NGS) and the genetic analysis, we are trying to clone and characterise these mutants (gsn106) and (vat233). In the same way, we continue to observe others promising ethylene-insensitive mutants (vat306, vat175, and vat230) for the sex phenotype. The isolation and characterisation of novel genes involved in the sex determination will permit to provide a new and clear model explains of the sex determination mechanism in plants.
224

Floral Categorization in Bumblebees

Xu, Vicki 16 April 2020 (has links)
In nature, pollinators must navigate fields of resources presenting a variety of features, differing in shape, size, colour, etc. Foraging on a flower by flower basis is slow and maladaptive. Instead foragers must be able to differentiate between rewarding and unrewarding floral species while also generalizing learned information between flowers of the same species. The ability to categorize stimuli occurs on several levels of abstraction, laid out by Herrnstein (1990). In order to categorize objects, animals must first be able differentiate between them without memorizing each stimulus separately. Consequently, objects can be grouped by physical characteristics through perceptual categorization, or, on a more abstract scale, by the function they serve to the animal. This thesis explores the bees’ ability to categorize flowers, following the levels of categorization to answer two questions: Can bees form categories? And how abstract can their categorization become? There has been limited investigation previously in categorization in bees, and no research done on invertebrates addresses categorization beyond physical features. The bees’ ability to form categories was evaluated with four experiments of preference: 1) similar-but-different judgements; 2) perceptual categorization; 3) simple and mediated generalization; and 4) functional relevance. Results show firstly that bees can generalize characteristics within flower species, but also differentiate individual flowers. Secondly, bees can form perceptual categories, and while they rely on physical floral features for categorization, bees also demonstrated preliminary abilities for functional generalization as well. These results provide an explanation to natural foraging techniques adopted by the bees. The adaptive nature of categorization allows foragers to find resources more efficiently and better prepare in changing environments.
225

In vitro studies on the mechanisms of action of chamomile, myrrh and coffee charcoal – components of a traditional herbal medicinal product (Myrrhinil-Intest®)

Vissiennon, Cica 17 February 2015 (has links)
The traditional herbal medicinal product Myrrhinil-Intest® is a fixed herbal combination, which is marketed in Germany since 1959 and applied in medical practice for the treatment of gastrointestinal disorders such as functional diarrhea, irritable bowel syndrome and inflammatory bowel disease. It contains myrrh, which is described as the oleo-gum resin from mainly Commiphora molmol Engler (Burseraceae), coffee charcoal, which are the milled roasted to blackening outer seed parts of green dried Coffea Arabica Linné (Rubiaceae) fruits and chamomile flowers - the flower heads of Matricaria recutita Linné (Asteraceae). The clinical effectiveness of Myrrhinil-Intest® for the treatment of various gastrointestinal disorders was demonstrated in several clinical studies and is described in various experience reports, however its pharmacological profile is not fully elucidated. Within the present study the spasmolytic and anti-inflammatory potential of the components myrrh, chamomile and coffee charcoal was investigated. Therefore pharmacological, histological and molecular biological methods were utilised. Spasmolytic activity was characterised using isometric tension measurement with rat isolated small intestinal preparations. Anti-inflammatory potential was assessed with different methods using isolated rat small intestinal preparations and immune cell lines. Inflammation was induced with TNBS and LPS respectively. Additionally, the influence of the herbal components on the gene expression profile of native human macrophages after LPS/IFNγ stimulation was determined by microarray gene expression analysis. Chamomile flower and myrrh exerted spasmolytic effects, whereby the more pronounced spasmolytic effects of myrrh were mediated via calcium channel blockade. Myrrh and chamomile flower exerted anti-inflammatory effects.
226

Vliv atmosférických srážek na otevírání prašníků / The role of atmospheric precipitation in anther dehiscence

Kampová, Anna January 2020 (has links)
Anther dehiscence is an important process taking place at the end of the plant life cycle. This process consists of various follow-up steps which result in anther opening and pollen grains exposure. Good timing of the anther dehiscence must be synchronized with pollen grains maturation and flower opening. Atmospheric precipitation is a high-risk factor for the anther dehiscence. Male fitness of plants can be reduced when anthers open during poor weather conditions. The aim of this study was to investigate the effect of atmospheric precipitation, rain and dew, on Arabidopsis arenosa anther dehiscence. We observed that rain and dew led to a postponed final stage of the anther dehiscence. This caused delayed pollen release. The effect of aqueous and nonaqueous environment on the anther dehiscence was also tested. Experiments with transformation of A. arenosa using Agrobacterium tumefaciens were performed. Key words: anther dehiscence, flower opening, rain, dew, Arabidopsis arenosa, Agrobacterium tumefaciens, transformation
227

TOXICOLOGICAL INTERACTIONS BETWEEN THIAMETHOXAM, APHIDS, AND PREDATORY NATURAL ENEMIES

Esquivel Palma, Carlos Josue January 2019 (has links)
No description available.
228

Impact of Spatial Distance and Pollinators on Floral and Fruit Bacterial Communities of Solanum carolinense

Heminger, Ariel Renee 03 August 2023 (has links)
Fruits and flowers house microbial communities that are unique from the rest of the plant. While a great deal is known about a handful of symbiotic microbes associated with roots and leaves, the microbial communities of fruits and flowers have received considerably less attention. Fruits are reproductive tissues that house, protect, and facilitate the dispersal of seeds, and thus they are directly tied to plant reproductive success. Fruit and flower microbial communities may, therefore, also impact plant fitness. This dissertation examines how fruit bacterial communities, as determined using the 16S rRNA gene marker, are shaped across spatial and environmental gradients and the role of pollinators in shaping floral bacterial communities among natural populations of Solanum carolinense. There have been limited studies on how spatial distance influences bacterial communities found in and on fruit tissue and the role of pollinators in shaping floral bacterial communities. The first study addresses how bacterial communities in fruit change across similar environmental conditions at fine spatial scales (2 to 450 m). Overall, no differences were found in observed richness or bacterial community composition. Next, the role that generalist pollinators might play in shaping these communities was tested using pollinator exclusion cages. Here we found that generalist pollinators do not play a large role in shaping floral bacterial communities in Solanum carolinense. Comparing bacterial community diversity between caged and uncaged flowers, via PCoA we found no significant clustering of samples. In contrast, significant clustering was detected between flowers and bee pollen baskets. Together these results suggested that environmental factors may be more important in shaping floral bacterial communities. To test this, we sampled 9 populations along a 337 km latitudinal transect and again used the 16S rRNA gene to characterize bacterial communities. We did not identify a significant correlation between distance and bacterial community composition in either the total nor endophytic community in the fruit. Results from these studies suggest that while there is some evidence for environmental effects shaping fruit and flower communities, other factors such as host selection (e.g., secondary compounds in fruit) also likely play an important role in shaping bacterial communities. / Doctor of Philosophy / Fruit and flowers are directly tied to plant reproduction, yet little is known about the bacterial communities associated with these important organs, especially compared to other plant tissues. This dissertation aims to address gaps in our knowledge regarding how spatial distance and pollinators influence fruit and floral bacterial communities. Specifically, how does bacterial community composition (what bacteria taxa are present or not and how abundant the bacterial taxa are) change based on spatial distance. Studies were conducted at both fine (under 0.5 km) and broad (337 km) scales to determine if a pattern was observed between increasing distance and how distinct the bacterial community composition is. There was no significant correlation between spatial distance and bacterial community composition at fine spatial distances, however there were high levels of dissimilarity in the bacterial communities sampled across fine spatial scales. This led to the investigation of pollinators, which directly interact with flowers and may act as a source of bacterial community transmission in the flower and fruit bacterial communities as they move around the landscape. To address the role that pollinators play in shaping bacterial communities in the fruits an exclusion cage study was used to prevent pollinators from interacting with a subset of flowers. Pollen baskets (pollen that was collected by the pollinator and is found on the legs of pollinator) were also collected from pollinators to determine what bacteria may be present on the pollinator. Pollen baskets may also represent what bacteria may have been picked up by the pollinator at the site. It was observed that caged and uncaged samples were similar to one another, which suggest that pollinators were not adding new bacteria nor changing the bacterial composition in the flowers. Yet, the pollen baskets (from the pollinator) were unique from the caged and uncaged floral samples. To further investigate what factors may be at play in shaping the fruit bacterial community the transect was expanded to 337 km to determine if there was an observable relationship between spatial distance and bacterial community composition. The relationship between spatial distance and bacterial community composition was not significant in either the endophytic (internal bacterial community) or the total fruit bacterial community (which represented external and internal bacterial communities). Similar to the fine spatial scale study, there were high levels of dissimilarity in the bacterial community that was observed across sites. Results from these studies may suggest that there are other factors that play a larger role in shaping bacterial communities in fruit and flower tissue. These could include the host plant and the production of secondary compounds, which in some cases can act as antimicrobial compounds, and enhance or inhibit the growth of specific bacterial taxa. Environmental factors such as wind and rainfall may have influenced the bacterial community composition. It is likely that environmental factors play a role in shaping floral and fruit bacterial communities. However, it is still unclear what factors shape fruit and floral bacterial communities are. This study provides the foundation for future studies to address additional factors that shape fruit and flower bacterial communities.
229

A Comprehensive study on Federated Learning frameworks : Assessing Performance, Scalability, and Benchmarking with Deep Learning Model

Hamsath Mohammed Khan, Riyas January 2023 (has links)
Federated Learning now a days has emerged as a promising standard for machine learning model training, which can be executed collaboratively on decentralized data sources. As the adoption of Federated Learning grows, the selection of the apt frame work for our use case has become more important. This study mainly concentrates on a comprehensive overview of three prominent Federated Learning frameworks Flower, FedN, and FedML. The performance, scalability, and utilization these frame works is assessed on the basis of an NLP use case. The study commences with an overview of Federated Learning and its significance in distributed learning scenarios. Later on, we explore into the examination of the Flower framework in-depth covering its structure, communication methods and interaction with deep learning libraries. The performance of Flower is evaluated by conducting experiments on a standard benchmark dataset. Metrics provide measurements for accuracy, speed and scalability. Tests are also conducted to assess Flower's ability to handle large-scale Federated Learning setups. The same is carried out with the other two frameworks FedN and FedML also. To gain better insight into the strengths, limitations, and suitability of Flower, FedN, and FedML for different Federated Learning scenarios, the study utilizes the above stated comparative analysis on a real time use case. The possibilities for integrating these frameworks with current machine learning workflows are discussed. Furthermore, the final results and conclusions may help researchers and practitioners to make conversant decisions regarding framework selection for their Federated Learning applications. / <p>Det finns övrigt digitalt material (t.ex. film-, bild- eller ljudfiler) eller modeller/artefakter tillhörande examensarbetet som ska skickas till arkivet.</p><p>There are other digital material (eg film, image or audio files) or models/artifacts that belongs to the thesis and need to be archived.</p>
230

Revolutionaries and Prophets: Post-Oppositionality in Kathleen Alcalá's Sonoran Desert Trilogy

VonTress, Aurelia Ann 08 1900 (has links)
In this dissertation, I examine the Sonoran Desert trilogy by Kathleen Alcalá through the lens of post-oppositional theory as developed by AnaLouise Keating. Moving beyond the use of post-oppositional theory to analyze non-fiction works, I apply this theory instead to the fiction of Kathleen Alcalá—whose work appears in such anthologies as The Norton Anthology of Latino Literature. Alcalá, though well published, is underrepresented in contemporary literary criticism, as can be seen by the only eight entries under her name in the MLA International Bibliography. Therefore, I have chosen her most significant fiction work, her trilogy about the Sonoran Desert, as the perfect text upon which to map post-oppositional theory. Through analysis of her three novels, I show that her work is an ideal example of post-oppositionality in action and that her characters act as post-oppositional revolutionaries and prophets within the pages of the text. The first chapter outlines the parameters of the project. In Chapter 2, I argue that post-oppositionality can be seen in Alcalá through gender bending, looking at the characters of Membrillo and Manzana, Corey, and Rosalinda. In Chapter 3, I argue that the characters of Estela, La Señorita, and Magdalena are enacting post-oppositionality through their transcendence of traditional women's roles in sexuality. In Chapter 4, I argue that the female characters of the novels act as revolutionaries through their political and social agency—reaching out to other characters through such work as educating and writing. In Chapters 5 and 6, I feature my interviews with Alcalá and Keating, who were generous enough to speak with me over Zoom during lockdown. Finally, in the conclusion chapter, Chapter 7, I examine how post-oppositionality in the novels prepares the reader for post-oppositional action in reality. Throughout all of these chapters, I rely on other theories and historiographies such as gender theory (Judith Butler, Foucault, West and Zimmerman, etc.), the history of women's sexuality, and the roles of women in nineteenth century Mexico (looking especially at the works of Nancy LaGreca and Anna Macías).

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