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Étude de la neurotoxicité d’un Polluant Organique Persistant chez le rat : effets à court et à long terme de l’inhalation répétée de fluorène sur le développement sensori-moteur du jeune et le comportement à l’âge adulte / Neurotoxicity of a Persistent Organic Pollutant in rat : short- and long-term effects of the repeated inhalation of fluorene on sensorimotor development in the offspring and behavior at adulthoodPeiffer, Julie 12 December 2011 (has links)
La pollution atmosphérique est omniprésente du fait de nombreuses sources émettrices de composés chimiques. Dans ce contexte, les Hydrocarbures Aromatiques Polycycliques (HAP) sont largement diffusés dans l’air et ont déjà montré des effets délétères sur la santé.Ce travail a consisté en l’évaluation de la neurotoxicité du fluorène, composé choisi comme molécule représentative de la pollution liée aux HAP, chez le rat adulte exposé par voie i.p., par voie orale ou par inhalation. Le modèle d’exposition par inhalation a ensuite été appliqué à l’étude des effets du polluant sur le développement sensori-moteur et l’activité comportementale de l’animal exposé in utero ou au cours de la lactation.Ces études ont montré que le fluorène était susceptible d’affecter le niveau d’anxiété et l’activité locomotrice du rat adulte exposé directement et indirectement au polluant, et n’avait aucun effet sur les capacités d’apprentissage. En revanche, aucune atteinte majeure de la maturation des fonctions sensori-motrices n’a été mise en évidence. L’analyse de la présence du composé et de trois de ses métabolites a par ailleurs montré que le polluant était capable de traverser la barrière hémato-encéphalique et d’être métabolisé au niveau du cerveau. Les réponses physiologiques et comportementales étant variables entre les études, les effets induits par le fluorène dépendent donc de la voie d’entrée, du niveau de contamination et du moment d’exposition.Ces résultats ont ainsi révélé chez l’animal la toxicité comportementale du fluorène à des niveaux de contamination réalistes, confirmant ainsi le risque sanitaire de l’exposition aux HAP tout au long de la vie des individus / Actually air pollution is ubiquitous due to the emission of chemical compound from many sources. In this context, Polycyclic Aromaric Hydrocarbons (PAH)related compounds are widely distributed in the air and have shown deleterious health effects.Fluorene was chosen as a representative compound of PAHs pollution. This work consisted in the evaluation of its neurotoxic effects in adult animals, exposed i.p., orally or by exposure nose-only. The inhalation model of exposure was then applied to the study of its effects on sensorimotor development and on behavioral activity of animals exposed in utero or during lactation.The results showed that fluorene is able to induce behavioral changes in adult animals exposed directly or indirectly on the level of anxiety and the locomotor activity, whereas no effect on learning and memory abilities has been observed. However, no defect on the development of motor and sensory functions was demonstrated. Furthermore, the analysis of the presence of the compound and three of its metabolites showed that the pollutant was able to cross the blood brain barrier and can be metabolized in the brain. Moreover, variations have been observed concerning behavioral and physiological responses between studies, showing that effects induced by fluorene are dependent on the way of administration, the level of contamination and the time of exposure.In conclusion, these results demonstrate in animals the behavioral toxicity of fluorene at levels of contamination corresponding to human cases of exposure, confirming so the risk of PAH exposure throughout life
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床墊產業之消費者網路口碑研究 / A Study on Consumer’s e-Word-of-Mouth in Taiwanese Mattress Industry林天瀚 Unknown Date (has links)
隨著經濟成長,高度競爭的生活環境造成人們睡眠品質不佳或失眠,多半是深受入睡困難、淺眠和早醒等困擾。因此,對於現代人逐漸願意投資在寢具和床墊產品只求一夜好眠。
床墊是為耐久財,生命週期長且消費者感知風險高,因此大多消費者在購買前會先進行相關資訊蒐集。網路的普及使得商品資訊在網路上公開,使得網路成為消費者購物前蒐集資訊的主要管道。而隨著web2.0的興起,消費者在網路上分享產品資訊的網路口碑有了爆炸性的增加,產生了讓廠商無法忽視的網路口碑效應。透過網路口碑的分析可以了解消費者與市場需求,提供廠商未來修正整體經營策略。
本研究透過網路蒐集網路口碑進行內容分析法,瞭解消費者選購床墊的決策流程以及對國內外高價品牌床墊的評價。從研究結果可以發現,近四成的消費者是為了改善睡眠品質而產生購買床墊的需求。實體通路及網路是消費者主要蒐集資訊的管道。在評估床墊時,消費者重視床墊品質、價格以及軟硬度,他們在意床墊和彈簧的設計以及床墊軟硬度。而有近五成五的消費者是偏好較硬床墊。近九成九的購買管道為品牌床墊專賣店和一般床墊經銷通路居多。約1%的消費者由於網路購物的七天鑑賞期而選擇在網路購物平台購買。近七成五的消費者購買後表示滿意,近二成五的消費者購後仍不滿意床墊與彈簧的設計與材質,以及依舊腰酸背痛等。
消費者對於國內外床墊品牌的正面口碑多於負面口碑,其中消費者對席伊麗品牌形象最佳,負面評論少。而消費者對本土床墊品牌,如:德泰彈簧床、老K牌彈簧床和10 Days的品質也有正面的評價,但對於品牌形象與經營則保持負面的態度,建議未來應針對加強品牌權益的目標,調整行銷策略。 / With economic growth, a highly competitive environment results people in poor quality sleep or insomnia. Most of them suffer from difficulty in falling asleep, light sleep and wake early. Therefore, people are more and more willing to invest in bedding, pillow and matress just for a good quality sleep.
Due to the mattresses are durable goods with long product life cycle and perceived risk, consumers usually spend a lot of time to study the mattresses before purchasing. On the other hand, with the universal of the Internet and the growth of web2.0, the blooming e word-of-mouths (eWOM) makes consumer tend to uderstand products in advance by reading comments. That indeed cause a serious effect on eWOM for firms who should not ignore. Through analyzing the eWOM, firms could understand the trend on the demand side then modify their strategies.
This study collected eWOM from the Internet and use content analysis to understand consumer purchase decision process as well as the consumers’ insights into upscale mattresses. From the results, we could know that almost 40% of consumers buy a new mattress for improving sleeping quality. They usually collect the necessary information by visiting physical channels and surfing on the Internet. They evaluate the mattresses quality, price, softness and firmness. They care about mattresses and springs’ design and matieral. Almost 55% of consumers prefer to buy a firm mattress. Almost 99% of consumers buy mattresses at the physical channels. Rest of consumers buy mattresses on e-commerce due to the 7-days return warranty. Almost 75% of consumers feel satisfied after purchasing. Rest of them are not satisfied at the mattresses and springs’ design and material and uncomfortableness.
Consumers gave more positive comments than negative comments on the selected mattresses brands. Sealy had a reputation on its brand image and quality; King Koil, The-Tai Mattress, Kingbed, Tempur and 10 Days are all well-know for their quality as well, but still had some negative comments on the brand image and price. After the eWOM studies on each selected brand, this study gave suggestions to each brand for its future marketing strategy.
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PREFERENTIAL MICROSTRUCTURAL PATHWAYS OF STRAIN LOCALIZATION WITHIN NICKEL AND TITANIUM ALLOYSJohn J Rotella (11811830) 20 December 2021 (has links)
<p>Modern structural materials
utilize tailored microstructures to retain peak performance within the most
volatile operating conditions. Features such as grain size, grain boundary (GB)
character and morphology and secondary phases are just a few of the tunable
parameters. By tailoring these types of microstructural features, the
deformation behavior of the material is also altered. The localization of
plastic strain directly correlated to material failure. Thus, a systematic
approach was utilized to understand the effect of microstructural features on
the localization of plastic deformation utilizing digital image correlation
(DIC). First, at the macroscopic scale, strain accumulation is known to form
parallel to the plane of maximum shear stress. The local deviations in the
deformation pathways at the meso-scale are investigated relative to the plane
of maximum shear stress. The deviations in the deformation pathways are
observed to be a function of the accumulated local plastic strain magnitude and
the grain size. Next, strains
characterized via DIC were used to
calculate a value of incremental slip on the active slip systems and identify
cases of slip transmission. The incremental slip was
calculated based on a Taylor-Bishop-Hill algorithm, which determined a
qualitative assessment of deformation on a given slip system, by satisfying
compatibility and identifying the stress state by the principle of virtual
work. Inter-connected slip bands, between neighboring grains, were shown to
accumulate more incremental slip (and associated strain) relative to slip bands
confined to a single grain, where slip transmission did not occur. These
results rationalize the role of grain clusters which lead to intense strain
accumulation and thus serve as potential sites for fatigue crack initiation.
Lastly, at GB interfaces, the effect of GB morphology (planar or serrated) on
the cavitation behavior was studied during elevated temperature dwell-fatigue
at 700 °C. The resulting γ′ precipitate structures were characterized near GBs
and within grains. Along serrated GBs coarsened and elongated <a>γ′ </a>precipitates formed and consequently created adjacent
regions that were denuded of γ′ precipitates. Dwell-fatigue experiments were
performed at low and high stress amplitudes which varied the amount of imparted
strain on the specimens.<a> Additionally, the regions
denuded of the γ′ precipitates were observed to localize strain and to be
initial sites of cavitation.</a> <a>These results present a
quantitative strain analysis between two GB morphologies, which provided the
micromechanical rationale for the increased proclivity for serrated GBs to form
cavities.</a></p>
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