No description available.

Non-volatile memory can keep the data without supplying power, and it is suitable for portable electronic products due to the advantage of low power consumption. In current industrial production, high-temperature and long-time process are necessary for the fabrication of non-volatile memory, which are heavy loadings on production capacity and lots cost. Therefore, decreasing the temperature of the process is a trend. Recently using the oxidation treatment of supercritical carbon dioxide fluid can efficiently decrease the temperature of the process. In this thesis, the mixture layer of Zn, Sn, and SiO2 is applied to reduce the temperature of process, and to employ the defects of ZnO and SnO2 as floating gate for electron storage to fabricate the nonvolatile memory device. Zn and Sn are applied due to the low temperature melting points. To ensure the layer of cosputtering with Zn and Sn to be able to successfully fabricate as nano material device, the process of traditional rapid temperature annealing treatment was applied for first step. The co-sputtered Zn-Sn-SiO2 thin film was deposited on the tunneling oxide layer, and then the thin film was treated with varied annealing temperature to precipitate ZnO and SnO2 nanocrystals. After that, the C-V measurement is applied to analyze the change of the electrical and material properties. Using a positive bias, the electrons are injected into the oxide layer, by the threshold voltage the offset is occurred, which is defined as the memory window of the memory effect, and the property of nonvolatile memory will be applied. In addition, no matter the charge is injected from the gate oxide or tunnel oxide, the defects position of DLTS¡¦s peak is with the same property. The supercritical carbon dioxide fluid technology has been performed to study the memory effect. The capability of electron injection, storages and the defect, in the storage layer were studied by the C-V measurement and DLTS. The experiment confirmed that the Zn-Sn alloy has the memory property after it been treated by the supercritical carbon dioxide fluid technology. It has shown that Zn can promote to the storage capability ability due to the formation of deep level defects of SnO2 from the DLTS spectra. A new species is found at 0.93 eV with low activation energy and high capability of electron storage. The defect formation mechanism of Zn, ZnO, Zn-O-Si, Sn, and SnO are analyzed by found by the XPS and DLTS. The device fabrication using Zn-Si alloy and supercritical carbon dioxide fluid technology has the potential to reduce the process temperature and to improve the memory property of nonvolatile memory device.

Vinyl acetate (VA) is an important monomer used in the production of paints, surface coatings and adhesives. Synthesis of VA is usually carried out over supported Pd alloy catalysts with a selectivity as high as 96% and described as C2H4 + CH3COOH + ½ O2 -> C2H3OOCCH3 + H2O Although the VA synthesis reaction has been industrially carried out for many years, the nature of the active sites and the reaction mechanism is still unclear. The goal of this study was to acquire a fundamental understanding of the VA reaction mechanism by carrying out detailed kinetic and spectroscopic investigations on single crystals and supported Pd catalysts, and to detail the role of alloying in optimizing the selectivity of this important industrial reaction. A combination of surface science techniques and kinetic measurements has been used to address the mechanism. Supported catalysts, 1 wt% Pd/SiO2 and 5 wt% Pd/SiO2, and 1 wt% Pd-0.5 wt% Au/SiO2, were prepared by an incipient wet-impregnation method and characterized using XRD and TEM. On Pd-only catalysts the reaction rates were found to be: Pd(100) < 5 wt% Pd/SiO2 (dpd = 4.2 nm) < 1 wt% Pd/SiO2 (dpd = 2.5 nm). Particle size-dependence of the reaction rates is evident for the Pd-only catalysts, which suggests a degree of structure sensitivity of the reaction. There is an increased availability of uncoordinated, edge atoms on small particles. With a Pd single crystal, fewer less-coordinated surface sites are present compared to a comparable area on a small Pd particle on a supported Pd catalyst. The formation of Pd carbide (PdCx) during the synthesis of VA was investigated over Pd/SiO2 catalysts with two different Pd particle sizes, as well as over a Pd-Au/SiO2 mixed-metal catalyst. XRD data indicate that smaller Pd particles show greater resistance to the formation of PdCx. The alloying of Au with Pd is apparently very effective in preventing PdCx formation in Pd-based catalysts for VA synthesis. Addition of Au to Pd/SiO2 catalysts significantly enhances the VA formation rate and selectivity. Infrared reflection absorption spectroscopy (IRAS) of CO on Pd/Au(100) and Pd/Au(111) confirms the presence of Pd as isolated monomers on a Au-rich surface. A pair of Pd monomers is the most favorable active site for the formation of VA. The spacing between the two active isolated Pd atoms is critical and is demonstrated by the relative rates of VA formation on Pd/Au model catalysts, i.e. Pd/Au(111) < Pd/Au(100). The role of Au is to isolate the surface Pd atoms and thus suppress the formation of by products, CO and CO2. A pair of Pd monomers required for VA synthesis is further confirmed by the results from model studies of Sn-Pd.

New environmental regulations enforce the electronic industry to replace Pb-Sn solder due to Pb could contaminate our environment. Pure Sn has good material properties such as solderability, conductivity and anti-corrosion. Pure Sn is a good candidate to replace Pb-Sn solder. One of the disadvantages of pure Sn is the whisker growth phenomenon. Whisker problem has become a major concern in electronic industry due to the trend toward component miniaturization and pitch reduction. It is well understood that the root cause for tin whisker growth is the compressive stress within the tin layer. In the literature, the main stress sources are, (1) the intermetallic layer induced interface stress, (2) the difference of thermal expansion coefficient between Sn layer and substrate and (3) the mechanical residual stress from trim-form operation after tin plating. In our study, we used the electrochemical electrolysis method and Cross-section Polisher (CP) to examine the tin whisker growth mechanism. In the result, we can clearly show the Cu6Sn5 phase grow up in the tin grain boundary regions and demonstrate that the Cu6Sn5 phase formation is the main cause of the tin whisker growth. We also discuss the relationship of tin whisker growth and tin-plating process parameters that include the temperature effect; Ni underlay effect and tin-plating bath effect. For the temperature effect, the Cu6Sn5 is the major phase at 150¢XC aging. The mechanism behind its growth mechanism was grain boundary diffusion at the earlier stage and then the bulk diffusion in the later stage. The application of 150¢XC post-heat treatment could drive the bulk diffusion and form a layer type Cu6Sn5 phase to eliminate the whisker growth. For the Ni underlay effect, the Ni underlay can block the Cu atom diffusion to the tin layer and changed the tin layer stress state from compressive to tensile. Therefore, the tin whisker can be eliminated. For the tin-plating bath effect, in the sulfuric acid base and uses Triton X-100 as the surface active agent, may transform the whisker type to particular tin grain type. Thus, this tin-plating solution can restrain the tin whisker growth.

No description available.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第18982号 / 工博第4024号 / 新制||工||1620 / 31933 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 田中 功, 教授 酒井 明, 教授 邑瀬 邦明 / 学位規則第4条第1項該当

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction, September 11-13, 2013, Sapporo, Japan (EASEC-13)

Titanium is well known for its excellent properties, such as high strength-to-weight ratio and outstanding corrosion resistance. However the high cost of this metal has confined its applications to those mostly within the aerospace and military industries. The high purchase price of titanium is primarily driven by the need for intricate metal extraction processes, as well as the sensitivity towards conventional metal working operations. Among the potential solutions, powder metallurgy (P/M) technology provides an economical approach to bring down the price of finished titanium products. However, there are still many problems, such as the residual porosity in the sintered body, that need to be overcome. In this thesis, a fundamental study was carried out focusing on the P/M press-and-sinter technique, using commercially pure titanium (CP Ti) as well as two binary titanium alloys, namely Ti-Ni and Ti-Sn. The influence of several processing parameters including compaction pressure, lubricant type/concentration, sintering time/temperature were performed on both the CP and binary systems. The principal tools utilized for mechanical characterization were hardness and tensile testing, whereas optical microscopy, x-ray diffraction (XRD), and scanning electron microscopy were employed to identify the microstructural features present. Press-and-sinter P/M strategies were successfully developed for all of the blends studied. For CP-Ti, a maximum tensile strength >750MPa and near full theoretical density (~99%) were achieved. Transitions in the size and the size distribution of pores and ?-Ti grains were also observed and quantified. It was found these transitions, as well as the powder impurities present (i.e. oxygen and carbon), greatly influenced the final mechanical properties. In the case of the binary alloys, it was shown that liquid phase sintering (LPS) significantly improved the sintered density for the Ti-10%Ni composition, when sintered at l100°C. A eutectic microstructure (CP-Ti + Ti2Ni), coupled with grains of CP-Ti, were identified as the principal phases present. On the other hand, the Ti-Sn alloys only showed a modest increase in sintered density compared to the CP-Ti, owing to the high solubility of Sn in Ti. In terms of crystal structure, XRD highlighted that the Sn containing samples were fully CP-Ti.

全球鋼鐵需求及供給的最大國－中國大陸，已進入到成長趨緩的階段，同時歐美的鋼鐵前景亦是呈現疲弱或趨緩的階段，然而依賴出口至前三個地區的台灣來說，無疑是一項衝擊。也因如此，台灣於近年來，為能提升台灣鋼鐵產業的競爭力，已大幅開放大陸地區的鋼鐵進口，然大陸鋼鐵項目的進口多寡，對於台灣鋼鐵產業的發展存在著多少的影響，即成為台灣鋼鐵產業所亟需討論課題。因此，本研究以大陸鋼鐵進口與台灣鋼鐵產業的關係為研究主軸，討論台灣鋼鐵產業發展的可行作為，策訂一個合宜台灣鋼鐵產業的產業發展模式，據以提高台灣鋼鐵產業的競爭力。 因此，本研究依據分析方法的應用，探討大陸地區鋼鐵進口的政策施行，對台灣鋼鐵產業的發展所帶來的影響，依研究分析的結果得到以下幾項的研究發現： 一、台灣粗鋼的產量未呈現大幅成長的趨勢； 二、鋼筋與型鋼的生產量與銷售量具有高度相關性； 三、台灣鋼鐵產品已由半成品製造轉而鋼鐵成品的製造； 四、大陸鋼鐵進口對台灣下游鋼鐵廠商有正面的互利關係； 五、市場區隔對於台灣鋼鐵產業發展有正面的幫助。

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-12-04T20:41:48Z No. of bitstreams: 1 KayoDiogenesDeAzevedoSilva_DISSERT.pdf: 2312119 bytes, checksum: 0a5f0d4a0645de7bdb4ab990bbb4f59d (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-12-07T20:45:07Z (GMT) No. of bitstreams: 1 KayoDiogenesDeAzevedoSilva_DISSERT.pdf: 2312119 bytes, checksum: 0a5f0d4a0645de7bdb4ab990bbb4f59d (MD5) / Made available in DSpace on 2017-12-07T20:45:07Z (GMT). No. of bitstreams: 1 KayoDiogenesDeAzevedoSilva_DISSERT.pdf: 2312119 bytes, checksum: 0a5f0d4a0645de7bdb4ab990bbb4f59d (MD5) Previous issue date: 2017-07-31 / A doen?a de Parkinson (DP) ? uma patologia neurodegenerativa que acomete principalmente indiv?duos do sexo masculino com o avan?ar da idade. A DP se caracteriza por diversos sintomas motores como tremores, bradicinesia, rigidez e altera??es posturais. Al?m destes, sintomas cognitivos como d?ficits de aten??o e mem?ria, dem?ncia e altera??es de humor tamb?m est?o presentes. ? poss?vel perceber marcada mudan?a na arquitetura do sono de pacientes com DP. O horm?nio melatonina sintetizado principalmente pela gl?ndula pineal localizada no Epit?lamo ? considerado um dos horm?nios que induzem a fase de sono dos organismos. Sua a??o ocorre ap?s se ligar a receptores espec?ficos, MT1 e MT2. No presente estudo foram utilizados 15 ratos machos de meia idade (10 meses) da esp?cie Wistar, divididos em dois grupos denominados de Controle (CTR) e Reserpina (RES). Esses animais foram submetidos a um protocolo cr?nico de 20 inje??es de reserpina, com o intuito de criar sintomatologias semelhantes a DP. Durante o protocolo experimental os animais foram avaliados atrav?s de teste de catalepsia. Com o fim do tratamento os animais foram sacrificados e submetidos a procedimento imunistoquimico para identifica??o dos receptores MT1 e MT2 em 5 ?reas do sistema nervoso central relacionadas diretamente com o ciclo do sono e com sintomas mais evidentes da DP, sendo elas, NE, NSQ, VLPO, SN e ZSPV. Nossos resultados mostraram que durante o per?odo de tratamento os animais do grupo reserpina apresentaram consider?vel e progressivo d?ficits motores que se acentuaram nos dias sete, oito, nove e dez de inje??es. Nossas analises imunoistoqu?micas mostraram que ocorre significativa redu??o da express?o de receptores de melatonina nos animais reserpina em todos os n?cleos avaliados, entretanto, novos estudos s?o necess?rios para uma melhor compreens?o do real motivo dessa diminui??o de express?o de receptores e se esta diminui??o tem efeito significativo nas altera??es do sono verificadas nos pacientes com DP. / Parkinson's disease (PD) is a neurodegenerative disorder that mainly affects males with advancing age. PD is characterized by several motor symptoms such as tremors, bradykinesia, stiffness and postural changes. In addition to these, cognitive symptoms such as attention and memory deficits, dementia and mood changes are also present. It is also possible to notice a marked change in the sleep architecture of patients with PD. The hormone melatonin synthesized mainly by the pineal gland located in the thalamus is considered one of the hormones that induce the sleep phase of the organisms. Its action occurs after binding to specific receptors, MT1 and MT2. In the present study, 15 male Wistar rats (10 months) were divided into two groups called Control (CTR) and Reserpine (RES). These animals were submitted to a chronic protocol of 20 injections of reserpine, in order to create symptoms similar to PD. During the experimental protocol the animals were evaluated by catalepsy test. At the end of the treatment the animals were sacrificed and submitted to an immunohistochemical procedure to identify the MT1 and MT2 receptors in 5 areas of the central nervous system related directly to the sleep cycle and with more evident symptoms of PD, VLPO, SN and ZSPV. Our results showed that during the period of treatment the animals of the reserpine group presented a considerable and progressive motor deficit that were accentuated on days seven, eight, nine and ten of injections. Our immunohistochemical analyzes have shown that there is a significant reduction in the expression of melatonin receptors in the reserpine animals in all evaluated nuclei, however, new studies are necessary to better understand the real reason for this decrease in receptor expression and whether this decrease has a significant effect on Observed in patients with PD.