Cost Reduction of Permanent Magnet Synchronous Machines

Electrical machine drives are the most electrical energy-consuming systems worldwide. The largest proportion of drives is found in industrial applications. There are, however many other applications that are also based on the use of electrical machines, because they have a relatively high efficiency, a low noise level, and do not produce local pollution. Electrical machines can be classified into several categories. One of the most commonly used electrical machine types (especially in the industry) is induction motors, also known as asynchronous machines. They have a mature production process and a robust rotor construction. However, in the world pursuing higher energy efficiency with reasonable investments not every application receives the advantage of using this type of motor drives. The main drawback of induction motors is the fact that they need slipcaused and thus loss-generating current in the rotor, and additional stator current for magnetic field production along with the torque-producing current. This can reduce the electric motor drive efficiency, especially in low-speed, low-power applications. Often, when high torque density is required together with low losses, it is desirable to apply permanent magnet technology, because in this case there is no need to use current to produce the basic excitation of the machine. This promotes the effectiveness of copper use in the stator, and further, there is no rotor current in these machines. Again, if permanent magnets with a high remanent flux density are used, the air gap flux density can be higher than in conventional induction motors. These advantages have raised the popularity of PMSMs in some challenging applications, such as hybrid electric vehicles (HEV), wind turbines, and home appliances. Usually, a correctly designed PMSM has a higher efficiency and consequently lower losses than its induction machine counterparts. Therefore, the use of these electrical machines reduces the energy consumption of the whole system to some extent, which can provide good motivation to apply permanent magnet technology to electrical machines. However, the cost of high performance rare earth permanent magnets in these machines may not be affordable in many industrial applications, because the tight competition between the manufacturers dictates the rules of low-cost and highly robust solutions, where asynchronous machines seem to be more feasible at the moment. Two main electromagnetic components of an electrical machine are the stator and the rotor. In the case of a conventional radial flux PMSM, the stator contains magnetic circuit lamination and stator winding, and the rotor consists of rotor steel (laminated or solid) and permanent magnets. The lamination itself does not significantly influence the total cost of the machine, even though it can considerably increase the construction complexity, as it requires a special assembly arrangement. However, thin metal sheet processing methods are very effective and economically feasible. Therefore, the cost of the machine is mainly affected by the stator winding and the permanent magnets. The work proposed in this doctoral dissertation comprises a description and analysis of two approaches of PMSM cost reduction: one on the rotor side and the other on the stator side. The first approach on the rotor side includes the use of low-cost and abundant ferrite magnets together with a tooth-coil winding topology and an outer rotor construction. The second approach on the stator side exploits the use of a modular stator structure instead of a monolithic one. PMSMs with the proposed structures were thoroughly analysed by finite element method based tools (FEM). It was found out that by implementing the described principles, some favourable characteristics of the machine (mainly concerning the machine size) will inevitable be compromised. However, the main target of the proposed approaches is not to compete with conventional rare earth PMSMs, but to reduce the price at which they can be implemented in industrial applications, keeping their dimensions at the same level or lower than those of a typical electrical machine used in the industry at the moment. The measurement results of the prototypes show that the main performance characteristics of these machines are at an acceptable level. It is shown that with certain specific actions it is possible to achieve a desirable efficiency level of the machine with the proposed cost reduction methods.

Spin-electromagnetic waves spectra in multiferroic heterostructures

This work devotes to the theoretical investigations of spin-electromagnetic waves (SEW) propagating in a thin-film multiferroic structures that were composed of a slot-line and structures with several ferrite films. In contrast to earlier works, the spin-electromagnetic waves in the investigated structures are originated from two different electrodynamics coupling. The first one is coupling of the electromagnetic wave localized mainly in the slot-line with the spin wave excited mostly in the ferrite film. The second one is coupling of two spin waves in the different ferrite films separated by a thin ferroelectric film. For theoretical analysis of SEWs propagation in such kind of structures theories of their eigen-wave spectra were developed. Spectra of SEW in the investigated structures were calculated and analyzed. The range of electric and magnetic tunability of dispersion characteristic were investigated. Spectra of SEW in the investigated multiferroic structures are used for investigation of transfer function of periodic structures.

Cl- and regulation of pH by MDCK-C11 cells

The interaction between H+ extrusion via H+-ATPase and Cl- conductance was studied in the C11 clone of MDCK cells, akin to the intercalated cells of the collecting duct. Cell pH (pHi) was measured by fluorescence microscopy using the fluorescein-derived probe BCECF-AM. Control recovery rate measured after a 20 mM NH4Cl acid pulse was 0.136 ± 0.008 pH units/min (dpHi/dt) in Na+ Ringer and 0.032 ± 0.003 in the absence of Na+ (0 Na+). With 0 Na+ plus the Cl- channel inhibitor NPPB (10 µM), recovery was reduced to 0.014 ± 0.001 dpHi/dt. 8-Br-cAMP, known to activate CFTR Cl- channels, increased dpHi/dt in 0 Na+ to 0.061 ± 0.009 and also in the presence of 46 nM concanamycin and 50 µM Schering 28080. Since it is thought that the Cl- dependence of H+-ATPase might be due to its electrogenic nature and the establishment of a +PD (potential difference) across the cell membrane, the effect of 10 µM valinomycin at high (100 mM) K+ was tested in our cells. In Na+ Ringer, dpHi/dt was increased, but no effect was detected in 0 Na+ Ringer in the presence of NPPB, indicating that in intact C11 cells the effect of blocking Cl- channels on dpHi/dt was not due to an adverse electrical gradient. The effect of 100 µM ATP was studied in 0 Na+ Ringer solution; this treatment caused a significant inhibition of dpHi/dt, reversed by 50 µM Bapta. We have shown that H+-ATPase present in MDCK C11 cells depends on Cl- ions and their channels, being regulated by cAMP and ATP, but not by the electrical gradient established by electrogenic H+ transport.

Fatigue in a cohort of geriatric patients with and without Parkinson's disease

We evaluated the frequency of fatigue in geriatric patients with and without Parkinson's disease (PD) and correlated it with depression and excessive daytime sleepiness. We evaluated 100 patients from Hospital São Paulo, 50 with PD from the Neurologic Outpatient Clinic and 50 with non-neurologic diseases or oncologic diseases from the Geriatric Outpatient Clinic (controls). All patients who scored 28 or more on the Fatigue Severity Scale (FSS) were considered to have fatigue. Also, all patients were submitted to a structured interview to diagnose depression by the criteria of the American Psychiatric Association (DSM-IV, 4th version) and were evaluated by the Modified Impact of Fatigue Scale and the Epworth Sleepiness Scale (ESE) to detect excessive daytime sleepiness. Demographic and disease details of all PD patients were recorded and the patients were examined and rated by the Unified Parkinson's Disease Rating Sale (UPDRS) and Hoehn-Yahr staging. Frequency of fatigue (FSS ≥28) was 70% for PD and 22% for controls. Twenty of 35 PD patients with fatigue had concomitant depression. Compared to controls, PD patients were found more frequently to have depression by DSM-IV criteria (44 vs 8%, respectively) and excessive daytime sleepiness by the ESE (44 vs 16%), although only depression was associated with fatigue. Fatigue was more frequent among depressed PD and control patients and was not correlated with PD duration or with UPDRS motor scores. ESE scores did not differ between patients with or without fatigue.

Protection against neurotoxicity by an autophagic mechanism

The objective of the present study was to investigate the effects of 3-n-butylphthalide (NBP) on a 1-methyl-4-phenylpyridinium (MPP+)-induced cellular model of Parkinson’s disease (PD) and to illustrate the potential mechanism of autophagy in this process. For this purpose, rat PC12 pheochromocytoma cells were treated with MPP+ (1 mM) for 24 h following pretreatment with NBP (0.1 mM). Cell metabolic viability was determined by the MTT assay and cell ultrastructure was examined by transmission electron microscopy. The intracellular distribution and expression of α-synuclein and microtubule-associated protein light chain 3 (LC3) were detected by immunocytochemistry and Western blotting. Our results demonstrated that: 1) NBP prevented MPP+-induced cytotoxicity in PC12 cells by promoting metabolic viability. 2) NBP induced the accumulation of autophagosomes in MPP+-treated PC12 cells. 3) Further study of the molecular mechanism demonstrated that NBP enhanced the colocalization of α-synuclein and LC3 and up-regulated the protein level of LC3-II. These results demonstrate that NBP protects PC12 cells against MPP+-induced neurotoxicity by activating autophagy-mediated α-synuclein degradation, implying that it may be a potential effective therapeutic agent for the treatment of PD.

Influência da embalagem de atmosfera modificada e do tratamento com cálcio na cinética de degradação de ácido ascórbico e perda de massa em goiabas (Psidium guajava L.)

Goiabas de mesa (var. Pedro Sato) no estádio verde maturo foram armazenadas a 8°C (85-95% UR) por 49 dias. Uma parte das amostras foi tratada com solução de cloreto de cálcio 2% (p/v) e o restante permaneceu sem tratamento. Posteriormente, foram embaladas individualmente em dois tipos de embalagem de atmosfera modificada (CryovacÒ PD-900 e CryovacÒ PD-961). Goiabas sem embalagem e não tratadas com cálcio, mantidas à mesma temperatura de 8°C serviram como controle. Foram realizadas análises de perda de massa, acidez titulável, teores de sólidos solúveis totais e ácido ascórbico. Os frutos embalados apresentaram taxas de perda de massa menores que os sem embalagem (p<0,05). Os frutos tratados com cálcio não apresentaram diferença na taxa de degradação de ácido ascórbico em relação aos não tratados e os frutos embalados com PD-900 apresentaram retenção de ácido ascórbico maior. Após 4 semanas, as goiabas sem embalagem apresentaram-se impróprias para consumo, devido ao murchamento e ataque de fungos, enquanto que as embaladas estavam em bom estado. Após a sexta semana, apenas os frutos embalados com PD-900 sem tratamento com cálcio estavam próprios para consumo. A embalagem de atmosfera modificada reduziu a perda de massa e ácido ascórbico e prolongou a vida-de-prateleira do produto. O emprego de cálcio não afetou as características analisadas.

Influência de diferentes embalagens de atmosfera modificada sobre a aceitação de uvas finas de mesa var. Itália mantidas sob refrigeração

Foi feito um estudo sobre o comportamento de uvas finas de mesa (Vitis vinifera L.) var. Itália frente à armazenagem refrigerada e à utilização de embalagem, para aumentar a vida-de-prateleira. Cachos da uva no estádio verde maduro foram embalados individualmente em três diferentes filmes plásticos (Cryovac® PD-900; Cryovac® PD-955 e Cryovac® PD-961EZ ) de alta permeabilidade ao oxigênio e ao gás carbônico e armazenados a 1ºC (85-95% UR) por 63 dias e a 25ºC (80-90% UR) por 21 dias; frutas sem embalagem serviram de controle. Ao longo da armazenagem foram realizadas análises sensoriais de aceitação quanto ao sabor e aparência, utilizando escala hedônica não estruturada de 9cm e 30 provadores por sessão. Foram realizadas também análises do teor de sólidos solúveis, acidez titulável e vitamina C ao longo da armazenagem. As frutas embaladas apresentaram taxas de perda de massa 28 vezes menores que as controle, mas não foi observada diferença significativa (p>0,05) entre as diferentes embalagens. A combinação de armazenagem a 1°C com o filme PD-955 prolongou a vida de prateleira das uvas por 63 dias contra 11 a 21 dias do controle. Nas uvas embaladas, o fim da vida-de-prateleira foi determinado por deterioração microbiológica e no controle pela perda de massa, que causou o enrugamento, perda de turgidez das bagas e ressecamento dos engaços e pedicelos.

Função dos ingredientes na consistência da massa e nas características do pão de queijo

O processo de fabricação de pão de queijo envolve basicamente escaldamento do polvilho com leite, água e óleo, amassamento com ovo, adição de queijo e assamento. Este trabalho teve como objetivo estudar a função dos ingredientes na consistência da massa e nas características dos pães de queijo produzidos. As massas foram obtidas de 100% polvilho azedo (PA), 100% polvilho doce (PD), 70% polvilho azedo + 30% polvilho doce (PS) e 50% polvilho azedo + 50% polvilho doce (PC), combinados com formulações: completa, com todos os ingredientes (FC), sem leite, mas com água (SL), sem ovo (SO) e sem queijo. As massas foram desenvolvidas no Farinógrafo Brabender, o qual teve deste modo sua forma de utilização ampliada, e a evolução da consistência destas massas foi acompanhada por meio dos gráficos gerados. As massas foram moldadas e assadas e as características dos pães analisadas. Durante o escaldamento e mistura houve elevação dos valores de consistência, o ovo causou queda drástica desta consistência e o queijo provocou nova elevação, tornando a massa moldável. A consistência das massas foi mais afetada pelas formulações sendo que, as sem leite (SL) apresentaram os maiores registros; as sem queijo (SQ) as menos consistentes. As massas sem ovo (SO) apresentaram-se secas, duras, despedaçando-se quando manuseadas. Pães de queijo FC e SQ apresentaram maior volume específico e maior diâmetro. Pães de queijo SO apresentaram menor índice de expansão. O ovo e o queijo desempenharam importante papel na obtenção de massas facilmente moldáveis, originando pães de queijo com boas características estruturais.

Perfil sensorial de pão de forma integral

O pão integral oferece uma quantidade substancial de sais minerais e fibras, desejáveis por razões econômicas e nutricionais, com crescente aumento no consumo. A Análise Descritiva Quantitativa (ADQ) proporciona completa descrição de propriedades sensoriais de produtos, e o Teste de Aceitação possibilita avaliar o quanto consumidores gostam ou não desses produtos, tanto em termos específicos quanto globais. No presente estudo, foram analisadas três amostras comerciais de pão integral, denominadas "A", "B" e "C". Para a ADQ, foram selecionados 11 provadores os quais definiram 18 atributos sensoriais e os materiais de referência para o treinamento. Os resultados da ADQ foram analisados por análise de variância, testes de médias de Tukey e análise de componentes principais. A amostra "C" obteve média maior em atributos sensoriais indesejáveis, como aroma queimado da casca, fato que contribuiu para menor preferência obtida por este produto. As amostras "A" e "B" não diferiram significativamente a pd"0,05 na maioria dos atributos analisados. Na ACP, a soma de componentes principais 1 e 2 foi de 81,57%, ou seja, a variabilidade entre as amostras é quase totalmente explicada por estes dois componentes. As amostras não diferiram entre si (p<0,05) quanto à aceitação, porém diferiram quanto à intenção de compra, sendo a intenção negativa notada para o "C" e maior para o "A".

Análise: indicadores de pesquisa do XX Congresso Brasileiro de Ciência e Tecnologia de Alimentos

Em outubro de 2006, a Regional do Paraná sediou em Curitiba o XX Congresso Brasileiro de Ciência e Tecnologia de Alimentos (XX CBCTA) com o tema Alimentos e Agroindústrias Brasileiras no Contexto Internacional. O objetivo deste Congresso foi discutir o desenvolvimento científico e tecnológico e a inovação na indústria de alimentos no cenário nacional e internacional. O programa científico foi abrangente e diversificado, com Conferências, Palestras, Mesas-Redondas, Curso de Atualização, Clínicas Tecnológicas, Visitas Técnicas e Apresentações de Trabalhos Científicos em oito áreas definidas pelo Congresso. Como resultado da realização do XX CBCTA, esta análise visa uma apresentação e discussão dos indicadores da pesquisa da área de Ciência e Tecnologia de Alimentos do País e contribuição ao desenvolvimento científico e tecnológico da área, bem como subsídios para órgãos de fomento para decisão de investimentos na pesquisa e na formação de recursos humanos. No XX CBCTA, foi apresentado um total de 2066 trabalhos científicos de todo o Brasil, com exceção do Estado de Rondônia. Os trabalhos foram registrados no banco de dados e utilizados para esta análise. As inscrições foram escolhidas de acordo com a área da pesquisa de cada trabalho, sob responsabilidade de cada autor. As áreas definidas pela Comissão Científica do Congresso foram: Embalagem (EB); Método Analítico (MA); Microbiologia, Micotoxicologia e Biotecnologia (MB); Nutrição, Saúde e Alimentação (NA); Processo e Desenvolvimento de Produto (PD); Qualidade de Alimentos (QA); Química e Bioquímica (QB); e Resíduo Agroindustrial e Meio Ambiente (RM). Foi utilizado o Programa da Microsoft® Office Excel para a composição dos gráficos, versão Windows XP.

The role of metal ions in selective and sustainable processes

Sustainability and recycling are core values in today’s industrial operations. New materials, products and processes need to be designed in such a way as to consume fewer of the diminishing resources we have available and to put as little strain on the environment as possible. An integral part of this is cleaning and recycling. New processes are to be designed to improve the efficiency in this aspect. Wastewater, including municipal wastewaters, is treated in several steps including chemical and mechanical cleaning of waters. Well-cleaned water can be recycled and reused. Clean water for everyone is one of the greatest challenges we are facing today. Ferric sulphate, made by oxidation from ferrous sulphate, is used in water purification. The oxidation of ferrous sulphate, FeSO4, to ferric sulphate in acidic aqueous solutions of H2SO4 over finely dispersed active carbon particles was studied in a vigorously stirred batch reactor. Molecular oxygen was used as the oxidation agent and several catalysts were screened: active carbon, active carbon impregnated with Pt, Rh, Pd and Ru. Both active carbon and noble metal-active carbon catalysts enhanced the oxidation rate considerably. The order of the noble metals according to the effect was: Pt >> Rh > Pd, Ru. By the use of catalysts, the production capacities of existing oxidation units can be considerably increased. Good coagulants have a high charge on a long polymer chain effectively capturing dirty particles of the opposite charge. Analysis of the reaction product indicated that it is possible to obtain polymeric iron-based products with good coagulation properties. Systematic kinetic experiments were carried out at the temperature and pressure ranges of 60B100°C and 4B10 bar, respectively. The results revealed that both non-catalytic and catalytic oxidation of Fe2+ to Fe3+ take place simultaneously. The experimental data were fitted to rate equations, which were based on a plausible reaction mechanism: adsorption of dissolved oxygen on active carbon, electron transfer from Fe2+ ions to adsorbed oxygen and formation of surface hydroxyls. A comparison of the Fe2+ concentrations predicted by the kinetic model with the experimentally observed concentrations indicated that the mechanistic rate equations were able to describe the intrinsic oxidation kinetics of Fe2+ over active carbon and active carbon-noble metal catalysts. Engineering aspects were closely considered and effort was directed to utilizing existing equipment in the production of the new coagulant. Ferrous sulphate can be catalytically oxidized to produce a novel long-chained polymeric iron-based flocculent in an easy and affordable way in existing facilities. The results can be used for modelling the reactors and for scale-up. Ferric iron (Fe3+) was successfully applied for the dissolution of sphalerite. Sphalerite contains indium, gallium and germanium, among others, and the application can promote their recovery. The understanding of the reduction process of ferric to ferrous iron can be used to develop further the understanding of the dissolution mechanisms and oxidation of ferrous sulphate. Indium, gallium and germanium face an ever-increasing demand in the electronics industry, among others. The supply is, however, very limited. The fact that most part of the material is obtained through secondary production means that real production quota depends on the primary material production. This also sets the pricing. The primary production material is in most cases zinc and aluminium. Recycling of scrap material and the utilization of industrial waste, containing indium, gallium and geranium, is a necessity without real options. As a part of this study plausible methods for the recovery of indium, gallium and germanium have been studied. The results were encouraging and provided information about the precipitation of these valuables from highly acidic solutions. Indium and gallium were separated from acidic sulphuric acid solutions by precipitation with basic sulphates such as alunite or they were precipitated as basic sulphates of their own as galliunite and indiunite. Germanium may precipitate as a basic sulphate of a mixed composition. The precipitation is rapid and the selectivity is good. When the solutions contain both indium and gallium then the results show that gallium should be separated before indium to achieve a better selectivity. Germanium was separated from highly acidic sulphuric acid solutions containing other metals as well by precipitating with tannic acid. This is a highly selective method. According to the study other commonly found metals in the solution do not affect germanium precipitation. The reduction of ferric iron to ferrous, the precipitation of indium, gallium and germanium, and the dissolution of the raw materials are strongly depending on temperature and pH. The temperature and pH effect were studied and which contributed to the understanding and design of the different process steps. Increased temperature and reduced pH improve the reduction rate. Finally, the gained understanding in the studied areas can be employed to develop better industrial processes not only on a large scale but also increasingly on a smaller scale. The small amounts of indium, gallium and germanium may favour smaller and more locally bound recovery.

Alteração do teor de cálcio no banho de DP para 2,5 mEq/L é eficaz no reestabelecimento dos valores preconizados por diretrizes atuais em pacientes com PTH < 150 pg/dL

INTRODUÇÃO/OBJETIVO: A doença óssea adinâmica (DOA) é um achado comum em diálise peritoneal (PD) e é considerada fator de risco para desenvolvimento de fraturas e doença cardiovascular. Dados do BRAZPD apontam as soluções de cálcio a 3,5 mEq/L presentes na maioria das prescrições no país, que possui quase 9.000 pacientes em PD. É comum o balanço positivo de cálcio com concentrações a 3,5 mEq/L contribuindo para o desenvolvimento de DOA. Diretrizes atuais recomendam um PTHi na DRC V em diálise entre 2 e 9 vezes (150-500 pg/mL) o valor máximo da normalidade. O objetivo deste estudo foi avaliar a resposta em 6 meses do PTH-i após a conversão para solução de cálcio a 2,5 mEq/L de pacientes que usavam soluções com cálcio a 3,5 mEq/L e com PTH-i basal < 150 pg/mL. MÉTODOS: Coorte prospectiva, observacional, na qual todos pacientes prevalentes em PD entre janeiro de 2008 e janeiro de 2009 de um único centro foram incluídos. Critérios de inclusão foram:(1) estar em uso de solução de DP com cálcio a 3,5 mEq/L; (2)PTH sérico < 150 pg/mL. A critério médico, os pacientes poderiam ser convertidos ou não para soluções cálcio a 2,5 mEq/L. RESULTADOS: 35 pacientes (idade média 62 ± 17 anos) foram incluídos. Desses, 22 foram convertidos para solução de cálcio 2,5 mEq/L. Nefropatia diabética foi a principal doença de base (36%) seguido por HAS (25%) e GNC (14%). Os grupos apresentavam valores basais semelhantes de PTH, cálcio, fósforo e fosfatase alcalina. No grupo-intervenção, houve aumento significativamente maior de PTH em 6 meses comparado com o grupo-controle (Δ194 pg/dL versus Δ 92/dL; p < 0,05). Dos convertidos, 41% atingiram os valores alvo de PTH contra 14% (p < 0,05) do grupo-controle. Fósforo, cálcio e fosfatase alcalina foram semelhantes entre os grupos. CONCLUSÃO: O uso de soluções com cálcio a 2,5 mEq/L para pacientes com PTHi < 150 pg/dL comparado a soluções de cálcio 3,5 mEq/L parece uma estratégia simples e efetiva para trazer os valores de PTHi dentro da faixa atualmente sugerida nas diretrizes.

Hydrogen Sensor Application of Anodic Titanium Oxide Nanostructures

Hydrogen (H2) fuel cells have been considered a promising renewable energy source. The recent growth of H2 economy has required highly sensitive, micro-sized and cost-effective H2 sensor for monitoring concentrations and alerting to leakages due to the flammability and explosiveness of H2 Titanium dioxide (TiO2) made by electrochemical anodic oxidation has shown great potential as a H2 sensing material. The aim of this thesis is to develop highly sensitive H2 sensor using anodized TiO2. The sensor enables mass production and integration with microelectronics by preparing the oxide layer on suitable substrate. Morphology, elemental composition, crystal phase, electrical properties and H2 sensing properties of TiO2 nanostructures prepared on Ti foil, Si and SiO2/Si substrates were characterized. Initially, vertically oriented TiO2 nanotubes as the sensing material were obtained by anodizing Ti foil. The morphological properties of tubes could be tailored by varying the applied voltages of the anodization. The transparent oxide layer creates an interference color phenomena with white light illumination on the oxide surface. This coloration effect can be used to predict the morphological properties of the TiO2 nanostructures. The crystal phase transition from amorphous to anatase or rutile, or the mixture of anatase and rutile was observed with varying heat treatment temperatures. However, the H2 sensing properties of TiO2 nanotubes at room temperature were insufficient. H2 sensors using TiO2 nanostructures formed on Si and SiO2/Si substrates were demonstrated. In both cases, a Ti layer deposited on the substrates by a DC magnetron sputtering method was successfully anodized. A mesoporous TiO2 layer obtained on Si by anodization in an aqueous electrolyte at 5°C showed diode behavior, which was influenced by the work function difference of Pt metal electrodes and the oxide layer. The sensor enabled the detection of H2 (20-1000 ppm) at low operating temperatures (50–140°C) in ambient air. A Pd decorated tubular TiO2 layer was prepared on metal electrodes patterned SiO2/Si wafer by anodization in an organic electrolyte at 5°C. The sensor showed significantly enhanced H2 sensing properties, and detected hydrogen in the range of a few ppm with fast response/recovery time. The metal electrodes placed under the oxide layer also enhanced the mechanical tolerance of the sensor. The concept of TiO2 nanostructures on alternative substrates could be a prospect for microelectronic applications and mass production of gas sensors. The gas sensor properties can be further improved by modifying material morphologies and decorating it with catalytic materials.

Searching for music archives and composition manuscripts from the Viola database

Music archives and composition manuscripts from the Viola database.

Sökning i musikarkiv och notmanuskript i databasen Viola

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