12 research outputs found
Development of Smart Squeeze Film Dampers for Small Rotors
No full textAbstractSqueeze film dampers (SFD) are lubrication elements which provide viscous damping in rotating systems. Squeeze film dampers in rotating machinery provide structural isolation, reduce the amplitudes of rotor response to unbalance and also assist to suppress rotor dynamic instability. They have been long used to subdue instability and vibration issues that are difficult to solve using conventional bearings like journal or ball bearings. Numerous studies have been tried to produce mechanically tunable dampers which allow the damping to be changed during different mode of operation. Magneto-rheological (MR) fluids are one of the strong contenders for tunable dampers. They provide the possibility to control the dynamic characteristics of conventional fluid dampers. Magneto-rheological fluids are viscous fluids suspended with micron sized ferromagnetic particles which on application of magnetic field undergo changes in their physical and mechanical properties like viscosity, stiffness, etc. This characteristic can be used to build squeeze film damper whose damping properties will change based on the input force. In present work a typical SFD is designed and development using MR fluid and tested for different amount of damping. It is observed that the damping provided by MR fluid increases with increase in magnetic field and the amplitude of vibration reduces by 70% at critical speeds
Identification of Rays through DNA Barcoding: An Application for Ecologists
No full textDNA barcoding potentially offers scientists who are not expert taxonomists a powerful tool to support the accuracy of field studies involving taxa that are diverse and difficult to identify. The taxonomy of rays has received reasonable attention in Australia, although the fauna in remote locations such as Ningaloo Reef, Western Australia is poorly studied and the identification of some species in the field is problematic. Here, we report an application of DNA-barcoding to the identification of 16 species (from 10 genera) of tropical rays as part of an ecological study. Analysis of the dataset combined across all samples grouped sequences into clearly defined operational taxonomic units, with two conspicuous exceptions: the Neotrygon kuhlii species complex and the Aetobatus species complex. In the field, the group that presented the most difficulties for identification was the spotted whiptail rays, referred to as the 'uarnak' complex. Two sets of problems limited the successful application of DNA barcoding: (1) the presence of cryptic species, species complexes with unresolved taxonomic status and intra-specific geographical variation, and (2) insufficient numbers of entries in online databases that have been verified taxonomically, and the presence of lodged sequences in databases with inconsistent names. Nevertheless, we demonstrate the potential of the DNA barcoding approach to confirm field identifications and to highlight species complexes where taxonomic uncertainty might confound ecological data
MRR and TWR evaluation on electrical discharge machining of Ti-6Al-4V using tungsten : copper composite electrode
No full textEstudo da atividade antitumoral do extrato bruto e frações de Casearia sylvestris
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Bioquímica, Florianópolis, 2010O desenvolvimento de novas alternativas terapêuticas, como as terapias que utilizam as plantas medicinais, tem despertado grande interesse no tratamento do câncer, pois as terapias disponíveis não são capazes de regredir totalmente a evolução da patologia e/ou apresentam elevada toxicidade. A C. sylvestris, planta medicinal que possui vários usos populares no Brasil e outros paises americanos, tem sido indicada para o tratamento de tumores. Nesse contexto, o presente trabalho propôs avaliar as atividades citotóxica, antiproliferativa, pró-apoptótica, antiangiogênica e antitumoral do extrato bruto (EB-ETOH), e das frações metanólica (f-MeOH), acetato de etila (f-AcOEt) e clorofórmica (f-CHCl3) de Casearia sylvestris utilizando modelos experimentais in vitro e in vivo. Nos ensaios do MTT e incorporação de timidina triciada realizados respectivamente, para investigar a citotoxicidade e influência dos extratos sobre a proliferação celular, os resultados demonstraram que EB-ETOH, f-CHCl3 e f-AcOEt reduziram de maneira significativa a viabilidade e proliferação de células do carcinoma de Ehrlich, sendo a citotoxicidade promovida pelo tratamento com esses extratos, tempo e concentração dependente. Diante do efeito citotóxico promovido por EB-ETOH, f-CHCl3 e f-AcOEt sobre células do carcinoma de Ehrlich, avaliou-se o tipo de morte celular promovida pelos tratamentos. A coloração com brometo de etídeo/laranja de acridina (BE/LA) revelou que o provável tipo de morte celular induzida pelos tratamentos trata-se de apoptose, uma vez que a grande maioria das células, após terem entrado em contato com a referida solução corante, adquiriram uma coloração laranja-avermelhada, característica da ocorrência do fenômeno apoptótico. Entretanto, em relação à avaliação da atividade nucleásica, verificada através da realização do teste de dano ao DNA plasmidial, observou-se que os efeitos antiproliferativo e citotóxico induzidos por EB-ETOH, f-CHCl3 e f-AcOEt, não são mediados por uma interação e dano direto ao DNA. Além disso, a realização desse ensaio permitiu observar que os extratos têm a capacidade de proteger o DNA do ataque induzido por EROs, excluindo-se portanto, a possibilidade de estarem exercendo seus efeitos citotóxico e antiproliferativo através da indução de estresse oxidativo no núcleo. As avaliações morfológicas e bioquímicas realizadas nas amostras obtidas de camundongos portadores do tumor ascítico de Ehrlich mostraram que os animais tratados com EB-ETOH e f-CHCl3 apresentaram menor ganho de peso corporal (26 e 31%, respectivamente) e de circunferência abdominal (52 e 58%, respectivamente), menor volume de líquido ascítico (46 e 43%, respectivamente), aumento do percentual de longevidade (48 e 40%, respectivamente) e da proporção de células inviáveis/viáveis (70 e 78%, respectivamente), quando comparados ao grupo controle negativo. Com a realização do modelo in vivo do TAE, observou-se ainda que o efeito antitumoral promovido por esses extratos é dose-dependente, uma vez que se apresentou-maior, quanto mais elevada a concentração de extrato administrada ao animal. A realização do ensaio do CAM, permitiu verificar que tanto o EB-ETOH, como f-CHCl3 de C. sylvetris, exercem um significativo efeito antiangiogênico, de maneira dose-dependente, onde a administração de 3,25; 7,5 e 15 µg/disco de EB-ETOH e f-CHCl3 foram capazes de diminuir o percentual de vasos, em torno de 54,5; 61,4 e 71% e 42,1; 59,1 e 70,9%, respectivamente. Por fim, cabe ressaltar que a realização da biometria dos embriões possibilitou observar que o tratamento dos mesmos com extrato bruto e fração clorofórmica não se apresentou tóxico, uma vez que não alterou o desenvolvimento embrionário nem a morfogênese externa, avaliados pelo comprimento total do embrião, razão comprimento cefálico/comprimento truncal e razão comprimento cefálico/comprimento total. Dessa forma, conclui-se que EB-ETOH e f-CHCl3 de C. sylvestris apresentaram efeito citotóxico, antiproliferativo, pró apoptótico e antitumoral in vitro e in vivo, sobre as células do carcinoma de Ehrlich. Tal efeito antitumoral mediado por esses extratos, não envolvem sua intercalação ao DNA, e sugere-se que se deva, pelo menos em parte, à inibição da formação de vasos e a conseqüente supressão nutricional das células tumorais
(E)-1-(2,5-Dichloro-3-thienyl)-3-(3,4-dimethoxyphenyl)prop-2-en-1-one
No full textIn the title compound, C15H12Cl2O3S, the prop-2-en-1-one (enone) fragment is almost planar [C—C—C—O = 2.2 (4)°] and it subtends dihedral angles of 11.9 (2) and 11.0 (2)° with the thiophene and benzene rings, respectively. The dihedral angle between the aromatic rings is 3.47 (16)°. In the crystal, weak C—H...O and C—H...Cl interactions link the molecules, leading to R22(14), R22(24) and C(11) supramolecular motifs occurring within the three-dimensional network. Weak aromatic π–π stacking [centroid–centroid separations = 3.6823 (15) and 3.8722 (15) Å] may also help to consolidate the packing
From user behaviours to collective semantics
No full textThe World Wide Web has developed into an important platform for social interactions with the rise of social networking applications of different kinds. Collaborative tagging systems, as prominent examples of these applications, allow users to share their resources and to interact with each other. By assigning tags to resources on the Web in a collaborative manner, users contribute to the emergence of complex networks now commonly known as folksonomies, in which users, documents and tags are interconnected with each other. To reveal the implicit semantics of entities involved in a folksonomy, one requires an understanding of the characteristics of the collective behaviours that create these interconnections. This thesis studies how user behaviours in collaborative tagging systems can be analysed to acquire a better understanding of the collective semantics of entities in folksonomies. We approach this problem from three different but closely related perspectives. Firstly, we study how tags are used by users and how their different intended meanings can be identified. Secondly, we develop a method for assessing the expertise of users and quality of documents in folksonomies by introducing the notion of implicit endorsement. Finally, we study the relations between documents induced from collaborative tagging and compare them with existing hyperlinks between Web documents. We show that, in each of these scenarios, it is crucial to consider the collective behaviours of the users and the social contexts in order to understand the characteristics of the entities. This project can be considered as a case study of the Social Web, the research outcomes of which can be easily generalised to many other social networking applications. It also fits into the larger framework for understanding the Web set out by the emerging interdisciplinary field of Web Science, as the work involves analyses of the interactions and behaviour of Web users in order to understand how we can improve existing systems and facilitate information sharing and retrieval on the Web
The effect of in vitro culture on the stability, expansion and neuronal differentiation of human pluripotent cell lines
No full textPluripotent cells are defined by their ability to both self-renew and to differentiation into any cell type within the human body. As such, pluripotent cell lines are of great interest as starting material for drug screening and cell therapies for regenerative treatment of diseased tissues. Pluripotent cell lines were originally derived from germ cell tumors (embryonal carcinoma cells; EC), but have since been isolated and expanded from the inner cell mass of an early embryo (human embryonic stem cells; hESCs).
This project set out to investigate the relative ability of the pluripotent NTERA2 (EC) cell line and hESC lines: Shef3, HUES7 and RH5, to differentiate into neurons, using mechanical and enzymatic culture methods. Focus was placed on monitoring differentiation efficiency and function between the different lines.
The tumour origin, in addition to the poor reproducibility, low yield and reduced functionality of NTERA2 derived neurons, compared to primary neurons, makes their incorporation into regenerative therapies unlikely. As such, an enhanced neuronal differentiation protocol was developed for use in hESCs. Cell populations were monitored for relative changes in gene and protein expression at selected time points throughout differentiation using standard RT-PCR, Q-PCR and immuno fluorescence analysis. End stage neurons were screened for functionality using patch clamping and calcium imaging techniques. Monitoring of cellular behavior through differentiation was aided by the concurrent development of a portable microscope incubator stage in collaboration with Linkam scientific Ltd.
These data demonstrate a variation in the ability to generate neurons from pluripotent cell lines, and suggests a predetermined, preferential cell fate within each line, even at the level of pluripotency. This study also characterises in detail neuronal differentiation from pluripotent cells, adding to the understanding which is essential for translation into therapies for neurodegenerative diseases such as Parkinson’s, Alzheimer’s, and Huntingdon’s disease
Modulation of immune responses by targeting CD169/Siglec-1 with the glycan ligand
No full textCell surface mucins configure the cell surface by presenting extended protein backbones that are heavily O-glycosylated. The glycopeptide structures establish physicochemical properties at the cell surface that enable and block the formation of biologically important molecular complexes. Some mucins, such as MUC1, associate with receptor tyrosine kinases and other cell surface receptors, and engage in signal transduction in order to communicate information regarding conditions at the cell surface to the nucleus. In that context, the MUC1 cytoplasmic tail (MUC1CT) receives phosphorylation signals from receptor tyrosine kinases and serine/threonine kinases, which enables its association with different signaling complexes that conduct these signals to the nucleus and perhaps other subcellular organelles. We have detected the MUC1CT at promoters of over 500 genes, in association with several different transcription factors, and have shown that promoter occupancy can vary under different growth factor conditions. However, the full biochemical nature of the nuclear forms of MUC1 and its function at these promoter regions remain undefined. I will present evidence that nuclear forms of the MUC1CT include extracellular and cytoplasmic tail domains. In addition, I will discuss evidence for a hypothesis that the MUC1CT possesses a novel catalytic function that enables remodeling of the transcription factor occupancy of promoters, and thereby engages in regulation of gene expression
Revisión taxonómica del género Lepidocyrtus s.l. Bourlet, 1839 (Collembola: Entomobryomorpha: Entomobryidae) para la región neotropical e inclusión de ontologías en descripciones morfológicas
No full textilustraciones, fotografías, graficas, tablasLepidocyrtus with almost 265 species described, is the largest genus of Entomobryidae, defined by 8+8 eyes, rounded scales, and bidentate mucro. The genus is taxonomically problematic because of the lack of taxonomic characters to discriminate species, or available to subgenus level. This obeys to incomplete morphological descriptions, and taxonomy based mainly on European or Asian species, which difficult, in this case, the taxonomic study of the Neotropical species. Morphological descriptions are not free of problems, related mainly to the lack of standardized anatomical terminology, required in the formalization and standardization of morphological descriptions. Due to the above, this study addresses two main objectives: 1) to review the taxonomy of the Neotropical species of the genus Lepidocyrtus, which includes the extension of previous descriptions, and description of new species. As well as the definition of groups of species and taxonomic location within subgenera; 2) to incorporate semantic methods for morphological descriptions, which includes the presentation of an anatomical ontology for Collembola (Collembola Anatomy Ontology, CLAO) and the evaluation of semantic methods based on RDF (Resource Description Framework).The examined species come from biological collections or field work, whose morphological descriptions expressed in natural language and RDF triples. In total, 52 species were examined with definition of 17 species groups based chaetotaxy, vestiture, dental tubercle, and apical bulb., As a result of the review, nineteen new species are also. Likewise, the examined species were located within the subgenera Lanocyrtus, Fractocyrtus, Ascocyrtus, Lepidocyrtus s.str., and Acrocyrtus. An Collembola Anatomy Ontology (CLAO) was developed together with the implementation of semantic methods for the morphological description of the Neotropical species of Lepidocyrtus. The morphology of Lepidocyrtus shows little variation; however, the chaetotaxy is still the main source of taxonomic characters. The proposal of groups of species contributes to the organization of the genus, but at the subgenus level a phylogenetic exploration can contribute to the delimitation of these. The anatomical ontology is a promising tool in morphological data management, which needs development in the future.Lepidocyrtus con cerca de 265 especies descritas es el género más grande de Entomobryidae, el cual es definido por el número de ocelos 8+8, escamas redondeadas, y mucrón bidentado. El género es taxonómicamente problemático debido a la carencia de caracteres taxonómicos para la delimitación de especies, o en la designación dentro de subgéneros. Lo anterior obedece a descripciones morfológicas incompletas, y taxonomía basada únicamente en especies europeas o asiáticas, lo cual dificulta, en este caso, el estudio taxonómico de las especies Neotropicales. Las descripciones morfológicas tampoco son libres de problemas, los cuales están relacionados a la falta de una terminología anatómica estandarizada requerida en la formalización y estandarización de descripciones morfológicas. Debido a lo anterior, este estudio aborda dos objetivos principales: 1) Revisar la taxonomía de las especies Neotropicales del género Lepidocyrtus, lo cual incluye la extensión de descripciones previas, y descripción de nuevas especies. Así como la definición de grupos de especies y ubicación taxonómica dentro de subgéneros; 2) Incorporar métodos semánticos para descripciones morfológicas, lo cual incluye la presentación de una ontología anatómica para Collembola (Collembola Anatomy Ontology, CLAO) y la evaluación de métodos semánticos basados sobre RDF (Resource Description Framework). Las especies examinadas proviene de colecciones biológicas o trabajo de campo, cuyas descripciones morfológicas fueron expresadas en lenguaje natural y tripletes RDF. En total, 52 especies fueron revisadas con la definición de 17 grupos de especies basados sobre la quetotaxia, vestidura, tubérculo dental, y bulbo apical. Como resultado de la revisión se proponen también 19 nuevas especies. Así mismo, las especies examinadas fueron ubicadas en los subgéneros Lanocyrtus, Fractocyrtus, Ascocyrtus, Lepidocyrtus s.str., y Acrocyrtus. Una ontología anatómica para Collembola (CLAO) fue desarrollada junto a la implementación de métodos semánticos para la descripción morfológica de las especies neotropicales de Lepidocyrtus. La morfología de Lepidocyrtus muestra poca variación; sin embargo, la quetotaxia sigue siendo la principal fuente de caracteres taxonómicos. La propuesta de grupos de especies contribuye a la organización del género, pero a nivel de subgénero una exploración filogenética puede contribuir a la delimitación de estos. Las ontologías anatómicas son una herramienta prometedora en la gestión de datos morfológicos, lo cual necesita mayor desarrollo hacia el futuro. (Texto tomado de la fuente)Minciencias, Doctorados Nacionales 727DoctoradoDoctor en Ciencias AgrariasEntomologí
Manifestaciones mucocutáneas atípicas por fiebre por el virus del chikungunya en neonatos y lactantes de Cúcuta, Los Patios y Villa del Rosario, Norte de Santander, Colombia, 2014
No full textIntroducción. Se han observado manifestaciones clínicas atípicas en recién nacidos y lactantes con fiebre por el virus del chikungunya. Objetivo. Describir los casos de fiebre causada por el virus del chikungunya en recién nacidos y lactantes con lesiones mucocutáneas atípicas. Materiales y métodos. Se revisaron las historias clínicas y los resultados de laboratorio y de patología en tres hospitales regionales de los casos de recién nacidos y lactantes diagnosticados con el virus del chikungunya que presentaban lesiones mucocutáneas atípicas; se hizo una búsqueda activa comunitaria en los barrios de residencia de los pacientes. Resultados. De 18 casos sospechosos de chikungunya en recién nacidos y lactantes, 11 pacientes con diagnóstico confirmado presentaron manifestaciones mucocutáneas atípicas. Seis de los 11 casos confirmados eran niños menores de cinco meses de edad. Los síntomas más frecuentes fueron: fiebre, eritema, irritabilidad y diarrea. Tres de los pacientes estaban infectados con dengue y chikungunya. Las úlceras se presentaron en cuero cabelludo, abdomen, región genital y perianal. En la búsqueda activa comunitaria se encontraron altas tasas de ataque de la enfermedad. Conclusiones. Se presenta un informe de las manifestaciones mucocutáneas en recién nacidos y lactantes diagnosticados con fiebre por el virus del chikungunya en Colombia. El rápido desarrollo de las úlceras se debe, probablemente, a la reacción inmunitaria al virus. Es necesario priorizar la atención de las mujeres embarazadas que presenten síntomas una semana antes del parto y hacerle seguimiento a los recién nacidos, para hacer el diagnóstico temprano del chikungunya y evitar complicaciones
