939 resultados para Spherical roller bearing


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Objective. The prevalence of smoking in Aboriginal Canadians is higher than non-Aboriginal Canadians, a behavior that also tends to alter dietary patterns. Compared with the general Canadian population, maternal smoking rates are almost twice as high. The aim of this study was to compare dietary adequacy of Inuvialuit women of childbearing age comparing smokers versus non-smokers. Research methods & procedures. A cross-sectional study, where participants completed a culturally specific quantitative food frequency questionnaire. Non-parametric analysis was used to compare mean nutrient intake, dietary inadequacy and differences in nutrient density among smokers and non-smokers. Multiple logistic regression analyses were performed for key nutrients inadequacy and smoking status. Data was collected from three communities in the Beaufort Delta region of the Northwest Territories, Canada from randomly selected Inuvialuit women of childbearing age (19-44 years). Results: Of 92 participants, 75% reported being smokers. There were no significant differences in age, BMI, marital status, education, number of people in household working and/or number of self employed, and physical activity between smokers and non-smokers. Non-parametric analysis showed no differences in nutrient intake between smokers and non-smokers. Logistic regression however revealed there was a positive association between smoking and inadequacies of vitamin C (OR = 2.91, 95% CI, 1.17-5.25), iron (OR = 3.16, 95% CI, 1.27-5.90), and zinc (OR = 2.78, 95% CI, 1.12-4.94). A high percentage of women (>60%), regardless of smoking status, did not meet the dietary recommendations for fiber, vitamin D, E and potassium. Conclusions: This study provides evidence of inadequate dietary intake among Inuvialuit of childbearing age regardless of smoking behavior.

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Coccolithophores play an important role in organic matter export due to their production of the mineral calcite that can act as ballast. Recent studies indicated that calcification in coccolithophores may be affected by changes in seawater carbonate chemistry. We investigated the influence of CO2 on the aggregation and sinking behaviour of the coccolithophore Emiliania huxleyi (PML B92/11) during a laboratory experiment. The coccolithophores were grown under low (~180 µatm), medium (~380 µatm), and high (~750 µatm) CO2 conditions. Aggregation of the cells was promoted using roller tables. Size and settling velocity of aggregates were determined during the incubation using video image analysis. Our results indicate that aggregate properties are sensitive to changes in the degree of ballasting, as evoked by ocean acidification. Average sinking velocity was highest for low CO2 aggregates (~1292 m d-1) that also had the highest particulate inorganic to particulate organic carbon (PIC/POC) ratio. Lowest PIC/POC ratios and lowest sinking velocity (~366 m d-1) at comparable sizes were observed for aggregates of the high CO2 treatment. Aggregates of the high CO2 treatment showed a 4-fold lower excess density (~4.2*10**-4 g cm**-3) when compared to aggregates from the medium and low CO2 treatments (~1.7 g*10**-3 cm**-3). We also observed that more aggregates formed in the high CO2 treatment, and that those aggregates contained more bacteria than aggregates in the medium and low CO2 treatment. If applicable to the future ocean, our findings suggest that a CO2 induced reduction of the calcite content of aggregates could weaken the deep export of organic matter in the ocean, particularly in areas dominated by coccolithophores.

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A recently developed novel biomass fuel pellet, the Q’ Pellet, offers significant improvements over conventional white pellets, with characteristics comparable to those of coal. The Q’ Pellet was initially created at bench scale using a proprietary die and punch design, in which the biomass was torrefied in-situ¬ and then compressed. To bring the benefits of the Q’ Pellet to a commercial level, it must be capable of being produced in a continuous process at a competitive cost. A prototype machine was previously constructed in a first effort to assess continuous processing of the Q’ Pellet. The prototype torrefied biomass in a separate, ex-situ reactor and transported it into a rotary compression stage. Upon evaluation, parts of the prototype were found to be unsuccessful and required a redesign of the material transport method as well as the compression mechanism. A process was developed in which material was torrefied ex-situ and extruded in a pre-compression stage. The extruded biomass overcame multiple handling issues that had been experienced with un-densified biomass, facilitating efficient material transport. Biomass was extruded directly into a novel re-designed pelletizing die, which incorporated a removable cap, ejection pin and a die spring to accommodate a repeatable continuous process. Although after several uses the die required manual intervention due to minor design and manufacturing quality limitations, the system clearly demonstrated the capability of producing the Q’ Pellet in a continuous process. Q’ Pellets produced by the pre-compression method and pelletized in the re-designed die had an average dry basis gross calorific value of 22.04 MJ/kg, pellet durability index of 99.86% and dried to 6.2% of its initial mass following 24 hours submerged in water. This compares well with literature results of 21.29 MJ/kg, 100% pellet durability index and <5% mass increase in a water submersion test. These results indicate that the methods developed herein are capable of producing Q’ Pellets in a continuous process with fuel properties competitive with coal.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Denna studie har haft som syfte att undersöka hur mäns och kvinnors roller, sexualitet och ideal inom en muslimsk kontext ser ut. Detta gjordes genom en analys av tre olika böcker, vilka hade tre olika perspektiv och var producerade under tre olika tidsperioder. Böckerna var Den doftande trädgården från år 1966, vilket var det orientalistiska perspektivet, The muslim marriage guide från år 1995, vilket var det neo-traditionella perspektivet samt Sexual Ethics and Islam från år 2006, vilket var det feministiska perspektivet. För att kunna undersöka dessa böcker analyserades dem utifrån verktyg från lingvistisk och visuell textanalys samt kategoriserades och komparerades. Resultatet blev att böckerna både hade likheter och skillnader gällande mäns och kvinnors roller, sexualitet och ideal. Kvinnor framställdes genom feminina egenskaper som omsorgsfull, hemmafru, vacker och sexuell tillgänglighet, medan män framställdes genom maskulina egenskaper som ledare, styrka, ansvarsfull och sexuell skicklighet. Män kunde också oftare ses som önskvärda deltagare och utföra fler handlingar än kvinnor. I vissa delar av materialet förekom även orientalistiska framställningar.

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The objective of this study was to assess worker exposure to mineral dust particles and a metabolic model, based on the model adopted by ICRP, was applied to assess human exposure to Ta, and predicted values of Ta concentrations in excreta. The occupational exposure to Th, U, Nb, and Ta bearing particles during routine tasks to obtain Fe-Nb alloys was estimated using air samplers and excreta samples. Ta concentrations in food samples and in drinking water were also determined. The results support that workers were occupationally exposed to Ta bearing particles, and also indicate that a source of Ta exposure for both workers and the control group was the ingestion of drinking water containing soluble compounds of Ta. Therefore, some Ta compounds should be considered soluble compounds in gastrointestinal tract. Consequently the metabolic model based on ICRP metabolic model and/or the transfer factor f1 for Ta should be reviewed and the solubility of Ta compounds in gastrointestinal should be determined.

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Dans la région de Trois-Rivières (Québec, Canada), plus de 1 000 bâtiments résidentiels et commerciaux montrent de graves problèmes de détérioration du béton. Les problèmes de détérioration sont liés à l’oxydation des sulfures de fer incorporés dans le granulat utilisé pour la confection du béton. Ce projet de doctorat vise à mieux comprendre les mécanismes responsables de la détérioration de béton incorporant des granulats contenant des sulfures de fer, et ce afin de développer une méthodologie pour évaluer efficacement la réactivité potentielle de ce type de granulats. Un examen pétrographique détaillé de carottes de béton extraites de fondations résidentielles montrant différents degré d’endommagement a été réalisé. Le granulat problématique contenant des sulfures de fer a été identifié comme un gabbro à hypersthène incorporant différentes proportions (selon les différentes localisations dans les deux carrières d’origine) de pyrrhotite, pyrite, chalcopyrite et pentlandite. Les produits de réaction secondaires observés dans les échantillons dégradés comprennent des formes minérales de "rouille", gypse, ettringite et thaumasite. Ces observations ont permis de déterminer qu’en présence d’eau et d’oxygène, la pyrrhotite s’oxyde pour former des oxyhydroxides de fer et de l’acide sulfurique qui provoquent une attaque aux sulfates dans le béton. Tout d’abord, la fiabilité de l’approche chimique proposée dans la norme européenne NF EN 12 620, qui consiste à mesurer la teneur en soufre total (ST,% en masse) dans le granulat pour détecter la présence (ou non) de sulfures de fer, a été évaluée de façon critique. Environ 50% (21/43) des granulats testés, représentant une variété de types de roches/lithologies, a montré une ST > 0,10%, montrant qu’une proportion importante de types de roches ne contient pas une quantité notable de sulfure, qui, pour la plupart d’entre eux, sont susceptibles d’être inoffensifs dans le béton. Ces types de roches/granulats nécessiteraient toutefois d’autres tests pour identifier la présence potentielle de pyrrhotite compte tenu de la limite de ST de 0,10 % proposée dans les normes européennes. Basé sur une revue exhaustive de la littérature et de nombreuses analyses de laboratoire, un test accéléré d’expansion sur barres de mortier divisé en deux phases a ensuite été développé pour reproduire, en laboratoire, les mécanismes de détérioration observés à Trois-Rivières. Le test consiste en un conditionnement de 90 jours à 80°C/80% RH, avec 2 cycles de mouillage de trois heures chacun, par semaine, dans une solution d’hypochlorite de sodium (eau de javel) à 6% (Phase I), suivi d’une période pouvant atteindre 90 jours de conditionnement à 4°C/100 % HR (Phase II). Les granulats ayant un potentiel d’oxydation ont présenté une expansion de 0,10 % au cours de la Phase I, tandis que la formation potentielle de thaumasite est détectée par le regain rapide de l’expansion suivi par la destruction des échantillons durant la Phase II. Un test de consommation d’oxygène a également été modifié à partir d’un test de Drainage Minier Acide, afin d’évaluer quantitativement le potentiel d’oxydation des sulfures de fer incorporés dans les granulats à béton. Cette technique mesure le taux de consommation d’oxygène dans la partie supérieure d’un cylindre fermé contenant une couche de matériau compacté afin de déterminer son potentiel d’oxydation. Des paramètres optimisés pour évaluer le potentiel d’oxydation des granulats comprennent une taille de particule inférieure à 150 μm, saturation à 40 %, un rapport de 10 cm d’épaisseur de granulat par 10 cm de dégagement et trois heures d’essai à 22ᵒC. Les résultats obtenus montrent que le test est capable de discriminer les granulats contenant des sulfures de fer des granulats de contrôle (sans sulfures de fer) avec un seuil limite fixé à 5% d’oxygène consommé. Finalement, un protocole d’évaluation capable d’estimer les effets néfastes potentiels des granulats à béton incorporant des sulfures de fer a été proposé. Le protocole est divisé en 3 grandes phases: (1) mesure de la teneur en soufre total, (2) évaluation de la consommation d’oxygène, et (3) un test accéléré d’expansion sur barres de mortier. Des limites provisoires sont proposées pour chaque phase du protocole, qui doivent être encore validées par la mise à l’essai d’un plus large éventail de granulats.

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Background: Medial UKA performed in England and Wales represents 7 to 11% of all knee arthroplasty procedures, and is most commonly performed using mobile-bearing designs. Fixed bearing eliminates the risk of bearing dislocation, however some studies have shown higher revision rates for all-polyethylene tibial components compared to those that utilize metal-backed implants. The aim of the study is to analyse survivorship and maximum 8-year clinical outcome of medial fixed bearing, Uniglide unicompartmental knee arthroplasty performed using an all-polyethylene tibial component with a minimal invasive approach. Methods: Between 2002 and 2009, 270 medial fixed UKAs were performed in our unit. Patients were reviewed pre-operatively, 5 and 8 years post-operatively. Clinical and radiographic reviews were carried out. Patients’ outcome scores (Oxford, WOMAC and American Knee Score) were documented in our database and analysed. Results: Survival and clinical outcome data of 236 knees with a mean 7.3 years follow-up are reported. Every patient with less than 4.93 years follow-up underwent a revision. The patients’ average age at the time of surgery was 69.5 years. The American Knee Society Pain and Function scores, the Oxford Knee Score and the WOMAC score all improved significantly. The 5 years survival rate was 94.1% with implant revision surgery as an end point. The estimated 10 years survival rate is 91.3%. 14 patients were revised before the 5 year follow-up. Conclusion: Fixed bearing Uniglide UKA with an all-polyethylene tibial component is a valuable tool in the management of a medial compartment osteoarthritis, affording good short term survivorship.

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Title of dissertation: MAGNETIC AND ACOUSTIC INVESTIGATIONS OF TURBULENT SPHERICAL COUETTE FLOW Matthew M. Adams, Doctor of Philosophy, 2016 Dissertation directed by: Professor Daniel Lathrop Department of Physics This dissertation describes experiments in spherical Couette devices, using both gas and liquid sodium. The experimental geometry is motivated by the Earth's outer core, the seat of the geodynamo, and consists of an outer spherical shell and an inner sphere, both of which can be rotated independently to drive a shear flow in the fluid lying between them. In the case of experiments with liquid sodium, we apply DC axial magnetic fields, with a dominant dipole or quadrupole component, to the system. We measure the magnetic field induced by the flow of liquid sodium using an external array of Hall effect magnetic field probes, as well as two probes inserted into the fluid volume. This gives information about possible velocity patterns present, and we extend previous work categorizing flow states, noting further information that can be extracted from the induced field measurements. The limitations due to a lack of direct velocity measurements prompted us to work on developing the technique of using acoustic modes to measure zonal flows. Using gas as the working fluid in our 60~cm diameter spherical Couette experiment, we identified acoustic modes of the container, and obtained excellent agreement with theoretical predictions. For the case of uniform rotation of the system, we compared the acoustic mode frequency splittings with theoretical predictions for solid body flow, and obtained excellent agreement. This gave us confidence in extending this work to the case of differential rotation, with a turbulent flow state. Using the measured splittings for this case, our colleagues performed an inversion to infer the pattern of zonal velocities within the flow, the first such inversion in a rotating laboratory experiment. This technique holds promise for use in liquid sodium experiments, for which zonal flow measurements have historically been challenging.

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Experimental geophysical fluid dynamics often examines regimes of fluid flow infeasible for computer simulations. Velocimetry of zonal flows present in these regimes brings many challenges when the fluid is opaque and vigorously rotating; spherical Couette flows with molten metals are one such example. The fine structure of the acoustic spectrum can be related to the fluid’s velocity field, and inverse spectral methods can be used to predict and, with sufficient acoustic data, mathematically reconstruct the velocity field. The methods are to some extent inherited from helioseismology. This work develops a Finite Element Method suitable to matching the geometries of experimental setups, as well as modelling the acoustics based on that geometry and zonal flows therein. As an application, this work uses the 60-cm setup Dynamo 3.5 at the University of Maryland Nonlinear Dynamics Laboratory. Additionally, results obtained using a small acoustic data set from recent experiments in air are provided.

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Although the primary objective on designing a structure is to support the external loads, the achievement of an optimal layout that reduces all costs associated with the structure is an aspect of increasing interest. The problem of finding the optimal layout for bridgelike structures subjected to a uniform load is considered. The problem is formulated following a theory on economy of frame structures, using the stress volume as the objective function and including the selection of appropriate values for statically indeterminate reactions. It is solved in a function space of finite dimension instead of using a general variational approach, obtaining near-optimal solutions. The results obtained with this profitable strategy are very close to the best layouts known to date, with differences of less than 2% for the stress volume, but with a simpler layout that can be recognized in some real bridges. This strategy could be a guide to preliminary design of bridges subject to a wide class of costs.

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This study determined roller massager (RM) effectiveness on ankle plantar flexors’ recovery after exercise-induced muscle damage (EIMD) stimulus. Two experiments were conducted. The first experiment (n=10) examined functional [i.e., ankle plantar flexion maximal voluntary isometric contraction (MVIC) and submaximal (30% of MVIC) sustained force; ankle dorsiflexion maximal range of motion and resistance to stretch; and pain pressure threshold] and morphological [medial gastrocnemius (MG) cross sectional area, thickness, fascicle length, and fascicle angle] variables, before and immediately, 1h, 24h, 48h, and 72 after EIMD. In the second experiment (n=10), changes in MG deoxyhemoglobin concentration kinetics (velocity and amplitude) during a submaximal sustained force test were observed before and 48h after EIMD. Participants performed both experiments twice, with and without (NRM) the application of a RM (6 × 45 seconds with 20 seconds rest between sets). RM intervention did not alter plantar flexors’ strength and flexibility impairment after EIMD, as well the MG morphology and oxygenation kinetics (p>0.05). On the other hand, a strong tendency for an acute (within 1 hour) change of ipsilateral (post-effects: RM=+19%, NRM=-5%, p=0.032) and contralateral (p=0.095) MG pain pressure threshold was observed. In conclusion, the present results suggest that a roller massager has no effect on muscular performance, morphology, and oxygenation recovery after EIMD, except for muscle pain pressure threshold (i.e., a soreness). Thus, RM may have potential application in recovery for people with increased muscle soreness, if performed immediately before a physical task.

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Purpose: To evaluate the antitumor activity of doxorubicine (DOX)-loaded nanoemulsion (NE) on Ehrlich ascites carcinoma (EAC)-bearing Swiss albino mice. Methods: The mice were divided into five groups (n = 20) according to the administered drug. Groups I - V were labeled as negative control (normal), positive control of the untreated EAC bearing mice (EAC control), blank nanoemulsion (BI-NE), DOX-loaded-NE (DOX/LNE) and free DOX (DOX-Sol), respectively. Cardiotoxicity was assessed by measuring changes in body and organ weight, analyzing serum enzymes and lipids, and examining histological changes in heart tissues by light microscopy. In addition, mean survival time (MST), increase in life span (ILS) and survival (S) of the mice were determined. Results: DOX/LNE group reduced levels of serum enzymes and lowered damage to heart tissues relative to DOX-Sol group. The MST of the DOX/LNE group (80 ± 0.0 days) was significantly greater than that for DOX-Sol group (34.6 ± 8.9 days), while ILS of DOX/LNE (265.30 days) was higher than that of DOX-Sol (57.99 days) by 4.6-fold. Conclusion: Administration of DOX/LNE to EAC-bearing mice improves the efficacy of DOX and reduce its side effects on the heart.

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This paper questions the current concept of quality as used in research assessment rankings and peer review, with special reference to the link often established between impact and the way this impact is measured in the form of citation counting. Taking translation studies as a case study, we will offer a two-level approach to reveal both the macro- and micro-level biases that exist in this regard. We will first review three key aspects related to the idea of the quality of publications, namely peer review, journal indexing, and journal impact factor. We will then pinpoint some of the main macro-level problems regarding current practices and criteria as applied to translation studies, such as Thomson Reuters World of Science's journal coverage, citation patterns, and publication format. Next we will provide a micro-textual and practical perspective, focusing on citation counts and suggesting a series of corrective measures to increase comparability.

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Purpose: To develop docetaxel (DTX)- and alendronate (ALN)-loaded, chitosan (CS)-conjugated polylactide- co-glycolide (PLGA) nanoparticles (NPs) to increase therapeutic efficacy in osteosarcoma cells. Methods: Drug-loaded PLGA NPs were prepared by nanoprecipitation and chemically conjugated by the carboxylic group of PLGA to the amine-bearing CS polymer. The nanocarrier was characterized by dynamic light scattering, transmission electron microscopy, scanning electron microscopy, and differential scanning calorimetry as well as by in vitro drug release and cell culture studies. Results: NP size was within the tumour targeting range (~200 nm) with an effective positive charge (20 mV), thus increasing cellular uptake efficiency. Morphological analysis revealed clear spherical particles with uniform dispersion. The NPs exhibited identical sustained release kinetics for both DTX and ALN. CS-conjugated PLGA with dual-drug-loaded (DTX and AL) NPs showed typical time-dependent cellular uptake and also displayed superior cytotoxicity in MG-63 cells compared with blank NPs, which were safe and biocompatible. Conclusion: Combined loading of DTX and ALN in NPs increased the therapeutic efficacy of the formulation for osteosarcoma treatment, thus indicating the potential benefit of a combinatorial drug regimen using nanocarriers for effective treatment of osteosarcoma.