15 resultados para Wedge and strip anode

em Aston University Research Archive


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The spatial patterns of diffuse, primitive and classic beta/A4 deposits was studied in relation to blood vessels in 24 cortical tissues from five elderly cases of Alzheimer's disease with pronounced congophilic angiopathy (CA). Beta/A4 deposit subtypes and beta/A4 stained blood vessels were clustered in the tissue. In many instances, the clusters of beta/A4 deposits and blood vessels were regularly spaced along the cortical strip. Total beta/A4 deposits were positively correlated with blood vessels in five tissues only. Similarly, clusters of diffuse and primitive beta/A4 subtypes were each positively correlated with blood vessels in two brain regions. By contrast, clusters of classic beta/A4 deposits were positively correlated with blood vessels in 62% of the cortical tissues examined. These results suggest that in patients with significant CA, initial deposition of beta/A4 protein was unrelated to blood vessels. However, clusters of classic beta/A4 deposits appeared to be in phase with clusters of blood vessels along the cortex.

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It is well established that hydrodynamic journal bearings are responsible for self-excited vibrations and have the effect of lowering the critical speeds of rotor systems. The forces within the oil film wedge, generated by the vibrating journal, may be represented by displacement and velocity coefficient~ thus allowing the dynamical behaviour of the rotor to be analysed both for stability purposes and for anticipating the response to unbalance. However, information describing these coefficients is sparse, misleading, and very often not applicable to industrial type bearings. Results of a combined analytical and experimental investigation into the hydrodynamic oil film coefficients operating in the laminar region are therefore presented, the analysis being applied to a 120 degree partial journal bearing having a 5.0 in diameter journal and a LID ratio of 1.0. The theoretical analysis shows that for this type of popular bearing, the eight linearized coefficients do not accurately describe the behaviour of the vibrating journal based on the theory of small perturbations, due to them being masked by the presence of nonlinearity. A method is developed using the second order terms of Taylor expansion whereby design charts are provided which predict the twentyeight force coefficients for both aligned, and for varying amounts of journal misalignment. The resulting non-linear equations of motion are solved using a modified Newton-Raphson method whereby the whirl trajectories are obtained, thus providing a physical appreciation of the bearing characteristics under dynamically loaded conditions.

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The nature and kinetics of electrode reactions and processes occurring for four lightweight anode systems which have been utilised in reinforced concrete cathodic protection systems have been studied. The anodes investigated were flame sprayed zinc, conductive paint and two activated titanium meshes. The electrochemical properties of each material were investigated in rapidly stirred de-oxygenated electrolytes using anodic potentiodynamic polarisation. Conductive coating electrodes were formed on glass microscope slides, whilst mesh strands were immersed directly. Oxygen evolution occurred preferentially for both mesh anodes in saturated Ca (OH)2/CaC12 solutions but was severely inhibited in less alkaline solutions and significant current only passed in chloride solutions. The main reactions for conductive paint was based on oxygen evolution in all electrolytes, although chlorides increased the electrical activity. Self-corrosion of zinc was controlled by electrolyte composition and the experimental set-up, chlorides increasing the electrical activity. Impressed current cathodic protection was applied to 25 externally exposed concrete slabs over a period of 18 months to investigate anode degradation mechanisms at normal and high current densities. Specimen chloride content, curing and reinforcement depth were also variables. Several destructive and non-destructive methods for assessing the performance of anodes were evaluated including a site instrument for quantitative "instant-off- potential measurements. The impact of cathodic protection on the concrete substrate was determined for a number of specimens using appropriate methods. Anodic degradation rates were primarily influenced by current density, followed by cemendtious alkalinity, chloride levels and by current distribution. Degradation of cementitious overlays and conductive paint substrates proceeded by sequential neutralisation of cement phases, with some evidence of paint binder oxidation. Sprayed zinc progressively formed an insulating layer of hydroxide complexes, which underwent pitting_ attack in the presence of sufficient chlorides, whilst substrate degradation was minimal. Adhesion of all anode systems decreased with increasing current density. The influence of anode material on the ionic gradients which can develop during cathodic protection was investigated. A constant current was passed through saturated cement paste prisms containing calcium chloride to central cathodes via anodes applied or embedded at each end. Pore solution was obtained from successive cut paste slices for anion and cation analyses. Various experimental errors reduced the value of the results. Characteristic S-shaped profiles were not observed and chloride ion profiles were ambiguous. Mesh anode specimens were significantly more durable than the conductive coatings in the high humidity environment. Limited results suggested zinc ion migration to the cathode region. Electrical data from each investigation clearly indicated a decreasing order of anode efficiency by specific anode material.

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The thesis presents an account of an attempt to utilize expert systems within the domain of production planning and control. The use of expert systems was proposed due to the problematical nature of a particular function within British Steel Strip Products' Operations Department: the function of Order Allocation, allocating customer orders to a production week and site. Approaches to tackling problems within production planning and control are reviewed, as are the general capabilities of expert systems. The conclusions drawn are that the domain of production planning and control contains both `soft' and `hard' problems, and that while expert systems appear to be a useful technology for this domain, this usefulness has by no means yet been demonstrated. Also, it is argued that the main stream methodology for developing expert systems is unsuited for the domain. A problem-driven approach is developed and used to tackle the Order Allocation function. The resulting system, UAAMS, contained two expert components. One of these, the scheduling procedure was not fully implemented due to inadequate software. The second expert component, the product routing procedure, was untroubled by such difficulties, though it was unusable on its own; thus a second system was developed. This system, MICRO-X10, duplicated the function of X10, a complex database query routine used daily by Order Allocation. A prototype version of MICRO-X10 proved too slow to be useful but allowed implementation and maintenance issues to be analysed. In conclusion, the usefulness of the problem-driven approach to expert systems development within production planning and control is demonstrated but restrictions imposed by current expert system software are highlighted in that the abilities of such software to cope with `hard' scheduling constructs and also the slow processing speeds of such software can restrict the current usefulness of expert systems within production planning and control.

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Infection is a major clinical problem associated with the use of intravenous catheters.The efficacy of a direct electric current (10µA, 9V) via electrode-conducting carbon impregnated catheters to prevent colonisation of catheters by micro-organisms was investigated. The range of organisms susceptible to 10µA was determined by a zone of inhibition test. The catheters acting as the anode and the cathode were inserted into a nutrient agar plate inoculated with a lawn of bacteria. There was no zone of inhibition observed around the anode. Organisms susceptible to 10µA at the cathode were Staphylococcus aureus (2 strains), Staphylococcus epidermidis (5 strains), Escherichia coli and Klebsiella pneumoniae (2 strains each), and one strain of the following micro-organisms: Staphylococcus hominis, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans. The zones ranged from 6 to 16 mm in diameter according to the organisms under test. The zone size was proportional to the amperage (10 - 100 µA) and the number of organisms on the plate. Ten µA did not prevent adhesion of staphylococci to the cathode nor did it affect their growth in nutrient broth. However, it was bactericidal to adherent bacteria on the cathodal catheter and significantly reduced the number of bacteria on the catheter after 4 to 24 h application of electricity. The antimicrobial activity of low amperage electric current under anaerobic conditions and in the absence of chloride ions against bacteria attached to the surface of a current carrying electrode was also investigated.The mechanisms of the bactericidal activity associated with the cathode were investigated with S. epidermidis and S. aureus. The inhibition zone was greatly reduced in the presence of catalase. There was no zone around the cathode when the test was carried out under anaerobic conditions. Hydrogen peroxide was produced at the cathode surface under aerobic conditions, but not in the absence of oxygen. A salt-bridge apparatus was used to demonstrate further that hydrogen peroxide was produced at the cathode, and chlorine at the anode. The antimicrobial activity of low amperage electric current under anaerobic conditions and in the absence of chloride ions against bacteria attached to the surface of a current carrying electrode was also investigated. Antibacterial activity was reduced under anaerobic conditions, which is compatible with the role of hydrogen peroxide as a primary bactericidal agent of electricity associated with the cathode. A reduction in chloride ions did not significantly reduce the antibacterial activity suggesting chlorine plays only a minor role in the bactericidal activity against organisms attached to anodal electrode surfaces. The bactericidal activity of electric current associated with the cathode and H202 was greatly reduced in the presence of 50 μM to 0.5 mM magnesium ions in the test menstrum. Ten μA applied via the catheters did not prevent the initial biofilm growth by the adherent bacteria but reduced the number of bacteria in the biofilm by 2 log order aiter 24 h. The results suggested that 10 μA may prevent the colonisation of catheters by both the extra~ and intra-luminal routes. The localised production of hydrogen peroxide and chlorine and the intrinsic activity due to electric current may offer a useful method for the eradication of bacteria from catheter surfaces.

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In Alzheimer's disease (AD), the 'Cascade hypothesis' proposes that the formation of paired helical filaments (PHF) may be casually linked to the deposition of beta/A4 protein. Hence, there should be a close spatial relationship between senile plaques and cellular neurofibrillary tangles in a local region of the brain. In tissue from 6 AD patients, plaques and tangles occurred in clusters and individual clusters were often regularly spaced along the cortical strip. However, the clusters of plaques and tangles were in phase in only 4/32 cortical tissues examined. Hence, the data were not consistent with the 'Cascade hypothesis' that beta/A4 and PHF are directly linked in AD.

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This paper studies the payout policy of Italian firms controlled by large majority shareholders (controlled firms). The paper reports that a firm’s share of dividends in total payout (dividends plus repurchases) is negatively related to the size of the cash flow stake of the firm’s controlling shareholder and positively associated with the wedge between the controlling shareholder’s control rights and cash flow rights. These findings are consistent with the substitute model of payout. One of the implications of this model is that controlled firms with weak corporate governance set-ups, in which controlling shareholders have strong incentives to expropriate minority shareholders, tend to prefer dividends over repurchases when disgorging cash.

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The rise of male strip shows marketed towards heterosexual women has called into question the idea that only men can 'gaze' or be 'sexual scrutinizers' in public leisure spaces. This paper details the findings of an ethnographic study of a male strip event 'Cheeky's',1 located in the Midlands, England. Utilising observation, informal interviews and photography, the paper describes the physical environment and the atmosphere of the event, and analyses interview data with female customers. The paper questions what spaces such as Cheeky's mean for female sexualities, sexual roles and desires. The findings are twofold. On the one hand the club was a relatively novel sexual space, as some women spectators experienced it as an 'empowering' space in which they could be 'sexually aggressive'; on the other hand, the character of the club was actively and adeptly manufactured by the Master of Ceremonies (MC), and male dancers, so as to encourage - and even to coercively elicit - extrovert behaviour from women customers. Despite shifting normative gendered expectations of women's sexual behaviour to some extent, ultimately the club structured women's sexual experiences around traditional heterosexist lines. The club did not encourage women's autonomous sexual expression, and many women claimed they had not found it a very 'sexy space'. © 2011 Taylor & Francis.

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This paper seeks to characterise the gendered and sexualised power relations of both female and male strip clubs, and to signal what this means for establishing positive definitions of female desire. It is argued that while it is not useful to present female strippers, or female patrons of male strip clubs as purely passive victims of male heterosexism within these venues, it is equally damaging to assume that these venues represent a whole-scale challenge to conventional oppressive gender and sexual relations for women. Some research has even suggested that both strippers and their patrons are engaged in a 'mutually exploitative' power relationship. Moreover, further empirical research documents key points where female dancers have perhaps wielded 'more' power over patrons at certain moments, and female dancers have highlighted feelings of empowerment and highlighted potential for gender and sexual relations which position women as passive to be subverted within stripping. However, such feelings are often temporally specific and are not applicable to all women in the strip industry. It may be particularly hard for these to manifest in women concentrated in the least economically-rewarding areas of the industry who have less 'power' to resist compromising their bodily boundaries. Furthermore, it is argued that women watching male strippers does little to reverse the 'male gaze', and nor does this male occupation carry as much negative social stigma with it as female stripping suffers. It is thus argued that the overwhelming picture, stemming largely from accounts of former dancers and from empirical studies of individual clubs, suggests these venues in fact do very little to challenge normative hetero-oppressive sexual scripts.

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Aim: To evaluate OneTouch® Verio™ test strip performance at hypoglycaemic blood glucose (BG) levels (<3.9mmol/L [<70mg/dL]) at seven clinical studies. Methods: Trained clinical staff performed duplicate capillary BG monitoring system tests on 700 individuals with type 1 and type 2 diabetes using blood from a single fingerstick lancing. BG reference values were obtained using a YSI 2300 STAT™ Glucose Analyzer. The number and percentage of BG values within ±0.83. mmol/L (±15. mg/dL) and ±0.56. mmol/L (±10. mg/dL) were calculated at BG concentrations of <3.9. mmol/L (<70. mg/dL), <3.3. mmol/L (<60. mg/dL), and <2.8. mmol/L (<50. mg/dL). Results: At BG concentrations <3.9. mmol/L (<70. mg/dL), 674/674 (100%) of meter results were within ±0.83. mmol/L (±15. mg/dL) and 666/674 (98.8%) were within ±0.56. mmol/L (±10. mg/dL) of reference values. At BG concentrations <3.3. mmol/L (<60. mg/dL), and <2.8. mmol/L (<50. mg/dL), 358/358 (100%) and 270/270 (100%) were within ±0.56. mmol/L (±10. mg/dL) of reference values, respectively. Conclusion: In this analysis of data from seven independent studies, OneTouch Verio test strips provide highly accurate results at hypoglycaemic BG levels. © 2012 Elsevier Ireland Ltd.

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The self-assembly of cobalt coordination frameworks (Co-CPs) with a two-dimensional morphology is demonstrated by a solvothermal method. The morphology of the Co-CPs has been controlled by various solvothermal conditions. The two-dimensional nanostructures agglomerated by Co3O4 nanoparticles remained after the pyrolysis of the Co-CPs. The as-synthesized Co3O4 anode material is characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge measurements. The morphology of Co3O4 plays a crucial role in the high performance anode materials for lithium batteries. The Co3O4 nanoparticles with opened-book morphology deliver a high capacity of 597 mA h g-1 after 50 cycles at a current rate of 800 mA g-1. The opened-book morphology of Co3O4 provides efficient lithium ion diffusion tunnels and increases the electrolyte/Co3O4 contact/interfacial area. At a relatively high current rate of 1200 mA g-1, Co3O4 with opened-book morphology delivers an excellent rate capability of 574 mA h g-1.

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Porous tin films as anode for lithium-ion batteries are electrodeposited on graphite paper. Homogeneous tin films with significant void space accommodate the volume change during tin lithiation/delithiation. Through adjusting the electrodeposition currents and time, the morphologies and void space of tin films on graphite paper are controllable. At fixed electrodeposition current densities, the prolonged electrodeposition time plays the role in growing big tin particles and resulting the disappearance of void space among tin particles. The increased electrodeposition current plays the role to increase the quantity of tin seeds in thickness of tin film, and the void space among tin particles remains but the thick film limits its electrochemical performance. The tin films electrodeposited at an optimized current densities and for an optimized electrodeposition time, present the best electrochemical performance, because the tin nanoparticles are well dispersed on graphite substrate including void space. The tin film electrodeposited at 0.2 A cm-2 for 2 min shows the capacity of 1.0 mAh cm-2 after 50 charge/discharge cycles. The void space of tin film is very important for the best capacity and cyclic ability. The metallic tin film produced at 0.4 A cm-2 for 3 min remains the uniform and microporous structure after charge/discharge for 50 cycles.

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G-protein-coupled receptors (GPCRs) form the largest class of membrane proteins and are an important target for therapeutic drugs. These receptors are highly dynamic proteins sampling a range of conformational states in order to fulfil their complex signalling roles. In order to fully understand GPCR signalling mechanisms it is necessary to extract the receptor protein out of the plasma membrane. Historically this has universally required detergents which inadvertently strip away the annulus of lipid in close association with the receptor and disrupt lateral pressure exerted by the bilayer. Detergent-solubilized GPCRs are very unstable which presents a serious hurdle to characterization by biophysical methods. A range of strategies have been developed to ameliorate the detrimental effect of removing the receptor from the membrane including amphipols and reconstitution into nanodics stabilized by membrane scaffolding proteins (MSPs) but they all require exposure to detergent. Poly(styrene-co-maleic acid) (SMA) incorporates into membranes and spontaneously forms nanoscale poly(styrene-co-maleic acid) lipid particles (SMALPs), effectively acting like a 'molecular pastry cutter' to 'solubilize' GPCRs in the complete absence of detergent at any stage and with preservation of the native annular lipid throughout the process. GPCR-SMALPs have similar pharmacological properties to membrane-bound receptor, exhibit enhanced stability compared with detergent-solubilized receptors and being non-proteinaceous in nature, are fully compatible with downstream biophysical analysis of the encapsulated GPCR.