Simulating the fast transport of water through carbon nanotubes

Non-equilibrium molecular dynamics simulations are performed to investigate water transport through (7,7) CNTs and to examine how changing the CNT length affects the flow dynamics. We show that fluid flow rates are well in advance of continuum expectations and that this flow enhancement increases with increasing CNT length. This enhancement is related to the internal fluid structure. Water molecules form a tightly packed cylindrical shell inside (7,7) CNTs, with densities nearly 3.5 times that of the water reservoir

Water transport through (7,7) carbon nanotubes of different lengths using molecular dynamics

Non-equilibrium molecular dynamics simulations are used to investigate water transport through (7,7) CNTs, examining how changing the CNT length affects the internal flow dynamics. Pressure-driven water flow through CNT lengths ranging from 2.5 to 50 nm is simulated. We show that under the same applied pressure difference an increase in CNT length has a negligible effect on the resulting mass flow rate and fluid flow velocity. Flow enhancements over hydrodynamic expectations are directly proportional to the CNT length. Axial profiles of fluid properties demonstrate that entrance and exit effects are significant in the transport of water along CNTs. Large viscous losses in these entrance/exit regions lead into central “developed” regions in longer CNTs where the flow is effectively frictionless

Withdrawing performance indicators: retrospective analysis of general practice performance under UK Quality and Outcomes Framework.

This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.OBJECTIVES: To investigate the effect of withdrawing incentives on recorded quality of care, in the context of the UK Quality and Outcomes Framework pay for performance scheme. DESIGN: Retrospective longitudinal study. SETTING: Data for 644 general practices, from 2004/05 to 2011/12, extracted from the Clinical Practice Research Datalink. PARTICIPANTS: All patients registered with any of the practices over the study period-13,772,992 in total. INTERVENTION: Removal of financial incentives for aspects of care for patients with asthma, coronary heart disease, diabetes, stroke, and psychosis. MAIN OUTCOME MEASURES: Performance on eight clinical quality indicators withdrawn from a national incentive scheme: influenza immunisation (asthma) and lithium treatment monitoring (psychosis), removed in April 2006; blood pressure monitoring (coronary heart disease, diabetes, stroke), cholesterol concentration monitoring (coronary heart disease, diabetes), and blood glucose monitoring (diabetes), removed in April 2011. Multilevel mixed effects multiple linear regression models were used to quantify the effect of incentive withdrawal. RESULTS: Mean levels of performance were generally stable after the removal of the incentives, in both the short and long term. For the two indicators removed in April 2006, levels in 2011/12 were very close to 2005/06 levels, although a small but statistically significant drop was estimated for influenza immunisation. For five of the six indicators withdrawn from April 2011, no significant effect on performance was seen following removal and differences between predicted and observed scores were small. Performance on related outcome indicators retained in the scheme (such as blood pressure control) was generally unaffected. CONCLUSIONS: Following the removal of incentives, levels of performance across a range of clinical activities generally remained stable. This indicates that health benefits from incentive schemes can potentially be increased by periodically replacing existing indicators with new indicators relating to alternative aspects of care. However, all aspects of care investigated remained indirectly or partly incentivised in other indicators, and further work is needed to assess the generalisability of the findings when incentives are fully withdrawn.National Institute for Health Research (NIHR

Recruitment of Indigenous Australians with linguistic and numeric disadvantages

Recruitment challenges for mining corporations operating in Australia have intensified with the increasing global demand for mineral resources and the 1993 Native Title legislation compelling negotiated land use agreements. A finite labour pool, further compressed by an ageing and retiring workforce, competition for labour, a poor industry image as well as a requirement for applicants to possess particular educational and vocational competencies has not been offset by greater Indigenous participation, despite training provisions being a feature of land use agreements. This paper presents an analysis of a novel recruitment technique that is devoid of the need for English literacy and numeracy skills, for Indigenous people with expectations to be employed in the extensive mining operations at Nhulunbuy on the Gove Peninsula of the Northern Territory (NT) of Australia. Predicating the scheme design was a comprehensive literature reporting that the English literacy and numeracy skills likely to be held by Australian Indigenous people would preclude them from usefully participating in standard Western recruitment procedures. Analyses reveal that the scheme is a robust predictor of sustainable employment. This leads to a line of reasoning that discriminatory recruitment practices can be substituted with alternative methods to identify human work related potential and, subsequently, address economic challenges and social dislocation of marginalised Indigenous groups

Withdrawing performance indicators: retrospective analysis of general practice performance under UK Quality and Outcomes Framework

Objectives To investigate the effect of withdrawing incentives on recorded quality of care, in the context of the UK Quality and Outcomes Framework pay for performance scheme. Design Retrospective longitudinal study. Setting Data for 644 general practices, from 2004/05 to 2011/12, extracted from the Clinical Practice Research Datalink. Participants All patients registered with any of the practices over the study period—13 772 992 in total. Intervention Removal of financial incentives for aspects of care for patients with asthma, coronary heart disease, diabetes, stroke, and psychosis. Main outcome measures Performance on eight clinical quality indicators withdrawn from a national incentive scheme: influenza immunisation (asthma) and lithium treatment monitoring (psychosis), removed in April 2006; blood pressure monitoring (coronary heart disease, diabetes, stroke), cholesterol concentration monitoring (coronary heart disease, diabetes), and blood glucose monitoring (diabetes), removed in April 2011. Multilevel mixed effects multiple linear regression models were used to quantify the effect of incentive withdrawal. Results Mean levels of performance were generally stable after the removal of the incentives, in both the short and long term. For the two indicators removed in April 2006, levels in 2011/12 were very close to 2005/06 levels, although a small but statistically significant drop was estimated for influenza immunisation. For five of the six indicators withdrawn from April 2011, no significant effect on performance was seen following removal and differences between predicted and observed scores were small. Performance on related outcome indicators retained in the scheme (such as blood pressure control) was generally unaffected. Conclusions Following the removal of incentives, levels of performance across a range of clinical activities generally remained stable. This indicates that health benefits from incentive schemes can potentially be increased by periodically replacing existing indicators with new indicators relating to alternative aspects of care. However, all aspects of care investigated remained indirectly or partly incentivised in other indicators, and further work is needed to assess the generalisability of the findings when incentives are fully withdrawn

An experimental study of the applicability of flooding phenomena to the dynamic lubrication method of well control

This research investigates the feasibility of the dynamic lubrication method of well control as an alternative to conventional stepwise lubrication. The applicability of flooding phenomena to dynamic lubrication and its use in an optimization method to maximize pumping rates was also investigated. An experimental approach was taken in which experiments were conducted in a 13’ long laboratory apparatus designed to emulate the geometry in a wellhead and also in a full-scale research well. The laboratory experiments were conducted to visually investigate the mechanism of flooding and derive a flooding correlation applicable to this type of system. The full-scale experiments were done to evaluate the dynamic lubrication method, compare it to conventional lubrication, attempt dynamic lubrication at high pumping rates, assess the applicability of flooding as the rate determining phenomenon, and identify any complications encountered during this process. The laboratory tests produced a correlation that was applicable over a range of 3 annular sizes. The equation resembled correlations from previous studies by Richter (1981) and Dempster(1984) and used dimensionless volumetric fluxes as the non-dimensional parameter. The full-scale tests showed that dynamic lubrication was more efficient in removing gas trapped at the wellhead, and reduced the severity of pressure fluctuations inherent in conventional stepwise lubrication. Pumping at constant high rates had an adverse effect on the process. This high pumping rate reduced the rate of accumulation of liquid in the well by 50% when compared to the more conservative pumping rates. The boundary between efficient and inefficient pump rates corresponded well to the correlation from laboratory tests if the relevant dimensions were assumed to be dependent on wellhead geometry. For this wellhead, the casing-casing annulus has a smaller cross sectional area and therefore higher velocities, which logically should control flooding. However, using the casing annulus geometry in the flooding correlation results in incorrect prediction of the onset of flooding unless revised coefficients are used. These revised coefficients were adopted for a proposed preliminary optimization method

OPERATION AND PROCESS CONTROL DEVELOPMENT FOR A PILOT-SCALE LEACHING AND SOLVENT EXTRACTION CIRCUIT RECOVERING RARE EARTH ELEMENTS FROM COAL-BASED SOURCES

The US Department of Energy in 2010 has identified several rare earth elements as critical materials to enable clean technologies. As part of ongoing research in REEs (rare earth elements) recovery from coal sources, the University of Kentucky has designed, developed and is demonstrating a ¼ ton/hour pilot-scale processing plant to produce high-grade REEs from coal sources. Due to the need to control critical variables (e.g. pH, tank level, etc.), process control is required. To ensure adequate process control, a study was conducted on leaching and solvent extraction control to evaluate the potential of achieving low-cost REE recovery in addition to developing a process control PLC system. The overall operational design and utilization of Six Sigma methodologies is discussed. Further, the application of the controls design, both procedural and electronic for the control of process variables such as pH is discussed. Variations in output parameters were quantified as a function of time. Data trends show that the mean process variable was maintained within prescribed limits. Future work for the utilization of data analysis and integration for data-based decision-making will be discussed

Optimisation and validation of a tri-axial bioreactor for nucleus pulposus tissue engineering

Mechanical stimulation, in combination with biochemical factors, is likely to be essential to the appropriate function of stem cells and the development of tissue engineered constructs for orthopaedic and other uses. A multi-axial bioreactor was designed and built by Bose ElectroForce to simulate physiologically relevant loading conditions of the intervertebral disc (IVD), including axial compression, hydrostatic pressure and perfusion flow to multiple constructs under the control of a software program. This research optimises the design and configuration of the perfusion system of the bioreactor and presents results of preliminary experimental work on the combined effects of axial compression and perfusion on the viability of mesenchymal stem cells encapsulated in alginate hydrogels and the ability of the cells to produce extracellular matrix (ECM). The results of this thesis illustrated the power of a design of experiments (DOE) approach as a troubleshooting quality tool. With a modest amount of effort, we have gained a better understanding of the perfusion process of the tri-axial bioreactor, improved operational procedures and reduced variation in the process. Furthermore, removing unnecessary tubing lengths, equipment and fittings has made cost savings. The steady flow energy equation (SFEE) was used to develop a numerical analysis framework that provides an insight into the balance between velocity, elevation and friction in the flow system. The pressure predictions agreed well with experimental data, thus validating the SFEE for fluid analysis in the bioreactor system. The numerical predictions can be used to estimate the pressures around the three-dimensional constructs with a given arrangement of the tubing and components of the bioreactor. The system can potentially support long-term cultures of cell-seeded constructs in controlled environmental conditions found in vivo to study the mechanobiology of nucleus pulposus tissue engineering and the aetiology of IVD degeneration. However, dynamic compression and perfusion with associated hydrostatic pressurization of culture medium resulted in significant loss of cell viability compared to the unstimulated controls. Due to a large number of factors affecting cell behaviour in the tri-axial bioreactor system, it is difficult to identify the exact parameters influencing the observed cell response. A strategy that could help to distinguish the effects of mechanical stimuli and specific physiochemical factors should combine experiments with mathematical modelling approaches, and use the sensing incorporated in the bioreactor design and process-control systems to monitor and control specific culture parameters. Optimisation of the cell passage and cell seeding density were identified as key areas to improve the production of GAG in future studies; since the production of ECM was not observed in both static and dynamic cultures. Further studies could also attempt to use other hydrogel scaffolds, such as agarose, which has been widely used in cartilage tissue engineering studies and hyaluronic acid - a component of the nucleus pulposus ECM