Development of a diagnostic sensor for measuring blood cell concentrations during haemoconcentration

Background: HemoSep® is a commercial ultrafiltration and haemoconcentration device for the concentration of residual bypass blood following surgery. This technology is capable of reducing blood loss in cardiac and other types of "clean site" procedures, including paediatric surgery. Clinical feedback suggested that the device would be enhanced by including a sensor technology capable of discerning the concentration level of the processed blood product. We sought to develop a novel sensor that can, using light absorption, give an accurate estimate of packed cell volume (PCV). Materials and methods: A sensor-housing unit was 3D printed and the factors influencing the sensor's effectiveness – supply voltage, sensitivity and emitter intensity - were optimised. We developed a smart system, using comparator circuitry capable of visually informing the user when adequate PCV levels (⩾35%) are attained by HemoSep® blood processing, which ultimately indicates that the blood is ready for autotransfusion. Results: Our data demonstrated that the device was capable of identifying blood concentration at and beyond the 35% PCV level. The device was found to be 100% accurate at identifying concentration levels of 35% from a starting level of 20%. Discussion: The sensory capability was integrated into HemoSep's® current device and is designed to enhance the user’s clinical experience and to optimise the benefits of HemoSep® therapy. The present study focused on laboratory studies using bovine blood. Further studies are now planned in the clinical setting to confirm the efficacy of the device

Users` experiences of heroin and methadone treatment

The present study, conducted in 2003, Melbourne, Australia, examined and compared how different personal and social resources related to participants\u27 use of both heroin and methadone, as well as their experiences of stigma and program regulation, and their evaluation of methadone treatment. In-depth interviews were conducted with 10 participants (five men, five women) aged between 25 and 42. Participants who had diverse personal and social circumstances were purposefully sought. Findings showed that users with &ldquo;non-addict&rdquo; or &ldquo;functional&rdquo; self-concepts had more resources and supportive social relationships that assisted them to develop realistic treatment expectations, avoid the stigma associated with methadone, and focus on the benefits of the treatment. Conversely, &ldquo;conflicted&rdquo; users with limited resources, few social connections, and negative self-concept saw methadone as an addiction, and as a highly stigmatizing and disempowering intervention. Social policies that differentiate users and address ways of improving users\u27 personal and social resources are now needed.<br /

Hemodynamics in the pulmonary bifurcation : effect of geometry and boundary conditions

Introduction Pulmonary regurgitation [1] and obstruction in the left pulmonary artery [2], the most common complications affecting adult patients with repaired tetralogy of Fallot, are known to lead to right ventricular dilatation and dysfunction. Long-term pulmonary stenosis is also hypothesized to lead to abnormal lung development and elevated pulmonary vascular resistance [3]. Pulmonary valve replacement is deemed necessary in these patients, but the optimal timing to perform the surgery is still ambiguous [1]. The aim of this study is to numerically investigate the blood flow development in the pulmonary bifurcation of adult patients with congenital heart defects. In this work, we present results from a parametric analysis, where the effect of geometry (branch angle, origin, branch obstruction) and boundary conditions (unsteady flow, Reynolds number, pressure difference at the outlets, and non-Newtonian models) were examined. Methods Blood flow simulations were performed in simplified models of the pulmonary bifurcation, using a validated finite volume scheme in OpenFOAM®. Physiological and pathological conditions were assumed and local velocities, wall shear stress values, velocity and pressure distributions were evaluated. The fluid was considered incompressible and governed by the Newtonian Navier-Stokes equations. The Power Law, CrossPower Law, the Casson, and the Bird-Carreau non-Newtonian models were also investigated. Results & Discussion Blood flow in the pulmonary bifurcation is highly dependent on the local geometrical characteristics and the boundary conditions assumed. Flow separation increases with the branching angle, the branch origin, and stenosis. Branch obstruction and boundary conditions have, further, a significant effect on velocities and shear stresses developed on the vessel wall. The presence of peripheral stenosis and pressure difference at the branch outlets affects significantly the flow splits in the daughter branches. Finally, pressure ratios are considered to provide a good indication of flow discrepancies between the different cases tested. Evaluation of the results on more complex 3D anatomically-correct geometries is necessary. Future work will involve reconstruction of patient-specific models using CT and MRI data from adult patients with congenital heart diseases. More realistic boundary conditions will also be considered, including the pulsatile nature of blood flow and Windkessel models at the branch outlets to account for peripheral resistance. Conclusion Computational fluid dynamics tools have been utilised in this study to investigate the effect of a range of different geometrical characteristics and boundary conditions. The main findings of this study concern a new effect of the branch origin, and a notable branch flow split analysis under conditions of peripheral stenosis and pressure difference in the branch outlets. Acknowledgments This work is supported in part by the University of Strathclyde Research Studentship Scheme (SRSS) Research Excellence Awards (REA), Project No 1208 and the European Union’s Horizon 2020 research and innovation programme, under the Marie Skłodowska-Curie grant agreement No 749185. References 1. Kogon B.E. et al. Seminars in Thoracic and Cardiovascular Surgery 2015; 27:57-64. 2. McElhinney D.B. et al. The Annals of Thoracic Surgery 1998; 65:1120-1126. 3. Harris M.A. et al. Cardiovascular Imaging 2011; 4:506-513

A bilateral shear layer between two parallel Couette flows

We consider a shear layer of a kind not previously studied to our knowledge. Contrary to the classical free shear layer, the width of the shear zone does not vary in the streamwise direction but rather exhibits a lateral variation. Based on some simplifying assumptions, an analytic solution has been derived for the new shear layer. These assumptions have been justified by a comparison with numerical solutions of the full Navier-Stokes equations, which accord with the analytical solution to better than 1% in the entire domain. An explicit formula is found for the width of the shear zone as a function of wall-normal coordinate. This width is independent of wall velocities in the laminar regime. Preliminary results for a co-current laminar-turbulent shear layer in the same geometry are also presented. Shear-layer instabilities were then developed and resulted in an unsteady mixing zone at the interface between the two co-current streams.Comment: 6 pages, 7 figures. Accepted for publication in Phys. Rev.

Harnessing heterogeneous nucleation to control tin orientations in electronic interconnections

While many aspects of electronics manufacturing are controlled with great precision, the nucleation of tin in solder joints is currently left to chance. This leads to a widely varying melt undercooling and different crystal orientations in each joint which results in a different resistance to electromigration, thermomechanical fatigue and other failure modes in each joint. Here we identify a family of nucleants for tin, prove their effectiveness using a novel droplet solidification technique, and demonstrate an approach to incorporate the nucleants into solder joints to control the orientation of the tin nucleation event. With this approach, it is possible to change tin nucleation from a stochastic to a deterministic process, and to generate single crystal joints with their c-axis orientation tailored to best combat a selected failure mode

Patient-specific blood flow simulations in the pulmonary bifurcation of patients with tetralogy of fallot

Dysfunction of the pulmonary valve and narrowing of the branch pulmonary arteries are common chronic complications in adult patients with tetralogy of Fallot; the most common cyanotic congenital heart disease with an estimate prevalence 1 in 3000 live births. Clinical consequences include, but are not limited to, abnormal lung development and elevated pulmonary vascular resistance. It is, therefore, crucial to better understand and characterise the haemodynamic environment in the pulmonary bifurcation to better diagnose and treat these patients. In this study, we have focused on investigating the blood flow dynamics in patient-specific geometries of the pulmonary bifurcation by means of computational models

The antibacterial efficacy of far-UVC light : a combined-method study exploring the effects of experimental and bacterial variables on dose-response

Far-ultraviolet C light, with a wavelength of 200–230 nm, has demonstrated broad-spectrum germicidal efficacy. However, due to increased interest in its use as an alternative antimicrobial, further knowledge about its fundamental bactericidal efficacy is required. This study had two objectives. Firstly, it investigated experimentally the Far-UVC dose–response of common bacteria suspended at various cell densities in transparent buffer, ensuring no influence from photosensitive suspending media. Increasing doses of Far-UVC were delivered to Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus in PBS at 101, 102, 103, 105 and 107 CFU·mL−1, with surviving colony-forming units enumerated (n ≥ 3). Secondly, through a systematised literature review, this work sought to explore the impact of genus/species, Gram type, cell form, cell density and irradiance on dose–response. The screening of 483 publications was performed with 25 included in the study. Data for 30 species were collated, analysed and compared with the experimental results. Overall, Gram-positive species showed greater resilience to Far-UVC than Gram-negative; some inter-species and inter-genera differences in resilience were identified; endospores were more resilient than vegetative cells; the results suggested that inactivation efficiency may decrease as cell density increases; and no significant correlation was identified between irradiance and bactericidal dose effect. In conclusion, this study has shown Far-UVC light to be an effective decontamination tool against a vast range of bacterial vegetative cells and endospores

Underwater sound of rigid-hulled inflatable boats

Underwater sound of rigid-hulled inflatable boats was recorded 142 times in total, over 3 sites: 2 in southern British Columbia, Canada, and 1 off Western Australia. Underwater sound peaked between 70 and 400 Hz, exhibiting strong tones in this frequency range related to engine and propeller rotation. Sound propagation models were applied to compute monopole source levels, with the source assumed 1m below the sea surface. Broadband source levels (10–48 000Hz) increased from 134 to 171 dB re 1μPa @ 1m with speed from 3 to 16m/s (10–56 km/h). Source power spectral density percentile levels and 1/3 octave band levels are given for use in predictive modeling of underwater sound of these boats as part of environmental impact assessments