Erratum to: Determination of metal ion content of beverages and estimation of target hazard quotients: a comparative study

This is a correction to the following paper: Hague T, Petroczi A, Andrews PR, Barker J, Naughton DP: Determination of metal ion content of beverages and estimation of target hazard quotients: a comparative study. Chem Central J 2008, 2:13.     

Determination of metal ion content of beverages and estimation of target hazard quotients: a comparative study

Background  

Considerable research has been directed towards the roles of metal ions in nutrition with metal ion toxicity attracting particular attention. The aim of this study is to measure the levels of metal ions found in selected beverages (red wine, stout and apple juice) and to determine their potential detrimental effects via calculation of the Target Hazard Quotients (THQ) for 250 mL daily consumption.     

Three-dimensional magnetic resonance velocimetry measurements of turbulence quantities in complex flow

A magnetic resonance velocimetry (MRV) experimental technique based on magnetic resonance imaging and capable of measuring the turbulent Reynolds stresses in a 3D flow domain is described. Results are presented in backward facing step flow in a square channel with a Reynolds number of 48,000 based on step height and freestream velocity at the step. MRV results are compared to particle image velocimetry (PIV) measurements in the centerplane containing the streamwise and cross-stream axes. MRV and PIV mean velocity measurements show excellent agreement. MRV measurements for Reynolds normal stresses compare to within ±20% of the PIV results while results for the turbulent shear are less accurate.     

Sinusoidal crossflow microfiltration device--experimental and computational flowfield analysis

We present an analysis of the flowfield inside a novel crossflow microfiltration device. The filter performance relies on shear focusing by means of a corrugated channel. The flow and shear stress characteristics inside the filter are studied by means of both micro Particle Image Velocimetry (micro-PIV) measurements and Computational Fluid Dynamics (CFD) analysis. We show that an increase of the shear rate by 55-85% as compared to a straight channel geometry is achieved for crossflow velocities ranging from 0.05 m s(-1)-0.8 m s(-1)(Re 5-70). This substantial increase in the local wall shear may improve filter performance in terms of reduced clogging and cell cake formation as compared to conventional crossflow filtration devices. Our current investigation, along with the fact that the filter employs no complex, three dimensional geometrical patterns, advanced pumping schemes, nor has a need for costly assembly and sealing procedures, indicates that the sinusoidal crossflow microfiltration module may serve as a technically and economically feasible solution for integrated lab-on-a-chip devices. Furthermore, the presented approach of shear-focusing may be beneficial in other bio-chemical contexts, such as cell lysis and surface chemistry.     

Selective seeding for micro-PIV

A novel seeding method for microscale particle image velocimetry (micro-PIV) is presented. The method relies on selective seeding of a thin fluid layer within an otherwise particle-free flow. In analogy to the laser sheet in macroscale PIV, the generated particle sheet defines both the depth and the position of the measurement plane, independent of the details of the optical setup. Selectively seeded micro-PIV is applied to measure the instantaneous velocity field in a microchannel with a depth-wise resolution 20% below the estimated optical measurement depth of the micro-PIV system. In principle, a measurement depth corresponding to the diameter of the tracer particles may be achieved.

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