Influence of Long-Distance Bicycle Riding on Serum/Urinary Biomarkers of Prostate Cancer

Herein, we present a study focused on the determination of the influence of long-distance (53 km) bicycle riding on levels of chosen biochemical urinary and serum prostate cancer (PCa) biomarkers total prostate-specific antigen (tPSA), free PSA (fPSA) and sarcosine. Fourteen healthy participants with no evidence of prostate diseases, in the age range from 49–57 years with a median of 52 years, underwent physical exercise (mean race time of 150 ± 20 min, elevation increase of 472 m) and pre- and post-ride blood/urine sampling. It was found that bicycle riding resulted in elevated serum uric acid (p = 0.001, median 271.76 vs. 308.44 µmol/L pre- and post-ride, respectively), lactate (p = 0.01, median 2.98 vs. 4.8 mmol/L) and C-reactive protein (p = 0.01, 0.0–0.01 mg/L). It is noteworthy that our work supports the studies demonstrating an increased PSA after mechanical manipulation of the prostate. The subjects exhibited either significantly higher post-ride tPSA (p = 0.002, median 0.69 vs. 1.1 ng/mL pre- and post-ride, respectively) and fPSA (p = 0.028, median 0.25 vs. 0.35 ng/mL). Contrary to that, sarcosine levels were not significantly affected by physical exercise (p = 0.20, median 1.64 vs. 1.92 µmol/mL for serum sarcosine, and p = 0.15, median 0.02 µmol/mmol of creatinine vs. 0.01 µmol/mmol of creatinine for urinary sarcosine). Taken together, our pilot study provides the first evidence that the potential biomarker of PCa—sarcosine does not have a drawback by means of a bicycle riding-induced false positivity, as was shown in the case of PSA.     

RHEOLOGICAL PROPERTIES OF SUSPENSIONS OF SOLID SPHERES IN NON-NEWTONIAN FLUIDS

A theoretical expression based on the cell model has been developed to predict the dependence of the flow properties of a suspension in a wide range of solids concentration when the dispersing medium is a non-Newtonian liquid. Theoretical predictions show that the increase of the relative consistency coefficient of a suspension with increasing particle concentration is less dramatic when the flow index of the suspending medium is lower. Comparison with published data shows that the predictions of the present model for the relative consistency coefficient of a suspension in a non-Newtonian fluid are fairly accurate.     

Turbulent mass transfer in the mass transfer entry region for non-newtonian fluids

The effect of non-Newtonian flow behavior on turbulent mass transfer in the mass transfer entry region is investigated analytically. The predicted mass transfer rates in the mass transfer entry region are in good agreement with available experimental data and empirical correlations. The theoretical results for drag-reducing fluids show about 30 – 50% mass transfer rate reduction in the entry region which is less than that in the fully developed region.     

VELOCITY PROFILES OF NEWTONIAN AND NON-NEWTONIAN TOROIDAL FLOWS MEASURED BY A LDA TECHNIQUE

Laser Doppler Anemomeiry was used to measure the primary (axial) and secondary (recirculating) velocity profiles in laminar flows of Newtonian (ethylene glycol) and non-Newtonian (aqueous solutions of CMC and PAA) liquids in curved tubes. Rheological characteristics of these liquids were measured using standard viscometric techniques (Haake and Mechanical Spectrometer). The effect of the shear-thinning viscosity is to flatten the axial velocity profile while enhancing the circulating flow close to the walls. On the other hand, the viscoelasticity reduces the extent of the secondary flow for all Dean numbers. This fact explains the reduction of laminar friction reported in the literature.

The primary and secondary velocity profiles, which appear to be the first ones ever published for the toroidal flows, are compared with the predictions of numerical simulation. The agreement is good when comparing the profiles of the axial flow but it is unsatisfactory for the secondary flows.     

Flow characterization in T-shaped and cross-shaped micromixers

The understanding of physical phenomena such as flow behaviour and mass transfer performance is needed in order to develop appropriate micromixers for industrial or biomedical applications. In this article, the flow behaviour of the T-shaped and the cross-shaped micromixers with square cross-section are studied through numerical and experimental investigations. The comparisons are based on identical treated fluxes. From the particle image velocimetry (PIV) measurements, the flow topologies in the T-shaped and cross-shaped micromixers are very different. After liquid impact, it is observed that the vortex structures cover a longer part of the outlet channel in the case of the cross geometry. This result indicates that the cross-shaped micromixer could improve the mixing process in comparison with the micromixers having T geometry. A second experimental technique has been used, the electrochemical one, involving microelectrodes placed at several wall positions of the cross-shaped micromixer. The electrochemical method can locally characterize the formation of swirling flows. The high values of wall shear rate, in the impact zone, confirm the near wall disturbance created by the impingement of the flow and also the appearance of vortices that could enhance fluid mixing.