scholarly journals Resonant Mixing in Glass Bowl Microbioreactor Investigated by Microparticle Image Velocimetry

Micromachines ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 284 ◽  
Author(s):  
Sven Meinen ◽  
Lasse Jannis Frey ◽  
Rainer Krull ◽  
Andreas Dietzel
Keyword(s):  
Surface Waves ◽  
Growth Conditions ◽  
Capillary Surface ◽  
Mixing Conditions ◽  
Glass Slides ◽  
Image Velocimetry ◽  
Resonance Frequencies ◽  
Microparticle Image Velocimetry ◽  
Growing Conditions ◽  
Vortex Patterns

Microbioreactors are gaining increased interest in biopharmaceutical research. Due to their decreasing size, the parallelization of multiple reactors allows for simultaneous experiments. This enables the generation of high amounts of valuable data with minimal consumption of precious pharmaceutical substances. However, in bioreactors of all scales, fast mixing represents a crucial condition. Efficient transportation of nutrients to the cells ensures good growing conditions, homogeneous environmental conditions for all cultivated cells, and therefore reproducible and valid data. For these reasons, a new type of batch microbioreactor was developed in which any moving mixer component is rendered obsolete through the utilization of capillary surface waves for homogenization. The bioreactor was fabricated in photosensitive glass and its fluid volume of up to 8 µL was provided within a bowl-shaped volume. External mechanical actuators excited capillary surface waves and stereo microparticle image velocimetry (µPIV) was used to analyze resulting convection at different excitation conditions in varied reactor geometries. Typical vortex patterns were observed at certain resonance frequencies where best mixing conditions occurred. Based on the results, a simplified 1D model which predicts resonance frequencies was evaluated. Cultivation of Escherichia coli BL21 under various mixing conditions showed that mixing in resonance increased the biomass growth rate, led to high biomass concentrations, and provided favorable growth conditions. Since glass slides containing multiple bowl reactors can be excited as a whole, massive parallelization is foreseen.

scholarly journals Bioactive Compounds, Antioxidant Activity and Growth Behavior in Lettuce Cultivars Grown under Field and Greenhouse Conditions

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 52
Author(s):  
Melisa Lanza Volpe ◽  
Verónica C. Soto Vargas ◽  
Anabel Morón ◽  
Roxana E. González
Keyword(s):  
Antioxidant Activity ◽  
Bioactive Compounds ◽  
Antioxidant Activities ◽  
Growth Conditions ◽  
Growth Behavior ◽  
Total Phenolic ◽  
Spectrophotometric Methods ◽  
Leafy Greens ◽  
Growing Conditions ◽  
Field Production

Lettuce (Lactuca sativa L.) is one of the most important leafy greens worldwide. The nutritional value of its edible leaf depends on different factors including type and growing conditions. The aim was to determine the bioactive compounds content, antioxidant activity and growth behavior of twenty-two lettuce genotypes, cultivated under field and greenhouse conditions. Total phenolic compound, chlorophylls, carotenoids, anthocyanin contents and antioxidant activities were analyzed by spectrophotometric methods. Data were analyzed by analysis of variance (ANOVA). Significant differences between bioactive compounds, antioxidant activity and growth behavior were found among cultivars and morphological types, for both growth conditions. Carotenoid and chlorophyll content was higher in greenhouse conditions for all genotypes. In field production, butterhead and iceberg lettuces showed lower content of these bioactive compounds. The red-pigmented Falbala cultivar from field production showed the highest level of polyphenols and anthocyanin. Meanwhile, in greenhouse conditions, the oak leaf cultivar Grenadine displayed the highest concentration of these phenolic compounds. The iceberg type lettuce showed the lowest percentages of antioxidant activity in both environments. The results showed the effect of growing conditions and the high variability in lettuce bioactive compounds content and antioxidant activity among the different types.

scholarly journals Accelerated Particle Separation in a DLD Device at Re > 1 Investigated by Means of µPIV

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 768 ◽  
Author(s):  
Jonathan Kottmeier ◽  
Maike Wullenweber ◽  
Sebastian Blahout ◽  
Jeanette Hussong ◽  
Ingo Kampen ◽  
...  
Keyword(s):  
Lateral Displacement ◽  
Fluid Dynamic ◽  
Particle Diameter ◽  
Reynolds Numbers ◽  
Field Pattern ◽  
Cfd Simulations ◽  
Deterministic Lateral Displacement ◽  
Tracer Particles ◽  
Image Velocimetry ◽  
Microparticle Image Velocimetry

A pressure resistant and optically accessible deterministic lateral displacement (DLD) device was designed and microfabricated from silicon and glass for high-throughput fractionation of particles between 3.0 and 7.0 µm comprising array segments of varying tilt angles with a post size of 5 µm. The design was supported by computational fluid dynamic (CFD) simulations using OpenFOAM software. Simulations indicated a change in the critical particle diameter for fractionation at higher Reynolds numbers. This was experimentally confirmed by microparticle image velocimetry (µPIV) in the DLD device with tracer particles of 0.86 µm. At Reynolds numbers above 8 an asymmetric flow field pattern between posts could be observed. Furthermore, the new DLD device allowed successful fractionation of 2 µm and 5 µm fluorescent polystyrene particles at Re = 0.5–25.

A Microparticle Image Velocimetry Based on Light Field Imaging

2019 ◽  
Vol 19 (21) ◽  
pp. 9806-9817 ◽  
Author(s):  
Xianglei Song ◽  
Mengtao Gu ◽  
Lixia Cao ◽  
Zhiyong Tang ◽  
Chuanlong Xu
Keyword(s):  
Light Field ◽  
Image Velocimetry ◽  
Microparticle Image Velocimetry ◽  
Light Field Imaging ◽  
Field Imaging

Exposure of internal waves on the sea surface

2009 ◽  
Vol 626 ◽  
pp. 1-20 ◽  
Author(s):  
HWUNG-HWENG HWUNG ◽  
RAY-YENG YANG ◽  
IGOR V. SHUGAN
Keyword(s):  
Surface Wave ◽  
Internal Wave ◽  
Surface Waves ◽  
Internal Waves ◽  
High Frequency ◽  
Numerical Solutions ◽  
Wave Excitation ◽  
Resonance Frequencies ◽  
The Impact ◽  
Current Zone

We theoretically analyse the impact of subsurface currents induced by internal waves on nonlinear Stokes surface waves. We present analytical and numerical solutions of the modulation equations under conditions that are close to group velocity resonance. Our results show that smoothing of the downcurrent surface waves is accompanied by a relatively high-frequency modulation, while the profile of the opposing current is reproduced by the surface wave's envelope. We confirm the possibility of generating an internal wave forerunner that is a modulated surface wave packet. Long surface waves can create such a wave modulation forerunner ahead of the internal wave, while other relatively short surface waves comprise the trace of the internal wave itself. Modulation of surface waves by a periodic internal wavetrain may exhibit a characteristic period that is less than the internal wave period. This period can be non-uniform while the wave crosses the current zone. Our results confirm that surface wave excitation by means of internal waves, as observed at their group resonance frequencies, is efficient only in the context of opposing currents.

Experimental Analysis of Microchannel Entrance Length Characteristics Using Microparticle Image Velocimetry

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Tariq Ahmad ◽  
Ibrahim Hassan
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Entrance Region ◽  
Working Fluid ◽  
Parallel Plates ◽  
Entrance Length ◽  
Number Range ◽  
Micro Piv ◽  
Image Velocimetry ◽  
Microparticle Image Velocimetry

The study of the entrance region of microchannels and microdevices is limited, yet important, since the effect on the flow field and heat transfer mechanisms is significant. An experimental study has been carried out to explore the laminar hydrodynamic development length in the entrance region of adiabatic square microchannels. Flow field measurements are acquired through the use of microparticle image velocimetry (micro-PIV), a nonintrusive particle tracking and flow observation technique. With the application of micro-PIV, entrance length flow field data are obtained for three different microchannel hydraulic diameters of 500 μm, 200 μm, and 100 μm, all of which have cross-sectional aspect ratios of 1. The working fluid is distilled water, and velocity profile data are acquired over a laminar Reynolds number range from 0.5 to 200. The test-sections were designed as to provide a sharp-edged microchannel inlet from a very large reservoir at least 100 times wider and higher than the microchannel hydraulic diameter. Also, all microchannels have a length-to-diameter ratio of at least 100 to assure fully developed flow at the channel exit. The micro-PIV procedure is validated in the fully developed region with comparison to Navier–Stokes momentum equations. Good agreement was found with comparison to conventional entrance length correlations for ducts or parallel plates, depending on the Reynolds range, and minimal influence of dimensional scaling between the investigated microchannels was observed. New entrance length correlations are proposed, which account for both creeping and high laminar Reynolds number flows. These correlations are unique in predicting the entrance length in microchannels and will aid in the design of future microfluidic devices.

scholarly journals Liana infestation impacts tree growth in a lowland tropical moist forest

2009 ◽  
Vol 6 (2) ◽  
pp. 3133-3158 ◽  
Author(s):  
G. M. F. van der Heijden ◽  
O. L. Phillips
Keyword(s):  
Tropical Forests ◽  
Tree Growth ◽  
Atmospheric Carbon Dioxide ◽  
Dry Weight ◽  
Growth Conditions ◽  
Linear Mixed Effect Model ◽  
Mixed Effect ◽  
Individual Tree ◽  
Rate Of Increase ◽  
Growing Conditions

Abstract. Stand-level estimates of the effect of lianas on tree growth in mature tropical forests are needed to evaluate the functional impact of lianas and their potential to affect the ability of tropical forests to sequester carbon, but these are currently lacking. Using data collected on tree growth rates, local growing conditions and liana competition in five permanent sampling plots in Amazonian Peru, we present the first such estimates of the effect of lianas on above-ground productivity of trees. By constructing a multi-level linear mixed effect model to predict individual tree diameter growth model using individual tree growth conditions, we were able to estimate stand-level above-ground biomass (AGB) increment in the absence of lianas. We show that lianas, mainly by competing above-ground with trees, reduce tree annual above-ground stand-level biomass by ~10%, equivalent to 0.51 Mg dry weight ha−1 yr−1 or 0.25 Mg C ha−1 yr−1. AGB increment of lianas themselves was estimated to be 0.15 Mg dry weight ha−1 yr−1 or 0.07 Mg C ha−1 yr−1, thus only compensating ~29% of the liana-induced reduction in stand-level AGB increment. Increasing liana pressure on tropical forests may therefore not only reduce their carbon storage capacity, by indirectly promoting tree species with low-density wood, but also their rate of carbon uptake, with potential consequences for the rate of increase in atmospheric carbon dioxide.

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