Streak Line
Streak Line - Related Videos
09:03
Pure Cultures and Streak Plating: Isolation of Single Bacterial Colonies from a Mixed Sample
0 Views •
2023
Source: Tilde Andersson1, Rolf Lood1 1 Department of Clinical Sciences Lund, Division of Infection Medicine, Biomedical Center, Lund University, 221 00 Lund, Sweden Seemingly impossible to determine, microbial biodiversity is truly astounding with an estimated one trillion coexisting species (1,2). Although particularly harsh climates, like the acidic environment of the human stomach (3) or the subglacial lakes of Antarctica (4), may be dominated by a specific species, bacteria are typically...
10:33
Assessing Cell Viability and Death in 3D Spheroid Cultures of Cancer Cells
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Cited by 34 •
2019
Here, we present several simple methods for evaluating viability and death in 3D cancer cell spheroids, which mimic the physico-chemical gradients of in vivo tumors much better than the 2D culture. The spheroid model, therefore, allows evaluation of the cancer drug efficacy with improved translation to in vivo conditions.
03:03
Phenotypic Comparison of Wild-Type and Mutant Strains of Streptomyces coelicolor
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2025
Source: Bennett, J. A., et al. Visual and Microscopic Evaluation of Streptomyces Developmental Mutants. J. Vis. Exp. (2018)This video demonstrates the cultivation and phenotypic comparison of wild-type and mutant Streptomyces coelicolor strains. It outlines procedures for minimizing spontaneous mutations, preventing cross-contamination, and promoting bacterial growth through proper plating techniques. Finally, the video highlights visual differences in colony morphology to illustrate the...
10:53
Serial Dilutions and Plating: Microbial Enumeration
0 Views •
2023
Source: Jonathan F. Blaize1, Elizabeth Suter1, and Christopher P. Corbo1 1 Department of Biological Sciences, Wagner College, 1 Campus Road, Staten Island NY, 10301 Quantitative assessment of prokaryotes can be onerous given their abundance, propensity for exponential proliferation, species diversity within a population, and specific physiological needs. Compounding this challenge, is the four-phase nature in which bacteria replicate (lag, log, stationary and death). The ability to accurately...
02:51
Isolation and Cultivation of Caenorhabditis elegans-Associated Bacteria
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2026
Source: Petersen, C. et. al., Isolation and Characterization of the Natural Microbiota of the Model Nematode Caenorhabditis elegans. J. Vis. Exp. (2022)This video demonstrates the isolation and cultivation of bacterial species associated with Caenorhabditis elegans. A bead-based lysis of C. elegans, followed by selective culturing, enables the isolation of diverse microbial strains for further analysis.
FAQs
The three descriptions coincide in steady flow because the velocity field does not change with time. Under unsteady conditions, they can form different patterns: a streak line records particles released successively at one fixed location, whereas streamlines describe the instantaneous velocity field and pathlines follow individual particles. This distinction helps engineers interpret whether an observed tracer pattern represents persistent or time-varying flow behavior.
A tracer introduced continuously at a stationary point is carried downstream by the local velocity field. Dye, smoke, or another visible substance therefore records the changing positions of particles that passed through that location at different times. The resulting pattern provides a time-dependent visual record, allowing engineers to relate the observed shape to motion within the surrounding flow.
Streak-line patterns can reveal recirculation, where fluid motion returns within a region, and separation, where the flow departs from an expected surface-following behavior. They can also indicate how substances mix as they move through a flow. These visual observations help characterize the velocity field and provide qualitative evidence about important flow structures.
Engineers continuously introduce dye, smoke, or another tracer at a fixed point and observe the pattern that develops downstream. The stationary release location is important because it ensures that the visible record comes from particles passing through one defined position. The resulting pattern can then be examined to characterize motion, recirculation, separation, or mixing.
Streak lines support flow investigations in settings such as wind tunnels and process engineering systems. In a wind tunnel, visible tracer patterns help engineers examine motion around or through a test configuration. In process engineering, they help assess how material moves and mixes. In both contexts, the method offers a direct visual complement to flow analysis.
Engineers can compare the tracer pattern observed in an experiment with the flow structures predicted by a computational fluid dynamics model. Agreement can support the model's representation of the velocity field, while differences may identify areas requiring further investigation. Recirculation, separation, and mixing patterns are especially useful comparison features because they are visible in the observed flow.