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Biofilms, groups of bacteria that adhere to wet surfaces and resist antibiotics, often cause chronic infections and complications with medical devices. Despite their critical role in various environments, a significant gap remains in understanding biofilm dynamics within common ecological settings. Here, we investigate the formation and development of biofilm streamers in microfluidic channels using Pseudomonas aeruginosa PAO1 and its chemotaxis-blind mutant PC4. We find that biofilm streamers consistently form at the corners of microfluidic channels under low-speed flow conditions. We observe that higher concentrations of LB medium lead to the development of mature biofilms, while lower concentrations favor the formation of streamers. Also, the surface properties of the microfluidic channels significantly influence biofilm formation. The PEL-coated surfaces are more favorable to form biofilm streamers compared to bare glass surfaces. Furthermore, we investigate the role of chemotaxis with wild-type PAO1 strains formed streamers differently compared to the PC4 mutant, which confirms that chemotaxis significantly impacts streamer formation. These findings offer valuable insights into the physical and biological factors affecting biofilm development in microfluidic environments and provide important information for further studies on bacterial biofilms. [ABSTRACT FROM AUTHOR]

For the practical use of synthetic hydrogels as artificial biological tissues, flexible electronics, and conductive membranes, achieving requirements for specific mechanical properties is one of the most prominent issues. Here, we demonstrate superstrong, superstiff, and conductive alginate hydrogels with densely interconnecting networks implemented via simple reconstructing processes, consisting of anisotropic densification of pre-gel and a subsequent ionic crosslinking with rehydration. The reconstructed hydrogel exhibits broad ranges of exceptional tensile strengths (8–57 MPa) and elastic moduli (94–1,290 MPa) depending on crosslinking ions. This hydrogel can hold sufficient cations (e.g., Li+) within its gel matrix without compromising the mechanical performance and exhibits high ionic conductivity enough to be utilized as a gel electrolyte membrane. Further, this strategy can be applied to prepare mechanically outstanding, ionic-/electrical-conductive hydrogels by incorporating conducting polymer within the hydrogel matrix. Such hydrogels are easily laminated with strong interfacial adhesion by superficial de- and re-crosslinking processes, and the resulting layered hydrogel can act as a stable gel electrolyte membrane for an aqueous supercapacitor. Specific mechanical properties are one of the most important issues for application of synthetic hydrogels as biological tissue, flexible electronics or in conductive membranes. Here, the authors demonstrate that a reconstruction process consisting of anisotropic densification of pre-gel and subsequent ionic crosslinking and rehydration leads to strong, stiff, and conductive alginate hydrogels with densely interconnecting networks. [ABSTRACT FROM AUTHOR]

Marine plankton comprise the largest portion of the marine biomass, and play critical roles in the global carbon cycle. The carbon retention of marine-plankton communities is as important as their primary production; however, data on the annual carbon retention of marine-plankton communities based on daily sample analysis are limited. Using our published and unpublished data, we calculated the one-year integrated carbon retention of a marine-plankton community at an innermost fixed station in the highly eutrophic Masan Bay, Korea, collected daily from June 2004 to May 2005. The total one-year integrated carbon retention of all plankton taxa in the study period was 471 g C m−3 yr−1. The integrated carbon retentions by phytoplankton, heterotrophic protists, and heterotrophic bacteria were 344, 76, and 40 g C m−3 yr−1, respectively, whereas those by photosynthetic ciliates and metazooplankton were 9 and 2 g C m−3 yr−1, respectively. Among the plankton subgroups, the integrated carbon retention by the phototrophic dinoflagellates (109 g C m−3 yr−1) was highest, followed by raphidophytes (88), cryptophytes (73), diatoms (43), heterotrophic bacteria (40), and heterotrophic dinoflagellates (39). The total duration of the red tides by diatoms that grow using only photosynthesis (42 days), was considerably shorter than that of phototrophic dinoflagellates, raphidophytes, or cryptophytes, which can grow mixotrophically (56–135 days). The shorter duration of red tides by diatoms was primarily responsible for their lower carbon retention, although the maximum growth rates of the diatoms were considerably higher than those of the flagellates. The percentage of the 1-year integrated carbon retention of the heterotrophic protists relative to that of the phytoplankton was approximately 20%, similar to the mean-gross-growth efficiency of heterotrophic-protist grazers on phytoplankton, indicating a good balance between these two components in the planktonic food web. This study reported one-year integrated carbon retention of marine plankton at the species level, calculated based on daily samples, and thus gave an insight into which, and to what extent, species and groups contribute to the total carbon retention of plankton for one year in a highly eutrophic bay. [ABSTRACT FROM AUTHOR]

The isolation of single cells and their further cultivation in confined chambers are essential to the collection of statistically reliable temporal information in cell-based biological experiments. In this work, we present a hydrodynamic single-cell trapping and culturing platform that facilitates biological analysis and experimentation of virus infection into host cells. To find the optimum design of the cell trap at the microscale, we evaluated hook traps with different widths and trap intervals to obtain a high trapping efficiency of a single cell. The proposed design leverages the stochastic position of the cells as they flow into the structured microfluidic channels, where hundreds of single cells are then arrayed in nanoliter chambers for simultaneous cell-specific data collection. Optimum design is used to devise and implement a hydrodynamic cell-trapping mechanism that is minimally detrimental to the cell viability and retains a high trapping efficiency (90%), with the capability of reaching high fill factors (90%) in short loading times (10 min) in a 450-trap device. Finally, we perform an analysis of host-viral interactions under the treatment of a drug concentration gradient as a proof of concept. [ABSTRACT FROM AUTHOR]

In this study, a new heat plate with a groove for butt-welding was developed to investigate the misalignment effects on the joining strengths of polyethylene double walled pipes. Thermal analyses of the material determined the temperature profile of the welding. After the welding, the joining characteristics of the pipes were compared with those welded by the conventional heat plate. The results of the stiffness and flattening tests showed that there were no big differences between the joints made from these two plates. In the leakage test, however, the pipes welded with the conventional heat plate leaked below the required test conditions, while the pipes welded with the grooved heat plate did not show any leakage, even in a range higher than the required conditions. The tensile and bending strength were also improved. The results demonstrated that the grooved heat plate accomplished more complete fusion at the pipe joints and induced high quality joints. [ABSTRACT FROM AUTHOR]

A significant change in the UV-vis absorption of TiO nanorods (NRs) was induced by changing electrondonating stabilizer from oleic acid (OA) to acrylic acid (AcA). When TiO NRs with an average size of 2.5 nm in diameter and 30 nm in length were dispersed in an aqueous AcA solution, a red shift in the optical absorption (0.73 eV at the band edge and 0.55 eV at the onset) was observed. The red shift was attributed to an increase in the electron density inside the TiO NRs. The applicability of the AcA-exchanged TiO NRs for the photocatalyst as well as a UV sensor was evaluated. The AcA-exchanged TiO NRs showed significant photocatalytic activity on the degradation of toluene in the visible light region. Moreover, thin film of the AcA-exchanged TiO NRs on a quartz plate was tested as a UV sensor and it exhibited a good response to a wide range of the UV light. [ABSTRACT FROM AUTHOR]

Depressive failure at the connecting locations between the phenol reactor shell and the stripper tray is one of the primary failure modes in a phenol stripper reactor. The occurrence of cracking failure of an AISI 304 tray in the phenol stripper reactor resulted in an emergency shutdown of the petrochemical plant. Possible causes for the stripper tray cracking were analyzed using a FEM analysis with an ANSYS program and solutions to prevent further cracking failures of the stripper trays are suggested. Variables such as operation pressure and stripper tray thickness were evaluated in terms of safe operation of the phenol production reactor. The simulation results from the ANSYS analysis showed that the stress concentration at the fractured area of the stripper tray could be reduced by a factor of 2 by doubling the thickness of the existing stripper tray. Therefore, for safe and efficient operation of the phenol production line, the design of the stripper should be modified by increasing the thickness of the existing stripper tray. A detailed simulation analysis of the process is discussed. [ABSTRACT FROM AUTHOR]