| 1. |
- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Han, Lu, et al.
(author)
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Crystal twinning of bicontinuous cubic structures
- 2020
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In: IUCrJ. - 2052-2525. ; 7, s. 228-237
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Journal article (peer-reviewed)abstract
- Bicontinuous cubic structures in soft matter consist of two intertwining labyrinths separated by a partitioning layer. Combining experiments, numerical modelling and techniques in differential geometry, we investigate twinning defects in bicontinuous cubic structures. We first demonstrate that a twin boundary is most likely to occur at a plane that cuts the partitioning layer almost perpendicularly, so that the perturbation caused by twinning remains minimal. This principle can be used as a criterion to identify potential twin boundaries, as demonstrated through detailed investigations of mesoporous silica crystals characterized by diamond and gyroid surfaces. We then discuss that a twin boundary can result from a stacking fault in the arrangement of inter-lamellar attachments at an early stage of structure formation. It is further shown that enhanced curvature fluctuations near the twin boundary would cost energy because of geometrical frustration, which would be eased by a crystal distortion that is experimentally observed.
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| 3. |
- Han, Yuanyuan, et al.
(author)
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Flexible conductive silk-PPy hydrogel toward wearable electronic strain sensors
- 2022
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In: Biomedical Materials. - : IOP Publishing Ltd. - 1748-6041 .- 1748-605X. ; 17:2
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Journal article (peer-reviewed)abstract
- Conductive hydrogels have been studied as promising materials for the flexible and wearable bioelectronics, because of their unique electrical and mechanical properties. Addition of conducting polymers in biomaterial-based hydrogel matrix is a simple yet effective way to construct hydrogels with good conductivity and flexibility. In this work, a conductive hydrogel composed by a silk hydrogel and a conducting polymer, polypyrrole (PPy), is developed via in situ polymerization of pyrrole into the silk fibroin network. The silk-PPy hydrogel shows high conductivity (26 S m(-1)), as well as sensitive and fast responses to corresponding conformation changes. Taking advantages of these properties, flexible and wearable strain sensors are proposed for the monitoring of various body movements, which can detect both the large and subtle human motions with good sensitivity, reproducibility and stability. The hybridization of biomaterials and conducting polymers endows the multifunctions of the conductive hydrogels, thus showing considerable potentials in the advancement of the wearable electronics.
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| 4. |
- Wang, Binmin, et al.
(author)
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Multifunctional Underwater Adhesive Film Enabled by a Single-Component Poly(ionic liquid)
- 2023
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In: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:6, s. 5871-5879
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Journal article (peer-reviewed)abstract
- Tremendous efforts have been devoted to exploiting synthetic wet adhesives for real-life applications. However, developing low-cost, robust, and multifunctional wet adhesive materials remains a considerable challenge. Herein, a wet adhesive composed of a single-component poly(ionic liquid) (PIL) that enables fast and robust underwater adhesion is reported. The PIL adhesive film possesses excellent stretchability and flexibility, enabling its anchoring on target substrates regardless of deformation and water scouring. Surface force measurements show the PIL can achieve a maximum adhesion of 56.7 mN·m–1 on diverse substrates (both hydrophilic and hydrophobic substrates) in aqueous media, within ∼30 s after being applied. The adhesion mechanisms of the PIL were revealed via the force measurements, and its robust wet adhesive capacity was ascribed to the synergy of different non-covalent interactions, such as of hydrogen bonding, cation−π, electrostatic, and van der Waals interactions. Surprisingly, this PIL adhesive film exhibited impressive underwater sound absorption capacity. The absorption coefficient of a 0.7 mm-thick PIL film to 4–30 kHz sound waves could be as high as 0.80–0.92. This work reports a multifunctional PIL wet adhesive that has promising applications in many areas and provides deep insights into interfacial interaction mechanisms underlying the wet adhesion capability of PILs.
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