| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)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. |
- Nadhom, Hama, et al.
(författare)
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Area selective deposition of iron films using temperature sensitive masking materials and plasma electrons as reducing agents
- 2021
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : A V S AMER INST PHYSICS. - 0734-2101 .- 1520-8559. ; 39:4
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Tidskriftsartikel (refereegranskat)abstract
- The potential of area-selective deposition (ASD) with a newly developed chemical vapor deposition (CVD) method, which utilizes plasma electrons as reducing agents for deposition of metal-containing films, is demonstrated using temperature sensitive polymer-based masking materials. The masking materials tested were polydimethylsiloxane, polymethylmethacrylate, polystyrene, parafilm, Kapton tape, Scotch tape, and office paper. The masking materials were all shown to prevent film growth on the masked area of the substrate without being affected by the film deposition process. X-ray photoelectron spectroscopy analysis confirms that the films deposited consist mainly of iron, whereas no film material is found on the masked areas after mask removal. Scanning electron microscopy analysis of films deposited with nonadhesive masking materials show that film growth extended for a small distance underneath the masking material, indicating that the CVD process with plasma electrons as reducing agents is not a line-of-sight deposition technique. The reported methodology introduces an inexpensive and straightforward approach for ASD that opens for exciting new possibilities for robust and less complex area-selective metal-on-metal deposition.
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| 3. |
- Wang, Lei, et al.
(författare)
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Air-Water Interface Assembly of Protein Nanofibrils Promoted by Hydrophobic Additives
- 2021
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 9:28, s. 9289-9299
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Tidskriftsartikel (refereegranskat)abstract
- Herein we demonstrate a novel way of modifying the colloidal stability of proteins by the presence of hydrophobic molecules. A protein capable of self-assembly into protein nanofibrils (PNFs) is milled with a hydrophobic molecular material. Upon dissolution in acidic water followed by heating, the proteins are converted into PNFs containing hydrophobic dyes. When aqueous dispersions of such PNFs are heated, films are formed at the air-water interface. The films contain ordered, optically anisotropic domains, and the shape of the reaction vessel can influence the PNF packing. We demonstrate the generality of the process by employing PNFs derived from the three proteins bovine insulin (INS), beta-lactoglobulin (BLG), and hen egg white lysozyme (HEWL) in combination with the dyes alpha-sexithiophene (6T) and 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM). As individual dye molecules are oriented along the long PNF axis, whole ensembles of dyes become aligned and, as a result, display emission of polarized light. Moreover, in the case of PNFs stained with DCM, stimulated emission is demonstrated.
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| 4. |
- Xu, Weidong, et al.
(författare)
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Iodomethane-Mediated Organometal Halide Perovskite with Record Photoluminescence Lifetime
- 2016
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 8:35, s. 23181-23189
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Tidskriftsartikel (refereegranskat)abstract
- Organometallic lead halide perovskites are excellent light harvesters for high-efficiency photovoltaic devices. However, as the key component in these devices, a perovskite thin film with good morphology and minimal trap states is still difficult to obtain. Herein we show that by incorporating a low boiling point alkyl halide such as iodomethane (CH3I) into the precursor solution, a perovskite (CH3NH3PbI3-xClx) film with improved grain size and orientation can be easily achieved. More importantly, these films exhibit a significantly reduced amount of trap states. Record photoluminescence lifetimes of more than 4 mu s are achieved; these lifetimes are significantly longer than that of pristine CH3NH3PbI3-xClx films. Planar heterojunction solar cells incorporating these CH3I-mediated perovskites have demonstrated a dramatically increased power conversion efficiency compared to the ones using pristine CH3NH3PbI3-xClx. Photoluminescence, transient absorption, and microwave detected photoconductivity measurements all provide consistent evidence that CH3I addition increases the number of excitons generated and their diffusion length, both of which assist efficient carrier transport in the photovoltaic device. The simple incorporation of alkyl halide to enhance perovskite surface passivation introduces an important direction for future progress on high efficiency perovskite optoelectronic devices.
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| 5. |
- Xu, Yalong, et al.
(författare)
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Simultaneously Improved Efficiency and Stability in All-Polymer Solar Cells by a P-i-N Architecture
- 2019
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Ingår i: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 4:9, s. 2277-2286
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Tidskriftsartikel (refereegranskat)abstract
- All-polymer organic solar cells offer exceptional stability. Unfortunately, the use of bulk heterojunction (BHJ) structure has the intrinsic challenge to control the side-chain entanglement and backbone orientation to achieve sophisticated phase separation in all-polymer blends. Here, we revealed that the P-i-N structure can outperform the BHJ ones with a nearly 50% efficiency improvement, reaching a power conversion efficiency approaching 10%. This P-i-N structure can also provide an enhanced internal electric field and remarkably stable morphology Sequential deposition under harsh thermal stress. We have further demonstrated generality of the P-i-N structure in several other all-polymer systems. Considering the adjustable polymer molecular weight and solubility, the P-i-N device structure can be more beneficial for all-polymer systems. With the design of more crystalline polymers, the antiquated P-i-N structure can further show its strength in all-polymer systems by simplified morphology control and improved carrier extraction, becoming a more favorite device structure than the dominant BHJ structure.
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| 6. |
- Yao, Nannan, et al.
(författare)
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In Situ Study the Dynamics of Blade-Coated All-Polymer Bulk Heterojunction Formation and Impact on Photovoltaic Performance of Solar Cells
- 2023
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Ingår i: Solar RRL. - : John Wiley & Sons. - 2367-198X. ; , s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- All-polymer solar cells (all-PSCs) have achieved impressive progress by employing acceptors polymerized from well performing small-molecule non-fullerene acceptors. Herein, the device performance and morphology evolution in blade-coated all-PSCs based on PBDBT:PF5–Y5 blends prepared from two different solvents, chlorobenzene (CB), and ortho-xylene (o-XY) are studied. The absorption spectra in CB solution indicate more ordered conformation for PF5–Y5. The drying process of PBDBT:PF5–Y5 blends is monitored by in situ multifunctional spectroscopy and the final film morphology is characterized with ex situ techniques. Finer-mixed donor/acceptor nanostructures are obtained in CB-cast film than that in o-XY-cast ones, corresponding to more efficient charge generation in the solar cells. More importantly, the conformation of polymers in solution determines the overall film morphology and the device performance. The relatively more ordered structure in CB-cast films is beneficial for charge transport and reduced non-radiative energy loss. Therefore, to achieve high-performance all-PSCs with small energy loss, it is crucial to gain favorable aggregation in the initial stage in solution.
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| 7. |
- Yuan, Yusheng, 1992-
(författare)
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Development of Functionalized Protein Materials
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many proteins are available as side-streams from food production, and in some cases even from industrial waste-streams. This means that proteins are available in large scale and at a relatively low price. As protein are highly complex molecules it is interesting to try to use protein as starting materials in for applications in materials science. Most proteins have the ability to self-assemble into nanofibrils. These fibrils have a regular repeating substructure that consists of β-strands running perpendicular to the fibril axis, resulting in cross-β sheets that run parallel along the fibril axis. The extended β-sheets structure results in the formation of hydrophobic grooves that can act as potential binding sites organic molecules. This means that the functionality of the material may be modified by addition of e.g. light emitting molecules or drug molecules. By such functionalization the protein material may accordingly be suitable for applications such as light-conversion materials (e.g. for use as coatings of light emitting diodes (LEDs)) or for drug-delivery. For such applications, the protein fibrils must be processes into macroscopic structures such as films or gels. Against this background, we employ the food proteins hen egg white lysozyme and β-lactoglobulin as model proteins for fibrillation and functionalization. Through a mechanochemical process the hydrophobic dyes can conveniently be combined with proteins, that can be converted into functionalized protein nanofibrils by liquid-phase self-assembly. By employing protein fibrils functionalized with three dyes, we have been able to form films that enables conversion of UV light to white light (and can thus be employed as a coating on UV-LEDs) with protein fibrils functionalized with multiple dyes. By mixing biodegradable polymers with functionalized protein fibrils, luminescent bioplastic films can be prepared that are processable when wet; a cut film will also self-heal if water is applied. We have also turned functionalized protein fibrils into gel states, including hydrogels or aerogels. In the case of protein fibrils functionalized with Hydantoins (a type of drug molecule) hydrogels were prepared, and the release of the drug was investigated. In addition, aerogels can be prepared from hydrogels by freeze drying, and in this manner lightweight functionalized aerogels are achieved. By functionalization with an electrically conductive polymer, an elastic conductive aerogel is formed that employed as a piezoelectric pressure sensor. In summary a wide range of materials have been prepared suitable for various applications demonstrating the flexibility of the developed functionalization methodology and that the structural richness of protein self-assembly can be employed to prepare a wide variety of types of materials of varying functionality.
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| 8. |
- Yuan, Yusheng, et al.
(författare)
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Mechanochemical Preparation and Self-Assembly of Protein : Dye Hybrids for White Luminescence
- 2021
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Ingår i: ACS Applied Polymer Materials. - : American Chemical Society (ACS). - 2637-6105. ; 3:10, s. 4825-4836
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Tidskriftsartikel (refereegranskat)abstract
- Protein nanofibrils (PNFs) functionalized with multiple dyes are prepared by a combination of mechanochemistry and liquid-phase self-assembly. The three employed dyes are Fluorescent Brightener 378 (F378), 2-butyl-6-(butylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione (Fluorol 555), and Nile red (NR). F378 acts as the donor with Fluorol 555 as the acceptor. F555 in turn acts as the donor and NR as the acceptor. This enables a FRET cascade that enables conversion of UV light to white light. The efficiency of FRET can be influenced by the details of the self-assembly process. If proteins milled with different dyes are mixed prior to self-assembly, nanofibrils are formed containing all three dyes, thus favoring FRET processes. By tuning the ratio of the three luminescent dyes, PNF dispersions are obtained that display bright white light emission. Moreover, the PNF dispersions can be converted into white luminescent films and gels where the PNFs may help to organize dye molecules. Additionally, the PNF materials can be employed as coatings on commercial LEDs, enabling emission of white light.
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| 9. |
- Yuan, Yusheng, et al.
(författare)
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Mechanochemical Preparation of Protein : hydantoin Hybrids and Their Release Properties
- 2022
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Ingår i: ChemSusChem. - : Wiley-VCH Verlag GMBH. - 1864-5631 .- 1864-564X. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- Mechanochemistry is a versatile methodology that can be employed both for covalent bond formation in organic synthesis as well as a mediator to allow preparation novel colloidal dispersions for drug delivery. Herein, ball-milling was employed for the solid-state preparation of fluorescent hydrophobic hydantoins, followed by the unprecedented mechanochemically-mediated complexation of hydrophobic hydantoins within hydrophilic protein beta-lactoglobulin (BLG) and BLG nanofibrils (BLGNFs). These hydantoin:protein materials were in turn incorporated into hydrogels. The effect of incorporation of hydantoins into proteins, as well as the effect of protein structure, on the release properties were then investigated. The conversion of BLG to BLGNFs led to a more sustained release demonstrating that heat treatment of BLG into BLGNFs could be employed to modify release properties. To the best of our knowledge, this is the first example where protein : hydantoin complexes were prepared by mechanochemical methodology and mechanochemistry was combined with self-assembly in order to prepare protein nanomaterials for drug-delivery applications. In addition, the use of the developed protein materials is not limited to delivery of drugs but can for example be employed as components of smart food (delivery of nutrients) or release systems of pesticides.
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| 10. |
- Yuan, Yusheng, et al.
(författare)
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Protein-Based Flexible Conductive Aerogels for Piezoresistive Pressure Sensors
- 2022
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Ingår i: ACS Applied Bio Materials. - : American Chemical Society (ACS). - 2576-6422. ; 5:7, s. 3360-3370
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Tidskriftsartikel (refereegranskat)abstract
- Gelatin is an excellent gelling agent and is widely employed for hydrogel formation. Because of the poor mechanical properties of gelatin when dry, gelatin-aerogels are comparatively rare. Herein we demonstrate that protein nanofibrils can be employed to improve the mechanical properties of gelatin aerogels, and the materials can moreover be functionalized with a an electrically conductive polyelectrolyte resulting in formation of an elastic electrically conductive aerogel that can be employed as a piezoresistive pressure sensor. The aerogel sensor shows a good linear relationship in a wide pressure range (1.8-300 kPa) with a sensitivity of 1.8 kPa(-1). This work presents a convenient way to produce electrically conductive elastic aerogels from low-cost protein precursors.
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