| 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. |
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| 3. |
- Yun, Sang Ho, et al.
(författare)
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Multifunctional silicon inspired by a wing of male Papilio ulysse
- 2012
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 100:3, s. 033109-
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Tidskriftsartikel (refereegranskat)abstract
- Effective entrapment of air and light is a key element for maintaining stable superhydrophobicity and enhancing anti-reflection or absorption. Inspired by a wing of male Papilio ulysse having a unique structure for enabling effective trapping of air and light, we demonstrate that the structure consisting of well-defined multilayer decorated by nanostructures can be obtained on a silicon wafer by a simple microelectromechanical process, consequently resulted in stable superhydrophobocity under static and dynamic conditions, and strong wideband optical absorption.
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| 4. |
- Aulin, Christian, et al.
(författare)
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Design of highly oleophobic cellulose surfaces from structured silicon templates
- 2009
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 1:11, s. 2443-2452
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Tidskriftsartikel (refereegranskat)abstract
- Structured silicon surfaces, possessing hierarchical porous characteristics consisting of micrometer-sized cavities superimposed upon a network of nanometer-sized pillars or wires, have been fabricated by a plasma-etching process. These surfaces have superoleophobic properties, after being coated with fluorinated organic trichlorosilanes, on intrinsically oleophilic surfaces. By comparison with flat silicon surfaces, which are oleophilic, it has been demonstrated that a combination of low surface energy and the structured features of the plasma-etched surface is essential to prevent oil from penetrating the surface cavities and thus induce the observed macroscopic superoleophobic phenomena with very low contact-angle hysteresis and low roll-off angles. The structured silicon surfaces were coated with cellulose nanocrystals using the polyelectrolyte multilayer technique. The cellulose surfaces prepared in this way were then coated with a monolayer of fluorinated trichlorosilanes. These porous cellulose films displayed highly nonwetting properties against a number of liquids with low surface tension, including alkanes such as hexadecane and decane. The wettability and chemical composition of the cellulose/silicon surfaces were characterized with contact-angle goniometry and X-ray photoelectron spectroscopy, respectively. The nano/microtexture features of the cellulose/silicon surfaces were also studied with field-emission scanning electron microscopy. The highly oleophobic structured cellulose surfaces are very interesting model surfaces for the development of biomimetic self-cleaning surfaces in a vast array of products, including green constructions, packaging materials, protection against environmental fouling, sports, and outdoor clothing, and microfluidic systems.
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| 5. |
- Choi, Jae Won, et al.
(författare)
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Interface-driven seebeck effect in two-dimensional trilayer-stacked PtTe2/MoS2/MoS2 heterostructures via electron-electron interactions
- 2023
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Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 115
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional (2D) platinum telluride (PtTe2), which is one of the promising metallic transition metal dichalcogenides, has been proven as an essential candidate for electronic devices, magnetic devices, type-II Dirac fermions, topological superconductors, and other optoelectronic applications. However, the formation and thermal transport as important thermoelectric (TE) device applications have not been realized in large-area 2D PtTe2 films due to their semi-metallic properties. Here, we report an innovative approach to enhance the in-plane TE power factors by piling the metallic PtTe2 films on high-resistance (> 10 MO) intrinsic MoS2 films to form bilayer-PtTe2/MoS2 (5 nm/7 nm)//sapphire and trilayer-PtTe2/MoS2/MoS2 (5 nm/7 nm/7 nm)//sapphire heterostructures via wet-transfer stacking method. Such approaches can be achieved by utilizing 2D/2D heterostructure to increase the electron effective mass due to the strong electron-electron interaction at interface under temperature gradient along the samples and ultimately increase Seebeck coefficients via interface-driven Seebeck effect along with a metallic high-conductivity top-PtTe2 films. The trilayer-stacked PtTe2/MoS2/MoS2 heterostructures exhibit an extremely high Seebeck coefficient of 21.6 mu V/K and power factor of similar to 0.2 mW/m.K-2, which are 231 % and similar to 727 %, higher than those of the metallic 5-nm-thick single PtTe2 film on the sapphire substrate, respectively. Our new physics and observation can pave the way toward an effective strategy for understating 2D/2D TMDC heterostructure materials for high Fig.-of-merit TE energy harvesting devices.
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| 6. |
- Choi, Jae Won, et al.
(författare)
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Observation of a Strong Decoupling Phenomenon in Pt/Si Hybrid Structures for In-Plane Thermoelectric Properties
- 2022
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 126:40, s. 17283-17290
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Tidskriftsartikel (refereegranskat)abstract
- The performance of thermoelectric (TE) materials is limited by the intrinsic coupling of the Seebeck coefficient and the electrical conductivity such that an increase in one leads to a decrease in the other with respect to the carrier concentration. This coupling makes it particularly difficult to enhance the TE power factor in TE materials. In this study, we added a Pt top layer over a silicon wafer, forming a hybridized Pt/Si structure to drive a strong decoupling of the Seebeck coefficient and electrical conductivity. The results show that the electrical resistance in the Pt/Si hybrid structure decreased by ∼94 times compared to that of a single-layer lightly doped Si substrate at 300 K, while the Seebeck coefficient in the hybrid structure decreased slightly compared to that of the single layer. The remarkably high TE performance of the Pt/Si hybrid structure is brought about by the hybridization of the intrinsic high-conductivity Pt layer and the high-Seebeck coefficient Si substrate. In addition, we demonstrate that this novel and effective decoupling method enables the assessment of the in-plane intrinsic Seebeck coefficient of a lightly doped Si wafer, which typically has an electrical resistance that is extremely high to measure the Seebeck coefficient even with a high-resolution voltmeter. These results represent a significant advancement in the understanding of electrical transport in TE materials, which will invigorate further research on Si-based devices for realizing large-area watt-scale TE generation at room temperature.
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| 7. |
- Hormozan, Yashar, et al.
(författare)
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Towards High-Resolution X-Ray Imaging Using a Structured Scintillator
- 2012
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 59:1, s. 19-23
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Tidskriftsartikel (refereegranskat)abstract
- Structured scintillators, by light-guiding secondary emitted visible photons to a pixel in a CCD or CMOS image sensor, improve the lateral resolution of X-ray imaging detectors. In this work we have fabricated pore arrays in a silicon wafer and subsequently filled them with CsI(Tl) by a melting process. The goal was to down-scale the pore geometry for increased resolution. The results show that although pore depth must be reduced to comply with achievable aspect ratio of the Inductively Coupled Plasma (ICP) etching, melting into the pores is possible. The time and temperature has, however, to be optimized to prevent thallium loss during the melting. By correlating light yield measurements with the X-ray absorption in samples of various geometries, we find that the efficiency is slightly reduced for pore diameters approaching one micron. Nevertheless, the increased absorption in deep pores will lead to a significantly improved quantum efficiency compared to thin films currently used to achieve the same lateral resolution.
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| 8. |
- Hwang, K. -H, et al.
(författare)
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Growth of self-template 3D gold nanoparticles on boron nanowire arrays for surface plasmon resonance biosensor application
- 2018
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Ingår i: Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry. - : Elsevier. - 9780128098943 - 9780128097397 ; , s. 460-464
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Enabling detection of target molecules at low concentration is a key feature in localized surface plasmon resonance (LSPR) biosensors, which utilizes the remarkable optical properties of metal nanoparticles such as gold (Au) and silver (Ag) induced by the excitation of LSPR. However, the clear interrelationship between three-dimensional (3D) metal nanoparticle topography and localization of SPR is not fully understood. For the studies, we here propose and demonstrate an approach for fabricating new type of self-template 3D Au nanostructures by using boron nanowire arrays (BNWs) as a building block grown by oxide-assisted vapor-liquid-solid (VLS) mode at relatively low temperatures. This is the first report on formation of 3D Au pores and clusters induced by boron oxide (B2O3) below 500°C.
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| 9. |
- Jeon, So-hyoun, et al.
(författare)
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Selective control of wetting on various substrates
- 2014
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Ingår i: Materials research bulletin. - : Elsevier Ltd. - 0025-5408 .- 1873-4227. ; 58, s. 32-34
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Tidskriftsartikel (refereegranskat)abstract
- Selective control of wetting is highly demanded for a broad window of applications. To selectively control wetting a surface should be locally modified by structuring surfaces or modulating surface chemistry. However, the local modifications are still challenging due to their complex and expensive processes. In this report we demonstrate the development of a facile approach for selective control of wetting on various substrates. Taking superhydrophobic polypropylene particles and hydrophilic silica nanoparticles, we here show that the locally controlled wetting can be achieved by coating the particles on a wide range of substrates including metal and paper and be applied to microfluidic channels. Furthermore, we represent that the coating method can be applied to any surfaces regardless of compositions and geometries.
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| 10. |
- Kanoni, Stavroula, et al.
(författare)
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Implicating genes, pleiotropy, and sexual dimorphism at blood lipid loci through multi-ancestry meta-analysis.
- 2022
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Ingår i: Genome biology. - : Springer Science and Business Media LLC. - 1474-760X .- 1465-6906 .- 1474-7596. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- Genetic variants within nearly 1000 loci are known to contribute to modulation of blood lipid levels. However, the biological pathways underlying these associations are frequently unknown, limiting understanding of these findings and hindering downstream translational efforts such as drug target discovery.To expand our understanding of the underlying biological pathways and mechanisms controlling blood lipid levels, we leverage a large multi-ancestry meta-analysis (N=1,654,960) of blood lipids to prioritize putative causal genes for 2286 lipid associations using six gene prediction approaches. Using phenome-wide association (PheWAS) scans, we identify relationships of genetically predicted lipid levels to other diseases and conditions. We confirm known pleiotropic associations with cardiovascular phenotypes and determine novel associations, notably with cholelithiasis risk. We perform sex-stratified GWAS meta-analysis of lipid levels and show that 3-5% of autosomal lipid-associated loci demonstrate sex-biased effects. Finally, we report 21 novel lipid loci identified on the X chromosome. Many of the sex-biased autosomal and X chromosome lipid loci show pleiotropic associations with sex hormones, emphasizing the role of hormone regulation in lipid metabolism.Taken together, our findings provide insights into the biological mechanisms through which associated variants lead to altered lipid levels and potentially cardiovascular disease risk.
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