| 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. |
- Zhang, Guojie, et al.
(författare)
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Comparative genomics reveals insights into avian genome evolution and adaptation
- 2014
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 346:6215, s. 1311-1320
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Tidskriftsartikel (refereegranskat)abstract
- Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits.
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| 3. |
- Liu, Cunming, et al.
(författare)
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Asynchronous Photoexcited Electronic and Structural Relaxation in Lead-Free Perovskites
- 2019
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 141:33, s. 13074-13080
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Tidskriftsartikel (refereegranskat)abstract
- Vacancy-ordered lead-free perovskites with more-stable crystalline structures have been intensively explored as the alternatives for resolving the toxic and long-term stability issues of lead halide perovskites (LHPs). The dispersive energy bands produced by the closely packed halide octahedral sublattice in these perovskites are meanwhile anticipated to facility the mobility of charge carriers. However, these perovskites suffer from unexpectedly poor charge carrier transport. To tackle this issue, we have employed the ultrafast, elemental-specific X-ray transient absorption (XTA) spectroscopy to directly probe the photoexcited electronic and structural dynamics of a prototypical vacancy-ordered lead-free perovskite (Cs3Bi2Br9). We have discovered that the photogenerated holes quickly self-trapped at Br centers, simultaneously distorting the local lattice structure, likely forming small polarons in the configuration of Vk center (Br2 - dimer). More significantly, we have found a surprisingly long-lived, structural distorted state with a lifetime of ∼59 μs, which is ∼3 orders of magnitude slower than that of the charge carrier recombination. Such long-lived structural distortion may produce a transient "background" under continuous light illumination, influencing the charge carrier transport along the lattice framework. ©
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| 4. |
- Wang, Yingqi, et al.
(författare)
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Visualizing Light-Induced Microstrain and Phase Transition in Lead-Free Perovskites Using Time-Resolved X-Ray Diffraction
- 2022
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 144:12, s. 5335-5341
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Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskites have emerged as promising materials for optoelectronic applications in the last decade. A large amount of effort has been made to investigate the interplay between the crystalline lattice and photoexcited charge carriers as it is vital to their optoelectronic performance. Among them, ultrafast laser spectroscopy has been intensively utilized to explore the charge carrier dynamics of perovskites, from which the local structural information can only be extracted indirectly. Here, we have applied a time-resolved X-ray diffraction technique to investigate the structural dynamics of prototypical two-dimensional lead-free halide perovskite Cs3Bi2Br9nanoparticles across temporal scales from 80 ps to microseconds. We observed a quick recoverable (a few ns) photoinduced microstrain up to 0.15% and a long existing lattice expansion (∼a few hundred nanoseconds) at mild laser fluence. Once the laser flux exceeds 1.4 mJ/cm2, the microstrain saturates and the crystalline phase partially transfers into a disordered phase. This photoinduced transient structural change can recover within the nanosecond time scale. These results indicate that photoexcitation of charge carriers couples with lattice distortion, which fundamentally affects the dielectric environment and charge carrier transport.
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| 5. |
- Zhang, Xingxing, et al.
(författare)
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Smart meter and in-home display for energy savings in residential buildings : a pilot investigation in Shanghai, China
- 2019
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Ingår i: Intelligent Buildings International. - : Taylor & Francis. - 1750-8975 .- 1756-6932. ; 11:1, s. 4-26
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Tidskriftsartikel (refereegranskat)abstract
- Smart meters and in-home displays (IHDs) have been recently adopted to help give residential users more control over energy consumption, and meet environmental and supply security objectives. The article aims to identify the effectiveness and potential of smart meters and real-time IHDs in reducing Shanghai household energy consumption by affecting occupants? behaviour. A general landscape of the occupant behaviour in residential buildings was briefly painted. A pilot study in Shanghai with an effective sample of 131 respondents was arranged into two groups as IHD and non-IHD households. A dedicated statistical analysis model was developed based on the micro-level empirical data to investigate the characteristics and the regulations of electricity consumption in these two groups, such as check frequency, electricity consumption reduction and shifting, energy bill saving, and standby power. The research results demonstrate that IHDs could lead to around 9.1% reduction in monthly electricity consumption and about 11.0% cut off in monthly electricity bills. A general comparison of the electricity consumption reduction between this research and the average UK case was further made. Barriers at current stage and challenges for further work were finally discussed. The statistical model is expected to ?future proof? smart meter and real-time displays through macro-level designing in modularity and flexibility in China. The overall research initially proves the concept of the feasible impact of smart meter and display technologies in the Chinese context, which is further expected to contribute to the empirical evidence on how IHD feedback could influence household electricity consumption in the Chinese context.
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