| 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. |
- Shao, Xue-Feng, et al.
(författare)
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Screening of sugar alcohols and their binary eutectic mixtures as phase change materials for low-to-medium temperature thermal energy storage. (II) : Isothermal melting and crystallization behaviors
- 2019
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 180, s. 572-583
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Tidskriftsartikel (refereegranskat)abstract
- Based on the non-isothermal phase change behaviors of twenty-one pure and mixture sugar alcohols presented in our previous study (Part 1), the isothermal melting and crystallization behaviors were further tested in this supplemental work for five selected pure sugar alcohols (xylitol, erythritol, dmannitol, d-dulcitol and inositol) and their five binary eutectic mixtures to make an advanced screening of these candidates for low-to-medium temperature latent heat storage. The isothermal melting and crystallization behaviors of these ten candidates were tested at a constant degree of superheat (10 degrees C) and various degrees of subcooling up to 210 degrees C. The phase change temperatures, degrees of supercooling and durations of phase change were determined by the recorded temperature-history curves. It was found that the incrystallizable xylitol and its eutectic mixture of xylitol (75 mol%) + erythritol with low melting points under 100 degrees C are also unable to crystallize during isothermal cool-down at any degrees of subcooling (30-90 degrees C) due to the unavailability to nucleation. The rest eight crystallizable candidates all suffer from severe supercooling and are unable to crystallize at low degrees of subcooling (<20 degrees C). They undergo both one-phase supercooling due to poor nucleation performance and two-phase supercooling, which was unable to be obtained previously by non-isothermal cooling, due to slow crystallization kinetics. However, it seems difficult to find a correlation between the observed degrees of supercooling in both the liquid and solid phases and the prescribed degrees of subcooling by only three consecutive isothermal melting and crystallization cycles, as a result of the randomness of nucleation and large size of samples. The duration of crystallization was shown to decrease with increasing the degree of subcooling for both pure and mixture sugar alcohols due to the enhanced driving force for crystallization. The durations of crystallization of the mixture sugar alcohols appear to be longer than those of their pure compounds, due to the lower thermal conductivity and higher dynamic viscosity of the mixtures. Combining the present isothermal and the previous non-isothermal test results, it has been confirmed that the difficulty in crystallization and the severe supercooling are the primary issues for sugar alcohols, which must be addressed before they can be used in real-world latent heat storage systems.
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| 3. |
- Brownstein, Catherine A., et al.
(författare)
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An international effort towards developing standards for best practices in analysis, interpretation and reporting of clinical genome sequencing results in the CLARITY Challenge
- 2014
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Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X. ; 15:3, s. R53-
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is tremendous potential for genome sequencing to improve clinical diagnosis and care once it becomes routinely accessible, but this will require formalizing research methods into clinical best practices in the areas of sequence data generation, analysis, interpretation and reporting. The CLARITY Challenge was designed to spur convergence in methods for diagnosing genetic disease starting from clinical case history and genome sequencing data. DNA samples were obtained from three families with heritable genetic disorders and genomic sequence data were donated by sequencing platform vendors. The challenge was to analyze and interpret these data with the goals of identifying disease-causing variants and reporting the findings in a clinically useful format. Participating contestant groups were solicited broadly, and an independent panel of judges evaluated their performance. Results: A total of 30 international groups were engaged. The entries reveal a general convergence of practices on most elements of the analysis and interpretation process. However, even given this commonality of approach, only two groups identified the consensus candidate variants in all disease cases, demonstrating a need for consistent fine-tuning of the generally accepted methods. There was greater diversity of the final clinical report content and in the patient consenting process, demonstrating that these areas require additional exploration and standardization. Conclusions: The CLARITY Challenge provides a comprehensive assessment of current practices for using genome sequencing to diagnose and report genetic diseases. There is remarkable convergence in bioinformatic techniques, but medical interpretation and reporting are areas that require further development by many groups.
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| 4. |
- Wang, Mei, et al.
(författare)
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Visible-light-absorbing semiconductor/molecular catalyst hybrid photoelectrodes for H-2 or O-2 evolution : recent advances and challenges
- 2017
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Ingår i: Sustainable Energy & Fuels. - : ROYAL SOC CHEMISTRY. - 2398-4902. ; 1:8, s. 1641-1663
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Forskningsöversikt (refereegranskat)abstract
- The research on the conversion of solar energy and its storage as an eco-friendly and momentarily available chemical fuel, such as H-2, by sunlight-driven water splitting is closely related to the sustainable development of the global economy and to the continuous improvement of the modern living standards of human beings. One of the most promising approaches to sunlight-driven water splitting is to construct a dual-illuminated photoelectrochemical (PEC) cell by integrating a photoanode with a photocathode in a tandem configuration. To this end, the important work is to individually develop highly efficient, durable, inexpensive, and readily scalable photoanodes and photocathodes for each half reaction of water splitting, either O-2 or H-2 evolution reaction (OER or HER). A promising approach emerging in recent years towards OER photoanodes and HER photocathodes is the immobilization of molecular catalysts (MC) onto the surface of visible-light-absorbing semiconductor (VLASC) electrodes. Very recently, some encouraging results have been achieved in the construction of MC-modified VLASC photoanodes and photocathodes. This review is focused on the recent advances in hybrid photoelectrodes for OER and HER, which were built by the integration of MCs with VLASC materials. After a brief introduction of three major units, viz. VLASC materials, MCs, and anchor groups, used to date for fabricating hybrid photoelectrodes for OER and HER, the construction strategy and the performance of the VLASC/MC photoanodes and photocathodes are described in two respective chapters. Finally, challenges and developments in future studies of VLASC/MC hybrid photoelectrodes are discussed.
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| 5. |
- Zhang, Peili, et al.
(författare)
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Gas-templating of hierarchically structured Ni-Co-P for efficient electrocatalytic hydrogen evolution
- 2017
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 5:16, s. 7564-7570
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Tidskriftsartikel (refereegranskat)abstract
- One of the grand challenges for developing scalable and sustainable hydrogen producing systems is the lack of efficient and robust earth-abundant element based catalysts for the hydrogen evolution reaction (HER). Herein, a hierarchically structured Ni-Co-P film was fabricated via a gas templating electro-deposition method. This film exhibits remarkably high catalytic performance for the HER in 1 M KOH with respective current densities of -10 and -500 mA cm(-2) at the overpotentials of -30 and -185 mV with a Tafel slope of 41 mV dec(-1). A controlled potential electrolysis experiment demonstrates that the as-prepared Ni-Co-P film is an efficient and robust catalyst with a faradaic efficiency close to 100%. Systematic characterization suggests that the unique hierarchical structure and the mutual participation of nano-sized Ni/Co based components are responsible for the high HER catalytic activity.
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| 6. |
- Zhao, Guang-Jiu, et al.
(författare)
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Photoinduced intramolecular charge transfer and S-2 fluorescence in thiophene-pi-conjugated donor-acceptor systems : Experimental and TDDFT studies
- 2008
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 14:23, s. 6935-6947
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Tidskriftsartikel (refereegranskat)abstract
- Experimental and theoretical methods were used to study newly synthesized thiophene-pi-cojugated donor-acceptor compounds, which were found to exhibit efficient intramolecular charge-transfer emission in polar solvents with relatively large Stokes shifts and strong solvatochromism. To gain insight into the solvatochromic behavior of these compounds, the dependence of the spectra on solvent polarity was studied on the basis of Lippert-Mataga models. We found that intramolecular charge transfer in these donor-acceptor systems is significantly dependent on the electron-with-drawing substituents at the thienyl 2-position. The dependence of the absorption and emission spectra of these compounds in methanol on the concentration of trifluoroacetic acid was used to confirm intramolecular charge-tranfer emission. Moreover, the calculated absorption and emission energies, which are in accordance with the experimental values, suggested that fluorescence can be emitted from different geometric confirmations. In addition, a novel S-2 fluorescence phenomenon for some of these compounds was also be observed. The fluorescence excitation spectra were used to confirm the S-2 fluorescence. We demonstrate that S-2 fluorescence can be explained by the calculated energy gap between the S-2 and S-1 states of these molecules. Furthermore, nonlinear optical behavior of the thiophene-pi-conjugated compound with diethylcyanomethylphosphonate substituents was predicted in theory.
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