| 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. |
- Fan, Bo, et al.
(författare)
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A Review of Current-Limiting Control of Grid-Forming Inverters Under Symmetrical Disturbances
- 2022
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Ingår i: IEEE OPEN JOURNAL OF POWER ELECTRONICS. - : Institute of Electrical and Electronics Engineers (IEEE). - 2644-1314. ; 3, s. 955-969
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Forskningsöversikt (refereegranskat)abstract
- Grid-forming (GFM) inverters are recognized as a viable solution to increase the penetration of renewable energy in bulk power systems. However, they are physically different from synchronous generators in terms of overcurrent capability. To protect the power semiconductor devices and support the power grid under severe symmetrical disturbances, the GFM control systems should be able to achieve the following requirements: current magnitude limitation, fault current contribution, and fault recovery capability. Various current-limiting control methods are reported in the literature to fulfill these goals, including current limiters, virtual impedance, and voltage limiters. This paper presents an overview of those methods. Emerging challenges that need to be addressed, including temporary overcurrent, unspecified output current vector angle, undesired current saturation, and transient overvoltage, are pointed out. Comparative simulations are conducted to demonstrate the performance of different methods under grid voltage drops and phase jumps. Finally, open issues of current-limiting control methods for GFM inverters, including transient stability assessment, voltage source behavior under overcurrent conditions, and windup of voltage controllers, are shared.
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| 3. |
- Fan, Jin, et al.
(författare)
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Design of Ultra-Wideband Phased Array Feed for Radio Telescope
- 2020
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Ingår i: 2020 33rd General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2020.
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Konferensbidrag (refereegranskat)abstract
- This paper presents an ultra-wideband Phased Array Feed (PAF) based on novel flat bend crossed dipole fed by 50Ohm coaxial line. The PAF is dual-polarized and made from all-metal to minimize Ohmic losses and simplify cryogenic integration. It is optimized for 1-2 GHz band and can be good PAF candidate for the Five hundred meter Aperture Spherical Telescope (FAST) and Qi Tai Telescope (QTT) as well as other radio telescopes.
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| 4. |
- Fan, Jin, et al.
(författare)
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Development of wideband orthomode transducers for FAST cryogenic receiver system
- 2020
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Ingår i: Research in Astronomy and Astrophysics. - : IOP Publishing. - 1674-4527. ; 20:5
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the design, construction, and performance of the wideband orthomode transducers (OMTs) for the L- (1.2-1.8 GHz), the S- (2-3 GHz) and the P- (0.56-1.12 GHz) band receiver systems of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). These OMTs operate at the cryogenic temperature of 70K to reduce their thermal noise contribution to the receiver chains. The development on the FAST L- and S-band quad-ridged waveguide (QRWG) OMTs is carried out based on the theoretical mode analysis. In view of the miniaturization of FAST cryogenic receiver system at P-band, a novel wideband compact bowtie dipole OMT is designed with an octave bandwidth as well as a length of only quarter wavelength. The proposed L-, S- and P-band OMTs are designed and optimized by using Ansys High Frequency Structure Simulator (HFSS), and then manufactured, tested at room temperature. Measurement of FAST cryogenic receiver system noise is also performed with the L-, S- and P-band OMTs installed. The measured results fully comply with the design specifications.
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| 5. |
- Fan, Lichao, et al.
(författare)
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Active metabolic pathways of anaerobic methane oxidation in paddy soils
- 2021
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 156
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic oxidation of methane (AOM) is a globally important CH4 sink. However, the AOM pathways in paddy soils, the largest agricultural source of methane emissions (31 Mio tons per year) are not yet well described. Here, a combination of C-13 isotope tracer, phospholipid fatty acids (PLFA) analyses, and microbial community analysis was used to identify AOM pathways in fertilized (pig manure, biochar, NPK, and the control) paddy soils amended with alternative electron acceptors (AEAs) (NO3-, Fe3+, SO42-, humic acids, and the reference without AEAs addition). After 84 days of anaerobic incubation, the microbial co-occurrence network got tightened and became more complex relative to unincubated samples. Fertilization and AEAs addition led to a strong divergence of the microbial community structure as indicated by abundances of AOM-related microbiota and C-13 incorporation into microbial PLFA, thus suggesting an environmental niche differentiation of AOM-involved microorganisms. Comparative analyses revealed a set of major and minor AOM pathways with synergistic relations to complementary anaerobic microbial groups. NO3--driven AOM, performed by members of the candidate group ANME-2d, was the major AOM pathway. Minor AOM pathways involved NO2- reduction by NC10, reduction of humic acids and Fe3+ by Geobacter species, and SO42- reduction by sulfate-reducing bacteria linked with anaerobic methanotrophs. As identified by the network analysis, these active AOM pathways compensated a fraction of CH4 produced during ongoing methanogenesis. From a broader ecological perspective, nitrogendriven AOM will become a more important methane sink in the future with the increases of nitrogen fertilization and deposition.
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| 6. |
- Huang, Hui-Ling, et al.
(författare)
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ThermalProGAN : a sequence-based thermally stable protein generator trained using unpaired data
- 2023
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Ingår i: Journal of Bioinformatics and Computational Biology. - : World Scientific. - 0219-7200 .- 1757-6334. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Motivation: The synthesis of proteins with novel desired properties is challenging but sought after by the industry and academia. The dominating approach is based on trial-and-error inducing point mutations, assisted by structural information or predictive models built with paired data that are difficult to collect. This study proposes a sequence-based unpaired-sample of novel protein inventor (SUNI) to build ThermalProGAN for generating thermally stable proteins based on sequence information.Results: The ThermalProGAN can strongly mutate the input sequence with a median number of 32 residues. A known normal protein, 1RG0, was used to generate a thermally stable form by mutating 51 residues. After superimposing the two structures, high similarity is shown, indicating that the basic function would be conserved. Eighty four molecular dynamics simulation results of 1RG0 and the COVID-19 vaccine candidates with a total simulation time of 840ns indicate that the thermal stability increased.Conclusion: This proof of concept demonstrated that transfer of a desired protein property from one set of proteins is feasible.
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| 7. |
- Liu, Yanfeng, et al.
(författare)
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In Situ Optical Spectroscopy Demonstrates the Effect of Solvent Additive in the Formation of All-Polymer Solar Cells
- 2022
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 13:50, s. 11696-11702
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Tidskriftsartikel (refereegranskat)abstract
- 1-Chloronaphthalene (CN) has been a common solvent additive in both fullerene- A nd nonfullerene-based organic solar cells. In spite of this, its working mechanism is seldom investigated, in particular, during the drying process of bulk heterojunctions composed of a donor:acceptor mixture. In this work, the role of CN in all-polymer solar cells is investigated by in situ spectroscopies and ex situ characterization of blade-coated PBDB-T:PF5-Y5 blends. Our results suggest that the added CN promotes self-aggregation of polymer donor PBDB-T during the drying process of the blend film, resulting in enhanced crystallinity and hole mobility, which contribute to the increased fill factor and improved performance of PBDB-T:PF5-Y5 solar cells. Besides, the nonradiative energy loss of the corresponding device is also reduced by the addition of CN, corresponding to a slightly increased open-circuit voltage. Overall, our observations deepen our understanding of the drying dynamics, which may guide further development of all-polymer solar cells.
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| 8. |
- Luo, Zhenghui, et al.
(författare)
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Heteroheptacene-based acceptors with thieno[3,2-b]pyrrole yield high-performance polymer solar cells
- 2022
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Ingår i: NATIONAL SCIENCE REVIEW. - : Oxford University Press. - 2095-5138 .- 2053-714X. ; 9:7
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Tidskriftsartikel (refereegranskat)abstract
- Rationally utilizing and developing synthetic units is of particular significance for the design of high-performance non-fullerene small-molecule acceptors (SMAs). Here, a thieno[3,2-b]pyrrole synthetic unit was employed to develop a set of SMAs (ThPy1, ThPy2, ThPy3 and ThPy4) by changing the number or the position of the pyrrole ring in the central core based on a standard SMA of IT-4Cl, compared to which the four thieno[3,2-b]pyrrole-based acceptors exhibit bathochromic absorption and upshifted frontier orbital energy level due to the strong electron-donating ability of pyrrole. As a result, the polymer solar cells (PSCs) of the four thieno[3,2-b]pyrrole-based acceptors yield higher open-circuit voltage and lower energy loss relative to those of the IT-4Cl-based device. What is more, the ThPy3-based device achieves a power conversion efficiency (PCE) (15.3%) and an outstanding fill factor (FF) (0.771) that are superior to the IT-4Cl-based device (PCE = 12.6%, FF = 0.758). The ThPy4-based device realizes the lowest energy loss and the smallest optical band gap, and the ternary PSC device based on PM6:BTP-eC9:ThPy4 exhibits a PCE of 18.43% and a FF of 0.802. Overall, this work sheds light on the great potential of thieno[3,2-b]pyrrole-based SMAs in realizing low energy loss and high PCE. Four heteroheptacene-based acceptors using thieno[3,2-b]pyrrole building block were developed for the first time, and all the four acceptors-based devices realized high performance and low energy loss.
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| 9. |
- Nie, Huizhen, et al.
(författare)
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The short isoform of PRLR suppresses the pentose phosphate pathway and nucleotide synthesis through the NEK9-Hippo axis in pancreatic cancer
- 2021
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Ingår i: Theranostics. - : Ivyspring International Publisher. - 1838-7640. ; 11:8, s. 3898-3915
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Tidskriftsartikel (refereegranskat)abstract
- Prolactin binding to the prolactin receptor exerts pleiotropic biological effects in vertebrates. The prolactin receptor (PRLR) has multiple isoforms due to alternative splicing. The biological roles and related signaling of the long isoform (PRLR-LF) have been fully elucidated. However, little is known about the short isoform (PRLR-SF), particularly in cancer development and metabolic reprogramming, a core hallmark of cancer. Here, we reveal the role and underlying mechanism of PRLR-SF in pancreatic ductal adenocarcinoma (PDAC). Methods: A human PDAC tissue array was used to investigate the clinical relevance of PRLR in PDAC. The in vivo implications of PRLR-SF in PDAC were examined in a subcutaneous xenograft model and an orthotopic xenograft model. Immunohistochemistry was performed on tumor tissue obtained from genetically engineered KPC (KrasG12D/+; Trp53R172H/+; Pdx1-Cre) mice with spontaneous tumors. 13C-labeled metabolite measures, LC-MS, EdU incorporation assays and seahorse analyses were used to identify the effects of PRLR-SF on the pentose phosphate pathway and glycolysis. We identified the molecular mechanisms by immunofluorescence, coimmunoprecipitation, proximity ligation assays, chromatin immunoprecipitation and promoter luciferase activity. Public databases (TCGA, GEO and GTEx) were used to analyze the expression and survival correlations of the related genes. Results: We demonstrated that PRLR-SF is predominantly expressed in spontaneously forming pancreatic tumors of genetically engineered KPC mice and human PDAC cell lines. PRLR-SF inhibits the proliferation of PDAC cells (AsPC-1 and BxPC-3) in vitro and tumor growth in vivo. We showed that PRLR-SF reduces the expression of genes in the pentose phosphate pathway (PPP) and nucleotide biosynthesis by activating Hippo signaling. TEAD1, a downstream transcription factor of Hippo signaling, directly regulates the expression of G6PD and TKT, which are PPP rate-limiting enzymes. Moreover, NEK9 directly interacts with PRLR-SF and is the intermediator between PRLR and the Hippo pathway. The PRLR expression level is negatively correlated with overall survival and TNM stage in PDAC patients. Additionally, pregnancy and lactation increase the ratio of PRLR-SF:PRLR-LF in the pancreas of wild-type mice and subcutaneous PDAC xenograft tumors. Conclusion: Our characterization of the relationship between PRLR-SF signaling, the NEK9-Hippo pathway, PPP and nucleotide synthesis explains a mechanism for the correlation between PRLR-SF and metabolic reprogramming in PDAC progression. Strategies to alter this pathway might be developed for the treatment or prevention of pancreatic cancer.
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| 10. |
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The Seventeenth Data Release of the Sloan Digital Sky Surveys : Complete Release of MaNGA, MaStar, and APOGEE-2 Data
- 2022
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics (IOP). - 0067-0049 .- 1538-4365. ; 259:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 survey that publicly releases infrared spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey subsurvey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated value-added catalogs. This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper, Local Volume Mapper, and Black Hole Mapper surveys.
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| 11. |
- Yang, Heng, et al.
(författare)
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Relationship between hydroclimatic variables and reservoir wetland landscape pattern indices : A case study of the Sanmenxia Reservoir wetland on the Yellow River, China
- 2020
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Ingår i: Journal of Earth System Science. - : Springer Science and Business Media LLC. - 0973-774X .- 2347-4327. ; 129:1
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Tidskriftsartikel (refereegranskat)abstract
- Reservoir construction has led to the development of numerous wetlands, and these wetlands play an important role in global environmental change. In this paper, we investigate the relationship between reservoir wetlands and hydroclimatic variables. We used the MODIS land cover product to extract the wetland area of the Sanmenxia Reservoir, China. Then, various indices of reservoir wetland landscape patterns were calculated. Principal component analysis was performed to build the Sanmenxia Reservoir wetland comprehensive landscape pattern index (CLPI) to depict the changes in Sanmenxia Reservoir wetlands from 2001 to 2013. Pearson correlation analysis was used to assess their relationship. The following results were obtained. Firstly, the Sanmenxia Reservoir wetland area considerably declined and the landscape heterogeneity decreased from 2001 to 2013, especially in 2004. Secondly, the CLPI is significantly negatively correlated with annual runoff and significantly positively correlated with annual sediment discharge, annual average water level and annual shallow groundwater table in Sanmenxia Reservoir regions. Additionally, due to the decline in the reservoir wetland area, the values of Shannon's diversity index and Simpson's diversity index decreased in the study area. Therefore, the study suggests that maintaining a stable and healthy reservoir wetland area should be the focus of ecological reservoir management.
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| 12. |
- 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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| 13. |
- Zhao, Fangzhou, et al.
(författare)
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Closed-Form Solutions for Grid-Forming Converters : A Design-Oriented Study
- 2024
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Ingår i: IEEE OPEN JOURNAL OF POWER ELECTRONICS. - : Institute of Electrical and Electronics Engineers (IEEE). - 2644-1314. ; 5, s. 186-200
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Tidskriftsartikel (refereegranskat)abstract
- This paper derives closed-form solutions for grid-forming converters with power synchronization control (PSC) by subtly simplifying and factorizing the complex closed-loop models. The solutions can offer clear analytical insights into control-loop interactions, enabling guidelines for robust controller design. It is proved that 1) the proportional gains of PSC and alternating voltage control (AVC) can introduce negative resistance, which aggravates synchronous resonance (SR) of power control, 2) the integral gain of AVC is the cause of sub-synchronous resonance (SSR) in stiff-grid interconnections, albeit the proportional gain of AVC can help dampen the SSR, and 3) surprisingly, the current controller that dampens SR actually exacerbates SSR. Controller design guidelines are given based on analytical insights. The findings are verified by simulations and experimental results.
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