| 1. |
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| 2. |
- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)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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| 3. |
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- 2019
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Journal article (peer-reviewed)
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| 4. |
- Klionsky, Daniel J., et al.
(author)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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In: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Research review (peer-reviewed)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Li, Qianqian, et al.
(author)
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Effect of an upstream unconnected bulge on film cooling
- 2017
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In: Chemical Engineering Transactions. - 1974-9791. ; 61, s. 223-228
-
Journal article (peer-reviewed)abstract
- Film cooling technology is commonly used in a cooling system of gas turbines. For different upstream bulge configurations, the unconnected and connected configurations were used to investigate the film cooling effectiveness and downstream dimensionless temperature distributions in this paper. Moreover, the effect of the blowing ratio was analyzed by using the computational fluid mechanics. The results show that a bulge configuration located upstream the film hole shows more uniform film cooling effectiveness, resulting in an enhancement of the lateral cooling effectiveness. The film cooling effectiveness for the unconnected bulge configuration slightly decreases along the centerline.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Banin, U., et al.
(author)
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Nanotechnology for catalysis and solar energy conversion
- 2021
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In: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 32:4
-
Journal article (peer-reviewed)abstract
- This roadmap on Nanotechnology for Catalysis and Solar Energy Conversion focuses on the application of nanotechnology in addressing the current challenges of energy conversion: 'high efficiency, stability, safety, and the potential for low-cost/scalable manufacturing' to quote from the contributed article by Nathan Lewis. This roadmap focuses on solar-to-fuel conversion, solar water splitting, solar photovoltaics and bio-catalysis. It includes dye-sensitized solar cells (DSSCs), perovskite solar cells, and organic photovoltaics. Smart engineering of colloidal quantum materials and nanostructured electrodes will improve solar-to-fuel conversion efficiency, as described in the articles by Waiskopf and Banin and Meyer. Semiconductor nanoparticles will also improve solar energy conversion efficiency, as discussed by Boschloo et al in their article on DSSCs. Perovskite solar cells have advanced rapidly in recent years, including new ideas on 2D and 3D hybrid halide perovskites, as described by Spanopoulos et al 'Next generation' solar cells using multiple exciton generation (MEG) from hot carriers, described in the article by Nozik and Beard, could lead to remarkable improvement in photovoltaic efficiency by using quantization effects in semiconductor nanostructures (quantum dots, wires or wells). These challenges will not be met without simultaneous improvement in nanoscale characterization methods. Terahertz spectroscopy, discussed in the article by Milot et al is one example of a method that is overcoming the difficulties associated with nanoscale materials characterization by avoiding electrical contacts to nanoparticles, allowing characterization during device operation, and enabling characterization of a single nanoparticle. Besides experimental advances, computational science is also meeting the challenges of nanomaterials synthesis. The article by Kohlstedt and Schatz discusses the computational frameworks being used to predict structure-property relationships in materials and devices, including machine learning methods, with an emphasis on organic photovoltaics. The contribution by Megarity and Armstrong presents the 'electrochemical leaf' for improvements in electrochemistry and beyond. In addition, biohybrid approaches can take advantage of efficient and specific enzyme catalysts. These articles present the nanoscience and technology at the forefront of renewable energy development that will have significant benefits to society.
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| 15. |
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| 16. |
- Callaway, EM, et al.
(author)
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A multimodal cell census and atlas of the mammalian primary motor cortex
- 2021
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In: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 598:7879, s. 86-102
-
Journal article (peer-reviewed)abstract
- Here we report the generation of a multimodal cell census and atlas of the mammalian primary motor cortex as the initial product of the BRAIN Initiative Cell Census Network (BICCN). This was achieved by coordinated large-scale analyses of single-cell transcriptomes, chromatin accessibility, DNA methylomes, spatially resolved single-cell transcriptomes, morphological and electrophysiological properties and cellular resolution input–output mapping, integrated through cross-modal computational analysis. Our results advance the collective knowledge and understanding of brain cell-type organization1–5. First, our study reveals a unified molecular genetic landscape of cortical cell types that integrates their transcriptome, open chromatin and DNA methylation maps. Second, cross-species analysis achieves a consensus taxonomy of transcriptomic types and their hierarchical organization that is conserved from mouse to marmoset and human. Third, in situ single-cell transcriptomics provides a spatially resolved cell-type atlas of the motor cortex. Fourth, cross-modal analysis provides compelling evidence for the transcriptomic, epigenomic and gene regulatory basis of neuronal phenotypes such as their physiological and anatomical properties, demonstrating the biological validity and genomic underpinning of neuron types. We further present an extensive genetic toolset for targeting glutamatergic neuron types towards linking their molecular and developmental identity to their circuit function. Together, our results establish a unifying and mechanistic framework of neuronal cell-type organization that integrates multi-layered molecular genetic and spatial information with multi-faceted phenotypic properties.
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| 17. |
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| 18. |
- Deng, Kaiqiang, et al.
(author)
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A dry-wet teleconnection between southwestern and northeastern China in winter and early spring
- 2024
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In: CLIMATE DYNAMICS. - 0930-7575 .- 1432-0894.
-
Journal article (peer-reviewed)abstract
- Global climate change has led to more frequent and intense dry and wet extremes, causing considerable socio-economic losses, but whether these extremes in distant regions are linked and what mechanisms are driving their changes remain unclear. Based on the standardized precipitation-evapotranspiration index and ERA5 reanalysis data, this study reveals a dry-wet teleconnection between southwestern China (SWC) and northeastern China (NEC) from January to April: when SWC was extremely dry, NEC tended to be anomalously wet, and vice versa. Although the seesawing teleconnection is most significant on interannual time scales, it also experienced interdecadal changes, with wet SWC and dry NEC in 1979-1998 and 2019-present and dry SWC and wet NEC in 1999-2018. Further investigations suggest that the pattern of dry SWC and wet NEC is related to anomalous anticyclones (cyclones) over SWC (NEC), which lead to significant changes in surface temperature and total precipitation in the respective regions. The dryness in western (eastern) SWC is mainly influenced by the changes in temperature (precipitation), while the NEC wetness is affected mainly by the changes in temperature. Observational and modeling studies further suggest that the pressure anomalies over SWC and NEC are caused by zonally and meridionally propagating Rossby wave trains, triggered by the North Atlantic Oscillation and the enhanced Indo-Pacific convection, respectively. These wave trains further lead to hydroclimatic extremes in North America, southern Europe, and the Middle East by regulating the atmospheric circulation anomalies over these regions.
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| 19. |
- Dong, Yi-Min, et al.
(author)
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Development and Validation of a Nomogram for Assessing Survival in Patients With COVID-19 Pneumonia
- 2021
-
In: Clinical Infectious Diseases. - : Oxford University Press. - 1058-4838 .- 1537-6591. ; 72:4, s. 652-660
-
Journal article (peer-reviewed)abstract
- Background. The outbreak of coronavirus disease 2019 (COVID-19) has spread worldwide and continues to threaten peoples' health as well as put pressure on the accessibility of medical systems. Early prediction of survival of hospitalized patients will help in the clinical management of COVID-19, but a prediction model that is reliable and valid is still lacking. Methods. We retrospectively enrolled 628 confirmed cases of COVID-19 using positive RT-PCR tests for SARS-CoV-2 in Tongji Hospital, Wuhan, China. These patients were randomly grouped into a training (60%) and a validation (40%) cohort. In the training cohort, LASSO regression analysis and multivariate Cox regression analysis were utilized to identify prognostic factors for in-hospital survival of patients with COVID-19. A nomogram based on the 3 variables was built for clinical use. AUCs, concordance indexes (C-index), and calibration curves were used to evaluate the efficiency of the nomogram in both training and validation cohorts. Results. Hypertension, higher neutrophil-to-lymphocyte ratio, and increased NT-proBNP values were found to be significantly associated with poorer prognosis in hospitalized patients with COVID-19. The 3 predictors were further used to build a prediction nomogram. The C-indexes of the nomogram in the training and validation cohorts were 0.901 and 0.892, respectively. The AUC in the training cohort was 0.922 for 14-day and 0.919 for 21-day probability of in-hospital survival, while in the validation cohort this was 0.922 and 0.881, respectively. Moreover, the calibration curve for 14- and 21-day survival also showed high coherence between the predicted and actual probability of survival. Conclusions. We built a predictive model and constructed a nomogram for predicting in-hospital survival of patients with COVID-19. This model has good performance and might be utilized clinically in management of COVID-19.
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| 20. |
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| 21. |
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| 22. |
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| 23. |
- Lauerwald, Ronny, et al.
(author)
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Carbon and Greenhouse Gas Budgets of Europe : Trends, Interannual and Spatial Variability, and Their Drivers
- 2024
-
In: Global Biogeochemical Cycles. - 0886-6236. ; 38:8
-
Journal article (peer-reviewed)abstract
- In the framework of the RECCAP2 initiative, we present the greenhouse gas (GHG) and carbon (C) budget of Europe. For the decade of the 2010s, we present a bottom-up (BU) estimate of GHG net-emissions of 3.9 Pg CO2-eq. yr−1 (using a global warming potential on a 100 years horizon), which are largely dominated by fossil fuel emissions. In this decade, terrestrial ecosystems acted as a net GHG sink of 0.9 Pg CO2-eq. yr−1, dominated by a CO2 sink that was partially counterbalanced by net emissions of CH4 and N2O. For CH4 and N2O, we find good agreement between BU and top-down (TD) estimates from atmospheric inversions. However, our BU land CO2 sink is significantly higher than the TD estimates. We further show that decadal averages of GHG net-emissions have declined by 1.2 Pg CO2-eq. yr−1 since the 1990s, mainly due to a reduction in fossil fuel emissions. In addition, based on both data driven BU and TD estimates, we also find that the land CO2 sink has weakened over the past two decades. A large part of the European CO2 and C sinks is located in Northern Europe. At the same time, we find a decreasing trend in sink strength in Scandinavia, which can be attributed to an increase in forest management intensity. These are partly offset by increasing CO2 sinks in parts of Eastern Europe and Northern Spain, attributed in part to land use change. Extensive regions of high CH4 and N2O emissions are mainly attributed to agricultural activities and are found in Belgium, the Netherlands and the southern UK. We further analyzed interannual variability in the GHG budgets. The drought year of 2003 shows the highest net-emissions of CO2 and of all GHGs combined.
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| 24. |
- Li, F., et al.
(author)
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Hydrogen storage behavior in C15 Laves phase compound TiCr2 by first principles
- 2009
-
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 105:4
-
Journal article (peer-reviewed)abstract
- Hydrogen storage in TiCr2 alloy of AB(2) type with C15 Laves phase structure has been studied using density functional theory and plane-wave pseudopotential technique. The H atom interacts stronger with Cr atoms than with Ti and tends to occupy the g (2A2B) site due to the largest interstitial space. The g sites together with e (1A3B) sites form a three-dimensional clathratelike network, providing a diffusion pathway for H atoms, and the energy barriers for the H diffusion along these paths were computed. Interaction between two interstitial H atoms inside the TiCr2 lattice can be considered as a screened Coulomb repulsion, which seems to control the maximum hydrogen content in the metal hydrides. The absorption energies and electronic structures of metal hydrides TiCr2Hx with x=0.5-12 have been computed, and the theoretical maximum hydrogen storage capacity (between 2.6 and 3.8 wt %) agrees with experiments. The effects of the lattice expansion due to hydrogen absorption of different amounts have also been investigated.
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| 25. |
- Liu, Yanrong, et al.
(author)
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Ionic liquids as a new cornerstone to support hydrogen energy
- 2023
-
In: Green Chemistry. - : Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 25:13, s. 4981-4994
-
Research review (peer-reviewed)abstract
- As a fuel or energy carrier, hydrogen has been identified as a key way to decarbonize electricity, industry, transportation, and heating sectors. Hydrogen can be produced by a variety of methods, among which water electrolysis driven by renewable energy is sustainable and nearly carbon-free. To use hydrogen widely, storage and transportation over long distances are another key issue. Apart from storage at high pressure and low temperature, hydrogen can be stored in organic compounds via chemical bonding under relatively mild conditions. Efficient utilization of hydrogen includes hydrogen fuel cells as an alternative to internal combustion engines. From the above scenarios, catalysis and reaction media are the key factors for realizing hydrogen energy implementation. Ionic liquids (ILs) offer new opportunities due to their tunable functional groups, low vapor pressure, and stable structures as additives, solvents, and charge transfer materials. ILs are known to produce solid catalysts with controllable properties, decorate solid catalysts with modified electrons and geometric structures, and serve as electrolytes and hydrogen storage media. This review summarizes and recaps the recent progress in how ILs act as a cornerstone to support the production, storage, and utilization of hydrogen. Furthermore, critical challenges and future research directions of ILs in hydrogen energy applications are also outlined.
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| 26. |
- Tian, Ke, et al.
(author)
-
Blue band nonlinear optics and photodarkening in silica microdevices
- 2022
-
In: Photonics Research. - 2327-9125. ; 10:9, s. 2073-2080
-
Journal article (peer-reviewed)abstract
- There are extensive studies to date on optical nonlinearities in microcavities at the near and mid-IR wavelengths. Pushing this research into the visible region is equally valuable. Here, we demonstrate a directly pumped, blue band Kerr frequency comb and stimulated Raman scattering (SRS) at 462 nm in a silica nanofiber-coupled whispering gallery microcavity system. Notably, due to the high optical intensities achieved, photodarkening is unavoidable and can quickly degrade the optical quality of both the coupling optical nanofiber and the microcavity, even at very low pump powers. Nonetheless, stable hyperparametric oscillation and SRS are demonstrated in the presence of photodarkening by taking advantage of in-situ thermal bleaching. This work highlights the challenges of silica-based, short wavelength nonlinear optics in high-quality, small mode volume devices and gives an effective method to overcome this apparent limitation, thus providing a baseline for optics research in the blue region for any optical devices fabricated from silica.
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| 27. |
- Tian, Ke, et al.
(author)
-
Effect of blockage configuration on film cooling with and without mist injection
- 2018
-
In: Energy. - : Elsevier BV. - 0360-5442. ; 153, s. 661-670
-
Journal article (peer-reviewed)abstract
- Film cooling, as an effective protection technology, is widely applied in gas turbines to prevent components like vane blades from the hot mainstream. However, ash and other contaminants contained in the gas easily deposit on blade surfaces, which results in blockages inside the film holes and a reduction of the coverage area of the coolant air. Two blockage configurations (hemispherical and tetrahedral blockages) with a similar blockage ratio are analyzed in this study. In addition, mist injection with three droplet sizes (1 μm, 5 μm and 10 μm) is also considered. It is found that the position of the blockage configuration shows almost no influence on the cooling performance. In addition, the hemispherical blockage configuration results in a lower lateral film cooling effectiveness than the tetrahedral one. Finally, it is also concluded that the 5 μm droplet case shows more uniform distribution than other cases.
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| 28. |
- Tian, Ke, et al.
(author)
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Effect of combined hole configuration on film cooling with and without mist injection
- 2018
-
In: Thermal Science. - 0354-9836. ; 22:5, s. 1923-1931
-
Journal article (peer-reviewed)abstract
- Turbine blades operate under a harsh environmental condition, and the inlet temperature of gas turbines is increasing with requirement of high engine effi-ciency. Some cooling schemes are adopted to prevent these blades from the ther-mal erosion of the hot mainstream. Film cooling technology is used widely and effectively in gas turbines. The coolant air is suppressed to the wall by the main-stream after jetting out of the film hole. A new hole configuration is first pro-posed to improve the film cooling characteristics in this paper. Comparison be-tween a conventional cylindrical hole and a new combined hole is conducted by CFD, and effects of various blowing ratios and droplet sizes are also investigat-ed. Results show that the combined hole configuration provides a wider coverage than that in the cylindrical hole configuration case at high blowing ratios (M = 1.0 and M = 1.5). In addition, the film cooling with mist injection also provides a significant enhancement on cooling performance especially for the combined hole case with a small droplet size (10-5 m).
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| 29. |
- Wan, Sushu, et al.
(author)
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All-Optical Switching Based on Sub-Bandgap Photoactivation of Charge Trapping in Metal Halide Perovskites
- 2023
-
In: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 35:13
-
Journal article (peer-reviewed)abstract
- Controllable optical properties are crucial for the application of light-emitting materials in optical devices. In this work, controllable photoluminescence in metal halide perovskite crystals is realized via photoactivation of their defects. It is found that under continuous excitation, the photoluminescence intensity of a CH3NH3PbBr3 crystal can be fully controlled by sub-bandgap energy photon illumination. Such optically controllable emission behavior is rather general as it is observed also in CsPbBr3 and other perovskite materials. The switching mechanism is assigned to reversible light-induced activation/deactivation of nonradiative recombination centers, the presence of which relates to an excess of Pb during perovskite synthesis. Given the success of perovskites in photovoltaics and optoelectronics, it is believed that the discovery of green luminescence controlled by red illumination will extend the application scope of perovskites toward optical devices and intelligent control.
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| 30. |
- Wang, Jin, et al.
(author)
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A review on nanofluid stability : preparation and application
- 2023
-
In: Renewable and Sustainable Energy Reviews. - 1364-0321. ; 188
-
Journal article (peer-reviewed)abstract
- Due to excellent thermal performance and application prospects, nanofluids are attracting many researchers to pay more attention to new types of heat transfer fluids. However, previous studies have focused on the effects of nanofluids on thermophysical properties without considering the limitation of dispersion stability in practical applications. Excellent nanofluid stability is judged with the zeta potential value above 30 mV. Unstable nanofluids block the fluid flow in heat exchanger channels, which reduces the system performance by over 23 %. Based on a systematic review of improving nanofluid stability, this research discusses the preparation, characterisation, influencing factor, dispersion mechanism, and dispersion method on nanofluid stability. Four methods for improving nanofluid stability are summarised. The nanofluid is stable at pH values between 4 and 9 b y controlling its ionic concentration. The nanofluid concentration is required below 2 % to improve the repulsion between nanoparticles. The stability of the nanofluid is affected by the type and amount of the surfactant, which fails to improve the nanofluid stability at temperature above 60 °C. In addition, the molecular forces between the mixed nanofluids enhance the stability of the nanofluid. This review examines the variation patterns of nanofluid stability and the effect of stability on heat transfer. It is expected to identify some opportunities and demonstrate future challenges in both the in-lab research and the commercialisation of nanofluids.
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| 31. |
- Wang, Jin, et al.
(author)
-
Effect of hole configurations on film cooling performance
- 2019
-
In: Numerical Heat Transfer; Part A: Applications. - : Informa UK Limited. - 1040-7782 .- 1521-0634. ; 75:11, s. 725-738
-
Journal article (peer-reviewed)abstract
- This study aims to investigate the cooling performance of various film cooling holes, including combined hole, cylinder hole, conical hole, and fan-shaped hole. For film cooling technology, a novel combined hole configuration is first proposed to improve the cooling protection for gas turbine engines. This combined hole consists of a central cylinder hole (an inclination angle of 35°) and two additional side holes (a lateral diffusion angle of 30°). Film holes for four-hole configurations have the same inlet diameter of 8 mm. The adiabatic film cooling effectiveness for each hole configuration is analyzed for varying blowing ratios (M = 0.25, 0.5, 0.75, and 1.0). Results show that the best cooling performance for the conical and fan-shaped holes is obtained at the blowing ratio of 0.75. In addition, the combined hole configuration provides a more uniform cooling protection and a better cooling performance than the other hole configurations.
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| 32. |
- Wang, Jin, et al.
(author)
-
Effect of spherical blockage configurations on film cooling
- 2018
-
In: Thermal Science. - 0354-9836. ; 22:5, s. 1933-1942
-
Journal article (peer-reviewed)abstract
- With increasing inlet temperature of gas turbines, turbine blades need to be effec-tively protected by using cooling technologies. However, the deposition from the fuel impurities and dust particles in the air is often found inside film holes, which results in partial hole blockage. In this paper, the deposition geometry is simpli-fied as a rectangular channel, and the effect of three blockage ratios is investi-gated by using the computational fluid dynamics. In addition, water droplets are also released from the coolant inlet to provide a comparison of the results with and without mist injection. It is found that the lateral film cooling effectiveness is reduced with increasing blockage ratio. For all the cases with the blowing ratio 0.6, 1% mist injection provides an improvement of the cooling performance by approximately 10%.
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| 33. |
- Wang, Jin, et al.
(author)
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Numerical investigation of particle deposition in film-cooled blade leading edge
- 2020
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In: Numerical Heat Transfer; Part A: Applications. - : Informa UK Limited. - 1040-7782 .- 1521-0634. ; 77:6, s. 579-598
-
Journal article (peer-reviewed)abstract
- This study numerically investigates film-cooling performance and particle trajectories in AGTB (two rows of cylindrical holes equipped on suction side (SS) and pressure side (PS) of the leading edge, respectively) turbine cascade. Particle deposition on a turbine blade is analyzed by calculations of capture efficiency and impact efficiency. The turbulent flow is modeled by the Realizable k-ε turbulence model, and the discrete phase model (DPM) with user-defined functions (UDFs) is used to simulate the particle motions. An invasion efficiency is proposed to analyze the possibility of particle invasion into the film hole. Comparisons of various particles with diameters of 1 µm, 5 µm, 10 µm, 20 µm, and 50 µm, respectively, are conducted for four blowing ratios (0.53, 0.93, 1.31, 1.63) and three inlet flow angles (123°, 133°, and 143°). It is observed that with a small inlet flow angle and a large blowing ratio, the capture efficiency on the PS decreases. It is found that smaller particle size results in lower invasion efficiency, and larger particles are more likely to invade into the film-cooling hole especially at a low blowing ratio.
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| 34. |
- Wang, Lanhui, et al.
(author)
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Asymmetric patterns and temporal changes in phenology-based seasonal gross carbon uptake of global terrestrial ecosystems
- 2020
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In: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 29:6, s. 1020-1033
-
Journal article (peer-reviewed)abstract
- Aim: To study global patterns and temporal changes in the seasonal dynamics (quantity and seasonal distribution) of terrestrial gross carbon uptake in response to global environmental change. Location: Global. Time period: 2000–2016. Major taxa studied: Terrestrial ecosystems. Methods: Following a phenology-based definition of photosynthetic seasonality, we decompose gross primary production (GPP) into three periods, green-up, maturity and senescence, and derive their corresponding GPP (GPPgp, GPPmp and GPPsp, respectively) from a newly developed time series of satellite-based global GPP to study spatio-temporal dynamics of seasonal GPP. Results: We find that the global fraction of GPPsp (19.8%) is larger than GPPgp (14.3%), indicating a globally asymmetric seasonal distribution of gross carbon uptake by terrestrial ecosystems. Globally, GPPmp plays a dominant role in shaping spatial patterns and increasing/decreasing trends in GPP, while GPPgp/GPPsp contributes to increasing GPP at the regional scale. Higher fractions of GPPgp/GPPmp (lower of GPPsp), as well as the co-occurrence of increasing GPP and non-tree vegetation cover in major croplands, are likely to be caused by agricultural intensification. Global changes in GPPgp and GPPsp are closely related to changes in their seasonal distributions (R =.86/.8, respectively), whereas this relationship is weaker for GPPmp (R =.53). Finally, high correlations are observed between changes in GPPgp and GPPsp and changes in their durations (R =.78/.78, respectively), while GPPmp shows a relatively lower correlation with its duration (R =.67). Main conclusions: The asymmetric spatio-temporal patterns in the seasonal dynamics of global terrestrial gross carbon uptake found here have been substantially reshaped by anthropogenic land-use/cover changes and changes in photosynthetic phenology. Compared to calendar-based meteorological seasons more suitable for temperate/subpolar ecosystems, our phenology-based approach is expected to provide an alternative starting point for a better understanding of global spatio-temporal changes in the seasonal dynamics of terrestrial ecosystem processes and functioning under accelerating global change.
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| 35. |
- Wang, Nana, et al.
(author)
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Perovskite light-emitting diodes based on solution-processed self-organized multiple quantum wells
- 2016
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In: Nature Photonics. - : NATURE PUBLISHING GROUP. - 1749-4885 .- 1749-4893. ; 10:11, s. 699-
-
Journal article (peer-reviewed)abstract
- Organometal halide perovskites can be processed from solutions at low temperatures to form crystalline direct-bandgap semiconductors with promising optoelectronic properties(1-5). However, the efficiency of their electroluminescence is limited by non-radiative recombination, which is associated with defects and leakage current due to incomplete surface coverage(6-9). Here we demonstrate a solution-processed perovskite light-emitting diode (LED) based on self-organized multiple quantum wells (MQWs) with excellent film morphologies. The MQW-based LED exhibits a very high external quantum efficiency of up to 11.7%, good stability and exceptional highpower performance with an energy conversion efficiency of 5.5% at a current density of 100 mA cm(-2). This outstanding performance arises because the lower bandgap regions that generate electroluminescence are effectively confined by perovskite MQWs with higher energy gaps, resulting in very efficient radiative decay. Surprisingly, there is no evidence that the large interfacial areas between different bandgap regions cause luminescence quenching.
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| 36. |
- Wang, Yu-Cheng, et al.
(author)
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Porous Carbon Membrane-Supported Atomically Dispersed Pyrrole-Type Fe-N-4 as Active Sites for Electrochemical Hydrazine Oxidation Reaction
- 2020
-
In: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 16:31
-
Journal article (peer-reviewed)abstract
- The rational design of catalytically active sites in porous materials is essential in electrocatalysis. Herein, atomically dispersed Fe-N-x sites supported by hierarchically porous carbon membranes are designed to electrocatalyze the hydrazine oxidation reaction (HzOR), one of the key techniques in electrochemical nitrogen transformation. The high intrinsic catalytic activity of the Fe-N-x single-atom catalyst together with the uniquely mixed micro-/macroporous membrane support positions such an electrode among the best-known heteroatom-based carbon anodes for hydrazine fuel cells. Combined with advanced characterization techniques, electrochemical probe experiments, and density functional theory calculation, the pyrrole-type Fe-N-4 structure is identified as the real catalytic site in HzOR.
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| 37. |
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| 38. |
- Yang, Xigui, et al.
(author)
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Novel Superhard sp3 Carbon Allotrope from Cold-Compressed C70 Peapods
- 2017
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In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 118:24
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Journal article (peer-reviewed)abstract
- Design and synthesis of new carbon allotropes have always been important topics in condensed matter physics and materials science. Here we report a new carbon allotrope, formed from cold-compressed C70 peapods, which most likely can be identified with a fully sp3-bonded monoclinic structure, here named V carbon, predicted from our simulation. The simulated x-ray diffraction pattern, near K-edge spectroscopy, and phonon spectrum agree well with our experimental data. Theoretical calculations reveal that V carbon has a Vickers hardness of 90 GPa and a bulk modulus ∼400 GPa, which well explains the "ring crack" left on the diamond anvils by the transformed phase in our experiments. The V carbon is thermodynamically stable over a wide pressure range up to 100 GPa, suggesting that once V carbon forms, it is stable and can be recovered to ambient conditions. A transition pathway from peapod to V carbon has also been suggested. These findings suggest a new strategy for creating new sp3-hybridized carbon structures by using fullerene@nanotubes carbon precursor containing odd-numbered rings in the structures.
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| 39. |
- Yang, Xian, et al.
(author)
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Thermal-hydraulic performance of printed circuit heat exchangers with various channel shapes under rolling conditions
- 2024
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In: Applied Thermal Engineering. - 1359-4311. ; 244
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Journal article (peer-reviewed)abstract
- The floating liquefied natural gas (LNG) facilities are located in deep oceans, where the harsh ocean conditions cause the facilities to sway and tilt. The rolling conditions in floating LNG systems affect the uniformity of gas–liquid distribution in heat exchangers. Thermal and hydraulic performances of printed circuit heat exchangers (PCHEs) with straight, zigzag, and trapezoidal channels are investigated under static and rolling conditions. The results reveal that all channels enhance heat transfer near the pseudo-critical point of LNG at a rolling period of 2 s and a rolling amplitude of 15°. The Nusselt number for the PCHE with a zigzag channel increases by 32.2% and 72.5% compared to those with straight and trapezoidal channels. The highest increase in comprehensive performance is obtained for the zigzag channel with an evaluation index of 1.23 under the rolling condition. Compared with under the static condition, the Nusselt number and Fanning friction factor for the zigzag channel increase by 12% and 28% under the rolling condition. The thermal performance is weakened by the nonuniform flow velocity and improved by the enhancement of flow turbulence. The thermal–hydraulic performance increases with the rolling period from 1 s to 3 s and the rolling amplitude from 15° to 45°. The maximum improvement of 65.3% and 97.2% in Nusselt number and Fanning friction factors is observed at a rolling period of 1 s and a rolling amplitude of 45°. The methods to suppress the deterioration of heat transfer in microfluidic channels under rolling conditions are proposed to satisfy the requirement of LNG with low-resistance and high-efficiency microfluidic structure.
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