| 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. |
- Fu, Yifeng, 1984, et al.
(författare)
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Ultrafast Transfer of Metal Enhanced Carbon Nanotubes at Low Temperature for Large Scale Electronics Assembly
- 2010
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 22:44, s. 5039-5042
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Tidskriftsartikel (refereegranskat)abstract
- An indium-assisted ultrafast carbon nanotube (CNT) transfer method with a yield rate over 90% is described. Metal-coated as-transferred CNT structures exhibit excellent electrical performance that is at least one order of magnitude better than the previously published results. Shear test results show that the adhesion between CNTs and the substrate is greatly improved and excellent flexibility is obtained after the transfer process.
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| 3. |
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| 4. |
- Liu, Xiao, et al.
(författare)
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Investigation of transient ignition process in a cavity based scramjet combustor using combined ethylene injectors
- 2017
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Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 137, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Large Eddy Simulation (LES) and experiment were employed to investigate the transient ignition and flame propagation process in a rearwall-expansion cavity scramjet combustor using combined fuel injection schemes. The compressible supersonic solver and three ethylene combustion mechanisms were first validated against experimental data and results show in reasonably good agreement. Fuel injection scheme combining transverse and direct injectors in the cavity provides a benefit mixture distribution and could achieve a successful ignition. Four stages are illustrated in detail from both experiment and LES. After forced ignition in the cavity, initial flame kernel propagates upstream towards the cavity front edge and ignites the mixture, which acts as a continuous pilot flame, and then propagates downstream along the cavity shear layer rapidly to the combustor exit. Cavity shear layer flame stabilization mode can be concluded from the heat release rate and local high temperature distribution during the combustion process.
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| 5. |
- Qin, Yiheng, 1987, et al.
(författare)
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Organic Thin-Film Transistors with Anodized Gate Dielectric Patterned by Self-Aligned Embossing on Flexible Substrates
- 2012
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 22:6, s. 1209-1214
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Tidskriftsartikel (refereegranskat)abstract
- An upscalable, self-aligned patterning technique for manufacturing high- performance, flexible organic thin-film transistors is presented. The structures are self-aligned using a single-step, multi-level hot embossing process. In combination with defect-free anodized aluminum oxide as a gate dielectric, transistors on foil with channel lengths down to 5 mu m are realized with high reproducibility. Resulting on-off ratios of 4 x 106 and mobilities as high as 0.5 cm2 V-1 s-1 are achieved, indicating a stable process with potential to large-area production with even much smaller structures.
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| 6. |
- Tong, Yiheng, et al.
(författare)
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Effects of the position of a bluff-body on the diffusion flames : A combined experimental and numerical study
- 2018
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 131, s. 507-521
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Tidskriftsartikel (refereegranskat)abstract
- The effects of the position of a bluff-body on diffusion flame structures and flame instability characteristics were investigated both experimentally and numerically. The flame pattern diagram and the stability limits of the methane-air diffusion flame were investigated to evaluate the effects caused by the alternation of the position of a bluff-body. A disk-shape bluff-body was mounted 10 mm above or at the same height with the annular channel exit. The bulk velocity of the annular air flow varied between Ua = 0 to 8 m/s; while the fuel jet velocity being ranged from Uj = 0 to 30 m/s. Various flame patterns, including the recirculation zone flame, the stable diffusion flame, the split flame and the lifted flame till flame blowoff, were observed and recorded by the high-speed camera. High-speed Particle Image Velocimetry (PIV) was also adopted to give deeper insight into the characteristics of the flow fields and the flame patterns. The hybrid RANS/LES model was utilized to simulate the mixing characters of the reactants, the scalar dissipation rates, the flow fields and their interactions with the flame structures. The size and strength of the recirculation zones downstream of the bluff-body altered with the change in the position of the bluff-body. It is found that flames in burners with two different bluff-body positions behave similarly with each other, except those under conditions with high annular air velocities (Ua > 6.8 m/s). Mounting the bluff-body 10 mm above the annular channel exit could better stabilize the flame. A recirculation vortex was found adjacent to the outer wall of the bluff-body. It played an important role in the flame stabilization. Combustion affected the flow fields significantly by accelerating the central jet and enlarging the outer recirculation zone.
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| 7. |
- Tong, Yiheng, et al.
(författare)
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Experimental and numerical study on bluff-body and swirl stabilized diffusion flames
- 2018
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 217, s. 352-364
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Tidskriftsartikel (refereegranskat)abstract
- Bluff-body and swirl flow are commonly utilized to stabilize diffusion flames in industrial applications, such as gas turbines, ramjets and furnaces. Flame stabilization mechanisms of these two kinds of burners are similar with each other: the interaction between the recirculation zone and the fuel jet. In the present paper, flow fields within flames stabilized by combinations of swirl flow and bluff-body were captured using high-speed PIV; while the flame structures were visualized by high-speed CH2O PLIF, CH∗ chemiluminescence and broadband chemiluminescence. The global CO emissions from the flames were captured as well. In addition, based on the CFD software OpenFOAM, simulations were adopted to better understand the interactions between flames and flow structures. Flames stabilized by bluff-bodies with different diameters (db = 14 mm and 20 mm), or only by swirl flow without a bluff-body, were studied. All reacting experiments were carried out with a constant mass flow rate of the central fuel jet (with thermal power 2.01 kW) and a constant mass flow rate of the total air flow (m = mt + ma = 200 ln/min). The swirl strength was controlled by the mass flow rate ratio of the tangential to the axial air flow. The geometrical swirl number was altered between Sg = 0 and Sg = 4.08. Simulation results matched well with experimental data, especially in predicting the spatial distribution of CH2O. The position of the outer recirculation zone would be affected by the size of the bluff-body and the swirl strength. In addition, the recirculation zone determined the flame structures and the global CO emission levels. With a larger bluff-body, the air driven recirculation zone located more upstream near the burner exit. Flame prone to be more stable with a larger bluff-body and/or a stronger swirl flow. Flame was observed propagating into the upstream region in cases without a bluff-body or in cases with the small bluff-body (db = 14 mm), when the swirl strength was sufficiently strong. The mechanism for the diffusion flame ‘flashback’ was proposed. Flames in cases with a larger swirl number were shorter while its CO emission levels were higher.
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| 8. |
- Tong, Yiheng, et al.
(författare)
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Experimental study on dynamics of a confined low swirl partially premixed methane-hydrogen-air flame
- 2017
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 42:44, s. 27400-27415
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Tidskriftsartikel (refereegranskat)abstract
- The addition of hydrogen to swirl stabilized methane-air flame in gas turbine has gained more and more attentions in recent years. In the current study, flame structures, flame dynamics and lean blowout limits of partially premixed hydrogen-methane-air flames were investigated. The swirling flow, which was generated from the tangential flow injection, was utilized to stabilize the flame. The flow swirl number was kept low varying from S ≈ 0.28 to S ≈ 0.34 while the thermal power of the burner ranged from 10.8 kW to 13.8 kW. Two different fuel injection strategies were investigated and compared with each other. Long exposure CH* chemiluminescence from the flame was captured to visualize the time averaged flame shapes. In addition, an intensified high speed camera was adopted to study the flame dynamics. A high speed PIV system was utilized to investigate the interaction of flame dynamics and flow fields oscillations. Based on the experimental results, it can be concluded that: in the current experimental cases, fuel injection strategy plays an important role in determining the flame macro-structures and thus strongly affects the flame dynamics and lean blowout limits. Flame with fuel injected through the axial flow has lower lean blowout limits. The flashback and vortex breakdown were observed when fuel was injected in the tangential flow near lean blowout. High frequency flame oscillations (f ≈ 170 Hz) were observed when the global equivalence ratio Φ g > 0.72 while lower frequency oscillations (f ≈ 50 Hz and f ≈ 20 Hz) were found near lean blowout limits, Φ g < 0.55. Combustion dynamic and its interaction with the pressure oscillation, flow fields alternation and mass flow rate oscillation are proposed. The differences on fuel concentration at the burner exit are proposed as the main reason for different flame instabilities and flame structures.
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| 9. |
- Yuan, Feifei, et al.
(författare)
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Changes in precipitation extremes over the source region of the Yellow River and its relationship with teleconnection patterns
- 2020
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Ingår i: Water. - 2073-4441. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Precipitation extremes and their underlying causes are important processes to understand to plan appropriate adaptation measures. This paper presents an analysis of the spatiotemporal variability and trend of precipitation extremes in the important source region of the Yellow River and explores the connection to global teleconnection patterns and the 850-mb vector wind. Six indices for precipitation extremes were computed and analyzed for assessment of a changing regional climate. Results showed that these indices have a strong gradient from the northwest to the southeast part for the period 1961-2015, due to the great influence from the south-easterly summer monsoon flow. However, no statistically significant trends were found for the defined indices at the majority of stations, and their spatial distribution are noticed by irregularly mixed positive and negative changes except for the maximum number of consecutive wet days (CWD). Singular value decomposition analysis revealed that the precipitation extreme indices-including annual total precipitation when daily precipitation >95th percentile (R95p), annual count of days with daily precipitation ≥10 mm (R10mm), annual maximum consecutive 5-day precipitation (R5d), total precipitation divided by the number of wet days (SDII), and CWD-are negatively related to the El Nino-Southern Oscillation (NINO 3.4) in the first mode, and the maximum number of consecutive dry days (CDD) is positively related to the Scandinavian pattern in the second mode at 0.05 significance level. The 850-mb vector wind analysis showed that the southwestern monsoon originating from the Indian Ocean brings sufficient moisture to this region. Furthermore, the anti-cyclone in the western part of the North Pacific plays a significant role in the transport of moisture to the source region of the Yellow River. The links between precipitation extremes and teleconnection patterns explored in this study are important for better prediction and preparedness of climatic extremes.
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