| 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. |
- Hu, Rukun, et al.
(författare)
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Design and assessment on a bottom-cut shape for latent heat storage tank filled with metal foam
- 2024
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Ingår i: International Journal of Thermal Sciences. - 1290-0729. ; 197
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Tidskriftsartikel (refereegranskat)abstract
- The utilization of phase change materials (PCMs) holds tremendous potential of heat storage domain. The PCM's refractory at the latent heat thermal energy storage (LHTES) unit bottom hinders the heat storage efficiency, despite the significant improvement in thermal conductivity achieved through the addition of metal foam. This study employs numerical simulation to examine the impact of applying bottom cross-cut on PCM's spatial distribution in a horizontal LHTES unit. The manuscript analyzes parameters including melting fraction, complete melting time, Rayleigh number, natural convection heat transfer gain, melting phase interface, velocity and temperature distributions, and heat storage. The findings indicate that the proximity to the heating tube results in a reduction of solid volume at the LHTES unit bottom. A 0.6 bottom cross-cut ratio leads to an 18.84 % faster heat storage rate compared to a concentric-circle unit. Furthermore, a bottom cross-cut ratio of 0.5 enhances natural convection heat transfer gain by 3.28 times.
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| 3. |
- Chen, Xinyu, et al.
(författare)
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Variations in electrical impedance and phase angle among seedlings of Pinus densata and parental species in Pinus tabuliformis habitat environment
- 2015
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Ingår i: Journal of Forestry Research. - : Northeast Forestry University. - 1007-662X .- 1993-0607. ; 26:3, s. 777-783
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Tidskriftsartikel (refereegranskat)abstract
- Electrical impedance (EI) and phase angle (PHI) parameters in AC impedance spectroscopy are important electrical parameters in the study of medical pathology. However, little is known about their application in variation and genetic relationship studies of forest trees. In order to test whether impedance parameters could be used in genetic relationship analysis among conifer species, EI and PHI were measured in a seedling experiment test composed of Pinus tabuliformis, Pinus yunnanensis, and Pinus densata in a habitat of Pinus tabuliformis. The results showed that variations in both EI and PHI among species were significant in different electric frequencies, and the EI and PHI values measured in the two populations of P. densata were between the two parental species, P. yunnanensis and P. tabuliformis. These results show that these two impedance parameters could reflect the genetic relationship among pine species. This was the first time using the two AC impedance spectroscopy parameters to test the genetic relationship analysis between tree species, and would be a hopeful novel reference methodology for future studies in evolution and genetic variation of tree species.
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| 4. |
- Chen, Yinglu, et al.
(författare)
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Heavy sulfur isotopes recorded in contrasted redox conditions in Holocene sediments from the Yangtze River Delta
- 2024
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Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 663
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur isotopic signatures of pyrite (δ34Spy) sensitively react to local environmental change. Here we elucidate mechanism of δ34Spy variation in the Holocene sedimentary strata of the Yangtze River Delta, through the analyses of multiple geochemical and physical indicators including total organic carbon, total nitrogen, stable isotopes of organic carbon, different iron solid phases, Sr/Ba ratios, and changes in sedimentation rates. Two heavy δ34Spy (∼30‰) layers that formed under contrasting redox conditions are preserved in the early Holocene transgressive tidal flat and late Holocene regressive mouth bar facies, respectively. Two hypotheses are proposed to explain these heavy δ34Spy layers: 1) in the transgression process, the heavy δ34Spy layers formed under stronger reducing conditions due to methane leakage; 2) in the regression process, the heavy δ34Spy layers formed under relatively weaker reducing conditions due to rapid deposition and low salinity. This study emphasizes the importance of physicochemical condition characterization in sediments, including redox conditions, in distinguishing the mechanisms that act to produce heavy δ34Spy signals.
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| 5. |
- Cheng, Zhaowei, et al.
(författare)
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Using deep learning to accelerate magnetic resonance measurements of molecular exchange
- 2023
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 159:5
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Tidskriftsartikel (refereegranskat)abstract
- Real-time monitoring and quantitative measurement of molecular exchange between different microdomains are useful to characterize the local dynamics in porous media and biomedical applications of magnetic resonance. Diffusion exchange spectroscopy (DEXSY) is a noninvasive technique for such measurements. However, its application is largely limited by the involved long acquisition time and complex parameter estimation. In this study, we introduce a physics-guided deep neural network that accelerates DEXSY acquisition in a data-driven manner. The proposed method combines sampling pattern optimization and physical parameter estimation into a unified framework. Comprehensive simulations and experiments based on a two-site exchange system are conducted to demonstrate this new sampling optimization method in terms of accuracy, repeatability, and efficiency. This general framework can be adapted for other molecular exchange magnetic resonance measurements.
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| 6. |
- Huang, Kun, et al.
(författare)
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Effect of acidosis on adipose-derived stem cell impairment and gene expression
- 2024
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Ingår i: Regenerative Therapy. - 2352-3204. ; 25, s. 331-343
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Tidskriftsartikel (refereegranskat)abstract
- Based on disappointing results of stem cell-based application in clinical trials for patients with critical limb ischemia, we hypothesized that the acidic environment might be the key factor limiting cell survival and function. In the present study, we used microdialysis to determine presence of acidosis and metabolic imbalance in critical ischemia. Moreover, we explored the effect of extracellular acidosis on adipose-derived stem cells (ADSCs) at molecular and transcriptional level. Our data demonstrate that low pH negatively regulates cell proliferation and survival, also, it results in cell cycle arrest, mitochondrial dynamics disorder, DNA damage as well as the impairment of proangiogenic function in a pH-dependent manner. Further transcriptome profiling identified the pivotal signaling pathways and hub genes in response to acidosis. Collectively, these findings provide strong evidences for a critical role of acidosis in ADSCs impairment with ischemic condition and suggest treatments focus on tissue pH balance and acidosis-mediated hub genes may have therapeutic potential in stem cell-based application.
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| 7. |
- Ma, Xiang, et al.
(författare)
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Flow boiling frictional pressure drop inside micro/mini-channels : A new general model and experimental investigation
- 2024
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Ingår i: Applied Thermal Engineering. - 1359-4311. ; 247
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a novel general model for flow boiling frictional pressure drop inside micro/mini-channels was proposed based on theoretical analysis and experimental evaluation. Experiments were conducted to obtained flow boiling pressure drop of deionized water, HFE7100 and R134a in micro-channels under various experimental conditions. Then, a wide database from 33 previous literatures consists 3854 experimental data points covering 11 different working fluids, e.g., carbon dioxide, new electronic fluorinated solutions, refrigerants and deionized water, among others, and the operation conditions were as following: system temperature of −40–90 ℃, saturated pressure of 101–3970 kPa, hydraulic diameter of 0.1–2.6 mm, liquid subcooling of 5–75 K, mass flux of 50–3000 kg/(m2·s), heat flux of 0–4000 kW/m2, liquid-only Reynolds number of 40–12,000, vapor quality of 0–1, and reduced pressure of 0.0045–0.5380 in the database. Both the Reynolds numbers of vapor and liquid were calculated using the hydraulic diameter and vapor quality. The present data points were evaluated by 20 existing classical models (including the homogeneous and separated flow ones) for the flow boiling frictional pressure drop. However, the predictions of these models for the present data points had low accuracy, especially for the subcooled points at low vapor quality. Therefore, a more accurate prediction model was developed based on the present database by distinguishing the subcooled and saturated boiling. This novel prediction model can predict 75.4 % and 89.7 % of data points within ±30 % and ±50 % error bands, its mean absolute percent error (MAPE) is 19.23 %, which shows good predictive ability. Besides, the reliability of the new model was also further verified with our experimental results.
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| 8. |
- Zhu, Shihao, et al.
(författare)
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A novel fuel cell cathode hybrid intake structure design and control for integrated hydrogen energy utilization system
- 2024
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Ingår i: Energy. - 1873-6785 .- 0360-5442. ; 308
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Tidskriftsartikel (refereegranskat)abstract
- The typical Integrated Hydrogen Energy Utilization System (IHEUS) does not recycle oxygen. For maximizing the system's efficiency, this study proposes a method for recycling byproduct oxygen in a Fuel Cell (FC) hybrid cathode intake structure and its control. By introducing the pure oxygen produced as a byproduct of hydrogen production into the FC, a hybrid cathode intake structure is formed with the air branch. To control this structure, models of the oxygen and air branch, and the FC stack are established. Subsequently, using BiLSTM network to learn historical data and extract relevant features, the output power demand of the FC system is predicted. Based on the prediction results, the required gas flow is calculated, and a fuzzy PID control strategy is employed to adjust the opening of the solenoid valve to change the gas flow to meet the demand. Finally, comparative studies show that our FC system, operating in a pure oxygen state, outperforms conventional air intake design: heat production increases by 13 %, electric efficiency improves by 20 %, and pure water savings reach 65.57 %. The air compressor witnesses a substantial 37.63 % reduction in power consumption, contributing to an overall energy efficiency increase of 8.92 % for the IHEUS.
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