| 1. |
- Beal, Jacob, et al.
(författare)
-
Robust estimation of bacterial cell count from optical density
- 2020
-
Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
-
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.
|
|
| 2. |
- Chen, Jinhan, et al.
(författare)
-
The effect of hot isostatic pressing on thermal conductivity of additively manufactured pure tungsten
- 2020
-
Ingår i: International journal of refractory metals & hard materials. - : Elsevier BV. - 0263-4368. ; 87
-
Tidskriftsartikel (refereegranskat)abstract
- The crack-healing behaviors and microstructure evolution of pure tungsten produced by laser powder bed fusion (LPBF) were studied and compared before and after post hot isostatic pressing (post-HIP) treatment. An average thermal conductivity of 133 W.m(-1).K-1 at room temperature (RT) was obtained after HIP, which was 16% higher than that of as-built sample (115 W.m(-1).K-1). Although the HIP process had little effect on density, it resulted in a large grain size of > 300 mu m accompanied by a decrease in dislocation density and crack healing, which led to a substantial improvement of thermal conductivity of pure tungsten. The positive correlation between relative density and thermal conductivity of as-built tungsten was reported.
|
|
| 3. |
- Guo, Yangyi, et al.
(författare)
-
The use of the general thermal sensation discriminant model based on CNN for room temperature regulation by online brain-computer interface
- 2023
-
Ingår i: Building and Environment. - : Elsevier Ltd. - 0360-1323 .- 1873-684X. ; 241
-
Tidskriftsartikel (refereegranskat)abstract
- Brain-computer interface (BCI) technology can realize dynamic room temperature adjustment based on individual real-time thermal sensation, which can provide the basis for future intelligent buildings. However, the generalization ability of previous thermal sensation discrimination model (TSDM) is limited, which is a serious obstacle to the application. In this paper, a general TSDM was developed by using convolutional neural network (CNN), which can be well applied to new subjects. In the study, the CNN-TSDM was established and evaluated based on the offline experimental data, and then the BCI closed-loop online room temperature control experiment was carried out based on this CNN-TSDM to further verify. The offline analysis results show that the recognition performance of CNN-TSDM in new subjects is significantly higher than that of typical shallow learning algorithms, and its area under the ROC curve (AUC) value reaches 0.789. In the online experiments of the two simulated environments, BCI using the CNN-TSDM dynamically controlled the air conditioning to improve the room temperature to the comfortable level according to the subjects' thermal sensation. The subjective score of subjects decreased from 3.1 to 3.0 for the hot uncomfortable to 1.1 and 1.2 for the cool comfortable (p < 0.001, p < 0.001). Moreover, in a hotter simulated experimental environment, BCI automatically controlled the air conditioner for longer cooling to obtain a same degree of thermal comfort. The total cooling time (p < 0.05) and the single cooling time (p < 0.05) of the air conditioner were significantly increased. This further confirmed the effectiveness and robustness of the general CNN-TSDM.
|
|
| 4. |
- He, Xiaohe, et al.
(författare)
-
Real-time regulation of room temperature based on individual thermal sensation using an online brain–computer interface
- 2022
-
Ingår i: Indoor Air. - : NLM (Medline). - 0905-6947 .- 1600-0668. ; 32:e13106
-
Tidskriftsartikel (refereegranskat)abstract
- Regulation of indoor temperature based on neurophysiological and psychological signals is one of the most promising technologies for intelligent buildings. In this study, we developed a system for closed-loop control of indoor temperature based on brain-computer interface (BCI) technology for the first time. Electroencephalogram (EEG) signals were collected from subjects for two room temperature categories (cool comfortable and hot uncomfortable) and used to build a thermal-sensation discrimination model (TSDM) with an ensemble learning method. Then, an online BCI system was developed based on the TSDM. In the online room temperature control experiment, when the TSDM detected that the subjects felt hot and uncomfortable, BCI would automatically turn on the air conditioner, and when the TSDM detected that the subjects felt cool and comfortable, BCI would automatically turn off the air conditioner. The results of online experiments in a hot environment showed that a BCI could significantly improve the thermal comfort of subjects (the subjective thermal comfort score decreased from 2.45 (hot uncomfortable) to 0.55 (cool comfortable), p < 0.001). A parallel experiment further showed that if the subjects wore thicker clothes during the experiment, the BCI would turn on the air conditioner for a longer time to ensure the thermal comfort of the subjects. This has further confirmed the effectiveness of TSDM model in evaluating thermal sensation under the dynamic change of room temperature and showed the model's good robustness. This study proposed a new paradigm of human-building interaction, which is expected to play a promising role in the development of human-centered intelligent buildings.
|
|
| 5. |
- Liu, Kun, et al.
(författare)
-
A study of intrinsic amorphous silicon thin film deposited on flexible polymer substrates by magnetron sputtering
- 2016
-
Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 449, s. 125-132
-
Tidskriftsartikel (refereegranskat)abstract
- Amorphous silicon (a-Si) has gained its popularity in thin film Solar cell fabrication for its high absorption coefficient, high applicability on flexible substrates and practical feasibility for low-cost roll-to-roll mass fabrication. Working as the intrinsic layer, the optical-electrical characteristics of amorphous silicon film is crucial to the cell performance. In this work, the amorphous silicon film has been fabricated on PET substrate by magnetron sputtering method. The main optical-electrical characteristics have been systematically investigated under different fabrication conditions (sputtering power, working pressure, working temperature). The results indicate that the deposition rate increases remarkably from 1.88 to 834 nm/min with the sputtering power increasing from 60 W to 120 W, while the light transmission rate decreases from 86% to 46% in the visible spectrum range (390 nm to 780 nm). Theoretical calculations have been carried out, showing a decreasing deposition rate under an increasing working pressure. A rising temperature provides a higher deposition rate and lower trans-mittance in the certain range. The optimized processing parameters in the fabrication of amorphous silicon thin film are obtained for high photoelectric property on flexible substrates.
|
|
| 6. |
- Liu, Kun, et al.
(författare)
-
B-Doped Amorphous Silicon Thin Films Deposited on Flexible PET Substrate by Magnetron Sputtering
- 2015
-
Ingår i: Journal of Computational and Theoretical Nanoscience. - : American Scientific Publishers. - 1546-1955 .- 1546-1963. ; 12:9, s. 2931-2936
-
Tidskriftsartikel (refereegranskat)abstract
- Depositing amorphous silicon doped with different elements on flexible substrates offers a large potential for the roll-to-roll processes lowering the manufacturing cost of solar cells. Unique magnetron sputtering method was adopted to deposit B-doped amorphous silicon thin film on flexible PET substrate instead of solid substrate materials like glass, metal and silicon. Effects of different substrates were investigated, as well as the processing parameters including sputtering power and working pressure. The structure and performance of the samples were characterized with SEM, XRD, surface profile meter and UV-spectrophotometer. The comparison between PET and glass shows that the alternative of PET substrate significantly improved the deposition rate. Optimal results were obtained as pressure of 0.2 Pa and RF power of 120 W, which showed the lowest transmittance as well as a minimum optical band gap, both are of great significance to photovoltaic conversion. Theoretical justification and experimental data including the feasible magnetron sputtering way, PET flexible substrate and optimized process parameters to the mass production of cheap and high performance heterojunction thin film solar cells were achieved.
|
|
| 7. |
- Liu, L., et al.
(författare)
-
Forecasting Power Output of Photovoltaic System Using A BP Network Method
- 2017
-
Ingår i: Energy Procedia. - : Elsevier Ltd. - 1876-6102. ; 142, s. 780-786
-
Tidskriftsartikel (refereegranskat)abstract
- The characteristics of intermittent and stochastic of solar energy has brought great challenges to power grid system in terms of operation and regulation. Power forecasting is an important factor for optimal schedule of power grid system and assessing the working performance of PV systems. In order to forecast the power output of a PV system located in Ashland at 24-hour-ahead for higher efficiency, a back propagation (BP) neural network model is proposed. Before designing the model, correlation analysis is done to investigate the relationship between power output and solar irradiance and ambient temperature, which are key parameters affecting the power output of PV systems. Based on a correlation analysis, the model admitted the following input parameters: hourly solar radiation intensity, the highest, the lowest daily and the average daily temperature, and hourly power output of the PV system. The output of the model is the forecasted PV power output 24 hours ahead. Based on the datasets, the neural network is trained to improve its accuracy. The best performance is obtained with the BP neural network structure of 28-20-11. The analysis of the error indicator MAPE shows that the proposed model has great accuracy and efficiency for forecasting the power output of photovoltaic systems.
|
|
| 8. |
- Liu, Linan, et al.
(författare)
-
Silicon Effects on Biomass Carbon and Phytolith-Occluded Carbon in Grasslands Under High-Salinity Conditions
- 2020
-
Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 11, s. 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- Changes in climate and land use are causing grasslands to suffer increasingly fromabiotic stresses, including soil salinization. Silicon (Si) amendment has been frequentlyproposed to improve plant resistance to multiple biotic and abiotic stresses and increaseecosystem productivity while controlling the biogeochemical carbon (C) cycle. However,the effects of Si on plant C distribution and accumulation in salt-suffering grasslandsare still unclear. In this study, we investigated how salt ions affected major elementalcomposition in plants and whether Si enhanced biomass C accumulation in grasslandspecies in situ. In samples from the margins of salt lakes, our results showed that thediffering distance away from the shore resulted in distinctive phytocoenosis, includinghalophytes and moderately salt-tolerant grasses, which are closely related to changingsoil properties. Different salinity (NaC/KC, ranging from 0.02 to 11.8) in plants causednegative effects on plant C content that decreased from 53.9 to 29.2% with theincrease in salinity. Plant Si storage [0.02–2.29 g Si m?2 dry weight (dw)] and plantSi content (0.53 to 2.58%) were positively correlated with bioavailable Si in soils(ranging from 94.4 to 192 mg kg?1). Although C contents in plants and phytoliths werenegatively correlated with plant Si content, biomass C accumulation (1.90–83.5 g Cm?2 dw) increased due to the increase of Si storage in plants. Plant phytolith-occludedcarbon (PhytOC) increased from 0.07 to 0.28h of dry mass with the increase of Sicontent in moderately salt-tolerant grasses. This study demonstrates the potential ofSi in mediating plant salinity and C assimilation, providing a reference for potentialmanipulation of long-term C sequestration via PhytOC production and biomass Caccumulation in Si-accumulator dominated grasslands.
|
|
| 9. |
- Liu, Zhan, et al.
(författare)
-
Thermodynamic analysis on the feasibility of a liquid energy storage system using CO2-based mixture as the working fluid
- 2022
-
Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 238
-
Tidskriftsartikel (refereegranskat)abstract
- Pioneering investigation is conducted on the feasibility of designing novel liquid energy storage system by using working fluid blending CO2 with organic fluids to address the condensation problem of subcritical CO2. Organic substances are cautiously screened according to the criteria of environment effect, temperature glide, critical temperature and flammability of working fluid as well as the system performance. Mathematical model of the system is built for thermodynamic examination. An in-house code is developed to complete the system simulations combing with REFPROP subroutine. Results demonstrate that compared to the system with pure CO2, the system with mixture produces an improvement of net power output and energy density and a reduction of charge pressure at an expense of slightly decreasing round trip efficiency. The payment of 6.45 % for round trip efficiency can reduce 55.59 % of charge pressure by taking CO2/R32 as an instance. The system round trip efficiency, energy density and charge pressure decrease with the increase in organic fluid composition. An optimal compression ratio can be identified to reach a maximal round trip efficiency for all mixtures. The cooler outlet temperature is suggested being at the critical temperature of working fluid to reach better system performance.
|
|
| 10. |
- Song, Zhaoliang, et al.
(författare)
-
High potential of stable carbon sequestration in phytoliths of China's grasslands
- 2022
-
Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 28:8, s. 2736-2750
-
Tidskriftsartikel (refereegranskat)abstract
- Phytolith carbon (C) sequestration plays a key role in mitigating global climate change at a centennial to millennial time scale. However, previous estimates of phytolith-occluded carbon (PhytOC) storage and potential in China's grasslands have large uncertainties mainly due to multiple data sources. This contributes to the uncertainty in predicting long-term C sequestration in terrestrial ecosystems using Earth System Models. In this study, we carried out an intensive field investigation (79 sites, 237 soil profiles [0-100 cm], and 61 vegetation assessments) to quantify PhytOC storage in China's grasslands and to better explore the biogeographical patterns and influencing factors. Generally, PhytOC production flux and soil PhytOC density in both the Tibetan Plateau and the Inner Mongolian Plateau had a decreasing trend from the Northeast to the Southwest. The aboveground PhytOC production rate in China's grassland was 0.48 x 10(6) t CO2 a(-1), and the soil PhytOC storage was 383 x 10(6) t CO2. About 45% of soil PhytOC was stored in the deep soil layers (50-100 cm), highlighting the importance of deep soil layers for C stock assessments. Importantly, the Tibetan Plateau had the greatest contribution (more than 70%) to the PhytOC storage in China's grasslands. The results of multiple regression analysis indicated that altitude and soil texture significantly influenced the spatial distribution of soil PhytOC, explaining 78.1% of the total variation. Soil phytolith turnover time in China's grasslands was mainly controlled by climatic conditions, with the turnover time on the Tibetan Plateau being significantly longer than that on the Inner Mongolian Plateau. Our results offer more accurate estimates of the potential for phytolith C sequestration from ecological restoration projects in degraded grassland ecosystems. These estimates are essential to parameterizing and validating global C models.
|
|
