Compared with traditional thermoelectric materials, layered oxyselenide thermoelectric materials consist of nontoxic and lower-cost elements and have better chemical and thermal stability. Recently, ...several studies on n-type layered oxyselenide thermoelectric materials, including BiCuSeO, Bi2O2Se and Bi6Cu2Se4O6, were reported, which stimulates us to comprehensively summarize these researches. In this short review, we begin with various attempts to realize an n-type BiCuSeO system. Then, we summarize several methods to optimize the thermoelectric performance of Bi2O2Se, including carrier engineering, band engineering, microstructure design, et al. Next, we introduce a new type of layered oxyselenide Bi6Cu2Se4O6, and n-type transport properties can be obtained through halogen doping. At last, we propose some possible research directions for n-type layered oxyselenide thermoelectric materials.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The aim of the present study was to investigate the efficacy of oral administration of probiotic Lactobacillus casei Shirota and amoxicillin-sulbactam in treating childhood fast breathing pneumonia. ...518 children diagnosed of fast breathing pneumonia were enrolled and randomly assigned to be administered either amoxicillin-sulbactam + Lactobacillus casei Shirota or amoxicillin-sulbactam + placebo. Primary outcome was defined as treatment failure before day 3, and secondary outcome was defined as treatment failure during follow-ups on day 6 and 12. Serum levels of tumor necrosis factor-α and interferon-γ were also examined at the end of day 3. Treatment failure rate before day 3 was significantly reduced in amoxicillin-sulbactam + Lactobacillus casei Shirota group compared to amoxicillin-sulbactam + placebo group. Serum levels of tumor necrosis factor-α and interferon-γ were both significantly reduced in amoxicillin-sulbactam + placebo group on day 3. On day 6 and 12, although treatment failure rates were higher than on day 3 in both groups, it was still significantly reduced in amoxicillin-sulbactam + Lactobacillus casei Shirota group. No severe adverse effects were observed in either treatment group. In conclusion, Probiotic Lactobacillus casei Shirota, in combination with amoxicillin-sulbactam, is more effective in treating childhood fast breathing pneumonia, which supports the potential clinical application of Lactobacillus casei Shirota as a safe supplement to amoxicillin-sulbactam therapy against childhood fast breathing pneumonia.
The utility-scale deployment of photovoltaic (PV) power plants is critical for achieving carbon peaking and carbon neutrality goals and mitigating climate change. However, the impact of a PV power ...plant project on the microclimate is unclear for different underlying surfaces. Therefore, PV power plants in deserts and lakes were selected to assess and compare the impact of PV array deployment on the environment by the observation. The results indicate that the PV array affected the wind pattern, the wind direction makes simple (from 10 m to 2 m), and wind speed in the PV site under two types of underlying surfaces was less than the reference site. For the PV power plant in desert, the delta (PV - REF) is increased from 0.12 m s−1 at 10 m to 0.27 m s−1 at 2 m. The counterpart in the lake is increased from 0.14 m s−1 at 10 m to 0.55 m s−1 at 2 m. However, the PV arrays had no effect on the air temperature at the center of the PV array gap. The difference in air temperature for two observation sites under two type of underlying surfaces was less than the resolution of instrument MaxiMet (0.1 °C). Instead, the heat from the PV panels is transmitted down to the land surface, causing a temperature effect in the desert and lakes. For the PV power plant in land, the arrays have heating effect on air temperature (The air temperature was 33.43 °C in the PV_land site, and 28.03 °C in the REF_land site in July, respectively). But the arrays have cooling effect on air temperature for the PV power plant in lake in the same month (PV_lake site, 28.58 °C; REF_lake site, 29.97 °C). Furthermore, evaporation is lower in the PV power plant owing to the physical shielding of PV arrays (For the land, the peak of hour evaporation (PV_land – REF_land) was 0.12 mm; for the lake, the peak of hour evaporation (PV_lake – REF_lake) was 0.32 mm). This study provides new evidence of the microclimate impact of photovoltaic array deployment on different underlying surfaces.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Accumulating evidence demonstrates that there is a causative link between hsa-microRNA-9-5p (miR-9) and pathophysiological processes. Enterovirus 71 (EV71) has been found to contribute to numerous ...severe clinical symptoms which result in death. The exact mechanism by which EV71 influences miR-9 expression is unknown, and the relationship between miR-9 and EV71 is still unclear. Here, miR-9 expression was found to be impaired upon EV71 infection in several cell lines and in an EV71 infection mouse model. Additionally, we confirmed that EV71 infection induces robust expression of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1) and interferons (IFN-α and IFN-β). Overexpression of miR-9 attenuated EV71 proliferation and reduced protein and gene expressions of virion protein 1 (VP1) of EV71. Furthermore, we observed that the inflammation caused by EV71 infection was restored to a moderate level via miR-9 overexpression. Nuclear factor kappa B (NFκB) in the retinoic acid-induced gene 1 (RIG-I) signaling pathway, but not interferon regulating factor 3 (IRF3), was significantly decreased and inactivated by ectopic miR-9 expression. Moreover, in mouse infection experiments, administration of miR-9 agomirs caused a significant decrease in VP1 levels and pro-inflammatory cytokine production after viral inoculation. Taken together, the present data demonstrate that miR-9 exerts an anti-EV71 effect in cells and a mouse model via mediating NFκB activity of the RIG-I signal pathway, thereby suggesting a new candidate for antiviral drug development.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Evapotranspiration (ET) is the major component of the hydrology cycle. Satellites provide a convenient way for gathering information to estimate regional ET. The most widely applied method for ...converting the instantaneous satellite measurement to daily scale assumes that evaporative fraction (EF), defined as the ratio of ET to the available energy, is constant during the daytime. However, this method was proved to underestimate the daily ET. This study implemented a theoretically improved EF algorithm to calculate daily ET with the decoupling factor method based on the Penman‐Monteith and McNaughton‐Jarvis equations. Seven improved algorithms were developed by assuming that various parameters remain constant during the day. The satellite‐based ET estimates were compared with seven local flux tower measurements in China. The results showed that: (a) The original ET method calculated the daily evaporation more accurately than the other algorithms. However, the good fit was based on two compensating inaccuracies. Compared to the flux tower measurement, the original ET method underestimated the daily EF by 26% and overestimated the daily net radiation by 30%. (b) Six of the seven proposed algorithms underpredicted the daily ET by 30%–60%, mainly due to the inaccurate daily net radiation. (c) The algorithm that assumed that the instantaneous decoupling parameter Ω∗ was equal to its daily value method calculated EF and ET with relative errors of 8% and 10% separately when the inaccurate estimated daily net radiation was replaced by the observed flux tower data.
Plain Language Summary
The water that evaporates from the land surface sustains the hydrological cycle that replenishes the world's freshwater resources. Scientists and water managers are therefore interested in quantifying the water that evaporates each day. It is especially true for China that has one of the lowest water reserves in the world. Satellites that provide coverage of all the land surface would be ideal for recording evaporation if we could scale up the instantaneous satellite measurements to a daily scale. The current scale‐up methods available have not been widely tested. In this manuscript, we test the available methods and show how they can be improved for China.
Key Points
This article improved satellite‐based daily evapotranspiration calculations for China
A decoupling parameter method was used in the daily evaporation fraction algorithm
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Compared with p-type oxyselenide thermoelectric material, the corresponding n-type material research progress is slow. In this work, combining low thermal conductivity of BiCuSeO and high electron ...carrier concentration of n-type Bi2O2Se, a new-type two-dimensional layered oxyselenide Bi6Cu2Se4O6 was synthesized. Through increasing electron carrier concentration via introducing transition metal elements (Ti, Zr, Ce), the electrical transport properties were enhanced and the peak ZT value ~ 0.16 at 873 K was obtained, which is 60 % higher than that in Bi6Cu2Se3.6Cl0.4O6. This work indicates that transition metal element is an effective n-type dopant to enhance the thermoelectric performance of Bi6Cu2Se4O6.
The new-type 2D layered oxyselenide Bi6Cu2Se4O6 can be synthesized by intercalating BiCuSeO and Bi2O2Se layers with a 1:2 ratio along the c-axis. Through introducing transition metal elements, a 60 % improvement of peak ZT value (~ 0.16 at 873 K) can be reached in Bi5.9Zr0.1Cu2Se3.6Cl0.4O6. Display omitted
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Oxygen-containing semiconductors are considered to be promising thermoelectric materials because of the high physicochemical stability. New layered oxyselenide Bi6Cu2Se4O6 possesses intrinsic low ...lattice thermal conductivity and can be modulated to n-type semiconductor through halogen doping, which is considered as a potential n-type thermoelectric oxide. In this work, first-principles calculations are utilized to obtain the electronic and phonon band structures for deeply recognizing the transport features of intrinsic Bi6Cu2Se4O6. Furthermore, Nb is selected as donor dopant in Bi6Cu2Se3.6Cl0.4O6, realizing a significantly improved power factor of ∼ 4.3 μV cm−1 K−2, which originates from the simultaneously optimized carrier concentration by effective doping and strengthened effective mass by inducing resonant levels around Fermi level. Meanwhile, the enhancement of phonon scattering are introduced, leading to a low lattice thermal conductivity of ∼ 0.68 W m−1 K−1. Finally, thanks to the effective doping of Nb and the introduction of resonant levels, a maximum ZT ∼ 0.4 at 873 K and an average ZT ∼ 0.21 from 303 to 873 K can be obtained in n-type Bi5.91Nb0.09Cu2Se3.6Cl0.4O6. This study broadens the applicability of resonant levels to optimize performances of thermoelectric oxides, and promotes the potential application of n-type Bi6Cu2Se4O6-based thermoelectric materials in medium temperature range.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
High carrier mobility is critical to improving thermoelectric performance over a broad temperature range. However, traditional doping inevitably deteriorates carrier mobility. Herein, we develop a ...strategy for fine tuning of defects to improve carrier mobility. To begin, n-type PbTe is created by compensating for the intrinsic Pb vacancy in bare PbTe. Excess Pb2+ reduces vacancy scattering, resulting in a high carrier mobility of ∼3400 cm2 V–1 s–1. Then, excess Ag is introduced to compensate for the remaining intrinsic Pb vacancies. We find that excess Ag exhibits a dynamic doping process with increasing temperatures, increasing both the carrier concentration and carrier mobility throughout a wide temperature range; specifically, an ultrahigh carrier mobility ∼7300 cm2 V–1 s–1 is obtained for Pb1.01Te + 0.002Ag at 300 K. Moreover, the dynamic doping-induced high carrier concentration suppresses the bipolar thermal conductivity at high temperatures. The final step is using iodine to optimize the carrier concentration to ∼1019 cm–3. Ultimately, a maximum ZT value of ∼1.5 and a large average ZT ave value of ∼1.0 at 300–773 K are obtained for Pb1.01Te0.998I0.002 + 0.002Ag. These findings demonstrate that fine tuning of defects with <0.5% impurities can remarkably enhance carrier mobility and improve thermoelectric performance.
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IJS, KILJ, NUK, PNG, UL, UM
Abstract
Heterogeneous composites consisting of Bi
6
Cu
2
Se
3.6
Cl
0.4
O
6
and Bi
2
O
2
Se are prepared according to the concept of modulation doping. With prominently increased carrier mobility and ...almost unchanged effective mass, the electrical transport properties are considerably optimized resulting in a peak power factor ≈1.8 µW cm
−1
K
−2
at 873 K, although the carrier concentration is slightly deteriorated. Meanwhile, the lattice thermal conductivity is lowered to ≈0.62 W m
−1
K
−1
due to the introduction of the second phase. The modified Self‐consistent Effective Medium Theory is utilized to explain the deeper mechanism of modulation doping. The enhancement of apparent carrier mobility is derived from the highly active phase interfaces as fast carrier transport channels, while the reduced apparent thermal conductivity is ascribed to the existence of thermal resistance at the phase interfaces. Ultimately, an optimized
ZT
≈0.23 is obtained at 873 K in Bi
6
Cu
2
Se
3.6
Cl
0.4
O
6
+ 13% Bi
2
O
2
Se. This research demonstrates the effectiveness of modulation doping for optimizing thermoelectric properties once again, and provides the direct microstructure observation and consistent theoretical model calculation to emphasize the role of interface effects in modulation doping, which should be probably applicable to other thermoelectrics.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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