Solar absorber is a key device that converts solar irradiation into heat via photothermal conversion, which has potential applications in solar thermal power systems, and seawater desalination. In ...this paper, we propose a wide-angle, broadband and polarization insensitivity metamaterial solar absorber based on titanium nitride (TiN). Numerical results show that this solar absorber has a total average spectrum absorption of up to 97.5% at wavelength of 300–2500 nm. Based on the distributions of the electric and magnetic field, it is believed that the coupling resonance of surface plasmon resonance, guided mode resonance and cavity resonance is responsible for its excellent absorption of solar energy. Furthermore, we discuss the effects of incidence angle on the solar absorber and demonstrate that the average spectrum absorption of more than 85% can be obtained even at a large incidence angle of 60°, and it is insensitive to the change of polarization angle. The effect of geometric parameters of the solar absorber on spectrum absorption performance was investigated. This research will provide new ideas for the design of solar thermophotovoltaic and thermal conversion systems.
Solar absorber is the key component to realize efficient utilization of solar energy. In this paper, only titanium nitride (TiN) is used to create a broadband, wide-angle, polarization insensitivity ...solar absorber. The average absorption of the absorber in the spectral range of 300-2500 nm is 91.3%. The distributions of electric and magnetic fields indicate that the strong absorption is caused by the coupling effect of surface plasmon resonance and guided mode resonance. Investigate the effects of the geometric parameters of the absorber on the spectral absorption performance. Moreover, we also discuss the absorption performance of the solar absorber at different incidence angles. It is demonstrated that even at a large incidence angle of 60°, the average spectral absorption can exceed more than 70%. The proposed solar energy absorber is also insensitive to polarization. The research results in this work could benefit the applications in solar thermophotovoltaic system.
Several long non-coding RNAs (lncRNAs) have been associated with cell senescence, termed senescence-associated lncRNAs (SAL-RNAs). However, the mechanisms involved for SAL-RNAs in aging are not fully ...elucidated. In the present study, we investigated the effects of SAL-RNAs on aged human bone marrow-derived mesenchymal stem cells (hBM-MSCs), and the possible means to counteract such effects to improve the regenerative capacity of aged hBM-MSCs.
By comparing the lncRNAs expression of hBM-MSCs derived from young and old individuals, lnc-CYP7A1-1 was identified as being significantly increased with age. Using predictive software, the expression of Spectrin Repeat Containing Nuclear Envelope Protein 1 (SYNE1), was found to be decreased with age. Next, through lentiviral constructs, we downregulated the expression of lnc-CYP7A1-1 or SYNE1 in hBM-MSCs separately. Additionally, hBM-MSCs proliferation, survival, migration, and senescence were investigated
, lnc-CYP7A1-1 downregulated aged hBM-MSCs were implanted into infarcted mouse hearts after myocardial infarction (MI), and cardiac function was measured. Through lentivirus-mediated downregulation of lnc-CYP7A1-1 in aged hBM-MSCs, we revealed that cell senescence was decreased, whereas cell proliferation, migration, and survival were increased. On the other hand, downregulation of SYNE1, the target gene of lnc-CYP7A1-1, in young hBM-MSCs increased cell senescence, yet decreased cell proliferation, migration, and survival. Downregulation of lnc-CYP7A1-1 in aged hBM-MSCs induced cell rejuvenation, yet this effect was attenuated by repression of SYNE1.
, transplantation of lnc-CYP7A1-1 downregulated old hBM-MSCs improved cardiac function after MI.
Down-regulation of lnc-CYP7A1-1 rejuvenated aged hBM-MSCs and improved cardiac function when implanted into the infarcted mouse hearts, possibly through its target gene SYNE1.
Application of organic manure combined with synthetic fertilizer can maintain crop yield and improve soil fertility, but the long-term effects of substituting different proportions of synthetic ...fertilizers with organic manure on N2O emission remain unclear. In this study, field experiments and DNDC model simulations were used to study the long-term effects of substituting synthetic fertilizers with organic manure on crop yield and N2O emission. The field experiment was conducted at Guanzhong Plain, northern China, under a wheat-maize cropping system. Six treatments were included: no fertilization (CK); synthetic nitrogen (N), phosphorus (P) and potassium (K) fertilizers (NPK); and 25%, 50%, 75% and 100% of the synthetic N substituted by dairy manure (25%M, 50%M, 75%M, and 100%M), respectively. The DNDC model was calibrated using the field data from the NPK treatment from 2014 to 2017 and was validated for the other treatments. The results showed that the DNDC model can successfully simulate the crop yield (e.g. nRMSE < 5%) and annual N2O emission (nRMSE < 20%). In addition, a 30-year simulation found that organic manure substitution treatments could maintain wheat yield well, and the yield variation between different years was small. However, relative to the NPK treatment, the maize yields for the first 6 and 7 years were lower under 50%M and 75%M, and under 100%M maize yields were reduced for the first 15 years. The long-term simulation showed that N2O emission of fertilized treatment had an increasing trend over time, especially the 75%M treatment where the N2O emission was higher than that of NPK treatment after 25 years of fertilization. The annual mean N2O emission under different treatments was, in decreasing order, NPK > 25%M > 50%M > 75%M > 100%M > CK. The yield-scale N2O emission and emission factor were highest for the NPK treatment. Considering crop yield, yield stability and N2O emission, substitution of 25% synthetic fertilizer by organic manure can simultaneously ensure crop productivity and environmental protection under the tested environment.
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•DNDC model can successfully simulate crop yield and N2O emission under wheat-maize.•Organic manure addition had lower N2O emission than using mineral fertilizers alone.•Organic manure replacing 25% mineral fertilizer gets good yield and low N2O emission.
Solar thermophotovoltaic systems are capable of showing efficient photoelectric conversion and are expected to surpass the ShockleyQueisser limit, owing to the spectrum-selective functionality of ...metamaterial selective emitters. Generally, metamaterial emitters are manufactured from multifarious materials, which also makes their manufacturing process complicated. Here, we propose a tungsten-only emitter composed of two rectangular bars with different widths and heights arranged in a cruciform structure, featuring a rectangular cavity at the top. Results from the simulations reveal that the emissivity of the metamaterial emitter exceeds 90% at the wavelength of 9501590 nm and drops below 20% for wavelengths exceeding 2025 nm, which can effectively match GaSb photovoltaic cells. The outstanding emission performance is attributed to the coupling effect of surface plasmon resonance, cavity resonance and guided mode resonance, as evidenced by the analysis of electric and magnetic fields. We also explored the radiation spectrum in the 5002500 K temperature range and found that it performed best at 1400 K. It is concluded that the emission performance is slightly affected by structural parameters and angles. This study presents a meaningful exploration of efficient solar utilization.
We propose a tungsten-only emitter with over 90% emissivity in the wavelength range of 9501590 nm and lower emissivity in the wavelength range exceeding 2000 nm, which can effectively match GaSb cells for thermoelectric conversion.
Measuring the indoor temperature of building rooms is a valuable approach for evaluating thermal comfort and providing feedback control for heat substations in district heating systems (DHSs) in ...China. Previous studies on indoor temperatures have primarily focused on analyzing their overall trends and influencing factors, while research on daily change patterns is lacking. This study utilized a clustering method to analyze the indoor temperature data from an actual DHS in Northeast China. First, a 24-h observation vector was constructed using the deviation between the actual and target values to represent the daily temperature pattern. Second, the k-means method was applied to cluster the values, and the quantity distribution and typical characteristics of each cluster were analyzed. Finally, a multi-nominal logistic regression model was used to analyze the influence of different factors on each cluster. The comparison results with the four representative clustering algorithms indicated that k-means was the optimal model and the optimal number of clusters was 4. The trend of each cluster was roughly the same, with the main difference being the fluctuation amplitude and distance from the target value. The differences between the clusters were related to various influencing features, with the primary return pressure for workdays and the secondary return pressure for holidays being the most significant. This study identified the optimal daily variation patterns of indoor temperature and analyzed the important features that affect this pattern, which is beneficial for enhancing the regulatory efficiency of DHS.
•Deviation-based observation vector represents daily temperature patterns.•Cluster analysis uncovers distinct patterns in daily indoor temperature change.•Optimal clustering effectiveness is achieved using k-means (DBI = 0.63).•Significant differences observed among clusters through varied characteristics.•MNLogit used to assess influence degrees of different features on clusters.
Application of organic manure combined with synthetic fertilizer can maintain crop yield and improve soil fertility, but the long-term effects of substituting different proportions of synthetic ...fertilizers with organic manure on N
O emission remain unclear. In this study, field experiments and DNDC model simulations were used to study the long-term effects of substituting synthetic fertilizers with organic manure on crop yield and N
O emission. The field experiment was conducted at Guanzhong Plain, northern China, under a wheat-maize cropping system. Six treatments were included: no fertilization (CK); synthetic nitrogen (N), phosphorus (P) and potassium (K) fertilizers (NPK); and 25%, 50%, 75% and 100% of the synthetic N substituted by dairy manure (25%M, 50%M, 75%M, and 100%M), respectively. The DNDC model was calibrated using the field data from the NPK treatment from 2014 to 2017 and was validated for the other treatments. The results showed that the DNDC model can successfully simulate the crop yield (e.g. nRMSE < 5%) and annual N
O emission (nRMSE < 20%). In addition, a 30-year simulation found that organic manure substitution treatments could maintain wheat yield well, and the yield variation between different years was small. However, relative to the NPK treatment, the maize yields for the first 6 and 7 years were lower under 50%M and 75%M, and under 100%M maize yields were reduced for the first 15 years. The long-term simulation showed that N
O emission of fertilized treatment had an increasing trend over time, especially the 75%M treatment where the N
O emission was higher than that of NPK treatment after 25 years of fertilization. The annual mean N
O emission under different treatments was, in decreasing order, NPK > 25%M > 50%M > 75%M > 100%M > CK. The yield-scale N
O emission and emission factor were highest for the NPK treatment. Considering crop yield, yield stability and N
O emission, substitution of 25% synthetic fertilizer by organic manure can simultaneously ensure crop productivity and environmental protection under the tested environment.
Soil moisture is one of the important factors affecting the growth of crops. Accurate monitoring and forecasting of soil moisture in the growth period of crops is an important part of agricultural ...production. In this study, 15 predictors from three aspects of meteorology, topography and soil properties in Baoji were selected to establish the machine learning model to predict the soil moisture in 0~20cm and 20~40cm soil layers. The prediction of same data was carried out by three models, which were support vector machine (SVM), random forest (RF) and back-propagation neural network (BPNN). The results showed that the prediction accuracy of SVM were 92.899% and 92.656% in 0~20cm and 20~40cm soil layers, the RMSE were 7.521 and 8.011 respectively, while the RF were 87.632% and 87.842% in prediction accuracy, 10.759 and 11.042 in RMSE, and the prediction accuracy of BPNN were 80.570% and 85.323%, the RMSE were 12.147 and 11.165. The study found that the three models have good prediction effect on winter wheat soil moisture in Baoji, reflecting the good application ability of machine learning model in soil moisture prediction. And the prediction accuracy of three models in 0~20cm soil layer were slightly better than that in 20~40cm. Compared with the model of RF and BP, SVM has better prediction results. And the analysis of predictors showed that the meteorology has greatest impact on soil moisture and its changes, which the precipitation, air relative humidity and sunshine duration most; the effects of topography is relative, which the slope and elevation have great influence; soil property has little effect on the change of soil moisture, which the thickness of plough layers has slightly stronger influence than other factors.
Band gap, which can be tuned by changing the size of quantum dots （QDs） based on the quantum confinement effect, plays a fundamental role in electrical and optical properties of QDs. However, the ...tuning of the band gap by changing the size results in a series of intrinsic problems, such as the instability of the extremely small QDs, negative combination with biomolecules because of the large size of QDs, etc. Recently, several new methods have been developed to further study and improve the tuning of the band gap. In this paper, we summarized the recent progress in the fields of tuning the band gap of QDs, including alloyed QDs, core-shell QDs and doped QDs. The review has also prospected the development trend of tuning the band gap as well as their applications.
In this study, we used insulin-like growth factor-1 to induce bone marrow mesenchymal stem cells （MSCs） to differentiate into oligodendrocyte-like cells. Cell surface marker identification showed ...that they expressed myelin basic protein and galactosylceramide, two specific markers of oligodendrocytes. These cells were transplanted into rats with acute spinal cord injury at Tt0. At 8 weeks post-implantation, oligodendrocyte-like cells were observed to have survived at the injury site The critical angle of the inclined plane, and Basso, Beattie and Bresnahan scores were all increased. Furthermore, latencies of motion-evoked and somatosensory-evoked potentials were decreased. These results demonstrate that transplantation of oligodendrocytic-induced MSCs promote functional recovery of injured spinal cord.
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