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Timely diagnosis of apple tree nutrition is very important for efficient utilization of nutrients and improvement of apple yield and quality. This study aims to establish an accurate prediction model of nitrogen (N), phosphorus (P), and potassium (K) contents in apple tree leaves based on canopy hyperspectral reflectance. Two-year field experiments with four levels of N application were conducted in 2018 and 2019. The data, including canopy scale hyperspectral reflectance and leaf N, P, and K contents, were collected from young fruit stage to fruit enlargement stage. The stacked ensemble model was applied to build prediction model. The extreme learning machine (ELM) optimized by differential evolution (DE) or self-adaptive differential evolution (SaDE) algorithm and the unoptimized ELM were used to build sub-models, and the weighting strategy based on RMSE or partial least squares (PLS) was applied to combine the sub-models. Results showed that, the stacked ensemble model based on optimized ELM had achieved better prediction results, but the results of model optimized by DE algorithm were prone to over fitting. In the sub-model combination process, PLS could provide the optimal weigh to combine sub-models and correct the over fitting problem. The stacked ensemble SaDE_ELM and PLS (SE-SaDE_ELM-PLS) method for predicting N, P, K contents in apple tree leaves had achieved the best results (N, R2P = 0.844, RMSEP = 1.709 g kg−1, RRMSE = 7.654%; P, R2P = 0.931, RMSEP = 0.137 g kg−1, RRMSE = 6.402%; K, R2P = 0.725, RMSEP = 1.071 g kg−1, RRMSE = 8.747%). The SE-SaDE_ELM-PLS method was reliable for in-situ prediction of N, P, and K contents in apple tree leaves.

Since entering the new era, China's socialist contradiction has been transformed into the contradiction between the people's growing need for a better life and the unbalanced and inadequate development. How to improve the quality of people's life through the improvement of air quality has become an important content restricting social development and a key problem to be solved. Based on the life satisfaction (LS) method, this study takes air quality into the individual utility function, and through matching China Health and Retirement Longitudinal Study (CHARLS), two phases of microindividual tracking data with 122 urban environmental quality data innovatively investigate the impact of air quality on residents' LS and its income substitution effect. The results show that air quality significantly reduces residents' LS, among which, different air pollutants and comprehensive air quality AQI have significant negative effects. And PM10 has the highest marginal effect on different LS evaluation, SO2 has the smallest marginal effect, and AQI marginal effect is close to PM10. In terms of group heterogeneity, NO2 and SO2 have group influence differences in age group, regional economic group, gender group, and family per capita income group. But PM10 and AQI do not show group influence heterogeneity, and air quality has significant negative effect on LS of different groups. In addition, the interaction between air quality and income level shows that air quality strengthens the difference of residents' LS caused by income level difference. According to the equilibrium condition of residents' individual utility function, the improvement of air quality by 1% is equivalent to the improvement of residents' LS by 23.4402% of income. Firstly, air quality has an important impact on residents' LS, and different air pollutants have different effects. Secondly, the impact of air quality on LS of different groups is heterogeneous and mainly diversified in age group, regional economic group, gender group, and family per capital income group. Finally, there is substitution effect between air quality and regional GDP growth and household income, which affects residents' LS. Thirdly, the conclusion shows that the improvement of air quality is difficult to be replaced by other ways. Good air quality can not only directly improve residents' LS, but also has economic effect.

Food waste is a major issue in the context of pollution, climate change, and the future circular economy. Composting kitchen waste is a promising method to recycle elements, yet the efficiency of composting is limited, calling for new processes that degrade rapidly and thoroughly organic matter. Here, we built a rapid laboratory-scale aerobic composting system, equipped with a water bath fueled with either solar energy, or electricity under low sunlight. We tested compositing with and without energy. Results show that only three days are needed to raise the temperature to over 45 °C by energy composting in winter, leading to notable increases in pH, total nitrogen, and cation exchange capacity after 7 days. Composting materials were thoroughly decomposed and mature in 10 days, displaying pH of 7.5, ratio of total organic carbon to total nitrogen of 9.9, cation exchange capacity of 65.61 cmol kg−1, and germination index of 80.4%. Overall, energy composting starts biodegradation quickly in 2 days, reduces effectively the inhibition from some waste compounds, decomposes organic substances well, and yields mature compost.

We investigated the dynamics and factors influencing the N uptake capacity in two sub-root systems of maize seedlings under partial N stress. Maize seedlings were grown in split-root containers containing nutrient solutions. Two N application conditions prior to partial N stress (full-strength N (4.0 mM): CP; N stress: SP) were considered. Thus, two experiments were conducted: (A) four treatments: CPNc, CPN2, CPN1 and CPN0, in which half of the root system was exposed to 4.0 mM, 2 mM, 1 mM and 0 mM N (CPNc–c, CPN2–2, CPN1–1 and CPN0–0), respectively, and the other half received full-strength N (CPNc–c, CPN2–c, CPN1–c and CPN0–c); (B) four treatments: SPNc, SPN2, SPN1 and SPN0, in which both sub-root systems received 4.0 mM, 2 mM, 1 mM and 0 mM N for 6 days, respectively, after which half of the root system was maintained at original N level (SPNc–c, SPN2–2, SPN1–1 and SPN0–0) and the other half received full-strength N (SPNc–c, SPN2–c, SPN1–c and SPN0–c). At 0.25 days after treatment (DAT), CPN2–c and CPN1–c enhanced N inflow rates (Iroot), whereas CPN0–c decreased it by 27.3% compared with CPNc–c, Iroot in CPN2–c, CPN1–c and CPN0–c was uniformly enhanced at 1 DAT, but were only enhanced in CPN0–c at 5 DAT compared with CPNc–c. In contrast, SPN1–c had a significantly increased Iroot by 10.52% compared with SPNc–c, although other treatments showed a negative effect on Iroot at 0.25 DAT. At 1 and 5 DAT, Iroot in SPN2–c, SPN2–2, SPN1–c, SPN1–1 and SPN0–c were significantly lower than that in SPNc–c. Furthermore, CP significantly enhanced Iroot in non-stressed sub-roots compared with SP. Additionally, CPN2 improved shoot dry mass and N use efficiency even under SPN2. Thus, N uptake capacity in each sub-root zone varied not only depending on the severity and duration of the N stress, but was also related to the N status prior to partial N stress. Moreover, the occurrence and disappearance of the root compensatory effect were delayed with increasing N stress severity. A higher compensatory effect developed following CP, even under CPN0.

To understand the functions of Populus euphratica CPD (PeCPD) and DWF4 (PeDWF4), the responses to exogenous phytohormone in Arabidopsis-PeCPD and -PeDWF4 transgenic lines (PeCPD-TL and PeDWF4-TL) and corresponding wild type (WT) seedlings were investigated. Results showed that all of PeCPD-TL, PeDWF4-TL and WT seedlings cultured on the mediums containing 2,4-dichlorophenoxyacetic acid (2,4-D) + 6-benzylaminopurin (6-BA) or 2,4-D + 6-BA + brassinolide (BL) could be dedifferentiated to callus with 100% frequency, but they displayed strong differences in callus formation sites, callus growth rates (CGRs) and tissue dedifferentiation degrees. On the medium containing 2,4-D alone, the seedlings of all the plants could formed callus, but callus formation times (CFTs) were delayed, and callus formation rates (CFRs) were differentially decreased. After adding lower concentrations of BL, their CFRs were all restored to 100%, but tissue dedifferentiation degrees were obviously lower than these on the mediums with 2,4-D + 6-BA or 2,4-D + 6-BA + BL. On the mediums containing 6-BA or 6-BA + BL, the seedlings of all the plants failed to produce callus. Semi-quantitative RT-PCR analysis also showed that the transcription levels of PeCPD, PeDWF4, AtCPD and AtDWF4 in PeCPD-TL, PeDWF4-TL and WT were evidently different. These results suggest that PeCPD and PeDWF4 play similar but not exactly the same roles in the regulation of callus morphogenesis of Arabidopsis seedlings, and that BL can partially replace the role of cytokinin to induce callus formation through interacting with auxin.

Effects of severity and duration of osmotic stress on partial root system were investigated on root hydraulic conductance (L p ) and growth in each sub-root system. The maize seedlings were raised in nutrient solution with the roots divided equally into two containers. At 12 days after transplanting, half of root system was subjected to osmotic stress of −0.2, −0.4 and −0.6 MPa using PEG 6000 added in the solution, and no PEG 6000 solution was taken as control (CK). L p and root growth in each sub-root system were measured at 0, 0.25, 0.5, 1, 3, 5, 7 and 9 days after treatment (DAT). Results show that compared to CK, −0.2 MPa treatment enhanced the hydraulic conductance per root area (L pr ) in non-stressed sub-root system by 12 % at 0.5 DAT. In −0.4 MPa treatment, L pr in non-stressed sub-root system was significantly increased at 9 DAT. But in −0.6 MPa treatment, significant decrease of 12–40 % was observed in non-stressed sub-root system during 0.5–3 DAT if compared to CK, indicating that the threshold of osmotic stress for the compensatory effect of water uptake in non-stressed sub-root system was between −0.2 and −0.4 MPa. In addition, the root area growth rate in non-stressed sub-root system was significantly higher than that in CK during 0.25–0.5, 1–3 and 5–7 DAT for −0.2, −0.4 and −0.6 MPa treatments, respectively. Similar trend also was observed for root length growth rate, indicating that osmotic stress could still stimulate the compensatory effect of root growth other than water uptake under partial root system. Moreover, the occurrence of such compensatory effect delayed with the increasing osmotic stress. Meanwhile, −0.2 MPa treatment had no significant effect on maize shoot growth but −0.4 and −0.6 MPa treatments inhibited shoot biomass accumulation, which resulted in higher root/shoot ratio in −0.4 and −0.6 MPa treatments. Thus root plasticity in hydraulic conductance and root growth in different root zones varied largely depending on the severity and duration of osmotic stress under partial root system.

In 2001, a construction campaign regarding wastewater treatment plants (WWTPs) occurred in China. Unfortunately, the treatment has not yet achieved anticipated effectiveness. A critical reason for this is that the influent chemical oxygen demand (COD) and biochemical oxygen demand (BOD) concentrations in WWTPs are unacceptably low. This paper indicates that a fundamental, but commonly overlooked contributing factor to this problem is that a large portion of easily degradable COD and BOD is degraded prematurely before entering municipal sewers, and this is directly correlated to China's standards for pollutant discharging into municipal sewers. This perspective is further unfolded through retrospection of the history of Chinese wastewater treatment and the investigation of standards among developed zones and districts. This paper suggests that in China, the standards for pollutant discharging into municipal sewers should be relaxed. Meanwhile, unnecessary pretreatment of COD and BOD should cease for the purpose of ensuring that easily degradable COD and BOD can be transferred to WWTPs to improve treatment efficiency. Moreover, additional alternatives are presented to resolve this problem.

In this paper, we studied the VOPO4·2H2O as an electrode material for supercapacitors. A systematic comparison of VOPO4·2H2O prepared by reflux and hydrothermal methods was carried out through detailed analyses that included power X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Their electrochemical performances were also investigated by using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Meanwhile, we proposed a possible charge storage mechanism on the VOPO4·2H2O electrode surface. The material synthesized by reflux method had better performance in the capacitance than that by hydrothermal method, and its specific capacitance was up to 202 F/g at 2 mV/s. A total of 67.4 % of capacitance was maintained for the VOPO4·2H2O synthesized by reflux method when current density changed from 0.2 to 2 A/g, much higher than those obtained from the hydrothermal-synthesized VOPO4·2H2O supercapacitor of 42.5 %. The energy density of VOPO4·2H2O supercapacitor synthesized by reflux method was 18.7 Wh/kg at 290 W/kg and maintained 6.2 Wh/kg at 1,421 W/kg, much higher than the hydrothermal-synthesized VOPO4·2H2O supercapacitor. Our work confirms that VOPO4·2H2O is a potential electrode material for supercapacitors.