Sodium metal is a promising anode, but uneven Na deposition with a dendrite growth seriously impedes its application. Herein, a fibrous hydroxylated MXene/carbon nanotubes (h‐Ti3C2/CNTs) composite is ...designed as a scaffold for dendrite‐free Na metal electrodes. This composite displays fast Na+/electron transport kinetics and good thermal conductivity and mechanical properties. The h‐Ti3C2 contains abundant sodiophilic functional groups, which play a significant role in inducing homogeneous nucleation of Na. Meanwhile, CNTs provide high tensile strength and ease of film‐forming. As a result, h‐Ti3C2/CNTs exhibit a high average Coulombic efficiency of 99.2 % and no dendrite after 1000 cycles. The h‐Ti3C2/CNTs/Na based symmetric cells show a long lifespan over 4000 h at 1.0 mA cm−2 with a capacity of 1.0 mAh cm−2. Furthermore, Na‐O2 batteries with a h‐Ti3C2/CNTs/Na anode exhibit a low potential gap of 0.11 V after an initial 70 cycles.
A friend to sodium: A fibrous hydroxylated h‐Ti3C2/carbon nanotubes composite is designed as a scaffold for dendrite‐free Na metal electrodes. It displays fast Na+/electron transport kinetics, high sodiophilicity, and satisfactory thermal conductivity and mechanical properties.
•We designed optimal N management with high-yielding drip irrigation under plastic mulch (DIPM) system.•Optimal N management with DIPM system achieves 90% of yield potential.•Optimal N management ...determining following N accumulation is similar to the economically optimal N rate.•The higher post-anthesis biomass and N uptake was crucial for the higher yield with DIPM system.
Drip irrigation under plastic mulch (DIPM) has been used to achieve high maize yields in China, but N use efficiency is often low and N losses are high. Here, we designed a DIPM system with optimal N management to close the maize yield gap with high NUE and low N loss and used it in Northeast China in 2014 and 2015. The amount and timing with optimal N rate (ONR) were designed to close the maize yield gap based on the N requirement. Grain yield using the ONR treatments averaged 13.8Mgha−1 during 2014 and 2015, which was 90% of the yield potential simulated by the Hybrid-Maize Model. When N treatment was less than the ONR (70% ONR), grain yield decreased from 13.8 to 11.6Mgha−1. When additional N fertilizer (130% ONR) was applied, no gain in yield was achieved, but N losses increased significantly from 65 to 121kgNha−1. Grain yield was significantly lower in the farmers’ typical N practice treatment than that in the ONR treatment. Although 30% more N was applied with farmers’ practice, the lowest N use efficiency and greatest N losses were observed. In conclusion, DIPM with optimal N management increased yield potential with high N use efficiency and low N losses in a water-limited region.
Film-mulched drip irrigation has become an important strategy in maize cultivation in the semiarid region of Northeast China. Most farmers concentrate nitrogen (N) fertilizer use early in maize ...growth, which leads to low N use efficiency and large N losses. Therefore, a three-year (2018 to 2020) field experiment was conducted to determine the optimal N management strategy for maize under film mulch with drip irrigation in the semiarid region of Northeast China. The experiment included five treatments with the total amount of N fertilizer (210 kg N ha
) applied in different proportions at sowing, sixth-leaf (V6), twelfth-leaf (V12), tasseling (VT), and blister (R2) stages of maize growth: N1, 100-0-0-0-0; N2, 50-50-0-0-0; N3, 30-50-20-0-0; N4, 20-30-30-20-0; and N5, 10-20-30-20-20. The control (CK) did not receive N fertilizer. Maize yield, N uptake and use, changes in soil inorganic N content, and N balance were investigated. Compared with the single basal application (N1), split-N applications (N2, N3, N4, N5) increased maize yield from 13.8% to 24.5% by increasing kernel number per ear and 1000-kernel weight and also improved N accumulation from VT to physiological maturity (PM) stages and its contribution to grain N uptake. In addition, compared with N1, split-N applications also decreased N losses by increasing inorganic N contents in the 0-40 cm soil layer and by decreasing N leaching in the 60-200 cm soil layer. Regression analysis demonstrated that N accumulation after the VT stage was positively related with maize yield. Among treatments, N4 had the highest yield, N recovery efficiency, agronomic efficiency, and partial factor productivity, with respective increases of 24.5%, 14.7 percentage point, 11.4 kg kg
, and 11.4 kg kg
compared with those in N1. As a result, N losses were also reduced by 33.7% in N4 compared with those in N1. In conclusion, the split-N management strategy with four N applications under film-mulched drip irrigation has great potential to improve maize yield, increase N use efficiency, and reduce N loss in the semiarid region of Northeast China.
•On-farm location experiments and simulation model were combined to test the benefit across three years of the NE system.•Nutrient Expert attained 80% of potential yield, and increased average yield ...by 0.9tha−1 than with farmers’ fertilizer practice.•Nutrient Expert considerably increased nutrient use efficiency than with farmers’ fertilizer practice.•Nutrient Expert decreased total estimated GHG emissions and GHG emission intensity by 17% and 23% than with farmers’ fertilizer practice, respectively.
A science-based, reliable, and feasible fertilizer recommendation method is required to respond to the low nutrient use efficiency caused by inappropriate fertilization practices. Soil test-based fertilizer recommendations are difficult to use for smallholder farms because of constraints such as access, cost and timeliness in multiple cropping systems. In this study, we combined on-farm experiments from 2012 to 2014 in 20 farmers’ fields on spring maize in Northeast China with a simulation model (Hybrid Maize model), to test the continual performance in agronomic, economic and environmental aspects of the Nutrient Expert for Hybrid Maize decision support system. Six treatments were set as follows: Nutrient Expert (NE), farmers’ practice (FP), soil testing (OPTS) and nitrogen (N), phosphorus (P), and potassium (K) omission treatments based on NE. We estimated yield gaps as the difference between simulated yields with the Hybrid Maize model and measured yields; calculated economic benefit and nutrient use efficiency; and estimated greenhouse gas emissions using published equations approximating nitrous oxide emissions as a function of N fertilizer rate. On average, the NE, FP, and OPTS treatments attained yields of 80%, 74%, and 77% of the potential yield, respectively. The exploitable yield gap between the NE and FP treatments was 0.9tha−1, and between the NE and OPTS treatments was 0.5tha−1. On average, the NE treatment increased the gross return above fertilizer cost (GRF) by US$303 and US$167 compared with the FP and OPTS treatments across all sites, respectively, in which about 91% and 98% of increase GRF was attributed increase in grain yield rather than reduction in fertilizer cost. There were slightly higher nutrient use efficiencies under the NE treatment than under the OPTS treatment. Relative to the FP treatment, however, on average, the NE treatment increased recovery efficiency of N, P, and K by percentage point of 12, 15, and 10, respectively. Agronomic efficiency of N, P, and K were increased by 6, 35, and 10kgkg−1, respectively. Finally, partial factor productivity increased by 14kgkg−1 for N and 45kgkg−1 for P while decreased by 29kgkg−1 for K. Furthermore, the calculated soil inorganic N at harvest of maize crop, total greenhouse gas (GHG, kg CO2 eqha−1) emissions, and GHG emission intensity (kg CO2 eqt−1 grain) were 42%, 17%, and 23% lower in the NE treatment than the FP treatment, respectively. We conclude that the Nutrient Expert for Hybrid Maize system has the potential to close existing yield gaps in the spring maize production systems of Northeast China by improving yield, nutrient use efficiency, and profitability with low environmental pollution.
•We investigated the long term effects of K application on K use and soil status.•K increased grain yield, but this effect decreased with excessive application.•Returned straw, deep soil K ...utilization, weathering soil K pools may alleviate soil K deficits.
The effects of 20 years of potassium (K) fertilization (in two treatments: 113 and 225kg K2Oha−1) on grain and stover yields, plant K concentrations, aboveground K uptake, K use efficiencies, soil K pools, and the K balance were examined in a Haplic Phaeozem soil under a rain-fed mono-cropped spring maize (Zea mays L.) system in the province of Jilin, northeast China. The indigenous K supply (zero K application) maintained an average grain yield of 7.0tha−1 per year, but the year-to-year variation was large. Application of K significantly (P<0.05) increased the average grain yields by 15.1 and 13.8% in the 113 and 225kg K2Oha−1 treatments, respectively, over the experimental period. The mean K recovery efficiency, K agronomic efficiency, and K partial factor productivity decreased from 37.3 to 28.5%, 10.8 to 4.9kgkg−1, and 86.8 to 43.1kgkg−1 when the K application rate increased from 113 to 225kg K2Oha−1. The effect of K application was larger on stover K concentrations than grain K concentrations. In the top 100cm of the soil profile, excessive or non-synchronized K application significantly (P<0.05) increased the leaching of exchangeable K in comparison with the control, but K application had little effect on soil non-exchangeable K and total K. K fertilizer, therefore, plays an important role in increasing grain yields in China, but the K application rate can be reduced if farmers return stover to the soil and make full use of K below the soil surface.
The effects of different tillage management practices on the soil aggregates, soil carbon stock (STCS), and soil nitrogen stock (STNS) are key issues in agricultural research. We conducted an 8-year ...field experiment to evaluate the effects of different tillage methods: stubble cleaning and ridging (CK), no-tillage with stubble retention (NT), plow tillage (PT), and width lines (WL) on soil aggregates, STCS, and STNS in the black soil corn continuous cropping area of Northeast China. Different tillage methods predominantly affected the soil aggregates in the 2-0.25 mm and 0.25-0.053 mm size classes. The PT methods increased the proportion of macroaggregates and improved the quality of the soil aggregates. PT methods significantly increased the soil organic carbon content at the 0-30 cm layer by changing the number of soil macroaggregates. The PT practices are better strategies for enhancing soil carbon sinks, and the WL method increased the total amount of N in the soil pool. Our results suggest that the PT and WL methods are the best strategies for improving the quality of soil aggregates and preventing/reducing depletion of soil C and N in a black soil area of Northeast China.
针对水稻氮肥过量施用和移栽密度过低的问题，研究减氮增密对水稻产量与氮素利用效率的影响，以期为东北寒区水稻生产提供科学依据。于2019—2020年在吉林省前郭县红光农场进行田间试验，共设4个处理，分别为不施氮肥+移栽密度1.80×105穴·hm-2(N0）、传统施氮（氮肥用量235 kg·hm-2）+移栽密度1.80×105穴·hm-2(FP）、较传统施氮减量20%（氮肥用量188 ...kg·hm-2）+移栽密度2.40×105穴·hm-2（SNHD1）、较传统施氮减量20%（氮肥用量188 kg·hm-2）+移栽密度3.00×105穴·hm-2(SNHD2）。对水稻产量、地上部干物质积累与分配、氮素积累与分配以及氮素利用效率进行测定分析。结果表明：SNHD1和SNHD2处理相较于FP处理显著增加了水稻有效穗数，提高了水稻产量，其中SNHD1处理水稻产量增幅达显著水平，两年平均增幅为7.8%。减氮增密提高了水稻各生育时期干物质积累量和氮素积累量，以及水稻齐穗后干物质积累量与氮素积累量占总生育期积累量的比例，且均为SNHD1处理最高。SNHD1和SNHD2处理较FP处理显著提高了氮素吸收率、氮肥农学利用率、氮肥偏生产力和氮肥吸收利用率，且均为SNHD1处理最高，较FP处理两年平均分别提高0.3、6.2、14.4 kg·kg-1和16.4个百分点。氮素表观平衡结果显示，FP、SNHD1和SNHD2处理两年平均表现为盈余，其中SNHD1处理氮盈余量最低。水稻齐穗前、后的干物质积累量和氮素积累量与水稻产量均呈显著正相关，其中水稻齐穗后干物质积累量和氮积累量的相关性高于齐穗前。综上所述，合理的氮肥用量与移栽密度提高了水稻整个生育期干物质积累量和氮素积累量，并提高齐穗后积累比例，进而提高水稻产量和氮素利用效率，综合水稻产量、氮素吸收利用等因素，东北寒地稻区适宜的水稻栽培模式为氮肥用量188 kg·hm-2、移栽密度2.40×105穴·hm-2。 To address the issues related to the excessive use of nitrogen fertilizer and the low transplanting density in rice, the effects of reduced or increased nitrogen density on rice yield and nitrogen
Nonoxidative coupling of methane exhibits promising prospect in that it affords value-added hydrocarbons and hydrogen with high atom economy. However, challenge remains in direct, selective ...conversion of methane to more valuable hydrocarbons like olefins. The current work presents a catalyst with well-dispersed Ta atoms anchored by graphitic C
3
N
4
-supported phthalocyanine. Such a catalyst is able to convert methane selectively to ethylene and propylene at a relatively low temperature (350 °C). The conception of the active center and construction of the catalyst have been described, and the origins of the catalytic performance are discussed.
Objectives
The alteration of bioenergetics by oocytes in response to the demands of various biological processes plays a critical role in maintaining normal cellular physiology. However, little is ...known about the association between energy sensing and energy production with energy‐dependent cellular processes like meiosis.
Materials and methods
We demonstrated that cell cycle‐dependent mitochondrial Ca2+ connects energy sensing to mitochondrial activity in meiosis progression within mouse oocytes. Further, we established a model in mouse oocytes using siRNA knockdowns that target mitochondrial calcium uniporters (MCUs) in order to inhibit mitochondrial Ca2+ concentrations.
Results
Decreased numbers of oocytes successfully progressed to the germinal vesicle stage and extruded the first polar body during in vitro culture after inhibition, while spindle checkpoint‐dependent meiosis was also delayed. Mitochondrial Ca2+ levels changed, and this was followed by altered mitochondrial masses and ATP levels within oocytes during the entirety of meiosis progression. Abnormal mitochondrial Ca2+ concentrations in oocytes then hindered meiotic progress and activated AMP‐activated protein kinase (AMPK) signalling that is associated with gene expression.
Conclusions
These data provide new insight into the protective role that MCU‐dependent mitochondrial Ca2+ signalling plays in meiotic progress, in addition to demonstrating a new mechanism of mitochondrial energy regulation by AMPK signalling that influences meiotic maturation.
When KD‐MCU occurs in oocytes due to impaired mitochondrial function, cytosolic ATP levels decline. The energy sensor AMPK is activated and phosphorylated in response to the increased energetic stress. Excessive activation of AMPK results in adverse effects on the resumption of meiosis. In addition, microtubule dynamics and tension establishment cannot efficiently be achieved, leading to decreased meiotic progression. These observations all implicate MCU as being critical for meiotic progression.
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