▶ No-tillage combined with crop residue mulching was not recommended for spring maize cultivation in the study area. ▶ Ridges covered by plastic film combined with bare furrow may not sustain maize ...productivity in the long run. ▶ Ridges covered by plastic film combined with furrow mulched by crop residue could be a suitable measure for sustaining maize productivity and maintaining soil fertility.
The large dryland area of the Loess Plateau is subject of developing strategies for a sustainable crop production, e.g. by modifications of field management affecting soil water status and crop productivity. A three-year field experiment was conducted to investigate the effects of field management practices on soil water, maize development and yield on the Loess Plateau of China. The field management practices included traditional tillage (CK), no-till with crop residue mulch (SM), alternating ridges mulched with plastic film and bare furrows (PM) and alternating ridges mulched with plastic film and furrows mulched with crop residue (PSM). The soil water storage was higher under SM than the other treatments, except in the first half of the first maize growing season. Higher soil water stimulated maize growth, as indicated by a higher leaf area index and greater biomass accumulation, and thus the highest grain yield (7251
kg
ha
−1) and water use efficiency (2.41
kg
m
−3) in the first experimental season was recorded in SM plots. Maize growth and grain yield did not benefit in the other two seasons. Although soil water storage was similar between PM or PSM and CK treatments at sowing and harvest time, consistently better maize development and higher grain yield were observed through three seasons in PM and PSM plots. Under the PM and PSM treatments grain yield was 8–24% and 13–24% higher, respectively, than under the CK treatment, indicating that utilization of water and other resources was better under these treatments. However, significant soil water depletion in deeper (>100
cm) soil layers was detected at harvest time under PM compared with CK, implying that higher yields might not be sustained in the long run. In conclusion, crop residue mulching combined with no-tillage is not recommended for spring-sown maize system under these temperate climate conditions. Instead, use of ridges mulched with plastic film combined with crop residues in furrows may be an efficient measure to increase crop yield and maintain or improve soil fertility.
The large dryland area of the Loess Plateau (China) is subject of developing strategies for a sustainable crop production, e.g., by modifications of nutrient management affecting soil quality and ...crop productivity. A 19 y long‐term experiment was employed to evaluate the effects of fertilization regimes on soil organic C (SOC) dynamics, soil physical properties, and wheat yield. The SOC content in the top 20 cm soil layer remained unchanged over time under the unfertilized plot (CK), whereas it significantly increased under both inorganic N, P, and K fertilizers (NPK) and combined manure (M) with NPK (MNPK) treatments. After 18 y, the SOC in the MNPK and NPK treatments remained significantly higher than in the control in the top 20 cm and top 10 cm soil layers, respectively. The MNPK‐treated soil retained significant more water than CK at tension ranges from 0 to 0.25 kPa and from 8 to 33 kPa for the 0–5 cm layer. The MNPK‐treated soil also retained markedly more water than the NPK‐treated and CK soils at tensions from 0 to 0.75 kPa and more water than CK from 100 to 300 kPa for the 10–15 cm layer. There were no significant differences of saturated hydraulic conductivity between three treatments both at 0–5 and 10–15 cm depths. In contrast, the unsaturated hydraulic conductivity in the MNPK plot was lower than in the CK plot at depths of 0–5 cm and 10–15 cm. On average, wheat yields were similar under MNPK and NPK treatments and significantly higher than under the CK treatment. Thus, considering soil‐quality conservation and sustainable crop productivity, reasonably combined application of NPK and organic manure is a better nutrient‐management option in this rainfed wheat–fallow cropping system.
Although saline water can be used as an alternative of freshwater resources for agricultural irrigation, especially in arid and semiarid areas, however, unsuitable saline water quality and ...unreasonable irrigation technology may result in the detrimental effects on plant growth, yield and quality of products. Thus, a three-year open field experiment was conducted in Ningxia to investigate the influence of three irrigation water salinity levels (1, 2 and 3 g/L) and five molar concentration ratios (MCR) of Na:Ca (1, 3, 5, 7 and 9) on processing tomato planting, in terms of crop water consumption, tomato yield traits and fruit quality characteristics. The results are as follow: (i) The water consumption decreased significantly with the increasing irrigation water salinity and MCR of Na:Ca. (ii) With the increase of irrigation water MCR of Na:Ca, both the average fruit weight, marketable yield and total yield decreased linearly, as well, the ratio of marketable yield to total yield decreased. Additionally, irrigation water with higher salinity (2 g/L and 3 g/L) and lower MCR of Na:Ca (1 and 3) was more conducive to root water uptake and average fruit weight accumulation, than that with lower salinity and higher MCR of Na:Ca. (iii) With irrigation water salinity of 1 g/L and 2 g/L, both the vitamin C, lycopene, fructose, sucrose and starch content of tomato fruit have quadratic function relationship with the irrigation water MCR of Na:Ca. Moreover, the threshold of irrigation water MCR of Na:Ca for soluble solids, lycopene and starch accumulation was 7, while the content of total soluble sugar, fructose and sucrose achieved the maximum value as the MCR of Na:Ca arrived 5. (iv) With irrigation water salinity of 3 g/L, the total soluble sugar and glucose of fruit decreased with the increase of irrigation water MCR of Na:Ca, especially, the fruit fructose, sucrose and starch concentration decreased linearly, furthermore, the threshold of irrigation water MCR of Na:Ca for vitamin C and soluble solids accumulation was 5. Synthetically, saline water with salt content of 2 g/L and MCR of Na:Ca at 5 was optimal in the present study for mulched drip irrigation on tomato cultivation in the northern Yinchuan plain of Ningxia, obtaining the relatively high-yield (9.72 ×104 kg/hm2) and good-quality of tomato.
•The paper recognized the effects of irrigation water MCR of Na:Ca on tomato yield traits and fruit quality characteristics.•Irrigation water with higher salinity and lower MCR of Na:Ca was more conducive to the increase of average fruit weight.•The study indicated the threshold of irrigation water MCR of Na:Ca for preferable yield and fruit quality characteristics.•The optimal irrigation water salinity and MCR of Na:Ca for high-yield and good-quality of tomato was recommended.
Luminescent metallo-supramolecules have received tremendous attention in recent years owing to their diverse yet well-defined structures, tunable luminescent properties, and broad applications. In ...this context, the development of terpyridine (tpy)-based luminescent metallo-supramolecular systems has seen rapid growth. This review aims to summarize the recent progress of luminescent metallo-supramolecular assemblies from tpy ligands with metal ions, with a focus on discrete metallo-supramolecular architectures and metallo-supramolecular polymers. The design strategies and common approaches for tuning the luminescence properties are detailed along with representative applications. Finally, the pitfalls and unmet challenges regarding the structural characterization and practical applications of tpy-based metallo-supramolecules are discussed followed by our perspectives on the future directions of this field.
This study aimed to explore the experiences of nursing students who have undertaken a short course in an overseas educational system to generate theoretical understanding of the experience of ...studying abroad. Learning in the health professions needs to considered in the context of globalization as a way of sharing knowledge and taking responsibility as world citizens. Studying abroad provides students with an opportunity to develop global health care competencies. A symbolic interactionist approach was adopted to gain insight into how the students constructed the meaning of studying abroad. The study was conducted at a university with 2 campuses in Taiwan. A purposive sampling strategy was employed to recruit 14 participants. Data were collected from August to November 2017 via individual in-depth interviews. A semi-structured interview guide was used. Qualitative content analysis was employed to analyse the data. Each interview was audiotaped and transcribed verbatim. Most students identified both positive and negative experiences related to their professional and personal development and needs. They demonstrated motivation to leave their comfort zone and enter a challenging environment as well as a high level of adaptability. The experience enabled them to see themselves as part of the world and expanded their learning in positive ways. On completion of their course, they encouraged others to experience this enjoyable once-in-a-lifetime opportunity.
In this work, highly dispersed Au nanoparticles (NPs) decorated SiC nanowires (NWs) hybrids were firstly synthesized by a facile deposition-precipitation method. The as-prepared Au/SiC samples were ...characterized using various instrumental methods such as XRD, TEM, EDS, UV–vis DRS, BET, FTIR, XPS, PL, TRPL, and photoelectronchemical measurements. The solar H2 production performances were investigated by using Na2S as sacrificial reagents in water under simulated sunlight illumination produced from a 300 W xenon lamp. Results showed that a significantly enhanced photoactivity for H2 evolution (1495.8 μmol h−1·g−1) with apparent quantum efficiency (AQE) of 2.12% was achieved over the compostion-optimized Au/SiC composite (with 0.5 wt% Au), which was much higher than those of pure SiC NWs, Pt NPs deposited SiC NWs sample as well as the previously reported SiC-based catalysts. In cyclic tests, the AS0.5 showed acceptable photocatalytic stability and good structural stability. PL, TRPL and photoelectrochemical measurements disclosed that improved charge separation and retarded charge recombination were realized. However, the Au-loaded SiC products with strong surface plasmon resonance (SPR) absorption showed no activity for visible light photocatalytic H2 production (λ ≥ 400 nm). Based on band-gap structures, the critical factors for SPR effect of Au NPs in activating or enhancing the visible-light photoactivities of semiconductors were proposed. This work can pave the avenue to the development of plasmonic metal decorated other narrow band gap semiconductors with plasmon-enhanced visible-light photoactivity for solar water splitting and related applications.
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•A deposition-precipitation method was used to prepare Au/SiC nanohybrids.•The enhanced charge transfer and separation efficiency of Au/SiC was achieved.•Au/SiC hybrids showed improved photocatalytic and photoelectrochemical activity.•Mechanisms of improved performances over Au/SiC were proposed and discussed.•Au played an electron tank role in boosting the activity of SiC rather than SPR role.
Although unconventional water can be applied as an alternative for agricultural production, inappropriate irrigation water quality may adversely affect the soil crop system. Thus, field experiments ...under mulched drip irrigation were performed over three years (2017–2019) to investigate the impacts of three salinity (1, 2 and 3 g·L−1) with five Na:Ca molar ratios (1, 3, 5, 7 and 9) of irrigation water on tomato plant growth, fruit development, soil salt accumulation and soil sodium adsorption ratio. The results showed that, with irrigation water salinity of 1 g·L−1, the critical value of irrigation water Na:Ca molar ratio for the high yield and dry matter accumulation was 3 and 5, respectively, while the threshold for high concentration of vitamin C and lycopene was 7. With the irrigation water salinity of 2 g·L−1 and 3 g·L−1, the Na:Ca molar ratio threshold for a high concentration of soluble solids, vitamin C and lycopene was 5. Moreover, considering the increase of plant nitrogen and phosphorus accumulation, the decrease of sodium adsorption ratio at 40–100 cm soil layer inside the film, and the diminution of soil salt accumulation at 0–100 cm layer, irrigation water with higher salinity and lower Na:Ca molar ratio was more proper than that with lower salinity and higher Na:Ca molar ratio. Based on the multi-objective optimization with entropy-weight TOPSIS method, irrigation water with a salinity level at 2 g·L−1 and the Na:Ca molar ratio at 5 was suggested for tomato planting in the Yinbei Yellow River Irrigation District, China.
•The effects of irrigation water Na:Ca molar ratio on soil-crop system was indicated.•Critical values of Na:Ca molar ratio for high-yield and good-quality were recognized.•Appropriate water salinity and Na:Ca molar ratio for tomato cultivation in Ningxia.
Hydrogen sulfide (H2S) plays an important role as a signaling compound (gasotransmitter) in living systems. However, the development of an efficient imaging chemosensor of H2S in live animals is a ...challenging field for chemists. Herein, a novel peptide-based fluorescence chemosensor L-Cu was designed and synthesized on the basis of the copper chelating with the peptide ligand (FITC–Ahx–Ser–Pro–Gly–His–NH2, L), and its H2S sensing ability has been evaluated both in living cells and zebrafish. The peptide backbone and Cu2+-removal sensing mechanism are used to deliver rapid response time, high sensitivity, and good biocompatibility. After a fast fluorescence quench by Cu2+ coordinated with L, the fluorescence of L is recovered by adding S2− to form insoluble copper sulfide in aqueous solution with a detection limit for hydrogen sulfide measured to be 31nM. Furthermore, the fluorescence chemosensor L-Cu showed excellent cell permeation and low biotoxicity to realize the intracellular biosensing, L-Cu has also been applied to image hydrogen sulfide in live zebrafish larvae. We expect that this peptide-based fluorescence chemosensor L-Cu can be used to study H2S-related chemical biology in physiological and pathological events.
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•Welan gum production using cane molasses by Alcaligenes sp. ATCC31555 was explored.•The process was optimized by molasses pretreatment, agitation control and addition of additives.•Welan gum ...production and yield obtained in the optimal process were highest so far.•Welan gum from molasses displayed similar physical properties to that from glucose.•Cane molasses may be a suitable substrate for welan gum production on industrial scale.
Welan gum production by Alcaligenes sp. ATCC31555 from cane molasses was studied in batch fermentation to reduce production costs and enhance gum production. The pretreatment of cane molasses, agitation speed and the addition of supplements were investigated to optimize the process. Sulfuric acid hydrolysis was found to be the optimal pretreatment, resulting in a maximum gum concentration of 33.5g/L, which is 50.0% higher than those obtained from the molasses’ mother liquor. Agitation at 600rpm at 30°C and addition of 10% n-dodecane following fermentation for 36h increased the maximum gum production up to 41.0±1.41g/L, which is 49.1% higher than the greatest welan gum concentration in the literature so far. The welan gum product showed an acceptable molecular weight, similar rheological properties and better thermal stability to that obtained from glucose. These results indicate that cane molasses may be a suitable and inexpensive substrate for cost-effective industrial-scale welan gum production.
Rice production involves abundant water and fertilizer inputs and is prone to nitrogen (N) loss via surface runoff and leaching, resulting in agricultural diffuse pollution. Based on a two-season ...paddy field experiment in Jiangsu Province, China, field water and N dynamics and their balances were determined with the well-calibrated HYDRUS-1D model. Then, scenarios of different controlled drainage and N fertilizer applications were simulated using the HYDRUS-1D model to analyze the features and factors of N loss from paddy fields. Evapotranspiration and deep percolation were the two dominant losses of total water input over the two seasons, with an average loss of 50.9% and 38.8%, respectively. Additionally, gaseous loss of N from the whole soil column accounted for more than half of total N input on average, i.e., ammonia volatilization (17.5% on average for two seasons) and denitrification (39.7%), while the N uptake by rice accounted for 37.1% on average. The ratio of N loss via surface runoff to total N input exceeded 20% when the N fertilizer rate reached 300 kg ha−1. More and longer rainwater storage in rice fields under controlled drainage reduced surface runoff losses but increased the risk of groundwater contamination by N leaching. Therefore, compared with raising the maximum ponding rainwater depth for controlled drainage, optimizing N fertilizer inputs may be more beneficial for controlling agricultural diffuse pollution by reducing N loss via surface runoff and leaching. The HYDRUS-1D model provides an approach for the quantitative decision-making process of sustainable agricultural water and N management.
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