Development Of High Efficiency Research Articles

Broadband near-infrared emission in Cr3+-doped MgO-Al2O3-SiO2 dual-phase glass-ceramics for near-infrared spectroscopy applications

Broad-band and high-efficiency NIR-emitting materials are widely used in near-infrared (NIR) spectroscopy technology. Here, a series of Cr3+-doped dual-phase glass-ceramics were successfully prepared. The Mg2Al4Si5O18 and MgAl2Si3O10 nanocrystals with particle sizes smaller than 200 nm were precipitated simultaneously in glass-ceramics. The density and molar volume showed an opposite trend with the rise in crystallization temperatures. The two excitation bands were revealed in the excitation spectra monitored at 985 nm, and the crystal field strength of Cr3+ was 2.259 ∼ 2.542. Under the excitation of 400 nm and 466 nm xenon lamps, the broadband emission peaks centered at ∼985 nm with a full width at half maximum of 148∼169 nm were observed, indicating that the dual-phase glass-ceramics were suitable for NIR spectroscopy. Furthermore, the tunable emission was achieved by selective enrichment of Cr3+ ions into Mg2Al4Si5O18 and MgAl2Si3O10 nanocrystals, which paves the way for the development of high-efficiency and broadband NIR emitting materials.

Electronic modulation of iridium-molybdenum oxides with a low crystallinity for high-efficiency acidic oxygen evolution reaction

The development of high-efficiency and stable acidic oxygen evolution reaction (OER) is of great importance toward overall water splitting but challenging. Here, we report the electronic modulation of iridium oxides through the introduction of molybdenum to boost the OER performance in an acidic electrolyte. Remarkably, the prepared iridium-molybdenum oxide (IrMoOx) nanofibers with a low crystallinity through an electrospinning-calcination strategy show a superior OER activity in an acidic electrolyte with a low overpotential of 267 mV at 10 mA cm−2 compared with bare IrOx (333 mV) and MoOx (almost no OER activity) as well as the benchmark commercial IrO2 catalyst (330 mV). Furthermore, the IrMoOx nanofibers catalyst exhibits an excellent long-term stability with a slight degradation of the current density after 30 h because of the strong electronic interactions between IrOx and MoOx components. Furthermore, an overall water splitting device assembled with IrMoOx and Pt/C as electrodes delivers a cell voltage of 1.54 V at 10 mA cm−2 and desirable long-term stability, much better than Pt/C||IrO2 electrolyzer (1.66 V). This work offers a simple and efficient route to fabricate metal oxide-based electrocatalysts with bimetallic active sites, presenting a synergistic enhanced OER performance at a low pH circumstance.

A nanoflower-like polypyrrole-based cobalt-nickel sulfide hybrid heterostructures with electrons migration to boost overall water splitting

The development of high-efficiency and cost-effective difunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are highly attractive to fulfill the practical water electrolysis. Herein, a novel low-cost difunctional cobalt-nickel sulfide (Co3S4/Ni3S2) flower-like heterostructures are purposely loaded on the surface of polypyrrole (PPy) nanosheets on nickel foam (NF) via feasible and efficient electrodeposition and hydrothermal tactics. The unique hierarchical architecture of the PPy nanosheets and strong electron interaction in the Co3S4/Ni3S2 nanohybrid effectively offer sufficient specific surface area and regulate electronic configuration for expediting the electrocatalytic process. The theoretical simulations also provide convincing proof that the interface of the Co3S4/Ni3S2 heterostructures supplies a lower energy pathway for water adsorption and dissociation, and the electrons migration that occurs when heterostructures emerge is probably the root of the result above. Consequently, the as-fabricated Co3S4/Ni3S2@PPy/NF exhibits outstanding electrochemical activity of HER and OER requiring low overpotentials of 63 mV and 207 mV to reach a current density of 10 mA cm−2 in the alkaline electrolyte, respectively. When equipped in a two-electrode electrolyzer, the Co3S4/Ni3S2@PPy/NF electrode couple displays a low voltage of only 1.52 V at 10 mA cm−2, indicating its potential application in the field of the water electrolysis.

Effects of enzymatic hydrolysis and alkalization pretreatment on biohydrogen production by chlorella photosynthesis

The effects of alkalization pretreatment and enzymolysis on biohydrogen production with Chlorella vulgaris microalgae biomass by photosynthesis were studied, the alkalization pretreatment enzymolysis was to alkalize biomass raw materials before enzymolysis, the biohydrogen production kinetics equation of microalgae biomass was put forward by comparing the biohydrogen process of enzymatic hydrolysis with that of alkaline pretreatment enzymatic hydrolysis. The experimental results show: the optimum initial substrate concentration for biohydrogen production by enzymatic hydrolysis and alkaline pretreatment was 24 g/L, the maximum biohydrogen was 132.1 mL and 294.5 mL, the maximum specific biohydrogen production was 22.0 mL/g and 49.1 mL/g, and the maximum biohydrogen content was 43.9% and 56.8%. The effect of biohydrogen production by enzymatic hydrolysis after alkaline pretreatment of microalgae biomass is obviously better than that by direct enzymatic hydrolysis, which provides scientific reference and development of high efficiency and low cost biohydrogen production technology by photosynthesis of microalgae biomass.

Hydrophobic modification of castor oil-based polyurethane coated fertilizer to improve the controlled release of nutrient with polysiloxane and halloysite

Castor oil has been developed rapidly as a bio-based coating material for controlled-release fertilizers. However, the release characteristics of coated fertilizers are limited because the coating materials are hydrophilic with many micropores. To improve the surface hydrophobicity of coating materials, superhydrophobic halloysite nanotubes (SHTs) were fabricated by hydrolytic condensation of siloxane on the surface of halloysite nanotubes (HNTs). SHTs were used to modify the castor oil-based polyurethane (SHPU) to enhance the surface nanoscale roughness and reduce surface energy. Compared with a PU-coated fertilizer (PUC), the nitrogen-release properties of the hydrophobic PU-coated fertilizer (SHPUC) were improved significantly. This improvement was because the nanoscale surface roughness and hydrophobicity of SHPU increased the water contact angle, and the micropores on the surface were blocked by nanotubes and hindered water entrance into the coating. This method of hydrophobic modified coating materials could provide a new idea for development of high efficiency and environmentally friendly bio-based coated controlled-release fertilizer and sustainable development of agriculture.

Superdurable Bifunctional Oxygen Electrocatalyst for High-Performance Zinc-Air Batteries.

The development of high-efficiency and durable bifunctional electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical for the widespread application of rechargeable zinc-air (Zn-air) batteries. This calls for rational screening of targeted ORR/OER components and precise control of their atomic and electronic structures to produce synergistic effects. Here, we report a Mn-doped RuO2 (Mn-RuO2) bimetallic oxide with atomic-scale dispersion of Mn atoms into the RuO2 lattice, which exhibits remarkable activity and super durability for both the ORR and OER, with a very low potential difference (ΔE) of 0.64 V between the half-wave potential of ORR (E1/2) and the OER potential at 10 mA cm-2 (Ej10) and a negligible decay of E1/2 and Ej10 after 250 000 and 30 000 CV cycles for ORR and OER, respectively. Moreover, Zn-air batteries using the Mn-RuO2 catalysts exhibit a high power density of 181 mW cm-2, low charge/discharge voltage gaps of 0.69/0.96/1.38 V, and ultralong lifespans of 15 000/2800/1800 cycles (corresponding to 2500/467/300 h operation time) at a current density of 10/50/100 mA cm-2, respectively. Theoretical calculations reveal that the excellent performances of Mn-RuO2 is mainly due to the precise optimization of valence state and d-band center for appropriate adsorption energy of the oxygenated intermediates.

Influence of Teacher Behaviors on Student Activities in Information-Based Classroom Teaching

Under the background of teaching requirements comprehensively satisfied by information hardware, clarifying the influencing factors of teaching behaviors on student activities in the information-based teaching, as well as the influence mechanism. In this paper, a mediator model was established. Next, the collaboration degree in the teaching process was taken as the influencing factor and information monitoring was used as the mediating variable to discuss the effect of teaching behaviors on student activities in the classroom teaching process. Subsequently, the structural equation model (SEM) was used to mine the relationship between teaching behaviors and student activities and the influence on student activities. It was discovered that the overall Cronbach’s a value of questionnaires was 0.920, indicating a favorable questionnaire reliability; the KMO value was 0.916, which represents excellent questionnaire validity; three factors—teachers’ teaching behaviors, collaboration degree, and media monitoring—have shown positively strong correlations with student activities. The research results have provided realistic examination for enriching information-based classroom factors like teaching concepts, teaching resources and teaching quality, mine the existing problems and further provide reform orientation for promoting the high-efficiency development of information-based teaching, completing the effective engagement between information technology and specialized courses, and integrating abundant information-based teaching resources.

Potential Antiviral Action of Alkaloids.

Viral infections and outbreaks have become a major concern and are one of the main causes of morbidity and mortality worldwide. The development of successful antiviral therapeutics and vaccines remains a daunting challenge. The discovery of novel antiviral agents is a public health emergency, and extraordinary efforts are underway globally to identify safe and effective treatments for different viral diseases. Alkaloids are natural phytochemicals known for their biological activities, many of which have been intensively studied for their broad-spectrum of antiviral activities against different DNA and RNA viruses. The purpose of this review was to summarize the evidence supporting the efficacy of the antiviral activity of plant alkaloids at half-maximum effective concentration (EC50) or half-maximum inhibitory concentration (IC50) below 10 μM and describe the molecular sites most often targeted by natural alkaloids acting against different virus families. This review highlights that considering the devastating effects of virus pandemics on humans, plants, and animals, the development of high efficiency and low-toxicity antiviral drugs targeting these viruses need to be developed. Furthermore, it summarizes the current research status of alkaloids as the source of antiviral drug development, their structural characteristics, and antiviral targets. Overall, the influence of alkaloids at the molecular level suggests a high degree of specificity which means they could serve as potent and safe antiviral agents waiting for evaluation and exploitation.

Research progress of natural products for the treatment of ischemic stroke.

Stroke is a leading cause of death and disability world-widely. The incidence rate of stroke has been increasing due to the aging population and lifestyle changes. At present, the only drug approved by the US Food and Drug Administration (FDA) for the treatment of ischemic stroke is tissue plasminogen activator (t-PA), but its clinical application is greatly limited because of its narrow time window and bleeding risk. Natural products have a long history of being used in traditional medicine with good safety, making them an important resource for the development of new drugs. Indeed, some natural products can target a variety of pathophysiological processes related to stroke, including oxidative stress, inflammation and neuronal apoptosis. Therefore, the development of high-efficiency, low-toxicity, safe and cheap active substances from natural products is of great significance for improving the treatment alternatives of patients with stroke. This article reviews the neuroprotective effects of 33 natural compounds by searching recent related literature. Among them, puerarin, pinocembrin, quercetin, epigallocatechin-3-gallate (EGCG), and resveratrol have great potential in the clinical treatment of ischemic stroke. This review will provide a powerful reference for screening natural compounds with potential clinical application value in ischemic stroke or synthesizing new neuroprotective agents with natural compounds as lead compounds.

Enhanced electrocatalytic performance of N-doped carbon xerogels obtained through dual nitrogen doping for the oxygen reduction reaction.

The development of high efficiency and low-cost electrocatalysts for the oxygen reduction reaction (ORR) is urgently desired for many energy storage and conversion systems. Nitrogen-doped carbon xerogels (NCXs) which have been successfully applied as effective electrocatalysts for the ORR have continued to attract attention due to their competitive price and tunable surface chemistry. A new dual N-doped NCX (NCoNC) electrocatalyst is fabricated as a carbon based catalyst though a facile impregnation of peptone in a precursor and ammonia etching pyrolysis method. XPS analysis demonstrates that the NCoNC electrocatalyst not only has a high N doping amount, but also has an optimized chemical state composition of N doping, which play an important role in improving the microstructure and catalytic performance of the catalysts. XRD and HRTEM results show that the doped metal nano-particles are coated with a double carbon layer of graphene carbon (inner layer) and amorphous carbon (outer layer) forming serrated edges that facilitate the ORR process. The as-obtained NCoNC catalyst exhibits good electrocatalytic performance and excellent stability for the ORR in both acidic and alkaline environments. In particular, in alkaline electrolyte, the decrements of both the limiting current density and the half-wave potential of the NCoNC catalyst were significantly lower than those of a commercial Pt/C catalyst during accelerated aging tests. When serving as an air electrode in Zn–air batteries, the catalyst also exhibits superior catalytic performance with a peak power density of 78.2 mW cm−2 and a stable open-circuit voltage of 1.37–1.43 V. This work presents a novel tactic to regulate the microstructure and composition of carbon-based electrocatalysts by the facile and scalable dual-effect nitrogen doping method which may be conducive to promoting and developing highly efficient and promising electrocatalysts for the ORR.

Fabrication of bimetallic metal-organic frameworks derived Fe3O4/C decorated graphene composites as high-efficiency and broadband microwave absorbers

Developing strong absorption and broadband microwave absorbers derived from metal-organic frameworks (MOFs) still remains a big challenge in the field of microwave absorption. Herein, iron zinc bimetallic metal-organic frameworks/reduced graphene oxide (FeZn-MOFs/RGO) precursors derived ferroferric oxide/carbon (Fe 3 O 4 /C) decorated graphene composites were fabricated via a solvothermal and carbonization two-step strategy. It was found that the morphology of carbon frameworks could be regulated from the traditional regular octahedron to the pomegranate shape by simply adjusting the molar ratios of Fe 3+ to Zn 2+ in the precursors. Moreover, results revealed that the molar ratios of Fe 3+ to Zn 2+ had notable effects on the electromagnetic parameters and microwave attenuation capacity of attained composites. Significantly, the obtained composites with the molar ratio of Fe 3+ to Zn 2+ of 1:2 presented the optimal electromagnetic attenuation performance, i.e. the minimum reflection loss achieved −79.0 dB with a matching thickness of 2.76 mm and effective absorption bandwidth was as high as 5.8 GHz under a thin thickness of 1.8 mm and low filling ratio of 20.0 wt%. Additionally, the potential microwave dissipation mechanisms were illuminated. Therefore, our results would shed light on the development of high-efficiency and broadband microwave absorbing composites derived MOFs. • Fe 3 O 4 /C decorated graphene composites derived from bimetallic MOFs were prepared. • Morphology of carbon frameworks evolved from octahedron to pomegranate shape. • Microwave absorption was regulated by adjusting the molar ratios of Fe 3+ to Zn 2+ . • Strong absorption, broad bandwidth, thin thickness and low loading were achieved. • The potential microwave dissipation mechanism of attained composites was proposed.

Development of 1MHz Class High Frequency Optical Microphone and Its Application to Jet Noise Reduction Device Performance Investigation

In the development of jet noise reduction devices, high efficiency and low cost can be achieved by using 1% scale nozzles and low-density gas as an alternative to full scale devices and hot gas. However, very high frequency noise is generated from the nozzle, and the upper limit frequency of a normal condenser microphone is insufficient. Therefore, a high frequency optical microphone based on the Schlieren method was developed, which measures the density gradient caused by the sound wave. The frequency response of the optical microphone was numerically calculated and corrected, and the frequency response was investigated using the characteristics of jet noise. Additionally, the noise reduction performance of the ejector nozzle was investigated using the optical microphone.

Bimetal phosphide as high efficiency and stable bifunctional electrocatalysts for hydrogen and oxygen evolution reaction in alkaline solution.

The development of low-cost, high-efficiency, and stable bifunctional electrocatalysts for large-scale water electrolysis is very important for the sustainable development of energy. In this paper, the nickel cobalt phosphide (CoNiP) microstructure was prepared by the “in situ growth-ion exchange-phosphating” method. Due to the flake structure and the synergistic effect of the bimetal, the synthesized CoNiP microstructure exhibited high electrocatalytic activity and stability for hydrogen and oxygen evolution in alkaline electrolyte. The optimized CoNiP showed low overpotential of 116 mV at 10 mA cm−2 for hydrogen evolution reaction and 400 mV at 50 mA cm−2 for oxygen evolution reaction in KOH solution. In addition, it exhibited long-term stability at a high constant current density of 100 mA cm−2 for 48 hours at room temperature and for 65 hours at 80 °C without significant degradation. Theoretical results showed that the introduction of Co and P atoms could reduce the reaction barrier and improve the electron transfer ability. This work provides a simple and economical way for the synthesis of electrocatalytic bimetal phosphide catalysts.

Synthesis, characterization, and anti-hepatocellular carcinoma effect of glycyrrhizin-coupled bovine serum albumin-loaded luteolin nanoparticles

Background: Luteolin (Lut) is a natural flavonoid with low water solubility. Many studies have revealed that its antitumor effect is more understandable. Objectives: Synthesis of glycyrrhizin-coupled bovine serum albumin-loaded Lut nanoparticles (GL-BSA-Lut-Nps) to progress the water solubility, anticancer effect, liver targeting, cycle arrest, induction apoptosis, and regulating the metabolism of Lut. Materials and Methods: The activity screening of GL-BSA-Lut-Nps on Hepatocellular Carcinoma Bel-7402 cells was spotted by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, cell cycle, and apoptosis were measured by flow cytometry. The solubility of GL-BSA-Lut-Nps was evaluated by ultraviolet spectrophotometer. Fluorescein isothiocyanate was employed to label the drug, and the fluorescence intensity of cells after drug uptake was detected under a fluorescence microscope to sense the targeting of GL-BSA-Lut-Nps to tumor cells. The differences of metabolites between Bel-7402 cells treated with GL-BSA-Lut-Nps and the control group were considered by 1 hydrogen-nuclear magnetic resonance metabolomics. Results: The results presented that the GL-BSA-Lut-Nps prepared by solvent removal method had good anti-tumor activity and water solubility in vitro and the No. 4 Lut nanoparticles (GL-BSA-Lut-Nps-4) screened by the MTT method had the best effect. The IC50 of the GL-BSA-Lut-Nps-4 on the Bel-7402 cell inhibition test was 1.999 ± 0.880 mg/mL. The results of cell cycle and apoptosis displayed that the anticancer effect of the prescription is more palpable. The results of the fluorescence original method are proposed to confirm that the experimentally created GL-BSA-Lut-Nps-4 have a liver targeting effect. The study of metabolomics further clarified the metabolic regulation effect of GL-BSA-Lut-Nps-4 on Bel-7402 cells. Conclusion: It delivers a theoretical basis for the development of new high-efficiency and low-toxicity traditional Chinese medicine preparations for liver cancer.

Atomistic Engineering of Ag/Pt nanoclusters for remarkably boosted mass electrocatalytic activity

It is of vital importance to boost the intrinsic activity and augment the active sites of expensive and scarce platinum-based catalysts for advancing a variety of electrochemical energy applications. We herein report a mild electrochemical bottom-up approach to deposit ultrafine, but stable, Pt8Ag4 alloy clusters on carbon nanotubes (CNTs) by elaborately designing bimetallic organic cluster precursors with four silver and eight platinum atoms coordinated with µ,σ-bridged ethynylpyridine ligands, i.e., [Ag4(C24H16N4Pt)8(BF4)4]. The Pt8Ag4 cluster/CNT hybrids present impressively high platinum mass activity that is threefold that of commercial Pt/C toward the hydrogen evolution reaction, as a result of the cooperative contributions from the Ag atoms that enhance the intrinsic activity and the CNT supports that increase the activity sites. The present work affords an attractive avenue for engineering and stabilizing Pt-based nanoclusters at the atomic level and represents a promising strategy for the development of high-efficiency and durable electrocatalysts.

Several potentiality enhancement techniques of water flooding reservoir in placanticline

The three types of oil reservoirs in water drive have entered the later stage of ultra-high water cut development [1] after three times of well pattern infilling adjustment and years of oil stabilization and water control. With the gradual transfer of high quality reserves to chemical flooding, the development objects of water flooding are mainly three types of oil reservoirs, and the exploitation objects are getting worse and worse, and the difficulty of controlling decline, exploiting potential and benefit development is increasing year by year. To this end, the blocks that have been tested for water control and efficiency improvement are selected to conduct precise potential-tapping tests, to carry out technological breakthroughs of “water control and efficiency improvement”, to explore and form a series of high-efficiency development technologies of water flooding, and to guide the deep potential-tapping in the ultra-high water-cut stage of water flooding [2]. This paper mainly focuses on the comprehensive utilization of injection and production well pattern, as well as the principle and effect of injection well comprehensive adjustment program and tracking adjustment program.

Quantitatively study on imbibition of fracturing fluid in tight sandstone reservoir under high temperature and high pressure based on NMR technology

Reservoir fracturing is one of the main technical means to realize high-efficiency development of low-permeability tight reservoirs in oil fields. With the implementation of reservoir fracturing measures, the imbibition effect is produced after the interaction between fracturing fluid and rocks in oil reservoirs. It is of great guiding significance to study the imbibition mechanism of fracturing fluid and quantitatively evaluate the imbibition effect of fracturing fluid with different pore throats under different conditions for practical development. In this paper, to reveal the mechanism of fracturing fluid imbibition from a microscopic point of view, based on the simulation of high temperature and high-pressure reservoir environment, using nuclear magnetic resonance (NMR) technology and dynamic physical simulation experiments, we quantitatively evaluated the imbibition effect of fracturing fluid with different pore throats at different times and investigated the influence of permeability, wettability, and viscosity of fracturing fluid on imbibition effect of fracturing fluid. The results show that the scale of imbibition of fracturing fluid is between 0.10 ms–51.20 ms. Additionally, the imbibition rate is the fastest in the initial stage of imbibition. Furthermore, the imbibition takes place in micropores (0.10 ms–1.00 ms) first, and then enters mesopores (1.00 ms–10.00 ms), followed by macropores (>10.00 ms) as the reaction time goes on. Also, micropores (0.10 ms–1.00 ms) are the best contributors to the imbibition effect of fracturing fluid, and the imbibition effect tends to be stable at first, followed by mesopores (1.00 ms–10 ms), with the highest contribution, but its imbibition effect is relatively lagging. Last, the imbibition efficiency is positively correlated with permeability, negatively correlated with fracturing fluid viscosity. It is also related to wettability. The imbibition effect of hydrophilic type is better than that of oleophilic type. The more hydrophilic the rock is, the better the imbibition effect is, and the imbibition stability time of the hydrophilic type lags behind that of the oleophilic type.

Flower-like CuCoMoOx nanosheets decorated with CoCu nanoparticles as bifunctional electrocatalysts for hydrogen evolution reaction and water splitting

The development of high efficiency, low-budget and excellent stability of electrocatalysts is a critical factor to improve water decomposition. Herein, a highly active 3D bulk catalysts of core-shell nanostructures, in which Flower-like CuCoMoOx nanosheets embellished with CoCu alloy nanoparticles are evenly wrapped on Cu NWs cores supported on CF, toward overall water splitting is firstly reported. The coaction of CoCu alloy nanoparticles and CuCoMoOx nanosheets with 3D hierarchical and porous nanoarchitecture can accelerate the ionization of H2O molecules and formation of H2. Meanwhile, the connection nanosheets of Cu NWs with noteworthy conductivity, resulting in rapid electron transport, exhibits outstanding both HER and OER activities and remarkable overall water splitting characteristics in the alkaline medium. As an electrocatalyst for HER and OER, the low overpotential of 75 mV and 315 mV at 100 mA cm−2, and low voltage of 1.66 V for overall water splitting are achieved, even superior to the benchmark of IrO2/CF (+) // /Pt/C/CF(-) in 1 M KOH. This work has a significant reference to hydrogen production for the electrolytic water industry.

Effects of water limiting and nitrogen reduction on nitrogen use and apparent balance of winter wheat in the Guanzhong Plain, Northwest China

Effects of water limiting and nitrogen reduction on yield, nitrogen use efficiency and nitrogen apparent balance of wheat were investigated to explore whether it would be feasible to restrict water and reduce nitrogen in wheat production of the Guanzhong Plain and thus to provide scientific supports for yield-stable, high-efficiency, and environment-friendly developments in the irrigated production of winter wheat. Following a split-plot design with two water regimes as the main plots and four N addition rates as sub-plot factors, a field experiment (2017-2019) was conducted in Yangling, Shaanxi. The two water regimes were conventionally irrigating at the rate of 60 mm during the overwinter period and at the jointing stage, respectively (W2, a conventional practice) and irrigating at a rate of 60 mm during the overwintering period (W1, a restrictive irrigation practice). The four nitrogen addition rates were 300 kg·hm-2(N300, a conventional N rate), 225 kg·hm-2 (N225, a nitrogen rate of 25% less than the convention), 150 kg·hm-2(N150, a nitrogen rate 50% of less than the convention), and 0 kg·hm-2(N0, no nitrogen applied). The decreased irrigation rate and nitrogen rate significantly increased nitrogen content in the plants and grains, yield, N output, nitrogen use efficiency, nitrogen harvest index, nitrogen recovery efficiency, and nitrogen agronomic efficiency, reduced nitrate leaching and N surpluses, and maintained nitrogen balance. With both W1 and N150 adopted, the increased irrigation rate and nitrogen rate did not affect yield and N output of winter wheat in 2017-2019. Plant nitrogen content with both W1 and N150 adopted increased by 0.1%-25.5% and 14.0%-31.6% and the grain nitrogen content increased by 0.1% and 4.6%, compared with those with both W2 and N300 adopted in 2017-2018 and 2018-2019, respectively. Nitrogen use efficiency, nitrogen harvest index, nitrogen recovery efficiency, and nitrogen agronomic efficiency were averagely increased by 95.3%, 4.2%, 81.7% and 33.0% respectively. The N surplus was decreased by 97.2% and 95.1%, which effectively alleviated soil nitrate leaching. Considering all the indicators, irrigating at 600 m3·hm-2 during the overwintering period plus applying nitrogen at 150 kg·hm-2 could achieve high yield, high efficiency, and environment friendly development of winter wheat in the Guanzhong Plain of Shaanxi.

Comprehensive device simulation of 16.9% efficient two-terminal PbS–PbS CQD tandem solar cell

The significant losses that limit the efficiency of a single-junction solar cell are thermalization loss and transmission loss. Thus, to efficiently utilize the solar spectrum and mitigate these losses, tandem solar cells (TSCs) have significantly impacted the photovoltaic (PV) landscape. In this context, the research on perovskite/silicon tandems is currently dominating the research community. However, challenges such as stability of perovskite, pin-hole defects, conformal deposition of perovskite over textured silicon, the low absorption coefficient of silicon, and high module cost of the bottom subcell are the tailback for its mass production at the industrial level. Therefore, considering the detailed balance limit for the TSC, a low-cost solution-processed top and bottom subcells with a tunable bandgap can be well thought for the low-cost tandem design. Thus, here in this work, two different PbS–PbS colloidal quantum dot (CQD) TSCs with a conversion efficiency of 15.6% and 16.9% are proposed through comprehensive device simulations. Three different PbS-CQDs with a bandgap of 1.14eV, 1.45eV, and 1.56eV are utilized to design the TSCs under consideration. Detailed standalone and tandem analysis has been carried out in terms of absorber layer thickness variation, filtered spectrum, filtered integrated power, current matching, tandem current density voltage (J-V) curves, and tandem PV parameter to finalize the conversion efficiency. The filtered spectrums are obtained by using the transfer matrix method to account for the interfacial reflection losses and thin-film interference effects. The tandem device constructed using 1.45eV and 1.56eV based top subcell showed the open-circuit voltage V OC of as high as 1.71V and 1.83V, respectively. The comprehensive theoretical analysis of PbS–PbS CQD tandem devices proposed in this work may pave the way for developing high-efficiency TSCs for low-cost applications. • Two different PbS–PbS CQDs tandem solar cells (TSCs) with a conversion efficiency of 15.60% and 16.92% are proposed. • Detailed standalone and tandem analysis has been carried out to optimize the conversion efficiency. • Three different PbS-CQDs with a bandgap of 1.14eV, 1.45eV, and 1.56eV are utilized to design the TSCs under consideration. • TSCs constructed using 1.45eV and 1.56eV based top subcell showed the open-circuit voltage V OC of 1.71V and 1.83V, respectively. • This detailed study would open path for development of high-efficiency, low-cost perovskite-PbS CQD TSCs in future.