The search for Pt‐free electrocatalysts exceeding pH‐universal hydrogen evolution reaction (HER) activities when compared to the state‐of‐the‐art commercial Pt/C is highly desirable for the ...development of renewable energy conversion systems but still remains a huge challenge. Here a colloidal synthesis of monodisperse Rh2P nanoparticles with an average size of 2.8 nm and their superior catalytic activities for pH‐universal HER are reported. Significantly, the Rh2P catalyst displays remarkable HER performance with overpotentials of 14, 30, and 38 mV to achieve 10 mA cm−2 in 0.5 m H2SO4, 1.0 m KOH, and 1.0 m phosphate‐buffered saline, respectively, exceeding almost all the documented electrocatalysts, including the commercial 20 wt% Pt/C. Density functional theory calculations reveal that the introduction of P into Rh can weaken the H adsorption strength of Rh2P to nearly zero, beneficial for boosting HER performance.
2.8 nm monodisperse Rh2P nanoparticles with narrow size distribution are synthesized through a one‐pot hot solution colloidal synthetic route and further used as remarkable catalysts for pH‐universal hydrogen evolution reaction (HER). The enhanced HER performance is attributed to the introduction of P into Rh, which resulting in the optimized free energy of hydrogen adsorption.
Developing highly efficient electrocatalysts and fundamentally understanding the mechanisms for alkaline hydrogen electrode reactions, including the hydrogen oxidation reaction (HOR) and the hydrogen ...evolution reaction (HER), are highly desirable. Here we report the synthesis of the IrMo alloy nanocatalyst and its outstanding HOR/HER performances under alkaline media. Specifically, the IrMo0.59 exhibits the highest catalytic activities, which are 5 times higher than that of Ir and commercial Pt/C toward HOR and even a 10-fold enhancement toward HER. Density functional theory (DFT) calculations reveal that H2O-occupied Mo sites on the surface of IrMo could effectively optimize the free energies of *H2O and *OH, thereby enable IrMo following the so-called bifunctional mechanism both in alkaline HER/HOR electrolysis.
► Evapotranspiration (
ET) over much dry desert steppe was investigated.
► ET closely followed the variation in soil water content (
SWC) and leaf area index. ► Crop coefficient (Kc) was strongly ...controlled by
SWC,
RH, and
Rn.
► ET model derived from
Kc method was developed, showing good performance.
The magnitude and seasonal dynamics of evapotranspiration (
ET) over a temperate desert steppe in Inner Mongolia, China, were investigated during a growing season (from 1st May to 15th October 2008) using the eddy covariance (EC) technique. Diurnal variations of latent heat flux (
LE) at different phenological stages showed similar patterns with the peak value around noon. The sensible heat flux dominated the latent heat flux at midday during the whole growing season. Seasonal variation in
ET followed closely the variation in soil water content (
SWC) and leaf area index (
LAI). The maximum daily
ET rate was 3.8
mm
day
−1. Cumulative
ET during the study period estimated directly by EC method was 150.9
mm, exceeding the precipitation (
PPT) received at the site during the same period (133.0
mm) by 13.4%. The daily crop coefficient (
Kc, calculated as the ratio of the measured
ET (from the EC system) to the reference
ET (from the Penman–Monteith model)) also showed a distinct seasonal pattern, however its value on average was considerable lower (0.17) during the measurement period than the results reported from other grasslands, suggesting that this steppe was strongly affected by the deficit of available water.
SWC was the most important environmental factor controlling
ET in this steppe. The correlation analysis between daily
Kc and its major environmental controls indicated that
SWC, relative humidity (
RH), and net radiation (
Rn) were the major explanatory variables for daily
Kc. Daily
Kc showed a linear increase with
SWC and
Rn, and an exponential increase with
RH. Thus, a daily
Kc model would be developed as a function of
SWC,
RH, and
Rn. An empirical daily
ET model derived from the FAO 56 crop coefficient approach was developed based on this daily
Kc model and the Penman–Monteith model. This
ET model was validated by the data from the growing season in 2009, and showed a good consistency between the simulated and the measured
ET values. Based on the developed
ET model, an alternative
ET model with the variable of
SWC replaced by
PPT was established, which may have the advantage of
ET estimation under
PPT more easily available than
SWC.
Carbonyl sulfide (COS) is a tracer of ecosystem photosynthesis that can advance carbon cycle research from leaf to global scales; however, a range of newly reported caveats related to sink/source ...strength of various ecosystem components hinder its application. Using comprehensive eddy‐covariance and chamber measurements, we systematically measure ecosystem contributions from leaf, stem, soil, and litter and were able to close the ecosystem COS budget. The relative contributions of nonphotosynthetic components to the overall canopy‐scale flux are relatively small (~4% during peak activity season) and can be independently estimated based on their responses to temperature and humidity. Converting COS to photosynthetic CO2 fluxes based on the leaf relative uptake of COS/CO2, faces challenges due to observed daily and seasonal changes. Yet, this ratio converges around a constant value (~1.6), and the variations, dominated by light intensity, were found unimportant on a flux‐weighted daily time‐scale, indicating a mean ratio of daytime gross‐to‐net primary productivity of ~2 in our ecosystem. The seasonal changes in the leaf relative uptake ratio may indicate a reduction in mesophyll conductance in winter, and COS‐derived canopy conductance permitted canopy temperature estimate consistent with radiative skin temperature. These results support the feasibility of using COS as a powerful and much‐needed means of assessing ecosystem function and its response to change.
Carbonyl sulfide (COS) is a potentially powerful tracer of photosynthesis and canopy conductance. We measured ecosystem contributions of COS from leaf, stem, soil and litter in a lemon orchard over the seasonal cycle, and were able to close the ecosystem COS budget, and show good agreement of COS derived GPP, canopy conductance, and canopy skin temperature with corresponding indirect estimates. Our results support the feasibility of the COS application to ecosystem process studies.
Arid grassland ecosystems have significant interannual variation in carbon exchange; however, it is unclear how environmental factors influence carbon exchange in different hydrological years. In ...this study, the eddy covariance technique was used to investigate the seasonal and interannual variability of CO₂ flux over a temperate desert steppe in Inner Mongolia, China from 2008 to 2010. The amounts and times of precipitation varied significantly throughout the study period. The precipitation in 2009 (186.4 mm) was close to the long-term average (183.9±47.6 mm), while the precipitation in 2008 (136.3 mm) and 2010 (141.3 mm) was approximately a quarter below the long-term average. The temperate desert steppe showed carbon neutrality for atmospheric CO₂ throughout the study period, with a net ecosystem carbon dioxide exchange (NEE) of -7.2, -22.9, and 26.0 g C m⁻² yr⁻¹ in 2008, 2009, and 2010, not significantly different from zero. The ecosystem gained more carbon in 2009 compared to other two relatively dry years, while there was significant difference in carbon uptake between 2008 and 2010, although both years recorded similar annual precipitation. The results suggest that summer precipitation is a key factor determining annual NEE. The apparent quantum yield and saturation value of NEE (NEE(sat)) and the temperature sensitivity coefficient of ecosystem respiration (R(eco)) exhibited significant variations. The values of NEE(sat) were -2.6, -2.9, and -1.4 µmol CO₂ m⁻² s⁻¹ in 2008, 2009, and 2010, respectively. Drought suppressed both the gross primary production (GPP) and R(eco), and the drought sensitivity of GPP was greater than that of R(eco). The soil water content sensitivity of GPP was high during the dry year of 2008 with limited soil moisture availability. Our results suggest the carbon balance of this temperate desert steppe was not only sensitive to total annual precipitation, but also to its seasonal distribution.
Drought is one of the main environmental factors limiting plant growth and development. Pennisetum purpureum Schum. was used to explore the mitigation effects of exogenous strigolactone (SL) on ...drought stress during the seedling stage. The effects of different concentrations (1, 3, 5, and 7 μmol·L
) of SL on the photosynthesis characteristics, growth performance, and endogenous abscisic acid (ABA) of P. purpureum under drought stress were studied.
Exogenous SL could effectively alleviate the inhibitory effect of drought stress on P. purpureum growth. Compared with drought stress, the net photosynthesis rate, stomatal conductance, transpiration rate, and water-use efficiency of the leaves of P. purpureum after SL treatment significantly increased, thereby exerting a significant mitigation effect on the decrease in photosystem II maximum photochemical efficiency and the performance index based on light absorption caused by drought. Moreover, the exogenous application of SL can effectively increase the fresh and dry weight of the leaves and roots and the main-root length. After applying SL for 120 h, the ABA content of P. purpureum decreased significantly. The activity of key enzymes of photosynthesis significantly increased after 48 h of external application of SL to P. purpureum.
SL treatment can improve the photosynthesis performance of P. purpureum leaves under drought conditions and increase the antioxidant capacity of the leaves, thereby reducing the adverse effects of drought, promoting the growth of P. purpureum, and effectively improving the drought resistance of P. purpureum.
Giant Juncao is often used as feed for livestock because of its huge biomass. However, drought stress reduces forage production by affecting the normal growth and development of plants. Therefore, ...investigating the molecular mechanisms of drought tolerance will provide important information for the improvement of drought tolerance in this grass.
A total of 144.96 Gb of clean data was generated and assembled into 144,806 transcripts and 93,907 unigenes. After 7 and 14 days of drought stress, a total of 16,726 and 46,492 differentially expressed genes (DEGs) were observed, respectively. Compared with normal irrigation, 16,247, 23,503, and 11,598 DEGs were observed in 1, 5, and 9 days following rehydration, respectively. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed abiotic stress-responsive genes and pathways related to catalytic activity, methyltransferase activity, transferase activity, and superoxide metabolic process. We also identified transcription factors belonging to several families, including basic helix-loop-helix (bHLH), WRKY, NAM (no apical meristem), ATAF1/2 and CUC2 (cup-shaped cotyledon) (NAC), fatty acyl-CoA reductase (FAR1), B3, myeloblastosis (MYB)-related, and basic leucine zipper (bZIP) families, which are important drought-rehydration-responsive proteins. Weighted gene co-expression network analysis was also used to analyze the RNA-seq data to predict the interrelationship between genes. Twenty modules were obtained, and four of these modules may be involved in photosynthesis and plant hormone signal transduction that respond to drought and rehydration conditions.
Our research is the first to provide a more comprehensive understanding of DEGs involved in drought stress at the transcriptome level in Giant Juncao with different drought and recovery conditions. These results may reveal insights into the molecular mechanisms of drought tolerance in Giant Juncao and provide diverse genetic resources involved in drought tolerance research.
With the explosive growth of online services, the Internet Data Center (IDC) has become an emerging load demand . The power consumption of IDCs are believed suitable for demand response (DR) purposes ...due to its temporal‐spatial flexibility properties. To what extent IDCs could be used as candidate DR resources to provide capacity support are dependent both on the technical property and the willingness of data end‐users . To address the above issue, this paper presents a methodological framework for quantifying the potential value of IDC‐based DR in distribution grids. To achieve this, the concept of capacity credit (CC) is introduced and extended into the IDC scenario. The proposed framework explicitly considered the impacts of uncertainty of user participation intention and the reliability of basic information in the DR process. A novel Z‐number based price elasticity uncertainty model is introduced, and a more realistic evaluation of IDC capacity credit is obtained. Finally, the effectiveness of the proposed model and method is illustrated on a modified IEEE‐33 node network, and the obtained results verify the significance of IDC‐based DR in enhancing the adequacy of supply in distribution grids.
This paper presents a methodological framework for quantifying the potential value of internet data center‐based demand response (DR) in smart distribution grids. The proposed framework explicitly considered the impacts of both uncertainty of user participation intention and the reliability of basic information in the DR process.
Evapotranspiration (ET) is an important component of the surface energy balance and hydrological cycle. In this study, the eddy covariance technique was used to measure ET of the semi-arid farmland ...ecosystem in the Loess Plateau during 2010 growing season (April to September). The characteristics and environmental regulations of ET and crop coefficient (Kc) were investigated. The results showed that the diurnal variation of latent heat flux (LE) was similar to single-peak shape for each month, with the largest peak value of LE occurring in August (151.4 W m(-2)). The daily ET rate of the semi-arid farmland in the Loess Plateau also showed clear seasonal variation, with the maximum daily ET rate of 4.69 mm day(-1). Cumulative ET during 2010 growing season was 252.4 mm, and lower than precipitation. Radiation was the main driver of farmland ET in the Loess Plateau, which explained 88% of the variances in daily ET (p<0.001). The farmland Kc values showed the obvious seasonal fluctuation, with the average of 0.46. The correlation analysis between daily Kc and its major environmental factors indicated that wind speed (Ws), relative humidity (RH), soil water content (SWC), and atmospheric vapor pressure deficit (VPD) were the major environmental regulations of daily Kc. The regression analysis results showed that Kc exponentially decreased with Ws increase, an exponentially increased with RH, SWC increase, and a linearly decreased with VPD increase. An experiential Kc model for the semi-arid farmland in the Loess Plateau, driven by Ws, RH, SWC and VPD, was developed, showing a good consistency between the simulated and the measured Kc values.
Rich biological information in sweat provides great potential for health monitoring and management. However, due to the complexity of sweat, the development of environmentally friendly green ...electronic products is of great significance to the construction of ecological civilization. This study utilized a simple combination of polystyrene sulfonate sodium (PSS) and filter paper (FP) to prepare cellulose materials coated with conductive polymers, developing an electrochemical sensor based on the modified materials. The mechanical and electrochemical properties of the fabricated PSS/FP membrane were optimized by adjusting the feeding dosage of PSS. The realized PSS/FP composite containing 7% PSS displayed good conductivity (9.1 × 10sup.−2 S/m), reducing electric resistance by 99.2% compared with the original FP membrane (6.7 × 10sup.−4 S/m). The stable current of the membrane in simulated sweat under different pH environments is highly correlated with the pH values. Additionally, when the membrane is exposed to simulated sweat with varying ion concentrations, the current signal changes in real time with the concentration variations. The response time averages around 0.3 s.
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