Porous TiFe_(2) intermetallic compound fabricated via elemental powder reactive synthesis

Porous intermetallics show potential in the field of filtration and separation as well as in the field of catalysis.Herein,porous Ti Fe2intermetallics were fabricated by the reactive synthesis of elemental powders.The phase transformation and pore formation of porous TiFe2intermetallics were investigated,and its corrosion behavior and hydrogen evolution reaction(HER)performance in alkali solution were studied.Porous TiFe2intermetallics with porosity in the range of 34.4%-56.4%were synthesized by the diffusion reaction of Ti and Fe elements,and the pore formation of porous TiFe2intermetallic compound is the result of a combination of the bridging effect and the Kirkendall effect.The porous TiFe2samples exhibit better corrosion resistance compared with porous 316L stainless steel,which is related to the formation of uniform nanosheets on the surface that hinder further corrosion,and porous TiFe2electrode shows the overpotential of 220.6 and 295.6 mV at 10 and 100 mA·cm-2,suggesting a good catalytic performance.The synthesized porous Fe-based intermetallic has a controllable pore structure as well as excellent corrosion resistance,showing its potential in the field of filtration and separation.

Soil properties drive the bacterial community to cadmium contamination in the rhizosphere of two contrasting wheat(Triticum aestivum L.)genotypes

Cadmium(Cd)bioavailability in the rhizosphere makes an important difference in grain Cd accumulation in wheat.Here,pot experiments combined with 16S rRNA gene sequencing were conducted to compare the Cd bioavailability and bacterial community in the rhizosphere of two wheat(Triticum aestivum L.)genotypes,a low-Cd-accumulating genotype in grains(LT)and a high-Cd-accumulating genotype in grains(HT),grown on four different soils with Cd contamination.Results showed that there was non-significant difference in total Cd concentration among four soils.However,except for black soil,DTPA-Cd concentrations in HT rhizospheres were higher than those of LT in fluvisol,paddy soil and purple soil.Results of 16S rRNA gene sequencing showed that soil type(52.7%)was the strongest determinant of root-associated community,while there were still some differences in rhizosphere bacterial community composition between twowheat genotypes.Taxa specifically colonized in HT rhizosphere(Acidobacteria,Gemmatimonadetes,Bacteroidetes and Deltaproteobacteria)could participate inmetal activation,whereas LT rhizosphere was highly enriched by plant growth-promoting taxa.In addition,PICRUSt2 analysis also predicted high relative abundances of imputed functional profiles related to membrane transport and amino acid metabolism in HT rhizosphere.These results revealed that the rhizosphere bacterial community may be an important factor regulating Cd uptake and accumulation in wheat and indicated that the high Cd-accumulating cultivar might improve Cd bioavailability in the rhizosphere by recruiting taxa related to Cd activation,thus promoting Cd uptake and accumulation.

Carbon Dioxide Concentrations and Light Levels on Growth and Mineral Nutrition of Juvenile Cacao Genotypes

In many countries cacao (Theobroma cacao L.) is invariably grown as an understory crop in agroforestry types of cropping systems and subjected to low levels photosynthetic photon flux density (PPFD) due to presence of large number of upper story shade trees with poorly managed canopy structure. In recent years carbon dioxide concentration in the atmosphere is steadily increasing and it is unclear what impact this will have on performance of cacao grown under shade of upper story shade trees. A climatically controlled greenhouse experiment was undertaken to evaluate the effects of ambient and elevated carbon dioxide (400 and 700 μmol·mol-1) and three levels of PPFD (100, 200, and 400 μmol·m-2·s-1) on growth, and macro- and micronutrient use efficiency of three genetically contrasting cacao genotypes (CCN 51, VB 1117 and NO 81). Intraspecific variations were observed in cacao genotypes for growth parameters at ambient to elevated carbon dioxide and low to adequate levels of PPFD. With the exceptions of total root length and leaf area, irrespective of carbon dioxide and PPFD levels, all three genotypes showed significant differences in all the growth parameters. For all the cacao genotypes, increasing PPFD from 100 to 400 μmol·m-2·s-1 and carbon dioxide from 400 to 700 μmol·mol-1 increased overall growth parameters such as leaf, shoot and root biomass accumulation, stem height, leaf area, relative growth rate and net assimilation rate. Irrespective of carbon dioxide and PPFD, invariably genotypes differed significantly in macro-micronutrient uptake parameters such as concentration, uptake, influx, transport and use efficiency. With few exceptions, raising PPFD from 100 to 400 μmol·m-2·s-1 and carbon dioxide from 400 to 700 μmol·mol-1 increased nutrient use efficiency for all the cacao genotypes. Elevated carbon dioxide and adequate PPFD are beneficial in improving cacao growth and mineral nutrient uptake and use efficiency.

A Comparative Study of the Cellular Microscopic Characteristics and Mechanisms of Maize Seedling Damage from Superabsorbent Polymers

Superabsorbent polymers(SAPs) as soil moisture conditioners have been increasingly used in agriculture, but conflicting results were reported regarding the effects of SAPs on crop growth. In this study, both laboratory cultivation and analysis were conducted to investigate the effects of different SAPs on the growth and physiology of crops under water-saving agricultural practices. Maize(Zea mays L.) seedlings were cultivated using distilled water or three different SAP hydrogels, sodium polyacrylate(SP), potassium polyacrylate(PP), and sodium polyacrylate embedded with phosphate rock powder(SPP), as growth media. Growth characteristics of the model plant and damage were assessed using scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results showed that both the SP and PP treatments had pronounced negative effect on the hydrogels of growth of maize seedlings. The SPP treatment appeared to facilitate the stem-leaf growth and had no obvious adverse effect on root growth. All the three hydrogel treatments caused varying degrees of damage to the organizational structure and cellular morphology of the roots, with the SP and PP treatments causing the most severe damage; the membrane system of root cells was damaged by both SP and PP treatments. An excessive accumulation of sodium and reduction of calcium occurred in the roots may be responsible for the observed damage to the cell membrane system, which, in turn, may have promoted the wilting of the cells.

Heavy metal phytoextraction by Sedum alfredii is affected by continual clipping and phosphorus fertilization amendment

Improving the efficacy of phytoextraction is critical for its successful application in metal contaminated soils. Mineral nutrition affects plant growth and metal absorption and subsequently the accumulation of heavy metal through hyper-accumulator plants. This study assessed the effects of di-hydrogen phosphates （KH2PO4, Ca（H2PO4）2, NaH2PO4 and NH4H2PO4） application at three levels （22, 88 and 352 mg P/kg soil） on Sedum alfredii growth and metal uptake by three consecutive harvests on aged and Zn/Cd combined contaminated paddy soil. The addition of phosphates （P） significantly increased the amount of Zn taken up by S. alfredii due to increased shoot Zn concentration and dry matter yield （DMY） （P 〈 0.05）. The highest phytoextraction of Zn and Cd was observed in KH2PO4 and NH4H2PO4 treatment at 352 mg P/kg soil. The amount of Zn removed by phytoextraction increased in the order of 1st clipping 〈 2nd clipping 〈 3rd clipping, and for Cd extraction the order was 2nd clipping 〈 1st clipping 〈 3rd clipping. These results indicate that the application of P fertilizers coupled with multiple cuttings can enhance the removal of Zn and Cd from contaminated soils by S. alfredii, thus shortening the time needed for accomplishing remediation goals.

Electrochemical performances of NiO/Ni2N nanocomposite thin film as anode material for lithium ion batteries

Despite the high specific capacities,the practical application of transition metal oxides as the lithium ion battery(LIB)anode is hindered by their low cycling stability,severe polarization,low initial coulombic efficiency,etc.Here,we report the synthesis of the NiO/Ni2N nanocomposite thin film by reactive magnetron sputtering with a Ni metal target in an atmosphere of 1 vol.% O2 and 99 vol.%N2.The existence of homogeneously dispersed nano Ni2N phase not only improves charge transfer kinetics,but also contributes to the one-off formation of a stable solid electrolyte interphase(SEI).In comparison with the NiO electrode,the NiO/Ni2N electrode exhibits significantly enhanced cycling stability with retention rate of 98.8%(85.6%for the NiO electrode)after 50 cycles,initial coulombic efficiency of 76.6%(65.0%for the NiO electrode)and rate capability with 515.3 mA·h·g^−1(340.1 mA·h·g^−1 for the NiO electrode)at 1.6 A·g^−1.

Morphological and Physiological Responses of Plants to Cadmium Toxicity: A Review

Cadmium(Cd) contamination has posed an increasing challenge to environmental quality and food security. In recent years,phytoremediation has been particularly scrutinized because it is cost-effective and environmentally friendly, especially the use of metal-hyperaccumulating plants to extract or mine heavy metals from polluted soils. Under Cd stress, responses of hyperaccumulator and non-hyperaccumulator plants differ in morphological responses and physiological processes such as photosynthesis and respiration,uptake, transport, and assimilation of minerals and nitrogen, and water uptake and transport, which contribute to their ability to accumulate and detoxify Cd. This review aims to provide a brief overview of the recent progresses in the differential responses of hyperaccumulator and non-accumulator plants to Cd toxicity in terms of growth and physiological processes. Such information might be useful in developing phytoremediation technology for contaminated soils.

Effects of a New-Type Cleaning Agent and a Plant Growth Regulator on Phytoextraction of Cadmium from a Contaminated Soil

In China, great efforts are being made to remediate farmlands polluted by heavy metals. In this study, a soil pot experiment was conducted to examine the effects of a new-type cleaning agent, methylglycinediacetic acid(MGDA), and a plant growth regulator(PGR), diethl aminoethyl hexanoate(DA-6), on plant growth and extraction and detoxification of cadmium(Cd) by ryegrass. The results showed that foliar spray of DA-6 alone improved plant growth, with root length and shoot dry biomass increased by 38.5%–58.6% and 71.1%–89.3%, respectively, whereas addition of MGDA alone decreased root length and shoot dry biomass by 10.3%–18.6%and 9.1%–21.8%, respectively. Diethl aminoethyl hexanoate promoted the binding of Cd to cell walls and thus alleviated the toxicity of Cd and/or MGDA to plants. Applications of DA-6 and/or MGDA resulted in a significant increase in Cd extraction efficiency(P < 0.05), and the efficiency decreased in the order of MGDA + DA-6 > DA-6 > MGDA. The treatment of MGDA + DA-6 achieved 2.2%, 1.7%, and 0.8% Cd extraction efficiency by ryegrass in soils spiked with 25, 50, 100 mg Cd kg^(-1), respectively. Therefore,treatment of MGDA + DA-6 could be an efficient method for enhancing phytoremediation of Cd-contaminated soil by ryegrass.

Mechanisms of Exogenous Nitric Oxide and 24-Epibrassinolide Alleviating Chlorosis of Peanut Plants Under Iron Deficiency

Iron(Fe) is a crucial transition metal for all living organisms including plants; however, Fe deficiency frequently occurs in plant because only a small portion of Fe is bioavailable in soil in recent years. To cope with Fe deficiency, plants have evolved a wide range of adaptive responses from changes in morphology to altered physiology. To understand the role of nitric oxide(NO) and 24-epibrassinolide(EBR) in alleviating chlorosis induced by Fe deficiency in peanut(Arachis hypogaea L.) plants, we determined the concentration of chlorophylls, the activation, uptake, and translocation of Fe, the activities of key enzymes, such as ferric-chelate reductase(FCR),proton-translocating adenosine triphosphatase(H^+-ATPase), and antioxidant enzymes, and the accumulation of reactive oxygen species(ROS) and malondialdehyde(MDA) of peanut plants under Fe sufficiency(100 μmol L^(-1)ethylenediaminetetraacetic acid(EDTA)-Fe) and Fe deficiency(0 μmol L^(-1)EDTA-Fe). We also investigated the production of NO in peanut plants subjected to Fe deficiency with foliar application of sodium nitroprusside(SNP), a donor of NO, and/or EBR. The results showed that Fe deficiency resulted in severe chlorosis and oxidative stress, significantly decreased the concentration of chlorophylls and active Fe, and significantly increased NO production. Foliar application of NO and/or EBR increased the activity of antioxidant enzymes, superoxide dismutase,peroxidase, and catalase, and decreased the ROS and MDA concentrations, thus enhancing the resistance of plants to oxidative stress.Application of NO also significantly increased Fe translocation from the roots to the shoots and enhanced the transfer of Fe from the cell wall fraction to the cell organelle and soluble fractions. Consequently, the concentrations of available Fe and chlorophylls in the leaves were elevated. Furthermore, the activities of H^+-ATPase and FCR were enhanced in the Fe-deficient plants. Simultaneously,there was a significant increase in NO production, especially in the plants that received NO, regardless of Fe supply. These suggest that NO or EBR, and, especially, their combination are effective in alleviating plant chlorosis induced by Fe deficiency.