Nitrogen‐doped self‐shrinking porous 3D graphene capacitor deionization electrode

Traditional three‐dimensional (3D) graphene has a large pore structure, which makes the graphene structure not well interact with the anion and cation during the desalination process, thereby restricting the capacitive deionization (CDI) ability of the 3D graphene. In this work, we prepared a nitrogen‐doped self‐shrinking porous 3D graphene electrode by adding a pyrrole monomer to a graphene oxide solution, which was then applied to a CDI electrode. The results show that the electrochemical performance of the as‐prepared nitrogen‐doped self‐shrinking porous 3D graphene (NSPG) is significantly improved. Compared with traditional 3D graphene, NSPG has a denser pore structure with a larger specific surface area, thus exhibiting a good CDI performance: The NSPG electrode has an electroadsorption capacity of 13.16 mg/g.     

Defect structure and transport properties in (Co,Cu,Mg,Ni,Zn)O high entropy oxide

The defect structure and chemical diffusion in the (Co,Cu,Mg,Ni,Zn)O high entropy oxide were investigated. The material was synthesized in a form of pellets by means of a solid-state reaction, through sintering the mixture of composing oxides at 1273 K for 20 h, followed by the air quenching. The presence of the single-phase, high entropy solid solution structure was confirmed with the use of SEM + EDS and XRD methods and later confirmed after each of the experimental steps. The modification of the standard marker experiment was applied, to determine the predominantly disordered sublattice, which turned out to be the anionic one. The nonstoichiometry and its dependence on the oxygen partial pressure were investigated by means of the thermogravimetric method. The results allowed establishing the (Co,Cu,Mg,Ni,Zn)O_1-y general formula, with values of y reaching values as high as 0.07 under low oxygen partial pressures. The non-logarithmic character of the obtained pressure dependence suggests the presence of a complex structure of interacting point defects. The chemical diffusion coefficient was also determined, based on the measured re-equilibration kinetics. The obtained values of diffusivity are within the range typical for the transition metal oxides, do not confirm the presence of the sluggish diffusion effect in high entropy oxides. The established strong dependence of the chemical diffusion coefficient on the p(O₂), further confirms the presence of the complex defect structure.     

Nitrogen Removal Performance of Denitrifying Ammonium Oxidation System in Treating Sulfamethoxazole-laden Secondary Wastewater Effluent

In this study,nitrogen removal performance of the denitrifying ammonium oxidation(DAO)process was investigated when treating sulfamethoxazole(SMX)-laden secondary wastewater effluent.The influent SMX concentration showed negligible effect on efficiencies for removal of nitrate and COD.However,the ammonium ions removal rate was moderately reduced,when the influent SMX concentration in wastewater reached 6 mg/L.Total nitrogen removal efficiency remained as high as 76.77%towards the day 158 at the end of experiment.Candidatus_Brocadia and Candidatus_Kuenenia were the functional anammox strains.The unclassified_f__Rhodobacteraceae sp.was predominant heterotrophic denitrifying strain in the studied reactor.The concentrations of soluble extracellular polymeric substances in sludge obviously increased from 16.76 mg/g VSS to 32.31 mg/g VSS,which might protect the nitrogen removal strains from high-concentration SMX.This result provides a theoretical and technical foundation for the application of denitrifying ammonium oxidation process in treating sulfamethoxazole-laden secondary wastewater effluent.     

Impact of air contamination by NOx on the performance of high temperature PEM fuel cells

High temperature PEM fuel cells show enhanced tolerances regarding fuel impurities like CO for use in various applications. However, the impact of air impurities like NO_x on the cell behavior is not completely understood yet. This study provides systematic investigation during 500 h of operation in presence of cathode air containing 10 ppm NO or NO₂. Nitrogen oxides provoke a strongly and linearly decreasing voltage of 245.3 ± 18.5 μV h⁻¹ and highly comparable damage that verifies similar HT-PEMFC degradation via both oxides. Cyclic voltammetry and electron microscopy reveal the loss of electrochemical catalyst surface by selectively poisoned surface and enforced catalyst particle growth. Impedance spectroscopy reveals besides increased electrode charge transfer resistances an affected proton conductivity. In contrast, SO₂/NO₂ impurity mixture in real occurring ratio causes less voltage decay due to a positive SO₂ impact through H₂SO₄ formation causing further shown and discussed effects like nitrate formation and discharge.     

An Engineering Approach for Estimating the Formation of Nitric Oxide from Fuel‐Nitrogen

Explicit approximate equations for estimating the conversion factor of fuel‐nitrogen into nitric oxide are presented. They depend on the fuel‐nitrogen mole fraction, the initial nitric oxide mole fraction, and the kinetics‐equilibrium mole fraction of nitric oxide. This last parameter expresses a limiting value of fuel‐nitrogen conversion; it includes the complex nitrogen chemistry and depends thus on combustion conditions. Experimental results demonstrate that the kinetics‐equilibrium mole fraction for fuel‐lean and high‐temperature conditions can be well estimated by the chemical‐equilibrium mole fraction, but for lower temperatures the kinetics‐equilibrium mole fraction has to be described by other correlations.     

Sol-gel processed highly (100)-textured (K,Na)NbO3-based lead-free thin films: Effect of pyrolysis temperature

Recently, lead-free piezoelectric thin films have received increasing attention due to the growing demands for mircoelectromechanical systems and the significant progress in lead-free piezoelectric research. Here, potassium sodium niobate [(K, Na)NbO₃ (KNN)]-based thin films were fabricated via a sol-gel method. The effects of pyrolysis temperature on the resulting microstructure and electrical properties of KNN-based films were investigated. The KNN-based film pyrolyzed at 550°C and annealed at 700°C shows a dominant (100) orientation with a high texturing degree of 91.7%. The microstructures, morphologies, piezo- and ferroelectric properties of the KNN-based films were discussed in association with different pyrolysis temperatures. The crystallization mechanism of the (100) textured KNN-based thin films was elaborated in detail.     

Association of aerobic anoxygenic phototrophs and zebra mussels,Dreissena polymorpha,within the littoral zone of Lake Winnipeg

While nutrient loading has affected all levels of Lake Winnipeg’s ecology, its greatest influence has likely been on the microbial community. In addition to eutrophication, zebra mussels (Dreissena polymorpha) have recently invaded the ecosystem and threaten food web dynamics. Their filter-feeding predation and association with bacteria, specifically phototrophs, was investigated. A sampling trip to Lake Winnipeg in October 2017, focused on the isolation, enumeration, and identification of aerobic anoxygenic phototrophs in littoral water, sediment, and tissues of mussels. Gimli, Patricia, and Grand beaches, separated by >15 km across the South Basin, had similar bacterial counts when cultivated on rich organic, BG-11, purple non-sulphur, and K₂TeO₃-supplemented media. Culture-based enumeration on rich organic medium revealed 1.74% of heterotrophs from littoral waters were aerobic anoxygenic phototrophs, and represented 13.98% within sediments. In contrast, 0.48, 1.15, and 0.16% of cultured heterotrophs were aerobic anoxygenic phototrophs within zebra mussel gill, gut, and gonadal tissues, respectively. High-throughput sequencing of bacterial 16S V4 rDNA maintained similar trends in respective bivalve organs, where 0.22, 1.13, and 0.20% of total 16S genes belonged to these phototrophs. Several Sphingomonadaceae isolates were recovered from gut tissues, all with filamentous morphology large enough for predation. Bioaccumulation of metals was also studied in D. polymorpha. All tested associated aerobic anoxygenic phototrophs were capable of resisting the metalloid oxide tellurite. The consistent distribution of aerobic anoxygenic phototrophs within microbial communities across Lake Winnipeg, and their predominance in the gut tissues of zebra mussels suggested bacterial consumption by this invasive species.     

Structure and Properties of Nonstoichiometric Y1-xNbxO1.5+x for Thermal Barrier Coatings

Understanding the effect of nonstoichiometry on material properties is of critical importance for the Thermal Barrier Coatings (TBCs) application. In this work, the effect of nonstoichiometry was systematically investigated in Y₃NbO₇, a recently identified promising TBCs material for next-generation gas turbine engines. The results show that the nonstoichiometry effect mediates the microstructure, mechanical properties, thermophysical properties, oxygen ionic conductivity and optical transmittance. The results suggest that the oxygen ionic conductivity is correlated to the mass diffusion in the oxygen-deficient fluorite oxides Y_1-xNb_xO_1.5+x. The stoichiometric composition Y₃NbO₇, with the lowest thermal conductivity and slowest mass diffusion in Y_1-xNb_xO_1.5+x series, is optimal for the TBCs application, which can be of relevance for TBCs material design and coating fabrication.     

Effect of Cultivation Parameters on Fermentation and Hydrogen Production in the Phylum Thermotogae

The phylum Thermotogae is composed of a single class (Thermotogae), 4 orders (Thermotogales, Kosmotogales, Petrotogales, Mesoaciditogales), 5 families (Thermatogaceae, Fervidobacteriaceae, Kosmotogaceae, Petrotogaceae, Mesoaciditogaceae), and 13 genera. They have been isolated from extremely hot environments whose characteristics are reflected in the metabolic and phenotypic properties of the Thermotogae species. The metabolic versatility of Thermotogae members leads to a pool of high value-added products with application potentials in many industry fields. The low risk of contamination associated with their extreme culture conditions has made most species of the phylum attractive candidates in biotechnological processes. Almost all members of the phylum, especially those in the order Thermotogales, can produce bio-hydrogen from a variety of simple and complex sugars with yields close to the theoretical Thauer limit of 4 mol H₂/mol consumed glucose. Acetate, lactate, and L-alanine are the major organic end products. Thermotagae fermentation processes are influenced by various factors, such as hydrogen partial pressure, agitation, gas sparging, culture/headspace ratio, inoculum, pH, temperature, nitrogen sources, sulfur sources, inorganic compounds, metal ions, etc. Optimization of these parameters will help to fully unleash the biotechnological potentials of Thermotogae and promote their applications in industry. This article gives an overview of how these operational parameters could impact Thermotogae fermentation in terms of sugar consumption, hydrogen yields, and organic acids production.     

Identification of the miRNAs and their target genes involved in fresh-cut potato browning inhibition by nitrogen

Browning decreases the quality and shortens the shelf life of fresh-cut potato, causing enormous economic losses. This study indicated that nitrogen treatment could inhibit this browning process. However, whether microRNAs (miRNAs) are involved in inhibiting the fresh-cut potato browning by nitrogen remains unclear. Therefore, nine small RNA libraries were constructed and performed high-throughput sequencing using fresh-cut potatoes from control and nitrogen-treated for 1 h groups at 25 °C to identify the miRNAs and their target genes involved in fresh-cut potato browning inhibition by nitrogen. The results revealed that four common differentially expressed miRNAs (DEmiRNAs) were identified as associated with browning. The correlation analysis indicated that fresh-cut potato browning was closely related to the expression of DEmiRNAs and their potential target genes. The miR172d targeting APETALA2/ethylene response factor and phospholipase D, miR482e targeting ATPase GET3-like, and PC-3p-17015_391 targeting stachyose synthase are vital in the nitrogen inhibited fresh-cut potato browning by regulating the ethylene signalling pathway, membrane lipid metabolic process, ATPase activity, and carbohydrate metabolic process. This study provides new insights into fresh-cut potato browning inhibition and helps to improve the quality of fresh-cut potato using nitrogen.