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Enhancing the thermal safety of hydrophobic SiO 2 aerogels (SAs) is crucial for its practical thermal insulation applications. Here, we explore a facile method to enhance the thermal safety of hydrophobic SAs with the introduction of ammonium polyphosphate intercalated layered double hydroxide (APP-LDH). The obtained results show that as-produced APP-LDH/SA composites maintain excellent fundamental properties, including low density (0.14–0.16 g/cm3), high porosity (92.8–93.5 %), high specific surface area (680.0–762.6 m2/g), and low thermal conductivity (25.3–26.9 mW/m/K). Notably, APP-LDH effectively inhibits the thermal oxidation decomposition of SAs. In comparison to pristine SAs and those modified solely with LDH, the APP-LDH/SA composites exhibit significantly improved thermal stability. The gross calorific value of the APP-LDH/SA-20 % (i.e., containing 20 wt% APP-LDH) decreases by 13.9 % and 5.2 % compared with that of neat SAs and SAs modified solely with 20 wt% LDH, respectively. The improved thermal stability and reduced gross calorific value completely confirm the enhancement of the thermal safety of the APP-LDH/SA composites. This work provides a simple method to improve the thermal safety of hydrophobic SAs, which expands the thermal insulation application scenarios of SAs. [ABSTRACT FROM AUTHOR]

• The start-up of filters for NH 4 + and Mn2+ removal by catalytic oxidation was studied. • Different combinations of oxidants and reductants were introduced during the start-up period. • Comparison of catalytic oxidation activity of MnOx follows: Mn7+→MnO x ˃Mn7+→MnO x ←Mn2+ ˃ Mn2+→MnO x. • Potassium permanganate was more conducive to the formation of active species. A pilot-scale filtration system was adopted to prepare filter media with catalytic activity to remove manganese (Mn2+) and ammonium (NH 4 +-N). Three different combinations of oxidants (KMnO 4 and K 2 FeO 4) and reductants (MnSO 4 and FeCl 2) were used during the start-up period. Filter R3 started up by KMnO 4 and FeCl 2 (Mn7+→MnO x) exhibited excellent catalytic property, and the NH 4 +-N and Mn2+ removal efficiency reached over 80% on the 10th and 35th days, respectively. Filter R1 started up by K 2 FeO 4 and MnSO 4 (MnO x ←Mn2+) exhibited the worst catalytic property. Filter R2 started up by KMnO 4 and MnSO 4 (Mn7+→MnO x ←Mn2+) were in between. According to Zeta potential results, the Mn-based oxides (MnO x) formed by Mn7+→MnO x performed the highest pH IEP and pH PZC. The higher the pH IEP and pH PZC , the more unfavorable the cation adsorption. However, it was inconsistent with its excellent Mn2+ and NH 4 +-N removal abilities, implying that catalytic oxidation played a key role. Combined with XRD and XPS analysis, the results showed that the MnO x produced by the reduction of KMnO 4 showed early formation of buserite crystals, high degree of amorphous, high content of Mn3+ and lattice oxygen with the higher activity to form defects. The above results showed that MnO x produced by the reduction of KMnO 4 was more conducive to the formation of active species for catalytic oxidation of NH 4 +-N and Mn2+ removal. This study provides new insights on the formation mechanisms of the active MnO x that could catalytic oxidation of NH 4 +-N and Mn2+. [Display omitted] [ABSTRACT FROM AUTHOR]

The production of hydrogen via photocatalytic water splitting is one of the most promising technologies for obtaining chemical energy from direct solar energy while maintaining the least possible waste and pollutants. In this paper, we obtain the kinetic parameters necessary for the design of a photoreactor for photolysis and photocatalysis of ammonium sulfite solution. For the case of photolysis, we obtain the kinetics for the effect of changing the pH on the produced amount of hydrogen. For the case of photocatalysis, the intrinsic kinetic parameters of photocatalysis of water splitting reaction of ammonium sulfite and water in the presence of cadmium sulfide as a catalyst under solar radiation was inspected by developing MATLAB codes that can predict the kinetics based on the results of experimental work done. The resulted kinetics are compared to experimental work already done. These obtained kinetic parameters provide guidance for the design or scale-up of a solar photoreactor. [ABSTRACT FROM AUTHOR]

It is generally accepted that hydrogen is generated by ferrous iron oxidation and/or water radiolysis but no attempt has been done so far to explain the origin of the nitrogen that is associated to 'hydrogen systems' such as those located in Brazil and Oman and New Caledonian ophiolites. We carried out 25–300 °C geochemical equilibrium calculations on model water and water-mineral systems including ammonium (NH 4 +) to see if this ion could be a 'precursor' in the generation of hydrogen and/or nitrogen. The considered minerals of the water-mineral systems were the magnetite-hematite or fayalite-magnetite-quartz redox-buffering assemblages. The water systems including NH 4 + only or NH 4 + and ferrous iron co-generate hydrogen and nitrogen through the ammonium decomposition reaction: NH 4 + = 1.5 H 2 + 0.5 N 2 + H+ In the water-mineral systems, hydrogen is generated by the magnetite and fayalite ferrous iron oxidation while nitrogen is generated independently by the hematite and magnetite ferric iron reduction by NH 4 +: 3 Fe3+ + NH 4 + = 0.5 N 2 + 3 Fe2+ + 4 H+ With magnetite-hematite, the produced gas is mainly composed of nitrogen. At low temperature with fayalite-magnetite-quartz, the produced gas is mainly composed of hydrogen; approaching 300 °C, and with a sufficient initial ammonium stock, a significant amount of nitrogen is produced to form a mixed gas. If we consider low (magnetite-hematite) or high (fayalite-magnetite-quartz) reducing conditions occurring respectively within the central or peripheral zones of the hydrogen systems, NH 4 + passing through and reacting with these two kinds of redox environments could explain why the central zones release mainly hydrogen (with some amounts of nitrogen) and why mainly nitrogen is emitted at the peripheries. • Modeling of ammonium oxidation in redox-unbuffered and -buffered aqueous systems. • Hydrogen and nitrogen co-generation through ammonium decomposition. • Nitrogen generation through ferric iron reduction by ammonium. • Hydrogen to nitrogen gas ratios as function of redox conditions. • Explanation of hydrogen and nitrogen association within natural hydrogen seepages. [ABSTRACT FROM AUTHOR]

• Drying of solid digestate was investigated in thin-layer at a laboratory-scale. • The kinetics of ammonium degradation and drying exhibited a similar characteristic. • Both processes occured in three similar distinguishable periods. • In the first reaction period, NH 4 -N degradation is a first-order chemical reaction. • The development of the pH value clearly followed the reaction course. Fundamental knowledge of the drying behavior and ammonia emission from digestate is required in order to properly design efficient drying processes. In this study, laboratory-scale drying experiments with two different digestates (D1 and D2) were conducted at four different drying temperatures (50, 60, 70, and 80 °C). The solid digestate D1 mainly consisted of plant silage (88.7%), while D2 comprised primarily of manure (55.9%). The drying experiments were performed in a controlled drying chamber using relatively small-sized samples of digestate (30 g for D1, 37 g for D2). These samples were characterized by an initial moisture content of about 74% wb (D1) and 78% wb (D2). This sample size mass was deliberately chosen to ensure homogeneous drying conditions within a thin layer and to facilitate precise laboratory quality measurements of parameters including water content, nitrogen contents (N-total, NH 4 -N), and pH values before and after the drying process. Both types of digestate exhibited a similar kinetics of drying and ammonium degradation. The first period of constant drying rate was followed by two periods with decreasing rates. Similarly, the ammonium degradation was characterized by three periods with decreasing reaction rates. Considering only the first reaction period herein, ammonium degradation was determined as a first-order reaction. The activation energy for this reaction period was obtained to be 20.00 kJ mol−1 for digestate D1 and 18.44 kJ mol−1 for digestate D2. The results of this study may serve as a basis for the conceptualization and design of optimized, continuous drying processes tailored to digestate materials. [ABSTRACT FROM AUTHOR]

The biodegradation of perchlorate (ClO 4 -) in contaminated environments often requires extra electron donors and carbon sources. This study investigates the use of ambient aerobic pretreatment technology combined with anaerobic fermentation of food waste to produce fermentation broth of food waste (FBFW) and enhance ClO 4 - biodegradation capacity. The results demonstrated that FBFW, prepared through aerobic pretreatment, exhibited excellent performance in ClO 4 - biodegradation. With an electron donor-to-acceptor ratio of 1.2, a remarkable ClO 4 - removal efficiency of 92.38% was achieved at 72 ​h when using FBFW after a 6-day aerobic pretreatment. This can be attributed to the higher proportion of lactic acid and lower ammonium concentration. Furthermore, FBFW, serving as an electron donor and carbon source after aerobic pretreatment, enhanced the abundance of microbial taxa belonging to Firmicutes and Aeromonas , known for their involvement in electron transfer and reduction processes related to ClO 4 -. This study highlighted the potential of aerobic pretreatment of food waste combined with anaerobic fermentation to produce FBFW and enhance ClO 4 - reduction, offering new perspectives for food waste utilization and the remediation of high ClO 4 - contamination. [Display omitted] • Aerobic pretreatment increased lactate content and decreased NH 4 +-N concentration. • FBFW exhibited a higher ClO 4 - removal rate compared to acetate. • Firmicutes and Aeromonas are beneficial for ClO 4 - reduction. [ABSTRACT FROM AUTHOR]

The subterranean estuary (STE) is a recognized reactive biogeochemical zone at the groundwater–seawater interface in coastal regions. However, few studies have explored dissolved organic matter (DOM) and nutrient processes in buried organic-rich STEs (with up to 20 % of organic matter content), despite their potential contributions to coastal water hypoxia and greenhouse gas emissions. This study conducted controlled laboratory experiments to investigate the physicochemical controls on DOM and nutrient processing in organic-rich STEs, considering variations in groundwater nitrate (NO 3 –) concentrations, salt concentration, seawater ions, and incubation times. Results showed elevated levels of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in pore water, primarily from particulate organic matter (POM) degradation that originated from decayed vascular plants. POM-to-DOM degradations further resulted in the accumulation of ammonium (NH 4 +) and highly unsaturated compounds in all treatments. The addition of high-ionic-strength treatments (e.g., seawater and sodium chloride [NaCl] solution) reduced DOC solubility and selectively removed dissolved aromatic compounds in porewater. The cation-rich seawater shifted the porewater NH 4 + generation pathway from predominantly biological (re)mineralization in freshwater to abiotic (desorption via ion exchange) pathways in the saline water setup. Orthophosphate (PO 4 3−) dynamics were likely to be influenced by the iron-rich sediment surface in both freshwater and saline water scenarios. Our experiments further indicated that the long-term incubation enriched DOM concentration with a high degradation state. This work demonstrated that organic-rich STEs are significant sources of less labile DOM and NH 4 + to coastal waters. In the context of global climate change, our results illustrate the sensitivity of DOM and nutrient biogeochemical cycling in STEs to salinization and altered residence time, consequently affecting the quantity and quality of DOM and nutrients transported to coastal waters. [ABSTRACT FROM AUTHOR]

Nucleic acid-based therapies have become a game-changing player in our way of conceiving pharmacology. Nevertheless, the inherent lability of the phosphodiester bond of the genetic material with respect to the blood nucleases severely hampers its delivery in naked form, therefore making it necessary to use delivery vectors. Among the potential non-viral vectors, polymeric materials such as the poly(β-aminoesters) (PBAEs) stand out as promising gene carriers thanks to their ability to condense nucleic acids in the form of nanometric polyplexes. To keep advancing these systems into their translational preclinical phases, it would be highly valuable to gain accurate insights of their in vivo pharmacokinetic profile. We envisaged that positron emission tomography (PET)-guided imaging could provide us with both, an accurate assessment of the biodistribution of PBAE-derived polyplexes, as well shed light on their clearance process. In this sense, taking advantage of the efficient [19F]-to-[18F]‑fluorine isotopic exchange presented by the ammonium trifluoroborate (AMBF 3) group, we have designed and synthesized a new 18F-PET radiotracer based on the chemical modification of a linear poly(β-aminoester). As proof of concept, the incorporation of the newly developed 18F-PBAE into a model nanoformulation was shown to be fully compatible with the formation of the polyplexes, their biophysical characterization, and all their in vitro and in vivo functional features. With this tool in hand, we were able to readily obtain key clues about the pharmacokinetic behavior of a series of oligopeptide-modified PBAEs (OM-PBAEs). The observations described in this study allow us to continue supporting these polymers as an outstanding non-viral gene delivery vector for future applications. [Display omitted] • A new 18F-PET radiotracer based on linear poly(β-aminoester) have been developed. • PET biodistribution studies using the novel PBAE-radiotracer showed a rapid excretion of the vector. • Pharmacokinetic information highlights the promising potential of this type of gene carriers. [ABSTRACT FROM AUTHOR]

Microalgae is a potential source of bioproducts, including feedstock to biofuels. Urea has been pointed as potential N source for microalgae growth. Considering that urea metabolism releases HCO 3 - to the medium, we tested the hypothesis that this carbon source could improve photosynthesis and consequently growth rates of Chlamydomonas reinhardtii. In this sense, the metabolic responses of C. reinhardtii grown with ammonium and urea as nitrogen sources under mixotrophic and autotrophic conditions were investigated. Overall, the mixotrophy led to increased cell growth as well as to a higher accumulation of lipids independent of N source, followed by a decrease in photosynthesis over the growth phases. In mixotrophy, urea stimulates growth in terms of cell number and dry weight. Furthermore, higher photosynthesis was verified in late logarithmic phase compared to ammonium. Under autotrophy conditions, although cell number and biomass were reduced, there was higher production of starch independent of N source. Nonetheless, urea-based autotrophic treatments stimulated biomass production compared to ammonium-based treatment. Under mixotrophy higher input of carbon into the cell from acetate and urea optimized photosynthesis and consequently promoted cell growth. Together, these results suggest urea as alternative source of carbon, improving photosynthesis and cell growth in C. reinhardtii. [Display omitted] • Bicarbonate from urea metabolism improve microalgal growth. • Mixotrophy increase lipid production in Chlamydomonas reinhardtii. • Urea stimulates photosynthesis and biomass production in Chlamydomonas reinhardtii. [ABSTRACT FROM AUTHOR]

To investigate the impact of emission controls on ammonia (NH 3) pollution in urban atmosphere, observation on NH 3 (1 hr interval) was performed in Shanghai before, during and after the 2019 China International Import Expo (CIIE) event, along with measurements on inorganic ions, organic tracers and stable nitrogen isotope compositions of ammonium in PM 2.5. NH 3 during the CIIE period was 6.5±1.0 µg/m3, which is 41% and 32% lower than that before and after the event, respectively. Such a decrease was largely ascribed to the emission controls in nonagricultural sources, of which contribution for measured NH 3 in control phase abated by ∼20% compared to that during uncontrol period. Molecular compositions of PAHs and hopanes further suggested a dominant role of the reduced vehicle emissions in the urban NH 3 abatement during the CIIE period. Our results revealed that vehicle exhaust emission control is an effective way to mitigate NH 3 pollution and improve air quality in Chinese urban areas. [Display omitted] [ABSTRACT FROM AUTHOR]

• Comammox bacteria were enriched in the mainstream PN/A reactor. • AOMs showed kinetic advantages over anammox bacteria at residual ammonium <5 mg/L. • The in situ anammox activity decreased remarkably due to low ammonium availability. • The loss of anammox activity triggered the NOB activation and PN/A deterioration. Residual ammonium is a critical parameter affecting the stability of mainstream partial nitritation/anammox (PN/A), but the underlying mechanism remains unclear. In this study, mainstream PN/A was established and operated with progressively decreasing residual ammonium. PN/A deteriorated as the residual ammonium decreased to below 5 mg/L, and this was paralleled by a significant loss in anammox activity in situ and an increasing nitrite oxidation rate. Further analysis revealed that the low-ammonium condition directly decreased anammox activity in situ via two distinct mechanisms. First, anammox bacteria were located in the inner layer of the granular sludge, and thus were disadvantageous when competing for ammonium with ammonium-oxidizing bacteria (AOB) in the outer layer. Second, the complete ammonia oxidizer (comammox) was enriched at low residual ammonium concentrations because of its high ammonium affinity. Both AOB and comammox presented kinetic advantages over anammox bacteria. At high residual ammonium concentrations, nitrite-oxidizing bacteria (NOB) were effectively suppressed, even when their maximum activity was high due to competition for nitrite with anammox bacteria. At low residual ammonium concentrations, the decrease in anammox activity in situ led to an increase in nitrite availability for nitrite oxidation, facilitating the activation of NOB despite the dissolved oxygen limitation (0.15–0.35 mg/L) for NOB persisting throughout the operation. Therefore, the deterioration of mainstream PN/A at low residual ammonium was primarily triggered by a decline in anammox activity in situ. This study provides novel insights into the optimized design of mainstream PN/As in engineering applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Ammonia nitrogen (NH 4 +-N) is a ubiquitous environmental pollutant, especially in offshore aquaculture systems. Electrochemical oxidation is very promising to remove NH 4 +-N, but suffers from the use of precious metals anodes. In this work, a robust and cheap electrocatalyst, iron single-atoms distributed in nitrogen-doped carbon (Fe-SAs/N-C), was developed for electrochemical removal of NH 4 +-N from in wastewater containing chloride. The Fe-SAs/N-C catalyst exhibited superior activity than that of iron nanoparticles loaded carbon (Fe-NPs/N-C), unmodified carbon and conventional Ti/IrO 2 -TiO 2 -RuO 2 electrodes. And high removal efficiency (> 99%) could be achieved as well as high N 2 selectivity (99.5%) at low current density. Further experiments and density functional theory (DFT) calculations demonstrated the indispensable role of single-atom iron in the promoted generation of chloride derived species for efficient removal of NH 4 +-N. This study provides promising inexpensive catalysts for NH 4 +-N removal in aquaculture wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

• AMX granulation profile differs significantly in different enrichment conditions • Activity of Na+/K+-ATPase causes granule porosity and reduces floatation ability • Favourable enrichment condition leads to improved ABR for the S_AMX granules • EPS content amplifies the disparity between granulation and saline stress survival The growing interest in the anaerobic ammonium oxidizing (AMX) process in treating high nitrogen containing wastewaters and a comprehensive study into the granulation mechanism of these bacteria under diverse environmental conditions over the years have been unequal. To this effect, the distinctive differences in saline adapted AMX (S_AMX) and non-saline adapted AMX (NS_AMX) granules are presented in this study. It was observed that substrate utilisation profiles, granule formation mechanism, and pace towards granulation differed marginally for the two adaptation conditions. The different microbial dominant aggregation types aided in splitting the 471 days operated lab-scale SBRs into three distinct phases. In both reactors, phase III (granules dominant phase) showed the highest average nitrogen removal efficiency of 87.9% ± 4.8% and 85.6% ± 3.6% for the S_AMX and NS_AMX processes, respectively. The extracellular polymeric substances (EPS) quantity and major composition determined its role either as a binding agent in granulation or a survival mechanism in saline adaptation. It was also observed that granules of the S_AMX reactor were mostly loosely and less condensed aggregates of smaller sub-units and flocs while those of the NS_AMX reactor were compact agglomerates. The ionic gradient in saline enrichment led to an increased activity of the Na+/K+ – ATPase, hence enriched granules produced higher cellular adenosine triphosphate molecules which finally improved the granules active biomass ratio by 32.96%. Microbial community showed that about three to four major known AMX species made up the granules consortia in both reactors. Proteins and expression of functional genes differed for these different species. [Display omitted] [ABSTRACT FROM AUTHOR]

We investigated variations of PM 2.5 and water-soluble inorganic ions chemical characteristics at nine urban and rural sites in China using ground-based observations. From 2015 to 2019, mean PM 2.5 concentration across all sites decreased by 41.9 µg/m3 with a decline of 46% at urban sites and 28% at rural sites, where secondary inorganic aerosol (SIAs) contributed to 21% (urban sites) and 17% (rural sites) of the decreased PM 2.5. SIAs concentrations underwent a decline at urban locations, while sulfate (SO 4 2–), nitrate (NO 3 –), and ammonium (NH 4 +) decreased by 49.5%, 31.3% and 31.6%, respectively. However, only SO 4 2– decreased at rural sites, NO 3 – increased by 21% and NH 4 + decreased slightly. Those changes contributed to an overall SIAs increase in 2019. Higher molar ratios of NO 3 – to SO 4 2– and NH 4 + to SO 4 2– were observed at urban sites than rural sites, being highest in the heavily polluted days. Mean molar ratios of NH 3 /NH x were higher in 2019 than 2015 at both urban and rural sites, implying increasing NH x remained as free NH 3. Our observations indicated a slower transition from sulfate-driven to nitrate-driven aerosol pollution and less efficient control of NO x than SO 2 related aerosol formation in rural regions than urban regions. Moreover, the common factor at urban and rural sites appears to be a combination of lower SO 4 2– levels and an increasing fraction of NO 3 – to PM 2.5 under NH 4 +-rich conditions. Our findings imply that synchronous reduction in NO x and NH 3 emissions especially rural areas would be effective to mitigate NO 3 –-driven aerosol pollution. [Display omitted] [ABSTRACT FROM AUTHOR]

Ammonium promotes rice P uptake and reutilization better than nitrate, under P starvation conditions; however, the underlying mechanism remains unclear. In this study, ammonium treatment significantly increased putrescine and ethylene content in rice roots under P deficient conditions, by increasing the protein content of ornithine decarboxylase and 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase compared with nitrate treatment. Ammonium treatment increased rice root cell wall P release by increasing pectin content and pectin methyl esterase (PME) activity, increased rice shoot cell membrane P release by decreasing phosphorus-containing lipid components, and maintained internal P homeostasis by increasing OsPT2/6/8 expression compared with nitrate treatment. Ammonium also improved external P uptake by regulating root morphology and increased rice grain yield by increasing the panicle number compared with nitrate treatment. The application of putrescine and ethylene synthesis precursor ACC further improved the above process. Our results demonstrate for the first time that ammonium increases rice P acquisition, reutilization, and homeostasis, and rice grain yield, in a putrescine- and ethylene-dependent manner, better than nitrate, under P starvation conditions. • Ammonium increased cell wall P reutilize in rice compared with nitrate. • Ammonium increased cell membrane P reutilize in rice compared with nitrate. • Ammonium increased P uptake via modifying root architecture compared with nitrate. • Ammonium increased the synthesis of putrescine and ethylene compared with nitrate. Ammonium increased rice P uptake and reutilization via increasing ethylene and putrescine content and improved rice grain yield. [ABSTRACT FROM AUTHOR]

In this study, ammonium was removed from an aqueous solution by using the Emulsion Liquid Membrane technique. The optimum values of the parameters that had effects on the removal process were determined and results were analyzed using statistical methods. As a result of the conducted experiments, it was determined that the volumetric ratio of the emulsion phase was 0.12, the effective internal phase source was H 2 SO 4, the internal phase volumetric ratio was 0.42, the internal phase concentration was 0.36 N, the surfactant ratio was 2 %, the diluent ratio was 34/64 (mineral oil/toluene, %, v/v), homogenizer speed and time were 10,000 rpm and 1 min, agitation speed was 250 rpm, and external phase pH was 10.80. The fact that 98 % yield was achieved in a very short extraction time (15 s) under optimal conditions and the fact that the studies conducted on this subject in the literature are limited and different reveals the importance of this study obviously. [Display omitted] [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation represents an important pathway of N loss, which can be coupled with reduction of nitrite and metal(loid)s (e.g., Fe(III) and Mn(IV)). Similar to Fe(III) and Mn(IV), As(V) is also an active metal(loid) and ammonium oxidation coupled with As(V) reduction is thermodynamically feasible. However, little is known about this potential process. In this study, anaerobic ammonium oxidation coupled with As(V) reduction, designated as Asammox, was observed in cultures inoculated from As-contaminated paddy soil using 15N isotope tracer analysis. Compared with the treatment amended with 15N-urea only, the production of 15N-labeled N 2 (i.e., 30N 2 and 29N 2) was significantly greater in the treatment amended with As(V) and 15N-urea. Furthermore, the abundances of the genes encoding for arsenate reductase (arrA) and hydrazine synthase (hzsB) were significantly higher in the treatment amended with As(V) and 15N-urea than those in the treatment amended with 15N-urea only. In addition, putative Asammox bacteria affiliated with Halomonas , Pelagibacterium, and Chelativorans were identified by DNA-stable isotope probing. Members of Ca. Brocadia were the most dominant Anammox bacteria in the soil cultures and may interact with Asammox bacteria in ammonium oxidation, suggesting that the N loss may be attributed to the contribution of Asammox and Anammox in the As-contaminated soil. The observation of Asammox, a novel biogeochemical process, and identification of bacteria responsible for this biogeochemical process expands the fundamental understanding of both N and As biogeochemical cycling. In addition, this study provides a proof-of-concept for investigating anaerobic ammonium oxidation coupled with metal(loid)s reduction by combining stable isotope probing and isotope tracer microcosm incubations. [ABSTRACT FROM AUTHOR]

• Ammonium fluorosilicate was studied under high pressure by Synchrotron X-ray diffraction. • Ammonium fluorosilicate was studied under high pressure by Raman Spectroscopy. • The phase transition mechanism of ammonium fluorosilicate is indicated. • A large modification in the material's compressibility was observed at 0.3 GPa. The ammonium fluorosilicate has been investigated by Synchrotron powder X-ray diffraction (XRD) and Raman spectroscopy experiments with diamond anvil cells (DAC) up to 20 GPa at room temperature. The experimental results show that a phase transition from the cubic phase (Fm 3 ¯ m) to the trigonal phase (P 3 ¯ m1) occurs at 0.3 GPa with a volume collapse of ∼6.3 %. The phase transition mechanism is related to the change in the ordering of hydrogen atoms of ammonium fluosilicate. The pressure-volume data of ammonium fluosilicate are fitted to the second-order Birch-Murnaghan equation of state, yielding V 0 = 592.7(15) A3 and K 0 = 12.2(9) GPa for the cubic phase and V 0 = 134.5(2) A3, K 0 = 53.8(11) GPa for the trigonal phase. The axial compression ratio of trigonal ammonium fluosilicate, α(c)/α(a), is approximately 1.36, indicating anisotropy. The high-pressure phase of ammonium fluorosilicate exhibits improved compression properties and catalytic activity, suggesting its potential for industrial applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The significance of examining groundwater quality is highlighted by the fact that 75% of the European Union population relies on groundwater for their water supply. In the Republic of Serbia, over 50% of the groundwater used for public water supply comes from alluvial aquifers, with 80–90% of this water originating from river water infiltration. This study investigates the origin of increased ammonium concentrations (up to 4.7 mgN/l) in the Danube alluvial aquifer near Kovin-Dubovac area, Serbia, a potential future regional water supply source surrounded by intensive agricultural production and an open coal mine. Comprehensive research involved statistical processing of physicochemical data (13 parameters from 33 sampling sites), isotopic analyses (δ15N–NH 4 – 12 samples; δ34S–SO 4 , δ18O–SO 4 in 5 samples), and microbiological tests (denitrifying, sulphate-reducing, iron-related, and heterotrophic aerobic bacteria in 15 samples). Factor analysis revealed significant positive loadings (>0.5) among indicators of autochthonous organic matter origin (Fe2+, Fe tot , and TOC), geological matrix components (Na, H 2 S, Cl), and groundwater state parameters (pH, Eh, and NH 4 +). This multifaceted approach and the spatial concentration gradients of parameters associated within extracted principal components revealed the predominance of two NH 4 + sources. The riparian zone is characterized by sediment organic matter mineralization, increased iron content, and natural ammonium origin (δ15N–NH 4 + from +4.82‰ to +6.93‰) accompanied by conditions suitable for DNRA and sulphate reduction. Approaching to the hinterland lower iron and total organic matter content, accompanied by increased redox values revealed the signature of fertilizers application (δ15N–NH 4 + −0.84‰ and −0.33‰), associated with denitrification influence. This multifaceted approach reduces ambiguity, providing a clearer interpretation of results when discerning the origin of nitrogen and aquifer potential for nitrogen loss or conservation in a reducing groundwater environment. • The anoxic alluvial groundwater was investigated. • Hydrogeochemical, microbiological and isotopic data analysis was conducted. • The signatures of different N transformations and N origin are revealed. • The interaction of N and S cycles in anoxic groundwater was investigated. [ABSTRACT FROM AUTHOR]

APS is a cheap and eco-friendly oxidant which enables one-step extraction of nanochitin (NCh) from fishery wastes. However, it is challenging to improve the preparation efficiency and NCh quality simultaneously, owing to the uneven or uncontrollable oxidation. Herein, we propose a simple and controllable way to isolate chitin nanofibers (ChNFs) from squid pen by gradient heating activated (GHA)- ammonium persulfate (APS) oxidation. Compared to the isothermal activated (ITA)-APS oxidation, our strategy reduced the mass ratio of squid pen to APS from 1:45 to 1:6 and reaction time from 15 h to 8 h. Meanwhile, the as-prepared ChNFs exhibited high yield (91.5 %), light transmittance (98 % at 500 nm), crystallinity index (96.9 %), and carboxyl content (1.53 mmol/g). GHA-APS oxidation involved multiple continuous heating and isothermal stages. The former stimulates a moderate activation of APS and enhances the oxidation rate, while the latter provides a duration for surface chemistry. This non-isothermal heating facilitates the continuous decomposition of APS at a relatively high and consistent rate, thereby enhances its oxidation efficiency. Furthermore, green assessments indicate this method is simple, time-saving, eco-friendly and cost-effective. Overall, this work introduces a novel perspective for the industrial extraction of high-efficiency and high-quality nanomaterials. [Display omitted] [ABSTRACT FROM AUTHOR]

In diagenetic solutions, ammonium may be incorporated into smectites as an exchangeable cation and become fixed within the interlayer space of illites and other white micas. To study the potential impact of NH 4 + on the smectite-to-illite transformation reaction, a series of hydrothermal experiments were carried out at 100, 150 and 200 °C, spanning reaction duration from 15 to 90 days, and two NH 4 + concentrations (0.1 and 0.2 M). The solids resulting from these alteration experiments were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and transmission and analytical electron microscopy (TEM and AEM). The XRD analysis revealed that, under the specified experimental conditions, smectite incorporates NH 4 + in the structure, leading to the formation of non-swelling layers, resulting in partial transformation to illite layers and producing packets of disordered illite/smectite (I/S). In addition, a minor XRD peak at ∼10 Å suggests the formation of discrete illite crystals. The FTIR spectra demonstrated the uptake of NH 4 +, with deformation bands observed at 1400 and 1430 cm−1, corresponding to exchangeable NH 4 + in smectite and fixed NH 4 + in high-charge layers, respectively. TEM analysis revealed that smectite particles exhibited wavy stacks comprising a few layers with abundant defects and lateral discontinuities. The interlayer spacing in these particles ranged from 12 to 15 Å and became thinner and more plate-like with increasing temperature and time. Moreover, they contained inclusions of 10–10.3 Å layers, either as discrete layers or in packets of several layers, indicating the formation of disordered mixed-layer illite-smectite. Lateral transitions from 12 to 15 Å to 10 Å layers were frequently observed and interpreted as reaction fronts due to local rearrangement. At 150 and 200 °C, isolated packets of 10 Å layers were identified as discrete illite crystals that precipitated directly from solution. Analysis of the chemical composition of individual particles revealed an increase in octahedral charge (MgVI for AlVI substitution) in smectite particles, followed by increase in tetrahedral charge in I/S particles. Interlayer NH 4 + played a stabilizing role in the high-charge layers and favored the smectite-to-illite conversion process. • Smectite transforms into illite under alkaline (NH 4 +) hydrothermal solutions by NH 4 + adsorption at the interlayer spaces. • Dissolution and NH 4 + fixation convert smectite to illite, increasing AlIV and MgVI, and forming disordered I/S structures. • The process is further enhanced with higher temperature, prolonged reaction times, and increased NH 4 + concentration. [ABSTRACT FROM AUTHOR]

• A new modification of RbVOPO 4 has been synthesized for the first time through mild ion exchange using NH 4 VOPO 4 as a precursor. • The crystal structure of the RbVOPO 4 was refined using the Rietveld method. The model has been verified by selected area electron diffraction (SAED), high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and infrared spectroscopy. • BVSE and DFT calculations have been performed: the RbVOPO 4 is featured by a one-dimensional diffusion network (E a = 0.2 eV). • Electrochemical measurements results are in agreement with theoretical findings: KTiOPO 4 -structured RbVOPO 4 demonstrates reversible cycling of alkali metal cations. In this paper, we report on a new polymorph of rubidium vanadium oxophosphate (α-RbVOPO 4) adopting a KTiOPO 4 -type structure, which was stabilized through an ion-exchange reaction between a hydrothermally prepared NH 4 VOPO 4 precursor and Rb 2 CO 3 ·1.5H 2 O. The crystal structure of α-RbVOPO 4 was refined based on X-ray powder diffraction data and verified by infrared spectroscopy, selected area electron diffraction, and high-resolution scanning transmission electron microscopy. The material was examined as a host for reversible (de)insertion of Rb+ ions using bond valence force field and density functional theory calculations disclosing a one-dimensional diffusion network with an activation barrier of ∼0.2 eV. The electrochemical activity of RbVOPO 4 was studied experimentally in two-electrode cells with Li, Na, and K metal counter electrodes. Electronic structure calculations confirmed vanadium redox during Rb+ (de)insertion. The α-RbVOPO 4 phase was compared with the known RbVOPO 4 polymorphic modification, β-RbVOPO 4 , demonstrating no ionic mobility. The crystal chemistry of all known compounds in the Rb-V-P-O system is reviewed. This work supplements the existing toolkit on synthesizing the KTiOPO 4 -structured electrode materials for metal-ion batteries and discusses their crystal structure features. [Display omitted] [ABSTRACT FROM AUTHOR]

Globally, approximately 50% of nitrogen (N) fertilizer applied in agricultural practices escapes into the environment, resulting in water and air pollution and ozone depletion. Soil N transformation processes determine the chemical form of N and the amount of the various N forms, controlling where N fertilizer goes and how much of it is lost. Therefore, a comprehensive understanding of soil N transformation responses to N fertilizer is critical for developing effective management strategies to improve soil N retention capacity and minimize soil N losses. Using 15N tracing techniques with acetylene inhibition, three ranges for ammonium concentration in fertilizer were identified (I: 14–16, II: 46–59, and III: 90–115 mg N kg−1, depending on type of organic materials added) that determine competition for mineral N among N transformation processes under increased carbon availability in an agricultural soil. Increasing ammonium concentration caused a shift from a nitrate assimilation-dominated (III) period in organic amendment addition treatments. Structural equation modeling revealed that ammonium addition inhibited soil nitrate assimilation by enhancing nitrification and ammonium assimilation, resulting in the shift. Consequently, the ratios of nitrification to ammonium assimilation and to gross N assimilation (nitrate assimilation + ammonium assimilation) increased significantly in response to elevated ammonium concentration with organic amendment addition, indicating lower N retention capacity and higher potential risks of N loss. Overall, we present a comprehensive picture of how concurrent gross N transformation processes interact to compete for mineral N in response to ammonium-forming fertilizer application, and demonstrate that nitrification and ammonium assimilation weaken the stimulating effect of organic amendment on nitrate assimilation with increasing ammonium concentration. • Levels of ammonium addition caused a shift of dominant N conversion process. • Ammonium addition inhibited soil nitrate assimilation rate by enhancing gross nitrification and ammonium assimilation rates. • Elevated ammonium content increased the ratios of nitrification to ammonium assimilation and to gross N assimilation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Inhalation of (NH 4) 2 SO 4 and NH 4 NO 3 induces damage in various tissues, including intestine. • Ammonium mixture damages the intestine structure, and silibinin treatment conserves the intestinal structure. • Silibinin treatment effectively mitigates inflammation and oxidative stress in the intestine. • Silibinin reduced excessive autophagy via the PI3K/AKT signaling pathway. Industrialization and urbanization produce hazardous particulate matter (PM), including ammonium compounds like (NH 4) 2 SO 4 and NH 4 NO 3 , which comprise around 50 % of PM. Despite this, the influence of ammonium on intestinal inflammation remains unclear. We studied an ammonium mixture's effects on the intestine, finding elevated pro-inflammatory cytokines and oxidative stress in exposed mice, causing small intestine morphological changes. Investigating mitigation strategies, we assessed silibinin, an antioxidant from milk thistle seeds. Silibinin treatment in (NH 4) 2 SO 4 - and NH 4 NO 3 -exposed mice significantly reduced inflammatory markers, alleviated oxidative stress, and preserved intestinal tissue integrity via the PI3K/AKT pathway. Our findings elucidate ammonium's potential impact on intestinal inflammation and highlight silibinin's therapeutic impact against PM-induced small intestine damage. [ABSTRACT FROM AUTHOR]

• The EPWs of quaternary ammonium salts-based DESs were determined. • The chemical structure and interaction energy of all DESs were calculated and optimized. • The interaction between HBD and HBA was analyzed utilizing the COSM-RS theoretical model. To gain a deeper understanding of the formation mechanism for quaternary ammonium salts-based deep eutectic solvents (DESs), it is of great significance to investigate the interaction between hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA), as well as their physicochemical properties. In this study, tetrapropylammonium bromide (TPAB) or tetrabutylammonium bromide (TBAB) as HBA and malonic acid (MA) as HBD with a molar ratio of 1:1 or 1:1.5 were to synthesize four DESs of [TPAB]:[MA]-1, [TPAB]:[MA]-1.5, [TBAB]:[MA]-1 and [TBAB]:[MA]-1.5. The thermodynamic properties, electrochemical properties, and interaction behaviors of these DESs were investigated. The thermodynamic parameters of the standard entropy, lattice energy, molar refraction, molar polarization, and molar electrical conductivity for all DESs were calculated in terms of the Glasser's classical theory, the molar surface Gibbs energy definition, the molar electrical conductivity definition, and Lorentz-Lorenz equation. Through linear scanning curve tests based on the three-electrode method, electrochemical potential windows (EPW) of all DESs were significantly higher than 2 V. Furthermore, according to DFT calculation and COSMO-RS theoretical model, the sequence of interaction strength for quaternary ammonium salts-based DESs was arranged as follows: [TBAB]:[MA]-1 > [TPAB]:[MA]-1 > [TBAB]:[MA]-1.5 > [TPAB]:[MA]-1.5. These fundamental theoretical studies help to provide significant theoretical reference value for the design of DESs with special properties, and promote the application range of DESs. [ABSTRACT FROM AUTHOR]

Urea is a biomarker for diagnosis and management of multiple disorders. The measurement of urea could help in the diagnosis of patients with kidney dysfunction. Despite their attractive analytical performances, the existing urea measurement methods are still limited to sophisticated and time–consuming or require invasive blood sampling. Herein, a reliable noninvasive, simple, and disposable touch–based potentiometric sensor is fabricated for rapid monitoring of fingertip sweat urea. Novel touch–based urea detection relies on immobilized urease recognition and a solid–contact ammonium–ion–selective electrode, along with a screen–printed carbon working electrode modified carboxylated carbon nanotubes for enhancing sensor's sensitivity. The fingertip sweat under sedentary rest conditions can be instantaneously collected on customized porous polyvinyl alcohol hydrogel transporting sweat to working electrode surface where the hydrolysis of urea is catalyzed, generating bicarbonate and ammonium. The resulting ammonium can be detected with ion–selective transducer, enabling indirect monitoring of sweat urea. Potential interference from co–existing ammonium in human sweat is addressed by developing a dual disposable potentiometric sensor, consisting of urea and ammonium sensors on a single strip platform allowing for simultaneous touch–based detection of sweat urea and ammonium. The resulting dual disposable sensing system offers rapid urea and ammonium monitoring within a group of healthy human subjects, along with a good correlation with R2 = 0.974 between the sweat urea and capillary blood urea levels. Additional confirmation among a broad sample of individuals along with the validation of sensor data through centralized laboratory tests will establish the practicality of simultaneously monitoring urea and ammonium levels. [Display omitted] • Dual sensor detects urea and ammonium in fingertip sweat simultaneously. • Rapid monitoring with good correlation to blood urea. • Potential for point–of–care and self-testing in medical diagnosis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultra-high nitrogen removal efficiency (NRE) of 95.5% at C/N of 2.7 was achieved. • Lower NAR (range 40 %∼70 %) instead resulted in better anammox contribution and NRE. • High-efficiency EPDA with less NO X - loss dominated in ammonium removal than PN/A. • Enriching NOB and GAOs in PN/A process instead favored co-metabolism stability. • The nitrate introduction effectively attenuated the competition of ED for nitrite. Higher nitrite accumulation, which is challenging to achieve reliably, is always sought to obtain better nitrogen removal performance in traditional partial nitritation-anammox (PN/A) process. This study developed a modified PN/A process by introducing nitrite-oxidizing bacteria and endogenous metabolism. Advanced nitrogen removal performance of 95.5 % was achieved at a low C/N ratio of 2.7 under nitrite accumulation ratio (NAR) fluctuations. Higher nitrate accumulation at lower NAR (70 ∼ 40 %) resulted in superior anammox contribution (60 ∼ 75 %) and nitrogen removal performance (93 ∼ 98 %). This was attributed to the higher nitrogen removal efficiency of the post-anoxic endogenous partial denitrification coupling anammox process, although the PN/A process occurring first possessed a faster anammox rate of 2.0 mg NH 4 +-N /(g VSS⋅h). The introduction of nitrate allowed more nitrite flow to anammox, promoting a high enrichment of anammox bacteria (Ca. Brocadia, 0.3 % to 2.8 %). This study provides new insights into the practical application of the PN/A process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The study focuses on solutes in the GI aqueous extract of compost products. • Acetic acid, formic acid and NH 4 + are inhibitory factors influencing GI. • The inhibitory concentration of acetic acid corresponding to 70 % GI is 85 mg/L. • The inhibitory concentrations of formic acid and NH 4 + are 85 and 104 mg/L. • Cl− have no inhibitory effect on GI; instead, they exhibit a promoting effect. The seed germination index (GI) serves as the principal determinant that impedes the integration of aerobic composting products into agricultural lands. The current research work predominantly focuses on exploring the correlation between physical and chemical indicators of the compost products and GI, neglecting the fundamental cause. This study systematically analyzed the composition of GI aqueous extracts from compost products derived from kitchen waste under various composting methodologies, with nitrogen, carbon, and inorganic salt as critical factors. The analytical work concluded that acetic acid, formic acid, and ammonium were the inhibitory factors influencing GI. Validation experiments introduced inhibitory factors, yielding a functional relationship formula depicting GI variations due to a single influential factor. This study conclusively identified acetic acid as the primary constraint, establishing that its inhibitory concentration corresponded to 70 % GI stands at 85 mg/L. This study will provide guidelines for the future research on enhancing aerobic composting techniques. [ABSTRACT FROM AUTHOR]

• There is a need for foliar application of boron and molybdenum on navel orange trees under Egyptian conditions due to the alkaline pH of its soil. • Treating navel orange trees with boron and molybdenum improved the productivity and fruit quality. • Foliar application by a combination of 4 % boric acid and 6 % ammonium molybdate improved productivity and fruit quality of navel orange. The majority of Egyptian soil has an alkaline pH of up to 8. As a result, plants have trouble absorbing certain nutrients, and it is necessary to add them via another method. Thus, the current study's objective was to find the ideal combination of molybdenum and boron to produce the highest possible levels of both quantitative and qualitative fruit yield. Molybdenum (ammonium molybdate) concentrations of 2 %, 4 %, and 6 %, were combined with boron in the form of boric acid, with 2 % and 4 %, concentrations of treated foliar applied to navel orange trees. In comparison to the control treatment, which involved spraying the trees with clean water, and other treatments, the results of the study during the two seasons indicated that treating the trees with 6 % ammonium molybdate and 4 % boric acid (T7) resulted in the highest statistical increases in shoot length, canopy volume, leaf intensity of staining green, leaf area, and leaf content of necessary mineral elements. Additionally, the same treatment resulted in a better fruit set and decreased fruit loss, which raised the yield factor as well as the number and weight of fruits produced by each tree. Furthermore, the impact also included enhancing the crop's quality (fruit weight and size), yield efficiency, vitamin C and SSC content, acidity reduction, and improved fruit peel color quality through an increase in carotene and chlorophyll A. In comparison to the control and other treatments, T7 also led to a decrease in the fruits' nitrate and nitrite content. In the current investigation, ammonium molybdate and boric acid were combined with boron in the form of boric acid were enhanced productivity and fruit quality of Navel orange. [ABSTRACT FROM AUTHOR]

Geogenic arsenic (As) and ammonium (NH 4 +)-contaminated groundwaters are global public concerns, posing threats to human health and ecological security. However, when considering the enrichment of either As or NH 4 + in groundwater, the concurrent occurrence of both contaminants warrants further discussion. Herein, we conducted a hydrogeochemical study in the shallow confined aquifer of the central Yangtze River basin to elucidate the key mechanism of coexistence of As and NH 4 + through a thorough analysis of groundwater chemistry, inorganic carbon isotope (δ 13C-DIC), and dissolved organic matter (DOM). High As and NH 4 + groundwater mainly occurs in meanders of the middle reaches of Yangtze River, with maximum concentrations up to 936 μg/L and 45.3 mg/L, respectively. Our findings indicate that the degradation levels and characteristics of DOM play a significant role in the co-occurrence of As and NH 4 + with varying concentrations in groundwater. δ 13C-DIC signatures show that there was a simultaneous increase in the concentrations of As and NH 4 + in groundwater, with the highest concentration of As during fermentative conditions. In contrast, during the progression of OM degradation towards methanogenesis, the NH 4 + concentration reached its peak, while the As concentration was lower compared to the fermentation stage. Optical properties of DOM demonstrate that elevated levels of NH 4 + result from the mineralization of N-containing organic compounds particularly as the degradation proceeds to methanogenesis stage, while both fermentation and methanogenesis processes significantly contribute to the microbially reductive dissolution of As-bearing iron oxides in groundwater systems. This study presents isotopic and fluorescent evidence to clarify the co-existence of As and NH 4 + in Quaternary alluvial-lacustrine aquifers. [Display omitted] • Co-occurrence and distribution of arsenic and ammonium in groundwater are observed. • Degradation levels and characteristics of DOM affect the co-occurrence of As and NH 4 +. • NH 4 + enrichment is the result of mineralization of nitrogenous OM at methanogenesis stage. • As Release and enrichment are promoted at both fermentative and methanogenic processes. [ABSTRACT FROM AUTHOR]

The multifunctional cotton fabrics, which were expected to become one of the most promising textile materials, gained much attention in the apparel market. In this work, the simultaneous coloration and finishing processes with natural dye were carried out to prepare the multifunctional cotton fabrics. The modification process using ammonium polyphosphate (APP) imparted the cotton fabric with numerous anionic sites along with flame retardant and anti-wrinkle properties. Subsequently, the implementation of coloration with berberine was to render the cotton fabric with elegant shade and anti-bacterial, ultraviolet (UV) protection performances. The obtained results revealed that the cotton fabric treated with APP could obtain deep shade. It was found that the limited oxygen index (LOI), wrinkle recovery angle (WRA), ultraviolet protection factor (UPF) and antibacterial efficiency of treated fabric were 46.4%, 252°, 193 and 99%, respectively. More importantly, the repeated laundering showed negligible influence on the flame retardant and anti-wrinkle performances. In addition, the anti-bacterial and UV protection performance of treated cotton fabric exhibited a slight decline even after 20 cycles of washing. Finally, the washing and rubbing fastness of obtained cotton fabric were also desirable. [Display omitted] • The synergistic effect of APP and berberine imparted cotton multi-function. • The anionic treatment of cotton using APP significantly enhanced dye exhaustion. • Application of APP endowed cotton with flame retardant and anti-wrinkle properties. • UV protection and anti-bacterial properties of cotton was improved using berberine. [ABSTRACT FROM AUTHOR]

Cytokinins are growth-regulating plant hormones that are considered to adjust plant development under environmental stresses. During sole ammonium nutrition, a condition known to induce growth retardation of plants, altered cytokinin content can contribute to the characteristic ammonium toxicity syndrome. To understand the metabolic changes in cytokinin pools, cytokinin biosynthesis and degradation were analyzed in the leaves and roots of mature Arabidopsis plants. We found that in leaves of ammonium-grown plants, despite induction of biosynthesis on the expression level, there was no active cytokinin build-up because they were effectively routed toward their downstream catabolites. In roots, cytokinin conjugation was also induced, together with low expression of major synthetic enzymes, resulting in a decreased content of the trans -zeatin form under ammonium conditions. Based on these results, we hypothesized that in leaves and roots, cytokinin turnover is the major regulator of the cytokinin pool and does not allow active cytokinins to accumulate. A potent negative-regulator of root development is trans -zeatin, therefore its low level in mature root tissues of ammonium-grown plants may be responsible for occurrence of a wide root system. Additionally, specific cytokinin enhancement in apical root tips may evoke a short root phenotype in plants under ammonium conditions. The ability to flexibly regulate cytokinin metabolism and distribution in root and shoot tissues can contribute to adjusting plant development in response to ammonium stress. [Display omitted] • Active cytokinin forms do not build up in plant tissues under ammonium nourishment. • In the leaves of ammonium-grown plants, high cytokinin biosynthesis and rapid catabolism indicate rapid hormone turnover rates. • In the roots of ammonium-grown plants, there is low cytokinin biosynthesis and additionally induction of their conjugation. • Low trans-zeatin levels in total root tissues correlate with a wide root system development under ammonium nutrition. • High cytokinin contents were localized in apical root tips and may limit root system elongation in ammonium-fed plants. [ABSTRACT FROM AUTHOR]

• Summarized the effects of APP and its derivatives on the performances of UPR. • Compared the advancement and challenges of different APP modification methods. • Highlighted the future research opportunities of APP for UPR. Ammonium polyphosphate (APP) is a common and commercially available flame retardant for various polymeric materials due to its low cost, ease of proccessing, low toxicity, and environmental friendliness. This mini review focuses on the application of APP in unsaturated polyester resin (UPR) and outlines the flame retardancy, thermal stability, and mechanical properties of the APP-containing UPR composites. As an effective acid source, APP can facilitate the dehydration and carbonization of the UPR matrix during combustion, forming a graphite char layer on the matrix surface to slow down heat exchange and volatile release, thus suppressing the burning reaction. Due to the inorganic properties of APP, microencapsulation and surface decoration are usually conducted on it to enhance its compatibility with UPR and its flame-retardant efficiency. Moreover, different flame-retardant synergists are also applied to strengthen the flame-retardant performance of APP in UPR. In this review, we briefly summarized the influences of microencapsulated APP, surface-decorated APP, and APP/synergist on the properties of UPR, respectively. Then, the advancement and challenges of these APP systems are highlighted, and future research opportunities are also proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A K/Mg/Na ternary compound eluent with molar ratio of 5:6:4 was prepared. • Residual ammonium elution from the rare earth tailings was studied by the eluent. • Highest elution efficiency was obtained due to the synergistic effect. • Ammonium elution was mainly controlled by internal diffusion. • K+, Mg2+, and Na+ were all involved in the elution process and promote the reaction. The development of low-cost compound eluent for the efficient removal of the residual ammonium from the weathered crust elution-deposited rare earth tailings, is highly attractive to meet the growing demands for green metallurgy. Herein, a ternary compound eluent composed of K+, Mg2+, and Na+ was prepared for the first time, and its elution behavior and mechanism for the residual ammonium were investigated in detail. Results showed that the maximum ammonium elution amounts of 1702.9 mg/kg was achieved at a K/Mg/Na molar ratio of 5:6:4, which was much higher than the single eluents of K+ (1264.9 mg/kg), and Mg2+ (1105.6 mg/kg), and Na+ (925.9 mg/kg). In addition, higher eluent concentration and faster flow rate would help to improve the elution efficiency. Besides, the dynamic kinetic study revealed that the residual ammonium elution was controlled by internal diffusion. Moreover, XPS analysis demonstrated that K+, Mg2+, and Na+ ions were all involved in and promoted the residual ammonium elution. The novel ternary compound eluent had great potential application in the residual ammonium removal from the rare earth tailings. [ABSTRACT FROM AUTHOR]

Proper plant growth requires balanced nutrient levels. In this study, we analyzed the relationship between ammonium (NH 4 +) nutrition and calcium (Ca2+) homeostasis in the leaf tissues of wild-type and mutant Arabidopsis specimens provided with different nitrogen sources (NH 4 + and nitrate, NO 3 −). Providing plants with NH 4 + as the sole nitrogen source disrupts Ca2+ homeostasis, which is essential for activating signaling pathways and maintaining the cell wall structure. The results revealed that the lower Ca2+ content in Arabidopsis leaves under NH 4 + stress might result from reduced transpiration pull, which could impair root-to-shoot Ca2+ transport. Moreover, NH 4 + nutrition increased the expression of genes encoding proteins responsible for exporting Ca2+ from the cytosol of leaf cells. Furthermore, overexpression of the Ca2+/H+ antiporter 1 (CAX1) gene alleviates the effects of NH 4 + syndrome, including stunted growth. The oeCAX1 plants, characterized by a lower apoplastic Ca2+ level, grew better under NH 4 + stress than wild-type plants. Evaluation of the mechanical properties of the leaf blades, including stiffness, strength, toughness, and extensibility, showed that the wild-type and oeCAX1 plants responded differently to the nitrogen source, highlighting the role of cell wall metabolism in inhibiting the growth of NH 4 +-stressed plants. [ABSTRACT FROM AUTHOR]

• Co-occurrence of geogenic NH 4 + and P in groundwater was firstly studied. • Four distinct groundwater types regarding NH 4 + and P emerge sequentially. • In low-NH 4 + & high-P type, amorphous Fe(III) reductive dissolution enriches P. • In high-NH 4 + & high-P type, OM degradation and Fe(III) dissolution prevail. • In high-NH 4 + & low-P type, secondary siderite precipitation adsorbs P. High loads of nitrogen (N) and phosphorus (P) in groundwater are a pressing global environmental concern. Geogenic ammonium (NH 4 +) and P anomalies in groundwater as unique forms of contamination, have been extensively reported. However, despite significant efforts on the enrichment of geogenic NH 4 + or P, little is known about their co-occurring characteristics and mechanisms in groundwater. Therefore, focusing on the Dongting Plain (DTP) within the central Yangtze River basin, a typical alluvial-lacustrine plain, this study analyzed hydrogeochemistry, stable carbon isotopes, and dissolved organic matter (DOM) fluorescence. The results revealed a clear correlation between the groundwater DOM humification degree and the redox processes. In different redox processes, four distinct groundwater types emerged sequentially: low-NH 4 + & low-P, low-NH 4 + & high-P, high-NH 4 + & high-P, and high-NH 4 + & low-P. In organic matter (OM) degradation process, when dissolved oxygen and nitrate acted as electron acceptors, the low-NH 4 + & low-P groundwater dominated. The low-NH 4 + & high-P groundwater dominated when Mn(IV) and amorphous Fe(III) (oxyhydr)oxides served as the electron acceptors, where P enrichment was primarily attributed to the reductive dissolution of amorphous Fe(III) (oxyhydr)oxides. The high-NH 4 + & high-P groundwater dominated when SO 4 2-, crystalline Fe(III) (oxyhydr)oxides, and CO 2 served as the electron acceptors. During this phase, OM mineralization resulted in the enrichment of both NH 4 + and P. Furthermore, the reductive dissolution of crystalline Fe(III) (oxyhydr)oxides further increased P concentrations in groundwater. During the strong degradation of OM to the methanogenic stage, two processes occurred simultaneously: anaerobic oxidation of methane and reductive dissolution of Fe(III) (oxyhydr)oxides. These processes led to an increase in the concentration of HCO 3 – and Fe(II) in groundwater. During this phase, large amounts of HCO 3 – and Fe(II) combine to form siderite precipitates. These precipitates adsorb P from the groundwater, eventually leading to a decrease in P concentration and the formation of high-NH 4 + & low-P groundwater. This study offers novel insights into the simultaneous cycling of N and P in Quaternary alluvial-lacustrine aquifer systems. [ABSTRACT FROM AUTHOR]

• Adsorption of binary cations may behave distinctly when containing NH 4 +; • Impacts on cation adsorption follow as charge density > charge location > confinement; • Charge density vs. other factor greatly alters NH 4 + selectivity and recovery & uptake; • Co-ions affect cation selectivity and further regulate NH 4 + uptake and recovery; • Beidellite is only for NH 4 + recovery while montmorillonite is also for NH 4 + uptake. Ammonium (NH 4 +) salts have been extensively applied as nitrogen fertilizers that are essential for plant growth, while also cause a number of environmental problems. NH 4 + uptake by plants and recovery proceed mainly through cation exchange, where clay minerals play a central role. Herein, selective adsorption and release of NH 4 + at smectites/water interfaces are addressed using molecular dynamics simulations. Adsorption behaviors of cations are nearly unperturbed by co-ions, except NH 4 + at montmorillonite surface (0.75 e∙uc-1), and distinct from metal ions, inner-sphere NH 4 + seems non-competitive. Cation adsorption (amount and stability) is affected by charge density > charge location > confinement. Charge location and density reverse NH 4 + vs. K+ adsorption, while NH 4 + above the center of ditrigonal cavities has superior stability and emerges at high charge densities. Charge density rather than location and confinement greatly alters cation selectivity, and montmorillonite with low charge densities is strongly NH 4 +-selective favoring NH 4 + recovery while with high charge densities strongly K+-selective favoring NH 4 + uptake. Impacts of co-ions onto cation adsorption (promoting/inhibiting) are predicted under different conditions that further regulate NH 4 + management; e.g., for montmorillonite (0.75 e∙uc-1), Ca2+/NH 4 + facilitates NH 4 + recovery while K+/NH 4 + facilitates NH 4 + uptake. Impacts of co-ions are altered by charge density > confinement > charge location, and become magnified by stronger confinement and especially at higher charge densities. Montmorillonite is potential for both NH 4 + uptake and recovery depending on magnitude of charge densities and identification of co-ions, while beidellite is applicable only for NH 4 + recovery owing to superior adsorption stability. The comprehensive study for selective adsorption and release of NH 4 + at clay minerals/water interfaces is critical to understand NH 4 + uptake and recovery, and also facilitates development of NH 4 + scavengers. [ABSTRACT FROM AUTHOR]

The work presented here exhibits the function of calcium (Ca) and hydrogen sulfide (H 2 S) in the tolerance of tomato seedlings against NaCl stress. The NaCl (100 mM)-stressed seedlings supplemented with 20 mM Ca, showed a substantial increase in K+/Na+ ratio which however, exhibited a significant decrease when they did not receive Ca. Using plasma membrane inhibitors, it was observed that Ca maintained a higher K+/Na+ ratio by altering K+ and Na+ transport via regulation of Na+-H+ antiport system. However, a reverse trend was noticed when 1 mM hypotaurine (HT; H 2 S scavenger) was applied along with Ca which validates the role of H 2 S in Ca-mediated regulation of K+-Na+ homeostasis. Interactive effect of Ca and H 2 S also improved the activity of the enzymes involved in nitrogen (N) metabolism. Impact of enhanced activity of the enzymes of N metabolism was also reflected in increased inorganic N forms viz. nitrate, nitrite, and ammonium. The stressed seedlings supplied with Ca exhibited higher activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidase) which maintained optimum level of reactive oxygen species (ROS) which was higher in the stressed seedlings that did not receive Ca. A reduction in ROS by Ca led to reduced lipid peroxidation and electrolyte leakage than the NaCl-stressed seedlings. On the other hand, application of HT exhibited a reverse trend in these parameters even in presence of Ca. It signifies H 2 S-dependent functioning of Ca. However, a non-significant effect of HT on root Ca content suggests upstream functioning of Ca to H 2 S. Therefore, it can be postulated that Ca, through regulating N metabolism, protected the seedlings against NaCl-induced constrains in H 2 S-dependent manner, and Ca functions upstream of H 2 S in the regulation of plant adaptive mechanisms to salinity. [Display omitted] • Calcium (Ca) and hydrogen sulfide (H 2 S) regulate K+-Na+ transport under salinity. • Salinity differentially affects the enzymes of nitrogen (N) metabolism and inorganic N. • Ca and H 2 S mitigate NaCl-induced oxidative and osmotic stress. • Ca in association with H 2 S protects membrane damage under salinity. • Ca functions upstream of H 2 S during plant adaptive responses to NaCl stress. [ABSTRACT FROM AUTHOR]

Amine/quaternary ammonium lignin for adsorption of tungsten was synthesized by amination and quaternization from lignin. The adsorbent was characterized by SEM-EDS and FTIR. The effects of pH, initial concentration of tungsten, adsorption time and dosage of adsorbent on the adsorption effect were investigated. The adsorption mechanism was revealed by SEM-EDS and FTIR and XPS. The results showed that amine/quaternary ammonium lignin was loose and rough and contained a large number of phenolic hydroxyl and amine and quaternary ammonium functional groups. Using the optimum conditions, which included the pH of 4.0 and initial tungsten concentration of 800 mg·L−1 and adsorption time of 960 min, the saturated adsorption capacity of 1 g·L−1 amine/quaternary ammonium lignin for tungsten reached 421.68 mg·g−1. The adsorption followed Langmuir model and quasi-second-order kinetic model, indicating that the adsorption was monolayer homogeneous chemisorption. When the total concentration of tungsten was 0.005 mol·L−1 and the value of pH was smaller than 4.7, H 2 W 12 O 40 6− was the existing form of tungsten and was adsorbed by electrostatic attraction of hydrogen bond and coordination with amino and ion exchange with Cl−. H 2 W 12 O 40 6− was adsorbed by electrostatic attraction of hydrogen bond and coordination with amino and ion exchange with Cl−. [Display omitted] [ABSTRACT FROM AUTHOR]

The determination of the penetration depth of treatments is a crucial issue in conservation science for assessing treatments efficacy. Micro-spatially offset Raman spectroscopy (micro-SORS), that permits the non-destructive collection of Raman photons generated under the surface of a turbid material, here has been used to non-destructively retrieve the distribution of oxalates formed after ammonium oxalate (AmOX) treatment on plasters. Two sets of samples treated with AmOX have been studied, namely plaster mock-ups and plaster fragments collected from the painted façades of Palazzo Besta in Teglio (Sondrio, Italy). The evaluation of the distribution of the newly formed oxalates was carried out considering the slope of the oxalates/calcite Raman bands intensity decay trend with increasing micro-SORS defocusing distance. Micro-SORS outcomes were found to be consistent with those obtained with conventional micro-Raman performed on cross-section, confirming the extension of this innovative method to the evaluation of treatments efficacy. [Display omitted] [ABSTRACT FROM AUTHOR]

Nitrogen (N) deficiency is a primary limiting factor for crop production worldwide. Previously, we reported root system architectural modifications of hydroponically cultured foxtail millet [ Setaria italica (L.) Beauv.] to facilitate N translocation under N limitation. Here, we investigated foxtail millet for its shoot adaptation to low N in terms of internal N regulation under hydroponic culture. The results of this study revealed that the shoot N and nitrate (NO 3 −) concentrations significantly declined as compared to control (CK); however, the shoot over-accumulated ammonium (NH 4 +) under low N (LN). N shortage resulted in down-regulation of expressions of SiPetA, SiccsA, SipsbA, SirpoB, SipsaA, SiatpA, Sirps16 , and SiPEPC which, undermined chloroplast functioning and CO 2 assimilation for the provision of carbon skeleton. Carbon deficiency and lower activities of GS decelerated ammonia assimilation and led to over-accumulation of NH 4 + in the LN-shoot, as indicated by lower concentrations of total amino acids. Thus, enhanced GOGAT activity was to assimilate NH 4 + while, those of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) were to scavenge reactive oxygen species (ROS) of NH 4 + toxicity framework. The weakened chloroplast factory eventually minimized photosynthesis and reduced dry mass of the LN shoot. Such regulation of N by the shoot, perhaps, resurrected physiological functions which maintained internal mineral status under nitrogen limitation in foxtail millet. • The shoot over-accumulated ammonium (NH 4 +) under low N. • N shortage undermined chloroplast functioning and provision of carbon skeleton. • Carbon skeleton shortage hampered GOGAT/GS functioning. [ABSTRACT FROM AUTHOR]

In a recent study, Liang, Wilson, and colleagues demonstrated that the H+-selective ion channel OTOP1, responsible for sour taste transduction, also functions as a gustatory sensor for ammonium in mice. Additionally, this research revealed a novel mode of channel activation by intracellular alkalinization, which is conserved across vertebrate species. [ABSTRACT FROM AUTHOR]

In this work, a mixture of (NH 4) 3 SiF 7 /(NH 4) 2 SiF 6 powders was obtained as a by-product of the Li extraction process from α-spodumene aluminosilicate with NH 4 HF 2. The thermal behavior of the powders was analyzed by non-isothermal thermogravimetric experiments. The kinetic parameters that describe the processes involved were obtained using mathematical deconvolution, Friedman's method, combined kinetic analysis, and nonlinear regression optimization. The results show that the process occurs in two partially overlapping steps, the thermal decomposition of (NH 4) 3 SiF 7 into (NH 4) 2 SiF 6 and the subsequent sublimation of (NH 4) 2 SiF 6. The apparent activation energies were 72.6 and 79.8 kJ/mol for steps 1 and 2, respectively. The apparent pre-exponential factors were 1.19 × 106 and 2.50 × 105 s-1, respectively. The kinetic models indicated that Step 1 follows an A2 model, while Step 2 follows an F0 model. Finally, the resulting kinetic parameters allowed the reconstruction of the original experimental curves and obtaining predictions of curves recorded under other heating programs. [Display omitted] • (NH 4) 3 SiF 7 /(NH 4) 2 SiF 6 were obtained by fluorination of spodumene with NH 4 HF 2. • The thermal behavior shows two steps: decomposition and subsequent sublimation. • Ea are 72.6 and 79.8 kJ/mol for decomposition and sublimation, respectively. • Each step is studied by multiple combined kinetic methods. • The kinetic triplets obtained are validated by reconstructions and predictions. [ABSTRACT FROM AUTHOR]

Due to the rapid development of medical industries, wastewater treatment plants have become sinks for residual antibiotics. However, the contribution of novel partial nitrification processes to the bioremediation of antibiotics remains unclear. In this study, the removal rate of a partial nitrification process on the biotransformation of sulfamethoxazole (SMZ) was evaluated. A biological aerated filter made from zeolite successfully achieved stable partial nitrification. A nitrite accumulation percentage (NAP) greater than 85% was obtained when the influent ammonium concentration was increased to 300 mg/L with a nitrogen loading rate of 1.24 kg/(m3 d). Batch tests were performed on support collected from different heights of the up-flow reactor at the end of the pilot monitoring experiment. The maximum ammonium oxidation rate of 5.63 mg/(g VSS·L) in one hour was recorded at a height of 0.32–0.48 m in the reactor, indicating nitrifying bacteria activity link between the free ammonia (FA) and biomass concentration was found. After the addition of SMZ (2.5 mg/L), the NAP declined to approximately 70%, and the abundance of Nitrosomonas (the main ammonia oxidizing bacteria (AOB) genus in the zeolite biological aerated filter (ZBAF)) decreased 7.24–6.10%. Lower abundance and activity of AOB oxidized ineffectively the primary amine of SMZ, which led to lower than 19% of the SMZ removal efficiency. [Display omitted] • AOB was successfully enriched in a zeolite biological aerated filter. • Stable partial nitrification achieved with influent ammonium concentration of 300 mg/L. • The effect of FA inhibition on NOB was related to dose of FA and the biomass concentration. • Microbial analysis showed that SMZ reduced the abundance of AOB in the reactor. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel hybrid packed bed bioreactor (EBC) to treat landfill leachate. • Only 51% nitrogen and 30% carbamazepine (CBZ) were biologically removed. • Coupled biodegradation and ozonation (CBAO) was achieved in the EBC. • CBAO increased nitrogen and CBZ removal to 85% and 100%, respectively. • The abundance of nitrogen removal bacteria increased by 1–4% under ozone exposure. Landfill leachate contains ammonium and micropollutants. Ammonium can be biologically removed but bio-recalcitrant micropollutants removal requires post-treatment like ozonation. This study developed an expanded clay aggregates packed biofilm column (EBC) and demonstrated its feasibility of coupling biodegradation and ozonation (CBAO) to simultaneously remove nitrogen and bio-recalcitrant micropollutants. The first 60 days only had biodegradation process to start the bioreactor. 51 % nitrogen was biologically removed but the removal of micropollutant carbamazepine (CBZ) was only 30 %. From 61 d to 150 d, both biodegradation and ozonation were performed in the EBC. After 48 h-biodegradation, ozone gas was introduced and bubbling through EBC for 30 min to further remove residual micropollutants. At 0.4 gO 3 /gCOD, CBZ were completely removed. The average nitrogen removal efficiency (85 %) was increased by 34 % because the increased abundance of nitrifying and denitrifying bacteria in EBC. This study confirmed the promising potential of the CBAO process for treating landfill leachte. [ABSTRACT FROM AUTHOR]