Search Results (489)

In our research we analyzed a series of water quality parameters and conducted a metagenomic analysis of the microbial community in the Chishui River (in southwestern China), aiming to explore the microbial driving mechanisms of the phosphorus cycle in the river ecosystem. The research results indicated that the concentrations of total phosphorus (TP) and soluble reactive phosphorus (SRP) were higher in summer, suggesting seasonal differences in exogenous input and water body biogeochemical processes. The concentration of manganese (Mn) is higher in autumn, and it shows a significant positive correlation with Soluble reactive phosphorus (SRP). This may indicate the contribution of endogenous release from sediments to phosphorus in the water body. There were significant differences in the abundance of phosphorus cycling functional genes between summer and autumn. For example, in summer, the abundances of high-affinity phosphate transporter (pstB), inorganic phosphate dissolution (pqqC), and polyphosphate decomposition (ppx) were significantly higher. This might be to adapt to high productivity and the potential lack of phosphorus, or it could be that the microorganisms carrying these genes have a greater advantage during the summer. In contrast, the relative abundance of phosphonate (phn) and glycerophosphate (ugpQ) was significantly higher in autumn, indicating that the metabolic focus of the microorganisms has shifted towards the utilization of organic phosphorus, or that the microorganisms that are adept at utilizing organic phosphorus have taken the dominant ecological position in this situation. Moreover, the analysis of the microbial community showed that the Proteobacteria phylum (Pseudomonad phylum) was the main phylum, and the relative abundance of key functional bacterial genera (such as Limnohabitans, Acinetobacter) reflected seasonal changes, which was consistent with the above functional gene patterns. Spearman correlation analysis indicated that environmental physical and chemical parameters (such as iron, dissolved oxygen, dissolved organic carbon, pH value) jointly regulated the composition and distribution of phosphorus cycling functional genes. Our research results demonstrated that the microbial community plays a crucial regulatory role in the biogeochemical cycle of the river ecosystem through the transformation of functional genes and the changes in community structure. The research results emphasize that attention must be paid to the phosphorus cycling process regulated by microorganisms and its impact, in order to control water body eutrophication and maintain the stability of the ecosystem. Full article

Thermophilic cyanobacteria are key models for thermotolerance and a promising source of thermophilic bioresources. Yet the subcellular basis of their stress resilience remains poorly resolved. Here, we focus on intracellular polyphosphate (polyP)-rich granules, termed “stabilisomes,” which have been implicated in stress adaptation. The lack of a high-purity, structure-preserving isolation method has been a major technical bottleneck hindering the elucidation of this resilience mechanism. This study describes a robust, structure-preserving purification strategy, boosting the granule-to-protein yield by over 10,000-fold compared with conventional methods. The specificity and structural integrity of this method are supported by the specific enrichment of complex proteomic (937 proteins) and metabolomic (1076 metabolites) signatures. Building on this, subsequent quantitative analysis across cyanobacteria at 7 hot spring sampling sites revealed a conserved core chemical composition dominated by polyphosphate (~21–36%), proteins (~10–20%), amino acids (~7–18%), and lipid components (~12–21%). The variability in abundance across species suggests a dynamic adjustment of these stabilizing components consistent with specific micro-environmental conditions. This work provides a robust bioseparation platform for prokaryotic organelles, offering a critical tool for investigating cyanobacterial resilience and developing novel biomaterials. Full article

Hydrophobic silica aerogels (SAs) have attracted much attention because of their excellent thermal insulation performance and have potential applications in energy conservation and emission reduction. However, the organic groups on its surface are flammable, which brings security risks and limits its application scope. In this study, two kinds of ammonium polyphosphate (APP) with different polymerization degrees, namely low-polymerization-degree APP (LAPP) and high-polymerization-degree APP (HAPP), were introduced into SA to prepare APP/SA composites, to improve the thermal safety of the materials. The results showed that APP with two polymerization degrees significantly delayed the initial decomposition and peak temperature of heat flow, and HAPP reduced the gross calorific value by 31.01% at most, which is 29.04% greater than that of LAPP, indicating that the effect of HAPP was slightly better than that of LAPP. With the increase in APP with two polymerization degrees, the density increased and the porosity decreased: LAPP system was 0.095–0.196 g/cm³ and 96.0–91.0%. Both made the thermal conductivity increase only slightly (up to 26.8 mW/m/K), but the sample still maintained excellent thermal insulation and hydrophobicity, which indicated that the addition of APP improved the thermal safety performance of SA while maintaining its basic excellent performance. This strategy provides an effective and simple way to improve the flame retardancy of SA, which makes SA more widely used in fields with strict requirements on thermal safety. Full article

A major challenge for halogen-free flame retardants is their tendency to migrate under high-temperature and high-humidity environments. For instance, the combination of aluminum diethylphosphinate (ADP) and melamine polyphosphate (MPP) used in polyamide 66 (PA66) easily migrated to the surface, leading to a white and frost-like appearance. To address this issue, a core–shell elastic flame retardant (SiR@FR) was prepared via a solution deposition method, wherein a polymethylsiloxane (SiR) layer was encapsulated on the surface of ADP and MPP. This shell not only improved the hydrophobicity of the FR but also the toughness of PA66. Experimental results demonstrated that PA66 with 9-SiR@FR (PA66-5) exhibited excellent migration resistance, with no visible surface whitening after 480 h of aging at 85 °C and 85% relative humidity. Meanwhile, PA66-5 displayed outstanding flame retardancy, achieving a UL-94 V-0 rating with an approximate 65% decrease in peak heat release rate compared with control PA66. Furthermore, SiR@FR enhanced the toughness of PA66 by alleviating stress concentration, resulting in a 21% increase in impact strength. This study presents a simple but reliable encapsulation strategy for fabricating flame-retardant PA66 composites that combine superior migration resistance and satisfactory mechanical properties, showing promising potential for demanding applications requiring long-term usability and stability. Full article

This study presents a rapid and efficient laboratory-scale process for removing lead from Pb–Sb alloy melts using a composite H₃PO₄–(NaPO₃)₆ flux. Thermodynamic analysis was combined with experimental investigation to elucidate the influence of key parameters on lead removal behavior. The Wilson equation was employed to describe the non-ideal behavior of the Pb–Sb system, enabling estimation of equilibrium lead contents and providing theoretical support for interpreting experimental trends. Under the investigated conditions (1073 K, H₃PO₄/(NaPO₃)₆ mass ratio of 2:1, and a holding time of 10 min), the Pb mass fraction was reduced from 10.0 wt.% to 0.018 wt.%, corresponding to a lead removal efficiency of 99.86%. Compared with the traditional refining processes, this method shortens the processing time and avoids the use of volatile gas reagents, demonstrating its potential for lead–antimony separation. The results provide thermodynamic and experimental insight into phosphate-based refining of crude antimony. Full article

Flame-retardant microcapsules were prepared using a urea–melamine–formaldehyde (UMF) shell and boric acid-crosslinked ammonium polyphosphate (APP) as the core to improve the dispersion stability and processing compatibility of phosphorus-based flame retardants. Thermal analysis showed that the microcapsules exhibited initial mass loss near 80 °C due to moisture evaporation and shell relaxation, while APP-related degradation occurred at higher temperatures, indicating delayed release of the core and enhanced thermal resistance through encapsulation. Scanning electron microscopy confirmed the formation of microcapsules, and morphological changes before and after combustion suggested the development of protective char layers. Boron-containing residues are expected to contribute to char stabilization through the formation of B–O–P structures during heating. The flame-retardant properties were evaluated using limiting oxygen index, smoke density, and vertical burning tests. Although the limiting oxygen index slightly decreased due to reduced accessible APP content, stable burning behavior was maintained, and characteristic char formation was observed after combustion. These results indicate that the UMF/APP microcapsules can improve thermal stability and handling of phosphorus-based flame retardants. The microencapsulation approach presented here may provide practical advantages for polymer processing and surface-coating applications. Full article

Studying the origin of life requires identifying chemical and physical processes that could have supported early self-replicating and evolving molecular systems. Besides the requirement of information storage and transfer, an essential aspect is an energy source that could have thermodynamically driven the formation and replication of these molecular assemblies. Chemical energy sources such as cyclic trimetaphosphate are attractive because they could drive replication with relatively simple catalysts. Here, we focus on cyclic trimetaphosphate (cTmp), and compare its solubility in water to linear triphosphate, pyrophosphate, and phosphite when Mg²⁺ or Ca²⁺ are present. These solubilities are important for facilitating the reactions under prebiotically plausible conditions. The results showed that cTmp was soluble even at molar concentrations of Mg²⁺ and little precipitation with 200 mM Ca²⁺. In contrast, pyrophosphate and linear triphosphate precipitated efficiently even at low divalent metal ion concentrations. The precipitation of phosphate was pH-dependent, showing similar precipitation with Mg²⁺ and Ca²⁺ at a prebiotically plausible pH of 6.5. Phosphite was soluble at high Mg²⁺ concentrations but started precipitating with increasing Ca²⁺ concentration. At conditions that model Archaean seawater, cTmp was the most soluble of these compounds. Together, this experimental overview may help to identify promising conditions for lab-based investigations of phosphate-based energy metabolisms in early life forms. Full article

Enhancing the flame retardancy of polymeric materials by adding only eco-friendly ammonium polyphosphate (APP) while simultaneously maintaining high-temperature resistance has become a challenge. Talcum has been introduced as a cooperative agent into the silicone rubber/APP system to investigate the effect of talcum on flame retardancy, thermal stability, and high-temperature resistance. The machining process induces the orientation of talcum in the system. The ceramifiable silicone rubber blends containing oriented talcum (e.g., sample SA₆T₄) exhibited superb flame retardancy, including an LOI of 29.4%, a UL-94 rating of V-0, and a peak heat release rate (PHRR) of 250.2 kW·m⁻². More importantly, the blends present excellent thermal stability and high-temperature resistance, characterized by outstanding self-supporting properties and dimensional stability. Based on the structural analysis of the blends and their residues, the made of action for the improved flame retardancy may be attributed to the formation of a compact barrier layer. This layer is formed by oriented talcum platelets combined with phosphoric acid, from the thermal decomposition of APP, promoting crosslinking, thereby achieving a good inhibition barrier to inhibit heat feedback from the condensation zone. The excellent thermal stability and high-temperature resistance of the ceramifiable silicone rubber blends may be ascribed to a cooperative effect between APP and talcum at high temperatures, which facilitates the formation of ceramic structures. The novel ceramifiable silicone rubber composite has potential applications as flame-retardant sealing components for rail transit equipment and encapsulation materials for new energy battery modules. Full article

Inorganic polyphosphate is highly conserved, critical, yet poorly understood polymer that regulates diverse cellular functions in mammals. Its importance is well established in coagulation, inflammation, mitochondrial function, and stress responses, though the molecular mechanisms for these effects remain only partly understood. Fundamental questions also persist regarding its physiological concentration, chain-length distributions, and the mechanisms that regulate its behavior in specific cellular compartments. Progress is limited by the absence of a known mammalian polyphosphate-synthesizing enzyme. Despite this, recent studies have broadened the scope of polyphosphate biology, suggesting roles in protein phase separation, ATP-independent chaperone activity, metabolic regulation, and intracellular signaling. Polyphosphate modulates the mitochondrial permeability transition pore through calcium-dependent regulation and activates factor XII in coagulation. Findings have also introduced potential connections between polyphosphate and processes such as neurodegeneration, cancer, and tissue regeneration. Despite this expanding landscape, many biological effects remain difficult to interpret due to incomplete mapping of protein targets and longstanding technical limitations in detecting and quantifying polyP. This review integrates molecular protein-interaction mechanisms with compartment-specific functions and disease physiology, providing a clearer mechanistic framework while identifying key conceptual and methodological gaps and outlining priorities for advancing polyphosphate research in mammalian systems. Full article

In the article we investigated the effectiveness of a synergistic system designed to reduce the fire hazard of flexible polyurethane (PUR) foams. The examined system consisted of a carbon-based filler graphene (G), carbon nanotubes (CNTs), or expanded graphite (EG) combined with melamine polyphosphate (MPP). The investigated polyurethane foams (PUR) were synthesized at room temperature via a polycondensation reaction between a polyol and an isocyanate, with an OH: NCO molar ratio of 2:1. Both the carbon fillers and melamine polyphosphate were homogeneously dispersed within the polyol component. Thermogravimetric analysis (TGA), cone calorimetry, and microcalorimetry were used to evaluate the influence of the fillers on the thermal stability and flammability of the PUR foams. The toxicity of the gaseous products was assessed using a coupled TG-gas analysis system, while the optical density of the evolved gases was determined using a Smoke Density Chamber (SDC). The obtained results demonstrated that the applied synergistic carbon-phosphorus filler system significantly reduced the fire hazard of the tested PUR foams. In particular, the EG5-MPP system enabled the formation of self-extinguishing materials. Full article

Chemorepulsion mechanisms for eukaryotic cells are poorly understood. We performed proteomics and phosphoproteomics to elucidate how Dictyostelium discoideum responds to its two endogenous chemorepellent signals, the protein AprA and inorganic polyphosphate (polyP). AprA and polyP affected levels of more than 200 proteins, with an overlap of both upregulating 25 proteins and downregulating two proteins. Two proteins were upregulated by AprA but downregulated by polyP, while two others showed the opposite trend. Surprisingly, many of the AprA- and polyP-regulated proteins are associated with RNA metabolism and ribosomes. AprA increased phosphorylation of 15 proteins and decreased phosphorylation of 36 proteins. PolyP increased phosphorylation of 12 proteins and decreased phosphorylation of 12 proteins. As expected, the two chemorepellents affected phosphorylation of signal transduction/ motility proteins, but unexpectedly affected phosphorylation of RNA-associated proteins. Both AprA and polyP decreased phosphorylation of five proteins including the Ras-interacting protein RipA and guanine nucleotide exchange factors (GEFs) such as the RacGEF GxcT. Mutants lacking RipA or GxcT were unresponsive to both AprA and polyP chemorepulsion. Together, this work supports the idea that rather than activating the same chemorepulsion mechanism, AprA and polyP activate only partially overlapping chemorepulsion mechanisms, and identifies two new components that are used by both chemorepellents. Full article

The present work deals with the preparation and characterization of fire-retardant acrylonitrile–butadiene–styrene (ABS) foams incorporating 25 wt% of a phosphorus flame-retardant (PFR) system formed by 50% of ammonium polyphosphate (APP) and 50% of aluminum diethylphosphinate (AlPi). To further enhance performance, 5 wt% of the PFR was replaced by either montmorillonite (MMT) or layered double hydroxide (LDH) nanoparticles, maintaining the overall FR content constant. The formulations were prepared by melt blending, and foams were produced using a one-step supercritical carbon dioxide (sCO₂) dissolution foaming process. The incorporation of the PFR, alone or partially replaced by nanoclays, resulted in foams with smaller cell sizes and higher cell nucleation densities compared to pure ABS, with cell sizes reducing from 60 μm to as low as 40 μm and cell densities reaching values > 10⁷ cells/cm³. The presence of LDH notably modified the thermal decomposition of ABS–PFR, increasing the temperature at 5% mass loss (T_5%) by more than 10 °C and the amount of formed residue by more than 15%. The ABS–PFR/LDH foam also showed a higher glass transition temperature (3 °C increase) and a higher specific storage modulus (920 MPa·cm³/g, a more than 40% increase). Cone calorimetry revealed a very significant reduction in the peak of the heat release rate (PHRR) and increased residue formation for ABS–PFR compared to ABS (from 1672 kW·m⁻² to as low as 483 kW·m⁻²). LDH nanoparticles further decreased HRR during the early quasi-static combustion stage of foams, indicating a more effective condensed-phase flame-retardant action than MMT. Full article

The influence of light on nutrient removal in microalgae–bacteria biofilm systems containing polyphosphate-accumulating organisms (PAOs) remains unclear under low-carbon-to-nitrogen (C/N) ratio wastewater. This study investigated the effects of different light energy density (Es, 16.23–1101.61 J/gVSS) on the system performance and microbial community of a phototrophic simultaneous nitrification–denitrification phosphorus removal biofilm (P-SNDPRB) system treating wastewater with C/N ratios of 3.19–3.92. At Es below 367.22 J/gVSS, denitrification was the main nitrogen removal pathway, exceeding 82% total nitrogen removal. With increasing Es, nitrogen assimilation increased, while total nitrogen removal declined, remaining above 65%. Phosphorus removal was dependent on phosphorus-accumulating metabolism, achieving exceeding 90% phosphorus removal at Es below 367.22 J/gVSS. However, effluent phosphorus concentrations exceeded 0.5 mg/L at higher Es due to elevated glycogen-accumulating organism (GAO) activity and photoinhibition. Excessive light induced reactive oxygen species accumulation, inhibiting cellular activity and causing bacterial death in flocs. In contrast, the biofilm mitigated light stress, preserving the activity of PAOs, GAOs, ammonia-oxidizing bacteria, and nitrite-oxidizing bacteria across different Es levels. These findings demonstrate that P-SNDPRB systems exhibit resilience to fluctuating light conditions, enabling effective nutrient removal in low-C/N wastewater and offering insights into optimizing light management for microalgae-assisted treatment processes. Full article

D-Allulose is a promising low-calorie rare sugar with significant health benefits. However, its industrial production is hindered by the low catalytic efficiency (≤33% conversion) and unfavorable equilibrium of the key enzyme, D-allulose 3-epimerase (DAE). To overcome this thermodynamic bottleneck, an in vitro synthetic enzymatic cascade based on a phosphorylation–dephosphorylation strategy was constructed. This engineered system comprises four synergistically operating enzymes: D-allulose-3-epimerase (DAE), L-rhamnulose kinase (RhaB), polyphosphate kinase (PPK), and acid phosphatase (AP). Through rational design and systematic optimization, the cascade achieved an exceptional 84.5% conversion yield from 50 mM D-fructose. Importantly, the system also maintained high conversion rates of 64.4% and 61.1% at high D-fructose loadings (50–100 g L⁻¹). This performance, together with the integration of a low-cost PolyP₆–PPK ATP regeneration module, underscores the potential industrial applicability of the proposed cascade strategy. Full article

Conditions have been established for the direct reaction of thiosemicarbazides with carboxylic acids in the presence of polyphosphate ester (PPE) to synthesize 1,2,4-triazole-3-thiol derivatives. The synthesis involves two consecutive steps: (i) acylation of the thiosemicarbazide with a carboxylic acid in chloroform in the presence of PPE at 90 °C using a hydrothermal reaction vessel, followed by (ii) cyclodehydration of the acylation product by treatment with an aqueous alkali solution. Using this new synthetic approach, 15 derivatives of 1,2,4-triazole-3-thiol were obtained, five of which were synthesized for the first time. The structures of the synthesized compounds were confirmed by NMR spectroscopy and mass spectrometry. Full article