Common Constituents Research Articles

Alloy design and microstructure of AlxMoV medium-entropy alloys

Incorporating light elements into refractory high-entropy alloys (RHEAs) has been extensively studied to reduce density while maintaining strength. The equiatomic MoV alloy, composed of common RHEA constituents, is promising for forming an isomorphous solid solution and avoiding brittle intermetallic compounds. This study investigates the effects of Al on the equiatomic MoV alloy by fabricating and analyzing MoV, Al15MoV, Al33MoV, and Al50MoV alloys. The crystal structures of MoV, Al15MoV, and Al33MoV were body-centered cubic, while secondary phases were observed in Al50MoV. The Al15MoV and Al33MoV alloys demonstrated higher yield strengths than MoV, despite the addition of soft Al. Notably, the Al15MoV alloy exhibited the best combination of strength and ductility among designed alloys, with a compressive strength of ∼1273 MPa and a ductility of ∼13 %. The primary strengthening mechanism was solid solution strengthening, induced by the significant shear modulus misfit of Al atoms with Mo and V. These novel Al-Mo-V medium-entropy alloys represent a significant advancement in developing lighter RHEAs without compromising mechanical properties, offering a new direction for future RHEA design.

Conditioned place preference with low dose mixtures of α-pyrrolidinopentiophenone (α-PVP) and 3,4-methylenedioxypyrovalerone (MDPV) in male and female Sprague-Dawley rats

Two common constituents of psychoactive “bath salts”, 3,4-methylenedioxypyrovalerone (MDPV) and α-pyrrolidinoipentiophenone (α-PVP) belong to a novel class of synthetic chemicals structurally related to the psychostimulant drug, cathinone. Recreational use of MDPV and α-PVP pose serious health risks, which may be exacerbated by concomitant use of both substances. Preclinical psychopharmacology studies have established that MDPV and α-PVP have high abuse liabilities, comparable to that of cocaine and methamphetamine. Whereas polysubstance use is common among recreational users of synthetic cathinones, preclinical behavioral assays can serve to inform potential behavioral health risks of drug mixtures. This study employed a rodent model of conditioned drug reward, conditioned place preference (CPP), to determine if concurrent treatment with MDPV (1 mg/kg) and α-PVP (1 mg/kg) produced stronger locomotor activation or CPP compared to each individual substance. A secondary aim of this study was to assess sex as variable in the behavioral effects of these substances. Females exhibited a stronger response than males to the locomotor stimulant effects of α-PVP and the α-PVP + MDPV mixture. Additionally, the α-PVP + MDPV mixture produced significantly greater increases in activity compared to either drug alone in females. MDPV and the α-PVP + MDPV mixture established CPP in both sexes, whereas α-PVP alone failed to produce CPP in either sex. These results are consistent with previous preclinical study findings that females may be more susceptible to the psychostimulant effects of these synthetic cathinones. Further investigation is warranted to determine the mechanisms responsible for sex differences in the behavioral effects of these drugs.

Metagenomic discovery of microbial eukaryotes in stool microbiomes.

Host-associated microbiota form complex microbial communities that are increasingly associated with host behavior and disease. While these microbes include bacterial, archaeal, viral, and eukaryotic constituents, most studies have focused on bacteria due to their dominance in the human host and available tools for investigation. Accumulating evidence suggests microbial eukaryotes in the microbiome play pivotal roles in host health, but our understandings of these interactions are limited to a few readily identifiable taxa because of technical limitations in unbiased eukaryote exploration. Here, we combined cell sorting, optimized eukaryotic cell lysis, and shotgun sequencing to accelerate metagenomic discovery and analysis of host-associated microbial eukaryotes. Using synthetic communities with a 1% microbial eukaryote representation, the eukaryote-optimized cell lysis and DNA recovery method alone yielded a 38-fold increase in eukaryotic DNA. Automated sorting of eukaryotic cells from stool samples of healthy adults increased the number of microbial eukaryote reads in metagenomic pools by up to 28-fold compared to commercial kits. Read frequencies for identified fungi increased by 10,000× on average compared to the Human Microbiome Project and allowed for the identification of novel taxa, de novo assembly of contigs from previously unknown microbial eukaryotes, and gene prediction from recovered genomic segments. These advances pave the way for the unbiased inclusion of microbial eukaryotes in deciphering determinants of health and disease in the host-associated microbiome.IMPORTANCEMicrobial eukaryotes are common constituents of the human gut where they can contribute to local ecology and host health, but they are often overlooked in microbiome studies. The lack of attention is due to current technical limitations that are heavily biased or poorly recovered DNA from microbial eukaryotes. We developed a method to increase the representation of these eukaryotes in metagenomic sequencing of microbiome samples that allows to improve their detection compared to prior methods and allows for the identification of new species. Application of the technique to gut microbiome samples improved detection of fungi, protists, and helminths. New eukaryotic taxa and their encoded genes could be identified by sequencing a small number of samples. This approach can improve the inclusion of eukaryotes into microbiome research.

Metal ions-mediated concerted electron-proton transfer enables catalytic oxidation of phenolic contaminants by permanganate

Permanganate has been extensively applied in water treatment due to its ease of handling and high stability. However, the impact of common water constituents, especially metal ions, on permanganate oxidation is poorly understood. Here, we report that many redox-inactive metal ions, such as Ca2+, Mg2+, Zn2+, Cu2+, and Al3+, can enhance the reactivity of permanganate with phenolic compounds. Moreover, the enhancing effects of metal ions are highly pH-dependent with the largest promotion effect obtained at the pH close to phenols’ pKa. Experimental and computational analysis revealed that the oxidation of protonated phenols by permanganate underwent proton-coupled electron transfer (PCET) pathways, regardless of the presence of metal ions. Nonetheless, metal ions could catalyze the concerted electron-proton transfer (CEPT) but exhibited negligible effect on ETPT (electron transfer followed by proton transfer) and PTET (proton transfer followed by electron transfer) reactions, accounting for the pH-dependent effects of metal ions. Correlation between CEPT rate constants and the complexing capability of metal ions with phenols suggested that the co-existing metal ions may coordinate to phenolic O–H group and thus facilitate the CEPT reaction of phenols. This study could shed light on the application of permanganate in real practice and the modulation of CEPT reactions.

Characterization of wind effect on environmental dispersion for a shallow wetland flow

The present work focuses on the dispersion of pollutants under the influence of wind and ecological degradation in a fully developed steady flow for a shallow wetland. The dispersion coefficient is determined by Aris’ method of moments and Meis’ multi-scale analysis. Based on the comparison study, the concentration profiles obtained using multi-scale analysis converge with Aris’ method of moments, indicating that both analytical approaches provide reliable and consistent descriptions of pollutant dispersion in the system. In first-order degradation reaction rates, high degradation rates lead to lower mean concentrations and potentially more pronounced concentration gradients, while low degradation rates result in higher mean concentrations. The critical length of the region influenced by the contaminated cloud is computed analytically. It shows that for the common contaminant constituent lead (Pb), initially, it increases gradually to reach the maximum; after that as time increases, it decreases to zero under wind conditions.

A Mathematical Model of Diel Activity and Long Time Survival in Phototrophic Mixed-Species Subaerial Biofilms

Subaerial biofilms (SAB) are intricate microbial communities living on terrestrial surfaces, of interest in a variety of contexts including cultural heritage preservation, microbial ecology, biogeochemical cycling, and biotechnology. Here we propose a mathematical model aimed at better understanding the interplay between cyanobacteria and heterotrophic bacteria, common microbial SAB constituents, and their mutual dependence on local environmental conditions. SABs are modeled as thin mixed biofilm-liquid water layers sitting on stone. A system of ordinary differential equations regulates the dynamics of key SAB components: cyanobacteria, heterotrophs, polysaccharides and decayed biomass, as well as cellular levels of organic carbon, nitrogen and energy. These components are interconnected through a network of energetically dominant metabolic pathways, modeled with limitation terms reflecting the impact of biotic and abiotic factors. Daily cylces of temperature, humidity, and light intensity are considered as input model variables that regulate microbial activity by influencing water availability and metabolic kinetics. Relevant physico-chemical processes, including pH regulation, further contribute to a description of the SAB ecology. Numerical simulations explore the dynamics of SABs in a real-world context, revealing distinct daily activity periods shaped by water activity and light availability, as well as longer time scale survivability conditions. Results also suggest that heterotrophs could play a substantial role in decomposing non-volatile carbon compounds and regulating pH, thus influencing the overall composition and stability of the biofilm.

Gastrointestinal digestion of yerba mate, rosemary and green tea extracts and their subsequent colonic fermentation by human, pig or rat inocula

Polyphenolic compounds are common constituents of human and animal diets and undergo extensive metabolism by the gut microbiota before entering circulation. In order to compare the transformations of polyphenols from yerba mate, rosemary, and green tea extracts in the gastrointestinal tract, simulated gastrointestinal digestion coupled with colonic fermentation were used. For enhancing the comparative character of the investigation, colonic fermentation was performed with human, pig and rat intestinal microbiota. Chemical analysis was performed using a HPLC system coupled to a diode-array detector and mass spectrometer. Gastrointestinal digestion diminished the total amount of phenolics in the rosemary and green tea extracts by 27.5 and 59.2 %, respectively. These reductions occurred mainly at the expense of the major constituents of these extracts, namely rosmarinic acid (−45.7 %) and epigalocatechin gallate (−60.6 %). The yerba mate extract was practically not affected in terms of total phenolics, but several conversions and isomerizations occurred (e.g., 30 % of trans-3-O-caffeoylquinic acid was converted into the cis form). The polyphenolics of the yerba mate extract were also the least decomposed by the microbiota of all three species, especially in the case of the human one (−10.8 %). In contrast, the human microbiota transformed the polyphenolics of the rosemary and green extracts by 95.9 and 88.2 %, respectively. The yerba mate-extract had its contents in cis 3-O-caffeoylquinic acid diminished by 78 % by the human microbiota relative to the gastrointestinal digestion, but the content of 5-O-caffeoylquinic acid (also a chlorogenic acid), was increased by 22.2 %. The latter phenomenon did not occur with the rat and pig microbiota. The pronounced interspecies differences indicate the need for considerable caution when translating the results of experiments on the effects of polyphenolics performed in rats, or even pigs, to humans.

Application of the EBSD Technique in the Study of Porosity and Permeability in Deformation Bands in Sandstone.

Deformation bands are common constituents of porous clastic fluid reservoirs. Various techniques have been used to study deformation band structure and the associated changes in porosity and permeability. However, the use of electron backscatter diffraction technique is limited. Thus, more information is needed regarding the crystallographic relationships between detrital crystals, which can significantly impact reservoir rock quality. We employ microscopic and microstructural investigation techniques to analyze the influence of cataclastic deformation bands on pore space. Porosity measurements of the Cretaceous Ilhas Group sandstone in NE Brazil, obtained through computerized microtomography, indicate that the undeformed domains exhibit a total porosity of up to 13%. In contrast, this porosity is slightly over 1% in the deformation bands. Scanning electron microscopy analyses revealed the presence of grain fragmentation and dissolution microstructures, along with cement-filling pre-existing pores. The electron backscatter diffraction analyses indicated extensive grain fragmentation and minimal contribution from intracrystalline plasticity as a deformation mechanism. However, the c axes of quartz crystals roughly align parallel to the orientation of the deformation band. In summary, we have confirmed and quantified the internal changes in a deformation band cluster, with grain size reduction and associated compaction as the main mechanism supported by quartz cementation.

Efficient Nickel and Cobalt Recovery by Metal-Organic Framework-Based Mixed Matrix Membranes (MMM-MOFs).

Green energy transition has supposed to give a huge boost to the electric vehicle rechargeable battery market. This has generated a compelling demand for raw materials, such as cobalt and nickel, which are key common constituents in lithium-ion batteries (LIBs). However, their existing mining protocols and the concentrated localization of such ores have made cobalt and nickel mineral conundrums, and their supplies experience shortages, which threaten to slow the progress of the renewable energy transition. Aiming to contribute to the sustainable recycling of these valuable metals from LIBs and wastewater, in this work, we explore the use of four mixed matrix membranes (MMMs) embedding different metal-organic frameworks (MOFs), i.e., MIL-53(Al), MIL-53(Fe), MIL-101(Fe), and {SrIICuII 6[(S,S)-serimox]3(OH)2(H2O)}·39H2O (SrCu 6 Ser) in polyether sulfone (PES), for the recovery of cobalt(II) and nickel(II) metal cations from mixed cobalt-nickel aqueous solutions containing common interfering ions. Whereas the neat PES membrane slightly contributes to the adsorption of metal ions, showing reduced removal efficiency values of 10.2 and 9.5% for Ni(II) and Co(II), respectively, the inclusion of MOFs in the polymeric matrix substantially improves the adsorption performances. The four MOF@PES MMMs efficiently remove these metals from water, with MIL-53(Al)@PES being the one that presents better performance, with a removal efficiency up to 95% of Ni(II) and Co(II). Remarkably, SrCu 6 Ser@PES exhibits outstanding selectivity toward cobalt(II) cations compared to of nickel(II) ones, with removal efficiencies of 63.7 and 15.1% for Co(II) and Ni(II), respectively. Overall, the remarkable efficiencies, versatility, high environmental robustness, and cost-effective synthesis shown by this family of MOF@PES MMMs situate them among the best adsorbents for the extraction of this kind of contaminants.

Carbonyl Chemistry for Advanced Electrochemical Energy Storage Systems.

On the basis of the sustainable concept, organic compounds and carbon materials both mainly composed of light C element have been regarded as powerful candidates for advanced electrochemical energy storage (EES) systems, due to theie merits of low cost, eco-friendliness, renewability, and structural versatility. It is investigated that the carbonyl functionality as the most common constituent part serves a crucial role, which manifests respective different mechanisms in the various aspects of EES systems. Notably, a systematical review about the concept and progress for carbonyl chemistry is beneficial for ensuring in-depth comprehending of carbonyl functionality. Hence, a comprehensive review about carbonyl chemistry has been summarized based on state-of-the-art developments. Moreover, the working principles and fundamental properties of the carbonyl unit have been discussed, which has been generalized in three aspects, including redox activity, the interaction effect, and compensation characteristic. Meanwhile, the pivotal characterization technologies have also been illustrated for purposefully studying the related structure, redox mechanism, and electrochemical performance to profitably understand the carbonyl chemistry. Finally, the current challenges and promising directions are concluded, aiming to afford significant guidance for the optimal utilization of carbonyl moiety and propel practicality in EES systems.

Tagpyrrollins A and B and Tagpyrrollidone A: Three Pyrrole Steroid Analogues with AKR1B1-Targeting Inhibitory Activity from the Sponges Stylissa massa and Pseudospongosorites suberitoides.

Pyrrole alkaloids (PAs) are a diverse class of natural products with complex carbon frameworks and broad bioactivities that are usually derived from marine sponges. Stylissa massa and Pseudospongosorites suberitoides are two independent sponges collected from the South China Sea in 2013 and 2018, respectively. We discovered PAs are common constituents in both two sponges; more specifically, S. massa produces pyrrole-imidazole alkaloids, and P. suberitoides contains pyrrolidone alkaloids. In this study, three pyrrole steroid metabolites were obtained. Compounds 1 and 2 are a pair of epimers sharing a new 5/7/5/6/6 pentacyclic structural configuration, and compound 3 has a new rigid 5/6/6 tricyclic structure. Interestingly, their scaffolds all possess a 6/6 bicyclic system on the featured classic pyrrole/pyrrolidone skeletons, so-dubbed tagpyrrollins A and B (1 and 2, respectively) and tagpyrrollidone A (3). From a biosynthetic viewpoint, 4,5-dihydroxypent-2-enal probably plays a crucial role in constructing these pyrrole steroid analogues. Based on our previous study on the inhibitory activity of spongiacidin targeting AKR1B1, a drug target for the treatment of chronic diabetic complications, in this study we found that tagpyrrolin A (1) also exhibits an inhibitory effect against AKR1B1.

Evaluating the role of dissolved silica for dolomite formation in evaporitic environments: Insights from prolonged laboratory experiments

The mineral Dolomite CaMg(CO3)2 is a common constituent of sedimentary rocks. Despite centuries of research, the mechanism of its formation remains elusive and debated. Recent studies have shown the presence of silica in solution promote the incorporation of Mg into the carbonate mineral, forming crystal phases that may be precursors to dolomite. The goal of this study was to evaluate with laboratory experiments whether dissolved silica may play a role for dolomite formation in sabkha (i.e., salt flats) environments. Several models for dolomite formation are based on the studies of sabkhas, which are often cited as modern analogue for ancient dolomite-rich sedimentary sequences. We performed long-incubation time (i.e., up to 600 days) laboratory precipitation experiments at 30 °C with solution mimicking the sabkha pore waters (characterized by a salinity of 23 % and Mg: Ca ratio of 15) to which we added different concentrations of Si. Our results revealed a positive correlation (p-value <0.001) between Si concentration in solution and the mol% Mg of the carbonate minerals forming in the experiment. With 2 mM of Si, the bulk precipitate was comprised of 90 % stoichiometric dolomite with possible signs or ordering. Moreover, the rhombohedral morphology of the crystals is analogue to that of natural dolomite previously described from sabkha sediments. Our results suggest that dissolved Si may play an important role for dolomite formation in evaporitic environments.

Activation of peracetic acid by electrodes using biogenic electrons: A novel energy- and catalyst-free process to eliminate pharmaceuticals

Peracetic acid (PAA) has received increasing attention as an alternative oxidant for wastewater treatment. However, existing processes for PAA activation to generate reactive species typically require external energy input (e.g., electrically and UV-mediated activation) or catalysts (e.g., Co2+), inevitably increasing treatment costs or introducing potential new contaminants that necessitate additional removal. In this work, we developed a catalyst-free, self-sustaining bioelectrochemical approach within a two-chamber bioelectrochemical system (BES), where a cathode electrode in-situ activates PAA using renewable biogenic electrons generated by anodic exoelectrogens (e.g., Geobacter) degrading biodegradable organic matter (e.g., acetic acid) in wastewater at the anode. This innovative BES-PAA technique achieved 98 % and 81 % removal of 2 µM sulfamethoxazole (SMX) in two hours at pH 2 (cation exchange membrane) and pH 6 (bipolar membrane) using 100 μM PAA without external voltage. Mechanistic studies, including radical quenching, molecular probe validation, electron spin resonance (ESR) experiments, and density functional theory (DFT) calculations, revealed that SMX degradation was driven by reactive species generated via biogenic electron-mediated OO cleavage of PAA, with CH3C(O)OO• contributing 68.1 %, •OH of 18.4 %, and CH3C(O)O• of 9.4 %, where initial formation of •OH and CH3C(O)O• rapidly reacts with PAA to produce CH3C(O)OO•. The presence of common water constituents such as anions (e.g., Cl−, NO3−, and H2PO4−) and humic acid (HA) significantly hinders SMX removal via the BES-PAA technique, whereas CO32− and HCO3− ions have a comparatively minor impact. Additionally, the study investigated the removal of various pharmaceuticals present in secondary treated municipal wastewater, attributing differences in removal efficiency to the selective action of CH3C(O)OO•. This research demonstrates a novel PAA activation method that is ecologically benign, inexpensive, and capable of overcoming catalyst deactivation and secondary pollution issues.

Regional Differences in Microbial Infiltration of Brain Tissue from Alzheimer's Disease Patients and Control Individuals.

Alzheimer's disease (AD) is characterized by cognitive decline and neuropathology including amyloid beta (Aβ) plaques and neurofibrillary tangles (tau). Factors initiating or driving these pathologies remain unclear, though microbes have been increasingly implicated. Our data and others' findings indicate that microbes may be common constituents of the brain. It is notable that Aβ and tau have antimicrobial properties, suggesting a response to microbes in the brain. We used 16S rRNA sequencing to compare major bacterial phyla in post-mortem tissues from individuals exhibiting a range of neuropathology and cognitive status in two brain regions variably affected in AD. Our data indicate that strong regional differences exist, driven in part by the varied presence of Proteobacteria and Firmicutes. We confirmed our data using ELISA of bacterial lipopolysaccharide (LPS) and lipoteichoic acid in the same brain tissue. We identified a potential association between the composition of phyla and the presence of neuropathology but not cognitive status. Declining cognition and increasing pathology correlated closely with serum LPS, but not brain levels of LPS, although brain LPS showed a strong negative correlation with cerebral amyloid angiopathy. Collectively, our data suggest a region-specific heterogeneity of microbial populations in brain tissue potentially associated with neurodegenerative pathology.

Material basis and mechanism of Bletillae Rhizoma for melasma, gastrointestinal hemorrhage, lung cancer and bronchoplumonary inflammation as "homotherapy for heteropathy" based on UHPLC-Q-Exactive Orbitrap HRMS coupled with network pharmacology and molecular docking

Based on UHPLC-Q-Exactive Orbitrap HRMS coupled with the network pharmacology and molecular docking, the common material basis and molecular mechanisms of Bletillae Rhizoma for melasma, gastrointestinal hemorrhage, lung cancer and bronchoplumonary inflammation as &quot;homotherapy for heteropathy&quot; were explored. The fingerprint of 17 batches of Bletillae Rhizoma from different areas was established using HPLC, and the similarity analysis was carried out. The common chemical components of the 17 batches of Bletillae Rhizoma were identified using UHPLC-Q-Exactive Orbitrap HRMS. Depending on the bioavailability and drug-like properties of the common components, the active chemical components were screened, and then their protein targets were collected using the Traditional Chinese Medicine Database and Analysis Platform(TCMSP) and SwissTargetPrediction database. The protein targets related to diseases were retrieved from the databases DrugBank, TTD and GeneCards to produce a Venn diagram. The shared targets were obtained between drugs and diseases as &quot;homotherapy for heteropathy&quot; targets. The protein-protein interaction(PPI) was analyzed with the STRING database, and KEGG and GO analyses of the &quot;homotherapy for heteropathy&quot; targets were performed using the Bioconductor database. Cytoscape 3.7.2 software was employed to construct the &quot;chemical components of Bletillae Rhizoma-homotherapy for heteropathy targets&quot; network and PPI network, and topological analysis was conducted to screen out the key active chemical components and core targets. Finally, the affinity between the active components and core targets was evaluated using the molecular docking by AutoDock Vina 4.2.6, which verified the interaction between them. Thirteen common peaks were identified by fingerprint chromatography, and the similarity between different batches was 0.941-0.998. Fifty-three chemical components were identified by mass spectrometry in Bletillae Rhizoma, and 18 common chemical constituents were obtained in the 17 batches of Bletillae Rhizoma. Network pharmacologic screening showed that the pharmacodynamic substances of Bletillae Rhizoma for melasma, gastrointestinal hemo-rrhage, lung cancer and bronchoplumonary inflammation with &quot;homotherapy for heteropathy&quot; were 11 compounds, such as polysaccharides, biphenanthrenes, dihydrophenanthrenes and bibenzyls. There were 42 common targets identified for the treatment of different diseases. These targets were involved in biological processes such as cell response to chemical stress, reactive oxygen species and positive regulation of protein kinase B signal transduction. They were also involved in 121 signaling pathways, encompassing vital pathways such as PI3K-Akt, ErbB, Rap1, FoxO, MAPK and estrogen. Molecular docking results showed a strong affinity between the key active components and the core targets. This study provides a preliminary explanation of how Bletillae Rhizoma exerts its therapeutic effect on chloasma, gastrointestinal hemorrhage, lung cancer, and bronchopneumonic lesions as &quot;homotherapy for heteropathy&quot; through a combined action involving multiple components, targets, and pathways. These findings offer a certain theoretical basis for the further deve-lopment and application of Bletillae Rhizoma.

Melting Behavior of a CaO–SiO2–Al2O3 Flux with Varying MnO Concentration for Use in Fusion Welding of Low‐Carbon Steel

CaF2 has been a very common constituent in the fluxes used for welding of low‐carbon steel plates, owing to its strong ability to lower the liquidus temperature as well as viscosity of the molten flux. But the adverse impact of fluoride evaporation from molten slag on the health of operating personnel and the environment has prompted a worldwide effort to replace CaF2 with more benign constituents. Three compositions with varying MnO concentration in the CaO–MnO–SiO2–Al2O3 system, identified in the current work, have shown promise in terms of ability to control oxygen transfer and modify inclusion generation in the molten metal during the welding of low carbon low alloy steels. However, the melting behavior of a flux needs to be established before recommending its use for welding. Three compositions, with varying MnO concentration, are chosen in the current work. Aided by experimental measurements using high‐temperature microscopy, DTA and simulations using the commercially available thermodynamic package FactSage (version 8.3), this work aims to understand the melting characteristics of the developed fluxes. These characteristics seem to be comparable with a commercial CaF2‐containing welding flux, used as a reference for comparison. In addition, simulations using FactSage suggest that transfer of dissolved O, Si and Mn to the weld metal, while using these fluxes, would be benefitial to performance of the welded joint.

A metal-free Z-scheme PPy/MCN heterojunction for antibiotic removal via synergism of photocatalysis and peroxymonosulfate activation

Developing an active and synergistic system based on photocatalysis and peroxymonosulfate (PMS) activation is considered an effective strategy for efficient removal of antibiotics. However, photocatalytic heterojunctions generally comprise metallic catalysts that can cause metal leaching and secondary pollution, and a clear understanding of the synergy between photocatalysis and PMS activation is still missing. Herein, a metal-free Z-scheme polypyrrole (PPy)/melamine-derived graphitic carbon nitride (MCN) heterojunction photocatalyst was synthesized via calcination and in-situ loading for catalyzing the degradation of ciprofloxacin (CIP) and other emerging pollutants in a visible light-emitting diode (LED)/PMS synergistic system, which showed a significantly higher activity than the single LED and PMS systems. The optimal 0.5 %PPy/MCN (0.5 % is the mass ratio of PPy in the mixture of PPy/MCN) performed well under a wide pH range (3–11), while exhibiting superior anti-interference for common water constituents and outstanding reusability and stability. The 0.5 %PPy/MCN/LED/PMS synergistic system showed the highest kinetic constant (0.0643 1/min), which increased 3.00, 6.77 and 2.91-fold over the 0.5 %PPy/MCN/PMS, 0.5 %PPy/MCN/LED, and MCN/LED/PMS system, respectively. Mechanistic investigation and theoretical calculations revealed that PPy, with its high conductivity and strong light absorption ability, facilitated the generation and separation of e−/h+ in the 0.5 %PPy/MCN/LED/PMS system and activated PMS for generating reactive species such as 1O2, which degraded cCIP together with h+. Furthermore, electron transfer pathway (ETP) was elucidated using electrochemical characterizations. CIP was degraded via ring opening, cleavage hydroxylation, ammonia oxidation and elimination reactions, which substantially reduced the toxicity of CIP. Overall, this study may help the rational design of metal-free catalysts and provide a deep insight for the LED/PMS synergistic mechanisms.

The Electrostatic Induction Characteristics of SiC/SiC Particles in Aero-Engine Exhaust Gases: A Simulated Experiment and Analysis

This study investigates the electrostatic induction characteristics of silicon carbide-fiber-reinforced silicon carbide (SiC/SiC) particles within aero-engine exhaust gases using a dedicated J20 turbojet engine experimental platform. Our comprehensive experiments explored the electrostatic properties of SiC/SiC particles under varying engine operational states—specifically focusing on different thermal conditions, particle mass concentrations, particle sizes, and exhaust gas velocities compared to those of common engine exhaust constituents like carbon (C) and iron (Fe) particles. The results demonstrate that SiC/SiC particles consistently maintain a stable positive charge across varied temperatures, significantly diverging from the behaviors of carbon (C) and iron (Fe) particles. Additionally, our findings reveal that higher mass concentrations of SiC/SiC particles, smaller particle sizes within a certain range, and greater exhaust gas velocities of the aero-engine all lead to increased particle charge and more pronounced electrostatic induction characteristics. This study highlights the potential of electrostatic sensors for the early detection and diagnosis of failures in aero-engines, offering crucial insights into the development of more resilient real-time aero-engine health monitoring systems.

Novel Hybrid Copper-Based Electrode for Non-Enzymatic Electrochemical Lactic Acid Sensing in Milk Samples

A novel developed non-enzymatic electrochemical sensor was designed for the detection of lactic acid (LA) in perishable products, with a focus on monitoring milk spoilage. The sensor utilizes a hybrid copper-based electrode consisting of cuprous oxide (Cu2O), copper oxide (CuO), and copper hydroxide (Cu(OH)2), which collectively contribute to enhanced performance through their synergistic effects. Cyclic voltammetric studies revealed distinct oxidation peaks associated with LA detection, highlighting the superior catalytic effect of the Cu2O/CuO/Cu(OH)2 electrode compared to CuO alone. Further optimization of the metal loading on the electrode surface led to improve LA sensing properties. The sensor exhibited a wide linear response range (0.25–7 mM), high sensitivity (817.66 μA·mM−1·cm−2), and a low limit of detection (0.25 mM). Selectivity tests indicated negligible interference from common dairy product constituents, while stability tests showed consistent performance over a 3 week storage period (100% stability). The practical usability of the sensor was demonstrated through the quantitative analysis of LA in pasteurized milk, with recovery values ranging from 99.7% to 106.9%, confirming the feasibility of the sensor for real sample analysis. The developed multiphase copper-based electrode presents a promising platform for the sensitive and reliable detection of LA within the dairy industry.

Cone and fruit impacts on understory flammability depend on traits and forest floor coverage

BackgroundUnderstory flammability is affected by abscised plant tissue. Extensive research has shown how interspecific differences in leaf litter traits affect flammability; however, leaves represent only one component of the litter layer. Cones and fruit are also common constituents of the forest floor, yet surprisingly little is known about how flammability is affected by their presence. In this study, we ask how flammability is affected by cones and fruit trait differences, coverage differences, and varying species and coverage combinations. To address these questions, we compared cone and fruit morphological and chemical traits among longleaf pine, loblolly pine, shortleaf pine, sweetgum, post oak, and water oak. We also used burn trials to compare fire behavior of single and mixed-species treatments at three coverage levels (10% of plot area (low), 30% (medium), and 50% (high)) integrated within a common mixed-litter layer under field conditions in central Alabama, USA.ResultsLike other plant tissues, cone/fruit dry matter, carbon, and lignin content promote fuel consumption and flame height, while nitrogen suppresses flammability. Single-species treatments produced distinct patterns in fire behavior, with longleaf pine cones consistently showing higher percent fuel consumption, flame height, and maximum smoldering temperature than sweetgum capsular heads. Mixed-species treatment results were less consistent; however, at high coverage, a representative upland three-way mixture (longleaf pine + sweetgum + post oak) showed significantly greater fuel consumption and flame height relative to a bottomland three-way mixture (loblolly pine + sweetgum + water oak) at high coverage. Medium cone/fruit coverage maximized flammability in most single and multi-species treatments and produced non-additive fuel consumption in mixtures containing longleaf pine and sweetgum.ConclusionOur results confirm that individual species’ cone and fruit flammability often parallels that of litter. Fire behavior in mixture is generally driven by the most flammable constituent species, but this result changes with cone and fruit coverage. Collectively, these results indicate that cones/fruit identity and coverage play an important role in understory flammability and should be integrated into fire behavior modeling efforts in monocultures and mixtures.