High pH Research Articles

Studies on enhancement of solubility and dissolution properties of Nimodipine by solid dispersion technique

Nimodipine, a member of calcium channel blocker, specifically binds to L-type voltage-gated calcium channels. The maximum solubility of nimodipine was found at pH 1.2 and solubility decreases up to pH 4.0. At a pH 6.0 and higher pH, solubility reduces drastically. Suitable solid dispersion systems of nimodipine with PVP-K30 and maltodextrin were prepared by physical mixture, solvent evaporation and kneading methods at 1:1 and 1:3 drug: carrier. Drug content, saturation solubility, FTIR, and in-vitro dissolution were studied. The drug content was uniform, solubility of the drug increased linearly as a function of the carrier concentration and method. The FTIR studies indicates no chemical interaction between drug and polymer. The DP60 and DE60 values of solid dispersion systems prepared by solvent evaporation and kneading method were significantly higher (P<0.05) when compared to DP60 and DE60 values of physical mixture and pure Nimodipine. The dissolution follows first order model and obeyed Hixson- Crowell’s cube root law.

Soil properties constrain forest understory plant distributions along an elevation gradient.

Projections of spatial biodiversity dynamics under climate warming are often based on models including only climate variables, and when non-climatic factors (e.g. soil) are included, data are often at much coarser spatial resolutions than those experienced by plants. Field studies along elevation gradients permit the gathering of detailed soil data, while still covering a wide climatic gradient. Here, an intensive field survey of four spring forest herbs along an elevation gradient showed that soil properties had substantial impacts on the occurrence/abundance of all species, and that soil effects were more pronounced at higher elevations. For Trillium erectum and Claytonia caroliniana, very infrequent occurrences at high elevation were strongly associated with rare microsites with high pH or nutrients. In a seven-year transplant experiment with T. erectum, we found that individuals grew to much smaller sizes at high than low elevation, suggesting that environmental factors rather than dispersal limitation constrain the species' upper range limit, despite substantial warming in recent decades. Our study demonstrates that soil factors interact strongly with climate to determine plant range limits along climatic gradients. Unsuitable soils for plants at high elevations or latitudes may represent an important constraint on future plant migration and biodiversity change. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

Characterization of slightly acidic electrolyzed water on effective disinfection against microbial safety and retention of phenolic compound in SAEW treated fresh romaine lettuce

Abstract This study investigated the effects of processing parameters, specifically the low rate and the combination of diluted HCl and salt (NaCl) at different concentrations, on the properties of the slightly acidic electrolyzed water (SAEW) that was produced. The properties of the SAEW that were analyzed included pH, oxidation-reduction potential (ORP), available chlorine concentrations (ACC), and generated hypochlorous acid (HClO) concentration. NaCl alone resulted in the lowest pH (<4) and the highest ORP values (>1000 mV). Increasing HCl concentrations significantly raised pH levels to greater than 5 and lowered ORP values of SAEW, with the highest pH (5.7) observed with 1.5% HCl and 5% NaCl. The highest HClO concentration of 19.65±1.03 mg/L was obtained with 1.5% HCl:5% NaCl. Interestingly, the concentration of NaCl showed no significant effects on the production of HClO. Furthermore, different concentrations of combined NaCl and HCl significantly influenced the inactivation efficiency on total aerobic bacteria count and changes in phenolic compound content. Increasing HCl concentrations from 0.5% to 2.0% led to an increase in the reduction of aerobic bacteria counts from 2.51 to 4.22 log CFU/g with 5% NaCl and from 2.49 to 3.52 log CFU/g with 10% NaCl. Flow rates significantly contributed to the change in HClO formation and altered the properties of the produced SAEW. Results indicated that SAEW treatment significantly reduced total aerobic bacteria counts. The lower flow rates (0.3 L/min) produced the highest log reductions. Additionally, SAEW treatment led to a reduction in phenolic content, even though considerable amount was retained at lower HClO concentrations. These findings offer valuable information on optimizing SAEW treatment protocols for enhancing microbial safety and extending the shelf life of fresh produce, while considering the impact on the content of phenolic compounds.

Effect of low dose honey on the apoptosis and inflammation gene expression in corneal limbal stem cells and keratocytes and its efficacy as an ophthalmic formulation in the treatment of dry eye: in-vitro and clinical study

BackgroundThe use of honey as an eye treatment encounters challenges due to its high osmolarity, low pH, and difficulties in sterilization. This study addresses these issues by employing a low concentration of honey, focusing on both in-vitro experiments and clinical trials for treating dry eye disease in corneal cells.MethodsIn the in-vitro experiment, we investigated the impact of a 1% honey-supplemented medium (HSM) on limbal stem cells (LSCs) and keratocytes using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and real-time polymerase chain reaction (PCR) for BCL-2, BAX, and IL-1β gene expression. Simultaneously, in the clinical trial, 80 participants were divided into two groups, receiving either a 1% w/v honey ophthalmic formulation or a placebo for 3 months. Study outcomes included subjective improvement in dry eye symptoms, tear break-up time (TBUT), and Schirmer’s test results.ResultsMTT results indicated that 1% HSM did not compromise the survival of corneal cells and significantly reduced the expression of the IL-1β gene. Additionally, participants in the honey group demonstrated a higher rate of improvement in dry eye symptoms and a significant enhancement in TBUT values at the three-month follow-up. However, there was no significant difference between the study groups in terms of Schirmer’s test values. No adverse events were observed or reported.ConclusionIn conclusion, 1% honey exhibits anti-inflammatory and anti-infective properties, proving effective in ameliorating dry eye symptoms and enhancing tear film stability in patients with dry eye disease.Clinical Trial Registration: https://irct.behdasht.gov.ir/trial/63800.

Response of spiny cocklebur (Xanthium spinosum) and common cocklebur (X. strumarium) seed germination to environmental and soil factors

Context Seed germination and seedling emergence are affected by many environmental factors. Knowledge regarding factors affecting seed germination of spiny cocklebur (Xanthium spinosum L.) and common cocklebur (X. strumarium L.) could help determine their potential distribution and control strategies. Aims The present study was conducted to investigate the effect of key environmental factors on seed germination and seedling emergence of spiny cocklebur and common cocklebur. Methods Seed germination of spiny cocklebur and common cocklebur was tested at various constant and alternating temperatures, pH, salinity and moisture stress. The effect of flooding height, burial depth and soil type on seedling emergence was also investigated. Key results The optimum constant temperature for germination of spiny cocklebur was 25°C, and 35°C and higher for common cocklebur. Under alternating temperature, maximal germination was at 25/15°C and 35/15°C for spiny cocklebur and common cocklebur, respectively. Maximum germination of both spiny cocklebur and common cocklebur was at neutral pH. Spiny cocklebur germination was not suppressed as much by lower and higher pH or by an increasing salinity as was common cocklebur germination. Conclusions Common cocklebur appears to be better adapted to warmer environments than is spiny cocklebur, but less so to a broad range of soil pH and salinity stress. Implications The different germination responses of common cocklebur and spiny cocklebur to the environmental factors of temperature, pH and salinity imply that the two species may occupy different niches across the landscape. Our knowledge of these responses can help in identifying potential areas for invasion for increased monitoring and management.

The effect of near-infrared low-level light on the in vitro quality of platelets during storage.

Near-infrared (NIR) light has been successfully applied to improve the quality of mouse platelets during storage. Because it is suspected that the mitochondria contain the primary photon acceptor, we hypothesized that human platelets for transfusion may be affected similarly and could benefit from NIR light treatment. The optimal light dose was determined using portions of platelet concentrates (PCs) in PAS-E. A pool-and-split design was used to prepare PCs in PAS-E or plasma (n = 6). On day 1, one unit of both pairs was illuminated with 830 nm light (light-emitting diodes, 15 J/cm2). PCs were stored at 22°C and sampled regularly for analysis. Data were compared with their corresponding controls with a paired two-sided t-test. Illuminated platelets in PAS-E were less activated with significantly lower CD62P expression (day 8: 10.8 ± 1.8 vs. 12.2 ± 2.6, p < 0.05) and lower Annexin A5 binding (day 8: 11.8 ± 1.9 vs. 13.1 ± 2.4, ns). They produced significantly less lactate resulting in a higher pH (days 6-10). ATP content and mitochondrial membrane potential were not affected. Although these trends were also observed for PCs in plasma, the differences did not reach statistical significance as compared with the control group. Our study demonstrates that the glycolysis rate of human platelets can be modulated through the use of NIR, possibly through mitochondrial aerobic metabolism, but this requires confirmation. If NIR illumination can be further optimized, it may potentially become a useful tool in situations in which glycolysis and platelet activation are exacerbated.

Dmxl1 is an Essential Mammalian Gene that is Required for V-ATPase Assembly and Function In Vivo

Abstract The proton pumping V-ATPase drives essential biological processes, such as acidification of intracellular organelles. Critically, the V-ATPase domains, V1 and VO, must assemble to produce a functional holoenzyme. V-ATPase dysfunction results in cancer, neurodegeneration, and diabetes, as well as systemic acidosis caused by reduced activity of proton-secreting kidney intercalated cells (ICs). However, little is known about the molecular regulation of V-ATPase in mammals. We identified a novel interactor of the mammalian V-ATPase, Drosophila melanogaster X chromosomal gene-like 1 (Dmxl1), aka Rabconnectin-3A. The yeast homologue of Dmxl1, Rav1p, is part of a complex that catalyzes the reversible assembly of the domains. We, therefore, hypothesized that Dmxl1 is a mammalian V-ATPase assembly factor. Here, we generated kidney IC-specific Dmxl1 knockout (KO) mice, which had high urine pH, like B1 V-ATPase KO mice, suggesting impaired V-ATPase function. Western blotting showed decreased B1 expression and B1 (V1) and a4 (VO) subunits were more intracellular and less colocalized in Dmxl1 KO ICs. In parallel, subcellular fractionation revealed less V1 associated B1 in the membrane fraction of KO cells relative to the cytosol. Furthermore, a Proximity Ligation Assay (PLA) performed using probes against B1 and a4 V-ATPase subunits also revealed decreased association. We propose that loss of Dmxl1 reduces V-ATPase holoenzyme assembly, thereby inhibiting proton pumping function. Dmxl1 may recruit the V1 domain to the membrane and facilitate assembly with the VO domain and in its absence V1 may be targeted for degradation. We conclude that Dmxl1 is a bona-fide mammalian V-ATPase assembly factor.

In Vitro and In Silico Characterization of N-Formylated Two-Peptide Bacteriocin from Enterococcus faecalis CAUM157 with Anti-Listeria Activity.

Enterococcus faecalis CAUM157 (KACC 81148BP), a Gram-positive bacteria isolated from raw cow's milk, was studied for its bacteriocin production. The antimicrobial activity of CAUM157 was attributed to a two-peptide class IIb bacteriocin with potent activity against food-borne pathogen Listeria monocytogenes and periodontal disease-causing pathogens (Prevotella intermedia KCTC 15693T and Fusobacterium nucleatum KCTC 2488T). M157 bacteriocins exhibit high temperature and pH stability and resist hydrolytic enzyme degradation and detergent denaturation, potentially due to their structural conformation. Based on amino acid sequence, M157A and M157B were predicted to be 5.176kDa and 5.182kDa in size, respectively. However, purified bacteriocins and chemically synthesized N-formylated M157 peptides both showed 5.204kDa (M157A) and 5.209kDa (M157B) molecular mass, confirming the formylation of the N-terminal methionine of both peptides produced by strain CAUM157. Furthermore, the strain demonstrated favorable growth and fermentation with minimal bacteriocin production when cultured in whey-based media, whereas a 1.0% tryptone or soytone supplementation resulted in higher bacteriocin production. Although Ent. faecalis CAUM157 innately harbors genes for virulence factors and antimicrobial resistance (e.g., tetracycline and erythromycin), its bacteriocin production is valuable in circumventing the need for live microorganisms, particularly in food applications for pathogen control.

Highly Efficient Acidic Electrosynthesis of Hydrogen Peroxide at Industrial-Level Current Densities Promoted by Alkali Metal Cations.

Acidic H2O2 synthesis through electrocatalytic 2e- oxygen reduction presents a sustainable alternative to the energy-intensive anthraquinone oxidation technology. Nevertheless, acidic H2O2 electrosynthesis suffers from low H2O2 Faradaic efficiencies primarily due to the competing reactions of 4e- oxygen reduction to H2O and hydrogen evolution in environments with high H+ concentrations. Here, we demonstrate the significant effect of alkali metal cations, acting as competing ions with H+, in promoting acidic H2O2 electrosynthesis at industrial-level currents, resulting in an effective current densities of 50‒421 mA cm‒2 with 84‒100% Faradaic efficiency and a production rate of 856‒7842 μmol cm-2 h-1 that far exceeds the performance observed in pure acidic electrolytes or low-current electrolysis. Finite-element simulations indicate that high interfacial pH near the electrode surface formed at high currents is crucial for activating the promotional effect of K+. In situ attenuated total reflection Fourier transform infrared spectroscopy and ab initio molecular dynamics simulations reveal the central role of alkali metal cations in stabilizing the key *OOH intermediate to suppress 4e- oxygen reduction through interacting with coordinated H2O.

Highly Efficient Acidic Electrosynthesis of Hydrogen Peroxide at Industrial‐Level Current Densities Promoted by Alkali Metal Cations

Acidic H2O2 synthesis through electrocatalytic 2e– oxygen reduction presents a sustainable alternative to the energy‐intensive anthraquinone oxidation technology. Nevertheless, acidic H2O2 electrosynthesis suffers from low H2O2 Faradaic efficiencies primarily due to the competing reactions of 4e– oxygen reduction to H2O and hydrogen evolution in environments with high H+ concentrations. Here, we demonstrate the significant effect of alkali metal cations, acting as competing ions with H+, in promoting acidic H2O2 electrosynthesis at industrial‐level currents, resulting in an effective current densities of 50‒421 mA cm‒2 with 84‒100% Faradaic efficiency and a production rate of 856‒7842 μmol cm‐2 h‐1 that far exceeds the performance observed in pure acidic electrolytes or low‐current electrolysis. Finite‐element simulations indicate that high interfacial pH near the electrode surface formed at high currents is crucial for activating the promotional effect of K+. In situ attenuated total reflection Fourier transform infrared spectroscopy and ab initio molecular dynamics simulations reveal the central role of alkali metal cations in stabilizing the key *OOH intermediate to suppress 4e– oxygen reduction through interacting with coordinated H2O.

Folding Kinetics and Volume Variation of the β-Hairpin Peptide Chignolin upon Ultrafast pH-Jumps.

In-depth characterization of fundamental folding steps of small model peptides is crucial for a better understanding of the folding mechanisms of more complex biomacromolecules. We have previously reported on the folding/unfolding kinetics of a model α-helix. Here, we study folding transitions in chignolin (GYDPETGTWG), a short β-hairpin peptide previously used as a model to study conformational changes in β-sheet proteins. Although previously suggested, until now, the role of the Tyr2-Trp9 interaction in the folding mechanism of chignolin was not clear. In the present work, pH-dependent conformational changes of chignolin were characterized by circular dichroism (CD), nuclear magnetic resonance (NMR), ultrafast pH-jump coupled with time-resolved photoacoustic calorimetry (TR-PAC), and molecular dynamics (MD) simulations. Taken together, our results present a comprehensive view of chignolin's folding kinetics upon local pH changes and the role of the Tyr2-Trp9 interaction in the folding process. CD data show that chignolin's β-hairpin formation displays a pH-dependent skew bell-shaped curve, with a maximum close to pH 6, and a large decrease in β-sheet content at alkaline pH. The β-hairpin structure is mainly stabilized by aromatic interactions between Tyr2 and Trp9 and CH-π interactions between Tyr2 and Pro4. Unfolding of chignolin at high pH demonstrates that protonation of Tyr2 is essential for the stability of the β-hairpin. Refolding studies were triggered by laser-induced pH-jumps and detected by TR-PAC. The refolding of chignolin from high pH, mainly due to the protonation of Tyr2, is characterized by a volume expansion (10.4 mL mol-1), independent of peptide concentration, in the microsecond time range (lifetime of 1.15 μs). At high pH, the presence of the deprotonated hydroxyl (tyrosinate) hinders the formation of the aromatic interaction between Tyr2 and Trp9 resulting in a more disorganized and dynamic tridimensional structure of the peptide. This was also confirmed by comparing MD simulations of chignolin under conditions mimicking neutral and high pH.

Clinical characteristics and outcome of non-acute myocardial syndrome cardiogenic shock in comparison to its ischaemic aetiology

Abstract Funding Acknowledgements None. Background The mortality in cardiogenic shock (CS) remains high but the report mostly concerns CS in the course of acute myocardial syndrome (ACS). There is limited data about non- ischaemic CS. Purpose The aim of this study was to analyse the clinical characteristics, treatments and outcomes in patients with non-ACS CS in comparison to ischemic aetiology CS. Methods 80 patients with an average age of 62 ± 13 years (81 % male) with CS admitted in 2021 and 2022 to tertiary hospital were divided into 2 subgroups: non-acute myocardial infarction cardiogenic shock (non-ACS-CS) consisted of 16 individuals (20%) and CS in the course of ACS (ACS-CS) consisted of 64 (80%) individuals. The main cause of CS in non-ACS group was worsening of previously diagnosed heart failure 11 (14%). Results Patients from non-ACS group were younger 52±16 vs. 65±11 years old, p=0.005. There were no differences in baseline heart rate 90 [72;100] vs. 95 [80;107] beats per minute and mean artery pressure 89 [73;97] vs. 80 [70;97] mmHg for non-ACS-CS vs. ACS-CS, respectively all p&amp;gt;0.05. Patients from non-ACS-CS group had lower baseline troponin level 0.29 [0.04;0.96] vs. 7.05 [0.69;57.4] ng/mL, p=0.003, white blood cell count 11 [9;13] vs. 15 [10;19] × 109/L; p=0.035, procalcitonin 0.06 [0.05;0.28] vs. 0.69 [0.10;2,48] ng/mL, p=0.001 and higher pH 7.4 [7.3;7.5] vs. 7.2 [7.0;7.4], p=0.012 in blood gas analysis when compared with ACS-CS. There were no significant differences in the severity of the shock according to Society for Cardiovascular Angiography and Interventions (SCAI) SHOCK classification among the groups: from C: 1 (6%) vs. 6 (10%), D: 11 (69%) vs. 27 (42%), E: 4 (25%) vs. 31 (48%), respectively for non-ACS vs. ACS-shock. The non-ACS-CS was more often treated with V-A ECMO 10 (63%) vs. 20 (32%) in ACS-CS, p=0.024. The overall number of in-hospital deaths was 57 (71%). The non-ACS-CS group had significantly lower in-hospital mortality 8 (50%) compared to the ACS-CS patients 49 (77%), p=0.034. Conclusion Patients experiencing non-ACS-CS were younger, have lower levels of inflammatory markers and a higher pH in blood gas analysis at admission. Despite more favourable biomarker profile non-ACS-CS group was treated more aggressively and had significantly lower in-hospital mortality rates when compared with patients facing ACS-CS, which indicates the need to look at CS differently depending on its aetiology.

Distinguishing direct N2O emissions from 15N-labeled manure compost, urea, and maize roots in a field study

Nitrous oxide (N2O) emissions from agricultural activities are a significant contributor to global anthropogenic N2O emissions. Sustainable agriculture practices, including using manure compost to replace nitrogen (N) fertilizers, can reduce chemical fertilizer use and minimize negative impacts on soil health and water quality. However, the direct contributions of manure compost to N2O emissions have not been fully studied. We conducted a field study to distinguish the direct contributions of manure compost, urea, and residual maize roots to N2O emissions in an integrated crop-livestock agricultural system in Shandong Province, China. Using the 15N-labeling technique, we found that the majority (93.3%) of cumulative N2O emissions originated from the soil and other unaccounted sources. Notably, manure compost contributed 1.3%, while current-year urea, residual urea with root exudates, and maize root accounted for 3.4%, 1.9%, and 0.03% of cumulative N2O, respectively. Our results also demonstrated that applying manure compost in combination with urea resulted in lower seed yield-scaled N2O emissions (0.046 g N2O-N kg−1 seed) compared to applying urea alone, even when the total N input was identical, suggesting the potential of manure compost in a more sustainable agriculture model. The low emission factor of manure compost (0.005%) compared to urea (0.019%) supports this potential, indicating the slow-release nature of manure may mitigate N2O while maintaining crop yield. Additionally, the overall low emissions may be attributed to the relatively high soil pH (8.17), which influences the denitrification product ratio, favoring the conversion of N2O to N2. Our study provides valuable insights into the factors contributing to N2O emissions in integrated crop-livestock farming systems, and highlights the importance of distinguishing multiple sources of N2O emissions to develop effective strategies for reducing emissions while promoting sustainable agriculture.

The investigation on stress mechanisms of Sepia esculenta larvae in the context of global warming and ocean acidification

Sepia esculenta is a tasty and nutritious cephalopod. But the trend toward global warming is accelerating with massive emissions of greenhouse gases. An increase in seawater temperature and a decrease in pH are a great challenge for artificial breeding and culture of S. esculenta. In this study, we investigated the contingency mechanism of S. esculenta larvae under both high temperature and low pH conditions by transcriptome analysis. A total of 1235 DEGs were identified. functional enrichment analysis results suggest that high temperature and low pH conditions led to malignant proliferation in exceptional cells of S. esculenta larvae. A comprehensive analysis of the KEGG signaling pathway and protein-protein interaction network (PPI) identified sixteen key genes under both high temperature and low pH conditions. The three genes with the highest quantities of interactions or involved in more KEGG signaling pathways were identified as hub genes affecting normal physiological processes in S. esculenta. In this study, the effects of global warming and ocean acidification on the metabolism and immunity of S. esculenta larvae were preliminarily investigated to provide necessary help for S. esculenta captive breeding in the face of global climate change.

Mechanistic basis of the dynamic response of TWIK1 ionic selectivity to pH

Highly selective for K+ at neutral pH, the TWIK1 channel becomes permeable to Na+ upon acidification. Using molecular dynamics simulations, we identify a network of residues involved in this unique property. Between the open and closed states previously observed by electron microscopy, molecular dynamics simulations show that the channel undergoes conformational changes between pH 7.5–6 involving residues His122, Glu235, Lys246 and Phe109. A complex network of interactions surrounding the selectivity filter at high pH transforms into a simple set of stronger interactions at low pH. In particular, His122 protonated by acidification moves away from Lys246 and engages in a salt bridge with Glu235. In addition, stacking interactions between Phe109 and His122, which stabilize the selectivity filter in its K+-selective state at high pH, disappear upon acidification. This leads to dissociation of the Phe109 aromatic side chain from this network, resulting in the Na+-permeable conformation of the channel.

Analysis of the influence of water qualities on the strength of concrete

Concrete is commonly employed in construction for its tremendous compressive strength, despite its low tensile strength. This study aimed at analyzing the strength of concrete when mixed with water of varying qualities. Before concrete is formulated, tests are done on the aggregates to ascertain the right proportions but not on water used. Dreux-Gorrise concrete formulation method was employed. CAMWATER (tap water), rain water and water from a free-flowing river was used to cast concrete samples after which it was crushed to obtain 7 and 28 day resistances. The water qualities varied were pH and hardness. Hydrochloric acid and sodium hydroxide were used to vary the pH of water. Results showed an increase in concrete strength as a function of increase in water pH. Water with a high pH resulted in concrete with an appreciable strength value while acidic water resulted in very low strength values. The usage of hard water for mixing concrete resulted in a strength value lower than with soft water. Conclusively, water quality has an effect on the strength of concrete. Therefore, it is advisable to use water with a high pH value for mixing concrete, preferring rainwater over tap water when mixing concrete due to hardness of water.

Effect of pH on degradation and mineralization of catechol in calcium-aid ozonation: Performance, mechanism and products analysis

Catechol, common in industrial wastewater, is very toxic and non-biodegradable, and its desirable removal is still a challenge. Catalytic ozonation as an effective advanced oxidation process, however was limited by the application of intricately fabricated catalysts. Herein, catalytic ozonation by OH– (generated by common sodium hydroxide) with the aid of calcium was developed for catechol degradation and mineralization in this study. The removal performance, mechanism and products were investigated. The results showed that ozonation at pH 12.5 could achieve complete catechol removal and excellent mineralization (maximum of 75 % COD removal efficiency) within 15 min. The adorable effect of calcium for enhanced organics removal was observed at pH 12.5, with the formation of precipitates as well. Catechol and COD removal were fitted to the pseudo-first-order kinetic model, while the reaction constant was increased by higher pH and calcium concentration. The results of quenching experiment and EPR affirmed •OH and •O2– radicals were pivotal for the enhanced organics removal. In addition, DFT calculation revealed the O atoms were reactive sites for electrophilic and radical attack via molecular electrostatic potential, highest occupied molecular orbital, lowest unoccupied molecular orbital and Fukui index. UPLC-Q-TOF-MS analysis revealed the intermediate products and verified the brilliant performance of catalytic ozonation. According to reactive sites and intermediates identification, the degradation pathway of catechol was proposed. As tawny precipitate appeared after reaction, the characteristics of insoluble product was analyzed using FTIR, XRD and XPS. The component of the precipitate was recognized as calcium oxalate and calcium carbonate, accompanied by the decreased Ca2+ concentration at high pH, which declared the enhanced removal was linked to the precipitation of Ca2+. Finally, toxicity assessment stated the lower acute toxicity, bioconcentration factor, developmental toxicity and mutagenicity of intermediates, indicating that calcium-aid ozonation catalyzed by high pH was useful for both catechol degradation and toxicity reduction. This study provides a reference for understanding the performance and mechanism of catechol degradation. More importantly, as an environmentally friendly process, catalytic ozonation possesses a great application potential for treatment of wastewater containing metal ions in terms of simultaneous removal of organics and metal ions.

The coupling of sulfide and Fe-Mn mineral promotes the migration of lead and zinc in the redox cycle of high pH floodplain soils

In this study, we investigated the impact of fluctuating water levels on the distribution of lead (Pb) and zinc (Zn) in soil and sediments at a historical Pb-Zn smelting site along the Xiangjiang River. Despite the high pH levels (7 to 11) in the study area, which generally inhibits heavy metal solubility, we found that regular changes in water levels still affect Pb-Zn movement. Soil analysis revealed distinct redox zones within the unconfined aquifer, as shown by the variable Fe/Mn and Ce/Ce* ratios. Advanced techniques such as Mn K-edge XAFS, Mössbauer spectroscopy, and TOF-SIMS indicated persistent Fe-Mn redox cycling and highlighted the presence of Pb and Zn-rich manganese oxides near sulfur-bearing minerals. These findings suggest that acidic microzones produced by the oxidation of sulfur-bearing minerals become "refuges" for microbial and heavy metal activity. Considering that sulfur-containing minerals are widespread waste types in nonferrous metal smelting sites, these findings are instructive for a better understanding of the transformation mechanisms of heavy metal ions in nonferrous metal smelting-polluted environments and for guiding pollution remediation strategies.

Fractionation of biomass-burning smoke-derived dissolved organic matters on the surface of clay minerals: Variations of molecular properties and components

Biomass burning (e.g., wildfire) frequently occurs globally, inevitably produces abundant biomass-burning smoke-derived dissolved organic matters (BBS-DOMs) which eventually deposits on the surface environment. The adsorption and fractionation of BBS-DOMs on clays inevitably alter their biogeochemical process and environmental behaviors in the surface environment. It is therefore important to clarify the adsorption and fractionation of BBS-DOM on clay surfaces. This study found that the fractionation of BBS-DOMs on clays (montmorillonite and kaolinite) were controlled by their functional groups, aromaticity, molecular size and organic components. The spectral indexes (SUVA254 and S275–295) of BBS-DOMs in solution after clays adsorption suggested that with the increasing DOC concentration, the primary interaction between BBS-DOMs and clays changed from hydrogen bond to hydrophobic/pore filling effects, and the adsorption ratio of the large molecules increased, which were very different from natural fulvic acid. Furthermore, various BBS-DOMs and fulvic acid had different component fractionation behaviors during clay adsorption, because they had different abundances of protein-like matters (hydrogen bond donors), pyridine-N/pyrimidine-N (positive charge doners of electrostatic interaction), and fulvic-like matters (hydrophobic interaction and pore filling effect). Additionally, the increasing pH weakened the adsorption of bulk BBS-DOMs and enhanced the adsorption ratio of aromatic matters and smaller BBS-DOM molecules. Meanwhile, at a higher pH, the adsorption ratio of protein-like matters increased, while the adsorption ratio of humic- and fulvic-like matters decreased. The result was ascribed to the enhanced hydrogen bond between protein-like matters and clays as well as the enhanced electrostatic repulsion between humic−/fulvic-like matters and clays. This study is helpful for deeply understanding the multimedia-crossing environmental behavior of BBS-DOMs in the surface environment.

Efficacy of different bioactive glass S53P4 formulations in biofilm eradication and the impact of pH and osmotic pressure

AimThe challenging properties of biofilm-associated infections and the rise of multidrug-resistant bacteria are prompting the exploration of alternative treatment options. This study investigates the efficacy of different bioactive glass (BAG) formulations - alone or combined with vancomycin - to eradicate biofilm. Further, we study the influence of BAG on pH and osmotic pressure as important factors limiting bacterial growth. MethodDifferent BAG S53P4 formulations were used for this study, including (a) powder (<45 μm), (b) granules (500–800 µm), (c) a cone-shaped scaffold and (d) two putty formulations containing granules with no powder (putty A) or with additional powder (putty B) bound together by a synthetic binder. Inert glass beads (1.0–1.3 mm) were included as control. All formulations were tested in a concentration of 1750 mg/ml in Müller-Hinton-Broth against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE). Vancomycin was tested at the minimum-inhibitory concentration for each strain. Changes in pH and osmolality over time were assessed at 0 h, 24 h, 72 h and 168 h. ResultsAll tested BAG formulations showed antibiofilm activity against MRSA and MRSE. Powder and putty B were the most effective formulations suppressing biofilm leading to its complete eradication after up to 168 h of co-incubation, followed by granules, scaffold and putty A. In general, MRSE appeared to be more susceptible to bioactive glass compared to MRSA. The addition of vancomycin had no substantial impact on biofilm eradication. We observed a positive correlation between a higher pH and higher antibiofilm activity. ConclusionsBAG S53P4 has demonstrated efficient biofilm antibiofilm activity against MRSA and MRSE, especially in powder-containing formulations, resulting in complete eradication of biofilm. Our data indicate neither remarkable increase nor decrease in antimicrobial efficacy with addition of vancomycin. Moreover, high pH appears to have a direct antimicrobial impact; the role of high osmolality needs further investigation.