Concentration Of Free Radicals Research Articles

Unraveling the mechanisms of free radicals-based transformation and accumulation of potentially toxic metal(loid)s in biochar- and compost-amended soil-plant systems

Rapid industrialization and urbanization have resulted in the widespread contamination of soil by potentially toxic metal(loid)s (PTMs). Among these, arsenic (As), cadmium (Cd), chromium (Cr) lead (Pb) and nickel (Ni) are particularly concerning, affecting millions of hectares of arable land globally and posing significant threats to food security and human health. Biochar (BC) has emerged as a promising soil amendment due to its ability to mitigate soil pollution by immobilizing contaminants. But how biochar-linked free radicals affect this process in plants and soil remains murky. Additionally, the mechanism of the geochemical transformation of PTMs in soil-plant systems influenced by biochar-based free radicals is unclear. Here, the influence of free radicals on immobilization, and transformation of PTMs in the soil-plant system under various BC and Comp treatment was investigated. Six treatment groups (1% and 2% biochar, compost, combined application, and control) were randomly assigned to pots in a randomized complete block design (RCBD) to test their effects on maize growth. Results revealed that there was a noticeable rise in the concentration of free radicals in both the BC and Comp treatments compared to the control and the combined application of BC and Comp treatments. The biochar treatment showed a slight reduction in these functional groups, suggesting possible adsorption or sequestration onto the BC surface while the Comp treatment led to an increase in functional groups associated with carbohydrates, proteins, and lipids, indicating enhanced organic matter content. The combined treatment exhibited intermediate effects, suggesting a synergistic interaction between Comp and biochar. X-ray diffraction analysis indicated that the BC did not demonstrate significant alterations in soil mineralogy, suggesting minimal direct effects on mineral dissolution or transformation. Conclusively, biochar-generated free radicals, especially hydroxyl radicals (•OH), play a crucial role in PTMs (i.e., Cd, Cr, Ni, As and Pb) immobilization in soil-plant systems. This study provides novel insights into biochar's mechanisms for mitigating PTMs pollution, paving the way for optimized soil amendment strategies.

Tracing the antioxidant effect of vitamin E on ultra-high molecular weight polyethylene

The antioxidant effect of vitamin E on ultra-high molecular weight polyethylene (UHMWPE) during radiation oxidation and post-irradiation oxidation process was investigated using electron paramagnetic resonance spectroscopy (EPR) and fourier transform infrared microscopy (FTIR). EPR results showed that the free radical concentration of UHMWPE induced by γ-rays irradiation decreased with increasing vitamin E content both in air and nitrogen atmosphere. FTIR results indicated that the irradiated samples underwent a continuous oxidation reaction, and the higher the vitamin E content, the lower the oxidation reaction. However, radiation oxidation also occurred inevitably to the vitamin E-stabilized UHMWPE indicating vitamin E could only partially prevent oxidation. Further investigation suggested that ozone can rapidly oxidize the vitamin E-stabilized UHMWPE, that is, vitamin E cannot prevent ozone from oxidizing UHMWPE. Then radiation oxidation schematic presentation of vitamin E-stabilized UHMWPE was described. This work would provide more comprehensive understanding on the radiation oxidation and post-irradiation oxidation of vitamin E-stabilized UHMWPE.

Quenching residual H2O2 from UV/H2O2 with granular activated carbon: A significant impact of bicarbonate

UV/H2O2 has been used as an advanced oxidation process to remove organic micropollutants from drinking water. It is essential to quench residual H2O2 to prevent increased chlorine demand during chlorination/chloramination and within distribution systems. Granular activated carbon (GAC) filter can quench the residual oxidant and eliminate some of the dissolved organic matter. However, knowledge on the kinetics and governing factors of GAC quenching of residual H2O2 from UV/H2O2 and the mechanism underlying the enhancement of the process by HCO3− is limited. Therefore, this study aimed to analyse the kinetics and influential factors, particularly the significant impact of bicarbonate (HCO3−). H2O2 decomposition by GAC followed first-order kinetics, and the rate constants normalised by the GAC dosage (kn) were steady (1.6 × 10−3 L g−1 min−1) with variations in the GAC dosage and initial H2O2 concentration. Alkaline conditions favour H2O2 quenching. The content of basic groups exhibited a stronger correlation with the efficiency of GAC in quenching H₂O₂ than did the acidic groups， with their specific kn values being 8.9 and 2.4 min−1 M−1, respectively. The presence of chloride, sulfate, nitrate, and dissolved organic matter inhibited H2O2 quenching, while HCO3− promoted it. The interfacial hydroxyl radical (HO•) zones were visualised on the GAC surface, and HCO3− addition increased the HO• concentration. HCO3− increased the concentration of persistent free radicals (PFRs) on the GAC surface, which mainly contributed to HO• generation. A significant enhancement of HCO3− on H2O2 quenching by GAC was also verified in real water. This study revealed the synergistic mechanism of HCO3− and GAC on H2O2 quenching and presents the potential applications of residual H2O2 in the H2O2-based oxidation processes.

Free radicals trigger the closure of open pores in lignin-derived hard carbons toward improved sodium-storage capacity

The chemical activation of various precursors is effective for creating additional closed pores in hard carbons for sodium storage. However, the formation mechanism of closed pores under the influence of pore-forming agents is not well understood. Herein, an effective chemical activation followed by a high-temperature self-healing strategy is employed to generate interconnected closed pores in lignin-derived hard carbon (HCs). By systematic experimental design combined with electron paramagnetic resonance spectroscopy, it can be found that the content of free radicals in the carbon matrix influences the closure of open pores at high temperatures. Excessively high activation temperature (>700 °C) leads to a low free radical concentration, making it difficult to achieve self-healing of open pores at high temperatures. By activation at 700 °C, a balance between pore making and self-healing is achieved in the final hard carbon. A large number of free radicals triggers rapid growth and aggregation of carbon microcrystals, blocking pre-formed open micropores and creating additional interconnected closed pores in as-obtained hard carbons. As a result, the optimized carbon anode (LK-700-1300) delivers a high reversible capacity of 330.8 mA h g−1 at 0.03 A g−1, which is an increase of 86 mA h g−1 compared to the pristine lignin-derived carbon anode (L-700-1300), and exhibits a good rate performance (202.1 mA h g−1 at 1 A g−1). This work provides a universal and effective guidance for tuning closed pores of hard carbons from other precursors.

Tailoring Bandgap and Photocatalytic Performance of Designed Zinc Oxide Platelets by Cobalt Doping

AbstractPlatelet‐shaped zinc oxide (ZnO) particles exhibit certain advantages compared to conventional micron and nano forms. Their superior surface coverage and excellent optical properties make these particles very attractive as UV filters in cosmetics and personal care applications. Although ZnO is non‐toxic, it exhibits photocatalytic activity (PCA), which increases when the size of particles approaches the nanoscale. High PCA of mineral/inorganic filters is not desired in cosmetics and personal care applications. Therefore, it is essential to develop strategies to reduce PCA of such materials under UV exposure. Accordingly, the research objective of this study is to develop an understanding of the effects of Co‐doping on the optoelectronic and crystal structure of platelet shaped ZnO particles with Zn1‐xMxO stoichiometry (x=0‐4 wt % cobalt). XRD‐based Rietveld refinement and WD‐XRF reveal that Co was successfully doped into the ZnO lattice. SEM and particle size analyses confirmed that the shape and size of the designed ZnO platelets did not change significantly after doping. ~85 % reduction in PCA has was achieved by 3 wt % Co doping which was attributed to reduced OH and O2 free radical concentration. These results clearly show that Co‐doping can be used to effectively tailor the bandgap and optical properties of the designed ZnO particles.

Transcriptional analysis of oxidative and nitrosative stress on oral opportunistic Candida albicans.

The yeast Candida albicans is one of the most aggressive opportunistic pathogens in immunocompromised patients. The ability of the yeast to withstand stresses and radicals is of great concern. In the present study, four isolates of C. albicans were taken from patients with oral candidiasis and grown on RPMI for 24 hours at 37°C. Then, they were exposed to various concentrations of oxidative (H2O2) and nitrosative (HNO3) stress for two hours, and gene expression rates were measured through RT-PCR. After initial biofilm formation steps and growth validation, RNA extracted from the yeast and gene expression status were evaluated. Upon treatment with H2O2, the gene expression profile for ALS1, MLH1, and EXO1 showed approximately a fold increase in expression. While within HNO3 the yeast gene expression exhibited a dramatic increase in ALS1 up to 217 folds, while others such as MLH1, HWP1, and ERG11 showed a one-fold increase in the expression rate. The findings of this research indicate a considerable expression activity within the biofilm of Candida albicans, increased rate of DNA mismatch repair and break fixation may indicate the ability of the yeast to tolerate high concentrations of free radicals. It paves the way toward understanding the pathogenicity of the yeast and its survival capability inside macrophages. The study also revealed that the biofilm strategy of the yeast is more active within these stresses.

Antiradical capacity assay for hydrophobic substances using hemin-catalyzed luminol chemiluminescence in cationic micelles.

Antioxidant substances which can diminish the steady-state concentration of free radicals invivo are important in the human dietary to diminish the deleterious effects of oxidative stress. As the potential of certain substances as antioxidants is difficult to be verified invivo, simple chemical invitro assays which test the potential of substances as antioxidants are of great importance for the screening of new antioxidants. These assays measure the capacity of a substance to suppress free radicals. We describe here an antiradical capacity assay, based on luminol chemiluminescence, in cationic micellar medium, allowing the capacity determination of hydrophobic compounds. The antiradical capacity of antioxidants is determined using the Trolox standard by the measurement of the light emission inhibition area caused by the addition of different antiradical concentrations. The obtained results are compared to the values determined using the scavenging of stable free radicals be the substances and shown to be similar for compounds like uric acid, rutin, and quercetin. However, for vitamin E, the luminol assay results in a considerably higher antiradical capacity than the assay with a stable free radical, which is rationalized by the higher reactivity of the radical generated in the luminol assay and a specific localization of vitamin E in the micellar medium.

Application of electron paramagnetic resonance spectroscopy to examine free radicals formed in indapamide and torasemide storage under UV irradiation and at the higher temperatures which appear under light exposition

Free radical formation in two diuretics: indapamide and torasemide was examined during UV irradiation and storage at higher temperatures using X-band (9.3 GHz) electron paramagnetic resonance spectroscopy (EPR). The aim of this study was to investigate the possibility of storing indapamide and torasemide under UV irradiation and at higher temperatures, which may occur during exposure to light. The diuretic samples were exposed to UVA irradiation for 15, 30 and 45 minutes, and stored at temperatures of 40 °C and 50 °C by 30 minutes. The EPR spectra were analyzed to determine the amplitudes (A), linewidths (ΔBpp), and integral intensities (I) and g factors. The concentrations of free radical (N) in the diuretic samples were also determined. The influence of microwave power on amplitudes, linewidths and the asymmetry parameter were evaluated. The result showed that the tested indapamide and torasemide samples exhibited high free radical concentrations in the range of 1018-1019 spin/g after UV irradiation and heat treatment. Therefore, due to the significant free radical formation indapamide and torasemide should not be stored under UV light and at temperatures of 40 °C and 50 °C. The complex character of free radical systems in the diuretic samples was proved as evidenced by the changes of the asymmetry parameters of the EPR lines with increasing microwave power. Fast spin-lattice relaxation processes were observed in all tested diuretic samples, regardless of the storage conditions. Electron paramagnetic resonance spectroscopy is proposed as a useful method in pharmacy to determine the appropriate storage conditions for diuretics.

Experimental and simulation study of inert gas mixture inhibiting coal spontaneous combustion

To explore the mechanism of inhibiting spontaneous combustion of coal by mixed gases, the low-temperature oxidation characteristics of coal under different components of mixed gases were analyzed. ESR and FTIR experiments were used to investigate the effects of different gas mixtures on the activity of coal during low-temperature oxidation and the oxidation reaction of coal surface functional groups. The mechanism of chemical oxygen inhibition of mixed gas was studied by density functional theory. The results show that the larger the CO2 component in the mixed gas, the higher the ability to inhibit coal oxidation. The concentration of free radicals in coal under dry air condition is higher than that under inert mixed gas condition during oxidation heating at 30–230 °C. The oxidation ability of –CH3, –OH and oxygen-containing functional groups in the mixed gas reaction is inhibited. Through quantum chemistry calculation, it is found that the mixed gas increases the activation energy of free radicals and reduces the heat release of the reaction. This study provides theoretical reference for coal mine thermal disaster.

Biosynthesis of Silver Nanoparticles From Marine Actinobacterium Micromonospora sp. and Their Bioactive Potential.

Background The biosynthesis of nanoparticles represents a rapid, environmentally friendly, cost-effective, and straightforward technology. This approach allows for the production of nanoparticles with a wide range of chemical compositions, sizes, shapes, high uniformity, and scalability. One of the principal advantages of biogenic nanoparticles is their water solubility and compatibility with biological systems. Biologically synthesized nanoparticles have demonstrated superior efficiency compared to conventionally synthesized particles. Among biosynthesis, microbial-mediated biosynthesis is a promising one that has a selectively reducing ability on specific metal ions through electron transfer. Objectives Evaluation of antimicrobial and antioxidant activity of silver nanoparticle synthesized by actinobacteria Micromonospora sp. which is isolated from marine environment. Materials and methods In this study, actinobacteria were isolated from the marine sediment using the spread plate method. The isolates were identified based on morphological observation, cell wall amino acids, sugar analysis, and micromorphological analysis. The silver nanoparticle synthesis from microbes and their inhibition against clinical pathogens have been evaluated by the disc diffusion method.Antioxidant efficiency was evaluated in termsof total antioxidant activity through ammonium molybdenum assay. Results A total of five isolates were isolated from the sediment sample. The cell-free extract of MBIT-MSA4 can synthesize silver nanoparticles that have potential antimicrobial activity against the clinical pathogens Streptococcus mutans at a zone of inhibition 6 mm, 10 mm inhibition zone of Klebsiella pneumonia,and 8 mm zone of inhibition of Staphylococcus aureus. Also, it has significant antioxidant activity up to 73% of free radical inhibition. Conclusion Marine microbial-mediated biosynthesized silver nanoparticles have potential antimicrobial activity against S.mutansand methicillin-resistantStaphylococcus aureus(MRSA) and inhibit the oxidation process through antioxidant activity. Thisenhanced efficient biosynthesisednanoparticle has significantly reduced the concentration of free radicals caused by pathogens.

Study on the inhibition effect and mechanism of N2 twin-fluid water mist with modified chloride compounds on LPG explosion

In order to develop environmontal friendly and high efficient LPG explosion inhibitors, experiments were carried out to investigate the impact of AeO9 (fatty alcohol polyoxyethylene ether) and Sicare2235 (silicone surfactant) surfactants on the suppression effect of N2 twin-fluid water mist containing modified chloride compounds on 6 % LPG/air explosion. Results showed that: The addition of a single surfactant can significantly reduce the surface tension of the droplets and improve the explosion suppression efficiency of N2 twin-fluid water mist containing chloride additives. However, chloride additives have selectivity towards surfactants. There are obvious differences in the synergistic inhibition effect of different chlorides and surfactants. Under the combination of 0.6 % AeO9, 0.06 % Sicare2235 surfactants and chloride additives, the increase in surface tension will weaken the physical explosion suppression effect and lead to the phenomenon of explosion enhancement. The results of chemical kinetics simulations indicate that, in comparison to a single explosion suppressant, the chlorine-containing compound N2 twin-fluid water mist effectively lowers the adiabatic flame temperature and the concentration of key free radicals H, OH and O. The reaction CH3 + H + M = CH3OH + M plays a pivotal role in reducing the adiabatic flame temperature during LPG explosion.

Role of moisture content in coal oxidation during the spontaneous combustion latency

The role of moisture content in coal oxidation during the spontaneous combustion latency was studied by an isothermal flow reactor. The physical and chemical changes during the drying and oxidation process were investigated using low-pressure nitrogen gas adsorption (LP-N2GA) experiments, Electron spin resonance (ESR) experiments and X-ray photoelectron spectroscopy (XPS) experiments. Experimental results reveal that moisture acts either as a promoting or an inhibiting agent under different contents. The differences in total temperature rise (TTR) of varying coal samples are the result of a complex set of competing factors. The LP-N2GA experiments reveal no pore collapse until the moisture reaches 3.05 %. Collapse clearly occurs with the micropore and mesoporous size range. When the moisture content is higher 3.05 %, the specific surface and pore volume increases with the removal of moisture. In addition, the evaporation of water also re-exposes the previously covered active sites and increases the concentration of free radicals. However, the removal of moisture makes the generation of peroxides more difficult due to moisture acts as a catalyst in the formation of such peroxide species.

Synergistic mechanisms between chlorine-mediated electrochemical advanced oxidation and ultraviolet light for ammonia removal

The combination of chlorine-mediated electrochemical advanced oxidation (Cl-EAO) and ultraviolet (UV) radiation (UV-E/Cl) can efficiently remove ammonia from wastewater. However, the synergistic mechanisms between Cl-EAO and UV need to be explored in more detail. Thus, in this study, the ammonia oxidation performance of Cl-EAO and UV-E/Cl systems were compared, while the synergistic mechanisms were identified by the performance of UV/chlorine oxidation (UV–ClO) system and the results of electron paramagnetic resonance (EPR) analysis, free radical inhibition assays, and determination of steady-state concentration of free radicals. It was found that, compared with the Cl-EAO system, UV increased the ammonia removal rate by 42.85% and reduced the active chlorine concentration (56.64%) and nitrate yield (53.61%). In the Cl-EAO, and UV-E/Cl systems, Cl• were detected, and the free radical inhibition assays and determination of steady-state concentration of free radicals suggested that UV increased the concentration of Cl• by 51.47%, resulting in Cl• becoming the major contributor to ammonia oxidation in the UV-E/Cl system. Besides, UV also increase the concentrations of HO• and Cl2•-, which further promoted the organic matter removal in the real domestic wastewater. This study also discussed the ammonia oxidation performance of the UV-E/Cl system in real domestic wastewater, even with the presence of significant levels of organic and inorganic anions in the wastewater, UV increased the ammonia oxidation by 21.95%. The results of this study thus clarify the mechanisms and potential applications of UV-E/Cl technology.

Efficient Photochemical Vapor Generation from Low Concentration Formic Acid Media.

Herein, we report on surprisingly efficient photochemical vapor generation (PVG) of Ru, Re, and especially Ir, achieved from very dilute HCOOH media employing a thin-film flow-through photoreactor operated in flow injection mode. In the absence of added metal ion sensitizers, efficiencies near 20% for Ir and approximately 0.06% for Ru and Re occur in a narrow range of HCOOH concentrations (around 0.01 M), significantly higher than previously reported from conventionally optimized HCOOH concentrations (1-20 M). A substantial enhancement in efficiency, to around 9 and 1.5%, could be realized for Ru and Re, respectively, when 0.005 M HCOONa served as the PVG medium. The addition of metal ion sensitizers (particularly Cd2+ and Co2+) to 0.01 M HCOOH significantly enhanced PVG efficiencies to 17, 2.2, and 81% for Ru, Re, and Ir, respectively. Possible mechanistic aspects occurring in dilute HCOOH media are discussed, wherein this phenomenon is attributed to the action of 185 nm radiation available in the thin-film flow-through photoreactor. An extended study of PVG of Fe, Co, Ni, As, Se, Mo, Rh, Te, W, and Bi from both dilute HCOOH and CH3COOH was undertaken, and several elements for which a similar phenomenon appears were identified (i.e., Co, As, Se, Te, and Bi). Although use of dilute HCOOH media is attractive for practical analytical applications employing PVG, it is less tolerant toward dissolved gases and interferents in the liquid phase due to the likely lower concentrations of free radicals and aquated electrons required for analyte ion reduction and product synthesis.

Evaluation of the functional properties of ethanolic and polysaccharide extracts of Spirulinaplatensis

This study aimed to investigate the prebiotic, antioxidant and antimicrobial activity of ethanolic and polysaccharide extracts from Spirulina platensis. The ethanol extract was obtained by the soxhlet method and the polysaccharide was extracted with hot water. Total phenol content was obtained by the folin-ciocalteu method. The ethanol extract and the polysaccharide extracted from the S. platensis had a high phenol. Also, the extract had comparable prebiotic properties with commercial prebiotic (Inulin). Both extracts in the period of 24–72 h affected the growth and viability of the Lactobacillus plantarum A7. Based on the results, the half-maximal inhibitory concentration (IC50) of DPPH free radical for ethanol extract and polysaccharide was estimated to be 0.279 and 0.319 mg/mL. Also, the IC50 of hydroxyl radical scavenging capacity for polysaccharide and ethanol extract was calculated to be 0.167, 0.14 mg/mL, respectively. Therefore, these compounds can be introduced as natural substances with antioxidant, prebiotic and antimicrobial capabilities in the food and pharmaceutical industries.

Citric acid–enhanced Fe2+ and Cu2+ synergistic activation of persulfate for rhodamine B degradation

Citric acid (CA) and Cu2+ were used to enhance Fe2+-activated persulfate (PDS) for rhodamine B (RhB) oxidative degradation. The effects of PDS concentration, Fe2+ concentration, CA concentration, Cu2+ concentration, pH, and common inorganic anions in water on PDS activation and RhB degradation were investigated. Results showed that sulfate and hydroxyl radicals were the primary active substances in the reaction system, with sulfate radical playing a key role. The addition of CA and Cu2+ improved the efficiency of RhB decomposition, achieving a removal rate of 98.4% after 30 min of reaction, governed by pseudo-first-order. The presence of a complexing agent, allows effective RhB removal over a wide pH range. The free sulfate radical (SO4·−) concentration increases with increasing Fe2+ concentration. However, when the Fe2+ concentration was higher than 0.5 mM, self-quenching of SO4·− occurred and the RhB degradation rate decreased. In contrast, with increasing PDS concentration, the degradation rate of RhB continued to increase. The radical process was the main mechanism of RhB decomposition. Analysis of intermediates showed that C–C and C–N bond cleavage was the most likely degradation mode for contaminants to become small molecules.

Arsenic removal from coal by ferric chloride enhanced leaching under ultraviolet irradiation during flue gas desulphurization with coal slurry

ABSTRACT During coal combustion, the harmful element arsenic can be released into environment and cause potential significant harm to human beings. Therefore, it is very important to study the removal of arsenic from coal before combustion. In this work, simulated SO2-containing flue gas was used to leach arsenic from coal in a 1 L UV photoreactor. The effects of FeCl3, ultraviolet (UV), pH and the Cl−/Fe3+ molar ratio on arsenic leaching and SO2 removal were experimentally investigated and the enhancing mechanism was analysed. Experimental results demonstrated that FeCl3 and UV could efficiently increase iron and arsenic leaching percentages and SO2 removal efficiency. UV irradiation could induce the oxidation of most trivalent arsenic. The arsenic leaching percentage was significantly larger than that of iron. Low pH was favourable for iron and arsenic leaching. The optimal Cl−/Fe3+ molar ratio was determined to be 3:1. The introduced ferric chloride could not only increase the concentrations of free radicals and ferric iron oxidants, the chloride ion might also impede the formation of passive coatings, thus increasing the arsenic leaching percentage, intensifying the oxidation of trivalent arsenic and enhancing the removal of SO2.

Photophysical and photodynamic analysis of different formulations of riboflavin

Background: Riboflavin (Rb) has been used in the ophthalmological procedure known as corneal cross-linking (CXL). Pathologies requiring this treatment include keratoconus, corneal ectasia, and infectious keratitis. Rb is instilled via different molecules that are transported into the tissues. However, each vehicle imparts different properties that alter the photodynamic behavior of Rb, leading to variable concentrations of free radicals within the medium. The objective of this study was to measure the concentrations of free radicals produced by commonly used Rb formulations. To determine the free radical production level of each formulation, L-tryptophan (L-Tryp) was used as a model substrate because it can be efficiently photo-oxidized.
 Methods: We investigated the photodegradation of L-Tryp and its kinetics upon light exposure. The spectra were recorded using a Shimadzu UV-1800 PC spectrophotometer and a Cary Eclipse fluorescence spectrophotometer. A high-power solid-state LED light source was used for irradiation. L-Tryp degradation was performed using a 9-W LED lamp, and steady-state photolysis was conducted in quartz cells. The observed rate constants for L-Tryp degradation were determined by analyzing the changes in absorbance and fluorescence intensity. Data analysis was performed using Origin software.
 Results: We examined the characteristics of the photophysical and photodynamic action of the carriers in different commercially available Rb formulations. These included a) Rb with dextran, b) Rb without dextran, c) VibeX Rapid® (hydroxypropylmethylcellulose as a vehicle), d) Trans-Epithelial Kit (I) (sodium chloride as a vehicle), and e) Trans-Epithelial Kit (II) (benzalkonium chloride as a vehicle), using L-Tryp as a model substrate, and focusing on absorption and emission spectra. VibeX Rapid® exhibited the highest photo-degradation constant. The study affirmed the stability of Rb formulations for CXL and highlighted the efficacy of VibeX Rapid® in L-Tryp photo-oxidation and this rationalizes its current use as a CXL agent.
 Conclusions: We demonstrated that formulations for transport of Rb are of crucial importance in CXL applications. Rb in the VibeX Rapid® formulation is more effective in generating photo-degradation, and this reflects its superior performance in CXL. Future experiments should be designed and conducted to quantitatively differentiate the production of free radicals. Studies involving human participants could shed light on the clinical efficacy and safety of the available Rb formulations.

Effect of AES anionic surfactant on the microstructure and wettability of coal

The paper object is high-quality Shenmu bituminous coal modified by fatty alcohol polyoxyethylene ether sodium sulfate (AES) surfactant. The changes in functional groups, free radicals, Zeta potential, and contact angle of coal modified in AES anionic surfactant were analyzed. Based on the molecular structure of Shenmu coal, a coal-AES-water three-phase dynamic model was constructed. The wetting mechanism of coal was studied by molecular dynamics. The research has demonstrated that as the mass fraction of AES surfactant increases, the proportion of polar groups (-OH, C–O–C, –COOH, –CO), free radical content and Zeta potential increased significantly. The size of contact angle displayed a major negative linear correlation with the proportion of polar groups and free radicals, but positively linearly correlated with the Zeta potential. In the coal-AES-water three-phase dynamic model, the AES molecules adhere to coal molecules as hydrophobic group, while hydrophilic groups extended into the water. This increased H2O diffusion coefficient, enhanced action energy between coal and water interface, decreasing surface tension and achieving effective wetting of the coal. This paper supplies s a new idea for selecting efficient surfactants to change the coal microstructure. It is of major importance for improving coal wettability and offers a theoretical foundation for gas drainage and disaster prevention.

Study on inhibiting effects of melamine polyphosphate on pulverized coal explosion: Investigation from macro and micro perspectives

Unintended release of pulverized coal could lead to an explosion, resulting in significant losses for employees and companies. It is crucial to research explosion prevention for related enterprises. The pulverized coal explosion inhibition was conducted by investigating explosion characteristic parameters, thermal analysis, and microscopic characteristics from macro and micro perspectives. The findings suggested that pulverized coal explosion could be effectively inhibited by melamine polyphosphate (MPP) powder at a ratio of 30 %. Specifically, when the concentration of pulverized coal was 300 g/m3, the optimal inhibiting concentration of MPP powder was 78.3 g/m3. Explosion pressure was positively correlated with heat release during the explosion process. As the concentration of MPP powder increased, both combustion rate and heat release gradually decreased, leading to a reduction in explosion pressure. Pulverized coal explosion led to a significant consumption of active free radicals. However, when MPP was added, free radicals concentration in products gradually increased and approached the original level. Physical inhibition was achieved by absorbing heat and diluting the mixture with inert substances. Chemical suppression mainly occurred through the consumption of key oxygen radicals by phosphorus-based compounds. The findings of this work introduce a novel concept for utilizing MPP powder as a suppressant and offers a fundamental experiment for pulverized coal explosion suppression technology.