Concentration Of Free Radicals Research Articles

Response of Rapeseed (Brassica napus L.) to Silver and Gold Nanoparticles as a Function of Concentration and Length of Exposure

There is a growing demand for high quality and sustainable food in the world and this need falls within the context of the European Green Deal’s strategy “From Farm to Fork”. In order to achieve these outcomes, the use of modern and innovative technologies of plant production and protection is required. The use of nanoparticles (NPs) in agriculture and horticulture is an example of such technology. However, research on the effect of length of exposure to metal nanoparticles on seeds germination and seedlings development are limited in the literature. In our study, the effect of silver (AgNPs) and gold nanoparticles (AuNPs) on the seedling growth and biochemical response of rapeseed after 7, 14 and 21 days was analyzed. In the experiments, 0, 50 and 100 ppm concentrations of NPs were used in vitro. The level of photosynthetic pigments, anthocyanins as well as other stress parameters, such as free phenolic compounds, free sugars or H2O2, decreased due to the application of both AgNPs and AuNPs at the initial culture period; however, the differences were observed in the successive weeks of exposure. The parameters were increasing, irrespective of the kind of nanoparticles; however, as for the content of free sugars and free radicals, higher values were recorded due to the effect of AuNPs. Our results showed that length of plants exposure to NPs is very important factor modifying growth and final response of seedlings. Better understanding of its influence could speed up use of NPs in agriculture and horticulture for production of high-quality plant material (e.g., to seed priming, stimulation of seedlings’ growth and their protection), not contaminated with pesticides, fertilizers and mycotoxins.

Characterization of Humic Substances from Taiga and Tundra Soils by EPR Spectroscopy

Paramagnetic activity is a fundamental property of humic substances (HSs). The agricultural use of soils does not only affect the qualitative and quantitative compositions of HSs, but also the content of free radicals (FRs) in their structure. Changes in the composition of incoming plant residues and hydrothermal conditions have an effect on soil humification rates and the paramagnetic properties of humic (HAs) and fulvic acids (FAs). Data on the influence of various factors on the content of FRs in HAs and FAs are not enough. Therefore, the purpose of this study was to examine the influence of the degree of hydromorphism and agricultural use on the paramagnetic properties of HA and FA samples obtained from taiga and tundra soils. Studies have shown that the increased hydromorphism in taiga soils leads to the growing concentration of FRs in the HA molecular structure. HAs in virgin tundra soils exhibit a lower content of unpaired electrons when shifting from automorphic soils to hydromorphic ones. Going from the south to the north, the paramagnetic activity of both HAs and FAs tends to decrease due to the overall reduction of the number of polyconjugated systems in the tundra soil HSs. The comparative analysis of the paramagnetic properties in HAs and FAs of virgin and arable soils revealed that their agricultural use reduces the FR concentration in the structure of HSs, in other words it leads to the accumulation of biothermodynamically stable and more humified compounds in the arable horizons. This contributes to the stabilization of SOM in arable soils.

High-intensity ultrasound improved the physicochemical and gelling properties of Litopenaeus vannamei myofibrillar protein

The effects of high-intensity ultrasound on the physicochemical and gelling properties of Litopenaeus vannamei (L. vannamei) myofibrillar protein (MP) were investigated. MP solutions were subjected to ultrasound treatment (power 100 W, 300 W, and 500 W). It was found that the carbonyl and free amino contents of MP increased significantly with increasing ultrasound power, accompanied by enhanced emulsification properties. The increase of free radical and carbonyl content indicated that ultrasound induced the oxidation of MP. With the increase of ultrasound power, it was found that the total sulfhydryl content of the shrimp MP decreased, but the surface hydrophobicity increased significantly, which might be closely related to the conformational changes of MP. Meanwhile, a significant increase of β-sheet but a decrease of α-helix in the secondary structure of MP was observed with increasing ultrasound power, indicating that ultrasound treatment induced the stretching and flexibility of MP molecules. SDS-PAGE showed that L. vannamei MP consisted of myosin heavy chain, actin, myosin light chain, paramyosin and tropomyosin. Ultrasound treatment could lead to some degree of oxidative aggregation of MP. The results of rheological properties indicated that ultrasound treatment enhanced the viscoelasticity of MP and further improved the gel strength of MP gel. This study can provide a theoretical basis for the functional modification of shrimp MP and the processing of its surimi products.

Effects of mechanical activation atmosphere on the co-liquefaction of Xigou coal and petroleum vacuum residue

The effects of mechanical activation (MA) atmosphere on the co-liquefaction of Xigou coal and Karamay petroleum vacuum residues were investigated. MA induces a smaller particle size of coal powders, which are more easily dissolved in wash oil during co-liquefaction. FT-IR and 13C NMR data of coal samples show that MA can partially break alkyl side chains. Especially, it is easier for MA under hydrogen and air atmosphere to shorten or break alkyl side chains and bridged bonds compared to vacuum and nitrogen atmosphere. MA enhances pyrolysis reaction activity of coal samples through decreasing the apparent activation energy, which is conductive for co-liquefaction. For MA with hydrogen atmosphere, the highest conversion rate and oil yield of co-liquefaction are obtained, which are 98.2% and 84.4%, respectively, followed by air atmosphere. More distillate oil and heavy oil are produced from co-liquefaction with MA under hydrogen atmosphere, but fewer gaseous products. There are 9.7% petrol generated from co-liquefaction with MA under air atmosphere, which are higher than that from other atmospheres. MA partially destroys the physicochemical structure of coal and increases the concentration of free radicals because of the energy generated by collision and friction, thereby enhancing the reactivity in co-liquefaction.

Antioxidant Test of Red and Green Colored-Leaves Infusions of Pucuk Merah (Syzygium myrtifolium Walp.) with DPPH method

Red and green leaves of the pucuk merah (Syzygium myrtifolium Walp.) contain flavonoids, saponins, and tannins which have the potential as antioxidants. The purpose is test out the antioxidant activity of red leaves and green leaves infusions of red shoots (S. myrtifolium). Test material is extracted using infusion method. The testing of antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The free radical concentration of DPPH was analyzed using UV-Vis spectrophotometer after addition of various concentrations of S. myrtifolium leaves infusion extracts. Various concentrations of S. myrtafolium leaves infusion extracts used were 20 ppm; 10 ppm; 5 ppm; 2.5 ppm; 1.25 ppm; 0.625 ppm. Vitamin C solutions as the positive control were prepared on 5; 2.5; 1.25; 0,625; 0.3125 ppm. The result of the experiment showed the thick red and green leaf extract has IC50 value of 11,130 ppm and 10,522 ppm. The antioxidant activity of green leaf extract is higher than the red leaf extract. Research on green leaves extract of S. myrtafolium is suggested for further research as anticancer.

MRI of radiation chemistry: First images and investigation of potential mechanisms.

Paramagnetic species such as O2 and free radicals can enhance T1 and T2 relaxation times. If the change in relaxation time is sufficiently large, the contrast will be generated in magnetic resonance images. Since radiation is known to be capable of altering the concentration of O2 and free radicals during water radiolysis, it may be possible for radiation to induce MR signal change. We present the first reported instance of x-ray-induced MR signal changes in water phantoms and investigate potential paramagnetic relaxation enhancement mechanisms associated with radiation chemistry changes in oxygen and free radical concentrations. Images of water and 10 mM coumarin phantoms were acquired on a 0.35 T MR-linac before, during, and after a dose delivery of 80Gy using an inversion-recovery dual-echo sequence with water nullified. Radiation chemistry simulations of these conditions were performed to calculate changes in oxygen and free radical concentrations. Published relaxivity values were then applied to calculate the resulting T1 change, and analytical MR signal equations were used to calculate the associated signal change. Compared to pre-irradiation reference images, water phantom images taken during and after irradiation showed little to no change, while coumarin phantom images showed a small signal loss in the irradiated region with a contrast-to-noise ratio (CNR) of 1.0-2.5. Radiation chemistry simulations found oxygen depletion of -11µM in water and -31µM in coumarin, resulting in a T1 lengthening of 24ms and 68ms respectively, and a simulated CNR of 1.0 and 2.8 respectively. This change was consistent with observations in both direction and magnitude. Steady-state superoxide, hydroxyl, hydroperoxyl, and hydrogen radical concentrations were found to contribute less than 1ms of T1 change. Observed radiation-induced MR signal changes were dominated by an oxygen depletion mechanism. Free radicals were concluded to play a minor secondary role under steady-state conditions. Future applications may include in vivo FLASH treatment verification but would require an MR sequence with a better signal-to-noise ratio and higher temporal resolution than the one used in this study.

Antioxidant Potential of Resveratrol as the Result of Radiation Exposition.

The purpose of this study was to determine the effect of electron beam irradiation (EBI) at a dose of 25 kGy on the stability and antioxidant properties of resveratrol (RSV), a nutraceutical with clinically proven activity. The electron paramagnetic resonance (EPR) method was used to evaluate the concentration of free radicals after irradiation. Minor changes in chemical structure due to free radicals induced by EBI were confirmed by FTIR spectroscopy. HPLC and HPLC-MS analysis ruled out the appearance of degradation products after irradiation. In addition, HPLC analysis confirmed the absence of trans- to cis-resveratrol conversion. Changes in the antioxidant potential of RSV after irradiation were studied using DPPH, ABTS, CUPRAC, and FRAP techniques. It was confirmed that EBI favorably affected the antioxidant properties of tests based on the HAT mechanism (increase in DPPH and CUPRAC tests).

Synergistic Inhibiting and Sealing Material for Preventing the Compound Disaster of Gas and Coal Spontaneous Combustion: Ratio Optimization and Inhibition Test

ABSTRACT The spontaneous combustion and gas explosion induced by crushed small coal pillars and the residual coal of adjacent goaf will cause a large amount of coal loss and casualties of workers. Moreover, it also seriously pollutes the environment and aggravates the greenhouse effect. To effectively block small coal pillars and fracture zones of adjacent old workings is the key to prevent gas and coal spontaneous combustion in small coal pillars. However, the commonly used blocking materials at present are easy to shrink and chap after air drying, and they have no chemical inhibitory property. Thus, these materials cannot realize the coordinated prevention of gas and coal spontaneous combustion. In this paper, a low-cost and eco-friendly Synergistic Inhibiting and Sealing Material (SISM)with strong inhibitory properties is proposed. The optimal ratio of the material was determined by experiments. The inhibitory properties of the material are analyzed by testing and comparing the generation rate of free radical and CO generation rate. The experimental results showed that the optimal molar ratio of main antioxidant and auxiliary antioxidant was 5:2, and the optimal mass ratio of synergistic antioxidant and high water material was 1:8. Secondly, SISM can prevent or delay the production of new free radicals during coal spontaneous combustion, significantly reduce the concentration of free radicals in coal and finally delay the process of coal spontaneous combustion. Thirdly, both physical and chemical inhibitory properties are taken into account when preparing SISM. Hence, it can maintain both high inhibitory properties in the whole temperature range and the inhibition effect on coal-oxygen compound reaction, which is significantly better than MgCl2 and yellow mud (YM) with only physical inhibition.

Nano-depletion of morbid spermatozoa up-regulate Ca2+ channel, depolarization of membrane potential and fertility in buffalo

Despite recent advances in technique of spermatozoa cryopreservation, there are still ejaculates present that fail to meet strict quality standard; mainly due to detrimental effect of imbalance of free radicals. The omnipresence of dead/defective spermatozoa in ejaculates of eutherian species is a major source of excessive free radicals. Though sperm-selection techniques, as well as addition of antioxidants addressed the problem to a certain extent, the major source of free radicals in the semen remained, causing much damage. This study attempts to remove dead/damaged spermatozoa using negative fertility-marker. The effect is unraveled by Hypo-osmotic (HOS), and fluorescein-conjugated Pisum sativum agglutinin (FITC-PSA) assay, further confirmed by Ca2+-regulating mechanisms and depolarization of sperm membrane potential, reduction in concentration of free radicals and finally by in vitro fertility assay. The study involved functionalization of iron oxide nanoparticles (IONPs) with silane followed by bio-conjugation with anti-ubiquitin antibodies. The nano-purification of semen using anti-ubiquitin conjugated iron oxide nanoparticles (IONPs) (antibody concentrations 0.5, 1.0 and 2.0 μg/ml) was attempted. The efficiency of nano-purification was 18.1%–43.8% in the study. The results revealed greater (P ≤ 0.05) spermatozoa population with intact plasma membrane, acrosome integrity, high mitochondrial membrane potential and pattern-F (least intracellular Ca2+), evidence of low lipid peroxidation and higher total antioxidant capacity in nano-purified groups. More number of spermatozoa were bound to zona pellucida of matured oocytes from nano-depleted than non-depleted group. The findings demonstrate antibody concentration of 1.0 μg/ml bio-conjugated with IONPs as most efficient in enriching the ejaculate with functional spermatozoa with the highest percentage of zona binding.

Molecular-based asphalt oxidation reaction mechanism and aging resistance optimization strategies based on quantum chemistry

Understanding the oxidation reaction mechanism of asphalt is critical to improving its aging resistance. Here, quantum chemistry (QC) was used to study the oxidation reaction mechanism of 12 typical asphalt molecules. On this basis, the molecular models of aged asphalt were established, and the aging resistance optimization strategies of asphalt were proposed. The results show that the oxidation sites for oxygen-containing or heteroatoms-free molecules are on aromatic carbons (I molecules). Reducing hydrogen and hydroxyl radicals can improve its aging resistance. The oxidation sites for sulfur- or nitrogen-containing molecules are on heteroatoms (II molecules). Reducing oxygen free radicals content can improve its aging resistance. The molecules containing sulfur and cata-condensed polycyclic aromatic hydrocarbons (PAHs) (such as R5) have the strongest oxidation reactivity. Reducing its content can improve asphalt aging resistance. Combining the QC and experiment results, LH90 contains more I molecules, while UP70 and MM70 contain more II molecules (especially As3 and R5). The aging resistance of UP70 and MM70 is poor than LH90. Reducing the content of As3 or R5 molecules or the content of oxygen radicals can improve the aging resistance of UP70 and MM70. These findings lay a foundation for designing and preparing asphalt with excellent aging resistance.

Mechanism of MnSOD removing peroxy radical for inhibiting coal spontaneous combustion

• The pathways of free radical small and large cyclic chain reactions were analyzed; • The disproportionation reaction of MnSOD and peroxy radical was analyzed; • The mechanism of MnSOD scavenging peroxy radical was revealed; • The effect of MnSOD inhibiting coal spontaneous combustion was verified. Superoxide dismutase (MnSOD) was proposed as an inhibitor to inhibit coal spontaneous combustion (CSC). The pathways of free radical cyclic chain reaction were analysed. The mechanism of MnSOD removing peroxy radical (–OO·) was calculated by quantum chemical method, and the effect of MnSOD inhibiting CSC was verified by electron paramagnetic resonance experiment. Results showed that –OO· is the key to triggering free radical small and large cyclic chain reactions. The Mn ion is the active site of the MnSOD. MnSOD disproportionates –OO· in four steps: firstly, –OO· undergoes an addition reaction with MnSOD, and a new coordination bond –OO attaching to the Mn ion is generated; secondly, Mn 3+ is reduced to Mn 2+ by –OO· with the –OO bond broken to release O 2 ; thirdly, Mn 2+ is oxidised to Mn 3+ by –OO·, and a new coordination bond –OOH is formed with the reaction of H + and –OO·, which is attached to the Mn ion; lastly, H 2 O 2 is formed when H + reacts with the broken –OOH bond. In the first step, only covalent bonds are formed with no bond breaking and energy barriers. The energy barriers for the second to fourth reactions are 52.51, 78.77 and 183.79 kJ/mol, and the reaction rates are 3.848 × 10 5 , 9.601 and 3.760 × 10 −18 s −1 M −1 , respectively. In this four-step reaction, the heat release values are 131.28, –78.77, 472.59 and –210 kJ/mol. The –OO· is consumed during the reduction and oxidation reactions of Mn ions to generate O 2 and H 2 O 2 , respectively. The g value of the MnSOD coal sample decreases, the line width narrows, and the free radical concentration decreases, indicating that MnSOD can effectively inhibit CSC.

Relaxometry for detecting free radical generation during Bacteria's response to antibiotics

Free radical generation plays a key role in killing bacteria by antibiotics. However, radicals are short-lived and reactive, and thus difficult to detect for the state of the art. Here we use a technique which allows optical nanoscale magnetic resonance imaging (MRI) to detect radical generation on the scale of single bacteria. We demonstrate that the radical generation in Staphylococcus aureus increases in the presence of UV irradiation as well as vancomycin and is dependent on the antibiotic's dose. With a method based on ensembles of nitrogen vacancy (NV) centers in diamond, we were able to follow the radical formation near individual bacteria over the whole duration of the experiment to reveal the dynamics of radical generation. Using this new approach, we observed free radical concentrations within nanoscale voxels around the diamond particles and determined its exact timing depending on the antibiotic dose. Since changes in the response to antibiotics emerge in only a few bacteria of the entire population, such a single-cell approach can prove highly valuable for research into drug resistance.

Effects of n-Butanol Addition on the Combustion Characteristics of n-Heptane Counterflow Diffusion Flame at Elevated Pressure

This study focused on the effects of n-butanol addition on the combustion characteristics of n-heptane counterflow diffusion flame under pressures of 1, 3, and 5 atm by a detailed kinetic simulation. The added n-butanol volume fraction ranged from 0 to 50%. The mass averaged velocity of fuel streams was selected to ensure momentum flux balance and was approximately constant for the investigated flames. Flame structures and mole fraction profiles impacted by n-butanol addition for major species, free radicals, and intermediate species were analyzed by concentrating on the formations of soot precursors and oxygenated air pollutants. The results showed that with the addition of n-butanol, the flame temperature decreased and the formation of the main soot precursors such as C2H2 and C6H6 was inhibited. This can be attributed to the reduced rate of production of these species. The flame temperature increased significantly, and the profile moved towards the fuel side with the increasing pressure. Moreover, the production of C2H2 and C6H6 was observably promoted as the pressure increased. The concentrations of free radical H, O, and OH decreased significantly as the pressure increased but slightly decreased with the increasing n-butanol addition, which might have been caused by the chemical effect of n-butanol.

BIOFILTER MANUFACTURE OF AZADIRACHTA INDICA LEAF POWDER AND ITS EFFECTIVENESS IN CAPTURING FREE RADICALS OF CIGARETTE SMOKE

Free radicals from cigarette smoke are a dangerous part that must be found to counteract. This research aims to make a composite biofilter made from Azadirachta Indica to ward off/capture free radicals from cigarette smoke. This biofilter is made with Azadirachta Indica leaf powder added to polyethylene glycol as the matrix. The biofilter was then seen for its physical characteristics; the density and porosity were tested using SEM. Furthermore, a biofilter membrane is used to filter cigarette smoke. Cigarette smoke that passes through the biofilter is then analyzed using ESR for its free radical content. The results showed that the biofilter made from Azadirachta Indica leaves could absorb several types of suspected free radicals in cigarette smoke. Biofilters using PEG as a matrix with a mass of 0.9 and 1gr were the most effective in absorbing the suspected types of free radicals. SEM test showed an average pore size of 2-3 µm for a mass of 1gr with PEG as the matrix.

Metal-Catalyzed Formation of Organic Pollutants Intermediated by Organic Free Radicals.

Metal compounds play important roles in the formation of organic pollutants during thermal-related processes. However, the metal-catalyzed predominant organic pollutants have not previously been characterized nor have any detailed catalytic mechanisms been clarified. Here, we preciously distinguished the multiple organic free radical intermediates on metal catalyst surfaces during the organic pollutant formation through laboratory and theoretical studies. Differences between the organic free radical intermediate species, concentrations, and formation mechanisms under the catalysis of different metal compounds were investigated. The results were verified mutually with the differed characteristics of organic pollutant products. CuO predominantly catalyzed the formation of highly chlorinated phenoxy radical intermediates and dioxins. High proportions of semiquinone radicals and oxygen-containing derivatives were found on ZnO surfaces. Differently, methyl-substituted phenoxy radicals and long-chain products formed on Al2O3 surfaces. The results will be instructive for the target emission control of priority organic pollutants during thermal-related processes rich in different metal compounds.

Effects of olefinic compounds on the thermal transformation for FCC slurry oil: Evolution pattern and mechanism

FCC decant oil was always used as the raw material for the preparation of high-value-added carbonaceous materials. There is little disagreement that the free radical mechanism induces thermal polymerization reactions between reactant molecules and intermediate species, which leads to the formation of carbonaceous mesophase in the early stage of carbonization. Olefinic hydrocarbons were recently found to be widely distributed in FCC decant oil in our previous research, and these chemically active compounds usually possess weak π-bonds in molecules and thus potentially form free radicals easily, which may impact the carbonization performance dramatically. This research investigated the effects of olefinic compounds on the preparation of needle coke from FCC decant oil, as well as the corresponding mechanism in depth combined with the evolution pattern of the intermediate species during liquid carbonization. ESR analyses were adopted to evaluate the variation of the concentration of stable free radicals. Stable free radical concentration varied greatly in diverse polymerizing systems along with the carbonization process. Olefin showed a significant effect on the stable free radical concentration during carbonization. The stable free radical concentration of the polymerizing system derived from FCC decant oil was 3.32 × 1020 spins/g when the reaction time was 4 h. But with 3 wt% addition of 2-vinylnaphthalene and squalene in FCC decant oil, the stable free radical concentration increased to 2.14 × 1021 spins/g and 1.33 × 1021 spins/g, respectively, with the same reaction time. Meanwhile, the olefins conjugated with aromatic rings shown more obvious effect on the generation of free radicals. Olefinic compounds can lead to a high generation rate of free radicals and significantly high stable free radical concentration in the polymerizing system which then promote the formation of disordered carbon materials. Besides, plenty of fine particles appeared between mesophase spheres with the addition of olefinic hydrocarbons, and then impeded the coalescence between mesophase spheres. Effect mechanism for olefin on the development of carbonaceous mesophase was proposed accordingly. In sum, the content of olefinic compounds in raw materials should be limited for reaching the requirements of the synthesis of carbon materials with superior structures, in which the content of olefinic compounds should be less than 1 wt% at least based on the research in this paper.

Experimental study on oxygen adsorption capacity and oxidation characteristics of coal samples with different particle sizes

This study is aimed at investigating the effect of particle size on the oxygen adsorption capacity and spontaneous combustion and oxidation of coal, so as to provide guidance for the prevention of spontaneous combustion of residual coal in goafs. First, gas adsorption experiments, low-temperature oxidation (LTO) experiments and electron spin resonance (ESR) experiments were carried out to obtain the oxygen adsorption capacities of coal samples with different particle sizes (less than0.075 mm, 0.075–0.096 mm, 0.096–0.125 mm, 0.125–0.180 mm and 0.180–0.425 mm) and the variations of macroscopic and microscopic characteristic parameters (CO concentration, crossing-point temperature, g-factor, linewidth △H, free radical concentration Ng) during LTO. The results show that the cumulative amount of oxygen adsorption on coal surface presents grows linearly with the rise of adsorption equilibrium pressure. A smaller particle size corresponds to a higher growth rate and larger cumulative amount of oxygen adsorption. At the same temperature, coal samples with smaller particle size generate higher concentrations of CO at higher rates, and the crossing-point temperature decreases with the decrease in particle size. Such a result indicates that coal samples with smaller particle sizes are more capable of oxidizing and self-heating. During LTO, the free radical concentrations of different-sized coal samples increase continuously with the rise of temperature, and the increase differs in different stages. Specifically, after the temperature reaches 150 °C, the rate of coal-oxygen reaction accelerates, and the free radical concentration surges. For the coal sample with the particles size of less than 0.075 mm, the growth of free radical concentration in the temperature range of 150-250 °C accounts for 90.23 % of the total growth. In summary, a smaller particle size and a higher temperature conduce to accelerating the spontaneous combustion and oxidation of coal.

Kinetic study on methylene blue removal from aqueous solution using UV/chlorine process and its combination with other advanced oxidation processes

This study investigated the kinetic degradation of methylene blue (MB) by a UV/chlorine process and its combination with other advanced oxidation processes. The ∙OH and reactive chlorine species (RCS: Cl∙, ClO∙, etc.) were the primary reactive species, which accounted for 56.7% and 37.6% of MB degradation at pH 7, respectively. The second-order rate constant of Cl∙ towards MB was calculated to be 2.8 × 109 M−1 s−1. When the pH increased from 3 to 7, kMB by ∙OH increased from 0.15 to 0.21 min−1 before being reduced to 0.11 min−1 at pH 11. kMB by RCS continuously reduced from 0.16 to 0.13 min−1 when the pH was increased to 11. Humic acid (HA), Br−, and Cl− inhibited the degradation with kMB in the order: kMB (in HA) < kMB (in Br−) < kMB (in Cl−). HCO3− increased kMB from 0.37 to 0.48 min−1. The experimental and modeling methods fit well, indicating the effectiveness of using Kintecus® in predicting concentrations of free radicals in complex water matrices. TOC removal was achieved at 60% after 30 min in a control process and it was strongly inhibited by the presence of HA, with 22% removal achieved at 5 mgc L−1 HA. UV/chlorine/electrochemical oxidation (UV/chlorine/EO) significantly improves kMB from 0.37 to 0.94 min−1 at a high current (240 mA), while UV/chlorine/H2O2 decreased kMB at a low concentration of 0.01 mM H2O2 (kMB decreased by 6.1%). The results indicate that the energy cost for UV irradiation was the main cost in MB treatment in both UV/chlorine and UV/persulfate (UV/PS) processes, accounting for 91% and 84%, respectively.

Heating of consumer cannabis oils can lead to free radical initiated degradation, causing CBD and THC depletion

Commercial cannabis oil products are widely available in Canada even though there is a significant gap in scientific information regarding them. Oils, such as vegetable oils, are known to undergo oxidative changes through free radical mechanisms when they are heated or aged, but the cannabis oils used in this study did not have expiry dates or best-before usage dates. This led to the question of how these products would be affected with time. We hypothesized that cannabis oils would produce increased concentrations of free radicals in aging-simulated conditions, which would be related to a decrease in cannabidiol (CBD) or Δ9-tetrahydrocannabinol (THC) content.Cannabis oils and their respective vehicles (oils) were heated using two protocols: One (moderate aging method) used a 2-day heating protocol at 50 °C, and the other (enhanced aging method) used a 14-day heating protocol at 70 °C. We used electron paramagnetic resonance (EPR) spectroscopy for free radical analysis using the spin trapping technique using 200 mM PBN and 0.02 mM CuCl2 (for peroxide breakdown to free radicals). For active ingredient analysis (CBD, THC), we used LC/MS.Cannabis oils that contained unsaturated oils as their vehicles, such as olive or sunflower oil, all showed varying degrees of free radical formation. In both aged and unaged oils containing CBD or THC, less free radical formation was detected compared to the vehicle controls. Cannabis oils using medium-chain triglycerides (MCT) showed little or no free radical formation. The most significant decrease in CBD or THC was observed in the products using sunflower oil, to a lesser extent in MCT oil, and THC also decreased in olive oil.These findings are important for consumers and policymakers considering using such products in hot beverages or cooking and highlighting the importance of appropriate storage conditions.

Study on the mechanism of free radical scavenger TEMPO blocking in coal oxidation chain reaction

The inhibitory effect of free radical scavenger 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) on the spontaneous combustion process of coal has been experimentally confirmed. However, the mechanism of free radical trapping in coal by TEMPO is not clear. This paper revealed the mechanism of free radical capture in coal by TEMPO from three perspectives by quantum chemistry method, including capture radicals directly, regenerative cycle chain and hydrogen transfer. It was regarded as a beginning that the formation of free radicals (R-CH2∙, CH3∙) by breaking alkane groups in the side chain of the coal molecule. The oxidation process of these free radicals was analyzed and the capturing models of radicals were described. The thermodynamic data for reactions (R2 ∼ R5) are calculated to reveal the initial reaction process of coal. The adsorption energy and thermodynamic data for reactions (Process1 ∼ 4, R6 ∼ R10, R12 ∼ R13) are computed to illustrate spontaneity and difficulty of traps free radicals by TEMPO. The results indicate that the initial reaction (R2, R4) of free radicals with oxygen in coal is exothermic and some other reactions (R3, R5) need to overcome large reaction energy barriers. TEMPO can capture free radicals in coal directly, reducing the concentration of free radicals, and is most effective in capturing ∙OH and alkyl radicals. At the same time, TEMPO can capture peroxide radicals and alkyl radicals in coal through regenerative cycle chains and keep reborn to maintain the efficiency of its capture. For coals under acidic conditions, TEMPO can bind to H+ first, then transfers hydrogen with oxygen-containing radicals in the coal. This process is prone to occur due to the presence of hydrogen bonds. In future applications, the pH value of TEMPO can be appropriately reduced to enhance the effect of capturing free radicals in coal.