Stability Of Free Radicals Research Articles

Effects of gamma and electron-beam irradiations on the stability of free radicals, bioactive compounds and microbial characteristics of turmeric powder

Turmeric is a functional ingredient commonly used in food, pharmaceutical, and cosmetic products due to its health benefits and bioactivity, including anti-inflammatory, antioxidant, and anticancer benefits. Irradiation is a common technique used to decontaminate microorganisms and extend the shelf life of spices. However, there are scientific debates over the use of irradiation in food products. This study aimed to assess the effects of ionizing radiation, including gamma rays and electron beams, on bioactive compounds and microbial characteristics of turmeric powder. Technically, high-performance liquid chromatography with UV–Vis detection was used to assess bioactive compounds. Another aim of the present study was to determine free radicals in irradiated and non-irradiated samples within one month of storage using electron paramagnetic resonance (EPR). Results showed that gamma and electron-beam irradiations could decrease microbial contamination of turmeric by approximately 5 and 6 log cfu/g, respectively. Contents of bioactive compounds increased in irradiated samples and curcumin contents in gamma and electron-beam irradiated samples were 232–248 and 215–266 mg/g dry weight (dw), respectively. Furthermore, the study detected that free radicals increased in all irradiated samples immediately after irradiation but decreased over time. Decrease in EPR signals was faster in gamma-irradiated samples during storage. Numbers of free radicals induced by gamma and electron-beam irradiations were 6.59–4.70, 2.69–1.60, 1.61–1.34, and 0.99–1.05 on days 0, 7, 14, and 21, respectively. After 21 days of storage, the numbers of free radicals in all non-irradiated and irradiated samples were similar. Therefore, free radicals induced by irradiations were degraded during storage and eliminated after 21 days.

Solvated metal complexes for balancing stability and activity of sulfur free radicals

Free radicals can improve the reaction rate, but most of them are unstable due to unpaired electrons. Simultaneously maintaining their stability and activity is challenging. Herein, taking sulfur (S) radicals as an example, we propose a strategy in which solvated metal complexes constructed by Al(acetylacetonate)3 and different solvents can stabilize high concentrations of S radicals with good activity through ion–dipole interactions. Based on this strategy, it is first demonstrated that S4·− is selectively stabilized by controlling the configurations of the solvated complexes. As a result, the reaction rate of S↔Li2S is increased by 8 times, and the energy efficiency and rate capability of the Li–S batteries are significantly improved, especially the 5-fold increase in cell capacities at a low electrolyte/sulfur ratio. This work provides an important strategy in which solvated metal complexes balance the activity and stability of free radicals to accelerate reactions and their application in various fields.

π-conjugated polypyrene network as new electrochemiluminescence emitters: Crosslinked conjugated backbone accelerates charge transport and enhances luminescence

Herein, π-conjugated polypyrene network (CPN) was synthesized by Suzuki-Miyaura polycondensation that exhibited high electrochemiluminescence (ECL) emission. The cross-linked network structure eliminates the aggregation-induced quenching effect of pyrene through steric hindrance. On the one hand, the extended π-conjugated backbone facilitated the acceleration of charge transfer and improved the stability of free radicals in the redox process, and on the other hand, by virtue of the porous structure, the coreactant and electrolyte could diffuse rapidly and fully penetrate into the polymer interior, thus effectively improving the ECL efficiency of the CPN. In view of the excellent ECL performance, an ECL biosensor for the ultrasensitive detection of the lung cancer biomarker microRNA let-7a was constructed by using CPN as a novel ECL probe in combination with a target-triggered rolling circle amplification strategy that exhibited a linear range from 1 aM to 10 pM with a low detection limit of 0.33 aM. In a word, this work provides an effective method to improve the ECL strength of polymers and opens up new prospects for developing new ECL emitters.

Design, Synthesis, and Biological Activity of Coniferyl Aldehyde Derivatives as Potential Anticancer and Antioxidant Agents

Natural products are known to exhibit antimicrobial, anticancer, and antioxidant activities. Among these natural products is cinnamon which contains cinnamaldehyde. Cinnamaldehyde and its derivatives have been reported to have anticancer and antioxidant activities. Coniferyl aldehyde, a non-cytotoxic compound and a cinnamaldehyde derivative, has also been shown to have anticancer activity. In this study, several derivatives of coniferyl aldehyde were synthesized and evaluated for their anticancer and antioxidant activities. Compounds 1, 2, 4, and 8-11 showed cytotoxic activity against H1299 cell line, a non-small cell lung cancer cells, with 4 being the most potent with IC50 value of 6.7 μM. The antioxidant assay experiment showed that compounds 1, 2, and 4 resulted in half the scavenging activity of vitamin C at all tested concentrations. The coniferyl aldehyde itself showed dose-dependent antioxidant activity, with a proposed free radical stabilization mechanism. Thus, our study showed that the synthesized coniferyl aldehyde derivatives exhibit anticancer and antioxidant activities, which might act as potential therapeutic agents.

Mechanism of generation of substituted β-O-4 lignin dimer CH4 based on bimolecular pyrolysis study

Reactants, radicals, intermediates and products during lignin pyrolysis coexisted in a complex pyrolysis system. They interacted with each other and dominate the lignin pyrolysis process. Different from the traditional unimolecular decomposition mechanism, this paper focuses on the bimolecular reaction pyrolysis mechanism. The density functional theory (DFT) GGA/RPBE method was used. A total of 27 β-O-4 type lignin dimer model compounds with different substituents (-OCH3, –OH, –CH2OH) were selected for the study, and 36 reaction pathways were simulated and calculated. The reaction of intermolecular interactions between methyl radicals and lignin was used to explore the effect law of different positions of substituents on intermolecular interactions. The results show that, There were strong interactions between the lignin molecules and methyl radicals, which could promote the pyrolysis of lignin and the stabilization of free radicals. The lignin molecules acted as the hydrogen donor and donated hydrogen to the methyl radical to generate CH4. The hydrogen donation capability of Cα position was better than that of Cβ position, which was more easily influenced by the OCH3 substituent on the A-ring (The benzene ring far from the O atom was the A-ring). Moreover, the OH substituent at the Cα position will facilitate the reaction. Both the A and B rings had an effect on the hydrogen donation capability of Cβ position. Furthermore, the CH2OH substitution at the Cβ position will inhibit the reaction. When the H atoms at the R1 and R2 positions were replaced by OCH3 substituents, the SH-type (S for syringyl unit, H for p-hydroxyphenyl unit) lignin, which has the strongest hydrogen donation capability. SH-type lignin has the strongest interaction with methyl radicals among the types and is the model compound most likely to produce CH4.

Effect of Gamma Irradiation on Fat Content, Fatty Acids, Antioxidants and Oxidative Stability of Almonds, and Electron Paramagnetic Resonance (EPR) Study of Treated Nuts.

Gamma irradiation has been applied as an efficient and inexpensive method for the sterilization of nuts for years. However, along with the benefits of such treatment, negative effects are possible because of the formation of reactive oxygen species with a toxic effect on important biologically active substances. Because of the scarce and contradictory information in the literature about gamma-irradiated almonds, the aim of our work was the examination of the lipid changes, antioxidant activity, and oxidative stability of almonds treated by 10 and 25 kGy gamma rays, as well as changes in intensity of the EPR spectra as an indicator for the stability of radiation-induced free radicals. The results revealed no significant differences in the EPR spectra of almonds treated at 10 and 25 kGy doses, neither in their intensity nor in kinetic behaviour. The EPR signals decayed exponentially over 250 days, with a decreasing of central line by 90%, with satellite lines by about 73%. No significant changes in the fat content, fatty acids composition, and acid value of irradiated almonds were observed. However, the amount of (alpha)tocopherols decreased from 292 to 175 mg/kg, whereas the conjugated dienes and trienes increased, K232 from 1.3 to 3 and K268 from 0.04 to 0.15, respectively, with the increasing of irradiation dose. The same was observed for total polyphenols in defatted almonds (1374 to 1520 mg/100 g), where in vitro antioxidant activity determined by ORAC and HORAC methods increased from 100 to 156 µmol TE/g and from 61 to 86 µmol GAE/g, respectively. The oxidative stability of oil decreased from 6 to 4 h at 120 °C and from 24.6 to 18.6 h at 100 °C (measured by Rancimat equipment). The kinetic parameters characterizing the oxidative stability of oil from 10 kGy irradiated almonds were studied before and after addition of different concentrations of ascorbyl palmitate as a synergist of tocopherols. Its effectiveness was concentration-dependent, and 0.75 mM ensured the same induction period as that of non-irradiated nut oil. Further enrichment with alpha-tocopherol in equimolar ratio with palmitate did not improve the oil stability. In conclusion, gamma irradiation is an appropriate method for the treatment of almonds without significant changes in fat content and fatty acids composition. The decreasing of oxidative stability after higher irradiation could be prevented by the addition of ascorbyl palmitate.

The impact of free-radical stabilization techniques on in vivo subsurface mechanical properties in highly cross-linked polyethylene acetabular liners.

Highly cross-linked polyethylene (HXLPE) for total hip arthroplasty was developed to improve wear resistance in vivo and associated complications in comparison to ultrahigh molecular weight polyethylene. This material typically goes through various free-radical stabilization techniques by remelting, single-annealing, or sequentially annealing the polyethylene to improve in vivo oxidation and wear properties. The purpose of this study is to determine if there is evidence of subsurface microhardness changes in retrieved HXLPE liner at the rim and articular subsurface after extended in vivo time that could be associated with oxidation and its effects on mechanical properties and implant integrity. Retrieved HXLPE liners were chosen based on peak subsurface Fourier transform infrared spectroscopy oxidation values. Each was mechanically tested for subsurface microhardness at both the rim and articular surface using a validated microindentation technique. Rim testing demonstrated a decrease in mechanical integrity that corresponded to higher subsurface oxidation values regardless of the free-radical stabilization technique. At the articular surface, a decrease in mechanical integrity was observed near the surface corresponding to peak oxidation and Vicker's hardness, which decreased with increasing depths. This was found in all groups, with the exception of the single-annealed liners, which demonstrated decreased mechanical integrity trends at greater depths between 1.0 and 2.0 mm. Our results suggest that subsurface mechanical properties do change in vivo for certain implants. Though it is likely that the mechanical failures are multifactorial, we have shown that mechanical property degradation of HXLPE liners does occur with long-term in vivo exposure and should be considered a possible risk factor.

Carotenoids production and genome analysis of a novel carotenoid producing Rhodococcus aetherivorans N1

Carotenoids are a series of natural pigments with unique structure and physiological functions. In this study, a novel Rhodococcus aetherivorans strain N1 was discovered, which can produce 6.4 mg/g carotenoids including β-carotene, zeaxanthin and isorenieratene from glucose. Moreover, strain N1 can directly produce 3.0 mg/g carotenoids from the undetoxified straw hydrolysate, representing the highest carotenoids production from the undetoxified lignocellulosic hydrolysate. The crude carotenoid extracts of strain N1 showed efficient free radical scavenging activity and stability. Strain N1 has complete methylerythritol 4-phosphate (MEP) pathway and related genes for carotenoid synthesis, especially the rare aromatic carotenoid of isorenieratene. Genomic comparison between strain N1 and other carotenoid producing Rhodococcus sp. strains showed the conservatism and universality of carotenoids synthesis gene. These results proved that R. aetherivorans strain N1 can serve as a promising producer for the industrialization of carotenoid production.

Synthesis of platinum decorated copper oxide doped layer graphite carbon nitrite: An efficient photocatalyst for disintegration of bacteria and decomposition of dye

Platinum decorated copper oxide doped layer graphite carbon nitrite (Pt/CuO@g-C 3 N 4 ) was synthesized by green hydrothermal method. Amylopectin was employed as a source of reduction and stabilization. Aforementioned nanomaterial is made up of a layer graphite carbon nitrite nanosheet with CuO nanofibers and Pt embedded in a cluster of nanofibers. Methylene blue (MB) degradation, free radical stabilization, and photo inactivation of bacteria were all targets for the synthesized photocatalyst. For instance, the developed composites exhibited the remarkable photocatalytic activity to degrade 90% MB in about 20 minutes, under visible light irradiation. Moreover, the synthesized nanomaterials were also tested against bacteria Staphylococcus aureus and Escherichia coli (S. aureus & E. coli ) both in the presence and absence of visible light irradiation. The light-treated platinum adorned copper oxide doped layer graphite carbon nitrite has inhibitory diameter 13 and 18 mm for E. coli and S. aureus respectively though in dark was 7 and 10 mm respectively. The effects of various factors on the photoinhibition potency of the said nanomaterial were also investigated. Furthermore, the nanomaterial exhibits a high resistance to 2,2-diphenyl-1-picrylhydrazyl (DPPH) stabilization. • Preparation of Platinum decorated Copper Oxide doped Layer Graphite Carbon Nitrite by simple, non-toxic way • Antibacterial activity examination • Examination of MB degradation • DPPH scavenging activity examination

Novel insights into the catalytic effect of hydrogen bonds on aldehyde groups generation during direct coal liquefaction

Direct coal liquefaction (DCL) is considered to be the effective method for production of aviation fuel and valuable chemicals, while low rank coal is appropriate feedstock because of high thermal reactivity. Original hydrogen bonds could promote low-temperature crosslinking reactions. liquefaction solvents could partially break original hydrogen bonds by forming new species. Impacts of hydrogen bonds formed by solvents on DCL reactions have rarely been studied. In order to figure out role of hydrogen bonds in DCL, a conjoint study of DCL experiments and density functional theory (DFT) calculations was carried out. More carboxyl groups were promoted to decompose. Meanwhile more aldehyde groups were found in solid products with increase of liquefaction temperature. As aldehyde groups are generated, hydrogen consumption increases. In terms of mechanism, effect of stronger hydrogen bonds on cleavage of covalent bonds were investigated by DFT-based potential energy surface scan. It turns out that cleavage of CO bonds in carboxyl groups could be enhanced, so that stabilization of free radicals results in consumption of extra hydrogen, which is provided by tetralin. Results of experimental methods are consistent with DFT calculations. The catalytic mechanism of hydrogen bonds upon conversion of carboxyl groups during DCL is proposed. Hydrogen bonds between coal and liquefaction solvents promote decomposition of carboxyl groups and consequently improve hydrogen transfer and thermal reactivity of solid products. Consequently, hydrogen bonds modulation should be taken into account during preparation of DCL solvents, for suppression of crosslinking reactions.

Study on the species and stability of free radicals in bisphenol-A based epoxy resin induced by γ irradiation up to 1000 kGy

Epoxy resins are radiation-resistant polymers that are widely employed in aerospace and nuclear facilities; however, free radicals formed by ionizing radiation may lead to changes in their physicochemical properties. In this study, bisphenol-A based epoxy resin samples in both air and vacuum environments were subjected to gamma irradiation with doses up to 1000 kGy and the generated free radicals were investigated by electron spin resonance (ESR). Four radicals, namely cyclohexadienyl-type radicals, phenoxy radicals, peroxy radicals, and alkyl radicals, were formed in epoxy resin in both environments after gamma irradiation. The ESR spectra showed that the free radicals yield produced in the air was significantly larger than that produced in a vacuum. The radical concentration of the EP increased until a dose of 500 kGy and approached saturation upon increasing the dose to 1000 kGy. The ESR spectra of the EP annealed between 50 and 160 °C indicated that the radical concentration decreased with increasing temperature. The radicals in the EP samples irradiated in air disappeared at an annealing temperature of 130 °C, close to the glass transition temperature of the EP. The radicals in the EP irradiated in vacuum still remained even at 160 °C, which can be attributed to the stable phenoxy radicals. The free radical reaction mechanism was also developed for the bisphenol-A based EP irradiated by gamma-ray in different atmospheres.

Antioxidant and Antitumoral Potential of Terpenes and Phenylpropanoids against MCF7, A549 and HT144 cancer cell lines

Essential oils are a complex mixture of terpenes and phenylpropanoids that have several biological activities, including antioxidant and antitumoral activities. The present study sought to evaluate the antioxidant potential of monoterpenes and phenylpropanoids by different methods (stabilization of free radicals, inhibition of lipid peroxidation, and complexation of metals). In addition, the antitumor potentials of these compounds were evaluated on human estrogen-positive breast cancer (MCF-7), non-small cell lung cancer (A-549), and melanoma cancer (HT-144) cell lines. Cisplatin (6 µg mL-1) was used as a positive control. The cell viability was studied and the quantification of DNA was performed. The antioxidant activity results were analyzed by linear regression and antitumor activity were analyzed via analysis of variance and the Dunnett test. A greater antioxidant activity was observed for the phenolic compounds carvacrol, thymol and eugenol than for the standards (BHT, mannitol and ascorbic acid) by the methods tested. A dose-response effect was observed for the less active compounds, revealing the influence of the concentration of the constituents. Carvacrol displayed an important cytotoxic activity against the estrogen-positive MCF-7 cell line, and citral was more active against A549 cells and HT144 melanoma cells. The positive control Cisplatin showed low cell viability over the A549 and HT44 cells, and showed high cell viability over the MCF-7 cell. The antitumor activity of citral observed against HT144 cells is associated with its ability to promote the cell cycle at the G1/S transition, at least in part.

Characterization of glucose-crosslinked gelatin films reinforced with chitin nanowhiskers for active packaging development

To find renewable and sustainable alternatives to reduce the severe environmental impact of single-use synthetic plastic packaging, glucose-crosslinked gelatin films containing different amounts of chitin nanowhiskers (CNWs) were prepared. CNWs were first prepared by acid hydrolysis of chitin from shrimps, and characterized (morphological and thermal properties), before their addition into film-forming formulations. The films were heat-treated to promote the chemical crosslinking Maillard reaction (MR), between glucose and gelatin. The films then became less soluble (from 100% to ∼10%), thermally more stable, had a notably improved UV–vis light absorption capacity, and presented significantly enhanced tensile strength (from 42 to 77 MPa) and Young's modulus (from 1476 to 2921 MPa), however, they also became less flexible (from 17% to 7%) and transparent. These property alterations were mainly related to changes in crystallinity, the MR and to a lesser extent, to the formation of noncovalent (electrostatic and hydrogen bonding) interactions between CNWs and gelatin. Furthermore, due to the formation of MR products, the films turned yellow/dark brown and released antioxidant compounds (inhibition ∼33%) while immersed in water, which gave the films their active properties (stabilization of free radicals). These films have considerable potential as reinforced active packaging films for renewable food packaging applications.

Stabilization of free radicals in layer-by-layer nanoarchitectures containing multiple arylenediimides

Layer-by-layer thin films of arylenediimides were grown on phosphonate-primed silicon and quartz substrates by the zirconium phosphonate method. The method consists in depositing alternated organic/inorganic layers, where the organic layer was a phosphonate-substituted arylenediimide and the inorganic layer was Zr4+. Heterogeneous films with up to 50 layers, containing different imides, were produced. The building blocks were N,N′-bis(2-phosphonoethyl)pyromellitimide (PPMI), N,N′-bis(2-phosphonoethyl)-1,4,5,8-naphthalenediimide (PNDI) and N,N′-bis(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI). Thin films with the sequence PPDI/PNDI, PPDI/PPMI, PNDI/PPMI and PPDI/PNDI/PPMI were produced. Organized film growth was observed by UV–visible–NIR spectroscopy (quartz substrates) and ellipsometry (silicon substrates). AFM images showed that the surface of the films was smooth and uniform. The imides in the films were reduced using sodium dithionite as a reducing agent, generating stable radical anions and dianions of the imides. The following species were detected in the absorption spectra of the reduced films: PPDI−∙, PPDI2−, PNDI−∙, and PNDI2−. Reduction of the imides in the films was rather slow, as compared to homogeneous solutions. When the reduced films were exposed to atmospheric oxygen, reoxidation took place, which was also much slower than in homogeneous solutions. In conclusion, a mix of aromatic imide reduced species, absorbing through the whole visible range, was produced and stabilized in thin films.

The Impact of Free Radical Stabilization Techniques on in vivo Mechanical Changes in Highly Cross-Linked Polyethylene Acetabular Liners

IntroductionNumerous thermal free radical stabilization techniques are used in the production of highly cross-linked polyethylene (HXLPE) to improve oxidative stability. Little knowledge exists on the effects of in vivo time on the mechanical properties of HXLPE. The purpose of this study was to determine if free radical stabilization of HXLPE impacts mechanical properties as well as oxidative stability of acetabular liner rims after extended in vivo time.MethodsRetrieved and control remelted, single annealed and sequentially annealed HXLPE liner rims were tested for mechanical properties. Oxidation was measured with FTIR spectroscopy and crystalline phase composition measured with Raman spectroscopy.ResultsNo correlation was found between in vivo, ex vivo time and hardness for annealed groups. A statistically significant difference in hardness was identified between free radical stabilization groups. No correlation between maximum rim oxidation and in vivo time was found. Detectable levels of rim oxidation were present in 100% of single annealed, 75% of sequentially annealed, and 25% of remelted retrieved liners. Single and sequentially annealed liners demonstrated oxidation and increased crystallinity. Rim mechanical properties change in vivo for implant types. With in vivo time, retrieved remelted HXLPE demonstrated decreased mechanical properties, whereas retrieved single and sequentially annealed HXLPE properties remained stable. All liner cohorts demonstrated evidence of rim oxidation. Subsequent changes in crystallinity were only observed in oxidized annealed liners.ConclusionHXLPE acetabular liner rims show evidence of in vivo mechanical property degradation, notably in remelted HXLPE, which may be a risk factor in rim fracture and catastrophic implant failure.

Effects of γ-radiation on structure and properties of poly(lactic acid) filaments

Poly(lactic acid) (PLA), compared to other biodegradable polymers, has one of the highest consumption volumes in the world. Due to its specific properties, especially those that make it ecologically acceptable, it has a wide application from food packaging to medical implants. In this work, commercially available 3D printing filament of PLA was used. The objective was to investigate the effects of γ-radiation on structural changes, mechanical and thermal behaviour of the material. The samples were irradiated with total doses of 25 kGy, 50 kGy, 100 kGy and 200 kGy. The experimental techniques used to investigate the structural changes in PLA filaments were electron spin resonance (ESR) and gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) and universal testing machine were applied in monitoring changes in thermal and mechanical behaviour, respectively. The formation and stability of free radicals were studied by ESR, which confirmed that the radical concentration depends on the applied absorbed dose, while the spectral lineshape appears to be dose independent. The loss of the ESR signal, directly related to the decrease of radical concentration, was monitored as a function of time for all applied absorbed doses. The breaking force and the Young's modulus were determined and compared. Results have shown that both the concentration and decay rate constant of radicals depend on the absorbed dose. Compressive strength test, a new approach in considering the mechanical changes in irradiated PLA indicated a loss of material elasticity and an increase of brittleness by increasing absorbed dose.

Oxidation Characteristics of Functional Groups in Relation to Coal Spontaneous Combustion.

To investigate and better understand the mechanism of coal spontaneous combustion, the distributions, evolution, and oxidation characteristics of functional groups in different coal samples were characterized using in situ Fourier transform infrared (FTIR) and electron paramagnetic resonance (EPR) experiments. The macroscopic characteristics of coal spontaneous combustion in relation to functional groups were also analyzed using the thermogravimetric/differential scanning calorimetry–FTIR coupling technique. The experimental results indicated that −OH was the most active groups of coal spontaneous combustion. It not only could react with the absorbed oxygen spontaneously but also found to be the main product of the chemisorption. Consequently, −OH was believed to contribute most both for the loss and increase of coal mass during the process of spontaneous combustion. Aliphatic hydrocarbons were the main components to form −C–O–O• and could be further oxidized into C=O. However, reactions between aliphatic hydrocarbons and oxygen were nonspontaneous. EPR experiments suggested that the tendency of coal spontaneous combustion acutely depended on the stability and survival time of free radicals. The more the stable and longer survival time of free radicals are, the lower the tendency of coal spontaneous combustion is.

Synthesizing Hindered Structure Poly (p‐Phenylenediamine) by Enzymatic Catalysis and Evaluating Its Antioxidation Mechanism in Biodegradable Castor Oils

AbstractIn this study, poly(p‐phenylenediamine) (PPDA) was synthesized by an enzymatic polymerization method using p‐phenylenediamine as the monomer in the water phase. The PPDA structure was characterized by infrared (IR), gel permeation chromatography, and elemental analysis. The antioxidation behavior of the as‐synthesized PPDA in biodegradable castor oil was investigated using a rotary oxygen bomb test and pressurized differential scanning calorimetry. A theoretical calculation was conducted to investigate its antioxidation mechanism. PPDA was found to exhibit excellent oxidation resistance in castor oil at 150 °C, which effectively prolonged the oxidation induction time of the oil. The results obtained herein suggest that as with phenolic antioxidants, PPDA with a hindered structure effectively improves the antioxidation performance of the oil by enhancing the stability of nitrogen free radicals.

Bromobenzal thiosemicarbazones of ruthenium(II) complexes: Synthesis and bio applications

ABSTRACT Ru(II)BT have been synthesized by the reaction between substituted bromobenzal thiosemicarbazones and precursors of ruthenium metal complexes, [RuHCl(CO)(EPh3)3] (where E = P/As). The bromobenzal thiosemicarbazones and Ru(II)BT was characterized by analytical and spectroscopic techniques. It confirms the coordination of the thiosemicarbazone ligands and suggest the octahedral geometry of the complexes. The Ru(II)BT is comprised of a metal centre with bidentate ligands. The stabilization of free radicals with Ru(II)BT was studied. The ligand and Ru(II)BT have significant anticancer activity on MCF-7 cancer cells.

Hydrocracking of C5-Deasphalted Oil:\t\t\tEffects of H2 and Dispersed Catalysts

Thermal cracking of C5-deasphalted oil\t\t\t\t\t\t(C5-DAO) was performed in a batch reactor at 410°C in\t\t\t\t\tthe absence and presence of H2 gas and catalysts. Coke\t\t\t\t\twas formed during the thermal cracking of C5-DAO even\t\t\t\t\tthough the feed contained no asphaltenes. Although H2\t\t\t\t\tsuppressed asphaltene formation and decreased the coke yield, coke was still\t\t\t\t\tformed in the absence of a catalyst. A slurry-phase dispersed catalyst inhibited\t\t\t\t\tthe transformation of resins into heavier fractions and facilitated <1 wt %\t\t\t\t\tasphaltene yield with no coke formation even under high conversion conditions.\t\t\t\t\tThe main function of the catalyst was the facilitation of hydrogenation\t\t\t\t\treactions and the stabilization of free radicals, leading to liquid production\t\t\t\t\tby inhibiting coke formation. Consequently, the product quality, in terms of\t\t\t\t\thydrogen to carbon ratio and microcarbon residue and S contents, was enhanced by\t\t\t\t\tcatalytic hydrocracking.