Small Hydrocarbons Research Articles

Ruthenium-Substituted Polyoxoanion Serves as Redox Shuttle and Intermediate Stabilizer in Selective Electrooxidation of Ethylene to Ethylene Glycol.

The high carbon intensity of present-day ethylene glycol (EG) production motivates interest in electrifying ethylene oxidation. Noting poor kinetics in prior reports of the organic electrooxidation of small hydrocarbons, we explored the design of mediators that activate and simultaneously stabilize light alkenes. A ruthenium-substituted polyoxometalate (Ru-POM, {Si[Ru(H2O)W11O39]}5-) achieves 82% faradaic efficiency in EG production at 100 mA/cm2 under ambient conditions. Via the union of in situ spectroscopic techniques, electrochemical studies, and density functional theory calculations, we find evidence of a two-step oxidation mechanism: Ru-POM first undergoes electrochemical oxidation to the high valent state, activating ethylene via partial oxidation and forming an intermediate complex; this intermediate complex then migrates to the anode where it undergoes further oxidation to produce EG. The Ru-POM-mediated electrocatalytic system reduces the projected energy consumption required in EG production, requiring 9 GJ per ton of EG (and accompanied by 0.04 ton H2 coproduction), compared to 20-30 GJ/ton in typical prior processes.

Study on high-temperature emission behaviors of crumb rubber modified asphalt: Experimental analysis and molecular simulation approach

The harmful emissions produced during the manufacturing and construction processes of crumb rubber modified asphalt (CRMA) significantly hinder its widespread application. Addressing this issue hinges on a thorough investigation into the mechanism governing its high-temperature emissions. This study employed microscale testing methods to analyze the microstructure and chemical property disparities between CRMA and base asphalt (BA). Subsequently, the impacts of varying crumb rubber (CR) content, experimental temperature, and sulfur stabilizer dosage on the high-temperature emissions of CRMA were investigated. Furthermore, comparative analyses of the molecular weight distribution, emission species, and CR crosslink density in asphalt after the fume experiment were conducted to further elucidate the high-temperature emission mechanisms. Finally, molecular simulation techniques were employed to analyze the interactions between CR and the four fraction molecules of asphalt at the microscale. The results indicated that the fume release volume of CRMA initially decreased and then increased with the addition of CR, while both the experimental temperature and sulfur stabilizer content exhibited a positive correlation with emission volume. CR reduced the volatilization of some small molecular hydrocarbons in the BA by absorbing light fractions. Meanwhile, excessive swelling caused the crosslinking density of CR to decrease by 77 %, which led to the release of toxic substances. At 20% CR content, the overall emissions of CRMA achieve their lowest level; however, the emission of toxic gases does not diminish. Molecular simulations have also confirmed the above results, showing that there is a strong interaction between CR and the light fractions. Compared with asphaltene molecules, rubber molecules had higher molecular polarity and stronger adsorption behavior for light fraction molecules.

Catalytic asymmetric fragmentation of cyclopropanes.

The stereoselective activation of alkanes constitutes a long-standing and grand challenge for chemistry. Although metal-containing enzymes oxidize alkanes with remarkable ease and selectivity, chemical approaches have largely been limited to transition metal-based catalytic carbon-hydrogen functionalizations. Alkanes can be protonated to form pentacoordinated carbonium ions and fragmented into smaller hydrocarbons in the presence of strong Brønsted acids. However, catalytic stereocontrol over such reactions has not previously been accomplished. We show here that strong and confined acids catalyze highly enantioselective fragmentations of a variety of cyclopropanes into the corresponding alkenes, expanding the boundaries of catalytic selective alkane activation. Computational studies suggest the involvement of the long-debated cycloproponium ions.

Investigating the oxidation characteristic of a hydro-processed bio-jet fuel: Experimental and modeling study

A rapid transition from conventional jet fuels to sustainable aviation fuels (SAFs) is imperative in order to reduce carbon emissions. Hydro-processed esters and fatty acids synthetic paraffinic kerosene (HEFA-SPK), as a type of SAF, exhibits broad applications. In this study, a new HEFA-SPK named ZH-HEFA was investigated. The fuel comprises 14% n-alkanes, 85% iso-alkanes and only 1% cycloalkanes by weight, with the majority of alkanes ranging from C9 to C17. Oxidation experiments of the fuel were conducted using an atmospheric pressure flow reactor at temperatures ranging from 550 K to 1075 K under three equivalence ratios (0.5, 1.0 and 1.5). Species mole fraction profiles were measured by an on-line gas chromatographic (GC). For comparison purposes, an experiment was also performed on RP-3, a conventional jet fuel commonly used in China, under the equivalence of 0.5. Compared to RP-3, ZH-HEFA exhibited significantly stronger low temperature reactivity and higher combustion conversion rates while demonstrating considerably lower yields of aromatics at high temperatures. The kinetic simulation of ZH-HEFA was achieved by proposing two surrogates and their corresponding kinetic models. Surrogate S-1 consisted solely of n-dodecane, while S-2 comprised 35% n-dodecane and 65% 2,6,10-trimethyl dodecane by weight. Both surrogate models were validated by the experimental data. S-1 exhibited a closer resemblance to the global oxidation characteristics of ZH-HEFA, whereas S-2 demonstrated improved accuracy in predicting the formation of small hydrocarbon intermediates during the fuel oxidation. Rate of production analysis revealed that the branched alkane component in S-2 possessed more pathways and greater capability than S-1 in generating C3 intermediates, which are important for the generation of aromatics. Furthermore, both models displayed good predictive performance for the auto-ignition properties of HEFA-SPK fuels.-

Surface-Activated Mechano-Catalysis for Ambient Conversion of Plastic Waste.

Improved recycling technologies can offer sustainable end-of-life options for plastic waste. While polyolefins can be converted into small hydrocarbons over acid catalysts at high temperatures, we demonstrate an alternative mechano-catalytic strategy at ambient conditions. The mechanism is fundamentally different from classical acidity-driven high-temperature approaches, exploiting mechanochemically generated radical intermediates. Surface activation of zirconia grinding spheres creates redox active surface sites directly at the point of mechanical energy input. This allows control over mechano-radical reactivity, while powder catalysts are not active. Optimized milling parameters enable the formation of 45% C1-10 hydrocarbons from polypropylene within 1 h at ambient temperature. While mechanochemical bond scission is undesired in plastic production, we show that it can also be exploited for chemical recycling.

Smoke Points: A Crucial Factor in Cooking Oil Selection for Public Health

: Cooking oils and fats play a significant role in our daily diet and culinary practices by enhancing flavours, textures, and nutritional value. However, overheating these fats can compromise the quality and safety of cooked foods. When oils and fats exceed their smoke points, they undergo chemical breakdown, producing volatile compounds, off-flavours, and undesirable odors, including harmful substances like small chain fatty acids, trans fats, acrylamides, and polycyclic aromatic hydrocarbons. It is crucial to avoid overheating oils to mitigate the formation of these toxic substances and instead opt for those with higher smoke points for high-temperature cooking methods. The smoke point, indicating the temperature at which visible smoke is emitted, serves as a critical indicator of thermal stability and suitability for various cooking oils and fats. Therefore, understanding and considering the smoke points of different oils and fats are essential for maintaining food quality and safety in culinary practices. This review consolidates existing knowledge on the smoke points of various oils and fats and methods for determining smoke points, providing a list of fifty-one oils and fats with their respective smoke points and highlighting their applications in cooking. By considering the smoke point, chefs, cooks, and food manufacturers can select oils that optimize cooking, frying, taste, texture, flavour enhancement, salad dressings, marinades, baking, and overall safety in their culinary practices. Mindfulness of the smoke point helps prevent the degradation of nutritional value and the generation of harmful compounds during the cooking process.

Evolution of PTCDA-derived seeds prior to graphene nanoribbon growth on Ge(001)

The synthesis of graphene nanoribbons (GNRs) can be realized via CH4 chemical vapor deposition (CVD) on substrates such as Ge(001) that promote highly anisotropic growth. Small polycyclic aromatic hydrocarbons (PAHs) are first sublimed onto Ge at relatively low temperature to form graphene-like seeds that subsequently initiate GNR growth with CH4 exposure at 1173 K. The behaviors of PAHs between their sublimation onto Ge and GNR growth are unclear. Here, we study an archetypical PAH – perylene-3,4,9,10-tetracarboxyl acid dianhydride (PTCDA) – on Ge(001) using both scanning tunneling microscopy (STM) and density functional theory (DFT) to characterize PAH configuration, surface diffusivity, and clustering. PTCDA becomes mobile above 673 K, consistent with a DFT diffusion barrier of 1.74 eV. The mobile PTCDA molecules meet, cluster, and fuse at Ge step edges, dehydrogenating at higher temperatures. These clusters have a height of 0.4 nm, similar to small graphene islands, and grow laterally with increasing temperature – reaching 1.2–2.1 nm in width at 1173 K, consistent with extrapolated CVD experiments. These results provide a plausible picture for how PTCDA forms seeds for anisotropic GNR CVD and show that PAHs with reduced surface diffusivity and inter-molecular reactivity are needed to enable more monodisperse PAH-seeded GNR synthesis.

Efficient Reaction‐Based Approaches for Gas‐Phase Enthalpy of Formation Prediction and their Application to Large (C32) Polycyclic Aromatic Hydrocarbons

AbstractIn this work, an efficient and generally applicable scheme for the automatic generation of the minimal set of independent model reactions to be used for the calculation of enthalpies of formation is presented. A post‐processing procedure targeting the selection of the most suitable model reactions by assigning them larger weights is suggested. The developed computational protocol exploiting high‐level ab initio calculations and accurate reference enthalpies of formation retrieved from the Active Thermochemical Tables reproduces with chemical accuracy well‐established enthalpies of formation of 15 relatively small (C10–C24) polycyclic aromatic hydrocarbons (PAHs). A promising alternative single‐reaction strategy encompassing all reference species is outlined. Both methods are then applied to predict for the set of 43 larger (C32) PAHs, and revealed significant deviation (Mean Unsigned Error, MUE = 23.2 kJ mol−1) compared to the earlier theoretical results obtained from B3LYP calculations with subsequent group‐based empirical corrections. In the absence of the experimental data, these evaluations of are expected to be more realistic as the approach employed in this work demonstrated better performance on the benchmarking set of 15 smaller PAHs with the MUE of 1.3–1.5 versus 6.2 kJ mol−1.

Upcycling of waste disposable medical masks to high value-added gasoline fuel and surfactants products by sub/supercritical water degradation and partial oxidation

The amount of waste disposable medical masks (DMMs) and the potential environmental risk increased significantly due to the huge demand of disposable medical surgical masks. In this study, two effective and environmentally friendly processes, supercritical water degradation (SCWD) and subcritical water partial oxidation (SubCWPO), were proposed for the upcycling of DMMs. The optimal conditions for the SCWD process (conversion ratio>98 %) were 410 ℃, 15 min, and 1:5 g/mL. The oil products obtained from the SCWD process were mainly small molecule hydrocarbons (C7-C12) with a content of 86 % and could be recycled as fuel feedstock for gasoline. Alkyl radicals in the SCWD reaction formed double bonds and ring structures through hydrogen capture reactions, β-scission, and dehydrogenation reactions, and aromatic hydrocarbons were formed by olefin cyclization and cycloalkane dehydrogenation. The introduction of an oxidant (H2O2) to the reaction system could significantly reduce the reaction temperature and shorten the reaction time. At 350 ℃, 15 min, 1:20 g/mL, V(H2O2): V (H2O) of 1:1, the conversion ratio of the SubCWPO process was 88 %, which was higher than that of the SCWD process at 400 ℃ (71.49 %). Oil products produced from the SubCWPO process were rich in alcohols and esters, which could be used as raw materials for nonionic surfactant of polyol and fatty acid ester. The abundant hydroxyl radical in the SubCWPO system trapped hydrogen atoms on PP and reacted with the resulting alkyl radical to form alkanols, which was oxidized to form acids. The esterification of acids and alkanols formed high level of esters. The SCWD and SubCWPO processes proposed in this study are believed to be promising strategies for DMMs degradation and the recovery of high value-added hydrocarbons.

Advancing Pore‐Space‐Partitioned Metal–Organic Frameworks with Isoreticular Cluster Concept

AbstractTrigonal planar M3(O/OH) trimers are among the most important clusters in inorganic chemistry and are the foundational features of multiple high‐impact MOF platforms. Here we introduce a concept called isoreticular cluster series and demonstrate that M3(O/OH), as the first member of a supertrimer series, can be combined with a higher hierarchical member (double‐deck trimer here) to advance isoreticular chemistry. We report here an isoreticular series of pore‐space‐partitioned MOFs called M3M6 pacs made from co‐assembly between M3 single‐deck trimer and M3x2 double‐deck trimer. Important factors were identified on this multi‐modular MOF platform to guide optimization of each module, which enables the phase selection of M3M6 pacs by overcoming the formation of previously‐always‐observed same‐cluster phases. The new pacs materials exhibit high surface area and high uptake capacity for CO2 and small hydrocarbons, as well as selective adsorption properties relevant to separation of industrially important mixtures such as C2H2/CO2 and C2H2/C2H4. Furthermore, new M3M6 pacs materials show electrocatalytic properties with high activity.

Advancing Pore-Space-Partitioned Metal-Organic Frameworks with Isoreticular Cluster Concept.

Trigonal planar M3(O/OH) trimers are among the most important clusters in inorganic chemistry and are the foundational features of multiple high-impact MOF platforms. Here we introduce a concept called isoreticular cluster series and demonstrate that M3(O/OH), as the first member of a supertrimer series, can be combined with a higher hierarchical member (double-deck trimer here) to advance isoreticular chemistry. We report here an isoreticular series of pore-space-partitioned MOFs called M3M6 pacs made from co-assembly between M3 single-deck trimer and M3x2 double-deck trimer. Important factors were identified on this multi-modular MOF platform to guide optimization of each module, which enables the phase selection of M3M6 pacs by overcoming the formation of previously-always-observed same-cluster phases. The new pacs materials exhibit high surface area and high uptake capacity for CO2 and small hydrocarbons, as well as selective adsorption properties relevant to separation of industrially important mixtures such as C2H2/CO2 and C2H2/C2H4. Furthermore, new M3M6 pacs materials show electrocatalytic properties with high activity.

Dynamics of the Decomposition of Gas Molecules Containing Sulfur and Nitrogen from Char-S and Char-N Structures in Combustion and Pyrolysis Reactions

ABSTRACT Combustion states of char-S (C14H16O4S) and char-N (C18H19NO3) sub function molecules in a limited number of oxygen environments and pyrolysis states at high temperatures were examined quantum mechanically. In the study, the formation of all gases, with or without carbon, were determined. All the dynamics in which the O2 molecule could be effective in the combustion mechanism and all the elements that could affect the decomposition in the pyrolysis event were determined. The dynamics of the formation and disappearance of the highly stable CO molecule and CH2O (formaldehyde) molecules were shown in detail. It has been shown that the CO molecule is a catalysis that can bond with hydrocarbon groups and decompose them into small hydrocarbon groups at high temperature. In this study, it was shown that high temperature-dependent vibration and rotational energies, CO molecule and H-atom transfers play a role in the decomposition in the pyrolysis system, and the aromatic carbon ring group is the last particle group to decompose. In addition, the formation and dissociation dynamics of sulfoxylic acid, thioformic acid, hydrogen sulfide molecules originating from the Char-S system, as well as the formation conditions of hydrogen cyanide and pyridinyl molecules originating from the Char-N system, were determined. The study also showed that since the N-atom is located in the aromatic carbon ring, it makes the emergence of the nitrous oxide molecule difficult in pyrolysis systems.

Numerical study on soot formation in ammonia/ethylene laminar counterflow diffusion flame

The ammonia addition can significantly inhibit soot formation in hydrocarbon fuel flames. However, due to the complexity of the interaction between nitrogen and hydrocarbon, the inhibiting effect of NH3 addition on soot formation has not been fully understood yet. In this study, a mechanism is constructed through mechanism comparison, reduction, and merging. The constructed mechanism includes ammonia, polycyclic aromatic hydrocarbons (PAHs), and nitrogen-containing aromatic compounds (NACs) sub-chemistry. Then the constructed mechanism is coupled with a soot model to conduct a series of simulations of ammonia/ethylene laminar counterflow flames with various ammonia doping ratios. The results show that the constructed model can reproduce the suppression effect of ammonia addition on soot formation well. To explain the chemical inhibiting effect, the rate of production (ROP) and reaction pathway are analyzed. It can be concluded that the main formation pathway of benzene is C2H4 → C2H3 → C2H2 → C3H3 → A1. The decomposition of ammonia consumes H radical which is necessary for the conversion of C2H4 to C2H3, leading to a decrease in the reaction rates along the benzene formation pathway. Moreover, the N-containing species react with the small hydrocarbon molecules/radicals to form hydrogen cyanide (HCN), in which the reaction between C2H2 and N radical is the largest contributor. Compared to the reactions between C1-C2 species and nitrogen-containing species, the reactions between C3 species and nitrogen-containing species contribute less to the chemical effect of NH3 addition. All these reactions reduce the carbon flux of the benzene formation path. In addition, the impact of reactions between HCN and aromatic hydrocarbons which produce NACs is also investigated. The reactions of HCN addition to benzene and naphthalene compete with the C2H2 addition reactions, resulting in a slightly enhanced inhibiting effect of ammonia addition on soot formation.

Utilizing metabolomics and network analysis to explore the effects of artificial production methods on the chemical composition and activity of agarwood.

Introduction: Agarwood is a traditional aromatic southern medicine. It has a long history of being used in traditional Chinese aromatherapy to treat insomnia, anxiety and depression. Due to the scarcity of wild resources, people have planted trees successfully and begun to explore various agarwood-inducing techniques. This study comparative analysis of volatile metabolites in agarwood produced by various inducing techniques and its potential sleep-promoting, anti-anxiety and anti-depressant network pharmacological activities. Methods: A total of 23 batches of two types of agarwood were collected, one of which was produced by artificial techniques, including 6 batches of TongTi (TT) agarwood produced by "Agar-Wit" and 6 batches of HuoLao (HL) agarwood produced by "burning, chisel and drilling", while the other was collected from the wild, including 6 batches of BanTou (BT) agarwood with trunks broken due to natural or man-made factors and 5 batches of ChongLou (CL) agarwood with trunks damaged by moth worms. The study employed metabolomics combined with network analysis to compare the differences in volatile metabolites of agarwood produced by four commonly used inducing techniques, and explored their potential roles and possible action targets in promoting sleep, reducing anxiety, and alleviating depression. Results: A total of 147 volatile metabolites were detected in agarwood samples, mainly including small aromatic hydrocarbons, sesquiterpenes and 2-(2-phenylethyl) chromone and their pyrolysis products. The results showed composition of metabolites was minimally influenced by the agarwood induction method. However, their concentrations exhibited significant variations, with 17 metabolites showing major differences. The two most distinct metabolites were 6-methoxy-2-(2-phenylethyl) chromone and 6,7-dimethoxy-2-(2-phenylethyl) chromone. Among the volatile metabolites, 142 showed promising potential in treating insomnia, anxiety, and depression, implicating various biological and signaling pathways, predominantly ALB and TNF targets. The top three active metabolites identified were 2-(2-phenylethyl) chromone, 1,5-diphenylpent-1-en-3-one, and 6-methoxy-2-[2-(4'-methoxyphenyl) ethyl] chromone, with their relative content in the four types of agarwood being TT>HL>CL>BT. Conclusion: The differences in the content of 2-(2-phenylethyl) chromones suggest that they may be responsible for the varying therapeutic activities observed in different types of agarwood aromatherapy. This study offers theoretical support for the selection of agarwood in aromatherapy practices.

Terpenes from Cannabis sativa induce antinociception in a mouse model of chronic neuropathic pain via activation of adenosine A 2A receptors.

Terpenes are small hydrocarbon compounds that impart aroma and taste to many plants, including Cannabis sativa . A number of studies have shown that terpenes can produce pain relief in various pain states in both humans and animals. However, these studies were methodologically limited and few established mechanisms of action. In our previous work, we showed that the terpenes geraniol, linalool, β-pinene, α-humulene, and β-caryophyllene produced cannabimimetic behavioral effects via multiple receptor targets. We thus expanded this work to explore the potential antinociception and mechanism of these Cannabis terpenes in a mouse model of chronic pain. We first tested for antinociception by injecting terpenes (200 mg/kg, IP) into male and female CD-1 mice with mouse models of chemotherapy-induced peripheral neuropathy (CIPN) or lipopolysaccharide-induced inflammatory pain, finding that the terpenes produced roughly equal antinociception to 10 mg/kg morphine or 3.2 mg/kg WIN55,212. We further found that none of the terpenes produced reward as measured by conditioned place preference, while low doses of terpene (100 mg/kg) combined with morphine (3.2 mg/kg) produced enhanced antinociception vs either alone. We then used the adenosine A 2A receptor (A 2A R) selective antagonist istradefylline (3.2 mg/kg, IP) and spinal cord-specific CRISPR knockdown of the A 2A R to identify this receptor as the mechanism for terpene antinociception in CIPN. In vitro cAMP and binding studies and in silico modeling studies further suggested that the terpenes act as A 2A R agonists. Together these studies identify Cannabis terpenes as potential therapeutics for chronic neuropathic pain and identify a receptor mechanism for this activity.

Gasification for material recycling—A solution to the plastic flood?

AbstractSince 1950, only 9% of all plastic produced has undergone recycling, and a mere 10% of that has been recycled multiple times. Most discarded plastic (around 73%) ends up in landfills or is improperly managed, resulting in widespread littering. The main reason for low recycling rates is the lack of recycling technology for multi‐polymer and multi‐layer materials and unsortable mixed plastic waste. This plastic waste is one of the most accumulating types, including for example single‐use food packaging with an average lifetime of less than 6 months. These multi‐layer films, consisting of various polymer types, are not feasible for traditional mechanical recycling, which requires well‐sorted, clean, and homogeneous materials. Several methods for plastic recycling have been proposed to address this issue and tackle the overwhelming influx of plastic waste, among which steam gasification stands out as one of the most promising approaches for recycling mixed, contaminated, and unsortable plastics. This method utilizes high temperatures (800°C) to atomize the plastics, resulting in a gas mixture of , CO, and and small hydrocarbons. The resulting gas can be reformed through hydrocarbon syntheses, for example, via methanol to propylene and ethylene, and successive into new mono‐ and polymers of equal quality to fossil‐based plastics. Moreover, since the high temperatures atomize any organic structure, biomass can be used as a substitute for an extension of the carbon feed, ultimately reducing reliance on fossil feedstock. With these advantages, steam gasification can significantly increase recycling rates and contribute to a bio‐integrated circular carbon economy.

Simultaneous measurement of multi-component gases from pyrolysis of hydrocarbon fuels using absorption spectroscopy

Endothermic hydrocarbon fuel is cracked into small hydrocarbons at high temperatures. Quantitative analysis of the pyrolysis product’s component concentration is of great significance for the analysis of engine combustion regenerative cooling technology and combustion efficiency. Off-axis integrated cavity output spectroscopy technique was adopted in laser absorption spectroscopy. Using the near-infrared spectroscopic properties of methane and ethylene, the component concentrations of methane and ethylene at different temperatures and cracking times were measured. In addition, a high temperature kerosene pyrolysis spectrum measurement system was built, and a concentration measurement error of not more than 3.2 % was achieved. Pyrolysis experiment shows that at low temperatures and short heating times, the concentration of the components that crack methane and ethylene is low. Ethylene is the first to crack as the temperature rises, and it accounts for a relativity large proportion of the mixture. Other gases crack out with the increase of the cracking time. The component concentration of ethylene is basically stable at approximately 12 %.

Proximity effects: Structural implications and quantum-chemical description. Review

Proximity effects occur between vicinal functional groups or between a group and a specific molecular fragment in close proximity, for example an endocyclic N atom in the ortho position relative to the group. They are a combination of through-bond inductive and resonance effects, and through-space interactions, which can be either attractive or repulsive. In this review, we discuss quantum-chemical tools and examples from the literature that explore the structural and physicochemical implications of proximity effects. We focus on derivatives of small molecules: benzene, small polycyclic aromatic hydrocarbons, simple heterocycles, and lastly, purine derivatives.

What is the Initiating Reaction for the Lipid Radical Chain Reaction System That Can Induce Ferroptotic Cell Death at the Lower Oxygen Content?

The neural cell death in cerebral infarction is suggested to be ferroptosis-like cell death, involving the participation of 15-lipoxygenase (15-LOx). Ferroptosis is induced by lipid radical species generated through the one-electron reduction of lipid hydroperoxides, and it has been shown to propagate intracellularly and intercellularly. At lower oxygen concentration, it appeared that both regiospecificity and stereospecificity of conjugated diene moiety in lipoxygenase-catalysed lipid hydroperoxidation are drastically lost. As a result, in the reaction with linoleic acid, the linoleate 9-peroxyl radical-ferrous lipoxygenase complex dissolves into the linoleate 9-peroxyl radical and ferrous 15-lipoxygenase. Subsequently, the ferrous 15-lipoxygenase then undergoes one-electron reduction of 13-hydroperoxy octadecadienoic acid, generating an alkoxyl radical (pseudoperoxidase reaction). A part of the produced lipid alkoxyl radicals undergoes cleavage of C-C bonds, liberating small molecular hydrocarbon radicals. Particularly, in ω-3 polyunsaturated fatty acids, which are abundant in the vascular and nervous systems, the liberation of small molecular hydrocarbon radicals was more pronounced compared to ω-6 polyunsaturated fatty acids. The involvement of these small molecular hydrocarbon radicals in the propagation of membrane lipid damage is suggested.

Hydrogels based on crosslinked polyethylene glycol diacrylate and fish skin gelatin

The aim of this work was to develop hydrogels based on poly(ethylene glycol diacrylate) (PEGDA) and fish gelatin for potential biomedical applications such as wound healing, drug delivery and biosensors. The hydrogels were prepared via in situ Michael addition of ammonia crosslinker to PEGDA in the presence of cold-water fish skin gelatin that was used as an additive. The fabrication conditions and properties of the hydrogels were examined using various amounts of fish gelatin to evaluate the influence of its concentration on gelation time, crosslinking density and swelling behavior of the hydrogels. FTIR spectra confirmed the formation of the crosslinked hydrogels and the degree of conversion (DC) of the double bonds for the hydrogels containing 5, 7.5 and 10 % w/v of gelatin was between 72 and 80 %. Fish skin gelatin had a strong effect on the dimentional stability and water absorbing properties of the hydrogels and the system containing 7.5 % w/v gelatin exhibited the longest swelling time of 18 h. The hydrophobicity of the hydrogels was achieved by covalent grafting of the residual double bonds with thiol-containing small hydrocarbon molecules using thiol-ene click chemistry reaction conditions, leading to the increase of the water contact angle from 0° to 60-73°.