Oxidation Products Research Articles

Mercaptan removal with electroscrubbing pilot

A new electroscrubbing technology has been developed. This Power-to-X process utilizes active chlorine, which oxidizes impurities and is continuously regenerated in an electrochemical cell. The process is primarily intended for hydrogen sulfide capture, but has shown potential in removing other sulfur components as well. In this paper the capability of the process for removing methyl mercaptan has been examined.The electroscrubbing process was able to remove mercaptan to undetectable levels. The capture rate of mercaptan was primarily determined by the applied electrical current. Gas flow and concentration had a negligible effect on the capture while liquid flow had only a minor impact.The primary product of the mercaptan oxidation was found to be sulfate ions.

Photoaged polystyrene nanoplastics exposure results in reproductive toxicity due to oxidative damage in Caenorhabditis elegans

The increase of plastic production together with the incipient reuse/recycling system has resulted in massive discards into the environment. This has facilitated the formation of micro- and nanoplastics (MNPs) which poses major risk for environmental health. Although some studies have investigated the effects of pristine MNPs on reproductive health, the effects of weathered MNPs have been poorly investigated. Here we show in Caenorhabditis elegans that exposure to photoaged polystyrene nanoplastics (PSNP-UV) results in worse reproductive performance than pristine PSNP (i.e., embryonic/larval lethality plus a decrease in the brood size, accompanied by a high number of unfertilized eggs), besides it affects size and locomotion behavior. Those effects were potentially generated by reactive products formed during UV-irradiation, since we found higher levels of reactive oxygen species and increased expression of GST-4 in worms exposed to PSNP-UV. Those results are supported by physical-chemical characterization analyses which indicate significant formation of oxidative degradation products from PSNP under UV-C irradiation. Our study also demonstrates that PSNP accumulate predominantly in the gastrointestinal tract of C. elegans (with no accumulation in the gonads), being completely eliminated at 96 h post-exposure. We complemented the toxicological analysis of PSNP/PSNP-UV by showing that the activation of the stress response via DAF-16 is dependent of the nanoplastics accumulation. Our data suggest that exposure to the wild PSNP, i.e., polystyrene nanoplastics more similar to those actually found in the environment, results in more important reprotoxic effects. This is associated with the presence of degradation products formed during UV-C irradiation and their interaction with biological targets.

Extension, development, and evaluation of the representation of the OH-initiated dimethyl sulfide (DMS) oxidation mechanism in the Master Chemical Mechanism (MCM) v3.3.1 framework

Abstract. Understanding dimethyl sulfide (DMS) oxidation can help us constrain its contribution to Earth's radiative balance. Following the discovery of hydroperoxymethyl thioformate (HPMTF) as a DMS oxidation product, a range of new experimental chamber studies have since improved our knowledge of the oxidation mechanism of DMS and delivered detailed chemical mechanisms. However, these mechanisms have not undergone formal intercomparisons to evaluate their performance. This study aimed to synthesise the recent experimental studies and develop a new, near-explicit, DMS mechanism, through a thorough literature review. A simple box model was then used with the mechanism to simulate a series of chamber experiments and evaluated through comparison with four published mechanisms. Our modelling shows that the mechanism developed in this work outperformed the other mechanisms on average when compared to the experimental chamber data, having the lowest fractional gross error for 8 out of the 14 DMS oxidation products studied. A box model of a marine boundary layer was also run, demonstrating that the deviations in the mechanisms seen when comparing them against chamber data are also prominent under more atmospherically relevant conditions. Although this work demonstrates the need for further experimental work, the mechanism developed in this work has been evaluated against a range of experiments, which validate the mechanism and reduce the bias from individual experiments. Our mechanism provides a good basis for a near-explicit DMS oxidation mechanism that would include other initiation reactions (e.g. halogens) and can be used to compare the performance of reduced mechanisms used in global models.

Incomplete lipid extraction as a possible cause for underestimation of lipid oxidation in emulsions

AbstractLipid oxidation deteriorates the sensory and nutritional quality of food emulsions containing polyunsaturated fatty acids. Classically, different extraction solvents are used as a first step to measure lipid oxidation in emulsions. However, it is unclear how the applied extraction method influences the measured lipid oxidation values. In this work, we systematically examined the performance of common solvent mixtures such as chloroform, methanol, and hexane (or isooctane)–isopropanol on lipid extraction from emulsions stabilized with different emulsifiers (Tween 20 (T20), whey proteins, and pea proteins) and oxidation levels, and how this, in turn, affected the measured hydroperoxide concentrations. Chloroform–methanol was the most effective solvent (lipid yield >93 wt.%). When using hexane–isopropanol, extraction yields were consistently high for T20‐ and pea protein‐based emulsions (>60 wt.%), but in whey protein‐based emulsions, values as low as 26 wt.% were measured. In case of incomplete extraction, hydroperoxide concentrations measured by colorimetric methods need to be corrected for this effect. When using 1H NMR to assess lipid oxidation, the actual amount of extracted lipids is intrinsically taken into account. This highlights not only the importance of the extraction method in determining lipid oxidation in emulsions but also that of the actual analysis method.Practical application: This study highlights that the lipid extraction yield can vary depending not only on the emulsion composition (e.g., type of emulsifier) but also on the oxidative state of the emulsion and the extraction solvent used. If this is overlooked, errors can be made in the hydroperoxide determination. Although these effects can be corrected for, this is not standard procedure, which implies that awareness on this matter should be increased. It is also important to point out that depending on the solvent used, the different lipid classes (including various lipid oxidation products) may be extracted at different levels. Chloroform–methanol should be preferred for extraction of all lipid and lipid oxidation‐derived molecules, including aldehydes.

Hydrothermal depolymerization of spent biomass for production of lactic acid and small aromatics

Lactic acid synthesis from lignocelluloses can respond to the environmental concerns associated with producing this important commodity chemical for various applications, e.g., food, cosmetics, pharmaceuticals, etc. Pretreatment of palmarosa (Cymbopogon martinii) biomass with 1.0 % HNO3 solution at 121 °C temperature and 1.03 bar pressure for 60 min under an autoclave conditions demonstrated a highly selective conversion of biomass contained hemicellulose to xylose in ∼17 wt % yield. A further hydrolytic depolymerization of pretreated biomass to liquid products was carried out via processing in the presence of anthraquinone (5 wt % loading) as a catalyst under temperature (250 °C) and pressure (15–16 bar, where, 1 bar = 105 Pa) in dilute NaOH (1.5 M) solution for 60 min to afford a hydrolysate rich in carboxylic acids and small aromatics. Solvent extraction method was applied successfully to separate the aromatic compounds from the aqueous phase. The carboxylic acids were formed as the product of cellulose oxidation with good selectivity (>45 %) towards the DL-lactic acid (∼14 wt % yield with respect to substrate biomass). Small aromatics, predominantly phenol was identified as the product of depolymerized lignin.

Exploring the peroxydisulfate activation by carbon nanotubes for pollutants degradation: Identification of the primary reaction mechanism and key molecular descriptor

Carbon nanotubes (CNT) have been proposed to activate persulfate over the past decade, resulting in successful degradation performance for organic pollutants in wastewater treatment. However, there is debate over the reaction mechanism involving radical versus non-radical pathways, setting up a roadblock to further developing persulfate activation by carbonaceous materials. This work focused on the carbon nanotubes/peroxydisulfate (CNT/PDS) system, investigated its reaction mechanism, and unveiled the relationship from the aspect of molecular descriptors. The involvement of radicals (e.g., SO4•− and HO•) and 1O2 was ruled out by the observation of quenching effect, oxidation products, chemical probes, solvent exchange, and electron paramagnetic resonance spectra. Then, mediated electron transfer was deemed as the primary reaction mechanism based on linear sweep voltammetry analysis, which was supported by the PDS consumption result. The substrate-dependent treatment capacity was found in the CNT/PDS for multiple contaminants degradation, and it turned out that EB3LYP was the most significant parameter in the relationship between degradation rates and molecular descriptors. Outstanding environmental application was exhibited based on the coexistence of various organic/inorganic substances and repeated degradation experiment. Therefore, the findings from this study would be helpful for both scientific research and technical development of persulfate activation by CNT.

Measurement report: Atmospheric ice nuclei in the Changbai Mountains (2623 m a.s.l.) in northeastern Asia

Abstract. Atmospheric ice nucleation plays an important role in modulating the global hydrological cycle and atmospheric radiation balance. To date, few comprehensive field observations of ice nuclei have been carried out at high-altitude sites, which are close to the height of mixed-phase cloud formation. In this study, we measured the concentration of ice-nucleating particles (INPs) in the immersion freezing mode at the summit of the Changbai Mountains (2623 m above sea level), northeast Asia, in summer 2021. The cumulative number concentration of INPs varied from 1.6 × 10−3 to 78.3 L−1 over the temperature range of −5.5 to −29.0 °C. Proteinaceous-based biological materials accounted for the majority of INPs, with the proportion of biological INPs (bio-INPs) exceeding 67 % across the entire freezing-temperature range, with this proportion even exceeding 90 % above −13.0 °C. At freezing temperatures ranging from −11.0 to −8.0 °C, bio-INPs were found to significantly correlate with wind speed (r = 0.5–0.8, p < 0.05) and Ca2+ (r = 0.6–0.9), and good but not significant correlation was found with isoprene (r = 0.6–0.7) and its oxidation products (isoprene × O3) (r = 0.7), suggesting that biological aerosols may attach to or mix with soil dust and contribute to INPs. During the daytime, bio-INPs showed a positive correlation with the planetary boundary layer (PBL) height at freezing temperatures ranging from −22.0 to −19.5 °C (r > 0.7, p < 0.05), with the valley breezes from southern mountainous regions also influencing the concentration of INPs. Moreover, the long-distance transport of air mass from the Japan Sea and South Korea significantly contributed to the high concentrations of bio-INPs. Our study emphasizes the important role of biological sources of INPs in the high-altitude atmosphere of northeastern Asia and the significant contribution of long-range transport to the INP concentrations in this region.

Lipidomics analysis unveils the dynamic alterations of lipid degradation in rice bran during storage

Recent explorations into rice bran oil (RBO) have highlighted its potential, owing to an advantageous fatty acid profile in the context of health and nutrition. Despite this, the susceptibility of rice bran lipids to oxidative degradation during storage remains a critical concern. This study focuses on the evolution of lipid degradation in RBO during storage, examining the increase in free fatty acids (FFAs), the formation of oxylipids, and the generation of volatile secondary oxidation products. Our findings reveal a substantial rise in FFA levels, from 109.55 to 354.06 mg/g, after 14 days of storage, highlighting significant lipid deterioration. Notably, key oxylipids, including 9,10-EpOME, 12,13(9,10)-DiHOME, and 13-oxoODE, were identified, with a demonstrated positive correlation between total oxylipids and free polyunsaturated fatty acids (PUFAs), specifically linoleic acid (LA) and α-linolenic acid (ALA). Furthermore, the study provides a detailed analysis of primary volatile secondary oxidation products. The insights gained from this study not only sheds light on the underlying mechanisms of lipid rancidity in rice bran but also offers significant implications for extending the shelf life and preserving the nutritional quality of RBO, aligning with the increasing global interest in this high-quality oil.

Exploring the Complex Impact of Proteins on Dopamine Polymerization: Mechanisms and Strategies for Modulation.

Polydopamine (pDA) is a valuable material with wide-ranging potential applications. However, the complex and debated nature of dopamine polymerization complicates our understanding. Specifically, the impact of foreign substances, especially proteins, on pDA formation adds an additional layer of subtlety and complexity. This study delves into specific surface features of proteins that predominantly shape their impact on dopamine polymerization. Notably, the biotin-binding site emerges as a critical region responsible for the pronounced inhibitory effect of avidin and neutravidin on the dopamine polymerization process. The binding of biotin successfully mitigates these inhibitory effects. Moreover, several nucleases demonstrated a significant hindrance to pDA formation, with their impact substantially alleviated through the introduction of DNA. It is speculated that hydrogen bonding, electrostatic, cation-π, and/or hydrophobic interactions may underlie the binding between protein surfaces and diverse oligomeric intermediates formed by the oxidation products of dopamine. Additionally, we observed a noteworthy blocking effect on the dopamine polymerization reaction induced by erythropoietin (EPO), a glycoprotein hormone known for its role in stimulating red blood cell production and demonstrating neuroprotective effects. The inhibitory influence of EPO persisted even after deglycosylation. These findings not only advance our comprehension of the mechanisms underlying dopamine polymerization but also provide strategic insights for manipulating the reaction to tailor desired biomaterials.

Boosting photocatalytic hydrogen peroxide evolution through aerobic oxidative dehydrogenation of benzyl alcohol over amino acid hyper-cross-linked polymer in two-phase system

The fusion of photocatalytic hydrogen peroxide (H2O2) production with the generation of high-value organic compounds carries the potential to optimize the utilization of solar energy. The efficient generation and separation of products constitute indispensable elements in constructing a proficient reaction system. Herein, the photocatalytic production of H2O2 via the aerobic oxidative dehydrogenation of benzyl alcohol (BA) was realized through the application of an amino acid hyper-cross-linked polymer (H6P-HCPs) in two-phase system. The outcomes unveiled that the H6P-HCPs with 1:6 M ratio of L-phenylalanine (L-Phe) and hexaphenylbenzene (HPB) achieves the highest generation rate of H2O2 (29.26 mmol∙gcat-1∙h-1), stoichiometric amount of benzyl alcohol oxidation products were obtained as 96% benzaldehyde (23.94 mmol∙gcat-1∙h-1) and 4% benzoic acid (5.56 mmol∙gcat-1∙h-1). Time-dependent density functional theory (TDDFT) calculations illuminated that the presence of L-Phe monomers of H6P-HCPs not only facilitated electron transfer from L-Phe to HPB, capitalizing on electronegativity differentials, but also instigated the formation of O2•- while concurrently adjusting its hydrophobic nature. These factors, in concert, were instrumental in the accomplishment of this highly efficient photocatalytic process.

Influence of updated isoprene oxidation mechanisms on the formation of intermediate and secondary products in MCM v3.3.1

In this study, we developed an observation based photochemical box model with the measurement data collected at a suburban site (i.e., the Xianghe, XH site) of the Beijing-Tianjin-Hebei (BTH) region and the latest version of the Master Chemical Mechanism (MCM v3.3.1), which newly incorporated 498 reaction for the additional 155 species with the oxidation of isoprene by the OH radical. The influence of updated isoprene degradation on the radical budgets, formation of intermediate and secondary products by comparing the simulation results in the original version (MCM v3.2) was firstly analyzed to estimate whether the updates of precursors could influence the model performance on its evolution pathways and related products. The results demonstrated that though the input of isoprene could significantly decrease or increase the concentrations of OH and HO2 radicals in the model simulation, respectively, the difference in the simulated concentrations of these radicals with isoprene oxidation before and after the updates was not statistically significant. For intermediate products, the simulated concentrations of formaldehyde and methacrolein (MACR) did not significantly alter before and after the updates, while the abundance of methyl vinyl ketone (MVK) reduced obviously (the maximum reduction of 31%) due to lower reaction coefficient between ISOPBO2 and NO and the lower branching ratios caused by the newly added pathways involving CISOPA and TISOPA in the updated scheme. On the other hand, the simulation concentrations of acrolein (ACR), glyoxal (Gly) and methylglyoxal (Mgly) increased significantly after the model updates. The dominant pathway for the increment of ACR was the decomposition of CH2CHCH2O produced by PE4E2CO, while those of Gly and Mgly were associated with radicals of C537O and PACLOOA that were both from the new intermediate radical of CISOPC. In addition, 39 isoprene oxidation products among the 155 new added species were identified to partition in the formation of secondary organic aerosol (SOA), which were coupled in the gas-particle partitioning module to optimize the formation of SOA, contributing 1.15 μg m−3 to the increase of SOA mean concentration. The updates of isoprene degradation further resulted in the significant change for its sensitivity in SOA formation, making it as the secondary important SOA precursor at the XH site. Last but not the least, the influence on photochemical ozone formation related to updates of isoprene degradation was ignorable. Overall, the above results confirmed the insufficient description of the degradation of precursors indeed limited the simulation of the intermediate and secondary products, highlighting the needs of exploring and parameterizing the precursor degradation processes for better understanding of their behaviors and SOA formation in the atmosphere.

In-Canopy Chemistry, Emissions, Deposition, and Surface Reactivity Compete to Drive Bidirectional Forest-Atmosphere Exchange of VOC Oxidation Products

In-Canopy Chemistry, Emissions, Deposition, and Surface Reactivity Compete to Drive Bidirectional Forest-Atmosphere Exchange of VOC Oxidation Products

Insight into the dynamic change of flavor profiles and their correlation with microbial community succession and lipid oxidation during the processing of dry-cured duck

Microbial community and lipid oxidation play an important role in flavor development of dry-cured duck. To explore the dynamic changes in microbial community succession, oxidative properties and flavor profiles during the processing of dry-cured duck and the relationships between them, the samples were analyzed by high-throughput sequencing, peroxide values, electronic nose and gas chromatography-mass spectrometry, and their relationships were established by multivariate statistical analysis. The results showed that the changes in lipid oxidation were related to the processing technology, especially the air-drying time. Thirty-five volatiles were identified, of which nonanal, 1-octen-3-ol, hexanal, benzaldehyde, and 2-pentylfuran were the characteristic aroma compounds. Staphylococcus, Vibrio, and Lactococcus were the dominant genera during the processing. Staphylococcus and Lactococcus were positively correlated with the characteristic flavor compounds and lipid oxidation products. These findings offer novel insights into the flavor formation of dry-cured ducks and offer deeper theoretical guidance for their preparation and production.

Upcycle polyethylene terephthalate waste by photoreforming: Bifunction of Pt cocatalyst

Upcycle polyethylene terephthalate (PET) waste by photoreforming (PR) is a sustainable and green approach to tackle environmental problems but with challenges to obtain valuable oxidation products and high purity hydrogen simultaneously. Noble metal cocatalysts are essential to enhance the overall PR reaction efficacy. In this work, TiO2 nanotubes (TiO2 NTs) decorated with single Pt atoms (Pt1/TiO2) or Pt nanoparticles (PtNPs/TiO2) are used in the photoreforming reaction (in one batch), and the oxidation products from ethylene glycol (EG, hydrolysed product of PET) in liquid phase and hydrogen are detected. With Pt1/TiO2, EG is oxidized to glyoxal, glyoxylate or lactate, and hydrogen evolution rate (r H2) reaches 51.8 μmol⋅h−1⋅gcat−1, that is 30 times higher than that of TiO2. For PtNPs/TiO2 (size of Pt NPs: 1.97 nm), hydrogen evolution reaches 219.1 μmol⋅h−1⋅gcat−1, but with the oxidation product of acetate only. DFT calculation demonstrates that for Pt NPs, the reaction path for hydrogen evolution is preferred thermodynamically, due to the formation of Schottky junction. On the oxidation of EG, theoretical and spectroscopic analysis suggest that bidentate adsorption of EG at the interface is facile on Pt1/TiO2, compared to that on PtNPs/TiO2 (two Pt sites), but oxidation products, adsorb less strongly, compared to PtNPs/TiO2, that eventually regulates the distribution of oxidation products. The results thus demonstrate the bifunctions of Pt in the PR reaction, i.e., electron transfer mediator for hydrogen evolution and reactive sites for molecules adsorption. The oxidation reaction is dominated by the adsorption-desorption behavior of molecules but the reduction reaction is controlled by the electron transfer. In addition, acidification of pretreated PET alkaline solution achieves separation of pure terephthalic acid (PTA), which further improves the reaction efficiency possibly by offering high density of active sites and acidic environment. Our work thus demonstrates that to upcycle PET plastics, an optimized process can be reached by atomic design of photocatalysts and proper treatment on the plastic wastes.

Metabolites rapid-annotation in mice by comprehensive method of virtual polygons and Kendric mass loss filtering: A case study of Dendrobium nobile Lindl

With significant advancements in high-resolution mass spectrometry, there has been a substantial increase in the amount of chemical component data acquired from natural products. Therefore, the rapid and efficient extraction of valuable mass spectral information from large volumes of high-resolution mass spectrometry data holds crucial significance. This study illustrates a targeted annotation of the metabolic products of alkaloid and sesquiterpene components from Dendrobium nobile (D. nobile) aqueous extract in mice serum through the integration of an in-houses database, R programming, a virtual metabolic product library, polygonal mass defect filtering, and Kendrick mass defect strategies. The research process involved initially establishing a library of alkaloids and sesquiterpenes components and simulating 71 potential metabolic reactions within the organism using R programming, thus creating a virtual metabolic product database. Subsequently, employing the virtual metabolic product library allowed for polygonal mass defect filtering, rapidly screening 1705 potential metabolites of alkaloids and 3044 potential metabolites of sesquiterpenes in the serum. Furthermore, based on the chemical composition database of D. nobile and online mass spectrometry databases, 95 compounds, including alkaloids, sesquiterpenes, and endogenous components, were characterized. Finally, utilizing Kendrick mass defect analysis in conjunction with known alkaloids and sesquiterpenes targeted screening of 209 demethylation, methylation, and oxidation products in phase I metabolism, and 146 glucuronidation and glutathione conjugation products in phase II metabolism. This study provides valuable insights for the rapid and accurate annotation of chemical components and their metabolites in vivo within natural products.

The effect of gamma radiation on 5-hydroxymethylfurfural conversion in water and dimethyl sulfoxide

Abstract 5-Hydroxymethylfurfural (HMF) is a biomass-based chemical platform that can undergo many feasible reactions. One of the most important reactions is the oxidation to 2,5-furandicarboxylic acid (FDCA), which is the monomer for bioplastic production. In this work, the radiation method was used to investigate the conversion of HMF in both aqueous (DI) and dimethyl sulfoxide (DMSO) solutions. The effects of media solvents, atmospheric gases, HMF concentrations, additive bases, and absorbed doses of gamma radiation were studied. The results showed that the media solvent played a crucial role in HMF conversion under gamma irradiation. At 30 kGy, the HMF conversions in DI and DMSO were 92.1 and 24.1%, respectively, and the oxidation products were only found in the irradiated samples under DMSO. The HMF conversion and oxidation product formation increased with the gamma radiation dose. Moreover, it was found that FDCA stability toward gamma irradiation is highly sensitive in aqueous solution but relatively stable in DMSO. The results implied the alternative promising choice of radiation method compared with traditional methods. To join the bridge, the use of a mixture solvent DI/DMSO seems considerable in the future.

Sulfur poisoning-resistant TiO2/Cu-doped ZnIn2S4 photoanode for achieving efficient sulfur oxidation

Ternary ZnIn2S4 is a layered metal sulfide and suitable for catalyzing H2S-containing industrial waste streams due to its excellent light absorption in the visible region. However, imperfect electrical conductivity and slow surface reaction lead to severe internal intrinsic charge recombination. For this reason, we modify pristine ZnIn2S4 by synergistic coordination of heterojunction and doping. The TiO2/0.6 ml Cu2+-ZIS sample achieves a photocurrent density of 2.87 mA/cm2, which is 8.2 times higher than that of pure ZnIn2S4. Investigation of the surface states (SS) shows that the improved performance results from an increase in the density of available surface states as well as the consistency of the surface state center potential with the S/H2S oxidation potential. This is the new attempt to analyze the photoelectrocatalytic (PEC) behavior of the sulfur oxidation reaction using surface state theory. The results of catalytic product resolution and data from theoretical calculations indicate that the timely desorption of polysulfide ions at Cu2+ sites and the solubility of the only oxidation product (S2O32-), are the reasons for maintaining high performance after 4 h stability testing. This study not only gives a new reference for the modification strategy of ZnIn2S4 but also a new solution for catalyst S poisoning.

A sensitive GC-MS/MS method for the quantification of benzo[a]pyrene tetrol in urine.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants formed during the incomplete combustion of organic matter such as tobacco. Among these, benzo[a]pyrene (BaP) has been classified as a known carcinogen to humans. It unfolds its effect through metabolic activation to BaP-(7R,8S)-diol-(9S,10R)-epoxide (BPDE), the ultimate carcinogen of BaP. In this article, we describe a simple and highly sensitive GC-NICI-MS/MS method for the quantification of urinary BaP-(7R,8S,9R,10S)-tetrol (( +)-BPT I-1), the hydrolysis product of BPDE. The method was validated and showed excellent results in terms of accuracy, precision, and sensitivity (lower limit of quantification (LLOQ): 50pg/L). In urine samples derived from users of tobacco/nicotine products and non-users, only consumption of combustible cigarettes was associated with a significant increase in BPT I-1 concentrations (0.023 ± 0.016nmol/mol creatinine, p < 0.001). Levels of users of potentially reduced-risk products as well as non-users were all below the LLOQ. In addition, the urine levels of six occupationally exposed workers were analyzed and showed the highest overall concentrations of BPT I-1 (844.2 ± 336.7pg/L). Moreover, comparison with concentrations of 3-hydroxybenzo[a]pyrene (3-OH-BaP), the major detoxification product of BaP oxidation, revealed higher levels of 3-OH-BaP than BPT I-1 in almost all study subjects. Despite the lower levels, BPT I-1 can provide more relevant information on an individual's cancers susceptibility since BPDE is generated by the metabolic activation of BaP. In conclusion, BPT I-1 is a suitable biomarker to distinguish not only cigarette smokers from non-smokers but also from users of potentially reduced-risk products.

First-Principles Investigation on the Adsorption and Diffusion of Oxygen at the B2(110)–O(001) Interface in Ti2AlNb Alloys

The adsorption and diffusion of oxygen at the B2(110)[1¯11]||O(001)[11¯0] interface in Ti2AlNb alloys were investigated via first-principles calculations. Only a 2.6% interfacial mismatch indicates that B2(110)–O(001) is basically a stable coherent interface. The calculated adsorption energies and diffusion energy barriers show that oxygen prefers to occupy the Ti-rich interstitial sites, and once trapped, it hardly diffuses to other interstitial sites, thus promoting the preferential formation of Ti oxides. Under the premise of a Ti-rich environment, a Nb-rich environment is more favorable for oxygen adsorption than an Al-rich environment. The electronic structures suggest that O 2p orbitals mainly occupy the energy region below −5 eV, bonding with its coordinated atoms of Ti, Al, and Nb. However, Al 3p and Nb 4d orbitals near the Fermi level couple with sparsely distributed O 2p orbitals, forming anti-bonding, which is not conducive to oxygen adsorption. Because Nb 4d electrons are more localized than Al 3p electrons are, Nb–O anti-bonding is weaker. O–Ti has almost no contribution to anti-bonding, suggesting good bonding between them. This is consistent with the experimental observations that TiO2 is the main oxidation product.

A new perspective for palladium(II)-catalyzed alcohol oxidation in aerobic means

The development of alternative and environmentally safe routes for the oxidation of primary and secondary alcohols has attracted the attention of several researchers due to the importance of these oxidized products in industries. Thereby, the oxidation of β-citronellol, geraniol, nerol, borneol, isoborneol, cinnamic alcohol, and benzyl alcohol is described herein. These reactions occurred in an aerobic environment, with or without system pressurization. Acetonitrile was the solvent used. The process was catalyzed by the bimetallic complex formed with palladium(II) acetate and copper(II) acetate, using p-benzoquinone as a cocatalyst in some reaction conditions. The applied system obtained 62.5 points on the eco-scale, with yields above 61%. Alcohol oxidation products are of great importance in industrial applications. Thus, this work presents a cleaner, more sustainable alternative to alcohol oxidations.