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The potential for ammonia/hydrogen (NH 3 /H 2) blends as fuel in modern, turbocharged, gas engines is evaluated by comparing the combustion properties of these blends with those of methane. To ensure proper combustion phasing in existing spark-ignited (SI) engines, the laminar burning velocity (LBV) is used, while the ignition delay times (IDT) of the mixtures are compared to assess the risk of engine knock. The chemical mechanisms used for the computation of IDT and/or LBV of NH 3 /H 2 mixtures are selected from 8 chemical mechanisms based on their ability to predict experimental data. The application of a turbocharger is shown to "boost" the temperature in the cylinder after compression to values that admit the use of NH 3 /H 2 mixtures in natural-gas SI engines without increasing the compression ratio (CR). The analysis also identifies regions of temperature and H 2 fraction that increase the risk of knock. Using the conditions in a practical turbocharged SI engine as an example, 40–50% H 2 in NH 3 yields combustion phasing equivalent to that obtained with methane, while avoiding the risk of knock. Analysis of the IDT for the conditions in a high-pressure direct-injection natural-gas engine also shows that the use of a turbocharger in compression-ignition (diesel-type) engines strongly reduces the demands on CR for achieving the conditions necessary for reliable ignition of NH 3 /H 2 mixtures. Increasing the temperature by only a few tens of degrees above the conditions studied will yield an IDT for ∼20% H 2 in NH 3 that satisfies the ignitibility requirements for use in a turbocharged diesel engine. • Turbocharging facilitates the use of NH 3 /H 2 mixtures in gas engines. • The risk of engine knock limits the "boost" temperature and maximum H 2 fraction. • 40–50% H 2 in NH 3 mimics CH 4 combustion without knocking in the SI engine considered. • Modest preheating enables the use of NH 3 with 20% H 2 in a turbocharged CI engine. • The methodology used is readily applied to different fuels and engine conditions. [ABSTRACT FROM AUTHOR]

Volatile organic compound (VOC) emissions to the atmosphere cause air pollution associated with adverse health outcomes. Volatile chemical products (VCPs) have emerged as a VOC emission category that is poorly characterized by air pollution models. VCPs are present throughout developed economies in manufactured products that include paints, cleaning agents, printing inks, adhesives and pesticides. Air quality models must accurately represent the atmospheric chemistry of VCPs to develop reliable air quality plans. We develop a chemical mechanism for oxidant formation by VCP compounds that is compatible with version 6 of the Carbon Bond (CB6) mechanism. We analyzed a recent U.S. VCP emission inventory and found that ~67% of the emissions mass can be well-represented by existing CB6 mechanism species but ~33% could be better represented by adding 16 emitted VCP species including alcohols, ethers, esters, alkanes and siloxanes. For larger alkanes, an important VCP category, our mechanism explicitly represents temperature-dependent organic nitrate formation and autoxidation via 1,6 H-shift reactions consistent with current knowledge. We characterized the ozone forming potential of each added VCP species and compared it to the current practice of representing VCP species by surrogate species. Nine of the sixteen added VCP species are less reactive than the current practice, namely i-propanol, dimethyl ether, methyl formate, ethyl formate, methyl acetate, larger esters, i-butane, large alkanes and siloxanes. These less reactive VCP species are characterized by having OH-reactions that form un-reactive products. A total of 7 of the 16 VCP species are more reactive than current practice, namely n-propanol, ethylene glycol, propylene glycol, larger alcohols, diethyl ether, larger ethers and ethyl acetate. These more reactive VCP species are characterized as containing functional groups that promote faster OH-reaction. The VCP chemical mechanism for CB6 can improve how VCP impacts to oxidants are represented and will be incorporated to CB7. Changes in oxidant formation resulting from the mechanism update will depend on how VCP emissions are speciated for modeling, which is uncertain, and impacts may go in opposite directions for specific categories of VCP emissions that have unique chemical speciation characteristics. We provide guidance to help modelers implement the VCP mechanism update. [ABSTRACT FROM AUTHOR]

• A smog chamber was designed and comprehensively characterized. • The wall loss of gases and particles are smaller than other chambers. • The chamber can provide high quality data for gas-phase oxidation and SOA formation. Smog chambers provide a potent approach to explore the secondary organic aerosol formation under varied conditions. This study describes the construction and characterization of a new smog chamber facility for studying the formation mechanisms of gas-phase products and secondary organic aerosol from the photooxidation of volatile organic compounds. The chamber is a 5.4 m3 Fluorinated Ethylene Propylene (FEP) Teflon reactor with the potential to perform photooxidation experiments at controlled temperature and relative humidity. Detailed characterizations were conducted for evaluation of stability of environmental parameters, mixing time, background contamination, light intensity, and wall losses of gases and particles. The photolysis rate of NO 2 (J NO2) ranged from (1.02−3.32) ×10−3 sec−1, comparable to the average J NO2 in ambient environment. The wall loss rates for NO, NO 2 , and O 3 were 0.47 × 10−4, 0.37 × 10−4, and 1.17 × 10−4 min−1, while wall loss of toluene was obsoletely found in a 6 hr test. The particle number wall loss rates are (0.01−2.46) ×10−3 min−1 for 40−350 nm with an average lifetime of more than one day. A series of toluene photooxidation experiments were carried out in absence of NO x under dry conditions. The results of the simulation experiments demonstrated that the chamber is well designed to simulate photolysis progress in the atmosphere. [Display omitted] [ABSTRACT FROM AUTHOR]

A small proportion of nephropathy patients administered gadolinium contrast agents for nuclear magnetic resonance have been reported to develop nephrogenic systemic fibrosis (NSF). This paper introduces the mechanism of the transformation and deposition of NSF, aiming to reveal the chemical nature of the gadolinium phosphate bioparticles in nephrogenic system fibrosis. This research will provide an important theoretical basis for future studies on the occurrence, development, and formation of nephrogenic system fibrosis and the removal of sediment residues. Moreover, a new idea for introducing a biocompatible second chelating agent into the gadolinium contrast agent system has been proposed, which aims to improve the safe use of gadolinium contrast agent. [ABSTRACT FROM AUTHOR]

BACKGROUND: Shale gas oil‐based drill cuttings are receiving increasing attention because of their hazards and contamination. In this study, two catalysts (Fe2(SO4)3 and a synthesised catalyst) were used to study the pyrolysis products, possible reaction mechanisms, and kinetic characteristics via thermogravimetry‐mass spectrometry (TG‐MS) analysis. RESULTS: The results indicate that the synthesised catalyst, YAP‐3, exhibited an improved catalytic effect on the pyrolysis of drill cuttings with a good conversion rate. The reaction activation energy during the pyrolysis was reduced from 9.6 to 1.4 kJ/mol. In addition to hydrocarbons, the pyrolysis products contained nitrogen oxides and other compounds. CONCLUSION: A comparison of the peak temperature range and response intensity of the same substance with the same mass‐to‐charge ratio (m/z) showed that YAP‐3 significantly promoted the formation of pyrolysis products. This study provides theoretical support for the catalytic pyrolysis treatment of shale gas drill cuttings. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The flavoenzyme glycolate oxidase oxidizes glycolic acid to glyoxylate and the latter, more slowly, to oxalate. It is a member of an FMN‐dependent enzyme family that oxidizes l‐2‐hydroxy acids to keto acids. There has been a controversy concerning the chemical mechanism of substrate oxidation by these enzymes. Do they proceed by hydride transfer, as observed for NAD‐dependent enzymes, or by initial formation of a carbanion that transfers the electrons to the flavin? The present work describes a comparison of the reactivity of glycolate, lactate and trifluorolactate with recombinant human glycolate oxidase, by means of rapid‐kinetics experiments in anaerobiosis. We show that trifluorolactate is a substrate for glycolate oxidase, whereas it is known as an inhibitor for NAD‐dependent enzymes, as is trifluoroethanol for NAD‐dependent alcohol dehydrogenases. Unexpectedly, it was observed that, once reduced, a flavin transfers an electron to an oxidized flavin, so that the end species is a flavin semiquinone, whatever the substrate. This phenomenon has not previously been described for a glycolate oxidase. Altogether, considering that another member of this flavoenzyme family (flavocytochrome b2, a lactate dehydrogenase) has also been shown to oxidize trifluorolactate (Lederer F et al. (2016) Biochim Biophys Acta 1864, 1215–21), this work provides another important piece of evidence which is hardly compatible with a hydride transfer mechanism for this flavoenzyme family.

A kinetic model was developed for the prediction of HTL product yields based on a chemical mechanism. The model was developed after experimental studies on food wastes and food processing wastes. The model parameters were determined by training the model on experimental data on HTL of food wastes. Two other models from the literature were also tested. The calculated yields were compared with a large range of experimental data from the literature. Yields of bio-oil and char can be predicted from the process conditions, temperature, holding time, dry matter content, and the biochemical composition of the resource. Differences in the experimental recovery procedure and polarity of the extraction solvent are taken into account. This study shows that a kinetic model based on compositions allows a more detailed representation of the hydrothermal reactions than models purely based on resources and products. The precision of any model remains, however, largely dependent on the quality of the input data.

This paper presents two recent simulation studies conducted at NSW Department of Planning and Environment on the impact on air quality across NSW and the Greater Metropolitan Region (GMR) urban areas due to a dust storm in February 2019 and Covid 19 lock down in NSW in 2021. These studies highlight the importance of using suitable air quality models to simulate the emissions and transport of air pollutants over a region to assess the impact of events on air quality and population exposure. The WRF-Chem model is used for the large-scale dust storm event and the WRF-CMAQ is used for assessing emission changes in the GMR due to the Covid-19 lockdown on the urban air quality. Both WRF-Chem and WRF-CMAQ are regional chemical transport models and require high-end Linux-based computing resources. The advantage and disadvantage of applying each of the two models to conduct a particular air quality study will be discussed. [ABSTRACT FROM AUTHOR]

The flavoenzyme glycolate oxidase oxidizes glycolic acid to glyoxylate and the latter, more slowly, to oxalate. It is a member of an FMN‐dependent enzyme family that oxidizes l‐2‐hydroxy acids to keto acids. There has been a controversy concerning the chemical mechanism of substrate oxidation by these enzymes. Do they proceed by hydride transfer, as observed for NAD‐dependent enzymes, or by initial formation of a carbanion that transfers the electrons to the flavin? The present work describes a comparison of the reactivity of glycolate, lactate and trifluorolactate with recombinant human glycolate oxidase, by means of rapid‐kinetics experiments in anaerobiosis. We show that trifluorolactate is a substrate for glycolate oxidase, whereas it is known as an inhibitor for NAD‐dependent enzymes, as is trifluoroethanol for NAD‐dependent alcohol dehydrogenases. Unexpectedly, it was observed that, once reduced, a flavin transfers an electron to an oxidized flavin, so that the end species is a flavin semiquinone, whatever the substrate. This phenomenon has not previously been described for a glycolate oxidase. Altogether, considering that another member of this flavoenzyme family (flavocytochrome b2, a lactate dehydrogenase) has also been shown to oxidize trifluorolactate (Lederer F et al. (2016) Biochim Biophys Acta 1864, 1215–21), this work provides another important piece of evidence which is hardly compatible with a hydride transfer mechanism for this flavoenzyme family. [ABSTRACT FROM AUTHOR]

In present work, two types of substrates for the surface enhanced Raman scattering (SERS) spectroscopy based on silver-coated porous silicon (por-Si) and HfOx/por-Si are engineered. The por-Si samples are formed by electrochemical etching the monocrystalline silicon and have a mean pore diameter of 850 nm and a porous layer thickness of 5 µm. Deposition of the hafnium oxide film on the por-Si surface is performed by atomic layer technique, while the SERS-active silver particles are grown by the chemical "silver mirror" method. The HfOx-free substrates demonstrate better SERS-activity but result in changes of the analyte molecule (Ellman's reagent) spectra, which is supposed to associate with their thermal degradation. Oppositely, the Ag/HfOx/por-Si samples provide sufficient and stable enough SERS-activity during at least 1-min SERS-measurements. We assume the observed stability of the analyte on the substrates containing HfOx can be caused by the faster heat dissipation from the laser spot due to more uniform and conformal silver coating than that on HfOx-free sample. The conformal deposition of silver is provided by passivation of the por-Si surface with auxiliary HfOx layer. An analytical enhancement factor for the Ag/HfOx/por-Si substrate equals to 2·103. Therefore, the SERS-active substrate containing HfOx provided athermal effect on analyte. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both AgNPs and Ag-decorated g-C 3 N 4 show excellent SERS activity. • Charge transfer calculations confirm that electrons drift towards the drug from the substrates. • Energy gap of the drug is reduced upon the incorporation of the substrates. • A low limit of detection of 10-12 M was successfully achieved. Herein, silver nanoparticles (AgNPs) and silver-loaded graphitic carbon nitride (Ag@g-C 3 N 4) nanocomposites have been synthesized and used as an effective surface-enhanced Raman scattering (SERS) substrates for the detection of low concentrations (10-14 M) of ciprofloxacin (CIP), a commonly bioactive medication used to treat bacterial illnesses. A combined approach of vibrational spectroscopy and density functional theory (DFT) has been developed to understand the possible modes of analyte (CIP) and SERS substrate (AgNPs and Ag@g-C 3 N 4) interactions. Furthermore, it has been noticed that the behavior of drug molecules in terms of SERS response and energetics of interaction changed significantly when interacted with the noble metal AgNPs decorated onto the g-C 3 N 4 framework in comparison to only AgNPs as substrate. The most prominent interaction scenario between AgNPs and CIP is likely to be through the –NH moiety of drug molecule with an interaction energy of −306 kcal/mol. Whereas, the CIP molecules adsorbed onto Ag@g-C 3 N 4 nanocomposite were more flexible with interaction energy of −107 kcal/mol, suggesting a greater association of analyte with the skeletal modes of substrate leading to Raman enhancements in the low wavenumber region i.e. below 600 cm−1. Hence, the Ag@g-C 3 N 4 nanocomposite-based SERS substrates investigated served two distinct spectral ranges, making them complementary of each other in terms of SERS detection of CIP. The characteristics of the computed frontier molecular orbitals indicated a pronounced amount of charge transfer between the drug and the substrate, highlighting the significance of the chemical mechanism of the overall process. These results represent a successful approach to have an extended spectral range that covers lower wavenumber shifts by applying simple and meaningful modifications to the normally utilized noble metal-based nanoparticles, which can lead to more effective and reliable detection of bioactive drugs. [ABSTRACT FROM AUTHOR]

A kinetic model was developed for the prediction of HTL product yields based on a chemical mechanism. The model was developed after experimental studies on food wastes and food processing wastes. The model parameters were determined by training the model on experimental data on HTL of food wastes. Two other models from the literature were also tested. The calculated yields were compared with a large range of experimental data from the literature. Yields of bio-oil and char can be predicted from the process conditions, temperature, holding time, dry matter content, and the biochemical composition of the resource. Differences in the experimental recovery procedure and polarity of the extraction solvent are taken into account. This study shows that a kinetic model based on compositions allows a more detailed representation of the hydrothermal reactions than models purely based on resources and products. The precision of any model remains, however, largely dependent on the quality of the input data. [ABSTRACT FROM AUTHOR]

In this study, modified products with a higher specific surface area and pore volume were prepared by light burning magnesite (MS) to increase its magnesium content and surface activity. MS heated at 650 °C (MS650) was applied in aerobic composting to assess its effect on nitrogen transformation during composting and the possible related chemical and microbial mechanisms. Adding MS650 reduced the NH 3 emissions (0.74-52.4%), N 2 O emissions (29.0-57.9%), and greenhouse gas emissions (41.8-60.3%), and its effect on reducing nitrogen emissions was negatively correlated with the amount added, where the optimum proportion of MS650 was 2.5%. Struvite precipitation and physical adsorption were the chemical mechanisms responsible for nitrogen retention. MS650 inhibited the growth of nitrifying, nitrate reducing, and denitrifying bacteria. The total organic carbon content, electrical conductivity, and N 2 O together explained most of the variation (52.7%) in nitrogen functional genes, followed by Proteobacteria (28.6%). These findings have important implications for reducing nitrogen and greenhouse gas emissions, and improving the quality of compost products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier Ltd. All rights reserved.)

We have structure, a wealth of kinetic data, thousands of chemical ligands and clinical information for the effects of a range of drugs on monoamine oxidase activity in vivo. We have comparative information from various species and mutations on kinetics and effects of inhibition. Nevertheless, there are what seem like simple questions still to be answered. This article presents a brief summary of existing experimental evidence the background and poses questions that remain intriguing for chemists and biochemists researching the chemical enzymology of and drug design for monoamine oxidases (FAD-containing EC 4.1.3.4).

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The antifungal mechanism of plant essential oil has always been a concern in the agriculture and forestry science field. In this investigation, besides the evaluation of inhibitory activities of twenty-three essential oils against Candida albicans in vitro, identification and quantification of the chemical composition of Litsea cubeba essential oil by gas chromatography-mass spectrometry were investigated. Further development, we assessed the mechanism of L. cubeba essential oil against C. albicans by molecular docking. Litsea cubeba essential oil displayed the strongest inhibitory activity among these oils and the diameter of the circle against C. albicans was more than 50 mm. Maximum three components were identified with transcitral (33.6%), cis-citral (30.3%), d-limonene (8.2%). Secretory aspartate protease (SAP5) and β-1,3-glucan synthase (β-1,3-GS) are two key enzyme proteins that inhibit the growth of C. albicans. Molecular docking studies reveal chemical binding forces of cis-citral, trans-citral and d-limonene to SAP5 are -21.76 kJ/mol, -22.18 kJ/mol and -24.27 kJ/mol, to β-1,3-GS are -23.01 kJ/mol, -25.52 kJ/mol and -23.85 kJ/mol, respectively. The most preferable binding mechanism was observed against SAP5 and β-1,3-GS due to hydrophobic interaction, as well as hydrogen bonding between citral molecules. The research results suggest the mechanism of chemical components in L. cubeba essential oil inhibits the growth of C. albicans, which provides a reference to the development and utilization of essential oil. [ABSTRACT FROM AUTHOR]

Moderate or Intense Low–oxygen Diluted (MILD) combustion is a promising technology with interesting ‎properties such as high efficiency and zero-emission. The biogas-syngas mixture is also considered a ‎promising new renewable biofuel with low emissions. This work aims to examine the effects of several ‎parameters on the biogas-syngas flame structure and emissions under MILD conditions in the Jet in Hot ‎Co flow (JHC) burner. The turbulence is modeled by the modified standard k-ε model; whereas ‎combustion-turbulence interaction is handled by the Eddy Dissipation Concept (EDC) in conjunction with ‎three detailed reaction mechanisms, namely: GRI-Mech 3.0, GRI-Mech 2.11, and DRM 2.11. Effects of ‎biogas-syngas composition, temperature, and oxygen concentration in the hot co-flow and Reynolds ‎number of the fuel jet have been elucidated. Results show that flame structure is more sensitive to the ‎increase of hydrogen in syngas than that of methane in biogas. An increase of oxygen concentration or ‎temperature in the co-flow stream leads to more NO formation whereas Reynolds number augmentation ‎reduced them. Furthermore, NO species production is globally governed by the NNH route‎‎.

Volatile organic compounds (VOCs) oxidation processes play a very important role in atmospheric chemistry, and the chemical reactions are expressed in various manners in chemical mechanisms. To gain an improved understanding of VOCs evolution during oxidation processes and evaluate the discrepancies of VOCs oxidation schemes among different mechanisms, we used the total VOC reactivity as a diagnostic and evaluated tool to explore the differences for six widely used chemical mechanisms. We compared the total VOC reactivity evolution under high-NO x conditions for several sets of precursors, including n-pentane, toluene, ethene, isoprene and a mixture of 57 Photochemical Assessment Monitoring Stations (PAMS) species in a 0-D photochemical box model. Inter-comparison of total VOC reactivity of individual precursor simulations showed discrepancies to different extent of the oxidation schemes among the studied mechanisms, which are mainly attributed to the different lumping approaches for organic species. The PAMS simulation showed smaller discrepancy than individual precursor cases in terms of total VOC reactivity. SAPRC07 and RACM2 performances are found to better match the MCM for simulation of total VOC reactivity. Evidences suggest that the performance in simulating secondary organic products, OH concentrations and NO x concentrations are related to the OH reactivity discrepancies among various chemical mechanisms. Information in this study can be used in selection of chemical mechanisms to better model OH reactivity in different environments. The results in this study also provide directions to further improve the ability in modelling total VOC reactivity with the chemical mechanisms. [Display omitted] [ABSTRACT FROM AUTHOR]

For source apportionment by tracer method of secondary organic aerosol (SOA), the ratios of aerosol tracer to total SOA mass (fSOA) were determined during the oxidation of toluene, naphthalene, α-pinene, and isoprene by a series of laboratory experiments. Seven anthropogenic SOA tracers maintaining an aromatic ring structure, including 4-nitrophthalic acid and 3,5-dinitrosalicylic, were newly investigated as a chamber study together with 21 traditional aerosol tracers of anthropogenic and biogenic SOA. Experiments of the OH-initiated oxidation of anthropogenic VOCs were conducted as a function of the initial VOC/NOx ratio. No significant dependence on the VOC/NOx ratio was observed for the fSOA of 2,3-dihydroxy-4-oxopentanoic acid from toluene and phthalic acid from naphthalene, whereas the fSOA of nitroaromatic compounds such as 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, and 4-nitrophthalic acid increased with decreasing VOC/NOx ratio. Among seven newly evaluated anthropogenic SOA tracers, we concluded that 3,5-dinitronsalicylic can be used as a toluene SOA tracer, whereas 4-nitrophthalic acid can be used as a naphthalene SOA tracer. Results of kinetic calculations suggest that naphthalene is a major source of 5-nitrosalicylic acid under urban and rural conditions of previous observation studies. The ozonolysis and NO3-initiated oxidation of biogenic VOCs were investigated in addition to OH-initiated oxidation of biogenic VOCs. As for biogenic SOA tracers such as pinic acid and 2-methyltetrols, the fSOA value measured for the NO3-intiated reaction was lower than that of the OH-initiated oxidation and the fSOA value measured for the ozonolysis was not necessarily close to that of the OH-initiated oxidation. These results suggest that daytime and nighttime biogenic SOA formation events are interpreted by using different sets of the fSOA values.

Few atom thick, twisted bilayer graphene (tBLG) possesses a rotation angle (θ) dependent van Hove singularity (vHs). Fine-tuning vHs serves a potential method to enhance charge transfer (CT) in surface enhanced Raman spectroscopy. This study shows that tBLG having a specific θ promotes as high as a 1.7 times enhancement of the Raman signals of copper phthalocyanine (CuPc) as compared to that caused by single layer graphene (SLG). The results of a combination of reflection imaging spectroscopy and widefield Raman provide spatial and spectral information about both tBLG with θ ranging from 10.9 to 13.7° and the corresponding vHs. Comparison of Raman spectra of CuPc in presence and absence of tBLG demonstrates that a significant enhancement of certain CuPc vibrational modes occurs when the underlying tBLG possesses a θ = 12.2°, showing as high as 6.8 and 1.7 times enhancements of certain vibrational mode as compared to those of CuPc on bare and SLG substrates, respectively. Theoretical calculations indicate that a match between the energies of vHs of tBLG with those of frontier orbitals of CuPc facilitates CT from the distant SLG to CuPc. [Display omitted] [ABSTRACT FROM AUTHOR]

Atomic layer deposition (ALD) has become an indispensable thin-film technology in the contemporary microelectronics industry. The unique self-limited layer-by-layer growth feature of ALD has outstood this technology to deposit highly uniform conformal pinhole-free thin films with angstrom-level thickness control, particularly on 3D topologies. Over the years, the ALD technology has enabled not only the successful downscaling of the microelectronic devices but also numerous novel 3D device structures. As ALD is essentially a variant of chemical vapor deposition, a comprehensive understanding of the involved chemistry is of crucial importance to further develop and utilize this technology. To this end, we, in this review, focus on the surface chemistry and precursor chemistry aspects of ALD. We first review the surface chemistry of the gas–solid ALD reactions and elaborately discuss the associated mechanisms for the film growth; then, we review the ALD precursor chemistry by comparatively discussing the precursors that have been commonly used in the ALD processes; and finally, we selectively present a few newly-emerged applications of ALD in microelectronics, followed by our perspective on the future of the ALD technology.

The prospects of 2-methylfuran (2MF) as a biofuel and gasoline blend stock are quite high. Therefore, a skeletal chemical kinetic mechanism – containing 238 species and 1156 reactions – for the simulation of premixed flames involving isooctane (representing gasoline)/2MF blends is proposed in the present work. The proposed model has been validated against a wide range of experimental data at various pressures, temperatures and compositions. It is demonstrated in the present work that the proposed mechanism can predict the concentrations of gaseous soot precursors as well. Moreover, the compatibility of the NOx sub-mechanism in the present model has been assured through validations against a wide range of recent experimental data. The results obtained in this work suggest that there are little chances of co-oxidation reactions among the species generated from the initial decomposition of both isooctane and 2MF. Furthermore, there is around 26% variation in the peak laminar burning velocity when the mole fraction of 2MF is increased from 10% to 90% in isooctane/2MF blend. [ABSTRACT FROM AUTHOR]

Moderate or Intense Low–oxygen Diluted (MILD) combustion is a promising technology with interesting properties such as high efficiency and zero-emission. The biogas-syngas mixture is also considered a promising new renewable biofuel with low emissions. This work aims to examine the effects of several parameters on the biogas-syngas flame structure and emissions under MILD conditions in the Jet in Hot Co flow (JHC) burner. The turbulence is modeled by the modified standard k-ε model; whereas combustion-turbulence interaction is handled by the Eddy Dissipation Concept (EDC) in conjunction with three detailed reaction mechanisms, namely: GRI-Mech 3.0, GRI-Mech 2.11, and DRM 2.11. Effects of biogas-syngas composition, temperature, and oxygen concentration in the hot co-flow and Reynolds number of the fuel jet have been elucidated. Results show that flame structure is more sensitive to the increase of hydrogen in syngas than that of methane in biogas. An increase of oxygen concentration or temperature in the co-flow stream leads to more NO formation whereas Reynolds number augmentation reduced them. Furthermore, NO species production is globally governed by the NNH route. [ABSTRACT FROM AUTHOR]

Lightweight embankment is an effective method for soft foundation treatment, while decreasing its cement usage can protect environment, save resource and reduce cost. This study aims to develop a lightweight cement composite (LC) containing fly ash and sand to provide guidance for filling the sustainable embankment. The chemical mechanism, micro-morphology, mechanical strength and workability of lightweight cement composites were evaluated through macro-micro tests, as well as life cycle assessment was performed to analyze the sustainability, and determine the optimal mixing ratio. The results showed that the moderate amount of fly ash was beneficial to enhance the mechanical strength of LC, while adding sand further improved its ductility, toughness, workability and sustainability. When the replacement rate of fly ash and sand were 10 % and 20 %, the energy absorption and fluidity of LC increased by 57 % and 7 %, and its ductility index, carbon emission and construction cost decreased by 34 %, 46 % and 35 %, respectively. Fly ash reacted with calcium hydroxide produced by cement hydration to generate more calcium silicate gels, which reduced the large pore of LC and improved its internal structure, while sand played a certain skeleton role. • Developing an eco-friendly and practical lightweight cement composite. • The applicability and chemical mechanism of lightweight cement composites are assessed. • Utilizing fly ash and sand in cement composite shows better sustainability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphene monolayers are transferred successfully onto glass substrates from Cu substrate using the polymer-assisted exfoliation method. • Raman spectra of crystal violet (CV) and IR-780 Iodide molecules dispersed on the monolayer graphene film (MGF) are recorded. • In the CV-MGF system, the irreversible charge transfer is observed irrespective of the laser spot position. • Interestingly, for the first time, the reversible charge transfer observed in the IR-780 iodide-MGF system strongly depends upon the laser spot position. Herein, we report the Raman spectroscopy of crystal violet (CV) and IR-780 Iodide molecules dispersed on the monolayer graphene film (MGF). In the CV-MGF system, the enhancement in the Raman scattering of CV molecules is observed irrespective of the location probed during the spectral measurements. This enhancement is due to the charge transfer from the MGF to CV molecules. However, in the case of the IR-780 Iodide – MGF system, the enhancement of Raman scattering of dye molecules or MGF is observed strongly depending upon the probed location. These observations indicate that the charge transfer is irreversible and reversible in the CV-MGF and IR-780 Iodide–MGF systems, respectively. Importantly, for the first time, this experimental study revealed that enhancing the Raman scattering of MGF is possible through the "chemical mechanism" with suitable dye molecules apart from the "electromagnetic mechanism" with plasmonic hot spots of the metal nanoparticles and photonic nanojets of single dielectric microparticles. [ABSTRACT FROM AUTHOR]

Summary: The pyrolysis gas consisting of 29.4% CH4, 21.3% C2H4, 30.8% C2H6, and 18.5% C3H6 in mole fraction is presented, as the surrogate of the actual gaseous pyrolysis products. At the conditions of TC = 877.7‐963 K, PC = 3.22‐4.37 MPa, φ = 0.5 and 1.0, the ignition delays of pyrolysis gas/air (diluted with 52% Ar) have been measured. With TC or PC increasing, the ignition delay time decreases. The auto‐ignition of φ = 1.0 is faster than that of φ = 0.5. Furthermore, two widely used small hydrocarbons chemical mechanisms are validated with the measured results. The USC‐II mechanism can well predict experimental results at high‐T regimes, but fails at low‐T regimes. By sensitivity analysis of temperature, the two elementary reactions C2H6 + OH = C2H5 + H2O (negative sensitivity coefficient) and C3H6 + OH = aC3H5 + H2O (positive sensitivity coefficient) have been identified, which have higher reactivity at low‐T and lower reactivity at high‐T. Considering the extreme uncertainty of rate constants of C3H6 + OH = aC3H5 + H2O, the kinetic parameters have been modified for improving the predictions. The validated results indicate that the optimized mechanism improves predictions of the auto‐ignition behavior at low temperature regimes. [ABSTRACT FROM AUTHOR]

We have structure, a wealth of kinetic data, thousands of chemical ligands and clinical information for the effects of a range of drugs on monoamine oxidase activity in vivo. We have comparative information from various species and mutations on kinetics and effects of inhibition. Nevertheless, there are what seem like simple questions still to be answered. This article presents a brief summary of existing experimental evidence the background and poses questions that remain intriguing for chemists and biochemists researching the chemical enzymology of and drug design for monoamine oxidases (FAD-containing EC 4.1.3.4). [ABSTRACT FROM AUTHOR]

In relation to the grave consequences arising after accidents at nuclear power plants (NPPs) caused or accompanied by explosions and ignition of hydrogen–air mixtures, the need for a more thorough approach to study the accompanying physicochemical processes has emerged. This paper presents a brief analysis of these situations in the light of prevention of hydrogen explosions at NPPs and the use of catalysts based on platinum and palladium for the utilization of hydrogen. The interaction of a hydrogen–air flame with the surface of a bulk catalyst is experimentally investigated, and the efficiencies of the selected catalysts are compared with respect to the heterogeneous reaction of hydrogen oxidation. The dependence of the experimental results on the design and location of the functional zones of the reactor is analyzed. [ABSTRACT FROM AUTHOR]

Severe haze pollution occurs frequently in the winter over the Beijing-Tianjin-Hebei (BTH) region (China), exerting profound impacts on air quality, visibility, and human health. The Chinese Government has taken strict mitigation actions since 2013 and has achieved a significant reduction in the annual mean PM2.5 concentration over this region. However, the level of secondary aerosols during heavy haze episodes showed little decrease during this period. During heavy haze episodes, the concentrations of secondary aerosol components, including sulfate, nitrate and secondary organics, in aerosol particles increase sharply, acting as the main contributors to aerosol pollution. To achieve effective control of particle pollution in the BTH region, the precise and complete secondary aerosol formation mechanisms have been investigated, and advances have been made about the mechanisms of gas phase reaction, nucleation and heterogeneous reactions in forming secondary aerosols. This paper reviews the research progress in aerosol chemistry during haze pollution episodes in the BTH region, lays out the challenges in haze formation studies, and provides implications and directions for future research. [ABSTRACT FROM AUTHOR]

Surface enhanced Raman scattering (SERS) is a fingerprint spectral technique whose performance is highly dependent on the physicochemical properties of the substrate materials. In addition to the traditional plasmonic metal substrates that feature prominent electromagnetic enhancements, boosted SERS activities have been reported recently for various categories of non-metal materials, including graphene, MXenes, transition-metal chalcogens/oxides, and conjugated organic molecules. Although the structural compositions of these semiconducting substrates vary, chemical enhancements induced by interfacial charge transfer are often the major contributors to the overall SERS behavior, which is distinct from that of the traditional SERS based on plasmonic metals. Regarding charge-transfer-induced SERS enhancements, this short review introduces the basic concepts underlying the SERS enhancements, the most recent semiconducting substrates that use novel manipulation strategies, and the extended applications of these versatile substrates.

Abstract The Community Earth System Model version 2 (CESM2) includes a detailed representation of chemistry throughout the atmosphere in the Community Atmosphere Model with chemistry and Whole Atmosphere Community Climate Model configurations. These model configurations use the Model for Ozone and Related chemical Tracers (MOZART) family of chemical mechanisms, covering the troposphere, stratosphere, mesosphere, and lower thermosphere. The new MOZART tropospheric chemistry scheme (T1) has a number of updates over the previous version (MOZART‐4) in CESM, including improvements to the oxidation of isoprene and terpenes, organic nitrate speciation, and aromatic speciation and oxidation and thus improved representation of ozone and secondary organic aerosol precursors. An evaluation of the present‐day simulations of CESM2 being provided for Climate Model Intercomparison Project round 6 (CMIP6) is presented. These simulations, using the anthropogenic and biomass burning emissions from the inventories specified for CMIP6, as well as online calculation of emissions of biogenic compounds, lightning NO, dust, and sea salt, indicate an underestimate of anthropogenic emissions of a variety of compounds, including carbon monoxide and hydrocarbons. The simulation of surface ozone in the southeast United States is improved over previous model versions, largely due to the improved representation of reactive nitrogen and organic nitrate compounds resulting in a lower ozone production rate than in CESM1 but still overestimates observations in summer. The simulation of tropospheric ozone agrees well with ozonesonde observations in many parts of the globe. The comparison of NOx and PAN to aircraft observations indicates the model simulates the nitrogen budget well.

While fuel combustion in oxygen-enriched environments provides a number of significant advantages, such as reduced nitrogen oxide emissions and high carbon dioxide purity for carbon sequestration, it is characterized by different physico-chemical oxidation behavior than combustion in air. Compared to nitrogen, carbon dioxide has different specific heat and effective Lewis number, and is chemically more active. Therefore, chemical mechanisms developed for the oxidation of fuel/air mixtures can fail to predict targets of interest for oxy-combustion accurately. In this study, a chemical mechanism of methane, which has been previously validated with data from experiments using air, is evaluated in terms of its prediction accuracy at oxy-conditions by comparing against available literature data. The validation takes various combustion properties into account, including ignition delay times, laminar burning velocities, and extinction strain rates, and covers a wide range of experimental conditions with respect to temperature, pressure, equivalence ratio, and carbon dioxide concentration. As additional targets, extinction strain rates of non-premixed oxy-methane flames are determined in a counterflow burner at conditions, where literature data have not yet been reported. The extensive validation demonstrates that the mechanism is able to describe oxy-methane combustion with reasonable prediction accuracy. For further insights into the underlying kinetics of diffusion flames of methane in oxy-atmosphere compared to its oxidation in air, reaction path and sensitivity analyses are performed using the validated mechanism. Notable differences between both combustion regimes are observed in the branching ratios of H-abstraction reactions by OH and H radicals and in the consumption channels of singlet methylene, which is a key species in the formation of polycyclic aromatic hydrocarbons. [ABSTRACT FROM AUTHOR]

Graph‐theoretical methods have revolutionized the exploration of complex systems across scientific disciplines. Here, we demonstrate their applicability to the investigation and comparison of three widely used atmospheric chemical mechanisms of varying complexity: the Master Chemical Mechanism v3.3, GEOS‐Chem v12.6, and the Super‐Fast chemical mechanism. We investigate these mechanisms using a class of graphical models known as species‐reaction graphs and find similarities between these chemical reaction systems and other systems arising in nature. Several graph theoretical properties are consistent across mechanisms, including strong dynamical system disequilibrium and clustering of chemically related species. This formalism also reveals key differences between the mechanisms, some of which have characteristics inconsistent with domain knowledge; e.g., isoprene and peroxy radical chemistry exhibit substantially different graph properties in each mechanism. Graph‐theoretical methods provide a promising set of tools for investigating atmospheric chemical mechanisms, complementing existing computational approaches, and potentially opening new avenues for scientific discovery. Plain Language Summary: A type of math known as "graph theory" provides a set of tools for scientific discovery in a variety of contexts. These include the study of social networks, the power grid, and the human brain. In this paper, we apply these tools to the study of the chemical reactions that occur in the atmosphere. We investigate and intercompare several different descriptions of these reactions, and find that these new graph theory‐based techniques provide information consistent with existing scientific techniques, and potentially allow for new avenues for scientific discovery. Key Points: We investigate three atmospheric chemical mechanisms of varying complexity and process representation using graph‐theoretical techniquesResults are consistent with existing computational approaches, demonstrating key similarities and differences between the mechanismsThese techniques provide chemical state independent, structural insights into existing mechanisms, and methods for new mechanism development [ABSTRACT FROM AUTHOR]

Atmospheric chemistry models—components in models that simulate air pollution and climate change—are computationally expensive. Previous studies have shown that machine‐learned atmospheric chemical solvers can be orders of magnitude faster than traditional integration methods but tend to suffer from numerical instability. Here, we present a modeling framework that reduces error accumulation compared to previous work while maintaining computational efficiency. Our approach is novel in that it (1) uses a recurrent training regime that results in extended (>1 week) simulations without exponential error accumulation and (2) can reversibly compress the number of modeled chemical species by >80% without further decreasing accuracy. We observe an ~260× speedup (~1,900× with specialized hardware) compared to the traditional solver. We use random initial conditions in training to promote general applicability across a wide range of atmospheric conditions. For ozone (concentrations ranging from 0–70 ppb), our model predictions over a 24‐hr simulation period match those of the reference solver with median error of 2.7 and <19 ppb error across 99% of simulations initialized with random noise. Error can be significantly higher in the remaining 1% of simulations, which include extreme concentration fluctuations simulated by the reference model. Results are similar for total particulate matter (median error of 16 and <32 μg/m3 across 99% of simulations with concentrations ranging from 0–150 μg/m3). Finally, we discuss practical implications of our modeling framework and next steps for improvements. The machine learning models described here are not yet replacements for traditional chemistry solvers but represent a step toward that goal. Key Points: We create a machine‐learned surrogate model of an atmospheric chemical solver which operates orders of magnitude faster than the originalWe use a recurrent training regime to yield models that improve numerical stability relative to previous effortsOur models can reversibly compress the number of modeled chemical species by greater than 80% without decreasing accuracy [ABSTRACT FROM AUTHOR]

A new state-of-the-art indoor smog chamber facility (CAPS-ZJU) has been constructed and characterized at Zhejiang University, which is designed for chemical mechanism evaluation under well-controlled conditions. A series of characterization experiments were performed to validate the well-established experimental protocols, including temperature variation pattern, light spectrum and equivalent intensity (J NO2), injection and mixing performance, as well as gases and particle wall loss. In addition, based on some characterization experiments, the auxiliary wall mechanism has been setup and examined. Fifty chamber experiments were performed across a broad range of experimental scenarios, and we demonstrated the ability to utilize these chamber data for evaluating SAPRC chemical mechanism. It was found that the SAPRC-11 can well predict the O 3 formation and NO oxidation for almost all propene runs, with 6 hr Δ(O 3 – NO) model error of –3% ± 7%, while the final O 3 was underestimated by ~20% for isoprene experiments. As for toluene and p -xylene experiments, it was confirmed that SAPRC-11 has significant improvement on aromatic chemistry than earlier version of SAPRC-07, although the aromatic decay rate was still underestimated to some extent. The model sensitivity test has been carried out, and the most sensitive parameters identified are the initial concentrations of reactants and the light intensity as well as HONO offgasing rate and O 3 wall loss rate. All of which demonstrated that CAPS-ZJU smog chamber could derive high quality experimental data, and could provide insights on chamber studies and chemical mechanism development. Image, graphical abstract [ABSTRACT FROM AUTHOR]

There is a growing need to design fuel flexible combustors. This require understanding of the combustion and emission characteristics of the combustors under varying fuel compositions. In the present study, the combustion characteristics and emission of methane and syngas flames were investigated numerically in a swirl stabilized combustor. The numerical model was developed using ANSYS-fluent software and validated using experimental values of temperature, CO2 and NOx emissions. A two-step chemical mechanism was used to model methane-air combustion. Results of the numerical validation showed similar trend between the experimental and predicted temperature along the combustor axis with about 5 % over prediction of the temperature. Syngasair combustion was thereafter modeled using a 21 step chemical mechanism. Syngas compositions studied were: syngas A (67% CO: 33% H2), syngas B (50% CO: 50% H2) and syngas C (33% CO: 67% H2). Results showed that for pure methane, a V-shaped flame was observed with the flame attached to the fuel nozzle, while a lifted flame was observed for case of syngas A composition. CO gas with higher ignition temperature and flammability as compared to H2 gas is the dominant gas in syngas A fuel composition. Jet flames were observed for syngas B and syngas C. Carbon monoxide is a slow burning gas. Therefore syngas with low CO content has a low tendency of emission of CO from the combustor. This suggests that syngas with high CO content such syngas A may require more residence time to completely combust the CO gas. The NOx emission was observed to have the same trend as that of the combustor maximum temperature. Syngas C flame had the highest NOx emission, while, syngas A flame had no NOx emission. This is due to low combustor temperature observed in the case of syngas A flame. [ABSTRACT FROM AUTHOR]

In this paper, we study the effect of a heterogeneous autocatalytic reaction on the quartz reactor surface occurring after ignition in an H2/O2 medium near the third limit on the initiation of an explosion of a hydrogen–oxygen mixture in a cold volume of lines adjacent to the reactor. Under certain conditions, a second flash occurs in most experiments in a cold volume. The probable chemical mechanism of the processes occurring is proposed. [ABSTRACT FROM AUTHOR]

The Community Earth System Model version 2 (CESM2) includes a detailed representation of chemistry throughout the atmosphere in the Community Atmosphere Model with chemistry and Whole Atmosphere Community Climate Model configurations. These model configurations use the Model for Ozone and Related chemical Tracers (MOZART) family of chemical mechanisms, covering the troposphere, stratosphere, mesosphere, and lower thermosphere. The new MOZART tropospheric chemistry scheme (T1) has a number of updates over the previous version (MOZART‐4) in CESM, including improvements to the oxidation of isoprene and terpenes, organic nitrate speciation, and aromatic speciation and oxidation and thus improved representation of ozone and secondary organic aerosol precursors. An evaluation of the present‐day simulations of CESM2 being provided for Climate Model Intercomparison Project round 6 (CMIP6) is presented. These simulations, using the anthropogenic and biomass burning emissions from the inventories specified for CMIP6, as well as online calculation of emissions of biogenic compounds, lightning NO, dust, and sea salt, indicate an underestimate of anthropogenic emissions of a variety of compounds, including carbon monoxide and hydrocarbons. The simulation of surface ozone in the southeast United States is improved over previous model versions, largely due to the improved representation of reactive nitrogen and organic nitrate compounds resulting in a lower ozone production rate than in CESM1 but still overestimates observations in summer. The simulation of tropospheric ozone agrees well with ozonesonde observations in many parts of the globe. The comparison of NOx and PAN to aircraft observations indicates the model simulates the nitrogen budget well. Plain Language Summary: The set of chemical reactions for tropospheric chemistry used in the Community Earth System Model version 2 (CESM2) has been updated significantly over CESM1 in the Community Atmosphere Model with chemistry (CAM‐chem) and Whole Atmosphere Community Climate Model (WACCM) configurations. The emissions used for the CESM2 simulations are documented here, with anthropogenic and biomass burning emissions based on the specified inventories for Climate Model Intercomparison Project 6 (CMIP6), and emissions of biogenic compounds, lightning NO, dust, and sea salt are calculated online and dependent on the simulated meteorology. Evaluation of the CAM‐chem and WACCM configurations of CESM2 with observations indicate an underestimate of anthropogenic emissions of a variety of compounds, including carbon monoxide and hydrocarbons. The updated chemistry leads to an improvement in the simulation of tropospheric ozone. Key Points: This paper fully documents the significant updates to the chemistry mechanisms in version 2 of the Community Earth System ModelThe new tropospheric chemistry scheme improves representation of isoprene oxidation as well as other ozone precursors over earlier versionsThe simulation of tropospheric ozone is improved in comparison to observations [ABSTRACT FROM AUTHOR]

To distinguish the effects of chemical mechanisms and meteorological factors on air pollution in the megacity of Beijing, the sensitive numerical experiments with the third-generation air quality modeling system (WRF-SMOKE-CMAQ) are designed for a one-year simulation in 2018. The results indicate that: 1) the modeling system plays well in performance in the megacity of Beijing in 2018. The correlation coefficient of the simulated PM 2.5 concentration and the observation value reaches 0.74, while the normal mean bias is −14%–32% in the National Standard Air Quality observation stations in Beijing. 2) The impact of chemical mechanisms on pollutants such as ANO 3 is significant, reaching 1075%. However, there is almost no impact on AEC, or ASO 4 from the chemical mechanisms. The impact of chemical mechanisms on NO and O 3 concentration is between the aforementioned two, with a relatively small degree of impact. The influence of chemical mechanisms on PM 2.5 concentration is 35%, while the meteorological factors are 65% under the experiments. 3) For the photochemical species, the peak frequencies of NO 2 concentration in the two experiments are 27.1 ppbV and 5.9 ppbV, respectively, and the peak frequency of NO 2 observed concentration is 19.1 ppbV, near to the simulation in the baseline group, which illustrates that the chemical mechanism includes a large amount of NO 2 generation. The numerical model is a good tool to quantify the effect of chemical mechanisms and meteorological factors. In addition, the concentration of NO 2 in Beijing is decreasing from urban to exurb areas in terms of spatial distribution, and the spatial variation of PM 2.5 is also the same. • The influence of chemical mechanisms on PM 2.5 concentration is 35%, while the influence of meteorological factors is 65%. • The chemical mechanisms have varying impact on the PM components, a significant on ANO 3 , while a little impact on ASO 4. • The difference in the peak frequency of the normal distribution on NO 2 between the two experiments reached 8 ppbV. [ABSTRACT FROM AUTHOR]

We investigated the kinetics, mechanism and secondary organic aerosols formation of the ozonolysis of trans-2-pentenal (T2P) using four different reactors with Fourier Transform InfraRed (FTIR) spectroscopy and Gas Chromatography (GC) techniques at T = 298 ± 2 K and 760 Torr in dry conditions. The rate coefficients and branching ratios were also evaluated using the canonical variational transition (CVT) state theory coupled with small curvature tunneling (CVT/SCT) in the range 278–350 K. The experimental rate coefficient at 298 K was (1.46 ± 0.17) × 10−18 cm3 molecule−1 s−1, in good agreement with the theoretical rate. The two primary carbonyls formation yields, glyoxal and propanal, were 57 ± 10% and 42 ± 12%, respectively, with OH scavenger compared to 38 ± 8% for glyoxal and 26 ± 5% for propanal without OH scavenger. Acetaldehyde and 2-hydroxypropanal were also identified and quantified with yields of 9 ± 3% and 5 ± 2%, respectively, in the presence of OH scavenger. For the OH production, an upper limit of 24% was estimated using mesitylene as OH tracer. Combining experimental and theoretical findings enabled the establishment of a chemical mechanism. Finally, the SOA formation was observed with mass yields of about 1.5%. This work provides additional information on the effect of the aldehyde functional group on the fragmentation of the primary ozonide.

To better understand precursors of dicarboxylic acids in ambient secondary organic aerosol (SOA), we studied C4–C9 dicarboxylic acids present in SOA formed from the oxidation of toluene, naphthalene, α-pinene, and isoprene. C4–C9 dicarboxylic acids present in SOA were analyzed by offline derivatization gas chromatography–mass spectrometry. We revealed that C4 dicarboxylic acids including succinic acid, maleic acid, fumaric acid, malic acid, DL-tartaric acid, and meso-tartaric acid are produced by the photooxidation of toluene. Since meso-tartaric acid barely occurs in nature, it is a potential aerosol tracer of photochemical reaction products. In SOA particles from toluene, we also detected a compound and its isomer with similar mass spectra to methyltartaric acid standard; the compound and the isomer are tentatively identified as 2,3-dihydroxypentanedioic acid isomers. The ratio of detected C4–C5 dicarboxylic acids to total toluene SOA mass had no significant dependence on the initial VOC/NOx condition. Trace levels of maleic acid and fumaric acid were detected during the photooxidation of naphthalene. Malic acid was produced from the oxidation of α-pinene and isoprene. A trace amount of succinic acid was detected in the SOA produced from the oxidation of isoprene.

Surface-enhanced Raman spectroscopy (SERS) is an ultrasensitive surface analysis technique that is widely used in chemical sensing, bioanalysis, and environmental monitoring. The design of the SERS substrates is crucial for obtaining high-quality SERS signals. Recently, 2D transition metal dichalcogenides (2D TMDs) have emerged as high-performance SERS substrates due to their superior stability, ease of fabrication, biocompatibility, controllable doping, and tunable bandgaps and excitons. In this review, a systematic overview of the latest advancements in 2D TMDs SERS substrates is provided. This review comprehensively summarizes the candidate 2D TMDs SERS materials, elucidates their working principles for SERS, explores the strategies to optimize their SERS performance, and highlights their practical applications. Particularly delved into are the material engineering strategies, including defect engineering, alloy engineering, thickness engineering, and heterojunction engineering. Additionally, the challenges and future prospects associated with the development of 2D TMDs SERS substrates are discussed, outlining potential directions that may lead to significant breakthroughs in practical applications., (© 2024 Wiley‐VCH GmbH.)