Polar Components Research Articles

Effects of cosolvents on CO2 displacement of shale oil and carbon storage

Molecular dynamics method was used to establish composite wall/inorganic nanopores of three pore sizes, three shale oil systems, five CO2-cosolvent systems, and pure CO2 system. The process of CO2-cosolvent displacement of crude oil in shale nanopores and carbon storage was simulated and the influencing factors of displacement and storage were analyzed. It is shown that the attraction of the quartz wall to shale oil increases with the degree of hydroxylation. The higher the degree of quartz hydroxylation, the more difficult it is to extract the polar components of shale oil. Nanopore size also has a great impact on shale oil displacement efficiency. The larger the pore size, the higher the shale oil displacement efficiency. The closer the cosolvent molecules are to the polarity of the shale oil, the higher the mutual solubility of CO2 and shale oil. The more the non-polar components of shale oil, the lower the mutual solubility of CO2 and shale oil with highly polar cosolvent. Ethyl acetate is more effective in stripping relatively high polar shale oil, while dimethyl ether is more effective in stripping relatively low polar shale oil. Kerogen is highly adsorptive, especially to CO2. The CO2 inside the kerogen is not easy to diffuse and leak, thus allowing for a stable carbon storage. The highest CO2 storage rate is observed when dimethyl ether is used as a cosolvent, and the best storage stability is observed when ethyl acetate is used as a cosolvent.

Thermomechanic behavior of epitaxial GeTe ferroelectric films

A key development toward new electronic devices integrating memory and processing capabilities could be based on the electric control of the spin texture of charge carriers in semiconductors. In that respect, GeTe has been recently recognized as a promising ferroelectric Rashba semiconductor, with giant spin splitting of the band structure, due to the inversion symmetry breaking arising from ferroelectric polarization. Here, we address the temperature dependence of the ferroelectric structure of GeTe thin films grown on Si(111). We demonstrate the hysteretic behavior of the ferroelectric domain density upon heating/cooling cycles by low energy electron microscopy. This behavior is associated with an abnormal evolution of the GeTe lattice parameter as shown by x-ray diffraction. We explain these thermomechanical phenomena by a large difference of thermal expansion coefficients between the film and the substrate and to the pinning of the GeTe/Si interface. The accumulated elastic energy by the GeTe thin film during sample cooling is released by the formation of a-nanodomains with in-plane ferroelectric polarization components.

High-efficiency spin-selected multi-foci terahertz metalens

Metasurfaces have demonstrated extraordinary abilities in modulating light waves and, therefore, have been used in many applications. In this paper, we demonstrate multifocal metalens with high focusing efficiency controlled by circular polarization multiplexing. Under normal incidence of linearly polarized light, the metalens can generate transversely distributed four focal points, two of them support left-circularly polarized (LCP) conversion and the rest correspond to right-circularly polarized (RCP) conversion. The total focusing efficiency of the metalens as high as 60.38% is obtained. Excellent extinction is obtained for the focused beam, which achieves a focused polarization component energy of more than 96% in the focused region. In addition, we designed an oblique incidence metalens using the same structure and method. For 30°obliquely incident terahertz waves, high total focusing efficiency of 51.12% in the designed metalens is achieved. Focused polarization component energy exceeds 92% in the focused region. This provides potential new applications for polarization imaging and polarization detection.

Visual study of methane hydrate kinetics in a microfluidic chip: Effect of the resins extracted from the crude oil

Hydrate plugging in oil and gas transport pipelines is a crucial challenge to the safety of flow and maintenance of pipelines. Specifically, the resins, the strongest polar component in crude oil would significantly affect hydrate kinetics but the mechanism of the interaction remains unclear. Here, a microfluidic chip was used to monitor the hydrate formation under gas flow in-situ, with and without resins extracted from the crude oil. FTIR–ATR and NMR results indicate the presence of a large number of polar components in the resins. High-resolution mass spectrometry showed that two resins contain a variety of heteroatom compounds and sulfur-containing heteroatom. The results indicated that these resins played a surprisingly inhibitory role in the hydrate formation kinetics; this was ascribed to the presence of the polar functional groups. The results also showed that the hydrate grew along the direction of gas flow. Notably, the presence of resins could prolong the induction time and lower the growth rate; this effect could be enhanced with the addition of resins containing more heteroatoms. This study filled the gap in the effect of natural resins on the hydrate formation kinetics and provided guidance on preventing hydrate plugging in oil and gas transport pipelines.

Effect of biochar aging in agricultural soil on its wetting properties and surface structure

Biochar wettability and ability to accumulate moisture inside the porous space are crucial for improving soil fertility, regulating soil water balance, and regulating nutrients. However, a long-term interaction of biochar with agricultural soils may drastically alter the wetting properties and, eventually, influence water holding capacity and the structure of soils. In this work, the structure and wetting properties of biochar samples after 6-year long exposure to a sandy loam Spodosol with a crop rotation and mineral fertilizers application were studied. It was found that the elemental composition of the aged biochars was richer and more "soil-like", which is explained by the presence of the mineral crust on the biochar surface. The temporal evolution of biochar in the soil without any mineral fertilizer application resulted in significant improvement of its surface wettability due to the effects of various environmental factors. The lateral surface of biochar after 6-year interaction with the soil changes into a loose porous layer in a form of grooved base filled with adherent mineral soil and clay particles. Contrary, the application of the mineral fertilizer to the soil resulted in decreased wettability of the biochar lateral surfaces due to a decrease in the polar component of surface energy and the crusting of the surface with fine material, which blocks the pore space of the biochar. As a result, water capacity of the biochar from the treatment with the fertilizer decreased compared to the biochar samples collected from the soil without the fertilizer application. The radial biochar surfaces of both types of samples collected from the soil were open vessels filled with soil particles that slow down complete wetting and water absorption. The treatment of the biochar samples with surfactants drastically increased wettability of lateral surface and water absorption capacity of control samples as compared to the samples collected from the soil. The obtained results support the idea that the hydrophilisation of biochar caused by the adhesion of soil particles and treatment of its pore surface with surfactants, can improve the water-holding capacity of the sandy loam Spodosol in the plant-available range of soil water.Graphical

Revealing the dependance of mechanical properties of asphalt binder on graphene size via multi-scale methods

Elucidating the specific interaction between graphene with various structures and asphalt is essential to promote the wide adoption of graphene modified asphalt for high-performance pavement engineering. Herein, the enhancement of modified asphalts with nano-sized graphene (NG) and micro-sized graphene (MG) were systematically investigated by using dynamic shear rheometer (DSR), atomic force microscopy (AFM) and molecular dynamics (MD) simulation at multi-scale levels. The results demonstrate that MG can significantly enhance the deformation resistance and low-temperature crack resistance of modified asphalt, compare with NG, and AFM confirm that MG can obviously affect the rearrangement of four components in asphalt to form a micellar structure with higher modulus and lower energy dissipation. MD simulation further verifies that the higher mechanical strength of large-sized graphene modified asphalt is attributed to the reduced slide movement of cavitation structures in asphalt, since the larger graphene not only has stronger π-π interaction with asphaltene and resin, but also induces one more specific interaction of hydrogen bonds (O-H···S) between these polar components. The coupling interaction facilitates the formation of more compact micelles, resulting in the improved mechanical properties of asphalt. The elucidation of graphene size effect on asphalt provides encouragement for understanding the enhancement of graphene modified asphalt.

The Design and Performance Evaluation of a 1550 nm All-Fiber Dual-Polarization Coherent Doppler Lidar for Atmospheric Aerosol Measurements

A 1550 nm all-fiber dual-polarization coherent Doppler lidar (DPCDL) was constructed to measure the depolarization ratio of atmospheric aerosols. In lidar systems, the polarization state of the laser source is typically required to be that of linearly parallel polarization. However, due to the influence of the fiber-optical transmission and the large-mode field output of the telescope, the laser polarization state changes. Hence, a polarizer was mounted to the emitting channel of the telescope to eliminate the depolarization effect. A fiber-optical polarization beam splitter divided the backscattered light into components with parallel and perpendicular polarization. The DPCDL used two coherent channels to receive each of these two polarization components. A calibration procedure was designed for the depolarization ratio to determine the differences in gain and non-responsiveness in the two polarization channels. The calibration factor was found to be 1.13. Additionally, the systematic error and the measured random error of the DPCDL were estimated to evaluate the performance of the system. The DPCDL’s systematic error was found to be about 0.0024, and the standard deviation was lower than 0.0048. The Allan deviations of a 1-min averaging window with a low SNR of 19 dB and a high SNR of 27 dB were 0.0104 and 0.0031, respectively. The random errors at different measured heights were mainly distributed below 0.015. To confirm the authenticity of the atmospheric depolarization ratio measured with the DPCDL, two field observations were conducted with the use of a co-located DPCDL and micro-pulse polarization lidar to perform a comparison. The results showed that the correlation coefficients of the aerosol depolarization ratios were 0.73 and 0.77, respectively. Moreover, the two continuous observations demonstrated the robustness and stability of the DPCDL. The depolarization ratios were detected in different weather conditions.

Femtosecond Laser-Induced Emission of Coherent Terahertz Pulses from Ruthenium Thin Films.

We demonstrate emission of electromagnetic pulses with frequencies in the terahertz (THz) range from ruthenium thin films through a second-order nonlinear optical process. Ruthenium deposited on different substrates showed different THz emission properties. We provide evidence that for Ru on glass above a certain power threshold, laser-induced oxidation occurs, resulting in an increased slope of the linear dependence of the THz electric field amplitude on pump power. The THz electric field is mainly polarized parallel to the sample surface, pointing in the same direction everywhere. In contrast to Ru on glass, the electric field amplitude of the THz pulses emitted by Ru on sapphire and on CaF2 shows a simple single linear dependence on pump power, and it is polarized orthogonal to the sample surface. In this case, thermal oxidation in an oven enhances the emission and introduces an additional polarization component along the sample surface. This component also points in the same direction everywhere on the surface, similar to the as-deposited Ru on glass. Although the precise THz generation mechanism remains an open question, our results show a strong correlation between the emission strength and the degree of oxidation. Furthermore, the results highlight the importance of the interfaces, i.e., both the choice of the substrate and the chemical composition of the top surface in THz emission experiments. Knowledge of the state of the sample surface is therefore crucial for the interpretation of THz emission experiments from (nonmagnetic) metal surfaces.

All-dielectric six-foci metalens for infrared polarization detection based on Stokes space.

The detection technology of infrared polarization has gained significant attention due to its ability to provide better identification and obtain more information about the target. In this paper, based on the expression of the full polarization state in Stokes space, we designed micro-nano metasurface functional arrays to calculate the polarization state of the incident light by reading the Stokes parameters (a set of parameters that describe the polarization state). Metalens with linear and circular polarization-dependent functions are designed based on the propagation and geometric phases of the dielectric Si meta-atoms in the infrared band, respectively. The device exhibits a high polarization extinction ratio. The influence of incident angle on polarization-dependent metalens is discussed, and the analysis of incident angle is of great significance for the practical application. An infrared six-foci metalens is proposed, each corresponding to the Poincaré sphere's coordinate component (a graphical polarization state method). By matching the six polarization components of the incident light and the Stokes parameters, the polarization detection function can be realized by calculating the polarization state of the incident light. There is a slight error between the theoretical value and the calculated value of the unit coordinate component of the Stokes parameters. At the same time, the intensity distribution of different incident light polarization azimuth angles and ellipticity angles on the focal plane agrees with the theory. The advantage of the device is that the polarization state of the incident light can be directly calculated without passing through other components. The six-foci metalens have potential applications in polarization detection and imaging, space remote sensing, etc.

Frequency‐Domain Dielectric Response of Insulating Paper with High Humidity

AbstractThe frequency‐domain dielectric spectroscopy (FDS) of humid insulating paper has been measured at different temperatures. The data show three independent dielectric processes: electrode polarization, hopping conductivity and interfacial polarization. The dielectric properties of humid insulating paper are composed of hopping conductivity and interfacial polarization, and its equivalent dielectric model can be represented by a Havriliak‐Negami (HN) relaxation branch parallel hopping conductivity. At high temperatures and low frequencies, the measured dielectric spectroscopy bends downward, which is caused by the electrode polarization. In this case, the equivalent dielectric model is composed of the body impedance of insulating paper and the electrode polarization in series. According to the equivalent dielectric model, the components of electrode polarization, hopping conductivity, and interface polarization can be separated, thereby eliminating the parasitic effect of electrode polarization on the dielectric properties of insulating paper. Both of hopping conductivity and interface polarization of insulating paper move toward high‐frequency direction with temperature increasing. For humid insulating paper with a moisture content of 5.9%, the activation energies of hopping conductivity and interface polarization are 1.18 and 0.99 eV, respectively. This difference in activation energies results in the inability of the spectrums of insulating paper to overlap with each other at different temperatures. Based on the insulating paper without oil immersion, the results obtained in this article are not affected by oil or oil‐immersion operations. This provides a reference for exploring the dielectric properties and physical mechanisms of oil‐paper composite insulation materials widely used in high‐voltage equipment. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

The efficacy of beeswax in extending frying life of sunflower oil and storage stability of fried potato chips

AbstractThis study was performed to investigate the impact of adding beeswax to sunflower oil on its frying life and the oxidative stability of the fried potato chips during storage. In this study, sunflower oil and its oleogels containing 2, 4, and 6/100 g(w/w) of beeswax were used in order to fry potato chips for 4 h each day for 4 days consecutively. Samples fried in sunflower oil absorbed the highest amount (37.0%) of oil compared to the lowest (32.9%) in 2% oleogel. The addition of beeswax did not negatively affect the color, texture, and sensory quality of potato chips. Based on the analysis of total polar components, changes in fatty acid composition, and p‐anisidine evaluation, the findings of this study indicate that the utilization of beeswax‐sunflower oil oleogel, particularly the 6% oleogel, may offer enhanced frying stability compared to sunflower oil. Moreover, chemical analyses of the potato chips stored for 30 days revealed that the control sample contained highest level of secondary oxidation products compared to the oleogels, indicating that fried potato chips in oleogels were more resistant to oxidation during storage. Therefore, beeswax can be considered as a natural preservative that improves the shelf life of fried potato chips as well as the frying stability of sunflower oil.

Three Orthogonal Polarization Distribution Mapping of the Tightly Focused Fields with a Dual‐Mode Waveguide Probe

AbstractStrongly confined electromagnetic (EM) fields generated by tightly focused light beams are applied widely in nano‐optics due to their vectorial characteristics. The inclusion of the longitudinal polarized component plays a crucial role in both the physical characteristics and practical uses of tightly focused vector beams. The acquisition of the distributions of the three orthogonal polarized components of these fields is advantageous for the comprehensive examination of their captivating physical phenomena and possible applications. However, this continues to pose a noteworthy obstacle, especially in the case of the fields that are generated by high numerical aperture objectives. A novel approach is proposed to quantifying the three mutually perpendicular polarizations simultaneously in the focal plane. The method utilizes a dual‐mode waveguide probe that is composed of a dielectric nanoparticle and a metal‐dielectric waveguide. This design allows for the simultaneous support of both transverse electric (TE) and transverse magnetic (TM) modes. Consequently, it enables the polarization recognition of scattering light in k‐space. Importantly, this method effectively eliminates any interference originating from the background light. The work involves an analysis of the theoretical notion of the probe and followed by experimental investigations. This approach holds promise for augmenting optical nanoscopy methodologies and their associated applications.

Microbacterium nymphoidis sp. nov. and Microbacterium festucae sp. nov., two novel species with high plant-promoting potential isolated from wetland plants in China.

Two novel plant growth-promoting, rod-shaped, Gram-positive and non-motile rhizobacteria, W1NT and W2RT, were isolated from wetland plants Festuca elata and Nymphoides peltatum, respectively, in China. The results of the 16S rRNA sequence alignment analysis showed that they were related to Microbacterium, with the highest similarity to Microbacterium ketosireducens (98.7 %) and Microbacterium laevaniformans (98.5 %) for strain W1NT, and to Microbacterium terricola (98.1 %) and Microbacterium marinum (98.0 %) for strain W2RT. Phylogenetic analyses based on 16S rRNA gene sequences and 92 conserved concatenated proteins suggested that the two strains belong to the genus Microbacterium and were placed in two separate novel phylogenetic clades. The genome sizes of the two strains were 3.2 and 3.7 Mb, and the G+C contents were 71.7 and 68.5 mol%, respectively. The comparative genome results showed that the average nucleotide identity values between W1NT and W2RT and other species ranged from 73.5 to 83.6 %, and the digital DNA-DNA hybridization values ranged from 19.7 to 26.8 %. These two strains show physiological and biochemical features that differ from those of closely related species. Rhamnose, galactose and glucose were present in the characteristic sugar fractions of strains W1NT and W2RT. The peptidoglycan of strains W1NT and W2RT contained the amino acids ornithine, alanine and aspartic acid. C15 : 0 anteiso, C17 : 0 anteiso and C16 : 0 iso were the predominant cellular fatty acids in W1NT and W2RT. Phosphatidylglycerol and diphosphatidylglycerol are major polar lipid components. Strain W1NT not only formed bacterial biofilms but also had the ability to solubilize phosphorus and produce indole-3-acetic acid. Strain W2RT had siderophore-producing and lignin-degrading properties. Based on their genetic and phenotypic characteristics, strains W1NT and W2RT were classified as novel bacteria in the genus Microbacterium and designated as Microbacterium festucae sp. nov. (type strain W1NT=ACCC 61807T=GDMCC 1.2966T=JCM 35339T) and Microbacterium nymphoidis sp. nov. (type strain W2RT=ACCC 61808T=GDMCC 1.2967T=JCM 35340T).

Multiwave Matrix Polarization Lidar

Remote control of the state of the atmosphere is an urgent problem nowadays. The problem of remote monitoring of the optical parameters of the atmosphere is solved using a matrix polarization lidar (MPL). The scattering matrix obtained from polarization measurements contains complete information on the scattering parameters in the atmosphere. The purpose of the present research is the derivation of the theory and description of methods for solving problems of practical implementation of the multiwave MPL (MMPL). The problem is considered within the framework of the concept of the unified methodological approach to polarization studies. The MMPL operation principle is based on simultaneous use for sensing of the first, second, and third harmonics of radiation of a widespread Nd:YAG laser. The basis for achieving this purpose is provided by new methods of optical selection of the polarization components of radiation received in the experiment, methods of conducting polarization studies, and new solutions in experimental data processing methods. It has been shown that this challenge can be solved within the framework of simple solutions. Thus, the proposed MMPL is structurally simple and compact and can be implemented in mobile polarization lidar systems.

Genotoxicity of chlorinated hydrophobic organic compounds extracted from a source of drinking water

As precursors of disinfection by-products (DBPs), sediment hydrophobic organic compounds (HPOCs) derived from six reservoirs along the Dongjiang River were chlorinated (Cl-WS) and then fractionated into two polar components (hydrophobic organic compounds (Cl-HOCs) and hydrophilic organic compounds (Cl-HICs)) by solid phase extraction. Based on Caco-2 cell exposure study, the genotoxicity of Cl-WS, Cl-HOCs and Cl-HICs was analyzed by reactive oxygen species (ROS) analysis, comet assay and ethoxyresorufin-O-deethylase assay. Protective effects of antioxidants (catalase, vitamin C and epigallocatechin 3-gallate (EGCG)) on genotoxicity of the chlorinated samples were investigated. The results showed that Cl-WS and its two fractions (Cl-HOCs and Cl-HICs) induced ROS, DNA damage and dioxin-like toxicity (TEQbio), and Cl-HICs were a major contributor to oxidative damage and TEQbio compared with Cl-HOCs. Antioxidants significantly reduced Cl-HOCs- and Cl-HICs-induced ROS, but had insignificant effect on DNA oxidative damage and TEQbio. In addition, EGCG showed higher efficacy in reducing DNA damage induced by Cl-HICs than by Cl-HOCs. To our knowledge, this is the first study to investigate the genotoxicity of Cl-WS and its two polar components in Caco-2 cells, as well as the protective effects of antioxidants on Cl-HOCs and Cl-HICs-induced ROS, DNA damage, and TEQbio. This study provides important toxicity information for water treatment industries in differentiating DBPs of different polarity.

Tunable Hairy and Crew‐Cut Supermicelles from Poly(N‐octyl glycine)‐Based Diblock Copolymer via a Hierarchical Assembly Strategy

AbstractFabrication of hierarchical superstructures by utilizing bioinspired polymeric materials shows great potential that has attracted considerable attention. A new hierarchical assembly approach has been developed to fabricate supramolecular structures in a one‐pot preparation from crystallizable polypeptoids‐based block copolymers. Herein, both hairy and crew‐cut supermicelles are reported by systematically tuning the temperature and solvent from a series of poly(ethylene glycol)112‐block‐poly(N‐octylglycine)n (PEG112‐b‐PNOGn) with different degrees of polymerization of PNOG. The incorporation of a third polar component poly(N‐allylglycine)‐graft‐COOH (PNAG‐g‐COOH) into the amphiphilic diblock copolymers can promote the formation of crew‐cut supermicelles owing to enhanced intermolecular interactions. It is demonstrated that both surface energy and crystallization energy are of great importance for the preparation of different types of supermicelles.

Effects of polar fractions on interfacial and bulk properties at the oil/carbonated aqueous solution interface: Insight from molecular dynamics simulation

This study utilized molecular dynamics simulations to understand the liquid/liquid interfaces in a natural environment involving carbon dioxide and various acidic components. The aim is to unravel the impact of polar fractions with various chemical structures and functional groups, namely benzoic acid, decanoic acid, phenol, and decanol, on the interfacial phenomena of the oleic phase (decane) in contact with water or CO2-rich water at the molecular resolution. The findings indicate that carbon dioxide molecules enrich at the decane/water interface before dissolving into the oleic phase. When polar molecules are introduced to the oleic phase, there is a competition between carbon dioxide and acidic components to accumulate at the interface. The functional hydrocarbon fractions displace carbon dioxide at the interface and bridge the oleic and aqueous phases, reducing interfacial tension. Polar components change the charge distribution of water molecules in the biphasic system, signifying that the organized water layer at the interface with the non-aqueous phase has been disrupted. In contrast to the polar molecules, the carbon dioxide tends to diffuse into the oleic phase and changes the bulk properties like oil fluidity. Accordingly, the fluidity of the decane exhibited significant enhancement by CO2 diffusion throughout the bulk oil phase, which might lead to substantial viscosity reduction.

Polarimetric measurement of non-depolarizing optical systems

The use of polarization measurements has become more common in recent years, as it gives more information than pure intensity measurements. Polarimetric components such as fixed or variable retarders and polarizers must be included in optical systems to obtain the polarization parameters required, and in many cases the optical system also includes other components such as relay and/or imaging optical systems. In this work we present a simple and robust method for the polarimetric characterization of non-depolarizing polarization components and other optical elements in the system, which does not require a full polarimeter. Since there is no depolarization, we represent the components as pure retarders with diattenuation and find their parameters (transmittance for the polarization components, angle of orientation of the fast axis, and retardance), from which we can retrieve their Mueller matrix. Our results show that the proposed method is accurate when compared with results obtained with a Mueller matrix dual-rotating retarder polarimeter calibrated using the eigenvalue calibration method, considered in this work as the gold standard, and is comparatively easier than the latter to implement, particularly for imaging polarimeters.

Formation of the mutagenic DNA lesion 1,N2-ethenoguanine induced by heated cooking oil and identification of causative agents

BackgroundThe DNA-damaging compounds in heated cooking oil were identified as guanosine adducts. Heated vegetable oil was subjected to deep-frying conditions at 170 °C for 45 min, reacted with isopropylidene guanosine (ipG) at pH 7.4, and the resulting compounds were separated by high-performance liquid chromatography (HPLC).ResultsTwo adducts, 8-hydroxy-ipG and 1,N2-etheno-ipG, were identified in the reaction mixture. One of the major components in heated cooking oil, 2,4-heptadienal (HDE), efficiently produced etheno-ipG from ipG in the presence of tBuOOH. An oxidized HDE solution was fractionated using HPLC to identify causative agents, and each fraction was tested for etheno-ipG formation. In addition to the known lipid peroxidation product, 4,5-epoxy-2-heptenal, two unknown polar components with potent etheno-ipG formation activity were discovered. Based on Mass and UV spectra, their structures were identified as 6-oxo- and 6-hydroxy-2,4-HDE. Similarly, 6-oxo- and 6-hydroxy-2,4- decadienal (DDE) were formed from 2,4-DDE. Significant amounts of 6-oxo- and 6-hydroxy-2,4-alkadienal were detected in the heated cooking oil. These compounds induced the formation of 1,N2-ethenoguanine in nucleosides and DNA, especially in the presence of tBuOOH. Moreover, the formation of 6-oxo- and 6-OH-HDE from 2,4-HDE was accelerated in the presence of hemin and tBuOOH.ConclusionThe results suggest that these compounds are not only generated during the oil heating process but also produced from 2,4-alkadienal through digestion under normal physiological conditions, especially after ingesting heme- and alkyl-OOH-containing diets. Moreover, these compounds can be formed within cells under oxidative stress, potentially linking them to gastrointestinal carcinogenesis.

Quantum mechanics based non-bonded force field functions for use in molecular dynamics simulations of materials and systems: The nitrogen and oxygen columns.

Accurate Force Fields (FFs) are essential for Molecular Dynamics (MD) simulations of the dynamics of realistic materials in terms of atomic-level interactions. The FF parameters of short-range valence interactions can be derived through Quantum Mechanical (QM) calculations on model systems practical for QM (<300 atoms). Similarly, the dynamic electrostatic interactions can be described with methods such as QEq or PQEq that allow charges and polarization to adjust dynamically. However, accurately extracting long-range van der Waals (vdW) interactions from QM calculations poses challenges due to the absence of a definitive method to distinguish between the different energetic components of electrostatics, polarization, vdW, hydrogen bonding, and valence interactions. To do this we use the Perdew-Burke-Ernzerhof flavor of Density Functional Theory, including empirical D3 vdW corrections, to predict the Equation of State for each element (keeping any covalent bonds fixed), from which we obtain the two-body vdW nonbond potential. Here, we extend these calculations to include non-bonded parameters for the N and O columns of the periodic table so that we now describe columns 15 (N), 16 (O), 17 (F), and 18 (Ne) of the periodic table. For these 20 elements, we find that the two-body vdW potentials can all be mapped to a single universal two-body curve, with just three scaling parameters: Re, De, and L. We refer to this as the Universal NonBond (UNB) potential. We expect this to be useful for new MD simulations and a helpful starting point to obtain UNB parameters for the remainder of the periodic table.