Ring Distribution Research Articles

Combined effects of engine characteristics and fuel aromatic content on polycyclic aromatic hydrocarbons and toxicity

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are harmful compounds because of their toxicity, adverse effects on human health, and threats to engine components (i.e. wetstacking). With the increased use of renewable fuels, it is imperative that the formation of PAHs be examined, in detail, with respect to the combustion characteristics and aromatic content of biofuels used in diesel engines. Since biodiesel is free of aromatic content in its chemical structure, this study provides comparative assessments of the PAHs, toxicity and regulated emissions of biodiesel (B100) and diesel fuel (D100), based on the fuel aromaticity and engine characteristics when used in two diverse engines. Results indicate that the use of B100 in both engines reduced total PAH emissions by 48.02% − 49.36% and PAH toxicity by 83.49% − 84.8% as compared to diesel fuel, which is a clear indication of the importance of the aromatic content of the base fuel on PAH formation and toxicity (i.e. aromatic-free fuel produces less PAH than diesel with high aromaticity). The aromatic ring distribution associated with B100 exhaust consisted of 50% two, 34% three and 16% four aromatic rings for the Onan engine, and 53% two, 32% three and 15% four aromatic rings for the Kubota engine. Benzo[a]pyrene, a five-ring PAH with great carcinogenic threat, was eliminated in both engines as a result of using B100. To demonstrate the significance of combustion processes on PAH formation, performances of the engines were compared and it was determined that the Kubota engine performed better for both fuels in reducing PAH emissions, due to such features as its injection system and combustion chamber design as compared to the Onan engine. Therefore, it has been concluded that PAH emissions and toxicity strongly depend on both the aromatic content and the combustion processes, as aromatic-free biodiesel significantly decreased PAHs along with additional reduction in PAHs and toxicity depending on the structural specifications of the diesel engine. Based on this study, aromaticity has been determined to be more effective than the type of engine in use for PAH reduction.

A Three‐Membered Diazo‐Aluminum Heterocycle to Access an Al=C π Bonding Species

Abstract[1+2] cycloaddition between a cyclic (alkyl)(amino)aluminyl anion (3) and diaryldiazomethane affords an AlN2three‐membered ring species (4). Compound (4) is thermally unstable and spontaneously releases N2gas under the mild reaction condition to generate an ion‐separated species5. An X‐ray study shows that the anionic part of5bears a considerable short exocyclic Al−C bond, and computational studies involving molecular orbital and natural bond orbital analysis indicate the Al=C π bonding character. The Al=C moiety of5undergoes intramolecular C−H activation. Moreover, reaction of5with a diazo compound leads to the reduction and complete cleavage of the N=N double bond.

A Three‐Membered Diazo‐Aluminum Heterocycle to Access an Al=C π Bonding Species

[1+2] cycloaddition between a cyclic (alkyl)(amino)aluminyl anion (3) and diaryldiazomethane affords an AlN2 three-membered ring species (4). Compound (4) is thermally unstable and spontaneously releases N2 gas under the mild reaction condition to generate an ion-separated species 5. An X-ray study shows that the anionic part of 5 bears a considerable short exocyclic Al-C bond, and computational studies involving molecular orbital and natural bond orbital analysis indicate the Al=C π bonding character. The Al=C moiety of 5 undergoes intramolecular C-H activation. Moreover, reaction of 5 with a diazo compound leads to the reduction and complete cleavage of the N=N double bond.

Coordination of Overcurrent Relay In Distribution System

The overcurrent phenomena are a dangerous condition that can be occurred in the electrical system and equipment. The condition of the overcurrent will cause the short-circuited current flows through the system and affect the other distribution line. The purpose of this study is to investigate the coordination of the overcurrent relay in different types of the distribution network which are radial distribution system, ring distribution system, and interconnected distribution system during line to ground fault occur at the bus. The generation of the overcurrent and directional overcurrent flow in the distribution network will damage the nearest equipment and reduce the power stability. The installation of the IDMT overcurrent relay in the distribution system will clear the faulty section from affecting the other distribution line. This protective device also operates to detect the abnormal condition with proper time current characteristic condition that involves the optimum time speed, accurate coordination, and sensitivity. The simulation of the IDMT overcurrent relay in the one-line diagram of the distribution network is executed by using ETAP software meanwhile the IDMT relay setting is calculated via MATLAB.

Investigation of the biochemical controls on mercury uptake and mobility in trees

Atmospheric elemental mercury (Hg(0)) enters plant stomata, becomes oxidized, and is then transferred to annual growth rings providing an archive of air Hg(0) concentrations. To better understand the processes of Hg accumulation and translocation, the foliage of quaking aspen and Austrian pine were exposed to Hg(0), and methylmercury (MeHg) or Me198Hg via roots, in controlled exposures during the summer. Isotopic measurements demonstrated, in a laboratory setting, that the natural mass-dependent fractionation observed was the same as that measured in field studies, with the lighter isotopes being preferentially taken up by the leaves. Hg was measured in plant tissues across seasons. Aspen trees moved Hg into new growth immediately after exposure, resorbed Hg in the fall, and then distributed Hg to new growth tissues in the spring. Austrian pine did not reallocate Hg. Mercury measured in aspen leaf fractions of trees exposed to Hg(0) demonstrated that 85 % of Hg was in the cell wall. It was also found that redox-active molecules, such as H2O2, could potentiate the release of cell wall-bound Hg from aspen leaves, providing a potential mechanism for remobilization. Regardless of the mechanism, the ability of aspen to reallocate Hg to new tissues indicates that Hg distribution in tree rings from aspen do not provide a reliable record of yearly changes in atmospheric Hg(0).

Scaling of Electron Heating by Magnetization During Reconnection and Applications to Dipolarization Fronts and Super‐Hot Solar Flares

AbstractElectron ring velocity space distributions have previously been seen in numerical simulations of magnetic reconnection exhausts and have been suggested to be caused by the magnetization of the electron outflow jet by the compressed reconnected magnetic fields (Shuster et al., 2014, https://doi.org/10.1002/2014GL060608). We present a theory of the dependence of the major and minor radii of the ring distributions solely in terms of upstream (lobe) plasma conditions, thereby allowing a prediction of the associated temperature and temperature anisotropy of the rings in terms of upstream parameters. We test the validity of the prediction using 2.5‐dimensional particle‐in‐cell (PIC) simulations with varying upstream plasma density and temperature, finding excellent agreement between the predicted and simulated values. We confirm the Shuster et al. suggestion for the cause of the ring distributions, and also find that the ring distributions are located in a region marked by a plateau, or shoulder, in the reconnected magnetic field profile. The predictions of the temperature are consistent with observed electron temperatures in dipolarization fronts, and may provide an explanation for the generation of plasma with temperatures in the 10s of MK in super‐hot solar flares. A possible extension of the model to dayside reconnection is discussed. Since ring distributions are known to excite whistler waves, the present results should be useful for quantifying the generation of whistler waves in reconnection exhausts.

Comparison of the shape of focal spots in terms of intensity and energy flux for a high-aperture zone plate and a spiral zone plate

Using a finite-difference time-domain method, it has been shown that focal spots generated when tightly focusing a linearly polarized Gaussian beam by a Fresnel zone plate (FZP) and when focusing a Gaussian beam with an embedded optical vortex by a spiral zone plate (SZP) have different patterns of the intensity and energy flux. The most significant differences are observed when the value of the topological charge (TC) is equal to three. The energy flux has an annular distribution when the Gaussian beam is focused by the FZP, while the SZP produces a field whose patterns of intensity and energy flux have three local maxima. The number of local maxima corresponds to the order of the SZP. At a certain distance from the focus, the petal structure of the intensity (and energy flux) changes to a ring distribution.

Research on Forward Problem of Rail Detection Based on Magnetoacoustic Coupling.

According to the characteristics of rail defects, a rail microcrack detection method based on magnetoacoustic coupling effect is proposed in this paper. Firstly, the basic principle of a rail microcrack detection method based on magnetoacoustic coupling effect is described, and then the model is analyzed theoretically. Through simulation calculation, the current density distribution and Lorentz force distribution generated by electromagnetic excitation, the motion characteristics of particles under Lorentz force and the sound field distribution characteristics of magnetoacoustic signals generated by Lorentz force are obtained. Finally, an experimental platform was set up and the steel ring model was preliminarily tested. The magnetic and acoustic signals of the two steel ring boundaries excited by an electromagnetic field were collected. These signals correspond to the position distribution of the steel ring. The state change of rail microstructure will cause a change in the conductivity characteristics of rail materials, and will affect the characteristics and distribution of sound pressure in the detection. Therefore, the detection method based on the magnetoacoustic coupling effect can detect the surface microcracks of high-speed rail. This method has great feasibility and development potential in the field of rail flaw detection.

Metagenetics of fairy rings reveals complex and variable soil fungal communities

Although fairy rings are widely observed, little is known of community processes associated with them. We studied fairy rings in natural grassland in Northern Mongolia, sampling soils outside (‘future’), directly under (‘present’), and within (‘past’) the rings, to represent different time stages during expansion of fairy rings. Soil DNA was extracted for amplicon sequencing of fungal ITS region. The present stage had reduced diversity, and the fungal community showed various differences, most strikingly an increase in the pathogenic fungus Fusarium/Gibberella in the present stage of many rings, and the saprotrophic fairy ring fungus Lepista luscina in several. However, no mushrooms of Lepista had been recorded from any of these rings in several years of observations. Known fairy ring fungi were not found in the present stage of every ring, even in some known to have previously displayed mushrooms of fairy ring species. It is possible, however, these fungi occurred or were more abundant at the unsampled leading edge of the ring. The increase in Fusarium/Gibberella is intriguing, but its importance – if any – is unclear. It is also unclear whether consortia of fungi or other microbes might be at work in these rings. The absence or low abundance of the previously reported fairy ring mushroom species suggests their presence is transient, with rapid replacement by other fungi. No differences in soil parameters were found between stages, except aluminium. There is a need for broader sampling, including analysis of non-fungal biota, towards understanding functional diversity of fairy ring fungi and consequences for plant communities.

A Parametric Study of Oxygen Ion Cyclotron Harmonic Wave Excitation and Polarization by an Oxygen Ring Distribution

A Parametric Study of Oxygen Ion Cyclotron Harmonic Wave Excitation and Polarization by an Oxygen Ring Distribution

Interaction of Ion Cyclotron Electromagnetic Wave with Energetic Particles in the Existence of Alternating Electric Field Using Ring Distribution

The elements that impact the dynamics and collaborations of waves and particles in the magnetosphere of planets have been considered here. Saturn’s internal magnetosphere is determined by substantiated instabilities and discovered to be an exceptional zone of wave activity. Interchanged instability is found to be one of the responsible events in view of temperature anisotropy and energization processes of magnetospheric species. The generated active ions alongside electrons that constitute the populations of highly magnetized planets like Saturn’s ring electron current are taken into consideration in the current framework. The previous and similar method of characteristics and the perturbed distribution function have been used to derive dispersion relation. In incorporating this investigation, the characteristics of electromagnetic ion cyclotron wave (EMIC) waves are determined by the composition of ions in plasmas through which the waves propagate. The effect of ring distribution illustrates non-monotonous description on growth rate (GR) depending upon plasma parameters picked out. Observations made by Cassini found appropriate for modern study, have been applied to the Kronian magnetosphere. Using Maxwellian ring distribution function of ions and detailed mathematical formulation, an expression for dispersion relation as well as GR and real frequency (RF) are evaluated. Analysis of plasma parameters shows that, proliferating EMIC waves are not developed much when propagation is parallelly aligned with magnetosphere as compared to waves propagating in oblique direction. GR for the oblique case, is influenced by temperature anisotropy as well as by alternating current (AC) frequency, whereas it is much affected only by AC frequency for parallel propagating waves.

Effect of methyl substituents, ring size, and oxygen on bond dissociation energies and ring-opening kinetics of five- and six-membered cyclic acetals

The demand for clean and highly efficient fuels stimulates the development of novel fuels for the next generation. With the emergence of new catalytic methods, the selective synthesis of cyclic acetals made them promising fuel candidates. The present work provides systematic and consistent calculations of bond dissociation energies for 1,3-dioxolane and 1,3-dioxane and their substituted derivatives. Rate constants of subsequent ring-opening reactions of the formed fuel radicals have been calculated to facilitate the understanding of initial fuel consumption pathways. We found that the CH bond on the carbon that is in between two oxygens will always be the weakest bond to be broken. The inclusion of two oxygens in the ring slightly changes the strain in the ring structure. However, the trend that the BDEs increase from five to six-membered ring species still exists in cyclic acetals. The reason is a smaller eclipsing strain in the five-membered radicals relative to the parent molecules. For the subsequent ring-opening reactions of the formed radicals, the radical site and the position of the substitution have a major impact. The results of our study facilitate a deeper understanding of the effect of methyl substituents, ring size, and oxygen on the reactivity of five- and six-membered cyclic acetals as well as provide accurate kinetic data for the mechanism development of these potential fuels.

Interfacial characterization in defective graphene/PET substrate structure through traction separation models: A molecular dynamics study

Among various graphene-based flexible electronic devices, the graphene/polymer substrate is one of the most common microstructures. Its interfacial mechanical properties directly determine the performance and reliability of these devices. Accordingly, the interaction between single-layer two-dimensional material such as graphene and polymer substrate has become an urgent research field in the manufacture and application of flexible electronic devices. In this study, traction-separation (T–S) models are established to study the interfacial mechanical behaviors of graphene/polyethylene terephthalate (PET) substrate structures using molecular dynamics (MD) simulations. The calculated interface parameters are verified by simulating the blister test with MD simulation and finite element analysis (FEA). Two common types of defects (Stone-Wales (S–W) and single vacancy (S–V)) are considered. By monitoring the aromatic ring distribution (order parameter and concentration) in PET substrate, the results reveal that under the normal loading, the S-W defect in graphene enhances the interfacial strength, while the separation energy is not sensitive to the existence of the S–W defect. The S–V defect in graphene degrades both the normal interfacial strength and separation energy owing to the loss of carbon atoms. Under the shear loading, it is found that the surface roughness of graphene caused by defects is an essential factor affecting the interfacial shear properties at the nanoscale. In addition, the results indicate that a low-concentration S–V defect can increase the surface roughness of graphene to obtain stronger mechanical interlocking, thereby enhancing the interfacial shear properties.

Influence of alkali metal Na on coal-based soot production

This work aims to investigate the effects of Na on the characteristics of coal-derived soot. Soot, which has long been regarded as an unwelcome source of air pollution, has been classified as a pollutant. However, with the proposed clean and efficient utilization of coal, soot has been found to be effectively inhibited by adding metal catalysts and changing the reaction environment, and it can even realize the transformation of pollutants to functional materials. To understand the effect on physiochemical properties, pyrene was used as a coal tar substitute, and the structural transformation of soot was thoroughly investigated by DFT calculation method in combination with elemental analysis, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The presence of Na changed the π electron distribution of benzene ring, promoted the dehydrogenation condensation and oxidation exfoliation of the surface microchip layer, and accelerated the condensation of PAHs and the formation of five-membered ring in the microchip layer. Na participates in the oxidation and growth process of soot, which can regulate the micromorphology of soot. With the participation of Na, the diameter of soot particles decreases, the microcrystal length and curvature become larger, and the internal holes increase.

What Is the Smallest Zeolite That Could Be Synthesized?

Zeolites with a few unit cells are promising as catalyst and adsorbents. The quest to synthesize the smallest zeolites has recently resulted in 4 to 8 nm nanozeolites, about 2 to 4 unit cells. These findings pose the question of what is the smallest zeolite that could be obtained by hydrothermal synthesis. Here we address this question using molecular simulations and thermodynamic analysis. The simulations predict that amorphous precursors as small as 4 nm can crystallize zeolites, in agreement with the experiments. We find that interfacial forces dominate the structure of smaller particles, resulting in size-dependent compact isomers that have ring and pore distributions different from open framework zeolites. The instability of zeolites smaller than 3±0.5 nm precludes a classical mechanism of nucleation from solution or through assembly of small nanoslabs.

What Is the Smallest Zeolite That Could Be Synthesized?**

AbstractZeolites with a few unit cells are promising as catalyst and adsorbents. The quest to synthesize the smallest zeolites has recently resulted in 4 to 8 nm nanozeolites, about 2 to 4 unit cells. These findings pose the question of what is the smallest zeolite that could be obtained by hydrothermal synthesis. Here we address this question using molecular simulations and thermodynamic analysis. The simulations predict that amorphous precursors as small as 4 nm can crystallize zeolites, in agreement with the experiments. We find that interfacial forces dominate the structure of smaller particles, resulting in size‐dependent compact isomers that have ring and pore distributions different from open framework zeolites. The instability of zeolites smaller than 3±0.5 nm precludes a classical mechanism of nucleation from solution or through assembly of small nanoslabs.

Spectroscopic Detection of Cyano-Cyclopentadiene Ions as Dissociation Products upon Ionization of Aniline.

The H-loss products (C6H6N+) from the dissociative ionization of aniline (C6H7N) have been studied by infrared predissociation spectroscopy in a cryogenic ion trap instrument at the free electron laser for infrared experiments (FELIX) laboratory. Broadband and narrow line width vibrational spectra in the spectral fingerprint region of 550–1800 cm–1 have been recorded. The comparison to calculated spectra of the potential isomeric structures of the fragment ions reveals that the dominant fragments are five-membered cyano-cyclopentadiene ions. Computed C6H7N•+ potential energy surfaces suggest that the dissociation path leading to H loss starts with an isomerization process, following a similar trajectory as the one leading to HNC loss. The possible presence of cyano-cyclopentadiene ions and related five-membered ring species in Titan’s atmosphere and the interstellar medium are discussed.

Physical and Chemical Properties of Coal Gasification Fine Slag and Its Carbon Products by Hydrophobic-Hydrophilic Separation.

Coal gasification fine slag is a kind of solid waste with low resource utilization rate. The complex embedding of residual carbon and inorganic minerals (ash materials) is the main reason restricting the efficient resource separation and utilization of residual carbon or ash materials. Hydrophobic–hydrophilic separation (HHS) is a separation technology in which mineral particles with different surface hydrophobicity values are enriched in the water phase and oil phase under the action of mechanical stirring. The water on the surface of hydrophobic particles is replaced by the oil phase to form flocs, which are enriched in the hydrophobic liquid phase, while hydrophilic particles are dispersed into the aqueous phase. In this study, the HHS process was used to separate the carbon/ash from the fine gasification slag produced by a Shenning gasifier, Texaco gasifier, and GSP gasifier of Ningxia Coal Industry Co., Ltd. The physicochemical properties of the original sample and the residual carbon products obtained by hydrophobic–hydrophilic separation were analyzed. The results show that HHS can separate the carbon/ash in the three kinds of fine slag to varying degrees. The carbon element is enriched into the hydrophobic phase to form the concentrates, while the silicon element, oxygen element, and metal element enter the tailings. The spherical ash with different particle sizes distributed on the surface of residual carbon and the gap of the matrix is basically removed, while the ash in the carbon–ash melt is difficult to remove. The ash contents of the concentrate and tailings of fine slag of the Shenning gasifier are 22.58 and 96.28%, respectively, which reach the best ash index compared with that of the other two gasifiers. From the change of mineral surface properties after HHS, the distribution of oxygen-containing groups, benzene rings, Si–O, and clay minerals or carbonate minerals in the three kinds of fine slag residual carbon products is basically similar. Compared with the other two gasifier products, the GSP gasifier concentrate has a larger specific surface area and less ash material, more amorphous carbon structures (less graphitic), and more active sites, resulting in a stronger combustion activity.

Effects of physical and chemical aging on polycyclic aromatic hydrocarbon (PAH) content and potential toxicity in rice straw biochars.

Polycyclic aromatic hydrocarbons in biochars threaten their environmental application. The aging process may affect the concentration of PAHs, potential toxicity, and the properties of biochar. In this study, the aged biochars were obtained by simulated physical aging method (freeze-thaw treatment) and chemical aging method (H2O2 chemical oxidation). The PAH contents in biochars were measured, and their potential toxicity was assessed. Meanwhile, the influence of aging process on the physicochemical properties of biochar was also investigated. This study shows that the change of PAH content of aged biochars depended on pyrolysis temperature, ambient temperature, and oxidant concentration. Furthermore, physical and chemical aging process influenced the distribution of different ring PAHs in biochars. High-ring-number PAHs (four, five, six-ring PAHs) appeared in some aged biochar. Aging at ±20 °C and 0.01 M H2O2 increased the toxic equivalent quantity of all biochars which may be attributed to the change of the physicochemical properties influencing the different PAH ring distribution in biochars. The contribution of PAHs with different rings to TEQ varied in pristine and aged biochars. Physical and chemical aging process significantly affected the properties of biochars, such as element content, ash content, surface area, pore volume, pH, functional groups, and surface morphology. Correlation analysis confirmed that surface area and pore volume are dominant factors determining the PAH content in the biochars. Therefore, the aging process indeed affected the PAH concentration and toxicity of PAHs in biochar. Assessing PAH behavior in biochar over long timescales should not be overlooked.

Effect of the Relativistic Electron Beam on Propagating Whistler-Mode Wave for Ring Distribution in the Saturn Magnetosphere

Cassini and many investigators reported whistler chorus near Saturn equatorial plane moving outwards. Whistler can propagate when going to high latitude and can alter its characteristics while interacting resonantly with available energetic electrons. Here investigating wave for a relativistic beam of the electron. It is observed and reported by Cassini Magnetospheric Imaging Instrument (MIMI) that inward radial injection of highly energetic particles is most dominant in Saturn intrinsic magnetosphere. Within this paradigm, an empirical energy dispersion relation for propagated whistler-mode oscillations in quasi Saturn magnetospheric plasma from such a non-monotonous ringed distribution function has been established. The kinetic approach and method of characteristics methodologies were used in the computations, which have been shown to be the best for building perturbed plasma states. The perturbed distribution function was estimated using the unperturbed particle routes. The ring distribution function was used to construct an unexpected growth rate expression for relativistic plasma in the inner magnetosphere. The results from the Saturn magnetosphere have been calculated and interpreted using a range of parameters. Temperature heterogeneity was shown to be a significant source of free energy that aided the propagation of a whistler-mode wave. By raising the peak value, the bulk injection of energetic hot electron injection impacts the growth rate. Growth was also demonstrated to be accelerated when the propagation angle increased. The research contributes to a better understanding of the relationship between wave and particle emissions and VLF emissions on a large scale.