Reactive Mixture Research Articles

Molecular Structure, Electronic Properties, Reactivity (ELF, LOL, and Fukui), and NCI-RDG Studies of the Binary Mixture of Water and Essential Oil of Phlomis bruguieri.

Essential oils are volatile oil-like liquids with a characteristic strong smell and taste. They are formed in plants and are then extracted. Essential oils have extremely strong physiological and pharmacological properties, which are used in the medicine, cosmetics, and food industries. In this study, the molecules caryophyllene oxide, β-pinene, 1,8-cineol, α-cubebene, and β-caryophyllene, which are the molecules with the highest contents in the essential oil of the plant mentioned in the title, were selected and theoretical calculations describing their interactions with water were performed. Because oil-water mixtures are very important in biology and industry and are ubiquitous in nature, quantum chemical calculations for binary mixtures of water with caryophyllene oxide, β-pinene, 1,8-cineol, α-cubebene, and β-caryophyllene were performed using the density functional theory (DFT)/B3LYP method with a basis of 6-31 G (d, p). Molecular structures, HOMO-LUMO energies, electronic properties, reactivity (ELF, LOL, and Fukui), and NCI-RDG and molecular electrostatic potential (MEP) on surfaces of the main components of Phlomis bruguieri Desf. essential oil were calculated and described.

MnFe2O4-based spinels by mechanochemical and thermochemical reaction of siderite and MnO2 powder mixtures

The manganese ferrite has been processed by mechanosynthesis, using reactive siderite and MnO2 powder mixtures, with and without subsequent heat treatment. Taguchi planning was used to assess the impact of milling conditions (rotational speed and time) and subsequent calcination temperature on conversion of precursors, based on integrated intensities of the main XRD peaks of precursor phases FeCO3 (104) and MnO2 (110), and spinel phase (311), using Ni as internal pattern. Thermogravimetry provided additional information on the residual contents of reactants in the as-milled samples. The best conditions for complete conversion to spinel phase of as-milled samples were obtained by milling at 650 rpm, for 6 h (I311,sp/I111,Ni=2.41), and for calcined samples were obtained after milling at 650 rpm, for 3 h, and calcination at 650 °C (I311,sp/I111,Ni=2.35). The impact of processing conditions on structural features of the spinel phase was accounted by the contributions to variance of intensity of its (311) reflection, which were 90% ascribed to rotational speed and only 4% ascribed to milling time, for as-milled samples, or 58%, 15% and 16% ascribed to rotational speed, milling time and calcination temperature, for calcined samples. Readier conversion of FeCO3 relative to MnO2 occurred during the milling stage, at low or intermediate rotational speed, with impact on Mn:Fe ratio in the spinel phase, as revealed by changes in lattice parameter of as-milled samples, in the range of 0.8424–0.8464 nm. Subsequent calcination minimized or eliminated traces of secondary phases. The incorporation of magnesium oxide and possibly other secondary components of the siderite precursor also induced structural changes in the resulting spinel phase, mainly in calcined samples (ao = 0.8370–0.8434 nm). Partial oxidation also contributed to structural changes in calcined samples, as revealed by differences between samples calcined in inert and oxidising atmospheres.

Paper in Science describes low-temperature upcycling of polyolefins into liquid alkanes via tandem cracking-alkylation

A team of researchers have found a way to cleave the carbon-carbon bonds in polyolefin waste at temperatures below 100°C by using a reactant catalyst mixture.

Directing the pore size of rigid polyurethane foam via controlled air entrainment

The interest in polyurethane rigid (PUR) foams as potent thermally insulating materials for a wide range of applications continues to grow as the minimization of CO2 emissions has become a global issue. Controlling the thermal insulation efficiency of PUR foams starts with the control of their morphology. Although the presence of micrometric air bubbles originating from air entrainment during the blending of the PU reactive mixture has been shown to influence the final PUR foam morphology, detailed experimental investigations on how exactly they affect the final PUR foam pore size are still lacking. To fill this gap, we use a double-syringe mixing device, which allows to control the number of air bubbles generated during a first air entrainment step, before using the same device to blend the reactive components in a sealed environment, avoiding further air entrainment. Keeping all experimental parameters constant except for the air bubble density in the reactive mixture, we can correlate changes of the final PUR foam morphology with the variation of the air bubble density in the initially liquid reactive mixture. Our results confirm recent findings which suggest the presence of two different regimes of bubble nucleation and growth depending on the presence or absence of dispersed air bubbles in the liquid reactive mixture. Our study pushes those insights further by demonstrating an inverse relation between the air bubble density in the liquid reactive mixture and the final pore volume of the PUR foam. For example, at constant chemical formulation and blending conditions, we could vary the final pore size between 400–1600 μm simply by controlling the amount of pre-dispersed air bubbles within the system. We are confident that the presented approach may not only provide a valuable model experiment to scan formulations in R&D laboratories, but it may also provide suggestions for the optimization of industrial processes.

Low-temperature upcycling of polyolefins into liquid alkanes via tandem cracking-alkylation.

Selective upcycling of polyolefin waste has been hampered by the relatively high temperatures that are required to cleave the carbon-carbon (C-C) bonds at reasonably high rates. We present a distinctive approach that uses a highly ionic reaction environment to increase the polymer reactivity and lower the energy of ionic transition states. Combining endothermic cleavage of the polymer C-C bonds with exothermic alkylation reactions of the cracking products enables full conversion of polyethylene and polypropylene to liquid isoalkanes (C6 to C10) at temperatures below 100°C. Both reactions are catalyzed by a Lewis acidic species that is generated in a chloroaluminate ionic liquid. The alkylate product forms a separate phase and is easily separated from the reactant catalyst mixture. The process can convert unprocessed postconsumer items to high-quality liquid alkanes with high yields.

Characteristics of rotating detonation wave fueled by liquid kerosene with increasing equivalence ratios

To investigate the characteristics of rotating detonation waves fueled by liquid kerosene with increasing equivalence ratios, the experiments were performed through increasing the supply of liquid kerosene under three different mass flow rates of oxidizer. Various mode transitions were realized, including transition from unstable detonation to stable single-wave mode, transition from unstable detonation to stable double-wave mode and transition from double-wave mode to single-wave & double-wave hybrid mode. The results demonstrate that the increase of equivalence ratios leads to the improvement of mixture reactivity under lean-fuel limit, which enhances the propagation stability and pressure peak of rotating detonation waves, and then results in the transition from unstable detonation to a stable propagation mode. In addition, when the mass flow rate of oxidizer is approximately 1100 g/s, the transition from double-wave mode to single-wave & double-wave hybrid mode is observed by increasing the equivalence ratio from 0.6 to 0.93. It is concluded that the mutation of dynamic balance between the RDW and injection plenum caused by the increasing of equivalence ratio is one of the reasons inducing the mode transition. This work illustrates the feasibility of modulating the propagation mode in rotating detonation waves fueled by liquid kerosene, and promotes the application of rotating detonation engine.

Formation of TiB2-MgAl2O4 Composites by SHS Metallurgy.

TiB2-MgAl2O4 composites were fabricated by combustion synthesis involving metallothermic reduction reactions. Thermite reagents contained Al and Mg as dual reductants and TiO2 or B2O3 as the oxidant. The reactant mixtures also comprised elemental Ti and boron, as well as a small amount of Al2O3 or MgO to serve as the combustion moderator. Four reaction systems were conducted and all of them were exothermic enough to proceed in the mode of self-propagating high-temperature synthesis (SHS). The reaction based on B2O3/Al/Mg thermite and diluted with MgO was the most exothermic, while that containing TiO2/Al/Mg thermite and Al2O3 as the diluent was the least. Depending on different thermites and diluents, the combustion front temperatures in a range from 1320 to 1720 °C, and combustion wave velocity from 3.9 to 5.7 mm/s were measured. The XRD spectra confirmed in situ formation of TiB2 and MgAl2O4. It is believed that MgAl2O4 was synthesized through a combination reaction between Al2O3 and MgO, both of which can be totally or partially produced from the metallothermic reduction of B2O3 or TiO2. The microstructure of the TiB2-MgAl2O4 composite exhibited fine TiB2 crystals surrounded by large densified MgAl2O4 grains. This study demonstrated an energy-saving and efficient route for fabricating MgAl2O4-containing composites.

Al/SnO2 Nanothermite ESD Desensitization by Means of the Elaboration of Tailored SnO2-Polypyrrole Composites.

Incidents can occur when handling energetic materials (EMs) due to their sensitivity to external stimuli. Mechanical (friction, impact) and electrical (electrostatic discharge (ESD)) stimuli can trigger involuntary ignition of EMs. Nanothermites, defined as highly reactive mixtures of a metal and a metal oxide, show interesting reactive properties (high temperature/amount of heat). However, their extreme sensitivity to ESD is a significant drawback in their development. With a sensitivity threshold of lower than a millijoule and considering the human body capacity discharge is a few tens of millijoules, the handling of such energetic mixtures is extremely hazardous. ESD desensitization is therefore of crucial importance for the use of these materials. To achieve this goal, polypyrrole (PPy) conductive polymer was used as an additive within an Al/SnO2 energetic formulation. This polymer is able to easily conduct the electrostatic charges, which is useful to avoid an ignition after a spark stimulus. PPy was added to the nanothermite through the elaboration of SnO2-PPy composites. Delaying the SnO2 introduction time during pyrrole's polymerization (t = 0, 1, 24 h) changed the microstructures of the composites. The various SnO2-PPy composites highlighted that the additive's distribution within the composite is a key component for the modulation of ESD sensitivity. For example, this threshold is higher for a nanothermite formulated with the composite elaborated at t = 0 h (96.5 mJ with 7.5 vol % of polymer) than a composition based on the composite at t = 24 h (16.9 mJ with 8.2 vol % of polymer). Meanwhile, the reactive properties are decreased. The loss of reactivity (e.g. combustion speed) was explained by the thermal insulating property of the additive. Overall, the aim of this study is to help in the understanding of ESD desensitization of nanothermites in order to make them safer for operators and adapted to the required applications.

Data-driven framework for input/output lookup tables reduction: Application to hypersonic flows in chemical nonequilibrium

In this paper, we present a novel model-agnostic machine learning technique to extract a reduced thermochemical model for reacting hypersonic flows simulation. A first simulation gathers all relevant thermodynamic states and the corresponding gas properties via a given model. The states are embedded in a low-dimensional space and clustered to identify regions with different levels of thermochemical (non)-equilibrium. Then, a surrogate surface from the reduced cluster-space to the output space is generated using radial-basis-function networks. The method is validated and benchmarked on a simulation of a hypersonic flat-plate boundary layer with finite-rate chemistry. The gas properties of the reactive air mixture are initially modeled using the open-source Mutation++ library. Substituting Mutation++ with the light-weight, machine-learned alternative improves the performance of the solver by 50% while maintaining overall accuracy.

Comparative Assessment of the Dyeing Process for Pristine and Modified Cotton Fabrics towards the Reduction of the Environmental Fingerprint

Though an important and chronic source of dyes released to the environment, the determination of the release of dyes that occurs during household or industrial washing is usually disregarded. The main scope of this study is to reveal the extent of dye release through washing, and to understand if the modification of cotton fabrics with cationic polymers could reduce it. Modified cotton fabrics, dyed with Acid Blue 281 (AB) or by a mixture of the reactive dyes Novacron Yellow S-3R (NY), Novacron Ruby S-3B (NR) and Novacron Dark Blue S-GL (NDB), underwent a certified washing process. The dyed fabrics were analyzed colorimetrically, while the washing waters were analyzed spectroscopically, via UV/Vis absorption and surface enhanced Raman scattering (SERS). In the modified fabrics dyed with the acid dye, an increased dye uptake was noticed that exhibited a color intensity of K/S~16, compared to K/S~0.45 of the unmodified fabrics. The corresponding normalized dye release (dye concentration/color intensity factor) in the wash water was ~1.6 for the modified fabrics, compared to ~6.5 in the case of the unmodified fabrics, indicating the significance of cotton modification on both the dye uptake and dye release during washing. In the fabrics dyed with a mixture of selected reactive dyes, the color uptake of modified (K/S~10) was also increased compared with unmodified fabrics (K/S~4.5). An important observation, is that in the case of the dyeing of the reactive dyes mixture, a selectivity on the part of the dye uptake was noticed, since the contribution of NY (yellow) is higher compared to that of the blue (positive value of color indicator coordinate (b)); however, this also resulted in an increased NY dye release during washing. The findings of this study could contribute to the dye release problem control due to fabric washing, and to the understanding of any potential selectivity on the part of dye–cotton interactions.

The critical role of swirl in high-specific-output diesel engines

In-cylinder flows are critical for the understanding of the combustion process in internal combustion engines. Although swirl flow has been extensively employed as the primary in-cylinder flow motion in diesel engines, it is usually accompanied with reduced intake mass, and the necessity and the role of swirl flow in high-specific-output diesel engines still remain inadequately understood. In this work, the combustion process of a high-specific-output diesel engine is numerically investigated under different swirl ratios (SR). Results show that the indicated work exhibits a nonmonotonic variation of “increase–decrease” with increasing SR, peaking at SR = 1 with the shortest combustion duration yet slightly higher heat loss compared to the non-swirl condition. The introduction of swirl is capable of reducing high-equivalence-ratio regions through enhanced transport and turbulent diffusion, while the spray-spray interaction may be too strong to yield a rich region in the central cylinder when the swirl is excessively high. The chemical reaction pathway analysis indicates that a moderate swirl ratio could promote mixing, yielding an improved utilization of fresh O2 that further affect the reactions. Specifically, the highly reactive mixture enlarges the radical pool and yields a higher reaction rate during the mixing-controlled combustion stage; While an overlarge swirl ratio may cause excessive mixing, leading to reduced local availability of fresh O2 in the mixing-controlled combustion stage, thereby suppressing the oxidation of small molecule hydrocarbon and hence reducing the global heat release rate. Compared to the spray-induced turbulent mixing for the non-swirl case, the turbulence intensity is significantly increased through swirl-spray interaction under a moderate SR, which could preserve throughout late-cycle combustion and yield improved soot oxidation rate, while an excessive swirl would trap some soot within the central cylinder region and suppress late-cycle soot oxidation. According to the present results, solely high-pressure injection is not sufficient to control the combustion, particularly due to the poor late-cycle mixing and combustion, and an adequate swirl flow is still indispensable in high-specific-output diesel engines.

Experimental investigation on the impact of NOx emission in CI engine fueled with rapeseed biodiesel with antioxidant additives

The proposed research aims to investigate the impact of an oxidant, l-ascorbic acid, on the performance and exhaust of a diesel engine that drives on neat rapeseed methyl ester-based oil (RSOME). The antioxidant is supplemented with rapeseed oil methyl ester in a range of amounts (100–400 mg). This research revealed that, without altering the engine, the reactive additives mixture (MERSO + LA300) substantially lowered the NOX and HC emissions of methyl ester in rapeseed oil-fueled engines.

Study of the Properties of YBCO Superconductor Compound in Various Preparation Methods: A Short Review

Superconductors have entered into many applications and advanced technological fields, due to their excellent properties identified by zero resistance and expelling the magnetic field applied to them. Superconductivity is a viable technology to prevent energy losses contributed by electrical resistivity. Also, the magnetic flux is repelled entirely out of the body of superconducting material which makes the Meissner Effect. High-Temperature Superconductors (HTS) have become the focus of researchers and scientists. This is because it uses liquid nitrogen "LN" in cooling, which gives it significant critical temperatures compared to traditional materials based on liquid helium "LHe" in cooling. From this point of view, began to employ these materials in most disciplines and modern technologies. In this article, the phenomenon of Superconductivity will define with explain its most prominent characteristics and focus on the preparation of the HTS (Yttrium-Barium-Copper-Oxide) compound (Abbreviated as YBCO) in different methods "The Sol-Gel and Citrate Pyrolysis Methods", to creating ultrafine superconducting (Y-123) powders. Generally known that by adopting any preparation technique, the superconducting transition temperature (Tc) value of ≈ 92 K could be achieved in the bulk samples. The Citrate Pyrolysis method is a unique route to prepare reactive precursor mixtures through an ignition process of a concentrated aqueous solution including metallic ions of stoichiometric composition. This procedure enables to synthesize of highly homogeneous and fine powders for functional materials, in comparison to the Sol-gel technique.

Flexible nanoscale co‐continuous structures prepared by controlled crazing of ethylene‐octene elastomers and in‐situ polymerization of conductive networks

AbstractAn approach based on controlled crazing and post‐polymerization was used to incorporate a nanoscaled conductive co‐continuous network into commercial ENGAGE™ Polyolefin Elastomers (POEs). Three POE films of differing crystallinity and phase morphology were stretched in a reactive mixture of acrylic polymerization precursors that possessed an affinity for the olefinic materials and acted as a surface‐active agent for craze promotion. As a result, a rigid acrylic hydrogel phase was grown in the void space associated with crazing, which prevented the formed channels from collapsing after mechanical stresses were removed. The hydrogel phase offered ion conductivity properties to the POE. Simply replacing the acrylic monomer with an aniline emulsion for polymerization did not lead to the same outcome in terms of a continuous network; the materials became insulative after the removal of mechanical stresses due to fragmentation of the polyaniline channels from the unrestrained elastic relaxation of the POE. This problem was overcome by solution‐casting POE with polycaprolactone (PCL) into films and, subsequently, partially dissolving and leaching PCL from the blend while a sample was stretched in an aniline emulsion medium containing formic acid. The residual PCL left in the crazes reinforced the polyaniline to prevent fragmentation, allowing the formation of a highly electron‐conductive secondary phase.

Application of the TNO multi-energy and Baker-Strehlow-Tang methods to predict hydrogen explosion effects from small-scale experiments

Analytical models or abacus are of importance to predict explosion effects in open and congested areas for industrial safety reasons. The goal of this work is to compare overpressure and flame speed values of small-scale deflagration experiments to predicted values from the TNO multi-energy (TNO ME) method and the Baker-Strehlow-Tang (BST) method. Experiments were performed in cylindrical congested volumes of hydrogen – air mixtures varying from 1.77 L to 7.07 L. The reactivity was controlled by the equivalence ratio of hydrogen-air mixtures, ranging from 0.5 to 2.5. The congestion was realized with varying numbers of grid layers and configurations. The influence of the obstacle density and the importance of the mixture reactivity to choose the strength index in order to predict the effects of an explosion has been highlighted for the TNO ME method. Predictive flame speed values from the BST method are in accordance with almost half of the experimental results and the method is conservative in most tested configurations. The use of the TNO ME method has been validated on a small-scale experiment to predict maximal overpressures generated by the deflagration of medium and large-scale H2/air clouds.

Lectin Purification through Affinity Chromatography Exploiting Macroporous Monolithic Adsorbents

Growing medical, engineering, biochemical, and biological interest has led to a steady pace of research and development into polymeric monolithic structures with densely interconnected pores for purifying bio compounds. Cryogels, which are generated by freezing a reactive polymerization mixture, are highlighted due to their versatility and low relative cost as macroporous, polymeric, monolithic adsorbents. The conversion of cryogels into affinity adsorbents is one possible alternative to their optimal application. Some of the most often utilized supports for immobilizing particular ligands are monolithic columns manufactured with epoxy radicals on their surfaces. The purification of biomolecules with a high degree of specificity, such as lectins and glycoproteins with an affinity for glycosylated groups, has garnered interest in the use of fixed non-traditional beds functionalized with ligands of particular interest. The interaction is both robust enough to permit the adsorption of glycoproteins and reversible enough to permit the dissociation of molecules in response to changes in the solution’s pH. When compared to other protein A-based approaches, this one has been shown to be more advantageous than its counterparts in terms of specificity, ease of use, and cost-effectiveness. Information on polymeric, macroporous, monolithic adsorbents used in the affinity chromatographic purification of lectins has been published and explored.

Influence of the milling materials on the mechanochemical synthesis of magnetic iron oxide nanoparticles

The aim of this work is to synthesize iron oxide nanoparticles (IONPs) by a mechanochemical process using a high-energy planetary ball mill, with two types of vials and balls (stainless-steel and zirconia) and two reactive mixtures. This preparative route is simple, scalable and environmentally friendly. The influence of milling materials on the structural and magnetic properties of the obtained IONPs was studied. Composition, crystalline structure, morphology and magnetic properties of the IONPs were analyzed by XRD, Raman spectroscopy, SEM, TEM and VSM techniques. An iron oxide with spinel structure, compatible with magnetite (Fe3O4) or maghemite (γ-Fe2O3), was formed in the prepared samples, when using FeCl3 or FeCl3/Fe with stainless steel vials, or FeCl3/Fe with zirconia vials. The results indicate that the formation of spinel magnetic phases is strongly influenced by the presence of metallic Fe in the starting mixture as well as the nature of the container, which can (or cannot) supply Fe during the milling. The obtained results are presented with a perspective oriented to the biomedical application of the IONPs, considering mean particle sizes, magnetic properties, and chemical stability in simulated body fluids.

Bio-diesel synthesis from waste sunflower oil: Experimental and multilayer perceptron neural network modeling

Transesterification being the most widely utilized way for biodiesel synthesis, the present work focuses on a single-step transesterification reaction between second-used sunflower oil and methanol as a reactant mixture with potassium hydroxide as a base catalyst. The parameter study exhibits encouraging results in terms of biodiesel/ ester conversion of the second used sunflower oil. Optimum parameters like temperature (62.3 °C), the molar ratio of methanol/ oil (1:5), and potassium hydroxide (2.85 wt%) were estimated for maximum biodiesel conversion (97.06 %). An artificial intelligence (AI) based formalism known as multilayer perceptron neural network (MLPNN) is utilized to develop the prediction model for biodiesel conversion (ml) (y0). The input space of the MLPNN-based model comprises of four operating parameters, viz. temperature (oC), second used sunflower oil (ml), methanol (ml), and reaction time (min). The proposed model is trained with the error-back propagation methodology. The high correlation coefficient (CCTraining=0.978;CCTest=0.999) and low root mean square error (RMSETraining=80.392;RMSETest=27.891) values indicate the excellent accuracy of prediction and generalization of the developed model. As a result, the proposed model can be conveniently engaged for further designing of biodiesel synthesis experimentation.

Control Over the Reactivity of Aggregates and Mineral Additives in Portland Cement Compositions by Electron Beam and Heat Treatment

The effect of electron-beam treatment (EBT) and heat treatment (HT) of silica-based aggregates and mineral additives in Portland cement mortars on the intensity of alkali-silica reactions (ASRs) with their participation, which are dangerous for concrete structures, is studied. It is established that heating to a temperature of 900°C and the EBT of sand free of alkali-reactive inclusions, leads to a significant increase in the reactivity of cement-sand mortar mixtures, which increases with an increase in the absorbed dose and a corresponding increase in the content of acid hydroxyl groups on the sand surface. In the case of sand containing reactive inclusions of chalcedony, EBT leads to an increase in reactivity, and HT, to a decrease. Treatment of microsilica and metakaolin mineral additives capable of ASR inhibition leads to an increase in their inhibitory effect. The results obtained are promising for modeling the expansion of concrete as a result of ASR and increasing their resistance to fracture in alkaline media.

Plasma-assisted deflagration to detonation transition in a microchannel with fast-frame imaging and hybrid fs/ps coherent anti-Stokes Raman scattering measurements

This study examines kinetic enhancement by nanosecond dielectric barrier discharge (ns-DBD) plasma on fuel-lean, Φ = 0.7, dimethyl ether (DME), oxygen (O2), and argon (Ar) premixture during deflagration to detonation transition (DDT) experiments in a microchannel. Nonequilibrium plasma produces active species and radicals as well as fast and slow heating of a mixture to promote ignition due to energetic electrons, ions, and electronic and vibrational excitations. Experiments are conducted to examine the influence of the plasma discharge on the premixture and on the resultant deflagration to detonation transition (DDT) onset time and distance through the use of high-speed imaging and one-dimensional, two-beam, femtosecond/picosecond, coherent anti-Stokes Raman scattering (CARS). A high-speed camera is used to trace the time histories of flame front position and velocity and to identify the dynamics and onset of DDT. The results show that plasma discharge can nonlinearly affect the onset time and distance of DDT. It is shown that a small number of plasma discharge pulses prior to ignition result in reduced DDT onset time and distance by 60% and 40%, respectively, when compared to the results without pre-excitation by ns discharges. The results also show that an increase of number of the plasma discharge pulses results in an extended DDT onset time and distance of 224% and 94%, respectively. Time history of the deflagration wave speed of DME and the analysis of ignition timescale under the choking condition of the burned gas of the deflagration wave suggest low temperature ignition may play a role for DME near the isobaric choking condition of the burned gas and the DDT. Plasma-induced low temperature oxidation of the reactive mixture is assessed via the CO2 to O2 ratio as measured through fs/ps CARS during the gas excitation in discharges. CARS measurements also confirm negligible vibrational and rotational heating of the gas by discharge. The present experiments demonstrate the ability of nonequilibrium plasma to alter the chemistry of DME/O2/Ar premixtures in order to control DDT for applications in advanced propulsion engines.