Experimental Model For Study Research Articles

Kinetic modeling of CO assisted passive NOx adsorption on Pd/SSZ-13

Passive NOx adsorption (PNA) has been recently developed as a promising technology for controlling the NOx emissions during the cold start period. In this work, we illustrate a CO-assisted mechanism by combining experimental and kinetic modeling studies. Pd/SSZ-13 has been synthesized, characterized and evaluated as a PNA in low-temperature NOx adsorption and temperature program desorption cycles, to represent multiple cold start periods. The gas compositions were also systemically changed, where both the effect of varying NOx and CO feed was evaluated in the presence of high water and oxygen contents. A kinetic model was developed to simulate the profiles of NO and NO2, including three initial Pd sites (Z-Pd(II)Z-, Z-[Pd(II)OH]+ and PdO). It is concluded from XPS and in situ DRIFTS experiments, flow reactor measurements and modelling observations that CO reduces Pd(II) species to Pd(I)/Pd(0) species, which increases the stability of the stored NOx species, resulting in a release above the urea dosing temperature. The model could well describe the experimental features, including the effect of CO. In addition, the model was used for full-scale catalytic converter simulations.

Theoretical and Experimental Study of a Thermo-Mechanical Model of a Shape Memory Alloy Actuator Considering Minor Hystereses

The paper presents a theoretical and experimental investigation of a thermo-mechanical model of an actuator composed of a shape memory alloy wire arranged in series with a bias spring. The developed mathematical model considers the dynamics of the actuator in the thermal and mechanical domains. The modelling accuracy is increased through the developed algorithm for modelling the minor and sub minor hystereses, thus removing the disadvantages of the classical model. The algorithm improves the accuracy, especially when using pulse-width modulation control, for which minor and sub minor hystereses are likely to occur. Experimental studies show that the system is very sensitive, and there are physical factors whose presence cannot be considered in the mathematical model. The experimental research has shown that setting constant values of the duty cycle is impossible to obtain a stable value of displacement and force. The comparison between the developed mathematical model results and the experimental results shows that the differences are acceptable. The improved modelling serves as a basis for designing such actuators and creating an improved automatic feedback control system to maintain a given displacement (force) or trajectory tracking.

Targeting Inflammatory Cytokines to Improve Type 2 Diabetes Control.

Type 2 diabetes (T2D) is one of the most common chronic metabolic disorders in adulthood worldwide, whose pathophysiology includes an abnormal immune response accompanied by cytokine dysregulation and inflammation. As the T2D-related inflammation and its progression were associated with the balance between pro and anti-inflammatory cytokines, anticytokine treatments might represent an additional therapeutic option for T2D patients. This review focuses on existing evidence for antihyperglycemic properties of disease-modifying antirheumatic drugs (DMARDs) and anticytokine agents (anti-TNF-α, anti-interleukin-(IL-) 6, -IL-1, -IL-17, -IL-23, etc.). Emphasis is placed on their molecular mechanisms and on the biological rationale for clinical use. Finally, we briefly summarize the results from experimental model studies and promising clinical trials about the potential of anticytokine therapies in T2D, discussing the effects of these drugs on systemic and islet inflammation, beta-cell function, insulin secretion, and insulin sensitivity.

An Experimental Study of Picture Word Inductive Model to Foster Students’ Vocabulary in an Indonesian Junior Highschool Setting

The objective of the research is to know whether the aplication of Picture word inductive model improve students’ vocabulary at SMP Negeri 2 Jikumerasa. In this research, the researcher used quantitative research method with pre-Experimental design of the one group pretest and posttest. The sample of the research was 26 students learning at the seventh grade of SMP Negeri 2 Jikumerasa which consist of 7 male students and 19 female students. The data were collected by using 30 items of multiple choices test. The data obtained were analyzed by applying dependent t-test the formula. The result of the analysis show that the average score in posttest X2 = 1818 is greater than score of pretest X1 = 1449, calculation of t-test = 9.39 exceeds the t-table = 1.711 at significant level of = 0.05. Thus the alternative hypothesis (Hα) stating that the use of Picture word inductive model improve students English vocabulary is accepted and the null hypothesis (H0) stating that the Picture Word Inductive Model can not improve students‟ English vocabulary is rejected.

Kallistatin limits abdominal aortic aneurysm by attenuating generation of reactive oxygen species and apoptosis

Inflammation, vascular smooth muscle cell apoptosis and oxidative stress are believed to play important roles in abdominal aortic aneurysm (AAA) pathogenesis. Human kallistatin (KAL; gene SERPINA4) is a serine proteinase inhibitor previously shown to inhibit inflammation, apoptosis and oxidative stress. The aim of this study was to investigate the role of KAL in AAA through studies in experimental mouse models and patients. Serum KAL concentration was negatively associated with the diagnosis and growth of human AAA. Transgenic overexpression of the human KAL gene (KS-Tg) or administration of recombinant human KAL (rhKAL) inhibited AAA in the calcium phosphate (CaPO4) and subcutaneous angiotensin II (AngII) infusion mouse models. Upregulation of KAL in both models resulted in reduction in the severity of aortic elastin degradation, reduced markers of oxidative stress and less vascular smooth muscle apoptosis within the aorta. Administration of rhKAL to vascular smooth muscle cells incubated in the presence of AngII or in human AAA thrombus-conditioned media reduced apoptosis and downregulated markers of oxidative stress. These effects of KAL were associated with upregulation of Sirtuin 1 activity within the aortas of both KS-Tg mice and rodents receiving rhKAL. These results suggest KAL-Sirtuin 1 signalling limits aortic wall remodelling and aneurysm development through reductions in oxidative stress and vascular smooth muscle cell apoptosis. Upregulating KAL may be a novel therapeutic strategy for AAA.

Experimental and theoretical model study on the dynamic mechanical behavior of sintered NdFeB

Sintered neodymium iron boron (NdFeB) is a widely applied permanent magnet, whose dynamic mechanical properties restrict the further development of its application. In order to provide a theoretical basis for the application of NdFeB in the shock field, the dynamic mechanical behavior of sintered NdFeB was studied experimentally and theoretically in this paper. First, the Split Hopkinson Pressure Bar (SHPB) experiments under different strain rates were carried out. The dynamic process was captured by a high-speed camera, and the strain data measured by oscilloscope was processed with the three-wave method. Combined with the electron microscope analysis of the recovered samples, the dynamic failure process and characteristics of NdFeB under high-speed impact were explored, which provided an experimental basis for the following theoretical research. Given the theoretical deficiency of the dynamic mechanical properties of sintered NdFeB and the assumption of microcracks with uniform distribution and no friction, a theoretical model of damage evolution process of brittle materials was established based on the dynamic crack growth criterion. Combining the damage evolution model with Zhu-Wang-Tang (ZWT) constitutive model, the damage constitutive model of sintered NdFeB was established, whose validity was verified by the comparison with the experimental data.

Comparison between normal and reverse orientation of graft in functional and histomorphological outcomes after autologous nerve grafting: An experimental study in the mouse model.

Autologous nerve grafting has been considered the gold standard for the treatment of irreparable nerve gaps. However, the choice of effective proximodistal orientation of autografts (normal or reversed) is controversial. Therefore, we compared functional and histological outcomes between normal and reversed orientations of autografts in a mouse sciatic nerve model. Thirty C57BL/6J mice weighing 20-25 g were assigned to the donor, normally oriented autograft, and reverse-oriented autograft groups (n= 10 per group). A 10-mm section of the sciatic nerve was harvested from a donor mouse. Half the harvested nerve was grafted onto an irreparable gap in a recipient mouse using either a normal or reversed orientation. The sciatic functional index (SFI) was measured biweekly for up to 12 weeks postoperatively. Morphological analysis was performed using immunofluorescence staining for neurofilament (NF) and myelin protein zero (P0) in cross-sectional and whole-mount nerve preparations in 12 weeks postoperatively. Additionally, morphological analysis of the tibialis anterior muscle was performed using hematoxylin and eosin staining. NF or P0-expressing axons were counted and cross-sectional area (CSA) and minimum Feret's diameter of myofibers were measured. The SFI recovered gradually up to 12 weeks after autografting, but there were no significant differences in the SFI between the normal and reversed orientations. The number of NF-expressing axons in center of graft was significantly higher in the normal orientation than in the reversed orientation (P < .05). However, there were no significant differences in the number and mean intensity of P0-expressing axons between the orientations. The CSA of myofibers was significantly larger in the normal orientation than in the reversed orientation (P < .05). Normally oriented autografts promote axonal regrowth and prevent neurogenic muscular atrophy compared with reverse-oriented autografts. However, despite these positive histomorphometric effects, the proximodistal orientation of the autograft does not affect functional outcomes.

Long Term Effects of Streptozotocin Induced Diabetes Mellitus on Hepatic, Nephrotic and Cardiac Physiology of Female Wistar Rats

Background: Diabetes mellitus is a metabolic disorder which leads to complications that affect the heart, kidney, liver and other vital organs. Most reports on diabetes have focused on diabetes induction using male rat models in short term studies.Objective: Here, we described the induction of diabetes in female rat and the complications of diabetes following long term hyperglycemia in female Wistar rats.Method: Rats were assigned into two groups: control (n=10) and diabetic (n=10). The latter was administered a single (50mg/Kg body weight) intraperitoneal injection of streptozotocin. Bodyweight and blood glucose were assessed for 14 weeks, after which the animals were sacrificed and biochemical and morphology parameters of the liver, kidney and heart were determined.Results: Diabetic rats showed continuous emaciation post STZ induction. The glycated haemoglobin, protein level, lipid profile, liver and kidney function markers were significantly different (p&lt;0.05) from the control. Catalase, superoxide dismutase and glutathione-s-transferase activities were also significantly reduced in the heart, liver and kidney, and a concomitant increase in malondialdehyde concentration was observed. Focal tubular necrosis, pulmonary congestion and mild hyperplasia of kupffer cells were observed in the tissues and all tissues showed negative CD79a expression.Conclusion: This study provides data that could be useful for modelling long-term diabetes mellitus studies in female experimental rat models.

Dentin Growth after Direct Pulp Capping with the Different Fractions of Plasma Rich in Growth Factors (PRGF) vs. MTA: Experimental Study in Animal Model

Background: This study aimed to evaluate the area of dentin growth in rabbit incisors after pulp capping with plasma rich in growth factors (PRGF) compared with mineral trioxide aggregate (MTA) by fluorescence. Methods: twenty-seven upper and lower incisors of rabbits were divided into 4 groups: poor PRGF (F1) (n = 9 teeth), rich PRGF (F2) (n = 8 teeth), ProRoot MTA (positive control, n = 5 teeth), and untreated (NC) (negative control, n = 5). Fluorochrome markers were injected 24 h before surgery and the day before euthanasia, 28 days after the vital pulp therapy (VPT). Two transverse cuts were performed to every tooth: the first cut (A), 1 mm incisal to the gingival margin, and the second cut (B), 5 mm apical to the first cut. The sections were assessed with histomorphometric evaluation by fluorescence microscopy, comparing the dentin area between fluorescence marks and the total mineralized area. Results: The higher percentage of dentin growth was observed in the F2 group (B = 63.25%, A = 36.52%), followed by F1 (B = 57.63%, A = 30,12%) and MTA (B = 38.64%, A = 15.74%). The group with lowest percentage of dentin growth was the NC group (B = 29.22%, A = 7.82%). Significant difference (p < 0.05) was found between F2 group and MTA, also statistically significant difference has been observed comparing dentin growth areas of NC group with F1 and F2 groups. Conclusions: The application of PRGF rich and poor fraction as a pulp capping material stimulated dentin formation more intensively than MTA and NC.

Alpha-ketoglutarate ameliorates pressure overload-induced chronic cardiac dysfunction in mice

Increasing evidence indicates the involvement of myocardial oxidative injury and mitochondrial dysfunction in the pathophysiology of heart failure (HF). Alpha-ketoglutarate (AKG) is an intermediate metabolite of the tricarboxylic acid (TCA) cycle that participates in different cellular metabolic and regulatory pathways. The circulating concentration of AKG was found to decrease with ageing and is elevated after acute exercise and resistance exercise and in HF. Recent studies in experimental models have shown that dietary AKG reduces reactive oxygen species (ROS) production and systemic inflammatory cytokine levels, regulates metabolism, extends lifespan and delays the occurrence of age-related decline. However, the effects of AKG on HF remain unclear. In the present study, we explored the effects of AKG on left ventricular (LV) systolic function, the myocardial ROS content and mitophagy in mice with transverse aortic constriction (TAC). AKG supplementation inhibited pressure overload-induced myocardial hypertrophy and fibrosis and improved cardiac systolic dysfunction; in vitro, AKG decreased the Ang II-induced upregulation of β-MHC and ANP, reduced ROS production and cardiomyocyte apoptosis, and repaired Ang II-mediated injury to the mitochondrial membrane potential (MMP). These benefits of AKG in the TAC mice may have been obtained by enhanced mitophagy, which cleared damaged mitochondria. In summary, our study suggests that AKG improves myocardial hypertrophy remodelling, fibrosis and LV systolic dysfunction in the pressure-overloaded heart by promoting mitophagy to clear damaged mitochondria and reduce ROS production; thus, AKG may have therapeutic potential for HF.

Confined dipole and exchange spin waves in a bulk chiral magnet with Dzyaloshinskii-Moriya interaction

The Dzyaloshinskii-Moriya interaction (DMI) has an impact on excited spin waves in the chiral magnet Cu$_2$OSeO$_3$ by means of introducing asymmetry on their dispersion relations. The confined eigenmodes of a chiral magnet are hence no longer the conventional standing spin waves. Here we report a combined experimental and micromagnetic modeling study by broadband microwave spectroscopy we observe confined spin waves up to eleventh order in bulk Cu$_2$OSeO$_3$ in the field-polarized state. In micromagnetic simulations we find similarly rich spectra. They indicate the simultaneous excitation of both dipole- and exchange-dominated spin waves with wavelengths down to (47.2 $\pm$ 0.05) nm attributed to the exchange interaction modulation. Our results suggest DMI to be effective to create exchange spin waves in a bulk sample without the challenging nanofabrication and thereby to explore their scattering with noncollinear spin textures.

An experimental and detailed kinetic modeling study of the pyrolysis and oxidation of allene and propyne over a wide range of conditions

Allene and propyne are important intermediates in the pyrolysis and oxidation of higher hydrocarbon fuels, and they are also a major source of propargyl radical formation, which can recombine into different C6H6 isomers and finally produce soot. In a prior work (Panigrahy et al., “A comprehensive experimental and improved kinetic modeling study on the pyrolysis and oxidation of propyne”, Proc. Combust. Inst 38 (2021)), the pyrolysis, ignition , and laminar flame speed of propyne were investigated. To understand the kinetic features of initial fuel breakdown and oxidation of the two C3H4 isomers, new measurements for allene pyrolysis and oxidation are conducted in the present paper at the same operating conditions as those studied previously for propyne. Ignition delay times of allene are measured using a high-pressure shock tube and a heated twin-opposed piston rapid compression machine in the temperature range 690–1450 K at equivalence ratios of 0.5, 1.0 and 2.0 in ‘air’, and at pressures of 10 and 30 bar. Pyrolysis species measurements of allene and propyne are also performed using a gas chromatography integrated single-pulse shock tube in the temperature range 1000–1700 K at pressure of 2 and 5 bar. Furthermore, laminar flame speeds of allene are measured at elevated gas temperatures of 373 K at pressures of 1 and 2 bar for a wide range of equivalence ratios from 0.6 to 1.5. A newly updated kinetic mechanism developed for this study is the first model that can well reproduce all of the experimental results for both allene and propyne. It is observed that in the pyrolysis process, allene dissociates faster than propyne. Both isomers exhibit similar ignition delay times at high temperatures (>1000 K), while, at intermediate temperatures (770–1000 K) propyne is the faster to ignite, and at lower temperatures (< 770 K) allene becomes more reactive. Furthermore, laminar flame speeds for propyne are found to be slightly faster than those for allene under the conditions studied in this work.

Experimental and kinetic modeling study on NH3/syngas/air and NH3/bio-syngas/air premixed laminar flames at elevated temperature

Ammonia (NH3) can help achieve large-scale storage and long-distance transportation of renewable energy. The co-firing of NH3 with syngas and bio-syngas and increasing the initial temperature of reactants are economical and effective methods to enhance the reactivity of NH3 flames in boilers and gas turbines. An accurate kinetic model is essential for developing corresponding burners. The current kinetic models are not accurate enough in temperature dependence. Laminar burning velocities (SL) of NH3/syngas/air and NH3/bio-syngas/air mixtures were measured at various H2 contents in syngas and NH3 contents in the mixtures, equivalence ratios of 0.7~1.4, atmospheric pressure, and elevated temperature up to 423 K in a high-pressure constant-volume combustion vessel. A detailed kinetic model was developed for NH3/syngas combustion and validated based on the literature data. The experimental results show that slightly rich flame, high mole fractions of syngas/bio-syngas, and elevated initial temperature contribute to increasing the SL. Kinetic modeling analysis was performed for interpreting the effect of fuel composition, equivalence ratio and initial temperature on the laminar flame propagation characteristics. The elevated H2 content in syngas provides a stronger chemical effect and the enhanced laminar flame propagation of NH3/syngas/air and NH3/bio-syngas/air mixtures is dominated by chemical effect. Due to the presence of diluent (CO2 and N2), thermal effect has a negative influence on the enhancement of NH3/bio-syngas/air flame propagation. Although diluent hardly changes the NH3 consumption pathways, it will significantly reduce the NH3 consumption. Different NH3 consumption pathways are preferred by lean and rich flame. Sensitivity analysis shows that NH2 chemistry is favored by rich flames. Since NH2 + NH = N2H2 + H promotes the production of H radical in rich flames, it has the greatest influence on the SL of rich flames. H2 is more capable of improving the temperature dependence of NH3/syngas/air flame than CO. The increased importance of NH3 chemistry accounts for the strong temperature dependence of NH3/bio-syngas/air flame.

An experimental modelling and performance validation study: Top gas pressure tracking system in a blast furnace using soft computing methods

The blast furnace is a master iron-producing plant of iron and steel factories and affected by several process parameters as well as top gas pressure , which is a key process control phenomenon to maintain stability and operational productivity in such plants. Blast furnace operation is not tolerant to any interruption, unbalanced operations, momentary disturbances or loss of control due to its nature of intensive chemical reactions and heat balance requirements. Consequently, it is crucial to monitor and control top gas system components of the furnace with instrumentation measurements to maintain stable, efficient operation and system safety ongoing. In this study, a novel top gas pressure tracking system is developed using the chronologically obtained live process data of Erdemir BF#2 in Turkey. Eight process parameters are considered as input parameters as per the plant maintenance team's recommendations and soft computing methods, artificial neural networks and adaptive neuro fuzzy inference system are employed and a statistical regression tool, autoregressive integrated moving average, is also applied for comparison. Performance and success ratio analysis is carried out using coefficient of determination ( R2), mean absolute percentage error and root mean squared error terms. The best performing model output for the adaptive neuro fuzzy inference system is found to be 0.95, 1.21 and 0.023, and slightly lower performance is obtained for the artificial neural network model with the output values of 0.94, 0.029 and 1.32 against R2, mean absolute percentage error and root mean squared error terms, respectively. The maximum prediction error is found to be 9.85% and 10.2%, and the average prediction error is found to be 1.19% and 1.29% for adaptive neuro fuzzy inference system and ANN models, respectively, for optimum simulations. The proposed neuro-fuzzy-driven top gas pressure prediction system is unique in the literature and should be integrated into existing control systems to improve operational awareness and sustainability or can be used as input guidance for a possible future top gas recovery system.

Experimental and Mesoscopic Modeling Study of Water/Crude Oil Interfacial Tension

Experimental and Mesoscopic Modeling Study of Water/Crude Oil Interfacial Tension

Performance Indicators for Benchmarking Solar Thermochemical Fuel Processes and Reactors

Concentrated solar energy offers a source for renewable high-temperature process heat that can be used to efficiently drive endothermic chemical processes, converting the entire spectrum of solar radiation into chemical energy. In particular, solar-driven thermochemical processes for the production of fuels include reforming of methane and other hydrocarbons, gasification of biomass, coal, and other carbonaceous feedstock, and metal oxide redox cycles for splitting H2O and CO2. A notable issue in the development of these processes and their associated solar reactors is the lack of consistent reporting methods for experimental demonstrations and modelling studies, which complicates the benchmarking of the corresponding technologies. In this work we formulate dimensionless performance indicators based on mass and energy balances of such reacting systems, namely: energy efficiency, conversion extent, selectivity, and yield. Examples are outlined for the generic processes mention above. We then provide guidelines for reporting on such processes and reactors and suggest performance benchmarking on four key criteria: energy efficiency, conversion extent, product selectivity, and performance stability.

Effects of 2-Butanol Addition on Waste Cooking Oil Biodiesel Density: An Updated Experimental Measurement and Thermodynamic Modeling Study

Biodiesels will become the most popular alternative energy resource to fossil diesels; they can be used alone or blended with an oxygenated additive in any proportion. The properties of biodiesels strongly depend on the type of the fatty acid methyl esters (FAME) that compose them. The main objective of the present work is to investigate the influence of 2-butanol addition on the waste cooking oil biodiesel (WCOB), for this fact, the new experimental density data (952 points) of WCOB + 2-butanol binary mixtures over a wide range of composition [seven compositions; 0 ≤ (WCOB) mole fraction x ≤ 1] between 0.1 and 140 MPa and 298.15 and 393.15 K are presented. The experimental data were correlated using Tait and perturbed chain-statistical associating fluid theory (PC-SAFT) equations of state (EoS), to our knowledge, this is the first time that density measurements for the WCOB + 2-butanol mixture are correlated using the famous PC-SAFT EoS. The Tait equation predicts successfully the density with a global absolute average deviation (AAD) of 0.089%, while the PC-SAFT model correlates well the density with a very small global AAD of 0.223% in each composition. Furthermore, contrary to the Tait equation, the PC-SAFT model can explain some interactions between fluid molecules. From the experimental data, the excess volumes VE have been calculated and fitted using the Redlich-Kister equation with a very small global standard deviation of 7.49 × 10-5 cm3 mol-1, and VE show a positive and symmetric parabolic shape in all composition ranges. Finally, the isobaric thermal expansivity, αp, and the isothermal compressibility, κT, have been derived from the Tait equation and their observed trend was as expected.

What Is the Potential Role of Poly(ADP-Ribose) Polymerase 1 in Parkinson Disease?

Poly(ADP-ribose) (PAR) polymerase 1 (PARP-1) is an enzyme primarily activated in response to DNA damage and modifies proteins by a process known as PARylation. PARP-1 has a major role in DNA damage repair and participates in several cellular processes, including regulation of chromatin structure, transcriptional machinery, RNA processing, and energy metabolism 1-3 PARP-1 participates in a nuclear–mitochondrial crosstalk that is critical for the maintenance of mitochondrial health.4,5 Studies in experimental models indicate that PARP-1 overactivation is associated with cell death in neurologic disorders due to ischemia, neuroinflammation, and neurodegeneration.5-11 PARP-1 overactivation triggers a unique form of programmed cell death known as parthanatos (PARP-1–dependent cell death). One neurodegenerative disorder associated with PARP-1 overactivation is Parkinson disease (PD). A pivotal study showed that recombinant α-synuclein (α-Syn) fibrils promote neuronal death both in vitro and in vivo via activation of PARP-1, and that PARylation accelerates α-Syn fibrillization converting α-Syn fibrils to a more toxic strain, thus establishing a feedforward pathogenic loop.12 There is evidence of PARP-1 activation in the substantia nigra, which may contribute to the pathogenesis of PD and constitute a therapeutic target for disease modification.10,13 This is potentially relevant as PARP-1 inhibitors are currently being used clinically as synergizing agents in the treatment of cancer.3,14 There are comprehensive reviews on the role of PARP-1 in disease.8-11,15 A brief review of the effects of PARP-1 functions may thus be relevant to neurologists (see the figure).

A comprehensive experimental and kinetic modeling study of dimethoxymethane combustion

Dimethoxymethane (DMM, CH3OCH2OCH3), the simplest member in the class of polyoxymethylene dimethyl ethers (PODE), is regarded as a promising fuel substitute for compression ignition engines. To better understand its combustion characteristics, a comprehensive experimental and kinetic modeling study on the combustion of DMM was conducted. Ignition delay times (IDTs) of DMM/O2/Ar mixtures were measured in a shock tube at pressures from 1.0 to 10 atm, for temperatures from 1050 to 1450 K, and equivalence ratios of 0.5, 1.0 and 2.0. A predominantly ab initio derived detailed kinetic model of DMM with 121 species and 646 reactions was developed based on AramcoMech2.0 with an updated sub-mechanism of methyl formate (MF, CH3OCHO). CO bond fissions occurred in CH2O and CH3O moieties were demonstrated to be the dominating reaction pathways in DMM high temperature chemistry rather than the competing non-radical decomposition channels. Flux and sensitivity analyses indicated that the two CO bond fissions have a comparatively promoting effect on reactivity, while the DMM = CH3OCH2O + CH3 reaction was the dominating channel at high temperatures. The proposed model was also validated against literature experimental data, including ignition delay times, jet stirred reactor species concentrations, laminar pre-mixed flame speciation, laminar burning velocities and plug-flow reactor speciation. The good performance of the proposed model for reproducing these data revealed its ability to predict DMM combustion over a wide range of conditions. Major reaction pathways of DMM could also apply to larger PODE compounds.

Experimental and kinetic modeling studies of the low-temperature oxidation of 2-methylfuran in a jet-stirred reactor

2-Methylfuran (MF), a promising biofuel, produced from non-edible biomass, is desirable as an alternative fuel or fuel additive to internal combustion engines. For a better understanding of the ignition process in engines, the low-temperature oxidation experiments of MF at the temperature range of 600 – 925 K and atmospheric pressure with different equivalence ratios (0.5, 1.0, and 2.0), were performed in a jet-stirred reactor. Synchrotron vacuum ultraviolet photoionization mass spectrometry was used to identify and measure the intermediates and products in the oxidation process, especially for the isomers (furfural/2-ethylfuran and furan/vinyl ketene), species with identical mass-to-charge ratio (methanol/oxygen and aldehyde/carbon dioxide), and the other oxygenated and hydrocarbon products. The typical negative-temperature-coefficient behavior was not observed in the low-temperature oxidation of MF. The dominant consumption pathways of MF in low-temperature oxidation are the hydroxyl radical/hydrogen atom-addition reactions on the ring and hydrogen atom-abstraction reactions on the side methyl group by hydroxyl radical/hydroperoxyl radical/hydrogen atom, while the contribution of unimolecular decomposition reactions is almost negligible. 2-Furylmethyl radical is a key intermediate in the low-temperature oxidation of MF. Furfural and 2-ethylfuran, as the subsequent products from 2-furylmethyl low-temperature oxidation, were identified as the early-stage products. Besides, the important chemistry of other important species, especially acrolein and methyl vinyl ketone, were also discussed at different equivalence ratios.