Tube Reactor Research Articles

Monitoring functional immune responses with a cytokine release assay: ISS flight hardware design and experimental protocol for whole blood cultures executed under microgravity conditions.

Introduction: Long-term space missions trigger a prolonged neuroendocrine stress response leading to immune system dysregulation evidenced by susceptibility to infections, viral reactivation, and skin irritations. However, due to existing technical constraints, real-time functional immune assessments are not currently available to crew inflight. The in vitro cytokine release assay (CRA) has been effectively employed to study the stimulated cytokine response of immune cells in whole blood albeit limited to pre- and post-flight sessions. A novel two-valve reaction tube (RT) has been developed to enable the execution of the CRA on the International Space Station (ISS). Methods: In a comprehensive test campaign, we assessed the suitability of three materials (silicone, C-Flex, and PVC) for the RT design in terms of biochemical compatibility, chemical stability, and final data quality analysis. Furthermore, we thoroughly examined additional quality criteria such as safety, handling, and the frozen storage of antigens within the RTs. The validation of the proposed crew procedure was conducted during a parabolic flight campaign. Results: The selected material and procedure proved to be both feasible and secure yielding consistent and dependable data outcomes. This new hardware allows for the stimulation of blood samples on board the ISS, with subsequent analysis still conducted on the ground. Discussion: The resultant data promises to offer a more accurate understanding of the stress-induced neuroendocrine modulation of immunity during space travel providing valuable insights for the scientific community. Furthermore, the versatile nature of the RT suggests its potential utility as a testing platform for various other assays or sample types.

Rapid Detection of the Strawberry Foliar Nematode Aphelenchoides fragariae Using Recombinase Polymerase Amplification Assay with Lateral Flow Dipsticks.

Rapid and reliable diagnostic methods for plant-parasitic nematodes are critical for facilitating the selection of effective control measures. A diagnostic recombinase polymerase amplification (RPA) assay for Aphelenchoides fragariae using a TwistAmp® Basic Kit (TwistDx, Cambridge, UK) and AmplifyRP® Acceler8® Discovery Kit (Agdia, Elkhart, IN, USA) combined with lateral flow dipsticks (LF) has been developed. In this study, a LF-RPA assay was designed that targets the ITS rRNA gene of A. fragariae. This assay enables the specific detection of A. fragariae from crude nematode extracts without a DNA extraction step, and from DNA extracts of plant tissues infected with this nematode species. The LF-RPA assay showed reliable detection within 18-25 min with a sensitivity of 0.03 nematode per reaction tube for crude nematode extracts or 0.3 nematode per reaction tube using plant DNA extracts from 0.1 g of fresh leaves. The LF-RPA assay was developed and validated with a wide range of nematode and plant samples. Aphelenchoides fragariae was identified from seed samples in California. The LF-RPA assay has great potential for nematode diagnostics in the laboratory with minimal available equipment.

Development of triplex assay for simultaneous detection of Escherichia coli, methicillin resistant and sensitive Staphylococcus aureus in raw pork samples of retail markets.

Escherichia coli and Staphylococcus aureus are the most important food borne pathogen transmitting from animal meat and meat products. Therefore, it is vital to design an accurate and specific diagnostic tool for identifying those food-borne pathogens in animal meat and meat products. In the current study, E. coli, methicillin-resistant and sensitive S. aureus (MRSA and MSSA) were simultaneously detected using a developed triplex PCR-based technique. To obtain an optimal reaction parameter, the multiplex assay was optimised by changing just one parameter while holding the others constant. Specificity of the assay was assessed using several porcine bacterial template DNA. The plasmid DNA was used to test the multiplex PCR assay's sensitivity and interference in spiked pork samples. E. coli, MRSA, and MSSA each have PCR amplified products with sizes of 335, 533, and 209bp, respectively. The assay detects a minimum microbial load of 102CFU/μl for all the three pathogens and can identify bacterial DNA as low as 10-2ng/µl. The assay was validated employing 210 pork samples obtained from retail meat shops and slaughter houses, with MRSA, E. coli, and MSSA with the occurrence rate of 1.9%, 42.38%, and 18.1%, respectively. The rate of mixed bacterial contamination in pork meat samples examined with the developed method was 6.19%, 1.43%, 1.90%, and 1.43% for MSSA & E. coli, MRSA & E. coli, MSSA & MRSA, and E. coli, MSSA & MRSA, respectively. The developed multiplex PCR assay is quick and efficient, and it can distinguish between different bacterial pathogens in a single reaction tube.

Measuring the refraction index of luminescent carbon nanodots forming Gaussian beam using the tracker software

Nanotechnology is currently regarded as one of the fastest-growing technologies. Equipping students with some understanding of nanotechnology in relation to physics ideas may trigger their interest and inspire them to learn physics. This study is aimed to measure the refraction index of Cdots solution using the Gaussian beam and Tracker software. The method used in this research is quantitative descriptive method with the stages of research that include designing, construction, developing, and testing the measuring instrument. The procedure in this study begins by preparing the Cdots solution from cajuput oil (CJO) distillation wastes. The Cdots are then characterized using the UV-visible (UV-Vis), photoluminescence (PL), time resolved-PL (TRPL), and Fourier transform infrared (FTIR) spectroscopies. The Cdots solution is then put into a reaction tube with solution height variation. The violet/UV laser pointer is exposed upward towards the Cdots solution from the bottom of the reaction tube producing a Gaussian beam inside the reaction tube. The Gaussian beam is then photographed, which then the format is converted into a video format. The video format of the Gaussian beam is analyzed using the Tracker software. The characterizations of the Cdots show i) an absorption peak at a wavelength of 216.0 nm, ii) an emission peak at 512.29 nm indicating cyan luminescence, iii) an electronic lifetime of 51.3 ns, and iii) functional groups of O-H; C=C; and C=O. Moreover, the Gaussian beams are formed for various heights of the Cdots solution, i.e.: from 5.364 cm to 13.000 cm. Using the Tracker software, the value of the Cdots’ refraction index is 1.29 0.03, which is comparable to the refraction index of water. This measuring instrument has the potential to be used in high school physics classes and/or first-year university physics courses.

A microfluidic-based quantitative analysis system for the multiplexed genetic diagnosis of human viral infections using colorimetric loop-mediated isothermal amplification.

In this study, a microfluidic-based system utilizing colorimetric loop-mediated isothermal amplification (LAMP) is introduced for the quantitative analysis of nucleic acid targets. This system offers a user-friendly and cost-effective platform for the multiplexed genetic diagnosis of various infectious diseases across multiple samples. It includes time-lapse imaging equipment for capturing images of the microfluidic device during the LAMP assay and a hue-based quantitative analysis software to analyze the LAMP reaction, streamlining diagnostic procedures. An electric pipette was used to simplify the loading of samples and LAMP reagents into the device, allowing easy operation even by untrained individuals. The hue-based analysis software employs efficient image processing and post-processing techniques to calculate DNA amplification curves based on color changes in multiple reaction chambers. This software automates several tasks, such as identifying reaction chamber areas from time-lapse images, quantifying color information within each chamber, correcting baselines of DNA amplification curves, fitting experimental data to theoretical curves, and determining the threshold time for each curve. To validate the developed system, conventional off-chip LAMP assays were conducted with a 25 μL reaction mixture in 0.2 mL polymerase chain reaction (PCR) tubes using a real-time turbidimeter. The results indicated that the threshold time obtained using the colorimetric LAMP assay in the developed system is comparable to that obtained with real-time turbidity measurements in PCR tubes, demonstrating the system's capability for quantitative analysis of target nucleic acids, including those from human herpesviruses.

CO2 activation by copper oxide clusters: size, composition, and charge state dependence.

The interaction of CO2 with copper oxide clusters of different size, composition, and charge is investigated via infrared multiple-photon dissociation (IR-MPD) spectroscopy and density functional theory (DFT) calculations. Laser ablation of a copper target in the presence of an O2/He mixture leads to the preferred formation of oxygen-rich copper oxide cluster cations, CuxOy+ (y > x; x ≤ 8), while the anionic cluster distribution is dominated by stoichiometric (x = y) and oxygen-deficient (y < x; x ≤ 8) species. Subsequent reaction of the clusters with CO2 in a flow tube reactor results in the preferred formation of near-stoichiometric CuxOy(CO2)+/- complexes. IR-MPD spectroscopy of the formed complexes reveals the non-activated binding of CO2 to all cations while CO2 is activated by all anions. The great resemblance of spectra for all sizes investigated demonstrates that CO2 activation is largely independent of cluster size and Cu/O ratio but mainly determined by the cluster charge state. Comparison of the IR-MPD spectra with DFT calculations of the model systems Cu2O4(CO2)- and Cu3O4(CO2)- shows that CO2 activation exclusively results in the formation of a CO3 unit. Subsequent CO2 dissociation to CO appears to be unfavorable due to the instability of CO on the copper oxide clusters indicating that potential hydrogenation reactions will most likely proceed via formate or bicarbonate intermediates.

Dehydrogenation of diborane on small Nbn+ clusters.

The reactivity of Nbn+ (1 ≤ n ≤ 21) clusters with B2H6 is studied by using a self-developed multiple-ion laminar flow tube reactor combined with a triple quadrupole mass spectrometer (MIFT-TQMS). The Nbn+ clusters were generated by a magnetron sputtering source and reacted with the B2H6 gas under fully thermalized conditions in the downstream flow tube where the reaction time was accurately controlled and adjustable. The complete and partial dehydrogenation products NbnB1-4+ and NbnB1-4H1,2,4+ were detected, indicative of the removal of H2 and likely BHx moieties. Interestingly, these NbnB1-4+ and NbnB1-4H1,2,4+ products are limited to 3 ≤ n ≤ 6, suggesting that the small Nbn+ clusters are relatively more reactive than the larger Nbn>6+ clusters under the same conditions. By varying the B2H6 gas concentrations and the reactant doses introduced into the flow tube, and by changing the reaction time, we performed a detailed analysis of the reaction dynamics in combination with the DFT-calculated thermodynamics. It is demonstrated that the lack of cooperative active sites on the Nb1+ cations accounts for the weakened dehydrogenation efficiency. Nb2+ forms partial dehydrogenation products at a faster rate. In contrast, the Nbn>6+ clusters are subject to more flexible vibrational relaxation which disperse the energy gain of B2H6-adsorption and thus are unable to overcome the energy barriers for subsequent hydrogen atom transfer and H2 release.

Tempe Wastewater Treatment Using Effective Microorganisms Made from Kepok Banana Peel Waste

Wastewater produced by the tempeh industry contains a high organic content, so it requires serious handling so as not to cause pollution in water bodies. One method that can accelerate the decomposition of the organic substance process is to use Lactobacillus sp. bacteria as effective microorganisms (EM). The material used to manufacture EM is sourced from kepok banana peel waste, which has a carbohydrate content of 9.8%. This study aims to examine the effect of EM concentration and residence time on reducing pollutants in tempeh wastewater using EM made from kepok banana peel waste. The EM concentrations were 0%, 10%, 20%, and 30% successively, with residence times of 0, 4, 8, 12, and 16 days. The researchers used a batch system in a 5-litre plastic tube reactor with an aeration system. The results demonstrated the effectiveness of adding EM from kepok banana peel waste in reducing Chemical Oxygen Demand (COD) levels. Specifically, a 20% dose of EM resulted in a 78.13% removal, a 30% dose of Biological Oxygen Demand (BOD) led to a 78.01% reduction, and a 10% dose of Total Suspended Solid (TSS) resulted in a 66.81% removal over an optimum residence time of 16 days.

Air separation and N2 purification with Ba0.15Sr0.85FeO3-δ via a two-step thermochemical process

Thermochemical air separation to produce high-purity N2 was demonstrated in a vertical tube reactor via a two-step reduction–oxidation cycle with an A-site substituted perovskite Ba0.15Sr0.85FeO3–δ (BSF1585). BSF1585 particles were synthesized and characterized in terms of their chemical, morphological, and thermophysical properties. A thermodynamic cycle model and sensitivity analysis using computational heat and mass transfer models of the reactor were used to select the system operating parameters for a concentrating solar thermal-driven process. Thermal reduction up to 800 °C in air and temperature-swing air separation from 800 °C to minimum temperatures between 400 and 600 °C were performed in the reactor containing a 35 g packed bed of BSF1585. The reactor was characterized for dispersion, and air separation was characterized via mass spectrometry. Gas measurements indicated that the reactor produced N2 with O2 impurity concentrations as low as 0.02 % for > 30 min of operation. A parametric study of air flow rates suggested that differences in observed and thermodynamically predicted O2 impurities were due to imperfect gas transport in the bed. Temperature swing reduction/oxidation cycling experiments between 800 and 400 °C in air were conducted with no statistically significant degradation in N2 purity over 50 cycles.

Plastic Waste Pyrolysis Reactors with Integration of Rocket Stove and Advanced Heat Transfer System: An Analysis of its Design

The development of efficient and sustainable pyrolysis reactors is critical for advancing bioenergy technologies and waste management. This study presents the design and stress analysis of a pyrolysis reactor incorporating a rocket stove and an advanced heat transfer system, using Autodesk Inventor 2016. The integration of a rocket stove ensures efficient combustion and high-temperature stability, while the advanced heat transfer system maximizes thermal distribution within the reactor, enhancing the pyrolysis process. Stress analysis revealed critical stress points and informed design optimizations to ensure durability and safety. This innovative design approach, validated through advanced simulation tools, offers a significant advancement in the development of sustainable and efficient pyrolysis reactors. The safety factor is defined as the ratio of maximum allowable stress to equivalent stress. The permissible stress value for stainless steel components used in pyrolysis tubes is 187.5 MPa. The stress analysis test revealed that the reactor tube experienced a maximum equivalent stress of 17.72 MPa. The reactor’s design, incorporating materials capable of withstanding high temperatures and stresses, ensures safe and reliable operation. Stress analysis and the implementation of appropriate safety factors play a critical role in maintaining the reactor’s structural integrity.

Dry LAMP: A point of care diagnostics for diagnosis of bovine tropical theileriosis.

Theileriosis is an important tick-bome hemoprotozoan disease of cattle which causes severe economic loss due to morbidity and mortality. A diagnostic test having high sensitivity, specificity and easy application at the field level is the need of the hour. In this regard Loop-mediated isothermal amplification (LAMP) is proven to be a sensitive, easy and time efficient method. One of the major obstacles for the application of LAMP is the difficulty in maintaining the cold chain to preserve reagents. Thus, the challenge is to develop a LAMP kit in a ready-to-use format with dried reagents useful for quick and simple application in field conditions. The optimized reaction of wet LAMP was followed for the standardization of dry LAMP with certain modifications which are needful. The major modification is vitrification technology of enzyme using trehalose. LAMP assay (dry and wet LAMP) was found to be more sensitive (100%) when compared to microscopy (69.5%) and PCR (86.9%). It was observed that the dry LAMP reaction tubes at room temperature as well as refrigeration temperature provided successful amplification till 7 weeks. The drying conditions of LAMP reagents were optimized, and finally managed to dry them in a single reaction tube without reducing the sensitivity. This technology enables us to transport LAMP kits to areas where the cold chain is not easily available.

Conjugate heat transfer characteristics numerical simulation on steam generator tube of lead-cooled fast reactor

The safety assessment of the Steam Generator Tube Rupture (SGTR) accident is a crucial step in the design process of the Lead-cooled Fast Reactor (LFR). To begin with, it is necessary to simulate the steady-state heat transfer of the LFR Heat Exchanger (HX) in order to determine the initial conditions of the SGTR accident. In this study, the heat transfer characteristics of the fluids on both sides of the LFR HX are analyzed. The appropriate models are modified based on the heat transfer characteristics of liquid metal and boiling water. The accuracy of the boiling models is verified by comparing the simulation results with the outcomes of boiling heat transfer experiments. Additionally, the simulation results are compared with the results obtained from ATHLET calculation and empirical formulas. On the secondary side, the supercooled water undergoes heating until it reaches the superheated steam phase. The preheating section spans from 0 to 600 mm, the saturated boiling section ranges from 600 to 3000 mm, and the superheating section extends from 3000 to 6600 mm. Ultimately, the distributions of steady-state temperature, pressure, and vapor volume fractions of the LFR HX are determined, providing the necessary initial conditions for the occurrence of the SGTR accident.

Experimental and kinetic modeling study of C5 cyclic hydrocarbons pyrolysis at elevated pressures: Effect of unsaturation on the reactivity and PAH formation

To further explore the decomposition behaviors of C5 cyclic hydrocarbons, important components in the transportation fuels and pivotal intermediates in high-density liquid fuels, the pyrolysis of cyclopentane, cyclopentene and cyclopentadiene with different unsaturation degrees were investigated. The experiments of cyclopentane and cyclopentene were performed at 1.0, 30.0 atm and 773–1173 K in a flow tube reactor. The mole fraction profiles of pyrolysis species, involving C1-C5 small hydrocarbons and monocyclic, bicyclic as well as polycyclic aromatic hydrocarbons (MAHs, BAHs and PAHs), were provided. A universal kinetic model for three C5 cyclic fuels pyrolysis chemistry was proposed and reasonably predicted the speciation profiles newly reported in this work and literature, where rate coefficients of the crucial reactions were compared and upgraded. The differences among three fuels specific pathways were evaluated and the effects of unsaturation on the pyrolysis characteristics of intrinsic reactivity and aromatics formation were revealed. Cyclopentene has the highest pyrolysis reactivity, followed by cyclopentane and cyclopentadiene. Simultaneously formed fuel radicals and key intermediates in three C5 cyclic fuels influence the formation channels of small products, MAHs and BAHs. The saturated cyclopentane is easily occur the ring-opening reaction to generate more C2 and C3 species, whereas the increase in unsaturation promotes MAHs and BAHs formation in cyclopentene and cyclopentadiene pyrolysis, especially the toluene, styrene, indene and naphthalene. The rate of production analysis shows the formations of these MAHs and BAHs are strongly dependent on the concentration levels of cyclopentadienyl resonance stabilized radical (RSR). Differently, the dominated growth pathways of three- and four-ring PAHs are barely influenced by the specific fuel chemistry and indenyl plays a crucial role via the typical RSR chain reactions at high pressures.

Reaction between Criegee Intermediate CH2OO and Isobutyraldehyde: Kinetics and Atmospheric Implications

AbstractIn the present work, we have investigated the 1,3‐cycloaddition reaction of isobutyraldehyde ((CH3)2CHCHO) with the simplest Criegee intermediate CH2OO using the OH laser‐induced fluorescence (LIF) method in a reaction tube. The experiments were conducted at temperatures and pressures ranging from 280 to 338 K and 5 to 150 Torr. We found that the bimolecular rate coefficient of the reaction is temperature‐ and pressure‐dependent. The measured rate coefficients at 100 Torr are (4.93±0.89), (4.46±0.80), (3.99±0.72), (3.56±0.64), (3.34±0.60), (2.98±0.54), (2.78±0.50)×10−12 cm3 molecule−1 s−1 at 280, 288, 298, 308, 318, 328, and 338 K, respectively. A high‐pressure limit rate coefficient of (4.47±0.80)×10−12 cm3 molecule−1 s−1 was obtained at 298 K by fitting the pressure‐dependent rate coefficients according to the Lindemann mechanism. The Arrhenius plot of the temperature‐dependent rate coefficients results in an activation energy of (−1.86±0.33) kcal mol−1 and a preexponential factor of (1.72±0.31)×10−13 cm3 molecule−1 s−1. In the atmosphere, the reaction of CH2OO with isobutyraldehyde may contribute to the sink of CH2OO in regions where isobutyraldehyde emission is intense under low temperature and low relative humidity conditions.

In-situ synthesis of carbon nanotubes-graphite hybrid materials

This contribution deals with a commercially scalable catalyst preparation method for the synthesis of a new generation of hybrid materials based on carbon-nanotubes-graphite. Commercial natural graphite in spherical or flake shapes, with varying particle sizes and textural properties, were used as catalyst support. They were impregnated with aqueous solutions containing cobalt nitrate in the presence of a non-ionic surfactant agent and then dried and calcined under controlled experimental conditions. Catalytic activity properties were evaluated in a rotary tube reactor using ethylene as a carbon source at a temperature of 650 °C and a residence time of 5 min. It was observed that the use of a surfactant agent in the impregnation step significantly improved the adsorption and dispersion of the active metal on the hydrophobic catalyst support surface, enabling the formation of a dense coating of carbon nanotubes on the graphite particles after the synthesis. The multi-walled carbon nanotubes (MWCNTs) showed diameters ranging from 10 to 20 nm and lengths between 5 and 10 µm, with most of them growing via the base-mode growth mechanism. The morphology properties of the graphite particles play a key role in influencing the active metal surface deposition, the MWCNT yield, and their aspect ratio properties

A 3D-printed oscillatory polymerase chain reaction system using a single heater

Nucleic acid amplification is a process that arises in all organisms. Polymerase chain reaction (PCR) is a standard laboratory nucleic acids amplification technology in vitro widely used in medical detection and biometric-related research. This device represents the first demonstration of 3D-printed oscillatory thermocycling within a portable PCR device. This study uses a single Peltier element to create the three temperature regions required for PCR. The overall control system uses an Arduino microcontroller with the advantages of easy development, abundant resources, and easy access to device software design. The sample-driving system integrated with the 3D printed object and the laser-cut acrylic component to achieve the linear reciprocating motion of the sample is conducive to the realisation of the portable design of the device. After system optimisation, the reaction tube moves from the denaturation zone to the aluminum block for cooling, and it moves to the groove of the denaturation zone from the annealing zone to accelerate the sample temperature rise. The time duration reduces from 180 s to 85 s to complete one thermal cycle. Combining the 5 mm instead of 3 mm thickness of the acrylic material and the configuration of the acrylic end exposed in the air creates a more significant temperature difference from 25 °C to 40 °C. Using this oscillatory PCR device, we successfully amplified a 219 bp PCR product of turmeric DNA after 30 thermal cycles within 50 min. The developed PCR device will cost less than $300 USD in our work. Compared with previous works, the cost of this research device is relatively low, and the total volume of the device is quite small. This work should be interesting to persons involved in diagnosing the infectious diseases of viruses and bacteria and identifying the fake healthy food in the low-cost bioreaction chambers in fields and remote areas.

Physical aspects of the fire and explosion hazard of combustible dust. Part 2. Self-wave modes of combustion

In present review, based on the authors' long-term research, generalized ideas about the ignition patterns andmetal dust wave burning are given. The first part discusses patterns of ignition as a result of the action of non-linearthermokinetic type factors (Arrhenius dependence). The second part analyzes the flame propagation patterns in dust caused by the presence of hydrodynamic nonlinearities in the active system, which lead to the existence of laminar, vibrational, and turbulent flames. The influence of physico-chemical parameters (type, dispersion, concentration of fuel) andflame propagation hydrodynamic conditions (reaction pipes of different diameters and lengths, dust clouds with a volume of 10 ÷ 40 m3) on theindicated modes implementation and their characteristics are discussed.&#x0D; For laminar flames, the main focus is on the problem of normal flame speed and flame propagation concentration limits. For a vibrating flame (reaction tubes were ignited at the open end of a semi-closed tube), the regularities of cascade transitions are analyzed – laminar flame ↔ vibrational type I ↔ vibrational type II ↔ turbulent flame.

The Study of Fluid Dynamics Simulation of the Internal Flow Field in a Novel Airlift Oscillation Loop Bioreactor

The three-dimensional flow and mass transfer conditions in 5 L and 40 L airlift oscillation loop reactors were studied and compared with existing two-dimensional simulation and experimental data to verify the accuracy of the method. Then, the fluid dynamics behavior of the 2500 L reactor was simulated via supercomputing and provided guidance for production data. The results indicate that the application of oscillation operation in the 40 L multi-guide tube reactor can effectively improve the gas holdup and mass transfer coefficient in the reactor, with a maximum increase of 38% and 29%. For the 2500 L multi guide tube reactor, oscillation operation oscillation operation can significantly improve gas holdup and mass transfer coefficient increase gas holdup by 46% under 0.5 vvm operating conditions; the mass transfer coefficient increased by 54%. Therefore, oscillation operation can greatly improve the mass transfer coefficient for actual production reactors. After digging a hole in the middle sleeve, the circulating liquid speed has no effect. Although the gas holdup and mass transfer coefficient decreased by 1.3%, the gas holdup inside the entire reactor was more uniform, effectively reducing the average bubble aggregation.

Homogeneous oxidation of SO2 in the tail gas incinerator of sulfur recovery unit

The formation and emission of sulfur trioxide (SO3) in sulfur recovery unit has received increasing attention due to its adverse effects on the operation of plant and environment. Due to the excess oxygen, high concentration of SO2 and high temperature, SO3 formation in the sulfur recovery unit tail gas incinerator may significantly increase. A small horizontal tube reactor was employed to simulate the homogeneous oxidation of SO2 in the tail gas incinerator. The SO3 concentration was measured with a controlled condensation method at the outlet of the reactor. The present work focuses on the gas-phase chemistry and examines the impact of different combustion parameters and atmospheres on the formation of SO3 in the tail gas incinerator. Experiment results show that the increased O2 and SO2 concentrations along with increasing temperature are favorable for enhancing SO3 formation over the range of tested parameters. The presence of water vapor has an enhancing effect of SO2 oxidation in the experiments conducted. No significant effect of CO2 was found to the oxidation of SO2.

Effect of methyl substituent on adamantane pyrolysis at atmospheric and high pressure: A combined experimental and theoretical study

Adamantane derivatives, as promising high-density fuels, have been widely concerned in fields of volume-limited aerospace vehicles due to high density, heat of combustion and thermal oxidation stability. To reveal insights into their high-temperature decomposition behaviors, an experimental and theoretical investigation of adamantane (A) and 1-methyl adamantane (1-MA) pyrolysis was performed in a flow tube reactor at atmospheric to high pressure. Over twenty species were detected and identified, including C1-C5 light hydrocarbons, C5-C7 cyclic olefins as well as C6-C12 aromatics. The favorable decomposition channels of A and 1-MA are proposed and the effects of fuel structure characteristics and pressures on product formation behaviors are revealed. For the primary decomposition of A and 1-MA, the contributions of reaction types exhibit the obvious dependence on the pressures and temperatures, involving the unimolecular C-C dissociations by ring-opening, CH3-elimination as well as H-abstractions by H and CH3 attacking. Considering methyl-substitution weakens dissociation energies of C-C and C-H bonds and leads more H-abstraction sites, 1-MA shows a higher pyrolysis reactivity than A. The effects of structure characteristics are also embodied in the formation of newly chain-branched unsaturated species and the concentrations of common small hydrocarbons and aromatics. Compared to A decomposition, the methyl substituent in 1-MA promotes the emergence of 1-butene, 2-methyl-1-butene, mesitylene, methylindane and methylnaphthalene, and increases the concentrations of methane, 2-methylpropene and xylene isomers, formed via β-scission, hydrogen transfer, isomerization and dehydrogenation routes of fuel radicals. Meanwhile, more methyl-substitutions accelerate the decomposition of alkyl-adamantanes and pyrolysis activity follows by a sequence of dimethyl-adamantane > methyl-adamantane > adamantane, boosting the production of methyl-specific species.