Increasing Mole Fraction Research Articles

Computational investigation of combustion and emission characteristics of HCCI engine fueled with Carbon-Free NH3 –H2O2 blend

A computational investigation is provided of the utilization of blends of NH3 and H2O2 as carbonless fuels for HCCI combustion. A Computational Fluid Dynamics (CFD) model is developed and validated to assess the engine’s performance under varying proportions of NH3 and H2O2, equivalence ratios, and inlet temperatures. The heat release rate profiles demonstrated dual peaks, which were rationalized as an initial fuel decomposition followed by a slow thermal explosion and then a fast depletion of the fuel after the generation of a pool of OH radicals through decomposition of H2O2. Findings suggest that an increase in mole fraction of H2O2 advances combustion. Increasing the H2O2 volume fraction also decreases combustion duration, while increasing the IMEP. In-cylinder peak pressure and Maximum Pressure Rise Rate (MPRR) increase with H2O2 mole fraction, leading to reduced thermal efficiency, particularly at higher equivalence ratios, and an increased danger of uncontrolled combustion (knocking). Additionally, higher inlet mixture temperatures were shown to result in an advancement in the start of combustion and a reduction in combustion duration, with a corresponding increase in peak pressure. This points to the possibility of potentially controlling the notoriously difficult-to-control HCCI combustion through intake temperature for NH3/H2O2 fuel blends. However, increased NOx emissions are observed for increased intake temperature and in any case the NOx emissions are orders of magnitude above current regulatory limits, which means that practical engine operation will only be possible with an aftertreatment scheme based on the de-NOx activity of NH3.

Numerical investigation of non-equilibrium condensation of carbon dioxide from a gas mixture of carbon dioxide and argon in a supersonic nozzle under cryogenic conditions

This study involved a numerical investigation of the homogeneous nucleation of CO2 from a CO2–Ar gas mixture in a supersonic nozzle with a throat size of 2.11 mm, a total pressure of 61.15 kPa, and a total temperature of 293.15 K. The flow conditions covered the cryogenic temperature range (∼75 K). Therefore, the surface tension of the clusters was calculated using the Tolman–Tanaka correction, and nucleation growth was evaluated considering both free molecular and continuum regimes. Numerical simulations were conducted for a wide range of CO2 mole fractions (3%–39%). In particular, the effect of the CO2 mole fraction on the condensation-shock position—approximately the Wilson point—was investigated. For 3%, 12%, 24%, and 39%, the condensation shock occurred at 0.048, 0.043, 0.046, and 0.054 m from the throat, respectively. When the mole fraction was low (≤10%), the condensation-shock position moved downstream as the mole fraction decreased. This trend was attributed to a lower nucleation rate. In contrast, when the mole fraction was high (≥10%), the condensation-shock position moved downstream as the mole fraction increased. This was because the CO2 equilibrium pressure rose more rapidly than the CO2 vapor pressure as the mole fraction increases.

Effects of elevated oxygen content and temperature on the laminar burning velocity of the blast furnace gas in oxygen-enriched air condition

Oxygen-enriched air combustion holds promise as an effective method for harnessing blast furnace gas (BFG) in the steel industry. In this study, the laminar burning velocities of blast furnace gas were measured using the heat flux method under elevated oxygen mole fractions (0.3–1.0) and temperatures (303–353 K). Subsequently, the measured data were used to evaluate the GRI-Mech 3.0, Li, FFCM-1, and Konnov 2023 mechanisms. Comparisons between experimental and calculated laminar burning velocities revealed that the Konnov 2023 mechanism well predicts the experimental data at all conditions, while the predictions of the other three mechanisms deviate from the experimental data. The laminar burning velocities of blast furnace gas increased with elevated oxygen mole fraction and temperature. Interestingly, the peak of laminar burning velocity shifts from the fuel-rich side to the fuel-lean side with an increase in oxygen mole fraction, which is mainly due to the fuel-lean shift peak of adiabatic flame temperature and the higher diffusive properties of the gas mixture at fuel-rich side. The reaction CO+OH<=>CO2 + H emerges as the most significant reaction influencing laminar burning velocities. The elevated oxygen mole fraction reduces the dependence of the power exponent α on the fitted temperature range. Corresponding oxygen mole fractions for the blast furnace gas are determined to be 0.59 at φ = 0.8 and 0.93 at φ = 0.9, respectively, at which the laminar burning velocity of the BFG/O2/N2 mixture equals that of the CH4/Air mixture.

The response of mesophyll conductance to short-term CO2 variation is related to stomatal conductance.

The response of mesophyll conductance (gm) to CO2 plays a key role in photosynthesis and ecosystem carbon cycles under climate change. Despite numerous studies, there is still debate about how gm responds to short-term CO2 variations. Here we used multiple methods and looked at the relationship between stomatal conductance to CO2 (gsc) and gm to address this aspect. We measured chlorophyll fluorescence parameters and online carbon isotope discrimination (Δ) at different CO2 mole fractions in sunflower (Helianthus annuus L.), cowpea (Vigna unguiculata L.), and wheat (Triticum aestivum L.) leaves. The variable J and Δ based methods showed that gm decreased with an increase in CO2 mole fraction, and so did stomatal conductance. There were linear relationships between gm and gsc across CO2 mole fractions. gm obtained from A-Ci curve fitting method was higher than that from the variable J method and was not representative of gm under the growth CO2 concentration. gm could be estimated by empirical models analogous to the Ball-Berry model and the USO model for stomatal conductance. Our results suggest that gm and gsc respond in a coordinated manner to short-term variations in CO2, providing new insight into the role of gm in photosynthesis modelling.

Study on the minimum miscibility pressure and phase behavior of CO2–shale oil in nanopores

In recent years, CO2 enhanced oil recovery has gained traction in shale oil reservoirs. Shale oil reservoirs are characterized by numerous nanopores, where shale oil exhibits unique phase behavior due to nano–confinement effects. Traditional theoretical model and microfluidic experiment often fail to accurately depict the minimum miscible pressure (MMP) of CO2–shale oil in nanopores. In this study, nanofluidic experiments were conducted to investigate the MMP of CO2–alkanes in single pore channels and porous media channels with depths of 30 nm and 100 nm. Additionally, a novel thermodynamic model of gas–liquid–adsorbed phase equilibrium, which considers the capillary force and the shift in the critical property, was developed by integrating simplified local density functional theory. The feasibility of the method was determined by comparing the measured MMP with the MMP obtained using the newly established thermodynamic model, resulting in errors of 10.804 % and 5.545 %. Finally, phase behavior and MMP for two typical oil samples in block A in China were conducted using the newly established thermodynamic model. The results revealed that as the pore radius decreases, the area of the two–phase region enclosed by the phase envelope contracts progressively. In addition, the saturation pressure decreases gradually for shale oil with a higher content of light components as the molar fraction of the injected CO2 increases, whereas for shale oil with higher heavy component content, it increases as the CO2 molar fraction increases. The MMP of CO2–shale oil in 10 nm pores is 70.188 bar at 392.75 K of sample 1 and 83.007 bar at 374.72 K of sample 2. Compared to the bulk phase, the MMP was reduced by 63.76 % and 57.64 %.

Digital Light Processing Resins with Programmable Shape Memory for Biomedical Applications.

The creation of biodegradable and biocompatible shape memory polymers amenable to biofabrication techniques remains a challenge. The ability to create shape-changing biodegradable objects that are triggered at body temperature opens up possibilities in tissue engineering, minimally invasive surgery, and actuating bioimplants. Merging Digital Light Processing (DLP) printing with shape memory polymers brings us closer to new smart biomedical outcomes. Previously, we developed a poly(caprolactone-co-trimethylenecarbonate) urethane acrylate resin for the DLP fabrication of biodegradable 3D objects. In further studies, we observed that some of these resins possessed shape memory properties, triggered by body temperature (37 °C). In this subsequent study, we explored the shape memory properties and tunability of this resin family via changes in copolymer composition, molecular weight, and identity of the acrylate end-capping unit. We found that we could create a library of shape memory resins, amenable to DLP printing, which allowed the creation of shape-actuating structures with some tunability over the speed of shape memory and mechanical properties. We observed that increased mole fraction of caprolactone in the copolymer and increased molecular weight of the polymer led to a decrease in speed of the shape memory switch. Furthermore, we observed a trade-off between the composition and the end-capping moiety on the mechanical properties of the polymers. These polymeric resins were able to be processed into shapes that were able to perform work, including the release of cargo and grabbing/lifting of an object. This platform now provides a way to tune the speed and mechanical properties of a shape memory DLP object created from common and scalable polymerization techniques. This work ultimately provides a new platform to develop customizable and biodegradable devices capable of actuating and delivery devices for numerous biomedical applications.

Physicochemical properties of binary mixtures of cation-fluorinated ionic liquids with their non-fluorinated analogues

This work reports an investigation of the physicochemical properties (density, viscosity, refractive index and thermal stability) of four binary mixtures having a common acetate ([OAc]¯), trifluoromethanesulfonate ([OTf]¯) or bis(trifluoromethylsulfonyl)imide ([NTf2]¯) anion with either cation-fluorinated and non-fluorinated methylimidazolium (MIm) or pyridinium (Py) cations respectively, at various temperatures. The mixing behaviour of the binary mixtures was analysed by 1H and 19F Nuclear magnetic resonance (NMR) spectrometry, and the excess properties of the mixtures were calculated from the physicochemical data. The binary mixtures of fluorinated ionic liquids (FILs) with their non-fluorinated or alkyl-substituted analogues (AILs) showed an increase in density and viscosity but a decrease in refractive index with an increase in mole fraction of the pure FILs. The thermal stability of the AILs was higher than the FILs, however, an increase in the mole fraction of the pure FILs in the binary mixtures made a negligible impact on the thermal stability of the binary mixtures. These binary mixtures were found to deviate from ideal behaviour for the different physicochemical properties tending to vary between the extremes of the pure components. The large differences in properties of FILs compared with their non-fluorinated analogues were shown to be associated with the size of the fluorine atoms in the fluoro-alkyl chain, the tendency of the fluoro-alkyl chain to form aggregates with fluorinated anions, and the hydrogen bond acceptor strength of the anions. The excess properties were fitted to the Redlich-Kister polynomial equation, and no significant deviation was obtained. This study shows that the physicochemical properties of the fluorinated ionic liquids can conveniently be adjusted for specific applications by simply varying the amount of the cation-fluorinated component in binary mixtures.

Thermodynamic analysis of a novel gas separator based on molecular exchange flow

An energy analysis model and several evaluation indexes are established for a novel gas separator employing molecular exchange flow as working principle. The influences of several important factors on energy consumption and thermal efficiency are investigated. As temperature difference increases, both energy consumption and thermal efficiency rise linearly. As Knudsen number increases, total work decreases while minimum separation work and thermal efficiency initially increase and subsequently decrease. When inlet velocity increases, total work increases but minimum separation work and thermal efficiency go down. Furthermore, both energy consumption and thermal efficiency initially rise and then decline with an increasing mole fraction of the lighter molecular weight component. The results indicate that energy consumption and separation performance should be taken into consideration when selecting temperature differences. In addition, it is preferable to choose the Knudsen number corresponding to optimal separation performance and the intermediate value for component mole fraction. Moreover, it had better employ a lower inlet velocity as long as the separation requirements are satisfied. This study presents a method to optimize the performance of the novel separator based on molecular exchange flow from the perspective of energy conversion and utilization.

Physicochemical Studies on Amino Acid Based Metallosurfactants in Combination with Phospholipid.

Dicarboxylate metallosurfactants (AASM), synthesized by mixing N-dodecyl aminomalonate, -aspartate and -glutamate with CaCl2, MnCl2 and CdCl2, were characterized by XRD, FTIR, and NMR spectroscopy. Layered structures, formed by metallosurfactants, were evidenced from differential scanning calorimetry and thermogravimetric analyses. Solvent-spread monolayer of AASM in combination with soyphosphatidylcholine (SPC) and cholesterol (CHOL) were studied using Langmuir surface balance. With increasing mole fraction of AASM mean molecular area increased and passed through maxima at ~60 mol% of AASMs, indicating molecular packing reorganization. Systems with 20 and 60 mol% AASM exhibited positive deviations from ideal behavior signifying repulsive interaction between the AASM and SPC, while synergistic interactions were established from the negative deviation at other combinations. Dynamic surface elasticity increased with increasing surface pressure signifying formation of rigid monolayer. Transition of monolayer from gaseous to liquid expanded to liquid condensed state was established by Brewster angle microscopic studies. Stability of the hybrid vesicles, formed by AASM+SPC+CHOL, were established by monitoring their size, zeta potential and polydispersity index values over 100 days. Size and spherical morphology of hybrid vesicles were confirmed by transmission electron microscopic studies. Biocompatibility of the hybrid vesicles were established by cytotoxicity studies revealing their possible applications in drug delivery and imaging.

An Insight in the Viscosity–Temperature Property of CaO‐SiO2‐Al2O3‐Based Slag Systems from Melt Structure

Viscosity is an important property for CaO‐SiO2‐Al2O3‐based slag systems, which showcases different scenarios in basic and acid slag systems with temperature change. This article elucidates the mechanism of their difference in viscosity–temperature property from melt structure. Results reveal that basic slag shows a low degree of polymerization (DOP) and a low viscosity of the melt due to an excessive O2− ions depolymerizing the complex network structures, resulting in more low‐polymerized Q0(Si) units and less high‐polymerized Q3(Si) units. With the temperature decreases, the DOP and viscosity do not change significantly. However, the low DOP and viscosity favor crystal precipitation in the melt, leading to a solid–liquid mixed state of the slag, and thus a sharp increase in viscosity when the temperature decreases to 1275 °C. For acid slag, it undergoes a transformation into aluminosilicate structures with the introduction of numerous [AlO4]5− tetrahedra, accompanied by a significant increase in the relative mole fraction of high‐polymerized Q3(Si) units. Consequently, the DOP and viscosity are obviously higher than that of the basic slag. Furthermore, the DOP and viscosity of the acid slag increase continuously with the temperature decreasing, thus impeding crystal precipitation and enhancing the glass transition tendency of the molten slag.

Prediction of Phase Equilibrium Conditions and Thermodynamic Stability of CO2-CH4 Gas Hydrate

With the large-scale promotion and application of CO2 flooding, more and more engineering problems have emerged. Due to the high CO2 mole fraction, the associated gas of CO2 flooding very easily forms solid hydrates, compared to conventional natural gas. This has resulted in production decline or shutdown. Understanding the phase equilibrium conditions for hydrate formation in production fluids is crucial for hydrate prevention and control. In this study, accurate predictions of CO2-CH4 mixed gas hydrate formation conditions were performed using theoretical models. The temperature and pressure ranges for hydrate formation were calculated for different CO2 mole fraction, ranging from −11.5 °C to 20.85 °C and from 0.81 MPa to −28.1 MPa, respectively. Based on the calculated phase equilibrium data, a multi-parameter empirical model was developed using polynomial fitting. The calculation errors for the multi-parameter empirical model were 3.09%. The multi-parameter empirical model established in this study can avoid complex thermodynamic equilibrium calculations and has the advantages of simplicity, high accuracy, and wide coverage of downhole conditions. Based on the calculated phase equilibrium data, the dissociation enthalpy of CO2-CH4 hydrate below and above the freezing point of water was calculated. The results showed that an increase in CO2 mole fraction led to an increase in hydrate dissociation enthalpy and enhanced thermodynamic stability, making hydrate prevention more challenging. Our work can contribute to the optimization of CO2 production fluid treatment processes and the development of hydrate prevention and control technologies.

Parameters estimation of fabricated polysulfone membrane for CO2/CH4 separation

The emission of CO2 into the climate due to factory operations is a major health and environmental concern. The simplicity and cost-effectiveness of membrane-based gas separation make it a competitive industrial gas separation technology. However, further research is necessary to study fabrication and theoretical simulations membrane performance. There is also a research gap in analyzing different membrane designs and operational factors that affect gas separation performance. Therefore, this study employed computational fluid dynamics (CFD) to assess the polysulfone (PSF) fabricated membrane, considering four proposed operational and design factors. The CFD predicts the concentration and velocity distribution of the components. Fick's law is employed to represent the gas transport process over the membrane, while the Navier-Stokes equation is utilized to drive the flow of gases in both the inlet and permeate sides of the permeation unit. The outcomes of gas flow rate, temperature, pressure, and diameter of the membrane module on the CO2 mole fraction were investigated. Furthermore, at a high gas flow rate, the CO2 mole fraction increase in permeate. Increasing the feed temperature from 313 to 393 K results in a decrease in the CO2 mole fraction at the permeate side from 39% to 36%. The CO2 mole fraction at the site of permeation slightly decreases as the pressure increases. However, increasing the inside diameter of the cell membrane improves the mole fraction of CO2. According to the findings, the CFD model provides a valuable study on the influence of operating and design factors on a gas separation unit.

A kinetic model of diffusional phase transformations in ternary line compounds and determination of diffusion coefficients: Application to the Nb–Mo–Si system

The diffusional phase transformations in inhomogeneous multicomponent systems play an important role in affecting the material properties. Ternary line compounds, which are ternary phases with components that have both large and small solid solubility, are often observed in applications. They are different from solid solutions with variable composition ratios and stoichiometric compounds with fixed composition ratios. However, the existing models cannot quantitatively characterize the diffusional phase transformations in ternary line compounds. Therefore, by introducing the state equation related to the chemical potential and mole fraction, a kinetic model of diffusional phase transformations was established for the first time to describe the mole fraction evolution and phase growth in ternary line compounds. Furthermore, a method to determine the tracer diffusion coefficients of components related to the mole fraction and crystal phase structure in ternary line compounds was proposed, and applied to the diffusion of Nb-Mo-Si ternary system composed of the MoSi2 and Nb. During the high-temperature diffusion process of Nb-MoSi2, the silicide-poor phase (Mo, Nb)5Si3 is formed, which is a typical ternary line compound. Based on the diffusion experiments and inverse calculations, the tracer diffusion coefficients of components in ternary line compound (Mo, Nb)5Si3 were experimentally obtained. Moreover, ab-initio calculations of defect energetics clarified the microscopic diffusion mechanisms in the silicide-poor phase, and explained the reason why that the diffusion coefficient of Si decreases significantly with the increase of Nb mole fraction in ternary line compound (Mo, Nb)5Si3. The research provides valuable guidance for modeling and analyzing the diffusional phase transformation of multi-component systems.

Sustainable co-valorization of medical waste and biomass waste: Innovative process design, optimization and assessment

A novel co-valorization process integrating plasma gasification and Fischer-Tropsch synthesis is designed for converting medical waste (MW) and biomass waste (BMW) into mixed e-fuels where the additional required hydrogen is supplied by solar-based electrolysis. Optimization and comprehensive assessments have been conducted for three scenarios with different ratios of BMW. Operations optimization based on genetic algorithm (GA) has led to a remarkable enhancement in the quality of syngas, with a more than 10% increase in H2 mole fraction. Techno-economic analysis reveals the net present values (NPVs) of three scenarios are −2.56 MM$, 3.38 MM$ and 40.1 MM$ with internal rates of return of 3.4 %, 9.5 % and 14.0 %. By improving the subside of MW treatment, the economic viabilities of all scenarios have been enhanced significantly with higher positive NPVs. Environmental assessment shows ∼2.5 kg eqCO2/kg waste and ∼0.1 g eqCO2 per MJ fuel have been generated across the system boundary and the operation of the designed process has been identified to be the largest source of emissions. These findings underscore the potential of our integrated approach to efficiently convert MW and BMW into valuable e-fuels while maintaining a focus on environmental sustainability.

Maximization of 3-hydroxyhexanoate fraction in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) using lauric acid with engineered Cupriavidus necator H16

As polyhydroxybutyrate (P(3HB)) was struggling with mechanical properties, efforts have been directed towards increasing mole fraction of 3-hydroxyhexanoate (3HHx) in P(3HB-co-3HHx) to improve the properties of polyhydroxyalkanoates (PHAs). Although genetic modification had significant results, there were several issues related to cell growth and PHA production by deletion of PHA synthetic genes. To find out easier strategy for high 3HHx mole fraction without gene deletion, Cupriavidus necator H16 containing phaC2Ra-phaACn-phaJ1Pa was examined with various oils resulting that coconut oil gave the highest 3HHx mole fraction. When fatty acid composition analysis with GC–MS was applied, coconut oil was found to have very different composition from other vegetable oil containing very high lauric acid (C12) content. To find out specific fatty acid affecting 3HHx fraction, different fatty acids from caproic acid (C6) to stearic acid (C18) was evaluated and the 3HHx mole fraction was increased to 26.5 ± 1.6 % using lauric acid. Moreover, the 3HHx mole fraction could be controlled from 9 % to 31.1 % by mixing bean oil and lauric acid with different ratios. Produced P(3HB-co-3HHx) exhibited higher molecular than P(3HB-co-3HHx) from phaB-deletion mutant. This study proposes another strategy to increase 3HHx mole fraction with easier way by modifying substrate composition without applying deletion tools.

Modeling and analysis for enhanced hydrogen production in process simulation of methanol reforming

ABSTRACT Hydrogen has emerged as the most suitable fuel for a nation’s greener and sustainable development. In contrast, the feedstock and hydrogen production methods remain a concern for environmental pollution. This study uses methanol as the feedstock for hydrogen production via a low-temperature methanol-reforming process. A simulation model was developed in Aspen Hysys, where an equilibrium reactor is used in the reforming process, and examined the effects of parameters like temperature, pressure, and Methanol-to-Water (M-to-W) molar ratio. Hydrogen mole fraction and selectivity increase by roughly 18.5% and 10.5% when the reaction temperature increases from 100°C to 400°C. At the same time, the methanol conversion rate reaches 95% at 400°C. Reactor pressure shows inverse effects where pressure rises from 1 atm. to 7 atm. that reduces hydrogen mole fraction and selectivity by about 10% and 6%, and a similar reduction of 5% is noticed in the methanol conversion rate. M-to-W molar ratio plays a crucial role in the reaction pathway and the M-to-W ratio between 0.5 and 1.5 at 400°C and 1 atm. reactor pressure showed the highest hydrogen mole fraction (>0.57) and a maximum methanol conversion rate (>90%). Therefore, the present simulation model successfully determines the impacts of various parameters to help design a commercial plant for large-scale hydrogen production via the reforming process.

A novel 3D fine-mesh flow field design and performance analysis for proton exchange membrane fuel cells

Optimizing flow field structures plays a crucial role in enhancing the mass transfer of reactant gas and improving the output power density of proton exchange membrane fuel cells (PEMFCs). Herein, a PEMFC model with a three-dimensional (3D) fine-mesh flow field is developed and investigated in detail using a 3D computational fluid dynamics (CFD) model. The flow velocity, oxygen partial pressure and oxygen molar fraction distribution in the 3D fine-mesh flow field are analyzed and compared with the parallel flow field. The numerical simulation results show that as the porosity of the 3D fine-mesh structure increases, the local flow velocity increases, the oxygen partial pressure drop decreases, and the oxygen molar fraction increases, which are conducive to improving the output performance of fuel cells. At an operating voltage of 0.4 V, the peak power density of the 3D fine flow field model with a porosity of 0.9 is 21.5% higher than that of the parallel flow field model.

Investigating the effect of spray system on the containment condition of VVER1000/V446 NPP during LBLOCA and TLOFW accidents

The containment system serves as the last barrier against the release of fission products. However, over pressurization or hydrogen detonation can compromise its effectiveness, as evidenced by the Fukushima nuclear power plant (NPP) disaster. This study describes the efficacy of the spray system in reducingcontainment pressure andtemperature, as well as,itsimpacton hydrogen mitigation during large break loss of coolant accident (LBLOCA) and total loss of feed water (TLOFW) accident in the VVER-1000/V446NPP. The evaluation is conductedusing theMELCOR 1.8.6code.The results of the LBLOCA analysis demonstrate that the spray system significantly reduces the pressure and temperature of the containment. It also enhances hydrogen mitigation by increasing the amount of recombined hydrogen by around 4% and reducing the onset time of hydrogen recombination by 90,000 s. In the TLOFW accident scenario, the spray system is effective in reducing the containment pressure from 0.41 MPa to 0.27 MPa. The investigation of hydrogen behavior in the reactor containment atmosphere reveals that the simultaneous operation of the spray and the hydrogen recombiner systems is the most effective strategy for hydrogen mitigation. However, activating the spray system without the passive autocatalytic recombiners (PARs) function can lead to an increase in the hydrogen mole fraction in all containment compartments, thereby increasing the likelihood of hydrogen combustion.

Explosion limit of hydrogen/oxygen mixture with water vapor addition

The explosion limits of H2/O2/H2O mixtures with different equivalence ratios are studied. It is shown that the explosion limit of the H2/O2/H2O mixture exhibits the similar Z-shape as that of the H2/O2 explosion limit. As the H2O mole fraction increases, both the first and second limits move towards higher temperatures. Temperature sensitivity analysis and reaction pathway analysis indicate that the third-body reaction related to H2O and the wall destruction of H/O are responsible for the first limit shift to higher temperatures. The second limit moves to higher temperatures due to the enhanced chain termination reactions related to H and HO2, as well as the wall destruction of H, which simultaneously weakens the pathway for the production of O/OH. However, the third limit moves towards lower temperatures when the H2O mole fraction is 0.1–0.3, and then towards higher temperatures when it is greater than 0.3. The reaction path analysis indicate that the addition of H2O promotes the generation of OH. The physical and chemical effects caused by H2O are also studied. The results show that the inert H2O, which does not participate any reactions, causes the first and third limits towards higher temperatures, while the second limit move to lower temperatures. The physical effects and chemical effects caused by H2O result in the non-monotonic movement of the third limit. Compared with above stoichiometric conditions, the first and second limits of the lean mixtures are at lower temperature, whereas the third limit at higher temperatures. The rich mixtures exhibit opposite tendencies.

Gradation control in the hydrodynamic diameters of mixed glycan-aglycan glycovesicles

Abstract Glycovesicles mimic synthetic cell membrane surfaces and aid to delineate intricate, weak carbohydrate–protein interactions. In this report, the dependence of the hydrodynamic diameters in relation to the molar fractions of carbohydrate moieties in the mixed polydiacetylene (PDA) glycovesicles is evaluated. The glycovesicles are constituted with diacetylene monomers of varying molar fractions of carbohydrate moieties and the hydrodynamic diameters are assessed without and with polymerization of the vesicles. A strong dependence of the hydrodynamic diameter of glycovesicles is seen as a function of the molar fractions and the nature of the sugar moiety being either mono- or disaccharide. A monotonous increase in the hydrodynamic diameters of the glycovesicles occurs with the increase in mole fractions of the sugar monomer lipids. Upon polymerization, the hydrodynamic diameters reduce for the vesicles with lower mole fractions of sugar monomer, whereas the reverse occurs for glycovesicles possessing higher mole fractions. Disaccharide glycovesicles possess higher hydrodynamic diameters than monosaccharide-containing vesicles. Ligand–lectin interactions were probed with lactose disaccharide-containing glycovesicles with tetrameric peanut agglutinin lectin, from which an increase in the hydrodynamic diameters is observed, as the mole fraction of sugar monomer is increased in the PDA-glycovesicles.