Composition Of Initial Mixture Research Articles

Optimizing composting process through mixture design for a sustainable valorization of residual biomass from medicinal and aromatic plants

Abstract Recently, medicinal and aromatic plants (MAP) gained a particular interest for their application in various fields such as food science, pharmacy, etc). MAP processing results in huge amounts of residual biomasses (RB). Such RB are valuable as they contain nutrients that can be recycled into high-value products rather than being considered waste. Composting emerges as a promising solution, effectively converting this biomass into a nutrient-rich product essential for plant growth. This research aimed to valorize RB from MAP through co-composting with green waste (GW) and poultry manure (PM) by optimising the initial mixture composition and evaluating the compost’s quality. A statistical mixture design approach was utilized to optimize the initial mixture composition. Sixteen of experiments were performed, focusing on pH and C/N ratio as response parameters. After monitoring the composting process, physicochemical parameters and the quality of the compost produced were evaluated. The results led to the successful development and validation of two response models using analysis of variance. The ideal mixture composition was found to be 45% RB-MAP, 25%PM, and 30% GW. The final compost exhibited a low C/N ratio, was rich in fertilizing and nutritive elements, and importantly, showed no phytotoxic effects. This research underscores the potential of composting as a sustainable method to convert RB into valuable agricultural resources.

Reforming of ammonia and ammonia-air mixtures in a homogenous plasma reactor: Parametric study of hydrogen yields

Plasma-assisted reforming shows great promise for making ammonia compatible with current engine technology, with minimal modifications required. This study examines the impact of various discharge, flow, and composition parameters on ammonia conversion into hydrogen using a new well-stirred homogeneous plasma reactor. Gas chromatography was used to measure hydrogen and oxygen, while ICCD imaging evaluated plasma homogeneity. Initial mixture composition significantly influences the response to plasma conditions. Relative to the initial ammonia composition, the conversion of pure ammonia yields a lower hydrogen percentage when compared to air-diluted mixtures. Introducing air changes the relationship between pulsed energy deposition and hydrogen production, resulting in a more substantial increase in conversion. Efficiency calculations demonstrate that high ammonia content and high pulse frequencies improve yields, while longer residence times in the reactor result in higher temperatures, also increasing yields. These findings provide insights into the underlying mechanisms of ammonia cracking and reforming in a discharge, and will serve to promote further investigation into plasma reforming strategies.

Особенности инициирования подвижным источником энергии реакций в плоском слое, расположенном на подложке

In the conditions of the surface treatment of materials and coating application using mixtures of powders (metals, metals and nonmetals, metals and oxides) capable of chemical interactions, problems similar to those of solid-phase combustion theory arise. Currently available publications, which confirm the fact of the reactions, are limited to the analysis of the obtained structures, mechanical properties and the statement of the presence of certain compounds and phases. We present the reduced models for the synthesis of composites on a planar substrate allowing us to analyze qualitative effects. The first model is one-dimensional with a total reaction. The second model corresponds to the synthesis of a matrix-inclusion-type composite. The process is assumed to be driven by a moving heat source. Both models take into account the properties of the substrate. The transition to dimensionless variables reveals both the parameters characteristic of macrokinetics and the parameters typical for modern material synthesis technologies. The numerical solution shows that in the presence of a mobile heat source the reaction zone is sufficiently wide, and the temperature dynamics in general is dissimilar to that of combustion processes. It is shown that there is a parameter region in which partial transformation is observed. Two characteristics of the synthesis process have been determined - the time of the reaction initiation and the time of half-transformation (for a sample of finite size). Taking into account detailed kinetics, similar studies allow us to predict the qualitative composition of synthesis products when changing the conditions and initial composition of powder mixtures.

TiB2 effects on the AlMgB14–TiB2 ceramics structure and properties

This paper studied titanium diboride (TiB2) effects on the structure and properties of AlMgB14 ceramics. AlMgB14–TiB2 samples with 30 wt% and 50 wt% TiB2 were obtained by the self-propagating high-temperature synthesis. The addition of 30 wt% TiB2 did not significantly change the phase composition of the AlMgB14 ceramics, which remained comparable with the initial powder mixture composition. However, increasing the TiB2 amount to 50 wt% resulted in the MgAl2O4 spinel phase appearance. The addition of TiB2 significantly increased the microhardness of AlMgB14 from 7 GPa to 19.9 GPa, compared to the initial material, and also increased its flexural strength to 314 MPa.

A novel diffusion flux modeling for laminar premixed flame simulation with OpenFOAM

In this study, we developed a mass diffusion coefficient model for premixed combustion to reduce the computational time, in mixture-averaged diffusivities to serve as a microcomputer resource. In the development, a preliminary theory was derived to construct the associated variables and corrected using a benchmark model as the mixture-averaged model based on Chapman–Enskog binary diffusion. In the validation, the calculation results obtained using the proposed model with a benchmark case, regardless of thermal diffusion and for several fuels at various pressures, temperatures, and initial mixture compositions, showed good agreement. Validation was also performed with the two-dimensional premixed and partially premixed combustion models by implementing the novel diffusion coefficient model in OpenFOAM software. The OpenFOAM solver results were in good agreement with the experimental results. This solver showed good simulation performance at both micro and macro scales. In addition, the processing time was reduced by approximately 70% in all the simulated premixed flame models. Based on these findings, we conclude that the developed model allows researchers to work with more complex premixed combustion modeling with less computational time.

Characteristic time scale as optimal input in Machine Learning algorithms: Homogeneous autoignition

Considering temporally evolving processes, the search for optimal input selection in Machine Learning (ML) algorithms is extended here beyond (i) the readily available independent variables defining the process and (ii) the dependent variables suggested by feature extraction methods, by considering the time scale that characterizes the process. The analysis is based on the process of homogeneous autoignition, which is fully determined by the initial temperature T(0) and pressure p(0) of the mixture and the equivalence ratio ϕ that specifies the initial mixture composition. The aim is to seek the optimal input for the prediction of the time at which the mixture ignites. The Multilayer Perceptron (MLP) and Principal Component Analysis (PCA) algorithms are employed for prediction and feature extraction, respectively. It is demonstrated that the time scale that characterizes the initiation of the process τe(0), provides much better accuracy as input to MLP than any pair of the three independent parameters T(0), p(0) and ϕ or their two principal components. Indicatively, it is shown that using τe(0) as input results in a coefficient of determination R2 in the range of 0.953 to 0.982, while the maximum value of R2 when using the independent parameters or principal components is 0.660. The physical grounds, on which the success of τe(0) is based, are discussed. The results suggest the need for further research in order to develop selection methodologies of optimal inputs among those that characterize the process.

A Screening Approach to Assess the Impact of Various Commercial Sources of Crude Marine λ-Carrageenan on the Production of Oligosaccharides with Anti-heparanase and Anti-migratory Activities.

Oligosaccharides derived from λ-carrageenan (λ-COs) are gaining interest in the cancer field. They have been recently reported to regulate heparanase (HPSE) activity, a protumor enzyme involved in cancer cell migration and invasion, making them very promising molecules for new therapeutic applications. However, one of the specific features of commercial λ-carrageenan (λ-CAR) is that they are heterogeneous mixtures of different CAR families, and are named according to the thickening-purpose final-product viscosity which does not reflect the real composition. Consequently, this can limit their use in a clinical applications. To address this issue, six commercial λ-CARs were compared and differences in their physiochemical properties were analyzed and shown. Then, a H2O2-assisted depolymerization was applied to each commercial source, and number- and weight-averaged molar masses (Mn and Mw) and sulfation degree (DS) of the λ-COs produced over time were determined. By adjusting the depolymerization time for each product, almost comparable λ-CO formulations could be obtained in terms of molar masses and DS, which ranged within previously reported values suitable for antitumor properties. However, when the anti-HPSE activity of these new λ-COs was screened, small changes that could not be attributed only to their small length or DS changes between them were found, suggesting a role of other features, such as differences in the initial mixture composition. Further structural MS and NMR analysis revealed qualitative and semi-quantitative differences between the molecular species, especially in the proportion of the anti-HPSE λ-type, other CARs types and adjuvants, and it also showed that H2O2-based hydrolysis induced sugar degradation. Finally, when the effects of λ-COs were assessed in an in vitro migration cell-based model, they seemed more related to the proportion of other CAR types in the formulation than to their λ-type-dependent anti-HPSE activity.

Self-propagating high-temperature synthesis of MAX phases in Ti–Zr–Al–C system (C:P15)

The paper reports the results of the Self-propagating High-temperature Synthesis (SHS) in ternary Ti–Al–C and quaternary 2xTi - 2(1-x)Zr − Al – C (x = 0.5–0.9) systems, combusted in argon and hydrogen environments. The effect of the initial mixture composition on the microstructure, phase composition, and crystallographic parameters of the synthesized compounds was investigated. Rietveld analysis of X-ray diffraction patterns was used to calculate the lattice parameters and quantitative phase composition. The combustion of the Ti–Al–C system resulted in the formation of Ti2AlC and Ti3AlC2 MAX phases (85–89%), as well as TiCx phase (11–15%). The combustion of Ti–Zr–Al–C system depending on the Ti/Zr ratio and Al and C contents, along with the main Ti2AlC, Ti3AlC2, Zr2AlC MAX phases, the FCC carbides of transition metals also formed. The highest percentage (91%) of MAX phases was produced by SHS of the 0.9Ti+0.1Zr+0.5Al+0.5C mixture in the argon atmosphere.

Novel Pathway for the Combustion Synthesis and Consolidation of Boron Carbide.

A novel pathway for the magnesiothermic reduction of boron oxide and magnesium dodecaboride (MgB12) in the presence of carbon by a self-propagating high-temperature synthesis method was proposed that was aimed at the direct preparation of boron carbide nanopowder. The combined utilization of two boron sources, boron oxide and MgB12, allowed tailoring the overall caloric effect of the process, increasing the yield of the target product and lessening the laborious leaching process. In addition, it is an alternative way to utilize magnesium borides, which are inevitable side products at boron production. Multivariate thermodynamic calculations performed in the B2O3-MgB12-Mg-C system allowed estimating equilibrium compositions of the products and deducing the optimum composition of the initial mixture for obtaining B4C. For the latter, the adiabatic temperature (Tad) is 2100 °C, which is theoretically enough for the implementation of the self-propagating reaction. The combustion reaction was shown to be extremely sensitive to the initial mixture composition, external pressure, as well as sample diameter (heat losses). It proceeds in self-oscillatory mode and leads to the product of a layered macrostructure. The combustion product was then consolidated by the spark plasma sintering technique at different conditions. Vickers microhardness was measured, and the wear erosion behavior was examined. The variation in lattice parameters of boron carbide reflected the influence of synthesis, sintering and erosion conditions on the ordering/disordering of the boron carbide structure.

Ion Current Simulation Model Design for a Spark-Ignited Engine

The use of ion current signals generated during the combustion process of mixed gas as a function of initial mixture composition, temperature and pressure to detect cylinder combustion states is the most recent approach in the design, development, and optimisation of automotive engine combustion control. This paper aims to design predictive identification and computationally fast and accurate ion current models for obtaining combustion information in the engine cylinder in real time. To build a more comprehensive ion current calculation model, the effect of the flame ionisation process, the geometry of the spark plugs, and the combustion pressure and temperature are considered in the new building ion current model. The simulation ion current waveform, which has a double-peak structure, is in good agreement with the experiment values; thus, the ion current model has the potential to be used for real-time control and optimisation of engine cylinder combustion.

Impact of electronic excitation on the state-to-state vibrational-chemical CO kinetics

Dissociation of carbon monoxide in shock heated flows is studied with emphasis to the phenomenon of dissociation induction. Different kinetic schemes are implemented, both neglecting and including electronic excitation; various vibrational and electronic state-resolved models of dissociation rate coefficients are assessed. Vibrational-electronic relaxation coupled to dissociation behind the shock front is simulated in the frame of the state-to-state approach for several test cases with varying initial pressure, temperature, mixture composition and shock velocity. It is found that dissociation delay may appear regardless taking into account electronic excitation; the incubation time is mainly governed by mixture composition and initial pressure. Electronic excitation noticeably influences the overall dissociation rate. Recommendations for using specific dissociation models are given for different test cases.

Model-based compositional predictions for a differential scanning calorimetry/thermogravimetric analysis-mass spectrometry system used for heat of vaporization measurements

A Differential Scanning Calorimetry/Thermogravimetric Analysis (DSC/TGA) procedure for determination of Heat of Vaporization (HOV) of fuel and surrogate fuel mixtures has been previously utilized for evaluation of oxygenate impacts on spark ignition fuels. This analysis has been further leveraged with mass spectrometry (MS) to elucidate vapor phase compositional changes during evaporation. In this article we focus on a simple system of three compounds (ethanol, n-hexane, and n-octane) to provide a model-based understanding of the evaporation process under these experimental conditions. An Aspen Plus model was set up to provide liquid and vapor phase concentration predictions during mixture evaporation using the initial mixture composition, and measured temperature and mass loss profiles from DSC/TGA experiments. Agreements between the trends of the MS ion count profiles and model composition predictions provide a degree of validation of this modeling approach that can allow the interpretation and extrapolation of DSC/TGA measurements for more complex fuel mixtures.

Механохимический синтез пористых кремнийоксиуглеродных композитов

The work is devoted to investigation of the process of mechanochemical synthesis of porous silicon oxycarbide composites. The synthesis was carried out by mechanical treatment of several mixtures of activated carbon and white soot with different mass ratios. Samples were investigated using such methods as X-ray diffraction, infrared spectroscopy, low-temperature nitrogen adsorption/desorption and potentiometric titration. Synchronous thermal analysis including thermogravimetric analysis and differential scanning calorimetry was performed. The results of X-ray diffraction analysis showed that no new phases were formed in the process of mechanochemical synthesis, and the structure of composites obtained can be characterized as highly amorphous. The possibility of activated carbon and white soot to be chemically bonded with the formation of silicon oxycarbides, which act as a binder in the composite structure, during intensive supply of mechanical energy to raw materials was proved. Thermal stability of silicon oxycarbides formed and the amount of free carbon that was not bonded with silicon dioxide were estimated by synchronous thermal analysis. It was established that the initial mixture composition significantly affects the surface chemistry of composites synthesized, which is expressed by a change in concentration of different surface functional groups. A possible mechanism of solid phase interaction between activated carbon and white soot resulting in the formation of Si–O–C bonds was proposed. Investigation of porous structure of composite materials obtained showed that the specific surface area and pore volume become lower with an increase in white soot concentration in the initial mixture. It is possible to adjust the porous structure of composites by changing the activated carbon to white soot mass ratio.

Phase Separation of an Evaporating Ternary Solution in a Hele-Shaw Cell.

In the present work, we investigate the dynamic phenomena induced by solvent evaporation from ternary solutions confined in a Hele-Shaw cell. The model solutions consist of ethanol, water, and oil, and with the decrease in ethanol concentration by selective evaporation, they may undergo microdroplet formation via the ouzo effect or macroscopic liquid–liquid phase separation. We varied the initial concentration of the three components of the solutions. For all ternary solutions, evaporation of the good solvent ethanol from the gas–liquid interface, aligned with one side of the cell, leads to a Marangoni instability at the early stage of the evaporation process. The presence of the Marangoni instability is in agreement with our recent predictions based on linear stability analysis of binary systems. However, the location and onset of subsequent microdroplet formation and phase separation are the result of the interplay between the Marangoni instability and the initial composition of the ternary mixtures. We classified the ternary solutions into different groups according to the initial concentration of oil. For each group, based on the ternary diagram of the mixture, we offer a rationale for the way phase separation takes place and discuss how the instability influences droplet nucleation. Our work helps us to understand under what conditions and where droplet nucleation can take place when advection is present during phase separation inside a microfluidic device.

Reaction of Chalcones with Cellular Thiols. The Effect of the 4-Substitution of Chalcones and Protonation State of the Thiols on the Addition Process. Diastereoselective Thiol Addition.

Several biological effects of chalcones have been reported to be associated with their thiol reactivity. In vivo, the reactions can result in the formation of small-molecule or protein thiol adducts. Both types of reactions can play a role in the biological effects of this class of compounds. Progress of the reaction of 4-methyl- and 4-methoxychalcone with glutathione and N-acetylcysteine was studied by the HPLC-UV-VIS method. The reactions were conducted under three different pH conditions. HPLC-MS measurements confirmed the structure of the formed adducts. The chalcones reacted with both thiols under all incubation conditions. The initial rate and composition of the equilibrium mixtures depended on the ratio of the deprotonated form of the thiols. In the reaction of 4-methoxychalcone with N-acetylcysteine under strongly basic conditions, transformation of the kinetic adduct into the thermodynamically more stable one was observed. Addition of S-protonated N-acetylcysteine onto the polar double bonds of the chalcones showed different degrees of diastereoselectivity. Both chalcones showed a Michael-type addition reaction with the ionized and non-ionized forms of the investigated thiols. The initial reactivity of the chalcones and the equilibrium composition of the incubates showed a positive correlation with the degree of ionization of the thiols. Conversions showed systematic differences under each set of conditions. The observed differences can hint at the difference in reported biological actions of 4-methyl- and 4-methoxy-substituted chalcones.

Silicon carbide obtaining with DC arc-discharge plasma: synthesis, product characterization and purification

The paper presents the results of experimental studies on the silicon carbide powder synthesis from charcoal and silicon in plasma of DC low-voltage arc discharge in ambient air. The observed dependencies of the initial mixture composition, arc discharge duration and treatment cycles on the phase composition of synthesized products allow fabrication of the powdery product composed of two phases: graphite and cubic phase of silicon carbide. The powdery product contains crystals that correspond to the morphology of biomorphic wood-derived silicon carbide. The temperature range suitable for synthesis of powdery product with a removal of an excess of free carbon was established by the differential thermal analysis. The synthesis product consists mainly of carbon and silicon, and insignificant amount of impurities contained in the original charcoal. Oxygen is also present in the synthesis product in an amount up to 4.6 at. %, which may indicate the presence of an amorphous silicon oxide layer on the silicon carbide surface. The proposed method finally yielded the silicon carbide based powder with a lattice parameter a = 4.359 Å.

Study of in-tube condensation heat transfer of zeotropic R32/R1234ze(E) mixture refrigerants

Despite of its widespread use in household HVAC&R systems, R410A is considered to be phased down because of its high global warming potential (GWP) (100-year GWP = 2088). Research efforts are going on in search of an alternative of R410A, which will have a much lower GWP with a comparable heat transfer characteristic. This work presents the analysis of heat transfer characteristics along with a prediction method during condensation of potentially low-GWP zeotropic mixtures of R32/R1234ze (E) as a replacement of R410A. At three different initial mass concentrations (0.25/0.75, 0.45/0.55, and 0.75/0.25) of R32/R1234ze(E), the heat transfer data were taken at saturation temperatures (30, 40, and 45°C) under a wide range of mass fluxes (100-500 kg m−2s−1) and vapor quality (0.9-0.1) inside a smooth horizontal tube. The effects of mass flux, saturation temperature, and initial mixture compositions on heat transfer coefficient (HTC) were clearly stated. Results show that mixtures of R32/R1234ze (E) exhibit lower HTCs than those of their pure forms due to the presence of a mass transfer resistance during condensation of the mixtures. The current investigation found that the mass transfer during the vapor-liquid phase change of the zeotropic mixture is largely governed by two of its key features: temperature glide and initial mass composition. Considering that, a generalized correlation of condensation HTC has been developed introducing a new dimensionless parameter which includes all the aspects to count the mass transfer resistance. The new correlation shows a better prediction than the previous models with a mean deviation of 8.5%.

OSDA-free hydrothermal conversion of kenyaite into zeolite beta in the presence of seed crystals

Zeolite beta with high crystallinity has been successfully synthesized by using kenyaite conversion method with seed crystals under hydrothermal treatment at 125 °C for 36 h. The OSDA-free synthesis of zeolite beta could be obtained from the mixture composition of 0.96 NaOH: SiO2: 0.0167 Al2O3: 180 H2O by adding 25 wt % seeds. To study the crystallization behaviours and the medium-range structure changes during the conversion process, the prepared zeolite beta was characterized by powder X-ray diffraction, field-emission scanning electron microscope, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, solid-state 27Al MAS and 29Si MAS NMR spectroscopy. The growth of zeolite beta happened on the surface of kenyaite. The five-membered rings and six-membered rings in kenyaite were partly preserved and the four-membered rings were formed by the connection of five-membered rings during the crystallization process. Meanwhile, the effects of reaction time, the initial mixture composition, the quantity of beta seed crystals and temperature in the synthesis were investigated. The as-synthesized zeolite beta, with relatively high thermal stability, exhibits good catalytic performance in the cyclohexanol dehydration reaction system.

Chemical foot print of precomposted dung material of Elephus maximus and Bos taurus through GC–MS profile

The growth and reproductive potential of composting earthworm is influenced by the chemical composition of initial feed mixture. Thus the GC-MS technique is used to determine the biochemical foot prints of the vermibed substrate before composting process. The present study conducted to analyze the chemical composition of precomposted animal dung material of Elephus maximus and Bos taurus by GC-MS analysis. The dung materials were precomposted up to 14 days and used for the analysis. The GC-MS spectrogram of Elephus maximus and Bos taurus showed 20 and 15 different compounds respectively. Predominant levels of esters were observed in elephant dung, which were dominated by the esterified polyunsaturated fatty acids with maximum peak area for elaidinsaeure methyl ester (26.6%). In cow dung the maximum peak area was obtained for 1-Hydroxy-1-methyl) −2-Methyl tetrahydro −2 furanyl] − 4, 4, 14-Trimethylandrost- 9 (11) – ene −3, 6, 16 (17%) and alcohol were the dominant functional group followed by carboxylic acids and esters. Thus the results indicated that the presence of higher percentage of esterified poly unsaturated fatty acids in elephant dung reflects its higher quality suitable for vermicomposting, since the dietary unsaturated fatty acids have the positive impacts on the reproduction of earthworm by enhancing the functionality in sperm production.

Models validation and code profiling in state-to-state simulations of shock heated air flows

The objective of this study is to examine various combinations of vibration-chemical coupling models in high-temperature air and oxygen flows behind shock waves. Simulations are carried out in the frame of the state-to-state approach for detailed vibrational and chemical kinetics in the Euler approximation. Great variety of state-resolved models for the rate coefficients of vibrational energy transitions and chemical reactions are assessed and validated against experimental data; among them are first-order perturbation (SSH) and forced harmonic oscillator (FHO) models; well-known Marrone–Treanor dissociation model with parameters either obtained empirically or by fitting quasiclassical trajectory calculations; new models for state-specific Zeldovich reactions. To validate the models, the results of numerical flow simulations are compared with experimental investigations in a wide range of initial mixture compositions and shock wave velocities. Among numerous model variants, a few models providing the best agreement with the experimental data on the vibrational temperature in oxygen flows and measured NO radiation in air flows are recommended for different sets of free stream conditions. The impact of NO excited states produced in Zeldovich reactions is evaluated; it is shown that neglecting the vibrational excitation of NO molecules may lead to significantly underpredicted maximum of NO number density. In the framework of the code performance study, Matlab and Fortran implementations were compared, the most significant bottlenecks procedures were identified by profiling analysis, and remarkable speed-up was achieved by code optimisation.