New methods for determining the volumetric flow rate in the column and the retention time of the unretained substance in gas chromatography

New methods for calculating the mean volumetric flow rate of the carrier gas and the retention time of the unretained substance in the column under conditions of gas chromatography were proposed. The methods are based on preliminary isothermal calibrations of the flow rate and holdup time for a packed column. A theoretical substantiation of the methods was given. Procedures of plotting calibration dependences for determining the indicated quantities at a desired temperature were described. The calculation results were compared to experimental data obtained by traditional methods. It was demonstrated that the use of calculation methods substantially simplifies the determination of the specific retention volume over a wide temperature range.     

Recent Results on Fast Flow Gas-Phase Partial Oxidation of Lower Alkanes

Recent experimental results and kinetic modeling of fast flow gas-phase oxidation of methane and other lower alkanes to methanol and other oxygenates are discussed,alongside with prospects and possible areas for applications of the processes.     

Kantorovich’s Fixed Point Theorem and Coincidence Point Theorems for Mappings in Vector Metric Spaces

Set-Valued and Variational Analysis - The fixed points and coincidence points of mappings of v-metric spaces, i.e., sets on which a vector metric is defined, are investigated. The values of such a...     

Analysis of Mixtures Containing Unknown Components by Gas Chromatography: Determination of Molecular Mass

New methods are proposed for the gas-chromatographic determination of the molecular masses of unknown components in complex mixtures within one cycle of analysis. The methods are based on the use of complex chromatographic data in the form of linear retention indices of compounds for a column with a nonpolar stationary phase and sensitivity indices of a thermal conductivity detector and a flame ionization detector.     

Effects of the gas medium and heterogeneous factors on the gas-phase oxidative cracking of ethane

The effects of the gas medium and heterogeneous factors on the gas-phase oxidative cracking of dilute ethane mixtures at atmospheric pressure, temperatures of up to 750°C, and an initial reactant ratio of [C₂H₆]₀/[O₂]₀ = 2 have been investigated.     

Experimental study and macrokinetic simulation of the partial gas-phase oxidation of propane

The effect of process parameters on the propane conversion and the composition of oxidation products, particularly the methanol to carbon monoxide ratio, has been studied. A numerical study of the laws governing the partial oxidation of propane has been conducted in terms of a model that approximately describes the macrokinetics of the partial gas-phase oxidation of hydrocarbons in a flow tubular reactor.     

Long-chain alkyl sulfonate micelle fission: a molecular dynamics study

In this study, we investigate micelle fission of long-chain alkyl sulfonate molecules using atomistic scale simulation. GROMACS software code with the united atom force field was applied. 0.5-μs parallel molecular dynamics simulation study was conducted for a surfactant/water system consisting of 192 sodium pentadecyl sulfonate and 40,553 water molecules. The large preassembled micelle was ruptured at Krafft above T?=?323-K temperature, and we track two ellipsoid-like micelles over the course of the production run. To estimate the micelle shape, we determined the principal moments of inertia and the eccentricity, which proved that the micelles have a pronounced prolate spheroid shape, which agrees well with our previous experimental data. The mechanism of micelle fission was explored in detail. The aggregation number, ionization degree, and other parameters obtained from simulation were consistent with existing experimental finding. The determined parameters in addition to simple visual inspection of trajectories revealed monomer-micelle exchange—with the estimated relaxation time τ ₁?=?10^??9s. We assume that the exchange process is conditioned by the unequal size of micelles leading to adjustment of aggregation number.     

Activation of the radical-promoted conversion of light hydrocarbons by the products of a rich methane flame

The feasibility of the production of ethylene and heavier olefins by introducing methane into the products of a rich methane flame is experimentally demonstrated. Such a process is promising for the direct production of ethylene, propylene, and heavier olefins directly from methane, the main component of natural gas.     

Variational Principles and Mean Value Estimates

Journal of Optimization Theory and Applications - In this paper, for a continuous function defined on a closed subset of a Banach space and differentiable on the interior of the domain, the infimum...