Synthesis of Fluorinated Graphene Oxide and its Amphiphobic Properties

The richly functionalized basal plane bonded to polar organic moieties makes graphene oxide (GO) innately hydrophilic. Here, a methodology to synthesize fluorinated graphene oxide by oxidizing the basal plane of fluorinated graphite, allowing for tunable hydrophobicity of GO, is reported. Fluorine exists as tertiary alkyl fluorides covalently bonded to graphitic carbons, and using magic‐angle spinning (MAS) ¹³C NMR as a primary tool chemical structures for the two types of synthesized fluorinated graphene oxides (FGOs) with significantly different fluorine contents are proposed. The low surface energy of the C–F bond drastically affects GO's wetting behavior, leading to amphiphobicity in its highly fluorinated form. Ease of solution processing enables the fabrication of inks that are spray‐painted on various porous/non‐porous substrates. These coatings maintain amphiphobicity for solvents with surface tensions down to 59 dyn/cm, thus bypassing existing lithographic means to create similar surfaces. The approach towards fluorinating GO and fabricating graphene‐based surfaces with tunable wettability opens the path towards unique, accessible, carbon‐based amphiphobic coatings.     

Atmospheric electricity measurements in the upper air over Poona

Atmospheric electricity measurements made during the last decade at Poona using balloon-borne sondes are briefly reviewed. The vertical distribution of potential gradient in the free atmosphere follows theoretical values only during the monsoon months, when the air is comparatively free from dust. During the summer months, the potential gradient is constant above the exchange layer and this is associated with the presence of the deep, dense dust layer that lies over the region and extends to over 10 km. into the atmosphere. The increase with height of the potential gradient above the 10 km. level during winter is shown to be closely related to the presence of the subtropical jet stream, which presumably transports electric charges to the upper levels over Poona.     

Evaluation of the aquifer characteristics of the basaltic terrain of Maharashtra in India

The paper attempts to evaluate the permeability data obtained from 75 aquifer performance tests conducted on open wells tapping the water table aquifer of the basaltic lava flows spread over the three different basins of Maharashtra. The permeability has been computed by Thiem’s formula and the modified Theis non-equilibrium formula. The statistical analysis of the permeability data of the study basins,viz., Bhima, Godavari and Wardha, reveal a decrease in permeability range as one proceeds from the Bhima basin (low rainfall area) through the Godavari basin (assured rainfall area) to the high rainfall area of Wardha basin. The permeability frequency graphs of the three study basins reveal different hydrogeological characteristics for each.     

Quantum chromodynamics corrections to polarised deep-inelastic electron-nucleon scattering

Quantum chromodynamics corrections to orderα _s (the running coupling constant), using the quark-parton approach are calculated for the spin-dependent structure functions in deep-inelastic polarised electron-nucleon scattering. Consequences of these corrections for the Bjorken sum rule and the asymmetry in the case of longitudinally polarised (with respect to the beam) nucleons is discussed which could provide possible tests of quantum chromodynamics. Comparison of our results with the moments of the flavour non-singlet contribution to the structure functions obtained using operator product expansion is also given. An erratum to this article is available at .     

An experimental and modeling study of the autoignition of 3-methylheptane

An experimental and kinetic modeling study of the autoignition of 3-methylheptane, a compound representative of the high molecular weight lightly branched alkanes found in large quantities in conventional and synthetic aviation kerosene and diesel fuels, is reported. Shock tube and rapid compression machine ignition delay time measurements are reported over a wide range of conditions of relevance to combustion engine applications: temperatures from 678 to 1356 K; pressures of 6.5, 10, 20, and 50 atm; and equivalence ratios of 0.5, 1.0, and 2.0. The wide range of temperatures examined provides observation of autoignition in three reactivity regimes, including the negative temperature coefficient (NTC) regime characteristic of paraffinic fuels. Comparisons made between the current ignition delay measurements for 3-methylheptane and previous results for n-octane and 2-methylheptane quantifies the influence of a single methyl substitution and its location on the reactivity of alkanes. It is found that the three C₈ alkane isomers have indistinguishable high-temperature ignition delay but their ignition delay times deviate in the NTC and low-temperature regimes in correlation with their research octane numbers. The experimental results are compared with the predictions of a proposed kinetic model that includes both high- and low-temperature oxidation chemistry. The model mechanistically explains the differences in reactivity for n-octane, 2-methylheptane, and 3-methylheptane in the NTC through the influence of the methyl substitution on the rates of isomerization reactions in the low-temperature chain branching pathway, that ultimately leads to ketohydroperoxide species, and the competition between low-temperature chain branching and the formation of cyclic ethers, in a chain propagating pathway.     

Numerical modelling of ion transport in flames

This paper presents a modelling framework to compute the diffusivity and mobility of ions in flames. The (n, 6, 4) interaction potential is adopted to model collisions between neutral and charged species. All required parameters in the potential are related to the polarizability of the species pair via semi-empirical formulas, which are derived using the most recently published data or best estimates. The resulting framework permits computation of the transport coefficients of any ion found in a hydrocarbon flame. The accuracy of the proposed method is evaluated by comparing its predictions with experimental data on the mobility of selected ions in single-component neutral gases. Based on this analysis, the value of a model constant available in the literature is modified in order to improve the model's predictions. The newly determined ion transport coefficients are used as part of a previously developed numerical approach to compute the distribution of charged species in a freely propagating premixed lean CH₄/O₂ flame. Since a significant scatter of polarizability data exists in the literature, the effects of changes in polarizability on ion transport properties and the spatial distribution of ions in flames are explored. Our analysis shows that changes in polarizability propagate with decreasing effect from binary transport coefficients to species number densities. We conclude that the chosen polarizability value has a limited effect on the ion distribution in freely propagating flames. We expect that the modelling framework proposed here will benefit future efforts in modelling the effect of external voltages on flames. Supplemental data for this article can be accessed at http://dx.doi.org/10.1080/13647830.2015.1090018.     

A note on trans-Sasakian manifolds

In this paper, we obtain some sufficient conditions for a 3-dimensional compact trans-Sasakian manifold of type (α, β) to be homothetic to a Sasakian manifold. A characterization of a 3-dimensional cosymplectic manifold is also obtained.     

Preparation of 4(3H)-quinazolinones from aryldiazonium salt,nitriles and 2-aminobenzoate via a cascade annulation

One-pot synthesis of 3-aryl-4(3H)-quinazolinones has been realized through a cascade annulation. Reaction of aryldiazonium salt with a nitrile provides in situ generation of a reactive nitrilium ion, which is attacked by the amino group of 2-aminobenzoate followed by cyclization to deliver the desired product. This strategy offers a convenient and easy access to a wide range of functionalized quinazolinone.