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[en] Liquid–liquid equilibrium data for the n-heptane + phenol + sulfolane system were obtained at 323.15 and 343.15 K under 101.35 kPa pressure. The distribution coefficient (K) and separation factor (S) were calculated to assess the effectiveness of extracting phenol from n-heptane, and the consistency of LLE date were verified by the Othmer–Tobias, Hand as well as Bachman equations. The experimental data were correlated by using NRTL and UNIQUAC models, and the root-mean-square deviation (RMSD) values of both models were below 0.59%, demonstrating the two models were successfully describe the experimental data.
[en] The cracking of heptane (HEP) and the cracking of the binary system of triethylamine/heptane (TEA/HEP) in a continuous tubular reactor at 3.5 MPa are studied, to test the effect of triethylamine on the pyrolysis of heptane under a supercritical condition. It is found that triehtylamine can promote the cracking of heptane under the supercritical condition, and more effective in lower temperatures. The selectivity of ethane, ethylene, propylene, and C4 by pyrolysis of TEA/HEP is notably higher than that by HEP in a low temperature, while the difference of the selectivity is weak when in a high temperature. The kinetic character of the cracking of heptane under the supercritical condition is studied, through which the activation energy and the pre-exponential factor are obtained by pseudo-isothermal method with a quick convergence process
[en] Sodium bicyclic[2,2,1]heptane dicarboxylate (HPN-68) is a highly effective commercial isotactic polypropylene (iPP) nucleating agent. In this paper, isothermal crystallization behaviors of iPP nucleated with HPN-68 were investigated using differential scanning calorimetry (DSC). The calculation model of Lamberti based on the Avrami method was used for obtaining nucleus density from calorimetric crystallization curves recorded under isothermal conditions. A number of growth rate data have been obtained with the Lauritzen and Hoffman equation. General procedures to predict nucleus density by simple DSC measurements were described and applied successfully to iPP. Addition of HPN-68 shortened crystallization half-time (t1/2) and increased the crystallization rate of iPP, eventually the nucleus density of iPP nucleated with HPN-68 for finishing crystallization under higher crystallization temperature was larger than that of virgin iPP, leading to larger crystallization rate and shorter cycle time.
[en] Environmental risk assessment requires models for estimating the bioaccumulation of untested compounds. So far, bioaccumulation models have focused on lipophilic compounds, and only a few have included hydrophilic compounds. Our aim was to extend an existing bioaccumulation model to estimate the oral uptake efficiency of pollutants in mammals for compounds over a wide Kow range with an emphasis on hydrophilic compounds, i.e. compounds in the lower Kow range. Usually, most models use octanol as a single surrogate for the membrane and thus neglect the bilayer structure of the membrane. However, compounds with polar groups can have different affinities for the different membrane regions. Therefore, an existing bioaccumulation model was extended by dividing the diffusion resistance through the membrane into an outer and inner membrane resistance, where the solvents octanol and heptane were used as surrogates for these membrane regions, respectively. The model was calibrated with uptake efficiencies of environmental pollutants measured in different mammals during feeding studies combined with human oral uptake efficiencies of pharmaceuticals. The new model estimated the uptake efficiency of neutral (RMSE = 14.6) and dissociating (RMSE = 19.5) compounds with logKow ranging from − 10 to + 8. The inclusion of the Khw improved uptake estimation for 33% of the hydrophilic compounds (logKow < 0) (r2 = 0.51, RMSE = 22.8) compared with the model based on Kow only (r2 = 0.05, RMSE = 34.9), while hydrophobic compounds (logKow > 0) were estimated equally by both model versions with RMSE = 15.2 (Kow and Khw) and RMSE = 15.7 (Kow only). The model can be used to estimate the oral uptake efficiency for both hydrophilic and hydrophobic compounds. -- Highlights: ► A mechanistic model was developed to estimate oral uptake efficiency. ► Model covers wide logKow range (- 10 to + 8) and several mammalian species. ► Kow and the heptane water partition coefficient Khw were combined. ► Kow and Khw reflect the inner and the outer membrane diffusion resistance. ► Combining Kow and Khw improved uptake estimation for hydrophilic compounds
[en] Highlights: ► Coexistence curves of (dimethyl adipate + n-hexane) (+n-heptane) were measured. ► The critical exponent β are consistent with the 3D-Ising value. ► The asymmetry of the coexistence curves were discussed by complete scaling theory. - Abstract: The liquid–liquid coexistence curves for (dimethyl adipate + n-hexane), (dimethyl adipate + n-heptane) have been measured, from which the critical amplitudes and the critical exponents are deduced. The critical exponent β corresponding to the coexistence curves are consistent with the 3D-Ising value. The experimental results have also been analyzed to determine the critical amplitudes of Wegner-correction terms when β and Δ are fixed at their theoretical values, and to examine the asymmetry of the diameters for the coexistence curves.
[en] The biphenyl/POPOP couple is known for its scintillation properties, but we describe in this letter its use for the discrimination between fast neutrons and gamma rays. More particularly, the influence of the matrix involved in this process is of interest, and for the first time pulse shape discrimination has been observed in non-common solvents such as heptane or ethanol. The discrimination efficiency of our systems is described in terms of figure of merit, angle between neutron and gamma lobes and scintillation performances. (authors)
[en] Several factors affecting plasma oxidation of n-heptane in liquid phase have been investigated. The experimental results show that the temperature of n-heptane is the first major factor affecting formations of heptanol and heptanone, and then oxygen flow and plasma power etc. follow in proper order. Under a typical condition the selectivity of product formation is far superior to that of plasma oxidation in the gas phase
[en] Highlights: ► Surface tension in cavities produced by Ps in alkanes is larger than in flat surface. ► Absolute value of Tolman’s length rises with temperature. ► Ortho-Ps lifetime near the melting point is identical for all liquid alkanes. ► No change of ortho-Ps lifetime at the transition liquid–rotator phase for n > 24. - Abstract: Positron annihilation lifetime spectra were measured in n-alkanes. From the lifetime of ortho-positronium (o-Ps) one can determine the surface tension and Tolman’s length for the cavity produced by positronium in the liquid. This tension is found increased by factor of 1.4 ÷ 1.7 comparing to that of flat surface. The Tolman’s length is temperature dependent; in n-nonadecane it rises from about 0.06 nm at melting point to 0.08 nm at the temperature 100 K higher. Near the melting point the value of surface tension of Ps cavities is practically identical for all alkanes under study, i.e. from heptane C7H16 to pentacontane C50H102