[en] The theory of hydrophobic effects presented by Pratt and Chandler is generalized to include nonpolar solutes which are distinctly aspherical. The theory is used to study the solvation of simple aspherical hydrocarbon solutes in liquid water. The radial solvation of each component of diatomiclike solutes is studied as a function of their separation, or bond length. From these results it is found that when the bond length is large enough that one water molecule can fit between the apolar pair, the radial solvation of each is the same as that when the bond length approaches infinity. The solvation of the various sites of the homologous series methane, ethane, propane, and n-butane is also studied, and effects of the geometrical structure of the solutes on their solvation is discussed

No abstract available

[en] A new high-resolution powder diffractometer has been constructed for operation on station 8.3 of the Daresbury synchrotron radiation source. This new instrument which is based on the Hart-Parrish design incorporates a channel-cut monochromator, a two circle diffractometer and a long (35.6 cm) diffracted beam collimator. The use of a long beam collimator in conjunction with the low angular dispersion of the synchrotron radiation beam removes the need to consider the reciprocal relationship between angular resolution and diffracted beam intensity inherent in the more common Bragg-Brentano focussing geometry. This configuration also eradicates diffraction pattern errors resulting from sample misalignment. The application of this facility to studies of the structure of long chain hydrocarbons is demonstrated in examples of four recent case studies; 1) the ab-initio indexing of the unit cell of triclinic n-eicosane (C₂₀H₄₂), 2) the phase identification of recrystallized mixtures of n-eicosane and n-docosane (C₂₂H₄₆), 3) the measurement of the long lattice constant of n-triatriacontane (C₃₃H₆₈) and 4) the structural refinement by the Rietveld method of n-octodecane (C₁₈H₃₈). (author)

No abstract available

[en] An efficient multicomponent reaction of nitroalkanes and elemental sulfur with oxiranes was developed with the aid of silver salt. This reaction procedure provides a novel and practical strategy for the rapid assembly of 1,3-oxathiolane skeletons. The reaction exhibited remarkable functional group tolerability and regio-selectivity so that only one regio-isomer formed during the ring opening of oxiranes. Graphical abstract: .

[en] We also reported the synthesis of benzo[a]carbazoles from 2-arylindoles via sequential propargylation, propargyl–allenyl isomerization, and 6π-electrocyclization approach, as shown in Scheme. Various 5-benzyl- and 5-methylbenzo[a]carbazoles have been synthesized; however, 5-unsubstituted benzo[a]carbazoles could not be synthesized by the approach. In order to develop a synthetic method of 5-unsubstituted benzo[a]carbazoles, we decided to examine the reaction of a new synthetic method of benzo[a]carbazoles has been developed from β-(2-phenylindolyl)nitroalkanes via Mn(OAc)_3-mediated cyclization protocol. Various 5-unsubstituted benzo[a]carbazoles could be synthesized, when compared with previous approach to 5-benzylbenzo [a]carbazoles involving 6π-electrocyclization reaction

[en] A maximum in the electron mobility versus density is reported for the polyatomic molecular liquid, 2,2-dimethylbutane. Also, enhanced electron scattering is observed in the gas phase at densities just below the critical density

[en] In this work, an extension is proposed to the standard iterative Boltzmann inversion (IBI) method used to derive coarse-grained potentials. It is shown that the inclusion of target data from multiple states yields a less state-dependent potential, and is thus better suited to simulate systems over a range of thermodynamic states than the standard IBI method. The inclusion of target data from multiple states forces the algorithm to sample regions of potential phase space that match the radial distribution function at multiple state points, thus producing a derived potential that is more representative of the underlying interactions. It is shown that the algorithm is able to converge to the true potential for a system where the underlying potential is known. It is also shown that potentials derived via the proposed method better predict the behavior of n-alkane chains than those derived via the standard IBI method. Additionally, through the examination of alkane monolayers, it is shown that the relative weight given to each state in the fitting procedure can impact bulk system properties, allowing the potentials to be further tuned in order to match the properties of reference atomistic and/or experimental systems

No abstract available

[en] The ability of bacterial species to oxidize alkanes in crude oil in water emulsions was studied. Alkanes in crude oil need specific physiological adaptations to the microorganisms. Synthesis of biosurfactants has been considered as a prerequisite for either specific adhesion mechanisms to large oil drops or emulsification of oil followed by uptake of submicron oil droplets. In this study four bacterial species were tested. Emulsions were prepared by nonionic sorbitan ester and polyoxyethylene ether surfactants. The oxidation rates were measured. Both positive and negative effects of surfactant amendments were observed. The same surfactant affected different bacteria in different ways. The response to the surfactant amendment depended on the physiological state of the bacteria. The results showed that surfactants resulted in decreased cell adhesion to the oil phase for all the bacteria. 19 refs., 3 tabs., 4 figs