Polyfluorobicyclo[4,4,0]decanes. Part I. The fluorination of tetralin over cobalt trifluoride

Fluorination of tetralin over cobalt trifluoride at 250° in a stirred reactor gave the known cis- and trans- perfluorodecalins and two known fluorobicyclo[4,4,0]dec-1(6)-enes. Also obtained were five new heptadecafluorobicyclo[4,4,0]decanes. Dehydrofluorinations of these gave five new hexadecafluorobicyclo[4,4,0]decenes of which one, the 1(2)- isomer, rearranged readily to the 1(6)- isomer.     

Protein association with circular DNA: rate enhancement by nonspecific binding

An analytical solution for the nonspecific-binding-facilitated diffusion-controlled rate of association of a protein with a specific site on a circular DNA is derived. Nonspecific binding is modeled by a short-range attractive surface potential. The protein undergoes diffusion in the bulk solution and in the surface layer. The association rate for a circular DNA is compared to the counterpart for a linear DNA, in which the ends of the surface layer are treated as reflecting. As expected, when the DNA length is long, the shape of the DNA does not affect the association rate. For a shorter length, the association rate for the linear DNA is modestly higher than the circular counterpart. The higher rate of the linear DNA is possibly due to its more open shape, which affords it a higher ability to draw the protein from the bulk to its surface. The analytical solution is verified by Brownian dynamics simulations.     

New insights in the properties of cellulose in phosphoric acid: viscometric study

Measurements of viscosity were carried out using several solutions of cellulose in different concentrations of phosphoric acid at different temperatures. The intrinsic viscosity [η]₀, a measure for the size of a single chain and the Huggins constant k_H, a measure for the interaction between chains were derived.     

Self-gravitating strings and string/black hole correspondence

In a recent essay, we discussed the possibility of using polymer sizing to model the collapse of a single, long excited string to a black hole. In this letter, we apply this idea to bring further support to string/black hole correspondence. In particular, we reproduce Horowitz and Polchinki's results for self-gravitating fundamental strings and speculate on the nature of the quantum degrees of freedom of black holes in string theory.     

Non-parametric identification of the non-homogeneous stress in high strain-rate uni-axial experiments

Stress and strain homogeneity, in tested samples, is a crucial assumption during a dynamic test. Whenever this assumption is true, the conventional recovery of the mean strain and stress is valid. However, when the stress and strain fields in the sample are not homogeneous, more sophisticated treatment must be considered. Inverse problem techniques are then proposed. Nevertheless, they may yield a non-physical result. In this paper, a non-parametric solution to the problem of non-homogeneity in dynamic tests is presented. The stress field is deduced from the displacement field measured via a Digital Speckle Photography (DSP) technique and a force boundary condition.     

Ternary complexes in agarose gels prepared from binary solvents

The thermoreversible gelation of agarose has been investigated in four different aqueous binary solvents: Water/dimethyl sulfoxide, water/N,N-dimethylformamide, water/N-methylformamide, and water/formamide. The phase diagrams have been subsequently established as a function of agarose concentration and solvent composition. These diagrams suggest the formation of ternary complexes agarose/water/cosolvent.     

Preface: Regression methods based on OR techniques and computational aspects in management,economics and finance

Annals of Operations Research -     

1-Soliton solution of the generalized Zakharov equation in plasmas by He’s variational principle

This paper obtains the 1-soliton solution to Zakharov equation with power law and dual-power law nonlinearities. The He’s variational principle is used to carry out the integration of this equation.     

Combined experimental and theoretical investigation of the CO2 adsorption on LaMnO3+y perovskite oxide

The surface interaction of CO₂ with the perovskite-type oxide LaMnO_3+y has been investigated by means of density functional theory calculations and experimental measurements of adsorption isotherms in the temperature range 298-473 K. A (1 0 0) oriented slab of the cubic structure was used for modeling CO₂ adsorption. The reference unit cell contains alternating LaO⁺ layers and layers; one slab is LaO⁺-terminated and the opposite surface is terminated. A Freundlich isotherm fitted the experimental data satisfactorily. Analysis of the isosteric heat revealed an energetically heterogeneous character for the lanthanum manganite oxide surface, mainly due to the degree of heterogeneity of the adsorption center and due to the adsorbate-adsorbate lateral interactions. Considering theoretical calculations and thermodynamical approaches, two types of active sites were found to be responsible for irreversible and reversible adsorption of CO₂ as a function of surface coverage and O₂ treatment. Strong adsorption takes place on the surface containing La cations. The strongest adsorption is associated with surface oxygen vacancies, center. The next strongest adsorption, a flat adaptation of CO₂ molecules with respect to the surface sites, with a strong binding to a surface oxygen, leads to chemisorbed carbonate species. These adsorption modes are chiefly indicative of a high basic character of the lanthanum manganite oxide surface. Several cationic sites formed by lanthanum and manganese cations are able to weakly adsorb CO₂ molecules in perpendicular or bridged forms. The latter adsorption modes suggest a weak acidic character of the manganite adsorbent.