Preparative isolation of (+)-beta-eudesmol fromAmyris balsamifera

Summary Optically pure (+)-beta-eudesmol is a possible starting material for the synthesis of several termite defense compounds. A two step procedure for the isolation of gram quantities of (+)-beta-eudesmol from commercially availableAmyris balsamifera oil (syn. West Indian sandalwood oil), containing 8% beta-eudesmol, was developed. Step one consisted of an efficient vacuum distillation of the total oil. Step two was a medium pressure LC separation with an AgNO₃ impregnated silica gel stationary phase. Several other separation procedures failed due to the presence of many closely related sesquiterpene alcohols (75% of the oil).     

The photodetection process under the conditions of an imperfect measurement device

There may be a link between the quantum properties of the vacuum and the parameters describing the properties of light propagation, culminating in a sum over all types of elementary particles existing in Nature weighted only by their squared charges and independent of their masses. The estimate for that sum is of the order of 100.     

Broken symmetries and directed collective energy transport in spatially extended systems

We study the appearance of directed energy current in homogeneous spatially extended systems coupled to a heat bath in the presence of an external ac field E(t). The systems are described by nonlinear field equations. By making use of a symmetry analysis, we predict the right choice of E(t) and obtain directed energy transport for systems with a nonzero topological charge Q. We demonstrate that the symmetry properties of motion of topological solitons (kinks and antikinks) are equivalent to the ones for the energy current. Numerical simulations confirm the predictions of the symmetry analysis and, moreover, show that the directed energy current drastically increases as the dissipation parameter alpha reduces.     

The maximal magnetic susceptibility of polycrystalline nickel

The two maxima in the susceptibility are shown to arise from irreversible displacement of the 182 ° and 90 ° boundaries; the activation energy arising from the internal stresses is found to be proportional to these.     

Shape-preserving interpolation by cubic splines

We consider the problem of shape-preserving interpolation by cubic splines. We propose a unified approach to the derivation of sufficient conditions for the k-monotonicity of splines (the preservation of the sign of any derivative) in interpolation of k-monotone data for k = 0, …, 4.     

Norm estimates for the inverses of matrices of monotone type and totally positive matrices

We give estimates of the infinity norm of the inverses of matrices of monotone type and totally positive matrices.     

A Ru/Zn synergism in extraction of ruthenium by calixarene phosphine oxides

Diesters on the basis of 16-hydroxyisosteviol and dicarboxylic acids, exhibiting anti-tubercular activity, transport Fe(III) through liquid chloroform membrane which models a cell membrane. It is revealed that fluxes and anti-tubercular activity increase, as the length of the chain (spacer) between two ent-beyran skeletons of diesters increases. Computations on the level DFT/PBE explain the dependence of complexes stability on a structure of diterpenoid ligands. The structures of three diesters were established by single crystal X-ray analysis.