Cholinergic Compounds. XIV.1: Synthesis of cis-2-methyl-5-dimethylaminomethyl-1,3-oxa thiolane methiodide

In order to get information about the role of the oxygen atom in position 1 of dioxolane I and thus about the corresponding binding site of the muscarinic receptor, Elferink and Salemink² have synthesized the sulfur analog II as a cis/trans mixture in a 4:1 or 8:1 ratio, depending upon the synthetic method. This compound proved to be very active as muscarinic agent and might provide useful tool in Structure-Activity Relationship (SAR) studies on muscarinic receptor, if it were available as a pure cis form³.     

Recurrence relations and determinant forms for general polynomial sequences. Application to Genocchi polynomials

In this paper the set of general polynomial sequences is considered. An elementary systematic approach is proposed. In fact a structure of group is given and for every element of this group recurrence relations and determinant forms are derived. Applications of the derived determinant forms are considered. In particular, the general linear interpolation and bounds of the zeros of each polynomial of the sequence are sketched. Finally, as an illustrative example, the shifted (with respect to the degree) Genocchi polynomial sequence is analyzed.     

Free glycerol determination in biodiesel samples using palladium nanoparticles modified glassy carbon electrode associated with solid phase extraction

Journal of Solid State Electrochemistry - In this work, we developed a method for the quantification of free glycerol in biodiesel using electrochemical detection and solid phase extraction (SPE)....     

EPR study of the effect, induced by zidovudine (AZT), on the membrane lipid dynamics in leukemic cell

Zidovudine (AZT) was the first drug approved by the FDA for treatment of HIV infections. To investigate the AZT effects on the physical properties of K562 cell membranes, experiments were performed by measuring an order parameter value in these cells, previously labelled with 16-DSA (16-doxyl-stearic acid) or 5-DSA (5-doxyl-stearic acid). The EPR spectra of the labelled fatty acid were used to detect the alteration in their freedom of motion and to provide indications of membrane fluidity. Two different parameters were calculated from EPR spectra for the 16-DSA and 5-DSA. Preliminary data indicate that, for both the probes used, these parameters were not significantly different in the control cells with respect to the AZT-treated ones. Control measurements, performed to test the sensitivity of the technique using the DMSO agent, showed a significant increase in the K562 membrane fluidity.     

Statistics of particle pair relative velocity in the homogeneous shear flow

Small scale clustering of inertial particles and relative velocity of particle pairs have been fully characterized for statistically steady homogeneous isotropic flows. Depending on the particle Stokes relaxation time, the spatial distribution of the disperse phase results in a multi-scale manifold characterized by local particle concentration and voids and, because of finite inertia, the two nearby particles have high probability to exhibit large relative velocities. Both effects might explain the speed-up of particle collision rate in turbulent flows. Recently it has been shown that the large scale geometry of the flow plays a crucial role in organizing small scale particle clusters. For instance, a mean shear preferentially orients particle patterns. In this case, depending on the Stokes time, anisotropic clustering may occur even in the inertial range of scales where the turbulent fluctuations which drive the particles have already recovered isotropy. Here we consider the statistics of particle pair relative velocity in the homogeneous shear flow, the prototypical flow which manifests anisotropic clustering at small scales. We show that the mean shear, by imprinting anisotropy on the large scale velocity fluctuations, dramatically affects the particle relative velocity distribution even in the range of small scales where the anisotropic mechanisms of turbulent kinetic energy production are sub-dominant with respect to the inertial energy transfer which drives the carrier fluid velocity towards isotropy. We find that the particles’ populations which manifest strong anisotropy in their relative velocities are the same which exhibit small scale clustering. In contrast to any Kolmogorov-like picture of turbulent transport these phenomena may persist even below the smallest dissipative scales where the residual level of anisotropy may eventually blow-up. The observed anisotropy of particle relative velocity and spatial configuration is suggested to influence the directionality of the collision probability, as inferred on the basis of the so-called “ghost collision” model.     

A rhodopsin-like protein in the plasma membrane of Silvetia compressa eggs

Unidirectional blue light directs the rhizoid-thallus axis in the apolar zygote of the brown alga, Silvetia compressa. This effect is mediated by an increase in the intracellular concentration of guanosine 3', 5'-cyclic monophosphate. In this study we show the identification of a rhodopsin-like protein, by means of antibody reaction, in the plasma membrane of Silvetia eggs. This new result suggests a role for opsins in Silvetia photopolarity.     

A Discrete, Deterministic Construction of the Phase in Feynman Paths

In the path-integral formulation of quantum mechanics, the phase factor e ^iS(x〈t〉) is associated with every path x〈t〉. Summing this factor over all paths yields Feynman's propagator as a sum-over-paths. In the original formulation, the complex phase was a mathematical device invoked to extract wave behaviour in a particle framework. In this paper we show that the continuous phase itself can have a discrete origin in time reversal and that the propagator can be drawn by a single deterministic path. ¹On leave from Department of Mathematics, Ryerson University, Toronto, Ontario Canada.     

Asymptotic expansion and extrapolation for Bernstein polynomials with applications

Given a real functionf C ^2k [0,1],k 1 and the corresponding Bernstein polynomials {B _n (f)} _n we derive an asymptotic expansion formula forB _n (f). Then, by applying well-known extrapolation algorithms, we obtain new sequences of polynomials which have a faster convergence thanB _n (f). As a subclass of these sequences we recognize the linear combinations of Bernstein polynomials considered by Butzer, Frentiu, and May [2, 6, 9]. In addition we prove approximation theorems which extend previous results of Butzer and May. Finally we consider some applications to numerical differentiation and quadrature and we perform numerical experiments showing the effectiveness of the considered technique.This work was partially supported by a grant from MURST 40.