Immunoaffinity chromatography for the sample pretreatment of Taxus plant and cell extracts prior to analysis of taxanes by high-performance liquid chromatography

The application of immunoaffinity chromatography for the purification of Taxus plant and cell extracts prior to the HPLC analysis is described. Polyclonal antibodies raised against 10-deacetylbaccatin III (10-DAB III), paclitaxel's main precursor in plant, were characterised by enzymed-linked immunosorbent assay. Immunoglobulins from selected antisera were immobilised on CNBr-activated Sepharose 4B. The immunoaffinity column was used for the purification of plant and plant cell culture extracts prior to their analysis by HPLC. Immunoaffinity chromatography enabled the selective concentration of taxoids and enhanced sample clean-up.     

Bose-Einstein condensation in solid 4He

We present neutron scattering measurements of the atomic momentum distribution n(k) in solid helium under a pressure p=41 bar (molar volume Vm=20.01+/-0.02 cm3/mol) and at temperatures between 80 and 500 mK. The aim is to determine whether there is Bose-Einstein condensation (BEC) below the critical temperature, Tc=200 mK, where a superfluid density has been observed. Assuming BEC appears as a macroscopic occupation of the k=0 state below Tc, we find a condensate fraction of n0=(-0.10+/-1.20)% at T=80 mK and n0=(0.08+/-0.78)% at T=120 mK, consistent with zero. The shape of n(k) also does not change on crossing Tc within measurement precision.     

Quantum momentum distribution and kinetic energy in solid 4He

We present measurements of neutron scattering from solid 4He at high momentum transfer. The solid is held close to the melting line at molar volume 20.87 cm3/mol and temperature T=1.6 K. From the data, we determine the shape of the momentum distribution, n(k), of atoms in the solid and the leading final state contribution to the scattering. We show that n(k) in this highly anharmonic, quantum solid differs significantly from a Gaussian. The n(k) is more sharply peaked with larger occupation of low momentum states than in a Maxwell-Boltzmann distribution, as found in liquid 4He and predicted qualitatively by path integral Monte Carlo calculations. The atomic kinetic energy is =(24.25+/-0.30) K. If n(k) is assumed to be Gaussian, as is usually the practice, a 10% smaller is obtained.     

Toward a formalism of modeling and simulation using model theory

This article proposes a Modeling and Simulation (M&S) formalism using Model Theory. The article departs from the premise that M&S is the science that studies the nature of truth using models and simulations. Truth in models and simulations is relative as they seek to answer specific modeling questions. Consequently, truth in M&S is relative because every model is a purposeful abstraction of reality. We use Model Theory to express the proposed formalism because it is built from the premise that truth is relative. The proposed formalism allows us to: (1) deduce formal definitions and explanations of areas of study in M&S, including conceptual modeling, validity, and interoperability, and (2) gain insight into which tools can be used to semi‐automate validation and interoperation processes. © 2013 Wiley Periodicals, Inc. Complexity 19: 56–63, 2014     

Wavelet analysis of ellipticity,dispersion, and dissipation properties of Rayleigh waves

This paper is devoted to the digital processing of multicomponent seismograms using wavelet analysis. The goal of this processing is to identify Rayleigh surface elastic waves and determine their properties. A new method for calculating the ellipticity parameters of a wave in the form of a time-frequency spectrum is proposed, which offers wide possibilities for filtering seismic signals in order to suppress or extract the Rayleigh components. A model of dispersion and dissipation of elliptic waves written in terms of wavelet spectra of complex (two-component) signals is also proposed. The model is used to formulate a nonlinear minimization problem that allows for a high-accuracy calculation of the group and phase velocities and the attenuation factor for a propagating elliptic Rayleigh wave. All methods considered in the paper are illustrated with the use of test signals.     

Ferrocenyl-terminated redox stars: synthesis and electrostatic effects in mixed-valence stabilization

A family of rigid ferrocenyl-terminated redox stars has been synthesized-by Negishi coupling, including hexa(ferrocenethynyl)benzene complexes, a dodecaferrocenyl star, and stars with extended rigid tethers-and fully characterized. Cyclic voltammetry (CV) studies of the parent complex hexa(ferrocenylethynyl)benzene, 1, show a single wave for the six-electron oxidation of 1 using Nn-Bu(4)PF(6) as the supporting electrolyte on a Pt anode in CH(2)Cl(2), whereas three distinct two-electron reversible CV waves are observed using Nn-Bu(4)BAr(F)(4) (Ar(F) = 3,5-C(6)H(3)-(CF(3))(2,)). The CV of 1,3,5-tris(ferrocenylethynyl)benzene, 11, also shows only one wave for the three-electron transfer with Nn-Bu(4)PF(6) and three one-electron waves using Nn-Bu(4)BAr(F)(4). This confirms the lack of electronic communication between the ferrocenyl groups and a significant electrostatic effect among the oxidized ferrocenyl groups. This effect is not significant between para-ferrocenyl groups in 1,4-bis(ferrocenylethynyl)benzene for which only a single wave is observed even with Nn-Bu(4)BAr(F)(4) as the supporting electrolyte. The para-ferrocenyl substituents are quite independent, which explains that two para-ferrocenyl groups are oxidized at about the same potential in a single CV wave of 1. With the additional steric bulk introduced with a methyl substituent on the ferrocenyl group, however, even the para-methylferrocenyl groups are submitted to a small electrostatic effect splitting the six-electron transfer into six single-electron waves, probably because of the overall steroelectronic constraints. Contrary to 11, 1,3-bis(ferrocenylethynyl)benzene and related complexes with a third, different substituent in the remaining meta position different from a ferrocenylethynyl only show a single two-electron wave using Nn-Bu(4)BAr(F)(4), which is attributed to the transo?d conformation of the ferricinium groups minimizing the electrostatic effect. This shows that, in 11, it is the steric frustration that is responsible for the electrostatic effect, and the same occurs in 1. In several cases, ΔE(p) is much larger than the expected 60 mV value, characterizing a quasi-reversible (i.e., relatively slow) redox process. It is suggested that this slower electron transfer be attributed to conformational rearrangement of the ferrocenyl groups toward the transo?d position in the course of electron transfer. Thus both the thermodynamic and kinetic aspects of the electrostatic factor (isolated from the electronic factor), including the frustration effect, are characterized. The distinction between the electronic communication and through-space electrostatic effect was made possible in all of these complexes in which the absence of wave splitting using a strongly ion-pairing electrolyte shows the absence of significant electronic communication, and was confirmed by the new frustration phenomenon.     

Revisiting parametric multi-terminal problems: Maximum flows, minimum cuts and cut-tree computations

Given an undirected network, the multi-terminal network flows analysis consists in determining the all pairs maximum flow values. In this paper, we consider an undirected network in which some edge capacities are allowed to vary and we analyze the impact of such variations on the all pairs maximum flow values. We first provide an efficient algorithm for the single parametric capacity case, and then propose a generalization to the case of multiple parametric capacities. Moreover, we provide a study on Gomory–Hu cut-tree relationships.     

Dynamics of plasma blobs in a shear flow

The global dynamic of plasma blobs in a shear flow is investigated in a simple magnetized torus using the spatial Fourier harmonics (k-space) framework. Direct experimental evidence of a linear drift in k space of the density fluctuation energy synchronized with blob events is presented. During this drift, an increase of the fluctuation energy and a production of the kinetic energy associated with blobs are observed. The energy source of the blob is analyzed using an advection-dissipation-type equation that includes blob-flow exchange energy, linear drift in k space, nonlinear processes, and viscous dissipations. We show that blobs tap their energy from the dominant ExB vertical background flow during the linear drift stage. The exchange of energy is unidirectional as there is no evidence that blobs return energy to the flow.     

Gold nanoparticles synthesis and stabilization via new "clicked" polyethyleneglycol dendrimers

Gold nanoparticles (AuNPs) are synthesized and stabilized by new "clicked" dendrimers of generations zero to two (G(0)-G(2)) containing tri- and tetra-ethyleneglycol tethers; they are either encapsulated by G(1) (81 tethers) and G(2) (243 tethers) or stabilized without encapsulation by G(0) (27 tethers).