Postfunctionalization of poly(propargyl methacrylate) using copper catalyzed 1,3‐dipolar Huisgen cycloaddition: An easy route to electro‐optic materials

A one‐pot synthetic route based on copper‐catalyzed Huisgen reaction has been developed to functionalize a methacrylate propargylic polymer with azido‐substituted moieties. This procedure was used for the preparation of electro‐optic materials containing well‐known Disperse Red One (DR1) chromophores along with bulky adamantyl moieties (Adam). The postfunctionalization of the propargylic polymer was successfully achieved using different molar ratios of DR1/Adam. These novel polymers exhibit high glass transition temperature owing to the rigid structure of adamantyl units. Moreover, the second harmonic generation measurements demonstrated the effectiveness of adamantyl groups to act as insulating shield limiting thus the electrostatic interactions between chromophores. Indeed, higher optimal chromophore concentration (50 mol %) than in conventional DR1‐containing polymers (30 mol %) allowed us to increase the d₃₃ coefficient up to 92 pm/V. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5652–5660, 2009     

Mixing of atmospheric gas concentrations

Atmospheric gas concentrations were measured at 1 s intervals in the upper troposphere during a flight through and near the anvil of a storm. The observed very high correlations between the concentrations of CO and CH4 are interpreted as arising from the mixing of two distinct air masses with differing concentrations of each species, and is due to the nearly identical diffusivities of CO and CH4 in air. We find that the correlations depend on the period over which each concentration measurement was made. Correlations in measurements made over short periods decay with time, while correlations over larger scales remain high. We interpret this using a simple mixing model.     

Multipole moments and spin-dependent sum rules and their applications to f72 and s-d shell nuclei

Matrix elements of multipole operators, defined separately for neutrons and protons, are related to spin-dependent sums of spectroscopic factors. A clarification of their relation to the matrix elements of single-particle operators enables the overlap representation to be formally extended to a stripping form for J ≠ 0 operators. Multipole moments obtained from $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ transfer data are found to be dominated by the quadrupole moments when the final nucleus is odd-odd.A previously found (2J + 1) rule for spectroscopic sums, which arises when the odd-J multipole moments vanish, is shown to lead to approximate sum rules which apply separately to stripping and pickup data. The sum rules are generally well satisfied for transfers leading to odd-odd nuclei in the s-d shell.     

Elastic and inelastic scattering of polarized protons from even n=82 nuclei near isobaric analog resonances

Excitation curves for the elastic and the inelastic scattering of polarized protons on the target nuclei ¹³⁸Ba, ¹⁴⁰Ce, ¹⁴²Nd and ¹⁴⁴Sm have been measured in the energy region of prominent isobaric analog resonances. A detailed analysis of the data is presented. Definite J^π assignments are given for a number of parent analog states. Spectroscopic factors and amplitudes for configurations with the core in the ground state or in the 2₁⁺ excited state are derived from the elastic and inelastic proton decay amplitudes. They show consistency with sum rules including orthogonality conditions. Different methods for the-calculation of single particle decay widths have been applied. The qualitative agreement with present unified model calculations is remarkable; an overestimattion of the weak coupling structure, however, becomes apparent.     

Variation of the Milnor Fibration in Pencils of Hypersurface Singularities

Let = (f, g):(Cⁿ_{+ 1},0) (C₂, 0) be a pair of holomorphic germswith no blowing up in codimension 0. (Two examples are the following: defines an isolated complete intersection singularity; g =l^N where is a generic linear form with respect to f and N>0.) We study how the Milnor fibrations of the germs _(:ß)= g-ß f are related to each other when (:ß)varies in P¹. More precisely, we construct isotopic subfibrationsor subfibres of the Milnor fibrations of any two such germs.The proofs are based on the precise study of the subdiscs ofcomplex lines meeting a fixed complex plane curve germ transversally,generalizing Lê's work on the Cerf diagram. 2000 MathematicalSubject Classification: 32S55, 32S15, 32S30.     

Pt||ZrO2 nanoelectrode array synthesized through the sol–gel process: evaluation of their sensing capability

Homogeneous, circular Pt||ZrO₂ nanoelectrodes have been synthesized through the sol–gel chemistry and the dip-coating process. These nanoelectrode arrays have been evaluated as a platform for electropolymerization of phenol, as model. We have shown that the microstructure of the polymer depends on the confined environment of the electrode and on the position of the –OH group of the monomer. Additionally, these nanoelectrodes have been tested as an electrochemical sensor for dihydroxybenzene isomers in aqueous medium. These Pt||ZrO ₂ nanoelectrodes exhibit a detection limit of 2?×?10^?7?M for resorcinol and 1?×?10^?6?M for catechol.     

On the use of Gegenbauer reconstructions for shock wave propagation modeling

In therapeutic ultrasound, the presence of shock waves can be significant due to the use of high intensity beams, as well as due to shock formation during inertial cavitation. Although modeling of such strongly nonlinear waves can be carried out using spectral methods, such calculations are typically considered impractical, since accurate calculations often require hundreds or even thousands of harmonics to be considered, leading to prohibitive computational times. Instead, time-domain algorithms which generally utilize Godunov-type finite-difference schemes are commonly used. Although these time domain methods can accurately model steep shock wave fronts, unlike spectral methods they are inherently unsuitable for modeling realistic tissue dispersion relations. Motivated by the need for a more general model, the use of Gegenbauer reconstructions as a postprocess tool to resolve the band-limitations of the spectral methods are investigated. The present work focuses on eliminating the Gibbs phenomenon when representing a steep wave front using a limited number of harmonics. Both plane wave and axisymmetric 2D transducer problems will be presented to characterize the proposed method.     

The effects of high energy electron beam irradiation on the thermal and structural properties of low density polyethylene

Radiation is currently being exploited to modify polyethylene in order to improve properties for various applications such as hip replacements. This paper thoroughly examines the effects of high energy electron beam irradiation (10 MeV) on low density polyethylene (LDPE) material. ASTM (American Society for Testing and Materials) testing specimens were manufactured from LDPE and subjected to a broad range of doses ranging between 25 and 400 kGy at room temperature in an air atmosphere. Extensive characterisation techniques such as modulated differential scanning calorimetry (MDSC) and the Fourier transform infrared spectroscopy (FTIR) were conducted on the non-irradiated and irradiated samples. While considering the semicrystalline nature of LDPE during the MDSC experiment, the melting temperature (T_m) and the temperature crystallinity (T_c) were calculated. This revealed that the T_m and the T_c decreased in temperature as the irradiation dose increased. The FTIR analysis was implemented to evaluate the presence of polar species such as carbonyl groups and trans-vinylene double bond groups. The IR spectra illustrated that the concentration of characteristic bands for trans-vinylene bonds increased with increasing radiation dose indicating the formation of carbonyl bond groups. Furthermore, the results demonstrated an occurrence of oxidative degradation due to the formation of carbonyl groups at 1718 cm^?1.     

Quartz microfluidic chip for tumour cell identification by Raman spectroscopy in combination with optical traps

Three important technical innovations are reported here towards Raman-activated cell sorting. Firstly, a microfluidic chip made of quartz is introduced which integrates injection of single cells, trapping by laser fibres and sorting of cells. Secondly, a chip holder was designed to provide simple, accurate and stable adjustment of chips, microfluidic connections and the trapping laser fibres. The new setup enables to the collection of Raman spectra of single cells at 785 nm excitation with 10 s exposure time. Lastly, a new type of modelling the various background contributions is described, improving Raman-based cell identification by the classification algorithm linear discriminant analysis. Mean sensitivity and specificity determined by iterated 10-fold cross validation were 96 and 99 %, respectively, for the distinction of leucocytes extracted from blood, breast cancer cells BT-20 and MCF-7, and leukaemia cells OCI-AML3.