Coulomb excitation of radioactive 20, 21Na

The low-energy structures of the radioactive nuclei ^{20, 21}Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ～ 5×10⁶ ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 ^natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for $ \gamma$ -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For ²¹Na , Coulomb excitation from the 3/2⁺ ground state to the first excited 5/2⁺ state was observed, while for ²⁰Na , Coulomb excitation was observed from the 2⁺ ground state to the first excited 3⁺ and 4⁺ states. For both beams, B ( $ \lambda$ L) values were determined using the 2⁺ $ \rightarrow$ 0⁺ de-excitation in ⁴⁸Ti as a reference. The resulting B(E2) ↓ value for ²¹Na is 137±9 e^2fm^4, while the resulting B( $ \lambda$ L) ↓ values for ²⁰Na are 55±6 e^2fm^4 for the 3⁺ $ \rightarrow$ 2⁺ , 35.7±5.7 e^2 fm^4 for the 4⁺ $ \rightarrow$ 2⁺ , and 0.154±0.030 μ_N^2 for the 4⁺ $ \rightarrow$ 3⁺ transitions. This analysis significantly improves the measurement of the ²¹Na B(E2) value, and provides the first experimental determination of B( $ \lambda$ L) values for the proton dripline nucleus ²⁰Na .-1     

In-line ultrasonic monitoring of semi-solid magnesium die casting process

Ultrasonic velocity and attenuation measurements in AZ91D magnesium (Mg) alloy with dendritic, rosette and globular microstructures were performed at elevated temperatures using a non-contact laser-ultrasonic technique. It was found that the ultrasonic velocity in the globular microstructure and the ultrasonic attenuation in the dendritic microstructure are the highest among the three microstructures. An ultrasonic clad steel buffer rod sensor embedded in the die has been used to monitor the semi-solid die casting process in-line for the AZ91D Mg alloy. This probe monitored the completion of the die filling, the release of the pressure, the opening of the die, part detachment, solidification of the part, the averaged temperature of the die and the part.     

Diffusion des additifs du polyethylene—II: Influence de la structure du polyethylene

In the previous paper, the length (L) of the diffusing molecule was compared with h (as defined by Klein) in a sample of polyethylene. It is interesting to study the variation of h with the crystallinity of the polymer sample, for molecules with lengths less than, greater than or equal to h. The value of h depends upon the density of the polymer; it is possible to define conditions such that the diffusing molecule migrates as a gas or as a long molecule. The polymer crystallinity influences the solubility of the additive but this solubility is affected also by the average molecular weight of the polymer.     

Dispositifs magnetooptiques en couches minces a accord de phase: Utilisation d'une double heteroepitaxie de grenats ferrimagnetiques

The use of a double heteroepitaxy of magnetic garnets to obtain quasi-phasematching in waveguiding experiments is reported here. At a wavelength of 1.152 μm, conversion efficiencies of more than 50% are easily achieved with two appropriate magnetic garnets layers of about 5 μm thickness each deposited on a GGG substrate. This method of quasi-phase-matching is applicable to non-magnetic materials.     

Solubilite des additifs du polyethylene: Methodes et resultats

Some differences have been noticed in papers dealing with the measurement of the solubilities of some additives in polyethylene, depending on the evaluation methods. On the other hand, the results concerning other additives seem not to depend on the measuring methods. This can be confirmed by studying two different additives in the same polyethylene, to represent both situations. An interpretation is then proposed, suggesting that the effect could be due to a modification of the amorphous phase of the polymer.     

Atomic spectroscopy with surface wave plasmas

The use of microwave induced plasmas, particularly of surface wave plasmas, as detectors in atomic emission spectrometry for elemental analysis is reviewed. Surface wave plasmas have been produced at low HF power and used as gas chromatographic detectors. The analytical performances for the detection of non-metals with a Fourier transform spectrometer and a two-channel filter unit are reported. The excitation behavior of non-metals in helium-based mixed gas-plasmas has also be studied. In particular, the effect of power and of nitrogen concentration on the bromine emission has been systematically investigated. A nine-fold improvement of the detection limits for bromine can be obtained in a high power (900 W) helium-nitrogen (0.1-0.2%) plasma.     

New α,ω-diamido and α,ω-diamino mono-and bi-bridged acridine dimers

A novel set of dimers derived from 9-amino acridine was prepared and characterized by¹H and¹³CNMR. These derivatives are bridged at several different positions of the heterocyclic moieties, by the way of ,-diamido or ,-diamino side-chains. Additionally the preparation of some bi-bridged compounds was achieved.

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Neue ,-Dimaido- und ,-Diamino-Mono- und Bi-überbrückte Acridin-Dimere

Zusammenfassung Es wurde eine neue Reihe von Dimeren des 9-Aminoacridins hergestellt und mittels¹H und¹³C-NMR charakterisiert. Diese Derivate sind an verschiedenen Positionen des Heterocyclus mit ,-Diamido- oder ,-Diamino-Seitenketten überbrückt. Zusätzlich wurden auch einige zweifachüberbrückte Verbindungen hergestellt.

     

Preparation of functional hybrid palladium nanoparticles using supercritical fluids: a novel approach to detach the growth and functionalization steps

We report a novel and versatile approach to control separately the growth and functionalization steps in preparing functional nanomaterials. The applicability of this method was demonstrated with the preparation of palladium nanoparticles capped with thiol or stabilized with ionic liquid.     

Degradation,under corona charging,of thermoplastics used in holographic optical commutation and stabilization

The study of the ageing Kinetics under corona discharge of rosin esters used in holographic optical communication devices has shown that free radical inhibitors improve the stability of these matérials. Therefore, new autostabilized thermoplastic products have been synthesized by grafting antioxydant on rosin acids. The stability of materials prepared from these new thermoplastics has proved greatly enhanced.     

Dielectric properties under corona charging of thermoplastics for holographic optical switching

Photothermoplastics are materials which have been proposed for optical switching devices: a grating is recorded by surface deformation of the thermoplastic layer, coated on an organic photoconductive layer used, like in xerography, for an electrostatic image recording material. But first of all an electrical field is applied through a corona charging sequence and obviously dielectric properties of the abietic ester thermoplastic material are of importance. This paper discusses the behaviour of such a layered thermoplastic material in a corona set-up, by measuring the corona current and the surface voltage following thickness and temperature of the sample and charging or discharging times.