The mechanism and kinetics of void formation and growth in particulate filled PE composites

Volume strain measurements were carried out on PE/CaCO3 composites prepared with three different matrix polymers, containing various amounts of filler. The analysis of the debonding process and the various stages of void formation proved that the model developed for the prediction of the initiation of debonding is valid also for the studied PE/CaCO3 composites. Debonding stress is determined by the strength of interfacial adhesion, particle size and the stiffness of the matrix. In thermoplastic matrices usually two competitive processes take place: debonding and the plastic deformation of the polymer. The relative magnitude of the two processes strongly influences the number and size of the voids formed. Because of this competition and due to the wide particle size distribution of commercial fillers, only a certain fraction of the particles initiate the formation of voids. The number of voids formed is inversely proportional to the stiffness of the matrix polymer. In stiff matrices almost the entire amount of filler separates from the matrix under the effect of external load, while less than 30% debond in a PE which has an initial modulus of 0.4 GPa. Further decrease of matrix stiffness may lead to the complete absence of debonding and the composite would deform exclusively by shear yielding. Voids initiated by debonding grow during the further deformation of the composite. The size of the voids also depends on the modulus of the matrix. The rate of volume increase considerably exceeds the value predicted for cross-linked rubbers. At the same deformation and filler content the number of voids is smaller and their size is larger in soft matrices than in polymers with larger inherent modulus

Effect of X-Irradiation on Adenylate Cyclase Activity and Cyclic AMP Content of Primary Human Fibroblasts

Ionizing radiation provokes an increase of the cAMP level in several organs and body fluids. After reviewing the relevant literature we present the results of our own experiments on primary human fibroblasts. X-irradiation at doses of 0.5 and 2.5 Gy in vitro evoked a rapid and reversible increase of adenylate cyclase enzyme activity. A significant increase in cAMP level of these cells was also observed. Adenylate cyclase was usually localized basolaterally on the surface of unirradiated cells, while irradiation resulted in a modification of distribution, i.e., the enzyme activity also appeared in apical localization

Covariance and Fisher information in quantum mechanics

Variance and Fisher information are ingredients of the Cramer-Rao inequality. We regard Fisher information as a Riemannian metric on a quantum statistical manifold and choose monotonicity under coarse graining as the fundamental property of variance and Fisher information. In this approach we show that there is a kind of dual one-to-one correspondence between the candidates of the two concepts. We emphasis that Fisher informations are obtained from relative entropies as contrast functions on the state space and argue that the scalar curvature might be interpreted as an uncertainty density on a statistical manifold.Comment: LATE

Excitation functions of 3He-particle-induced nuclear reactions on 103Rh: Experimental and theoretical investigations

Excitation functions for the 3He-induced reactions on 103Rh as alternative pathway for the production of the medically used 103Pd were studied by the stacked foil technique. Excitation functions of the 103Rh(3α, x) 103Pd, 103,104,104m,105Ag and 100,101,101m,102,102mRh reactions were determined up to 27 MeV by detecting only the characteristic γ-rays obtained from the decay of residual nuclei. The experimental results were compared with the theoretical ones obtained from the EMPIRE-3.2 code and ‎the TENDL nuclear data library. From the measured cross-section data integral production yields were calculated

Particulate Fillers in Thermoplastics

The characteristics of particulate filled thermoplastics are determined by four factors: component properties, composition, structure and interfacial interactions. The most important filler characteristics are particle size, size distribution, specific surface area and particle shape, while the main matrix property is stiffness. Segregation, aggregation and the orientation of anisotropic particles determine structure. Interfacial interactions lead to the formation of a stiff interphase considerably influencing properties. Interactions are changed by surface modification, which must be always system specific and selected according to its goal. Under the effect of external load inhomogeneous stress distribution develops around heterogeneities, which initiate local micromechanical deformation processes determining the macroscopic properties of the composites

Influence of reaction channel on the isomeric cross-section ratio

The influence of reaction channel on the isomeric cross-section ratio was investigated by analysing the experimental data on the reactions Cr-52(p, n)Mn-52m,Mn-g, Cr-52(He-3, t)Mn-52m.g, Fe-54(d, alpha)Mn-52m.g, Fe-54(n, t)Mn-52m.g and Fe-54(He-3, alpha p)Mn-52m.g over the incident particle energy range extending up to 35MeV. The influence is most pronounced when the channels differ widely, for example (p,n) and (He-3, t) processes, i.e. when the reaction mechanisms are different. The nuclear model calculational code EMPIRE-II described the isomeric cross-section ratio rather well in the case of a simple nucleon emission reaction, but not when complex reaction channels were involved

Cross sections for the formation of 69Znm,g and 71Znm,g in neutron induced reactions near their thresholds: Effect of reaction channel on the isomeric cross-section ratio

Excitation functions were measured for the reactions Ge-72(n,alpha)Zn-69(m,g), Ga-69(n,p)Zn-69(m,g), Zn-70(n,2n)Zn-69(m,g), Ge-74(n,alpha)Zn-71(m,g), and Ga-71(n,p)Zn-71(m,g) over the neutron energy range of 6.3-12.4 MeV. Quasimonoenergetic neutrons in this energy range were produced via the H-2(d,n)He-3 reaction using a deuterium gas target at the Julich variable energy compact cyclotron. Use was made of the activation technique in combination with high-resolution HPGe-detector gamma-ray spectroscopy. In a few cases low-level beta(-)counting was also applied. In order to decrease the interfering activities in those cases, either radiochemical separations were performed or isotopically enriched targets were used. For most of the reactions, the present measurements provide the first consistent sets of data near their thresholds. From the available experimental data, isomeric cross-section ratios were determined for the isomeric pair Zn-69(m,g) in (n,alpha), (n,p), and (n,2n) reactions, and for the pair Zn-71(m,g) in (n,alpha) and (n,p) reactions. Nuclear model calculations using the code STAPRE, which employs the Hauser-Feshbach (statistical model) and exciton model (precompound effects) formalisms, were undertaken to describe the formation of both isomeric and ground states of the products. The calculational results on the total (n,alpha), (n,p), and (n,2n) cross sections agree fairly well with the experimental data. The experimental isomeric cross-section ratios, however, are reproduced only approximately by the calculation. For both the isomeric pairs investigated, the isomeric cross-section ratio in the (n,p) reaction is higher than in other reactions