Study of spontaneous fission with EUROGAM

Prompt γ radiation following spontaneous fission has been measured using the EUROGAM 2 array. Using these data and newly developed analysis techniques a number of subjects were studied, which are briefly discussed. One of these subjects, shape transition in A≈100 Sr and Zr nuclei is discussed in more detail. Quadrupole moments were determined for rotational bands in the N=58,59,60,62 and 64 Sr and Zr isotopes. Deformation parameters, which increase from β₂ ≈ 0.1 at N=56 to β₂ ≈ 0.4 at N=64, suggest that in strontium and zirconium isotopes shape change happens gradually between N=56 and N=62 and is probably due to an occupancy of three or more deformation-driving orbitals of h_11/2 parentage.     

Spectral Analysis of Some Distillates from Asphalt Cracking and Evaluation of UTIMAC as Cracking Catalyst

This paper demonstrates the spectral analysis of some distillates obtained from asphalt cracking in the presence of a conventional expensive catalyst, i.e., HZSM‐5, and local cheap and readily available clay, i.e., UTIMAC. Each distillate was fractionated into pentane soluble (PI) and pentane insoluble (PI) fractions based on solubility in n, pentane. Both PS and PI obtained in the case of HZSM‐5 and UTIMAC were analyzed by ¹H‐NMR spectrophotometry using CDCl₃ as dissolving solvent and tetramethylsilane (TMS) as internal standard. It is evident from the profiles that both catalysts caused the generation of some peaks ascribed to methylene and methene configurations in the aliphatic region. Bands corresponding to aromatic configurations were also generated. The results indicate that the cheap local catalyst used has comparable suitability with the conventional expensive catalyst in terms of asphalt cracking.     

Plasma Photocathodes

Plasma wakefield accelerators offer accelerating and focusing electric fields three to four orders of magnitude larger than state-of-the-art radiofrequency cavity-based accelerators. Plasma photocathodes can release ultracold electron populations within such plasma waves and thus open a path toward tunable production of well-defined, compact electron beams with normalized emittance and brightness many orders of magnitude better than state-of-the-art. Such beams will have far-reaching impact for applications such as light sources, but also open up new vistas on high energy and high field physics. This paper reviews the innovation of plasma photocathodes, and reports on the experimental progress, challenges, and future prospects of the approach. Details of the proof-of-concept demonstration of a plasma photocathode in 90° geometry at SLAC FACET within the E-210: Trojan Horse program are described. Using this experience, alongside theoretical and simulation-supported advances, an outlook is given on future realizations of plasma photocathodes such as the upcoming E-310: Trojan Horse-II program at FACET-II with prospects toward excellent witness beam parameter quality, tunability, and stability. Future installations of plasma photocathodes also at compact, hybrid plasma wakefield accelerators, will then boost capacities and open up novel capabilities for experiments at the forefront of interaction of high brightness electron and photon beams.     

On Distance Laplacian Spectra of Certain Finite Groups

Acta Mathematica Sinica, English Series - For a finite group G, the power graph $$\cal{P}(G)$$ is a simple connected graph whose vertex set is the set of elements of G and two distinct vertices x...     

Weighted Cebysev-Ostrowski type inequalities

In account of the famous Cebysev inequality, a rich theory has appeared in the literature. We establish some new weighted Cebysev type integral inequalities. Our proofs are of independent interest and provide new estimates on these types of inequalities.     

Step planar extension of polymer melts using a lubricated channel

A technique to do step planar extension on polymer melts has been developed using a rectangular channel with lubricated walls and the linear motor of the Rheometrics System Four rheometer. Using this method we probe the stress relaxation of two polymer melts, a linear low density polyethylene (LLDPE) and a highly branched low density polyethylene (IUPAC X), and compare the step planar extensional data to step shear data. Since a step planar deformation is theoretically equivalent to a step shear in a rotating frame of reference, we expect that the nonlinear modulus for step planar extension should be equivalent to that for step shear. Although we find the time dependence of the stress relaxation modulus to be the same in both shear and planar extension, the strain dependence is surprisingly different for the two experiments.     

Some rheological properties of lyotropic liquid crystals formed by phosphated polyoxyethylene surfactants,n-hexane and water

Summary Rheological measurements have been carried out using continuous shear viscometry and creep testing on two major mesophases previously found in systems containing phosphated nonyphenol ethoxylate (PNE), phosphated fatty alcohol ethoxylate (PFE), water andn-hexane. Systems containing lamellar liquid crystals exhibited a clockwise (rheopectic) hysteresis loop on the Ferranti-Shirley cone-and-plate viscometer which increased in area with increasing water content. On the other hand, both the hexagonal liquid crystalline phase and an intermediate amorphous gel phase showed an antì-clockwise (thixotropic) hysteresis.Creep tests with an air-bearing viscometer indicated that the majority of the lamellar phase systems tested had a linear visco-elastic behavior which could generally be characterised by one Maxwell unit combined with two Voigt units.The results are discussed in relation to the effects that water produces on the probable structure of the mesomorphic structures, in particular the coiling of the polyoxyethylene chains on the surfactant molecules.

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Zusammenfassung Rheologische Messungen mit den Methoden der kontinuierlichen Scherviskosimetrie und der Kriech-Prüfung wurden an zwei neu gefundenen Haupt-Mesophasen in Systemen von phosphatisiertem Nonylphenol-Äthoxylat (PNE), phosphatisiertem Fettalkohol-Äthoxylat (PFE), Wasser undn-Hexan durchgeführt. Die Systeme mit lamellaren flüssigen Kristallen zeigten im Ferranti-Shirley Kegel-Platte-Viskosimeter eine im Uhrzeigersinne verlaufende (rheopexe) Hysteresis-Schleife, deren Fläche mit zunehmendem Wassergehalt größer wurde. Dagegen zeigten sowohl die hexagonale flüssigkristalline Phase als auch eine intermediäre amorphe Gelphase eine entgegen dem Uhrzeigersinn verlaufende (thixotrope) Hysteresis.Kriech-Versuche mit einem luftgelagerten Viskosimeter ergaben, daß die Mehrzahl der untersuchten lamellaren Systeme ein linear-viskoelastisches Verhalten zeigte, welches durch Kombination von einem Maxwell- und zwei Voigt-Elementen beschrieben werden kann.Die Ergebnisse werden im Hinblick auf die Wirkung des Wassers auf die wahrscheinliche Anordnung der mesomorphen Strukturen diskutiert, insbesondere die Verknäuelung der Polyoxyäthylen-Ketten auf die oberflächenaktiven Moleküle.

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With 4 figures and 2 tables     

Effects due to body-forces and body-couples in the interior of a micropolar elastic half-space—I

A general solution of the equilibrium equations is obtained for a half-space with a fixed boundary and arbitrary but axisymmetric distribution of body forces and body couples in the interior of the half-space. Few particular cases have been investigated in detail. The stresses have been obtained at the boundary and the displacements have been obtained in the interior of the half-space. Numerical results have been displayed graphically.

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Zusammenfassung Eine allgemeine lösung für Gleichgewicht eines Halbraums mit festem Rand und einer beliebigen, aber antisymmetrischen Verteilung von Körperkräften und Körpermomenten im Inneren wird gefunden. Einige Spezialfälle wurden ansführlich erforscht. Die Spannungen am Rand und die Verschiebungen im Inneren des Halbraums wurden erhalten. Numerische Resultate wurden graphisch dargestellt.