Crazes and fracture in polymers

A review of crazes in glassy thermoplastic polymers is presented with particular emphasis on those aspects of craze properties that influence and control fracture behavior. Both crazes as they normally occur, and crazes at the top of cracks are covered. The occurrence of crazes, their microstructure, the stress distribution within them and the nature of craze fibrils are discussed. Theoretical treatments of the effect of crazes on polymer fracture are reviewed.     

Effect of Logarithmic Mesonic Potential on Nucleon Magnetic Moments and Hedgehog Mass

The logarithmic mesonic potential is proposed for computing some nucleon properties. The logarithmic potential is based on some aspects of QCD. The field equations have been solved in mean-field approximation. Good results are obtained for the nucleon magnetic moment and the hedgehog mass in comparison with the Skyrmion model. In particular, nucleon properties are calculated for sigma and quark masses which are computed recently.     

The Fermi contact nuclear spin-spin coupling in HD

The study of the two-dimensional system of water-like particles is extended to include a second component. Some aspects of very dilute aqueous solutions of simple nonelectrolytes may be simulated in such a system, and in particular the phenomenon of hydrophobic interaction and its dependence on various properties of the solvent is investigated.     

Anisotropic electron mobility in fluorene-PPV and fluorene-MEH-PPV

Polyfluorene copolymers are attractive semiconductor materials, in particular for applications in the organic electronics field. They are versatile to be chemically modified and allow a tuning of the emission to cover the entire visible spectrum. A better understanding of the fundamental aspects of the nature of electronic structure and charge transport properties contribute to the improvement of optoelectronic properties of polymeric materials. Here, we provide a structure–property relationship for models of fluorene-PPV and fluorene-MEH-PPV copolymers, using molecular quantum mechanics modelling. The anisotropy is discussed revisiting Mulliken's transition moment theory. Accordingly, our results show that electron mobility occurs preferentially intrachain for both copolymers. Moreover, the interchain electron mobility has the most propensity to occur via π-stacking interactions.     

Constructive Mathematics and Quantum Physics

We discuss some aspects of quantum logic within Bishop's constructivemathematics. In particular, we present a set of axioms that abstracts theconstructive properties of the lattices of subspaces and projections on a Hilbertspace.     

Ultraviolet and infrared aspects of the axial anomaly II

This is the second part of a brief review of some perturbative aspects of the Adler-Bell-Jackiw axial anomaly. To begin with, we discuss here the derivation of the anomaly based on the imaginary part of the VVA triangle graph and dispersion relations. Within such an approach the infrared properties of the VVA amplitude are substantial. Next we summarize the main results obtained by the present author and co-authors concerning some particular ultraviolet and infrared aspects of the axial anomaly. These results cover a wide variety of topics, ranging from dispersion relations to a systematic analysis of gauge invariant ultraviolet regularizations of the VVA triangle graph. In the latter context, one of the highlights is a reinterpretation of dimensional regularization of the VVA diagram as a continuous superposition of Pauli-Villars cut-offs.     

Characterizing quantum properties of a measurement apparatus: insights from the retrodictive approach

Using the retrodictive approach of quantum physics, we show that the state retrodicted from the response of a measurement apparatus is a convenient tool to fully characterize its quantum properties. We translate in terms of this state some interesting aspects of the quantum behavior of a detector, such as the nonclassicality or the non-gaussian character of its measurements. We also introduce estimators--the projectivity, the ideality, the fidelity, or the detectivity of measurements performed by the apparatus--which directly follow from the retrodictive approach. Beyond their fundamental significance for describing general quantum measurements, these properties are crucial in several protocols, in particular, in the conditional preparation of nonclassical states of light or in measurement-driven quantum information processing.     

Unfolding physics from the algebraic classification of spinor fields

After reviewing the Lounesto spinor field classification, according to the bilinear covariants associated to a spinor field, we call attention and unravel some prominent features involving unexpected properties about spinor fields under such classification. In particular, we pithily focus on the new aspects — as well as current concrete possibilities. They mainly arise when we deal with some non-standard spinor fields concerning, in particular, their applications in physics.     

Potassium Titanyl Phosphate and Its Isomorphs: Growth,Properties, and Applications

Potassium titanyl phosphate (KTP) and its isomorphs have received enormous attention in the last 2 decades. In particular, KTP assumes importance due to its large nonlinear optic and electrooptic coefficients together with the broad thermal and angular acceptance for second harmonic generation. This article provides an overview of the material aspects, structural, physical, and chemical properties and device feasibility of the KTP family of crystals. Some of the current areas of research and development along with their significance in understanding the physical properties as well as device applications are addressed. Optical waveguide fabrication processes and characteristics with their relevance to the present-day technology are highlighted. Studies performed so far have enabled us to understand the fundamental aspects of these materials and what needs to be pursued vigorously is the exploitation of their device applications to the maximum extent.     

In-medium effects on electromagnetic probes

We discuss some of the aspects of the physics of relativistic nuclear collisions, in particular those having to do with the observation of electromagnetic radiation. We concentrate on what such measurements tell us about the local, in-medium properties of the environment from which they emerge. The contributions from different sources are considered: that from the partonic sector of QCD, and that from the confined hadronic phase. Specifically, we discuss the observation of real photons and of lepton pairs at the SPS and at RHIC, and make predictions for the LHC. The role of jets is discussed.Arrival of the final proofs: 18 July 2005PACS: 25.75.-q, 12.38.Mh     

A fixture for interfacial dilatational rheometry using a rotational rheometer

In characterizing complex fluid-fluid interfaces, interfacial rheometry has become an important tool to indirectly probe the interfacial microstructure and molecular interactions. It can also be useful to obtain the constitutive properties of an interface for calculating the interfacial flows of complex fluid-fluid interfaces. A number of devices for measuring interfacial shear rheology have been designed and have been thoroughly validated. However, although a range of devices for measuring interfacial dilatational rheology exist, they do not always allow for a proper separation of the effects of dynamic surface tension, curvature elasticity, Marangoni stresses, bulk flow effects and the desired dilatational rheological material functions. In the present work it is investigated if a fixture for a standard rotational rheometer can be designed which probes the dilatational viscoelastic properties of a planar complex fluid-fluid interface. A modification of the double wall ring geometry for shear rheometry is proposed, which creates a mixed but analyzable flow field. The use of a mixed flow field inherently limits the sensitivity for the dilatational properties, but some advantages over existing techniques are presented, in particular for insoluble monolayers. More importantly, the analysis illustrate some generic aspects on the use of mixed interfacial flow fields for measuring the surface rheological properties.     

“Small and beautiful” – The novel structures and phases of nano-oxides

Low-dimensional oxide nanostructures supported on well-defined metal surfaces raise scientific interest both on a fundamental level and for potential technological applications. These systems may be regarded as artificially created hybrid materials with novel emergent properties, supporting new concepts of geometrical structure, electronics and magnetism, complex phase diagrams and particular chemical reactivity. The coupling of the oxide nano-phase to the metal support surface by electronic and elastic interactions together with the low dimensionality aspects are at the origin of the particular behaviour of these hybrid structures. By way of prototypical examples, this Prospective article highlights some of the novel properties of nano-oxides and, as a side aspect, comments on the aesthetics of their structural motifs.     

Broken ergodicity

The breakdown of ergodic behaviour is discussed as a general phenomenon in condensed matter physics. Broken symmetry is a particular case of this broken ergodicity. In a system that is non-ergodic on physical timescales the phase point is effectively confined in one subregion or component of phase space. Theoretical treatments of such systems should compute thermal averages over one component at a time. The probability distribution of physical properties can then be obtained from occurrence probabilities for different components, and moments of these distributions may be used for predicting the results of typical measurements. A two-level statistical mechanics is therefore proposed. Various aspects of the breakdown of ergodicity are discussed, including: the definition of components; mechanisms for the confinement of components; methods for computing the properties of one component; the choice of occurrence probabilities for different components; and average thermodynamic properties of broken ergodicity systems. The theory is illustrated by application to well-understood systems. It is also applied to the spin glass, which is reviewed in some detail. The broken ergodicity viewpoint is combined with a suggested characterization of the components in a spin glass, involving a bifurcation cascade. Together these provide a qualitative explanation for the irreversibility signature, the long time decays, the apparent failure of linear response theory and Maxwell relations, and blocking.     

Cosmology of Brane-Induced Gravity Models

We review various aspects of the cosmology of brane-induced gravity models. After recalling some properties of these models, we give the equations governing the cosmological dynamics in a Z ₂ symmetric case. We then discuss properties of two particular solutions of interest, a self-accelerating solution that has been proposed to provide an alternative explanation to the observed late time acceleration of the universe, and a self-flattening solution. The latter is also discussed in relation with the van Dam–Veltman–Zakharov discontinuity.     

Exact Interior Solutions for Charged Fluid Spheres

A new method is discussed to obtain the interior solution of Einstein-Maxwell equations for a charged static sphere from a known particular solutions of a similar kind. Beginning with a charged fluid interior solution reported by Patel and Pandya [11], a new interior Reissner-Nördstrom metric is obtained using this method and physical aspects of it are extensively discussed.     

Developments in nano-oscillators based upon spin-transfer point-contact devices

We review the current status of research on microwave nano-oscillators that utilize spin transfer devices with point-contact geometry, with an emphasis on the open questions that still prevent our full understanding of device properties. In particular, we examine those aspects that might affect irreproducibility of device performance. While there is a clear picture of the general principles that underlie the properties of the spin torque nano-oscillator, there are a number of details complicating the picture. We suggest that these details are potentially responsible for adversely affecting uniformity of performance from device to device. These details include (1) nonlinearities, (2) the Oersted field, (3) thermal and deterministic noise sources, and (4) non-uniformity of the spin accumulation. We suggest what role that these details might have in determining spin torque dynamics, and suggest particular avenues of investigation that might clarify whether or not these details are indeed responsible for device variability. This article is one of a series devoted to the subject of spin torque in this issue of the Journal of Magnetism and Magnetic Materials.     

Gromov-Witten classes,quantum cohomology,and enumerative geometry

The paper is devoted to the mathematical aspects of topological quantum field theory and its applications to enumerative problems of algebraic geometry. In particular, it contains an axiomatic treatment of Gromov-Witten classes, and a discussion of their properties for Fano varieties. Cohomological Field Theories are defined, and it is proved that tree level theories are determined by their correlation functions. Application to counting rational curves on del Pezzo surfaces and projective spaces are given.     

On causal dynamics without metrisation: Part I

Synopsis By a careful topological examination of certain aspects of measurement processes, one reaches the unorthodox conclusion that it is not legitimate to assume that three-space is metrisable throughout the universe. The examination consists of an identification of the role of the separation axioms in the conventional mathematical formulation of the information we extract from actual measurements. To provide a means of handling the limitations introduced by errors of measurement, a species of local structure is proposed that is a particular example of a Zeeman tolerance space. Some homology properties relating to the way in which measurements containing errors are adjoined are deduced for spaces possessing the proposed structure, and some simple properties of transformations of such spaces are given.This work was undertaken and completed whilst the author was at the Post Office Research Station, Dollis Hill, London, N.W.2.     

氧化物超导体的磁通动力学

考虑到氧化物高温超导体与传统超导体磁性质之间的不同之处，文章从不可逆线的解释，Ａｎｄｅｒｓｏｎ模型的一种修正方案以及对Ｓ－Ｔ关系曲线的解释等三个方面对高温超导体的磁通动力学行为作了简要的介绍。     

High-pressure synthesized materials: treasures and hints

This short review covers some particular aspects of the production of new materials under high pressures. Despite the fact that there is an extremely wide range of new high-pressure synthesized substances with unique properties, a commercial synthesis has been used up to date only for producing superhard materials – these are real treasures of today’s industry. At the same time, as should be underlined here, high-pressure experiments often give scientists material with helpful hints of what new intriguing substances can exist in principle. This is true both for new superhard, semiconducting, magnetic, superconducting, optical materials already synthesized under pressure and a large number of hypothetic new polymers from low-Z elements.