Effect of fluid flow on cavitation erosion of materials under exposure to vibrations from a hydrodynamic generator

The results of investigation of cavitation erosion of lead in various places of a hydrodynamic-generator submerged jet are presented. Features of erosion caused by the effect of flow are established. It can both strengthen the erosion intensity and weaken it in dependence on the angle of incidence. The stratification of air bubbles under the action of pressure waves is possible in the flow under the interaction with the surface of objects. The flow can change the number of air bubbles participating in the cavitation near the surface. It can also influence the mechanical effect on the surface of the tested materials inducing their nonuniform deformation. All the factors listed affect the cavitation erosion complicating considerably the physics of the process.     

Nonparametric identification of asymmetric nonlinear vibration systems with the Hilbert transform

The objective of the paper is presenting a simple and more accurate technique for precise identification of nonlinear elastic force functions acting in asymmetric vibration systems. The identification procedure based on the Hilbert transform is a nonparametric one; it does not require a priori information about the system structure or its parameters. The examples of the identification of asymmetric classic vibration nonlinear models – the Helmholtz and the double-well Duffing oscillators – are investigated.     

Poly(vinyl chloride) Nanocomposites

Poly(vinyl chloride) is one of the major thermoplastics beside other commodities polymers like polyethylene and polystyrene. However, some of its main characteristics such as plasticity, thermal and photo stability are inferior to other commodity polymers. Adding nano scale inorganic fillers to poly(vinyl chloride) or other polymers in view to obtain polymer nanocomposites with superior properties has drawn the attention of many researchers in the last decades. Poly(vinyl chloride) nanocomposites are obtained mainly by in situ polymerization, solution based or mixing techniques. The resulting products show improvement of most important properties of poly(vinyl chloride) such as thermal, mechanical, rheological, flammability, antibacterial, etc. This paper presents preparation ways of poly(vinyl chloride) nanocomposites using different nano fillers and the improved properties compared with those of virgin poly(vinyl chloride).     

Relationship between Reactivity Ratios and Configuration for Donor—Acceptor Type Copolymers

For binary copolymers from an acrylic monomer (acceptor type, M¹) and an aromatic-substituted monomer (donor type, M₂) a linear relation between log (r₂/r¹) and the probability of “coisotactic” alternating addition is observed. This can be a proof for the influence of monomer polarity on the copolymer configuration.     

Acrylic Terpolymer-Based Blends with Improved Properties

Blending of acrylic terpolymer (AT) with vinyl acetate-vinyl chloride (VAc-VC) copolymer, polyvinyl alcohol (PVA) polymer, and polyvinyl acetate (PVAc) polymer, respectively, resulted in sealant compositions with improved properties and enhanced outdoor weathering resistance. The morphology of these blends was studied by SEM, energy-dispersive x-ray analysis (EDXA), and DSC. The blends are heterogeneous and consist of a continuous phase which is either pure or mixed AT and a particulate phase having the morphology of the added component. The particulate phase of AT and AT-(VAc-VC) copolymer blends contains mixed AT, whereas that of AT-PVA and AT-PVAc does not. The AT-based blends have generally improved mechanical properties (e.g., ultimate tensile strength, adhesive strength). The improvement in mechanical properties is particularly strong in mixtures of AT with (VAc-VC) copolymer, probably because the added component has greater specific interaction capabilities with AT than the polymers incorporated in the other blends. Whereas the unblended AT has very low outdoor durability, the AT-based blends display enhanced resistance to weathering, as evidenced by substantially higher ultimate tensile strength of weathered specimens than those of the controls (unweathered).     

Mass spectrometry imaging as a tool for surgical decision‐making

Despite significant advances in image‐guided therapy, surgeons are still too often left with uncertainty when deciding to remove tissue. This binary decision between removing and leaving tissue during surgery implies that the surgeon should be able to distinguish tumor from healthy tissue. In neurosurgery, current image‐guidance approaches such as magnetic resonance imaging (MRI) combined with neuronavigation offer a map as to where the tumor should be, but the only definitive method to characterize the tissue at stake is histopathology. Although extremely valuable information is derived from this gold standard approach, it is limited to very few samples during surgery and is not practically used for the delineation of tumor margins. The development and implementation of faster, comprehensive, and complementary approaches for tissue characterization are required to support surgical decision‐making – an incremental and iterative process with tumor removed in multiple and often minute biopsies. The development of atmospheric pressure ionization sources makes it possible to analyze tissue specimens with little to no sample preparation. Here, we highlight the value of desorption electrospray ionization as one of many available approaches for the analysis of surgical tissue. Twelve surgical samples resected from a patient during surgery were analyzed and diagnosed as glioblastoma tumor or necrotic tissue by standard histopathology, and mass spectrometry results were further correlated to histopathology for critical validation of the approach. The use of a robust statistical approach reiterated results from the qualitative detection of potential biomarkers of these tissue types. The correlation of the mass spectrometry and histopathology results to MRI brings significant insight into tumor presentation that could not only serve to guide tumor resection, but that is also worthy of more detailed studies on our understanding of tumor presentation on MRI. Copyright © 2013 John Wiley & Sons, Ltd.     

Landscape of supersymmetric particle mass hierarchies and their signature space at the CERN Large Hadron Collider

The minimal supersymmetric standard model with soft breaking has a large landscape of supersymmetric particle mass hierarchies. This number is reduced significantly in well-motivated scenarios such as minimal supergravity and alternatives. We carry out an analysis of the landscape for the first four lightest particles and identify at least 16 mass patterns, and provide benchmarks for each. We study the signature space for the patterns at the CERN Large Hadron Collider by analyzing the lepton+ (jet> or =2) + missing P{T} signals with 0, 1, 2, and 3 leptons. Correlations in missing P{T} are also analyzed. It is found that even with 10 fb{-1} of data a significant discrimination among patterns emerges.     

The dielectric response of interfacial water—from the ordered structures to the single hydrated shell

Water is the universal solvent in nature. Does this imply, however, that its interaction with its environment is also a universal feature? While this question maybe too fundamental to be answered by one method only, we present evidence that the broadening of the dielectric spectra of water presents universal features of dipolar interactions with different types of matrixes. If in aqueous solutions the starting point of water’s state can be considered as bulk, with only partial interactions with the solute, then the state of water adsorbed in heterogeneous materials is determined by various hydration centers of the inhomogeneous material (the matrix) and it is significantly different from the bulk. In both cases, the dielectric spectrum of water is symmetrical and can be described by the Cole–Cole (CC) function. The phenomenological model that describes a physical mechanism of the dipole–matrix interaction in complex systems underlying the CC behavior has been applied to water adsorbed in porous glasses. It was then extended to analyses of the dynamic and structural behavior of water in nonionic and ionic aqueous solutions. The same model is then used to analyze the CC relaxation processes observed in clays, aqueous solutions of nucleotides, and amino acids.     

Radiothermoluminescence of linear polyethylene with extended-chain crystals

It has been shown that a radiothermoluminescence curve of polyethylene with extended-chain crystals can be separated into components corresponding to intracrystalline and disordered regions of the polymer by introducing an electron scavenger.