On the application of laser shock peening for retardation of surface fatigue cracks in laser beam‐welded AA6056

The present study aims to investigate the extent to which the fatigue behaviour of laser beam‐welded AA6056‐T6 butt joints with an already existing crack can be improved through the application of laser shock peening. Ultrasonic testing was utilized for in situ (nondestructive) measurement of fatigue crack growth during the fatigue test. This procedure allowed the preparation of welded specimens with surface fatigue cracks with a depth of approximately 1.2 mm. The precracked specimens showed a 20% reduction in the fatigue limit compared with specimens without cracks in the as‐welded condition. Through the application of laser shock peening on the surfaces of the precracked specimens, it was possible to recover the fatigue life to the level of the specimens tested in the as‐welded condition. The results of this study show that laser shock peening is a very promising technique to recover the fatigue life of welded joints with surface cracks, which can be detected by nondestructive testing.     

Theoretical Approach to Optimization of Home Subscriber Server in IP Multimedia Subsystem

Wireless Personal Communications - Our paper deals with structure of Home Subscriber Server in IP Multimedia Subsystem and mathematical models for optimizing this database. The aim of our work is...     

Complex Transposon Insertion as a Novel Cause of Pompe Disease

Pompe disease (OMIM#232300) is an autosomal recessive lysosomal storage disorder caused by mutations in the GAA gene. According to public mutation databases, more than 679 pathogenic variants have been described in GAA, none of which are associated with mobile genetic elements. In this article, we report a novel molecular genetic cause of Pompe disease, which could be hardly detected using routine molecular genetic analysis. Whole genome sequencing followed by comprehensive functional analysis allowed us to discover and characterize a complex mobile genetic element insertion deep in the intron 15 of the GAA gene in a patient with infantile onset Pompe disease.     

Molecular characterization of statistical copolymers: 1. Potential and limitations of full adsorption–desorption procedure in separation of statistical copolymers

Dynamic integral desorption isotherms for a series of poly(methyl methacrylate) homopolymers and poly(methyl methacrylate)–polystyrene statistical copolymers were measured. Nonporous silica was the full adsorption–desorption (FAD) column packing and various adsorption‐promoting and desorption‐promoting liquids were used. The aim of this study was to evaluate the applicability of the FAD approach for separation of statistical copolymers. The effects of the adsorbing liquid and desorbing liquid nature were demonstrated on the positions and shapes of desorption isotherms. The desorption isotherms also strongly depended on both (co)polymer molar mass and copolymer chemical composition. This indicates large fractionation potential of the FAD procedure. Simultaneously, the interference of both above parameters prevents the direct use of FAD for fractionation of the copolymers. It is anticipated that the fractionation and/or reconcentration potential of the FAD procedure can be very effectively utilized in combination of FAD with size‐exclusion chromatography and/or with gradient elution liquid adsorption chromatography. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 857–864, 2000     

Approximate formulae for numerical inversion of Laplace transforms

Most methods for the numerical calculation of inverse Laplace transformations f(t) = L⁻¹[F(s)] have serious limitations concerning the class of functions F(s) that can be inverted or the achievable accuracy. The procedures described in the paper can be used to invert rational as well as irrational or transcendental functions of the complex variable s. The required accuracy of the results can be enhanced without changing the algorithm, only at the cost of a longer computation time. The described methods were verified with many examples including transients in lumped/distributed systems with sections of lossy multiconductor transmission lines or with distributed RC elements. © 1998 John Wiley & Sons, Ltd.     

Understanding surface partial discharges in HV coils and the role of semi-conductive protection

An electrical insulating system in high voltage rotating machines is subjected to several stresses that cause changes of material properties during its lifetime. This phenomenon reduces progressively ability of the insulation to withstand the service stresses. Internal partial discharges can be located inside the high voltage insulation and usually they are dangerous for life-cycle duration. Surface discharges are generated at the solid/air interface in the gaps of machine stator slots or at the slot exits. Surface discharges can cause more intensive deterioration of the insulation, accelerate aging processes and definitively take aim toward premature failure of the machine. The application of conductive or semi-conductive protection layer provides certain protection for solid insulation from these discharges. Semi-conductive corona protection tapes are used on the coils at the slot exit region to electrical field control and prevent surface discharges. Laboratory measurements of the surface partial discharge quantities in specimens of high voltage coils with mica insulation were performed. The aim of the paper is to describe theoretically the development of surface discharges in rotating machines and to present surface partial discharge development in HV motors when semi-conductive layer protection is missing. The results can be found useful to understand better the surface discharge development and importance of high-quality semi-conductive protection technology.     

Immunomodulatory efficiency of poly(2-oxazolines)

Poly(2-oxazolines) represent promising polymer materials for biomedical applications. The activation of mouse lymphoid macrophage line P388.D1 (clone 3124) by two selected representatives of poly(2-oxazolines), namely poly(2-ethyl-2-oxazoline) (PETOX100) and poly[2-(4-aminophenyl)-2-oxazoline-co-2-ethyl-2-oxazoline] (AEOX10), was assessed in vitro. The immunomodulatory efficacy of both polymers was evaluated via the induced release of pro-inflammatory cytokines (TNF-α, IL-1α and IL-6) and the acceleration of reactive free radicals. The present study revealed effective structure-immunomodulating associations of AEOX10 and PETOX100, which are desirable in biomedical and pharmaceutical applications of aliphatic and aromatic poly (2-oxazolines) in vivo.