Mechanical properties of swelled vulcanizates of polar diene elastomers

Rubber elements, which usually form a major part of different isolators of vibrations, are generally easily swelled by oils, greases, or fuels. This leads to meaningful changes of their mechanical characteristics and shortening of durability of rubber components in service. The influence of the semisynthetic motor oil on mechanical and, particularly, dynamic properties of swelled vulcanizates of the polar diene rubber, chloroprene (CR) and acrylonitrile‐butadiene (NBR), is estimated in this article. These elastomers, as is widely known, are resistant to the mineral oils absorption. However, our investigations showed that even a small degree of swelling of the vulcanizates causes decrease of their mechanical properties and considerable changes of the dynamic characteristics of the samples. The obtained results have shown the need to take into account the environment in which isolators of vibrations and dampers have worked, while designing the suitable composition of rubber compounds. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

The Etiology of Cholelithiasis in Children and Adolescents—A Literature Review

The incidence of gallstone disease has increased in recent years. The pathogenesis of cholelithiasis is not fully understood. The occurrence of the disease is influenced by both genetic and environmental factors. This article reviews the literature on cholelithiasis in children, with the exception of articles on hematological causes of cholelithiasis and cholelithiasis surgery. The aim of this review is to present the latest research on the pathogenesis of gallstone disease in children. The paper discusses the influence of all factors known so far, such as genetic predisposition, age, infections, medications used, parenteral nutrition, and comorbidities, on the development of gallstone disease. The course of cholelithiasis in the pediatric population is complex, ranging from asymptomatic to life-threatening. Understanding the course of the disease and predisposing factors can result in a faster diagnosis of the disease and administration of appropriate treatment.     

Involvement of circRNAs in the Development of Heart Failure

In recent years, interest in non-coding RNAs as important physiological regulators has grown significantly. Their participation in the pathophysiology of cardiovascular diseases is extremely important. Circular RNA (circRNA) has been shown to be important in the development of heart failure. CircRNA is a closed circular structure of non-coding RNA fragments. They are formed in the nucleus, from where they are transported to the cytoplasm in a still unclear mechanism. They are mainly located in the cytoplasm or contained in exosomes. CircRNA expression varies according to the type of tissue. In the brain, almost 12% of genes produce circRNA, while in the heart it is only 9%. Recent studies indicate a key role of circRNA in cardiomyocyte hypertrophy, fibrosis, autophagy and apoptosis. CircRNAs act mainly by interacting with miRNAs through a “sponge effect” mechanism. The involvement of circRNA in the development of heart failure leads to the suggestion that they may be promising biomarkers and useful targets in the treatment of cardiovascular diseases. In this review, we will provide a brief introduction to circRNA and up-to-date understanding of their role in the mechanisms leading to the development of heart failure.     

Species Phylogeny versus Gene Trees: A Case Study of an Incongruent Data Matrix Based on Paphiopedilum Pfitz. (Orchidaceae)

The phylogeny of the genus Paphiopedilum based on the plastome is consistent with morphological analysis. However, to date, none of the analyzed nuclear markers has confirmed this. Topology incongruence among the trees of different nuclear markers concerns entire sections of the subgenus Paphiopedilum. The low-copy nuclear protein-coding gene PHYC was obtained for 22 species representing all sections and subgenera of Paphiopedilum. The nuclear-based phylogeny is supported by morphological characteristics and plastid data analysis. We assumed that an incongruence in nuclear gene trees is caused by ancestral homoploid hybridization. We present a model for inferring the phylogeny of the species despite the incongruence of the different tree topologies. Our analysis, based on six low-copy nuclear genes, is congruent with plastome phylogeny and has been confirmed by phylogenetic network analysis.     

Robust gossiping with an application to consensus

We study deterministic gossiping in synchronous systems with dynamic crash failures. Each processor is initialized with an input value called rumor. In the standard gossip problem, the goal of every processor is to learn all the rumors. When processors may crash, then this goal needs to be revised, since it is possible, at a point in an execution, that certain rumors are known only to processors that have already crashed. We define gossiping to be completed, for a system with crashes, when every processor knows either the rumor of processor v or that v has already crashed, for any processor v. We design gossiping algorithms that are efficient with respect to both time and communication. Let t<n be the number of failures, where n is the number of processors. If , then one of our algorithms completes gossiping in O(log²t) time and with O(npolylogn) messages. We develop an algorithm that performs gossiping with O(n^1.77) messages and in O(log²n) time, in any execution in which at least one processor remains non-faulty. We show a trade-off between time and communication in gossiping algorithms: if the number of messages is at most O(npolylogn), then the time has to be at least . By way of application, we show that if n−t=Ω(n), then consensus can be solved in O(t) time and with O(nlog²t) messages.     

VUV spectroscopy and low temperature thermoluminescence of LSO:Ce and YSO:Ce

Radioluminescence and UV-excited photoluminescence spectra, photoluminescence time profiles, thermoluminescence glow curves and gamma-excited energy spectra (determining scintillation light yields) of several Lu₂SiO₅:Ce and Y₂SiO₅:Ce samples were recorded. The results are analyzed with attention focused on possible correlations between trap distributions, VUV responses, and light yields. The aspect of two distinct sites occupied by Ce³⁺ ions is also discussed.     

Bang-bang Controls and Piecewise Constant ones for Continuous Roesser Systems

In the paper, we prove the bang-bang principle for a continuous linear nonautonomous Roesser system and some approximation result (with respect to piecewise constant controls) for a continuous nonautonomous Roesser system which is linear in the state and nonlinear in the control. Published online: April 2006 The preparation of this paper was supported by the State Committee for Scientific Research, Poland, under Grant 7 T11A 004 21     

Structure and properties of polyolefin blends

Blends of ethylene–propylene–diene rubber (EPDM) and low density polyethylene (PE_id) or isotactic polypropylene (iPP) crosslinked by dicumyl peroxide (DCP) have been prepared. Their morphology, reactivity of the components and crystallinity have been studied. The blends are microheterogeneous. Both plastomers, but particularly iPP, decrease the crosslinking efficiency of EPDM by DCP. It was found that they also influence the mechanical properties of the blends. The effect of iPP is far more pronounced than that of PE_Id, because of an increase in crystalline phase content. iPP particles play a role as nuclei for propylene monomer units in EPDM, whereas PE_Id particles are solvated by the elastomer matrix.