Random poly(ε‐caprolactone‐L‐alanine) by direct melt copolymerization

A series of random polyesteramides (PEAs) with a range of molar composition from 90/10 to 50/50 were synthesized by direct melt polycondensation of ε‐caprolactone and l ‐alanine. Their structure was fully characterized by Fourier transform IR and NMR spectroscopy. The resulting copolymers are completely amorphous with the exception of PEA‐90/10 which possesses a semicrystalline structure. These PEAs present increasing glass transition temperatures at increasing l ‐alanine contents and exhibit fairly good thermal stability with 10% mass loss temperatures reaching 315 °C. © 2020 Society of Industrial Chemistry     

Lipopolysaccharide-induced expression of reactive oxygen species and peroxynitrite in the guinea pig vestibular organ

The purpose of this study was to investigate the occurrence of reactive oxygen species and peroxynitrite in the vestibular organ of the guinea pig following inoculation with bacterial lipopolysaccharide (LPS). The animals were injected transtympanically with 1 mg of LPS 24 h after the intraperitoneal injection of 0.1 mg LPS. Forty-eight hours after the inoculation, varying degrees of degeneration of the vestibular end organs were observed. Immunohistochemical study revealed immunoreactivity to xanthine oxidase (which generates O-2) in the vestibular organ after inoculation with LPS. Immunohistochemical investigation with a specific antinitrotyrosine antibody also showed intense staining of sensory epithelium, fluid transporting cells and the endolymphatic sac, suggesting formation of peroxynitrite in the vestibular organ through the reaction of NO with O-2. On the basis of these data, it can be concluded that NO together with O-2, which form more reactive peroxynitrite, may be the most important pathogenic agents in LPS-induced labyrinthitis in the guinea pig.     

Nonmonotonous Variation of the Superconducting Parameters of Neutron Irradiated Li-Doped YBa2Cu3O7?x

The effect of thermal and epithermal neutron irradiation on the superconducting critical temperature and critical current density of some Li-doped YBa₂Cu₃O_7–x samples was studied. The critical temperature exhibits a peak and the critical current density a valley in their dependence on neutron fluence, for moderate dose. A simple model, based on the Van Hove scenario and the kinetics of the defect production, is used to describe both phenomena.     

Magnetic AC susceptibility in Bi2Sr2CaCu2O8 single crystals

We measured the temperature dependence of the ac susceptibility in Bi₂Sr₂CaCu₂O₈ single crystals. The penetration fieldH* was determined, at different temperatures, from the field dependence ofX″ in the framework of the critical state model. Using a very simple formula, we estimated the values of the critical current density near T_c, which are consistent with the usually reported data for this material.     

Sintering time and properties of YBa2Cu3O～7 superconducting ceramics

The effect of annealing duration in oxygen flow on the superconducting characteristics of YBa₂Cu₃O₇ bulk ceramics was investigated by structural, electrical, magnetic, and electronic microscopy investigations. The long-time annealing is deleterious for the superconductivity in YBa₂Cu₃O₇ ceramics. The optimum time interval for annealing is from 20 to 70 h at 950°C, and within this range the maximum value ofT _c is obtained.     

Social Media Technologies’ Use for the Competitive Information and Knowledge Sharing,and Its Effects on Industrial SMEs’ Innovation

ABSTRACT

The effective use of technologies supporting decision making is essential to companies’ survival. Recent studies analyzed social media technologies (SMT) in the context of small- and medium-sized enterprises (SMEs), contributing to the discussion on SMT benefits from the marketing perspective. This article focuses on the effects of SMT use on innovation. Our findings provide empirical evidence on the positive effects of SMT use for acquiring external information and for sharing knowledge and innovation performance.     

Contract-based modeling and verification of timed safety requirements within SysML

In order to cope with the growing complexity of critical real-time embedded systems, systems engineering has adopted a component-based design technique driven by requirements. Yet, such an approach raises several issues since it does not explicitly prescribe how system requirements can be decomposed on components nor how components contribute to the satisfaction of requirements. The envisioned solution is to design, with respect to each requirement and for each involved component, an abstract specification, tractable at each design step, that models how the component is concerned by the satisfaction of the requirement and that can be further refined toward a correct implementation. In this paper, we consider such specifications in the form of contracts. A contract for a component consists in a pair (assumption, guarantee) where the assumption models an abstract behavior of the component’s environment and the guarantee models an abstract behavior of the component given that the environment behaves according to the assumption. Therefore, contracts are a valuable asset for the correct design of systems, but also for mapping and tracing requirements to components, for tracing the evolution of requirements during design and, most importantly, for compositional verification of requirements. The aim of this paper is to introduce contract-based reasoning for the design of critical real-time systems made of reactive components modeled with UML and/or SysML. We propose an extension of UML and SysML languages with a syntax and semantics for contracts and the refinement relations that they must satisfy. The semantics of components and contracts is formalized by a variant of timed input/output automata on top of which we build a formal contract-based theory. We prove that the contract-based theory is sound and can be applied for a relatively large class of SysML system models. Finally, we show on a case study extracted from the automated transfer vehicle (http://www.esa.int/ATV) that our contract-based theory allows to verify requirement satisfaction for previously intractable models.