Manganese ferrite-polyaniline hybrid materials: Electrical and magnetic properties

Magnetic MnFe₂O₄ nanopowders were synthesized by an original solvothermal method in the absence and in the presence of tetra-n-butylammonium bromide (TBAB) and Tween 80 (TW) as surfactants. Manganese ferrite/polyaniline (PANI) hybrid materials were synthesized by in situ polymerization of aniline on the surface of MnFe₂O₄ using ammonium persulfate as oxidant. The purpose of the study was to investigate the influence of the two surfactants on the properties of the MnFe₂O₄ powders and of their composites with PANI. The specific surface area, the cumulative surface area of pores and the cumulative volume of pores are influenced by the nature of surfactant in case of MnFe₂O₄ powders and are higher by comparison to those of the MnFe₂O₄/PANI hybrid materials. The values of saturation magnetization in case of MnFe₂O₄ powders are higher than those of the hybrid materials and are not influenced by the surfactant nature. These features revealed that MnFe₂O₄ powders can be efficiently used as adsorbents for the purification of wastewaters. The values of the electrical conductivity of the composites exhibit a significant increase in comparison to the MnFe₂O₄ powders and depend on the surfactant nature. The highest value of electrical conductivity was achieved by the composite obtained using Tween 80 as surfactant (σ_DC = 54.5·10^?5S?m^?1) which was close to that of PANI (σ_DC = 61.2·10^?5 S?m^?1). The fact that the magnetic and electric properties of the synthesized MnFe₂O₄/PANI composites can be changed by design, demonstrate the high potential of these materials to be used in magneto-electric applications.     

The contribution of proteomics towards deciphering the enigma of Coxiella burnetii

Coxiella burnetii, the causative agent of Q fever, is an intracellular bacterium and a potential weapon for bioterrorism. The widespread throughout the world, zoonosis is manifested clinically as a self-limited febrile illness, as pneumonia (acute Q fever) or as a chronic illness with endocarditis being its major complication. The recent Netherlands Q fever outbreak has driven the bacterium from a relatively cryptic, underappreciated, “niche” microorganism on the sideline of bacteriology, to one of possibly great impact on public health. Advances in the study of this microorganism proceeded slowly, primarily due to the, until recently, obligatory intracellular nature of the pathogen that in its virulent phase I must be manipulated under biosafety level-3 conditions. Proteomic studies, in particular, have generated a vast amount of information concerning several aspects of the bacterium such as virulence factors, detection/diagnostic and immunogenic biomarkers, inter-/intraspecies variation, resistance to antibiotics, and secreted effector proteins with significant clinical impact. The phenomenon observed following the genomics era, that of generation and accumulation of huge amount of data that ultimately end up unexploited on several databases, begins to emerge in the proteomics field as well. This review will focus on the advances in the field of C. burnetii proteomics through MS, attempting in parallel to utilize some of the proteomics findings by suggesting future directions for the improvement of Q fever diagnosis and therapy.     

Estimation of unknown speaker’s height from speech

In the present study, we propose a regression-based scheme for the direct estimation of the height of unknown speakers from their speech. In this scheme every speech input is decomposed via the openSMILE audio parameterization to a single feature vector that is fed to a regression model, which provides a direct estimation of the persons’ height. The focus in this study is on the evaluation of the appropriateness of several linear and non-linear regression algorithms on the task of automatic height estimation from speech. The performance of the proposed scheme is evaluated on the TIMIT database, and the experimental results show an accuracy of 0.053 meters, in terms of mean absolute error, for the best performing Bagging regression algorithm. This accuracy corresponds to an averaged relative error of approximately 3%. We deem that the direct estimation of the height of unknown people from speech provides an important additional feature for improving the performance of various surveillance, profiling and access authorization applications.     

An overview of web accessibility in Greece: a comparative study 2004–2008

This communication reports on the results of a web accessibility audit of public Web sites in Greece. The audit was conducted in 2008 by the Human Computer Interaction Laboratory of the Institute of Computer Science of FORTH, in its capacity as the Greek National Contact Centre of the European Design for All e-Accessibility Network. In an earlier e-Accessibility study in 2004, that evaluated approximately 250 public and commercial Web sites in Greece, 73% of the sample failed to meet the most basic requirements for web accessibility (). Four years later, in the context of a re-audit, a similar sample was examined for compliance with the same web accessibility standard (WCAG 1.0), as set by the Web Accessibility Initiative of the World Wide Web Consortium. The accessibility checks were conducted during the period from March to September 2008. A comparison of the results indicates that although new web development technologies may have been employed, instead of improving the overall status of e-accessibility, this has resulted in a serious deterioration in overall accessibility levels. Such findings—85% of sites failed to comply with Level A—suggest that Greek Web sites are likely to present even more significant access barriers to people with disability than in the past. As Web Accessibility is poorly understood and, until today, new platforms have failed to deliver products that conform to WCAG, the need emerges for a concrete legislative framework to set accessibility specifications for all public Web sites in Greece.     

Influence of Macromolecular Brushes with Polyimide Backbones and Poly(methyl methacrylate) Side Chains on Structure,Physical, and Transport Properties of Polyphthalamide

Composite films based on polyamide (poly(m-phenylene-iso-phthalamide)) (PA) and a brush-like polymer with polyimide (PI) backbone and side poly(methyl methacrylate) chains (PI-PMMA) were prepared by mixing individual solutions of PA and PI-PMMA and subsequent film casting. Macromolecular brushes with the same backbone length and density of side chains but with various lengths of side PMMA chains were synthesized via activator generated by electron transfer atom transfer radical polymerization. Interactions between PA and PI-PMMA, as well as distribution of PI-PMMA filler inside the PA matrix, were studied by viscometry, dynamic light scattering, differential scanning calorimetry, scanning electron microscopy, and IR spectroscopy. The mechanical properties of polymer samples were also investigated. Microphase separation was revealed in PA/PI-PMMA films. The length of side chains influences interactions between PA and PI-PMMA. At the same time, the degree of reduction in the rigidity parameters and in the elasticity parameter depends on the side chain length. Diffusion membranes were prepared on the basis of compositions with the best mechanical properties; these membranes proved to be highly efficient in pervaporation of methanol–hexane mixture. It was established that the fluxes and separation factors of the studied membranes are several times higher as compared to the corresponding characteristics of known commercial membranes. POLYM. ENG. SCI., 60:481–490, 2020. © 2019 Society of Plastics Engineers     

Underapproximation of procedure summaries for integer programs

International Journal on Software Tools for Technology Transfer - We show how to underapproximate the procedure summaries of recursive programs over the integers using off-the-shelf analyzers for...     

Effect of vitamin E supplementation on neutrophil function, milk composition and plasmin activity in dairy cows in a commercial herd

Fifty-six Holstein dairy cows from a commercial dairy herd in the Northern part of Greece were used to determine the effect of vitamin E supplementation on immune parameters, milk composition and milk quality. Cows were assigned to one of two experimental groups: control (no vitamin E supplementation) and vitamin E supplementation. Supplementation of vitamin E started 4 weeks prior to and continued up to 12 weeks after parturition. Supplementation included daily oral administration of vitamin E at 3000 i.u./cow prepartum and was reduced to 1000 i.u./cow post partum. Blood samples were collected weekly for 8 weeks starting 4 weeks before parturition, neutrophils were isolated and the following parameters were determined in neutrophils activated by phorbol myristate acetate: total cell-associated and membrane-bound urokinase plasminogen activator (u-PA) activity and superoxide production. Milk samples were collected weekly and fat, protein, lactose, somatic cell count (SCC), plasmin and plasminogen-derived activity were determined. Activated neutrophils isolated from cows that received supplemental vitamin E had higher (P<0.01) total and membrane-bound u-PA activities during the first 3 weeks after parturition and higher (P<0.01) superoxide production during week 1 prepartum and week 1 post partum compared with the corresponding values of activated neutrophils isolated from control cows. Vitamin E supplementation had no effect (P=0.28) on plasminogen-derived activity in milk. Milk obtained from cows that received supplemental vitamin E had SCC lower by 25% (P<0.05) and plasmin lower by 30% (P<0.01) than corresponding values in milk obtained from control cows. The reduction in plasmin as a result of vitamin E supplementation is very beneficial to the dairy industry because plasmin reduces the cheese-yielding capacity of milk, affects the coagulating properties of milk and its overall ability to withstand processing during cheesemaking. In conclusion, vitamin E supplementation had positive effects on the function of bovine neutrophils and milk quality in a commercial dairy herd.     

Amplitude-modulated laser imager

Laser systems have been developed to image underwater objects. However, the performance of these systems can be severely degraded in turbid water. We have developed a technique using modulated light to improve underwater detection and imaging. A program, Modulated Vision System (MVS), which is based on a new theoretical approach, has been developed to predict modulated laser imaging performance. Experiments have been conducted in a controlled laboratory environment to test the accuracy of the theory as a function of system and environmental parameters. Results show a strong correlation between experiment and theory and indicate that the MVS program can be used to predict future system performance.