37 research outputs found
Polymerisation and surface modification of methacrylate monoliths in polyimide channels and polyimide coated capillaries using 660 nm light emitting diodes
An investigation into the preparation of monolithic separation media utilising a cyanine dye sensitiser/triphenylbutylborate/N-methoxy-4-phenylpyridinium tetrafluoroborate initiating system activated by 660nm light emitting diodes is reported. The work demonstrates multiple uses of red- light initiated polymerisation in the preparation of monolithic stationary phases within polyimide and polyimide coated channels and the modification of monolithic materials with molecules which absorb strongly in the UV region. This initiator complex was used to synthesise poly(butyl methacrylate- co-ethylene dimethacrylate) and poly(methyl methacrylate-co-ethylene dimethacrylate) monolithic stationary phases in polyimide coated fused silica capillaries of varying internal diameters, as well as within polyimide micro-fluidic chips. The repeatability of the preparation procedure and resultant mono- lithic structure was demonstrated with a batch of poly(butyl methacrylate-co-ethylene dimethacrylate) monoliths in 10
Enterococcus devriesei sp. nov., associated with animal sources
http://ijs.sgmjournals.org/The taxonomic position of two bovine strains, LMG 13603 and LMG 14595, assigned to the species Enterococcus raffinosus on the basis of biochemical features, was reinvestigated.
Both reference strains and two other isolates, 6/1 (=LMG 22829) originating from a
charcoal-broiled river lamprey and IE38.4 (=LMG 22830) from the air of a poultry slaughter by-product processing plant, occupied a clearly separate position, on the basis of sequence analysis of the housekeeping gene pheS (encoding the phenylalanyl-tRNA synthase a-subunit), relative to the type strain of E. raffinosus and all other enterococcal species with validly published names. 16S rRNA gene sequencing of strains LMG 13603, LMG 14595, 6/1 and IE38.4 confirmed their phylogenetic position in the Enterococcus avium species group, there being more than 99% 16S rRNA gene sequence similarity to most members of the group, including E. raffinosus, and revealed Enterococcus pseudoavium as the closest phylogenetic relative (99,8–99,9 %). Further phenotypic and genotypic analyses using whole-cell-protein electrophoresis, (GTG)5-PCR fingerprinting, ribotyping and DNA–DNA hybridization experiments
demonstrated that all four strains represent a novel enterococcal species, for which the name Enterococcus devriesei sp. nov. is proposed. The type strain is LMG 14595T (=CCM 7299T)
Conceptual framework for programming skilss development based on microlearning and automated source code evaluation in virtual learning environment
Understanding how software works and writing a program are currently frequent requirements
when hiring employees. The complexity of learning programming often results in educational
failures, student frustration and lack of motivation, because different students prefer different learning
paths. Although e-learning courses have led to many improvements in the methodology and the
supporting technology for more effective programming learning, misunderstanding of programming
principles is one of the main reasons for students leaving school early. Universities face a challenging
task: how to harmonise students’ education, focusing on advanced knowledge in the development of
software applications, with students’ education in cases where writing code is a new skill. The article
proposes a conceptual framework focused on the comprehensive training of future programmers
using microlearning and automatic evaluation of source codes to achieve immediate feedback for
students. This framework is designed to involve students in the software development of virtual
learning environment software that will provide their education, thus ensuring the sustainability of
the environment in line with modern development trends. The paper’s final part is devoted to verifying
the contribution of the presented elements through quantitative research on the introductory
parts of the framework. It turned out that although the application of interactive features did not
lead to significant measurable progress during the first semester of study, it significantly improved
the results of students in subsequent courses focused on advanced programming
In situ investigation of the cytotoxic and interfacial characteristics of titanium when galvanically coupled with magnesium using scanning electrochemical microscopy
Recently, the cytotoxic properties of galvanically coupled Mg-Ti particles have been shown to
different cells, although this cytotoxic effect has been attributed mainly to Mg due to its
tendency to undergo activation when coupled with Ti forming a galvanic cell consisting of an
anode (Mg) and a cathode (Ti). However, the role of the Ti cathode has been ignored in
explaining the cytotoxic effect of Mg-Ti particles due to its high resistance to corrosion. In this
work, the role of titanium (Ti) in the cytotoxic mechanism of galvanically coupled Mg-Ti
particles was examined. A model galvanic cell was prepared to simulate the Mg-Ti particles.
The electrochemical reactivity of the Ti sample and the pH change above it due to galvanic
coupling with Mg were investigated using scanning electrochemical microscopy (SECM). It
was observed that the Ti surface changed from passive to electrochemically active when
coupled with Mg. Furthermore, after only 15 min galvanic coupling with Mg, the pH in the
electrolyte volume adjacent to the Ti surface increased to an alkaline pH value. The effects of
the galvanic coupling of Ti and Mg, as well as of the alkaline pH environment, on the viability
of Hs27 fibroblast cells were investigated. It was shown that the viability of Hs27 cells
significantly diminished when Mg and Ti were galvanically coupled compared to when the two
metals were electrically disconnected. Next, the generation of reactive oxygen species (ROS)
increased when the Ti and Mg were galvanically coupled. Thus, although Ti usually exhibited
high corrosion resistance when exposed to physiological environments, an electrochemically
active surface was observed when galvanically coupled with Mg, and this surface may
participate in electron transfer reactions with chemical species in the neighboring environment;
this participation resulted in the increased pH values above its surface and enhanced generation
of ROS. These features contributed to the development of cytotoxic effects by galvanically
coupled Mg-Ti particles
60Co in Cast Steel Matrix: a European Interlaboratory Comparison for the Characterisation of New Activity Standards for Calibration of Gamma-ray Spectrometers in Metallurgy
International audience; Two series of activity standards of Co-60 in cast steel matrix, developed for the calibration of gamma-ray spectrometry systems in the metallurgical sector, were characterised using a European interlaboratory comparison among twelve National Metrology Institutes and one international organisation. The first standard, consisting of 14 disc shaped samples, was cast from steel contaminated during production ("originally"), and the second, consisting of 15 similar discs, from artificially-contaminated ("spiked") steel. The reference activity concentrations of Co-60 in the cast steel standards were (1.077 +/- 0.019) Bq g(-1) on 1 January 2013 12h00 UT and (1.483 +/- 0.022) Bq g(-1) on 1 June 2013 12h00 UT, respectively
Utilizing Knowledge of Physics in Safety Engineering
Any technician working in safety engineering needs certain knowledge of physics. This knowledge includes physical quantities and units of measurement, physical properties of substances, various formulae and equations, etc. It is also very important to possess knowledge enabling general - and often highly complex - processes to be simplified. This paper discusses two such possibilities for simplification