42 research outputs found
Corrosion resistance of heat-treated Ni-W alloy coatings
The paper presents research on evaluation of corrosion resistance of Ni-W alloy coatings subjected to heat treatment. The corrosion resistance was tested in 5% NaCl solution by the use of potentiodynamic polarization technique and electrochemical impedance spectroscopy. Characteristics of the Ni-W coatings after heat treatment were carried out using scanning electron microscopy, scanning Kelvin probe technique and X-ray di raction. Suggested reasons for the improvement of properties of the heat treated Ni-W coating, obtained at the lowest current density value (125 mA cm2), are the highest tungsten content (c.a. 25 at.%) as well as the smallest and the most homogeneous electrochemically active surface area
The age of peak performance in women and men duathletes - The paradigm of short and long versions in ‘Powerman Zofingen’
Novel organic material induced by electron beam irradiation for medical application
This study analyzed the e ects of irradiation of polytetrafluoroethylene (PTFE) containing 40% of bronze using an electron beam with energy of 10 MeV. Dosages from 26 to156 kGy (2.6–15.6 Mrad) were used. The impact of a high-energy electron beam on the thermal, spectrophotometric, mechanical, and tribological properties was determined, and the results were compared with those obtained for pure PTFE. Thermal properties studies showed that such irradiation caused changes in melting temperature Tm and crystallization temperature Tc, an increase in crystallization heat DHc, and a large increase in crystallinity c proportional to the absorbed dose
for both polymers. The addition of bronze decreased the degree of crystallinity of PTFE by twofold. Infrared spectroscopy (FTIR) studies confirmed that the main phenomenon associated with electron beam irradiation was the photodegradation of the polymer chains for both PTFE containing bronze and pure PTFE. This had a direct e ect on the increase in the degree of crystallinity observed in DSC studies. The use of a bronze additive could lead to energy dissipation over the additive particles. An increase in hardness H and Young’s modulus E was also observed. The addition of bronze and the irradiation with an electron beam improved of the operational properties of PTFE
Atrial Fibrillation in Athletes—Features of Development, Current Approaches to the Treatment, and Prevention of Complications
Atrial fibrillation (AF) is one of the most common types of cardiac arrhythmias. This review article highlights the problem of the development of atrial fibrillation in individuals engaged in physical activity and sports. Predisposing factors, causes, and development mechanisms of atrial fibrillation in athletes from the perspective of the authors are described. Methods of treatment, as well as prevention of thromboembolic complications, are discussed. Directions for further studies of this problem and prevention of complications are proposed
Evaluation of Structure and Corrosion Behavior of FeAl Alloy after Crystallization, Hot Extrusion and Hot Rolling
The paper presents the results of tests on the corrosion resistance of Fe40Al5Cr0.2TiB alloy
after casting, plastic working using extrusion and rolling methods. Examination of the
microstructure of the Fe40Al5Cr0.2TiB alloy after casting and after plastic working was performed
on an Olympus GX51 light microscope. The stereological relationships of the alloy microstructure
in the state after crystallization and after plastic working were determined. The quantitative analysis
of the structure was conducted after testing with the EBSD INCA HKL detector and the Nordlys II
analysis system (Channel 5), which was equipped with the Hitachi S-3400N microscope. Structure
tests and corrosion tests were performed on tests cut perpendicular to the ingot axis, extrusion
direction, and rolling direction. As a result of the tests, it was found that the crystallized alloy has
better corrosion resistance than plastically processed material. Plastic working increases the
intensity of the electrochemical corrosion of the examined alloy. It was found that as-cast alloy is
the most resistant to corrosion in a 5% NaCl compared with the alloys after hot extrusion and after
hot rolling
New kind of polymer materials based on selected complexing star-shaped polyethers
In today’s analytical trends, there is an ever-increasing importance of polymeric materials for low molecular weight compounds including amines and drugs because they can act as carriers or capture amines or drugs. The use of this type of materials will allow the development of modern materials for the chromatographic column beds and the substrates of selective sensors. Moreover, these kinds of materials could be used as a drug carrier. Therefore, the aim of this study is presenting the synthesis and complexing properties of star-shaped oxiranes as a new sensor for the selective complexation of low molecular weight compounds. Propylene oxide and selected oxirane monomers with carbazolyl in the substituent were selected as the monomers in this case and tetrahydrofuran as its solvent. The obtained polymer structures were characterized using the MALDI-TOF. It was found that in the initiation step potassium hydride deprotonates the monomer molecule and takes also part in the nucleophilic substitution. The resulting polymeric material preferably cross-linked with selected di-oxiranes (1,2,7,8-diepoksyoktan in respect ratio 3:1 according to active center) was then used as a stationary phase in the column and thin layer chromatography for amine separation and identification. Sorption ability of the resulting deposits was determined using a quartz microbalance (QCMB). The study was carried out in stationary mode and flow cells to simulate actual operating phase conditions. Based on changes in electrode vibration frequency, the maximum amount of adsorbed analyte and the best conditions for its sorption were determined
Editorial: Kinesiophobia – psychological aspects of physical activity in breast cancer patients
Tribological and Mechanical Behavior of Graphite Composites of Polytetrafluoroethylene (PTFE) Irradiated by the Electron Beam
This research investigated the e ect of irradiation with an electron beam energy of
10 MeV in doses of 26–156 kGy on polytetrafluoroethylene (PTFE) with a 15% and 20% graphite
additive. The research has shown that mechanical (compression strength, hardness, and Young’s
modulus) and sclerometric (coe cient of wear micromechanism and coe cient of resistance to
wear) properties improve and tribological wear decreases as graphite content increases. Electron
beam irradiation increases the degree of crystallinity of both materials to a similar extent. However
significant di erences in the improvement of all examined properties have been demonstrated for
PTFE with higher (20%) graphite content subjected to the electron beam irradiation. This polymer
is characterized by higher hardness and Young’s modulus, reduced susceptibility to permanent
deformation, higher elasticity, compression strength, and above all, a nearly 30% reduction in
tribological wear compared to PTFE with a 15% graphite additive. The most advantageous properties
can be obtained for both of the examined composites after absorbing a dose of 104 kGy. The obtained
results hold promise for the improvement of the operational life of friction couples which do not
require lubrication, used for example in air compressors and engines, and for the possibility of
application of these modified polymers. In particular PTFE with 20% graphite content, in the nuclear
and space industry
The influence of chlorine in indoor swimming pools on the composition of breathing phase of professional swimmers
Objectives: Swimming is one of the most popular forms of physical activity. Pool water is cleaned with chlorine,
which - in combination with compounds contained in water - could form chloramines and trichloromethane in the
swimmer’s lungs. The aim of the present study was to examine the effect of swimming training in an indoor pool on
the composition of swimmers’ respiratory phase metabolomics, and develop a system to provide basic information
about its impact on the swimmer’s airway mucosa metabolism, which could help to assess the risk of secondary
respiratory tract diseases i.e. sport results, condition, and health including lung acute and chronic diseases).
Design: A group of competitive swimmers participated in the study and samples of their respiratory phase before
training, immediately after training, and 2 h after training were assessed.
Methods: Sixteen male national and international-level competitive swimmers participated in this study. Respiratory
phase analysis of the indoor swimming pool swimmers was performed. Gas chromatography combined with mass
spectrometry (GCMS) was used in the measurements. All collected data were transferred to numerical analysis for
trends of tracking and mapping. The breathing phase was collected on special porous material and analyzed using
GCMS headspace.
Results: The obtained samples of exhaled air were composed of significantly different metabolomics when
compared before, during and after exercise training. This suggests that exposition to indoor chlorine causes
changes in the airway mucosa Conclusion: This phenomenon may be explained by occurrence of a chlorine-initiated bio-reaction in the
swimmers’ lungs. The obtained results indicate that chromatographic exhaled gas analysis is a sensitive
method of pulmonary metabolomic changes assessment. Presented analysis of swimmers exhaled air indicates,
that indoor swimming may be responsible for airway irritation caused by volatile chlorine compounds and
their influence on lung metabolism