Electric field assisted remediation using nano iron has shown outstanding results as well as economic benefits during pilot applications (Černíková et al., 2020). This method is based on donating electrons to the zero-valent iron that possess an inherently strong reductive capacity. The reduction of chlorinated hydrocarbons may be characterized by a decrease in contaminants or better still by the evolution of ethene and ethane originating from the reduction of chlorinated ethenes. The evolution of ethene and ethane was observed predominantly in the vicinity of the anode despite reduction processes being expected near the cathode - the electron donor. The reduction near the anode occurred due to dissolved Fe2+ ions, whose presence was suggested by a Pourbaix diagram that combines Eh/pH values to characterize electrochemical stabilities between different species. No products of dechlorination were observed in the area of the cathode due to presence of oxidized Fe in the form of Fe3+ or Fe(OH)4-. The experimental work described in this research provides a deeper view of the processes of electrochemical reductive dechlorination using zero-valent iron and DC. It also showed an increase in the efficiency compared to the method using zero-valent iron only.
ISCO using activated sodium persulphate is a widely used technology for treating chlorinated solvent source zones. In sensitive areas, however, high groundwater sulphate concentrations following treatment may be a drawback. In situ biogeochemical transformation, a technology that degrades contaminants via reduced iron minerals formed by microbial activity, offers a potential solution for such sites, the bioreduction of sulphate and production of iron sulphides that abiotically degrade chlorinated ethenes acting as a secondary technology following ISCO. This study assesses this approach in the field using hydrochemical and molecular tools, solid phase analysis and geochemical modelling. Following a neutralisation and bioaugmentation, favourable conditions for iron- and sulphate-reducers were created, resulting in a remarkable increase in their relative abundance. The abundance of dechlorinating bacteria (Dehalococcoides mccartyi, Dehalobacter sp. and Desulfitobacterium spp.) remained low throughout this process. The activity of iron- and sulphate-reducers was further stimulated through application of magnetite plus starch and microiron plus starch, resulting in an increase in ferrous iron concentration (from
- MeSH
- chemické látky znečišťující vodu analýza metabolismus MeSH
- chlor metabolismus MeSH
- Chloroflexi metabolismus MeSH
- čištění vody metody MeSH
- Desulfitobacterium metabolismus MeSH
- ethyleny metabolismus MeSH
- halogenace MeSH
- oxidace-redukce MeSH
- Peptococcaceae metabolismus MeSH
- podzemní voda analýza chemie mikrobiologie MeSH
- regenerace a remediace životního prostředí metody MeSH
- rozpouštědla metabolismus MeSH
- sírany metabolismus MeSH
- sloučeniny sodíku MeSH
- tetrachlorethylen analýza metabolismus MeSH
- trichlorethylen analýza metabolismus MeSH
- železo metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
OBJECTIVE: More parameters have been used for more detailed description of mechanical properties of human hair as a fibre than in analogous studies. All measured samples were taken from five different locations on the heads of 60 women of varied age. METHODS: For each hair, the diameter was determined optically and then the test in the Deform Type 2 testing machine was carried out. Deformation curves were obtained by testing 10 mm long samples up to the rupture point at constant temperature, humidity and constant crossbar speed of 2 mm/min. The curves were processed with software for the calculation of mechanical parameters of the hairs. This specialized software has been designed by us for that purpose. Resulting values were arranged into tables and figures. RESULTS: As far as hair cross-section is concerned, it has been found that for the European population it appears to be rather higher - 86 μm - than indicated in formerly published texts. The 56 μm mentioned in the work of other authors has been observed only utterly exceptionally, in 0.3 % of the population. All quantities studied (except extensibility) display moderate to strong positive skewness in comparison to Gauss distribution. The most marked skewness is seen in the resilience. At the same time, this quantity displays the highest value of non-Gaussian distribution. The elasticity module of 2.3±0.6 GPa is three times lower than the one reported by other authors, yet according to the fact published in our work - which shows unambiguously that the thinner the hair, the higher elasticity module it displays - the value of 7.2 GPa for the 56 µm thick hairs is comparable and it confirms the hypothesis that the cortex, which is responsible for the mechanical strength of the hair, is contained in a higher ratio in thinner hairs. This similarly applies to the ultimate strength; the linearity limit is hard to compare with literature, as it almost does not appear there. CONCLUSION: By measuring 886 samples from the heads of 60 adult women of European type, it was possible to ascertain the current norm for a larger number of mechanical parameters of the hairs. Further merit of this work is the fact that the hairs were taken systematically from five well-defined places of the studied heads in equal count, which is an aspect formerly published works do not respect and they do not present the location of sampling.
- MeSH
- běloši MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mechanický stres * MeSH
- mladiství MeSH
- mladý dospělý MeSH
- pevnost v tahu fyziologie MeSH
- senioři MeSH
- vlasy, chlupy fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
OBJECTIVE: The human motion system reacts to both hypo and hyperactivity loads by changes to the rheological properties of tissues. This study deals with changes to the axial system (AS) compartment. Using the appropriate methodologies and mathematical-physical methods, these changes can be identified and quantified. METHODS: This study describes the noninvasive TVS (Transfer Vibration through Spine) method, which was applied to assess the AS selected mechanical properties in various modes. A pilot study was conducted on a top-level twelve-year-old girl-gymnast. The data detection was carried out in three cycles, before and after a peak 3.5 hour training session and the next day, after resting, just before the next training. RESULTS: Specifically, the values of selected rheological parameters, the AS damping coefficient b and viscosity μ, were obtained. The dynamics of their changes, in the stated load cycles, has also been shown. The damping coefficient b fell from the value of 0.626 to 0.324 before training and increased to 0.394 after resting. The viscosity coefficient μ showed a similar trend, namely falling from the value of 9.85 [Pa.s] to 2.15 [Pa.s] and then increasing to 3.8 [Pa.s] . CONCLUSIONS: With its computational solution, the TVS method,is a diagnostic apparatus making it possible to classify AS properties, both quantitatively and qualitatively, or its chosen segments and their changes, respectively. It can be used in classifying, preventing and treating the consequences of extreme motion and relaxing modes. The TVS application also makes it possible to control AS states over therapeutic, recovery, ergonomic and other loading modes of the human locomotion system.
- MeSH
- biomechanika MeSH
- dítě MeSH
- gymnastika * MeSH
- lidé MeSH
- páteř fyziologie MeSH
- pilotní projekty MeSH
- reologie * MeSH
- vibrace * MeSH
- viskozita MeSH
- zatížení muskuloskeletálního systému fyziologie MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
V našem experimentu jsme použili metodu TVS k detekci mechanických změn axiálního systému. Tyto mechanické změny mohou být podkladem pro pocit diskomfortu během monotónního zatížení během jízdy v automobilu. Metoda TVS je založena na aplikaci harmonického buzení plynule se měnícího od 5 Hz do 160 Hz na obratle C7 a L5. Toto vlnění se přenáší podél axiálního systému a akcelerometrickými snímači je snímáno zrychlení všech trnových výběžků obratlů, kterými se vlnění šíří mezi C7 až S1. Na základě naměřených dat lze vyhodnotit změnu mechanických vlastností páteře před a po hypokinéze a frekvenčním zatížení při jízdě v automobilu. Náš výzkum prokázal, že metoda TVS je vhodná pro detekci změn mechanických vlastností axiálního systému. Dále bylo prokázáno, že změny způsobené monotónním a frekvenčním zatížením ovlivňují způsob přenosu vlnění axiálním systémem subjektů. Z našich naměřených dat vyplývá, že můžeme subjekty srovnávat spíše intraindividuálně než interindividuálně. Zjistili jsme, že zdravá a flexibilní páteř osciluje jako elastická tyč a je schopna absorbovat více mechanické energie a spojení na páteři jsou více flexibilní. Rezonanční frekvence zdravé a flexibilní páteře se při našich měřeních objevuje mezi 40 a 60 Hz nebo výše. Ve většině případů nacházíme po jízdě v automobilu vyšší tlumení a nižší přenos vibrací. U některých subjektů se objevuje odlišná reakce na zatížení v hrudní a bederní páteři.
In our measurements, we used TVS method to detect mechanical changes of axial system. These mechanical changes can be base for discomfort feeling during monotonous driving in the car. The TVS method is based on the use of consequent application of continuously changing harmonic stimuli, which periodically differ between 5 Hz and 160 Hz, to the vertebrae C7 and L5. This wave is carried through the axial system and its acceleration on the spinous processes between C7 and S1 is scanned with the help of accelerometric sensors. According to the measured data, it is possible to identify changes of the mechanical properties of the human spine before and after applying hypo kinesis and frequency loading by the car ride. The research results proved the fact, that the TVS method is suitable for detection of the mechanical changes of axial system. It was also proved that changes caused by a monotonic and frequency loading influence the way of waves transfer through the axial system of the observed participants. From our data results, that we can compare the subjects more intraindividual than interindividual. We found out that healthy and flexible spine oscillates like elastic bar. It is able to absorb more mechanical energy with higher elasticity and the spinal joints are more flexible. The resonant frequency of the healthy and flexible spine lies between 40 and 60 Hz or higher. In most of the cases we found higher damping and lower transmission of the vibrations after the loading. By some of the subjects we can find different reaction in thoracic and lumbar spine to the loading.
OBJECTIVE: Hair quality and scalp characteristics are considered to be a significant marker of health. This marker is reflected in mechanical properties of hair. To investigate these properties, hair samples have been collected among women of different age and then analyzed. The thickness, Young's modulus of elasticity and ultimate strength limit were the main observed parameters. METHODS: The diameter of each hair has been measured using an optical microscope equipped with a digital camera. The hair was then clipped into the uniaxial tensile testing device. Each sample has been stretched to failure at a speed of 2 mm/min and force vs. elongation was recorded. The mechanical results were converted with respect to the diameter and Stress-Strain curve was obtained for each sample. In addition, all the analyzed samples were divided into two groups in dependence on the age, namely samples from women younger than 35 and over 35 years of age. All the measured parameters were statistically evaluated. RESULTS: Young's modulus, yield and elongation parameters showed no significant difference among samples. On the other hand there was a significant difference among the samples in ultimate strength values. Findings from group analysis showed that women under 35 years show about 5 times greater variability in hair strength than that of women above that age. CONCLUSION: The results of our study indicate that hair tendency to grow persists up to 30 years of age, then slowly decreases and then achieves a steady state around 60 years of age.
- MeSH
- biologické modely * MeSH
- dospělí MeSH
- elastografie MeSH
- lidé středního věku MeSH
- lidé MeSH
- mechanický stres MeSH
- pevnost v tahu fyziologie MeSH
- pružnost * MeSH
- stárnutí fyziologie MeSH
- vlasy, chlupy anatomie a histologie růst a vývoj fyziologie MeSH
- zdravotní stav * MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Klíčová slova
- Mechanická zátěž axiálního systému seniorů, Detekce přenosu mechanického vlnění axiálním systémem metodou TVS,
- MeSH
- bolesti zad diagnóza komplikace MeSH
- diagnostické techniky a postupy MeSH
- dospělí MeSH
- lidé MeSH
- muskuloskeletální systém * patofyziologie patologie MeSH
- poranění z opakovaného přetěžování patologie prevence a kontrola MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- stárnutí MeSH
- statistika jako téma MeSH
- vibrace škodlivé účinky MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- Publikační typ
- kazuistiky MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
The article encompasses a possible concept of description of the structure of hair thickness distribution over women's heads. It is based on real data realized in Caucasian population and results in the necessity of introduction of several type groups of women's heads coverage. With an example included, it eliminates the possibility of the distribution to be random and that there are all of the possibilities of the distribution realized in the population, as well as that it could be reasonable to average these distinct type groups and look for the mean distribution in the population. The distribution structure is most likely contingent on genetics and is entrenched in some part of the DNA; it is not yet clear however, what intra-species advantages particular structure types could yield, while the correlation of the particular distributions with types of humans is subject to current research.
- MeSH
- antropometrie * metody MeSH
- běloši genetika MeSH
- experimenty na lidech MeSH
- genetické jevy MeSH
- hlava MeSH
- lidé MeSH
- mikroskopie metody využití MeSH
- skalp * anatomie a histologie růst a vývoj MeSH
- statistika jako téma MeSH
- vlasy, chlupy * anatomie a histologie růst a vývoj MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- práce podpořená grantem MeSH
The conventional stoichiometry of the oxidation of elemental sulfur by ferric iron in Acidithiobacillus ferrooxidans was not in agreement with our experimental data in terms of ferrous iron and proton formation. Reaction modelling under the actual conditions of bacterial activity resulted in a different stoichiometry, where additional iron species participate in the process to affect the number of released protons. The suggested reaction equation may more accurately predict the intensity of environmental acidification during the anaerobic bioprocess.
- MeSH
- Acidithiobacillus metabolismus MeSH
- anaerobióza MeSH
- energetický metabolismus MeSH
- oxidace-redukce MeSH
- síra metabolismus MeSH
- železité sloučeniny metabolismus MeSH
- železnaté sloučeniny metabolismus MeSH
- železo metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
OBJECTIVES: During a longer car drive there are changes in rheological properties of driver's or passenger's connective tissues taking place as a consequence of monotonous and vibration load. These changes show more among the pregnant drivers, whose motion system is under heavier demands due to pregnancy. To asses these changes we have used the TVS (transfer vibration through the spine) method. METHODS: The TVS is based on application of γ excitation pulses with half-length 5 ms and then harmonic excitation continuously periodically changing from 5 Hz to 160 Hz on C7 and L5 vertebrae. This wave is transferred along the axial system and the acceleration of all the spinous tips of the vertebrae, along which the waves spread between C7 and S1, is detected by accelerometric sensors. The measurement was carried out on three drivers before and after a 4-hours driving. The same measurements of wave transfer along the spine with just one pregnant woman were carried out in th 16th, 26th and 32nd week of pregnancy. Consequently we constructed a simplified model of the spine in order to analyze gathered data by discovering elementary properties of the measured system. RESULTS: After both vibration and physical load there is a more significant dampening of the spinal tissues apparent, i.e. lower acceleration amplitude and the tissues resonance frequency also shifts towards the lower frequencies. On the other hand after long lasting relaxation on a bed an opposite tendency showed, the acceleration amplitude was higher, tissues were relaxed and dampening was lower. The same tendency manifested among the pregnant women. The influence of progressing pregnancy on the spinal segment transfer function showed through a shifting of peaks above 20Hz. Their size also changes monotonously. An absorption area moves towards higher frequencies, rigidity of axial system connections grows. CONCLUSION: The results say that drivers, including pregnant women, show changes in mechanical properties of examined tissues before and after vibration or other type of load. Or conversely before and after relaxation on a bed. Results of this work will be further analyzed, verified and evaluation procedures will be improved. We expect to find dependencies between excitation and resonance frequencies during the transfer via the axial system, the rheological properties of the axial system components and the physical nature of the load of the axial system. They are then going to be applicable for the prevention of injuries of the axial system, physiotherapy practices in the rehabilitation of post-operative conditions, the dosage of training loads of athletes, in determining the effects of job stress regimes and their prevention.
- MeSH
- biomechanika MeSH
- fyziologická adaptace MeSH
- fyziologický stres fyziologie MeSH
- lidé MeSH
- páteř fyziologie MeSH
- referenční hodnoty MeSH
- řízení motorových vozidel * MeSH
- studie případů a kontrol MeSH
- těhotenství fyziologie MeSH
- vibrace * MeSH
- zatížení muskuloskeletálního systému fyziologie MeSH
- Check Tag
- lidé MeSH
- těhotenství fyziologie MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
