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Wyświetlanie 1-5 z 5
Tytuł:
Balance control of children and adolescents suffering from vertigo symptoms: in what way posturography is helpful in clinical evaluation of vestibular system pathology?
Autorzy:
Szczerbik, Ewa
Iwanicka-Pronicka, Katarzyna
Syczewska, Małgorzata
Kalinowska, Małgorzata
Graff, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/306568.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dzieci
zawroty głowy
test równowagi
children
vertigo
balance
stable surface
Opis:
The aim of the study was to determine balance parameters in a group of young patients with vertigo symptoms and to verify posturography helpfulness in clinical evaluation of vestibular system pathology. Methods: 77 children and adolescents of age 3–18 suffering from vertigo episodes participated in the study (46 girls, 31 boys). They underwent audiology objective tests and balance test on stable surface. Calculated balance parameters were analyzed in reference to: eyes opened and closed, age influence, sway comparison in anterior-posterior and medial-lateral, differences between subgroups with and without vestibular deficits. Discriminant analysis was performed to assess classification ability to impaired group in two cases: only balance parameters and both audiology and balance parameters. Results: Patients with vertigo symptoms generally keep their balance properly on stable surface. Balance parameters do not depend on presence of vestibular system pathology. Values increased in eyes closed conditions. Left/Right and Anterior/Posterior differences were not statistically significant. The negative correlation between age and some balance parameters is present, stronger in the case of eyes opened and weaker or absent in vestibular impaired group. Also, correlations between axes were found, higher in impaired group in comparison with not impaired one. Conclusions: Discrimination based on balance parameters is poor not comparable to one built on combined: audiology and balance parameters, so typical balance parameters’ analysis is not so useful in clinical practice when the reason of vertigo episodes should be assessed, but verify compensation process and measure with objective numbers the progress of recovering, the actual functional patient’s status.
Źródło:
Acta of Bioengineering and Biomechanics; 2019, 21, 1; 73-78
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancement of Life Time of the Dimensionally Stable Anode for Copper Electroplating Applications
Autorzy:
Son, S. H.
Park, S. C.
Lee, M. S.
Powiązania:
https://bibliotekanauki.pl/articles/356684.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
dimensionally stable anode
surface treatment
life time
copper
electrodeposition
Opis:
In order to enhance the long-term stability of DSA for copper electroplating process, in the present study, noble metal oxides with excellent electrochemical properties was used and optimum condition was determined the ratio of noble metal oxides, surface pre-treatment of titanium substrate and heat treatment. The effect of the surface pretreatment of titanium substrate and ratio of noble metal oxides were estimated by accelerated test at the highly current density conditions. The lifetime of DSA increase six-fold higher as the oxide thickness of Ta 7 : Ir 3 composition ratio. Under the optimal condition, surface pretreatment led to dramatic increase in the lifetime of DSA.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1019-1022
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface treatment for improvement of coefficient of friction on sliding surfaces
Autorzy:
Tanabe, I.
Soe, Y. H.
Iyama, T.
Powiązania:
https://bibliotekanauki.pl/articles/99784.pdf
Data publikacji:
2012
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
tribology
friction
micromachine
laser machining
surface treatment
DLC
stable behavior
Opis:
Recently, many micro structure products are used for compact, high precision and others functions in the field of measuring instruments, medical instruments, information processing devices and so on. However, in the small sliding parts of these products, the surface contact pressure becomes lowered and then, higher adhesive force occurs, resulting larger coefficient of friction. On the other hand, in the field of machine tools, lubrication free sliding parts are also demanded for eco-friendly. In this study, the surface treatment for improvement of coefficient of friction for both light load and heavy load applications are investigated. When laser ray is applied on stainless steel surface, CrO2 layer with small concaves like dimple is generated. This CrO2 layer is used in light load applications. Next, TiAlN and DLC coating are being used on cutting tools for reducing coefficient of friction and cutting heat. Therefore, these coating materials are used for heavy load and oil free applications. The improvement of coefficient of friction and life of coating are investigated by experiments. It was concluded from the results that; (1) Coefficient of friction for light load application can be reduced by coating CrO2 layer. (2) Coefficients of friction for heavy load application were reduced by coating TiAlN and DLC layer. (3) Life of both CrO2 and DLC layers are sufficiently long for practical applications at light load and heavy load respectively.
Źródło:
Journal of Machine Engineering; 2012, 12, 1; 7-17
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface geochemical survey at Starunia palaeontological site and vicinity (Carpathian region, Ukraine)
Autorzy:
Sechman, H.
Kotarba, M. J.
Dzieniewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/191493.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
surface geochemical survey
stable carbon isotopes
methane origin
gaseous hydrocar bon C2-C5
carbon dioxide origin
woolly rhinoceros
Starunia
Carpathian region
Ukraine
Opis:
A surface geochemical survey was carried out in an abandoned ozokerite mine in Starunia, where remnants of a mammoth and three woolly rhinoceroses and one almost completely preserved rhinoceros carcass were found in 1907 and 1929. In total, 689 measurement sites were defined within the selected 300×350 m rectangle (ca. 10.5 ha). The analysed soil gases vary in their molecular and isotopic compositions. Several zones with anomalous methane concentrations over 10 vol% were identified in the study area. These anomalous concentrations correlate well with total C2-C5 alkane anomalies (over 1 vol%). The zones with carbon dioxide concentrations over 15 vol% are generally shifted SW of those, where the methane and the sum of C2-C5 alkanes anomalies were identified. High helium concentrations of crustal origin (over 0.001 vol%) are clustered near fault zones. In a majority of cases methane is of thermogenic origin, migrating to the near-surface zone from deep-seated accumulations. Microbial methane, or methane with a high microbial component, is genetically related to recent swamps. The high variability of concentrations of gaseous components together with the highly variable isotopic composition of individual gases in the soil, indicate their thermogenic and/or microbial origin, and point to the lithological diversity of Quaternary sediments in the study area. Several zones with thermogenic gaseous hydrocarbons and helium were delineated. It is likely that during the Pleistocene winters, under a thick ice and snow cover, the tundra lake and swamp zones around outflows of brines, oil, helium and thermogenic gases had a higher temperature, which resulted in melting and cracking of the ice cover. These sites would be more prospective for future search of well-preserved large vertebrates.
Źródło:
Annales Societatis Geologorum Poloniae; 2009, 79, No 3; 375-390
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distribution and origin of gaseous hydrocarbons and carbon dioxide in the Quaternary sediments at Starunia palaeontological site and vicinity (Carpathian region, Ukraine)
Autorzy:
Kotarba, M. J.
Sechman, H.
Dzieniewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/191503.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
near-surface geochemical survey
depth gas distribution
stable carbon isotopes
gaseous hydrocarbon origin
carbon dioxide origin
Quaternary sediments
woolly rhinoceros
Starunia palaeontological site
Ukrainian Carpathians
Opis:
Near-surface gases were investigated in Starunia, where remains of mammoth and woolly rhinoceroses were discovered at the beginning of the 20th century. Samples were collected at 30 measurement sites, from 0.8, 1.6, 2.4, 3.2 and 4.0 m depths and analysed for their molecular and isotopic compositions. Most of the methane and all higher gaseous hydrocarbons accumulated within the near-surface zone are of thermogenic origin. The distribution of thermogenic methane and higher gaseous hydrocarbons in Quaternary sediments is variable and, generally, increases with depth. Microbial methane or a mixture of microbial and thermogenic methane also occurs at the near-surface zone. The presence of hydrogen and alkenes in the near-surface gases also suggests a contribution from recent, microbial processes. Helium of crustal origin migrated through the Rinne Fault and other tectonic zones located in the study area, and was subsequently dispersed during migration through the lithologically diversified Pleistocene and Holocene sediments. The high variability of the carbon dioxide concentration and stable carbon isotope composition at various depths in the near-surface zone is caused by its polygenetic origin (thermogenic, microbial, and oxidation of hydrocarbons and Quaternary organic matter), and also by its dissolution in water and oil during migration through lithologically diversified Pleistocene and Holocene sediments. Zones of thermogenic methane occurrence within Pleistocene sediments, dominated by muds saturated with bitumen and brines, provide the most favourable environment for preservation of large extinct mammals. It is likely that during the Pleistocene winters, when thick ice and snow covered the tundra lake and swamp, zones of outflow of brines, oils, helium, and thermogenic gaseous hydrocarbons had a higher temperature, which could have resulted in melting and cracking of the ice cover and drowning of large mammals. The most favourable conditions for preservation of large, extinct mammals probably still exists in the vicinity of sampling probe sites Nos 21, 22, 23 and 36. Zones of dominance of microbial methane concentrations are less favourable sites for preservation of extinct mammals, because this methane was generated within recent swamps and also within recent descending meteoric waters which infiltrated into Pleistocene and Holocene sediments. Older Pleistocene microbial gases have already escaped to the atmosphere.
Źródło:
Annales Societatis Geologorum Poloniae; 2009, 79, No 3; 403-419
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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