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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Redukce korozních vrstev mosazi pomocí nízkotlakého nízkoteplotního plazmatu / Brass Corrosion Layers Reduction by Low-Pressure Low-Temperature Plasma

Řádková, Lucie January 2015 (has links)
This thesis presents results of the corrosion layers removal which could be found on the archaeological artefact surfaces. The low pressure low temperature plasma reduction was used for this purpose. Brass samples were chosen for this study. Two different ways have been used to form model corrosion layers. Several sets of corrosion layers were prepared in laboratory in two different corrosion atmospheres, namely ammonia atmosphere and atmosphere of hydrochloric acid. These samples were placed into desiccator. Small quantities of sand were added to some sets of samples so samples with sandy incrustation were prepared. The corrosion layers had been usually formed during four weeks. The second way, which was used to prepare model corrosion layer, was the natural corrosion in soil or compost. In this case, the corrosion layers had been formed approximately 2 years. The samples were treated in the low pressure (150 Pa) cylindrical Quartz reactor (90 cm long and 9.5 cm in diameter) with a pair of external copper electrodes connected via the matching network to a radiofrequency generator (13.56 MHz). The flows of working gases were set by independent mass flow controllers. Whole system was continuously pumped by the rotary oil pump which was separated from the discharge reactor by liquid nitrogen trap with aluminium chips eliminating dust and reactive species from the gas flow. Each sample was placed on a glass holder at the reactor center. Plasma was generated in pure hydrogen or in mixture of hydrogen and argon. Total flow of working gas was 50 sccm. Different ratios of gas mixture were tested, the ratio 30 sccm hydrogen and 20 sccm argon flows was the best. RF discharge was used in a continuous and pulsed regime. Pulsed mode was carried out with various duty cycle at the frequency of 1000 Hz. There were two ways of temperature monitoring. The sample temperature during the treatment was monitored by a K-type thermocouple installed inside the sample in the first case. Thermometer optical probe was connected to the sample surface by a small stainless plate and allowed continuous sample temperature monitoring in the second way. Safe object temperature for copper and copper alloys is 100–120 °C. To avoid exceeding this temperature, power control or the duty cycle in pulse mode were automatically controlled if thermometer optical probe was used. Plasma chemical treatment is based on generation of reactive atomic hydrogen in plasma discharge. The main reactions during reduction were reactions between oxygen and chloride contained in the corrosion layer and the hydrogen ions and neutral atoms generated in the plasma. These reactions create an unstable OH radical, which emits light in the region of 306–312 nm. This radiation was detected by the optical emission spectroscopy using Ocean Optics HR4000 spectrometer with 2400 gr/mm grating. Data obtained from this method were used to calculate rotational temperatures and integral intensity of OH radicals that were used for the process monitoring. Corrosion layer was not completely removed during the reduction, but due to the reactions which occur in the plasma corrosion layer became brittle and after plasma chemical treatment can be removed easily. The SEM-EDS material analyses were carried out before and after treatment of some samples. Some samples were analysed by XRD analysis. EDS analysis showed that amount of oxygen and chloride was decreased, mainly at 400 W pulse mode.
82

Masės pernešimo reiškiniai titano ant silicio padėklo dangose, oksiduotose vandens garų plazmoje / Study of mass-transport phenomena in titanium on silicon substrate films oxidized by water-vapor plasma

Vilkinis, Paulius 22 January 2014 (has links)
Darbe atlikta literatūros analizė šių procesų: (i) vykstančių vandens garų plazmoje; (ii) titano dangų oksidacija vandens garų plazmoje ir (iii) titano dioksido fotokatalitinės ir hidrofilinės savybės. TiO2 dangos buvo gautos po titano dangų ekspozicijos H2O garų plazmoje. Tyrimai parodė, kad TiO2 danga vandens garų plazmos aplinkoje formuoja elektrocheminį elementą. Darbe tirtos plazma aktyvuotos vandens skaldymo reakcijos. Parodyta, kad susidarę protonai pernešami per kietą TiO2 elektrolitą, o elektronai migruoja per plazmoje susiformavusią išorinę grandinę. Proceso metu dangos paviršinis sluoksnis formuojasi į TiO2–SiO2 kompozitą. Nors procesai vyksta žemoje temperatūroje, gauti rezultatai parodė masės pernešimo reiškinius, būdingus aukštoms temperatūroms. Pateikti nagrinėtų procesų mechanizmai. Darbo metu bandinių eksperimentinė analizė atlikta elektroninės dispersinės spektroskopijos (EDS), rentgeno spindulių difrakcijos (RSD), Auger elektroninės spektroskopijos (AES), skenuojančio elektroninio mikroskopo (SEM), optinės mikroskopijos ir kontaktinio profilometro metodais. / Processes in water vapor plasma, titania film oxidation in water vapor plasma and titanium dioxide photocatalytic and hydrophilic properties are discussed in this paper. Titatium dioxide thin films were obtained after titanium thin film exposure in water vapor plasma. Specimen together with H2O plasma forms electrochemical cell. In plasma film surface is activated and photocatalytic water splitting reactions occurs. Generated hydrogen ions are transported through solid titanium electrolyte and electrons are conducted to an external circuit via plasma. Titanium dioxide films surfaces are converted into composited composed of TiO2 and SiO2. Although oxidation process occurs in room temperature results showed mass transfer processes which occurs in high temperature. Specimens were analysed by electron dispersion spectroscopy (EDS), (X-ray diffraction (XRD), Auger electron spectroscopy (AES), glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), optical microscopy and nanoprofilometer methods.
83

Modelování interakce plazmatu s povrchy pevných látek / Modelling of plasma-solid interaction

Nožka, Jan January 2012 (has links)
Title: Modelling of plasma-solid interaction Author: Jan Nožka Department: Institute of Theoretical Physics Supervisor: prof. RNDr. Rudolf Hrach, DrSc., Department of Surface and Plasma Science Abstract: This work is devoted to computer modeling of the low-temperature argon plasma discharge. We created one basic particle model and one basic fluid model. Furthermore, we created a model of electron-electron interaction in three dimensions. This model is able to stabilize nonequilibrium electron gas in the expected equilibrium. This model was developed to investigate the influence of electron-electron scattering on the acceleration of electrons above the speed that is sufficient for excitation or ionization of neutral argon atom. At the end of this work there are results that shed a light on the importance of this interaction in comparison with the amount of fast electrons that are present in the plasma due to electric filed field.
84

UTICAJ SADRŽAJA PROTEINA U SPERMALNOJ PLAZMI NERASTA NA PARAMETRE RAZREĐENE SPERME I FERTILITET VEŠTAČKI OSEMENjENIH KRMAČA / Effect of protein content in the boar seminalplasma on the diluted semen parameters andfertility of artificially inseminated so

Apić Jelena 26 December 2015 (has links)
<p>Ve&scaron;tačko osemenjavanje (VO) je najznačajnija reproduktivna biotehnologija u<br />intenzivnoj proizvodnji svinja. Efikasan izbor visoko fertilnih genetski superiornih<br />nerastova i visok fertilitet ve&scaron;tački osemenjenih krmača, ima veliki ekonomski uticaj na<br />efikasnost praktične primene ove biotehnologije. Međutim, prethodna istraživanja<br />pokazuju da procena klasičnih parametara fertiliteta ejakulata (koncentracija, ukupan<br />broj, pokretljivost i morfologija spermatozoida) nisu dovoljni pokazatelji fertiliteta i<br />reproduktivne performanse nerastova. Sa druge strane, pokazalo se da je fertilitet<br />ve&scaron;tački osemenjenih krmača, često, niži od onog kod prirodno osemenjenih krmača.<br />Kao osnovni razlog nižeg fertiliteta kod VO krmača, navodi se osemenjavanje sa<br />prekomerno razređenim dozama i/ili dozama dugotrajno čuvanim (3 do 5 dana).<br />Rezultati prethodnih istraživanja ukazuju da komponente semene plazme imaju ključni<br />uticaj na fertilizacioni potencijal spermatozoida in vivo i in vitro, kao i na fiziolo&scaron;ke<br />procese važne za uspe&scaron;nu oplodnju i razvoj embriona u uterusu.<br />Zbog toga je glavni cilj ovog istraživanja bio da se: (a) odredi sadržaj proteina u<br />spermalnoj plazma nerastova koji se koriste za VO na nekoliko komercijalnih farmi<br />svinja u Srbiji, (b) oceni uticaj sadržaja proteina u spermalnoj plazmi na pokretljivost i<br />morfologija spermatozoida u nativnoj i razređenoj spermi, nakon 3 dana čuvanja u<br />razređenom stanju i (c) ispita uticaj intrauterine infuzije spermalne plazme, pre<br />aplikacije klasične VO doze, na fertilitet krmača.<br />Sadržaj proteina u spermalnoj plazmi se kretao između 1% i 6,5%, &scaron;to je<br />ustanovljeno kod 212 uzoraka, dobijenih iz ejakulata 106 nerastova, koji se koriste za<br />VO na 6 farmi u AP Vojvodini. Nizak nivo proteina (1-3.5%, prosečno 2,4%) je<br />ustanovljen kod 69%, a visok nivo proteina (3.6-6.5%, prosečno 4,2%) kod 31%<br />ispitivanih nerastova. Nije ustanovljen značajan (P&gt;0,05) uticaj rase ili starosti nerasta,<br />kao ni godi&scaron;nje sezone, na sadržaj proteina u spermalnoj plazmi. Citomorfolo&scaron;ka<br />svojstva spermatozoida su testirana sistemom CASA i protočnom citometrijom. U<br />nativnoj spermi testiranih nerastova, prosečno je bilo 71% živih, 13% spermatozoida sa<br />o&scaron;tećenim akrozomom i 32% spermatozoida sa morfolo&scaron;kim anomalijama. Volumen<br />ejakulata, koncentracija, ukupan broj i pokretljivost spermatozoida bili su značajno<br />(P&lt;0,01) veći kod nerastova sa visokim, u poređenju sa niskim sadržajem proteina u<br />spermalnoj plazmi. Progresivna pokretljivost - PP (64%) i broj živih spermatozoida - ŽS<br />(66%) bio je značajno veći, dok su broj spermatozoida sa o&scaron;tećenom ćelijskom<br />membranom - OM (19%), akrozomom - OA (29%) i hromozomima - OH (13%) bili<br />značajno (p&lt;0,01) niži u uzorcima sperme sa visokim sadržajem proteina, koji su bili<br />čuvani 72h u razređenju 1:4, od ovih vrednosti kod uzoraka sa niskim sadržajem<br />proteina (PP = 48%, ŽS = 44%, OM = 27% OA = 45% i OH = 22%). Zamena autologne<br />spermalne plazme iz ejakulata sa niskim sadržajem proteina od jednog nerasta, sa<br />homologom spermalnom plazmom iz ejakulata drugog nerasta sa visokim sadržajem<br />proteina, značajno (p&lt;0,01) povećava progresivnu pokretljivost spermatozoida, sa 52%<br />na 65%, kod uzoraka čuvanih 72h u razređenju 1:4. Intrauterina infuzija 30 ml semene<br />plazme, pre aplikacije klasične VO doze, značajno (p&lt;0,05) povećava vrednost<br />pra&scaron;enja (94%) i prosečan broj živo rođene prasadi po leglu (12.3) (p&lt;0,01), u<br />poređenju sa kontrolom grupom krmača (83% i 10.5 prasadi).<br />Na osnovu dobijenih rezultata, može se zaključiti: (1) postoje značajne razlike u<br />sadržaju proteina u spermalnoj plazmi između pojedinih nerastova, (2) uzorci sperme sa<br />visokim sadržajem proteina, imaju veće vrednosti fertilizacionog potencijala<br />spermatozoida, od uzoraka sa niskim sadržajem proteina u spermalnoj plazmi, posle 72h<br />čuvanja u razređenju 1:4 i (3) infuzija spermalne plazme, pre aplikacije klasične VO<br />iv<br />doze, značajno povećava fertilitet tako tretiranih krmača, u poređenju sa kontrolnim<br />krmača. Ovi rezultati pokazuju da određivanje sadržaja proteina u spermalnoj plazmi,<br />može biti korisno sredstvo za predviđanje stepena fertiliteta nerasta, pre njegove<br />upotrebe za VO, kao i da se spermalna plazma može koristi za povećanje fertiliteta<br />ve&scaron;tački osemenjenih krmača. Dobijenim rezultatima su, u potpunosti, potvrđene radne<br />hipoteze i ostvareni postavljeni ciljevi istraživanja.</p>
85

Inhibiny v reprodukci / Inhibins in reproduction

Babčová, Katarína January 2015 (has links)
Inhibin A and B participate to regulation of gametogenesis. We investigated their applicability as a marker of gametogenesis of men fertility disorders. We monitored the levels of inhibins during the treatment. We interested in their paracrine activity, relationship in sera, follicular fluid and seminal plasma depending on cause of fertility failure. We studied the levels of inhibin B in serum and seminal plasma from 355 men treated for fertility failure, in the context of their andrological and immunological findings (quality of spermiogrammes and acrosome area). We monitored concentration of levels of inhibin A and B in serum and follicular fluids depending on cause of fertility failure, on course and treatment outcome. We took blood samples in the time of the oocytes collection, of the embryotransfer and early pregnancy. The follicular fluids were obtained during the oocytes collection. The levels of both of inhibins were measured by ELISA in all medium (serum, follicular fluid, seminal plasma). We confirm, that inhibin B is useful marker of spermatogenesis in men, but is necessary to examine patient in complex with determination of immunology profile or quality of acrosome. Seminal plasma is, in some indicated cases, more suitable diagnostics material. Similarly inhibin B in women seems to be...
86

Studium vlivu stresových faktorů na fotosyntézu, vodivost průduchů a transpiraci brukve řepky olejky (Brassica napus L. var. napus) / Investigation of the impact of stress factors on photosynthesis and transpiration of rape (/Brassica napus /L. var./napus/)

BICANOVÁ, Laura January 2016 (has links)
The thesis deals with the influence of cold plasma treatment of seeds such as stress factor to the photosynthesis rate, transpiration and stomatal conductance of brassica oilseed rape (Brassica napus L. var. napus). The theoretical part is focused on the cold plasma, its application and effects on plant physiology, photosynthetic process and description of examined oilseed rape crops. The literature review is followed by the experiment which studies the influence of cold plasma on the physiological processes of plants. The seeds of oilseed rape have been treated with cold plasma in various intervals and cultivated plants were subjected to measuring device Licor Li 6400 XT. The results show that cold plasma treatment of brassica oilseed rape influences the physiological processes depending on the length of exposure and the plant age.
87

Vliv antiparazitálních koupelí ryb na hematologické a biochemické ukazatele / Influence of antiparasitic baths of fish on haematological and biochemical indicators

MECKO, Jozef January 2013 (has links)
The aim of the diploma thesis was to evaluate the influence of antiparasitic baths on selected biochemical and haematological parameters in the blood samples of fish. According to the results the application schema will be specified or amended such alterations will be substantiated. A test was performed on the fry of carp (naked and scaly form) to evaluate the influence of the peractetic acid with the help of biochemical and haematological parameters and with the histopathological examination. The common carp was exposed to the concetration 1 mg?l-1 and 2 mg?l-1 of PAA. Three days after application was taken the blood samples from fish and the biochemical and haematological parameters were determined. Than was taken a sample of skin with the musculature from fish to be sent for the histopathological examination in University of Veterinary and Pharmaceutical Sciences in Brno. Based on the results the naked form of the carp has been declared to be more sensitive to the application of PAA. All the observed changes in haematological and biochemical parameters were within physiological range, so it can be stated, that the application schema of PAA has not a signifiant negative influence on the health of the tested fish.
88

Numerické simulace MHD vln v neutrální proudové vrstvě / Numerical simulations of MHD waves at a neutral current-sheet

ZEMAN, Zdeněk January 2013 (has links)
The subject of this thesis is the numerical simulation of magneto hydro dynamic waves in the neutral current layer. In the first part, attention is described to the description of basic characteristics and Sun. The next section describes introduction to the theory of MHD equations suitable for solution of wave propagation in a neutral current layer. Then we deal with the numerical simulations of fast magnetoacoustic waves in the neutral current layer. The last section is devoted to the results obtained, their analysis and conclusion.
89

Využití plazmové trysky pro biomedicínské aplikace / Use of plasma jet for biomedical application

Doubravová, Anna January 2020 (has links)
This master´s thesis is focused on the utilization of the sterilization effects of low temperature plasma towards the bacterial microorganisms that occur mainly on the human skin. The plasma sterilization process is fast efficient, non-toxic, environmentally friendly, cost-effective and safe for the operating staff as well as for the patient. Another advantage of using low temperature plasma is to support cell proliferation and wound healing. By combining these advantages, an effective method can be obtained, which would sterilize the wounds sparingly with regard to the surrounding healthy tissue and support the regeneration of the damaged tissue at the same time. In the experimental part, gram positive and gram negative bacteria were used to prove the sterilization effects with respect to different cell wall structure. Staphylococcus epidermidis and Propionibacterium acnes, which cause purulent skin inflammations, were used as gram-positive microorganisms. Serratia marcescens and Escherichia coli were selected from gram positive bacteria. These model organisms were inoculated at various concentrations on culture broths and treated by plasma at a distance of 1 mm from the agar surface. The microwave discharge was generated in argon at a power of 9 W, a gas flow rate of 5 l / min and water cooling to avoid thermal effects on the treated surface. Subsequently, model skin cells of HaCaT were exposed to low temperature plasma and tested for plasma cytotoxicity to demonstrate its healing effects. The obtained results make it possible to state that the sterilizing effects of low-temperature plasma in all tested gram-positive and gram-negative bacterial strains are verified in this work. Finally, tests were demonstrated using a suitable method of the treatment on human skin cells, where the safety and usefulness of the tested low-temperature plasma was demonstrated when applied to shorten the healing process.
90

Depozice wolframových vrstev pomocí technologie RF-ICP / RF-ICP deposition of tungsten coatings

Zlatník, Rostislav January 2020 (has links)
The main object of this work is the technology of radio frequency controlled inductively coupled plasma, abbreviated RF-ICP. The specific goal of the work was the application of surface layers of tungsten and analysis of the influence of changes in process conditions on the resulting microstructure and chemical composition of deposited coatings. The monitored conditions were torch power, choice of carrier gas, powder feedrate.

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