Search results for "ZnO"
showing 10 items of 264 documents
Photoassisted Oxidation of the Recalcitrant Cyanuric Acid Substrate in Aqueous ZnO Suspensions
2007
The photoassisted oxidative transformation of the highly recalcitrant cyanuric acid was examined in the liquid−solid regime at pH 3 and natural pH 7.5 under UV irradiation in oxygen- and ozone-saturated ZnO suspensions using ZnO as a photomediator. Loss of cyanuric acid was assayed by HPLC UV absorption spectroscopy, whereas intermediates and final products were determined by HPLC ion chromatography (IC), by MS techniques using an electrospray ionization mass spectrometer operated in the negative-ion mode, and by FT-IR spectroscopy. Final reaction products were CO2 gas and NO3- ions. The measure of nitrate in solution quantified the degree of mineralization of the substrate; its concentrati…
GROWTH AND PHOTOELECTROCHEMICAL BEHAVIOUR OF ELECTRODEPOSITED ZnO THIN FILMS FOR SOLAR CELLS
2012
Thin zinc oxide films were deposited potentiostatically from zinc nitrate aqueous solutions on ITO substrates. The influence of experimental parameters (temperature, electrolyte concentration, deposition potential) on structure and morphology of films was investigated. Deposited films were generally polycrystalline in structure, even if growth according to preferential planes occurs in certain conditions. The effect of thermal treatments in air at 150 and 350 °C was also studied. In some cases, Cl species were incorporated into deposit by adding zinc chloride to the electrolyte. A photoelectrochemical investigation, performed in neutral solution before and after thermal treatment, gives mor…
ZnO nanorod arrays fabrication via chemical bath deposition: Ligand concentration effect study
2010
A new ligand, N, N, N', N'-tetramethylethylenediamine, has been used to grow ZnO nanorods on silicon substrates via a two steps approach. A preliminary seeding on silicon substrates has been combined with chemical bath deposition using a Zinc acetate - N, N, N', N'-tetramethylethylenediamine aqueous solution. The used diamino ligand has been selected as Zn(2+) complexing agent and the related hydrolysis generates the reacting ions (Zn(2-) and OH(-)) responsible for the ZnO growth. The seed layer has been annealed at low temperature (<200 degrees C) and the ZnO nanorods have been grown on this ZnO amorphous layer. There is experimental evidence that the ligand concentration (ranging from 5 t…
Gleznošanas ietekme uz pareiza satvēriena izveidi
2019
Martas Roģes kvalifikācijas darba tēma ir „Gleznošanas ietekme uz pareiza satvēriena izveidi”. Darba autore izvēlējās šo tēmu, jo uzskata, ka tas ir svarīgs priekšnoteikums, lai tiktu sekmīgi apgūta zīmēšana, gleznošana un pirms tiek uzsāktas skolas gaitas arī rakstīšana. Kvalifikācijas darba teorētiskajā daļā tika aplūkoti un analizēti dažādi svarīgi, ar satvērienu saistīti jautājumi un meklēti risinājumi izmantojot dažādus literatūras avotus. Praktiskā pētījuma laikā tika veiktas pārrunas ar bērniem, uzdodot jautājumus saistībā ar tēlotājdarbību, precīzāk, saistībā ar darbu, kurā izmanto guaša krāsas un otu, lai izprastu, kādas ir bērnu intereses konkrētajā jomā. Papildus pārrunām darba a…
Zvaigžņotā Debess: 2010/11, Ziema (210)
2010
Contents: “ZVAIGŅOTĀ DEBESS” FORTY YEARS AGO: Bursting Stars. J. Francman (abridged). Geodesists Help Renew the Spire of St. Peter’s Church. J. Klētnieks (abridged). DEVELOPMENTS in SCIENCE: The Solar Neutrino Problem. O. Smirnova. NEWS: At Last the Planet at the Star β Pictoris Is Imaged. A. Alksnis, Z. Alksne. SPACE RESEARCH and EXPLORATION: The Trail of an Asteroid Reveals a Recent Collision. A. Alksnis. INTERNATIONAL YEAR of ASTRONOMY 2009: International Year of Astronomy 2009 in Philately. The Rest of the World except Series EUROPA (concluded). J. Limansky. ACADEMIC STAFF of the UNIVERSITY of LATVIA: Assistant Professor in Physics Ojārs Šmits (24.04.1930.-14.03.1993.) of the Latvian Un…
Magnetotransport Studies of Encapsulated Topological Insulator Bi2Se3 Nanoribbons
2022
This research was funded by the Latvian Council of Science, project “Highly tunable surface state transport in topological insulator nanoribbons”, No. lzp-2020/2-0343, and by the European Union’s Horizon 2020 research and innovation program, Grant Agreement No. 766714/ HiTIMe. Institute of Solid-State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.
ZnxCd1-xO polikristālisko plāno kārtiņu iegūšana un īpašības
2015
Cinka oksīdu, kadmija oksīdu un to cietos šķīdumus mēģina plašāk pielietot elektronikā, pateicoties to fizikālajam īpašībām. Uz to bāzes ražo dažādas heterostruktūras un heteropārejas, kuras ir galvenās sastāvdaļas starojuma avotos un detektoros. Šajā maģistra darbā ir apkopota informācija par cinka oksīda, kadmija oksīda un to cieto šķīdumu kārtiņu iegūšanas metodēm, aprakstītas šo materiālu galvenās īpašības. Darba praktiskajā daļā parādītas jaunās ekstrakcijas-pirolītiskās metodes iespējas ZnO-CdO plāno kārtiņu iegūšanai uz stikla un kvarca pamatnēm. Paraugu raksturošanai izmanto rentgenstaru difrakcijas un skenējošo elektronu mikroskopiju. Daļai kārtiņu nosaka arī biezumu. Iegūtās kārti…
Multifunctional halloysite and hectorite catalysts for effective transformation of biomass to biodiesel
2023
Halloysite surface was modified with tetrabutylammonium iodide, and then the obtained nanomaterial was used as support for ZnO nanoparticles. After characterization, the nanomaterial was used as a catalyst for fatty acid methyl esters (FAMEs) production. The recyclability of the nanomaterial was also investigated, and the optimization of reaction conditions by the design of experiments approach was performed as well. In addition, the synthesized nanomaterial was tested as a catalyst for FAME production from a series of waste lipids affording biodiesel in moderate to good yields (35–95%), depending on the matrix. To fully exploit the feasibility of clay minerals as catalysts in biodiesel for…
Integration of Metal Organic Chemical Vapour Deposition and Wet Chemical Techniques to Obtain Highly Ordered Porous ZnO Nanoplatforms
2011
Large-area, highly ordered ZnO micropores-arrays consisting of ZnO nanotubes delimited by ZnO nanorods have been successfully fabricated and tested for protein sensing applications. ZnO seed layers have been deposited by Metal Organic Chemical Vapour Deposition and readily patterned by Colloidal Lithography to attain ZnO nanorods growth at selective sites by Chemical Bath Deposition. The used synthetic approach has been proven effective for the easy assembly of ZnO nanoplatforms into high-density arrays. Both patterned and unpatterned ZnO nanorods have been morphologically and compositionally characterised and, thus, tested for model studies of protein mobility at the interface. The pattern…
In Situ Study of Zinc Peroxide Decomposition to Zinc Oxide by X‐Ray Absorption Spectroscopy and Reverse Monte Carlo Simulations
2022
The authors wish to thank Dr. R. Kalendarev for the synthesis of ZnO2 sample. A.K. would like to thank the financial support of the ERDF Project No. 1.1.1.1/20/A/060. The experiment at the MAX IV synchrotron was performed within the project 20190823. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.