Ultrasound exfoliation of inorganic analogues of graphene

High-intensity ultrasound exfoliation of a bulk-layered material is an attractive route for large-scale preparation of monolayers. The monolayer slices could potentially be prepared with a high yield (up to 100%) in a few minutes. Exfoliation of natural minerals (such as tungstenite and molybdenite) or bulk synthetic materials (including hexagonal boron nitride (h-BN), hexagonal boron carbon nitride (h-BCN), and graphitic carbon nitride (g-C(3)N(4))) in liquids leads to the breakdown of the 3D graphitic structure into a 2D structure; the efficiency of this process is highly dependent upon the physical effects of the ultrasound. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were employed to verify the quality of the exfoliation. Herein, this new method of exfoliation with ultrasound assistance for application to mono- and bilayered materials in hydrophobic and hydrophilic environments is presented

Improvement of Orange II Photobleaching by Moderate Ga 3+

Highly photoactive Ga3+-doped anatase modification of titania was prepared by homogeneous hydrolysis of aqueous solutions mixture of titanium oxo-sulphate TiOSO4 and gallium(III) nitrate with urea. Incorporation of Ga3+ into the anatase lattice has a clear positive effect on the photocatalytic activity under UV and Vis light irradiation up to a certain extent of Ga. Ga3+ doping decreased the size of the crystallites, increased surface area, and affected texture of the samples. Higher amount of gallium leads to the formation of a nondiffractive phase, probably photocatalytically inactive. The titania sample with 2.18 wt.% Ge3+ had the highest activity during the photocatalysed degradation in the UV and visible light regions; the total bleaching of dye Orange II was achieved within 29 minutes. Ga concentration larger than 5% (up to 15%) significantly inhibited the growth of the anatase crystal domains which formed the nondiffractive phase content and led to remarkable worsening of the photobleaching efficiency

Mesoporous silica matrices derived from sol-gel process assisted by low power ultrasonic activation

The present work contributes to elucidating the differences between silica gels obtained by low doses ultrasonic activation, and those obtained by the conventional method, termed as classical sol gel. Silica matrices were produced by sol-gel synthesis process, assisted and non-assisted by an ultrasonic field, and subsequently characterized by various methods. Nitrogen adsorption and small-angle neutron scattering (SANS) measurements provided texture and microstructure of the dried gels. The adsorption results show that the sample sonicated for 2 hours presents the most ordered microstructure, characterized by pore shape close to spherical and the narrowest size distribution – about 90 % of the pores for this sample fall into the mesopore range (2–50 nm). SANS data reveal the formation of primary structural units of sizes around 1.5–2 nm which are small linear or branched polymeric species of roughly spherical shape and with rough surface. They are generated in the very early stage of sol gel process, as a result of hydrolysis and condensation reactions. The aggregated primary units form the secondary porous structure which can be described as a rough surface with fractal dimension above 2. The best porosity characteristics were obtained for the sample activated for 2 hours, indicating the optimal doses of sonication in the present conditions. Our results demonstrate the possibility of tailoring the pore size distribution using a low power ultrasonic bath

Barrier Type Pigments for Corrosion Protection

Alignment natural pigments specularite (.alpha. - Fe2O3 - "ferric mica") with the pigments based on modify mica. Mica flakes (muscovite) of particles size 20-80 nm were covered with layers Fe2O3 about thickness 1 nm by homogenous precipitation of f

Nanodispersive mixed oxides and hydroxides prepared alkaline titanate methods

Nanodispersive mixed oxides and hydroxides prepared alkaline titanate methods

Pigments based on mica coated with oxides of metals

Mica pigment with oxide-hydroxide layer of different metals, such as Ti, Cr, Fe, Al, Co, Ni, Zn, and Cu. Mica coloured flakjes were covered by homogeneous precipitation of metal sulphates with urea in an aqueous environment at temperatures 95-98 grad C

Photoactive Titanium Oxide - Perspective Pigments for 3rd Millenary

Titania powders, widely used in industrial application as pigments, opacifiers, photocatalysts and fillers have been obtained either directly from titanium-bearing minerals or by precipitation from solutions of titanium salts or alkoksides

Preparation of special inorganic pigments using hydrolysis of salts with urea in aqueous solutions

Práce je zaměřena na přípravu a charakteristiku produktů připravených homogenním srážením anorganických solí ve vodném prostředí močovinou. Připravené produkty byly charakterizovány metodami RTG difrakční analysy, mikroskopickými metodami, termoanalytickými metodami, měrným povrchem a porositou. Aplikace homogenního srážení lze využít při přípravě pigmentů, pigmentů na bázi modifikované slídy, fotokatalyzátorů a nanodispersních látek pro rozklad bojových otravných látek.Katedra anorganické technologieDokončená práce s úspěšnou obhajobo

Implementation of the Tournament Coding method for compression of integer sequences

Hlavním cílem této bakalářské práce je implementace nestatistické kompresní metody pro kódování číselných posloupností. V teoretické části je Tournament kódování důkladně popsáno a analyzováno. Praktická část je zaměřena na efektivní implementaci metody. Jedním z požadavků na metodu je schopnost zakódovat posloupnosti řádu 10^8 prvků. Implementace je navržena s ohledem na minimální paměťovou náročnost. Metoda byla porovnána s běžně používanými kompresními metodami. Pro srovnání bylo zvoleno Huffmanovo, aritmetické a Fibonacciho kódování. Metody byly testovány na posloupnostech s normálním, exponenciálním, rovnoměrným a Laplaceovým rozdělením.Katedra informatiky a výpočetní technikyObhájenoThe main goal of this bachelor thesis is the implementation of the non-statical coding technique for compression of integer sequences. In the theoretical part of this thesis Tournament coding is thoroughly described and investigated. The practical part is focused on efficient implementation of this method. One of requirements for the method is the ability of sequence coding up to the 10^8 of elements. The implementation is proposed regard to minimal memory demand. The method has been compared to commonly used compression methods. Huffman, arithmetic and Fibonacci coding have been chosen for the comparison. Sequences with uniform, exponential, Laplace and normal distribution have been used for testing