The paper focuses on investigating the effect of impregnation of recycled concrete aggregate on the mechanical and durability properties of concrete using this aggregate. Cement paste, limewater and diluted water glass were used to impregnate the aggregate. Both a single impregnation and a double impregnation using two different solutions were carried out. A total of four groups of concrete series, with two values of w/c ratio (0.45 and 0.60), were made. Concrete made using the impregnated aggregate was tested and the results were compared with those of concrete made using untreated recycled aggregate of the same kind. The results indicate that impregnation of aggregate improves the mechanical properties of concrete in many cases but reduces its resistance to cyclic freezing and thawing. Furthermore, in the case of impregnation with two solutions, the order in which the impregnants are applied influences the effect obtained. Using the results received, the impregnation methods were ranked in order from best to worst. The best impregnation method proved to be with cement paste, followed by diluted water glass, while the worst results were obtained with limewater, followed by diluted water glass.

• Klíčová slova
• compressive strength, concrete durability, freeze-thaw cycles, impregnation, recycled concrete aggregate,
• Publikační typ
• časopisecké články MeSH

This paper describes the early stages of impregnation by the Golgi method. Sections of aldehyde-fixed and potassium dichromate-treated cerebral cortex were mounted on glass slides and cover slipped. The dichromate solution was replaced by silver nitrate solution and events in the section were followed and recorded by time lapse microphotography and video recording until stopped by replacement of silver nitrate solution by glycerol. The sections were subsequently prepared for electron microscopy (EM) study. In sections about 2 x 2 mm and 100 microns thick a fine, dark granular precipitate formed at the edges within the first minutes of exposure to silver nitrate and a wave of brownish colouration spread to a depth of about 0.3 mm. After approximately 7 min, shrub-like focal precipitates (nucleation centres) appeared in the sections. From these nucleation centres (but also from the section edges) thread-like 'outgrowths', usually identified as dendrites, spread into somata. Sometimes impregnation began within the soma and spread into dendrites. The rate of impregnation (i.e., of silver chromate deposition within dendrites) was typically 1-7 microns min-1, faster in the earlier stages (up to 3 microns s-1) and very slow after 30 min, by which time many neurons were more or less fully impregnated. The dimensions of the section, the width of an agar frame around the sections, and the frequency with which the silver nitrate in the sections was replenished all affected the extent and time course of the impregnation. By EM the earliest intracellular deposits consisted of tubulolamellar formations which did not cross plasma or endocellular membrane boundaries and which contained irregularly shaped and scattered granules, initially about 10 nm in diameter. The latter progressively enlarged and coalesced as the tubulolamellar formations extended, eventually to fill the cross-sectional area of neuronal processes and cell bodies. These observations shed light on why so few neurons become impregnated with the Golgi method. Impregnation occurred only in those cells a part of which was within a nucleation centre.

• MeSH
• barvení a značení * MeSH
• dendrity ultrastruktura   MeSH
• histologické techniky * MeSH
• lidé MeSH
• mozková kůra ultrastruktura   MeSH
• myši MeSH
• neurony ultrastruktura   MeSH
• stříbro * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• stříbro * MeSH

Additive manufacturing offers great potential for various industrial solutions; in particular, the binder jetting method enables the production of components from various materials, including sand molds for casting. This work presents the results of an extensive set of experiments aimed at enhancing the structural strengthening of 3D-printed sand molds. Structural strengthening was achieved by impregnating the sand-printed structures with two polymer materials: epoxy resin and silicone varnish. Impregnation was performed with variable parameters, such as temperature, pressure, and time. Structural strengthening using polymers was investigated by analyzing the flexural strength and impact resistance of the impregnated products and comparing these obtained values with the reference material in terms of impregnation parameters and the polymer used. Microstructural observations and an analysis of the pore filling were also performed. This approach allowed for a full assessment of the influence of processing parameters and the type of polymer used for impregnation on the properties of sand-printed structures, which allowed for identifying the most optimal method to be used to strengthen the sand molds for casting the components for electrical devices. As a direct proof of concept, it was shown that impregnation with polymeric materials could effectively strengthen the sand mold, increasing its flexural strength and impact resistance by over 20 times and 5 times, respectively. A full-scale mold was printed using binder jetting, impregnated with epoxy resin at 65 °C, and used to successfully fabricate a fully functional electrification device.

• Klíčová slova
• additive manufacturing, polymer impregnation, sand mold, structural strengthening,
• Publikační typ
• časopisecké články MeSH

This paper describes the early stages of impregnation by the Golgi rapid method in sections and blocks of brain tissue. Aldehyde-fixed and potassium dichromate-treated sections of cerebral cortex were placed on glass slides and coverslipped. The dichromate solution was then replaced by a silver nitrate solution, and events taking place in the section were monitored and time-lapse recorded until the impregnation was interrupted and the sections subsequently prepared for electron microscopy. The tissue blocks, fixed and chromated in the same way, were placed into a silver nitrate solution for 30 min to 24 h and the progress of impregnation compared with the results obtained in the sections on the glass slides. Two basic modes of impregnation were observed, apparently in direct relation to the process of crystallization of silver chromate: crystals of silver chromate growing directly from the surface of the tissue into the nerve cell via its transected plasma membranes, and microcrystalline precipitate of silver chromate spreading into the nerve cell from nucleation centres dispersed in the tissue. The precipitate grows inside the cell as in a preformed channel until the cell has been filled. If the nucleation begins extracellularly, the precipitate extends into the narrow intercellular gaps. Electron microscopy showed that the crystalline precipitate consisted of multilamellar formations containing dense coalesced granules that did not cross plasma or endocellular membrane boundaries.

• MeSH
• barvení stříbrem metody   MeSH
• dusičnan stříbrný MeSH
• dvojchroman draselný MeSH
• elektronová mikroskopie MeSH
• krysa rodu Rattus MeSH
• krystalizace MeSH
• lidé MeSH
• mozek ultrastruktura   MeSH
• myši MeSH
• neurony ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dusičnan stříbrný MeSH
• dvojchroman draselný MeSH

Marking excision margins of surgical specimens by silver impregnation has several advantages over commonly used Indian ink: during the slicing the tissue preserves its natural color, the staining is permanent, and the pigment does not smudge over cutting surfaces. The pigment is clearly visible in tissue sections. The tissue specimen is shortly dipped into a 10% water solution of argent nitrate (AgNO3 with HNO3). After slicing, the tissue specimens are developed in common black & white developer for several seconds and paraffin processed as usual. The method is suitable for formaldehyde fixed as well as fresh tissue specimens.

• MeSH
• barvení stříbrem metody   MeSH
• lidé MeSH
• nádory patologie   chirurgie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Pt, Ru, and Ir were introduced onto the surface of graphitic carbon nitride (g-C3N4) using the wet impregnation method. A reduction of these photocatalysts with hydrogen causes several changes, such as a significant increase in the specific surface area, a C/N atomic ratio, a number of defects in the crystalline structure of g-C3N4, and the contribution of nitrogen bound to the amino and imino groups. According to the X-ray photoelectron spectroscopy results, a transition layer is formed at the g-C3N4/metal nanoparticle interphase, which contains metal at a positive degree of oxidation bonded to nitrogen. These structural changes significantly enhanced the photocatalytic activity in the production of hydrogen through the water-splitting reaction. The activity of the platinum photocatalyst was 24 times greater than that of pristine g-C3N4. Moreover, the enhanced activity was attributed to significantly better separation of photogenerated electron-hole pairs on metal nanoparticles and structural distortions of g-C3N4.

• Klíčová slova
• graphitic carbon nitride, metal photocatalysts, photocatalytic activity, physicochemical characterization, wet impregnation method,
• Publikační typ
• časopisecké články MeSH

The Gallyas' method based on impregnation of endothelial basal lamina and reticulin fibres, allowing to reveal the microcirculatory bed, was used to demonstrate the angioarchitecture of brain and spinal cord tumours. This technique, for the first time, enables a more complex view on tumours tissue microvascular architecture than previously. Using of thick paraffin sections enables to incorporate this method into the set of routine diagnostic histology.

• MeSH
• barvení a značení * MeSH
• cévy patologie   MeSH
• gliom krevní zásobení   MeSH
• histologické techniky MeSH
• lidé MeSH
• nádory mozku krevní zásobení   MeSH
• nádory páteře krevní zásobení   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH

• MeSH
• chromozomy MeSH
• dimethylsulfoxid MeSH
• fibroblasty * MeSH
• glycerol MeSH
• karyotypizace * MeSH
• lyofilizace MeSH
• myši MeSH
• uchovávání tkání MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dimethylsulfoxid MeSH
• glycerol MeSH

• MeSH
• barvení a značení metody   MeSH
• cystická fibróza patologie   MeSH
• dusičnan stříbrný * MeSH
• histocytochemie MeSH
• lidé MeSH
• pankreas cytologie   MeSH
• stříbro MeSH
• vývody pankreatu cytologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dusičnan stříbrný * MeSH
• stříbro MeSH

The authors present their experience on Gallays' silver staining of vascular basal lamina--especially of microcirculary bed--in human and rat brain and spinal cord. They pointed out that the quality of impregnation was strongly influenced by a duration of formol fixation and pyridine senzibilization. When using sections of equal thickness they demonstrated this method offers a more complex angioarchitectonic pattern then India ink injection in vessels' lumina. More over the so called intercapillary bridges including their dynamics, origin and regression are uniquely revealed by this method.

• MeSH
• barvení stříbrem MeSH
• centrální nervový systém krevní zásobení   MeSH
• cévní endotel cytologie   MeSH
• histologické techniky * MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• mikrocirkulace cytologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH