HARDNESS OF NITRIDED LAYERS TREATED BY PLASMA NITRIDING

Stainless steels, particularly the austenitic stainless grades are widely used in many industries due to good corrosion resistance, but very poor mechanical properties as surface hardness and wear resistance limit its possible use. Plasma nitriding is one of the few ways to increase the surface hardness of these steels, even though this will affect its corrosion resistance. This paper focuses on the description of the mechanical properties of nitrided layers in the two most widespread austenitic stainless steels AISI 304 and AISI 316L. The microstructure and properties of nitrided layers were evaluated by metallography and microhardness measurement. Surface properties of nitrided steels were characterized by Martens hardness. The results show that plasma nitriding created very hard nitrided layers with thickness about 40 μm and microhardness about 1300 HV0.05. Surface hardness measurements have shown that the maximum values for both steels are about 8.5 GPa, but have different behaviour under higher loads, when the AISI 316L nitrided layer began to crack on the surface and sink

Wireless Video Capsule Enteroscopy in Preclinical Studies: Methodical Design of Its Applicability in Experimental Pigs

The aim of this project was to develop a methodology to introduce wireless video capsule endoscopy in preclinical research. Five mature female pigs (Sus scrofa domestica) were selected for the study. Capsule endoscopes (the EndoCapsule system; Olympus) were introduced into the duodenum endoscopically in each of the animals. The life span of batteries (i.e., total time of endoscopy recording) was 487–540 min (median 492 min). The capsule endoscope reached the cecum during enteroscopy once (after 7 h 57 min), in the remaining cases, endoscopy recordings terminated in the distal or terminal ileum. All capsule enteroscopies found a normal pattern of the small intestine. The intestinal lumen is narrower, transverse folds are sparse or even absent, villi are wider but less prominent in pigs compared to humans. Capsule endoscopy in experimental pigs will be helpful for future trials on injury of different drugs and xenobiotics to the small bowel

Effect of boron and vanadium addition on friction-wear properties of the coating AlCrN for special applications

Cutting tools have long been coated with an AlCrN hard coating system that has good mechanical and tribological qualities. Boron (B) and vanadium (V) additions to AlCrN coatings were studied for their mechanical and tribological properties. Cathodic multi-arc evaporation was used to successfully manufacture the AlCrBN and AlCrVN coatings. These multicomponent coatings were applied to the untreated and plasma-nitrided surfaces of HS6-5-2 and H13 steels, respectively. Nanoindentation and Vickers micro-hardness tests were used to assess the mechanical properties of the materials. Ball-on-flat wear tests with WC-Co balls as counterparts were used to assess the friction-wear capabilities. Nanoindentation tests demonstrated that AlCrBN coating has a higher hardness (HIT 40.9 GPa) than AlCrVN coating (39.3 GPa). Steels’ wear resistance was significantly increased by a hybrid treatment that included plasma nitriding and hard coatings. The wear volume was 3% better for the AlCrBN coating than for the AlCrVN coating on H13 nitrided steel, decreasing by 89% compared to the untreated material. For HS6-5-2 steel, the wear volume was almost the same for both coatings but decreased by 77% compared to the untreated material. Boron addition significantly improved the mechanical, tribological, and adhesive capabilities of the AlCrN coating. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Department of Mechanical Engineering, University of Defence in Brno [SV20-216]; Project for the Development of the Organization "DZRO Military autonomous and robotic systems"; Slovak Research and Development AgencySlovak Research and Development Agency [APVV-15-0710]Agentúra na Podporu Výskumu a Vývoja, APVV: APVV-15-071

Přístavba domu na parcele č.2 v Hlučíně

Import 22/06/2007Prezenční226 - Katedra architektur

Ad fontes, a small hydropower plant for own consumption

Tato bakalářská práce se zabývá návrhem domácí vodní elektrárny. První část je postavena na teoretické bázi a je věnována vodní energii, rozdělení vodních elektráren a částem nezbytným k jejich provozu. Druhá část je zaměřena prakticky a je určena ke konkrétnímu návrhu domácí vodní elektrárny. Obsahuje popis objektu Oparenského mlýna v současném stavu, objasňuje legislativní požadavky na povolení vodní stavby.Hlavní úsek druhé části se zabývá technickým řešením návrhua osvětlení funkce jednotlivých komponentů. Poslední část nastiňuje finanční rozvahu včetně návratnosti nákladů na realizaci projektu.This bachelor thesis deals witha design of a home hydropower plant. The first part is built on a theoretical basis and it is devoted to water energy, the classification of hydropower plants and the parts necessary for their functionality. The second part is focused on the practical design of the home hydropower plant. It contains a description of the Oparno Mill in its present condition, clarifying the legislative requirements for the approval of the home hydropower plant. The main part of the second portion deals with the technical design solution and explanation of the used components functions. The last part presents the financial balance sheet, including the return-on-investments on the project realization costs

2250 Improving the properties of unburned earth to control the interior microclimate

The article concerns the problematics of unburned earth used as material for moulding formwork or clay plaster with lowered contraction, especially about interior unburned earth plaster with the heightened percentage of clay and therefore improved sorption abilities. By adding a plasticizer, it is possible to modify the fluidity of the mixture. With lessening the amount of water it is possible to lower the shrinkage. Furthermore, we can increase the ratio of clay to sand and thus we can control the indoor microclimate. This is because the clay provides adsorption properties. Unburnt clay has been widely used as a building material in the past around the world. In the last century, this material was rather despised. Nowadays, however, this trend is reversing and the unburnt clay is experiencing a renaissance. Increasingly people emphasize ecology, a healthy and balanced indoor climate, and demand buildings with low operational and energy intensity. All this can be offered by unburnt clay, because it is energy-efficient in production, easily accessible in almost all parts of the world, harmless, and beneficial to human health, as clay can contribute to the improvement of the internal microclimate to a much greater extent than other building materials, as confirmed by many scientific findings

Low-Complexity Decentralized Active Damping of One-Dimensional Structures

In the paper, we propose distributed feedback control laws for active damping of one-dimensional mechanical structures equipped with dense arrays of force actuators and position and velocity sensors. We consider proportional position and velocity feedback from the neighboring nodes with symmetric gains. Achievable control performance with respect to stability margin and damping ratio is discussed. Compared to full-featured complex controllers obtained by modern design methods like LQG, H-infinity, or mu-synthesis, these simplistic controllers are more suitable for experimental fine tuning and are less case-dependent, and they shall be easier to implement on the target future smart-material platforms

Caco-2 Cells, Biopharmaceutics Classification System (BCS) and Biowaiter

Almost all orally administered drugs are absorbed across the intestinal mucosa. The Caco-2 monolayers are used as an in vitro model to predict drug absorption in humans and to explore mechanism of drug absorption. The Caco-2 cells are derived from a human colon adenocarcinoma and spontaneously differentiate to form confluent monolayer of polarized cells structurally and functionally resembling the small intestinal epithelium. For studying drug permeability, Caco-2 cells are seeded onto the Transwell inserts with semipermeable membrane and grown to late confluence (21 days). After determination of cell viability, the integrity of monolayer is checked by phenol red permeability and by 14C-mannitol permeability. The transport from apical to basolateral (AP-BL) and basolateral to apical (BL-AP) is studied by adding the diluted drug on the apical or basolateral side and withdrawing the samples from the opposite compartment, respectively, for HPLC analysis or liquid scintillation spectrometry. Ca2+- free transport medium is used to determine paracellular component of the drug transport. On the basis of permeability and solubility, drugs can be categorized into four classes of Biopharmaceutics Classification System (BCS). For certain drugs, the BCS-based biowaiver approach can be used which enables to reduce in vivo bioequivalence studies

New insights into gene positional clustering and its properties supported by large-scale analysis of various differentiation pathways

AbstractTo understand how genes are distributed on chromosomes we bring new insights into gene positional clustering and its properties. We have made a large-scale analysis of three types of differentiation and we observed that genes that subsequently enter into different cell processes are positionally clustered on chromosomes. Genes from the clusters are transcribed subsequently with respect to time kinetics and also to position. This means that the genes related to a cellular process are clustered together, independent of the period of time during which they are active and important for the process. Our results also demonstrate not only that there are general regions of increased or decreased levels of gene expression, but also that, in fact, in some chromosome regions we can find clustering of genes related to specific cell processes. The results provided in this paper also support the theory of “transcription factories” and show that transcription of genes from the clusters is managed by softer epigenetic mechanisms