Acrylamide (AA) is one of the most common toxins in foods. Its
effect on bone microstructure has not been investigated. The aim
of our study was to analyze the impact of acute exposure to AA on
femoral bone microstructure in mice. Adult animals were treated
perorally with 2 doses of AA (E1 group, 1 mg/kg b.w.) in a 24-h
period and with 3 doses of AA (E2 group, 1 mg/kg b.w.) in a 48-h
period. Mice exposed to AA had smaller sizes of primary osteon's
vascular canals. Secondary osteons were significantly smaller in
mice from E2 group; however their increased number (from 38 %
to 77 %) was identified in both E1 and E2 groups. In these groups,
a higher number of resorption lacunae (from 100 % to 122 %) was
also found. The values for bone volume, trabecular number were
increased and that for trabecular separation was decreased in mice
administered AA. Significantly higher value of bone surface was
observed in mice from E1 group whereas trabecular thickness was
increased in E2 group. The effect of AA on microstructure of
compact and trabecular bone tissues is different. In our study, one
dose of AA was used and acute effects of AA were investigated.
Therefore, further studies are needed to study mechanisms by
which AA acts on bone.
Taurine, a sulphur - containing amino acid, has been termed
a functional nutrient. Its synthetic form is a common ingredient
in supplements and energy drinks. There is no information
concerning taurine impact on bone microstructure after
prolonged supplemental use. Also, differences in bone
parameters of mice following taurine exposure are unknown. In
this study, a detailed microstructure of compact and trabecular
bone tissues of mice subchronically exposed to taurine was
determined. Animals (n=12) were segregated into three groups:
E1 group – mice received 20 mg/kg b.w. of taurine per day
during 8 weeks; E2 group – mice were fed by taurine at a dose
of 40 mg/kg b.w. for 8 weeks and a control (C) group. Decreased
density of secondary osteons, increased sizes of primary osteon's
vascular canals (P<0.05) were observed in taurine – treated
animals. Cortical bone thickness, trabecular thickness were
decreased (P<0.05) in E1 group, and relative volume of
trabecular bone was lower (P<0.05) in E2 group as compared to
C group. According to our results, prolonged taurine exposure at
the doses used in this study can negatively affect both compact
and trabecular bone tissues microstructure.
Severe plastic deformation is one of the most effective methods of preparation of ultra-fine-structured materials with an extreaordinary combination of high strength and high ductility. The microstructure of these materials consists of sub-micrometer regions of misoriented crystal lattice. It is proposed that formation of the regions is a result of a tendency to decrease the internal energy opposed by a rearrangement of crystal lattice defects. The model of the structuralization process is formulated as an energy minimization problem.. and Obsahuje seznam literatury
The paper deals with the tire microstructures - microareas of the adhesive interfaces of steel cord - rubber. Namely attention is dedicated to degraded adhesive interfaces upon corrosion failure. The optical microscope is used for microscopy study of surfaces in the area of the adhesive interfaces of metal - rubber. Knowledge about degradation processes into microareas of the adhesive interfaces is important for process study of ultimate states of wear. Also knowledge about characteristic behaviour is possible to use in creation of complex computational models of tires. and Příspěvek se zabývá mikrooblastí adhezních vazeb ocelový výztužný kord - elastomer v pneumatikách z pohledu mikrostruktury. Pozornost je věnována zejména porušeným adhezním vazbám. Pro mikroskopické zkoumání adhezních vazeb kov - pryž je použit světelný mikroskop. Poznatky o iniciaci porušování adhezních vazeb jsou důležité pro studium procesu mezního stavu opotřebení. Znalosti o charakteristickém chování adhezních vazeb a změn materiálových struktur lze uplatnit při tvorbě komplexních výpočtových modelů pneumatik.
The microstructure of leaves and ultrastructure of chloroplasts were examined in tomato (Lycopersicon esculentum L.) plants treated with elevated temperature. Plants were exposed to 35°C for 30 d after florescence. The plants grown continuously under 25°C served as controls. Compared with the controls, the net photosynthetic rate (PN) in stressed plants decreased significantly. Stomatal conductance, intercellular CO2 concentrations, the rate of transpiration, and the limitation of stomatal conductance showed that the decrease in PN was caused mainly by nonstomatal restrictions. Meanwhile, stomata density increased significantly in the stressed plants. The stomata status of opening and closing became disorganized with a prolonged 35°C exposure. The damage of chloroplast membrane occurred earlier and was more serious in the plants under elevated temperature. At the same time, the thylakoids were loosely distributed with lesser grana, but the number of lipid droplets increased in chloroplasts. The number of starch grains in chloroplasts increased first and then decreased. In addition, the length of the main nerve in leaves increased and the main vein showed distortion in the plants stressed by 35°C. An increase was observed in the number of cells on the abaxial side of the main vein and these cells were overly congregated. The thickness of a vertical section became thinner in the stressed leaves. The cells of the upper epidermis thinned, and the ratio of palisade tissue to spongy tissue decreased. Generally, the photosynthetic apparatus of tomato changed significantly and the changed chloroplast ultrastructure might be one of the important reasons that caused the decrease of PN under 35°C., J. Zhang, X. D. Jiang, T. L. Li, X. J. Cao., and Obsahuje bibliografii
Laser technologies are among the unconventional methods of heat treatment and machining. Among the biggest advantages of laser quenching (hardening), it can be included high speed and process efficiency, a narrow thermally affected area and the possibility of processing complicated parts in shape that could not be workable with common conventional methods. During laser quenching of large surface parts, it is necessary to solve the problem of mutual overlap of laser spots. There is an unquenched area when insufficiently overlapped; with a large overlap, it can occur a tempering of the already quenched belt. Both cases negatively influence the resulting structure and mechanical properties. This article deals with finding the optimal degree of point laser spot overlap to ensure a high-quality quenching of large surface parts and with setting appropriate quenching parameters. and Laserové technologie se řadí mezi nekonvenční metody tepelného zpracování a obrábění. Mezi největší přednosti laserového kalení lze zařadit vysokou rychlost a efektivitu procesu, úzkou tepelně ovlivněnou oblast a možnostzpracování tvarově složitých součástí, které by běžnými konvenčními metodamizpracovatelné nebyly. Při laserovém kalení velkých plošných dílů je třeba vyřešit problém vzájemného překryvu laserových spotů. Při nedostatečném překryvu vzniká nezakalená oblast, při velkém překryvu může dojít k popuštění již zakaleného pásu. Oba případy negativně ovlivňují výslednou strukturu a mechanické vlastnosti. Tento článek se zabývá hledáním optimální míry překryvu bodových laserových spotů, aby bylo zaručeno kvalitní zakalení velkých plošných dílů, a nastavením vhodných kalicích parametrů.
Our study aimed to investigate subacute exposure to alcohol in relation to bone microstructure of mice. Animals from experimental (E) group drank a solution composed of 15 % ethanol and water for 14 days (one remodeling cycle), while those from control (C) group drank only water. In the compact bone of E group, decreased bone formation and increased porosity were observed which corresponds with lower levels of serum alkaline phosphatase and glutathione. Alcohol significantly increased sizes of primary osteon's vascular canals and decreased those of secondary osteons, Haversian canals. Relative bone volume, bone mineral density (BMD), relative bone volume without marrow cavity were also lower in E group. On the contrary, trabecular bone microstructure did not differ significantly between E and C groups. Liver function test showed higher levels of alanine aminotransferase, aspartate aminotransferase in alcohol-fed mice. Serum calcium, phosphate were significantly lower in E group. According to our study, only changes in compact bone microstructure of mice following one remodeling cycle were observed due to both direct and indirect effects of alcohol., A. Sarocka, V. Kovacova, R. Omelka, M. Bauerova, E. Kapusta, Z. Goc, G. Formicki, M. Martiniakova., and Obsahuje bibliografii