Papers by Keyword: Microscopy

Abstract: Collisions between vehicles and pedestrians are a significant problem, and substantial evidence indicates that the problem is closely linked with low illumination. A less expensive approach to enhancing the conspicuity of pedestrians involves using retroreflective material – material that has been engineered to passively reflect light back in the direction of its source. In a Textile faculty of TU Liberec was developed microscopic method to research the affecting factors textile thin bands retroreflectivity [1]. This work has been done through the use of several quality tools allowing studying different phenomena such as effect of color and technology on retroreflectivity levels.

Abstract: The present work deals with determination of the cause of crack occurring in a part of car body manufactured from deep-drawing sheet. UHR-SEM, EDS, EBSD and measurement of microhardness were used for evaluation of the structure, local deformation and crack formation mechanism. A material analysis discovered foreign particles in the material. These particles were identified as MgAl2O4 with BCC lattice. The occurrence of these hard particles led to local stress concentration, decrease in mechanical strength and sheet breach due to tensile stress during deformation.

Abstract: The purpose of this study has been to identify and emphasise structural and ultrastructural modifications occurring in the vaginal epithelium in ovariectomised female rats, as well as their reactivity to the administration of injectable oestrogens. 30 female Wistar white rats have been used, with an average weight of 200 g, distributed as follows: group 1, control group, with no treatment or intervention whatsoever, group 2, menopausal, operated group, with no treatment, and groups 3, 4 and 5, operated, to which oestrogenic treatment was administered. 15 days after surgery, the hormone replacement therapy with injectable oestrogens was initiated (Estradiol, Estradurin, Sintofolin), with a dosage of 0.2 mg/rat/day, and after 14 days of treatment, all animals were sacrificed and biopsies were taken from vaginal epithelium, after which the samples were processed in accordance with optical microscopy techniques (the semi-thin section technique) and transmission electron microscopy (TEM). In group 2, the vaginal epithelium was congested and exhibited relatively numerous invaginations of the mucosa and irregularities of the surface of the epithelium, with a decrease in the number of cells forming every layer, including the ones in the basal layer, which could no longer ensure the regeneration of all cells lost at the level of the epithelium of the superficial layer. In groups 3, 4 and 5, compared to group 2, ovariectomised, the semi-thin sections obtained revealed hyperplasia of all cellular layers of the vaginal epithelium. Ultrastructural investigations confirm the results of the structural study based on semi-thin sections, as the injectable oestrogen treatment has protected and rebuilt the structure of the vaginal epithelium, the chorion and the muscular layers affected by ovariectomy. Our study has shown that experimentally induced menopause has caused significant modifications, expressed polymorphically with alterations to various degrees of ultrastructural visualisation at the level of the entire vaginal epithelium. In all groups treated with oestrogens, it has become apparent that the vaginal epithelium is hyperplased, with the vast majority of its cells having a normal or almost normal aspect, and an isolated presence of structures that have not been completely rebuilt.

Abstract: Tibial fractures were, still are and will be a challenge for the orthopedic surgeon. In this paper we conducted a case study on a system plate-screw made by titanium that was used in clinical practice for reduction and fixation of a tibial pilon fracture. After eight months the patient returns for the ablation of metallic implants. Clinical and strengthen the fracture callus is found radiologic hypertrophic and degradation plaque.On retrieved plate were made following investigations in order to establish the causes that lead to the failure: determining the chemical composition through spectral analysis, macrostructural analysis using stereomicroscopy, microstructure analysis using optical microscope metallographic, and fractographic analysis using scanning electron microscopy. Complex analysis of the fracture surfaces of the locking plate has led to the ultimate conclusion that the material has been made self-locking plate is inadequate chemical purity satisfactory embedding, which has led to breakage within an area of ​​non-homogeneous structure. Breaking looks fragile behaviour by transgranular cleavage with sharp facets. There were also highlighted intergranular cracks between planes of cleavage sides.

Abstract: Currently orthopedics challenge is the use of intramedullary nails to straighten diaphyseal femoral fractures. In this paper it was conducted a case study on an intramedullary nail used for femoral fracture stabilization, in the case of one young patient. The evolution was unfavorable to the fracture site and the implant failed after three month of first surgical intervention. Intramedullary nail dimensions were 300mm length and 10mm in diameter. The following investigations were made in order to establish the failure causes: determination of the chemical composition through spectral analysis, macrostructural analysis using stereomicroscopy, optical microstructural analysis using optical microscopy, fractographic analysis using scanning electron microscopy. The final conclusions showed that the metallic biomaterial used for manufacturing the intramedullary nail was approximately an austenitic stainless steel AISI 316L, but with major microstructural defects. Macro-structural analysis revealed the presence of two zones of cracking, which are very rare at austenitic stainless steels. Also breaking with a fragile character has radial front tear propagation. In longitudinal section, cracks were evidenced due to the extraction operation and also the presence of corrosion products was shown. From fractographic analysis it was determined that intramedullary nail failure was predominantly through the mechanism of brittle fracture that took place at the point of maximum bending of the implant fragile.

Abstract: Measuring of the non-elastic deformation of wide range of materials under extreme environments, such as high temperature, underwater or lack of space, is described in this paper. Method, called Predictive Instant Defect Analysis of Constructions for short PIDAC, is based on precise indication of defined distance change between two points before and after loading. Distance is mechanical imprinted into an indication specimen and consequently measured by microscopy analysis. The technology solves not only problem of measuring plastic length deformations but also offers the capability of predicting catastrophic failure due to the breaking, tearing, or deforming of materials.

Abstract: Mimosa Pudica (also known as Pokok Semalu) is an action plant with unique biological cell mechanism that has great potential to be explored for next generation biomechatronics devices. The motion principle of each petiole movement occurs by an organ of motion, called pulvinus. The behavior analysis of the Mimosa Pudica plant main pulvinus and petiole against external stimulations has been investigated. The response of the plant cell was observed by optical and scanning electron microscopes (SEM). External stimulation tests on Mimosa Pudica plant such as mechanical, electrical and light stimulations were conducted. Optical microscopy and SEM observations revealed the existence of red cells in the tertiary pulvinus. Mechanical stimulation results had shown a response time of approximately 2 seconds and a recovery time of 10 to 12 minutes for the leaves and 20 minutes for the petiole. Bending force of the petiole of Mimosa Pudica was also measured. The torque generated by the bending of petiole was found to increase exponentially as the pulvinus diameter increased. A torque of 30.91 g mm was generated from the bending of a petiole with 1.5 mm pulvinus diameter. The lifting potential of the Mimosa Pudica was tested using loadings with increments of 0.42 gram. The plant responded to electrical stimulation of 1.3 Ampere and displayed side effect. The light sensitivity region of Mimosa Pudica was obtained through light stimulation using a full spectrum daylight bulb, and ranges from 50 to 300 lux. Signal transmission to neighbouring structures was observed when the leaf was stimulated with threatening stimulus, with the signal speed achieving 0.8 cm/s. Movement mechanism of Mimosa Pudica is believed to be triggered by signal through receptor cells. It was found that the torque generated during petiole lifting is relatively higher than that during petiole bending.

Abstract: different types of incenses are burnt during religious ceremonies in churches: frankincense, myrrh or rosin based incense. The icons from iconostasis usually are not protected by glass and they are exposed to the burning products of incense. To study the influence of burnt frankincense, myrrh and rosin based incense artificial on different types of dammar varnishes, samples of balsa wood covered with gesso, titanium white and dammar varnish were exposed to incense and were artificial aged under UV-A light for 60 hours. This paper presents the colour changes suffered by the varnishes.

Abstract: Conventional concrete does not have durability and higher strength as produced by high performance concrete (HPC). It is known that the HPC possess the following three properties which are high workability, high strength, and durability. The introduction of polycarboxylate ether (PCE) superplasticizer was proved to enhance the workability of concrete even though at a lower water to cement ratio. The study was conducted to find the optimum dosage of PCE and to compare its compressive strength, physical characteristics and morphology of the HPC. The result of the test shows that the high performance concrete (HPC) with addition of 0.5% polycarboxylate ether (PCE) superplasticizer of the cement mass have the highest compressive strength and excellent physical properties.

Abstract: The paper demonstrates that indirect testing performed with thermal microscopy facilities can be used successfully to study the properties of heat-resistant added metal.