THE ANALYSIS OF CAUSES OF LORRY PISTON COMBUSTION ENGINE DAMAGE

<div><p>The article deals with analysis of causes of lorry piston combustion engine damage. For docummentation and analysis of causes was used macroscopical, microscopical and scanning electron microscopy. The analysis showed that the reason of fatal damage resides in production process of lorry combustion pistons which proved in implication of fatigue damage and subsequent burnout in two piston place.<em> </em></p> <p><em> </em></p></div

Effect of Heat Treatment on the Resulting Dimensional Characteristics of the C45 Carbon Steel after Turning

The presented article deals with the influence of the heat treatment of C45 steel on the surface quality after turning. Turning is a machining technology used to prepare specific geometrical characteristics of surface and dimensional quality. In the present paper, the same turning conditions were used for the turning treatment of differently heat-treated steels. The soft annealed state, normalized state, hardened state, quenched and tempered at 530 &deg;C state and quenched and tempered at 660 &deg;C state have been analyzed. By using this approach, it has been possible to evaluate the effects of hardening and machining on the resulting parameters after turning (roughness, cylindricity and circularity). The highest hardness was observed in the steel after the hardening process (694 &plusmn; 9 HV 10). The hardening has negatively influenced the surface quality. The high hardness was related to martensite formation and caused a damage to the cutting edge of the cut insert used, leading to a significant change in geometrical accuracy. The cylindricity change achieved 0.15 &plusmn; 0.03 mm which was significantly higher compared to the theoretical value of the diameter of the machined steel bar. An inaccuracy was also observed in diameter dimension. These inaccuracies were caused by the wear of the cutting edge of the tool used in cutting parameters setting

2.4 GHz Electromagnetic Field Influences the Response of the Circadian Oscillator in the Colorectal Cancer Cell Line DLD1 to miR-34a-Mediated Regulation

Radiofrequency electromagnetic fields (RF-EMF) exert pleiotropic effects on biological processes including circadian rhythms. miR-34a is a small non-coding RNA whose expression is modulated by RF-EMF and has the capacity to regulate clock gene expression. However, interference between RF-EMF and miR-34a-mediated regulation of the circadian oscillator has not yet been elucidated. Therefore, the present study was designed to reveal if 24 h exposure to 2.4 GHz RF-EMF influences miR-34a-induced changes in clock gene expression, migration and proliferation in colorectal cancer cell line DLD1. The effect of up- or downregulation of miR-34a on DLD1 cells was evaluated using real-time PCR, the scratch assay test and the MTS test. Administration of miR-34a decreased the expression of per2, bmal1, sirtuin1 and survivin and inhibited proliferation and migration of DLD1 cells. When miR-34a-transfected DLD1 cells were exposed to 2.4 GHz RF-EMF, an increase in cry1 mRNA expression was observed. The inhibitory effect of miR-34a on per2 and survivin was weakened and abolished, respectively. The effect of miR-34a on proliferation and migration was eliminated by RF-EMF exposure. In conclusion, RF-EMF strongly influenced regulation mediated by the tumour suppressor miR-34a on the peripheral circadian oscillator in DLD1 cells

EN AW-2024 Wrought Aluminum Alloy Processed by Casting with Crystallization under Pressure

By using the wrought aluminum alloys can be created castings with higher mechanical properties than the castings made of standard foundry aluminum alloys, but it is necessary to handle the process of making sound castings without any defects such as hot tears and shrinkage porosity. In experiments, we have been studied of wrought aluminum alloy EN AW-2024 which has been processed by the casting with crystallization under pressure with forced flow. Castings were heat treated by standard T6 heat treatment

Expression of <i>esr1</i> and <i>esr2</i> receptors in the DLD1 cell line.

A cycle threshold (Ct) of 35 was considered the limit of PCR sensitivity in esr1 measurement. When Ct esr1 concentration was undetectable, Ct 35 was used for calculation of esr1 expression. Results are displayed as mean ± SEM (n = 6). Statistical differences were determined by an unpaired Student‘s t-test (***p esr1 –estrogen receptor type 1, esr2 –estrogen receptor type 2.</p

Proliferation of DLD1 cells measured 48 h after mir-34a transfection with or without parallel E2 administration.

Results are displayed as mean ± SEM (n = 8). Statistical differences were determined by one-way ANOVA followed by Dunnett’s multiple comparison test (*p < 0.05). NC–negative control, E2–17β estradiol.</p

Migration of DLD1 cells 24 h and 48 h after 17β-estradiol (E2) administration.

Upper panel shows wound closure in control (A) and 100 nM E2-treated DLD1 cells (B, magnification 40x). Lower panel shows the effect of E2 on migration of DLD1 cells after 24 h and 48 h of incubation. Results are displayed as mean ± SEM (n = 4). Statistical differences were determined by one-way ANOVA followed by Tukey‘s post hoc multiple comparison test (* p < 0.05). C–control without E2.</p

Sequences of the primers used in real-time polymerase chain reaction and reverse transcription.

Sequences of the primers used in real-time polymerase chain reaction and reverse transcription.</p