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Rzezba strukturalna Pogorza Kaczawskiego i polnocno-wschodniej czesci Pogorza Izerskiego

100%

Adam A.

2004

nr 07

175-190

Evaluation of specific process parameters and ultrasonically activated injection affecting the quality of filling in thin walled plastic parts

51%

Adam A. , Stan D. , Tulcan A.

Journal of Theoretical and Applied Mechanics

2015

tom Vol. 53 nr 4

799—809

The paper presents a set of experiments focused on the study of rheological behavior of a polymer flowing through a narrow section at the forming by injection of thin-walled plastic parts. The paper addresses the use of ultrasonically activated injection for fabrication of polymeric parts with thin wall features. In the experiment, a part with six different geometric features has been created. The design-of-experiments approach is applied to correlate the quality of the parts with the processing parameters. Four processing parameters are investigated using a screening factorial experimentation plan to determine their possible effect on the filling quality of the moulded parts. The experiments have been conducted on a hot runner mould with two nests in which the final (nest) nozzle has been modified to host, as the central element, the ultrasonic horn of a sonic system. It has been found that the ultrasonic activation applied on the active part of the mould does not play an important role as a stand-alone factor but could amplify or strengthen the effect of classical setting parameters (and influence factors) of the process: the melt temperature and injection pressure. Because it is easier to stimulate and to control rheological properties of the melt by setting the intensity of ultrasonic energy and, more important, the effect is forthwith, the paper recommends the runner systems with ultrasonic activation as an alternative for the hot runner with heating elements.

Selective neuronal death following exposure to methylenedioxypyrovalerone is accompanied by an inhibition of NMDA receptor NR2B subunit expression

38%

Gerecsei L. I. , Balazsa T. , Echevarria D. , Adam A. , Zachar G. , Csillag A.

nr 1

In a previous study, methylenedioxypyrovalerone (MDPV), a designer drug of the cathinone family, caused selective enhancement of Caspase3 immunoreactive (Casp3+) apoptotic cells in the nucleus accumbens (NAc) of 7-day-old mice. To further elaborate on the mechanism underlying MDPV-elicited apoptosis, here, we investigated the appearance of Casp3+ cells in developing neural tube explants of E12.5 mice, following MDPV treatment in vitro. Apoptotic cells appeared in large number in the pallium as radial progenitor cells and multipolar neurons, and in the subpallium including the future NAc, both in control and MDPV treated specimens. MDPV did not cause gross morphological changes in the neural tube or in the abundance of Casp3+ cells, based on a visual impression, though quantification was not attempted. We also studied the changes in NMDA receptor (NMDAR) protein subunits NR1 and NR2B in the NAc of 7-day-old MDPV treated and control mice, using western blotting of tissue obtained by selective dissection. In MDPV treated animals, expression of NR2B was lower than in the control animals, whereas expression of NR1 did not differ significantly from controls. The findings indicate that, during early postembryonic development, downregulation of the NR2B receptor subunit (at this time predominant in the NMDAR) is accompanied by a decreased viability of neurons. Decreased viability is expressed, in this case, as enhanced susceptibility to stimulation by MDPV – essentially a robust dopaminergic agent, potently affecting the neurons of the NAc. The findings are likely relevant to dopaminergic/NMDAR interactions and a potential pro-survival role of the NR2B subunit in critical phases of neural development.