Minimizing the Micro-Edge Damage at Each Constituent Layer of the Clad Composite during AWJM

The development of layered/clad composites with a blend of desired characteristics has emerged as a valuable substitute for expensive materials. The inherent heterogeneity offers challenges whenever the cutting of cladded plates/sheets is to be done. The conventional means of cutting such as gas/plasma arc yield a poor cut quality and heat-affected zones. Abrasive waterjet machining (AWJM) is a valuable alternative to mitigate the aforesaid cutting issues. However, the intrinsic attribute of edge damage during AWJM poses a limitation on its use, especially for precision applications. Specifically, it is challenging to control the edge damage in terms of pit depth at both the constituent clad layers and addressing this challenge is the novelty of this work. The said cutting accuracy issues have been thoroughly investigated herein. Four key control parameters of AWJM have been selected for evaluating their impact during machining of stainless-clad steel using L18 Taguchi design. Experimental results have been thoroughly examined using statistical and microscopical evidence. The optimal parametric combination resulting in the minimum magnitude of pit depth at both the clad layers has been developed and experimentally validated. The magnitude of pits depth realized at stainless steel layer (SSL) and mild steel layer (MSL) significantly reduced to 5 µm and 4 µm respectively, at the optimal parametric combination.

Endoskopija u dijagnostici i lecenju inoperabilnog karcinoma jednjaka nakon radioterapije i kombinovane radiohemioterapije

Treatment of inoperable (locally advanced) esophagus cancer, even today, has been a subject of numerous clinical researches. Combination of several clinical modalities is needed, of radiotherapy and chemotherapy the most frequently. This combination applied as neoadjuvant or concomitant brought to improvement of treatment results of these patients. Local control is still a big problem, since majority of these patients die of local treatment "failure". Because of that, estimation of the local control is very important, ie. assessment of the tumor response the treatment. For those reasons, a study has been conducted on 52 patients with locally advanced esophagus tumor, who in the first group of 25 patients, were treated only by radiotherapy, and in the second group of 27 patients, by combined radio-chemotherapy. Pretherapy evaluation, evaluation of esophagus stenosis as well as the tumor regression to conducted treatment, were done in all patients by radiography and endoscopy and the findings were compared: there was no statistically significant difference between investigated methods (p>0.05). although bigger number of the tumor complete regressions was verified by radiography (6 in the first group and 5 in the second group of patients) in relation to endoscopic finding (3 in the first group and 2 in the second group of patients), which had no microscopical evidence of remaining disease. Partial tumor regression made greater differences between investigated methods (10:4 in the first group and 6:3 in the second group of patients).

Central neurotoxicity induced by subchronic exposure to 2,4-pentanedione vapour

1 Male and female Fischer 344 rats were exposed to 2,4- pentanedione (2,4-PD) vapour acutely (4 h) at 1265 or 1811 ppm, or for 6 h day-1 , 5 days a week for 14 weeks to 0, 101, 307 or 650 ppm. 2 Mortality occurred during or within a few hours of the acute exposures (10% at 1265 ppm; 70% at 1811 ppm). No animal had gross or microscopic brain lesions. 3 All female rats (20) and 10 of 30 male rats exposed to 650 ppm 2,4-PD vapour died by the 38th study day (29 exposures); there were no subsequent male deaths. Twenty-five of the 30 animals that died, and seven of the 15 males that survived, had light microscopical evidence of degenerative lesions, principally within the caudate/putamen nuclei, nuclei of the cerebellar medulla, and vestibular nuclei. Less frequently involved, in animals that died, were various regions of the cerebral cortex. The early histopathological lesions, seen from the 16th study day (12 exposures) to the 38th study day (28 exposures) were characterised by malacia. When present, lesions in male rats surviving the 14-weeks of 650 ppm 2, 4-PD expo sure were characterised by malacia and gliosis. No peripheral nerve lesions were seen by light or transmis sion electron microscopy. 4 Neither mortality nor neuropathology were seen in rats subchronically exposed to 101 or 307 ppm, 2,4-PD vapour.