Investigation of Vegetable Oils and Their Derivatives for the Synthesis of Extreme Pressure Additives.

The harmful effects of wear can be reduced through proper lubrication of the frictional parts. When exposed to excessive loads, the lubricant film is displaced from the surfaces, and even the adhesive lubricant layer may rupture. Additives known as Extreme Pressure (EP) are frequently incorporated into lubricants to minimise wear and avert seizures under high temperature and pressure. Mechanistically, these additives generate a film on the surface through chemisorption. These additives are extensively applied in various lubricants, with the largest quantities being employed in metalworking fluids and lubricating greases. Sulfurized vegetable oils and their derivates can be used as EP additives for lubricants. To conduct the investigations, sulfurized additives were synthesized using different vegetable-based oils and fatty acid esters, and alpha-olefins. In this study, the Four-ball test results were compared to gain a more accurate comprehension of how various raw-material-based additives influence wear and friction. The goal was to select raw materials that could be used with favorable results for the production of EP additives. The objective was to achieve a minimum Four-ball weld load parameter of 2000 N. The experiments revealed that the functional impacts of the synthesized samples are dependent on the type of raw materials employed. Based on the experimental data and the stated criteria, the examined raw materials were found to be suitable for the synthesis of EP additives.

[Myocardial infarction of rare etiology in a young adult]. / Ritka etiológiájú fiatalkori szívinfarktus.

Chest pain is not uncommon among young patients below the age of 35 years, however, it is rarely caused by acute coronary syndrome. The rarity of coronary artery occlusion in this population can easily lead to diagnostic mistakes. The authors present the case history of a 19-year-old young female, who was admitted to the emergency department of a local hospital due to the sudden onset of chest pain and malaise. ST-segment elevation was seen on the electrocardiogram raising the possibility of aortic dissection, therefore, emergency thoracic computed tomographic scan was performed. This proved to be negative and the patient was transferred to the coronary care unit. Urgent coronarography was carried out, which revealed the total occlusion of the left main coronary artery. The occluded artery was successfully opened with percutaneous coronary intervention, but despite revascularisation the patient died on the second postoperative day due to asystole. Autopsy revealed thrombotic embolization of the left main artery with consequent extensive haemorrhagic necrosis, involving almost the whole left ventricle. The source of embolization was not found. The authors note that left coronary artery occlusion in young patients can be a diagnostic challenge, because symptoms can be mistaken with aortic dissection or pulmonary embolism.