درخت حوزه‌های تخصصی

In a survey carried out in the Sadrabad area of ​​Zarandieh in June 2020, in addition to the whole village of Sadrabad, its satellite areas were also examined and identified, which led to remarkable results in the archaeological studies of the Iranian plateau, which in addition to other archaeological survey, metal slags were also studied and analyzed there. Slag is the residue of minerals from the smelting, which occurs naturally as a molten silicate or as a mixture of several silicate minerals with compounds of oxides, sulfides, and metals. To detect metal minerals in slag, it is necessary to prepare a polished section from the samples in order to identify its  type . The silicate minerals in the slag are studied with  passing light using a thin section. Gazanak Zarandieh Tepe is located 85 km from Tehran and 75 km from Saveh in Sadrabad Vilage in Zarandieh city of Markazi province. The oldest settlement phase identified in this area is Neolithic (or Pre-pottery Neolithic) and the newest period identified is related to the Safavid era. In this survey, we obtained evidence of smelting and processing of copper, which included pure native copper and slag from smelting of this metal, which by integrating them for laboratory studies, especially the petrographic elemental analysis, which resulted in amazing results. The purpose of petrographic testing on study samples is to identify the components of the slag, the type of material extracted and, if possible, the host rock mineral. Since the study area lacks Chalcolithic age, and the abundance of plum ware, which appeared in the context of Cheshmeh Ali pottery and the transition period according to the speculation of the 2021 season, led us to the question that melting and extraction copper metal in the center of the Iranian plateau has an older history than the dates presented in this article.

One of the most important factors that investors pay attention to in stock markets is stock price fluctuations, which is the basis for evaluating the performance of company managers. The performance of the company's stock includes the yield from the resources under the company's control and is considered a suitable criterion for reaching the set goals. In the meantime, one of the things that influenced widely on the world financial markets is the outbreak of the 2019 Covid-19 epidemic. The Covid-19 pandemic is known as a black swan event since it was a rare, unexpected, unknown phenomenon with a high and universal impact. Therefore, the current research purpose is to investigate the fluctuations in the stock prices of petrochemical industry companies affected by the Covid-19 pandemic. For this purpose, 19 petrochemical companies of Tehran stock exchange were studied between 2017 to 2022. The data gathered daily and included 19 petrochemical companies in 220 working days for 5 years. The results showed that the shock caused by the growth of the corona virus initially caused a decrease in price volatility in petrochemical companies, but after two periods, the reaction of price volatility to the shock was positive. Finally, the shock effect disappeared after seven cycles.