Background. The Weekly Mortality Cycle among CoViD-19 patients has been studied.Methods. Mortality data obtained from the 'Worldometer' website were analyzed with a comparison of absolute values, percentages, and p-value. Results. For patients suffering from CoViD-19, the most favorable or the safest days of the week were Sundays and Mondays. Conclusion. The weekly cycle with decreased mortality on Sundays and Mondays is a unique phenomenon observed among victims of CoViD-19. Presumably the decreased mortality on certain days of the week related to the optimized therapeutic protocols used on the "safest days".

Has anyone ever missed an event because he was confused in days and dates? Do we remember the date of any day without looking at a calendar? Is the current Gregorian Calendar efficient enough for use, and does it facilitate our life or make it more complicated? Have you ever thought about a much simpler way to calculate days and dates in a year? All these questions are answered in this paper, in which the author proposes original optimization algorithm that creates optimal perennial calendars. Results show that there is more than one way to create a perennial calendar, in which the number of days in each month does not change, neither the dates. Hence, all months have the same sequence of days and dates. In other meaning, Monday becomes the first day of every month, and Sunday becomes the last day. Consequently, the calendars become much easier to memorize and very simple to predict the days and dates in any year.

Copper smelting has been the source of soil contamination in trace metals in Penga Penga (Lubumbashi). Residents are exposed to trace metal ingestion and planting trees is challenging in such soil conditions. Nevertheless, planting trees in former household dumps or using various types of amendments allowed the provisioning of fruits in few residences. In the perspective of scaling up the process, a survey has been conducted with the aim of assessing the effectiveness of the planting processes on the trace metal content in fruits and leaves of Mangifera indica L. and Syzygium guineense (Willd) DC. Samples were collected in residential households from Penga Penga and Kalebuka (a non-polluted suburb). The bioconcentration factor (BCF) and the safe weekly consumption (SWC) were calculated for each species. Results showed higher values of total and soluble concentrations of Cu, Pb, and Zn in the rhizosphere of the two species at Penga Penga. Metal concentrations were higher in fruits and leaves from Penga Penga with 47% of samples above FAO and WHO thresholds (vs 18.5% in Kalebuka). The BCF values were below 1 demonstrating the effectiveness of the process to reduce metal translocation to leaves and fruits. Recommendations from the SWC limited by Pb for consumption to 9 kg for mango flesh and by Cd 6.6 kg for S. guineense fruits at Penga Penga (Vs 78 and 68 kg at Kalebuka). Finally, results from this study provide interesting lessons from the scaling up and the technical itinerary of planting tree un Penga Penga.

Mercury (Hg) fish and seafood contamination is a global concern and needs worldwide sea investigations in order to protect consumers. The aim of this study was to investigate the Hg concentration by means of a rapid and simple analytical technique with direct Mercury Analyzer (DMA-80) in pelagic fish species, Tetrapturus belone (spearfish), Thunnus thynnus (tuna) and Xiphias gladius (swordfish) caught in the Mediterranean Sea. Hg contents were evaluated also in Salmo salar (salmon) as pelagic fish not belonging to the Mediterranean area. The results obtained were variable ranging between 0,015-2,562 mg kg-1 for T. thynnus specie, 0,477-3,182 mg kg-1 for X. gladius, 0,434-1,730 mg kg-1 for T. belone and 0,004-0,019 mg kg-1 for S. salar, respectively. The total Hg tolerable weekly intake (TWI) and % tolerable weekly intake (TWI%) values according to the European Food Safety Authority (EFSA) were calculated. The results highlighted that the pelagic species caught in the Mediterranean Sea should be constantly monitored due to their high Hg contents as well as their TWI and TWI% with respect to S. salar samples.

The time series of daily new cases of Covid-19 infection in different zones of Italy, several European countries and New York City were analyzed in order to characterize the large fluctuations contained in them. The comparison shows that the time series share a similar evolution, although with delays of one or two weeks, with Italy that precedes the other countries. Correlation analysis indicates a strict resemblance between the time series of the first differences, which emphasize accelerations and slowdowns of the epidemic (e.g., correlation coefficient r=0.70 for Italian vs. worldwide data). According to Fourier analysis the signals have a dominant oscillatory component at a period of seven days, with minima located near the weekends. Some of the possible causes of this time modulation are discussed. In particular, it is hypothesized a delayed or missed recognition of a significant fraction of the new cases during the weekend, with possible consequences for the evolution of the epidemic.