A total of 779 samples of edible nuts (melon seeds, watermelon seeds, pumpkin seeds, and cantaloupe seeds) from southern cities of Punjab, Pakistan were collected from the summer and the winter seasons. The natural occurrence of aflatoxins (AFs) and vitamin E (tocopherols) levels were investigated using HPLC. The results have shown that 180 (43.4%) samples from the winter season and 122 (33.4%) samples from the summer season were found positive with AFs. The elevated average levels of total AFs (20.9±3.10 µg/kg) were observed in watermelon seeds without shell and the lowest average amount (15.9±3.60 µg/kg) were documented in melon seeds without shell samples from the winter season. The elevated average amount of total AFs 17.3±1.50 µg/kg were found in pumpkin seeds available as without shell. The results have documented a significant difference in total AFs levels in edible seeds available as shells versus without shells (α = 0.05 & 0.01). The highest dietary intake of 6.30 µg/kg/day was found in female individuals from pumpkin seeds (without shell) in the winter season and the value of 3.00 µg/kg/day were found in pumpkin seed without shell in summer season in female individuals. The highest amount of total tocopherol levels of 22.2 ± 7.70 ng/100g in pumpkin seeds samples from winter season and 14.5 ± 5.50 mg/100g were found in melon seeds samples from summer season. The variation of total tocopherol levels in edible seeds among the winter and summer seasons showed significant difference (p ≤ 0.0054), except watermelon seeds samples which shown non-significant difference (p ≥ 0.183).

A total of 744 samples of vegetable seeds and oil (soybean, sunflower, canola, olive, corn, and mustard) were collected for the presence of aflatoxin B1 (AFB1) and total aflatoxins (AFs). The results have shown that 92 (56.7%) samples of branded and 108 (57%) samples of non-branded edible seeds were observed to be contaminated with AFs. The maximum mean of AFB1 and total AFs in non-branded soybean seeds was 21.01 ± 4.70 and 36.37 ± 6.10 µg/kg, respectively. Furthermore, all samples of edible seeds have concentrations of AFB1 greater than the proposed limit of European Union (EU, 2 µg/kg) and 12 (7.40%) samples of branded seeds and 14 (7.40%) samples of non-branded seeds were found in the range ≥ 50 µg/kg. About 78 (43.3%) samples of branded edible oil and 103 (48.3%) sample of non-branded edible oil were observed to be positive with AFs, and the elevated average of AFB1 (14.29 ± 2.51 µg/kg) and total AFs (25.61 ± 7.50) µg/kg were found in non-branded soybean oil samples. Furthermore, 16 (8.88%) and 6 (3.33%) samples of branded vegetable oil have levels of total AFs in a range (21 - 50 µg/kg) and ≥ 50 µg/kg, respectively. The findings have indicated significant difference of AFs levels between branded and non-branded vegetable oil samples (t = 22.274 and p = 0.000) at α = 0.05 and significant difference of AFs levels in vegetable seeds and oil samples ( t = -17.75, p = 0.000) at α =0.05. The highest dietary intake was found in non-branded sunflower oil sample (0.90 µg/kg/day) in female individuals (16-22 age group), followed by the dietary intake of 0.69 µg/kg/day body weight in male individuals (16-22 age group).

Channel estimation is an important module to enhance the performance of orthogonal frequency division multiplexing (OFDM) systems. However, the presence of a large amount of noise in multipath fading time-varying channels significantly affects the channel estimation accuracy and thus the recovery quality of the received signals. Therefore, this paper proposes a double-threshold (DT) channel estimation method based on adaptive frame statistics (AFS). The method first adaptively determines the number of statistical frames based on the temporal correlation of the received signals, and preliminarily detects the channel structure by analyzing the distribution characteristics of multipath sampling points and noise sampling points during adjacent frames. Subsequently, a multi-frame averaging technique is used to expand the distinction between multipath and noise sampling points. Finally, the DT is designed to better recover the channel based on the preliminary detection results. Simulation results show that the proposed adaptive frame statistics-double-threshold (AFS-DT) channel estimation method is effective and has better performance compared with many existing channel estimation methods.