The specific activity concentration and the derived Annual Effective Dose(AED) in three types of vernonia cultivated and consumed within and outside Cameroon were measured by means of a well-calibrated high-purity germanium detector. Vernonia samples were collected directly from the production farms, oven-dried to a constant mass, crushed, sieved and sealed for at least a month before analysis. The specific activity of <sup>238</sup>U in the three types of vernonia ranged from 20 - 50 Bq kg<sup>-1</sup> with an average of 42 ± 15 Bq kg<sup>-1</sup>, <sup>232</sup>Th from 9 - 22 Bq kg<sup>-1</sup> with an average of 17 ± 7 Bq kg<sup>-1</sup> while <sup>40</sup>K ranged from 115 - 460 Bq kg<sup>-1</sup> with an average of 302 ± 36 Bq kg<sup>-1</sup>. The average AED for <sup>40</sup>K, <sup>238</sup>U and <sup>232</sup>Th were 0.15, 0.92 and 0.92μSv y<sup>-1</sup> respectively. <sup>238</sup>U and <sup>232</sup>Th show the same trends both for the regional distribution of the radioactivity content and the AED. The discrepancies in our data can be attributed to many factors such as geological formation, foliar deposition, type and age of the plant, etc. Although the results obtained represent only some fractions of the standard limit, but they are within some range obtained in other countries
A survey of radioactivity content and associated radiological risks was carried out in various soils used for agriculture and building materials in Cameroon by means of a well-calibrated high-purity germanium detector. Soil samples were collected directly from the agricultural farms and the brick's factories, air-dried at room temperature to a constant mass, crushed, sieved and sealed for at least one month before analysis. The specific activity of 238 U ranged from 5.36 ± 0.39 to 51.28 ± 9. ; The mean result obtained for the Representative levels index (I ), the radium equivalent (Ra eq ), the total absorbed dose rate (ADR), the external hazard index (H ex ), the internal hazard index (H in ) and the Ceasium intervention levels were 0.52, 72.75 Bq·kg , 0.29 Bq·kg −1 and 0.0028 Bq·cm 2 respectively. The discrepan-cies of our data can be attributed to several factors such as past nuclear disasters, geological formation, transport process, etc. Although our results are just some fractions of the international standard limit, but still within the same ranges when compared with those obtained elsewhere. This results also will serve as a baseline data for future inves-tigations.
A pattern inventory is developed for the enumeration of stable
stereo and position isomers of any series of
deoxycyclitols with the formula
(CH2)
p
(CHOH)
q
where p(CH2) and q(CHOH) groups form
a ring system of
size n = (p + q). The
counting method consists of two steps: firstly the application of
POLYA's counting
theorem gives the number of permutation isomers of the series; and
secondly, the sequential enumeration
of stable stereo and position isomers is carried out by applying
Balasubramanian's procedure to each
permutation isomer of the series. An illustration is shown in the
series of deoxycycloheptitols where p +
q = 7, 1 ≤ p ≤ 5 and 2 ≤ q ≤
6.
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