Annual effective dose due to natural radionuclides in building blocks in eight cities of Southwestern Nigeria

The specific absorbed dose rates due to (226)Ra, (232)Th and (40)K in building blocks have been determined for a model dwelling dimension of 3.6 x 3.6 x 3.0 m(3), wall thickness 10 cm and density of 1.73 x 10(3) kg m(-3) in eight cities across Southwestern Nigeria. The Mustonen method of calculating gamma-ray annual exposure rate from the radioactivity concentrations (Bq kg(-1)) of (226)Ra, (232)Th and (40)K in the blocks have been adopted with modifications to suit the Nigerian situation. The specific absorbed dose rates obtained were as follows: 11.36, 14.94 and 0.92 microGy y(-1) per Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. These dose rates were used to calculate the annual effective dose in the model dwelling. The annual effective dose obtained varied between 209.20 (Osogbo) and 400.36 microSv y(-1) (Abeokuta). The values are in the range of values obtained for the German Democratic Republic (309 microSv y(-1)) and Jordan (470 microSv y(-1)).     

Numerical simulations of subsurface probing in diffusely scattering media using spatially offset Raman spectroscopy

We present the first elementary model predicting how Raman intensities vary for a range of experimental variables for spatially offset Raman spectroscopy (SORS), a recently proposed technique for the effective retrieval of Raman spectra of subsurface layers in diffusely scattering media. The model was able to reproduce the key observations made from the first SORS experiments, namely the dependence of Raman signal intensities on the spatial offset between the illumination and collection points and the relative contributions to the overall spectrum from the top layer and sub-layer. The application of the SORS concept to a three-layer system is also discussed. The model also clearly indicates that an annular geometry, rather than a point-collection geometry, which was used in the earlier experiments, would yield much improved data.     

Studies on energetic compounds part 8 : thermolysis of salts of HNO(3) and HClO(4)

The thermolysis of various substituted ammonium salts of nitric and perchloric acids has been reviewed in the present communication. The mechanistic aspects of thermal decomposition of these salts have been discussed critically. It has been observed that the proton transfer process do play a major role during thermolysis of these salts. The plausible decomposition pathways have also been described.     

Interferometric data analysis based on Markov nonlinear filtering methodology

For data processing in conventional phase shifting interferometry, Fourier transform, and least-squares-fitting techniques, a whole interferometric data series is required. We propose a new interferometric data processing methodology based on a recurrent nonlinear procedure. The signal value is predicted from the previous step to the next step, and the prediction error is used for nonlinear correction of an a priori estimate of the parameters phase, visibility, or frequency of interference fringes. Such a recurrent procedure is correct on the condition that the noise component be a Markov stochastic process realization. The accuracy and stability of the recurrent Markov nonlinear filtering algorithm were verified by computer simulations. It was discovered that the main advantages of the proposed methodology are dynamic data processing, phase error minimization, and high noise immunity against the influence of non-Gaussian noise correlated with the signal and the automatic solution of the phase unwrapping problem.     

Occupational radiation protection dosimetry in Nigeria

The general features of occupational radiation protection dosimetry in Nigeria within the period 1990-1999 have been summarised. About 640 personnel, representing about 25% of the estimated number of radiation workers in Nigeria, were monitored by the TL dosimetry technique during the period, with the majority being the personnel of the teaching hospitals across the country. Most private establishments, especially the X ray diagnostic centres, operate without dosimetry coverage or supervision by a regulatory authority. The weighted mean of the annual effective dose ranged between 0 and 28.97 mSv with the upper limit of collective effective dose being 18.47 man.Sv per year. The individual risk estimate due to this is about 1.5 x 10(-3) per year and this was among the medical personnel. The value could be more if all radiation workers in the country were monitored.     

Population dose due to building materials in Ibadan, Nigeria

The natural radionuclide contents of some concrete building blocks randomly sampled in the city of Ibadan have been determined using NaI(Tl) gamma ray spectrometry. The radionuclides 226Ra, 232Th and 40K were determined with city mean specific activities 47 +/- 21 Bq.kg-1, 52 +/- 21 Bq.kg-1, and 352 +/- 222 Bq.kg-1, respectively. These activities amount to a radium equivalent of about 150 Bq.kg-1, which is lower than the recommended maximum value of 370 Bq.kg-1. The mean value of the external hazard index was found to be 0.41 which implies that the building blocks used in the city of Ibadan are within the acceptable level of radioactivity. The mean indoor gamma dose equivalent to individuals due to the walls was calculated to be 412 microSv.y-1 and the collective dose equivalent 563 man.Sy.y-1.     

季铵盐聚合物/封端聚氨酯共混物防污涂料的制备与性能

用溶液聚合法合成了甲基丙烯酸缩水甘油醚-甲基丙烯酸丁酯共聚物,然后通过共聚物中环氧基与盐酸和三甲胺的反应制备了相应的季铵盐聚合物(QASP),并制备了QASP/封端聚氨酯(BPU)共混物防污涂料。测试结果表明,随着共混物涂料中BPU用量的增加,涂层的拉伸强度下降,断裂伸长率增加,剪切强度增加;氧化亚铜能增强涂层的疏水性和降低涂层的表面能;防污涂料中铜离子渗出率保持在比较高的水平,防污性能比较明显。     

对我省做好废纸使用工作的几点意见

对我省做好废纸使用工作的几点意见刘明光山东造纸印刷企业联合（集团）总公司２５００１３关键词废纸使用，废纸分类标准，强化管理工作，改进当前生产近年来我省造纸工业使用废纸的数最迅猛增加，纸板原料７０％以上是废纸，使用废纸脱墨生产新闻纸、书写印刷用纸、生活...