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41.
T. Martinez M. Navarrete L. Cabrera F. Juárez A. Ramos K. Vazquez 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):569-572
Nine brands of tobacco cigarettes manufactured and distributed in the Mexican market were analyzed by γ-spectrometry to certify
their non-artificial radioactive contamination. Since natural occurring radioactive materials (NORM) 40K, 232Th, 235U, and 239U (and decay products from the latter three nuclides) are the main sources for human radiation exposure, the aim of this work
was to determine the activity of 40K and potassium concentration. Averages of 40K and potassium concentration were of 1.29±0.18 Bq·g−1, and 4.0±0.57%. The annual dose equivalents to the whole body from ingestion and inhalation of 26 Bq 40K were 0.23 μSv and 15.8 μSv, respectively. The corresponding 50 years committed dose equivalents was 0.23 μSv. The total
committed dose to the lungs due to inhalation of 40K in tobacco was 16 μSv. Potassium concentrations obtained in this work were in the same range of those obtained by INAA,
so showing that the used technique is acute, reproducible, and accessible to laboratories equipped with low background scintillation
detectors. 相似文献
42.
Do Young Kim Ji Sim Jung Young Rae Jang Kun Ho Yoo Jin Jang 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):400
We studied the growth of nanocrystalline silicon (nc-Si) thin film exhibiting a strong room temperature photoluminescence (PL) at 1.81–2.003 eV. The amorphous silicon was crystallized by Ni silicide mediated crystallization (Ni SMC) and then Secco-etched to exhibit the PL. The PL peak energy and intensity increase with increasing the metal density on the a-Si because of the reduction in the grain size down to 2 nm. The photoluminescence energy and peak intensity depend strongly on the Secco etch time because the grain size is reduced by etching the grain boundaries. 相似文献
43.
Ha Yong Lee Se Hun Jung Soo Yong Lee Young Ho You Kyung Hyun Ko 《Applied Surface Science》2005,252(5):1891-1898
Al-Al2O3 composite coatings with different Al2O3 particle shapes were prepared on Si and Al substrate by cold spray. The powder compositions of metal (Al) and ceramic (Al2O3) having different sizes and agglomerations were varied into ratios of 10:1 wt% and 1:1 wt%. Al2O3 particles were successfully incorporated into the soft metal matrix of Al. It was found that crater formation between the coatings and substrate, which is typical characteristic signature of cold spray could be affected by initial starting Al2O3 particles. In addition, when the large hard particles of fused Al2O3 were employed, the deep and big craters were generated at the interface between coatings and hard substrates. In the case of pure soft metal coating such as Al on hard substrate, it is very hard to get proper adhesion due to lack of crater formation. Therefore, the composite coating would have certain advantages. 相似文献
44.
Yang Ju Yo Hirosawa Masumi Saka Hiroyuki Abé 《International Journal of Infrared and Millimeter Waves》2003,24(3):391-397
We developed a compact equipment working at 94 GHz to replace the commonly used network analyzer for nondestructive testing of materials. The compact equipment was designed to measure the variations in the amplitude and phase of the reflected signal from the material relative to a reference signal. A good accuracy of the amplitude and phase measurement of the equipment was obtained in the confirmative experiments. The distribution of a drop of water in a wood plate is clearly visible in the millimeter wave images obtained by the amplitude and phase measurement. 相似文献
45.
Ru Ju Wang Feng Ying LiTing Zhang Deng Ji Fang WangHong Chen Chang Qing Jin 《Solid State Communications》2003,127(1):47-50
Using pulse echo overlap measurement, the elastic behavior of amorphous carbon has been studied at ambient and low temperatures. The smaller ratio B/G of the bulk modulus to shear modulus and smaller Poisson's ratio σ at room temperature indicate that there is an intrinsic stiffening of transverse acoustic phonons in the amorphous carbon. The acoustic velocity and attenuation for longitudinal modes have been measured between 2.1 and 300 K at three frequencies of 7, 21 and 35 MHz, respectively. Their frequency and temperature dependence are observed. The elastic constant C11 increases with decreasing temperature and show enhanced stiffening at low temperatures. In the 130-220 K region, the abnormal change and effect of longitudinal velocity and attenuation with temperature and frequency, and a phase transition associated with structure relaxations are discussed. 相似文献
46.
We will introduce new functional equations (3) and (4) which are strongly related to well-known formulae (1) and (2) of number
theory, and investigate the solutions of the equations. Moreover, we will also study some stability problems of those equations. 相似文献
47.
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50.
The concept of crystallization dynamics method evaluating the miscibility of binary blend system including crystalline component
was proposed. Three characteristic rates, nucleation, crystal growth rates (N*, G*) and growth rate of conformation (G
c*) were used to evaluate the miscibility of PVDF/at-PMMA and PVDF/iso-PMMA by the simultaneous DSC-FTIR. N*, G* and G
c* depended remarkably on both temperature and blend fraction (ϕPMMA) for PVDF/at-PMMA system, which indicated the miscible system. PVDF/iso-PMMA showed small ϕPMMA dependency of N*, G* and G
c*, was estimated the immiscible system. The ΔT/T
m0 values, corresponding to Gibbs energy required to attend the constant G* and G
c*, evaluated from G* and G
c* showed the good linear relationships with different slope. The experimental results suggested that the concentration fluctuation
existed in PVDF/iso-PMMA system. 相似文献