Exciton-polaron formation in GaGdN/AlGaN multiquantum wells was inferred from the lower energy of the photoluminescence peak observed for the GaGdN quantum wells (QWs) compared with GaN QWs. The rather low value of the excitonic transition energy is attributed to exciton-polarons bound to the Gd ions. Exciton-polarons are most likely to occur due to the lattice distortion around the substituted Gd ions in addition to the exchange interaction between Gd3+ magnetic ions and the strongly confined charge carrier spins in GaGdN QWs. The mechanism of exciton-polaron formation is discussed. The magnetic behavior is briefly presented.

The floristic composition and geographical elements of the study area were analyzed resulted in 328 species representing 206 genera in 55 families. This study confirmed the record of 14 species, mostly weeds, which can be considered as new additions to the flora of the study area. Therophytes were the dominant life form, while mono- and bi-regional Saharo-Sindian geoelements were the most represented. Ten species showed dominancy with their Q-values ranged between 0.802 and 0.2, where Zilla spinosa and Zygophyllum coccineum were of common occurrence. Application of cluster analysis and DCA ordination techniques produced 4 major floristic groups (A-D) comprising 7 subgroups. The correlation coefficients (r) between the different subgroups revealed high significant correlations (P=0.01) between floristic group (B) and subgroup (C2) and between subgroups (D1) and (D2). Significant correlations (P=0.05) occurred between subgroup (D1) and both of (A1) and (C2). Comparing the floristic similarities between this investigation and other relevant studies were presented and discussed. On the other hand the low similarity index between the study area and Sinai may be attributed to the geographical position of both deserts where Sinai desert is part of the Irano-Turanian region while the Eastern Desert is a part of the Saharo-Sindian region.

The present work investigated the radioactivity level of the rocks samples collected from different sites in Egypt. Twenty one rocks samples were analyzed by gamma-ray spectrometry using NaI(Tl) detector with specially designed shield. The concentration of three natural radionuclides namely 226Ra, 232Th and 40K has been determined and compared with chemical data obtained by XRF analysis. The results showed that these radionuclides were present in concentration ranges (3.4–99, 7.5–134 and 93–3382 Bq kg1), (54.9–211.6, 20.71–170.5 and 2068–2344 Bq kg1) and (13–106, 29.25–106.1 and 682–755 Bq kg1) for gneiss, granite and basalt rocks, respectively, while the values were (7.5, 12.5 and 263.9 Bq kg1) and (113, 148.5 and 1672 Bq kg1) for 226Ra, 232Th and 40K in sandstone and siltstone rocks, respectively. Also radium equivalent activity, total dose rates and external hazard index of the rocks samples under consideration were calculated. The results showed that granite rocks contain a high proportion of natural radioactive elements, while sandstone rocks have lesser radioactivity concentration compared with other types of rocks.

Water from bedrock frequently contains higher concentrations of natural radionuclides than water from other 22 sources. Groundwater from Assalamia-Alhomira and Juban areas (southeast of Sana'a) and hot spring water 23 from Dempt area (south Sana'a) in Yemen were analyzed for 226Ra, 232Th and 40 K activity concentrations. 24 The average activity concentrations for groundwater from Assalamia–Alhomira area were 4.04 Bql−1 and 25 1.81 Bql−1 for 226Ra and 232Th, respectively, while 40 K was not detectable, while that for groundwater sam- 26 ples from Juban area were 2.95 Bql−1, 0.72 Bql−1 and 34.9 Bql−1 for 226Ra, 232Th and 40 K, respectively. On 27 the other hand, the activity concentrations for hot spring water from Dempt area were 3.48 Bql−1, 1.01 28 Bql−1 and 16.05 Bql−1 for 226Ra, 232Th and 40K, respectively. Also annual effective dose equivalent of ingestion 29 of these waters was calculated. The results showed that the annual dose equivalent obtained in the present 30 study was much higher than the recommended value (0.1 mSv year−1) as reported by WHO. The results 31 were compared with those for drinking water.

The level of natural radioactivity in rocks and soil of 32 samples collected from locations at North Sana'a in Yemen was measured. Concentrations of radionuclides in rocks and soils samples were determined by gamma-ray spectrometer using high purity germanium (HPGe) detector with specially designed shield. The average radioactivity concentrations of 226Ra, 232Th, 40K were determined and expressed in Bq/kg. The results showed that these radionuclides were present in concentrations of 21.79 ± 3.1, 19.5 ± 2.6 and 399.3 ± 16 Bq/kg, respectively, for rocks. For soil, the corresponding values were 48.2 ± 4.4, 41.7 ± 4.5 and 939.1 ± 36 Bq/kg, respectively. Also, the radiological hazard of the natural radionuclide content, radium equivalent activity, total dose rates, external hazard index and gamma activity concentration index of the (rocks/soils) samples in the area under consideration were calculated. The dose rates at 1 m above the ground from terrestrial sources were 38.39 and 86.89 nGy/h for rocks and surface soil, respectively, which present no significant health hazards to humans.

The natural radioactivities of 40K, 226Ra, and 232Th and the fallout of 137Cs in rock and soil samples collected around Juban town in Yemen (south west of Asia) were measured. Concentrations of radionuclides in samples were determined by gamma-ray spectrometer using HPGe detector with specially designed shield. The average radioactivity concentrations of 226Ra, 232Th, and 40K were determined expressed in Bq/kg. The results show that these radionuclides were present in concentrations of (53.674, 12776.7, and 1742.8762 Bq/kg), (5574, 12176.6, and 2341778 Bq/kg), (212.878.7, 109 75.5, and 32.474.7 Bq/kg), and (32.173, 22.372.9 and 190.9715 Bq/kg) for granite, gneiss, siltstone, and sandstone rocks, respectively. For soil the corresponding values were 44.474.5, 58.275.1, and 822.7731 Bq/kg. Low deposits of 137Cs were noted in investigation area, where the activity concentrations ranged from 0.170.1 to 23.271.2 Bq/kg. Also the radiological hazard of the natural radionuclides content, radium equivalent activity, total dose rates, external hazard index, and gamma activity concentration index of the (rocks/soils) samples in the area under consideration were calculated. The data were discussed and compared with those given in the literature.

A series of coordination polymers of the general formula {[M(BDC)(azoles)(H2 O)m].xH2O}n (where M = Co(II), Ni(II), and Cu(II); BDC = 1,4-benzenedicarboxylate; azoles = 2-aminobenzothiazole, 2- aminothiazole, and 2-amino-4-methyl-thiazole; m = 0 or 1; and x = 1 or 2) were prepared and characterized. The complexes were characterized based on elemental analysis, infrared and electronic spectral studies, magnetic measurements, molar conductance, thermal analysis, X-ray diffraction, scanning electron microscopy, and biological activity. Thermogravimetry, derivative thermogravimetry, and differential thermal analysis were used to study the thermal decomposition of the complexes. The kinetic parameters were calculated making use of the Coats-Redfern and Horowitz-Metzger equations.

NMOR can be formed endogenously from nitrite and morpholine. Oxidative damage may represent an important step in the toxicity of NMOR. This study was designed to evaluate the biological activity of 3-aminothiazolo[3.2a]benzimadzole-2-carbonitrile in the protection of hepatic and renal tissues against oxidative stress that is induced by administration of nitrite and morpholine as food additives in drinking water for 15 weeks. Conclusions: Nitrite plus morpholine administration to rats results in oxidative damage in hepatic and renal tissues. This damage may return to the increased production of ROS and changes in the levels of antioxidants. This oxidative damage was ameliorated by DMSO and 3-aminothiazolo[3.2a]benzimadzole-2-carbonitrile co-treatment.

NMOR can be formed endogenously from nitrite and morpholine. Oxidative damage may represent an important step in the toxicity of NMOR. This study was designed to evaluate the biological activity of 3-aminothiazolo[3.2a]benzimadzole-2-carbonitrile in the protection of hepatic and renal tissues against oxidative stress that is induced by administration of nitrite and morpholine as food additives in drinking water for 15 weeks. Conclusions: Nitrite plus morpholine administration to rats results in oxidative damage in hepatic and renal tissues. This damage may return to the increased production of ROS and changes in the levels of antioxidants. This oxidative damage was ameliorated by DMSO and 3-aminothiazolo[3.2a]benzimadzole-2-carbonitrile co-treatment.

NMOR can be formed endogenously from nitrite and morpholine. Oxidative damage may represent an important step in the toxicity of NMOR. This study was designed to evaluate the biological activity of 3-aminothiazolo[3.2a]benzimadzole-2-carbonitrile in the protection of hepatic and renal tissues against oxidative stress that is induced by administration of nitrite and morpholine as food additives in drinking water for 15 weeks. Conclusions: Nitrite plus morpholine administration to rats results in oxidative damage in hepatic and renal tissues. This damage may return to the increased production of ROS and changes in the levels of antioxidants. This oxidative damage was ameliorated by DMSO and 3-aminothiazolo[3.2a]benzimadzole-2-carbonitrile co-treatment.