Self-ordering process of phenanthrene polyesters observed by the simultaneous DSC-XRD method

Phase transition behavior of polyesters derived from 2,7-phenanthrene dicarbonic acid diethylester and alkanediols with even methylene carbon number was investigated by the simultaneous DSC-XRD method. The smectic A phase was observed on cooling from the molten state. The transition entropy from the isotropic state to the smectic A phase was about 9.0 J mol^-1 K^-1, which depended on the methylene carbon number. The linear expansion coefficients, based on the (001) spacing of the crystalline phase at room temperature, were 1.3·10^-4 K^-1 (crystalline phase), 5.7·10^-4 K^-1 (crystallization region), 1.7·10^-3 K^-1 (smectic A phase) during cooling, and 1.5·10^-4 K^-1 (crystalline phase), and 1.0·10^-3K^-1(melting region) on heating. This revised version was published online in July 2006 with corrections to the Cover Date.     

Radioactive nuclides as tracers of environmental processes

Summary Relatively short-lived radioactive nuclides of cosmogenic origin, such as⁷Be (T_1/2=53.3 d),³²P (14.3 d),³³P (25.3 d),³⁵S (87.4 d) as well as²²Na (2.6 y) have come to be recognized as potential tools to trace environmental processes, such as precipitation, washout (precipitation scavenging), resuspension, atmospheric particle deposition and deposition patterns of airborne contaminants, aerosol deposition and aerosol trapping by above ground vegetation (air-to-vegetation transfer). Of the above radionuclides,⁷Be as well as²¹⁰Pb of terrestrial origin and¹³⁷Cs, a fission product radionuclide, are commonly used for determining the atmospheric particle deposition parameters. It was found that the deposition velocity of⁷Be-associated aerosol particles varied from 0.3 to 0.8 cm^. s^-1(average 0.5 cm^. s^-1), the washout ratio for⁷Be varied from 103 to 375 (average 144), the resuspension factor for the⁷Be-associated particles varied from 1.6^. 10^-4to 4.2^. 10^-4m^-1(average 2.3^. 10^-4m^-1) and the air-to-vegetation transfer rate for⁷Be varied from 5258 to 16180 m^3.kg^-1(average 9856 m^3.kg^-1) for grass, gramineae or poaceae the species. For the¹³⁷Cs-associated aerosol particles the deposition velocity varied from 1.3 to 6.3 cm^. s^-1(average 3.4 cm^. s^-1), the washout ratio for¹³⁷Cs varied from 284 to 3810 (average 1295), the resuspension factor for the¹³⁷Cs-associated aerosol particles varied from 0.1^. 10^-4to 1.2^. 10^-4m^-1(average 0.6^. 10^-4m^-1) and the air-to-vegetation transfer rate for¹³⁷Cs varied from 39638 to 345279 m^3.kg^-1(average 181197 m^3.kg^-1) for grass, gramineae or poaceaethe species.     

Distribution of natural radionuclides and hot points in coasts of Hormozgan, Persian Gulf, Iran

Summary A reconnaissance study has been made on the distribution of ²³⁸U, ²³² Th, ⁴⁰K, ¹³⁷Cs and geochemical features in soil and sediment samples at various locations in the coast of Persian Gulf. Activity concentration levels due to radionuclides were measured in 50 samples of soils and sediments collected from the coast of Hormozgan. From the measured spectra, activity concentrations were determined for ⁴⁰K (range from 140 to 1172 Bq ^. kg^-1), ¹³⁷Cs (from 0 to 15 Bq ^. kg^-1), ²³⁸ U (from 29 to 385 Bq ^. kg^-1) and ²³²¹ Th (from 9 to 156 Bq ^. kg^-1) with the lowest limit of detection (LLD) of 68, 3.2, 4.3 and 4.3 Bq ^. kg^-1, respectively. The dose rate from ambient air at the soil ranges was between 23 to 177 nGy ^. h^-1 with an average of 60±7.86 nGy ^. h^-1.     

Global fallout levels of <Superscript>99</Superscript>Tc and activity ratio of <Superscript>99</Superscript>Tc/<Superscript>137</Superscript>Cs in the Pacific Ocean

Summary Global fallout levels of ⁹⁹Tc and ¹³⁷Cs of surface seawater in the Pacific Ocean were measured. The ⁹⁹Tc concentrations ranged from 0.62 to 3.33 mBq^. m^-3and 5 of 6 samples showed less than 1 mBq^. m^-3except one sample taken in the Great Barrier Reef, Australia. The ¹³⁷Cs concentrations ranged from 2.13 to 3.14 Bq^. m^-3, showing a gradual decrease in the North Pacific toward the equator and a constant level in the South Pacific. The ⁹⁹Tc/¹³⁷Cs activity ratios ranged from 2.5^. 10^-4to 2.9^. 10^-4, which is very close to that calculated theoretically from the fission yield.     

Mono- and dinuclear Zn(II) complexes of Schiff-base ligands: syntheses,characterization and studies of photoluminescence

Six Schiff-bases HL¹-HL⁴, L⁵ and L⁶ [HL¹ = 2,6-bis[1-(2-aminoethyl)pyrolidine-iminomethyl]-4-methyl-phenol, HL² = 2,6-bis[1-(2-aminoethyl)piperidine-iminomethyl]-4-methyl-phenol, HL³ = N-{1-(2-aminoethyl)pyrolidine}salicylideneimine, HL⁴ = N-{1-(2-aminoethyl)piperidine}salicylideneimine, L⁵ = 2-benzoyl pyridine-N-{1-(2-aminoethyl)pyrolidine}, L⁶ = 2-benzoylpyridine-N-{1-(2-aminoethyl)piperidine}] have been synthesized and characterized. Zn(II) complexes of those ligands have been prepared by conventional sequential route as well as by template synthesis. The same complexes are obtained from the two routes as evident from routine physicochemical characterizations. All the Schiff-bases exhibit photoluminescence originating from intraligand (π–π*) transitions. Metal mediated fluorescence enhancement is observed on complexation of HL¹-HL⁴ with Zn(II), whereas metal mediated fluorescence quenching occurs in Zn(II) complexes of L⁵ and L⁶.     

Inorganic ion-exchangers in radioactive waste management</p> </p>

Summary The uptake of indigenously synthesized amorphous stannic and zirconium phosphate was assessed for, one of the important fission fragment, cesium from aqueous solutions using a radiotracer technique. A virtual increase in sorptive concentration (from 1.0 ^. 10^-8 to 1.0 ^. 10^-2 mol ^. dm^-3) and pH (from 2.4 to 10.2) and temperature (from 303 to 333 K) enhanced the uptake of cesium on stannic phosphate. However, the extremely high degree of uptake of cesium on zirconium phosphate was almost unaffected with the dilution beyond 10^-5 mol ^. dm^-3 and pH (i.e., from 2.4 to 10.2) and temperature (from 303 to 323 K). Irreversible uptake occurring for these solids follow the Freundlich adsorption isotherm and the presence of several complexing agents viz., sulphate, phosphate, glycine and EDTA did not affect appreciably the uptake of cesium on zirconium phosphate but it did affect for stannic phosphate system. Both these solids showed good radiation stability towards a 11.1 GBq Ra-Be neutron source having neutron flux ca. 3.2 ^. 10⁶ n ^. cm^{-2 .} s^-1 and associated with a nominalg-dose of ca. 1.72 Gy/h, at least for the uptake of cesium.</p> </p>     

Determination of the radon diffusion coefficient and radon exhalation rate in Moroccan quaternary samples using the SSNTD technique

Measurements have been made of radon (²²²Rn), release from diverse quaternary samples collected from different sediment deposits in the Errachidia and Beni-Mellal areas (Morocco). The radon diffusion coefficient as one of some important parameters of radon transport in the soil has been measured using solid state nuclear track detectors (SSNTD). Radon -activity, uranium content and radon exhalation rate have been determined in the studied samples. Uranium concentrations were found to vary from 0.14 to 9.52 ppm whereas the radon exhalation rate varied from 0.003 to 0.145 Bq^.m^-2.h^-1. A positive correlation has been found between radon exhalation rate and uranium content in the studied samples. The average radon diffusion coefficients were found to vary from (1.26±0.09)^.10^-6 m^2.s^-1 to (4.3±0.36)^.10^-6 m^2.s^-1. Furthermore, the correlation between ²²²Rn diffusion coefficient and porosity are also discussed.     

Fe3+和Fe2+对原代培养的成骨细胞增殖、分化和矿化功能的影响

采用噻唑蓝(MTT)法、碱性磷酸酶(ALP)比活性测定、油红O染色和茜素红染色及定量分析,研究了不同浓度的Fe3+和Fe2+对原代培养的成骨细胞增殖、分化及矿化功能的影响.结果表明:浓度为1×10-9～1×10-4 mol·L-1的Fe3+和Fe2+促进成骨细胞增殖,但是在较高浓度1×10-3 mol·L-1时,它们则抑制成骨细胞增殖.与成骨细胞作用48 h,浓度为1×10-8～1×10-4 mol·L-1的Fe3+和Fe2+抑制其分化,但在较低的浓度1×10-9 mol·L-1时则对其分化没有影响:进一步延长作用时间为72 h,Fe3+对成骨细胞分化没有影响,除1×10-6mol·L-1浓度的Fe2+促进成骨细胞分化外,其他浓度的Fe2+则抑制其分化;测试浓度下的Fe3+对成骨细胞向脂肪细胞的横向分化表现为抑制或没有影响,而Fe2+的影响则依赖于浓度和作用时间.在1×10-8～1×10-5mol·L-1浓度范围内,Fe3+和Fe2+对矿化结节的影响表现出相反的效应.在较高浓度(1×10-4mol·L-1)下,它们促进矿化节结的形成,而在较低浓度(1×10-9mol·L-1)下,Fe3+抑制矿化节结的形成,Fe2+则没有影响.结果提示:浓度.作用时间和铁离子的价态都是影响Fe3+和Fe2+生物效应(从毒性到活性,从损伤到保护,从上调到下调)转变的关键因素.     

Activity concentrations of selected artificial and natural radionuclides in water and sediment samples from the North Western Black Sea, 1999

Radioactive concentrations of several artificial and natural radionuclides were determined in water and sediment samples collected from various locations in the NW Black Sea in December 1999. For water samples, ⁹⁰Sr and ¹³⁷Cs activity concentrations were of approximately 11 mBq/l and 26.3-41.2 mBq/l, respectively. The concentration of tritium ranged from 7 to 24 T.U. In sediment samples, maximum concentrations of ¹³⁷Cs, ^239+240Pu and ²⁴¹Am were found of 128±6 Bq·kg^-1, 1.8±0.1 Bq·kg^-1 and 0.05±0.04 Bq·kg^-1, respectively. For U and Th radionuclides, the concentrations ranged from 20-80 Bq·kg^-1 and 30-50 Bq·kg^-1, respectively. The results were consistent with those reported in earlier research for the Black Sea. This revised version was published online in July 2006 with corrections to the Cover Date.     

Simultaneous analysis of 137Cs, 90Sr, 238Pu and 239+240Pu in Brazilian seawater

Methodologies for simultaneous analysis of ¹³⁷Cs, ⁹⁰Sr, ²³⁸Pu and ^239+240Pu were developed and applied to seawater samples. ¹³⁷Cs levels in Brazilian coastal seawater ranged from 0.12 to 4.7 Bq·m^-3, for ⁹⁰Sr from 2.0 to 8.6 Bq·m^-3, for ^239+240Pu from 0.8 to 4.5 mBq·m^-3 and for ²³⁸Pu it was of 1.9 mBq·m^-3. The artificial radioactivity levels in Brazilian seawater are typical values due to fallout deposition.     

Cu2+和Cu+对原代培养的小鼠成骨细胞增殖、分化和钙化的影响

利用噻唑蓝(MTT)法、碱性磷酸酶(ALP)比活性测定、油红O染色和矿化结节染色及定量分析,研究了Cu²⁺和Cu⁺对原代培养的成骨细胞增殖、分化及钙化的影响。结果显示：Cu²⁺(1×10^-9~1×10^-6 mol·L^-1)促进成骨细胞增殖,随时间延长,促进作用变弱。Cu⁺(1×10^-7~1×10^-5 mol·L^-1)抑制成骨细胞增殖,随时间延长,浓度为1×10^-6 mol·L^-1的Cu⁺为促进作用,其余浓度则没有影响。对于成骨细胞分化,Cu²⁺和Cu⁺表现出相似的影响,浓度为1×10^-9和1×10^-6 mol·L^-1时均促进成骨细胞分化,而当浓度为1×10^-7和1×10^-5 mol·L^-1时,则抑制成骨细胞分化,随作用时间延长,大多数浓度均表现为促进作用。测试浓度下的Cu²⁺和Cu⁺均对成骨细胞向脂肪细胞的横向分化表现为促进效应。对矿化功能的影响,1×10^-5 mol·L^-1的Cu²⁺和Cu⁺表现出显著的抑制效应,但随浓度降低,抑制效应变弱。1×10^-7 mol·L^-1的Cu²⁺ 促进成骨细胞矿化结节的形成。结果提示：作用浓度、作用时间及铜离子的价态都是影响Cu²⁺和Cu⁺生物效应转变(从毒性到活性,从损伤到保护,从下调到上调)的关键因素。     

Tritium concentration in fresh,brackish and sea-water samples in Rokkasho-Village,Japan, bordered by nuclear fuel cycle facilities

Summary In order to identify the concentration of tritium (³H) in areas of fresh, brackish and sea water, bordered by nuclear fuel facilities at Rokkasho-Village, Aomori, Japan, water samples were collected from 2001 to 2004 at six points in those areas. Concentration ranges of tritium in fresh river water, brackish lake and seawater samples were 0.60 to 1.1 Bq^. l^-1(mean value 0.79 Bq^. l^-1), 0.20 to 0.87 Bq^. l^-1(mean value 0.41 Bq^. l^-1), and 0.08 to 0.25 Bq^. l^-1(mean value 0.15 Bq^. l^-1), respectively. Relationships between tritium concentrations and salinity in the samples showed a clear negative correlation. Moreover, the seasonal variation of tritium in water from Rokkasho-Village was high in spring and low in fall.     

Barriers to nitrogen inversion in 6-membered rings : Nitrogen inversion in tetrahydro-1,2-oxazines

A study of the nitrogen inversion process in the bicyclic oxazine, N-methyl-2-oxa-3-azabicyclo[2,2,2]octane, by ¹³C NMR spectrocopy reveals a free energy of activation of 14.9 kcal mole^-1. Detailed examination of the kinetics of the process observed in the ¹H spectra of N-methyl tetrahydro-1,2-oxazine shows ΔH^≠ 15.1±0.4 kcal mole^-1 and ΔS^≠ 2.3 ±1.5 cal mol^-1K^-1. It is concluded from the similarity in the activation parameters that both processes arise from nitrogen inversion.     

Physical and chemical investigation of water and sediment of the Keban Dam Lake, Turkey:

Summary The gross alpha- gross beta-activity, ¹³⁷Cs and ⁹⁰Sr in the water and sediment samples taken from the Keban Dam Lake, Uluova Region, was investigated in 2003 and 2004. We have found that in spring the concentration of ¹³⁷Cs in the surface water and deep sediment changed between 0.001-0.01 Bq/l (0.4-2.5 Bq^.kg^-1) that of ⁹⁰Sr between 0.0001-0.009 Bq/l (0.1-9 Bq^.kg^-1) and in autumn the values were 0.0001-0.009 Bq/l (0.4-8 Bq^.kg^-1) for ¹³⁷Cs and 0.0002-0.005 Bq/l (0.6-4 Bq^.kg^-1) for ⁹⁰Sr, respectively. The results were presented in form of iso-curves.     

Determination of 210Pb activity concentration in ground-level air by gamma-ray spectrometry in Tripoli, Libya

²¹⁰Pb activity concentration at ground-level air of Tripoli was determined by gamma-ray spectrometric analysis of 20 particulate samples collected. Each sample, the air filtered through chlorinated vinyl polychloride Petrianow was 78,000 m³ on average. Activity concentrations of ²¹⁰Pb were ranging from 78-186 mBq^.m^-3. Estimated effective dose to adult from inhaled ²¹⁰Pb was calculated to be 2.7 mSv^.y^-1.     

Influence of natural sorbents on the immobilization of spent ion exchange resins in cement

Summary Leach characteristics of ¹³⁷Cs and ⁶⁰Co radionuclides from spent mix bead ion exchange resins and both ordinary Portland cement and cement mixed with two kind of natural sorbents (bentonite and clinoptilolite) have been studied using the International Atomic Energy's (IAEA) standard leach method. The waste immobilization performance of low-level wastes in natural sorbent mixtures was determined. The solidification matrix was a standard Portland cement mixed with 290-350 (kg/m³) spent mix bead exchange resins, with or without 1-10% of bentonite or/and clinoptilolite. The leaching rates from the cement-bentonite matrix were measured after 300 days as ⁶⁰Co: (1.20-9.72) ^. 10^-5 cm/d and ¹³⁷Cs: (1.00-9.22) ^. 10^-4 cm/d. From the leaching data, the apparent diffusivity of cobalt and cesium in cement-bentonite or/and clinoptilolite matrix with a waste load of 350 kg/m³ of spent mix bead exchange resin was calculated as ⁶⁰Co: (1.0-5.9) ^. 10^-6 cm²/d and ¹³⁷Cs: (0.48-2.4) ^. 10^-4 cm²/d. The compressive strength of these samples is determined according to the ASTM standards.     

Determination of copper with neocuproine by thermal-lens spectrometry

Conditions for the spectrophotometric determination of copper with 2,9-dimethyl-l,10-phenan-throline (neocuproine) in the presence of ascorbic acid in a water-ethanol solution (9 : 1) at pH 4.5–5.0 have been found. The detection limit is 3 x 10^-6 M. The concentration range is from 4.4 x 10^-6 to 3 x 10^-4 M. Conditions for the determination of copper(I) with neocuproine by thermal lens spectrometry have been proposed. The detection limit is 4 x 10^-7 M. The concentration range is from 7 x 10^-7 to 6 x 10^-5 M. Iron(II) at concentrations as high asn x 10^-4 M does not interfere with the determination of copper. Changes in the conditions for the photometric reaction associated with passing from spectrophotometric measurements to thermal lensing are discussed.     

Heat capacities and absolute entropies of UTi<Subscript>2</Subscript>O<Subscript>6</Subscript> and CeTi<Subscript>2</Subscript>O<Subscript>6</Subscript>

Summary As part of a larger study of the physical properties of potential ceramic hosts for nuclear wastes, we report the molar heat capacity of brannerite (UTi₂O₆) and its cerium analog (CeTi₂O₆) from 10 to 400 K using an adiabatic calorimeter. At 298.15 K the standard molar heat capacities are (179.46±0.18) J K^-1 mol^-1 for UTi₂O₆ and (172.78±0.17) J K^-1 mol^-1 for CeTi₂O₆. Entropies were calculated from smooth fits of the experimental data and were found to be (175.56±0.35) J K^-1 mol^-1 and (171.63±0.34) J K^-1 mol^-1 for UTi₂O₆ and CeTi₂O₆, respectively. Using these entropies and enthalpy of formation data reported in the literature, Gibb’s free energies of formation from the elements and constituent oxides were calculated. Standard free energies of formation from the elements are (-2814.7±5.6) kJ mol^-1 for UTi₂O₆ and (-2786.3±5.6) kJ mol^-1 for CeTi₂O₆. The free energy of formation from the oxides at T=298.15 K are (-5.31±0.01) kJ mol^-1 and (15.88±0.03) kJ mol^-1 for UTi₂O₆ and CeTi₂O₆, respectively.     

Synthesis of 1-(4-methylsulfone-phenyl)-5-(4-fluoro-phenyl)-5-[14C]-1,2,3-triazole and 1-(4-sulfonamide-phenyl)-5-(4-fluoro-phenyl)-5-[14C]-1,2,3-triazole as novel carbon-14 anticonvulsant

Summary Two 1,2,3-triazole anticonvulsants, 1-(4-methylsulfone-phenyl)-5-(4-fluoro-phenyl)-5-[¹⁴C]-1,2,3-triazole and 1-(4-sulfonamide-phenyl)-5-(4-fluoro-phenyl)-5-[¹⁴C]-1,2,3-triazole, both labeled with carbon-14 in the 5-position were prepared from para-fluoro-benzonitrile-[cyano-¹⁴C].     

Radionuclides in a sediment trap and bottom sediment samples from the eastern Turkish coast of the Black Sea

Summary Radionuclide (¹³⁷Cs, ²³⁸U, ²³²Th and ⁴⁰K) concentrations were determined in a sediment trap and bottom sediment samples collected from a station at the eastern Turkish coast of the Black Sea. The specific activity of the ¹³⁷Cs radionuclide in the settling particles ranged from 0.04±0.01 to 0.10±0.02 Bq^. g^-1dry weight. The calculated flux rate of the ¹³⁷Cs was between 0.37 and 2.59 Bq^. m^-2. d^-1in the sampling periods of 2002 and 2003. The ¹³⁷Cs concentration in the bottom sediment profile were between 0.039±0.013-9.083±0.017 Bq^. g^-1dry weight in the same station. The vertical profile of the radionuclides suggests that they have little mobility during the 17 years after the Chernobyl accident.