Preparation and preliminary evaluation of <Superscript>211</Superscript>At-labeled amidobisphophonates

In this paper, 3-amino-1-hydroxypropylidene-1,1-bisphosphonate(APB), a amidobisphophonate was synthesized and labeled with the α-emitter ²¹¹At by an indirect method using N-succinimidyl 5-(tributylstannyl)-3-pyridinecarboxylate (SPC) as a bi-functional linker, and the conjugated amidobisphophonate (²¹¹At-SAPC-APB) was preliminarily evaluated in vitro and in vivo by comparison with free astatide (²¹¹At⁻) and ^99mTc-MDP. 3-amino-1-hydroxypropylidene-1,1-bisphosphonate(APB) was prepared using β-alanine as the starting material. With SPC bi-functional linker, APB was conjugated with ²¹¹At in a labeling yield of 80–90% with radiochemical purity of more than 99%. The conjugated amidobisphophonate (²¹¹At-SAPC-APB) exhibited considerable stability in vitro, in that the radiochemical purity of ²¹¹At-SAPC-APB was still more than 98% in 0.1 mol/L PBS (pH 7.6) or in fetal calf serum, even stayed for 24 h at room temperature (RT). Biodistribution of ²¹¹At-SAPC-APB was investigated in NIH strain mice by I.V injection. The results showed that ²¹¹At-SAPC-APB could rapidly locate in shank, with the maximum uptake of 23.70 ± 2.29% I.D/g at 6 h, earlier than that of ^99mTc-MDP at 12 h, and stayed in the bone for long time. Moreover, ²¹¹At-SAPC-APB uptake in some key organs or tissues, especially in thyriod, stomach, lung and spleen, was much less than that of free astatide (²¹¹At⁻), implying that ²¹¹At-SAPC-APB was constantly stable in vivo as well as in vitro. These results indicated that ²¹¹At-SAPC-APB will be a suitable candidate for the targeted radiotherapy of bone metastases and should be further investigated.     

Corrosion study of heat exchanger tubes in pressurized water cooled nuclear reactors by conversion electron Mössbauer spectroscopy

A first attempt to label insulin, a small protein with significant affinity to tumors with the α-emitter ²¹¹At was performed by an indirect method using N-succinimidyl 5-(tributylstannyl)-3-pyridinecarboxylate (SPC) as a bi-functional linker, and the stability of the conjugated insulin (²¹¹At-insulin) was evaluated in vitro and in vivo. SPC was synthesized by using 5-bromonicotinic acid as the starting material. With this bi-functional linker, insulin was conjugated with ²¹¹At in a labeling yield of 30–40%, with radiochemical purity of more than 98%. After 24 hours at room temperature, the radiochemical purity was still more than 95%, implying that ²¹¹At-insulin is fairly stable in vitro. Biodistribution of ²¹¹At-insulin was investigated in NIH strain mice. ²¹¹At accumulated rapidly in the liver post injection, with the maximum uptake of 4.29%I.D/g at 30 minutes, and was mainly excreted by kidney. More importantly, ²¹¹At-insulin uptake in some key organs or tissues, especially in thyriod, stomach, lung and spleen, was much less than that of free astatide (²¹¹At^?). This result indicated that ²¹¹At-insulin has considerable stability in vivo as well as in vitro.     

双功能偶联剂SPC的一种新合成方法及其碘标记

放射性碘标记药物广泛用于医学检验及临床诊断和治疗中。放射性碘标记蛋白质不管是采用Ch-T、Iodogen直接标记方法还是采用Bolton-Hunter试剂间接标记方法,其存在的主要问题是标记物可能在体内严重脱碘[1,2]。为了克服这一问题,人们不断改进碘标记方法。其中,Zalutsky、W ilbur     

Cs and Sr removal from solution using potassium nickel hexacyanoferrate impregnated zeolites</p> </p>

Summary Potassium nickel hexacyanoferrate, KNiFC, was incorporated in the porous matrix of zeolites by successive impregnation with Ni(NO₃)₂ and</o:p></p> K₄Fe (CN)₆.¹ CFC and PFC exchangers were first prepared by impregnating the potassium nickel hexacyanoferrate into the clinoptilolite and the synthetic P zeolite, respectively. Ion-exchange isotherms and breakthrough curves were plotted. Results showed that the CFC sorbent is suitable for removal of Cs⁺ where PFC is more suitable for Sr²⁺. Negative effect of Na⁺ as a competing ion in these exchangers was less than in the parent zeolites. Isotherm plots fitted the Langmuir equation.</p> </p>     

Sorption of Co, Cs, Sr and I onto argillaceous rock as studied by radiotracers</p> </p>

Summary Sorption of⁶⁰Co,⁸⁵Sr, 137Cs and¹²⁵I have been studied on samples originated from Boda (siltstone-) claystone formation (BCF) (Hungary). The distribution of K_dvalues have been determined in static batch experiments using natural groundwater. The order of sorption of isotopes was Co>Cs>Sr>I, where iodine exhibits sorption properties in a modest extent. The sorption isotherm was determined for Cs from measurements carried out in 10^-5-10^-1M initial concentration range. The isotherm can be described with non-linear Freundlich approximation in the range of</o:p></p> 10^-7-10^-4M equilibrium concentration. At concentrations >10^-2M the isotherm achieves saturation. Hence, it is suggested that sorption of Cs on BCF is dominated by cation-exchange reactions on the illite mineral component. In the case of Co and Sr, precipitation reactions occurred during the experiments performed with carrier-containing solutions. This can be attributed to the low values of solubility product constants of SrCO₃, SrSO₄and Co(OH)₂, formed from anions present in the natural groundwater.</p> </p>     

Mathematical modeling of separation of microamounts of strontium from yttrium in water - HCl -nitrobenzene - 15-crown-5 - hydrogen a dicarbollylcobaltate extraction system</p> </p>

Summary A rapid separation of microamounts of Sr²⁺ from Y³⁺ using HCl, 15-crown-5 (15C5) and hydrogen dicarbollylcobaltate (H⁺B^-) in the two-phase water - nitrobenzene extraction system was developed. The reached separation factor a(Sr/Y) was approximately 10. ^5.4</p> __</p>     

Preconcentration of 198Au in a green alga, Rhizoclonium</p> </p>

Summary The bioaccumulation of ¹⁹⁸Au radionuclide, by Rhizoclonium riparium a member of Chlorophyceae has been studied. It has been observed that accumulation of gold on Rhizoclonium is almost pH independent and slightly higher at basic pH. Accumulation of gold was studied with ¹⁹⁸Au radiotracer, 0.1, 1 and 5 ppm concentrations of gold. It has been concluded from the biochemical analysis that the gold accumulation is due to adsorption in the cellulose and not in protein, fat and carbohydrate. Accumulated gold was recovered when washed with conc. HNO₃.</p> </p>     

Radiation effects on gaseous iodine at very low concentrations</p> </p>

Summary Exploratory experiments have been carried out to investigate the effects of gamma-radiation on iodine aerosols under various chemical conditions. The results indicate that iodide ions (I^-) in aerosol can be readily oxidized to I₂ and HIO, and some iodide ions may be converted to organic iodine when organic additives are present in the KI solution from which the aerosol is generated. The results also suggest that the chemical transformation of irradiated iodine aerosol depends on the chemical environment both carrier gas and iodide solution.</p> </p>     

Factors affecting the sorption of Eu(III) on modified silica gel</p> </p>

Summary 8-Hydroxyquinoline in benzene, xylene, chloroform and toluene diluents was used to modify silica gel as a solid phase extractant (SPE) for the sorption of Eu(III) in batch extraction techniques. Influences of solid/liquid ratio, pH, metal ion concentration, particle size and temperature were studied. The optimum initial pH is 4.2, while the maximum sorption capacities for the prepared impregnated resins in benzene, xylene, chloroform and toluene diluents are 18.52, 14.98, 14.79 and 5.94 mg ^. g^-1, respectively. The sorption process is found to be affected by both metal ion concentration and particle size of the impregnated resin. Thermodynamic parameters for the sorption of Eu(III) were determined and the reaction is found to be exothermic and spontaneous with enthalpy-14.23 and-23.71 kJ ^. mol^-1 for benzene and xylene as diluents. Release of the element from the loaded solid particles into 0.01M HNO₃ is@85% and@53% from 8-HQ/benzene/silica gel and 8-HQ/xylene/silica gel.</p> </p>     

Mixed-valence state of optically active 1',1'”-bis(2-phenylpropyl)-1,1”-biferrocenium salts</p> </p>

Summary The mixed-valence state of 1',1'”-bis(2-phenylpropyl)-1,1”-biferrocenium polyiodides was studied for (R,R), (S,S), (R,S) isomers and the DL modification. The effect of cation symmetry appeared differently from 1',1'”-bis(2-phenylbutyl)-derivatives, while similar packing effect was observed.</p> </p>     

Cation-exchange separation of uranium from thorium in nitric acid medium</p> </p>

Summary Sorption behavior of Th and U on cation-exchange resins was investigated from nitric acid medium by both batch and column methods. The cation-exchange studies involved the sorption of UO₂²⁺ and Th⁴⁺ and their cationic complexes onto Dowex 50Wx8 and Dowex 50Wx4 resins (50-100 mesh). The batch data yielded a separation factor (K_d,Th/K_d,U) value of >100 for the cation-exchanger, Dowex 50Wx4 at 1-2M HNO₃. Separation of uranium from thorium was also carried out by column method in nitric acid medium using cation-exchangers, Dowex 50Wx4 as well as Dowex 50Wx8. While uranium elution was possible at 1M HNO₃, Th could be eluted only at higher concentration of nitric acid (>6M). The stripped solution emanating from a mixer settler employing di-2-ethyl hexyl isobutyramide as extractant and feed solution similar to THOREX process comprising 350 mg/l U and 380 mg/l Th in 0.75M HNO₃ was loaded on the column and the decontamination factor value for U in the product was >1000.</p> </p>     

Liquid-liquid extraction of 233Pa(V) with Aliquat 336</p> </p>

Summary The extraction of protactinium with Aliquat 336 (methyl-tri-caprylyl ammonium chloride) in toluene, cyclohexane and chloroform from HCl, HNO₃, H₂SO₄, HClO₄, HF and mixed HCl-HF media was investigated by radioactive tracer technique. Distribution ratios of protactinium between the aqueous solution and the organic phase were determined as a function of shaking time, concentrations of acid in aqueous solution phase, extractant concentration and type of diluents in the organic phase. Aliquat 336 can almost quantitatively extract protactinium from strong HCl solution. At the same time, small amounts of HF in HCl solutions have a strong effect on Pa distribution.</p> </p>     

Selective separation of uranium using trimethylammonium acetosalycoylhydrazone modified Duolite C20 resin</p> </p>

Summary Duolite C20 resin modified with trimethylammonium acetosalycoylhydrazone has been developed, for the selective separation and/or preconcentration of uranium. The modified resin was characterized by elemental analysis and infrared spectra. Batch and column modes were applied. The newly designed resin quantitatively sorbs uranium ion at pH 3 when the flow rate equals to 2 ml ^. min ^-1 . The sorption capacity was 0.750 mmol ^. g^-1 for uranium ion, whereas its preconcentration factor was 200. The lower limit of detection was 5 ng ^. ml^-1 and its desorption was effective with 5 ml of 3 mol ^. l^-1 HCl or HNO₃ prior to detection spectrophotometry. The modified resin was highly ion-selective in nature even in the presence of large concentrations of electrolyte or organic media, with a preconcentrating ability for uranium ion. The modified resin was tested on its utility with synthetic, real and certified ore samples, showed RSD values of <2% reflecting the accuracy and reproducibility of the newly modified resin.</p> </p>     

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>     

Removal of uranyl ions from wastewaters using cellulose and modified cellulose materials</p> </p>

Summary Three silylcellulosic derivatives with different substitution degree were examined as sorbents for uranyl ions. The adsorption rate and capacity of cellulose and modified cellulose were investigated in aqueous media, at various pH and temperature values. The polymer - metal complexes of UO₂²⁺ were characterized by infrared and electronic spectra, and thermogravimetry. The thermal behavior of cellulose (C), trimethylsilyl - cellulose (tmsc, SD= 2.85) and triphenylsilyl - cellulose (TPSC1, SD=2.89 and TPSC2, SD =2.70) and their complexes with uranyl ions in atmospheric air has been studied between room temperature and 600 °C. The Coats-Redfern method was applied to estimate the kinetic parameters. The results revealed that the complexation of C and TMSC with UO₂²⁺ increases the thermal stability.</p> </p>     

Recovery of technetium adsorbed on charcoal</p> </p>

Two methods capable of near complete recovery of technetium adsorbed on charcoal are presented. The first involves liquid extraction of the technetium from the charcoal by hot 4M nitric acid. An average recovery of 98% (n=3) is obtained after three rounds of extraction. The second method involves dry ashing with air in a quartz combustion tube at 400-450 °C. This method yields an average recovery of 96% (n=5). Other thermal methods were attempted, but resulted in reduced recovery and incomplete material balance.</p> </p>     

Diffusion of Sr, Cs, Co and I in argillaceous rock as studied by radiotracers</p> </p>

Summary Diffusions of⁸⁵Sr,¹³⁷Cs,⁶⁰Co and¹²⁵I radionuclides have been studied in borecore samples from Boda siltstone/claystone formation (BCF) under ambient and in situ conditions. In-diffusion (⁸⁵Sr,¹³⁷Cs,⁶⁰Co and¹²⁵I) and through-diffusion measurements (¹²⁵I) were performed at ambient conditions, and for iodine, in-diffusion measurements were also carried out at in situ conditions (100 bar, 50 °C). In the case of cationic species carrier-containing solutions were also applied.⁶⁰Co was detected only in the first slice of borecore at each sample, while¹³⁷Cs was detected also in the first-, second- and third slices according to the concentration-increase of inactive carrier. Among the investigated cations,⁸⁵Sr exhibited the fastest diffusion rate with 2.7-6.0 ^. 10^-12m²/s apparent diffusivity values. In the course of in-diffusion measurements 4.7 ^. 10^-11 m ² /s, during through-diffusion investigations 1.4-1.6 ^. 10^-12m²/s and at in situ conditions 5.0-8.0 ^. 10^-12 m²/s apparent diffusivities were obtained for¹²⁵I.Modest sorption of¹²⁵I can also be deduced from the results.</p> </p>     

Strontium isolation from natural samples with Sr resin and subsequent determination of 90Sr</p> </p>

The reliability of an ⁹⁰Sr determination method was tested using an Sr extraction chromatographic resin for strontium isolation. The ⁹⁰Sr-content in samples of vegetables, soil and water (obtained from Environmental Measurement Laboratory, USA) were determined and the results were controlled by classical methods and by using an anion-exchanger and an alcohol solution of nitric acid for the strontium isolation. These methods were previously tested by determining ⁹⁰Sr in IAEA 326 and 327 samples of soil. It is shown that the isolation process with Sr resin is simpler and faster than the classical and mixed solvent anion-exchange methods. The efficiency of isolation on a Sr column depends on the resin quantity and separation conditions; and is the highest with a Sr column, compared to the classical and anion-exchange methods. Experimental data and theoretical models were used to calculate the parameters that enable the estimation of optimum dimensions of the column for isolation. A simple relation is proposed for the calculation of breakthrough volume, which defines the sample and eluent volumes for an optimal strontium isolation.</p> </p>     

Cascade ultrafiltering of 210Pb and 210Po in freshwater using a tangential flow filtering system</p> </p>

Summary A rapid method was developed using ultrafilters with a tangential flow filtering system for molecular size separation of naturally occurring ²¹⁰Pb and ²¹⁰Po in a freshwater sample. Generally, ultrafiltering of a large volume water sample for measuring the nuclides was too time consuming and not practical. The tangential flow filtering system made the filtering time short enough to adapt for in-situ ultrafiltering the large volume sample. In this method, a 20 liter water sample was at first passed through the 0.45mm pore size membrane filter immediately after sample collection to obtain suspended particle matter [>0.45mm particulate fraction (PRT)]. Two ultrafilters (Millipore Pellicon 2^ò) were used sequentially. The nuclides in the filtrate were separated into three fractions: high molecular mass (100 kDa-0.45mm; HMM), low molecular mass (10 k-100 kDa; LMM) and ionic (<10 kDa; INC) fractions. It took 80 minutes to process the sample after collection. The cut-off molecular size of each ultrafilter was confirmed by size exclusion chromatographs (SEC) of the LMN and the HMM fractions. Adsorption of the nuclides and organic compounds in the sample onto the ultrafilters was negligibly small. Good reproducibility of the nuclide concentrations in each fraction was confirmed by repeated experiments. The method was successfully applied to obtaine the molecular size distributions of ²¹⁰Pb and ²¹⁰Po in an oligotrophic lake, Lake Towada located in the northern area of Japan.</p> </p>     

Radiological hazard and radiogenic heat production in some building materials in upper Egypt</p> </p>

Summary Samples of limestone, sand, marble, clay brick, red brick, gypsum, Portland cement and white cement collected from upper Egypt used in building manufacturing have been analyzed for the natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K usingg-ray spectrometry. The specific concentrations for ²²⁶Ra, ²³²Th and ⁴⁰K, ranged from 20-88, 13-115 and 54-304 Bq/kg, respectively. The average specific activities of these radionuclides were compared. Higher values of ²²⁶Ra and ²³²Th could be noticed in marble while that of ⁴⁰K was in red bricks. Radium equivalent activities, dose rate and the annual gonadal dose equivalents AGDE were calculated for the measured samples to assess the radiation hazard arising from using those materials in the construction of dwellings. The radioactive heat production values of the selected materials have also been determined. They vary from a minimum of 0.41 for white cement to a maximum of 5.52mW/m³ for marble samples. The calculated heat-production values are quite similar to those estimated in Corsica.</p> </p>