Effect of neutralizing agent content on137Cs leaching from solidified boric acid waste products

For the preservation of environment from radioactive contamination, one of the properties necessary for solidified radioactive wastes is resistance to the release of radionuclides due to leaching by ground water after land disposal. In order to seek the optimum solidifying formulation for cement solidified boric acid concentrate from pressurized water reactor, a variety of specimens were prepared, varying the content of neutralizing agents and neutralization methods. For the leaching measurements, the ANS 16.1 Standard Leach Test was carried out for the specimens which had been mixed with small concentration of¹³⁷Cs to estimate the leachability index. According to our investigation, the optimum contents of neutralizing agents for neutralization of boric acid radioactive waste were determined in view of resistance ability to leaching. Eventually the leachability indices have turned out to be 5.807.91 depending on the formulations.     

Screening of plant species for comparative uptake abilities of radioactive Co, Rb, Sr and Cs from soil

In case of radioactive fallout, persistence of long lived nuclides in soil and subsequent transfer into the food chain through plants over a long period is the key factor. The possibility of phytoremediation is suggested to reduce the radionuclides in soil. To exploit the natural potential of some plants in absorbing or accumulating certain radionuclides and depleting the soil radioactivity, thirty-two plant species were tested under laboratory conditions for their comparative ability in taking up radioactive Rb, Co, Sr and Cs. Broccoli and tomato for Co, tomato, chard, sunflower and cucumber for Rb; cucumber, sunflower and turnip (Kyona) for Sr, and tomato, chard and cucumber for Cs were found to be effective compared to other species tested.     

Deposition of fission product radionuclides in lichens and coniferous plants in Turkey

The effects of the Chernobyl disaster on lichens and pines, which are widely distributed in northern and western Turkey, have been examined within the four years between 1986–1990. Analyses of the plants studied by -spectrometry and spectrophotometric techniques have shown that the highest radioactive pollution was observed in the Pseudevernia furfuracea. The effects of Chernobyl on the ecosystem have been examined by comparing different plant species from the point of view of their reception and accumulation of fallout radionuclides.     

Separation of63Ni traces from low and medium level radioactive wastes produced during the operation of nuclear power reactors

The classification of low and medium level radioactive wastes produced regularly by nuclear power plants is becoming ever more important in Mexico, after a few years of running the first of two units, 600 MeV each, in Laguna Verde nuclear power plant. This paper describes a method to separate and detect traces of the weak -emitter⁶³Ni, which is one of the activation products used to classify low and medium level radioactive wastes originating from the operation of nuclear power plants.     

Did the radioactive contamination in Hungary due to the disaster at the Chernobyl nuclear power station had a biopositive effect on plants?

Due to the disaster at the Chernobyl nuclear power station /26.04. 1986, USSR/ the radioactive contamination level /e.g.,¹³⁴Cs,¹³⁷Cs/ of the biosphere in Hungary increased significantly. The external -dose burden from the contaminated ground surface and atmosphere, and the radioactive isotopes taken up directly through the leaves and indirectly from the soil through the root system had a low-dose effect on the plants which was in the dose-range of stimulation /biopositive effect/.     

Determination of radioactive nuclides of uranium and thorium series and estimation of α-flux in LSI constituent materials

Gamma-rays of nuclides of uranium and thorium series in silicone resin and ceramics were measured with a Ge(Li) detector. The state of radioactive equilibrium was determined by comparing the concentrations of uranium and thorium with the radioactive concentrations of²¹⁴Pb and²¹²Pb. The radioactive equilibrium was attained in silicone resin but not in ceramics. The -flux was calculated from the concentrations of uranium and thorium and their daughter nuclides. The calculated values of -flux agreed with that of -flux measured.     

Separation of strontium from calcium by means of anion exchanger and alcoholic solution of nitric acid

A possibility of mutual separation of calcium and strontium on an anion-exchange column has been studied and then used in working out methods of separation of radioactive strontium from natural samples. All examinations, carried out on model systems, showed that calcium could be completely separated from strontium on the column with the anion exchanger Amberlite CG-400 using 0.25M HNO₃ in methanol as eluent. The flow velocity of this eluent in the range between 1 ml/min and 5 ml/min did not influence the efficiency of separation of calcium from strontium. The increase of the concentration of nitric acid in methanol reduced the efficiency of their mutual separation and the increase of exchanger column height neutralized the influence of the increase of acid concentration. Calcium was separated from strontium in the mass concentration ratio (Ca²⁺)/(Sr²⁺) in the range between 11 to 1001. This separation procedure may be used for the isolation of radioactive strontium from real samples instead of using fuming nitric acid.     

Iodine determination in biological materials by ICP-MS

The present work describes an analytical procedure for the determination of the total iodine content in biological materials (serum, milk, plants, tissues etc.). Liquid samples can be directly analyzed after dilution, if necessary, by ICP-MS. Milk powder, plants and tissues were dissolved by using a modified simple Schöninger combustion, subsequently the residue was taken up in 0.1 mol/l NaOH and this solution was analyzed by ICP-MS. The detection limit is in the range of 0.01 g/l. The method was tested using different CRMs certified for the iodine content.     

Expanded porphyrins: functional photoacoustic imaging agents that operate in the NIR-II region

Photoacoustic imaging (PAI) relies on the use of contrast agents with high molar absorptivity in the NIR-I/NIR-II region. Expanded porphyrins, synthetic analogues of natural tetrapyrrolic pigments (e.g. heme and chlorophyll), constitute as potentially attractive platforms due to their NIR-II absorptivity and their ability to respond to stimuli. Here, we evaluate two expanded porphyrins, naphthorosarin (1) and octaphyrin (4), as stimuli responsive PA contrast agents for functional PAI. Both undergo proton-coupled electron transfer to produce species that absorb well in the NIR-II region. Octaphyrin (4) was successfully encapsulated into 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) (DSPE-PEG₂₀₀₀) nanoparticles to afford OctaNPs. In combination with PAI, OctaNPs allowed changes in the acidic environment of the stomach to be visualized and cancerous versus healthy tissues to be discriminated.

In this study, two expanded porphyrins, octaphyrin and naphthorosarin were evaluated as potential PA agents. The nanoparticle encapsulation of octaphyrin successfully enabled the visualization of acidic environments and the discrimination between cancerous and healthy tissues.     

Radium accumulation in animal thyroid glands a possible method for uranium and thorium prospecting

A method of prospecting for uranium and thorium is proposed based on uptake of their radioactive daughters²²⁶Ra and²²⁸Ra by plants, the collection of plant material by herbivores, the concentration of the radioactive species by specific animal tissues, and the subsequent gamma-ray analysis of the tissues. This paper is based on work performed under United States Energy Research and Development Administration (formerly U.S.A.E.C.), Contract EY-76-C-06-1830.     

A comparative study on environmental radioactivity in shellfish inhabiting the coasts of Korea and Japan

To examine inshore radioactive contamination caused by nuclear power plants, both gross -radioactivity and -spectrometry was measured. The measurements were taken with the sea mussels, Mytilus coruscus and Mytilus edulis, which had been collected from the four different sites of nuclear power plants (Kori, Ulchin, Wolsong, and Younggwang), and Cheju-do as a control site. As a result, the gross -radioactivity observed was similar to that in nature. Among radionuclides, only¹³⁷Cs,²⁰K,⁷Be and⁶⁰Co were detected in a very small amount, and each was also close to the natural levels.     

Determination of uranium and thorium concentration in some Egyptian rock samples

Uranium (U) and thorium (Th) isotopes and their several radioactive descendants found in soil, rock, water, plants, air, etc., contribute to the natural radiation exposure of the population. Phosphate rocks are really rich natural sources of uranium and thorium among the other minerals forming the earth's crust. U and Th concentrations in some Egyptian phosphate samples were determined using a nuclear track registration methodology and -ray spectroscopy. The resulting latent tracks from all -decaying isotopes in both U and Th series were recorded in plastic detectors. A uniquely sensitive polycarbonate CR-39 nuclear detector was used. Results showed that the U and Th concentration in the samples studied range from about 4.0 up to 35.0 ppm and from 11.0 to 124.0 ppm, respectively. Results are discussed within the frame work of track formation methodology in plastic and -ray spectroscopic analysis.     

Synthesis of antitumoral agents from podophyllotoxin

Syntheses based on podophyllotoxin have led to the inclusion among antitumoral agents valuable in practice of the preparations etoposide(I) and teniposide(II). These compounds are, respectively, the 4,6-ethylidene and 4,6-thenylidene derivatives of 4-dimethylepipodophyllotoxin -D-glucopyranoside. A review has been made of methods of synthesizing (I) and (II) and for their experimental investigation. Some conclusions are given from the results of clinical trials. Although (I) and (II) have been accepted for practical use, their clinical activity is limited. The principles of the experimental selection of antitumoral agents are considered particularly. Considerations are expressed concerning the possibilities of improving the results of the search for antitumoral agents of plant origin.All-Union Oncological Scientific Center of the USSR Academy of Medical Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 638–652, September–October, 1987.     

Production of Titanate Microspheres by Sol-Gel and Spray-Drying

Porous titanate precursor microspheres (20–60 m in diameter), with a high sorption capacity for radioactive wastes from nuclear reprocessing plants, have been produced on a 50 kg scale by spray-drying precursor sols. Well-dispersed, stable sols were produced by hydrolyzing acetic acid modified tetraisopropyltitanate and peptizing the titania hydrolysate with acidic zirconia sol. The resulting TiO2 /ZrO2 sols were routinely concentrated to 900 g dm–3 (oxide basis) and exhibited excellent stability. These sols were subsequently mixed with dispersible alumina powder and partially aggregated by adding calcium and barium nitrate salts. The resulting sols were spray-dried to produce microspheres with controlled porosity and morphology. The properties of the spray-dried powder were very dependent upon the chemical properties of the precursor sol. In particular, hollow spheres were produced from well-dispersed sols, whereas solid spheres could be produced from partially-aggregated sols.     

Controlled pesticide release from biodegradable polymers

Polymers have been widely used in agriculture for applications including controlled release of pesticides and other active ingredients. The ability to predict their delivery helps avoid environmental hazards. Macromolecular matrices used as carriers in controlled release of agricultural active agents, especially pesticides, are reviewed. The review focuses on the advantages and mechanisms of controlled release. It includes biodegradable polymers in agriculture, their manufacturing methods, and their degradation mechanisms and kinetics. The article also presents a critical account of recent release studies and considers upcoming challenges.      

Actinide uptake onto zeolite-L and SAPO-34

The characteristics of ion exchange of uranyl and americium, which are -emitting radioactive nuclides, were examined by batch and column methods. SAPO-34 showed good selectivity for uranyl ion at pH 2–3.5, and distribution coefficients of Am³⁺ and UO ₂ ²⁺ increased with equilibrium pH. -irradiation (2 MGy) did not show any significant effect on the uptake of both of actinide ions onto L and SAPO-34. Higher does of -irradiation (up to 10 MGy) created a change of equilibrium pH, and hence uptake, due to radiolysis of water and heat localization generated by -radiation and annealing processes.     

Fluorescence detection techniques for protein kinase assay

Traditional methods for protein kinase (PK) assay are mainly based on use of ³²P-labeled adenosine triphosphate (ATP); applications of such methods are, however, hampered by radioactive waste and short half-life of ³²P-labeled ATP. Therefore non-radioactive methods, such as fluorescence detection techniques are good alternative. In this review, we describe the principles of four fluorescence techniques (fluorescence intensity endpoint measurement, fluorescence resonance energy transfer (FRET), fluorescence polarization (FP), and fluorescence lifetime imaging) and provide an overview of applications of these fluorescence detection techniques in protein kinase assay, underlining their relative advantages and limitations. Research trends in this field are also highlighted. Figure Schematic representation of kinase assay based on direct fluorescence polarization measurements. The fluorescent peptide, on phosphorylation by kinase, binds to a phosphospecific antibody, which leads to a high FP value     

The chemical composition of mixed wastes: Analysis of the photolysis products of organic ligands

A survey of the literature regarding the composition of mixed wastes originating from the clean ups of spills of radioactive solutions shows that (1) the mixtures obtained in studies of the X-ray and -ray radiolysis, and of the UV-photolysis of organics in aqueous solutions have very similar composition provided the photolysis is carried out with UV beams with wavelengths below 242 nm; (2) the composition of the organic fraction of mixed wastes containing initially EDTA, NTA, and/or citric acid is complex. The mass recoveries are between 20 and 60%; and (3) the UV-photolysis of complexing agents gives much more complex mixtures at high pH than at low pH, because carbonyl compounds are formed, and these compounds undergo complex series of reactions in strongly alkaline solutions. The mixed wastes considered have a high pH due to the necessity of complexing strongly the heavy metals involved in spills. These results are confirmed by an investigation of the properties of the products of the UV-irradiation of EDTA, citric acid and some of their binary mixtures. The products of the esterification by BF₃/BuOH are only partly soluble in methylene chloride. Much better yields are obtained by using BF₃/BuOH as the reagent.¹³C NMR illustrates the composition of the mixture, without requiring a separation and is useful to follow the fate of compounds during their methylene chloride extraction after esterification.     

Determination of the ratio of the hydrogen and manganese absorption cross sections by the manganese bath technique

The ratio of the hydrogen and manganese neutron absorption cross sections, _H/_Mn, is a most important parameter in the determination of radioactive neutron source strength by the manganese bath technique. The ratio is well measured by observing the change in⁵⁶Mn activity induced in the manganese bath by a fixed neutron source as the manganese concentration of the bath is changed. In the present study, the neutron source was a Maxwellian beam from²⁵²Cf. Concentrations were determined by the two methods: volumetric and gravimetric. The cross section ratio has turned out to be _H/_Mn=0.02506.