Radioactive Salts Research Articles

Functionalization of filled radioactive multi-walled carbon nanocapsules by arylation reaction for in vivo delivery of radio-therapy.

Functionalized multi-walled carbon nanotubes (MWCNTs) containing radioactive salts are proposed as a potential system for radioactivity delivery. MWCNTs are loaded with isotopically enriched 152-samarium chloride (152SmCl3), the ends of the MWCNTs are sealed by high temperature treatment, and the encapsulated 152Sm is neutron activated to radioactive 153Sm. The external walls of the radioactive nanocapsules are functionalized through arylation reaction, to introduce hydrophilic chains and increase the water dispersibility of CNTs. The organ biodistribution profiles of the nanocapsules up to 24 h are assessed in naïve mice and different tumor models in vivo. By quantitative γ-counting, 153SmCl3@MWCNTs-NH2 exhibite high accumulation in organs without leakage of the internal radioactive material to the bloodstream. In the treated mice, highest uptake is detected in the lung followed by the liver and spleen. Presence of tumors in brain or lung does not increase percentage accumulation of 153SmCl3@MWCNTs-NH2 in the respective organs, suggesting the absence of the enhanced permeation and retention effect. This study presents a chemical functionalization protocol that is rapid (∼one hour) and can be applied to filled radioactive multi-walled carbon nanocapsules to improve their water dispersibility for systemic administration for their use in targeted radiotherapy.

РАДІАЦІЙНО-ЗАХИСНІ ВЛАСТИВОСТІ УПАКОВКИ ДЛЯ КОНДИЦІЮВАННЯ СОЛЬОВОГО ПЛАВУ АЕС УКРАЇНИ

Considering that the problem of liquid radioactive waste management of Ukrainian nuclear power plants with WWER reactors is still unresolved, it is noted that the current level of scientific achievements provides grounds for creating a technology for the salt melt (SM) disposal without its processing. Since the exposure dose rate (EDR) for barrels with SM can significantly exceed the value of 5 mSv/h, the radiation-protective properties of the hypothetical packaging for conditioning of the salt melt formed by placing radioactive waste (RW) in a reinforced concrete container and its immobilization are considered. Exposure dose rate simulation was performed using the PHITS software package (Japan). The calculations were performed for a packaging consisting of 4 barrels of SM, placed in a universal protective container UZZK. Variants with different radionuclide composition of the SM, due to the duration of exposure of the SM – from 100% 137Cs to 137Cs-65%, 134Cs-15%, 60Co-20%, are considered. The specific concentration of radionuclides was taken from 5E7 to 1E9 Bq/kg. There are also 2 options for filling the voids: the first option involves filling the voids with the conditioning product of the bottom residue in the form of alkaline cement with a saline content of 25%, while the second option does not include radioactive salts in alkaline cement. The calculations showed the acceptability of the proposed conditioning of the salt melt by forming a package of 4 KRO-200 containers, universal reinforced concrete container UZZK TU U 29.2-26444970-005 and filling voids with the product of conditioning of the bottom residue in the form of alkaline cement with salinity -protective properties. A necessary condition for the implementation of practical measures for the conditioning of the salt melt accumulated in WWER reactors, followed by transfer to landfills is the corresponding changes in OSPU-2005 in terms of classification of the SM and its classification as solid radwaste.

Competitive growth and rising of bubbles in a yield stress fluid. Consequences on the macroscopic swelling of bitumen drums

The evolution kinetics of a bubble population driven by a uniform production of gas in a yield-stress fluid matrix is investigated in this paper. The context concerns the long time swelling of bitumen drums in which radioactive salts have been dispersed (salts suspensions in a bitumen matrix). Radioactivity generates uniform volume production of hydrogen by radiolysis of bitumen chains. Since the production rate of gas occurs on very long time scales (more than a hundred years), one needs to develop theoretical models to predict the material swelling. It has been shown previously that bitumen is a yield stress fluid and that, in the case of a motionless population (no migration due to buoyancy), the yield stress disturbs the classical scenario of nucleation, bubble growth and Ostwald ripening observed in a Newtonian fluid. In the present work, we consider bubbles nucleation and migration due to buoyancy and we show that the yield stress causes delays in the evolution of a bubble population and that it consequently modifies the macroscopic swelling of the material into the drums.

Ostwald ripening in a yield-stress fluid under uniform gas production

The evolution kinetics of a bubble population driven by a uniform production of gas in a yield-stress fluid matrix is investigated in the context of the long time swelling of bitumen drums in which radioactive salts have been dispersed (salts suspensions in a bitumen matrix). Radioactivity generates uniform volume production of hydrogen by radiolysis of bitumen chains. Since the production rate of gas occurs on very long time scales (more than a hundred years), one needs to set up theoretical models to predict the material swelling. It has been shown in previous studies that bitumen is a yield stress fluid. Therefore, the present work proposes to study the influence of a yield stress and of the production rate of gas on the evolution kinetics of a bubbles population. Usually, in a non-yield stress fluid and without gas creation, a supersaturation of gas leads to a scenario of germination, bubble growth and Ostwald ripening (growth of large bubbles at the expense of smaller ones). Over long times, a self-similar distribution of large bubbles is selected, independent of the initial distribution of nuclei. In this work, it is shown that there exist conditions for which the yield stress competes with the kinetics of ripening and induces hysteresis phenomena on the kinetics of bubbles distribution. The coupled effect of gas production rate and yield stress on the final population is discussed.

Modeling Solidification-Induced Stress in Ceramic Waste Forms Containing Nuclear Wastes

The goal of this work is to produce a ceramic waste form that permanently occludes radioactive waste. This is accomplished by absorbing radioactive salts into zeolite, mixing with glass frit, heating to a molten state at 915°C to form a sodalite glass matrix, and solidifying for long-term storage. Less long-term leaching is expected if the solidifying cooling rate does not cause cracking. In addition to thermal stress, this paper proposes a mathematical model for the stress formed during solidification, which is very large for fast cooling rates during solidification and can cause severe cracking. A solidifying glass or ceramic cylinder forms a dome on the cylinder top end. The temperature distribution during solidification causes the solidification stress and the dome resulting in an axial length deficit. The axial stress, determined by the length deficit, remains when the solid is at room temperature with the outer region in compression and the inner region in tension. Large tensions will cause cracking of the specimen. The temperature deficit, derived by dividing the length deficit by the coefficient of thermal expansion, allows solidification stress theory to be extended to the circumferential stress. This paper derives the solidification stress model, gives examples, explains how to induce beneficial stresses, and compares theory to experimental data.

Placental transfer of radioactive salts in the pregnant rabbit

The risks of radionuclidic contamination due to the easy transfer of water-soluble ions from the circulation of the pregnant woman to her fetus, encouraged us to study whether the ease of penetration of such ions is size-dependent. Three radiochemicals--22NaCl, 99mTcO4Na and 201TlCl were injected i.v. into pregnant rabbits on the 16th day of their pregnancy, and the rabbits were killed 15, 30, 60 or 120 min later. From each rabbit the blood, heart, kidney, liver and muscle were sampled and counted as well as placenta, amniotic fluid and some fetuses. At 15 and 60 min hearts and livers were excised from selected fetuses and blood clearance, organ-to-muscle and fetus-to-placenta ratios were calculated. The results indicate that the transplacental transfer of the small radionuclide 22Na+ is faster than that of 99mTcO4- and 201Tl+, reaching equilibrium about 3 h after its injection to the pregnant rabbit. 201Tl+ demonstrated a high localization in the pregnant rabbits' and fetuses' heart and kidneys, with a similar myocardial retention in both groups. Due to the concentration of 201Tl+, in spite of its large diameter, into the fetuses' heart muscle, careful consideration should be taken when injecting 201TlCl into pregnant women for myocardial imaging.

Systematic effects due to increasing self-absorption in activity standardization using 4πβ (PC)-γ coincidence counting

Effects of inhomogeneities in thin 4πβ counting sources on the results of activity standardizations were investigated using 59Fe and 134Cs. The inhomogeneities were due to non-uniformities in the sizes of the crystallines of the radioactive salts composing the source deposits. The measurements were made with a new type of proportional counter permitting 4πβ (PC)-γ measurements of up to five sources simultaneously. The sources formed by the crystallines with non-uniform distribution in size tended to yield results deviating from a linear fit even at relatively high β counting efficiencies. Efficiency extrapolation based on coincidence counting results is at present the most accurate method for activity standardizations whenever this method is applicable. The present investigation could lead to further improvements.

Adsorption of Bile Salts by the Cestodes, Hymenolepis diminuta and H. microstoma

The accumulation of purified sodium taurocholate (NaTC) and sodium glycocholate (NaGC) by Hymenolepis diminuta and Hymenolepis microstoma (Cestoda: Cyclophyllidea) was determined using radioactive bile salts. H. diminuta reached equilibrium levels of approximately 120 nmoles NaTC/g dry wt and 300 nmoles NaGC/g dry wt. Presentation of the bile salts in mixed micelles with 0.35 mM oleic acid did not alter these values. With H. microstoma, the maxima were 195 nmoles NaTC/g dry wt and 614 nmoles NaCG/g dry wt. These values were similarly unaffected by the addition of 0.35 mM oleic acid to the micelles. Equilibrium values of this magnitude, in media containing as much as 25 or 30 mM bile salt, and the maintenance of this level during incubations of 15 to 60 min eliminated the possibility that the accumulation was by diffusion or by any form of mediated transport into the worm. The accumulation on NaTC by H. diminuta was [Na+] independent, and insensitive to ouabain, DNP, and high [K+]. These observations, the maintenance of different levels of NaTC and NaGC, and the failure of the 2 bile salts to compete indicated that there was no active excretion mechanism operating in a fashion similar to the active transport of bile salts in the vertebrate small intestine. It was concluded that the accumulation of NaTC by H. diminuta was actually adsorption to the tegument. Comparable, although more limited, experiments extended this conclusion to the accumulation of NaGC by H. diminuta and of NaTC and NaGC by H. microstoma. It is suggested that bile salt monomers, rather than intact micelles, adsorb to specific loci on the tegument.

Transport of radioactive materials by jackrabbits on the Hanford reservation.

A survey was conducted near waste disposal trenches (B-C Cribs), Hanford Reservation, south-central Washington, to learn the extent to which jackrabbits (Lepus californicus) and their predators had dispersed radioactive salts, and to relate these data with parameters, such as topography, wind direction, vegetation types, and animal behavior, that might help explain the pattern of dispersal. Animals had access to the radionuclides for an unknown duration between 1958 and 1964. In 1972–1973, 6671 circular sampling sites (1.4 m2) were surveyed in the vicinity of the B-C Cribs. Radioactive feces, urine, soil, and vegetation were distributed in all directions from the cribs, but the area to the south and southwest was more densely and uniformly contaminated. Of the ultimate sampling units surveyed in 1972, 278 or 10.6% had count rates in excess of 10,000 counts/min measured with a Geiger-Mueller counter (background count rates were less than 500 counts/min). Of these 278 circular areas, 179 or 64% were found within 0.5 km of the cribs, 23.4% were between 0.5 and 1.0 km, and the remaining 12.2% were farther away. Most feces with a count rate greater than 20,000 counts/min was found within 400 m of the cribs, but jackrabbit pellets with count rates in excess of 100,000 counts/min were found up to 1.6 km from the cribs. Assuming a circular dispersal pattern we estimated that radioactive jackrabbit pellets were distributed over 15 km2. Surveys were conducted over 3000 ha and up to 20 km from the cribs to determine whether predators of jackrabbits were also involved in spreading radioactivity. Only four sources of radioactivity associated with predator activities were found (coyote feces; three collections of bone fragments under hawk feeding stations) up to 9.7 km from the cribs. All radioactivity found during this study was well within the boundaries of the Hanford Reservation. The results show how abundant native animals can effectively transport radioactive wastes. The potential for similar occurrences on nuclear installations should be evaluated so that appropriate measures can be taken to minimize the spread of contamination.

The Fate of Labelled Bile Salts Introduced into the Colon

Morris, J. S. & Heaton, K. W. The fate of labelled bile salts introduced into the colon. Scand. J. Gastroent. 1974, 9, 33–39.In 9 subjects undergoing T-tube drainage of bile, radioactive bile salts...

Ensemble pour la mesure instantanée du débit en conduite au moyen de radio-éléments

This equipment features a radio-nuclide (barium 137) generator directly connected to a pneumatic injector, and two similar detectors on the outside of the pipe connected to an electronic counter giving a direct reading of the values from which the rate of flow is derived. In developing these measurement methods, use was made mainly of such medium-period radio-nuclides as iodine 131, bromine 82 and sodium 24, With the following main purposes in view : (i) To find applications for short pipes (i.e. up to 80 diameters) ; (ii) Experimental confirmation of mathematical approaches ; (iii) Design and development of equipment for simple use. A barium 137 generator was developed, which has added considerable interest to the measurement of pipe flows by of radio-active salts. It relies on the natural caesium → barium 137 relationship, with the parent caesium 137 being fixed to a highly-selective ion- exchange resin. Washing this resin in water carries the barium 137 bred by the disintegrating caesium away, but without moving the latter. As barium 137 has a period of about 2.5 minutes, much higher radio-activity can now be fed into the pipe, for 100 minutes later finds it reduced to only 2-40 times its original value. This even makes repetitive closed-circuit tests feasible. In view of these promising results, the author's team developed an injector fitting the generator jointly with Societe Saint-Gobain-Techniques Nouvelles-who had supplied the generator-in order to climinate any need to manipulate the radioactive solution between preparing it and feeding it into the pipe. A brief description of the method now follows, in order to seriate the principal questions considered in the study : In order to determine the rate of flow in a pipe at least 50 diameters long and whose cross-sections are known, a radio-active solution is injected and its times of passing two specific cross-sections A and 13 are detected from outside the pipe. The most important points considered in describing the method are the following : (i) Injection ; (ii) Distance of point of from first detection section ; (iii) Distance between the two detection sections ; (iv) Detection. The mathematical approaches are specifically dealt with in a three-part Appendix, as follows: The tirst part shows that, knowing the abscissa of the temporal centre of gravity of the curve corresponding to the passage of the radio-active solution, the rate of flow in the pipe can be asceriained by outside observation. The second part discusses deformation due to the detector filters. The third part leads to the estimation of discharge mor where interpretation is based on one particular geometrical point only. The heading injection ((i) above) covers the injector and its operation. Heading (ii) refers to a study of turbulent diffusion phenomena and the efficient mixing length where detection is outside the pipe, and especially the determination of I∞ from observed I2 and I2 values. The distance between detection sections (heading (iii)) does not enter into the method error calculations. It determines the accuracy of radio-active solution passage time measurement at the two sections. Heading (iv) comprises the analysis of the two following data abstraction methods : (a) Plotting of curves and determination of a point with about the same characteristics as the centre of gravity as regards measurement. (b) Bringing the centre of gravity of the radio-active cloud into evidence by direct processing of observed data. The discussion of (a) shows the difficulties of using a single geometrical point and defines one of them, and Table 1 lists the results obtained from 110 injections in successive groups of 10. Under (b), the calculator associated with the detectors is described, sub-groups are listed, and the development tests involved are reviewed. Finally, the advantages, applications and potential development scope of the method are discussed.

Regulation of Cholesterol Catabolism by Bile Salts and Glycyrrhetic Acid in vivo.

SummaryTritiated cholesterol was injected intraperitoneally into rats having 2 bile-duct cannulae, one for bile collection and the other for intraduodenal infusion of bile-salt solutions. Intraduodenal infusion of taurocholate (10 mg/hr) had no effect on rates of radioactive bile-salt formation from cholesterol-H3. Intraduodenal infusion of taurochenodeoxycholate (10 mg/hr) inhibited radioactive bile salt formation. Taurocholate infusion also resulted in a 6-fold increased secretion of a dihydroxycholanate, apparently taurochenodeoxycholate. Sodium β-glycyr-rhetate infusion (125 μg/hr) had no significant effect on secretion of either radioactive cholesterol or radioactive bile salts.

Field Study of the Mobility of Oribatei (Acari), Using Radioactive Tagging

To some extent, it is possible to check the validity of these hypotheses by following the movements of individuals in the field. Taking into account 'the size of the animals, the only practicable method for this purpose is by radioactive tagging. After labelling, the animals are returned to the field and their daily movements are observed with a Geiger counter. Two methods were used to label the animals. The first, proposed by Davis & Nagel (1956) consists of immersing the individuals in a radioactive solution, by ion exchange, some radioactive salts remain on the cuticle. The animals were immersed three to six times for 1 min every 2 h in a solution of Na2Ir192Cl6 (2 mc/ml) or of Sc46Cl (8 mc/ml). One day after the last immersion, the animals were washed in distilled water, to remove any salt not fully bound on the cuticle. Generally, forty animals were treated simultaneously and at the end of the labelling, twenty were selected whose radioactive level was adequate for detection in the field. Unfortunately, this simple method does not suit many Oribatids, most of which have an unwettable cuticle. For such animals, I used a different method consisting of mixing a small amount (250 nrc) of Ce144Cl in a little Students' oil Colour, and putting a tiny drop of this paint on the hysterosoma. Cerium-144 is an isotope with quite a long half-life, and gives by disintegration a daughter isotope, Praseodymium-144, which is a very strong beta emitter. Thus, the detection of the animals is easy with a Geiger-Muller tube (laboratory portable monitor M.B.L.E., PN 282/A equipped with a Geiger tube, ASDAM 18505). The amount of radioactive material that was used for these experiments was 10 mc of iridium, 40 mc of scandium and twice 5 mc of cerium. The radioactivity of these solutions was sufficiently high to require the precautions usually associated with a properly equipped radioisotope laboratory (lead bricks, laboratory monitor, pocket dose-meter .) and a special training of the experimenter.

Carcinoidosis and the effect of serotonin on the gastrointestinal tract.

Carcinoid tumors secrete serotonin, which increases intestinal and gastric motility and tone, as well as the secretion of mucus from the stomach. The syndrome of functioning carcinoid tumors is produced by the presence of excessive amounts of serotonin in the blood. Not all the clinical features need be present for diagnosis. Demonstration of abnormal amounts of 5-hydroxy-3-indole acetic acid in the urine confirms the diagnosis. The amounts of this substance vary from time to time, and more than one determination may be needed to make the diagnosis. Postoperative urinary measurements of this chemical are valuable as a guide to the development of metastatic tumors. The treatment of choice is surgical removal of as much tumor tissue as possible. Irradiation and the administration of radioactive salts are of doubtful value. The use of serotonin “antagonists” has yielded disappointing results. Chlorpromazine and symptomatic measures for the relief of diarrhea, pain, and asthma are indicated.

Radioactive Contamination of Polyethylene Surfaces by Cs-137 in Solution and Their Decontamination

The radioactive contamination of polyethylene surfaces by Cs/sup 137/ in solution- and their subsequent decontamination were investigated. The time and temperature of immersion, concentration of cesium and other ions in solution, concentration of cesium and other ions in solution, and pretreatment of the sample were varied to study the effects of these factors. Addition of non- radioactive salts, such as CsNO/sub 3/ and NH/sub 4/NO/sub 3/, to a carrier-free Cs/sup 137/NO/sub solution, and increase in temperature decrease the radioactive contamination, whereas pretreatments of polyethylene surfaces have little effect on the contamination. Autoradiographs of the contaminated surfaces always showed a pronounced nonuniformity of distribution of the activity, i.e., numerous localized spots of Cs/sup 137/, on the surface. When the contaminated samples were immersed in water, it was found that the resulting decontamination curves consist of the fast and slow desorption steps. Hot nitric acid (1: 4) was found to be most effective for decontamination among the reagents tested. Physical adsorption of cesium ions on polyethylene surfaces seems to be the predominant phenomenon under normal laboratory conditions.

Radioactive Labelling of Membrane Filters for the Assay of Air-borne Material

The application of special features of membrane filters in the assay of air-borne material by radioactive thickness gaging is discussed. The filters themselves were converted into the radiation source used, thereby eliminating the effect of filter thickness from measurement. Initial work was performed by adsorbing radioactive nickel or thallium salts from solution upon the filter surface. (M.C.G.)

Enamel Penetration by Radioactive Salts of Zinc, Calcium, Silver, Plutonium, Palladium and Copper

Enamel Penetration by Radioactive Salts of Zinc, Calcium, Silver, Plutonium, Palladium and Copper

Emanating power and the age of complex silica gels.

PARCHOMENKO1 demonstrated that, when mixing silica gels with electrolytes of some metals such as magnesium, manganese, cobalt and nickel (with iron always present) by precipitating their chlorides with sodium silicate, compounds can be prepared which are highly absorbent for radioactive salts, and owing to their large colloidal surface give off radon nearly quantitatively.

Introduction of Sodium Iodide into the Calcified Dental Tissues

This report deals with one aspect of tooth permeability, namely, the introduction of a foreign substance into the calcified dental tissues. Primarily its purpose is the development of a new method for studying this phenomenon, utilizing sodium iodide as the foreign substance. Investigation in tooth permeability, especially with regard to enamel, has considered two aspects of the problem-penetration from the pulp outward to the external surface, and from without, inward. The methods employed in these studies included: Various staining solutions applied to the whole tooth in vitro (1), (2). Complex dyes inserted into the pulp and applied to the enamel surface in vivo (3), (4). Introduction of radioactive salts in vitro and in vivo (6, 7, 8, 9, 10). These procedures have provided considerable data on the subject, but are nevertheless open to criticisms. Results published on the basis of experimentation with extracted teeth can be considered only an indication of the true picture because loss of vitality has been shown to influence permeability (3). Investigators using dyes in direct contact with the teeth, for the most part, have employed complex molecular dyes. Since permeability depends largely on the size and charge of the molecule, results obtained from the use of these dyes cannot be applied to calcium, phosphorous, fluorine, and other small inorganic ions which bathe the teeth in vivo. Neither the use of extracted teeth nor dyes contacting the teeth can be correlated with normal physiological conditions. The use of radioactive isotopes, while an excellent method of investigation, requires extensive equipment, is a difficult procedure, and does not clearly demonstrate the distribution of the introduced substance. It has nevertheless contributed much information concerning the degree of tooth permeability in vivo. Wasserman and Blayney (5, 6), Volker and Sognnaes (7, 10), and Barnum and Armstrong (9) have demonstrated that radioactive phosphorous injected intraperitoneally or intravenously finds its way into the dentin and enamel of the teeth. The dentin, as might be expected, takes up considerably more phosphorous than the enamel. All investigators agree that the phosphorous which finds its way into the dentin does so through the blood. As far as the enamel is

THE USE OF RADIOACTIVE PHOSPHORUS IN TRANSLOCATION STUDIES

THE USE OF RADIOACTIVE PHOSPHORUS IN TRANSLOCATION STUDIES