Radioactivity Levels Research Articles

Toward Stability Enhancement of NTS1R-Targeted Radioligands: Structural Interventions on [99mTc]Tc-DT1.

The neurotensin subtype 1 receptor (NTS1R) is overexpressed in a number of human tumors, thereby representing a valid target for cancer theranostics with radiolabeled neurotensin (NT) analogs like [99mTc]Tc-DT1 (DT1, N4-Gly7-NT(8-13)). Thus far, the fast degradation of intravenously injected NT-radioligands by neprilysin (NEP) and angiotensin-converting enzyme (ACE) has compromised their clinical applicability. Aiming at metabolic stability enhancements, we herein introduce (i) DT7 ([DAsn14]DT1) and (ii) DT8 ([β-Homoleucine13]DT1), modified at the C-terminus, along with (iii) DT9 ([(palmitoyl)Lys7]DT1), carrying an albumin-binding domain (ABD) at Lys7. The biological profiles of the new [99mTc]Tc-radioligands were compared with [99mTc]Tc-DT1, using NTS1R-expressing AsPC-1 cells and mice models without or during NEP/ACE inhibition. The radioligands showed enhanced in vivo stability vs. [99mTc]Tc-DT1, with [99mTc]Tc-DT9 displaying full resistance to both peptidases. Furthermore, [99mTc]Tc-DT9 achieved the highest cell internalization and tumor uptake even without NEP/ACE-inhibition but with unfavorably high background radioactivity levels. Hence, unlike C-terminal modification, the introduction of a pendant ABD group in the linker turned out to be the most promising strategy toward metabolic stability, cell uptake, and tumor accumulation of [99mTc]Tc-DT1 mimics. To improve the observed suboptimal pharmacokinetics of [99mTc]Tc-DT9, the replacement of palmitoyl on Lys7 by other ABD groups is currently being pursued.

Investigation on the radioactivity levels of seawater, sediments, and biota in Daya Bay, China

ObjectiveTo investigate the radioactivity levels of seawater, sediments, and biota in the Daya Bay sea area, China, in order to establish the radioactivity baseline values, and provide basic data for the assessment of potential radiological risks that might result from the application of nuclear technology or human activities. MethodsSamples of seawater, sediments, and biota were collected from the Daya Bay sea area and analyzed. Their radioactivity baseline data were then compared with information from other regions in China and around the world reported in related literature. ResultsFor the seawater samples, the activity concentrations of natural radionuclide 40K were 9.9–10.4 Bq/L, while 238U, 226Ra, 210Pb, 137Cs, and 110Agm were below the minimum detectable activity (MDA). Regarding the sediment samples, the activity concentrations of 238U, 228Ra, 226Ra, 210Pb, 40K, and 137Cs were 38.1–40.4, 49.1−53.7, 32.6−38.6, 59−95, 590−650, and 0.48–0.88 Bq/(kg dry weight), respectively, while 110Agm was below the MDA. For the marine shrimps in the biota samples, the activity concentrations of 228Ra, 226Ra, 40K, and 137Cs were 1.14–2.75, 0.17−0.43, 63–76, and 0.038–0.045 Bq/(kg wet weight), respectively, while 238U, 210Pb, and 110Agm were all below the MDA. Furthermore, for the marine fishes in the biota samples, the activity concentrations of 228Ra, 226Ra, 210Pb, 40K, and 137Cs were 2.1–19.7, 0.32–3.78, <2.2–2.8, 59–70, and <0.007–0.026 Bq/(kg wet weight), respectively, while 238U and 110Agm were all below the MDA. 228Ra was found to be concentrated in Osteomugil ophuyseni with 19.7 Bq/(kg wet weight). ConclusionsThe radioactivity levels of seawater and marine sediments in the Daya Bay sea area are within the range of the normal background values. Osteomugil ophuyseni exhibited higher concentrations of 228Ra than other species in this study, while the other species in the biota show no significant difference in the radioactivity levels from data in relevant literature.

Radiation and Environmental Safety in the Exploration and Development of Metal Deposits in South Yakutia

Radiometric surveys of mining dumps on spent placers of gold, monazite and the exploited gold-uranium ore deposit in South Yakutia were carried out. It is established that the dumps of alluvial, overburden and waste rocks in terms of the effective specific activity of radionuclides when used in construction work are characterized by different degrees of tolerance. It is shown that stacked radioactive ore dumps at the “Lunnoye” deposit after heap leaching of gold become powerful uncontrolled sources of radioactive pollution of the environment. It is recommended to conduct periodic monitoring of their radioactivity levels by express methods of field radiometry for the safe use of mining dumps as building materials.

Assessment of natural radioactivity levels in soil samples from Dejen district, Ethiopia.

Gamma ray spectrometry was used to determine the activity concentrations of naturally occurring radionuclides in 12 soil samples collected at random from Dejen district, Ethiopia. In agricultural soils, the calculated mean activity concentrations of 226Ra, 232Th and 40K were 33.44 ± 2.01, 66.02 ± 4.54 and 214.16 ± 8.90 Bq kg-1, respectively, and in virgin soils, they were 38.05 ± 2.48, 61.78 ± 4.76 and 240.32 ± 10.79 Bq kg-1, respectively. The findings were discussed and compared to other studies' findings. The mean values of absorbed dose rate, annual effective dose rate and radium equivalent activity in agricultural land soils are 67.24 nGyh-1, 0.083 mSvy-1 and 144.57 Bq kg-1, and in virgin land soils are 67.53 nGyh-1, 0.082 mSvy-1 and 144.90 Bq kg-1, respectively. These findings were discussed and compared to the internationally recommended value. As a result, it is possible to conclude that the soil samples are safe for residents and those involved in agricultural activities.

A Review of Experiments Reporting Non-Conventional Phenomena in Nuclear Matter Aiming at Identifying Common Features in View of Possible Interpretation

The purpose of the present paper is to clarify, as far as it is possible, the overall picture of experimental results in the field of non-conventional phenomena in nuclear matter published in the scientific literature, accumulated in the past few decades and still missing a widely accepted interpretation. Completeness of the collection of the experiments is not among the aims of the effort; the focus is on adopting a more comprehensive and integral approach through the analysis of the different experimental layouts and different results, searching for common features and analogous factual outcomes in order to obtain a consistent reading of many experimental evidences that appear, so far, to lack a classification in a logic catalogue, which might be compared to a building rather than a collection of single stones. Particular attention is put on the issue of reproducibility of experiments and on the reasons why such a limitation is a frequent characteristic of many experimental activities reported in published papers. This approach is innovative as compared with those already available in the scientific literature. In a synoptical table, a comprehensive classification is given of the twenty experiments examined in terms of types of evidences that are ascertained by the experimenters in their published papers but are “unexpected” according to well-established physical theories. Examples of such unexpected evidences (named also non-conventional or weird) evidences are: excess heat generation, isotope production, reduction of radioactivity levels, and production of neutrons or alpha particles. These evidences are classified taking into account both the material where the evidence takes place (solutions, metals, rocks and artificial materials) and the stimulation techniques (supply of electric voltage, irradiation by photons, mechanical pressure) used to generate the evidences (which do not appear in the absence of such stimuli at an appropriate intensity). Also, in our paper, “identity cards” are provided for each experiment examined, including details that emerged during the experiment and were reported in each respective paper, that sometimes are not given adequate consideration either by the author of the experiment or in other review papers. The analysis of the details provides suggestions (also referred to as clues in this papers) used to formulate the content of the second part of each identity card, where inferences deduced from facts are outlined in view of presenting tentative interpretation at the microscopic level. This is done by concentrating attention on the clues repeated in different experiments in order to yield possible explanations of the “unexpected” evidences. The main outcome of such analysis is that, in all examined cases, a common “operation” can be identified: the stimulation techniques mentioned above can be interpreted as a sort of compression producing a ramp of energy densification (with reference to volumes in space or time coordinates). Here we use the term “compression” to indicate an operation activated by the experimenter; as such, it is objective. We consider energy densification an inference of possible consequences of the operation on the status of the system. Five types of densifications were identified. This reading in terms of energy densification is in accordance with the predictions of the Deformed Space Time theory, reported in the scientific literature, in the context of a generalization of the Einstein relativity theory, according to which the existence of energy thresholds is found to separate, for each interaction, the flat metric part from the deformed metric part and the appearance of new microscopic effects as a consequence of trespassing such thresholds. The phenomena occurring in the deformed part of the interaction metric are governed by the energy density in the space-time (volume and time interval). This energy density is computed from the threshold energies and is peculiar to the phenomenology under consideration. As a conclusion, it is suggested that the revealed qualified information, homogenized and elaborated on, might help in repeating, with proper adjustments and adequate additional instrumentation, some key experiments, in order to ensure systematic reproducibility, which is a prerequisite for interpretations and explanations to be sound and credible, as well in deriving from such an effort, indications for new experiments. It is uncomfortable that, after thirty years, there are still pending questions to which the most acknowledged physical theories are not capable of giving an answer. Even a definitive demonstration that all these experiments have decisive faults would be preferable than leaving the issue unaddressed. Major research agencies, for instance in the USA and in Europe, are moving in this direction.

Th-232 Radiological Aspects of Carbonate Niobium Mining Waste Use as Agricultural Amendment

The use of mining residues in agriculture may be possible, as long as there be previous studies in different areas, one of them being the analysis of the involved radionuclides behavior. This study determined the concentrations of 232Th activity in soil, soil treated with lime, soil with carbonate residue from niobium mining, soil with the mixture of lime and carbonate, in two moments. The transfer factor of 232Th from the soil to the plant was analyzed, in this case, lettuce (n=20), in the different types of treatment and in two moments. The addition of carbonate to the soils did not significantly alter the levels of radioactivity for 232Th radionuclide in lettuce. The effective dose resulting from the lettuce ingestion varied from 0.09 to 0.3 µSv y-1.

Natural radioactivity and radiological hazard analysis of construction stones from various quarries in Machakos County-Kenya.

The radioactivity levels of rocks sampled from the quarries of Kyasioni, Mavoloni and Kathaana located in the lower Eastern County of Machakos in Kenya were determined. Forty-two samples were collected using stratified random sampling and analysed using NaI(TI) detector with a specially designed lead shield. The parametric values of activity concentration, absorbed dose, annual dose rate and hazard indices were estimated using activity-dose relations suggested in UNSCEAR and ICRP reports. The mean activity concentration for the entire work for 238U (226Ra), 232Th and 40K were 68.33±3.11, 101.10±1.83 and 1084.02±30.28Bq/kg, respectively. Kyasioni quarry presented the highest activity concentration of 74.75±3.15, 118.48±1.91 and 1120.35±30.07Bq/kg for 226Ra, 232Th and 40K, respectively. The average annual effective dose was estimated as 0.58±0.01, 0.47±0.01 and 0.52±0.01mSv/y for Kyasioni, Kathaana and Mavoloni quarries, respectively. Other radiological parameters estimated from the corresponding activities were within the recommended limits hence guaranteeing safety to the users.

A Radiological Risk Assessment of 226Ra, 228Ra and 40K Isotopes in Tilapia Fish and its Granitic Environment in Singida Municipality, Tanzania

Consumption of fish containing elevated levels of radionuclides can lead to undesirable health effects for consumers. People in the Singida Municipality harvest fish from lakes and ponds of granite rocks which are linked with hazardous radioisotopes that may be bio-concentrated by fishes they consume. Currently, no study has ascertained the levels of radioisotopes in fish from these environments. This study was carried out to analyse the radioactivity levels of 226Ra, 228Ra and 40K isotopes in order to assess the radiological risk associated with Tilapia fish consumption and its environment in Singida Municipality. Some 51 samples, which included water (20), sediment (20), Nile tilapia (8) and Manyara tilapia (3), were randomly sampled and composited; then, they were analysed using a high-purity germanium (HPGe) detector, between May and June 2022. The results revealed that (i) the activity levels of 228Ra were below the detection limit for fish and water samples, while in sediment, the combined activity of 228Ra was within the acceptable international levels; (ii) the mean activity concentrations of 226Ra and 40K in all other samples were within the recommended levels; (iii) the activities of radionuclides in the samples analysed were high in sediments, followed by fish, and lastly water; (iv) the bioaccumulation results show that only 40K was bio-accumulated (with 1.26 in Nile tilapia), while other radionuclides (226Ra, 228Ra) were not bio-accumulated; (vi) the radionuclide transfer from water to fish was higher compared to the radionuclide transfer from sediment to fish; (vii) the human effective doses due to consumption of Nile tilapia and Manyara tilapia were 0.00973 and 0.005 mSv/y, respectively, which is below the 1 mSv/y international limit. These findings therefore show that the current levels of radioactivity in fish in the study area do not pose a significant radiological risk to fish consumers. However, more studies on other types of fish are recommended.

Demonstration of indirectly driven implosion experiments with cryogenic pure deuterium layered capsules on the Shenguang Laser Facility

Abstract To achieve ignition in a laboratory via inertial confinement fusion, a spherical capsule containing a frozen layer of deuterium and tritium (DT) fuel will be imploded on an MJ-class laser facility. However, if pure deuterium fuel can be used in place of DT fuel for tuning shots, we may speed up the process of ignition experiments while maintaining the surrogacy by significantly reducing the level of radioactivity. Unfortunately, it has long been assumed that neither the approach of symmetrical infrared irradiation used in the Omega direct-drive experiments nor the method of beta-layering used in the NIF experiments can be used to smooth the D layered capsule in cylindrical hohlraums. The difficulty in smoothing the D ice layer prevents us from taking advantage of cryogenic D-layered capsules in indirect-drive experiments. In this work, we established a procedure to form a uniform D-ice layer for capsules held in cylindrical hohlraums and carried out indirect-drive cryogenic D-layered implosion experiments using a squared laser pulse on the Shenguang Laser Facility in China. The quality of the D ice layer is characterized by phase-contrast imaging. The root-mean-square of the power spectrum in modes 2–100 is about 2.2 μm. The implosion performance of the D-layered capsules is close to the prediction of one-dimensional simulations. The measured neutron yield and areal fuel density are 1.2 × 1011 and 80 mg cm−2, respectively.

Influence of atmospheric circulation and local parameters on activity concentration of gross alpha and gross beta in Granada, Spain

This work analyses the influence of local meteorology and air mass origin on radioactivity levels measured in Granada (Southern Spain). To the scope, gross α and gross β activities at ground-level air were weekly recorded from 2006 to 2021, by collecting aerosol filters and successively analysing them by low-level proportional counting. Time series decomposition shows a strong correlation between the seasonal components of gross α and gross β and the local meteorological parameters, in particular temperature and wind speed. Back trajectories reaching the study area during the sampling, calculated at three height levels (750 m, 1500 m, and 3000 m a.s.l.), were analysed by three methods with the aim to determine the main characteristics of air masses reaching Granada, and their impact on airborne radioactivity levels. The results of the residence time and clustering analyses showed that an increase in the radioactivity levels in the southeast of Spain is connected with air masses coming from the Mediterranean at 750 m and from the South (Sahara Desert) at 3000 m. In line with the outcomes obtained by the cluster analysis, the Concentration Weighted Trajectory (WCWT) results highlight that the air masses transported from Mediterranean and African regions are a potential source of gross α and gross β. Moreover, the findings of the WCWT bring a new aspect by revealing that the southern France region can also have a significant contribution to gross alpha and beta activities.

Synthesis of Sulfur-35-Labeled Trisulfides and GYY-4137 as Donors of Radioactive Hydrogen Sulfide.

Hydrogen sulfide has emerged as a key gasotransmitter in humans and in plants, and the addition of exogenous hydrogen sulfide has many beneficial effects in vivo and in vitro. A challenge in investigating the effect of exogenous hydrogen sulfide is tracking the location of exogenous hydrogen sulfide on an organism and cellular level. In this article, we report the synthesis of three key chemicals (cysteine trisulfide, glutathione trisulfide, and GYY-4137) that release radiolabeled 35S as hydrogen sulfide. The synthesis started with the reduction of Na235SO4 mixed with Na2SO4 to generate hydrogen sulfide gas that was trapped with aq NaOH to yield radiolabeled Na2S. The Na2S was converted in one step to GYY-4137 at 65% yield. It was also converted to bis(tributyltin) sulfide that readily reacted with N-bromophthalimide to yield a monosulfur transfer reagent. Trisulfides were synthesized by reaction with the monosulfur transfer reagent and the corresponding thiols. The levels of radioactivity of the final products could be varied on a per gram basis to alter the radioactivity for applications that require different loadings of hydrogen sulfide donors.

Automated radiosynthesis and in vivo evaluation of 18F-labeled analog of the photosensitizer ADPM06 for planning photodynamic therapy

BackgroundA family of BF2-chelated tetraaryl-azadipyrromethenes was developed as non-porphyrin photosensitizers for photodynamic therapy. Among the developed photosensitizers, ADPM06 exhibited excellent photochemical and photophysical properties. Molecular imaging is a useful tool for photodynamic therapy planning and monitoring. Radiolabeled photosensitizers can efficiently address photosensitizer biodistribution, providing helpful information for photodynamic therapy planning. To evaluate the biodistribution of ADPM06 and predict its pharmacokinetics on photodynamic therapy with light irradiation immediately after administration, we synthesized [18F]ADPM06 and evaluated its in vivo properties.Results[18F]ADPM06 was automatically synthesized by Lewis acid-assisted isotopic 18F-19F exchange using ADPM06 and tin (IV) chloride at room temperature for 10 min. Radiolabeling was carried out using 0.4 μmol of ADPM06 and 200 μmol of tin (IV) chloride. The radiosynthesis time was approximately 60 min, and the radiochemical purity was > 95% at the end of the synthesis. The decay-corrected radiochemical yield from [18F]F− at the start of synthesis was 13 ± 2.7% (n = 5). In the biodistribution study of male ddY mice, radioactivity levels in the heart, lungs, liver, pancreas, spleen, kidney, small intestine, muscle, and brain gradually decreased over 120 min after the initial uptake. The mean radioactivity level in the thighbone was the highest among all organs investigated and increased for 120 min after injection. Upon co-injection with ADPM06, the radioactivity levels in the blood and brain significantly increased, whereas those in the heart, lung, liver, pancreas, kidney, small intestine, muscle, and thighbone of male ddY mice were not affected. In the metabolite analysis of the plasma at 30 min post-injection in female BALB/c-nu/nu mice, the percentage of radioactivity corresponding to [18F]ADPM06 was 76.3 ± 1.6% (n = 3). In a positron emission tomography study using MDA-MB-231-HTB-26 tumor-bearing mice (female BALB/c-nu/nu), radioactivity accumulated in the bone at a relatively high level and in the tumor at a moderate level for 60 min after injection.ConclusionsWe synthesized [18F]ADPM06 using an automated 18F-labeling synthesizer and evaluated the initial uptake and pharmacokinetics of ADPM06 using biodistribution of [18F]ADPM06 in mice to guide photodynamic therapy with light irradiation.

Evaluation of radioactivity levels and radiological hazards of some endemic plants used as medicine in Ankara, Turkey

In this study, natural radioactivity levels (226Ra, 232Th, and 4 K) of some medicinal plant samples with known anti-oxidative properties, which are frequently consumed by animals and humans, were obtained from Ankara province and its surroundings (Mamak, Kızılcahamam, Beypazarı, Kahramankazan, and Polatlı districts) were determined using a thallium-doped sodium iodide NaI(Tl) gamma spectrometry. By using the determined natural radioactivity concentrations in the collected plant samples, the number of radiological doses that people could be exposed by consuming these plants was calculated. As a result of the study, 226Ra, 232Th, and 4 K radioactivity concentration ranges of the plant samples were found be 14.69 ± 1.27–59.08 ± 3.12 Bq kg−1, 1.78 ± 0.04–50.05 ± 2.76 Bq kg−1 and 207.24 ± 34.09–826.13 ± 25.40 Bq kg−1, respectively. The highest 226Ra, 232Th, and 4 K activity concentrations were measured in Astragalus densifolius subsp. ayashensis (Kahramankazan), Astragalus kochakii (Kahramankazan) and Rumex patientia (Patience Dock) (Kahramankazan) plants, respectively. The lowest 226Ra, 232Th and,4 K activity concentration plants were determined respectively as Rumex patientia (Mamak), Lavandula angustifolia (Kızılcahamam), and Astragalus acikirensis (Polatlı). The establishment and routine repetition of environmental radioactivity monitoring programs in each region are important for human and animal health, and the results of this study gain importance for Ankara and its surroundings in terms of environmental health.

Generation of rf radiation by low-intensity laser pulse trains in air.

In this paper, we analyze and numerically simulate mechanisms for generating directed rf radiation by a low-intensity laser pulse train (LPT) propagating in air. The LPT ionizes the air, forming a plasma filament. The ionization process relies on the background level of radioactivity which plays an important role in initiating a collisional ionization process. In our model a low-intensity LPT photoionizes background negative ions (produced by ambient ionizing radiation) and provides the seed electrons necessary to initiate collisional ionization. The intensity of the LPT is far below tunneling ionization levels. The ponderomotive forces associated with the LPT and self-fields drive plasma oscillations predominately in the radial direction. The driven radial electron currents in turn generate directed rf radiation. As the plasma density builds up on axis, the later portion of the LPT can defocus and limit the interaction length. The spectrum of the rf radiation consists of the fundamental frequency associated with the pulse separation time as well as harmonics. The rf generation mechanism is analyzed using fluid equations which incorporate, among other things, the effects of background radioactivity, photoionization, collisional ionization, ponderomotive and space-charge effects, and electron attachment-recombination processes. As an example, for a specific set of parameters, the rf spectrum and intensity are compared to experimental data.

Uranium migration and radioactive characteristics of the Sarıçiçek and Sarıhan Granodiorites

The radionuclide concentrations of eU (ppm), eTh (ppm), K (%) and dose rate values were measured in Sarıçiçek (Gümüşhane) and Sarıhan (Bayburt) granodiorites for a duration of 5 minutes at each of 532 measurement points. The radioelement ratios (eU/eTh, eU/K, and eTh/K) indicating the origins of the rocks, the geochemical indicators (Ume, F parameter, and eU-(eTh/3,5) rate) showing the uranium mobility and the radioelement concentrations were calculated and mapped within the study areas. The average K, eU, and eTh concentrations were calculated as 2.98%, 3.15 ppm, and 12.45 ppm for Sarıçiçek granodiorite, and 1.83%, 2.73 ppm, and 13.6 ppm for Sarıhan granodiorite, respectively. Higher radioactivity values were observed in basaltic, sedimentary, and ultramafic rock combinations within the granodiorite masses. In the classification according to radioelement ratios, it was concluded that the rocks in the study areas formed as a mixture of upper mantle and crustal materials. In both study areas, there was uranium transport from the granodioritic masses into the surrounding rocks, and accordingly, the rocks in the surrounding formations were enriched in uranium. As a result, radioactivity levels, rock formation origins, and uranium transport of both granodioritic masses and rocks in the surrounding formations were determined by evaluation with radioelement concentration values and ratios and migration parameters. The study areas were characterized by associating them with geology in light of radioactive data.

The Glutaminase-1 Inhibitor [11C-carbony]BPTES: Synthesis and Positron Emission Tomography Study in Mice.

Bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES) is a selective inhibitor of glutaminase-1 (GLS1), consequently inhibiting glutaminolysis. BPTES is known for its potent antitumor activity and plays a significant role in senescent cell removal. In this study, we synthesized [11C-carbonyl]BPTES ([11C]BPTES) as a positron emission tomography (PET) probe for the first time and assessed its biodistribution in mice using PET. [11C]BPTES was synthesized by the reaction of an amine precursor () with [11C-carbonyl]phenylacetyl acid anhydride ([11C]2), which was prepared from [11C]CO2 and benzyl magnesium chloride, followed by in situ treatment with isobutyl chloroformate. The decay-corrected isolated radiochemical yield of [11C]BPTES was 9.5% (based on [11C]CO2) during a synthesis time of 40 min. A PET study with [11C]BPTES showed high uptake levels of radioactivity in the liver, kidney, and small intestine of mice.

Assessment of Radiological Hazards in Some Foods Products Consumed by the Malian Population Using Gamma Spectrometry

Background: Food consumption is one of the most important routes for radionuclide intake for the public; therefore, there is the need to have a comprehensive understanding of the amount of radioactivity in food products. Consumption of radionuclide-contaminated food could increase potential health risks associated with exposure to radiation such as cancers. The present study aims to determine radioactivity levels in some food products (milk, rice, sugar, and wheat flour) consumed in Mali and to evaluate the radiological effect on the public health from these radionuclides.Materials and Methods: The health impact due to ingestion of radionuclides from these foods was evaluated by the determination of activity concentration of radionuclides &lt;sup&gt;238&lt;/sup&gt;U, &lt;sup&gt;232&lt;/sup&gt;Th, &lt;sup&gt;40&lt;/sup&gt;K, and &lt;sup&gt;137&lt;/sup&gt;Cs using gamma spectrometry system with high-purity germanium detector and radiological hazards index in 16 samples collected in some markets, mall, and shops of Bamako-Mali.Results and Discussion: The average activity concentrations were 9.8±0.6 Bq/kg for &lt;sup&gt;238&lt;/sup&gt;U, 8.7± 0.5 Bq/kg for &lt;sup&gt;232&lt;/sup&gt;Th, 162.9±7.9 Bq/kg for &lt;sup&gt;40&lt;/sup&gt;K, and 0.0035±0.0005 Bq/kg for &lt;sup&gt;137&lt;/sup&gt;Cs. The mean values of radiological hazard parameters such as annual committed effective dose, internal hazard index, and risk assessment from this work were within the dose criteria limits given by international organizations (International Commission on Radiological Protection and United Nations Scientific Committee on the Effects of Atomic Radiation) and national standards.Conclusion: The results show low public exposure to radioactivity and associated radiological impact on public health. Nevertheless, this study stipulates vital data for future research and regulatory authorities in Mali

Effect of Grain Size on Radionuclide Content in Sediment Samples from Kolo Creek, Bayelsa State, Nigeria

The effect of grain sizes on radionuclide concentration in soil and sediment samples from Kolo creek, Bayelsa State was investigated using gamma spectroscopy. Eight (8) samples of sediment were collected around the oil spill site of the creek. All the samples were separated into four different grain sizes, A (0.5mm), B (1mm), C (1.5mm) and D (2mm), making a total of 32 sediment. The activity concentration in sediment samples of grain sizes 0.5 mm, 1.0mm, 1.5mm and 2mm were determined. In sediment samples of grain sizes 0.5mm(A), the activity concentration of 226Ra , 232Th and 40K ranges from 2.24 to 20.032.43Bq/kg, 3.21 to 5.591.32 Bq/kg and 24.46 4.06 to 795.99 6.20 Bq/kg respectively. For grain size of 1.0mm (B) the activity concentration of 226Ra, 232Th and 40K varies from 2.661.30 to 26.64Bq/kg, 2.19 0.95 to 33.47 Bq/kg and 43.38 to 739.21Bq/kg respectively. For grain size of 1.5mm (C) the activity concentration of 226Ra, 232Th and 40K varies from 4.401.09 to 33.93± 3.65 Bq/kg, 2.14±1.72 to 26.15±5.3 Bq/kg and 39.90±3.54 to 471.36±6.12 Bq/kg respectively. For grain size of 2.0 mm (D) the activity concentration of 226Ra, 232Th and 40K varies from 4.81±1.84 to 40.29±2.50 Bq/kg, 2.19±1.40 to 83.20±3.90 Bq/kg and 39.01 ±4.00 to 497.56±5.87Bq/kg respectively. The result obtained shows there was no clear trend in variation of activity concentration with grain sizes. The mean values obtained are below the world average of 35, 30 and 400 Bq/kg for 226 Ra, 232Th and 40K for grain sizes of 0.5, 1.0, 1.5 and 2.0 mm respectively in all the communities except samples from Kolo that recorded 471.36±6.12 to 795.99±6.44 Bq/kg in all the grain sizes. Radiological risk parameters such as Absorbed Dose Rate, Annual Effective Dose Equivalent, Annual Gonadal Dose Equivalent, Annual Utility Index, Radioactivity Level Index, Hazard Indices and Excess Life Cancer Risk were estimated and values were found to be within the word average. From this study, the sediment of the given grain sizes will pose no radiological health risk if used in farming and in building construction.

GROSS ALPHA AND BETA ACTIVITY IN MINERAL WATER FROM SOUTHWEST BULGARIA

The natural radioactivity levels of mineral water from certain most frequently used sources in Southwest Bulgaria were determined. The mineral water was investigated with regard to gross alpha and beta activity to determine whether the activity concentrations are below levels at which no further action is required. The measurements were made by Liquid Scintillation Spectrometer. The gross alpha and beta activity varied from ≤ 0.003 Bq/L to 0.671 Bq/L and from 0.054 and to 0.375 Bq/L, respectively. The values obtained in this study were compared with data reported by other authors in different countries and with reference values accepted for drinking water. The annual effective doses were calculated for all investigated waters for adult inhabitants assuming yearly consumption of 730 litres. The results show that the annual effective dose of ingestion of these water samples excluding one, are below the individual dose criterion of 100 µSv/y according to the World Health Organization recommendations.

Reduction of the Renal Radioactivity of 111In-DOTA-Labeled Antibody Fragments with a Linkage Cleaved by the Renal Brush Border Membrane Enzymes.

The interposition of a cleavable linkage by enzymes on the renal brush border membrane constitutes a promising approach for reducing the renal radioactivity levels of radiolabeled low-molecular-weight antibody fragments and constructs (LMW Abs). Herein, we applied the molecular design to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-based reagents for radiotheranostic applications with trivalent radiometals. DOTA or a derivative thereof was conjugated to a Fab through an FGK linkage ([111In]In-DO3AiBu-Bn-FGK-Fab or [111In]In-DOTA-Bn-FGK-Fab). When injected into mice, both generated radiometabolites, [111In]In-DO3AiBu-Bn-F and [111In]In-DOTA-Bn-F, by the angiotensin-converting enzyme at similar rates. Both exhibited significantly lower renal radioactivity levels than a 111In-labeled Fab prepared by the conventional procedure ([111In]In-DOTA-Bn-SCN-Fab). The different elimination rates of each radiometabolite from the kidney significantly affected the renal radioactivity levels. [111In]In-DO3AiBu-Bn-FGK-Fab preferentially reduced the renal localization without impairing tumor accumulation. These findings would pave the way for developing a DOTA-based radiotheranostic platform for LMW Abs bearing cleavable linkers for renal brush border enzymes.