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The Sierra Peña Blanca (SPB) region in Chihuahua, Mexico contains a significant uranium deposit representing about 40% of the country's reserves. Common uranium minerals in this area include uranophane, schoepite, and weeksite/boltwoodite, with several superficial occurrences. Mining activities in the 1980s left unprocessed uranium ore exposed to weathering, with potential transport towards Laguna del Cuervo. This study presents an experimental simulation of uranium transport in SPB sediments using three approaches: (i) a batch experiment to evaluate the ideal adsorption of (UO2)2+ by fine sediment; (ii) a column system fed with 569 mgU L−1 UO2(NO3)2 to simulate adsorption by different sediment particle sizes; (iii) a column system with an upper horizon of uranophane from the area, fed with deionized water, to simulate uranium weathering and transport in particulate material, determined by liquid scintillation counting, revealed that the clay fraction had the highest adsorption capacity for U. X-ray Absorption Fine Structure (XAFS) analysis at the U L3 edge confirmed the U(IV) oxidation state and the fittings of the extended XAFS spectra confirmed the presence of the uranophane group of minerals. X-ray tomography further corroborated the distribution of particulate minerals along the column. The results suggest that the primary transport mechanism in SPB involves the fragmentation of uranium minerals, accompanied by eventual dissolution and subsequent adsorption of U onto sediments. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A potential link has been reported between skin exposure to aromatic amines, such as ortho-toluidine (OT) and 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA), and bladder cancer cases observed in Japanese chemical factories. To evaluate this association, we explored the permeability of OT and MOCA through pig skin and investigated the subsequent changes in plasma and urine concentrations in rats following percutaneous exposure. Employing Yucatan micropig skin, we first executed a permeability test by affixing the skin to a diffusion cell and applying 14C-labeled OT or MOCA. The receptor fluid's radioactivity was quantified at intervals of 1, 3, 6, 8, 24, and 48 h after application using a liquid scintillation counter. Next, we applied lint cloths drenched in OT and MOCA solutions to the backs of 7-week-old male F344 rats and monitored plasma and urine concentrations over time. Additionally, we investigated the pharmacokinetics of 14C-labeled OT or MOCA solutions for 8 h following percutaneous administration. Both OT and MOCA demonstrated high skin penetration; in particular, plasma concentrations significantly rose at 6 h for OT and 8 h for MOCA after exposure. However, OT was rapidly absorbed into the bloodstream and swiftly excreted into the urine, indicating quick absorbability. In contrast, MOCA penetrated the skin quickly but exhibited delayed bloodstream entry and urinary excretion, suggesting slower absorbability. Pharmacokinetic findings revealed the rapid urinary excretion of OT, whereas MOCA was excreted in the urine and potentially in the feces as well via bile. These findings indicate that implementing measures based on chemical absorbability could significantly enhance the management of industrial chemicals where percutaneous absorbability is a concern. [ABSTRACT FROM AUTHOR]

Introduction: CA102N is a novel anticancer drug developed by covalently linking H-Nim (N-(4-Amino-2-phenoxyphenyl methanesulfonamide) to Hyaluronic Acid to target CD44 receptor-rich tumors. The proposed approach seeks to enhance the efficacy and overcome limitations associated with H-Nim, including poor solubility and short half-life. Methods: The study aimed to evaluate the pharmacokinetics, biodistribution, metabolism, and tumor permeability of [14C] CA102N in xenograft mice following a single intravenous dose of 200 mg/kg. Liquid scintillation counting analysis was used for the pharmacokinetics and mass balance analysis. Metabolite profiling was assessed by HPLC-MS coupled with a radio flow-through detector. Quantitative Whole-Body Autoradiography was used to determine tissue distribution. Concentrations of CA102N and its metabolites were measured using total radioactivity data from urine, feces, and tissue samples. Results: About 94.9% of the administered dose was recovered at 240 h post-dose. The primary route of radioactivity elimination was through urine, accounting for an average of 77% of the dose with around 13.2% excreted in the feces. Tissue distribution showed rapid accumulation within 0.5 h post-administration, followed by a fast decline in most tissues except for the tumor, where slow elimination was observed. CA102N/metabolites exhibited a two-phase pharmacokinetic profile, characterized by an initial rapid distribution phase and a slower terminal elimination, with a half-life (t1/2) of 22 h. The mean maximum concentration (Cmax) of 1798.586 µg equivalents per ml was reached at 0.5 h (Tmax). Most of the radioactivity in plasma was attributed to CA102N, while small-molecule hydrolysis products dominated the excreta and tissue samples. Metabolite profiling revealed two major hydrolysis products: H-Nim-disaccharide and H-Nim-tetrasaccharide. No unchanged [14C] CA102N was detected in urine or feces, suggesting that CA102N undergoes extensive metabolism before excretion. Conclusion: The current data provided valuable insights into the pharmacokinetics, metabolism, and tissue/tumor distribution of CA102N in mice. These findings demonstrated that metabolic clearance is the primary elimination pathway for CA102N and that the drug exhibits tumor retention, supporting its development as an anticancer therapy. Our results provided a strong pharmacological basis for the advancement of CA102N into the clinic. [ABSTRACT FROM AUTHOR]

Background/Objectives: Riboswitches are functional nucleic acids that regulate biological processes by interacting with small molecules, such as metabolites, influencing gene expression. Artificial functional nucleic acids, including deoxyribozymes, have been developed through in vitro selection for various catalytic functions. In a previous study, an l-histidine-dependent deoxyribozyme was identified, exhibiting RNA cleavage activity in the presence of l-histidine resembling ribonuclease catalytic mechanisms. This study aims to clarify the role of l-histidine in the activity and structural formation of the l-histidine-dependent deoxyribozyme (HD), focusing on the binding properties and conformational changes of its derivative HD3. Methods: Conformational changes in HD3 were analyzed using circular dichroism (CD) under varying concentrations of l-histidine. Direct binding analysis was conducted using carbon-14 (14C)-labeled l-histidine and a liquid scintillation counter. The catalytic activity of HD3 in the presence of different l-histidine concentrations was measured. Results: The binding constant for l-histidine-induced conformational changes (Ka(CD)) was found to be 2.0 × 103 (M−1), whereas for catalytic activity (Ka(Rxn)) and scintillation counting (Ka(RI)), it was approximately 1.0 × 103 (M−1). Conclusions: l-Histidine plays an essential role in both the catalytic activity and structural formation of the HD3 deoxyribozyme. The consistent binding constants across different experimental methods highlight the significant contribution of l-histidine to the active folding of deoxyribozymes. [ABSTRACT FROM AUTHOR]

The growing concern over micropollutants in aquatic ecosystems motivates the development of electrochemical membrane reactors (EMRs) as a sustainable water treatment solution. Nevertheless, the intricate interplay among adsorption/desorption, electrochemical reactions, and byproduct formation within EMR complicates the understanding of their mechanisms. Herein, the degradation of micropollutants using an EMR equipped with carbon nanotube membrane are investigated, employing isotope-labeled steroid hormone micropollutant. The integration of high-performance liquid chromatography with a flow scintillator analyzer and liquid scintillation counting techniques allows to differentiate hormone removal by concurrent adsorption and degradation. Pre-adsorption of hormone is found not to limit its subsequent degradation, attributed to the rapid adsorption kinetics and effective mass transfer of EMR. This analytical approach facilitates determining the limiting factors affecting the hormone degradation under variable conditions. Increasing the voltage from 0.6 to 1.2 V causes the degradation dynamics to transition from being controlled by electron transfer rates to an adsorption-rate-limited regime. These findings unravels some underlying mechanisms of EMR, providing valuable insights for designing electrochemical strategies for micropollutant control. Pervasive micropollutants in aquatic environments pose significant threats to global water supply safety. Here, authors achieved permeate concentrations below the detection limit (2.5 ng/L) using a CNT-based electrochemical membrane, with the contributions of adsorption and degradation distinguished. [ABSTRACT FROM AUTHOR]

Soil contamination by the munition explosive residues of 2,4,6-trinitrotoluene (TNT) and its metabolites resulting primarily from military operations has been identified as a threat to human health and ecosystems. Biodegradation by native plants to remove this hazardous compound or reduce its toxicity is considered a cost-effective and environmentally sound approach for the cleanup or restoration of TNT-contaminated soils. This study aims to investigate the TNT biodegradation and kinetics by two selected native grasses in the species-specific rhizosphere soils through growth chamber experiments. Native eastern gamma grass (Tripsacum dactyloides) and switchgrass (Panicum virgatum L.) were grown in soil spiked with 14C-TNT for 8 weeks. The 14C-TNT degradation and degradative metabolite profile in the rhizosphere soils were determined by liquid scintillation counter and high-performance liquid chromatography, respectively. The results indicated that both native grass species significantly enhanced the TNT degradation in the rhizosphere soils as compared with the control rhizosphere soils. More than 95% of the applied 14C-TNT was degraded in the first 7 days, and the rate then reached a steady state afterward, but less than 10% of the TNT applied was completely mineralized and transformed into CO2. The degradative reaction was found to follow second-order kinetics. Six major TNT degradative metabolites have been detected and identified in the rhizosphere soils. Overall, switchgrass appeared more effective for biodegrading TNT than eastern gamma grass. This research demonstrated that the native grass species, especially switchgrass, has the potential to mitigate the adverse human health and ecological risks of TNT-contaminated sites and can be considered an environmentally friendly, sustainable approach to safeguarding human health from TNT contamination. [ABSTRACT FROM AUTHOR]

Objectives: This work aims to establish a dataset of ratios between tissue free water tritium (TFWT) and organically bound tritium (OBT) (containing both exchangeable and non-exchangeable OBT) in different types of seafood from Zhejiang province, China, thus to provide references for rapid screening of potential contamination of tritium in biological samples. Methods: Five types of seafood (fish, prawn, mussel, crab and kelp) were collected from Jiaxing, Ningbo, Zhoushan, Taizhou and Wenzhou city in Zhejiang Province in 2022, and measured for TFWT and OBT using tube furnace combustion system and liquid scintillation counting. Results: The observed activity concentrations of TFWT and OBT in this study were within the range of 1.01-10.09 Bq/L and 0.51-7.61 Bq/L, respectively. No significant difference in OBT/TFWT ratio was observed among different types of seafood (p > 0.05), among the geographic distribution of the five cities (p > 0.05), nor among the area of coastline, fishing ground and island (p > 0.05). Additionally, there was no significant difference in the OBT/TFWT ratio between seafood from area with and without nuclear power plant operation (p > 0.05). The mean OBT/TFWT ratio of fish, prawn, mussel, crab and kelp was 0.37 ± 0.19, 0.48 ± 0.27, 0.63 ± 0.33, 0.82 ± 0.50, and 0.64 ± 0.37, respectively. The mean and range of OBT/TFWT ratios were 0.59 ± 0.37 and 0.15-2.09 in all seafood collected from the five cities in Zhejiang Province, respectively. Conclusions: Our results indicate that tritium in seafood from coastal cities in Zhejiang Province is at the background level, and the operation of nuclear power plants in the province has no notable impact on the radioactivity levels of tritium in local marine biota. This study filled the gap in OBT/TFWT ratios in seafood, which provides new dataset for rapid detection of tritium contamination in nuclear emergencies. [ABSTRACT FROM AUTHOR]

Studying groundwater renewal time is a valuable tool to deepen the comprehension of sustainable groundwater resources specific to arid regions. Tritium is a radioactive isotope of hydrogen often used as an environmental tracer to study groundwater renewal time. The present work reports groundwater renewal times by the environmental tracer tritium to understand sustainable water resources in arid regions. First, groundwater samples were collected from wells in northeastern arid regions of Saudi Arabia. Then, an electrolysis process was employed to significantly increase the tritium level from twenty-five to thirty times the original concentration. Subsequently, the enriched water was analyzed using a liquid scintillation counter under optimized measurement conditions to determine the tritium concentration precisely. Two internationally recognized tritium laboratories conducted independent assessments to validate the estimated tritium levels. The verified tritium concentration was then used to estimate the groundwater renewal time using the Morgenstern and Pimenta curves. The results suggest that most of the monitored wells in the surveyed areas are more than a century old. Conversely, a few monitoring wells exhibit renewal times of several hundred years and may be considered nonrenewable water sources. These studies help to understand the geochemical characteristics of arid regions to ensure the sustainable management and protection of groundwater resources. [ABSTRACT FROM AUTHOR]

Groundwater is a critical resource in the Upper Chao Phraya basin, providing consistent water supplies for agricultural, domestic, and industrial activities, especially during the dry season. This study utilized tritium and carbon-14 dating techniques to investigate groundwater age, analyzing 273 samples collected in 2021 from various wells and depths across the basin. Tritium and carbon-14 were measured using liquid scintillation counting (LSC). The results revealed a wide range of groundwater ages, including recently recharged water with tritium concentrations up to 2.4 TU, corresponding to groundwater ages ranging from a few months to 44.17 years BP (Before Present), with an average of 18.26 years BP. Older groundwater was identified with carbon-14 concentrations as low as 3.22 pMC, indicating ages of up to 22,899 years, with a mean age of 6687 years BP. Correlation analysis showed a positive relationship between tritium and carbon-14 concentrations (r = 0.52). Spatial distribution patterns indicated that tritium concentrations were higher in northern and mountainous areas, identifying these as critical recharge zones. In contrast, lower carbon-14 concentrations in the central and southern areas suggested the presence of older groundwater, emphasizing the need for careful management of these ancient water reserves. The spatial variation in tritium and carbon-14 concentrations highlights differences in groundwater circulation and recharge patterns, enabling the identification of key recharge zones in the northern and highland regions. This highlights the importance of conserving these areas from pollution and over-extraction. The presence of old groundwater in the central and southern areas further emphasizes the need for ongoing monitoring to sustainably manage these long-term water resources. This study enhances the understanding of groundwater dynamics in the Upper Chao Phraya basin and provides valuable insights for improving water resource management strategies. [ABSTRACT FROM AUTHOR]

This article explores the role of l-arginine transport in the survival of Leishmania donovani, a parasite that causes Indian visceral leishmaniasis (VL), within macrophages. The study found that the availability of extracellular l-arginine is crucial for the survival of the parasite inside macrophages. The researchers also discovered that the CAT-2 isoform of the cationic amino acid transporter is associated with l-arginine transport in infected macrophages. The study suggests that targeting l-arginine metabolism and l-arginine-metabolizing enzymes could be a potential therapeutic strategy for treating VL. [Extracted from the article]

The inflammatory corpuscle recombinant absents in melanoma 2 (AIM2) and cholesterol efflux protein ATP binding cassette transporter A1(ABCA1) have been reported to play opposing roles in atherosclerosis (AS) plaques. However, the relationship between AIM2 and ABCA1 remains unclear. In this study, we explored the potential connection between AIM2 and ABCA1 in the modulation of AS by bioinformatic analysis combined with in vitro experiments. The GEO database was used to obtain AS transcriptional profiling data; screen differentially expressed genes (DEGs) and construct a weighted gene co-expression network analysis (WGCNA) to obtain AS-related modules. Phorbol myristate acetate (PMA) was used to induce macrophage modelling in THP-1 cells, and ox-LDL was used to induce macrophage foam cell formation. The experiment was divided into Negative Control (NC) group, Model Control (MC) group, AIM2 overexpression + ox-LDL (OE AIM2 + ox-LDL) group, and AIM2 short hairpin RNA + ox-LDL (sh AIM2 + ox-LDL) group. The intracellular cholesterol efflux rate was detected by scintillation counting; high-performance liquid chromatography (HPLC) was used to detect intracellular cholesterol levels; apoptosis levels were detected by TUNEL kit; levels of inflammatory markers (IL-1β, IL-18, ROS, and GSH) were detected by ELISA kits; and levels of AIM2 and ABCA1 proteins were detected by Western blot. Bioinformatic analysis revealed that the turquoise module correlated most strongly with AS, and AIM2 and ABCA1 were co-expressed in the turquoise module with a trend towards negative correlation. In vitro experiments demonstrated that AIM2 inhibited macrophage cholesterol efflux, resulting in increased intracellular cholesterol levels and foam cell formation. Moreover, AIM2 had a synergistic effect with ox-LDL, exacerbating macrophage oxidative stress and inflammatory response. Silencing AIM2 ameliorated the above conditions. Furthermore, the protein expression levels of AIM2 and ABCA1 were consistent with the bioinformatic analysis, showing a negative correlation. AIM2 inhibits ABCA1 expression, causing abnormal cholesterol metabolism in macrophages and ultimately leading to foam cell formation. Inhibiting AIM2 may reverse this process. Overall, our study suggests that AIM2 is a reliable anti-inflammatory therapeutic target for AS. Inhibiting AIM2 expression may reduce foam cell formation and, consequently, inhibit the progression of AS plaques. [ABSTRACT FROM AUTHOR]

Background: Escalating rates of obesity and public health messages to reduce excessive sugar intake have fueled the consumption of artificial sweeteners (AS) in a wide range of products from breakfast cereals to beverages. However, several observational and laboratory studies link AS consumption with increased appetite, food intake, weight gain and glucose intolerance(1-5). There are very few probing their effect on adipocytes. Therefore, we want to study the effect of different AS on glucose uptake in adipocytes. Aims and objectives: To study the effect of saccharin, sucralose and cyclamate on glucose uptake in 3T3 cell lines. Materials and methods: 3T3 cells from ATCC were grown in DMEM. A day prior to the experiment, they were incubated with varying concentration (untreated, 1nM, 1µM or 1mM) of one of the AS for basal uptake and another set of wells were treated with AS and 10nM insulin for stimulated uptake. After 24h incubation, glucose uptake was studied with radiolabeled 2-deoxy glucose by liquid scintillation counter and expressed per mg of protein. Results and Conclusion: 2-way Anova was done. Cyclamate and saccharin showed an increase in uptake with increase in concentration. But sucralose shows a significant decrease in uptake with increase in concentration. All AS do not have similar effect on glucose uptake by cells. Sucralose decreases the glucose uptake by cells and may not be the AS of choice in people who already have decreased glucose uptake. AS are not metabolically inert, and it will be necessary to choose the right AS based on the metabolic status of the individual. [ABSTRACT FROM AUTHOR]

During TRIGA reactor operation significant amounts of liquid radioactive waste are generated requiring appropriate management to ensure their safe disposal. Radiological characterization is an important activity needed to accomplish the waste acceptance criteria for different management steps including disposal. The purpose of this paper is to assess the activity concentrations of the ³1H. 383890Sr, 63286328Ni(difficult-to-measure), and gamma emitters (easy-to-measure) radionuclides in liquid radioactive waste generated by the TRIGA reactor operation and to establish a correlation among them to determine the scaling factors for this waste category. The radiological protocols applied for 6328Niand 3890Sr, separation and purification involve extraction chromatography using selective resins, while for H separation the distillation technique was applied. The assessment of gamma emitters was carried out using gamma-ray spectrometry and the detection of ³1H. 3890Sr, and 6328Niwas performed by liquid scintillation counting. The chemical yield of each experiment was determined by measuring the carrier added in each test by inductively coupled plasma optical emission spectrometry. The activity concentrations of 3890Sr, and 6328Niobtained were correlated with the activity concentration of 3860Co for establishing the scaling factor for the liquid radioactive waste stream. There were obtained good correlations but more experimental data are needed to determine the relevant scaling factors for these difficult-to- measure radionuclides. The scaling factors, once established, will improve and optimize the radiological characterization methodology applied for liquid radioactive waste as an easy and rapid method for assessment of concentration activities of difficult-to-measure radionuclides. Until now, no scaling factors data were reported for this liquid radioactive waste generated by TRIGA reactor operated by Institute for Nuclear Research Pitesti. The results obtained in this work represent preliminary data for establishing correlations between difficult-to-measure and easy-to-measure radionuclides and will be used for developing a scaling factor methodology. This will further be used to determine the inventory of difficult- to-measure radionuclides in different waste streams generated by TRIGA operation and decommissioning (foreseen after 2035). [ABSTRACT FROM AUTHOR]

We present data from six years (January 2016–December 2021) of monitoring the isotope composition of precipitation at the Sv. Urban station in Eastern Slovenia. The 68 precipitation samples were collected as a monthly composite. The complete dataset (193 data pints) includes information on the stable isotope composition of hydrogen (δ2H) and oxygen (δ18O) and tritium activity concentration (A), obtained using isotope ratio mass spectrometry (IRMS) and liquid scintillation counting (LSC) following electrolytic enrichment (EE), respectively. The isotope data, together with meteorological data, are reported. Calculations of the deuterium excess (d-excess), monthly, seasonal, and annual unweighted and precipitation-weighted means and local meteoric water lines (LMWLs) were conducted. The mean values for δ2H, δ18O, d-excess, and A, weighted by precipitation, were −59.9‰, −8.81‰, 10.6‰, and 7.7 TU. The disparities between unweighted and precipitation-weighted δ2H, δ18O, d-excess, A, and LMWLs underscore the significance of non-uniformly distributed precipitation. Annual variations in slope and intercept of the LMWLs emphasize the importance of longer data records (48+ months) to capture consistent trends, while combining data over longer periods may distort accuracy due to distinct isotope differences between individual years related to the variability of climate conditions typical for Slovenia. [ABSTRACT FROM AUTHOR]

Ciguatera, a global issue, lacks adequate capacity for ciguatoxin analysis in most affected countries. The Caribbean region, known for its endemic ciguatera and being home to a majority of the global small island developing states, particularly needs established methods for ciguatoxin detection in seafood and the environment. The radioligand receptor binding assay (r-RBA) is among the in vitro bioassays currently used for ciguatoxin analysis; however, similarly to the other chemical-based or bioassays that have been developed, it faces challenges due to limited standards and interlaboratory comparisons. This work presents a single laboratory validation of an r-RBA developed in a Cuban laboratory while characterizing the performance of the liquid scintillation counter instrument as a key external parameter. The results obtained show the assay is precise, accurate and robust, confirming its potential as a routine screening method for the detection and quantification of ciguatoxins. The new method will aid in identifying high-risk ciguatoxic fish in Cuba and the Caribbean region, supporting monitoring and scientific management of ciguatera and the development of early warning systems to enhance food safety and food security, and promote fair trade fisheries. [ABSTRACT FROM AUTHOR]

In this article the evaluation of the radon content in drinking water samples from the province of Reggio Calabria (Calabria, Southern Italy), is reported. In particular, the 222Rn activity concentration was measured by using the Liquid Scintillation Counting (LSC) PerkinElmer Tricarb 4910 TR setup, and it was compared with the parameter value (100 Bq L-1) reported in the Italian Legislative Decree 28/2016. The annual effective dose for the population of the investigated areas, due to the ingestion of 222Rn dissolved in water, was then evaluated only in those cases in which the parameter value was exceeded. Noteworthy, results reported in this paper represent a main reference for the investigated areas and constitute a baseline for future investigations regarding background radioactivity levels. [ABSTRACT FROM AUTHOR]

This study aims to determine the background levels of tritium radioisotope in drinking and seawater samples of Sinop province before the nuclear power plant was established in Sinop. In this context, a total of 174 water samples were collected, these are as follows: nine drinking water samples from the Sinop center and districts and 165 seawater samples from the seacoast from Samsun to Kastamonu. Tritium concentrations in the collected water samples were measured by the liquid scintillation counter. The minimum detectable activity for the method used was found to be 1.48 Bq/L. The tritium concentrations of the seawater and drinking water samples were found in the range of, MDA (minimum detectable activity)-6.29 Bq/L and 2.45-3.17 Bq/L, respectively. In addition, the annual effective dose rates of the people consuming these drinking waters due to the tritium radioisotope were calculated separately for infants, children and adults and found to be 12.12, 16.96 and 35.38 nSv, respectively. [ABSTRACT FROM AUTHOR]

Tritium levels in the groundwater of arid regions are very low; in most cases, these low tritium levels cannot be detected using a conventional liquid scintillation counter (LSC). To measure the tritium activity concentration, low-level tritium in groundwater needs to be enriched by a known factor so that the scintillation counter can detect it. An electrolysis process with electrolytic cells was designed and fabricated in our laboratory following the International Atomic Energy Agency (IAEA) instructions. Nine spiked samples with a known quantity of tritium were enriched, and the tritium activity concentration was measured using the scintillation counter. The enriched water exhibits a comparable level of spiked samples, albeit with some degree of uncertainty. A correlation was drawn among the tritium activity, enrichment factor, and the required time for the electrolysis procedure. This study confirmed that an enrichment process of approximately ten- to fortyfold of the initial concentration of the tritium could be achieved using the electrolysis process with the fabricated electrolytic cells. The simple design and fabrication of the electrolysis process by controlling various parameters make it affordable to measure low-level tritium using a conventional LSC. Various statistical analyses confirmed the accuracy and precision of the data obtained by the electrolysis process. This enrichment technique would prove valuable in regions where tritium levels in groundwater are extremely low, making them challenging to detect using conventional liquid scintillation counter. [ABSTRACT FROM AUTHOR]

Background: SHR8554 is a novel μ-opioid receptor-biased agonist. It has analgesic effects by selectively activating the G protein-coupled pathway. Additionally, it can weakly activate the ß-arrestin-2 pathway, resulting in a limited number of side effects, such as gastrointestinal inhibition. Previous studies have shown that SHR8554 has good analgesic effects, safety and tolerability, but the pharmacokinetic characteristics of SHR8554 in humans have not been reported. This study was designed to investigate the pharmacokinetics and safety of SHR8554 in healthy Chinese male subjects. Methods: A single 1 mg/41.3 μCi intravenous dose of [14C]SHR8554 was administered to six healthy male subjects. Blood, urine and faecal samples were collected at continuous time points to analyse SHR8554 parent drug levels and their metabolites. The total radioactivity in blood, plasma, urine and faeces was detected by using a liquid scintillation counter. The dynamic changes of SHR8554 and its metabolite concentration were by liquid chromatographytandem mass spectrometry (LC/MS), and then pharmacokinetic analysis. The safety of the drug on the subjects was also observed after a single intravenous injection. Results: The total recovery of radioactivity in urine and faeces was 99.68% ± 0.79% in 216 h, including 76.22% ± 1.12% in urine and 23.46% ± 1.36% in faeces. Seventeen major metabolites in blood, urine and faeces were analysed and identified. The main metabolic pathways of SHR8554 in the human body involve 1) N-dealkylation; 2) O-deethylation; 3) mono-oxidation; 4) glucuronidation, etc. The primary mechanism of SHR8554 clearance in the human body is through urinary excretion, primarily in its parent drug and metabolite forms. The drug has good safety, and no serious adverse effects were observed. Conclusion: SHR8554 showed favourable pharmacokinetic characteristics and safety profiles in this study. SHR8554 is extensively metabolized in human body. The main metabolic pathways include N-dealkylation and O-deethylation, as well as mono-oxidation and glucuronidation. The main excretion route of SHR8554 and its metabolites is through urine. Clinical Trial Registration: http://www.chinadrugtrials.org.cn/, identifier CTR20220450 [ABSTRACT FROM AUTHOR]

Natural tritium is widely dispersed in the environment, leading to human exposure to tritium through water ingestion, inhalation of tritium gas, and absorption through the skin. High levels of tritium in the environment can pose significant health risks due to the potential carcinogenic effects of tritium. Therefore, this study aims to estimate the tritium concentration in spiked water, rainwater, and groundwater by a liquid scintillation counter (LSC). Due to the lower detection levels of the LSC, an enrichment process of tritium ten- to thirtyfold was carried out using the electrolysis process. The enriched water was then analyzed to estimate the tritium concentration. Five reference samples were prepared by diluting a standard with known concentrations (spiked sample) to verify the precision of the measurement technique. The estimated tritium levels of the rainwater and the groundwater were within the 0.3 to 3.5 tritium units (TU) range. A comparatively higher tritium concentration was estimated for the shallow wells in the lower valley of the monitored areas. However, relatively lower concentrations were detected for wells located in the hillside areas. These findings will assist regulatory authorities in formulating strategies to ensure public safety by mitigating human exposure to tritium. [ABSTRACT FROM AUTHOR]

In this paper, the evaluation of the Rn-222 radioactivity content in drinking water samples from the Calabria region, southern Italy, is reported as a case study. The Rn-222-specific activity in the analyzed groundwater samples for human use was evaluated by using the PerkinElmer Tricarb 4910 TR setup and compared with the parameter value (100 Bq L−1) reported in the reference Italian legislation, i.e., D.Lgs. 28/2016, derived from the European Directive 2013/51/Euratom. The radiological health risk for the population of the investigated area, due to the ingestion and inhalation of Rn-222 dissolved in water, was then evaluated by calculating the total annual effective dose, only in those cases where the parameter value was exceeded. The obtained results represent a main reference for the investigated area and are useful for determining any possible radiological health risk for human beings related to the ingestion of the investigated radionuclide. Moreover, they can also be used as a baseline for future investigations regarding background radioactivity levels. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Liquid scintillation is widely used to quantify the activity of radioisotopes. We present an overview of the technique and its application to biogeosciences, particularly for turnover rate measurements. Microbial communities and their metabolism are notoriously difficult to analyze in low energy environments as biomass is exceedingly sparse and turnover rates low. Highly sensitive methods, such as liquid scintillation counting, are required to investigate low metabolic rates and conclusively differentiate them from the background noise of the respective analyzer. We conducted a series of experiments to explore the effects of luminescence, measurement time and temperature on scintillation measurements. Luminescence, the spontaneous emission of photons, disproportionally affects samples within the first few hours after sample preparation and can be minimized by following simple guidelines. Short measurement times will negatively affect liquid scintillation analysis or if background noise makes up a significant proportion of the detected events. Measurement temperature affected liquid scintillation analysis only when the temperature during the measurement reached approximately 30°C or higher, i.e. the liquid scintillation analyzer was placed in an environment without temperature control, but not in cases where chemicals were stored at elevated temperatures prior to measurement. Basic understanding on the functionality of a liquid scintillation analyzer and simple precautions prior to the measurement can significantly lower the minimum detection limit and therefore allow for determination of low turnover rates previously lost in the background noise. [ABSTRACT FROM AUTHOR]

Carbon-14 (14C) is a pure beta-emitting radionuclide with a half-life of 5730 ± 30 y. Considering the long half-life and its biological importance, significant attention is given to monitoring 14C in the vicinity of nuclear facilities. The 14C measurement technique employed by the majority of environmental monitoring laboratories for impact assessments in the vicinity of nuclear facilities is based on the thermal oxidization of the samples and the determination of activity by liquid scintillation counting. One of the difficulties faced by these laboratories is the nonavailability of a suitable matrix-matching reference material which is truly representative of the type of sample being analyzed. In this study, an effort has been made to develop a reference material that is representative and has a similar thermal oxidation/combustion property as that of a typical terrestrial plant biota observed in the vicinity of the nuclear power plants of India for quality assurance programs. A prebomb era wood (~150 years old) was identified as a potential secondary reference material. The stable carbon ratio (d13C) of the sample was determined by isotopic ratio mass spectrometer (IRMS), and the mean value was -26.33 ± 0.47 ?. The 14C specific activity of the sample was determined by accelerator mass spectrometry and a mean value of 221.6 ± 0.6 Bq kg-1 C was assigned as the reference value to the prebomb wood. In addition, measurements were performed by thermal oxidation in a tube furnace and by analysis of the 14C activity in a liquid scintillation counter. [ABSTRACT FROM AUTHOR]

Synovial fluid (SF) from human knee joints with osteoarthritis (OA) has elevated levels of lysophosphatidylcholine (LPC) species, but their functional role is not well understood. This in vitro study was designed to test the hypothesis that various LPCs found elevated in OA SF and their metabolites, lysophosphatidic acids (LPAs), modulate the abundance of proteins and phospholipids (PLs) in human fibroblast-like synoviocytes (FLSs), with even minute chemical variations in lysophospholipids determining the extent of regulation. Cultured FLSs (n = 5–7) were treated with one of the LPC species, LPA species, IL-1β, or a vehicle. Tandem mass tag peptide labeling coupled with LC-MS/MS/MS was performed to quantify proteins. The expression of mRNA from regulated proteins was analyzed using RT-PCR. PL synthesis was determined via ESI-MS/MS, and the release of radiolabeled PLs was determined by means of liquid scintillation counting. In total, 3960 proteins were quantified using multiplexed MS, of which 119, 8, and 3 were significantly and reproducibly regulated by IL-1β, LPC 16:0, and LPC 18:0, respectively. LPC 16:0 significantly inhibited the release of PLs and the synthesis of phosphatidylcholine, LPC, and sphingomyelin. Neither LPC metabolite—LPA 16:0 nor LPA 18:0—had any reproducible effect on the levels of each protein. In conclusion, small chemical variations in LPC species can result in the significantly altered expression and secretion of proteins and PLs from FLSs. IL-1β influenced all proteins that were reproducibly regulated by LPC 16:0. LPC species are likely to modulate FLS protein expression only in more advanced OA stages with low IL-1β levels. None of the eight proteins being significantly regulated by LPC 16:0 have been previously reported in OA. However, our in vitro findings show that the CD81 antigen, calumenin, and B4E2C1 are promising candidates for further study, focusing in particular on their potential ability to modulate inflammatory and catabolic mechanisms. [ABSTRACT FROM AUTHOR]

The hydrogen radioactive isotope, tritium, not only reflects seasonal variation in precipitation but also variations on a local level. To use this radioisotope in authentication and geographical indication procedures, the tritium levels in vines, grapes, and wine were measured in two forms: (1) tissue-free water tritium (TFWT), measured in the free water of the plant or the aqueous phase of the wine; (2) organically bound tritium (OBT), measured in the organic part of the plant or wine (as ethanol). This paper presents the tritium behavior in vines from May to October and in the wine produced from harvested grapes for both tritium forms (TFWT and OBT) in connection with environmental tritium concentrations in air and precipitations during the 2019–2023 vegetation periods near the Râmnicu Vâlcea city. If the tritium of tissue-free water was influenced by precipitation and air humidity during the harvest period, the organically bound tritium recorded a maximum level with a delay of 1–2 months compared with tritium’s seasonal variation in precipitation and air. The tritium values of early mean in precipitation and ethanol from wine were approximately an average value of 11 TU for all 5 years of observations.

The aim of this study was to analyse a capability of carbon-containing nanoparticles (CNPs) obtained by heating of organics, to influence mercury-induced neurotoxicity in biological system, such as presynaptic rat cortex nerve terminals. Methods. CNPs were obtained using method described in [6] by the combustion of citric acid and urea. The cortex nerve terminals isolated from Wistar rats were used in the experiments. [14C] glutamate uptake and release in the nerve terminals were monitored using a radiolabelled assay. In particular, rat brain nerve terminals (synaptosomes) were isolated from the rat cortex. The cortex regions were rapidly removed and homogenized in the ice-cold solution consisted of: sucrose 0.32 M; HEPES-NaOH 5 mM, pH 7.4; EDTA 0.2 mM. One synaptosomal preparation was isolated from one rat. The synaptosomes from brain homogenate were obtained according to the procedure proposed by Cotman with minor modifications [7] by differential centrifugation and Ficoll-400 density gradient centrifugation. The concentrations of proteins were monitored according to Larson. To measure the uptake of L-[14C] glutamate, the synaptosomal suspension was pre-incubated in the standard saline solution. Then, HgCl2 was applied to the synaptosomal incubation media, and synaptosomes were further incubated for 6 min before starting the uptake, which in turn was initiated by the application of the aliquots of non-radiolabelled L-glutamate (10 μM) supplemented with L-[14C] glutamate, 420 nM, 0.1 μCi/ml, and then the synaptosomes were incubated at 37 °C during 1 min to measure the initial rate of L-[14C] glutamate uptake. L-[14C] glutamate uptake was monitored with liquid scintillation counting using the ACS scintillation cocktail, 1.5 ml [8]. To measure the extracellular level of L-[14C] glutamate, the synaptosomes were were preincubated at 37 °C during 10 min to restore the ion gradients, and after that they were loaded with L-[14C] glutamate, 1 nmol per mg of protein, 238 mCi/mmol, in the standard saline solution at 37 °C during 10 min according to [9]. Total synaptosomal content of L-[14C] glutamate was equal to 200000±15000 cpm/mg protein. Results. In the first sets of the experiments, Hg2+ effects on the extracellular level of L-[14C] glutamate were assessed in nerve terminal preparations (Fig.1). It was shown a mercury-induced excitotoxic increase in the ambient level of L-[14C] glutamate in nerve terminal preparations. In the second sets of the experiments (Fig. 2), it was demonstrated that Hg2+ decreased the initial rate and accumulation of L-[14C] glutamate by nerve terminals starting from a concentration of 10 μM. Therefore, it was shown that a mercury-induced excitotoxic increase in the ambient level of L-[14C] glutamate in nerve terminal preparations (Fig. 1) resulted from weak functioning of glutamate transporter, and so significantly decreased L-[14C] glutamate uptake (Fig. 2). In the third sets of the experiments, it was shown that CNPs from heating of citric acid/urea mitigated an excitotoxic mercury-induced increase in the extracellular level of L-[14C] glutamate in nerve terminal preparations. The latter was equal to 0.425 ± 0.023 nmol/mg of proteins after combined application of HgCl2 (5 μM) and CNPs (1 mg/ml) (Р ≤ 0.05 as compared to effect of Hg2+per se; n = 6) and 0.460 ± 0.017 nmol/mg of proteins after combined application of HgCl2 (5 μM) and CNPs (10 mg/ml) (Р ≤ 0.05 as compared to effect of Hg2+ per se; n = 6). Therefore, CNPs were able to mitigate in an acute manner excitotoxic Hg2+-induced increase in the extracellular L-[14C]glutamate level in nerve terminals by 37%, thereby being a provisional Hg2+ scavenger. Conclusions. CNPs can mitigate Hg2+-induced excitotoxicity in nerve terminals. Taking into account this fact, it can be assumed that these nanoparticles can be used as Hg2+ adsorbent in the human organism. Besides biotechnological implementation of data, developed approach can be applicable for monitoring capability of different particles and compounds to mitigate Hg2+-mediated threat. [ABSTRACT FROM AUTHOR]

Introduction: Previous studies have established that endogenous inorganic polysulfides have significant biological actions activating the Transient Receptor Potential Ankyrin 1 (TRPA1) receptor. Organic polysulfides exert similar effects, but they are much more stable molecules, therefore these compounds are more suitable as drugs. In this study, we aimed to better understand the mechanism of action of organic polysulfides by identification of their binding site on the TRPA1 receptor. Methods: Polysulfides can readily interact with the thiol side chain of the cysteine residues of the protein. To investigate their role in the TRPA1 activation, we replaced several cysteine residues by alanine via site-directed mutagenesis. We searched for TRPA1 mutant variants with decreased or lost activating effect of the polysulfides, but with other functions remaining intact (such as the effects of nonelectrophilic agonists and antagonists). The binding properties of the mutant receptors were analyzed by in silico molecular docking. Functional changes were tested by in vitro methods: calcium sensitive fluorescent flow cytometry, whole-cell patch-clamp and radioactive calcium-45 liquid scintillation counting. Results: The cysteines forming the conventional binding site of electrophilic agonists, namely C621, C641 and C665 also bind the organic polysulfides, with the key role of C621. However, only their combined mutation abolished completely the organic polysulfide-induced activation of the receptor. Discussion: Since previous papers provided evidence that organic polysulfides exert analgesic and anti-inflammatory actions in different in vivo animal models, we anticipate that the development of TRPA1-targeted, organic polysulfide-based drugs will be promoted by this identification of the binding site. [ABSTRACT FROM AUTHOR]

With the current state of water scarcity in Mafikeng, South Africa, due to low water levels and an increasing population, it is therefore crucial to ensure the sustainability and availability of the existing water resources. In this study, the levels of tritium and radiocarbon in groundwater (boreholes) at selected villages in Mafikeng were determined using the Perkin Elmer Ultra Low Liquid Scintillation Counter 2000. The mean activity concentrations of tritium are 3.61304 ± 0.00612 Bq/L and 3.86014 ± 0.00739 Bq/L for samples from Dibate and Lokaleng villages, respectively, whereas 1.83392 ± 0.02265 Bq/L is for Moletsamongwe, Lekung, Airport View and Seweding. Moreover, the mean activity concentrations of radiocarbon from Dibate and Lokaleng are 0.59296 ± 0.00886 Bq/L and 0.8333 ± 0.0126 Bq/L, respectively, whereas for, Moletsamongwe, Lekung, Airport View and Seweding, they are 1.3752713 ± 0.01968 Bq/L. Two (2) out of the forty (40) samples analysed for radiocarbon are below the minimum detectable activity of 0.33627 Bq/L. The average annual effective dose (AED) of tritium for analysed samples from Dibate and Lokaleng villages are 0.04754 μSv/y and 0.05079 μSv/y, respectively, whereas it is 0.02413 μSv/y for Moletsamongwe, Lekung, Airport View and Seweding. The average AED for radiocarbon is 0.251404 μSv/y and 0.36604 μSv/y for samples from Dibate and Lokaleng, respectively, whereas it is 0.58309 μSv/y for Moletsamongwe, Lekung, Airport View and Seweding village. The evaluated lifetime cancer risk for mortality and morbidity in adults is lower than the radiological cancer risk limit of 1.63 × 10−3 set by regulatory agencies; hence, the consumption of the studied groundwater from the selected villages will not pose any health risks in terms of tritium and radiocarbon levels. [ABSTRACT FROM AUTHOR]

In this work, the concentration of tritium in D2O of various degrees of purity was measured. Samples were taken from the Arak heavy water plant and tritium concentrations were determined using a liquid scintillation detector (LSC) based on tritium decay. In the present work, instead of simple distillation, is used the azeotropic distillation method. Absorption and fluorescence spectra were recorded using a Shimadzu UV-2100 spectrometer and an LS50B fluorescence spectrometer. The tritium concentration in the samples varied from 1.75 ± 0.80 to 6.16 ± 1.01 Bq.L-1 in D2O enrichment from 0.35% to 77.50%. The correlation coefficient between tritium concentration and D2O purity in heavy water was obtained as R² = 0.853. Deviation for 99.8% D2O enriched in heavy water. This was observed from a straight line, leading to a drop in R². The results of this measurement showed that the tritium concentration did not exceed the value set by the Nuclear Regulatory Commission (NRC). [ABSTRACT FROM AUTHOR]

Nonetheless, the content of photosynthetic pigments (chlorophylls and carotenoids) in I T. japonicum i roots was approximately half of that in the leaves, whereas the pigment content in I T. aphyllum i roots was similar to that in I T. japonicum i leaves (Fig. Keywords: 14CO2 labeling; carbon acquisition; chlorophyll fluorescence; crassulacean acid metabolism (CAM); Orchidaceae; radioisotope EN 14CO2 labeling carbon acquisition chlorophyll fluorescence crassulacean acid metabolism (CAM) Orchidaceae radioisotope 932 937 6 04/03/23 20230501 NES 230501 Orchidaceae is one of the most diverse families of flowering plants, with > 28 000 known species distributed among 763 genera (Christenhusz & Byng, [8]). Moreover, the high nocturnal C fixation by I T. aphyllum i roots comparable to that by I T. japonicum i leaves indicates sophisticated C fixation in I T. aphyllum i roots. [Extracted from the article]

Due to its short half-life (87 days), naturally occurring radio-sulfur (35S) is applicable as aqueous environmental tracer for investigating groundwater residence times shorter than one year. Being a pure β-decaying radionuclide, 35S is detected straightforwardly by means of liquid scintillation counting (LSC). The rather low 35S activities in natural waters require (i) a careful sample preparation aiming at extracting 35SO 4 2− from large-volume water samples (ca. 20 L) resulting in samples ready for LSC measurement and (ii) an optimal device-specific setup of the LSC to maximize the 35S signal-to-noise-ratio. A few publications that discuss approaches for sample preparation and device-specific LSC setup optimization are available. This paper presents a summarizing step-by-step instruction for both optimized sample preparation and LSC setup. For practical reasons, two different sample preparation approaches are presented, one for samples with low total sulphate inventories (up to 350 mg) and one for samples with elevated total sulphate inventories (350–1500 mg). LSC setup optimization aiming at the measurement of the two resulting types of samples is described for three LSC devices, namely Quantulus GCT, TriCarb 3170 TR/SL, and Quantulus LB 1220. • 35S can be used as a tracer for detecting sub-yearly groundwater ages. • Sulphate (35SO 4 2−) has to be extracted from voluminous water samples for LSC measurement. • Extraction by (i) use of ion-exchange resin or (ii) BaSO 4 precipitation depending on sulphate inventory of water sample. • LSC setup is required for counting window optimization and quench reduction. • Paper gives step-by-step instruction for sample preparation and LSC setup. [ABSTRACT FROM AUTHOR]

The relevance. One of the relatively long-lived nuclear fission products is 151Sm (T1/2~90 years). The total cumulative yield of 151Sm upon fission of the isotopes 235U, 239Pu and 238U is 0,46, 1,29 and 0,83 %, respectively. The estimated amount of 151Sm that could have been dispersed during ground and atmospheric tests at Semipalatinsk test site is 6,1·105 Ci. The current situation with the levels of radioactive contamination of the soil cover with this radionuclide is still unknown. The aim of the research is to develop the method for radiochemical determination of 151Sm in Semipalatinsk test site soils using liquid scintillation spectrometry. Objects. Surface soil samples were taken from the territory of the former Semipalatinsk test site. The main sampling criteria were the presence of 137Cs as a possible indicator of the presence of 151Sm and the absence of radioactive isotopes of Eu as the main interfering radionuclide. The specific activity of 137Cs in the samples under study varied from 3,6 to 780 Bq/kg. Methods. The proposed method for 151Sm determination includes complete dissolution of the samples with concentrated acids (HF and HNO3 and their mixtures), isolation and radiochemical purification with ion exchange resins, as well as precipitation of poorly soluble substances. In order to determine the chemical yield, 0,5 mg of Sm-carrier was added to each sample as an indicator. The quenching curve for 151Sm was prepared using the CIEMAT/NIST approach. The 151Sm specific activity was measured using Quantulus 1220 LSC. Results. The radiochemical purification of the 151Sm fraction from interfering beta emitters was analyzed and evaluated, as well as the effect of natural samarium on the chemical yield. The contribution of natural samarium regarding to the clarke does not exceed 8 % (for 5 g soil sample), and in relation to the experimentally measured amount – 0,5 %. However, it seems more expedient to double the amount of the added carrier (up to 1 mg per sample), which will reduce the contribution of natural samarium to 4 % (relative to the clarke). Gamma-spectrometric measurements of the isolated samarium fraction indicate the possibility of its contamination with some residual amount of strontium isotopes (85Sr was used as an indicator), the maximum amount of which, obviously, does not exceed 5 %. The specific activity of all other considered radionuclides is below the detection limits. MDA value obtained for 151Sm in this work was in the region of 0,01 Bq/g. The mean chemical recovery of 151Sm was 83 %. The specific activity of 151Sm in surface soil ranged from 158 to 290 Bq/kg.

Lactosylceramide is necessary for the biosynthesis of almost all classes of glycosphingolipids and plays a relevant role in pathways involved in neuroinflammation. It is synthesized by the action of galactosyltransferases B4GALT5 and B4GALT6, which transfer galactose from UDP-galactose to glucosylceramide. Lactosylceramide synthase activity was classically determined in vitro by a method based on the incorporation of radiolabeled galactose followed by the chromatographic separation and quantitation of the product by liquid scintillation counting. Here, we used deuterated glucosylceramide as the acceptor substrate and quantitated the deuterated lactosylceramide product by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). We compared this method with the classical radiochemical method and found that the reactions have similar requirements and provide comparable results in the presence of high synthase activity. Conversely, when the biological source lacked lactosylceramide synthase activity, as in the case of a crude homogenate of human dermal fibroblasts, the radiochemical method failed, while the other provided a reliable measurement. In addition to being very accurate and sensitive, the proposed use of deuterated glucosylceramide and LC-MS/MS for the detection of lactosylceramide synthase in vitro has the relevant advantage of avoiding the costs and discomforts of managing radiochemicals. [ABSTRACT FROM AUTHOR]

Strongylocentrotus nudus egg polysaccharide (SEP) extracted from sea urchins has potential anticancer activity. However, little is known about its pharmacokinetic properties. To investigate the pharmacokinetics of SEP, it was radiolabeled with tritium. Furthermore, a sensitive, selective, and rapid liquid scintillation counter (LSC) method for quantifying 3H-SEP in biological matrix was validated. The lower quantification limit of the method was 4 Bq. The relative standard deviations (RSDs) of the intra- and inter-day precision were <3.0% and <3.9%, respectively. 3H-SEP was successfully applied to investigate the pharmacokinetics of SEP after intravenous administration of 20, 40, and 80 mg/kg (40 µCi/kg) in rats and 5, 10, and 20 mg/kg (6 µCi/kg) in beagles. The AUC(0-t) of SEP at three different doses was 487.81 ± 39.99 mg/L*h, 1,003.10 ± 95.94 mg/L*h, and 2,188.84 ± 137.73 mg/L*h in rats and 144.12 ± 3.78 mg/L*h, 322.62 ± 28.03 mg/L*h, and 754.17 ± 37.79 mg/L*h in beagles. The terminal elimination half-life (t1/2) of SEP was longer in beagles (204.29 ± 139.34 h) than in rats (35.48 ± 6.04 h). The concentration of SEP in plasma declined rapidly in both rats and beagles. All the study results provide detailed pharmacokinetic profiles of SEP in two kinds of animals, which will be helpful for further development. [ABSTRACT FROM AUTHOR]

The article reports on a study that shows long-term nitrogen fertilization can increase the release of ancient carbon (C) from deep critical zones, resulting in more carbon dioxide (CO2) emissions. It also mentions that this increase in nitrogen input resulting from anthropogenic activity is considered responsible for the activation of "sleeping" carbon in deep soils, including the need for improved nitrogen management in fertilized agricultural soils.

In living beings, antioxidants are of vital importance for protection against oxidative damage caused by reactive oxygen species. Silymarin (SM), a plant-derived flavonoid present in the fruits and seeds of milk thistle Silybum marianum (L.) Gaertn., has a recognized hepatoprotective effect. In this work, the in vitro silymarin antioxidant effect on non-enzymatic peroxidation (NEP) in chicken liver mitochondria and microsomes was studied. Oxidative stress in the organelles was induced by subjecting the samples (1 mg of protein) to an ascorbate-Fe++-dependent prooxidant system at 37 °C. Oxidative damage was quantified by chemiluminescence (CL) using a Packard1900 TR liquid scintillation counter (Meriden CT, USA). CL expressed as cpm (counts per minute) was read every 10 minutes to establish the course of peroxidation as a function of time. Likewise, the total cpm value (sum of the readings) was used to compare the inhibitory effect of SM using different concentrations corresponding to 6.25; 12.5, and 25 μg of the active ingredient (silymarin phosphatide) per mg of mitochondrial and microsomal protein. Controls were run simultaneously without the addition of ascorbate. Peroxidation inhibition was dependent on the concentration of SM in the incubation mixture. The results show that a protective effect on induced oxidative damage was found for all concentrations tested. [ABSTRACT FROM AUTHOR]

This work presents a development of a new radiocarbon dating system based on CO2 and liquid scintillation counting. The system is flexible enough to be applied in different fields such as radiocarbon dating (up to about 32 000 years span), environmental radioactive monitoring, and determining the fraction of biological carbon in environmentally-ecologically safe biodegradable and bio-synthetic products, and help accreditation to customaries. The implemented system is developed following the standard method (ASTM D6866-06). It has been calibrated tested and verified for CO2 production, absorption, and counting (using appropriate reference materials for the present-day, fossil, and in between ages). These results are optimistic that the developed system can contribute to the accreditation of ongoing and upcoming environment-friendly productions. [ABSTRACT FROM AUTHOR]

Radon is one of the most natural forms of radiation for human exposure. However, high-accuracy measurement of natural radon in water samples is very challenging due to the background correction, data acquisition, and sampling time. Liquid scintillation counter (LSC) and semiconductor alpha spectroscopy detectors are the most commonly used methods of determining radon concentration in water. The present study utilizes both methods to estimate radon in groundwater collected from various locations in the northeast region of Saudi Arabia. The estimated radon concentrations using Hidex 300SL are compared with a Durridge RAD7 detector to evaluate each apparatus's abilities, advantages, and disadvantages. Both methods show radon concentrations between 0.1 and 3.20 Bq/L with an average of 0.96 Bq/L, with a standard deviation of 0.82 Bq/L. The estimated values are found to be in the safe limit recommended by the USEPA and EAEC and are far below the safe level recommended by UNSCEAR and the WHO. Comparing the estimated radon concentration using the two methods shows that although the two devices have many advantages and disadvantages based on the two different techniques, the experimental results are almost the same with experimental error. [ABSTRACT FROM AUTHOR]

To date, the world has accumulated a large amount of long-lived radioactive materials that need to be disposed of or reprocessed. Such materials include nuclear legacy objects containing 226Ra, which is an important material for obtaining a wide range of isotopes for nuclear medicine via irradiation in reactors, cyclotrons, and electron accelerators. For the selective recovery of 226Ra from waste materials, crown-ether (CE) 18-crown-6 (18C6) or its derivatives can be used, which, however, have not been widely studied for these purposes. In our work, the key property of 18C6 and its derivatives, the phase distribution, was studied using tritium labeling. The possibility of introducing a tritium label into CEs molecules using thermal activation of tritium has been demonstrated; a high specific activity of the obtained compounds was achieved (from 18 to 108 TBq/mol). Methods for chromatographic purification of the studied CEs were developed. The distribution of 18C6 and its derivatives between various organic solvents and water was studied in detail for the first time. Subsequently, the obtained data will allow us to choose conditions for the selective recovery of 226Ra from aged sources. [ABSTRACT FROM AUTHOR]

Consumption and drinking of healthy and high-quality water is considered an important matter in human life, so monitoring of drinking water pollution including radioactive contamination and assessing the amount of radiation exposure of people through water consumption is very important. The purpose of this investigation was to measure the concentration of gross beta and alpha activities in water samples collected from Tehran water sources. In the present study, the gross beta and alpha activity concentrations of 35 water samples in Tehran were analyzed and measured to evaluate their radiological quality using liquid scintillation method. The results of the analysis showed the activity concentration of gross alpha ranges from 48 mBq/L to 227 mBq/L with a mean of 137.5 mBq/L. the activity concentration of gross beta in the samples ranged from 49 mBq/L to 328 mBq/L with a mean of 184.7 mBq/L. Also, the correlation coefficient between the results were very strong and equal to 0.87. The results showed that the gross beta and alpha activity concentrations in all waters was lower than the standard limit of the World Health Organization (WHO) and the Institute of Standards and Industrial Research of Iran, which is 500 mBq/L and 1000 mBq/L, respectively and also waters are radiologically healthy.

Objective: To figure out the source of uncertainty in the determination of 14C activity concentration in urine samples, and to establish a complete expression of analysis results, in order to improve the accuracy of 14C monitoring method. Methods: Four urine samples of normal people were collected, and wet oxidation method was used in the pretreatment of the samples, then the activity concentration of 14C was determined by liquid scintillation counting (LSC). After the mathematical model was established, the uncertainty components were determined, the standard uncertainty was combined, and the extended uncertainty was calculated. Results: The relative uncertainty of 4 samples was 22.5%, 17.0%, 17.3% and 18.2%. The activity concentration of urine was (0.32 ​± ​0.14), (0.60 ​± ​0.20), (0.86 ​± ​0.30) and (0.74 ​± ​0.27) Bq/L, respectively. In the relative uncertainty of 22.5%, 17.7% was from sample counting, 13.6% from detection efficiency, 2.1% from recovery rate, 0.58% from sample volume, and 0.01% from sample weight. Conclusions: The main factors affecting the uncertainty include the error or deviation of sample counting, detection efficiency and recovery rate. The error of volume and weight also contributes to the measurement uncertainty.