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Waters recharging the subsurface contain a variety of naturally occurring geochemical components, the concentrations of which are principally a function of the atmosphere and surface environment. Over time, water-rock interactions and radiogenic processes in the subsurface control a complex geochemical evolution, impacting the initial surface-related signatures associated with recharged groundwaters. The rates of these geochemical changes are considerable in many important geologic settings, requiring characterisation and quantification of the dominant subsurface processes and evolving fluid characteristics. Constraining this is critically important for the discipline of fluid 'age' dating - hydrogeochronology. Age dating, or quantification of fluid residence times is typically evaluated through two categories of tracers; those that are incorporated at the point of recharge and decrease over time through radioactive decay (e.g. 3H, 14C, 81Kr) and those that increase over time (e.g. radiogenic noble gases) due to subsurface production and accumulation in fluids. As these fluids, elements, and tracers have different provenance, the calculated 'age' of any fluid represents the average, or mean residence time, of all components. Likewise, additional mechanisms of subsurface tracer production or loss can have significant bearing on any element-specific calculated residence times. The inevitable temporal discrepancies between tracers can be generated or accentuated in the subsurface which can prove difficult to reconcile in hydrogeochronologic modelling approaches. By incorporating geochemical data into existing neutron flux-based models, this study evaluates specifically how subsurface production of 'diminishing' tracers in the fluid phase, via neutron capture of parent elements, can produce complexity in the dating of host fluids. The in situ rates and production routes of 3H, 14C, 36Cl 39Ar, and 81Kr in different subsurface fluids are modelled for a variety of host rock lithologies to evaluate the effect such baseline crustal production in different geochemical settings may have on calculated residence times within naturally occurring systems. In particular this model provides a quantitative evaluation for how site-specific subsurface radiogeochemistry may result in enhanced baselines of 36Cl, 39Ar, (and potentially 14C) relative to canonical assumptions, and substantially impact residence time estimates calculated from these tracers for a range of subsurface environments. Additionally, we evaluate the role geologic environments can have on low levels of baseline production and calculated residence times for 3H and 81Kr. This study quantitatively evaluates the dependence of geologic environments on these subsurface processes and the impacts this may have on hydrogeochronologic studies. The ability to quantify production of tracers in the subsurface and recalibrate associated residence times in a wide range of geologic settings is of direct relevance to areas such as groundwater resource management, Carbon Capture and Storage, hydrogen storage and nuclear waste management strategies, the hydrocarbon and energy industry, and investigations of the timing and evolution of subsurface microbial life. [ABSTRACT FROM AUTHOR]

In cardiotoxicity, PET/MR affords an accurate evaluation of cardiovascular morphology, function, and also multi-parametric tissue characterization. A composite of several cardiac imaging parameters provided by the PET/MR scanner is likely to outperform a single parameter or imaging modality in the assessment and prediction of the severity and progression of cardiotoxicity but needing clinical investigations. Of particular interest, a heterogeneity map of single PET and CMR parameters could be perfectly correlated with the PET/MR scanner likely emerging as a promising marker of cardiotoxicity to monitor treatment response. While such functional and structural multiparametric imaging approach with cardiac PET/MR in the assessment and characterization of cardiotoxicity holds much promise, its validity and value in cancer patients treated with chemotherapy and/or radiation still needs to be assessed. The multi-parametric imaging approach with PET/MR, however, is likely to set new standards to develop predictive constellations of parameters for the severity and potential progression of cardiotoxicity that should afford timely and individualized treatment intervention to ascertain myocardial recovery and improved clinical outcome in these high-risk patients. • In cardiotoxicity, PET/MR affords an accurate evaluation of cardiovascular morphology, function, and also multi-parametric tissue characterization • A composite of several cardiac imaging parameters provided by the PET/MR scanner is likely to outperform a single parameter or imaging modality in the assessment and prediction of the severity and progression of cardiotoxicity but needing clinical investigations • Heterogeneity map of single PET and CMR parameters could be perfectly correlated with the PET/MR scanner likely emerging as a promising marker of cardiotoxicity to monitor treatment response [ABSTRACT FROM AUTHOR]

5-Chloro-2-methyl-4-isothiazolin-3-one (CMIT) and 2-methyl-4-isothiazolin-3-one (MIT) used as preservatives in various products, including humidifier disinfectants, presents substantial health hazards. This research delves into the toxicological assessments of CMIT/MIT in the respiratory system using animal models. Through the synthesis of radiolabeled [14C]CMIT and [14C]MIT, we investigated the biological uptake and in vivo behaviors of CMIT/MIT in the respiratory tissues following intratracheal exposure. Quantitative whole-body autoradiography (QWBA) revealed significant persistence of CMIT/MIT in lung tissue. In addition, radio high-performance liquid chromatography (radio-HPLC) with tandem mass spectrometry (LC-MS/MS) was employed for metabolite profiling and identification. Notably, around 28% of the radiolabel was retained in tissue after the extraction step, suggesting covalent binding of CMIT/MIT and their metabolites with pulmonary biomolecules. This observation demonstrates the propensity of the electrophilic isothiazolinone ring in CMIT/MIT to undergo chemical interactions with biothiols in proteins and enzymes, fostering irreversible alterations of biomolecules. Such accumulations of transformations could result in direct toxicity at both cellular and organ levels. Additionally, the detection of metabolites, including a MIT dimer conjugated with glutathione (GSH), as analyzed by mass spectrometry indicates the possible reduction of cellular GSH levels and subsequent oxidative stress. This investigation offers an in-depth insight into the toxic mechanisms of CMIT/MIT, underlying their capability to engage in complex formations with biomacromolecules and induce pronounced respiratory toxicity. These results highlight the imperative for stringent safety assessments of these chemicals, advocating for improved public health and safety measures in the use of chemicals. [Display omitted] • The radiolabeled CMIT and MIT were synthesized using radioactive carbon (14C). • The SUV of CMIT/MIT in lung was determined to be 6.01 after 0.083 h post exposure. • In the analysis of metabolites, the parent structures of CMIT/MIT were not observed. • Some metabolites were found to be conjugated with glutathione. • Approximately 28% of the radiolabel was bound to pulmonary biomolecules. [ABSTRACT FROM AUTHOR]

El abordaje quirúrgico de las distintas enfermedades, no solo oncológicas, ha evolucionado. Como ha sido acuñado de forma muy gráfica por el grupo de Veronesi, estamos pasando de los «tratamientos máximos tolerables a los mínimos eficaces» y este recorrido no puede ser llevado a cabo de otra forma que mediante un planteamiento de trabajo multidisciplinar y multimodalidad. Obligatoriamente multidisciplinar porque es necesaria la colaboración entre cirujanos, oncólogos, radiólogos, médicos nucleares, patólogos y todo aquel relacionado con el seguimiento de los pacientes, y obligatoriamente multimodalidad porque nos debemos encaminar hacia una cirugía de precisión a la medida de cada paciente en la que, por parte de la Medicina Nuclear, tiene mucho que decir la imagen híbrida (SPECT/TC y PET/TC), los trazadores bimodales, el empleo de nuevos aliados como la ecografía o nuestra propia adaptación a la cirugía robótica. Todo un amplio abanico de posibilidades construido a partir de un sólido cimiento como es la gammagrafía preoperatoria, que posibilita la identificación de los tejidos diana y cuyo conocimiento previo a la intervención permite plantear el abordaje quirúrgico necesario para cada paciente. The surgical approach to different pathologies, not only oncological, has evolved. As Veronesi's group has coined very graphically, we are moving from "maximum tolerable treatments to minimum effective treatments" and this journey cannot be carried out in any other way than through a multidisciplinary and multimodality approach. Multidisciplinary, because collaboration between surgeons, oncologists, radiologists, nuclear physicians, pathologists, and all those involved in patient follow-up is necessary, and multimodality, because we must move towards precision surgery tailored to each patient in which, on the part of Nuclear Medicine, hybrid imaging (SPECT/CT and PET/CT), bimodal tracers, the use of new allies such as ultrasound or our own adaptation to robotic surgery have a great deal to say. A wide range of possibilities is built on the solid foundation of preoperative scintigraphy, which makes it possible to identify the target tissues and whose knowledge prior to surgery allows the necessary surgical approach to be considered for each patient. [ABSTRACT FROM AUTHOR]

The historical anthropogenic impact on sediments from the Basque Mud Patch (southern Bay of Biscay) is explored using a multidisciplinary approach including the analysis of natural (210Pb) and artificial (137Cs, 239/240Pu) radiotracers, major elements (Al, Mn), metals (Zn, Pb, Cu, Cr), Pb isotopic ratios, and foraminiferal and pollen contents. The study of three short cores (19–46 cm), despite being hindered by the effects of biomixing, allow the calculation of a sedimentation rate of 1 ± 0.1 mm yr−1. Distribution with depth of Al-normalised concentrations of metals reflects an increasing trend since 1880 CE, related to the industrialization of the Basque coastal area. According to the Sediment Quality Guidelines applied, contents of Zn and Pb appear as a potential cause of concern, given that they exceed the values from which adverse biological effects can be occasionally expected. However, foraminiferal assemblages do not show recognizable changes along the cores following increasing trace metal concentrations. Finally, pollen results reveal an increasing trend of coniferous taxa and a parallel reduction of authochthonous Deciduous Quercus , probably as a consequence of reforestation works. Data obtained confirm that effects of coastal anthropogenic activities extend to the adjacent shelf, where muddy deposits are likely to act as a trap for contaminants. [ABSTRACT FROM AUTHOR]

Focused ultrasound (FUS) is a minimally-invasive technology used for treatment of many diseases, including diseases related to the colon, uterus, prostate, and brain. Although it has been mainly used for ablative procedures, the ability of FUS to open the blood-brain barrier (BBB) presents a promising new application. However, the mechanism of BBB opening by FUS remains unclear. This review focuses on the use of FUS to open the BBB for enhancing drug delivery and investigating how Positron Emission Tomography (PET) provides insight into the underlying mechanism. Unlabelled Image • FUS may be a useful technique to enhance cerebral drug delivery. • The mechanism of BBB opening by FUS remains unclear. • The effect of FUS and microbubbles on the mechanism of BBB transporters remains undetermined. • PET may be a promising quantitative approach to assess the molecular effects of sonication. [ABSTRACT FROM AUTHOR]

In this study, the application of photoacoustic spectroscopy (FT-IR/PAS) is proposed to investigate membrane fouling phenomena. Ultrafiltration membranes made of polyether sulfone (PES) in modules operated at different flow regimes (dead-end and cross-flow) were used in this paper. Solutions of water-soluble poly(acrylic acid) and suspensions of a natural red clay were used as model media during the filtration tests. The research performed involved the possibility of tracking the in-situ rate of membrane fouling during filtration of these two types of media. Moreover, the influence of the molecular weight of the separated particles on the intensity of the membrane blocking was studied. The results of the experiments showed that fouling phenomena progress for various types of media filtrated is characterized by different particle sizes and can be simply detected using photoacoustic spectroscopy. It was also noted that an increase in the molecular weight of the filtrated medium, e.g., poly(acrylic acid) from 30 to 250 kDa, increased the intensity of membrane blocking of 57 and 87% for membrane installation with dead-end and cross-flow regime, respectively. The performed studies demonstrated that FT-IR/PAS can be also used to assess the efficiency of the methods used for membrane cleaning. The obtained results were confirmed by two other methods: a radiotracer technique and scanning electron microscopy. Image 1 • Photoacoustic spectroscopy was applied to study the rate of membrane fouling. • The impact of molecular weight of PAA on the intensity of membrane fouling was analysed. • Changes in the quantity of deposits formed on the membrane were measured using the PAS method. • Results were confirmed by the radiometric method and SEM analysis. [ABSTRACT FROM AUTHOR]

68Ga-labeled cyclic RGD dimers and trimer were evaluated as PET radiotracers. It was found that the linker group had little impact on α v β 3 binding affinity of RGD dimers, which share similar α v β 3 binding affinity with the RGD trimer despite of their different multiplicity. Biodistribution properties of 68Ga radiotracers depend on RGD peptides and radiometal chelates. Among the 68Ga radiotracers evaluated, 68Ga-I2P-RGD 2 has the best tumor uptake with good tumor-to-background ratios, and is a good PET radiotracer for imaging gliomas. • Three new 68Ga radiotracers were prepared and evaluated as radiotracers for glioma imaging. • NOTA-Galacto-RGD 2 , NOTA-I2P-RGD 2 and NOTA-4P-RGD 3 share similar α v β 3 binding affinity. • 68Ga-I2P-RGD 2 has higher tumor uptake than 68Ga-Galacto-RGD 2 and 68Ga-4P-RGD 3. • The blocking experiment shows that the tumor uptake of 68Ga radiotracers is α v β 3 –specific. [ABSTRACT FROM AUTHOR]

Abstract Plastic pollution is ubiquitous in aquatic environments and its potential impacts to wildlife and humans present a growing global concern. Despite recent efforts in understanding environmental impacts associated with plastic pollution, considerable uncertainties still exist regarding the true risks of nano- and micro-sized plastics (<5 mm). The challenges faced in this field largely relate to the methodological and analytical limitations associated with studying plastic debris at low (environmentally relevant) concentrations. The present paper highlights how radiotracing techniques that are commonly applied to trace the fate and behaviour of chemicals and particles in various systems, can contribute towards addressing several important and outstanding questions in environmental plastic pollution research. Specifically, we discuss the use of radiolabeled microplastics and/or chemicals for 1) determining sorption/desorption kinetics of a range of contaminants to different types of plastics under varying conditions, 2) understanding the influence of microplastics on contaminant and nutrient bioaccumulation in aquatic organisms, and 3) assessing biokinetics, biodistribution, trophic transfer and potential biological impacts of microplastic at realistic concentrations. Radiotracer techniques are uniquely suited for this research because of their sensitivity, accuracy and capacity to measure relevant parameters over time. Obtaining precise and timely information on the fate of plastic particles and co-contaminants in wildlife has widespread applications towards effective monitoring programmes and environmental management strategies. Highlights • Global plastic pollution poses potential risks to aquatic wildlife and humans. • Several fundamental research questions remain to be addressed in this field. • Radiotracer techniques are highly sensitive and capable of real-time analysis in vivo. • We outline how radiotracers can contribute towards environmental plastics research. • Radiolabeled microplastics and chemicals can benefit bioaccumulation and contaminant transfer studies. [ABSTRACT FROM AUTHOR]

Radioactive Particle Tracking (RPT) is a fluid measurement technique used in opaque ducts. To initiate the gauging process, RPT always requires the calibration of detectors. However, calibration poses a challenge for RPT deployment in industries. In most cases, experimental measurements are not a feasible option to calibrate RPT systems. To overcome this issue, Monte-Carlo simulations have been developed to imitate detector behavior and information recording. This study aimed to develop a user-friendly GEANT4 application for non-programmers to implement RPT in pipes with rectangular and cylindrical shapes. Additionally, the study used the application to evaluate which radiation detector arrangement can provide the best information for reconstructing particle position based on an Exploratory Data Analysis and the performance of machine learning algorithms. Two types of trajectories were simulated using the SAS GEANT4 application: straight and helicoidal. The generated results were normalized according to the activity of the radioactive source. The K-Nearest Neighbors algorithm and the Feedforward Neural Network were used to reconstruct the particle position. The detector arrangements were evaluated using Mean Euclidean Distance Error and Mean Absolute Error for each axis. • SAS GEANT4-based application was built to simulate radioactive particle tracking. • Radioactive particle tracking system was calibrated with positions from trajectories. • K Nearest Neighbors Regressor can be used for rendering particle positions. [ABSTRACT FROM AUTHOR]

Neuroendocrine neoplasms are rare and heterogenous group of tumors with varying degrees of clinical presentations and involvement of multiple organ systems in the body. In the modern clinical practice somatostatin receptor molecular imaging and targeted radioligand therapy plays a vital role in the diagnosis and management of the disease. Several new and promising radiotracers for NET imaging and theranostics, belonging to various groups and classes are being studied and investigated. This exponential growth of radiotracers poses concerns about the indication, clinical benefit, and safety profile of the agents. We discuss the basis behind these radiotracers clinical use, receptor targeting and intra and inter tumor heterogeneity. Furthermore, role of dual tracer imaging, combination therapy and potential applications of dosimetry in predicting treatment outcome and safety profile is reviewed. Individualized precision medicine with better tumor characterization, maximum therapeutic benefit and minimum toxicity is the way forward for future medicine. [ABSTRACT FROM AUTHOR]

A novel, rapid, and automated loop method for the synthesis of [ 11 C]nicotine was developed and optimized. The method involves, a reaction of the precursor, ( + ) nornicotine or (-) nornicotine, with a gas-phase produced [ 11 C]CH 3 I in an 800 µL loop at 75 °C for 5 min followed by a semi-preparatory Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC) purification. The optimized synthesis and purification process was complete in < 30 min and produced [ 11 C]nicotine with > 99.9% Radiochemical Purity (RCP), no [ 11 C]CH 3 I, no ( + ) nornicotine, 105 mCi/µmole specific activity, 7.0 – 7.2 pH, and 16.6% ethanol. The current method can be optimized, to reduce the ethanol content (<10%), and can be translated to a cGMP production of [ 11 C]nicotine for human clinical trials. [ABSTRACT FROM AUTHOR]

Eckernförde Bay in the Baltic Sea is well-known for the pockmarks areas which are located in the centre and off the southern shore-line of the bay emanating groundwater in a non-continuous but episodic way. Mobile underwater in situ gamma-ray spectroscopy is exploited proving that both 214 Bi and 40 K are efficient radiotracers for localization of seepage areas whenever either sediment is in mixture with the emanating fluid or resuspension of surface sediment occurs as a side effect of the fluid emanation. [ABSTRACT FROM AUTHOR]

A series of novel thymidine dithiocarbamate derivatives (DTC-TdR) were successfully synthesized and then radiolabelled using [ 99m Tc(CO) 3 ] + core with high yields. The chemical characterizations of 99m Tc(CO) 3 -labelled dithiocarbamate derivatives have been carried out by preparing their corresponding rhenium complexes. The radiotracers were stable in vitro , and the partition coefficient results indicated that they were lipophilic. The cell uptake studies showed the uptakes of these 99m Tc(CO) 3 -labelled thymidine derivatives were mediated by nucleoside transporters. Biodistribution of the complexes in mice bearing tumor showed that they had high tumor uptake and good tumor/muscle ratio. A clear SPECT imaging of the tumor location was obtained in mice bearing S180 tumor with one of radiotracers, suggesting they would be potential tumor imaging agents. [ABSTRACT FROM AUTHOR]

Radioactive Particle Tracking (RPT) is a non-invasive measurement technique used to reconstruct the Lagrangian particle field inside a fluid flow. This technique tracks the trajectories followed by radioactive particles that move along the fluid, and it is based on the counts registered by radiation detectors that are placed strategically around the boundaries of the system. The aim of this paper is to develop a low-budget RPT system proposed by the Departamento de Ciencias Nucleares of the Escuela Politécnica Nacional and to generate a GEANT4 model of it for optimizing its design. This system is based on the usage of the minimum amount of radiation detectors required to track a tracer and on the innovative idea of calibrating them with moving particles. To achieve this, energy and efficiency calibrations were performed with a single NaI detector, and their results were compared with the results generated with a GEANT4 model simulation. As a result of this comparison, another methodology was proposed to add the effects of the electronic detector chain in the simulated results by a Detection Correction Factor (DCF) without further C++ coding in GEANT4. Next, the NaI detector was calibrated for moving particles. For this purpose, a single NaI was used in different experiments to analyze the influence of particle velocity, data acquisition systems, and radiation detector position along the x-axis, y-axis, and z-axis. Finally, these experiments were simulated in GEANT4 to improve the digital models. Particle positions were reconstructed based on the generation of Trajectory Spectrum (TS) which gives a specific count rate for each particle position as it moves on the x-axis. The magnitude and shape of TS were compared with DCF corrected simulated data and experimental results. This comparison showed that the variation of detector position along the x-axis changed the shape of TS, while the variation of the location along the y-axis and z-axis reduced the sensitivity of the detector. The existence of an effective zone of the detector location was identified. At this zone, the TS shows high changes in the count rate for low changes of particle position. Based on the overhead of the TS, it was demonstrated that this RPT system must employ at least 3 detectors to have capabilities to predict particle positions. • Trajectory Spectra are used to predict particle position in a proposed RPT system. • Trajectory Spectra have flat and effective zones that can be used to track a particle. • An RPT system needs several detectors to have redundant information. • Reducing the detector number is one feasible way to make low-cost RPT systems. [ABSTRACT FROM AUTHOR]

A series of vasopressin receptor V 1a ligands have been synthesized for positron emission tomography (PET) imaging. The lead compound (1 S, 5 R )- 1 ( (4-(1H-indol-3-yl)-3-methoxyphenyl) ((1 S ,5R)-1,3,3-trimethyl-6-azabicyclo[3.2.1]octan-6-yl)methanone ) and its F-ethyl analog 6c exhibited the best combination of high binding affinity and optimal lipophilicity within the series. (1 S, 5 R )- 1 was radiolabeled with 11 C for PET studies. [ 11 CH 3 ](1 S, 5 R )- 1 readily entered the mouse (4.7% ID/g tissue) and prairie vole brains (∼2% ID/g tissue) and specifically (30–34%) labeled V 1a receptor. The common animal anesthetic Propofol significantly blocked the brain uptake of [ 11 CH 3 ](1 S, 5 R )- 1 in the mouse brain, whereas anesthetics Ketamine and Saffan increased the uptake variability. Future PET imaging studies with V 1a radiotracers in non-human primates should be performed in awake animals or using anesthetics that do not affect the V 1a receptor. [ABSTRACT FROM AUTHOR]

Bubble column reactors are widely used for gas-liquid operations and most often are fitted with vertical internals for appropriate heat transfer. Apart from these applications, cylindrical vessels with concentrically installed vertical tube bundles find major use in boiling water reactors. Most often, heat removal takes place in boiling water reactors by phase change of the flowing water, which results in a complex, axially developing and highly dynamic two-phase flow pattern. Though the hydrodynamics in a bubble column with vertical internals have been addressed in few publications, the characteristics of liquid phase mixing and turbulence over a wide range of operating conditions and dense configuration of the internals have not been reported thus far. The present communication addresses the hydrodynamic characteristics in bubble column equipped with dense internals over a wide range of superficial gas and liquid velocities. Experiments were performed using the air-water system in a 120 mm I.D. bubble column with, and without internals, by varying the percent cross-sectional area covered by the internals. A non-invasive Radioactive Particle Tracking (RPT) method has been employed for estimating the hydrodynamic parameters and mixing characteristics have also been investigated using residence time distribution (RTD) studies with radiotracers. The experimental results obtained in this work indicates that the configuration of the heat exchanger internals, superficial gas, and liquid velocities have a strong effect on liquid phase hydrodynamics and mixing characteristics. [ABSTRACT FROM AUTHOR]

Introduction The production of 18 F-radiotracers using continuous flow microfluidics is under-utilized due to perceived equipment limitations. We describe the dose-on-demand principle, whereby the back-to-back production of multiple, diverse 18 F-radiotracers can be prepared on the same day, on the same microfluidic system using the same batch of [ 18 F]fluoride, the same microreactor, the same HPLC column and SPE cartridge to obtain a useful production yield. Methods [ 18 F]MEL050, [ 18 F]Fallypride and [ 18 F]PBR111 were radiolabeled with [ 18 F]fluoride using the Advion NanoTek Microfluidic Synthesis System. The outlet of the microreactor was connected to an automated HPLC injector and following the collection of the product, SPE reformulation produced the 18 F-radiotracer in <10% ethanolic saline. A thorough automated cleaning procedure was implemented to ensure no cross-contamination between radiotracer synthesis. Results The complete productions for [ 18 F]MEL050 and [ 18 F]Fallypride were performed at total flow rates of 20 μL/min, resulting in 40 ± 13% and 25 ± 13% RCY respectively. [ 18 F]PBR111 was performed at 200 μL/min to obtain 27 ± 8% RCY. Molar activities for each 18 F-radiotracer were >100 GBq/μmol and radiochemical purities were >97%, implying that the cleaning procedure was effective. Conclusions Using the same initial solution of [ 18 F]fluoride, microreactor, HPLC column and SPE cartridge, three diverse 18 F-radiotracers could be produced in yields sufficient for preclinical studies in a back-to-back fashion using a microfluidic system with no detectable cross-contamination. [ABSTRACT FROM AUTHOR]

Deltaic floodplains are thought to be long-term depositional environments, however there remains a limited understanding regarding timescales of depositional and erosional events, sediment delivery pathways and sediment storage. This study uses sediment concentration and sediment fingerprinting to examine the contribution of surface and subsurface sources to suspended sediment transiting the Lower Roanoke River, North Carolina, United States. The Lower Roanoke is disconnected from its high-gradient uplands in the Piedmont and Appalachian Mountains by a series of dams, which effectively restricts suspended sediment delivery from the headwaters. Accordingly, sediments from the Lower Roanoke River basin are the primary source of suspended sediment downstream of the dams. The fingerprinting method utilized fallout radionuclide tracers ( 210 Pb xs and 137 Cs) to examine the spatial variation of sediment-source contributions to suspended-sediment samples ( n = 79). Three end-member sources were sampled: 1. surface sources (floodplains and topsoils; n = 60), 2. subsurface sources (channel bed and banks; n = 66), and 3. deltaic sources (delta front and prodelta; n = 11). The results demonstrate that with decreasing river slope and increasing influence of estuarine-driven flow dynamics, the relative contribution of surface sediments to the suspended-sediment load increases from 20% (± 2%) in the upper reach, to 67% (± 1%) in the Roanoke bayhead delta (BHD). At the river mouth, the surface-sediment contribution decreases, and the delta front and prodelta sediments contribute 74% (± 1%) to the suspended load. These results indicate, that during the delta transgression, erosion of the lower delta provides an additional source of sediment to the upper delta. At the same time, the lower deltaic plain, considered a sediment sink and long-term sediment-storage site, becomes erosional. The lower river and distributary network of the delta plain, which were thought to only disperse sediments in a seaward direction, may also have an important landward-directed sediment-dispersal component that provides nourishment and fortification to the upper BHD, at the cost of the eroding lower delta. Recognition of these contrasting sediment pathways in the Roanoke River highlights that these complex bidirectional processes may exist in other eroding deltas. Understanding these bidirectional processes will be necessary for the ongoing management of deltaic environments under increasing anthropogenic stress such as land use change and accelerating sea-level rise. [ABSTRACT FROM AUTHOR]

In last years, sensitive hydrogels have become a breakthrough in ophthalmic pharmaceutical technology aimed at developing new strategies to increase the residence time of active substances. In a previous paper, we qualitatively demonstrated the capacity of a new ion sensitive hydrogel to increase the residence time. Nevertheless, the clearance of the gel from the ocular surface was not quantifiable with the used methodology. The aim of the present work was to use a well-established approach based on scintigraphy to quantitatively estimate the residence time of the previously proposed hydrogel. The rat corneal residence time of a topic ophthalmic formulation containing gellan gum and kappa carragenan (0.82% w/v) labeled with 99mTc-DTPA radiotracer was evaluated and compared with the residence of an aqueous solution. Ophthalmic safety studies such as eye irritation or passage through the cornea were also carried out. After 1.5 h of contact, 77% of the hydrogel remained in the ocular surface, presenting kinetics of disappearance one-phase decay and a half time of 262 min. We conclude that the novel ophthalmic hydrogel developed with kappa carrageenan and gellan gum remains for long periods of time on the corneal surface, presenting a drop that fits an exponential decay. [ABSTRACT FROM AUTHOR]

Focal adhesion kinase (FAK) is considered as an attractive target for oncology. A series of F-18 labeled 5-bromo-N 2 -(4-(2-fluoro-pegylated (FPEG))-3,5-dimethoxyphenyl)-N 4 -(4-methoxyphenyl)pyrimidine-2,4-diamine derivatives were prepared and evaluated as the FAK targeted radiotracers for the early diagnoses of tumor. For the study of the FAK targeted drug molecules, this was the first attempt to develop the tumor diagnostic imaging agents on the radiopharmaceutical level. They inhibited the activity of FAK with IC 50 in the range of 91.4–425.7 nM, and among which the result of the [ 19 F] 2 was relatively good and had a modest IC 50 of 91.4 nM. The [ 19 F] 2 was also profiled in vitro against some other kinds of cancer-related kinases (including two kinds of non-receptor tyrosine kinase: PYK2 and JAK2, and three kinds of receptor tyrosine kinase: IGF-1R, EGFR and PDGFRβ). It displayed 25.2 folds selectivity against PYK2, 35.1 folds selectivity against EGFR, and more than 100 folds selectivity against IGF-1R, JAK2 and PDGFRβ. For the biodistribution in S180 bearing mice, the corresponding [ 18 F] 2 were also relatively good, with modest tumor uptake of 5.47 ± 0.19 and 5.80 ± 0.06 %ID/g at 15 and 30 min post-injection, respectively. Furthermore, its tumor/muscle, tumor/bone and tumor/blood ratio at 15 min post-injection were 3.16, 2.53 and 4.52, respectively. And its tumor/muscle, tumor/bone and tumor/blood ratio at 30 min post-injection were 3.14, 2.76 and 4.43, respectively. In addition, coronal micro-PET/CT images of a mouse bearing S180 tumor clearly confirmed that [ 18 F] 2 could be accumulated in tumor, especially at 30 min post-injection. Besides, for the [ 18 F] 2 , both the biodistribution data and the micro-PET/CT imaging study showed significantly reduced uptake of the radiotracer in the tumor tissue at 30 min post-injection in mice that received PF-562,271 (one of the reported best selective FAK inhibitor which was developed by Pfitzer Inc. and inhibited the activity of FAK with IC 50 value of 1.5 nM) at 1 h before the injection of radiotracer. In combination with the above kinase profiling assay, it could be indicated that the uptake of [ 18 F] 2 in tumor of the mouse model was due to FAK expression, and that [ 18 F] 2 might be a kind of selectively FAK targeted tumor imaging agents. What's more, the results of the MD (molecular dynamics) simulations were in agreement with the changing trends of the interaction between the different F-19 standards and the FAK (expressed as the in vitro inhibitory abilities of enzymatic activities of FAK in this article), which was also in agreement with and had great effect on the changing trends of the uptake of the corresponding F-18 labeled tracers in tumor and some of theirs target/non-target ratios. [ABSTRACT FROM AUTHOR]

Numerous field studies highlighted the capacities of marine sponges to bioaccumulate trace elements and assessed their potential as biomonitors of the marine environment. Experimental works demonstrated that dissolved metals and radionuclides can be taken up directly by sponge tissues but, to the best of our knowledge, little is known on the contribution of the dietary pathway through the consumption of contaminated bacteria considered as one of the trophic source in sponge diet. Objectives of this work are to study trophic transfer of radiotracers 110m Ag, 241 Am, 109 Cd, 57 Co, 134 Cs, 54 Mn and 65 Zn from the marine bacteria Pseudomonas stutzeri to the Mediterranean sponges Aplysina cavernicola and Ircinia oros. P. stutzeri efficiently bioaccumulated trace elements in our culture experimental conditions with CF comprised between 10 5 and 10 7 after 48 h of growth in radiolabeled medium. When fed with these radiolabelled bacteria, A. cavernicola took up around 60% of radiotracers accumulated in trophic source except 134 Cs for which only 8% has been transferred from bacteria to sponge. Contrasting to this, I. oros retained only 7% of 110m Ag, 109 Cd and 65 Zn counted in bacteria, but retained 2-fold longer accumulated metals in its tissues. The sponge inter-specific differences of accumulation and depuration following a trophic exposure are discussed with respect to the structure and the clearance capacities of each species. [ABSTRACT FROM AUTHOR]

Reworked muds, including mobile muds, resuspended sediments, and bio-mixed muds are ephemeral layers in the benthic boundary of large-river delta-front estuaries (LDEs). In this study, multiple radiotracers ( 210 Pb, 137 Cs, 234 Th, 7 Be, 235 U, 228 Th, 228 Ra, 226 Ra and 40 K) were combined to evaluate the sedimentary dynamics of the mud belt on the inner shelf of the East China Sea (ECS) adjacent to the Changjiang River Estuary. We first categorized eight types of typical 210 Pb profiles in marine sediments, and specified which ones could be used as possible evidence of reworked muds. The types of 210 Pb profiles observed in previous studies and this study were then used to examine the depth distribution of reworked mud layers of the benthic boundary of ECS. We found that reworked mud depth in the along-shore mud belt of the inner shelf of ECS was deeper than those in the outer shelf and slope area, reaching up to 150 cm deep in the Changjiang River LDE, and up to 50 cm deep in the Zhejiang–Fujian coast mud area. Sediment core tracer profiles also showed that the reworked mud layer could be further divided into several sub-layers with distinct redox conditions and microbe (sulfate-reducing bacterial) abundance. SRB abundance intensively fluctuated with changing redox environment, and larger abundance values were usually observed in anoxic conditions. Based on 7 Be and 234 Th, the top layer (ca. 2–4 cm thick) was the most modern and active zone, showing evidence of reworking on seasonal timescales. The deeper sections of the reworked mud layer were generally modified over longer timescale (years) which were examined using the more long-lived tracers, e.g., 137 Cs, 228 Th ex , and 228 Ra/ 226 Ra ratio. We found for the first time in this region that age of the reworked layers was usually much younger than underlying accumulating (burial) layers. We posit that this multi-radionuclide approach is critical for evaluating the complex biogeochemical sediment record on delta-front estuaries of large rivers subject to changing climate conditions and human impacts over the last several centuries. [ABSTRACT FROM AUTHOR]

This research is focused on studying the preferred source regions and the pathways of the air masses with high particulate concentrations impacting on the activity concentrations of 7Be and 210Pb aerosols in Granada atmosphere. For this purpose, three different source-receptor methods have been used: Cluster Analysis, Potential Source Contribution Function (PSCF), and Concentration Weighted Trajectory (CWT). Air filter samples were weekly collected and analysed in Granada university (Spain 37.177N, 3.598 W, 687m a.s.l.) during 12 years (2006–2017) for the activity concentration of 7Be, and during 5 years (2010–2014) for the one of 210Pb. The time series of the collected data indicate that the concentration of both radiotracers present a cyclical and seasonal pattern, in association with their origins and atmospheric conditions. Clustering analysis showed that the air masses arriving to Granada can be classified as: (1) tropical continental air masses coming from the Mediterranean Sea, (2) tropical and warm polar maritime air masses produced over the Atlantic Ocean, and (3) continental air masses originated over Europe and Northern Africa. The PSCF and CWT methods confirmed that the main source areas of 7Be are located in the Atlantic coast of southern Morocco, and Northern Africa. On the other hand, southern France and the Algerian desert were found to be the main region sources of 210Pb. In addition, the Mediterranean Basin has been postulated as a strong source region for 7Be and 210Pb. Furthermore, the PSCF and CWT models show that the regions with larger 7Be/210Pb ratios are located in the Atlantic Ocean, due to frequent stratospheric intrusions specially during the winter months. • A seasonal pattern of 7Be and 210Pb was identified in Granada, Spain. • Back trajectory analysis was used to identify the origin and pathway of air masses. • Potential sources regions of 7Be and 210Pb activity were investigated. • Granada is affected by Mediterranean Sea, Atlantic Ocean, and Sahara. • Mediterranean basin is the main source common of 210Pb and 7Be. [ABSTRACT FROM AUTHOR]

The isotopic ratio of two cosmogenic isotopes, 22Na and 7Be, has been recognized as a possible tracer for atmospheric dynamics. We studied how different atmospheric phenomena affect the 22Na/7Be ratio that are known to affect the ground level 7Be concentrations. The 22Na/7Be ratio was studied in the following context: estimation of aerosol residence time, in the intrusions of stratospheric air after Sudden Stratospheric Warming (SSW) events, seasonal variations due to different atmospheric mixing conditions and finally the interannual variations caused by the large-scale atmospheric circulation such as North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Scandinavian Pattern (SCAND) and Quasi-Biennial Oscillation (QBO). This study utilized airborne radioactivity monitoring data from three Finnish stations located in Rovaniemi (66.51 °N, 25.73 °E), Kajaani (64.08 °N, 27.71 °E) and Kotka (60.48 °N, 26.92 °E). The theoretical calculations were performed to see how the 22Na/7Be ratio changes as a function of altitude during when produced by the galactic cosmic rays. The calculations showed that the 22Na/7Be ratio is higher in the stratosphere and lower in the troposphere. At mid-stratosphere level the ratio was 0.001, at tropopause level approximately 0.0007 and at ground level approximately 0.00045. Due to the different half-lives of 22Na and 7Be the mean atmospheric residence time can be estimefrom the radioactive decay law by assuming an initial activity concentration ratio of 0.0007 and using the measured ground level 22Na/7Be ratios. This resulted in the median atmospheric residence time as 91–95 days. The atmospheric impact on 22Na/7Be ratio was studied at different time scales starting from short-term impact from SSW, the known seasonal cycle and variations at interannual timescale. SSW events caused rapid increases in the ground level 7Be and 22Na concentrations while the impact on 22Na/7Be ratio was relatively small. A clear seasonal cycle in the 22Na/7Be ratio was observed where the 22Na/7Be ratio was at low value during November–February, increased during March–May, stayed at stable high value during June–July and steadily decreased during August–October. The long-term average for 22Na/7Be ratio was established to be 1.1 × 10−4 by using the Kotka data from 1993 to 2020. During 1995–2009, the 22Na/7Be ratio was below the long-term average, and during 2010–2020, generally above. The interannual variations in the 22Na/7Be ratio were studied by using wavelet transform analysis of the Kotka data. The analysis showed 4-6-year and 11-year periodicities. The wavelet coherence analyses with AO, NAO, SCAND, QBO and Southern Oscillation (SO) indices showed that the shorter periodicity was caused by the NAO/AO effects the atmospheric circulation in Scandinavia and hence the transport of the isotopes from upper atmosphere to ground level. The observed coherence with the Southern Oscillation Index (SOI) starting from 2012 onwards appeared at an approximately 3–4year scale while the AO and NAO had a coherence at an approximately 6-year scale. The observed 11-year periodicity was caused by the Solar cycle which modulates the 7Be and 22Na production in the upper atmosphere. • The mean transport time for 7Be and 22Na was estimated as 91–95 days. • SSW events affected the 7Be and 22Na concentrations but less the 22Na/7Be ratio. • The 22Na/7Be seasonal cycle was established at weekly level. • The long term 22Na/7Be annual average was determined as 1.19 × 10−4. • NAO/AO, SOI and the Solar cycle modulated 22Na/7Be at interannual level. [ABSTRACT FROM AUTHOR]

The relationship between the particulate matter in the atmosphere of Malaga and the origin of air masses with special attention to African intrusions was analyzed. The concentrations of PM10 and the activities of some radionuclides ( 7 Be and 210 Pb) as tracers of these intrusions are discussed. The origin of these radiotracers is completely different. 210 Pb is a good tracer of air masses traveling close to the ground and come from inland areas. On the other hand, the production of 7 Be is very low in the vicinity of the Earth's surface, and increases with altitude, making it a great tracer of stratospheric air masses in the troposphere. Studies of radionuclide activities in aerosol particles provide a means for evaluating the integrated effects of transport and meteorology on the atmospheric loadings of substances with different sources. Measurements of aerosol mass concentration and specific activities of 7 Be and 210 Pb in aerosols at Malaga (36° 43′ 40″ N; 4° 28′ 8″ W) for the period 2009–2011 were used to obtain the relationships between radionuclide activities and airflow patterns by comparing the data grouped by air mass trajectory. The average concentration values of 7 Be and 210 Pb over the 3-year period have been found to be 5.05 and 0.55 mBq m −3 , respectively, with mean aerosol mass concentration of 53.6 μg m −3 . Taking into account the outbreaks of the daily values limits of PM10 in the study period (2009–2011), the origin of air masses is studied to explain three different situations of both radionuclides 7 Be and 210 Pb: 1) high concentrations of 7 Be and low concentrations of 210 Pb; 2) high concentrations of 210 Pb and low concentrations of 7 Be and 3) high concentrations of 7 Be and 210 Pb. [ABSTRACT FROM AUTHOR]

Detonation nanodiamonds (NDs) are considered to be potential carriers in drug delivery platforms because of their low cytotoxicity (4–5 nm particles), biocompatibility, highly developed surface area, chemically inert core and intrinsically hydrophilic surface. The adsorption/desorption processes of physiologically active compounds on ND surfaces play an important role in drug design. The electrostatic attraction between ND surface groups and the functional groups of adsorbates is the most commonly described mechanism of the adsorption process. However, the role of hydrophobic interactions has not yet been described. Here, we show that a positively charged antiseptic agent (Myramistin®) binds to a ND possessing a positive zeta potential via hydrophobic interactions between the hydrocarbon fragment of Myramistin and graphitic carbon of the ND surface. To achieve a reliable determination of low values of adsorption, a radioactive label was introduced into Myramistin molecules. Tritium was used as a labeling agent and it was introduced into Myramistin by means of tritium thermal activation method. The obtained value of the binding strength indicates easy drug release, as confirmed by in vitro release studies. We anticipate that our assay and the results obtained to be a starting point for more sophisticated models of drug adsorption/desorption processes of nanodiamond drug delivery platforms. [ABSTRACT FROM AUTHOR]

Biodynamic modeling was used to investigate the uptake and bioaccumulation of arsenic and silver from water and food by two Hydropsychid caddisfly larvae: Hydropsyche siltalai and Hydropsyche pellucidula . Radiotracer techniques determined the uptake rate constants of arsenic and silver from water, and assimilation efficiencies from food, and their subsequent loss rate constants after accumulation from either route. The uptake rate constants (±SE) of As and Ag from solution were 0.021 ± 0.005 and 0.350 ± 0.049 L g −1 day −1 , respectively, for H. siltalai , and 0.435 ± 0.054 and 0.277 ± 0.021 L g −1 day −1 , respectively, for H. pellucidula in moderately hard synthetic water at 10 °C. The assimilation efficiencies (±SE) of As and Ag from radiolabeled ingested food were 46.0 ± 7.7% and 75.7 ± 3.6%, respectively, for H. siltalai , and 61.0 ± 4.2% and 52.6 ± 8.6%, respectively, for H. pellucidula . Ag, but not As, AEs were significantly different between species. The AE of Ag differed from the AE of As in H. siltalai , but not in H. pellucidula . Mean efflux rate constants after accumulation of metals from solution or food ranged from 0.039 to 0.190 day −1 . The efflux rate constants of As and Ag accumulated from solution were significantly lower than those of As and Ag assimilated from ingested food in both species. Experimentally derived k u and k e values were then used to predict As and Ag tissue concentrations in hydropsychids collected from 13 UK sites, including metal-contaminated streams in Cornwall. Arsenic and silver concentrations in environmental water and food (suspended particles) samples were measured. Biodynamic models successfully predicted accumulated As and Ag concentrations in resident H. siltalai and H. pellucidula at each site. The models also showed that more than 95% of accumulated As and almost 100% of accumulated Ag in H. siltalai and H. pellucidula are derived from ingested food rather than from water. [ABSTRACT FROM AUTHOR]

Introduction In this study two 111 In-labeled dimeric cyclic RGD peptides, 111 In(DOTA-Galacto-RGD 2 ) and 111 In(DOTA-3P-RGD 2 ), were evaluated as radiotracers for breast tumor imaging. The objective was to evaluate the impact of SAA, PEG 2 and 1,2,3-triazole linkers as compare to PEG 4 on the tumor uptake and excretion kinetics of 111 In radiotracers. Methods DOTA-Galacto-RGD 2 was prepared by conjugation of Galacto-RGD 2 with DOTA-OSu in the presence of diisopropylethylamine. Its integrin α v β 3 binding affinity was determined using a whole-cell displacement assay against 125 I-echistatin bound to U87MG glioma cells, and was compared with those of c(RGDfK), DOTA-3P-RGD 2 and DOTA-3P-RGK 2 (a nonsense peptide conjugate with “scrambled” RGK sequences). 111 In(DOTA-Galacto-RGD 2 ) and 111 In(DOTA-3P-RGD 2 ) were prepared and evaluated for their tumor-targeting capability and biodistribution properties in athymic nude mice bearing MDA-MB-435 breast tumor xenografts. Planar imaging studies were performed to demonstrate the utility of 111 In(DOTA-Galacto-RGD 2 ) and 111 In(DOTA-3P-RGD 2 ) for breast tumor imaging. Results IC 50 values of DOTA-Galacto-RGD 2 , DOTA-3P-RGD 2 , and DOTA-3P-RGK 2 were calculated to be 27 ± 2, 29 ± 4, 596 ± 48 nM, respectively. The tumor uptake values of 111 In(DOTA-Galacto-RGD 2 ) (6.79 ± 0.98, 6.56 ± 0.56, 4.17 ± 0.61 and 1.09 ± 0.13 %ID/g at 1, 4, 24 and 72 hours p.i., respectively) were almost identical to those of 111 In(DOTA-3P-RGD 2 ) (6.17 ± 1.65, 5.94 ± 0.84, 3.40 ± 0.50 and 0.99 ± 0.20 %ID/g, respectively). 111 In(DOTA-Galacto-RGD 2 ) had a faster clearance from blood and muscle than 111 In(DOTA-3P-RGD 2 ), leading to higher tumor/blood and tumor/muscle ratios. 111 In(DOTA-3P-RGD 2 ) had lower liver uptake and better tumor/liver ratios than 111 In(DOTA-Galacto-RGD 2 ). The tumor uptake of 111 In(DOTA-Galacto-RGD 2 ) and 111 In(DOTA-3P-RGD 2 ) was both integrin α v β 3 and RGD-specific. Imaging data suggest that 111 In(DOTA-Galacto-RGD 2 ) and 111 In(DOTA-3P-RGD 2 ) are useful as radiotracers for imaging integrin α v β 3 -positive breast tumors. Conclusion The results from this study suggest that replacing PEG 4 linkers between two RGD moieties with a pair of SAA, PEG 2 and 1,2,3-triazole groups has little impact on integrin α v β 3 binding affinity and tumor uptake of 111 In-labeled dimeric cyclic RGD peptides. Despite the subtle differences in their excretion kinetics from noncancerous tissues, 111 In(DOTA-Galacto-RGD 2 ) and 111 In(DOTA-3P-RGD 2 ) are useful radiotracers for imaging integrin α v β 3 -positive breast tumors. [ABSTRACT FROM AUTHOR]

This paper presents a study on the fouling of ceramic microfiltration (MF) membrane. Such membranes are often used in the treatment of liquid radioactive waste. In the investigation of the phenomenon of fouling, a radiotracer method with a short-lived lanthanum isotope (140La) is applied. The effect of the molecular weight (MW) of the complexing agent, used to bind the radionuclides in the MF-enhanced process, was studied in radiotracer experiments. Poly(acrylic acid) with a MW of 30 kDa, 100 kDa and 250 kDa is used as the complexing agent. The distribution of particles with different MWs at various positions along the membrane module is examined. The test results show that the particles with the lowest MW (i.e. 30 kDa) blocks the membranes the quickest, causing the greatest decrease in the permeate flux. However, the amount of deposit formed on the membrane, which is reflected by the level of radioactivity measured, is the lowest in this case. This indicates the existence of different membrane blocking mechanisms, which depend on the size of the particles contained in the filtered medium. [Display omitted] • Fouling of membranes used for LRW treatment was studied by the radiotracer method. • The polyacrylic acid (PAA) with different MWs was used as a model fouling agent. • The effect of MW of PAA on particles distribution along the membrane was examined. • The PAA molecules with the lowest MW blocked the membrane surface the fastest. • Different mechanisms of fouling can occur depending on the MW of PAA. [ABSTRACT FROM AUTHOR]

Abstract: An approach to estimate the rate of biogenic sedimentation in the Black Sea using the naturally occurring radionuclide 40K has been considered. It allows assessment of the contribution of suspended matter of biological origin to the overall sediment accumulation in the Black Sea coastal, shelf and deep-water areas. Based upon this method, a relationship between the biogenic fraction of the seabed sediments and the water depth has been established with a view to differentiating the contributions of allochthonous and autochthonous suspended matter to the sedimentation rate. Overall, 40K can be considered as an easily applicable proxy to assess sedimentation rate of biogenic fraction of particulate matter in marine environments. [Copyright &y& Elsevier]

Abstract: In Nuclear Medicine, radioiodine, in various chemical forms, is a key tracer used in diagnostic practices and/or therapy. Medical professionals may incorporate radioactive iodine during the preparation of the dose to be administered to the patient. In radioactive iodine therapy doses ranging from 3.7 to 7.4GBq per patient are employed. Thus, aiming at reducing the risk of occupational contamination, we developed a low cost filter to be installed at the exit of the exhaust system (where doses of radioiodine are handled within fume hoods, and new filters will be installed at their exit), using domestic technology. The effectiveness of radioactive iodine retention by silver impregnated silica [10%] crystals and natural activated carbon was verified using radiotracer techniques. The results showed that natural activated carbon and silver impregnated silica are effective for I2 capture with large or small amounts of substrate but the use of activated carbon is restricted due to its low flash point (423K). Besides, when poisoned by organic solvents, this flash point may become lower, causing explosions if absorbing large amounts of nitrates. To hold the CH3I gas, it was necessary to use natural activated carbon since it was not absorbed by SiO2+Ag crystals. We concluded that, for an exhaust flow range of (145±2)m3/h, a double stage filter using SiO2+Ag in the first stage and natural activated carbon in the second stage is sufficient to meet radiological safety requirements. [Copyright &y& Elsevier]

Abstract: Breast cancer is a heterogenic cancer being characterized by a variability of somatic mutations and in particular by different receptor expressions, such as estrogen, progesterone and human epidermal receptor. These phenotype characteristics play a crucial role in determining tumour response to various chemotherapies and other treatments and in the development of resistance to therapies. Positron emission tomography (PET) as a nuclear medicine technique, has recently demonstrated the advantages in determining the severity of disease and in evaluating the efficacy of treatments in a variety of neoplasm, including breast cancer. Because this procedure is able to pinpoint molecular activity within the body, it offers the potential to identify disease in its earliest stages as well as a patient’s immediate response to therapeutic interventions in a non-invasive way. In this paper we performed an extended view about the correlation between molecular factors of breast cancer and PET tracers; in particular, we focalized our attention on their possible advantages in terms of 1) early detection of primary or recurrent cancer; 2) as a guide for target therapies and 3) for the evaluation of response to specific and now-available molecular treatments. [Copyright &y& Elsevier]

Abstract: The analysis of radiotracers is important in the study of oil reservoir dynamics. One of the most widely used radiotracer is S14CN−. Prior to activity measurements by Liquid Scintillation (LS), routine determinations require the pretreatment steps of purification and concentration of the samples using anion exchange columns. The final elution media produces samples with high salt concentration that may lead to problems with phase separation during the LS measurement. Plastic Scintillation (PS) is an alternative technique that provides a solid surface that can be used as a platform for the immobilisation of selective extractants to obtain a PS resin. The proposed procedure unifies chemical separation and sample measurement preparation in a single step, serving to reduce the number of reagents needed and manpower required for the analysis while also avoiding mixed waste production by LS. The objective of this study is to develop a PS resin for the determination of 14C-labelled thiocyanate radiotracer in water samples. For this purpose, the immobilisation procedure was optimised, including optimisation of the proportion of PS microspheres:extractant and the use of a control blank to monitor the PS resin immobilisation process. The breakthrough volume was studied and the detection and quantification limits for 100mL of sample were determined to be 0.08BqL−1 and 0.31BqL−1, respectively. The established procedure was applied to active samples from oil reservoirs and errors lower than 5% in the sample determinations were obtained. [Copyright &y& Elsevier]

Abstract: The possibility of application of fluorescein and radioactive 99mTc as tracers for determination of residence time distribution of liquid phase and for diagnosing hydrodynamic conditions in apparatuses for membrane separation was studied. Two different ultrafiltration systems with diverse arrangement of liquid flow: the apparatus with helical flow generated by the movable element (inner cylinder) and the tubular module with cross flow filtration, were tested by the RTD technique. The tracer studies were supplemented with modelling. The optimal conditions enabling to handle the plug flow-like structure in the helical apparatus were determined. The minimum of dimensionless variance (vard) was obtained at P=0.765bar, Q R =121.88l/h and Ω=2887.5rpm. In spite of higher linear velocities attained in the tubular cross-flow module, the flow structure in the helical apparatus was more similar to the ideal plug flow pattern that was demonstrated by higher Peclet numbers and lower values of the dimensionless variance. Application of movable part and Couette–Taylor flow in the membrane apparatus may balance the advantages coming from high flow rates applied in cross-flow filtration systems minimising formation of the deposit on the membrane surface and reducing membrane fouling. [Copyright &y& Elsevier]

Abstract: Small-scale gold mining in Portovelo–Zaruma, Southern Equador, performed by mercury amalgamation and cyanidation, yields 9–10t of gold/annum, resulting in annual releases of around 0.65t of inorganic mercury and 6000t of sodium cyanide in the local river system. The release of sediments, cyanide, mercury, and other metals present in the ore such as lead, manganese and arsenic significantly reduces biodiversity downstream the processing plants and enriches metals in bottom sediments and biota. However, methylmercury concentrations in sediments downstream the mining area were recently found to be one order of magnitude lower than upstream or in small tributaries. In this study we investigated cyanide, bacterial activity in water and sediment and mercury methylation potentials in sediments along the Puyango river watershed, measured respectively by in-situ spectrophotometry and incubation with 3H-leucine and 203Hg2+. Free cyanide was undetectable (<1μg·L−1) upstream mining activities, reached 280μg·L−1 a few km downstream the processing plants area and was still detectable about 100km downstream. At stations with detectable free cyanide in unfiltered water, 50% of it was dissolved and 50% associated to suspended particles. Bacterial activity and mercury methylation in sediment showed a similar spatial pattern, inverse to the one found for free cyanide in water, i.e. with significant values in pristine upstream sampling points (respectively 6.4 to 22μgC·mgwet weight−1·h−1 and 1.2 to 19% of total 203Hg·gdry weight−1·day−1) and undetectable downstream the processing plants, returning to upstream values only in the most distant downstream stations. The data suggest that free cyanide oxidation was slower than would be expected from the high water turbulence, resulting in a long-range inhibition of bacterial activity and hence mercury methylation. The important mercury fluxes resultant from mining activities raise concerns about its biomethylation in coastal areas where many mangrove areas have been converted to shrimp farming. [Copyright &y& Elsevier]

Abstract: To study the possibility of modifying diffusional-transport properties of the poly(perfluorosulfonic) acid (Nafion-117) membrane, the silica particles were incorporated in its matrix by in situ sol–gel method. The amount of silica incorporated in the membrane samples was varied by controlling the equilibrating time of the membrane sample in solution containing fixed proportion of precursor tetraethylorthosilicate (TEOS), methanol and water. The silica contents in the membrane samples were characterized by gravimetry, energy dispersive X-ray analysis (EDXRF) and transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) studies showed that there were no significant difference in transition peak temperatures of both samples (Nafion-117 and Nafion/SiO2) in same ionic form except that enthalpies were increased in Nafion/SiO2 samples in all the ionic forms. The increase in enthalpy was due to higher water content in Nafion/SiO2 as compared to Nafion-117 in given ionic form as enthalpies normalized with water content of the respective membrane were comparable. The ion-exchange capacity, water uptake capacity and ion-exchange isotherms of the Na+ +Cs+ and Na+ +Ba2+ binary systems in silica embedded membrane samples were experimentally measured using appropriate radiotracers, and compared with that of pristine Nafion-117 membrane. The specific conductivities of the membrane samples with and without silica were studied in Na+, Cs+ and Ba2+ ionic forms by electrochemical impedance spectroscopy (EIS). The self-diffusion coefficients of Na+, Cs+ and Ba2+ ions in the Nafion/SiO2 were measured by the radiotracer method. It was observed from the experimentally measured specific conductivities and self-diffusion coefficients data that diffusion mobility of Cs+ and Ba2+ counter-ions were enhanced significantly after incorporation of SiO2 in the Nafion-117 matrix. Contrary to this, diffusion mobility of Na+ counter-ion decreased in Nafion/SiO2 sample. The selectivity of Cs+ and Ba2+ counter-ions was reduced in Nafion/SiO2 sample with respect to pristine Nafion-117. [Copyright &y& Elsevier]

To assess the long-term safety of a geological carbon dioxide storage site, the confining properties of the rocks sealing an underground reservoir (caprocks) and their evolution in the presence of CO2 must be characterized. The present study consists in the measurement of the transport parameters of dissolved CO2 through low permeability carbonate-rich caprocks. The properties of interest are the effective permeability and the diffusion coefficients of carbon dioxide dissolution products in water. The impact of carbon dioxide has been evaluated when altering rock samples by diffusion of a CO2-saturated brine under reservoir thermodynamic conditions, and by comparison of the pre- and post-alteration measured values. Permeability was measured by a gas-tracing method and, to study diffusion, radioactive isotopes of carbon (14C) and hydrogen (³H) were used. Despite a porosity increase observed for all the studied samples, the low values of transport parameters, measured initially, were also measured after alteration, showing a non-catastrophic alteration of the material. [ABSTRACT FROM AUTHOR]

Abstract: The enzyme cyclooxygenase-2 (COX-2) is overexpressed in a variety of malignant tumors. This study was designed to develop new radiotracers for imaging of COX-2 in cancer using biomedical imaging technique positron emission tomography (PET). Carbon-11-labeled celecoxib derivatives, [11C]4a–c and [11C]8a–d, were prepared by O-[11C] methylation of their corresponding precursors using [11C]CH3OTf under basic conditions and isolated by a simplified solid-phase extraction (SPE) method in 52 ± 2% (n = 5) and 57 ± 3% (n = 5) radiochemical yields based on [11C]CO2 and decay corrected to end of bombardment (EOB). The overall synthesis time from EOB was 23 min, the radiochemical purity was >99%, and the specific activity at end of synthesis (EOS) was 277.5 ± 92.5 GBq/μmol (n = 5). The IC50 values to block COX-2 for known compounds celecoxib (4d), 4a and 4c were 40, 290 and 8 nM, respectively, and preliminary findings from in vitro biological assay indicated that the synthesized new compounds 4b and 8a–d display similar strong inhibitory effectiveness in the MDA-MB-435 human cancer cell line in comparison with the parent compound 4d. These results encourage further in vivo evaluation of carbon-11-labeled celecoxib derivatives as new potential PET radiotracers for imaging of COX-2 expression in cancer. [Copyright &y& Elsevier]

Abstract: Introduction: The validation and confirmation of clinical usefulness of new and known positron emission tomography (PET) tracers require stable production routes and simple and robust radiochemical procedures. Microfluidic technologies are regarded as an approach that could allow an unprecedented flexibility and productivity in PET radiopharmaceutical research. In this work, we will show how a commercially available microfluidic system can be used for a sequential and repeatable radiosynthesis of three different fluorocholine analogues currently under investigation as tumor tracers. Methods: Advion microfluidic system was used for performing the synthesis and purification of [18F]fluoromethyl, [18F]fluoroethyl or [18F]fluoropropyl choline employing a two-step approach, starting from the corresponding alkyl-ditosylate and reacting the [18F]fluorotosylate obtained in the first step with neat dimethylethanolamine. The purification was obtained using a recyclable SPE cartridge set. Results: The three products, fluoromethylcholine, fluoroethylcholine and fluoropropylcholine, were obtained in good to optimum yields (22%–54% decay corrected) with a 15-min procedure. The production could be restarted several times for producing each one of the tracers without decrease in yields and purities, in accordance with a dose-on-demand (DOD) approach. The final products were formulated in isotonic saline solution. Conclusion: The described approach gives a proof of principle of the enhanced productivity obtainable using a microfluidic approach; in particular, the possibility to produce the reported tracers in a DOD fashion following a homogeneous synthetic and purification approach will foster further studies on the clinical evaluation of the best fluorocholine analogue for prostate cancer imaging without biasing for differences in radiochemical approach. [Copyright &y& Elsevier]

Abstract: Carbon-11-labeled casimiroin analogues were first designed and synthesized as new potential PET agents for imaging of quinone reductase (QR) 2 and aromatase expression in breast cancer. [11C]casimiroin (6-[11C]methoxy-9-methyl-[1,3]dioxolo[4,5-h]quinolin-8(9H)-one, [11C]11) and its carbon-11-labeled analogues 5,6,8-trimethoxy-1-[11C]methyl-4-methylquinolin-2(1H)-one ([11C]17), 8-methoxy-1-[11C]methyl-4-methylquinolin-2(1H)-one ([11C]21a), 6,8-dimethoxy-1-[11C]methyl-4-methylquinolin-2(1H)-one ([11C]21b), and 5,8-dimethoxy-1-[11C]methyl-4-methylquinolin-2(1H)-one ([11C]21c), were prepared from their corresponding precursors with [11C]methyl triflate ([11C]CH3OTf) under basic conditions (NaH) through either O- or N-[11C]methylation and isolated by semi-preparative HPLC method in 40–50% radiochemical yields decay corrected to end of bombardment (EOB), based on [11C]CO2, and 111–185GBq/μmol specific activity at the end of synthesis (EOS). [ABSTRACT FROM AUTHOR]

Abstract: Carbon-11-labeled tricyclic necroptosis inhibitors were first designed and synthesized as new potential PET agents for imaging of tumor necrosis factor α (TNF-α). The target tracers were prepared by O-[11C]methylation of their corresponding precursors using [11C]CH3OTf under basic conditions and isolated by a simplified SPE method in 50–60% radiochemical yields based on [11C]CO2 and decay corrected to end of bombardment (EOB). The overall synthesis time from EOB was 15–20min, the radiochemical purity was >99%, and the specific activity at end of synthesis (EOS) was 111–185GBq/μmol. [ABSTRACT FROM AUTHOR]

Abstract: [18F]Xenon difluoride ([18F]XeF2), was produced by treating xenon difluoride with cyclotron-produced [18F]fluoride ion to provide a potentially useful agent for labeling novel radiotracers with fluorine-18 (t 1/2 =109.7min) for imaging applications with positron emission tomography. Firstly, the effects of various reaction parameters, for example, vessel material, solvent, cation and base on this process were studied at room temperature. Glass vials facilitated the reaction more readily than polypropylene vials. The reaction was less efficient in acetonitrile than in dichloromethane. Cs+ or K+ with or without the cryptand, K 2.2.2, was acceptable as counter cation. The production of [18F]XeF2 was retarded by K2CO3, suggesting that generation of hydrogen fluoride in the reaction milieu promoted the incorporation of fluorine-18 into xenon difluoride. Secondly, the effect of temperature was studied using a microfluidic platform in which [18F]XeF2 was produced in acetonitrile at elevated temperature (≥85°C) over 94s. These results enabled us to develop a method for obtaining [18F]XeF2 on a production scale (up to 25mCi) through reaction of [18F]fluoride ion with xenon difluoride in acetonitrile at 90°C for 10min. [18F]XeF2 was separated from the reaction mixture by distillation at 110°C. Furthermore, [18F]XeF2 was shown to be reactive towards substrates, such as 1-((trimethylsilyl)oxy)cyclohexene and fluorene. [ABSTRACT FROM AUTHOR]

Abstract: The Chilean blue mussel (Mytilus chilensis, Hupe 1854) represents the most important bivalve exploited along the Chilean coast and is a major food source for the Chilean population. Unfortunately, local fish and shellfish farming face severe problems as a result of bioaccumulation of toxic trace metals into shellfishes. Blue mussels collected along the Chilean coasts contain levels of Cd above the regulatory limits for human consumption. In this study, we examined the bioaccumulation, depuration and organ distribution of Cd in the M. chilensis, from 109Cd-labelled bulk seawater and from feeding with 109Cd-labelled algae. The uptake of 109Cd via seawater displayed a simple exponential kinetic model suggesting that cadmium activity tends to reach an equilibrium value of 1.838±0.175ngg−1 (mean±asymptotic standard error, p <0.001) after 78±9 days. The depuration rate for 109Cd accumulated via seawater was slow, with only 21% of the total 109Cd accumulated in the whole mussel being eliminated after 52 days. Total elimination of Cd in mussels was adequately described by a double component kinetic model, in which the biological half-life for the long-lived component represents more than 6 months. In contrast, depuration after radiolabelled food uptake was fast, reaching only 20% of retention in 10 days. This knowledge of the long half-life of cadmium accumulated via seawater as well as the non-negligible level of cadmium accumulated into the shells is relevant to the management of Cd levels in this species and the refinement of detoxification processes in order to comply with authorized Cd levels. [ABSTRACT FROM AUTHOR]

Abstract: Carbon-11-labeled tariquidar derivatives were first designed and synthesized as new PET agents for imaging of breast cancer resistance protein. The target tracers were prepared by O-[11C]methylation of their corresponding acid precursors using [11C]CH3OTf under basic conditions and isolated by a simplified solid-phase extraction (SPE) method in 50–60% radiochemical yields based on [11C]CO2 and decay corrected to end of bombardment (EOB). The overall synthesis time from EOB was 15–20min, the radiochemical purity was >99%, and the specific activity at end of synthesis (EOS) was 111–185GBq/μmol. [Copyright &y& Elsevier]

Abstract: The environment is impacted by natural and anthropogenic disturbances that occur at different spatial and temporal scales, and that lead to major changes and even disequilibria when exceeding the resiliency capacities of the ecosystem. With an annual mean flow of 1700m3 s−1, the Rhône River is the largest of the western Mediterranean basin. Its annual solid discharges vary between 2 and 20Mt, with flood events responsible for more than 70% of these amounts. In the marine coastal area, close to the mouth, both flocculation and aggregation lead to the formation of fine-grained deposits, i.e. the prodelta. This area is characterized by sediment accumulation rates up to 20–50cmyr−1 and high accumulations of particle reactive contaminants such as various man-made radionuclides released into the river by nuclear facilities or arising form prior atmospheric nuclear tests (1954–1980) and the Chernobyl accident (April 1986). This prodelta, however, cannot be considered as a permanent repository for particle reactive pollutants since it is subjected to reworking processes. Sediment dynamics had to be linked to the influences of hydrodynamic and atmospheric events such as high flow rates or storms close to the Rhône River mouth. An experiment was carried out during the winter 2006 based on the deployment of two ADCPs and six altimeters at the Grand Rhône mouth for several months. This type of installation has never been used before in this area because of the hard meteorological conditions and the strong fishing activities. However, results showed pluricentimetric rises of the sedimentary level just after river flood events and decreases during storms, generated by southeast winds. Radiotracers and grain size depth profiles helped to characterise the studied events and to establish inventories of sediments and radionuclides. A cruise (CARMEX) was carried out during this same period to collect water samples, suspended particles and sediment cores. The results enabled us to link both river flow and wind characteristics to events recorded on the sea floor, i.e. resuspension, accumulation, consolidation, etc. Deposits of 11cm of sediments were estimated during flood periods and bottom shear stresses up to 5Nm−2 were calculated during sediment erosion phases. [Copyright &y& Elsevier]

Abstract: The present work aimed at better understanding metal and metalloid bioaccumulation in the edible Pacific blue shrimp Litopenaeus stylirostris, using both laboratory and field approaches. In the laboratory, the bioaccumulation kinetics of Ag, Cd, Co, Cr, and Zn have been investigated in shrimp exposed via seawater and food, using the corresponding γ-emitting radiotracers (110mAg, 109Cd, 57Co, 51Cr, and 65Zn) and highly sensitive nuclear detection techniques. Results showed that hepatopancreas and intestine concentrated the metals to the highest extent among the blue shrimp organs and tissues. Moulting was found to play a non negligible detoxification role for Co, Cr and, to a lesser extent, Zn. Metal retention by L. stylirostris widely varied (from a few days to several months), according to the element and exposure pathway considered (a given metal was usually less strongly retained when ingested with food than when it was taken up from the dissolved phase). In the field study, Ag, As, Cd, Co, Cr, Cu, Mn, Ni, and Zn were analysed in shrimp collected from a New Caledonian aquaculture pond. Metal concentrations in the shrimp muscles were generally relatively low and results confirmed the role played by the digestive organs and tissues in the bioaccumulation/storage/detoxification of metals in the Pacific blue shrimp. Preliminary risk considerations indicate that consumption of the shrimp farmed in New Caledonia is not of particular concern for human health. [ABSTRACT FROM AUTHOR]

Abstract: Carbon-11-labeled piperidine ring of N-[ω-(6-methoxynaphthalen-1-yl)alkyl] derivatives were first designed and synthesized as new selective PET σ 1 receptor probes. The target tracers were prepared by O-[11C]methylation of their corresponding phenolic hydroxyl precursors using [11C]CH3OTf under basic conditions and isolated by a simplified SPE method in 40–50% radiochemical yields based on [11C]CO2 and decay corrected to EOB. The overall synthesis time from EOB was 15–20min, the radiochemical purity was >99%, and the specific activity at EOS was 111–185GBq/μmol. [Copyright &y& Elsevier]

Abstract: Carbon-11-labeled 4-aryl-4H-chromenes, 2-amino-7-(dimethylamino)-4-(3-[11C]methoxy-5-methoxyphenyl)-4H-chromene-3-carbonitrile ([11C]6a), 2-amino-4-(3-bromo-4-[11C]methoxy-5-methoxyphenyl)-7-(dimethylamino)-4H-chromene-3-carbonitrile ([11C]6c), 2-amino-4-(3-[11C]methoxy-5-methoxyphenyl)-4,7-dihydropyrano[2,3-e]indole-3-carbonitrile ([11C]6d), 2-amino-4-(3-bromo-4-[11C]methoxy-5-methoxyphenyl)-4,7-dihydropyrano[2,3-e]indole-3-carbonitrile ([11C]6f), 2-amino-4-(3-[11C]methoxy-5-methoxyphenyl)-4,9-dihydropyrano[3,2-g]indole-3-carbonitrile ([11C]6g), 2-amino-4-(3-bromo-4-[11C]methoxy-5-methoxyphenyl)-4,9-dihydropyrano[3,2-g]indole-3-carbonitrile ([11C]6i), 2-amino-4-(3-[11C]methoxy-5-methoxyphenyl)-7-methyl-4,7-dihydropyrano[2,3-e]indole-3-carbonitrile ([11C]6j) and 2-amino-4-(3-bromo-4-[11C]methoxy-5-methoxyphenyl)-7-methyl-4,7-dihydropyrano[2,3-e]indole-3-carbonitrile ([11C]6l), were prepared by O-[11C]methylation of their corresponding precursors using [11C]CH3OTf under basic conditions and isolated by a simplified solid-phase extraction (SPE) method in 30–50% radiochemical yields based on [11C]CO2 and decay corrected to end of bombardment (EOB). The overall synthesis time from EOB was 15–20min, the radiochemical purity was >99%, and the specific activity at end of synthesis (EOS) was 111–185GBq/μmol. [Copyright &y& Elsevier]

Abstract: Aromatase and steroid sulfatase (STS) are particularly attractive targets in the treatment of estrogen-receptor-positive breast cancer and the development of enzyme-based cancer imaging agents for the biomedical imaging technique positron emission tomography (PET). New carbon-11-labeled sulfamate derivatives were first designed and synthesized as potential PET dual aromatase–steroid sulfatase inhibitor (DASSI) radiotracers for imaging of aromatase and STS expression in breast cancer. The target tracers 5-(((4-cyanophenyl)(4H-1,2,4-triazol-4-yl)amino)methyl)-2-[11C]methoxyphenyl sulfamate ([11C]8a) and 4-(((4-cyanophenyl)(4H-1,2,4-triazol-4-yl)amino)methyl)-2-[11C]methoxyphenyl sulfamate ([11C]8b) were prepared from their corresponding precursors 5-(((4-cyanophenyl)(4H-1,2,4-triazol-4-yl)amino)methyl)-2-hydroxyphenyl sulfamate (16) and 4-(((4-cyanophenyl)(4H-1,2,4-triazol-4-yl)amino)methyl)-2-hydroxyphenyl sulfamate (21) with [11C]CH3OTf under basic conditions through the O-[11C]methylation and isolated by the reversed-phase high pressure liquid chromatography (HPLC) method in 30–45% radiochemical yields based on [11C]CO2 and decay corrected to end of bombardment (EOB). The specific activity at end of synthesis (EOS) was 111–185GBq/μmol. [Copyright &y& Elsevier]