Search Results (69)

Accurate methane emission estimates are essential for climate policy, yet current field methods often struggle with spatial constraints and source complexity. Ground-based mobile approaches frequently miss key plume features, introducing bias and uncertainty in emission rate estimates. This study addresses these limitations by using small unmanned aerial systems equipped with precision gas sensors to measure methane alongside co-released tracers. We tested whether arc-shaped flight paths and alternative ratio estimation methods could improve the accuracy of tracer-based emission quantification under real-world constraints. Controlled releases using ethane and nitrous oxide tracers showed that (1) arc flights provided stronger plume capture and higher correlation between methane and tracer concentrations than traditional flight paths; (2) the cumulative sum method yielded the lowest relative error (as low as 3.3%) under ideal mixing conditions; and (3) the arc flight pattern yielded the lowest relative error and uncertainty across all experimental configurations, demonstrating its robustness for quantifying methane emissions from downwind plume measurements. These findings demonstrate a practical and scalable approach to reducing uncertainty in methane quantification. The method is well-suited for challenging environments and lays the groundwork for future applications at the facility scale. Full article

This study assesses the clinical deployment of SubtlePET™, a commercial AI-based denoising algorithm, across three radiotracers—¹⁸F-FDG, ⁶⁸Ga-PSMA-11, and ¹⁸F-FDOPA—with the goal of improving image quality while reducing injected activity, technologist radiation exposure, and scan time. A retrospective analysis on a digital PET/CT system showed that SubtlePET™ enabled dose reductions exceeding 33% and time savings of over 25%. AI-enhanced images were rated interpretable in 100% of cases versus 65% for standard low-dose reconstructions. Notably, 85% of AI-enhanced scans received the maximum Likert quality score (5/5), indicating excellent diagnostic confidence and noise suppression, compared to only 50% with conventional reconstruction. The quantitative image quality improved significantly across all tracers, with SNR and CNR gains of 50–70%. Radiotracer dose reductions were particularly substantial in low-BMI patients (up to 41% for FDG), and the technologist exposure decreased for high-exposure roles. The daily patient throughput increased by an average of 4.84 cases. These findings support the robust integration of SubtlePET™ into routine clinical PET practice, offering improved efficiency, safety, and image quality without compromising lesion detectability. Full article

Mine ventilation systems are critical for ensuring operational safety, yet air leakage remains a pervasive challenge, leading to energy inefficiency and heightened safety risks. Traditional tracer gas methods, while effective in simple networks, exhibit significant errors in complex multi-entry systems due to static empirical parameters and environmental interference. This study proposes an integrated methodology that combines multi-path airflow analysis with dynamic longitudinal dispersion coefficient correction to enhance the accuracy of air leakage detection. Utilizing sulfur hexafluoride (SF6) as the tracer gas, a phased release protocol with temporal isolation was implemented across five strategic points in a coal mine ventilation network. High-precision detectors (Bruel & Kiaer 1302) and the MIVENA system enabled synchronized data acquisition and 3D network modeling. Theoretical models were dynamically calibrated using field-measured airflow velocities and dispersion coefficients. The results revealed three deviation patterns between simulated and measured tracer peaks: Class A deviation showed 98.5% alignment in single-path scenarios, Class B deviation highlighted localized velocity anomalies from Venturi effects, and Class C deviation identified recirculation vortices due to abrupt cross-sectional changes. Simulation accuracy improved from 70% to over 95% after introducing wind speed and dispersion adjustment coefficients, resolving concealed leakage pathways between critical nodes and key nodes. The study demonstrates that the dynamic correction of dispersion coefficients and multi-path decomposition effectively mitigates errors caused by turbulence and geometric irregularities. This approach provides a robust framework for optimizing ventilation systems, reducing invalid airflow losses, and advancing intelligent ventilation management through real-time monitoring integration. Full article

The indoor climate quality in classrooms at the University of Coimbra, Portugal, was investigated as part of the 3SqAir project, supported by the Interreg SUDOE program. This research focused on two equipped classrooms with different ventilation systems: natural and mechanical ventilation. Both classrooms were continuously monitored for IEQ parameters: thermal comfort, indoor air quality, noise, and lighting during heating and cooling seasons. Air temperature, relative humidity, CO₂ concentration, particulate matter, nitrogen dioxide, volatile organic compounds, formaldehyde, sound pressure level, and illuminance were measured. Outdoor weather conditions were also recorded. The primary focus was on air temperature, CO₂ concentrations, and relative humidity, while air change rates (ACH) were estimated using the Tracer Gas Method. The results showed inadequate thermal conditions in both classrooms, particularly during the heating season. Most weekly mean CO₂ concentrations were within acceptable limits, while ACH were below standard recommendations in four CO₂ decay phases. Simulations of CO₂ decay revealed further air quality gaps in each room. Corrective measures within the 3SqAir project framework were suggested for approval and implementation while monitoring continues. This work represents the first phase in an evolving study towards developing sustainable strategies for improving indoor air quality in classrooms. Full article

Background/Objectives: Molecular imaging, especially PET, has advanced significantly, shifting from metabolic radiotracers like 2-deoxy-2-[¹⁸F]fluoro-D-glucose [¹⁸F]FDG to target-specific probes. Among these, αvβ6-integrin has emerged as a promising target in cancer and non-cancer diseases. This review focuses on the radiochemical properties and initial clinical applications of the [⁶⁸Ga]Ga-Trivehexin PET probe. Methods: The literature review on [⁶⁸Ga]Ga-Trivehexin systematically evaluated both preclinical and clinical studies, with particular emphasis on its radiochemical characteristics and preliminary clinical applications, while highlighting advancements, associated challenges, and the potential for future developments in the field. Results: This study highlights the significant advancements achieved with [⁶⁸Ga]Ga-Trivehexin in the field of molecular imaging. The optimized multimeric system has substantially enhanced the radiotracer’s pharmacokinetic properties, binding affinity, and selectivity for αvβ6 integrin, demonstrating up to an 18-fold improvement compared to previous monomeric tracers. The synthesis protocol has been refined to achieve high radiochemical purity (>95%), essential for safe clinical use. Preliminary clinical applications, particularly in head and neck cancer (HNC) and pancreatic ductal adenocarcinoma (PDAC), have shown promising results, with high detection rates and improved differential diagnosis compared to [¹⁸F]FDG. Furthermore, [⁶⁸Ga]Ga-Trivehexin PET/CT has shown potential in non-oncological conditions, such as idiopathic pulmonary fibrosis (IPF) and primary hyperthyroidism, suggesting broader clinical applicability. Conclusions: [⁶⁸Ga]Ga-Trivehexin is a promising PET probe for imaging αvβ6-integrin in cancers and non-oncological diseases like idiopathic pulmonary fibrosis (IPF) and primary hyperparathyroidism (PHP). Full article

Subsurface contamination can migrate upward into overlying buildings, exposing the buildings’ inhabitants to contaminants that can cause detrimental health effects. This phenomenon is known as vapor intrusion (VI). When evaluating a building for VI, one must understand that seasonal and short-term variability are significant factors in determining the reasonable maximum exposure (RME) to the occupants. RME is a semi-quantitative term that refers to the lower portion of the high end of the exposure distribution—conceptually, above the 90th percentile exposure but less than the 98th percentile exposure. Samples were collected between December 2020 and April 2022 at six non-residential commercial buildings in Fairbanks, Alaska. The types of samples collected included indoor air (IA); outdoor air; subslab soil gas; soil gas; indoor radon; differential pressure; indoor and outdoor temperature; heating, ventilation, and air conditioning (HVAC) parameters; and other environmental factors. The buildings in close proximity to the volatile organic compound (VOC) source/release points presented less variability in indoor air concentrations of trichloroethylene (TCE) and tetrachloroethylene (PCE) compared to the buildings farther down gradient in the contaminated groundwater plume. The VOC data pattern for the source area buildings shows an outdoor air temperature-dominated behavior for indoor air concentrations in the summer season. HVAC system operations had less influence on long-term indoor air concentration trends than environmental factors, which is supported by similar indoor air concentration patterns independent of location within the plume. The use of soil temperature and indoor/outdoor temperatures as indicators and tracers (I&Ts) across the plume as predictors of the sampling period could produce a good estimation of the RME for the building occupants. These results, which show the use of soil temperature and indoor/outdoor temperatures as I&Ts, will help advance investigative methods for evaluation of VI in similar settings and thereby improve the protection of human health in indoor environments. Full article

Background/Objectives: Over the past four years, ⁶⁸Ga-fibroblast activation protein inhibitor (FAPI) positron emission tomography/computed tomography (PET/CT) has been established at a tertiary cancer care facility in Jordan. This retrospective study aims to explore tracer uptake metrics across various epithelial neoplasms, identify diagnostic pitfalls associated with ⁶⁸Ga-FAPI PET/CT, and evaluate the influence of ⁶⁸Ga-FAPI PET/CT staging results on changes in therapeutic intent compared to gold standard molecular imaging modalities. Methods: A total of 48 patients with biopsy-confirmed solid tumors underwent 77 ⁶⁸Ga-FAPI PET/CT examinations for molecular imaging assessment, encompassing neoplasms originating from the gastrointestinal tract, head and neck, hepatobiliary system, pancreas, breast, and lung. Results: Notably, pancreaticobiliary tumors exhibited the highest tracer uptake, with mean maximum standardized uptake values (SUVmax) and tumor-to-background ratios (TBR) surpassing 10. A comparative sub-analysis of ⁶⁸Ga-FAPI PET metrics in 20 treatment-naïve patients revealed a significant correlation between ⁶⁸Ga-FAPI uptake metrics and tumor grade (Spearman’s rho 0.83; p = 0.00001). Importantly, the results from ⁶⁸Ga-FAPI PET/CT influenced treatment decisions in 35.5% of the cases, primarily resulting in an escalation of management plans. A total of 220 diagnostic challenges were identified across 88.3% of the scans, predominantly within the musculoskeletal system, attributed to degenerative changes (99 observations). Conclusions: This comprehensive analysis highlights the potential significance of ⁶⁸Ga-FAPI PET/CT in oncological imaging and treatment strategy, while also emphasizing the necessity for meticulous interpretation to mitigate diagnostic challenges. Full article

Liquid vermicompost (LVC) is one of the organic ingredients for improving plant growth. This study aims to investigate the impact of the application of LVC coating formulations in distinct ratios on seeding emergence, seedling growth parameters, and nitrogen content as well as the systemic uptake characteristics in seedlings. Coating formulations contained gum arabic (GA) mixed with 5–15% of LVC and were applied to pumpkin seeds and compared to non-coated seeds. All samples were stored under cold and ambient conditions for 3 months to evaluate the performance of the coating. Results showed no statistical distinctions in the percentage of seedling emergence. Nevertheless, the 5LVC-GA in the organic formulation significantly increased shoot length, seedling growth rate (SGR), seedling vigor index (SVI), and nitrogen content (%) in the coated seedlings. Additionally, the evaluation of seedling uptake was achieved using rhodamine B as a fluorescent tracer which was diluted in the organic formulation. This explored the transportation of the treatment within a seedling. Therefore, the application of an optimum concentration of 5LVC-GA treatment can improve seedling growth and nitrogen accumulation. This could be confirmed with fluorescence imaging of translocation to seedling organs. However, seed storability declines over three months, emphasizing the need for better coatings and packaging solutions. Full article

This study analyzes the shortcomings of South Korea’s current evaluation method of ventilation performance for apartment buildings and suggests improvements. The current Korean regulations rely on the air change rate method, which is a prescriptive method and thus inadequately measures indoor air quality practically. Therefore, this study reviews various standards, finding that these standards can be categorized into those evaluating the mechanical performance of ventilators and those assessing indoor ventilation performance. This study highlights that the standards evaluating indoor ventilation performance are based on the tracer gas method but lack clear testing procedures and boundary conditions. This research also reviews the various previous research articles, noting that Korean research places emphasis on system design parameters, while international research focuses on architectural factors. It also identifies inconsistencies in the experimental setups across studies. To improve the current evaluation methods, the research suggests enhancing the tracer gas method with clear testing procedures and introducing indicators such as the age of air and uniformity coefficient together. Since the air change rate method does not consider the actual airflows and distribution in indoor spaces, this method is limited to deriving improvements in indoor ventilation performance. However, the suggested tracer gas method and indicators can be used to discover the optimal locations of vents for better indoor air quality or to drive a better building design to achieve better indoor ventilation performance. In other words, these enhancements aim to provide more accurate and comprehensive insights into the effectiveness of indoor ventilation systems, helping engineers, designers, and residents better understand and improve indoor air quality. Full article

Over the past decade, prostate-specific membrane antigen positron emission tomography (PSMA-PET) has revolutionized prostate cancer (PCa) imaging, offering greater sensitivity and specificity compared to conventional imaging modalities such as CT, MRI, and bone scintigraphy. PSMA-PET is particularly valuable in staging newly diagnosed patients with intermediate- and high-risk disease, detecting biochemical recurrence, and evaluating metastatic cases. By utilizing radiotracers that accumulate specifically in PSMA-expressing cells, even small metastases can be detected, offering a detailed assessment of cancer extent and enabling more targeted diagnostic evaluations. Among the most utilized radiotracers, [⁶⁸Ga]- and [¹⁸F]-labeled PSMA tracers enable precise imaging even with low disease burden. This diagnostic precision also supports advanced therapeutic approaches, including metastasis-directed therapy for oligometastatic cases and systemic treatment options, such as radioligand therapy, which presents new treatment perspectives for metastatic, castration-resistant PCa. This review examines the evolution of PSMA-PET in the diagnostics and therapy of PCa while comparing the current recommendations from leading clinical guidelines. The integration of PSMA-PET into clinical practice has redefined the management of PCa, improving diagnostic accuracy and enabling personalized treatment strategies, while lacking prospective long-term outcome data. As PSMA-PET continues to expand in clinical application, this review highlights its significant advancements while critically addressing limitations to ensure balanced and evidence-based implementation in prostate cancer care. Full article

Background/Objectives: PET imaging of bacterial infection could potentially provide added benefits for patient care through non-invasive means. [⁶⁸Ga]Ga-desferrioxamine B—a radiolabelled siderophore—shows specific uptake by human-pathogenic bacteria like Staphylococcus aureus or Pseudomonas aeruginosa and sufficient serum stability for clinical application. In this report, we present data for automated production of [⁶⁸Ga]Ga-desferrioxamine B on two different cassette-based synthesis modules (Modular-Lab PharmTracer and GRP 3V) utilising commercially obtainable cassettes together with a licensed ⁶⁸Ge/⁶⁸Ga radionuclide generator. Methods: Quality control, including the determination of radiochemical purity, as well as a system suitability test, was set up via RP-HPLC on a C18 column. The two described production processes use an acetic acid/acetate buffer system with ascorbic acid as a radical scavenger for radiolabelling, yielding ready-to-use formulations with sufficient activity yield. Results: Batch data analysis demonstrated radiochemical purity of >95% by RP-HPLC combined with ITLC and excellent stability up to 2 h after synthesis. Specifications for routine production were set up and validated with four masterbatches for each synthesis module. Conclusions: Based on this study, an academic clinical trial for imaging of bacterial infection was initiated. Both described synthesis methods enable automated production of [⁶⁸Ga]Ga-desferrioxamine B in-house with high reproducibility for clinical application. Full article

CO₂ geological storage, as a large-scale, low-cost, carbon reduction technology, has garnered widespread attention due to its safety. Monitoring potential leaks is critical to ensuring the safety of the carbon storage system. Geochemical monitoring employs methods such as gas monitoring, groundwater monitoring, tracer monitoring, and isotope monitoring to analyze the reservoir’s storage state and secondary changes after a CO₂ injection. This paper summarizes the recent applications and limitations of geochemical monitoring technologies in CO₂ geological storage. In gas monitoring, the combined monitoring of multiple surface gasses can analyze potential gas sources in the storage area. In water monitoring, pH and conductivity measurements are the most direct, while ion composition monitoring methods are emerging. In tracer monitoring, although artificial tracers are effective, the environmental compatibility of natural tracers provides them with greater development potential. In isotope monitoring, C and O isotopes can effectively reveal gas sources. Future CO₂ geological storage project monitoring should integrate various monitoring methods to comprehensively assess the risk and sources of CO₂ leakage. The incorporation of artificial intelligence, machine learning technologies, and IoT monitoring will significantly enhance the accuracy and intelligence of numerical simulations and baseline monitoring, ensuring the long-term safety and sustainability of CO₂ geological storage projects. Full article

This study aimed to evaluate the sulfur hexafluoride (SF₆) tracer technique for estimating methane (CH₄) emissions in dual-flow continuous culture systems (DFCCS). In experiment 1 (Exp1), fermenters were filled with water, and known CH₄ concentrations (0, 1.35, 2.93, or 4.43 g/d) were injected using permeation tubes with SF₆ release rates (3.30 or 9.65 mg/d). Headspace gas was collected using canisters, and the SF₆ technique estimated CH₄ recovery. Experiment 2 (Exp2) involved a DFCCS fermentation trial with ruminal fluid from three Holstein cows, testing diets with soybean meal or its partial replacement (50%) by Chlorella or Spirulina. Headspace gas was collected at intervals post-feeding. Standard curves for SF₆ and CH₄ quantification were inadequate for DFCCS samples, with the CH₄:SF₆ ratio differing from standards, indicating the data needs further SF₆ release rate evaluation. In Exp1, a high correlation (r = 0.97) was found between infused and calculated CH₄, indicating good repeatability. Low and high SF₆ rates performed similarly at low CH₄ infusion, but high SF₆ overestimated CH₄ at high infusion. Exp2 showed CH₄ emissions irrespective of SF₆ rate and indicated reduced CH₄ emissions and increased NDF degradation with algae-containing diets. Further evaluation of the SF₆ tracer technique is warranted for DFCCS. Full article

There is a fundamental issue in the launching system with the modular charge technology, which is an unsteady gas–solid flow in the sequence-change space within a short period of time. It leads to complex particle behavior, causing the strong pulsation of particle energy released during the combustion process. As a result, a large initial pressure wave is generated, which damages the launching stability. In this work, a 3D gas–solid flow model is developed based on the computational fluid dynamics–discrete element method (CFD-DEM) model to analyze the particle behavior in the launching system with different numbers of modules. The rationality of the model is verified through the experiment. It is found that the particles near the cover of the rightmost module move out of the module rapidly and collide with the right face of the chamber, forming a retained particle layer. When particles are stationary, the distribution of particles consists of slope accumulations and horizontal accumulation. With the increase in the module number, the position changes of all tracer particles are decreased, both the thickness and the length of the horizontal shape are increased, the variation laws of the slope stack height change from exponential to linear, and the distribution of particles becomes uniform. Full article

This study aimed to develop and implement a nanotechnology-based alternative to traditional tracers used in the oil and gas industry for assessing interwell connectivity. A simple and rapid hydrothermal protocol for synthesizing carbon quantum dots (CQDs) using agroindustry waste was implemented. Three commercial CQDs were employed (CQDblue, CQDgreen, and CQDred); the fourth was synthesized from orange peel (CQDop). The CQDs from waste and other commercials with spherical morphology, nanometric sizes less than 11 nm in diameter, and surface roughness less than 3.1 nm were used. These tracers demonstrated high colloidal stability with a negative zeta potential, containing carbonyl-type chemical groups and unsaturations in aromatic structures that influenced their optical behavior. All materials presented high colloidal stability with negative values of charge z potential between −17.8 and −49.1. Additionally, individual quantification of these tracers is feasible even in scenarios where multiple CQDs are present in the effluent with a maximum percentage of interference of 15.5% for CQDop in the presence of the other three nanotracers. The CQDs were injected into the field once the technology was insured under laboratory conditions. Monitoring the effluents allowed the determination of connectivity for five first-line producer wells. This study enables the application of CQDs in the industry, particularly in fields where the arrangement of injector and producer wells is intricate, requiring the use of multiple tracers for a comprehensive description of the system. Full article