Quantitative Analysis Research Articles

Decoding how the older adults identify misinformation: an analysis of internal mechanisms

Introduction. This study aims to explore the key factors influencing misinformation recognition among older adults, understand the internal mechanisms of how they identify misinformation, and ultimately promote age-friendly improvements in the information environment of the AI era. Method. Using in-depth interviews, we selected 55 misinformation recognition events as research subjects and applied content analysis and binary logistic regression methods. Analysis. Quantitative content analysis was conducted on interview data, followed by binary logistic regression analysis on nine variables, which were later consolidated into three dimensions. Results. The findings reveal that public information sources, interpersonal information sources, information content, information perspectives, and evidence significantly impact misinformation recognition. Information sources play a crucial role in older adults' misinformation recognition, while the influence of information dimensions is not fully realized, and the direct impact of the information users’ dimension is limited. Conclusion. These findings reveal the mechanisms of misinformation identification by older adults, emphasizing the need for age-friendly improvements in information literacy and digital environments to enhance older adults' ability to recognize misinformation.

Analysis of Unloading Time for Fish Catches at the Kasiwa Mamuju Fish Landing Base, West Sulawesi

Kasiwa Fish Landing Base (PPI) in Mamuju, West Sulawesi, is a center of fisheries activity that plays an important role in supporting the capture fisheries sector. This research aims to analyze the efficiency of unloading fish catches and the factors that influence it. The method used in this research was purposive sampling, with respondents consisting of active fishermen and port management staff. The aim of this research is to evaluate the duration of the catch unloading process at the Kasiwa Fish Landing Base (PPI) located in Mamuju, West Sulawesi. As the fishing industry advances, the importance of efficiency in unloading procedures becomes increasingly significant to boost productivity and reduce losses. This research uses an observational method with measurements of demolition time carried out over a certain period of time, as well as quantitative data analysis to identify factors that influence the duration of demolition. This includes the type of fish, volume of catch, and weather conditions at the time of unloading. The results show that the time required for disassembly ranges from 30 to 120 minutes, depending on the variables involved. It is hoped that these findings can provide suggestions for fisheries industry players to improve operational efficiency at PPI Kasiwa and become a reference for further research in the field of fisheries and marine product processing.

“You can’t imagine how hard it is”: hardship streamers in live crowdfunding

Introduction. The combination of Live streaming and E-commerce also offers opportunities for people whose family members are severely ill, disabled, or old and facilitates their ability to raise funds by selling commodities and receiving virtual gifts. Unlike other streamers, hardship live streamers are driven by unique motivations and may employ distinct self-presentation techniques. Method. We analysed TikTok video clips and sales data from 14 male and female hardship streamers. Analysis. We used both quantitative and qualitative analyses of the data, including topic modelling, sentiment analysis, and thematic content analysis. Results. We found that 1) hardship streamers used multi-modal cues to facilitate interactivity and authenticity, as they emphasized their hardship and promoted the product; 2) higher literacy level of the streamers and the use of a positive tone positively correlated with better sales; 3) hardship storytelling positively correlated with the time the audience stayed in their live streaming sessions; and 4) females focused more on their hardships, used a more negative tone, and talked faster than males. Conclusion. We provide a unique understanding of the effectiveness of self-presentation strategies used by marginalized live streamers in raising funds on TikTok.

The impact of ideological and political education on the psychological and behavioral biomechanisms in medical students’ life concept formation: A multidisciplinary exploration

In the cultivation of medical ethics, sense of responsibility and humanistic care, the role of Ideological and political education is increasingly significant. This paper studies and analyzes the practical path of Ideological and political education in the concept of life education, and explores its shaping effect on medical students’ values of life, professional ethics and humanistic quality. Through a questionnaire survey of 300 medical students, combined with quantitative data analysis, the study found that ideological and political education can significantly improve students’ cognition level of outlook on life (p < 0.05), and has a positive effect in strengthening medical ethics and professional ethics. In addition, in terms of practice path, combined with case analysis and classroom teaching mode innovation, the study proposed a systematic implementation scheme of Ideological and political education, and verified that the scheme has high operability and effectiveness in cultivating the effect of students’ Outlook on life (the effect increased by about 22%). The results show that the value of Ideological and political education in the life outlook education of medical majors has become an important support point for the cultivation of medical talents, and has far-reaching significance for improving the comprehensive quality and humanistic care consciousness of medical students.

Image-assisted textural analysis of plagioclase crystals in volcanic rocks: an application to lavas erupted on 2021 at Pacaya volcano, Guatemala

The adoption of semi-automated image processing methods to investigate geo-petrological processes has grown quickly in recent years. Utilizing multivariate statistical analysis of X-ray maps, these methods effectively extract quantitative textural, chemical, and modal parameters from selected thin sections or micro-domains in volcanic samples whose constituents can show peculiar textures due to the magmatic processes involved. In this study, we have processed X-ray maps of major elements from the 2021 basaltic lava rocks of Pacaya volcano (Guatemala) through the Quantitative X-ray Map Analyzer (Q-XRMA) software. The processing strategy is based on the sequential application of the Principal Components Analysis and the supervised Maximum Likelihood Classification algorithms that allow us distinguishing among rock constituents (mineral phases, vesicles and glasses), quantifying their modal abundances, and identifying textural and chemical variations in a simplified and quick process. Here, the capability of the software has been applied to plagioclase crystals, whose textural and chemical complexities are faithful recorders of the physical and chemical conditions and processes controlling the evolution of the magmatic system. Plagioclase displays a variable extent of disequilibrium at the core and rim, as well as growth textures developed at different degrees of undercooling. This variability makes it very difficult to establish how many crystal populations are present in a sample, and to objectively decide whether there are crystals that can be considered representative of a population. The procedure applied in this study has proved to be effective for rapidly gathering chemical and textural data on plagioclase, and quantitatively document the distribution of crystals according to their size, shape, and compositions. Results demonstrate that the chemical and textural variability of crystals can be fully discerned at microscopic scale, and thus it can be adopted as a template for interpretation of magmatic processes.

Quantitative analysis of the mechanism of biochar in alleviating product inhibition in different fermentative hydrogen production processes

Dark fermentation is a biological process that converts organic molecules into molecular hydrogen and stands out as one of the most promising methods for extracting bioenergy from wastewater. The accumulation of end-products causes varying inhibitory effects on the process, posing a key challenge. This study explored the efficacy and mechanisms of biochar as a cost-effective solution to mitigating the inhibitory effects of end-products in major types of dark fermentative hydrogen production processes and provided for the first time a quantitative analysis of the relative contribution of each mechanistic pathway. Results showed that biochar was more effective in butyrate-type than ethanol-type fermentations. In butyrate-type fermentation facing endogenous and exogenous volatile acid inhibition, biochar increased hydrogen production by 145.74% and 64.95%, respectively. In ethanol-type fermentation, biochar increased hydrogen production by 10.53% and 18.09% under endogenous and exogenous inhibitions from ethanol, respectively. Mechanistic analyses revealed three primary pathways through which biochar mitigated product inhibition: pH buffering, cell colonization, and inhibitor adsorption. The relative contribution of each pathway varied by fermentation type. In butyrate-type fermentation, pH buffering was critical, accounting for 42.9% of the mitigation effect, while cell colonization was primary in ethanol-type fermentation, contributing 32.4%. This study demonstrated the different roles of biochar in mitigating production inhibition in diverse fermentation types, highlighting its potential to enhance hydrogen energy recovery in dark fermentation.Graphic

Knowledge and practices of regional and rural general practitioners in the identification and management of intimate partner and family violence: a mixed methods study in Western Australia

BackgroundGeneral Practitioners (GPs) are well placed to identify and assist patients experiencing intimate partner violence (IPV) and family violence (FV). However, patients experiencing IPV/FV can be under-detected or inadequately assisted when GPs do not have the necessary confidence, knowledge, attitudes or skills for this. Given the high rates of IPV/FV in the Australian regional setting where this study was conducted, this investigation explored the confidence, knowledge, attitudes and practices of local GPs in identifying and managing patients who are experiencing IPV/FV.MethodsThis mixed methods study utilised a survey tool adapted from a review of existing instruments. The adapted tool included questions on provider confidence, knowledge, attitudes and practices for quantitative analysis, as well as open-response questions that were analysed thematically. All GPs (n = 58) working within the area at the time of the study were invited to participate via emails and written letters distributed through practices and at pre-existing meetings, with 25 completing the survey (43% response rate).ResultsParticipants lacked knowledge around GP-facilitated disclosure of abuse, many believing the patient to be the main reason for non-disclosure. Half or fewer respondents indicated confidence in creating safety plans with patients, in making appropriate referrals and in identifying IPV/FV by history, signs and symptoms. There were mostly favourable attitudes towards asking about and assisting with IPV/FV, although only one quarter of respondents believed that individuals experiencing IPV/FV can make appropriate choices about how to handle their situation. In terms of practice, only one third agreed that they could match interventions to patient readiness to change. Other key concerns included difficulties in accessing timely support, with improved coordination of local services and systematic changes in the GP environment being the most common recommendations made by respondents.ConclusionsThis study demonstrated that the responding GPs in a regional area with high rates of IPV/FV have generally favourable attitudes towards identifying and assisting with IPV/FV but lack knowledge and confidence in the practical elements of enquiry. Surprisingly for a regional area, there was poor understanding of local support provision. The findings have the potential to meaningfully inform regional and rural primary care experiences, including desired educational opportunities and enhancing the relationship between health professionals and relevant community organisations. The results support the need for upstream changes in the general practice environment to improve the ability of regional and rural GPs to build relationships with patients over time and enhance overall health outcomes for those affected by abuse.

Quantitative Analysis of Mechanically Alloyed CuZrB Powders

Copper matrix composites are proving to be a suitable match for the present engineering needs of the market where higher temperature resistance and good microstructural stability are required. Powder metallurgy technique was used to procure the powder mixture, Cu-2Zr-0.6B (wt.%). Different mechanical alloying (MA) parameters were examined with the main focus on time, ranging from 10 h to 40 h. SEM analysis was employed to determine structural and morphological changes of the mechanically alloyed powder mixture. MIPAR image analysis software was used to complete the quantitative analysis of the mechanically alloyed CuZrB powders. Changes in size and shape of powder particles were determined during up to 40 h of MA with key points after every 10 h. It was concluded that the powder particle size decreases as the MA time increases. With the increase in MA time the area of each particle decreases due to the dominant plastic deformation mechanisms as particles undergo high forces through ball-particle-ball and wall-particle-ball collisions during the MA process.

A Corpus Stylistic Study of Foregrounded Language Patterns in the Climate Fiction Novel The Overstory

This study investigates foregrounded language patterns of Richard Power’s climate fiction novel The Overstory through a corpus stylistic framework, employing Geoffrey Leech’s(2008) method for quantitative analysis and qualitative methodologies of Gibbons & whitely (2018)and Leech & Short (2007). The research focuses on the identification and interpretation of foregrounded linguistic patterns. These foregrounded patterns enhance climate fiction's aesthetic and rhetorical impact and serve as a narrative strategy to engage readers with ecological concerns. By bridging literary stylistics and climate discourse, this study contributes to understanding how cli-fi functions as a vehicle for environmental advocacy and climate communication. The findings suggest that foregrounding climate fiction can awaken awareness and empathy, making it a vital tool for addressing contemporary ecological and environmental challenges.

Investigation of hydrogen sulfide adsorption using cavity ring-down spectroscopy

Abstract H2S is a toxic pollutant that threatens human health and industrial integrity by causing respiratory irritation, metal corrosion, and equipment damage. Accurate, real-time monitoring is critical due to strict emission regulations, but challenges persist in detecting low concentrations and addressing adsorption effects on material surfaces, complicating measurement accuracy. This study investigates the adsorption of H2S under continuous-flow conditions, examining various gas parameters and surface materials. Real-time monitoring of the adsorption process is performed using cavity ring-down spectroscopy for quantitative analysis, with absorption spectra in the range of 6335.9–6337.2 cm–1 employed to determine H2S concentrations. System performance is assessed through dynamic dilution measurements, reproducibility tests, and Allan variance analysis. The influences of the H2S concentration, gas flow rate, H2O content, and surface area on adsorption are also investigated. The results show that H2S adsorption increases with higher concentrations and larger surface areas but decreases with greater gas flow rates and H2O content. Furthermore, material analysis reveals that polymers and quartz adsorb less H2S than 304 stainless-steel, with polytetrafluoroethylene exhibiting the lowest adsorption. In conclusion, this study reveals that H2S adsorption varies with concentration, flow rate, surface area, and humidity. These insights aid in material selection and measurement optimization for accurate trace H2S detection.

Tumor-specific surface marker-independent targeting of tumors through nanotechnology and bioorthogonal glycochemistry.

Biological targeting is crucial for effective cancer treatment with reduced toxicity but is limited by the availability of tumor surface markers. To overcome this, we developed a nanoparticle-based, Tumor-specific suRfACE maRker-independent (TRACER) targeting approach. Utilizing the unique biodistribution properties of nanoparticles, we encapsulated Ac4ManNAz to selectively label tumors with azide reactive groups. Surprisingly, while NP-delivered Ac4ManNAz was cleared by the liver, it did not label macrophages, potentially reducing off-target effects. To exploit this tumor-specific labeling, we functionalized anti-4-1BB antibodies with dibenzocyclooctyne (DBCO) to target azide-labeled tumor cells and activate the immune response. In syngeneic B16F10 melanoma and orthotopic 4T1 breast cancer models, TRACER enhanced anti-4-1BB's therapeutic efficacy, increasing median survival time. Immunofluorescence analyses revealed increased tumor infiltration of CD8+ T and NK cells with TRACER. Importantly, TRACER reduced hepatotoxicity associated with anti-4-1BB, resulting in normal serum ALT and AST levels and decreased CD8+ T cell infiltration in the liver. Quantitative analysis confirmed a 4.5-fold higher tumor-to-liver ratio of anti-4-1BB accumulation with TRACER compared to conventional anti-4-1BB antibodies. Our work provides a promising approach for developing targeted cancer therapies that circumvent limitations imposed by the paucity of tumor-specific markers, potentially improving efficacy and reducing off-target effects to overcome liver toxicity associated with anti-4-1BB.

An Innovative Analytical Approach for Multi-Mycotoxin Detection in Craft Beer Using Freeze-Dried Samples, IAC Column and HPLC/ESI-MS/MS

The detection and quantification of mycotoxins in beer are critical for ensuring consumer safety and regulatory compliance. These contaminants, originating from barley and other grains, persist and potentially transform during the brewing process. This study presents an innovative analytical protocol using liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) for the simultaneous qualitative and quantitative analysis of nine mycotoxins, including aflatoxins (AFB1, AFB2, AFG1, AFG2), Ochratoxin A (OTA), Fumonisins (FB1, FB2), Deoxynivalenol (DON), and HT-2. The method leverages the efficiency of multi-mycotoxin immunoaffinity columns, providing streamlined sample preparation with high specificity and sensitivity. Validation was conducted using craft beers from Calabria, including freeze-dried samples to enhance analytical consistency and stability. The method’s accuracy was confirmed by using spiking samples with mycotoxins at concentrations compliant with the European Commission’s regulations (Recommendation 2024/1038/EU). The developed protocol delivers reliable results with minimized resource consumption, offering a robust tool for quality control and safety assessments in brewing. By addressing knowledge gaps in freeze-dried craft beer, this study contributes to advancing food safety standards in the brewing industry.

CONSUMER ENGAGEMENT IN FOOD WASTE REDUCTION IN THE FOOD SERVICE – SELECTED ASPECTS

This study aims to identify key areas of consumer involvement in reducing food waste in the food service sector, with particular emphasis on the use of mobile applications. The article presents theoretical considerations alongside a quantitative analysis of the studied issue, based on a survey conducted in April 2024 using the CAWI method among 301 residents of the Podkarpackie region. The empirical section focuses on assessing consumer engagement in food waste reduction at food service establishments through two well-known platforms available on the Polish market: Too Good To Go and Foodsi, which allow users to purchase unsold food at a reduced price at the end of the day. The findings indicate that awareness and utilization of such solutions are moderate among respondents, particularly concerning the Foodsi app. No significant differences were observed in app usage based on gender or age. However, women showed a higher tendency to request their uneaten meals to be packaged when dining out. Overall, only one in four respondents reported always asking for their leftovers to be packed at restaurants. In this context, the authors suggest that social campaigns, along with educational and communication initiatives, should be implemented to encourage both consumers and food service employees to adopt the habit of packaging uneaten meals in food service establishments.

Best Practices and Recommendations for Non-Liquid Matrices Bioanalysis

The analysis of Non-Liquid Matrices (NLMs) can provide key information on many aspects in drug discovery and development. These include but are not limited to drug uptake and distribution, engagement and modulation, and target exposure. A thorough understanding of these aspects is fundamental to the progression of drug development. In many cases, such an understanding can only be achieved through quantitative analysis of NLMs. Such dependence can lead to bottlenecks in the drug development process—as the practices and regulations that govern bioanalysis of conventional liquid matrices typically cannot be directly applied to NLMs. This paper strives to fill this crucial gap. To this end, subject matter experts from across the industry, through the auspices of the AAPS Bioanalytical Community, have combined their collective best practices for NLM bioanalysis in this paper. Certainly, this endeavor came with challenges, the most prominent of which also serves as the impetus for this project, the lack of literature on NLM bioanalysis dealing with different types of NLM, analysis rigor, and best practices to draw from. This paper aims to serve as a comprehensive set of best practices drawn from the experiences of leading scientists across the industry—for NLM bioanalysis in drug development.Graphical

Lexical Creativity in Online Music Reviews

The language of the 21st century encompasses a wide array of texts, many of which can be found on the Internet. While the language of Internet blogs, posts and memes has received considerable attention from scholars, the language of online music reviews remains one of the most underresearched Internet genres. One of the music reviewing websites offering lexically creative content is Pitchfork. Authors of the reviews are prolific with regard to the creation of hyphenated neologistic compounds such as all-proceeds-to-charity wine, the last-real-gangsta-standing attitude and smartphone-sucking lives. The aim of this study is to analyse hyphenated compound occasionalisms and neologisms in Pitchfork music reviews in terms of their meaning, structure and function. The analysis features compounds obtained from the corpus of music reviews created for the purpose of the study. Quantitative analysis involves all compounds in the reviews, while qualitative analysis is employed for neologistic compounds. The findings indicate that two-element compounds are the most common in the corpus as far as compound structure is concerned. In terms of the syntactic criterion, compound adjectives are the most frequently used, followed by compound nouns, with few instances of compound verbs and adverbs. Neologistic compounds are employed for the purposes of ludic wordplay as well as achieving humour and irony. The most salient features of neologistic compounds are high context-dependence, unpredictability and allusions to pop-culture.

Assessing the efficacy of nonsurgical periodontal treatment on rheumatoid arthritis: an umbrella review.

The relationship between periodontitis and rheumatoid arthritis (RA) has attracted considerable interest. However, the effect of non-surgical periodontal treatment (NSPT) on RA remains uncertain. This umbrella review aims to consolidate current research to establish a stronger evidence base. Medline, Embase, and the Cochrane library were searched from inception to August 2024. Two independent reviewers handled study selection, data extraction, and quality assessment (AMSTAR-2). The qualitative analysis covered clinical activity, joint symptoms, inflammatory markers, cytokines, and autoantibodies. Quantitative results for disease activity score 28 (DAS28), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were reported as mean differences (MD)with 95% confidence intervals (CI). A total of 2,982 records were screened, with 41 full-text articles assessed for eligibility, and9 selected for evidence synthesis. Qualitative analysis suggests that NSPT may reduce clinical activityin patients with periodontitis and RA. Quantitative analysis provided suggestive evidence on theeffects of NSPT on DAS28, with the MD ranging from -0.38 (95% CI: -0.46 to -0.31) to -1.18 (95%CI: -1.43 to -0.93). One-third of the included studies were rated as "high" quality, while another one-third were "critically low". The present evidence suggests that NSPT may provide benefits in managing RAsymptoms in patients with periodontitis; however, the potential bias of current evidence calls forfurther rigorous studies. Clinicians should account for the complex interplay between periodontitis andRA when devising treatment strategies.

A comparative study on monologic vs. dialogic technology-mediated feedback modalities: Students’ uptake and perspectives

Investigating how learners incorporate feedback into drafts is crucial, as feedback alone does not ensure effective implementation. Writing instructors can offer technology-mediated feedback rather than traditional methods, a practice supported by current research, for managing feedback processes and improving uptake. Consequently, this study compares screencast feedback (monologic) and online one-on-one video conference feedback (dialogic) on literature reviews (LRs) of 10 students in an L2 academic writing class. Over five weeks, half the students received one-on-one video conference feedback for their first draft and screencast feedback for the second draft, while the others received feedback in reverse order and then revised their drafts. Quantitative analysis showed a significant success rate difference favoring one-on-one video conference feedback, confirmed by Chi-square tests. This feedback was especially effective in content clarity, content development, cohesion, and coherence. Qualitative student interviews revealed the usefulness of both feedback types, with one-on-one video conference feedback proving superior for communication and comprehension. Findings suggest there may be some efficiencies if instructors could incorporate both types yet save more time-consuming, effortful modalities (one-on-one) to address vital issues. Hence, language instructors should consider these approaches as complementary rather than competing technology tools.

Noncontact optical 3D strain measurements in cervical soft tissues biomechanics by digital image correlation under tensile test: an experimental approach

BackgroundDigital image correlation (DIC) is widely used to measure surface strain in loaded objects. When studying the deformation of the cervical spine, the complexity and non-planarity of the structure complicate the speckle pattern required for applying DIC. While this non-invasive technique has shown promise in biomechanical testing, its application to cervical spine analysis presents unique challenges, particularly in achieving dynamic full-scale multi-aspect strain measurements. The aim of this paper is to introduce a method for exploring the stress-strain relationship on cervical cadaveric specimen by optical non-contact measurement system.MethodCervical cadaveric specimens were selected as subjects. Before testing, anatomical exposure, embedding, and spraying were performed sequentially. Specimen preparation was optimized through transverse process removal to enhance visualization of key anatomical structures. The surface strain under tensile testing was analyzed by the Aramis non-contact measurement system.ResultHigh-quality three-dimensional strain images were obtained with improved inspection points across all aspects, particularly in the lateral aspect (5397.25 ± 723.76 vs. 3268.25 ± 573.17, P < 0.05). Under 60N tensile loading, strain distribution revealed concentration in soft tissue regions while preserving clear visualization of vertebral bodies, intervertebral discs, and foramina. Quantitative analysis shown consistent deformation patterns across cervical segments (C4-C7), with no significant differences in segmental parameters (P > 0.05).ConclusionThe application of an optical non-contact measurement system in this study of cervical spine biomechanics has been proven effective. This method potentially mitigates some of the limitations associated with previous DIC techniques when applied to cervical cadaveric specimens. As a result, it enables more available measurements of multidimensional strain, which may enhance our understanding of the mechanics of the cervical spine.

Quantitative Detection of Orthotopic Liver Cancer in Mice Using Indocyanine Green and Dynamic Diffuse Fluorescence Tomography Imaging

ABSTRACTOrthotopic tumor model has become an essential tool for studying drug biodistribution and tumor progression over time owing to the rapid development of in vivo imaging and immunological science. Dynamic diffuse fluorescence tomography (DFT) is a promising imaging modality that can map the three‐dimensional distribution of a fluorophore within the object and capture the metabolic parameters of fluorophores in vivo. It has been widely applied in tumor detection, drug development, and efficacy evaluation. To detect orthotopic liver tumors, we combined indocyanine green (ICG) and a DFT system to perform fluorescence imaging and quantitative analysis for orthotopic liver tumors in mice. The orthotopic liver models were first established, and the liver fluorescence yields were detected in pre‐ and post‐cancerous liver using the DFT system. The results showed that there was higher liver uptake and prolonged retention in orthotopic tumor liver compared to normal liver. Furthermore, the pharmacokinetic parameters suggested the uptake coefficient of tumor liver was above twice that of normal liver, while the excretion rates were similar. Additionally, to intuitively assess tumor occurrence, we propose using normalized fluorescence ratios of 5 and maximum fluorescence values of 0.01 mm−1 as evaluation criteria. The study demonstrates DFT imaging is a promising tool in orthotopic tumor model detection and drug or agent metabolic evaluation.

Binding Sites of a PET Ligand in Tau Fibrils with the Alzheimer's Disease Fold from 19F and 13C Solid-State NMR.

Aggregation of the tau protein into cross-β amyloid fibrils is a hallmark of Alzheimer's disease (AD) and many other neurodegenerative disorders. Developing small molecules that bind these tau fibrils is important for the diagnosis and treatment of tauopathies. Here, we report the binding sites of a positron emission tomography (PET) ligand, PI-2620, to a recombinant tau construct that adopts the C-shaped AD fold. Using solid-state NMR 13C-19F rotational-echo double-resonance (REDOR) experiments, we measured the proximity of protein residues to the fluorine atom of the ligand. These data indicate that PI-2620 binds at two main locations in the concave interior of the C-shaped structure. Molecular docking simulations constrained by these REDOR data identified five binding poses at these two locations. In addition, 2D 13C-13C correlation NMR spectra indicate that PI-2620 decreased the intensities of residues at the protofilament interfaces, indicating that the ligand disordered the filament packing. Quantitative analysis of the 19F NMR spectra indicates that PI-2620 binds these AD-fold tau fibrils with a stoichiometry of ∼20 mol %, in which 10 mol % are immobilized and the rest are mobile. These results provide experimental constraints to the interaction of this second-generation PET tracer with tau fibrils adopting the AD fold and should be useful for the development of future imaging agents with improved stoichiometry and specificity for AD tau.