Total Correlation Research Articles

The Posterior Shoulder Instability Questionnaire: internal consistency, content and criterion validity, responsiveness, and reliability of a new tool for the assessment of posterior shoulder instability

Posterior shoulder instability (PSI) is an increasingly recognized cause of shoulder dysfunction particularly in young active patients and certain athlete populations. When evaluating the efficacy of treatment for PSI, specific outcome measures for this population are essential. The aim of the current research was to describe the development and evaluation of a patient reported outcome measure (PROM) specific for PSI. A retrospective cohort study design of patients with PSI was used to develop and evaluate the "Posterior Shoulder Instability Questionnaire (PSI-Q)". Items for PSI-Q were generated through an expert focus group and existing questionnaires. Preliminary data analysis identified redundancy of items and resulted in the PSI-Q being refined. The final PSI-Q was evaluated on 128 patients with PSI with a structural lesion requiring surgical intervention. Participants were excluded in the absence of a posterior glenohumeral joint lesion. Internal consistency (Cronbach α and corrected item-total correlation), content validity, criterion validity, responsiveness, and test-retest reliability (intraclass correlation coefficient; ICC) were examined. Content validity, criterion validity and responsiveness were compared with the Melbourne Instability Shoulder Score (MISS) and the Western Ontario Shoulder Index (WOSI). The minimum detectable change score (MDC) was calculated. The Cronbach α for the total scale pre and post-intervention was high (α = 0.97). All five domains (Pain, Instability/Weakness/Stiffness, Function, Occupation and Sport, and Quality of Life and Satisfaction) demonstrated acceptable internal consistency for each subsection and the overall score of the scale (α > 0.70). The corrected-item total correlation for each domain were within an acceptable range. The responsiveness of the PSI-Q questionnaire was excellent (effect size, 2.06; standard response mean, 1.34) and was higher than the MISS and WOSI. There were no relevant floor effects and one ceiling effect. Reliability was excellent (ICC (1,1) = 0.93) and the calculated MDC was 10.9 points. This study designed and validated a questionnaire specific for measuring symptoms and function in people with structural PSI requiring surgery. The PSI-Q demonstrates good measurement properties and provides an MDC that is useful for researchers and clinicians. In structural PSI, the PSI-Q has a higher responsiveness and more accurately reflects a patient's overall perceived shoulder status compared to current patient reported outcomes for shoulder instability. The psychometric properties of the PSI-Q are still to be determined in a non-surgical population.

On a conjecture concerning the Fisher–Widom line and the line of vanishing excess isothermal compressibility in simple fluids

In the statistical mechanics approach to liquid-state theory, understanding the role of the intermolecular potential in determining thermodynamic and structural properties is crucial. The Fisher–Widom (FW) line, which separates regions in the temperature vs density plane where the decay of the total correlation function is monotonic or oscillatory, provides insights into the dominance of the attractive or repulsive part of the interactions. Stopper et al. have recently conjectured [J. Chem. Phys. 151, 014501 (2019)] that the line of vanishing excess isothermal compressibility approximates the FW line in simple fluids. Here, we investigate this conjecture using the Jagla potential and also explore the line of vanishing excess pressure. We employ theoretical approximations and Monte Carlo simulations to study one-dimensional and three-dimensional systems. While exact results for the one-dimensional case do not support the conjecture, our Monte Carlo simulations for the three-dimensional fluid validate it. Our findings not only contribute to the understanding of the relationship between the three transition lines but also provide valuable insights into the thermodynamic and structural behaviour of simple fluids.

Pedestrians’ Urban Space Preference Scale: A Study on Reliability and Validity

ABSTRACT This study develops a valid and reliable scale for the spatial preferences of pedestrians in public spaces. The study was conducted in 2023 and includes the development of a model based on survey results. With the help of random sampling method, the research was carried out with 401 random participants who were currently walking in the urban space. The scale development process started with an initial pool of 34 items determined from the literature on the subject. The data obtained from the applied scale were subjected to total item correlation, exploratory and confirmatory factor analyses and reliability analyses. According to the results of the analyses, it was found that the scale consisted of 19 items and 5 factors, the variance rate explaining the whole scale was 62.8%, and the fit index values were acceptable. Cronbach alpha internal consistency reliability coefficient was calculated as 0.813.

Adaptation of the Student Attitudes Toward Artificial Intelligence Scale to the Turkish Context: Validity and Reliability Study

This study aimed to adapt the Student Attitudes toward Artificial Intelligence (SATAI) Scale to the Turkish Context both at secondary and high school levels. The research was conducted with two study groups: the first group of 384 secondary school students and the second group of 295 high school students. Data were collected from these participants in the 2023–2024 academic year. The scale consists of 26 items and three factors; behavioral, affective, and cognitive, and serves the purpose of measuring the students’ attitude toward artificial intelligence. The behavioral factor assesses students’ AI-related actions while the affective factor captures their emotional reactions, and the cognitive factor, in turn, evaluates their knowledge of the topic at hand. By determining students’ attitudes about AI, this measurement guides learning processes, contributes to the development of teaching materials, and increases interest in the field of AI. Language validity, construct validity, criterion validity, conceptual and experiential equivalence, and reliability studies were carried out in the process of adapting the scale to Turkish. To ensure the language validity of the Turkish form of the scale, translation back translation technique was applied and expert opinions were sought. Confirmatory Factor Analysis (CFA) was applied to test the construct validity. To test the criterion validity, the correlation between the whole scale and each sub-factor was examined. Within the scope of reliability studies, Cronbach Alpha reliability coefficients of the scale, half-test reliability, item total correlations, and item discrimination values were calculated. As a result of the research, it has been determined that the Student Attitudes toward Artificial Intelligence (SATAI) Scale Turkish Form is a valid and reliable assessment tool.

Preferential Solvation Phenomena as Solute-Induced Structure-Making/Breaking Processes: Linking Thermodynamic Preferential Interaction Parameters to Fundamental Structure Making/Breaking Functions.

In this work, we identify the explicit macroscopic-to-microscopic rigorous links between existing thermodynamic preferential interaction parameters and microstructural descriptors based on total correlation function integrals, leading to their unambiguous characterization in terms of fundamental structure making/breaking functions . First, we provide the statistics mechanical framework to identify a universal molecular-based signature for the preferential solvation phenomenon involving solutes at infinite dilution in mixed-solvent environments and discuss its fundamental properties. Then, we characterize the functions relevant to the process, identify the microscopic markers for the existing preferential interaction parameters in terms of the functions, and test their compliance with a pair of essential microstructural constraints linked to the properties of the universal signature. Moreover, we illustrate the analysis by probing the behavior of a representative ternary system comprising the solubility of methane in aqueous 1,4-dioxane mixed-solvent environments under ambient conditions. Finally, we discuss some relevant issues surrounding the statistical mechanical (microstructural) interpretation of the thermodynamic (macroscopic) preferential interaction parameters, review some pitfalls in their evaluation from molecular simulation, and provide an outlook.

Developing a Toolkit to Measure the Impact of Programme Assessment Result on Improving the Teaching Quality

This study aimed to develop a valid and reliable toolkit to measure the impact of external assessment results and improve teaching activities in engineering majors at Vietnamese universities. The study comprised two stages: development and testing of the questionaire. In addition to desk research, expert interviews were conducted with six education quality assurance specialists to assess the content and construct validity of a several items intended to gauge the impact of external assessment results on improving teaching activities in the questionaire. Simultaneously, SPSS 26.0 software was employed to ensure the validity and reliability of the scale following the testing phase involving sample 439 lecturers teaching engineering majors. The research findings indicated that Cronbach's alpha coefficients were above 0.7, and 38 out of 40 questions exhibited a total variable correlation of over 0.03, thereby ensuring the reliability of the scale. Furthermore, the development of this scale is poised to furnish valuable data for improving teaching activities at the higher education institutions.

Identify Attributes of Service Quality Factors and Other Factors Affecting Calla SPA Customer Satisfaction

This research aimed to identify the factors influencing customer satisfaction at Calla SPA, focusing on service quality attributes such as Tangibility, Reliability, Ability to meet expectations, and Assurance, as well as other factors like price and location of Calla SPA offices. Both qualitative and quantitative methods were utilized, including document research, in-depth interviews, group discussions, and surveys. Results indicated that service quality (β3) had the strongest impact on satisfaction, followed by price (β1) and location of the SPA (β2). SPSS testing confirmed the reliability of the scale (α = 0.70 to 0.95), with total correlation coefficients above 0.3, KMO values between 0.5 and 1, and significance levels (Sig) below 0.05. These findings provide a foundation for Calla SPA's management to enhance customer satisfaction through service quality improvements, thereby aiding in market share retention, market expansion, and revenue growth. Furthermore, the research contributes to the theoretical understanding of service quality and customer satisfaction within the SPA industry

Relaxation Editing in NMR Using a New Two-Dimensional Long-Lived Coherence Method for Mixture Analysis.

The exploration of metabolomics and targeted segments of proteins stands as a pivotal facet of Nuclear Magnetic Resonance (NMR) analysis, furnishing valuable insights into molecular architectures and potential therapeutic applications. The issue of spectral congestion frequently presents challenges in ascribing distinct peaks within the confines of both one-dimensional (1D) and two-dimensional (2D) NMR spectra. Numerous strategies have been proposed to resolve specific resonances in NMR spectra differentially. Among these approaches, relaxation editing emerges as a viable solution. In the realm of relaxation phenomena within NMR, Long-Lived States (LLS) and Long-Lived Coherences (LLC) manifest as promising phenomena, offering enhanced relaxation lifetimes in comparison to the traditional longitudinal (T1) and transverse (T2) relaxation times for coupled nuclear spins. Notably, LLC presents a pathway to attenuate uncoupled high-intensity peaks, effectively diminishing their impact. The foundation of this technique rests upon the premise that the relaxation lifetime in the rotating frame (T1ρ) remains smaller than TLLC. In pursuit of refining spectral assignments within complex mixtures, we introduce a new pulse sequence tailored for LLC Total Correlation Spectroscopy (LLC-TOCSY). This demonstrates efficacy in extracting LLC signals within configurations involving multiple coupled spins, thereby decluttering the spectrum and enhancing the accuracy of peak assignments. To validate the effectiveness of this method, a collection of samples was subjected to scrutiny, yielding compelling results.

Developing the first Arabic quality of life for parents of children with autism (QoLA) scale: translation, cultural adaptation and psychometric validation

PurposeIn this research, the first Arabic quality of life (A-QoLA) measure for the mothers and fathers of children with autism is translated and validated. While there have been several translations of the QoLA scale, to the best of our knowledge, there are no Arabic version of this scale.MethodTo translate and validate the QoLA, 407 family members (mostly parents) participated in this research. Item total correlation and confirmatory factor analysis (CFA) were used for the scale validation process.ResultsThe results show that like QoLA, all the items in Part A of the A-QoLA were positively correlated with the total score except items 2, 4, 17, and 22 (which were deleted). In addition, the Part B outcome of the item total correlation showed that all the items had a positive correlation with the overall score. The CFA results show high internal validity and consistency confirmed the two-domain structure for QoLA after it was translated into Arabic.ConclusionOur results have very important implications as autism is quite common in the Arab world, and the scale can be used across several Arabic-speaking countries to understand the impact of autism on families.

Damage effect evaluation of CCD irradiated by laser based on multi-source information fusion

This study introduces an advanced approach for assessing the damage state of charge-coupled devices (CCDs) caused by laser interactions, leveraging a multi-source and multi-feature information fusion technique. We established an experimental system that simulates laser damage on CCDs and collects diverse data types including echo information from active laser detection based on the ‘cat's eye’ effect, plasma flash data, and surface image characteristics of the CCD. A probabilistic neural network (PNN) was utilized to integrate these data sources effectively. Our analysis demonstrated that using multiple features from single sources significantly improves the accuracy of the damage assessment compared to single-feature evaluations. The error rates using dual features from each information type were 10.65% for cat's eye echo, 7.3% for plasma flash, and 7.17% for surface image analysis. By combining all three information sources and six features, we successfully reduced the error rate to 0.85%, with the evaluation time under 60 milliseconds. These findings confirm that our multi-source, multi-feature fusion method is highly effective for the online and real-time evaluation of CCD damage, offering significant improvements in the operational reliability and safety of devices in high-energy environments.

Psychometric Properties of the Chinese Version of Multidimensional Scale of Perceived Social Support.

The purpose of this study is to revise the Multidimensional Scale of Perceived Social Support and validate the reliability and validity of the Chinese version of the scale for Chinese college students. A total of 2830 Chinese college students were tested with the Chinese version of MSPSS. Four weeks after the formal test, 80 randomly selected subjects were retested. The item analysis shows that the total correlation between each item and the total score is 0.525~0.806, higher than the standard of 0.30; the difference between the high group and the low group in all items has reached the significant level. Exploratory factor analysis shows that the scale includes three factors with a cumulative contribution rate of 69.185%; confirmatory factor analysis shows that the data is well fitted. The total score and three factors of social support scale are positively correlated with self-esteem, with a correlation value of 0.367~0.433, and negatively correlated with depression and anxiety, with correlation values of -0.356~-0.428 and -0.253~-0.308; all are significant at 0.01 level. The internal consistency coefficient of the scale is 0.911, the split-half coefficient is 0.865, and the test-retest coefficient is 0.837-0.914. The Chinese version of the MSPSS has good reliability and validity, and is suitable for Chinese college students.

Using Discourse Markers to Enhance Students’ Speaking Skills

English proficiency is a desirable performance quality. The aim of this study is to determine the effectiveness of discourse markers in improving English speaking skills. This study employs a quantitative methodology. This study employed a pre-test-posttest group design, The study's demographic and sample consist of Class XI IPA 80 students from the academic year 2023/2024. The researcher employed the snowball sampling method to ascertain the requisite sample size. Prior to conducting the pre and post tests, the researcher assessed the instrument's validity and reliability using SPSS. This was done by examining the scores on the corrected item total correlation, which measures the correlation between item scores and the total item score. The students were designated as Group A (experimental) and Group B (control). Subsequently, students engage in a Pretest to ascertain any disparities among them. The researcher provided discourse markers to both groups; however, only the experimental group employed them, whilst the control group did not. The experimental group will receive treatment including the use of discourse markers. The T test was employed as the data analysis tool. The results indicated that the observed T value was 7.313, and the Sig. value was less than 0.05. Therefore, it can be inferred that the utilisation of discourse markers enables students to enhance their proficiency in English speaking. This research is significant as it can enhance English language acquisition, particularly by highlighting the significance of teachers' role in teaching discourse markers during English language learning.

Feedback and Galaxy Dynamics: A Study of Turbulence and Star Formation in 34 Galaxies Using the PHANGS Survey

The correlation between interstellar turbulent speed and local star formation rate surface density, ΣSFR, is studied using CO observations in the PHANGS survey. The local velocity dispersion of molecular gas, σ, increases with ΣSFR, but the virial parameter, α vir, is about constant, suggesting the molecular gas remains self-gravitating. The correlation arises because σ depends on the molecular surface density, Σmol, and object cloud mass, M mol, with the usual molecular cloud correlations, while ΣSFR increases with both of these quantities because of a nearly constant star formation efficiency for CO. Pressure fluctuations with ΔΣSFR are also examined. Azimuthal variations of molecular pressure, ΔP mol, have a weaker correlation with ΔΣSFR than expected from the power-law correlation between the total quantities, suggesting slightly enhanced star formation rate (SFR) efficiency per molecule in spiral arms. Dynamical equilibrium pressure and SFR correlate well for the whole sample, as PDE∝ΣSFR1.3 , which is steeper than in other studies. The azimuthal fluctuations, ΔP DE(ΔΣSFR), follow the total correlation P DE(ΣSFR) closely, hinting that some of this correlation may be a precursor to star formation, rather than a reaction. Galactic dynamical processes correlate linearly such that ΣSFR∝(ΣgasR)1.0±0.3 for total gas surface density Σgas and galactic dynamical rates, R, equal to κ, A, or Ω, representing epicyclic frequency, shear rate A, and orbit rate Ω. These results suggest important roles for both feedback and galactic dynamics.

ИНДЕКС ФОНДООТДАЧИ: СОВРЕМЕННОЕ СОСТОЯНИЕ И ФАКТОРЫ РОСТА

The scientific article contains an analysis of scientific literature on ensuring the efficient use of fixed assets in enterprises, research on capital productivity and capital intensity, and the development of main directions for the efficient use of fixed capital. The dynamics of the coefficients of renewal and disposal of fixed assets in the economy are presented in graphical form. The information base for the study was data from the official website of the Federal State Statistics Service. The maximum values of the renewal coefficient were observed in 2018, 2019 and 2022, and the minimum in 2015, 2020 and 2021. The maximum values of the retirement rate are presented in 2014, 2015 and 2016, and the minimum in 2019, 2020 and 2021. An econometric study of the capital productivity index showed an inverse and very weak relationship with the value of gross domestic product and the cost of fixed assets (the value of the correlation coefficient (index) (-0.1)): with an increase in the value of gross domestic product and the value of fixed assets in the period under study, no growth was observed capital productivity index. The value of the gross domestic product and the cost of fixed assets have a direct and close relationship (the value of the correlation coefficient (index) is 0.9): the annual growth of the gross domestic product is accompanied by an increase in the cost of fixed assets. A matrix of correlation coefficients (indices) was constructed to calculate the total correlation coefficient (index). The result of calculating the total correlation coefficient (index) (its value is 0.4) showed that there is a direct and weak connection between the capital productivity index, the value of the gross domestic product and the cost of fixed assets: the growth of the capital productivity index is weakly related to the growth of the gross domestic product and the cost of fixed assets funds.

Transforming Landslide Prediction: A Novel Approach Combining Numerical Methods and Advanced Correlation Analysis in Slope Stability Investigation

Landslides cause significant economic losses and casualties worldwide. However, robust prediction remains challenging due to the complexity of geological factors contributing to slope stability. Advanced correlation analysis methods can improve prediction capabilities. This study aimed to develop a novel landslide prediction approach that combines numerical modeling and correlation analysis (Spearman rho and Kendall tau) to improve displacement-based failure prediction. Simulations generate multi-location displacement data sets on soil and rock slopes under incremental stability reductions. Targeted monitoring points profile local displacement responses. Statistical analyses, including mean/variance and Spearman/Kendall correlations, quantified displacement-stability relationships. For the homogeneous soil slope, monitoring point 2 of the middle section of the slope showed a mean horizontal displacement of 17.65 mm and a mean vertical displacement of 9.72 mm under stability reduction. Spearman’s rho correlation coefficients ranged from 0.31 to 0.76, while Kendall’s tau values ranged from 0.29 to 0.64, indicating variable displacement–stability relationships. The joint rock slope model had strong positive total displacement correlations (Spearman’s and Kendall’s correlation ranges of +1.0 and −1.0) at most points. Horizontal and vertical displacements reached mean maxima of 44.13 mm and 22.17 mm, respectively, at the unstable point 2 of the center section of the slope. The advanced correlation analysis techniques provided superior identification of parameters affecting slope stability compared to standard methods. The generated predictive model dramatically improves landslide prediction capability, allowing preventive measures to be taken to mitigate future losses through this new approach.

Adaptation of the Environmental Worry Index into Turkish: A Validity and Reliability Study on Teacher Candidates

Purpose: In the present research, it was aimed to adapt the Environmental Worry Index (EWI) developed by Oguntayo et al. (2023) into Turkish. Methodology: The study was conducted with the participation of 508 teacher candidates. Exploratory graph analysis (EGA), exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were performed for the validity studies. The reliability of the measurements collected via the Turkish form of the scale was examined via the Cronbach's alpha internal consistency coefficient. Corrected item total correlations were calculated for item discrimination, and Ferguson Delta was computed to provide a discrimination index for the entire scale. Findings: The EGA outputs and the results of parallel analysis run within the scope of EFA revealed a single-factor structure unlike the two-dimensional original form of the scale. In EFA, the variance explained for the single-factor solution was determined as 45.80% and the factor loadings ranged between .44 and .80. The CFA results showed that the fit indices for the unidimensional model were within the recommended limits and the factor loadings of the items varied between .41 and .71. Cronbach’s alpha coefficient was estimated as .84 and corrected item total correlations ranged between .36 and .62. The Ferguson’s delta statistic, on the other hand, was found to be .95. Highlights: The results obtained provide evidence that the measurements collected through the Turkish form of the EWI have adequate psychometric properties.

Psychometric Properties of the Turkish Version of the Emotion Efficacy Scale – 2 in a Sample of Turkish Emerging Adults

This study sought to evaluate the psychometric properties of the Turkish version of the Emotion Efficacy Scale – 2 (EES2) among 763 emerging adults. To examine the factor structure of the Turkish version of the EES2, an exploratory factor analysis (EFA) and a confirmatory factor analysis (CFA) were conducted. EFA revealed a one-factor solution. After implementing some modifications, CFA of the one-factor structure demonstrated adequate model fit indices and good internal consistencies. Two items were removed from the scale due to a low factor loading and a low item total correlation coefficient. Correlational analyses supported the criterion validity of the Turkish EES2 with relations to emotion regulation difficulties, acceptance and action, and valued action in expected directions. Furthermore, test-retest reliability indicated good reliability of the scale. Overall, the results revealed that the 8-item Turkish EES2 is a promising measurement tool that can be used by researchers and mental health practitioners.

Identifying gene expression programs in single-cell RNA-seq data using linear correlation explanation

ObjectiveGene expression analysis through single-cell RNA sequencing (scRNA-seq) has revolutionized our understanding of gene regulation in diverse cell types, tissues, and organisms. While existing methods primarily focus on identifying cell type-specific gene expression programs (GEPs), the characterization of GEPs associated with biological processes and stimuli responses remains limited. In this study, we aim to infer biologically meaningful GEPs that are associated with both cellular phenotypes and activity programs directly from scRNA-seq data. MethodsWe applied linear CorEx, a machine-learning-based approach, to infer GEPs by grouping genes based on total correlation optimization function in simulated and real-world scRNA-seq datasets. Additionally, we utilized a transfer learning approach to project CorEx-inferred GEPs to other scRNA-seq datasets. ResultsBy leveraging total correlation optimization, linear CorEx groups genes and demonstrates superior performance in identifying cell types and activity programs compared to similar methods using simulated data. Furthermore, we apply this same approach to real-world scRNA-seq data from the mouse dentate gyrus and embryonic colon development, uncovering biologically relevant GEPs related to cell types, developmental ages, and cell cycle programs. We also demonstrate the potential for transfer learning by evaluating similar datasets, showcasing the cross-species sensitivity of linear CorEx. ConclusionOur findings validate linear CorEx as a valuable tool for comprehensively analyzing complex signals in scRNA-seq data, leading to deeper insights into gene expression dynamics, cellular heterogeneity, and regulatory mechanisms.

Evaluating Wastewater Quality Parameters as an Alternative or Complement to Molecular Indicators for Normalization during SARS-CoV-2 Wastewater-Based Epidemiology

Measuring fecal nucleic acid indicators for data normalization can increase costs during wastewater-based epidemiology (WBE). The efficacy of routinely assayed water quality parameters was assessed as an alternative or complement to fecal nucleic acid viral indicator data for their utility in adjusting measured SARS-CoV-2 gene concentrations to improve the relationship between wastewater molecular data and clinical COVID-19 case data. This research covers two study designs: grab samples collected from sewers serving The Ohio State University campus and composite influent samples collected at five wastewater treatment plants (WWTPs) across the state of Ohio. Weekly mandatory clinical testing was used to monitor infections in the student population, and statewide cases were reported through voluntary clinical testing. Statewide WWTP results showed significant strong correlation between SARS-CoV-2 concentrations in the wastewater and confirmed COVID-19 cases, and correlation increased when normalized by flow and additionally increased when normalized by pH, total suspended solids, and temperature, but correlation decreased when normalized by a nucleic acid fecal viral indicator (PMMoV). On campus, correlations were generally not significant unless normalized by PMMoV and/or UV absorbance parameters. Because water quality parameters are routinely assayed at wastewater treatment plants and some may be collected by autosamplers, incorporating wastewater quality data may improve WBE models and could minimize molecular and cellular testing for fecal indicators to decrease costs.

A convenient method for the relative and absolute quantification of lipid components in liposomes by 1H- and 31P NMR-spectroscopy

ObjectiveLiposomes are promising delivery systems for pharmaceutical applications and have been used in medicine in the recent past. Preparation of liposomes requires reliable characterization and quantification of the phospholipid components for which the traditional cumbersome molybdate method is used frequently. The objective was to improve relative and absolute quantification of lipid components from liposomes. MethodsA reliable method for quantification of lipid composition in liposome formulations in the 1–10 μmol range with 1H- and 31P NMR spectroscopy at 600 MHz has been developed. The method is based on three crystalline small-molecule standards (Ph3PO4, (Tol)3PO4, and Ph3PO) in CDCl3. ResultsExcellent calibration linearity and chemical stability of the standards was observed. The method was tested in blind fashion on liposomes containing POPC, PEG-ceramide and a pH-sensitive trans-aminocyclohexanol-based amphiphile (TACH).11Et3PO4 Triethyl phosphate, Ph3PO4 triphenyl phosphate, (Tol)3PO4 tritolyl phosphate, Ph3PO triphenylphosphine oxide, POPC 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine, DPPC 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DOPC 1,2-dioleyl-sn-glycero-3-phosphocholine, DOPE 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine, POPE 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine, PEG-ceramide N-palmitoyl-sphingosine-1-(succinyl[methoxy(polyethylene glycol)2000]), COSY correlation spectroscopy, TOCSY total correlation spectroscopy, HMBC heteronuclear multiple-bond correlation, TACH trans-aminocyclohexanol, ANTS 8-aminonaphthalene-1,3,6-trisulfonic acid, disodium salt, DPX p-xylene-bis-pyridinium bromide, HEPES 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid, pfg pulse-field gradient. Relative quantification (percentage of components) as well as determination of absolute lipid amount was possible with excellent reproducibility with an average error of 5%. Quantification (triplicate) was accomplished in 15 min based on 1H NMR and in 1 h based on 31P NMR. Very little change in mixture composition was observed over multiple preparative steps. ConclusionLiposome preparations containing POPC, POPE, DOPC, DPPC, TACH, and PEG-ceramide can be reliably characterized and quantified by 1H NMR and 31P NMR spectroscopy at 600 MHz in the μmol range.