Controlling Extraction of Rare Earth Elements Using Functionalized Aryl-vinyl Phosphonic Acid Esters.

Ligands that can discriminate between individual rare earth elements are important for production of these critical elements. A set of aryl-vinyl phosphonic acid ligands for extracting rare earth elements were designed and synthesized under the hypothesis that the strength of the rare earth-ligand interactions could be tuned by changing the dipole moment of the ligand. The ligands were synthesized via a two-step reaction procedure using a Heck coupling reaction to functionalize vinyl phosphonic acid, followed by Steglich esterification to obtain high-purity styryl phosphonic acid monoesters with varying dipole moments along the P-C bond. The metal binding strength and composition of the rare earth complexes formed with these styryl phosphonic acid monoesters were experimentally studied by liquid-liquid extraction techniques, while DFT calculations were performed to determine the dipole moments of the free and complexed ligands and the electronic structure of the complexes formed. All three prepared ligands were much stronger extracting agents for europium(III) than the dialkylphosphonic acids usually used for this separation. However, the order of increasing extraction strength was found to match the order of the decreasing calculated dipole moment along the P-C bond of the three styryl-based ligands, rather than correlating with increasing ligand basicity, as reflected by the pKa of the ligands. These findings suggest that this approach can be used to systematically alter the extraction strength of aromatic phosphonic monoesters for rare earth element purification.

Mediating Photochemical Reaction Rates at Lewis Acidic Rare Earths by Selective Energy Loss to 4f-Electron States.

Manifesting chemical differences in individual rare earth (RE) element complexes is challenging due to the similar sizes of the tripositive cations and the corelike 4f shell. We disclose a new strategy for differentiating between similarly sized Dy3+ and Y3+ ions through a tailored photochemical reaction of their isostructural complexes in which the f-electron states of Dy3+ act as an energy sink. Complexes RE(hfac)3(NMMO)2 (RE = Dy (2-Dy) and Y (2-Y), hfac = hexafluoroacetylacetonate, and NMMO = N-methylmorpholine-N-oxide) showed variable rates of oxygen atom transfer (OAT) to triphenylphosphine under ultraviolet (UV) irradiation, as monitored by 1H and 19F NMR spectroscopies. Ultrafast transient absorption spectroscopy (TAS) identified the excited state(s) responsible for the photochemical OAT reaction or lack thereof. Competing sensitization pathways leading to excited-state deactivation in 2-Dy through energy transfer to the 4f electron manifold ultimately slows the OAT reaction at this metal cation. The measured rate differences between the open-shell Dy3+ and closed-shell Y3+ complexes demonstrate that using established principles of 4f ion sensitization may deliver new, selective modalities for differentiating the RE elements that do not depend on cation size.

Is the Measure Good Enough? Measurement Invariance and Validity of the Clance Imposter Phenomenon Scale in a University Population.

Imposter Phenomenon (IP) was coined in 1978 by Clance and Imes and has been an important construct in explaining individuals' experiences of believing that achievements are a result of luck or misperceptions of others rather than personal competence. The Clance Imposter Phenomenon Scale (CIPS), developed in 1985, is a prominent operationalization of this construct. Although this scale has been widely used since its inception, its factor structure has been inconsistent across studies and no tests of measurement invariance are documented in the literature. Using a large university sample (n = 830), the current study was designed to: (a) examine the factor structure of the CIPS using cross validation, (b) examine measurement invariance across gender, and (c) examine differences in the CIPS factor by demographics. We found that a single factor structure for the CIPS was the best fitting model. We also found that the measure achieved invariance across gender after removing item 18 (and in the absence of items 1, 2, and 19, removed for poor fit). Finally, we found that being single, a woman, and having experienced lower socioeconomic status (SES) were all associated with higher IP. We discuss these findings in the context of a university setting and suggest avenues for future research.

Addressing Adolescent Stress in School: Perceptions of a High School Wellness Center.

Adolescents are often burdened with academic, home, and peer stressors. With adolescent mental health issues and suicide on the rise, administrators have worked with nonprofit organizations and the community to address stress and internalized behavior problems. School-based wellness centers are tranquil rooms with various sensory activities, calming nature scenes, and sounds for relaxation purposes. School-based wellness centers may have behavioral effects by reducing exposure to aversive events and increasing access to positive and negative reinforcers. There has not yet been a formal study of school-based wellness centers published in the literature. In the present study, we used questionnaires to examine the perceptions of 752 students, 124 parents, and 69 school staff of their high school wellness center. Results indicated that stakeholders had positive perceptions of the wellness center. In particular, results implied that stakeholders believed the wellness center contributed to students' academic success, elevation of mood, confidence, and coping skills. Results also suggested that attendance at the wellness center was associated with a decrease in student stress and anxiety, though recommendations for improvements were noted. Implications and limitations of this study are discussed. Supplementary Information: The online version contains supplementary material available at 10.1007/s43494-022-00079-1.

Why do faculty resist change?

This article was migrated. The article was marked as recommended. Background: Much of what an educator needs to know to be successful is invisible to lay observers, leading to the assumption that teaching requires little formal study. Aims: This study is based on an 8- month faculty development workshop on student-centered teaching. Faculty members who made no noticeable changes in their teaching practices were compared to faculty who made noticeable and significant changes. Method: Using a qualitative narrative approach based on a structured interview we aimed to categorize the features of changers and resisters. Results: Faculty resisters did not see any need for changes in the way we teach, did not believe student-centered teaching to be more effective, could not appropriately define student-centered teaching, were motivated by extrinsic factors, and felt unvalued. Conversely, faculty changers were excited for changes and saw the need for change and for student-centered teaching, were intrinsically motivated, and felt valued as faculty members. Conclusion: We hypothesize that a main reason for resistance is the status quo bias. Implications for faculty development are discussed.

Test-Enhanced Learning and Incentives in Biology Education.

Cognitive scientists have recommended the use of test-enhanced learning in science classrooms. Test-enhanced learning includes the testing effect, in which learners' recall of information encountered in testing exceeds that of information not tested. The influence of incentives (e.g., points received) on learners who experience the testing effect in classrooms is less understood. The objective of our study was to examine the effects of incentives in a postsecondary biology course. We administered exams in the course using a quasi-experimental design with low and high point incentives and measured student learning. Although exposure to exams predicted better learning, incentive level did not moderate this effect, an outcome that contradicted recent laboratory findings that higher incentives decreased student recall. We discuss possible explanations of the disparate outcomes as well as the implications for further research on the testing effect in postsecondary biology classrooms.

Message-passing neural networks for high-throughput polymer screening.

Machine learning methods have shown promise in predicting molecular properties, and given sufficient training data, machine learning approaches can enable rapid high-throughput virtual screening of large libraries of compounds. Graph-based neural network architectures have emerged in recent years as the most successful approach for predictions based on molecular structure and have consistently achieved the best performance on benchmark quantum chemical datasets. However, these models have typically required optimized 3D structural information for the molecule to achieve the highest accuracy. These 3D geometries are costly to compute for high levels of theory, limiting the applicability and practicality of machine learning methods in high-throughput screening applications. In this study, we present a new database of candidate molecules for organic photovoltaic applications, comprising approximately 91 000 unique chemical structures. Compared to existing datasets, this dataset contains substantially larger molecules (up to 200 atoms) as well as extrapolated properties for long polymer chains. We show that message-passing neural networks trained with and without 3D structural information for these molecules achieve similar accuracy, comparable to state-of-the-art methods on existing benchmark datasets. These results therefore emphasize that for larger molecules with practical applications, near-optimal prediction results can be obtained without using optimized 3D geometry as an input. We further show that learned molecular representations can be leveraged to reduce the training data required to transfer predictions to a new density functional theory functional.

Exploring Diurnal Cortisol Rhythms of Kindergarten Teachers in Kosovo and Ukraine.

Teachers' stress is a dynamic combination of the individual teacher's characteristics and characteristics of the classroom and school environment. To date, there are limited studies on teachers' stress in the context of lower-middle-income countries (LMICs), where working conditions as well as general political and economic circumstances might pose a considerable threat for teachers' well-being. This study explores whether certain combinations of individual and environmental experiences of teachers in LMICs may result in stress, assessed as patterns of diurnal cortisol rhythm. Participants were kindergarten teachers in Kosovo and Ukraine, two LMICs in Europe. Latent Profile Analysis identified three subgroups of teachers that significantly differed on teachers' education and experience. Preliminary results of Latent Growth Modeling suggested differences between profiles in baseline waking cortisol and patterns of diurnal decline. Teachers in the profile that was characterized by the longest experience working in the field but the lowest level of education showed blunted cortisol in the morning and a flatter slope; a pattern that could indicate a maladaptive cortisol response. Future directions for studying stress processes among teachers in LMICs and implications for policy and practice on how to support teacher well-being in low-resource contexts are discussed.

Public comment sentiment on educational videos: Understanding the effects of presenter gender, video format, threading, and moderation on YouTube TED talk comments.

Scholars, educators, and students are increasingly encouraged to participate in online spaces. While the current literature highlights the potential positive outcomes of such participation, little research exists on the sentiment that these individuals may face online and on the factors that may lead some people to face different types of sentiment than others. To investigate these issues, we examined the strength of positive and negative sentiment expressed in response to TEDx and TED-Ed talks posted on YouTube (n = 655), the effect of several variables on comment and reply sentiment (n = 774,939), and the projected effects that sentiment-based moderation would have had on posted content. We found that most comments and replies were neutral in nature and some topics were more likely than others to elicit positive or negative sentiment. Videos of male presenters showed greater neutrality, while videos of female presenters saw significantly greater positive and negative polarity in replies. Animations neutralized both the negativity and positivity of replies at a very high rate. Gender and video format influenced the sentiment of replies and not just the initial comments that were directed toward the video. Finally, we found that using sentiment as a way to moderate offensive content would have a significant effect on non-offensive content. These findings have far-reaching implications for social media platforms and for those who encourage or prepare students and scholars to participate online.

Molecular dynamics and charge transport in organic semiconductors: a classical approach to modeling electron transfer.

Organic photovoltaics (OPVs) are a promising carbon-neutral energy conversion technology, with recent improvements pushing power conversion efficiencies over 10%. A major factor limiting OPV performance is inefficiency of charge transport in organic semiconducting materials (OSCs). Due to strong coupling with lattice degrees of freedom, the charges form polarons, localized quasi-particles comprised of charges dressed with phonons. These polarons can be conceptualized as pseudo-atoms with a greater effective mass than a bare charge. We propose that due to this increased mass, polarons can be modeled with Langevin molecular dynamics (LMD), a classical approach with a computational cost much lower than most quantum mechanical methods. Here we present LMD simulations of charge transfer between a pair of fullerene molecules, which commonly serve as electron acceptors in OSCs. We find transfer rates consistent with experimental measurements of charge mobility, suggesting that this method may provide quantitative predictions of efficiency when used to simulate materials on the device scale. Our approach also offers information that is not captured in the overall transfer rate or mobility: in the simulation data, we observe exactly when and why intermolecular transfer events occur. In addition, we demonstrate that these simulations can shed light on the properties of polarons in OSCs. Much remains to be learned about these quasi-particles, and there are no widely accepted methods for calculating properties such as effective mass and friction. Our model offers a promising approach to exploring mass and friction as well as providing insight into the details of polaron transport in OSCs.

Social and Psychological Factors Associated With Adolescent Physical Activity.

OBJECTIVE: The purpose of this study was to examine, using structural equation modeling, the associations between nominated friend physical activity (PA), friend social support with individual PA-related psychological factors, and adolescent PA. METHODS: Data were obtained from EAT 2010 (Eating and Activity Among Teens), a large cross-sectional study conducted in 20 middle and high schools. The sample consisted of 1951 adolescents (mean age: 14.25 ± 1.96, 54% female, 68% ethnic minorities). PA, parent and friend social support (perceived social support for PA from parents and friends), and psychological measures (PA enjoyment, PA self-efficacy, and PA barriers) were assessed by self-report questionnaires. The SEM analysis consisted of 1 observed variable: friend PA, and 2 latent constructs: psychological factors, perceived social support. RESULTS: The model was a good fit, indicating that there were significant direct effects of both friend PA (P < .01) and psychological factors (P < .0001) on adolescent PA. In addition, psychological factors mediated the association between friend PA and adolescent PA. CONCLUSION: The results of this model suggest that psychological factors and friend PA are associated with adolescent PA, and that psychological factors may play an important role. Future studies should further examine the association of both friend PA and psychological variables with adolescent PA.

Developmental trajectories of aggression, prosocial behavior, and social-cognitive problem solving in emerging adolescents with clinically elevated attention-deficit/hyperactivity disorder symptoms.

Middle school is a critical yet understudied period of social behavioral risks and opportunities that may be particularly difficult for emerging adolescents with attention-deficit/hyperactivity disorder (ADHD) given their childhood social difficulties. Relatively few ADHD studies have examined social behavior and social-cognitive problem solving beyond the elementary years, or examined aspects of positive (prosocial) behavior. The current study examined how middle school students with clinically elevated ADHD symptoms differ from their non-ADHD peers on baseline (6th grade) and age-related changes in prosocial and aggressive behavior, and the extent to which social-cognitive problem solving strategies mediate these relations. Emerging adolescents with (n = 178) and without (n = 3,806) clinically elevated, teacher-reported ADHD-combined symptoms were compared longitudinally across 6th through 8th grades using parallel process latent growth curve modeling, accounting for student demographic characteristics, oppositional-defiant disorder (ODD) symptoms, deviant peer association, school climate, and parental monitoring. Sixth graders with elevated ADHD symptoms engaged in somewhat fewer prosocial behaviors (d = -0.44) and more aggressive behavior (d = 0.20) relative to their peers. These small social behavioral deficits decreased but were not normalized across the middle school years. Contrary to hypotheses, social-cognitive problem solving was not impaired in the ADHD group after accounting for co-occurring ODD symptoms and did not mediate the association between ADHD and social behavior during the middle school years. ADHD and social-cognitive problem solving contributed independently to social behavior, both in 6th grade and across the middle school years; the influence of social-cognitive problem solving on social behavior was highly similar for the ADHD and non-ADHD groups.

Bidirectional associations between perceived parental support for violent and nonviolent responses and early adolescent aggressive and effective nonviolent behaviors.

The current study examined bidirectional relations between early adolescents' perceptions of parental support for violent and nonviolent responses to conflict and their aggressive and effective nonviolent behaviors six months later. Data was collected across the sixth and seventh grades for 520 adolescents at three middle schools in the southeastern United States. At baseline, participants were ages 10-14 (M = 11.29). Longitudinal path models showed that perceived parental support for violent responses was negatively associated with effective nonviolent behaviors and positively associated with aggressive behaviors across sixth and seventh grades. Across seventh grade, reciprocal negative relations were found between perceived parental support of nonviolent responses and aggressive behaviors. Effective nonviolent behaviors were positively associated with perceived parental support for nonviolent responses. Study implications include the importance of adolescent perceptions of parental support of violent and nonviolent responses in influencing early adolescents' effective nonviolent and aggressive behavior.

Close Packing of Nitroxide Radicals in Stable Organic Radical Polymeric Materials.

The relationship between the polymer network and electronic transport properties for stable radical polymeric materials has come under investigation owing to their potential application in electronic devices. For the radical polymer poly(2,2,6,6-tetramethylpiperidine-4-yl-1-oxyl methacrylate), it is unclear whether the radical packing is optimal for charge transport partially because the relationship between radical packing and molecular structure is not well-understood. Using the paramagnetic nitroxide radical as a probe of the polymer and synthetic techniques to control the radical concentration on the methyl methacrylate backbone, we investigate the dependence of radical concentration on molecular structure. The electron paramagnetic resonance data indicate that radicals in the PTMA assume a closest approach distance to each other when more than 60% of the backbone is populated with radical pendant groups. Below 60% coverage, the polymer rearranges to accommodate larger radical-radical spacing. These findings are consistent with theoretical calculations and help explain some experimentally determined electron-transport properties.

Reading and spelling skills in German third graders: Examining the role of student and context characteristics.

BACKGROUND: Educational processes and outcomes are influenced by a multitude of factors, including individual and contextual characteristics. Recently, studies have demonstrated that student and context characteristics may produce unique and cumulative effects on educational outcomes. AIMS: The study aimed to investigate (1) the relative contribution of student, classroom, and school characteristics to reading fluency and orthographic spelling, (2) the relative contribution of specific predictors to reading fluency and orthographic spelling within the sets of student, classroom, and school characteristics, and (3) whether the contribution of student, classroom, and school characteristics differs for reading fluency and orthographic spelling. SAMPLE: Participants were 789 German third-grade students from 56 classrooms in 34 schools. METHOD: Students completed an intelligence test and a questionnaire assessing self-control. Reading fluency and orthographic spelling performance were assessed using standardized achievement tests. Multilevel structural equation modelling was used to control for the hierarchical structure of educational data. RESULTS AND CONCLUSION: Variances in students' reading and spelling skills were in large part explained by student characteristics (>90%). Classroom and school characteristics yielded little variance. Student-level intelligence and self-control were significantly related to reading fluency. For orthographic spelling, student-level intelligence and self-control, class-average intelligence, and, at the school level, the socio-economic status of the school's neighbourhood were significant predictors. Future research needs to investigate relevant classroom and school factors that may directly and indirectly relate to academic outcomes.

Engagement in Training as a Mechanism to Understanding Fidelity of Implementation of the Responsive Classroom Approach.

Fidelity of implementation of classroom interventions varies greatly, a reality that is concerning because higher fidelity of implementation relates to greater effectiveness of the intervention. We analyzed 126 fourth and fifth grade teachers from the treatment group of a randomized controlled trial of the Responsive Classroom® (RC) approach. Prior to training in the intervention, we assessed factors that had the potential to represent a teacher's readiness to implement with fidelity. These included teachers' observed emotional support, teacher-rated use of intervention practices, teacher-rated self-efficacy, teacher-rated collective responsibility, education level, and years of experience, and they were not directly related to observed fidelity of implementation 2 years later. Further analyses indicated, however, that RC trainers' ratings of teachers' engagement in the initial weeklong RC training mediated the relation between initial observed emotional support and later observed fidelity of implementation. We discuss these findings as a way to advance understanding of teachers' readiness to implement new interventions with fidelity.

Quenching of the perylene fluorophore by stable nitroxide radical-containing macromolecules.

Stable nitroxide radical bearing organic polymer materials are attracting much attention for their application as next generation energy storage materials. A greater understanding of the inherent charge transfer mechanisms in such systems will ultimately be paramount to further advancements in the understanding of both intrafilm and interfacial ion- and electron-transfer reactions. This work is focused on advancing the fundamental understanding of these dynamic charge transfer properties by exploiting the fact that these species are efficient fluorescence quenchers. We systematically incorporated fluorescent perylene dyes into solutions containing the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) radical and controlled their interaction by binding the TEMPO moiety into macromolecules with varying morphologies (e.g., chain length, density of radical pendant groups). In the case of the model compound, 4-oxo-TEMPO, quenching of the perylene excited state was found to be dominated by a dynamic (collisional) process, with a contribution from an apparent static process that is described by an ∼2 nm quenching sphere of action. When we incorporated the TEMPO unit into a macromolecule, the quenching behavior was altered significantly. The results can be described by using two models: (A) a collisional quenching process that becomes less efficient, presumably due to a reduction in the diffusion constant of the quenching entity, with a quenching sphere of action similar to 4-oxo-TEMPO or (B) a collisional quenching process that becomes more efficient as the radius of interaction grows larger with increasing oligomer length. This is the first study that definitively illustrates that fluorophore quenching by a polymer system cannot be explained using merely a classical Stern-Volmer approach but rather necessitates a more complex model.

The influence of fidelity of implementation on teacher-student interaction quality in the context of a randomized controlled trial of the Responsive Classroom approach.

This study examined the direct and indirect effects between training in the Responsive Classroom® (RC) approach, teachers' uptake of RC practices, and teacher-student interaction quality, using a structural equation modeling framework. A total of 24 schools were randomly assigned to experimental or control conditions. Third- and fourth-grade teachers in treatment schools (n=132) received training in the RC approach, whereas teachers in control schools (n=107) continued "business as usual." Observers rated teachers' fidelity of implementation (FOI) of RC practices 5 times throughout the year using the Classroom Practices Observation Measure. In addition, teachers completed self-report measures of FOI, the Classroom Practices Teacher Survey and Classroom Practices Frequency Survey, at the end of the school year. Teacher-student interactions were rated during classroom observations using the Classroom Assessment Scoring System. Controlling for teachers' grade level and teacher-student interaction quality at pretest, RC training was expected to predict posttest teacher-student interaction quality directly and indirectly through FOI. Results supported only a significant indirect effect, ß=0.85, p=.002. Specifically, RC teachers had higher levels of FOI of RC practices, ß=1.62, p<.001, R2=.69. In turn, FOI related to greater improvement in teacher-student interaction quality, ß=0.52, p=.001, R2=.32. Discussion highlights factors contributing to variability in FOI and school administrators roles in supporting FOI.

Resonance Raman and temperature-dependent electronic absorption spectra of cavity and noncavity models of the hydrated electron.

Most of what is known about the structure of the hydrated electron comes from mixed quantum/classical simulations, which depend on the pseudopotential that couples the quantum electron to the classical water molecules. These potentials usually are highly repulsive, producing cavity-bound hydrated electrons that break the local water H-bonding structure. However, we recently developed a more attractive potential, which produces a hydrated electron that encompasses a region of enhanced water density. Both our noncavity and the various cavity models predict similar experimental observables. In this paper, we work to distinguish between these models by studying both the temperature dependence of the optical absorption spectrum, which provides insight into the balance of the attractive and repulsive terms in the potential, and the resonance Raman spectrum, which provides a direct measure of the local H-bonding environment near the electron. We find that only our noncavity model can capture the experimental red shift of the hydrated electron's absorption spectrum with increasing temperature at constant density. Cavity models of the hydrated electron predict a solvation structure similar to that of the larger aqueous halides, leading to a Raman O-H stretching band that is blue-shifted and narrower than that of bulk water. In contrast, experiments show the hydrated electron has a broader and red-shifted O-H stretching band compared with bulk water, a feature recovered by our noncavity model. We conclude that although our noncavity model does not provide perfect quantitative agreement with experiment, the hydrated electron must have a significant degree of noncavity character.