Search

The study of the redox chemistry of mid-actinides (U – Pu) has historically relied on cerium as a model, due to the accessibility of trivalent and tetravalent oxidation states for these ions. Recently, dramatic shifts of lanthanide 4+/3+ non-aqueous redox couples have been established within a homoleptic imidophosphorane ligand framework. Herein we extend the chemistry of the imidophosphorane ligand (NPC = [N=PtBu(pyrr)2]−; pyrr = pyrrolidinyl) to tetrahomoleptic NPC complexes of neptunium and cerium (1-M, 2-M, M = Np, Ce) and present comparative structural, electrochemical, and theoretical studies of these complexes. Large cathodic shifts in the M4+/3+ (M = Ce, U, Np) couples underpin the stabilization of higher metal oxidation states owing to the strongly donating nature of the NPC ligands, providing access to the U5+/4+, U6+/5+, and to an unprecedented, well-behaved Np5+/4+ redox couple. The differences in the chemical redox properties of the U vs. Ce and Np complexes are rationalized based on their redox potentials, degree of structural rearrangement upon reduction/oxidation, relative molecular orbital energies, and orbital composition analyses employing density functional theory.

BACKGROUND A challenge facing researchers when conducting mobile health (mHealth) research is the resources required to develop mobile apps. This can be a barrier to generating relevant knowledge in a timely manner. The recent rise of “no-code” software development platforms may overcome this challenge and enable researchers to decrease the cost and time required to develop mHealth research apps. OBJECTIVE To describe the development process and the lessons learned to build the no-code mHealth app design platform (Pathverse). METHODS The study took place between November 2019 to December 2021. In phase 1, we used a participatory research frame to gather key platform feature requirements. In phase 2, we used an agile software framework to develop the platform. In phase 3, we gathered user feedback through usability and acceptability testing. In phase 4, we further developed the platforms based on user feedback. RESULTS Our team consulted end-users (i.e. researchers) and utilized behaviour change technique (BCT) taxonomy and behaviour change models (i.e. multi-process action control framework) to guide the features developed. The first version of the Pathverse platform included features that allowed researchers to 1) design customized multimedia app content (e.g., interactive lessons), 2) set content delivery logic (e.g. only show new lessons when completing the previous lesson), 3) implement customized participant surveys, 4) provide self-monitoring tools 5) set personalized goals 6) customize app notification. Usability and acceptability testing revealed that researchers found the platform easy to navigate, and the features were initiative to use. Potential improvements included the ability to deliver adaptive interventions and add features such as community group chat. CONCLUSIONS To our knowledge, Pathverse is the first no-code mHealth app design platform for developing behaviour mHealth interventions. We successfully used behaviour change models and the BCT taxonomy to inform the feature requirements of Pathverse. Overall, the use of a participatory framework, combined with the agile and hybrid-agile software development process, enabled our team to successfully develop the Pathverse platform.

Theories in the social cognitive tradition have shown that many forms of regular physical activity (PA) are goal-directed; yet, the gap between intention and behavior is considerable, and these theories generally have limited explanation for intention-behavior discordance. Multi-process action control (M-PAC) was created as an organizing schematic to describe key constructs proposed to bridge the intention-behavior relationship across the initial adoption to ongoing sustainability of PA. In this chapter, we overview the theoretical lens behind M-PAC, suggesting that intention-behavior discordance is likely occurring from both strategic challenges in goal pursuit and automatic tendencies that determine why some people fail to follow through with PA intentions regularly. The proposed pathways for how critical reflective (affective judgments), regulatory (e.g. plans, monitoring, building a supportive social and physical environment), and eventual reflexive (habit, identity) constructs in M-PAC impact action control are highlighted. Finally, the efficacy of the M-PAC framework is reviewed with evidence collected thus far. Results from the observational studies generally support the proposed reflective, regulatory, and reflexive constructs of M-PAC as independent predictors of intention-behavior relations. Experimental application of M-PAC is preliminary but early evidence is also generally supportive that modifications to M-PAC constructs collectively and independently change PA. Overall, contemporary research on M-PAC demonstrates that its constructs may act as a bridge of the intention-behavior gap and, thus, augment traditional social cognitive approaches but sustained, higher quality research is warranted.

Purpose Physical activity promotion has mostly focused on theories of intention-formation, with the assumption that positive intentions will lead to behaviour. Though necessary, exercise intentions alone are often not sufficient to improve physical activity behaviour. The Multi-Process Action Control (M-PAC) framework builds on previous intention-based theories by including both determinants of intention formation and its translation into behaviour. The purpose of this study was to describe the process of developing a self-guided web-based intervention to promote physical activity among adults using the M-PAC model. Procedures The development process consisted of the following three phases: 1) Intervention planning: determine intervention needs and requirements; 2) Intervention development: use an iterative process to design a web-based physical activity intervention based on the M-PAC framework; 3) Pilot testing: conduct usability and acceptability assessment on the web-based intervention to further enhance user experience. Principal results The intervention planning phase suggested that there is a need for web-based physical activity interventions and there is currently no web-based intervention designed using the M-PAC model. In phase two, we adopted an iterative process to develop a 10-week self-guided web-based intervention to help adults (>18 years of age) to meet 150 min of moderate to vigorous physical activity per week. The pilot testing phase yielded valuable feedback on usability, content, and design of the web-based intervention. Major conclusions The development of a web-based physical activity intervention using the M-PAC model could further enhance the effectiveness of web-based interventions and have a significant impact on extending the reach of existing physical activity promotion programs. This study has reinforced the importance of an iterative development process that involves a multi-disciplinary team to design a web-based intervention to promote physical activity. The process enabled the team to clarify the needs for an intervention for our target users, and provided valuable feedback on the design and content of the web-based intervention. Future studies are now needed to evaluate the effectiveness of our web-based intervention., Highlights • This study described the development of a self-guided web-based program to promote physical activity among adults. • This is the first web-based physical activity program designed using the Multi-Process Action Control framework. • The web-based program was refined after usability and acceptability assessments. • Reinforced the importance of an iterative development process that involves a multi-disciplinary team and end users.

Background A challenge facing researchers conducting mobile health (mHealth) research is the amount of resources required to develop mobile apps. This can be a barrier to generating relevant knowledge in a timely manner. The recent rise of “no-code” software development platforms may overcome this challenge and enable researchers to decrease the cost and time required to develop mHealth research apps. Objective We aimed to describe the development process and the lessons learned to build Pathverse, a no-code mHealth app design platform. Methods The study took place between November 2019 and December 2021. We used a participatory research framework to develop the mHealth app design platform. In phase 1, we worked with researchers to gather key platform feature requirements and conducted an exploratory literature search to determine needs related to this platform. In phase 2, we used an agile software framework (Scrum) to develop the platform. Each development sprint cycle was 4 weeks in length. We created a minimum viable product at the end of 7 sprint cycles. In phase 3, we used a convenience sample of adults (n=5) to gather user feedback through usability and acceptability testing. In phase 4, we further developed the platform based on user feedback, following the V-model software development process. Results Our team consulted end users (ie, researchers) and utilized behavior change technique taxonomy and behavior change models (ie, the multi-process action control framework) to guide the development of features. The first version of the Pathverse platform included features that allowed researchers to (1) design customized multimedia app content (eg, interactive lessons), (2) set content delivery logic (eg, only show new lessons when completing the previous lesson), (3) implement customized participant surveys, (4) provide self-monitoring tools, (5) set personalized goals, and (6) customize app notifications. Usability and acceptability testing revealed that researchers found the platform easy to navigate and that the features were intuitive to use. Potential improvements include the ability to deliver adaptive interventions and add features such as community group chat. Conclusions To our knowledge, Pathverse is the first no-code mHealth app design platform for developing mHealth interventions for behavior. We successfully used behavior change models and the behavior change technique taxonomy to inform the feature requirements of Pathverse. Overall, the use of a participatory framework, combined with the agile and hybrid-agile software development process, enabled our team to successfully develop the Pathverse platform.

Synthetic strategies to yield molecular complexes of high-valent lanthanides, other than the ubiquitous Ce4+ ion, are exceptionally rare, and thorough, detailed characterization in these systems is limited by complex lifetime and reaction and isolation conditions. The synthesis of high-symmetry complexes in high purity with significant lifetimes in solution and solid-state are essential for determining the role of ligand-field splitting, multiconfigurational behavior, and covalency in governing the reactivity and physical properties of these potentially technologically transformative tetravalent ions. We report the synthesis and physical characterization of an S4 symmetric, four-coordinate tetravalent terbium complex, [Tb(NP(1,2-bis-tBu-diamidoethane)(NEt2))4] (where Et is ethyl and tBu is tert-butyl). The ligand field in this complex is weak and the metal-ligand bonds sufficiently covalent so that the tetravalent terbium ion is stable and accessible via a mild oxidant from the anionic, trivalent, terbium precursor, [(Et2O)K][Tb(NP(1,2-bis-tBu-diamidoethane)(NEt2))4]. The significant stability of the tetravalent complex enables its thorough characterization. The step-wise development of the supporting ligand points to key ligand control elements for further extending the known tetravalent lanthanide ions in molecular complexes. Magnetic susceptibility, electron paramagnetic resonance (EPR) spectroscopy, X-ray absorption near-edge spectroscopy (XAS), and density functional theory studies indicate a 4f7 ground state for [Tb(NP(1,2-bis-tBu-diamidoethane)(NEt2))4] with considerable zero-field splitting: demonstrating that magnetic, tetravalent lanthanide ions engage in covalent metal-ligand bonds. This result has significant implications for the use of tetravalent lanthanide ions in magnetic applications since the observed zero-field splitting is intermediate between that observed for the trivalent lanthanides and for the transition metals. The similarity of the multiconfigurational behavior in the ground state of [Tb(NP(1,2-bis-tBu-diamidoethane)(NEt2))4] (measured by Tb L3-edge XAS) to that observed in TbO2 implicates ligand control of multiconfigurational behavior as a key component of the stability of the complex.

Rare-earth dihydride LnH x ( x ≅ 2) formation was observed by the exposure of rare-earth -metal thin films to water vapour at fairly low temperatures. In the case of neodymium, this is accompanied by the slow formation of the hydroxide but, in the case of dysprosium, the hydride alone is obtained at about 413 K. There are no hydrated contaminants and the dysprosium thin films do not oxidize until a higher temperature (about 473 K) is reached.

Thin films of rare-earth metals always getter hydrogen very easily under ordinary conditions of preparation. It is shown from X-ray and electron diffraction experiments that the f.c.c. hydrides appear as single-crystal inclusions especially in the case of the yttric series (except for ytterbium). The hydride inclusions yield conspicuous f.c.c. diffraction patterns which should not be mistaken for a rare-earth monoxide, LnO, or for an f.c.c. phase of the metal. Oxidation of the “metallic” thin films yields sesquioxide thin films. The electron diffraction pattern of C-type sesquioxides for large crystals in thin films exhibits “forbidden” diffraction spots which apparently do not agree with the recognized T7h space group. It is shown that these forbidden spots appear because of multiple diffraction effects.

La variete C des sesquioxydes de terres rares est etudiee par microscopie et diffraction electroniques. Les diagrammes sont caracterises par des anneaux et des taches de diffraction (110, 330 etc.…), supplementaires par rapport a la diffraction des rayons X, quiparaissent incompatibles avec le groupe d'espace classique Th7 de C-Ln2O3. Les repartitions possibles des lacunes dans la structure fluorine LnO2 conduisant a la stoechiometrie Ln2O3 sont discutees. On montre cependant que les taches supplementaires observees n'appartiennent pas au reseau reciproque. The C-type of rare earth sesquioxides is studied by electron microscopy and diffraction. The patterns are characterized by supplementary diffraction rings and spots (110, 330,…) with respect to X-ray diffraction, which seem to be incompatible with the admitted Th7 space group of C-Ln2O3. The possible vacancy arrays in the fluorite structure LnO2 yielding the Ln2O3 stoichiometry are discussed. It is shown, however, that the additional forbidden spots do not belong to the reciprocal lattice.

In thin films of A-type praseodymium sesquioxide (hexagonal), B-phase (monoclinic) domains can be produced. The B to A-transformation has a martensitic character.