Zinc calixarene complexes for the ring opening polymerization of cyclic esters

Reaction of Zn(C₆F₅)₂·toluene (two equivalents) with 1,3-dipropoxy-p-tert-butyl-calix[4]arene (L¹H₂) led to the isolation of the complex [{Zn(C₆F₅)}₂L¹] (1), whilst similar use of Zn(Me)₂ resulted in the known complex [{Zn(Me)}₂L¹] (2). Treatment of L¹H₂ with in situ prepared Zn{N(SiMe₃)₂}₂ in refluxing toluene led to the isolation of the compound [(Na)ZnN(SiMe₃)₂L¹] (3). The stepwise reaction of L¹H₂ and sodium hydride, followed by ZnCl₂ and finally NaN(SiMe₃)₂ yielded the compound [Zn{N(SiMe₃)₂}₂L¹] (4). The reaction between three equivalents of Zn(C₆F₅)₂·toluene and oxacalix[3]arene (L²H₃) at room temperature formed the compound {[Zn(C₆F₅)]₃L²} (5); heating of 5 in acetonitrile caused the ring opening of the parent oxacalix[3]arene and rearrangement to afford the complex [(L²)Zn₆(C₆F₅)(R)(RH)OH]·5MeCN R = C₆F₅CH₂-(p-ᵗBuPhenolate-CH₂OCH₂–)₂–p-ᵗBuPhenolate-CH₂O⁻)³⁻ (6). The molecular structures of the new complexes 1, 3 and 6, together with that of the known complex 2, whose solid state structure has not previously been reported, have been determined. Compounds 1, 3–5 have been screened for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and rac-lactide. Compounds featuring a Zn–C₆F₅ fragment were found to be poor ROP pre-catalysts as they did not react with benzyl alcohol to form an alkoxide. By contrast, compound 4, which contains a zinc silylamide linkage, was the most active of the zinc-based calix[4]arene compounds screened and was capable of ROP at ambient temperature with 65% conversion over 4 h

Augmented reality and worked examples: Targeting organic chemistry competence

Instructional guidance, provided using worked examples, helps the inexperienced learner cope with complex information, that may be difficult to process in limited capacity working memory. For students of chemistry, such complex information can pertain to the visualisation of structural changes in molecules throughout chemical reactions. This can be alleviated through the affordances of augmented reality (AR) technology. 3D structures are important as they have a crucial impact on the chemical and physical properties of molecules. Within a framework of Cognitive Load Theory, this study illustrates how AR-supported worked examples may enhance learning of electrophilic aromatic substitution. The participant cohort were FHEQ level 5 undergraduate students studying a module of organic chemistry. In addition, the achievement motivation of learner's was also explored, and how this may be impacted by the provision of AR technology and worked examples. The control group was provided with a copy of our worked examples that contained 2D reaction mechanism drawings. Data was collected using a combination of quantitative instruments and qualitative surveys/interviews. For this cohort of students, significant intragroup improvements, and greater normalised change values, in conceptual understanding were observed in the AR group. This was not observed in the control group. No significant intergroup differences in reported cognitive load or achievement motivation of students were found. This was unaffected when introducing prior relevant chemistry experience as a covariate. Student feedback and subsequent thematic analysis show not only the positive impacts on student engagement, but also how students convey their understanding of electrophilic aromatic substitution principles

Fostering Motivation toward Chemistry through Augmented Reality Educational Escape Activities. A Self-Determination Theory Approach

There is little doubt that motivation influences the extent to which individuals engage with online learning experiences. With the increasing role of digital technologies within chemistry higher education, this study illustrates how an augmented reality (AR)-supported educational escape activity (EEA), based on topics of inorganic stereochemistry, can be employed within an online environment. The design aspects of our activity were guided by principles of Self-Determination Theory (SDT)─an intrinsic-extrinsic theory of motivation. We sought to actively support the fundamental needs of competency, autonomy, and relatedness. Our control group was provided with a copy of our EEA that utilized two-dimensional drawings. Reported measures of competency were seen as a positive predictor of intrinsic motivation. However, in this study, this was not observed to be a positive predictor of academic performance. The introduction of AR, over and above the EEA, did not result in any significant differences in reported intrinsic motivation or post-test scores on our stereochemistry test instrument. Collected qualitative data suggest that participants found the activity to be useful and engaging. Through students’ discussions, we have provided evidence of how design aspects of the EEA support the psychological needs satisfaction outlined by SDT. The design of our EEA provides one approach to implementing this style of learning activity, in a way that supports virtual presence and is scalable to large student cohorts

HRM Practices Affecting Extrinsic and Intrinsic Motivation of Knowledge Receivers and their Effect on Intra-MNC Knowledge Transfer.

This paper explores why and how HRM matters for knowledge transfer within multinational corporations. It is built upon the premise that there are certain HRM practices influencing extrinsic and intrinsic motivation of knowledge receivers. It is found that complementarity among HRM practices exists but does not always have a positive effect on knowledge transfer. Three hypotheses derived from these arguments are tested on data from 92 subsidiaries of Danish multinational corporations located in 11 countries

Ancient geological dynamics impact neutral biodiversity accumulation and are detectable in phylogenetic reconstructions

ACKNOWLEDGMENTS This work was supported by grants from the Ministry of Research and Technology, Indonesia to Berry Juliandi (No. 2488/IT3.L1/PN/2020 and No. 3982/IT3.L1/PN/2020) and funding from NERC/NEWTON sto Adam C. Algar, Greta Bocedi, Cecile Gubry-Rangin, Lesley Lancaster, Alexander S. T. Papadopulos and Justin M. J. Travis.Peer reviewedPublisher PD

The BrainMap strategy for standardization, sharing, and meta-analysis of neuroimaging data

<p>Abstract</p> <p>Background</p> <p>Neuroimaging researchers have developed rigorous community data and metadata standards that encourage meta-analysis as a method for establishing robust and meaningful convergence of knowledge of human brain structure and function. Capitalizing on these standards, the BrainMap project offers databases, software applications, and other associated tools for supporting and promoting quantitative coordinate-based meta-analysis of the structural and functional neuroimaging literature.</p> <p>Findings</p> <p>In this report, we describe recent technical updates to the project and provide an educational description for performing meta-analyses in the BrainMap environment.</p> <p>Conclusions</p> <p>The BrainMap project will continue to evolve in response to the meta-analytic needs of biomedical researchers in the structural and functional neuroimaging communities. Future work on the BrainMap project regarding software and hardware advances are also discussed.</p

Solubility and Permeation of Hydrogen Sulfide in Lipid Membranes

Hydrogen sulfide (H2S) is mainly known for its toxicity but has recently been shown to be produced endogenously in mammalian tissues and to be associated with physiological regulatory functions. To better understand the role of biomembranes in modulating its biological distribution and effects; we measured the partition coefficient of H2S in models of biological membranes. The partition coefficients were found to be 2.1±0.2, 1.9±0.5 and 2.0±0.6 in n-octanol, hexane and dilauroylphosphatidylcholine liposome membranes relative to water, respectively (25°C). This two-fold higher concentration of H2S in the membrane translates into a rapid membrane permeability, Pm = 3 cm s−1. We used a mathematical model in three dimensions to gain insight into the diffusion of total sulfide in tissues. This model shows that the sphere of action of sulfide produced by a single cell expands to involve more than 200 neighboring cells, and that the resistance imposed by lipid membranes has a significant effect on the diffusional spread of sulfide at pH 7.4, increasing local concentrations. These results support the role of hydrogen sulfide as a paracrine signaling molecule and reveal advantageous pharmacokinetic properties for its therapeutic applications

Improving quality of life through the routine use of the patient concerns inventory for head and neck cancer patients: main results of a cluster preference randomised controlled trial

Funding: UK National Institute for Health Research (NIHR) under its Research for Patient Benefit (RfPB) Programme (Grant Reference Number PB-PG-0215-36047).Purpose The patient concerns inventory (PCI) is a prompt list allowing head and neck cancer (HNC) patients to discuss issues that otherwise might be overlooked. This trial evaluated the effectiveness of using the PCI at routine outpatient clinics for one year after treatment on health-related QOL (HRQOL). Methods   A pragmatic cluster preference randomised control trial with 15 consultants, 8 ‘using’ and 7 ‘not using’ the PCI intervention. Patients treated with curative intent (all sites, disease stages, treatments) were eligible. Results   Consultants saw a median (inter-quartile range) 16 (13–26) patients, with 140 PCI and 148 control patients. Of the pre-specified outcomes, the 12-month results for the mean University of Washington Quality of Life (UW-QOLv4) social-emotional subscale score suggested a small clinical effect of intervention of 4.6 units (95% CI 0.2, 9.0), p = 0.04 after full adjustment for pre-stated case-mix. Results for UW-QOLv4 overall quality of life being less than good at 12 months (primary outcome) also favoured the PCI with a risk ratio of 0.83 (95% CI 0.66, 1.06) and absolute risk 4.8% (− 2.9%, 12.9%) but without achieving statistical significance. Other non-a-priori analyses, including all 12 UWQOL domains and at consultant level also suggested better HRQOL with PCI. Consultation times were unaffected and the number of items selected decreased over time. Conclusion   This novel trial supports the integration of the PCI approach into routine consultations as a simple low-cost means of benefiting HNC patients. It adds to a growing body of evidence supporting the use of patient prompt lists more generally.Publisher PDFPeer reviewe