Exploring the excited state character of nitroarylcarbazole derivatives using wavefunction analysis

The solid state fluorescence behaviour of a family of 9-(4-Nitroaryl)carbazoles is investigated via calculations of their electronically excited states. Ground state optimisations show that for many of the molecules, the most stable conformation has the nitroaryl moiety twisted relative to the carbazole. Vertical excitation calculations and subsequent wavefunction analysis [1] show that for molecules which are solid state emissive, the lowest lying singlet state has a major contribution from a charge transfer state from the carbazole donor to the nitroaryl acceptor. For molecules which are non-emissive, the lowest lying singlet state is found to be an n – π* state. We find that the energy of the charge transfer state decreases as the electron withdrawing power of the nitroaryl acceptor is increased. Calculations of excitations for molecules with orthogonal conformations suggest that the charge transfer state is dark, as indicated by a very small oscillator strength. The question, then, is: how can these molecules be solid state emissive if the lowest lying excited state is dark? A scan of the torsion angle shows that the oscillator strength increases significantly as the molecule becomes more planar, and the energy profile for this rotation is relatively flat. We therefore propose that provided that stacking in the solid state leads to small perturbations in the molecular geometry and the lowest lying singlet is a charge transfer state, the molecule will be solid state emissive. [1] F. Plasser “Theodore 2.0.2: a package for theoretical density, orbital relaxation and exciton analysis”; available from http://theodore-qc.sourceforge.ne

Exploring the excited state character of nitroarylcarbazole derivatives using wavefunction analysis

The solid state fluorescence behaviour of a family of 9-(4-Nitroaryl)carbazoles is investigated via calculations of their electronically excited states. Ground state optimisations show that generally, the most stable conformation has the nitroaryl moiety twisted relative to the carbazole. Vertical excitation calculations and subsequent wavefunction analysis [1] show that for molecules which are solid state emissive, the lowest lying singlet state has a major contribution from a charge transfer state from the carbazole donor to the nitroaryl acceptor. For molecules which are non-emissive, the lowest lying singlet state is found to be an nπ* state on the nitro group. Moreover, we demonstrate how the assignment of these states can be done via a fully automated procedure. We find that the energy of the charge transfer state decreases as the electron withdrawing power of the nitroaryl acceptor is increased. Calculations of excitations for molecules with orthogonal conformations suggest that the charge transfer state is dark, as indicated by a very small oscillator strength. The question, then, is: how can these molecules be solid state emissive if the lowest lying excited state is dark? A scan of the torsion angle shows that the oscillator strength increases significantly as the molecule becomes more planar, and the energy profile for this rotation is relatively flat. We therefore propose that provided that stacking in the solid state leads to small perturbations in the molecular geometry and the lowest lying singlet is a charge transfer state, the molecule will be solid state emissive. References 1. F. Plasser “Theodore 2.0.2: a package for theoretical density, orbital relaxation and exciton analysis”; available from http://theodore-qc.sourceforge.ne

Reactive Video: Movement Sonification as Auditory Feedback for Supporting Physical Activity

This paper provides initial efforts in developing and evaluating a real-time movement sonification framework for physical activity practice and learning. Reactive Video provides an interactive, vision-based, adaptive video playback with auditory feedback on users' performance to better support when learning and practicing new physical skills. We implement the sonification for auditory feedback design by extending the Web Audio API framework. The current application focuses on Tai-Chi performance and provides two main audio cues to users for several Tai Chi exercises. We provide our design approach, implementation, and sound generation and mapping, specifically for interactive systems with direct video manipulation. Our observations reveal the relationship between the movement-to-sound mapping and characteristics of the physical activity

Reactive Video:Adaptive Video Playback Based on User Motion for Supporting Physical Activity

Videos are a convenient platform to begin, maintain, or improve a ftness program or physical activity. Traditional video systems allow users to manipulate videos through specifc user interface actions such as button clicks or mouse drags, but have no model of what the user is doing and are unable to adapt in useful ways. We present adaptive video playback, which seamlessly synchronises video playback with the user’s movements, building upon the principle of direct manipulation video navigation. We implement adaptive video playback in Reactive Video, a vision-based system which supports users learning or practising a physical skill. The use of pre-existing videos removes the need to create bespoke content or specially authored videos, and the system can provide real-time guidance and feedback to better support users when learning new movements. Adaptive video playback using a discrete Bayes and particle flter are evaluated on a data set collected of participants performing tai chi and radio exercises. Results show that both approaches can accurately adapt to the user’s movements, however reversing playback can be problematic

Elucidating the non-radiative losses encountered in intramolecular charge transfer compounds with benzodithiophene-4,8-dione acceptors

A new yellow-emitting quadrupolar donor-π-acceptor-π-donor (D-π-A-π-D) molecule compound has been synthesised featuring benzo-[1,2-c:4,5-c′]dithiophene-4,8-dione as the acceptor. This molecule was prepared for the purpose of elucidating the origins of the very low photoluminescence quantum yield encountered in its thermally activated delayed fluorescent (TADF) red-emitting isomer which used benzo-[1,2-b:4,5-b′]dithiophene-4,8-dione as the acceptor. The molecule was designed to circumvent the energy gap law, by having a wider HOMO-LUMO gap, while retaining a comparable singlet-triplet gap but ultimately demonstrates even weaker photoluminescence than the red isomer. It shows extremely fast intersystem crossing followed by rapid non-radiative decay and no observable TADF. The electronic structure of this new molecule has been studied using cyclic voltammatery alongside steady-state and transient optical spectroscopy, with observations underpinned by computational insights. To identify whether the observations made from the experimental results might be general properties of benzodithiophene-4,8-dione containing emitters, a computational study is extended to the four isomers of benzodithiophene-4,8-dione in comparison with 9,10-anthraquinone. The results suggest that the singlet and triplet manifolds of these systems are strongly coupled via spin-orbit interactions, and explain how the relative electron-accepting strength of these quinones arises from an interplay between the resonance gains or losses of the central benzene and fused thiophene rings upon photoexcitation. This provides valuable insights into the design principles required for efficient organic light-emitting materials.</p

In situ monitoring and mechanism of the mechanochemical formation of a microporous MOF-74 framework

Mechanochemistry provides a rapid, efficient route to metal-organic framework Zn-MOF-74 directly from a metal oxide and without bulk solvent. In situ synchrotron X-ray diffraction monitoring of the reaction course reveals two new phases and an unusual step-wise process in which a close-packed intermediate reacts to form the open framework. The reaction can be performed on a gram scale to yield a highly porous material after activation

Lipoprotein lipase is active as a monomer

Lipoprotein lipase (LPL), the enzyme that hydrolyzes triglycerides in plasma lipoproteins, is assumed to be active only as a homodimer. In support of this idea, several groups have reported that the size of LPL, as measured by density gradient ultracentrifugation, is ∼110 kDa, twice the size of LPL monomers (∼55 kDa). Of note, however, in those studies the LPL had been incubated with heparin, a polyanionic substance that binds and stabilizes LPL. Here we revisited the assumption that LPL is active only as a homodimer. When freshly secreted human LPL (or purified preparations of LPL) was subjected to density gradient ultracentrifugation (in the absence of heparin), LPL mass and activity peaks exhibited the size expected of monomers (near the 66-kDa albumin standard). GPIHBP1-bound LPL also exhibited the size expected for a monomer. In the presence of heparin, LPL size increased, overlapping with a 97.2-kDa standard. We also used density gradient ultracentrifugation to characterize the LPL within the high-salt and low-salt peaks from a heparin-Sepharose column. The catalytically active LPL within the high-salt peak exhibited the size of monomers, whereas most of the inactive LPL in the low-salt peak was at the bottom of the tube (in aggregates). Consistent with those findings, the LPL in the low-salt peak, but not that in the high-salt peak, was easily detectable with single mAb sandwich ELISAs, in which LPL is captured and detected with the same antibody. We conclude that catalytically active LPL can exist in a monomeric state

Primary irritant and delayed-contact hypersensitivity reactions to the freshwater cyanobacterium Cylindrospermopsis raciborskii and its associated toxin cylindrospermopsin

BACKGROUND: Freshwater cyanobacteria are common inhabitants of recreational waterbodies throughout the world; some cyanobacteria can dominate the phytoplankton and form blooms, many of which are toxic. Numerous reports in the literature describe pruritic skin rashes after recreational or occupational exposure to cyanobacteria, but there has been little research conducted on the cutaneous effects of cyanobacteria. Using the mouse ear swelling test (MEST), we sought to determine whether three toxin-producing cyanobacteria isolates and the purified cyanotoxin cylindrospermopsin produced delayed-contact hypersensitivity reactions. METHODS: Between 8 and 10 female Balb/c mice in each experiment had test material applied to depilated abdominal skin during the induction phase and 10 or 11 control mice had vehicle only applied to abdominal skin. For challenge (day 10) and rechallenge (day 17), test material was applied to a randomly-allocated test ear; vehicle was applied to the other ear as a control. Ear thickness in anaesthetised mice was measured with a micrometer gauge at 24 and 48 hours after challenge and rechallenge. Ear swelling greater than 20% in one or more test mice is considered a positive response. Histopathology examination of ear tissues was conducted by independent examiners. RESULTS: Purified cylindrospermopsin (2 of 9 test mice vs. 0 of 5 control mice; p = 0.51) and the cylindrospermopsin-producing cyanobacterium C. raciborskii (8 of 10 test mice vs. 0 of 10 control mice; p = 0.001) were both shown to produce hypersensitivity reactions. Irritant reactions were seen on abdominal skin at induction. Two other toxic cyanobacteria (Microcystis aeruginosa and Anabaena circinalis) did not generate any responses using this model. Histopathology examinations to determine positive and negative reactions in ear tissues showed excellent agreement beyond chance between both examiners (κ = 0.83). CONCLUSION: The irritant properties and cutaneous sensitising potential of cylindrospermopsin indicate that these toxicological endpoints should be considered by public health advisors and reservoir managers when setting guidelines for recreational exposure to cyanobacteria

The International Collaboration of Orthopaedic Nursing (ICON): Best practice nursing care standards for older adults with fragility hip fracture

© 2018 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 12 month embargo from date of publication (November 2018) in accordance with the publisher’s archiving policyThe purpose of this document is to provide nurses who care for older adults with fragility hip fracture with a framework to promote safe and optimal care for this vulnerable population. The successful application of the standards of care contained in this document requires clinical expertise and evidence-supported decision-making in order to maximize patient outcomes. In 2012, 2013 a two part consensus document published in the International Journal of Orthopaedic and Trauma Nursing entitled “Acute nursing care of the older adult with fragility hip fracture: an international perspective” was developed by nursing leaders from seven countries across 3 continents who delineated the recommended care standards for this group of patients (Maher et al., 2012; Maher et al., 2013)