Beyond Rubik: The Embodiment-Presence-Interactivity Cube applied to exercise.

Evidence-based interventions are needed to promote engagement in physical activity. Audio-visual stimuli are frequently employed to enhance the exercise experience. Nonetheless, there is a paucity of research that examines the qualities of technological devices that are employed. Using the Embodiment-Presence-Interactivity Cube (Flavián et al., 2019) as a guiding conceptual framework, the aim of this registered report was to examine how each dimension of the cube (i.e., embodiment, presence and interactivity) influenced a range of exercise-related affective and perceptual variables. A counterbalanced within-subjects design was employed (N = 24). Participants completed 20-min exercise bouts on a cycle ergometer under four conditions: Television, augmented reality, 360° video and virtual reality. A repeated-measures ANOVA indicated a significant Condition × Timepoint interaction for affective valence (p = 0.046), with greater embodiment offered by technological devices leading to more positive responses. Analyses also indicated main effects of condition for exercise enjoyment, remembered pleasure and forecasted pleasure, with greater presence of technological devices leading to more positive responses. Technologies that combine high levels of embodiment, presence and interactivity (e.g., virtual reality) appear to yield several benefits in terms of in-task (e.g., affective valence) and post-task (e.g., remembered pleasure) responses for exercise conducted at ventilatory threshold.

Nonadiabatic Molecular Dynamics of Water Cluster Dissociation by Vacuum Ultraviolet Absorption or Electron Impact Excitation.

After five decades of investigation since the 1970s, the nature of photon-induced or electron-induced water dissociation is still largely studied only in the gas phase, with a notable absence of dynamics studies of water clusters and bulk water. We study the problem with density functional theory and the nonadiabatic fewest switches surface hopping technique considering both singlet and triplet excited states to study the dissociation of water clusters leading mainly to OH + H. For clusters of 40 water molecules, the mean dissociation time was found to be <10 fs, and the threshold energy was ∼6 eV. Dissociation is almost exclusively associated with the cluster surface due to the lower energy of surface water excited states relative to the bulk. Recombination plays a major role in vacuum ultraviolet dissociation. O + H2 is found as a minor product in the dissociation and is mostly produced in "roaming" trajectories.

Trifluoromethylation of 2D Transition Metal Dichalcogenides: A Mild Functionalization and Tunable p-Type Doping Method.

Chemical modification is a powerful strategy for tuning the electronic properties of 2D semiconductors. Here we report the electrophilic trifluoromethylation of 2D WSe2 and MoS2 under mild conditions using the reagent trifluoromethyl thianthrenium triflate (TTT). Chemical characterization and density functional theory calculations reveal that the trifluoromethyl groups bind covalently to surface chalcogen atoms as well as oxygen substitution sites. Trifluoromethylation induces p-type doping in the underlying 2D material, enabling the modulation of charge transport and optical emission properties in WSe2. This work introduces a versatile and efficient method for tailoring the optical and electronic properties of 2D transition metal dichalcogenides.

Exciplex Emission and Förster Resonance Energy Transfer in Polycyclic Aromatic Hydrocarbon-Based Bischromophoric Cyclophanes and Homo[2]catenanes.

Energy transfer and exciplex emission are not only crucial photophysical processes in many living organisms but also important for the development of smart photonic materials. We report, herein, the rationally designed synthesis and characterization of two highly charged bischromophoric homo[2]catenanes and one cyclophane incorporating a combination of polycyclic aromatic hydrocarbons, i.e., anthracene, pyrene, and perylene, which are intrinsically capable of supporting energy transfer and exciplex formation. The possible coconformations of the homo[2]catenanes, on account of their dynamic behavior, have been probed by Density Functional Theory calculations. The unique photophysical properties of these exotic molecules have been explored by steady-state and time-resolved absorption and fluorescence spectroscopies. The tetracationic pyrene-perylene cyclophane system exhibits emission emanating from a highly efficient Förster resonance energy transfer (FRET) mechanism which occurs in 48 ps, while the octacationic homo[2]catenane displays a weak exciplex photoluminescence following extremely fast (<0.3 ps) exciplex formation. The in-depth fundamental understanding of these photophysical processes involved in the fluorescence of bischromophoric cyclophanes and homo[2]catenanes paves the way for their use in future bioapplications and photonic devices.

A systematic narrative review of extrinsic strategies to improve affective responses to exercise.

Background: Extrinsic strategies affect the exercise experience but fall outside the frequency, intensity, time, and type (i.e., dose-determining) principles. To our knowledge, no systematic review has focused on extrinsic strategies to influence the affective responses to exercise. The objective was to identify extrinsic strategies that seek to influence affective responses during exercise and other motivationally relevant variables including post-exercise momentary affective valence, remembered and forecasted pleasure, and enjoyment. Methods: For inclusion, eligible articles reported peer-reviewed original research, used acute bouts of exercise, and used a dimensional approach for measuring affective responses or measured enjoyment post-exercise. Web of Science, PubMed, and PsychINFO databases were last searched on 10th September 2021. Quality assessment was completed following the Effective Public Health Practice Project approach. Results were presented using a narrative synthesis. Results: 125 studies were included with sample descriptions, study design (extrinsic strategies, mode, type, intensity, and duration), measurement details, and results summarised for each study. Conclusions: 71% of studies were categorised as Weak according to the quality assessment tool with sampling practices (self-referred participants) and poor reporting of participant withdrawals/drop-outs the predominant reasons for Weak ratings. A wide variety of extrinsic strategies were reported with music, music videos, immersive virtual reality, outdoor exercise, caffeine, high-to-low pattern of exercise intensity, self-selected exercise intensity, and manipulation of self-efficacy offering promise as suitable strategies to positively change how people feel during exercise. Systematic Review Registration: https://osf.io/jbh8v/.

Fluorescent copolymer aggregate sensor for lithium chloride.

We report a copolymeric fluorescent sensor that is selective for lithium chloride. The two constituent polymers comprise pendent triphenylethylene (TPE) moieties for aggregate induced emission (AIE) along with either strapped-calix[4]pyrrole or secondary ammonium groups that drive aggregation via self-assembly upon polymer mixing. Addition of LiCl in acetonitrile disrupts the strapped-calix[4]pyrrole/secondary ammonium chloride salt host-guest crosslinks leading to disaggregation of the polymer chains and a decrease in TPE emission. The lack of AIE perturbation upon addition of NaCl, KCl, MgCl2 or CaCl2 provides for high selectivity for LiCl relative to potential interferants. This supramolecular dual polymer approach could serve as a complement to more traditional sensor systems.

Excited State Nonadiabatic Molecular Dynamics of Hot Electron Addition to Water Clusters in the Ultrafast Femtosecond Regime.

Dissociative electron attachment (DEA) reactions of water result in the production of hydrogen atoms and hydroxide anions. This has been studied for a long time and is relatively slow in liquid water for thermalized hydrated electrons but much faster with a higher-energy electron. Here, we probe the nonadiabatic molecular dynamics after the addition of a hot electron (6-7 eV) to a neutral water cluster (H2O)n, where n = 2-12, considering the 0-100 fs time scale using the fewest switches surface hopping method, in conjunction with ab initio molecular dynamics and the Tamm-Dancoff approximation density functional theory method. The nonadiabatic DEA occurs within 10-60 fs, and with high probability, giving H + OH- above an energy threshold. This is faster than time scales estimated previously for autoionization or adiabatic DEA. The change in threshold energy with cluster size is modest, ranging from 6.6 to 6.9 eV. Dissociation on a femtosecond time scale is consistent with pulsed radiolysis experiments.

Affective Responses to Increasing- and Decreasing-Intensity Resistance Training Protocols.

This study compared the effects of an increasing-intensity (UP) and a decreasing-intensity (DOWN) resistance training protocol on affective responses across six training sessions. Novice participants (Mage 43.5 ± 13.7 years) were randomly assigned to UP (n = 18) or DOWN (n = 17) resistance training groups. Linear mixed-effects models showed that the evolution of affective valence within each training session was significantly moderated by the group (b = -0.45, p ≤ .001), with participants in the UP group reporting a decline in pleasure during each session (b = -0.82) and the DOWN group reporting an improvement (b = 0.97; ps < .001). Remembered pleasure was significantly higher in the DOWN group compared to the UP group (b = 0.57, p = .004). These findings indicate that a pattern of decreasing intensity throughout a resistance exercise session can elicit more positive affective responses and retrospective affective evaluations of resistance training.

High-efficiency gold recovery by additive-induced supramolecular polymerization of ß-cyclodextrin.

Developing an eco-friendly, efficient, and highly selective gold-recovery technology is urgently needed in order to maintain sustainable environments and improve the utilization of resources. Here we report an additive-induced gold recovery paradigm based on precisely controlling the reciprocal transformation and instantaneous assembly of the second-sphere coordinated adducts formed between ß-cyclodextrin and tetrabromoaurate anions. The additives initiate a rapid assembly process by co-occupying the binding cavity of ß-cyclodextrin along with the tetrabromoaurate anions, leading to the formation of supramolecular polymers that precipitate from aqueous solutions as cocrystals. The efficiency of gold recovery reaches 99.8% when dibutyl carbitol is deployed as the additive. This cocrystallization is highly selective for square-planar tetrabromoaurate anions. In a laboratory-scale gold-recovery protocol, over 94% of gold in electronic waste was recovered at gold concentrations as low as 9.3 ppm. This simple protocol constitutes a promising paradigm for the sustainable recovery of gold, featuring reduced energy consumption, low cost inputs, and the avoidance of environmental pollution.

Color-Tunable Upconversion-Emission Switch Based on Cocrystal-to-Cocrystal Transformation.

Cocrystal engineering, involving the assembly of two or more components into a highly ordered solid-state superstructure, has emerged as a popular strategy for tuning the photophysical properties of crystalline materials. The reversible co-assembly and disassembly of multicomponent cocrystals and their reciprocal transformation in the solid state remain challenging objectives. Herein, we report a color-tunable upconversion-emission switch based on the interconversion between two cocrystals. One red- and one yellow-emissive cocrystal, composed of an electron-deficient naphthalenediimide-based triangular macrocycle and different electron donors, have been obtained. The red- and yellow-emissive cocrystals undergo reversible transformations on exchanging the electron donors. Benefiting from intermolecular charge transfer interactions, the two cocrystals display superior two-photon excited upconversion emission. Accompanying the interconversion of the two cocrystals, their luminescent color changes between red and yellow, forming a dual-color upconversion-emission switch. This research provides a rare yet critical example involving precise control of cocrystal-to-cocrystal transformation and affords a reference for fabricating color-tunable nonlinear optical materials in the solid state.

Green and Pleasant Lands: The Affective and Cerebral Hemodynamic Effects of Presence in Virtual Environments During Exercise.

Pleasant exercise experiences increase the likelihood of exercise adherence, and innovative strategies to promote consistently pleasant exercise experiences are needed. In this study we compared a novel nature-based virtual reality environment, a nature-based 360° video, and a control condition to test the hypothesis that greater presence in virtual space would promote positive affective experiences during exercise. Moreover, we assessed prefrontal cerebral hemodynamics using near infrared spectroscopy to explore possible neural underpinnings of dissociative strategies during exercise. Twelve participants (M = 26.2, SD = 7.7 years; M BMI = 25.5, SD = 5.2 kg/m2) completed a maximal aerobic test and three exercise conditions (Control, Virtual Reality [VR], and 360° video). The two experimental conditions differed in terms of the participants' sense of presence (VR eliciting greatest presence), and all conditions utilized similar exercise intensity. The VR condition setting was a virtual mountain forest trail, and the 360° video was of a forest road. The 360° video was perceived as the most distracting (p = .023, d = 1.07), pleasant (p = .007, d = .75), and enjoyable (p = .029; d = .82) condition. ΔHbDiff data indicated that the control condition caused the greatest prefrontal brain activation (p = .008, d = .84). Presence was not a salient factor in distracting participants from bodily sensations during exercise, but immersion in a stimulus was. These results provide support for using head-mounted displays during exercise as a strategy to increase pleasure, with practical implications for practitioners, researchers, and individuals.

Utilizing Ultraviolet Photons to Generate Single-Photon Emitters in Semiconductor Monolayers.

The understanding and controlled creation of atomic defects in semiconductor transition metal dichalcogenides (TMDs) are highly relevant to their applications in high-performance quantum optics and nanoelectronic devices. Here, we demonstrate a versatile approach in generating single-photon emitters in MoS2 monolayers using widely attainable UV light. We discover that only defects engendered by UV photons in vacuum exhibit single-photon-emitter characteristics, whereas those created in air lack quantum emission attributes. In combination with theoretical calculations, we assign the defects generated in vacuum to unpassivated sulfur vacancies, whose highly localized midgap states give rise to single-photon emission. In contrast, UV irradiation of the MoS2 monolayers in air results in oxygen-passivated sulfur vacancies, whose optical properties are likely governed by their pristine band-to-defect band optical transitions. These findings suggest that widely available light sources such as UV light can be utilized for creating quantum photon sources in TMDs.

Atomic-Scale View of Redox Induced Changes for Monolayer MoOx on α-TiO2(110) with Chemical-State Sensitivity.

Supported molybdenum oxide (MoOx) plays an important role in catalytic transformations from alcohol dehydrogenation to transesterification. During these reactions, molybdenum and oxygen surface species undergo structural and chemical changes. A detailed, chemical-state specific, atomic-scale structural analysis of the catalyst under redox conditions is important for improving catalytic properties. In this study, a monolayer of Mo grown on α-TiO2(110) by atomic-layer deposition is analyzed by X-ray standing wave (XSW) excited X-ray photoelectron spectroscopy (XPS). The chemical shifts for Mo 2p3/2 and O 1s peaks are used to distinguish Mo6+ from Mo4+ and surface O from bulk O. Excitation of XPS by XSW allows pinpointing the location of these surface species relative to the underlying substrate lattice. Measured 3D composite atomic density maps for the oxidized and reduced interfaces compare well with our density functional theory models and collectively create a unique view of the redox-driven dynamics for this complex catalytic structure.

Atomic-Site-Specific Surface Valence-Band Structure from X-Ray Standing-Wave Excited Photoemission.

X-ray standing-wave (XSW) excited photoelectron emission was used to measure the site-specific valence band (VB) for ½ monolayer (ML) Pt grown on a SrTiO_{3} (001) surface. The XSW induced modulations in the core level (CL), and VB photoemission from the surface and substrate atoms were monitored for three hkl substrate Bragg reflections. The XSW CL analysis shows the Pt to have a face-centered-cubic-like cube-on-cube epitaxy with the substrate. The XSW VB information compares well to a density functional theory calculated projected density of states from the surface and substrate atoms. Overall, this Letter represents a novel method for determining the contribution to the density of states by valence electrons from specific atomic surface sites.

Multipurpose made colorimetric materials for amines, pH change and metal ion detection.

Sensors are routinely developed for specific applications, but multipurpose sensors are challenging, due to stability and poor functional design. We report organic materials that operate in solution and gas phase. They show a strong response behaviour to at least three types of environmental changes: pH, amine and metal ion binding/detection. We have confirmed and validated our findings using various analytical and computational methods. We found that the changes in polarity of the solvent and pH not only red shift the tail of the absorption spectra, but also extend the peak optical absorption of these structures by up to 100 nm, with consequential effects on the optical gap and colour changes of the materials. Acid-base response has been studied by spectrophotometric titrations with trifluoroacetic acid (TFA) and triethyl amine (TEA). The experiments show excellent reversibility with greater sensitivity to base than acid for all compounds. Analysis into metal sensing using Zn(ii) and Cu(ii) ions as analytes show that the materials can successfully bind the cations forming stable complexes. Moreover, a strong suppression of signal with copper gives an operative modality to detect the copper ion as low as 2.5 × 10-6 M. The formation of the metal complexes was also confirmed by growing crystals using a slow diffusion method; subsequent single crystal X-ray analysis reveals the ratio of ligand to metal to be 2 to 1. To test sensitivity towards various amine vapours, paper-based sensors have been fabricated. The sensors show a detection capability at 1 ppm of amine concentration. We have employed CIE L*a*b* colour space as the evaluation method, this provides numeric comparison of the samples from different series and allows comparison of small colour differences, which are generally undetectable by the human-eye. It shows that the CIE L*a*b* method can assess both sensitivity to a particular class of analytes and a specificity response to individual amines in this subclass offering an inexpensive and versatile methodology.

Localized π Surface States on 2D Molybdenum Disulfide from Carbene-Functionalization as a Qubit Design Strategy.

Surface chemistry is increasingly important for a number of applications, from catalysis to molecular qubits. For the qubit application, it is imperative that the energy levels of surface species involved in the process of interest are energetically distinct-that is addressable and not buried below or coincident with the substrate energy levels. One way to afford this is through chemical functionalization with derivatives that impart the property of choice to the interface. In this Letter, we report on the nature of the bond between a carbene moiety and an MoS2 surface. With density functional theory (DFT) and spin-polarized calculations, we first observe states in the band structure that pertain to the carbene group and then prove their origin. Importantly, we find localized π-states in the band gap that are due to π-electrons that are part of a diene attached to the carbene carbon and are not available in bonding configurations without the π conjugation. These lead to open-shell monocationic structures involving midgap HOMOs with densities on the carbene moiety. Both neutral and cationic forms of the carbenes are energetically separate from the MoS2 substrate, thus useful for optical manipulation. We explore several different choices of the carbene moieties, and show that those based on fused thiophene and bithiophene structures are the most favorable for localization, while purely carbon-based aromatic structures lead to states that are delocalized onto the MoS2 and thus less useful. These findings are potentially of interest to the design and synthesis of future molecular qubit candidates for device fabrication.

Regiospecific N-alkyl substitution tunes the molecular packing of high-performance non-fullerene acceptors.

The rapid development of non-fullerene acceptors (NFAs) with strong near-infrared absorption has led to remarkably enhanced short-circuit current density (Jsc) values in organic solar cells (OSCs). NFAs based on the benzotriazole (Bz) fused-ring π-core have great potential in delivering both high Jsc and decent open-circuit voltage values due to their strong intramolecular charge transfer with reasonably low energy loss. In this work, we have designed and synthesized a series of Bz-based NFAs, PN6SBO-4F, AN6SBO-4F and EHN6SEH-4F, via regiospecific N-alkyl engineering based on the high-performance NFA mBzS-4F that was reported previously. The molecular packing of mBzS-4F, AN6SBO-4F, and EHN6SEH-4F single crystals was analyzed using X-ray crystallography in order to provide a comprehensive understanding of the correlation between the molecular structure, the charge-transporting properties, and the solar cell performance. Compared with the typical honeycomb single-crystal structure of Y6 derivatives, these NFAs exhibit distinctly different molecular packing patterns. The strong interactions of terminal indanone groups in mBzS-4F and the J-aggregate-like packing in EHN6SEH-4F lead to the formation of ordered 3D networks in single-crystals with channels for efficient charge transport. Consequently, OSCs based on mBzS-4F and EHN6SEH-4F show efficient photon-to-current conversions, achieving the highest power conversion efficiency of 17.48% with a Jsc of 28.83 mA cm-2.

Synthesis and Structure-Activity Characterization of a Single-Site MoO2 Catalytic Center Anchored on Reduced Graphene Oxide.

Molecularly derived single-site heterogeneous catalysts can bridge the understanding and performance gaps between conventional homogeneous and heterogeneous catalysis, guiding the rational design of next-generation catalysts. While impressive advances have been made with well-defined oxide supports, the structural complexity of other supports and the nature of the grafted surface species present an intriguing challenge. In this study, single-site Mo(═O)2 species grafted onto reduced graphene oxide (rGO/MoO2) are characterized by XPS, DRIFTS, powder XRD, N2 physisorption, NH3-TPD, aqueous contact angle, active site poisoning assay, Mo EXAFS, model compound single-crystal XRD, DFT, and catalytic performance. NH3-TPD reveals that the anchored MoO2 moiety is not strongly acidic, while Mo 3d5/2 XPS assigns the oxidation state as Mo(VI), and XRD shows little rGO periodicity change on MoO2 grafting. Contact angle analysis shows that MoO2 grafting consumes rGO surface polar groups, yielding a more hydrophobic surface. The rGO/MoO2 DRIFTS assigns features at 959 and 927 cm-1 to the symmetric and antisymmetric Mo═O stretching modes, respectively, of an isolated cis-(O═Mo═O) moiety, in agreement with DFT computation. Moreover, the Mo EXAFS rGO/MoO2 structural data are consistent with isolated (C-O)2-Mo(═O)2 species having two Mo═O bonds and two Mo-O bonds at distances of 1.69(3) and 1.90(3) Å, respectively. rGO/MoO2 is also more active than the previously reported AC/MoO2 catalyst, with reductive carbonyl coupling TOFs approaching 1.81 × 103 h-1. rGO/MoO2 is environmentally robust and multiply recyclable with 69 ± 2% of the Mo sites catalytically significant. Overall, rGO/MoO2 is a structurally well-defined and versatile single-site Mo(VI) dioxo heterogeneous catalytic system.

Selective Separation of Lithium Chloride by Organogels Containing Strapped Calix[4]pyrroles.

Reported herein are two functionalized crown ether strapped calix[4]pyrroles, H1 and H2. As inferred from competitive salt binding experiments carried out in nitrobenzene-d5 and acetonitrile-d3, these hosts capture LiCl selectively over four other test salts, viz. NaCl, KCl, MgCl2, and CaCl2. Support for the selectivity came from density functional theory (DFT) calculations carried out in a solvent continuum. These theoretical analyses revealed a higher innate affinity for LiCl in the case of H1, but a greater selectivity relative to NaCl in the case of H2, recapitulating that observed experimentally. Receptors H1 and H2 were outfitted with methacrylate handles and subject to copolymerization with acrylate monomers and cross-linkers to yield gels, G1 and G2, respectively. These two gels were found to adsorb lithium chloride preferentially from an acetonitrile solution containing a mixture of LiCl, NaCl, KCl, MgCl2, and CaCl2 and then release the lithium chloride in methanol. The gels could then be recycled for reuse in the selective adsorption of LiCl. As such, the present study highlights the use of solvent polarity switching to drive separations with potential applications in lithium purification and recycling.

PCage: Fluorescent Molecular Temples for Binding Sugars in Water.

The development of synthetic receptors that recognize carbohydrates in water with high selectivity and specificity is challenging on account of their structural complexity and strong hydrophilicity. Here, we report on the design and synthesis of two pyrene-based, temple-shaped receptors for the recognition of a range of common sugars in water. These receptors rely on the use of two parallel pyrene panels, which serve as roofs and floors, capable of forming multiple [C-H···π] interactions with the axially oriented C-H bonds on glycopyranosyl rings in the carbohydrate-based substrates. In addition, eight polarized pyridinium C-H bonds, projecting from the roofs and floors of the temple receptors toward the binding cavities, form [C-H···O] hydrogen bonds, with the equatorially oriented OH groups on the sugars located inside the hydrophobic cavities. Four para-xylylene pillars play a crucial role in controlling the distance between the roof and floor. These temple receptors are highly selective for the binding of glucose and its derivatives. Furthermore, they show enhanced fluorescence upon binding with glucose in water, a property which is useful for glucose-sensing in aqueous solution.