Covalent-Frameworked 2D Crown Ether with Chemical Multifunctionality.

Here, we present the synthesis and characterization of a novel 2D crystalline framework, named C2O, which mainly consists of carbon and oxygen in a 2:1 molar ratio and features crown ether holes in its skeletal structure. The covalent-frameworked 2D crown ether can be synthesized on a gram-scale and exhibits fine chemical stability in various environments, including acid, base, and different organic solvents. The C2O efficiently activates KI through the strong coordination of K+ with crown ether holes in a rigid framework, which enhances the nucleophilicity of I- and significantly improves its catalytic activity for CO2 fixation with epoxides. The presence of C2O with KI results in remarkable increases in CO2 conversion from 5.7% to 99.9% and from 2.9% to 74.2% for epichlorohydrin and allyl glycidyl ether, respectively. Moreover, C2O possesses both electrophilic and nucleophilic sites at the edge of its framework, allowing for the customization of physicochemical properties by a diverse range of chemical modifications. Specifically, incorporating allyl glycidyl ether (AGE) as an electrophile or ethoxyethylamine (EEA) as a nucleophile into C2O enables the synthesis of C2O-AGE or C2O-EEA, respectively. These modified frameworks exhibit improved conversions of 97.2% and 99.9% for CO2 fixation with allyl glycidyl ether, outperforming unmodified C2O showing a conversion of 74.2%. This newly developed scalable, durable, and customizable covalent framework holds tremendous potential for the design and preparation of outstanding materials with versatile functionalities, rendering them highly attractive for a wide range of applications.

Small, solubilized platinum nanocrystals consist of an ordered core surrounded by mobile surface atoms.

In situ structures of Platinum (Pt) nanoparticles (NPs) can be determined with graphene liquid cell transmission electron microscopy. Atomic-scale three-dimensional structural information about their physiochemical properties in solution is critical for understanding their chemical function. We here analyze eight atomic-resolution maps of small (<3 nm) colloidal Pt NPs. Their structures are composed of an ordered crystalline core surrounded by surface atoms with comparatively high mobility. 3D reconstructions calculated from cumulative doses of 8500 and 17,000 electrons/pixel, respectively, are characterized in terms of loss of atomic densities and atomic displacements. Less than 5% of the total number of atoms are lost due to dissolution or knock-on damage in five of the structures analyzed, whereas 10-16% are lost in the remaining three. Less than 5% of the atomic positions are displaced due to the increased electron irradiation in all structures. The surface dynamics will play a critical role in the diverse catalytic function of Pt NPs and must be considered in efforts to model Pt NP function computationally.

Promoting Self-Efficacy of Individuals With Autism in Practicing Social Skills in the Workplace Using Virtual Reality and Physiological Sensors: Mixed Methods Study.

BACKGROUND: Individuals with autism often experience heightened anxiety in workplace environments because of challenges in communication and sensory overload. As these experiences can result in negative self-image, promoting their self-efficacy in the workplace is crucial. Virtual reality (VR) systems have emerged as promising tools for enhancing the self-efficacy of individuals with autism in navigating social scenarios, aiding in the identification of anxiety-inducing situations, and preparing for real-world interactions. However, there is limited research exploring the potential of VR to enhance self-efficacy by facilitating an understanding of emotional and physiological states during social skills practice. OBJECTIVE: This study aims to develop and evaluate a VR system that enabled users to experience simulated work-related social scenarios and reflect on their behavioral and physiological data through data visualizations. We intended to investigate how these data, combined with the simulations, can support individuals with autism in building their self-efficacy in social skills. METHODS: We developed WorkplaceVR, a comprehensive VR system designed for engagement in simulated work-related social scenarios, supplemented with data-driven reflections of users' behavioral and physiological responses. A within-subject deployment study was subsequently conducted with 14 young adults with autism to examine WorkplaceVR's feasibility. A mixed methods approach was used, compassing pre- and postsystem use assessments of participants' self-efficacy perceptions. RESULTS: The study results revealed WorkplaceVR's effectiveness in enhancing social skills and self-efficacy among individuals with autism. First, participants exhibited a statistically significant increase in perceived self-efficacy following their engagement with the VR system (P=.02). Second, thematic analysis of the interview data confirmed that the VR system and reflections on the data fostered increased self-awareness among participants about social situations that trigger their anxiety, as well as the behaviors they exhibit during anxious moments. This increased self-awareness prompted the participants to recollect their related experiences in the real world and articulate anxiety management strategies. Furthermore, the insights uncovered motivated participants to engage in self-advocacy, as they wanted to share the insights with others. CONCLUSIONS: This study highlights the potential of VR simulations enriched with physiological and behavioral sensing as a valuable tool for augmenting self-efficacy in workplace social interactions for individuals with autism. Data reflection facilitated by physiological sensors helped participants with autism become more self-aware of their emotions and behaviors, advocate for their characteristics, and develop positive self-beliefs.

Method for 3D atomic structure determination of multi-element nanoparticles with graphene liquid-cell TEM.

Determining the 3D atomic structures of multi-element nanoparticles in their native liquid environment is crucial to understanding their physicochemical properties. Graphene liquid cell (GLC) TEM offers a platform to directly investigate nanoparticles in their solution phase. Moreover, exploiting high-resolution TEM images of single rotating nanoparticles in GLCs, 3D atomic structures of nanoparticles are reconstructed by a method called "Brownian one-particle reconstruction". We here introduce a 3D atomic structure determination method for multi-element nanoparticle systems. The method, which is based on low-pass filtration and initial 3D model generation customized for different types of multi-element systems, enables reconstruction of high-resolution 3D Coulomb density maps for ordered and disordered multi-element systems and classification of the heteroatom type. Using high-resolution image datasets obtained from TEM simulations of PbSe, CdSe, and FePt nanoparticles that are structurally relaxed with first-principles calculations in the graphene liquid cell, we show that the types and positions of the constituent atoms are precisely determined with root mean square displacement values less than 24 pm. Our study suggests that it is possible to investigate the 3D atomic structures of synthesized multi-element nanoparticles in liquid phase.

Complex ligand adsorption on 3D atomic surfaces of synthesized nanoparticles investigated by machine-learning accelerated ab initio calculation.

Nanoparticle surfaces are passivated by surface-bound ligands, and their adsorption on synthesized nanoparticles is complicated because of the intricate and low-symmetry surface structures. Thus, it is challenging to precisely investigate ligand adsorption on synthesized nanoparticles. Here, we applied machine-learning-accelerated ab initio calculation to experimentally resolved 3D atomic structures of Pt nanoparticles to analyze the complex adsorption behavior of polyvinylpyrrolidone (PVP) ligands on synthesized nanoparticles. Different angular configurations of large-sized ligands are thoroughly investigated to understand the adsorption behavior on various surface-exposed atoms with intrinsic low-symmetry. It is revealed that the ligand binding energy (Eads) of the large-sized ligand shows a weak positive relationship with the generalized coordination number . This is because the strong positive relationship of short-range direct bonding (Ebind) is attenuated by the negative relationship of long-range van der Waals interaction (EvdW). In addition, it is demonstrated that the PVP ligands prefer to adsorb where the long-range vdW interaction with the surrounding surface structure is maximized. Our results highlight the significant contribution of vdW interactions and the importance of the local geometry of surface atoms to the adsorption behavior of large-sized ligands on synthesized nanoparticle surfaces.

Observation of H2 Evolution and Electrolyte Diffusion on MoS2 Monolayer by In Situ Liquid-Phase Transmission Electron Microscopy.

Unit-cell-thick MoS2 is a promising electrocatalyst for the hydrogen evolution reaction (HER) owing to its tunable catalytic activity, which is determined based on the energetics and molecular interactions of different types of HER active sites. Kinetic responses of MoS2 active sites, including the reaction onset, diffusion of the electrolyte and H2 bubbles, and continuation of these processes, are important factors affecting the catalytic activity of MoS2 . Investigating these factors requires a direct real-time analysis of the HER occurring on spatially independent active sites. Herein, the H2 evolution and electrolyte diffusion on the surface of MoS2 are observed in real time by in situ electrochemical liquid-phase transmission electron microscopy (LPTEM). Time-dependent LPTEM observations reveal that different types of active sites are sequentially activated under the same conditions. Furthermore, the electrolyte flow to these sites is influenced by the reduction potential and site geometry, which affects the bubble detachment and overall HER activity of MoS2 .

Super fine cerium hydroxide abrasives for SiO2 film chemical mechanical planarization performing scratch free.

Face-centered-cubic crystallized super-fine (~ 2 nm in size) wet-ceria-abrasives are synthesized using a novel wet precipitation process that comprises a Ce4+ precursor, C3H4N2 catalyst, and NaOH titrant for a synthesized termination process at temperature of at temperature of 25 °C. This process overcomes the limitations of chemical-mechanical-planarization (CMP)-induced scratches from conventional dry ceria abrasives with irregular surfaces or wet ceria abrasives with crystalline facets in nanoscale semiconductor devices. The chemical composition of super-fine wet ceria abrasives depends on the synthesis termination pH, that is, Ce(OH)4 abrasives at a pH of 4.0-5.0 and a mixture of CeO2 and Ce(OH)4 abrasives at a pH of 5.5-6.5. The Ce(OH)4 abrasives demonstrate better abrasive stability in the SiO2-film CMP slurry than the CeO2 abrasives and produce a minimum abrasive zeta potential (~ 12 mV) and a minimum secondary abrasive size (~ 130 nm) at the synthesis termination pH of 5.0. Additionally, the abrasive stability of the SiO2-film CMP slurry that includes super-fine wet ceria abrasives is notably sensitive to the CMP slurry pH; the best abrasive stability (i.e., a minimum secondary abrasive size of ~ 130 nm) is observed at a specific pH (6.0). As a result, a maximum SiO2-film polishing rate (~ 524 nm/min) is achieved at pH 6.0, and the surface is free of stick-and-slip type scratches.

Correlating 3D Surface Atomic Structure and Catalytic Activities of Pt Nanocrystals.

Active sites and catalytic activity of heterogeneous catalysts is determined by their surface atomic structures. However, probing the surface structure at an atomic resolution is difficult, especially for solution ensembles of catalytic nanocrystals, which consist of heterogeneous particles with irregular shapes and surfaces. Here, we constructed 3D maps of the coordination number (CN) and generalized CN (CN_) for individual surface atoms of sub-3 nm Pt nanocrystals. Our results reveal that the synthesized Pt nanocrystals are enclosed by islands of atoms with nonuniform shapes that lead to complex surface structures, including a high ratio of low-coordination surface atoms, reduced domain size of low-index facets, and various types of exposed high-index facets. 3D maps of CN_ are directly correlated to catalytic activities assigned to individual surface atoms with distinct local coordination structures, which explains the origin of high catalytic performance of small Pt nanocrystals in important reactions such as oxygen reduction reactions and CO electro-oxidation.

SINGLE: Atomic-resolution structure identification of nanocrystals by graphene liquid cell EM.

Analysis of the three-dimensional (3D) structures of nanocrystals with solution-phase transmission electron microscopy is beginning to reveal their unique physiochemical properties. We developed a "one-particle Brownian 3D reconstruction method" based on imaging of ensembles of colloidal nanocrystals using graphene liquid cell electron microscopy. Projection images of differently rotated nanocrystals are acquired using a direct electron detector with high temporal (<2.5 ms) resolution and analyzed to obtain an ensemble of 3D reconstructions. Here, we introduce computational methods required for successful atomic-resolution 3D reconstruction: (i) tracking of the individual particles throughout the time series, (ii) subtraction of the interfering background of the graphene liquid cell, (iii) identification and rejection of low-quality images, and (iv) tailored strategies for 2D/3D alignment and averaging that differ from those used in biological cryo-electron microscopy. Our developments are made available through the open-source software package SINGLE.

Reversible disorder-order transitions in atomic crystal nucleation.

Nucleation in atomic crystallization remains poorly understood, despite advances in classical nucleation theory. The nucleation process has been described to involve a nonclassical mechanism that includes a spontaneous transition from disordered to crystalline states, but a detailed understanding of dynamics requires further investigation. In situ electron microscopy of heterogeneous nucleation of individual gold nanocrystals with millisecond temporal resolution shows that the early stage of atomic crystallization proceeds through dynamic structural fluctuations between disordered and crystalline states, rather than through a single irreversible transition. Our experimental and theoretical analyses support the idea that structural fluctuations originate from size-dependent thermodynamic stability of the two states in atomic clusters. These findings, based on dynamics in a real atomic system, reshape and improve our understanding of nucleation mechanisms in atomic crystallization.

Echocardiographic versus angiographic measurement of the aortic valve annulus in children undergoing balloon aortic valvuloplasty: method affects outcomes.

OBJECTIVE: Operators are mindful of the balloon-to-aortic annulus ratio when performing balloon aortic valvuloplasty. The method of measurement of the aortic valve annulus has not been standardised. METHODS AND RESULTS: Patients who underwent aortic valvuloplasty at two paediatric centres between 2007 and 2014 were included. The valve annulus measured by echocardiography and angiography was used to calculate the balloon-to-aortic annulus ratio and measurements were compared. The primary endpoint was an increase in aortic insufficiency by ≥2 degrees. Ninety-eight patients with a median age at valvuloplasty of 2.1 months (Interquartile range (IQR): 0.2-105.5) were included. The angiographic-based annulus was 8.2 mm (IQR: 6.8-16.0), which was greater than echocardiogram-based annulus of 7.5 mm (IQR: 6.1-14.8) (p < 0.001). This corresponded to a significantly lower angiographic balloon-to-aortic annulus ratio of 0.9 (IQR: 0.9-1.0), compared to an echocardiographic ratio of 1.1 (IQR: 1.0-1.1) (p < 0.001). The degree of discrepancy in measured diameter increased with smaller valve diameters (p = 0.041) and in neonates (p = 0.044). There was significant disagreement between angiographic and echocardiographic balloon-to-aortic annulus ratio measures regarding "High" ratio of >1.2, with angiographic ratio flagging only 2/12 (16.7%) of patients flagged by echocardiographic ratio as "High" (p = 0.012). Patients who had an increase in the degree of aortic insufficiency post valvuloplasty, only 3 (5.5%) had angiographic ratio > 1.1, while 21 (38%) had echocardiographic ratio >1.1 (p < 0.001). Patients with resultant ≥ moderate insufficiency more often had an echocardiographic ratio of >1.1 than angiographic ratio of >1.1 There was no association between increase in balloon-to-aortic annulus ratio and gradient reduction. CONCLUSIONS: Angiographic measurement is associated with a greater measured aortic valve annulus and the development of aortic insufficiency. Operators should use caution when relying solely on angiographic measurement when performing balloon aortic valvuloplasty.

Critical differences in 3D atomic structure of individual ligand-protected nanocrystals in solution.

Precise three-dimensional (3D) atomic structure determination of individual nanocrystals is a prerequisite for understanding and predicting their physical properties. Nanocrystals from the same synthesis batch display what are often presumed to be small but possibly important differences in size, lattice distortions, and defects, which can only be understood by structural characterization with high spatial 3D resolution. We solved the structures of individual colloidal platinum nanocrystals by developing atomic-resolution 3D liquid-cell electron microscopy to reveal critical intrinsic heterogeneity of ligand-protected platinum nanocrystals in solution, including structural degeneracies, lattice parameter deviations, internal defects, and strain. These differences in structure lead to substantial contributions to free energies, consequential enough that they must be considered in any discussion of fundamental nanocrystal properties or applications.

Redox-Sensitive Facet Dependency in Etching of Ceria Nanocrystals Directly Observed by Liquid Cell TEM.

Defining the redox activity of different surface facets of ceria nanocrystals is important for designing an efficient catalyst. Especially in liquid-phase reactions, where surface interactions are complicated, direct investigation in a native environment is required to understand the facet-dependent redox properties. Using liquid cell TEM, we herein observed the etching of ceria-based nanocrystals under the control of redox-governing factors. Direct nanoscale observation reveals facet-dependent etching kinetics, thus identifying the specific facet ({100} for reduction and {111} for oxidation) that governs the overall etching under different chemical conditions. Under each redox condition, the contribution of the predominant facet increases as the etching reactivity increases.

The combined effects of yogurt and exercise in healthy adults: Implications for biomarkers of depression and cardiovascular diseases.

Several studies have reported individual benefits of yogurt and exercise on health; however, their combined effects remain unclear. Twenty-four healthy individuals participated in the study and were randomly assigned to the following four groups: control, yogurt, exercise, and combination. The participants consumed yogurt and exercised for 2 weeks, and we examined the combined effects of yogurt and exercise on physiological biomarkers. Individually, yogurt and exercise did not exert a significant effect on biomarkers of depression or cardiovascular disease, although vitamin D levels increased in the exercise group. However, in the combination group, serotonin levels increased, while levels of triglycerides and high-sensitivity C-reactive protein, which are biomarkers for cardiovascular diseases, decreased. In conclusion, the results of the study showed that, in healthy individuals, a combination of yogurt and exercise led to greater increases in serotonin levels and reductions in triglyceride and high-sensitivity C-reactive protein levels, relative to those observed for yogurt or exercise alone; therefore, this combination could have implications for the prevention of depression and cardiovascular disease.

Effects of Cervical Extension on Deformation of Intervertebral Disk and Migration of Nucleus Pulposus.

BACKGROUND: We theorized that active cervical extension should influence the position of the nucleus pulposus (NP) within the intervertebral disk (IVD) in the sagittal plane. Although several studies on the lumbar IVD have been conducted, there are no quantitative data for in vivo positional changes of the NP in the cervical IVD. OBJECTIVE: To evaluate the influence and mechanism of cervical extension on the deformation and migration of IVD and NP in the sagittal plane and understand underlying mechanisms of the extension maneuver. DESIGN: Asymptomatic subjects underwent magnetic resonance imaging while supine with their cervical spines in neutral and extended positions. SETTING: Academic medical center. PARTICIPANTS: Ten young, healthy male participants (age range 19-30 years; mean 22.4 ± 1.64 years). METHODS: T2-weighted sagittal images from C3-C4 to C6-C7 of subjects in both neutral and extension positions were analyzed. MAIN OUTCOME MEASUREMENTS: Deformation of IVD and positional change of NP were quantified and compared between neutral and extension positions. Intersegmental angles between vertebrae, horizontal positions of anterior and posterior IVD and NP margins, IVD outer and inner heights, and sagittal morphology of NP were quantified and compared between the neutral and extension positions. Correlations between the measured parameters and segmental extension angle were also investigated. RESULTS: Anterior and posterior IVD margins moved posteriorly with respect to the vertebral body in extension. Both NP margins remained unchanged relative to the vertebral body but moved anteriorly with respect to the IVD. IVD outer and inner heights in the anterior region increased in extension, and morphological changes of the NP were less noticeable when compared with its relative migration within the IVD. Most of the intradiskal changes were linearly correlated with the segmental extension angle. CONCLUSIONS: Cervical extension induces anterior migration of the NP away from the posterior disk margin and may have a clinical effect on diskogenic neck pain resulting from internal disk disruption. LEVEL OF EVIDENCE: Not applicable.

Relation of Aortic Valve Morphologic Characteristics to Aortic Valve Insufficiency and Residual Stenosis in Children With Congenital Aortic Stenosis Undergoing Balloon Valvuloplasty.

Aortic valve morphology has been invoked as intrinsic to outcomes of balloon aortic valvuloplasty (BAV) for congenital aortic valve stenosis. We sought to use aortic valve morphologic features to discriminate between valves that respond favorably or unfavorably to BAV, using aortic insufficiency (AI) as the primary outcome. All patients who underwent BAV at 2 large-volume pediatric centers from 2007 to 2014 were reviewed. Morphologic features assessed on pre-BAV echo included valve pattern (unicuspid, functional bicuspid, and true bicuspid), leaflet fusion length, leaflet excursion angle, and aortic valve opening area and on post-BAV echo included leaflet versus commissural tear. Primary end point was increase in AI (AI+) of ≥2°. Eighty-nine patients (median age 0.2 years) were included in the study (39 unicuspid, 41 functional bicuspid, and 9 true bicuspid valves). Unicuspid valves had a lower opening area (p <0.01) and greater fusion length (p = 0.01) compared with functional and true bicuspid valves. Valve gradient pre-BAV and post-BAV were not different among valve patterns. Of the 16 patients (18%) with AI+, 14 had leaflet tears (odds ratio 13.9, 3.8 to 50). True bicuspid valves had the highest rate (33%) of AI+. On multivariate analysis, leaflet tears were associated with AI+, with larger opening area pre-BAV and lower fusion length pre-BAV. AI+ was associated with larger pre-BAV opening area. Gradient relief was associated with reduced angle of excursion. Valve morphology influences outcomes after BAV. Valves with lesser fusion and larger valve openings have higher rates of leaflet tears which in turn are associated with AI.