Advancing the Mechanosensitivity of Atropisomeric Diarylethene Mechanophores through a Lever-Arm Effect.

Understanding structure-mechanical activity relationships (SMARs) in polymer mechanochemistry is essential for the rational design of mechanophores with desired properties, yet SMARs in noncovalent mechanical transformations remain relatively underexplored. In this study, we designed a subset of diarylethene mechanophores based on a lever-arm hypothesis and systematically investigated their mechanical activity toward a noncovalent-yet-chemical conversion of atropisomer stereochemistry. Results from Density functional theory (DFT) calculations, single-molecule force spectroscopy (SMFS) measurements, and ultrasonication experiments collectively support the lever-arm hypothesis and confirm the exceptional sensitivity of chemo-mechanical coupling in these atropisomers.

Ultrasound-Controlled Prodrug Activation: Emerging Strategies in Polymer Mechanochemistry and Sonodynamic Therapy.

Ultrasound has gained prominence in biomedical applications due to its noninvasive nature and ability to penetrate deep tissue with spatial and temporal resolution. The burgeoning field of ultrasound-responsive prodrug systems exploits the mechanical and chemical effects of ultrasonication for the controlled activation of prodrugs. In polymer mechanochemistry, materials scientists exploit the sonomechanical effect of acoustic cavitation to mechanochemically activate force-sensitive prodrugs.

Synchronous Sound Recognition and Energy Harvesting by Flexible Piezoelectric PLLA/VB Composites.

In the present study, poling-free PLLA/VB piezoelectric composites are fabricated to achieve synchronous sound recognition and energy harvesting. The addition of VB can interact with PLLA by intermolecular hydrogen bonding, inducing the dipole orientation of C=O in PLLA. Meanwhile, VB can promote crystallization of PLLA through heterogeneous nucleation.

Highly Biocompatible Polyester-Based Piezoelectric Elastomer with Antitumor and Antibacterial Activity for Ultrasound-Enhanced Piezoelectric Therapy.

Currently, the use of piezoelectric materials to provide sustainable and noninvasive bioelectric stimulation to eradicate tumor cells and accelerate wound healing has raised wide attention. The development of a multifunctional piezoelectric elastomer with the ability to perform in situ tumor therapy as well as wound repair is of paramount importance. However, current piezoelectric materials have a large elastic modulus and limited stretchability, making it difficult to match with the dynamic curvature changes of the wound.

Leader humor: A double-edged sword.

Leader humor has been considered one of the most promising yet least understood influential tools by psychologists and management scholars. Here, I review the growing body of research on leader humor and its implications for followers and organizations, showing that despite being theorized as a positive leadership tool, leader humor can function as a double-edged sword in bringing both beneficial and detrimental outcomes for followers and organizations.In the process, I identify six distinct mechanisms (three positive and three negative) through which leader humor affects followers.

Hierarchical Fusion Network with Enhanced Knowledge and Contrastive Learning for Multimodal Aspect-Based Sentiment Analysis on Social Media.

Aspect-based sentiment analysis (ABSA) is a task of fine-grained sentiment analysis that aims to determine the sentiment of a given target. With the increased prevalence of smart devices and social media, diverse data modalities have become more abundant. This fuels interest in multimodal ABSA (MABSA).

Force-Triggered Atropisomerization of a Parallel Diarylethene to Its Antiparallel Diastereomers.

This paper describes a mechanical approach to inducing the atropisomerization of a parallel diarylethene into its antiparallel diastereomers exhibiting distinct chemical reactivity. A congested parallel diarylethene mechanophore in the ()-configuration with mirror symmetry is atropisomerized to its antiparallel diastereomers with symmetry under ultrasound-induced force field. The resulting stereochemistry-converted material gains symmetry-allowed reactivity toward conrotatory photocyclization.

The mediating effects of dysfunctional attitudes and moderating effect of sex between stressful life events and depressive symptoms among Chinese college students.

Stressful life events (SLEs) closely correlates with depressive symptoms. Although vulnerability-stress model suggests SLEs interacted with dysfunctional attitudes (DA) to predict depression, the mediation role of DA is poorly understood. Therefore, this study intended to investigate the mediating role of DA and the moderating role of sex between SLEs and self-reported depression.

Self-Healing Binder for High-Voltage Batteries.

Lithium-ion batteries are core components of flexible electronic devices. However, deformation types, such as impinging, bending, stretching, folding, and twisting, can cause internal cracks and, eventually, damage these batteries. The cracks separate the active particles from the conductive particles and the binder, as well as the electrode from the collector.

3D-Printed Bionic Ear for Sound Identification and Localization Based on In Situ Polling of PVDF-TrFE Film.

Bionic acoustic sensors are an indispensable part to realize interactions between humans and robotics. In this work, a PVDF-TrFE sensor array with multiple active pixels combined with a 3D-printed bionic ear model is prepared, which can accurately detect sounds with different frequencies and locate the sound source from different directions. The PVDF-TrFE sensor array can clearly identify the sound within 25 cm, and the error between the accepted sound frequency and the original input frequency is less than 0.

Incorporation of a Tethered Alcohol Enables Efficient Mechanically Triggered Release in Aprotic Environments.

Polymers that release small molecules in response to mechanical force are promising for a wide variety of applications. While offering a general platform for mechanically triggered release, previous mechanophore designs based on masked 2-furylcarbinol derivatives are limited to polar protic solvent environments for efficient release of the chemical payload. Here, we report a masked furfuryl carbonate mechanophore incorporating a tethered primary alcohol that enables efficient release of a hydroxycoumarin cargo in the absence of a protic solvent.

Harnessing the Power of Force: Development of Mechanophores for Molecular Release.

Polymers that release small molecules in response to mechanical force are promising materials for a variety of applications ranging from sensing and catalysis to targeted drug delivery. Within the rapidly growing field of polymer mechanochemistry, stress-sensitive molecules known as mechanophores are particularly attractive for enabling the release of covalently bound payloads with excellent selectivity and control. Here, we review recent progress in the development of mechanophore-based molecular release platforms and provide an optimistic, yet critical perspective on the fundamental and technological advancements that are still required for this promising research area to achieve significant impact.

5-Aryloxy substitution enables efficient mechanically triggered release from a synthetically accessible masked 2-furylcarbinol mechanophore.

Polymers that release small molecules in response to mechanical force are attractive materials for a wide variety of applications. Here, we report a new mechanophore platform based on a masked 2-furylcarbinol derivative that incorporates a 5-aryloxy group, which serves as both an electron-rich substituent to accelerate molecular release and the position of polymer attachment proximal to the furan-maleimide junction. The mechanophore is readily synthesized and efficiently releases both phenol and arylamine payloads following mechanical activation.

Mechanically Triggered Release of Functionally Diverse Molecular Payloads from Masked 2-Furylcarbinol Derivatives.

Polymers that release functional small molecules in response to mechanical force are appealing targets for drug delivery, sensing, catalysis, and many other applications. Mechanically sensitive molecules called mechanophores are uniquely suited to enable molecular release with excellent selectivity and control, but mechanophore designs capable of releasing cargo with diverse chemical functionality are limited. Here, we describe a general and highly modular mechanophore platform based on masked 2-furylcarbinol derivatives that spontaneously decompose under mild conditions upon liberation via a mechanically triggered reaction, resulting in the release of a covalently installed molecular payload.

Associations between feelings/behaviors during COVID-19 pandemic lockdown and depression/anxiety after lockdown in a sample of Chinese children and adolescents.

Background: Children and adolescents may be more susceptible to mental disorders due to COVID-19 pandemic than adults. This study aimed to identify correlated factors for depression/anxiety among children and adolescents after COVID-19 pandemic lockdown.

Methods: An online survey by cluster sampling was conducted after lockdown in 5175 Chinese children and adolescents with informed consents from their parents.

Mechanically Triggered Small Molecule Release from a Masked Furfuryl Carbonate.

Stimuli-responsive polymers that release small molecules under mechanical stress are appealing targets for applications ranging from drug delivery to sensing. Here, we describe a modular mechanophore design platform for molecular release via a mechanically triggered cascade reaction. Mechanochemical activation of a furan-maleimide Diels-Alder adduct reveals a latent furfuryl carbonate that subsequently decomposes under mild conditions to release a covalently bound cargo molecule.

Mechanochemical Regulation of a Photochemical Reaction.

We introduce the concept of mechanochemically gated photoswitching. Mechanical regulation of a photochemical reaction is exemplified using a newly designed mechanophore based on a cyclopentadiene-maleimide Diels-Alder adduct. Ultrasound-induced mechanical activation of the photochemically inert mechanophore in polymers generates a diarylethene photoswitch via a retro-[4 + 2] cycloaddition reaction that photoisomerizes between colorless and colored states upon exposure to UV and visible light.

Preparation and Properties of Novel Thermoplastic Vulcanizate Based on Bio-Based Polyester/Polylactic Acid, and Its Application in 3D Printing.

Thermoplastic vulcanizate (TPV) combines the high elasticity of elastomers and excellent processability of thermoplastics. Novel bio-based TPV based on poly (lactide) (PLA) and poly (1,4-butanediol/2,3-butanediol/succinate/itaconic acid) (PBBSI) were prepared in this research. PBBSI copolyesters were synthesized by melting polycondensation, and the molecular weights, chemical structures and compositions of the copolyesters were characterized by GPC, NMR and FTIR.

UV and NIR-Responsive Layer-by-Layer Films Containing 6-Bromo-7-hydroxycoumarin Photolabile Groups.

This paper describes polyelectrolyte multilayer films prepared by the layer-by-layer (LbL) technique capable of undergoing dissolution upon exposure to either ultraviolet or near-infrared light. Film dissolution is driven by photochemical deprotection of a random methacrylic copolymer with two types of side chains: (i) 6-bromo-7-hydroxycoumarinyl esters, photocleavable groups that are known to have substantial two-photon photolysis cross sections, and (ii) cationic residues from the commercially available monomer N,N-dimethylaminoethyl methacrylate (DMAEMA). In addition, the dependence of stability of both unirradiated and irradiated films on pH provides experimental evidence for the necessity of disrupting both ion-pairing and hydrophobic interactions between polyelectrolytes to realize film dissolution.

Self-Cleaning Membranes from Comb-Shaped Copolymers with Photoresponsive Side Groups.

In this study, we present a novel self-cleaning, photoresponsive membrane that is capable of removing predeposited foulant layers upon changes in surface morphology in response to UV or visible light irradiation while maintaining stable pore size and water permeance. These membranes were prepared by creating thin film composite (TFC) membranes by coating a porous support membrane with a thin layer of novel comb-shaped graft copolymers at two side-chain lengths featuring polyacrylonitrile (PAN) backbones and photoreactive side chains, synthesized by atom transfer radical polymerization (ATRP). Photoregulated control over membrane properties is attained through a light-induced transition, where the side chains switch between a hydrophobic spiropyran (SP) state and a zwitterionic, hydrophilic merocyanine (MC) state.

Triggered Release of Encapsulated Cargo from Photoresponsive Polyelectrolyte Nanocomplexes.

Combining the numerous advantages of using light as a stimulus, simple free radical random copolymerization, and the easy, all-aqueous preparation of polyelectrolyte complexes (PECs), we prepared photolabile PEC nanoparticles and demonstrated their rapid degradation under UV light. As a proof of concept demonstration, the dye Nile Red was encapsulated in the PECs and successfully released into the surrounding solution as the polyelectrolyte nanocomplex carriers dissolved upon light irradiation.

Stimuli-Responsive Free-Standing Layer-By-Layer Films.

Free-standing, stimuli-responsive polyelectrolyte multilayer films enabled by light-induced degradation of sacrificial compartments are introduced. Two examples are described: i) a triple responsive film that uses light, redox, and pH for different functions, and ii) different wavelengths of light for different functions. This approach to multiresponsive materials offers simple design and chemical synthesis while enabling different stimuli to perform separate functions in the same material.

Synthesis and characterization of biobased isosorbide-containing copolyesters as shape memory polymers for biomedical applications.

Novel biobased isosorbide-containing copolyesters (PBISI copolyesters) with both biocompatibility and sustainability were synthesized by using commercially available biobased diols and diacids. Due to the presence of itaconate in copolyesters, it can be readily crosslinked by peroxide into a crystallizable network. The structure and thermal properties of PBISI copolyesters were determined by H NMR, FTIR, DSC, and WAXD.

Photoresponsive gels prepared by ring-opening metathesis polymerization.

This communication describes photoresponsive gels, prepared using ring-opening metathesis polymerization (ROMP), that dissolve upon irradiation with ultraviolet light. Exposure of mixtures of norbornene-type ROMP monomers and new photoreactive cross-linkers comprising two norbornene units bound through a chain containing o-nitrobenzyl esters (NBEs) to well-known ruthenium carbene catalysts gave cross-linked polymer networks that swelled in organic solvents or water depending on the structure of the monomer. These gels became homogeneous upon irradiation with UV light, consistent with breaking of the cross-links through photolysis of the NBE groups.