Interfacial Mechanophore Activation Using Laser-Induced Stress Waves

A new methodology is developed to activate and characterize mechanochemical transformations at a solid interface. Maleimide–anthracene mechanophores covalently anchored at a fused silica–polymer interface are activated using laser-induced stress waves. Spallation-induced mechanophore activation is observed above a threshold activation stress of 149 MPa. The retro [4+2] cycloaddition reaction is confirmed by fluorescence microscopy, XPS, and ToF-SIMS measurements. Control experiments with specimens in which the mechanophore is not covalently attached to the polymer layer exhibit no activation. In contrast to activation in solution or bulk polymers, whereby a proportional increase in mechanophore activity is observed with applied stress, interfacial activation occurs collectively with spallation of the polymer film

A One-Step Strategy for End-Functionalized Donor–Acceptor Conjugated Polymers

A modular and robust method for preparing end-functionalized donor–acceptor (D–A) narrow bandgap conjugated polymers is reported that avoids multistep reactions and postpolymerization modification. The strategy is well-controlled and affords functional materials with predictable molecular weight and high end-group fidelity. To exemplify this synthetic strategy, narrow bandgap conjugated polymers based on PDPP2FT were prepared that contain perylene diimide (PDI) units at the chain-ends. Monte Carlo simulations confirm the high degree of chain-end functionalization while photoluminescence studies reveal the unique photophysical properties of the end-functional polymers with efficient charge transfer occurring between the main polymer chain and PDI end-groups that results exclusively from their covalent linkage

Spatially Selective and Density-Controlled Activation of Interfacial Mechanophores

Mechanically sensitive molecules known as mechanophores have recently attracted much interest due to the need for mechanoresponsive materials. Maleimide–anthracene mechanophores located at the interface between poly(glycidyl methacrylate) (PGMA) polymer brushes and Si wafer surfaces were activated locally using atomic force microscopy (AFM) probes to deliver mechanical stimulation. Each individual maleimide–anthracene mechanophore exhibits binary behavior: undergoing a retro-[4 + 2] cycloaddition reaction under high load to form a surface-bound anthracene moiety and free PGMA or remaining unchanged if the load falls below the activation threshold. In the context of nanolithography, this behavior allows the high spatial selectivity required for the design and production of complex and hierarchical patterns with nanometer precision. The high spatial precision and control reported in this work brings us closer to molecular level programming of surface chemistry, with promising applications such as 3D nanoprinting, production of coatings, and composite materials that require nanopatterning or texture control as well as nanodevices and sensors for measuring mechanical stress and damage in situ

Absorbent article having a window with a body-conforming acquisition element positioned therein

An absorbent article, such as a sanitary napkin is provided. The sanitary napkin of the present invention has at least one component facing the body surface of the sanitary napkin having a window cut out therein. The sanitary napkin is provided with an acquisition/distribution component such as a tow of resilient fibers having intra-fiber capillary channels. The tow of resilient fibers is positioned so that it at least partially lies in the space defined by the window. The acquisition/distribution component has a compressed configuration and an uncompressed configuration. In its uncompressed configuration, the acquisition/distribution component lies relatively flat behind the window. In its compressed configuration, the acquisition/distribution component forms a hump on the body surface that protrudes from the window

Recipient mucosal-associated invariant T cells control GVHD within the colon

Mucosal-associated invariant T (MAIT) cells are a unique innate-like T cell subset that responds to a wide array of bacteria and yeast through recognition of riboflavin metabolites presented by the MHC class I–like molecule MR1. Here, we demonstrate using MR1 tetramers that recipient MAIT cells are present in small but definable numbers in graft-versus-host disease (GVHD) target organs and protect from acute GVHD in the colon following bone marrow transplantation (BMT). Consistent with their preferential juxtaposition to microbial signals in the colon, recipient MAIT cells generate large amounts of IL-17A, promote gastrointestinal tract integrity, and limit the donor alloantigen presentation that in turn drives donor Th1 and Th17 expansion specifically in the colon after BMT. Allogeneic BMT recipients deficient in IL-17A also develop accelerated GVHD, suggesting MAIT cells likely regulate GVHD, at least in part, by the generation of this cytokine. Indeed, analysis of stool microbiota and colon tissue from IL-17A–/– and MR1–/– mice identified analogous shifts in microbiome operational taxonomic units (OTU) and mediators of barrier integrity that appear to represent pathways controlled by similar, IL-17A–dependent mechanisms. Thus, MAIT cells act to control barrier function to attenuate pathogenic T cell responses in the colon and, given their very high frequency in humans, likely represent an important population in clinical BMT

Initial efficacy of MI, TTM tailoring and HRI’s with multiple behaviors for employee health promotion

Objective: This study was designed to compare the initial efficacy of Motivational Interviewing (MI), Online Transtheoretical Model (TTM)-tailored communications and a brief Health Risk Intervention (HRI) on four health risk factors (inactivity, BMI, stress and smoking) in a worksite sample. Method: A randomized clinical trial assigned employees to one of three recruitment strategies and one of the three treatments. The treatment protocol included an HRI session for everyone and in addition either a recommended three TTM online sessions or three MI in person or telephone sessions over 6 months. At the initial post-treatment assessment at 6 months, groups were compared on the percentage who had progressed from at risk to taking effective action on each of the four risks. Results: Compared to the HRI only group, the MI and TTM groups had significantly more participants in the Action stage for exercise and effective stress management and significantly fewer risk behaviors at 6 months. MI and TTM group outcomes were not different. Conclusion: This was the first study to demonstrate that MI and online TTM could produce significant multiple behavior changes. Future research will examine the long-term impacts of each treatment, their cost effectiveness, effects on productivity and quality of life and process variables mediating outcomes

Interfacial Mechanophore Activation Using Laser-Induced Stress Waves

A new methodology is developed to activate and characterize mechanochemical transformations at a solid interface. Maleimide–anthracene mechanophores covalently anchored at a fused silica–polymer interface are activated using laser-induced stress waves. Spallation-induced mechanophore activation is observed above a threshold activation stress of 149 MPa. The retro [4+2] cycloaddition reaction is confirmed by fluorescence microscopy, XPS, and ToF-SIMS measurements. Control experiments with specimens in which the mechanophore is not covalently attached to the polymer layer exhibit no activation. In contrast to activation in solution or bulk polymers, whereby a proportional increase in mechanophore activity is observed with applied stress, interfacial activation occurs collectively with spallation of the polymer film

A One-Step Strategy for End-Functionalized Donor–Acceptor Conjugated Polymers

A modular and robust method for preparing end-functionalized donor–acceptor (D–A) narrow bandgap conjugated polymers is reported that avoids multistep reactions and postpolymerization modification. The strategy is well-controlled and affords functional materials with predictable molecular weight and high end-group fidelity. To exemplify this synthetic strategy, narrow bandgap conjugated polymers based on PDPP2FT were prepared that contain perylene diimide (PDI) units at the chain-ends. Monte Carlo simulations confirm the high degree of chain-end functionalization while photoluminescence studies reveal the unique photophysical properties of the end-functional polymers with efficient charge transfer occurring between the main polymer chain and PDI end-groups that results exclusively from their covalent linkage

Spatially Selective and Density-Controlled Activation of Interfacial Mechanophores

Mechanically sensitive molecules known as mechanophores have recently attracted much interest due to the need for mechanoresponsive materials. Maleimide–anthracene mechanophores located at the interface between poly(glycidyl methacrylate) (PGMA) polymer brushes and Si wafer surfaces were activated locally using atomic force microscopy (AFM) probes to deliver mechanical stimulation. Each individual maleimide–anthracene mechanophore exhibits binary behavior: undergoing a retro-[4 + 2] cycloaddition reaction under high load to form a surface-bound anthracene moiety and free PGMA or remaining unchanged if the load falls below the activation threshold. In the context of nanolithography, this behavior allows the high spatial selectivity required for the design and production of complex and hierarchical patterns with nanometer precision. The high spatial precision and control reported in this work brings us closer to molecular level programming of surface chemistry, with promising applications such as 3D nanoprinting, production of coatings, and composite materials that require nanopatterning or texture control as well as nanodevices and sensors for measuring mechanical stress and damage in situ