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In this study, we newly synthesized four α-pyrrolidinononanophenone (α-PNP) derivatives [4'-halogenated derivatives and α-pyrrolidinodecanophenone (α-PDP)], and then performed the structure-cytotoxicity relationship analyses. The results showed the rank order for the cytotoxic effects, α-PNPα-PDP4'-fluoro-α-PNP4'-chrolo-α-PNP4'-bromo-α-PNP4'-iodo-α-PNP (I-α-PNP), and suggest that cytotoxicities of 4'-halogenated derivatives were more intensive than that of elongation of the hydrocarbon chain (α-PDP). We also surveyed the apoptotic mechanism of I-α-PNP in brain microvascular endothelial (HBME) cells that are utilized as the in vitro model of the blood-brain barrier. HBME cell treatment with I-α-PNP facilitated the apoptotic events (caspase-3 activation, externalization of phosphatidylserine, and DNA fragmentation), which were almost completely abolished by pretreating with antioxidants. In addition, the immunofluorescent staining revealed the enhanced production of hydroxyl radical in mitochondria by the I-α-PNP treatment, inferring that the I-α-PNP treatment triggers the apoptotic mechanism dependent on the enhanced ROS production in mitochondria. The treatment with I-α-PNP increased the production of cytotoxic aldehyde 4-hydroxy-2-nonenal and decreased the amount of reduced glutathione. Additionally, the treatment decreased the 26S proteasome-based proteolytic activities and aggresome formation. These results suggest that decrease in the antioxidant properties is also ascribable to HBME cell apoptosis elicited by I-α-PNP.

Massive vertical vein aneurysm in a supracardiac total anomalous pulmonary venous connection is rare. Herein, vertical vein aneurysm with total anomalous pulmonary venous connection and additional pathological findings are reported in a young child.

Skin-like intrinsically stretchable soft electronic devices are essential to realize next-generation remote and preventative medicine for advanced personal healthcare1-4. The recent development of intrinsically stretchable conductors and semiconductors has enabled highly mechanically robust and skin-conformable electronic circuits or optoelectronic devices2,5-10. However, their operating frequencies have been limited to less than 100 hertz, which is much lower than that required for many applications. Here we report intrinsically stretchable diodes-based on stretchable organic and nanomaterials-capable of operating at a frequency as high as 13.56 megahertz. This operating frequency is high enough for the wireless operation of soft sensors and electrochromic display pixels using radiofrequency identification in which the base-carrier frequency is 6.78 megahertz or 13.56 megahertz. This was achieved through a combination of rational material design and device engineering. Specifically, we developed a stretchable anode, cathode, semiconductor and current collector that can satisfy the strict requirements for high-frequency operation. Finally, we show the operational feasibility of our diode by integrating it with a stretchable sensor, electrochromic display pixel and antenna to realize a stretchable wireless tag. This work is an important step towards enabling enhanced functionalities and capabilities for skin-like wearable electronics. Agency for Science, Technology and Research (A*STAR) This work was partially supported by SAIT, Samsung Electronics Co., Ltd., and the Agency for Science, Technology and Research (A*STAR) under its Advanced Manufacturing and Engineering (AME) Programmatic Scheme (no. A18A1b0045). N.M. was partially supported by a Japan Society for the Promotion of Science (JSPS) overseas research fellowship. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under award ECCS-1542152. Experiments performed during revision were carried out in Keio University and was supported by JST, PRESTO Grant Number JPMJPR20B7, Japan.

Intrinsically stretchable electronics can form intimate interfaces with the human body, creating devices that could be used to monitor physiological signals without constraining movement. However, mechanical strain invariably leads to the degradation of the electronic properties of the devices. Here we show that strain-insensitive intrinsically stretchable transistor arrays can be created using an all-elastomer strain engineering approach, in which the patterned elastomer layers with tunable stiffnesses are incorporated into the transistor structure. By varying the cross-linking density of the elastomers, areas of increased local stiffness are introduced, reducing strain on the active regions of the devices. This approach can be readily incorporated into existing fabrication processes, and we use it to create arrays with a device density of 340 transistors cm–2 and a strain insensitivity of less than 5% performance variation when stretched to 100% strain. We also show that it can be used to fabricate strain-insensitive circuit elements, including NOR gates, ring oscillators and high-gain amplifiers for the stable monitoring of electrophysiological signals. An all-elastomer strain engineering approach, which uses patterned elastomer layers with tunable stiffnesses, can be used to create intrinsically stretchable transistor arrays with a device density of 340 transistors cm–2 and strain insensitivity of less than 5% performance variation when stretched to 100% strain.

Understanding the relationship between the molecular structure and morphological behaviors of well-defined semiconducting polymers is essential for developing novel conjugated building blocks and determining the origin of the functional characteristics of semiconducting polymers. Here, we provide insights into the significant temperature-dependent morphological transitions of novel well-defined polythiophene derivatives with m-alkoxy-substituted fluoro-aryl side units: poly(3-(4-fluoro-3-(hexyloxy)phenyl)thiophene) (PHFPT) and poly(3-(4-fluoro-3-(dodecyloxy)phenyl)thiophene) (PDFPT). We found that these unique morphological transitions depend on the alkyl chain length of the substituted fluoro-aryl side units. In PHFPT with short alkyl chains, the thermal treatment promotes a crowded interdigitated packing structure, resulting in narrow lamellar spacings in its crystalline structure. In contrast, the long alkyl chain of PDFPT acts as a physical spacer and disturbs the crowded interdigitation. In addition, the thermal treatment induces the backbone planarization and an ordered packing morphology in PDFPT. These demonstrations provide a critical milestone for the phase transitions of semiconducting polymers with conjugated side units.

Polymeric materials in nature regularly employ ordered, hierarchical structures in order to perform unique and precise functions. Importantly, these structures are often formed and stabilized by the cooperative summation of many weak interactions as opposed to the independent association of a few strong bonds. Here, we show that synthetic, flexible polymer chains with periodically placed and directional dynamic bonds collectively assemble into supramolecular nanofibers when the overall molecular weight is below the polymer's critical entanglement molecular weight. This causes bulk films of long polymer chains to have faster dynamics than films of shorter polymer chains of identical chemical composition. The formation of nanofibers increases the bulk film modulus by over an order of magnitude and delays the onset of terminal flow by more than 100 °C, while still remaining solution processable. Systematic investigation of different polymer chain architectures and dynamic bonding moieties along with coarse-grained molecular dynamics simulations illuminate governing structure-function relationships that determine a polymer's capacity to form supramolecular nanofibers. This report of the cooperative assembly of multivalent polymer chains into hierarchical, supramolecular structures contributes to our fundamental understanding of designing biomimetic functional materials.

Conjugation breakers (CBs) with different H-bonding chemistries and linker flexibilities are designed and incorporated into a diketopyrrolopyrrole (DPP)-based conjugated polymer backbone. The effects of H-bonding interactions on polymer semiconductor morphology, mechanical properties, and electrical performance are systematically investigated. We observe that CBs with an H-bonding self-association constant >0.7 or a denser packing tendency are able to induce higher polymer chain aggregation and crystallinity in as-casted thin films, resulting in a higher modulus and crack on-set strain. Additionally, the rDoC (relative degree of crystallinity) of the stretched thin film with the highest crack on-set strain only suffers a small decrease, suggesting the main energy dissipation mechanism is the breakage of H-bonding interactions. By contrast, other less stretchable polymer films dissipate strain energy through the breakage of crystalline domains, indicated by a drastic decrease in rDoC. Furthermore, we evaluate their electrical performances under mechanical strain in fully stretchable field-effect transistors. The polymer with the highest crack on-set strain has the least degradation in mobility as a function of strain. Overall, these observations suggest that we can aptly tune the mechanical properties of a polymer semiconductor by modulating intermolecular interactions, such as H-bonding chemistry and linker flexibility. Such understanding provides molecular design guidelines for future stretchable semiconductors.

Background :The occurrence of pneumonia is strongly associated with oral health in older people. The study aim was to clarify the effect of the suspension of visiting dental services on the occurrence of pneumoniaduring thecoronavirus disease 2019 (COVID-19) pandemic.Methods :A self-administered postal questionnaire survey was conducted in 215 nursing homes in Japan. The questionnaire assessed the provision of visiting dental services and the interruption of theseservices following COVID-19emergency restrictions. Pneumonia, hospitalization, and mortality rates were examinedfor January–June 2019 and January–June 2020. Results :Of facilities receiving visiting dental services, 37.7%had interruptions tothoseservices. Overall, pneumonia, hospitalization, and mortality rates were lower in 2020 compared with 2019.In those facilities with nointerruptions, rates were significantly lower in 2020 compared with 2019,whereasthere was no significant difference between 2019 and 2020 in facilities with interruptions.Conclusion :Continuous dental services in nursing homes during the COVID-19 pandemic led to lower rates of pneumonia, hospitalization, and mortality.

Shape memory polymers are promising materials in many emerging applications due to their large extensibility and excellent shape recovery. However, practical application of these polymers is limited by their poor energy densities (up to ∼1 MJ/m3). Here, we report an approach to achieve a high energy density, one-way shape memory polymer based on the formation of strain-induced supramolecular nanostructures. As polymer chains align during strain, strong directional dynamic bonds form, creating stable supramolecular nanostructures and trapping stretched chains in a highly elongated state. Upon heating, the dynamic bonds break, and stretched chains contract to their initial disordered state. This mechanism stores large amounts of entropic energy (as high as 19.6 MJ/m3 or 17.9 J/g), almost six times higher than the best previously reported shape memory polymers while maintaining near 100% shape recovery and fixity. The reported phenomenon of strain-induced supramolecular structures offers a new approach toward achieving high energy density shape memory polymers., We report an approach to achieve a high energy density shape memory polymer based on the formation of strain-induced supramolecular nanostructures, which immobilize stretched chains to store entropic energy.

As a key component in stretchable electronics, semiconducting polymers have been widely studied. However, it remains challenging to achieve stretchable semiconducting polymers with high mobility and mechanical reversibility against repeated mechanical stress. Here, we report a simple and universal strategy to realize intrinsically stretchable semiconducting polymers with controlled multi-scale ordering to address this challenge. Specifically, incorporating two types of randomly distributed co-monomer units reduces overall crystallinity and longer-range orders while maintaining short-range ordered aggregates. The resulting polymers maintain high mobility while having much improved stretchability and mechanical reversibility compared with the regular polymer structure with only one type of co-monomer units. Interestingly, the crystalline microstructures are mostly retained even under strain, which may contribute to the improved robustness of our stretchable semiconductors. The proposed molecular design concept is observed to improve the mechanical properties of various p- and n-type conjugated polymers, thus showing the general applicability of our approach. Finally, fully stretchable transistors fabricated with our newly designed stretchable semiconductors exhibit the highest and most stable mobility retention capability under repeated strains of 1,000 cycles. Our general molecular engineering strategy offers a rapid way to develop high mobility stretchable semiconducting polymers., Designing intrinsically stretchable semiconducting polymers with suitable charge transport and mechanical properties required for stretchable electronic devices remains a challenge. Here, the authors report terpolymer-based semiconductors with intrinsically high stretchability and mobility.

A novel intrinsically stretchable ABA triblock copolymer can be synthesized where A and B are poly(3-hexylthiophene) (P3HT) and polyisobutylene (PIB) segments, respectively. The deformation of the ...

Transition metal catalysts and halogens are necessary for the controlled synthesis of π-conjugated polymers; the contamination by transition-metal-based and halogen-based byproducts generally adversely affects the performance of organic devices. In this study, we demonstrate a transition-metal-free and halogen-free controlled synthesis of poly(3-alkylthienylene vinylene) (P3ATV) via Horner–Wadsworth–Emmons polycondensation. The electrophilicity of the formyl group in the AB-type monomer, (3-(2-ethylhexyl)-5-formyl-thiophene-2-ylmethyl)phosphonic acid diethyl ester, could be deactivated by resonance effect using the appropriate base (NaHMDS/15-crown-5-ether). The initiator, 5-nitro-2-thiophenecarboxaldehyde, which contains the active formyl group, readily initiated the polymerization to afford well-defined P3ATV in a chain-growth manner. The molecular weights of the polymers were controlled (1800–10 200) by the feeding monomer/initiator ratio while maintaining narrow molecular weight distributions (1.20–1.28). Furthermore, the chain extension by post-polymerization could proceed effectively, highlighting the quasi-living nature of the proposed method.

An efficient and scalable strategy to prepare libraries of discrete conjugated oligomers (Đ = 1.0) using the combination of controlled polymerization and automated flash chromatography is reported. From this two-step process, a series of discrete conjugated materials from dimers to tetradecamers could be isolated in high yield with excellent structural control. Facile and scalable access to monodisperse libraries of different conjugated oligomers opens pathways to designer mixtures with precise composition and monomer sequence, allowing exquisite control over their physical, optical, and electronic properties.

To understand the stability of oolongtheanin 3′-O-gallate (1), present in oolong tea leaves, its chemical transformation in aqueous solution was investigated under heating conditions. Four compounds were obtained from 1, which were isolated and their chemical structures were confirmed by NMR and MS. The results showed that 1 exists as an equilibrium mixture in water. Only one product was produced from the equilibrium form of 1, while the rest were produced from the other forms of 1.

Poly(3-hexylthiophene) with head-to-head/tail-to-tail regioregularity (HHTT-P3HT), controlled molecular weight and low molecular weight distribution was synthesized by Negishi catalyst-transfer polycondensation (NCTP) using tBu2Zn·2LiCl. The conditions to achieve controlled polymerizations of HHTT-P3HT were studied by optimizing the Ni catalyst, reaction concentrations and temperature. Furthermore, regioblock copolythiophenes consisting of HHTT-P3HT and P3HT segments with head-to-tail regioregularity (HT-P3HT) were synthesized by NCTP, in which the monomer addition sequence, that is, HHTT-P3HT block (1st) and HT-P3HT block (2nd), was firstly adopted. The decent yield (54–65%) of the regioblock copolythiophene was an advantageous point for the NCTP system. This decent yield was presumably derived from the carefully optimized conditions to form the quasi-living polymer of HHTT-P3HT with a stable chain end, –C–Ni(dcpe)–Br (dcpe = 1,2-bis(dicyclohexylphosphino)ethane), suited for the smooth crossover reaction and polymerization to the 2nd monomer for HT-P3HT. The obtained regioblock copolythiophene showed phase separation between the crystalline HT-P3HT domains and exclusive amorphous domains, as characterized by grazing-incidence X-ray scattering and atomic force microscopy.

The new series of ABC-type miktoarm star polymer (ABC star, A = polyisoprene (PI), B = polystyrene (PS), and C = poly(3-hexylthiophene) (P3HT)) and ABCD-type miktoarm star polymer (ABCD star, A = PI, B = PS, C = poly(α-methylstyrene) (PαMS), and D = P3HT) could be synthesized by the combination of the controlled KCTP, anionic linking reaction, and Click chemistry. By the copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition click reaction of the azido-chain-end-functional P3HT (P3HT-N3) with the alkyne-in-chain-functional AB diblock copolymer (A = PI and B = PS) (AB-alkyne) or alkyne-core-functional ABC miktoarm star polymer (A = PI, B = PS, and C = PαMS) (ABC-alkyne), the target ABC star and ABCD star, respectively, were obtained, as confirmed by size exclusion chromatography (SEC) and proton nuclear magnetic resonance (1H NMR). The thermal and optical properties of these star polymers were examined by thermal gravimetric analysis (TGA) and UV–vis spectroscopy. The dynamic scattering calorimetry (DSC), a...

Well-defined poly(2,5-dihexyloxyphenylene-1,4-diyl) (PPP) is successfully synthesized by the Negishi catalyst-transfer polycondensation (NCTP) using dilithium tetra(tert-butyl)zincate (t Bu4 ZnLi2 ). The obtained PPP possesses the number-averaged molecular weight (Mn ) values in the range of 2100-22 000 and the molar-mass dispersity (ÐM ) values in the range of 1.09-1.23. In addition, block copolymers containing PPP and poly(3-hexylthiophene) (P3HT) segments (PPP-b-P3HT) are synthesized to confirm the feasibility of chain extension between the different monomers based on NCTP.

Silver nanowires (AgNWs) are attracting much attention for their potential use in flexible or stretchable conducting film applications and in printed and wearable electronics devices. In this study, we fabricated flexible hybrid conducting films using different concentrations of composite silver ink prepared by mixing AgNW and silver nanoparticle (AgNP) materials, which we synthesized, for flexible interconnects and electrodes. These films had low resistivities at low sintering temperatures. Furthermore, they were also stable to tensile bending in comparison with a pure AgNP film. We found that there is an optimum concentration of AgNWs in the composite silver ink for the hybrid conducting film to have a lower resistivity even with sintering below 100 °C. We also found that the reason why hybrid conducting films are stable to repeated tensile bending is that AgNWs maintain functional conducting paths by making bridges that compensate for cracks between AgNPs during film bending.