Dithieno[3,2-f:2',3'-h]quinoxaline-Based Photovoltaic-Thermoelectric Dual-Functional Energy-Harvesting Wide-Bandgap Polymer and its Backbone Isomer.

Both organic solar cells (OSCs) and organic thermoelectrics (OTEs) are promising energy-harvesting technologies for future renewable and sustainable energy sources. Among various material systems, organic conjugated polymers are an emerging material class for the active layers of both OSCs and OTEs. However, organic conjugated polymers showing both OSC and OTE properties are rarely reported because of the different requirements toward the OSCs and OTEs. In this study, the first simultaneous investigation of the OSC and OTE properties of a wide-bandgap polymer PBQx-TF and its backbone isomer iso-PBQx-TF are reported. All wide-bandgap polymers form face-on orientations in a thin-film state, but PBQx-TF has more of a crystalline character than iso-PBQx-TF, originating from the backbone isomeric structures of α,α '/ß,ß '-connection between two thiophene rings. Additionally, iso-PBQx-TF shows inactive OSC and poor OTE properties, probably because of the absorption mismatch and unfavorable molecular orientations. At the same time, PBQx-TF exhibits both decent OSC and OTE performances, indicating that it satisfies the requirements for both OSCs and OTEs. This study presents the OSC and OTE dual-functional energy-harvesting wide-bandgap polymer and the future research directions for hybrid energy-harvesting materials.

Comparison of Two Electronic Physical Performance Batteries by Measurement Time and Sarcopenia Classification.

The Short Physical Performance Battery (SPPB) is a widely accepted test for measuring lower extremity function in older adults. However, there are concerns regarding the examination time required to conduct a complete SPPB consisting of three components (walking speed, chair rise, and standing balance tests) in clinical settings. We aimed to assess specific examination times for each component of the electronic Short Physical Performance Battery (eSPPB) and compare the ability of the original three-component examinations (eSPPB) and a faster, two-component examination without a balance test (electronic Quick Physical Performance Battery, eQPPB) to classify sarcopenia. The study was a retrospective, cross-sectional study which included 124 ambulatory outpatients who underwent physical performance examination at a geriatric clinic of a tertiary, academic hospital in Seoul, Korea, between December 2020 and March 2021. For eSPPB, we used a toolkit containing sensors and software (Dyphi, Daejeon, Korea) developed to measure standing balance, walking speed, and chair rise test results. Component-specific time stamps were used to log the raw data. Duration of balance examination, 5 times sit-to-stand test (5XSST), and walking speed examination were calculated. Sarcopenia was determined using the 2019 Asian Working Group for Sarcopenia (AWGS) guideline. The median age was 78 years (interquartile range, IQR: 73,82) and 77 subjects (62.1%) were female. The total mean eSPPB test time was 124.8 ± 29.0 s (balance test time 61.8 ± 12.3 s, 49.5%; gait speed test time 34.3 ± 11.9 s, 27.5%; and 5XSST time 28.7 ± 19.1 s, 23.0%). The total mean eQPPB test time was 63.0 ± 25.4 s. Based on the AWGS criteria, 34 (27.4%) patient's results were consistent with sarcopenia. C-statistics for classifying sarcopenia were 0.83 for eSPPB and 0.85 for eQPPB (p = 0.264), while eQPPB took 49.5% less measurement time compared with eSPPB. Breakdowns of eSPPB test times were identified. Omitting balance tests may reduce test time without significantly affecting the classifying ability of eSPPB for sarcopenia.

Development and Validation of 2D-LiDAR-Based Gait Analysis Instrument and Algorithm.

Acquiring gait parameters from usual walking is important to predict clinical outcomes including life expectancy, risk of fall, and neurocognitive performance in older people. We developed a novel gait analysis tool that is small, less-intrusive and is based on two-dimensional light detection and ranging (2D-LiDAR) technology. Using an object-tracking algorithm, we conducted a validation study of the spatiotemporal tracking of ankle locations of young, healthy participants (n = 4) by comparing our tool and a stereo camera with the motion capture system as a gold standard modality. We also assessed parameters including step length, step width, cadence, and gait speed. The 2D-LiDAR system showed a much better accuracy than that of a stereo camera system, where mean absolute errors were 46.2 ± 17.8 mm and 116.3 ± 69.6 mm, respectively. Gait parameters from the 2D-LiDAR system were in good agreement with those from the motion capture system (r = 0.955 for step length, r = 0.911 for cadence). Simultaneous tracking of multiple targets by the 2D-LiDAR system was also demonstrated. The novel system might be useful in space and resource constrained clinical practice for older adults.

Optical torque induces magnetism at the molecular level.

We report experimental observations of a mechanism that potentially supports and intensifies induced magnetization at optical frequencies without the intervention of spin-orbit or spin-spin interactions. Energy-resolved spectra of scattered light, recorded at moderate intensities (108 W/cm2) and short timescales (<150 fs) in a series of non-magnetic molecular liquids, reveal the signature of torque dynamics driven jointly by the electric and magnetic field components of light at the molecular level. While past experiments have recorded radiant magnetization from magneto-electric interactions of this type, no evidence has been provided to date of the inelastic librational features expected in cross-polarized light scattering spectra due to the Lorentz force acting in combination with optical magnetic torque. Here, torque is shown to account for unpolarized rotational components in the magnetic scattering spectrum under conditions that produce only polarized vibrational features in electric dipole scattering, in excellent agreement with quantum theoretical predictions.

Molecular Design Approach Managing Molecular Orbital Superposition for High Efficiency without Color Shift in Thermally Activated Delayed Fluorescent Organic Light-Emitting Diodes.

Molecular design principles of thermally activated delayed fluorescent (TADF) emitters having a high quantum efficiency and a color tuning capability was investigated by synthesizing three TADF emitters with donors at different positions of a benzonitrile acceptor. The position rendering a large overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) enhances the quantum efficiency of the TADF emitter. Regarding the orbital overlap, donor attachments at 2- and 6-positions of the benzonitrile were more beneficial than 3- and 5-substitutions. Moreover, an additional attachment of a weak donor at the 4-position further increased the quantum efficiency without decreasing the emission energy. Therefore, the molecular design strategy of substituting strong donors at the positions allowing a large molecular orbital overlap and an extra weak donor is a good approach to achieve both high quantum efficiency and a slightly increased emission energy.

Bistable Solid-State Fluorescence Switching in Photoluminescent, Infinite Coordination Polymers.

Photo-functional infinite coordinated polymers (ICPs) were synthesized that consist of the photochromic dithienylethene (DTE) and a luminescent bridging unit to give enhanced fluorescence in the solid state. We could fabricate well-ordered micropatterns of these ICPs by a soft-lithographic method, which repeatedly showed high contrast on-off fluorescence switching.

Multifunctional Acrylic Polymers with Enhanced Adhesive Property Serving as Excellent Edge Encapsulant for Stable Optoelectronic Devices.

Pendant groups in acrylic adhesive polymers (Ads) have a profound influence on adhesive and cohesive properties and additionally on encapsulant application. However, a systematic investigation to assess the impact of the pendant groups' length and bulkiness is rare, and there is not even a single report on applying Ads as interfacial adhesion promotors and encapsulation materials simultaneously. Herein, we have developed a series of multifunctional methacrylic polymers, namely, R-co-Ads, with varying pendant length and bulkiness (R = methyl (C1), ethyl (C2), propyl (C3), butyl (C4), pentyl (C5), hexyl (C6), isobutyl (iC4), and 2-ethylhexyl (2EH)). The adhesion-related experimental results reveal that R-co-Ads have high transparency, strong adhesion strength to the various contact surfaces, and a fast cure speed. In particular, C1-co-Ad shows a superior adhesion performance with an improved cross-cut index of 4B and a shear bonding strength of 1.56 MPa. We also have adopted C1-co-Ad for encapsulation of various emerging optoelectronic applications (e.g., perovskite solar cell-, charge transport-, and conductivity-related characteristics), demonstrating its excellent edge encapsulant served to improve the device stability against ambient air conditions. Our study establishes the structure-adhesion-surface relationships, advancing the better design of adhesives and encapsulants for various research fields.

Tailor-made highly luminescent and ambipolar transporting organic mixed stacked charge-transfer crystals: an isometric donor-acceptor approach.

We have rationally designed a densely packed 1:1 donor-acceptor (D-A) cocrystal system comprising two isometric distyrylbenzene- and dicyanodistyrylbenzene-based molecules, forming regular one-dimensional mixed stacks. The crystal exhibits strongly red-shifted, bright photoluminescence originating from an intermolecular charge-transfer state. The peculiar electronic situation gives rise to high and ambipolar p-/n-type field-effect mobility up to 6.7 × 10(-3) and 6.7 × 10(-2) cm(2) V(-1) s(-1), respectively, as observed in single-crystalline OFETs prepared via solvent vapor annealing process. The unique combination of favorable electric and optical properties arising from an appropriate design concept of isometric D-A cocrystal has been demonstrated as a promising candidate for next generation (opto-)electronic materials.

Combining dithieno[3,2-f:2',3'-h]quinoxaline-based terpolymer and ternary strategies enabling high-efficiency organic solar cells.

By incorporating a dithieno[3,2-f:2',3'-h]quinoxaline unit into a PM6 polymer backbone, we developed a novel terpolymer family, demonstrating composition-dependent optical, electrochemical, and morphological characteristics. Organic solar cells based on the combination of a terpolymer and ternary strategy achieved a high power conversion efficiency of 17.60%, demonstrating the validity of our combination strategy.

Conformational Locking Control of 2D Outer Side Chains via Fluorine Atom Positioning for Improving the Thermal Stability of Organic Solar Cells.

Alongside high power conversion efficiencies (PCEs), device stability, especially thermal issues, is another key factor for the successful commercialization of nonfullerene acceptor (NFA)-based organic solar cells (OSCs). Considering the significant effects of the side-chain engineering of NFAs on molecular packing and/or locking strongly associated with the thermal stability of OSCs, herein, we present two new isomeric NFAs with 4-fluoro- and 2-fluoro-substituted hexylphenyl two-dimensional (2D) outer side chains (4FY and 2FY, respectively). In contrast with the 2FY having a horizontal stretching conformation, 4FY exhibits a diagonal stretching conformation of the 2D outer side chains and a higher dipole moment, resulting in a huge difference in their crystalline/aggregation characteristics, i.e., 4FY possesses a higher crystallinity with a denser molecular packing than the 2FY neat film, as evidenced by thermal and morphological characterizations. Encouragingly, relative to the one based on 2FY, the OSC based on 4FY delivers a PCE as high as 16.4%, together with excellent thermal stability (88.4% PCE retention under 85 °C for 360 h), which is attributed to a more optimal and robust blend morphology induced by its better compatibility into the used donor component and stronger crystallinity. This work demonstrates that in addition to the improved photovoltaic property, the appropriate F-positioning on the 2D outer side chains can play a key role in controlling their conformations, which can promote the increase of the thermal stability of OSCs.

Highly fluorescent chameleon nanoparticles and polymer films: multicomponent organic systems that combine FRET and photochromic switching.

We describe the preparation of highly efficient stimulus-responsive fluorescence color-tuning in self-assembled supramolecular scaffold systems. The systems consisted of a photochromic compound (BP-BTE) in combination with unique luminescent organic materials (CN-MBE, TPS-CNMBE, TPA-2CNMBE) that exhibited intense fluorescence in the solid state. The emission spectrum was tuned by introducing fluorescence resonance energy transfer and photochromic switching capabilities into the system. The materials were used to successfully demonstrate novel fluorescence patterns that were responsive to multiple stimuli, displayed reversible fluorescence switching, and provided a nondestructive readout of the fluorescence signal.

Gryllus bimaculatus De Geer hydrolysates alleviate lipid accumulation, inflammation, and endoplasmic reticulum stress in palmitic acid-treated human hepatoma G2 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Nonalcoholic fatty liver disease (NAFLD) is one of the most common hepatic diseases closely intertwined with saturated fatty acids intake. Therefore, various studies are being conducted to find natural substances to prevent either the onset or progression of NAFLD. According to traditional medicinal literature, it has been reported that Gryllus bimaculatus De Geer (GB) has systemic detoxifying activity; however, the preventive effects of GB on NAFLD have not been elucidated to date. AIM OF STUDY: To evaluate the potential of GB as a material for the mitigation of NAFLD, we investigated the effects of GB hydrolysates on the hepatic lipid accumulation, inflammation, and endoplasmic reticulum (ER) stress in human hepatoma G2 (Hep G2) cells treated with palmitic acid (PA). METHODS: Steamed and dried GB was defatted, pulverized, and then lyophilized following hydrolyzation using Neutrase® (GB-N) or Flavourzyme® (GB-F). Hep G2 cells were incubated with GB-N or GB-F at various concentrations (0, 0.25, 0.5, and 1 mg/mL) for 24 h, and then PA was treated for another 24 h. RESULTS: The GB-N and GB-F significantly prevented the PA-induced intracellular lipid accumulation in the human liver cells (p < 0.05). Moreover, the GB-N and GB-F increased the hepatic cellular viability against the PA-treatment (p < 0.05). In addition, the GB-N and GB-F significantly ameliorated the PA-inducible proinflammatory cytokines mRNA expression, such as tumor necrosis factor-α and interleukin-1ß, compared to the PA-treated hepatic cells (p < 0.05). Furthermore, the GB-N and GB-F inhibited the PA-inducible lipogenic mRNA expression, such as fatty acid synthase, sterol regulatory element-binding protein 1c, and peroxisome proliferator-activated receptor-γ (p < 0.05). Moreover, the GB-N and GB-F alleviated the ER stress-related mRNA expression, such as glucose regulatory protein 78 and X-box binding protein increased in PA-treated cells (p < 0.05). CONCLUSIONS: These results indicate that GB-N and GB-F could be used as materials to prevent the NAFLD onset or progression with alleviating hepatic lipid accumulation, inflammation, and ER stress.

Charge Transfer as the Key Parameter Affecting the Color Purity of Thermally Activated Delayed Fluorescence Emitters.

The key factors determining the emission bandwidth of thermally activated delayed fluorescence (TADF) are investigated by combining computational and experimental approaches. To achieve high internal quantum efficiencies in a metal-free organic light-emitting diode via TADF, the first triplet (T1) to first singlet (S1) reverse intersystem crossing is promoted by configuring molecules in an electron donor-acceptor (D-A) alternation with a large dihedral angle, which results in a small energy gap (ΔEST) between S1 and T1 levels. This allows for effective non-radiative up-conversion of triplet excitons to singlet excitons that fluoresce. However, this traditional molecular design of TADF results in broad emission spectral bands (full-width at half-maximum = 70-100 nm). Despite reports suggesting that suppressing the D-A dihedral rotation narrows the emission band, the origin of emission broadening remains elusive. Indeed, our results suggest that the intrinsic TADF emission bandwidth is primarily determined by the charge transfer character of the molecule, rather than its propensity for rotational motion, which offers a renewed perspective on the rational molecular design of organic emitters exhibiting sharp emission spectra.

Comparison of Human Interpretation and a Rule-Based Algorithm for Instrumented Sit-to-Stand Test.

BACKGROUND: The five times sit-to-stand test (5STS) is one of the most commonly used tests to assess the physical performance of lower extremities. This study assessed the correlation between human interpretation (5STShuman) and a rule-based algorithm (5STSrule) using instrumented 5STS with two sensors. METHODS: We analyzed clinical records of 148 patients who visited the geriatric outpatient clinic of Asan Medical Center between December 2020 and March 2021 and underwent physical performance assessment using the electronic Short Physical Performance Battery (eSPPB) protocol. For STS, time-weight and time-distance curves were constructed using a loadcell and light detection and ranging (LiDAR). We manually assessed the grids of these curves to calculate 5STShuman, while 5STSrule used an empirical rule-based algorithm. RESULTS: In the study population, the mean 5STShuman and 5STSrule times, i.e., 12.2±0.4 and 11.4±0.4 seconds, respectively, did not differ significantly (p=0.232). Linear regression analysis showed that 5STShuman and 5STSrule were positively correlated (ß=0.99, R2=0.99). The measures also did not differ (p=0.381) in classifying sarcopenia according to the Asian Working Group Society criteria, with C-indices of 0.826 for 5STShuman and 0.820 for 5STSrule. CONCLUSION: An empirical rule-based algorithm correlated with human-interpreted 5STS and had comparable classification ability for sarcopenia.

Multistimuli two-color luminescence switching via different slip-stacking of highly fluorescent molecular sheets.

Color tuning and switching of the solid-state luminescence of organic materials are attractive subjects for both the fundamental research and practical applications such as optical recording. We report herein cyanostilbene-based highly luminescent molecular sheets which exhibit two-color fluorescence switching in response to pressure, temperature, and solvent vapor. The origin for the multistimuli luminescence switching is the two-directional shear-sliding capability of molecular sheets, which are formed via intermolecular multiple C-H···N and C-H···O hydrogen bonds. The resulting two distinctive crystal phases are promoted by different modes of local dipole coupling, which cause a substantial alternation of π-π overlap. These changes can be directly correlated with the subsequent intermolecular excitonic and excimeric coupling in both phases, as demonstrated by an in-depth theory-assisted spectroscopic and structural study. Finally, we have prepared a first device demonstrator for rewritable fluorescent optical recording media which showed multistimuli luminescence tuning with fast response. Our multistimuli responsive system is unique in terms of the slip-stacking of molecular sheets and thus provides a novel concept of rewritable fluorescent optical recording media.

Organic Light-Emitting Diode Employing Metal-Free Organic Phosphor.

Metal-free organic phosphorescent materials are promising alternatives to the organometallic counterparts predominantly adopted in organic light-emitting diodes due to their low cost, chemical stability, and large molecular design window. However, only a few reports on OLED devices incorporating metal-free organic phosphors have been presented due to the lack of understanding on material properties, device physics, and device fabrication processes. Here, we report a tailor-designed novel fluorene-based organic phosphor with efficient spin-orbit coupling activated by bromine, aromatic carbonyl, and spiro-annulated phenyl moieties. Photoluminescence quantum yield of 24.0% was achieved when doped in optically inert amorphous polymer hosts. Effects of OLED host materials on the phosphor were investigated in terms of color purity, suppression of exciplex emission, and restraint of molecular motion. Bright green phosphorescence emission (1430 cd/m2 at 100 mA/cm2) was realized with 2.5% maximum external quantum efficiency at 1 mA/cm2.

Functional Age Predicted by Electronic Short Physical Performance Battery Can Detect Frailty Status in Older Adults.

PURPOSE: The importance of evaluating frailty status of older adults in clinical practice has been gaining attention with cumulative evidence showing its relevance in clinical outcomes and decision-making. We aimed to develop and validate whether the functional age predicted by an electronic continuous short physical performance battery (eSPPB) could predict frailty status. PATIENTS AND METHODS: We reviewed medical records of outpatients (N=834) of Asan Medical Center, aged 51-95 years. We used the eSPPB data of 717 patients as a development cohort, and that of 117 patients, who also underwent comprehensive geriatric assessments, as a validation cohort. Frailty index was calculated by counting deficits of 45 geriatric items including comorbidities, daily functions, mobility, mood, and cognition. For functional age, we used balance score (0-4), gait speed (m/s), and stand-up time (s) measured 5 times in the chair rise test. RESULTS: From the development cohort, we established a functional age using the formula (83.61 - 1.98*[balance score] - 5.21*[gait speed] + 0.23*[stand-up time]), by multivariate linear regression analysis with chronological age as a dependent variable (R2 = 0.233). In the validation cohort, the functional age positively correlated with frailty index (p < 0.001). C-statistics classifying frailty (defined as frailty index ≥0.25) was higher (p < 0.001) with functional age (0.912) than that with chronological age (0.637). A cut-off functional age of ≥77.2 years maximized Youden's J when screening for frailty, with sensitivity of 94.4% and specificity of 80.8%. CONCLUSION: A newly developed functional age predictor using eSPPB parameters can predict the frailty status as defined by the deficit accumulation method and may serve as a physical biomarker of human aging.

Shear- and UV-induced fluorescence switching in stilbenic pi-dimer crystals powered by reversible [2 + 2] cycloaddition.

We have designed and synthesized asymmetric cyano-stilbene derivatives containing trifluoromethyl (-CF(3)) substituents with the aim of producing tightly packed pi-dimer systems that as crystals exhibit reversible [2 + 2] cycloaddition with characteristic fluorescence modulation. (Z)-3-(3',5'-Bis(trifluoromethyl)biphenyl-4-yl)-2-(4'-(trifluoromethyl)biphenyl-4-yl)acrylonitrile (CN(L)-TrFMBE) and its derivatives were found to form antiparallel pi-dimer stacks in crystals due to their specific intermolecular interactions, including C-F...H and C-F...pi interactions. The CN(L)-TrFMBE pi-dimer crystals (and powder) are not at all fluorescent initially but switch to a highly fluorescent state (Phi(PL) = 24%) when an external shear-strain and/or prolonged UV (365 nm) irradiation is applied. Our experimental and theoretical investigations show that the fluorescence modulation in this particular system is due to the external and/or internal (in the case of UV irradiation) shear-induced lateral displacement of the pi-dimer molecular pair, which effectively turns the fluorescence emission on at the cost of frustrated [2 + 2] cycloaddition. Further, the fluorescence 'off' state can be restored by thermal annealing, which regenerates the tightly packed pi-dimer by reverse displacement together with the thermal dissociation of the [2 + 2] cycloaddition product. This system provides a very rare example of high-contrast reversible fluorescence switching that is driven by a change in the molecular packing mode in the solid state, which enables piezochromic and photochromic responses.

Telomerase and apoptosis in the placental trophoblasts of growth discordant twins.

In an effort to investigate the molecular basis of growth discordance in embryos that experience the same uterine environment, we compared telomerase activity and apoptosis in placental trophoblasts obtained from growth discordant twins. Between January 2003 and February 2005, placental tissue from twenty pairs of twins was obtained within thirty minutes of delivery. Eleven cases were classified as growth discordant, with birth weight discordance greater than 20%. Nine cases comprised the control group, with less than 20% discordance. Telomerase and apoptotic activities in placental trophoblasts were analyzed by ELISA and immunoblot. Statistical significance was analyzed by a paired t-test, chi- squared test, and ANOVA (SPSS ver 11.0). The average growth discordance was 26.8% in the growth discordant group and 14.4% in the control group. There were no significant differences in maternal age, week of gestation at delivery, parity, or chorionisity between the two groups. In the growth discordant group, the larger twin showed significantly higher telomerase activity (p < 0.01), whereas no significant difference was observed in the control group (p = 0.36). In addition, there was no definitive correlation between telomerase activity and the degree of growth discordance in the larger or smaller twins (R = -0.521 and -0.399, p = 0.15 and 0.25, respectively). The apoptosis proteins Bax and Bcl 2 were detected in both the larger and smaller twins in the growth discordant and control groups. There was no statistically significant difference in Bax expression between the larger and smaller twins (p = 0.25 and 0.92, respectively) for either the growth discordant or the control groups. Bcl 2 expression also showed no significant difference between groups. In conclusion, a tendency toward reduced telomerase activity and increased apoptosis was discovered in placental trophoblasts of the smaller growth- discordant twin, possibility resulting in delayed fetal growh.