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Objective: To evaluate the effect of a self‐retaining block‐type bone substitute (srBB) on the dimensional stability of the horizontal ridge width at the coronal level in a buccal dehiscence model. Materials and Methods: Four box‐shaped bone defects with a buccal dehiscence were surgically prepared in the partially edentulous mandible (n = 6). Experimental biomaterials were randomly assigned to each site: (1) Control group: no treatment, (2) particle‐type bone substitute (PBS) group, (3) collagenated soft block bone substitute (csBB) group, and (4) self‐retaining synthetic block bone (srBB) group. In all grafted groups, a collagen membrane covered the biomaterials. At 16 weeks, clinical, histological, and radiographic analyses were performed. Results: Three of the six blocks in the srBB group became exposed and fell out during the first week after surgery. Therefore, the remaining three specimens were renamed RsrBB group. The RsrBB group showed an increase horizontal ridge compared to the pristine bone width at 2–4 mm below the CEJ, while the other groups showed resorption (augmented width at 2 mm below: 4.2, 42.4, 36.2, and 110.1% in the control, PBS, csBB, and RsrBB groups, respectively). The mineralized bone area was largest in the RsrBB group (4.74, 3.44, 5.67, and 7.77 mm2 in the control, PBS, csBB, and RsrBB groups, respectively.). Conclusions: The srBB group demonstrated the highest volume stability at the coronal level. These findings would potentially suggest that self‐retaining block bone substitute might be a good candidate for alveolar ridge preservation. [ABSTRACT FROM AUTHOR]

This study developed an advanced 850 nm centered distributed Bragg reflector (DBR) (broadband DBR) composed of nanomaterial-based multiple structures to improve the optical efficiency of an 850 nm near-infrared light-emitting diode (NIR-LED). A combined 850 nm centered broadband DBR was fabricated by growing an 800 nm centered ten-pair DBR on a 900 nm centered ten-pair DBR (denoted as a combined DBR). The combined DBR exhibited a slightly wider peak band than conventional DBRs. Furthermore, the peak band width of the combined DBR significantly increased upon using a reflective AlAs buffer layer that reduced the overlapped reflection. The output power (20.5 mW) of NIR-LED chips using the combined DBR with an AlAs buffer layer exceeded that of a conventional 850 nm centered DBR (14.5 mW) by more than 40%. Results indicated that combining the optical conditions of wavelengths and the AlAs buffer layer effectively strengthened the broadband effect of the DBR and increased the optical efficiency of the 850 nm NIR-LED. [ABSTRACT FROM AUTHOR]

All‐polymer photovoltaics (all‐PPVs) that operate under both indoor and outdoor lighting conditions require active layers with appropriately adjusted optical‐absorption ranges. However, the optical absorption of a conventional donor–acceptor binary blend is restricted to the combined absorption bands of its components. Herein, a new conjugated block copolymer (CBC) acceptor, b‐PYT, is designed by integrating polymer acceptor blocks of wide and narrow bandgaps in a single structure. Such combination results in the wide absorption range (550–850 nm) of b‐PYT that matches the emission of both artificial and solar light. The b‐PYT CBC acceptor is more crystalline than the corresponding random terpolymer, r‐PYT, owing to improved interactions between its macromolecular acceptor units. Despite exhibiting slightly inferior outdoor performance compared to that of devices using the homopolymer BTTP‐T, the PM6:b‐PYT‐based devices deliver superior power conversion efficiency (PCE) under indoor light‐emitting diode (LED) light owing to better matched absorption and emission spectra of b‐PYT and a cold white LED, respectively. Additionally, it is worth highlighting that PM6:b‐PYT‐based all‐PPVs can maintain approximately 87% of the initial PCE even after 600 min of thermal aging at 150 °C, which demonstrates the superior thermal stability compared with those of all‐PPVs that use traditional binary active layers. [ABSTRACT FROM AUTHOR]

BackgroundTo motivate people to adopt medical chatbots, the establishment of a specialized medical knowledge database that fits their personal interests is of great importance in developing a chatbot for perinatal care, particularly with the help of health professionals. ObjectiveThe objectives of this study are to develop and evaluate a user-friendly question-and-answer (Q&A) knowledge database–based chatbot (Dr. Joy) for perinatal women’s and their partners’ obstetric and mental health care by applying a text-mining technique and implementing contextual usability testing (UT), respectively, thus determining whether this medical chatbot built on mobile instant messenger (KakaoTalk) can provide its male and female users with good user experience. MethodsTwo men aged 38 and 40 years and 13 women aged 27 to 43 years in pregnancy preparation or different pregnancy stages were enrolled. All participants completed the 7-day-long UT, during which they were given the daily tasks of asking Dr. Joy at least 3 questions at any time and place and then giving the chatbot either positive or negative feedback with emoji, using at least one feature of the chatbot, and finally, sending a facilitator all screenshots for the history of the day’s use via KakaoTalk before midnight. One day after the UT completion, all participants were asked to fill out a questionnaire on the evaluation of usability, perceived benefits and risks, intention to seek and share health information on the chatbot, and strengths and weaknesses of its use, as well as demographic characteristics. ResultsDespite the relatively higher score of ease of learning (EOL), the results of the Spearman correlation indicated that EOL was not significantly associated with usefulness (ρ=0.26; P=.36), ease of use (ρ=0.19; P=.51), satisfaction (ρ=0.21; P=.46), or total usability scores (ρ=0.32; P=.24). Unlike EOL, all 3 subfactors and the total usability had significant positive associations with each other (all ρ>0.80; P

BackgroundAs an evidence-based psychotherapy for treating insomnia, cognitive behavioral therapy for insomnia (CBT-I), which helps people with sleep problems to change their unhelpful sleep-related beliefs and habits, has been well-established in older adults. Recently, the utilization of mobile CBT-I apps has been getting attention from mental health professionals and researchers; however, whether mobile CBT-I apps are usable among older users has yet to be determined. ObjectiveThe aims of this study were to explore the relationships between subjective sleep quality and subjective memory complaints and depressive symptoms; to explore the relationship between perceived difficulty in mobile app use and usability of the mobile phone–based self-help CBT-I app, named MIND MORE, in urban community-dwelling Korean older adults; to compare changes in subjective sleep quality from pre-intervention to post-intervention, during which they used the mobile app over a 1-week intervention period; and evaluate adherence to the app. MethodsDuring the 2-hour training program delivered on 1 day titled “Overcoming insomnia without medication: How to use the ‘MIND MORE’ mobile app for systematic self-management of insomnia” (pre-intervention), 41 attendants were asked to gain hands-on experience with the app facilitated by therapists and volunteer workers. They were then asked to complete questionnaires on sociodemographic characteristics, subjective evaluation of mental health status (ie, depression, memory loss and impairment, and sleep problems), and app usability. For the 1-week home-based self-help CBT-I using the app (post-intervention), 9 of the 41 program attendants, who had already signed up for the pre-intervention, were guided to complete the given questionnaires on subjective evaluation of sleep quality after the 1-week intervention, specifically 8 days after the training program ended. ResultsDue to missing data, 40 of 41 attendants were included in the data analysis. The main findings of this study were as follows. First, poor subjective sleep quality was associated with higher ratings of depressive symptoms (40/40; ρ=.60, P