Highly reproducible organic field-effect transistor from pseudo 3-dimensional triphenylamine-based amorphous conjugated copolymer

An easily accessible 3D donor-acceptor polymer based on triphenylamine (PTPA-co-DTDPP) is synthesized by a simple and efficient route. Owing to its non-fibrillar structure, PTPA-co-DTDPP features highly reproducible charge carrier mobility of up to 3.3 x 10(-3) cm(2) V(-1) s(-1) at various fabrication conditions.close181

A synthetic approach to a fullerene-rich dendron and its linear polymer via ring-opening metathesis polymerization

Through the esterification of an acyl chloride functionalized fullerene precursor with dendritic alcohol, a fullerene-rich dendron containing a norbornene unit at the focal point is prepared for ring-opening metathesis polymerization to obtain its linear polymer with a unimodal and narrow molar mass distribution (PDI = 1.08) by a progressive addition of catalysts.close181

Swapping field-effect transistor characteristics in polymeric diketopyrrolopyrrole semiconductors: Debut of an electron dominant transporting polymer

A fact-finding study on thiophenyl diketopyrrolopyrrole (TDPP)-containing polymers for electronically convertible transport characteristics in organic field effect transistors (OFETs) is presented. In the subject of this consideration, a TDPP-based polymer with bis-benzothiadiazole (BisBT) units that serve as powerful electron-deficient building blocks, namely PDTDPP-BisBT, is prepared in order to achieve an n-channel transistor. The resulting polymer shows n-channel dominant ambipolar OFET characteristics and its electron mobility (1.3 x 10(-3) cm(2) V(-1) s(-1)) is found to be one order of magnitude higher than the hole mobility. Besides, the PDTDPP-BisBT OFET performance is independent of film-deposition conditions due to its completely amorphous microstructure, supported by the atomic force microscopy (AFM) and X-ray diffraction (XRD) analyses. Herein, we report an intriguing discovery in sync with our previous studies that TDPP-based polymers can function as a p-type, n-type, or ambipolar organic semiconductor in accordance with the degree of electron affinity of the comonomers.close211

Synthesis of fluorinated analogues of a practical polymer TQ for improved open-circuit voltages in polymer solar cells

In an attempt to further lower the HOMO of a cost-effective polymer poly(2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-dyl-alt-thiophene-2,5-diyl) (TQ) by adding F atoms onto the existing quinoxaline acceptor within the polymer backbone, we have synthesized two structurally identical fluorinated analogues of TQ (TQ-F (single F) and TQ-FF (double F)), except for the number of F atoms. The effects of inclusion of F atoms on the optical property, nature of charge transport, and molecular organization are thoroughly investigated. The resulting two fluorinated polymers show a decrease in both the HOMO and the LUMO energy levels relative to non-fluorinated TQ. Moreover, the fluorination of the polymer backbone has lowered the HOMOs more than the LUMOs, slightly widening the energy bandgaps as the number of F atoms increases. Thus, use of these polymers in bulk-heterojunction (BHJ) solar cells, in all cases, leads large VOC values. The power conversion efficiency (PCE) of the optimized PSCs based on TQ-F reaches 4.41%. In addition, it is interesting to note that, despite TQ-FF having the PCE that is lower than TQ-F, an unprecedentedly high VOC of 1.00 V is achieved, which is nearly equaled the highest VOC values ever reported for polymers.close4

Acceptor-acceptor type isoindigo-based copolymers for high-performance n-channel field-effect transistors

Two acceptor-acceptor (A-A) type copolymers (PIIG-BT and PIIGTPD) with backbones composed exclusively of electron-deficient units are designed and synthesized. Both copolymers show unipolar n-type operations. In particular, PIIG-BT shows electron mobility of up to 0.22 cm2 V1 s1. This is a record value for n-type copolymers based on lactam cores.close3

Two nights of recovery sleep restores hippocampal connectivity but not episodic memory after total sleep deprivation

Sleep deprivation significantly impairs a range of cognitive and brain function, particularly episodic memory and the underlying hippocampal function. However, it remains controversial whether one or two nights of recovery sleep following sleep deprivation fully restores brain and cognitive function. In this study, we used functional magnetic resonance imaging (fMRI) and examined the effects of two consecutive nights (20-hour time-in-bed) of recovery sleep on resting-state hippocampal connectivity and episodic memory deficits following one night of total sleep deprivation (TSD) in 39 healthy adults in a controlled in-laboratory protocol. TSD significantly reduced memory performance in a scene recognition task, impaired hippocampal connectivity to multiple prefrontal and default mode network regions, and disrupted the relationships between memory performance and hippocampal connectivity. Following TSD, two nights of recovery sleep restored hippocampal connectivity to baseline levels, but did not fully restore memory performance nor its associations with hippocampal connectivity. These findings suggest that more than two nights of recovery sleep are needed to fully restore memory function and hippocampal-memory associations after one night of total sleep loss

Association between physical activity and metabolic syndrome in middle-aged Japanese: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Although many studies have reported an association between self-reported physical activity and metabolic syndrome (MetS), there is limited information on the optimal level of physical activity required to prevent MetS. This study aimed to determine the association between objectively measured physical activity and MetS in middle-aged Japanese individuals. We also determined the optimal cutoff value for physical activity required to decrease the risk of developing MetS.</p> <p>Methods</p> <p>A total of 179 men and 304 women, aged between 30 and 64 years, participated in this study. Participants were divided into two groups using the Japanese criteria for MetS as those with MetS or pre-MetS, and those without MetS. Participants were considered to be physically active if they achieved a physical activity level of 23 metabolic equivalents (METs) h/week, measured using a triaxial accelerometer. The association between physical activity and MetS was analyzed using logistic regression with the following covariates: sex, age, sedentary time, low intensity activity, calorie intake, smoking, menopause and body mass index. We also evaluated the factors that determined the association between the prevalence of MetS and pre-MetS and the physical activity cutoff value using classification and regression tree (CART) analysis.</p> <p>Results</p> <p>The odds ratio for MetS and pre-MetS was 2.20 for physically inactive participants (< 23 METs h/week), compared with physically active participants (≥ 23 METs h/week). The corresponding odds ratios for men and women were 2.27 (<it>P </it>< 0.01) and 1.95 (not significant), respectively. CART analyses revealed that moderate-vigorous physical activity of > 26.5 METs h/week was sufficient to decrease the prevalence of MetS and pre-MetS in middle-aged Japanese men and women.</p> <p>Conclusions</p> <p>The results of this cross-sectional study indicate that the Exercise and Physical Activity Reference for Health Promotion 2006 is inversely associated with the prevalence of MetS in men. Our results also suggest that moderate physical activity of > 26.5 METs h/week may decrease the risk of developing MetS and pre-MetS in middle-aged Japanese individuals.</p

Homosexuals and the Contemporary Gay Rights Movement in Korea: Movement participation and collective identity

This study examines how elements of collective identification are reflected in Korean male homosexuals and how it impacts on their engagement with the gay rights movement. Quantitative research was conducted regarding the elements of collective identification of Korean male homosexuals and the outcome of participating in collective action for gay rights. The first part (chapter 1, 2, 3) of this study is the basis for the development of this collective identification research. A set of research questions are introduced along with an examination of two dominant literatures on the subject: collective identity theories and social movement theories. These have been pursued to generate a theoretical framework for collective identification in terms of the gay rights movement. Further, the situation of homosexuals and gay rights in contemporary Korea is analyzed. The second part (chapter 4, 5, 6, 7) discusses the methodology, conduct of the quantitative research and the findings. A correlation is discovered between elements of collective identification and their relation to an outcome (collective action participation). Elements of collective identification analyzed in this research are self-categorization, private regard, social embeddedness, interdependence and ideology (belief in gay visibility, belief in collective action and recognition on social oppression). Finally, the research confirms the unique motivating influence of a number of collective identity elements. Some of recommendations are made for promoting the gay rights movement in Korea. The research could potentially help Korean gay rights activists who are facing the difficulty of encouraging individual homosexuals to participate in collective action for gay rights

A Smart City Service Business Model: Focusing on Transportation Services

Most cities have adopted smart city services to solve urban problems. However, an examination of their operations reveals that many of these services have either been discontinued or have failed to advance further since they were not profitable. Therefore, this study reviews and proposes the business models of smart city services at a fundamental level. It defines and classifies the smart city service focusing on transportation and the components. The business model has been constructed for electric vehicles and autonomous shuttle businesses in terms of transportation services. It found that the model was profitable in each business only when various stakeholders were linked for mutual interests. Since various service stakeholders cooperate in smart city service, if one of them is unable to secure profitability, it is difficult to operate the smart city service fully. Therefore, a detailed review of the business model is required before providing a smart city service