It is important to fabricate nanostructured architectures comprised of functional components for a wide variety of applications because precise structural control in the nanometer regime can yield unprecedented, fascinating properties. Owing to their well-defined microstructural characteristics, it has been popular to use carbon nanospecies, such as nanotubes and graphene, in fabricating nanocomposites and nanohybrids. Nevertheless, it still remains hard to control and manipulate nanospecies for specific applications, thus preventing their commercialization. Herein, first, we report unique one-dimensional nanoarchitectures with meso-/macropores, consisting of single-walled nanotubes (SWNTs), graphene, and polyacrylonitrile, in which poly(vinyl alcohol) was employed as a dispersing agent and sacrificial porogen. One-dimensional SWNTs and two-dimensional graphene pieces were combined in the confined interior space of electrospun nanofibers, which led to unique microstructural characteristics such as enhanced ordering of SWNTs, graphene pieces, and polymer chains in the nanofiber interior. Next, the SWNT/graphene-in-polymer nanofiber (SGPNF) structures were converted into carbonized products (SGCNFs) with effective porosity and tunable electrochemical properties. Similar to SGPNFs, the microstructural and electrical properties of the SGCNFs depended on the incorporated amount of SWNT and graphene. At higher SWNT content, the mesopore volume proportion and specific discharge capacitance of the SGCNFs increased by max. 63 and 598%, respectively. The SGCNFs showed strong potential as a high-performance electrode material for electrochemical capacitors (max. capacitance: nonactivated ∼390 F g-1 and activated ∼750 F g-1). Flexible, all solid-state capacitor cells based on SGCNFs were also successfully demonstrated as a model application. The SGCNFs can be further functionalized by various methods, which will impart attractive properties for extended applications.
Abstract Insulating polymers have received little attention in electronic applications. Here, we synthesize a photoresponsive, amphiphilic block copolymer (PEO- b -PVBO) and further control the chain growth of the block segment (PVBO) to obtain different degrees of polymerization (DPs). The benzylidene oxazolone moiety in PEO- b -PVBO facilitated chain-conformational changes due to photoisomerization under visible/ultraviolet (UV) light illumination. Intercalation of the photoresponsive but electrically insulating PEO- b -PVBO into graphene sheets enabled electrical monitoring of the conformational change of the block copolymer at the molecular level. The current change at the microampere level was proportional to the DP of PVBO, demonstrating that the PEO- b -PVBO-intercalated graphene nanohybrid (PGNH) can be used in UV sensors. Additionally, discrete signals at the nanoampere level were separated from the first derivative of the time-dependent current using the fast Fourier transform (FFT). Analysis of the harmonic frequencies using the FFT revealed that the PGNH afforded sawtooth-type current flow mediated by Coulomb blockade oscillation.
We conduct a field experiment to investigate the elects of partisan news on the 2016 Taiwan Presidential and Legislative Elections. Sub- jects are divided into four groups: rightist (KMT), leftist (DPP), new third-party and control, and provided with distinct partisan news ar- ticles. To ensure readership of assigned newspapers, subjects join multiple experimental sessions in which they are asked to solve quiz questions about the news articles and rewarded according to their quiz scores. We measure the elects of partisan news by comparing the reported vote choices in the 2016 Elections with subjects' initial political preferences. We find that the leftist news articles have signif- icantly increased the support for the DPP candidate Tsai by reinforc- ing the existing preferences. The articles about the third-parties have changed subjects' voting intentions to support the new party GSD. We also find that the estimated baseline and reinforcement treatment elects are driven by undecided subjects or swing voters.
최근 프로 스포츠에서는 데이터를 활용하는 분야가 주목을 받기 시작하였다. 데이터 활용 분야는 경기 내적으로 파생되는 클래식 기록 뿐만 아니라, 효율성을 강조한 2차 기록도 적극적으로 활용되고 있다. 이에 본 연구에 서는 경기 외적인 데이터인 일일 평균 습도를 통하여 투수들의 탈삼진 능력과의 상관관계를 연구하고자 한다. 이를 위 하여 KBO리그에 소속된 10개 팀의 홈구장과 보조구장에 소재한 지역의 일일 평균 기록을 참고로 하였고, 선발 투수 와 구원 투수들의 특성을 파악하기 위하여 다승, 홀드, 세이브 부문의 상위 5명 씩의 K/9기록을 대상으로 분석하였 다. 본 연구결과를 통하여 선발 투수와 구원 투수와의 K/9 기록에 유의미한 차이를 발견하였으며, 프로 스포츠의 데이터 활용에 대하여 학문 및 산업 전반의 발전을 기대할 수 있다.
Abstract Combining the characteristics of different materials offers exciting new opportunities for advanced applications in various fields. Herein, white light‐emitting diodes (WLEDs) with >200% reversible stretchability are fabricated using six‐color quantum dots (QDs) gel emitters. Stable aqueous‐phase alloy core/shell QDs with high quantum yield are obtained via ligand exchange using a ternary solvent system. Transparent and highly stretchable gels with large pores are created by binary‐solvent‐based gelation at low temperatures. Importantly, the QDs and the gel originate from the same two solvents, which make the QDs highly compatible with the gelation process. Consequently, QDs of six different colors are incorporated into the gel without any property degradation. The excellent optical properties of the QDs in the liquid phase (e.g., 17% higher photoluminescence (PL) intensity) are retained in the gel phase. The QD gel (QDG) exhibits elastic deformation up to 200%, with uniform PL over the entire gel. A down‐conversion WLED built using the QDG emitter produces cool white light with a color temperature of 6100 K, a color rendering index of 94, and a luminous efficacy of 72 lm W −1 . In addition, the performance of the QDG‐based WLED remains unchanged even after more than 1000 bending/stretching cycles.
Electrochemical deposition of dopamine-hyaluronic acid conjugates onto electrode surfaces can lead to preserved electrochemical activities and anti-biofouling properties of the electrodes.
In this study, we demonstrated a strategy for fabricating unique 2D ternary nanohybrids comprising N-doped graphene (NG) and in-plane WSe2–WO3 (W–W) heterojunction nanosheets (NG/W–Ws) through heat treatment/oxidation processes using a graphene/PANI/WSe2 precursor. PANI served as an exfoliating and N-doping agent and played a crucial role along with graphene in developing a high effective surface area and pore volume. The NG/W–Ws showed a single kinetic reaction (the Volmer–Heyrovsky step) with a single onset potential for the hydrogen evolution reaction (HER) and decreased overpotentials; this was attributed to the intercalated NG. Density functional theory calculations indicated that NG decreases the energy gap between the LUMO and HOMO levels, and the differential Gibbs free energy of atomic hydrogen on the catalyst surface was close to zero. Therefore, the NG/W–Ws presented a linear relationship between their electrocatalytic performance (e.g., onset potential and overpotential) and mass loading (thickness). The total resistance and capacitance of the NG/W–Ws decreased and increased, respectively, with increasing electrode thickness, highlighting the synergy between the NG and W–W components. We believe that the proposed strategy will ensure the facile fabrication of multicomponent 2D heterostructured nanohybrids for high mass-loading electrocatalyst systems and will contribute to the practical commercialization of 2D nanohybrids as electrocatalysts.
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