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991.
Seunggun Yu Do-Kyun Kim Cheolmin Park Soon Man Hong Chong Min Koo 《Research on Chemical Intermediates》2014,40(1):33-40
A study was performed to determine the effect of the content and orientation of fillers on the thermal conductivity of a polymeric composite packed with hexagonal boron nitride (hBN) and silicon carbide (SiC) fillers. The thermal conductivity behavior of SiC–Nylon 6,6 and hBN–Nylon 6,6 composites was more dependent on the orientation and shape of the filler than on its thermal conductivity. The thermal conductivity of SiC–Nylon 6,6 composites with 59 % (v/v) isotropic SiC fillers increased from 0.25 to 3.83 W/m K. That of hBN–Nylon 6,6 composites with 62 % (v/v) anisotropic hBN fillers increased from 0.25 to 2.16 W/m K in the perpendicular direction whereas in the parallel direction it increased rapidly to 8.55 W/m K . 相似文献
992.
Eun-Sil Park Dae-Hwan Jang Young-In Lee Chan Woo Jung Dong woo Lim Bum Sung Kim Young-keun Jeong Nosang V. Myung Yong-Ho Choa 《Research on Chemical Intermediates》2014,40(7):2565-2570
Conducting polymers are excellent sensing materials in the design of bioanalytical sensors because of their electronic conductivity, low energy optical transitions, biocompatibility, and room temperature operation. Among them, Polypyrrole (Ppy) is one of the most extensively used conducting polymers because of a number of properties such as redox activity, rapid electron transfer, and ability to link a variety of biomolecules to pyrrole groups by chemical treatment. In this study, Ppy nanowires were synthesized by an electrospinning method. The nanowires were prepared from a solution mixture of Ppy and poly(ethylene oxide). The method of detection in such a device is based on the selective binding of antigen onto an antibody that is covalently attached to the nanowires. Thus, anti-IgG was immobilized on Ppy nanowires using an EDC {[N-(3-dimethyl aminopropyl)-N2-ethylcarbodiimide hydrochloride]}-NHS(N-hydrosuccinimide) modified technique. Fluorescence images of BSA–FITC (fluorescein isothiocyanate labeling of bovine serum albumin) conjugation demonstrated that antibody was functionalized on the Ppy nanowires without non-specific binding and facilitated selective detection of antigen. Current–voltage (I–V) characterization was used to monitor the change in the conductivity of nanowires while the specific binding interaction occurred. These results of electrical properties enable Ppy nanowire-based biosensors to detect biomolecules in real-time. 相似文献
993.
Sung-Soo Kim 《Research on Chemical Intermediates》2014,40(7):2553-2558
Magnetic and dielectric loss have been systematically controlled by using two kinds of high-permeability particles with different electrical conductivity (Sendust, Permalloy), and the effect of the magnetic and dielectric loss on the noise-absorbing properties has been investigated. Noise-absorbing sheets are composite materials of magnetic flake particles of high aspect ratio dispersed in a polymer matrix. The frequency dispersion of the complex permeability was almost the same for the Sendust and Permalloy composite specimens. However, the complex permittivity of the Permalloy composite (ε r′ ≈ 250, ε r″ ≈ 50) was much greater than that of the Sendust composite (ε r′ ≈ 70, ε r″ ≈ 0). Enhancement of the space-charge polarization between the highly conductive Permalloy particles results in the high values of ε r′ and ε r″. Due to the large dielectric loss of the Permalloy composite (in addition to its inherent magnetic loss), the bandwidth of noise absorption is increased, especially in the lower frequency region. Dielectric loss should be considered in the design of broad-bandwidth noise-absorbing composites. 相似文献
994.
Polyaniline (PANI)/graphene nanosheet (GNS) composites were prepared by a chemical oxidation polymerization. The morphology, structure, and crystallinity of the composites were examined by scanning electron microscopy, transition electron microscopy, and X-ray diffraction. Electrochemical properties were characterized by cyclic voltammetry in 1 M H2SO4 electrolyte. GNS are considered as supporting materials which can provide a large number of active sites. The PANI nanofibers with diameter of 50 nm were homogeneously coated on the surface of GNS. The PANI/GNS composites exhibited a better electrochemical performance than the pure individual components. The PANI/GNS composites showed the highest specific capacitance 923 Fg?1 at 10 mVs?1 compared to 465 Fg?1 for pure PANI and 99 Fg?1 for GNS. 相似文献
995.
Dr. Emiko Kazuma Minhui Lee Prof. Jaehoon Jung Prof. Michael Trenary Dr. Yousoo Kim 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):8034-8040
Chemical reactions induced by plasmons achieve effective solar-to-chemical energy conversion. However, the mechanism of these reactions, which generate a strong electric field, hot carriers, and heat through the excitation and decay processes, is still controversial. In addition, it is not fully understood which factor governs the mechanism. To obtain mechanistic knowledge, we investigated the plasmon-induced dissociation of a single-molecule strongly chemisorbed on a metal surface, two O2 species chemisorbed on Ag(110) with different orientations and electronic structures, using a scanning tunneling microscope (STM) combined with light irradiation at 5 K. A combination of quantitative analysis by the STM and density functional theory calculations revealed that the hot carriers are transferred to the antibonding (π*) orbitals of O2 strongly hybridized with the metal states and that the dominant pathway and reaction yield are determined by the electronic structures formed by the molecule–metal chemical interaction. 相似文献
996.
Light-Driven Crawling of Molecular Crystals by Phase-Dependent Transient Elastic Lattice Deformation
Yanjun Gong Yongxian Guo Fayuan Ge Wei Xiong Jie Su Yang Sun Chuang Zhang An-Min Cao Yifan Zhang Jincai Zhao Yanke Che 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10423-10428
The light-driven crawling of a molecular crystal that can form three phases, (α, β, and γ) is presented. Laser irradiation of the molecular crystal can generate phase-dependent transient elastic lattice deformation. The resulting elastic lattice deformation that follows scanning irradiation of a laser can actuate the different phases of molecular crystal to move with different velocity and direction. Because the γ phase has a large Young's modulus (ca. 26 GPa), a force of 0.1 μN can be generated under one laser spot. The generated force is sufficient to actuate the γ-formed molecular crystals in a wide dimensional range to move longitudinally at a velocity of about 60 μm min−1, which is two orders of magnitude faster than the α and β phases. 相似文献
997.
Meiling Chen Chenxi Peng Yaoquan Su Xue Chen Prof. Yuezhou Zhang Prof. Yu Wang Prof. Juanjuan Peng Dr. Qiang Sun Prof. Xiaowang Liu Prof. Wei Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21174-21181
The ability to incorporate functional metal ions (Mn+) into metal–organic coordination complexes adds remarkable flexibility in the synthesis of multifunctional organic–inorganic hybrid materials with tailorable electronic, optical, and magnetic properties. We report the cation-exchanged synthesis of a diverse range of hollow Mn+-phytate (PA) micropolyhedra via the use of hollow Co2+-PA polyhedral networks as templates at room temperature. The attributes of the incoming Mn+, namely Lewis acidity and ionic radius, control the exchange of the parent Co2+ ions and the degree of morphological deformation of the resulting hollow micropolyhedra. New functions can be obtained for both completely and partially exchanged products, as supported by the observation of Ln3+ (Ln3+=Tb3+, Eu3+, and Sm3+) luminescence from as-prepared hollow Ln3+-PA micropolyhedra after surface modification with dipicolinic acid as an antenna. Moreover, Fe3+- and Mn2+-PA polyhedral complexes were employed as magnetic contrast agents. 相似文献
998.
Jihyeon Kim Jongkyoon Park Dr. Seonhwa Park Jeongwook Seo Jeongwook Kwon Hyunsoo Lee Prof. Dr. Seungchul Kim Prof. Dr. Haesik Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(43):19364-19370
Distance-dependent electromagnetic radiation and electron transfer have been commonly employed in washing-free fluorescence and electrochemical bioassays, respectively. In this study, we combined the two distance-dependent phenomena for sensitive washing-free DNA detection. A distance-dependent surface plasmonic field induces rapid photoredox catalysis of surface-bound catalytic labels, and distance-dependent mediated electron transfer allows for rapid electron transfer from the surface-bound labels to the electrode. An optimal system consists of a chemically reversible acceptor (Ru(NH3)63+), a chemically reversible photoredox catalyst (eosin Y), and a chemically irreversible donor (triethanolamine). Side reactions with O2 do not significantly decrease the efficiency of photoredox catalysis. Energy transfer quenching between the electrode and the label can be lowered by increasing the distance between them. Washing-free DNA detection had a detection limit of approximately 0.3 nm in buffer and 0.4 nm in serum without a washing step. 相似文献
999.
Dr. Hua Su Ben Niu Haoran Li Dr. Fei Liu Tinglian Yuan Prof. Hong-Yuan Chen Prof. Wei Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(43):19371-19376
The ordered assembly of molecules within a specific space of nanoscale, such as a surface, holds great promise in advanced micro-/nanostructure fabrication for various applications. Herein, we demonstrate the evanescent wave (EW)-guided organization of small molecules into a long-range ordered nanowire (NW) array. Experiment and simulation revealed that the orientation and periodicity of the NW array were feasibly regulated by altering the propagation direction and the wavelength of EW. The generality of this approach was demonstrated by using different molecule precursors. While existing studies on EW often took advantages of its near-field property for optical sensing, this work demonstrated the photochemical power of EW in the guided-assembly of small molecules for the first time. It also provides an enlightening avenue to periodic structure with fluorescence, promising for super-resolution microscopy and important devices applicable to optical and bio-related fields. 相似文献
1000.
Dr. Chao Ma Bo Li Dr. Baiqi Shao Dr. Baiheng Wu Prof. Dong Chen Dr. Juanjuan Su Prof. Hongjie Zhang Prof. Kai Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21665-21671
Hydrogels enable a variety of applications due to their dynamic networks, structural flexibility, and tailorable functionality. However, their mechanical performances are limited, specifically in the context of cellular mechanobiology. It is also difficult to fabricate robust gel networks with a long-term durability. Thus, a new generation of soft materials showing outstanding mechanical behavior for mechanobiology applications is highly desirable. We combined synthetic biology and supramolecular assembly to prepare elastin-like protein (ELP) organogel fibers with extraordinary mechanical properties. The mechanical performance and stability of the assembled anisotropic proteins are superior to other organo-/hydrogel systems. Bone-derived mesenchymal cells were introduced into the organofiber system for stem-cell lineage differentiation. This approach demonstrates the feasibility of mechanically strong and anisotropic organonetworks for mechanobiology applications and holds great potential for tissue-regeneration translations. 相似文献