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51.
Cheng‐An Tseng Jhong‐Sian Wu Tai‐Yen Lin Wei‐Shun Kao Cheng‐En Wu So‐Lin Hsu Yun‐Yu Liao Prof. Dr. Chain‐Shu Hsu Huan‐Yi Huang Prof. Dr. You‐Zung Hsieh Prof. Dr. Yen‐Ju Cheng 《化学:亚洲杂志》2012,7(9):2102-2110
A pentacyclic benzodipyrrolothiophene ( BDPT ) unit, in which two outer thiophene rings are covalently fastened with the central phenylene ring by nitrogen bridges, was synthesized. The two pyrrole units embedded in BDPT were constructed by using one‐pot palladium‐catalyzed amination. The coplanar stannylated Sn‐BDPT building block was copolymerized with electron‐deficient thieno[3,4‐c]pyrrole‐4,6‐dione ( TPD ), benzothiadiazole ( BT ), and dithienyl‐diketopyrrolopyrrole ( DPP ) acceptors by Stille polymerization. The bridging nitrogen atoms make the BDPT motif highly electron‐abundant and structurally coplanar, which allows for tailoring the optical and electronic properties of the resultant polymers. Strong photoinduced charge‐transfer with significant band‐broadening in the solid state and relatively higher oxidation potential are characteristic of the BDPT‐based polymers. Poly(benzodipyrrolothiophene‐alt‐benzothiadiazole) ( PBDPTBT ) achieved the highest field‐effect hole mobility of up to 0.02 cm2 V?1 s?1. The photovoltaic device using the PBDPTBT /PC71BM blend (1:3, w/w) exhibited a Voc of 0.6 V, a Jsc of 10.34 mA cm?2, and a FF of 50 %, leading to a decent PCE of 3.08 %. Encouragingly, the device incorporating poly(benzodipyrrolothiophene‐alt‐thienopyrrolodione) ( PBDPTTPD )/PC71BM (1:3, w/w) composite delivered a highest PCE of 3.72 %. The enhanced performance arises from the lower‐lying HOMO value of PBDPTTPD to yield a higher Voc of 0.72 V. 相似文献
52.
Nattakan Soykeabkaew Chandeep Sian Saharman Gea Takashi Nishino Ton Peijs 《Cellulose (London, England)》2009,16(3):435-444
All-cellulose nanocomposites using bacterial cellulose (BC) as a single raw material were prepared by a surface selective
dissolution method. The effect of the immersion time of BC in the solvent (lithium chloride/N,N-dimethylacetamide) during preparation on the nanocomposite properties was investigated. The structure, morphology and mechanical
properties of the nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and tensile testing.
The optimum immersion time of 10 min allowed the preparation of nanocomposites with an average tensile strength of 411 MPa
and Young’s modulus of 18 GPa. With the longest immersion time of 60 min, the prepared composite sheet turns to express a
very high toughness characteristic possessing a work-to-fracture as high as 16 MJ/m3. These biobased nanocomposites show high performances thanks to their unique structure and properties. 相似文献
53.
Kaai‐Tung Chan Tsz‐Lung Lam Daohong Yu Lili Du David Lee Phillips Chun‐Lam Kwong Glenna So Ming Tong Gang Cheng Chi‐Ming Che 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15038-15042
Metal‐TADF (thermally activated delayed fluorescence) emitters hold promise in the development of next generation light‐emitting materials for display and lighting applications, examples of which are, however, largely confined to CuI and recently AuI, AgI, and AuIII emitters. Herein is described the design strategy for an unprecedented type of metal‐TADF emitter based on inexpensive tungsten metal chelated with Schiff base ligand that exhibit high emission quantum yields of up to 56 % in solutions and 84 % in thin‐film (5 wt % in 1,3‐bis(N‐carbazolyl)benzene, mCP) at room temperature. Femtosecond time‐resolved emission (fs‐TRE) spectroscopy and DFT calculations were undertaken to decipher the TADF properties. Solution‐processed OLEDs fabricated with the W‐TADF emitter demonstrated external quantum efficiency (EQE) and luminance of up to 15.6 % and 16890 cd m?2, respectively. 相似文献
54.
We revisit the classical problem of granular hopping conduction’s σ∝exp[–(T0/T)] temperature dependence, where σ denotes conductivity, T is temperature, and T0 is a sample-dependent constant. By using the hopping conduction formulation in conjunction with the incorporation of the random potential that has been shown to exist in insulator-conductor composites, it is demonstrated that the widely observed temperature dependence of granular hopping conduction emerges very naturally through the immediate-neighbor critical-path argument. Here, immediate-neighbor pairs are defined to be those where a line connecting two grains does not cross or by-pass other grains, and the critical-path argument denotes the derivation of sample conductance based on the geometric percolation condition that is marked by the critical conduction path in a random granular composite. Simulations based on the exact electrical network evaluation of finite-sample conductance show that the configurationaveraged results agree well with those obtained using the immediate-neighbor critical-path method. Furthermore, the results obtained using both these methods show good agreement with experimental data on hopping conduction in a sputtered metal-insulator composite Agx(SnO2)1–x, where x denotes the metal volume fraction. The present approach offers a relatively straightforward and simple explanation for the temperature behavior that has been widely observed over diverse material systems, but which has remained a puzzle in spite of the various efforts made to explain this phenomenon. 相似文献
55.
<正>Mechanics plays a crucial role in a diversity of biological processes at different length(from molecules,cells,tissues,organs to organisms)and time scales.As a rapidly growing field across the interfaces of mechanics,biology,and medical engineering,mechanobiology aims to identify the mechanical and biological responses of cells and tissues of 相似文献
56.
Michael E. Cooper Susan Gregory Elaine Adie Sian Kalinka 《Journal of fluorescence》2002,12(3-4):425-429
A series of functionalized, water-soluble, pH-sensitive pentamethine cyanine (CyTM5) dyes has been designed and synthesized. These probes are fluorescent in acidic media but are non-fluorescent in an alkaline environment. Subtle changes to the structure of these probes can lead to pronounced changes in the pKa of these probes. These probes have been utilized in a cellular environment to detect localized changes in pH using the IN Cell Analyzer, a confocal imager formatted for imaging of cell-based assays. 相似文献
57.
Sian Genoud Michael W. M. Jones Benjamin Guy Trist Junjing Deng Si Chen Dominic James Hare Kay L. Double 《Chemical science》2020,11(33):8919
Examining chemical and structural characteristics of micro-features in complex tissue matrices is essential for understanding biological systems. Advances in multimodal chemical and structural imaging using synchrotron radiation have overcome many issues in correlative imaging, enabling the characterization of distinct microfeatures at nanoscale resolution in ex vivo tissues. We present a nanoscale imaging method that pairs X-ray ptychography and X-ray fluorescence microscopy (XFM) to simultaneously examine structural features and quantify elemental content of microfeatures in complex ex vivo tissues. We examined the neuropathological microfeatures Lewy bodies, aggregations of superoxide dismutase 1 (SOD1) and neuromelanin in human post-mortem Parkinson''s disease tissue. Although biometals play essential roles in normal neuronal biochemistry, their dyshomeostasis is implicated in Parkinson''s disease aetiology. Here we show that Lewy bodies and SOD1 aggregates have distinct elemental fingerprints yet are similar in structure, whilst neuromelanin exhibits different elemental composition and a distinct, disordered structure. The unique approach we describe is applicable to the structural and chemical characterization of a wide range of complex biological tissues at previously unprecedented levels of detail.Structural and chemical characterisation of microfeatures in unadulterated Parkinson''s disease brain tissue using synchrotron nanoscale XFM and ptychography. 相似文献
58.
Barclay J. Elaine Davies Sian C. Evans David J. Fairhurst Shirley A. Fowler Christabel Henderson Richard A. Hughes David L. Oglieve Kay E. 《Transition Metal Chemistry》1998,23(6):701-713
A series of complexes of stoichiometry [MX2(dipyS)] {dipyS = bis(2–picolyl)-1,3–dithiopropane); M=Cr, Mn, Fe, Co, Ni, X=Cl; M=Ni or Cu, X=NO3} and [VOCl(dipyS)]Cl have been prepared and characterised, including the X-ray crystal structure of [Ni(ONO2)2(dipyS)]. The kinetics of the transfer of dipyS from these complexes (M=Cr, Mn, Fe, Co or Ni) to Cu2+, to form [Cu(dipyS)]2+, have been studied in MeOH. For M=Ni, the kinetics are consistent with a mechanism involving rate-limiting dissociation of the initial pyridyl—M bond. Subsequent binding of Cu2+ to the pendant pyridyl-residue (or binding Cl– to the vacant site on M) is followed by the complete transfer of dipyS from M to Cu. For M=Cr, Mn or Co, the same mechanism is believed to operate, but in these cases intermediates in the dipyS transfer to Cu2+ have been detected spectroscopically. Evidence is presented that these intermediates have Cu2+ bound to a pendant pyridyl-group on [MCl2(dipyS)] and that the subsequent complete transfer of dipyS involves rate-limiting dissociation of a M—S bond. For M=Fe, e.p.r. spectroscopy shows that the complex is a dimer in solution. However, the transfer reaction with Cu2+ involves an analogous intermediate to that with M=Cr, Mn or Co, but only at high concentrations of Cu2+. Unexpectedly, the binding of Cu2+ inhibits the transfer of dipyS from Fe to Cu. The electronic factors which give rise to this behaviour are discussed. 相似文献
59.
Jing Liang Guangxue Feng Ryan Tsz Kin Kwok Dan Ding Benzhong Tang Bin Liu 《中国科学:化学(英文版)》2016,59(1):53-61
Fluorescent light-up probes comprising a tetraphenylethene unit with aggregation-induced emission (AIE) characteristics and a water-soluble peptide have been designed and synthesized which provide cell membrane and nuclear permeability to live cells. This strategy has offered new opportunities for the development of probes with light-up ability and good signal-to-noise ratio. The selectivity or targeting specificity is determined by the peptide sequence, i.e. a nuclear localization signal that leads to nucleus imaging and a cell biomarker targeting peptide that offers specific light-up imaging of HT-29 cells. 相似文献
60.
Cooper SM Cox RJ Crosby J Crump MP Hothersall J Laosripaiboon W Simpson TJ Thomas CM 《Chemical communications (Cambridge, England)》2005,(9):1179-1181
Mutation of the mupW gene in the mupirocin biosynthetic gene cluster in Pseudomonas fluorescens results in efficient production of a novel pseudomonic acid metabolite, mupirocin W, which lacks the characteristic tetrahydropyran ring, and reveals the role of the mupW gene in pseudomonic acid biosynthesis. 相似文献