Visible near-infrared chemosensor for mercury ion

A visible near-infrared chemosensor (MCy-1) for mercury ions was successfully devised and characterized. A large red-shift (122 nm) of the absorption maximum of MCy-1 was observed. An important feature for the new chemosensor is its high selectivity towards mercury ions over the other competitive species, making the "naked-eye" detection of mercury ions possible.     

Fluorescence Analysis with Quantum Dot Probes for Hepatoma Under One- and Two-Photon Excitation

A new class of fluorescent probe produced by conjugating semiconductor quantum dots (QDs) with protein molecule is proposed as an alternative to conventional organic labels. However the fluorescence characteristics of the QD bioconjugates are not clear while they are excitied with one- or two-photon laser pulse. We synthesized specific immunofluorescent probes by linking QDs to alpha fetoprotein (AFP) antibody for specific binding alpha-fetoprotein -an important marker for hepatocellular carcinoma cell lines, and archived specific fluorescence detection with the QDs-Anti-AFP in nude mice. Then, we have analyzed the fluorescence characteristics of QDs-Anti-AFP and original QDs both under one- and two-photon excitations. The results demonstrated that QDs-Anti-AFP's fluorescent spectral and lifetime haven't varied much from that of original QDs. Moreover, QDs-Anti-AFP have exhibited higher fluorescence efficiency than QDs under two-photon examination.     

Radical‐induced oxidation of RAFT agents—A kinetic study

Radical‐induced oxidation of reversible addition‐fragmentation chain transfer (RAFT) agents is investigated with respect to the effect of molecular structure on oxidation rate. The radicals are generated by homolysis of either azobisisobutyronitrile or alkoxyamine and transformed in situ immediately into peroxy radicals through transfer to molecular oxygen. It is found that the oxidation rate depends on the structure of Z‐ and R‐group of thiocarbonylthio compounds. For dithioesters with identical Z‐phenyl substituent, the oxidation rate decreases in the order of cyanoisopropyl (? C(Me)₂CN) > cumyl (? C(Me)₂Ph) > phenylethyl (? CH(Me)Ph) > 2‐methoxy‐1‐methyl‐2‐oxoethyl (? CH(Me) ? C(?O)OCH₃) > benzyl (? CH₂Ph). For dithioesters with identical R‐group, the oxidation rate decreases in the order of Z = phenyl? ～ benzyl? > RS? (trithiocarbonates) > RO? (xanthates). The stability of the RAFT agents toward oxidation correlates well with the chain transfer abilities as those previously reported by Rizzardo and coworkers. The priority of the oxidation reaction over the RAFT process, and the subsequent influence on RAFT polymerization are also investigated. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Electroactive organic anion‐doped polypyrrole as a low cost and renewable cathode for sodium‐ion batteries

We demonstrate here a remarkable electrochemical activation of polypyrrole chains by doping with redox‐active diphenylamine sulfonate anions. The organic redox dopant can not only serve as anionic counterions to enhance electrochemical activity of the polymer chains, but also contributes their redox capacity to the material. This organic‐polymer composite exhibits a quite high reversible capacity of 115 mA h g^?1, excellent rate capability and cycling stability, capable of serving as a low cost, and renewable cathode for Na‐ion batteries. Since the chemical doping method is simple and easily extendable for a large variety of organic anions and polymer networks, it is possible to adopt this new strategy for creating low cost and electrochemically active polymer materials for widespread electric storage applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Self-assembly of ABC star triblock copolymer thin films confined with a preferential surface: a self-consistent mean field theory

The microphase separation and morphology of a nearly symmetric A(0.3)B(0.3)C(0.4) star triblock copolymer thin film confined between two parallel, homogeneous hard walls have been investigated by self-consistent mean field theory (SCMFT) with a pseudospectral method. Our simulation experiments reveal that under surface confinement, in addition to the typically parallel, perpendicular, and tilted cylinders, other phases such as lamellae, perforated lamellae, and complex hybrid phases have been found to be stable, which is attributed to block-substrate interactions, especially for those hybrid phases in which A and B blocks disperse as spheres and alternately arrange as cubic CsCl structures, with a network preferred structure of C block. The results show that these hybrid phases are also stable within a broad hybrid region (H region) under a suitable film thickness and a broad field strength of substrates because their free energies are too similar to being distinguished. Phase diagrams have been evaluated by purposefully and systematically varying the film thickness and field strength for three different cases of Flory-Huggins interaction parameters between species in the star polymer. We also compare the phase diagrams for weak and strong preferential substrates, each with a couple of opposite quality, and discuss the influence of confinement, substrate preference, and the nature of the star polymer on the stability of relatively thinner and thick film phases in this work.     

Fluorescence Logic‐Signal‐Based Multiplex Detection of Nucleases with the Assembly of a Cationic Conjugated Polymer and Branched DNA

An energy‐transfer cascade is generated from a cationic conjugated polymer (PFP) and negatively charged, Y‐shaped DNA labeled with three dyes at its termini (fluorescein (Fl), Tex Red, and Cy5). Multistep fluorescence resonance energy transfer regulates the fluorescence intensities of PFP and the dyes. Different types of logic gates can be operated by observing the emission wavelengths of different dyes with multiplex nucleases as inputs.

     

Fluorescent Alteration on a Bistable Molecular Shuttle

Solvent driven molecular shuttles containing a pyrene‐connected macrocycle and an intramolecular charge‐transfer (ICT) chromophore stopper are constructed. In one of the molecular shuttles, a long C‐10 chain is introduced in the thread to separate the peptide station and the ICT stopper. The macrocycle stays in the peptide station in apolar solvents and moves to the C10‐chain station in highly polar solvents. This moving process alters the electronic interaction between the pyrene unit in the macrocycle and the ICT stopper, which induces the change of the pyrene fluorescence emission. The molecular shuttle exhibits stronger emission when the macrocycle is adjacent to the ICT stopper.     

Stabilization and Large Nonlinearity of Gold Nanoparticles Functionalized with a π‐Conjugated Polymer

Gold nanoparticles protected by a novel π‐conjugated polymer [poly(p‐phenylene ethynylene) containing pendent disulfide and bipyridine groups] are synthesized and characterized. The polymer can stabilize the gold nanoparticles effectively. The nonlinear optical properties of the gold nanoparticle colloid solutions in toluene are investigated by using the Z‐scan technique at a wavelength of 532 nm and pulse width of 4 ns. The gold‐nanoparticle colloid solutions show an exceptional nonlinear absorption effect, which simultaneously contains the saturated absorption resulting from third‐order nonlinearity and a large reverse‐saturated absorption resulting from fifth‐order nonlinearity. In addition, asymmetric self‐focusing refractive effects are investigated in the colloid solutions.     

Study on ride comfort of tractor with tandem suspension based on multi-body system dynamics

The aim of the paper is to report a systematic methodology which is used to evaluate and improve the ride comfort. An accurate model is necessary for further investigation and optimization. The vehicle dynamics model of tractor with tandem suspension is modeled and simulated in dynamics software ADAMS, which is redeveloped to add a function of automatic parametric modeling and simulation. The modeling methods of nonlinear characteristic components and various road excitation inputs, which can be simply seen as the implementation means for the model solution, are introduced. A new index called annoyance rate is presented to indicate the quantitative correlation between objective method and subjective comment. The quantitative correlation between them, which is quite different from the qualitative “comfortable” or “uncomfortable” results attained by objective evaluation, can be defined by function and regarded as a basis to scientifically evaluate and improve the ride comfort. According to the request of performance-based design, the parameter sensitive analysis and structure optimization have been carried out to find the trade-off among ride comfort, maneuverability and safety. The approach has proved to be very effective for predicting and improving the ride comfort by experiment results. The methodology can be also used for any other specific category of vehicle.