Showing papers by "Zhen Li published in 2007"
TL;DR: In this article, nonemissive tetraphenylethene (TPE) 1 and diphenylated derivative 2 were induced to emit intensely by aggregate formation and they were turned on at ∼2.9 and ∼5V and emitted blue lights with maximum luminance of ∼1800 and ∼11000cd∕m2, respectively.
Abstract: Nonemissive tetraphenylethene (TPE) 1 and its diphenylated derivative 2 were induced to emit intensely by aggregate formation. Crystalline aggregates of the dyes emitted bluer lights than their amorphous counterparts. The emissions of the TPE dyes could be switched off and on continuously and reversibly by wetting and dewetting with solvent vapors, respectively, manifesting their ability to optically sense volatile organic compounds. The light-emitting diodes fabricated from 1 and 2 were turned on at ∼2.9 and ∼5V and emitted blue lights with maximum luminance of ∼1800 and ∼11000cd∕m2, respectively.
470 citations
TL;DR: Photoluminescence of simple arylbenzenes with ready synthetic accessibility is enhanced by two orders of magnitude through aggregate formation; viscosity and temperature effects indicate that the emission enhancement is due to the restriction of their intramolecular rotations in the solid state.
377 citations
TL;DR: (4-Biphenylyl)phenyldibenzofulvene is weakly luminescent in the amorphous phase but becomes highly emissive upon crystallization; this unusual crystallization-induced emission enhancement effect allows its emission to be repeatedly switched between dark and bright states by fuming-heating and heating-cooling processes.
373 citations
TL;DR: The possibility of utilizing the AIE effect for protein detection and quantification is explored using bovine serum albumin (BSA) as a model protein, with salt 3 being found to perform as a stable, sensitive, and selective bioprobe.
Abstract: Three functionalized derivatives of tetraphenylethylene (TPE), namely, 1,2-bis(4-methoxyphenyl)-1,2-diphenylethene (1), 1,2-bis(4-hydroxyphenyl)-1,2-diphenylethene (2), and 1,2-bis[4-(3-sulfonatopropoxyl)phenyl]-1,2-diphenylethene sodium salt (3), were synthesized and their fluorescence properties were investigated. All the TPE molecules are nonluminescent in the solution state but are induced to emit efficiently by aggregate formation. This novel process of aggregation-induced emission (AIE) is rationalized to be caused by the restriction of intramolecular rotations of the dye molecules in the aggregate state. The possibility of utilizing the AIE effect for protein detection and quantification is explored using bovine serum albumin (BSA) as a model protein, with salt 3 being found to perform as a stable, sensitive, and selective bioprobe.
308 citations
TL;DR: 1,2-Diphenyl-3,4-bis(dipenylmethylene)-1-cyclobutene can be induced to emit efficiently by aggregate formation, with the crystalline aggregates emitting brighter, bluer lights than their amorphous counterparts.
250 citations
140 citations
TL;DR: The tested NLO properties of the polymers demonstrate that there is a suitable isolation group present for the sulfonyl-based chromophore to boost its microscopic beta value to a possibly higher macroscopic NLO property efficiently.
Abstract: For the first time, the indole-based NLO chromophores were embedded into the polymer main chain, and different isolation groups were attached to their donor side with the efforts of adjusting the NLO properties of the resultant main-chain polyurethanes, according to the site isolation principle. Thanks to the main-chain structure and the advantages of the indole-based chromophores, all the polymers show excellent transparency, good processability, thermal stability, and relatively good NLO effects. The tested NLO properties of the polymers demonstrate that there is a suitable isolation group present for the sulfonyl-based chromophore to boost its microscopic beta value to a possibly higher macroscopic NLO property efficiently.
82 citations
15 Jul 2007
TL;DR: The successful conjugation between the magnetite nanocrystals and 9-amino acridine demonstrates the existence of free carboxylic groups from PEG binding on the particle surface, and may also lead to a new type of magneto-optical materials as well as Magneto-drugs.
Abstract: By one-pot reaction, biocompatible magnetite nanocrystals with surface reactive moieties were prepared through the thermal decomposition of Fe(acac)3 in 2-pyrrolidone using α , ω -dicarboxyl-terminated poly(ethylene glycol) as surface capping molecule. The successful conjugation between the magnetite nanocrystals and 9-amino acridine on the one hand demonstrates the existence of free carboxylic groups from PEG binding on the particle surface, on the other hand may also lead to a new type of magneto-optical materials as well as magneto-drugs.
61 citations
TL;DR: A series of main-chain polyurethanes containing sulfonyl-based NLO chromophores in the polymer backbone were prepared, the subtle structure of the chromophore moieties could be easily modified to adjust the property of the resultant polymers as mentioned in this paper.
60 citations
TL;DR: In this article, a facile synthetic strategy, consisting of the postazo coupling and esterification reactions, was developed to prepare a series of second-order nonlinear optical polyurethanes (P2-P5).
52 citations
Patent•
10 Dec 2007TL;DR: In this article, the authors described conjugated polyene compounds are useful as bioprobes for the detection biomacromolecules, as well as in the manufacture of sensors.
Abstract: The presently described subject matter is directed to water-soluble conjugated polyene compounds that exhibit aggregation induced emission, as well as to water dispersible, fluorescent, polymeric microparticles and/or nanoparticles comprising the water-soluble conjugated polyene compounds. Also provided are methods of making and using the compounds and particles. The described conjugated polyene compounds are useful as bioprobes for the detection biomacromolecules, as well as in the manufacture of sensors.
TL;DR: In this article, a copolycyclotrimerization of (E,E)-1, 1, 1'bis[2-(4-ethynylphenyl)vinyl]ferrocene was used to synthesize hyperbranched poly(ferrocenyl phenylenes) (hb-PFPs) with high molecular weights.
Abstract: Hyperbranched poly(ferrocenylphenylenes) (hb-PFPs) with high molecular weights were synthesized by the copolycyclotrimerizations of (E,E)-1,1‘-bis[2-(4-ethynylphenyl)vinyl]ferrocene (1) with (E)-1-[2-(4-ethynylphenyl)vinyl]ferrocene (2) catalyzed by TaCl5−Ph4Sn at room temperature in high yields (up to 97%). Effects of reaction conditions, such as monomer and catalyst concentrations, reaction time and molar feed ratio (r1/2), on the copolycyclotrimerization were investigated. Solubility of the copolymer is decreased with an increase in its content of diyne component (N1/N2). The hb-PFPs were characterized by IR, NMR, UV, CV and TGA analyses. The copolymers are redox active, whose oxidation potentials are decreased with an increase in N1/N2. They are thermally stable, losing ∼5% of weights when heated to 384−400 °C and retaining ∼70% of weights when pyrolyzed at 1200 °C. The complexation with cobalt carbonyl further metallizes the hb-PFPs and the pyrolytic ceramization of the cobalt−polymer complexes yield...
TL;DR: The characteristic expression pattern of rbp4 suggests that the YSL is patterned despite its syncytial nature, and Rbp4 plays a role in formation of both yolk extension and liver bud, the latter may also require migration of liver progenitor cells.
Abstract: The number of genes characterized in liver development is steadily increasing, but the origin of liver precursor cells and the molecular control of liver formation remain poorly understood. Existing theories about formation of zebrafish visceral organs emphasize either their budding from the endodermal rod or formation of independent anlage followed by their later fusion, but none of these is completely satisfactory in explaining liver organogenesis in zebrafish. Expression of a gene encoding the retinol binding protein 4 (Rbp4) was analyzed in zebrafish. rbp4, which is expressed mainly in the liver in adults, was shown to be expressed in the yolk syncytial layer (YSL) during early embryogenesis. At 12–16 hpf rbp4 expression was restricted to the ventro-lateral YSL and later expanded to cover the posterior YSL. We demonstrated that rbp4 expression was negatively regulated by Nodal and Hedgehog (Hh) signalling and positively controlled by retinoic acid (RA). Knockdown of Rbp4 in the YSL resulted in shortened yolk extension as well as the formation of two liver buds, which could be due to impaired migration of liver progenitor cells. rbp4 appears also to regulate the extracellular matrix protein Fibronectin1 (Fn1) specifically in the ventro-lateral yolk, indicating a role of Fn1 in liver progenitor migration. Since exocrine pancreas, endocrine pancreas, intestine and heart developed normally in Rbp4 morphants, we suggest that rbp4 expression in the YSL is required only for liver development. The characteristic expression pattern of rbp4 suggests that the YSL is patterned despite its syncytial nature. YSL-expressed Rbp4 plays a role in formation of both yolk extension and liver bud, the latter may also require migration of liver progenitor cells.
TL;DR: In this article, the effects of solvent vapor on the photoluminescence (PL) of 2,3,4,5-tetraphenylsiloles carrying different 1,1-substituents were investigated.
Abstract: Effects of solvent vapor on the photoluminescence (PL) of 2,3,4,5-tetraphenylsiloles carrying different 1,1-substituents [(PhC)4SiRR′, R = Ph, R′ = CH3 (2); R = Ph, R′ = C≡CH (3); R = R′ = C≡CH (4)] were investigated. The emission of the silole spots on the TLC plates can be turned “off” and “on” continuously and reversibly by wetting by, and de-wetting from, vapors of organic solvents, respectively. After fumigation by solvent vapor, the thin film of 4 coated on the quartz substrate emits stronger and bluer PL owing to the transformation of film morphology from the amorphous to the crystalline phase. Analysis by X-ray diffraction reveals that the molecular conformations of the crystals of 2–4 are locked and stabilized by multiple C–H···π hydrogen bonds. This structural rigidification has made the silole crystals stronger emitters.
TL;DR: A simple method to fabricate the one-dimensional nanostructure of zinc oxide nanorods from aqueous solution was presented in this paper, where the results indicated that the ZnO nanorod were single crystalline and grown in the direction of [001] with the hexagonal wurtzite structure.
TL;DR: It can be concluded that USPIO enhancement of the toxoplasmic lesions may reflect blood-brain barrier impairment and/or inflammatory reactions associated with these lesions and improve the differential diagnosis of toxoplasmsosis encephalitis.
TL;DR: The total activity variation with depth from a 41.6 m Muztagata ice core, measured at 7010 m, recorded not only the 1963 radioactive layer due to the thermonuclear test, but also clearly the radioactive peak released by the Chernobyl accident in 1986 as mentioned in this paper.
Abstract: The total activity variation with depth from a 41.6 m Muztagata ice core drilled at 7010 m, recorded not only the 1963 radioactive layer due to the thermonuclear test, but also clearly the radioactive peak released by the Chernobyl accident in 1986. This finding indicates that the Chernobyl nuclear accident was clearly recorded in alpine glaciers in the Pamirs of west China, and the layer can be potentially used for ice core dating in other high alpine glaciers in the surrounding regions.
TL;DR: In this article, the synthesis and magnetism of a new polymer-inorganic intercalation nanocomposite based on a C 60 -containing poly(ethylene oxide) (C 60 -PEO) into layered MnPS 3, which is characterized by XRD, IR and thermal analyses, is reported.
12 Dec 2007
TL;DR: A two-step greedy generalization algorithm is used to carry out the multiple sensitive attributes processing which deal with quasi-identifiers and sensitive attributes respectively, and the overall distortion is reduced by the measure of Masking SA.
Abstract: In recent years, a privacy model called k-anonymity has gained popularity in the microdata releasing. As the microdata may contain multiple sensitive attributes about an individual, the protection of multiple sensitive attributes has become an important problem. Different from the existing models of single sensitive attribute, extra associations among multiple sensitive attributes should be invested. Two kinds of disclosure scenarios may happen because of logical associations. The Q&S Diversity is checked to prevent the foregoing disclosure risks, with an α Requirement definition used to ensure the diversity requirement. At last, a two-step greedy generalization algorithm is used to carry out the multiple sensitive attributes processing which deal with quasi-identifiers and sensitive attributes respectively. We reduce the overall distortion by the measure of Masking SA.
TL;DR: In this article, two triaryl amino chromophores with tricyanovinyldihydrofuran groups as electronic acceptor are synthesized and found to exhibit blue-shifted absorption in comparison with the corresponding Dπ-A analogues while demonstrating significantly enhanced optical nonlinearity.
TL;DR: A polysiloxane P1 with pendant carbazoly groups and a high density of the pentafluorophenyl azo chromophore as side chain was synthesized in moderate yield by two successive postfunctionalization reaction including Vilsmeir formylated reaction and Knoevenagel condensation as mentioned in this paper.
Abstract: A new polysiloxane P1 with pendant carbazoly groups and a high density of the pentafluorophenyl azo chromophore as side chain was synthesized in moderate yield by two successive postfunctionalization reaction including Vilsmeir formylated reaction and Knoevenagel condensation. Its structure was verified by 1 H NMR, IR, and UV–Vis spectra. The polymer P1 exhibited good solubility in common organic solvents and was thermally stable up to 282 °C. The maximum absorption appeared at about 407 nm for P1 in THF, which was blue-shifted about 87 nm compared to the corresponding polysiloxane P2 with a well-known nitro acceptor azo chromophore, resulting in a wider transparency window. The value of the NLO coefficient d 33 of P1 thin film, measured by in situ second harmonic generation (SHG), was 11.9 pm/V. Preliminary photorefractive experiments showed that P1 obtained diffraction efficiency of 78% and a time constant of 1.19 sec.
TL;DR: In this article, a new polyphosphazenes (P2 and P3) that contain indole-based chromophore and binaphtholyl moieties as side chains are prepared by a new postfunctional strategy.
Abstract: New polyphosphazenes (P2 and P3) that contain indole-based chromophore and binaphtholyl moieties as side chains are prepared by a new postfunctional strategy. Molecular structural characterization for the high polymers was presented by 1H-NMR, IR and UV-Visible spectra, gel permeation chromatograply, and differential scanning calorimetry. The glass transition temperature of P2 was determined to be 168°C, higher than those polyphosphazenes reported previously in the literatures. P2 and P3 are thermal stable and easily soluble in high polar solvents. The maximum absorption of P2 in chloroform was at 425 nm and cuts off at about 550 nm, while that of P3 was 393 nm and 500 nm, respectively, which resulted in a wide transparency window. The poled films of P2 and P3 reveal a resonant d33 value of 20 pm/V and 14 pm/V, respectively, by second harmonic generation measurements. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 365–371, 2007
TL;DR: In this paper, a novel hyperbranched polymer (3) was prepared by copolymerization of tri-aldehyde moieties with azo chromophores having two active methelene groups, from A2+B3 approach based on simple Kneovenagel reaction.
Abstract: A novel hyperbranched polymer (3) was prepared by copolymerization of tri-aldehyde moieties with azo chromophores having two active methelene groups, from "A2+B3" approach based on simple Kneovenagel reaction. For comparison, its analogue linear polymer (5) was also synthesized. The two polymers are soluble in common organic solvents, and exhibit good thermal stability. Interestingly, the hyperbranched polymer demonstrates dramatically enhanced second-order nonlinear optical property with comparison to its linear analogue.
26 Nov 2007
TL;DR: Simulation results show that for typical mesh models, DECVQ can reduce PSNR degradation of about 3dB if the authors want to save 1 bit per vertex comparative to the conventional vertex encoding method with stationary codebooks.
Abstract: The transmission and storage of large amounts of vertex geometry data are required for rendering geometrically detailed 3D models. To alleviate bandwidth requirements, vector quantization (VQ) is an effective lossy vertex data compression technique for triangular meshes. With VQ methods based on stationary codebooks, we need codebooks of different levels to achieve the desired compression rate. However, it is not convenient to transmit or prestore codebooks of different levels in the Internet. This paper presents a novel vertex encoding algorithm using the dynamic extended codebook based vector quantization (DECVQ). In DECVQ, a parameter is used to control the encoding quality to get the desired compression rate in a range with only one codebook Simulation results show that for typical mesh models, DECVQ can reduce PSNR degradation of about 3dB if we want to save 1 bit per vertex (bpv) comparative to the conventional vertex encoding method with stationary codebooks.
08 Feb 2007
TL;DR: A group of organic chromophoric molecules including siloles, pyrans, tetraphenylethylenes and fulvenes, are designed and synthesized as mentioned in this paper and can be used as sensors for the detection of explosives, organic solvent vapors, solution pH, and biomacromolecules.
Abstract: A group of organic chromophoric molecules including siloles, pyrans, tetraphenylethylenes and fulvenes, are designed
and synthesized. Light emissions of conventional luminescent materials are often quenched by aggregate formation.
These molecules, however, become stronger luminophors when aggregated although they are practically nonemissive in
their dilute solutions. By varying their packing structures in the aggregation states, emission color ranging from blue to
red can be achieved. The emission of fulvenes can also be controlled by changing their morphology. While they emit a
faint light in the amorphous state, their crystal forms are strongly luminescent. Intermolecular interaction or restriction of
intramolecular rotation in different states may be responsible for such behaviors. Thanks to such effects, the molecules
can be employed as sensors for the detection of explosives, organic solvent vapors, solution pH, and biomacromolecules.
Further modification of their structures by molecular engineering endeavors may generate materials that can find an
array of applications in optical display systems and as biological probes.
TL;DR: In this article, a new electron beam radiation method was developed to prepare spinel-type nanocrystalline ZnFe2O4 at room temperature and ambient pressure, without any kind of catalysts.
Abstract: A new electron beam radiation method was developed to prepare spinel-type nanocrystalline ZnFe2O4 at room temperature and ambient pressure, without any kind of catalysts. The structure, morphology and size were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), infrared spectroscopy (IR). The obtained Nanocrystalline ZnFe2O4 particles have Spinel structure, spherical shape morphology and a mean particle size distribution of 20 and 40 nm.
TL;DR: In this paper, a novel synthetic strategy was developed to prepare polyphosphazenes containing C60 moieties, which exhibits good solubility in common organic solvents and is thermally stable.
Abstract: A novel synthetic strategy was developed to prepare polyphosphazenes containing C60 moieties. Thus, the phosphonitrile chloride trimer underwent thermal ring-opening polymerization (ROP) in the presence of C60 molecules to yield the reactive macromolecular intermediate, C60-containing poly(dichlorophosphazene). And then, the other groups could be linked to the phosphazene backbone by nucleophilic substitution reaction of the chlorine atoms in this intermediate to produce a series of C60-containing polyphosphazene. The polymer exhibits good solubility in common organic solvents and is thermally stable.
01 Jan 2007
TL;DR: In this article, the authors analyzed the coherence characteristics for different baseline, time interval with or without season change and different classes (rock, bare soil, vegetation, water), used 13 time-series ASAR data from Jan. 2004 to June 2006 at the Beiluhe test area in the Qinghai-Tibetan Plateau.
Abstract: The surface displacement by seasonally freezing bulge and thawing subsidence are main hazards for engineering construction in permafrost regions, especially for the Qinghai-Tibet railway. For detecting the distortion at permafrost area, we try to study the interferometric method of monitoring the deformation at permafrost area with time-series EnviSat ASAR data. In this paper, the coherence characteristics are analyzed for different baseline, time interval with or without season change and different classes (rock, bare soil, vegetation, water), used 13 time-series ASAR data from Jan. 2004 to June 2006 at the Beiluhe test area in the Qinghai-Tibetan Plateau. The results showed that the coherence coefficients is lower in summer and fall than in other two seasons as the freezing and thawing phenomenon. For pairs of crossed different season, such as from spring to summer or from summer to fall, the coherence coefficient decrease for bare soil and vegetation cover, little decrease for rock cover.