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971.
Three two‐photon absorption (TPA) tribranched chromophores were successfully prepared, in which 1,3,5‐triazine is been as electron deficient core, 1,4‐phenylenedivinylene as conjugated bridge, 3,4‐ethylenedioxythiophene (EDOT) ( T1 ), N‐methylpyrrole ( T2 ) or triphenylamine ( T3 ) as electron‐donating end‐groups. Their photophysical properties were studied by absorption, one‐ and two‐photon fluorescence and TPA cross‐section determination. The nonlinear transmission (NLT) measurement in femtoseconds (fs) regime at 800 nm indicates that TPA cross‐section (2 values of T1 , T2 and T3 with extended Π‐conjugated bridge are much larger than the corresponding chromophore T4 with a short length bridge, and TPA cross‐section of T1 with end‐groups EDOT exhibits a remarkable enhancement compared with T2 and T3 having the same length Π‐system. The chromophores T1 , T2 and T3 show also remarkable up‐converted luminescence and optical limiting activity. 相似文献
972.
The electrocatalysis oxidation of guanosine‐5′‐monophosphate (GMP) was investigated on Mg‐Al layered double hydroxide (LDH) functionalized with sodium dodecyl sulfate (SDS) and room temperature ionic liquid (RTIL) modified glass carbon electrode (GCE). The cyclic voltammogram of GMP on the modified electrode (RTIL/ LDH‐SDS/GCE) exhibited a well defined anodic peak at 1.091 V in 0.2 mol·L?1 pH 4.4 acetate buffer solution. The GMP oxidation was enhanced in the presence of anionic surfactant in the ?lms. The results suggest that the surfactant molecules intercalate the LDH layers to preconcentrate GMP molecules and the RTIL showed good ionic conductivity. The experimental parameters were optimized, the kinetic parameters were investigated and the probable oxidation mechanism was proposed. Under the optimized conditions, the oxidation peak current was proportional to GMP concentration in the range from 5.0×10?7 to 1.0×10?4 mol·L?1 with the correlation coefficient of 0.9987 and the detection limit was 1.0×10?7 mol·L?1. The RTIL/LDH‐SDS/GCE showed a good electrochemical response to the oxidation of GMP and would be developed into a new biosensor. 相似文献
973.
Fan Zhang Xin Zhai Li Juan Chen Jian Guo Qi Bo Cui Yu Cheng Gu Ping Gong 《中国化学快报》2011,22(11):1277-1280
A series of 2,5-disubstituted pyrimido[5,4-c]quinoline derivatives were synthesized and their cytotoxic activity against H460, HT-29 and MDA-MB-231 cell lines was evaluated in vitro.It was found that most of the tested compounds especially compound 17, shown stronger activity to the selected three cell lines than ZM447439. 相似文献
974.
Precipitation polymerizations of divinylbenzene(DVB) in pure supercritical carbon dioxide,and parallel runs with presence of a cosolvent were carried out.The results showed that use of acetone as the cosolvent contributed greatly to the formation of the monodisperse microspheres.PDVB microspheres,with obviously higher uniformity than reported up to date,were achieved using 6-7 mL of acetone in a reactor of 50 mL with DVB concentration of 0.4 mol/L under 16 MPa,a much lower pressure than previously reported without use of cosolvent. 相似文献
975.
Bo Liu Yi He Chunfeng Duan Na Li Hua Cui 《Journal of photochemistry and photobiology. A, Chemistry》2011,217(1):62-67
It was found that lucigenin alkaline solution could react with hydrazine in the presence of Pt nanoparticles to generate strong chemiluminescence (CL) centered at 480 nm. In order to explore the CL mechanism, UV–visible spectra, X-ray photoelectron spectra studies before and after the CL reaction were carried out. The effects of O2 and superoxide dismutase (SOD) on the CL reaction were examined. The catalytic effect of Pt NPs on the hydrazine–O2 reaction was studied. A possible mechanism is proposed to be due to that Pt NPs catalyzed the reaction between hydrazine and the dissolved oxygen under alkaline conditions to yield hydroperoxide species and superoxide radical anion, which further oxidized lucigenin to produce CL emission. Moreover, the effects of some organic compounds containing hydroxyl (OH), carboxyl (COOH), carbonyl (CO), amino (NH2), or sulfur groups on the lucigenin–hydrazine–Pt NPs CL system were tested. Thiol-containing compounds such as cysteine (Cys), glutathione (GSH), homocysteine (Hcy), and 6-mercaptopurine (6-MP) were observed to greatly enhance the CL intensity. It is suggested that the CL enhancement might be due to the fact that thiol-containing compounds could facilitate the electron transfer process under the catalysis of Pt nanoparticles and accelerate the generation of OH and O2? radicals, leading to the strong CL. 相似文献
976.
Based on zinc blende and wurtzite structures of experimental ZnTe and CdTe nanocrystals, ZnmCdnXy (X = Te, Se and S) clusters were investigated using DFT/B3LYP/LANL2DZ. From analyses of their characters of conformations,
HOMO–LUMO gaps, Raman and absorption spectra, Mulliken charges and WBI (Wiberg Bond Index) values, we have discovered that
ZnmCdnTey, ZnmCdnSey and ZnmCdnSy molecules had similar characters. In this paper, characters of ZnmCdnTey were investigated in detail. First, we have found that HOMO–LUMO gaps, Raman spectra, absorption spectra, bond lengths and
Mulliken charges of doping Zn2CdTe3, ZnCd2Te3, Zn3CdTe4, Zn2Cd2Te4 and ZnCd3Te4 structures were in the scope of corresponding naked ZnTe and CdTe clusters. These characters of doping ZnmCdnTey molecules show that their stabilities are good. Second, comparing with ZnTe structures, the wavelengths of the absorption
peaks of doping ZnmCdnTey clusters shift to red in water environment. Moreover, with increasing of the number of Cd atom, their wavelengths of the
absorption peaks gradually shift to red. This conclusion is consistent with the experimental fact. Third, Raman spectra of
pure ZnTe clusters have higher frequencies than corresponding naked CdTe structures. As for doping molecules, the frequencies
of their Raman spectra gradually shift to low frequencies with increasing of Cd atoms’ number. 相似文献
977.
A novel poly(aniline‐co‐o‐aminophenol) (PAOA)/mesoporous silica SBA‐15 nanocomposite was synthesized and investigated for adsorption of Hg (II) from aqueous solutions of wide pH range. A chemical oxidation method was employed for polymerization of aniline and o‐aminophenol on an ordered SBA‐15 template to obtain a significantly enlarged BET surface area of the adsorbent. Efficiency study revealed that the PAOA/SBA‐15 could reach a maximum Hg (II) adsorption capacity of over 400 mg/g. Kinetic study showed that the Hg (II) adsorption by the PAOA/SBA‐15 fitted a pseudo‐second‐order kinetic model, indicating that the mercury adsorption process was predominantly controlled by chemical process. The results of this study also proved that the adsorbed Hg (II) could be effectively desorbed from the PAOA/SBA‐15 in 0.1M HCl and 5% sulfocarbonide solutions. Associated adsorption mechanism was also investigated by means of Fourier transform infrared (FTIR) and X‐ray photoelectron spectroscopy (XPS) techniques. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
978.
Zhang Y Zhang H Cui W Chen H 《Journal of the American Society for Mass Spectrometry》2011,22(9):1610-1621
Our previous study showed that selenamide reagents such as ebselen and N-(phenylseleno)phthalimide (NPSP) can be used for selective and rapid derivatization of protein/peptide thiols in high conversion
yield. This paper reports the systematic investigation of MS/MS dissociation behaviors of selenamide-derivatized peptide ions
upon collision induced dissociation (CID) and electron transfer dissociation (ETD). In the positive ion mode, derivatized
peptide ions exhibit tag-dependent CID dissociation pathways. For instance, ebselen-derivatized peptide ions preferentially
undergo Se–S bond cleavage upon CID to produce a characteristic fragment ion, the protonated ebselen (m/z 276), which allows selective identification of thiol peptides from protein digest as well as selective detection of thiol
proteins from protein mixture using precursor ion scan (PIS). In contrast, NPSP-derivatized peptide ions retain their phenylselenenyl
tags during CID, which is useful in sequencing peptides and locating cysteine residues. In the negative ion CID mode, both
types of tags are preferentially lost via the Se–S cleavage, analogous to the S–S bond cleavage during CID of disulfide-containing
peptide anions. In consideration of the convenience in preparing selenamide-derivatized peptides and the similarity of Se–S
of the tag to the S–S bond, we also examined ETD of the derivatized peptide ions to probe the mechanism for electron-based
ion dissociation. Interestingly, facile cleavage of Se–S bond occurs to the peptide ions carrying either protons or alkali
metal ions, while backbone cleavage to form c/z ions is severely inhibited. These results are in agreement with the Utah-Washington mechanism proposed for depicting electron-based
ion dissociation processes. 相似文献
979.
We report a microfibre absorption sensor by using a 900 nm diameter silica microfibre embedded in a 125 μm wide microchannel with a detection length of 2.5 cm. Investigated by measuring the absorbance of methylene blue (MB), the sensor shows a detection limit down to 50 pM with excellent reversibility in a concentration range of 0-5 nM. The sensor has also been applied to bovine serum albumin (BSA) measurement, with a detection limit of 10 fg mL(-1). In addition, the sample volume requirement is merely 500 nL with a probing light power of about 150 nW, which is very promising for safe detection of single or a few molecules of biological specimens. 相似文献
980.
Ding ZG Li MG Ren J Zhao JY Huang R Wang QZ Cui XL Zhu HJ Wen ML 《Organic & biomolecular chemistry》2011,9(8):2771-2776
Phenazinolins A-E (1-5), which possess a carbon skeleton unique to diphenazines (the azabicyclo[3.3.1]nonadienol moiety in 1-3 and the oxabicyclo[3.3.1]nonadienol moiety in 4 and 5), were isolated from tin mine tailings-derived Streptomyces diastaticus YIM DT26, with 1-3 exhibited appreciable cytotoxicity and antibiotic effects. 相似文献