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981.
Water-soluble CdTe quantum-dots (QDs) of different sizes and capped with mercaptosuccinic acid were prepared by the microwave irradiation method. The QDs can significantly enhance the chemiluminescence (CL) of the pyrogallol-H2O2 system. Those with a diameter of 3.8 nm produce the most intense CL. UV-vis, photoluminescence, and CL spectra were acquired in order to explore the effect. The results showed that the chromium(III) ion in the concentration range from 20 pM to 30 µM enhances CL, and this is exploited for its trace determination.The limit of detection (3σ) is 6 pM, with a relative standard deviation (n?=?11) of 1.7%. A continuous flow injection CL method was developed and applied to the determination of chromium(III) in tap water and lake water samples with satisfactory results. 相似文献
982.
A method for flow injection with chemiluminescence (CL) detection has been developed for the determination of proteins. It is based on the luminescence of the N-bromosuccinimide-fluorescein-protein system, where fluorescein is used as an energy transfer reagent in alkaline medium. The CL of the system is strongly enhanced by hexadecyl trimethyl ammonium bromide. Optimum conditions and possible mechanisms have been investigated. Under optimum experimental conditions, the linear range is from 0.4 to 40 µg·mL?1 for egg albumin, 0.2 to 20 µg·mL?1 for bovine serum albumin, and from 1 to 100 µg·mL?1 for bovine hemoglobin. The detection limits are 37, 62, and 240 ng·mL?1, respectively. 相似文献
983.
Ying Tang Chaomei Xiong Daonian Zhou Anhua Wei Wei Fu Yaling Cai Jinlan Ruan 《Chemistry of Natural Compounds》2010,46(2):209-211
A new flavonoid, 5,7-dihydroxy-2-(1-hydroxy-2,6-dimethoxy-4-oxo-cyclohex)-chromen-4-one (1), was isolated from the roots of Macrothelypteris torresiana (Gaud.) Ching. (Thelypteridaceae). The structure of the product was identified on the basis of detailed spectral analysis,
including X-ray structure analysis. 相似文献
984.
Zhi‐An He Guang‐Zhou Lu Lin‐Lin Zhu Yong‐Xue Wang Fu‐Lin Yan Ji‐Xia Zhang 《中国化学会会志》2010,57(2):256-259
Two new ent‐kaurane diterpenoids, taihangexcisoidesin C (1) and its acetonide, taihangexcisoidesin D (2), along with 9 known compounds were isolated from the leaves of Isodon excisoides. The structures of the new compounds were elucidated using 1D and 2D NMR spectroscopy analysis. Compounds 3‐6 and 8‐9 were tested for their antibacterial activity against Escherichia coli, Staphylococcus aureus, S. epidermidis and S. saprophyticus. Compound 6 showed inhibitory effects on Staphylococcus aureus, S. epidermidis and S. saprophyticus MIC values 32, 16 and 16 μg/mL, respectively. All of the compounds didn't show effects on Escherichia coli (MIC > 10 mg/mL). 相似文献
985.
In the course of synthesizing 3-demethyltylophorine (1) by Lewis acid catalyzed intramolecular Friedel-Crafts reaction starting from N-(3-hydroxy-2,6,7-trimethoxy-phenanthr-9-ylmethyl)-2-chloromethylpyrrolidine, two chlorinated phenanthrene derivatives N-(4,10-dichloro-3-hydroxy-2,6,7-trimethoxyphenanthr-9-ylmethyl)-2-chloromethylpyrrolidine (4) and N-(4-chloro-3-hydroxy-2,6,7-trimethoxyphenanthr-9-ylmethyl)-2-chloromethylpyrrolidine (5) were obtained. The structures of these compounds were determined by spectroscopic analysis. 相似文献
986.
FengHui Tian ChengBu Liu Dongju Zhang Aiping Fu Yunbo Duan Shuping Yuan Jimmy C. Yu 《Chemphyschem》2010,11(15):3269-3272
Plane‐wave‐based pseudopotential density functional theory (DFT) calculations are used to elucidate the origin of the high photocatalytic efficiency of carbonate‐doped TiO2. Two geometrically possible doping positions are considered, including interstitial and substitutional carbon atoms on Ti sites. From the optical absorption properties calculations, we believe that the formation of carbonates after doping with interstitial carbon atoms is crucial, whereas the contribution from the cationic doping on Ti sites is negligible. The carbonate species doped TiO2 exhibits excellent absorption in the visible‐light region of 400–800 nm, in good agreement with experimental observations. Electronic structure analysis shows that the carbonate species introduce an impurity state from Ti 3d below the conduction band. Excitations from the impurity state to the conduction band may be responsible for the high visible‐light activity of the carbon doped TiO2 materials. 相似文献
987.
A rapid and universal bacteria-counting approach using CdSe/ZnS/SiO2 composite nanoparticles as fluorescence probe 总被引:1,自引:0,他引:1
In this paper, a rapid, simple, and sensitive method was described for detection of the total bacterial count using SiO2-coated CdSe/ZnS quantum dots (QDs) as a fluorescence marker that covalently coupled with bacteria using glutaraldehyde as
the crosslinker. Highly luminescent CdSe/ZnS were prepared by applying cadmium oxide and zinc stearate as precursors instead
of pyrophoric organometallic precursors. A reverse-microemulsion technique was used to synthesize CdSe/ZnS/SiO2 composite nanoparticles with a SiO2 surface coating. Our results showed that CdSe/ZnS/SiO2 composite nanoparticles prepared with this method possessed highly luminescent, biologically functional, and monodispersive
characteristics, and could successfully be covalently conjugated with the bacteria. As a demonstration, it was found that
the method had higher sensitivity and could count bacteria in 3 × 102 CFU/mL, lower than the conventional plate counting and organic dye-based method. A linear relationship of the fluorescence
peak intensity (Y) and the total bacterial count (X) was established in the range of 3 × 102–107 CFU/mL using the equation Y = 374.82X − 938.27 (R = 0.99574). The results of the determination for the total count of bacteria in seven real samples were identical with the
conventional plate count method, and the standard deviation was satisfactory. 相似文献
988.
Jinmao You Yanyan Fu Zhiwei Sun Yourui Suo 《Analytical and bioanalytical chemistry》2010,396(7):2657-2666
2-(5-Benzoacridine)ethyl-p-toluenesulfonate (BAETS), a dual-sensitive probe, was reacted with bile acids in the presence of K2CO3 catalyst in dimethyl sulfoxide (DMSO) solvent to give BAETS–bile acid derivatives. Derivatives exhibited intense fluorescence
(FL) with an excitation maximum at λ
ex 270 nm and an emission maximum at λ
em 510 nm. MS analysis using APCI-MS indicated that derivatives had excellent APCI-MS ionizability with percentage ionization
δ values changing from 0 to 88.83% in aqueous acetonitrile and from 0 to 89.15% in aqueous methanol. The collision induced
dissociation spectra of m/z [M + H]+ contained specific fragment ions at m/z [M + H−H2O]+, [M + H−2H2O]+, [M + H−3H2O]+, 347.3, and 290.1. Repeatability was good for LC separation of BAETS–bile acid derivatives with aqueous acetonitrile as mobile
phase. The relative standard deviations (RSDs) of retention time and peak area at 6.6 nmol mL−1 levels with fluorescence detection (FL) were from 0.045 to 0.072% and from 2.16 to 2.73%, respectively. Excellent linear
responses were observed, with regression coefficients >0.9995. The FL detection limits (S/N = 3) were in the range of 18.0–36.1 fmol. The online APCI-MS detection limits are in the range of 500–790 fmol (at a signal-to-noise
ratio of 3). 相似文献
989.
Changqing Yi Cheuk-Wing Li Huayang Fu Mingliang Zhang Suijian Qi Ning-Bew Wong Shuit-Tong Lee Mengsu Yang 《Analytical and bioanalytical chemistry》2010,397(7):3143-3150
Patterning is of paramount importance in many areas of modern science and technology. As a good candidate for novel nanoscale optoelectronics and miniaturized molecule sensors, vertically aligned silicon nanowire (SiNW) with controllable location and orientation is highly desirable. In this study, we developed an effective procedure for the fabrication of vertically aligned SiNW arrays with micro-sized features by using single-step photolithography and silver nanoparticle-induced chemical etching at room temperature. We demonstrated that the vertically aligned SiNW arrays can be used as a platform for label-free DNA detection using surface-enhanced Raman spectroscopy (SERS), where the inherent “fingerprint” SERS spectra allows for the differentiation of closely related biospecies. Since the SiNW array patterns could be modified by simply varying the mask used in the photolithographic processing, it is expected that the methodology can be used to fabricate label-free DNA microarrays and may be applicable to tissue engineering, which aims to create living tissue substitutes from cells seeded onto 3D scaffolds. Figure 1
Schematic illustration of fabrication procedures of SiNWs patterns 相似文献
990.
Ming-Lai Fu Norma L. Rangel Richard D. Adams Jorge M. Seminario 《Journal of Cluster Science》2010,21(4):867-878