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121.
Liu JM Hu SR He XM Li XL Zhan FP Zeng LQ Li LD Zhu GH Huang XM 《Analytical and bioanalytical chemistry》2005,382(7):1507-1512
Silicon dioxide nano-particles, diameter 50 nm, containing morin (morin–SiO2) have been synthesized by the sol–gel method. They emit strong and stable room-temperature phosphorescence (SS-RTP) on filter paper as substrate, and bismuth can quench the intensity of the SS-RTP. On this basis a new morin–SiO2 solid-substrate room-temperature phosphorescence-quenching method has been established for determination of traces of bismuth. Reduction of phosphorescence intensity (Ip) is directly proportional to the concentration of bismuth in the working range 0.16–14.4 ag spot–1 (sample volume 0.40 L spot–1, corresponding to the concentration range 0.40–36.0 fg mL–1). The regression equation of the working curve is Ip=14.86+5.279×[Bi3+] (ag spot–1) (n=6, r=0.9982). The detection limit of this method is 0.026 ag spot–1 (corresponding to a concentration of 6.5×10–17 g mL–1).This sensitive, reproducible and accurate method has been used for successful analysis of real samples. 相似文献
122.
Photodynamic therapy (PDT) with topical aminolevulinic acid (ALA) has been shown in previous studies to improve psoriasis. However, topical ALA-PDT may not be practical for the treatment of extensive disease. In order to overcome this limitation we have explored the potential use of oral ALA administration in psoriatic patients. Twelve patients with plaque psoriasis received a single oral ALA dose of 10, 20 or 30 mg/kg followed by measurement of protoporphyrin IX (PpIX) fluorescence in the skin and circulating blood cells. Skin PpIX levels were determined over time after ALA administration by the quantification of the 635 nm PpIX emission peak with in vivo fluorescence spectroscopy under 442 nm laser excitation. Administration of ALA at 20 and 30 mg/kg induced preferential accumulation of PpIX in psoriatic as opposed to adjacent normal skin. Peak fluorescence intensity in psoriatic and normal skin occurred between 3 and 5 h after the administration of 20 and 30 mg/kg, respectively. Ratios of up to 10 for PpIX fluorescence between psoriatic versus normal skin were obtained at the 30 mg/kg dose of ALA. Visible PpIX fluorescence was also observed on normal facial skin, and nonspecific skin photosensitivity occurred only in patients who received the 20 or 30 mg/kg doses. PpIX fluorescence intensity was measured in circulating blood cells by flow cytometry. PpIX fluorescence was higher in monocytes and neutrophils as compared to CD4+ and CD8+ T lymphocytes. PpIX levels in these cells were higher in patients who received higher ALA doses and peaked between 4 and 8 h after administration of ALA. There was only a modest increase in PpIX levels in circulating CD4+ and CD8+ T lymphocytes. In conclusion oral administration of ALA induced preferential accumulation of PpIX in psoriatic plaques as compared to adjacent normal skin suggesting that PDT with oral ALA should be further explored for the treatment of psoriasis. 相似文献
123.
Single crystals of a neutral, microporous, laminated metal-organic framework (MOF)[Fe(pydc)(4,4'-bipy)]xH(2)O (1xH(2)O)(H(2)pydc = 2,5-dicarboxypyridine, 4,4'-bipy = 4,4'-bipyridine) were generated by hydrothermal synthesis, and its crystal structure was determined. 1xH(2)O retains the framework robustness to ca. 370 degrees C and is insoluble in common organic solvents. By soaking in MeOH and EtOH solutions, 1xH(2)O was transformed directly from the parent single crystals into single crystals of 1xMeOH or 1xEtOH, respectively. Meanwhile, 1xH(2)O shrank to the guest-free framework (h) or (v), respectively, under appropriate heating (up to 160 degrees C in N(2)) or vacuum treatment (10 mmHg) at room temperature. Compared to that of 1xH(2)O, the unit-cell volume of 1xEtOH slightly increases by 2.9%, whereas those of (h) or (v) are reduced by 8.2 and 6.6%, respectively. The anhydrous (v) was found to be highly chemically reactive, taking up ethanol vapor to furnish the solvated crystal structure of an 'expanded' framework 1xEtOH. In a mixture of ethanol-DMF or ethanol-benzene, a selective exchange process was observed, with only ethanol molecules exchanged into the structure due to the limited free size of the channels in the framework of. All the transformed crystals have also been characterized by X-ray single-crystal diffraction to understand the crystal-to-crystal transformation, which have different free volumes (6.5-20.4%). 相似文献
124.
Chaoyang Wang Fang Zeng Xinxing Liu Shuizhu Wu Ping Liu 《European Polymer Journal》2005,41(1):185-191
The complexation between poly(ethylene imine) (PEI) and poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) or AMPS copolymers was investigated with the relative excimer emission intensity IE/IM of a cationic probe 1-pyrenemethylamine hydrochloride (PyMeA · HCl), fluorescence nonradiative energy transfer (NRET) IPy/INp of naphthalene to pyrene labels, the fluorescence anisotropy r and IE/IM of pyrene labels. PEI was a hyperbranched weak polycation in acid solution, which formed complex with anionic polyelectrolytes due to the electrostatic attraction. The IE/IM of PyMeA · HCl probe decreased to zero, the intra-, intermolecular NRET IPy/INp and IE/IM of pyrene labels on the AMPS copolymers reached their maxima when χ was increased from 0 to 2.4, which was defined as the mole ratio of the amino group in PEI to the AMPS group in the polyanion. These facts indicated the formation of nonstoichiometric complex of the oppositely charged polyelectrolytes when χ = 2.4 at the concentration much lower than their overlap concentrations. The intermolecular aggregate appeared as indicated by an increase in the intermolecular IPy/INp and r with χ up to 2.4 due to neutralizing and hydrophobizing the polyelectrolytes and the bridging effect of the PEI chain bound on different polyanion chains. At high pH, PEI became a neutral polymer and did not bind with the AMPS anion to form the complex as illustrated by the constant value of r for the pyrene labels attached to the AMPS polyanion as that without addition of PEI. The amino group in PEI quenched pyrene and naphthalene emission, resulting a decrease in both INp and IPy. 相似文献
125.
Ruiyang Li Haiming Hua Yuejing Zeng Jin Yang Zhiqiang Chen Peng Zhang Jinbao Zhao 《Journal of Energy Chemistry》2022,(1):395-403
Poly(ethylene oxide)(PEO) is a classic matrix model for solid polymer electrolyte which can not only dissociate lithium-ions(Li+),but also can conduct Li+through segmental motion in long-range.However,the crystal aggregation state of PEO restricts the conduction of Li+ especially at room temperature.In this work,an amorphous polymer electrolyte with ethylene oxide(EO) and propylene oxide(PO) block structure(B-PEG@DMC) synthesized by the transesterification is firstly obtained,showing ... 相似文献
126.
Chemical Constituents from the Flowers of Carthamus tinctorius L. and Their Lung Protective Activity
Yanling Liu Mengna Wang Yangang Cao Mengnan Zeng Qinqin Zhang Yingjie Ren Xu Chen Chen He Xiling Fan Xiaoke Zheng Weisheng Feng 《Molecules (Basel, Switzerland)》2022,27(11)
A new flavonoid, saffloflavanside (1), a new sesquiterpene, safflomegastigside (2), and a new amide, saffloamide (3), together with twenty-two known compounds (4–25), were isolated from the flowers of Carthamus tinctorius L. Their structures were determined based on interpretation of their spectroscopic data and comparison with those reported in the literature. The protective effects against lipopolysaccharide (LPS)-stimulated damage on human normal lung epithelial (BEAS-2B) cells of the compounds were evaluated using MTT assay and cellular immunofluorescence assay. The results showed that compounds 2–3, 8–11, and 15–19 exhibited protective effects against LPS-induced damage to BEAS-2B cells. Moreover, compounds 2–3, 8–11, and 15–19 can significantly downregulate the level of nuclear translocation of NF-κB p-p65. In summary, this study revealed chemical constituents with lung protective activity from C. tinctorius, which may be developed as a drug for the treatment of lung injury. 相似文献
127.
Maoji Jiu (MJ) is a kind of medicinal wine that has been widely used by Chinese people for many years to nourish and promote blood circulation. The purpose of this study was to investigate the hematopoietic effect of MJ on the metabolism of blood deficient rats and to explore the underlying hematopoietic regulation mechanisms. Blood deficiency model rats were induced by subcutaneous injection of N-acetylphenylhydrazine (APH) and intraperitoneal injection of cyclophosphamide (CTX). The plasma metabolic fingerprints of blood deficiency model rats with and without MJ treatment were obtained by using metabonomics based on ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC–QTOF/MS). Orthogonal partial least squares-discriminant analysis (OPLS–DA) was used to evaluate the hematopoietic effect of MJ and identify potential biomarkers in the plasma of blood deficiency model rats. The levels of white blood cells (WBC), red blood cells (RBC) and hemoglobin (HGB) and the activity of antioxidant capacity showed a recovery trend to the control group after MJ treatment, while the dose of 10 mL/kg showed the best effect. In this study, thirteen potential biomarkers were identified, which were mainly related to seven metabolic pathways, including linoleic acid metabolism, d-glutamine and d-glutamate metabolism, alanine, aspartate and glutamate metabolism, tryptophan metabolism, pyrimidine metabolism, porphyrin and chlorophyll metabolism and arginine biosynthesis. Metabolomics was applied frequently to reflect the physiological and metabolic state of organisms comprehensively, indicating that the rapid plasma metabonomics may be a potentially powerful tool to reveal the efficacy and enriching blood mechanism of MJ. 相似文献
128.
In order to overcome the spectral interference of the conventional Fourier transform in the International Electrotechnical Commission framework, this paper introduces a Bregman-split-based compressive sensing (BSCS) method to estimate the Taylor–Fourier coefficients in a multi-frequency dynamic phasor model. Considering the DDC component estimation, this paper transforms the phasor problem into a compressive sensing model based on the regularity and sparsity of the dynamic harmonic signal distribution. It then derives an optimized hybrid regularization algorithm with the Bregman split method to reconstruct the dynamic phasor estimation. The accuracy of the model was verified by using the cross entropy to measure the distribution differences of values. Composite tests derived from the dynamic phasor test conditions were then used to verify the potentialities of the BSCS method. Simulation results show that the algorithm can alleviate the impact of dynamic signals on phasor estimation and significantly improve the estimation accuracy, which provides a theoretical basis for P-class phasor measurement units (PMUs). 相似文献
129.
130.
In this paper, the effects of a bistable potential function U(x)=-ax2/2+b|x|2γ/(2γ) on stochastic resonance (SR) is discussed. We investigate the effects of index γ on the performance of the SR system with fixed parameters a and b, and with fixed potential barriers, respectively. To measure the performance of the SR system in the presence of an aperiodic input, the bit error rate is employed, as is commonly used in binary communications. The numerical simulations strongly support the theoretical results. The goal of this investigation is to explore the effects of the shape of potential functions on SR and give a guidance of nonlinear systems in the application of information processing. 相似文献