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51.
Dawei Jiang Lei Cheng Yudong Xue Chao Chen Chaochao Wang Guoliang Yang An Xu Youjun Yang Yun Gao Weian Zhang 《Chemical science》2020,11(33):8785
The frontier of nitric oxide biology has gradually shifted from mechanism elucidation to biomanipulation, e.g. cell-proliferation promotion, cell-apoptosis induction, and lifespan modulation. This warrants biocompatible nitric oxide (NO) donating materials, whose NO release is not only controlled by a bioorthogonal trigger, but also self-calibrated allowing real-time monitoring and hence an onset/offset of the NO release. Additionally, the dose of NO release should be facilely adjusted in a large dynamic range; flux and the dose are critical to the biological outcome of NO treatment. Via self-assembly of a PEGylated small-molecule NO donor, we developed novel NO-donating nanoparticles (PEG-NORM), which meet all the aforementioned criteria. We showcased that a low flux of NO induced cell proliferation, while a high flux induced cell oxidative stress and, ultimately, death. Notably, PEG-NORM was capable of efficiently modulating the lifespan of C. elegans. The average lifespan of C. elegans could be fine-tuned to be as short as 15.87 ± 0.29 days with a high dose of NO, or as long as 21.13 ± 0.41 days with a low dose of NO, compared to an average life-span of 18.87 ± 0.46 days. Thus, PEG-NORM has broad potential in cell manipulation and life-span modulation and could drive the advancement of NO biology and medicine.Schematic illustration of modulating the longevity of the C. elegans by PEG-NORM nanoparticles. 相似文献
52.
Xu W. B. Zhou Z. F. He P. S. Pan W.-P. 《Journal of Thermal Analysis and Calorimetry》2004,78(1):113-124
The Flory's gelation theory, non-equilibrium thermodynamic fluctuation theory and Avrami equation have been used to predict
the gel time t
g and the cure behavior of epoxy resin/organo-montmorillonite/diethylenetriamine intercalated nanocomposites at various temperatures
and organo-montmorillonite loadings. The theoretical prediction is in good agreement with the experimental results obtained
by dynamic torsional vibration method, and the results show that the addition of organo-montmorillonite reduces the gelation
time t
gand increases the rate of curing reaction, the value of k, and half-time of cure after gelation point t1/2 decreases with the increasing of cure temperature, and the value of n is ~2 at the lower temperatures (<60°C) and decreases to ~1.5 as the temperature increases, and the addition of organo-montmorillonite
decreases the apparent activation energy of the cure reaction before gelation point, but has no apparent effect on the apparent
activation energy of the cure reaction after gelation point. There is no special curing process required for the formation
of epoxy resin/organo-montmorillonite/diethylenetriamine intercalated nanocomposite.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
53.
Qian-Feng Zhang Yu-Jie Liu Richard D. Adams Alexander Rothenberger Dieter Fenske Wa-Hung Leung 《Journal of Cluster Science》2006,17(3):445-455
Treatment of tetracopper(I)-phosphonitocavitand [1·Cu4(μ-Cl)4(μ4-Cl)] (2) (1 = tetraphosphonitocavitand [rccc-2,8,14,20-tetrakis-(iso-butyl)-phosphonitocavitand (C44H48O8P4Ph4)]) with PhSeSiMe3 in THF at low temperature afforded a novel polyanionic cluster [pyH]6[(CuCl)9(μ3-SePh)5(μ4-SePh)] (4) as a major product along with a new tetracopper(I)-phosphonitocavitand (3) with a centered μ3-Cl. Molecular structure of anionic cluster in 4 consists of six PhSe− bridging ligands containing five μ3-SePh and one exceptional μ4-SePh bridging nine copper atoms, of which eight copper atoms have trigonal coordination geometry and the other has distorted
tetrahedral geometry.
Dedicated to Professor Han-Qin Liu on the occasion of his 70th birthday. 相似文献
54.
Hongyang Su Lanlan Chen Yizhen Chen Prof. Rui Si Yuting Wu Xiaonan Wu Dr. Zhigang Geng Prof. Wenhua Zhang Prof. Jie Zeng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20591-20596
Efforts have been devoted to achieving a highly efficient artificial synthesis of ammonia (NH3). Reported herein is a novel Fe-MoS2 catalyst with Fe atomically dispersed onto MoS2 nanosheets, imitating natural nitrogenase, to boost N2 electroreduction into NH3 at room temperature. The Fe-MoS2 nanosheets exhibited a faradic efficiency of 18.8 % with a yield rate of 8.63 μg mgcat.−1 h−1 for NH3 at −0.3 V versus the reversible hydrogen electrode. The mechanism study revealed that the electroreduction of N2 was promoted and the competing hydrogen evolution reaction was suppressed by decorating the edge sites of S in MoS2 with the atomically dispersed Fe, resulting in high catalytic performance for the electroreduction of N2 into NH3. This work provides new ideas for the design of catalysts for N2 electroreduction and strengthens the understanding about N2 activation over Mo-based catalysts. 相似文献
55.
Fu-Sheng S 《Talanta》1983,30(6):446-448
The conditions for the reaction between phenylarsenazo (PAA) (2-[(2-arsonophenyl)azoj-7-(phenylazo)-1, 8-dihydroxynaphthalene-3,6-disulphonic acid) and chromium(III) have been studied. A blue 1:1 complex is formed at pH 2.2 on heating the reactants at 100 degrees for 15 min. It has maximum absorption at 635 nm and is stable for at least 24 hr. The molar absorptivity is 3.3 x 10(4) 1.mole(-1).cm(-1). Beer's law is obeyed in the chromium concentration range 0-1.4 mug ml . The reaction has been successfully applied to determination of chromium in alloy steel. 相似文献
56.
《Tetrahedron: Asymmetry》2006,17(6):900-907
Recently prepared chiral amines have been used in the preparation of novel tridentate ligands based on an imidazole ring with an additional (hetero)ring. The synthesis was carried out by the reaction of chiral amines with suitable aldehydes (2-phenylimidazole-4-carbaldehyde, 2-hydroxybenzaldehyde or pyridine-2-carbaldehyde) under reductive conditions (H2/Pd or NaBH4). All ligands prepared showed strong hydrogen bonds in d6-DMSO solution, which resulted in hindered imidazole tautomerism. The observed hindered tautomerism was studied by 1H NMR spectroscopy. The structures of the prepared ligands were also confirmed by APCI mass spectroscopy. Both chiral amines and tridentate compounds have been applied as ligands in copper (II)-catalyzed nitroaldol reactions (Henry reaction). Various reaction conditions for the Henry reaction have been studied (influence of temperature, molar ratio, solvent or copper (II) precursors). The compounds prepared with the two imidazole rings showed fast reaction times and a reversal in enantioselectivity compared to other chiral amines. 相似文献
57.
The absorption spectrum of neodymium (III) (Nd3+ doped in poly(methyl methacrylate) was measured. The Nephlauxetic effect was found in the spectrum compared to other spectra of Nd3+ doped in various matrices. The experimental data used, Slater-Condon parameters (F2,F4,F6) and Lander parameter (ζ4f) were calculated by the Taylor series expansion based on the assumption that the energy separation between J-levels of the 4fn-configuration is a function of F2,F4,F6 and ζ4f. The Judd-Ofled intensity parameters (Ω2,Ω4,Ω6) were also calculated. Analysis of the Nephlauxetic effect and the parameters variation on the host matrices was carried out. 相似文献
58.
Li Shu-Min Miao Yan-Gang Zhou Zi-Fang Chen Ji Liu Yao-Yang 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,39(1):29-34
The first Born approximation is used to study the laser-assisted electron capture by a fast proton from a hydrogen atom. The laser modification on differential cross section peaks sharply in the forward direction. With the impact energy increasing, the change in integral cross section becomes notable. The more intense the laser, the greater the cross section is; the lower the frequency, the greater the cross section. 相似文献
59.
A Background and noise elimination method for quantitative calibration of near infrared spectra 总被引:1,自引:0,他引:1
Da Chen 《Analytica chimica acta》2004,511(1):37-45
A new hybrid algorithm is proposed to eliminate the varying background and noise simultaneously for multivariate calibration of near infrared (NIR) spectral signals. The method is based on the use of multi-resolution, which is one of the main advantages provided by wavelet transform. The signals are firstly split into different frequency components, which keep the same data points of the original signals. In conjunction with a modified uninformative variable elimination (mUVE) criterion, the new method can be used to remove the low-frequency varying background and the high-frequency noise simultaneously. The method is successfully applied to simulated spectral data set and experimental NIR spectral data, resulting in more parsimonious multivariate models with higher precision. In addition, the proposed strategy can be applied to other spectral signals as well. 相似文献
60.
A novel method for the simultaneous determination of phenolic compounds such as salicylic acid, resorcinol, phloroglucinol, p-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, and m-nitrophenol by high-performance liquid chromatography (HPLC) coupled with chemiluminescence (CL) detection was developed. The procedure was based on the chemiluminescent enhancement by phenolic compounds of the cerium(IV)-Tween 20 system in a sulfuric acid medium. The separation was carried out with an isocratic elution or with a gradient elution using a mixture of methanol and 1.5% acetic acid. For six phenolic compounds, the detection limits (3σ) were in the range 1.40-5.02 ng/ml and the relative standard deviations (n=11) for the determination of 0.1 μg/ml compounds were in the range 1.9-2.9%. The CL reaction was well compatible with the mobile phase of HPLC, no baseline drift often occurred in HPLC-CL detection was observed with a gradient elution. The method has been successfully applied to the determination of salicylic acid and resorcinol in Dermatitis Clear Tincture and p-hydroxybenzoic acid in apple juices. 相似文献