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131.
High‐efficiency sample preparation approach to determine acrylamide levels in high‐fat foods 下载免费PDF全文
An improved sample preparation method was developed to enhance acrylamide recovery in high‐fat foods. Prior to concentration, distilled deionized water was added to protect acrylamide from degradation, resulting in a higher acrylamide recovery rate from fried potato chips. A Chrome‐Matrix C18 column (2.6 μm, 2.1 × 100 mm) was used for the first time to analyze acrylamide levels using ultra high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry, displaying good separation of acrylamide from interference. A solid‐phase extraction procedure was avoided, and an average recovery of >89.00% was achieved from different food matrices for three different acrylamide spiking levels. Good reproducibility was observed, with an intraday relative standard deviation of 0.04–2.38%, and an interday relative standard deviation of 2.34–3.26%. Thus, combining the improved sample preparation method for acrylamide analysis with the separation on a Chrome‐Matrix C18 column (2.6 μm, 2.1 × 100 mm) using ultra high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry is highly useful for analyzing acrylamide levels in complex food matrices. 相似文献
132.
Zeng X Xu X Wang X Zhao Z Zhao G Xu J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(3):860-864
The effects of gamma-irradiation on the air-annealed 10at.% Yb:Y(3)Al(5)O(12) (YAG) and air annealing on the gamma-irradiated 10at.% Yb:YAG have been studied by the difference absorption spectra before and after treatment. The gamma-irradiation and air annealing led to opposite changes of the absorption properties of the Yb:YAG crystal. After air annealing, the gamma-irradiation induced centers were totally removed and the concentration of Fe(3+) and Yb(3+) were lightly increased. For the first time, the gamma-irradiation induced valence changes between Yb(3+) and Yb(2+) ions in Yb:YAG crystals have been observed. 相似文献
133.
[equation: see text] An efficient one-pot route to unsymmetrical diorganyl selenides has been developed by ruthenium(III) chloride catalyzed reactions of dibenzyl or diphenyl diselenides with alkyl halides in the presence of zinc. Organic iodides, bromides, and activated chlorides underwent the reactions efficiently. Unreactive organic chlorides also underwent the same type of selenation with sodium bromide as the additive. 相似文献
134.
135.
Zhiqiang Cao Mingwan Leng Yirui Cao Xiaodan Gu Lei Fang 《Journal of polymer science. Part A, Polymer chemistry》2022,60(3):298-310
Persistence length is commonly used to quantitatively describe the chain rigidity of macromolecules, which represents an important structural parameter governing many physical properties of polymers. Although the mathematical models and experimental measurements on the chain rigidity of conventional single stranded polymers have been well explored and documented, those of the more rigid yet highly intriguing multiple stranded polymers, especially conjugated ladder polymers, are yet not well established. This article introduces the fundamental concepts on macromolecular chain rigidity, as well as the corresponding experimental methods, models, and simulations. Subsequently, representative examples of works done on the chain rigidity of nonladder conjugated polymers and conjugated ladder polymers are reviewed. Last but not least, it provides outlooks on the challenges with respect to the less-investigated chain rigidity of conjugated ladder polymers, including new models to describe and predict chain conformation, synthetic control on structural defects, and insights into the correlation of rigidity and applications. 相似文献
136.
Lexun Li Shuang Liu Chunjuan Zhang Zhenzhen Guo Shuxuan Shao Xiaodan Deng Prof. Qiaoling Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(69):e202202070
Due to its excellent programmability and biocompatibility, DNA molecule has unique advantages in cell surface engineering. Recent progresses provide a reliable and feasible way to engineer cell surfaces with diverse DNA molecules and DNA nanostructures. The abundant form of DNA nanostructures has greatly expanded the toolbox of DNA-based cell surface engineering and gave rise to a variety of novel and fascinating applications. In this review, we summarize recent advances in DNA-based cell surface engineering and its biological applications. We first introduce some widely used methods of immobilizing DNA molecules on cell surfaces and their application features. Then we discuss the approaches of employing DNA nanostructures and dynamic DNA nanotechnology as elements for creating functional cell surfaces. Finally, we review the extensive biological applications of DNA-based cell surface engineering and discuss the challenges and prospects of DNA-based cell surface engineering. 相似文献
138.
Xia Yang Leilei Xu Xiaodan Yu Wei Li Kexin Li Mingxin Huo Yihang Guo 《Colloids and surfaces. A, Physicochemical and engineering aspects》2008,320(1-3):61-67
Europium oxide/tantalum pentoxide (Eu2O3/Ta2O5) mixed oxides with different Eu2O3 dopings were prepared by a single-step sol–gel process via hydrolysis of tantalum pentachloride in the presence of europium nitrate. The products were in the amorphous and orthorhombic phase structures, respectively, based on the different calcination temperatures (200 and 500 °C). Composition, morphology, phase structure, Eu2O3-doping mode in the Ta2O5 matrix and optical absorption property of the products were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), field emission scanning electron microscopy (FESEM), X-ray diffraction patterns (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (UV–vis/DRS). The UV-light photocatalytic activity of the products was evaluated by degradation of aqueous rhodamine B (RB) and 4-nitrophenol (4-NP). The results showed that the photocatalytic activity of as-prepared Eu2O3/Ta2O5 was higher than that of pure Ta2O5 regardless of their phase structures. Among the tested samples, Eu2O3/Ta2O5 with 0.49% Eu loading obtained with 200 °C exhibited the highest activity to degradation of the above two model molecules. The reasons of this enhanced photocatalytic activity were discussed. 相似文献
139.
Huaihong Zhang Yu Sun Xiaodan Chen Qing Liang Baiwang Sun 《Journal of chemical crystallography》2011,41(5):715-720
Abstract
The title cobalt complex, [Co(C9H7N2O2)2H2O]H2O, has been synthesized by the reaction of ligand, 9-hydroxy-2-methyl-4H-pyrido[1,2-a]pyrimidine-4-one (HL), and cobalt nitrate. The synthesized complex was characterized by IR, elemental analysis (C, H and N), mass spectrometry and X-ray crystallography. The structure was solved in monoclinic, space group P21/c with a = 14.4584(13), b = 6.9385(8), c = 18.045(2) ?, β = 94.8440(10), V = 1803.8(3) ?3, Z = 4, and with R int = 0.034. The Co(II) complex, as shown by the single-crystal structure determination, existed as a mononuclear complex with distorted square-pyramidal geometry. The mental center was coordinated by two molecules from the bidentate ligand (HL) and an O atom from the coordinated water molecule. The intermolecular aromatic π–π stacking interactions generate discrete dimers. Furthermore, these discrete dimers were connected via O–H···O hydrogen bond in complex to form three-dimensional networks. At room temperature, the complex can emit blue luminescence at 430 nm in the solid state, while it about 42 nm blue-shifted in ethanol solution. Compared with free ligand, the luminescence was greatly intensified. 相似文献140.
Yanfei Yang Xiaodan Cao David W. Purkiss John F. Cannon Richard A. Bartsch 《Tetrahedron》2012,68(10):2233-2244
Di-ionizable calix[4]arene-1,3-crown-4 compounds locked in 1,3-alternate, cone, and partial-cone conformations are synthesized for evaluation in metal ion separations. The ionizable functions include carboxylic acid and N-(X)sulfonyl carboxamide groups in which the acidity is tuned by variation of the electron-withdrawing ability of X. Similar synthetic routes were employed for preparation of the cone and 1,3-alternate ligand series. A different preparative route utilizing protection and deprotection was required to obtain the partial-cone analogues. Ligand conformations were confirmed by their proton and/or carbon NMR spectra. X-ray diffraction verified an unusual 1,2-alternate conformation in the solid-state for one synthetic intermediate. Effects of ligand conformation and ionizable group variations on competitive solvent extractions of alkali and alkaline earth metal cations from aqueous solutions into chloroform were assessed. Single species solvent extractions of Hg2+ and Pb2+ were also performed. 相似文献