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101.
102.
Nurshazliana Othman Vuanghao Lim Muggundha Raoov Ramachandran Mohd Marsin Sanagi Sazlinda Kamaruzaman Yuichiro Hirota Norikazu Nishiyama Noorfatimah Yahaya 《Chromatographia》2017,80(10):1553-1562
A rapid, simple, and efficient method using ultrasound-assisted emulsification microextraction combined with dispersive micro-solid phase extraction (USAE-D-µ-SPE) was developed for detection and quantification of three azole antifungals in milk samples by high-performance liquid chromatography diode array detector. In this study, mesoporous carbon, COU-2, was used as sorbent in USAE-D-µ-SPE for the extraction and preconcentration of analytes. Several important experimental parameters, including type of deproteinized solvents, desorption time, type of extraction solvents, volume of extraction solvent, extraction time, emulsification time, sample pH, salt addition, and mass of COU-2 sorbent, were optimized using spiked milk samples. Under the optimum extraction and detection conditions, three azole antifungals, namely ketoconazole, clotrimazole, and miconazole, were determined within 20 min, with good linearity of matrix-matched calibration in the range of 0.5–5000.0 µg L?1 with coefficient of determination, r 2 ≥ 0.9943. The method showed limits of detection and limits of quantification of all analytes in the range of 0.15–3.0 and 0.5–10.0 µg L?1, respectively. Good repeatability with RSDs <15% (n = 3) and satisfactory relative recoveries (83.3–111.1%) were obtained for spiked azole antifungal drugs in milk. The results reveal that the developed USAE-D-µ-SPE method was a simple, rapid, efficient, environmentally friendly, and practicable method for the determination of azole antifungals in milk samples. 相似文献
103.
104.
We propose a dual focus optical head with a holographic optical element (HOE) which corrects spherical aberrations in order to read both 0.6 mm disks and 1.2 mm disks. The thin disks are read using transmitted light and the thick disks are read using +1st order diffracted light of the blazed HOE. The good quality of the focused spots and the focusing error signals was experimentally confirmed. No influence of unnecessary diffracted light was observed. 相似文献
105.
Nonnegative matrix factorization (NMF) is the problem of approximating a given nonnegative matrix by the product of two nonnegative matrices. The multiplicative updates proposed by Lee and Seung are widely used as efficient computational methods for NMF. However, the global convergence of these updates is not formally guaranteed because they are not defined for all pairs of nonnegative matrices. In this paper, we consider slightly modified versions of the original multiplicative updates and study their global convergence properties. The only difference between the modified updates and the original ones is that the former do not allow variables to take values less than a user-specified positive constant. Using Zangwill’s global convergence theorem, we prove that any sequence of solutions generated by either of those modified updates has at least one convergent subsequence and the limit of any convergent subsequence is a stationary point of the corresponding optimization problem. Furthermore, we propose algorithms based on the modified updates that always stop within a finite number of iterations. 相似文献
106.
Jing Xu Zheng-Shuai Bai Taka-aki Okamura Man-Sheng Chen Wei-Yin Sun Norikazu Ueyama 《Polyhedron》2009
Four new coordination polymers {[Ni(HL)(H2O)]·H2O}n (1), {[Co(HL)(H2O)]·H2O}n (2), {[Co(HL)]·4H2O}n (3) and {[Zn(HL)]·2H2O·0.5C2H5OH}n (4) [H3L = 5-(1H-imidazol-4-ylmethyl)aminoisophthalic acid] have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction analyses. Complexes 1 and 2 display (3, 3)-connected 2D network with (4, 82) topology. While 3 and 4 exhibit a binodal (3, 6)-connected 2D network with a Schläfli symbol (43)2(46, 66, 83). The complexes 1–4 show remarkable thermal stability and 4 exhibits blue fluorescence with maximum emission at 413 nm upon excitation at 362 nm in the solid state at room temperature. In addition, the magnetic measurements of 3 indicate that there are antiferromagnetic interactions between the neighboring Co(II) centers. 相似文献
107.
Transparent photochromic inorganic/organic hybrid gels involving the Chemically bonded spirobenzopyran moiety have been prepared by the sol–gel reactions using tetraethoxysilane, the silanol-terminated oligomeric poly(dimethylsiloxane), and spirobenzopyrans with the alcoxysilyl groups. 相似文献
108.
Fluoride complexation of element 104, rutherfordium 总被引:1,自引:0,他引:1
Haba H Tsukada K Asai M Toyoshima A Akiyama K Nishinaka I Hirata M Yaita T Ichikawa S Nagame Y Yasuda K Miyamoto Y Kaneko T Goto S Ono S Hirai T Kudo H Shigekawa M Shinohara A Oura Y Nakahara H Sueki K Kikunaga H Kinoshita N Tsuruga N Yokoyama A Sakama M Enomoto S Schädel M Brüchle W Kratz JV 《Journal of the American Chemical Society》2004,126(16):5219-5224
Fluoride complexation of element 104, rutherfordium (Rf), produced in the 248Cm(18O,5n)261Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchange chromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the 18O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effects on the fluoride complexation of Rf. 相似文献
109.
Sagara Y Mitsuya M Uchiyama M Ogino Y Kimura T Ohtake N Mase T 《Chemical & pharmaceutical bulletin》2005,53(4):437-440
Synthesis and structure-activity relationship of a new class of muscarinic M(3) selective antagonists were described. In the course of searching for a muscarinic M(3) antagonist with a structure distinct from those of the 2-(4,4-difluorocyclopentyl)-2-phenylacetamide derivatives, we identified a thiazole-4-carboxamide derivative (1) as a lead compound in our in-house chemical collection. Since this compound (1) showed relatively low binding affinity (K(i)=140 nM) for M(3) receptors in the human binding assays, we tried to improve its potency and selectivity for M(3) over M(1) and M(2) receptors by derivatization of 1 through a combinatorial approach. A solution-phase parallel synthesis effectively contributed to the optimization of each segment of 1. Thus, we have identified a cyclooctenylmethyl derivative (3e) and a cyclononenylmethyl derivative (3f) as representative M(3) selective antagonists in this class. 相似文献
110.
Synthesis of ordered mesoporous carbons with channel structure from an organic-organic nanocomposite 总被引:3,自引:0,他引:3
Tanaka S Nishiyama N Egashira Y Ueyama K 《Chemical communications (Cambridge, England)》2005,(16):2125-2127
Mesoporous carbons with ordered channel structure (COU-1) have been successfully fabricated via a direct carbonization of an organic-organic nanocomposite. 相似文献