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81.
Summary A continuous-flow method that combines on-line preconcentration and isolation with gas chromatography for the direct determination of vitamins D2 and D3 in oily solutions is reported. A silica gel column permits preconcentration and isolation of analytes from the vitamin D matrix, although some triglyceride (ca. 25%) is also retained. To overcome problems associated with the low volatility of triglycerides, their retained fraction is further transesterified with potassium methylate to fatty acid methyl esters after elution. The proposed method was applied to the determination of vitamin D in pharmaceutical preparations. 相似文献
82.
G. L. Kelley J. A. Wiley R. T. Bohm W. C. Wright H. H. Willard Florence Fenwick J. M. Kolthoff O. Tomicek H. Tusker W. Chlopin L. Kaufmann H. D. Newton J. L. Hughes K. Swoboda C. Gallego A. T. Etheridge Hammer Koch A. Fölsner K. Ries W. Singleton A. Kropf G. Misson W. Silberminz E. Roshkowa A. H. Low Julius Meyer O. Kropf S. G. Clarke G. E. F. Lundell J. I. Hoffman H. A. Bright A. Pawletta L. Pisarjewski P. Düllberg W. M. Hartmann 《Analytical and bioanalytical chemistry》1932,88(5-6):206-237
83.
84.
G. Gallego Ferrer M. Salmerón Sánchez J.L. Gómez Ribelles F.J. Romero Colomer 《European Polymer Journal》2007,43(8):3136-3145
The morphology of a series of hydrogels based on the interpenetration of poly(2-hydroxyethyl acrylate) and poly(ethyl acrylate) has been studied through transmission electron microscopy, TEM, atomic force microscopy, AFM, and dynamic-mechanical spectroscopy, DMA. For the TEM analysis phosphotungstic acid, PTA, was used as alternative selective staining agent to those commonly used. The good agreement between TEM and AFM images allowed us to confirm that the PTA technique is a very powerful tool for TEM analysis of these hydrogel systems. All the results show that the IPNs presented phase-separation with two kinds of microdomains: those preferentially with a hydrophilic nature and those with preferentially a hydrophobic one, of sizes that range from 30 nm to 100 nm. Each one of these domains is composed by smaller nanodomains of alternating hydrophobic and hydrophilic component ranging between 6 and 10 nm sizes, those preferentially with a hydrophilic nature having a larger proportion of hydrophilic nanodomains. The AFM images of the IPN with the highest PHEA mass fraction, xPHEA = 0.75, suggest that the hydrophilic phase is co-continuous in the material. A disperse hydrophilic phase is found when the PHEA mass fraction is reduced up to xPHEA = 0.38. This phase-separation is explained in terms of some characteristic parameters of the networks such as the mesh size and the number of units between cross-links. The morphology found makes the systems very attractive for cell adhesion substrates and for matrices of scaffolds in soft tissue engineering. 相似文献
85.
A micellar electrokinetic capillary chromatographic method is presented which enables quantification of dexamethasone, polymyxin B and trimethoprim in synthetic mixtures and pharmaceutical products. Separation was carried out at 25?°C and 30 kV, with 10 mmol L–1 borate–phosphate buffer adjusted to pH 8 as electrolyte, with 50 mmol L–1 sodium dodecyl sulfate. Under these conditions separations were performed in 10 min. The limits of detection and quantification were approximately 2 mg L–1 for each component, except for polymyxin B. The method was applied to different commercial formulations. 相似文献
86.
Santiago Gómez-Ruiz Beatriz Gallego Željko Žižak Evamarie Hey-Hawkins Zorica D. Juranić Goran N. Kaluđerović 《Polyhedron》2010
Four titanium(IV) carboxylate complexes [Ti(η5-C5H5)2(O2CCH2SMes)2] (1), [Ti(η5-C5H4Me)2(O2CCH2SMes)2] (2), [Ti(η5-C5H5)(η5-C5H4SiMe3)(O2CCH2SMes)2] (3) and [Ti(η5-C5Me5)(O2CCH2SMes)3] (4; Mes = 2,4,6-Me3C6H2) have been synthesised by the reaction of the corresponding titanium derivatives [Ti(η5-C5H5)2Cl2], [Ti(η5-C5H4Me)2Cl2], [Ti(η5-C5H5)(η5-C5H4SiMe3)Cl2] and [Ti(η5-C5Me5)Cl3] and two (for 1–3) or three (for 4) equivalents of mesitylthioacetic acid. Complexes 1–4 have been characterized by spectroscopic methods and the molecular structure of the complexes 1, 2 and 4 have been determined by X-ray diffraction studies. The cytotoxic activity of 1–4 was tested against tumor cell lines human adenocarcinoma HeLa, human myelogenous leukemia K562, human malignant melanoma Fem-x, and normal immunocompetent cells, that is peripheral blood mononuclear cells PBMC and compared with those of the reference complexes [Ti(η5-C5H5)2Cl2] (R1), [Ti(η5-C5H4Me)2Cl2] (R2), [Ti(η5-C5H5)(η5-C5H4SiMe3)Cl2] (R3) and cisplatin. In all cases, the cytotoxic activity of the carboxylate derivatives was higher than that of their corresponding dichloride analogues, indicating a positive effect of the carboxylato ligand on the final anticancer activity. Complexes 1–4 are more active against K562 (IC50 values from 72.2 to 87.9 μM) than against HeLa (IC50 values from 107.2 to 142.2 μM) and Fem-x cells (IC50 values from 90.2 to 191.4 μM). 相似文献
87.
Daniel Pellico Mar Gómez‐Gallego Prof. Pedro Ramírez‐López Dr. María José Mancheño Prof. Miguel A. Sierra Prof. M. Rosario Torres Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(5):1592-1600
A novel approach for the synthesis of macrocyclic bis‐β‐lactams based on the Cu‐catalyzed alkyne–azide cycloaddition (CuAAC) is reported. The procedure is general and allows access to a full range of diastereomerically or enantiomerically pure macrocyclic cavities in good yields. The incorporation of chiral oxazolidinone fragments at C3 in the β‐lactam rings allows the total enantiocontrol of the process. 相似文献
88.
García-Fernández A Díez J Manteca A Sánchez J García-Navas R Sierra BG Mollinedo F Gamasa MP Lastra E 《Dalton transactions (Cambridge, England : 2003)》2010,39(42):10186-10196
The synthesis and full characterization of new half-sandwich ruthenium(II) complexes containing κ(3)(N,N,N)-hydridotris(pyrazolyl)borate (κ(3)(N,N,N)-Tp) and the water-soluble phosphanes 1,3,5-triaza-7-phosphatricyclo[3.3.1.1(3,7)]decane (PTA) and 1-methyl-3,5-diaza-1-azonia-7-phosphatricyclo[3.3.1.1(3,7)]decane (1-CH(3)-PTA) has been explored. Single crystal X-ray diffraction analysis for complex [RuCl{κ(3)(N,N,N)-Tp}(PMe(2)Ph)(1-CH(3)-PTA)][CF(3)SO(3)]·2NCMe is also reported. DNA binding properties of the ruthenium complexes have been evaluated by mobility shift assay and MALDI-TOF mass spectrometry. The in vitro antitumor activity of these compounds was assessed by examining their ability to inhibit cell proliferation in a number of human cancer cell lines (NCI-H460, SF-268, MCF-7) and non-tumor human umbilical vein endothelial cells (HUVEC). Some of these new compounds show promising cytotoxic activity with IC(50) values in the low micromolar range, and display differential effects on cancer and normal cell growth. 相似文献
89.
90.
Epithelial cell lines from several tissues show a differential sensitivity to Pseudomonas aeruginosa adherence. A549 (lung), HepG2 (liver) and Caco-2 (colon) cells presented an adhesion index of about 3, 1.5 and 5 CFU/cell, respectively, whereas Mz-Ch cell lines (gallbladder cholangiocytes) presented adhesion indexes up to 35. These variations could be associated with the variable amount of sialic acid in cell surface glycoconjugates. Moreover, the presence of free sialic acid in culture media induces the secretion by P. aeruginosa of a sialidase which is able to hydrolyze glycoconjugate-linked sialic acid. As shown with A549 cells, this specific hydrolysis increases bacterial adhesion, probably by unmasking new binding sites onto the cell surface. 相似文献