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111.
María Jesús Almendral Angel Alonso María José Porras Marco A. García Yolanda Curto 《Mikrochimica acta》2004,147(1-2):117-123
A flow-injection procedure for the determination of iron(III) in water is described. The procedure is based on the formation of an ion pair between the tetraphenylarsonium (Ph4As+) (TPA) or tetrabutylammonium (But4N+) (TBA) cations and the tetrathiocyanatoferrate(III) complex (TTF). This ion pair is extracted with chloroform, and the absorbance of the organic phase is measured at 503nm (for Ph4As+) or 475nm (for But4N+). Iron concentrations higher than 0.9×10–6molL–1 (50µgL–1) can be detected in the first case, with a relative standard deviation of 1.9% (n=12), a linear application rangeof between 1.34 and 54.0×10–6molL–1 (75–3015µgL–1), and a sampling frequency of 30h–1. For the ion pair with But4N+, the detection limit is 0.52×10–6molL–1 (29µgL–1), with a relative standard deviation of 1.6% and a linear application range between 0.73 and 54.0×10–6molL–1. Under the proposed working conditions, only Pd(IV), Cu(II) and Bi(III) interfere. With the application of the merging zones technique, considerable amounts of organic reagent can be saved. The TBA method was applied to the analysis of iron(III) in tap and industrial waste waters. 相似文献
112.
William J. Ramsay Jonathan A. Foster Katharine L. Moore Tanya K. Ronson Rapha?l J. Mirgalet David A. Jefferson Jonathan R. Nitschke 《Chemical science》2015,6(12):7326-7331
The incorporation of an N-heterocyclic carbene (NHC) moiety into a self-assembled MII4L6 cage framework required the NHC first to be metallated with gold(i). Bimetallic cages could then be constructed using zinc(ii) and cadmium(ii) templates, showing weak luminescence. The cages were destroyed by the addition of further gold(i) in the form of AuI(2,4,6-trimethoxybenzonitrile)2SbF6, which caused the reversibly-formed cages to disassemble and controllably release the AuI-NHC subcomponent into solution. This release in turn induced the growth of gold nanoparticles. The rate of dianiline release could be tuned by capsule design or through the addition of chemical stimuli, with different release profiles giving rise to different nanoparticle morphologies. 相似文献
113.
Selective Endo and Exo Binding of Mono‐ and Ditopic Ligands to a Rhomboidal Diporphyrin Prism 下载免费PDF全文
Dr. Govindasamy Jayamurugan Derrick A. Roberts Dr. Tanya K. Ronson Prof. Jonathan R. Nitschke 《Angewandte Chemie (International ed. in English)》2015,54(26):7539-7543
Copper(I) can preferentially form heteroleptic complexes containing two phosphine and two nitrogen donors due to steric factors. This preference was employed to direct the self‐assembly of a porphyrin‐faced rhomboidal prism having two parallel tetrakis(4‐iminopyridyl)porphyrinatozinc(II) faces linked by eight 1,4‐bis(diphenylphosphino)benzene pillars. The coordination preferences of the CuI ions and geometries of the ligands come together to generate a slipped‐cofacial orientation of the porphyrinatozinc(II) faces. This orientation enables selective encapsulation of 3,3′‐bipyridine (bipy), which bridges the ZnII ions of the parallel porphyrins, whereas 4,4′‐bipy exhibits weaker external coordination to the porphyrin faces. Reaction with 2,2′‐bipy, by contrast, results in the displacement of the tetratopic porphyrin ligand and formation of [{(2,2′‐bipy)CuI}2(diphosphine)2]. The differing strengths of interactions of bipyridine isomers with the system allows for a hierarchy to be deciphered, whereby 4,4′‐bipy may be displaced by 3,3′‐bipy, which in turn is displaced by 2,2′‐bipy. 相似文献
114.
The present study aims at developing an extraction protocol for efficient ginsenoside recovery from cell suspensions of Panax quinquefolius and P. sikkimensis. Methanol (100%, 70% and 30%), water (40°C, 90°C), water-saturated butanol and butanol-saturated water were compared for their ultrasonication-assisted ginsenoside retrieval efficacy. HPLC and HP-TLC analysis revealed 100% methanol as the best solvent for maximum retrieval of Rb (diol) and Rg (triol) ginsenosides (P. quinquefolius: Rb: 0.189, Rg: 3.163 mg/g DW; P. sikkimensis: Rb: 0.245, Rg: 4.073 mg/g DW), followed by water (90°C). Methanolic solutions, especially 70%, proved to be significant retrievers of Rg1 (1.812 and 1.327 mg/g DW in P. quinquefolius and P. sikkimensis), with poor Re recovery (0.328 and 0.342 mg/g DW). Water-saturated butanol also led to significant ginsenoside extraction (72.4% of content extracted by methanol), selectively in P. quinquefolius, with a less than 50% of total content extracted by methanol, in P. sikkimensis. 相似文献
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117.
We present a modified London model suggested by Brandt [1–3] which introduces a finite vortex core size appropriate for isotropic superconductors in which the average internal field is less than approximately (1/4)H
c2. TheSR lineshape resulting from this model possesses a distinctive shape due to the magnetic penetration depth and the vortex core diameter (approximately equal to twice the coherence length ). However, for a given lineshape, there is a large range of values of and which produce nearly the same lineshape. Lineshape smearing caused by disorder in the vortex lattice increases uncertainty in values for and . If well-determined values of either (T) or (T) are not available from another technique, both of them can be determined bySR measurements alone if runs in more than one applied field at the same temperature are fit with and as shared parameters. We also present our method of estimating the degree of disorder in the vortex lattice. 相似文献
118.
I. Porras D. Matthew Feldmann Frederick W. King 《International journal of quantum chemistry》1999,71(6):455-463
Lower‐bound estimates for the ground‐state energy of the helium atom are determined using nonlinear programming techniques. Optimized lower bounds are determined for single‐particle, radially correlated, and general correlated wave functions. The local nature of the method employed makes it a very severe test of the accuracy of the wave function. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 71: 455–463, 1999 相似文献
119.
Dmitry A Butov Yuri N Pashkov Anna L Stepanenko Aleksandra I Choporova Tanya S Butova Dendev Batdelger Vichai Jirathitikal Aldar S Bourinbaiar Svetlana I Zaitzeva 《Journal of immune based therapies and vaccines》2011,9(1):3
Placebo-controlled, randomized, phase 2b trial was conducted in 34 adults comprising 18 first-diagnosed (52.9%), 6 relapsed (17.6%), and 10 MDR-TB (29.4%) cases to investigate the safety and efficacy of an oral immune adjunct (V5). The immunotherapy (N = 24) and placebo (N = 10) arms received once-daily tablet of V5 or placebo for one month in addition to conventional anti-TB therapy (ATT) administered under directly observed therapy (DOT). 相似文献
120.
Mimmo Iannelli Tanya Kostova Fabio Augusto Milner 《Numerical Methods for Partial Differential Equations》2009,25(4):918-930
In many applications of age‐ and size‐structured population models, there is an interest in obtaining good approximations of total population numbers rather than of their densities. Therefore, it is reasonable in such cases to solve numerically not the PDE model equations themselves, but rather their integral equivalents. For this purpose quadrature formulae are used in place of the integrals. Because quadratures can be designed with any order of accuracy, one can obtain numerical approximations of the solutions with very fast convergence. In this article, we present a general framework and a specific example of a fourth‐order method based on composite Newton‐Cotes quadratures for a size‐structured population model. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009 相似文献