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121.
122.
Harry J. Whitlow Margaretha Andersson Mikael Hult Leif Persson Mohamed El Bouanani Mikael Östling Carina Zaring Nils Lundberg David D. Cohen Nick Dytlewski Peter N. Johnston Ian F. Bubb Scott R. Walker Erik Johanson Sture Hogmark P. Anders Ingemarsson 《Mikrochimica acta》1995,120(1-4):171-181
Recoil Spectrometry covers a group of techniques that are very similar to the well known Rutherford backscattering Spectrometry technique, but with the important difference that one measures the recoiling target atom rather than the projectile ion. This makes it possible to determine both the identity of the recoil and its depth of origin from its energy and velocity, using a suitable detector system. The incident ion is typically high-energy (30–100MeV)35C1,81Br or127I. Low concentrations of light elements such as C, O and N can be profiled in a heavy matrix such as Fe or GaAs. Here we present an overview of mass and energy dispersive recoil Spectrometry and illustrate its successful use in some typical applications. 相似文献
123.
Eva Hoffmann GyÖrgy Marko-Varga Istvan Csiky Jan Årke JÖnsoon 《International journal of environmental analytical chemistry》2013,93(1-3):161-171
Abstract A three-column ion chromatographic system for the removal of humic substances from natural waters, and subsequent on-line concentration and determination of nitrate and sulfate using non-suppressed ion chromatography is presented. Humic substances are removed using disposable adsorption columns packed with chemically bonded amine silica material. The sample is directly transfered to an ion exchange column where the anions are concentrated ca 10 times. After reversing the flow, the ions are transferred to a third column where they are separated and quantified. The detection limit is less than 1 mg L?1 of nitrate or sulfate in water containing 45mgL?1 of humic acid. 相似文献
124.
Elisabet Öberg Andreas Orthaber Marie-Pierre Santoni Fredrick Howard Sascha Ott 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):152-158
Abstract Attempts to utilize C-ethylenic phosphaalkenes in metathesis reactions are discussed. Unprecedented reactivity is observed where the vinylphosphaalkene undergoes the first step of the catalytic cycle and cross-metathesis with the phenylmethylene moiety of Grubbs 2nd generation catalyst. However, homo-metathesis reaction to form 1,6-diphosphahexa-1,3,5-triene is not observed, presumably due to steric constraints. 相似文献
125.
We report on the application of a simple and versatile antioxidant capacity assay for dietary polyphenols, vitamin C and vitamin
E utilizing the copper(II)-neocuproine (Cu(II)-Nc) reagent as the chromogenic oxidant, which we term the CUPRAC (cupric reducing
antioxidant capacity) method. It involves mixing the antioxidant solution (directly or after acid hydrolysis) with solutions
of CuCl2, neocuproine, and ammonium acetate at pH 7, and measuring the absorbance at 450 nm after 30 min. Slowly reacting antioxidants
required an incubation at 50 °C for 20 min for color development. The flavonoid glycosides were hydrolyzed to their corresponding
aglycones by refluxing in 1.2 M HCl-containing 50% MeOH for fully exhibiting their antioxidant potencies. Certain compounds
also needed incubation after acid hydrolysis for color development. The CUPRAC absorbances of mixture constituents were additive,
indicating lack of chemical deviations from Beer’s law. The CUPRAC antioxidant capacities of a wide range of polyphenolics
are reported in this work and compared to those found by ABTS/persulfate and Folin assays. The trolox-equivalent capacities
of the antioxidants were linearly correlated (r = 0.8) to those found by ABTS but not to those of Folin. The highest antioxidant capacities in the CUPRAC method were observed
for epicatechin gallate, epigallocatechin gallate, quercetin, fisetin, epigallocatechin, catechin, caffeic acid, epicatechin,
gallic acid, rutin, and chlorogenic acid in this order, in accordance with theoretical expectations. The experiences of other
CUPRAC users also are summarized.
Correspondence: Reşat Apak, Department of Chemistry, Faculty of Engineering, Istanbul University, Avcilar, TR-34320 Istanbul,
Turkey 相似文献
126.
127.
Aydin Tavman Serkan Ikiz A. Funda Bagcigil N. Yakut Özgür Seyyal Ak 《Russian Journal of Inorganic Chemistry》2010,55(2):215-222
2-Methyl-6-(5-H-methyl-chloro-nitro-1H-benzimidazol-2-yl)-phenols( HL
x
:x= 1-4)ligands and HL1 complexes with Fe(NO3)3, Cu(NO3)2, AgNO3, Zn(NO3)2 have been synthesized and characterized. The structures of the compounds were confirmed on the basis of elemental analysis,
molar conductivity, magnetic moment, FT-IR, 1H-and 13C-NMR. Antibacterial activity of the free ligands, their hydrochloride salts and the complexes were evaluated using the disk
diffusion method in dimethyl sulfoxide as well as the minimum inhibitory concentration dilution method, against nine bacteria.
While HL1 ligand has not any activity, it’s Ag(I) complex show antibacterial effect toward almost to all the bacteria. Zn(II) complex
has antibacterial effect on especially K. pneumoniae, S. epidermidis and S. aureus bacteria. 相似文献
128.
Fatma Başak Aydemir Akın Günay Figen Öztoprak Ş. İlker Birbil Pınar Yolum 《Journal of Global Optimization》2013,57(2):499-519
This paper proposes the use of multiagent cooperation for solving global optimization problems through the introduction of a new multiagent environment, MANGO. The strength of the environment lays in its flexible structure based on communicating software agents that attempt to solve a problem cooperatively. This structure allows the execution of a wide range of global optimization algorithms described as a set of interacting operations. At one extreme, MANGO welcomes an individual non-cooperating agent, which is basically the traditional way of solving a global optimization problem. At the other extreme, autonomous agents existing in the environment cooperate as they see fit during run time. We explain the development and communication tools provided in the environment as well as examples of agent realizations and cooperation scenarios. We also show how the multiagent structure is more effective than having a single nonlinear optimization algorithm with randomly selected initial points. 相似文献
129.
130.
Yusuf Öztürk Asım Egemen Yılmaz Evrim Çolak Ekmel Özbay 《Photonics and Nanostructures》2012,10(4):624-631
Planar metamaterials, which have incident to normal plane excitation unlike SRR-type structures and that are easily fabricated in multilayer form, have received great interest in recent years. In this paper, one-dimensional and polarization independent circular fishnet metamaterials and their equivalent discontinuous slab-pair modeling for tuning resonance frequencies are introduced. After the numerical and experimental demonstration of the inclusions, the standard retrieval characterization methods and the correspondent/related backward-wave propagation observation are realized in order to check the physical explanation mentioned in the paper. In addition, a detailed phase analysis is performed in order to demonstrate the application of the suggested structure as a phase compensator. 相似文献