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11.
Vassilios Karanassios Gary Horlick 《Spectrochimica Acta Part B: Atomic Spectroscopy》1989,44(12):1345-1360
A direct sample insertion (DSI) device has been developed for application to inductively coupled plasma-mass spectrometry (ICP-MS). In a DSI device for use with ICPs, the sample is placed into or onto a probe with subsequent introduction of the sample carrying probe, via the central tube of the ICP torch, into the plasma. A mechanical, stepper-motor driven, computer controlled DSI device and software support system has been designed and developed that can easily be attached to a commercial ICP-MS system (Perkin-Elmer/SClEX Elan). This system allows the direct introduction of microliter volumes of liquids and milligram quantities of powdered/solid samples into the ICP-MS with little or no sample pre-treatment. 相似文献
12.
Eleni E. Moushi Theocharis C. Stamatatos Vassilios Nastopoulos George Christou Anastasios J. Tasiopoulos 《Polyhedron》2009,28(9-10):1814-1817
The reaction of [Mn(O2CMe)2] · 4H2O with pdH2 (1,3-propanediol) or mpdH2 (2-methyl-1,3-propanediol) in the presence of NaN3 in MeCN/py (py = pyridine) results in the formation of two new one-dimensional coordination polymers composed of a [MnIII6MnII11(μ4-O)8(μ3-N3)4]25+ octahedral unit. The peripheral ligation is completed by pd2? (or mpd2?), acetate, pyridine and μ-1,3-N3? ligands. The latter bridges each Mn17 unit to its neighboring one, resulting in the formation of the two 1-D coordination polymers. Variable-temperature dc magnetic susceptibility studies indicate the existence of predominantly ferromagnetic interactions and a resulting giant ground state spin within the Mn17 units and intermolecular antiferromagnetic exchange interactions between the neighboring Mn17 units that result in diamagnetic ground spin states for both polymeric compounds. 相似文献
13.
(S)-7-Hydroxy-3-amino-3,4-dihydro-2H-1-benzopyran, a key synthetic intermediate towards the total synthesis of (+)-scyphostatin, has been prepared in >98% ee. Key synthetic steps were (i) the oxidative dearomatization of an l-tyrosine derived phenol, (ii) the transformation of the resulting p-quinol acetate to the corresponding resorcinol upon exposure to Thiele reaction conditions and, (iii) the direct formation of the benzopyran ring upon treatment of an N-Boc protected 4-(2-acetoxybenzyl)oxazolidin-2-one with sodium methoxide. 相似文献
14.
George Cordoyiannis Patricia Losada-Pérez Chandra Shekhar Pati Tripathi Brigita Rožič Uroš Tkalec Vassilios Tzitzios 《Liquid crystals》2013,40(11):1419-1426
The phase transition behaviour of the chiral liquid crystal CE6 doped with spherical surface-functionalised CdSe nanoparticles has been examined by means of high-resolution adiabatic scanning calorimetry and polarising microscopy. The addition of nanoparticles results in an essentially stabilised blue phase III. The phase diagram is displayed upon heating and cooling and the enthalpy changes involved in the conversion between the blue phases are determined. The dispersion of functionalised nanoparticles is prominent for the stabilisation of blue phase III, which is potentially useful for applications, especially if applied on liquid crystals that exhibit blue phases close to room temperature. 相似文献
15.
Sotirios Zarogiannis Vassilios Liakopoulos Chrissi Hatzoglou Konstantinos Vogiatzidis Marios Salmas Ioannis Stefanidis Konstantinos Gourgoulianis Paschalis Adam Molyvdas Spiros Lafis 《Analytical sciences》2007,23(5):593-595
This article reports on the development of a simple and cost-effective bioassay for the detection of biotin in urine and serum, based on the very selective binding of avidin and biotin. Avidin was allowed to react without isolating it from egg white. Egg white was treated with the dye HABA, which binds to avidin. Upon subsequent treatment with biotin, HABA is released due to the high affinity of biotin to avidin. The amount of HABA released is proportional to the amount of biotin used. 相似文献
16.
Vassilios Fessatidis Norman J.M. Horing 《Physica E: Low-dimensional Systems and Nanostructures》2005,27(4):487-494
We examine the collective mode spectrum for a double quantum-wire system embedded in semi-infinite polar medium, taking account of the role of optical phonons in interaction with the double quantum-wire plasmons and bulk/surface plasmons. The collective mode frequencies are exhibited as functions of qx (wavenumber parallel to the wires) and as functions of z0 (distance of first wire from the interface). We also find that the region of drift instability of the collective modes is split into two disjoint regions of instability by the optical phonons, with a region of stability between them. 相似文献
17.
Monomeric alkannin and shikonin (A/S) are potent pharmaceutical substances with a wide spectrum of biological activity and comprise the active ingredients for several pharmaceutical preparations. Therefore, the determination of the impurities, degradation products or byproducts in alkannin and shikonin samples is of great importance. Oligomeric alkannin and shikonin are formed during biosynthesis of these bioactive secondary metabolites in Boraginaceaous root plants, during tissue culture production of A/S, during alkaline hydrolysis of A/S esters and also thermal treatment of A/S. In the present study, a dimeric alkannin/shikonin compound was isolated by size exclusion chromatography from alkannin and shikonin commercial samples and its structure was determined by one- and two-dimensional NMR spectroscopy. The structure of the most abundant oligomeric species in these samples, a dimeric naphthoquinone, was established for the fi rst time, indicating that coupling of the side chain of one naphthoquinone unit with the aromatic ring of a second naphthoquinone leads to dimer formation. This type of coupling allows further oligomerization by leaving one isohexenyl side chain available at the second monomer unit. 相似文献
18.
Tsachouridis Vassilios A.; Kouvaritakis Basil 《IMA Journal of Mathematical Control and Information》2005,22(4):517-540
** Email: vassilios.tsachouridis{at}ieee.org*** Email: basil.kouvaritakis{at}eng.ox.ac.uk Algebraic quadratic equations are a special case of a singlegeneralized algebraic quadratic matrix equation (GQME). Hence,the importance of that equation in science and engineering isevident. This paper focus on the study of solutions of thatGQME and a unified framework for the characterization and identificationof solutions at infinity and of finite solutions of generalquadratic algebraic matrix equations is presented. The analysisis based on the concept of homogeneous projective transformationfor general polynomial systems (Morgan, 1986). In addition,a numerical error analysis for the computed solutions is providedfor the assessment of numerical accuracy, stability and conditioningof the computed solutions. The proposed framework is independentof any numerical method and therefore it can be used along withvarious possible numerical methods for the GQME solution, especiallymatrix flow-based algorithms (Chu, 1994) (e.g. continuation/homotopy,Morgan, 1989). 相似文献
19.
20.
Vassilios Yannopapas 《Optics Communications》2010,283(8):1647-1649
It is shown that the Kerr nonlinearity of a two-level atom placed in the vicinity of a two-dimensional array of metal-coated silica nanoparticles can be greatly enhanced due to quenching of both radiative and non-radiative spontaneous-emission paths for frequencies near the surface plasmon resonances. The spontaneous emission rate is calculated by rigorous electrodynamic calculations of the electric-field Green’s tensor. The Kerr susceptibility can be enhanced by two orders of magnitude even for large detunings heralding, this way, the observation of nonlinear phenomena for moderate radiation intensities. 相似文献