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281.
282.
Constantinos K. Zacharis Paraskevas D. Tzanavaras Athanasios G. Vlessidis 《Journal of separation science》2013,36(11):1720-1725
In the present study, we propose the first HPLC method coupled to postcolumn derivatization for the determination of rimantadine in human urine samples. The analyte and amantadine (internal standard) were isocratically separated using an RP monolithic stationary phase (100 × 4.6 mm id) with a mobile phase consisting of CH3OH/phosphate buffer (25 mmol/L, pH 3.0) at a volume ratio of 50:50. Postcolumn derivatization involved on‐line reaction with o‐phthalaldehyde (20 mmol/L) and N‐acetyl‐cysteine (5 mmol/L) at alkaline medium (100 mmol/L borate pH 11.0). Spectrofluorimetric detection at λex/λem = 340/455 nm enabled the selective and sensitive determination of rimantadine in urine samples at a range of 50–500 ng/mL with an LOD of 5 ng/mL. Human urine samples were analyzed successfully after SPE using hydrophilic‐lipophilic balanced RP cartridges (30 mg/mL, Oasis HLB). Recoveries ranged between 89.7 and 102.7%. 相似文献
283.
Modular Molecules: Site‐Selective Metal Substitution,Photoreduction, and Chirality in Polyoxometalate Hybrids
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Michele Vonci Fateme Akhlaghi Bagherjeri Peter D. Hall Dr. Robert W. Gable Athanasios Zavras Prof. Richard A. J. O'Hair Yuping Liu Dr. Jie Zhang Dr. Matthew R. Field Dr. Matthew B. Taylor Prof. Johan Du Plessis Prof. Gary Bryant Prof. Mark Riley Dr. Lorenzo Sorace Pablo A. Aparicio Dr. Xavier López Prof. Josep M. Poblet Dr. Chris Ritchie Dr. Colette Boskovic 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(43):14102-14111
The first members of a promising new family of hybrid amino acid–polyoxometalates have emerged from a search for modular functional molecules. Incorporation of glycine (Gly) or norleucine (Nle) ligands into an yttrium‐tungstoarsenate structural backbone, followed by crystallization with p‐methylbenzylammonium (p‐MeBzNH3+) cations, affords (p‐MeBzNH3)6K2(GlyH)[AsIII4(YIIIWVI3)WVI44YIII4O159(Gly)8‐ (H2O)14] ? 47 H2O ( 1 ) and enantiomorphs (p‐MeBzNH3)15(NleH)3 [AsIII4(MoV2MoVI2)WVI44YIII4O160(Nle)9(H2O)11][AsIII4(MoVI2WVI2)‐ WVI44YIII4O160(Nle)9(H2O)11] (generically designated 2 : L ‐Nle, 2 a ; D ‐Nle, 2 b ). An intensive structural, spectroscopic, electrochemical, magnetochemical and theoretical investigation has allowed the elucidation of site‐selective metal substitution and photoreduction of the tetranuclear core of the hybrid polyanions. In the solid state, markedly different crystal packing is evident for the compounds, which indicates the role of noncovalent interactions involving the amino acid ligands. In solution, mass spectrometric and small‐angle X‐ray scattering studies confirm maintenance of the structure of the polyanions of 2 , while circular dichroism demonstrates that the chirality is also maintained. The combination of all of these features in a single modular family emphasizes the potential of such hybrid polyoxometalates to provide nanoscale molecular materials with tunable properties. 相似文献
284.
The experimental conditions for the determination of platinum, palladium and rhodium by graphite furnace atomic absorption spectrometry (GFAAS) are re-assessed. A certified material (BCR-723) was used as a working sample and analyzed using various extraction and atomization procedures in order to find the optimal experimental conditions that enable the quantitative and reproducible detection of platinum, palladium and rhodium in environmental matrices. Evidently, literature observations regarding the atomization conditions were proven fairly adequate. However, the provision of the optimum extraction conditions revealed several parameters that lie behind the reported uncertainties. The appropriate combination between extraction conditions and atomization programs afforded a considerable improvement in the recoveries and analytical features of platinum, palladium and rhodium determination with GFAAS. Cross-examination of the analytical data with various CRMs (certified reference materials) was used to validate the robustness of the method in heterogeneous matrices bearing different element levels. Under the optimum experimental conditions the method permits the determination at concentrations as low as (LOD(3S/N)) 1.9 ng g(-1), 0.45 ng g(-1) and 0.6 ng g(-1) for Pt, Pd and Rh, respectively affording recoveries in the range of 93-101%. The method was successfully applied to the assessment of Pt, Pd and Rh accumulation in real road dust and soil samples in Greece. 相似文献
285.
Papageorgiou DP Tserepi A Boudouvis AG Papathanasiou AG 《Journal of colloid and interface science》2012,368(1):592-598
The requirement for low operational voltage in electrowetting devices, met using thin dielectrics, is usually connected with serious material failure issues. Dielectric breakdown (visible as electrolysis) is frequently evident slightly beyond the onset of the contact angle saturation. Here, plasma-enhanced chemical vapor deposition (PECVD) is used to deposit thin fluorocarbon films prior to the spin-coating of Teflon® amorphous fluoropolymer. The resulting multilayered hydrophobic top coating improves the electrowetting performance of the stack, by showing high resistance to dielectric breakdown at high applied voltages and for continuous long term application of DC and AC voltage. Leakage current measurements during electrowetting experiments with the proposed composite coating showed that current remains fairly constant at consecutive electrowetting tests in contrast to plain Teflon® coating in which material degradation is evident by a progressive increase in the leakage current after multiple electrowetting tests. Since the proposed composite coating demonstrates increased resistance to material failure and to dielectric breakdown even at thin configurations, its integration in electrowetting devices may impact their reliability, robustness, and lifetime. 相似文献
286.
BOUND STATES FOR A CLASS OF QUASILINEAR SCALAR FIELD EQUATIONS WITH POTENTIALS VANISHING AT INFINITY
Athanasios N. Lyberopoulos 《数学物理学报(B辑英文版)》2012,32(1)
We study the existence and non-existence of bound states (i.e.,solutions in W1,p(RN)) for a class of quasilinear scalar field equations of the form -Apμ + v(x)|u|p-2u =a(x)|u|q-2u, x ∈ RN, 1 < p < N,wh... 相似文献
287.
[reaction: see text] Simple, rapid, and efficient methods for P(1)' diversification of phosphinic peptides have been developed, employing alkylation and Knoevenagel-type condensation reactions with active methylene phosphinic scaffolds, thus leading to a wide variety of diversified phosphinic and dehydrophosphinic peptides. 相似文献
288.
Synthesis of oxadiazoloquinoxaline,oxathiadiazoloquinoxaline and oxadiazolobenzothiazine derivatives
Konstantina C. Fylaktakidou Konstantinos E. Litinas Athanasios Saragliadis Spyros G. Adamopoulos Demetrios N. Nicolaides 《Journal of heterocyclic chemistry》2006,43(3):579-583
289.
An efficient four-step synthetic strategy able to fully discriminate hydroxyphosphinyl and carboxylic groups of Fmoc-phosphinic building blocks and related analogues has been developed. The proposed method applies selective acidic removal of the phenacyl (Pac) group from the hydroxyphosphinyl functionality and protection by the 1-adamantyl (Ad) group. Reductive removal of the Pac group from the carboxylic functionality leads to Fmoc-protected phosphinic pseudodipeptidic units suitable for phosphinic peptide and library development using solid-phase peptide synthesis (SPPS). 相似文献
290.
Konstantina Tsaousi Athanasios A. Koutinas Argyro Bekatorou Paul Loukatos 《Applied biochemistry and biotechnology》2010,162(2):594-606
Low-cost dried yeasts immobilized on delignified brewers' spent grains for use in wine making and brewing were produced by
simple thermal drying techniques. To optimize the thermal drying process, vacuum and air stream conditions were examined.
Drying of thin layers of the biocatalysts was performed at low (30–38 °C) and high temperatures (40–70 °C). The fermentation
efficiency of the thermally dried biocatalysts was acceptable, with immobilized cells showing a significantly higher thermotolerance
compared with free cells. Immobilized cells dried at high temperatures presented slightly improved glucose fermentation efficiency
compared with the low-temperature dried biocatalysts. Gas chromatography–mass spectrometry analysis of aroma volatiles of
the fermented products revealed an increase of esters, lower higher alcohol formation, and significantly lower concentration
of carbonylic compounds. 相似文献