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101.
Elie Leopold 《Numerical Algorithms》2008,48(4):383-402
In this paper, we give some new extensions and some new applications of our results on the perturbation of coefficients and
the order of a general recurrence relation—for example we will give some new results for the asymptotic properties, for the
zeros and for the differential equations of the polynomials which satisfy the perturbed recurrence relation.
相似文献
102.
Silylation is usually carried out on γ-hydroxybutyrate (GHB) for its analysis by Gas Chromatography/Mass Spectrometry (GCMS) and requires potentially long incubation times before injection during which the derivatisation reagent and derivatives (such as trimethyl-silyl compounds) can hydrolyse. Moreover, alternative internal standards (IS) are often useful depending on sample matrices, extraction/purification procedures, commercial availability and price. This study evaluated the possibility of silylating GHB with an injection port derivatisation procedure using N-methyl-N-[tert-butyldimethyl-silyl]trifluoroacetimide (MTBSTFA) with 1% tert-butyldimethylchlorosilane (TBCS) as the derivatisation reagent, producing di-tert-butyldimethyl-silyl derivatives as a novel means of analyzing GHB. In parallel, trans-hydroxycrotonic acid (t-HCA) was investigated as a potential IS for GHB quantification. Analyses were carried out with a temperature programmable injector and the GHB(t-BDMS)(2) and t-HCA(t-BDMS)(2) derivatives were successfully produced, characterised and derivatisation conditions optimised. t-HCA behaved very similarly to GHB through the derivatisation processes and was used as the IS for the determination of urinary endogenous GHB concentrations in human subjects where the method showed a limit of detection of 0.049 μg mL(-1), a limit of quantification of 0.162 μg mL(-1), and a limit of confirmation of 1.33 μg mL(-1), suitable for toxicological GHB concentration determination. 相似文献
103.
Microfabricated microdisk electrode arrays (MDEAs) of 50 μm (5184 disks), 100 μm (1296 disks) and 250 μm (207 disks) (d/r=4; A= 0.1 cm2) were coated with poly(hydroxyethylmethacrylate)‐based hydrogel membranes and studied by electrochemical impedance spectroscopy (EIS) in 1.0 mM ferrocene monocarboxylic acid (FcCO2H). Equivalent circuit modeling showed an approximate three‐fold increase in solution resistance, Rsol, and an order of magnitude increase in charge transfer resistance, Rct, resulting from a reduction in apparent diffusivity of FcCO2H. Additionally, both resistive parameters decreased while the capacitance (Q) increased with decreasing microdisk diameter; consistent with an increase in effective electroactive area. The hydrogel layer did not compromise enhanced mass transport achieved by the MDEA and thus may be used to advantage in biosensors. 相似文献
104.
Considerable efforts are being made worldwide to replace in vivo assays with instrumental methods of analysis for the monitoring of marine biotoxins in shellfish. Analysis of these compounds by the preferred technique of liquid chromatography tandem mass spectrometry (LC-MS/MS) is challenged by matrix effects associated with the shellfish tissues. In methods validation, assessment of matrix interferences is imperative to ensure the validity and accuracy of results being produced. Matrix interferences for the analysis of okadaic acid (OA) and azaspiracid 1 (AZA1) were assessed using acidic methods on electrospray triple stage quadrupole (TSQ) and hybrid quadrupole time of flight (QToF) instruments by the use of matrix matched standards for different tissue types. Using an acidic method no matrix interference and suppression was observed on the TSQ for OA and AZA1 respectively, whilst the opposite was observed on the QToF; matrix enhancement for OA and no matrix interference for AZA1. The suppression of AZAs on the TSQ was found to be due to interfering compounds being carried over from previous injections. The degree of suppression is very much dependant on the tissue type ranging from 15 to 70%. Several strategies were evaluated to eliminate these interferences, including the partitioning of the extract with hexane, optimisation of the chromatographic method and the use of on-line SPE. Hexane clean up did not have any impact on matrix effects. The use of an alkaline method and a modified acidic method eliminated matrix suppression for AZA1 on the TSQ instrument while an on-line SPE method proved to be effective for matrix enhancement of OA on the QToF. 相似文献
105.
Elie B.?Megam Ngouonkadi Martial Kabong?Nono Victor Kamdoum?Tamba Hilaire B.?FotsinEmail author 《The European Physical Journal B - Condensed Matter and Complex Systems》2015,88(11):299
Diffusive electrical connections in neuronal networks are instantaneous, while excitatoryor inhibitory couplings through chemical synapses contain a transmission time-delay.Moreover, chemical synapses are nonlinear dynamical systems whose behavior can bedescribed by nonlinear differential equations. In this work, neuronal networks withdiffusive electrical couplings and time-delayed dynamic chemical couplings are considered.We investigate the effects of distributed time delays on phase synchronization of burstingneurons. We observe that in both excitatory and Inhibitory chemical connections, the phasesynchronization might be enhanced when time-delay is taken into account. This distributedtime delay can induce a variety of phase-coherent dynamical behaviors. We also study thecollective dynamics of network of bursting neurons. The network model presents theso-called Small-World property, encompassing neurons whose dynamics have two time scales(fast and slow time scales). The neuron parameters in such Small-World network, aresupposed to be slightly different such that, there may be synchronization of the bursting(slow) activity if the coupling strengths are large enough. Bounds for the criticalcoupling strengths to obtain burst synchronization in terms of the network structure aregiven. Our studies show that the network synchronizability is improved, as itsheterogeneity is reduced. The roles of synaptic parameters, more precisely those of thecoupling strengths and the network size are also investigated. 相似文献
106.
In Situ Synthesis of Self‐Assembled Gold Nanoparticles on Glass or Silicon Substrates through Reactive Inkjet Printing
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Mutalifu Abulikemu Eman Husni Da'as Dr. Hanna Haverinen Dr. Dongkyu Cha Dr. Mohammad Azad Malik Prof. Ghassan Elie Jabbour 《Angewandte Chemie (International ed. in English)》2014,53(2):420-423
A facile and low cost method for the synthesis of self‐assembled nanoparticles (NPs) with minimal size variation and chemical waste by using reactive inkjet printing was developed. Gold NPs with diameters as small as (8±2) nm can be made at low temperature (120 °C). The size of the resulting NPs can be readily controlled through the concentration of the gold precursor and oleylamine ink. The pure gold composition of the synthesized NPs was confirmed by energy‐dispersive X‐ray spectroscopy (EDXS) analysis. High‐resolution SEM (HRSEM) and TEM (HRTEM), and X‐ray diffraction revealed their size and face‐centered cubic (fcc) crystal structure, respectively. Owing to the high density of the NP film, UV/Vis spectroscopy showed a red shift in the intrinsic plasmonic resonance peak. We envision the extension of this approach to the synthesis of other nanomaterials and the production of tailored functional nanomaterials and devices. 相似文献
107.
Diethyl (E)-α-triphenylstannyl or (Z)-α-tri-n-butylstannyl α-alkenylphosphonates are conveniently and stereoselectively prepared using a “tin-Peterson-like” reaction. Protonolysis of the carbon-tin bond of α-tributylstannyl derivatives proved to be easy and stereospecific. 相似文献
108.
Poly(hydroxyethylmethacrylate)‐based hydrogel membranes were applied to microfabricated, microdisk electrode arrays (MDEAs) of 50 μm (5184 disks), 100 μm (1296 disks) and 250 μm (207 disks) (d/r=4; A= 0.1 cm2) and studied by cyclic voltammetry (CV) in 1.0 mM ferrocene monocarboxylic acid (FcCO2H). The membrane produced an order of magnitude decrease in current densities and a shift to quasi reversibility due to a decrease in the Dappt of FcCO2H, from 4.51×10?6 cm2 s?1 to 1.42×10?8 cm2 s?1, (2.18×10?8 cm2 s?1 from release experiments). The MDEA050 (comprising 50 μm disks) maintained its enhanced current density attributes confirming its value as an effective electrode for biosensors. Finite element modeling (FEM) simulations successfully replicated the voltammograms of the MDEAs. 相似文献
109.
110.
The threat of the accumulation of heavy metals in wastewater is increasing, due to their abilities to inflict damage to human health, especially in the past decade. The world’s environmental agencies are trying to issue several regulations that allow the management and control of random disposals of heavy metals. Scientific studies have heavily focused on finding suitable materials and techniques for the purification of wastewaters, but most solutions have been rejected due to cost-related issues. Several potential materials for this objective have been found and have been compared to determine the most suitable material for the purification process. Sawdust, among all the materials investigated, shows high potential and very promising results. Sawdust has been shown to have a good structure suitable for water purification processes. Parameters affecting the adsorption mechanism of heavy metals into sawdust have been studied and it has been shown that pH, contact time and several other parameters could play a major role in improving the adsorption process. The adsorption was found to follow the Langmuir or Freundlich isotherm and a pseudo second-order kinetic model, meaning that the type of adsorption was a chemisorption. Sawdust has major advantages to be considered and is one of the most promising materials to solve the wastewater problem. 相似文献