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1.
Priya Jaiswal Vijaykumar Ijeri Ashwini Srivastava 《Journal of inclusion phenomena and macrocyclic chemistry》2004,49(3-4):219-224
This paper is a report on the complexation studies of silverions with certain water soluble crown ethers viz., 15-crown-5,18-crown-6, cyclam, diaza 15-crown-5 and certain water insolublecrown ethers viz., benzo 15-crown-5, dibenzodiaza 15-crown-4,dibenzyldiaza 18-crown-6 in some nonionic surfactants viz.,polyoxyethylated alkyl phenol (TX 100), polyoxyethylene (20)sorbiton monolaurate (Tween 20), polyoxyethylene (20) sorbitonmonoleate (Tween 80) and polyoxyethylated glyco monolaurylether (Brij 35) by potentiometry. In addition, conductometry wasalso used to study the complexation of oxa crown ethers to comparethe results obtained by potentiometry, which were found to be ingood agreement with each other. The complexation studies indicate1:1 complex formation between the silver ion and macrocycle, thelogML n+ values being in the range 1 to 9. 相似文献
2.
The feasibility of fabricating copper-sensitive chemically modified electrodes (CMEs) for trace analysis in aqueous and in
40% (v/v) ethanol-water media was investigated. Carbon paste electrodes modified with crown ethers were constructed by mixing
the crown ethers into a graphite powder-paraffin oil matrix. The electrodes so formed were able to bind Cu(II) ions chemically
and gave better voltammetric responses than the unmodified ones. The crown ethers studied and compared were 15-crown-5, benzo-15-crown-5
and dibenzo-18-crown-6. With a 3% benzo-15-crown-5 CME, Cu(II) could be quantified at sub-ppm levels by differential pulse
voltammetry with a detection limit of 0.05 ppm. By differential pulse anodic stripping voltammetry Cu(II) could be quantified
over the range 1 to 100 ppb. Interference from metal ions like Ni(II), Co(II), Mn(II), Fe(II), etc. have also been studied.
The method was successfully applied to artificial as well as commercial samples of alcoholic beverages.
Received: 12 January 2000 / Revised: 14 March 2000 / Accepted: 16 March 2000 相似文献
3.
Spatial and temporal electrochemical control of singlet oxygen production and decay in photosensitized experiments 总被引:1,自引:0,他引:1
Ijeri VS Daasbjerg K Ogilby PR Poulsen L 《Langmuir : the ACS journal of surfaces and colloids》2008,24(3):1070-1079
Active spatial and temporal modulation of domains of singlet oxygen activity is demonstrated using electrochemical tools. Using singlet oxygen microscopy in photosensitized experiments, it is shown that singlet oxygen concentrations around an ultramicroelectrode can be controlled by applying a bias voltage to the electrode. Two phenomena that can be exploited separately or collectively are examined: (1) the singlet oxygen concentration can be altered by local oxidation or reduction of the photosensitizer, which is the precursor to singlet oxygen, and (2) the reduction of oxygen to produce the superoxide anion which, among other things, is an effective singlet oxygen quencher, results in a local decrease in the concentration of singlet oxygen around the electrode. Both of these phenomena depend significantly on the diffusion of molecules along concentration gradients established by the biased electrode. The results reported herein demonstrate that one can indeed exert local electrochemical control and readily manipulate the population of singlet oxygen produced in a photosensitized process. 相似文献
4.
EP Sheretov VS Gurov MV Dubkov OV Korneeva 《Rapid communications in mass spectrometry : RCM》1999,13(16):1699-1702
In this article we compare the classical monopole mass filter of von Zahn and the monopole mass filter with a hyperbolic V-shaped electrode. The experimental results and those of computer simulation for both mass spectrometers are presented. We show that the replacement of a conventional 90 degrees V-shaped electrode by an electrode with a hyperbolic profile substantially improves the peak shape of any given mass, and increases the mass resolution by a factor of 3-4 and the abundance sensitivity by a factor of 100. The potential of high analytical performance combined with electroforming techniques for electrode manufacture indicate future practical uses of such instruments. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
5.
The discovery of neutron rich isotopes of the lightest elements on the neutron drip line exhibiting a halo structure has opened
up new vistas in research activities. The novel structural features associated with the halo phenomena have been the subject
for extensive theoretical and experimental investigations in recent times. In this talk, I propose to present a broad overview
of the recent developments in this field, bringing out the striking features which show that a large number oflight nuclei
near the neutron drip line are characterized by a clear separation between a ‘normal’ core nucleus and a loosely bound low
density veil of neutrons. Specifically, the two neutron halos offer a natural premises, from a theoretical standpoint, to
employ three body techniques for studying their detailed structural properties. A considerable part of the talk will be devoted
to report and highlight the results on a number of light halo nuclei such as 11Li, 11Be, 19B and 22C on which we have been carrying out investigations employing a simple but realistic three body model. These three body systems
which have been termed as ‘Borromean’ (i.e while three body systems are bound, the corresponding binary subsystems on the
other hand are unbound) are characterized by large spacial extension and very low separation energy of the neutron. They are,
therefore, ideally suited for exploring the possibility of the existence of Efimov states in two neutron halo nuclei. We have
recently carried out the three body analyses to predict the possibility of the occurrence of such states on which experimental
work at various laboratories is underway. 相似文献
6.
Zanarini S Vankova S Hernandez S Ijeri VS Armandi M Garrone E Bonelli B Onida B Spinelli P 《Chemical communications (Cambridge, England)》2012,48(46):5754-5756
We report the first use of cobalt aluminophosphate (CoAPO5) as a water oxidation catalyst. A decrease in the overvoltage by about 0.2 V with respect to catalyst free FTO has been observed. Additionally, we show that CoAPO5, deposited on ITO or Pt, can also act as a photo-electro-catalyst, as it generates enhanced oxidation currents in the presence of light starting from a bias of +0.8 V vs. Ag/AgCl. 相似文献
7.
A coated-wire ion-selective electrode (ISE) based on cyclam (1,4,8,11-tetraazacyclotetradecane) as a neutral carrier in a polyvinyl chloride (PVC) matrix was fabricated for the determination of Ag(I) ions. The coated-wire ISE exhibited a linear Nernstian response over the range 1 x 10(-1) to 1 x 10(-7) M with a slope of 59 +/- 2 mV per decade change and a detection limit of 5 x 10(-8) M. The ISE shows a greater preference for Ag over other cations with good precision. The electrode was selective towards Ag(I) ions in the presence of 13 different metal ions tested. The selectivity coefficients (K(ij)) were determined for Na(I), K(I), Mg(II), Ca(II), Ba(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II) and Hg(II). The selectivity coefficients of these cations are in the range of 10(-4) to 10(-2). This ISE was used for the determination of free silver and total silver in electroplating bath solutions, additives and brighteners. 相似文献
8.
NL Asfandiarov AI Fokin VG Lukin EP Nafikova GS Lomakin VS Fal'ko YV Chizhov 《Rapid communications in mass spectrometry : RCM》1999,13(12):1116-1123
A series of anthraquinone (C(14)O(2)H(8)) derivatives has been studied by means of electron capture negative ion mass spectrometry (ECNI-MS), photoelectron spectroscopy (PES), and AM1 quantum chemical calculations. Mean lifetimes of molecular negative ions M(-.) (MNI) have been measured. The mechanism of long-lived MNI formation in the epithermal energy region of incident electrons has been investigated. A simple model of a molecule (a spherical potential well with the repulsive centrifugal term) has been applied for the analysis of the energy dependence of cross sections at the first stage of the electron capture process. It has been shown that a temporary resonance of MNI at the energy approximately 0.5 eV corresponds to a shape resonance with lifetime 1-2.10(-13) s in the f-partial wave (l = 3) of the incident electron. The next resonant state of MNI at the energy approximately 1.7 eV has been associated with the electron excited Feshbach resonance (whose parent state is a triplet npi* transition). In all cases the initial electron state of the MNI relaxes into the ground state by means of a radiationless transition, and the final state of the MNI is a nuclear excited resonance with a lifetime measurable on the mass spectrometry timescale. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
9.
10.
Vijaykumar Ijeri Francis Vocanson Claude Martelet Nicole Jaffrezic‐Renault 《Electroanalysis》2007,19(4):510-514
The possibility of using capacitance and flat band voltage as measurable quantities for determining amino acids that are neither electroactive nor with strong UV‐vis absorption has been explored. The sensors were fabricated by immobilizing calixarene derivatives on Si/SiO2/Si3N4 transducers. The measurements were made in sulfuric acid media of ca. pH 1 and in physiological buffer of pH 7.4. The different calixarene derivatives showed varying sensitivities to the amino acids ranging from 8 to 137 mV/decade. 相似文献