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431.
A novel fluorescence chemical sensor for the highly sensitive and selective determination of Pb2+ ions in aqueous solutions is described. The preliminary potentiometric and spectrofluorimetric complexation studies in solution revealed that the lipophilic ligand 5,8-bis((5′-chloro-8′-hydroxy-7′-quinolinyl)methyl)-2,11-dithia-5,8-diaza-2,6-pyridinophane (L2) forms a highly stable and selective [PbL2]2+ and [Pb(L2)2]2+ complexes which results in a strong fluorescence quenching of the ligand. Thus, a novel fluorescence Pb2+ sensing system was prepared by incorporating L2 as a neutral lead-selective fluoroionophore in the plasticized PVC membrane containing tetrakis(p-chlorophenyl) borate as a liphophilic anionic additive. The response of the sensor is based on the strong selective fluorescence quenching of L2 by Pb2+ ions. At pH 5.5, the proposed sensor displays a calibration curve over a wide concentration range of 3.0 × 10−7 to 2.5 × 10−2 M with a relatively fast response time of less than 5 min. In addition to high stability, reversibility and reproducibility, the sensor shows a unique selectivity towards Pb2+ ion with respect to common coexisting cations. The proposed fluorescence optode was successfully applied to the determination of lead in plastic toys and tap water samples. 相似文献
432.
Mahdi Sadeghi Milad Enferadi Hojjat Nadi 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):259-263
172Lu due to its suitable (T
1/2 = 6.7 days) and high detection sensitivity, is used as a radiotracer in different fields. 172Lu appears to be suitable as a long-lived rare-earth tracer for compound labelling and biodistribution studies. In the present
study, excitation functions via 172Yb(p,n)172Lu, natYb(p,xn)172Lu, 172Yb(d,2n)172Lu and natYb(d,xn)172Lu reactions were calculated by ALICE/91, ALICE/ASH and TALYS-1.2 codes. Deposition of natYb2O3 on Cu substrate was carried out via sedimentation method for the production of 172Lu. Cementation separation process and liquid–liquid extraction (LLX) of no-carrier-added (nca) radiolutetium from irradiated
ytterbium(III)oxide target hydrochloric solution was described using Na(Hg) amalgam, α-hydroxyisobutyric acid (α-HIB) and
di-(2-ethylhexyl)phosphoric acid (HDEHP). 相似文献
433.
Density, sound velocity and conductivity measurements are carried out on 1-heptyl-3-methylimidazolium bromide ([C7mim][Br]) in pure water and in aqueous solutions of sodium di-hydrogen citrate, di-sodium hydrogen citrate and tri-sodium citrate over a range of temperatures at atmospheric pressure. The experimental density and sound velocity data are used to calculate the apparent molar volume and isentropic compressibility as a function of temperature and concentration. The effects of temperature and charge on the anion of sodium citrate salts on the apparent molar volume and isentropic compressibility of [C7mim][Br] are studied. It was found that both of the apparent molar volume and isentropic compressibility of [C7mim][Br] in aqueous sodium citrate solutions are larger than those in pure water and increase by increasing temperature. The effects of temperature and charge on the anion of sodium citrate salts on the conductivity behavior of the investigated IL solutions are also studied. 相似文献
434.
The Optimization utilization of raw material and components is one of the main challenges in production and project management success. Executives usually face with waste and shortage of raw material which cause delay and cost, however the material and required components are usually provided more than needed. Therefore planning to provide these components from existing spools of material is one of these challenges especially when the number of the needed material pieces and the existing spools are high. For instance, in power plant projects cables are usually provided in form of spools which later cut down to required pieces in the project location. Extraction of each needed piece of cable from specific existing spool is a decision to be made. In this paper, a heuristic method based on integrating Integer Goal Programming and Taguchi Method is suggested to optimize cutting down process of these materials. 相似文献
435.
In this paper, we use the Laplace equation in curvature space S 2 with electromagnetic field, and write the Schrödinger equation in S 2space. By comparing this equation with well known polynomial we obtain the wave function and energy spectrum. In that case we face with two values of λ which guarantee the stability of system. On the other hand, we take advantage from factorization method, and factorize the second order equation in terms of first order equations. These first orders operators lead us to investigate the potential and super-potential which are satisfied by shape invariance condition. We show that, in order to have such condition the λ must be zero, the energy spectrum also obtained by this condition. Finally we show that these corresponding operators will be generators of algebra. 相似文献
436.
Abdalghani Daaoub James M. F. Morris Vanessa A. Béland Paul Demay-Drouhard Amaar Hussein Simon J. Higgins Hatef Sadeghi Richard J. Nichols Andrea Vezzoli Thomas Baumgartner Sara Sangtarash 《Angewandte Chemie (International ed. in English)》2023,62(24):e202302150
Most studies in molecular electronics focus on altering the molecular wire backbone to tune the electrical properties of the whole junction. However, it is often overlooked that the chemical structure of the groups anchoring the molecule to the metallic electrodes influences the electronic structure of the whole system and, therefore, its conductance. We synthesised electron-accepting dithienophosphole oxide derivatives and fabricated their single-molecule junctions. We found that the anchor group has a dramatic effect on charge-transport efficiency: in our case, electron-deficient 4-pyridyl contacts suppress conductance, while electron-rich 4-thioanisole termini promote efficient transport. Our calculations show that this is due to minute changes in charge distribution, probed at the electrode interface. Our findings provide a framework for efficient molecular junction design, especially valuable for compounds with strong electron withdrawing/donating backbones. 相似文献