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51.
Instrumental neutron activation analysis (INAA) methods have been developed for the simultaneous determination of multielement
concentrations in both particulate and soluble fractions of atmospheric wet precipitation (AWP). Samples of AWP collected
across Canada by Canadian Network for Sampling Precipitation (CANSAP) have been analyzed. The INAA method involves four sequential
irradiations and counting after five different decay periods for measuring Ag, Al, As, Au, Ba, Br, Ca, Ce, Cl, Co, Cr, Cu,
Dy, Fe, Hf, Hg, I, K, La, Mg, Mn, Na, Rb, Sb, Sc, Se, Sm, Sr, Ti V and Zn. Precision and accuracy of the INAA methods have
been evaluated, and detection limits have been calculated. 相似文献
52.
Jeffry D. Madura Yasushi Nakajima Rodney M. Hamilton Andrzej Wierzbicki Arieh Warshel 《Structural chemistry》1996,7(2):131-138
The interactions between biologically important enzymes and drugs are of great interest. In order to address some aspects of these interactions we have initiated a program to investigate enzymedrug interactions. Specifically, the interactions between one of the isozymes of carbonic anhydrase and a family of drugs known as sulfonamides have been studied using computational methods. In particular the electrostatic free energy of binding of carbonic anhydrase II with acetazolamide, methazolamide,p-chlorobenzenesulfonamide,p-aminobenzenesulfonamide and three new compounds (MK1, MK2, and MK3) has been computed using finite-difference Poisson-Boltzmann (FDPB) [1] method and the semimacroscopic version [2, 3] of the protein dipole Langevin dipole (PDLD) method [4]. Both methods, FDPB and PDLD, give similar results for the electrostatic free energy of binding even though different charges and different treatments were used for the protein. The calculated electrostatic binding free energies are in reasonable agreement with the experimental data. The potential and the limitation of electrostatic models for studies of binding energies are discussed. 相似文献
53.
A spectrophotometric flow-injection procedure is described for fluoride in aqueous samples. The method is based on the decrease in absorbance of the zirconium/alizarin red S complex at 520 nm; linear response is obtained for the range 0.1–10 mg l?1 fluoride at a sampling rate of 100 h?1. Aluminum(III), iron(III) and phosphate interfere. 相似文献
54.
55.
We are using the coordinating anion tetrakis(imidazolyl)borate to construct new metal-organic framework structures. In this report, we present three alkaline earth metal network solids incorporating this anion. All three compounds have the same formula, M[B(Im)(4)](2)(H(2)O)(2) (M = Mg, Ca, Sr), and the same coordination environment about the metal. However, the three compounds have different network structures with different degrees of hydrogen bonding; the Mg material forms a two-dimensional network and the Ca and Sr compounds form one-dimensional chains. In addition, we present the structure of the protonated anion B(HIm)(Im)(3) as a model for the default structure of this anion and discuss how the conformation of tetrakis(imidazolyl)borate can affect the structure of network solids. 相似文献
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57.
J. Říkovská A. Machová W. D. Hamilton J. Dupák Chan Chen Mo M. Finger N. A. Lebedev B. S. Neganov V. N. Pavlov A. F. Shchus 《Czechoslovak Journal of Physics》1979,29(6):620-639
The anisotropy of the angular distribution of gamma-rays from the decay of156Tb, oriented in a gadolinium matrix at low temperatures, has been measured at the angles of 0 and π/2 with respect to the applied magnetic field direction in the range of temperatures from 14·6 to 68·4 mK. The temperature dependence of anisotropy was measured for the first time. The parameters of hyperfine magnetic dipole and electric quadrupole splittings have been determined and the values of the magnetic dipole moment ¦Μ156¦=(9·6±1·3)×10?27 J/T and the electric quadrupole momentQ 156=(2·9±0·9)×10?28 m2 of the156Tb ground state have been calculated. Multipole mixing ratios andB(E2) branching ratios of many gamma-ray transitions occurring in156Gd have been found and the results have been discussed in terms of the rotational-vibration and pairing-plus-quadrupole models. 相似文献
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59.
Donna Leamy Fiona Regan 《International journal of environmental analytical chemistry》2013,93(10):867-877
The potential of an optical sensing material for determination of metal ions in wastewater streams is presented. The initial results in the development of a chromo-ionophore-based optical sensor for metal ions are detailed. An azo dye species, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (BrPADAP), together with an ionophore and plasticiser was immobilised in a film of poly(vinyl chloride) (PVC). Initial investigations using the dye-impregnated sensing film showed a reproducible and reversible response to Pb(II) ions in aqueous solution. The response of this sensing film to Pb(II) at pH 6 was found to be linear in the 0.1-10 mg/L range, with a %RSD of 1.55%. The film can be regenerated by immersion in a low-pH buffer solution. The authors demonstrate how this method shows potential for analysis using once-off sensing probes. The sensing film response for Pb(II) occurs within 30 s. 相似文献
60.