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31.
Binding of bis-picolylamine-naphthalene diimide-peptide nucleic acid conjugates to complementary DNA is strongly dependent upon Zn2+; ultimately, hybridization is switched ON in the presence muM Zn2+. 相似文献
32.
This study aims to clarify the effects of carbon activation type and physical form on the extent of adsorption capacity and
desorption capacity of a bi-solute mixture of phenol and 2-chlorophenol (2-CP). For this purpose, two different PACs; thermally
activated Norit SA4 and chemically activated Norit CA1, and their granular countertypes with similar physical characteristics,
thermally activated Norit PKDA and chemically activated Norit CAgran, were used. The thermally activated carbons were better
adsorbers for phenol and 2-CP compared with chemically activated carbons, but adsorption was more reversible in the latter
case. 2-CP was adsorbed preferentially by each type of activated carbon, but adsorption of phenol was strongly suppressed
in the presence of 2-CP. The simplified ideal adsorbed solution (SIAS) model underestimated the 2-CP loadings and overestimated
the phenol loadings. However, the improved and modified forms of the SIAS model could better predict the competitive adsorption.
The type of carbon activation was decisive in the application of these models. For each activated carbon type, phenol was
desorbed more readily in the bi-solute case, but desorption of 2-CP was less compared with single-solute. This was attributed
to higher energies of 2-CP adsorption. 相似文献
33.
H. A. Ergül S. Topcuo?lu E. Ölmez Ç. K?rbaşo?lu 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(1):133-136
Summary Radionuclide (137Cs, 238U, 232Th and 40K) concentrations were determined in a sediment trap and bottom sediment samples collected from a station at the eastern Turkish
coast of the Black Sea. The specific activity of the 137Cs radionuclide in the settling particles ranged from 0.04±0.01 to 0.10±0.02 Bq. g-1dry weight. The calculated flux rate of the 137Cs was between 0.37 and 2.59 Bq. m-2. d-1in the sampling periods of 2002 and 2003. The 137Cs concentration in the bottom sediment profile were between 0.039±0.013-9.083±0.017 Bq. g-1dry weight in the same station. The vertical profile of the radionuclides suggests that they have little mobility during the
17 years after the Chernobyl accident. 相似文献
34.
8-Hydroxyquinoline (8-HOQ) is known as an important chelating agent for several metal ions. This compound is practically insoluble in water. For this reason, in this study its water soluble sulfate salt has been used for complexing uranyl ions and the stability constants of the complex have been determined. The Irving-Rosotti method computing the Calvin-Bjerrum pH-titration data, was applied. Finally, the stability constants of the complex formed between (8-HOQN-H)2SO4 and uranyl ions were found to be lgK1=8.25 and lgK2=4.15, the overall stability constant being {ie55-1}. 相似文献
35.
K. Özker A. Sungur M. Ercan N. Ardagil N. Aydin 《Journal of Radioanalytical and Nuclear Chemistry》1987,118(3):201-208
The labelling of human serum albumin /HSA/ with99mTc has been investigated using a chemical method /stannous citrate/ and electrolytically generated tin/II/ ions. A comparative study of various chemical parameters and current intensities has been carried out in order to find the optimal conditions for labelling. The labelling yield was over 95%, for the chemical and electrolytical methods. 相似文献
36.
Although today unjustly neglected abroad and often even in his native land, Edvard Immanuel Hjelt (1855–1921), was an exceptionally gifted, dedicated, and multifaceted individual who made important contributions to chemistry, the history of chemistry, politics, and the management of national and international affairs. Little information about him is available in English. The present article supplements the only two English sources available [1, pp 66–83; 2] and makes this chemist-statesman better known to those chemists and historians who do not read Swedish or Finnish.In this section we present articles by leading scientific historians that chronicle the important events, persons, and publications that make up the rich history of chemical science. The history, and the articles in this ection often make that very clear. Chemists and their research are always influenced by current events. These articles are intended to describe the setting in which important discoveries occurred and to humazine their discoveres. 相似文献
37.
In this study, the Schiff base ligands H2L1–H2L3 and their CuII, CoII, NiII, FeIII RuIII and VOIV complexes have been prepared and characterized by spectroscopic and analytical techniques. All the complexes are mononuclear.
Keto-enol tautomeric forms of the ligands have been investigated in polar and apolar solvents. The ligands favor the keto-form
in the C7H8 and C6H14. The C–C coupling reaction of the 2,6-di-t-butylphenol has been investigated by the CoII and CuII complexes. Thermal properties of the complexes have been assessed using thermal techniques and similar properties were found.
In the FeIII and RuIII complexes, firstly, the coordinated water molecule is lost from the complex; in the second step, the chloride ion leaves
the molecule in the 300–350 °C temperature range. Finally, the complexes decompose to the appropriate metal oxide at the higher
temperature ranges. The electrochemical properties of the complexes have been studied in the two different solvents (DMF and
CH3CN). 相似文献
38.
Composite of polyacrylamide-bentonite (PAA-B) was prepared by direct polymerisation of PAA in a suspension of bentonite (B). Adsorption and thermodynamic features of phytic acid (Phy) adsorption onto B, PAA and PAA-B, and those of Fe3+, Zn2+, UO2
2+ adsorption onto PAA-B and its modification by Phy (PAA-B-Phy) have been investigated. The reusability, storagability, ion selectivity and recoverability of sorbed ions with 1 M HCl have also been considered.The chemical and physical structure of adsorbents has been characterised by means of FT-IR and XRD. All adsorption isotherms for Phy and the ions were L-type of the Giles classification except, the one which is S type for adsorption of Phy onto PAA. The maximum adsorption capacities for the ions adsorbed were in order of UO2
2+ > Fe3+ > Zn2+ for PAA-B and Zn2+ > Fe3+ > UO2
2+ for PAA-B-Phy. Langmuir equilibrium constants for the adsorption of ions onto PAA-B-Phy were significantly higher than those found for PAA-B; the magnitude of increase for UO2
2+ was about 100. The thermodynamic parameters indicated that adsorption reactions are spontaneous in terms of adsorption free enthalpy.The chemical structure of PAA-B-Phy was not changed at the end of the studies of reusability and storagability. The composite was selective for UO2
2+ of the ions of interest.The composite of PAA-B and its modification by Phy have been used for the first time in this investigation. It is proposed that the composites can be practically used in the investigations and applications of adsorption. 相似文献
39.
The structureless background at X-ray and low energy -ray region, resulting from bremsstrahlung due to the stopping of -radiations, causes serious problems in nuclear spectroscopy. In this study, in order to reduce the background and therefore to increase the sensitivity of the nuclear analytical technique and the number of elements observable, a methodology is developed to deflect the -particles by a magnetic field. The experimental setup consists of a permanent magnet /1 kG/, Ge/Li/ solid-state detector, and multichannel analyzer. 相似文献
40.
Thorsteinn Loftsson Ína B. Össurardóttir Thorsteinn Thorsteinsson Matt Duan Már Másson 《Journal of inclusion phenomena and macrocyclic chemistry》2005,52(1-2):109-117
The natural β-cyclodextrin (βCD) and its complexes have limited solubility in aqueous solutions. This low aqueous solubility, as well as low aqueous solubility of the guest molecule (i.e. triclosan or triclocarban (TCC)), can result in low complexation efficiency (CE). The purpose of this study was to enhance the apparent intrinsic solubility (S
0) of the guest molecule and its βCD complexes through ionization and addition of auxiliary compounds such as polymers, amino acids and metal ions. Both triclosan (pK
a
7.9) and TCC (pK
a
12.7) are weak acids. Addition of ethanol to the complexation medium enhanced S
0 of both triclosan and TCC but at the same time ethanol lowered the stability constant (K
c
) of their βCD complexes resulting in overall lowering of CE. Addition of small amount of water-soluble polymers enhanced the βCD solubilization of both guests, and addition lysine enhanced the solubilization of TCC. Ionization of triclosan resulted in significant enhancement of CE and enhanced triclosan release from tablets containing triclosan/βCD complex. The effect of ionization was not as pronounced in the case of TCC.This revised version was published online in July 2005 with a corrected issue number. 相似文献