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81.
Zusammenfassung Die Elektrodenfunktionen eines Glases, bestehend aus (Mol-%) 27% Na2O, 8% Al2O3 und 65% SiO2, wurden gegenüber verschiedenen Kationen geprüft. Die Glaselektrode zeigt eine ausgeprägte Silberfunktion und läßt sich als Indicatorelektrode bei der Fällungstitration des Silberions mit Halogenid im neutralen Medium einsetzen. Als günstigster Titrator erwies sich Magnesiumchlorid, das zu einem deutlichen Potentialsprung im Äquivalenzpunkt führt. Zweiwertige Kationen beeinflussen die Indizierung nicht, wohl aber stören größere Mengen an Alkaliionen.
Summary The electrode functions of a glass, containing (mol-%) 27% Na2O, 8% Al2O3, and 65% SiO2, have been tested against different cations. Such a glass electrode exhibits a distinct silver function and can be applied as indicator electrode to the precipitation titration of silver ion with halogenide in neutral medium. Magnesium chloride proved to be the most favourable titrator, yielding clear jumps in potential at the equivalence point. The indication is not influenced by divalent cations, larger amounts of alkali ions, however, interfere.相似文献
82.
Wojciech Chojnacki 《Communications in Mathematical Physics》1992,143(3):527-544
We establish a version of the spectral duality theorem relating the point spectrum of a family of*-representations of a certain covariance algebra to the continuous spectrum of an associated family of*-representations. Using that version, we prove that almost all the images of any element of a certain space of fixed points of some*-automorphism of an irrational rotation algebra via standard*-representations of the algebra inl
2 do not have pure point spectrum over any non-empty open subset of the common spectrum of those images. As another application of the spectral duality theorem, we prove that if almost all the Bloch operators associated with a real almost periodic function on have pure point spectrum over a Borel subset of , then almost all the Schrödinger operators with potentials belonging to the compact hull of the translates of this function have, over the same set, purely continuous spectrum.Dedicated to Professor Marek Burnat 相似文献
83.
The Hartree-Fock LCAO MO SCF formalism designed for molecular atom-antiatom systems has been proposed. The interlepton correlation
effects have been accounted for within the configuration interaction formalism. The method seems to be general for leptonic
systems and comprises other simplified approximations known in the literature. 相似文献
84.
[reaction: see text] Allyl, isopentenyl, geranyl, citronellyl, farnesyl, and phytyl alcohols were transformed in good yield (>60%) into their phosphorothioates via a DBU-assisted 1,3,2-oxathiaphospholane ring-opening condensation with 2-(2-cyanoethoxy)-2-thiono-1,3,2-oxathiaphospholane, a reagent that is stable and easy to handle, followed by subsequent removal of the 2-cyanoethyl group from the intermediate phosphorothioate diester under basic conditions. 相似文献
85.
Becker B Baranowska K Chojnacki J Wojnowski W 《Chemical communications (Cambridge, England)》2004,(5):620-621
A reaction of silanethiol and primary amine leads to a product whose crystals are built of well-defined supermolecules--assemblies of four ammonium silanethiolate units (RS(-)H(3)N(+)R')(4) with a novel, unusual 3D hydrogen bond pattern. 相似文献
86.
Józef Lipiński Henryk Chojnacki Zbigniew R. Grabowski Krystyna Rotkiewicz 《Chemical physics letters》1980,70(3):449-453
The energies of the low lying electronic states of p-cyano-N,N-dimethylaniline (CDMA) in its planar and in 90° twisted conformation have been calculated using the modified INDO method. Solvent effects have been taken into account. The results agree reasonably well with the experimental data and support the hypothesis of the dual fluorescence of CDMA as being related to the intramolecular rotation of the N(CH3)2 group, with a decisive role of the solvent polarity. 相似文献
87.
Anna Kowalkowska Konrad Chojnacki Maciej Multan Jan K. Maurin Edyta ukowska-Chojnacka Patrycja Wiska 《Molecules (Basel, Switzerland)》2022,27(14)
Antifungal N-phenacyl derivatives of 4,6- and 5,6-dibromobenzimidazoles are interesting substrates in the synthesis of new antimycotics. Unfortunately, their application is limited by the low synthesis yields and time-consuming separation procedure. In this paper, we present the optimization of the synthesis conditions and purification methods of N-phenacyldibromobenzimidazoles. The reactions were carried out in various base solvent-systems including K2CO3, NaH, KOH, t-BuOK, MeONa, NaHCO3, Et3N, Cs2CO3, DBU, DIPEA, or DABCO as a base, and MeCN, DMF, THF, DMSO, or dioxane as a solvent. The progress of the reaction was monitored using HPLC analysis. The best results were reached when the reactions were carried out in an NaHCO3–MeCN system at reflux for 24 h. Additionally, the cytotoxic activity of the synthesized compounds against MCF-7 (breast adenocarcinoma), A-549 (lung adenocarcinoma), CCRF-CEM (acute lymphoblastic leukemia), and MRC-5 (normal lung fibroblasts) was evaluated. We observed that the studied cell lines differed in sensitivity to the tested compounds with MCF-7 cells being the most sensitive, while A-549 cells were the least sensitive. Moreover, the cytotoxicity of the tested derivatives towards CCRF-CEM cells increased with the number of chlorine or fluorine substituents. Furthermore, some of the active compounds, i.e., 2-(5,6-dibromo-1H-benzimidazol-1-yl)-1-(3,4-dichlorophenyl)ethanone (4f), 2-(4,6-dibromo-1H-benzimidazol-1-yl)-1-(2,4,6-trichlorophenyl)ethanone (5g), and 2-(4,6-dibromo-1H-benzimidazol-1-yl)-1-(2,4,6-trifluorophenyl)ethanone (5j) demonstrated pro-apoptotic properties against leukemic cells with derivative 5g being the most effective. 相似文献
88.
Destler W.W. Chojnacki E. Hoeberling R.F. Lawson W. Singh A. Striffler C.D. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1988,16(2):71-89
Experimental and theoretical studies conducted at the University of Maryland on the production of high-power microwave radiation in cusp-injected, large-orbit devices are reviewed. Three classes of devices belonging to this category are discussed. In the first case, an axis-encircling rotating electron beam interacts via the negative mass instability with the modes of a smooth cylindrical waveguide, producing broadband radiation at multiple harmonics of the electron cyclotron frequency. In the second case, the beam interacts with a multiresonator magnetron circuit designed to provide mode control, resulting in high-power radiation at a desired cyclotron harmonic. In the third case, the beam interacts with a transverse wiggler magnetic field produced by samarium-cobalt magnets placed interior and/or exterior to the beam. In this last case the interaction is analogous to a circular-geometry free-electron laser. Experimental results form all three configurations are reviewed and compared with theoretical expectations. The possibility of enhanced operational efficiency in all of these devices by electron energy recovery is discussed and a design for a first experiment to test this concept is presented 相似文献
89.
Andrzej Maślanskiewicz Tadeusz Glowiak Henryk Chojnacki Leszek Skrzypek Adam Niedbala 《Journal of chemical crystallography》1995,25(4):165-169
The crystal and molecular structures of two isomeric 3,4- and 4,3-chloro-(methylthio)quinolines have been determined. For 3-chloro-4-(methylthio)-quinoline (3-Cl–4-MeS–Q); triclinic, space group
,a=7.199(3),b=7.919(3),c=8.921(3) Å, =89.74(3), =74.29(3), =78.55(3)°. For 4-chloro-3-(methylthio)quinoline (4-Cl–3-MeS–Q): monoclinic, space group P21/n,a=12.860(4),b=5.424(2),c=13.434(4) Å, =90.84(3)°. The values of the Cl...S distance as well as those for the Cl–C–C(S) and (Cl)C–C–S angles indicate the attractive interaction between ortho-situated heteroatoms in isomer 4-Cl–3-MeS–Q contrary to the effects observed in the case of 3-Cl–4-MeS–Q. The conclusions were confirmed by calculations of atomic charges withab initio method 4-31G basis set, which show positively charged sulfur atom in 4-Cl–3-MeS–Q and negatively charged sulfur in 3-Cl–4-MeS–Q.Part XXX in the series of Azinyl Sulfides. 相似文献
90.
[(η5-C5H5)ZrCl3] reacts with [C5H4CH2CH2NMe2]Li yielding the coordination polymer [(C5H5)(C5H4CH2CH2NMe2)ZrCl2]n (1) as a brown solid which is very sensitive to moisture. The reaction of 1 with 1.35 equivalent of HCl (methanolic solution) yields pale yellow green crystals of [(η5-C5H5)(η5-C5H4CH2CH2NHMe2)ZrCl2]2[ZrCl6] (2). Compound 2 was fully characterized on the basis of NMR data and X-ray crystal structure analysis. The formation of this product indicates the elimination of C5H4CH2CH2NMe2 as well as C5H5 ligands from the Zr(IV) metal centre. 相似文献