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J. Solymosi P. Zagyvai L. G. Nagy 《Journal of Radioanalytical and Nuclear Chemistry》1996,204(1):3-14
Electrolytes of alkaline zincate, acidified zinc sulphate, zinc-ammonia, zinc-ammonia-EDTA, zinc-EDTA/NaOH have been examined in order to verify their applicability for electrodeposition (ED) of zinc on stainless steel (SS) disc at ppm level. Operating parameters suitable for ED of zinc at 90% deposition (amount of zinc removed from plating solution) on SS disc using a total 1 ppm zinc in a 5 cm3 bath volume were determined. It helped to prepare radioactive source (65Zn) using inactive Zn as carrier. Speciation of zinc in a Zn-oxalate-EDTA-ammonia bath has been computed. 相似文献
54.
Mt Mikls Major Gerg Rvid Szabolcs Balogh Attila Bnyei Gyrgy Lendvay Dvid Frigyes Jzsef Bakos Gergely Farkas 《应用有机金属化学》2019,33(2)
A series of chiral pentane‐2,4‐diyl‐based thioether‐amine ligands [ 4 and 5 ; (R,S)‐ and (S,S)‐R1SCH(CH3)CH2CH(CH3)NHR2, respectively, where 4a R1 = iPr, R2 = Ph; 4b R1 = tBu, R2 = Ph; 4c R1 = 1‐Ad, R2 = Ph; 5a R1 = iPr, R2 = Ph; 5b R1 = tBu, R2 = Ph; 5c R1 = 1‐Ad, R2 = Ph; 5d R1 = iPr, R2 = 4‐MeOC6H4; 5e R1 = iPr, R2 = 4‐MeC6H4; 5f R1 = iPr, R2 = 3,5‐Me2C6H3] with stereogenic S‐ and N‐donor atoms has been prepared starting from cyclic sulfates via optically pure γ‐aminoalcohol or 2,4‐dimethylazetidine intermediates. The synthesis of the novel diastereomerically related ligand sets 4 and 5 was accomplished starting from the same source of chirality. The modular ligand structure and the novel synthetic strategies developed for their synthesis allowed the easy modification of the ligands’ (i) S‐ and (ii) N‐substituents, as well as (iii) the relative stereochemistry within the ligand backbone. Six‐membered [Pd(N,S)Cl2]‐type chelate complexes of the diastereomerically related ligands 4a and 5a were synthesized and characterized by X‐ray crystallography in the solid phase, by density functional theory calculations and in solution by NMR spectroscopy. The coordination of 5a resulted in the formation of a single chair conformation by the stereospecific locking of both stereolabile (N and S) donor atoms. In contrast, compound 4a forms rapidly equilibrating palladium species due to the fast inversion of the sulfur donor. Ligands with stereochemically fixed donor atoms provided robust and efficient catalytic systems that can be effectively applied in alkylene carbonates as green reaction media. Remarkably, the phosphine‐free catalysts are air‐stable, and at room temperature in the presence of moisture gave excellent ee’s (up to 93%) in asymmetric allylation processes thanks to the double stereoselective coordination. 相似文献
55.
Pter brnyi‐Balogh Mtys Milen Andrs Dancs Dvid Frigyes Lszl Pong Gyrgy Keglevich 《Heteroatom Chemistry》2013,24(3):226-233
New dihydro[3,2‐c][1,2,4]triazolo[4,3‐a]pyridines were synthesized by the reaction of 4‐(methylsulfanyl)‐6,7‐dihydrothieno[3,2‐c]pyridine with acid hydrazides. One bis(dihydrothienotriazolo‐pyridine) was also prepared. In a few cases, the corresponding intermediate could be detected by LC‐MS. The bromophenyl derivative was involved in Suzuki and Sonogashira cross‐coupling reactions. © 2013 Wiley Periodicals, Inc. Heteroatom Chem 24:226–233, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21087 相似文献
56.
We prove almost tight bounds on the number of incidences between points and k-dimensional varieties of bounded degree in R d . Our main tools are the polynomial ham sandwich theorem and induction on both the dimension and the number of points. 相似文献
57.
Abstract. Two triangles are called almost disjoint if they are either disjoint or their intersection consists of one common vertex. Let f(n) denote the maximum number of pairwise almost disjoint triangles that can be found on some vertex set of n points in 3-space. Here we prove that f(n)=Ω(n
3/2
) . 相似文献
58.
The adsorption, desorption, and reactions of ethanol have been investigated on pure and promoted ZSM-5 catalysts. FTIR spectroscopy indicated the formation of a strongly bonded ethoxy species on ZSM-5(80) at 300 K. TPD experiments following the adsorption of ethanol on both ZSM-5 and Mo2C/ZSM-5 have shown desorption profiles corresponding to unreacted ethanol and decomposition products (H2O, H2, CH3CHO, C4H10O, and C2H4). The main reaction pathway of ethanol on pure ZSM-5 is the dehydration reaction yielding ethylene, small amounts of hydrocarbons, and aromatics. Deposition of different additives, such as Mo2C, ZnO, and Ga2O3 on zeolite, greatly promoted the formation of benzene and toluene at 773-973 K, very likely by catalyzing the aromatization of ethylene formed in the dehydration process of ethanol. Separate studies of the reaction of ethylene revealed that the previous additives markedly enhanced the selectivity and the yield of aromatics on ZSM-5. 相似文献
59.
József Solymosi 《Advances in Mathematics》2009,222(2):402-408
We prove that the sumset or the productset of any finite set of real numbers, A, is at least |A|4/3−ε, improving earlier bounds. Our main tool is a new upper bound on the multiplicative energy, E(A,A). 相似文献
60.
The crossing number, cr(G), of a graph G is the least number of crossing points in any drawing of G in the plane. According to the Crossing Lemma of M. Ajtai, V. Chvátal, M. Newborn, E. Szemerédi, Theory and Practice of Combinatorics, North‐Holland, Amsterdam, New York, 1982, pp. 9–12 and F. T. Leighton, Complexity Issues in VLSI, MIT Press, Cambridge, 1983, the crossing number of any graph with n vertices and e>4n edges is at least constant times e3/n2. Apart from the value of the constant, this bound cannot be improved. We establish some stronger lower bounds under the assumption that the distribution of the degrees of the vertices is irregular. In particular, we show that if the degrees of the vertices are d1?d2?···?dn, then the crossing number satisfies \begin{eqnarray*}{\rm{cr}}(G)\geq \frac{c_{1}}{n}\end{eqnarray*} with \begin{eqnarray*}{\textstyle\sum\nolimits_{{{i}}={{{1}}}}^{{{n}}}}{{id}}_{{{i}}}^{{{3}}}-{{c}}_{{{2}}}{{n}}^{{{2}}}\end{eqnarray*}, and that this bound is tight apart from the values of the constants c1, c2>0. Some applications are also presented. © 2009 Wiley Periodicals, Inc. J Graph Theory 64: 12–21, 2010 相似文献