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1.
Batch measurements have shown that the collection yields of chitosan for chromium(III), iron(III), nickel, copper(II), zinc and mercury(II) from sulphuric acid solutions are higher when the solutions contain ammonium sulphate, or when chitosan conditioned in ammonium sulphate is used, particularly at pH 3.0 and 5.0. The contrary is verified for the oxy-anions vanadate, chromate and molybdate. Manganese is never collected. At pH 1.0 no collection occurs. A procedure for recycling chromatographic columns includes fixation of Cu or Ni from a sulphate solution at pH 3-5 on sulphate-conditioned chitosan, and elution with 0.1M sulphuric acid/0.1M ammonium sulphate at pH 1.0; the presence of sulphate in the eluent obviates the detrimental effect of sulphuric acid on the next cycle. Sulphate is the favoured counter-ion of the chelated cations and its action produces shorter chromatographic bands. The interaction of sulphate with chitosan is discussed in terms of crystallinity and steric distribution of the protonated amino-groups in the polymer. Data on the new diethylaminohydroxypropylcellulose are included. 相似文献
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Stephen MT Hoke Gaoyang Liang A Irina Mutiu Julie Genereaux Christopher J Brandl 《BMC biochemistry》2007,8(1):16
Background
Spt7 is an integral component of the multi-subunit SAGA complex that is required for the expression of ~10% of yeast genes. Two forms of Spt7 have been identified, the second of which is truncated at its C-terminus and found in the SAGA-like (SLIK) complex. 相似文献3.
Colpaert F Mangelinckx S Rocchetti MT De Kimpe N 《Organic & biomolecular chemistry》2011,9(2):549-558
α-Methoxy- and α-ethoxyketones, as important intermediates in organic synthesis and flavor compounds in food chemistry, were synthesized by deprotonation of N-(1-alkoxy-2-propylidene)isopropylamine, prepared by condensation of the corresponding α-alkoxyacetone with isopropylamine, and subsequent reaction of the corresponding 1-azaallylic anions with alkyl halides to afford α'-alkylated, α-alkylated and α,α'-dialkylated ketimines. Hydrolysis of the imino function led to the desired substituted α-alkoxyketones. The ratio of α-, α'-, and α,α'-(di)alkylated compounds depended on the amount of base used and on the nature of the alkylating reagent. 相似文献
4.
Piermarco Cannarsa Genni Fragnelli Dario Rocchetti 《Journal of Evolution Equations》2008,8(4):583-616
We give null controllability results for some degenerate parabolic equations in non divergence form on a bounded interval.
In particular, the coefficient of the second order term degenerates at the extreme points of the domain. For this reason,
we obtain an observability inequality for the adjoint problem. Then we prove Carleman estimates for such a problem. Finally,
in a standard way, we deduce null controllability also for semilinear equations.
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R. A. A. Muzzarelli R. Rocchetti G. Marangio 《Journal of Radioanalytical and Nuclear Chemistry》1972,10(1):17-25
Nuclear fuel solutions atpH=2.5 can be passed through 7×1 cm chitin or chitosan columns to fix the Zr, Nb, Ce and Ru radioisotopes. This rapid and quantitative
separation clears the γ-ray spectrum of the solution from the main activity contribution and leaves the137Cs spectrum alone for accurate Cs determination. The process can be extended to radioactive waste waters. 相似文献
10.
The determination of vanadium in sea water by hot graphite atomic absorption spectrometry on chitosan after separation from salt 总被引:1,自引:0,他引:1
The anion-exchange behaviour of chitosan toward metavanadate was studied in salt solutions at different pH values. Filtered and acidified sea water was passed through a 500-mg chitosan column. Vanadium was determined by atomic absorption spectrometry with a graphite furnace and a deuterium background corrector on 5-mg aliquots of the homogenized column. The method was assessed for the 0.2–12.0 μg V 1-1 interval on the basis of the linear response for proportional amounts of vanadium in saline solutions and sea water and in the absence of interferences from smoke during atomization. Two sea-water samples gave 0.71±0.09 and 0.52±0.04 μg V 1-1. 相似文献