The effects of media properties on the horseradish peroxidase-catalyzed fluorogenic reaction

The effects of media properties including buffers, acidity, solvents and surfactant on horseradish peroxidase-catalyzed fluorogenic reaction were investigated. The results showed that the so-called non-fluorescent hydrogen donors were in fact fluorescent. There existed an acid—base equilibrium in the fluorescent dimer product. For p -hydroxyphenylpropionic acid, a pK_a value of 8.0 for the product was obtained from its titration curve. The product fluorescence increased with higher pH, however, a longer time was needed to reach the reaction equilibrium due to the pH mismatch problem. Cationic micelles cetyltrimethylammonium bromide and cetyltrimethylammonium chloride could reduce the pH mismatch and offered a way to further increase the determination sensitivity. Finally, a micelle-enhanced flow-injection analysis of horseradish peroxidase is suggested.     

ALTERNATION THEORY IN APPROXIMATION BY POLYNOMIALS HAVING BOUNDED COEFFICIENTS

ＡＬＴＥＲＮＡＴＩＯＮＴＨＥＯＲＹＩＮＡＰＰＲＯＸＩＭＡＴＩＯＮＢＹＰＯＬＹＮＯＭＩＡＬＳＨＡＶＩＮＧＢＯＵＮＤＥＤＣＯＥＦＦＩＣＩＥＮＴＳＸＵＳＨＵＳＨＥＮＧ（许树声）（ＪｉａｎｇｎａｎＵｎｉｖｅｒｓｉｔｙ,Ｗｕｘｉ２１４０６３,Ｃｈｉｎａ）Ａｂｓ...     

非线性方程组的符号矩阵，正则分裂与单调包含（Ⅰ）

As a continuation of part I of the paper under the same title, we developgeneral monotonic enclosure methods for the couple systems of the splitting equations {x=G([x]a,[x]b,[y]c) y=G([y]a,[y]b,[x]c),which models the system of equations associated with hybrid and aaynchronotts monotonicity as well as convexity. The resulting algorithms and convergence theorems generalize and unify various known methods and monotonic enclosure theorents established by other authors.     

Mössbauer study of a novel series of ternary rare-earth iron-rich intermetallics: ND(Fe1-xTi x )6+y(x ∼ 0.1 and 0≤y≤5)

A study of the Nd-Fe-Ti phases at the Fe-rich end of the phase diagram has been carried out using⁵⁷Fe Mössbauer spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). In particular,⁵⁷Fe Mössbauer spectroscopy has been used to characterize the phases present in these samples. In addition to the two well-known 217 and 112 phases, twonovel phases have been identified, with compositions denoted by3–29 and9–94, which are closely linked to the orthorhombic ScFe₆Ga₆-type and the hexagonal TbCu₇-type structures, respectively. The possible crystal structures of these new phases will be discussed in terms of the dumbbell substitution sequence in the CaCu₅ structure.     

Origin and manifestation of the anharmonic potential felt by an ion-cloud in an actual Paul trap

The anharmonic potential felt by a single-species ions confined in a rf quadrupole trap which results from a non-ideal trap configuration and the charge distribution of the ion cloud is studied. The rf resonance-absorption spectra are explained by a Duffing oscillator and a representation of the line-shape parameter is derived. For > 0.77, the electric signals will exhibit hysteresis. The relation with the anharmonic potential is discussed.