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21.
Sergio A. Celani 《Central European Journal of Mathematics》2003,1(4):561-572
In this paper we shall give a topological representation for Hilbert algebras that extend the topological representation given
by A. Diego in [4]. For implicative semilattices this representation gives a full duality. We shall also consider the representation
for Boolean ring. 相似文献
22.
Sergio Albeverio Yeneng Sun Jiang-Lun Wu 《Transactions of the American Mathematical Society》2007,359(2):517-527
It is shown that for a large collection of independent martingales, the martingale property is preserved on the empirical processes. Under the assumptions of independence and identical finite-dimensional distributions, it is proved that a large collection of stochastic processes are martingales essentially if and only if the empirical processes are also martingales. These two results have implications on the testability of the martingale property in scientific modeling. Extensions to submartingales and supermartingales are given.
23.
Sergio Albeverio Volodymyr Koshmanenko Mykola Pratsiovytyi Grygoriy Torbin 《Positivity》2006,10(1):39-49
We introduce the conflict interaction with two positions between a couple of image probability measures and consider the associated
dynamical system. We prove the existence of invariant limiting measures and find the criteria for these measures to be a pure
point, absolutely continuous, or singular cotinuous as well as to have any topological type and arbitary Hausdorff dimension. 相似文献
24.
The electrochemical behavior and amperometric-FIA quantification of minoxidil at a glassy carbon electrode is described. The procedure is based on electrochemical oxidation at 0.800 V (vs. Ag/AgCl/NaCl(3 M) in a phosphate buffer solution. Minoxidil was determined over the range 1 x 10(-7) - 1 x 10(-4) M. Different analytical parameters and electrode stability were analyzed to obtain the best electrode performance. The optimal conditions were: working potentials, 0.800 V; flow rate, 0.74 mL min(-1); and solution pH 7.0. This system allowed a sampling rate of 120 samples per hour without any pretreatment. The proposed method was used for minoxidil quantification in pharmaceutical preparations with satisfactory results. The accuracy of FIA-amperometric method was established by a comparison with the conventional UV determination technique using a paired t-test indicating the absence of systematic errors. 相似文献
25.
Sergio O. Vasquez Colin D. Flint Ralph Sabry-Grant 《Journal of Applied Spectroscopy》1995,62(5):979-985
Published in Zhurnal Prikladnoi Spectroscopii, Vol. 62, No. 5, pp. 213–220, September–October, 1995. 相似文献
26.
A diastereoselective [4+2] annulation of vinyl carbodiimides with chiral N-alkyl imines has been developed to access the stereochemically rich tricyclic core of the batzelladine alkaloids. Its application to the asymmetric synthesis of batzelladine D permitted the use of long-range, directed hydrogenation and stereoselective intramolecular iodoamination as additional key steps to establish the remaining stereocenters within the natural product with excellent stereocontrol. 相似文献
27.
Reactions of pyridine‐2‐carboxaldehyde (9) with α,α′‐dibromo‐o‐ and p‐xylenes led to the corresponding bis‐pyridinium aldehydes 10 and 14. These aldehydes were quite reactive and the respective hydrates 11 and 15 were also formed. Cyclization of 10 or 11 with 48% HBr led to 12 while cyclization with PPA followed by conversion to the bis tribromide and loss of bromine led to 1. Cyclization of 14 or 15 with 48% HBr led to 3. Attempts to react α,α′‐dibromo‐m‐xylene with pyridine‐2‐carboxaldehyde (9) were not successful for the preparation of the bis‐pyridinium aldehyde 13. The bis‐pyridinium acetals 4, 5 and 6 were prepared and cyclized to afford 1, 2 and 3 , respectively, by the previously reported procedures. The structures of 1 and 2 were verified by 1H‐NMR and 13C‐NMR spectroscopy while that of 3 was confirmed by X‐ray analysis. 相似文献
28.
Apparent molal heat capacities
of some piperidine, morpholine, and piperazine derivatives in aqueous solution have been determined by adiabatic calorimetry
in the temperature range 20–55°C and in the molality range 0.2–1m. Comparison of experimental
values with those calculated through group contributions, found for monofunctional compounds, indicates strong interactions
between the hydrophilic centers. An interpretation is given of the possible mechanism of this interaction. Also, values of
ΔC
p
for the addition reaction of proton to nitrogen centers of mono- and bifunctional organic compounds are examined. 相似文献
29.
A direct and reagent free procedure has been developed to monitor the fermentation process of pine apple nectar using Attenuated Total Reflectance Fourier-transform mid-infrared spectrometry (FT-IR) and multivariate analysis. A classical 42 design for standards was employed for calibration using the information in the spectral range from 907 to 1531 cm−1 of the first order derivative spectra after mean centering of infrared data. The root mean square error of calibration (RMSEC) of 0.040, 0.021, 0.063 and 0.074% w/w were obtained for glucose, fructose, saccharose and ethanol, respectively, and a mean relative validation error of 2.9, 2.1, 2.6 and 3.6% was achieved for glucose, fructose, saccharose and ethanol. Results obtained by the proposed procedure for the alcohol content at different fermentation levels were statistically comparable with those obtained by a reference spectrometric method. So, FT-IR spectrometry provides a fast alternative to long and tedious classical procedures to ethanol determination and sugar enzymatic analysis. 相似文献
30.
Gallo E Caselli A Ragaini F Fantauzzi S Masciocchi N Sironi A Cenini S 《Inorganic chemistry》2005,44(6):2039-2049
A reproducible synthesis of a competent epoxidation catalyst, [Ru(VI)(TPP)(O)2)] (TPP = tetraphenylporphyrin dianion), starting from [Ru(II)(TPP)(CO)L] (L = none or CH3OH), is described. The molecular structure of the complex was determined by using ab initio X-ray powder diffraction (XRPD) methods, and its solution behavior was in detail investigated by NMR techniques such as PGSE (pulsed field gradient spin-echo) measurements. [Ru(IV)(TPP)(OH)]2O, a reported byproduct in the synthesis of [Ru(VI)(TPP)(O)2], was synthesized in a pure form by oxidation of [Ru(II)(TPP)(CO)L] or by a coproportionation reaction of [Ru(VI)(TPP)(O)2] and [Ru(II)(TPP)(CO)L], and its molecular structure was then determined by XRPD analysis. [Ru(VI)(TPP)(O)2] can be reduced by dimethyl sulfoxide or by carbon monoxide to yield [Ru(II)(TPP)(S-DMSO)2] or [Ru(II)(TPP)(CO)(H2O)], respectively. These two species were characterized by conventional single-crystal X-ray diffraction analysis. 相似文献