Let Σn be the unit sphere inRn for somen≥3 with centre at the origin, L(Σn) the space of all functions integrable on Σn. We prove a theorem on the representation of functions by singular integrals at double Lebesgue points, which is analogous
to a theorem by D. K. Faddeev in the one-dimensional case. On the basis of this theorem, we give necessary and sufficient
conditions for the fulfillment of the relation
В работе докаэывается достаточное условие для ограниченности функции Лебега линеиных средних рядов Фуряе-Лапласа. Иэ него
и ранее полученнои Калянеем оценки выведены необходимые и достаточные условия сходимости линеиных средных рядов Фуря’е-Лапласа
непрерывных функции, определенных на единичнои сфере в Rn (n>-3) с центром в начале координат. Это является аналогом иэвестного реэулятата Николяского для тригонометрических рядов.
Authors:Maosheng Ran, Ping Xie, Xiaohai Tang, Guangfu Zeng and Jinliang Yang
A newly proposed method for detecting content of adriamycin in pectin–adriamycin conjugate has been developed and evaluated. The content of adriamycin was detected by selective degradation of adramycin to adriamycinone. It was realized by a two-phase reaction system (water–chloroform reaction system), in which adriamycin was quantitatively converted to adriamycinone. Therefore, the latter can be used to calculate the precise content of adramycin in the polymer drug. To develop the method, the catalyst for degradation, the extraction solvent for adriamycinone, the temperature and time of degradation, and the ratio of pectin–adriamycin conjugate were investigated. The optimal reaction condition was as follows: 30 mg of pectin–adriamycin conjugate dissolved in 25 mL of water was added to a mixture of 25 mL of hydrochloric acid (1.5 mol/L) and 50 mL of chloroform; the mixture was heated to 40 °C to react for 1.5 h; after that, the mixture was extracted with chloroform for three times, and then the organic layer was combined and, subsequently, evaporated to remove solvent. Under this condition, adriamycinone generation rate reached 99.87%. The quantitative method was evaluated for linearity, the limit of detection (LOD) and limit of quantitation (LOQ), recovery, accuracy, robustness, and precision. The recoveries were between 99.47% and 101.07% with relative standard deviation <1.23%. The LOD and LOQ were 0.06 and 0.17 μg/mL, respectively. Compared to the traditional ultraviolet (UV) detection, this method is considered to be more precise for detecting content of adriamycin in its polymer conjugate.
This article explores a method of evaluating the comprehensive competitiveness of American universities in Bridge Engineering, which is beneficial for students’ picking up an ideal university for further study in America. Making use of ESI database, SCI database and EI database as well as the ranking of American universities from U.S. News and World Report, the author evaluates the comprehensive competitiveness of American universities in Bridge Engineering, and then develops the ranking of comprehensive competitiveness of American universities in Bridge Engineering specialty. From the ranking, the author reaches the conclusion that American universities such as University of Illinois-Urbana-Champaign and Georgia Institute of Technology and so on, have comparatively higher international influence and competitiveness in the field of Bridge Engineering.
Authors:Yonggang Li, Xiaohong Liu, Rui Zhang, DerGer ZomPa, Ping Luo, Lin Tang, Xiao Liu, Yan Zhou and Sheng Wen
A reliable isotope dilution method for the determination of chloramphenicol (CAP) in drinking water was developed by using an evaporation preparative step. Each sample was monitored by ultrahigh-pressure liquid chromatography (UHPLC) coupled to tandem mass spectrometry (MS/MS) using an electrospray ionization interface (ESI) in negative ion modes. Recoveries of spiked samples were in the range from 93.2% to 95.7% with intra-day relative standard deviation lower than 6.7% and inter-day relative standard deviation lower than 8.2%. Limit of quantification (LOD) was 0.002 ng/mL. The developed method was successfully applied to the analysis of CAP in drinking water of Shannan region of Tibet.