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81.
Pei Dang 《Mathematical Methods in the Applied Sciences》2015,38(2):365-379
In this study, we propose some new uncertainty principles for periodic signals with sharper lower bounds than those in the existing ones. The improved lower bounds, in particular, are related to the frequency of the signal. Three examples are employed to demonstrate sharpness of the new uncertainty principles. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
82.
Signal moments for the short‐time Fourier transform associated with Hardy–Sobolev derivatives 下载免费PDF全文
M. Liu K.I. Kou J. Morais P. Dang 《Mathematical Methods in the Applied Sciences》2015,38(13):2719-2730
The short‐time Fourier transform has been shown to be a powerful tool for non‐stationary signals and time‐varying systems. This paper investigates the signal moments in the Hardy–Sobolev space that do not usually have classical derivatives. That is, signal moments become valid for non‐smooth signals if we replace the classical derivatives by the Hardy–Sobolev derivatives. Our work is based on the extension of Cohen's contributions to the local and global behaviors of the signal. The relationship of the moments and spreads of the signal in the time, frequency and short‐time Fourier domain are established in the Hardy–Sobolev space. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
83.
Genetic profile characterization and population study of 21 autosomal STR in Chinese Kazak ethnic minority group 下载免费PDF全文
Xiao‐Ye Wang Chun‐Mei Shen Wen‐Juan Liu Jiang‐Wei Yan Hong‐Dan Wang Hong‐Wei Pu Yan‐Li Wang Guang Yang Yu‐Dang Zhang Hao‐Tian Meng Hang Jing Bo‐Feng Zhu 《Electrophoresis》2014,35(4):503-510
Short tandem repeat loci have been recognized as useful tools in the routine forensic application and in recent decades, more and more new short tandem repeat (STR) loci have been constantly discovered, studied, and applied in forensic caseworks. In this study, we investigated the genetic polymorphisms of 21 STR loci in the Kazak ethnic minority as well as the genetic relationships between the Kazak ethnic minority and other populations. Allelic frequencies of 21 STR loci were obtained from 114 unrelated healthy Kazak individuals in the Ili Kazak Autonomous Prefecture, Xinjiang Uigur Autonomous Region of China. We observed a total of 159 alleles in the group with the allelic diversity values ranging from 0.0044 to 0.5088. The highest polymorphism was found at D19S433 locus and the lowest was found at D1S1627. Statistical analysis of the generated data indicated no deviation from Hardy–Weinberg equilibriums at all 21 STR loci. In order to estimate the population differentiation, allelic frequencies of all STR loci of the Kazak were compared with those of other neighboring populations using analysis of molecular variance method. Statistically significant differences were found between the studied population and other populations at 2–7 STR loci. A neighbor‐joining tree was constructed based on allelic frequencies of the 21 STR loci and phylogenetic analysis indicates that the Kazak has a close genetic relationship with the Uigur ethnic group. The present results may provide useful information for forensic sciences and population genetics studies, and can also increase our understanding of the genetic background of this group. The present findings showed that all the 21 STR loci are highly genetically polymorphic in the Kazak group, which provided valuable population genetic data for the genetic information study, forensic human individual identification, and paternity tests. 相似文献
84.
Qun Dang Zhibo Zhang Bingyu Tang Yang Song Ling Wu Tongqian Chen Stephane Bogen Vinay Girijavallabhan David B. Olsen Peter T. Meinke 《Tetrahedron letters》2014
To discover novel nucleosides as potential antiviral agents, 2′-spirolactam and 2′-spiropyrrolidine-containing nucleoside analogs were envisioned. Efficient synthetic routes were developed with an epoxide opening as the key step to establish the quaternary center at the 2′ position, leading to the design and synthesis of uridine analogs 8 and 21, prodrugs 13–16, and cytidine analog 11. 相似文献
85.
Qun Dang Zhibo Zhang Shuangsheng He Yaohong Liu Tongqian Chen Stephane Bogen Vinay Girijavallabhan David B. Olsen Peter T. Meinke 《Tetrahedron letters》2014
To discover novel nucleosides as potential antiviral agents, 4′-spirocyclic phosphono-nucleosides were designed to mimic the monophosphate of R-1479, a known nucleoside inhibitor of HCV NS5B. Bypassing the first kinase step to nucleoside monophosphate is viewed as advantageous since this phosphorylation is often observed as the rate-limiting transformation to the active NTP for many nucleosides. Efficient synthetic routes were developed with a triphenylphosphine–iodine cyclization reaction as the key step to form the tetrahydrofuran 4′-spirocycle. The desired 4′-spirocyclic phosphono-cytidine analogs 12a, 12b, and 16 were prepared in 11 steps. 相似文献
86.
Xiaowei Yi Gongshuo Yu Jiamei Zhang Haitao Zhang Mei Li Haijun Dang 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1987-1991
A new method is developed for the determination of energy peak efficiency of 208 keV γ-ray of 237U based on 241Pu/237U secular equilibrium. Plutonium solution was purified to remove Am with Dowex 1 × 2 anion exchange chromatography and the concentration of 241Pu in the purified solution was determined using 242Pu isotope-dilution mass spectrometry on an inductively-coupled plasma mass spectrometry. The solution can be used as calibration source for the determination of energy peak efficiency of 208 keV γ-ray of 237U after 48 days. The method was validated for a planar HPGe detector at the 12 mm above the detector surface. The results showed that this is a simple and economic method for determining the energy peak efficiency of gamma detectors for 208 keV γ-ray of 237U. 相似文献
87.
Specific ion effects on the electrophoretic mobility of small,highly charged peptides: A modeling study 下载免费PDF全文
Stuart A. Allison Hengfu Wu Tuyen M. Bui Lac Dang Giang H. Huynh Tam Nguyen Linda Soegiarto Bi C. Truong 《Journal of separation science》2014,37(17):2403-2410
In this work, we use coarse‐grained modeling to study the free solution electrophoretic mobility of small highly charged peptides (lysine, arginine, and short oligos thereof (up to nonapeptides)) in NaCl and Na2SO4 aqueous solutions at neutral pH and room temperature. The experimental data are taken from the literature. A bead modeling methodology that treats the electrostatics at the level of the nonlinear Poisson Boltzmann equation developed previously in our laboratory is able to account for the mobility of all peptides in NaCl, but not Na2SO4. The peptide mobilities in Na2SO4 can be accounted for by including sulfate binding in the model and this is proposed as one possible explanation for the discrepancy. Oligo arginine peptides bind more sulfate than oligo lysines and sulfate binding increases with the oligo length. 相似文献
88.
Leia Fan Elaine Jian Wen-Chun Chang Yvonne Wu Jason Lin Andy Tseng Jessica Tseng Renee Wan Annie Yu Eric Lee 《Electrophoresis》2022,43(21-22):2227-2233
Diffusiophoresis phenomenon of aoft particles suspended in binary electrolyte solutions is explored theoretically in this study based on the spherical cell model, focusing on the chemiphoresis component in absence of diffusion potential. Both the electrostatic and hydrodynamic aspects of the boundary confinement, or steric effect, due to the presence of neighboring particles are examined extensively under various electrokinetic conditions. Significant local extrema are found in mobility profiles expressed as functions of the Debye length in general, synchronized with the strength of the motion-inducing double layer polarization. Moreover, a seemingly peculiar phenomenon is observed that the soft particles may move faster in more concentrated suspensions. The competition between the simultaneous enhancement of the motion-inducing electric driving force and the motion-retarding hydrodynamic drag force from the boundary confinement effect of the neighboring particles is found to be responsible for it. The above findings are also demonstrated experimentally in a very recent study on the diffusiophoretic motion of soft particles through porous collagen hydrogels. The results presented here are useful in various practical applications of soft particles like drug delivery. 相似文献
89.
Yan Fang Yangzom Dawa Qilan Wang Yue Lv Wei Yu Gang Li Jun Dang 《Journal of separation science》2022,45(14):2435-2445
Saxifraga atrata is an important traditional Tibetan medicine used to treat cough and pneumonia, and has tremendous medicinal potential. In this study, we devised a technique to separate 1,1-diphenyl-2-picrylhydrazyl inhibitors from a methanol extract of S. atrata. The material was first processed using MCI GEL CHP20P medium-pressure liquid chromatography, yielding 1.1 g of the target fraction Fr2. Subsequently, online hydrophilic interaction liquid chromatography-1,1-diphenyl-2-picrylhydrazyl assay was used to identify prospective 1,1-diphenyl-2-picrylhydrazyl inhibitors, and two 1,1-diphenyl-2-picrylhydrazyl inhibitor fractions (Fr24 and Fr25) were identified from Fr2. Then, medium-pressure preparation was continued using an XIon column to separate two 1,1-diphenyl-2-picrylhydrazyl inhibitor fractions (Fr24 and Fr25). The target compound was concentrated in fractions Fr24 and Fr25 using reverse-phase liquid chromatography during further separation procedures. Finally, the purity, structure, and 1,1-diphenyl-2-picrylhydrazyl inhibitory activity of the isolated 1,1-diphenyl-2-picrylhydrazyl inhibitors were determined. Two 1,1-diphenyl-2-picrylhydrazyl inhibitors (adenosine with the half maximal inhibitory concentration of 66.87 ± 14.33 μM and (-)-4-O-(E)-caffeoyl-l -threonic acid with the half maximal inhibitory concentration of 59.06 ± 5.02 μM) were isolated with purities exceeding 95%. The results showed that this technology is effective in the targeted separation of antioxidants from natural products. 相似文献
90.
Kamel Arraki Perle Totoson Alain Decendit Andy Zedet Justine Maroilley Alain Badoc Cline Demougeot Corine Girard 《Molecules (Basel, Switzerland)》2021,26(6)
Polyphenolic enriched extracts from two species of Cyperus, Cyperus glomeratus and Cyperus thunbergii, possess mammalian arginase inhibitory capacities, with the percentage inhibition ranging from 80% to 95% at 100 µg/mL and 40% to 64% at 10 µg/mL. Phytochemical investigation of these species led to the isolation and identification of two new natural stilbene oligomers named thunbergin A-B (1–2), together with three other stilbenes, trans-resveratrol (3), trans-scirpusin A (4), trans-cyperusphenol A (6), and two flavonoids, aureusidin (5) and luteolin (7), which were isolated for the first time from C. thunbergii and C. glomeratus. Structures were established on the basis of the spectroscopic data from MS and NMR experiments. The arginase inhibitory activity of compounds 1–7 was evaluated through an in vitro arginase inhibitory assay using purified liver bovine arginase. As a result, five compounds (1, 4–7) showed significant inhibition of arginase, with IC50 values between 17.6 and 60.6 µM, in the range of those of the natural arginase inhibitor piceatannol (12.6 µM). In addition, methanolic extract from Cyperus thunbergii exhibited an endothelium and NO-dependent vasorelaxant effect on thoracic aortic rings from rats and improved endothelial dysfunction in an adjuvant-induced arthritis rat model. 相似文献