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81.
Summary. In this paper, interpolatory quadrature formulas based upon the roots of unity are studied for certain weight functions.
Positivity of the coefficients in these formulas is deduced along with computable error estimations for analytic integrands.
A comparison is made with Szeg? quadrature formulas. Finally, an application to the interval [-1,1] is also carried out.
Received February 29, 2000 / Published online August 17, 2001 相似文献
82.
Haitham A. Badr Abdelaleim I. ElSayed Hafiz Ahmed Miriam V. Dwek Chen-zhong Li Leyla B. Djansugurova 《Applied biochemistry and biotechnology》2013,171(4):963-974
The terminal monosaccharide of glycoconjugates on a eukaryotic cell surface is typically a sialic acid (Neu5Ac). Increased sialylation usually indicates progression and poor prognosis of most carcinomas. Here, we utilize two human mammary epithelial cell lines, HB4A (breast normal cells) and T47D (breast cancer cells), as a model system to demonstrate differential surface glycans when treated with sialic acid under nutrient deprivation. Under a starved condition, sialic acid treatment of both cells resulted in increased activities of α2→3/6 sialyltransferases as demonstrated by solid phase assay using lectin binding. However, a very strong Maackia amurensis agglutinin I (MAL-I) staining on the membrane of sialic acid-treated T47D cells was observed, indicating an increase of Neu5Acα2→3Gal on the cell surface. To our knowledge, this is a first report showing the utility of lectins, particularly MAL-I, as a means to discriminate between normal and cancer cells after sialic acid treatment under nutrient deprivation. This method is sensitive and allows selective detection of glycan sialylation on a cancer cell surface. 相似文献
83.
Jacob A. Orkwis Ann K. Wolf Syed M. Shahid Corinne Smith Leyla Esfandiari Greg M. Harris 《Macromolecular bioscience》2020,20(9)
Severe peripheral nervous system injuries currently hold limited therapeutic solutions. Existing clinical techniques such as autografts, allografts, and newer nerve guidance conduits have shown variable outcomes in functional recovery, adverse immune responses, and in some cases low or minimal availability. This can be attributed in part to the lack of chemical, physical, and electrical cues directing both nerve guidance and regeneration. To address this pressing clinical issue, electrospun nanofibers and microfibers composed of piezoelectric polyvinylidene flouride‐triflouroethylene (PVDF‐TrFE) have been introduced as an alternative template for tissue engineered biomaterials, specifically as it pertains to their relevance in soft tissue and nerve repair. Here, biocompatible scaffolds of PVDF‐TrFE are fabricated and their ability to generate an electrical response to mechanical deformations and produce a suitable regenerative microenvironment is examined. It is determined that 20% (w/v) PVDF‐TrFE in (6:4) dimethyl formamide (DMF):acetone solvent maintains a desirable piezoelectric coefficient and the proper physical and electrical characteristics for tissue regeneration. Further, it is concluded that scaffolds of varying thickness promoted the adhesion and alignment of Schwann cells and fibroblasts. This work offers a prelude to further advancements in nanofibrous technology and a promising outlook for alternative, autologous remedies to peripheral nerve damage. 相似文献
84.
Bromination of alkenes, alkynes, and aromatic amines has efficiently been carried out at room temperature in short reaction times using HIO3/KBr in CH2Cl2/H2O (1:1) to prepare corresponding brominated compounds in excellent yields. 相似文献
85.
Murat Aydemir Akın Baysal Feyyaz Durap Bahattin Gümgüm Saim Özkar Leyla Tatar Yıldırım 《应用有机金属化学》2009,23(11):467-475
The reactions of thiophene‐2‐(N‐diphenylphosphino)methylamine, Ph2PNHCH2‐C4H3S, 1 and thiophene‐2‐[N,N‐bis(diphenylphosphino)methylamine], (Ph2P)2NCH2‐C4H3S, 2, with MCl2(cod) (M = Pd, Pt; cod = 1,5‐cyclooctadiene) or [Cu(CH3CN)4]PF6 yields the new complexes [M(Ph2PNHCH2‐C4H3S)2Cl2], M = Pd 1a, Pt 1b, [Cu(Ph2PNHCH2‐C4H3S)4]PF6, 1c, and [M(Ph2P)2NCH2‐C4H3S)Cl2], M = Pd 2a, Pt 2b, {Cu[(Ph2P)2NCH2‐C4H3S]2}PF6, 2c, respectively. The new compounds were isolated as analytically pure crystalline solids and characterized by 31P‐, 13C‐, 1H‐NMR and IR spectroscopy and elemental analysis. Furthermore, the solid‐state molecular structures of representative palladium and platinum complexes of bis(phosphine)amine, 2a and 2b, respectively, were determined using single crystal X‐ray diffraction analysis. The palladium complexes were tested as potential catalysts in the Heck and Suzuki cross‐coupling reactions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
86.
Azizollah Habibi Leyla Mousavifar Issa Yavari Mohammad R. Yazdanbakhsh 《Monatshefte für Chemie / Chemical Monthly》2007,138(6):603-606
Summary. Alkyl isocyanides undergo a smooth reaction with alkylidene Meldrum’s acids in the presence of arylhydroxylamines to produce N
1-alkyl-2-(3,5-dioxo-2-aryltetrahydro-4-isoxazolyl)alkanamides in high yields. 相似文献
87.
88.
Leyla Onat 《Comptes Rendus Mathematique》2010,348(17-18):997-1000
89.
Let \(I_{n}\) be the symmetric inverse semigroup on \(X_{n}=\{1,\ldots ,n\}\), and let \(DP_{n}\) and \(ODP_{n}\) be its subsemigroups of partial isometries and of order-preserving partial isometries on \(X_{n}\) under its natural order, respectively. In this paper we find the ranks of the subsemigroups \(DP_{n,r}=\{ \alpha \in DP_{n}:|\mathrm {im\, }(\alpha )|\le r\}\) and \(ODP_{n,r}=\{ \alpha \in ODP_{n}: |\mathrm {im\, }(\alpha )|\le r\}\) for \(2\le r\le n-1\). 相似文献
90.
Leyla Daruis Pablo Gonzá lez-Vera Olav Njå stad. 《Mathematics of Computation》2002,71(238):683-701
In this paper we are concerned with the estimation of integrals on the unit circle of the form by means of the so-called Szegö quadrature formulas, i.e., formulas of the type with distinct nodes on the unit circle, exactly integrating Laurent polynomials in subspaces of dimension as high as possible. When considering certain weight functions related to the Jacobi functions for the interval nodes and weights in Szegö quadrature formulas are explicitly deduced. Illustrative numerical examples are also given.