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51.
Two new compounds, 7'-(3',4'-dihydroxyphenyl)-N-[(4-methoxyphenyl)ethyl]propenamide (4), and 7'-(4'-hydroxy,3'-methoxyphenyl)-N-[(4-butylphenyl)ethyl]propenamide (5) have been isolated from Cuscuta reflexa along with five known compounds, 6,7-dimethoxy-2H-1-benzopyran-2-one (1), 3-(3,4-dihydroxyphenyl)-2-propen-1-ethanoate (2), 6,7,8-trimethoxy-2H-1-benzopyran-2-one (3), 3-(4-O-beta-D-glucopyranoside-3,5-dimethoxyphenyl)-2-propen-1-ol (6), 2-(3-hydroxy-4-methoxyphenyl)-3,5-dihydroxy-7-O-beta-D-glucopyranoside-4H-1-benzopyrane-4-one (7), reported for the first time from this species. Structures of these compounds were determined by spectral analysis. These compounds showed strong inhibitory activity against alpha-glucosidase.  相似文献   
52.
Transformation of dehydroepiandrosterone (DHEA) (1) was carried out by a plant pathogen Rhizopus stolonifer, which resulted in the production of seven metabolites. These metabolites were identified as 3beta,17beta-dihydroxyanandrost-5-ene (2), 3beta,17beta-dihydroxyandrost-4ene (3), 17beta-hydroxyandrost-4-ene-3-one (4), 3beta,11-dihydroxyandrost-4-ene-17-one (5), 3beta,7alpha-dihydroandrost-5-ene-17-one (6), 3A,7alpha,17beta-trihydroxyandrost-5-ene (7) and 11beta-hydroxyandrost-4,6-diene-3,17-dione (8). The structures of the transformed products were determined by the spectroscopic techniques.  相似文献   
53.
The uniformly third-order WENO-BO-Z scheme has been proposed previously in an attempt to restore third-order accuracy at the second-order critical point via the reduction of nonlinear dissipation followed by the modification of nonlinear weights as well as to improve the intermediate bandwidth property of the linear optimal stencil of the classical WENO-JS scheme with respect to both dispersion and dissipation. However, a problem-dependent nonlinear switch was employed to turn on in the intermediate range of wavenumbers to avoid unnecessary nonlinear adaption of the WENO scheme and was mainly dependent on the trial-and-error threshold value of a switch parameter. In order to avoid the problem-dependent nature of this switch, a problem-independent nonlinear switch is suggested and investigated in this work. Benchmark problems, ranging from non-broadband to broadband, are solved using the WENO-BO-Z scheme, and a comparison of the suggested switch with the problem-dependent switch is made.  相似文献   
54.
Anisotropic microarchitectures with different physicochemical properties have been developed as advanced materials for challenging industrial and biomedical applications including switchable displays, multiplexed biosensors and bioassays, spatially‐controlled drug delivery systems, and tissue engineering scaffolds. In this study, anisotropic biohybrid microparticles (MPs) spatio‐selectively conjugated with two different antibodies (Abs) are first developed for fluorescence‐based, multiplexed sensing of biological molecules. Poly(acrylamide‐co‐acrylic acid) is chemically modified with maleimide‐ or acetylene groups to introduce different targeting biological moieties into each compartment of anisotropic MPs. Modified polymer solutions containing two different fluorescent dyes are separately used for electrohydrodynamic co‐jetting with side‐by‐side needle geometry. The anisotropic MPs are chemically stabilized by thermal imidization, followed by bioconjugation of two different sets of polyclonal Abs with two individual compartments via maleimide‐thiol coupling reaction and Huisgen 1,3‐dipolar cycloaddition. Finally, two compartments of the anisotropic biohybrid MPs are spatio‐selectively associated with the respective monoclonal Ab‐immobilized substrate in the presence of the antigen by sandwich‐type immunocomplex formation, resulting in their ordered orientation due to the spatio‐specific molecular interaction, as confirmed by confocal laser scanning microscopy. In conclusion, anisotropic biohybrid MPs capable of directional binding have great potential as a new fluorescence‐based multiplexing biosensing system.

  相似文献   

55.
Plants are under constant assault by biotic and abiotic agents. When an elicitor is prologued, an immense reprogramming of plant gene expression and defense responses are initiated, which could be a natural source for potential drug development and insertional mutagenesis. In this regard, differential expression analysis of a medicinal plant Moringa oleifera was performed for bioactive genes at seedling stage, using differential display-RT-PCR technique. Infected seedlings with a fungus Fusarium solani collected at different time intervals, showed a massive change in their gene expression profile. The data analysis revealed that at least 150 pathogen-induced and about 60 suppressed genes were differentially expressed at 8-h postinoculation of the biotic stress. Fifty-five selective genes were disunited and reamplified. Sequence analysis of these potential genes illustrated that these genes had properties of some induced peroxidase mRNA, cell proliferation, others were mitogen activated protein kinases, ribosomal protein genes, defense regulating genes, and a few also had structural properties. Further studies about the utility of these genes in plant metabolism could assist to develop improved transgenic breeds with enhanced value of infection tolerance not only of M. oleifera but of other cultivars also.  相似文献   
56.
This work investigated the synthesis of biphenyl‐3,3′,4,4′‐tetracarboxylic dianhydride and benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride derivatives ( 3a – e and 6a – e ) with different substituted phenols via Friedel‐Crafts acylation reaction in the presence of dilute sulfuric acid. Dianhydride derivatives with 3‐N,N′‐dimethylamino phenol ( 3d and 6d ) and resorcinol ( 3e and 6e ) have been found to be highly fluorescent. The structures of all newly synthesized compounds were confirmed by the chromatographic, spectral and elemental data. Electrochemical study was done to determine to band gap energy, LUMO and HOMO levels energy. Band gap and LUMO energy levels were found to be lowest in xanthene derivatives substituted with 3‐N,N′‐dimethylamino group having value 2.24 and 4.85 eV respectively.  相似文献   
57.
The synthesis of several fluorinated isocoumarins and 3,4-dihydroisocoumarins are described. The structures of the synthesized compounds were confirmed by spectral and elemental analysis. All synthesized compounds were evaluated for their anti-inflammatory and antioxidant activity. These compounds were found to present antioxidant and anti-inflammatory activities. A few of them were found to be significantly active in vivo against ear edema in mice produced by 12-O-tetradecanoylphorbol-13-acetate (TPA) and also good radical scavengers.  相似文献   
58.
59.
A novel diamine monomer, pyridine-2, 6-bis((4-aminophenyl)thioureido)carbonyl(PATC) was synthesized efficiently and polymerized with various aromatic dianhydrides. Consequently, poly(pyridine thiourea-imide)s(PPTIs) with good thermal properties and flame retardancy were fabricated. The structures of PATC and PPTIs were characterized by FTIR, 1H-NMR, 13C-NMR spectroscopy along with elemental analysis, crystallinity, organosolubility, inherent viscosity and gel permeation chromatographic measurements. PPTIs containing C=S, CONH and meta substituted pyridine moieties in the polymer backbone showed amorphous nature and were readily soluble in highly polar organic solvents and even in less polar solvents such as tetrahydrofuran(THF). Polymers had inherent viscosities in the range of 0.91-1.16 d L/g and molecular weight was found between 68000-77000 g/mol. The electrical properties of the PPTIs were estimated in terms of dielectric constant over a range of frequencies. Their thermal stability was determined by 10% weight loss temperature found in the range of 519-563 °C under inert atmosphere. The glass transition temperature of the polyimides varied between 247 °C and 267 °C. The flame retardant properties of PPTIs were investigated in terms of limiting oxygen index(LOI) which was found in the range of 38.26-39.95. Introduction of thiourea in the polymer backbone is an effective way to improve the thermal stability and flame retardancy. Thus PATC can be considered as an excellent candidate for the synthesis of high performance polymers.  相似文献   
60.
Dual wavelength configurations normally employed to eradicate the effects of variable signal losses in intensity-dependent optical sensors are discussed. Particular attention is paid to the referencing capability of each configuration in relation to the major sources of measurement contamination. Illustrative examples of generic type sensor system implementations are provided and assessed to identify areas of any serious shortcomings. It is found that while full referencing can be achieved with both single and dual LED systems the maximum achievable performance will be dependent on the extent of differential spectral effects which can occur because of a finite wavelength separation between the two optical signals.  相似文献   
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