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21.
The neuroactive algal metabolite (-)-isodomoic acid C, a kainoid amino acid, has been synthesized for the first time. Asymmetric dearomatizing cyclization of an aromatic amide using a chiral lithium amide base generates a bicyclic enone containing a pyrrolidinone ring with the relative and absolute stereochemistry of the target. A further 15 synthetic steps, including conjugate cuprate addition to the enone of a side chain precursor, a Ru-promoted oxidation of the phenyl ring to the C2-carboxylic acid substituent, a regioselective Baeyer-Villiger reaction, and an E-selective Horner-Wadsworth-Emmons reaction, elaborate the cyclization product into the target molecule. 相似文献
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The dynamics of modulated waves are studied in the one-dimensional discrete nonlinear electrical transmission line. The contribution of the linear dispersive capacitance is taken into account, and it is shown via the reductive perturbation method that the evolution of such waves in this system is governed by the higher-order nonlinear Schrödinger equation. Passing through the Stokes analysis, we establish a generalized criterion for the Benjamin-Feir instability in the network and determine the exact solutions of the obtained wave equation by using the Pathria-Morris approach. 相似文献
25.
The strong infrared absorption in the ν3 S–F stretching region of sulphur hexafluoride (SF6) near 948 cm?1 makes it a powerful greenhouse gas. Although its present concentration in the atmosphere is very low, it is increasing rapidly, due to industrial pollution. The ground state population of this heavy species is only 32% at room temperature and thus many hot bands are present. Consequently, a reliable remote-sensing spectroscopic detection and monitoring of this species require an accurate modelling of these hot bands. We used two experimental set-ups at the SOLEIL French synchrotron facility to record some difference and combination bands of SF6: (1) a new cryogenic multiple pass cell with 93 m optical path length and regulated at 163 ± 2 K temperature and (2) the Jet-AILES supersonic expansion set-up. With this, we could obtain high-resolution absorption spectra of the ν3 ? ν1, ν3 ? ν2, ν1 + ν3 and ν2 + ν3 bands at low temperature. These spectra could be assigned and analysed, thanks to the SPVIEW and XTDS computer programs developed in Dijon. We performed two global fits of effective Hamiltonian parameters. The first one is a global fit of the ground state, ν2, ν3, ν3 ? ν2, ν2 + ν3, 2ν3 and 2ν3 ? ν3 rovibrational parameters, using the present spectra and previous infrared, Raman and two-photon absorption data. This allows a consistent refinement of the effective Hamiltonian parameters for all the implied vibrational levels and a new simulation of the 2ν3 + ν2 ? ν2 hot band. The second global fit involves the present ν3 ? ν1 and ν1 + ν3 lines, together with previous ν1 Raman data, in order to obtain refined ν1 parameters and also ν1 + ν3 parameters in a consistent way. This allows to simulate the ν3 + ν1 ? ν1 hot band. 相似文献
26.
Salah E. M. Eltom Ahmed A. H. Abdellatif Hamzah Maswadeh Mohsen S. Al-Omar Atef A. Abdel-Hafez Hamdoon A. Mohammed Eiman ME. Agabein Ibrahim Alqasoomi Salem A. Alrashidi Mohammed S. M. Sajid Mugahid A. Mobark 《Molecules (Basel, Switzerland)》2021,26(12)
The ostrich oil of Struthio camelus (Ratite) found uses in folk medicine as an anti-inflammatory in eczema and contact dermatitis. The anti-inflammatory effect of a γ-lactone (5-hexyl-3H-furan-2-one) isolated from ostrich oil and its formulated nano-emulsion in formalin-induced paw edema was investigated in this study. Ostrich oil was saponified using a standard procedure; the aqueous residue was fractionated, purified, and characterized as γ-lactone (5-hexyl-3H-furan-2-one) through the interpretation of IR, NMR, and MS analyses. The γ-lactone was formulated as nano-emulsion using methylcellulose (MC) for oral solubilized form. The γ-lactone methylcellulose nanoparticles (γ-lactone-MC-NPs) were characterized for their size, shape, and encapsulation efficiency with a uniform size of 300 nm and 59.9% drug content. The γ-lactone was applied topically, while the formulated nanoparticles (NPs) were administered orally to rats. A non-steroidal anti-inflammatory drug (diclofenac gel) was used as a reference drug for topical use and ibuprofen suspension for oral administration. Edema was measured using the plethysmograph method. Both γ-lactone and γ-lactone-MC-NPs showed reduction of formalin-induced paw edema in rats and proved to be better than the reference drugs; diclofenac gel and ibuprofen emulsion. Histological examination of the skin tissue revealed increased skin thickness with subepidermal edema and mixed inflammatory cellular infiltration, which were significantly reduced by the γ-lactone compared to the positive control (p-value = 0.00013). Diuretic and toxicity studies of oral γ-lactone-MC-NPs were performed. No diuretic activity was observed. However, lethargy, drowsiness, and refusal to feeding observed may limit its oral administration. 相似文献
27.
Coussot G Faye C Ibrahim A Ramonda M Dobrijevic M Le Postollec A Granier F Vandenabeele-Trambouze O 《Analytical and bioanalytical chemistry》2011,399(6):2295-2302
The functionalization of surfaces with amino groups is used in many application areas such as in industrial biocatalytic processes
for the development of medical biomaterials and in the environment for removing pollutants from water. Amino group density
and grafting stability are often related to functionalized material performances; thus, their characterizations are of prime
importance. The determination of amino density and grafting stability on polymeric material (e.g. polypropylene, polystyrene
and cylco olefin copolymer) is often time consuming and sometimes presents technical constraints, more particularly with non-flat
materials. In this paper, we report a novel colorimetric assay using the Coomassie Brilliant Blue dye for both amino density
determination and grafting stability measurement. The assay named ADECA for “Amino Density Estimation by Colorimetric Assay”
is sensitive, rapid, robust and versatile. We demonstrate that ADECA makes the evaluation of aminated materials performances
possible for numerous material compositions, formats and chemistries used for grafting. Our study focuses on dendrigraft of
poly-l-lysine and poly(amidoamine) dendrimers dendritic materials. 相似文献
28.
Schleifman EB Bindra R Leif J del Campo J Rogers FA Uchil P Kutsch O Shultz LD Kumar P Greiner DL Glazer PM 《Chemistry & biology》2011,18(9):1189-1198
Peptide nucleic acids (PNAs) bind duplex DNA in a sequence-specific manner, creating triplex structures that can provoke DNA repair and produce genome modification. CCR5 encodes a chemokine receptor required for HIV-1 entry into human cells, and individuals carrying mutations in this gene are resistant to HIV-1 infection. Transfection of human cells with PNAs targeted to the CCR5 gene, plus donor DNAs designed to introduce stop codons mimicking the naturally occurring CCR5-delta32 mutation, produced 2.46% targeted gene modification. CCR5 modification was confirmed at the DNA, RNA, and protein levels and was shown to confer resistance to infection with HIV-1. Targeting of CCR5 was achieved in human CD34(+) hematopoietic stem cells (HSCs) with subsequent engraftment into mice and persistence of the gene modification more than four months posttransplantation. This work suggests a therapeutic strategy for CCR5 knockout in HSCs from HIV-1-infected individuals, rendering cells resistant to HIV-1 and preserving immune system function. 相似文献
29.
Huang F Kuo HK Hsieh CH Wu PC Wu YC Wang CJ 《Applied biochemistry and biotechnology》2012,166(3):632-639
In addition to the traditional lithotripsy treatment, extracorporeal shockwaves (ESWs) have been shown to be effective in
the treatment of certain musculoskeletal disorders and in enhancing skin flap neovascularization. However, relatively little
is known about its effect on melanocytes. To investigate its effect on the melanogenic activity of cultured melanocytes, mouse
B16F10 melanocytes were treated with defocused ESWs of different energies (15, 21, and 27 kV) and at different doses (300
and 600 impulses). Cell viability was measured 1 and 24 h after treatment. Melanin content was measured and compared against
a standard curve generated with fungal melanin. Cellular tyrosinase activity was calculated with the 3,4-dihydroxyphenylalanine
(DOPA) oxidase assay. The results demonstrated that ESW treatment reduced cell viability. Our results also indicated that
the overall decrease in cell viability lasted for 6 days. After ESW treatment with 300 or 600 impulses at 21 kV, no significant
change in melanin content or tyrosinase activity of the B16F10 melanocytes was noted as compared to those of the control.
The present study suggests that ESW treatment does not alter the melanogenic activity of the cultured melanocytes. 相似文献
30.
羧甲基纤维素钠水凝胶的制备及其生物降解性研究 总被引:9,自引:0,他引:9
用羧甲基纤维素钠(CMC—Na)制得了含水量高达98%的水凝胶,考察了防腐剂、交联剂、无机态氮素、有机态氮素、碳水化合物的加入量以及环境中pH值等因素对生物降解性的影响。结果表明:制备条件不同,水凝胶的生物降解性不同;环境中一定量铵根离子的存在有利于水凝胶的生物降解;在pH=5.2的环境中纤维素酶活性最高,降解程度最大。 相似文献