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141.
One defines the notion of universal deformation quantization: given any manifold M, any Poisson structure Λ on M and any torsionfree linear connection ? on M, a universal deformation quantization associates to this data a star product on (M, Λ) given by a series of bidifferential operators whose corresponding tensors are given by universal polynomial expressions in the Poisson tensor Λ, the curvature tensor R and their covariant iterated derivatives. Such universal deformation quantization exist. We study their unicity at order 3 in the deformation parameter, computing the appropriate universal Poissoncohomology. 相似文献
142.
We present in this paper a thermodynamic model for flow induced crystallization of a thermoplastic. The thermomechanical framework (generalized standard materials) allows us to couple in a very natural way the kinetics of crystallization with the mechanical history experienced by the thermoplastic[1]. In describing the viscoelastic properties of the polymer with a molecular theory, we obtain a model for flow-induced crystallization that couples the chain conformation to the kinetics of crystallization. This model intends to be valid both for shearing and elongation. We present the equations for two cases: Maxwell and Pom-Pom constitutive equations. We finally illustrate our model with injection molding simulations achieved with a dedicated Finite Element code. 相似文献
143.
Alaa A. Khojah Guillermo F. Padilla-Gonzlez Ammar Bader Monique J. S. Simmonds Michael Munday Michael Heinrich 《Molecules (Basel, Switzerland)》2021,26(20)
This study investigated the in vitro inhibitory potential of different solvent extracts of leaves of Barbeya oleoides on key enzymes related to type 2 diabetes mellitus (α-glucosidase and α-amylase) in combination with an aggregation assay (using 0.01% Triton X-100 detergent) to assess the specificity of action. The methanol extract was the most active in inhibiting α-glucosidase and α-amylase, with IC50 values of 6.67 ± 0.30 and 25.62 ± 4.12 µg/mL, respectively. However, these activities were significantly attenuated in the presence of 0.01% Triton X-100. The chemical analysis of the methanol extract was conducted utilizing a dereplication approach combing LC-ESI-MS/MS and database searching. The chemical analysis detected 27 major peaks in the negative ion mode, and 24 phenolic compounds, predominantly tannins and flavonol glycosides derivatives, were tentatively identified. Our data indicate that the enzyme inhibitory activity was probably due to aggregation-based inhibition, perhaps linked to polyphenols. 相似文献
144.
Hajer Ammar Imen Touihri Ahmed Eid Kholif Yassine MRabet Rym Jaouadi Mireille Chahine Mario E. de Haro Marti Einar Vargas-Bello-Prez Karim Hosni 《Molecules (Basel, Switzerland)》2022,27(20)
The main objective of this research was to study the biological characteristics in terms of antioxidant and antimicrobial activities of Ajuga iva and determine the best analytical and extraction methods applicable to this specie and studied compounds. A short screening of its nutritional value in terms of chemical composition is also included. A. iva leaves were analyzed for crude protein (CP), cell wall [neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL)], minerals, fatty acids, essential oils, and phenolic compounds. Mature aerial parts of A. iva were randomly collected during the Spring season from Mograne-Zaghouan, Tunisia. Leaves of A. iva contained 13.4 ± 0.4% CP, 26.3 ± 0.35% NDF, 20.2 ± 0.42% ADF, and 5.13 ± 0.21% ADL. Mineral content (13.0 ± 0.45%) was mainly composed of potassium (4.5% g DM) and magnesium (4.25% DM). Leaves of A. iva had linolenic (26.29 ± 0.760%) and linoleic (37.66 ± 2.35%) acids as the main components of the acid profile. Thymol was found to be the most dominant (23.43%) essential oil, followed by 4-vinylguaiacol (14.27%) and linalool (13.66%). HPLC-PDA-ESI-MS/MS analysis pointed out the presence of phytoecdysteroids. Phenolic acids and flavonoids, such as glycosylated derivatives of naringenin, eriodyctiol, and apigenin, were detected in the methanol extract of A. iva leaves. Our results underline the importance of choosing proper extraction methods and solvents to extract and characterize the described compounds profile of A. iva leaves. Results also show A. iva leaves as a potential source of functional ingredients with beneficial health-promoting properties. Overall, leaves of A. iva have low biological activities (antioxidant and antimicrobial activities) with a chemical composition suitable as a feed for ruminants in rangeland pasture. It also has low-grade antibacterial or medicinal characteristics when fed to ruminants. 相似文献
145.
Soukaina Hrichi Raja Chabane-Banaoues Filippo Alibrando Ammar B. Altemimi Oussama Babba Yassine Oulad El Majdoub Habib Nasri Luigi Mondello Hamouda Babba Zine Mighri Francesco Cacciola 《Molecules (Basel, Switzerland)》2022,27(20)
The antifungal drugs currently available and mostly used for the treatment of candidiasis exhibit the phenomena of toxicity and increasing resistance. In this context, plant materials might represent promising sources of antifungal agents. The aim of this study is to evaluate for the first time the chemical content of the volatile fractions (VFs) along with the antifungal and anti-biofilm of Convolvulus althaeoides L. roots. The chemical composition was determined by gas chromatography coupled to a flame ionization detector and mass spectrometry. In total, 73 and 86 chemical compounds were detected in the n-hexane (VF1) and chloroform (VF2) fractions, respectively. Analysis revealed the presence of four main compounds: n-hexadecenoic acid (29.77%), 4-vinyl guaiacol (12.2%), bis(2-ethylhexyl)-adipate (9.69%) and eicosane (3.98%) in the VF extracted by hexane (VF1). n-hexadecenoic acid (34.04%), benzyl alcohol (7.86%) and linoleic acid (7.30%) were the main compounds found in the VF extracted with chloroform (VF2). The antifungal minimum inhibitory concentrations (MICs) of the obtained fractions against Candida albicans, Candida glabrata and Candida tropicalis were determined by the micro-dilution technique and values against Candida spp. ranged from 0.87 to 3.5 mg/mL. The biofilm inhibitory concentrations (IBF) and sustained inhibition (BSI) assays on C. albicans, C. glabrata and C. tropicalis were also investigated. The VFs inhibited biofilm formation up to 0.87 mg/mL for C. albicans, up to 1.75 mg/mL against C. glabrata and up to 0.87 mg/mL against C. tropicalis. The obtained results highlighted the synergistic mechanism of the detected molecules in the prevention of candidosic biofilm formation. 相似文献
146.
Muhammad Ammar Yan Cao Liguo Wang Peng He Huiquan Li 《Research on Chemical Intermediates》2017,43(12):6951-6972
Synthesis of HDC by methoxycarbonylation of HDA with DMC was carried out over the bulk and hybrid heteropoly acid (HPA) catalyst. The catalysts were systematically characterized by XRD, FTIR, SEM and NH3-TPD techniques. The by-products produced in the reaction were identified and a possible reaction pathway was proposed based on the by-products analysis. The performances of bulk and hybrid HPA catalysts were evaluated. The H4[SiW12O40] catalyst revealed high performance compared with other catalysts and its high performance was attributed to its acidic properties. Effects of reaction parameters and reusability of the H4[SiW12O40] catalyst were also investigated. Under the optimized reaction conditions, HDA conversion reached 93.2% with 64.8% HDC selectivity and only 3.8% by-product selectivity. Moreover, a possible reaction mechanism was proposed for the synthesis of HDC over H4[SiW12O40] catalyst. 相似文献
147.
148.
Brandenburg G Cinabro D Liu T Saulnier M Wilson R Yamamoto H Bergfeld T Eisenstein BI Ernst J Gladding GE Gollin GD Palmer M Selen M Thaler JJ Edwards KW McLean KW Ogg M Bellerive A Britton DI Hyatt ER Janicek R MacFarlane DB Patel PM Spaan B Sadoff AJ Ammar R Baringer P Bean A Besson D Coppage D Copty N Davis R Hancock N Kotov S Kravchenko I Kwak N Kubota Y Lattery M Momayezi M Nelson JK Patton S Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Ling Z Mahmood AH O'Neill JJ Severini H Sun CR 《Physical review letters》1995,75(21):3804-3808
149.
Bergfeld T Eisenstein BI Ernst J Gladding GE Gollin GD Johnson E Karliner I Palmer M Selen M Thaler JJ Edwards KW Bellerive A Britton DI Janicek R MacFarlane DB McLean KW Patel PM Sadoff AJ Ammar R Baringer P Bean A Besson D Coppage D Darling C Davis R Hancock N Kotov S Kravchenko I Kwak N Anderson S Kubota Y Lattery M O'Neill JJ Patton S Poling R Riehle T Smith A Savinov V Alam MS Athar SB Ling Z Mahmood AH Severini H Timm S Wappler F Anastassov A Blinov S Duboscq JE Fulton R Fujino D Gan KK 《Physical review letters》1996,77(22):4503-4507
150.
The reaction of 2-alkyl-4,6-bistrichloromethyl-symm-triazines containing higher alkyl groups with ammonia or aliphatic amines results, depending on the reaction conditions, in the replacement of one or both trichloromethyl groups. On heating these symm-triazines with aqueous ammonia or dimethylamine, 2-oxo-4-amino-6-alkyl-1(3)H-symm-triazines are obtained.For communication 2, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1557–1563, November, 1985. 相似文献