A new acylated flavonoid tetraglycoside with anti-inflammatory activity from Tipuana tipu leaves

A new acylated kaempferol glycoside, kaempferol 3-O-α-l-rhamnopyranosyl-(1 → 6)-O-[β-d-glucopyranosyl-(1 → 2)-4-O-acetyl-α-l-rhamnopyranosyl-(1 → 2)]-β-d-galactopyranoside, has been isolated from the leaves of Tipuana tipu (Benth.) Lillo growing in Egypt, along with three known flavonol glycosides, kaempferol 3-O-rutinoside, quercetin 3-O-rutinoside (rutin) and kaempferol 3-O-[α-l-rhamnopyranosyl-(1 → 6)]-[α-l-rhamnopyranosyl-(1 → 2]-β-d-glucopyranoside. Structure elucidation was achieved through different spectroscopic methods. Structure relationship with anti-inflammatory activity using carrageenin-induced rat paw oedema model is discussed.     

Electron Ionization Mass Spectra of Organophosphorus Compounds Part I: The Mass Fragmentation Pathways of Cyclic α-Aminophosphonates Monoester Containing 1,2,4-Triazinone Moiety

Abstract

The electron impact induced fragmentation reactions of 3-(4-chlorophenyl)-3,4- dihydro-2-ethoxy-2-oxido-7-methyl-2H,6H-[1,2,4]triazino[4,3-e][1,4,5,2]thiadiazaphosphin in-6-one (1), 3,7-dimethyl-2-ethoxy-2-oxido-1,2,3,4-tetrahydro-6H-[1,2,4]triazino[4,3-b][1,2,4,5]triazaphosphinin-6-one (2), and 9-amino-3,7-dimethyl-4-ethoxy-4-oxido-2,3,4,9-tetrahydro-8H-[1,2,4]triazino[3,2-c][1,2,4,5]triazaphosphinin-8-one (3) are presented and compared. The 1,2,4-triazine rings have almost identical fragmentation routes. The 1,2,4-triazine rings are rather stable relative to the phosphorus rings. Therefore, fragmentation of the phosphorus rings is more favorable for the compounds than the stable 1,2,4-triazine rings.     

Flow control using bifrequency motion

We used a second-order approximation for the periodic lift coefficient of a circular cylinder under monofrequency and bifrequency cross-flow motions. Two lock-in modes exist under monofrequency fundamental (i.e., near the Strouhal number) motion. In the first mode, the work is done by the flow on the cylinder, whereas in the second mode the work is done by the cylinder on the flow. Under monofrequency superharmonic (i.e., near three times the Strouhal number) motion, the work is always done on the flow. We then replaced the monofrequency motions by a bifrequency one, consisting of a fundamental term combined with a small-magnitude superharmonic term. We examined the effect of the magnitude and phase of the superharmonic motion term on the two modes of lock-in which we obtained when only the fundamental motion term is applied, considering two different frequencies that belonged to the two lock-in modes. Under the bifrequency motion, the work can be done on the flow or on the cylinder. This can be controlled using the superharmonic motion term, even when its magnitude is 5% of magnitude of the fundamental motion term. Other flow variables, such as the magnification of the lift, can be remarkably altered through the added superharmonic motion term. The phase of the third superharmonic lift-coefficient component relative to the fundamental one is the most responsive variable to the phase of the superharmonic motion component relative to the fundamental one.     

NMR study of Li+ ion dynamics in the perovskite Li(3x)La(1/3-x)NbO3

(7)Li and (6)Li nuclear magnetic resonance (NMR) experiments are carried out on the perovskite Li(3x)La(1/3-x)NbO(3). The results are compared to those obtained on the titanate Li(3x)La(2/3-x)TiO3 (LLTO) in order to investigate the effect, on the lithium ion dynamics, of the total substitution of Nb(5+) for Ti(4+) in the B-site of the ABO(3) perovskites. The XRD patterns analysis reveals that this substitution leads to a change in the distribution of the La(3+) ions in the structure. La(3+) ions distribution is very important, in regard to ionic conductivity, because these immobile ions can be considered as obstacles for the long-range Li+ motion. If compared to the titanates, the compounds of the niobate solid solution have a bigger unit cell volume, a smaller number of La(3+) ions, and a higher number of vacancies. These should favor the motion of the mobile ions into the structure. This is not experimentally observed. Therefore, the interactions between the mobile species and their environment greatly influence their mobility. (7)Li and (6)Li NMR relaxation time experiments reveal that the Li relaxation mechanism is not dominated by quadrupolar interaction. (7)Li NMR spectra reveal the presence of different Li+ ion sites. Some Li+ ions reside in an isotropic environment with no distortion, some others reside in weakly distorted environments. T(1), T(1)(rho), and T(2) experiments allow us to evidence two motions of Li+. As in LLTO, T(1) probes a fast motion of the Li+ ions inside the A-cage of the perovskite structure and T(1)(rho) a slow motion of these ions from A-cage to A-cage. At variance with what has been observed in LLTO, these different Li+ ions can be differentiated through the spin-lattice relaxation times, T(1) and T(1)(rho), as well as through the transverse relaxation time, T(2).     

A new pregnane glycoside from Gomphocarpus fruticosus growing in Egypt

Phytochemical investigation of Gomphocarpus fruticosus (L.) Ait. of Egyptian origin afforded the new pregnane glycoside lineolon-3-O-[β-D-oleandropyranosyl-(1–4)-β-D-cymaropyranosyl-(1–4)-β-D-cymaropyranoside], along with six known compounds. The structures of the isolated compounds were elucidated on the basis of extensive spectroscopic evidences derived from 1D, 2D NMR experiments, mass spectrometry and by comparing their physical and spectroscopic data to literature. These included the triterpenoids 3β-taraxerol, 3β-taraxerol acetate and betulinic acid, which are identified for the first time in G. fruticosus and the cardenolides uzarigenin, gomphoside and calotropin.     

One-way and two-way couplings of CFD and structural models and application to the wake-body interaction

The current study focuses on the wake-body interaction of a circular cylinder, whose transverse free vibration is modeled by a mass-spring-damper system coupled to a computational fluid dynamics (CFD) model for the flow and wake. We first simulate the free vibration of the elastically-mounted cylinder and the wake, and analyze the transverse load it exerts on the cylinder and its phase with the vibration. We vary the damping by three orders of magnitude and examine the difference in the wake-body interaction for slightly-damped and highly-damped systems. We then use the spectral properties of the free vibration and use them to construct two different types of forced vibrations: one consists only of the fundamental component of the free vibration, and the other accounts for all spectral properties of it. We compare the wake load for each type to that corresponding to the free vibration. The forced vibrations correspond to a one-way coupling and the information is communicated from the CFD model to the structural model, whereas the free vibration corresponds to a two-way coupling of the models. By comparing the spectral properties of the wake load, including the phase relation of its components with the vibration, which we obtained for the free vibration and for the equivalent forced vibration, we identify the effects of the wake feedback. The findings show that a forced vibration does not reproduce exactly the wake load at small and intermediate levels of structural damping. As the damping increases, the vibration changes from being in-phase with the wake load to being 90° out-of-phase with it, corresponding to two different wake states, and the forced vibration gives wake load that is very close to the one occurring in the case of full wake-body interaction.     

Structural studies and mechanical properties of some borate glasses doped with different alkali and cobalt oxides

Mixed alkali borate glasses doped with CoO, have been prepared by the melt quenching technique. Elastic properties and FT-IR spectroscopic studies have been employed to study the role of CoO and the mixed alkali effect on the structure of the investigated glass system. Elastic properties and Debye temperature have been investigated using sound wave velocity measurements at 4 MHz at room temperature. The density, molar volume and glass transition temperatures were employed to investigate the structure of these glasses. Infrared spectra of these glasses revealed that the borate network is affected by the increase in the concentration of CoO content and the mixed alkali oxides. These results are interpreted in terms of the change in the topology of these glass structures. The elastic moduli are observed to increase with the increase of CoO content due to the increased average bond connectivity.     

Ultrasonic,FTIR and thermal investigations of SiO2–Na2O–CaO–P2O5 glasses doped with CeO2

The longitudinal and shear ultrasonic wave velocities for different compositions of SiO₂–Na₂O–CaO–P₂O₅ glasses were measured at room temperature (305 K) using a pulse-echo method at a frequency of 4 MHz. The elastic moduli, Poisson's ratio, microhardness, Debye temperature and other ultrasonic parameters were obtained from experimental data and analyzed using bond compression theory. By calculating the number of network bonds per unit volume, the average stretching constant, and the average ring size, information about the structure of the glass can be deduced. Structural changes after doping with CeO₂ were investigated by FTIR spectroscopy, and by measurements of the thermal expansion coefficient, glass transition and softening temperature to throw more light on the characterization of these glasses.