Supramolecular assembly in the chiral N-carbamoyl compound 2-ureido-pentanedioic acid

The compound 2-ureido-pentanedioic acid was synthesized and characterized by FT-IR and NMR spectra. Its molecular structure was solved by single crystal X-ray diffraction. In the title compound, C₆H₁₀N₂O₅, the chiral structure is stabilized by intermolecular O–H···O and N–H···O hydrogen bonds in a supramolecular assembly formed by infinite chains parallel to the bc plane with graph set C(4) connected by amide-acid dimers R²₂(8) into a three-dimensional network.     

Determination of isoflavones in ready-to-feed soy-based infant formula

An alkaline hydrolysis/liquid chromatography (LC) method was developed for determination of isoflavones in ready-to-feed soy-based infant formula. The method consists of a 15 min methanol extraction, 10 min alkaline hydrolysis, HCl neutralization, gravity filtration, aqueous dilution, and 50 min LC analysis with UV detection at 262 and 250 nm to quantify 6 isoflavone analytes: daidzin, glycitin, genistin, daidzein, glycitein, and genistein. The concentration averages for 10 commercial batches (microg aglycone/g formula) were daidzein, 6.12 +/- 1.23; glycitein, 1.19 +/- 0.16; genistein, 12.8 +/- 2.35; and total, 20.1 +/- 3.61. Validation experiments demonstrated extraction completion and analyte stability to alkaline hydrolysis. Spike recoveries ranged from 97.6 to 104.1%, and a series of accuracy assessments showed that isoflavone concentration determined by the method was within 5% of the true value. The relative standard deviation values for repeatability ranged from 0.4 to 2.2% (n = 10), and from 0.3 to 2.7% (n = 4) for intermediate precision. Isoflavone peak purity was verified by comparing sample and standard peak area ratios (262/250 nm). The limits of detection and quantitation (microg/ formula) ranged from 0.02 to 0.05 and 0.08 to 0.18 microg/g, respectively. The difference between our concentrations and those reported by others in 1995-1998 is attributable to the well-established seasonal variation in soybean isoflavone levels. Although the method was applied exclusively to ready-to-feed formula in the present study, it is equally suitable for powder and concentrated liquid infant formulas.     

Finsler metrics of scalar flag curvature with special non-Riemannian curvature properties

In this paper, we study Finsler metrics of scalar flag curvature. We find that a non-Riemannian quantity is closely related to the flag curvature. We show that the flag curvature is weakly isotropic if and only if this non-Riemannian quantity takes a special form. This will lead to a better understanding on Finsler metrics of scalar flag curvature.      

Cheeger-gromoll type metrics on the (1,1)-tensor bundles

Using a Riemannian metric on a differentiable manifold, a Cheeger-Gromoll type metric is introduced on the (1,1)-tensor bundle of the manifold. Then the Levi-Civita connection, Riemannian curvature tensor, Ricci tensor, scalar curvature and sectional curvature of this metric are calculated. Also, a para-Nordenian structure on the the (1,1)-tensor bundle with this metric is constructed and the geometric properties of this structure are studied.     

On a class of Riemannian metrics arising from Finsler structures

On the slit tangent bundle of Finsler manifolds, we introduce a class of metrics and study the relation between Levi-Civita connection, Vaisman connection, vertical foliation, and Reinhart spaces. We show that the Levi-Civita and the Vaisman connections induce the same connections in the structural bundle if and only if the base manifold is Landsbergian. Moreover every foliated Reinhart manifold reduces to a Riemannian manifold.     

Conjugate natural convection of non-Newtonian hybrid nanofluid in wavy-shaped enclosure

The present study concerns the modelization and numerical simulation for the heat and flow exchange characteristics in a novel configuration saturated with a nonNewtonian Ag-MgO hybrid nanofluid. The wavy shaped enclosure is equipped with onequarter of a conducting solid cylinder. The system of equations resulting from the mathematical modeling of the physical problem in its dimensionless form is discretized via the higher-order Galerkin-based finite element method(GFEM). The dependency of vario...