Application of aeration-assisted homogeneous liquid-liquid microextraction procedure using Box-Behnken design for determination of curcumin by HPLC

A simple, efficient, and rapid sample preparation method based on aeration-assisted homogeneous liquid-liquid microextraction was developed for determination of curcumin in food samples by high-performance liquid chromatography. The centrifuge step has been eliminated in this procedure. The effects of some variables, such as pH, volume of extraction solvent, extraction time, and salt effect, were studied through a Box-Behnken design method. Under the optimum conditions, calibration curves of curcumin were linear in the range of 0.08-4000 μg/mL with R2  = 0.997. Limit of detection and relative standard deviation were 0.019 μg/mL and 3.01%, respectively. The preconcentration factor achieved was 166. The proposed method was successfully applied to determination of curcumin in various food samples.

Structure and Oxidation Behavior of Nickel Nanoparticles Supported by YSZ(111)

Nickel nanoparticles supported by the yttria-stabilized zirconia (111) surface show several preferential epitaxial relationships, as revealed by in situ X-ray diffraction. The two main nanoparticle orientations are found to have their [111] direction parallel to the substrate surface normal and ∼41.3 degrees tilted from this direction. The former orientation is described by a cube-on-cube stacking at the oxide-metal interface and the latter by a so-called coherent tilt strain-relieving mechanism, which is hitherto unreported for nanoparticles in literature. A modified Wulff construction used for the 111-oriented particles results in a value of the adhesion energy ranging from 1.4 to 2.2 Jm², whereby the lower end corresponds to more rounded particles and the upper to relatively flat geometries. Upon oxidation at 10^-3 Pa of molecular oxygen and 673 K, a NiO shell forms epitaxially on the [111]-oriented particles. Only a monolayer of metallic nickel of the top (111) facets oxidizes, whereas the side facets seem to react more severely. An apparent size increase of the remaining metallic Ni core is discussed in relation to a size-dependent oxidation mechanism, whereby smaller nanoparticles react at a faster rate. We argue that such a preferential oxidation mechanism, which inactivates the smallest and most reactive metal nanoparticles, might play a role for the long-term degradation of solid oxide fuel cells.

Microwave-assisted of dispersive liquid-liquid microextraction and spectrophotometric determination of uranium after optimization based on Box-Behnken design and chemometrics methods

In this study an analytical procedure based on microwave-assisted dispersive liquid-liquid microextraction (MA-DLLME) and spectrophotometric coupled with chemometrics methods is proposed to determine uranium. In the proposed method, 4-(2-pyridylazo) resorcinol (PAR) is used as a chelating agent, and chloroform and ethanol are selected as extraction and dispersive solvent. The optimization strategy is carried out by using two level full factorial designs. Results of the two level full factorial design (2(4)) based on an analysis of variance demonstrated that the pH, concentration of PAR, amount of dispersive and extraction solvents are statistically significant. Optimal condition for three variables: pH, concentration of PAR, amount of dispersive and extraction solvents are obtained by using Box-Behnken design. Under the optimum conditions, the calibration graphs are linear in the range of 20.0-350.0 ng mL(-1) with detection limit of 6.7 ng mL(-1) (3δB/slope) and the enrichment factor of this method for uranium reached at 135. The relative standard deviation (R.S.D.) is 1.64% (n=7, c=50 ng mL(-1)). The partial least squares (PLS) modeling was used for multivariate calibration of the spectrophotometric data. The orthogonal signal correction (OSC) was used for preprocessing of data matrices and the prediction results of model, with and without using OSC, were statistically compared. MA-DLLME-OSC-PLS method was presented for the first time in this study. The root mean squares error of prediction (RMSEP) for uranium determination using PLS and OSC-PLS models were 4.63 and 0.98, respectively. This procedure allows the determination of uranium synthesis and real samples such as waste water with good reliability of the determination.

The effect of fennel essential oil on uterine contraction as a model for dysmenorrhea, pharmacology and toxicology study

Increasing the ectopic uterine motility is the major reason for primary dysmenorrhea. This motility is the basis for several symptoms including for pain is the main complaints of patients with primary dysmenorrhea. There are several mechanisms, which initiate dysmenorrhea. Therefore, different compounds can be employed to control its symptoms. In long-term therapy, combination of oestrogens and progestins may be useful. In short-term therapy, dysmenorrhea sometimes non-steroidal anti-inflammatory drugs (NSAIDs) are used. Most of NSAIDs in long-term therapy show severe adverse effects. In an attempt to find agents with less adverse effect the fennel essential oil (FEO) was chosen for this investigation. In this article, effects of FEO on the uterine contraction and estimation of LD(50) in rat were described. For assessment of pharmacological effects on the isolated rat uterus, oxytocin (0.1, 1 and 10 mu/ml) and prostaglandin E(2) (PGE(2)) (5x10(-5) M) were employed to induce muscle contraction. Administration of different doses of FEO reduced the intensity of oxytocin and PGE(2) induced contractions significantly (25 and 50 microg/ml for oxytocin and 10 and 20 microg/ml PGE(2), respectively). FEO also reduced the frequency of contractions induced by PGE(2) but not with oxytocin. LD(50) of FEO was obtained in the female rats by using moving average method. The estimated LD(50) was 1326 mg/kg. No obvious damage was observed in the vital organs of the dead animals.