Detecting Chirality in Mixtures Using Nanosecond Photoelectron Circular Dichroism

We report chirality detection of structural isomers in a gas phase mixture using nanosecond photoelectron circular dichroism (PECD). Combining pulsed molecular beams with high-resolution resonance enhanced multi-photon ionization (REMPI) allows...

Research on the Coupled Water–Soil SPH Algorithm Improvement and Application Based on Two-phase Mixture Theory

An improved water–soil coupling algorithm was proposed based on the two-phase mixture theory within the framework of smoothed particle hydrodynamics (SPH). In this algorithm, the buoyant density was considered in saturated soil and the stress of two phases was completely exfoliated with the Terzaghi’s effective stress principle. Then the interaction between water and soil was only constituted by viscous drag force. The proposed algorithm was validated by several numerical tests to effectively solve a series of numerical problems caused by the truncation of the kernel approximation on the interface between submerged soil and water, and it can also be a feasible measure to simulate underwater soil excavation problems without drainage and underwater landside problems. Meanwhile, combined with frictional sliding contact algorithm, the interaction between water/soil and structure which was considered as rigid can be effectively modeled, and the calculated contact forces acting on the structure are more accurate. Furthermore, this improved algorithm can be applied to deal with large deformation problems involving complex water–soil–structure interaction in hydraulic and geotechnical engineering such as underwater excavation, shield dig, caisson sinking and other practical engineering problems. It is also significant to engineering design and the improvement of construction level.

Two-phase mixture of iron–nickel–silicon alloys in the Earth’s inner core

The Earth’s inner core comprises iron-nickel alloys with light elements. However, there is no clarity on the phase properties of these alloys. Here we show phase relations and equations of state of iron–nickel and iron–nickel–silicon alloys up to 186 gigapascals and 3090 kelvin. An ordered derivative of the body-centred cubic structure (B2) phase was observed in these alloys. Results show that nickel and silicon influence the stability field associated with the two-phase mixture of B2 and hexagonal close-packed phases under core conditions. The two-phase mixture can give the inner core density of the preliminary reference Earth model. The compressional wave velocity of the two-phase mixture under inner core conditions is consistent with that of the preliminary reference Earth model. Therefore, a mixture of B2 and hexagonal close-packed phases may exist in the inner core and accounts for the seismological properties of the inner core such as density and velocity deficits.

Numerical Prediction of Two-Phase Flow through a Tube Bundle Based on Reduced-Order Model and a Void Fraction Correlation

Predicting the void fraction of a two-phase flow outside of tubes is essential to evaluate the thermohydraulic behaviour in steam generators. Indeed, it determines two-phase mixture properties and affects two-phase mixture velocity, which enable evaluating the pressure drop of the system. The two-fluid model for the numerical simulation of two-phase flows requires interaction laws between phases which are not known and/or reliable for a flow within a tube bundle. Therefore, the mixture model, for which it is easier to implement suitable correlations for tube bundles, is used. Indeed, by expressing the relative velocity as a function of slip, the void fraction model of Feenstra et al.and Hibiki et al. developed for upward cross-flow through horizontal tube bundles is introduced and compared. With the method suggested in this paper, the physical phenomena that occur in tube bundles are taken into consideration. Moreover, the tube bundle is modelled using a porous media approach where the Darcy–Forchheimer term is usually defined by correlations found in the literature. However, for some tube bundle geometries, these correlations are not available. The second goal of the paper is to quickly compute, in quasi-real-time, this term by a non-intrusive parametric reduced model based on Proper Orthogonal Decomposition. This method, named Bi-CITSGM (Bi-Calibrated Interpolation on the Tangent Subspace of the Grassmann Manifold), consists in interpolating the spatial and temporal bases by ITSGM (Interpolation on the Tangent Subspace of the Grassmann Manifold) in order to define the solution for a new parameter. The two developed methods are validated based on the experimental results obtained by Dowlati et al. for a two-phase cross-flow through a horizontal tube bundle.

Validation and Quantification of Domperidone in Spiked Plasma Matrix Using Reversed Phase HPLC-UV Method

Pharmacokinetics studies of domperidone generally analyze plasma matrix samples. The present work aimed to develop and validate a rapid and simple reversed phase-HPLC method for quantifying domperidone in plasma matrices. The chromatographic method implemented: 1. Luna Phenomenex® C18 (250 mm × 4.6 mm i.d; 5 µm) column, 2. isocratic mobile phase mixture of phosphate buffer 0.02 M:acetonitrile (70:30, v/v) with a flow rate of 1 mL/min, 3. UV detection at 285 nm. Domperidone and propranolol hydrochloride (as internal standard) were extracted from the deproteinated plasma sample. The method linearity was 0.998 in the range concentration of 15–200 ng/mL. The percentage of accuracy error was between -8.49–4.31%, while the percentage coefficient variation of precision ranged between 5.11–14.24%. This proposed method was simple, rapid (separation time less than 10 min), and selective. The validation parameters responses satisfied the method's requirements to determine domperidone in a plasma sample.