Relaxant activity of different fractions of fruits of Rosa moschata J.

The current work is an attempt to know that in which fraction(s) the relaxant constituents of Rosa moschata concentrate. Crude methanolic extract of Rosa moschata was prepared as per our reported procedure. Sub fractions of methanol extract were extracted with different solvents in increasing order of polarity i.e. n-hexane > chloroform > ethyl acetate > n-butanol > residual aqueous fractions. Different concentrations (0.01, 0.03, 0.1, 0.3, 1, 3, 5 and 10 mg/ml) of the fractions were tested on spontaneous contractions and KCl induced contractions on rabbits' jejunal preparations. Calcium Concentration Response Curves (CCRCs) in the presence and absence of the test fractions using verapamil were constructed to understand its mechanisms. EtOA fraction was more relaxant with EC50 values 0.812±0.149 mg/ml on spontaneous and 2.01±0.08 mg/ml on KCl induced contractions. we also found right shift in its EC50 values expressed as log [Ca++]M values. In presence of 0.3 mg/ml EtOA fraction, its EC50 value was -2.22±0.035 vs control EC50 -2.71±0.21. For n-BuOH fraction, EC50 value was -1.82±0.00 vs control with EC50 -2.28±0.049 at concentration of 0.3 mg/ml. Ethyl acetate fraction of Rosa moschata was more potent and is therefore can be a target for activity guided isolation of calcium channel antagonists.

Investigation of the Dynamic Contact Angle Using a Direct Numerical Simulation Method.

A large amount of residual oil, which exists as isolated oil slugs, remains trapped in reservoirs after water flooding. Numerous numerical studies are performed to investigate the fundamental flow mechanism of oil slugs to improve flooding efficiency. Dynamic contact angle models are usually introduced to simulate an accurate contact angle and meniscus displacement of oil slugs under a high capillary number. Nevertheless, in the oil slug flow simulation process, it is unnecessary to introduce the dynamic contact angle model because of a negligible change in the meniscus displacement after using the dynamic contact angle model when the capillary number is small. Therefore, a critical capillary number should be introduced to judge whether the dynamic contact model should be incorporated into simulations. In this study, a direct numerical simulation method is employed to simulate the oil slug flow in a capillary tube at the pore scale. The position of the interface between water and the oil slug is determined using the phase-field method. The capacity and accuracy of the model are validated using a classical benchmark: a dynamic capillary filling process. Then, different dynamic contact angle models and the factors that affect the dynamic contact angle are analyzed. The meniscus displacements of oil slugs with a dynamic contact angle and a static contact angle (SCA) are obtained during simulations, and the relative error between them is calculated automatically. The relative error limit has been defined to be 5%, beyond which the dynamic contact angle model needs to be incorporated into the simulation to approach the realistic displacement. Thus, the desired critical capillary number can be determined. A three-dimensional universal chart of critical capillary number, which functions as static contact angle and viscosity ratio, is given to provide a guideline for oil slug simulation. Also, a fitting formula is presented for ease of use.