Calculation of terminal velocity in transitional flow for spherical particle

The terminal velocity has been widely used in extensive fields, but the complexity of drag coefficient expression leads to the calculation of terminal velocity in transitional flow （1 〈 Re ≤ 1000） with much more difficulty than those in laminar flow （Re ≤ 1） and turbulent flow （Re ≥ 1000）. This paper summarized and compared 24 drag coefficient correlations, and developed an expression for calculating the terminal velocity in transitional flow, and also analyzed the effects of particle density and size, fluid density and viscosity on terminal velocity. The results show that 19 of 24 previously published correlations for drag coefficient have good prediction performance and can be used for calculating the terminal velocity in the entire transitional flow with higher accuracy. Adapting two dimensionless parameters （w＊, d＊）, a proposed explicit correlation, w＊=-25.68654 × exp （-d＊/77.02069）＋ 24.89826, is attained in transitional flow with good performance, which is helpful in calculating the terminal velocity.

Theoretical and experimental study on lipophilicity and wound healing activity of ginger compounds

Objective:To correlate the chromatographic and computational method to calculate lipophilicity of selected ginger compounds and to observe the effects of log P on wound healing.Methods:Mixtures of acetonitrile and water with acetonitrile content between 95%and 50%v/v in 5%increments were kept separately in 10 different chromatographic chambers,saturated with solvent for 2 h.Spots were observed under UV light atλ=254 nm p-anisaldehyde used as a spraying reagent Theoretical calculation was done using the Alogps 2.1 online program at www.vcclab.org/lab/alogps.For percentage wound contraction,five groups of animal(mice)(25-30 g)of either sex were selected.Wound were created on dorsal surface of animals using toothed forceps,scalpel and pointed scissors.The wound areas were calculated using vernier caliper.After making wound mice were orally administered 35 mg/kg 6-shogoal,6-gingerol,8-gingerol and 10-gingerol respectively.Croup E as the control group received tap water.Results:The Iipophilicity values determined in thin layer chromatography were correlated with the theoretically calculated various log P by linear regression analysis.Significant correlations were found between log P values calculated by software program and the experimental reversedphase thin-layer chromatography data.Order of wound healing property of ginger compounds is directly dependent on lipophilieity i.e.more lipophilic compound has highest activity.Conclusions:Experimentally determined lipophilieity(R_(MO))values were correlated with log P determined by software's and found satisfactory.Lipophilieity(R_(MO)is a useful parameter for the determination and prediction of biological activity of ginger compounds.

A method for calculating the seabed acousticattenuation coefficient in shallow water

In this paper, a method of effectively calculating the acoustic attenuation coefficient for a fluid seabed with high sound speed is presented. The method is formulated based on the fact that the fractional part of the attenuation coefficient contributed by the water column varies slowly with different normal modes. One of the advanages of the method is that it can remove the effects of the water column absorption. Furthermore, the method can be used to invrse the seabed acoustic attenuation coefficient in a wider frequency range of ≤ 2 kHz than the conventional methods (f ≤200 Hz).