Boolean sums of sets of certain designs

In this note the author applies Boolean sum operation on sets of certain designs to get new series of designs.     

Numerical studies of slow viscous rotating flow past a sphere. II

The Navier–Stokes equations, which are the governing equations for a steady, viscous, incompressible fluid rotating about the z-axis with angular velocity ω, are linearized using the Oseen approximation. Two parameters, namely the Reynolds number Re = Ua/v and Re_ω = 2ωa²/v (the Reynolds number w.r.t. rotation), enter the linearized equations. These equations are solved by the Peaceman–Rachford ADI method and the resulting algebraic equations are solved by the SOR method. Streamlines are plotted and compared with the Oseen solution for the non-rotating case. The magnitude of the vorticity vector with increasing θ is also plotted.     

Drop formation in aqueous two-phase systems

Extraction using aqueous two-phase systems (ATPSs) is a versatile technique for the downstream processing of various proteins/enzymes. The study of drop formation deals with the fundamental understanding of the behavior of liquid drops under the influence of various external body as well as surface forces. These studies provide a basis for designing of the extractions in column contactors in which liquid drops play a major role. Most of the drop formation studies reported so far is restricted to aqueous-organic systems. ATPSs, differ from aqueous-organic systems in their physical properties. In view of this, an attempt was made to develop a model for drop formation in ATPSs adopting the information available on aqueous-organic systems. In order to validate the model, experiments were performed by using polyethylene glycol (PEG)/salt systems of different phase compositions at various flow rates. At low flow rates the single stage model and at high flow rates the two stage model are able to predict the drop volume during its formation from tip of capillary. The experimental results were found to agree reasonably well with those predicted by the model.     

Concentration and temperature polarization effects during osmotic membrane distillation

Pineapple juice is one of the popular fruit juice due to its pleasant aroma and flavor. Concentration of clarified pineapple juice was carried out by osmotic membrane distillation in a plate and frame membrane module. Concentration and temperature polarization effects are found to have significant role on flux reduction during osmotic membrane distillation process. The contribution of these polarization effects on reduction of the driving force (in turn the flux) at various process conditions such as osmotic agent concentration (2–10 mol/kg (1 molality = 1 mol/kg)), flow rate (25–100 ml/min) of feed and osmotic agent are studied. Concentration polarization has more significant effect on flux reduction when compared to temperature polarization. The experimental fluxes were in good agreement with theoretical fluxes when calculated by considering both concentration and temperature polarization effects. The pineapple juice was concentrated up to a total soluble solids content of 62°Brix at ambient temperature.     

Extraction and Purification of Ipomoea Peroxidase Employing Three-phase Partitioning

Three-phase partitioning (TPP) is a novel separation process used for the extraction and purification of biomolecules. The biomolecules are recovered in a purified form at the interface (precipitate), while the contaminants partition in t-butanol and aqueous phases. Peroxidase from the leaves of Ipomoea palmata was purified by using TPP. The ratio of the crude extract to t-butanol of 1:1 and 30% ammonium sulfate at 37 degrees C resulted in about 160% activity recovery and twofold purification in the aqueous phase of the first cycle of TPP. On subjecting the aqueous phase to the second cycle of TPP, a purification of 18-fold was achieved with about 81% activity recovery. The sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed substantial purification, and the molecular weight of peroxidase was found to be 20.1 KDa. The present study shows a higher degree of purification and activity yield as a primary purification process in comparison with existing literature values, thus demonstrating TPP as an attractive downstream process for the purification of peroxidase.     

Effect of process parameters on transmembrane flux during direct osmosis

Direct osmosis is a non-thermal membrane process employed for the concentration of fruit juices at ambient temperature and atmospheric pressure, thereby maintaining the organoleptic and nutritional properties of fruit juices. In the present study, concentration of pineapple juice by direct osmosis was explored. Aqueous solution of sucrose (0–40%, w/w)–sodium chloride (0–26%, w/w) combination was investigated as an alternative osmotic agent. The sucrose–sodium chloride combination can overcome the drawback of sucrose (low flux) and sodium chloride (salt migration) as osmotic agents during direct osmosis process. The effect of the hydrodynamic conditions in the module and feed temperature (25–45 °C) on transmembrane flux was evaluated. For a range of hydrodynamic conditions studied, it was observed that transmembrane flux increases with Reynolds number. The increase in feed temperature resulted in an increase in transmembrane flux. The pineapple juice was concentrated upto a total soluble solids content of 60 °Brix at ambient temperature. The effect of direct osmosis process on physico-chemical characteristics of pineapple juice was also studied. The ascorbic acid content was well preserved in the pineapple juice concentrate by direct osmosis process.     

Incidence matrices and inequalities for combinatorial designs

In this paper we use incidence matrices of block designs and row–column designs to obtain combinatorial inequalities. We introduce the concept of nearly orthogonal Latin squares by modifying the usual definition of orthogonal Latin squares. This concept opens up interesting combinatorial problems and is expected to be useful in planning experiments by statisticians. © 2002 John Wiley & Sons, Inc. J Combin Designs 10: 17–26, 2002     

Pressure dependence of the superconducting state parameters of metallic glass superconductor Mg70Zn30

Explicit expressions have been derived for the volume dependence of electron-phonon coupling strength (λ) and the Coulomb pseudopotential (μ^*) considering the variation of Fermi momentum (κ _F) and Debye temperature (θ _D) with volume. Ashcroft’s model pseudopotential and RPA form of dielectric screening have been used for obtaining pressure dependence of transition temperature (T _C) and the logarithmic volume derivative (Φ) of the effective interaction strength (N ₀ V) for metallic glass superconductor Mg₇₀Zn₃₀. It has been observed that T _C of the metallic glass Mg₇₀Zn₃₀ decreases rapidly with increase of pressure and the superconducting phase disappears at about 30% decrease of volume, for which the μ^* curve shows a minimum and an elbow is formed in the Φ graph.     

Reverse Micellar Extraction of β-Galactosidase from Barley (Hordeum vulgare)

The reverse micellar system of sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane was used for the extraction and primary purification of beta-galactosidase (EC 3.2.1.23) from the aqueous extract of barley (Hordeum vulgare) for the first time. The process parameters such as the concentration of the surfactant, the volume of the sample injected, and its protein concentration, pH, and ionic strength of the initial aqueous phase for forward extraction, buffer pH, and salt concentration for back extraction are varied to optimize the extraction efficiency. Studies carried out with both phase transfer and injection mode of reverse micellar extraction confirmed the injection mode to be more suitable for beta-galactosidase extraction. The extent of reverse micellar solubilization of proteins increased with an increase in protein concentration of the feed sample. However, back extraction efficiency remained almost constant (13-14.4%), which indicates the selectivity of AOT reverse micelles for a particular protein under given experimental conditions. beta-Galactosidase was extracted with an activity recovery of 98.74% and a degree of purification of 7.2-fold.