Digital holographic scanning of large objects using a rotating optical slab

Simple optical glass is used in digital holographic set up to scan and record holograms of a large object. Dimension of the object is such that it does not satisfy sampling theorem. Experimental results and calculations illustrate that an optical slab can be used to scan the surface of the large object by this method. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 16, 258–261, 2006     

Oscillatory instabilities of the liquid and mushy layers during solidification of alloys under rotational constraint

Summary Linear flow instabilities due to oscillatory disturbances of the liquid and mushy regions during solidification of binary alloys are investigated under a rotational constraint where the rotation axis is inclined to gravity vector. Results of stability analyses and numerical computations for a preferred centrifugal mode of general oscillatory disturbances at zero and non-zero rotation rates are determined which provide information about the preference of oscillatory flow and its role on the solidification system as modified by the rotational effects. The main results are due to a preferred oscillatory mode of convection which is more significant for non-zero rotation case and is restricted mostly to the mushy region. The preferred oscillatory mode of convection is a traveling wave in the presence of rotation, but it is a standing wave in the absence of rotation. The results for different Prandtl numbers indicate that the freckles formation tendency for metallic alloys is less than that for aqueous solutions. Freckles are imperfections that reduce the quality of the solidified materials.     

Effect of heat treatment and solution preparation procedure on colloidal stability of whey protein sour cherry beverage

In this study, a whey protein sour cherry beverage was prepared using whey protein concentrate, sour cherry concentrate, Angum gum, water and sugar as initial ingredients. Whey protein concentrate and gum solutions were prepared by four methods. Heat treatment of the solutions led to denaturation of proteins, a change in the solubility of proteins and sediment formation. Our results showed that denaturation of proteins made the peptide fragments of the proteins to bind the gum, thus preventing the separation of the serum.     

Theoretical investigation of interaction between Gatifloxacin and DNA: Implications for anticancer drug design

This study is an attempt to have a better understanding of the physicochemical interaction between a novel anticancer drug, Gatifloxacin (GTFX) and its biological receptor, DNA. The eventual purpose is to design drugs which interact more with DNA. Considering the physicochemical properties of the drug as well as the mechanism by which it interacts with DNA, it should eventually allow the rational design of novel anticancer or antiviral drugs. Molecular modeling on the complex formed between Gatifloxacin and DNA presented the full ability of the drug for participating in the formation of a stable intercalation site. Besides, the molecular geometries of Gatifloxacin (GTFX) and the DNA bases (Adenine, Guanine, Cytosine and Thymine) were optimized with the aid of B3LYP/6-31G? method. The properties of the isolated intercalator and its stacking interactions with the adenine?thymine (AT) and guanine?cytosine (GC) nucleic acid base pairs, were studied using DFTB method, (an approximate version of the DFT method) that was extended to cover the London dispersion energy. The B3LYP/6-31G? stabilization energies of the intercalator?base pair complexes were found to be ? 26.99 and ? 37.62 kcal/mol for AT?GTFX and GC?GTFX, respectively. It was completed that the dispersion energy and the electrostatic interaction contributed to the stability of the intercalator?DNA base pair complexes.     

Comparison of surface functional groups and metal uptake efficiency of rice husk harvested from different climatic zones

Rice husk (RH) is a very effective natural adsorbent for fast removal of heavy metal cations from water solutions. Application of RH for removal of some heavy metal ions, such as Ni, Zn, Mn, Co, Cu, Pb and Cd from water solutions has been studied and different maximum adsorption capacities and a variety of optimized conditions were reported in the literature. In this work, the efficiency of RH harvested from different climatic regions was studied. For this proposal, different RH samples were collected from three different climatic regions of Iran (nominated as RH1 to RH3); their removal efficiencies of heavy metal cations of Ni(2+), Cu(2+) and Cd(2+) were investigated and compared. The adsorption data at optimum conditions could be assessed well by both Langmuir and Freundlich models. Statistical analysis of the results of adsorption isotherms showed that different RH samples have different efficiencies in uptake of these heavy metal ions. The RH samples were characterized using Fourier transform infrared spectroscopy and Boehm titration, which indicated that amounts of functional groups differed between RHs that are grown in different climatic conditions.     

Direct resonance analysis and modeling for a turbulent boundary layer over a corrugated surface

Summary Effects of surface corrugation on turbulent flow in a boundary layer are studied using a model based on the direct resonance theory. The induced mean flow due to weakly nonlinear waves, superimposed on the mean and fluctuating components of turbulence, is determined. The mean turbulent flow is affected by the surface corrugation throughout the boundary layer. The corrugated surface generates higher harmonics and affects the streamwise vortices generated by the waves superimposed on turbulence whose mean flow includes secondary induced mean flow components due to the corrugation.     

Computer-aided design of the effects of Fe2O3 nanoparticles on split tensile strength and water permeability of high strength concrete

In the present paper, two models based on artificial neural networks and genetic programming for predicting split tensile strength and percentage of water absorption of concretes containing Fe₂O₃ nanoparticles have been developed. To build these models, training and testing of the network by using experimental results from 144 specimens produced with 16 different mixture proportions were conducted. The data used in the multilayer feed forward neural networks models and input variables of genetic programming models have been arranged in a format of eight input parameters that cover the cement content, nanoparticle content, aggregate type, water content, the amount of superplasticizer, the type of curing medium, age of curing and number of testing try. According to these input parameters, in the two models, the split tensile strength and percentage of water absorption values of concretes containing Fe₂O₃ nanoparticles were predicted. The training and testing results in the neural network and genetic programming models have shown that every two models are of strong potential for predicting the split tensile strength and percentage of water absorption values of concretes containing Fe₂O₃ nanoparticles. Although neural network has predicted better results, genetic programming is able to predict reasonable values with a simpler method rather than neural network.     

Evaluation of Vitreous and Devitrifying Enamels as Hot Forming Lubricants for Aluminum AA5083 Alloy

The adhesion of aluminum to tool surfaces during the hot forming of sheet aluminum alloys presents challenging tribological problems. Graphite and boron nitride are commonly used as aluminum adhesion mitigating solid lubricants for hot forming processes, but lubricant breakdown in high-stress areas, such as corners and bends, remains an issue compromising the quality of the formed parts as well as the tool life. Low-melting temperature enamels may provide an affordable and easy to apply alternative. In this study, vitreous (amorphous glass) and devitrifying (two phase crystalline glass) layers were deposited on the surface of sheet aluminum samples with a sedimentation technique. Enamel lubrication was effective in preventing aluminum transfer to the steel counterface. Hence, the prospect exists for the use of these enamels as aluminum workpiece lubricants in hot forming operations. This article was presented at Materials Science & Technology 2007, Automotive and Ground Vehicles Symposium held September 16-20, 2007, in Detroit, MI.     

Buoyancy and surface tension driven flows in float zone crystal growth with a strong axial magnetic field

The buoyancy driven flow due to the temperature gradient in the melt of a float zone and the surface tension driven flow due to the non-uniform temperature distribution along the free surface of the zone are studied in the presence of a strong axial magnetic field. The non-cylindrical shape of the zone is found to have a profound effect on the melt motion. The results indicate that the regions near the free surface are controlled mainly by the thermocapillarity, while the inner region is dominated by the buoyancy driven flow. Some implications for the mass transport of dopants in the molten float zone are discussed.