Synthesis and Investigation of Surface Active Properties of Counterion Coupled Gemini Surfactants

Three counterion coupled gemini (cocogem) surfactants in the series 1,6‐bis(N,N‐alkyldimethylammonium) adipate, referred as n‐6‐n (n = 12, 14, 16), were synthesized, purified and characterized by ¹H NMR and ¹³C NMR. Their physicochemical properties were investigated by electrical conductivity and surface tension measurements. The degree of ionization, critical micelle concentration (CMC), surface excess at the air/solution interface (Γ_max), minimum area per surfactant molecule at the air/solution interface (A_min), surface tension at the CMC (γ_CMC), and pC₂₀ (negative log of the surfactant molar concentration, required to reduce the surface tension of water by 20 mN m^?1) were calculated. Increase in tail length of the surfactants increases the efficiency of surfactants to decrease the surface tension of water. Thermodynamic parameters, viz. molar free energy at the maximum adsorption attained at CMC (G_min), standard Gibb's energy of micellization (), and standard Gibbs energy of adsorption (), were also calculated. The and values show that the monomers were preferred to be adsorbed at the air/water interface and then in the micellar formation in the bulk. Additionally, fluorescence measurements were used to find the aggregation number. Other relevant surface properties (Krafft point, emulsion stability, foaming ability, micellar stability and dye solubilization ability) were also evaluated. These results suggest that with respect to emulsion formation, micellar stability and dye solubilization, the cocogem with a 16‐carbon chain gives better results, producing 89 % more stable foams and shows better aggregational behavior.     

Mathematical modeling of axial crushing of cylindrical tubes

Different aspects of mathematical modeling for the axial crushing of cylindrical tubes with straight fold have been discussed. The variation of circumferential strain during the formation of a fold has been taken into account. The present paper tries to answer questions such as (a) how great is the inside and outside folding, and (b) how the crushing load varies. In the present paper, the influence of the consideration of the conservation of mass on the mathematical formulation has been studied. The results of average and varying circumferential strain have also been compared.     

Soy isoflavone genistein induces cell death in breast cancer cells through mobilization of endogenous copper ions and generation of reactive oxygen species

Scope: Worldwide geographical variation in cancer incidence indicates a correlation between dietary habits and cancer risk. Epidemiological studies have suggested that populations with high isoflavone intake through soy consumption have lower rates of breast, prostate, and colon cancer. Isoflavone genistein in soybean is considered a potent chemopreventive agent against cancer. Although several mechanisms have been proposed, a clear anticancer action mechanism of genistein is still not known. Methods and results: Here, we show that the cytotoxic action of genistein against breast cancer cells involves mobilization of endogenous copper. Further, whereas the copper specific chelator neocuproine is able to inhibit the apoptotic potential of genistein, the molecules which specifically bind iron (desferroxamine mesylate) and zinc (histidine) are relatively ineffective in causing such inhibition. Also, genistein‐induced apoptosis in these cells is inhibited by scavengers of reactive oxygen species (ROS) implicating ROS as effector elements leading to cell death. Conclusions: As copper levels are known to be considerably elevated in almost all types of cancers, in this proof‐of‐concept study we show that genistein is able to target endogenous copper leading to prooxidant signaling and consequent cell death. We believe that such a mechanism explains the anticancer effect of genistein as also its preferential cytotoxicity towards cancer cells.     

Nonstandard analysis of a converging shock wave in a nonideal gas

The problem of propagation of strong plane and converging shock waves in an unsteady inviscid nonideal gas is studied. A nonstandard analysis is used to derive the jump conditions for both shock waves. It is assumed that the jump occurs on an infinitesimal interval and jump functions in the flow parameters are smooth across this interval. The distribution of the flow parameters across the shock wave is expressed in terms of the Heaviside functions. Numerical computation to study the distribution of the flow parameters is performed.     

Lactose hydrolysis from milk/whey in batch and continuous processes by concanavalin A-Celite 545 immobilized Aspergillus oryzae β galactosidase

The present study deals with the immobilization of Aspergillus oryzae β galactosidase on concanavalin A layered Celite 545 as bioaffinity support. The activity yield of crosslinked enzyme was 71%. Michaelis constant, K_m was 2.45 mM and 5.58 mM for soluble and crosslinked adsorbed β galactosidase, respectively. V_max for soluble and crosslinked adsorbed enzyme was 0.52 mM/min and 0.38 mM/min, respectively. Moreover, Ki_app value of crosslinked β galactosidase was 366 × 10^?6 M while its soluble counterpart exhibited lower Ki_app value, 181 × 10^?6 M at 2% galactose concentration. Soluble and immobilized β galactosidase exhibited same pH and temperature optima at pH 4.5 and 50 °C. The crosslinked adsorbed enzyme retained 90% activity after 1 month of storage at 4 °C and 71% activity after its seventh repeated use. Moreover, crosslinked β galactosidase showed greater resistance to product inhibition mediated by glucose and galactose. Crosslinked Con A-Celite adsorbed β galactosidase showed increased efficiency in hydrolyzing lactose from milk and whey in batch processes at 50 °C as compared to the adsorbed and soluble enzyme. The hydrolysis of lactose in the continuous reactors containing crosslinked β galactosidase was 92% and 81% at flow rate of 20 mL h^?1 and 30 mL h^?1 after 1 month of operation, respectively.     

A wavelet approach for the identification of axonal synaptic varicosities from microscope images.

Direct visualization of synapses is a prerequisite to the analysis of the spatial distribution patterns of synaptic systems. Such an analysis is essential to the understanding of synaptic circuitry. In order to facilitate the visualization of individual synapses at the subcellular level from microscope images, we have introduced a wavelet-based approach for the semiautomated recognition of axonal synaptic varicosities. The proposed approach to image analysis employs a family of redundant wavelet representations. They are specifically designed for the recognition of signal peaks, which correspond to the presence of axonal synaptic varicosities. In this paper, the two-dimensional image of an axon together with its synaptic varicosities is first transformed into a one-dimensional (1-D) profile in which the axonal varicosities are represented by peaks in the signal. Next, by decomposing the 1-D profile in the differential wavelet domain, we employ the multi-scale point-wise product to distinguish between peaks and noises. The ability to separate the true signals (due to synaptic varicosities) from noise makes possible a reliable and accurate recognition of axonal synaptic varicosities. The proposed algorithms are also designed with a variable threshold that effectively allows variable sensitivities in varicosity detection. The algorithm has been systematically validated using images containing varicosities (< or =30) that have been consistently identified by seven human observers. The proposed algorithm can give high sensitivity and specificity with appropriate threshold. The results have indicated that the semiautomatic approach is satisfactory for processing a variety of microscopic images of axons under different conditions.     

Microstructure,optical and dielectric properties of cobalt-doped zinc ferrite nanostructures

Journal of Materials Science: Materials in Electronics - In the present work, we have explored the physical properties of ZnFe2?xCoxO4 (0?≤?x?≤?0.06)...     

Mixed type symmetric duality for multiobjective variational problems with cone constraints

In this study, a pair of multiobjective variational mixed symmetric dual programs involving cone constraints is presented and usual duality results are established using the notion of generalized ‐convexity. Self‐duality is discussed under additional condition of skew symmetry, and a time‐independence (static) version of the problems is also incorporated.